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1

Walking Molecules   

E-print Network

Inspired by the motor protein kinesin, an ambitious and unprecedented mimic is proposed – a synthetic molecular motor that can walk. This thesis aims to explain the basic principles which define such walking molecules, ...

Symes, Mark D

2009-01-01

2

Walk Score®  

PubMed Central

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

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

2013-01-01

3

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

4

Walking Perception by Walking Observers  

ERIC Educational Resources Information Center

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

Jacobs, Alissa; Shiffrar, Maggie

2005-01-01

5

Walking Problems  

MedlinePLUS

... your legs or feet Movement disorders such as Parkinson's disease Diseases such as arthritis or multiple sclerosis Vision or balance problems Treatment of walking problems depends on the cause. Physical ...

6

Coyote Walking  

USGS Multimedia Gallery

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

7

Quantum random walks without walking  

SciTech Connect

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.

2012-12-27

10

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

11

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

12

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

13

Stroboscopic quantum walks  

E-print Network

Discrete time (coined) quantum walks are produced by the repeated application of a constant unitary transformation to a quantum system. By recasting these walks into the setting of periodic perturbations to an otherwise freely evolving system we introduce the concept of a stroboscopic quantum walk. Through numerical simulation, we establish the link between families of stroboscopic walks and quantum resonances. These are observed in the nonlinear systems of quantum chaos theory such as the delta-kicked rotator or the delta-kicked accelerator.

Buerschaper, O

2004-01-01

14

Stroboscopic quantum walks  

E-print Network

Discrete time (coined) quantum walks are produced by the repeated application of a constant unitary transformation to a quantum system. By recasting these walks into the setting of periodic perturbations to an otherwise freely evolving system we introduce the concept of a stroboscopic quantum walk. Through numerical simulation, we establish the link between families of stroboscopic walks and quantum resonances. These are observed in the nonlinear systems of quantum chaos theory such as the delta-kicked rotator or the delta-kicked accelerator.

O. Buerschaper; K. Burnett

2004-06-29

15

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

16

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.

2012-12-13

17

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

18

Solar Photon Random Walk  

NSDL National Science Digital Library

The Solar Photon Random Walk Model simulates the path of photons in radiative transport as they escape from the Sun. Photons do not travel in a straight line, but rather collide with larger particles and get redirected. This simulation models that process using a random walk in polar coordinates. The random walk parameters are adjustable to match different models of the structure of the sun, or the user can input their own values. The Solar Photon Random Walk Model was created using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_comp_phys_photon_random_walk.jar file will run the program if Java is installed.

Onken, Ew

2011-07-26

19

6.EE Morning Walk  

NSDL National Science Digital Library

This is a task from the Illustrative Mathematics website that is one part of a complete illustration of the standard to which it is aligned. Each task has at least one solution and some commentary that addresses important asects of the task and its potential use. Here are the first few lines of the commentary for this task: Sierra walks her dog Pepper twice a day. Her evening walk is two and a half times as far as her morning walk. At the end of the week she tells her mom,...

20

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

21

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 ...

22

D.U.C.K. Walking.  

ERIC Educational Resources Information Center

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

Steller, Jenifer J.

23

Why not walk faster?  

PubMed

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

Usherwood, James Richard

2005-09-22

24

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); Claudia Veigel (National Institute for Medical Research;Division of Physical Biochemistry)

2003-06-27

25

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

26

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

27

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.

28

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

29

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

30

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

31

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.

Siegrist, Kyle

32

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

33

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

34

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

35

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

36

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".

37

Relativistic Weierstrass random walks  

NASA Astrophysics Data System (ADS)

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 tc delimiting two qualitative distinct dynamical regimes: the (nonrelativistic) superdiffusive Lévy flights, for ttc . 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.

Saa, Alberto; Venegeroles, Roberto

2010-08-01

38

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

39

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

40

Take a Planet Walk  

NSDL National Science Digital Library

Physical models in the classroom "cannot be expected to represent the full-scale phenomenon with complete accuracy, not even in the limited set of characteristics being studied" (AAAS 1990). Therefore, by modifying a popular classroom activity called a "planet walk," teachers can explore upper elementary students' current understandings; create an environment where students generate questions based on their prior knowledge; and challenge students to think critically about the accuracy and limitations of a scale model of our solar system.

Dwight Schuster

2008-09-01

41

Three movies Who we are Randomness Random walks Number walks base four Seeing walks on numbers References Seeing Things by Walking on Real Numbers  

E-print Network

Three movies Who we are Randomness Random walks Number walks base four Seeing walks on numbers on real numbers www.carma.newcastle.edu.au/walks #12;Three movies Who we are Randomness Random walks" 1 Three movies Three movies of numbers 2 Who we are The current team 3 Randomness What is Pi? What

Borwein, Jonathan

42

Biomechanics of walking with snowshoes  

Microsoft Academic Search

Snowshoeing is a popular form of winter recreation due to the development of lightweight snowshoes that provide flotation, traction, and stability. The purpose of this study was to determine the effects of snowshoes on lower extremity kinematics during level walking. Twelve adults (6 males, 6 females, body mass = 67.5 ± 10.7 kg) completed six 3-minute level walking trials. Subjects walked overground without snowshoes and

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

2012-01-01

43

Biomechanics of walking with snowshoes  

Microsoft Academic Search

Snowshoeing is a popular form of winter recreation due to the development of lightweight snowshoes that provide flotation, traction, and stability. The purpose of this study was to determine the effects of snowshoes on lower extremity kinematics during level walking. Twelve adults (6 males, 6 females, body mass = 67.5 ± 10.7 kg) completed six 3-minute level walking trials. Subjects walked overground without snowshoes and

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

2011-01-01

44

Persistence of random walk records  

NASA Astrophysics Data System (ADS)

We study records generated by Brownian particles in one dimension. Specifically, we investigate an ordinary random walk and define the record as the maximal position of the walk. We compare the record of an individual random walk with the mean record, obtained as an average over infinitely many realizations. We term the walk ‘superior’ if the record is always above average, and conversely, the walk is said to be ‘inferior’ if the record is always below average. We find that the fraction of superior walks, S, decays algebraically with time, S ˜ t-?, in the limit t ? ?, and that the persistence exponent is nontrivial, ? = 0.382?258…. The fraction of inferior walks, I, also decays as a power law, I ˜ t-?, but the persistence exponent is smaller, ? = 0.241?608…. Both exponents are roots of transcendental equations involving the parabolic cylinder function. To obtain these theoretical results, we analyze the joint density of superior walks with a given record and position, while for inferior walks it suffices to study the density as a function of position.

Ben-Naim, E.; Krapivsky, P. L.

2014-06-01

45

STEM Colorado: Random Walk  

NSDL National Science Digital Library

This applet demonstrates random walk in two dimensions. The user can specify how many particles appear at the center of the circle and the mean free path as a fraction of the radius of the circle. The path lengths are randomized with an exponential distribution. A histogram shows the number of times each particle has been deflected before it escapes the circle. It also shows the mean number of scatterings and the standard deviation. This is part of a larger collection of applets by STEM Colorado focused mostly on topics in astronomy.

Mccray, Richard; Koelemay, Andrew

2008-11-04

46

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.

47

BBC: Walking with Beasts  

NSDL National Science Digital Library

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

2008-09-04

48

Walking Tips for Older Adults  

MedlinePLUS

... started. You don’t have to worry about walking miles and miles. Slow and steady wins the race! Wear the right shoes Comfortable sneakers work well for most people, but discuss this with your doctor. Get a walking buddy Chances are you’ll stick with a ...

49

Assessment of adaptive walking performance.  

PubMed

Although mostly negative aspects are reported to be associated with gait variability, irregular walking is needed when walking performance has to be adapted to specific environmental conditions. The aim of this study was to evaluate the test-retest reliability and discriminative ability of a measure to assess adaptive walking performance and to identify parameters associated with test performance in young and elderly subjects. Eighteen older (mean age 78.1 years) and 19 young women (mean age 30.8 years) were instructed to walk as precisely as possible over a defined course targeting 26 arbitrarily positioned rectangle boxes fixed on an instrumented walk way with embedded pressure sensors. ICC(1,1) of 0.79 demonstrated sufficient reliability in the cohort of older women. Targeting was significantly worse (or deviation was larger) in older women than in young women (mean 3.20cm versus 2.27cm, p=0.005). Mean gait speed of the older women was higher during the test (0.50m/s versus 0.40m/s, p=0.020), but not during unconstrained walking (1.15m/s versus 1.50m/s, p<0.001). The deviation measure classified 78% of the subjects into correct age group (sensitivity 67%, specificity 90%, p=0.003). Adaptive walking performance was associated with parameters describing physical performance as well as with cognitive executive function. This study shows that this test of adaptive walking performance is a reliable measure of irregular walking with ability to discriminate between young and older subjects. Our results suggest that older persons might try to camouflage their lack of accuracy during adaptive walking by higher gait speed. PMID:23201276

Lindemann, U; Klenk, J; Becker, C; Moe-Nilssen, R

2013-02-01

50

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

51

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

52

Constraining walking and custodial technicolor  

SciTech Connect

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

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

2008-05-01

53

Bouchaud walks with variable drift  

E-print Network

In this paper we study a sequence of Bouchaud trap models on $\\mathbb{Z}$ with drift. We analyze the possible scaling limits for a sequence of walks, where we make the drift decay to 0 as we rescale the walks. Depending on the speed of the decay of the drift we obtain three different scaling limits. If the drift decays slowly as we rescale the walks we obtain the inverse of an \\alpha$-stable subordinator as scaling limit. If the drift decays quickly as we rescale the walks, we obtain the F.I.N. diffusion as scaling limit. There is a critical speed of decay separating these two main regimes, where a new process appears as scaling limit. This critical speed is related to the index $\\alpha$ of the inhomogeneity of the environment.

Parra, Manuel Cabezas

2010-01-01

54

Random Walk 2D Model  

NSDL National Science Digital Library

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

Christian, Wolfgang

2009-04-27

55

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 ...

56

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

57

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

58

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

59

Walkable Environments and Walking Activity  

Microsoft Academic Search

People who walk for transportation or pleasure face many challenges in the physical environment. Many people in the U.S. want to walk for utilitarian, health, or recreation purposes, but are discouraged from doing so, in part, by a lack of pedestrian facilities, an auto-dominated infrastructure (e.g., multi-lane roads that separate activity centers), and threats to their safety. While facilities for

Elizabeth Shay; Steven C. Spoon; Asad J. Khattak

60

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

61

Progressive locomotor recalibration during blind walking.  

PubMed

Blind walking has become a common measure of perceived target location. This article addresses the possibility that blind walking might vary systematically within an experimental session as participants accrue exposure to nonvisual locomotion. Such variations could complicate the interpretation of blind walking as a measure of perceived location. We measured walked distance, velocity, and pace length in indoor and outdoor environments (1.5-16.0 m target distances). Walked distance increased over 37 trials by approximately 9.33% of the target distance; velocity (and to a lesser extent, pace length) also increased, primarily in the first few trials. In addition, participants exhibited more unintentional forward drift in a blindfolded marching-in-place task after exposure to nonvisual walking. The results suggest that participants not only gain confidence as blind-walking exposure increases, but also adapt to nonvisual walking in a way that biases responses toward progressively longer walked distances. PMID:19064490

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

2008-11-01

62

Correlated Markov Quantum Walks  

E-print Network

We consider the discrete time unitary dynamics given by a quantum walk on $\\Z^d$ performed by a particle with internal degree of freedom, called coin state, according to the following iterated rule: a unitary update of the coin state takes place, followed by a shift on the lattice, conditioned on the coin state of the particle. We study the large time behavior of the quantum mechanical probability distribution of the position observable in $\\Z^d$ for random updates of the coin states of the following form. The random sequences of unitary updates are given by a site dependent function of a Markov chain in time, with the following properties: on each site, they share the same stationnary Markovian distribution and, for each fixed time, they form a deterministic periodic pattern on the lattice. We prove a Feynman-Kac formula to express the characteristic function of the averaged distribution over the randomness at time $n$ in terms of the nth power of an operator $M$. By analyzing the spectrum of $M$, we show that this distribution posesses a drift proportional to the time and its centered counterpart displays a diffusive behavior with a diffusion matrix we compute. Moderate and large deviations principles are also proven to hold for the averaged distribution and the limit of the suitably rescaled corresponding characteristic function is shown to satisfy a diffusion equation. An example of random updates for which the analysis of the distribution can be performed without averaging is worked out. The random distribution displays a deterministic drift proportional to time and its centered counterpart gives rise to a random diffusion matrix whose law we compute. We complete the picture by presenting an uncorrelated example.

Eman Hamza; Alain Joye

2011-10-21

63

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

64

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

E-print Network

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

Peterson, Jonathon

65

Base Station Walk-Back  

NSDL National Science Digital Library

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

Center, Nasa J.

2012-06-26

66

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

67

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 made) in the next few years? What do you anticipate that price might be?

Ellis, Katharine

68

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

69

Walk Booklets Date: June 2010 Monash Campus Walks  

E-print Network

on to Commercial Road and turn right, following it along until the famous Chapel Street. On your way, you will pass mins Exit the Alfred Hospital onto Commercial Road, cross the road and turn right. Take the first. This walk gives is an excellent round trip of Fawkner Park. Once you reach Commercial road again, cross over

Albrecht, David

70

Limit Theorems for the Fibonacci Quantum Walk  

E-print Network

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

Clement Ampadu

2011-08-25

71

3. Introduction 16. Short Random Walks  

E-print Network

16. Short Random Walks 17. Combinatorics 23. Meijer-G functions 28. Hypergeometric values of W3, W43. Introduction 16. Short Random Walks 40. Multiple Mahler Measures 47. Log-sine Integrals Mahler Measures, Short Walks and Log-sine Integrals A case study in hybrid computation Jonathan M. Borwein frsc

Borwein, Jonathan

72

4. Introduction 17. Short Random Walks  

E-print Network

17. Short Random Walks 18. Combinatorics 24. Meijer-G functions 29. Hypergeometric values of W3, W44. Introduction 17. Short Random Walks 41. Multiple Mahler Measures 48. Log-sine Integrals Mahler Measures, Short Walks and Log-sine Integrals A case study in hybrid computation Jonathan M. Borwein frsc

Borwein, Jonathan

73

Walk Across Texas! and Texas Education Agency  

E-print Network

Walk Across Texas! and Texas Education Agency Partnership http://walkacrosstexas.tamu.edu Walk Across Texas! is an eight-week program to help people of all ages support one another to establish the habit of regular physical activity. Walk Across Texas! is recognized as a Best Practice Physical

74

Walking practice and suburban nature-talk  

Microsoft Academic Search

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

Gordon Waitt; Nicholas Gill; Lesley Head

2009-01-01

75

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

76

A walk in the woods  

Microsoft Academic Search

Life is a sequence of tiny events and most of us feel that our days are pretty ordinary. Chris Farbrother's article is a simple description of going for a walk. That's all. But perhaps it hints at the benefits of exercise, the healing power of the countryside and the triumph of small achievements.

Christine Farbrother

2003-01-01

77

Science Sampler: Walking Out Graphs  

NSDL National Science Digital Library

In the Walking Out Graphs Lesson described here, students experience several types of representations used to describe motion, including words, sentences, equations, graphs, data tables, and actions. The most important theme of this lesson is that students have to understand the consistency among these representations and form the habit of transforming among these representation (Shen and Confrey 2007).

Ji Shen

2009-12-01

78

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.

79

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

80

Evanescence in coined quantum walks  

Microsoft Academic Search

In this paper, we complete the analysis begun by two of the authors in a previous work on the discrete quantum walk on the infinite line (Carteret et al2003 J. Phys. A: Math. Gen.36 8775–95). We obtain uniformly convergent asymptotics for the ‘exponential decay’ regions at the leading edges of the main peaks in the Schrdinger (or wave mechanics) picture.

Hilary A. Carteret; Bruce Richmond; Nico M Temme

2005-01-01

81

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.

82

Monkeys and Walks Muhammad Waliji  

E-print Network

Monkeys and Walks Muhammad Waliji August 12, 2006 1 Preliminaries We will be dealing with outcomes is independent. 2 The Infinite-Monkey Theorem Before we state the infinite-monkey theorem, we will prove a useful speaking, the infinite-monkey theorem states that if a monkey hits keys on a typewriter at random

May, J. Peter

83

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

84

Clairvoyant scheduling of random walks  

E-print Network

´acs (BU) Clairvoyant demon April 25, 2008 1 / 65 #12;Introduction The clairvoyant demon problem 0 1 2 3 4 nodes. In each instant, either X or Y will move. A demon knows both (infinite) walks completely . . ., Y = 0012111443 . . .. The repetitions are the demon's insertions. P´eter G´acs (BU) Clairvoyant

Gacs, Peter

85

Age of walking and mental retardation.  

PubMed Central

The age of independent walking was noted for 200 retarded children aged 30-60 months living in the community. The onset of walking tended to be later in more severely retarded children, but early walkers were found even among the most retarded. The majority of children with mild, moderate, and severe retardation walked by 17 months. Only in the group which was profoundly retarded did the majority begin to walk after 17 months. Onset of walking before 17 months is usual in retarded children and is compatible with all levels of mental retardation. Images FIGURE 1 PMID:6881409

Kaminer, R K; Jedrysek, E

1983-01-01

86

Faster transport with a directed quantum walk  

NASA Astrophysics Data System (ADS)

We give an example of faster transport with a quantum walk on an inherently directed graph, on the directed line with a variable number of self-loops at each vertex. These self-loops can be thought of as adding a number of small dimensions. This is a discrete time quantum walk using the Fourier transform coin, where the walk proceeds a distance ?(1) in constant time compared to ?(1/n) classically, independent of the number of these small dimensions. The analysis proceeds by reducing this walk to a walk with a two-dimensional coin.

Hoyer, Stephan; Meyer, David A.

2009-02-01

87

Full revivals in 2D quantum walks  

NASA Astrophysics Data System (ADS)

Recurrence of a random walk is described by the Pólya number. For quantum walks, recurrence is understood as the return of the walker to the origin, rather than the full revival of its quantum state. Localization for two-dimensional quantum walks is known to exist in the sense of non-vanishing probability distribution in the asymptotic limit. We show, on the example of the 2D Grover walk, that one can exploit the effect of localization to construct stationary solutions. Moreover, we find full revivals of a quantum state with a period of two steps. We prove that there cannot be longer cycles for a four-state quantum walk. Stationary states and revivals result from interference, which has no counterpart in classical random walks.

Štefa?ák, M.; Kollár, B.; Kiss, T.; Jex, I.

2010-09-01

88

Machines that walk: The adaptive suspension vehicle  

Microsoft Academic Search

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

Shin-Min Song; Kenneth J. Waldron

1989-01-01

89

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

90

Motor modules in robot-aided walking  

PubMed Central

Background It is hypothesized that locomotion is achieved by means of rhythm generating networks (central pattern generators) and muscle activation generating networks. This modular organization can be partly identified from the analysis of the muscular activity by means of factorization algorithms. The activity of rhythm generating networks is described by activation signals whilst the muscle intervention generating network is represented by motor modules (muscle synergies). In this study, we extend the analysis of modular organization of walking to the case of robot-aided locomotion, at varying speed and body weight support level. Methods Non Negative Matrix Factorization was applied on surface electromyographic signals of 8 lower limb muscles of healthy subjects walking in gait robotic trainer at different walking velocities (1 to 3km/h) and levels of body weight support (0 to 30%). Results The muscular activity of volunteers could be described by low dimensionality (4 modules), as for overground walking. Moreover, the activation signals during robot-aided walking were bursts of activation timed at specific phases of the gait cycle, underlying an impulsive controller, as also observed in overground walking. This modular organization was consistent across the investigated speeds, body weight support level, and subjects. Conclusions These results indicate that walking in a Lokomat robotic trainer is achieved by similar motor modules and activation signals as overground walking and thus supports the use of robotic training for re-establishing natural walking patterns. PMID:23043818

2012-01-01

91

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; Mcgath, Gary; Trunfio, Paul

2009-12-16

92

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

93

Random walks between leaves of random networks  

NASA Astrophysics Data System (ADS)

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

Lancaster, David

2014-02-01

94

Limit theorems for open quantum random walks  

E-print Network

We consider the limit distributions of open quantum random walks on one-dimensional lattice space. We introduce a dual process to the original quantum walk process, which is quite similar to the relation of Schr\\"odinger-Heisenberg representation in quantum mechanics. By this, we can compute the distribution of the open quantum random walks concretely for many examples and thereby we can also obtain the limit distributions of them. In particular, it is possible to get rid of the initial state when we consider the evolution of the walk, it appears only in the last step of the computation.

Norio Konno; Hyun Jae Yoo

2012-09-06

95

State machine-based controller for walk-halt-walk transitions on a biped robot  

Microsoft Academic Search

In this paper, we show how it is possible to obtain a walk - standup - walk cycle with a biped robot using only a state machine controller. This work is a continuation of another in which the same approach was used to control the walking gait of the same robot. We introduce four critical angles that affect robot speed

H. Serhan; P. Henaff; C. Nasr; F. Ouezdou

2008-01-01

96

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

E-print Network

On the Levy-walk Nature of Human Mobility: Do Humans Walk like Monkeys? Injong Rhee, Minsu Shin under existing mobility models. I. INTRODUCTION Do humans walk like monkeys? It is not about upright mobility have similar statistical patterns as monkeys? This paper pro- vides statistical evidence

Young, R. Michael

97

Gaitography applied to prosthetic walking.  

PubMed

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

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

2014-11-01

98

Science Sampler: Walk this way  

NSDL National Science Digital Library

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

Fechheim, Jan; Nelson, John

2007-02-01

99

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

100

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

101

4. Introduction 17. Short Random Walks  

E-print Network

-G functions 29. Hypergeometric values of W3, W4 32. Probability and Bessel J 40. Derivative values of W3, W4 34. Introduction 17. Short Random Walks 41. Multiple Mahler Measures 48. Log-sine Integrals Mahler Measures, Short Walks and Log-sine Integrals A case study in hybrid computation Jonathan M. Borwein frsc

Borwein, Jonathan

102

Multilinear decomposition of human walking paths  

Microsoft Academic Search

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

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

2010-01-01

103

Power Demand for Walking on the Treadmill  

NSDL National Science Digital Library

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

Hageseth, Gaylord T.

2000-02-01

104

Nonrandom walks in monkeys and humans  

Microsoft Academic Search

Principles of self-organization play an increasingly central role in models of human activity. Notably, individual human displacements exhibit strongly recurrent patterns that are characterized by scaling laws and can be mechanistically modelled as self-attracting walks. Recurrence is not, however, unique to human displacements. Here we report that the mobility patterns of wild capuchin monkeys are not random walks and exhibit

Denis Boyer; Margaret C. Crofoot; Peter D. Walsh

2011-01-01

105

Quantum Walks and Reversible Cellular Automata  

E-print Network

We investigate a connection between a property of the distribution and a conserved quantity for the reversible cellular automaton derived from a discrete-time quantum walk in one dimension. As a corollary, we give a detailed information of the quantum walk.

Norio Konno; Kenichi Mitsuda; Takahiro Soshi; Hyun Jae Yoo

2004-07-13

106

Walk-off correction in biaxial crystals  

NASA Astrophysics Data System (ADS)

A comprehensive model has been developed to construct phase matching conditions, including Poynting vector directions, parametrically interacting beam wavelengths, relative walk-off angles and polarization states in a biaxial nonlinear single crystal with known refractive index dispersion. The model optimizes phase matching conditions by providing a strategy for walk-off compensation that determines the optimum periodicity of twist-twin Adhesive-Free Bond (AFB(R)) composite pair designs. The model is validated experimentally by measuring the calculated walk-off angles and the crystal orientation of KTP that correlates to the given Poynting vector. The method is useful in reducing uncertainties of OPO designs, in providing walk-off compensation design data, and in confirming the final walk-off corrected design configuration. It is generally applicable to biaxial and uniaxial nonlinear crystals.

Lee, H.-C.; Meissner, H. E.

2007-10-01

107

Gait attentional load at different walking speeds.  

PubMed

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

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

2015-01-01

108

Information Dimension of Dissipative Quantum Walks  

E-print Network

We study the temporal growth of the von Neumann entropy for dissipative quantum walks on networks. By using a phenomenological quantum master equation, the quantum stochastic walk (QSW), we are able to parametrically scan the crossover from purely coherent quantum walks to purely diffusive random walks. In the latter limit the entropy shows a logarithmic growth, which is proportional to the information dimension of the random walk on the network. Here we present results for the von Neumann entropy based on the reduced density operator of the QSW. It shows a similar logarithmic growth for a wide range of parameter values and networks. As a consequence, we propose the logarithmic growth rate of the von Neumann entropy to be a natural extension of the information dimension to dissipative quantum systems. We corroborate our results by comparing to numerically exact simulations.

P. Schijven; O. Muelken

2014-08-13

109

Decoherence in quantum walks - a review  

E-print Network

The development of quantum walks in the context of quantum computation, as generalisations of random walk techniques, led rapidly to several new quantum algorithms. These all follow unitary quantum evolution, apart from the final measurement. Since logical qubits in a quantum computer must be protected from decoherence by error correction, there is no need to consider decoherence at the level of algorithms. Nonetheless, enlarging the range of quantum dynamics to include non-unitary evolution provides a wider range of possibilities for tuning the properties of quantum walks. For example, small amounts of decoherence in a quantum walk on the line can produce more uniform spreading (a top-hat distribution), without losing the quantum speed up. This paper reviews the work on decoherence, and more generally on non-unitary evolution, in quantum walks and suggests what future questions might prove interesting to pursue in this area.

Viv Kendon

2006-11-26

110

The 2-min walk test is sufficient for evaluating walking abilities in sporadic inclusion body myositis.  

PubMed

Sporadic inclusion body myositis causes progressive functional loss due to declining muscle strength. Although the underlying cause is unknown, clinical trials are underway to improve strength and function. Selection of appropriate outcome measures is critical for the success of these trials. The 6-min walk test has been the de facto standard for assessing function in neuromuscular disease; however, the optimal walking test has not been determined in this disease. In this study, 67 individuals with sporadic inclusion body myositis completed a battery of quantitative strength and functional tests including timed walking tests, patient-reported outcomes, and other tasks. The 2-min and 6-min walk tests are highly correlated to each other (r=0.97, p<0.001) and to all lower extremity strength, patient-reported, and functional measures in this population. All subjects completed the 2-min walk test, but 7% of subjects were unable to walk the full 6-min of the 6-min walk test due to fatigue. The 2-min walk test demonstrates similar correlation to all outcomes compared to the 6-min walk test, is less fatiguing and better tolerated. Results suggest that the 2-min walk test is a better alternative to tests of longer duration. Further research is needed to determine longitudinal changes on this outcome. PMID:24342281

Alfano, L N; Lowes, L P; Dvorchik, I; Yin, H; Maus, E G; Flanigan, K M; Mendell, J R

2014-03-01

111

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

112

Symbolic walk in regular networks  

NASA Astrophysics Data System (ADS)

We find that a symbolic walk (SW)—performed by a walker with memory given by a Bernoulli shift—is able to distinguish between the random or chaotic topology of a given network. We show this result by means of studying the undirected baker network, which is defined by following the Ulam approach for the baker transformation in order to introduce the effect of deterministic chaos into its structure. The chaotic topology is revealed through the central role played by the nodes associated with the positions corresponding to the shortest periodic orbits of the generating map. They are the overwhelmingly most visited nodes in the limit cycles at which the SW asymptotically arrives. Our findings contribute to linking deterministic chaotic dynamics with the properties of networks constructed using the Ulam approach.

Ermann, Leonardo; Carlo, Gabriel G.

2015-01-01

113

Medical Aspects of Space Walking  

NASA Technical Reports Server (NTRS)

Dr. Musgrave has acquired extensive experience during a distinguished and impressive career that includes flying as an astronaut on six Shuttle missions, participating in many hours of extravehicular activity, and contributing his myriad talents toward great public service, especially in the area of education. He has a unique perspective as a physician, scientist, engineer, pilot, and scholar. His interests and breadth of knowledge, which astound even the seasoned space enthusiast, have provided the space program an extraordinary scientific and technical expertise. Dr. Musgrave presented a personal perspective on space flight with particular emphasis on extravehicular activity (EVA or space walking), which was copiously illustrated with photographs from many space missions. His theme was two fold: the exacting and detailed preparations required for successful execution of a mission plan and a cosmic view of mankind's place in the greater scheme of things.

Musgrave, Story

1999-01-01

114

Walking after Stroke: Comfortable versus Maximum Safe Speed.  

ERIC Educational Resources Information Center

This study attempted to (1) determine whether stroke patients (n=20) can safely increase their walking speed above that of comfortable walking; (2) describe the relationship between comfortable and maximum safe walking speed; and (3) examine correlations between maximum and comfortable speeds and a functional walking score. Subjects were able to…

Bohannon, Richard W.

1992-01-01

115

Urban Walking and the Pedagogies of the Street  

ERIC Educational Resources Information Center

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

Bairner, Alan

2011-01-01

116

Neighborhood Walkability and the Walking Behavior of Australian Adults  

Microsoft Academic Search

Background: The physical attributes of residential neighborhoods, particularly the connectedness of streets and the proximity of destinations, can influence walking behaviors. To provide the evidence for public health advocacy on activity-friendly environments, large-scale studies in different countries are needed. Associations of neighborhood physical environments with adults' walking for transport and walking for recreation must be better understood. Method: Walking for

Neville Owen; Ester Cerin; Eva Leslie; Lawrence D. Frank; Adrian E. Bauman; Graeme Hugo; Brian E. Saelens; James F. Sallis

2007-01-01

117

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

118

Stabilization control for humanoid robot to walk on inclined plane  

Microsoft Academic Search

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

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

2008-01-01

119

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

120

Limit cycle walking on a regularized ground  

E-print Network

The singular nature of contact problems, such as walking, makes them difficult to analyze mathematically. In this paper we will "regularize" the contact problem of walking by approximating the ground with a smooth repulsive potential energy and a smooth dissipative friction force. Using this model we are able to prove the existence of a limit cycle for a periodically perturbed system which consists of three masses connected by springs. In particular, this limit cycle exists in a symmetry reduced phase. In the unreduced phase space, the motion of the masses resembles walking.

Jacobs, Henry O

2012-01-01

121

Quantum Walk with a Bit Flip  

E-print Network

We point out that the quantum (Hadamard) walk remains invariant, except for a spatial inversion, when the unitary shift operator is augmented by a bit flip operation in the coin space. The augmented version is in fact equivalent to the conventional quantum walk with an initial bit flip. This simple observation is relevant to the implementation of quantum walks in physical systems where a flip of the coin state accompanies the translation in position Hilbert space when the conditional shift operator is applied. We consider in particular a Bose-Einstein condensate system.

Chandrasekhar, C M

2006-01-01

122

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

Code of Federal Regulations, 2011 CFR

...walk-in coolers and walk-in freezers. 431.304 Section 431.304 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION ENERGY EFFICIENCY PROGRAM FOR CERTAIN COMMERCIAL AND INDUSTRIAL EQUIPMENT Walk-in Coolers and Walk-in...

2011-01-01

123

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

Code of Federal Regulations, 2010 CFR

...walk-in coolers and walk-in freezers. 431.304 Section 431.304 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION ENERGY EFFICIENCY PROGRAM FOR CERTAIN COMMERCIAL AND INDUSTRIAL EQUIPMENT Walk-in Coolers and Walk-in...

2010-01-01

124

STP Random Walk 1D Continuous Program  

NSDL National Science Digital Library

The RandomWalk1DContinuous program simulates a random walk in one dimension for steps of any length between 0 and 1. The default number of steps is N = 16 and the probability p of going to the right for a single step is 0.5. RandomWalk1DContinuous is part of a suite of Open Source Physics programs that model aspects of Statistical and Thermal Physics (STP). The program is distributed as a ready-to-run (compiled) Java archive. Double clicking the stp RandomWalk1DContinuous.jar file will run the program if Java is installed on your computer. Additional programs can be found by searching ComPADRE for Open Source Physics, STP, or Statistical and Thermal Physics.

Gould, Harvey; Tobochnik, Jan; Christian, Wolfgang; Cox, Anne

2008-10-10

125

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 ...

126

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 ...

127

STP Random Walk 1D Program  

NSDL National Science Digital Library

The RandomWalk1D program simulates a random walk in one dimension for steps of unit length and equal time intervals. The default number of steps is N = 16 and the probability of going right or left at any step is the same (the probability p of going to the right for a single step is 0.5). RandomWalk1D is part of a suite of Open Source Physics programs that model aspects of Statistical and Thermal Physics (STP). The program is distributed as a ready-to-run (compiled) Java archive. Double clicking the stp RandomWalk1D.jar file will run the program if Java is installed on your computer. Additional programs can be found by searching ComPADRE for Open Source Physics, STP, or Statistical and Thermal Physics.

Gould, Harvey; Tobochnik, Jan; Christian, Wolfgang; Cox, Anne

2008-10-10

128

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

129

Minimal walking technicolor: Setup for collider physics  

SciTech Connect

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

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

2007-09-01

130

STP Random Walk 2D Program  

NSDL National Science Digital Library

The RandomWalk2D program simulates a random walk in two dimensions. The default number of walkers is 1000, and the probability of going right, left up or down at any step is the same. RandomWalk2D is part of a suite of Open Source Physics programs that model aspects of Statistical and Thermal Physics (STP). The program is distributed as a ready-to-run (compiled) Java archive. Double clicking the stp RandomWalk2D.jar file will run the program if Java is installed on your computer. Additional programs can be found by searching ComPADRE for Open Source Physics, STP, or Statistical and Thermal Physics.

Gould, Harvey; Tobochnik, Jan; Christian, Wolfgang; Cox, Anne

2008-10-10

131

STP Random Walk 2D SAW Program  

NSDL National Science Digital Library

The RandomWalkSAW program simulates a self-avoiding random walk in two dimensions. The walker has an equal probability of going in any direction, but cannot return to a site that has already been visited. The default number of initial walkers is 100 and the total number of steps N = 1024. RandomWalkSAW is part of a suite of Open Source Physics programs that model aspects of Statistical and Thermal Physics (STP). The program is distributed as a ready-to-run (compiled) Java archive. Double clicking the stp RandomWalkSAW.jar file will run the program if Java is installed on your computer. Additional programs can be found by searching ComPADRE for Open Source Physics, STP, or Statistical and Thermal Physics.

Gould, Harvey; Tobochnik, Jan; Christian, Wolfgang; Cox, Anne

2008-10-10

132

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

133

Walk, Haydel Approach to Process Heat Recovery  

E-print Network

Walk, Haydel has developed a two phase approach to optimize the recovery of process heat in energy intensive operations. While the approach can be used on 'grassroots' designs, it has been used primarily for revamps. The capital investment...

Waldsmith, R. W.; Hendrickson, M. J.

1983-01-01

134

Sensory dysfunction in children who toe walk.  

PubMed

In order to formulate a hypothesis regarding the etiology of toe walking, the sensory processing abilities of 17 mentally retarded children who toe walk were examined. A galvanic skin response was used to compare reactions of the mentally retarded children and a group of normal children to a variety of sensory stimuli. Galvanic skin response testing did not reveal significant differences between the two groups in processing sensory input. Scores of the mentally retarded children from a postrotary nystagmus test were compared to values for normal children of the same age, and the results indicated that vestibular dysfunction was present in all of the subjects. We hypothesize that children may toe walk to increase somatosensory input to the lateral vestibular nucleus (Deiter's) and the lateral vestibulospinal tract to facilitate support tone in the lower extremities during walking. PMID:693578

Montgomery, P; Gauger, J

1978-10-01

135

Power Demand in Walking and Pace Optimization.  

ERIC Educational Resources Information Center

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

Bellemans, A.

1981-01-01

136

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.

137

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

138

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

139

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.

140

Does getting a dog increase recreational walking?  

Microsoft Academic Search

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

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

2008-01-01

141

Ranger Robot: 9 km walk 9 kilometers  

E-print Network

·Evolvability #12;Ranger design: Overview #12;Inner ankle: 4.5W Hip: 6WElectronics: 8W Outer ankle: 4.5W Power usage by Ranger motors and electronics ­ straight walk Outer ankle motor power is 7.5W during turns energy use by operation: inner or outer ankle Straight walking ­ no turns Hip swing energy is 4J #12;Flip

Ruina, Andy L.

142

Self-avoiding walks with writhe  

Microsoft Academic Search

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 ? ? 0.588) a small chemical potential for writhe is irrelevant and the Chern-Simons field does not modify the monomer-monomer

J. David Moroz; Randall D. Kamien

1997-01-01

143

Equal Superposition Transformations and Quantum Random Walks  

E-print Network

The largest ensemble of qubits which satisfy the general transformation of equal superposition is obtained by different methods, namely, linearity, no-superluminal signalling and non-increase of entanglement under LOCC. We also consider the associated quantum random walk and show that all unitary balanced coins give the same asymmetric spatial probability distribution. It is further illustrated that unbalanced coins, upon appropriate superposition, lead to new unbiased walks which have no classical analogues.

Preeti Parashar

2007-09-21

144

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

145

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

146

Design of a walking robot  

NASA Astrophysics Data System (ADS)

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

1994-03-01

147

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

148

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

149

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

150

Metabolic response to graded downhill walking.  

PubMed

Compared with level walking or running, progressive downhill walking or running requires a decreasing energy cost to some minimum where the cost again increases with further decrements in grade. Margaria estimated this minimum occurs at a -9% grade. In this study an attempt was made to more precisely track the energy cost curve in progressive downhill treadmill walking. Ten men, mean age 22.0 +/- 2.5 yr, volunteered as subjects. After VO2max determinations the subjects attended two downhill walking sessions. Each subject performed 14 randomly ordered walking bouts of 6 min in duration, at speeds of 90 and 105 m.min-1. The grades used were 0, -3, -6, -9, -12, -15, and -18%. Gas exchange measurements were obtained by open circuit spirometry during each work bout. Heart rate was monitored continuously and the stride frequency was counted by direct observation during each walking bout. Net VO2 values decreased with decrements in grade to -9, -12% for the respective speeds of 90 and 105 m.min-1. The group mean net VO2 minimums at -9 and -12%, however, were not significantly different (P > 0.05) from the group mean values at -6 and -15% at 90 m.min-1, or between -9 and -15% grades at 105 m.min-1, Group mean net VO2 values at 0, -3, and -18% were significantly different (P < 0.05) from net VO2 values for the other grades at 90 m.min-1 walking. At 105 m.min-1, mean net VO2 values at 0, -3, -6, and -18% were significantly different (P < 0.05) from net VO2 values at the other grades.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8423750

Wanta, D M; Nagle, F J; Webb, P

1993-01-01

151

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

152

Vection in depth during treadmill walking.  

PubMed

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

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

2013-01-01

153

Gait characteristics when walking with rounded soft sole shoes.  

PubMed

This study aimed to examine the effect of shoes with a rounded soft sole (Stretch Walker: SW) on gait. Fifteen healthy male (mean age: 23.2) walked under three conditions (SW, Flat-bottomed Shoe: FS, Barefoot: BF). Including walking speed, stance time, step length were selected as temporal-spatial parameters. The angle of hip, knee, and ankle joints during particular phases were selected as kinematic parameters. Walking speed, stance time, step length and flexion angle of the ankle joint at initial contact were greater when wearing either shoe than walking BF; cadence was faster walking BF than wearing either shoe; double support time increased (FS>SW>BF); step width was greater (FS>SW>BF); walking angle was greater wearing the SW than wearing the FS and walking BF; and range of motion and maximum flexion angle of the hip and knee joints were greater wearing the FS than walking BF. In conclusion, wearing the SW with a heel-to-toe rocker and soft sole changes the double support time, step width, and walking angle and increases step length and walking speed compared to walking BF. The difference of the range of motion in hip and knee joints was larger between walking BF and wearing the FS than between walking BF and wearing the SW. PMID:22079403

Demura, Tomohiro; Demura, Shin-ichi; Yamaji, Shunsuke; Yamada, Takayoshi; Kitabayashi, Tamotsu

2012-03-01

154

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 scale-free networks. 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, and moreover, some features 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

2015-01-01

155

[Use of walk tests in pulmonology].  

PubMed

Functional assessment is an obligatory part of examination of patients with chronic respiratory diseases. Ergospirometry is a "gold standard" of functional examination of the cardiorespiratory system. Walk tests are alternative to ergospirometry and can be performed outside laboratories of functional diagnosis. A 6-min walk test provides information on functional condition, treatment efficacy and prognosis in many diseases of the heart and lungs. The result of this test under 350 m suggests a high risk of death. However this test has a serious defect--an insignificant result in weak motivation of the patient. The defects of a 6-min walk test can be corrected by the shuttle-test with growing or permanent load. The test with growing load measures physical performance, while that with permanent load estimates the ability to endure long-term loading. PMID:22708426

2012-01-01

156

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

PubMed

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

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

2014-07-18

157

Idiopathic toe walking and sensory processing dysfunction  

PubMed Central

Background It is generally understood that toe walking involves the absence or limitation of heel strike in the contact phase of the gait cycle. Toe walking has been identified as a symptom of disease processes, trauma and/or neurogenic influences. When there is no obvious cause of the gait pattern, a diagnosis of idiopathic toe walking (ITW) is made. Although there has been limited research into the pathophysiology of ITW, there has been an increasing number of contemporary texts and practitioner debates proposing that this gait pattern is linked to a sensory processing dysfunction (SPD). The purpose of this paper is to examine the literature and provide a summary of what is known about the relationship between toe walking and SPD. Method Forty-nine articles were reviewed, predominantly sourced from peer reviewed journals. Five contemporary texts were also reviewed. The literature styles consisted of author opinion pieces, letters to the editor, clinical trials, case studies, classification studies, poster/conference abstracts and narrative literature reviews. Literature was assessed and graded according to level of evidence. Results Only one small prospective, descriptive study without control has been conducted in relation to idiopathic toe walking and sensory processing. A cross-sectional study into the prevalence of idiopathic toe walking proposed sensory processing as being a reason for the difference. A proposed link between ITW and sensory processing was found within four contemporary texts and one conference abstract. Conclusion Based on the limited conclusive evidence available, the relationship between ITW and sensory processing has not been confirmed. Given the limited number and types of studies together with the growing body of anecdotal evidence it is proposed that further investigation of this relationship would be advantageous. PMID:20712877

2010-01-01

158

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

159

Improving homology estimates with random walks  

NASA Astrophysics Data System (ADS)

This experimental paper makes the case for a new approach to the use of persistent homology in the study of shape and feature in datasets. By introducing ideas from diffusion geometry and random walks, we discover that homological features can be enhanced and more effectively extracted from spaces that are sampled densely and evenly, and with a small amount of noise. This study paves the way for a more theoretical analysis of how random walk metrics affect persistence diagrams, and provides evidence that combining topological data analysis with techniques inspired by diffusion geometry holds great promise for new analyses of a wide variety of datasets.

Bendich, Paul; Galkovskyi, Taras; Harer, John

2011-12-01

160

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

161

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...

162

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

163

Walking for therapy with man's best friend.  

PubMed

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

Cangelosi, Pamela R; Sorrell, Jeanne M

2010-03-01

164

Mind your step: Metabolic energy cost while walking an enforced gait pattern  

Microsoft Academic Search

The energy cost of walking could be attributed to energy related to the walking movement and energy related to balance control. In order to differentiate between both components we investigated the energy cost of walking an enforced step pattern, thereby perturbing balance while the walking movement is preserved.Nine healthy subjects walked three times at comfortable walking speed on an instrumented

D. Wezenberg; A. de Haan; C. A. M. van Bennekom; H. Houdijk

2011-01-01

165

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

166

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 walking, largely at the transitions between steps. The ankle then acts to restore energy during push-off, which may be the reason that ankle impairment nearly always leads to poorer walking economy

Collins, Steven H.

167

Angular Momentum Regulation during Human Walking: Biomechanics and Control  

Microsoft Academic Search

Motivated by biomechanical studies on human walking, we present a control strategy for biologically realistic walking based on the principle of spin angular momentum regulation. Using a morphologically realistic human model and kinematic gait data, we compute the total spin angular momentum at a self-selected walking speed for one human test subject. We find that dimensionless spin angular momentum remains

Marko Popovic; Andreas Hofmann; Hugh Herr

2004-01-01

168

Walking and the Preservation of Cognitive Function in Older Populations  

ERIC Educational Resources Information Center

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

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

2009-01-01

169

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

170

The efficiency and walking speed of visually impaired people  

Microsoft Academic Search

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

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

1986-01-01

171

A random-walk approach to interference  

Microsoft Academic Search

In this paper we sketch a probabilistic particle approach requiring no separate concept of wave to obtain interference. We describe in some detail how things work from a physical standpoint and show with a number of figures how the standard wave concepts are developed from purely particle random walks. For the wave concepts we have in each case a matching

Patrick Suppes; J. Acacio de Barros

1994-01-01

172

A Random Walk on a Circular Path  

ERIC Educational Resources Information Center

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

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

2005-01-01

173

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.

Park, Smithsonian N.

2012-06-26

174

Improving homology estimates with random walks  

Microsoft Academic Search

This experimental paper makes the case for a new approach to the use of persistent homology in the study of shape and feature in datasets. By introducing ideas from diffusion geometry and random walks, we discover that homological features can be enhanced and more effectively extracted from spaces that are sampled densely and evenly, and with a small amount of

Paul Bendich; Taras Galkovskyi; John Harer

2011-01-01

175

Multibody Simulation Model of Human Walking  

Microsoft Academic Search

A three-dimensional simulational model of a human walking is presented. The biped is anthropomorphic, i.e., its inertial and kinematical properties are similar to human ones. The biped consists of eight rigid bodies. Each leg consists of three parts: thigh, shank, and foot. The trunk is modeled as two rigid bodies connected by a revolute joint. The inertia properties of head

Marek Wojtyra

2003-01-01

176

RANDOM WALKS ON LIE GROUPS E. BREUILLARD  

E-print Network

ratio limit theorems and local limit theorems in this c* *ontext. We give several examples including the It^o-Kawada equidistribution theorem for* * compact groups and the local limit theorem for random in the * *classical local limit theorem. Although such random walks have been very thoroughly studi* *ed in the past

Breuillard, Emmanuel

177

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

178

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

179

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...

180

Development of Miniaturized Walking Biological Machines  

E-print Network

cut into various shapes. When released, the thin films curled or twisted into 3D conformationsDevelopment of Miniaturized Walking Biological Machines Vincent Chan1,5 , Kidong Park2,5 , Mitchell-engineer' and fabricate biological machines remains a grand challenge. Towards this end, we have fabricated locomotive

Bashir, Rashid

181

The walk and jump of Equisetum spores  

PubMed Central

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

Marmottant, Philippe; Ponomarenko, Alexandre; Bienaimé, Diane

2013-01-01

182

Modelling of contact in walking machines  

Microsoft Academic Search

Presents the results of modelling, simulation and measurements of contact forces between the legs and the ground of the six-legged robot HERMESTM during a slow walk. The kinematics and dynamics of HERMESTM (transient analysis) was simulated using an insect locomotion scheme. In the dynamical model three contact-impact models were considered. In the first approach the model was built using a

J. Fraczek; A. Morecki

1999-01-01

183

Random Walks and Catalan Factorization Omer Egecioglu  

E-print Network

of California Santa Barbara, CA 93106, U.S.A. omer@cs.ucsb.edu Alastair King, Abdus Salam I.C.T.P., Strada Costiera 11, 34014 Trieste, Italy. a.king@ictp.trieste.it Abstract In the theory of random walks

King, Alastair

184

Impacts of Car Sharing on Walking Behavior  

Microsoft Academic Search

Car sharing, now being offered in about 30 cities in North America, and perhaps 50 organizations throughout Europe, provides convenient short-term automobile use without car ownership. A number of studies indicate that car sharing members use public transit, walk and bicycle at higher rates that the general population. This paper and presentation provide a summary of the impact of car

Steven Scott; Dave Brook; Matei Perussi

185

The walk and jump of Equisetum spores.  

PubMed

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

Marmottant, Philippe; Ponomarenko, Alexandre; Bienaimé, Diane

2013-11-01

186

Exotic states of bouncing and walking droplets  

NASA Astrophysics Data System (ADS)

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

Wind-Willassen, Øistein; Molá?ek, Jan; Harris, Daniel M.; Bush, John W. M.

2013-08-01

187

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

188

Communities, Random Walks, and Social Sybil Defense  

E-print Network

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

Alvisi, Lorenzo

189

Screenbot: Walking inverted using distributed inward gripping  

Microsoft Academic Search

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

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

2008-01-01

190

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

191

Sunspot random walk and 22-year variation  

NASA Astrophysics Data System (ADS)

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

Love, Jeffrey J.; Rigler, E. Joshua

2012-05-01

192

Biomechanics of walking, running, and sprinting  

Microsoft Academic Search

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

Roger A. Mann; John Hagy

1980-01-01

193

Toolbox Safety Talk Walking/Working Surfaces  

E-print Network

are usually relatively simple, such as keeping walkways and stairs clear of debris, coiling up extension cords, and clearing parking lots, stairs, and walkways in snowy weather. The following provides information on walking are to be placed on roofing structures, employees must determine the safe load capacity before taking this action

Pawlowski, Wojtek

194

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

195

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

196

Clairvoyant scheduling of random walks Peter Gacs  

E-print Network

the two 1 #12;2 0 1 2 3 4 Y : WAIT X : GO Figure 1: The clairvoyant demon problem. X,Y are "tokens" performing independent ran- dom walks on the same graph: here the complete graph K5. A "demon" decides every the clairvoyant demon problem, arose first in distributed computing. The original problem was to find a leader

Gacs, Peter

197

Random walk centrality for temporal networks  

E-print Network

Nodes can be ranked according to their relative importance within the 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, as 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 which we call TempoRank. While in a static network, the stationary density of the random walk is proportional to the degree or the strength of a node, we find that in temporal networks, the stationary density is proportional to the in-strength of the so-called effective network. The stationary density also depends on the sojourn probability q which regulates the tendency of the walker to stay in the node. We apply our method to human interaction networks and show that although it is important for a node ...

Rocha, Luis Enrique Correa

2014-01-01

198

Exploring Space and Place with Walking Interviews  

ERIC Educational Resources Information Center

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

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

2008-01-01

199

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

200

NetLogo Models Library: Random Walk 360  

NSDL National Science Digital Library

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

Wilensky, Uri

201

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

202

Relationships between Muscle Contributions to Walking Subtasks and Functional Walking Status in Persons with Post-Stroke Hemiparesis  

PubMed Central

Background Persons with post-stroke hemiparesis usually walk slowly and asymmetrically. Stroke severity and functional walking status are commonly predicted by post-stroke walking speed. The mechanisms that limit walking speed, and by extension functional walking status, need to be understood to improve post-stroke rehabilitation methods. Methods Three-dimensional forward dynamics walking simulations of hemiparetic subjects (and speed-matched controls) with different levels of functional walking status were developed to investigate the relationships between muscle contributions to walking subtasks and functional walking status. Muscle contributions to forward propulsion, swing initiation and power generation were analyzed during the pre-swing phase of the gait cycle and compared between groups. Findings Contributions from the paretic leg muscles (i.e., soleus, gastrocnemius and gluteus medius) to forward propulsion increased with improved functional walking status, with the non-paretic leg muscles (i.e., rectus femoris and vastii) compensating for reduced paretic leg propulsion in the limited community walker. Contributions to swing initiation from both paretic (i.e., gastrocnemius, iliacus and psoas) and non-paretic leg muscles (i.e., hamstrings) also increased as functional walking status improved. Power generation was also an important indicator of functional walking status, with reduced paretic leg power generation limiting the paretic leg contribution to forward propulsion and leg swing initiation. Interpretation These results suggest that deficits in muscle contributions to the walking subtasks of forward propulsion, swing initiation and power generation are directly related to functional walking status and that improving output in these muscle groups may be an effective rehabilitation strategy for improving post-stroke hemiparetic walking. PMID:21251738

Hall, A.L.; Peterson, C.L.; Kautz, S.A.; Neptune, R.R.

2011-01-01

203

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

204

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

205

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

206

Generalized ruin problems and asynchronous random walks  

NASA Astrophysics Data System (ADS)

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

Abad, E.

2005-07-01

207

Dynamics of Human Walking at Steady Speeds  

NASA Astrophysics Data System (ADS)

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

Kokshenev, Valery B.

2004-11-01

208

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

209

Individual characteristics of human walking mechanics  

Microsoft Academic Search

Twenty-four subjects walked at different speeds (V) from 0.4 to 2.6 m s–1, while motion and ground reaction forces were recorded in 3-D space. The total mechanical energy of each body segment was\\u000a computed as the sum of the gravitational potential, translation and rotation kinetic energies. Energy profiles reveal that\\u000a there are inter-individual differences, particularly at moderate and fast V.

L. Bianchi; D. Angelini; F. Lacquaniti

1998-01-01

210

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

211

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

212

Fractal landscape analysis of DNA walks  

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

213

Neighborhood Design for Walking and Biking  

PubMed Central

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

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

2013-01-01

214

Walking While Talking and Falls in Aging  

PubMed Central

Background While divided attention tasks are recognized as predictors of falls in older adults, a comprehensive examination of this association is lacking. Objective We examined the validity of a ‘walking while talking (WWT)’ task for predicting falls. Methods We studied the associations of eight selected gait markers measured during WWT (individually as well as domains derived by factor analysis) with incident falls in 646 adults (mean age 79.9, 61% women) enrolled in an aging study who received quantitative gait assessments. Cox regressions adjusted for multiple potential confounders and normal pace walking were used to examine the associations. Results Over a mean follow-up of 2.6 years, 337 participants (52%) fell. Step length was the only individual WWT parameter that predicted falls (HR 0.98, p=0.034). Factor analysis identified three gait domains, of which only the pace factor predicted falls (HR 1.31, p=0.002). Results remained robust after adjusting for multiple potential confounders and accounting for normal pace walking. Conclusions WWT performance was a significant predictor of falls. Gait domains in WWT should be further studied to improve current fall risk assessments and to develop new interventions. PMID:24192342

Ayers, Emmeline I.; Tow, Amanda C.; Holtzer, Roee; Verghese, Joe

2013-01-01

215

The variability problem of normal human walking.  

PubMed

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

Simonsen, Erik B; Alkjær, Tine

2012-03-01

216

Decoherence in two-dimensional quantum walks  

NASA Astrophysics Data System (ADS)

We analyze the decoherence in quantum walks in two-dimensional lattices generated by broken-link-type noise. In this type of decoherence, the links of the lattice are randomly broken with some given constant probability. We obtain the evolution equation for a quantum walker moving on two-dimensional (2D) lattices subject to this noise, and we point out how to generalize for lattices in more dimensions. In the nonsymmetric case, when the probability of breaking links in one direction is different from the probability in the perpendicular direction, we have obtained a nontrivial result. If one fixes the link-breaking probability in one direction, and gradually increases the probability in the other direction from 0 to 1, the decoherence initially increases until it reaches a maximum value, and then it decreases. This means that, in some cases, one can increase the noise level and still obtain more coherence. Physically, this can be explained as a transition from a decoherent 2D walk to a coherent 1D walk.

Oliveira, A. C.; Portugal, R.; Donangelo, R.

2006-07-01

217

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

218

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

219

Asymptotic properties of a bold random walk  

NASA Astrophysics Data System (ADS)

In a recent paper we proposed a non-Markovian random walk model with memory of the maximum distance ever reached from the starting point (home). The behavior of the walker is different from the simple symmetric random walk only when she is at this maximum distance, where, having the choice to move either farther or closer, she decides with different probabilities. If the probability of a forward step is higher than the probability of a backward step, the walker is bold and her behavior turns out to be superdiffusive; otherwise she is timorous and her behavior turns out to be subdiffusive. The scaling behavior varies continuously from subdiffusive (timorous) to superdiffusive (bold) according to a single parameter ? ?R. We investigate here the asymptotic properties of the bold case in the nonballistic region ? ?[0,1/2], a problem which was left partially unsolved previously. The exact results proved in this paper require new probabilistic tools which rely on the construction of appropriate martingales of the random walk and its hitting times.

Serva, Maurizio

2014-08-01

220

Asymptotic properties of a bold random walk.  

PubMed

In a recent paper we proposed a non-Markovian random walk model with memory of the maximum distance ever reached from the starting point (home). The behavior of the walker is different from the simple symmetric random walk only when she is at this maximum distance, where, having the choice to move either farther or closer, she decides with different probabilities. If the probability of a forward step is higher than the probability of a backward step, the walker is bold and her behavior turns out to be superdiffusive; otherwise she is timorous and her behavior turns out to be subdiffusive. The scaling behavior varies continuously from subdiffusive (timorous) to superdiffusive (bold) according to a single parameter ??R. We investigate here the asymptotic properties of the bold case in the nonballistic region ??[0,1/2], a problem which was left partially unsolved previously. The exact results proved in this paper require new probabilistic tools which rely on the construction of appropriate martingales of the random walk and its hitting times. PMID:25215703

Serva, Maurizio

2014-08-01

221

Asymptotic properties of a bold random walk  

E-print Network

In a recent paper we proposed a non-Markovian random walk model with memory of the maximum distance ever reached from the starting point (home). The behavior of the walker is at variance with respect to the simple symmetric random walk (SSRW) only when she is at this maximum distance, where, having the choice to move either farther or closer, she decides with different probabilities. If the probability of a forward step is higher then the probability of a backward step, the walker is bold and her behavior turns out to be super-diffusive, otherwise she is timorous and her behavior turns out to be sub-diffusive. The scaling behavior vary continuously from sub-diffusive (timorous) to super-diffusive (bold) according to a single parameter $\\gamma \\in R$. We investigate here the asymptotic properties of the bold case in the non ballistic region $\\gamma \\in [0,1/2]$, a problem which was left partially unsolved in \\cite{S}. The exact results proved in this paper require new probabilistic tools which rely on the construction of appropriate martingales of the random walk and its hitting times.

Maurizio Serva

2014-06-13

222

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

223

Daily intermittent hypoxia enhances walking after chronic spinal cord injury  

PubMed Central

Objectives: To test the hypothesis that daily acute intermittent hypoxia (dAIH) and dAIH combined with overground walking improve walking speed and endurance in persons with chronic incomplete spinal cord injury (iSCI). Methods: Nineteen subjects completed the randomized, double-blind, placebo-controlled, crossover study. Participants received 15, 90-second hypoxic exposures (dAIH, fraction of inspired oxygen [Fio2] = 0.09) or daily normoxia (dSHAM, Fio2 = 0.21) at 60-second normoxic intervals on 5 consecutive days; dAIH was given alone or combined with 30 minutes of overground walking 1 hour later. Walking speed and endurance were quantified using 10-Meter and 6-Minute Walk Tests. The trial is registered at ClinicalTrials.gov (NCT01272349). Results: dAIH improved walking speed and endurance. Ten-Meter Walk time improved with dAIH vs dSHAM after 1 day (mean difference [MD] 3.8 seconds, 95% confidence interval [CI] 1.1–6.5 seconds, p = 0.006) and 2 weeks (MD 3.8 seconds, 95% CI 0.9–6.7 seconds, p = 0.010). Six-Minute Walk distance increased with combined dAIH + walking vs dSHAM + walking after 5 days (MD 94.4 m, 95% CI 17.5–171.3 m, p = 0.017) and 1-week follow-up (MD 97.0 m, 95% CI 20.1–173.9 m, p = 0.014). dAIH + walking increased walking distance more than dAIH after 1 day (MD 67.7 m, 95% CI 1.3–134.1 m, p = 0.046), 5 days (MD 107.0 m, 95% CI 40.6–173.4 m, p = 0.002), and 1-week follow-up (MD 136.0 m, 95% CI 65.3–206.6 m, p < 0.001). Conclusions: dAIH ± walking improved walking speed and distance in persons with chronic iSCI. The impact of dAIH is enhanced by combination with walking, demonstrating that combinatorial therapies may promote greater functional benefits in persons with iSCI. Classification of evidence: This study provides Class I evidence that transient hypoxia (through measured breathing treatments), along with overground walking training, improves walking speed and endurance after iSCI. PMID:24285617

Hayes, Heather B.; Jayaraman, Arun; Herrmann, Megan; Mitchell, Gordon S.; Rymer, William Z.

2014-01-01

224

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

PubMed Central

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

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

2013-01-01

225

The effects of clothes on independent walking in toddlers.  

PubMed

The spatiotemporal features of walking in toddlers are known to be related to the level of maturation of the central nervous system. However, previous studies did not assess whether there could be an effect of clothes on the acquisition of walking. In this study, it was hypothesized that clothes modify the toddlers' walking. To test this hypothesis, 22 healthy toddlers divided into 3 groups of walking experience were assessed in four clothing conditions (Diaper+Trousers; Diaper+Pants of tracksuit; Diaper; Underwear). Results revealed significant effects of clothing on velocity and step length of toddlers from 6 to 18 months of walking experience. These results suggested that biomechanical constraints induced by the textile features alter the walking of toddlers. Therefore, in studies of toddler's gait, the clothing worn should be carefully mentioned and controlled. PMID:24054348

Théveniau, Nicolas; Boisgontier, Matthieu P; Varieras, Sabine; Olivier, Isabelle

2014-01-01

226

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

227

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

228

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

229

Random Walks of Magnetic Bright Points and Coronal Loop Heating  

Microsoft Academic Search

The random walks of small-scale ( ~ 0.2 arcsec) magnetic bright points (MBPs) in the lanes between photospheric granules are anomalous. The temporal growth of the q-th moment of the displacement r(t) is a power law with exponent q gamma (q)\\/2. For normal, Gaussian walks gamma (q)= 1 for all q. However, for the MBP walks on time scales <

J. K. Lawrence; A. C. Cadavid; A. A. Ruzmaikin

2000-01-01

230

Walking Pattern Generator Using an Evolutionary Central Pattern Generator  

Microsoft Academic Search

\\u000a For the generation of locomotion, such as walking, running or swimming, vertebrate and invertebrate animals use the Central\\u000a PatternGenerator (CPG). In this paper, a walking pattern generator is proposed using an evolutionary optimized CPG. Sensory\\u000a feedback pathways in CPG are proposed, which uses Force Sensing Resistor (FSR) signals. For the optimization of CPG parameters,\\u000a quantuminspired evolutionary algorithm is employed. Walking

Chang-Soo Park; Jeong-Ki Yoo; Young-Dae Hong; Ki-Baek Lee; Si-Jung Ryu; Jong-Hwan Kim

2010-01-01

231

Assessing walking speed in clinical research: a systematic review  

PubMed Central

Objective To provide a systematic review and describe how assessments of walking speed are reported in the health care literature. Methods MEDLINE electronic database and bibliographies of select articles were searched for terms describing walking speed and distances walked. The search was limited to English language journals from 1996 to 2006. The initial title search yielded 793 articles. A review of the abstracts reduced the number to 154 articles. Of these, 108 provided sufficient information for inclusion in the current review. Results Of the 108 studies included in the review 61 were descriptive, 39 intervention and 8 randomized controlled trials. Neurological (n = 55) and geriatric (n = 27) were the two most frequent participant groups in the studies reviewed. Instruction to walk at a usual or normal speed was reported in 55 of the studies, while 31 studies did not describe speed instructions. A static (standing) start was slightly more common than a dynamic (rolling) start (30 vs 26 studies); however, half of the studies did not describe the starting protocol. Walking 10, 6 and 4 m was the most common distances used, and reported in 37, 20 and 11 studies respectively. Only four studies included information on whether verbal encouragement was given during the walking task. Conclusions Tests of walking speed have been used in a wide range of populations. However, methodologies and descriptions of walking tests vary widely from study to study, which makes comparison difficult. There is a need to find consensus for a standardized walking test methodology. PMID:18462283

Graham, James E.; Ostir, Glenn V.; Fisher, Steven R.; Ottenbacher, Kenneth J.

2009-01-01

232

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

233

Bridging the gulf between correlated random walks and Lévy walks: autocorrelation as a source of Lévy walk movement patterns  

PubMed Central

For many years, the dominant conceptual framework for describing non-oriented animal movement patterns has been the correlated random walk (CRW) model in which an individual's trajectory through space is represented by a sequence of distinct, independent randomly oriented ‘moves’. It has long been recognized that the transformation of an animal's continuous movement path into a broken line is necessarily arbitrary and that probability distributions of move lengths and turning angles are model artefacts. Continuous-time analogues of CRWs that overcome this inherent shortcoming have appeared in the literature and are gaining prominence. In these models, velocities evolve as a Markovian process and have exponential autocorrelation. Integration of the velocity process gives the position process. Here, through a simple scaling argument and through an exact analytical analysis, it is shown that autocorrelation inevitably leads to Lévy walk (LW) movement patterns on timescales less than the autocorrelation timescale. This is significant because over recent years there has been an accumulation of evidence from a variety of experimental and theoretical studies that many organisms have movement patterns that can be approximated by LWs, and there is now intense debate about the relative merits of CRWs and LWs as representations of non-orientated animal movement patterns. PMID:20630882

Reynolds, Andy M.

2010-01-01

234

Light dilaton in walking gauge theories  

SciTech Connect

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

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

2010-10-01

235

Field Theories of Topological Random Walks  

E-print Network

In this work we derive certain topological theories of transverse vector fields whose amplitudes reproduce topological invariants involving the interactions among the trajectories of three and four random walks. This result is applied to the construction of a field theoretical model which describes the statistical mechanics of an arbitrary number of topologically linked polymers in the context of the analytical approach of Edwards. With respect to previous attempts, our approach is very general, as it can treat a system involving an arbitrary number of polymers and the topological states are not only specified by the Gauss linking number, but also by higher order topological invariants.

Franco Ferrari; Ignazio Lazzizzera

1999-06-14

236

Thermodynamic behavior of the quantum walk  

NASA Astrophysics Data System (ADS)

A thermodynamic theory is developed to describe the behavior of the entanglement between the coin and position degrees of freedom of the quantum walk on the line. It is shown that, in spite of the unitary evolution, a steady state is established after a Markovian transient stage. This study suggests that if a quantum dynamics develops in a composite Hilbert space (i.e., the tensor product of several subspaces), then the behavior of an operator that belongs only to one of the subspaces may camouflage the unitary character of the global evolution.

Romanelli, Alejandro

2012-01-01

237

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 $\\alpha\\in(1,2]$ then the spectral dimension of the looptree is $2\\alpha/(\\alpha+1)$.

Björnberg, Jakob E.; Stefánsson, Sigurdur Örn

2015-01-01

238

Let Your Ears Do the Walking  

NSDL National Science Digital Library

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

Engineering K-Phd Program

239

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

240

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

241

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

242

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

243

Random walk on random infinite looptrees  

E-print Network

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 $\\alpha\\in(1,2]$ then the spectral dimension of the looptree is $2\\alpha/(\\alpha+1)$.

Jakob E. Björnberg; Sigurdur Örn Stefánsson

2014-02-24

244

Pier Walk '97: The Electronic Version  

NSDL National Science Digital Library

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

1997-01-01

245

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 L.

2007-12-12

246

Active Walks and Increasing Returns in Economics  

NASA Astrophysics Data System (ADS)

Active walk (AW) is a paradigm for pattern formation and self-organization in complex systems, footnote "Introduction to Nonlinear Physics," edited by L. Lam (Springer, 1997) applicable to many natural systems (such as the formation of filamentary patterns in retinal neurons and surface reaction patterns in thin cells of fluids, anomalous ion transport in glasses, and food collection by ant swarms) and social systems (such as urban development, biological evolution, and economics).footnote L. Lam, "Nonlinear Physics for Beginners" (World Scientific, 1998) Here, after a brief review of AW, an AW model for increasing returns in economics is introduced. Computer results and analytic solutions will be presented.

Lam, L.

1998-03-01

247

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

248

WINDINGS OF PLANAR RANDOM WALKS AND AVERAGED DEHN FUNCTION  

E-print Network

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

Paris-Sud XI, Université de

249

The Fibonacci quantum walk and its cassical trace map  

E-print Network

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

Alejandro Romanelli

2008-02-15

250

Emulating Human Leg Impairments and Disabilities on Humanoid Robots Walking  

E-print Network

Emulating Human Leg Impairments and Disabilities on Humanoid Robots Walking S´ebastien Lengagne for emulating human walking motions with leg impairments or disabilities using humanoid robots. Our optimal dynamic multi-contact motion software generates the emulated motions. We take into account the full

Paris-Sud XI, Université de

251

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

252

Optimized Joint-Torques Trajectory Planning for Bipedal Walking Robots  

Microsoft Academic Search

This paper proposes a new method of trajectory planning for biped robots walking on flat terrain. In this approach, the hip and foot trajectories are designed in Cartesian space using polynomial interpolation. The key parameters which define the hip and foot trajectories are searched by genetic algorithm. The objective is to obtain stable walking trajectory with minimized joint-torques requirement. ZMP

Van-huan Dau; Chee-Meng Chewt; Aun-neow Poo

2008-01-01

253

Limit theorem for random walk in weakly dependent random scenery  

E-print Network

: Random walks; random scenery; weak dependence; limit theorem; local time. AMS Subject ClassificationLimit theorem for random walk in weakly dependent random scenery Nadine Guillotin-Plantard and Cl on the scenery we prove a functional limit theorem generalizing Kesten and Spitzer's theorem (1979). Keywords

Paris-Sud XI, Université de

254

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

PubMed Central

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

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

2014-01-01

255

Guiding Students through Expository Text with Text Feature Walks  

ERIC Educational Resources Information Center

The Text Feature Walk is a structure created and employed by the authors that guides students in the reading of text features in order to access prior knowledge, make connections, and set a purpose for reading expository text. Results from a pilot study are described in order to illustrate the benefits of using the Text Feature Walk over…

Kelley, Michelle J.; Clausen-Grace, Nicki

2010-01-01

256

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

257

Energy Cost during Prolonged Walking vs Jogging Exercise.  

ERIC Educational Resources Information Center

This study of nine young men compared the energy expended, substrates used, and perception of effort from brisk walking and jogging at the same target heart rates. Jogging utilized more total energy and fat energy than walking and was perceived as less strenuous. Oxygen pulse was higher during jogging. (Author/SM)

Thomas, Tom R.; Londeree, Ben R.

1989-01-01

258

Learning to Walk in 20 Minutes Russ Tedrake  

E-print Network

Institute. through the unilateral, intermittent, uncertain force contacts with the ground. The walking the convex hull of the ground contact points during some portion of the walking cycle. Achieving stable configuration of the robot. Second, details of the robot dynamics such as uncertainties in the ground contact

Tedrake, Russ

259

Medial gastrocnemius muscle behavior during human running and walking  

Microsoft Academic Search

Utilization of elastic energy in the tendinous tissues (TT) of the human skeletal muscle may be task dependent. The present study was designed to investigate this problem by comparing the fascicle-TT interaction of the medial gastrocnemius muscle (MG) during ground contact of running and walking. Seven subjects ran and walked with a natural cadence. Ankle and knee joint angular data

M. Ishikawa; J. Pakaslahti; P. V. Komi

2007-01-01

260

Limiting Distributions and Large Deviations for Random Walks in ...  

E-print Network

My life has been blessed in so many ways by things that are ... 2.1.2 Recursions for Hitting Times and a Law of Large Numbers. ..... (traps) where the potential is increasing (which means the random walk is more likely to move ..... allow the walk to backtrack more than log2(n) ladder times (that is, we deal with a dynamically.

2008-07-21

261

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

262

Humanoid Robot Walking Control on Inclined Planes Utku Seven1  

E-print Network

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

Yanikoglu, Berrin

263

Random walk lengths of about 30 years in global climate  

Microsoft Academic Search

We have applied the relation for the mean of the expected values of the maximum excursion in a bounded random walk to estimate the random walk length from time series of eight independent global mean quantities (temperature maximum, summer lag, temperature minimum and winter lag in land and over the ocean) derived from the NOAA-CIRES twentieth century reanalysis (V2) for

John Bye; Klaus Fraedrich; Edilbert Kirk; Silke Schubert; Xiuhua Zhu

2011-01-01

264

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

265

The advantages of a rolling foot in human walking  

Microsoft Academic Search

The plantigrade human foot rolls over the ground during each walking step, roughly analogous to a wheel. The center of pressure progresses on the ground like a wheel of radius 0.3·L (leg length). We examined the effect of varying foot curvature on the mechanics and energetics of walking. We controlled curvature by attaching rigid arc shapes of various radii to

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

2006-01-01

266

Chinese City Children and Youth's Walking Behavior  

ERIC Educational Resources Information Center

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

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

2013-01-01

267

Humanoid Walking Robot: Modeling, Inverse Dynamics, and Gain Scheduling Control  

E-print Network

trajectories, recorded from real human walking cycle data. Kinematic and dynamic analysis is discussed, including the model kinematics, dynamics and controls, with numerical solution simulations for desired joint1 Humanoid Walking Robot: Modeling, Inverse Dynamics, and Gain Scheduling Control Elvedin Kljuno

Williams II, Robert L.

268

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

269

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

270

Random walk with priorities in communicationlike networks  

NASA Astrophysics Data System (ADS)

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

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

2013-08-01

271

[From walk test to cardiopulmonary exercise test].  

PubMed

Cardiopulmonary exercise test is a new respiratory functional test used for sick children. It demonstrates the integrated response of all the systems involved in exercise (especially cardiac and respiratory ones) and consequently evaluates exercise adaptations during chronic disease. This dynamic test assesses exercise tolerance, and so quality of life more objectively than a resting test. Values measured (especially oxygen uptake and ventilatory threshold) are quantifiable and reproducible, allowing the follow-up of a disease and the initiation and individualization of exercise training. Moreover, it is also useful for diagnosis and assessment of abnormal symptoms during exercise (as dyspnea), especially abnormalities that are undetectable during rest. The six-minute walk test, the step test and the shuttle test are rapid, simple and low-cost field tests that give adequate information on the daily physical performance (walking, climbing stairs, or running) of the sick child. They allow a closed follow-up, especially during an exercise training period. However, only the cardio-pulmonary exercise test can allow the physical practise in sick children, eliminating the contra-indications. PMID:18280913

Karila, C

2007-12-01

272

Stilt walking: how do we learn those first steps?  

PubMed

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

Akram, Sakineh B; Frank, James S

2009-09-01

273

Factors affecting age of walking by children with mental retardation.  

PubMed

The relationship between age of walking and two factors of severity of intellectual disability and clinical types (autism, Down syndrome, epilepsy, and "residual") in children with mental retardation was investigated. Subjects were 118 children whose disabilities ranged from severe to mild. Measures by clinical type were significant, and the differences of any two clinical types except between children with epilepsy and the "residual" group were significant, but severity of intellectual disability was not significant. Most children with autism (27 subjects, 93%) walked by the normal time limit of 18 months. Only 3 children (11%) with Down syndrome began to walk within that limit, and 9 of them (33%) walked after 2 years of age. In the "residual" group (including children with epilepsy), 37 children (60%) walked within the normal limit but 15 (25%) only after 2 years of age. PMID:7675588

Kokubun, M; Haishi, K; Okuzumi, H; Hosobuchi, T

1995-04-01

274

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

275

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

PubMed

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

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

2010-06-01

276

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.

277

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

Federal Register 2010, 2011, 2012, 2013, 2014

...Energy Conservation Program: Test Procedures for Walk-In Coolers...Energy Conservation Program: Test Procedures for Walk-In Coolers...Office of General Counsel's Web site, http://www.gc.doe.gov. DOE reviewed the test procedures considered in...

2010-09-09

278

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

279

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

280

Differences in Ground Reaction Forces and Shock Impacts Between Nordic Walking and Walking.  

PubMed

The regular practice of Nordic walking (NW) has increased in recent years, in part thanks to the health benefits described by the scientific literature. However, there is no consensus on the effects of shock-impact absorption during its practice. Purpose: The aim of this study was to compare the levels of impact and ground reaction forces (GRF) between NW and walking (W). Method: Twenty physically active and experienced participants were assessed using a dynamometric platform and accelerometry analysis. Results: The results show statistically significantly higher levels of acceleration in the tibia (12%) and head (21%) during NW compared with W. Equally, GRF were significantly higher (27%) at the instant of strike compared with W, and a reduction of the forces at the instant of takeoff (8%) was observed. Conclusions: During NW, shock impacts and GRF levels increased compared with W, an aspect that should be considered when prescribing health improvement programs. PMID:25386664

Encarnación-Martínez, Alberto; Pérez-Soriano, Pedro; Llana-Belloch, Salvador

2014-11-11

281

Thermodynamics of N-dimensional quantum walks  

E-print Network

The entanglement between the position and coin state of a $N$-dimensional quantum walker is shown to lead to a thermodynamic theory. The entropy, in this thermodynamics, is associated to the reduced density operator for the evolution of chirality, taking a partial trace over positions. From the asymptotic reduced density matrix it is possible to define thermodynamic quantities, such as the asymptotic entanglement entropy, temperature, Helmholz free energy, etc. We study in detail the case of a $2$-dimensional quantum walk, in the case of two different initial conditions: a non-separable coin-position initial state, and a separable one. The resulting entanglement temperature is presented as function of the parameters of the system and those of the initial conditions.

Alejandro Romanelli; Raul Donangelo; Renato Portugal; Franklin L. Marquezino

2014-08-22

282

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

283

Astronaut Noguchi During STS-114 Space Walk  

NASA Technical Reports Server (NTRS)

Launched on July 26, 2005 from the Kennedy Space Center in Florida, STS-114 was classified as Logistics Flight 1. Among the Station-related activities of the mission were the delivery of new supplies and the replacement of one of the orbital outpost's Control Moment Gyroscopes (CMGs). STS-114 also carried the Raffaello Multi-Purpose Logistics Module (MPLM) and the External Stowage Platform-2. In this photograph, astronaut Soichi Noguchi, STS-114 mission specialist representing the Japan Aerospace Exploration Agency (JAXA), participates in the mission's first scheduled session of Extra Vehicular Activity (EVA). Noguchi and crew mate Stephen K. Robinson (out of frame) completed a demonstration of Shuttle thermal protection repair techniques and enhancements to the ISS's attitude control system during the successful 6 hour, 50 minute space walk.

2005-01-01

284

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

285

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

286

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

287

Foot trajectory approximation using the pendulum model of walking.  

PubMed

Generating a natural foot trajectory is an important objective in robotic systems for rehabilitation of walking. Human walking has pendular properties, so the pendulum model of walking has been used in bipedal robots which produce rhythmic gait patterns. Whether natural foot trajectories can be produced by the pendulum model needs to be addressed as a first step towards applying the pendulum concept in gait orthosis design. This study investigated circle approximation of the foot trajectories, with focus on the geometry of the pendulum model of walking. Three able-bodied subjects walked overground at various speeds, and foot trajectories relative to the hip were analysed. Four circle approximation approaches were developed, and best-fit circle algorithms were derived to fit the trajectories of the ankle, heel and toe. The study confirmed that the ankle and heel trajectories during stance and the toe trajectory in both the stance and the swing phases during walking at various speeds could be well modelled by a rigid pendulum. All the pendulum models were centred around the hip with pendular lengths approximately equal to the segment distances from the hip. This observation provides a new approach for using the pendulum model of walking in gait orthosis design. PMID:24057114

Fang, Juan; Vuckovic, Aleksandra; Galen, Sujay; Conway, Bernard A; Hunt, Kenneth J

2014-01-01

288

Oxygen Cost During Treadmill Walking with Hip and Knee Immobilised  

PubMed Central

The aim of this study was to determine the effect of immobilising the knee and hip on the oxygen cost (ml·kg-1·min-1) to velocity relationship during treadmill walking. The study was a prospective experimental conducted in a Rehabilitation centre. Ten healthy individuals, five men and five women, with no gait abnormality participated. Following familiarisation five men and five women walked on a treadmill and selected their own, free “comfortable walking velocity ”(SSWS). Subjects then performed an incremental test at -60 to +60% of SSWS. Individuals later repeated the test with the knee and hip of one limb immobilised. Samples of expired air were measured at each velocity and the oxygen cost (ml·kg-1·min-1) to Froude number (Fr) relationship plotted (where calculation of Fr normalizes for subjects of differing leg length and acts as an index of velocity). There was a higher oxygen cost, and lower Fr at SSWS during immobilised (0.21 ± 0.03 ml·kg-1·min-1; Fr = 0.12 ± 0. 03) compared with free walking (0.16 ± 0.02 ml·kg-1·min-1; Fr = 0.18 ± 0.04) (p < 0. 01). Statistical analysis demonstrated that during immobilised walking an inverse fit (y = ?0 + ?1/x) and for free walking a cubic fit (y = ?0 + ?1x + ?2x2 + ?3x3) best fitted the data. Hip and knee immobilisation increased the oxygen cost at SSWS and altered the oxygen cost to Fr relationship. The results have implications in selecting optimal walking velocities in individuals with impairments affecting mobility such as hemiplegic gait. Key Points Walking with one limb immobilised requires greater energy cost than normal free walking. This has clinical implications when developing rehabilitation strategies for patients who mobility problems such as those with hemi paretic gait. PMID:24357960

Elsworth, Charlotte; Dawes, Helen; Collett, Johnny; Howells, Ken; Ramsbottom, Roger; Izadi, Hooshang; Sackley, Cath

2006-01-01

289

Tae Kwon Do: An Effective Exercise for Improving Balance and Walking Ability in Older Adults  

Microsoft Academic Search

Background. Age-related declines in balance and walking ability are major risk factors for falls. Older adults reduce the dynamic components of walking in an effort to achieve a more stable walking pattern. Tae Kwon Do is an exercise that trains dynamic components of balance and walking that diminish with age. Methods. Twenty participants from a Tae Kwon Do exercise class

Ronita L. Cromwell; Paul M. Meyers; Paul E. Meyers; Roberta A. Newton

2007-01-01

290

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

Microsoft Academic Search

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

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

2006-01-01

291

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

292

Complete stability analysis of a control law for walking robots with non-permanent contacts  

E-print Network

of the main specificities of walking robots is their non-permanent contact with the ground which impairs of the position and contact forces of a walking robot. 2 Position and force regulation law for walking robots We of the position and contact forces of a walking robot. This work was supported by the European project SICONOS IST

Paris-Sud XI, Université de

293

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

ERIC Educational Resources Information Center

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

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

2009-01-01

294

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

PubMed Central

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

Hubel, Tatjana Y.; Usherwood, James R.

2013-01-01

295

A local limit theorem for random walks in balanced environments  

E-print Network

Central limit theorems for random walks in quenched random environments have attracted plenty of attention in the past years. More recently still, finer local limit theorems -- yielding a Gaussian density multiplied by a highly oscillatory modulating factor -- for such models have been obtained. In the one-dimensional nearest-neighbor case with i.i.d. transition probabilities, local limits of uniformly elliptic ballistic walks are now well understood. We complete the picture by proving a similar result for the only recurrent case, namely the balanced one, in which such a walk is diffusive. The method of proof is, out of necessity, entirely different from the ballistic case.

Mikko Stenlund

2013-03-06

296

Quantum walk-based search and symmetries in graphs  

NASA Astrophysics Data System (ADS)

In this paper we present a lemma, which helps us to establish a link between the distribution of success probabilities from quantum walk based search and the symmetries of the underlying graphs. With the aid of the lemma, we identified certain graph structures of which the quantum walk based search provides high success probabilities at the marked vertices. We also observed that many graph structures and their vertices can be classified according to their structural equivalence using the search probabilities provided by quantum walks, although this method cannot resolve all non-equivalent vertices for strongly regular graphs.

Mahasinghe, A.; Wang, J. B.; Wijerathna, J. K.

2014-12-01

297

Walk dimension for light in complex disordered media  

NASA Astrophysics Data System (ADS)

Transport in complex systems is characterized by a fractal dimension—the walk dimension—that indicates the diffusive or anomalous nature of the underlying random walk process. Here we report on the experimental retrieval of this key quantity, using light waves propagating in disordered media. The approach is based on measurements of the time-resolved transmission, in particular on how the lifetime scales with sample size. We show that this allows one to retrieve the walk dimension and apply the concept to samples with varying degree of fractal heterogeneity. In addition, the method provides the first experimental demonstration of anomalous light dynamics in a random medium.

Savo, Romolo; Burresi, Matteo; Svensson, Tomas; Vynck, Kevin; Wiersma, Diederik S.

2014-08-01

298

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

299

Step rate-determined walking intensity and walking recommendation in Chinese young adults: a cross-sectional study  

PubMed Central

Abstract There is lack of data on the physiological characteristics of over ground walking and walking recommendations for Chinese young adult. The purpose of the study was to measure walking-related energy expenditure during field testing, to identify step-rate cut-point associated with moderate and vigorous intensity, and to translate physical activity (PA) guidelines into walking goals for Chinese young adults. Design Cross-sectional analytic study. Setting Two communities from Beijing and Shanghai in China. Participants A sample of 226 Chinese adults (117 men, 109 women) with a mean age of 21.7 (±0.2) years, volunteered to participate in the study. All Participants were recreationally active without orthopaedic limitations, free of chronic diseases, not taking any medications that affect metabolism and non-smokers. Outcome measures All the participants completed four 6?minincremental over ground walking at different speeds of 3.8, 4.8, 5.6 and 6.4?km/h, respectively. Indirect calorimeter was used to measure energy expenditure at each speed. Receiver operating characteristic curves were used to determine the step-rate cut-points associated with moderate and vigorous intensity activity. Results At the same walking speed, step counts per minute were higher in women than in men. No significant differences were found in VO2 per weight (ml/kg/min) between women and men. Step-rate cut-point associated with walking at 3 metabolic equivalents (METs) and 6METs were 105 and 130?step/min when analysing men and women together. There were slight differences on the cut-points between women and men if data were analysed separately. Conclusions In order to meet PA guidelines, Chinese young adult should walk 30?min with at least 105 step/min or 3150 steps or 2?km with the same step-rate per day. Walking at a higher speed of 130 step/min might provide additional health benefit. PMID:23335555

Wang, Huan; Zhang, Yan-feng; Xu, Liang-liang; Jiang, Chong-min

2013-01-01

300

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

PubMed Central

Background The Figure-of-8 Walk Test (F8W) involves straight and curved paths and was designed to represent walking skill in everyday life. Objective The purposes of this study were to validate the measure in older adults with walking difficulties and to explore correlates of the curved-path walking measure not represented by a straight-path walking measure. Design Fifty-one community-dwelling older adults with mobility disability participated in 2 baseline visits as part of an intervention study. Methods The F8W time, steps, and smoothness and measures of gait (gait speed, modified Gait Abnormality Rating Scale [GARS-M]), physical function (Late Life Function and Disabilities Index [LLFDI], Survey of Activities and Fear of Falling in the Elderly [SAFFE], Gait Efficacy Scale [GES], Physical Performance Test [PPT], and fall history), and movement control and planning (gait variability, Trail Making Test B [Trails B]) were recorded in each test session. Bivariate correlations for the F8W with each variable were conducted to examine concurrent and construct validity. Adjusted linear regression analyses were performed to explore the variance in mobility explained by F8W independent of gait speed. Results Figure-of-8 Walk Test time correlated with gait (gait speed, r=?.570; GARS-M, r=.281), physical function (LLFDI function, r=?.469; SAFFE restriction subscale, r=.370; PPT, r=?.353), confidence in walking (GES, r=?.468), and movement control (step length coefficient of variation, r=.279; step width coefficient of variation, r=?.277; Trails B, r=.351). Figure-of-8 Walk Test steps correlated with step width variability (r=?.339) and was related to fear of falling (t=?2.50). All correlations were significant (P<.05). Limitations This pilot study had a small sample size, and further research is needed. Conclusions The F8W is a valid measure of walking skill among older adults with mobility disability and may provide information complementary to gait speed. PMID:19959654

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

2010-01-01

301

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

Microsoft Academic Search

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

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

2007-01-01

302

Kinematic parameters of sheep walking on a treadmill.  

PubMed

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

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

2014-12-01

303

Record statistics of financial time series and geometric random walks  

NASA Astrophysics Data System (ADS)

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

Sabir, Behlool; Santhanam, M. S.

2014-09-01

304

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 ...

305

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.

306

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 ...

307

A walking tour of the Calaveras fault in Hollister, California  

NSDL National Science Digital Library

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

Dellinger, Joe

308

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

309

Walking and searching in time-varying networks  

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

310

Random Walks and Search in Time-Varying Networks  

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

311

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.

312

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

313

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...

314

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

315

Record statistics of financial time series and geometric random walks.  

PubMed

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

Sabir, Behlool; Santhanam, M S

2014-09-01

316

Is a practice incremental shuttle walk test really necessary?  

PubMed

The incremental and endurance shuttle walking tests (ISWT and ESWT) are measures of exercise tolerance commonly used in pulmonary rehabilitation (PR). A practice ISWT is advocated but often omitted by PR centres. We aimed to investigate the effect of such an omission within a clinical PR service. Between October 2002 and October 2008, 392 patients attending PR completed a practice ISWT and an ISWT. Results showed that patients walked significantly further on ISWT compared to practice ISWT (p ? 0.001). A significant difference in ESWT level was found between those calculated from practice ISWT and those calculated from ISWT (p ? .001). Despite a visual trend towards a negative relationship between distance walked at baseline (practice ISWT) and magnitude of the difference between the two walks, this did not meet statistical significance (p = 0.409). Absence of a practice ISWT could lead to possible clinical misjudgements. PMID:21799084

Dyer, Fran; Marriner, Pamela; Cheema, Katherine; Bott, Julia

2011-01-01

317

Easy-to-Walk Communities Linked to Sharper Senior Minds  

MedlinePLUS

... professor of clinical psychology at the University of Kansas in Lawrence. "People can walk either to get ... in a peer-reviewed journal. SOURCE: University of Kansas, news release, Nov. 7, 2014 HealthDay Copyright (c) ...

318

Finding structural anomalies in graphs by means of quantum walks  

SciTech Connect

We explore the possibility of using quantum walks on graphs to find structural anomalies, such as extra edges or loops, on a graph. We focus our attention on star graphs, whose edges are like spokes coming out of a central hub. If there are N spokes, we show that a quantum walk can find an extra edge connecting two of the spokes or a spoke with a loop on it in O({radical}(N)) steps. We initially find that if all except one of the spokes have loops, the walk will not find the spoke without a loop, but this can be fixed if we choose the phase with which the particle is reflected from the vertex without the loop. Consequently, quantum walks can, under some circumstances, be used to find structural anomalies in graphs.

Feldman, Edgar [Department of Mathematics, Graduate Center of the City University of New York, 365 Fifth Avenue, New York, New York 10016 (United States); Hillery, Mark; Zheng, Hongjun [Department of Physics, Hunter College of the City University of New York, 695 Park Avenue, New York, New York 10021 (United States); Lee, Hai-Woong [Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon 305-701 (Korea, Republic of); Reitzner, Daniel; Buzek, Vladimir [Research Center for Quantum Information, Slovak Academy of Sciences, Dubravska cesta 9, 845 11 Bratislava (Slovakia)

2010-10-15

319

Typical Framing of Bridge Ends and New Walk on Upstream ...  

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

Typical Framing of Bridge Ends and New Walk on Upstream Side, Typical Sway Bracing Above Upper Stringers, Typical Sway Bracing Below Floor Beams - Covered Bridge, Spanning Connecticut River, Orford, Grafton County, NH

320

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

321

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

322

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

323

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

324

Dirac equation with an ultraviolet cutoff and a quantum walk  

Microsoft Academic Search

The weak convergence theorems of the one- and two-dimensional simple quantum walks, SQW(d),d=1,2, show a striking contrast to the classical counterparts, the simple random walks, SRW(d). In the SRW(d), the distribution of position X(t) of the particle starting from the origin converges to the Gaussian distribution in the diffusion scaling limit, in which the time scale T and spatial scale

Fumihito Satoand; Makoto Katori

2010-01-01

325

Dirac equation with an ultraviolet cutoff and a quantum walk  

Microsoft Academic Search

The weak convergence theorems of the one- and two-dimensional simple quantum walks, SQW{sup (d)},d=1,2, show a striking contrast to the classical counterparts, the simple random walks, SRW{sup (d)}. In the SRW{sup (d)}, the distribution of position X(t) of the particle starting from the origin converges to the Gaussian distribution in the diffusion scaling limit, in which the time scale T

Fumihito Sato; Makoto Katori

2010-01-01

326

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

327

Ising model observables and non-backtracking walks  

NASA Astrophysics Data System (ADS)

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

2014-08-01

328

Velocity-Based Stability Margins for Fast Bipedal Walking  

Microsoft Academic Search

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

Jerry E. Pratt; Russ Tedrake

329

A Conditional Local Limit Theorem for Recurrent Random Walk  

Microsoft Academic Search

Let $S_n, n = 1, 2, 3, \\\\cdots$ denote the recurrent random walk formed by the partial sums of i.i.d. lattice random variables with mean zero and finite variance. Let $T_{\\\\{x\\\\}} = \\\\min \\\\lbrack n \\\\geqq 1 \\\\mid S_n = x \\\\rbrack$ with $T \\\\equiv T_{\\\\{0\\\\}}$. We obtain a local limit theorem for the random walk conditioned by the event

W. D. Kaigh

1975-01-01

330

Walking Pattern Analysis of Humanoid Robot Using Support Vector Regression  

Microsoft Academic Search

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

Dongwon Kim; Gwi-tae Park

2006-01-01

331

Control of Biped Walking Robot with IPMC Linear Actuator  

Microsoft Academic Search

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

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

2005-01-01

332

Vertical reaction forces and kinematics of backward walking underwater  

Microsoft Academic Search

The aim of this study was to compare the first and second peaks of the vertical ground reaction force (VGRF) and kinematics at initial contact (IC) and final stance (FS) during walking in one of two directions (forward×backward) and two environments (on land×underwater). Twenty-two adults (24.6±2.6 years) walking forward (FW) and backward (BW) on a 7.5m walkway with a central

Leticia Calado Carneiro; Stella Maris Michaelsen; Helio Roesler; Alessandro Haupenthal; Marcel Hubert; Eddy Mallmann

333

The effect of daily walking on body fat distribution  

Microsoft Academic Search

The effect of daily walking on body fat distribution was investigated using an electronic pedometer and ultrasonography. Subjects\\u000a were 77 women, aged 31 to 72 years. They were divided into four groups according to the average number of steps they walked\\u000a per day (I<7,500, 7,500 ?II<10,000, 10,000

Taeko Kajioka; Hiroshi Shimokata; Yuzo Sato

2000-01-01

334

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

335

Dog ownership, dog walking, and children's and parents' physical activity.  

PubMed

This study aimed to determine cross-sectional associations of dog ownership, dog walking, and physical activity (PA) among children and their parents. Objective measures of PA were obtained for children ages 5-6 and 10-12 years from 19 primary schools across Melbourne, Australia. Parents self-reported their PA, dog ownership, and frequency of dog walking: 53% of families owned a dog, 41% of children who owned a dog did not walk their dog at all, and 32% reported never or rarely walking their dog as a family. Dog ownership was associated with an additional 29 min/day in PA among younger girls, and 70 and 59 min/week more in PA among mothers of younger boys and older girls, respectively. Among mothers of older girls, dog owners were 1.6 times as likely to meet PA guidelines. Mothers with older boys and girls, and fathers with younger boys, who reported walking the dog regularly as a family, spent more time in PA (105, 90, and 158 more min/week, respectively). Promoting dog ownership and dog walking among children and as a family are potential strategies for increasing PA participation in some families. PMID:20949846

Salmon, Jo; Timperio, Anna; Chu, Binh; Veitch, Jenny

2010-09-01

336

The Fixed Irreducible Bridge Ensemble for Self-Avoiding Walks  

NASA Astrophysics Data System (ADS)

We define a new ensemble for self-avoiding walks in the upper half-plane, the fixed irredicible bridge ensemble, by considering self-avoiding walks in the upper half-plane up to their $n$-th bridge height, $Y_n$, and scaling the walk by $1/Y_n$ to obtain a curve in the unit strip, and then taking $n\\to\\infty$. We then conjecture a relationship between this ensemble to $\\SLE$ in the unit strip from $0$ to a fixed point along the upper boundary of the strip, integrated over the conjectured exit density of self-avoiding walk spanning a strip in the scaling limit. We conjecture that there exists a positive constant $\\sigma$ such that $n^{-\\sigma}Y_n$ converges in distribution to that of a stable random variable as $n\\to\\infty$. Then the conjectured relationship between the fixed irreducible bridge scaling limit and $\\SLE$ can be described as follows: If one takes a SAW considered up to $Y_n$ and scales by $1/Y_n$ and then weights the walk by $Y_n$ to an appropriate power, then in the limit $n\\to\\infty$, one should obtain a curve from the scaling limit of the self-avoiding walk spanning the unit strip. In addition to a heuristic derivation, we provide numerical evidence to support the conjecture and give estimates for the boundary scaling exponent.

Gilbert, Michael James

2015-01-01

337

The fixed irreducible bridge ensemble for self-avoiding walks  

E-print Network

We define a new ensemble for self-avoiding walks in the upper half-plane, the fixed irredicible bridge ensemble, by considering self-avoiding walks in the upper half-plane up to their $n$-th bridge height, $Y_n$, and scaling the walk by $1/Y_n$ to obtain a curve in the unit strip, and then taking $n\\to\\infty$. We then conjecture a relationship between this ensemble to $\\SLE$ in the unit strip from $0$ to a fixed point along the upper boundary of the strip, integrated over the conjectured exit density of self-avoiding walk spanning a strip in the scaling limit. We conjecture that there exists a positive constant $\\sigma$ such that $n^{-\\sigma}Y_n$ converges in distribution to that of a stable random variable as $n\\to\\infty$. Then the conjectured relationship between the fixed irreducible bridge scaling limit and $\\SLE$ can be described as follows: If one takes a SAW considered up to $Y_n$ and scales by $1/Y_n$ and then weights the walk by $Y_n$ to an appropriate power, then in the limit $n\\to\\infty$, one should obtain a curve from the scaling limit of the self-avoiding walk spanning the unit strip. In addition to a heuristic derivation, we provide numerical evidence to support the conjecture and give estimates for the boundary scaling exponent.

Michael James Gilbert

2014-10-17

338

Early Changes in Muscle Activation Patterns of Toddlers During Walking  

PubMed Central

Early locomotor behavior has been the focus of considerable attention by developmentalists over several decades. Few studies have addressed explicitly patterns of muscle activity that underlie this coordination pattern. Our purposes were to illustrate a method to determine objectively the onset and offset of muscle firings during early walking and to investigate the emergence of patterns of activation of the core locomotor muscles. We tested eight toddlers as they walked overground at walking onset (max. of 3–6 independent steps) and after three months of walking experience. Surface electrodes monitored activity of the gastrocnemius, tibialis anterior, quadriceps, and hamstrings. We reduced EMG signals to a frame-by-frame designation of “on-off,” followed by muscle state and co-contraction analyses, and probability distributions for each muscle’s activity across multiple cycles. Our results clearly show that at walking onset muscle activity was highly variable with few, if any, muscles showing recurring patterns of behavior, within or among toddlers. Variability and co-activation decreased with walking experience but remained inconsistent, in contrast to the significant increase in stability shown for joint coordination and endpoint (foot placement) parameters. We propose this trend emerges because of the high number of options (muscle combinations) available. Toddlers learn first to marshal sufficient force to balance and make forward progress but slowly discover how to optimize these resources. PMID:17138273

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

2006-01-01

339

Introduction of New Motion Measurement Equipment into Virtual Walk System  

NASA Astrophysics Data System (ADS)

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

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

340

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

341

Predicting human walking gaits with a simple planar model.  

PubMed

Models of human walking with moderate complexity have the potential to accurately capture both joint kinematics and whole body energetics, thereby offering more simultaneous information than very simple models and less computational cost than very complex models. This work examines four- and six-link planar biped models with knees and rigid circular feet. The two differ in that the six-link model includes ankle joints. Stable periodic walking gaits are generated for both models using a hybrid zero dynamics-based control approach. To establish a baseline of how well the models can approximate normal human walking, gaits were optimized to match experimental human walking data, ranging in speed from very slow to very fast. The six-link model well matched the experimental step length, speed, and mean absolute power, while the four-link model did not, indicating that ankle work is a critical element in human walking models of this type. Beyond simply matching human data, the six-link model can be used in an optimization framework to predict normal human walking using a torque-squared objective function. The model well predicted experimental step length, joint motions, and mean absolute power over the full range of speeds. PMID:24565183

Martin, Anne E; Schmiedeler, James P

2014-04-11

342

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

PubMed Central

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

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

2011-01-01

343

Monitoring butterfly abundance: beyond Pollard walks.  

PubMed

Most butterfly monitoring protocols rely on counts along transects (Pollard walks) to generate species abundance indices and track population trends. It is still too often ignored that a population count results from two processes: the biological process (true abundance) and the statistical process (our ability to properly quantify abundance). Because individual detectability tends to vary in space (e.g., among sites) and time (e.g., among years), it remains unclear whether index counts truly reflect population sizes and trends. This study compares capture-mark-recapture (absolute abundance) and count-index (relative abundance) monitoring methods in three species (Maculinea nausithous and Iolana iolas: Lycaenidae; Minois dryas: Satyridae) in contrasted habitat types. We demonstrate that intraspecific variability in individual detectability under standard monitoring conditions is probably the rule rather than the exception, which questions the reliability of count-based indices to estimate and compare specific population abundance. Our results suggest that the accuracy of count-based methods depends heavily on the ecology and behavior of the target species, as well as on the type of habitat in which surveys take place. Monitoring programs designed to assess the abundance and trends in butterfly populations should incorporate a measure of detectability. We discuss the relative advantages and inconveniences of current monitoring methods and analytical approaches with respect to the characteristics of the species under scrutiny and resources availability. PMID:22859980

Pellet, Jérôme; Bried, Jason T; Parietti, David; Gander, Antoine; Heer, Patrick O; Cherix, Daniel; Arlettaz, Raphaël

2012-01-01

344

Walking capabilities of Gregor controlled through Walknet  

NASA Astrophysics Data System (ADS)

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

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

2007-05-01

345

Entangling power of disordered quantum walks  

NASA Astrophysics Data System (ADS)

We investigate how the introduction of different types of disorder affects the generation of entanglement between the internal (spin) and external (position) degrees of freedom in one-dimensional quantum random walks (QRWs). Disorder is modeled by adding another random feature to QRWs, i.e., the quantum coin that drives the system's evolution is randomly chosen at each position and/or at each time step, giving rise to dynamic, fluctuating, or static disorder. The first one is position independent, with every lattice site having the same coin at a given time; the second has time- and position-dependent randomness; and the third one is time independent. We show for several levels of disorder that dynamic disorder is the most powerful entanglement generator, followed closely by fluctuating disorder. Static disorder is the less efficient entangler, being almost always less efficient than the ordered case. Also, dynamic and fluctuating disorder lead to maximally entangled states asymptotically in time for any initial condition, while static disorder has no asymptotic limit and, similarly to the ordered case, has a long-time behavior highly sensitive to the initial conditions.

Vieira, Rafael; Amorim, Edgard P. M.; Rigolin, Gustavo

2014-04-01

346

Walking while talking: Investigation of alternate forms?  

PubMed Central

The aim of this study was to develop alternate forms of the walking while talking (WWT) dual task, and to determine whether beginning the WWT in mid-alphabet vs. at the beginning of the alphabet, affects task outcomes. Alternate test forms help reduce practice effects leading to more precise estimates of change over time. We conducted a cross-sectional study in 145 community-residing older adults (mean age, 79.2 ± 6.8 y) without dementia or depression. Subjects performed four WWT trials with a different initial letter (a, b, m or n). There were no differences in velocity, correct letters, or errors on WWT trials beginning at shared points in the alphabet (`a' compared to `b' and `m' compared to `n'). However, trials initiating with letters from the beginning of the alphabet compared to mid-alphabet showed significant differences (with higher number of correct letters and fewer errors for `a' and `b' trials) but not for velocity. Thus, starting WWT in mid-alphabet is different from starting at the beginning of the alphabet. Alternate forms of the WWT with two separate initial letters from a shared point of the alphabet (specifically `a' and `b' or `m' and `n') may be used upon repeated administration to reduce practice effects. PMID:21944476

Brandler, Tamar C.; Oh-Park, Mooyeon; Wang, Cuiling; Holtzer, Roee; Verghese, Joe

2012-01-01

347

Walking while talking: investigation of alternate forms.  

PubMed

The aim of this study was to develop alternate forms of the walking while talking (WWT) dual task, and to determine whether beginning the WWT in mid-alphabet vs. at the beginning of the alphabet, affects task outcomes. Alternate test forms help reduce practice effects leading to more precise estimates of change over time. We conducted a cross-sectional study in 145 community-residing older adults (mean age, 79.2 ± 6.8 y) without dementia or depression. Subjects performed four WWT trials with a different initial letter (a, b, m or n). There were no differences in velocity, correct letters, or errors on WWT trials beginning at shared points in the alphabet ('a' compared to 'b' and 'm' compared to 'n'). However, trials initiating with letters from the beginning of the alphabet compared to mid-alphabet showed significant differences (with higher number of correct letters and fewer errors for 'a' and 'b' trials) but not for velocity. Thus, starting WWT in mid-alphabet is different from starting at the beginning of the alphabet. Alternate forms of the WWT with two separate initial letters from a shared point of the alphabet (specifically 'a' and 'b' or 'm' and 'n') may be used upon repeated administration to reduce practice effects. PMID:21944476

Brandler, Tamar C; Oh-Park, Mooyeon; Wang, Cuiling; Holtzer, Roee; Verghese, Joe

2012-01-01

348

Holographic walking technicolor from D-branes  

NASA Astrophysics Data System (ADS)

We investigate a model of dynamical electroweak symmetry breaking via a dual gravitational description. The gravity dual is obtained by embedding a D7-D7¯ pair of branes into a type IIB background that is dual to a walking gauge theory. We develop further a previous study of this model. In particular, we show that there is a nontrivial relation that needs to be satisfied in order for axial-vector modes to exist. Furthermore, we compute explicitly the electroweak S parameter. The result is positive-definite and, as was to be expected, much smaller than in earlier QCD-like D-brane constructions. We also find the masses and decay constants of the vector and axial-vector mesons in this model. This allows us to obtain another estimate for S by summing the contributions of the discrete states. It is noteworthy that, in contrast to previous holographic studies, the sum of the first several lowest-lying states does give a very good approximation to the full answer.

Anguelova, Lilia; Suranyi, Peter; Wijewardhana, L. C. R.

2011-11-01

349

Reconstructing the behavior of walking fruit flies  

NASA Astrophysics Data System (ADS)

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

Berman, Gordon; Bialek, William; Shaevitz, Joshua

2010-03-01

350

Walking technipions in a holographic model  

NASA Astrophysics Data System (ADS)

We calculate masses of the technipions in the walking technicolor model with the anomalous dimension ?m=1 , based on a holographic model which has a naturally light technidilaton ? as a composite Higgs with mass m??125 GeV . The one-family model (with four weak doublets) is taken as a concrete example in such a framework, with the inputs being F?=v /2 ?123 GeV and m??125 GeV as well as ?m=1 . It is shown that technipion masses are enhanced by the large anomalous dimension to typically O (1 ) TeV . We find a correlation between the technipion masses and S(TC ) , the S parameter arising only from the technicolor sector. The current LHC data on the technipion mass limit thus constrains S(TC ) to be not as large as O (1 ), giving a direct constraint on the technicolor model building. This is a new constraint on the technicolor sector alone, quite independent of other sectors connected by the extended-technicolor-type interactions—in sharp contrast to the conventional S parameter constraint from the precision electroweak measurements.

Kurachi, Masafumi; Matsuzaki, Shinya; Yamawaki, Koichi

2014-11-01

351

Reliability of the walking energy cost test and the six-minute walk test in boys with Duchenne muscular dystrophy.  

PubMed

The walking energy cost test (WECT) is a useful tool when measuring ambulatory function in children with motor disorders. However, data on the reliability of this test in Duchenne muscular dystrophy (DMD) is not available. In this study we established the reliability of the WECT and the commonly used six-minute walk test (6MWT) in 19 boys with DMD, aged 6-12years. Participants performed the WECT and 6MWT twice within three weeks. Reliability was determined for walking distance (D, m) and gross energy cost (EC, Jkg(-1)m(-1)), using the intraclass correlation coefficient (ICC2,1) and smallest detectable change (SDC). Reliability for walking distance was good, with an ICC of 0.92 [95% CI: 0.81-0.97] and 0.83 [CI: 0.53-0.94] for the 6MWT and WECT, respectively, and an ICC of 0.85 [CI: 0.64-0.94] for gross EC. SDCs were 12.2% for D6MWT, 12.7% for DWECT and 18.5% for gross EC. In conclusion, in young boys with DMD, the reliability of both the WECT and 6MWT for assessing walking distance is adequate. Gross EC, as assessed with the WECT is also reliable and sufficiently sensitive to detect change in walking strain following interventions at group level. PMID:24365209

Kempen, J C E; Harlaar, J; van der Kooi, A J; de Groot, I J M; van den Bergen, J C; Niks, E H; Verschuuren, J J G M; Brehm, M A

2014-03-01

352

Walking Ability and Its Relationship to Self-Rated Health in Later Life  

PubMed Central

This study investigated the relationship between self-assessed overall health (SRH) and walking ability among older adults (n = 239) gauged using three well-established measures of walking ability (“normal” and “fast” walking speeds, and perceived walking difficulty). Logistic regression models adjusted for health, behavioral, and sociodemographic variables were used to estimate the relationship between the three measures of walking ability and SRH. Walking ability was significantly associated with SRH; notably, only normal walking speed discriminated between participants in all three SRH comparisons (good versus poor/bad, good versus fair, or excellent versus good). Health care providers, family, and friends should be attentive to reduced walking speed or complaints about difficulty walking because these are harbingers of health decline.

NEUFELD, STEWART; MACHACOVA, KATERINA; MOSSEY, JANA; LUBORSKY, MARK

2014-01-01

353

Recurrence properties of unbiased coined quantum walks on infinite d -dimensional lattices  

NASA Astrophysics Data System (ADS)

The Pólya number characterizes the recurrence of a random walk. We apply the generalization of this concept to quantum walks [M. Štefa?ák , Phys. Rev. Lett. 100, 020501 (2008)] which is based on a specific measurement scheme. The Pólya number of a quantum walk depends, in general, on the choice of the coin and the initial coin state, in contrast to classical random walks where the lattice dimension uniquely determines it. We analyze several examples to depict the variety of possible recurrence properties. First, we show that for the class of quantum walks driven by Hadamard tensor-product coins, the Pólya number is independent of the initial conditions and the actual coin operators, thus resembling the property of the classical walks. We provide an estimation of the Pólya number for this class of quantum walks. Second, we examine the two-dimensional Grover walk, which exhibits localization and thus is recurrent, except for a particular initial state for which the walk is transient. We generalize the Grover walk to show that one can construct in arbitrary dimensions a quantum walk which is recurrent. This is in great contrast with classical walks which are recurrent only for the dimensions d=1,2 . Finally, we analyze the recurrence of the 2D Fourier walk. This quantum walk is recurrent except for a two-dimensional subspace of the initial states. We provide an estimation of the Pólya number in its dependence on the initial state.

Štefa?ák, M.; Kiss, T.; Jex, I.

2008-09-01

354

Treadmill Training Improves Overground Walking Economy in Parkinson’s Disease: A Randomized, Controlled Pilot Study  

PubMed Central

Gait disturbances are one of the principal and most incapacitating symptoms of Parkinson’s disease (PD). In addition, walking economy is impaired in PD patients and could contribute to excess fatigue in this population. An important number of studies have shown that treadmill training can improve kinematic parameters in PD patients. However, the effects of treadmill and overground walking on the walking economy remain unknown. The goal of this study was to explore the walking economy changes in response to a treadmill and an overground training program, as well as the differences in the walking economy during treadmill and overground walking. Twenty-two mild PD patients were randomly assigned to a treadmill or overground training group. The training program consisted of 5?weeks (3 sessions/week). We evaluated the energy expenditure of overground walking, before and after each of the training programs. The energy expenditure of treadmill walking (before the program) was also evaluated. The treadmill, but not the overground training program, lead to an improvement in the walking economy (the rate of oxygen consumed per distance during overground walking at a preferred speed) in PD patients. In addition, walking on a treadmill required more energy expenditure compared with overground walking at the same speed. This study provides evidence that in mild PD patients, treadmill training is more beneficial compared with that of walking overground, leading to a greater improvement in the walking economy. This finding is of clinical importance for the therapeutic administration of exercise in PD. PMID:25309510

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

2014-01-01

355

Treadmill training improves overground walking economy in Parkinson's disease: a randomized, controlled pilot study.  

PubMed

Gait disturbances are one of the principal and most incapacitating symptoms of Parkinson's disease (PD). In addition, walking economy is impaired in PD patients and could contribute to excess fatigue in this population. An important number of studies have shown that treadmill training can improve kinematic parameters in PD patients. However, the effects of treadmill and overground walking on the walking economy remain unknown. The goal of this study was to explore the walking economy changes in response to a treadmill and an overground training program, as well as the differences in the walking economy during treadmill and overground walking. Twenty-two mild PD patients were randomly assigned to a treadmill or overground training group. The training program consisted of 5?weeks (3 sessions/week). We evaluated the energy expenditure of overground walking, before and after each of the training programs. The energy expenditure of treadmill walking (before the program) was also evaluated. The treadmill, but not the overground training program, lead to an improvement in the walking economy (the rate of oxygen consumed per distance during overground walking at a preferred speed) in PD patients. In addition, walking on a treadmill required more energy expenditure compared with overground walking at the same speed. This study provides evidence that in mild PD patients, treadmill training is more beneficial compared with that of walking overground, leading to a greater improvement in the walking economy. This finding is of clinical importance for the therapeutic administration of exercise in PD. PMID:25309510

Fernández-Del-Olmo, Miguel Angel; Sanchez, Jose Andres; Bello, Olalla; Lopez-Alonso, Virginia; Márquez, Gonzalo; Morenilla, Luis; Castro, Xabier; Giraldez, Manolo; Santos-García, Diego

2014-01-01

356

Dynamic instability during post-stroke hemiparetic walking.  

PubMed

Falls and fall-related injuries cause extremely costly and potentially fatal health problems in people post-stroke. However, there is no global indicator of walking instability for detecting which individuals will have increased risk of falls. The purposes of this study were to directly quantify walking stability in stroke survivors and neurologically intact controls and to determine which stability measures would reveal the changes in walking stability following stroke. This study thus provided an initial step to establish objective measures for identifying potential fallers. Nine post-stroke individuals and nine controls walked on a treadmill at four different speeds. We computed short-term local divergence exponent (LDE) and maximum Floquet multiplier (maxFM) of the trunk motion, average and variability of dynamic margins of stability (MOS) and step spatiotemporal measures. Post-stroke individuals demonstrated larger short-term LDE (p = 0.002) and maxFM (p = 0.041) in the mediolateral (ML) direction compared to the controls but remained orbitally stable (maxFM < 1). In addition, post-stroke individuals walked with greater average step width (p = 0.003) but similar average ML MOS (p = 0.154) compared to the controls. Post-stroke individuals also exhibited greater variability in all MOS and step measures (all p < 0.005). Our findings indicate that post-stroke individuals walked with greater local and orbital instability and gait variability than neurologically intact controls. The results suggest that short-term LDE of ML trunk motion and the variability of MOS and step spatiotemporal measures detect the changes in walking stability associated with stroke. These stability measures may have the potential for identifying those post-stroke individuals at increased risk of falls. PMID:24931112

Kao, Pei-Chun; Dingwell, Jonathan B; Higginson, Jill S; Binder-Macleod, Stuart

2014-07-01

357

Biomechanics and energetics of walking on uneven terrain  

PubMed Central

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

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

2013-01-01

358

Center of mass mechanics of chimpanzee bipedal walking.  

PubMed

Center of mass (CoM) oscillations were documented for 81 bipedal walking strides of three chimpanzees. Full-stride ground reaction forces were recorded as well as kinematic data to synchronize force to gait events and to determine speed. Despite being a bent-hip, bent-knee (BHBK) gait, chimpanzee walking uses pendulum-like motion with vertical oscillations of the CoM that are similar in pattern and relative magnitude to those of humans. Maximum height is achieved during single support and minimum height during double support. The mediolateral oscillations of the CoM are more pronounced relative to stature than in human walking when compared at the same Froude speed. Despite the pendular nature of chimpanzee bipedalism, energy recoveries from exchanges of kinetic and potential energies are low on average and highly variable. This variability is probably related to the poor phasic coordination of energy fluctuations in these facultatively bipedal animals. The work on the CoM per unit mass and distance (mechanical cost of transport) is higher than that in humans, but lower than that in bipedally walking monkeys and gibbons. The pronounced side sway is not passive, but constitutes 10% of the total work of lifting and accelerating the CoM. CoM oscillations of bipedally walking chimpanzees are distinctly different from those of BHBK gait of humans with a flat trajectory, but this is often described as "chimpanzee-like" walking. Human BHBK gait is a poor model for chimpanzee bipedal walking and offers limited insights for reconstructing early hominin gait evolution. Am J Phys Anthropol 156:422-433, 2015. © 2014 Wiley Periodicals, Inc. PMID:25407636

Demes, Brigitte; Thompson, Nathan E; O'Neill, Matthew C; Umberger, Brian R

2015-03-01

359

Increased walking variability in elderly persons with congestive heart failure  

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

360

A one-dimensional quantum walk with multiple-rotation on the coin  

E-print Network

We introduce and analyze a one-dimensional quantum walk with two time-independent rotations on the coin. We study the influence on the property of quantum walk due to the second rotation on the coin. Based on the asymptotic solution in the long time limit, a ballistic behaviour of this walk is observed. This quantum walk retains the quadratic growth of the variance if the combined operator of the coin rotations is unitary. That confirms no localization exhibits in this walk. This result can be extended to the walk with multiple time-independent rotations on the coin.

Peng Xue; Rong Zhang; Hao Qin; Xiang Zhan; Zhihao Bian; Jian Li

2014-04-06

361

Interactive cueing with walk-Mate for Hemiparetic Stroke Rehabilitation  

PubMed Central

Background Many techniques that compensate for locomotion problems in daily life using externally controlled stimulation have recently been reported. These techniques are beneficial for effortlessly supporting patients’ locomotive functions, but the users of such devices must necessarily remain dependent on them. It is possible that some individuals with gait impairment may be prevented recovering locomotive function. From a rehabilitation viewpoint, it may therefore be supposed that ideally, devices that can be used in daily life to improve the locomotive functions of the body itself should be proposed. Methods We evaluate the effectiveness of Walk-Mate, which has been used mainly as a gait compensation device, as a gait rehabilitation training device by analyzing improvement in locomotion before, during and after rehabilitation in hemiparetic patients and comparing it with a previous gait training method. Walk-Mate generates a model walking rhythm in response to a user’s locomotion in real time, and by indicating this rhythm using auditory stimuli, provides a technology that supports walking by reducing asymmetries and fluctuations in foot contact rhythm. If patients can use the system to learn a regulated walking rhythm, then it may also be expected to fulfil the functions of a gait rehabilitation training device for daily life. Results With regard to asymmetry, significantly improvements were seen for compensatory movement during training using Walk-Mate, but improvements were not retained as rehabilitative results. Regarding fluctuations in the foot contact period, significant improvement was observed for compensatory movement during training and these significant improvements were retained as rehabilitative results. In addition, it became clear that such improvement could not be adequately obtained by the previously proposed training technique utilizing constant rhythmic auditory stimulation. Conclusions Walk-Mate effectively compensated for locomotion problems of hemiparetic patients by improving gait rhythm both during and after training, suggesting that locomotive function can be effectively recovered in some patients. The interactive mechanism of Walk-Mate may be capable of simultaneously achieving the aims of gait compensation and gait rehabilitation training methods previously developed under individual frameworks. Walk-Mate is a promising technology for assisting the reintegration of disabled persons into society. PMID:22909032

2012-01-01

362

Walking vs running for hypertension, cholesterol, & diabetes risk reduction  

PubMed Central

Background To test whether equivalent energy expenditure by moderate-intensity (e.g., walking) and vigorous-intensity exercise (e.g., running) provides equivalent health benefits. Methods and Results We used the National Runners’ (n=33,060) and Walkers’ (n=15,945) Health Study cohorts to examine the effect of differences in exercise mode and thereby exercise intensity on coronary heart disease (CHD) risk factors. Baseline expenditure (METhr/d) was compared to self-reported, physician-diagnosed incident hypertension, hypercholesterolemia, diabetes and CHD during 6.2 years follow-up. Running significantly decreased the risks for incident hypertension by 4.2% (P<10-7), hypercholesterolemia by 4.3% (P<10-14), diabetes by 12.1% (P<10-5), and CHD by 4.5% per METh/d run (P=0.05). The corresponding reductions for walking were 7.2% (P<10-6), 7.0% (P<10-8), 12.3% (P<10-4), and 9.3% (P=0.01). Relative to <1.8 METh/d, the risk reductions for 1.8 to 3.6, 3.6 to 5.4, 5.4 to 7.2, and ? 7.2 METh/d were: 1) 10.1%, 17.7%, 25.1% and 34.9% from running and 14.0%, 23.8%, 21.8% and 38.3% from walking for hypercholesterolemia; 2) 19.7%, 19.4%, 26.8% and 39.8% from running and 14.7%, 19.1%, 23.6% and 13.3% from walking for hypertension; 3) 43.5%, 44.1%, 47.7% and 68.2% from running and 34.1%, 44.2%, and 23.6% from walking for diabetes (too few cases for diabetes for walking >5.4 METh/d). The risk reductions were not significantly greater for running than walking for diabetes (P=0.94) or CHD (P=0.26), and only marginally greater for walking than running for hypertension (P=0.06) and hypercholesterolemia (P=0.04). Conclusion Equivalent energy expenditures by moderate (walking) and vigorous (running) exercise produced similar risk reductions for hypertension, hypercholesterolemia, diabetes, and CHD, but there is limited statistical power to evaluate CHD conclusively. PMID:23559628

Thompson, Paul D.

2013-01-01

363

Search for Directed Networks by Different Random Walk Strategies  

NASA Astrophysics Data System (ADS)

A comparative study is carried out on the efficiency of five different random walk strategies searching on directed networks constructed based on several typical complex networks. Due to the difference in search efficiency of the strategies rooted in network clustering, the clustering coefficient in a random walker's eye on directed networks is defined and computed to be half of the corresponding undirected networks. The search processes are performed on the directed networks based on Erdös—Rényi model, Watts—Strogatz model, Barabási—Albert model and clustered scale-free network model. It is found that self-avoiding random walk strategy is the best search strategy for such directed networks. Compared to unrestricted random walk strategy, path-iteration-avoiding random walks can also make the search process much more efficient. However, no-triangle-loop and no-quadrangle-loop random walks do not improve the search efficiency as expected, which is different from those on undirected networks since the clustering coefficient of directed networks are smaller than that of undirected networks.

Zhu, Zi-Qi; Jin, Xiao-Ling; Huang, Zhi-Long

2012-03-01

364

Walk-off correction with AFB nonlinear composites  

NASA Astrophysics Data System (ADS)

Beam walk-off in uniaxial and biaxial crystals occurs when the phase normal of the propagating electromagnetic wave deviates from the direction of the Poynting vector. This beam walk-off limits frequency conversion efficiency and restricts the OPO tuning range. The beam walk-off angle in nonlinear single crystals can be alleviated by bonding similar non-linear crystals rotated by 180° with respect to each other. An even number of twisted twins of single crystals is formed that is stress-free and has negligible loss at the AFB® (Adhesive-Free Bond) interfaces. Since no adhesive is employed and the bonding force consists primarily of Van der Waals attractive forces, there is no adverse effect or absorption at the bond interface. The theory of walk-off angles as a function of orientation for uniaxial and biaxial crystals is derived. Correcting beam walk-off by producing an AFB® composite configuration results in more efficient frequency conversion and thereby allows the generation of higher power output of frequency converted radiation for a given input power. Beam correction is demonstrated experimentally for zinc germanium phosphide (ZGP) as representative of a uniaxial nonlinear crystal, and on biaxial KTP crystals. AFB® composites of ZGP with inactive ends of gallium phosphide have been produced in an effort to further improve damage resistance of a ZGP optical parametric oscillator for frequency conversion into the mid-IR range.

Lee, H.-C.; Meissner, H. E.

2007-04-01

365

Random walks of colloidal probes in viscoelastic materials  

NASA Astrophysics Data System (ADS)

To overcome limitations of using a single fixed time step in random walk simulations, such as those that rely on the classic Wiener approach, we have developed an algorithm for exploring random walks based on random temporal steps that are uniformly distributed in logarithmic time. This improvement enables us to generate random-walk trajectories of probe particles that span a highly extended dynamic range in time, thereby facilitating the exploration of probe motion in soft viscoelastic materials. By combining this faster approach with a Maxwell-Voigt model (MVM) of linear viscoelasticity, based on a slowly diffusing harmonically bound Brownian particle, we rapidly create trajectories of spherical probes in soft viscoelastic materials over more than 12 orders of magnitude in time. Appropriate windowing of these trajectories over different time intervals demonstrates that random walk for the MVM is neither self-similar nor self-affine, even if the viscoelastic material is isotropic. We extend this approach to spatially anisotropic viscoelastic materials, using binning to calculate the anisotropic mean square displacements and creep compliances along different orthogonal directions. The elimination of a fixed time step in simulations of random processes, including random walks, opens up interesting possibilities for modeling dynamics and response over a highly extended temporal dynamic range.

Khan, Manas; Mason, Thomas G.

2014-04-01

366

Effect of walking velocity on forelimb kinematics and kinetics.  

PubMed

A database of biomechanical variables obtained from normal horses walking at a range of velocities is needed for comparison with the variables obtained from lame horses in which velocity cannot be predetermined. The objective was to investigate velocity-dependent changes in selected kinematic variables, ground reaction forces (GRF) and net joint energies in the forelimb and to develop statistical equations to calculate expected values of these variables for horses walking at different velocities. Five sound horses walked at a range of velocities (0.82 to 1.91 m/s) over a force plate. Kinematic data were recorded simultaneously for 51 trials. Kinematic, GRF and energetic variables were determined using standard methods. Correlation and simple regression analyses between velocity and measured variables were performed. An increase in walking velocity was correlated with an increase in stride length and decreases in stride and stance duration. Vertical, braking and propulsive impulses decreased as a consequence of the large reduction in stance duration, even though peak vertical, braking and propulsive GRFs increased. There was no significant increase in energy generation at any of the forelimb joints, indicating that muscle activity was not the source of the increase in GRFs. Changes in the longitudinal GRFs appeared to be influenced by velocity-dependent increases in head and neck oscillations. The equations obtained in this study can be used to calculate the expected normal variables from a range of walking velocities and to detect deviations from normal values in lame horses. PMID:12405709

Khumsap, S; Clayton, H M; Lanovaz, J L; Bouchey, M

2002-09-01

367

Running for Exercise Mitigates Age-Related Deterioration of Walking Economy  

PubMed Central

Introduction Impaired walking performance is a key predictor of morbidity among older adults. A distinctive characteristic of impaired walking performance among older adults is a greater metabolic cost (worse economy) compared to young adults. However, older adults who consistently run have been shown to retain a similar running economy as young runners. Unfortunately, those running studies did not measure the metabolic cost of walking. Thus, it is unclear if running exercise can prevent the deterioration of walking economy. Purpose To determine if and how regular walking vs. running exercise affects the economy of locomotion in older adults. Methods 15 older adults (69±3 years) who walk ?30 min, 3x/week for exercise, “walkers” and 15 older adults (69±5 years) who run ?30 min, 3x/week, “runners” walked on a force-instrumented treadmill at three speeds (0.75, 1.25, and 1.75 m/s). We determined walking economy using expired gas analysis and walking mechanics via ground reaction forces during the last 2 minutes of each 5 minute trial. We compared walking economy between the two groups and to non-aerobically trained young and older adults from a prior study. Results Older runners had a 7–10% better walking economy than older walkers over the range of speeds tested (p?=?.016) and had walking economy similar to young sedentary adults over a similar range of speeds (p?=?.237). We found no substantial biomechanical differences between older walkers and runners. In contrast to older runners, older walkers had similar walking economy as older sedentary adults (p?=?.461) and ?26% worse walking economy than young adults (p<.0001). Conclusion Running mitigates the age-related deterioration of walking economy whereas walking for exercise appears to have minimal effect on the age-related deterioration in walking economy. PMID:25411850

Ortega, Justus D.; Beck, Owen N.; Roby, Jaclyn M.; Turney, Aria L.; Kram, Rodger

2014-01-01

368

Change in Action: How Infants Learn to Walk Down Slopes  

PubMed Central

A critical aspect of perception-action coupling is the ability to modify ongoing actions in accordance with variations in the environment. Infants’ ability to modify their gait patterns to walk down shallow and steep slopes was examined at three nested time scales. Across sessions, a microgenetic training design showed rapid improvements after the first session in infants receiving concentrated practice walking down slopes and in infants in a control group who were tested only at the beginning and end of the study. Within sessions, analyses across easy and challenging slope angles showed that infants used a “braking strategy” to curb increases in walking speed across increasingly steeper slopes. Within trials, comparisons of infants’ gait modifications before and after stepping over the brink of the slopes showed that the braking strategy was planned prospectively. Findings illustrate how observing change in action provides important insights into the process of skill acquisition. PMID:19840044

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

2009-01-01

369

Wilson loops in string duals of walking and flavored systems  

SciTech Connect

We consider the vacuum expectation value of Wilson loop operators by studying the behavior of string probes in solutions of type-IIB string theory generated by N{sub c} D5-branes wrapped on an S{sup 2} internal manifold. In particular, we focus on solutions to the background equations that are dual to field theories with a walking gauge coupling as well as for flavored systems. We present in detail our walking solution and emphasize various general aspects of the procedure to study Wilson loops using string duals. We discuss the special features that the strings show when probing the region associated with the walking of the field-theory coupling.

Nunez, Carlos; Piai, Maurizio; Rago, Antonio [Swansea University, School of Physical Sciences, Singleton Park, Swansea, Wales (United Kingdom)

2010-04-15

370

Convergence of a random walk method for the Burgers equation  

SciTech Connect

In this paper we consider a random walk algorithm for the solution of Burgers' equation. The algorithm uses the method of fractional steps. The non-linear advection term of the equation is solved by advecting ''fluid'' particles in a velocity field induced by the particles. The diffusion term of the equation is approximated by adding an appropriate random perturbation to the positions of the particles. Though the algorithm is inefficient as a method for solving Burgers' equation, it does model a similar method, the random vortex method, which has been used extensively to solve the incompressible Navier-Stokes equations. The purpose of this paper is to demonstrate the strong convergence of our random walk method and so provide a model for the proof of convergence for more complex random walk algorithms; for instance, the random vortex method without boundaries.

Roberts, S.

1985-10-01

371

Structural characterization of ice polymorphs from self-avoiding walks  

NASA Astrophysics Data System (ADS)

Topological properties of crystalline ice structures are studied by means of self-avoiding walks on their H-bond networks. The number of self-avoiding walks, Cn, for eight ice polymorphs has been obtained by direct enumeration up to walk length n=27. This has allowed us to determine the ‘connective constant' or effective coordination number ? of these structures as the limit of the ratio Cn/Cn-1 for large n. This structure-dependent parameter ? is related with other topological characteristics of ice polymorphs, such as the mean and minimum ring size, or the topological density of network sites. A correlation between the connective constant and the configurational entropy of hydrogen-disordered ice structures is discussed.

Herrero, Carlos P.

2014-08-01

372

Gait event detection during stair walking using a rate gyroscope.  

PubMed

Gyroscopes have been proposed as sensors for ambulatory gait analysis and functional electrical stimulation systems. These applications often require detection of the initial contact (IC) of the foot with the floor and/or final contact or foot off (FO) from the floor during outdoor walking. Previous investigations have reported the use of a single gyroscope placed on the shank for detection of IC and FO on level ground and incline walking. This paper describes the evaluation of a gyroscope placed on the shank for determination of IC and FO in subjects ascending and descending a set of stairs. Performance was compared with a reference pressure measurement system. The absolute mean difference between the gyroscope and the reference was less than 45 ms for IC and better than 135 ms for FO for both activities. Detection success was over 93%. These results provide preliminary evidence supporting the use of a gyroscope for gait event detection when walking up and down stairs. PMID:24651724

Formento, Paola Catalfamo; Acevedo, Ruben; Ghoussayni, Salim; Ewins, David

2014-01-01

373

Asymptotic Dynamics of Coined Quantum Walks on Percolation Graphs  

NASA Astrophysics Data System (ADS)

Quantum walks obey unitary dynamics: they form closed quantum systems. The system becomes open if the walk suffers from imperfections represented as missing links on the underlying basic graph structure, described by dynamical percolation. Openness of the system’s dynamics creates decoherence, leading to strong mixing. We present a method to analytically solve the asymptotic dynamics of coined, percolated quantum walks for a general graph structure. For the case of a circle and a linear graph we derive the explicit form of the asymptotic states. We find that a rich variety of asymptotic evolutions occur: not only the fully mixed state, but other stationary states; stable periodic and quasiperiodic oscillations can emerge, depending on the coin operator, the initial state, and the topology of the underlying graph.

Kollár, B.; Kiss, T.; Novotný, J.; Jex, I.

2012-06-01

374

Optical variability of quasars: a damped random walk  

NASA Astrophysics Data System (ADS)

A damped random walk is a stochastic process, defined by an exponential covariance matrix that behaves as a random walk for short time scales and asymptotically achieves a finite variability amplitude at long time scales. Over the last few years, it has been demonstrated, mostly but not exclusively using SDSS data, that a damped random walk model provides a satisfactory statistical description of observed quasar variability in the optical wavelength range, for rest-frame timescales from 5 days to 2000 days. The best-fit characteristic timescale and asymptotic variability amplitude scale with the luminosity, black hole mass, and rest wavelength, and appear independent of redshift. In addition to providing insights into the physics of quasar variability, the best-fit model parameters can be used to efficiently separate quasars from stars in imaging surveys with adequate long-term multi-epoch data, such as expected from LSST.

Ivezi?, Željko; MacLeod, Chelsea

2014-07-01

375

Shape anisotropy of a single random-walk polymer  

PubMed Central

Random walks have been used to describe a wide variety of systems ranging from cell colonies to polymers. Sixty-five years ago, Kuhn [Kuhn, W. (1934) Kolloid-Z. 68, 2–11] made the prediction, backed later by computer simulations, that the overall shape of a random-walk polymer is aspherical, yet no experimental work has directly tested Kuhn's general idea and subsequent computer simulations. By using fluorescence microscopy, we monitored the conformation of individual, long, random-walk polymers (fluorescently labeled DNA molecules) at equilibrium. We found that a polymer most frequently adopts highly extended, nonfractal structures with a strongly anisotropic shape. The ensemble-average ratio of the lengths of the long and short axes of the best-fit ellipse of the polymer was much larger than unity. PMID:10984514

Haber, Charbel; Ruiz, Sami Alom; Wirtz, Denis

2000-01-01

376

Winning quick and dirty: the greedy random walk  

NASA Astrophysics Data System (ADS)

As a strategy to complete games quickly, we investigate one-dimensional random walks where the step length increases deterministically upon each return to the origin. When the step length after the kth return equals k, the displacement of the walk x grows linearly in time. Asymptotically, the probability distribution of displacements is a purely exponentially decaying function of |x|/t. The probability E(t, L) for the walk to escape a bounded domain of size L at time t decays algebraically in the long-time limit, E(t, L) ~ L/t2. Consequently, the mean escape time langtrang ~ Lln L, while langtnrang ~ L2n-1 for n > 1. Corresponding results are derived when the step length after the kth return scales as k? for ? > 0.

Ben-Naim, E.; Redner, S.

2004-11-01

377

Scaling random walks on arbitrary sets  

NASA Astrophysics Data System (ADS)

Let I be a countably infinite set of points in [open face R] which we can write as I={ui: i[set membership][open face Z]}, with uiwalk, when repeatedly rescaled suitably in space and time, looks more and more like a Brownian motion. In this paper we explore the convergence properties of the Markov chain Y on the set I under suitable space-time scalings. Later, we consider some cases when the set I consists of the points of a renewal process and the jump rates assigned to each state in I are perhaps also randomly chosen.This work sprang from a question asked by one of us (Sibson) about ‘driftless nearest-neighbour’ Markov chains on countable subsets I of [open face R]d, work of Sibson [7] and of Christ, Friedberg and Lee [2] having identified examples of such chains in terms of the Dirichlet tessellation associated with I. Amongst methods which can be brought to bear on this d-dimensional problem is the theory of Dirichlet forms. There are potential problems in doing this because we wish I to be random (for example, a realization of a Poisson point process), we do not wish to impose artificial boundedness conditions which would clearly make things work for certain deterministic sets I. In the 1-dimensional case discussed here and in the following paper by Harris, much simpler techniques (where we embed the Markov chain in a Brownian motion using local time) work very effectively; and it is these, rather than the theory of Dirichlet forms, that we use.

Harris, Simon C.; Williams, David; Sibson, Robin

1999-01-01

378

Walking with wider steps increases stance phase gluteus medius activity.  

PubMed

Increases in step width have been reported for several clinical populations, including older adults and stroke survivors. These populations often also exhibit decreased hip abductor strength, suggesting that walking with wider steps may be an adaptive response in order to reduce the mechanical demands on the hip abductors. The purpose of this study was to quantify the relationship between step width and gluteus medius (GM) activity during walking. Fourteen young, uninjured adults walked on a treadmill at 1.25m/s for four step width conditions (Normal, Narrow, Medium, and Wide) while step width and stance phase GM electromyographic (EMG) activity were quantified. We also measured hip abduction torque and GM activity during maximum voluntary isometric contractions (MVICs) at three hip angles (neutral, abducted 10°, and abducted 20°). During walking trials, GM activity was significantly (p<0.0001) influenced by step width; compared to Normal walking, GM activity was 47% higher with Wide steps and 24% lower with Narrow steps. We also observed a weak positive correlation (r=0.18±0.14) between step width and GM activity during Normal walking, as GM activity was higher with wider steps. These results cannot be attributed to changes in GM conformation under the recording electrode, as GM activity was not influenced by hip angle during MVICs. The increased GM activity with wider steps does not support the proposal that increasing step width would be a beneficial adaptation to weakened hip abductors. A likely alternative explanation is that increased step width is a response to decreased gait balance. PMID:25300241

Kubinski, Samantha N; McQueen, Christina A; Sittloh, Keir A; Dean, Jesse C

2015-01-01

379

Drops walking on a vibrating bath: towards a hydrodynamic pilot-wave theory  

E-print Network

We present the results of a combined experimental and theoretical investigation of droplets walking on a vertically vibrating fluid bath. Several walking states are reported, including pure resonant walkers that bounce ...

Bush, John W. M.

380

Modeling and analysis of passive dynamic bipedal walking with segmented feet and compliant joints  

NASA Astrophysics Data System (ADS)

Passive dynamic walking has been developed as a possible explanation for the efficiency of the human gait. This paper presents a passive dynamic walking model with segmented feet, which makes the bipedal walking gait more close to natural human-like gait. The proposed model extends the simplest walking model with the addition of flat feet and torsional spring based compliance on ankle joints and toe joints, to achieve stable walking on a slope driven by gravity. The push-off phase includes foot rotations around the toe joint and around the toe tip, which shows a great resemblance to human normal walking. This paper investigates the effects of the segmented foot structure on bipedal walking in simulations. The model achieves satisfactory walking results on even or uneven slopes.

Huang, Yan; Wang, Qi-Ning; Gao, Yue; Xie, Guang-Ming

2012-10-01

381

A knee brace design to reduce the energy consumption of walking  

E-print Network

Recent research into the mechanics of walking indicates that a quasi passive wearable device could be created which dramatically reduces the metabolic energy used in walking especially when the wearer is carrying additional ...

Carvey, Matthew R

2005-01-01

382

First passage time densities for random walk spans  

NASA Astrophysics Data System (ADS)

A general expression is derived for the Laplace transform of the probability density of the first passage time for the span of a symmetric continuous-time random walk to reach level S. We show that when the mean time between steps is finite, the mean first passage time to S is proportional to S 2. When the pausing time density is asymptotic to a stable density we show that the first passage density is also asymptotically stable. Finally when the jump distribution of the random walk has the asymptotic form p(j)˜A/|j| ?+1, 0 < ? < 2 it is shown that the mean first passage time to S goes like S ?.

Weiss, George H.; Dimarzio, Edmund A.; Gaylord, Richard J.

1986-02-01

383

Two-dimensional random walk in a bounded domain  

E-print Network

In a recent Letter Ciftci and Cakmak [EPL 87, 60003 (2009)] showed that the two dimensional random walk in a bounded domain, where walkers which cross the boundary return to a base curve near origin with deterministic rules, can produce regular patterns. Our numerical calculations suggest that the cumulative probability distribution function of the returning walkers along the base curve is a Devil's staircase, which can be explained from the mapping of these walks to a non-linear stochastic map. The non-trivial probability distribution function(PDF) is a universal feature of CCRW characterized by the fractal dimension d=1.75(0) of the PDF bounding curve.

Basu, Mahashweta

2010-01-01

384

Two-dimensional random walk in a bounded domain  

E-print Network

In a recent Letter Ciftci and Cakmak [EPL 87, 60003 (2009)] showed that the two dimensional random walk in a bounded domain, where walkers which cross the boundary return to a base curve near origin with deterministic rules, can produce regular patterns. Our numerical calculations suggest that the cumulative probability distribution function of the returning walkers along the base curve is a Devil's staircase, which can be explained from the mapping of these walks to a non-linear stochastic map. The non-trivial probability distribution function(PDF) is a universal feature of CCRW characterized by the fractal dimension d=1.75(0) of the PDF bounding curve.

Mahashweta Basu; P. K. Mohanty

2010-03-09

385

Massless Dirac Equation from Fibonacci Discrete-Time Quantum Walk  

E-print Network

Discrete-time quantum walks can be regarded as quantum dynamical simulators since they can simulate spatially discretized Schr\\"{o}dinger, massive Dirac, and Klein-Gordon equations. Here, two different types of Fibonacci discrete-time quantum walks are studied analytically. The first is the Fibonacci coin sequence with a generalized Hadamard coin and demonstrates six-step periodic dynamics. The other model is assumed to have three- or six-step periodic dynamics with the Fibonacci sequence. We analytically show that these models have ballistic transportation properties and continuous limits identical to those of the massless Dirac equation with coin basis change.

Giuseppe Di Molfetta; Lauchlan Honter; Ben B. Luo; Tatsuaki Wada; Yutaka Shikano

2014-10-17

386

Uniform mixing time for Random Walk on Lamplighter Graphs  

E-print Network

Suppose that $\\CG$ is a finite, connected graph and $X$ is a lazy random walk on $\\CG$. The lamplighter chain $X^\\diamond$ associated with $X$ is the random walk on the wreath product $\\CG^\\diamond = \\Z_2 \\wr \\CG$, the graph whose vertices consist of pairs $(f,x)$ where $f$ is a labeling of the vertices of $\\CG$ by elements of $\\Z_2$ and $x$ is a vertex in $\\CG$. There is an edge between $(f,x)$ and $(g,y)$ in $\\CG^\\diamond$ if and only if $x$ is adjacent to $y$ in $\\CG$ and $f(z) = g(z)$ for all $z \

Komjáthy, Júlia; Peres, Yuval

2011-01-01

387

Near-Hagedorn thermodynamics and random walks — extensions and examples  

NASA Astrophysics Data System (ADS)

In this paper, we discuss several explicit examples of the results obtained in [1]. We elaborate on the random walk picture in these spacetimes and how it is modified. Firstly we discuss the linear dilaton background. Then we analyze a previously studied toroidally compactified background where we determine the Hagedorn temperature and study the random walk picture. We continue with flat space orbifold models where we discuss boundary conditions for the thermal scalar. Finally, we study the general link between the quantum numbers in the fundamental domain and the strip and their role in thermodynamics.

Mertens, Thomas G.; Verschelde, Henri; Zakharov, Valentin I.

2014-11-01

388

Non-Gaussian propagator for elephant random walks  

NASA Astrophysics Data System (ADS)

For almost a decade the consensus has held that the random walk propagator for the elephant random walk (ERW) model is a Gaussian. Here we present strong numerical evidence that the propagator is, in general, non-Gaussian and, in fact, non-Lévy. Motivated by this surprising finding, we seek a second, non-Gaussian solution to the associated Fokker-Planck equation. We prove mathematically, by calculating the skewness, that the ERW Fokker-Planck equation has a non-Gaussian propagator for the superdiffusive regime. Finally, we discuss some unusual aspects of the propagator in the context of higher order terms needed in the Fokker-Planck equation.

da Silva, M. A. A.; Cressoni, J. C.; Schütz, Gunter M.; Viswanathan, G. M.; Trimper, Steffen

2013-08-01

389

Non-Gaussian propagator for elephant random walks.  

PubMed

For almost a decade the consensus has held that the random walk propagator for the elephant random walk (ERW) model is a Gaussian. Here we present strong numerical evidence that the propagator is, in general, non-Gaussian and, in fact, non-Lévy. Motivated by this surprising finding, we seek a second, non-Gaussian solution to the associated Fokker-Planck equation. We prove mathematically, by calculating the skewness, that the ERW Fokker-Planck equation has a non-Gaussian propagator for the superdiffusive regime. Finally, we discuss some unusual aspects of the propagator in the context of higher order terms needed in the Fokker-Planck equation. PMID:24032783

da Silva, M A A; Cressoni, J C; Schütz, Gunter M; Viswanathan, G M; Trimper, Steffen

2013-08-01

390

Quadriceps oxygenation changes during walking and running on a treadmill  

NASA Astrophysics Data System (ADS)

Vastus lateralis muscle oxygenation was investigated on volunteers as well as muscular dystrophy patients during a walking test, and on volunteers during a free running by a continuous wave near infrared instrument. The data were analyzed using an oxygenation index independent on pathlength changes. Walking did not significantly affect the oxygenation of volunteers and patients. A relative deoxygenation was found only during free running indicating an unbalance between oxygen supply and tissue oxygen extraction. Preliminary measurements of exercising muscle oxygen saturation were performed by a 110 MHz frequency-domain, multisource instrument.

Quaresima, Valentina; Pizzi, Assunta; De Blasi, Roberto A.; Ferrari, Adriano; de Angelis, Marco; Ferrari, Marco

1995-04-01

391

Kinematic variability and local dynamic stability of upper body motions when walking at different speeds  

Microsoft Academic Search

Abstract A ubiquitous,characteristic of elderly and,patients with gait disabilities is that they walk,slower than healthy controls. Many clinicians assume these patients walk slower to improve their stability, just as healthy people slow down when walking across ice. However, walking slower also leads to greater variability, which is often assumed to imply deteriorated stability. If this were true, then slowing down,would,be

Jonathan B. Dingwell; Laura C. Marin

392

Glucose Control and Walking in a Multiethnic Sample of Older Adults  

Microsoft Academic Search

Background: Although walking is the most commonly reported physical activity by older adults, there is a paucity of data determining the relationship between objectively determined walking behavior and glucose dynamics in older adults. Objective: This study was designed to investigate the relationship between objectively determined walking behavior and glucose control in a multiethnic sample of older adults. Methods: Data were

Ann M. Swartz; Scott J. Strath; Nora E. Miller; Susan E. Cashin; Linda J. Cieslik

2007-01-01

393

Women Who Take Walks: A Cultural Approach to Teaching Nineteenth-Century British Fiction.  

ERIC Educational Resources Information Center

Suggests that teachers can introduce the cultural context of nineteenth-century British fiction by exploring four types of walks that women characters take: the mission of mercy; the passionate, secret journey; the problem-solving walk; and the defiant or self-assertive walk of independence. (MS)

Connors, Patricia E.

1988-01-01

394

Symmetry-noise interplay in a quantum walk on an n -cycle  

Microsoft Academic Search

Augmenting the unitary transformation which generates a quantum walk by a generalized phase gate G is a symmetry for both noisy and noiseless quantum walk on a line, in the sense that it leaves the position probability distribution invariant. However, this symmetry breaks down in the case of a quantum walk on an n cycle, and hence can be regarded

Subhashish Banerjee; R. Srikanth; C. M. Chandrashekar; Pranaw Rungta

2008-01-01

395

Energetic Consequences of Walking Like an Inverted Pendulum: Step-to-Step Transitions  

E-print Network

ARTICLE Energetic Consequences of Walking Like an Inverted Pendulum: Step-to-Step Transitions, A.D, J.M. DONELAN, and A. RUINA. Energetic consequences of walking like an inverted pendulum: Step of step length, step frequency, and even step width that is energetically optimal (2,5,11). Walking

396

New Variance Ratio Tests to Identify Random Walk from the General Mean Reversion Model  

E-print Network

model on stock prices or other financial data. Some accept the random walk hypothesis but some reject it test, random walk, stock price, stock return. Kin Lam Department of Finance & Decision Sciences Hong. Random walks, a special case of unit root processes, help identify the kinds of shocks that drive stock

Chaudhuri, Sanjay

397

36 CFR 13.1312 - Climbing and walking on Exit Glacier.  

Code of Federal Regulations, 2010 CFR

... false Climbing and walking on Exit Glacier. 13.1312 Section 13.1312 Parks...1312 Climbing and walking on Exit Glacier. Except for areas designated by the...climbing or walking on, in, or under Exit Glacier is prohibited within 1/2 mile...

2010-07-01

398

36 CFR 13.1312 - Climbing and walking on Exit Glacier.  

Code of Federal Regulations, 2014 CFR

... false Climbing and walking on Exit Glacier. 13.1312 Section 13.1312 Parks...1312 Climbing and walking on Exit Glacier. Except for areas designated by the...climbing or walking on, in, or under Exit Glacier is prohibited within 1/2 mile...

2014-07-01

399

36 CFR 13.1312 - Climbing and walking on Exit Glacier.  

Code of Federal Regulations, 2011 CFR

... false Climbing and walking on Exit Glacier. 13.1312 Section 13.1312 Parks...1312 Climbing and walking on Exit Glacier. Except for areas designated by the...climbing or walking on, in, or under Exit Glacier is prohibited within 1/2 mile...

2011-07-01

400

36 CFR 13.1312 - Climbing and walking on Exit Glacier.  

Code of Federal Regulations, 2013 CFR

... false Climbing and walking on Exit Glacier. 13.1312 Section 13.1312 Parks...1312 Climbing and walking on Exit Glacier. Except for areas designated by the...climbing or walking on, in, or under Exit Glacier is prohibited within 1/2 mile...

2013-07-01

401

36 CFR 13.1312 - Climbing and walking on Exit Glacier.  

Code of Federal Regulations, 2012 CFR

... false Climbing and walking on Exit Glacier. 13.1312 Section 13.1312 Parks...1312 Climbing and walking on Exit Glacier. Except for areas designated by the...climbing or walking on, in, or under Exit Glacier is prohibited within 1/2 mile...

2012-07-01

402

A Walk-Through Programmed Robot for Welding in Shipyards Marcelo H. Ang Jr.*, Wei Lin#  

E-print Network

1 A Walk-Through Programmed Robot for Welding in Shipyards Marcelo H. Ang Jr.*, Wei Lin# and Ser: · Walk-through programming · Robotic welding · Automation in shipyards · Dynamic control Industrial Robot, Vol. 26, No. 5, 1999, pp. 377-388. #12;1 A Walk-Through Programmed Robot for Welding in Shipyards

Ang Jr.,, Marcelo H.

403

Powered Ankle-Foot Prosthesis for the Improvement of Amputee Walking Economy  

E-print Network

Powered Ankle-Foot Prosthesis for the Improvement of Amputee Walking Economy by Samuel Kwok-Wai Au LIBRARIES #12;#12;Powered Ankle-Foot Prosthesis for the Improvement of Amputee Walking Economy by Samuel The human ankle provides a significant amount of net positive work during the stance period of walking

Herr, Hugh

404

Through Rain, Sleet, Ice, and Snow, the Walking School Bus Still Must Go!  

ERIC Educational Resources Information Center

In this article, the author describes the walking school bus--a physically active and safe method in which young learners can travel to and from school while accompanied by adult volunteers. The walking school bus provides a safe and healthy way for elementary-age children to travel to and from school. Many families who live within walking

Paquette, Kelli R.

2007-01-01

405

16 CFR 1205.5 - Walk-behind rotary power mower controls.  

Code of Federal Regulations, 2012 CFR

...2012-01-01 false Walk-behind rotary power mower controls. 1205.5 Section 1205...REGULATIONS SAFETY STANDARD FOR WALK-BEHIND POWER LAWN MOWERS The Standard § 1205.5 Walk-behind rotary power mower controls. (a) Blade...

2012-01-01

406

16 CFR 1205.5 - Walk-behind rotary power mower controls.  

Code of Federal Regulations, 2013 CFR

...2013-01-01 false Walk-behind rotary power mower controls. 1205.5 Section 1205...REGULATIONS SAFETY STANDARD FOR WALK-BEHIND POWER LAWN MOWERS The Standard § 1205.5 Walk-behind rotary power mower controls. (a) Blade...

2013-01-01

407

16 CFR 1205.5 - Walk-behind rotary power mower controls.  

Code of Federal Regulations, 2011 CFR

...2011-01-01 false Walk-behind rotary power mower controls. 1205.5 Section 1205...REGULATIONS SAFETY STANDARD FOR WALK-BEHIND POWER LAWN MOWERS The Standard § 1205.5 Walk-behind rotary power mower controls. (a) Blade...

2011-01-01

408

16 CFR 1205.5 - Walk-behind rotary power mower controls.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 false Walk-behind rotary power mower controls. 1205.5 Section 1205...REGULATIONS SAFETY STANDARD FOR WALK-BEHIND POWER LAWN MOWERS The Standard § 1205.5 Walk-behind rotary power mower controls. (a) Blade...

2010-01-01

409

16 CFR 1205.5 - Walk-behind rotary power mower controls.  

Code of Federal Regulations, 2014 CFR

...2014-01-01 false Walk-behind rotary power mower controls. 1205.5 Section 1205...REGULATIONS SAFETY STANDARD FOR WALK-BEHIND POWER LAWN MOWERS The Standard § 1205.5 Walk-behind rotary power mower controls. (a) Blade...

2014-01-01

410

Detection of Abnormal Muscle Activations during Walking Following Spinal Cord Injury (SCI)  

ERIC Educational Resources Information Center

In order to identify optimal rehabilitation strategies for spinal cord injury (SCI) participants, assessment of impaired walking is required to detect, monitor and quantify movement disorders. In the proposed assessment, ten healthy and seven SCI participants were recruited to perform an over-ground walking test at slow walking speeds. SCI…

Wang, Ping; Low, K. H.; McGregor, Alison H.; Tow, Adela

2013-01-01

411

Modular control of human walking: A simulation study Richard R. Neptune a,, David J. Clark b  

E-print Network

activity across a wide range of walking speeds, levels of body weight support and other combined movement generated muscle-actuated forward dynamics simulations of normal walking using muscle activation modules the contributions of each module to the biomechanical sub-tasks of walking (i.e., body support, forward propulsion

412

Intro Comb Anal Prob Higher Dim Other Problems Moments and Densities of Short Random Walks  

E-print Network

Intro Comb Anal Prob Higher Dim Other Problems Moments and Densities of Short Random Walks New, 2014 Revised: 27-11-14 JMB/JW Short Random Walks #12;Intro Comb Anal Prob Higher Dim Other Problems and early career researchers. JMB/JW Short Random Walks #12;Intro Comb Anal Prob Higher Dim Other Problems

Borwein, Jonathan

413

Neighborhood Environment and Adherence to a Walking Intervention in African American Women  

ERIC Educational Resources Information Center

This secondary analysis examined relationships between the environment and adherence to a walking intervention among 252 urban and suburban, midlife African American women. Participants received an enhanced or minimal behavioral intervention. Walking adherence was measured as the percentage of prescribed walks completed. Objective measures of the…

Zenk, Shannon N.; Wilbur, JoEllen; Wang, Edward; McDevitt, Judith; Oh, April; Block, Richard; McNeil, Sue; Savar, Nina

2009-01-01

414

Shake-Your-Head: Revisiting Walking-In-Place for Desktop Virtual Reality Leo Terziman  

E-print Network

Shake-Your-Head: Revisiting Walking-In-Place for Desktop Virtual Reality L´eo Terziman INSA / INRIA it notably to the context of desktop Virtual Reality. With our novel "Shake-Your-Head" technique, the user.7 [Computer Graphics]: Three- Dimensional Graphics and Realism--Virtual Reality Keywords: Walking, Walking

Paris-Sud XI, Université de

415

Nordic Walking improves daily physical activities in COPD: a randomised controlled trial  

Microsoft Academic Search

BACKGROUND: In patients with COPD progressive dyspnoea leads to a sedentary lifestyle. To date, no studies exist investigating the effects of Nordic Walking in patients with COPD. Therefore, the aim was to determine the feasibility of Nordic Walking in COPD patients at different disease stages. Furthermore we aimed to determine the short- and long-term effects of Nordic Walking on COPD

Marie-Kathrin Breyer; Robab Breyer-Kohansal; Georg-Christian Funk; Nicole Dornhofer; Martijn A Spruit; Emiel FM Wouters; Otto C Burghuber; Sylvia Hartl

2010-01-01

416

Walking for Health in Pregnancy: Assessment by Indirect Calorimetry and Accelerometry  

ERIC Educational Resources Information Center

The purpose of this study was to examine RT3 accelerometer activity counts and activity energy expenditure of 36 pregnant women at 20 and 32 weeks' gestation during treadmill walking and free-living conditions. During treadmill walking, oxygen consumption was collected, and activity energy expenditure was estimated for a 30-min walk at a…

DiNallo, Jennifer M.; Le Masurier, Guy C.; Williams, Nancy I.; Downs, Danielle Symons

2008-01-01

417

Muscle activity and heart rate response during backward walking in water and on dry land  

Microsoft Academic Search

The primary purpose of this study was to examine whether walking backward in water and walking backward on dry land elicit different electromyographic (EMG) activities in lower-extremity and trunk muscles. Surface EMG was used to evaluate muscle activities while six healthy subjects walked backward in water (with and without a water current, Water + Cur and Water - Cur, respectively)

Kenji Masumoto; Shin-ichiro Takasugi; Noboru Hotta; Kazutaka Fujishima; Yukihide Iwamoto

2005-01-01

418

Age-related differences in dual task walking: a cross sectional study  

Microsoft Academic Search

BACKGROUND: Variability in stride velocity during walking characterizes gait instability and predicts falling in older individuals. Walking while executing a cognitive task is also associated with increased risk of falling, particularly in older adults. Variability in stride velocity, particularly during dual task walking conditions, may differ between younger and older individuals. The purpose of this study was to examine whether

Andrew W Priest; Kathleen B Salamon; John H Hollman

2008-01-01

419

Knuckle-walking anteater: A convergence test of adaptation for purported knuckle-walking features of african Hominidae  

Microsoft Academic Search

ABSTRACT,Appeals,to synapomorphic,features,of the wrist and hand in African apes, early hominins, and mod- ern,humans,as evidence,of knuckle-walking,ancestry,for the,hominin,lineage,rely on,accurate,interpretations,of those,features,as adaptations,to knuckle-walking,locomo- tion. Because Gorilla, Pan ,a ndHomo share a relatively close common ancestor, the interpretation of such features is confounded,somewhat,by phylogeny. The study presented here examines,the evolution,of a similar locomotor,regime in New World anteaters (order Xenarthra, family Myrme- cophagidae),and,uses,the,terrestrial,giant,anteater (Myrmecophaga,tridactyla)

Caley M. Orr

2005-01-01

420

Walking to Olympus: An EVA Chronology  

NASA Technical Reports Server (NTRS)

Spacewalkers enjoy a view of Earth once reserved for Apollo, Zeus, and other denizens of Mt. Olympus. During humanity's first extravehicular activity (EVA), Alexei Leonov floated above Gibraltar, the rock ancient seafarers saw as the gateway to the great unknown Atlantic. The symbolism was clear, Leonov stepped past a new Gibraltar when he stepped into space. More than 32 years and 154 EVAs later, Jerry Linenger conducted an EVA with Vladimir Tsibliyev as part of International Space Station Phase 1. They floated together above Gibraltar. Today the symbolism has new meaning: humanity is starting to think of stepping out of Earth orbit, space travel's new Gibraltar, and perhaps obtaining a new olympian view, a close-up look at Olympus Mons on Mars. Walking to Olympus: An EVA Chronology chronicles the 154 EVAs conducted from March 1965 to April 1997. It is intended to make clear the crucial role played by EVA in the history of spaceflight, as well as to chronicle the large body of EVA "lessons learned." Russia and the U.S. define EVA differently. Russian cosmonauts are said to perform EVA any time they are in vacuum in a space suit. A U.S. astronaut must have at least his head outside his spacecraft before he is said to perform an EVA. The difference is based in differing spacecraft design philoso- phies. Russian and Soviet spacecraft have always had a specialized airlock through which the EVA cosmonaut egressed, leaving the main habitable volume of the spacecraft pressurized. The U.S. Gemini and Apollo vehicles, on the other hand, depressurized their entire habitable volume for egress. In this document, we apply the Russian definition to Russian EVAS, and the U.S. definition to U.S. EVAS. Thus, for example, Gemini 4 Command Pilot James McDivitt does not share the honor of being first American spacewalker with Ed White, even though he was suited and in vacuum when White stepped out into space. Non-EVA spaceflights are listed in the chronology to provide context and to display the large num- ber of flights in which EVA played a role. This approach also makes apparent significant EVA gaps, for example, the U.S. gap between 1985 and 1991 following the Challenger accident. This NASA History Monograph is an edited extract from an extensive EVA Chronology and Reference Book being produced by the EVA Project Office, NASA Johnson Space Center, Houston, Texas. The larger work will be published as part of the NASA Formal Series in 1998. The authors gratefully acknowledge the assistance rendered by Max Ary, Ashot Bakunts, Gert-Jan Bartelds, Frank Cepollina, Andrew Chaikin, Phillip Clark, Richard Fullerton, Steven Glenn, Linda Godwin, Jennifer Green, Greg Harris, Clifford Hess, Jeffrey Hoffman, David Homan, Steven Hopkins, Nicholas Johnson, Eric Jones, Neville Kidger, Joseph Kosmo, Alexei Lebedev, Mark Lee, James LeBlanc, Dmitri Leshchenskii, Jerry Linenger, Igor Lissov, James McBarron, Clay McCullough, Joseph McMann, Story Musgrave, Dennis Newkirk, James Oberg, Joel Powell, Lee Saegesser, Andy Salmon, Glen Swanson, Joseph Tatarewicz, Kathy Thornton, Chris Vandenberg, Charles Vick, Bert Vis, David Woods, Mike Wright, John Young, and Keith Zimmerman. Special thanks to Laurie Buchanan, John Charles, Janet Kovacevich, Joseph Loftus, Sue McDonald, Martha Munies, Colleen Rapp, and Jerry Ross. Any errors remain the responsibility of the authors.

Portree, David S. F.; Trevino, Robert C.

1997-01-01

421

Physical Activity and Walking Onset in Infants with Down Syndrome  

ERIC Educational Resources Information Center

Infants with Down syndrome (DS) are described as being less active and they also experience significant delays in motor development. It is hypothesized that early infant physical activity may be influential for the acquisition of independent walking. Physical activity was monitored longitudinally in 30 infants with DS starting at an average age of…

Lloyd, Meghann; Burghardt, Amy; Ulrich, Dale A.; Angulo-Barroso, Rosa

2010-01-01

422

The effect of a pedometer-based community walking intervention \\  

Microsoft Academic Search

BACKGROUND: Recent systematic reviews have suggested that pedometers may be effective motivational tools to promote walking. However, studies tend to be of a relatively short duration, with small clinical based samples. Further research is required to demonstrate their effectiveness in adequately powered, community based studies. OBJECTIVE: Using a randomized controlled trial design, this study assessed the impact of a 12-week

Graham Baker; Stuart R Gray; Annemarie Wright; Claire Fitzsimons; Myra Nimmo; Ruth Lowry; Nanette Mutrie

2008-01-01

423

Change in Smoking, Diet, and Walking for Exercise in Blacks  

ERIC Educational Resources Information Center

Positive changes in one health behavior may be accompanied by other constructive health behavior changes. Thus, the authors investigated the association of smoking reduction and cessation to changes in fruit and vegetable (FV) intake and engaging in walking for exercise. This study included 539 Black light smokers ([less than or equal to]10…

Berg, Carla J.; Thomas, Janet L.; An, Lawrence C.; Guo, Hongfei; Collins, Tracie; Okuyemi, Kolawole S.; Ahluwalia, Jasjit S.

2012-01-01

424

RESEARCH Open Access Predictors of decline in walking ability in  

E-print Network

subjects (71.20% women; mean age 77.84 Standard Deviation, SD, 6.82 years, Mini-Mental State Examination 20.66). After adjustment for confounders, the risk of decline in walking ability was independently associated with older age (Relative Risk, RR = 1.05 (95% CI 1.02 to 1.08)), time from diagnosis of dementia (RR = 1

Paris-Sud XI, Université de

425

CAN KIRKMAN'S SCHOOLGIRLS WALK ABREAST BY FORMING ARITHMETIC PROGRESSIONS ?  

E-print Network

CAN KIRKMAN'S SCHOOLGIRLS WALK ABREAST BY FORMING ARITHMETIC PROGRESSIONS ? Lorenz Halbeisen an arithmetic progression modulo v with common difference d. It will be shown that smooth Kirkman triple systems our attention to arithmetic progressions in cyclic groups. Let v be a positive integer and let a, b, c

Halbeisen, Lorenz

426

CAN KIRKMAN'S SCHOOLGIRLS WALK ABREAST BY FORMING ARITHMETIC PROGRESSIONS ?  

E-print Network

CAN KIRKMAN'S SCHOOLGIRLS WALK ABREAST BY FORMING ARITHMETIC PROGRESSIONS ? Lorenz Halbeisen an arithmetic progression modulo v with common di#11;erence d. It will be shown that smooth Kirkman triple of the problem [1].) Now we turn our attention to arithmetic progressions in cyclic groups. Let v be a positive

Halbeisen, Lorenz

427

Properties of the escape system of cockroaches during walking  

Microsoft Academic Search

1.Adult male cockroaches (Periplaneta americana) which were fixed in place but could move their legs normally were presented with wind puffs of different amplitudes. The puffs were given while the cockroaches were walking at different speeds, standing or grooming their antennae. In different experiments we recorded either the movement responses of one metathoracic leg or the action potentials from impaled,

Jeffrey M. Camhi; Thomas G. Nolen

1981-01-01

428

[Familiarization to treadmill walking in unimpaired Parkinson's disease patients.  

PubMed

Familiarization to treadmill walking in unimpaired Parkinson's disease (PD) patients is assessed, across multiple treadmill walking sessions. Thirteen PD subjects were enrolled into the study (Eight were in a moderate stage of the disease, and 5 in an advanced stage). PD subjects attended a progressive program consisting of 12 sessions of 20 min. Walking speed, cadence, step length and coefficient of variation were assessed. ANOVA test were used to evaluate progression of disease and time influence over familiarization. PD Subjects baseline characteristics did not differ significantly between both groups and typical dependencies over progression of disease and velocity were found for cadence, step length and coefficient of variation. However, we showed that some PD subjects may require longer familiarization times and that familiarization is an adaptation process which involves parameters as velocity, cadence and gait stability. A better definition of familiarization to treadmill is needed since some parameters such as step length does not change significantly while others such as cadence, coefficient of variation and intraclass correlation coefficient does. Therefore familiarization to treadmill walking should remain on measures of velocity, cadence, reliability and variability. However, a bigger sample size is needed in order to improve the results of the present study. PMID:25264794

Pérez-Sanpablo, Alberto Isaac; Hernández-Arenas, Claudia; Rodríguez-Reyes, Gerardo; Quiñones-Uriostegui, Ivett; Alessi Montero, Aldo; Núñez-Carrera, Lidia; Boll-Woehrlen, Marie Catherine; Galván Duque-Gastélum, Carlos

2014-07-01

429

How Big Is the Random Walk in GNP?  

Microsoft Academic Search

This paper presents a measure of the persistence of fluctuations in gross national product (GNP) based on the variance of its long differences. That measure finds little long-term persistence in GNP. Previous research on this question found a great deal of persistence in GNP, suggesting models such as a random walk. A reconciliation of this paper's results with previous research

John H. Cochrane

1988-01-01

430

Learning Walks: Build Hearty Appetites for Professional Development  

ERIC Educational Resources Information Center

Mike Carbone has been the principal of Kickemuit Middle School in Warren, Rhode Island, since 1990. He's seen some bad times there before a dramatic turnaround. When asked what finally got his school's engine revved and moving the school forward, he said without hesitation: "Learning walks." In this article, the author describes how Carbone…

Steiny, Julia

2009-01-01

431

I-WALK: An Innovative Approach to Community Walkability  

ERIC Educational Resources Information Center

One way of combating rising obesity rates and decreasing physical activity levels among children is to promote active transportation to and from schools. The award-winning I-WALK program provides a comprehensive framework for addressing community walkability and related infrastructure. The program uses a unique and innovative methodology that…

Seeger, Christopher J.; Lillehoj, Catherine J.; Jensen, Alan D.; Wilson, Suzy; Levinson, Lydia R.

2014-01-01

432

Length of adaptive walk on uncorrelated and correlated fitness landscapes  

NASA Astrophysics Data System (ADS)

We consider the adaptation dynamics of an asexual population that walks uphill on a rugged fitness landscape which is endowed with a large number of local fitness peaks. We work in a parameter regime where only those mutants that are a single mutation away are accessible, as a result of which the population eventually gets trapped at a local fitness maximum and the adaptive walk terminates. We study how the number of adaptive steps taken by the population before reaching a local fitness peak depends on the initial fitness of the population, the extreme value distribution of the beneficial mutations, and correlations among the fitnesses. Assuming that the relative fitness difference between successive steps is small, we analytically calculate the average walk length for both uncorrelated and correlated fitnesses in all extreme value domains for a given initial fitness. We present numerical results for the model where the fitness differences can be large and find that the walk length behavior differs from that in the former model in the Fréchet domain of extreme value theory. We also discuss the relevance of our results to microbial experiments.

Seetharaman, Sarada; Jain, Kavita

2014-09-01

433

Random walks and random numbers from supercontinuum generation  

E-print Network

Random walks and random numbers from supercontinuum generation Benjamin Wetzel,1 Keith J. Blow,2 supercontinuum provides a highly versatile means of study- ing and generating a wide class of random processes; (320.6629) Supercontinuum generation; (190.3100) Instabilities and chaos; (320.7110) Ultrafast

Turitsyn, Sergei K.

434

Online ZMP Sampling Search for Biped Walking Planning  

E-print Network

plan- ners; the robot is able to achieve the motions and keep its balance using the feedback from its in footstep planning and other motions of humanoid robots [10]. RRT employs a random method to find a solution of the algorithm by successful combined walking tasks in a faithful simulation of a full-body humanoid robot. Index

Veloso, Manuela M.

435

Kinematic and stability motion limits for a hexapod walking machine  

NASA Astrophysics Data System (ADS)

The major problem addressed by this research is to investigate and implement the basic concepts necessary to lay the groundwork for efficient forms of motion planning, motion control, and gait algorithms with respect to hexapod walking machines. Specifically, the approach taken was to develop and implement the concepts of a stability margin and a joint space motion margin on an object-oriented representation of the Aquarobot. The model was generated in Franz Common Lisp and simulated via Allegro Common Windows. A method by which distance computations can be calculated and applied to the center of mass and triangular support pattern of a walking machine to determine the stability margin is introduced. Inverse kinematics and joint limits are utilized to ascertain the joint space motion margin of the model. Response to impending instability and the effect when a joint hits or approaches a joint kinematic limit on the motion of the hexapod walking machine by stopping the model is also addressed. The results are as follows: the concepts of the joint space motion margin and the stability margin can be successfully implemented on a kinematic model and graphical simulation of a hexapod walking machine. These concepts contribute to future work in the area of more efficient free gait algorithms, specifically asynchronous gait algorithms.

Dunton, Elizabeth M.

1995-03-01

436

Walking Behaviours among Adolescent Girls in Scotland: A Pilot Study  

ERIC Educational Resources Information Center

Purpose: The wide ranging physical and mental health benefits of physical activity during adolescence are well established and walking has been identified as one of only two forms of physical activity not to show a significant decrease in participation levels across the primary/secondary years. The aim of this paper is to explore the broader…

Kirby, Joanna; Inchley, Jo

2013-01-01

437

On the recurrence set of planar Markov Random Walks  

E-print Network

In this paper, we investigate the properties of recurrent planar Markov random walks. More precisely, we study the set of recurrent points with the use of local limit theorems. The Nagaev-Guivarc'h spectral method provides several examples for which these local limit theorems are satisfied as soon as the (standard or non-standard) central limit theorem holds.

Hervé, Loïc

2012-01-01

438

Quenched Central Limit Theorems for Random Walks in Random Scenery  

E-print Network

in random scenery; Limit theorem; Local time. AMS Subject Classification: 60F05, 60G52. This workQuenched Central Limit Theorems for Random Walks in Random Scenery Nadine Guillotin-similar stochastic processes. Functional limit theorems for RWRS have been first obtained under the product measure P

Paris-Sud XI, Université de

439

A LOCAL LIMIT THEOREM FOR RANDOM WALKS IN BALANCED ENVIRONMENTS  

E-print Network

A LOCAL LIMIT THEOREM FOR RANDOM WALKS IN BALANCED ENVIRONMENTS MIKKO STENLUND Abstract. Central in the past years. More recently still, finer local limit theorems -- yielding a Gaussian density multiplied. Balanced random environment, local limit theorem, Nash inequality. 1 #12;2 MIKKO STENLUND Knowing

440

Dog Ownership, Dog Walking, and Children's and Parents' Physical Activity  

ERIC Educational Resources Information Center

This study aimed to determine cross-sectional associations of dog ownership, dog walking, and physical activity (PA) among children and their parents. Objective measures of PA were obtained for children ages 5-6 and 10-12 years from 19 primary schools across Melbourne, Australia. Parents self-reported their PA, dog ownership, and frequency of dog…

Salmon, Jo; Timperio, Anna; Chu, Binh; Veitch, Jenny

2010-01-01

441

Association between Muscle Synergy and Stability during Prolonged Walking  

PubMed Central

[Purpose] The purpose of this study was to examine whether changes in muscle synergy could affect gait stability or muscle activity by comparing muscle activity before and after prolonged walking. [Subjects and Methods] Twelve healthy male subjects walked on a treadmill for 10?min as a warm-up. Data were recorded from the participants during the first and last 1?min during 90?min of walking at 4.5?km/h. Electromyographic (EMG) activity was recorded for 7 leg muscles, and patterns of coordination were determined by principal component analysis (PCA). The patterns of activity within the anatomic muscle groups were additionally determined by repeating PCA. iEMG was calculated using the mean EMG for each cycle step during the 1?min walking periods. The largest Lyapunov exponent was calculated to quantify each subject’s inherent local dynamic stability. [Results] The patterns for each of the 7 muscles showed no change between the start and end periods. However, the end period showed a higher co-activation of the triceps surae, lower iEMG of the medial gastrocnemius, and a smaller largest Lyapunov exponent of the mediolateral and anteroposterior directions than those observed during the start period. [Conclusion] The increase in triceps surae co-activation may be associated with gait stability. PMID:25364133

Suzuki, Keisuke; Nishida, Yusuke; Mitsutomi, Kazuhiko

2014-01-01

442

0g Climbing - The Challenge of Walking in Space  

NASA Technical Reports Server (NTRS)

Space walking is poorly named, as it has little in common with how animals walk on Earth. Space walking is more akin to mountain climbing in scuba gear, while parachuting in a freefall -- an odd combination of effects and equipment to help people do a demanding job. Robots are now being studied for service in this same domain, working on large scale space structures like the Space Station, servicing science or military platforms in high orbit, or riding on the outside of a space craft in transit to Mars, the Moon or other destinations. What have we learned about climbing in 0g? How should machines be controlled for serving in this role? What can they do to overcome the problems that humans have faced? In order to move about in this environment, a robot must be able to climb autonomously, using gaits that smoothly manage its momentum and that minimize contact forces (walking lightly) while providing for safety in the event of an emergency requiring the system to stop. All three of these objectives are now being explored at NASA's Johnson Space Center, using the Robonaut system and a set of mockups that emulate the 0g condition. NASA's goal for Robonaut is to develop the control technology that will allow it to climb on the outside of the Space Shuttle, the Space Station, and satellite mockups at JSC, enabling the robot to perform EVA task setups or serve as an Astronaut's assistant.

Ambrose, Robert O.; Rehnmark, Frederik; Goza, Michael

2003-01-01

443

0g Climbing - The Challenge of Walking in Space  

NASA Technical Reports Server (NTRS)

Space walking is poorly named, as it has little in common with how animals walk on Earth. Space walking is more akin to mountain climbing in scuba gear, while parachuting in a freefall-an odd combination of effects and equipment to help people do a demanding job. Robots are now being studied for service in this same domain, working on large scale space structures like the Space Station, servicing science or military platforms in high orbit, or riding on the outside of a space craft in transit to Mars, the Moon or other destinations. What have we learned about climbing in 0g? How should machines be controlled for serving in this role? What can they do to overcome the problems that humans have faced? In order to move about in this environment, a robot must be able to climb autonomously, using gaits that smoothly manage its momentum and that minimize contact forces (walking lightly) while providing for safety in the event of an emergency requiring the system to stop. All three of these objectives are now being explored at NASA's Johnson Space Center, using the Robonaut system and a set of mockups that emulate the 0g condition. NASA's goal for Robonaut is to develop the control technology that will allow it to climb on the outside of the Space Shuttle, the Space Station, and satellite mockups at JSC, enabling the robot to perform EVA task setups or serve as an Astronaut's assistant.

Ambrose, Robert O.; Rehnmark, Frederik; Goza, Michael

2004-01-01

444

Tesselation of 3D by waveguides: random walk and computation  

NASA Astrophysics Data System (ADS)

A major drawback of lightwave circuits (LWCs) is the nearest- neighbor (NN) interconnection scheme. An attempt to overcome within the technological restrictions is the repetitive triangulation (RTR) of the proposed N-gon cell complexes. (Higher-order RTR is aimed to be done in the frequency domain.) The 2-D LWCs are analyzed by (1) 2-D models (projection onto the plane) and (2) 3-D models. The 2-D models are (a) orthogonal 2-D grids where faulty edges comes in and (b) double triangulated 2-D grids for the embedding of the N- gon cell complexes subject to RTR. The 3-D models are (i) orthogonal 3-D grids and (ii) orthogonal 3-D grids with triangulated plane facets as spatial triangulation causes a topology which is difficult to realize by LWCs. The random walks within these architectures are considered. Random walks in orthogonal grids are known to exhibit different properties dependent on the dimension. These properties have to do with the propagation in all 2d directions (d is the dimension). The question arises whether these properties are obtainable also within the proposed feed-forward (FF) networks where backward couplings are excluded. As an approach to control these random walk characteristics (synthesis) the biased random walk is proposed.

Giglmayr, Josef

2001-12-01

445

Einstein's random walk and thermal diffusion Yong-Jung Kim  

E-print Network

Einstein's random walk and thermal diffusion Yong-Jung Kim Department of Mathematical Sciences. Here, u is the particle concentration in space dimensions #12;2 Yong-Jung Kim n 1, u = u x1, Carl Ludwig [21] found in 1856 that, if a tem- perature gradient T is applied across a uniformly

Kim, Yong Jung

446

Make a Wire Critter That Can Walk on Water  

NSDL National Science Digital Library

In this activity, learners make water-walking critters using thin wire, and then test how many paper clips these critters can carry without sinking. Watch the Science Friday video "Stroke of the Water Strider" on this page to learn about a robot that was inspired by insects' ability to travel on the surface of water.

Ariel Zych

2014-06-23

447

Adaptive importance sampling of random walks on continuous state spaces  

SciTech Connect

The authors consider adaptive importance sampling for a random walk with scoring in a general state space. Conditions under which exponential convergence occurs to the zero-variance solution are reviewed. These results generalize previous work for finite, discrete state spaces in Kollman (1993) and in Kollman, Baggerly, Cox, and Picard (1996). This paper is intended for nonstatisticians and includes considerable explanatory material.

Baggerly, K.; Cox, D.; Picard, R.

1998-11-01

448

Effects of asymmetric load carrying on the biomechanics of walking.  

PubMed

The purpose of the study was to investigate the effects of an asymmetric sidepack carrying system on frontal plane joint moments of force in both lower extremities and in the L5/S1 joint during level walking. Ground reaction force data and frontal plane film records were obtained from five males performing three walking conditions: 0, 10 and 20% bodyweight loads in a sidepack supported by the left shoulder. Inverse dynamics were used to calculate the lower extremity moments during stance and a static model of the pelvis was used to calculate the L5/S1 moments during single support for each limb. Normal walking was characterized by symmetric kinetics between left and right limbs and around the L5/S1 joint. The asymmetric loads produced unbalanced lateral trunk muscle dominance between left and right limb stance phases, increased right hip and knee moments and decreased left hip and knee moments. During normal walking, the L5/S1 moment was dominant on the contralateral trunk side for both limbs. The asymmetric loads applied to the left side caused a shift in L5/S1 moment dominance to the right side during left and right single support phases. PMID:1769977

DeVita, P; Hong, D; Hamill, J

1991-01-01

449

A Random Walk Approach for Light Scattering in Material  

Microsoft Academic Search

Understanding reflection is one of the key competences in graphic arts industry. A very popular approach was given by KUBELKA and MUNK (1) who derived a simple relationship between the scattering and absorption coefficients and the overall reflectance. This paper presents an alternative approach which describes the behavior of light in matter as a special kind of random walk.

Klaus Simon; Beat Trachsler

2003-01-01

450

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

E-print Network

simple robots and human experiments to show that arm swinging is both easy and beneficial. The movement swinging is a vestigial relic from our quadrupedal ancestors," said Steven Collins, a biomechanical through his work with walking robots, which he uses to test ideas about human locomotion. He works

Collins, Steven H.

451

Grand Canyon Trekkers: School-Based Lunchtime Walking Program  

ERIC Educational Resources Information Center

The incidence of childhood overweight is especially troubling among low income Latino youth. Grand Canyon Trekkers (GCT) was implemented as a quasi-experimental study in 10 Title 1 elementary schools with a large Latino population to examine the effects of a 16-week structured walking program on components of health-related physical fitness: Body…

Hawthorne, Alisa; Shaibi, Gabriel; Gance-Cleveland, Bonnie; McFall, Sarah

2011-01-01

452

Understanding How Families Use Magnifiers during Nature Center Walks  

ERIC Educational Resources Information Center

This analysis uses a sociocultural learning theory and parent-child interaction framework to understand families' interactions with one type of scientific tool, the magnifier, during nature walks offered by a nature center. Families were video recorded to observe how they organized their activities where they used magnifiers to explore in the…

Zimmerman, Heather Toomey; McClain, Lucy Richardson; Crowl, Michele

2013-01-01

453

Linearly bounded liars, adaptive covering codes, and deterministic random walks  

E-print Network

University of South Carolina, Columbia, South Carolina cooper@math.sc.edu Robert B. Ellis Illinois Institute implicitly by Spencer and Winkler for the original liar game [12]. The second is to adapt the analysis of deterministic random walks on the integers, developed by the first author, Doerr, Spencer, and Tardos [3

Ellis, Robert B.

454

Human Body Detection that Uses Electric Field by Walking  

Microsoft Academic Search

For a method for detecting the human body, such factors that no blind corner should exist, subjects other than human beings will not be erroneously detected. In this paper, a new method for detecting a human body wherein attention is focused on the human characteristics of walking will be studied. It had been known that a human body is electrified

Kiyoaki Takiguchi; Takayuki Wada; Shigeki Toyama

2007-01-01

455

Oblique view of southeast and northeast sides with covered walk ...  

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

Oblique view of southeast and northeast sides with covered walk to Facility 367, Facility 324 beyond, view facing west - U.S. Naval Base, Pearl Harbor, Naval Hospital, Animal House, Near intersection of Hospital Way & Third Street, Pearl City, Honolulu County, HI

456

Neuromuscular activation patterns during treadmill walking after space flight  

NASA Technical Reports Server (NTRS)

Astronauts adopt a variety of neuromuscular control strategies during space flight that are appropriate for locomoting in that unique environment, but are less than optimal upon return to Earth. We report here the first systematic investigation of potential adaptations in neuromuscular activity patterns associated with postflight locomotion. Astronaut-subjects were tasked with walking on a treadmill at 6.4 km/h while fixating a visual target 30 cm away from their eyes after space flights of 8-15 days. Surface electromyography was collected from selected lower limb muscles and normalized with regard to mean amplitude and temporal relation to heel strike. In general, high correlations (more than 0.80) were found between preflight and postflight activation waveforms for each muscle and each subject: however relative activation amplitude around heel strike and toe off was changed as a result of flight. The level of muscle cocontraction and activation variability, and the relationship between the phasic characteristics of the ankle musculature in preparation for toe off also were altered by space flight. Subjects also reported oscillopsia during treadmill walking after flight. These findings indicate that, after space flight, the sensory-motor system can generate neuromuscular-activation strategies that permit treadmill walking, but subtle changes in lower-limb neuromuscular activation are present that may contribute to increased lower limb kinematic variability and oscillopsia also present during postflight walking.

Layne, C. S.; McDonald, P. V.; Bloomberg, J. J.

1997-01-01

457

The Random Walk Drainage Simulation Model as a Teaching Exercise  

ERIC Educational Resources Information Center

Practical instructions about using the random walk drainage network simulation model as a teaching excercise are given and the results discussed. A source of directional bias in the resulting simulated drainage patterns is identified and given an interpretation in the terms of the model. Three points of educational value concerning the model are…

High, Colin; Richards, Paul

1972-01-01

458

Decoherent quantum walks driven by a generic coin operation  

Microsoft Academic Search

We consider the effect of different unitary noise mechanisms on the evolution of a quantum walk (QW) on a linear chain with a generic coin operation: (i) bit-flip channel noise, restricted to the coin subspace of the QW and (ii) topological noise caused by randomly broken links in the linear chain. Similarities and differences in the respective decoherent dynamics of

G. Abal; R. Donangelo; F. Severo; R. Siri

2008-01-01

459

Loci communes and thoreau's arguments for wilderness in “walking” (1851)  

Microsoft Academic Search

Perelman and Olbrechts?Tyteca's concept of loci communes is investigated for its contributions to a critical methodology. It is argued that discourse relying upon different loci may lead to different construals of the APPEARANCE?REALITY pair and, hence, to different interpretations of the value of a given object, idea, or action. Analyses of Henry David Thoreau's “Walking” (1851) and other Transcendentalist writings

J. Robert Cox

1980-01-01

460

Flight Director Robert Castle uses laptop while monitoring space walk  

NASA Technical Reports Server (NTRS)

Flight Director Robert E. Castle uses a laptop computer to aid his busy tasks during one of the five space walks performed to service the Hubble Space Telescope (HST) temporarily berthed in Endeavour's cargo bay. STS-61 lead Flight Director Milt Heflin is at right edge of frame.

1993-01-01

461

Facilitating Walking by Young Children with Visual Impairments.  

ERIC Educational Resources Information Center

Discussion of ways to encourage walking by young children with visual impairments first notes factors that constrain motor development. Suggestions include providing incentives for movement, building trust, fostering postural readiness, encouraging cruising, utilizing familiar spaces and short distances, and using protective and support devices…

Lowry, Susan Shier; Hatton, Deborah D.

2002-01-01

462

Generalized Levy-walk model for DNA nucleotide sequences  

NASA Technical Reports Server (NTRS)

We propose a generalized Levy walk to model fractal landscapes observed in noncoding DNA sequences. We find that this model provides a very close approximation to the empirical data and explains a number of statistical properties of genomic DNA sequences such as the distribution of strand-biased regions (those with an excess of one type of nucleotide) as well as local changes in the slope of the correlation exponent alpha. The generalized Levy-walk model simultaneously accounts for the long-range correlations in noncoding DNA sequences and for the apparently paradoxical finding of long subregions of biased random walks (length lj) within these correlated sequences. In the generalized Levy-walk model, the lj are chosen from a power-law distribution P(lj) varies as lj(-mu). The correlation exponent alpha is related to mu through alpha = 2-mu/2 if 2 < mu < 3. The model is consistent with the finding of "repetitive elements" of variable length interspersed within noncoding DNA.

Buldyrev, S. V.; Goldberger, A. L.; Havlin, S.; Simons, M.; Stanley, H. E.

1993-01-01

463

Performance of redirected walking algorithms in a constrained virtual world.  

PubMed

Redirected walking algorithms imperceptibly rotate a virtual scene about users of immersive virtual environment systems in order to guide them away from tracking area boundaries. Ideally, these distortions permit users to explore large unbounded virtual worlds while walking naturally within a physically limited space. Many potential virtual worlds are composed of corridors, passageways, or aisles. Assuming users are not expected to walk through walls or other objects within the virtual world, these constrained worlds limit the directions of travel and as well as the number of opportunities to change direction. The resulting differences in user movement characteristics within the physical world have an impact on redirected walking algorithm performance. This work presents a comparison of generalized RDW algorithm performance within a constrained virtual world. In contrast to previous studies involving unconstrained virtual worlds, experimental results indicate that the steer-to-orbit keeps users in a smaller area than the steer-to-center algorithm. Moreover, in comparison to steer-to-center, steer-to-orbit is shown to reduce potential wall contacts by over 29%. PMID:24650985

Hodgson, Eric; Bachmann, Eric; Thrash, Tyler

2014-04-01

464

"Walking" Along a Free Rotating Bicycle Wheel (Round and Round)  

NASA Astrophysics Data System (ADS)

We describe the kinematics, dynamics, and also some energy issues related to Marta mouse's motion when she walks on top of a horizontal bicycle wheel, which is free to rotate like a merry-go-round, as presented recently by Paul Hewitt in the "Figuring Physics" section of this journal. The situation is represented in Fig. 1, which was taken from Ref. 1.

Güémez, J.; Fiolhais, M.

2015-02-01

465

Length of adaptive walk on uncorrelated and correlated fitness landscapes.  

PubMed

We consider the adaptation dynamics of an asexual population that walks uphill on a rugged fitness landscape which is endowed with a large number of local fitness peaks. We work in a parameter regime where only those mutants that are a single mutation away are accessible, as a result of which the population eventually gets trapped at a local fitness maximum and the adaptive walk terminates. We study how the number of adaptive steps taken by the population before reaching a local fitness peak depends on the initial fitness of the population, the extreme value distribution of the beneficial mutations, and correlations among the fitnesses. Assuming that the relative fitness difference between successive steps is small, we analytically calculate the average walk length for both uncorrelated and correlated fitnesses in all extreme value domains for a given initial fitness. We present numerical results for the model where the fitness differences can be large and find that the walk length behavior differs from that in the former model in the Fréchet domain of extreme value theory. We also discuss the relevance of our results to microbial experiments. PMID:25314469

Seetharaman, Sarada; Jain, Kavita

2014-09-01

466

Map data 2012 Google -Walking directions are in beta.  

E-print Network

Map data ©2012 Google - Walking directions are in beta. Use caution ­ This route may be missing route accordingly. You must obey all signs or notices regarding your route. Map data ©2012 Google Hilton. Hilton Garden Inn West Lafayette Wabash Landing, 356 ... http://maps.google.com/ 1 of 1 06/29/2012 09

467

Walking Gait Optimization for Accommodation of Unknown Terrain Height Variations  

E-print Network

Walking Gait Optimization for Accommodation of Unknown Terrain Height Variations Brent Griffin of terrain height changes. Trajectory and control deviations are related to a nominal periodic orbit via that specifically account for trajectory and control-effort perturbations arising from a finite set of ground height

Grizzle, Jessy W.

468

Cellular Algebras and Graph Invariants Based on Quantum Walks  

E-print Network

We consider two graph invariants inspired by quantum walks- one in continuous time and one in discrete time. We will associate a matrix algebra called a cellular algebra with every graph. We show that, if the cellular algebras of two graphs have a similar structure, then they are not distinguished by either of the proposed invariants.

Jamie Smith

2011-03-01

469

Relevant subgraph extraction from random walks in a graph  

E-print Network

seed nodes. 1 #12;1 Introduction We address here the problem of extracting a subgraph that bestRelevant subgraph extraction from random walks in a graph P. Dupont, J. Callut, G. Dooms, J methods for extracting a subgraph that best captures the relationships between k given nodes of interest

Dupont, Pierre

470

Six minutes walk test for individuals with schizophrenia.  

PubMed

Abstract Purpose: The six-minute walk test (6MWT) is a sub-maximal exercise test measuring the distance that a patient can walk quickly in a period of 6 minutes (6MWD). The objectives of this systematic review are to evaluate the 6MWT's suitability for measuring the impact of an intervention, to compare the 6MWD walked by patients with schizophrenia with data for the general population or matched controls, to identify the determinants of 6MWD and to examine the measurement properties and quality procedures of the 6MWT. Methods: Using five databases, we performed a systematic review of full-text articles published through August 2013. Results: Sixteen studies met our selection criteria. The assessment of the 6MWT's suitability for measuring the impact of interventions was not made because none of the interventional studies reported a significant increase in 6MWD. The distance walked by adults with schizophrenia seemed generally shorter than that walked by healthy adults. Mean 6MWDs ranged from 421?m to 648?m in the included studies. The 6MWD is usually negatively associated with a higher Body Mass Index, increased cigarette consumption, higher doses of antipsychotic medication and lower physical self-worth in individuals with schizophrenia. The 6MWT demonstrates high reliability. To date, however, its criterion validity has not been investigated. In spite of existing guidelines, the test procedures used in the studies reviewed varied significantly. Conclusions: Future physical health monitoring recommendations for patients with schizophrenia should include the 6MWT. Future studies should investigate its predictive role and continue to assess its measurement properties. Implications for Rehabilitation The Six-Minute Walk Test reliably assesses the functional exercise capacity in patients with schizophrenia. The impact of therapeutic interventions on patients, as measured by the 6MWT, cannot be confirmed. Clinicians should take into account overweight, antipsychotic medication use and the physical self-perception when considering the functional exercise capacity in schizophrenia. Clinicians should follow International standards such as these of the American Thoracic Society when using the Six-Minute Walk Test in patients with severe mental illnesses. PMID:25098595

Bernard, P; Romain, A J; Vancampfort, D; Baillot, A; Esseul, E; Ninot, G

2014-08-01

471

Multisensory integration in the estimation of walked distances.  

PubMed

When walking through space, both dynamic visual information (optic flow) and body-based information (proprioceptive and vestibular) jointly specify the magnitude of distance travelled. While recent evidence has demonstrated the extent to which each of these cues can be used independently, less is known about how they are integrated when simultaneously present. Many studies have shown that sensory information is integrated using a weighted linear sum, yet little is known about whether this holds true for the integration of visual and body-based cues for travelled distance perception. In this study using Virtual Reality technologies, participants first travelled a predefined distance and subsequently matched this distance by adjusting an egocentric, in-depth target. The visual stimulus consisted of a long hallway and was presented in stereo via a head-mounted display. Body-based cues were provided either by walking in a fully tracked free-walking space (Exp. 1) or by being passively moved in a wheelchair (Exp. 2). Travelled distances were provided either through optic flow alone, body-based cues alone or through both cues combined. In the combined condition, visually specified distances were either congruent (1.0×) or incongruent (0.7× or 1.4×) with distances specified by body-based cues. Responses reflect a consistent combined effect of both visual and body-based information, with an overall higher influence of body-based cues when walking and a higher influence of visual cues during passive movement. When comparing the results of Experiments 1 and 2, it is clear that both proprioceptive and vestibular cues contribute to travelled distance estimates during walking. These observed results were effectively described using a basic linear weighting model. PMID:22411581

Campos, Jennifer L; Butler, John S; Bülthoff, Heinrich H

2012-05-01

472

Modification of cutaneous reflexes during visually guided walking.  

PubMed

Although it has become apparent that cutaneous reflexes can be adjusted based on the phase and context of the locomotor task, it is not clear to what extent these reflexes are regulated when locomotion is modified under visual guidance. To address this, we compared the amplitude of cutaneous reflexes while subjects performed walking tasks that required precise foot placement. In one experiment, subjects walked overground and across a horizontal ladder with narrow raised rungs. In another experiment, subjects walked and stepped onto a series of flat targets, which required different levels of precision (large vs. narrow targets). The superficial peroneal or tibial nerve was electrically stimulated in multiple phases of the gait cycle in each condition and experiment. Reflexes between 50 and 120 ms poststimulation were sorted into 10 equal phase bins, and the amplitudes were then averaged. In each experiment, differences in cutaneous reflexes between conditions occurred predominantly during swing phase when preparation for precise foot placement was necessary. For instance, large excitatory cutaneous reflexes in ipsilateral tibialis anterior were present in the ladder condition and when stepping on narrow targets compared with inhibitory responses in the other conditions, regardless of the nerve stimulated. In the ladder experiments, additional effects of walking condition were evident during stance phase when subjects had to balance on the narrow ladder rungs and may be related to threat and/or the unstable foot-surface interaction. Taken together, these results suggest that cutaneous reflexes are modified when visual feedback regarding the terrain is critical for successful walking. PMID:24155011

Ruff, Casey R; Miller, Andreas B; Delva, Mona L; Lajoie, Kim; Marigold, Daniel S

2014-01-01

473

Gaze shifts and fixations dominate gaze behavior of walking cats.  

PubMed

Vision is important for locomotion in complex environments. How it is used to guide stepping is not well understood. We used an eye search coil technique combined with an active marker-based head recording system to characterize the gaze patterns of cats walking over terrains of different complexity: (1) on a flat surface in the dark when no visual information was available, (2) on the flat surface in light when visual information was available but not required for successful walking, (3) along the highly structured but regular and familiar surface of a horizontal ladder, a task for which visual guidance of stepping was required, and (4) along a pathway cluttered with many small stones, an irregularly structured surface that was new each day. Three cats walked in a 2.5-m corridor, and 958 passages were analyzed. Gaze activity during the time when the gaze was directed at the walking surface was subdivided into four behaviors based on speed of gaze movement along the surface: gaze shift (fast movement), gaze fixation (no movement), constant gaze (movement at the body's speed), and slow gaze (the remainder). We found that gaze shifts and fixations dominated the cats' gaze behavior during all locomotor tasks, jointly occupying 62-84% of the time when the gaze was directed at the surface. As visual complexity of the surface and demand on visual guidance of stepping increased, cats spent more time looking at the surface, looked closer to them, and switched between gaze behaviors more often. During both visually guided locomotor tasks, gaze behaviors predominantly followed a repeated cycle of forward gaze shift followed by fixation. We call this behavior "gaze stepping". Each gaze shift took gaze to a site approximately 75-80cm in front of the cat, which the cat reached in 0.7-1.2s and 1.1-1.6 strides. Constant gaze occupied only 5-21% of the time cats spent looking at the walking surface. PMID:24973656

Rivers, T J; Sirota, M G; Guttentag, A I; Ogorodnikov, D A; Shah, N A; Beloozerova, I N

2014-09-01

474

Vertical reaction forces and kinematics of backward walking underwater.  

PubMed

The aim of this study was to compare the first and second peaks of the vertical ground reaction force (VGRF) and kinematics at initial contact (IC) and final stance (FS) during walking in one of two directions (forward×backward) and two environments (on land×underwater). Twenty-two adults (24.6±2.6 years) walking forward (FW) and backward (BW) on a 7.5m walkway with a central force plate. Underwater immersion was at the height of the Xiphoid process. Ten trials were performed for each condition giving a total of 40 trials where the VGRF and kinematic data were recorded. Two-way repeated measures analysis of covariance was used with a combination of environment and direction of walking: FW on land, FW underwater, BW on land and BW underwater (entered as between-subjects factor) and repeated measures of VGRF peaks (first and second) or angles (at IC and FS). Walking velocity was included as a covariate. Both VGRF peaks were reduced when participants walked underwater compared to on land (p<.001). For BW, in both environments, the second peak was lower than the first (p<.001; for both). During BW at IC the ankle is more dorsiflexed and the knee is more flexed, both on land and underwater. At FS, there was no difference between the ankle angle for FW and BW in both environments. At IC, in FW and BW the knee and hip are more flexed underwater. BW underwater involves a lower VGRF and more knee and hip flexion than BW on land. PMID:21993483

Carneiro, Leticia Calado; Michaelsen, Stella Maris; Roesler, Helio; Haupenthal, Alessandro; Hubert, Marcel; Mallmann, Eddy

2012-02-01

475

A reflexive neural network for dynamic biped walking control.  

PubMed

Biped walking remains a difficult problem, and robot models can greatly facilitate our understanding of the underlying biomechanical principles as well as their neuronal control. The goal of this study is to specifically demonstrate that stable biped walking can be achieved by combining the physical properties of the walking robot with a small, reflex-based neuronal network governed mainly by local sensor signals. Building on earlier work (Taga, 1995; Cruse, Kindermann, Schumm, Dean, & Schmitz, 1998), this study shows that human-like gaits emerge without specific position or trajectory control and that the walker is able to compensate small disturbances through its own dynamical properties. The reflexive controller used here has the following characteristics, which are different from earlier approaches: (1) Control is mainly local. Hence, it uses only two signals (anterior extreme angle and ground contact), which operate at the interjoint level. All other signals operate only at single joints. (2) Neither position control nor trajectory tracking control is used. Instead, the approximate nature of the local reflexes on each joint allows the robot mechanics itself (e.g., its passive dynamics) to contribute substantially to the overall gait trajectory computation. (3) The motor control scheme used in the local reflexes of our robot is more straightforward and has more biological plausibility than that of other robots, because the outputs of the motor neurons in our reflexive controller are directly driving the motors of the joints rather than working as references for position or velocity control. As a consequence, the neural controller and the robot mechanics are closely coupled as a neuromechanical system, and this study emphasizes that dynamically stable biped walking gaits emerge from the coupling between neural computation and physical computation. This is demonstrated by different walking experiments using a real robot as well as by a Poincaré map analysis applied on a model of the robot in order to assess its stability. PMID:16595061

Geng, Tao; Porr, Bernd; Wörgötter, Florentin

2006-05-01

476

Estimating endurance shuttle walk test speed using the six-minute walk test in people with chronic obstructive pulmonary disease.  

PubMed

The objective of this study was to derive and validate an equation to estimate the speed for the endurance shuttle walk test (ESWT) using results from the six-minute walk test (6MWT) in patients with chronic obstructive pulmonary disease (COPD). Participants with diagnosed COPD (n = 84) performed two incremental shuttle walk tests (ISWTs) and two 6MWTs. ESWT speed was calculated from the ISWT results using the original published method. An equation was derived, which directly related six-minute walk distance (6MWD) to ESWT speed. The derived equation was validated in a different group of people with COPD (n = 52). There was a strong correlation between average 6MWD and the calculated ESWT speed (r = 0.88, p < 0.001). The ESWT speed (kilometre per hour) was estimated using the following equation: 0.4889 + (0.0083 × 6MWD). The mean difference (±limits of agreement) between ESWT speeds was calculated using the original published method and found to be 0.03 (±0.77) km/hour. When the ISWT is not the test of choice for clinicians, the 6MWT can be used to accurately estimate the speed for the ESWT. PMID:24659209

Wootton, Sally L; Ng, Cindy; McKeough, Zoe J; Jenkins, Sue; Hill, Kylie; Alison, Jennifer A

2014-05-01

477

Effects of changing speed on knee and ankle joint load during walking and running.  

PubMed

Abstract Joint moments can be used as an indicator of joint loading and have potential application for sports performance and injury prevention. The effects of changing walking and running speeds on joint moments for the different planes of motion still are debatable. Here, we compared knee and ankle moments during walking and running at different speeds. Data were collected from 11 recreational male runners to determine knee and ankle joint moments during different conditions. Conditions include walking at a comfortable speed (self-selected pacing), fast walking (fastest speed possible), slow running (speed corresponding to 30% slower than running) and running (at 4 m · s(-1) ± 10%). A different joint moment pattern was observed between walking and running. We observed a general increase in joint load for sagittal and frontal planes as speed increased, while the effects of speed were not clear in the transverse plane moments. Although differences tend to be more pronounced when gait changed from walking to running, the peak moments, in general, increased when speed increased from comfortable walking to fast walking and from slow running to running mainly in the sagittal and frontal planes. Knee flexion moment was higher in walking than in running due to larger knee extension. Results suggest caution when recommending walking over running in an attempt to reduce knee joint loading. The different effects of speed increments during walking and running should be considered with regard to the prevention of injuries and for rehabilitation purposes. PMID:25105739

de David, Ana Cristina; Carpes, Felipe Pivetta; Stefanyshyn, Darren

2015-02-01

478

Noninteracting multiparticle quantum random walks applied to the graph isomorphism problem for strongly regular graphs  

NASA Astrophysics Data System (ADS)

We investigate the quantum dynamics of particles on graphs (“quantum random walks”), with the aim of developing quantum algorithms for determining if two graphs are isomorphic (related to each other by a relabeling of vertices). We focus on quantum random walks of multiple noninteracting particles on strongly regular graphs (SRGs), a class of graphs with high symmetry that is known to have pairs of graphs that are hard to distinguish. Previous work has already demonstrated analytically that two-particle noninteracting quantum walks cannot distinguish nonisomorphic SRGs of the same family. Here, we demonstrate numerically that three-particle noninteracting quantum walks have significant, but not universal, distinguishing power for pairs of SRGs, proving a fundamental difference between the distinguishing power of two-particle and three-particle noninteracting walks. We show analytically why this distinguishing power is possible, whereas it is forbidden for two-particle noninteracting walks. Based on sampling of SRGs with up to 64 vertices, we find no difference in the distinguishing power of bosonic and fermionic walks. In addition, we find that the four-fermion noninteracting walk has greater distinguishing power than the three-particle walk on SRGs, showing that increasing the particle number increases the distinguishing power. However, we also show analytically that no noninteracting walk with a fixed number of particles can distinguish all SRGs, thus demonstrating a potential fundamental difference in the distinguishing power of interacting versus noninteracting walks.

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

2012-08-01

479

The Effect of Muscle Facilitation Using Kinesio Taping on Walking and Balance of Stroke Patients  

PubMed Central

[Purpose] The aim of this study was to evaluate the changes in function and balance after Kinesio Taping application in stroke patients. [Subjects and Methods] Thirty subjects were randomly divided into an experimental group and control group. The experimental group was applied taping before therapeutic exercise, and the control group received only therapeutic exercise. Functional gait was measured using the straight line walking test, and dynamic balance ability was measured using the Berg Balance Scale. Walking velocity was measured with the 10?m walking test. [Results] There were statistically significant differences between the results of the straight line walking and 10?m walking tests in the pre-post analysis for the experimental group. There were a statistically significant difference in the Berg Balance Scale and 10?m walking test between the two groups. [Conclusion] Application of taping to the paralyzed parts of a stroke patient has a positive effect on improvement of typical asymmetric gait and walking speed. PMID:25435710

Kim, Woo-Il; Choi, Yong-Kyu; Lee, Jung-Ho; Park, Young-Han

2014-01-01

480

The effect of muscle facilitation using kinesio taping on walking and balance of stroke patients.  

PubMed

[Purpose] The aim of this study was to evaluate the changes in function and balance after Kinesio Taping application in stroke patients. [Subjects and Methods] Thirty subjects were randomly divided into an experimental group and control group. The experimental group was applied taping before therapeutic exercise, and the control group received only therapeutic exercise. Functional gait was measured using the straight line walking test, and dynamic balance ability was measured using the Berg Balance Scale. Walking velocity was measured with the 10?m walking test. [Results] There were statistically significant differences between the results of the straight line walking and 10?m walking tests in the pre-post analysis for the experimental group. There were a statistically significant difference in the Berg Balance Scale and 10?m walking test between the two groups. [Conclusion] Application of taping to the paralyzed parts of a stroke patient has a positive effect on improvement of typical asymmetric gait and walking speed. PMID:25435710

Kim, Woo-Il; Choi, Yong-Kyu; Lee, Jung-Ho; Park, Young-Han

2014-11-01

481

Extracting kinematic parameters for monkey bipedal walking from cortical neuronal ensemble activity.  

PubMed

The ability to walk may be critically impacted as the result of neurological injury or disease. While recent advances in brain-machine interfaces (BMIs) have demonstrated the feasibility of upper-limb neuroprostheses, BMIs have not been evaluated as a means to restore walking. Here, we demonstrate that chronic recordings from ensembles of cortical neurons can be used to predict the kinematics of bipedal walking in rhesus macaques - both offline and in real time. Linear decoders extracted 3D coordinates of leg joints and leg muscle electromyograms from the activity of hundreds of cortical neurons. As more complex patterns of walking were produced by varying the gait speed and direction, larger neuronal populations were needed to accurately extract walking patterns. Extraction was further improved using a switching decoder which designated a submodel for each walking paradigm. We propose that BMIs may one day allow severely paralyzed patients to walk again. PMID:19404411

Fitzsimmons, Nathan A; Lebedev, Mikhail A; Peikon, Ian D; Nicolelis, Miguel A L

2009-01-01

482

Kinematics and dynamics analysis of a quadruped walking robot with parallel leg mechanism  

NASA Astrophysics Data System (ADS)

It is desired to require a walking robot for the elderly and the disabled to have large capacity, high stiffness, stability, etc. However, the existing walking robots cannot achieve these requirements because of the weight-payload ratio and simple function. Therefore, Improvement of enhancing capacity and functions of the walking robot is an important research issue. According to walking requirements and combining modularization and reconfigurable ideas, a quadruped/biped reconfigurable walking robot with parallel leg mechanism is proposed. The proposed robot can be used for both a biped and a quadruped walking robot. The kinematics and performance analysis of a 3-UPU parallel mechanism which is the basic leg mechanism of a quadruped walking robot are conducted and the structural parameters are optimized. The results show that performance of the walking robot is optimal when the circumradius R, r of the upper and lower platform of leg mechanism are 161.7 mm, 57.7 mm, respectively. Based on the optimal results, the kinematics and dynamics of the quadruped walking robot in the static walking mode are derived with the application of parallel mechanism and influence coefficient theory, and the optimal coordination distribution of the dynamic load for the quadruped walking robot with over-determinate inputs is analyzed, which solves dynamic load coupling caused by the branches’ constraint of the robot in the walk process. Besides laying a theoretical foundation for development of the prototype, the kinematics and dynamics studies on the quadruped walking robot also boost the theoretical research of the quadruped walking and the practical applications of parallel mechanism.

Wang, Hongbo; Sang, Lingfeng; Hu, Xing; Zhang, Dianfan; Yu, Hongnian

2013-09-01

483

An In-depth Pilot Study on Patterns, Destinations, and Purposes of Walking in Hong Kong Older Adults.  

PubMed

Walking is a suitable activity for older adults and has physical and mental health benefits. To devise interventions that impact levels of walking it is necessary to first understand the purposes for which people walk and the destinations to which they walk. Using a 7-day diary and accelerometry, this study investigated destinations and purposes of walking in older adult residents of an ultra-dense Asian city. Participants reported an average of 17.1 walking trips per week and total weekly accelerometer/diary determined trip walking time averaged 735 min per week; much higher than reported for older adults in non-Asian settings. The most common destinations were within the neighborhood: parks and streets for recreation walking and shops and eating places for transport-related walking. Errands and eating were the most common purposes for transportation trips. The study results can help inform urban design to encourage walking. PMID:24589509

Barnett, Anthony; Cerin, Ester; Cheung, Man-Chin; Chan, Wai-Man

2015-01-01

484

Perceived Effort of Walking: Relationship With Gait, Physical Function and Activity, Fear of Falling, and Confidence in Walking in Older Adults With Mobility Limitations  

PubMed Central

Background Although clinicians have a number of measures to use to describe walking performance, few, if any, of the measures capture a person's perceived effort in walking. Perceived effort of walking may be a factor in what a person does versus what he or she is able to do. Objective The objective of this study was to examine the relationship of perceived effort of walking with gait, function, activity, fear of falling, and confidence in walking in older adults with mobility limitations. Design This investigation was a cross-sectional, descriptive, relational study. Methods The study took place at a clinical research training center. The participants were 50 older adults (mean age=76.8 years, SD=5.5) with mobility limitations. The measurements used were the Rating of Perceived Exertion (RPE) for walking; gait speed; the Modified Gait Abnormality Rating Scale; energy cost of walking; Late Life Function and Disability Instrument (LLFDI) for total, basic, and advanced lower-extremity function and for disability limitations; activity and restriction subscales of the Survey of Activities and Fear of Falling in the Elderly (SAFFE); activity counts; SAFFE fear subscale; and Gait Efficacy Scale (GES). The relationship of the RPE of walking with gait, function, activity, fear, and confidence was determined by using Spearman rank order coefficients and an analysis of variance (adjusted for age and sex) for mean differences between groups defined by no exertion during walking and some exertion during walking. Results The RPE was related to confidence in walking (GES, R=?.326, P=.021) and activity (activity counts, R=.295, P=.044). The RPE groups (no exertion versus some exertion) differed in LLFDI scores for total (57.9 versus 53.2), basic (68.6 versus 61.4), and advanced (49.1 versus 42.6) lower-extremity function; LLFDI scores for disability limitations (74.9 versus 67.5); SAFFE fear subscale scores (0.346 versus 0.643); and GES scores (80.1 versus 67.8) (all P<.05). Limitations The range of RPE scores for the participants studied was narrow. Thus, the real correlations between RPE and gait, physical function, and psychological aspects of walking may be greater than the relationships reported. Conclusions The perceived effort of walking was associated with physical activity and confidence in walking. Reducing the perceived effort of walking may be an important target of interventions to slow the decline in function of older adults with mobility limitations. PMID:22723433

Julius, Leslie M.; Brach, Jennifer S.; Wert, David M.

2012-01-01

485

CHOI AND GRIZZLE, WALKING WITH ANTHROPOMORPHIC FOOT ACTION, SUBMITTED TO IEEE TRAN. ON ROBOTICS, NOVEMBER 7, 2005 1 Planar Bipedal Walking with Anthropomorphic Foot Action  

E-print Network

CHOI AND GRIZZLE, WALKING WITH ANTHROPOMORPHIC FOOT ACTION, SUBMITTED TO IEEE TRAN. ON ROBOTICS, NOVEMBER 7, 2005 1 Planar Bipedal Walking with Anthropomorphic Foot Action Jun Ho Choi, Student Member motion that allows anthropomorphic foot action [3] as depicted in Figure 1. The associated model

Grizzle, Jessy W.

486

Bird Walk Schedule Spring 2013 Arboretum bird walks start this Friday, April 5, and will occur on five Fridays in April and May.  

E-print Network

Bird Walk Schedule ­ Spring 2013 Arboretum bird walks start this Friday, April 5, and will occur on five Fridays in April and May. Friday, April 5 Friday, April 12 Friday, April 19 April 26 - NO BIRD to migrate farther north. By mid-May, the winter birds will be gone and we will be finding warblers, thrushes

Omiecinski, Curtis

487

Spectral Transition for Random Quantum Walks on Trees  

E-print Network

We define and analyze random quantum walks on homogeneous trees of degree $q\\geq 3$. Such walks describe the discrete time evolution of a quantum particle with internal degree of freedom in $\\C^q$ hopping on the neighboring sites of the tree in presence of static disorder. The one time step random unitary evolution operator of the particle depends on a unitary matrix $C\\in U(q)$ which monitors the strength of the disorder. We prove for any $q$ that there exist open sets of matrices in $U(q)$ for which the random evolution has either pure point spectrum almost surely or purely absolutely continuous spectrum, thereby showing the existence of a spectral transition driven by $C\\in U(q)$. For $q\\in\\{3,4\\}$, we establish properties of the spectral diagram which provide a description of the spectral transition.

Eman Hamza; Alain Joye

2012-12-25

488

Two-dimensional random walk in a bounded domain  

NASA Astrophysics Data System (ADS)

In a recent letter Ciftci and Cakmak (EPL, 87 (2009) 60003) showed that the two-dimensional random walk in a bounded domain, where walkers which cross the boundary return to a base curve near the origin with deterministic rules, can produce regular patterns. Our numerical calculations suggest that the cumulative probability distribution function of the returning walkers along the base curve is a Devil's staircase, which can be explained from the mapping of these walks to a non-linear stochastic map. The non-trivial probability distribution function (PDF) is a universal feature of CCRW characterized by the fractal dimension d=1.75(0) of the curve which bounds this distribution.

Basu, Mahashweta; Mohanty, P. K.

2010-06-01

489

Disordered quantum walks in two-dimensional lattices plink  

NASA Astrophysics Data System (ADS)

The properties of the two-dimensional quantum walk with point, line, and circle disorders in phase are reported. Localization is observed in the two-dimensional quantum walk with certain phase disorder and specific initial coin states. We give an explanation of the localization behavior via the localized stationary states of the unitary operator of the walker + coin system and the overlap between the initial state of the whole system and the localized stationary states. Project supported by the National Natural Science Foundation of China (Grant No. 11174052), the National Basic Research Program of China (Grant No. 2011CB921203), and the Open Fund from the State Key Laboratory of Precision Spectroscopy of East China Normal University.

Zhang, Rong; Xu, Yun-Qiu; Xue, Peng

2015-01-01

490

A bioinspired multi-modal flying and walking robot.  

PubMed

With the aim to extend the versatility and adaptability of robots in complex environments, a novel multi-modal flying and walking robot is presented. The robot consists of a flying wing with adaptive morphology that can perform both long distance flight and walking in cluttered environments for local exploration. The robot's design is inspired by the common vampire bat Desmodus rotundus, which can perform aerial and terrestrial locomotion with limited trade-offs. Wings' adaptive morphology allows the robot to modify the shape of its body in order to increase its efficiency during terrestrial locomotion. Furthermore, aerial and terrestrial capabilities are powered by a single locomotor apparatus, therefore it reduces the total complexity and weight of this multi-modal robot. PMID:25599118

Daler, Ludovic; Mintchev, Stefano; Stefanini, Cesare; Floreano, Dario

2015-01-01

491

Random Walk Model on a Hyper-Spherical Lattice  

E-print Network

We use a one-dimensional random walk on $D$-dimensional hyper-spheres to determine the critical behavior of statistical systems in hyper-spherical geometries. First, we demonstrate the properties of such walk by studying the phase diagram of a percolation problem. We find a line of second and first order phase transitions separated by a tricritical point. Then, we analyze the adsorption-desorption transition for a polymer growing near the attractive boundary of a cylindrical cell membrane. We find that the fraction of adsorbed monomers on the boundary vanishes exponentially when the adsorption energy decreases towards its critical value. We observe a crossover phenomenon to an area of linear growth at energies of the order of the inverse cell radius.

S. Boettcher

1994-10-26

492

Extracellular wire tetrode recording in brain of freely walking insects.  

PubMed

Increasing interest in the role of brain activity in insect motor control requires that we be able to monitor neural activity while insects perform natural behavior. We previously developed a technique for implanting tetrode wires into the central complex of cockroach brains that allowed us to record activity from multiple neurons simultaneously while a tethered cockroach turned or altered walking speed. While a major advance, tethered preparations provide access to limited behaviors and often lack feedback processes that occur in freely moving animals. We now present a modified version of that technique that allows us to record from the central complex of freely moving cockroaches as they walk in an arena and deal with barriers by turning, climbing or tunneling. Coupled with high speed video and cluster cutting, we can now relate brain activity to various parameters of the movement of freely behaving insects. PMID:24747699

Guo, Peiyuan; Pollack, Alan J; Varga, Adrienn G; Martin, Joshua P; Ritzmann, Roy E

2014-01-01

493

Degree Distribution in Quantum Walks on Complex Networks  

NASA Astrophysics Data System (ADS)

In this theoretical study, we analyze quantum walks on complex networks, which model network-based processes ranging from quantum computing to biology and even sociology. Specifically, we analytically relate the average long-time probability distribution for the location of a unitary quantum walker to that of a corresponding classical walker. The distribution of the classical walker is proportional to the distribution of degrees, which measures the connectivity of the network nodes and underlies many methods for analyzing classical networks, including website ranking. The quantum distribution becomes exactly equal to the classical distribution when the walk has zero energy, and at higher energies, the difference, the so-called quantumness, is bounded by the energy of the initial state. We give an example for which the quantumness equals a Rényi entropy of the normalized weighted degrees, guiding us to regimes for which the classical degree-dependent result is recovered and others for which quantum effects dominate.

Faccin, Mauro; Johnson, Tomi; Biamonte, Jacob; Kais, Sabre; Migda?, Piotr

2013-10-01

494

Algebraic random walks in the setting of symmetric functions  

E-print Network

Using the standard formulation of algebraic random walks (ARWs) via coalgebras, we consider ARWs for co-and Hopf-algebraic structures in the ring of symmetric functions. These derive from different types of products by dualisation, giving the dual pairs of outer multiplication and outer coproduct, inner multiplication and inner coproduct, and symmetric function plethysm and plethystic coproduct. Adopting standard coordinates for a class of measures (and corresponding distribution functions) to guarantee positivity and correct normalisation, we show the effect of appropriate walker steps of the outer, inner and plethystic ARWs. If the coordinates are interpreted as heights or occupancies of walker(s) at different locations, these walks introduce translations, dilations (scalings) and inflations of the height coordinates, respectively.

Peter D. Jarvis; Demosthenes Ellinas

2012-07-24

495

Limit theorems for discrete-time quantum walks on trees  

E-print Network

We consider a discrete-time quantum walk W_t given by the Grover transformation on the Cayley tree. We reduce W_t to a quantum walk X_t on a half line with a wall at the origin. This paper presents two types of limit theorems for X_t. The first one is X_t as t\\to\\infty, which corresponds to a localization in the case of an initial qubit state. The second one is X_t/t as t\\to\\infty, whose limit density is given by the Konno density function [1-4]. The density appears in various situations of discrete-time cases. The corresponding similar limit theorem was proved in [5] for a continuous-time case on the Cayley tree.

Kota Chisaki; Masatoshi Hamada; Norio Konno; Etsuo Segawa

2009-03-26

496

Quantum walks and quantum search on graphene lattices  

E-print Network

Quantum walks have been very successful in the development of search algorithms in quantum information, in particular in the development of spatial search algorithms. However, the construction of continuous-time quantum search algorithms in two-dimensional lattices has proved difficult, requiring additional degrees of freedom. Here, we demonstrate that continuous-time quantum walk search is possible in two-dimensions by changing the search topology to a graphene lattice, utilising the Dirac point in the energy spectrum. This is made possible by making a change to standard methods of marking a particular site in the lattice. Various ways of marking a site are shown to result in successful search protocols. We further establish that the search can be adapted to transfer probability amplitude across the lattice between specific lattice sites thus establishing a line of communication between these sites.

Iain Foulger; Sven Gnutzmann; Gregor Tanner

2015-01-29

497

Self-Avoiding Walks over Adaptive Triangular Grids  

NASA Technical Reports Server (NTRS)

In this paper, we present a new approach to constructing a "self-avoiding" walk through a triangular mesh. Unlike the popular approach of visiting mesh elements using space-filling curves which is based on a geometric embedding, our approach is combinatorial in the sense that it uses the mesh connectivity only. We present an algorithm for constructing a self-avoiding walk which can be applied to any unstructured triangular mesh. The complexity of the algorithm is O(n x log(n)), where n is the number of triangles in the mesh. We show that for hierarchical adaptive meshes, the algorithm can be easily parallelized by taking advantage of the regularity of the refinement rules. The proposed approach should be very useful in the run-time partitioning and load balancing of adaptive unstructured grids.

Heber, Gerd; Biswas, Rupak; Gao, Guang R.; Saini, Subhash (Technical Monitor)

1998-01-01

498

History dependent quantum random walks as quantum lattice gas automata  

NASA Astrophysics Data System (ADS)

Quantum Random Walks (QRW) were first defined as one-particle sectors of Quantum Lattice Gas Automata (QLGA). Recently, they have been generalized to include history dependence, either on previous coin (internal, i.e., spin or velocity) states or on previous position states. These models have the goal of studying the transition to classicality, or more generally, changes in the performance of quantum walks in algorithmic applications. We show that several history dependent QRW can be identified as one-particle sectors of QLGA. This provides a unifying conceptual framework for these models in which the extra degrees of freedom required to store the history information arise naturally as geometrical degrees of freedom on the lattice.

Shakeel, Asif; Meyer, David A.; Love, Peter J.

2014-12-01

499

Walking on an Oscillating Treadmill: Two Paths to Functional Adaptation  

NASA Technical Reports Server (NTRS)

We mounted a treadmill on top of a six degree-of-freedom motion base platform to investigate and characterize locomotor responses produced by healthy adults when introduced to a novel walking condition. Subjects were classified into two groups according to how their stride times were affected by the perturbation