Symes, Mark D
2009-01-01
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, ...
... get around, and exercise. Having a problem with walking can make daily life more difficult. The pattern ... an abnormal gait and lead to problems with walking. These include: Injuries, diseases, or abnormal development of ...
Butler, B.
1994-12-31
Earth Day, celebrated this April, brought out a spate of press conferences, fairs and media spots. The White House announced its plans to green itself by incorporating energy efficiency and recycling, and Vice President Gore and Energy Secretary O`Leary announced the President`s Executive Order, which mandates the use of energy efficiency in federal facilities with solar as a high-profile option. At the White House itself, however, no solar application has yet been selected for installation. Another Earth Day media spot showed how the nation`s utility companies have joined Secretary O`Leary`s Climate Challenge, an ambitious voluntary program to cut greenhouse-gas emissions. During Earth Day 1994, it became clear how many houses use solar water heating and how often photovoltaics is used to power road signs and sign boards, telephones and repeaters, and for cathodic protection and security lighting. Solar energy is expanding. But if it is to become a truly everyday technology, more institution, governments, businesses and individual consumers are going to have to walk the walk. This means that Earth Day will have to last longer, environmental concerns must become more genuine, and the focus of government and business decisions must be more long-term.
Daniel Reitzner; Daniel Nagaj; Vladimir Buzek
2013-05-15
This tutorial article showcases the many varieties and uses of quantum walks. Discrete time quantum walks are introduced as counterparts of classical random walks. The emphasis is on the connections and differences between the two types of processes (with rather different underlying dynamics) for producing random distributions. We discuss algorithmic applications for graph-searching and compare the two approaches. Next, we look at quantization of Markov chains and show how it can lead to speedups for sampling schemes. Finally, we turn to continuous time quantum walks and their applications, which provide interesting (even exponential) speedups over classical approaches.
V. Zaburdaev; S. Denisov; J. Klafter
2015-01-23
Random walk is a fundamental concept with applications ranging from quantum physics to econometrics. Remarkably, one specific model of random walks appears to be ubiquitous across many fields as a tool to analyze transport phenomena in which the dispersal process is faster than dictated by Brownian diffusion. The L\\'{e}vy walk model combines two key features, the ability to generate anomalously fast diffusion and a finite velocity of a random walker. Recent results in optics, Hamiltonian chaos, cold atom dynamics, bio-physics, and behavioral science demonstrate that this particular type of random walks provides significant insight into complex transport phenomena. This review provides a self-consistent introduction to L\\'{e}vy walks, surveys their existing applications, including latest advances, and outlines further perspectives.
NASA Astrophysics Data System (ADS)
Zaburdaev, V.; Denisov, S.; Klafter, J.
2015-04-01
Random walk is a fundamental concept with applications ranging from quantum physics to econometrics. Remarkably, one specific model of random walks appears to be ubiquitous across many fields as a tool to analyze transport phenomena in which the dispersal process is faster than dictated by Brownian diffusion. The Lévy-walk model combines two key features, the ability to generate anomalously fast diffusion and a finite velocity of a random walker. Recent results in optics, Hamiltonian chaos, cold atom dynamics, biophysics, and behavioral science demonstrate that this particular type of random walk provides significant insight into complex transport phenomena. This review gives a self-consistent introduction to Lévy walks, surveys their existing applications, including latest advances, and outlines further perspectives.
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...
Bates, Jane
2015-09-30
I have come across many walking sticks in my nursing career, but I had never before been hit by one. The stick in question was balanced on its owner's lap as I stood next to her on a crowded bus. PMID:26419150
Quantum random walks without walking
Manouchehri, K.; Wang, J. B.
2009-12-15
Quantum random walks have received much interest due to their nonintuitive dynamics, which may hold the key to a new generation of quantum algorithms. What remains a major challenge is a physical realization that is experimentally viable and not limited to special connectivity criteria. We present a scheme for walking on arbitrarily complex graphs, which can be realized using a variety of quantum systems such as a Bose-Einstein condensate trapped inside an optical lattice. This scheme is particularly elegant since the walker is not required to physically step between the nodes; only flipping coins is sufficient.
Non-classical Random Walks Non-classical Random Walks
Peterson, Jonathon
Non-classical Random Walks Non-classical Random Walks Simple models, surprising results Jonathon Peterson 4/25/2009 1 / 25 #12;Non-classical Random Walks Outline 1 Classical Random Walks Jonathon Peterson 4/25/2009 2 / 25 #12;Non-classical Random Walks Outline 1 Classical Random Walks 2 Random Walks
ERIC Educational Resources Information Center
Willey, David
2010-01-01
This article gives a brief history of fire-walking and then deals with the physics behind fire-walking. The author has performed approximately 50 fire-walks, took the data for the world's hottest fire-walk and was, at one time, a world record holder for the longest fire-walk (www.dwilley.com/HDATLTW/Record_Making_Firewalks.html). He currently…
Relation between Random Walks and Quantum Walks
Stefan Boettcher; Stefan Falkner; Renato Portugal
2015-06-02
Based on studies on four specific networks, we conjecture a general relation between the walk dimensions $d_{w}$ of discrete-time random walks and quantum walks with the (self-inverse) Grover coin. In each case, we find that $d_{w}$ of the quantum walk takes on exactly half the value found for the classical random walk on the same geometry. Since walks on homogeneous lattices satisfy this relation trivially, our results for heterogeneous networks suggests that such a relation holds irrespective of whether translational invariance is maintained or not. To develop our results, we extend the renormalization group analysis (RG) of the stochastic master equation to one with a unitary propagator. As in the classical case, the solution $\\rho(x,t)$ in space and time of this quantum walk equation exhibits a scaling collapse for a variable $x^{d_{w}}/t$ in the weak limit, which defines $d_{w}$ and illuminates fundamental aspects of the walk dynamics, e.g., its mean-square displacement. We confirm the collapse for $\\rho(x,t)$ in each case with extensive numerical simulation. The exact values for $d_{w}$ in themselves demonstrate that RG is a powerful complementary approach to study the asymptotics of quantum walks that weak-limit theorems have not been able to access, such as for systems lacking translational symmetries beyond simple trees.
Gait or Walking Problems the basic facts multiple sclerosis Many people with MS will experience difficulty with walking, which is also called ambulation. The term “gait” refers more specifically to the manner ...
... My Go4Life Get Free Stuff Be a Partner Walking for Your Health Brisk walking is great exercise, and like other endurance exercises , ... you need to do every day. For some, walking for the recommended 30 minutes a day might ...
Kendon, Viv
2014-12-04
Quantum versions of random walks have diverse applications that are motivating experimental implementations as well as theoretical studies. Recent results showing quantum walks are “universal for quantum computation” relate to algorithms, to be run on quantum computers. We consider whether an experimental implementation of a quantum walk could provide useful computation before we have a universal quantum computer.
Walking Wellness. Student Workbook.
ERIC Educational Resources Information Center
Sweetgall, Robert; Neeves, Robert
This comprehensive student text and workbook, for grades four through eight, contains 16 workshop units focusing on walking field trips, aerobic pacing concepts, walking techniques, nutrition, weight control and healthy life-style planning. Co-ordinated homework assignments are included. The appendixes include 10 tips for walking, a calorie chart,…
ERIC Educational Resources Information Center
Mason, Nick
2007-01-01
A generation ago, it was part of growing up for all kids when they biked or walked to school. But in the last 30 years, heavier traffic, wider roads and more dangerous intersections have made it riskier for students walking or pedaling. Today, fewer than 15 percent of kids bike or walk to school compared with more than 50 percent in 1969. In the…
Quantum Random Walk via Classical Random Walk With Internal States
Kovchegov, Yevgeniy
Quantum Random Walk via Classical Random Walk With Internal States Robert M. Burton1, Yevgeniy, OR 97331-4605, USA Abstract. In recent years quantum random walks have garnered much inter- est among efficiently by employing algorithms based on quantum random walks, in the same way that classical random walks
Ernesto Estrada; Jose A. de la Pena; Naomichi Hatano
2013-07-02
Entropies based on walks on graphs and on their line-graphs are defined. They are based on the summation over diagonal and off-diagonal elements of the thermal Green's function of a graph also known as the communicability. The walk entropies are strongly related to the walk regularity of graphs and line-graphs. They are not biased by the graph size and have significantly better correlation with the inverse participation ratio of the eigenmodes of the adjacency matrix than other graph entropies. The temperature dependence of the walk entropies is also discussed. In particular, the walk entropy of graphs is shown to be non-monotonic for regular but non-walk-regular graphs in contrast to non-regular graphs.
Virtually Abelian Quantum Walks
Giacomo Mauro D'Ariano; Marco Erba; Paolo Perinotti; Alessandro Tosini
2015-11-12
We introduce quantum walks on Cayley graphs of non-Abelian groups. We focus on the easiest case of virtually Abelian groups, and introduce a technique to reduce the quantum walk to an equivalent one on an Abelian group with coin system having larger dimension. We apply the technique in the case of two quantum walks on virtually Abelian groups with planar Cayley graphs, finding the exact solution.
... nih.gov/Go4Life Walking Safely in Rural Areas Walking is great exercise and can be particularly enjoyable ... the hustle and bustle of city streets. But walking in rural areas requires special care. Unpaved surfaces ...
Unknown
1914-01-01
This thesis describes the development of a tool to assist animators in doing walk cycles. In traditional animation, animators create expressive walk cycles with key poses. The process of generating walk cycles by hand is tedious and repetitive...
Walking straight into circles.
Souman, Jan L; Frissen, Ilja; Sreenivasa, Manish N; Ernst, Marc O
2009-09-29
Common belief has it that people who get lost in unfamiliar terrain often end up walking in circles. Although uncorroborated by empirical data, this belief has widely permeated popular culture. Here, we tested the ability of humans to walk on a straight course through unfamiliar terrain in two different environments: a large forest area and the Sahara desert. Walking trajectories of several hours were captured via global positioning system, showing that participants repeatedly walked in circles when they could not see the sun. Conversely, when the sun was visible, participants sometimes veered from a straight course but did not walk in circles. We tested various explanations for this walking behavior by assessing the ability of people to maintain a fixed course while blindfolded. Under these conditions, participants walked in often surprisingly small circles (diameter < 20 m), though rarely in a systematic direction. These results rule out a general explanation in terms of biomechanical asymmetries or other general biases [1-6]. Instead, they suggest that veering from a straight course is the result of accumulating noise in the sensorimotor system, which, without an external directional reference to recalibrate the subjective straight ahead, may cause people to walk in circles. PMID:19699093
Skryabin, Dmitry V.; Champneys, Alan R.
2001-06-01
A family of walking solitons is obtained for the degenerate optical parametric oscillator below threshold. The loss-driven mechanism of velocity selection for these structures is described analytically and numerically. Our approach is based on understanding the role played by the field momentum and generic symmetry properties and, therefore, it can be easily generalized to other dissipative multicomponent models with walk off.
NASA Technical Reports Server (NTRS)
Vykukal, H. C.; Chambers, A. B.; Stjohn, R. H. (inventors)
1977-01-01
A walking boot assembly particularly suited for use with a positively pressurized spacesuit is presented. A bootie adapted to be secured to the foot of a wearer, an hermetically sealed boot for receiving the bootie having a walking sole, an inner sole, and an upper portion adapted to be attached to an ankle joint of a spacesuit, are also described.
Marko A. Rodriguez; Jennifer H. Watkins
2015-11-18
A quantum walk places a traverser into a superposition of both graph location and traversal "spin." The walk is defined by an initial condition, an evolution determined by a unitary coin/shift-operator, and a measurement based on the sampling of the probability distribution generated from the quantum wavefunction. Simple quantum walks are studied analytically, but for large graph structures with complex topologies, numerical solutions are typically required. For the quantum theorist, the Gremlin graph traversal machine and language can be used for the numerical analysis of quantum walks on such structures. Additionally, for the graph theorist, the adoption of quantum walk principles can transform what are currently side-effect laden traversals into pure, stateless functional flows. This is true even when the constraints of quantum mechanics are not fully respected (e.g. reversible and unitary evolution). In sum, Gremlin allows both types of theorist to leverage each other's constructs for the advancement of their respective disciplines.
From open quantum walks to unitary quantum walks
Chaobin Liu
2015-02-05
We present an idea to convert to a unitary quantum walk any open quantum walk which is defined on lattices as well as on finite graphs. This approach generalizes to the domain of open quantum walks (or quantum Markov chains) the framework introduced by Szegedy for quantizing Markov chains. For the unitary quantum walks formulated in this article, we define the probability and the mean probability of finding the walk at a node, then derive the asymptotic mean probability.
When Human Walking is a Random Walk
NASA Astrophysics Data System (ADS)
Hausdorff, J. M.
1998-03-01
The complex, hierarchical locomotor system normally does a remarkable job of controlling an inherently unstable, multi-joint system. Nevertheless, the stride interval --- the duration of a gait cycle --- fluctuates from one stride to the next, even under stationary conditions. We used random walk analysis to study the dynamical properties of these fluctuations under normal conditions and how they change with disease and aging. Random walk analysis of the stride-to-stride fluctuations of healthy, young adult men surprisingly reveals a self-similar pattern: fluctuations at one time scale are statistically similar to those at multiple other time scales (Hausdorff et al, J Appl Phsyiol, 1995). To study the stability of this fractal property, we analyzed data obtained from healthy subjects who walked for 1 hour at their usual pace, as well as at slower and faster speeds. The stride interval fluctuations exhibited long-range correlations with power-law decay for up to a thousand strides at all three walking rates. In contrast, during metronomically-paced walking, these long-range correlations disappeared; variations in the stride interval were uncorrelated and non-fractal (Hausdorff et al, J Appl Phsyiol, 1996). To gain insight into the mechanism(s) responsible for this fractal property, we examined the effects of aging and neurological impairment. Using detrended fluctuation analysis (DFA), we computed ?, 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.
ERIC Educational Resources Information Center
Steller, Jenifer J.
This manual presents a schoolwide walking program that includes aerobic fitness information, curriculum integration, and walking tours. "Discover and Understand Carolina Kids by Walking" is D.U.C.K. Walking. An aerobic walking activity, D.U.C.K. Walking has two major goals: (1) to promote regular walking as a way to exercise at any age; and (2) to…
Sable, C.
1987-06-09
This patent describes a pumping unit for reciprocating rod-operated well pumps comprising a motor, a crankshaft driven by the motor, a crank having an end driven from the crankshaft, a samson post having a top, a fixed position horizontal shaft at the top of the samson post, a walking beam having a first end and a second end rockable about a horizontal axis, a first shaft at the first end of the walking beam. It is pivotally coupled to the end of the crank. An operating rod is pivotally coupled to the second end of the walking beam. A hangar arm of predetermined length is suspended from the fixed position horizontal shaft for pivotal movement thereabout. A further horizontal shaft is movable through a circular arc by which the hanger arm is pivotally coupled to the walking beam at a point intermediate its ends.
... nlm.nih.gov/medlineplus/news/fullstory_154789.html Health Tip: Walk Correctly Tips to avoid hurting yourself ... and Physical Fitness Recent Health News Related MedlinePlus Health Topics Exercise and Physical Fitness About MedlinePlus Site ...
Biomechanical analysis of rollator walking
Alkjær, Tine; Larsen, Peter K; Pedersen, Gitte; Nielsen, Linda H; Simonsen, Erik B
2006-01-01
Background The rollator is a very popular walking aid. However, knowledge about how a rollator affects the walking patterns is limited. Thus, the purpose of the study was to investigate the biomechanical effects of walking with and without a rollator on the walking pattern in healthy subjects. Methods The walking pattern during walking with and without rollator was analyzed using a three-dimensional inverse dynamics method. Sagittal joint dynamics and kinematics of the ankle, knee and hip were calculated. In addition, hip joint dynamics and kinematics in the frontal plane were calculated. Seven healthy women participated in the study. Results The hip was more flexed while the knee and ankle joints were less flexed/dorsiflexed during rollator walking. The ROM of the ankle and knee joints was reduced during rollator-walking. Rollator-walking caused a reduction in the knee extensor moment by 50% when compared to normal walking. The ankle plantarflexor and hip abductor moments were smaller when walking with a rollator. In contrast, the angular impulse of the hip extensors was significantly increased during rollator-walking. Conclusion Walking with a rollator unloaded the ankle and especially the knee extensors, increased the hip flexion and thus the contribution of hip extensors to produce movement. Thus, rollator walking did not result in an overall unloading of the muscles and joints of the lower extremities. However, the long-term effect of rollator walking is unknown and further investigation in this field is needed. PMID:16398933
Usherwood, James Richard
2005-09-22
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
Generic Quantum Walks with Memory
Dan Li; Michael Mc Gettrick; Fei Gao; Jie Xu; Qiao-Yan Wen
2015-08-31
Quantum walks with memory are a type of modified quantum walk that records the walker's latest path. In this work, we show that a quantum walk with memory on a digraph can be transformed as a quantum walk without memory on the line digraph of the original one. With this correspondence, we construct a model which includes all possible standard quantum walks with memory on regular graphs. This construction would help us to study quantum walks with memory and also help in corresponding experiments. Based on this model, by taking the straight line as example, we study the general properties of quantum walks with memory, such as variance, occupancy rate and localization. Interestingly, we find that a quantum walk with memory can produce the same probability distribution as that of a standard quantum walk whose initial spin state is $\\sqrt{\\frac{1}{2}}|0\\rangle_p(|1\\rangle_c+i|-1\\rangle_c)$.
Delcomyn, Fred
2004-01-01
With the advent of significant collaborations between researchers who study insect walking and robotics engineers interested in constructing adaptive legged robots, insect walking is once again poised to make a more significant scientific contribution than the numbers of participants in the field might suggest. This review outlines current knowledge of the physiological basis of insect walking with an emphasis on recent new developments in biomechanics and genetic dissection of behavior, and the impact this knowledge is having on robotics. Engineers have begun to team with neurobiologists to build walking robots whose physical design and functional control are based on insect biology. Such an approach may have benefits for engineering, by leading to the construction of better-performing robots, and for biology, by allowing real-time and real-world tests of critical hypotheses about how locomotor control is effected. It is argued that in order for the new field of biorobotics to have significant influence it must adopt criteria for performance and an experimental approach to the development of walking robots. PMID:14651456
Biomechanical conditions of walking
Fan, Y F; Luo, L P; Li, Z Y; Han, S Y; Lv, C S; Zhang, B
2015-01-01
The development of rehabilitation training program for lower limb injury does not usually include gait pattern design. This paper introduced a gait pattern design by using equations (conditions of walking). Following the requirements of reducing force to the injured side to avoid further injury, we developed a lower limb gait pattern to shorten the stride length so as to reduce walking speed, to delay the stance phase of the uninjured side and to reduce step length of the uninjured side. This gait pattern was then verified by the practice of a rehabilitation training of an Achilles tendon rupture patient, whose two-year rehabilitation training (with 24 tests) has proven that this pattern worked as intended. This indicates that rehabilitation training program for lower limb injury can rest on biomechanical conditions of walking based on experimental evidence.
Caceres, Alan Joseph J; Castillo, Juan; Lee, Jinnie; St John, Katherine
2013-01-01
A nearest-neighbor-interchange (NNI)-walk is a sequence of unrooted phylogenetic trees, T1, T2, . . . , T(k) where each consecutive pair of trees differs by a single NNI move. We give tight bounds on the length of the shortest NNI-walks that visit all trees in a subtree-prune-and-regraft (SPR) neighborhood of a given tree. For any unrooted, binary tree, T, on n leaves, the shortest walk takes ?(n²) additional steps more than the number of trees in the SPR neighborhood. This answers Bryant’s Second Combinatorial Challenge from the Phylogenetics Challenges List, the Isaac Newton Institute, 2011, and the Penny Ante Problem List, 2009. PMID:23702562
Reduced Gravity Walking Simulator
NASA Technical Reports Server (NTRS)
1963-01-01
A test subject being suited up for studies on the Reduced Gravity Walking Simulator located in the hangar at Langley Research Center. The initial version of this simulator was located inside the hangar. Later a larger version would be located at the Lunar Landing Facility. This position meant that a person's legs experienced only one sixth of their weight, which was the equivalent of being on the lunar surface. The purpose of this simulator was to study the subject while walking, jumping or running. Researchers conducted studies of various factors such as fatigue limit, energy expenditure, and speed of locomotion.
2007-06-15
The article gives a check list of what one should know before walking a belt conveyor, and what to do during the walk. It then presents a list of what to look at on a walk along the conveyor system (excluding related equipment which could be inspected or maintained during the walk). It gives advice on when to stop the conveyor, on testing the emergency stop system, on recording problems and on acting on things noted. 1 tab.
ERIC Educational Resources Information Center
Bailey, Herb; Kalman, Dan
2011-01-01
Fay and Sam go for a walk. Sam walks along the left side of the street while Fay, who walks faster, starts with Sam but walks to a point on the right side of the street and then returns to meet Sam to complete one segment of their journey. We determine Fay's optimal path minimizing segment length, and thus maximizing the number of times they meet…
Walk Across Texas! Recruitment Brochure
Walk Across Texas! Recruitment Brochure See next page for ordering instructions #12;How to Order Walk Across Texas! Marketing Materials from the Texas A&M AgriLife Extension Bookstore 1. Go to: http where you can order the Walk Across Texas! brochures, bookmark or mini poster FREE. 4. Then, search
Random walks on percolation clusters
Random walks on percolation clusters Ben Hambly Mathematical Insitute University of Oxford Random walks onpercolation clusters Â p. #12;Random motion in random media The study of random media originates how is diffusion affected by the presence of microscopic random irregularities? Random walks
Walk Across Texas walkacrosstexas.tamu.edu Walk Across Texas Packet for Schools
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
10 CFR 431.302 - Definitions concerning walk-in coolers and walk-in freezers.
Code of Federal Regulations, 2010 CFR
2010-01-01
... FOR CERTAIN COMMERCIAL AND INDUSTRIAL EQUIPMENT Walk-in Coolers and Walk-in Freezers § 431.302 Definitions concerning walk-in coolers and walk-in freezers. Walk-in cooler and walk-in freezer mean an... 10 Energy 3 2010-01-01 2010-01-01 false Definitions concerning walk-in coolers and...
ERIC Educational Resources Information Center
Shen, Ji
2009-01-01
In the Walking Out Graphs Lesson described here, students experience several types of representations used to describe motion, including words, sentences, equations, graphs, data tables, and actions. The most important theme of this lesson is that students have to understand the consistency among these representations and form the habit of…
Deterministic Walks with Choice
Beeler, Katy E.; Berenhaut, Kenneth S.; Cooper, Joshua N.; Hunter, Meagan N.; Barr, Peter S.
2014-01-10
This paper studies deterministic movement over toroidal grids, integrating local information, bounded memory and choice at individual nodes. The research is motivated by recent work on deterministic random walks, and applications in multi-agent systems. Several results regarding passing tokens through toroidal grids are discussed, as well as some open questions.
NASA Technical Reports Server (NTRS)
Williams, P.; Sagraniching, E.; Bennett, M.; Singh, R.
1991-01-01
A walking robot was designed, analyzed, and tested as an intelligent, mobile, and a terrain adaptive system. The robot's design was an application of existing technologies. The design of the six legs modified and combines well understood mechanisms and was optimized for performance, flexibility, and simplicity. The body design incorporated two tripods for walking stability and ease of turning. The electrical hardware design used modularity and distributed processing to drive the motors. The software design used feedback to coordinate the system and simple keystrokes to give commands. The walking machine can be easily adapted to hostile environments such as high radiation zones and alien terrain. The primary goal of the leg design was to create a leg capable of supporting a robot's body and electrical hardware while walking or performing desired tasks, namely those required for planetary exploration. The leg designers intent was to study the maximum amount of flexibility and maneuverability achievable by the simplest and lightest leg design. The main constraints for the leg design were leg kinematics, ease of assembly, degrees of freedom, number of motors, overall size, and weight.
ERIC Educational Resources Information Center
Schuster, Dwight
2008-01-01
Physical models in the classroom "cannot be expected to represent the full-scale phenomenon with complete accuracy, not even in the limited set of characteristics being studied" (AAAS 1990). Therefore, by modifying a popular classroom activity called a "planet walk," teachers can explore upper elementary students' current understandings; create an…
ERIC Educational Resources Information Center
Salia, Hannah
2010-01-01
The Walking in My Shoes curriculum at St. Thomas School in Medina, Washington, has been developed to deepen students' understanding of their own heritage and the cultural similarities and differences among their global peers. Exploring the rich diversity of the world's cultural heritage and the interactions of global migrations throughout history,…
Elizabeth Camilleri; Peter P. Rohde; Jason Twamley
2014-01-09
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. Classical self-avoiding random walks have found numerous applications, most notably in the modeling of protein folding. We consider the analogous problem in the quantum setting. 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. We parameterise the strength of the memory recording and the strength of the memory back-action on the walker's motion, and investigate their effect on the dynamics of the walk. We find that by manipulating these parameters 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.
[Walking abnormalities in children].
Segawa, Masaya
2010-11-01
Walking is a spontaneous movement termed locomotion that is promoted by activation of antigravity muscles by serotonergic (5HT) neurons. Development of antigravity activity follows 3 developmental epochs of the sleep-wake (S-W) cycle and is modulated by particular 5HT neurons in each epoch. Activation of antigravity activities occurs in the first epoch (around the age of 3 to 4 months) as restriction of atonia in rapid eye movement (REM) stage and development of circadian S-W cycle. These activities strengthen in the second epoch, with modulation of day-time sleep and induction of crawling around the age of 8 months and induction of walking by 1 year. Around the age of 1 year 6 months, absence of guarded walking and interlimb cordination is observed along with modulation of day-time sleep to once in the afternoon. Bipedal walking in upright position occurs in the third epoch, with development of a biphasic S-W cycle by the age of 4-5 years. Patients with infantile autism (IA), Rett syndrome (RTT), or Tourette syndrome (TS) show failure in the development of the first, second, or third epoch, respectively. Patients with IA fail to develop interlimb coordination; those with RTT, crawling and walking; and those with TS, walking in upright posture. Basic pathophysiology underlying these condition is failure in restricting atonia in REM stage; this induces dysfunction of the pedunculopontine nucleus and consequently dys- or hypofunction of the dopamine (DA) neurons. DA hypofunction in the developing brain, associated with compensatory upward regulation of the DA receptors causes psychobehavioral disorders in infancy (IA), failure in synaptogenesis in the frontal cortex and functional development of the motor and associate cortexes in late infancy through the basal ganglia (RTT), and failure in functional development of the prefrontal cortex through the basal ganglia (TS). Further, locomotion failure in early childhood causes failure in development of functional specialization of the cortex through the spinal stepping generator-fastigial nucleus-thalamus-cortex pathway. Early detection of locomotion failure and early adjustment of this condition through environmental factors can prevent the development of higher cortical dysfunction. PMID:21068458
Devismes, StÃ©phane
Introduction Random Walks Random Walks with Tabu Lists In Messages In Nodes Experimental Results Conclusion Routing Algorithms using Random Walks with Tabu Lists Karine Altisen, StÃ©phane Devismes, Pascal;Introduction Random Walks Random Walks with Tabu Lists In Messages In Nodes Experimental Results Conclusion
Relativistic Weierstrass random walks
NASA Astrophysics Data System (ADS)
Saa, Alberto; Venegeroles, Roberto
2010-08-01
The Weierstrass random walk is a paradigmatic Markov chain giving rise to a Lévy-type superdiffusive behavior. It is well known that special relativity prevents the arbitrarily high velocities necessary to establish a superdiffusive behavior in any process occurring in Minkowski spacetime, implying, in particular, that any relativistic Markov chain describing spacetime phenomena must be essentially Gaussian. Here, we introduce a simple relativistic extension of the Weierstrass random walk and show that there must exist a transition time tc delimiting two qualitative distinct dynamical regimes: the (nonrelativistic) superdiffusive Lévy flights, for t
Relativistic Weierstrass random walks.
Saa, Alberto; Venegeroles, Roberto
2010-08-01
The Weierstrass random walk is a paradigmatic Markov chain giving rise to a Lévy-type superdiffusive behavior. It is well known that special relativity prevents the arbitrarily high velocities necessary to establish a superdiffusive behavior in any process occurring in Minkowski spacetime, implying, in particular, that any relativistic Markov chain describing spacetime phenomena must be essentially Gaussian. Here, we introduce a simple relativistic extension of the Weierstrass random walk and show that there must exist a transition time t{c} delimiting two qualitative distinct dynamical regimes: the (nonrelativistic) superdiffusive Lévy flights, for t
Mads T. Frandsen
2007-10-23
I report on our construction and analysis of the effective low energy Lagrangian for the Minimal Walking Technicolor (MWT) model. The parameters of the effective Lagrangian are constrained by imposing modified Weinberg sum rules and by imposing a value for the S parameter estimated from the underlying Technicolor theory. The constrained effective Lagrangian allows for an inverted vector vs. axial-vector mass spectrum in a large part of the parameter space.
Thank you for your interest in Walk Across Texas! Walk Across Texas! is an eight-week walking program for teams of eight people. Participants walk for eight weeks in teams of eight (members do not need to walk togetherCbut you can if you want to). One member needs to be the team captain. Members
Quantum stochastic walks: A generalization of classical random walks and quantum walks
Whitfield, James D.; Rodriguez-Rosario, Cesar A.; Aspuru-Guzik, Alan
2010-02-15
We introduce the quantum stochastic walk (QSW), which determines the evolution of a generalized quantum-mechanical walk on a graph that obeys a quantum stochastic equation of motion. Using an axiomatic approach, we specify the rules for all possible quantum, classical, and quantum-stochastic transitions from a vertex as defined by its connectivity. We show how the family of possible QSWs encompasses both the classical random walk (CRW) and the quantum walk (QW) as special cases but also includes more general probability distributions. As an example, we study the QSW on a line and the glued tree of depth three to observe the behavior of the QW-to-CRW transition.
Quantum stochastic walks: A generalization of classical random walks and quantum walks
Rodriguez-Rosario, Cesar A.; Aspuru-Guzik, Alan; Whitfield, James D.
2010-02-23
We introduce the quantum stochastic walk (QSW), which determines the evolution of a generalized quantum-mechanical walk on a graph that obeys a quantum stochastic equation of motion. Using an axiomatic approach, we specify the rules for all possible quantum, classical, and quantum-stochastic transitions from a vertex as defined by its connectivity. We show how the family of possible QSWs encompasses both the classical random walk (CRW) and the quantum walk (QW) as special cases but also includes more general probability distributions. As an example, we study the QSW on a line and the glued tree of depth three to observe the behavior of the QW-to-CRW transition.
NASA Technical Reports Server (NTRS)
Larimer, Stanley J.; Lisec, Thomas R.; Spiessbach, Andrew J.
1990-01-01
Proposed walking-beam robot simpler and more rugged than articulated-leg walkers. Requires less data processing, and uses power more efficiently. Includes pair of tripods, one nested in other. Inner tripod holds power supplies, communication equipment, computers, instrumentation, sampling arms, and articulated sensor turrets. Outer tripod holds mast on which antennas for communication with remote control site and video cameras for viewing local and distant terrain mounted. Propels itself by raising, translating, and lowering tripods in alternation. Steers itself by rotating raised tripod on turntable.
NASA Technical Reports Server (NTRS)
Larimer, Stanley J.; Lisec, Thomas R.; Spiessbach, Andrew J.; Waldron, Kenneth J.
1990-01-01
Proposed agile walking robot operates over rocky, sandy, and sloping terrain. Offers stability and climbing ability superior to other conceptual mobile robots. Equipped with six articulated legs like those of insect, continually feels ground under leg before applying weight to it. If leg sensed unexpected object or failed to make contact with ground at expected point, seeks alternative position within radius of 20 cm. Failing that, robot halts, examines area around foot in detail with laser ranging imager, and replans entire cycle of steps for all legs before proceeding.
University of Sussex boundary walk
Sussex, University of
of Life Sciences. You also cross the road to the Sports Pavilion. At the southern end of the tree beltUniversity of Sussex boundary walk Front Belt, Badgers and the Pelham Wall The walk starts at Knights Gate Road at the main entrance to the University of Sussex. You then proceed due west down some
Mak, Chi H.; Pham, Phuong; Afif, Samir A.; Goodman, Myron F.
2015-01-01
Enzymes that rely on random walk to search for substrate targets in a heterogeneously dispersed medium can leave behind complex spatial profiles of their catalyzed conversions. The catalytic signatures of these random-walk enzymes are the result of two coupled stochastic processes: scanning and catalysis. Here we develop analytical models to understand the conversion profiles produced by these enzymes, comparing an intrusive model, in which scanning and catalysis are tightly coupled, against a loosely coupled passive model. Diagrammatic theory and path-integral solutions of these models revealed clearly distinct predictions. Comparison to experimental data from catalyzed deaminations deposited on single-stranded DNA by the enzyme activation-induced deoxycytidine deaminase (AID) demonstrates that catalysis and diffusion are strongly intertwined, where the chemical conversions give rise to new stochastic trajectories that were absent if the substrate DNA was homogeneous. The C ? U deamination profiles in both analytical predictions and experiments exhibit a strong contextual dependence, where the conversion rate of each target site is strongly contingent on the identities of other surrounding targets, with the intrusive model showing an excellent fit to the data. These methods can be applied to deduce sequence-dependent catalytic signatures of other DNA modification enzymes, with potential applications to cancer, gene regulation, and epigenetics. PMID:26465508
NASA Astrophysics Data System (ADS)
Mak, Chi H.; Pham, Phuong; Afif, Samir A.; Goodman, Myron F.
2015-09-01
Enzymes that rely on random walk to search for substrate targets in a heterogeneously dispersed medium can leave behind complex spatial profiles of their catalyzed conversions. The catalytic signatures of these random-walk enzymes are the result of two coupled stochastic processes: scanning and catalysis. Here we develop analytical models to understand the conversion profiles produced by these enzymes, comparing an intrusive model, in which scanning and catalysis are tightly coupled, against a loosely coupled passive model. Diagrammatic theory and path-integral solutions of these models revealed clearly distinct predictions. Comparison to experimental data from catalyzed deaminations deposited on single-stranded DNA by the enzyme activation-induced deoxycytidine deaminase (AID) demonstrates that catalysis and diffusion are strongly intertwined, where the chemical conversions give rise to new stochastic trajectories that were absent if the substrate DNA was homogeneous. The C ?U deamination profiles in both analytical predictions and experiments exhibit a strong contextual dependence, where the conversion rate of each target site is strongly contingent on the identities of other surrounding targets, with the intrusive model showing an excellent fit to the data. These methods can be applied to deduce sequence-dependent catalytic signatures of other DNA modification enzymes, with potential applications to cancer, gene regulation, and epigenetics.
Walking indoors, walking outdoors: an fMRI study
Dalla Volta, Riccardo; Fasano, Fabrizio; Cerasa, Antonio; Mangone, Graziella; Quattrone, Aldo; Buccino, Giovanni
2015-01-01
An observation/execution matching system for walking has not been assessed yet. The present fMRI study was aimed at assessing whether, as for object-directed actions, an observation/execution matching system is active for walking and whether the spatial context of walking (open or narrow space) recruits different neural correlates. Two experimental conditions were employed. In the execution condition, while being scanned, participants performed walking on a rolling cylinder located just outside the scanner. The same action was performed also while observing a video presenting either an open space (a country field) or a narrow space (a corridor). In the observation condition, participants observed a video presenting an individual walking on the same cylinder on which the actual action was executed, the open space video and the narrow space video, respectively. Results showed common bilateral activations in the dorsal premotor/supplementary motor areas and in the posterior parietal lobe for both execution and observation of walking, thus supporting a matching system for this action. Moreover, specific sectors of the occipital–temporal cortex and the middle temporal gyrus were consistently active when processing a narrow space versus an open one, thus suggesting their involvement in the visuo-motor transformation required when walking in a narrow space. We forward that the present findings may have implications for rehabilitation of gait and sport training. PMID:26483745
Erdmenger, Johanna; Halter, Sebastian; Núñez, Carlos; Tasinato, Gianmassimo E-mail: s.halter@physik.uni-muenchen.de E-mail: gianmassimo.tasinato@port.ac.uk
2013-01-01
We propose a new model of slow-roll inflation in string cosmology, based on warped throat supergravity solutions displaying 'walking' dynamics, i.e. the coupling constant of the dual gauge theory slowly varies over a range of energy scales. The features of the throat geometry are sourced by a rich field content, given by the dilaton and RR and NS fluxes. By considering the motion of a D3-brane probe in this geometry, we are able to analytically calculate the brane potential in a physically interesting regime. This potential has an inflection point: in its proximity we realize a model of inflation lasting sixty e-foldings, and whose robust predictions are in agreement with current observations. We are also able to interpret some of the most interesting aspects of this scenario in terms of the properties of the QFT dual theory.
Reduced Gravity Walking Simulator
NASA Technical Reports Server (NTRS)
1963-01-01
A test subject being suited up for studies on the Reduced Gravity Walking Simulator located in the hanger at Langley Research Center. The initial version of this simulator was located inside the hanger. Later a larger version would be located at the Lunar Landing Facility. The purpose of this simulator was to study the subject while walking, jumping or running. Researchers conducted studies of various factors such as fatigue limit, energy expenditure, and speed of locomotion. Francis B. Smith wrote in his paper 'Simulators For Manned Space Research,' 'I would like to conclude this talk with a discussion of a device for simulating lunar gravity which is very effective and yet which is so simple that its cost is in the order of a few thousand dollars at most, rather than hundreds of thousands. With a little ingenuity, one could almost build this type simulator in his backyard for children to play on. The principle is ...if a test subject is suspended in a sling so that his body axis makes an angle of 9 1/2 degrees with the horizontal and if he then 'stands' on a platform perpendicular to his body axis, the component of the earth's gravity forcing him toward the platform is one times the sine of 9 1/2 degrees or approximately 1/6 of the earth's normal gravity field. That is, a 180 pound astronaut 'standing' on the platform would exert a force of only 30 pounds - the same as if he were standing upright on the lunar surface.' Published in James R. Hansen, Spaceflight Revolution: NASA Langley Research Center From Sputnik to Apollo, NASA SP-4308; Francis B. Smith, 'Simulators For Manned Space Research,' Paper for 1966 IEEE International Convention, New York, NY, March 21-25, 1966.
Pratt, Gill Andrews
2002-02-01
For both historical and technological reasons, most robots, including those meant to mimic animals or operate in natural environments,3 use actuators and control systems that have high (stiff) mechanical impedance. By contrast, most animals exhibit low (soft) impedance. While a robot's stiff joints may be programmed to closely imitate the recorded motion of an animal's soft joints, any unexpected position disturbances will generate reactive forces and torques much higher for the robot than for the animal. The dual of this is also true: while an animal will react to a force disturbance by significantly yielding position, a typical robot will greatly resist.These differences cause three deleterious effects for high impedance robots. First, the higher forces may cause damage to the robot or to its environment (which is particularly important if that environment includes people). Second, the robot must acquire very precise information about its position relative to the environment so as to minimize its velocity upon impact. Third, many of the self-stabilizing effects of natural dynamics are "shorted out"4 by the robot's high impedance, so that stabilization requires more effort from the control system.Over the past 5 yr, our laboratory has designed a series of walking robots based on "Series-Elastic Actuators" and "Virtual Model Control." Using these two techniques, we have been able to build low-impedance walking robots that are both safe and robust, that operate blindly without any model of upcoming terrain, and that add minimal control effort in parallel to their self-stabilizing passive dynamics. We have discovered that it is possible to achieve surprisingly effective ambulation from rather simple mechanisms and control systems. After describing the historical and technological motivations for our approach, this paper gives an overview of our methods and shows some of the results we have obtained. PMID:21708707
10 CFR 431.302 - Definitions concerning walk-in coolers and walk-in freezers.
Code of Federal Regulations, 2013 CFR
2013-01-01
... 10 Energy 3 2013-01-01 2013-01-01 false Definitions concerning walk-in coolers and walk-in freezers. 431.302 Section 431.302 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION ENERGY EFFICIENCY PROGRAM FOR CERTAIN COMMERCIAL AND INDUSTRIAL EQUIPMENT Walk-in Coolers and Walk-in Freezers § 431.302 Definitions concerning walk-in coolers and...
Constraining Walking and Custodial Technicolor
Roshan Foadi; Mads T. Frandsen; Francesco Sannino
2007-12-12
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.
Constraining walking and custodial technicolor
Foadi, Roshan; Frandsen, Mads T.; Sannino, Francesco
2008-05-01
We show how to constrain the physical spectrum of walking technicolor models via precision measurements and modified Weinberg sum rules. We also study models possessing a custodial symmetry for the S parameter at the effective Lagrangian level - custodial technicolor - and argue that these models cannot emerge from walking-type dynamics. We suggest that it is possible to have a very light spin-one axial (vector) boson. However, in the walking dynamics the associated vector boson is heavy while it is degenerate with the axial in custodial technicolor.
Rosmanis, Ansis
2010-01-01
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 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
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.
NASA Astrophysics Data System (ADS)
Rosmanis, Ansis
2011-02-01
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
2011-02-15
I introduce a continuous-time quantum walk on graphs called the quantum snake walk, the basis states of which are fixed-length paths (snakes) in the underlying graph. First, I analyze the quantum snake walk on the line, and I show that, even though most states stay localized throughout the evolution, there are specific states that most likely move on the line as wave packets with momentum inversely proportional to the length of the snake. Next, I discuss how an algorithm based on the quantum snake walk might potentially be able to solve an extended version of the glued trees problem, which asks to find a path connecting both roots of the glued trees graph. To the best of my knowledge, no efficient quantum algorithm solving this problem is known yet.
Walking Dynamics from String Duals
Carlos Nunez; Ioannis Papadimitriou; Maurizio Piai
2009-01-13
Within the context of a String Theory dual to N=1 gauge theories with gauge group SU(Nc) and large Nc, we identify a class of solutions of the background equations for which a suitably defined dual of the gauge coupling exhibits the features of a walking theory. We find evidence for three distinct, dynamically generated scales, characterizing walking, symmetry breaking and confinement, and we put them in correspondence with field theory by an analysis of the operators driving the flow.
Walking Behavior in Technicolored GUTs
A. Doff
2009-02-19
There exist two ways to obtain walk behavior: assuming a large number of technifermions in the fundamental representation of the technicolor (TC) gauge group, or a small number of technifermions, assuming that these fermions are in higher-dimensional representations of the TC group. We propose a scheme to obtain the walking behavior based on technicolored GUTs (TGUTs), where elementary scalars with the TC degree of freedom may remain in the theory after the GUT symmetry breaking.
Belyaev, Alexander; Foadi, Roshan; Frandsen, Mads T.; Jaervinen, Matti; Sannino, Francesco; Pukhov, Alexander
2009-02-01
We analyze the potential of the Large Hadron Collider (LHC) to observe signatures of phenomenologically viable walking technicolor models. We study and compare the Drell-Yan and vector boson fusion mechanisms for the production of composite heavy vectors. We find that the heavy vectors are most easily produced and detected via the Drell-Yan processes. The composite Higgs phenomenology is also studied. If technicolor walks at the LHC, its footprints will be visible and our analysis will help in uncovering them.
10 CFR 431.302 - Definitions concerning walk-in coolers and walk-in freezers.
Code of Federal Regulations, 2012 CFR
2012-01-01
... cooler or walk-in freezer that are not part of its refrigeration system. K-factor means the thermal conductivity of a material. Manufacturer of a walk-in cooler or walk-in freezer means any person who:...
10 CFR 431.302 - Definitions concerning walk-in coolers and walk-in freezers.
Code of Federal Regulations, 2014 CFR
2014-01-01
... cooler or walk-in freezer that are not part of its refrigeration system. K-factor means the thermal conductivity of a material. Manufacturer of a walk-in cooler or walk-in freezer means any person who:...
Portable walking beam pump jack
Laney, R.N.
1986-02-25
This patent describes a portable walking beam pump jack for use in pumping liquids from an oil well. This jack consists of: an elongated frame having a longitudinal axis and front and rear ends, the frame also including first and second support seats; a towing receptacle, an axle connected transversely across the frame; ground engaging wheels connected to the axle for supporting the frame for rolling transportation; stabilizing means for securing the frame with respect to a ground location; a walking beam having a first end, a midportion and a second end, the second end being adapted for connection to a pumping rod; an engine mounted on the frame; a pair of arms counterweighted for balancing a pumping rod connected to the walking beam, a drive yoke, a support assembly foldably mounted on the frame and upon which the midportion of the walking beam is pivotally connected, the support assembly the arms and the drive yoke being foldable together, from a first, fixed position in which the walking beam arms and yoke are supported in a raised position for rocking in a pumping motion to a second, fixed position disposed downwardly and forwardly from the first fixed position and in which the walking beam arms and yoke are held in a lowered position for transportation; a front support and a hydraulic cylinder connected between the frame and the support assembly for moving the support assembly between the first, fixed position and the second fixed position.
Quantum walks based on an interferometric analogy
NASA Astrophysics Data System (ADS)
Hillery, Mark; Bergou, Janos; Feldman, Edgar
2003-09-01
There are presently two models for quantum walks on graphs. The “coined” walk uses discrete-time steps, and contains, besides the particle making the walk, a second quantum system, the coin, that determines the direction in which the particle will move. The continuous walk operates with continuous time. Here a third model for quantum walks is proposed, which is based on an analogy to optical interferometers. It is a discrete-time model, and the unitary operator that advances the walk one step depends only on the local structure of the graph on which the walk is taking place. This type of walk also allows us to introduce elements, such as phase shifters, that have no counterpart in classical random walks. Several examples are discussed.
Persistent personal biases in walking.
Boeddeker, Norbert; Jetzschke, Simon; Ernst, Marc
2015-09-01
Locomotion along a given path in the absence of vision and audition is known to be inaccurate. Here we ask about the nature of these inaccuracies. To this end, we analyzed the performance of participants in three walking experiments involving straight and angle-walking tasks. In the first experiment eight blindfolded participants were guided along paths of different lengths and asked to turn to a target location by an angle of ±90° in a sports hall (size: 25x45m). We found significant biases in turn angles, i.e. systematic deviations from the correct angle that were characteristic of certain participants, whereas varying path length had weak effects on turn accuracy and precision. To check whether this idiosyncrasy was persistent over time and present in another type of walking task, we performed a second experiment several weeks after the first. Here, the same participants were guided to walk turns with varying amplitude. We then asked them to judge whether they had walked an angle larger or smaller than 90° in a two-alternative forced-choice (2AFC) paradigm. Very surprisingly, the personal bias was highly correlated between the two experiments indicating that the sense of direction can be persistently and individually biased in the absence of external directional cues. In a third experiment the participants where asked to walk straight on slanted and level surfaces. Here, we again found persistent directional biases in most participants. The direction of surface inclination did not significantly influence these individual biases. We found systematic angular biases in several walking tasks that were persistent over weeks. The biases reported here for healthy participants are most likely counterbalanced during normal daily-life by using visual and auditory cues for spatial orientation. Meeting abstract presented at VSS 2015. PMID:26327013
Correlated Markov Quantum Walks
Eman Hamza; Alain Joye
2011-10-21
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.
Effects of Nordic walking and walking on spatiotemporal gait parameters and ground reaction force
Park, Seung Kyu; Yang, Dae Jung; Kang, Yang Hun; Kim, Je Ho; Uhm, Yo Han; Lee, Yong Seon
2015-01-01
[Purpose] The purpose of this study was to investigate the effects of Nordic walking and walking on spatiotemporal gait parameters and ground reaction force. [Subjects] The subjects of this study were 30 young adult males, who were divided into a Nordic walking group of 15 subjects and a walking group of 15 subjects. [Methods] To analyze the spatiotemporal parameters and ground reaction force during walking in the two groups, the six-camera Vicon MX motion analysis system was used. The subjects were asked to walk 12 meters using the more comfortable walking method for them between Nordic walking and walking. After they walked 12 meters more than 10 times, their most natural walking patterns were chosen three times and analyzed. To determine the pole for Nordic walking, each subject’s height was multiplied by 0.68. We then measured the spatiotemporal gait parameters and ground reaction force. [Results] Compared with the walking group, the Nordic walking group showed an increase in cadence, stride length, and step length, and a decrease in stride time, step time, and vertical ground reaction force. [Conclusion] The results of this study indicate that Nordic walking increases the stride and can be considered as helping patients with diseases affecting their gait. This demonstrates that Nordic walking is more effective in improving functional capabilities by promoting effective energy use and reducing the lower limb load, because the weight of the upper and lower limbs is dispersed during Nordic walking. PMID:26504319
Walking on ballast impacts balance.
Wade, Chip; Garner, John C; Redfern, Mark S; Andres, Robert O
2014-01-01
Railroad workers often perform daily work activities on irregular surfaces, specifically on ballast rock. Previous research and injury epidemiology have suggested a relationship between working on irregular surfaces and postural instability. The purpose of this study was to examine the impact of walking on ballast for an extended duration on standing balance. A total of 16 healthy adult males walked on a 7.62 m × 4.57 m (25 ft × 15 ft) walking surface of no ballast (NB) or covered with ballast (B) of an average rock size of about 1 inch for 4 h. Balance was evaluated using dynamic posturography with the NeuroCom(®) Equitest System(™) prior to experiencing the NB or B surface and again every 30 min during the 4 h of ballast exposure. Dependent variables were the sway velocity and root-mean-square (RMS) sway components in the medial-lateral and anterior-posterior directions. Repeated measures ANOVA revealed statistically significant differences in RMS and sway velocity between ballast surface conditions and across exposure times. Overall, the ballast surface condition induced greater sway in all of the dynamic posturography conditions. Walking on irregular surfaces for extended durations has a deleterious effect on balance compared to walking on a surface without ballast. These findings of changes in balance during ballast exposure suggest that working on an irregular surface may impact postural control. PMID:24354716
Whistle … and Walk … While You Work
... fullstory_155058.html Whistle ? and Walk ? While You Work Small study found a short stroll restored blood ... have to sit almost all day while you work, take a short walk whenever you can. Why? ...
Dissipative quantum computing with open quantum walks
Sinayskiy, Ilya; Petruccione, Francesco
2014-12-04
An open quantum walk approach to the implementation of a dissipative quantum computing scheme is presented. The formalism is demonstrated for the example of an open quantum walk implementation of a 3 qubit quantum circuit consisting of 10 gates.
Quantum Walk Search through Potential Barriers
Thomas G. Wong
2015-09-24
A randomly walking quantum particle searches for a marked vertex on the complete graph of $N$ vertices in Grover's $\\Theta(\\sqrt{N})$ steps, which is quadratically faster than a classical random walk's $\\Theta(N)$ steps. The basis of this speedup and the success of other quantum walk algorithms is often attributed to the quantum walk's ballistic propagation, which is quadratically faster than a classical random walk's diffusion. We show that this faster propagation is not the whole story, however. If sufficiently strong potential barriers hinder the quantum walk, it can lose its quantum speedup despite retaining ballistic dispersion. Thus ballistic spreading alone does not yield fast quantum walk algorithms. Closer inspection reveals that quantum walks search quickly by applying just the right phases for amplitude amplification to succeed.
On Convergent Probability of a Random Walk
ERIC Educational Resources Information Center
Lee, Y.-F.; Ching, W.-K.
2006-01-01
This note introduces an interesting random walk on a straight path with cards of random numbers. The method of recurrent relations is used to obtain the convergent probability of the random walk with different initial positions.
A Walking School Bus Program Increased Students' Walking to School and Decreased Transport by Car
Technology Transfer Automated Retrieval System (TEKTRAN)
Walking school buses are popular programs designed to overcome barriers and increase the numbers of children who walk to school. We tested the hypothesis that a walking school bus program would increase the proportion of children walking to school and decrease the proportion transported to school by...
Walking > Walking-in-Place > Flying, in Virtual Environments Martin Usoh
Slater, Mel
Walking > Walking-in-Place > Flying, in Virtual Environments Martin Usoh Kevin Arthur Mary C environment experience a higher subjective sense of presence when they locomote by walking-in-place (virtual walking) than when they push-button-fly (along the floor plane). We replicated their study, adding real
The effect of walking speed and avatars on Redirected Walking Master Thesis
The effect of walking speed and avatars on Redirected Walking Master Thesis Fakultät Informatik in combination with Redirected Walking 11 1.1.5 Studying human behavior while walking 11 1.1.6 Avatars in virtual 48 4.2 Concepts: Extending redirection with avatar distractors 49 4.2.1 Support of existing
Foot placement in a body reference frame during walking and its relationship to hemiparetic walking Keywords: Walking Biomechanics Foot placement Stroke Spatiotemporal parameters a b s t r a c t Background: Foot placement during walking is closely linked to the body position, yet it is typically quantified
KidsWalk-to-School: A Guide To Promote Walking to School.
ERIC Educational Resources Information Center
Center for Chronic Disease Prevention and Health Promotion (DHHS/CDC), Atlanta, GA.
This guide encourages people to create safe walking and biking routes to school, promoting four issues: physically active travel, safe and walkable routes to school, crime prevention, and health environments. The chapters include: "KidsWalk-to-School: A Guide to Promote Walking to School" (Is there a solution? Why is walking to school important?…
The Recovery of Walking in Stroke Patients: A Review
ERIC Educational Resources Information Center
Jang, Sung Ho
2010-01-01
We reviewed the literature on walking recovery of stroke patients as it relates to the following subjects: epidemiology of walking dysfunction, recovery course of walking, and recovery mechanism of walking (neural control of normal walking, the evaluation methods for leg motor function, and motor recovery mechanism of leg). The recovery of walking…
After Talking the Talk, Now Walk the Walk
ERIC Educational Resources Information Center
Vukovic, Paul
2011-01-01
In this article, the author describes what his students are doing following the ATM Easter conference in Telford, where he was inspired by a workshop entitled "Vitamin D Maths," conducted by Jocelyn D'Arcy. He describes an activity that allows his Year 11 students to walk through angles drawn on the floors. This topic will now literally be given a…
Generalized Open Quantum Walks on Apollonian Networks
Pawela, ?ukasz; Gawron, Piotr; Miszczak, Jaros?aw Adam; Sadowski, Przemys?aw
2015-01-01
We introduce the model of generalized open quantum walks on networks using the Transition Operation Matrices formalism. We focus our analysis on the mean first passage time and the average return time in Apollonian networks. These results differ significantly from a classical walk on these networks. We show a comparison of the classical and quantum behaviour of walks on these networks. PMID:26177452
Realistic Human Walking Paths David C. Brogan
Brogan, David
Realistic Human Walking Paths David C. Brogan Department of Computer Science University of Virginia are influenced by kinematic and dynami- cal constraints. A realistic model of human walking paths is an important natural human behavior than previous models. 1. Introduction Realistic walking animations are required
Developmental Continuity? Crawling, Cruising, and Walking
ERIC Educational Resources Information Center
Adolph, Karen E.; Berger, Sarah E.; Leo, Andrew J.
2011-01-01
This research examined developmental continuity between "cruising" (moving sideways holding onto furniture for support) and walking. Because cruising and walking involve locomotion in an upright posture, researchers have assumed that cruising is functionally related to walking. Study 1 showed that most infants crawl and cruise concurrently prior…
Walking cavity solitons Dmitry V. Skryabin1
Skryabin, Dmitry
Walking cavity solitons Dmitry V. Skryabin1 and Alan R. Champneys2 1 Department of Physics manuscript received 20 February 2001; published 24 May 2001 A family of walking solitons is obtained dissipative multicomponent models with walk off. DOI: 10.1103/PhysRevE.63.066610 PACS number s : 42.65.Tg, 42
Diss. ETH No 13748 WALKING GAIT CONTROL
Still, Susanna
Diss. ETH No 13748 WALKING GAIT CONTROL FOR FOUR-LEGGED ROBOTS Bio-inspired technology analyzed for the inter-leg coordination of four-legged walking machines. The controller is implemented using Very Large Scale Integrated (VLSI) technology. It is able to generate walking behaviors for a four-legged machine
RANDOM WALK IN DETERMINISTICALLY CHANGING ENVIRONMENT
Liverani, Carlangelo
RANDOM WALK IN DETERMINISTICALLY CHANGING ENVIRONMENT DMITRY DOLGOPYAT AND CARLANGELO LIVERANI Abstract. We consider a random walk with transition probabilities weakly dependent on an environment of the environment the walk satisfies the CLT. 1. Introduction The continuing interest in the limit properties
Walk Across Texas! and Texas Education Agency
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
Markov Random Walk Representations with Continuous Distributions
Yeang, Chen-Hsiang
Markov Random Walk Representations with Continuous Distributions Chen-Hsiang Yeang MIT Artificial Cambridge, UK Abstract We propose a framework to extend Markov random walks (Szummer and Jaakkola, 2001 distinct ex- amples are geodesic distances (Tenenbaum, 1998) and Markov random walks (Szummer & Jaakkola
WW Scattering in Walking Technicolor
Roshan Foadi; Francesco Sannino
2008-01-04
We analyze the WW scattering in scenarios of dynamical electroweak symmetry breaking of walking technicolor type. We show that in these theories there are regions of the parameters space allowed by the electroweak precision data, in which unitarity violation is delayed at tree level up to around 3-4 TeV without the inclusion of any sub-TeV resonances.
Walk around the Block Curriculum.
ERIC Educational Resources Information Center
Center for Understanding the Built Environment, Prairie Village, KS.
This curriculum packet contains two teacher-developed lesson plans for upper elementary students focusing on the built environment. The first lesson plan, "The Built Environment--An Integrating Theme" (Liesa Schroeder), offers suggestions for developing a walking tour around the school neighborhood, a historic area, or a city square. It finds that…
Monkeys and Walks Muhammad Waliji
May, J. Peter
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
A Leadership Walk across Gettysburg
ERIC Educational Resources Information Center
Millward, Robert E.
2009-01-01
School administrators find the Civil War battlefield an appropriate venue for fully appreciating the role of vision, mentoring and the power of words. The author, a professor at Indiana University of Pennsylvania, has organized leadership walks across Gettysburg for superintendents and principals for a decade. This article describes the…
Bush, John W.M.
Water-Walking Submitted by David L. Hu, Brian Chan, and John W. M. Bush, Massachusetts Institute of Technology The water strider Fig. 1 is an insect of characteristic length 1 cm and weight 10 dynes of hairs that render its legs effectively nonwetting.1 The water strider propels itself by driving its
ERIC Educational Resources Information Center
Weir, Phil
1994-01-01
During a walk, an outdoor education teacher reflects on the status of outdoor education in Ottawa (Canada) and importance of maintaining a close relationship with nature. He looks for signs of an old log home site, observes a hawk's flight, discovers remains of a plastic bag in an owl pellet, and realizes that everyone is working on survival. (LP)
Successful Statewide Walking Program Websites
ERIC Educational Resources Information Center
Teran, Bianca Maria; Hongu, Nobuko
2012-01-01
Statewide Extension walking programs are making an effort to increase physical activity levels in America. An investigation of all 20 of these programs revealed that 14 use websites as marketing and educational tools, which could prove useful as the popularity of Internet communities continues to grow. Website usability information and an analysis…
Listening Walks and Singing Maps
ERIC Educational Resources Information Center
Cardany, Audrey Berger
2011-01-01
The Listening Walk by Paul Showers and illustrated by Aliki, and "It's My City: A Singing Map" by April Pulley Sayre with pictures by Denis Roche, provide two examples of texts that aid in building children's phonological awareness for reading and music. The author describes each narrative and discusses its function as a springboard to composition…
Clairvoyant scheduling of random walks
Gacs, Peter
Â´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. PÂ´eter GÂ´acs (BU) Clairvoyant
Gait velocity and walking distance to predict community walking after stroke.
An, SeungHeon; Lee, YunBok; Shin, HyeonHui; Lee, GyuChang
2015-12-01
Gait speed and walking distance were evaluated as predictors for levels of community walking after stroke. In this study, 103 stroke survivors were identified as limited (n?=?67) or independent community walkers (n?=?36). Ten meter and six min walk tests were used to measure gait speed and walking distance, respectively. The discriminative properties of gait speed and walking distance for community walking were investigated using receiver operating characteristic curves. Cut-off values of 0.87?m/s for community walking gait speed for walking distance had positive predictive values of 65% and 55%, respectively. The negative predictive value ranged from 89% for gait speed to 79% for walking distance. Gait speed and walking distance showed significant differences between limited and independent community walking. Gait speed was more significantly related to community walking than walking distance. The results of this study suggest that gait speed is a better predictor for community walking than walking distance in moderately affected post-stroke survivors. PMID:26310714
Electric quantum walks in two dimensions
Luis A. Bru; Margarida Hinarejos; Fernando Silva; Germán J. de Valcárcel; Eugenio Roldán
2015-12-23
We study electric quantum walks in two dimensions considering Grover, Alternate, Hadamard, and DFT quantum walks. In the Grover walk the behaviour under an electric field is easy to summarize: when the field direction coincides with the x or y axes, it produces a transient trapping of the probability distribution along the direction of the field, while when it is directed along the diagonals, a perfect 2D trapping is frustrated. The analysis of the alternate walk helps to understand the behaviour of the Grover walk as both walks are partially equivalent; in particular, it helps to understand the role played by the existence of conical intersections in the dispersion relations, as we show that when these are removed a perfect 2D trapping can occur for suitable directions of the field. We complete our study with the electric DFT and Hadamard walks in 2D, showing that the latter can exhibit perfect 2D trapping.
Biased random walks on multiplex networks
Battiston, Federico; Latora, Vito
2015-01-01
Biased random walks on complex networks are a particular type of walks whose motion is biased on properties of the destination node, such as its degree. In recent years they have been exploited to design efficient strategies to explore a network, for instance by constructing maximally mixing trajectories or by sampling homogeneously the nodes. In multiplex networks, the nodes are related through different types of links (layers or communication channels), and the presence of connections at different layers multiplies the number of possible paths in the graph. In this work we introduce biased random walks on multiplex networks and provide analytical solutions for their long-term properties such as the stationary distribution and the entropy rate. We focus on degree-biased walks and distinguish between two subclasses of random walks: extensive biased walks consider the properties of each node separately at each layer, intensive biased walks deal instead with intrinsically multiplex variables. We study the effec...
To Walk or Not to Walk?: The Hierarchy of Walking Needs
ERIC Educational Resources Information Center
Alfonzo, Mariela
2005-01-01
The multitude of quality of life problems associated with declining walking rates has impelled researchers from various disciplines to identify factors related to this behavior change. Currently, this body of research is in need of a transdisciplinary, multilevel theoretical model that can help explain how individual, group, regional, and…
Spatial search by quantum walk
NASA Astrophysics Data System (ADS)
Childs, Andrew M.; Goldstone, Jeffrey
2004-08-01
Grover’s quantum search algorithm provides a way to speed up combinatorial search, but is not directly applicable to searching a physical database. Nevertheless, Aaronson and Ambainis showed that a database of N items laid out in d spatial dimensions can be searched in time of order N for d>2 , and in time of order Npoly(logN) for d=2 . We consider an alternative search algorithm based on a continuous-time quantum walk on a graph. The case of the complete graph gives the continuous-time search algorithm of Farhi and Gutmann, and other previously known results can be used to show that N speedup can also be achieved on the hypercube. We show that full N speedup can be achieved on a d -dimensional periodic lattice for d>4 . In d=4 , the quantum walk search algorithm takes time of order Npoly(logN) , and in d<4 , the algorithm does not provide substantial speedup.
Correlated continuous time random walks
Meerschaert, Mark M; Xiao, Yimin
2008-01-01
Continuous time random walks impose a random waiting time before each particle jump. Scaling limits of heavy tailed continuous time random walks are governed by fractional evolution equations. Space-fractional derivatives describe heavy tailed jumps, and the time-fractional version codes heavy tailed waiting times. This paper develops scaling limits and governing equations in the case of correlated jumps. For long-range dependent jumps, this leads to fractional Brownian motion or linear fractional stable motion, with the time parameter replaced by an inverse stable subordinator in the case of heavy tailed waiting times. These scaling limits provide an interesting class of non-Markovian, non-Gaussian self-similar processes.
Continuous Limit of Discrete Quantum Walks
Dheeraj M N; Todd A. Brun
2015-01-27
Quantum walks can be defined in two quite distinct ways: discrete-time and continuous-time quantum walks (DTQWs and CTQWs). For classical random walks, there is a natural sense in which continuous-time walks are a limit of discrete-time walks. Quantum mechanically, in the discrete-time case, an additional "coin space" must be appended for the walk to have nontrivial time evolution. Continuous-time quantum walks, however, have no such constraints. This means that there is no completely straightforward way to treat a CTQW as a limit of DTQW, as can be done in the classical case. Various approaches to this problem have been taken in the past. We give a construction for walks on $d$-regular, $d$-colorable graphs when the coin flip operator is Hermitian: from a standard DTQW we construct a family of discrete-time walks with a well-defined continuous-time limit on a related graph. One can think of this limit as a {\\it coined} continuous-time walk. We show that these CTQWs share some properties with coined DTQWs. In particular, we look at spatial search by a DTQW over the 2-D torus (a grid with periodic boundary conditions) of size $\\sqrt{N}\\times\\sqrt{N}$, where it was shown \
Positive messaging promotes walking in older adults.
Notthoff, Nanna; Carstensen, Laura L
2014-06-01
Walking is among the most cost-effective and accessible means of exercise. Mounting evidence suggests that walking may help to maintain physical and cognitive independence in old age by preventing a variety of health problems. However, older Americans fall far short of meeting the daily recommendations for walking. In 2 studies, we examined whether considering older adults' preferential attention to positive information may effectively enhance interventions aimed at promoting walking. In Study 1, we compared the effectiveness of positive, negative, and neutral messages to encourage walking (as measured with pedometers). Older adults who were informed about the benefits of walking walked more than those who were informed about the negative consequences of failing to walk, whereas younger adults were unaffected by framing valence. In Study 2, we examined within-person change in walking in older adults in response to positively- or negatively-framed messages over a 28-day period. Once again, positively-framed messages more effectively promoted walking than negatively-framed messages, and the effect was sustained across the intervention period. Together, these studies suggest that consideration of age-related changes in preferences for positive and negative information may inform the design of effective interventions to promote healthy lifestyles. Future research is needed to examine the mechanisms underlying the greater effectiveness of positively- as opposed to negatively-framed messages and the generalizability of findings to other intervention targets and other subpopulations of older adults. PMID:24956001
Positive messaging promotes walking in older adults
Notthoff, Nanna; Carstensen, Laura L.
2014-01-01
Walking is among the most cost-effective and accessible means of exercise. Mounting evidence suggests that walking may help to maintain physical and cognitive independence in old age by preventing a variety of health problems. However, older Americans fall far short of meeting the daily recommendations for walking. In two studies, we examined whether considering older adults’ preferential attention to positive information may effectively enhance interventions aimed at promoting walking. In Study 1, we compared the effectiveness of positive, negative, and neutral messages to encourage walking (as measured with pedometers). Older adults who were informed about the benefits of walking walked more than those who were informed about the negative consequences of failing to walk, whereas younger adults were unaffected by framing valence. In Study 2, we examined within-person change in walking in older adults in response to positively- or negatively-framed messages over a 28-day period. Once again, positively-framed messages more effectively promoted walking than negatively-framed messages, and the effect was sustained across the intervention period. Together, these studies suggest that consideration of age-related changes in preferences for positive and negative information may inform the design of effective interventions to promote healthy lifestyles. Future research is needed to examine the mechanisms underlying the greater effectiveness of positively as opposed to negatively framed messages and the generalizability of findings to other intervention targets and other subpopulations of older adults. PMID:24956001
Quantum walks with infinite hitting times
Hari Krovi; Todd A. Brun
2006-06-10
Hitting times are the average time it takes a walk to reach a given final vertex from a given starting vertex. The hitting time for a classical random walk on a connected graph will always be finite. We show that, by contrast, quantum walks can have infinite hitting times for some initial states. We seek criteria to determine if a given walk on a graph will have infinite hitting times, and find a sufficient condition, which for discrete time quantum walks is that the degeneracy of the evolution operator be greater than the degree of the graph. The set of initial states which give an infinite hitting time form a subspace. The phenomenon of infinite hitting times is in general a consequence of the symmetry of the graph and its automorphism group. Using the irreducible representations of the automorphism group, we derive conditions such that quantum walks defined on this graph must have infinite hitting times for some initial states. In the case of the discrete walk, if this condition is satisfied the walk will have infinite hitting times for any choice of a coin operator, and we give a class of graphs with infinite hitting times for any choice of coin. Hitting times are not very well-defined for continuous time quantum walks, but we show that the idea of infinite hitting-time walks naturally extends to the continuous time case as well.
Universal computation by quantum walk.
Childs, Andrew M
2009-05-01
In some of the earliest work on quantum computing, Feynman showed how to implement universal quantum computation with a time-independent Hamiltonian. I show that this remains possible even if the Hamiltonian is restricted to be the adjacency matrix of a low-degree graph. Thus quantum walk can be regarded as a universal computational primitive, with any quantum computation encoded in some graph. The main idea is to implement quantum gates by scattering processes. PMID:19518851
Annegarn, Janneke; Spruit, Martijn A.; Savelberg, Hans H. C. M.; Willems, Paul J. B.; van Bool, Coby; Schols, Annemie M. W. J.; Wouters, Emiel F. M.; Meijer, Kenneth
2012-01-01
Background To date, detailed analyses of walking patterns using accelerometers during the 6-min walk test (6MWT) have not been performed in patients with chronic obstructive pulmonary disease (COPD). Therefore, it remains unclear whether and to what extent COPD patients have an altered walking pattern during the 6MWT compared to healthy elderly subjects. Methodology/Principal Findings 79 COPD patients and 24 healthy elderly subjects performed the 6MWT wearing an accelerometer attached to the trunk. The accelerometer features (walking intensity, cadence, and walking variability) and subject characteristics were assessed and compared between groups. Moreover, associations were sought with 6-min walk distance (6MWD) using multiple ordinary least squares (OLS) regression models. COPD patients walked with a significantly lower walking intensity, lower cadence and increased walking variability compared to healthy subjects. Walking intensity and height were the only two significant determinants of 6MWD in healthy subjects, explaining 85% of the variance in 6MWD. In COPD patients also age, cadence, walking variability measures and their interactions were included were significant determinants of 6MWD (total variance in 6MWD explained: 88%). Conclusions/Significance COPD patients have an altered walking pattern during 6MWT compared to healthy subjects. These differences in walking pattern partially explain the lower 6MWD in patients with COPD. PMID:22624017
Lévy Walks Suboptimal under Predation Risk
Abe, Masato S.; Shimada, Masakazu
2015-01-01
A key challenge in movement ecology is to understand how animals move in nature. Previous studies have predicted that animals should perform a special class of random walks, called Lévy walk, to obtain more targets. However, some empirical studies did not support this hypothesis, and the relationship between search strategy and ecological factors is still unclear. We focused on ecological factors, such as predation risk, and analyzed whether Lévy walk may not be favored. It was remarkable that the ecological factors often altered an optimal search strategy from Lévy walk to Brownian walk, depending on the speed of the predator’s movement, density of predators, etc. This occurred because higher target encounter rates simultaneously led searchers to higher predation risks. Our findings indicate that animals may not perform Lévy walks often, and we suggest that it is crucial to consider the ecological context for evaluating the search strategy performed by animals in the field. PMID:26544687
Lévy Walks Suboptimal under Predation Risk.
Abe, Masato S; Shimada, Masakazu
2015-11-01
A key challenge in movement ecology is to understand how animals move in nature. Previous studies have predicted that animals should perform a special class of random walks, called Lévy walk, to obtain more targets. However, some empirical studies did not support this hypothesis, and the relationship between search strategy and ecological factors is still unclear. We focused on ecological factors, such as predation risk, and analyzed whether Lévy walk may not be favored. It was remarkable that the ecological factors often altered an optimal search strategy from Lévy walk to Brownian walk, depending on the speed of the predator's movement, density of predators, etc. This occurred because higher target encounter rates simultaneously led searchers to higher predation risks. Our findings indicate that animals may not perform Lévy walks often, and we suggest that it is crucial to consider the ecological context for evaluating the search strategy performed by animals in the field. PMID:26544687
Walking Wave as a Model of Particle
A. V. Goryunov
2012-05-02
The concept of walking wave is introduced from classical relativistic positions. One- and three-dimensional walking waves considered with their wave equations and dispersion equations. It is shown that wave characteristics (de Broglie's and Compton's wavelengths) and corpuscular characteristics (energy-momentum vector and the rest mass) of particle may be expressed through parameters of walking wave. By that the new view on a number concepts of physic related with wave-particle duality is suggested.
Walking gauge dynamics and realistic technicolor
Sundrum, R. Department of Physics, University of California, Berkeley 94720 )
1992-02-05
A realistic technicolor model, effective below 150 TeV is outlined. The new feature of the model is that the third generation quarks are unified with the technifermions into multiplets of a walking gauge force down to a scale of [similar to]10 TeV. Because they directly feel the walking force these quarks can have mass enhancements even greater than those of conventional walking schemes. Electroweak radiative corrections are estimable and within experimental limits.
75 FR 185 - Energy Conservation Program: Test Procedures for Walk-In Coolers and Walk-In Freezers
Federal Register 2010, 2011, 2012, 2013, 2014
2010-01-04
...The terms ``walk-in cooler'' and ``walk-in freezer...The terms ``walk-in cooler'' and ``walk-in freezer...and EER = EER of walk-in (cooler or freezer), Btu/Wh. 3...for anti-sweat or anti-freeze application); lights...
Random walks between leaves of random networks
NASA Astrophysics Data System (ADS)
Lancaster, David
2014-02-01
Motivated by the desire to model internet traffic we consider random walks that start and are absorbed on the leaves of random networks and study the length of such walks. We present and test two techniques to analyse these walks. On Erd?s-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.
Cell phones change the way we walk.
Lamberg, Eric M; Muratori, Lisa M
2012-04-01
Cell phone use among pedestrians leads to increased cognitive distraction, reduced situation awareness and increases in unsafe behavior. Performing a dual-task, such as talking or texting with a cell phone while walking, may interfere with working memory and result in walking errors. At baseline, thirty-three participants visually located a target 8m ahead; then vision was occluded and they were instructed to walk to the remembered target. One week later participants were assigned to either walk, walk while talking on a cell phone, or walk while texting on a cell phone toward the target with vision occluded. Duration and final location of the heel were noted. Linear distance traveled, lateral angular deviation from the start line, and gait velocity were derived. Changes from baseline to testing were analyzed with paired t-tests. Participants engaged in cell phone use presented with significant reductions in gait velocity (texting: 33% reduction, p=0.01; talking: 16% reduction, p=0.02). Moreover, participants who were texting while walking demonstrated a 61% increase in lateral deviation (p=0.04) and 13% increase in linear distance traveled (p=0.03). These results suggest that the dual-task of walking while using a cell phone impacts executive function and working memory and influences gait to such a degree that it may compromise safety. Importantly, comparison of the two cell phone conditions demonstrates texting creates a significantly greater interference effect on walking than talking on a cell phone. PMID:22226937
Walking-age analyzer for healthcare applications.
Jin, Bo; Thu, Tran Hoai; Baek, Eunhye; Sakong, SungHwan; Xiao, Jin; Mondal, Tapas; Deen, M Jamal
2014-05-01
This paper describes a walking-age pattern analysis and identification system using a 3-D accelerometer and a gyroscope. First, a walking pattern database from 79 volunteers of ages ranging from 10 to 83 years is constructed. Second, using feature extraction and clustering, three distinct walking-age groups, children of ages 10 and below, adults in 20-60s, and elders in 70s and 80s, were identified. For this study, low-pass filtering, empirical mode decomposition, and K-means were used to process and analyze the experimental results. Analysis shows that volunteers' walking-ages can be categorized into distinct groups based on simple walking pattern signals. This grouping can then be used to detect persons with walking patterns outside their age groups. If the walking pattern puts an individual in a higher "walking age" grouping, then this could be an indicator of potential health/walking problems, such as weak joints, poor musculoskeletal support system or a tendency to fall. PMID:24808231
Efficient quantum circuit implementation of quantum walks
Douglas, B. L.; Wang, J. B.
2009-05-15
Quantum walks, being the quantum analog of classical random walks, are expected to provide a fruitful source of quantum algorithms. A few such algorithms have already been developed, including the 'glued trees' algorithm, which provides an exponential speedup over classical methods, relative to a particular quantum oracle. Here, we discuss the possibility of a quantum walk algorithm yielding such an exponential speedup over possible classical algorithms, without the use of an oracle. We provide examples of some highly symmetric graphs on which efficient quantum circuits implementing quantum walks can be constructed and discuss potential applications to quantum search for marked vertices along these graphs.
On the Levy-walk Nature of Human Mobility: Do Humans Walk like Monkeys?
Young, R. Michael
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
CDC Vital Signs: More People Walk to Better Health
... physically active. *Aerobic activities like brisk walking, running, swimming and bicycling make you breathe harder and make ... Help others walk more safely by driving the speed limit and yielding to people who walk. Use ...
Franceschini, Marco; Rampello, Anais; Agosti, Maurizio; Massucci, Maurizio; Bovolenta, Federica; Sale, Patrizio
2013-01-01
Walking ability, though important for quality of life and participation in social and economic activities, can be adversely affected by neurological disorders, such as Spinal Cord Injury, Stroke, Multiple Sclerosis or Traumatic Brain Injury. The aim of this study is to evaluate if the energy cost of walking (CW), in a mixed group of chronic patients with neurological diseases almost 6 months after discharge from rehabilitation wards, can predict the walking performance and any walking restriction on community activities, as indicated by Walking Handicap Scale categories (WHS). One hundred and seven subjects were included in the study, 31 suffering from Stroke, 26 from Spinal Cord Injury and 50 from Multiple Sclerosis. The multivariable binary logistical regression analysis has produced a statistical model with good characteristics of fit and good predictability. This model generated a cut-off value of.40, which enabled us to classify correctly the cases with a percentage of 85.0%. Our research reveal that, in our subjects, CW is the only predictor of the walking performance of in the community, to be compared with the score of WHS. We have been also identifying a cut-off value of CW cost, which makes a distinction between those who can walk in the community and those who cannot do it. In particular, these values could be used to predict the ability to walk in the community when discharged from the rehabilitation units, and to adjust the rehabilitative treatment to improve the performance. PMID:23468871
Franceschini, Marco; Rampello, Anais; Agosti, Maurizio; Massucci, Maurizio; Bovolenta, Federica; Sale, Patrizio
2013-01-01
Walking ability, though important for quality of life and participation in social and economic activities, can be adversely affected by neurological disorders, such as Spinal Cord Injury, Stroke, Multiple Sclerosis or Traumatic Brain Injury. The aim of this study is to evaluate if the energy cost of walking (CW), in a mixed group of chronic patients with neurological diseases almost 6 months after discharge from rehabilitation wards, can predict the walking performance and any walking restriction on community activities, as indicated by Walking Handicap Scale categories (WHS). One hundred and seven subjects were included in the study, 31 suffering from Stroke, 26 from Spinal Cord Injury and 50 from Multiple Sclerosis. The multivariable binary logistical regression analysis has produced a statistical model with good characteristics of fit and good predictability. This model generated a cut-off value of.40, which enabled us to classify correctly the cases with a percentage of 85.0%. Our research reveal that, in our subjects, CW is the only predictor of the walking performance of in the community, to be compared with the score of WHS. We have been also identifying a cut-off value of CW cost, which makes a distinction between those who can walk in the community and those who cannot do it. In particular, these values could be used to predict the ability to walk in the community when discharged from the rehabilitation units, and to adjust the rehabilitative treatment to improve the performance. PMID:23468871
Gaitography applied to prosthetic walking.
Roerdink, Melvyn; Cutti, Andrea G; Summa, Aurora; Monari, Davide; Veronesi, Davide; van Ooijen, Mariëlle W; Beek, Peter J
2014-11-01
During walking on an instrumented treadmill with an embedded force platform or grid of pressure sensors, center-of-pressure (COP) trajectories exhibit a characteristic butterfly-like shape, reflecting the medio-lateral and anterior-posterior weight shifts associated with alternating steps. We define "gaitography" as the analysis of such COP trajectories during walking (the "gaitograms"). It is currently unknown, however, if gaitography can be employed to characterize pathological gait, such as lateralized gait impairments. We therefore registered gaitograms for a heterogeneous sample of persons with a trans-femoral and trans-tibial amputation during treadmill walking at a self-selected comfortable speed. We found that gaitograms directly visualize between-person differences in prosthetic gait in terms of step width and the relative duration of prosthetic and non-prosthetic single-support stance phases. We further demonstrated that one should not only focus on the gaitogram's shape but also on the time evolution along that shape, given that the COP evolves much slower in the single-support phase than in the double-support phase. Finally, commonly used temporal and spatial prosthetic gait characteristics were derived, revealing both individual and systematic differences in prosthetic and non-prosthetic step lengths, step times, swing times, and double-support durations. Because gaitograms can be rapidly collected in an unobtrusive and markerless manner over multiple gait cycles without constraining foot placement, clinical application of gaitography seems both expedient and appealing. Studies examining the repeatability of gaitograms and evaluating gaitography-based gait characteristics against a gold standard with known validity and reliability are required before gaitography can be clinically applied. PMID:25249276
Visual Acuity During Treadmill Walking
NASA Technical Reports Server (NTRS)
Peters, B. T.; Brady, R.; vanEmmerik, R. E. A.; Bloomberg, Jacob J.
2006-01-01
An awareness of the physical world is essential for successful navigation through the environment. Vision is the means by which this awareness is made possible for most people. However, without adequate compensation, the movements of the body during walking could impair vision. Previous research has shown how the eyes, head and trunk movements are coordinated to provide the compensation necessary for clear vision, but the overall effectiveness of these coordinated movements is unknown. The goal of the research presented here was to provide a direct measure of visual performance during locomotion, while also investigating the degree to which coordinated head and body movements can be altered to facilitate the goal of seeing clearly.
Random Walks Estimate Land Value
Blanchard, Ph
2010-01-01
Expected urban population doubling calls for a compelling theory of the city. Random walks and diffusions defined on spatial city graphs spot hidden areas of geographical isolation in the urban landscape going downhill. First--passage time to a place correlates with assessed value of land in that. The method accounting the average number of random turns at junctions on the way to reach any particular place in the city from various starting points could be used to identify isolated neighborhoods in big cities with a complex web of roads, walkways and public transport systems.
Welly-Walks for Science Learning
ERIC Educational Resources Information Center
Fradley, Carol
2006-01-01
This article discusses how a regular walk in the wind or the rain can help develop science knowledge and skills. The author describes one "welly-walk" and links it to National Curriculum for England requirements so that readers can see how easy it is. (Contains 1 figure and 1 box.)
Walking economy in people with Parkinson's disease
Christiansen, Cory L; Schenkman, Margaret L; McFann, Kim; Wolfe, Pamela; Kohrt, Wendy M
2009-01-01
Gait dysfunction is an early problem identified by patients with Parkinson's disease (PD). Alterations in gait may result in an increase in the energy cost of walking (i.e., walking economy). The purpose of this study was to determine whether walking economy is atypical in patients with PD when compared with healthy controls. A secondary purpose was to evaluate the associations of age, sex, and level of disease severity with walking economy in patients with PD. The rate of oxygen consumption (VO2) and other responses to treadmill walking were compared in 90 patients (64.4±10.3 yr) and 44 controls (64.6±7.3 yr) at several walking speeds. Pearson correlation coefficients (r) were calculated to determine relationships of age, sex, and disease state with walking economy in PD patients. Walking economy was significantly worse in PD patients than in controls at all speeds above 1.0 mph. Across all speeds, VO2 was 6 to 10% higher in PD patients. Heart rate, minute ventilation, respiratory exchange ratio, and rating of perceived exertion were correspondingly elevated. No significant relationship of age, sex, or UPDRS score with VO2 was found for patients with PD. The findings suggest that the physiologic stress of daily physical activities is increased in patients with early to mid-stage PD, and this may contribute to the elevated level of fatigue that is characteristic of PD. PMID:19441128
Discrete quantum walk on a binary tree
NASA Astrophysics Data System (ADS)
Dimcovic, Zlatko; Milligan, Ian; Rockwell, Dan; Burton, Robert M.; Nguyen, Thinh; Kovchegov, Yevgeniy
2011-03-01
We have recently constructed a framework for quantum walks, based on classical walks with memory. This framework reproduces known walks, while it can be used to build walks in systems that are difficult for current approaches. As our first example of its utility, we study a symmetric discrete quantum walk on the infinite binary tree. For a walk starting from a pure state at a given level in the tree, we compute the amplitude at the root, as a function of time and starting level. The result is strikingly different from the classical case, as its amplitude spans an order of magnitude, with a power law tail, while the classical one decays exponentially. (For example, for a delayed walk this property yields a polynomial vs. exponential speed up over the classical walk, in delay time.) The breadth of the probability peak indicates that any restriction of the extent of the tree, such as a matching tree, sinks or boundaries, would likely yield algorithms superior to classical. The calculation utilizes a variety of analytical techniques (memoried stochastic processes, combinatorics and path counting, transforms, steepest descent, orthogonal polynomials). This study also brings up interesting general questions about quantum processes on such structures.
Walking economy in people with Parkinson's disease.
Christiansen, Cory L; Schenkman, Margaret L; McFann, Kim; Wolfe, Pamela; Kohrt, Wendy M
2009-07-30
Gait dysfunction is an early problem identified by patients with Parkinson's disease (PD). Alterations in gait may result in an increase in the energy cost of walking (i.e., walking economy). The purpose of this study was to determine whether walking economy is atypical in patients with PD when compared with healthy controls. A secondary purpose was to evaluate the associations of age, sex, and level of disease severity with walking economy in patients with PD. The rate of oxygen consumption (VO(2)) and other responses to treadmill walking were compared in 90 patients (64.4 +/- 10.3 years) and 44 controls (64.6 +/- 7.3 years) at several walking speeds. Pearson correlation coefficients (r) were calculated to determine relationships of age, sex, and disease state with walking economy in PD patients. Walking economy was significantly worse in PD patients than in controls at all speeds above 1.0 mph. Across all speeds, VO(2) was 6 to 10% higher in PD patients. Heart rate, minute ventilation, respiratory exchange ratio, and rating of perceived exertion were correspondingly elevated. No significant relationship of age, sex, or UPDRS score with VO(2) was found for patients with PD. The findings suggest that the physiologic stress of daily physical activities is increased in patients with early to mid-stage PD, and this may contribute to the elevated level of fatigue that is characteristic of PD. PMID:19441128
Walking in circles: a modelling approach
Maus, Horst-Moritz; Seyfarth, Andre
2014-01-01
Blindfolded or disoriented people have the tendency to walk in circles rather than on a straight line even if they wanted to. Here, we use a minimalistic walking model to examine this phenomenon. The bipedal spring-loaded inverted pendulum exhibits asymptotically stable gaits with centre of mass (CoM) dynamics and ground reaction forces similar to human walking in the sagittal plane. We extend this model into three dimensions, and show that stable walking patterns persist if the leg is aligned with respect to the body (here: CoM velocity) instead of a world reference frame. Further, we demonstrate that asymmetric leg configurations, which are common in humans, will typically lead to walking in circles. The diameter of these circles depends strongly on parameter configuration, but is in line with empirical data from human walkers. Simulation results suggest that walking radius and especially direction of rotation are highly dependent on leg configuration and walking velocity, which explains inconsistent veering behaviour in repeated trials in human data. Finally, we discuss the relation between findings in the model and implications for human walking. PMID:25056215
ERIC Educational Resources Information Center
Granada, Janet; Vriesenga, Michael
2008-01-01
Walk-through classroom observations are an effective way for principals to learn about and shape instruction and culture in their schools. But many principals don't use walk-throughs to their potential because of the time it takes to store, process, analyze, and give feedback. To facilitate the use of this valuable observation tool, the Kentucky…
Walking in circles: a modelling approach.
Maus, Horst-Moritz; Seyfarth, Andre
2014-10-01
Blindfolded or disoriented people have the tendency to walk in circles rather than on a straight line even if they wanted to. Here, we use a minimalistic walking model to examine this phenomenon. The bipedal spring-loaded inverted pendulum exhibits asymptotically stable gaits with centre of mass (CoM) dynamics and ground reaction forces similar to human walking in the sagittal plane. We extend this model into three dimensions, and show that stable walking patterns persist if the leg is aligned with respect to the body (here: CoM velocity) instead of a world reference frame. Further, we demonstrate that asymmetric leg configurations, which are common in humans, will typically lead to walking in circles. The diameter of these circles depends strongly on parameter configuration, but is in line with empirical data from human walkers. Simulation results suggest that walking radius and especially direction of rotation are highly dependent on leg configuration and walking velocity, which explains inconsistent veering behaviour in repeated trials in human data. Finally, we discuss the relation between findings in the model and implications for human walking. PMID:25056215
Cognitive Resource Demands of Redirected Walking.
Bruder, Gerd; Lubas, Paul; Steinicke, Frank
2015-04-01
Redirected walking allows users to walk through a large-scale immersive virtual environment (IVE) while physically remaining in a reasonably small workspace. Therefore, manipulations are applied to virtual camera motions so that the user's self-motion in the virtual world differs from movements in the real world. Previous work found that the human perceptual system tolerates a certain amount of inconsistency between proprioceptive, vestibular and visual sensation in IVEs, and even compensates for slight discrepancies with recalibrated motor commands. Experiments showed that users are not able to detect an inconsistency if their physical path is bent with a radius of at least 22 meters during virtual straightforward movements. If redirected walking is applied in a smaller workspace, manipulations become noticeable, but users are still able to move through a potentially infinitely large virtual world by walking. For this semi-natural form of locomotion, the question arises if such manipulations impose cognitive demands on the user, which may compete with other tasks in IVEs for finite cognitive resources. In this article we present an experiment in which we analyze the mutual influence between redirected walking and verbal as well as spatial working memory tasks using a dual-tasking method. The results show an influence of redirected walking on verbal as well as spatial working memory tasks, and we also found an effect of cognitive tasks on walking behavior. We discuss the implications and provide guidelines for using redirected walking in virtual reality laboratories. PMID:26357104
Interface Reconstruction with Directional Walking
Yao, J
2009-05-22
Young's interface reconstruction with three-dimensional arbitrary mesh, in general, is rather tedious to implement compared to the case of a regular mesh. The main difficulty comes from the construction of a planar facet that bounds a certain volume inside a cell. Unlike the five basic configurations with a Cartesian mesh, there can be a great number of different configurations in the case of a general mesh. We represent a simple method that can derive the topology/geometry of the intersection of arbitrary planar objects in a uniform way. The method is based on a directional walking on the surface of objects, and links the intersection points with the paths of the walking naturally defining the intersection of objects. The method works in both two and three dimensions. The method does not take advantage of convexity, thus decomposition of an object is not necessary. Therefore, the solution with this method will have a reduced number of edges and less data storage, compared with methods that use shape decomposition. The treatment is general for arbitrary polyhedrons, and no look-up tables are needed. The same operation can easily be extended for curved geometry. The implementation of this new algorithm shall allow the interface reconstruction on an arbitrary mesh to be as simple as it is on a regular mesh. Furthermore, we exactly compute the integral of partial cell volume bounded by quadratic interface. Therefore, interface reconstruction with higher than second order accuracy can be achieved on an arbitrary mesh.
Hitting time of quantum walks with perturbation
NASA Astrophysics Data System (ADS)
Chiang, Chen-Fu; Gomez, Guillermo
2013-01-01
The hitting time is the required minimum time for a Markov chain-based walk (classical or quantum) to reach a target state in the state space. We investigate the effect of the perturbation on the hitting time of a quantum walk. We obtain an upper bound for the perturbed quantum walk hitting time by applying Szegedy's work and the perturbation bounds with Weyl's perturbation theorem on classical matrix. Based on the definition of quantum hitting time given in MNRS algorithm, we further compute the delayed perturbed hitting time and delayed perturbed quantum hitting time (DPQHT). We show that the upper bound for DPQHT is bounded from above by the difference between the square root of the upper bound for a perturbed random walk and the square root of the lower bound for a random walk.
Go Naked: Diapers Affect Infant Walking
Cole, Whitney G.; Lingeman, Jesse M.; Adolph, Karen E.
2013-01-01
In light of cross-cultural and experimental research highlighting effects of childrearing practices on infant motor skill, we asked whether wearing diapers, a seemingly innocuous childrearing practice, affects infant walking. Diapers introduce bulk between the legs, potentially exacerbating infants’ poor balance and wide stance. We show that walking is adversely affected by old-fashioned cloth diapers, and that even modern disposable diapers—habitually worn by most infants in the sample—incur a cost relative to walking naked. Infants displayed less mature gait patterns and more missteps and falls while wearing diapers. Thus, infants’ own diapers constitute an on-going biomechanical perturbation while learning to walk. Furthermore, shifts in diapering practices may have contributed to historical and cross-cultural differences in infant walking. PMID:23106732
Go naked: diapers affect infant walking.
Cole, Whitney G; Lingeman, Jesse M; Adolph, Karen E
2012-11-01
In light of cross-cultural and experimental research highlighting effects of childrearing practices on infant motor skill, we asked whether wearing diapers, a seemingly innocuous childrearing practice, affects infant walking. Diapers introduce bulk between the legs, potentially exacerbating infants' poor balance and wide stance. We show that walking is adversely affected by old-fashioned cloth diapers, and that even modern disposable diapers - habitually worn by most infants in the sample - incur a cost relative to walking naked. Infants displayed less mature gait patterns and more missteps and falls while wearing diapers. Thus, infants' own diapers constitute an ongoing biomechanical perturbation while learning to walk. Furthermore, shifts in diapering practices may have contributed to historical and cross-cultural differences in infant walking. PMID:23106732
Efficient Quantum Walk on a Quantum Processor
Xiaogang Qiang; Thomas Loke; Ashley Montanaro; Kanin Aungskunsiri; Xiaoqi Zhou; Jeremy L. O'Brien; Jingbo Wang; Jonathan C. F. Matthews
2015-10-29
The random walk formalism is used across a wide range of applications, from modelling share prices to predicting population genetics. Likewise quantum walks have shown much potential as a frame- work for developing new quantum algorithms. In this paper, we present explicit efficient quantum circuits for implementing continuous-time quantum walks on the circulant class of graphs. These circuits allow us to sample from the output probability distributions of quantum walks on circulant graphs efficiently. We also show that solving the same sampling problem for arbitrary circulant quantum circuits is intractable for a classical computer, assuming conjectures from computational complexity theory. This is a new link between continuous-time quantum walks and computational complexity theory and it indicates a family of tasks which could ultimately demonstrate quantum supremacy over classical computers. As a proof of principle we have experimentally implemented the proposed quantum circuit on an example circulant graph using a two-qubit photonics quantum processor.
Hitting time for the continuous quantum walk
Martin Varbanov; Hari Krovi; Todd A. Brun
2008-03-24
We define the hitting (or absorbing) time for the case of continuous quantum walks by measuring the walk at random times, according to a Poisson process with measurement rate $\\lambda$. From this definition we derive an explicit formula for the hitting time, and explore its dependence on the measurement rate. As the measurement rate goes to either 0 or infinity the hitting time diverges; the first divergence reflects the weakness of the measurement, while the second limit results from the Quantum Zeno effect. Continuous-time quantum walks, like discrete-time quantum walks but unlike classical random walks, can have infinite hitting times. We present several conditions for existence of infinite hitting times, and discuss the connection between infinite hitting times and graph symmetry.
Hitting Time of Quantum Walks with Perturbation
Chen-Fu Chiang; Guillermo Gomez
2011-07-14
The hitting time is the required minimum time for a Markov chain-based walk (classical or quantum) to reach a target state in the state space. We investigate the effect of the perturbation on the hitting time of a quantum walk. We obtain an upper bound for the perturbed quantum walk hitting time by applying Szegedy's work and the perturbation bounds with Weyl's perturbation theorem on classical matrix. Based on the definition of quantum hitting time given in MNRS algorithm, we further compute the delayed perturbed hitting time (DPHT) and delayed perturbed quantum hitting time (DPQHT). We show that the upper bound for DPQHT is actually greater than the difference between the square root of the upper bound for a perturbed random walk and the square root of the lower bound for a random walk.
Quantum Search with Multiple Walk Steps per Oracle Query
Thomas G. Wong; Andris Ambainis
2015-07-22
We identify a key difference between quantum search by discrete- and continuous-time quantum walks: a discrete-time walk typically performs one walk step per oracle query, whereas a continuous-time walk can effectively perform multiple walk steps per query while only counting query time. As a result, we show that continuous-time quantum walks can outperform their discrete-time counterparts, even though both achieve quadratic speedups over their corresponding classical random walks. To provide greater equity, we allow the discrete-time quantum walk to also take multiple walk steps per oracle query while only counting queries. Then it matches the continuous-time algorithm's runtime, but such that it is a cubic speedup over its corresponding classical random walk. This yields the first example of a greater-than-quadratic speedup for quantum search over its corresponding classical random walk.
Quantum search with multiple walk steps per oracle query
NASA Astrophysics Data System (ADS)
Wong, Thomas G.; Ambainis, Andris
2015-08-01
We identify a key difference between quantum search by discrete- and continuous-time quantum walks: a discrete-time walk typically performs one walk step per oracle query, whereas a continuous-time walk can effectively perform multiple walk steps per query while only counting query time. As a result, we show that continuous-time quantum walks can outperform their discrete-time counterparts, even though both achieve quadratic speedups over their corresponding classical random walks. To provide greater equity, we allow the discrete-time quantum walk to also take multiple walk steps per oracle query while only counting queries. Then it matches the continuous-time algorithm's runtime, but such that it is a cubic speedup over its corresponding classical random walk. This yields a greater-than-quadratic speedup for quantum search over its corresponding classical random walk.
Dynamics of walking adaptation aftereffects induced in static images of walking actors.
Barraclough, Nick E; Ingham, Jennifer; Page, Stephen A
2012-04-15
Visual adaptation to walking actions results in subsequent aftereffects that bias perception of static images of walkers in different postures so that they are interpreted as walking in the opposite direction to the adapting actor. It is not clear, however, if the walking aftereffect is comparable to other well studied low- and high-level visual aftereffects. We therefore measured the dynamics of the walking aftereffect in order to assess the characteristics of the adapting mechanism. We found that walking aftereffects showed similar characteristic dynamics as for face aftereffects and some motion aftereffects. Walking aftereffects could be induced in a broad range of different static images of walking actors and were not restricted to images of actors in any particular posture. Walking aftereffects increased with adapting stimulus repetition and declined over time. The duration of the aftereffect was dependent upon time spent observing the adapting stimulus and could be well modelled by a power-law function that characterises this relationship in both face and motion aftereffects. Increasing the speed of the adapting stimulus by increasing actor walk speed increased aftereffect magnitude, as seen for some motion aftereffects. The nature of the aftereffects induced by observing walking actors indicates that they behave like traditional high-level visual aftereffects. PMID:22406522
Medical Aspects of Space Walking
NASA Technical Reports Server (NTRS)
Musgrave, Story
1999-01-01
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.
Quantum walks in curved spacetime
Pablo Arrighi; Stefano Facchini; Marcelo Forets
2015-05-26
A discrete-time Quantum Walk (QW) is essentially a unitary operator driving the evolution of a single particle on the lattice. Some QWs admit a continuum limit, leading to familiar PDEs (e.g. the Dirac equation), and thus provide us with discrete toy models of familiar particles (e.g. the electron). In this paper, we study the continuum limit of a wide class of QWs, and show that it leads to all those PDEs corresponding to the Hamiltonian form of the massive curved Dirac equation in (1 + 1) dimensions. Therefore a certain QW, which we make explicit, provides us with a unitary discrete toy model of the electron as a test particle in curved spacetime, in spite of the fixed background lattice. Mathematically we have introduced two novel ingredients for taking the continuum limit of a QW, but which apply to any quantum cellular automata: encoding and grouping.
The staggered quantum walk model
NASA Astrophysics Data System (ADS)
Portugal, R.; Santos, R. A. M.; Fernandes, T. D.; Gonçalves, D. N.
2015-10-01
There are at least three models of discrete-time quantum walks (QWs) on graphs currently under active development. In this work, we focus on the equivalence of two of them, known as Szegedy's and staggered QWs. We give a formal definition of the staggered model and discuss generalized versions for searching marked vertices. Using this formal definition, we prove that any instance of Szegedy's model is equivalent to an instance of the staggered model. On the other hand, we show that there are instances of the staggered model that cannot be cast into Szegedy's framework. Our analysis also works when there are marked vertices. We show that Szegedy's spatial search algorithms can be converted into search algorithms in staggered QWs. We take advantage of the similarity of those models to define the quantum hitting time in the staggered model and to describe a method to calculate the eigenvalues and eigenvectors of the evolution operator of staggered QWs.
Online ZMP Sampling Search for Biped Walking Planning
Veloso, Manuela M.
Online ZMP Sampling Search for Biped Walking Planning Jinsu Liu1,2 and Manuela Veloso2 1 Computer present a new method that uses random search for online planning of biped walking, given a feasible to solve the walking problem. We consider walk planning as the choice of a sequence of ZMPs leading
Reinforcement Learning Control for Biped Robot Walking on Uneven Surfaces
Reinforcement Learning Control for Biped Robot Walking on Uneven Surfaces Shouyi Wang, Jelmer of (passive) dynamic walking are far simpler than the traditional fully- controlled walking robots, while achieving a more natural gait and consuming less energy. However, lightly actuated dynamic walking robots
WALKING DIRECTIONS From the UHS Medical Center Office
Cantlon, Jessica F.
WALKING DIRECTIONS From the UHS Medical Center Office to the UHS Building on the River Campus Updated 5/2/12 University Health Service (UHS) in 1-5077 WALKING DIRECTIONS From the UHS Medical Center intersection. 2. Walk to the end of the hallway. Go down the stairs on your RIGHT. 3. Walk through the Flaum
Urban Walking and the Pedagogies of the Street
ERIC Educational Resources Information Center
Bairner, Alan
2011-01-01
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…
Walking and Eating Behavior of Toddlers at 12 Months Old
ERIC Educational Resources Information Center
Koda, Naoko; Akimoto, Yuko; Hirose, Toshiya; Hinobayashi, Toshihiko; Minami, Tetsuhiro
2004-01-01
Locomotive and eating behavior of 52 toddlers was observed at 12 months old in a nursery school and investigated in relation to the acquisition of independent walking. The toddlers who acquired walking ate more by themselves using the hands than the toddlers who did not start walking. This suggested that acquisition of walking was associated with…
Limit Theorems For the Grover Walk Without Memory
Clement Ampadu
2011-08-20
We consider the Grover walk as a 4-state quantum walk without memory in one dimension. The walker in our 4-state quantum walk moves to the left or right. We compute the stationary distribution of the walk, in addition, we obtain the weak limit theorem
Nordic Walking Practice Might Improve Plantar Pressure Distribution
ERIC Educational Resources Information Center
Perez-Soriano, Pedro; Llana-Belloch, Salvador; Martinez-Nova, Alfonso; Morey-Klapsing, G.; Encarnacion-Martinez, Alberto
2011-01-01
Nordic walking (NW), characterized by the use of two walking poles, is becoming increasingly popular (Morgulec-Adamowicz, Marszalek, & Jagustyn, 2011). We studied walking pressure patterns of 20 experienced and 30 beginner Nordic walkers. Plantar pressures from nine foot zones were measured during trials performed at two walking speeds (preferred…
Universal computation by multiparticle quantum walk.
Childs, Andrew M; Gosset, David; Webb, Zak
2013-02-15
A quantum walk is a time-homogeneous quantum-mechanical process on a graph defined by analogy to classical random walk. The quantum walker is a particle that moves from a given vertex to adjacent vertices in quantum superposition. We consider a generalization to interacting systems with more than one walker, such as the Bose-Hubbard model and systems of fermions or distinguishable particles with nearest-neighbor interactions, and show that multiparticle quantum walk is capable of universal quantum computation. Our construction could, in principle, be used as an architecture for building a scalable quantum computer with no need for time-dependent control. PMID:23413349
Decoherence in one-dimensional Quantum Walk
Mostafa Annabestani; Seyed Javad Akhtarshenas; Mohamad Reza Abolhassani
2009-10-11
In this paper we study decoherence in the quantum walk on the line. We generalize the method of decoherent coin quantum walk, introduced by Brun et al [Phys. Rev. A {\\bf 67}, 32304 (2003)]. Our analytical expressions are applicable for all kinds of decoherence. As an example of the coin-position decoherence, we study the broken line quantum walk and compare our results with the numerical one. We also show that our analytical results reduce to the Brun formalism when only the coin is subjected to decoherence.
Quantum Walk Schemes for Universal Quantum Computation
NASA Astrophysics Data System (ADS)
Underwood, Michael S.
Random walks are a powerful tool for the efficient implementation of algorithms in classical computation. Their quantum-mechanical analogues, called quantum walks, hold similar promise. Quantum walks provide a model of quantum computation that has recently been shown to be equivalent in power to the standard circuit model. As in the classical case, quantum walks take place on graphs and can undergo discrete or continuous evolution, though quantum evolution is unitary and therefore deterministic until a measurement is made. This thesis considers the usefulness of continuous-time quantum walks to quantum computation from the perspectives of both their fundamental power under various formulations, and their applicability in practical experiments. In one extant scheme, logical gates are effected by scattering processes. The results of an exhaustive search for single-qubit operations in this model are presented. It is shown that the number of distinct operations increases exponentially with the number of vertices in the scattering graph. A catalogue of all graphs on up to nine vertices that implement single-qubit unitaries at a specific set of momenta is included in an appendix. I develop a novel scheme for universal quantum computation called the discontinuous quantum walk, in which a continuous-time quantum walker takes discrete steps of evolution via perfect quantum state transfer through small 'widget' graphs. The discontinuous quantum-walk scheme requires an exponentially sized graph, as do prior discrete and continuous schemes. To eliminate the inefficient vertex resource requirement, a computation scheme based on multiple discontinuous walkers is presented. In this model, n interacting walkers inhabiting a graph with 2n vertices can implement an arbitrary quantum computation on an input of length n, an exponential savings over previous universal quantum walk schemes. This is the first quantum walk scheme that allows for the application of quantum error correction. The many-particle quantum walk can be viewed as a single quantum walk undergoing perfect state transfer on a larger weighted graph, obtained via equitable partitioning. I extend this formalism to non-simple graphs. Examples of the application of equitable partitioning to the analysis of quantum walks and many-particle quantum systems are discussed.
An experimental analysis of human straight walking
NASA Astrophysics Data System (ADS)
Li, Tao; Ceccarelli, Marco
2013-03-01
In this paper, an experimental analysis of human straight walking has been presented. Experiments on human walking were carried out by using Cassino tracking system which is a passive cable-based measuring system. This system is adopted because it is capable of both pose and wrench measurements with fairly simple monitoring of operation. By using experimental results, trajectories of a human limb extremity and its posture have been analyzed; forces that are exerted against cables by the limb of a person under test have been measured by force sensors as well. Furthermore, by using experimental tests, modeling and characterization of the human straight walking gait have been proposed.
Code of Federal Regulations, 2010 CFR
2010-01-01
...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...
Code of Federal Regulations, 2011 CFR
2011-01-01
...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...
propulsion increased with improved functional walking status, with the non-paretic leg muscles (i.e., rectus muscles (i.e., hamstrings) also increased as functional walking status improved. Power generation was alsoRelationships between muscle contributions to walking subtasks and functional walking status
76 FR 21579 - Energy Conservation Program: Test Procedures for Walk-In Coolers and Walk-In Freezers
Federal Register 2010, 2011, 2012, 2013, 2014
2011-04-15
...efficiency of certain walk-in cooler and walk-in freezer components...Definition of Walk-In Cooler or Freezer [[Page 21581...and EER = EER of walk-in (cooler or freezer), Btu/W-h...for anti-sweat or anti-freeze application); lights...
Redner, Sidney
Chapter 2 RANDOM WALK/DIFFUSION Because the random walk and its continuum diffusion limit underlie to this central topic. There are several complementary ways to describe random walks and diffusion, each that represents a minimalist description for the stochastic motion of a random walk. We mostly restrict ourselves
Walking on high heels changes muscle activity and the dynamics of human walking significantly.
Simonsen, Erik B; Svendsen, Morten B; Nørreslet, Andreas; Baldvinsson, Henrik K; Heilskov-Hansen, Thomas; Larsen, Peter K; Alkjær, Tine; Henriksen, Marius
2012-02-01
The aim of the study was to investigate the distribution of net joint moments in the lower extremities during walking on high-heeled shoes compared with barefooted walking at identical speed. Fourteen female subjects walked at 4 km/h across three force platforms while they were filmed by five digital video cameras operating at 50 frames/second. Both barefooted walking and walking on high-heeled shoes (heel height: 9 cm) were recorded. Net joint moments were calculated by 3D inverse dynamics. EMG was recorded from eight leg muscles. The knee extensor moment peak in the first half of the stance phase was doubled when walking on high heels. The knee joint angle showed that high-heeled walking caused the subjects to flex the knee joint significantly more in the first half of the stance phase. In the frontal plane a significant increase was observed in the knee joint abductor moment and the hip joint abductor moment. Several EMG parameters increased significantly when walking on high-heels. The results indicate a large increase in bone-on-bone forces in the knee joint directly caused by the increased knee joint extensor moment during high-heeled walking, which may explain the observed higher incidence of osteoarthritis in the knee joint in women as compared with men. PMID:22431211
Stable dynamic walking over uneven terrain
Manchester, Ian R.
We propose a constructive control design for stabilization of non-periodic trajectories of underactuated robots. An important example of such a system is an underactuated “dynamic walking” biped robot traversing rough or ...
Minimal walking technicolor: Setup for collider physics
Foadi, Roshan; Frandsen, Mads T.; Ryttov, Thomas A.; Sannino, Francesco
2007-09-01
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.
The hydrodynamics of water-walking arthropods
Bush, John W. M.
We present the results of a combined experimental and theoretical investigation of the dynamics of water-walking insects and spiders. Using high-speed videography, we describe their numerous gaits, some analogous to those ...
Random walk computations of diffusive fields
Lindstrom, Gregory Scot
1993-01-01
A numerical study of three problems is carried out using the gradient random walk method. These problems include the heat equation, Fitzhugh-Nagumo equation, and Burgers' equation. Each problem illustrates various aspects of the operation...
Steering random walks with kicked ultracold atoms
NASA Astrophysics Data System (ADS)
Weiß, Marcel; Groiseau, Caspar; Lam, W. K.; Burioni, Raffaella; Vezzani, Alessandro; Summy, Gil S.; Wimberger, Sandro
2015-09-01
The kicking sequence of the atom-optics kicked rotor at quantum resonance can be interpreted as a quantum random walk in momentum space. We show how such a walk can become the basis for nontrivial classical walks by applying a random sequence of intensities and phases of the kicking lattice chosen according to a probability distribution. This distribution converts on average into the final momentum distribution of the kicked atoms. In particular, it is shown that a power-law distribution for the kicking strengths results in a Lévy walk in momentum space and in a power law with the same exponent in the averaged momentum distribution. Furthermore, we investigate the stability of our predictions in the context of a realistic experiment with Bose-Einstein condensates.
Epidemic spreading driven by biased random walks
NASA Astrophysics Data System (ADS)
Pu, Cunlai; Li, Siyuan; Yang, Jian
2015-08-01
Random walk is one of the basic mechanisms of many network-related applications. In this paper, we study the dynamics of epidemic spreading driven by biased random walks in complex networks. In our epidemic model, infected nodes send out infection packets by biased random walks to their neighbor nodes, and this causes the infection of susceptible nodes that receive the packets. Infected nodes recover from the infection at a constant rate ?, and will not be infected again after recovery. We obtain the largest instantaneous number of infected nodes and the largest number of ever-infected nodes respectively, by tuning the parameter ? of the biased random walks. Simulation results on model and real-world networks show that spread of the epidemic becomes intense and widespread with increase of either delivery capacity of infected nodes, average node degree, or homogeneity of node degree distribution.
Walking for health in adolescent girls
MacDonald, Mhairi Jane
2014-07-04
Research has highlighted that adolescent girls are insufficiently active which has serious implications for their current and future health. Walking is recognised as an effective way of implementing regular, health ...
Care and Operation of Walk-Ins.
ERIC Educational Resources Information Center
Bauer, James M.
1979-01-01
Problems of owners who use their walk-in coolers and freezers only part of the year demand special consideration. Proper techniques for startup, operation, and shutdown must be used to guarantee efficient, inexpensive operation. (Author)
Network Discovery by Generalized Random Walks
A. Asztalos; Z. Toroczkai
2010-08-30
We investigate network exploration by random walks defined via stationary and adaptive transition probabilities on large graphs. We derive an exact formula valid for arbitrary graphs and arbitrary walks with stationary transition probabilities (STP), for the average number of discovered edges as function of time. We show that for STP walks site and edge exploration obey the same scaling $\\sim n^{\\lambda}$ as function of time $n$. Therefore, edge exploration on graphs with many loops is always lagging compared to site exploration, the revealed graph being sparse until almost all nodes have been discovered. We then introduce the Edge Explorer Model, which presents a novel class of adaptive walks, that perform faithful network discovery even on dense networks.
Real time visualization of quantum walk
Miyazaki, Akihide; Hamada, Shinji; Sekino, Hideo
2014-02-20
Time evolution of quantum particles like electrons is described by time-dependent Schrödinger equation (TDSE). The TDSE is regarded as the diffusion equation of electrons with imaginary diffusion coefficients. And the TDSE is solved by quantum walk (QW) which is regarded as a quantum version of a classical random walk. The diffusion equation is solved in discretized space/time as in the case of classical random walk with additional unitary transformation of internal degree of freedom typical for quantum particles. We call the QW for solution of the TDSE a Schrödinger walk (SW). For observation of one quantum particle evolution under a given potential in atto-second scale, we attempt a successive computation and visualization of the SW. Using Pure Data programming, we observe the correct behavior of a probability distribution under the given potential in real time for observers of atto-second scale.
Mesonic spectroscopy of minimal walking technicolor
Del Debbio, Luigi; Lucini, Biagio; Patella, Agostino; Pica, Claudio; Rago, Antonio
2010-07-01
We investigate the structure and the novel emerging features of the mesonic nonsinglet spectrum of the minimal walking technicolor theory. Precision measurements in the nonsinglet pseudoscalar and vector channels are compared to the expectations for an IR-conformal field theory and a QCD-like theory. Our results favor a scenario in which minimal walking technicolor is (almost) conformal in the infrared, while spontaneous chiral symmetry breaking seems less plausible.
Momentum Dynamics of One Dimensional Quantum Walks
Ian Fuss; Langord B. White; Peter J. Sherman; Sanjeev Naguleswaran
2006-05-24
We derive the momentum space dynamic equations and state functions for one dimensional quantum walks by using linear systems and Lie group theory. The momentum space provides an analytic capability similar to that contributed by the z transform in discrete systems theory. The state functions at each time step are expressed as a simple sum of three Chebyshev polynomials. The functions provide an analytic expression for the development of the walks with time.
Standardized Questionnaires of Walking & Bicycling Database
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.
Quantum Random Walks Hit Exponentially Faster
Julia Kempe
2002-05-14
We show that the hitting time of the discrete time quantum random walk on the n-bit hypercube from one corner to its opposite is polynomial in n. This gives the first exponential quantum-classical gap in the hitting time of discrete quantum random walks. We provide the framework for quantum hitting time and give two alternative definitions to set the ground for its study on general graphs. We then give an application to random routing.
Calcaneal loading during walking and running
NASA Technical Reports Server (NTRS)
Giddings, V. L.; Beaupre, G. S.; Whalen, R. T.; Carter, D. R.
2000-01-01
PURPOSE: This study of the foot uses experimentally measured kinematic and kinetic data with a numerical model to evaluate in vivo calcaneal stresses during walking and running. METHODS: External ground reaction forces (GRF) and kinematic data were measured during walking and running using cineradiography and force plate measurements. A contact-coupled finite element model of the foot was developed to assess the forces acting on the calcaneus during gait. RESULTS: We found that the calculated force-time profiles of the joint contact, ligament, and Achilles tendon forces varied with the time-history curve of the moment about the ankle joint. The model predicted peak talocalcaneal and calcaneocuboid joint loads of 5.4 and 4.2 body weights (BW) during walking and 11.1 and 7.9 BW during running. The maximum predicted Achilles tendon forces were 3.9 and 7.7 BW for walking and running. CONCLUSIONS: Large magnitude forces and calcaneal stresses are generated late in the stance phase, with maximum loads occurring at approximately 70% of the stance phase during walking and at approximately 60% of the stance phase during running, for the gait velocities analyzed. The trajectories of the principal stresses, during both walking and running, corresponded to each other and qualitatively to the calcaneal trabecular architecture.
Federal Register 2010, 2011, 2012, 2013, 2014
2011-11-18
...Walk National Historic Trail Feasibility Study/Abbreviated Final Environmental...Walk National Historic Trail Feasibility Study...Walk National Historic Trail Feasibility Study, prepared by National...
NASA Astrophysics Data System (ADS)
Whittaker, William; Dowling, Kevin
1994-03-01
Carnegie Mellon University's Autonomous Planetary Exploration Program (APEX) is currently building the Daedalus robot; a system capable of performing extended autonomous planetary exploration missions. Extended autonomy is an important capability because the continued exploration of the Moon, Mars and other solid bodies within the solar system will probably be carried out by autonomous robotic systems. There are a number of reasons for this - the most important of which are the high cost of placing a man in space, the high risk associated with human exploration and communication delays that make teleoperation infeasible. The Daedalus robot represents an evolutionary approach to robot mechanism design and software system architecture. Daedalus incorporates key features from a number of predecessor systems. Using previously proven technologies, the Apex project endeavors to encompass all of the capabilities necessary for robust planetary exploration. The Ambler, a six-legged walking machine was developed by CMU for demonstration of technologies required for planetary exploration. In its five years of life, the Ambler project brought major breakthroughs in various areas of robotic technology. Significant progress was made in: mechanism and control, by introducing a novel gait pattern (circulating gait) and use of orthogonal legs; perception, by developing sophisticated algorithms for map building; and planning, by developing and implementing the Task Control Architecture to coordinate tasks and control complex system functions. The APEX project is the successor of the Ambler project.
Holographic Walking from Tachyon DBI
David Kutasov; Jennifer Lin; Andrei Parnachev
2012-03-13
We use holography to study Conformal Phase Transitions, which are believed to be realized in four dimensional QCD and play an important role in walking technicolor models of electroweak symmetry breaking. At strong coupling they can be modeled by the non-linear dynamics of a tachyonic scalar field with mass close to the Breitenlohner-Freedman bound in anti de Sitter spacetime. Taking the action for this field to have a Tachyon-Dirac-Born-Infeld form gives rise to models that resemble hard and soft wall AdS/QCD, with a dynamically generated wall. For hard wall models, the highly excited spectrum has the KK form m_n ~ n; in the soft wall case we exhibit potentials with m_n ~ n^\\alpha, 0<\\alpha\\leq1/2. We investigate the finite temperature phase structure and find first or second order symmetry restoration transitions, depending on the behavior of the potential near the origin of field space.
NASA Technical Reports Server (NTRS)
Whittaker, William; Dowling, Kevin
1994-01-01
Carnegie Mellon University's Autonomous Planetary Exploration Program (APEX) is currently building the Daedalus robot; a system capable of performing extended autonomous planetary exploration missions. Extended autonomy is an important capability because the continued exploration of the Moon, Mars and other solid bodies within the solar system will probably be carried out by autonomous robotic systems. There are a number of reasons for this - the most important of which are the high cost of placing a man in space, the high risk associated with human exploration and communication delays that make teleoperation infeasible. The Daedalus robot represents an evolutionary approach to robot mechanism design and software system architecture. Daedalus incorporates key features from a number of predecessor systems. Using previously proven technologies, the Apex project endeavors to encompass all of the capabilities necessary for robust planetary exploration. The Ambler, a six-legged walking machine was developed by CMU for demonstration of technologies required for planetary exploration. In its five years of life, the Ambler project brought major breakthroughs in various areas of robotic technology. Significant progress was made in: mechanism and control, by introducing a novel gait pattern (circulating gait) and use of orthogonal legs; perception, by developing sophisticated algorithms for map building; and planning, by developing and implementing the Task Control Architecture to coordinate tasks and control complex system functions. The APEX project is the successor of the Ambler project.
Infinite densities for Lévy walks
NASA Astrophysics Data System (ADS)
Rebenshtok, A.; Denisov, S.; Hänggi, P.; Barkai, E.
2014-12-01
Motion of particles in many systems exhibits a mixture between periods of random diffusive-like events and ballistic-like motion. In many cases, such systems exhibit strong anomalous diffusion, where low-order moments <|x (t ) |q> with q below a critical value 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.
Infinite densities for Lévy walks.
Rebenshtok, A; Denisov, S; Hänggi, P; Barkai, E
2014-12-01
Motion of particles in many systems exhibits a mixture between periods of random diffusive-like events and ballistic-like motion. In many cases, such systems exhibit strong anomalous diffusion, where low-order moments ?|x(t)|(q)? with q below a critical value q(c) exhibit diffusive scaling while for q>q(c) a ballistic scaling emerges. The mixed dynamics constitutes a theoretical challenge since it does not fall into a unique category of motion, e.g., the known diffusion equations and central limit theorems fail to describe both aspects. In this paper we resolve this problem by resorting to the concept of infinite density. Using the widely applicable Lévy walk model, we find a general expression for the corresponding non-normalized density which is fully determined by the particles velocity distribution, the anomalous diffusion exponent ?, and the diffusion coefficient K(?). We explain how infinite densities play a central role in the description of dynamics of a large class of physical processes and discuss how they can be evaluated from experimental or numerical data. PMID:25615072
Torque-stiffness-controlled dynamic walking with central pattern generators.
Huang, Yan; Vanderborght, Bram; Van Ham, Ronald; Wang, Qining
2014-12-01
Walking behavior is modulated by controlling joint torques in most existing passivity-based bipeds. Controlled Passive Walking with adaptable stiffness exhibits controllable natural motions and energy efficient gaits. In this paper, we propose torque-stiffness-controlled dynamic bipedal walking, which extends the concept of Controlled Passive Walking by introducing structured control parameters and a bio-inspired control method with central pattern generators. The proposed walking paradigm is beneficial in clarifying the respective effects of the external actuation and the internal natural dynamics. We present a seven-link biped model to validate the presented walking. Effects of joint torque and joint stiffness on gait selection, walking performance and walking pattern transitions are studied in simulations. The work in this paper develops a new solution of motion control of bipedal robots with adaptable stiffness and provides insights of efficient and sophisticated walking gaits of humans. PMID:25128320
Nordic walking practice might improve plantar pressure distribution.
Pérez-Soriano, Pedro; Llana-Belloch, Salvador; Martínez-Nova, Alfonso; Morey-Klapsing, G; Encarnación-Martínez, Alberto
2011-12-01
Nordic walking (NW), characterized by the use of two walking poles, is becoming increasingly popular (Morgulec-Adamowicz, Marszalek, & Jagustyn, 2011). We studied walking pressure patterns of 20 experienced and 30 beginner Nordic walkers. Plantar pressures from nine foot zones were measured during trials performed at two walking speeds (preferred and 20% faster), and under two walking conditions (NW vs. normal walking). In comparison to normal walking, NW experience led to a significant (p < .05) pressure reduction of about 50% on the central metatarsals. No significant increases were detected in other foot regions. The differences between experienced and beginners during normal walking including a 40% pressure reduction on the metatarsal area, suggests that regular NW practice might also have a beneficial effect on plantar pressure when walking without poles. PMID:22276400
The CyberWalk Platform: Human-Machine Interaction Enabling Unconstrained Walking through VR
The CyberWalk Platform: Human-Machine Interaction Enabling Unconstrained Walking through VR P years, Virtual Reality (VR) has become incre- asingly realistic and immersive. Both the visual and audi virtual environments using a mouse or a joystick. Of course, the most natural way to navigate through VR
Framework for discrete-time quantum walks and a symmetric walk on a binary tree
Zlatko Dimcovic; Daniel Rockwell; Ian Milligan; Robert M. Burton; Thinh Nguyen; Yevgeniy Kovchegov
2011-09-29
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.
Framework for discrete-time quantum walks and a symmetric walk on a binary tree
Dimcovic, Zlatko; Rockwell, Daniel; Milligan, Ian; Burton, Robert M.; Kovchegov, Yevgeniy; Nguyen, Thinh
2011-09-15
We formulate a framework for discrete-time quantum walks, motivated by classical random walks with memory. We present a specific representation of the classical walk with memory 2, on which this is based. The framework has no need for coin spaces, it imposes no constraints on the evolution operator other than unitarity, and is unifying of other approaches. As an example we construct a symmetric discrete-time quantum walk on the semi-infinite binary tree. The generating function of the amplitude at the root is computed in closed form, as a function of time and the initial level n in the tree, and we find the asymptotic and a full numerical solution for the amplitude. It exhibits a sharp interference peak and a power-law tail, as opposed to the exponentially decaying tail of a broadly peaked distribution of the classical symmetric random walk on a binary tree. The probability peak is orders of magnitude larger than it is for the classical walk (already at small n). The quantum walk shows a polynomial algorithmic speedup in n over the classical walk, which we conjecture to be of the order 2/3, based on strong trends in data.
New simple virtual walking method walking on the spot L. Yan, R.S. Allison
Allison, Robert
the virtual environment and provides the ability to study human locomotion and navigation in a CAVE. Introduction and Motivation Presentation of effective virtual environments in CAVEs, and other projectorNew simple virtual walking method walking on the spot L. Yan, R.S. Allison York University, 4700
Kinematic evaluation of virtual walking trajectories.
Cirio, Gabriel; Olivier, Anne-Hélène; Marchal, Maud; Pettré, Julien
2013-04-01
Virtual walking, a fundamental task in Virtual Reality (VR), is greatly influenced by the locomotion interface being used, by the specificities of input and output devices, and by the way the virtual environment is represented. No matter how virtual walking is controlled, the generation of realistic virtual trajectories is absolutely required for some applications, especially those dedicated to the study of walking behaviors in VR, navigation through virtual places for architecture, rehabilitation and training. Previous studies focused on evaluating the realism of locomotion trajectories have mostly considered the result of the locomotion task (efficiency, accuracy) and its subjective perception (presence, cybersickness). Few focused on the locomotion trajectory itself, but in situation of geometrically constrained task. In this paper, we study the realism of unconstrained trajectories produced during virtual walking by addressing the following question: did the user reach his destination by virtually walking along a trajectory he would have followed in similar real conditions? To this end, we propose a comprehensive evaluation framework consisting on a set of trajectographical criteria and a locomotion model to generate reference trajectories. We consider a simple locomotion task where users walk between two oriented points in space. The travel path is analyzed both geometrically and temporally in comparison to simulated reference trajectories. In addition, we demonstrate the framework over a user study which considered an initial set of common and frequent virtual walking conditions, namely different input devices, output display devices, control laws, and visualization modalities. The study provides insight into the relative contributions of each condition to the overall realism of the resulting virtual trajectories. PMID:23428452
Quantum walks on two kinds of two-dimensional models
Dan Li; Michael Mc Gettrick; Wei-Wei Zhang; Ke-Jia Zhang
2015-01-08
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.
Mean first return time for random walks on weighted networks
NASA Astrophysics Data System (ADS)
Jing, Xing-Li; Ling, Xiang; Long, Jiancheng; Shi, Qing; Hu, Mao-Bin
2015-11-01
Random walks on complex networks are of great importance to understand various types of phenomena in real world. In this paper, two types of biased random walks on nonassortative weighted networks are studied: edge-weight-based random walks and node-strength-based random walks, both of which are extended from the normal random walk model. Exact expressions for stationary distribution and mean first return time (MFRT) are derived and examined by simulation. The results will be helpful for understanding the influences of weights on the behavior of random walks.
Nordic walking improves mobility in Parkinson's disease.
van Eijkeren, Frank J M; Reijmers, Ruud S J; Kleinveld, Mirjam J; Minten, Angret; Bruggen, Jan Pieter Ter; Bloem, Bastiaan R
2008-11-15
Nordic walking may improve mobility in Parkinson's disease (PD). Here, we examined whether the beneficial effects persist after the training period. We included 19 PD patients [14 men; mean age 67.0 years (range 58-76); Hoehn and Yahr stage range 1-3] who received a 6-week Nordic walking exercise program. Outcome was assessed prior to training (T1), immediately after the training period (T2) and-in a subgroup of 9 patients--5 months after training (T3). At T2, we observed a significant improvement in timed 10-m walking, the timed get-up-and-go-test (TUG), the 6-min walking test and quality of life (PDQ-39). All treatment effects persisted at T3. Compliance was excellent, and there were no adverse effects. These preliminary findings suggest that Nordic walking could provide a safe, effective, and enjoyable way to reduce physical inactivity in PD and to improve the quality of life. A large randomized clinical trial now appears justified. PMID:18816697
Quantum Walks on the Line with Phase Parameters
NASA Astrophysics Data System (ADS)
Villagra, Marcos; Nakanishi, Masaki; Yamashita, Shigeru; Nakashima, Yasuhiko
In this paper, a study on discrete-time coined quantum walks on the line is presented. Clear mathematical foundations are still lacking for this quantum walk model. As a step toward this objective, the following question is being addressed: Given a graph, what is the probability that a quantum walk arrives at a given vertex after some number of steps? This is a very natural question, and for random walks it can be answered by several different combinatorial arguments. For quantum walks this is a highly non-trivial task. Furthermore, this was only achieved before for one specific coin operator (Hadamard operator) for walks on the line. Even considering only walks on lines, generalizing these computations to a general SU(2) coin operator is a complex task. The main contribution is a closed-form formula for the amplitudes of the state of the walk (which includes the question above) for a general symmetric SU(2) operator for walks on the line. To this end, a coin operator with parameters that alters the phase of the state of the walk is defined. Then, closed-form solutions are computed by means of Fourier analysis and asymptotic approximation methods. We also present some basic properties of the walk which can be deducted using weak convergence theorems for quantum walks. In particular, the support of the induced probability distribution of the walk is calculated. Then, it is shown how changing the parameters in the coin operator affects the resulting probability distribution.
Steering random walks with kicked ultracold atoms
Marcel Weiß; Caspar Groiseau; W. K. Lam; Raffaella Burioni; Alessandro Vezzani; Gil S. Summy; Sandro Wimberger
2015-06-27
A kicking sequence of the atom optics kicked rotor at quantum resonance can be interpreted as a quantum random walk in momentum space. We show how to steer such a random walk by applying a random sequence of intensities and phases of the kicking lattice chosen according to a probability distribution. This distribution converts on average into the final momentum distribution of the kicked atoms. In particular, it is shown that a power-law distribution for the kicking strengths results in a L\\'evy walk in momentum space and in a power-law with the same exponent in the averaged momentum distribution. Furthermore, we investigate the stability of our predictions in the context of a realistic experiment with Bose-Einstein condensates.
Exploring Temporal Networks with Greedy Walks
Saramaki, Jari
2015-01-01
Temporal networks come with a wide variety of heterogeneities, from burstiness of event sequences to correlations between timingsof node and link activations. In this paper, we set to explore the latter by using greedy walks as probes of temporal network structure. Given a temporal network (a sequence of contacts), greedy walks proceed from node to node by always following the first available contact. Because of this, their structure is particularly sensitive to temporal-topological patterns involving repeated contacts between sets of nodes. This becomes evident in their small coverage per step as compared to a temporal reference model -- in empirical temporal networks, greedy walks often get stuck within small sets of nodes because of correlated contact patterns. While this may also happen in static networks that have pronounced community structure, the use of the temporal reference model takes the underlying static network structure out of the equation and indicates that there is a purely temporal reason fo...
Fast Scramblers, Democratic Walks and Information Fields
Javier M. Magan
2015-07-09
We study a family of weighted random walks on complete graphs. These `democratic walks' turn out to be explicitly solvable, and we find the hierarchy window for which the characteristic time scale saturates the so-called fast scrambling conjecture. We show that these democratic walks describe well the properties of information spreading in systems in which every degree of freedom interacts with every other degree of freedom, such as Matrix or infinite range models. The argument is based on the analysis of suitably defined `Information fields' ($\\mathcal{I}$), which are shown to evolve stochastically towards stationarity due to unitarity of the microscopic model. The model implies that in democratic systems, stabilization of one subsystem is equivalent to global scrambling. We use these results to study scrambling of infalling perturbations in black hole backgrounds, and argue that the near horizon running coupling constants are connected to entanglement evolution of single particle perturbations in democratic systems.
Universal quantum computation by discontinuous quantum walk
Underwood, Michael S.; Feder, David L.
2010-10-15
Quantum walks are the quantum-mechanical analog of random walks, in which a quantum ''walker'' evolves between initial and final states by traversing the edges of a graph, either in discrete steps from node to node or via continuous evolution under the Hamiltonian furnished by the adjacency matrix of the graph. We present a hybrid scheme for universal quantum computation in which a quantum walker takes discrete steps of continuous evolution. This ''discontinuous'' quantum walk employs perfect quantum-state transfer between two nodes of specific subgraphs chosen to implement a universal gate set, thereby ensuring unitary evolution without requiring the introduction of an ancillary coin space. The run time is linear in the number of simulated qubits and gates. The scheme allows multiple runs of the algorithm to be executed almost simultaneously by starting walkers one time step apart.
Nested Quantum Walks with Quantum Data Structures
Stacey Jeffery; Robin Kothari; Frederic Magniez
2012-10-03
We develop a new framework that extends the quantum walk framework of Magniez, Nayak, Roland, and Santha, by utilizing the idea of quantum data structures to construct an efficient method of nesting quantum walks. Surprisingly, only classical data structures were considered before for searching via quantum walks. The recently proposed learning graph framework of Belovs has yielded improved upper bounds for several problems, including triangle finding and more general subgraph detection. We exhibit the power of our framework by giving a simple explicit constructions that reproduce both the $O(n^{35/27})$ and $O(n^{9/7})$ learning graph upper bounds (up to logarithmic factors) for triangle finding, and discuss how other known upper bounds in the original learning graph framework can be converted to algorithms in our framework. We hope that the ease of use of this framework will lead to the discovery of new upper bounds.
Humanoid robot Lola: design and walking control.
Buschmann, Thomas; Lohmeier, Sebastian; Ulbrich, Heinz
2009-01-01
In this paper we present the humanoid robot LOLA, its mechatronic hardware design, simulation and real-time walking control. The goal of the LOLA-project is to build a machine capable of stable, autonomous, fast and human-like walking. LOLA is characterized by a redundant kinematic configuration with 7-DoF legs, an extremely lightweight design, joint actuators with brushless motors and an electronics architecture using decentralized joint control. Special emphasis was put on an improved mass distribution of the legs to achieve good dynamic performance. Trajectory generation and control aim at faster, more flexible and robust walking. Center of mass trajectories are calculated in real-time from footstep locations using quadratic programming and spline collocation methods. Stabilizing control uses hybrid position/force control in task space with an inner joint position control loop. Inertial stabilization is achieved by modifying the contact force trajectories. PMID:19665558
Swarming bacteria migrate by Lévy Walk
Ariel, Gil; Rabani, Amit; Benisty, Sivan; Partridge, Jonathan D.; Harshey, Rasika M.; Be'er, Avraham
2015-01-01
Individual swimming bacteria are known to bias their random trajectories in search of food and to optimize survival. The motion of bacteria within a swarm, wherein they migrate as a collective group over a solid surface, is fundamentally different as typical bacterial swarms show large-scale swirling and streaming motions involving millions to billions of cells. Here by tracking trajectories of fluorescently labelled individuals within such dense swarms, we find that the bacteria are performing super-diffusion, consistent with Lévy walks. Lévy walks are characterized by trajectories that have straight stretches for extended lengths whose variance is infinite. The evidence of super-diffusion consistent with Lévy walks in bacteria suggests that this strategy may have evolved considerably earlier than previously thought. PMID:26403719
Quantum random-walk search algorithm
Shenvi, Neil; Whaley, K. Birgitta; Kempe, Julia
2003-05-01
Quantum random walks on graphs have been shown to display many interesting properties, including exponentially fast hitting times when compared with their classical counterparts. However, it is still unclear how to use these novel properties to gain an algorithmic speedup over classical algorithms. In this paper, we present a quantum search algorithm based on the quantum random-walk architecture that provides such a speedup. It will be shown that this algorithm performs an oracle search on a database of N items with O({radical}(N)) calls to the oracle, yielding a speedup similar to other quantum search algorithms. It appears that the quantum random-walk formulation has considerable flexibility, presenting interesting opportunities for development of other, possibly novel quantum algorithms.
Swarming bacteria migrate by Lévy Walk
NASA Astrophysics Data System (ADS)
Ariel, Gil; Rabani, Amit; Benisty, Sivan; Partridge, Jonathan D.; Harshey, Rasika M.; Be'Er, Avraham
2015-09-01
Individual swimming bacteria are known to bias their random trajectories in search of food and to optimize survival. The motion of bacteria within a swarm, wherein they migrate as a collective group over a solid surface, is fundamentally different as typical bacterial swarms show large-scale swirling and streaming motions involving millions to billions of cells. Here by tracking trajectories of fluorescently labelled individuals within such dense swarms, we find that the bacteria are performing super-diffusion, consistent with Lévy walks. Lévy walks are characterized by trajectories that have straight stretches for extended lengths whose variance is infinite. The evidence of super-diffusion consistent with Lévy walks in bacteria suggests that this strategy may have evolved considerably earlier than previously thought.
Swarming bacteria migrate by Lévy Walk.
Ariel, Gil; Rabani, Amit; Benisty, Sivan; Partridge, Jonathan D; Harshey, Rasika M; Be'er, Avraham
2015-01-01
Individual swimming bacteria are known to bias their random trajectories in search of food and to optimize survival. The motion of bacteria within a swarm, wherein they migrate as a collective group over a solid surface, is fundamentally different as typical bacterial swarms show large-scale swirling and streaming motions involving millions to billions of cells. Here by tracking trajectories of fluorescently labelled individuals within such dense swarms, we find that the bacteria are performing super-diffusion, consistent with Lévy walks. Lévy walks are characterized by trajectories that have straight stretches for extended lengths whose variance is infinite. The evidence of super-diffusion consistent with Lévy walks in bacteria suggests that this strategy may have evolved considerably earlier than previously thought. PMID:26403719
Evaluation of book backpack load during walking.
Wang, Y; Pascoe, D D; Weimar, W
2001-07-15
This investigation evaluated accumulated mean and peak impact forces per stride and per metre associated with two book backpack loads and two cadences during single and double support phases of walking. Thirty college participants randomly performed three trials while either walking a self-selected cadence or fixed cadence without (empty pack) or with a load (15% body mass) carried in a bookbag. The fixed cadence (55.5 steps/min) was regulated by a metronome. A computerized Kistler force platform system (phase-locked timing device) recorded (200 Hz) three-dimensional reaction forces, impulses, and time in single and double support phases. A Panasonic video camera AG-450 was set perpendicular to the plane of walking motion to film (60 Hz) the walking pattern from which stride length and selected kinematic data were determined. Repeated measure ANOVA (p<0.05) determined differences of loads and cadences in walking. Accumulated force was evaluated as impulses per stride and impulses per metre (stress index). When carrying the 15% load, there was a decrease in speed, a decrease in single support time (SST), and an increase in double support time (DST). The impulses per stride significantly increased in DST, and significantly decrease in SST. When impulses were analysed per metre, the stress index signficantly increased in DST, but not during SST. These differences in SST may be important when load stress is applied to the single support leg/foot in any given distance of walking. While stride analysis identifies accumulative forces resulting from varying stride lengths, the stress index provides a standardized measure per metre of the accumulative forces that negate the variances of individual stride lengths, and the index measure can easily represent data for any given distance traversed. PMID:11560366
The pilot-wave dynamics of walking droplets in confinement
Harris, Daniel Martin
2015-01-01
A decade ago, Yves Couder and coworkers discovered that millimetric droplets can walk on a vibrated fluid bath, and that these walking droplets or "walkers" display several features reminiscent of quantum particles. We ...
Paralyzed Man Walks Using Technology That Bypasses Spinal Cord
... html Paralyzed Man Walks Using Technology That Bypasses Spinal Cord Brain signals travel through a computer that sends ... system like this might help people with a spinal cord injury regain some ability to walk, the researchers ...
A model of muscle-tendon function in human walking
Endo, Ken, Ph. D. Massachusetts Institute of Technology
2012-01-01
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 ...
Exploring Complex Graphs by Random Walks
NASA Astrophysics Data System (ADS)
Tadi?, Bosiljka
2003-04-01
We present an algorithm to grow a graph with scale-free structure of {\\it in-} and {\\it out-links} and variable wiring diagram in the class of the world-wide Web. We then explore the graph by intentional random walks using local next-near-neighbor search algorithm to navigate through the graph. The topological properties such as betweenness are determined by an ensemble of independent walkers and efficiency of the search is compared on three different graph topologies. In addition we simulate interacting random walks which are created by given rate and navigated in parallel, representing transport with queueing of information packets on the graph.
Quantum Persistence: A Random Walk Scenario
Sanchari Goswami; Parongama Sen; Arnab Das
2010-01-28
In this paper we extend the concept of persistence, well defined for classical stochastic dynamics, to the context of quantum dynamics. We demonstrate the idea via quantum random walk and a successive measurement scheme, where persistence is defined as the time during which a given site remains unvisited by the walker. We also investigated the behavior of related quantities, e.g., the first-passage time and the succession probability (newly defined), etc. The study reveals power law scaling behavior of these quantities with new exponents. Comparable features of the classical and the quantum walks are discussed.
Quantum persistence: a random-walk scenario.
Goswami, Sanchari; Sen, Parongama; Das, Arnab
2010-02-01
In this paper we extend the concept of persistence, well defined for classical stochastic dynamics, to the context of quantum dynamics. We demonstrate the idea via quantum random walk and a successive measurement scheme, where persistence is defined as the time during which a given site remains unvisited by the walker. We also investigated the behavior of related quantities, e.g., the first-passage time and the succession probability (newly defined), etc. The study reveals power-law scaling behavior of these quantities with new exponents. Comparable features of the classical and the quantum walks are discussed. PMID:20365544
Interacting growth walk on a honeycomb lattice
NASA Astrophysics Data System (ADS)
Narasimhan, S. L.; Sridhar, V.; Murthy, K. P. N.
2003-03-01
The interacting growth walk (IGW) is a kinetic algorithm proposed recently for generating long, lattice polymer configurations. The growth process in IGW is tuned by a parameter called the growth temperature TG=1/( kB?G). In this paper we consider IGW on a honeycomb lattice. We take the non-bonded nearest neighbour contact energy as ?=-1. We show that at ?G=0, IGW algorithm generates a canonical ensemble of interacting self-avoiding walks at ?= ??(? G=0)= ln(2) . However for ?G>0, IGW generates an ensemble of polymer configurations most of which are in equilibrium at ?= ??(? G) . The remaining ones are frozen in ‘non-equilibrium’ configurations.
Spectral solution of delayed random walks.
Bhat, H S; Kumar, N
2012-10-01
We develop a spectral method for computing the probability density function for delayed random walks; for such problems, the method is exact to machine precision and faster than existing approaches. In conjunction with a step function approximation and the weak Euler-Maruyama discretization, the spectral method can be applied to nonlinear stochastic delay differential equations (SDDE). In essence, this means approximating the SDDE by a delayed random walk, which is then solved using the spectral method. We carry out tests for a particular nonlinear SDDE that show that this method captures the solution without the need for Monte Carlo sampling. PMID:23214645
Mall walking. An effective mental health intervention for older adults.
Travis, S S; Duncan, H H; McAuley, W J
1996-08-01
1. Traditional goals of health promotion and disease prevention are actually secondary factors in many walkers' motivations for mall-walking activity. 2. The routine of mall walking and the social relationships they form keep older adults going back to the mall. 3. Successful mall-walking program directors are beginning to understand the need to emphasize the social benefits of participating in a mall-walking group as much, if not more than, the health benefits of regular exercise. PMID:8856603
Fifteen-minute consultation: A child with toe walking.
Sivaramakrishnan, Shobha; Seal, Arnab
2015-10-01
Toe walking is a common developmental phenomenon in young children. It is usually benign and self-limiting. Toe walking can be a presenting sign of some serious underlying disorders and idiopathic toe walking is a diagnosis of exclusion. Persistent toe walking can lead to limited ankle dorsiflexion which may cause functional problems. Specific interventions depend on underlying cause and may range from verbal reinforcement to serial casting and surgery. PMID:25855215
Walking and the Preservation of Cognitive Function in Older Populations
ERIC Educational Resources Information Center
Prohaska, Thomas R.; Eisenstein, Amy R.; Satariano, William A.; Hunter, Rebecca; Bayles, Constance M.; Kurtovich, Elaine; Kealey, Melissa; Ivey, Susan L.
2009-01-01
Purpose: This cross-sectional study takes a unique look at the association between patterns of walking and cognitive functioning by examining whether older adults with mild cognitive impairment differ in terms of the community settings where they walk and the frequency, intensity, or duration of walking. Design and Methods: The sample was based on…
Control of Physicallybased Simulated Walking Joseph F. Laszlo
Toronto, University of
Control of PhysicallyÂbased Simulated Walking Joseph F. Laszlo Michiel van de Panne Eugene Fiume Department of Computer Science University of Toronto 1 Abstract Walking is a deceptively simple behaviour actions to control a walk. This work describes a technique which adds closedÂ loop control to open
Synthesis of Controllers for Stylized Planar Bipedal Walking
Panne, M. van de
Synthesis of Controllers for Stylized Planar Bipedal Walking Dana Sharon, and Michiel van de Panne,van}@cs.ubc.ca Abstract-- We present a method for computing controllers for stable planar-biped walking gaits that follow of a simulated motion from a desired target motion. We demonstrate simulated bipedal walks having user
A Proposal for Data Collection: Establishing Pedestrian Walking Speeds
Bertini, Robert L.
A Proposal for Data Collection: Establishing Pedestrian Walking Speeds Submitted to: Karen Aspelin on Uniform Traffic Control Devices (MUTCD) currently recommends that a normal pedestrian walking speed of 4 been a select number of studies on pedestrian walking speeds in the past (see Laplante and Kaeser, ITE
NON-PERTURBATIVE APPROACH TO RANDOM WALK IN MARKOVIAN ENVIRONMENT.
Liverani, Carlangelo
NON-PERTURBATIVE APPROACH TO RANDOM WALK IN MARKOVIAN ENVIRONMENT. DMITRY DOLGOPYAT AND CARLANGELO LIVERANI Abstract. We prove the CLT for a random walk in a dynamical environment where the states of the environment at different sites are independent Markov chains. 1. Introduction The study of random walk
The 'passive dynamic walking machine' used in the experiments.
Collins, Steven H.
gave humans energy advantage Did apes start upright walking in trees? Exercise no walk in the park Ants neurological disorders, such as Parkinson's disease and cerebral palsy, cause constrained or opposite arm motion. This abnormal movement negatively affects sufferers' walking balance and energy expenditure
Correct Software Synthesis for Stable Speed-Controlled Robotic Walking
Ames, Aaron
walking on bipedal robots, however, is a challenging control problem. To compose walking with more varied and autonomous robot actions, the robot must safely and reliably transition between different walking behaviors by implementing Human-Inspired control of bipedal robots using a supervised Motion Grammar, automatically
Online Appendix to: CyberWalk: Enabling Unconstrained Omnidirectional
De Luca, Alessandro
Online Appendix to: CyberWalk: Enabling Unconstrained Omnidirectional Walking through Virtual The requirements for enabling real walking through a virtual environment (VE) depend on its size. For small VEs-mounted display (HMD) or CAVE-like projection system, can be updated according to the measured head movements
The Not-so-Random Drunkard's Walk
ERIC Educational Resources Information Center
Ehrhardt, George
2013-01-01
This dataset contains the results of a quasi-experiment, testing Karl Pearson's "drunkard's walk" analogy for an abstract random walk. Inspired by the alternate hypothesis that drunkards stumble to the side of their dominant hand, it includes data on intoxicated test subjects walking a 10' line. Variables include: the…
Random walk with shrinking steps P. L. Krapivskya)
Redner, Sidney
Random walk with shrinking steps P. L. Krapivskya) and S. Rednerb) Center for BioDynamics, Center April 2003; accepted 17 October 2003 We outline the properties of a symmetric random walk in one Teachers. DOI: 10.1119/1.1632487 I. INTRODUCTION This article discusses the properties of random walks
Random Walks and Orthogonal Functions Associated with Highly Symmetric Graphs
Stadler, Peter F.
Random Walks and Orthogonal Functions Associated with Highly Symmetric Graphs By Peter F. Stadler and random walks on such graphs is investigated. We use this relations to characterize the exponentially decaying autocorrelation functions along random walks on isotropic random fields defined on vertex
Random Walks with Jumps in Wireless Sensor Networks
Stavrakakis, Ioannis
Random Walks with Jumps in Wireless Sensor Networks Leonidas Tzevelekas University of Athens Greece Email: ltzev@di.uoa.gr Ioannis Stavrakakis University of Athens Greece Email: ioannis@di.uoa.gr Abstract--Random. In this work we propose the Random Walk with Jumps model as an improvement on the Random Walk without Jumps
Ladouceur, M; Barbeau, H
2000-06-01
This study was conducted to investigate the change in the kinematics and physiological cost of walking that occurs during training with functional electrical stimulation (FES)-assisted walking in persons with incomplete injuries. The main effect of FES-assisted walking was to change hip excursion and ankle dorsiflexion during swing and at foot contact, whereas training with FES-assisted walking changed the spatio-temporal parameters of walking (walking speed, cycle length and frequency as well as time in stance). The use of FES-assisted walking does not change the walking speed achieved during a 5-minute trial nor the physiological cost of walking but when combined with walking training, eight of the nine participants improved either their physiological cost index or their walking speed. It is concluded that FES-assisted walking changes the joint angular kinematic pattern of walking, but training is necessary to integrate these changes into functional gains. PMID:10853721
75 FR 185 - Energy Conservation Program: Test Procedures for Walk-In Coolers and Walk-In Freezers
Federal Register 2010, 2011, 2012, 2013, 2014
2010-01-04
...Pursuant to the Energy Policy and Conservation Act, as amended, the U.S. Department of Energy (DOE) is proposing test procedures for measuring the energy consumption of walk-in coolers and walk-in freezers (collectively ``walk-in equipment'' or ``walk- in(s)''), definitions to delineate the products covered by the test procedures, and provisions (including a sampling plan) for manufacturers to......
Searching via walking: How to find a marked clique of a complete graph using quantum walks
Hillery, Mark; Reitzner, Daniel; Buzek, Vladimir
2010-06-15
We show how a quantum walk can be used to find a marked edge or a marked complete subgraph of a complete graph. We employ a version of a quantum walk, the scattering walk, which lends itself to experimental implementation. The edges are marked by adding elements to them that impart a specific phase shift to the particle as it enters or leaves the edge. If the complete graph has N vertices and the subgraph has K vertices, the particle becomes localized on the subgraph in O(N/K) steps. This leads to a quantum search that is quadratically faster than a corresponding classical search. We show how to implement the quantum walk using a quantum circuit and a quantum oracle, which allows us to specify the resources needed for a quantitative comparison of the efficiency of classical and quantum searches--the number of oracle calls.
Joh, Kenneth; Chakrabarti, Sandip; Boarnet, Marlon G.; Woo, Ayoung
2015-07-10
Promoting walking travel is considered important for reducing automobile use and improving public health. Recent U.S. transportation policy has incentivized investments in alternative, more sustainable transportation modes ...
Collisions of Random Walks Martin T. Barlow
Barlow, Martin T.
at the same point, collide infinitely often a.s. We give a simple criterion in terms of Green functions by establishing a simple zero one law and a sufficient condition (in terms of Green functions) for infinite A recurrent graph G has the infinite collision property if two independent random walks on G, started
Validation of a Walking Behavior Measure
Gopalakrishnan, K.
Introduction Importance of measuring walking Importance and definition of validation Brief history and current these inferences. Evidence of validity should be judged based on the intended use of the data. #12;A Little History traditionally followed the conceptualization of validity in psychology measurement. "Test Standards" published
Sunspot random walk and 22-year variation
Love, Jeffrey J.; Rigler, E. Joshua
2012-01-01
We examine two stochastic models for consistency with observed long-term secular trends in sunspot number and a faint, but semi-persistent, 22-yr signal: (1) a null hypothesis, a simple one-parameter random-walk model of sunspot-number cycle-to-cycle change, and, (2) an alternative hypothesis, a two-parameter random-walk model with an imposed 22-yr alternating amplitude. The observed secular trend in sunspots, seen from solar cycle 5 to 23, would not be an unlikely result of the accumulation of multiple random-walk steps. Statistical tests show that a 22-yr signal can be resolved in historical sunspot data; that is, the probability is low that it would be realized from random data. On the other hand, the 22-yr signal has a small amplitude compared to random variation, and so it has a relatively small effect on sunspot predictions. Many published predictions for cycle 24 sunspots fall within the dispersion of previous cycle-to-cycle sunspot differences. The probability is low that the Sun will, with the accumulation of random steps over the next few cycles, walk down to a Dalton-like minimum. Our models support published interpretations of sunspot secular variation and 22-yr variation resulting from cycle-to-cycle accumulation of dynamo-generated magnetic energy.
Healthy Living Initiative: Running/Walking Club
ERIC Educational Resources Information Center
Stylianou, Michalis; Kulinna, Pamela Hodges; Kloeppel, Tiffany
2014-01-01
This study was grounded in the public health literature and the call for schools to serve as physical activity intervention sites. Its purpose was twofold: (a) to examine the daily distance covered by students in a before-school running/walking club throughout 1 school year and (b) to gain insights on the teachers perspectives of the club.…
Di, TG; Hillery, M.; Zubairy, M. Suhail
2004-01-01
We discuss a possible experimental scheme for the implementation of a quantum walk. The scheme is based on the passage of an atom inside a high-Q cavity. The chirality is characterized by the atomic states and the displacement is characterized...
A three-dimensional human walking model
NASA Astrophysics Data System (ADS)
Yang, Q. S.; Qin, J. W.; Law, S. S.
2015-11-01
A three-dimensional human bipedal walking model with compliant legs is presented in this paper. The legs are modeled with time-variant dampers, and the model is able to characterize the gait pattern of an individual using a minimal set of parameters. Feedback control, for both the forward and lateral movements, is implemented to regulate the walking performance of the pedestrian. The model provides an improvement over classic invert pendulum models. Numerical studies were undertaken to investigate the effects of leg stiffness and attack angle. Simulation results show that when walking at a given speed, increasing the leg stiffness with a constant attack angle results in a longer step length, a higher step frequency, a faster walking speed and an increase in both the peak vertical and lateral ground reaction forces. Increasing the attack angle with a constant leg stiffness results in a higher step frequency, a decrease in the step length, an increase in the total energy of the system and a decrease in both the peak vertical and lateral ground reaction forces.
Random matrices, nonbacktracking walks, and orthogonal polynomials
NASA Astrophysics Data System (ADS)
Sodin, Sasha
2007-12-01
Several well-known results from the random matrix theory, such as Wigner's law and the Marchenko-Pastur law, can be interpreted (and proved) in terms of nonbacktracking walks on a certain graph. Orthogonal polynomials with respect to the limiting spectral measure play a role in this approach.
Autonomous exoskeleton reduces metabolic cost of walking.
Mooney, Luke M; Rouse, Elliott J; Herr, Hugh M
2014-01-01
We developed an autonomous powered leg exoskeleton capable of providing large amounts of positive mechanical power to the wearer during powered plantarflexion phase of walking. The autonomous exoskeleton consisted of a winch actuator fasted to the shin which pulled on fiberglass struts attached to a boot. The fiberglass struts formed a rigid extension of the foot when the proximal end of the strut was pulled in forward by the winch actuator. This lightweight, geometric transmission allowed the electric winch actuator to efficiently produce biological levels of power at the ankle joint. The exoskeleton was powered and controlled by lithium polymer batteries and motor controller worn around the waist. Preliminary testing on two subjects walking at 1.4 m/s resulted in the exoskeleton reducing the metabolic cost of walking by 6-11% as compared to not wearing the device. The exoskeleton provided a peak mechanical power of over 180 W at each ankle (mean standard ± deviation) and an average positive mechanical power of 27 ± 1 W total to both ankles, while electrically using 75-89 W of electricity. The batteries (800 g) used in this experiment are estimated to be capable of providing this level of assistance for up to 7 km of walking. PMID:25570638
Pedometer accuracy in slow walking older adults.
Martin, Jessica B; Kr?, Katarina M; Mitchell, Emily A; Eng, Janice J; Noble, Jeremy W
2012-07-01
The purpose of this study was to determine pedometer accuracy during slow overground walking in older adults (Mean age = 63.6 years). A total of 18 participants (6 males, 12 females) wore 5 different brands of pedometers over 3 pre-set cadences that elicited walking speeds between 0.3 and 0.9 m/s and one self-selected cadence over 80 meters of indoor track. Pedometer accuracy decreased with slower walking speeds with mean percent errors across all devices combined of 56%, 40%, 19% and 9% at cadences of 50, 66, and 80 steps/min, and self selected cadence, respectively. Percent error ranged from 45.3% for Omron HJ105 to 66.9% for Yamax Digiwalker 200. Due to the high level of error across the slowest cadences of all 5 devices, the use of pedometers to monitor step counts in healthy older adults with slower gait speeds is problematic. Further research is required to develop pedometer mechanisms that accurately measure steps at slower walking speeds. PMID:24795762
The physics of a walking robot
NASA Astrophysics Data System (ADS)
Güémez, J.; Fiolhais, M.
2013-07-01
The physics of walking is explored, using a toy as a concrete example and a ‘toy model’ applied to it. Besides using Newton’s second law, the problem is also discussed from the thermodynamical perspective. Once the steady state (constant velocity) is achieved, we show that the internal energy of the toy is dissipated as heat in the surroundings.
Assessment of a Solar System Walk
ERIC Educational Resources Information Center
LoPresto, Michael C.; Murrell, Steven R.; Kirchner, Brian
2010-01-01
The idea of sending students and the general public on a walk through a scale model of the solar system in an attempt to instill an appreciation of the relative scales of the sizes of the objects compared to the immense distances between them is certainly not new. A good number of such models exist, including one on the National Mall in…
Moments of coinless quantum walks on lattices
NASA Astrophysics Data System (ADS)
Santos, Raqueline Azevedo Medeiros; Portugal, Renato; Boettcher, Stefan
2015-09-01
The properties of the coinless quantum-walk model have not been as thoroughly analyzed as those of the coined model. Both evolve in discrete time steps, but the former uses a smaller Hilbert space, which is spanned merely by the site basis. Besides, the evolution operator can be obtained using a process of lattice tessellation, which is very appealing. The moments of the probability distribution play an important role in the context of quantum walks. The ballistic behavior of the mean square displacement indicates that quantum-walk-based algorithms are faster than random-walk-based ones. In this paper, we obtain analytical expressions for the moments of the coinless model on d-dimensional lattices by employing the methods of Fourier transforms and generating functions. The mean square displacement for large times is explicitly calculated for the one- and two-dimensional lattices, and using optimization methods, the parameter values that give the largest spread are calculated and compared with the equivalent ones of the coined model. Although we have employed asymptotic methods, our approximations are accurate even for small numbers of time steps.
Coyote Walking Through Post-Wildfires
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...
Walking-Beam Solar-Cell Conveyor
NASA Technical Reports Server (NTRS)
Feder, H.; Frasch, W.
1982-01-01
Microprocessor-controlled walking-beam conveyor moves cells between work stations in automated assembly line. Conveyor has arm at each work station. In unison arms pick up all solar cells and advance them one station; then beam retracks to be in position for next step. Microprocessor sets beam stroke, speed, and position.
Go Naked: Diapers Affect Infant Walking
ERIC Educational Resources Information Center
Cole, Whitney G.; Lingeman, Jesse M.; Adolph, Karen E.
2012-01-01
In light of cross-cultural and experimental research highlighting effects of childrearing practices on infant motor skill, we asked whether wearing diapers, a seemingly innocuous childrearing practice, affects infant walking. Diapers introduce bulk between the legs, potentially exacerbating infants' poor balance and wide stance. We show that…
REINFORCED RANDOM WALKS AND ADIC TRANSFORMATIONS
Petersen, Karl
depending on the edges traversed. For example, in simple positive reinforcement each time that an edge, the simple oppositely reinforced system is the Euler adic [2,8,9], and the simple positively reinforcedREINFORCED RANDOM WALKS AND ADIC TRANSFORMATIONS SARAH BAILEY FRICK AND KARL PETERSEN Abstract
Elementary Education: Elementary Students Simulate Moon Walk.
ERIC Educational Resources Information Center
Aviation/Space, 1980
1980-01-01
Describes the project of a fourth- and fifth-grade class in simulating a moon walk. Teams consisted of the astronauts, the life support team, the flight program team, the communications team, the scientific team, and the construction team. Their visit to the Marshall Space Flight Center is also described. (SA)
Exploring Space and Place with Walking Interviews
ERIC Educational Resources Information Center
Jones, Phil; Bunce, Griff; Evans, James; Gibbs, Hannah; Hein, Jane Ricketts
2008-01-01
This article explores the use of walking interviews as a research method. In spite of a wave of interest in methods which take interviewing out of the "safe," stationary environment, there has been limited work critically examining the techniques for undertaking such work. Curiously for a method which takes an explicitly spatial approach, few…
The Physics of a Walking Robot
ERIC Educational Resources Information Center
Guemez, J.; Fiolhais, M.
2013-01-01
The physics of walking is explored, using a toy as a concrete example and a "toy model" applied to it. Besides using Newton's second law, the problem is also discussed from the thermodynamical perspective. Once the steady state (constant velocity) is achieved, we show that the internal energy of the toy is dissipated as heat in the…
Grover search with lackadaisical quantum walks
NASA Astrophysics Data System (ADS)
Wong, Thomas G.
2015-10-01
The lazy random walk, where the walker has some probability of staying put, is a useful tool in classical algorithms. We propose a quantum analogue, the lackadaisical quantum walk, where each vertex is given l self-loops, and we investigate its effects on Grover’s algorithm when formulated as search for a marked vertex on the complete graph of N vertices. For the discrete-time quantum walk using the phase flip coin, adding a self-loop to each vertex boosts the success probability from 1/2 to 1. Additional self-loops, however, decrease the success probability. Using instead the Shenvi, Kempe, and Whaley (2003) coin, adding self-loops simply slows down the search. These coins also differ in that the first is faster than classical when l scales less than N, while the second requires that l scale less than N 2. Finally, continuous-time quantum walks differ from both of these discrete-time examples—the self-loops make no difference at all. These behaviors generalize to multiple marked vertices.
Grover Search with Lackadaisical Quantum Walks
Thomas G. Wong
2015-09-24
The lazy random walk, where the walker has some probability of staying put, is a useful tool in classical algorithms. We propose a quantum analogue, the lackadaisical quantum walk, where each vertex is given $l$ self-loops, and we investigate its effects on Grover's algorithm when formulated as search for a marked vertex on the complete graph of $N$ vertices. For the discrete-time quantum walk using the phase flip coin, adding a self-loop to each vertex boosts the success probability from 1/2 to 1. Additional self-loops, however, decrease the success probability. Using instead the Ambainis, Kempe, and Rivosh (2005) coin, adding self-loops simply slows down the search. These coins also differ in that the first is faster than classical when $l$ scales less than $N$, while the second requires that $l$ scale less than $N^2$. Finally, continuous-time quantum walks differ from both of these discrete-time examples---the self-loops make no difference at all. These behaviors generalize to multiple marked vertices.
Random Walk Method for Potential Problems
NASA Technical Reports Server (NTRS)
Krishnamurthy, T.; Raju, I. S.
2002-01-01
A local Random Walk Method (RWM) for potential problems governed by Lapalace's and Paragon's equations is developed for two- and three-dimensional problems. The RWM is implemented and demonstrated in a multiprocessor parallel environment on a Beowulf cluster of computers. A speed gain of 16 is achieved as the number of processors is increased from 1 to 23.
Pellegrini, Barbara; Peyré-Tartaruga, Leonardo Alexandre; Zoppirolli, Chiara; Bortolan, Lorenzo; Bacchi, Elisabetta; Figard-Fabre, Hélène; Schena, Federico
2015-01-01
Nordic Walking (NW) owes much of its popularity to the benefits of greater energy expenditure and upper body engagement than found in conventional walking (W). Muscle activation during NW is still understudied, however. The aim of the present study was to assess differences in muscle activation and physiological responses between NW and W in level and uphill walking conditions. Nine expert Nordic Walkers (mean age 36.8±11.9 years; BMI 24.2±1.8 kg/m2) performed 5-minute treadmill trials of W and NW at 4 km/h on inclines of 0% and 15%. The electromyographic activity of seven upper body and five leg muscles and oxygen consumption (VO2) were recorded and pole force during NW was measured. VO2 during NW was 22.3% higher at 0% and only 6.9% higher at 15% than during W, while upper body muscle activation was 2- to 15-fold higher under both conditions. Lower body muscle activation was similarly increased during NW and W in the uphill condition, whereas the increase in erector spinae muscle activity was lower during NW than W. The lack of a significant increase in pole force during uphill walking may explain the lower extra energy expenditure of NW, indicating less upper body muscle activation to lift the body against gravity. NW seemed to reduce lower back muscle contraction in the uphill condition, suggesting that walking with poles may reduce effort to control trunk oscillations and could contribute to work production during NW. Although the difference in extra energy expenditure between NW and W was smaller in the uphill walking condition, the increased upper body muscle involvement during exercising with NW may confer additional benefit compared to conventional walking also on uphill terrains. Furthermore, people with low back pain may gain benefit from pole use when walking uphill. PMID:26418339
Walk Test Used to Monitor the Performance in the Health-Directed Nordic Walking
ERIC Educational Resources Information Center
Kamien, Dorota
2008-01-01
Study aim: To assess the performance of subjects engaged in health-directed Nordic Walking training (with poles) and subjected to 2-km walk test (no poles). Material and methods: A total of 72 subjects, including 8 men and 32 women aged 23-73 years and 32 female students aged 19-25 years participated in the study. They were subjected twice to 2-km…
Kleindienst, F I; Michel, K J; Schwarz, J; Krabbe, B
2006-03-01
Based on a higher cardio-pulmonary and cardio-vascular benefit and a promised reduction of mechanical load of the musculoskeletal system Nordic Walking (NW) shows an increased market potential. The present study should investigate whether there are biomechanical differences between the locomotion patterns NW, walking and running. Moreover possible resultant load differences should be determined. Eleven subjects, who were already experienced with the NW-technique, participated in this experiment. The kinematic data were collected using two high-speed camera systems from posterior and from lateral at the same time. Simultaneously the ground reaction forces were recorded. The kinematic and the kinetic data reveal differences between the three analyzed locomotion patterns. For NW as well as walking the mechanical load of the lower extremity is lower compared to running. None of the kinematic parameters suggest a "physiological benefit" of NW compared to walking. Moreover NW shows higher vertical and horizontal forces during landing. Exclusively the lower vertical force peak during push off indicates a lower mechanical load for NW in comparison to walking. Consequently it is questionable is NW -- based on its promised "biomechanical benefits" compared to walking -- should be still recommended for overweight people and for people with existing musculoskeletal problems of the lower limb. PMID:16544213
Universal quantum computation using the discrete-time quantum walk
Lovett, Neil B.; Cooper, Sally; Everitt, Matthew; Trevers, Matthew; Kendon, Viv
2010-04-15
A proof that continuous-time quantum walks are universal for quantum computation, using unweighted graphs of low degree, has recently been presented by A. M. Childs [Phys. Rev. Lett. 102, 180501 (2009)]. We present a version based instead on the discrete-time quantum walk. We show that the discrete-time quantum walk is able to implement the same universal gate set and thus both discrete and continuous-time quantum walks are computational primitives. Additionally, we give a set of components on which the discrete-time quantum walk provides perfect state transfer.
Scaling of the atmosphere of self-avoiding walks
A. L. Owczarek; T. Prellberg
2008-06-06
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.
One-dimensional lazy quantum walks and occupancy rate
NASA Astrophysics Data System (ADS)
Li, Dan; Michael, McGettrick; Zhang, Wei-Wei; Zhang, Ke-Jia
2015-05-01
In this paper, we discuss the properties of lazy quantum walks. Our analysis shows that the lazy quantum walks have O(tn) order of the n-th moment of the corresponding probability distribution, which is the same as that for normal quantum walks. The lazy quantum walk with a discrete Fourier transform (DFT) coin operator has a similar probability distribution concentrated interval to that of the normal Hadamard quantum walk. Most importantly, we introduce the concepts of occupancy number and occupancy rate to measure the extent to which the walk has a (relatively) high probability at every position in its range. We conclude that the lazy quantum walks have a higher occupancy rate than other walks such as normal quantum walks, classical walks, and lazy classical walks. Project supported by the National Natural Science Foundation of China (Grant Nos. 61272057 and 61170270), the Higher Education Young Elite Teacher Project of Beijing, China (Grant No. YETP0475 and YETP0477), the BUPT Excellent Ph. D. Students Foundation (Grant Nos. CX201325 and CX201326), and the China Scholarship Council (Grant No. 201306470046).
Cardiovascular Responses Associated with Daily Walking in Subacute Stroke
Prajapati, Sanjay K.; Gage, William H.; McIlroy, William E.
2013-01-01
Despite the importance of regaining independent ambulation after stroke, the amount of daily walking completed during in-patient rehabilitation is low. The purpose of this study is to determine if (1) walking-related heart rate responses reached the minimum intensity necessary for therapeutic aerobic exercise (40%–60% heart rate reserve) or (2) heart rate responses during bouts of walking revealed excessive workload that may limit walking (>80% heart rate reserve). Eight individuals with subacute stroke attending in-patient rehabilitation were recruited. Participants wore heart rate monitors and accelerometers during a typical rehabilitation day. Walking-related changes in heart rate and walking bout duration were determined. Patients did not meet the minimum cumulative requirements of walking intensity (>40% heart rate reserve) and duration (>10?minutes continuously) necessary for cardiorespiratory benefit. Only one patient exceeded 80% heart rate reserve. The absence of significant increases in heart rate associated with walking reveals that patients chose to walk at speeds well below a level that has meaningful cardiorespiratory health benefits. Additionally, cardiorespiratory workload is unlikely to limit participation in walking. Measurement of heart rate and walking during in-patient rehabilitation may be a useful approach to encourage patients to increase the overall physical activity and to help facilitate recovery. PMID:23476892
Random Walk Picture of Basketball Scoring
Gabel, Alan
2011-01-01
We present evidence, based on play-by-play data from all 6087 games from the 2006/07--2009/10 seasons of the National Basketball Association (NBA), that basketball scoring is well described by a weakly-biased continuous-time random walk. The time between successive scoring events follows an exponential distribution, with little memory between different scoring intervals. Using this random-walk picture that is augmented by features idiosyncratic to basketball, we account for a wide variety of statistical properties of scoring, such as the distribution of the score difference between opponents and the fraction of game time that one team is in the lead. By further including the heterogeneity of team strengths, we build a computational model that accounts for essentially all statistical features of game scoring data and season win/loss records of each team.
Discovering Walking Technicolor at LHC and Lattice
Koichi Yamawaki
2013-05-28
Walking technicolor, having a large anomalous dimension $\\gamma_m \\simeq 1$ and approximate scale symmetry, predicts Technidilaton, a light composite Higgs as a pseudo-Nambu-Goldstone boson of the approximate scale symmetry, which can be identified with the 125 GeV boson discovered at LHC. I will describe how such a {\\it weakly coupled light composite scalar} can be dynamically realized in the {\\it strongly coupled dynamics}, and can be fit to the current data at LHC, based on the ladder-like computation and the holographic one. I will also present results of our lattice collaboration (LatKMI Collaboration) searching for a walking theory and a light flavor-singlet scalar bound state in large $N_f$ QCD.
Holographic integral equations and walking technicolour
Raul Alvares; Nick Evans; Astrid Gebauer; George James Weatherill
2009-11-10
We study chiral symmetry breaking in the holographic D3-D7 system in a simple model with an arbitrary running coupling. We derive equations for the D7 embedding and show there is a light pion. In particular we present simple integral equations, involving just the running coupling and the quark self energy, for the quark condensate and the pion decay constant. We compare these to the Pagels-Stokar or constituent quark model equivalent. We discuss the implications for walking Technicolour theories. We also perform a similar analysis in the four dimensional field theory whose dual is the non-supersymmetric D3-D5 system and propose that it represents a walking theory in which the quark condensate has dimension 2 + sqrt{3}.
Holographic integral equations and walking technicolor
Alvares, Raul; Evans, Nick; Gebauer, Astrid; Weatherill, George James
2010-01-15
We study chiral symmetry breaking in the holographic D3-D7 system in a simple model with an arbitrary running coupling. We derive equations for the D7 embedding and show there is a light pion. In particular we present simple integral equations, involving just the running coupling and the quark self-energy, for the quark condensate and the pion decay constant. We compare these to the Pagels-Stokar or constituent quark model equivalent. We discuss the implications for walking technicolor theories. We also perform a similar analysis in the four-dimensional field theory whose dual is the nonsupersymmetric D3-D5 system and propose that it represents a walking theory in which the quark condensate has dimension 2+{radical}(3)
Generalized ruin problems and asynchronous random walks
NASA Astrophysics Data System (ADS)
Abad, E.
2005-07-01
We consider a gambling game with two different kinds of trials and compute the duration of the game (averaged over all possible initial capitals of the players) by a mapping of the problem to a 1D lattice walk of two particles reacting upon encounter. The relative frequency of the trials is governed by the synchronicity parameter p of the random walk. The duration of the game is given by the mean time to reaction, which turns out to display a different behavior for even and odd lattices, i.e. this quantity is monotonic in p for odd lattices and non-monotonic for even lattices. In the game picture, this implies that the players minimize the duration of the game by restricting themselves to one type of trial if their joint capital is odd, otherwise a non-symmetric mixture of both trials is needed.
An invariance property of diffusive random walks
NASA Astrophysics Data System (ADS)
Blanco, S.; Fournier, R.
2003-01-01
Starting from a simple animal-biology example, a general, somewhat counter-intuitive property of diffusion random walks is presented. It is shown that for any (non-homogeneous) purely diffusing system, under any isotropic uniform incidence, the average length of trajectories through the system (the average length of the random walk trajectories from entry point to first exit point) is independent of the characteristics of the diffusion process and therefore depends only on the geometry of the system. This exact invariance property may be seen as a generalization to diffusion of the well-known mean-chord-length property (Case K. M. and Zweifel P. F., Linear Transport Theory (Addison-Wesley) 1967), leading to broad physics and biology applications.
Random walks on finite lattices with traps
NASA Astrophysics Data System (ADS)
Hatlee, Michael D.; Kozak, John J.
1980-02-01
We consider dissipative processes involving both chemical reaction and physical diffusion in systems for which the influence of boundaries and system size on the dynamics cannot be neglected. We report the results of Monte Carlo simulations on an irreversible reaction in a confined system subject to two sorts of finite boundary conditions. The problem is posed in such a way as to take maximal advantage of two earlier studies: Montroll's work on random walks on d-dimensional periodic lattices with traps, and the work of Sanders, Ruijgrok, and ten Bosch on random walks on two-dimensional finite lattices with traps. Our results are used to discuss the concept of reduction of dimensionality as introduced by Adam and Delbrück in their study of biological diffusion processes.
Quantum Walks and discrete Gauge Theories
Pablo Arnault; Fabrice Debbasch
2015-10-30
A particular example is produced to prove that quantum walks can be used to simulate full-fledged discrete gauge theories. A new family of $(1 + 2)$-dimensional walks is introduced and its continuous limit is shown to coincide with the dynamics of a Dirac fermion coupled to arbitrary electromagnetic fields. The electromagnetic interpretation is extended beyond the continuous limit by proving that these DTQWs exhibit an exact discrete local $U(1)$ gauge invariance and possess a discrete gauge-invariant conserved current. A discrete gauge-invariant electromagnetic field is also constructed and that field is coupled to the conserved current by a discrete generalization of Maxwell equations. The dynamics of the DTQWs under crossed electric and magnetic fields is finally explored outside the continuous limit by numerical simulations. Bloch oscillations and the so-called ${\\bf E} \\times {\\bf B}$ drift are recovered in the weak-field limit. Localization is observed for some values of the gauge fields.
Quantum walks in the density operator picture
Chaobin Liu
2015-06-08
A new approach to quantum walks is presented. Considering a quantum system undergoing some unitary discrete-time evolution in a directed graph G, we think of the vertices of G as sites that are occupied by the quantum system, whose internal state is described by density operators. To formulate the unitary evolution, we define reflections in the tensor product of an internal Hilbert space and a spatial Hilbert space. We then construct unitary channels that govern the evolution of the system in the graph. The discrete dynamics of the system (called quantum walks) is obtained by iterating the unitary channel on the density operator of the quantum system. It turns out that in this framework, the action of the unitary channel on a density operator is described by the usual matrix multiplication.
Early independent walking: a longitudinal study of load perturbation effects.
Vereijken, Beatrix; Pedersen, Arve Vorland; Størksen, Jan Harry
2009-05-01
This study investigated infants' ability to adapt to experimentally induced changes in their body dimensions at walk onset, and how this ability is affected by increased walking experience. Fifteen infants were studied over their first 6 months of independent walking with a load perturbation design. They traversed a walkway with loads symmetrically placed around the shoulders, waist, or ankles, and without loading. At walk onset, infants fell more with shoulder and ankle loads than with waist or no loads. Shoulder loads further resulted in higher walking speed and longer steps, while waist loads resulted in increased walking speed and larger foot rotation. Ankle loads disrupted walking proficiency the most, as indicated by lower walking speed, shorter steps, larger foot rotation, and smaller step-to-step angle. Step width was not differentially affected by the conditions. With increased experience, walking proficiency increased across all conditions, but ankle loads lagged behind the other conditions. Loading effects are discussed with respect to walking experience and position of the loads on the body. PMID:19365798
A Random Walk Picture of Basketball
NASA Astrophysics Data System (ADS)
Gabel, Alan; Redner, Sidney
2012-02-01
We analyze NBA basketball play-by-play data and found that scoring is well described by a weakly-biased, anti-persistent, continuous-time random walk. The time between successive scoring events follows an exponential distribution, with little memory between events. We account for a wide variety of statistical properties of scoring, such as the distribution of the score difference between opponents and the fraction of game time that one team is in the lead.
Green function approach for scattering quantum walks
F. M. Andrade; M. G. E. da Luz
2011-12-12
In this work a Green function approach for scattering quantum walks is developed. The exact formula has the form of a sum over paths and always can be cast into a closed analytic expression for arbitrary topologies and position dependent quantum amplitudes. By introducing the step and path operators, it is shown how to extract any information about the system from the Green function. The method relevant features are demonstrated by discussing in details an example, a general diamond-shaped graph.
Green function approach for scattering quantum walks
Andrade, F M; 10.1103/PhysRevA.84.042343
2011-01-01
In this work a Green function approach for scattering quantum walks is developed. The exact formula has the form of a sum over paths and always can be cast into a closed analytic expression for arbitrary topologies and position dependent quantum amplitudes. By introducing the step and path operators, it is shown how to extract any information about the system from the Green function. The method relevant features are demonstrated by discussing in details an example, a general diamond-shaped graph.
Walking vector soliton caging and releasing
Kartashov, Yaroslav V; Torner, Lluis
2009-01-01
We address the formation and propagation of vector solitons in optical lattices in the presence of anisotropy-induced walk-off between ordinary and extraordinary polarized field components. Stable vector solitons trapped by the lattice form above a threshold power, while decreasing the lattice depth below a critical value results in the abrupt release of the caged solitons, that then move across the lattice and may get trapped in a desired lattice channel.
Junji Jia; Shinya Matsuzaki; Koichi Yamawaki
2013-01-10
We calculate techni-pion masses of the walking technicolor (WTC), by explicitly evaluating nontrivial contributions from various possible chiral breaking sources in a concrete WTC setting of the one-family model. Our explicit computation of the mass and the coupling in this concrete model setting reveals that the techni-pions are on the order of several hundred GeV in the region to be discovered at LHC.
Mesonic spectroscopy of Minimal Walking Technicolor
Luigi Del Debbio; Biagio Lucini; Agostino Patella; Claudio Pica; Antonio Rago
2010-04-19
We investigate the structure and the novel emerging features of the mesonic non-singlet spectrum of the Minimal Walking Technicolor (MWT) theory. Precision measurements in the nonsinglet pseudoscalar and vector channels are compared to the expectations for an IR-conformal field theory and a QCD-like theory. Our results favor a scenario in which MWT is (almost) conformal in the infrared, while spontaneous chiral symmetry breaking seems less plausible.
Weak limits for quantum random walks
NASA Astrophysics Data System (ADS)
Grimmett, Geoffrey; Janson, Svante; Scudo, Petra F.
2004-02-01
We formulate and prove a general weak limit theorem for quantum random walks in one and more dimensions. With Xn denoting position at time n, we show that Xn/n converges weakly as n?? to a certain distribution which is absolutely continuous and of bounded support. The proof is rigorous and makes use of Fourier transform methods. This approach simplifies and extends certain preceding derivations valid in one dimension that make use of combinatorial and path integral methods.
Fractal landscape analysis of DNA walks
NASA Technical Reports Server (NTRS)
Peng, C. K.; Buldyrev, S. V.; Goldberger, A. L.; Havlin, S.; Sciortino, F.; Simons, M.; Stanley, H. E.
1992-01-01
By mapping nucleotide sequences onto a "DNA walk", we uncovered remarkably long-range power law correlations [Nature 356 (1992) 168] that imply a new scale invariant property of DNA. We found such long-range correlations in intron-containing genes and in non-transcribed regulatory DNA sequences, but not in cDNA sequences or intron-less genes. In this paper, we present more explicit evidences to support our findings.
Integrated system for single leg walking
NASA Astrophysics Data System (ADS)
Simmons, Reid; Krotkov, Eric; Roston, Gerry
1990-07-01
The Carnegie Mellon University Planetary Rover project is developing a six-legged walking robot capable of autonomously navigating, exploring, and acquiring samples in rugged, unknown environments. This report describes an integrated software system capable of navigating a single leg of the robot over rugged terrain. The leg, based on an early design of the Ambler Planetary Rover, is suspended below a carriage that slides along rails. To walk, the system creates an elevation map of the terrain from laser scanner images, plans an appropriate foothold based on terrain and geometric constraints, weaves the leg through the terrain to position it above the foothold, contacts the terrain with the foot, and applies force enough to advance the carriage along the rails. Walking both forward and backward, the system has traversed hundreds of meters of rugged terrain including obstacles too tall to step over, trenches too deep to step in, closely spaced obstacles, and sand hills. The implemented system consists of a number of task-specific processes (two for planning, two for perception, one for real-time control) and a central control process that directs the flow of communication between processes.
Modulation of Head Movement Control During Walking
NASA Technical Reports Server (NTRS)
Mulavara, Ajitkumar P.; Verstraete, Mary C.; Bloomberg, Jacob J.; Paloski, William H. (Technical Monitor)
1999-01-01
The purpose of this study was to investigate the coordination of the head relative to the trunk within a gait cycle during gaze fixation. Nine normal subjects walked on a motorized treadmill driven at 1.79 m/sec (20 s trials) while fixing their gaze on a centrally located earth-fixed target positioned at a distance of 2m from their eyes. The relative motion of the head and the net torque acting on it relative to the trunk during the gait cycle were used as measures of coordination. It was found that the net torque applied to the head counteracts the destabilizing forces acting on the upper body during locomotion. The average net torque impulse was significantly different (p less than 0.05) between the heel strike and swing phases and were found to be symmetrical between the right and left leg events of the gait cycle. However, the average net displacement of the head relative to the trunk was maintained uniform (p greater than 0.05) throughout the gait cycle. Thus, the coordination of the motion of the head relative to the trunk during walking is dynamically modulated depending on the behavioral events occurring in the gait cycle. This modulation may serve to aid stabilization of the head by counteracting the force variations acting on the upper body that may aid in the visual fixing of targets during walking.
Visual Evoked Responses During Standing and Walking
Gramann, Klaus; Gwin, Joseph T.; Bigdely-Shamlo, Nima; Ferris, Daniel P.; Makeig, Scott
2010-01-01
Human cognition has been shaped both by our body structure and by its complex interactions with its environment. Our cognition is thus inextricably linked to our own and others’ motor behavior. To model brain activity associated with natural cognition, we propose recording the concurrent brain dynamics and body movements of human subjects performing normal actions. Here we tested the feasibility of such a mobile brain/body (MoBI) imaging approach by recording high-density electroencephalographic (EEG) activity and body movements of subjects standing or walking on a treadmill while performing a visual oddball response task. Independent component analysis of the EEG data revealed visual event-related potentials that during standing, slow walking, and fast walking did not differ across movement conditions, demonstrating the viability of recording brain activity accompanying cognitive processes during whole body movement. Non-invasive and relatively low-cost MoBI studies of normal, motivated actions might improve understanding of interactions between brain and body dynamics leading to more complete biological models of cognition. PMID:21267424
From Lévy walks to superdiffusive shock acceleration
Zimbardo, Gaetano; Perri, Silvia E-mail: silvia.perri@fis.unical.it
2013-11-20
In this paper, we present a general scenario for nondiffusive transport and we investigate the influence of anomalous, superdiffusive transport on Fermi acceleration processes at shocks. We explain why energetic particle superdiffusion can be described within the Lévy walk framework, which is based on a power-law distribution of free path lengths and on a coupling between free path length and free path duration. A self-contained derivation of the particle mean square displacement, which grows as (?x {sup 2}) = 2D {sub ?} t {sup ?} with ? > 1, and the particle propagator, is presented for Lévy walks, making use of a generalized version of the Montroll-Weiss equation. We also derive for the first time an explicit expression for the anomalous diffusion coefficient D {sub ?} and we discuss how to obtain these quantities from energetic particle observations in space. The results are applied to the case of particle acceleration at an infinite planar shock front. Using the scaling properties of the Lévy walk propagator, the energy spectral indices are found to have values smaller than the ones predicted by the diffusive shock acceleration theory. Furthermore, when applying the results to ions with energies of a few MeV accelerated at the solar wind termination shock, the estimation of the anomalous diffusion coefficient associated with the superdiffusive motion gives acceleration times much smaller than the ones related to normal diffusion.
Marselle, Melissa R.; Irvine, Katherine N.; Warber, Sara L.
2013-01-01
The benefits of walking in natural environments for well-being are increasingly understood. However, less well known are the impacts different types of natural environments have on psychological and emotional well-being. This cross-sectional study investigated whether group walks in specific types of natural environments were associated with greater psychological and emotional well-being compared to group walks in urban environments. Individuals who frequently attended a walking group once a week or more (n = 708) were surveyed on mental well-being (Warwick Edinburgh Mental Well-being Scale), depression (Major Depressive Inventory), perceived stress (Perceived Stress Scale) and emotional well-being (Positive and Negative Affect Schedule). Compared to group walks in urban environments, group walks in farmland were significantly associated with less perceived stress and negative affect, and greater mental well-being. Group walks in green corridors were significantly associated with less perceived stress and negative affect. There were no significant differences between the effect of any environment types on depression or positive affect. Outdoor walking group programs could be endorsed through “green prescriptions” to improve psychological and emotional well-being, as well as physical activity. PMID:24173142
Takeshima, Nobuo; Islam, Mohammod M.; Rogers, Michael E.; Rogers, Nicole L.; Sengoku, Naoko; Koizumi, Daisuke; Kitabayashi, Yukiko; Imai, Aiko; Naruse, Aiko
2013-01-01
The purpose of this study was to compare the effects of Nordic walking with conventional walking and band-based resistance exercise on functional fitness, static balance and dynamic balance in older adults. Volunteers (n = 65) were divided into four groups: Nordic walking (NW), conventional walking (CW), resistance (RES), and control. Each group performed activity 50-70 min·day?1 (warm-up 10-15 min, main exercise 30-40, and cool down 10-15 min), 3 days·week?1 (NW and CW) or 2 day·week?1 (RES) for 12 wks. Upper-body strength improved (p < 0. 05) in the RES (22.3%) and the NW (11.6%) groups compared to the CW and control groups. Cardio- respiratory fitness improved more in the NW (10.9%) and CW (10.6%) groups compared to the RES and control groups. Upper- and lower-body flexibility also improved in all exercise groups compared to the control group. There were no improvements in balance measures in any group. While all modes of exercise improved various components of fitness, Nordic walking provided the best well-rounded benefits by improving upper-body strength, cardiovascular endurance, and flexibility. Therefore, Nordic walking is recommended as an effective and efficient mode of concurrent exercise to improve overall functional fitness in older adults. Key Points Nordic walking, conventional walking, and resistance training are beneficial for older adults. Nordic walking and conventional walking both improve cardio-respiratory fitness while resistance training does not. Nordic walking provides additional benefits in upper-body muscular strength compared to conventional walking. Nordic walking is an effective and efficient mode of exercise to improve overall fitness in older adults. PMID:24149147
Using a controller based on reinforcement learning for a passive dynamic walking robot
van Vliet, Lucas J.
1 Using a controller based on reinforcement learning for a passive dynamic walking robot E of the difficulties with passive dynamic walking is the stability of walking. In our robot, small uneven or tilted prototype of passive dynamic walking robot with a conventional feedback controller. The successful walking
Building/dept. name & number Address Alexander Theatre (7) 48 Exhibition Walk
Li, Yuan-Fang
Building/dept. name & number Address Alexander Theatre (7) 48 Exhibition Walk Australian Pulp Chancellery Building A (3A) 27 Chancellors Walk Chancellery Building B (3B) 36 Exhibition Walk Chancellery Building C (3C) 34 Exhibition Walk Chancellery Building D (3D) 26 Sports Walk Chancellery Building E (3E
Bushman, Frederic
Walking West on spruce street, turn left on to the 36th Street pathway. At the end of this pathway is Hamil-1. ton Walk. Turn right on Hamilton Walk. Enter Johnson Pavilion (red circle on map) and ask the guard to let you in to the doors to the John Morgan2. Building (doors on right). Walk down the hall
Depressive Symptoms, Social Support, and Walking Among Hispanic Older Adults
Perrino, Tatiana; Brown, Scott C.; Huang, Shi; Brown, C. Hendricks; Gómez, Gianna Pérez; Pantin, Hilda; Szapocznik, José
2013-01-01
Objectives Depressive symptoms and physical inactivity are health risks among minority older adults. This study examined whether social support moderated the relationship of depressive symptoms to walking behavior among 217 community-dwelling, Hispanic older adults. Method Cross-sectional analyses were used to test whether different forms of social support interacted with depressive symptoms to affect both likelihood and amount of walking. Results Analyses showed a significant interaction between depressive symptoms and instrumental support related to the likelihood of walking and a marginally significant interaction between depressive symptoms and instrumental social support related to the amount of walking. Depressive symptoms were associated with a lower likelihood and lower amount of walking among participants receiving high levels of instrumental social support (e.g., help with chores) but not low instrumental support. Emotional and informational support did not moderate the depression to walking relationship. Conclusion Receiving too much instrumental support was related to sedentary behavior among depressed older adults. PMID:21508305
Walks4work: Rationale and study design to investigate walking at lunchtime in the workplace setting
2012-01-01
Background Following recruitment of a private sector company, an 8?week lunchtime walking intervention was implemented to examine the effect of the intervention on modifiable cardiovascular disease risk factors, and further to see if walking environment had any further effect on the cardiovascular disease risk factors. Methods For phase 1 of the study participants were divided into three groups, two lunchtime walking intervention groups to walk around either an urban or natural environment twice a week during their lunch break over an 8?week period. The third group was a waiting-list control who would be invited to join the walking groups after phase 1. In phase 2 all participants were encouraged to walk during their lunch break on self-selecting routes. Health checks were completed at baseline, end of phase 1 and end of phase 2 in order to measure the impact of the intervention on cardiovascular disease risk. The primary outcome variables of heart rate and heart rate variability were measured to assess autonomic function associated with cardiovascular disease. Secondary outcome variables (Body mass index, blood pressure, fitness, autonomic response to a stressor) related to cardiovascular disease were also measured. The efficacy of the intervention in increasing physical activity was objectively monitored throughout the 8-weeks using an accelerometer device. Discussion The results of this study will help in developing interventions with low researcher input with high participant output that may be implemented in the workplace. If effective, this study will highlight the contribution that natural environments can make in the reduction of modifiable cardiovascular disease risk factors within the workplace. PMID:22830646
Optimal speeds for walking and running, and walking on a moving walkway
NASA Astrophysics Data System (ADS)
Srinivasan, Manoj
2009-06-01
Many aspects of steady human locomotion are thought to be constrained by a tendency to minimize the expenditure of metabolic cost. This paper has three parts related to the theme of energetic optimality: (1) a brief review of energetic optimality in legged locomotion, (2) an examination of the notion of optimal locomotion speed, and (3) an analysis of walking on moving walkways, such as those found in some airports. First, I describe two possible connotations of the term "optimal locomotion speed:" that which minimizes the total metabolic cost per unit distance and that which minimizes the net cost per unit distance (total minus resting cost). Minimizing the total cost per distance gives the maximum range speed and is a much better predictor of the speeds at which people and horses prefer to walk naturally. Minimizing the net cost per distance is equivalent to minimizing the total daily energy intake given an idealized modern lifestyle that requires one to walk a given distance every day—but it is not a good predictor of animals' walking speeds. Next, I critique the notion that there is no energy-optimal speed for running, making use of some recent experiments and a review of past literature. Finally, I consider the problem of predicting the speeds at which people walk on moving walkways—such as those found in some airports. I present two substantially different theories to make predictions. The first theory, minimizing total energy per distance, predicts that for a range of low walkway speeds, the optimal absolute speed of travel will be greater—but the speed relative to the walkway smaller—than the optimal walking speed on stationary ground. At higher walkway speeds, this theory predicts that the person will stand still. The second theory is based on the assumption that the human optimally reconciles the sensory conflict between the forward speed that the eye sees and the walking speed that the legs feel and tries to equate the best estimate of the forward speed to the naturally preferred speed. This sensory conflict theory also predicts that people would walk slower than usual relative to the walkway yet move faster than usual relative to the ground. These predictions agree qualitatively with available experimental observations, but there are quantitative differences.
The bottom-supported walking drilling rig Shengli-2
Gu Xinyi; Bin Ruji; Ma Zhiliang; Chen Jianyuan
1993-12-31
A new type of offshore rig--the bottom supported walking drilling rig was developed in China and has been completed successfully. It is rig Shengli-2. Rig Shengli-2 consists of an inner body and outer body. In condition of mutual support they can be seated down and lifted up alternatively and can also be moved forward (or backward) by means of the hydraulic walking mechanism which makes the walking possible.
Exact solutions for restricted walks with applications to polymers
NASA Astrophysics Data System (ADS)
Batchelor, M. T.; Henry, B. I.
1991-02-01
The combinatorial theory of runs is used to algebraically enumerate new classes of restricted random walks and restricted self-avoiding walks. The restrictions favour the local formation of either cis or trans configurations. Exact results are derived and presented for the connective constant and corresponding exponent value for walks on d-dimensional hypercubic lattices. Preliminary numerical results for the mean square end-to-end distance exponent are also given.
Discrete-time Quantum Walks in random artificial Gauge Fields
G. Di Molfetta; F. Debbasch
2015-05-30
Discrete-time quantum walks (DTQWs) in random artificial electric and gravitational fields are studied analytically and numerically. The analytical computations are carried by a new method which allows a direct exact analytical determination of the equations of motion obeyed by the average density operator. It is proven that randomness induces decoherence and that the quantum walks behave asymptotically like classical random walks. Asymptotic diffusion coefficients are computed exactly. The continuous limit is also obtained and discussed.
Mall Walking Program Environments, Features, and Participants: A Scoping Review
Belza, Basia; Allen, Peg; Brolliar, Sarah; Brown, David R.; Cormier, Marc L.; Janicek, Sarah; Jones, Dina L.; King, Diane K.; Marquez, David X.; Rosenberg, Dori E.
2015-01-01
Introduction Walking is a preferred and recommended physical activity for middle-aged and older adults, but many barriers exist, including concerns about safety (ie, personal security), falling, and inclement weather. Mall walking programs may overcome these barriers. The purpose of this study was to summarize the evidence on the health-related value of mall walking and mall walking programs. Methods We conducted a scoping review of the literature to determine the features, environments, and benefits of mall walking programs using the RE-AIM framework (reach, effectiveness, adoption, implementation, and maintenance). The inclusion criteria were articles that involved adults aged 45 years or older who walked in indoor or outdoor shopping malls. Exclusion criteria were articles that used malls as laboratory settings or focused on the mechanics of walking. We included published research studies, dissertations, theses, conference abstracts, syntheses, nonresearch articles, theoretical papers, editorials, reports, policy briefs, standards and guidelines, and nonresearch conference abstracts and proposals. Websites and articles written in a language other than English were excluded. Results We located 254 articles on mall walking; 32 articles met our inclusion criteria. We found that malls provided safe, accessible, and affordable exercise environments for middle-aged and older adults. Programmatic features such as program leaders, blood pressure checks, and warm-up exercises facilitated participation. Individual benefits of mall walking programs included improvements in physical, social, and emotional well-being. Limited transportation to the mall was a barrier to participation. Conclusion We found the potential for mall walking programs to be implemented in various communities as a health promotion measure. However, the research on mall walking programs is limited and has weak study designs. More rigorous research is needed to define best practices for mall walking programs’ reach, effectiveness, adoption, implementation, and maintenance. PMID:26270743
Tempo and walking speed with music in the urban context
Fran?k, Marek; van Noorden, Leon; Režný, Lukáš
2014-01-01
The study explored the effect of music on the temporal aspects of walking behavior in a real outdoor urban setting. First, spontaneous synchronization between the beat of the music and step tempo was explored. The effect of motivational and non-motivational music (Karageorghis et al., 1999) on the walking speed was also studied. Finally, we investigated whether music can mask the effects of visual aspects of the walking route environment, which involve fluctuation of walking speed as a response to particular environmental settings. In two experiments, we asked participants to walk around an urban route that was 1.8 km in length through various environments in the downtown area of Hradec Králové. In Experiment 1, the participants listened to a musical track consisting of world pop music with a clear beat. In Experiment 2, participants were walking either with motivational music, which had a fast tempo and a strong rhythm, or with non-motivational music, which was slower, nice music, but with no strong implication to movement. Musical beat, as well as the sonic character of the music listened to while walking, influenced walking speed but did not lead to precise synchronization. It was found that many subjects did not spontaneously synchronize with the beat of the music at all, and some subjects synchronized only part of the time. The fast, energetic music increases the speed of the walking tempo, while slower, relaxing music makes the walking tempo slower. Further, it was found that listening to music with headphones while walking can mask the influence of the surrounding environment to some extent. Both motivational music and non-motivational music had a larger effect than the world pop music from Experiment 1. Individual differences in responses to the music listened to while walking that were linked to extraversion and neuroticism were also observed. The findings described here could be useful in rhythmic stimulation for enhancing or recovering the features of movement performance. PMID:25520682
18.366 Random Walks and Diffusion, Spring 2003
Bazant, Martin Z.
Discrete and continuum modeling of diffusion processes in physics, chemistry, and economics. Topics include central limit theorems, continuous-time random walks, Levy flights, correlations, extreme events, mixing, ...
Mechanism And Control Of The Quadruped Walking Robot
NASA Astrophysics Data System (ADS)
Adachi, Hironori; Nakano, Eiji; Koyachi, Noriho
1987-10-01
This paper provides a description of the quadruped walking robot "TURTLE-1". A new link mechanism named ASTBALLEM is used for the legs of this robot. With this mechanism highly rigid and easily controllable legs are constructed. Each leg has two degrees of freedom and is driven by two DC servo motors. The motion of the legs is controlled by a micro computer and various gaits are generated. Static stability is maintained as the robot walks. Moreover, its walk is quasi-dynamic; that is, it has a manner of walking that has a two legged supporting period.
18.366 Random Walks and Diffusion, Spring 2005
Bazant, Martin Z.
Discrete and continuum modeling of diffusion processes in physics, chemistry, and economics. Topics include central limit theorems, continuous-time random walks, Levy flights, correlations, extreme events, mixing, ...
Walking control of small size humanoid robot: HAJIME ROBOT 18
NASA Astrophysics Data System (ADS)
Sakamoto, Hajime; Nakatsu, Ryohei
2007-12-01
HAJIME ROBOT 18 is a fully autonomous biped robot. It has been developed for RoboCup which is a worldwide soccer competition of robots. It is necessary for a robot to have high mobility to play soccer. High speed walking and all directional walking are important to approach and to locate in front of a ball. HAJIME ROBOT achieved these walking. This paper describes walking control of a small size humanoid robot 'HAJIME ROBOT 18' and shows the measurement result of ZMP (Zero Moment Point). HAJIME ROBOT won the Robotics Society of Japan Award in RoboCup 2005 and in RoboCup 2006 Japan Open.
Metal-insulator transition in 2D quantum walks
NASA Astrophysics Data System (ADS)
Edge, Jonathan; Asboth, Janos
2015-03-01
We investigate the localisation properties due to disorder of several different two-dimensional quantum walks. We find that, contrary to claims in the literature, the Hadamard quantum walk does not localise. In a different quantum walk system we find a way to induce localisation. By tuning the parameters of the system we further manage to drive the quantum walk through a metal-insulator transition and show that the transition is related to the plateau transition of the integer quantum Hall effect. Hungarian National Office for Research.
Qubit state transfer via discrete-time quantum walks
NASA Astrophysics Data System (ADS)
Yalç?nkaya, ?skender; Gedik, Zafer
2015-06-01
We propose a scheme for perfect transfer of an unknown qubit state via the discrete-time quantum walk on a line or a circle. For this purpose, we introduce an additional coin operator which is applied at the end of the walk. This operator does not depend on the state to be transferred. We show that perfect state transfer over an arbitrary distance can be achieved only if the walk is driven by an identity or a flip coin operator. Other biased coin operators and the Hadamard coin allow perfect state transfer over finite distances only. Furthermore, we show that quantum walks ending with a perfect state transfer are periodic.
Assessing walking speed in clinical research: a systematic review
Graham, James E.; Ostir, Glenn V.; Fisher, Steven R.; Ottenbacher, Kenneth J.
2009-01-01
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
Prediction of walking speed using single stance force or pressure measurements in healthy subjects.
Keijsers, N L W; Stolwijk, N M; Renzenbrink, G J; Duysens, J
2016-01-01
Walking speed is one of the best measures of overall walking capacity. In plantar pressure measurements, walking speed can be assessed using contact time, but it is only moderately correlated with walking speed. The center of pressure might be of more value to indicate walking speed since walking speed alters foot loading. Therefore, the purpose of this study is to assess walking speed using the velocity of the center of pressure (VCOP). Thirty-three subjects walked over a Footscan pressure plate at three speed conditions; slow, preferred, and fast. Walking speed was measured by a motion analysis system. (Multiple) linear regression analysis was used to indicate the relation between walking speed and independent variables derived from the pressure plate such as mean VCOP and stance time for all walking conditions separately and together. The mean VCOP had the highest correlation coefficient value with walking speed for all walking conditions combined (0.94) and for the preferred walking condition (0.80). The multiple regression analysis, based on a number of additional parameters, revealed a small to modest increase in the performance of predicting walking speed (r=0.98 for combined and r=0.93 for preferred). The mean VCOP was the best predictor for walking speed when using a plantar pressure plate. The mean VCOP predicts the walking speed with a 95% accuracy of 0.20m/s when healthy subjects walk at their preferred walking speed. PMID:26669958
76 FR 21579 - Energy Conservation Program: Test Procedures for Walk-In Coolers and Walk-In Freezers
Federal Register 2010, 2011, 2012, 2013, 2014
2011-04-15
...On January 4, 2010, the U.S. Department of Energy (DOE) issued a notice of proposed rulemaking (January 2010 NOPR) to establish new test procedures for walk-in coolers and walk-in freezers (WICF or walk- ins). On September 9, 2010, DOE issued a supplemental notice of proposed rulemaking (September 2010 SNOPR) to propose changes to the test procedures that it proposed in the NOPR. Those......
Licence, Sammy; Smith, Robynne; McGuigan, Miranda P.; Earnest, Conrad P.
2015-01-01
Objectives Mobile phone texting is a common daily occurrence with a paucity of research examining corresponding gait characteristics. To date, most studies have participants walk in a straight line vs. overcoming barriers and obstacles that occur during regular walking. The aim of our study is to examine the effect of mobile phone texting during periods of cognitive distraction while walking and negotiating barriers synonymous with pedestrian traffic. Methods Thirty participants (18-50y) completed three randomized, counter-balanced walking tasks over a course during: (1) normal walking (control), (2) texting and walking, and (3) texting and walking whilst being cognitively distraction via a standard mathematical test performed while negotiating the obstacle course. We analyzed gait characteristics during course negotiation using a 3-dimensional motion analysis system and a general linear model and Dunnet-Hsu post-hoc procedure the normal walking condition to assess gait characteristic differences. Primary outcomes included the overall time to complete the course time and barrier contact. Secondary outcomes included obstacle clearance height, step frequency, step time, double support phase and lateral deviation. Results Participants took significantly longer (mean ± SD) to complete the course while texting (24.96±4.20 sec) and during cognitive distraction COG (24.09±3.36 sec) vs. normal walking (19.32±2.28 sec; all, P<0.001). No significant differences were noted for barrier contacts (P = 0.28). Step frequency, step time, double support phase and lateral deviation all increased in duration during the texting and cognitive distraction trial. Texting and being cognitively distracted also increased obstacle clearance versus the walking condition (all, P<0.02). Conclusions Texting while walking and/or being cognitively distracted significantly affect gait characteristics concordant to mobile phone usage resulting in a more cautious gate pattern. Future research should also examine a similar study in older participants who may be at a greater risk of tripping with such walking deviations. PMID:26222430
ERIC Educational Resources Information Center
Lancioni, Giulio E.; Singh, Nirbhay N.; O'Reilly, Mark F.; Sigafoos, Jeff; La Martire, Maria L.; Oliva, Doretta; Groeneweg, Jop
2012-01-01
These two case studies assessed technology-based programs for promoting walking fluency and improving foot-ground contact during walking with a man and a woman with multiple disabilities, respectively. The man showed breaks during walking and the woman presented with toe walking. The technology used in the studies included a microprocessor with…
Code of Federal Regulations, 2010 CFR
2010-01-01
... consumption of walk-in coolers and walk-in freezers. 431.304 Section 431.304 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION ENERGY EFFICIENCY PROGRAM FOR CERTAIN COMMERCIAL AND INDUSTRIAL EQUIPMENT Walk-in Coolers and Walk-in Freezers Test Procedures § 431.304 Uniform test method for the measurement of...
Redner, Sidney
Chapter 2 RANDOM WALK/DIFFUSION Because the random walk and its continuum di#usion limit underlie to this central topic. There are several complementary ways to describe random walks and di#usion, each that represents a minimalist description for the stochastic motion of a random walk. We mostly restrict ourselves
Federal Register 2010, 2011, 2012, 2013, 2014
2013-05-01
...Comment Request; Walking-Working Surfaces Standard ACTION...ICR) titled, ``Walking-Working Surfaces Standard,'' to...requirements in the Walking-Working Surfaces Standard protect workers...authorized agent, in a conspicuous place in each space to which...
Federal Register 2010, 2011, 2012, 2013, 2014
2012-10-23
...Safety Zone: Leukemia & Lymphoma Light the Night Walk Fireworks Display; Willamette...during the Leukemia & Lymphoma Light the Night Walk fireworks display from 6...Safety Zone; Leukemia & Lymphoma Light the Night Walk Fireworks Display;...
10 CFR 429.53 - Walk-in coolers and walk-in freezers.
Code of Federal Regulations, 2014 CFR
2014-01-01
10 Energy 3 2014-01-01 2014-01-01 false Walk-in...addition, for those WICFs with transparent reach-in doors and windows: The glass type of the doors and windows (e.g., double-pane with heat reflective...
10 CFR 429.53 - Walk-in coolers and walk-in freezers.
Code of Federal Regulations, 2012 CFR
2012-01-01
10 Energy 3 2012-01-01 2012-01-01 false Walk-in...addition, for those WICFs with transparent reach-in doors and windows: The glass type of the doors and windows (e.g., double-pane with heat reflective...
10 CFR 429.53 - Walk-in coolers and walk-in freezers.
Code of Federal Regulations, 2013 CFR
2013-01-01
10 Energy 3 2013-01-01 2013-01-01 false Walk-in...addition, for those WICFs with transparent reach-in doors and windows: The glass type of the doors and windows (e.g., double-pane with heat reflective...
Reduction in postprandial lipemia after walking: influence of exercise intensity.
Tsetsonis, N V; Hardman, A E
1996-10-01
This study compared the effects of low and moderate intensity walking on postprandial lipemia, holding energy expenditure constant. Nine healthy normolipidemic subjects (5 men, 4 women; age 27.7 +/- 0.9, fasting, plasma triacylglycerol 0.95 +/- 0.18 mmol.l-1, mean +/- SEM) who were physically active but not endurance-trained undertook three trials, each over 2 d, in a balanced design. On the afternoon of day 1 they either refrained from exercise (Control), walked for 3 h at low intensity (Walk low, 32 +/- 1% VO2max), or walked for 1.5 h at moderate intensity (Walk moderate, 63 +/- 1% VO2max). The following morning, after a 12-h fast, they consumed a high-fat meal (1.3 g fat, 1.2 g carbohydrate, 0.2 g protein, 76 kJ energy per kg body mass). Blood and expired air samples were obtained before the meal and for 6 h afterward. Postprandial lipemia (total area under triacylglycerol concentration vs time curve) was lower than control after low intensity walking as well as after moderate intensity walking (both P < 0.05) but did not differ between the two walking trials (Control, 8.09 +/- 1.09 mmol.l-1 h; Walk low, 5.46 +/- 0.63 mmol.l-1.h; Walk moderate, 5.53 +/- 0.58 mmol.l-1.h). The increase in energy production following the test meal did not differ between trials, but fat oxidation was increased in the fasting and postprandial states for both walking trials, compared with control (P < 0.05). PMID:8897379
Inferring Lévy walks from curved trajectories: A rescaling method
NASA Astrophysics Data System (ADS)
Tromer, R. M.; Barbosa, M. B.; Bartumeus, F.; Catalan, J.; da Luz, M. G. E.; Raposo, E. P.; Viswanathan, G. M.
2015-08-01
An important problem in the study of anomalous diffusion and transport concerns the proper analysis of trajectory data. The analysis and inference of Lévy walk patterns from empirical or simulated trajectories of particles in two and three-dimensional spaces (2D and 3D) is much more difficult than in 1D because path curvature is nonexistent in 1D but quite common in higher dimensions. Recently, a new method for detecting Lévy walks, which considers 1D projections of 2D or 3D trajectory data, has been proposed by Humphries et al. The key new idea is to exploit the fact that the 1D projection of a high-dimensional Lévy walk is itself a Lévy walk. Here, we ask whether or not this projection method is powerful enough to cleanly distinguish 2D Lévy walk with added curvature from a simple Markovian correlated random walk. We study the especially challenging case in which both 2D walks have exactly identical probability density functions (pdf) of step sizes as well as of turning angles between successive steps. Our approach extends the original projection method by introducing a rescaling of the projected data. Upon projection and coarse-graining, the renormalized pdf for the travel distances between successive turnings is seen to possess a fat tail when there is an underlying Lévy process. We exploit this effect to infer a Lévy walk process in the original high-dimensional curved trajectory. In contrast, no fat tail appears when a (Markovian) correlated random walk is analyzed in this way. We show that this procedure works extremely well in clearly identifying a Lévy walk even when there is noise from curvature. The present protocol may be useful in realistic contexts involving ongoing debates on the presence (or not) of Lévy walks related to animal movement on land (2D) and in air and oceans (3D).
Environmental Correlates of Recreational Walking in the Neighborhood.
Nehme, Eileen K; Oluyomi, Abiodun O; Calise, Tamara Vehige; Kohl, Harold W
2016-01-01
Purpose . To assess environmental correlates of neighborhood recreational walking. Design . The study used a cross-sectional survey. Setting . The study was conducted in the local community. Subjects . Participants were adults who recently relocated and walk for recreation in their current neighborhood. Measures . The outcome measure was participant-reported neighborhood recreational walking in participants' prior neighborhood. Exposure measures were (1) participant-reported social and environmental characteristics of the prior neighborhood and (2) geographic information system-derived environmental characteristics assessed within a buffer around participant's prior address. Analysis . Participants reporting current neighborhood recreational walking (n = 231) were characterized by whether they walked for recreation in their prior neighborhood. Associations between neighborhood characteristics and neighborhood recreational walking were assessed using logistic regression. Results . Neighborhood recreational walking was associated with perceptions of the presence of recreational facilities (odds ratio [OR] = 2.49, 95% confidence interval [CI] = 1.29-4.84), interesting things to see (OR = 2.82, 95% CI = 1.46-5.45), and others being active (OR = 3.56, 95% CI = 1.80-7.05), and was inversely associated with concerns about crime (OR = .40, 95% CI = .20-.77) and traffic (OR = .43, 95% CI = .22-.87). This behavior was associated with objectively measured presence of walking trails (OR = 3.58, 95% CI = 1.07-4.46), percentage of street length with speed limits ?25 mph (OR = 1.31 for 10% increase, 95% CI = 1.08-1.61), and percentage of tree canopy coverage (OR = 1.55 for 10% increase, 95% CI = 1.12-2.14). Conclusion . Recreational walking may be influenced by environmental factors that support a safe, enjoyable, and social experience, attributes that are not necessarily prioritized in transportation walking. Outcome and exposure specificity are important when studying recreational walking. PMID:25615703
Quantum-walk-based search and centrality
Berry, Scott D.; Wang, Jingbo B.
2010-10-15
We study the discrete-time quantum-walk-based search for a marked vertex on a graph. By considering various structures in which not all vertices are equivalent, we investigate the relationship between the successful search probability and the position of the marked vertex, in particular, its centrality. We find that the maximum value of the search probability does not necessarily increase as the marked vertex becomes more central, and we investigate an interesting relationship between the frequency of the successful search probability and the centrality of the marked vertex.
Light dilaton in walking gauge theories
Appelquist, Thomas; Bai Yang
2010-10-01
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.
Planning strategies for the Ambler walking robot
NASA Technical Reports Server (NTRS)
Wettergreen, David; Thomas, Hans; Thorpe, Chuck
1990-01-01
A hierarchy of planning strategies is proposed and explained for a walking robot called the Ambler. The hierarchy decomposes planning into levels of trajectory, gait, and footfall. An abstraction of feasible traversability allows the Ambler's trajectory planner to identify acceptable trajectories by finding paths that guarantee footfalls without specifying exactly which footfalls. Leg and body moves that achieve this trajectory can be generated by the Ambler's gait planner, which incorporates pattern constraints and measures of utility to search for the best next move. By combining constraints from the quality and details of the terrain, the Ambler's footfall planner can select footfalls that insure stability and remain within the tolerances of the gait.
A Light Dilaton in Walking Gauge Theories
Thomas Appelquist; Yang Bai
2010-12-24
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.
Decoherence in quantum walks and quantum computers
Hines, Andrew P
2007-01-01
Decoherence is the major stumbling block in the realization of a large-scale quantum computer. Ingenious methods have been devised to overcome decoherence, but their success has been proven only for over-simplified models of system-environment interaction. Whether such methods will be reliable in the face of more realistic models is a fundamental open question. In this partly pedagogical article, we study two toy models of quantum information processing, using the language of \\emph{quantum walks}. Decoherence is incorporated in 3 ways - by coupling to a noisy `projective measurement' system, and by coupling to oscillator and spin baths.
Novel Image Encryption based on Quantum Walks
Yang, Yu-Guang; Pan, Qing-Xiang; Sun, Si-Jia; Xu, Peng
2015-01-01
Quantum computation has achieved a tremendous success during the last decades. In this paper, we investigate the potential application of a famous quantum computation model, i.e., quantum walks (QW) in image encryption. It is found that QW can serve as an excellent key generator thanks to its inherent nonlinear chaotic dynamic behavior. Furthermore, we construct a novel QW-based image encryption algorithm. Simulations and performance comparisons show that the proposal is secure enough for image encryption and outperforms prior works. It also opens the door towards introducing quantum computation into image encryption and promotes the convergence between quantum computation and image processing. PMID:25586889
Configuration Space for Random Walk Dynamics
Bernd A. Berg; Ulrich H. E. Hansmann
1998-06-10
Applied to statistical physics models, the random cost algorithm enforces a Random Walk (RW) in energy (or possibly other thermodynamic quantities). The dynamics of this procedure is distinct from fixed weight updates. The probability for a configuration to be sampled depends on a number of unusual quantities, which are explained in this paper. This has been overlooked in recent literature, where the method is advertised for the calculation of canonical expectation values. We illustrate these points for the $2d$ Ising model. In addition, we proof a previously conjectured equation which relates microcanonical expectation values to the spectral density.
Scalable networks for discrete quantum random walks
Fujiwara, S.; Osaki, H.; Buluta, I.M.; Hasegawa, S.
2005-09-15
Recently, quantum random walks (QRWs) have been thoroughly studied in order to develop new quantum algorithms. In this paper we propose scalable quantum networks for discrete QRWs on circles, lines, and also in higher dimensions. In our method the information about the position of the walker is stored in a quantum register and the network consists of only one-qubit rotation and (controlled){sup n}-NOT gates, therefore it is purely computational and independent of the physical implementation. As an example, we describe the experimental realization in an ion-trap system.
Vertical engine for walk behind lawn mower
Isaka, Y.; Oguri, K.
1988-03-01
This patent describes a lawn mower or other similar walk behind type of implement that is designed to be operated in a normally erect position and which is tilted to the side for servicing. An engine is provided for the lawn mower having an output shaft rotatable about a vertically extending axis. The engine includes a lubricating system incorporating a crankcase in which the engine output shaft rotates and a crankcase ventilating system. The crankcase ventilating system is designed so as to prevent lubricant from flowing into the induction system when the engine is tilted on its side.
Intermittency for branching walks with heavy tails
A. Getan; S. Molchanov; B. Vainberg
2015-09-25
Branching random walks on multidimensional lattice with heavy tails and a constant branching rate are considered. It is shown that under these conditions (heavy tails and constant rate), the front propagates exponentially fast, but the particles inside of the front are distributed very non-uniformly. The particles exhibit intermittent behavior in a large part of the region behind the front (i.e., the particles are concentrated only in very sparse spots there). The zone of non-intermittency (were particles are distributed relatively uniformly) extends with a power rate. This rate is found.
Behavioral and Neural Correlates of Imagined Walking and Walking-While-Talking in the Elderly
Blumen, Helena M.; Holtzer, Roee; Brown, Lucy L.; Gazes, Yunglin; Verghese, Joe
2014-01-01
Cognition is important for locomotion and gait decline increases the risk for morbidity, mortality, cognitive decline, and dementia. Yet, the neural correlates of gait are not well established, because most neuroimaging methods cannot image the brain during locomotion. Imagined gait protocols overcome this limitation. This study examined the behavioral and neural correlates of a new imagined gait protocol that involved imagined walking (iW), imagined talking (iT), and imagined walking-while-talking (iWWT). In Experiment 1, 82 cognitively-healthy older adults (M = 80.45) walked (W), iW, walked while talking (WWT) and iWWT. Real and imagined walking task times were strongly correlated, particularly real and imagined dual-task times (WWT and iWWT). In Experiment 2, 33 cognitively-healthy older adults (M = 73.03) iW, iT, and iWWT during functional Magnetic Resonance Imaging. A multivariate Ordinal Trend (OrT) Covariance analysis identified a pattern of brain regions that: 1) varied as a function of imagery task difficulty (iW, iT and iWWT), 2) involved cerebellar, precuneus, supplementary motor and other prefrontal regions, and 3) were associated with kinesthetic imagery ratings and behavioral performance during actual WWT. This is the first study to compare the behavioral and neural correlates of imagined gait in single and dual-task situations, an issue that is particularly relevant to elderly populations. These initial findings encourage further research and development of this imagined gait protocol as a tool for improving gait and cognition among the elderly. PMID:24522972
An Analysis of Random-Walk Cuckoo Hashing Alan Frieze
Frieze, Alan
An Analysis of Random-Walk Cuckoo Hashing Alan Frieze , P´all Melsted Department of Mathematical a polylogarithmic bound that holds with high probability on the insertion time for cuckoo hashing under the random-walk insertion method. Cuckoo hashing provides a useful methodology for building practical, high-performance hash
Robust Execution of Temporally Flexible Plans for Bipedal Walking Devices
Williams, Brian C.
walking machine. An example task for such a system is to walk to a soccer ball and kick it, as shown the ball is close enough. If the biped encounters a force disturbance, it must compensate in some way, but also takes into account detailed dynamic limitations. a. b. Fig. 1 a. kicking soccer ball, b. trip
Walking in Beauty: An American Indian Perspective on Social Justice
ERIC Educational Resources Information Center
Eason, Evan Allen; Robbins, Rockey
2012-01-01
The purpose of this article is to introduce "walking in beauty," an American Indian spiritual perspective related to social justice that emphasizes beauty, harmony, connectedness/unity of experience, and imagination. Walking in beauty includes 3 processes: embodiment, creativity, and appreciation of the sublime. Recommendations are offered for…
Walking Humanoids for Robotics Research Krister Wolff Peter Nordin
Fernandez, Thomas
. Microphones, cameras and touch sensors guide the robot. The imminent goals are to walk upright and to navigateWalking Humanoids for Robotics Research Krister Wolff Peter Nordin Dept. of Physical Resource, nordin}@fy.chalmers.se Abstract We present three humanoid robots aimed as platforms for research
Walking on water: why your feet get wet
NASA Astrophysics Data System (ADS)
Shelley, Michael; Fontana, Jake; Palffy-Muhoray, Peter
2009-03-01
Walking on wet pavement during or after heavy rain results in wet shoes, and often, wet feet. We describe a peculiar transport process associated with walking on wet surfaces which results in the vamps, and frequently, the insides, of shoes getting wet. We discuss details of this process and compare experimental results with simple model predictions. Strategies for keeping feet dry will be considered.
Chinese City Children and Youth's Walking Behavior
ERIC Educational Resources Information Center
Quan, Minghui; Chen, Peijie; Zhuang, Jie; Wang, Chao
2013-01-01
Purpose: Although walking has been demonstrated as one of the best forms for promoting physical activity (PA), little is known about Chinese city children and youth's walking behavior. The purpose of this study was therefore to assess ambulatory PA behavior of Chinese city children and youth. Method: The daily steps of 2,751 children and…
Sequencing a Genome by Walking With Clone-end Sequences
Sequencing a Genome by Walking With Clone-end Sequences: A Mathematical Analysis Serafim Batzoglou-insert clones (such as bacterial artificial chromosomes (BACs)) and then (ii) to take successive 'walking' steps by selecting and sequencing minimally overlapping clones, using information such as clone-end sequences
BIASED RANDOM WALKS ON GALTON-WATSON TREES WITH LEAVES
Gantert, Nina
BIASED RANDOM WALKS ON GALTON-WATSON TREES WITH LEAVES G´ERARD BEN AROUS, ALEXANDER FRIBERGH, NINA GANTERT, AND ALAN HAMMOND Abstract. We consider a biased random walk Xn on a Galton-Watson tree. Key tools for the proof are the classical Harris decomposition for Galton-Watson trees, a new variant
Infant Language Development Is Related to the Acquisition of Walking
ERIC Educational Resources Information Center
Walle, Eric A.; Campos, Joseph J.
2014-01-01
The present investigation explored the question of whether walking onset is related to infant language development. Study 1 used a longitudinal design (N = 44) to assess infant locomotor and language development every 2 weeks from 10 to 13.5 months of age. The acquisition of walking was associated with a significant increase in both receptive and…
Recycling Energy to Restore Impaired Ankle Function during Human Walking
Collins, Steven H.
Recycling Energy to Restore Impaired Ankle Function during Human Walking Steven H. Collins1 that captures some of the energy that is normally dissipated by the leg and ``recycles'' it as positive ankle walking. Energy recycling restored ankle push-off to normal and reduced the net metabolic energy penalty
Stably Extending Two-Dimensional Bipedal Walking to Three Dimensions
Ames, Aaron
. Gregg Abstract-- In this paper we develop a feedback control law that results in stable walking gaits is to obtain stable walking gaits, i.e., to prove the existence of stable periodic orbits and/or to develop control laws that create such orbits. Due to the inherent complexity of bipedal robots, many approaches
The Fibonacci quantum walk and its cassical trace map
Alejandro Romanelli
2008-02-15
We study the quantum walk in momentum space using a coin arranged in quasi-periodic sequences following a Fibonacci prescription. We build for this system a classical map based on the trace of the evolution operator. The sub-ballistic behavior of this quantum walk is connected with the power-law decay of the time correlations of the trace map.
Validity of the Nike+ device during walking and running.
Kane, N A; Simmons, M C; John, D; Thompson, D L; Bassett, D R; Basset, D R
2010-02-01
We determined the validity of the Nike+ device for estimating speed, distance, and energy expenditure (EE) during walking and running. Twenty trained individuals performed a maximal oxygen uptake test and underwent anthropometric and body composition testing. Each participant was outfitted with a Nike+ sensor inserted into the shoe and an Apple iPod nano. They performed eight 6-min stages on the treadmill, including level walking at 55, 82, and 107 m x min(-1), inclined walking (82 m x min(-1)) at 5 and 10% grades, and level running at 134, 161, and 188 m x min(-1). Speed was measured using a tachometer and EE was measured by indirect calorimetry. Results showed that the Nike+ device overestimated the speed of level walking at 55 m x min(-1) by 20%, underestimated the speed of level walking at 107 m x min(-1) by 12%, but closely estimated the speed of level walking at 82 m x min(-1), and level running at all speeds (p<0.05). Similar results were found for distance. The Nike+ device overestimated the EE of level walking by 18-37%, but closely estimated the EE of level running (p<0.05). In conclusion the Nike+ in-shoe device provided reasonable estimates of speed and distance during level running at the three speeds tested in this study. However, it overestimated EE during level walking and it did not detect the increased cost of inclined locomotion. PMID:20027538
Humanoid Robot Walking Control on Inclined Planes Utku Seven1
Yanikoglu, Berrin
Humanoid Robot Walking Control on Inclined Planes Utku Seven1 , Tunc Akbas2 , Kaan Can Fidan3 of a humanoid robot. This paper presents a study on bipedal walk on inclined planes. A Zero Moment Point (ZMP in the full-dynamics 3-D simulations. Simulations are carried out on even floor and inclined planes
Velocity-Based Stability Margins for Fast Bipedal Walking
Tedrake, Russ
Velocity-Based Stability Margins for Fast Bipedal Walking Jerry E. Pratt1 and Russ Tedrake2 1 russt@mit.edu 1 Abstract We present velocity-based stability margins for fast bipedal walking into consideration a biped's Center of Mass position and velocity, the reachable region of its swing leg, the time
On recurrence and transience of self-interacting random walks
Sousi, Perla
the walk takes also depends on the past. Recently there has been a lot of interest in random walks of Cambridge, Cambridge, UK; p.sousi@statslab.cam.ac.uk #12;Definition 1.1. Let µ1, . . . , µk be k probability
The Simple Random Walk Snake on Z^4 is Recurrent
Benjamini, Itai
2011-01-01
Consider the branching simple random walk on Z^d indexed by a critical geometric Galton-Watson tree conditioned to survive. Using the concept of unimodular random graphs, we show that the walk is recurrent if and only if d is less than or equal to 4.
Human pair walking behavior: evaluation of cooperation strategies
NASA Astrophysics Data System (ADS)
Dobramysl, Ulrich; Bodova, Katarina; Kollar, Richard; Erban, Radek
2015-03-01
Human walkers are notoriously poor at keeping a direction without external cues: Experimental work by Souman et al. with blindfolded subjects told to walk in a straight line revealed intriguing circular and spiraling trajectories, which can be approximated by a stochastic process. In this work, motivated by pair walking experiments by Miglierini et al., we introduce an analysis of various strategies employed by a pair of blindfolded walkers, who are communicating via auditory cues, to maximize their efficiency at walking straight. To this end, we characterize pairs of strategies such as free walking, side-by-side walking and unconditional following from data generated by robot pair walking experiments (using computer vision techniques) and numerical simulations. We extract the mean exit distances of walker pairs from a corridor with finite width to construct phase portraits of the walking performance. We find intriguing cooperative effects leading to non-trivial enhancements of the efficiency at walking straight. The research leading to these results has received funding from the European Research Council under the European Community's Seventh Framework Programme (FP7/2007-2013) / ERC Grant Agreement No. 239870; and from the Royal Society through a Research Grant.
Effect of Backward Walking on Attention: Possible Application on ADHD
Viggiano, Davide; Travaglio, Michele; Cacciola, Giovanna; Di Costanzo, Alfonso
2015-01-01
The human requires attentive effort as assessed in dual-task experiments. Consistently, an attentive task can modify the walking pattern and a attention deficit and hyperactivity disorder (ADHD) is accompanied by gait modifications. Here we investigated the relationships between backward walking and attentive performances in ADHD children (n=13) and healthy age-, height and weight matched controls (n=17). We evaluated the attentive/impulsive profile by means of a Go/No-Go task and the backward and forward gait parameters by step length, cadence and Froude number. Moreover, to test the causal relationship between attention and gait parameters, we trained children to walk backward. The training program consisted of 10 min backward walking session, thrice a week for two months. Results showed a significant negative correlation between Froude number during backward walking and reaction time in the Go/No-Go test. Besides, after training with backward walking control children increased their cadence by 9.3% and their Froude number by 17% during backward walking. Conversely, ADHD children did not modify their walking parameters after training, and showed a significant reduction in their number of errors in the Go/No-Go task (?49%) compared to the score before the training. These data suggest that specific physical training with attention-demanding tasks may improve attentive performance. PMID:25674550
Algebraic area enclosed by random walks on a lattice
NASA Astrophysics Data System (ADS)
Desbois, Jean
2015-10-01
We compute the moments ?ft<{A}2k\\right> of the area enclosed by an N-steps random walk on a 2D lattice. We consider separately the cases where the walk comes back to the origin or not. We also compute, for both cases, the characteristic function ?ft<{{{e}}}{{i} B A}\\right> at order 1/{N}2.
Online Pose Classification and Walking Speed Estimation using Handheld Devices
Teller, Seth
experiments as well as in natural indoor walk- ing settings. Experiments with 14 human participants to test% accuracy com- pared to 82% for previous work, and our walking speed es- timates are within 12-15% (straight/indoor handheld devices to intelligently react to their environment, they must infer user activities from raw
Developmental Psychology Sensitive Perception of a Person's Direction of Walking
Whitney, David
. (2013, January 28). Sensitive Perception of a Person's Direction of Walking by 4-Year-Old Children Perception of a Person's Direction of Walking by 4-Year-Old Children Timothy D. Sweeny, Nicole Wurnitsch-level visual areas. Even at 4 years of age, children's sensitivity approached that of adults'. This suggests
When does walking alter thinking? Age and task associated findings
Srygley, Jennifer M; Mirelman, Anat; Herman, Talia; Giladi, Nir; Hausdorff, Jeffrey M
2008-01-01
Age-associated changes in gait are exacerbated when another task is performed simultaneously. We quantified the converse, i.e., the effects of walking on cognitive abilities, and determined the role of aging and executive function (EF) in any observed changes. 276 healthy older adults and 52 healthy young adults performed three cognitive tasks, i.e., serial 7 and 3 subtractions and phoneme-monitoring, while sitting and again while walking. Among the elderly, walking decreased performance on serial 3 and 7 subtractions and the number of phonemes counted (p<0.0001), but enhanced content recall. In contrast, for the young adults, walking did not alter serial 3 subtractions, phoneme-monitoring or content recall, while serial 7 subtraction performance decreased during walking (p=0.047). Measures of EF explained the age-associated changes in performance of the cognitive task during walking. Findings in both young and old subjects underscore the idea that gait is attention-demanding and is not a purely motor task. Even young, healthy adults demonstrate decreased cognitive performance while walking, when the cognitive task is sufficiently difficult. Age-associated declines in EF apparently contribute to the difference in dual tasking abilities during walking between young and older adults. PMID:19084511
Random walks in random environment Tom Schmitz (MPI Leipzig)
Thalmaier, Anton
Random walks in random environment Tom Schmitz (MPI Leipzig) The model of random walks in random environment (RWRE) originates from physical and biological sciences and describes a random motion random variables, creating thus a "random environment" for the walker. More specifically, we only allow
Larouche, Richard; Barnes, Joel; Tremblay, Mark S
2013-01-01
Only 25-35% of Canadian children and youth regularly engage in active transportation (AT; e.g., non-motorized travel modes such as walking and cycling) to/from school. Previous research shows that distance between home and school is the strongest barrier to AT. Based on social ecological theory, we describe several strategies to overcome this barrier. At the individual level, children and youth could engage in AT to/from destinations such as parks, shops, friends' and family members' residence, and sport fields which may be located closer than their school. Parents who drive their kids to/from school could drop them within a "walkable" distance so that they can walk for the remainder of the trip. Partnerships could be developed between schools and other nearby institutions that would allow cars and buses to use their parking lot temporarily so that children could do a portion of the school trip on foot. Developing a well-connected network of sidewalks along low traffic streets can also facilitate AT. At the policy level, decisions regarding school location have a direct influence on distance. Finally, social marketing campaigns could raise awareness about strategies to incorporate AT into one's lifestyle, and encourage parents to reconsider what constitutes a "walkable" distance. PMID:24495826
Theories of bipedal walking: an odyssey.
Vaughan, Christopher L
2003-04-01
In this paper six theories of bipedal walking, and the evidence in support of the theories, are reviewed. They include: evolution, minimising energy consumption, maturation in children, central pattern generators, linking control and effect, and robots on two legs. Specifically, the six theories posit that: (1) bipedalism is the fundamental evolutionary adaptation that sets hominids--and therefore humans--apart from other primates; (2) locomotion is the translation of the centre of gravity along a pathway requiring the least expenditure of energy; (3) when a young child takes its first few halting steps, his or her biomechanical strategy is to minimise the risk of falling; (4) a dedicated network of interneurons in the spinal cord generates the rhythm and cyclic pattern of electromyographic signals that give rise to bipedal gait; (5) bipedal locomotion is generated through global entrainment of the neural system on the one hand, and the musculoskeletal system plus environment on the other; and (6) powered dynamic gait in a bipedal robot can be realised only through a strategy which is based on stability and real-time feedback control. The published record suggests that each of the theories has some measure of support. However, it is important to note that there are other important theories of locomotion which have not been covered in this review. Despite such omissions, this odyssey has explored the wide spectrum of bipedal walking, from its origins through to the integration of the nervous, muscular and skeletal systems. PMID:12600342
Random walk with priorities in communicationlike networks
NASA Astrophysics Data System (ADS)
Bastas, Nikolaos; Maragakis, Michalis; Argyrakis, Panos; ben-Avraham, Daniel; Havlin, Shlomo; Carmi, Shai
2013-08-01
We study a model for a random walk of two classes of particles (A and B). Where both species are present in the same site, the motion of A's takes precedence over that of B's. The model was originally proposed and analyzed in Maragakis [Phys. Rev. EPLEEE81539-375510.1103/PhysRevE.77.020103 77, 020103(R) (2008)]; here we provide additional results. We solve analytically the diffusion coefficients of the two species in lattices for a number of protocols. In networks, we find that the probability of a B particle to be free decreases exponentially with the node degree. In scale-free networks, this leads to localization of the B's at the hubs and arrest of their motion. To remedy this, we investigate several strategies to avoid trapping of the B's, including moving an A instead of the hindered B, allowing a trapped B to hop with a small probability, biased walk toward non-hub nodes, and limiting the capacity of nodes. We obtain analytic results for lattices and networks, and we discuss the advantages and shortcomings of the possible strategies.
The 1991-1992 walking robot design
NASA Technical Reports Server (NTRS)
Azarm, Shapour; Dayawansa, Wijesurija; Tsai, Lung-Wen; Peritt, Jon
1992-01-01
The University of Maryland Walking Machine team designed and constructed a robot. This robot was completed in two phases with supervision and suggestions from three professors and one graduate teaching assistant. Bob was designed during the Fall Semester 1991, then machined, assembled, and debugged in the Spring Semester 1992. The project required a total of 4,300 student hours and cost under $8,000. Mechanically, Bob was an exercise in optimization. The robot was designed to test several diverse aspects of robotic potential, including speed, agility, and stability, with simplicity and reliability holding equal importance. For speed and smooth walking motion, the footpath contained a long horizontal component; a vertical aspect was included to allow clearance of obstacles. These challenges were met with a leg design that utilized a unique multi-link mechanism which traveled a modified tear-drop footpath. The electrical requirements included motor, encoder, and voice control circuitry selection, manual controller manufacture, and creation of sensors for guidance. Further, there was also a need for selection of the computer, completion of a preliminary program, and testing of the robot.
Checklist and Pollard Walk butterfly survey methods on public lands
Royer, R.A.; Austin, J.E.; Newton, W.E.
1998-01-01
Checklist and Pollard Walk butterfly survey methods were contemporaneously applied to seven public sites in North Dakota during the summer of 1995. Results were compared for effect of method and site on total number of butterflies and total number of species detected per hour. Checklist searching produced significantly more butterfly detections per hour than Pollard Walks at all sites. Number of species detected per hour did not differ significantly either among sites or between methods. Many species were detected by only one method, and at most sites generalist and invader species were more likely to be observed during checklist searches than during Pollard Walks. Results indicate that checklist surveys are a more efficient means for initial determination of a species list for a site, whereas for long-term monitoring the Pollard Walk is more practical and statistically manageable. Pollard Walk transects are thus recommended once a prairie butterfly fauna has been defined for a site by checklist surveys.
Phase transition in random adaptive walks on correlated fitness landscapes
NASA Astrophysics Data System (ADS)
Park, Su-Chan; Szendro, Ivan G.; Neidhart, Johannes; Krug, Joachim
2015-04-01
We study biological evolution on a random fitness landscape where correlations are introduced through a linear fitness gradient of strength c . When selection is strong and mutations rare the dynamics is a directed uphill walk that terminates at a local fitness maximum. We analytically calculate the dependence of the walk length on the genome size L . When the distribution of the random fitness component has an exponential tail, we find a phase transition of the walk length D between a phase at small c , where walks are short (D ˜lnL ) , and a phase at large c , where walks are long (D ˜L ) . For all other distributions only a single phase exists for any c >0 . The considered process is equivalent to a zero temperature Metropolis dynamics for the random energy model in an external magnetic field, thus also providing insight into the aging dynamics of spin glasses.
Radar walk detection in the apartments of elderly.
Phillips, Calvin E; Keller, James; Popescu, Mihail; Skubic, Marjorie; Rantz, Marilyn J; Cuddihy, Paul E; Yardibi, Tarik
2012-01-01
Seniors want to live more independent lifestyles. This comes with some risks including dwindling health and major injuries due to falling. A factor that has been studied and seen to have a correlation to fall risk is change in gait speed. Our goal is to create a passive system that monitors the gait of elderly so that assessments can be given by caregivers if gait changes do occur. This paper will cover a method of using pulse-Doppler radar to detect when walks occur. In unscripted living environments, we are able to detect valid walks. The system does miss walks during the day, but when walks are detected, they are actually valid walks 91.8% of the time using a large data base of radar signals captured in living environments. PMID:23367262
Simulation of energy consumption for quadruped walking vehicle
NASA Astrophysics Data System (ADS)
Lei, Jingtao; Gao, Feng; Xu, Guoyan
2006-11-01
Simulation of energy consumption for walking vehicle is one of the basic way to preliminarily estimate the energy that will be consumed before constructing the real vehicle, providing basis for the design of vehicle to minish energy consumption. One of the most influential factors of the accuracy dynamic simulation is the appropriate contact model between leg and ground. In this paper, we adopt virtual prototyping technique to develop the dynamic modeling of a quadruped walking vehicle considering contact force between legs and ground during walking, finish simulation of dynamics and obtain dynamics characteristics, investigate the effects of different contact condition and the energy consumption. The purpose is to analyze the relationship between energy consumption and relevant influence factors, and the energy efficiency during walking is discussed with different walking velocity, strokes, duty factors and different contact material. Moreover contact force is obtained from simulations. Commercial ADAMS package is used.
Quantum walk coherences on a dynamical percolation graph
NASA Astrophysics Data System (ADS)
Elster, Fabian; Barkhofen, Sonja; Nitsche, Thomas; Novotný, Jaroslav; Gábris, Aurél; Jex, Igor; Silberhorn, Christine
2015-08-01
Coherent evolution governs the behaviour of all quantum systems, but in nature it is often subjected to influence of a classical environment. For analysing quantum transport phenomena quantum walks emerge as suitable model systems. In particular, quantum walks on percolation structures constitute an attractive platform for studying open system dynamics of random media. Here, we present an implementation of quantum walks differing from the previous experiments by achieving dynamical control of the underlying graph structure. We demonstrate the evolution of an optical time-multiplexed quantum walk over six double steps, revealing the intricate interplay between the internal and external degrees of freedom. The observation of clear non-Markovian signatures in the coin space testifies the high coherence of the implementation and the extraordinary degree of control of all system parameters. Our work is the proof-of-principle experiment of a quantum walk on a dynamical percolation graph, paving the way towards complex simulation of quantum transport in random media.
Martin, Ralph R.
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
2013-01-01
Background Walking interventions have been shown to have a positive impact on physical activity (PA) levels, health and wellbeing for adult and older adult populations. There has been very little work carried out to explore the effectiveness of walking interventions for adults with intellectual disabilities. This paper will provide details of the Walk Well intervention, designed for adults with intellectual disabilities, and a randomised controlled trial (RCT) to test its effectiveness. Methods/design This study will adopt a RCT design, with participants allocated to the walking intervention group or a waiting list control group. The intervention consists of three PA consultations (baseline, six weeks and 12 weeks) and an individualised 12 week walking programme. A range of measures will be completed by participants at baseline, post intervention (three months from baseline) and at follow up (three months post intervention and six months from baseline). All outcome measures will be collected by a researcher who will be blinded to the study groups. The primary outcome will be steps walked per day, measured using accelerometers. Secondary outcome measures will include time spent in PA per day (across various intensity levels), time spent in sedentary behaviour per day, quality of life, self-efficacy and anthropometric measures to monitor weight change. Discussion Since there are currently no published RCTs of walking interventions for adults with intellectual disabilities, this RCT will examine if a walking intervention can successfully increase PA, health and wellbeing of adults with intellectual disabilities. Trial registration ISRCTN: ISRCTN50494254 PMID:23816316
an increase in muscle activation, then a corresponding decrease in the GRFs during the propulsion phase would and running at the PTS revealed that all lower extremity muscle forces increased with walking speed, except the ankle plantar flexors. Despite an increase in muscle activation with walking speed, the gastrocnemius
WalkSafe: A Pedestrian Safety App for Mobile Phone Users Who Walk and Talk While Crossing Roads
Campbell, Andrew T.
WalkSafe: A Pedestrian Safety App for Mobile Phone Users Who Walk and Talk While Crossing Roads.cardone, antonio.corradi }@unibo.it ABSTRACT Research in social science has shown that mobile phone con- versations distract users, presenting a significant impact to pedestrian safety; for example, a mobile phone user deep
75 FR 55067 - Energy Conservation Program: Test Procedures for Walk-In Coolers and Walk-In Freezers
Federal Register 2010, 2011, 2012, 2013, 2014
2010-09-09
...Definition of Walk-In Cooler or Freezer: Temperature...EER of walk-in (cooler or freezer), Btu...anti-sweat or anti-freeze application); lights...temperature in the ``cold side'' of the envelope...Ceiling Panels (i) Cooler conditions, Panel...
Tagawa, Y; Shiba, N; Matsuo, S; Yamashita, T
2000-11-01
This paper proposes new models of diseased joints and evaluates the effectiveness of walking aids such as a cane and a brace for compensating for lost functions due to joint disorders. The ZMJ concept described in the previous work (Yamashita and Tagawa, 1988. In: Radharaman (Ed.), Robotics and Factories of the Future'87. Springer, New York, pp. 670-677) is modified into three joint models as follows: a passive element joint (PEJ) which has a spring at the diseased joint; a constrained range joint (CRJ), the motion of which stays within some constrained relative angle; a partial moment joint (PMJ) which can produce a partial amount of the moment produced about the joint in normal walking. A cane can enlarge a supporting area and adjust the posture of the upper torso to be upright. An ischial weight-bearing brace is effective for conservative management of hip disorders by reducing a load to the joint (Shiba et al., 1998. Clinical Orthopaedics and Related Research 351, 149-157). Walking aids like a cane or brace have been conveniently used by the handicapped. Abnormal walking was simulated for each joint model. Dynamic effects of a cane and a brace on abnormal walking were examined by the multi-body walking model. PMID:10940399
Longo, Alberto; Hutchinson, W George; Hunter, Ruth F; Tully, Mark A; Kee, Frank
2015-10-01
Walking is the most common form of moderate-intensity physical activity among adults, is widely accessible and especially appealing to obese people. Most often policy makers are interested in valuing the effect on walking of changes in some characteristics of a neighbourhood, the demand response for walking, of infrastructure changes. A positive demand response to improvements in the walking environment could help meet the public health target of 150 min of at least moderate-intensity physical activity per week. We model walking in an individual's local neighbourhood as a 'weak complement' to the characteristics of the neighbourhood itself. Walking is affected by neighbourhood characteristics, substitutes, and individual's characteristics, including their opportunity cost of time. Using compensating variation, we assess the economic benefits of walking and how walking behaviour is affected by improvements to the neighbourhood. Using a sample of 1209 respondents surveyed over a 12 month period (Feb 2010-Jan 2011) in East Belfast, United Kingdom, we find that a policy that increased walkability and people's perception of access to shops and facilities would lead to an increase in walking of about 36 min/person/week, valued at £13.65/person/week. When focussing on inactive residents, a policy that improved the walkability of the area would lead to guidelines for physical activity being reached by only 12.8% of the population who are currently inactive. Additional interventions would therefore be needed to encourage inactive residents to achieve the recommended levels of physical activity, as it appears that interventions that improve the walkability of an area are particularly effective in increasing walking among already active citizens, and, among the inactive ones, the best response is found among healthier, younger and wealthier citizens. PMID:26347960
Women with fibromyalgia walk with an altered muscle synergy.
Pierrynowski, Michael R; Tiidus, Peter M; Galea, Victoria
2005-11-01
Most individuals can use different movement and muscle recruitment patterns to perform a stated task but often only one pattern is selected which optimizes an unknown global objective given the individual's neuromusculoskeletal characteristics. Patients with fibromyalgia syndrome (FS), characterized by their chronic pain, reduced physical work capacity and muscular fatigue, could exhibit a different control signature compared to asymptomatic control volunteers (CV). To test this proposal, 22 women with FS, and 11 CV, were assessed in a gait analysis laboratory. Each subject walked repeatedly at self-selected slow, comfortable, and fast walking speeds. The gait analysis provided, for each walk, each subject's stride time, length, and velocity, and ground reaction force, and lower extremity joint kinematics, moments and powers. The data were then anthropometrically scaled and velocity normalized to reduce the influence of subject mass, leg length, and walking speed on the measured gait outcomes. Similarities and differences in the two groups' scaled and normalized gait patterns were then determined. Results show that FS and CV walk with externally similar stride lengths, times, and velocities, and joint angles and ground reaction forces but they use internally different muscle recruitment patterns. Specifically, FS preferentially power gait using their hip flexors instead of their ankle plantarflexors. Interestingly, CV use a similar muscle fatiguing recruitment pattern to walk fast which parallels the common complaint of fatigue reported by FS walking at comfortable speed. PMID:16214660
Survey of Korean pedestrians' natural preference for walking directions.
Jung, Hwa S; Jung, Hyung-Shik
2013-11-01
The primary objective of this study was to investigate the stereotypes of Koreans regarding preferred walking directions when encountering various public walking facilities, and to provide useful information to pedestrians and traffic policy legislators. To this end, this study was conducted in two phases. In the first phase, we conducted observational research on pedestrians' walking directions in ten different situations. In the second phase, six hundred Korean male and female subjects were selected to investigate the various statistics about their preferred walking directions and their employment characteristics in diverse walking facilities. The results showed that 59.3% abided by the Left-side Traffic rule while 40.7% abided by the Right-side rule. On the contrary, 73.7% of respondents showed preferences to the Right-side Traffic rule. Moreover, right-handed people showed strong tendencies to walk on the right side of the road and vice versa, hence suggesting that the direction people naturally prefer in walking should be a crucial determinant when regulating traffic policies. PMID:23664206
Clark, David J.
2015-01-01
Automaticity is a hallmark feature of walking in adults who are healthy and well-functioning. In the context of walking, “automaticity” refers to the ability of the nervous system to successfully control typical steady state walking with minimal use of attention-demanding executive control resources. Converging lines of evidence indicate that walking deficits and disorders are characterized in part by a shift in the locomotor control strategy from healthy automaticity to compensatory executive control. This is potentially detrimental to walking performance, as an executive control strategy is not optimized for locomotor control. Furthermore, it places excessive demands on a limited pool of executive reserves. The result is compromised ability to perform basic and complex walking tasks and heightened risk for adverse mobility outcomes including falls. Strategies for rehabilitation of automaticity are not well defined, which is due to both a lack of systematic research into the causes of impaired automaticity and to a lack of robust neurophysiological assessments by which to gauge automaticity. These gaps in knowledge are concerning given the serious functional implications of compromised automaticity. Therefore, the objective of this article is to advance the science of automaticity of walking by consolidating evidence and identifying gaps in knowledge regarding: (a) functional significance of automaticity; (b) neurophysiology of automaticity; (c) measurement of automaticity; (d) mechanistic factors that compromise automaticity; and (e) strategies for rehabilitation of automaticity. PMID:25999838
Association between teething and independent walking in healthy children.
Kaymaz, Nazan; Y?ld?r?m, ?ule; Cevizci, Sibel; Çimen, Mehmet; Topalo?lu, Naci; Binneto?lu, Fatih Köksal; Tekin, Mustafa; Özmert, Elif Nursel
2015-01-01
Developing teeth provide a reliable indication of maturation and biological age. The objective of this study was to establish whether there is any association between the time of emergence of the first primary tooth and the time when independent walking occurs. A cross-sectional study was conducted with a sample of 206 healthy children (95 girls and 111 boys) aged 12 to 60 (mean: 29.79±0.66) months who were able to walk independently. The study was conducted using a questionnaire that was filled out by the parents. The first primary tooth emerged at 6.86±0.14 (min: 3-max: 13) months; the mean independent walking time was 12.58±2.15 (min: 8.50-max: 24.00) months. There was no correlation between the first teething and independent walking times (r=0.045, p=0.523). Factors such as breastfeeding status, intake of vitamins, walker usage and body mass index were found not to affect the time of either emergence of the first deciduous tooth or independent walking. To the best of our knowledge, this is the first paper in literature to have researched the relationship between the time of emergence of the first deciduous tooth and that of independent walking. It should be explained to parents that there is no relationship between the two in order to resolve anxiety when their child acquires a tooth but does not walk, or vice versa. PMID:26613221
Quantum walk, entanglement and thermodynamic laws
NASA Astrophysics Data System (ADS)
Romanelli, Alejandro
2015-09-01
We consider a special dynamics of a quantum walk (QW) on a line. The walker, initially localized at the origin of the line with arbitrary chirality, evolves to an asymptotic stationary state. In this stationary state a measurement is performed and the state resulting from this measurement is used to start a second QW evolution to achieve a second asymptotic stationary state. In previous works, we developed the thermodynamics associated with the entanglement between the coin and position degrees of freedom in the QW. Here we study the application of the first and second laws of thermodynamics to the process between the two stationary states mentioned above. We show that: (i) the entropy change has upper and lower bounds that are obtained analytically as functions of the initial conditions. (ii) the energy change is associated to a heat-transfer process.
Thermodynamics of N-dimensional quantum walks
NASA Astrophysics Data System (ADS)
Romanelli, Alejandro; Donangelo, Raul; Portugal, Renato; Marquezino, Franklin de Lima
2014-08-01
The entanglement between the position and the coin state of an N-dimensional quantum walker is shown to lead to a thermodynamic theory. The entropy, in this thermodynamics, is associated with the reduced density operator for the evolution of chirality, taking a partial trace over positions. From the asymptotic reduced density matrix it is possible to define thermodynamic quantities, such as the asymptotic entanglement entropy, temperature, and Helmholz free energy. We study in detail the case of a two-dimensional quantum walk, in the case of two initial conditions: a nonseparable coin-position initial state and a separable one. The resulting entanglement temperature is presented as a function of the parameters of the system and those of the initial conditions.
Scalar Mesons in Holographic Walking Technicolor
Lilia Anguelova; Peter Suranyi; L. C. Rohana Wijewardhana
2012-05-09
We study the spectrum of scalar mesons in the holographic dual of walking technicolor, obtained by embedding D7 - anti-D7 probe branes in a certain type IIB background. The scalar mesons arise from fluctuations of the probe techniflavour branes and complement the (axial-)vector meson spectra that we investigated in earlier work. By explicitly finding the spectrum of scalar masses, we show that the nonsupersymmetric D7 - anti-D7 embedding is stable with respect to such fluctuations. Interestingly, it turns out that the mass splitting between the scalar and vector meson spectra is of subleading order in a small parameter expansion. It is noteworthy that this near-degeneracy may not be entirely due to a small amount of supersymmetry breaking and thus could indicate the presence of some other (approximate) symmetry in the problem.
Discrete time quantum walks on percolation graphs
NASA Astrophysics Data System (ADS)
Kollár, Bálint; Novotný, Jaroslav; Kiss, Tamás; Jex, Igor
2014-05-01
Randomly breaking connections in a graph alters its transport properties, a model used to describe percolation. In the case of quantum walks, dynamic percolation graphs represent a special type of imperfections, where the connections appear and disappear randomly in each step during the time evolution. The resulting open system dynamics is hard to treat numerically in general. We shortly review the literature on this problem. We then present our method to solve the evolution on finite percolation graphs in the long time limit, applying the asymptotic methods concerning random unitary maps. We work out the case of one-dimensional chains in detail and provide a concrete, step-by-step numerical example in order to give more insight into the possible asymptotic behavior. The results about the case of the two-dimensional integer lattice are summarized, focusing on the Grover-type coin operator.
The subtle nature of financial random walks
NASA Astrophysics Data System (ADS)
Bouchaud, Jean-Philippe
2005-06-01
We first review the most important "stylized facts" of financial time series, that turn out to be, to a large extent, universal. We then recall how the multifractal random walk of Bacry, Muzy, and Delour generalizes the standard model of financial price changes and accounts in an elegant way for many of their empirical properties. In a second part, we provide empirical evidence for a very subtle compensation mechanism that underlies the random nature of price changes. This compensation drives the market close to a critical point, that may explain the sensitivity of financial markets to small perturbations, and their propensity to enter bubbles and crashes. We argue that the resulting unpredictability of price changes is very far from the neoclassical view that markets are informationally efficient.
Random time averaged diffusivities for Lévy walks
NASA Astrophysics Data System (ADS)
Froemberg, D.; Barkai, E.
2013-07-01
We investigate a Lévy walk alternating between velocities ±v0 with opposite sign. The sojourn time probability distribution at large times is a power law lacking its mean or second moment. The first case corresponds to a ballistic regime where the ensemble averaged mean squared displacement (MSD) at large times is ?x2? ? t2, the latter to enhanced diffusion with ?x2? ? t?, 1 < ? < 2. The correlation function and the time averaged MSD are calculated. In the ballistic case, the deviations of the time averaged MSD from a purely ballistic behavior are shown to be distributed according to a Mittag-Leffler density function. In the enhanced diffusion regime, the fluctuations of the time averages MSD vanish at large times, yet very slowly. In both cases we quantify the discrepancy between the time averaged and ensemble averaged MSDs.
Random walks in directed modular networks
NASA Astrophysics Data System (ADS)
Comin, Cesar H.; Viana, Mateus P.; Antiqueira, Lucas; Costa, Luciano da F.
2014-12-01
Because diffusion typically involves symmetric interactions, scant attention has been focused on studying asymmetric cases. However, important networked systems underlain by diffusion (e.g. cortical networks and WWW) are inherently directed. In the case of undirected diffusion, it can be shown that the steady-state probability of the random walk dynamics is fully correlated with the degree, which no longer holds for directed networks. We investigate the relationship between such probability and the inward node degree, which we call efficiency, in modular networks. Our findings show that the efficiency of a given community depends mostly on the balance between its ingoing and outgoing connections. In addition, we derive analytical expressions to show that the internal degree of the nodes does not play a crucial role in their efficiency, when considering the Erd?s-Rényi and Barabási-Albert models. The results are illustrated with respect to the macaque cortical network, providing subsidies for improving transportation and communication systems.
Transience of Edge-Reinforced Random Walk
NASA Astrophysics Data System (ADS)
Disertori, Margherita; Sabot, Christophe; Tarrès, Pierre
2015-10-01
We show transience of the edge-reinforced random walk (ERRW) for small reinforcement in dimension . This proves the existence of a phase transition between recurrent and transient behavior, thus solving an open problem stated by Diaconis in 1986. The argument adapts the proof of quasi-diffusive behavior of the supersymmetric (SuSy) hyperbolic model for fixed conductances by Disertori et al. (Commun Math Phys 300:435-486, 2010), using the representation of ERRW as a mixture of vertex-reinforced jump processes (VRJP) with independent gamma conductances, and the interpretation of the limit law of VRJP as a SuSy hyperbolic sigma model developed by Sabot and Tarrès (J Eur Math Soc, arXiv:1111.3991, 2015).
Short Communication New Spiroplasma in parasitic Leptus mites and their Agathemera walking stick
Clayton, Dale H.
Short Communication New Spiroplasma in parasitic Leptus mites and their Agathemera walking stick (Leptus sayi; Leptus lomani) and their Agathemera walking stick hosts. In walking sticks Spiroplasmas were detected by exploratory PCR screens in understudied parasitic Leptus mites (Leptidae) and their walking
Walking Control Algorithm of Biped Humanoid Robot on Uneven and Inclined Floor
Walking Control Algorithm of Biped Humanoid Robot on Uneven and Inclined Floor Jung-Yup Kim, Ill describes walking control algorithm for the stable walking of a biped humanoid robot on an uneven and inclined floor. Many walking control techniques have been developed based on the assumption
VELOCITY-DEPENDENT DYNAMIC CURVATURE GAIN FOR REDIRECTED WALKING 1 Velocity-Dependent Dynamic Curvature Gain for Redirected Walking Christian T. Neth, Jan L. Souman, David Engel, Uwe Kloos, Heinrich H. B¨ulthoff and Betty J. Mohler Abstract--Redirected walking techniques allow people to walk
Identifying Belief-Based Targets for the Promotion of Leisure-Time Walking
ERIC Educational Resources Information Center
Rhodes, Ryan E.; Blanchard, Chris M.; Courneya, Kerry S.; Plotnikoff, Ronald C.
2009-01-01
Walking is the most common type of physical activity (PA) and the likely target of efforts to increase PA. No studies, however, have identified the belief-level correlates for walking using the theory of planned behavior. This study elicits salient beliefs about walking and evaluates beliefs that may be most important for walking-promotion…
A Novel Approach for Generalising Walking Gaits across Embodiments and Behaviours
Vijayakumar, Sethu
A Novel Approach for Generalising Walking Gaits across Embodiments and Behaviours Hsiu-Chin Lin1 of generalising walking gaits across different subjects and behaviours. Walking gaits are a result of complex. The problem is formalised using a walking phase model, and the nullspace learning method is used to generalise
Treadmill Adaptation and Verification of Self-Selected Walking Speed: A Protocol for Children
ERIC Educational Resources Information Center
Amorim, Paulo Roberto S.; Hills, Andrew; Byrne, Nuala
2009-01-01
Walking is a common activity of daily life and researchers have used the range 3-6 km.h[superscript -1] as reference for walking speeds habitually used for transportation. The term self-selected (i.e., individual or comfortable walking pace or speed) is commonly used in the literature and is identified as the most efficient walking speed, with…
SYSTEMS OF ONE-DIMENSIONAL RANDOM WALKS IN A COMMON RANDOM ENVIRONMENT
Peterson, Jonathon
SYSTEMS OF ONE-DIMENSIONAL RANDOM WALKS IN A COMMON RANDOM ENVIRONMENT JONATHON PETERSON Abstract. We consider a system of independent one-dimensional random walks in a common random environment under-dimensional random walks in a common random environment. We modify the standard notion of random walks in random
The Effects of a 12-Week Walking Program on Community-Dwelling Older Adults
ERIC Educational Resources Information Center
Cheng, Shun-Ping; Tsai, Tzu-I; Lii, Yun-Kung; Yu, Shu; Chou, Chen-Liang; Chen, I-Ju
2009-01-01
Walking is a popular and easily accessible form of physical activity. However, walking instruction for older adults is based on the evidence gathered from younger populations. This study evaluated walking conditions, strength, balance, and subjective health status after a 12-week walking-training program in community-dwelling adults greater than…
Vaulting mechanics successfully predict decrease in walk-run transition speed with incline.
Hubel, Tatjana Y; Usherwood, James R
2013-04-23
There is an ongoing debate about the reasons underlying gait transition in terrestrial locomotion. In bipedal locomotion, the 'compass gait', a reductionist model of inverted pendulum walking, predicts the boundaries of speed and step length within which walking is feasible. The stance of the compass gait is energetically optimal-at walking speeds-owing to the absence of leg compression/extension; completely stiff limbs perform no work during the vaulting phase. Here, we extend theoretical compass gait vaulting to include inclines, and find good agreement with previous observations of changes in walk-run transition speed (approx. 1% per 1% incline). We measured step length and frequency for humans walking either on the level or up a 9.8 per cent incline and report preferred walk-run, walk-compliant-walk and maximum walk-run transition speeds. While the measured 'preferred' walk-run transition speed lies consistently below the predicted maximum walking speeds, and 'actual' maximum walking speeds are clearly above the predicted values, the onset of compliant walking in level as well as incline walking occurs close to the predicted values. These findings support the view that normal human walking is constrained by the physics of vaulting, but preferred absolute walk-run transition speeds may be influenced by additional factors. PMID:23325739
Wilson Loops in string duals of Walking and Flavored Systems
Carlos Nunez; Maurizio Piai; Antonio Rago
2010-04-09
We consider the VEV of Wilson loop operators by studying the behavior of string probes in solutions of Type IIB string theory generated by Nc D5 branes wrapped on an 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.
Entanglement generation in spatially separated systems using quantum walk
C. M. Chandrashekar; Sandeep K. Goyal; Subhashish Banerjee
2012-06-22
We present a novel scheme to generate entanglement between two spatially separated systems. The scheme makes use of spatial entanglement generated by a single-particle quantum walk which is used to entangle two spatially separated, not necessarily correlated, systems. This scheme can be used to entangle any two systems which can interact with the spatial modes entangled during the quantum walk evolution. A notable feature is that we can control the quantum walk dynamics and its ability to localize leads to a substantial control and improvement in the entanglement output.
Quantization and asymptotic behaviour of ? quantum random walk on integers
NASA Astrophysics Data System (ADS)
Ellinas, Demosthenes; Smyrnakis, Ioannis
2006-06-01
Quantization and asymptotic behaviour of a variant of discrete random walk on integers are investigated. This variant, the ? walk, has the novel feature that it uses many identical quantum coins keeping at the same time characteristic quantum features like the quadratically faster than the classical spreading rate, and unexpected distribution cutoffs. A weak limit of the position probability distribution (pd) is obtained, and universal properties of this arch sine asymptotic distribution function are examined. Questions of driving the walk are investigated by means of a quantum optical interaction model that reveals robustness of quantum features of walker's asymptotic pd, against stimulated and spontaneous quantum noise on the coin system.
Decoherence in a one-dimensional quantum walk
Annabestani, Mostafa; Abolhassani, Mohamad Reza; Akhtarshenas, Seyed Javad
2010-03-15
In this article we study decoherence in the discrete-time quantum walk on the line. We generalize the method of decoherent coin quantum walk, introduced by Brun et al. [Phys. Rev. A 67, 32304 (2003)]. Our analytical expressions are applicable for all kinds of decoherence. As an example of the coin-position decoherence, we study the broken line quantum walk and compare our results with the numerical one. We also show that our analytical results reduce to the Brun formalism when only the coin is subjected to decoherence.
Perception, planning, and control for walking on rugged terrain
NASA Technical Reports Server (NTRS)
Simmons, Reid; Krotkov, Eric
1991-01-01
The CMU Planetary Rover project is developing a six-legged walking robot capable of autonomously navigating, exploring, and acquiring samples in rugged, unknown environments. To gain experience with the problems involved in walking on rugged terrain, a full-scale prototype leg was built and mounted on a carriage that rolls along overhead rails. Issues addressed in developing the software system to autonomously walk the leg through rugged terrain are described. In particular, the insights gained into perceiving and modeling rugged terrain, controlling the legged mechanism, interacting with the ground, choosing safe yet effective footfalls, and planning efficient leg moves through space are described.
Quantum Walk on the Line through Potential Barriers
Thomas G. Wong
2015-12-07
Quantum walks are well-known for their ballistic dispersion, traveling $\\Theta(t)$ away in $t$ steps, which is quadratically faster than a classical random walk's diffusive spreading. In physical implementations of the walk, however, the particle may need to tunnel through a potential barrier to hop, and a naive calculation suggests this could eliminate the ballistic transport. We show by explicit calculation, however, that such a loss does not occur. Rather, the $\\Theta(t)$ dispersion is retained, with only the coefficient changing, which additionally gives a way to detect and quantify the hopping errors in experiments.
Talaty, Mukul; Esquenazi, Alberto; Briceno, Jorge E
2013-06-01
The ReWalk(TM) powered exoskeleton assists thoracic level motor complete spinal cord injury patients who are paralyzed to walk again with an independent, functional, upright, reciprocating gait. We completed an evaluation of twelve such individuals with promising results. All subjects met basic criteria to be able to use the ReWalk(TM)--including items such as sufficient bone mineral density, leg passive range of motion, strength, body size and weight limits. All subjects received approximately the same number of training sessions. However there was a wide distribution in walking ability. Walking velocities ranged from under 0.1m/s to approximately 0.5m/s. This variability was not completely explained by injury level The remaining sources of that variability are not clear at present. This paper reports our preliminary analysis into how the walking kinematics differed across the subjects--as a first step to understand the possible contribution to the velocity range and determine if the subjects who did not walk as well could be taught to improve by mimicking the better walkers. PMID:24187286
Long, Leroy L.; Srinivasan, Manoj
2013-01-01
On a treadmill, humans switch from walking to running beyond a characteristic transition speed. Here, we study human choice between walking and running in a more ecological (non-treadmill) setting. We asked subjects to travel a given distance overground in a given allowed time duration. During this task, the subjects carried, and could look at, a stopwatch that counted down to zero. As expected, if the total time available were large, humans walk the whole distance. If the time available were small, humans mostly run. For an intermediate total time, humans often use a mixture of walking at a slow speed and running at a higher speed. With analytical and computational optimization, we show that using a 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
Record statistics of financial time series and geometric random walks
NASA Astrophysics Data System (ADS)
Sabir, Behlool; Santhanam, M. S.
2014-09-01
The study of record statistics of correlated series in physics, such as random walks, is gaining momentum, and several analytical results have been obtained in the past few years. In this work, we study the record statistics of correlated empirical data for which random walk models have relevance. We obtain results for the records statistics of select stock market data and the geometric random walk, primarily through simulations. We show that the distribution of the age of records is a power law with the exponent ? 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.
Robust Execution of Bipedal Walking Tasks From Biomechanical Principles
Hofmann, Andreas
2006-04-28
Effective use of robots in unstructured environments requires that they have sufficient autonomy and agility to execute task-level commands successfully. A challenging example of such a robot is a bipedal walking machine. ...
Robust execution of bipedal walking tasks from biomechanical principles
Hofmann, Andreas G. (Andreas Gunther)
2006-01-01
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. ...
61. View forward down hurricane deck toward salon clerestory, walking ...
61. View forward down hurricane deck toward salon clerestory, walking beam, stack, and wheelhouse. Second smaller stack is from donkey boiler on main deck. - Ferry TICONDEROGA, Route 7, Shelburne, Chittenden County, VT
9. Detail Showing top of Samson Post and Walking Beam ...
9. Detail Showing top of Samson Post and Walking Beam Pivot, Looking East - David Renfrew Oil Rig, East side of Connoquenessing Creek, 0.4 mile North of confluence with Thorn Creek, Renfrew, Butler County, PA
Minimal Walking Technicolor: Set Up for Collider Physics
R. Foadi; M. T. Frandsen; T. A. Ryttov; F. Sannino
2007-06-12
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.
A model of muscle-tendon function in human walking
Endo, Ken
In this paper, we study the mechanical behavior of leg muscles and tendons during human walking in order to motivate the design of economical robotic legs. We hypothesize that quasi-passive, series-elastic clutch units ...
Human walking model predicts joint mechanics, electromyography and mechanical economy
Endo, Ken
In this paper, we present an under-actuated model of human walking, comprising only a soleus muscle and flexion/extension monoarticular hip muscles. The remaining muscle groups of the human leg are modeled using quasi-passive, ...
4. Band Wheel and Walking Beam Mechanism, Including Remains of ...
4. Band Wheel and Walking Beam Mechanism, Including Remains of Frame Belt House, Looking Southeast - David Renfrew Oil Rig, East side of Connoquenessing Creek, 0.4 mile North of confluence with Thorn Creek, Renfrew, Butler County, PA
Online pose classification and walking speed estimation using handheld devices
Park, Jun-geun
We describe and evaluate two methods for device pose classification and walking speed estimation that generalize well to new users, compared to previous work. These machine learning based methods are designed for the general ...
72. View looking SE down pedestrian walking away from bridge ...
72. View looking SE down pedestrian walking away from bridge towards Brooklyn. Jet Lowe, photographer, 1982. - Brooklyn Bridge, Spanning East River between Park Row, Manhattan and Sands Street, Brooklyn, New York, New York County, NY
1. VIEW LOOKING SOUTH, SHOWING AFRAME OF WALKING BEAM ENGINE, ...
1. VIEW LOOKING SOUTH, SHOWING A-FRAME OF WALKING BEAM ENGINE, BOW END TO LEFT Edward Larrabee, photographer, November 1984 - Shooters Island, Ships Graveyard, Vessel No. 53, Newark Bay, Staten Island (subdivision), Richmond County, NY
Two-particle quantum walks: Entanglement and graph isomorphism testing
NASA Astrophysics Data System (ADS)
Berry, Scott D.; Wang, Jingbo B.
2011-04-01
We study discrete-time quantum walks on the line and on general undirected graphs with two interacting or noninteracting particles. We introduce two simple interaction schemes and show that they both lead to a diverse range of probability distributions that depend on the correlations and relative phases between the initial coin states of the two particles. We investigate the characteristics of these quantum walks and the time evolution of the entanglement between the two particles from both separable and entangled initial states. We also test the capability of two-particle discrete-time quantum walks to distinguish nonisomorphic graphs. For strongly regular graphs, we show that noninteracting discrete-time quantum walks can distinguish some but not all nonisomorphic graphs with the same family parameters. By incorporating an interaction between the two particles, all nonisomorphic strongly regular graphs tested are successfully distinguished.
Measurement of pressure walking in footwear used in leprosy.
Birke, J A; Foto, J G; Deepak, S; Watson, J
1994-09-01
Pressure measurements were made on 10 leprosy patients while walking barefoot and while using 6 sample shoes. The sample shoes, which represented footwear currently used worldwide in leprosy programmes, included: 1, a USA extradepth shoe without insole; 2, a USA extradepth shoe with insole; 3, a Chinese tennis shoe; 4, a Mozambique sandal; 5, a Bombay sandal; 6, a Bombay sandal with rigid sole; and 7, the patients' prescribed footwear. Peak pressure was significantly lower while walking in all footwear, except with the extradepth shoe without an insole, when compared to barefoot walking. Peak pressure was significantly lower walking in the Bombay sandals, the Chinese tennis shoe, the extradepth shoe with an insert and the patients' prescribed shoe when compared to the extradepth shoe without an insert. Regression analysis showed a significant inverse relationship between pressure and insole thickness (P < 0.001, R2 = 0.17). PMID:8942157
Localization in quantum walks on a honeycomb network
NASA Astrophysics Data System (ADS)
Lyu, Changyuan; Yu, Luyan; Wu, Shengjun
2015-11-01
We systematically study the localization effect in discrete-time quantum walks on a honeycomb network and establish the mathematical framework. We focus on the Grover walk first and rigorously derive the limit form of the walker's state, showing it has a certain probability to be localized at the starting position. The relationship between localization and the initial coin state is concisely represented by a linear map. We also define and calculate the average probability of localization by generating random initial states. Further, coin operators varying with positions are considered and the sufficient condition for localization is discussed. We also similarly analyze another four-state Grover walk. Theoretical predictions are all in accord with numerical simulation results. Finally, our results are compared with previous works to demonstrate the unusual trapping effect of quantum walks on a honeycomb network, as well as the advantages of our method.
A scaling law for random walks on networks.
Perkins, Theodore J; Foxall, Eric; Glass, Leon; Edwards, Roderick
2014-01-01
The dynamics of many natural and artificial systems are well described as random walks on a network: the stochastic behaviour of molecules, traffic patterns on the internet, fluctuations in stock prices and so on. The vast literature on random walks provides many tools for computing properties such as steady-state probabilities or expected hitting times. Previously, however, there has been no general theory describing the distribution of possible paths followed by a random walk. Here, we show that for any random walk on a finite network, there are precisely three mutually exclusive possibilities for the form of the path distribution: finite, stretched exponential and power law. The form of the distribution depends only on the structure of the network, while the stepping probabilities control the parameters of the distribution. We use our theory to explain path distributions in domains such as sports, music, nonlinear dynamics and stochastic chemical kinetics. PMID:25311870
A plasmonic nanorod that walks on DNA origami
NASA Astrophysics Data System (ADS)
Zhou, Chao; Duan, Xiaoyang; Liu, Na
2015-08-01
In nano-optics, a formidable challenge remains in precise transport of a single optical nano-object along a programmed and routed path toward a predefined destination. Molecular motors in living cells that can walk directionally along microtubules have been the inspiration for realizing artificial molecular walkers. Here we demonstrate an active plasmonic system, in which a plasmonic nanorod can execute directional, progressive and reverse nanoscale walking on two or three-dimensional DNA origami. Such a walker comprises an anisotropic gold nanorod as its `body' and discrete DNA strands as its `feet'. Specifically, our walker carries optical information and can in situ optically report its own walking directions and consecutive steps at nanometer accuracy, through dynamic coupling to a plasmonic stator immobilized along its walking track. Our concept will enable a variety of smart nanophotonic platforms for studying dynamic light-matter interaction, which requires controlled motion at the nanoscale well below the optical diffraction limit.
Record statistics of financial time series and geometric random walks.
Sabir, Behlool; Santhanam, M S
2014-09-01
The study of record statistics of correlated series in physics, such as random walks, is gaining momentum, and several analytical results have been obtained in the past few years. In this work, we study the record statistics of correlated empirical data for which random walk models have relevance. We obtain results for the records statistics of select stock market data and the geometric random walk, primarily through simulations. We show that the distribution of the age of records is a power law with the exponent ? 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
Powered Ankle–Foot Prosthesis Improves Walking Metabolic Economy
Au, Samuel K.
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 ...
On the Mechanics of Functional Asymmetry in Bipedal Walking
Dhaher, Yasin Y.; Degani, Amir; Lynch, Kevin M.
2014-01-01
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
A scaling law for random walks on networks
NASA Astrophysics Data System (ADS)
Perkins, Theodore J.; Foxall, Eric; Glass, Leon; Edwards, Roderick
2014-10-01
The dynamics of many natural and artificial systems are well described as random walks on a network: the stochastic behaviour of molecules, traffic patterns on the internet, fluctuations in stock prices and so on. The vast literature on random walks provides many tools for computing properties such as steady-state probabilities or expected hitting times. Previously, however, there has been no general theory describing the distribution of possible paths followed by a random walk. Here, we show that for any random walk on a finite network, there are precisely three mutually exclusive possibilities for the form of the path distribution: finite, stretched exponential and power law. The form of the distribution depends only on the structure of the network, while the stepping probabilities control the parameters of the distribution. We use our theory to explain path distributions in domains such as sports, music, nonlinear dynamics and stochastic chemical kinetics.
A plasmonic nanorod that walks on DNA origami
Zhou, Chao; Duan, Xiaoyang; Liu, Na
2015-01-01
In nano-optics, a formidable challenge remains in precise transport of a single optical nano-object along a programmed and routed path toward a predefined destination. Molecular motors in living cells that can walk directionally along microtubules have been the inspiration for realizing artificial molecular walkers. Here we demonstrate an active plasmonic system, in which a plasmonic nanorod can execute directional, progressive and reverse nanoscale walking on two or three-dimensional DNA origami. Such a walker comprises an anisotropic gold nanorod as its ‘body' and discrete DNA strands as its ‘feet'. Specifically, our walker carries optical information and can in situ optically report its own walking directions and consecutive steps at nanometer accuracy, through dynamic coupling to a plasmonic stator immobilized along its walking track. Our concept will enable a variety of smart nanophotonic platforms for studying dynamic light–matter interaction, which requires controlled motion at the nanoscale well below the optical diffraction limit. PMID:26303016
Kinematic study of human ankle control during walking
Zimmerman, Julia C
2009-01-01
In order to determine the extent to which ankle motion is voluntarily controlled during walking, angular velocity measurements at the ankle were taken in two cases. In the first case, subjects were seated and instructed ...
Evidence of Lvy walk foraging patterns in human huntergatherers
Pontzer, Herman
Evidence of Lévy walk foraging patterns in human huntergatherers David A. Raichlena,1 , Brian M patterns in human foraging. Here, we show that human huntergatherers, the Hadza of northern Tanzania/'hoansi huntergather
Kinematic parameters of sheep walking on a treadmill.
Valentin, Stephanie; Essigbeck, Annika; Wolfram, Ines; Licka, Theresia
2014-12-01
Ovine locomotion studies are rare, despite their relevance for medical research. The aim of this preliminary study was to investigate habituation and temporospatial parameters during treadmill walking of seven Austrian Mountain sheep. Sheep were naïve to treadmill exercise. During five treadmill sessions, movement cycle duration (MCD), vertical trunk movement (VTM), stride height (SH), stride length (SL), and percentage of movement cycle at stance (%St) were assessed. Two sheep were excluded from the study because they would not walk on the treadmill. From the end measurement session, MCD (0.95?s) and %St (62%) were similar to reported kinetics of sheep walking over ground, although stride length (1.05?m) was longer in this study. These findings suggest that sheep may require more than five sessions to become habituated to treadmill walking. PMID:25457259
Kinematic parameters of sheep walking on a treadmill
Valentin, Stephanie; Essigbeck, Annika; Wolfram, Ines; Licka, Theresia
2014-01-01
Ovine locomotion studies are rare, despite their relevance for medical research. The aim of this preliminary study was to investigate habituation and temporospatial parameters during treadmill walking of seven Austrian Mountain sheep. Sheep were 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
Synthesizing Human-Like Walking in Constrained Environments
North Carolina at Chapel Hill, University of
and Liangjun Zhang and Dinesh Manocha to model different motions such as navigation, sitting, walking, running constraints, we also need to ensure that the resulting trajectory satisfies the posture and dynamic
FRACTAL DIMENSION RESULTS FOR CONTINUOUS TIME RANDOM WALKS
Meerschaert, Mark M.; Nane, Erkan; Xiao, Yimin
2013-01-01
Continuous time random walks impose random waiting times between particle jumps. This paper computes the fractal dimensions of their process limits, which represent particle traces in anomalous diffusion. PMID:23482421
BCI Controlled Walking Simulator For a BCI Driven FES Device
Nenadic, Zoran
to spinal cord injury (SCI), a BCI controlled walking simulator was developed SAmulaAon; Spinal Cord Injury; Gait BACKGROUND Spinal cord injury (SCI) paAents are o and manipulate their environment by "thought," thereby bypassing a damaged spinal
Tunneling effects in a one-dimensional quantum walk
Mostafa Annabestani; Seyed Javad Akhtarshenas; Mohamad Reza Abolhassani
2010-04-25
In this article we investigate the effects of shifting position decoherence, arisen from the tunneling effect in the experimental realization of the quantum walk, on the one-dimensional discreet time quantum walk. We show that in the regime of this type of noise the quantum behavior of the walker does not fade, in contrary to the coin decoherence for which the walker undergos the quantum-to-classical transition even for weak noise. Particularly, we show that the quadratic dependency of the variance on the time and also the coin-position entanglement, i.e. two important quantum aspects of the coherent quantum walk, are preserved in the presence of tunneling decoherence. Furthermore, we present an explicit expression for the probability distribution of decoherent one-dimensional quantum walk in terms of the corresponding coherent probabilities, and show that this type of decoherence smooths the probability distribution.
Group Velocity of Discrete-Time Quantum Walks
Achim Kempf; Renato Portugal
2009-01-27
We show that certain types of quantum walks can be modeled as waves that propagate in a medium with phase and group velocities that are explicitly calculable. Since the group and phase velocities indicate how fast wave packets can propagate causally, we propose the use of these wave velocities in a new definition for the hitting time of quantum walks. The new definition of hitting time has the advantage that it requires neither the specification of a walker's initial condition nor of an arrival probability threshold. We give full details for the case of quantum walks on the Cayley graphs of Abelian groups. This includes the special cases of quantum walks on the line and on hypercubes.
The hydrodynamics of water-walking insects and spiders
Hu, David L., 1979-
2006-01-01
We present a combined experimental and theoretical investigation of the numerous hydrodynamic propulsion mechanisms employed by water-walking arthropods (insects and spiders). In our experimental study, high speed ...
a Novel Sideway Stability Control Method for Bipedal Walking Robot
NASA Astrophysics Data System (ADS)
Jo, H. Siswoyo; Mir-Nasiri, N.
2011-06-01
This paper presents a novel sensing and balancing method for bipedal walking robot. The proposed method involves the design of semi-rigid ankle joint to facilitate the responsive and accurate measurement of the sideway (sagittal) instability of the walking robot. The use of double balancing mass and the developed control algorithms provide a constant sideway stability of the robot while it walks in forward direction. The smooth legs trajectory planning then can be implemented successfully regardless of the robot sideway stability condition. The developed method is able to decouple the walking algorithms from the robot stability issues. Furthermore, the use of two different masses for the balancing helps to improve response time and efficiency of the balancing system. In this paper, the proposed method is tested on the simplified model of a robot balancing on its single leg and the feasibility of the method is confirmed by the simulation results obtained with MATLAB Simulink tools.
Inequalities for the Number of Walks in Graphs Raymond Hemmecke
Deussen, Oliver
Inequalities for the Number of Walks in Graphs Raymond Hemmecke Sven Kosub Ernst W. Mayr Hanjo T.Kosub@uni-konstanz.de Institut f¨ur Informatik, Technische Universit¨at M¨unchen, D- 85748 Garching, Germany, {mayr
Base Station Walk-Back - Duration: 2 minutes, 10 seconds.
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...
10. CLIFTON HILL, LOOKING NORTHWEST ACROSS STREAM FROM HAZEL WALK ...
10. CLIFTON HILL, LOOKING NORTHWEST ACROSS STREAM FROM HAZEL WALK Photocopy of photograph, 1930s National Park Service, National Capital Region files - Dumbarton Oaks Park, Thirty-second & R Streets Northwest, Washington, District of Columbia, DC
9. CLIFTON HILL, LOOKING NORTHEAST ACROSS STREAM FROM HAZEL WALK ...
9. CLIFTON HILL, LOOKING NORTHEAST ACROSS STREAM FROM HAZEL WALK Photocopy of photograph, 1930s National Park Service, National Capital Region files - Dumbarton Oaks Park, Thirty-second & R Streets Northwest, Washington, District of Columbia, DC
For a Better Calorie Burn, Adjust Your Speed While Walking
... medlineplus/news/fullstory_155127.html For a Better Calorie Burn, Adjust Your Speed While Walking Stopping and ... This caloric cost is often not included in calorie-burning estimations, Srinivasan's group said. Study lead author ...
Sleep-Walking a Rarest Side Effect of Zolpidem
Singh, Harmanjit; Thangaraju, Pugazhenthan; Natt, Navreet Kaur
2015-01-01
A 46-years-old male, with past history of road traffic accident and with no current/past history of substance abuse and no family history of sleep-walking, took zolpidem 10 mg without any prescription and after few days, the patient's son noticed the patient waking up in the middle of night and walking into their room with a staring expression and some incoherent speech. The patient had no memory of this event in the morning. This sleep-walking episode was attributed to zolpidem, as no medication change was made besides new start of zolpidem and the patient had no history of such episodes in the past. Zolpidem treatment was stopped, and since then, no further complaints of sleep-walking were reported. PMID:25722525
The Einstein Relation for RandomWalks on Graphs
NASA Astrophysics Data System (ADS)
Telcs, András
2006-05-01
This paper investigates the Einstein relation; the connection between the volume growth, the resistance growth and the expected time a random walk needs to leave a ball on a weighted graph. The Einstein relation is proved under different set of conditions. In the simplest case it is shown under the volume doubling and time comparison principles. This and the other set of conditions provide the basic framework for the study of (sub-) diffusive behavior of the random walks on weighted graphs.
The Einstein Relation for Random Walks on Graphs
NASA Astrophysics Data System (ADS)
Telcs, András
2006-02-01
This paper investigates the Einstein relation; the connection between the volume growth, the resistance growth and the expected time a random walk needs to leave a ball on a weighted graph. The Einstein relation is proved under different set of conditions. In the simplest case it is shown under the volume doubling and time comparison principles. This and the other set of conditions provide the basic framework for the study of (sub-) diffusive behavior of the random walks on weighted graphs.
Ising model observables and non-backtracking walks
Helmuth, Tyler
2014-08-15
This paper presents an alternative proof of the connection between the partition function of the Ising model on a finite graph G and the set of non-backtracking walks on G. The techniques used also give formulas for spin-spin correlation functions in terms of non-backtracking walks. The main tools used are Viennot's theory of heaps of pieces and turning numbers on surfaces.
Changes in walking and running in patients with hip dysplasia
2013-01-01
Background and purpose Earlier studies have suggested that the hip extension angle and the hip flexor moment in walking are affected by hip dysplasia, but to our knowledge there have been no reports on running or evaluations of self-reported health. We evaluated differences in walking, running, and self-reported health between young adults with symptomatic hip dysplasia and healthy controls. Patients and methods Walking and running in 32 patients with hip dysplasia, mean 34 (18–53) years old, was compared with walking and running in 32 controls, mean 33 (18–54) years old. Joint kinematics and kinetics—quantified by the peak hip extension angle and the peak net joint moment of hip flexion during walking and running—were recorded using a motion-capture system, and health was evaluated using the Copenhagen Hip and Groin Outcome Score (HAGOS). Results The peak hip extension angle during walking was less in the patients than in the controls (–10.4 (SD 4.8) degrees vs. –13.2 (SD 4.5) degrees; p = 0.02). Similarly, the peak net joint moment of hip flexion during walking was lower in the patients than in the controls (0.57 (SD 0.13) N*m/kg vs. 0.70 (SD 0.22) N*m/kg; p = 0.008). In all dimensions of HAGOS, the patients scored lower than the controls. Furthermore, the hip extension angle and the net joint moment of hip flexion correlated with the HAGOS subscales pain and physical function in sport and recreation. Interpretation Patients with symptomatic hip dysplasia do modify walking and running, and we therefore suggest that the impairment found in this study should play an important role in the evaluation of later operative and training interventions. PMID:23594221
Central Limit Theorem for Branching Random Walks in Random Environment
Nobuo Yoshida
2007-12-05
We consider branching random walks in $d$-dimensional integer lattice with time-space i.i.d. offspring distributions. When $d \\ge 3$ and the fluctuation of the environment is well moderated by the random walk, we prove a central limit theorem for the density of the population, together with upper bounds for the density of the most populated site and the replica overlap. We also discuss the phase transition of this model in connection with directed polymers in random environment.
Nonlinear time series analysis of normal and pathological human walking
NASA Astrophysics Data System (ADS)
Dingwell, Jonathan B.; Cusumano, Joseph P.
2000-12-01
Characterizing locomotor dynamics is essential for understanding the neuromuscular control of locomotion. In particular, quantifying dynamic stability during walking is important for assessing people who have a greater risk of falling. However, traditional biomechanical methods of defining stability have not quantified the resistance of the neuromuscular system to perturbations, suggesting that more precise definitions are required. For the present study, average maximum finite-time Lyapunov exponents were estimated to quantify the local dynamic stability of human walking kinematics. Local scaling exponents, defined as the local slopes of the correlation sum curves, were also calculated to quantify the local scaling structure of each embedded time series. Comparisons were made between overground and motorized treadmill walking in young healthy subjects and between diabetic neuropathic (NP) patients and healthy controls (CO) during overground walking. A modification of the method of surrogate data was developed to examine the stochastic nature of the fluctuations overlying the nominally periodic patterns in these data sets. Results demonstrated that having subjects walk on a motorized treadmill artificially stabilized their natural locomotor kinematics by small but statistically significant amounts. Furthermore, a paradox previously present in the biomechanical literature that resulted from mistakenly equating variability with dynamic stability was resolved. By slowing their self-selected walking speeds, NP patients adopted more locally stable gait patterns, even though they simultaneously exhibited greater kinematic variability than CO subjects. Additionally, the loss of peripheral sensation in NP patients was associated with statistically significant differences in the local scaling structure of their walking kinematics at those length scales where it was anticipated that sensory feedback would play the greatest role. Lastly, stride-to-stride fluctuations in the walking patterns of all three subject groups were clearly distinguishable from linearly autocorrelated Gaussian noise. As a collateral benefit of the methodological approach taken in this study, some of the first steps at characterizing the underlying structure of human locomotor dynamics have been taken. Implications for understanding the neuromuscular control of locomotion are discussed.
Straight walking and turning on a slippery surface.
Gruhn, Matthias; Zehl, Lyuba; Büschges, Ansgar
2009-01-01
In stick insects, walking is the result of the co-action of different pattern generators for the single legs and coordinating inter-leg influences. We have used a slippery surface setup to understand the role the local neuronal processing in the thoracic ganglia plays in the ability of the animal to show turning movements. To achieve this, we removed the influence of mechanical coupling through the ground by using the slippery surface and removed sensory input by the successive amputation of neighboring legs. We analyzed the walking pattern of the front, middle and hind legs of tethered animals mounted above the surface and compared the kinematics of the straight walking legs with those of the curve walking inside and outside legs. The walking pattern was monitored both electrically through tarsal contact measurement and optically by using synchronized high-speed video. The vectors of leg movement are presented for the intact and a reduced preparation. Animals showed the ability to walk in a coordinated fashion on the slippery surface. Upon change from straight to curve walking, the stride length for the inside legs shortens and the vector of movement of the inner legs changes to pull the animal into the curve, while the outer legs act to pull and push it into the turn. In the reduced two-leg and in the single-leg preparation the behavior of the legs remained largely unchanged in the behavioral contexts of straight walking or turning with only small changes in the extreme positions. This suggests that the single stepping legs perform given motor programs on the slippery surface in a fashion that is highly independent not only of mechanical coupling between but also of the presence of the other legs. PMID:19112138
The melting phenomenon in random-walk model of DNA
Hayrapetyan, G. N.; Mamasakhlisov, E. Sh.; Papoyan, Vl. V.; Poghosyan, S. S.
2012-10-15
The melting phenomenon in a double-stranded homopolypeptide is considered. The relative distance between the corresponding monomers of two polymer chains is modeled by the two-dimensional random walk on the square lattice. Returns of the random walk to the origin describe the formation of hydrogen bonds between complementary units. To take into account the two competing interactions of monomers inside the chains, we obtain a completely denatured state at finite temperature T{sub c}.
The role of series ankle elasticity in bipedal walking
Zelik, Karl E.; Huang, Tzu-Wei P.; Adamczyk, Peter G.; Kuo, Arthur D.
2014-01-01
The elastic stretch-shortening cycle of the Achilles tendon during walking can reduce the active work demands on the plantarflexor muscles in series. However, this does not explain why or when this ankle work, whether by muscle or tendon, needs to be performed during gait. We therefore employ a simple bipedal walking model to investigate how ankle work and series elasticity impact economical locomotion. Our model shows that ankle elasticity can use passive dynamics to aid push-off late in single support, redirecting the body's center-of-mass (COM) motion upward. An appropriately timed, elastic push-off helps to reduce dissipative collision losses at contralateral heelstrike, and therefore the positive work needed to offset those losses and power steady walking. Thus, the model demonstrates how elastic ankle work can reduce the total energetic demands of walking, including work required from more proximal knee and hip muscles. We found that the key requirement for using ankle elasticity to achieve economical gait is the proper ratio of ankle stiffness to foot length. Optimal combination of these parameters ensures proper timing of elastic energy release prior to contralateral heelstrike, and sufficient energy storage to redirect the COM velocity. In fact, there exist parameter combinations that theoretically yield collision-free walking, thus requiring zero active work, albeit with relatively high ankle torques. Ankle elasticity also allows the hip to power economical walking by contributing indirectly to push-off. Whether walking is powered by the ankle or hip, ankle elasticity may aid walking economy by reducing collision losses. PMID:24365635
Predicting human walking gaits with a simple planar model.
Martin, Anne E; Schmiedeler, James P
2014-04-11
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
Introduction of New Motion Measurement Equipment into Virtual Walk System
NASA Astrophysics Data System (ADS)
Furukawa, Tatsuya; Itoh, Hideaki; Hori, Toshiyuki; Fukumoto, Hisao; Wakuya, Hiroshi; Ohchi, Masashi
The “Virtual Walk System” has been developed to support rehabilitation therapy in homes. In the system, a user has been able to perform walking-like exercise on a fitness machine called a stepper. In front of the user, a projected image of a vast virtual reality space is generated by 3-dimensional computer graphics (3DCG). The user's movement is measured and the projected image changes just like the user is walking in the virtual space. Viewing the changing image, the user can enjoy the exercise. In this study, we have decomposed the virtual walk system into two modules (the measurement and control module operated by a microcomputer board and the 3DCG module operated by a personal computer) to facilitate rapid development. Then we have introduced two kinds of new equipment, i.e., a bicycle for cycling exercise and a treadmill for walking exercise. We have also developed a treadmill control system by which a user can easily change the walking speed during exercise.
Integration of Human Walking Gyroscopic Data Using Empirical Mode Decomposition
Bonnet, Vincent; Ramdani, Sofiane; Azevedo-Coste, Christine; Fraisse, Philippe; Mazzà, Claudia; Cappozzo, Aurelio
2014-01-01
The present study was aimed at evaluating the Empirical Mode Decomposition (EMD) method to estimate the 3D orientation of the lower trunk during walking using the angular velocity signals generated by a wearable inertial measurement unit (IMU) and notably flawed by drift. The IMU was mounted on the lower trunk (L4-L5) with its active axes aligned with the relevant anatomical axes. The proposed method performs an offline analysis, but has the advantage of not requiring any parameter tuning. The method was validated in two groups of 15 subjects, one during overground walking, with 180° turns, and the other during treadmill walking, both for steady-state and transient speeds, using stereophotogrammetric data. Comparative analysis of the results showed that the IMU/EMD method is able to successfully detrend the integrated angular velocities and estimate lateral bending, flexion-extension as well as axial rotations of the lower trunk during walking with RMS errors of 1 deg for straight walking and lower than 2.5 deg for walking with turns. PMID:24379044
Trunk muscle activation patterns during walking at different speeds.
Anders, Christoph; Wagner, Heiko; Puta, Christian; Grassme, Roland; Petrovitch, Alexander; Scholle, Hans-Christoph
2007-04-01
Investigations of trunk muscle activation during gait are rare in the literature. As yet, the small body of literature on trunk muscle activation during gait does not include any systematic study on the influence of walking speed. Therefore, the aim of this study was to analyze trunk muscle activation patterns at different walking speeds. Fifteen healthy men were investigated during walking on a treadmill at speeds of 2, 3, 4, 5 and 6 km/h. Five trunk muscles were investigated using surface EMG (SEMG). Data were time normalized according to stride time and grand averaged SEMG curves were calculated. From these data stride characteristics were extracted: mean SEMG amplitude, minimum SEMG level and the variation coefficient (VC) over the stride period. With increasing walking speed, muscle activation patterns remained similar in terms of phase dependent activation during stride, but mean amplitudes increased generally. Phasic activation, indicated by VC, increased also, but remained almost unchanged for the back muscles (lumbar multifidus and erector spinae) between 4 and 6 km/h. During stride, minimum amplitude reached a minimum at 4 km/h for the back muscles, but for internal oblique muscle it decreased continuously from 2 to 6 km/h. Cumulative sidewise activation of all investigated muscles reached maximum amplitudes during the contralateral heel strike and propulsion phases. The observed changes argue for a speed dependent modulation of activation of trunk muscles within the investigated range of walking speeds prior to strictly maintaining certain activation characteristics for all walking speeds. PMID:16517182
Stance and swing phase costs in human walking
Umberger, Brian R.
2010-01-01
Leg swing in human walking has historically been viewed as a passive motion with little metabolic cost. Recent estimates of leg swing costs are equivocal, covering a range from 10 to 33 per cent of the net cost of walking. There has also been a debate as to whether the periods of double-limb support during the stance phase dominate the cost of walking. Part of this uncertainty is because of our inability to measure metabolic energy consumption in individual muscles during locomotion. Therefore, the purpose of this study was to investigate the metabolic cost of walking using a modelling approach that allowed instantaneous energy consumption rates in individual muscles to be estimated over the full gait cycle. At a typical walking speed and stride rate, leg swing represented 29 per cent of the total muscular cost. During the stance phase, the double-limb and single-limb support periods accounted for 27 and 44 per cent of the total cost, respectively. Performing step-to-step transitions, which encompasses more than just the double-support periods, represented 37 per cent of the total cost of walking. Increasing stride rate at a constant speed led to greater double-limb support costs, lower swing phase costs and no change in single-limb support costs. Together, these results provide unique insight as to how metabolic energy is expended over the human gait cycle. PMID:20356877
Current-reinforced random walks for constructing transport networks
Ma, Qi; Johansson, Anders; Tero, Atsushi; Nakagaki, Toshiyuki; Sumpter, David J. T.
2013-01-01
Biological systems that build transport networks, such as trail-laying ants and the slime mould Physarum, can be described in terms of reinforced random walks. In a reinforced random walk, the route taken by ‘walking’ particles depends on the previous routes of other particles. Here, we present a novel form of random walk in which the flow of particles provides this reinforcement. Starting from an analogy between electrical networks and random walks, we show how to include current reinforcement. We demonstrate that current-reinforcement results in particles converging on the optimal solution of shortest path transport problems, and avoids the self-reinforcing loops seen in standard density-based reinforcement models. We further develop a variant of the model that is biologically realistic, in the sense that the particles can be identified as ants and their measured density corresponds to those observed in maze-solving experiments on Argentine ants. For network formation, we identify the importance of nonlinear current reinforcement in producing networks that optimize both network maintenance and travel times. Other than ant trail formation, these random walks are also closely related to other biological systems, such as blood vessels and neuronal networks, which involve the transport of materials or information. We argue that current reinforcement is likely to be a common mechanism in a range of systems where network construction is observed. PMID:23269849
Intense Walking Exercise Affects Serum IGF-1 and IGFBP3
Kim, TaeHo; Chang, Jae Seung; Kim, Hanul; Lee, Kwang Ho; Kong, In Deok
2015-01-01
Background Insulin-like growth factor (IGF-1) is associated with chronic diseases such as diabetes, cardiovascular disease, and hypertension, as well as muscle dysfunction. Previous studies of exercise interventions yield controversial results regarding plasma IGF-1, IGFBP3, and IGF-1/IGFBP3 ratio. In this study, we examined whether 100 km walking exercise affects serum levels of IGF-1 and IGFBP3 and IGF-1/IGFBP3 ratio. We also investigated several metabolic-related blood parameters before and after walking. Methods Participants were 14 healthy middle aged men (41.0 ± 6.78 years of age). We assessed body composition and measured metabolic-related blood indicators, such as such as lipid profiles, glucose, renal and hepatic metabolic bio-markers before and after a 100 km walking race. Blood samples from all participants were taken before and immediately after the walkathon. We also analyzed serum levels of IGF-1 and IGFBP3, and calculated the IGF-1/IGFBP3 ratio. Results After participants completed a 100 km walking race, some of their metabolic profiles were markedly changed. Serum levels of IGF-1 and IGFBP3 were significantly decreased, and therefore the IGF-1/IGFBP3 ratio also decreased before and after 100 km of walking. Conclusion Our results indicate that intense walking exercise affects serum levels of IGF-1 and IGFBP3 as well as metabolic bio-markers including high density cholesterol, glucose and triglycerides. PMID:26528426
Development of walking pattern evaluation system for hypogravity simulation.
Leães, R; Cambraia, R; Bacim, F; Dalmarco, G; Calder, A; De Azevedo, D F G; Pinho, M; Russomano, T
2006-01-01
This study aimed to develop a Walking Pattern Evaluation System during Hypogravity Simulation (SAMSH), which included the adaptation of a body suspension device, the instrumentation of a treadmill and the development of a virtual environment. SAMSH was developed using one subject. Kinematic analyses were performed whilst one individual was walking on the treadmill during body weight reduction simulating the gravitational forces of the Moon (reduction of 60%) and Mars (reduction of 30%) with and without virtual reality glasses (Head Mounted Display, HMD). The walking pattern was evaluated by means of knee and ankle electrogoniometers, foot switches placed on the front and back part of the plantar region, and five video cameras. Results showed that the body weight reduction during Moon simulation alter the walking pattern, including the increase in step time, contact time, step length and aerial time, and the decrease of walking cadence time (steps per minute). The findings of this study also suggested that hypogravity simulation reduces walking effort. The utilization of the HMD allowed the evaluation of the head position three-dimensionally during hypogravity simulation. The virtual environment reduced postural balance, due to the absence of visual input, which was evidenced by a protective extension reaction. PMID:17947187
Human Body Detection that Uses Electric Field by Walking
NASA Astrophysics Data System (ADS)
Takiguchi, Kiyoaki; Wada, Takayuki; Toyama, Shigeki
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 by walking, thus forming an electrical field around the human body. It was considered from walking waveforms in which human walking was reflected that a human body could be detected more advantageously. The measuring method is not affected by vibrations, etc. In addition, detection is possible with a simple electrode, which is advantageous in terms of cost. In this study, electrification on the human body in which components of actions of both feet are superimposed will be measured at a remote place, under an assumed living environment, and by using an algorithm that remotely detects walking characteristics based on the waveforms in which movements of both feet are reflected. Walking of 10 subjects including infants was actually measured, and a system, which is capable of detecting the number of steps at an accuracy of approximately 99.4% was shown.
Federal Register 2010, 2011, 2012, 2013, 2014
2010-04-05
...The U.S. Department of Energy (DOE) will hold a public meeting to discuss and receive comments on: The equipment classes that DOE plans to analyze for establishing energy conservation standards for walk-in coolers and walk-in freezers; the analytical framework, models, and tools that DOE is using to evaluate standards for this equipment; the results of preliminary analyses performed by DOE for......
Reconstructing the behavior of walking fruit flies
NASA Astrophysics Data System (ADS)
Berman, Gordon; Bialek, William; Shaevitz, Joshua
2010-03-01
Over the past century, the fruit fly Drosophila melanogaster has arisen as almost a lingua franca in the study of animal behavior, having been utilized to study questions in fields as diverse as sleep deprivation, aging, and drug abuse, amongst many others. Accordingly, much is known about what can be done to manipulate these organisms genetically, behaviorally, and physiologically. Most of the behavioral work on this system to this point has been experiments where the flies in question have been given a choice between some discrete set of pre-defined behaviors. Our aim, however, is simply to spend some time with a cadre of flies, using techniques from nonlinear dynamics, statistical physics, and machine learning in an attempt to reconstruct and gain understanding into their behavior. More specifically, we use a multi-camera set-up combined with a motion tracking stage in order to obtain long time-series of walking fruit flies moving about a glass plate. This experimental system serves as a test-bed for analytical, statistical, and computational techniques for studying animal behavior. In particular, we attempt to reconstruct the natural modes of behavior for a fruit fly through a data-driven approach in a manner inspired by recent work in C. elegans and cockroaches.
Walking Technipions in a Holographic Model
Masafumi Kurachi; Shinya Matsuzaki; Koichi Yamawaki
2014-10-22
We calculate masses of the technipions in the walking technicolor model with the anomalous dimension gamma_m =1, based on a holographic model which has a naturally light technidilaton phi as a composite Higgs with mass m_phi simeq 125 GeV. The one-family model (with 4 weak-doublets) is taken as a concrete example in such a framework, with the inputs being F_pi=v/2 simeq 123 GeV and m_phi simeq 125 GeV as well as gamma_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 sector connected by the extended-technicolor-type interactions, in sharp contrast to the conventional S parameter constraint from the precision electroweak measurements.
Infrared dynamics of minimal walking technicolor
Del Debbio, Luigi; Lucini, Biagio; Patella, Agostino; Pica, Claudio; Rago, Antonio
2010-07-01
We study the gauge sector of minimal walking technicolor, which is an SU(2) gauge theory with n{sub f}=2 flavors of Wilson fermions in the adjoint representation. Numerical simulations are performed on lattices N{sub t}xN{sub s}{sup 3}, with N{sub s} ranging from 8 to 16 and N{sub t}=2N{sub s}, at fixed {beta}=2.25, and varying the fermion bare mass m{sub 0}, so that our numerical results cover the full range of fermion masses from the quenched region to the chiral limit. We present results for the string tension and the glueball spectrum. A comparison of mesonic and gluonic observables leads to the conclusion that the infrared dynamics is given by an SU(2) pure Yang-Mills theory with a typical energy scale for the spectrum sliding to zero with the fermion mass. The typical mesonic mass scale is proportional to and much larger than this gluonic scale. Our findings are compatible with a scenario in which the massless theory is conformal in the infrared. An analysis of the scaling of the string tension with the fermion mass toward the massless limit allows us to extract the chiral condensate anomalous dimension {gamma}{sub *}, which is found to be {gamma}{sub *}=0.22{+-}0.06.
Holographic Walking Technicolor from D-branes
Lilia Anguelova; Peter Suranyi; L. C. Rohana Wijewardhana
2011-05-20
We investigate a model of dynamical electroweak symmetry breaking via a dual gravitational description. The gravity dual is obtained by embedding a D7 - anti-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.
Discovering walking technirho mesons at the LHC
Masafumi Kurachi; Shinya Matsuzaki; Koichi Yamawaki
2014-09-22
We formulate a scale-invariant hidden local symmetry (HLS) as a low-energy effective theory of walking technicolor (WTC) which includes the technidilaton, technipions, and technirho mesons as the low-lying spectra. As a benchmark for LHC phenomenology, we in particular focus on the one-family model of WTC having eight technifermion flavors, which can be, at energy scales relevant to the reach of the LHC, described by the scale-invariant HLS based on the manifold $[SU(8)_L \\times SU(8)_R]_{\\rm global} \\times SU(8)_{\\rm local}/SU(8)_V$, where $SU(8)_{\\rm local}$ is the HLS and the global $SU(8)_L \\times SU(8)_R$ symmetry is partially gauged by $SU(3) \\times SU(2)_L \\times U(1)_Y$ of the standard model. Based on the scale-invariant HLS, we evaluate the coupling properties of the technirho mesons and place limits on the masses from the current LHC data. Then, implications for future LHC phenomenology are discussed by focusing on the technirho mesons produced through the Drell-Yan process. We find that the color-octet technirho decaying to the technidilaton along with the gluon is of interest as the discovery channel at the LHC, which would provide a characteristic signature to probe the one-family WTC.
Walking capabilities of Gregor controlled through Walknet
NASA Astrophysics Data System (ADS)
Arena, Paolo; Patané, Luca; Schilling, Malte; Schmitz, Josef
2007-05-01
Locomotion control of legged robots is nowadays a field in continuous evolution. In this work a bio-inspired control architecture based on the stick insect is applied to control the hexapod robot Gregor. The control scheme is an extension of Walknet, a decentralized network inspired by the stick insect, that on the basis of local reflexes generates the control signals needed to coordinate locomotion in hexapod robots. Walknet has been adapted to the specific mechanical structure of Gregor that is characterized by specialized legs and a sprawled posture. In particular an innovative hind leg geometry, inspired by the cockroach, has been considered to improve climbing capabilities. The performances of the new control architecture have been evaluated in dynamic simulation environments. The robot has been endowed with distance and contact sensors for obstacle detection. A heading control is used to avoid large obstacles, and an avoidance reflex, as can be found in stick insects, has been introduced to further improve climbing capabilities of the structure. The reported results, obtained in different environmental configurations, stress the adaptive capabilities of the Walknet approach: Even in unpredictable and cluttered environments the walking behaviour of the simulated robot and the robot prototype, controlled through a FPGA based board, remained stable.
Walking technipions in a holographic model
NASA Astrophysics Data System (ADS)
Kurachi, Masafumi; Matsuzaki, Shinya; Yamawaki, Koichi
2014-11-01
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.
ISWI Remodels Nucleosomes through a Random Walk
2015-01-01
The chromatin remodeler ISWI is capable of repositioning clusters of nucleosomes to create well-ordered arrays or moving single nucleosomes from the center of DNA fragments toward the ends without disrupting their integrity. Using standard electrophoresis assays, we have monitored the ISWI-catalyzed repositioning of different nucleosome samples each containing a different length of DNA symmetrically flanking the initially centrally positioned histone octamer. We find that ISWI moves the histone octamer between distinct and thermodynamically stable positions on the DNA according to a random walk mechanism. Through the application of a spectrophotometric assay for nucleosome repositioning, we further characterized the repositioning activity of ISWI using short nucleosome substrates and were able to determine the macroscopic rate of nucleosome repositioning by ISWI. Additionally, quantitative analysis of repositioning experiments performed at various ISWI concentrations revealed that a monomeric ISWI is sufficient to obtain the observed repositioning activity as the presence of a second ISWI bound had no effect on the rate of nucleosome repositioning. We also found that ATP hydrolysis is poorly coupled to nucleosome repositioning, suggesting that DNA translocation by ISWI is not energetically rate-limiting for the repositioning reaction. This is the first calculation of a microscopic ATPase coupling efficiency for nucleosome repositioning and also further supports our conclusion that a second bound ISWI does not contribute to the repositioning reaction. PMID:24898619
Walking while talking: investigation of alternate forms.
Brandler, Tamar C; Oh-Park, Mooyeon; Wang, Cuiling; Holtzer, Roee; Verghese, Joe
2012-01-01
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
Liberating Lévy walk research from the shackles of optimal foraging.
Reynolds, Andy
2015-09-01
There is now compelling evidence that many organisms have movement patterns that can be described as Lévy walks, or Lévy flights. Lévy movement patterns have been identified in cells, microorganisms, molluscs, insects, reptiles, fish, birds and even human hunter-gatherers. Most research into Lévy walks as models of organism movement patterns has been shaped by the 'Lévy flight foraging hypothesis'. This states that, since Lévy walks can optimize search efficiencies, natural selection should lead to adaptations that select ?for Lévy walk foraging. However, a growing body of research on generative mechanisms suggests that Lévy walks can arise freely as by-products of otherwise innocuous behaviours; consequently their advantageous properties are purely coincidental. This suggests that the Lévy flight foraging hypothesis should be amended, or even replaced, by a simpler and more general hypothesis. This new hypothesis would state that 'Lévy walks emerge spontaneously and naturally from innate behaviours and innocuous responses to the environment but, if advantageous, then there could be selection against losing them'. The new hypothesis has the virtue of making fewer assumptions and being broader than the original hypothesis; it also encompasses the many examples of suboptimal Lévy patterns that challenge the prevailing paradigm. This does not detract from the Lévy flight foraging hypothesis, in fact, it adds to the theory by providing a stronger and more compelling case for the occurrence of Lévy walks. It dispenses with concerns about the theoretical arguments in support of the Lévy flight foraging hypothesis and so may lead to a wider acceptance of Lévy walks as models of movement pattern data. Furthermore, organisms can approximate Lévy walks by adapting intrinsic behaviour in simple ways; this occurs when Lévy movement patterns are advantageous, but come with an associated cost. These new developments represent a major change in perspective and provide the broadest picture yet of Lévy movement patterns. However, the process of understanding and identifying Lévy movement patterns still has a long way to go, and further reinterpretations and shifts in understanding will occur. In conclusion, Lévy walk research remains exciting precisely because so much remains to be understood, and because, even relatively small studies, are interesting discoveries in their own right. PMID:25835600
Liberating Lévy walk research from the shackles of optimal foraging
NASA Astrophysics Data System (ADS)
Reynolds, Andy
2015-09-01
There is now compelling evidence that many organisms have movement patterns that can be described as Lévy walks, or Lévy flights. Lévy movement patterns have been identified in cells, microorganisms, molluscs, insects, reptiles, fish, birds and even human hunter-gatherers. Most research into Lévy walks as models of organism movement patterns has been shaped by the 'Lévy flight foraging hypothesis'. This states that, since Lévy walks can optimize search efficiencies, natural selection should lead to adaptations that select for Lévy walk foraging. However, a growing body of research on generative mechanisms suggests that Lévy walks can arise freely as by-products of otherwise innocuous behaviours; consequently their advantageous properties are purely coincidental. This suggests that the Lévy flight foraging hypothesis should be amended, or even replaced, by a simpler and more general hypothesis. This new hypothesis would state that 'Lévy walks emerge spontaneously and naturally from innate behaviours and innocuous responses to the environment but, if advantageous, then there could be selection against losing them'. The new hypothesis has the virtue of making fewer assumptions and being broader than the original hypothesis; it also encompasses the many examples of suboptimal Lévy patterns that challenge the prevailing paradigm. This does not detract from the Lévy flight foraging hypothesis, in fact, it adds to the theory by providing a stronger and more compelling case for the occurrence of Lévy walks. It dispenses with concerns about the theoretical arguments in support of the Lévy flight foraging hypothesis and so may lead to a wider acceptance of Lévy walks as models of movement pattern data. Furthermore, organisms can approximate Lévy walks by adapting intrinsic behaviour in simple ways; this occurs when Lévy movement patterns are advantageous, but come with an associated cost. These new developments represent a major change in perspective and provide the broadest picture yet of Lévy movement patterns. However, the process of understanding and identifying Lévy movement patterns still has a long way to go, and further reinterpretations and shifts in understanding will occur. In conclusion, Lévy walk research remains exciting precisely because so much remains to be understood, and because, even relatively small studies, are interesting discoveries in their own right.
Walking Adaptability after a Stroke and Its Assessment in Clinical Settings
Balasubramanian, Chitralakshmi K.; Clark, David J.; Fox, Emily J.
2014-01-01
Control of walking has been described by a tripartite model consisting of stepping, equilibrium, and adaptability. This review focuses on walking adaptability, which is defined as the ability to modify walking to meet task goals and environmental demands. Walking adaptability is crucial to safe ambulation in the home and community environments and is often severely compromised after a stroke. Yet quantification of walking adaptability after stroke has received relatively little attention in the clinical setting. The objectives of this review were to examine the conceptual challenges for clinical measurement of walking adaptability and summarize the current state of clinical assessment for walking adaptability. We created nine domains of walking adaptability from dimensions of community mobility to address the conceptual challenges in measurement and reviewed performance-based clinical assessments of walking to determine if the assessments measure walking adaptability in these domains. Our literature review suggests the lack of a comprehensive well-tested clinical assessment tool for measuring walking adaptability. Accordingly, recommendations for the development of a comprehensive clinical assessment of walking adaptability after stroke have been presented. Such a clinical assessment will be essential for gauging recovery of walking adaptability with rehabilitation and for motivating novel strategies to enhance recovery of walking adaptability after stroke. PMID:25254140
Increased walking variability in elderly persons with congestive heart failure
NASA Technical Reports Server (NTRS)
Hausdorff, J. M.; Forman, D. E.; Ladin, Z.; Goldberger, A. L.; Rigney, D. R.; Wei, J. Y.
1994-01-01
OBJECTIVES: To determine the effects of congestive heart failure on a person's ability to walk at a steady pace while ambulating at a self-determined rate. SETTING: Beth Israel Hospital, Boston, a primary and tertiary teaching hospital, and a social activity center for elderly adults living in the community. PARTICIPANTS: Eleven elderly subjects (aged 70-93 years) with well compensated congestive heart failure (NY Heart Association class I or II), seven elderly subjects (aged 70-79 years) without congestive heart failure, and 10 healthy young adult subjects (aged 20-30 years). MEASUREMENTS: Subjects walked for 8 minutes on level ground at their own selected walking rate. Footswitches were used to measure the time between steps. Step rate (steps/minute) and step rate variability were calculated for the entire walking period, for 30 seconds during the first minute of the walk, for 30 seconds during the last minute of the walk, and for the 30-second period when each subject's step rate variability was minimal. Group means and 5% and 95% confidence intervals were computed. MAIN RESULTS: All measures of walking variability were significantly increased in the elderly subjects with congestive heart failure, intermediate in the elderly controls, and lowest in the young subjects. There was no overlap between the three groups using the minimal 30-second variability (elderly CHF vs elderly controls: P < 0.001, elderly controls vs young: P < 0.001), and no overlap between elderly subjects with and without congestive heart failure when using the overall variability. For all four measures, there was no overlap in any of the confidence intervals, and all group means were significantly different (P < 0.05).
Dalfampridine Effects Beyond Walking Speed in Multiple Sclerosis
Fjeldstad, Cecilie; Suárez, Gustavo; Klingler, Michael; Henney, Herbert R.; Rabinowicz, Adrian L.
2015-01-01
Background: Dalfampridine extended release (ER) improves walking in people with multiple sclerosis (MS), as demonstrated by walking speed improvement. This exploratory study evaluated treatment effects of dalfampridine-ER on gait, balance, and walking through treatment withdrawal and reinitiation. Methods: Dalfampridine-ER responders, based on Timed 25-Foot Walk (T25FW) assessment before study entry, were included in this open-label, three-period, single-center study. Period 1: on-drug evaluations performed at screening and 1 week after screening. Period 2: dalfampridine-ER withdrawal and off-drug evaluations (days 5 and 11). Period 3: dalfampridine-ER reinitiation/final on-drug evaluation (day 15). Primary outcome variables: NeuroCom composite scores for gait and balance; balance was evaluated if gait changes were significant. Secondary variables: individual NeuroCom scores, walking speed (T25FW) and distance (2-Minute Walk Test [2MWT]), and balance (Berg Balance Scale [BBS]). Results: All 20 patients completed the study: mean age, 53.1 years; mean MS duration, 11.3 years; mean time taking dalfampridine-ER, 315.3 days. NeuroCom gait composite scores worsened during period 2 relative to period 1 and improved during period 3; the mean ± SD difference in gait composite scores on drug was 4.03 ± 1.51 points (P = .015). Balance composite scores did not change significantly. Improvements were observed for off-drug versus on-drug for T25FW (0.36 ft/sec, P < .001), 2MWT (25.4 ft, P = .006), and BBS (1.7 points, P = .003). Safety profile was consistent with previous studies. Conclusions: Significant improvements in gait, walking speed, distance, and balance were demonstrated by dalfampridine-ER reinitiation after a 10-day withdrawal period.
A mechanical protocol to replicate impact in walking footwear.
Price, Carina; Cooper, Glen; Graham-Smith, Philip; Jones, Richard
2014-01-01
Impact testing is undertaken to quantify the shock absorption characteristics of footwear. The current widely reported mechanical testing method mimics the heel impact in running and therefore applies excessive energy to walking footwear. The purpose of this study was to modify the ASTM protocol F1614 (Procedure A) to better represent walking gait. This was achieved by collecting kinematic and kinetic data while participants walked in four different styles of walking footwear (trainer, oxford shoe, flip-flop and triple-density sandal). The quantified heel-velocity and effective mass at ground-impact were then replicated in a mechanical protocol. The kinematic data identified different impact characteristics in the footwear styles. Significantly faster heel velocity towards the floor was recorded walking in the toe-post sandals (flip-flop and triple-density sandal) compared with other conditions (e.g. flip-flop: 0.36±0.05 ms(-1) versus trainer: 0.18±0.06 ms(-1)). The mechanical protocol was adapted by altering the mass and drop height specific to the data captured for each shoe (e.g. flip-flop: drop height 7 mm, mass 16.2 kg). As expected, the adapted mechanical protocol produced significantly lower peak force and accelerometer values than the ASTM protocol (p<.001). The mean difference between the human and adapted protocol was 12.7±17.5% (p<.001) for peak acceleration and 25.2±17.7% (p=.786) for peak force. This paper demonstrates that altered mechanical test protocols can more closely replicate loading on the lower limb in walking. This therefore suggests that testing of material properties of footbeds not only needs to be gait style specific (e.g. running versus walking), but also footwear style specific. PMID:24618371
Biomechanics and energetics of walking on uneven terrain
Voloshina, Alexandra S.; Kuo, Arthur D.; Daley, Monica A.; Ferris, Daniel P.
2013-01-01
SUMMARY Walking on uneven terrain is more energetically costly than walking on smooth ground, but the biomechanical factors that contribute to this increase are unknown. To identify possible factors, we constructed an uneven terrain treadmill that allowed us to record biomechanical, electromyographic and metabolic energetics data from human subjects. We hypothesized that walking on uneven terrain would increase step width and length variability, joint mechanical work and muscle co-activation compared with walking on smooth terrain. We tested healthy subjects (N=11) walking at 1.0 m s?1, and found that, when walking on uneven terrain with up to 2.5 cm variation, subjects decreased their step length by 4% and did not significantly change their step width, while both step length and width variability increased significantly (22 and 36%, respectively; P<0.05). Uneven terrain walking caused a 28 and 62% increase in positive knee and hip work, respectively, and a 26% greater magnitude of negative knee work (0.0106, 0.1078 and 0.0425 J kg?1, respectively; P<0.05). Mean muscle activity increased in seven muscles in the lower leg and thigh (P<0.05). These changes caused overall net metabolic energy expenditure to increase by 0.73 W kg?1 (28%; P<0.0001). Much of that increase could be explained by the increased mechanical work observed at the knee and hip. Greater muscle co-activation could also contribute to increased energetic cost but to unknown degree. The findings provide insight into how lower limb muscles are used differently for natural terrain compared with laboratory conditions. PMID:23913951
Random walks of internal visual states.
Wexler, Mark; Mamassian, Pascal
2015-09-01
We have previously (Wexler & Mamassian, VSS 2014) reported that there exist two independent biases related to the perception of 3D shape and motion from optic flow. These biases are both robust within observers, and highly variable across observers. Here we present a quantitative analysis of time series of these two variables, sampled once a day over three months in 97 observers. The temporal power spectra and autocorrelation structure of these time series show that they do not consist of independent samples from fixed distributions ("white noise"), but rather depend on internal variables that undergo cumulative changes over time. This observation is amplified by an analysis in the Box-Jenkins ARIMA framework, which shows that in most observers the time series are well modeled as random walks (or "Brownian motion") with superimposed measurement noise. Thus, we have evidence that the perception of at least two families of visual stimuli is governed by internal variables. Further, we show that (1) these variables can change both in response to external stimuli and perturbations, as well as during periods of complete darkness, showing that at least some of their dynamics is internal in origin; (2) the biases are strong enough to withstand a fair amount of counter-evidence from other depth cues; (3) the variables may not be single-valued but are actually vector fields over the visual field, with non-trivial spatial and temporal structure; (4) there are at least two more independent internal variables for 2D motion, corresponding to steps of 1D gratings and the motion quartet. The dynamic behavior of these variables opens a window on the internal dynamics of the visual system. Meeting abstract presented at VSS 2015. PMID:26326991
Mitra, Raktim; Siva, Herthana; Kehler, Mark
2015-12-01
The neighbourhood environment may enable active aging by allowing the integration of walking into an older adult's daily routine. This study explores the relationship between the neighbourhood built environment and walking among a small group of older adults in a large suburban municipality in Canada. In-depth interviews using a photo-voice approach revealed that the participants walked largely to accumulated physical activity. Older adults who lived in either conventional residential or condominium neighbourhoods discussed poor traffic conditions and lack of benches/trees/places as barriers, and proximity to parks and access to shops as enablers to walking. Poor sidewalk quality, absence of street lights and personal safety concerns were major barriers to walking only for those living in suburban residential neighbourhoods. Our results indicate that high quality- and safe walking infrastructure may facilitate walking for physical activity among older adults living in the suburban communities. PMID:26568210
Neighbourhood walkability, daily steps and utilitarian walking in Canadian adults
Hajna, Samantha; Ross, Nancy A; Joseph, Lawrence; Harper, Sam; Dasgupta, Kaberi
2015-01-01
Objectives To estimate the associations of neighbourhood walkability (based on Geographic Information System (GIS)-derived measures of street connectivity, land use mix, and population density and the Walk Score) with self-reported utilitarian walking and accelerometer-assessed daily steps in Canadian adults. Design A cross-sectional analysis of data collected as part of the Canadian Health Measures Survey (2007–2009). Setting Home neighbourhoods (500?m polygonal street network buffers around the centroid of the participant's postal code) located in Atlantic Canada, Québec, Ontario, the Prairies and British Columbia. Participants 5605 individuals participated in the survey. 3727 adults (?18?years) completed a computer-assisted interview and attended a mobile clinic assessment. Analyses were based on those who had complete exposure, outcome and covariate data (n=2949). Main exposure measures GIS-derived walkability (based on land use mix, street connectivity and population density); Walk Score. Main outcome measures Self-reported utilitarian walking; accelerometer-assessed daily steps. Results No important relationship was observed between neighbourhood walkability and daily steps. Participants who reported more utilitarian walking, however, accumulated more steps (<1?h/week: 6613 steps/day, 95% CI 6251 to 6975; 1 to 5?h/week: 6768 steps/day, 95% CI 6420 to 7117; ?6?h/week: 7391 steps/day, 95% CI 6972 to 7811). There was a positive graded association between walkability and odds of walking ?1?h/week for utilitarian purposes (eg, Q4 vs Q1 of GIS-derived walkability: OR=1.66, 95% CI 1.31 to 2.11; Q3 vs Q1: OR=1.41, 95% CI 1.14 to 1.76; Q2 vs Q1: OR=1.13, 95% CI 0.91 to 1.39) independent of age, sex, body mass index, married/common law status, annual household income, having children in the household, immigrant status, mood disorder, perceived health, ever smoker and season. Conclusions Contrary to expectations, living in more walkable Canadian neighbourhoods was not associated with more total walking. Utilitarian walking and daily steps were, however, correlated and walkability demonstrated a positive graded relationship with utilitarian walking. PMID:26603246
EMG patterns during assisted walking in the exoskeleton
Sylos-Labini, Francesca; La Scaleia, Valentina; d'Avella, Andrea; Pisotta, Iolanda; Tamburella, Federica; Scivoletto, Giorgio; Molinari, Marco; Wang, Shiqian; Wang, Letian; van Asseldonk, Edwin; van der Kooij, Herman; Hoellinger, Thomas; Cheron, Guy; Thorsteinsson, Freygardur; Ilzkovitz, Michel; Gancet, Jeremi; Hauffe, Ralf; Zanov, Frank; Lacquaniti, Francesco; Ivanenko, Yuri P.
2014-01-01
Neuroprosthetic technology and robotic exoskeletons are being developed to facilitate stepping, reduce muscle efforts, and promote motor recovery. Nevertheless, the guidance forces of an exoskeleton may influence the sensory inputs, sensorimotor interactions and resulting muscle activity patterns during stepping. The aim of this study was to report the muscle activation patterns in a sample of intact and injured subjects while walking with a robotic exoskeleton and, in particular, to quantify the level of muscle activity during assisted gait. We recorded electromyographic (EMG) activity of different leg and arm muscles during overground walking in an exoskeleton in six healthy individuals and four spinal cord injury (SCI) participants. In SCI patients, EMG activity of the upper limb muscles was augmented while activation of leg muscles was typically small. Contrary to our expectations, however, in neurologically intact subjects, EMG activity of leg muscles was similar or even larger during exoskeleton-assisted walking compared to normal overground walking. In addition, significant variations in the EMG waveforms were found across different walking conditions. The most variable pattern was observed in the hamstring muscles. Overall, the results are consistent with a non-linear reorganization of the locomotor output when using the robotic stepping devices. The findings may contribute to our understanding of human-machine interactions and adaptation of locomotor activity patterns. PMID:24982628
A discrete time random walk model for anomalous diffusion
NASA Astrophysics Data System (ADS)
Angstmann, C. N.; Donnelly, I. C.; Henry, B. I.; Nichols, J. A.
2015-07-01
The continuous time random walk, introduced in the physics literature by Montroll and Weiss, has been widely used to model anomalous diffusion in external force fields. One of the features of this model is that the governing equations for the evolution of the probability density function, in the diffusion limit, can generally be simplified using fractional calculus. This has in turn led to intensive research efforts over the past decade to develop robust numerical methods for the governing equations, represented as fractional partial differential equations. Here we introduce a discrete time random walk that can also be used to model anomalous diffusion in an external force field. The governing evolution equations for the probability density function share the continuous time random walk diffusion limit. Thus the discrete time random walk provides a novel numerical method for solving anomalous diffusion equations in the diffusion limit, including the fractional Fokker-Planck equation. This method has the clear advantage that the discretisation of the diffusion limit equation, which is necessary for numerical analysis, is itself a well defined physical process. Some examples using the discrete time random walk to provide numerical solutions of the probability density function for anomalous subdiffusion, including forcing, are provided.
Quantum walk coherences on a dynamical percolation graph
Elster, Fabian; Barkhofen, Sonja; Nitsche, Thomas; Novotný, Jaroslav; Gábris, Aurél; Jex, Igor; Silberhorn, Christine
2015-01-01
Coherent evolution governs the behaviour of all quantum systems, but in nature it is often subjected to influence of a classical environment. For analysing quantum transport phenomena quantum walks emerge as suitable model systems. In particular, quantum walks on percolation structures constitute an attractive platform for studying open system dynamics of random media. Here, we present an implementation of quantum walks differing from the previous experiments by achieving dynamical control of the underlying graph structure. We demonstrate the evolution of an optical time-multiplexed quantum walk over six double steps, revealing the intricate interplay between the internal and external degrees of freedom. The observation of clear non-Markovian signatures in the coin space testifies the high coherence of the implementation and the extraordinary degree of control of all system parameters. Our work is the proof-of-principle experiment of a quantum walk on a dynamical percolation graph, paving the way towards complex simulation of quantum transport in random media. PMID:26311434
A university, community coalition, and town partnership to promote walking.
Griffin, Sarah F; Williams, Joel E; Hickman, Powell; Kirchner, Amber; Spitler, Hugh
2011-01-01
Less than half of all US adults report meeting physical activity recommendations of 30 minutes or more of moderate to vigorous physical activity on at least 5 days per week. Thus, community-wide ecological initiatives are needed to create environments that support incorporating physical activity into residents' daily lives. In this article we describe an ongoing collaborative service-learning partnership between Clemson University, a community coalition, and a neighboring small rural town to address local social and physical environment supports for walking. Years 1 to 3 of this collaborative initiative were evaluated using a mixed-method approach to assess physical environment changes, social environment changes, community perceptions of support for walking, community perceptions of collaborating with university students, and students' skill development. Results revealed several key environmental changes such as mapping and marking 3 walking trails in the community, development of broad marketing efforts linked to the trails that promote community health and heritage, and annual community events to promote walking and the newly developed walking trails. Interview data with community leaders identified several key themes critical to facilitating and enhancing our university and community collaboration. Lastly, students developed skills in developing partnerships, mapping, advocacy, event planning, critical reflection, and qualitative and quantitative data collection and analysis. Through this process community members and students learn evidence-based public health skills for using data and planning frameworks to guide local initiatives, engage community members in decision making, and conducting evaluations. PMID:21617413
Robotic-assessment of walking in individuals with gait disorders.
Hidler, J
2004-01-01
Walking deficits are a common bi-product of numerous neurological injuries, such as stroke and spinal cord injury. A number of new therapeutic interventions, such as body-weight supported locomotor training and robotic technologies aim to improve walking function and reduce co-morbidities. Currently, there is no way to determine what the optimal set of training parameters are for maximizing step performance. This paper presents a technique for estimating the walking performance of individuals with gait disorders using a robotic-orthosis. The device, called the Lokomat is coupled to the subject through instrumented leg cuffs, while the split-belt treadmill on which the subject walks is instrumented with piezo-electric force sensors allowing for the calculation of ground reaction forces and center of pressure. Using this data, a real-time inverse dynamics approach can be used to estimate the kinetics and kinematics of the subject, and when combined with electromyographic (EMG) data, the set of training conditions through which the subject generates the most appropriate EMG patterns and joint moments can be identified. The proposed technique will for the first time provide clinicians a way of determining the optimal gait training parameters for each individual, and also track their functional recovery throughout their neurorehabilitation program. It is postulated that training at the conditions that maximizes stepping performance will lead to higher gains in over-ground walking ability. PMID:17271392
Quantum walk coherences on a dynamical percolation graph.
Elster, Fabian; Barkhofen, Sonja; Nitsche, Thomas; Novotný, Jaroslav; Gábris, Aurél; Jex, Igor; Silberhorn, Christine
2015-01-01
Coherent evolution governs the behaviour of all quantum systems, but in nature it is often subjected to influence of a classical environment. For analysing quantum transport phenomena quantum walks emerge as suitable model systems. In particular, quantum walks on percolation structures constitute an attractive platform for studying open system dynamics of random media. Here, we present an implementation of quantum walks differing from the previous experiments by achieving dynamical control of the underlying graph structure. We demonstrate the evolution of an optical time-multiplexed quantum walk over six double steps, revealing the intricate interplay between the internal and external degrees of freedom. The observation of clear non-Markovian signatures in the coin space testifies the high coherence of the implementation and the extraordinary degree of control of all system parameters. Our work is the proof-of-principle experiment of a quantum walk on a dynamical percolation graph, paving the way towards complex simulation of quantum transport in random media. PMID:26311434
Procter-Gray, Elizabeth; Leveille, Suzanne G.; Hannan, Marian T.; Cheng, Jie; Kane, Kevin; Li, Wenjun
2015-01-01
Background. Regular walking is critical to maintaining health in older age. We examined influences of individual and community factors on walking habits in older adults. Methods. We analyzed walking habits among participants of a prospective cohort study of 745 community-dwelling men and women, mainly aged 70 years or older. We estimated community variations in utilitarian and recreational walking, and examined whether the variations were attributable to community differences in individual and environmental factors. Results. Prevalence of recreational walking was relatively uniform while prevalence of utilitarian walking varied across the 16 communities in the study area. Both types of walking were associated with individual health and physical abilities. However, utilitarian walking was also strongly associated with several measures of neighborhood socioeconomic status and access to amenities while recreational walking was not. Conclusions. Utilitarian walking is strongly influenced by neighborhood environment, but intrinsic factors may be more important for recreational walking. Communities with the highest overall walking prevalence were those with the most utilitarian walkers. Public health promotion of regular walking should take this into account. PMID:26339507
Ladouceur, M; Barbeau, H
2000-03-01
This study investigated the changes in maximal overground walking speed (MOWS) that occurred during walking training with a functional electrical stimulation (FES) orthosis by chronic spinal cord injured persons with incomplete motor function loss. The average walking speed over a distance of 10 m was calculated while the participants (n = 14) used their FES orthosis with and without power as well as with the various ambulatory assistive devices available. Within the first year of use, walking with an FES orthosis facilitated use of more advanced ambulatory assistive devices (10/14), improvements in functional mobility (12/14) and increases in the combined (0.26 m/s) and therapeutic (0.25 m/s) MOWS that were correlated (combined: r = 0.57; therapeutic: r = 0.69) with their respective initial MOWS. A longitudinal analysis showed that increases in MOWS followed a pattern of changes best described by either an exponential association (8/12) or a linear (4/12) model. These changes were similar for the combined and therapeutic MOWS (7/11) as well as for the different ambulatory assistive devices (8/9). It is concluded that the increased MOWS during walking training using the FES orthosis is mostly due to a therapeutic effect, implying that mechanisms of plasticity occur during such a training paradigm. PMID:10782939
Convergence of a random walk method for the Burgers equation
Roberts, S.
1985-10-01
In this paper we consider a random walk algorithm for the solution of Burgers' equation. The algorithm uses the method of fractional steps. The non-linear advection term of the equation is solved by advecting ''fluid'' particles in a velocity field induced by the particles. The diffusion term of the equation is approximated by adding an appropriate random perturbation to the positions of the particles. Though the algorithm is inefficient as a method for solving Burgers' equation, it does model a similar method, the random vortex method, which has been used extensively to solve the incompressible Navier-Stokes equations. The purpose of this paper is to demonstrate the strong convergence of our random walk method and so provide a model for the proof of convergence for more complex random walk algorithms; for instance, the random vortex method without boundaries.
Towards holographic walking from N=4 super Yang-Mills
S. Prem Kumar; David Mateos; Angel Paredes; Maurizio Piai
2010-12-21
We propose that a holographic description of `walking' behaviour, namely quasi-conformal dynamics relevant for technicolor models, can be obtained from relevant deformations of N=4 super Yang-Mills. We consider deformations which drive the theory close to the N=1 Leigh-Strassler fixed point, eventually deviating from it in the deep IR. We use the Pilch-Warner dual supergravity description of the flow between the N=4 and the N=1 fixed points to focus on observables that only require knowledge of the walking region. These include large anomalous dimensions of quark bilinear operators, which we study via probe D7-branes. We also make a first attempt at describing the theory beyond the walking region by introducing an infrared cut-off, in the spirit of hard-wall models. In this case we find a light, dilaton-like scalar state, but whether this mode persists in the exact theory remains an open question.