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1

Walking Problems  

MedlinePLUS

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

2

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

3

Lévy walks  

E-print Network

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

V. Zaburdaev; S. Denisov; J. Klafter

2015-01-23

4

Walking abnormalities  

MedlinePLUS

... the leg will improve as the leg heals. Physical therapy almost always helps with short-term or long- ... safety reasons, especially on uneven ground. See a physical therapist for exercise therapy and walking retraining. For a scissors gait: People ...

5

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...

6

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.

2012-06-26

7

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

8

JOIN THE WALK! HANDLEMAN WALK FOR AUTISM  

E-print Network

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

Cheng, Mei-Fang

9

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

10

Quantum walks on graphs  

Microsoft Academic Search

We set the ground for a theory of quantum walks on graphs-the generalization of random walks on finite graphs to the quantum world. Such quantum walks do not converge to any stationary distribution, as they are unitary and reversible. However, by suitably relaxing the definition, we can obtain a measure of how fast the quantum walk spreads or how confined

Dorit Aharonov; Andris Ambainis; Julia Kempe; Umesh V. Vazirani

2001-01-01

11

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

12

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

13

Sharif Razzaque Redirected Walking  

E-print Network

ii ABSTRACT Sharif Razzaque Redirected Walking (Under the direction of Frederick P. Brooks Jr Redirected Walking, which by interactively and imperceptibly rotating the virtual scene around her, makes the user turn herself. Under the right conditions, Redirected Walking would cause the user to unknowingly

Whitton, Mary C.

14

Quantum walk computation  

NASA Astrophysics Data System (ADS)

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

Kendon, Viv

2014-12-01

15

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

16

Quantum Walks Norio Konno  

E-print Network

Quantum Walks Norio Konno Yokohama National University Two types of quantum (random) walks, discrete-time (coined) or continuous- time, were introduced as the quantum mechanical extension of the corresponding classical random walks in connection with quantum computing and have been extensively studied over

Schürmann, Michael

17

Walking Wellness. Student Workbook.  

ERIC Educational Resources Information Center

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

Sweetgall, Robert; Neeves, Robert

18

Are random walks random?  

NASA Astrophysics Data System (ADS)

Random walks have been created using the pseudo-random generators in different computer language compilers (BASIC, PASCAL, FORTRAN, C++) using a Pentium processor. All the obtained paths have apparently a random behavior for short walks (?2 14 steps). From long random walks (2 33 steps) different periods have been found, the shortest being 2 18 for PASCAL and the longest 2 31 for FORTRAN and C++, while BASIC had a 2 24 steps period. The BASIC, PASCAL and FORTRAN long walks had even (2 or 4) symmetries. The C++ walk systematically roams away from the origin. Using deviations from the mean-distance rule for random walks, < d2>? N, a more severe criterion is found, e.g. random walks generated by a PASCAL compiler fulfills this criterion to N< 10 000 .

Nogués, J.; Costa-Krämer, J. L.; Rao, K. V.

19

A comparison between human walking and passive dynamic walking  

Microsoft Academic Search

Root mean square error is presented as a quantitative measure for the similarity between human walking and passive dynamic walking. Normalized root mean square error of the hip angle and angular velocity between both walkers in a walking cycle is 6.9% and 12.2% on average, respectively. It shows a strong similarity between human walking and passive dynamic walking. A comparison

Xiuhua Ni; Weishan Chen; Junkao Liu

2009-01-01

20

Loop-weighted Walk  

E-print Network

Loop-weighted walk with parameter $\\lambda\\geq 0$ is a non-Markovian model of random walks that is related to the loop $O(N)$ model of statistical mechanics. A walk receives weight $\\lambda^{k}$ if it contains $k$ loops; whether this is a reward or punishment for containing loops depends on the value of $\\lambda$. A challenging feature of loop-weighted walk is that it is not purely repulsive, meaning the weight of the future of a walk may either increase or decrease if the past is forgotten. Repulsion is typically an essential property for lace expansion arguments. This article circumvents the lack of repulsion and proves, via the lace expansion, that for any $\\lambda\\geq 0$ loop-weighted walk is diffusive in high dimensions.

Tyler Helmuth

2014-10-12

21

The Bug Walk  

NSDL National Science Digital Library

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

Paula Rogers Huff

2005-01-01

22

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

23

Phase resetting of human walking  

E-print Network

This thesis is an investigation of the neural control of unimpaired human walking. Specifically, this work studied the potential for phase resetting of human walking by analyzing results from treadmill walking experiments. ...

Klenk, Daniel E

2011-01-01

24

Walking boot assembly  

NASA Technical Reports Server (NTRS)

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

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

1977-01-01

25

Learning-Walk Continuum  

ERIC Educational Resources Information Center

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

Finch, Peter Dallas

2010-01-01

26

From open quantum walks to unitary quantum walks  

E-print Network

We present an idea to convert to a unitary quantum walk any open quantum walk which is defined on lattices as well as on finite graphs. This approach generalizes to the domain of open quantum walks (or quantum Markov chains) the framework introduced by Szegedy for quantizing Markov chains. For the unitary quantum walks formulated in this article, we define the probability and the mean probability of finding the walk at a node, then derive the asymptotic mean probability.

Chaobin Liu

2015-02-05

27

Quantum walk and potential application  

Microsoft Academic Search

Quantum walk represents a generalised version of the well-known classical random walk. Regardless of their apparent connection, the dynamics of quantum walk is often non-intuitive and far deviate from its classical counterpart. However, despite such potentially superior efficiency in quantum walks, it has yet to be applied to problems of practical importance. In this paper, we will give a brief

J. B. Wang; B. L. Douglas

2010-01-01

28

Walking to health.  

PubMed

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

Morris, J N; Hardman, A E

1997-05-01

29

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

30

What is Gallery Walk?  

NSDL National Science Digital Library

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

31

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.

Dexter Perkins

32

Walking in Traffic  

MedlinePLUS

... Travel & Motor Vehicle Safety En Español Travel & Motor Vehicle Safety Walking in Traffic Protect yourself and your ... traffic. Kids are small, unpredictable, and cannot judge vehicle distances and speeds. When kids get older, teach ...

33

BIOPHYSICS: Myosin Motors Walk the Walk  

NSDL National Science Digital Library

Access to the article is free, however registration and sign-in are required. Myosin molecular motors move along actin filaments to drive, for example, muscle contraction or the intracellular trafficking of vesicles. However, it has not been clear whether myosin V moves along actin filaments in a hand-over-hand or inchworm fashion. In their Perspective, Molloy and Veigel explain new work (Yildiz et al.) that provides evidence in support of the hand-over-hand model for how myosin V walks along actin.

Justin E. Molloy (National Institute for Medical Research; Division of Physical Biochemistry)

2003-06-27

34

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

2013-01-01

35

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

36

Walking with a Slower Friend  

ERIC Educational Resources Information Center

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

Bailey, Herb; Kalman, Dan

2011-01-01

37

Walk Across Texas! Recruitment Brochure  

E-print Network

Walk Across Texas! Recruitment Brochure See next page for ordering instructions #12;How to Order Walk Across Texas! Marketing Materials from the Texas A&M AgriLife Extension Bookstore 1. Go to: http where you can order the Walk Across Texas! brochures, bookmark or mini poster FREE. 4. Then, search

38

Walk Across Texas walkacrosstexas.tamu.edu Walk Across Texas Packet for Schools  

E-print Network

Walk Across Texas walkacrosstexas.tamu.edu Walk Across Texas Packet for Schools Thank you for your interest in Walk Across Texas! Walking is a great way for children to become more physically active. Walk Across Texas is a great way to get children walking. Classes of children may Walk Across Texas

39

Walking Out Graphs  

ERIC Educational Resources Information Center

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…

Shen, Ji

2009-01-01

40

Accelerating Random Walks  

Microsoft Academic Search

In recent years, there has been much research on local search techniques for solving constraint satisfaction problems, including Boolean satisfiability problems. Some of the most successful procedures combine a form of random walk with a greedy bias. These procedures are quite effective in a number of problem domains, for example, constraint-based planning and scheduling, graph coloring, and hard random problem

Wei Wei; Bart Selman

2002-01-01

41

The walking robot project  

NASA Technical Reports Server (NTRS)

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

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

1991-01-01

42

The Strands Walk.  

ERIC Educational Resources Information Center

The Strands Walk is a simple field trip activity designed to acquaint students with an unfamiliar area and with each other. The teacher's role in this activity is to help the students express what they observe, experience, and question. Methods of study and concepts for emphasis are included in this publication. A major portion of the booklet is…

Crider, Tom, Ed.

43

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

44

Random Walk Experiment  

NSDL National Science Digital Library

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

Kyle Siegrist

45

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.

46

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 an…

Schuster, Dwight

2008-01-01

47

Deterministic Walks with Choice  

SciTech Connect

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

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

2014-01-10

48

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 history,…

Salia, Hannah

2010-01-01

49

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

50

The Longest Walk.  

ERIC Educational Resources Information Center

Focusing on the views of Ernie Peters, Phillip Deere, and Larry Leventhal which were considered by the authors as reflective and representative of the Longest Walk participants, this article also presented an "Affirmation of Sovereignty of the Indigenous people of the Western Hemisphere." (RTS)

American Indian Journal, 1978

1978-01-01

51

Unitary equivalence of quantum walks  

NASA Astrophysics Data System (ADS)

A simple coined quantum walk in one dimension can be characterized by a SU (2) operator with three parameters which represents the coin toss. However, different such coin toss operators lead to equivalent dynamics of the quantum walker. In this manuscript we present the unitary equivalence classes of quantum walks and show that all the nonequivalent quantum walks can be distinguished by a single parameter. Moreover, we argue that the electric quantum walks are equivalent to quantum walks with time dependent coin toss operator.

Goyal, Sandeep K.; Konrad, Thomas; Diósi, Lajos

2015-01-01

52

[Walking abnormalities in children].  

PubMed

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

Segawa, Masaya

2010-11-01

53

Relativistic Weierstrass random walks.  

PubMed

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

Saa, Alberto; Venegeroles, Roberto

2010-08-01

54

A Walk Through Newark  

NSDL National Science Digital Library

The famous Walking Tour series on WNET, New York's public television station went to Newark, New Jersey, for the first tour outside of New York. Visitors who missed the show, or prefer a more interactive experience, will definitely enjoy the walking tour via the website. The two hosts of the tour, historian Barry Lewis, and former morning show host David Hartman, give visitors a multimedia tour which starts with a video clip in the "About the Program" link. Visitors will find that the "History of Newark" link is divided into four time periods, including "Colonial Founding", "Industrial Revolution", and "The Riots". The "See the Sites" link offers a more interactive approach for visitors to get to know Newark. There are 360-degree virtual tours of "Penn Station Newark", "Trinity Church" and "Military Park" on the left hand side of the page, and a map with 21 hotspots on it of Newark's "best landmarks and areas".

55

Mussels realize Weierstrassian Lévy walks as composite correlated random walks  

PubMed Central

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

Reynolds, Andy M.

2014-01-01

56

Passive dynamic quadrupedal walking  

Microsoft Academic Search

It has been shown that a suitably designed biped will walk passively, i.e., without actuation or control, down a shallow slope. This paper extends the concept from bipedal to quadrupedal locomotion. A simple rimless-wheel model is analyzed first to provide a few basic insights, followed by a more complex model with freely-swinging legs. The gaits found for the quadruped are

Adam C. Smith; Matthew D. Berkemeier

1997-01-01

57

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.

Samuel E. Zordak

2000-01-01

58

The Oxford Science Walk  

NSDL National Science Digital Library

Maintained by The Museum of the History of Science, the Oxford Virtual Science Walk Web site explores "some of the most important and interesting historic scientific sites in Oxford, from the time of the founding of the University in the 13th century and the work of Friar Bacon to advancements in modern science such as the development of penicillin." Visitors visit thirteen sites and view an illustration of each along with a short but informative description.

Huxley, Sophie.

1969-12-31

59

Bob Miller's Light Walk  

NSDL National Science Digital Library

Artist Bob Miller's "Light Walk" at the Exploratorium is always an eye-opening experience for students and teachers alike. His unique discoveries will change the way you look at light, shadow, and images. The author includes activities such as doing your own lightwalk, building a pinhole viewer, building a pinhole camera, and slide projector activities. The author also provides an additional bibliography that is accompanied by reading materials. External links to related internet resources are also provided.

Miller, Bob

60

Walking Control of Quasi Passive Dynamic Walking Robot \\  

Microsoft Academic Search

Passive-dynamic-walking (PDW) has been noticed in the research of biped walking robots. In this paper, combining our previous control methods, we provide a new control method of quasi-PDW. Quasi-PDW means that a robot usually does PDW without any input torques, and the actuators of the robot are used just only when the walking begins or disturbances come in. The first

Yasuhiro Sugimoto; Koichi Osuka

2004-01-01

61

a walking tour of ALONG THE OLIVE WALK  

E-print Network

a walking tour of Caltech ALONG THE OLIVE WALK #12;2 The California Institute of Technology Medal of Technology. Welcome to Caltech! Caltech offers an unparalleled undergraduate education and research experience through joint programs with City of Hope, Huntington Memorial Hospital, Children

Stoltz, Brian M.

62

A Walk Through Time  

NSDL National Science Digital Library

The Physics Laboratory of the National Institute of Standards and Technology (NIST) provides A Walk Through Time, a site devoted to examining the question of how humans have measured time throughout history. In one example, Egyptians created the first timepiece (shadow clock or sundial) in the approximate year of 1500 BC to measure "hours." Nowadays, the Physics Laboratory develops and operates the "standards of time and frequency and coordinates them with other world standards." Those interested in timekeeping methods and an historical perspective on the evolution of time measurement will find this site fascinating.

63

Derandomization of Euclidean Random Walks  

Microsoft Academic Search

We consider the problem of derandomizing random walks in the Euclidean space Rk. We show that for k = 2, and in some cases in higher dimensions, such walks can be simulated in Logspace using only poly-logarithmically many truly random bits. As a corollary, we show that the Dirichlet Problem can be determinis- tically simulated in space O(log n p

Ilia Binder; Mark Braverman

2007-01-01

64

Slow-walking inflation  

SciTech Connect

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

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

2013-01-01

65

Water-walking devices  

NASA Astrophysics Data System (ADS)

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

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

66

Visual control of walking velocity.  

PubMed

Even if optical correlates of self-motion velocity have already been identified, their contribution to the control of displacement velocity remains to be established. In this study, we used a virtual reality set-up coupled to a treadmill to test the role of both Global Optic Flow Rate (GOFR) and Edge Rate (ER) in the regulation of walking velocity. Participants were required to walk at a constant velocity, corresponding to their preferred walking velocity, while eye height and texture density were manipulated. This manipulation perturbed the natural relationship between the actual walking velocity and its optical specification by GOFR and ER, respectively. Results revealed that both these sources of information are indeed used by participants to control walking speed, as demonstrated by a slowing down of actual walking velocity when the optical specification of velocity by either GOFR or ER gives rise to an overestimation of actual velocity, and vice versa. Gait analyses showed that these walking velocity adjustments result from simultaneous adaptations in both step length and step duration. The role of visual information in the control of self-motion velocity is discussed in relation with other factors. PMID:21345354

François, Matthieu; Morice, Antoine H P; Bootsma, Reinoud J; Montagne, Gilles

2011-06-01

67

Low impedance walking robots.  

PubMed

For both historical and technological reasons, most robots, including those meant to mimic animals or operate in natural environments,3 use actuators and control systems that have high (stiff) mechanical impedance. By contrast, most animals exhibit low (soft) impedance. While a robot's stiff joints may be programmed to closely imitate the recorded motion of an animal's soft joints, any unexpected position disturbances will generate reactive forces and torques much higher for the robot than for the animal. The dual of this is also true: while an animal will react to a force disturbance by significantly yielding position, a typical robot will greatly resist.These differences cause three deleterious effects for high impedance robots. First, the higher forces may cause damage to the robot or to its environment (which is particularly important if that environment includes people). Second, the robot must acquire very precise information about its position relative to the environment so as to minimize its velocity upon impact. Third, many of the self-stabilizing effects of natural dynamics are "shorted out"4 by the robot's high impedance, so that stabilization requires more effort from the control system.Over the past 5 yr, our laboratory has designed a series of walking robots based on "Series-Elastic Actuators" and "Virtual Model Control." Using these two techniques, we have been able to build low-impedance walking robots that are both safe and robust, that operate blindly without any model of upcoming terrain, and that add minimal control effort in parallel to their self-stabilizing passive dynamics. We have discovered that it is possible to achieve surprisingly effective ambulation from rather simple mechanisms and control systems. After describing the historical and technological motivations for our approach, this paper gives an overview of our methods and shows some of the results we have obtained. PMID:21708707

Pratt, Gill Andrews

2002-02-01

68

Passive dynamic walking with elastic energy  

Microsoft Academic Search

This paper presents passive dynamic walking with elastic energy. We propose a new type of passive dynamic walking robot. by adding elastic materials such as spring or rubber between a supporting leg and a swing leg of the robot By utilizing restoring force of spring or rubber, we can make the passive dynamic walking robot easily walk since the crotch

Masahiro Mizuno; Hiroshi Ohtake; Kazuo Tanaka; Hua O. Wang

2008-01-01

69

Fault-Tolerant Quantum Walks  

E-print Network

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

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

2014-08-06

70

The effect of walking speed and avatars on Redirected Walking Master Thesis  

E-print Network

The effect of walking speed and avatars on Redirected Walking Master Thesis Fakultät Informatik Abstract 5 1 Introduction 6 1.1 Related Work 8 1.1.1 The invention of Redirected Walking 9 1.1.2 Further advancements in Redirected Walking 9 1.1.3 Dynamic controller for Redirected Walking 10 1.1.4 Using distracters

71

Quantum Snake Walk on Graphs  

E-print Network

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

Ansis Rosmanis

2010-08-18

72

Walking Robot Locomotion System Conception  

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

73

Quantum walks on embedded hypercubes  

NASA Astrophysics Data System (ADS)

It has been proved by Kempe that discrete quantum walks on the hypercube (HC) hit exponentially faster than the classical analog. The same was also observed numerically by Krovi and Brun for a slightly different property, namely, the expected hitting time. Yet, to what extent this striking result survives in more general graphs is to date an open question. Here, we tackle this question by studying the expected hitting time for quantum walks on HCs that are embedded into larger symmetric structures. By performing numerical simulations of the discrete quantum walk and deriving a general expression for the classical hitting time, we observe an exponentially increasing gap between the expected classical and quantum hitting times, not only for walks on the bare HC, but also for a large family of embedded HCs. This suggests that the quantum speedup is stable with respect to such embeddings.

Makmal, Adi; Zhu, Manran; Manzano, Daniel; Tiersch, Markus; Briegel, Hans J.

2014-08-01

74

Quantum snake walk on graphs  

SciTech Connect

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

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

2011-02-15

75

Gallery Walk Questions on Rivers  

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 rivers. The questions are organized according to the cognitive level ...

76

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 ...

77

Gallery Walk Questions about Glaciers  

NSDL National Science Digital Library

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

78

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 ...

79

Gallery Walk Questions about 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 climate. The questions are organized according to the cognitive level ...

80

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 student

Ji Shen

2009-12-01

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

Walking behavior in technicolored GUTs  

NASA Astrophysics Data System (ADS)

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

Doff, A.

2009-03-01

83

Science Sampler: The Element Walk  

NSDL National Science Digital Library

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

Dennis Smithenry

2010-10-01

84

Branching Random Walk with Catalysts  

Microsoft Academic Search

Shnerb et al. (2000), (2001) studied the following system of interacting particles on Zd: There are two kinds of particles, called A-particles and B-particles. The A-particles perform continuous time simple random walks, independently of each other. The jumprate of each A-particle is DA. The B-particles perform continuous time simple random walks with jumprate DB, but in addition they die at

Harry Kesten; Vladas Sidoravicius

85

Quantum Walk with Jumps  

E-print Network

We analyze a special class of 1-D quantum walks (QWs) realized using optical multi-ports. We assume non-perfect multi-ports showing errors in the connectivity, i.e. with a small probability the multi- ports can connect not to their nearest neighbor but to another multi-port at a fixed distance - we call this a jump. We study two cases of QW with jumps where multiple displacements can emerge at one timestep. The first case assumes time-correlated jumps (static disorder). In the second case, we choose the positions of jumps randomly in time (dynamic disorder). The probability distributions of position of the QW walker in both instances differ significantly: dynamic disorder leads to a Gaussian-like distribution, while for static disorder we find two distinct behaviors depending on the parity of jump size. In the case of even-sized jumps, the distribution exhibits a three-peak profile around the position of the initial excitation, whereas the probability distribution in the odd case follows a Laplace-like discrete distribution modulated by additional (exponential) peaks for long times. Finally, our numerical results indicate that by an appropriate mapping an universal functional behavior of the variance of the long-time probability distribution can be revealed with respect to the scaled average of jump size.

H. Lavi?ka; V. Poto?ek; T. Kiss; E. Lutz; I. Jex

2011-06-20

86

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

PubMed Central

Background Walk Score® and Transit Score® are open-source measures of the neighborhood built environment to support walking (“walkability”) and access to transportation. Purpose To investigate associations of Street Smart Walk Score and Transit Score with self-reported transport and leisure walking using data from a large multi-city and diverse population-based sample of adults. Methods Data from a sample of 4552 residents of Baltimore MD; Chicago IL; Forsyth County NC; Los Angeles CA; New York NY; and St. Paul MN from the Multi-Ethnic Study of Atherosclerosis (2010–2012) were linked to Walk Score and Transit Score (collected in 2012). Logistic and linear regression models estimated ORs of not walking and mean differences in minutes walked, respectively, associated with continuous and categoric Walk Score and Transit Score. All analyses were conducted in 2012. Results After adjustment for site, key sociodemographic, and health variables, a higher Walk Score was associated with lower odds of not walking for transport and more minutes/week of transport walking. Compared to those in a “walker’s paradise,” lower categories of Walk Score were associated with a linear increase in odds of not transport walking and a decline in minutes of leisure walking. An increase in Transit Score was associated with lower odds of not transport walking or leisure walking, and additional minutes/week of leisure walking. Conclusions Walk Score and Transit Score appear to be useful as measures of walkability in analyses of neighborhood effects. PMID:23867022

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

2013-01-01

87

Walking in (affective) circles: can short walks enhance affect?  

PubMed

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 known about the affective outcomes of short bouts of walking and extant findings are equivocal. Four experimental studies examined the affective responses associated with short (10- to 15-min) bouts of walking using a dimensional conceptual model of affect, namely, the circumplex. Results consistently showed that walking was associated with shifts toward increased activation and more positive affective valence. Recovery from walking for 10-15 min was associated with a return toward calmness and relaxation. This pattern, was robust across different self-report measures of the circumplex affective dimensions, across ecological settings (field and laboratory), across time, and across samples. PMID:10863677

Ekkekakis, P; Hall, E E; VanLanduyt, L M; Petruzzello, S J

2000-06-01

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 on ballast impacts balance.  

PubMed

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

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

2014-01-01

90

Quantum walks and reversible cellular automata  

NASA Astrophysics Data System (ADS)

We obtain a conserved quantity for a reversible cellular automaton derived from a discrete-time quantum walk in one dimension. As a corollary, we give detailed information regarding the evolution of the quantum walk.

Konno, N.; Mistuda, K.; Soshi, T.; Yoo, H. J.

2004-10-01

91

Efficient Walking Control of Robot with Torso Based on Passive Dynamic Walking  

Microsoft Academic Search

This paper studies a biped walking robot with torso based on virtual passive dynamic walking. First we realize a walking motion on a slope using input to the torso where the desired angle to the torso is synchronized to the angle between foots. Secondly we introduce criterion functions for the motion and make the walking motion more efficient by adjusting

H. Sasaki; M. Yamakita

2007-01-01

92

Level-Ground Walk Based on Passive Dynamic Walking for a Biped Robot with Torso  

Microsoft Academic Search

This study presents a design technique of an efficient biped walking robot on level ground with a simple mechanism based on passive-dynamic walking. A torso is used to generate active power replacing gravity used in passive walk. Swing-leg control is introduced to create a steady gait. Numerical simulations show that a biped robot with knees and a torso can walk

Terumasa Narukawa; Masaki Takahashi; Kazuo Yoshida

2007-01-01

93

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

E-print Network

to achieve reliable long distance walking by using passive dynamic principles. In spring 2005, the Fe teamTESTING OF THE FE WALKING ROBOT MAY 2006 1 Testing of the FE Walking Robot Elianna R Weyer, May and result of testing the FE walking robot during spring 2006. Improve- ments in code and launch technique

Ruina, Andy L.

94

Foot placement in a body reference frame during walking and its relationship to hemiparetic walking performance  

E-print Network

Foot placement in a body reference frame during walking and its relationship to hemiparetic walking Keywords: Walking Biomechanics Foot placement Stroke Spatiotemporal parameters a b s t r a c t Background: Foot placement during walking is closely linked to the body position, yet it is typically quantified

95

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

96

Energy Gallery Walk  

NSDL National Science Digital Library

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

Katharine Ellis

97

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 a…

Vukovic, Paul

2011-01-01

98

REAL-WALKING MODELS IMPROVE WALKING-IN-PLACE SYSTEMS  

E-print Network

to the faculty of the University of North Carolina at Chapel Hill in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Computer Science. Chapel Hill 2010 Approved by oral exams. · Rich Holloway ­ friend and boss ­ helped me see the big picture during our many walks

North Carolina at Chapel Hill, University of

99

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

100

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

101

RANDOM WALK IN DETERMINISTICALLY CHANGING ENVIRONMENT  

E-print Network

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

Liverani, Carlangelo

102

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

103

Quantum random walks: an introductory overview  

Microsoft Academic Search

This article aims to provide an introductory survey on quantum random walks. Starting from a physical effect to illustrate the main ideas we will introduce quantum random walks, review some of their properties and outline their striking differences to classical walks. We will touch upon both physical effects and computer science applications, introducing some of the main concepts and language

J. KEMPE

2003-01-01

104

Online Trajectory Generation for Omnidirectional Biped Walking  

Microsoft Academic Search

This paper describes the online generation of tra- jectories for omnidirectional walking on two legs. The gait can be parameterized using walking direction, walking speed, and rotational speed. Our approach has a low computational complexity and can be implemented on small onboard computers. We tested the proposed approach using our humanoid robot Jupp. The competitions in the RoboCup soccer domain

Sven Behnke

2006-01-01

105

Reinforced walks in two and three dimensions  

Microsoft Academic Search

In probability theory, reinforced walks are random walks on a lattice (or more generally a graph) that preferentially revisit neighboring 'locations' (sites or bonds) that have been visited before. In this paper, we consider walks with one-step reinforcement, where one preferentially revisits locations irrespective of the number of visits. Previous numerical simulations (A Ordemann et al 2001 Phys. Rev. E

Jacob G. Foster; Peter Grassberger; Maya Paczuski

2009-01-01

106

Stereo matching using random walks  

Microsoft Academic Search

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

Rui Shen; Irene Cheng; Xiaobo Li; Anup Basu

2008-01-01

107

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

108

A Random Walk to Capacitance  

E-print Network

and for a pair of parallel plates. The cube, though, is a shape for which no formula is known. In this case study a random walk on the surface of an object, we will need to generate points that are uniformly distributed for generating points that are uniformly distributed on the surface of a sphere: · One method can be found

O'Leary, Dianne P.

109

Closed walks for community detection  

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

110

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 composition…

Cardany, Audrey Berger

2011-01-01

111

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

112

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.

113

Walk Through a Hydroelectric Project  

NSDL National Science Digital Library

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

114

AQUA: An underwater walking robot  

Microsoft Academic Search

Based on the RHHex hexapod robot, the AQUA robot is an aquatic robot that swims via the motion of its legs, rather than using thrusters and control surfaces for propulsion. Through an appropriate set of gaits, the AQUA vehicle is capable of five-degree-of-freedom motion in the open water, it can swim along the surface and it can walk along the

Christina Georgiades; Andrew German; Andrew Hogue; Hui Liu; Chris Prahacs; Arlene Ripsman; Robert Sim; Pifu Zhang; Martin Buehler; Gregory Dudek; Michael Jenkin; Evangelos Milios

115

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

116

Water-Walking Submitted by  

E-print Network

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

Bush, John W.M.

117

Statistics of Anisotropic Random Walks.  

NASA Astrophysics Data System (ADS)

We discuss the three different types of anisotropic random walks based on Monte Carlo simulations and real space renormalization group transformations. Our work for biased self-avoiding walks using Monte Carlo simulation coupled with scaling analyses suggests qualitative differences in the effect of excluded volume on the chain conformation in the stiff limit between two and three dimensions in a manner similar to a suggestion made by Petschek. In the limit of gauche weight p to 0 and contour length N to infty, we find scaling for the mean square end-to-end distance < R^2>> with the crossover exponent one as before; however, the scaling function in three dimensions closely matches the random stiff chain results with no excluded volume while that in two dimensions exhibits marked deviations. Our cell renormalization approach also confirms the crossover exponent to be exactly one in any dimensions and for all cell sizes. Our work also shows, by use of renormalization flows, a substantial difference in the crossover between two and three dimensions in the limit of N toinfty for fixed p. In three dimensions a crossover seems to occur first to random walk limit and then to self-avoiding walk limit, while in two dimensions, it seems to occur directly to self-avoiding walk limit in agreement with our observations based on Monte Carlo simulation. We also study self-avoiding Levy flights in one dimension by Monte Carlo simulation. We find very large corrections to scaling in the node-avoiding Levy flights for a wide range of mu and also, surprisingly, that the moments of the end-to-end distance of the node-avoiding Levy flights are greater than those of path-avoiding Levy flight when they both exist and are finite. Based on these observations we conclude that the morphology of the node-avoiding Levy flights is far more complex than that of the path-avoiding Levy flights or the random Levy flights, and that the node-avoiding and path-avoiding Levy flights are certainly in different universality classes in one dimension. We also present new results of Monte Carlo simulation for self-avoiding walks on randomly diluted square and simple cubic lattices performed for p very close to the percolation thresholds. The asymptotic behavior obtained is very different from the only previous work of this kind by Kremer for the diamond lattice. While the previous work reported a large increase of Flory exponent compared to the undiluted lattice, our results indicate a behavior rather similar to the ordinary self-avoiding walks.

Lee, Sang Bub

118

Walking and Running of a Quadruped Robot on Irregular Terrain  

E-print Network

bound of the cyclic period of walking TomCat [Jul. 2003] #12;11 Passive Dynamic Walking A walking CPG? ·passive dynamic walk ·spring-damper neural system model (CPG + reflexes) passive dynamics is encoded into parameters of the neural systemargument (BC:2002) essential for dynamic walking by Kimura

Kimura, Hiroshi

119

Braiding Interactions in Anyonic Quantum Walks  

E-print Network

The anyonic quantum walk is a dynamical model describing a single anyon propagating along a chain of stationary anyons and interacting via mutual braiding statistics. We review the recent results on the effects of braiding statistics in anyonic quantum walks in quasi-one dimensional ladder geometries. For anyons which correspond to spin-1/2 irreps of the quantum groups $SU(2)_k$, the non-Abelian species $(1walk. The decoherence is strong enough to reduce the walk on the infinite ladder to classical like behaviour. We also present numerical results on mixing times of $SU(2)_2$ or Ising model anyon walks on cyclic graphs. Finally, the possible experimental simulation of the anyonic quantum walk in Fractional Quantum Hall systems is discussed.

Lauri J. Lehman; Vaclav Zatloukal; Jiannis K. Pachos; Gavin K. Brennen

2012-10-12

120

An experimental study of passive dynamic walking  

Microsoft Academic Search

SUMMARY A two-straight-legged walking mechanism with flat feet is designed and built to study the passive dynamic gait. It is shown that the mechanism having flat feet can exhibit passive dynamic walking as those with curved feet, but the walking efficiency is significantly lower. It is also shown that the balancing mass and its orientation are etfective for controlling side-to-side

Q. Wu; N. Sabet

2004-01-01

121

How Well Do Random Walks Parallelize?  

Microsoft Academic Search

A random walk on a graph is a process that explores the graph in a random way: at each step the walk is at a vertex of the\\u000a graph, and at each step it moves to a uniformly selected neighbor of this vertex. Random walks are extremely useful in computer\\u000a science and in other fields. A very natural problem that

Klim Efremenko; Omer Reingold

2009-01-01

122

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

123

Biomechanics and muscle coordination of human walking  

Microsoft Academic Search

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

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

2002-01-01

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

2012-04-01

125

Efficient quantum circuit implementation of quantum walks  

SciTech Connect

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

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

2009-05-15

126

The Self-Avoiding Random Walk  

NSDL National Science Digital Library

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

Buldyrev, Sergey

127

Walking-age analyzer for healthcare applications.  

PubMed

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

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

2014-05-01

128

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

Microsoft Academic Search

A growing body of health and policy research suggests residential neighborhood density and street connectivity affect walking and total physical activity, both of which are important risk factors for obesity and related chronic diseases. The authors report results from their methodologically novel Twin Cities Walking Study; a multilevel study which examined the relationship between built environments, walking behavior and total

J Michael Oakes; Ann Forsyth; Kathryn H Schmitz

2007-01-01

129

Control of Bipedal Walking Exploiting Postural Reflexes and Passive Dynamics  

E-print Network

Control of Bipedal Walking Exploiting Postural Reflexes and Passive Dynamics Tobias Luksch biology to walking machines. Examples include the exploitation of passive dynamics and elasticities [6 lacking in efficiency, velocity, and robustness. Thus, a control concept for dynamic walking based

Berns, Karsten

130

Topology of Minimal Walking Technicolor  

E-print Network

We perform a lattice study of the topological susceptibility and instanton size distribution of the $\\su{2}$ gauge theory with two adjoint Dirac fermions (also known as Minimal Walking Technicolor), which is known to be in the conformal window. In the theory deformed with a small mass term, by drawing a comparison with the pure gauge theory, we find that topological observables are decoupled from the fermion dynamics. This provides further evidence for the infrared conformality of the theory. A study of the instanton size distribution shows that this quantity can be used to detect the onset of finite size effects.

Ed Bennett; Biagio Lucini

2013-04-25

131

Passive dynamic walking model with upper body  

Microsoft Academic Search

SUMMARY This paper presents the simplest walking model with an upper body. The model is a passive dynamic walker, i.e. it walks down a slope without motor input or control. The upper body is confined to the midway angle of the two legs. With this kinematic constraint, the model has only two degrees of freedom. The model achieves surprisingly successful

Martijn Wisse; Arend L. Schwab; Frans C. T. Van Der Helm

2004-01-01

132

Open Quantum Walks: a short introduction  

NASA Astrophysics Data System (ADS)

The concept of open quantum walks (OQW), quantum walks exclusively driven by the interaction with the external environment, is reviewed. OQWs are formulated as discrete completely positive maps on graphs. The basic properties of OQWs are summarised and new examples of OQWs on Bbb Z and their simulation by means of quantum trajectories are presented.

Sinayskiy, Ilya; Petruccione, Francesco

2013-06-01

133

Many random walks are faster than one  

Microsoft Academic Search

We pose a new and intriguing question motivated by dis- tributed computing regarding random walks on graphs: How long does it take for several independent random walks, starting from the same vertex, to cover an entire graph? We study the cover time-the expected time required to visit every node in a graph at least once-and we show that for a

Noga Alon; Chen Avin; Michal Koucký; Gady Kozma; Zvi Lotker; Mark R. Tuttle

2008-01-01

134

A random walk approach to quantum algorithms  

Microsoft Academic Search

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

Vivien M. Kendon

2006-01-01

135

NORTH AND SOUTH JERSEY PASTURE WALKS  

E-print Network

proper pasture management while walking through two equine farms in New Jersey. You couldn't ask by Rutgers University Equine Science Center and sponsored by Natural Resources Conservation ServiceNORTH AND SOUTH JERSEY PASTURE WALKS Join Rutgers University pasture specialists as they discuss

Chen, Kuang-Yu

136

Walking on Water: Biolocomotion at the Interface  

E-print Network

tension, insects, spiders, lizards Abstract We consider the hydrodynamics of creatures capable; for other creatures, walking on water is a skill employed sparingly, often to avoid predators. Although various motives for walking on water are mentioned, we focus here on how rather than why creatures do so

Bush, John W.M.

137

Welly-Walks for Science Learning  

ERIC Educational Resources Information Center

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

Fradley, Carol

2006-01-01

138

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

139

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

140

Walking in circles: a modelling approach.  

PubMed

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

Maus, Horst-Moritz; Seyfarth, Andre

2014-10-01

141

Indirect Force Measurement for Hydraulic Walking Robot  

Microsoft Academic Search

Force sensing is an important issue for the control of legged robots. In this paper an indirect force measurement for hydraulic walking robots is presented. The test case is ROBOCLIMBER, a bulky, quadruped climbing and walking machine whose weighty legs enable it to carry out heavy-duty drilling operations. The paper shows how the placement of pressure transducers at both ends

S. Nabulsi; J. F. Sarria; M. A. Armada

2007-01-01

142

Strongly trapped two-dimensional quantum walks  

NASA Astrophysics Data System (ADS)

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

Kollár, B.; Kiss, T.; Jex, I.

2015-02-01

143

Toe walking in autism: further observations.  

PubMed

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

Accardo, Pasquale J; Barrow, William

2015-04-01

144

Exploring topological phases with quantum walks  

NASA Astrophysics Data System (ADS)

The quantum walk was originally proposed as a quantum mechanical analogue of the classical random walk, and has since become a powerful tool in quantum information science. In this talk, we show that the dynamical protocols called discrete time quantum walks provide a versatile platform for studying topological phases, which are currently the subject of intense theoretical and experimental investigation. In particular, we demonstrate that recent experimental realizations of quantum walks simulate a non-trivial one dimensional topological phase. With simple modifications, the quantum walk can be engineered to realize all of the topological phases which have been classified in one and two dimensions. We further discuss the existence of robust edge modes at phase boundaries, which provide experimental signatures for the non-trivial topological character of the system. Reference: T.Kitagawa, M.Ruder, E.Berg, and E. Demler, Phys. Rev. A 82, 033429 (2010)

Kitagawa, Takuya; Rudner, Mark; Berg, Erez; Demler, Eugene

2011-03-01

145

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. PMID:21937285

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

2011-01-01

146

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. PMID:19890163

Rabkin, Janice; Sharify, Denise; Song, Lin

2009-01-01

147

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

2011-12-01

148

Built Environment Correlates of Walking: A Review  

PubMed Central

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

Saelens, Brian E.; Handy, Susan L.

2010-01-01

149

Factors Influencing Whether Children Walk to School  

PubMed Central

Few studies have evaluated multiple levels of influence simultaneously on whether children walk to school. A large cohort of 4,338 subjects from ten 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

2015-01-01

150

Stably Extending Two-Dimensional Bipedal Walking to Three Dimensions  

E-print Network

dynamically sta- ble bipedal walking were concerned with passive two- dimensional (2D) bipeds walking down the use of hybrid zero dynamics. I. INTRODUCTION The central goal of research in bipedal robotic walking been shown that for certain shallow slopes, these passive bipeds have stable walking gaits

Ames, Aaron

151

Reinforcement Learning Control for Biped Robot Walking on Uneven Surfaces  

E-print Network

of (passive) dynamic walking are far simpler than the traditional fully- controlled walking robots, while. INTRODUCTION Since McGeer introduced the concept of passive dynamic walking [1], a number of energy achieving a more natural gait and consuming less energy. However, lightly actuated dynamic walking robots

152

Correct Software Synthesis for Stable Speed-Controlled Robotic Walking  

E-print Network

control [23], passive walking [7], and hybrid zero dynamics [24], to name only a few. In this paper, we parameters for fixed speed walking and for transitions between fixed speeds, guaranteeing dynamic stability on the Aldebaran NAO, showing stable walking transitions with dynamically selected speeds. I. INTRODUCTION Walking

Ames, Aaron

153

Demonstration and Analysis of Quadrupedal Passive Dynamic Walking  

Microsoft Academic Search

Animals, including human beings, can travel in a variety of environments adaptively. Legged locomotion makes this possible. However, legged locomotion is temporarily unstable and finding out the principle of walking is an important matter for optimum locomotion strategy or engineering applications. As one of the challenges, passive dynamic walking has been studied on this. Passive dynamic walking is a walking

Kazuhiro Nakatani; Yasuhiro Sugimoto; Koichi Osuka

2009-01-01

154

Biped Walking Pattern Generator allowing Auxiliary ZMP Control  

E-print Network

that ZMP based walking controls lack the adaptivity which is observed in the passive dynamic walk [3], [4], the compliance based walking control [5], the central pattern generator (CPG) [6] or the hybrid zero dynamics [7 parameters like walking cycle or step width are modified to hold consistency of the system dynamics. By using

Treuille, Adrien

155

Virtual passive dynamic walking and energy-based control laws  

Microsoft Academic Search

It has been shown that a simplest walker with suitable parameter choice can walk down a gentle slope without any control forces and generate its steady walking pattern utilizing gravity effect automatically. On the floor, however, the robot cannot exhibit passive walk, so any application methods of passive walk to active walker on the horizontal floor has not been studied

Fumihiko Asano; Masaki Yamakita; Katsuhisa Furuta

2000-01-01

156

Online Appendix to: CyberWalk: Enabling Unconstrained Omnidirectional  

E-print Network

[Meilinger et al. 2007; Campos et al. 2007]. Larger VEs can be accommo- dated by using redirected walkingOnline Appendix to: CyberWalk: Enabling Unconstrained Omnidirectional Walking through Virtual The requirements for enabling real walking through a virtual environment (VE) depend on its size. For small VEs

De Luca, Alessandro

157

Walking and Eating Behavior of Toddlers at 12 Months Old  

ERIC Educational Resources Information Center

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

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

2004-01-01

158

An orbit based control for biomimetic biped walking  

Microsoft Academic Search

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

Xiang Luo; Rui Guo; Chi Zhu

2009-01-01

159

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

160

[Walking assist robot and its clinical application].  

PubMed

The walking assist robot was developed to improve gait disturbance in patients with severe disabilities. The robot had a trunk supporter, power generator and operating arms which held patient's lower extremities and simulated walking, a control unit, biofeedback system, and a treadmill. We applied the robot-aided gait training to three patients with severe gait disturbance induced by stroke, axonal Guillan-Barré syndrome or spinal cord injury, and the walking assist robot turned out to be effective in improving the gait disturbance. PMID:19530565

Kakou, Hiroaki; Shitama, Hideo; Kimura, Yoshiko; Nakamoto, Yoko; Furuta, Nami; Honda, Kanae; Wada, Futoshi; Hachisuka, Kenji

2009-06-01

161

Does getting a dog increase recreational walking?  

PubMed Central

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

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

2008-01-01

162

Introduction Random Walks Random Walks with Tabu Lists In Messages In Nodes Experimental Results Conclusion Routing Algorithms using Random Walks  

E-print Network

Wireless Sensor Network (WSN) a b a b c d e f PP A node has : low memory, low computation power finite Experimental Results Conclusion Routing a b c d e f P a #12;Introduction Random Walks Random Walks with Tabu Lists In Messages In Nodes Experimental Results Conclusion Routing a b c d e f P a d f e P 3 / 34 #12

Devismes, Stéphane

163

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

164

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

2012-07-01

165

William J. Glackens: "The Cedar Walk."  

ERIC Educational Resources Information Center

Provides a lesson plan for primary grade-level students based on William J. Glackens' oil painting, "The Cedar Walk." The goal of the lesson is to introduce students to landscape/seascape painting. (JDH)

Davidson, Marilyn

1986-01-01

166

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 ...

167

Strongly correlated quantum walks in optical lattices.  

PubMed

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

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

2015-03-13

168

Simple expressions for the long walk distance  

E-print Network

The walk distances in graphs are defined as the result of appropriate transformations of the $\\sum_{k=0}^\\infty(tA)^k$ proximity measures, where $A$ is the weighted adjacency matrix of a connected weighted graph and $t$ is a sufficiently small positive parameter. The walk distances are graph-geodetic, moreover, they converge to the shortest path distance and to the so-called long walk distance as the parameter $t$ approaches its limiting values. In this paper, simple expressions for the long walk distance are obtained. They involve the generalized inverse, minors, and inverses of submatrices of the symmetric irreducible singular M-matrix ${\\cal L}=\\rho I-A,$ where $\\rho$ is the Perron root of $A.$

Chebotarev, Pavel; Balaji, R

2011-01-01

169

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

170

Measuring Oscillating Walking Paths with a LIDAR  

PubMed Central

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

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

2011-01-01

171

Strongly correlated quantum walks in optical lattices  

NASA Astrophysics Data System (ADS)

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

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

2015-03-01

172

Real time visualization of quantum walk  

SciTech Connect

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

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

2014-02-20

173

Walking for health in adolescent girls   

E-print Network

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

MacDonald, Mhairi Jane

2014-07-04

174

Asymptotic densities of ballistic Lévy walks  

NASA Astrophysics Data System (ADS)

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

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

2015-02-01

175

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 ...

176

Gallery Walk Questions about the Biosphere  

NSDL National Science Digital Library

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

177

Gallery Walk Questions on Map Reading  

NSDL National Science Digital Library

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

178

Gallery Walk Questions on Atmosphere Composition  

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 atmosphere composition, greenhouse gases, ozone. The questions are ...

179

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 ...

180

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 ...

181

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 ...

182

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 ...

183

Stable dynamic walking over uneven terrain  

E-print Network

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

Manchester, Ian R.

184

Using perceptual illusions for redirected walking.  

PubMed

Redirected walking (RDW) gives users the ability to explore a virtual world by walking in a confined physical space. It inconspicuously guides them on a physical path that might differ from the path they perceive in the virtual world. Exploiting three motion illusions-the change-blindness illusion, the four-stroke motion illusion, and the motion-without-movement illusion-can increase RDW's effectiveness. PMID:24807877

Steinicke, Frank; Bruder, Gerd

2013-01-01

185

Evaluating Walking in Patients with Multiple Sclerosis  

PubMed Central

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

Bennett, Susan

2011-01-01

186

Standardized Questionnaires of Walking & Bicycling Database  

Cancer.gov

This database contains questionnaire items and a list of validation studies for standardized items concerning walking and biking from multiple national and international physical activity questionnaires (PAQs). The purpose of this database is to provide easy access to a large number of items assessing duration and frequency of walking and bicycling in the non-disabled adult population. We also briefly review the results of validation studies identified for some of the PAQs.

187

Random-walk approximation to vacuum cocycles  

Microsoft Academic Search

Quantum random walks are constructed on operator spaces with the aid of\\u000amatrix-space lifting, a type of ampliation intermediate between those provided\\u000aby spatial and ultraweak tensor products. Using a form of Wiener-Ito\\u000adecomposition, a Donsker-type theorem is proved, showing that these walks,\\u000aafter suitable scaling, converge in a strong sense to vacuum cocycles: these\\u000aare vacuum-adapted processes which are

Alexander C. R. Belton

2010-01-01

188

Some Results In Passive-Dynamic Walking  

Microsoft Academic Search

Human walking can be approximated as a mechanical process governed by Newton's laws of motion, and not controlled. Tad McGeer flrst demonstrated, and we have conflrmed, that a two-dimensional legged mechanism with four moving parts can exhibit stable, human-like walking on a range of shallow slopes with no actuation and no control (energy lost in friction and collisions is recovered

Mariano Garcia; Andy Ruina; Michael Coleman; Anindya Chatterjee

1998-01-01

189

Quantum walks with tuneable self-avoidance in one dimension  

PubMed Central

Quantum walks exhibit many unique characteristics compared to classical random walks. In the classical setting, self-avoiding random walks have been studied as a variation on the usual classical random walk. Here the walker has memory of its previous locations and preferentially avoids stepping back to locations where it has previously resided. Classical self-avoiding random walks have found numerous algorithmic applications, most notably in the modelling of protein folding. We consider the analogous problem in the quantum setting – a quantum walk in one dimension with tunable levels of self-avoidance. We complement a quantum walk with a memory register that records where the walker has previously resided. The walker is then able to avoid returning back to previously visited sites or apply more general memory conditioned operations to control the walk. We characterise this walk by examining the variance of the walker's distribution against time, the standard metric for quantifying how quantum or classical a walk is. We parameterise the strength of the memory recording and the strength of the memory back-action on the walker, and investigate their effect on the dynamics of the walk. We find that by manipulating these parameters, which dictate the degree of self-avoidance, the walk can be made to reproduce ideal quantum or classical random walk statistics, or a plethora of more elaborate diffusive phenomena. In some parameter regimes we observe a close correspondence between classical self-avoiding random walks and the quantum self-avoiding walk. PMID:24762398

Camilleri, Elizabeth; Rohde, Peter P.; Twamley, Jason

2014-01-01

190

Quantum walks with tuneable self-avoidance in one dimension  

NASA Astrophysics Data System (ADS)

Quantum walks exhibit many unique characteristics compared to classical random walks. In the classical setting, self-avoiding random walks have been studied as a variation on the usual classical random walk. Here the walker has memory of its previous locations and preferentially avoids stepping back to locations where it has previously resided. Classical self-avoiding random walks have found numerous algorithmic applications, most notably in the modelling of protein folding. We consider the analogous problem in the quantum setting - a quantum walk in one dimension with tunable levels of self-avoidance. We complement a quantum walk with a memory register that records where the walker has previously resided. The walker is then able to avoid returning back to previously visited sites or apply more general memory conditioned operations to control the walk. We characterise this walk by examining the variance of the walker's distribution against time, the standard metric for quantifying how quantum or classical a walk is. We parameterise the strength of the memory recording and the strength of the memory back-action on the walker, and investigate their effect on the dynamics of the walk. We find that by manipulating these parameters, which dictate the degree of self-avoidance, the walk can be made to reproduce ideal quantum or classical random walk statistics, or a plethora of more elaborate diffusive phenomena. In some parameter regimes we observe a close correspondence between classical self-avoiding random walks and the quantum self-avoiding walk.

Camilleri, Elizabeth; Rohde, Peter P.; Twamley, Jason

2014-04-01

191

Grover Search with Lackadaisical Quantum Walks  

E-print Network

Grover's algorithm can be formulated as a quantum particle randomly walking on the complete graph of $N$ vertices, searching for a marked vertex in $\\Theta(\\sqrt{N})$ time. If the walk is lackadaisical, however, then it prefers to stay put, perhaps due to an imperfect implementation of the walk. We model this by giving each vertex $l$ self-loops. For the discrete-time quantum walk using the Ambainis, Kempe, and Rivosh (2005) coin, we get exactly the expected behavior, that the search takes more time to reach a high success probability. Using the phase flip coin, however, for which $l=1$ corresponds exactly to Grover's iterate, yields a completely different behavior---the buildup of success probability is hampered no matter how much time we walk. Furthermore, the first coin is more robust since a speedup over classical search persists when $l$ scales less than $N^2$, whereas the second coin requires that $l$ scale less than $N$. Finally, continuous-time quantum walks differ from both of these discrete-time examples---the self-loops make no difference at all. These behaviors generalize to multiple marked vertices.

Thomas G. Wong

2015-02-16

192

Calcaneal loading during walking and running  

NASA Technical Reports Server (NTRS)

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

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

2000-01-01

193

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. PMID:21399716

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

2010-01-01

194

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

PubMed Central

Background Numerous recommendations have been made for treating idiopathic toe-walking (ITW), but the treatment results have been questioned. The purpose of this study was to investigate whether botulinum toxin A (BTX) improves the walking pattern in ITW as examined with 3-D gait analysis. Participants and methods A consecutive series of 15 children (aged 5–13 years) were enrolled in the study. The children underwent a 3-D gait analysis prior to treatment with a total of 6 units/kg bodyweight Botox® in the calf muscles and an exercise program. The gait analysis was repeated 3 weeks and 3, 6, and 12 months after treatment. A classification of toe-walking severity was made before treatment and after 12 months. The parents rated the perceived amount of toe-walking prior to treatment and 6 and 12 months after treatment. Results Eleven children completed the 12-month follow-up. The gait analysis results displayed a significant improvement, indicating decreased plantarflexion angle at initial contact and during swing phase and increased dorsiflexion angle during midstance at all post-treatment testing instances. According to the parents’ perception of toe-walking, 3/11 children followed for 12 months had ceased toe-walking completely, 4/11 decreased toe-walking, and 4/11 continued toe-walking. After 6–12 months, the toe-walking severity classification improved in 9 of the 14 children for whom data could be assessed. Conclusions A single injection of BTX in combination with an exercise program can improve the walking pattern in children with ITW seen at gait analysis, but the obvious goal of ceasing toe-walking is only occasionally reached. PMID:21804891

Gutierrez-Farewik, Elena M.; Bartonek, Åsa; Tedroff, Kristina; Orefelt, Christina; Haglund-Åkerlind, Yvonne

2010-01-01

195

Design of a walking robot  

NASA Technical Reports Server (NTRS)

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

Whittaker, William; Dowling, Kevin

1994-01-01

196

Infinite densities for Lévy walks  

E-print Network

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

Adi Rebenshtok; Sergey Denisov; Peter Hanggi; Eli Barkai

2014-12-01

197

Infinite densities for Lévy walks  

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

198

Persistent random walk with exclusion  

NASA Astrophysics Data System (ADS)

Modelling the propagation of a pulse in a dense milieu poses fundamental challenges at the theoretical and applied levels. To this aim, in this paper we generalize the telegraph equation to non-ideal conditions by extending the concept of persistent random walk to account for spatial exclusion effects. This is achieved by introducing an explicit constraint in the hopping rates, that weights the occupancy of the target sites. We derive the mean-field equations, which display nonlinear terms that are important at high density. We compute the evolution of the mean square displacement (MSD) for pulses belonging to a specific class of spatially symmetric initial conditions. The MSD still displays a transition from ballistic to diffusive behaviour. We derive an analytical formula for the effective velocity of the ballistic stage, which is shown to depend in a nontrivial fashion upon both the density (area) and the shape of the initial pulse. After a density-dependent crossover time, nonlinear terms become negligible and normal diffusive behaviour is recovered at long times.

Galanti, Marta; Fanelli, Duccio; Piazza, Francesco

2013-11-01

199

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

200

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

PubMed

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

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

2014-12-01

201

Velocity-dependent dynamic curvature gain for redirected walking.  

PubMed

Redirected walking techniques allow people to walk in a larger virtual space than the physical extents of the laboratory. We describe two experiments conducted to investigate human sensitivity to walking on a curved path and to validate a new redirected walking technique. In a psychophysical experiment, we found that sensitivity to walking on a curved path was significantly lower for slower walking speeds (radius of 10 m versus 22 m). In an applied study, we investigated the influence of a velocity-dependent dynamic gain controller and an avatar controller on the average distance that participants were able to freely walk before needing to be reoriented. The mean walked distance was significantly greater in the dynamic gain controller condition, as compared to the static controller (22 m versus 15 m). Our results demonstrate that perceptually motivated dynamic redirected walking techniques, in combination with reorientation techniques, allow for unaided exploration of a large virtual city model. PMID:22577150

Neth, Christian T; Souman, Jan L; Engel, David; Kloos, Uwe; Bülthoff, Heinrich H; Mohler, Betty J

2012-07-01

202

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

Microsoft Academic Search

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

Masaki Haruna; Masaki Ogino; Koh Hosoda; Minoru Asada

2001-01-01

203

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

204

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

205

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

PubMed Central

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

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

2007-01-01

206

Kinematic evaluation of virtual walking trajectories.  

PubMed

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

Cirio, Gabriel; Olivier, Anne-Hélène; Marchal, Maud; Pettré, Julien

2013-04-01

207

Quantum Walks on Two Kinds of Two-Dimensional Models  

NASA Astrophysics Data System (ADS)

In this paper, we numerically study quantum walks on two kinds of two-dimensional graphs: cylindrical strip and Mobius strip. The two kinds of graphs are typical two-dimensional topological graph. We study the crossing property of quantum walks on these two models. Also, we study its dependence on the initial state, size of the model. At the same time, we compare the quantum walk and classical walk on these two models to discuss the difference of quantum walk and classical walk.

Li, Dan; Mc Gettrick, Michael; Zhang, Wei-Wei; Zhang, Ke-Jia

2015-01-01

208

Quantum walks on two kinds of two-dimensional models  

E-print Network

In this paper, we numerically study quantum walks on two kinds of two-dimensional graphs: cylindrical strip and Mobius strip. The two kinds of graphs are typical two-dimensional topological graph. We study the crossing property of quantum walks on these two models. Also, we study its dependence on the initial state, size of the model. At the same time, we compare the quantum walk and classical walk on these two models to discuss the difference of quantum walk and classical walk.

Dan Li; Michael Mc Gettrick; Wei-Wei Zhang; Ke-Jia Zhang

2015-01-08

209

Renormalization and Scaling in Quantum Walks  

E-print Network

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

S. Boettcher; S. Falkner; R. Portugal

2014-09-28

210

Walking speed influences on gait cycle variability.  

PubMed

The purpose of this study was to investigate the influence of walking speed on the amount and structure of the stride-to-stride fluctuations of the gait cycle. Based on previous findings for both walking [Hausdorff JM, Purdon PL, Peng CK, Ladin Z, Wei JY, Goldberger AL. Fractal dynamics of human gait: stability of long-range correlations in stride interval fluctuations. J Appl Physiol 1996;80:1448-57], and running [Jordan K, Challis JH, Newell KM. Long range correlations in the stride interval of running. Gait Posture 2006;24:120-5] it was hypothesized that the fractal nature of human locomotion is a reflection of the attractor dynamics of human locomotion. Female participants walked for 12min trials at 80%, 90%, 100%, 110% and 120% of their preferred walking speed. Eight gait cycle variables were investigated: stride interval and length, step interval and length, and from the vertical ground reaction force profile the impulse, first and second peak forces, and the trough force. Detrended fluctuation analysis (DFA) revealed the presence of long range correlations in all gait cycle variables investigated. Speed related U-shaped functions occurred in five of the eight variables, with the minima of these curves falling between 100% and 110% of the preferred walking speed. These findings are consistent with those previously shown in running studies and support the hypothesis that reduced strength of long range correlations at preferred locomotion speeds is reflective of enhanced stability and adaptability at these speeds. PMID:16982195

Jordan, Kimberlee; Challis, John H; Newell, Karl M

2007-06-01

211

Quantum Walk Search through Potential Barriers  

E-print Network

A randomly walking quantum particle searches for a marked vertex on the complete graph of $N$ vertices in Grover's $\\Theta(\\sqrt{N})$ steps. This assumes that the particle can transition from one vertex to another, unhindered. Physically, however, it may need to tunnel through a potential barrier, perhaps due to an imperfect or non-ideal implementation of the walk. Then the particle has some amplitude of correctly hopping and some amplitude of staying put. We show that this causes the search to fail when the particle stays put with amplitude that scales greater than $1/\\sqrt{N}$, so searching larger "databases" requires increasingly reliable hop operations. This condition also holds for search by continuous-time quantum walk.

Thomas G. Wong

2015-03-23

212

Universal quantum computation by discontinuous quantum walk  

SciTech Connect

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

Underwood, Michael S.; Feder, David L. [Institute for Quantum Information Science, University of Calgary, Calgary, Alberta T2N 1N4 (Canada)

2010-10-15

213

Quantum random-walk search algorithm  

SciTech Connect

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

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

2003-05-01

214

Gaussian Networks Generated by Random Walks  

NASA Astrophysics Data System (ADS)

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

Javarone, Marco Alberto

2015-04-01

215

Quantum Walk as a Generalized Measuring Device  

NASA Astrophysics Data System (ADS)

We show that a one-dimensional discrete time quantum walk can be used to implement a generalized measurement in terms of a positive operator value measure (POVM) on a single qubit. More precisely, we show that for a single qubit any set of rank 1 and rank 2 POVM elements can be generated by a properly engineered quantum walk. In such a scenario the measurement of a particle at a position x=i corresponds to a measurement of a POVM element Ei on a qubit. Since the idea of quantum walks originates from the von Neumann model of measurement, in which the change of the position of the pointer depends on the state of the system that is being measured, we argue that von Neumann measurements can be naturally extended to POVMs if one includes the internal evolution of the system in the model.

Kurzy?ski, Pawe?; Wójcik, Antoni

2013-05-01

216

Sensitivity of Quantum Walks with Perturbation  

E-print Network

Quantum computers are susceptible to noises from the outside world. We investigate the effect of perturbation on the hitting time of a quantum walk and the stationary distribution prepared by a quantum walk based algorithm. The perturbation comes from quantizing a transition matrix Q with perturbation E (errors). We bound the perturbed quantum walk hitting time from above by applying Szegedy's work and the perturbation bounds with Weyl's perturbation theorem on classical matrix. Based on an efficient quantum sample preparation approach invented in {\\em speed-up via quantum sampling} and the perturbation bounds for stationary distribution for classical matrix, we find an upper bound for the total variation distance between the prepared quantum sample and the true quantum sample.

Chen-Fu Chiang

2010-07-08

217

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. PMID:22780948

2012-01-01

218

Restoring walking after spinal cord injury.  

PubMed

One of the most obvious deficits following a spinal cord injury is the difficulty in walking, forcing many patients to use wheelchairs for locomotion. Over the past decade considerable effort has been directed at promoting the recovery of walking and to find effective treatments for spinal cord injury. Advances in our knowledge of the neuronal control of walking have led to the development of a promising rehabilitative strategy in patients with partial spinal cord injury, namely treadmill training with partial weight support. The current focus is on developing more efficient training protocols and automating the training to reduce the physical demand for the therapists. Mechanisms underlying training-induced improvements in walking have been revealed to some extent in animal studies. Another strategy for improving the walking in spinal cord injured patients is the use of functional electric stimulation of nerves and muscles to assist stepping movements. This field has advanced significantly over the past decade as a result of developments in computer technology and the miniaturization of electronics. Finally, basic research on animals with damaged spinal cords has focused on enhancing walking and other motor functions by promoting growth and regeneration of damaged axons. Numerous important findings have been reported yielding optimism that techniques for repairing the injured spinal cord will be developed in the near future. However, at present no strategy involving direct treatment of the injured spinal cord has been established for routine use in spinal cord injured patients. It now seems likely that any successful protocol in humans will require a combination of a treatment to promote re-establishing functional connections to neuronal networks in the spinal cord and specialized rehabilitation training to shape the motor patterns generated by these networks for specific behavioral tasks. PMID:15201036

Fouad, Karim; Pearson, Keir

2004-06-01

219

A model of muscle-tendon function in human walking  

E-print Network

In order to motivate the design of legged machines that walk as humans do, this thesis investigates how leg muscles and tendons work mechanically during level-ground human walking at self-selected speeds. I hypothesize ...

Endo, Ken, Ph. D. Massachusetts Institute of Technology

2012-01-01

220

Modified discrete random walk with absorption  

E-print Network

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

Theo van Uem

2009-03-02

221

Adaptive Walks and Extreme Value Theory  

NASA Astrophysics Data System (ADS)

We study biological evolution in a high-dimensional genotype space in the regime of rare mutations and strong selection. The population performs an uphill walk which terminates at local fitness maxima. Assigning fitness randomly to genotypes, we show that the mean walk length is logarithmic in the number of initially available beneficial mutations, with a prefactor determined by the tail of the fitness distribution. This result is derived analytically in a simplified setting where the mutational neighborhood is fixed during the adaptive process, and confirmed by numerical simulations.

Neidhart, Johannes; Krug, Joachim

2011-10-01

222

7.RP Walk-a-thon 2  

NSDL National Science Digital Library

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

2013-07-07

223

6.RP Walk-a-thon 1  

NSDL National Science Digital Library

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

224

Self-Avoiding Walks with Writhe  

E-print Network

We map self-avoiding random walks with a chemical potential for writhe to the three-dimensional complex O(N) Chern-Simons theory as N -> 0. We argue that at the Wilson-Fisher fixed point which characterizes normal self-avoiding walks (with radius of gyration exponent nu = 0.588) a small chemical potential for writhe is irrelevant and the Chern-Simons field does not modify the monomer- monomer correlation function. For a large chemical potential the polymer collapses.

J. David Moroz; Randall D. Kamien

1997-05-11

225

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

PubMed Central

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

2012-01-01

226

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

227

Continuous-time quantum walks on star graphs  

SciTech Connect

In this paper, we investigate continuous-time quantum walk on star graphs. It is shown that quantum central limit theorem for a continuous-time quantum walk on star graphs for N-fold star power graph, which are invariant under the quantum component of adjacency matrix, converges to continuous-time quantum walk on K{sub 2} graphs (complete graph with two vertices) and the probability of observing walk tends to the uniform distribution.

Salimi, S. [Department of Physics, University of Kurdistan, P.O. Box 66177-15175, Sanandaj (Iran, Islamic Republic of)], E-mail: shsalimi@uok.ac.ir

2009-06-15

228

Limit theorems and absorption problems for one-dimensional correlated random walks  

E-print Network

There has recently been considerable interest in quantum walks in connection with quantum computing. The walk can be considered as a quantum version of the so-called correlated random walk. We clarify a strong structural similarity between both walks and study limit theorems and absorption problems for correlated random walks by our PQRS method, which was used in our analysis of quantum walks.

Norio Konno

2010-06-06

229

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.

EDC in Maine

2012-01-01

230

Quantum walk based search algorithms Miklos Santha1,2  

E-print Network

]. The relevance of finite Markov chains (random walks in graphs) to searching was recognized from early onQuantum walk based search algorithms Miklos Santha1,2 1 CNRS­LRI, Universit´e Paris­Sud, 91405. Grover search and the quantum walk based search algorithms of Ambainis, Szegedy and Magniez et al

Fondements et Applications, Université Paris 7

231

The 'passive dynamic walking machine' used in the experiments.  

E-print Network

The 'passive dynamic walking machine' used in the experiments. Credit: University of Michigan with 'passive dynamic machines', which walk down a small incline without any power source, as well as robots, "arm swinging appears to arise from the natural dynamics, or passive dynamics, of the body as it walks

Collins, Steven H.

232

Passive\\/active unified dynamic walking for biped locomotion  

Microsoft Academic Search

In order to implement walking efficiency and environmental adapting ability to a biped locomotion, it is required to combine passive dynamic walking and active one. In this paper, a passive\\/active unified dynamic walking for biped locomotion was proposed. Firstly, a passive\\/active unified actuator that has a torque detector and is actively controlled by zero torque feedback control was proposed and

Qingjiu Huang; Takamasa Hase; Kyosuke Ono

2007-01-01

233

Walking Robotics The Cornell Ranger Fall 2006 Semester Report  

E-print Network

in the Cornell Walking Robotics laboratory are developing passive-dynamic robots. Such a different designWalking Robotics ­ The Cornell Ranger Fall 2006 Semester Report Alexander Gates Sophomore, Cornell in the Ranger. Using these components, the Cornell Ranger recently set a distance record for walking robots

Ruina, Andy L.

234

NON-PERTURBATIVE APPROACH TO RANDOM WALK IN MARKOVIAN ENVIRONMENT.  

E-print Network

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

Liverani, Carlangelo

235

Evaluation of Reorientation Techniques for Walking in Large Virtual Environments  

E-print Network

Evaluation of Reorientation Techniques for Walking in Large Virtual Environments Tabitha C. Peck a real-walking locomotion in- terface have typically been restricted in size to the area of the tracked lab space. Techniques proposed to lift this size constraint, enabling real walking in VEs

North Carolina at Chapel Hill, University of

236

Evaluation of Reorientation Techniques and Distractors for Walking in  

E-print Network

VEs and each method suggests its own ROT to enable free exploration. Redirected walking [5], [6], [7Evaluation of Reorientation Techniques and Distractors for Walking in Large Virtual Environments Abstract--Virtual Environments (VEs) that use a real-walking locomotion interface have typically been

Whitton, Mary C.

237

Walking after spinal cord injury: Evaluation, treatment, and functional recovery  

Microsoft Academic Search

Objective: To present some recent developments and concepts emerging from both animal and human studies aimed at enhancing recovery of walking after spinal cord injury (SCI).Data Sources: Researchers in the field of restoration of walking after SCI, as well as references extracted from searches in the Medline computerized database.Study Selection: Studies that reported outcome measures of walking for spinal cord

Hugues Barbeau; Michel Ladouceur; Kathleen E. Norman; André Pépin; Alain Leroux

1999-01-01

238

An Adapting Random Walk for Ad Hoc and Sensor Networks  

Microsoft Academic Search

In this paper we propose an adaptive random walk for wireless networks. The lifetime of the walk is varied in such a way that at least a given fraction of nodes is covered, in expectation. The only parameter of the random walk, ?, depends on the nominal network size N and on the required coverage. For sizes lower than N

Adnan Noor Mian; Roberto Baldoni; Roberto Beraldi

2009-01-01

239

A random walk based algorithm for structural test case generation  

Microsoft Academic Search

Structural testing is a significant and expensive process in software development. By converting test data generation into an optimization problem, search-based software testing is one of the key technologies of automated test case generation. Motivated by the success of random walk in solving the satisfiability problem (SAT), we proposed a random walk based algorithm (WalkTest) to solve structural test case

Jifeng Xuan; He Jiang; Zhilei Ren; Yan Hu; Zhongxuan Luo

2010-01-01

240

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 effective…

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

2002-01-01

241

Modeling and Learning Walking Gaits of Biped Robots  

E-print Network

out by doing walk evolution with different configurations of the strategy in a robot simulator. Finally the best performing strategy is used to evolve a forward walk on a real robot. I. INTRODUCTION. For these experiments we have developed a system which allows the robot to learn to walk fully autonomously. II

Menegatti, Emanuele

242

The Not-so-Random Drunkard's Walk  

ERIC Educational Resources Information Center

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

Ehrhardt, George

2013-01-01

243

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

Code of Federal Regulations, 2013 CFR

...walk-in freezer that are not part of its refrigeration system. K-factor means the thermal...including, but not limited to, refrigeration, doors, lights, windows, or walls...below 55 degrees Fahrenheit using a refrigeration system. Refrigeration...

2013-01-01

244

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

Code of Federal Regulations, 2012 CFR

...walk-in freezer that are not part of its refrigeration system. K-factor means the thermal...including, but not limited to, refrigeration, doors, lights, windows, or walls...below 55 degrees Fahrenheit using a refrigeration system. Refrigeration...

2012-01-01

245

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

Code of Federal Regulations, 2014 CFR

...walk-in freezer that are not part of its refrigeration system. K-factor means the thermal...including, but not limited to, refrigeration, doors, lights, windows, or walls...below 55 degrees Fahrenheit using a refrigeration system. Refrigeration...

2014-01-01

246

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

E-print Network

walk patterns commonly observed in animals such as mon- keys, birds and jackals. Our study is based), jackals or even highly charged electron particles. What all these have in common is that their mobility

Young, R. Michael

247

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

SciTech Connect

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

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

2010-06-15

248

Dynamic arm swinging in human walking.  

PubMed

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

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

2009-10-22

249

The physics of a walking robot  

E-print Network

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

Güémez, Julio

2014-01-01

250

Random Walk Method for Potential Problems  

NASA Technical Reports Server (NTRS)

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

Krishnamurthy, T.; Raju, I. S.

2002-01-01

251

RANDOM WALKS FOR INTERACTIVE ALPHA-MATTING  

Microsoft Academic Search

Interactive, efficient, methods of foreground extraction a nd alpha-matting are of increasing practical importance for digital image editing. Although several new approaches to this problem have recently been developed, many chal- lenges remain. We propose a new technique based on ran- dom walks that has the following advantages: First, by leveraging a recent technique from manifold learning the- ory, we

Leo Grady; Thomas Schiwietz; Shmuel Aharon; Rudiger Westermann

2005-01-01

252

Solving convex programs by random walks  

Microsoft Academic Search

Minimizing a convex function over a convex set in n-dimensional space is a basic, general problem with many interesting special cases. Here, we present a simple new algorithm for convex optimization based on sampling by a random walk. It extends naturally to minimizing quasi-convex functions and to other generalizations.

Dimitris Bertsimas; Santosh Vempala

2004-01-01

253

Robust Variance Reduction for Random Walk Methods  

Microsoft Academic Search

Random walk methods are effective for solving linear partial differential equations in many dimensions, especially those involving complex geometries. They are based on an equivalence given by a Feynman-Kac formula between an expectation of a functional of a stochastic process and the solution at a point of a partial differential equation. The drawback is that the error is proportional only

Gang Zou; Robert D. Skeel

2004-01-01

254

Levy walk evolution for global optimization  

Microsoft Academic Search

A novel evolutionary global optimization approach based on adaptive covariance estimation is proposed. The proposed method samples from a multivariate Levy Skew Alpha-Stable distribution with the estimated covariance matrix to realize a random walk and so to generate new solution candidates in the mutation step. The proposed method is compared to the popular Differential Evolution method, which is one of

Onay Urfalioglu; A. Enis Çetin; Ercan Engin Kuruoglu

2008-01-01

255

Optimal Switching Between Two Random Walks  

Microsoft Academic Search

This paper is motivated by remarkable results of Mandelbaum, Shepp and Vanderbei concerning an optimal switching problem for two Brownian motions. In this paper, the discrete form of this problem, in which the Brownian motions are replaced by random walks, is studied and solved without any restriction on the boundary data. The method proposed here involves uncovering the structure of

R. Cairoli; Robert C. Dalang

1995-01-01

256

Conditioning SLEs and loop erased random walks  

E-print Network

We discuss properties of dipolar SLE(k) under conditioning. We show that k=2, which describes continuum limits of loop erased random walks, is characterized as being the only value of k such that dipolar SLE conditioned to stop on an interval coincides with dipolar SLE on that interval. We illustrate this property by computing a new bulk passage probability for SLE(2).

Michel Bauer; Denis Bernard; Tom Kennedy

2008-06-13

257

Random walk centrality for temporal networks  

NASA Astrophysics Data System (ADS)

Nodes can be ranked according to their relative importance within a network. Ranking algorithms based on random walks are particularly useful because they connect topological and diffusive properties of the network. Previous methods based on random walks, for example the PageRank, have focused on static structures. However, several realistic networks are indeed dynamic, meaning that their structure changes in time. In this paper, we propose a centrality measure for temporal networks based on random walks under periodic boundary conditions that we call TempoRank. It is known that, in static networks, the stationary density of the random walk is proportional to the degree or the strength of a node. In contrast, we find that, in temporal networks, the stationary density is proportional to the in-strength of the so-called effective network, a weighted and directed network explicitly constructed from the original sequence of transition matrices. The stationary density also depends on the sojourn probability q, which regulates the tendency of the walker to stay in the node, and on the temporal resolution of the data. We apply our method to human interaction networks and show that although it is important for a node to be connected to another node with many random walkers (one of the principles of the PageRank) at the right moment, this effect is negligible in practice when the time order of link activation is included.

Rocha, Luis E. C.; Masuda, Naoki

2014-06-01

258

A Smart Walker to Understand Walking Abilities  

E-print Network

· No standardized procedure · Common clinical measures: ­ Timed Up and Go (TUG) ­ Berg Balance Scale (BBS) ­ Center is balance control affected? ­ What are the challenges? · Can we assess walking abilities in a naturalistic to decrease performance #12;15 Lower Limb Balance Control #12;16 Upper Limb Balance Control · Center

Poupart, Pascal

259

Time dependency of walking classification in stroke  

Microsoft Academic Search

BACKGROUND AND PURPOSE: To facilitate optimal stroke rehabilitation, valid interpretation of observed functional recovery is required. The purpose of this study was to examine the longitudinal relationship between comfortable walking speed and Functional Ambulation Categories (FAC) scores for physically independent gait. SUBJECTS: This study was a prospective cohort study with 73 subjects who were severely affected by acute stroke. METHODS:

B. Kollen; G. Kwakkel; E. Lindeman

2006-01-01

260

Cavity QED-based quantum walk  

E-print Network

We discuss a possible experimental scheme for the implementation of a quantum walk. The scheme is based on the passage of an atom inside a high-Q cavity. The chirality is characterized by the atomic states and the displacement is characterized...

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

2004-01-01

261

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

262

Take a Hike!: A Family Forest Walk  

NSDL National Science Digital Library

In this family or group inquiry activity, learners use their senses to explore a local forest or woodland. Learners can look for decomposers and fungi, investigate flowers and pollination, and practice observation skills while looking for signs of plant and animal life interaction. Learners will sketch their findings in a nature journal and then share their observations after the forest walk.

Smithsonian National Zoological Park

2012-06-26

263

Mixing of Quantum Walk on Circulant Bunkbeds  

E-print Network

We give new observations on the mixing dynamics of a continuous-time quantum walk on circulants and their bunkbed extensions. These bunkbeds are defined through two standard graph operators: the join G + H and the Cartesian product of graphs G and H.Our results include the following: 1. The quantum walk is average uniform mixing on circulants with bounded eigenvalue multiplicity. This extends a known fact about the cycles. 2. Explicit analysis of the probability distribution of the quantum walk on the join of circulants. This explains why complete partite graphs are not average uniform mixing, using the fact the complete n-vertex graph is the join of a 1-vertex graph and the (n-1)-vertex complete graph, and that the complete m-partite graph, where each partition has size n, is the m-fold join of the empty n-vertex graph. 3. The quantum walk on the Cartesian product of a m-vertex path P and a circulant G, is average uniform mixing if G is. This highlights a difference between circulants and the hypercubes. Our proofs employ purely elementary arguments based on the spectra of the graphs.

P. Lo; S. Rajaram; D. Schepens; D. Sullivan; C. Tamon; J. Ward

2005-09-08

264

RESEARCH ARTICLE Water-walking devices  

E-print Network

-inspired tape (Geim et al. 2003) to a dolphin-skin-inspired torpedo shell (Fish 2006). Biomimetic robots are now us about innovative, optimal and versatile designs. Since its inception, biomimetics has grown built biomimetic water-walking devices. Water-walkers can be classified as large or small according

Bush, John W.M.

265

Logical Characterization of Weighted Pebble Walking Automata  

E-print Network

than words, such as graphs. To address this drawback, weighted automata have recently been generalized classes of graphs, including all the aforementioned classes. 1 Introduction Automata are a universal tool states that Boolean (nondeterministic) pebble graph-walking automata have the same expressive power

Bollig, Benedikt

266

Anterior tibial compartment pressure during race walking  

Microsoft Academic Search

In 14 race walkers the intramuscular pressure in the anterior tibial muscle was measured with a wick cath eter. At rest the pressure was 10 to 15 mmHg and increased by a factor of 10 during full speed walking. Those walkers who experienced pain in the anterior tibial muscle also had a higher than average pressure. Fasciotomy decreased the intramuscular

Lennart Sanzen; Artur Forsberg; Nils Westlin

1986-01-01

267

Saccadic body turns in walking Drosophila  

PubMed Central

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

Geurten, Bart R. H.; Jähde, Philipp; Corthals, Kristina; Göpfert, Martin C.

2014-01-01

268

The Physics of a Walking Robot  

ERIC Educational Resources Information Center

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

Guemez, J.; Fiolhais, M.

2013-01-01

269

Measurements in the Levy quantum walk  

SciTech Connect

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

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

2007-11-15

270

Non-homogeneous random walks Andrew Wade  

E-print Network

, who explained why the sky is blue (Rayleigh scattering). . . #12;Karl Pearson · Pearson published (University of Campinas) #12;1 Talk outline 2 Classical (spatially homogeneous) random walks Model 1: Pearson more recent work with my collaborators I. MacPhee and M. Menshikov (University of Durham). #12;Karl

Wirosoetisno, Djoko

271

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

272

Coyote Walking Through Post-Wildfires  

USGS Multimedia Gallery

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

273

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

274

Walk Across Texas! and Texas Education Agency  

E-print Network

ranks 7th as the state with the highest childhood overweight rates. · Higher levels of fitness, and medications. · Community-wide programs like Walk Across Texas! have been strongly associated with significant Management Texas A&M AgriLife Extension Service ph. 979.845.3850 fx. 979.845.6496 http

275

Toolbox Safety Talk Walking/Working Surfaces  

E-print Network

such as ice, standing water, grease, polished floors, loose flooring or carpeting, uneven walking surfaces that could create a hazard. Guardrail Systems Guardrail systems consist of a top rail 42 inches high and must and must withstand 50 pounds. Floor Loading Protection Whenever loads or single items exceeding 350lbs

Pawlowski, Wojtek

276

Teachers as Walk-Through Partners  

ERIC Educational Resources Information Center

As a high school principal, the author came to realize that the traditional teacher observation and evaluation model did not help teachers become reflective and improve their practice. Because his own use of brief, frequent principal walk-throughs had given him valuable insights into the need for instructional improvements, he decided to offer…

Bushman, James

2006-01-01

277

RANDOM WALKS ON NILPOTENT GROUPS Alexander Astashkevich  

E-print Network

groups, with Hall bases as generating sets. Introduction In the past two decades, the study [D1,DF]). At the same time, despite several attempts, ra* *n- dom walks on finite simple groups1]. The generating sets we consider are the `Hall bases', which extend the notion

Pak, Igor

278

RANDOM WALKS ON NILPOTENT GROUPS Alexander Astashkevich  

E-print Network

on nilpotent groups, with Hall bases as generating sets. Introduction In the past two decades, the study [D1,DF]). At the same time, despite several attempts, ran- dom walks on #12;nite simple groups remain]. The generating sets we consider are the `Hall bases', which extend the notion of the power commutator generating

Pak, Igor

279

RANDOM WALKS ON NILPOTENT GROUPS Alexander Astashkevich  

E-print Network

on nilpotent groups, with Hall bases as generating sets. Introduction In the past two decades, the study]). At the same time, despite several attempts, ran- dom walks on finite simple groups remain `terra incognita certain assumptions, most of the sets of generators of size O(log |G|) mix in time O(log |G|) (see

Pak, Igor

280

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

281

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

282

Consumer preference in ranking walking function utilizing the walking index for spinal cord injury II  

Microsoft Academic Search

Study design:Blinded rank ordering.Objective:To determine consumer preference in walking function utilizing the walkingIndex for spinal cord injury II (WISCI II) in individuals with spinal cord injury (SCI)from the Canada, the Italy and the United States of America.Method:In all, 42 consumers with incomplete SCI (25 cervical, 12 thoracic, 5 lumbar) from Canada (12\\/42), Italy (14\\/42) and the United States of America

M Patrick; P Ditunno; J F Ditunno; R J Marino; G Scivoletto; T Lam; J Loffree; F Tamburella; B Leiby

2011-01-01

283

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 2-km…

Kamien, Dorota

2008-01-01

284

Relationships between muscle contributions to walking subtasks and functional walking status in persons with post-stroke hemiparesis  

E-print Network

: Contributions from the paretic leg muscles (i.e., soleus, gastrocnemius and gluteus medius) to forwardRelationships between muscle contributions to walking subtasks and functional walking status Gait Muscle function Background: Persons with post-stroke hemiparesis usually walk slowly

285

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

PubMed Central

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

Nagano, Katsuhito; Hori, Hideaki; Muramatsu, Ken

2015-01-01

286

Comparison of elliptical training, stationary cycling, treadmill walking and overground walking  

PubMed Central

The most common functional motor goal of lower extremity rehabilitation is to improve walking ability. For reasons of feasibility, safety or intensity, devices are frequently used to facilitate or augment gait training. The objective of this study was to compare the muscle activity patterns of the quadriceps and hamstring muscles during four conditions: overground walking, treadmill walking, stationary cycling, and elliptical training. Ten healthy adults (6 male, 4 female; mean age 22.7 ± 2.9 yrs, range 20–29) participated. Surface electromyographic data were recorded from the rectus femoris and semitendinosus. Linear envelope curves were generated and time normalized from 0–100% cycle. The mean plus three standard deviations from a static trial was used as the threshold for muscle activity. Repeated measures analysis of variance procedures were used to detect differences between conditions. Elliptical training demonstrated greater quadriceps activity and greater quadriceps/hamstrings coactivation than all other conditions. Consistent with previous work, treadmill walking demonstrated greater quadriceps activity than overground walking. Minimal differences in hamstring activation were observed between conditions, limited to lower peak activity during cycling compared to treadmill walking. These results provide normative values for quadriceps and hamstring activation for different locomotor training methods and may assist in selecting the most appropriate training device for specific patients. Clinicians and researchers should also consider the kinematic and kinetic differences between tasks, which cannot necessarily be inferred from muscle activation patterns. PMID:21215636

Prosser, Laura A.; Stanley, Christopher J.; Norman, Tracy L.; Park, Hyung S.; Damiano, Diane L.

2012-01-01

287

Complexity analysis of quantum walk based search algorithms  

E-print Network

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

B. L. Douglas; J. B. Wang

2014-08-07

288

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

289

Universal quantum computation using the discrete time quantum walk  

E-print Network

A proof that continuous time quantum walks are universal for quantum computation, using unweighted graphs of low degree, has recently been presented by Childs [PRL 102 180501 (2009)]. We present a version based instead on the discrete time quantum walk. We show 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.

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

2010-03-02

290

Scaling of the atmosphere of self-avoiding walks  

E-print Network

The number of free sites next to the end of a self-avoiding walk is known as the atmosphere. The average atmosphere can be related to the number of configurations. Here we study the distribution of atmospheres as a function of length and how the number of walks of fixed atmosphere scale. Certain bounds on these numbers can be proved. We use Monte Carlo estimates to verify our conjectures. Of particular interest are walks that have zero atmosphere, which are known as trapped. We demonstrate that these walks scale in the same way as the full set of self-avoiding walks, barring an overall constant factor.

A. L. Owczarek; T. Prellberg

2008-06-06

291

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.

Uri Wilensky

292

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. PMID:23606966

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

2013-01-01

293

Finding edge permutations in a graph using quantum walks  

NASA Astrophysics Data System (ADS)

The problem of graph structure discovery is important in many fields of science. Quantum walks are expected to bring significant algorithmic improvements to quantum computing. More generally, random walks (Markov chains on graphs) can be very useful as a different approach to problems. We use a specific quantum walk to address unknown permutations in a graph. Consider two matching graphs, with unknown permutations of edges that connect them. For example: a vertex on the left is connected to a set of vertices to its right; on the far right is another vertex, connected to another set of nodes, to its left. These two sets of nodes are connected in the middle, but we do not know which left nodes connect to which right ones. We construct a quantum walk on such a graph structure that allows us to gain a surprising amount of information, or completely determine permutations, often in a single pass over the graph. We detect classes of interesting properties of our walk on such unknown graphs. Classical walks cannot resolve some cases at all, implying a formally "infinite" speed up. This walk is an example of use of our recent framework for building quantum walks, based on classical walks with memory. The framework contains all major known walks, while it can also build walks on structures prohibitively difficult for current techniques.

Dimcovic, Zlatko; Kovchegov, Yevgeniy

2011-03-01

294

Generalized atmospheric sampling of self-avoiding walks  

NASA Astrophysics Data System (ADS)

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

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

2009-08-01

295

Numerical Simulations of Level-Ground Walking Based on Passive Walk for Planar Biped Robots with Torso by Hip Actuators  

NASA Astrophysics Data System (ADS)

This study aims at a design technique of energy-efficient biped walking robots on level ground with simple mechanisms. To do this, we focus on the passive dynamic walkers which can walk stably down a shallow slope without actuators and controllers. On level ground, active walking should be studied because the mechanical energy is mainly lost through the swing-leg impacts with the ground. In this paper, numerical simulations show that planar biped robots with torso can walk efficiently on level ground over a wide range of speed by only using hip actuators. The hip actuators are used for a torso and swing-leg control based on passive-dynamic walking. The torso is used to generate active power replacing gravity used in the case of the passive walk. The swing-leg control is introduced to walk stably over a wide range of speed.

Narukawa, Terumasa; Takahashi, Masaki; Yoshida, Kazuo

296

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

PubMed

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

Degeling, Chris; Rock, Melanie

2013-09-01

297

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

PubMed

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

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

2013-01-01

298

Energy cost of balance control during walking decreases with external stabilizer stiffness independent of walking speed.  

PubMed

Human walking requires active neuromuscular control to ensure stability in the lateral direction, which inflicts a certain metabolic load. The magnitude of this metabolic load has previously been investigated by means of passive external lateral stabilization via spring-like cords. In the present study, we applied this method to test two hypotheses: (1) the effect of external stabilization on energy cost depends on the stiffness of the stabilizing springs, and (2) the energy cost for balance control, and consequently the effect of external stabilization on energy cost, depends on walking speed. Fourteen healthy young adults walked on a motor driven treadmill without stabilization and with stabilization with four different spring stiffnesses (between 760 and 1820 Nm(-1)) at three walking speeds (70%, 100%, and 130% of preferred speed). Energy cost was calculated from breath-by-breath oxygen consumption. Gait parameters (mean and variability of step width and stride length, and variability of trunk accelerations) were calculated from kinematic data. On average external stabilization led to a decrease in energy cost of 6% (p<0.005) as well as a decrease in step width (24%; p<0.001), step width variability (41%; p<0.001) and variability of medio-lateral trunk acceleration (12.5%; p<0.005). Increasing stabilizer stiffness increased the effects on both energy cost and medio-lateral gait parameters up to a stiffness of 1260 Nm(-1). Contrary to expectations, the effect of stabilization was independent of walking speed (p=0.111). These results show that active lateral stabilization during walking involves an energetic cost, which is independent of walking speed. PMID:23895896

Ijmker, Trienke; Houdijk, Han; Lamoth, Claudine J C; Beek, Peter J; van der Woude, Lucas H V

2013-09-01

299

Quantum Parrondo's games using quantum walks  

E-print Network

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

Adrian P. Flitney

2012-09-11

300

Random Walk Picture of Basketball Scoring  

E-print Network

We present evidence, based on play-by-play data from all 6087 games from the 2006/07--2009/10 seasons of the National Basketball Association (NBA), that basketball scoring is well described by a weakly-biased continuous-time random walk. The time between successive scoring events follows an exponential distribution, with little memory between different scoring intervals. Using this random-walk picture that is augmented by features idiosyncratic to basketball, 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. By further including the heterogeneity of team strengths, we build a computational model that accounts for essentially all statistical features of game scoring data and season win/loss records of each team.

Gabel, Alan

2011-01-01

301

Quantum walks with memory - goldfish, elephants and wise old men  

E-print Network

Quantum walks have emerged as an interesting approach to quantum information processing, exhibiting many unique properties compared to the analogous classical random walk. Here we introduce a model for a discrete-time quantum walk with memory by endowing the walker with multiple recycled coins and using a physical memory function via a history dependent coin flip. By numerical simulation we observe several phenomena. First in one dimension, walkers with memory have persistent quantum ballistic speed up over classical walks just as found in previous studies of multi-coined walks with trivial memory function. However, measurement of the multi-coin state can dramatically shift the mean of the spatial distribution. Second, we consider spatial entanglement in a two-dimensional quantum walk with memory and find that memory destroys entanglement between the spatial dimensions, even when entangling coins are employed. Finally, we explore behaviour in the presence of spatial randomness and find that in contrast to single coined walks, multi-coined walks do not localise and in fact a memory function can speed up the walk relative to a fully decohered multi-coin walker with trivial memory. We explicitly show how to construct linear optics circuits implementing the walks, and discuss prospects for classical simulation.

Peter P. Rohde; Gavin K. Brennen; Alexei Gilchrist

2012-12-18

302

Community walking programs for treatment of peripheral artery disease  

PubMed Central

Background Supervised walking programs offered at medical facilities for patients with peripheral artery disease (PAD) and intermittent claudication (IC), while effective, are often not utilized due to barriers including lack of reimbursement and the need to travel to specialized locations for the training intervention. Walking programs for PAD patients that occur in community settings, such as those outside of supervised settings, may be a viable treatment option, as they are convenient and potentially bypass the need for supervised walking. This review evaluated the various methodologies and outcomes of community walking programs for PAD. Methods A literature review using appropriate search terms was conducted within PubMed/Medline and the Cochrane databases to identify studies in the English language employing community walking programs to treat PAD patients with IC. Search results were reviewed, and relevant articles were identified that form the basis of this review. The primary outcome was peak walking performance on the treadmill. Results Randomized controlled trials (n=10) examining peak walking outcomes in 558 PAD patients demonstrated that supervised exercise programs were more effective than community walking studies that consisted of general recommendations for patients with IC to walk at home. Recent community trials that incorporated more advice and feedback for PAD patients in general resulted in similar outcomes with no differences in peak walking time compared to supervised walking exercise groups. Conclusions Unstructured recommendations for patients with symptomatic PAD to exercise in the community are not efficacious. Community walking programs with more feedback and monitoring offer improvements in walking performance for patients with claudication and may bypass some obstacles associated with facility-based exercise programs. PMID:24103409

Mays, Ryan J.; Rogers, R. Kevin; Hiatt, William R.; Regensteiner, Judith G.

2013-01-01

303

Multiple-Instance Learning Via Random Walk  

Microsoft Academic Search

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

Dong Wang; Jianmin Li; Bo Zhang

2006-01-01

304

Reweighted Random Walks for Graph Matching  

Microsoft Academic Search

\\u000a Graph matching is an essential problem in computer vision and machine learning. In this paper, we introduce a random walk\\u000a view on the problem and propose a robust graph matching algorithm against outliers and deformation. Matching between two graphs\\u000a is formulated as node selection on an association graph whose nodes represent candidate correspondences between the two graphs.\\u000a The solution is

Minsu Cho; Jungmin Lee; Kyoung Mu Lee

2010-01-01

305

A random walk approach to quantum algorithms  

Microsoft Academic Search

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

Vivien M. Kendon

2006-01-01

306

Colorization Using Segmentation with Random Walk  

Microsoft Academic Search

Traditional monochrome image colorization techniques require considerable user interaction and a lot of time. The segment-based\\u000a colorization works fast but at the expense of detail loss because of the large segmentation; while the optimization based\\u000a method looks much more continuous but takes longer time. This paper proposed a novel approach: Segmentation colorization based\\u000a on random walks, which is a fast

Xiaoming Liu; Jun Liu; Zhilin Feng

2009-01-01

307

Walking Habits of Adults with Mental Retardation  

ERIC Educational Resources Information Center

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

Stanish, Heidi I.; Draheim, Christopher C.

2005-01-01

308

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

309

Baby Carriage: Infants Walking With Loads  

Microsoft Academic Search

Maintaining balance is a central problem for new walkers. To examine how infants cope with the additional balance control problems induced by load carriage, 14-month-olds were loaded with 15% of their body weight in shoulder-packs. Both symmetrical and asymmetrical loads disrupted alternating gait patterns and caused less mature footfall patterns. Walking was most severely compromised by back loads. Infants with

Jessie S. Garciaguirre; Karen E. Adolph; Patrick E. Shrout

2007-01-01

310

Head-bobbing of walking birds  

Microsoft Academic Search

Many birds show a rhythmic forward and backward movement of their heads when they walk on the ground. This so-called “head-bobbing”\\u000a is characterized by a rapid forward movement (thrust phase) which is followed by a phase where the head keeps its position\\u000a with regard to the environment but moves backward with regard to the body (hold phase). These head movements

Reinhold Necker

2007-01-01

311

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. PMID:21267424

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

2010-01-01

312

Gait recognition and walking exercise intensity estimation.  

PubMed

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

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

2014-04-01

313

Walking simulator for evaluation of ophthalmic devices  

NASA Astrophysics Data System (ADS)

Simulating mobility tasks in a virtual environment reduces risk for research subjects, and allows for improved experimental control and measurement. We are currently using a simulated shopping mall environment (where subjects walk on a treadmill in front of a large projected video display) to evaluate a number of ophthalmic devices developed at the Schepens Eye Research Institute for people with vision impairment, particularly visual field defects. We have conducted experiments to study subject's perception of "safe passing distance" when walking towards stationary obstacles. The subject's binary responses about potential collisions are analyzed by fitting a psychometric function, which gives an estimate of the subject's perceived safe passing distance, and the variability of subject responses. The system also enables simulations of visual field defects using head and eye tracking, enabling better understanding of the impact of visual field loss. Technical infrastructure for our simulated walking environment includes a custom eye and head tracking system, a gait feedback system to adjust treadmill speed, and a handheld 3-D pointing device. Images are generated by a graphics workstation, which contains a model with photographs of storefronts from an actual shopping mall, where concurrent validation experiments are being conducted.

Barabas, James; Woods, Russell L.; Peli, Eli

2005-03-01

314

Gait Recognition and Walking Exercise Intensity Estimation  

PubMed Central

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

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

2014-01-01

315

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

316

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

PubMed Central

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

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

2013-01-01

317

Walking trajectory control of a biped robot Technical report B-04-18  

E-print Network

] developed a passive biped robot to study dynamic walking. The robot can settle a stable gait without robot walking is the instability produced by the violent transition between the different dynamic walk in static walking for not structured terrain. Kajita [2] studied the control of the dynamic walking

Rojas, Raúl

318

AutoGait: A mobile platform that accurately estimates the distance walked  

Microsoft Academic Search

AutoGait is a mobile platform that autonomously discovers a user's walking profile and accurately estimates the distance walked. The discovery is made by utilizing the GPS in the user's mobile device when the user is walking outdoors. This profile can then be used both indoors and outdoors to estimate the distance walked. To model the person's walking profile, we take

Dae-Ki Cho; Min Mun; Uichin Lee; Williams J. Kaiser; Mario Gerla

2010-01-01

319

Walk, Not Wait: Faster Sampling Over Online Social Networks  

E-print Network

In this paper, we introduce a novel, general purpose, technique for faster sampling of nodes over an online social network. Specifically, unlike traditional random walk which wait for the convergence of sampling distribution to a predetermined target distribution - a waiting process that incurs a high query cost - we develop WALK-ESTIMATE, which starts with a much shorter random walk, and then proactively estimate the sampling probability for the node taken before using acceptance-rejection sampling to adjust the sampling probability to the predetermined target distribution. We present a novel backward random walk technique which provides provably unbiased estimations for the sampling probability, and demonstrate the superiority of WALK-ESTIMATE over traditional random walks through theoretical analysis and extensive experiments over real world online social networks.

Nazi, Azade; Thirumuruganathan, Saravanan; Zhang, Nan; Das, Gautam

2014-01-01

320

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

321

Finding structural anomalies in star graphs using quantum walks.  

PubMed

We develop a general theory for a quantum-walk search on a star graph. A star graph has N edges each of which is attached to a central vertex. A graph G is attached to one of these edges, and we would like to find out to which edge it is attached. This is done by means of a quantum walk, a quantum version of a random walk. This walk contains O(sqrt[N]) steps, which represents a speedup over a classical search, which would require O(N) steps. The overall graph, star plus G, is divided into two parts, and we find that for a quantum speedup to occur, the eigenvalues associated with these two parts in the N?? limit must be the same. Our theory tells us how the initial state of the walk should be chosen, and how many steps the walk must make in order to find G. PMID:24484125

Cottrell, Seth; Hillery, Mark

2014-01-24

322

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

PubMed

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

Srinivasan, Manoj

2009-06-01

323

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

NASA Astrophysics Data System (ADS)

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

Srinivasan, Manoj

2009-06-01

324

Exact solutions for restricted walks with applications to polymers  

NASA Astrophysics Data System (ADS)

The combinatorial theory of runs is used to algebraically enumerate new classes of restricted random walks and restricted self-avoiding walks. The restrictions favour the local formation of either cis or trans configurations. Exact results are derived and presented for the connective constant and corresponding exponent value for walks on d-dimensional hypercubic lattices. Preliminary numerical results for the mean square end-to-end distance exponent are also given.

Batchelor, M. T.; Henry, B. I.

1991-02-01

325

Passive dynamic walking of viscoelastic-legged rimless wheel  

Microsoft Academic Search

Limit cycle walking including passive-dynamic walkers is mathematically modeled as a nonlinear hybrid dynamical system with state jumps in general. The generated motion is natural and energy efficient, but it is still pointed out that there are many differences between limit cycle walking and human walking. Non-existence of the period of double-limb support in the former comes from the assumption

Fumihiko Asano; Junji Kawamoto

2012-01-01

326

Reactive navigation of an intelligent robotic walking aid  

Microsoft Academic Search

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

Birgit Graf

2001-01-01

327

Tempo and walking speed with music in the urban context  

PubMed Central

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

Fran?k, Marek; van Noorden, Leon; Režný, Lukáš

2014-01-01

328

18.366 Random Walks and Diffusion, Spring 2003  

E-print Network

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

Bazant, Martin Z.

329

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

330

18.366 Random Walks and Diffusion, Spring 2005  

E-print Network

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

Bazant, Martin Z.

331

Quantum Walks on Trees with Disorder: Decay, Diffusion, and Localization  

E-print Network

Quantum walks have been shown to have impressive transport properties compared to classical random walks. However, imperfections in the quantum walk algorithm can destroy any quantum mechanical speed-up due to Anderson localization. We numerically study the effect of static disorder on a quantum walk on the glued trees graph. For small disorder, we find that the dominant effect is a type of quantum decay, and not quantum localization. For intermediate disorder, there is a crossover to diffusive transport, while a localization transition is observed at large disorder, in agreement with Anderson localization on the Cayley tree.

Steven R. Jackson; Teng Jian Khoo; Frederick W. Strauch

2012-06-14

332

Implementing Quantum Walks Using Orbital Angular Momentum of Classical Light  

E-print Network

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.

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

2013-07-07

333

Robust and efficient walking with spring-like legs.  

PubMed

The development of bipedal walking robots is inspired by human walking. A way of implementing walking could be performed by mimicking human leg dynamics. A fundamental model, representing human leg dynamics during walking and running, is the bipedal spring-mass model which is the basis for this paper. The aim of this study is the identification of leg parameters leading to a compromise between robustness and energy efficiency in walking. It is found that, compared to asymmetric walking, symmetric walking with flatter angles of attack reveals such a compromise. With increasing leg stiffness, energy efficiency increases continuously. However, robustness is the maximum at moderate leg stiffness and decreases slightly with increasing stiffness. Hence, an adjustable leg compliance would be preferred, which is adaptable to the environment. If the ground is even, a high leg stiffness leads to energy efficient walking. However, if external perturbations are expected, e.g. when the robot walks on uneven terrain, the leg should be softer and the angle of attack flatter. In the case of underactuated robots with constant physical springs, the leg stiffness should be larger than k = 14 in order to use the most robust gait. Soft legs, however, lack in both robustness and efficiency. PMID:21079285

Rummel, J; Blum, Y; Seyfarth, A

2010-12-01

334

Generating random walks and polygons with stiffness in confinement  

NASA Astrophysics Data System (ADS)

The purpose of this paper is to explore ways to generate random walks and polygons in confinement with a bias toward stiffness. Here the stiffness refers to the curvature angle between two consecutive edges along the random walk or polygon. The stiffer the walk (polygon), the smaller this angle on average. Thus random walks and polygons with an elevated stiffness have lower than expected curvatures. The authors introduced and studied several generation algorithms with a stiffness parameter s\\gt 0 that regulates the expected curvature angle at a given vertex in which the random walks and polygons are generated one edge at a time using conditional probability density functions. Our generating algorithms also allow the generation of unconfined random walks and polygons with any desired mean curvature angle. In the case of random walks and polygons confined in a sphere of fixed radius, we observe that, as expected, stiff random walks or polygons are more likely to be close to the confinement boundary. The methods developed here require that the random walks and random polygons be rooted at the center of the confinement sphere.

Diao, Y.; Ernst, C.; Saarinen, S.; Ziegler, U.

2015-03-01

335

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

336

78 FR 25478 - Agency Information Collection Activities; Submission for OMB Review; Comment Request; Walking...  

Federal Register 2010, 2011, 2012, 2013, 2014

...OMB Review; Comment Request; Walking-Working Surfaces Standard ACTION: Notice...request (ICR) titled, ``Walking-Working Surfaces Standard,'' to the Office...collection requirements in the Walking-Working Surfaces Standard protect workers by...

2013-05-01

337

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

2009-07-01

338

Simulation of semi-passive dynamic walking for biped walking robot  

Microsoft Academic Search

The bipedal humanoid robot WABIAN-2R is developed to simulate human locomotion. Performing a walking motion requires a high torque at the ankle joint. WABIAN-2R consists of harmonic gears in its driveline system which increases the weight of each leg and respectively decreases the energy economy. Therefore, a new idea is proposed and developed in this paper through computer simulation to

A. M. M. Omer; R. Ghorbani; Hun-ok Lim; A. Takanishi

2009-01-01

339

When to walk away from a deal.  

PubMed

Deal making is glamorous; due diligence is not. That simple statement goes a long way toward explaining why so many companies have made so many acquisitions that have produced so little value. The momentum of a transaction is hard to resist once senior management has the target in its sights. Companies contract "deal fever," and due diligence all too often becomes an exercise in verifying the target's financial statements rather than conducting a fair analysis of the deal's strategic logic and the acquirer's ability to realize value from it. Seldom does the process lead managers to kill potential acquisitions, even when the deals are deeply flawed. In a recent Bain & Company survey of 250 international executives with M&A responsibilities, only 30% of them were satisfied with the rigor of their due diligence. And fully a third admitted they hadn't walked away from deals they had nagging doubts about. In this article, the authors, all Bain consultants, emphasize the importance of comprehensive due diligence practices and suggest ways companies can improve their capabilities in this area. They provide rich real-world examples of companies that have had varying levels of success with their due diligence processes, including Safeway, Odeon, American Sea-foods, and Kellogg's. Effective due diligence requires answering four basic questions: What are we really buying? What is the target's stand-alone value? Where are the synergies--and the skeletons? And what's our walk-away price? Each of these questions will prompt an even deeper level of querying that puts the broader, strategic rationale for acquisitions under a microscope. Successful acquirers pay close heed to the results of such in-depth investigations and analyses--to the extent that they are prepared to walk away from a deal, even in the very late stages of negotiations. PMID:15077370

Cullinan, Geoffrey; Le Roux, Jean-Marc; Weddigen, Rolf-Magnus

2004-04-01

340

Novel Image Encryption based on Quantum Walks  

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

341

Staircase polygons and recurrent lattice walks  

NASA Astrophysics Data System (ADS)

In this paper we derive a direct relationship between the staircase-polygon-generating function Zd of Guttmann and Prellberg [Phys. Rev. E 47, R2233 (1993)] and the generating function for recurrent lattice walks Pd for the simple (hyper-) cubic lattice in all dimensions d. A recursion formula is obtained for the Zd with respect to dimension, which leads to a simplified derivation of Guttmann and Prellberg's result for d=3, avoiding the use of the Heun function, and a derivation of their formula for d=4 from an integral representation is given in the Appendix.

Glasser, M. L.; Montaldi, E.

1993-10-01

342

Biased random walks and propagation failure.  

PubMed

The critical value of the reaction rate able to sustain the propagation of an invasive front is obtained for general non-Markovian biased random walks with reactions. From the Hamilton-Jacobi equation corresponding to the mean field equation we find that the critical reaction rate depends only on the mean waiting time and on the statistical properties of the jump length probability distribution function and is always underestimated by the diffusion approximation. If the reaction rate is larger than the jump frequency, invasion always succeeds, even in the case of maximal bias. Numerical simulations support our analytical predictions. PMID:17358121

Méndez, Vicenç; Fedotov, Sergei; Campos, Daniel; Horsthemke, Werner

2007-01-01

343

Propagation of quantum walks in electric fields.  

PubMed

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. PMID:24182244

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

2013-10-18

344

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

345

Random Walk on Random Infinite Looptrees  

NASA Astrophysics Data System (ADS)

Looptrees have recently arisen in the study of critical percolation on the uniform infinite planar triangulation. Here we consider random infinite looptrees defined as the local limit of the looptree associated with a critical Galton-Watson tree conditioned to be large. We study simple random walk on these infinite looptrees by means of providing estimates on volume and resistance growth. We prove that if the offspring distribution of the Galton-Watson process is in the domain of attraction of a stable distribution with index then the spectral dimension of the looptree is.

Björnberg, Jakob E.; Stefánsson, Sigurdur Örn

2015-03-01

346

A Light Dilaton in Walking Gauge Theories  

E-print Network

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.

Thomas Appelquist; Yang Bai

2010-12-24

347

Novel image encryption based on quantum walks.  

PubMed

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

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

2015-01-01

348

Novel Image Encryption based on Quantum Walks  

PubMed Central

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

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

2015-01-01

349

Access Excellence: A Walk Through the Gut  

NSDL National Science Digital Library

Hosted by the Access Excellence at the National Health Museum, this website features A Walk Through the Gut, a lesson created for high school students by educator VivianLee Ward. This hands-on lesson promotes cooperative learning by directing students to work together as they simulate and analyze the passage of food through the digestive system. Ms. Ward designed this one-hour life sciences lesson for special education and special needs students as well. The site includes short sections on Materials, Procedure / Description of Lesson, Group Questions, and more.

Ward, Vivian Lee

2007-12-12

350

On serious violence during sleep-walking.  

PubMed

It is not sufficiently realised that sleep-walking is not an hysterical condition, nor in any way related to epilepsy, nor that it can be accompanied by violent injury to the self or others. Three case reports here include that of a 14-year-old boy who rose from his bed at 2 a.m. and severely stabbed his five-year-old girl cousin. The sleeping mind is not in touch with reality and amnesia for events during sleep is usual. PMID:3830330

Oswald, I; Evans, J

1985-12-01

351

Quantum-walk-based search and centrality  

SciTech Connect

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

Berry, Scott D.; Wang, Jingbo B. [School of Physics, The University of Western Australia, Perth, WA 6009 (Australia)

2010-10-15

352

Thermodynamical asymmetries in whirling, jumping and walking  

NASA Astrophysics Data System (ADS)

We analyze, from the thermodynamical point of view, mechanical systems in which there is the production of mechanical energy due to an internal source of energy, and compare that analysis with a similar one for the ‘symmetric’ motion that occurs with energy dissipation. The analysis of the energetic asymmetries is instructive to put in evidence the role of thermodynamics even in the discussion of mechanical aspects. We illustrate the discussion with the well-known example of a person on a rotating platform outstretching and contracting his or her arms, and also with other common situations such as jumping and walking.

Güémez, J.; Fiolhais, M.

2014-05-01

353

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

PubMed

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

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

2014-08-01

354

Humanoid Robot Walking Control on Inclined Planes Utku Seven1  

E-print Network

is a difficult control problem. Walking just on even floor is not satisfactory for the applicability as the inputs to the fuzzy logic system. A foot pitch orientation compensator implemented independently to climb slopes of 8.5 degrees (15 percent grade). Keywords-- Humanoid robots, bipedal walk, inclined plane

Yanikoglu, Berrin

355

Stabilization of Lateral Motion in Passive Dynamic Walking  

Microsoft Academic Search

Passive dynamic walking refers to a class of bipedal machines that are able to walk down a gentle slope with no external control or en- ergy input. The legs swing naturally as pendula, and conservation of angular momentum governs the contact of the swing foot with the ground. Previous machines have been limited to planar motions. We extend the planar

Arthur D. Kuo

1999-01-01

356

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

2009-06-01

357

Stability Analysis of Passive Dynamic Walking of Quadrupeds  

Microsoft Academic Search

We introduce a detailed numerical simulation and analysis framework to extend the principles of passive dynamic walking to quadrupedal locomotion. Non-linear limit cycle methods are used to identify possible gaits and to analyze the stability and efficiency of quadrupedal passive dynamic walking. In doing so, special attention is paid to issues that are inherent to quadrupedal locomotion, such as the

C. David Remy; Keith W. Buffinton; Roland Siegwart

2010-01-01

358

Hierarchical implicit feedback structure in passive dynamic walking  

Microsoft Academic Search

The purpose of this paper is to analyze the stability of Passive Dynamic Walking (PDW) using a linearized analytical Poincare map. In particular, in this paper, we focus on a bifurcation phenomenon in PDW. Although the bifurcation of the walking period is one of the well-known features of PDW, it have not been studied sufficiently so far. Using techniques similar

Yasuhiro Sugimoto; Koichi Osuka

2007-01-01

359

Underactuated virtual passive dynamic walking with an upper body  

Microsoft Academic Search

Achieving energy-efficient dynamic walking has become one of the main subjects of research on robotic bipedal locomotion. Approaches based on passive-dynamic walkers can accomplish bipedal locomotion. However, passive dynamic walking has only been studied with the legs, and the effect of an upper body has not been clarified. This paper investigates the effect of an upper body on the efficiency

Fumihiko Asano; Zhi-Wei Luo

2008-01-01

360

Distracted walking: Cell phones increase injury risk for college pedestrians  

Microsoft Academic Search

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

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

2011-01-01

361

Energetics of Actively Powered Locomotion Using the Simplest Walking Model  

Microsoft Academic Search

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

Arthur D. Kuo

2002-01-01

362

Interactive rotoscoping through scale-space random walks  

Microsoft Academic Search

We present a novel rotoscoping method that provides accurate object boundaries while still remaining simple to use. We have designed this method so that a user familiar with existing, spline-based rotoscoping techniques will not need to significantly modify their workflow. Our method utilizes a modified version of the random walks segmentation algorithm, known as scale-space random walks (SSRW), to provide

Richard Rzeszutek; Thomas F. El-Maraghi; Dimitrios Androutsos

2009-01-01

363

The effect of walking speed on center of mass displacement  

Microsoft Academic Search

The movement of the center of mass (COM) during human walking has been hypothesized to follow a sinusoidal pattern in the vertical and mediolateral directions. The vertical COM displacement has been shown to increase with velocity, but little is known about the mediolateral movement of the COM. In our evaluation of the mediolateral COM displace- ment at several walking speeds,

Michael S. Orendurff; Ava D. Segal; Glenn K. Klute; Jocelyn S. Berge; Eric S. Rohr; Nancy J. Kadel

2004-01-01

364

Effect of Backward Walking on Attention: Possible Application on ADHD  

PubMed Central

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

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

2015-01-01

365

Trunk muscle activation patterns during walking at different speeds  

Microsoft Academic Search

Investigations of trunk muscle activation during gait are rare in the literature. As yet, the small body of literature on trunk muscle activation during gait does not include any systematic study on the influence of walking speed. Therefore, the aim of this study was to analyze trunk muscle activation patterns at different walking speeds. Fifteen healthy men were investigated during

Christoph Anders; Heiko Wagner; Christian Puta; Roland Grassme; Alexander Petrovitch; Hans-Christoph Scholle

2007-01-01

366

Critical RWRE on trees and tree-indexed random walks  

Microsoft Academic Search

We study the behavior of Random Walk in Random Environment (RWRE) on trees in the critical case left open in previous work. Representing the random walk by an electrical network, we assume that the ratios of resistances of neighboring edges of a tree Gamma are i.i.d.random variables whose logarithms have mean zero and finite variance. Then the resulting RWRE is

Robin Pemantle; Yuval Peres

2004-01-01

367

Promoting Discussion in the Science Classroom Using Gallery Walks  

ERIC Educational Resources Information Center

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

Francek, Mark

2006-01-01

368

Promoting Discussion in the Science Classroom Using Gallery Walks  

NSDL National Science Digital Library

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

Mark Francek

2006-09-01

369

ACTION DE DEUX INSECTICIDES SUR MELITTOBIA ACASTA WALK.  

E-print Network

.A.P.F., I.N.R.A., 86600 Lusignan SUMMARY EFFECTS OF 2 INSECTICIDES ON MEUTTOB1A A CASTA WALK AND ITS HOSTACTION DE DEUX INSECTICIDES SUR MELITTOBIA ACASTA WALK. ET SON HOTE : MEGACHILE PACIFICA PZ to the soaking of cells in insecticide solutions. This efficiency is reached above the concentration levels : 4

Boyer, Edmond

370

Nonlinear Pitch and Roll Estimation for Walking Robots  

Microsoft Academic Search

We study a nonlinear pitch and roll estimation problem for a 4-rigid body, aiming at a walking robot application. The approach taken is that sensor data from rate gyros and inclinometers are combined using a high-gain observer that can be proven to be exponentially convergent. The algorithm has successfully been evaluated experimentally during conditions resembling walking robot motion and has

Henrik Rehbinder; Xiaoming Hu

2000-01-01

371

Gait planning for energy efficiency in walking machines  

Microsoft Academic Search

This paper addresses the problem of achieving energy efficiency in statically stable walking machines without mechanically constraining the system. In contrast to previous work, power is minimized over an entire locomotion cycle, through optimal selection of walking parameters, rather than for a fixed instant of time only. Dynamic simulation experiments of a hexapod with full three degree-of-freedom legs are used

Duane W. Marhefka; David E. Orin

1997-01-01

372

PATH OPTIMIZATION FOR HUMANOID WALK PLANNING: AN EFFICIENT APPROACH  

E-print Network

PATH OPTIMIZATION FOR HUMANOID WALK PLANNING: AN EFFICIENT APPROACH Antonio El Khoury1,2 , Michel planning in cluttered environments. It presents a heuristic and efficient optimization method that takes, France aelkhour@laas.fr, taix@laas.fr, florent@laas.fr Keywords: humanoid robot, motion planning, walk

Paris-Sud XI, Université de

373

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

374

Infant Language Development Is Related to the Acquisition of Walking  

ERIC Educational Resources Information Center

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

Walle, Eric A.; Campos, Joseph J.

2014-01-01

375

When the beautiful game becomes a walk in the park.  

PubMed

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

2015-03-01

376

Well Planned Spontaneity: Some Tips for Conducting Guided Walks.  

ERIC Educational Resources Information Center

Provides guidelines for planning and conducting a guided nature walk of short duration (1-3 hours) that provides opportunities for spontaneous teachable moments. Includes pre-hike planning related to public relations, the theme of the walk, and the trail; and tips for matching the presentation of material, discussion, and group activities to…

Tucker, Brad

2001-01-01

377

Learning from Labeled and Unlabeled Data Using Random Walks  

E-print Network

walks and spectral graph theory, which shed light on the key steps in this algorithm. Keywords: semi-supervised learning, random walks, regularization, spectral graph theory. 1. Introduction We consider the general supervised learning methods is the Support Vector Machine (SVM) (Cortes and Vapnik, 1995; Vapnik, 1998

378

Learning from Labeled and Unlabeled Data Using Random Walks  

E-print Network

methods. Here we further investigate the algorithm using random walks and spectral graph theory, which learning methods is the Support Vector Machine (SVM) [9]. The problem of interest here is if we can]. Here we further investigate the algorithm using random walks and spectral graph theory, which shed

379

Random walk on the infinite cluster of the percolation model  

Microsoft Academic Search

Summary We consider random walk on the infinite cluster of bond percolation on Zd. We show that, in the supercritical regime whend?3, this random walk is a.s. transient. This conclusion is achieved by considering the infinite percolation cluster as a random electrical network in which each open edge has unit resistance. It is proved that the effective resistance of this

G. R. Grimmett; H. Kesten; Y. Zhang

1993-01-01

380

Trends in Biking and Walking Jessica Schoner & Greg Lindsey  

E-print Network

.0% City of St. Paul: 1.7% Rest of Ramsey County: 2.4% Weighted, Year-round #12;Walk Mode Share 2010 of Ramsey County: 4.2% Weighted, Year-round #12;Big Increase in Biking Between Minneapolis & St. Paul Within;"Primary Mode" Defined Hierarchically 1. School Bus 2. Transit 3. Auto 4. Bike 5. Walk 6. Other Trip diary

Minnesota, University of

381

Recycling Energy to Restore Impaired Ankle Function during Human Walking  

E-print Network

Recycling Energy to Restore Impaired Ankle Function during Human Walking Steven H. Collins1 that captures some of the energy that is normally dissipated by the leg and ``recycles'' it as positive ankle walking. Energy recycling restored ankle push-off to normal and reduced the net metabolic energy penalty

Collins, Steven H.

382

The 1991-1992 walking robot design  

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

383

Too far to walk or bike?  

PubMed

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

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

2013-01-01

384

Models of Walking Technicolor on the Lattice  

E-print Network

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

D. K. Sinclair; J. B. Kogut

2014-10-30

385

Continuous-Time Quantum Walks and Trapping  

E-print Network

Recent findings suggest that processes such as the electronic energy transfer through the photosynthetic antenna display quantal features, aspects known from the dynamics of charge carriers along polymer backbones. Hence, in modeling energy transfer one has to leave the classical, master-equation-type formalism and advance towards an increasingly quantum-mechanical picture, while still retaining a local description of the complex network of molecules involved in the transport, say through a tight-binding approach. Interestingly, the continuous time random walk (CTRW) picture, widely employed in describing transport in random environments, can be mathematically reformulated to yield a quantum-mechanical Hamiltonian of tight-binding type; the procedure uses the mathematical analogies between time-evolution operators in statistical and in quantum mechanics: The result are continuous-time quantum walks (CTQWs). However, beyond these formal analogies, CTRWs and CTQWs display vastly different physical properties. In particular, here we focus on trapping processes on a ring and show, both analytically and numerically, that distinct configurations of traps (ranging from periodical to random) yield strongly different behaviours for the quantal mean survival probability, while classically (under ordered conditions) we always find an exponential decay at long times.

Elena Agliari; Oliver Muelken; Alexander Blumen

2009-03-19

386

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

387

Improving the accuracy of walking piezo motors  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

388

Promoting walking among older adults living in retirement communities.  

PubMed

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

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

2012-07-01

389

Ballistic Phase of Self-Interacting Random Walks  

E-print Network

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

Dmitry Ioffe; Yvan Velenik

2008-04-03

390

Checklist and Pollard Walk butterfly survey methods on public lands  

USGS Publications Warehouse

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

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

1998-01-01

391

Self-paced versus fixed speed treadmill walking.  

PubMed

Instrumented treadmills are increasingly used in gait research, although the imposed walking speed is suggested to affect gait performance. A feedback-controlled treadmill that allows subjects to walk at their preferred speed, i.e. functioning in a self-paced (SP) mode, might be an attractive alternative, but could disturb gait through accelerations of the belt. We compared SP with fixed speed (FS) treadmill walking, and also considered various feedback modes. Nineteen healthy subjects walked on a dual-belt instrumented treadmill. Spatio-temporal, kinematic and kinetic gait parameters were derived from both the average stride patterns and stride-to-stride variability. For 15 out of 70 parameters significant differences were found between SP and FS. These differences were smaller than 1cm, 1°, 0.2 Nm and 0.2 W/kg for respectively stride length and width, joint kinematics, moments and powers. Since this is well within the normal stride variability, these differences were not considered to be clinically relevant, indicating that SP walking is not notably affected by belt accelerations. The long-term components of walking speed variability increased during SP walking (43%, p<0.01), suggesting that SP allows for more natural stride variability. Differences between SP feedback modes were predominantly found in the timescales of walking speed variability, while the gait pattern was similar between modes. Overall, the lack of clinically significant differences in gait pattern suggests that SP walking is a suitable alternative to fixed speed treadmill walking in gait analysis. PMID:24055003

Sloot, L H; van der Krogt, M M; Harlaar, J

2014-01-01

392

A Guided Walking Trail to Explore the Martin Luther King Jr. National Voting Rights Walk and Selma Antebellum Historic District  

Microsoft Academic Search

Historical documents, original and archival photos, and MS Publisher software were used to develop and promote a two mile guided walking trail incorporating the Martin Luther King, Jr. National Voting Rights Walk, Selma Antebellum Historic District and Bloch Park. The aim is to promote learning about Alabama history while enhancing fitness, as a planned activity of a programme to prevent

Brian F. Geiger; Karen A. Werner

2009-01-01

393

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

394

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

E-print Network

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

Harman, Neal.A.

395

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

PubMed Central

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

2013-01-01

396

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

E-print Network

are the main contributing factors in car crashes that involve pedestrian [11]. In most cases, drivers of the WalkSafe App that is capable of real-time detection of the front and back views of cars, indicating cars are approaching or moving away from the user, respectively. WalkSafe is implemented on Android

Torresani, Lorenzo

397

Pelvic motion measurement during over ground walking, analysis and implementation on the WalkTrainer reeducation device  

Microsoft Academic Search

Pelvic motions are of great importance while walking, and have thus to be taken into account when developing and controlling rehabilitation devices. This paper will first introduce a new reeducation device for paraplegic people: the WalkTrainer. This device is composed of a leg and pelvic orthosis, an active bodyweight support and closed loop muscle stimulation. Second, the six degrees of

Yves Stauffer; Yves Allemand; Mohamed Bouri; Jacques Fournier; Reymond Clavel; Patrick Metrailler; Roland Brodard; Fabienne Reynard

2008-01-01

398

Pilot investigation of the oxygen demands and metabolic cost of incremental shuttle walking and treadmill walking in patients with cardiovascular disease  

PubMed Central

Objective To determine if the metabolic cost of the incremental shuttle-walking test protocol is the same as treadmill walking or predicted values of walking-speed equations. Setting Primary care (community-based cardiac rehabilitation). Participants Eight Caucasian cardiac rehabilitation patients (7 males) with a mean age of 67±5.2?years. Primary and secondary outcome measures Oxygen consumption, metabolic power and energy cost of walking during treadmill and shuttle walking performed in a balanced order with 1?week between trials. Results Average overall energy cost per metre was higher during treadmill walking (3.22±0.55?J?kg/m) than during shuttle walking (3.00±0.41?J?kg/m). There were significant post hoc effects at 0.67?m/s (p<0.004) and 0.84?m/s (p<0.001), where the energy cost of treadmill walking was significantly higher than that of shuttle walking. This pattern was reversed at walking speeds 1.52?m/s (p<0.042) and 1.69?m/s (p<0.007) where shuttle walking had a greater energy cost per metre than treadmill walking. At all walking speeds, the energy cost of shuttle walking was higher than that predicted using the American College of Sports Medicine walking equations. Conclusions The energetic demands of shuttle walking were fundamentally different from those of treadmill walking and should not be directly compared. We warn against estimating the metabolic cost of the incremental shuttle-walking test using the current walking-speed equations. PMID:25227624

Almodhy, M; Beneke, R; Cardoso, F; Taylor, M J D; Sandercock, G R H

2014-01-01

399

Analysis of human abnormal walking using a multi-body model: joint models for abnormal walking and walking aids to reduce compensatory action.  

PubMed

This paper proposes new models of diseased joints and evaluates the effectiveness of walking aids such as a cane and a brace for compensating for lost functions due to joint disorders. The ZMJ concept described in the previous work (Yamashita and Tagawa, 1988. In: Radharaman (Ed.), Robotics and Factories of the Future'87. Springer, New York, pp. 670-677) is modified into three joint models as follows: a passive element joint (PEJ) which has a spring at the diseased joint; a constrained range joint (CRJ), the motion of which stays within some constrained relative angle; a partial moment joint (PMJ) which can produce a partial amount of the moment produced about the joint in normal walking. A cane can enlarge a supporting area and adjust the posture of the upper torso to be upright. An ischial weight-bearing brace is effective for conservative management of hip disorders by reducing a load to the joint (Shiba et al., 1998. Clinical Orthopaedics and Related Research 351, 149-157). Walking aids like a cane or brace have been conveniently used by the handicapped. Abnormal walking was simulated for each joint model. Dynamic effects of a cane and a brace on abnormal walking were examined by the multi-body walking model. PMID:10940399

Tagawa, Y; Shiba, N; Matsuo, S; Yamashita, T

2000-11-01

400

Using built environment characteristics to predict walking for exercise  

PubMed Central

Background Environments conducive to walking may help people avoid sedentary lifestyles and associated diseases. Recent studies developed walkability models combining several built environment characteristics to optimally predict walking. Developing and testing such models with the same data could lead to overestimating one's ability to predict walking in an independent sample of the population. More accurate estimates of model fit can be obtained by splitting a single study population into training and validation sets (holdout approach) or through developing and evaluating models in different populations. We used these two approaches to test whether built environment characteristics near the home predict walking for exercise. Study participants lived in western Washington State and were adult members of a health maintenance organization. The physical activity data used in this study were collected by telephone interview and were selected for their relevance to cardiovascular disease. In order to limit confounding by prior health conditions, the sample was restricted to participants in good self-reported health and without a documented history of cardiovascular disease. Results For 1,608 participants meeting the inclusion criteria, the mean age was 64 years, 90 percent were white, 37 percent had a college degree, and 62 percent of participants reported that they walked for exercise. Single built environment characteristics, such as residential density or connectivity, did not significantly predict walking for exercise. Regression models using multiple built environment characteristics to predict walking were not successful at predicting walking for exercise in an independent population sample. In the validation set, none of the logistic models had a C-statistic confidence interval excluding the null value of 0.5, and none of the linear models explained more than one percent of the variance in time spent walking for exercise. We did not detect significant differences in walking for exercise among census areas or postal codes, which were used as proxies for neighborhoods. Conclusion None of the built environment characteristics significantly predicted walking for exercise, nor did combinations of these characteristics predict walking for exercise when tested using a holdout approach. These results reflect a lack of neighborhood-level variation in walking for exercise for the population studied. PMID:18312660

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

2008-01-01

401

Walking training associated with virtual reality-based training increases walking speed of individuals with chronic stroke: systematic review with meta-analysis  

PubMed Central

OBJECTIVE: To systematically review the available evidence on the efficacy of walking training associated with virtual reality-based training in patients with stroke. The specific questions were: Is walking training associated with virtual reality-based training effective in increasing walking speed after stroke? Is this type of intervention more effective in increasing walking speed, than non-virtual reality-based walking interventions? METHOD: A systematic review with meta-analysis of randomized clinical trials was conducted. Participants were adults with chronic stroke and the experimental intervention was walking training associated with virtual reality-based training to increase walking speed. The outcome data regarding walking speed were extracted from the eligible trials and were combined using a meta-analysis approach. RESULTS: Seven trials representing eight comparisons were included in this systematic review. Overall, the virtual reality-based training increased walking speed by 0.17 m/s (IC 95% 0.08 to 0.26), compared with placebo/nothing or non-walking interventions. In addition, the virtual reality-based training increased walking speed by 0.15 m/s (IC 95% 0.05 to 0.24), compared with non-virtual reality walking interventions. CONCLUSIONS: This review provided evidence that walking training associated with virtual reality-based training was effective in increasing walking speed after stroke, and resulted in better results than non-virtual reality interventions. PMID:25590442

Rodrigues-Baroni, Juliana M.; Nascimento, Lucas R.; Ada, Louise; Teixeira-Salmela, Luci F.

2014-01-01

402

[Walking mechanism embedded in body structure].  

PubMed

In this note, we consider the control system of a biological system. Further, we point out the existence of the problem of indivisibility in the control system. To understand the principle of mobile adaptability embedded in the control system, we must solve the problem of indivisibility. To solve this problem, we propose the concept of an implicit control law. In addition to this proposal, we consider the usual explicit control law. Next, we demonstrate an example of the implicit control law embedded in the problem of a passive dynamic walking system. Finally, we state that the intelligence of the biological system must be constructed using both the explicit and the implicit control laws. PMID:21068453

Osuka, Koichi

2010-11-01

403

Exploring Toe Walking in a Bipedal Robot  

NASA Astrophysics Data System (ADS)

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

Smith, James Andrew; Seyfarth, Andre

404

Lazy random walks for superpixel segmentation.  

PubMed

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

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

2014-04-01

405

Walking speed: the functional vital sign.  

PubMed

Walking speed (WS) is a valid, reliable, and sensitive measure appropriate for assessing and monitoring functional status and overall health in a wide range of populations. These capabilities have led to its designation as the "sixth vital sign". By synthesizing the available evidence on WS, this scholarly review article provides clinicians with a reference tool regarding this robust measure. Recommendations on testing procedures for assessing WS, including optimal distance, inclusion of acceleration and deceleration phases, instructions, and instrumentation are given. After assessing an individual's WS, clinicians need to know what this value represents. Therefore, WS cut-off values and the corresponding predicted outcomes, as well as minimal detectable change values for specific populations and settings are provided. PMID:24812254

Middleton, Addie; Fritz, Stacy L; Lusardi, Michelle

2015-04-01

406

Random walks in directed modular networks  

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

407

Random time averaged diffusivities for Lévy walks  

NASA Astrophysics Data System (ADS)

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

Froemberg, D.; Barkai, E.

2013-07-01

408

Random Walks on Free Periodic Groups  

NASA Astrophysics Data System (ADS)

An upper estimate is obtained for the growth exponent of the set of all uncancellable words equal to 1 in a group given by a system of defining relations with the Dehn condition. By a theorem of Grigorchuk, this yields a sufficient test for the transience of a random walk on a group given by a system of defining relations with the Dehn condition, and for the nonamenability of such a group. It is proved that the free periodic groups B(m,n) with m>=2 and odd n>=665 satisfy this test. A question asked by Kesten in 1959 is thereby answered in the negative, and a conjecture put foth earlier by the author is confirmed. Bibliography: 7 titles.

Adyan, S. I.

1983-06-01

409

The QWalk simulator of quantum walks  

NASA Astrophysics Data System (ADS)

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

Marquezino, F. L.; Portugal, R.

2008-09-01

410

Assessment of a Solar System Walk  

NASA Astrophysics Data System (ADS)

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

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

2010-04-01

411

Course 8: Statistics of Knots and Entangled Random Walks  

NASA Astrophysics Data System (ADS)

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 non-commutative groups 3.1 Brownian bridges on simplest non-commutative groups and knot statistics 3.2 Random walks on locally free groups 3.3 Analytic results for random walks on locally free groups 3.4 Brownian bridges on Lobachevskii plane and products of non-commutative random matrices 4 Conformal methods in statistics of random walks with topological constraints 4.1 Construction of nonabelian connections for ?2 and PSL(2, Z ) from conformal methods 4.2 Random walk on double punctured plane and conformal field theory 4.3 Statistics of random walks with topological constraints in the two-dimensional lattices of obstacles 5 Physical applications. Polymer language in statistics of entangled chain-like objects 5.1 Polymer chain in 3D-array of obstacles 5.2 Collapsed phase of unknotted polymer 6 Some "tight" problems of the probability theory and statistical physics 6.1 Remarks and comments to Section 2 6.2 Remarks and comments to Sections 3 and 4 6.3 Remarks and comments to Section 5

Nechaev, S.

412

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

413

Ecological Validity of Walking Capacity Tests in Multiple Sclerosis  

PubMed Central

Background Ecological validity implicates in how far clinical assessments refer to real life. Short clinical gait tests up to ten meters and 2- or 6-Minutes Walking Tests (2MWT/6MWT) are used as performance-based outcomes in Multiple Sclerosis (MS) studies and considered as moderately associated with real life mobility. Objective To investigate the ecological validity of 10 Meter Walking Test (10mWT), 2MWT and 6MWT. Methods Persons with MS performed 10mWT, 6MWT including 2MWT and 7 recorded days by accelerometry. Ecological validity was assumed if walking tests represented a typical walking sequence in real-life and correlations with accelerometry parameters were strong. Results In this cohort (n=28, medians: age=45, EDSS=3.2, disease duration=9 years), uninterrupted walking of 2 or 6 minutes occurred not frequent in real life (2.61 and 0.35 sequences/day). 10mWT correlated only with slow walking speed quantiles in real life. 2MWT and 6MWT correlated moderately with most real life walking parameters. Conclusion Clinical gait tests over a few meters have a poor ecological validity while validity is moderate for 2MWT and 6MWT. Mobile accelerometry offers the opportunity to control and improve the ecological validity of MS mobility outcomes. PMID:25879750

Stellmann, J. P.; Neuhaus, A.; Götze, N.; Briken, S.; Lederer, C.; Schimpl, M.; Heesen, C.; Daumer, M.

2015-01-01

414

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. PMID:23477577

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

2013-01-01

415

Effects of galvanic vestibular stimulation during human walking.  

PubMed

1. To identify vestibular influences on human walking, galvanic vestibular stimulation was applied to normal adult subjects as they walked to a previously seen target. A transmastoidal step stimulus commenced as subjects started walking. With the eyes shut, the galvanic stimulus caused large turns towards the side with the anodal current. 2. Ability to perceive the trajectory of gait without visual cues was measured by guiding blindfolded subjects from one arbitrary point to another, either walking or seated in a wheelchair. On reaching a destination position and removing the blindfold, subjects pointed to indicate the starting position. Subjects made considerable errors in estimating the trajectory, but were equally accurate whether in the wheelchair or walking. 3. To determine the effects of vestibular stimulation on the perception of trajectory, the galvanic stimulus was applied to blindfolded subjects as they were guided from one point to another in the wheelchair. The vestibular stimulus produced an illusory shift in the trajectory travelled. This shift was towards the side with the cathode, i.e. in the opposite direction to the turn produced by the stimulus during walking. 4. We conclude that galvanic vestibular stimulation during walking causes subjects to turn from their planned trajectory. In part, this altered course may compensate for an altered perception of trajectory produced by the stimulus. However, altered perception of the vertical or the base of support, or direct vestibulo-fugal influences on the leg muscles could contribute to the changes in gait. PMID:10358131

Fitzpatrick, R C; Wardman, D L; Taylor, J L

1999-06-15

416

Energy exchange between subject and belt during treadmill walking.  

PubMed

Treadmill walking aims to simulate overground walking, but intra-stride belt speed variations of treadmills result in some interaction between treadmill and subject, possibly obstructing this aim. Especially in self-paced treadmill walking, in which the belt speed constantly adjusts to the subject, these interactions might affect the gait pattern significantly. The aim of this study was to quantify the energy exchange between subject and treadmill, during the fixed speed (FS) and self-paced (SP) modes of treadmill walking. Eighteen subjects walked on a dual-belt instrumented treadmill at both modes. The energy exchange was calculated as the integration of the product of the belt speed deviation and the fore-aft ground reaction force over the stride cycle. The total positive energy exchange was 0.44 J/stride and the negative exchange was 0.11 J/stride, which was both less than 1.6% of the performed work on the center of mass. Energy was mainly exchanged from subject to treadmill during both the braking and propulsive phase of gait. The two treadmill modes showed a similar pattern of energy exchange, with a slightly increased energy exchange during the braking phase of SP walking. It is concluded that treadmill walking is only mildly disturbed by subject-belt interactions when using instrumented treadmills with adequate belt control. PMID:24589022

Sloot, L H; van der Krogt, M M; Harlaar, J

2014-04-11

417

Spectral and asymptotic properties of Grover walks on crystal lattice  

E-print Network

We propose a twisted Szegedy walk for estimating the limit behavior of a discrete-time quantum walk on a crystal lattice, an infinite abelian covering graph, whose notion was introduced by [14]. First, we show that the spectrum of the twisted Szegedy walk on the quotient graph can be expressed by mapping the spectrum of a twisted random walk onto the unit circle. Secondly, we show that the spatial Fourier transform of the twisted Szegedy walk on a finite graph with appropriate parameters becomes the Grover walk on its infinite abelian covering graph. Finally, as an application, we show that if the Betti number of the quotient graph is strictly greater than one, then localization is ensured with some appropriated initial state. We also compute the limit density function for the Grover walk on $\\mathbb{Z}^d$ with flip flop shift, which implies the coexistence of linear spreading and localization. We partially obtain the abstractive shape of the limit density function: the support is within the $d$-dimensional sphere of radius $1/\\sqrt{d}$, and $2^d$ singular points reside on the sphere's surface.

Yusuke Higuchi; Norio Konno; Iwao Sato; Etsuo Segawa

2014-10-22

418

Side by side treadmill walking with intentionally desynchronized gait.  

PubMed

Humans demonstrate an innate desire to synchronize stepping when walking side by side. This behavior requires modification of each person's gait, which may increase for pairings with very different walking patterns. The purpose of this study was to compare locomotor behavior for conditions in which partners exhibited similar and substantially different walking patterns. Twenty-six unimpaired subjects walked on a motorized treadmill at their preferred walking speed for three trials: by themselves (SOLO), next to someone on an adjacent treadmill (PAIRED), and next to someone who purposely avoided synchronization by altering stride times and/or lengths (DeSYNC). Means, coefficients of variance, approximate entropy (ApEn), rate of autocorrelation decay (?), and estimates of maximal Lyapunov exponents (?*) were calculated for several dependent variables taken from sagittal plane kinematic data. Few differences in behavior were noted when the PAIRED condition was compared to the SOLO condition. However, the DeSYNC condition resulted in several alterations in ApEn, ?, and ?*. These results suggest that greater differences in walking pattern between partners will facilitate greater modification to an individual's gait. Additional study of side by side walking may hold implications for understanding the control of gait in humans and may have application in a clinical setting. PMID:23001358

Nessler, Jeff A; McMillan, David; Schoulten, Michael; Shallow, Teresa; Stewart, Brianna; De Leone, Charles

2013-08-01

419

Perfect State Transfer in Laplacian Quantum Walk  

E-print Network

For a graph $G$ and a related symmetric matrix $M$, the continuous-time quantum walk on $G$ relative to $M$ is defined as the unitary matrix $U(t) = \\exp(-itM)$, where $t$ varies over the reals. Perfect state transfer occurs between vertices $u$ and $v$ at time $\\tau$ if the $(u,v)$-entry of $U(\\tau)$ has unit magnitude. This paper studies quantum walks relative to graph Laplacians. Some main observations include the following closure properties for perfect state transfer: (1) If a $n$-vertex graph has perfect state transfer at time $\\tau$ relative to the Laplacian, then so does its complement if $n\\tau$ is an integer multiple of $2\\pi$. As a corollary, the double cone over any $m$-vertex graph has perfect state transfer relative to the Laplacian if and only if $m \\equiv 2 \\pmod{4}$. This was previously known for a double cone over a clique (S. Bose, A. Casaccino, S. Mancini, S. Severini, Int. J. Quant. Inf., 7:11, 2009). (2) If a graph $G$ has perfect state transfer at time $\\tau$ relative to the normalized Laplacian, then so does the weak product $G \\times H$ if for any normalized Laplacian eigenvalues $\\lambda$ of $G$ and $\\mu$ of $H$, we have $\\mu(\\lambda-1)\\tau$ is an integer multiple of $2\\pi$. As a corollary, a weak product of $P_{3}$ with an even clique or an odd cube has perfect state transfer relative to the normalized Laplacian. It was known earlier that a weak product of a circulant with odd integer eigenvalues and an even cube or a Cartesian power of $P_{3}$ has perfect state transfer relative to the adjacency matrix. As for negative results, no path with four vertices or more has antipodal perfect state transfer relative to the normalized Laplacian. This almost matches the state of affairs under the adjacency matrix (C. Godsil, Discrete Math., 312:1, 2011).

R. Alvir; S. Dever; B Lovitz; J. Myer; C. Tamon; Y. Xu; H. Zhan

2014-09-20

420

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

421

Some Results In Passive-Dynamic Walking Mariano Garcia Andy Ruina  

E-print Network

Some Results In Passive-Dynamic Walking Mariano Garcia Andy Ruina Michael Coleman Anindya about human and robot walking may be to learn about passive-dynamic walking. This Euromech conference 1997 [18]. #12;1.1 Passive-Dynamic Walking Models Pure passive-dynamic models are built (theoretically

Ruina, Andy L.

422

A unified formulation and solutions to gait generation problems based on passive dynamic walking  

Microsoft Academic Search

Principal mechanism of passive dynamic walking is studied from the mechanical energy point of view, and novel gait generation and control methods based on passive dynamic walking are proposed. Firstly, 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.

F. ASANO; Z. W. LUO

2003-01-01

423

Swing leg retraction helps biped walking stability M. Wisse*, C. G. Atkeson, D. K. Kloimwieder  

E-print Network

in passive dynamic walking models, in running models, and in robot juggling. For this study, we use a simple. The primary motivation to study swing leg retraction comes from our previous work on passive dynamic walking [15], [4], [18]. Passive dynamic walking [11] robots can demonstrate stable walking without any

Atkeson, Christopher G.

424

Stabilization of quasi-passive-dynamic-walking based on delayed feedback control  

Microsoft Academic Search

In this paper, we introduce a new control method of quasi-passive dynamic walking for a biped walking robot. The control low uses actuators just only to maintain the passive walking. First, focusing on the contact phase of swing leg, the stability analysis of passive walking robot is performed through a discrete-time system of the robot. Second, we propose a new

Koichi Osuka; Yasuhiro Sugimoto

2002-01-01

425

Dynamical model verification of passive dynamic walking with a compass model prototype  

Microsoft Academic Search

In this paper we try to investigate the dynamical models' adequacy of Passive dynamic walking robot. For this purpose, we developed a new prototype passive dynamic walking robot which has capabilities of capturing data, and then analyzed its walking behavior by walking experiments.

Masatsugu Iribe; Tetsuya Kinugasa; Yasuhiro Sugimoto; Koichi Osuka

2010-01-01

426

Simulating the Simplest Walking Model Using Altair Hyperworks 9.0  

E-print Network

.g. the Cornell Ranger, the kneed passive-walking bi-ped, and so on) have been inspired by passive-dynamic walking are involved in simulating passive-dynamic walking models: first the governing equations of motion are derived walking model (Garcia, et al - 1998) using Altair's Hyperworks 9.0, a dynamic simulation software. The aim

Ruina, Andy L.

427

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

E-print Network

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

Peterson, Jonathon

428

Combining Passive Haptics with Redirected Walking luv@cs.unc.edu  

E-print Network

Combining Passive Haptics with Redirected Walking Luv Kohli luv@cs.unc.edu Eric Burns burns effectively to provide a sense of touch to users (Insko, et al., 2001). Redirected walking is a promising the effectiveness of redirected walking [3]. With redirected walking, the virtual world is imperceptibly rotated

Whitton, Mary C.

429

VELOCITY-DEPENDENT DYNAMIC CURVATURE GAIN FOR REDIRECTED WALKING 1 Velocity-Dependent Dynamic Curvature Gain  

E-print Network

VELOCITY-DEPENDENT DYNAMIC CURVATURE GAIN FOR REDIRECTED WALKING 1 Velocity-Dependent Dynamic Curvature Gain for Redirected Walking Christian T. Neth, Jan L. Souman, David Engel, Uwe Kloos, Heinrich H. B¨ulthoff and Betty J. Mohler Abstract--Redirected walking techniques allow people to walk

430

ESTIMATION OF DETECTION THRESHOLDS FOR REDIRECTED WALKING TECHNIQUES 1 Estimation of Detection Thresholds for  

E-print Network

ESTIMATION OF DETECTION THRESHOLDS FOR REDIRECTED WALKING TECHNIQUES 1 Estimation of Detection Thresholds for Redirected Walking Techniques Frank Steinicke, Member, IEEE, Gerd Bruder, Student Member, IEEE they believe they are walking straight. Index Terms--Virtual reality, virtual locomotion, redirected walking

Hinrichs, Klaus

431

VELOCITY-DEPENDENT DYNAMIC CURVATURE GAIN FOR REDIRECTED WALKING 1 Velocity-Dependent Dynamic Curvature Gain  

E-print Network

VELOCITY-DEPENDENT DYNAMIC CURVATURE GAIN FOR REDIRECTED WALKING 1 Velocity-Dependent Dynamic Curvature Gain for Redirected Walking Christian T. Neth, Jan L. Souman, David Engel, Uwe Kloos, Heinrich H. B¨ulthoff and Betty J. Mohler Abstract--Redirected walking (RDW) techniques allow people to walk

432

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

433

Random Walks in Weyl Chambers and the Decomposition of Tensor Powers  

Microsoft Academic Search

We consider a class of random walks on a lattice, introduced by Gessel and Zeilberger, for which the reflection principle can be used to count the number of k-step walks between two points which stay within a chamber of a Weyl group. We prove three independent results about such “reflectable walks”: first, a classification of all such walks; second, many

David J. Grabiner; Peter Magyar

1993-01-01

434

Radio Frequency Identification Walking Stick (RFIWS): A device for the blind  

Microsoft Academic Search

The paper outlines the project undertaken in developing prototype of Radio Frequency Identification Walking Stick (RFIWS). The device intended to assist the blind during walking on a sidewalk. Many of the blind people used the traditional method like dog and old design of walking stick as their guide to walk on the sidewalk. The limitation of this method is the

Mohammad Farid Saaid; Ismarani Ismail; Mohd Zikrul Hakim Noor

2009-01-01

435

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

ERIC Educational Resources Information Center

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

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

2009-01-01

436

Walking after spinal cord injury. Goal or wish?  

PubMed

Less than a third of patients walk again after a spinal cord injury, whereas every one of them wants to try. Residual function, energy expenditure, the extent of orthotic support needed, and patient motivation will determine the outcome. Functional electrical stimulation and other new orthotic designs have not notably increased the number of persons able to walk after a spinal injury. Rehabilitation professionals can use patient education, illustrating relearning to walk with examples of infants' and toddlers' progress, to assist patients in understanding their abilities and limitations. The final decision on ambulation and orthotic prescriptions can be made in stages after a patient adjusts to a wheelchair-independent level. PMID:1866961

Subbarao, J V

1991-05-01

437

Quantum state revivals in quantum walks on cycles  

E-print Network

Recurrence in the classical random walk is well known and described by the P\\'olya number. For quantum walks, recurrence is similarly understood in terms of the probability of a localized quantum walker to return to its origin. Under certain circumstances the quantum walker may also return to an arbitrary initial quantum state in a finite number of steps. Quantum state revivals in quantum walks on circles using coin operators which are constant in time and uniform across the path have been described before but only incompletely. In this paper we find the general conditions for which full-quantum state revival will occur.

Phillip R. Dukes

2014-11-14

438

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

439

Numerical and Analytic Studies of Random-Walk Models.  

NASA Astrophysics Data System (ADS)

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, in order to test the conformal-invariance theory predictions. Our numerical results strongly support the theory. Our second numerical project aims to test the hyperscaling relation dnu = 2 Delta_4-gamma for self-avoiding walks in 2 and 3 dimensions. We apply the pivot method to generate pairs of self-avoiding walks, and then for each pair, using the Karp-Luby algorithm, perform an inner -loop Monte Carlo calculation of the number of different translates of one walk that makes at least one intersection with the other. Applying a least-squares fit to estimate the exponents, we have obtained strong numerical evidence that the hyperscaling relation is true in 3 dimensions. Our great amount of data for walks of unprecedented length(up to 80000 steps), yield a updated value for the end-to-end distance and radius of gyration exponent nu = 0.588 +/- 0.001 (95% confidence limit), which comes out in good agreement with the renormalization -group prediction. In an analytic study of random-walk models, we introduce multi-colored random-walk models and generalize the Symanzik and B.F.S. random-walk representations to the multi-colored case. We prove that the zero-component lambdavarphi^2psi^2 theory can be represented by a two-color mutually -repelling random-walk model, and it becomes the mutually -avoiding walk model in the limit lambda to infty. However, our main concern and major break-through lies in the study of the two-point correlation function for the lambda varphi^2psi^2 theory with N > 0 components. By representing it as a two-color random-walk expansion, we succeed in proving that the two-point correlation function decays exponentially even in absence of the bare mass term, which implies that the lambdavarphi^2psi ^2 theory at fixed lambda > 0 will never reach criticality.

Li, Bin

440

The RANLUX Generator:. Resonances in a Random Walk Test  

NASA Astrophysics Data System (ADS)

Using a recently proposed directed random walk test, we systematically investigate the popular random number generator RANLUX developed by Lüscher and implemented by James. We confirm the good quality of this generator with the recommended luxury level. At a smaller luxury level (for instance equal to 1) resonances are observed in the random walk test. We also find that the lagged Fibonacci and Subtract-with-Carry recipes exhibit similar failures in the random walk test. A revised analysis of the corresponding dynamical systems leads to the observation of resonances in the eigenvalues of Jacobi matrix.

Shchur, Lev N.; Butera, Paolo

441

Perception, planning, and control for walking on rugged terrain  

NASA Technical Reports Server (NTRS)

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

Simmons, Reid; Krotkov, Eric

1991-01-01

442

Walking, running, and resting under time, distance, and average speed constraints: optimality of walk–run–rest mixtures  

PubMed Central

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

Long, Leroy L.; Srinivasan, Manoj

2013-01-01

443

On the Relationship Between Continuous and Discrete-Time Quantum Walk  

Microsoft Academic Search

Quantum walk is one of the main tools for quantum algorithms. Defined by analogy to classical random walk, a quantum walk\\u000a is a time-homogeneous quantum process on a graph. Both random and quantum walks can be defined either in continuous or discrete\\u000a time. But whereas a continuous-time random walk can be obtained as the limit of a sequence of discrete-time

Andrew M. Childs

2010-01-01

444

The experimental study on the contact process of passive walking  

NASA Astrophysics Data System (ADS)

The passive dynamic walking is a new concept of biped walking. Researchers have been working on this area with both theoretical analysis and experimental analysis ever since McGeer. This paper presents our compass-like passive walking model with a new set of testing system. Two gyroscopes are used for measuring the angles of two legs, and ten FlexiForce sensors are used for measuring the contact forces on the feet. We got the experimental data on the passive walking process with the validated testing system. A great emphasis was put on the contact process between the feet and the slope. The contact process of the stance leg was divided into four sections, and differences between the real testing contact process and the classic analytical contact process with no bouncing and slipping were summarized.

Qi, Feng; Bi, Lai-Ye; Wang, Tian-Shu; Li, Jun-Feng

2012-08-01

445

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

NASA Technical Reports Server (NTRS)

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

1963-01-01

446

On time scale invariance of random walks in confined space.  

PubMed

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

Bearup, Daniel; Petrovskii, Sergei

2015-02-21

447

BCI Controlled Walking Simulator For a BCI Driven FES Device  

E-print Network

to spinal cord injury (SCI), a BCI controlled walking simulator was developed SAmulaAon; Spinal Cord Injury; Gait BACKGROUND Spinal cord injury (SCI) paAents are o and manipulate their environment by "thought," thereby bypassing a damaged spinal

Nenadic, Zoran

448

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

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

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

449

Developing Questions for Gallery Walk to Engage Higher Order Thinking  

NSDL National Science Digital Library

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

450

A scaling law for random walks on networks  

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

451

Base Station Walk-Back - Duration: 2:10.  

NASA Video Gallery

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

452

Human walking model predicts joint mechanics, electromyography and mechanical economy  

E-print Network

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

Endo, Ken

453

The hydrodynamics of water-walking insects and spiders  

E-print Network

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

Hu, David L., 1979-

2006-01-01

454

Tail Kinematics of Juvenile Common Snapping Turtles during Aquatic Walking  

E-print Network

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

Blob, Richard W.

455

Characterisation of walking loads by 3D inertial motion tracking  

NASA Astrophysics Data System (ADS)

The present contribution analyses the walking behaviour of pedestrians in situ by 3D inertial motion tracking. The technique is first tested in laboratory experiments with simultaneous registration of the ground reaction forces. The registered motion of the pedestrian allows for the identification of stride-to-stride variations, which is usually disregarded in the simulation of walking forces. Subsequently, motion tracking is used to register the walking behaviour of (groups of) pedestrians during in situ measurements on a footbridge. The calibrated numerical model of the structure and the information gathered using the motion tracking system enables detailed simulation of the step-by-step pedestrian induced vibrations. Accounting for the in situ identified walking variability of the test-subjects leads to a significantly improved agreement between the measured and the simulated structural response.

Van Nimmen, K.; Lombaert, G.; Jonkers, I.; De Roeck, G.; Van den Broeck, P.

2014-09-01

456

A scaling law for random walks on networks  

PubMed Central

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

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

2014-01-01

457

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

458

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

459

On the Mechanics of Functional Asymmetry in Bipedal Walking  

PubMed Central

This paper uses two symmetrical models, the passive compass-gait biped and a five-link 3D biped, to computationally investigate the cause and function of gait asymmetry. We show that for a range of slope angles during passive 2D walking and mass distributions during controlled 3D walking, these models have asymmetric walking patterns between the left and right legs due to the phenomenon of spontaneous symmetry-breaking. In both cases a stable asymmetric family of gaits emerges from a symmetric family of gaits as the total energy increases (e.g., fast speeds). The ground reaction forces of each leg reflect different roles, roughly corresponding to support, propulsion, and motion control as proposed by the hypothesis of functional asymmetry in able-bodied human walking. These results suggest that body mechanics, independent of neurophysiological mechanisms such as leg dominance, may contribute to able-bodied gait asymmetry. PMID:22328168

Dhaher, Yasin Y.; Degani, Amir; Lynch, Kevin M.

2014-01-01

460

Group velocity of discrete-time quantum walks  

SciTech Connect

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

2009-05-15

461

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.

Joe Dellinger

462

Online pose classification and walking speed estimation using handheld devices  

E-print Network

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

Park, Jun-geun

463

Robust execution of bipedal walking tasks from biomechanical principles  

E-print Network

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

Hofmann, Andreas G. (Andreas Gunther)

2006-01-01

464

Robust Execution of Bipedal Walking Tasks From Biomechanical Principles  

E-print Network

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

Hofmann, Andreas

2006-04-28

465

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 ...

466

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 ...

467

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 ...

468

Gallery Walk Questions about Time and Earth History  

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 time and earth history. The questions are organized according to the ...

469

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 ...

470

A scaling law for random walks on networks.  

PubMed

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

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

2014-01-01

471

Kinematic study of human ankle control during walking  

E-print Network

In order to determine the extent to which ankle motion is voluntarily controlled during walking, angular velocity measurements at the ankle were taken in two cases. In the first case, subjects were seated and instructed ...

Zimmerman, Julia C

2009-01-01

472

A Walk in the Woods: Or, What Is Art?  

ERIC Educational Resources Information Center

Presents a passage from Tolstoy's essay "The School at Yasnaya Polyana." Discusses his experience as a teacher walking through the woods with several children and telling them stories. Describes their reactions and personalities, all very different. (SC)

Tolstoy, Leo

1999-01-01

473

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

474

Sleep-walking a rarest side effect of zolpidem.  

PubMed

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

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

2015-01-01

475

Powered Ankle–Foot Prosthesis Improves Walking Metabolic Economy  

E-print Network

At moderate to fast walking speeds, the human ankle provides net positive work at high-mechanical-power output to propel the body upward and forward during the stance period. On the contrary, conventional ankle-foot ...

Au, Samuel K.

476

CDC Vital Signs: More People Walk to Better Health  

MedlinePLUS

... Read text version What Can Be Done US government is: Working with partners to carry out the ... people to be more active. State or local governments can: Consider walking when creating long-range community ...

477

Measurement of pressure walking in footwear used in leprosy.  

PubMed

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

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

1994-09-01

478

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

PubMed Central

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

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

1996-01-01

479

Dynamic Analyses of Underactuated Virtual Passive Dynamic Walking  

Microsoft Academic Search

Realization of an energy-efficient and high-speed dynamic walking has come to be one of the main subjects in the research area of robotic biped locomotion, and passive dynamic walking has been widely attracted as a clue to solve the problem. It has been empirically known that the effect of convex curve shape of foot, which characterizes passive-dynamic walkers, is important

Fumihiko Asano; Zhi-Wei Luo

2007-01-01

480

A Three-Dimensional Passive-Dynamic Walking Robot with  

Microsoft Academic Search

Abstract The authors have built the first three-dimensional, kneed, two-legged, passive-dynamic walking machine. Since the work of Tad McGeer in the late 1980s, the concept of passive dynamics has added insight into animal locomotion and the design of anthropomorphic,robots. Various analyses and machines,that demonstrate,efficient human- like walking have been developed using this strategy. Human-like passive machines, however, have only operated

Steven H. Collins; Martijn Wisse; Andy Ruina

481

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

482

Passive walker that can walk down steps: simulations and experiments  

NASA Astrophysics Data System (ADS)

A planar passive walking model with straight legs and round feet was discussed. This model can walk down steps, both on stairs with even steps and with random steps. Simulations showed that models with small moments of inertia can navigate large height steps. Period-doubling has been observed when the space between steps grows. This period-doubling has been validated by experiments, and the results of experiments were coincident with the simulation.

Liu, Ning; Li, Junfeng; Wang, Tianshu

2008-10-01

483

Central Limit Theorem for Branching Random Walks in Random Environment  

E-print Network

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

Nobuo Yoshida

2007-12-05

484

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

485

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

486

Average position in quantum walks with a U(2) coin  

E-print Network

We investigated discrete-time quantum walks with an arbitary unitary coin. Here we discover that the average position $ =\\max( \\sin(\\alpha+\\gamma)$, while the initial state is $1/\\sqrt{2}(\\mid0L>+i\\mid0R>)$. We prove the result and get some symmetry properties of quantum walks with a U(2) coin with $\\mid0L>$ and $\\mid0R>$ as the initial state.

Min Li; YOng-Sheng Zhang; Guang-Can Guo

2012-10-11

487

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

2013-01-01

488

One-dimensional random walk with phase transition  

SciTech Connect

A random walk on a one-dimensional lattice is considered. The walk is asymmetric but with different asymmetry on the right and left halves of the line. As the parameter space describing the two asymmetries is covered, several qualitatively different distributions result: limiting distribution, unimodal diffusion and biomodal diffusion. The corresponding parameter space phase boundaries are obtained, as well as the precise form of the distributions.

Percus, O.E.; Percus, J.K.

1981-06-01

489

One-dimensional random walk with phase transition  

SciTech Connect

We consider a random walk on a one-dimensional lattice. The walk is asymmetric but with different asymmetry on the right and left halves of the line. As the parameter space describing the two asymmetries is covered, several qualitatively different distributions result: limiting distribution, unimodal diffusion and bimodal diffusion. The corresponding parameter space phase boundaries are obtained, as well as the precise form of the distributions.

Percus, O.E.; Percus, J.K.

1981-06-01

490

Ising model observables and non-backtracking walks  

SciTech Connect

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

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

2014-08-15

491

The role of series ankle elasticity in bipedal walking  

PubMed Central

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

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

2014-01-01

492

The role of series ankle elasticity in bipedal walking.  

PubMed

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

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

2014-04-01

493

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

494

Walking intrusion signal recognition method for fiber fence system  

Microsoft Academic Search

A recognition method based on the gait characteristic for walking intrusion signal is presented. The gait characteristic of a normal walker in the nature state is an average gait period of 1.2s, in which a step period is about 0.6s and a foot touchdown time is about 0.2s. When a person walks fast or runs, the step period is reduced

Nian Fang; Lutang Wang; Dongjian Jia; Chao Shan; Zhaoming Huang

2009-01-01

495

Conditioned random walk with applications. [Cell growth kinetics  

Microsoft Academic Search

A random walk on the set of integers (0,1,2,...,N) with absorbing barriers at 0 and N is considered. Transition times from the points r (0 less than r less than N) are random variables with finite expectations that depend only on r. This report presents mean time to absorption at N, D\\/sub r\\/, with the condition that the walk starts

W. A. Beyer; M. S. Waterman

1978-01-01

496

Integration of human walking gyroscopic data using empirical mode decomposition.  

PubMed

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

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

2013-01-01

497

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

2013-03-01

498

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

499

Current-reinforced random walks for constructing transport networks  

PubMed Central

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.

2013-01-01

500

Integration of Human Walking Gyroscopic Data Using Empirical Mode Decomposition  

PubMed Central

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

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

2014-01-01