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Sample records for walking distance

  1. Claimed walking distance of lower limb amputees

    NARCIS (Netherlands)

    Geertzen, JHB; Bosmans, JC; Van der Schans, CP; Dijkstra, PU

    2005-01-01

    Purpose: Walking ability in general and specifically for lower limb amputees is of major importance for social mobility and ADL independence. Walking determines prosthesis prescription. The aim of this study was to mathematically analyse factors influencing claimed walking distance of lower limb amp

  2. Simple expressions for the long walk distance

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    Chebotarev, Pavel; Balaji, R

    2011-01-01

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

  3. Walking pattern classification and walking distance estimation algorithms using gait phase information.

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    Wang, Jeen-Shing; Lin, Che-Wei; Yang, Ya-Ting C; Ho, Yu-Jen

    2012-10-01

    This paper presents a walking pattern classification and a walking distance estimation algorithm using gait phase information. A gait phase information retrieval algorithm was developed to analyze the duration of the phases in a gait cycle (i.e., stance, push-off, swing, and heel-strike phases). Based on the gait phase information, a decision tree based on the relations between gait phases was constructed for classifying three different walking patterns (level walking, walking upstairs, and walking downstairs). Gait phase information was also used for developing a walking distance estimation algorithm. The walking distance estimation algorithm consists of the processes of step count and step length estimation. The proposed walking pattern classification and walking distance estimation algorithm have been validated by a series of experiments. The accuracy of the proposed walking pattern classification was 98.87%, 95.45%, and 95.00% for level walking, walking upstairs, and walking downstairs, respectively. The accuracy of the proposed walking distance estimation algorithm was 96.42% over a walking distance.

  4. Multiobjective Gate Assignment Based on Passenger Walking Distance and Fairness

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    Yu Jiang

    2013-01-01

    Full Text Available Passenger walking distance is an important index of the airport service quality. How to shorten the walking distance and balance the airlines' service quality is the focus of much research on airport gate assignment problems. According to the problems of airport passenger service quality, an optimization gate assignment model is established. The gate assignment model is based on minimizing the total walking distance of all passengers and balancing the average walking distance of passengers among different airlines. Lingo is used in the simulation of a large airport gate assignment. Test results show that the optimization model can reduce the average walking distance of passenger effectively, improve the number of flights assigned to gate, balance airline service quality, and enhance the overall service level of airports and airlines. The model provides reference for the airport gate preassignment.

  5. Plantar pressure changes after long-distance walking.

    NARCIS (Netherlands)

    Stolwijk, N.M.; Duysens, J.E.J.; Louwerens, J.W.; Keijsers, N.L.

    2010-01-01

    PURPOSE: The popularity of long-distance walking (LDW) has increased in the last decades. However, the effects of LDW on plantar pressure distribution and foot complaints, in particular, after several days of walking, have not been studied. METHODS: We obtained the plantar pressure data of 62

  6. Stride Counting in Human Walking and Walking Distance Estimation Using Insole Sensors

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    Truong, Phuc Huu; Lee, Jinwook; Kwon, Ae-Ran; Jeong, Gu-Min

    2016-01-01

    This paper proposes a novel method of estimating walking distance based on a precise counting of walking strides using insole sensors. We use an inertial triaxial accelerometer and eight pressure sensors installed in the insole of a shoe to record walkers’ movement data. The data is then transmitted to a smartphone to filter out noise and determine stance and swing phases. Based on phase information, we count the number of strides traveled and estimate the movement distance. To evaluate the accuracy of the proposed method, we created two walking databases on seven healthy participants and tested the proposed method. The first database, which is called the short distance database, consists of collected data from all seven healthy subjects walking on a 16 m distance. The second one, named the long distance database, is constructed from walking data of three healthy subjects who have participated in the short database for an 89 m distance. The experimental results show that the proposed method performs walking distance estimation accurately with the mean error rates of 4.8% and 3.1% for the short and long distance databases, respectively. Moreover, the maximum difference of the swing phase determination with respect to time is 0.08 s and 0.06 s for starting and stopping points of swing phases, respectively. Therefore, the stride counting method provides a highly precise result when subjects walk. PMID:27271634

  7. Stride Counting in Human Walking and Walking Distance Estimation Using Insole Sensors

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    Phuc Huu Truong

    2016-06-01

    Full Text Available This paper proposes a novel method of estimating walking distance based on a precise counting of walking strides using insole sensors. We use an inertial triaxial accelerometer and eight pressure sensors installed in the insole of a shoe to record walkers’ movement data. The data is then transmitted to a smartphone to filter out noise and determine stance and swing phases. Based on phase information, we count the number of strides traveled and estimate the movement distance. To evaluate the accuracy of the proposed method, we created two walking databases on seven healthy participants and tested the proposed method. The first database, which is called the short distance database, consists of collected data from all seven healthy subjects walking on a 16 m distance. The second one, named the long distance database, is constructed from walking data of three healthy subjects who have participated in the short database for an 89 m distance. The experimental results show that the proposed method performs walking distance estimation accurately with the mean error rates of 4.8% and 3.1% for the short and long distance databases, respectively. Moreover, the maximum difference of the swing phase determination with respect to time is 0.08 s and 0.06 s for starting and stopping points of swing phases, respectively. Therefore, the stride counting method provides a highly precise result when subjects walk.

  8. Does walking strategy in older people change as a function of walking distance?

    NARCIS (Netherlands)

    Najafi, Bijan; Helbostad, Jorunn L.; Moe-Nilssen, Rolf; Zijlstra, Wiebren; Aminian, Kamiar

    2009-01-01

    This study investigates whether the spatio-temporal parameters of gait in the elderly vary as a function of walking distance. The gait pattern of older subjects (n = 27) over both short (SWD <10 m) and long (LWD > 20 in) walking was evaluated using an ambulatory device consisting of body-worn sensor

  9. Walking speed and distance in different environments of subjects in the later stage post-stroke.

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    Carvalho, Cristiane; Sunnerhagen, Katharina S; Willén, Carin

    2010-11-01

    The purpose of this study is to assess short- and long-distance walking performance in indoor and outdoor environments of slow and fast walkers' subjects living in the community in the later stage post-stroke. Thirty-six subjects with at least 6 months post-stroke were included and divided into two groups based on their walking speed in the clinical setting. Thirty-meter walk tests (30 mWT) at self-selected and maximum speeds were assessed in three environments: (1) clinical setting; (2) basement setting; and (3) outdoor setting. Six-minute walk test (6 MWT) distance was assessed in the clinical and outdoor settings. The differences between the 30 mWT and the 6 MWT, as measured by the actual distance obtained in the 6 MWT and the predicted distance calculated for the 30 mWT, were also investigated. There was no difference in walking speed when subjects performed short-distance walking in different environments. However, a difference was found in performance of long-distance walking. Subjects who walked 0.8 m/s or faster also walked further in the outdoor setting. The findings of our study demonstrate that in those who scored below 0.8 m/s, performance of short- and long-distance walking evaluated in an indoor environment reflects the results obtained in an outdoor environment. However, for subjects post-stroke who score 0.8 m/s or faster, distance was increased in the outdoor environments during long-distance walking. Walking speed obtained over a short distance seemed to overestimate long-distance walking capacity for the slow walkers, despite the environment.

  10. Minimal walking distance following exercise treatment in patients with arterial occlusive disease.

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    Rosetzsky, A; Struckmann, J; Mathiesen, F R

    1985-01-01

    79 patients with intermittent claudication were tested with peripheral blood pressure measurement and determination of minimal walking distance before and after a 3 months' period with scheduled walking exercises under supervision. No change in peripheral blood pressure was observed following the treatment whereas the minimum walking distance was increased with statistical significance. The gain was most pronounced in patients with an initial combination of high peripheral pressures and short walking distances. A graphic presentation allows for the estimation of the expected gain in individual patients with claudication.

  11. Determinants of 6-minute walk distance in patients with idiopathic pulmonary fibrosis undergoing lung transplant evaluation.

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    Porteous, Mary K; Rivera-Lebron, Belinda N; Kreider, Maryl; Lee, James; Kawut, Steven M

    2016-03-01

    Little is known about the physiologic determinants of 6-minute walk distance in idiopathic pulmonary fibrosis. We investigated the demographic, pulmonary function, echocardiographic, and hemodynamic determinants of 6-minute walk distance in patients with idiopathic pulmonary fibrosis evaluated for lung transplantation. We performed a cross-sectional analysis of 130 patients with idiopathic pulmonary fibrosis who completed a lung transplantation evaluation at the Hospital of the University of Pennsylvania between 2005 and 2010. Multivariable linear regression analysis was used to generate an explanatory model for 6-minute walk distance. After adjustment for age, sex, race, height, and weight, the presence of right ventricular dilation was associated with a decrease of 50.9 m (95% confidence interval [CI], 8.4-93.3) in 6-minute walk distance ([Formula: see text]). For each 200-mL reduction in forced vital capacity, the walk distance decreased by 15.0 m (95% CI, 9.0-21.1; [Formula: see text]). For every increase of 1 Wood unit in pulmonary vascular resistance, the walk distance decreased by 17.3 m (95% CI, 5.1-29.5; [Formula: see text]). Six-minute walk distance in idiopathic pulmonary fibrosis depends in part on circulatory impairment and the degree of restrictive lung disease. Future trials that target right ventricular morphology, pulmonary vascular resistance, and forced vital capacity may potentially improve exercise capacity in patients with idiopathic pulmonary fibrosis.

  12. Effect of concurrent walking and interlocutor distance on conversational speech intensity and rate in Parkinson's disease.

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    McCaig, Cassandra M; Adams, Scott G; Dykstra, Allyson D; Jog, Mandar

    2016-01-01

    Previous studies have demonstrated a negative effect of concurrent walking and talking on gait in Parkinson's disease (PD) but there is limited information about the effect of concurrent walking on speech production. The present study examined the effect of sitting, standing, and three concurrent walking tasks (slow, normal, fast) on conversational speech intensity and speech rate in fifteen individuals with hypophonia related to idiopathic Parkinson's disease (PD) and fourteen age-equivalent controls. Interlocuter (talker-to-talker) distance effects and walking speed were also examined. Concurrent walking was found to produce a significant increase in speech intensity, relative to standing and sitting, in both the control and PD groups. Faster walking produced significantly greater speech intensity than slower walking. Concurrent walking had no effect on speech rate. Concurrent walking and talking produced significant reductions in walking speed in both the control and PD groups. In general, the results of the present study indicate that concurrent walking tasks and the speed of concurrent walking can have a significant positive effect on conversational speech intensity. These positive, "energizing" effects need to be given consideration in future attempts to develop a comprehensive model of speech intensity regulation and they may have important implications for the development of new evaluation and treatment procedures for individuals with hypophonia related to PD.

  13. Walking Behavior of Zoo Elephants: Associations between GPS-Measured Daily Walking Distances and Environmental Factors, Social Factors, and Welfare Indicators.

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    Matthew R Holdgate

    Full Text Available Research with humans and other animals suggests that walking benefits physical health. Perhaps because these links have been demonstrated in other species, it has been suggested that walking is important to elephant welfare, and that zoo elephant exhibits should be designed to allow for more walking. Our study is the first to address this suggestion empirically by measuring the mean daily walking distance of elephants in North American zoos, determining the factors that are associated with variations in walking distance, and testing for associations between walking and welfare indicators. We used anklets equipped with GPS data loggers to measure outdoor daily walking distance in 56 adult female African (n = 33 and Asian (n = 23 elephants housed in 30 North American zoos. We collected 259 days of data and determined associations between distance walked and social, housing, management, and demographic factors. Elephants walked an average of 5.3 km/day with no significant difference between species. In our multivariable model, more diverse feeding regimens were correlated with increased walking, and elephants who were fed on a temporally unpredictable feeding schedule walked 1.29 km/day more than elephants fed on a predictable schedule. Distance walked was also positively correlated with an increase in the number of social groupings and negatively correlated with age. We found a small but significant negative correlation between distance walked and nighttime Space Experience, but no other associations between walking distances and exhibit size were found. Finally, distance walked was not related to health or behavioral outcomes including foot health, joint health, body condition, and the performance of stereotypic behavior, suggesting that more research is necessary to determine explicitly how differences in walking may impact elephant welfare.

  14. Motor fatigue measurement by distance-induced slow down of walking speed in multiple sclerosis.

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    Rémy Phan-Ba

    Full Text Available BACKGROUND AND RATIONALE: Motor fatigue and ambulation impairment are prominent clinical features of people with multiple sclerosis (pMS. We hypothesized that a multimodal and comparative assessment of walking speed on short and long distance would allow a better delineation and quantification of gait fatigability in pMS. Our objectives were to compare 4 walking paradigms: the timed 25-foot walk (T25FW, a corrected version of the T25FW with dynamic start (T25FW(+, the timed 100-meter walk (T100MW and the timed 500-meter walk (T500MW. METHODS: Thirty controls and 81 pMS performed the 4 walking tests in a single study visit. RESULTS: The 4 walking tests were performed with a slower WS in pMS compared to controls even in subgroups with minimal disability. The finishing speed of the last 100-meter of the T500MW was the slowest measurable WS whereas the T25FW(+ provided the fastest measurable WS. The ratio between such slowest and fastest WS (Deceleration Index, DI was significantly lower only in pMS with EDSS 4.0-6.0, a pyramidal or cerebellar functional system score reaching 3 or a maximum reported walking distance ≤ 4000 m. CONCLUSION: The motor fatigue which triggers gait deceleration over a sustained effort in pMS can be measured by the WS ratio between performances on a very short distance and the finishing pace on a longer more demanding task. The absolute walking speed is abnormal early in MS whatever the distance of effort when patients are unaware of ambulation impairment. In contrast, the DI-measured ambulation fatigability appears to take place later in the disease course.

  15. Comparison of the distances covered during 3 and 6 min walking test.

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    Iriberri, Milagros; Gáldiz, Juan Bta; Gorostiza, Amaia; Ansola, Pedro; Jaca, Carmen

    2002-10-01

    To determine the reproducibility of the distance covered in 3 min and its correlation with the 6 min walking test, as well as compare the distances covered at different time intervals. Secondly, to evaluate the relationship between the distances covered during these time periods and the maximum oxygen intake obtained during a bicycle ergometer test. Forty-five Chronic Obstructive Pulmonary Disesase patients were included in the study. Subjects who were either physically limited or familiar with the test, or those with acute exacerbation in the month prior to the study, were excluded. Three walking tests were carried out each day. In 30 patients for three consecutive days, and the distances covered in periods of 3 and 6 min were measured with 20 min rest between each walk. No incentive was given and the patients knew that the distances covered in 3 and 6 min would be quantified. Oxygen saturation, heart rate and degree of breathlessness (modified Borg scale) were registered at baseline. After 3 min, the distance covered and degree of breathlessness were also measured. After 6 min, oxygen saturation, heart rate, degree of breathlessness and distance covered in meters were registered. Spirometry was performed daily on each patient, and those with an FEV1 variation of less than 10% were considered clinically and functionally stable. An exercise test using bicycle ergometer was carried out to determine maximum oxygen intake. A 3 min walking test was performed in 15 patients, independently on the same day, which was followed after 20 min rest with a 6 min walking test. A significant increase was observed in the distance covered over 3 and 6 min in the first 5 walks, with the greatest increase seen in the first 3 walks. The correlation between the distance covered in 3 and 6 min was 0.98. The correlation between the distance covered in 3 min and oxygen intake was 0.64. No significant differences were observed between the distances covered in the 0-3 and 3 to 6 min periods

  16. Educational Triage in Open Distance Learning: Walking a Moral Tightrope

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    Prinsloo, Paul; Slade, Sharon

    2014-01-01

    Higher education, and more specifically, distance education, is in the midst of a rapidly changing environment. Higher education institutions increasingly rely on the harvesting and analyses of student data to inform key strategic decisions across a wide range of issues, including marketing, enrolment, curriculum development, the appointment of…

  17. Self-reported maximum walking distance in persons with MS may affect the EDSS.

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    Berger, Warren; Payne, Michael W C; Morrow, Sarah A

    2017-08-15

    In persons with MS (PwMS), the Expanded Disability Status Scale (EDSS) is used to monitor disability progression. Scores between 4.0 and 7.0 are determined by maximum walking distance. Self-estimation of this value is often employed in clinic settings. To examine the accuracy with which PwMS estimate their walking distance, and observe subsequent changes to the EDSS. This prospective cohort study recruited PwMS with previously recorded EDSS of 3.5-7.0. Participants estimated their maximum walking distance and then walked as far as they could along a pre-specified course. Each distance was converted to an EDSS score, the "estimated EDSS" and the "actual EDSS". Chi-Square analysis was used to compare EDSS scores. Logistic regression was used to determine predictors of inaccurate estimations. Of the 66 PwMS in this study, 43.9% had a difference in the actual EDSS compared to the estimated EDSS. Median estimated EDSS was 4.75 (range 3.0-7.0); after walking assessment, median actual EDSS was 5.0 (range 3.0-7.0), which represented a significant difference [X(2) (df 64, N=66)=206.9; pEDSS decreased in 9 PwMS (13.6%) and increased in 20 PwMS (30.3%). Logistic regression did not find any demographic/disease characteristic to be predictive of this discrepancy. Some PwMS do not accurately estimate maximum walking distance; only 56.1% of PwMS accurately estimated their actual EDSS. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Educational Triage in Open Distance Learning: Walking a Moral Tightrope

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    Paul Prinsloo

    2014-09-01

    Full Text Available Higher education, and more specifically, distance education, is in the midst of a rapidly changing environment. Higher education institutions increasingly rely on the harvesting and analyses of student data to inform key strategic decisions across a wide range of issues, including marketing, enrolment, curriculum development, the appointment of staff, and student assessment. In the light of persistent concerns regarding student success and retention in distance education contexts, the harvesting and analysis of student data in particular in the emerging field of learning analytics holds much promise. As such the notion of educational triage needs to be interrogated. Educational triage is defined as balancing between the futility or impact of the intervention juxtaposed with the number of students requiring care, the scope of care required, and the resources available for care/interventions. The central question posed by this article is “how do we make moral decisions when resources are (increasingly limited?” An attempt is made to address this by discussing the use of data to support decisions regarding student support and examining the concept of educational triage. Despite the increase in examples of institutions implementing a triage based approach to student support, there is a serious lack of supporting conceptual and theoretical development, and, more importantly, to consideration of the moral cost of triage in educational settings. This article provides a conceptual framework to realise the potential of educational triage to responsibly and ethically respond to legitimate concerns about the “revolving door” in distance and online learning and the sustainability of higher education, without compromising ‘openness.’ The conceptual framework does not attempt to provide a detailed map, but rather a compass consisting of principles to consider in using learning analytics to classify students according to their perceived risk of

  19. A botanical compound, Padma 28, increases walking distance in stable intermittent claudication

    DEFF Research Database (Denmark)

    Drabaek, H; Mehlsen, J; Himmelstrup, H

    1993-01-01

    and by measurements of the pain-free and the maximal walking distance on a treadmill. The ankle pressure index (ankle systolic pressure/arm systolic pressure) was calculated. The group randomized to active treatment received two tablets bid containing 340 mg of a dried herbal mixture composed according to an ancient...

  20. Effects of Walking Speed and Visual-Target Distance on Toe Trajectory During Swing Phase

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    Miller, Chris; Peters, Brian; Brady, Rachel; Warren, Liz; Richards, Jason; Mulavara, Ajitkumar; Sung, Hsi-Guang; Bloomberg, Jacob

    2006-01-01

    After spaceflight, astronauts experience disturbances in their ability to walk and maintain postural stability (Bloomberg, et al., 1997). One of the post-flight neurovestibular assessments requires that the astronaut walk on a treadmill at 1.8 m/sec (4.0 mph), while performing a visual acuity test, set at two different distances ( far and near ). For the first few days after landing, some crewmembers can not maintain the required pace, so a lower speed may be used. The slower velocity must be considered in the kinematic analysis, because Andriacchi, et al. (1977) showed that in clinical populations, changes in gait parameters may be attributable more to slower gait speed than pathology. Studying toe trajectory gives a global view of control of the leg, since it involves coordination of muscles and joints in both the swing and stance legs (Karst, et al., 1999). Winter (1992) and Murray, et al. (1984) reported that toe clearance during overground walking increased slightly as speed increased, but not significantly. Also, toe vertical peaks in both early and late swing phase did increase significantly with increasing speed. During conventional testing of overground locomotion, subjects are usually asked to fix their gaze on the end of the walkway a far target. But target (i.e., visual fixation) distance has been shown to affect head and trunk motion during treadmill walking (Bloomberg, et al., 1992; Peters, et al., in review). Since the head and trunk can not maintain stable gaze without proper coordination with the lower body (Mulavara & Bloomberg, 2003), it would stand to reason that lower body kinematics may be altered as well when target distance is modified. The purpose of this study was to determine changes in toe vertical trajectory during treadmill walking due to changes in walking speed and target distance.

  1. Relationships between weekly walking distance and adiposity in27,596 women are nonlinear with respect to both distance andadiposity

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    Williams, Paul T.

    2004-12-01

    The cross-sectional relationships of weekly walking distance to BMI, body circumferences, and bra cup sizes are reported for 27,596 women. The percent reductions between walking 40-50 km/wk and < 10km/wk were greatest for BMI, substantial for waist circumference and cupsize, and least for hip and chest circumferences. The relationships between distance and adiposity were nonlinear with respect to both the independent (quadratic function of distance) and dependent variables(slope and curvilinearity depending upon the percentile of BMI, circumference, or cup size). The slope relating adiposity to km/wk were greatest (most negative) in overweight sedentary women and least in lean active women. For example, compared to women averaging 10 km/wk, the slope of BMI versus km/wk was 43 percent less at 25 km/wk and 87 percent less at 40 km/wk in overweight women (95th BMI percentile), but negligible at all distances in lean women (5th BMI percentile). The greater estimated decrease in BMI per km/wk in walkers than runners was largely accounted for (over 75 percent) by the walkers greater adiposity. Thus classical representations of the relationship between adiposity and moderate physical activity are inadequate for either statistical analyses or descriptive purposes. The clinical implications of these results and their statistical ramifications are discussed.

  2. Walking ability following knee arthroplasty: a prospective pilot study of factors affecting the maximal walking distance in 18 patients before and 6 months after total knee arthroplasty.

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    Rosenberg, N; Nierenberg, G; Lenger, R; Soudry, M

    2007-12-01

    Functional assessment of patients before and after prosthetic knee arthroplasty is based on clinical examination, which is usually summarized in various knee scores. The present study proposes a different and more subject orientated assessment for functional grading of these patients by measuring their maximal distance of walking ability, which is not apparent from the conventional outcome scores. Eighteen consecutive patients with knee osteoarthritis were evaluated for their knee and knee functional scores (The Knee Society clinical rating system) and for the maximal distance of their walking ability before and 6 months after knee arthroplasty. Specially designed walking ability grading was used for evaluation of walking on walkway. The pre- and post-operative knee scores and maximal walking distance and grading were statistically compared. A significant improvement in the knee and functional scores following surgery was observed. But the maximal walking ability grades and distances did not change significantly following surgery, showing a high relation between pre- and post-operative values. The limitation in post-operative walking was due to the revealed additional health disabilities, not related to the affected knee. Therefore we suggest that pre-operative evaluation of walking abilities should be taken into consideration both for patients' selection and timing of surgery and also for matching of patients' expectation from outcome of prosthetic knee arthroplasty.

  3. Impaired Economy of Gait and Decreased Six-Minute Walk Distance in Parkinson's Disease

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    Leslie I. Katzel

    2012-01-01

    Full Text Available Changes in the biomechanics of gait may alter the energy requirements of walking in Parkinson's Disease (PD. This study investigated economy of gait during submaximal treadmill walking in 79 subjects with mild to moderate PD and the relationship between gait economy and 6-minute walk distance (6 MW. Oxygen consumption (VO2 at the self-selected treadmill walking speed averaged 64% of peak oxygen consumption (VO2 peak. Submaximal VO2 levels exceeded 70% of VO2 peak in 30% of the subjects. Overall the mean submaximal VO2 was 51% higher than VO2 levels expected for the speed and grade consistent with severe impairment in economy of gait. There was an inverse relationship between economy of gait and 6MW (r=−0.31, P<0.01 and with the self-selected walking speed (r=−0.35, P<0.01. Thus, the impairment in economy of gait and decreased physiologic reserve result in routine walking being performed at a high percentage of VO2 peak.

  4. Six-Minute-Walk Distance Predicts Waiting List Survival in Idiopathic Pulmonary Fibrosis

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    Lederer, David J.; Arcasoy, Selim M.; Wilt, Jessie S.; D'Ovidio, Frank; Sonett, Joshua R.; Kawut, Steven M.

    2006-01-01

    Rationale: Functional studies may be useful to predict survival in idiopathic pulmonary fibrosis (IPF). Various cutoffs of 6-min-walk distance (6MWD) have been suggested to identify patients at a high risk of death. Objectives: To examine the association between 6MWD and survival in patients with IPF listed for lung transplantation, and to identify sensitive and specific cutoffs for predicting death at 6 mo. Methods: We performed a retrospective cohort study of 454 patients classified as having IPF listed for lung transplantation with the United Network for Organ Sharing between June 30, 2004 and July 22, 2005. Measurements and Main Results: Lower 6MWD was associated with an increased mortality rate (p value for linear trend < 0.0001). Patients with a walk distance less than 207 m had a more than fourfold greater mortality rate than those with a walk distance of 207 m or more, despite adjustment for demographics, anthropomorphics, FVC % predicted, pulmonary hypertension, and medical comorbidities (adjusted rate ratio, 4.7; 95% confidence interval, 2.5–8.9; p < 0.0001). 6MWD was a significantly better predictor of 6-mo mortality than was FVC % predicted (c-statistic = 0.73 vs. 0.59, respectively; p = 0.02). Conclusions: Lower 6MWD was strongly and independently associated with an increased mortality rate for wait-listed patients classified as having IPF. 6MWD was a better predictor of death at 6 mo than was FVC % predicted. PMID:16778159

  5. Finite element analysis of sliding distance and contact mechanics of hip implant under dynamic walking conditions.

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    Gao, Yongchang; Jin, Zhongmin; Wang, Ling; Wang, Manyi

    2015-06-01

    An explicit finite element method was developed to predict the dynamic behavior of the contact mechanics for a hip implant under normal walking conditions. Two key parameters of mesh sensitivity and time steps were examined to balance the accuracy and computational cost. Both the maximum contact pressure and accumulated sliding distance showed good agreement with those in the previous studies using the implicit finite element analysis and analytical methods. Therefore, the explicit finite element method could be used to predict the contact pressure and accumulated sliding distance for an artificial hip joint simultaneously in dynamic manner.

  6. Heart rate recovery after the 6-min walk test is related to 6-min walk distance and percutaneous oxygen saturation recovery in patients with COPD.

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    Shiroishi, Ryota; Kitagawa, Chika; Miyamoto, Naomi; Kakuno, Nao; Koyanagi, Harumi; Rikitomi, Naoto; Senjyu, Hideaki

    2015-05-01

    Heart rate recovery (HRR) after maximal load exercise affects mortality in chronic obstructive pulmonary disease (COPD). However, the associations of clinical characteristics with HRR after the 6-min walk test (6MWT), which is defined as a submaximal load test, remain unclear. We showed that HRR in patients with COPD after 6MWT was related to 6-min walk distance and percutaneous oxygen saturation recovery. HRR after the 6MWT may be useful to assess exercise capacity in COPD.

  7. The relationship between anthropometric indicators and walking distance in patients with chronic obstructive pulmonary disease

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    Ho SC

    2015-09-01

    Full Text Available Shu-Chuan Ho,1,* Min-Fang Hsu,2,3,* Han-Pin Kuo,4 Jiun-Yi Wang,2 Li-Fei Chen,4 Kang-Yun Lee,5,6 Hsiao-Chi Chuang11School of Respiratory Therapy, College of Medicine, Taipei Medical University, Taipei, 2Department of Healthcare Administration, Asia University, Wufeng, Taichung, 3Department of Nursing, Kang-Ning Junior College of Medical Care and Management, Taipei, 4Department of Thoracic Medicine, Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Taipei, 5Division of Pulmonary Medicine, Department of Internal Medicine, Shuang Ho Hospital, 6Department of Internal Medicine, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan*These authors contributed equally to this workBackground: Exercise intolerance is a major issue affecting many people with COPD. Six-minute walking distance (6MWD is a widely used indicator of exercise capacity in patients with COPD. The process is strenuous and time-consuming, especially for patients who have muscle wasting. Anthropometric indicators that reflect body lean mass, such as body mass index (BMI, mid-arm circumference (MAC, and calf circumference (CC, may have value in predicting exercise intolerance.Purpose: This study attempted to determine the abilities of simple anthropometric indicators including BMI, MAC, and CC in reflecting the exercise intolerance of COPD patients.Methods: We recruited 136 nonhospitalized ambulatory COPD patients without acute conditions from a general hospital in Taiwan. Each subject’s BMI, MAC, and CC were measured, and they were examined with pulmonary function tests and a 6-minute walk test.Results: Among the three anthropometric indicators examined, CC showed the strongest correlation with the 6MWD, followed by MAC and BMI. CC was also strongly associated with functional capacity, followed by MAC, according to the receiver operating characteristic curves. CC and MAC, but not BMI, were significantly associated with exercise

  8. A STUDY TO DETERMINE THE REFERENCE VALUES FOR TWO MINUTE WALK DISTANCE IN HEALTHY INDIAN ADULTS

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    T. Krishna Priya

    2015-10-01

    Full Text Available Background: The use of functional scales to assess the prognosis of the individuals is widely being encouraged by the International classification of Functioning, Disability and Health. Two, six and twelve minute walk tests are the existing functional walk tests, among which 6MWT is being considered as the gold standard. Patients in acute stages of illnesses and early stages of recovery, it is difficult and tiring to accomplish a 6MWT. 2MWT is presently being used as a pre and post-test. To comment on the status of the patient and the test results in the first attempt, it is necessary to look at the reference values of 2MWT. Purpose of the study: This study aims to establish reference values for 2MWT in healthy Indian adults. Objective of the study: To establish reference values for 2 minute walk distance in healthy Indian adults of 20-80 years age. Methods: Three hundred subjects met the inclusion criteria through convenience sampling. Two trials of 2MWT were administered. Instructions for the test were adopted from American Thoracic Society guidelines for 6MWT. Out of the two trials, the one in which more distance was covered by the subject was taken for the analysis. Descriptive statistics were used to analyse the data. Results: The mean 2MWD was 182.69 + 32.40 meters. 2MWD had shown moderate significant negative correlation with age (r = -0.58 and weak but significant positive correlation with height (r = 0.35. The correlations with weight (r= 0.1 and BMI (r= -0.13 were found to be negligible. It was also found that males walked 21.55 + 3.5 meters more than females and aye2MWD during the second trial was found to be 3.011 + 1.44 meters greater than the first trial. Conclusion: The average distance covered by a healthy Indian individual is approximately 182.69 + 32.40 meters in 2 minutes duration. Implication: Patients in early stages of rehabilitation, early post-operative period and patients with severe disability, found 6MWT difficult

  9. Reference equations for the six-minute walk distance based on a Brazilian multicenter study.

    Science.gov (United States)

    Britto, Raquel R; Probst, Vanessa S; de Andrade, Armele F Dornelas; Samora, Giane A R; Hernandes, Nidia A; Marinho, Patrícia E M; Karsten, Marlus; Pitta, Fabio; Parreira, Veronica F

    2013-01-01

    It is important to include large sample sizes and different factors that influence the six-minute walking distance (6MWD) in order to propose reference equations for the six-minute walking test (6 MWT). To evaluate the influence of anthropometric, demographic, and physiologic variables on the 6 MWD of healthy subjects from different regions of Brazil to establish a reference equation for the Brazilian population. In a multicenter study, 617 healthy subjects performed two 6 MWTs and had their weight, height, and body mass index (BMI) measured, as well as their physiologic responses to the test. Delta heart rate (∆HR), perceived effort, and peripheral oxygen saturation were calculated by the difference between the respective values at the end of the test minus the baseline value. Walking distance averaged 586 ± 106 m, 54 m greater in male compared to female subjects (p<0.001). No differences were observed among the 6 MWD from different regions. The quadratic regression analysis considering only anthropometric and demographic data explained 46% of the variability in the 6 MWT (p<0.001) and derived the equation: 6 MWD(pred)=890.46-(6.11 × age)+(0.0345 × age(2))+(48.87 × gender)-(4.87 × BMI). A second model of stepwise multiple regression including ∆HR explained 62% of the variability (p<0.0001) and derived the equation: 6 MWD(pred)=356.658-(2.303 × age)+(36.648 × gender)+(1.704 × height)+(1.365×∆HR). The equations proposed in this study, especially the second one, seem adequate to accurately predict the 6 MWD for Brazilians.

  10. Regression equations to predict 6-minute walk distance in Chinese adults aged 55–85 years

    Directory of Open Access Journals (Sweden)

    Shirley P.C. Ngai, PhD

    2014-12-01

    Full Text Available The 6-minute walk distance (6MWD is used as a measure of functional exercise capacity in clinical populations and research. Reference equations to predict 6MWD in different populations have been established, however, available equations for Chinese population are scarce. This study aimed to develop regression equations to predict the 6MWD for a Hong Kong Chinese population. Fifty-three healthy individuals (25 men, 28 women; mean age = 69.3 ± 6.5 years participated in this cross-sectional study. Each participant performed two 6-minute walk tests (6MWTs in accordance with a standard protocol. Heart rate (HR was continuously monitored throughout the 6MWTs and the maximum HR was recorded. Measurements from the 6MWT that resulted in the highest 6MWD were used for regression analysis. The mean 6MWD was 563 ± 62 m and was significantly correlated with age (r = −0.62, height (r = 0.39, and percentage of predicted maximal HR (%predHRmax; r = 0.50. A regression equation derived from the data showed that age, sex, and %predHRmax were independent contributors and together explained 65% of the variance in 6MWD. When HR was excluded, the equation explained 52% of the variance. Application of these equations to a Chinese population living in different parts of China warrants further investigation.

  11. Screening for physical inactivity among adults: the value of distance walked in the six-minute walk test. A cross-sectional diagnostic study

    Directory of Open Access Journals (Sweden)

    Evandro Fornias Sperandio

    Full Text Available ABSTRACT: CONTEXT AND OBJECTIVES: Accelerometry provides objective measurement of physical activity levels, but is unfeasible in clinical practice. Thus, we aimed to identify physical fitness tests capable of predicting physical inactivity among adults. DESIGN AND SETTING: Diagnostic test study developed at a university laboratory and a diagnostic clinic. METHODS: 188 asymptomatic subjects underwent assessment of physical activity levels through accelerometry, ergospirometry on treadmill, body composition from bioelectrical impedance, isokinetic muscle function, postural balance on a force platform and six-minute walk test. We conducted descriptive analysis and multiple logistic regression including age, sex, oxygen uptake, body fat, center of pressure, quadriceps peak torque, distance covered in six-minute walk test and steps/day in the model, as predictors of physical inactivity. We also determined sensitivity (S, specificity (Sp and area under the curve of the main predictors by means of receiver operating characteristic curves. RESULTS: The prevalence of physical inactivity was 14%. The mean number of steps/day (≤ 5357 was the best predictor of physical inactivity (S = 99%; Sp = 82%. The best physical fitness test was a distance in the six-minute walk test and ≤ 96% of predicted values (S = 70%; Sp = 80%. Body fat > 25% was also significant (S = 83%; Sp = 51%. After logistic regression, steps/day and distance in the six-minute walk test remained predictors of physical inactivity. CONCLUSION: The six-minute walk test should be included in epidemiological studies as a simple and cheap tool for screening for physical inactivity.

  12. Echocardiographic Predictors for Worsening of Six-Minute Walk Distances in Patients With Systemic Sclerosis (Scleroderma).

    Science.gov (United States)

    Kusunose, Kenya; Yamada, Hirotsugu; Nishio, Susumu; Hirata, Yukina; Seno, Hiromitsu; Saijo, Yoshihito; Ise, Takayuki; Tobiume, Takeshi; Yamaguchi, Koji; Yagi, Shusuke; Soeki, Takeshi; Wakatsuki, Tetsuzo; Sata, Masataka

    2017-07-15

    Change in 6-minute walk distance (6MWD) has been used as a clinical marker in pulmonary hypertension. Determinants and worsening of 6MWD remain a matter of debate because nonpulmonary factors have an impact on the 6MWD. We hypothesized that future reduction of 6MWD in patients with systemic sclerosis (SSc) was more closely associated with cardiac dysfunction. We prospectively performed standard clinical and echocardiographic evaluations in SSc patients with the 6-minute walk test at enrollment. Features associated with the 6MWD were sought in a multiple linear regression analysis and compared using standardized β. Worsening of the 6MWD was defined as a 15% reduction and served as the primary outcome. Eighty-one patients were included. In the multivariate analysis, baseline 6MWD was related to SSc severity score (β = -0.250, p = 0.024), left atrial volume index (β = -0.222, p = 0.046), right ventricular fractional area change (β = 0.252, p = 0.025), and the ratio of mean pulmonary artery pressure and cardiac output (β = -0.31, p = 0.002). During follow-up, 20 patients reached the primary outcome. In sequential Cox models, a model based on right ventricular fractional area change at baseline (chi-square 4.8) was improved by left atrial volume index (chi-square 10.3, p = 0.007). In conclusion, determinants and worsening of 6MWD are explained by cardiac factors. When using the 6MWD as a clinical marker in pulmonary hypertension patients, their left ventricular diastolic function and right ventricular systolic function should be taken into consideration. Copyright © 2017 Elsevier Inc. All rights reserved.

  13. Distance to achieve steady state walking speed in frail elderly persons

    NARCIS (Netherlands)

    Lindemann, U.; Najafi, B.; Zijlstra, W.; Hauer, K.; Muche, R.; Becker, C.; Aminian, K.

    2008-01-01

    This study aims to determine the length of the gait initiation phase before achieving steady state walking in frail older people. Based on body fixed sensors, habitual walking was analysed in 116 community-dwelling older persons (mean age 83.1 years, 84% women). The start of steady state walking was

  14. Multimedia Exercise Training Program Improves Distance Walked, Heart Rate Recovery, and Self-efficacy in Cardiac Surgery Patients.

    Science.gov (United States)

    Wang, Li-Wei; Ou, Shu-Hua; Tsai, Chien-Sung; Chang, Yue-Cune; Kao, Chi-Wen

    2016-01-01

    Patient education has been shown to be more effective when delivered using multimedia than written materials. However, the effects of using multimedia to assist patients in cardiac rehabilitation have not been investigated. The purpose of this study is to examine the effect of an inpatient multimedia exercise training program on distance walked in the 6-minute walking test (6MWT), heart rate recovery, and walking self-efficacy of patients who had undergone heart surgery. For this longitudinal quasi-experimental study, 60 consecutive patients were assigned to an experimental (n = 20; inpatient multimedia exercise training program) or control (n = 40; routine care) group. Data were collected at 3 times (before surgery, 1 to 2 days before hospital discharge, and 1 month after hospital discharge) and analyzed with the generalized estimating equation approach. Most subjects were men (66.7%), had a mean age of 61.32 ± 13.4 years and left ventricular ejection fraction of 56.96% ± 13.28%, and underwent coronary artery bypass graft surgery (n = 34, 56.7%). Subjects receiving the exercise training program showed significantly greater improvement than those in the control group in the 6MWT walking distance (P surgery and maintained their improvement in 6MWT and self-efficacy 1 month later.

  15. Overweight-mortality paradox and impact of six-minute walk distance in lung transplantation

    Directory of Open Access Journals (Sweden)

    Kongkiat Chaikriangkrai

    2015-01-01

    Full Text Available Overweight-mortality paradox and impact of six-minute walk distance (SMWD in lung transplantation Background: The objective of this study was to examine combined prognostic influence of body mass index (BMI and SMWD on mortality in lung transplant recipients. Methods: Consecutive isolated lung transplant recipients were identified. Preoperative BMI and SMWD data were collected. The cohort was followed for all-cause mortality. Results: The study included 324 lung transplant recipients with mean age of 57 ± 13 years and 58% were male (27% obstructive, 3% vascular, 6% cystic fibrosis, and 64% with restrictive lung diseases. In the total cohort; 37% had normal BMI, 10% were underweight, 33% were overweight, and 20% were obese. The median SMWD was 700 feet. The lower SMWDgroup was defined as the patients who had SMWD <237 feet as determined by receiver operating characteristic (ROC. Based on this definition, 66 patients (20% had lower SMWD. There were 71 deaths during a median follow-up of 2.3 years. In multivariate analysis, both BMI and SMWD were independently associated with death. Being overweight was associated with reduced mortality risk (hazard ratio (HR 0.50, P = 0.042 compared to the normal BMI group, and this was primarily driven by early mortality posttransplant. This paradoxical overweight-mortality relationship remained significant in the lower SMWD group (HR 0.075, P = 0.018, but not in the higher SMWD group (P = 0.552. Conclusion: In lung transplant recipients under lung allocation score (LAS era, pretransplant BMI and SMWD were independent predictors for mortality after the transplant. The lowest mortality risk was noted in a group of transplant recipients identified as overweight; whereas, being underweight or obese was associated with increased mortality.

  16. School food environment: Quality and advertisement frequency of child-oriented packaged products within walking distance of public schools

    OpenAIRE

    Benjamin Missbach; Caterina Pachschwöll; Daniel Kuchling; Jürgen König

    2017-01-01

    Food marketing for children is a major concern for public health nutrition and many schools make efforts to increase healthy eating. Food environments surrounding schools in urban areas may undermine these efforts for healthy nutrition within school programs. Our study aim is to describe the nutrition environment within walking distance of schools in terms of food quality and food marketing and to explore the degree to which elements of the nutrition environment varies by proximity to schools...

  17. Six-minute walking distance and decrease in oxygen saturation during the six-minute walk test in pediatric pulmonary arterial hypertension.

    Science.gov (United States)

    Douwes, Johannes M; Hegeman, Anneke K; van der Krieke, Merel B; Roofthooft, Marcus T R; Hillege, Hans L; Berger, Rolf M F

    2016-01-01

    To investigate the prognostic value of the 6-minute walking distance (6-MWD), transcutaneous saturation (tcSO2) and heart rate (HR) obtained during the 6-minute walk test (6-MWT) in pediatric pulmonary arterial hypertension (PAH). This was an observational study with forty-seven pediatric PAH patients, aged ≥7 years, and diagnosed and followed at the national referral center for pediatric PAH in the Netherlands. All patients performed a comprehensive 6-minute walk test (6-MWT), which measures 6-MWD and tcSO2 and HR before ("baseline"), during ("exercise") and 5 min after ("recovery") the walk test. The 6-MWD expressed either in meters or in sex- and age-corrected z-scores, was associated with transplant-free survival, independently from sex, age, and the presence of a shunt-defect. Shorter 6-MWD correlated with higher WHO-FC and increased NT-pro-BNP. Absolute tcSO2 at exercise and tcSO2-decrease during 6-MWT were associated with transplant-free survival, independent from 6-MWD. Combining tcSO2-decrease with 6-MWD provided the strongest prognostic model. Patients with 6-MWD>352 m (the median 6-MWD) had a better outcome than those with smaller 6-MWD. A large tcSO2-decrease during 6-MWT (>19% for patients with and >5% for patients without a shunt defect) identified patients with worse transplant-free survival both in patients with a 6-MWD above and below the median 6-MWD. The 6-MWD is an independent predictor of prognosis in pediatric PAH, that reflects disease severity and clinically relevant exercise-tolerance and therefore qualifies as a treatment goal. The magnitude of tcSO2-decrease during 6-MWT, adjusted for the presence of a shunt, indicates an additional risk factor for prognosis in children with PAH. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  18. Layout Improvement Study to Reduce Staff Walking Distance in a Large Health Care Facility: How to Not Walk an Extra 4740 Miles.

    Science.gov (United States)

    Ley-Chavez, Adriana; Hmar-Lagroun, Tatiana; Douglas-Ntagha, Pamela; Cumbo, Charlotte L

    2016-01-01

    Inefficient facility layouts have been found to be a challenge in health care, with excessive walking adding to the demands of staff and creating delays, which can impact the quality of care. Minimizing unnecessary transportation during care delivery improves efficiency, reduces delays, and frees up resources for use on value-added activities. This article presents a methodology and application of facility design to improve responsiveness and efficiency at a large hospital. The approach described provides the opportunity to improve existing layouts in facilities in which the floor plan is already defined, but there is some flexibility to relocate key areas. The existing physical constraints and work flows are studied and taken into consideration, and the volume of traffic flow throughout the facility guides the decision of where to relocate areas for maximum efficiency. Details on the steps followed and general recommendations to perform the necessary process and data analyses are provided. We achieved a 34.8% reduction in distance walked (4740 miles saved per year) and a 30% reduction in floors traveled in elevators (344 931 floors, which translate to 842 hours spent using elevators) by relocating 4 areas in which frequently used resources are housed.

  19. Dual-tasking over an extended walking distance is associated with falls among community-dwelling older adults

    Directory of Open Access Journals (Sweden)

    Hirashima K

    2015-04-01

    Full Text Available Kenichi Hirashima,1,2 Yumi Higuchi,1 Masakazu Imaoka,1 Emiko Todo,1 Tomomi Kitagawa,1 Tetsuya Ueda11Graduate School of Comprehensive Rehabilitation, Osaka Prefecture University, Habikino Campus, Habikino City, Osaka, Japan; 2Faculty of Health and Welfare, Department of Physical Therapy, Tokushima Bunri University, Nishihamaboji, Yamashiro Town, Tokushima City, Tokushima, Japan Aim: Dual-task methods, in which walking is the primary task, are not sufficient for accurately screening for the risk of falls among healthy older adults. Therefore, the goal of this research was to investigate whether using a dual-task method over an extended walking distance can predict falls among community-dwelling older adults.Methods: We enrolled independent community-dwelling adults aged ≥65 years. Physical performance, cognitive function, psychological function, and a dual-task test were assessed at baseline. Our dual-task test required the subjects to walk 60 m while stepping over lines. The intervals between the lines ranged from 50–100 cm and were unequal. Falls and fall-related injuries were measured over a 12-month follow-up period using monthly postal surveys. Results: Ninety-two of 118 subjects (mean age, 75.4±5.5 years completed the 12-month follow-up. Sixteen (17.4% of fallers had injurious falls or fell more than or equal to two times. There were no significant differences between the fallers and non-fallers, except in age and in the number of missteps during the dual-task test when walking ≥40 m. The Kaplan–Meier analysis revealed that those who had more than one misstep while walking ≥40 m had a significantly higher incidence of injurious or multiple falls than those who had no missteps.Conclusion: Our findings suggest that the dual-task method with an extended walking distance may be able to predict falls among community-dwelling older adults. Keywords: cohort study, community-dwelling older adults, dual-task, falls

  20. Predicting outcomes from 6-minute walk distance in chronic obstructive pulmonary disease

    DEFF Research Database (Denmark)

    Spruit, Martijn A; Polkey, Michael I; Celli, Bartolome

    2012-01-01

    Exercise tolerance is an important clinical aspect of chronic obstructive pulmonary disease that can be easily and reliably measured with the 6-minute walking test (6MWT). To improve the utility of the 6MWT for patient and health care system management, the interpretation of the functional status...

  1. The effects of acebutolol and metoprolol on walking distances and distal blood pressure in hypertensive patients with intermittent claudication

    DEFF Research Database (Denmark)

    Svendsen, T L; Jelnes, Rolf; Tønnesen, K H

    1986-01-01

    The effects of acebutolol (with intrinsic sympathomimetic activity (ISA] and metoprolol (without ISA) on arm blood pressure, ankle systolic blood pressure, claudication distances (CD) and maximal walking distances (MWD) were compared in patients with essential hypertension and intermittent...... claudication. Fourteen patients participated in a long-term, open, randomized cross-over study. After randomization the patients received either acebutolol, 200 mg b.i.d., or metoprolol, 100 mg b.i.d. After eight weeks the drugs were shifted and after another eight weeks they were withdrawn. Arm and ankle...... blood pressure, CD and MWD were determined before randomization and after 4, 8, 12 and 16 weeks, and again 4-6 weeks after withdrawal of the drugs. The arm blood pressure was reduced by 20/13 mmHg after acebutolol and by 22/21 mmHg after metoprolol. In spite of a significant decrease in arm blood...

  2. Resident Walking Distance Threshold of Community%社区居民适宜步行距离阈值研究

    Institute of Scientific and Technical Information of China (English)

    王宁; 杜豫川

    2015-01-01

    The RP survey was conducted in districts of Shanghai to get the data of walking distance threshold, by asking residents′trip mode to particular destination and measuring of the actual walking distance between the destination and residents′shelter. Another questionnaire was carried out at Hongq⁃iao Transportation Hub to get the acceptable walking time. According to the data of walking distance and acceptable walking time, combining skewed distribution methods and distance decay equation, relation⁃ship between reasonable walking distance and usage of walking was calculated and two walking distance thresholds were obtained. The results show that calculated according to the survey of acceptable walking time, the limited walking distance is 1 500 meters, which could be used in overall design phase of urban planning;calculated according to the survey of walking distance, the limited walking distance is 950 me⁃ters, which could be used in selecting the location of specific functional area and traffic connection mode;the 787m walking distance which corresponds to 10%walking cumulative utilization rate is cho⁃sen as reasonable walking distance threshold.%为研究社区居民适宜步行距离阈值,在上海市进行小区内RP(Revealed Preference)调查,通过询问居民前往某处目的地的出行方式,实际测量居民住处到目的地的距离,得出步行距离;然后在虹桥火车站进行可接受步行时间的调查。综合步行距离和步行时间的数据,结合偏态分布与距离衰变方程的分析方法,得出适宜步行距离与步行使用率的关系式,并通过计算得到了距离阈值。结果表明,由可接受步行时间调查计算得到的极限步行距离阈值为1500m,适用于城市规划的整体设计阶段;由步行距离调查数据计算得到的极限步行距离阈值为950m,可用于具体功能区的选址及交通衔接方式的选取;选取步行累计使用率为10%

  3. The Long-Term Prognostic Significance of 6-Minute Walk Test Distance in Patients with Chronic Heart Failure

    Directory of Open Access Journals (Sweden)

    Lee Ingle

    2014-01-01

    Full Text Available Background. The 6-minute walk test (6-MWT is used to assess patients with chronic heart failure (CHF. The prognostic significance of the 6-MWT distance during long-term followup (>5 years is unclear. Methods. 1,667 patients (median [inter-quartile range, IQR] (age 72 [65–77]; 75% males with heart failure due to left ventricular systolic impairment undertook a 6-MWT as part of their baseline assessment and were followed up for 5 years. Results. At 5 years’ followup, those patients who died (n = 959 were older at baseline and had a higher log NT pro-BNP than those who survived to 5 years (n = 708. 6-MWT distance was lower in those who died [163 (153 m versus 269 (160 m; P 360 m. 6-MWT distance was a predictor of all-cause mortality (HR 0.97; 95% CI 0.96-0.97; Chi-square = 184.1; P < 0.0001. Independent predictors of all-cause mortality were decreasing 6-MWT distance, increasing age, increasing NYHA classification, increasing log NT pro-BNP, decreasing diastolic blood pressure, decreasing sodium, and increasing urea. Conclusion. The 6-MWT is an important independent predictor of all-cause mortality following long-term followup in patients with CHF.

  4. Transthoracic echocardiographic and cardiopulmonary exercise testing parameters in Eisenmenger's syndrome. Association with six-minute walk test distance.

    Science.gov (United States)

    Gungor, H; Fatih Ayik, M; Engin, C; Yagdi, T; Atay, Y; Ozbaran, M; Nalbantgil, S

    2014-08-01

    The six-minute walk test (6MWT) evaluates the functional exercise capacity in patients with cardiopulmonary disease. We aimed to investigate the association between 6MWT distance and transthoracic echocardiographic (TTE) findings as well as cardiopulmonary exercise testing (CPET) parameters in Eisenmenger's syndrome (ES) patients waiting for heart-lung transplantation on their initial admission to our center. A total of 23 patients with ES (12 women, 11 men; mean age, 28.2 ± 8.1 years) were included in the study. The correlation between 6MWT distance and CPET and TTE findings was retrospectively analyzed. The most frequent underlying heart diseases were ventricular septal defect (VSD) with complex congenital heart disease (n = 10, 43 %) and isolated VSD (n = 7, 30 %). The 6MWT distance was 349.7 ± 77.4 m in the study group. An inverse correlation was found between 6MWT distance and systolic pulmonary arterial pressure (SPAP) measured with TTE (r = - 0.445; p = 0.03). All patients underwent CPET at the first visit. Mean VO2 max was 14.9 ± 3.3 ml/kg/min and the VE/VCO2 rate was 50.4 ± 9.2 %. No significant correlation was observed between 6MWT and CPET findings. SPAP, which did not display any correlation with CPET findings, was the only independent predictor of 6MWT distance. We suggest that 6MWT distance may be more suitable than CPET in the follow-up of ES patients. Further prospective, randomized, controlled trials are necessary to make more robust interpretations of this issue.

  5. Effects of Different Backpack Loads in Acceleration Transmission during Recreational Distance Walking.

    Science.gov (United States)

    Lucas-Cuevas, Angel G; Pérez-Soriano, Pedro; Bush, Michael; Crossman, Aaron; Llana, Salvador; Cortell-Tormo, Juan M; Pérez-Turpin, José A

    2013-01-01

    It is well established nowadays the benefits that physical activity can have on the health of individuals. Walking is considered a fundamental method of movement and using a backpack is a common and economical manner of carrying load weight. Nevertheless, the shock wave produced by the impact forces when carrying a backpack can have detrimental effects on health status. Therefore, the aim of this study was to investigate differences in the accelerations placed on males and females whilst carrying different loads when walking. Twenty nine sports science students (16 males and 13 females) participated in the study under 3 different conditions: no weight, 10% and 20% body weight (BW) added in a backpack. Accelerometers were attached to the right shank and the centre of the forehead. Results showed that males have lower accelerations than females both in the head (2.62 ± 0.43G compared to 2.83 + 0.47G) and shank (1.37 ± 0.14G compared to 1.52 ± 0.15G; pbackpack condition (p>0.05). The body acts as a natural shock absorber, reducing the amount of force that transmits through the body between the foot (impact point) and head. Anthropometric and body mass distribution differences between males and females may result in women receiving greater impact acceleration compared to men when the same load is carried.

  6. Predictors of improvement in the 12-minute walking distance following a six-week outpatient pulmonary rehabilitation program.

    Science.gov (United States)

    Zu Wallack, R L; Patel, K; Reardon, J Z; Clark, B A; Normandin, E A

    1991-04-01

    We evaluated the relationship of clinical characteristics, pulmonary function, and exercise test data to the degree of improvement in the 12-minute walking distance (12MD) in 50 ambulatory outpatients completing a six-week pulmonary rehabilitation program. The 12MD increased by 27.7 +/- 32.5 percent, or 462 +/- 427 ft, by the end of the program. There were no significant relationships between improvement in the 12MD and age, sex, oxygen requirement, arterial blood gas levels, and pulmonary function; however, patients with a greater ventilatory reserve (1-[VEmax/MVV] x 100) had more improvement in their 12MD, both with respect to distance and percentage of increase over baseline. Additionally, patients with a lower peak oxygen consumption (VO2) and peak oxygen pulse (O2P) showed greater percentage of improvement in their 12MD. The magnitude of the initial 12MD was inversely related to its improvement, both with regard to distance (r = -0.43; r2 = 0.18; p less than 0.003) and percentage of increase (r = -0.71; r2 = 0.51; p less than 0.0001). Using stepwise regression, the combination of smaller initial 12MD and greater FEV1 was significantly predictive of improvement in the 12MD. Patients with poor performance on either a 12MD or maximal exercise test are not necessarily poor candidates for a pulmonary rehabilitation program.

  7. Estimating adhesive seed-dispersal distances : field experiments and correlated random walks

    NARCIS (Netherlands)

    Mouissie, AM; Lengkeek, W; van Diggelen, R

    1. In this study we aimed to estimate distance distributions of adhesively dispersed seeds and the factors that determine them. 2. Seed attachment and detachment were studied using field experiments with a real sheep, a sheep dummy and a cattle dummy. Seed-retention data were used in correlated

  8. The characteristics of multi-directional step distance and the association between stepping laterality and walking ability of patients with stroke.

    Science.gov (United States)

    Kobayashi, Masaki; Takahashi, Kumiko; Sato, Miyuki; Usuda, Shigeru

    2015-03-01

    [Purpose] The purpose of this study was to determine the effect of stepping limb and step direction on step distance and the association of step distance and stepping laterality in step difference with walking ability and motor dysfunction. [Subjects and Methods] The subjects were thirty-nine patients with chronic hemiparesis as a result of stroke, who performed the MSL (Maximum Step Length) test along with tests of motor impairment, gait speed and Functional Ambulation Category. The MSL test is a clinical test of stepping distance in which participants step to the front, side, and back. The subjects were classified into three groups according to the stepping laterality in front step distance. [Results] Step distance did not differ across stepping limbs but did differ across step directions. Front step distance was significantly longer than side and back step distance. Participants with forward paretic step length shorter than forward non-paretic step length had significantly higher walking ability than participants with symmetric forward step length or forward paretic step length longer than forward non-paretic step length [Conclusion] Patients with stroke have characteristic step distances in each direction. Adequate weight shift toward the paretic limb when stepping with the non-paretic limb is associated with walking ability.

  9. School food environment: Quality and advertisement frequency of child-oriented packaged products within walking distance of public schools

    Directory of Open Access Journals (Sweden)

    Benjamin Missbach

    2017-06-01

    Full Text Available Food marketing for children is a major concern for public health nutrition and many schools make efforts to increase healthy eating. Food environments surrounding schools in urban areas may undermine these efforts for healthy nutrition within school programs. Our study aim is to describe the nutrition environment within walking distance of schools in terms of food quality and food marketing and to explore the degree to which elements of the nutrition environment varies by proximity to schools. In a cross-sectional study, we analyzed the surrounding food environments of a convenience sample of 46 target schools within 950m walking distance in 7 different urban districts across Vienna, Austria. In total, we analyzed data from 67 fast food outlets and 54 supermarkets analyzing a total of 43.129 packaged snack food and beverage products, from which 85% were for adults and 15% of the products were child-oriented. Proximity to the schools did not affect the availability of child-oriented products and dedicated food advertisements for children. After applying nutrient profiling using the Nutrient Profiling Model (NPM on child-oriented products, results showed that 15.8% of the packaged snack food were categorized as “healthy” foods and 84.2% as “less healthy”; for beverages 65.7% were categorized as “healthy” and 34.3% as “less healthy”. In conclusion, our results show that child-oriented snacks are not more frequently advertised around schools but substantially lack in nutritional quality with the potential to undermine efforts for promoting healthy eating practices within schools.

  10. School food environment: Quality and advertisement frequency of child-oriented packaged products within walking distance of public schools.

    Science.gov (United States)

    Missbach, Benjamin; Pachschwöll, Caterina; Kuchling, Daniel; König, Jürgen

    2017-06-01

    Food marketing for children is a major concern for public health nutrition and many schools make efforts to increase healthy eating. Food environments surrounding schools in urban areas may undermine these efforts for healthy nutrition within school programs. Our study aim is to describe the nutrition environment within walking distance of schools in terms of food quality and food marketing and to explore the degree to which elements of the nutrition environment varies by proximity to schools. In a cross-sectional study, we analyzed the surrounding food environments of a convenience sample of 46 target schools within 950m walking distance in 7 different urban districts across Vienna, Austria. In total, we analyzed data from 67 fast food outlets and 54 supermarkets analyzing a total of 43.129 packaged snack food and beverage products, from which 85% were for adults and 15% of the products were child-oriented. Proximity to the schools did not affect the availability of child-oriented products and dedicated food advertisements for children. After applying nutrient profiling using the Nutrient Profiling Model (NPM) on child-oriented products, results showed that 15.8% of the packaged snack food were categorized as "healthy" foods and 84.2% as "less healthy"; for beverages 65.7% were categorized as "healthy" and 34.3% as "less healthy". In conclusion, our results show that child-oriented snacks are not more frequently advertised around schools but substantially lack in nutritional quality with the potential to undermine efforts for promoting healthy eating practices within schools.

  11. Changes in six-minute walking distance during pulmonary rehabilitation in patients with COPD and in healthy subjects

    Directory of Open Access Journals (Sweden)

    Imen Ben Cheikh Rejbi

    2010-07-01

    Full Text Available Imen Ben Cheikh Rejbi1, Yassine Trabelsi1, Afef Chouchene1, Wafa Ben Turkia1, Helmi Ben Saad1, Abdelkarim Zbidi1, Abdelhamid Kerken2, Zouhair Tabka11Department of Physiology and Lung Testing, Faculty of Medicine of Sousse, Tunisia; 2Department of Biophysics, Faculty of Medicine of Monastir, TunisiaBackground: The six-minute walking distance (6MWD test has demonstrated validity and reliability to assess changes in functional capacity following pulmonary rehabilitation in patients with chronic obstructive lung disease. However, no attempt has been made to establish an iterative measurement of 6MWD during the overall period of pulmonary rehabilitation. Therefore, the aim of this study was to evaluate the impact of a twelve-week rehabilitation program on the iterative weekly measurement of 6MWD in chronic obstructive pulmonary disease (COPD patients and healthy subjects.Methods: Twenty-six patients with COPD and nine age-matched healthy subjects were studied. Measurements were taken at baseline and after twelve weeks except for the 6MWD. The exercise measurements included a six-minute walking test (6MWT and an incremental exercise test. Oxygen saturation, heart rate, and dyspnea will be monitored during all these tests. Results: At baseline there were significant differences between groups, except in age, body mass index, and oxygen saturation. After 12 weeks, there was no significant change in lung function in patients with COPD and healthy subjects. The 6MWD, peak oxygen uptake VO2peak and anaerobic threshold increased significantly after training in both groups (P < 0.01. The averaged trace of the 6MWD of patients with COPD and healthy subjects was followed-up respectively by a logarithmic and linear fitting. 6MWD showed a plateau after eight weeks in patients with COPD, however, it increased continually overall in healthy subjects.Conclusion: Both patients with COPD and healthy subjects demonstrated functional responses to training but with

  12. Evaluations of Landscape Locations along Trails Based on Walking Experiences and Distances Traveled in the Akasawa Forest Therapy Base, Central Japan

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    Tong Zhang

    2015-08-01

    Full Text Available Forest planners are interested not only in forest spaces that visitors prefer but also in the preferred spatial arrangements of landscape features. In this study, we aimed to clarify walkers’ evaluations of four landscape locations composed of various scenic features in various spatial arrangements along forest walking routes. We also analyzed the trends, differences, and common features associated with different walking distances and experiences. The results are summarized as follows: (1 The walkers’ evaluations changed depending on the elements of the scene they observed and the spatial arrangements of those elements. The visitors preferred silent environments in forest spaces to the sounds of a stream. Meanwhile, they appreciated a good view in an open area. (2 The length of a walk prior to visiting a location on a route affected walkers’ evaluations of that location. For example, a special landscape feature was more positively rated by the respondents who visited the location late in their walks than those in the early and middle walking stages. However, the early-passage walkers were more pleased by touching natural objects such as rocks and large trees than those later in their walks. (3 Analysis revealed that the ratings of certain parameters differed according to the route taken to a location, whereas other ratings remain unchanged. Consequently, we must consider the effects of spatial properties of scenic factors on people’s perceptions in forest planning. (4 Walkers provided similar ratings on three parameters within forest landscapes—“Open feeling”, “Regular landscape” and “Natural” feel—even in the middle and near the end of their walks. Conversely, locations with water elements led to variations in parameter ratings that were maintained until the end of a person’s walk. Based on these results, we suggest that positive walking experiences can be maintained by considering the open feeling, regularity, and

  13. Serum Bilirubin and 6-min Walk Distance as Prognostic Predictors for Inoperable Chronic Thromboembolic Pulmonary Hypertension: A Prospective Cohort Study

    Institute of Scientific and Technical Information of China (English)

    Juan-Ni Gong; Zhen-Guo Zhai; Yuan-Hua Yang; Yan Liu; Song Gu; Tu-Guang Kuang; Wan-Mu Xie

    2015-01-01

    Background: Inoperable chronic thromboembolic pulmonary hypertension (CTEPH) is a severe clinical syndrome characterized by right cardiac failure and possibly subsequent liver dysfunction.However, whether serum markers of liver dysfunction can predict prognosis in inoperable CTEPH patients has not been determined.Our study aimed to evaluate the potential role of liver function markers (such as serum levels of transaminase, bilirubin, and gamma-glutamyl transpeptidase [GGT]) combined with 6-min walk test in the prediction of prognosis in patients with inoperable CTEPH.Methods: From June 2005 to May 2013, 77 consecutive patients with inoperable CTEPH without confounding co-morbidities were recruited for this prospective cohort study.Baseline clinical characteristics and 6-min walk distance (6MWD) results were collected.Serum biomarkers of liver function, including levels of aspartate aminotransferase, alanine aminotransferase, GGT, uric acid, and serum bilirubin, were also determined at enrollment.All-cause mortality was recorded during the follow-up period.Results: During the follow-up, 22 patients (29%) died.Cox regression analyses demonstrated that increased serum concentration of total bilirubin (hazard ratio [HR] =7.755, P < 0.001), elevated N-terminal of the prohormone brain natriuretic peptide (HR =1.001, P =0.001), decreased 6MWD (HR =0.990, P < 0.001), increased central venous pressure (HR =1.074, P =0.040), and higher pulmonary vascular resistance (HR =1.001, P =0.018) were associated with an increased risk of mortality.Serum concentrations of total bilirubin (HR =4.755, P =0.007) and 6MWD (HR =0.994, P =0.017) were independent prognostic predictors for CTEPH patients.Patients with hyperbilirubinemia (≥23.7 μ mol/L) had markedly worse survival than those with normobilirubinemia.Conclusion: Elevated serum bilirubin and decreased 6MWD are potential predictors for poor prognosis in inoperable CTEPH.

  14. A STUDY TO FIND THE CORRELATION BETWEEN SIX MINUTES WALK DISTANCE AND BLOOD GLUCOSE LEVEL IN DIABETIC PATIENTS

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    Swadita Dinakar

    2015-08-01

    Full Text Available Introduction: Physical activity has been recommended for patients with Type 2 Diabetes Mellitus (T2DM as it provides enormous physiological benefits by reducing the risk factors for development of complications, improves blood glucose control, overall health and quality of life. Formulation of an individualized exercise prescription based on exercise capacity and baseline plasma glucose levels is mandatory, as an exercise intensity which is considered moderate for one might turn out to be extremely rigorous for another patient with T2DM. Materials and Methods: The relationship between 6 minute walk test (6MWT & some correlates of T2DM was investigated in order to formulate an exercise prescription. This observational study of 102 T2DM patients from whom an informed consent was obtained, was conducted at the diabetic clinic of Sri Ramachandra medical college and research institute. The patients were instructed and made to perform a 6MWT according to ATS guidelines. The measurements included the 6-Minute Walk Distance (6MWD for exercise capacity and the T2DM correlates including age, gender, fasting blood glucose, post prandial blood glucose, HbA1C, duration of diabetes, BMI and waist hip ratio (WHR. Results: The relationships between the parameters were determined using Pearson’s correlation coefficient at a significance level of 0.05. The participants consisted of 55 males (53.1% & 47 females (46.1%. The mean 6MWD for males was 353.73±53.750mts & females was 317.55±58.037mts.The 6MWD correlated significantly (P 0.05 with WHR (r = 0.191 (females,r=-0.058 (males,duration of diabetes (r = -0.020 and age( r = -0.112. Conclusion: Thus low exercise capacity in patients with T2DM was associated with higher adiposity & poor glycaemic control. Therefore these factors should be given consideration when prescribing exercises for patients with T2DM in order to ensure safety and efficiency of the exercise session.

  15. Effects of noninvasive ventilation on treadmill 6-min walk distance and regional chest wall volumes in cystic fibrosis: randomized controlled trial.

    Science.gov (United States)

    Lima, Cibelle Andrade; Andrade, Armèle de Fátima Dornelas de; Campos, Shirley Lima; Brandão, Daniella Cunha; Fregonezi, Guilherme; Mourato, Ianny Pereira; Aliverti, Andrea; Britto, Murilo Carlos Amorim de

    2014-10-01

    Dyspnea and exercise intolerance are the symptoms that most affect the quality of life of children and adolescents with respiratory disorders resulting from cystic fibrosis (CF). To evaluate the effect of noninvasive ventilation (NIV) on treadmill 6-min walk distance and regional chest wall volumes in cystic fibrosis patients. Crossover clinical trial, randomized, controlled and open with 13 children and adolescents with CF, aged 7-16 years, with pulmonary impairment (NTC01987271). The patients performed a treadmill walking test (TWT) during 6 min, with and without NIV on a BiLEVEL mode, an interval of 24-48 h between tests. Before and after each test, patients were assessed by spirometry and optoelectronic plethysmography. Walking distance in TWT with NIV was significantly higher that without ventilatory support (mean ± sd: 0.41 ± 0.08 vs. 0.39 ± 0.85 km, p = 0.039). TWT with NIV increase forced expiratory volume on 1 s (FEV1; p = 0.036), tidal volume (Vt; p = 0.005), minute ventilation (MV; p = 0.013), pulmonary rib cage volume (Vrcp; p = 0.011), and decrease the abdominal volume (Vab; p = 0.013) after test. There was a significant reduction in oxygen saturation (p = 0.018) and permanent increase in respiratory rate after 5 min (p = 0.021) after the end test without NIV. During the walking test on the treadmill, the NIV change thoracoabdominal kinematics and lung function in order to optimized ventilation and tissue oxygenation, with improvement of walk distance. Consequently, NIV is an effective tool to increase functional capacity in children and adolescents with cystic fibrosis. Copyright © 2014 Elsevier Ltd. All rights reserved.

  16. Modelling Pasture-based Automatic Milking System Herds: System Fitness of Grazeable Home-grown Forages, Land Areas and Walking Distances

    Directory of Open Access Journals (Sweden)

    M. R. Islam

    2015-06-01

    Full Text Available To maintain a predominantly pasture-based system, the large herd milked by automatic milking rotary would be required to walk significant distances. Walking distances of greater than 1-km are associated with an increased incidence of undesirably long milking intervals and reduced milk yield. Complementary forages can be incorporated into pasture-based systems to lift total home grown feed in a given area, thus potentially ‘concentrating’ feed closer to the dairy. The aim of this modelling study was to investigate the total land area required and associated walking distance for large automatic milking system (AMS herds when incorporating complementary forage rotations (CFR into the system. Thirty-six scenarios consisting of 3 AMS herds (400, 600, 800 cows, 2 levels of pasture utilisation (current AMS utilisation of 15.0 t dry matter [DM]/ha, termed as moderate; optimum pasture utilisation of 19.7 t DM/ha, termed as high and 6 rates of replacement of each of these pastures by grazeable CFR (0%, 10%, 20%, 30%, 40%, 50% were investigated. Results showed that AMS cows were required to walk greater than 1-km when the farm area was greater than 86 ha. Insufficient pasture could be produced within a 1 km distance (i.e. 86 ha land with home-grown feed (HGF providing 43%, 29%, and 22% of the metabolisable energy (ME required by 400, 600, and 800 cows, respectively from pastures. Introduction of pasture (moderate: CFR in AMS at a ratio of 80:20 can feed a 400 cow AMS herd, and can supply 42% and 31% of the ME requirements for 600 and 800 cows, respectively with pasture (moderate: CFR at 50:50 levels. In contrast to moderate pasture, 400 cows can be managed on high pasture utilisation (provided 57% of the total ME requirements. However, similar to the scenarios conducted with moderate pasture, there was insufficient feed produced within 1-km distance of the dairy for 600 or 800 cows. An 800 cow herd required 140 and 130 ha on moderate and high pasture

  17. Drug therapy for improving walking distance in intermittent claudication: a systematic review and meta-analysis of robust randomised controlled studies

    DEFF Research Database (Denmark)

    Momsen, A H; Jensen, Martin Bach; Norager, C B

    2009-01-01

    of the databases to February 2009. In addition, reference lists were manually searched. REVIEW METHODS: Based upon a power calculation, only robust (n>56), peer-reviewed, double-blinded, randomised and placebo-controlled trials were included. The main outcomes evaluated were maximal walking distance (MWD) and pain......-free walking distance on a treadmill. Random models were used in the statistical analysis, and chi-square test were used to test for heterogeneity. RESULTS: Among 220 trials, only 43 trials fulfilled the quality criteria. Treatment periods, follow-up and treadmill protocols varied substantially. Vasodilator...... agents and phosphodiesterase inhibitors show robust significant results compared to placebo, but the improvements in MWD are modest. The highest benefit was caused by lipid-lowering agents, which in mean gained above 160 m in MWD, while the other agents only improved MWD about 50 m. CONCLUSION: Several...

  18. Classification and Walking Attractive Distance of BRT Stations%快速公交站点类别及步行吸引范围研究

    Institute of Scientific and Technical Information of China (English)

    朱宏; 谢云侠; 张汝华; 姜洋

    2015-01-01

    Aiming at the simple classification and the rough definition on walking attractive distance of BRT stations, Jinan BRT Line 1 to Line 3 were selected as the research background to make an explora⁃tion on the types of BRT stations and their walking attractive distances. 9 influencing factors were ex⁃tracted basing on the RP Survey of 19 stations and Jinan ArcGIS database. By the use of cluster analysis method and Matlab toolbox, 5 kinds of BRT stations were summarized and their walking attractive dis⁃tances were calculated. The result shows that the attractive distance of walking to the terminal stations is the longest, more than 1 300 meters, followed by that of walking to the transport hub stations with a value of 1 100 meters;the attractive distance of walking to the urban sub-center stations is similar with that of the urban center stations, with an average of 750 meters;for general stations, the attractive distance of walking is the shortest, only about 630 meters. Obviously, there are great differences among walking at⁃tracting distances of different types of stations and a single experience value could not explain all the types. The urban sub-center stations and urban center stations with moderate values are the ideal types.%针对目前对BRT站点简单的分类及步行吸引距离的粗泛定义,以济南市1~3号快速公交作为研究背景,开展了关于快速公交站点分类方法及各类站点对步行吸引范围的研究。以在19个快速公交站点中进行的RP(Revealed Preference Survey)调查及济南ArcGIS数据库为数据基础,选取了9个站点步行吸引距离的影响因素,借助聚类分析法并利用Matlab工具箱拟合正态分布模型,最终总结归纳出5类快速公交站点,并计算得到各类型站点的步行吸引距离。结果表明:终端型站点的步行吸引距离最长,为1300m;其次是交通枢纽型站点,为1100m;城市次中心型与城市中心型站点步行吸引

  19. Repetitive reddish discoloration of urine in a female adolescent following short-distance walking on a smooth road: Questions.

    Science.gov (United States)

    Siomou, Ekaterini; Baziou, Maria; Premetis, Evagelos; Vercellati, Cristina; Chaliasos, Nikolaos; Makis, Alexandros

    2017-02-13

    A previously healthy 15-year-old girl was evaluated following five episodes of reddish urine discoloration after walking for approximately 30 min on a smooth roadway. In each episode, the discoloration lasted for four to five urinations and followed by normal urine dipstick tests. No other exercise-produced urine discoloration and no other symptoms were reported. Laboratory evaluation during the episodes revealed a reddish urine sample with 3+ hemoglobin/myoglobin and absence of hematuria. Full blood count, serum creatinine, liver function tests, and electrolyte levels were all within normal limits. Myoglobulinuria was excluded, since muscle enzymes were within normal limits. Blood smear analysis showed mild anisopoikilocytosis with stomatocytes and ovalocytes, leading to extended evaluation for erythrocyte disorders. This case is interesting in that the hemoglobinuria occurred after mild walking and was accompanied by erythrocyte morphological changes. This quiz discusses the differential diagnosis of hemoglobinuria with particular reference to the conditions of appearance (after walking) and emphasizes the importance of step-by-step investigations to reach a definitive diagnosis.

  20. A cross-sectional study of differences in 6-min walk distance in healthy adults residing at high altitude versus sea level

    Science.gov (United States)

    2014-01-01

    Background We sought to determine if adult residents living at high altitude have developed sufficient adaptation to a hypoxic environment to match the functional capacity of a similar population at sea level. To test this hypothesis, we compared the 6-min walk test distance (6MWD) in 334 residents living at sea level vs. at high altitude. Methods We enrolled 168 healthy adults aged ≥35 years residing at sea level in Lima and 166 individuals residing at 3,825 m above sea level in Puno, Peru. Participants completed a 6-min walk test, answered a sociodemographics and clinical questionnaire, underwent spirometry, and a blood test. Results Average age was 54.0 vs. 53.8 years, 48% vs. 43% were male, average height was 155 vs. 158 cm, average blood oxygen saturation was 98% vs. 90%, and average resting heart rate was 67 vs. 72 beats/min in Lima vs. Puno. In multivariable regression, participants in Puno walked 47.6 m less (95% CI -81.7 to -13.6 m; p < 0.01) than those in Lima. Other variables besides age and height that were associated with 6MWD include change in heart rate (4.0 m per beats/min increase above resting heart rate; p < 0.001) and percent body fat (-1.4 m per % increase; p = 0.02). Conclusions The 6-min walk test predicted a lowered functional capacity among Andean high altitude vs. sea level natives at their altitude of residence, which could be explained by an incomplete adaptation or a protective mechanism favoring neuro- and cardioprotection over psychomotor activity. PMID:24484777

  1. Mortality in active adults age 70-79 years in relation to performance in a long-distance corridor walk.

    Science.gov (United States)

    Singer, Richard B

    2009-01-01

    The authors conducted the source study to determine if a brisk corridor walk of 400 meters could be used to classify the performance of active older adults and relate this performance to mortality and other outcomes over a 6-year follow-up. The cohort consisted of 3075 adults resident in designated ZIP codes in Pittsburgh, Pa, and Memphis, Tenn, participating in the Health Aging and Body Composition Study. Out of this cohort, 395 subjects were excluded after evaluation revealed abnormal vital signs or ECG findings, recent cardiac symptoms, recent surgery, recent chest pain, shortness of breath or fainting. Another 356 subjects were unable to complete the 400-meter walk. The 2324 subjects who completed the walk were divided into quartiles according to the time in seconds required for completion (the overall time required ranged widely from 201 to 942 seconds). These 3 groups were designated as "excluded," "stopped," and "completed." Outcomes reported for the 3075 subjects in the total cohort included mortality, new cardiovascular disease events, mobility limitation, and mobility disability. Cardiovascular events were reported for the 2234 subjects (73% of the total) who were free of cardiovascular disease at entry. Results in the article were given in tables and figures and included numbers of entrants, exposures, and events, annual event rates and hazard ratios with SDs. Out of the 3075 entrant subjects, 430 died in the 6 years of follow-up (FU). Excess mortality measured as excess death rate (EDR) was much higher in the excluded and stopped groups (about 22 per 1000 per year) compared with an EDR of 6.4 per 1000 in the completed group. The corresponding mortality ratios (MR), designated as a hazard ratio in the article were about 220% and 135%. Results for comparative morbidity are also given in this abstract.

  2. Walking, cycling and the urban form: A Heckman selection model of active travel mode and distance by young adolescents

    DEFF Research Database (Denmark)

    Kaplan, Sigal; Nielsen, Thomas Alexander Sick; Prato, Carlo Giacomo

    2016-01-01

    environments for walking and cycling, as the former relates to "street-buffer" urban form measures and the latter also to "transport-zone " ones. Results also show that lessening the amount and the density of car traffic, diminishing the movement of heavy vehicles in local streets, reducing the conflict points...... with the density of intersections, and intervening on crash frequency and severity, would increase the probability and the amount of active travel by young adolescents. Last, results indicate that zones in rural areas and at a higher percentage of immigrants are likely to have lower probability and amount...

  3. Percepção de distância em crianças durante a locomoção Distance perception in children while walking

    Directory of Open Access Journals (Sweden)

    Eliane Mauerberg-deCastro

    2002-01-01

    Full Text Available O objetivo do presente estudo foi investigar a percepção de crianças sobre distância na ausência de informação visual durante a locomoção. Ainda, se parâmetros biomecânicos relativos à locomoção são alterados durante a locomoção nas diferentes distâncias. Sete crianças na idade de 6 anos (GC e 10 adultos (GA foram convidados a andar vendados até alvos pré-estabelecidos. O expoente da função de potência e parâmetros biomecânicos (Ex.: duração da passada, proporção da passada e velocidade da passada foram obtidos para cada grupo. Diferenças foram encontradas somente para os valores de distância produzida ao longo das distâncias testadas. Nenhum dos parâmetros biomecânicos diferiu entre GC e GA. Alterações quantitativas foram observadas nos parâmetros biomecânicos para distâncias curtas, embora o padrão do movimento não tenha sido alterado. Crianças desta faixa etária demonstram, em tarefas não usuais (Ex.: locomoção sem visão, adaptabilidade e capacidade de orientar-se no espaço utilizando apenas da sensibilidade háptica e provavelmente da imagem mental-construída da observação feita antes da realização da tarefa sem informação visual.The purpose of this study was to investigate children's distance perception while walking blindfolded. Also, in order to measure differences at various distances, biomechanical parameters were assessed. Seven children, aged 6 (CG, and 10 adults (AG were asked to walk to previously seen targets placed at different distances. Exponent and biomechanical parameters (i.e., stride duration, stride proportion, and stride velocity were calculated for each group. The CG and AG exhibited similarities in biomechanical parameters, which for both groups changed with the length of the distance. We concluded that both children and adults used similar strategies to accomplish the distance perception task; that locomotion at short distances requires adaptations in gait patterns

  4. Body composition, muscle strength and quality of active elderly women according to the distance covered in the 6-minute walk test

    Directory of Open Access Journals (Sweden)

    Karla H. C. Vilaca

    2013-06-01

    Full Text Available BACKGROUND: Changes arising from the aging process, particularly changes in body composition, contribute to the functional decline of the elderly. OBJECTIVE: To compare the body composition and muscle strength, mobility and quality in active elderly women according to the distance walked during the 6-minute walk test (6MWT. METHOD: The study included 77 active elderly women aged 65 to 80 years, who were divided into tertiles (A, B and C according to the distance covered in the 6MWT. We performed anthropometric and clinical evaluations. Body composition was determined by dual energy X-ray absorptiometry (DXA. Handgrip strength (HGS was measured with a portable dynamometer (Saehan, and knee extension strength (KES was measured with the one repetition maximum test (1-RM. Functional mobility was assessed by the Timed Up and Go (TUG test, and body balance was assessed by the Berg Balance Scale (BBS. Muscle quality was defined by the ratio between muscle strength (kgf and muscle mass (kg. RESULTS: The group that walked the shortest distance in the 6MWT had a higher BMI (A=30.8±7.0, B=27.2±4.2 and C=25.9±3.5 kg/m2, greater amount of fat mass (A=31.3±10.7, B=25.9±6.7 and C=23.81±6.46 kg lower HGS (A=21.8±5.1, B=22.1±3.5 and C=25.5±5.1 kgf, lower knee extension strength (A=30.6±10.9, B=40.4±12.5 and C=47.2±10.1 kgf, lower arm muscle quality (A=10.1±3.7, B=11.6±2 and C=12.7±2.2 kg and lower leg muscle quality (A=1.78±1, B=2.84±0.98 and C=3.31±0.77 kg. There was no significant difference between muscle mass (p=0.25 and lean mass (p=0.26. CONCLUSION: Body fat has a negative influence on functional performance, even among active elderly women.

  5. Six-Minute Walking Distance Correlated with Memory and Brain Volume in Older Adults with Mild Cognitive Impairment: A Voxel-Based Morphometry Study

    Directory of Open Access Journals (Sweden)

    Hyuma Makizako

    2013-08-01

    Full Text Available Background/Aims: High fitness levels play an important role in maintaining memory function and delaying the progression of structural brain changes in older people at risk of developing dementia. However, it is unclear which specific regions of the brain volume are associated with exercise capacity. We investigated whether exercise capacity, determined by a 6-min walking distance (6MWD, is associated with measures of logical and visual memory and where gray matter regions correlate with exercise capacity in older adults with mild cognitive impairment (MCI. Methods: Ninety-one community-dwelling older adults with MCI completed a 6-min walking test, structural magnetic resonance imaging scanning, and memory tests. The Wechsler Memory Scale-Revised Logical Memory and Rey-Osterrieth Complex Figure Tests were used to assess logical and visual memory, respectively. Results: The logical and visual memory tests were positively correlated with the 6MWD (p Conclusions: These results suggest that a better 6MWD performance may be related to better memory function and the maintenance of gray matter volume in older adults with MCI.

  6. Changes in derived measures from six-minute walk distance following home-based exercise training in congestive heart failure: A preliminary report.

    Science.gov (United States)

    Babu, Abraham Samuel; Desai, Charmie V; Maiya, Arun G; Guddattu, Vasudeva; Padmakumar, Ramachandran

    2016-01-01

    The response of derived parameters from six-minute walk distance (6MWD), like 6MW work (6MWW), to exercise training and its correlation with quality of life (QoL) in congestive heart failure (CHF) is not known. A secondary analysis from a randomized controlled trial on 30 patients (23 males; mean age 57.7±10.4 years; mean ejection fraction 31±10%) with CHF in NYHA class I-IV who completed an eight-week home-based exercise training program found a significant improvement in 6MWW (p<0.05), with similar correlations between 6MWD and 6MWW with QoL. 6MWW does not appear to provide additional benefit to 6MWD in cardiac rehabilitation for CHF.

  7. Evaluation of the Effects of Mesoglycan on Some Markers of Endothelial Damage and Walking Distance in Diabetic Patients with Peripheral Arterial Disease

    Science.gov (United States)

    Giuseppe, Derosa; Angela, D’Angelo; Romano, Davide; Pamela, Maffioli

    2017-01-01

    The aim of this study was to evaluate the variation of some parameters involved in peripheral artery disease progression in diabetic patients with peripheral artery disease after six months of mesoglycan. We enrolled 64 Caucasian, type 2 diabetic patients, with stage IIa peripheral artery disease. They were randomized to mesoglycan (Prisma®), 50 mg twice a day, or placebo, for six months. We evaluated: glycemic control, metalloproteinase-2, and -9 (MMP-2, and -9), soluble intercellular adhesion molecule-1 (sICAM-1), soluble vascular cell adhesion protein-1 (sVCAM-1), interleukin-6 (IL-6), soluble E-selectin (sE-selectin), high sensitivity C-reactive protein (hs-CRP), tumor necrosis factor-α (TNF-α), and plasminogen activator inhibitor-1 (PAI-1). We recorded a decrease of MMP-2, MMP-9, sE-selectin, TNF-α, sVCAM-1, and IL-6 compared to baseline, and to placebo in the group treated with mesoglycan. Regarding sICAM-1, and hs-CRP, instead, we recorded a decrease with mesoglycan only compared to baseline. Preliminary results seem to suggest an improvement of pain free walking distance with mesoglycan in 18 patients both compared to baseline and to placebo, even if data should be taken cautiously. Our study showed that supplementation with mesoglycan improved endothelial dysfunction in type 2 diabetic patients with peripheral artery disease. Regarding the preliminary data suggesting also a slight improvement of clinical parameters such as pain free walking distance, more data and a bigger sample of patients are necessary to better verify this aspect. PMID:28272312

  8. Evaluation of the Effects of Mesoglycan on Some Markers of Endothelial Damage and Walking Distance in Diabetic Patients with Peripheral Arterial Disease

    Directory of Open Access Journals (Sweden)

    Derosa Giuseppe

    2017-03-01

    Full Text Available The aim of this study was to evaluate the variation of some parameters involved in peripheral artery disease progression in diabetic patients with peripheral artery disease after six months of mesoglycan. We enrolled 64 Caucasian, type 2 diabetic patients, with stage IIa peripheral artery disease. They were randomized to mesoglycan (Prisma®, 50 mg twice a day, or placebo, for six months. We evaluated: glycemic control, metalloproteinase-2, and -9 (MMP-2, and -9, soluble intercellular adhesion molecule-1 (sICAM-1, soluble vascular cell adhesion protein-1 (sVCAM-1, interleukin-6 (IL-6, soluble E-selectin (sE-selectin, high sensitivity C-reactive protein (hs-CRP, tumor necrosis factor-α (TNF-α, and plasminogen activator inhibitor-1 (PAI-1. We recorded a decrease of MMP-2, MMP-9, sE-selectin, TNF-α, sVCAM-1, and IL-6 compared to baseline, and to placebo in the group treated with mesoglycan. Regarding sICAM-1, and hs-CRP, instead, we recorded a decrease with mesoglycan only compared to baseline. Preliminary results seem to suggest an improvement of pain free walking distance with mesoglycan in 18 patients both compared to baseline and to placebo, even if data should be taken cautiously. Our study showed that supplementation with mesoglycan improved endothelial dysfunction in type 2 diabetic patients with peripheral artery disease. Regarding the preliminary data suggesting also a slight improvement of clinical parameters such as pain free walking distance, more data and a bigger sample of patients are necessary to better verify this aspect.

  9. Crossover from random walk to self-avoiding walk

    Science.gov (United States)

    Rieger, Jens

    1988-11-01

    A one-dimensional n-step random walk on openZ1 which must not visit a vertex more than k times is studied via Monte Carlo methods. The dependences of the mean-square end-to-end distance of the walk and of the fraction of trapped walks on λ=(k-1)/n will be given for the range from λ=0 (self-avoiding walk) to λ=1 (unrestricted random walk). From the results it is conjectured that in the limit n-->∞ the walk obeys simple random walk statistics with respect to its static properties for all λ>0.

  10. Effects of iloprost on pain-free walking distance and clinical outcome in patients with severe stage IIb peripheral arterial disease: the FADOI 2bPILOT Study.

    Science.gov (United States)

    Mazzone, Antonino; Di Salvo, Michelangelo; Mazzuca, Salvatore; Valerio, Antonella; Gussoni, Gualberto; Bonizzoni, Erminio; Campanini, Mauro; Vescovo, Giorgio; Nozzoli, Carlo

    2013-11-01

    Patients with peripheral arterial disease (PAD) at stage IIb, pain-free walking distance (PFWD) less than 100 m and unsuitable for revascularization have both impaired quality of life and severe clinical outcome. Aim of the study was to evaluate the efficacy of the prostacyclin analogue iloprost, added to standard therapy, in these patients. Patients were randomized to receive standard medical therapy (Group A) or standard therapy plus iloprost (Group B), for 1 year. Iloprost was administered for 10 days every 3 months. Treadmill test was performed every 3 months, in Group B before starting the 10-day iloprost cycle. Fifty patients in Group A and 51 in Group B were enrolled. Mean baseline and 12-month PFWD values were 75.4 ± 21.3 and 128.9 ± 62.9 for iloprost group and 70.3 ± 21.6 and 99.6 ± 62.6 m for controls. Patients treated with iloprost had significantly higher PFWD at 9 and 12 months. This finding was confirmed after carrying forward the last valid observation (124.7 ± 63.4 vs. 88.4 ± 63.1 m, P iloprost. Iloprost, added to standard therapy, significantly increases exercise capacity in patients with PAD at severe stage IIb. The percentage of patients who died or experienced major cardiovascular events was significantly lower in patients receiving iloprost. Future studies should focus on the effects of this therapy on clinical outcome. © 2013 Stichting European Society for Clinical Investigation Journal Foundation. Published by John Wiley & Sons Ltd.

  11. k-Walk-Regular Digraphs

    Institute of Scientific and Technical Information of China (English)

    Wen LIU; Jing LIN

    2011-01-01

    In this paper,we define a class of strongly connected digraph,called the k-walk-regular digraph,study some properties of it,provide its some algebraic characterization and point out that the O-walk-regular digraph is the same as the walk-regular digraph discussed BY Liu and Lin in 2010 and the D-walk-regular digraph is identical with the weakly distance-regular digraph defined by Comellas et al in 2004.

  12. The mediating role of cytokine IL-6 on the relationship of FEV1 upon 6-minute walk distance in chronic obstructive pulmonary disease

    Directory of Open Access Journals (Sweden)

    Baldi S

    2014-10-01

    Full Text Available Simonetta Baldi,1 Paul E Jose,2 Claudio Bruschi,1 Gian Domenico Pinna,3 Roberto Maestri,3 Antonella Rezzani,1 Ezio Bellinzona,1 Claudio Fracchia,1 Elena Dacosto,1 Paola Crotti,1 Silvia Montemartini1 1Department of Pneumology, Scientific Institute of Montescano, Salvatore Maugeri Foundation IRCCS, Montescano, Pavia, Italy; 2School of Psychology, Victoria University, Wellington, New Zealand; 3Department of Biomedical Engineering, Scientific Institute of Montescano, Salvatore Maugeri Foundation IRCCS, Montescano, Pavia, ItalyObjectives: To explore the mediating role of protein interleukin-6 (IL-6 on the relationship between forced expiratory volume in 1 second (FEV1 and 6-minute walk distance (6MWD and, further, to determine whether status variables (such as age, sex, and body mass index [BMI] operate as moderators of this mediation relationship.Design: Moderated mediation model.Setting: An inpatient pulmonary rehabilitation center in Italy.Participants: All 153 patients involved in the screening of a randomized controlled clinical trial (ClinicalTrials.gov identifier: NCT01253941 were included in this study. All patients were Global initiative for chronic Obstructive Lung Disease (GOLD stages I–IV and were aged 70.1±9.1 years.Measurements: At run-in phase of the protocol, clinical and functional screening included BMI, fasting plasma levels of protein (IL-6, spirometry, and standardized 6-minute walking test, measured at the start of the respiratory rehabilitation program.Methods: The size of the indirect effect of the initial variable (FEV1 upon the outcome variable (6MWD through the intervening variable (IL-6 was computed and tested for statistical significance. Moderated mediation analyses were subsequently conducted with age, sex, and BMI.Results: FEV1 averaged 53.4%±21.2%, and 6MWD 66.4%±41.3% of predicted. Median protein IL-6 was 6.68 pg/mL (interquartile range: 5.96. A bootstrapped mediation test supported the predicted indirect

  13. Walking abnormalities

    Science.gov (United States)

    ... safety reasons, especially on uneven ground. See a physical therapist for exercise therapy and walking retraining. For a ... the right position for standing and walking. A physical therapist can supply these and provide exercise therapy, if ...

  14. A combined exercise model for ‎improving muscle strength, balance, ‎walking distance, and motor agility ‎in multiple sclerosis patients: A ‎randomized clinical trial

    Directory of Open Access Journals (Sweden)

    Bahram Sangelaji

    2016-08-01

    Full Text Available Background: Multiple sclerosis (MS is a neurological disease with a variety of signs and symptoms. Exercise therapy has been shown to improve physical functions in MS. However, questions about an optimal exercise therapy remain. In this regard, we suggest a combined exercise therapy including aerobic and resistance exercises for MS patients. The study is designed to observe, test and compare the effects of proposed combined exercises on strength, balance, agility, fatigue, speed, and walking distance in people with mild to moderate MS [0 < expanded disability status scale (EDSS < 5].Methods: A total of 40 people with relapse-remitting MS (16 male, 0 < EDSS < 5 were randomized into one of the four groups (3 intervention and one control. The intervention consisted of various combinations of aerobic and resistance exercises with different repetition rates. Pre- and post-intervention scores of fatigue severity scale (FSS, timed up and go (TUG test, 6-minute walk test (6MWT, 10- and 20-MWT, Berg balance scale (BBS, and one repetition maximum (1RM test were recorded and analyzed.Results: For most tests, post-intervention values of the group 1, with 3-aerobic and 1-resistance exercises, were significantly higher compared to control group (P < 0.050. However, no significant progression was observed in the other two intervention groups.Conclusion: A combination of three aerobic exercises with one resistance exercise may result in improved balance, locomotion, and endurance in MS patients.

  15. Six-minute walking distance improvement after pulmonary rehabilitation is associated with baseline lung function in complex COPD patients: a retrospective study.

    Science.gov (United States)

    Zanini, Andrea; Chetta, Alfredo; Gumiero, Federico; Della Patrona, Sabrina; Casale, Silvia; Zampogna, Elisabetta; Aiello, Marina; Spanevello, Antonio

    2013-01-01

    Conflicting results have been so far reported about baseline lung function, as predicting factor of pulmonary rehabilitation (PR) efficacy. To ascertain whether or not baseline lung function could predict a benefit in terms of a significant change in 6-min walk test (6 MWT) after PR. Seventy-five stable moderate-to-severe COPD inpatients with comorbidities (complex COPD), allocated to a three-week PR program, were retrospectively evaluated. Pulmonary function, 6 MWT, dyspnea (BDI/TDI), and quality of life (EQ-VAS) were assessed before and after PR program. The patients were divided into two groups depending on the change in 6 MWT (responders > 30 m and nonresponders ≤ 30 m). Logistic regression analysis was used. Results. After PR, 6 MWT performance all outcome measures significantly improved (P function (P PR efficacy. Our study shows that in stable moderate-to-severe complex COPD inpatients, baseline lung function may predict the response to PR in terms of 6 MWT. We also found that complex COPD patients with poor lung function get more benefit from PR.

  16. Two- and 6-minute walk tests assess walking capability equally in neuromuscular diseases

    DEFF Research Database (Denmark)

    Andersen, Linda Kahr; Knak, Kirsten Lykke; Witting, Nanna;

    2016-01-01

    to participate on 2 test days, each consisting of 1 2MWT and 1 6MWT separated by a minimum 30-minute period of rest. The order of the walk tests was randomly assigned via sealed envelopes. A group of 38 healthy controls completed 1 6MWT. RESULTS: The mean walking distance for the 2MWT was 142.8 meters......OBJECTIVE: This methodologic study investigates if the 2-minute walk test (2MWT) can be a valid alternative to the 6-minute walk test (6MWT) to describe walking capability in patients with neuromuscular diseases. METHODS: Patients (n = 115) with different neuromuscular diseases were invited...... and for the 6MWT 405.3 meters. The distance walked in the 2MWT was highly correlated to the distance walked in the 6MWT (r = 0.99, p minute in the 6MWT, both among patients and healthy controls, which was not evident in the 2MWT...

  17. Walking Problems

    Science.gov (United States)

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

  18. Walk the line: station context, corridor type and bus rapid transit walk access in Jinan, China

    OpenAIRE

    Jiang, Yang; Mehndiratta, Shomik; Zegras, P. Christopher

    2011-01-01

    This paper examines BRT station walk access patterns in rapidly urbanizing China and the relationship between bus rapid transit (BRT) station context and corridor type and the distance people will walk to access the system (i.e., catchment area). We hypothesize that certain contextual built environment features and station and right-of-way configurations will increase the walk-access catchment area; that is, that urban design influences users’ willingness to walk to BRT. We base our analysis ...

  19. 步行距离、港铁出行意愿与站域范围的关联研究%Research on Relationship of Catchment Area, MTR Riding Intent and Walking Distance in Hong Kong

    Institute of Scientific and Technical Information of China (English)

    殷子渊

    2016-01-01

    如何确定轨道站影响范围(站域)是研究轨道与城市空间问题的基础,该问题涉及居民步行距离与轨道乘坐意愿的关系。距离是影响人们步行出行的重要因素,影响公共基础设施的服务范围。目前针对步行距离因素如何影响居民轨道通勤出行意愿的定量研究尚少,这种局面对于定量理解轨道站的影响范围(站域)非常不利。基于725栋香港居住建筑轨道通勤出行意愿调查结果的研究,运用了指数距离衰减模型对香港居民步行距离和轨道乘坐意愿进行关联分析,通过比对不同距离区间衰减系数‘β’的变化趋势,分析了真实步行距离如何影响港铁通勤出行的意愿和距离阈值空间。步行距离阈值范围的研究为分级确定轨道站影响区域提供了定量的依据;使用绕路系数指标可以评价站域空间结构,并为轨道站周边空间的建设与整合提供量化依据。%Catchment area is one of crucial issues in research of transit system and urban space. Based on survey of MTR commuting travel rate in Hong Kong, this research employed exponent distance decay model to analyze on how distance impact on metro riding intent. Based on surveys of MTR commuting rate from 725 residential buildings, the ranges of thresholds can be concluded where distance impacting on riding intent intensively through comparative study of the measuring of decay coefficient, whereby the catchment area of metro station can be defined quantitatively by factors as detour rate and walking distance.

  20. The benefit of pulmonary rehabilitation against quality of life alteration and functional capacity of chronic obstructive pulmonary disease patient assessed using St George’s respiratory questionnaire and 6 minutes walking distance test

    Directory of Open Access Journals (Sweden)

    Wiwien H. Wiyono

    2006-09-01

    Full Text Available Patients with chronic obstructive pulmonary disease (COPD have been shown to be benefit from pulmonary rehabilitation programs. We assessed an entirely outpatient-based program of pulmonary rehabilitation in patients with COPD, using the St George’s Respiratory Questionnaire (SGRQ and six minutes walking distance test (6MWD (which measures health-related quality of life and functional exercise tolerance as the primary outcome measure. We undertook a randomized, opened, prospective, parallel-group controlled study of outpatient rehabilitation program in 56 patients with COPD (52 men and 4 women. The active group (n=27 took part in a 6-weeks program of education and exercise. The control group (n=29 were reviewed routinely as medical outpatients. The SGRQ and 6MWD were administered at study entry and after 6 weeks. Outcome with SGRQ and 6MWD before and after therapy was performed. Decrease score SGRQ and increase 6MWD in both groups of study, it was analyzed by statistic study and in active group the decrease of SGRQ and the increase of 6MWD was statistically significant. In conclusion 6-weeks outpatient-based program significantly improved quality of life and functional capacity in mild-to-moderate COPD patient. (Med J Indones 2006; 15:165-72 Keywords: COPD, pulmonary rehabilitation, SGRQ, 6MWD

  1. Differences in walking pattern during 6-min walk test between patients with COPD and healthy subjects.

    Directory of Open Access Journals (Sweden)

    Janneke Annegarn

    Full Text Available 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.

  2. Representing distance, consuming distance

    DEFF Research Database (Denmark)

    Larsen, Gunvor Riber

    to mobility and its social context. Such an understanding can be approached through representations, as distance is being represented in various ways, most noticeably in maps and through the notions of space and Otherness. The question this talk subsequently asks is whether these representations of distance...... are being consumed in the contemporary society, in the same way as places, media, cultures and status are being consumed (Urry 1995, Featherstone 2007). An exploration of distance and its representations through contemporary consumption theory could expose what role distance plays in forming...... are present in theoretical and empirical elaborations on mobility, but these remain largely implicit and unchallenged (Bauman 1998). This talk will endeavour to unmask distance as a theoretical entity by exploring ways in which distance can be understood and by discussing distance through its representations...

  3. Random walk near the surface

    Science.gov (United States)

    Korneta, W.; Pytel, Z.

    1988-07-01

    The random walk of a particle on a three-dimensional semi-infinite lattice is considered. In order to study the effect of the surface on the random walk, it is assumed that the velocity of the particle depends on the distance to the surface. Moreover it is assumed that at any point the particle may be absorbed with a certain probability. The probability of the return of the particle to the starting point and the average time of eventual return are calculated. The dependence of these quantities on the distance to the surface, the probability of absorption and the properties of the surface is discussed. The method of generating functions is used.

  4. The Walk Poem.

    Science.gov (United States)

    Padgett, Ron

    2000-01-01

    Discusses the long history of writing poems about a walk, noting many titles. Notes four basic types of walk poems and includes one by American poet Bill Zavatksy, called "Class Walk With Notebooks After Storm." Offers numerous brief ideas for both the writing and the form of walk poems. (SR)

  5. Walking, places and wellbeing

    NARCIS (Netherlands)

    Ettema, Dick; Smajic, Ifeta

    2015-01-01

    While there is a substantial body of research on the health implications of walking, the physical, emotional and social outcomes of walking have received limited attention. This paper explores the wellbeing effects of walking and how the walking environment fosters or hinders such wellbeing effects.

  6. Walking, places and wellbeing

    NARCIS (Netherlands)

    Ettema, Dick; Smajic, Ifeta

    2015-01-01

    While there is a substantial body of research on the health implications of walking, the physical, emotional and social outcomes of walking have received limited attention. This paper explores the wellbeing effects of walking and how the walking environment fosters or hinders such wellbeing effects.

  7. Accelerometry-enabled measurement of walking performance with a robotic exoskeleton: a pilot study

    National Research Council Canada - National Science Library

    Lonini, Luca; Shawen, Nicholas; Scanlan, Kathleen; Rymer, William Z; Kording, Konrad P; Jayaraman, Arun

    2016-01-01

    Clinical scores for evaluating walking skills with lower limb exoskeletons are often based on a single variable, such as distance walked or speed, even in cases where a host of features are measured...

  8. Fire-Walking

    Science.gov (United States)

    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…

  9. Fire-Walking

    Science.gov (United States)

    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…

  10. Effects of walking trainings on walking function among stroke survivors: a systematic review.

    Science.gov (United States)

    Ilunga Tshiswaka, Daudet; Bennett, Crystal; Franklin, Cheyanne

    2017-08-29

    Physical function is often compromised as a result of stroke event. Although interventions propose different strategies that seek to improve stroke survivors' physical function, a need remains to evaluate walking training studies aimed at improving such physical function. The aim of this review was to assess the available literature that highlights the impact of walking training on enhancing walking for stroke survivors. We performed a systematic literature review of online databases - Google Scholar, PubMed, CINHAL, Cochrane Library, Scopus, and EBSCO - with the following inclusion criteria: manuscript published from 2005 to 2016, written in English, with treatment and control groups, for walking training studies aimed at improving physical function among stroke survivors. Findings indicated that walking speed, walking distance, and gait speed were the most used outcome variables for measuring improved physical function among stroke survivors. Importantly, proposed interventions involved either overground or treadmill walking trainings, if not both. Preserved locomotor improvements were not noted in all interventions at follow-up. Some interventions that used walking treadmill training augmented by auditory stimulations reported significant improvements in physical function compared with overground walking training augmented by auditory stimulations. The imperative to improve physical function among stroke survivors with physical impairment is paramount, as it allows survivors to be socially, emotionally, and physically more independent. In general, we note an insufficiency of research on the interaction between physical function and socialization among stroke survivors.

  11. On alternating quantum walks

    Science.gov (United States)

    Rousseva, Jenia; Kovchegov, Yevgeniy

    2017-03-01

    We study an inhomogeneous quantum walk on a line that evolves according to alternating coins, each a rotation matrix. For the quantum walk with the coin alternating between clockwise and counterclockwise rotations by the same angle, we derive a closed form solution for the propagation of probabilities, and provide its asymptotic approximation via the method of stationary phase. Finally, we observe that for a x03c0;/4 angle, this alternating rotation walk will replicate the renown Hadamard walk.

  12. The work of walking: a calorimetric study.

    Science.gov (United States)

    Webb, P; Saris, W H; Schoffelen, P F; Van Ingen Schenau, G J; Ten Hoor, F

    1988-08-01

    Experiments were designed to test the traditional assumption that during level walking all of the energy from oxidation of fuel appears as heat and no work is done. Work is force expressed through distance, or energy transferred from a man to the environment, but not as heat. While wearing a suit calorimeter in a respiration chamber, five women and five men walked for 70 to 90 min on a level treadmill at 2.5, 4.6, and 6.7 km.h-1 and pedalled a cycle ergometer for 70 to 90 min against 53 and 92 W loads. They also walked with a weighted backpack and against a horizontal load. During cycling, energy from fuel matched heat loss plus the power measured by the ergometer. During walking, however, energy from fuel exceeded that which appeared as heat, meaning that work was done. The power increased with walking speed; values were 14, 29, and 63 W, which represented 11, 12, and 13% of the incremental cost of fuel above the resting level. Vertical and horizontal loads increased the fuel cost and heat loss of walking but did not alter the power output. This work energy did not re-appear as thermal energy during 18 h of recovery. The most likely explanation of the work done is in the inter-action between the foot and the ground, such as compressing the heel of the shoe and bending the sole. We conclude that work is done in level walking.

  13. Disaggregate land uses and walking.

    Science.gov (United States)

    McConville, Megan E; Rodríguez, Daniel A; Clifton, Kelly; Cho, Gihyoug; Fleischhacker, Sheila

    2011-01-01

    Although researchers have explored associations between mixed-use development and physical activity, few have examined the influence of specific land uses. This study analyzes how the accessibility, intensity, and diversity of nonresidential land uses are related to walking for transportation. Multinomial logistic regression was used to investigate associations between walking for transportation and neighborhood land uses in a choice-based sample of individuals (n=260) in Montgomery County MD. Land uses examined included banks, bus stops, fast-food restaurants, grocery stores, libraries, rail stations, offices, parks, recreation centers, non-fast-food restaurants, retail, schools, sports facilities, night uses, physical activity uses, and social uses. Exposure to these uses was measured as the street distance from participants' homes to the closest instance of each land use (accessibility); the number of instances of each land use (intensity); and the number of different land uses (diversity). Data were collected from 2004-2006 and analyzed in 2009-2010. After adjusting for individual-level characteristics, the distances to banks, bus stops, fast-food restaurants, grocery stores, rail stations, physical activity uses, recreational facilities, restaurants, social uses and sports facilities were associated negatively with transportation walking (ORs [95% CI] range from 0.01 [0.001, 0.11] to 0.91 [0.85, 0.97]). The intensities of bus stops, grocery stores, offices, and retail stores in participants' neighborhoods were associated positively with transportation walking (ORs [95% CI] range from 1.05 [1.01, 1.08] to 5.42 [1.73, 17.01]). Land-use diversity also was associated positively with walking for transportation (ORs [95% CI] range from 1.39 [1.20, 1.59] to 1.69 [1.30, 2.20]). The accessibility and intensity of certain nonresidential land uses, along with land-use diversity, are positively associated with walking for transportation. A careful mix of land uses in a

  14. Iterated random walks with shape prior

    DEFF Research Database (Denmark)

    Pujadas, Esmeralda Ruiz; Kjer, Hans Martin; Piella, Gemma;

    2016-01-01

    We propose a new framework for image segmentation using random walks where a distance shape prior is combined with a region term. The shape prior is weighted by a confidence map to reduce the influence of the prior in high gradient areas and the region term is computed with k-means to estimate th...

  15. Assessment of a Solar System Walk

    Science.gov (United States)

    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…

  16. Assessment of a Solar System Walk

    Science.gov (United States)

    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…

  17. Six-minute-walk test in chronic obstructive pulmonary disease

    DEFF Research Database (Denmark)

    Polkey, Michael I; Spruit, Martijn A; Edwards, Lisa D

    2013-01-01

    Outcomes other than spirometry are required to assess nonbronchodilator therapies for chronic obstructive pulmonary disease. Estimates of the minimal clinically important difference for the 6-minute-walk distance (6MWD) have been derived from narrow cohorts using nonblinded intervention.......Outcomes other than spirometry are required to assess nonbronchodilator therapies for chronic obstructive pulmonary disease. Estimates of the minimal clinically important difference for the 6-minute-walk distance (6MWD) have been derived from narrow cohorts using nonblinded intervention....

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

    Science.gov (United States)

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

    2004-09-01

    To evaluate the immediate and long-term effects of aerobic treadmill plus Bobath walking training in subacute stroke survivors compared with Bobath walking training alone. Randomized controlled trial. Rehabilitation unit. Fifty patients, first-time supratentorial stroke, stroke interval less than six weeks, Barthel Index (0-100) from 50 to 80, able to walk a minimum distance of 12 m with either intermittent help or stand-by while walking, cardiovascular stable, minimum 50 W in the bicycle ergometry, randomly allocated to two groups, A and B. Group A 30 min of treadmill training, harness secured and minimally supported according to patients' needs, and 30 min of physiotherapy, every workday for six weeks, speed and inclination of the treadmill were adjusted to achieve a heart rate of HR: (Hrmax-HRrest)*0.6+HRrest; in group B 60 min of daily physiotherapy for six weeks. Primary outcome variables were the absolute improvement of walking velocity (m/s) and capacity (m), secondary were gross motor function including walking ability (score out of 13) and walking quality (score out of 41), blindly assessed before and after the intervention, and at follow-up three months later. Patients tolerated the aerobic training well with no side-effects, significantly greater improvement of walking velocity and capacity both at study end (p =0.001 versus p =0.002) and at follow-up (p Bobath walking training in moderately affected stroke patients was better than Bobath walking training alone with respect to the improvement of walking velocity and capacity. The treatment approach is recommended in patients meeting the inclusion criteria. A multicentre trial should follow to strengthen the evidence.

  19. Reliability of the 6-min walk test after total knee arthroplasty

    DEFF Research Database (Denmark)

    Jakobsen, Thomas Linding; Kehlet, Henrik; Bandholm, Thomas

    2013-01-01

    PURPOSE: The 6-min walk test is a simple clinical outcome measure, which has been used frequently to assess functional performance in many different patient groups, including patients with total knee arthroplasty (TKA). The 6-min walk test measures the maximal distance a subject is able to walk...

  20. Functional electrical stimulation-assisted walking for persons with incomplete spinal injuries

    DEFF Research Database (Denmark)

    Ladouceur, M.; Barbeau, H.

    2000-01-01

    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...

  1. Quantum Walk with Jumps

    CERN Document Server

    Lavička, H; Kiss, T; Lutz, E; Jex, I

    2011-01-01

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

  2. Validity of the Nike+ device during walking and running.

    Science.gov (United States)

    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.

  3. Walking to Work: Trends in the United States, 2005–2014

    Science.gov (United States)

    2016-01-01

    I examined trends from 2005 through 2014 in walking to work compared with other modes of travel. For each year, I calculated the percentage of travel to work by private vehicle, public transportation, and walking and used distance decay functions to analyze the distribution of walking by distance. I found that the percentage of travel to work by walking remained stable, with a slight increase over time, and that people tended to walk longer to get to work. The trend is positive and encouraging, although more evidence is needed to confirm my findings. PMID:27657507

  4. Does the six-minute walk test measure walking performance or physical fitness in persons with multiple sclerosis?

    Science.gov (United States)

    Sandroff, Brian M; Pilutti, Lara A; Motl, Robert W

    2015-01-01

    There is psychometric evidence that supports the six-minute walk (6MW) as a measure of walking performance, whereas other psychometric data support it as a submaximal measure of physical fitness in persons with MS. The current cross-sectional study compared measures of walking performance and physical fitness as head-to-head predictors of 6MW distance in a sample of persons with MS across the disability spectrum. All participants completed the 6MW test, as well as other measures of walking performance (i.e., timed-25 foot walk, gait velocity captured by a GaitRite electronic walkway) and physical fitness (i.e., peak aerobic capacity, lower limb muscular strength). 6MW distance was strongly associated with measures of walking performance and physical fitness, though the correlations were significantly stronger for measures of walking performance than physical fitness (z >  4.04, p   0.85), and measures of physical fitness explained minimal variance in 6MW distance over-and-above that of measures of walking performance (ΔR2 fitness in MS.

  5. Quantum Walk on a Line with Two Entangled Particles

    CERN Document Server

    Omar, Y; Sheridan, L; Bose, S

    2004-01-01

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

  6. Periodic sound-based 6-minute walk test forpatients with Duchenne muscular dystrophy:a preliminary study

    Science.gov (United States)

    Nishizawa, Hitomi; Genno, Hirokazu; Shiba, Naoko; Nakamura, Akinori

    2015-01-01

    [Purpose] The purpose of this study was to verify if a periodic sound-based 6-minute walk test with the best periodic sound could be used to evaluate physical endurance more precisely than the conventional 6-minute walk test. [Subjects] The subjects were healthy subjects and 6 ambulant patients with Duchenne muscular dystrophy. [Methods] The subjects initially walked for 1 minute to a long-interval metronome sound, and the walking distance was measured. The sound interval was then gradually shortened, and the subjects walked for 1 minute for each of the intervals. The best periodic sound was considered to be the periodic sound used when the subject walked the longest distance in 1 minute, and the process of determining it was referred to as the period shortening walk test. This study administered the 6-minute walk test with the best periodic sound to twenty healthy subjects and 6 ambulant patients with Duchenne muscular dystrophy and compared the walking distance. [Results] The periodic sound-based 6-minute walk test distances in both the healthy subjects and the patients were significantly longer than the conventional 6-minute walk test distances. [Conclusion] The periodic sound-based 6-minute walk test provided a better indication of ambulatory potential in an evaluation of physical endurance than the conventional 6-minute walk test. PMID:26696721

  7. Distance Learning

    Science.gov (United States)

    1997-12-01

    A study reviewing the existing Army Distance Learning Plan (ADLP) and current Distance Learning practices, with a focus on the Army’s training and...educational challenges and the benefits of applying Distance Learning techniques. The ASB study panel makes six specific recommendations, the most

  8. Walks on Weighted Networks

    Institute of Scientific and Technical Information of China (English)

    WU An-Cai; XU Xin-Jian; WU Zhi-Xi; WANG Ying-Hai

    2007-01-01

    We investigate the dynamics of random walks on weighted networks. Assuming that the edge weight and the node strength are used as local information by a random walker. Two kinds of walks, weight-dependent walk and strength-dependent walk, are studied. Exact expressions for stationary distribution and average return time are derived and confirmed by computer simulations. The distribution of average return time and the mean-square that a weight-dependent walker can arrive at a new territory more easily than a strength-dependent one.

  9. Virtually Abelian quantum walks

    Science.gov (United States)

    Mauro D'Ariano, Giacomo; Erba, Marco; Perinotti, Paolo; Tosini, Alessandro

    2017-01-01

    We study discrete-time quantum walks on Cayley graphs of non-Abelian groups, focusing on the easiest case of virtually Abelian groups. We present a technique to reduce the quantum walk to an equivalent one on an Abelian group with coin system having larger dimension. This method allows one to extend the notion of wave-vector to the virtually Abelian case and study analytically the walk dynamics. We apply the technique in the case of two quantum walks on virtually Abelian groups with planar Cayley graphs, finding the exact solution in terms of dispersion relation.

  10. On d-Walk Regular Graphs

    OpenAIRE

    Estrada, Ernesto; de la Pena, Jose A.

    2013-01-01

    Let G be a graph with set of vertices 1,...,n and adjacency matrix A of size nxn. Let d(i,j)=d, we say that f_d:N->N is a d-function on G if for every pair of vertices i,j and k>=d, we have a_ij^(k)=f_d(k). If this function f_d exists on G we say that G is d-walk regular. We prove that G is d-walk regular if and only if for every pair of vertices i,j at distance

  11. Random walk term weighting for information retrieval

    DEFF Research Database (Denmark)

    Blanco, R.; Lioma, Christina

    2007-01-01

    We present a way of estimating term weights for Information Retrieval (IR), using term co-occurrence as a measure of dependency between terms.We use the random walk graph-based ranking algorithm on a graph that encodes terms and co-occurrence dependencies in text, from which we derive term weights...... that represent a quantification of how a term contributes to its context. Evaluation on two TREC collections and 350 topics shows that the random walk-based term weights perform at least comparably to the traditional tf-idf term weighting, while they outperform it when the distance between co-occurring terms...

  12. Reduction of the six-minute walk distance in children with sickle cell disease is correlated with silent infarct: results from a cross-sectional evaluation in a single center in Belgium.

    Directory of Open Access Journals (Sweden)

    Laurence Dedeken

    Full Text Available BACKGROUND: The 6-minute walk test (6 MWT is used in adults and children affected by a wide range of chronic diseases to evaluate their sub-maximal exercise capacity. It reflects the global response of various physiological systems in a situation simulating a daily life activity. METHODS: We analyzed factors affecting the 6 MWT in 46 Sickle Cell Disease children. Forty-two were treated with hydroxyurea (HU. Patients with normal test (>80% of the age-standardized predicted value were compared to patients with abnormal test (≤ 80%. Baseline hematological values, clinical events, cerebrovascular disease, cardio-pulmonary parameters and disease-modifying treatment were compared according to the performance of the test. RESULTS: Among the 46 patients, 14 had an abnormal 6 MWT. In univariate analysis, both groups were similar for biological and clinical data. Six of the 14 patients with an abnormal 6 MWT had silent infarct (SI compared to 6/32 with a normal test (P = 0.09. When excluding chronically transfused patients, 4 of the 11 patients with an abnormal 6 MWT had SI compared to 1/26 (P = 0.02. Baseline pulse oximetry was normal in both groups but slightly lower in patients with abnormal 6 MWT (P = 0.02. No patient presented exercise-induced desaturation. In multivariate analysis, the only factor associated with abnormal 6 MWT was the presence of SI (P = 0.045. CONCLUSIONS: In our cohort of 46 patients characterized by high exposure rate to HU and by the absence of severe cardiopulmonary disease, the sole factor independently associated with 6 MWT was the presence of SI. The lower exercise capacity of children with SI may reflect some subclinical neurological impairment as they do not differ by hemoglobin level or cardiopulmonary parameters.

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

    Science.gov (United States)

    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

  14. More Adults Are Walking

    Centers for Disease Control (CDC) Podcasts

    2012-07-31

    This podcast is based on the August 2012 CDC Vital Signs report. While more adults are walking, only half get the recommended amount of physical activity. Listen to learn how communities, employers, and individuals may help increase walking.  Created: 7/31/2012 by Centers for Disease Control and Prevention (CDC).   Date Released: 8/7/2012.

  15. Distances walked in the six-minute walk test: suggestion of defining characteristic for the nursing diagnosis Ineffective Peripheral Tissue Perfusion Distancias recorridas en la prueba de caminata de los seis minutos: propuesta de característica definitoria para el diagnóstico de enfermería Perfusión Tisular Periférica Inefectiva Distâncias percorridas no teste de caminhada de seis minutos: proposta de característica definidora para o diagnóstico de enfermagem Perfusão Tissular Periférica Ineficaz

    Directory of Open Access Journals (Sweden)

    Rita de Cassia Gengo e Silva

    2012-04-01

    Full Text Available Distances walked in walking tests are important functional markers, although they are not accepted as defining characteristics of Ineffective Peripheral Tissue Perfusion. The aims of this study were to verify the distances participants with and without this nursing diagnosis walked in the six-minute walk test and if these measures may be considered defining characteristics of this phenomenon. Participants with (group A; n=65 and without (group B; n=17 this nursing diagnosis were evaluated regarding physical examination, vascular function and functional capacity. Participants of group A seemed to have worse vascular function and functional capacity compared with those of group B. Pain-free travelled distance was predictive of the nursing diagnosis. These results are important for the refinement of this diagnosis. In conclusion, this study provides evidences that the distances walked in the six-minute walk test may be considered defining characteristics of Ineffective Peripheral Tissue Perfusion.Las distancias en pruebas de marcha son importantes marcadores funcionales, pero no son aceptados como características de definición de la Perfusión Tisular Periférica Inefectiva. Los objetivos fueron determinar las distancias recorridas en la prueba de caminata de los seis minutos por los participantes con e sin el diagnóstico de enfermería y si esas medidas se pueden considerar características de definición de este fenómeno. Los participantes con (grupo A, n=65 y sin (grupo B, n=17 el diagnóstico fueron evaluados mediante examen físico, función vascular periférica y capacidad funcional. Los participantes del grupo A ha presentado peor función vascular y desempeño en la prueba de marcha do que aquellos del grupo B. La distancia recorrida libre de dolor fue predictiva del diagnóstico de enfermería. Los resultados de este estudio pueden contribuir para el refinamiento de este diagnóstico. Las distancias recorridas en la prueba de marcha se

  16. How does wearable robotic exoskeleton affect overground walking performance measured with the 10-m and six-minute walk tests after a basic locomotor training in healthy individuals?

    Science.gov (United States)

    Gagnon, Dany H; Cunha, Jérémie Da; Boyer-Delestre, Mael; Bosquet, Laurent; Duclos, Cyril

    2017-08-26

    It is still unknown to what extent overground walking with a WRE is equivalent to natural overground walking without a WRE. Hence, the interpretability of the 10-m (10MWT) and six-minute (6MWT) walk tests during overground walking with a WRE against reference values collected during natural overground walking without a WRE is challenging. This study aimed to 1) compare walking performance across three different overground walking conditions: natural walking without a WRE, walking with a WRE providing minimal assistance (active walking), and walking with a WRE proving complete assistance (passive walking) and 2) assess the association and the agreement between the 10MWT and the 6MWT during passive and active walking with a WRE. Seventeen healthy individuals who underwent basic locomotor training with a WRE performed the 10MWT (preferred and maximal speeds) and the 6MWT under the three conditions. For the 10MWT, the speed progressively and significantly decreased from natural walking without a WRE (preferred: 1.40±0.18m/s; maximal: 2.16±0.19m/s), to active walking with a WRE (preferred: 0.48±0.10m/s; maximal: 0.61±0.14m/s), and to passive walking with a WRE (preferred: 0.38±0.09m/s; maximal: 0.42±0.10m/s). For the 6MWT, total distances decreased from walking without a WRE (609±53.9m), to active walking with a WRE (196.6±42.6m), and to passive walking with a WRE (144.3±33.3m). The 10MWT and 6MWT provide distinct information and can't be used interchangeably to document speed only during active walking with the WRE. Speed and distance drastically decrease during active and, even more so, passive walking with the WRE in comparison to walking without a WRE. Selection of walking tests should depend on the level of assistance provided by the WRE. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Biomechanical analysis of rollator walking

    DEFF Research Database (Denmark)

    Alkjaer, T; Larsen, Peter K; Pedersen, Gitte

    2006-01-01

    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.......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....

  18. 6min步行距离和气短指数在城乡COPD患者中的差异性研究%Study on the difference of six-minute walking distance and short breath index for urban and rural patients with chronic obstructive pulmonary diseases

    Institute of Scientific and Technical Information of China (English)

    朱明兰; 崔伟; 万霞; 黄议; 伍彩红; 邓仁丽

    2012-01-01

    目的 探讨6 min步行距离和气短指数在城乡COPD患者中的差异.方法 2010年6月至2011年10月,处于缓解期肺功能Ⅱ~Ⅳ级COPD患者108例,按照患者来源(农村或城市)分为城市组和农村组,进行6 min步行试验,记录两组患者6 min步行距离及步行前后的气短指数评分.结果 6 min步行距离,Ⅱ、Ⅲ级COPD患者农村组高于城市组(P<0.05);Ⅳ级COPD患者农村组和城市组之间无明显差异(P>0.05).同时,6分钟步行试验前后的气短指数评分,Ⅱ、Ⅲ级COPD患者农村组低于城市组(P<0.05);Ⅳ级COPD患者城市组与农村组之间无明显差异(P>0.05).结论 肺功能Ⅱ~Ⅲ级城乡COPD患者进行6 min步行试验时6 min步行距离和气短指数存在差异,提示COPD患者长期坚持适度体力劳动或运动锻炼有利于提高运动耐力.%Objective To study the difference of six-minute walking distance (6MWD) and short breath index for urban and rural patients with chronic obstructive pulmonary diseases (COPD). Method Divide 108 patients with COPD in remission stage from June 2010 to October 2011 with pulmonary function of Ⅱ ~Ⅳ into urban group and rural group according to their origin region. After six- minute walking test, record their 6MWD and short breath indexes before and after walking. Result 6MWD for patients with COPD with pulmonary function of Ⅱ - Ⅲ in rural group is significantly longer than in urban group (P0. 05). Scores of short breath indexes before and after walking test for patients with COPD with pulmonary function of TT ~ TFT in rural group arc significantly lower than in urban group (P0. 05). Conclusion There is significant difference on 6MWD and short breath index in six-minute walking test between urban and rural patients with COPD with pulmonary function of Ⅱ - Ⅲ. Insisting on long-term moderate manual work or physical exercise can improve exercise tolerance for patients with COPD.

  19. Quantum walks: a comprehensive review

    CERN Document Server

    Venegas-Andraca, Salvador E

    2012-01-01

    Quantum walks, the quantum mechanical counterpart of classical random walks, is an advanced tool for building quantum algorithms that has been recently shown to constitute a universal model of quantum computation. Quantum walks is now a solid field of research of quantum computation full of exciting open problems for physicists, computer scientists, mathematicians and engineers. In this paper we review theoretical advances on the foundations of both discrete- and continuous-time quantum walks, together with the role that randomness plays in quantum walks, the connections between the mathematical models of coined discrete quantum walks and continuous quantum walks, the quantumness of quantum walks, a summary of papers published on discrete quantum walks and entanglement as well as a succinct review of experimental proposals and realizations of discrete-time quantum walks. Furthermore, we have reviewed several algorithms based on both discrete- and continuous-time quantum walks as well as a most important resul...

  20. Scaling Argument of Anisotropic Random Walk

    Institute of Scientific and Technical Information of China (English)

    XU Bing-Zhen; JIN Guo-Jun; WANG Fei-Feng

    2005-01-01

    In this paper, we analytically discuss the scaling properties of the average square end-to-end distance for anisotropic random walk in D-dimensional space ( D ≥ 2), and the returning probability Pn(ro) for the walker into a certain neighborhood of the origin. We will not only give the calculating formula for and Pn (ro), but also point out that if there is a symmetric axis for the distribution of the probability density of a single step displacement, we always obtain ~ n, where ⊥ refers to the projections of the displacement perpendicular to each symmetric axes of the walk; in D-dimensional space with D symmetric axes perpendicular to each other, we always have ~ n and the random walk will be like a purely random motion; if the number of inter-perpendicular symmetric axis is smaller than the dimensions of the space, we must have ~ n2 for very large n and the walk will be like a ballistic motion. It is worth while to point out that unlike the isotropic random walk in one and two dimensions, which is certain to return into the neighborhood of the origin, generally there is only a nonzero probability for the anisotropic random walker in two dimensions to return to the neighborhood.

  1. Information Distance

    CERN Document Server

    Bennett, Charles H; Li, Ming; Vitanyi, Paul M B; Zurek, Wojciech H

    2010-01-01

    While Kolmogorov complexity is the accepted absolute measure of information content in an individual finite object, a similarly absolute notion is needed for the information distance between two individual objects, for example, two pictures. We give several natural definitions of a universal information metric, based on length of shortest programs for either ordinary computations or reversible (dissipationless) computations. It turns out that these definitions are equivalent up to an additive logarithmic term. We show that the information distance is a universal cognitive similarity distance. We investigate the maximal correlation of the shortest programs involved, the maximal uncorrelation of programs (a generalization of the Slepian-Wolf theorem of classical information theory), and the density properties of the discrete metric spaces induced by the information distances. A related distance measures the amount of nonreversibility of a computation. Using the physical theory of reversible computation, we give...

  2. Effect of Salmeterol and Fluticasone Propionate on Cardiopulmonary Function and 6 min Walking Distance in Patients with Severe COPD%沙美特罗替卡松对重度慢性阻塞性肺疾病患者心肺功能及6 min步行距离的影响

    Institute of Scientific and Technical Information of China (English)

    陈斌; 陈琼

    2016-01-01

    目的:探讨沙美特罗替卡松对重度慢性阻塞性肺疾病(COPD)患者心肺功能及6 min步行距离的影响。方法选取2013年3月至2015年5月收治的重度COPD患者100例,随机分为观察组和对照组,各50例。对照组患者给予茶碱缓释片及N-乙酰半胱氨酸治疗,观察组患者在对照组治疗基础上吸入沙美特罗替卡松粉吸入剂,均治疗6个月,比较治疗前后血清中白细胞介素8(IL-8)、肿瘤坏死因子-α(TNF-α)水平的变化,以评估抗炎疗效,并记录心肺功能的变化,同时观察并比较两组患者治疗前后6 min步行距离(6MWD)及不良反应发生率。结果治疗后,观察组IL-8为(133.5±32.1)ng/L,TNF-α为(140.9±21.3)mg/L,显著低于对照组的(156.8±28.4)ng/L和(181.2±25.4)mg/L( P0.05)。结论沙美特罗替卡松对重度COPD患者肺功能及6MWD有一定影响,对患者的右心功能有明显改善作用,且安全性较好,值得临床应用。%Objective To investigate the effect of salmeterol and fluticasone propionate on cardiopulmonary function and 6 min walking distance in patients with severe COPD. Methods 100 cases of patients with severe COPD who were treated in the hospital from March 2013 to May 2015 were selected as the study objects and were randomly divided into the observation group and the control group, 50 cases in each group. The control group was treated with theophylline sustained-release tablets and N-acetylcysteine. Based on this, the observation group inhaled salmeterol and fluticasone propionate powder inhalant. All patients were treated for 6 months. Serum inter-leukin 8(IL-8)and tumor necrosis factor-α(TNF-α)were compared before and after treatment between the two groups to evalu-ate the anti-inflammatory effect. The changes of cardiopulmonary function were recorded. Meanwhile,the 6 min walking distance (6MWD) and the incidence of adverse reactions were

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

    Science.gov (United States)

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

    2014-01-01

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

  4. Walking - Sensing - Participation

    DEFF Research Database (Denmark)

    Bødker, Mads; Meinhardt, Nina Dam; Browning, David

    Building on ethnographic research and social theory in the field of ‘mobilities’, this workshop paper suggests that field work based on simply walking with people entails a form of embodied participation that informs technological interventions by creating a space within which to address a wider ...... set of experiential or ‘felt’ qualities of living with mobile technologies. Moving from reflections on the value of walking with people, the paper outlines some affordances of a smartphone application built to capture place experiences through walking....

  5. Six-minute walk test in children and adolescents with cystic fibrosis.

    Science.gov (United States)

    Cunha, Maristela Trevisan; Rozov, Tatiana; de Oliveira, Rosangela Caitano; Jardim, José R

    2006-07-01

    The 6-min walk test is a simple, rapid, and low-cost method that determines tolerance to exercise. We examined the reproducibility of the 6-min walk test in 16 children with cystic fibrosis (11 female, 5 male; age range, 11.0 +/- 1.9 years). We related the distance walked and the work performed (distance walked x body weight) with nutritional (body mass index and respiratory muscle strength) and clinical (degree of bronchial obstruction and Shwachman score) status. Patients were asked to walk as far as possible upon verbal command on two occasions. There was no statistical difference between distances walked (582.3 +/- 60 and 598.2 +/- 56.8 m, P = 0.31), heart rate, respiratory rate, pulse oxygen saturation, arterial blood pressure, dyspnea, and percentage of maximal heart rate for age in the two tests. Distance walked correlated (Pearson) with maximal expiratory pressure (98.6 +/- 28.1 cmH2O, r = 0.60, P pressure x heart rate; r = 0.59, P pressure (r = 0.64, P pressure (r = 0.56, P pressure (r = 0.55, P perform in children and adolescents with cystic fibrosis. The distance walked was related to the clinical variables studied. Work in the 6-min walk test may be an additional parameter in the determination of physical capacity.

  6. When Human Walking is a Random Walk

    Science.gov (United States)

    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 α, a measure of the degree to which one stride interval is correlated with previous and subsequent intervals over different time scales. α 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). α 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

  7. The effect of treadmill exercise on gait efficiency during overground walking in adults with cerebral palsy.

    Science.gov (United States)

    Kim, On-Yoo; Shin, Yoon-Kyum; Yoon, Young Kwon; Ko, Eu Jeong; Cho, Sung-Rae

    2015-02-01

    To investigate the effect of treadmill walking exercise as a treatment method to improve gait efficiency in adults with cerebral palsy (CP) and to determine gait efficiency during overground walking after the treadmill walking exercise. Fourteen adults with CP were recruited in the experimental group of treadmill walking exercise. A control group of 7 adults with CP who attended conventional physical therapy were also recruited. The treadmill walking exercise protocol consisted of 3-5 training sessions per week for 1-2 months (total 20 sessions). Gait distance, velocity, VO2, VCO2, O2 rate (mL/kg·min), and O2 cost (mL/kg·m) were assessed at the beginning and at the end of the treadmill walking exercise. The parameters were measured by KB1-C oximeter. After the treadmill walking exercise, gait distance during overground walking up to 6 minutes significantly increased from 151.29±91.79 to 193.93±79.01 m, and gait velocity increased from 28.09±14.29 to 33.49±12.69 m/min (pexercise. On the other hand, gait velocity and O2 cost during overground walking were not significantly changed in the control group. Treadmill walking exercise improved the gait efficiency by decreased energy expenditure during overground walking in adults with CP. Therefore, treadmill walking exercise can be an important method for gait training in adults with CP who have higher energy expenditure.

  8. Toe Walking in Children

    Science.gov (United States)

    ... may simply monitor your child's gait during regular office visits. If a physical problem is contributing to toe walking, treatment options may include: Physical therapy. Gentle stretching of the leg and foot muscles may improve ...

  9. The Act of Walking

    DEFF Research Database (Denmark)

    Vestergaard, Maria Quvang Harck; Olesen, Mette; Helmer, Pernille Falborg

    2014-01-01

    individuals in Denmark conduct and experience walking, and the ‘rationalities’ (Giddens 1984) that lie behind their choice of mobility. It provides insight into how different lifestyles perceive and act walking in their everyday life. Kaufmann (2002) describes how the individual mobility is influenced......’ of mobility (Jensen 2013:111) such as the urban environment, and the infrastructures. Walking has indeed also a ‘software dimension’ as an embodied performance that trigger the human senses (Jensen 2013) and which is closely related to the habitus and identity of the individual (Halprin 1963). The individual...... by individual strategies, values, perceptions and habits, and how appropriation of mobility is constructed through the internalization of standards and values. The act of walking could thus be understood as the result of dynamic internal negotiation of individual, everyday mobility strategies (Lassen 2005...

  10. Chinese translation and validation of the Walking Impairment Questionnaire in patients with peripheral artery disease.

    Science.gov (United States)

    Yan, Bryan P; Lau, James Y; Yu, Check-Man; Au, Kim; Chan, Ka-Wai; Yu, Doris S; Ma, Ronald C; Lam, Yat-Yin; Hiatt, William R

    2011-06-01

    The Walking Impairment Questionnaire (WIQ) is a frequently used questionnaire to evaluate patients with intermittent claudication on four subscales: pain severity, walking distance, walking speed and the ability to climb stairs. The aim of this study is to translate and validate the WIQ in Chinese. After translation and cultural adaptation of the WIQ, 134 patients with intermittent claudication completed the Chinese WIQ and European Quality of Life 5 Dimension (EQ-5D). Walking distances were determined by the 6-minute walk test (6MWT). Correlations between the WIQ, quality of life questionnaire and walking distances were calculated to determine validity. Reliability and internal consistency were determined using the intra-class correlation coefficient (ICC) and Cronbach's alpha (α), respectively. Significant correlations were found between the WIQ score, initial claudication distance (ICD), absolute claudication distance (ACD) and all domains of the EQ-5D (all p ≤ 0.01). Test-retest reliability (ICC = 0.74) and the overall internal consistency determined (α = 0.90) showed good agreement. A lower WIQ score corresponded to shorter walking distances. In conclusion, this study showed that the Chinese version of the WIQ is a valid, reliable and clinically relevant instrument for assessing walking impairment in patients with intermittent claudication.

  11. Walking droplets in confined geometries

    Science.gov (United States)

    Filoux, Boris; Mathieu, Olivier; Vandewalle, Nicolas

    2014-11-01

    When gently placing a droplet onto a vertically vibrated bath, coalescence may be avoided: the drop bounces permanently. Upon increasing forcing acceleration, a drop interacts with the wave it generates, and becomes a ``walker'' with a well defined velocity. In this work, we investigate the confinement of a walker in a mono-dimensional geometry. The system consists of linear submarine channels used as waveguides for a walker. By studying the dynamics of walkers in those channels, we discover some 1D-2D transition. We also propose a model based on an analogy with ``Quantum Wires.'' Finally, we consider the situation of a walker in a circular submarine channel, and examine the behavior of several walking droplets in this system. We show the quantization of the drop distances, and correlate it to their bouncing modes.

  12. Biomechanical analysis of rollator walking

    Directory of Open Access Journals (Sweden)

    Nielsen Linda H

    2006-01-01

    Full Text Available Abstract 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.

  13. Effectiveness of an innovative hip energy storage walking orthosis for improving paraplegic walking: A pilot randomized controlled study.

    Science.gov (United States)

    Yang, Mingliang; Li, Jianjun; Guan, Xinyu; Gao, Lianjun; Gao, Feng; Du, Liangjie; Zhao, Hongmei; Yang, Degang; Yu, Yan; Wang, Qimin; Wang, Rencheng; Ji, Linhong

    2017-09-01

    The high energy cost of paraplegic walking using a reciprocating gait orthosis (RGO) is attributed to limited hip motion and excessive upper limb loading for support. To address the limitation, we designed the hip energy storage walking orthosis (HESWO) which uses a spring assembly on the pelvic shell to store energy from the movements of the healthy upper limbs and flexion-extension of the lumbar spine and hip and returns this energy to lift the pelvis and lower limb to assist with the swing and stance components of a stride. Our aim was to evaluate gait and energy cost indices for the HESWO compared to the RGO in patients with paraplegia. The cross-over design was used in the pilot study. Twelve patients with a complete T4-L5 chronic spinal cord injury underwent gait training using the HESWO and RGO. Gait performance (continuous walking distance, as well as the maximum and comfortable walking speeds) and energy expenditure (at a walking speed of 3.3m/min on a treadmill) were measured at the end of the 4-week training session. Compared to the RGO, the HESWO increased continuous walking distance by 24.7% (Penergy expenditure by 13.9% (P<0.05). Our preliminary results provide support for the use of the HESWO as an alternative support for paraplegic walking. Copyright © 2017. Published by Elsevier B.V.

  14. Walking and proximity to the urban growth boundary and central business district.

    Science.gov (United States)

    Brown, Scott C; Lombard, Joanna; Toro, Matthew; Huang, Shi; Perrino, Tatiana; Perez-Gomez, Gianna; Plater-Zyberk, Elizabeth; Pantin, Hilda; Affuso, Olivia; Kumar, Naresh; Wang, Kefeng; Szapocznik, José

    2014-10-01

    Planners have relied on the urban development boundary (UDB)/urban growth boundary (UGB) and central business district (CBD) to encourage contiguous urban development and conserve infrastructure. However, no studies have specifically examined the relationship between proximity to the UDB/UGB and CBD and walking behavior. To examine the relationship between UDB and CBD distance and walking in a sample of recent Cuban immigrants, who report little choice in where they live after arrival to the U.S. Data were collected in 2008-2010 from 391 healthy, recent Cuban immigrants recruited and assessed within 90 days of arrival to the U.S. who resided throughout Miami-Dade County FL. Analyses in 2012-2013 examined the relationship between UDB and CBD distances for each participant's residential address and purposive walking, controlling for key sociodemographics. Follow-up analyses examined whether Walk Score(®), a built-environment walkability metric based on distance to amenities such as stores and parks, mediated the relationship between purposive walking and each of UDB and CBD distance. Each one-mile increase in distance from the UDB corresponded to an 11% increase in the number of minutes of purposive walking, whereas each one-mile increase from the CBD corresponded to a 5% decrease in the amount of purposive walking. Moreover, Walk Score mediated the relationship between walking and each of UDB and CBD distance. Given the lack of walking and walkable destinations observed in proximity to the UDB/UGB boundary, a sprawl repair approach could be implemented, which strategically introduces mixed-use zoning to encourage walking throughout the boundary's zone. Copyright © 2014 American Journal of Preventive Medicine. Published by Elsevier Inc. All rights reserved.

  15. Unitary equivalence of quantum walks

    Energy Technology Data Exchange (ETDEWEB)

    Goyal, Sandeep K., E-mail: sandeep.goyal@ucalgary.ca [School of Chemistry and Physics, University of KwaZulu-Natal, Private Bag X54001, 4000 Durban (South Africa); Konrad, Thomas [School of Chemistry and Physics, University of KwaZulu-Natal, Private Bag X54001, 4000 Durban (South Africa); National Institute for Theoretical Physics (NITheP), KwaZulu-Natal (South Africa); Diósi, Lajos [Wigner Research Centre for Physics, Institute for Particle and Nuclear Physics, H-1525 Budapest 114, P.O.B. 49 (Hungary)

    2015-01-23

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

  16. RESPONSE TO 6 MINUTE WALK TEST IN HEALTHY ADULTS

    Directory of Open Access Journals (Sweden)

    Vibhuti kiran shah

    2015-12-01

    Full Text Available Background: 6Minute walk test (MWT has been used as a performance based measure of functional exercise capacity in all populations including healthy adults. 6MWT is recommended out of other all timed walked tests due to its reproducibility and ease of administration compared to other longer or shorter time duration tests. It detects changes following interventions to improve exercise tolerance in healthy individuals, to assess the fitness level, used as intervention to improve walking endurance and as predictor of objectively measured aerobic fitness in healthy adults. It is essential to know a level of fitness healthy adults possess in our community, thus aim of this study was to evaluate response to 6MWT in young healthy adults. Method: 50 healthy individuals (25 males and 25 females of 18 - 30 years of age were recruited. The 6MWT was performed as per standard guidelines. All subjects were assessed for the outcome measures by principal investigator at baseline i.e. before and post- 6MWT for following parameters. BP, PR, RR, SPO2, RPE. Results: The mean 6 minute walked distance (6MWD was 635.6+59.07, for men it was 675.0+46.88 and for women it was 596.5+41.41. Out of study population 18% of people covered 70%-80%, 54% people covered 80%-90% and 28% people covered 90%-100% of their predicted distance. Oxygen saturation remained unaltered throughout the walk. Mean resting and walking spo2 values were 96.80+13.55% and 96.71+13.55% (p-value: 0.2288. Pulse rate (PR and respiratory rate (RR were affected by the walk. Mean resting and walking PR was 79.82+9.18 and 142.6+19.62 (p-value: 0.0001 and RR was 18.48+2.78 and 30.20+4.35 (p-value: 0.0001 respectively. Mean resting and walking systolic and diastolic blood pressure was significantly higher in males as compared to females. Conclusion: The 6 minute walk test is a useful measure of functional capacity in healthy adults. There was a difference between predicted distance covered and actual distance

  17. Distância percorrida no teste de caminhada de seis minutos não se relaciona com qualidade de vida em pacientes com bronquiectasias não fibrocísticas Six-minute walk distance is not related to quality of life in patients with non-cystic fibrosis bronchiectasis

    Directory of Open Access Journals (Sweden)

    Patrícia Santos Jacques

    2012-06-01

    Full Text Available OBJETIVO: Avaliar o desempenho físico de pacientes com bronquiectasias não fibrocísticas no teste de caminhada de seis minutos (TC6 e investigar sua associação com a qualidade de vida (QV. Secundariamente, analisar a associação entre a distância percorrida no TC6 (DTC6 com achados clínicos e espirométricos para se identificar preditores para esse desempenho. MÉTODOS: Estudo transversal envolvendo pacientes com bronquiectasias não fibrocísticas, com idade > 18 anos, pelo menos um sintoma respiratório por > 2 anos e VEF1 OBJECTIVE: To evaluate physical performance on the six-minute walk test (6MWT in patients with non-cystic fibrosis bronchiectasis and to investigate its relationship with quality of life (QoL. To identify predictors of exercise performance, we also investigated whether six-minute walk distance (6MWD is associated with clinical and spirometric findings. METHODS: This was a cross-sectional study involving patients with non-cystic fibrosis bronchiectasis (age, > 18 years, with at least one respiratory symptom for > 2 years and an FEV1 < 70% of predicted. Patients underwent clinical evaluation, pulmonary function tests, the 6MWT, and QoL assessment with the Medical Outcomes Study 36-item Short-Form Health Survey (SF-36. RESULTS: We included 70 patients (48 females. Mean age was 54.5 ± 17.7 years, and mean FEV1 was 44.9 ± 14.5% of predicted. The patients were divided into two groups: 6MWD-low (6MWD below the predicted lower limit; n = 23; and 6MWD-norm (normal 6MWD; n = 47. The following variables were significantly lower in the 6MWD-low group than in the 6MWD-norm group: age; age at diagnosis of bronchiectasis; proportion of former smokers; body mass index (BMI; FEV1% of predicted; and MEP% of predicted. There were no significant differences in the SF-36 scores between the groups. In the logistic regression model, lower age and lower BMI were significantly associated with lower 6MWD. CONCLUSIONS: In this sample, there

  18. Walking With Meaning

    Directory of Open Access Journals (Sweden)

    Jennifer McDuff

    2015-09-01

    Full Text Available Physical activity is beneficial for people with dementia, but little research explores subjective experiences of physical activity in this population. Interpretive description guided the analysis of 26 interviews conducted with 12 people with dementia. Three themes described the subjective meaning of everyday physical activity: Participants were attracted to activity because it improved physical well-being, provided social connections, gave opportunity to be in nature, and provided structure and focus; participants experienced impediments to activity because of physical discomfort, environmental factors, lack of enthusiasm, and memory loss; and participants made adjustments by choosing walking over other activities and by being active with others. Results show that physical activity remains important for people with dementia, although they encounter barriers. They may prefer walking with others as a form of activity. Findings could influence how nurses conceptualize wandering and suggest that walking programs could be well received by people with dementia.

  19. Biomechanical conditions of walking

    CERN Document Server

    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.

  20. Bouncing and walking droplets

    Science.gov (United States)

    Molacek, Jan; Bush, John

    2012-11-01

    Motivated by the hydrodynamic quantum analogue system of Yves Couder, we examine the dynamics of silicone oil drops bouncing on a vertically vibrating liquid bath. We report regime diagrams indicating the dependence of the vertical drop motion on the system parameters. A logarithmic spring model for the interface is developed, and provides new rationale for the regime diagrams. We further examine the spatio-temporal evolution of the standing waves created on the bath surface by repeated drop impacts. Measurement of the tangential coefficient of restitution of drops bouncing on a quiescent bath enables us to accurately determine all the major forces acting on the drop during flight and impact. By combining the horizontal and vertical dynamics, we thus develop a model for the walking drops that enables us to rationalize both the extent of the walking regime and the walking speeds. The model predictions compare favorably with experimental data in the parameter range explored.

  1. Ways of Walking

    DEFF Research Database (Denmark)

    Eslambolchilar, Parisa; Bødker, Mads; Chamberlain, Alan

    2016-01-01

    It seems logical to argue that mobile computing technologies are intended for use "on-the-go." However, on closer inspection, the use of mobile technologies pose a number of challenges for users who are mobile, particularly moving around on foot. In engaging with such mobile technologies...... and their envisaged development, we argue that interaction designers must increasingly consider a multitude of perspectives that relate to walking in order to frame design problems appropriately. In this paper, we consider a number of perspectives on walking, and we discuss how these may inspire the design of mobile...... technologies. Drawing on insights from non-representational theory, we develop a partial vocabulary with which to engage with qualities of pedestrian mobility, and we outline how taking more mindful approaches to walking may enrich and inform the design space of handheld technologies....

  2. Path integral distance for data interpretation

    CERN Document Server

    Volchenkov, D

    2015-01-01

    The process of data interpretation is always based on the implicit introduction of equivalence relations on the set of walks over the database. Every equivalence relation on the set of walks specifies a Markov chain describing the transitions of a discrete time random walk. In order to geometrize and interpret the data, we propose the new distance between data units defined as a "Feynman path integral", in which all possible paths between any two nodes in a graph model of the data are taken into account, although some paths are more preferable than others. Such a path integral distance approach to the analysis of databases has proven its efficiency and success, especially on multivariate strongly correlated data where other methods fail to detect structural components (urban planning, historical language phylogenies, music, street fashion traits analysis, etc. ). We believe that it would become an invaluable tool for the intelligent complexity reduction and big data interpretation.

  3. From Walking to Running

    Science.gov (United States)

    Rummel, Juergen; Blum, Yvonne; Seyfarth, Andre

    The implementation of bipedal gaits in legged robots is still a challenge in state-of-the-art engineering. Human gaits could be realized by imitating human leg dynamics where a spring-like leg behavior is found as represented in the bipedal spring-mass model. In this study we explore the gap between walking and running by investigating periodic gait patterns. We found an almost continuous morphing of gait patterns between walking and running. The technical feasibility of this transition is, however, restricted by the duration of swing phase. In practice, this requires an abrupt gait transition between both gaits, while a change of speed is not necessary.

  4. The Act of Walking

    DEFF Research Database (Denmark)

    Vestergaard, Maria Quvang Harck; Olesen, Mette; Helmer, Pernille Falborg

    2014-01-01

    ’ of mobility (Jensen 2013:111) such as the urban environment, and the infrastructures. Walking has indeed also a ‘software dimension’ as an embodied performance that trigger the human senses (Jensen 2013) and which is closely related to the habitus and identity of the individual (Halprin 1963). The individual...... the individuals evaluate, interpret and act (Bourdieu 1984), and how this affects their choice to walk. Therefore it could be questioned if whether an assessment of the physical environment is sufficient to identify all the factors that influence the individual perception of ‘walkability’, or if other influencing...

  5. Walking for data

    DEFF Research Database (Denmark)

    Bødker, Mads; Browning, David; Meinhardt, Nina Dam

    We suggest that ‘walking’ in ethnographic work sensitizes researchers to a particular means of making sense of place. Following a brief conceptual exposition, we present our research tool iMaCam) that supports capturing and representing activities such as walking.......We suggest that ‘walking’ in ethnographic work sensitizes researchers to a particular means of making sense of place. Following a brief conceptual exposition, we present our research tool iMaCam) that supports capturing and representing activities such as walking....

  6. Aperiodic Quantum Random Walks

    CERN Document Server

    Ribeiro, P; Mosseri, R; Ribeiro, Pedro; Milman, Perola; Mosseri, Remy

    2004-01-01

    We generalize the quantum random walk protocol for a particle in a one-dimensional chain, by using several types of biased quantum coins, arranged in aperiodic sequences, in a manner that leads to a rich variety of possible wave function evolutions. Quasiperiodic sequences, following the Fibonacci prescription, are of particular interest, leading to a sub-ballistic wavefunction spreading. In contrast, random sequences leads to diffusive spreading, similar to the classical random walk behaviour. We also describe how to experimentally implement these aperiodic sequences.

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

    Science.gov (United States)

    Damiano, Diane L; Norman, Tracy; Stanley, Christopher J; Park, Hyung-Soon

    2011-06-01

    The extent to which therapeutic, exercise or robotic devices can maximize gait function is a major unresolved issue in neurorehabilitation. Several factors may influence gait outcomes such as similarity of the task to overground walking, degree of coordination within and across limbs, and cycle-to-cycle variability in each device. Our objective was to compare lower extremity kinematics, coordination and variability during four locomotor tasks: overground walking, treadmill walking, elliptical training and stationary cycling in 10 non-disabled adults (6 male; mean age 22.7±2.9 yrs, range 20-29). All first performed four overground walking trials at self-selected speed with mean temporal-spatial data used to pace the other conditions. Joint positions, excursions, and the Gait Deviation Index (GDI) were compared across conditions to evaluate kinematic similarity. Time-series data were correlated within and across limbs to evaluate intralimb and interlimb coordination, respectively. Variability in cadence was quantified to assess how constrained the locomotor rhythm was compared to overground walking. Treadmill walking most closely resembled overground with GDI values nearly overlapping, reinforcing its appropriateness for gait training. Cycling showed the largest GDI difference from overground, with elliptical closer but still a significant distance from all three. Cycling showed greater hip reciprocation Cycling and elliptical showed stronger intralimb synergism at the hip and knee than the other two. Based on kinematics, results suggest that elliptical training may have greater transfer to overground walking than cycling and cycling may be more useful for enhancing reciprocal coordination. Further evaluation of these devices in neurological gait disorders is needed.

  8. Walking for data

    DEFF Research Database (Denmark)

    Bødker, Mads; Browning, David; Meinhardt, Nina Dam

    We suggest that ‘walking’ in ethnographic work sensitizes researchers to a particular means of making sense of place. Following a brief conceptual exposition, we present our research tool iMaCam) that supports capturing and representing activities such as walking....

  9. Walking. Sensing. Participation

    DEFF Research Database (Denmark)

    Bødker, Mads

    2014-01-01

    This paper uses three meditations to contemplate walking, sensing and participation as three ways with which we can extend the notion of ‘experiential computing’ proposed by Yoo (2010). By using the form of meditations, loosely associated concepts that are part introspective and part ‘causative’, i...

  10. Dynamic walking with Dribbel

    NARCIS (Netherlands)

    Dertien, Edwin Christian; Stramigioli, Stefano; Stramigioli, S.

    This paper describes the design and construction of Dribbel, a passivity-based walking robot. Dribbel has been designed and built at the Control Engineering group of the University of Twente. This paper focuses on the practical side: the design approach, construction, electronics, and software

  11. Dynamic walking with Dribbel

    NARCIS (Netherlands)

    Dertien, Edwin

    2006-01-01

    This paper describes the design and construction of Dribbel, a passivity-based walking robot. Dribbel has been designed and built at the Control Engineering group of the University of Twente. This paper focuses on the practical side: the design approach, construction, electronics, and software desig

  12. Walking Advisement: Program Description.

    Science.gov (United States)

    Byram Hills School District, Armonk, NY.

    The Walking Advisement program at Crittenden Middle School in Armonk, New York was started during the 1984-1985 school year. It was based on the work of Alfred Arth, a middle school specialist at the University of Wyoming. Essentially, the program attempts to expand the guidance function of the school by bringing faculty and students together to…

  13. Walking along water

    DEFF Research Database (Denmark)

    Rasmussen, Mattias Borg

    2014-01-01

    Steep slopes, white peaks and deep valleys make up the Andes. As phenomenologists of landscape have told us, different people have different landscapes. By moving across the terrain, walking along, we might get a sense of how this has been carved out by the movement of wind and water, tectonics...

  14. The walking robot project

    Science.gov (United States)

    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.

  15. Deterministic Walks with Choice

    Energy Technology Data Exchange (ETDEWEB)

    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.

  16. Walking along water

    DEFF Research Database (Denmark)

    Rasmussen, Mattias Borg

    2014-01-01

    Steep slopes, white peaks and deep valleys make up the Andes. As phenomenologists of landscape have told us, different people have different landscapes. By moving across the terrain, walking along, we might get a sense of how this has been carved out by the movement of wind and water, tectonics...

  17. Correlation study of Interleukin - 6 levels and 6 - min walk distance in stable chronic obstructive pulmonary disease patients%慢性阻塞性肺疾病患者血清IL-6与6分钟步行距离的相关性研究

    Institute of Scientific and Technical Information of China (English)

    陈建; 葛凯杰

    2011-01-01

    Objective To investigate the relationship between Intedeukin -6 (IL- 6) levels and 6- min walk distance in stable chronic obstructive pulmonary disease (COPD) patients. Methods Between December 2009 and December 2010, 50 stable COPD patients to recruit, we evaluated exercise capacity, using 6 -min walk distance (6MWD); IL- 6 levels were measured in these patients and in 10 controls. Studying the relationship between IL - 6 levels and 6MWD. After logarithmic transformation of IL -6, the data were analyzed using a statistical software package (SPSS 16.0). Results IL -6 levels were higher in COPD patients[4. 34(3.31 ~5.5) ) pg/ml ]than controls [2. 36( 1.42 ~ 3.56) pg/ml ]. The sputum log IL - 6 levels was negatively correlated with 6MWD (r = - 0. 578, P <0. 01 ). Conclusions IL -6 levels were higher in stable COPD patients and can represent systemic inflammation to some degree. IL- 6 levels were correlated with exercise ability. This should be considered when IL- 6 levels are measured in stable chronic obstructive pulmonary disease patients.%目的 探讨稳定期慢性阻塞性肺疾病(COPD)患者血清白介素-6(IL-6)与6分钟步行距离的关系.方法 2009年12月至2010年12月收集稳定期COPD患者50例,测定6分钟步行距离(6MWD);同时选择10例健康志愿者作对照,用ELISA法检测COPD患者和健康志愿者血清IL-6.分析COPD患者血清IL-6与六分钟步行距离的相关性.血清IL-6经对数转换后应用SPSS16.0统汁软件进行统计学分析.结果 稳定期COPI)患者血清IL-6水平[4.34(3.31~5.5)pg/ml]高十健康对照组[2.36(1.42~3.56)pg/ml],两组比较差异有统计学意义(t=-5.2,P=0.000).log IL-6与6MWD旱负相关(r值=-0.578,P<0.01).结论 血清IL-6在稳定期COPD患者中增高,可在一定程度上反应COPD的全身炎症程度,并且与COPD患者的运动能力相关,可作为预测稳定期COPD患者病情及生活质量的有效指标.

  18. Redirecting walking and driving for natural navigation in immersive virtual environments.

    Science.gov (United States)

    Bruder, Gerd; Interrante, Victoria; Phillips, Lane; Steinicke, Frank

    2012-04-01

    Walking is the most natural form of locomotion for humans, and real walking interfaces have demonstrated their benefits for several navigation tasks. With recently proposed redirection techniques it becomes possible to overcome space limitations as imposed by tracking sensors or laboratory setups, and, theoretically, it is now possible to walk through arbitrarily large virtual environments. However, walking as sole locomotion technique has drawbacks, in particular, for long distances, such that even in the real world we tend to support walking with passive or active transportation for longer-distance travel. In this article we show that concepts from the field of redirected walking can be applied to movements with transportation devices. We conducted psychophysical experiments to determine perceptual detection thresholds for redirected driving, and set these in relation to results from redirected walking. We show that redirected walking-and-driving approaches can easily be realized in immersive virtual reality laboratories, e. g., with electric wheelchairs, and show that such systems can combine advantages of real walking in confined spaces with benefits of using vehicle-based self-motion for longer-distance travel.

  19. Contribution of ankle dorsiflexor strength to walking endurance in people with spastic hemiplegia after stroke.

    Science.gov (United States)

    Ng, Shamay S; Hui-Chan, Christina W

    2012-06-01

    (1) To determine the relationships of ankle dorsiflexor strength, ankle plantarflexor strength, and spasticity of the ankle plantarflexors with walking endurance; (2) to determine whether affected ankle dorsiflexor strength makes an independent contribution to walking endurance; and (3) to quantify its relative contribution to the walking endurance of people with spastic hemiplegia after stroke. A cross-sectional study. University-based rehabilitation center. Subjects (N=62) with spastic hemiplegia. Not applicable. Walking endurance was measured by the distance covered in the six-minute walk test (6MWT). Ankle dorsiflexor and plantarflexor strength were measured using a load-cell mounted on a custom-built foot support. Plantarflexor spasticity was measured using the Composite Spasticity Scale. The six-minute walk distances showed stronger positive correlation with affected dorsiflexor strength (r=.793, P≤.000) when compared with affected plantarflexor strength (r=.349, P=.005). Results of the regression model showed that after adjusting for basic demographic and stroke-related impairments, affected ankle dorsiflexor strength remained independently associated with six-minute walk distance, accounting for 48.8% of the variance. This is the first study, to our knowledge, to document the importance of ankle dorsiflexor strength as an independent determinant of walking endurance in stroke survivors with spastic plantarflexors. Our findings suggest that stroke rehabilitation programs aiming to improve walking endurance should include strengthening exercises for the ankle dorsiflexors. Copyright © 2012 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

  20. Walking and Sensing Mobile Lives

    DEFF Research Database (Denmark)

    Bødker, Mads; Meinhardt, Nina Dam

    In this position paper, we discuss how mindful walking with people allow us to explore sensory aspects of mobile lives that are typically absent from research. We present an app that aids researchers collect impressions from a walk.......In this position paper, we discuss how mindful walking with people allow us to explore sensory aspects of mobile lives that are typically absent from research. We present an app that aids researchers collect impressions from a walk....

  1. Snakes and perturbed random walks

    CERN Document Server

    Basak, Gopal

    2011-01-01

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

  2. Walking and Sensing Mobile Lives

    DEFF Research Database (Denmark)

    Bødker, Mads; Meinhardt, Nina Dam

    In this position paper, we discuss how mindful walking with people allow us to explore sensory aspects of mobile lives that are typically absent from research. We present an app that aids researchers collect impressions from a walk.......In this position paper, we discuss how mindful walking with people allow us to explore sensory aspects of mobile lives that are typically absent from research. We present an app that aids researchers collect impressions from a walk....

  3. A random walk down Main Street

    Directory of Open Access Journals (Sweden)

    David Matthew Levinson

    2016-08-01

    Full Text Available US suburbs have often been characterized by their relatively low walk accessibility compared to more urban environments, and US urban environments have been char- acterized by low walk accessibility compared to cities in other countries. Lower overall density in the suburbs implies that activities, if spread out, would have a greater distance between them. But why should activities be spread out instead of developed contiguously? This brief research note builds a positive model for the emergence of contiguous development along “Main Street” to illustrate the trade-offs that result in the built environment we observe. It then suggests some policy interventions to place a “thumb on the scale” to choose which parcels will develop in which sequence to achieve socially preferred outcomes.

  4. Reference value for the 6-minute walk test in children and adolescents : A systematic review

    NARCIS (Netherlands)

    Mylius, C F; Paap, D; Takken, T

    2016-01-01

    INTRODUCTION: The 6-minute walk test is a submaximal exercise test used to quantify the functional exercise capacity in clinical populations. It measures the distance walked within a period of 6-minutes. Obtaining reference values in the pediatric population is especially demanding due to factors as

  5. Foot trajectory approximation using the pendulum model of walking.

    Science.gov (United States)

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

    2014-01-01

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

  6. Quantum walks on Cayley graphs

    Energy Technology Data Exchange (ETDEWEB)

    Lopez Acevedo, O [Laboratoire de Physique Theorique et Modelisation, Universite de Cergy-Pontoise, 2 Avenue Adolphe Chauvin 95302 Cergy Pontoise Cedex (France); Institut fuer Mathematik und Informatik, Ernst-Moritz-Arndt-Universitaet, Friedrich-Ludwig-Jahn Str.15a, 17487 Greifswald (Germany); Gobron, T [Laboratoire de Physique Theorique et Modelisation, Universite de Cergy-Pontoise, 2 Avenue Adolphe Chauvin 95302 Cergy Pontoise Cedex (France)

    2006-01-20

    We address the problem of the construction of quantum walks on Cayley graphs. Our main motivation is the relationship between quantum algorithms and quantum walks. In particular, we discuss the choice of the dimension of the local Hilbert space and consider various classes of graphs on which the structure of quantum walks may differ. We completely characterize quantum walks on free groups and present partial results on more general cases. Some examples are given including a family of quantum walks on the hypercube involving a Clifford algebra.

  7. [Walking abnormalities in children].

    Science.gov (United States)

    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

  8. Fractional random walk lattice dynamics

    CERN Document Server

    Michelitsch, Thomas; Riascos, Alejandro Perez; Nowakowski, Andrzeij; Nicolleau, Franck

    2016-01-01

    We analyze time-discrete and continuous `fractional' random walks on undirected regular networks with special focus on cubic periodic lattices in $n=1,2,3,..$ dimensions.The fractional random walk dynamics is governed by a master equation involving {\\it fractional powers of Laplacian matrices $L^{\\frac{\\alpha}{2}}$}where $\\alpha=2$ recovers the normal walk.First we demonstrate thatthe interval $0\\textless{}\\alpha\\leq 2$ is admissible for the fractional random walk. We derive analytical expressions for fractional transition matrix and closely related the average return probabilities. We further obtain thefundamental matrix $Z^{(\\alpha)}$, and the mean relaxation time (Kemeny constant) for the fractional random walk.The representation for the fundamental matrix $Z^{(\\alpha)}$ relates fractional random walks with normal random walks.We show that the fractional transition matrix elements exihibit for large cubic $n$-dimensional lattices a power law decay of an $n$-dimensional infinite spaceRiesz fractional deriva...

  9. Covering walks in graphs

    CERN Document Server

    Fujie, Futaba

    2014-01-01

    Covering Walks  in Graphs is aimed at researchers and graduate students in the graph theory community and provides a comprehensive treatment on measures of two well studied graphical properties, namely Hamiltonicity and traversability in graphs. This text looks into the famous Kӧnigsberg Bridge Problem, the Chinese Postman Problem, the Icosian Game and the Traveling Salesman Problem as well as well-known mathematicians who were involved in these problems. The concepts of different spanning walks with examples and present classical results on Hamiltonian numbers and upper Hamiltonian numbers of graphs are described; in some cases, the authors provide proofs of these results to illustrate the beauty and complexity of this area of research. Two new concepts of traceable numbers of graphs and traceable numbers of vertices of a graph which were inspired by and closely related to Hamiltonian numbers are introduced. Results are illustrated on these two concepts and the relationship between traceable concepts and...

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

    Directory of Open Access Journals (Sweden)

    Breyer Marie-Kathrin

    2010-08-01

    Full Text Available Abstract Background In patients with COPD progressive dyspnoea leads to a sedentary lifestyle. To date, no studies exist investigating the effects of Nordic Walking in patients with COPD. Therefore, the aim was to determine the feasibility of Nordic Walking in COPD patients at different disease stages. Furthermore we aimed to determine the short- and long-term effects of Nordic Walking on COPD patients' daily physical activity pattern as well as on patients exercise capacity. Methods Sixty COPD patients were randomised to either Nordic Walking or to a control group. Patients of the Nordic Walking group (n = 30; age: 62 ± 9 years; FEV1: 48 ± 19% predicted underwent a three-month outdoor Nordic Walking exercise program consisting of one hour walking at 75% of their initial maximum heart rate three times per week, whereas controls had no exercise intervention. Primary endpoint: daily physical activities (measured by a validated tri-axial accelerometer; secondary endpoint: functional exercise capacity (measured by the six-minute walking distance; 6MWD. Assessment time points in both groups: baseline, after three, six and nine months. Results After three month training period, in the Nordic Walking group time spent walking and standing as well as intensity of walking increased (Δ walking time: +14.9 ± 1.9 min/day; Δ standing time: +129 ± 26 min/day; Δ movement intensity: +0.40 ± 0.14 m/s2 while time spent sitting decreased (Δ sitting time: -128 ± 15 min/day compared to baseline (all: p Conclusions Nordic Walking is a feasible, simple and effective physical training modality in COPD. In addition, Nordic Walking has proven to positively impact the daily physical activity pattern of COPD patients under short- and long-term observation. Clinical trial registration Nordic Walking improves daily physical activities in COPD: a randomised controlled trial - ISRCTN31525632

  11. Individual, employment and psychosocial factors influencing walking to work: Implications for intervention design.

    Science.gov (United States)

    Adams, Emma J; Esliger, Dale W; Taylor, Ian M; Sherar, Lauren B

    2017-01-01

    Promoting walking for the journey to and from work (commuter walking) is a potential strategy for increasing physical activity. Understanding the factors influencing commuter walking is important for identifying target groups and designing effective interventions. This study aimed to examine individual, employment-related and psychosocial factors associated with commuter walking and to discuss the implications for targeting and future design of interventions. 1,544 employees completed a baseline survey as part of the 'Walking Works' intervention project (33.4% male; 36.3% aged logistic regression was used to examine the associations of individual (age, ethnic group, educational qualifications, number of children <16 and car ownership), employment-related (distance lived from work, free car parking at work, working hours, working pattern and occupation) and psychosocial factors (perceived behavioural control, intention, social norms and social support from work colleagues) with commuter walking. Almost half of respondents (n = 587, 49%) were classified as commuter walkers. Those who were aged <30 years, did not have a car, had no free car parking at work, were confident of including some walking or intended to walk to or from work on a regular basis, and had support from colleagues for walking were more likely to be commuter walkers. Those who perceived they lived too far away from work to walk, thought walking was less convenient than using a car for commuting, did not have time to walk, needed a car for work or had always travelled the same way were less likely to be commuter walkers. A number of individual, employment-related and psychosocial factors were associated with commuter walking. Target groups for interventions to promote walking to and from work may include those in older age groups and those who own or have access to a car. Multi-level interventions targeting individual level behaviour change, social support within the workplace and organisational

  12. Minimal Walking Technicolor

    DEFF Research Database (Denmark)

    Frandsen, Mads Toudal

    2007-01-01

    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 under...... 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....

  13. Nordic Walking Classes

    CERN Multimedia

    Fitness Club

    2015-01-01

    Four classes of one hour each are held on Tuesdays. RDV barracks parking at Entrance A, 10 minutes before class time. Spring Course 2015: 05.05/12.05/19.05/26.05 Prices 40 CHF per session + 10 CHF club membership 5 CHF/hour pole rental Check out our schedule and enroll at: https://espace.cern.ch/club-fitness/Lists/Nordic%20Walking/NewForm.aspx? Hope to see you among us! fitness.club@cern.ch

  14. Walking with springs

    Science.gov (United States)

    Sugar, Thomas G.; Hollander, Kevin W.; Hitt, Joseph K.

    2011-04-01

    Developing bionic ankles poses great challenges due to the large moment, power, and energy that are required at the ankle. Researchers have added springs in series with a motor to reduce the peak power and energy requirements of a robotic ankle. We developed a "robotic tendon" that reduces the peak power by altering the required motor speed. By changing the required speed, the spring acts as a "load variable transmission." If a simple motor/gearbox solution is used, one walking step would require 38.8J and a peak motor power of 257 W. Using an optimized robotic tendon, the energy required is 21.2 J and the peak motor power is reduced to 96.6 W. We show that adding a passive spring in parallel with the robotic tendon reduces peak loads but the power and energy increase. Adding a passive spring in series with the robotic tendon reduces the energy requirements. We have built a prosthetic ankle SPARKy, Spring Ankle with Regenerative Kinetics, that allows a user to walk forwards, backwards, ascend and descend stairs, walk up and down slopes as well as jog.

  15. 速度向量成像结合6MWT评价慢性肺动脉高压患者右室功能%Assessment of right ventricular function in patients with chronic pulmonary artery hypertension by using velocity vector imaging associating with 6 minutes walking distance test

    Institute of Scientific and Technical Information of China (English)

    侯海军; 李春伶; 刘卫星; 井茹芳; 马秀珠; 董继红; 树俊莲

    2013-01-01

    Objective To assess the change of RV strain and strain rate in patients with chronic pulmonary arterial hypertension by using velocity vector imaging and to investigate the clinical value of velocity vector imaging. Methods 61 patients with chronic pulmonary hypertension(were divided into mild, moderate and severe groups according pulmonary arterial systolic pressure) and 20 age-matched control were enrolled. Right ventricular structure and function parameters were measured and calculated. Myocardial strain and strain rate of RV were determined by VVI software. In addition, all patients of PH and controls underwent 6-minute walking test. Results Patients with varying degrees of pulmonary hypertension had worse RV performance parameters than those of the controls. Peak systolic myocardial strain and strain rate were significantly impaired in patients with PH compared with controls and were most altered in patients with the most severe PH (P<0.05 for all). Systolic strain and strain rate negatively correlated with 6 minitue walk distance(P<0.01). Conclusion The new Velocity Vector Imaging method provides quantitation of global and regional RV function in patients with PH.%目的 利用速度向量成像技术(VVI)评价慢性肺动脉高压患者右室应变和应变率,结合6 min步行距离试验(6MWT)探讨其在临床中的应用价值.方法选取慢性肺动脉高压患者61例,根据肺动脉收缩压分为轻、中、重3组,20例健康志愿者作为对照.每组病人应用VVI技术分析右室的应变和应变率的变化,同时各组都进行6MWT测试.结果肺动脉高压各组右室大小、右室和左室比例、右室容量均较正常对照组明显增加(P <0.05),射血分数明显减低(P <0.05),6 min步行距离(6MWD)明显减少(P <0.05).右室心肌各节段的应变、应变率均较对照组明显降低(P <0.05).右室整体应变和应变率与6MWD成负相关(P <0.01).结论右室应变和应变率是定量地评价肺动脉高压患者右室功能的可靠方法.

  16. Modulation of Head Movement Control During Walking

    Science.gov (United States)

    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.

  17. Navigation by anomalous random walks on complex networks

    Science.gov (United States)

    Weng, Tongfeng; Zhang, Jie; Khajehnejad, Moein; Small, Michael; Zheng, Rui; Hui, Pan

    2016-11-01

    Anomalous random walks having long-range jumps are a critical branch of dynamical processes on networks, which can model a number of search and transport processes. However, traditional measurements based on mean first passage time are not useful as they fail to characterize the cost associated with each jump. Here we introduce a new concept of mean first traverse distance (MFTD) to characterize anomalous random walks that represents the expected traverse distance taken by walkers searching from source node to target node, and we provide a procedure for calculating the MFTD between two nodes. We use Lévy walks on networks as an example, and demonstrate that the proposed approach can unravel the interplay between diffusion dynamics of Lévy walks and the underlying network structure. Moreover, applying our framework to the famous PageRank search, we show how to inform the optimality of the PageRank search. The framework for analyzing anomalous random walks on complex networks offers a useful new paradigm to understand the dynamics of anomalous diffusion processes, and provides a unified scheme to characterize search and transport processes on networks.

  18. Navigation by anomalous random walks on complex networks

    CERN Document Server

    Weng, Tongfeng; Khajehnejad, Moein; Small, Michael; Zheng, Rui; Hui, Pan

    2016-01-01

    Anomalous random walks having long-range jumps are a critical branch of dynamical processes on networks, which can model a number of search and transport processes. However, traditional measurements based on mean first passage time are not useful as they fail to characterize the cost associated with each jump. Here we introduce a new concept of mean first traverse distance (MFTD) to characterize anomalous random walks that represents the expected traverse distance taken by walkers searching from source node to target node, and we provide a procedure for calculating the MFTD between two nodes. We use Levy walks on networks as an example, and demonstrate that the proposed approach can unravel the interplay between diffusion dynamics of Levy walks and the underlying network structure. Interestingly, applying our framework to the famous PageRank search, we can explain why its damping factor empirically chosen to be around 0.85. The framework for analyzing anomalous random walks on complex networks offers a new us...

  19. Quantum walks on general graphs

    CERN Document Server

    Kendon, V

    2003-01-01

    A scheme for a discrete time quantum walk on a general graph of N vertices with undirected edges is given, and compared with the continuous time quantum walk on a general graph introduced by Farhi and Gutmann [PRA 58 915 (1998)]. Both walks are contrasted with the examples of quantum walks in the literature treating graphs of fixed, small (< log N) degree. This illustrates the way in which extra information about the graph allows more efficient algorithms to be designed. To obtain a quantum speed up over classical for comparable resources it is necessary to code the position space of the quantum walk into a qubit register (or equivalent). The role of the oracle is also discussed and an efficient gate sequence is presented for implementing a discrete quantum walk given one copy of a quantum state encoding the adjacency matrix of the graph.

  20. Quantum walks on Cayley graphs

    CERN Document Server

    Acevedo, O L

    2006-01-01

    We address the problem of the construction of quantum walks on Cayley graphs. Our main motivation is the relationship between quantum algorithms and quantum walks. Thus we consider quantum walks on a general basis and try to classify them as a preliminary step in the construction of new algorithms that could be devised in this way. In particular, we discuss the choice of the dimension of the local Hilbert space, and consider various classes of graphs on which the structure of quantum walks may differ. We characterize completely the quantum walks on free groups and present partial results on more general cases. Examples are given among which a family of quantum walks on the hypercube involving a Clifford Algebra.

  1. An exploration of impaired walking dynamics and fatigue in Multiple Sclerosis

    Directory of Open Access Journals (Sweden)

    Burschka Janina M

    2012-12-01

    Full Text Available Abstract Background Physical disability in multiple sclerosis (MS is frequently characterized by impaired ambulation. Although walking tests have been successfully employed to assess walking ability in MS patients, data analytic procedures have predominantly relied on result-oriented parameters (e.g. total distance covered during a given amount of time, whereas process-oriented, dynamic walking patterns have mostly been ignored. This is striking, since healthy individuals have been observed to display a stereotypical U-shaped pattern of walking speed during timed walking, characterized by relatively high speed during the initial phase, subsequent slowing and final acceleration. Objective of the current study was to test the utility of the 6 min Walk (6MW and the 12 min Walk (12MW for revealing putatively abnormal temporal dynamic features of walking in MS. Methods A group of 37 MS patients was divided into subgroups with regard to their level of disability analyzed with the Expanded Disability Status Scale (EDSS; Mild MS Group, n = 20, EDSS 0 – 3.5; Moderate MS Group, n = 17, EDSS 4 – 5. Subsequently, both groups were compared to age-matched healthy controls (n = 25 on both tests with regard to result-oriented characteristics (mean walking speed, as well as dynamic features (mean decline in walking speed, degree of observed U-shape. Results Both MS groups showed a significantly lower mean walking speed than healthy controls, independent of test duration. Compared to controls, the Moderate MS Group also slowed down more rapidly throughout both tests. The same pronounced decline in walking speed was observed for the Mild MS Group in case of the 12MW. Additionally, for both MS groups an attenuated U-shaped velocity pattern was observed relative to controls in the 6MW. Patients' subjective fatigue scores were more strongly correlated with the decline in walking speed than with the common parameter of mean walking speed in the 6MW

  2. Attuning one's steps to visual targets reduces comfortable walking speed in both young and older adults.

    Science.gov (United States)

    Peper, C Lieke E; de Dreu, Miek J; Roerdink, Melvyn

    2015-03-01

    Comfortable walking speed (CWS) is indicative of clinically relevant factors in the elderly, such as fall risk and mortality. Standard CWS tests involve walking on a straight, unobstructed surface, while in reality surfaces are uneven and cluttered and so walkers rely on visually guided adaptations to avoid trips or slips. Hence, the predictive value of CWS may be expected to increase when assessed for walking in more realistic (visually guided) conditions. We examined CWS in young (n=18) and older (n=18) adults for both overground and treadmill walking. Overground CWS was assessed using the 10-meter walk test with and without visual stepping targets. For treadmill walking, four conditions were examined: (i) uncued walking, and (ii-iv) cued walking with visual stepping targets where the inter-stepping target distance varied by 0%, 20%, or 40%. Pre-experimental measures were taken so that the average inter-stepping target distance could be adjusted for each belt speed based on each participant's self-selected gait characteristics. Results showed that CWS was significantly slower when stepping targets were present in both overground (pCWS, even when the patterning of these targets matched the participant's own gait pattern (viz. 0%-treadmill-walking condition). Results from the treadmill-walking task showed that the amount of variation in inter-stepping target distance did not differentially affect CWS. Our results suggest that it may be worthwhile in clinical assessments to not only determine walking speed using standard conditions but also in situations that require visually guided stepping.

  3. Cookie branching random walks

    CERN Document Server

    Bartsch, Christian; Kochler, Thomas; Müller, Sebastian; Popov, Serguei

    2011-01-01

    We consider a branching random walk on $\\Z$, where the particles behave differently in visited and unvisited sites. Informally, each site on the positive half-line contains initially a cookie. On the first visit of a site its cookie is removed and particles at positions with a cookie reproduce and move differently from particles on sites without cookies. Therefore, the movement and the reproduction of the particles depend on the previous behaviour of the population of particles. We study the question if the process is recurrent or transient, i.e., whether infinitely many particles visit the origin or not.

  4. Collisions of Random Walks

    CERN Document Server

    Barlow, Martin T; Sousi, Perla

    2010-01-01

    A recurrent graph $G$ has the infinite collision property if two independent random walks on $G$, started at the same point, collide infinitely often a.s. We give a simple criterion in terms of Green functions for a graph to have this property, and use it to prove that a critical Galton-Watson tree with finite variance conditioned to survive, the incipient infinite cluster in $\\Z^d$ with $d \\ge 19$ and the uniform spanning tree in $\\Z^2$ all have the infinite collision property. For power-law combs and spherically symmetric trees, we determine precisely the phase boundary for the infinite collision property.

  5. A mathematical nature walk

    CERN Document Server

    Adam, John A

    2009-01-01

    How heavy is that cloud? Why can you see farther in rain than in fog? Why are the droplets on that spider web spaced apart so evenly? If you have ever asked questions like these while outdoors, and wondered how you might figure out the answers, this is a book for you. An entertaining and informative collection of fascinating puzzles from the natural world around us, A Mathematical Nature Walk will delight anyone who loves nature or math or both. John Adam presents ninety-six questions about many common natural phenomena--and a few uncommon ones--and then shows how to answer them using mostly b

  6. Persistence of random walk records

    Science.gov (United States)

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

    2014-06-01

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

  7. Quantum Walks on the Hypercube

    CERN Document Server

    Moore, Cristopher; Moore, Cristopher; Russell, Alexander

    2001-01-01

    Recently, it has been shown that one-dimensional quantum walks can mix more quickly than classical random walks, suggesting that quantum Monte Carlo algorithms can outperform their classical counterparts. We study two quantum walks on the n-dimensional hypercube, one in discrete time and one in continuous time. In both cases we show that the quantum walk mixes in (\\pi/4)n steps, faster than the O(n log n) steps required by the classical walk. In the continuous-time case, the probability distribution is {\\em exactly} uniform at this time. More importantly, these walks expose several subtleties in the definition of mixing time for quantum walks. Even though the continuous-time walk has an O(n) instantaneous mixing time at which it is precisely uniform, it never approaches the uniform distribution when the stopping time is chosen randomly as in [AharonovAKV2001]. Our analysis treats interference between terms of different phase more carefully than is necessary for the walk on the cycle; previous general bounds p...

  8. Physical implementation of quantum walks

    CERN Document Server

    Manouchehri, Kia

    2013-01-01

    Given the extensive application of random walks in virtually every science related discipline, we may be at the threshold of yet another problem solving paradigm with the advent of quantum walks. Over the past decade, quantum walks have been explored for their non-intuitive dynamics, which may hold the key to radically new quantum algorithms. This growing interest has been paralleled by a flurry of research into how one can implement quantum walks in laboratories. This book presents numerous proposals as well as actual experiments for such a physical realization, underpinned by a wide range of

  9. Validity of FitBit, Jawbone UP, Nike+ and other wearable devices for level and stair walking.

    Science.gov (United States)

    Huang, Yangjian; Xu, Junkai; Yu, Bo; Shull, Peter B

    2016-07-01

    Increased physical activity can provide numerous health benefits. The relationship between physical activity and health assumes reliable activity measurements including step count and distance traveled. This study assessed step count and distance accuracy for Nike+ FuelBand, Jawbone UP 24, Fitbit One, Fitbit Flex, Fitbit Zip, Garmin Vivofit, Yamax CW-701, and Omron HJ-321 during level, upstairs, and downstairs walking in healthy adults. Forty subjects walked on flat ground (400m), upstairs (176 steps), and downstairs (176 steps), and a subset of 10 subjects performed treadmill walking trials to assess the influence of walking speed on accuracy. Activity monitor measured step count and distance values were compared with actual step count (determined from video recordings) and distance to determine accuracy. For level walking, step count errors in Yamax CW-701, Fitbit Zip, Fitbit One, Omron HJ-321, and Jawbone UP 24 were within 1% and distance errors in Fitbit Zip and Yamax CW-701 were within 5%. Garmin Vivofit and Omron HJ-321 were the most accurate in estimating step count for stairs with errors less than 4%. An important finding is that all activity monitors overestimated distance for stair walking by at least 45%. In general, there were not accuracy differences among activity monitors for stair walking. Accuracy did not change between moderate and fast walking speeds, though slow walking increased errors for some activity monitors. Nike+ FuelBand was the least accurate step count estimator during all walking tasks. Caution should be taken when interpreting step count and distance estimates for activities involving stairs. Copyright © 2016 Elsevier B.V. All rights reserved.

  10. Acute Cardiorespiratory and Metabolic Responses During Exoskeleton-Assisted Walking Overground Among Persons with Chronic Spinal Cord Injury.

    Science.gov (United States)

    Evans, Nicholas; Hartigan, Clare; Kandilakis, Casey; Pharo, Elizabeth; Clesson, Ismari

    2015-01-01

    Lower extremity robotic exoskeleton technology is being developed with the promise of affording people with spinal cord injury (SCI) the opportunity to stand and walk. The mobility benefits of exoskeleton-assisted walking can be realized immediately, however the cardiorespiratory and metabolic benefits of this technology have not been thoroughly investigated. The purpose of this pilot study was to evaluate the acute cardiorespiratory and metabolic responses associated with exoskeleton-assisted walking overground and to determine the degree to which these responses change at differing walking speeds. Five subjects (4 male, 1 female) with chronic SCI (AIS A) volunteered for the study. Expired gases were collected during maximal graded exercise testing and two, 6-minute bouts of exoskeleton-assisted walking overground. Outcome measures included peak oxygen consumption (V̇O2peak), average oxygen consumption (V̇O2avg), peak heart rate (HRpeak), walking economy, metabolic equivalent of tasks for SCI (METssci), walk speed, and walk distance. Significant differences were observed between walk-1 and walk-2 for walk speed, total walk distance, V̇O2avg, and METssci. Exoskeleton-assisted walking resulted in %V̇O2peak range of 51.5% to 63.2%. The metabolic cost of exoskeleton-assisted walking ranged from 3.5 to 4.3 METssci. Persons with motor-complete SCI may be limited in their capacity to perform physical exercise to the extent needed to improve health and fitness. Based on preliminary data, cardiorespiratory and metabolic demands of exoskeleton-assisted walking are consistent with activities performed at a moderate intensity.

  11. Random-walk enzymes.

    Science.gov (United States)

    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.

  12. Random-walk enzymes

    Science.gov (United States)

    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.

  13. Random-walk enzymes

    Science.gov (United States)

    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

  14. Speed and distance requirements for community ambulation: a systematic review.

    Science.gov (United States)

    Salbach, Nancy M; O'Brien, Kelly; Brooks, Dina; Irvin, Emma; Martino, Rosemary; Takhar, Pam; Chan, Sylvia; Howe, Jo-Anne

    2014-01-01

    To provide an overview of the research literature on distance and speed requirements for adults to walk outside the home. We conducted a systematic review and searched PubMed, MEDLINE (Ovid), EMBASE, CINAHL, Scopus, PEDro, and The Cochrane Library from 1948 to May 2012, and other sources. Search terms included communities, walk, ambulation, and neighborhood. Full-text peer-reviewed articles written in English, French, or Spanish reporting distance and/or speed requirements for individuals walking outside the home were considered eligible. Two authors independently screened titles and abstracts. One author reviewed full-text articles to determine inclusion. Of the 3191 titles and abstracts screened, 15 studies (.47%) were selected for detailed review. One author appraised methodological quality. Inadequate description of the reliability of the measurement methods and the population of the town/city assessed was noted. One author extracted data from included studies. A second reviewer independently verified extracted data for accuracy. Seven studies examining 24 community sites and crosswalks in the United States, Australia, and Singapore were included. Three sites with the largest mean distance requirements for adults to walk were club warehouses (677m), superstores (183-607m), and hardware stores (566m). Three sites with the lowest mean distance requirements were walking at the front (16m) and back (19m) of the house, and at cemeteries (18m). The average speed required to cross the street in the time of a walk signal varied from .44 to 1.32m/s. Distance and speed requirements for adults to walk in the community environment vary widely. Findings are relevant to judging capacity for community ambulation to carry out essential activities of daily living, educating patients, and setting rehabilitation goals. Copyright © 2014 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

  15. Self-reported walking ability in persons with chronic stroke and the relationship with gait performance tests.

    Science.gov (United States)

    Brogårdh, Christina; Flansbjer, Ulla-Britt; Lexell, Jan

    2012-10-01

    To assess self-reported walking ability in individuals with chronic stroke and to determine the relationship with gait performance tests. Descriptive analysis of a convenience sample. A university hospital rehabilitation medicine clinic. Fifty ambulatory community-dwelling poststroke individuals (mean age, 64 years [range, 44-74 years] and mean time since stroke onset 42 months [range, 6-101 months]). The Walking Impact Scale (the Walk-12) to assess self-reported walking ability, and the Timed "Up & Go" test, 10-m Comfortable Gait Speed and Fast Gait Speed tests, and 6-Minute Walk Test to assess gait performance. A majority of the participants (94%) reported limitations in their walking ability. The most common limitations were related to standing or walking, walking speed and distance, effort, and gait quality aspects. The ability to run was reported as most affected, whereas the need for support indoors or outdoors was least affected. Significant correlations (P limitations in their walking ability. The relationship between the Walk-12 and the 4 gait performance tests indicates that self-reports and quantitative assessments are associated. Because the Walk-12 reflects broader dimensions than the gait performance tests, it can be a complementary tool when walking ability in persons with chronic stroke is evaluated. Copyright © 2012 American Academy of Physical Medicine and Rehabilitation. Published by Elsevier Inc. All rights reserved.

  16. Quantum walks and search algorithms

    CERN Document Server

    Portugal, Renato

    2013-01-01

    This book addresses an interesting area of quantum computation called quantum walks, which play an important role in building quantum algorithms, in particular search algorithms. Quantum walks are the quantum analogue of classical random walks. It is known that quantum computers have great power for searching unsorted databases. This power extends to many kinds of searches, particularly to the problem of finding a specific location in a spatial layout, which can be modeled by a graph. The goal is to find a specific node knowing that the particle uses the edges to jump from one node to the next. This book is self-contained with main topics that include: Grover's algorithm, describing its geometrical interpretation and evolution by means of the spectral decomposition of the evolution operater Analytical solutions of quantum walks on important graphs like line, cycles, two-dimensional lattices, and hypercubes using Fourier transforms Quantum walks on generic graphs, describing methods to calculate the limiting d...

  17. Walking around to grasp interaction

    DEFF Research Database (Denmark)

    Lykke, Marianne; Jantzen, Christian

    2013-01-01

    with the sound installations. The aim was to gain an understanding of the role of the in-teraction, if interaction makes a difference for the understanding of the sound art. 30 walking interviews were carried out at ZKM, Karlsruhe with a total of 57 museum guests, individuals or groups. During the walk......The paper presents experiences from a study using walk-alongs to provide insight into museum visitors’ experience with interactive features of sound art installations. The overall goal of the study was to learn about the participants’ opinions and feelings about the possibility of interaction...... knowledge of spa-tial conditions, e.g. noise, crowds, darkness provided a profound and shared un-derstanding of e.g. the visitors’ engagement in and dislike of the installations. Another finding concerns group walking that, compared to walking with a sin-gle person, generated a diversified discussion...

  18. Human treadmill walking needs attention

    Directory of Open Access Journals (Sweden)

    Daniel Olivier

    2006-08-01

    Full Text Available Abstract Background The aim of the study was to assess the attentional requirements of steady state treadmill walking in human subjects using a dual task paradigm. The extent of decrement of a secondary (cognitive RT task provides a measure of the attentional resources required to maintain performance of the primary (locomotor task. Varying the level of difficulty of the reaction time (RT task is used to verify the priority of allocation of attentional resources. Methods 11 healthy adult subjects were required to walk while simultaneously performing a RT task. Participants were instructed to bite a pressure transducer placed in the mouth as quickly as possible in response to an unpredictable electrical stimulation applied on the back of the neck. Each subject was tested under five different experimental conditions: simple RT task alone and while walking, recognition RT task alone and while walking, walking alone. A foot switch system composed of a pressure sensitive sensor was placed under the heel and forefoot of each foot to determine the gait cycle duration. Results Gait cycle duration was unchanged (p > 0.05 by the addition of the RT task. Regardless of the level of difficulty of the RT task, the RTs were longer during treadmill walking than in sitting conditions (p 0.05 was found between the attentional demand of the walking task and the decrement of performance found in the RT task under varying levels of difficulty. This finding suggests that the healthy subjects prioritized the control of walking at the expense of cognitive performance. Conclusion We conclude that treadmill walking in young adults is not a purely automatic task. The methodology and outcome measures used in this study provide an assessment of the attentional resources required by walking on the treadmill at a steady state.

  19. Water-walking devices

    Science.gov (United States)

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

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

  20. Walking for art's sake

    CERN Multimedia

    2005-01-01

      The man who compared himself to a proton ! On 20 May, Gianni Motti went down into the LHC tunnel and walked around the 27 kilometres of the underground ring at an average, unaccelerated pace of 5 kph. This was an artistic rather than an athletic performance, aimed at drawing a parallel between the fantastic speed of the beams produced by the future accelerator and the leisurely stroll of a human. The artist, who hails from Lombardy, was accompanied by cameraman Ivo Zanetti, who filmed the event from start to finish, and physicist Jean-Pierre Merlo. The first part of the film can be seen at the Villa Bernasconi, 8 route du Grand-Lancy, Grand Lancy, until 26 June.

  1. Walking for art's sake

    CERN Document Server

    2005-01-01

    The man who compared himself to a proton ! On 20 May, Gianni Motti went down into the LHC tunnel and walked around the 27 kilometres of the underground ring at an average, unaccelerated pace of 5 kph. This was an artistic rather than an athletic performance, aimed at drawing a parallel between the fantastic speed of the beams produced by the future accelerator and the leisurely stroll of a human. The artist, who hails from Lombardy, was accompanied by cameraman Ivo Zanetti, who filmed the event from start to finish, and physicist Jean-Pierre Merlo. The first part of the film can be seen at the Villa Bernasconi, 8 route du Grand-Lancy, Grand Lancy, until 26 June.

  2. walk around Irkutsk

    Directory of Open Access Journals (Sweden)

    Elena Grigoryeva

    2011-08-01

    Full Text Available It is noteworthy that this country develops through two types of events: either through a jubilee or through a catastrophe.It seems that Irkutsk Airport will be built only after the next crash. At least the interest to this problem returns regularly after sad events, and this occurs almost half a century (a jubilee, too! – the Council of Ministers decided to relocate the Airport away from the city as long ago as 1962. The Airport does not relate to the topic of this issue, but an attentive reader understands that it is our Carthage, and that the Airport should be relocated. The Romans coped with it faster and more effectively.Back to Irkutsk’s jubilee, we should say that we will do without blare of trumpets. We will just make an unpretentious walk around the city in its summer 350. Each our route covers new (some of them have been completed by the jubilee and old buildings, some of them real monuments. All these buildings are integrated into public spaces of different quality and age.We will also touch on the problems, for old houses, especially the wooden ones often provoke a greedy developer to demolish or to burn them down. Thus a primitive thrift estimates an output of additional square meters. Not to mention how attractive it is to seize public spaces without demolition or without reallocation of the dwellers. Or, rather, the one who is to preserve, to cherish and to improve such houses for the good of the citizens never speaks about this sensitive issue. So we have to do it.Walking is a no-hurry genre, unlike the preparation for the celebration. Walking around the city you like is a pleasant and cognitive process. It will acquaint the architects with the works of their predecessors and colleagues. We hope that such a walk may be interesting for Irkutsk citizens and visitors, too. Isn’t it interesting to learn “at first hand” the intimate details of the restoration of the Trubetskoys’ estate

  3. Walking indoors, walking outdoors: an fMRI study

    Directory of Open Access Journals (Sweden)

    Riccardo eDalla Volta

    2015-10-01

    Full Text Available 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.

  4. Visual control of walking velocity.

    Science.gov (United States)

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

    2011-06-01

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

  5. Kinematic Adaptations of Forward and Backward Walking on Land and in Water

    Directory of Open Access Journals (Sweden)

    Cadenas-Sanchez Cristina

    2015-12-01

    Full Text Available The aim of this study was to compare sagittal plane lower limb kinematics during walking on land and submerged to the hip in water. Eight healthy adults (age 22.1 ± 1.1 years, body height 174.8 ± 7.1 cm, body mass 63.4 ± 6.2 kg were asked to cover a distance of 10 m at comfortable speed with controlled step frequency, walking forward or backward. Sagittal plane lower limb kinematics were obtained from three dimensional video analysis to compare spatiotemporal gait parameters and joint angles at selected events using two-way repeated measures ANOVA. Key findings were a reduced walking speed, stride length, step length and a support phase in water, and step length asymmetry was higher compared to the land condition (p<0.05. At initial contact, knees and hips were more flexed during walking forward in water, whilst, ankles were more dorsiflexed during walking backward in water. At final stance, knees and ankles were more flexed during forward walking, whilst the hip was more flexed during backward walking. These results show how walking in water differs from walking on land, and provide valuable insights into the development and prescription of rehabilitation and training programs.

  6. Kinematic Adaptations of Forward And Backward Walking on Land and in Water

    Science.gov (United States)

    Cadenas-Sanchez, Cristina; Arellano, Raúl; Vanrenterghem, Jos; López-Contreras, Gracia

    2015-01-01

    The aim of this study was to compare sagittal plane lower limb kinematics during walking on land and submerged to the hip in water. Eight healthy adults (age 22.1 ± 1.1 years, body height 174.8 ± 7.1 cm, body mass 63.4 ± 6.2 kg) were asked to cover a distance of 10 m at comfortable speed with controlled step frequency, walking forward or backward. Sagittal plane lower limb kinematics were obtained from three dimensional video analysis to compare spatiotemporal gait parameters and joint angles at selected events using two-way repeated measures ANOVA. Key findings were a reduced walking speed, stride length, step length and a support phase in water, and step length asymmetry was higher compared to the land condition (p<0.05). At initial contact, knees and hips were more flexed during walking forward in water, whilst, ankles were more dorsiflexed during walking backward in water. At final stance, knees and ankles were more flexed during forward walking, whilst the hip was more flexed during backward walking. These results show how walking in water differs from walking on land, and provide valuable insights into the development and prescription of rehabilitation and training programs. PMID:26839602

  7. Center of mass mechanics of chimpanzee bipedal walking.

    Science.gov (United States)

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

    2015-03-01

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

  8. The mechanics of walking in children.

    Science.gov (United States)

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

    1983-10-01

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

  9. The Dead Walk

    Directory of Open Access Journals (Sweden)

    Bill Phillips

    2014-02-01

    Full Text Available Monsters have always enjoyed a significant presence in the human imagination, and religion was instrumental in replacing the physical horror they engendered with that of a moral threat. Zombies, however, are amoral – their motivation purely instinctive and arbitrary, yet they are, perhaps, the most loathed of all contemporary monsters. One explanation for this lies in the theory of the uncanny valley, proposed by robotics engineer Masahiro Mori. According to the theory, we reserve our greatest fears for those things which seem most human, yet are not – such as dead bodies. Such a reaction is most likely a survival mechanism to protect us from danger and disease – a mechanism even more essential when the dead rise up and walk. From their beginnings zombies have reflected western societies’ greatest fears – be they of revolutionary Haitians, women, or communists. In recent years the rise in the popularity of the zombie in films, books and television series reflects our fears for the planet, the economy, and of death itself

  10. Big power from walking

    Science.gov (United States)

    Illenberger, Patrin K.; Madawala, Udaya K.; Anderson, Iain A.

    2016-04-01

    Dielectric Elastomer Generators (DEG) offer an opportunity to capture the energy otherwise wasted from human motion. By integrating a DEG into the heel of standard footwear, it is possible to harness this energy to power portable devices. DEGs require substantial auxiliary systems which are commonly large, heavy and inefficient. A unique challenge for these low power generators is the combination of high voltage and low current. A void exists in the semiconductor market for devices that can meet these requirements. Until these become available, existing devices must be used in an innovative way to produce an effective DEG system. Existing systems such as the Bi-Directional Flyback (BDFB) and Self Priming Circuit (SPC) are an excellent example of this. The BDFB allows full charging and discharging of the DEG, improving power gained. The SPC allows fully passive voltage boosting, removing the priming source and simplifying the electronics. This paper outlines the drawbacks and benefits of active and passive electronic solutions for maximizing power from walking.

  11. Integrated photonic quantum walks

    Science.gov (United States)

    Gräfe, Markus; Heilmann, René; Lebugle, Maxime; Guzman-Silva, Diego; Perez-Leija, Armando; Szameit, Alexander

    2016-10-01

    Over the last 20 years quantum walks (QWs) have gained increasing interest in the field of quantum information science and processing. In contrast to classical walkers, quantum objects exhibit intrinsic properties like non-locality and non-classical many-particle correlations, which renders QWs a versatile tool for quantum simulation and computation as well as for a deeper understanding of genuine quantum mechanics. Since they are highly controllable and hardly interact with their environment, photons seem to be ideally suited quantum walkers. In order to study and exploit photonic QWs, lattice structures that allow low loss coherent evolution of quantum states are demanded. Such requirements are perfectly met by integrated optical waveguide devices that additionally allow a substantial miniaturization of experimental settings. Moreover, by utilizing the femtosecond direct laser writing technique three-dimensional waveguide structures are capable of analyzing QWs also on higher dimensional geometries. In this context, advances and findings of photonic QWs are discussed in this review. Various concepts and experimental results are presented covering, such as different quantum transport regimes, the Boson sampling problem, and the discrete fractional quantum Fourier transform.

  12. Walking Robot Locomotion System Conception

    Directory of Open Access Journals (Sweden)

    Ignatova D.

    2014-09-01

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

  13. Quantum Snake Walk on Graphs

    CERN Document Server

    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.

  14. Localization of reinforced random walks

    CERN Document Server

    Tarrès, Pierre

    2011-01-01

    We describe and analyze how reinforced random walks can eventually localize, i.e. only visit finitely many sites. After introducing vertex and edge self-interacting walks on a discrete graph in a general setting, and stating the main results and conjectures so far on the topic, we present martingale techniques that provide an alternative proof of the a.s. localization of vertex-reinforced random walks (VRRWs) on the integers on finitely many sites and, with positive probability, on five consecutive sites, initially proved by Pemantle and Volkov (1999). Next we introduce the continuous time-lines representation (sometimes called Rubin construction) and its martingale counterpart, and explain how it has been used to prove localization of some reinforced walks on one attracting edge. Then we show how a modified version of this construction enables one to propose a new short proof of the a.s. localization of VRRWs on five sites on Z.

  15. Bouchaud walks with variable drift

    CERN Document Server

    Parra, Manuel Cabezas

    2010-01-01

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

  16. Improving the accuracy of walking piezo motors.

    Science.gov (United States)

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

    2014-05-01

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

  17. Walking behavior in technicolored GUTs

    Energy Technology Data Exchange (ETDEWEB)

    Doff, A. [Universidade Tecnologica Federal do Parana-UTFPR-COMAT, Pato Branco, PR (Brazil)

    2009-03-15

    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. (orig.)

  18. Intraspinal microstimulation produces over-ground walking in anesthetized cats

    Science.gov (United States)

    Holinski, B. J.; Mazurek, K. A.; Everaert, D. G.; Toossi, A.; Lucas-Osma, A. M.; Troyk, P.; Etienne-Cummings, R.; Stein, R. B.; Mushahwar, V. K.

    2016-10-01

    Objective. Spinal cord injury causes a drastic loss of motor, sensory and autonomic function. The goal of this project was to investigate the use of intraspinal microstimulation (ISMS) for producing long distances of walking over ground. ISMS is an electrical stimulation method developed for restoring motor function by activating spinal networks below the level of an injury. It produces movements of the legs by stimulating the ventral horn of the lumbar enlargement using fine penetrating electrodes (≤50 μm diameter). Approach. In each of five adult cats (4.2-5.5 kg), ISMS was applied through 16 electrodes implanted with tips targeting lamina IX in the ventral horn bilaterally. A desktop system implemented a physiologically-based control strategy that delivered different stimulation patterns through groups of electrodes to evoke walking movements with appropriate limb kinematics and forces corresponding to swing and stance. Each cat walked over an instrumented 2.9 m walkway and limb kinematics and forces were recorded. Main results. Both propulsive and supportive forces were required for over-ground walking. Cumulative walking distances ranging from 609 to 835 m (longest tested) were achieved in three animals. In these three cats, the mean peak supportive force was 3.5 ± 0.6 N corresponding to full-weight-support of the hind legs, while the angular range of the hip, knee, and ankle joints were 23.1 ± 2.0°, 29.1 ± 0.2°, and 60.3 ± 5.2°, respectively. To further demonstrate the viability of ISMS for future clinical use, a prototype implantable module was successfully implemented in a subset of trials and produced comparable walking performance. Significance. By activating inherent locomotor networks within the lumbosacral spinal cord, ISMS was capable of producing bilaterally coordinated and functional over-ground walking with current amplitudes <100 μA. These exciting results suggest that ISMS may be an effective intervention for restoring functional

  19. Falling while walking: A hidden contributor to pedestrian injury.

    Science.gov (United States)

    Oxley, Jennifer; O'Hern, Steve; Burtt, Duane; Rossiter, Ben

    2017-02-07

    -related injuries that require hospital admission, while also having the highest rate of emergency department presentations when adjusting for age and exposure based on estimates of aggregate walking distances. The study also highlighted that the most common injury sustained from a fall were fractures. The implications of these findings and identification of 'best-practice' within a Safe System context are discussed in terms of enhancements to the physical environment (particularly footpath, kerb and ramp construction and maintenance), implementation of fall hazard assessment and management strategies, and educational programs to highlight the risks for falls and recommend preventative strategies, and overall enhancements of general fall interventions to include falls while walking outside (including exercise interventions). In addition, a number of research and data needs, particularly collection of in-depth data to identify contributory factors and injury outcomes related to falls while walking incidents.

  20. The effects of walking on golf drive performance in two groups of golfers with different skill levels

    Directory of Open Access Journals (Sweden)

    Andrew Green

    2015-04-01

    Full Text Available Although walking is a fundamental part of the game of golf, the effects of walking on the golf shots outcome are largely overlooked. The purpose of the present study was to determine the effects of a hole-to-hole distance walk on the golf drive performance as well as possible physiological contributory factors were evaluated. Twenty-one volunteer golfers were recruited and divided into two groups based on their average round scores: More competitive Golfer (McG ≤88 (n=13 and Irregular Social Golfer (ISG ≥89 (n=8. Drive distance was directly measured. Balance and hand-eye coordination were assessed using a modified stork test and a customized three dimension- al maze. Participants hit 10 golf balls and then walked 500m before repeating the tests. Heart rates of golfers before driving weren’t different between groups, but were elevated within the groups following walking. The McG had longer drives following the walk (p=0.018. The change in the distance was correlated to the change in right leg balance with eyes closed (r=- 0.619 p=0.003. Biomechanical changes were correlated to the change in drive distance (r=0.867 p=0.025. This study shows that an aerobic warm-up prior to a round or small amounts of walking early in a round may be beneficial to golfers of better ability.

  1. Estimation of detection thresholds for redirected walking techniques.

    Science.gov (United States)

    Steinicke, Frank; Bruder, Gerd; Jerald, Jason; Frenz, Harald; Lappe, Markus

    2010-01-01

    In immersive virtual environments (IVEs), users can control their virtual viewpoint by moving their tracked head and walking through the real world. Usually, movements in the real world are mapped one-to-one to virtual camera motions. With redirection techniques, the virtual camera is manipulated by applying gains to user motion so that the virtual world moves differently than the real world. Thus, users can walk through large-scale IVEs while physically remaining in a reasonably small workspace. In psychophysical experiments with a two-alternative forced-choice task, we have quantified how much humans can unknowingly be redirected on physical paths that are different from the visually perceived paths. We tested 12 subjects in three different experiments: (E1) discrimination between virtual and physical rotations, (E2) discrimination between virtual and physical straightforward movements, and (E3) discrimination of path curvature. In experiment E1, subjects performed rotations with different gains, and then had to choose whether the visually perceived rotation was smaller or greater than the physical rotation. In experiment E2, subjects chose whether the physical walk was shorter or longer than the visually perceived scaled travel distance. In experiment E3, subjects estimate the path curvature when walking a curved path in the real world while the visual display shows a straight path in the virtual world. Our results show that users can be turned physically about 49 percent more or 20 percent less than the perceived virtual rotation, distances can be downscaled by 14 percent and upscaled by 26 percent, and users can be redirected on a circular arc with a radius greater than 22 m while they believe that they are walking straight.

  2. Using Optic Flow for the Estimation of Travel Distance

    Directory of Open Access Journals (Sweden)

    Markus Lappe

    2011-05-01

    Full Text Available Much research on optic flow has been concerned with the estimation of heading and the control of the direction of self-motion. In my presentation I will instead focus on a different use of optic flow, namely the estimation of the distance that one has traveled. Optic flow in itself does not provide travel distance, only the combination of distance and speed (time-to-contact is directly available. However, when scaling information from the environment is present, such as the distance to the ground when standing or walking on flat terrain, an integration of the optical velocity can yield ego-speed and travel distance. I will present experiments that show that humans can use optic flow for the estimation of travel distance, but that they often under- and, in some conditions, overestimate a movement's extent. I will then present a model of travel distance estimation from optic flow that is based on leaky path integration.

  3. Comparison of forward walking and backward walking in stroke hemiplegia patients focusing on the paretic side

    Science.gov (United States)

    Makino, Misato; Takami, Akiyoshi; Oda, Atsushi

    2017-01-01

    [Purpose] To investigate the features of backward walking in stroke patients with hemiplegia by focusing on the joint movements and moments of the paretic side, walking speed, stride length, and cadence. [Subjects and Methods] Nine stroke patients performed forward walking and backward walking along a 5-m walkway. Walking speed and stride length were self-selected. Movements were measured using a three-dimensional motion analysis system and a force plate. One walking cycle of the paretic side was analyzed. [Results] Walking speed, stride length, and cadence were significantly lower in backward walking than in forward walking. Peak hip extension was significantly lower in backward walking and peak hip flexion moment, knee extension moment, and ankle dorsiflexion and plantar flexion moments were lower in backward walking. [Conclusion] Unlike forward walking, backward walking requires conscious hip joint extension. Conscious extension of the hip joint is hard for stroke patients with hemiplegia. Therefore, the range of hip joint movement declined in backward walking, and walking speed and stride length also declined. The peak ankle plantar flexion moment was significantly lower in backward walking than in forward walking, and it was hard to generate propulsion power in backward walking. These difficulties also affected the walking speed. PMID:28265136

  4. Encyclopedia of distances

    CERN Document Server

    Deza, Michel Marie

    2016-01-01

    This 4th edition of the leading reference volume on distance metrics is characterized by updated and rewritten sections on some items suggested by experts and readers, as well a general streamlining of content and the addition of essential new topics. Though the structure remains unchanged, the new edition also explores recent advances in the use of distances and metrics for e.g. generalized distances, probability theory, graph theory, coding theory, data analysis. New topics in the purely mathematical sections include e.g. the Vitanyi multiset-metric, algebraic point-conic distance, triangular ratio metric, Rossi-Hamming metric, Taneja distance, spectral semimetric between graphs, channel metrization, and Maryland bridge distance. The multidisciplinary sections have also been supplemented with new topics, including: dynamic time wrapping distance, memory distance, allometry, atmospheric depth, elliptic orbit distance, VLBI distance measurements, the astronomical system of units, and walkability distance. Lea...

  5. Perceptual constancy in judgments of egocentric distance: prevailing binocular information

    Directory of Open Access Journals (Sweden)

    Elton H. Matsushima

    2003-01-01

    Full Text Available Binocular cues were considered the prevailing information on specifying depth since the beginning of vision research. In the present study, two perceptual responses, the classical verbal report and a more recent method, open-loop walking, were used to assess the role of binocular information for egocentric distance perception. In two cue conditions environments, full- and reduced-cue, observers judged and walked egocentric distances of stimuli presented at eye-level, under binocular or monocular viewing. Results indicated perceptual constancy for open-loop walking and binocular responses, as well as poor performances under strong degradation on visual information (reduced-cue under monocular viewing, thus presenting evidence to support the fundamental role of binocular information on perception of egocentric distances. Besides that, visually directed actions could be adequate measures of perceived distance, with a better reliability than verbal report, since they were quite free of intrusion of inferential processes and perceptual tendencies. In addition, reduced head movements, side-to-side as well as back and forth deflexion movements, could have contributed to a near perfect coupling between binocular disparity information and open-loop walking responses.

  6. 378 Average Distance Travelled To School by Primary and ...

    African Journals Online (AJOL)

    User

    2010-10-17

    Oct 17, 2010 ... students walk over one kilometer to school, the outcomes would not be in the .... respondents were the heads of the primary and secondary schools .... maximum distance as low as 28.57% for primary school pupils and 18.75 ...

  7. The metrics of spatial distance traversed during mental imagery

    NARCIS (Netherlands)

    Rinck, M.; Denis, M.

    2004-01-01

    The authors conducted 2 experiments to study the metrics of spatial distance in a mental imagery task. In both experiments, participants first memorized the layout of a building containing 10 rooms with 24 objects. Participants then received mental imagery instructions and imagined how they walked t

  8. Perceptual constancy in judgments of egocentric distance: prevailing binocular information

    Directory of Open Access Journals (Sweden)

    Matsushima Elton H.

    2003-01-01

    Full Text Available Binocular cues were considered the prevailing information on specifying depth since the beginning of vision research. In the present study, two perceptual responses, the classical verbal report and a more recent method, open-loop walking, were used to assess the role of binocular information for egocentric distance perception. In two cue conditions environments, full- and reduced-cue, observers judged and walked egocentric distances of stimuli presented at eye-level, under binocular or monocular viewing. Results indicated perceptual constancy for open-loop walking and binocular responses, as well as poor performances under strong degradation on visual information (reduced-cue under monocular viewing, thus presenting evidence to support the fundamental role of binocular information on perception of egocentric distances. Besides that, visually directed actions could be adequate measures of perceived distance, with a better reliability than verbal report, since they were quite free of intrusion of inferential processes and perceptual tendencies. In addition, reduced head movements, side-to-side as well as back and forth deflexion movements, could have contributed to a near perfect coupling between binocular disparity information and open-loop walking responses.

  9. Why does walking economy improve after weight loss in obese adolescents?

    Science.gov (United States)

    Peyrot, Nicolas; Thivel, David; Isacco, Laurie; Morin, Jean-Benoît; Belli, Alain; Duche, Pascale

    2012-04-01

    This study tested the hypothesis that the increase in walking economy (i.e., decrease in net metabolic rate per kilogram) after weight loss in obese adolescents is induced by a lower metabolic rate required to support the lower body weight and maintain balance during walking. Sixteen obese adolescent boys and girls were tested before and after a weight reduction program. Body composition and oxygen uptake while standing and walking at four preset speeds (0.75, 1, 1.25, and 1.5 m·s⁻¹) and at the preferred speed were quantified. Net metabolic rate and gross metabolic cost of walking-versus-speed relationships were determined. A three-compartment model was used to distinguish the respective parts of the metabolic rate associated with standing (compartment 1), maintaining balance and supporting body weight during walking (compartment 2), and muscle contractions required to move the center of mass and limbs (compartment 3). Standing metabolic rate per kilogram (compartment 1) significantly increased after weight loss, whereas net metabolic rate per kilogram during walking decreased by 9% on average across speeds. Consequently, the gross metabolic cost of walking per unit of distance-versus-speed relationship and hence preferred walking speeds did not change with weight loss. Compartment 2 of the model was significantly lower after weight loss, whereas compartment 3 did not change. The model showed that the improvement in walking economy after weight loss in obese adolescents was likely related to the lower metabolic rate of the isometric muscular contractions required to support the lower body weight and maintain balance during walking. Contrastingly, the part of the total metabolic rate associated with muscle contractions required to move the center of mass and limbs did not seem to be related to the improvement in walking economy in weight-reduced individuals.

  10. Are kinematics of the walk related to the locomotion of a warmblood horse at the trot?

    Science.gov (United States)

    Back, W; Schamhardt, H C; Barneveld, A

    1996-10-01

    Summary In purchase examinations or at studbook selection sales the locomotor apparatus of horses is judged both at walk and trot. To evaluate whether kinematics of the walk are related to the locomotion at the trot, fore and hind limb movements of a group of 24 26-month-old warmbloods were recorded at walk and trot on a treadmill (1.6 and 4 m/s) using a modified CODA-3 gait analysis system. The intralimb coordination patterns at walk and trot were compared, and temporal and spatial variables of these gaits were related. Stride and stance durations (s) were shorter at the trot, while the stance distance (m) and swing duration (s) remained the same. Moreover, the pattern of the joint angle-time curves at walk and trot looked rather similar, though shifted to the left at trot because of the shorter relative stance duration. During the stance phase, the shoulder, stifle and tarsal joints were more flexed throughout, while the carpal and fetlock joints were more maximally extended in the trot than in the walk. In the swing phase, the elbow, carpal, stifle, and tarsal joints were more flexed because of the higher 'operating' speed at the trot compared to the walk. All other kinematic variables at the trot could be predicted from the mean ± 1sd of the values recorded at the walk. Moreover, nearly all kinematic variables at the walk correlated well with those at the trot, while variables indicating gait quality of the walk were similar to the ones identified previously for the trot. In conclusion, kinematics recorded at the walk in a group of horses were similar to and thus predictive for locomotion at the trot providing the decreased stance duration and the increased speed of the trot are taken into consideration.

  11. The average inter-crossing number of equilateral random walks and polygons

    Science.gov (United States)

    Diao, Y.; Dobay, A.; Stasiak, A.

    2005-09-01

    In this paper, we study the average inter-crossing number between two random walks and two random polygons in the three-dimensional space. The random walks and polygons in this paper are the so-called equilateral random walks and polygons in which each segment of the walk or polygon is of unit length. We show that the mean average inter-crossing number ICN between two equilateral random walks of the same length n is approximately linear in terms of n and we were able to determine the prefactor of the linear term, which is a=\\frac{3\\ln 2}{8}\\approx 0.2599 . In the case of two random polygons of length n, the mean average inter-crossing number ICN is also linear, but the prefactor of the linear term is different from that of the random walks. These approximations apply when the starting points of the random walks and polygons are of a distance ρ apart and ρ is small compared to n. We propose a fitting model that would capture the theoretical asymptotic behaviour of the mean average ICN for large values of ρ. Our simulation result shows that the model in fact works very well for the entire range of ρ. We also study the mean ICN between two equilateral random walks and polygons of different lengths. An interesting result is that even if one random walk (polygon) has a fixed length, the mean average ICN between the two random walks (polygons) would still approach infinity if the length of the other random walk (polygon) approached infinity. The data provided by our simulations match our theoretical predictions very well.

  12. Using Degraded Music Quality to Encourage a Health Improving Walking Pace: BeatClearWalker

    Directory of Open Access Journals (Sweden)

    Andreas Komninos

    2015-08-01

    Full Text Available Meeting the target of 8000 steps/day, as recommended by many national governments and health authorities, can provide considerable physical and mental health benefits and is seen as a key target for reducing obesity levels and improving public health. However, to optimize the health benefits, walking should be performed at a “moderate” intensity. While there are numerous mobile fitness applications that monitor distance walked, none directly support walking at this cadence nor has there been any research into live feedback for walking cadence. We present a smartphone fitness application to help users learn how to walk at a moderate cadence and maintain that cadence. We apply real-time audio effects that diminish the audio quality of music when the target walking cadence is not being reached. This provides an immersive and intuitive application that can easily be integrated into everyday life as allows users to walk while listening to their own music and encourages eyes-free interaction. In this paper, we introduce our approach, design, initial lab evaluation and a controlled outdoor study. Results show that using music degradation decreases the number of below-cadence steps, that users felt they worked harder with our player and would use it while exercise walking.

  13. [Comparative analysis of the six-minute walk test in healthy children and adolescents].

    Science.gov (United States)

    Aquino, Evanirso S; Mourão, Flávio A G; Souza, Roberta K V; Glicério, Bráulio M; Coelho, Cristiane C

    2010-01-01

    To perform a comparative analysis of the six-minute walk test in healthy children and adolescents in corridors of 30.5m (100 feet) 20m (65.6 feet) in length. We evaluated 67 participants (36 boys and 31 girls), aged 7 to 14 years old, from public schools of a city in a metropolitan area. All were submitted to four walking tests, two in each of the corridors. The variables analyzed were: walked distance, work rate, mean blood pressure, heart rate and oxygen saturation. Statistical analysis was performed using one-way ANOVA for repeated measures and significance level at ppressure, heart rate and oxygen saturation. The walked distance was not statistically different in the two tests on each corridor. However, the participants covered greater distances on the 30.5m corridor (p<0.05) compared to the best test between corridors. However, this increase was less than 10%. Regarding the cardiac overload and the work rate, there were no significant differences between the corridors. There were differences in walked distance between the corridors, however they were less than 10% with no significant changes in the other measured parameters. Therefore, the 20m corridor had a good reproducibility for the population of this study.

  14. Association between echocardiography derived right ventricular function parameters with cardiac magnetic resonance derived right ventricular ejection fraction and 6-minute walk distance in pulmonary hypertension patients%超声心动图与心脏核磁共振评估肺高血压患者右心室功能的比较

    Institute of Scientific and Technical Information of China (English)

    王臻臻; 杨振文; 万征; 于铁链; 贾莉莉; 杜鑫; 黄灿亮

    2014-01-01

    目的 比较经胸超声心动图(TTE)评价肺高血压(PH)患者右心室功能的各指标与心脏核磁共振成像技术(CMR)测得的右心室射血分数(RVEF)及6 min步行距离(6MWD)的相关性.方法 入选天津医科大学总医院心血管内科2011年3月至2013年3月住院的Ⅰ类和Ⅳ类PH患者40例.入院后行右心导管(RHC)检查,确诊患者在病情稳定及治疗无变化1周内行CMR、TTE、6MWD试验.分别对CMR、TTE、6MWD指标进行相关性分析,并对TTE检测的各指标与CMR获得的RVEF(RVEF-CMR)的相关系数由大到小进行排序.结果 TTE评价右心室功能的指标中,游离壁三尖瓣环收缩期纵向收缩最大速度(S')、游离壁三尖瓣环收缩期峰值位移(TAPSE)、右心室面积变化分数(FAC)、游离壁三尖瓣环等容收缩期加速度(IVA)、心肌做功指数(MPI)与RVEF-CMR均存在相关性,相关系数依次是r =0.69(P <0.001)、r=0.65(P <0.001)、r=0.62(P <0.001)、r=0.43(P =0.006)和r=-0.38(P <0.05).S '、TAPSE、FAC、IVA、MPI与6MWD无相关性.RVEF-CMR与6MWD无相关性.最准确指示RVEF-CMR≤20%的指标是S'<8.79 cm/s,ROC曲线下面积0.92(95% CI:0.72 ~0.84),敏感度0.91,特异度0.80.结论 S'与RVEF相关性最强,S '<8.79 cm/s能准确指示出RVEF≤20%的患者.RVEF-CMR、S '、TAPSE与6MWD均无相关性.%Objective To explore the association between transthoracic echocardiography (TFE) derived right ventricular (RV) function parameters with cardiovascular magnetic resonance imaging (CMR)derived RV ejection fraction (RVEF) and 6 minute walk distance (6MWD) in pulmonary hypertension (PH) patients.Methods A total of 40 PH patients (37 pulmonary artery hypertension (PAH) and 3 chronic thromboembolic pulmonary hypertension (CTEPH)) hospitalized in our department between March 2011 and March 2013 were enrolled in this study.PH diagnosis was established by right heart catheterization and TTE,CMR and 6MWT were performed within one week post TTE

  15. Mechanical design of walking machines.

    Science.gov (United States)

    Arikawa, Keisuke; Hirose, Shigeo

    2007-01-15

    The performance of existing actuators, such as electric motors, is very limited, be it power-weight ratio or energy efficiency. In this paper, we discuss the method to design a practical walking machine under this severe constraint with focus on two concepts, the gravitationally decoupled actuation (GDA) and the coupled drive. The GDA decouples the driving system against the gravitational field to suppress generation of negative power and improve energy efficiency. On the other hand, the coupled drive couples the driving system to distribute the output power equally among actuators and maximize the utilization of installed actuator power. First, we depict the GDA and coupled drive in detail. Then, we present actual machines, TITAN-III and VIII, quadruped walking machines designed on the basis of the GDA, and NINJA-I and II, quadruped wall walking machines designed on the basis of the coupled drive. Finally, we discuss walking machines that travel on three-dimensional terrain (3D terrain), which includes the ground, walls and ceiling. Then, we demonstrate with computer simulation that we can selectively leverage GDA and coupled drive by walking posture control.

  16. Distance Education Council.

    Science.gov (United States)

    Indira Gandhi National Open University, New Delhi (India). Distance Education Council.

    Since its inception in India in 1962, distance education has grown in popularity. The Distance Education Council (DEC) directs distance learning within India's higher education system. The DEC's promotion, coordination, and maintenance of standards for distance education are its three major roles. Its initiatives include grants, support for…

  17. Relationship between self-reported walking ability and objectively assessed gait performance in persons with late effects of polio.

    Science.gov (United States)

    Brogårdh, Christina; Flansbjer, Ulla-Britt; Espelund, Christina; Lexell, Jan

    2013-01-01

    Muscle weakness in the lower limbs and impeded gait performance are common in persons with late effects of polio. To assess self-reported walking ability in persons with late effects of polio and determine the relationship with objectively assessed gait performance. One-hundred and twenty-two individuals with prior polio (65 women and 57 men, mean age 65 [SD ± 9] years) participated in the study. The main outcome measures were: Walk-12 (Swedish version) to assess self-reported walking ability, and Timed "Up & Go", Comfortable Gait Speed, Fast Gait Speed and 6-Minute Walk Tests to assess gait performance objectively. More than 50% of the participants reported limitations (moderately or quite a bit) related to standing or walking, climbing stairs, walking speed and distance, concentration and effort, and gait quality aspects. Half of the participants reported no need to use support when walking indoors or outdoors, but 58% reported that their ability to run was extremely limited. Significant correlations (P Walk-12 and the four gait performance tests (rho -0.66 to 0.63). The strength of the relationship implies that Walk-12 reflects broader dimensions than the objective gait performance tests and can be a complement when the walking ability in persons with late effects of polio is evaluated.

  18. Anti-gravity training improves walking capacity and postural balance in patients with muscular dystrophy

    DEFF Research Database (Denmark)

    Berthelsen, Martin Peter; Husu, Edith; Christensen, Sofie Bouschinger

    2014-01-01

    -gravity treadmill, which offered weight support up to 80% of their body weight. Six minute walking distance, dynamic postural balance, and plasma creatine kinase were assessed 10weeks prior to training, immediately before training and after 10weeks of training. Training elicited an improvement of walking distance...... by 8±2% and dynamic postural balance by 13±4%, indicating an improved physical function. Plasma creatine kinase remained unchanged. These results provide evidence that a combination of aerobic and strength training during anti-gravity has the potential to safely improve functional ability in severely...

  19. Do functional walk tests reflect cardiorespiratory fitness in sub-acute stroke?

    Directory of Open Access Journals (Sweden)

    Bayley Mark T

    2006-09-01

    Full Text Available Abstract Background and purpose The Six-Minute Walk Test (6MWT has been employed as a measure of functional capacity, but its relationship to cardiorespiratory fitness in stroke is not well established. Gait speed measured over short distances is commonly used as an index of walking competency following stroke. We evaluated the relationship between the 6MWT, aerobic fitness (VO2peak and walking competency in sub-acute stroke. Methods Thirty-six individuals (mean age ± SD, 64.6 ± 14.4 years; time post-stroke 16.2 ± 13.3 days were evaluated using the 6MWT (distance, speed, heart rate, a maximal exercise test (VO2peak, heart rate, exercise test duration, and walking competency using a five meter walk (speed, symmetry ratio. Correlation analyses were used to examine the relationships between these outcomes. Results There was a strong correlation between the 6MWT and five meter walk velocity for preferred (r = 0.79 and fast (r = 0.82 speed (p 2peak (r = 0.56, p Conclusion The speed selected during the 6MWT was strongly related to the velocities selected during the five meter walk distance (intermediate to the selected preferred and fast speeds. Although the 6MWT may be challenging to the cardiorespiratory system, it appears to be more strongly influenced by potential limits to walking speed rather than cardiorespiratory capacity. As a result, this test is not, by itself, an adequate measure of aerobic fitness early after stroke.

  20. Training for Distance Teaching through Distance Learning.

    Science.gov (United States)

    Cadorath, Jill; Harris, Simon; Encinas, Fatima

    2002-01-01

    Describes a mixed-mode bachelor degree course in English language teaching at the Universidad Autonoma de Puebla (Mexico) that was designed to help practicing teachers write appropriate distance education materials by giving them the experience of being distance students. Includes a course outline and results of a course evaluation. (Author/LRW)

  1. Reliability and Validity of Bilateral Ankle Accelerometer Algorithms for Activity Recognition and Walking Speed After Stroke

    Science.gov (United States)

    Dobkin, Bruce H.; Xu, Xiaoyu; Batalin, Maxim; Thomas, Seth; Kaiser, William

    2015-01-01

    Background and Purpose Outcome measures of mobility for large stroke trials are limited to timed walks for short distances in a laboratory, step counters and ordinal scales of disability and quality of life. Continuous monitoring and outcome measurements of the type and quantity of activity in the community would provide direct data about daily performance, including compliance with exercise and skills practice during routine care and clinical trials. Methods Twelve adults with impaired ambulation from hemiparetic stroke and 6 healthy controls wore triaxial accelerometers on their ankles. Walking speed for repeated outdoor walks was determined by machine-learning algorithms and compared to a stopwatch calculation of speed for distances not known to the algorithm. The reliability of recognizing walking, exercise, and cycling by the algorithms was compared to activity logs. Results A high correlation was found between stopwatch-measured outdoor walking speed and algorithm-calculated speed (Pearson coefficient, 0.98; P=0.001) and for repeated measures of algorithm-derived walking speed (P=0.01). Bouts of walking >5 steps, variations in walking speed, cycling, stair climbing, and leg exercises were correctly identified during a day in the community. Compared to healthy subjects, those with stroke were, as expected, more sedentary and slower, and their gait revealed high paretic-to-unaffected leg swing ratios. Conclusions Test–retest reliability and concurrent and construct validity are high for activity pattern-recognition Bayesian algorithms developed from inertial sensors. This ratio scale data can provide real-world monitoring and outcome measurements of lower extremity activities and walking speed for stroke and rehabilitation studies. PMID:21636815

  2. Single and Dual Task Walking

    Directory of Open Access Journals (Sweden)

    Natalie de Bruin

    2010-01-01

    Full Text Available This study explored the viability and efficacy of integrating cadence-matched, salient music into a walking intervention for patients with Parkinson's disease (PD. Twenty-two people with PD were randomised to a control (CTRL, n=11 or experimental (MUSIC, n=11 group. MUSIC subjects walked with an individualised music playlist three times a week for the intervention period. Playlists were designed to meet subject's musical preferences. In addition, the tempo of the music closely matched (±10–15 bpm the subject's preferred cadence. CTRL subjects continued with their regular activities during the intervention. The effects of training accompanied by “walking songs” were evaluated using objective measures of gait score. The MUSIC group improved gait velocity, stride time, cadence, and motor symptom severity following the intervention. This is the first study to demonstrate that music listening can be safely implemented amongst PD patients during home exercise.

  3. Greedy adaptive walks on a correlated fitness landscape.

    Science.gov (United States)

    Park, Su-Chan; Neidhart, Johannes; Krug, Joachim

    2016-05-21

    We study adaptation of a haploid asexual population on a fitness landscape defined over binary genotype sequences of length L. We consider greedy adaptive walks in which the population moves to the fittest among all single mutant neighbors of the current genotype until a local fitness maximum is reached. The landscape is of the rough mount Fuji type, which means that the fitness value assigned to a sequence is the sum of a random and a deterministic component. The random components are independent and identically distributed random variables, and the deterministic component varies linearly with the distance to a reference sequence. The deterministic fitness gradient c is a parameter that interpolates between the limits of an uncorrelated random landscape (c=0) and an effectively additive landscape (c→∞). When the random fitness component is chosen from the Gumbel distribution, explicit expressions for the distribution of the number of steps taken by the greedy walk are obtained, and it is shown that the walk length varies non-monotonically with the strength of the fitness gradient when the starting point is sufficiently close to the reference sequence. Asymptotic results for general distributions of the random fitness component are obtained using extreme value theory, and it is found that the walk length attains a non-trivial limit for L→∞, different from its values for c=0 and c=∞, if c is scaled with L in an appropriate combination.

  4. Biased random walks on Kleinberg's spatial networks

    Science.gov (United States)

    Pan, Gui-Jun; Niu, Rui-Wu

    2016-12-01

    We investigate the problem of the particle or message that travels as a biased random walk toward a target node in Kleinberg's spatial network which is built from a d-dimensional (d = 2) regular lattice improved by adding long-range shortcuts with probability P(rij) ∼rij-α, where rij is the lattice distance between sites i and j, and α is a variable exponent. Bias is represented as a probability p of the packet to travel at every hop toward the node which has the smallest Manhattan distance to the target node. We study the mean first passage time (MFPT) for different exponent α and the scaling of the MFPT with the size of the network L. We find that there exists a threshold probability pth ≈ 0.5, for p ≥pth the optimal transportation condition is obtained with an optimal transport exponent αop = d, while for 0 pth, and increases with L less than a power law and get close to logarithmical law for 0 complex network with a highly efficient structure for navigation although nodes hold null local information with a relatively large probability, which gives a powerful evidence for the reason why many real networks' navigability have small world property.

  5. Self-interacting random walks

    CERN Document Server

    Peres, Yuval; Sousi, Perla

    2012-01-01

    Let $\\mu_1,... \\mu_k$ be $d$-dimensional probability measures in $\\R^d$ with mean 0. At each step we choose one of the measures based on the history of the process and take a step according to that measure. We give conditions for transience of such processes and also construct examples of recurrent processes of this type. In particular, in dimension 3 we give the complete picture: every walk generated by two measures is transient and there exists a recurrent walk generated by three measures.

  6. Pedagogies of the Walking Dead

    Directory of Open Access Journals (Sweden)

    Michael A. Peters

    2016-04-01

    Full Text Available This paper investigates the trope of the zombie and the recent upsurge in popular culture surrounding the figure of the zombie described as the “walking dead”. We investigate this trope and figure as a means of analyzing the “pedagogy of the walking dead” with particular attention to the crisis of education in the era of neoliberal capitalism. In particular we examine the professionalization and responsibilization of teachers in the new regulative environment and ask whether there is any room left for the project of critical education.

  7. Square lattice self-avoiding walks and biased differential approximants

    Science.gov (United States)

    Jensen, Iwan

    2016-10-01

    The model of self-avoiding lattice walks and the asymptotic analysis of power-series have been two of the major research themes of Tony Guttmann. In this paper we bring the two together and perform a new analysis of the generating functions for the number of square lattice self-avoiding walks and some of their metric properties such as the mean-square end-to-end distance. The critical point x c for self-avoiding walks is known to a high degree of accuracy and we utilise this knowledge to undertake a new numerical analysis of the series using biased differential approximants. The new method is major advance in asymptotic power-series analysis in that it allows us to bias differential approximants to have a singularity of order q at x c. When biasing at x c with q≥slant 2 the analysis yields a very accurate estimate for the critical exponent γ =1.343 7500(3) thus confirming the conjectured exact value γ =43/32 to eight significant digits and removing a long-standing minor discrepancy between exact and numerical results. The analysis of the mean-square end-to-end distance yields ν =0.750 0002(4) thus confirming the exact value ν =3/4 to seven significant digits. Dedicated to Tony Guttmann on the occasion of his 70th birthday.

  8. Encyclopedia of distances

    CERN Document Server

    Deza, Michel Marie

    2014-01-01

    This updated and revised third edition of the leading reference volume on distance metrics includes new items from very active research areas in the use of distances and metrics such as geometry, graph theory, probability theory and analysis. Among the new topics included are, for example, polyhedral metric space, nearness matrix problems, distances between belief assignments, distance-related animal settings, diamond-cutting distances, natural units of length, Heidegger’s de-severance distance, and brain distances. The publication of this volume coincides with intensifying research efforts into metric spaces and especially distance design for applications. Accurate metrics have become a crucial goal in computational biology, image analysis, speech recognition and information retrieval. Leaving aside the practical questions that arise during the selection of a ‘good’ distance function, this work focuses on providing the research community with an invaluable comprehensive listing of the main available di...

  9. Determining an influencing area affecting walking speed on footpath: A case study of a footpath in CBD Bangkok, Thailand

    Science.gov (United States)

    Tipakornkiat, Chalat; Limanond, Thirayoot; Kim, Hyunmyung

    2012-11-01

    Intuitively, the crowd density in front of a pedestrian will affect his walking speed along a footpath. Nevertheless, the size of the influencing area affecting walking speed has rarely been scrutinized in the past. This study attempts to determine the distance in front of pedestrians that principally affects their walking speed under normal conditions, using a case study of a footpath in Bangkok. We recorded pedestrian activities along a test section of 20 m, with an effective walking width of 2.45 m in the morning and at noon. The morning dataset was extracted for analyzing various influencing distances, ranging from 1 to 20 m in front of the pedestrian. The bi-directional walking speed-pedestrian density models were developed, for each tested distance, using linear regression analysis. It was found that an influencing length in the range of 5-8 m yields the highest correlation coefficients. In the case of high density conditions, the walking speed of the equally-split flow (50:50) was found to be higher than other proportional flow analyzed. The finding has useful implications on the improvement of the walking simulations in mesoscopic models.

  10. The Long Road of Pain: Chronic Pain Increases Perceived Distance

    Science.gov (United States)

    Witt, Jessica K.; Linkenauger, Sally A.; Bakdash, Jonathan Z.; Augustyn, Jason S.; Cook, Andrew J.; Proffitt, Dennis R.

    2011-01-01

    Spatial perception is sensitive to the energetic costs required to perform intended actions. For example, hills look steeper to people who are fatigued or burdened by a heavy load. Similarly, perceived distance is also influenced by the energy required to walk or throw to a target. Such experiments demonstrate that perception is a function, not just of optical information, but also of the perceiver’s potential to act and the energetic costs associated with the intended action. In the current paper, we expand on the notion of “cost” by examining perceived distance in patients diagnosed with chronic pain, a multifactorial disease, which is experienced while walking. We found that chronic pain patients perceive target distances to be farther away than a control group. These results indicate the physical, and perhaps emotional, costs of chronic pain affect spatial perceptions. PMID:18949471

  11. Accelerometry-enabled measurement of walking performance with a robotic exoskeleton: a pilot study.

    Science.gov (United States)

    Lonini, Luca; Shawen, Nicholas; Scanlan, Kathleen; Rymer, William Z; Kording, Konrad P; Jayaraman, Arun

    2016-03-31

    Clinical scores for evaluating walking skills with lower limb exoskeletons are often based on a single variable, such as distance walked or speed, even in cases where a host of features are measured. We investigated how to combine multiple features such that the resulting score has high discriminatory power, in particular with few patients. A new score is introduced that allows quantifying the walking ability of patients with spinal cord injury when using a powered exoskeleton. Four spinal cord injury patients were trained to walk over ground with the ReWalk™ exoskeleton. Body accelerations during use of the device were recorded by a wearable accelerometer and 4 features to evaluate walking skills were computed. The new score is the Gaussian naïve Bayes surprise, which evaluates patients relative to the features' distribution measured in 7 expert users of the ReWalk™. We compared our score based on all the features with a standard outcome measure, which is based on number of steps only. All 4 patients improved over the course of training, as their scores trended towards the expert users' scores. The combined score (Gaussian naïve surprise) was considerably more discriminative than the one using only walked distance (steps). At the end of training, 3 out of 4 patients were significantly different from the experts, according to the combined score (p exoskeleton. Testing this approach with other features and more subjects remains as future work.

  12. Stereo vision with distance and gradient recognition

    Science.gov (United States)

    Kim, Soo-Hyun; Kang, Suk-Bum; Yang, Tae-Kyu

    2007-12-01

    Robot vision technology is needed for the stable walking, object recognition and the movement to the target spot. By some sensors which use infrared rays and ultrasonic, robot can overcome the urgent state or dangerous time. But stereo vision of three dimensional space would make robot have powerful artificial intelligence. In this paper we consider about the stereo vision for stable and correct movement of a biped robot. When a robot confront with an inclination plane or steps, particular algorithms are needed to go on without failure. This study developed the recognition algorithm of distance and gradient of environment by stereo matching process.

  13. Age-related differences in walking stability

    National Research Council Canada - National Science Library

    Menz, Hylton B; Lord, Stephen R; Fitzpatrick, Richard C

    2003-01-01

    .... to evaluate acceleration patterns at the head and pelvis in young and older subjects when walking on a level and an irregular walking surface, in order to develop an understanding of how ageing...

  14. Brisk Walk May Help Sidestep Heart Disease

    Science.gov (United States)

    ... fullstory_162978.html Brisk Walk May Help Sidestep Heart Disease In just 10 weeks, cholesterol, blood pressure and ... at moderate intensity may lower the risk of heart disease, a small study suggests. "We know walking is ...

  15. Minnesota Walk-In Access Sites

    Data.gov (United States)

    Minnesota Department of Natural Resources — The Minnesota Walk-In Access site (WIA) GIS data represents areas of private land that have been made open to the public for the purpose of walk-in (foot travel)...

  16. Walking Shoes: Features and Fit

    Science.gov (United States)

    ... be snug, not tight. If you're a woman with wide feet, consider men's or boys' shoes, which are cut a bit larger through the heel and the ball of the foot. Walk in the shoes before buying them. They should feel comfortable right away. Make sure your heel fits snugly in ...

  17. Walking Tips for Older Adults

    Science.gov (United States)

    ... the most ppular form of exercise among older adults and it's a great choice. What can walking do for you? strengthen muscles help prevent weight gain lower risks of heart disease, stroke, diabetes, and osteoporosis improve balance lower the likelihood of falling If ...

  18. Efficient quantum walk on a quantum processor

    OpenAIRE

    Qiang, Xiaogang; Loke, Thomas; Montanaro, Ashley; Aungskunsiri, Kanin; Zhou, Xiao-Qi; O'Brien, Jeremy; Wang, Jingbo; Matthews, Jonathan

    2016-01-01

    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 ef...

  19. Einstein's random walk and thermal diffusion

    OpenAIRE

    2013-01-01

    Thermal diffusion has been studied for over 150 years. Despite of the long history and the increasing importance of the phenomenon, the physics of thermal diffusion remains poorly understood. In this paper Ludwig's thermal diffusion is explained using Einstein's random walk. The only new structure added is the spatial heterogeneity of the random walk to reflect the temperature gradient of thermal diffusion. Hence, the walk length and the walk speed are location dependent functions in this pap...

  20. Visual Saliency and Attention as Random Walks on Complex Networks

    CERN Document Server

    Costa, L F

    2006-01-01

    The unmatched versatility of vision in mammals is totally dependent on purposive eye movements and selective attention guided by saliencies in the presented images. The current article shows how concepts and tools from the areas of random walks, Markov chains, complex networks and artificial image analysis can be naturally combined in order to provide a unified and biologically plausible model for saliency detection and visual attention, which become indistinguishable in the process. Images are converted into complex networks by considering pixels as nodes while connections are established in terms of fields of influence defined by visual features such as tangent fields induced by luminance contrasts, distance, and size. Random walks are performed on such networks in order to emulate attentional shifts and even eye movements in the case of large shapes, and the frequency of visits to each node is conveniently obtained from the eigenequation defined by the stochastic matrix associated to the respectively drive...

  1. Scaling analysis of random walks with persistence lengths: Application to self-avoiding walks

    Science.gov (United States)

    Granzotti, C. R. F.; Martinez, A. S.; da Silva, M. A. A.

    2016-05-01

    We develop an approach for performing scaling analysis of N -step random walks (RWs). The mean square end-to-end distance, , is written in terms of inner persistence lengths (IPLs), which we define by the ensemble averages of dot products between the walker's position and displacement vectors, at the j th step. For RW models statistically invariant under orthogonal transformations, we analytically introduce a relation between and the persistence length, λN, which is defined as the mean end-to-end vector projection in the first step direction. For self-avoiding walks (SAWs) on 2D and 3D lattices we introduce a series expansion for λN, and by Monte Carlo simulations we find that λ∞ is equal to a constant; the scaling corrections for λN can be second- and higher-order corrections to scaling for . Building SAWs with typically 100 steps, we estimate the exponents ν0 and Δ1 from the IPL behavior as function of j . The obtained results are in excellent agreement with those in the literature. This shows that only an ensemble of paths with the same length is sufficient for determining the scaling behavior of , being that the whole information needed is contained in the inner part of the paths.

  2. Distances from Planetary Nebulae

    CERN Document Server

    Ciardullo, R

    2003-01-01

    The [O III] 5007 planetary nebula luminosity function (PNLF) occupies an important place on the extragalactic distance ladder. Since it is the only method that is applicable to all the large galaxies of the Local Supercluster, it is uniquely useful for cross-checking results and linking the Population I and Population II distance scales. We review the physics underlying the method, demonstrate its precision, and illustrate its value by comparing its distances to distances obtained from Cepheids and the Surface Brightness Fluctuation (SBF) method. We use the Cepheid and PNLF distances to 13 galaxies to show that the metallicity dependence of the PNLF cutoff is in excellent agreement with that predicted from theory, and that no additional systematic corrections are needed for either method. However, when we compare the Cepheid-calibrated PNLF distance scale with the Cepheid-calibrated SBF distance scale, we find a significant offset: although the relative distances of both methods are in excellent agreement, th...

  3. Developmental Continuity? Crawling, Cruising, and Walking

    Science.gov (United States)

    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…

  4. A Comparison of Walking Rates Between Wild and Zoo African Elephants.

    Science.gov (United States)

    Miller, Lance J; Chase, Michael J; Hacker, Charlotte E

    2016-01-01

    With increased scrutiny surrounding the welfare of elephants in zoological institutions, it is important to have empirical evidence on their current welfare status. If elephants are not receiving adequate exercise, it could lead to obesity, which can lead to many issues including acyclicity and potentially heart disease. The goal of the current study was to compare the walking rates of elephants in the wild versus elephants in zoos to determine if elephants are walking similar distances relative to their wild counterparts. Eleven wild elephants throughout different habitats and locations in Botswana were compared to 8 elephants at the San Diego Zoo Safari Park. Direct comparisons revealed no significant difference in average walking rates of zoo elephants when compared with wild elephants. These results suggest that elephants at the San Diego Zoo Safari Park walk similar rates to those of wild elephants and may be meeting their exercise needs.

  5. A generalized evidence distance

    Institute of Scientific and Technical Information of China (English)

    Hongming Mo; Xi Lu; Yong Deng

    2016-01-01

    How to efficiently measure the distance between two basic probability assignments (BPAs) is an open issue. In this paper, a new method to measure the distance between two BPAs is proposed, based on two existing measures of evidence distance. The new proposed method is comprehen-sive and generalized. Numerical examples are used to ilus-trate the effectiveness of the proposed method.

  6. Are the average gait speeds during the 10meter and 6minute walk tests redundant in Parkinson disease?

    Science.gov (United States)

    Duncan, Ryan P; Combs-Miller, Stephanie A; McNeely, Marie E; Leddy, Abigail L; Cavanaugh, James T; Dibble, Leland E; Ellis, Terry D; Ford, Matthew P; Foreman, K Bo; Earhart, Gammon M

    2017-02-01

    We investigated the relationships between average gait speed collected with the 10Meter Walk Test (Comfortable and Fast) and 6Minute Walk Test (6MWT) in 346 people with Parkinson disease (PD) and how the relationships change with increasing disease severity. Pearson correlation and linear regression analyses determined relationships between 10Meter Walk Test and 6MWT gait speed values for the entire sample and for sub-samples stratified by Hoehn & Yahr (H&Y) stage I (n=53), II (n=141), III (n=135) and IV (n=17). We hypothesized that redundant tests would be highly and significantly correlated (i.e. r>0.70, pMeter Walk Test (r=0.75) and Fast 10Meter Walk Test (r=0.79) gait speed, with 56% and 62% of the variance in 6MWT gait speed explained, respectively. The regression model of 6MWT gait speed predicted by Comfortable 10 Meter Walk gait speed produced slope and intercept values near 1 and 0, respectively, especially for participants in H&Y stages II-IV. In contrast, slope and intercept values were further from 1 and 0, respectively, for the Fast 10Meter Walk Test. Comfortable 10 Meter Walk Test and 6MWT gait speeds appeared to be redundant in people with moderate to severe PD, suggesting the Comfortable 10 Meter Walk Test can be used to estimate 6MWT distance in this population.

  7. Active quantum walks: a framework for quantum walks with adiabatic quantum evolution

    Science.gov (United States)

    Wu, Nan; Song, Fangmin; Li, Xiangdong

    2016-05-01

    We study a new methodology for quantum walk based algorithms. Different from the passive quantum walk, in which a walker is guided by a quantum walk procedure, the new framework that we developed allows the walker to move by an adiabatic procedure of quantum evolution, as an active way. The use of this active quantum walk is helpful to develop new quantum walk based searching and optimization algorithms.

  8. Walking...A Step in the Right Direction!

    Science.gov (United States)

    ... parts: Warm up by walking slowly. Increase your speed to a brisk walk. Brisk walking means walking fast enough to raise your heart ... go faster and farther. Add hills or some stairs to make your walks more challenging. Review the sample walking plan that follows for an idea of how ...

  9. Walking, orthoses and physical effort in a Swedish population with arthrogryposis.

    Science.gov (United States)

    Eriksson, Marie; Villard, Li; Bartonek, Asa

    2014-08-01

    Excessive movements during walking have been observed by gait analysis in children with arthrogryposis (AMC) using orthoses compared to children using only shoes. The aim of this study was to evaluate energy expenditure and functional exercise capacity in children with AMC. Twenty-four children with AMC and 25 typically developing (TD) children underwent oxygen measurement and the 6-minute walk test (6MWT). Children were divided into AMC1 using knee-ankle-foot orthoses with locked knee joints (KAFO-LK); AMC2 KAFOs with open knee joints (KAFO-O) or ankle-foot orthoses (AFO); and AMC3 using shoes. The net non-dimensional oxygen cost (NNcost) was lower in TD (0.308) than in AMC2 (0.455, n = 10) (p = 0.002). There were no differences in the net non-dimensional consumption (NNconsumption) or normalised walking velocity. The lowest NNconsumption (0.082), NNcost (0.385) and normalised walking velocity (0.214) were found in AMC1 (n = 3), but no statistical calculation was performed. In the 6MWT, both AMC2 (402.7, n = 11) and AMC3 (476.8, n = 10) walked shorter distances (m) than TD (565.1) (p KAFOs or AFOs (AMC2) had higher energy effort represented by significantly higher NNcost than TD, whereas AMC children requiring only shoes (AMC3) did not differ significantly from TD. To maintain the NNconsumption at an acceptable level, children using locked KAFOs (AMC1) slowed down their walking velocity. Compared to TD, the exercise capacity was lower in children with AMC using open KAFOs or AFOs and shoes, represented by lower walking velocity and shorter distance walked during the 6MWT.

  10. Tourists consuming distance

    DEFF Research Database (Denmark)

    Larsen, Gunvor Riber

    The environmental impact of tourism mobility is linked to the distances travelled in order to reach a holiday destination, and with tourists travelling more and further than previously, an understanding of how the tourists view the distance they travel across becomes relevant. Based on interviews...... contribute to an understanding of how it is possible to change tourism travel behaviour towards becoming more sustainable. How tourists 'consume distance' is discussed, from the practical level of actually driving the car or sitting in the air plane, to the symbolic consumption of distance that occurs when...... travelling on holiday becomes part of a lifestyle and a social positioning game. Further, different types of tourist distance consumers are identified, ranging from the reluctant to the deliberate and nonchalant distance consumers, who display very differing attitudes towards the distance they all travel...

  11. Learning string edit distance

    CERN Document Server

    Ristad, E S; Ristad, Eric Sven; Yianilos, Peter N.

    1996-01-01

    In many applications, it is necessary to determine the similarity of two strings. A widely-used notion of string similarity is the edit distance: the minimum number of insertions, deletions, and substitutions required to transform one string into the other. In this report, we provide a stochastic model for string edit distance. Our stochastic model allows us to learn a string edit distance function from a corpus of examples. We illustrate the utility of our approach by applying it to the difficult problem of learning the pronunciation of words in conversational speech. In this application, we learn a string edit distance with one fourth the error rate of the untrained Levenshtein distance. Our approach is applicable to any string classification problem that may be solved using a similarity function against a database of labeled prototypes. Keywords: string edit distance, Levenshtein distance, stochastic transduction, syntactic pattern recognition, prototype dictionary, spelling correction, string correction, ...

  12. Interface Simulation Distances

    Directory of Open Access Journals (Sweden)

    Pavol Černý

    2012-10-01

    Full Text Available The classical (boolean notion of refinement for behavioral interfaces of system components is the alternating refinement preorder. In this paper, we define a distance for interfaces, called interface simulation distance. It makes the alternating refinement preorder quantitative by, intuitively, tolerating errors (while counting them in the alternating simulation game. We show that the interface simulation distance satisfies the triangle inequality, that the distance between two interfaces does not increase under parallel composition with a third interface, and that the distance between two interfaces can be bounded from above and below by distances between abstractions of the two interfaces. We illustrate the framework, and the properties of the distances under composition of interfaces, with two case studies.

  13. Feasibility and Reliability of Two Different Walking Tests in People With Severe Intellectual and Sensory Disabilities

    NARCIS (Netherlands)

    Waninge, A.; Evenhuis, I. J.; van Wijck, R.; van der Schans, C. P.

    2011-01-01

    Background The purpose of this study is to describe feasibility and test-retest reliability of the six-minute walking distance test (6MWD) and an adapted shuttle run test (aSRT) in persons with severe intellectual and sensory (multiple) disabilities. Materials and Methods Forty-seven persons with se

  14. Biased random walks on multiplex networks

    CERN Document Server

    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...

  15. High on Walking : Conquering Everyday Life.

    Science.gov (United States)

    Martinsen, Bente; Haahr, Anita; Dreyer, Pia; Norlyk, Annelise

    2017-01-01

    The aim of this study is to discuss the meaning of walking impairment among people who have previously been able to walk on their own. The study is based on findings from three different life situations: older people recovering after admission in intermediate care, people who have lost a leg, and people who live with Parkinson's disease. The analysis of the data is inspired by Paul Ricoeur's philosophy of interpretation. Four themes were identified: (a) I feel high in two ways; (b) Walking has to be automatic; (c) Every Monday, I walk with the girls in the park; and (d) I dream of walking along the street without sticks and things like that. The findings demonstrate that inability to walk profoundly affected the participants' lives. Other problems seemed small by comparison because walking impairment was at the same time experienced as a concrete physical limit and an existential deficit.

  16. City Walks and Tactile Experience

    Directory of Open Access Journals (Sweden)

    Mădălina Diaconu

    2011-01-01

    Full Text Available This paper is an attempt to develop categories of the pedestrian’s tactile and kinaesthetic experience of the city. The beginning emphasizes the haptic qualities of surfaces and textures, which can be “palpated” visually or experienced by walking. Also the lived city is three-dimensional; its corporeal depth is discussed here in relation to the invisible sewers, protuberant profiles, and the formal diversity of roofscapes. A central role is ascribed in the present analysis to the formal similarities between the representation of the city by walking through it and the representation of the tactile form of objects. Additional aspects of the “tactile” experience of the city in a broad sense concern the feeling of their rhythms and the exposure to weather conditions. Finally, several aspects of contingency converge in the visible age of architectural works, which record traces of individual and collective histories.

  17. Groups, graphs and random walks

    CERN Document Server

    Salvatori, Maura; Sava-Huss, Ecaterina

    2017-01-01

    An accessible and panoramic account of the theory of random walks on groups and graphs, stressing the strong connections of the theory with other branches of mathematics, including geometric and combinatorial group theory, potential analysis, and theoretical computer science. This volume brings together original surveys and research-expository papers from renowned and leading experts, many of whom spoke at the workshop 'Groups, Graphs and Random Walks' celebrating the sixtieth birthday of Wolfgang Woess in Cortona, Italy. Topics include: growth and amenability of groups; Schrödinger operators and symbolic dynamics; ergodic theorems; Thompson's group F; Poisson boundaries; probability theory on buildings and groups of Lie type; structure trees for edge cuts in networks; and mathematical crystallography. In what is currently a fast-growing area of mathematics, this book provides an up-to-date and valuable reference for both researchers and graduate students, from which future research activities will undoubted...

  18. Quantum walk on a cylinder

    CERN Document Server

    Bru, Luis A; Di Molfetta, Giuseppe; Pérez, Armando; Roldán, Eugenio; Silva, Fernando

    2016-01-01

    We consider the 2D alternate quantum walk on a cylinder. We concentrate on the study of the motion along the open dimension, in the spirit of looking at the closed coordinate as a small or "hidden" extra dimension. If one starts from localized initial conditions on the lattice, the dynamics of the quantum walk that is obtained after tracing out the small dimension shows the contribution of several components, which can be understood from the study of the dispersion relations for this problem. In fact, these components originate from the contribution of the possible values of the quasi-momentum in the closed dimension. In the continuous space-time limit, the different components manifest as a set of Dirac equations, with each quasi-momentum providing the value of the corresponding mass. We briefly discuss the possible link of these ideas to the simulation of high energy physical theories that include extra dimensions.

  19. Effects of walking velocity on vertical head and body movements during locomotion

    Science.gov (United States)

    Hirasaki, E.; Moore, S. T.; Raphan, T.; Cohen, B.

    1999-01-01

    Trunk and head movements were characterized over a wide range of walking speeds to determine the relationship between stride length, stepping frequency, vertical head translation, pitch rotation of the head, and pitch trunk rotation as a function of gait velocity. Subjects (26-44 years old) walked on a linear treadmill at velocities of 0.6-2.2 m/s. The head and trunk were modeled as rigid bodies, and rotation and translation were determined using a video-based motion analysis system. At walking speeds up to 1.2 m/s there was little head pitch movement in space, and the head pitch relative to the trunk was compensatory for trunk pitch. As walking velocity increased, trunk pitch remained approximately invariant, but a significant head translation developed. This head translation induced compensatory head pitch in space, which tended to point the head at a fixed point in front of the subject that remained approximately invariant with regard to walking speed. The predominant frequency of head translation and rotation was restricted to a narrow range from 1.4 Hz at 0.6 m/s to 2.5 Hz at 2.2 m/s. Within the range of 0.8-1.8 m/s, subjects tended to increase their stride length rather than step frequency to walk faster, maintaining the predominant frequency of head movement at close to 2.0 Hz. At walking speeds above 1.2 m/s, head pitch in space was highly coherent with, and compensatory for, vertical head translation. In the range 1.2-1.8 m/s, the power spectrum of vertical head translation was the most highly tuned, and the relationship between walking speed and head and trunk movements was the most linear. We define this as an optimal range of walking velocity with regard to head-trunk coordination. The coordination of head and trunk movement was less coherent at walking velocities below 1.2 m/s and above 1.8 m/s. These results suggest that two mechanisms are utilized to maintain a stable head fixation distance over the optimal range of walking velocities. The relative

  20. Effects of walking velocity on vertical head and body movements during locomotion

    Science.gov (United States)

    Hirasaki, E.; Moore, S. T.; Raphan, T.; Cohen, B.

    1999-01-01

    Trunk and head movements were characterized over a wide range of walking speeds to determine the relationship between stride length, stepping frequency, vertical head translation, pitch rotation of the head, and pitch trunk rotation as a function of gait velocity. Subjects (26-44 years old) walked on a linear treadmill at velocities of 0.6-2.2 m/s. The head and trunk were modeled as rigid bodies, and rotation and translation were determined using a video-based motion analysis system. At walking speeds up to 1.2 m/s there was little head pitch movement in space, and the head pitch relative to the trunk was compensatory for trunk pitch. As walking velocity increased, trunk pitch remained approximately invariant, but a significant head translation developed. This head translation induced compensatory head pitch in space, which tended to point the head at a fixed point in front of the subject that remained approximately invariant with regard to walking speed. The predominant frequency of head translation and rotation was restricted to a narrow range from 1.4 Hz at 0.6 m/s to 2.5 Hz at 2.2 m/s. Within the range of 0.8-1.8 m/s, subjects tended to increase their stride length rather than step frequency to walk faster, maintaining the predominant frequency of head movement at close to 2.0 Hz. At walking speeds above 1.2 m/s, head pitch in space was highly coherent with, and compensatory for, vertical head translation. In the range 1.2-1.8 m/s, the power spectrum of vertical head translation was the most highly tuned, and the relationship between walking speed and head and trunk movements was the most linear. We define this as an optimal range of walking velocity with regard to head-trunk coordination. The coordination of head and trunk movement was less coherent at walking velocities below 1.2 m/s and above 1.8 m/s. These results suggest that two mechanisms are utilized to maintain a stable head fixation distance over the optimal range of walking velocities. The relative

  1. Predicting metabolic rate during level and uphill outdoor walking using a low-cost GPS receiver.

    Science.gov (United States)

    de Müllenheim, Pierre-Yves; Dumond, Rémy; Gernigon, Marie; Mahé, Guillaume; Lavenu, Audrey; Bickert, Sandrine; Prioux, Jacques; Noury-Desvaux, Bénédicte; Le Faucheur, Alexis

    2016-08-01

    The objective of this study was to assess the accuracy of using speed and grade data obtained from a low-cost global positioning system (GPS) receiver to estimate metabolic rate (MR) during level and uphill outdoor walking. Thirty young, healthy adults performed randomized outdoor walking for 6-min periods at 2.0, 3.5, and 5.0 km/h and on three different grades: 1) level walking, 2) uphill walking on a 3.7% mean grade, and 3) uphill walking on a 10.8% mean grade. The reference MR [metabolic equivalents (METs) and oxygen uptake (V̇o2)] values were obtained using a portable metabolic system. The speed and grade were obtained using a low-cost GPS receiver (1-Hz recording). The GPS grade (Δ altitude/distance walked) was calculated using both uncorrected GPS altitude data and GPS altitude data corrected with map projection software. The accuracy of predictions using reference speed and grade (actual[SPEED/GRADE]) data was high [R(2) = 0.85, root-mean-square error (RMSE) = 0.68 MET]. The accuracy decreased when GPS speed and uncorrected grade (GPS[UNCORRECTED]) data were used, although it remained substantial (R(2) = 0.66, RMSE = 1.00 MET). The accuracy was greatly improved when the GPS speed and corrected grade (GPS[CORRECTED]) data were used (R(2) = 0.82, RMSE = 0.79 MET). Published predictive equations for walking MR were also cross-validated using actual or GPS speed and grade data when appropriate. The prediction accuracy was very close when either actual[SPEED/GRADE] values or GPS[CORRECTED] values (for level and uphill combined) or GPS speed values (for level walking only) were used. These results offer promising research and clinical applications related to the assessment of energy expenditure during free-living walking.

  2. WALKING CAPACITY AND FALLS-EFFICACY CORRELATES WITH PARTICIPATION RESTRICTION IN INDIVIDUALS WITH CHRONIC STROKE: A CROSS SECTIONAL STUDY

    Directory of Open Access Journals (Sweden)

    Neelam Nayak

    2015-02-01

    Full Text Available Background: Mobility impairments seen after Stroke impact walking speed, endurance and balance. Almost all the individuals with Stroke have fear of fall. The physical impairments in balance and gait along with individual’s perception about his/her own abilities to maintain balance might have an impact on level of activity and participation in the community. The association of these variables with recovery of Stroke has been well studied. However, it is currently unknown which of these variables are most associated with activity and participation in the community. This study aimed to identify the correlation of walking capacity and perception of fall with activity & participation. Methods: 30 Subjects were assessed for - walking capacity (6 minute walk test & Self-efficacy for falls (Modified Falls Efficacy scale. Level of Activity Limitation (AL & Participation Restriction (PR was graded on validated ICF Measure of Participation and Activities. (IMPACT-S Results: Data was analyzed using Pearson's correlation coefficient & regression model. Walking distance and Falls-efficacy is significantly correlated (r=-0.751 and -0.683, respectively with Participation restriction. Walking distance correlated with Activity Limitation (r=-0.714 significantly. Falls efficacy has a correlation coefficient of -0.642 with Activity Limitation. When put into Regression models, Walking Capacity & Gait Velocity was found to be independently associated with AL &PR. Conclusion: There is significant relationship between falls self-efficacy, walking capacity and Post-stroke activity & participation. Participation can be impacted by factors such as self-motivation and confidence about one's balance abilities. This is reflected by the correlation between falls efficacy and participation. Physical parameters such as the distance walked can contribute to participating in the community, and can predict variation in AL-PR

  3. Turbulent pair dispersion as a continuous-time random walk

    CERN Document Server

    Thalabard, Simon; Bec, Jeremie

    2014-01-01

    The phenomenology of turbulent relative dispersion is revisited. A heuristic scenario is proposed, in which pairs of tracers undergo a succession of independent ballistic separations during time intervals whose lengths fluctuate. This approach suggests that the logarithm of the distance between tracers self-averages and performs a continuous-time random walk. This leads to specific predictions for the probability distribution of separations, that differ from those obtained using scale-dependent eddy-diffusivity models (e.g. in the framework of Richardson's approach). Such predictions are tested against high-resolution simulations and shed new lights on the explosive separation between tracers.

  4. The QWalk simulator of quantum walks

    Science.gov (United States)

    Marquezino, F. L.; Portugal, R.

    2008-09-01

    Several research groups are giving special attention to quantum walks recently, because this research area have been used with success in the development of new efficient quantum algorithms. A general simulator of quantum walks is very important for the development of this area, since it allows the researchers to focus on the mathematical and physical aspects of the research instead of deviating the efforts to the implementation of specific numerical simulations. In this paper we present QWalk, a quantum walk simulator for one- and two-dimensional lattices. Finite two-dimensional lattices with generic topologies can be used. Decoherence can be simulated by performing measurements or by breaking links of the lattice. We use examples to explain the usage of the software and to show some recent results of the literature that are easily reproduced by the simulator. Program summaryProgram title: QWalk Catalogue identifier: AEAX_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEAX_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: GNU General Public Licence No. of lines in distributed program, including test data, etc.: 10 010 No. of bytes in distributed program, including test data, etc.: 172 064 Distribution format: tar.gz Programming language: C Computer: Any computer with a C compiler that accepts ISO C99 complex arithmetic (recent versions of GCC, for instance). Pre-compiled Windows versions are also provided Operating system: The software should run in any operating system with a recent C compiler. Successful tests were performed in Linux and Windows RAM: Less than 10 MB were required for a two-dimensional lattice of size 201×201. About 400 MB, for a two-dimensional lattice of size 1601×1601 Classification: 16.5 Nature of problem: Classical simulation of discrete quantum walks in one- and two-dimensional lattices. Solution method: Iterative approach without explicit representation of

  5. [A new procedure for the estimation of physical fitness of patients during clinical rehabilitation using the 6-minute-walk-test].

    Science.gov (United States)

    Marek, W; Marek, E; Vogel, P; Mückenhoff, K; Kotschy-Lang, N

    2008-11-01

    AIMS OF THE INVESTIGATION: The 6-minute-walk-test (6-MW) is an effective tool for measuring physical fitness in elderly patients. The increased walking distance is taken as a parameter for improved physical conditions. Frequently an unaltered walking distance is found after clinical treatment, but heart rate is significantly lower in the second challenge, indicating an improved physical fitness. This positive effect is not recognised when only the walking distance is analysed. An analysis of the 6-MW test was performed on 263 patients before and after 3 - 4 weeks clinical rehabilitation. In a control group of 26 patients 6-MW was repeated after recovery at the beginning and the end of the clinical treatment. Instrumented by a mobile pulse oximeter for recording oxygen saturation and heart rate, patients were instructed to walk as fast as they can do during 6 minutes. Measurements were performed every 30 seconds and printed out. Two new parameters, efficiency (E = S/f (C)), the ratio of distance and mean heart rate, and the theoretical increase in walking distance (S (z) = Delta f (C1)/Delta f (C2) x S (2) - S (1)) were introduced and tested. S (z) = theoretical increase in distance, Delta f (C1) = difference in heart rate at rest and mean heart rate at steady state during the first walk test with distance, S1. Delta f (C2), and S2 are measured during the second walk. Thus, the increase in distance is calculated under the assumption that the second walk test would have been performed by the patient with the same difference in heart rate that he/she achieved in the first walk. The patient groups walked 353 +/- 80 m at 106 +/- 14.3 beats/min in the 1st. 6-MW and 368 +/- 76.9 m at a heart rate of 105 +/- 14.0 beats/min in the final test. The increase of the walking distance was most significant in patients with shorter distances in the 1st 6-MW. A significant increase in the walking distance and in efficiency was found in patients with shorter walking distances or

  6. Neural basis of stimulus-angle-dependent motor control of wind-elicited walking behavior in the cricket Gryllus bimaculatus.

    Science.gov (United States)

    Oe, Momoko; Ogawa, Hiroto

    2013-01-01

    Crickets exhibit oriented walking behavior in response to air-current stimuli. Because crickets move in the opposite direction from the stimulus source, this behavior is considered to represent 'escape behavior' from an approaching predator. However, details of the stimulus-angle-dependent control of locomotion during the immediate phase, and the neural basis underlying the directional motor control of this behavior remain unclear. In this study, we used a spherical-treadmill system to measure locomotory parameters including trajectory, turn angle and velocity during the immediate phase of responses to air-puff stimuli applied from various angles. Both walking direction and turn angle were correlated with stimulus angle, but their relationships followed different rules. A shorter stimulus also induced directionally-controlled walking, but reduced the yaw rotation in stimulus-angle-dependent turning. These results suggest that neural control of the turn angle requires different sensory information than that required for oriented walking. Hemi-severance of the ventral nerve cords containing descending axons from the cephalic to the prothoracic ganglion abolished stimulus-angle-dependent control, indicating that this control required descending signals from the brain. Furthermore, we selectively ablated identified ascending giant interneurons (GIs) in vivo to examine their functional roles in wind-elicited walking. Ablation of GI8-1 diminished control of the turn angle and decreased walking distance in the initial response. Meanwhile, GI9-1b ablation had no discernible effect on stimulus-angle-dependent control or walking distance, but delayed the reaction time. These results suggest that the ascending signals conveyed by GI8-1 are required for turn-angle control and maintenance of walking behavior, and that GI9-1b is responsible for rapid initiation of walking. It is possible that individual types of GIs separately supply the sensory signals required to control wind

  7. Relationships between walking and percentiles of adiposity inolder and younger men

    Energy Technology Data Exchange (ETDEWEB)

    Williams, Paul T.

    2005-06-01

    To assess the relationship of weekly walking distance to percentiles of adiposity in elders (age {ge} 75 years), seniors (55 {le} age <75 years), middle-age men (35 {le} age <55 years), and younger men (18 {le} age <35 years old). Cross-sectional analyses of baseline questionnaires from 7,082 male participants of the National Walkers Health Study. The walkers BMIs were inversely and significantly associated with walking distance (kg/m{sup 2} per km/wk) in elders (slope {+-} SE: -0.032 {+-} 0.008), seniors (-0.045 {+-} 0.005), and middle-aged men (-0.037 {+-} 0.007), as were their waist circumferences (-0.091 {+-} 0.025, -0.045 {+-} 0.005, and -0.091 {+-} 0.015 cm per km/wk, respectively), and these slopes remained significant when adjusted statistically for reported weekly servings of meat, fish, fruit, and alcohol. The declines in BMI associated with walking distance were greater at the higher than lower percentiles of the BMI distribution. Specifically, compared to the decline at the 10th BMI percentile, the decline in BMI at the 90th percentile was 5.1-fold greater in elders, 5.9-fold greater in seniors, and 6.7-fold greater in middle-age men. The declines in waist circumference associated with walking distance were also greater among men with broader waistlines. Exercise-induced weight loss (or self-selection) causes an inverse relationship between adiposity and walking distance in men 35 and older that is substantially greater among fatter men.

  8. Keeping Your Distance

    Directory of Open Access Journals (Sweden)

    Glen Gatin

    2013-06-01

    Full Text Available This analysis began with inquiries into the substantive area of distance education using the classic grounded theory method. Analysis revealed a pattern of problemsolving behavior, from which the theory Keeping Your Distance emerged. The theory is an integrated set of concepts referring to the conscious and unconscious strategiesthat people use to regulate distance, physical and representative, in their everyday lives. Strategies are used to control physical, emotional, and psychological realities and to conserve personal energy in interactions with individuals and/or institutions.For all social interactions, people use a personalized algorithm of engagement that mitigates conditions and consequences and preserves optimal distance. Keeping Your Distance provides a theoretical starting point for considerations of the changing notions of distance. In part, these changes have been brought about bydevelopments in the fields of Information and Communication Technology (ICT and online social networking.

  9. Can aerobic treadmill training reduce the effort of walking and fatigue in people with multiple sclerosis: a pilot study.

    Science.gov (United States)

    Newman, M A; Dawes, H; van den Berg, M; Wade, D T; Burridge, J; Izadi, H

    2007-01-01

    Impaired mobility in multiple sclerosis (MS) is associated with high-energy costs and effort when walking, gait abnormalities, poor endurance and fatigue. This repeated measures trial with blinded assessments investigated the effect of treadmill walking at an aerobic training intensity in 16 adults with MS. The intervention consisted of 12 sessions of up to 30 minutes treadmill training (TT), at 55-85% of age-predicted maximum heart rate. The primary outcome measure was walking effort, measured by oxygen consumption (mL/kg per metre), during treadmill walking at comfortable walking speed (CWS). Associated changes in gait parameters using the 'Gait-Rite' mat, 10-m time and 2-minute distance, and Fatigue Severity Scale were examined. Following training, oxygen consumption decreased at rest (P = 0.008), CWS increased (P = 0.002), and 10-m times (P = 0.032) and walking endurance (P = 0.020) increased. At increased CWS, oxygen consumption decreased (P = 0.020), with a decreased time spent in stance in the weaker leg (P = 0.034), and a greater stride distance with the stronger leg (P = 0.044). Reported fatigue levels remained the same. Aerobic TT presents the opportunity to alter a motor skill and reduce the effort of walking, whilst addressing cardiovascular de-conditioning, thereby, potentially reducing effort and fatigue for some people with MS.

  10. Segment lengths influence hill walking strategies.

    Science.gov (United States)

    Sheehan, Riley C; Gottschall, Jinger S

    2014-08-22

    Segment lengths are known to influence walking kinematics and muscle activity patterns. During level walking at the same speed, taller individuals take longer, slower strides than shorter individuals. Based on this, we sought to determine if segment lengths also influenced hill walking strategies. We hypothesized that individuals with longer segments would display more joint flexion going uphill and more extension going downhill as well as greater lateral gastrocnemius and vastus lateralis activity in both directions. Twenty young adults of varying heights (below 155 cm to above 188 cm) walked at 1.25 m/s on a level treadmill as well as 6° and 12° up and downhill slopes while we collected kinematic and muscle activity data. Subsequently, we ran linear regressions for each of the variables with height, leg, thigh, and shank length. Despite our population having twice the anthropometric variability, the level and hill walking patterns matched closely with previous studies. While there were significant differences between level and hill walking, there were few hill walking variables that were correlated with segment length. In support of our hypothesis, taller individuals had greater knee and ankle flexion during uphill walking. However, the majority of the correlations were between tibialis anterior and lateral gastrocnemius activities and shank length. Contrary to our hypothesis, relative step length and muscle activity decreased with segment length, specifically shank length. In summary, it appears that individuals with shorter segments require greater propulsion and toe clearance during uphill walking as well as greater braking and stability during downhill walking.

  11. Numerical distance protection

    CERN Document Server

    Ziegler, Gerhard

    2011-01-01

    Distance protection provides the basis for network protection in transmission systems and meshed distribution systems. This book covers the fundamentals of distance protection and the special features of numerical technology. The emphasis is placed on the application of numerical distance relays in distribution and transmission systems.This book is aimed at students and engineers who wish to familiarise themselves with the subject of power system protection, as well as the experienced user, entering the area of numerical distance protection. Furthermore it serves as a reference guide for s

  12. Determining asymmetry of roll-over shapes in prosthetic walking

    Directory of Open Access Journals (Sweden)

    Carolin Curtze, MSc

    2011-12-01

    Full Text Available How does the inherent asymmetry of the locomotor system in people with lower-limb amputation affect the ankle-foot roll-over shape of prosthetic walking? In a single-case design, we evaluated the walking patterns of six people with lower-limb amputation (3 transtibial and 3 transfemoral and three matched nondisabled controls. We analyzed the walking patterns in terms of roll-over characteristics and spatial and temporal factors. We determined the level of asymmetry by roll-over shape comparison (root-mean-square distance as well as differences in radius of curvature. In addition, we calculated ratios to determine spatial and temporal asymmetries and described different aspects of asymmetry of roll-over shapes. All participants showed some level of asymmetry in roll-over shape, even the nondisabled controls. Furthermore, we found good intralimb reproducibility for the group as a whole. With respect to spatial and temporal factors, the participants with transtibial amputation had a quite symmetrical gait pattern, while the gait in the participants with transfemoral amputation was more asymmetrical. The individual ankle-foot roll-over shapes provide additional insight into the marked individual adjustments occurring during the stance phase of the nondisabled limb. The two methods we present are suitable for determining asymmetry of roll-over shapes; both methods should be used complementarily.

  13. Modulation of head movement control in humans during treadmill walking

    Science.gov (United States)

    Mulavara, Ajitkumar P.; Verstraete, Mary C.; Bloomberg, Jacob J.

    2002-01-01

    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/s (20 s trials) while fixing their gaze on a centrally located earth-fixed target positioned at a distance of 2 m from their eyes. The net and relative angular motions of the head about the three axes of rotations, as well as the corresponding values for the moments acting on it relative to the trunk during the gait cycle were quantified and used as measures of coordination. The average net moment, as well as the average moments about the different axes were significantly different (Pphases of the gait cycle. However, the average net angular displacement as well as the average angular displacement about the axial rotation axis of the head relative to the trunk was maintained uniform (P>0.01) throughout the gait cycle. The average angular displacement about the lateral bending axis was significantly increased (Pphase while that about the flexion-extension axis was significantly decreased (Pgait 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 fixation of targets during walking.

  14. Modulation of head movement control in humans during treadmill walking

    Science.gov (United States)

    Mulavara, Ajitkumar P.; Verstraete, Mary C.; Bloomberg, Jacob J.

    2002-01-01

    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/s (20 s trials) while fixing their gaze on a centrally located earth-fixed target positioned at a distance of 2 m from their eyes. The net and relative angular motions of the head about the three axes of rotations, as well as the corresponding values for the moments acting on it relative to the trunk during the gait cycle were quantified and used as measures of coordination. The average net moment, as well as the average moments about the different axes were significantly different (Plow/no impact phases of the gait cycle. However, the average net angular displacement as well as the average angular displacement about the axial rotation axis of the head relative to the trunk was maintained uniform (P>0.01) throughout the gait cycle. The average angular displacement about the lateral bending axis was significantly increased (Phead 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 fixation of targets during walking.

  15. Random walk of passive tracers among randomly moving obstacles

    CERN Document Server

    Gori, Matteo; Floriani, Elena; Nardecchia, Ilaria; Pettini, Marco

    2016-01-01

    Background: This study is mainly motivated by the need of understanding how the diffusion behaviour of a biomolecule (or even of a larger object) is affected by other moving macromolecules, organelles, and so on, inside a living cell, whence the possibility of understanding whether or not a randomly walking biomolecule is also subject to a long-range force field driving it to its target. Method: By means of the Continuous Time Random Walk (CTRW) technique the topic of random walk in random environment is here considered in the case of a passively diffusing particle in a crowded environment made of randomly moving and interacting obstacles. Results: The relevant physical quantity which is worked out is the diffusion cofficient of the passive tracer which is computed as a function of the average inter-obstacles distance. Coclusions: The results reported here suggest that if a biomolecule, let us call it a test molecule, moves towards its target in the presence of other independently interacting molecules, its m...

  16. Walk-Startup of a Two-Legged Walking Mechanism

    Science.gov (United States)

    Babković, Kalman; Nagy, László; Krklješ, Damir; Borovac, Branislav

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

  17. Walking after incomplete spinal cord injury using an implanted FES system: a case report.

    Science.gov (United States)

    Hardin, Elizabeth; Kobetic, Rudi; Murray, Lori; Corado-Ahmed, Michelle; Pinault, Gilles; Sakai, Jonathan; Bailey, Stephanie Nogan; Ho, Chester; Triolo, Ronald J

    2007-01-01

    Implanted functional electrical stimulation (FES) systems for walking are experimentally available to individuals with incomplete spinal cord injury (SCI); however, data on short-term therapeutic and functional outcomes are limited. The goal of this study was to quantify therapeutic and functional effects of an implanted FES system for walking after incomplete cervical SCI. After robotic-assisted treadmill training and overground gait training maximized his voluntary function, an individual with incomplete SCI (American Spinal Injury Association grade C, cervical level 6-7) who could stand volitionally but not step was surgically implanted with an 8-channel receiver stimulator and intramuscular electrodes. Electrodes were implanted bilaterally, recruiting iliopsoas, vastus intermedius and lateralis, tensor fasciae latae, tibialis anterior, and peroneus longus muscles. Twelve weeks of training followed limited activity post-surgery. Customized stimulation patterns addressed gait deficits via an external control unit. The system was well-tolerated and reliable. After the 12-week training, maximal walking distance increased (from 14 m to 309 m), maximal walking speed was 10 times greater (from 0.02 m/s to 0.20 m/s), and physiological cost index was 5 times less (from 44.4 beats/m to 8.6 beats/m). Voluntary locomotor function was unchanged. The implanted FES system was well-tolerated, reliable, and supplemented function, allowing the participant limited community ambulation. Physiological effort decreased and maximal walking distance increased dramatically over 12 weeks.

  18. System overview and walking dynamics of a passive dynamic walking robot with flat feet

    Directory of Open Access Journals (Sweden)

    Xinyu Liu

    2015-12-01

    Full Text Available The concept of “passive dynamic walking robot” refers to the robot that can walk down a shallow slope stably without any actuation and control which shows a limit cycle during walking. By adding actuation at some joints, the passive dynamic walking robot can walk stably on level ground and exhibit more versatile gaits than fully passive robot, namely, the “limit cycle walker.” In this article, we present the mechanical structures and control system design for a passive dynamic walking robot with series elastic actuators at hip joint and ankle joints. We built a walking model that consisted of an upper body, knee joints, and flat feet and derived its walking dynamics that involve double stance phases in a walking cycle based on virtual power principle. The instant just before impact was chosen as the start of one step to reduce the number of independent state variables. A numerical simulation was implemented by using MATLAB, in which the proposed passive dynamic walking model could walk stably down a shallow slope, which proves that the derived walking dynamics are correct. A physical passive robot prototype was built finally, and the experiment results show that by only simple control scheme the passive dynamic robot could walk stably on level ground.

  19. A Branching Random Walk Seen from the Tip

    Science.gov (United States)

    Brunet, Éric; Derrida, Bernard

    2011-05-01

    We show that all the time-dependent statistical properties of the rightmost points of a branching Brownian motion can be extracted from the traveling wave solutions of the Fisher-KPP equation. The distribution of all the distances between the rightmost points has a long time limit which can be understood as the delay of the Fisher-KPP traveling waves when the initial condition is modified. The limiting measure exhibits the surprising property of superposability: the statistical properties of the distances between the rightmost points of the union of two realizations of the branching Brownian motion shifted by arbitrary amounts are the same as those of a single realization. We discuss the extension of our results to more general branching random walks.

  20. Full revivals in 2D quantum walks

    Energy Technology Data Exchange (ETDEWEB)

    Stefanak, M; Jex, I [Department of Physics, FJFI CVUT v Praze, Brehova 7, 115 19 Praha 1-Stare Mesto (Czech Republic); Kollar, B; Kiss, T, E-mail: martin.stefanak@fjfi.cvut.c [Department of Quantum Optics and Quantum Information, Research Institute for Solid State Physics and Optics, Hungarian Academy of Sciences, Konkoly-Thege M. u. 29-33, H-1121 Budapest (Hungary)

    2010-09-01

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

  1. Comparison of Random Waypoint & Random Walk Mobility Model under DSR, AODV & DSDV MANET Routing Protocols

    CERN Document Server

    Aslam, Muhammad Zaheer

    2011-01-01

    Mobile Adhoc Network is a kind of wireless ad hoc network where nodes are connected wirelessly and the network is self configuring. MANET may work in a standalone manner or may be a part of another network. In this paper we have compared Random Walk Mobility Model and Random Waypoint Mobility Model over two reactive routing protocols Dynamic Source Routing (DSR) and Adhoc On-Demand Distance Vector Routing (AODV) protocol and one Proactive routing protocol Distance Sequenced Distance Vector Routing (DSDV) Our analysis showed that DSR, AODV & DSDV under Random Walk and Random Way Point Mobility models have similar results for similar inputs however as the pause time increases so does the difference in performance rises. They show that their motion, direction, angle of direction, speed is same under both mobility models. We have made their analysis on packet delivery ratio, throughput and routing overhead. We have tested them with different criteria like different number of nodes, speed and different maximum...

  2. Normalized information distance

    NARCIS (Netherlands)

    Vitányi, P.M.B.; Balbach, F.J.; Cilibrasi, R.L.; Li, M.; Emmert-Streib, F.; Dehmer, M.

    2009-01-01

    The normalized information distance is a universal distance measure for objects of all kinds. It is based on Kolmogorov complexity and thus uncomputable, but there are ways to utilize it. First, compression algorithms can be used to approximate the Kolmogorov complexity if the objects have a string

  3. Normalized information distance

    NARCIS (Netherlands)

    Vitányi, P.M.B.; Balbach, F.J.; Cilibrasi, R.L.; Li, M.

    2008-01-01

    The normalized information distance is a universal distance measure for objects of all kinds. It is based on Kolmogorov complexity and thus uncomputable, but there are ways to utilize it. First, compression algorithms can be used to approximate the Kolmogorov complexity if the objects have a string

  4. Incremental Distance Transforms (IDT)

    NARCIS (Netherlands)

    Schouten, Theo E.; van den Broek, Egon; Erçil, A.; Çetin, M.; Boyer, K.; Lee, S.-W.

    2010-01-01

    A new generic scheme for incremental implementations of distance transforms (DT) is presented: Incremental Distance Transforms (IDT). This scheme is applied on the cityblock, Chamfer, and three recent exact Euclidean DT (E2DT). A benchmark shows that for all five DT, the incremental implementation r

  5. ORDERED WEIGHTED DISTANCE MEASURE

    Institute of Scientific and Technical Information of China (English)

    Zeshui XU; Jian CHEN

    2008-01-01

    The aim of this paper is to develop an ordered weighted distance (OWD) measure, which is thegeneralization of some widely used distance measures, including the normalized Hamming distance, the normalized Euclidean distance, the normalized geometric distance, the max distance, the median distance and the min distance, etc. Moreover, the ordered weighted averaging operator, the generalized ordered weighted aggregation operator, the ordered weighted geometric operator, the averaging operator, the geometric mean operator, the ordered weighted square root operator, the square root operator, the max operator, the median operator and the min operator axe also the special cases of the OWD measure. Some methods depending on the input arguments are given to determine the weights associated with the OWD measure. The prominent characteristic of the OWD measure is that it can relieve (or intensify) the influence of unduly large or unduly small deviations on the aggregation results by assigning them low (or high) weights. This desirable characteristic makes the OWD measure very suitable to be used in many actual fields, including group decision making, medical diagnosis, data mining, and pattern recognition, etc. Finally, based on the OWD measure, we develop a group decision making approach, and illustrate it with a numerical example.

  6. Duty and Distance

    NARCIS (Netherlands)

    C. Binder (C.); C. Heilmann (Conrad)

    2017-01-01

    markdownabstractEver since the publication of Peter Singer’s article ‘‘Famine, Affluence, and Morality’’ has the question of whether the (geographical) distance to people in need affects our moral duties towards them been a hotly debated issue. Does geographical distance affect our moral duties?

  7. Biomechanics of Distance Running.

    Science.gov (United States)

    Cavanagh, Peter R., Ed.

    Contributions from researchers in the field of running mechanics are included in the 13 chapters of this book. The following topics are covered: (1) "The Mechanics of Distance Running: A Historical Perspective" (Peter Cavanagh); (2) "Stride Length in Distance Running: Velocity, Body Dimensions, and Added Mass Effects" (Peter Cavanagh, Rodger…

  8. Distance Learning Environment Demonstration.

    Science.gov (United States)

    1996-11-01

    The Distance Learning Environment Demonstration (DLED) was a comparative study of distributed multimedia computer-based training using low cost high...measurement. The DLED project provides baseline research in the effective use of distance learning and multimedia communications over a wide area ATM/SONET

  9. Duty and Distance

    NARCIS (Netherlands)

    C. Binder (C.); C. Heilmann (Conrad)

    2017-01-01

    markdownabstractEver since the publication of Peter Singer’s article ‘‘Famine, Affluence, and Morality’’ has the question of whether the (geographical) distance to people in need affects our moral duties towards them been a hotly debated issue. Does geographical distance affect our moral

  10. Oral amino acids in elderly subjects: effect on myocardial function and walking capacity.

    Science.gov (United States)

    Scognamiglio, Roldano; Piccolotto, Roberto; Negut, Christian; Tiengo, Antonio; Avogaro, Angelo

    2005-01-01

    With advancing age the risk of developing serious nutritional deficiencies increases, and disturbances to the actions of insulin and insulin-like growth factor, coupled with reduced protein/amino acid (AA) intake, impair protein synthesis in muscles. To assess the effects of administering oral AAs on walking capacity and perceived walking impairment, isometric muscular strength, and myocardial function at rest and during isometric exercise. One hundred elderly subjects (aged >65 years) with reduced physical activity were randomized to receive an oral AA mixture (12 g/day) or placebo for 3 months. At baseline and after 3 months of therapy we assessed physical capacity with the 6-min walk test, and perceived physical impairment with the walking impairment questionnaire (WIQ); we assessed maximal isometric muscular strength of the right hand with a handgrip dynamometer, and left ventricular ejection fraction (LVEF) using quantitative two-dimensional echocardiography at rest and during acute overload. Three months of AA treatment resulted in significant increases in 6-min walk distance (268.8 +/- 34.9 vs. 212 +/- 40 m, p speed: 72.2 +/- 14.4 vs. 52.8 +/- 12%, p stairs: 98.2 +/- 24 vs. 72.4 +/- 22%, p walking capacity. Copyright 2005 S. Karger AG, Basel

  11. A Simple Exoskeleton That Assists Plantarflexion Can Reduce the Metabolic Cost of Human Walking

    Science.gov (United States)

    Malcolm, Philippe; Derave, Wim; Galle, Samuel; De Clercq, Dirk

    2013-01-01

    Background Even though walking can be sustained for great distances, considerable energy is required for plantarflexion around the instant of opposite leg heel contact. Different groups attempted to reduce metabolic cost with exoskeletons but none could achieve a reduction beyond the level of walking without exoskeleton, possibly because there is no consensus on the optimal actuation timing. The main research question of our study was whether it is possible to obtain a higher reduction in metabolic cost by tuning the actuation timing. Methodology/Principal Findings We measured metabolic cost by means of respiratory gas analysis. Test subjects walked with a simple pneumatic exoskeleton that assists plantarflexion with different actuation timings. We found that the exoskeleton can reduce metabolic cost by 0.18±0.06 W kg−1 or 6±2% (standard error of the mean) (p = 0.019) below the cost of walking without exoskeleton if actuation starts just before opposite leg heel contact. Conclusions/Significance The optimum timing that we found concurs with the prediction from a mathematical model of walking. While the present exoskeleton was not ambulant, measurements of joint kinetics reveal that the required power could be recycled from knee extension deceleration work that occurs naturally during walking. This demonstrates that it is theoretically possible to build future ambulant exoskeletons that reduce metabolic cost, without power supply restrictions. PMID:23418524

  12. A simple exoskeleton that assists plantarflexion can reduce the metabolic cost of human walking.

    Directory of Open Access Journals (Sweden)

    Philippe Malcolm

    Full Text Available BACKGROUND: Even though walking can be sustained for great distances, considerable energy is required for plantarflexion around the instant of opposite leg heel contact. Different groups attempted to reduce metabolic cost with exoskeletons but none could achieve a reduction beyond the level of walking without exoskeleton, possibly because there is no consensus on the optimal actuation timing. The main research question of our study was whether it is possible to obtain a higher reduction in metabolic cost by tuning the actuation timing. METHODOLOGY/PRINCIPAL FINDINGS: We measured metabolic cost by means of respiratory gas analysis. Test subjects walked with a simple pneumatic exoskeleton that assists plantarflexion with different actuation timings. We found that the exoskeleton can reduce metabolic cost by 0.18±0.06 W kg(-1 or 6±2% (standard error of the mean (p = 0.019 below the cost of walking without exoskeleton if actuation starts just before opposite leg heel contact. CONCLUSIONS/SIGNIFICANCE: The optimum timing that we found concurs with the prediction from a mathematical model of walking. While the present exoskeleton was not ambulant, measurements of joint kinetics reveal that the required power could be recycled from knee extension deceleration work that occurs naturally during walking. This demonstrates that it is theoretically possible to build future ambulant exoskeletons that reduce metabolic cost, without power supply restrictions.

  13. Changes in the built environment and changes in the amount of walking over time: longitudinal results from the multi-ethnic study of atherosclerosis.

    Science.gov (United States)

    Hirsch, Jana A; Moore, Kari A; Clarke, Philippa J; Rodriguez, Daniel A; Evenson, Kelly R; Brines, Shannon J; Zagorski, Melissa A; Diez Roux, Ana V

    2014-10-15

    Lack of longitudinal research hinders causal inference on the association between the built environment and walking. In the present study, we used data from 6,027 adults in the Multi-Ethnic Study of Atherosclerosis who were 45-84 years of age at baseline to investigate the association of neighborhood built environment with trends in the amount of walking between 2000 and 2012. Walking for transportation and walking for leisure were assessed at baseline and at 3 follow-up visits (median follow-up = 9.15 years). Time-varying built environment measures (measures of population density, land use, number of destinations, bus access, and street connectivity) were created using geographic information systems. We used linear mixed models to estimate the associations between baseline levels of and a change in each built environment feature and a change in the frequency of walking. After adjustment for potential confounders, we found that higher baseline levels of population density, area zoned for retail, social destinations, walking destinations, and street connectivity were associated with greater increases in walking for transportation over time. Higher baseline levels of land zoned for residential use and distance to buses were associated with less pronounced increases (or decreases) in walking for transportation over time. Increases in the number of social destinations, the number of walking destinations, and street connectivity over time were associated with greater increases in walking for transportation. Higher baseline levels of both land zoned for retail and walking destinations were associated with greater increases in leisure walking, but no changes in built environment features were associated with leisure walking. The creation of mixed-use, dense developments may encourage adults to incorporate walking for transportation into their everyday lives.

  14. Estimating distances from parallaxes

    Science.gov (United States)

    Astraatmadja, Tri L.; Bailer-Jones, Coryn

    2017-01-01

    In astrometric surveys such as Gaia and LSST, parallaxes will be measured for about a billion stars, but zero distances will be measured. Distances must be inferred from the parallaxes, and the common inference practice is by inverting the parallax. This, however, is only appropriate when there is no noise present. As noise will always be present and most stars in future surveys will have non-negligible fractional parallax uncertainties, we must treat distance estimation as an inference problem. The usage of prior assumptions become unavoidable. In this talk I will present a method on how to infer distances using Bayesian inference. Three minimalists, isotropic priors are used, as well an anisotropic prior derived from the observability of stars in a Milky Way model. The performance of these priors are investigated using a simulated Gaia-like catalogue. Recent results of distance estimation using the parallaxes of 2 million Gaia DR1 stars will also be discussed.

  15. Normalized Information Distance

    CERN Document Server

    Vitanyi, Paul M B; Cilibrasi, Rudi L; Li, Ming

    2008-01-01

    The normalized information distance is a universal distance measure for objects of all kinds. It is based on Kolmogorov complexity and thus uncomputable, but there are ways to utilize it. First, compression algorithms can be used to approximate the Kolmogorov complexity if the objects have a string representation. Second, for names and abstract concepts, page count statistics from the World Wide Web can be used. These practical realizations of the normalized information distance can then be applied to machine learning tasks, expecially clustering, to perform feature-free and parameter-free data mining. This chapter discusses the theoretical foundations of the normalized information distance and both practical realizations. It presents numerous examples of successful real-world applications based on these distance measures, ranging from bioinformatics to music clustering to machine translation.

  16. Quantum walks public key cryptographic system

    OpenAIRE

    Vlachou, C; Rodrigues, J.; Mateus, P.; Paunković, N.; Souto, A.

    2016-01-01

    Quantum Cryptography is a rapidly developing field of research that benefits from the properties of Quantum Mechanics in performing cryptographic tasks. Quantum walks are a powerful model for quantum computation and very promising for quantum information processing. In this paper, we present a quantum public-key cryptographic system based on quantum walks. In particular, in the proposed protocol the public key is given by a quantum state generated by performing a quantum walk. We show that th...

  17. Quantum random walks - an introductory overview

    CERN Document Server

    Kempe, J

    2003-01-01

    This article aims to provide an introductory survey on quantum random walks. Starting from a physical effect to illustrate the main ideas we will introduce quantum random walks, review some of their properties and outline their striking differences to classical walks. We will touch upon both physical effects and computer science applications, introducing some of the main concepts and language of present day quantum information science in this context. We will mention recent developments in this new area and outline some open questions.

  18. Random Walk Smooth Transition Autoregressive Models

    OpenAIRE

    2004-01-01

    This paper extends the family of smooth transition autoregressive (STAR) models by proposing a specification in which the autoregressive parameters follow random walks. The random walks in the parameters can capture structural change within a regime switching framework, but in contrast to the time varying STAR (TV-STAR) speciifcation recently introduced by Lundbergh et al (2003), structural change in our random walk STAR (RW-STAR) setting follows a stochastic process rather than a determinist...

  19. Measuring sidewalk distances using Google Earth

    Directory of Open Access Journals (Sweden)

    Janssen Ian

    2012-03-01

    Full Text Available Abstract Background Physical activity is an important determinant of health. Walking is the most common physical activity performed by adults and the presence of sidewalks along roads is a determinant of walking. Geographic information systems (GIS can be used to measure sidewalks; however, GIS sidewalk data are difficult to access. The purpose of this study was to present a new GIS method for measuring the distance and coverage of sidewalks along roadways. Methods The new method contains three stages. Stage 1 involves calculating the distance of all road segments within the region of interest (e.g., neighborhood, extracting geospatial information on these road segments, and saving this information as a Google Earth file. This stage was performed in ArcGIS software. Stage 2 involves opening the extracted road segment geospatial data in Google Earth, visually examining road segments to see if they contain sidewalks, and deleting road segments without sidewalks. Stage 3 involves importing the modified road geospatial data into ArcGIS and calculating the length of road segments with sidewalks. The new method was tested in 315 sites across Canada. Each site consisted of a one km radius circular buffer surrounding a school. Results A detailed, step-by-step protocol is provided in the paper. The length of road segments with sidewalks in the testing sites ranged from 0.00 to 55.05 km (median 16.20 km. When expressed relative to the length of all road segments, the length of road segments with sidewalks ranged from 0% to 100% (median 53%. By comparison to urban testing sites, rural sites had shorter sidewalk lengths and a smaller proportion of the roads had sidewalk coverage. Conclusion This study provides a new GIS protocol that researchers can use to measure the distance and coverage of sidewalks along roadways.

  20. Gaitography applied to prosthetic walking.

    Science.gov (United States)

    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.

  1. Random Walks Estimate Land Value

    CERN Document Server

    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.

  2. Quantum Walks for Computer Scientists

    CERN Document Server

    Venegas-Andraca, Salvador

    2008-01-01

    Quantum computation, one of the latest joint ventures between physics and the theory of computation, is a scientific field whose main goals include the development of hardware and algorithms based on the quantum mechanical properties of those physical systems used to implement such algorithms. Solving difficult tasks (for example, the Satisfiability Problem and other NP-complete problems) requires the development of sophisticated algorithms, many of which employ stochastic processes as their mathematical basis. Discrete random walks are a popular choice among those stochastic processes. Inspir

  3. Step-Detection and Adaptive Step-Length Estimation for Pedestrian Dead-Reckoning at Various Walking Speeds Using a Smartphone.

    Science.gov (United States)

    Ho, Ngoc-Huynh; Truong, Phuc Huu; Jeong, Gu-Min

    2016-09-02

    We propose a walking distance estimation method based on an adaptive step-length estimator at various walking speeds using a smartphone. First, we apply a fast Fourier transform (FFT)-based smoother on the acceleration data collected by the smartphone to remove the interference signals. Then, we analyze these data using a set of step-detection rules in order to detect walking steps. Using an adaptive estimator, which is based on a model of average step speed, we accurately obtain the walking step length. To evaluate the accuracy of the proposed method, we examine the distance estimation for four different distances and three speed levels. The experimental results show that the proposed method significantly outperforms conventional estimation methods in terms of accuracy.

  4. Step-Detection and Adaptive Step-Length Estimation for Pedestrian Dead-Reckoning at Various Walking Speeds Using a Smartphone

    Directory of Open Access Journals (Sweden)

    Ngoc-Huynh Ho

    2016-09-01

    Full Text Available We propose a walking distance estimation method based on an adaptive step-length estimator at various walking speeds using a smartphone. First, we apply a fast Fourier transform (FFT-based smoother on the acceleration data collected by the smartphone to remove the interference signals. Then, we analyze these data using a set of step-detection rules in order to detect walking steps. Using an adaptive estimator, which is based on a model of average step speed, we accurately obtain the walking step length. To evaluate the accuracy of the proposed method, we examine the distance estimation for four different distances and three speed levels. The experimental results show that the proposed method significantly outperforms conventional estimation methods in terms of accuracy.

  5. Effect of Body Composition on Walking Economy

    Directory of Open Access Journals (Sweden)

    Maciejczyk Marcin

    2016-12-01

    Full Text Available Purpose. The aim of the study was to evaluate walking economy and physiological responses at two walking speeds in males with similar absolute body mass but different body composition. Methods. The study involved 22 young men with similar absolute body mass, BMI, aerobic performance, calf and thigh circumference. The participants differed in body composition: body fat (HBF group and lean body mass (HLBM group. In the graded test, maximal oxygen uptake (VO2max and maximal heart rate were measured. Walking economy was evaluated during two walks performed at two different speeds (4.8 and 6.0 km ‧ h-1. Results. The VO2max was similar in both groups, as were the physiological responses during slow walking. The absolute oxygen uptake or oxygen uptake relative to body mass did not significantly differentiate the studied groups. The only indicator significantly differentiating the two groups was oxygen uptake relative to LBM. Conclusions. Body composition does not significantly affect walking economy at low speed, while during brisk walking, the economy is better in the HLBM vs. HBF group, provided that walking economy is presented as oxygen uptake relative to LBM. For this reason, we recommend this manner of oxygen uptake normalization in the evaluation of walking economy.

  6. Motor modules in robot-aided walking

    Directory of Open Access Journals (Sweden)

    Gizzi Leonardo

    2012-10-01

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

  7. Excited random walks: results, methods, open problems

    CERN Document Server

    Kosygina, Elena

    2012-01-01

    We consider a class of self-interacting random walks in deterministic or random environments, known as excited random walks or cookie walks, on the d-dimensional integer lattice. The main purpose of this paper is two-fold: to give a survey of known results and some of the methods and to present several new results. The latter include functional limit theorems for transient one-dimensional excited random walks in bounded i.i.d. cookie environments as well as some zero-one laws. Several open problems are stated.

  8. Quantum walk with one variable absorbing boundary

    Science.gov (United States)

    Wang, Feiran; Zhang, Pei; Wang, Yunlong; Liu, Ruifeng; Gao, Hong; Li, Fuli

    2017-01-01

    Quantum walks constitute a promising ingredient in the research on quantum algorithms; consequently, exploring different types of quantum walks is of great significance for quantum information and quantum computation. In this study, we investigate the progress of quantum walks with a variable absorbing boundary and provide an analytical solution for the escape probability (the probability of a walker that is not absorbed by the boundary). We simulate the behavior of escape probability under different conditions, including the reflection coefficient, boundary location, and initial state. Moreover, it is also meaningful to extend our research to the situation of continuous-time and high-dimensional quantum walks.

  9. Walking in Place Through Virtual Worlds

    DEFF Research Database (Denmark)

    Nilsson, Niels Chr.; Serafin, Stefania; Nordahl, Rolf

    2016-01-01

    Immersive virtual reality (IVR) is seemingly on the verge of entering the homes of consumers. Enabling users to walk through virtual worlds in a limited physical space presents a challenge. With an outset in a taxonomy of virtual travel techniques, we argue that Walking-in-Place (WIP) techniques...... constitute a promising approach to virtual walking in relation to consumer IVR. Subsequently we review existing approaches to WIP locomotion and highlight the need for a more explicit focus on the perceived naturalness of WIP techniques; i.e., the degree to which WIP locomotion feels like real walking...

  10. Cochlea segmentation using iterated random walks with shape prior

    Science.gov (United States)

    Ruiz Pujadas, Esmeralda; Kjer, Hans Martin; Vera, Sergio; Ceresa, Mario; González Ballester, Miguel Ángel

    2016-03-01

    Cochlear implants can restore hearing to deaf or partially deaf patients. In order to plan the intervention, a model from high resolution µCT images is to be built from accurate cochlea segmentations and then, adapted to a patient-specific model. Thus, a precise segmentation is required to build such a model. We propose a new framework for segmentation of µCT cochlear images using random walks where a region term is combined with a distance shape prior weighted by a confidence map to adjust its influence according to the strength of the image contour. Then, the region term can take advantage of the high contrast between the background and foreground and the distance prior guides the segmentation to the exterior of the cochlea as well as to less contrasted regions inside the cochlea. Finally, a refinement is performed preserving the topology using a topological method and an error control map to prevent boundary leakage. We tested the proposed approach with 10 datasets and compared it with the latest techniques with random walks and priors. The experiments suggest that this method gives promising results for cochlea segmentation.

  11. On perturbations of almost distance-regular graphs

    CERN Document Server

    Dalfó, Cristina; Fiol, Miquel Angel; 10.1016/j.laa.2011.05.004

    2012-01-01

    In this paper we show that certain almost distance-regular graphs, the so-called $h$-punctually walk-regular graphs, can be characterized through the cospectrality of their perturbed graphs. A graph $G$ with diameter $D$ is called $h$-punctually walk-regular, for a given $h\\le D$, if the number of paths of length $\\ell$ between a pair of vertices $u,v$ at distance $h$ depends only on $\\ell$. The graph perturbations considered here are deleting a vertex, adding a loop, adding a pendant edge, adding/removing an edge, amalgamating vertices, and adding a bridging vertex. We show that for walk-regular graphs some of these operations are equivalent, in the sense that one perturbation produces cospectral graphs if and only if the others do. Our study is based on the theory of graph perturbations developed by Cvetkovi\\'c, Godsil, McKay, Rowlinson, Schwenk, and others. As a consequence, some new characterizations of distance-regular graphs are obtained.

  12. Assessing the feasibility of online SSVEP decoding in human walking using a consumer EEG headset.

    Science.gov (United States)

    Lin, Yuan-Pin; Wang, Yijun; Jung, Tzyy-Ping

    2014-08-09

    Bridging the gap between laboratory brain-computer interface (BCI) demonstrations and real-life applications has gained increasing attention nowadays in translational neuroscience. An urgent need is to explore the feasibility of using a low-cost, ease-of-use electroencephalogram (EEG) headset for monitoring individuals' EEG signals in their natural head/body positions and movements. This study aimed to assess the feasibility of using a consumer-level EEG headset to realize an online steady-state visual-evoked potential (SSVEP)-based BCI during human walking. This study adopted a 14-channel Emotiv EEG headset to implement a four-target online SSVEP decoding system, and included treadmill walking at the speeds of 0.45, 0.89, and 1.34 meters per second (m/s) to initiate the walking locomotion. Seventeen participants were instructed to perform the online BCI tasks while standing or walking on the treadmill. To maintain a constant viewing distance to the visual targets, participants held the hand-grip of the treadmill during the experiment. Along with online BCI performance, the concurrent SSVEP signals were recorded for offline assessment. Despite walking-related attenuation of SSVEPs, the online BCI obtained an information transfer rate (ITR) over 12 bits/min during slow walking (below 0.89 m/s). SSVEP-based BCI systems are deployable to users in treadmill walking that mimics natural walking rather than in highly-controlled laboratory settings. This study considerably promotes the use of a consumer-level EEG headset towards the real-life BCI applications.

  13. Use of the six-minute walk test to characterize golden retriever muscular dystrophy.

    Science.gov (United States)

    Acosta, Austin R; Van Wie, Emiko; Stoughton, William B; Bettis, Amanda K; Barnett, Heather H; LaBrie, Nicholas R; Balog-Alvarez, Cynthia J; Nghiem, Peter P; Cummings, Kevin J; Kornegay, Joe N

    2016-12-01

    Duchenne muscular dystrophy (DMD) is an X-linked recessive disorder in which loss of the dystrophin protein causes progressive skeletal/cardiac muscle degeneration and death within the third decade. For clinical trials and supportive animal studies, DMD disease progression and response to treatment must be established using outcome parameters (biomarkers). The 6-minute walk test (6MWT), defined as the distance an individual can walk in 6 minutes, is commonly used in DMD clinical trials and has been employed in dogs to characterize cardiac and respiratory disease severity. Building on methods established in DMD and canine clinical studies, we assessed the 6MWT in dogs with the DMD genetic homolog, golden retriever muscular dystrophy (GRMD). Twenty-one cross-bred golden retrievers were categorized as affected (DMD mutation and GRMD phenotype), carrier (female heterozygous for DMD mutation and no phenotype), and normal (wild type DMD gene and normal phenotype). When compared to grouped normal/carrier dogs, GRMD dogs walked shorter height-adjusted distances at 6 and 12 months of age and their distances walked declined with age. Percent change in creatine kinase after 6MWT was greater in GRMD versus normal/carrier dogs at 6 months, providing another potential biomarker. While these data generally support use of the 6MWT as a biomarker for preclinical GRMD treatment trials, there were certain limitations. Results of the 6MWT did not correlate with other outcome parameters for GRMD dogs when considered alone and an 80% increase in mean distance walked would be necessary to achieve satisfactory power. Copyright © 2016 Elsevier B.V. All rights reserved.

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

    Science.gov (United States)

    Yang, Shuozhi; Li, Qingguo

    2012-01-01

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

  15. Study of human walking patterns based on the parameter optimization of a passive dynamic walking robot.

    Science.gov (United States)

    Zang, Xizhe; Liu, Xinyu; Zhu, Yanhe; Zhao, Jie

    2016-04-29

    The study of human walking patterns mainly focuses on how control affects walking because control schemes are considered to be dominant in human walking. This study proposes that not only fine control schemes but also optimized body segment parameters are responsible for humans' low-energy walking. A passive dynamic walker provides the possibility of analyzing the effect of parameters on walking efficiency because of its ability to walk without any control. Thus, a passive dynamic walking model with a relatively human-like structure was built, and a parameter optimization process based on the gait sensitivity norm was implemented to determine the optimal mechanical parameters by numerical simulation. The results were close to human body parameters, thus indicating that humans can walk under a passive pattern based on their body segment parameters. A quasi-passive walking prototype was built on the basis of the optimization results. Experiments showed that a passive robot with optimized parameters could walk on level ground with only a simple hip actuation. This result implies that humans can walk under a passive pattern based on their body segment parameters with only simple control strategy implying that humans can opt to walk instinctively under a passive pattern.

  16. Interlimb coordination during forward walking is largely preserved in backward walking in children with cerebral palsy

    NARCIS (Netherlands)

    Meyns, P.; Molenaers, G.; Desloovere, K.; Duysens, J.E.J.

    2014-01-01

    OBJECTIVE: Limb kinematics in backward walking (BW) are essentially those of forward walking (FW) in reverse. It has been argued that subcortical mechanisms could underlie both walking modes. METHODS: Therefore, we tested whether participants with supraspinal/cortical deficits (i.e. cerebral palsy)

  17. Estimating distances from parallaxes

    CERN Document Server

    Bailer-Jones, C A L

    2015-01-01

    Astrometric surveys such as Gaia and LSST will measure parallaxes for hundreds of millions of stars. Yet they will not measure a single distance. Rather, a distance must be estimated from a parallax. In this didactic article, I show that doing this is not trivial once the fractional parallax error is larger than about 20%, which will be the case for about 80% of stars in the Gaia catalogue. Estimating distances is an inference problem in which the use of prior assumptions is unavoidable. I investigate the properties and performance of various priors and examine their implications. A supposed uninformative uniform prior in distance is shown to give very poor distance estimates (large bias and variance). Any prior with a sharp cut-off at some distance has similar problems. The choice of prior depends on the information one has available - and is willing to use - concerning, for example, the survey and the Galaxy. I demonstrate that a simple prior which decreases asymptotically to zero at infinite distance has g...

  18. Spatial search by quantum walk

    CERN Document Server

    Childs, A M; Childs, Andrew M.; Goldstone, Jeffrey

    2003-01-01

    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 sqrt(N) for d>2, and in time of order sqrt(N) poly(log N) 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 sqrt(N) speedup can also be achieved on the hypercube. We show that full sqrt(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 sqrt(N) poly(log N), and in d<4, the algorithm provides no speedup.

  19. Walking performance: correlation between energy cost of walking and walking participation. new statistical approach concerning outcome measurement.

    Directory of Open Access Journals (Sweden)

    Marco Franceschini

    Full Text Available 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.

  20. MOTIVATION FOR DISTANCE EDUCATION

    Directory of Open Access Journals (Sweden)

    R zvan TEF NESCU

    2009-10-01

    Full Text Available Beginning with the 1980’s the new information, communication and computer based technologies stimulated the development of the distance education. In Romania the universities adapted rapidly to this type of learning that became an important financing source for most of them. In this article we approach the causes of attraction for the distance education. For this purpose we use an investigation we did on a group of students at Distance Education including interviews regarding their reasons for choosing this type of learning.

  1. Treadmill walking is not equivalent to overground walking for the study of walking smoothness and rhythmicity in older adults.

    Science.gov (United States)

    Row Lazzarini, Brandi S; Kataras, Theodore J

    2016-05-01

    Treadmills are appealing for gait studies, but some gait mechanics are disrupted during treadmill walking. The purpose of this study was to examine the effects of speed and treadmill walking on walking smoothness and rhythmicity of 40 men and women between the ages of 70-96 years. Gait smoothness was examined during overground (OG) and treadmill (TM) walking by calculating the harmonic ratio from linear accelerations measured at the level of the lumbar spine. Rhythmicity was quantified as the stride time standard deviation. TM walking was performed at two speeds: a speed matching the natural OG walk speed (TM-OG), and a preferred TM speed (PTM). A dual-task OG condition (OG-DT) was evaluated to determine if TM walking posed a similar cognitive challenge. Statistical analysis included a one-way Analysis of Variance with Bonferroni corrected post hoc comparisons and the Wilcoxon signed rank test for non-normally distributed variables. Average PTM speed was slower than OG. Compared to OG, those who could reach the TM-OG speed (74.3% of sample) exhibited improved ML smoothness and rhythmicity, and the slower PTM caused worsened vertical and AP smoothness, but did not affect rhythmicity. PTM disrupted smoothness and rhythmicity differently than the OG-DT condition, likely due to reduced speed. The use of treadmills for gait smoothness and rhythmicity studies in older adults is problematic; some participants will not achieve OG speed during TM walking, walking at the TM-OG speed artificially improves rhythmicity and ML smoothness, and walking at the slower PTM speed worsens vertical and AP gait smoothness.

  2. Distance learning perspectives.

    Science.gov (United States)

    Pandza, Haris; Masic, Izet

    2013-01-01

    The development of modern technology and the Internet has enabled the explosive growth of distance learning. distance learning is a process that is increasingly present in the world. This is the field of education focused on educating students who are not physically present in the traditional classrooms or student's campus. described as a process where the source of information is separated from the students in space and time. If there are situations that require the physical presence of students, such as when a student is required to physically attend the exam, this is called a hybrid form of distance learning. This technology is increasingly used worldwide. The Internet has become the main communication channel for the development of distance learning.

  3. Learning Pullback HMM Distances.

    Science.gov (United States)

    Cuzzolin, Fabio; Sapienza, Michael

    2014-07-01

    Recent work in action recognition has exposed the limitations of methods which directly classify local features extracted from spatio-temporal video volumes. In opposition, encoding the actions' dynamics via generative dynamical models has a number of attractive features: however, using all-purpose distances for their classification does not necessarily deliver good results. We propose a general framework for learning distance functions for generative dynamical models, given a training set of labelled videos. The optimal distance function is selected among a family of pullback ones, induced by a parametrised automorphism of the space of models. We focus here on hidden Markov models and their model space, and design an appropriate automorphism there. Experimental results are presented which show how pullback learning greatly improves action recognition performances with respect to base distances.

  4. Walking on high heels changes muscle activity and the dynamics of human walking significantly

    DEFF Research Database (Denmark)

    Simonsen, Erik B; Svendsen, Morten Bo Søndergaard; Nørreslet, Andreas;

    2012-01-01

    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...

  5. Can the Cardiopulmonary 6-Minute Walk Test Reproduce the Usual Activities of Patients with Heart Failure?

    Directory of Open Access Journals (Sweden)

    Guimarães Guilherme Veiga

    2002-01-01

    Full Text Available OBJECTIVE: The 6-minute walk test is an way of assessing exercise capacity and predicting survival in heart failure. The 6-minute walk test was suggested to be similar to that of daily activities. We investigated the effect of motivation during the 6-minute walk test in heart failure. METHODS: We studied 12 males, age 45±12 years, ejection fraction 23±7%, and functional class III. Patients underwent the following tests: maximal cardiopulmonary exercise test on the treadmill (max, cardiopulmonary 6-minute walk test with the walking rhythm maintained between relatively easy and slightly tiring (levels 11 and 13 on the Borg scale (6EB, and cardiopulmonary 6-minute walk test using the usual recommendations (6RU. The 6EB and 6RU tests were performed on a treadmill with zero inclination and control of the velocity by the patient. RESULTS: The values obtained in the max, 6EB, and 6RU tests were, respectively, as follows: O2 consumption (ml.kg-1.min-1 15.4±1.8, 9.8±1.9 (60±10%, and 13.3±2.2 (90±10%; heart rate (bpm 142±12, 110±13 (77±9%, and 126±11 (89±7%; distance walked (m 733±147, 332±66, and 470±48; and respiratory exchange ratio (R 1.13±0.06, 0.9±0.06, and 1.06±0.12. Significant differences were observed in the values of the variables cited between the max and 6EB tests, the max and 6RU tests, and the 6EB and 6RU tests (p<0.05. CONCLUSION: Patients, who undergo the cardiopulmonary 6-minute walk test and are motivated to walk as much as they possibly can, usually walk almost to their maximum capacity, which may not correspond to that of their daily activities. The use of the Borg scale during the cardiopulmonary 6-minute walk test seems to better correspond to the metabolic demand of the usual activities in this group of patients.

  6. Realisation of an energy efficient walking robot

    NARCIS (Netherlands)

    Dertien, Edwin; Oort, van Gijs; Stramigioli, Stefano

    2006-01-01

    In this video the walking robot ‘Dribbel’ is presented, which has been built at the Control Engineering group of the University of Twente, the Netherlands. This robot has been designed with a focus on minimal energy consumption, using a passive dynamic approach. It is a so-called four-legged 2D walk

  7. Walking (Gait), Balance, and Coordination Problems

    Science.gov (United States)

    ... Seeking Services: Questions to Ask d Employment Disclosure Decisions Career Options Accommodations d Resources for Specific Populations Pediatric ... MS Navigator Program Patient Resources Contact Us d Careers in MS ... MS Symptoms Walking (Gait) Difficulties Share this page Facebook Twitter Email Walking (Gait) ...

  8. Quantum random walks and decision making.

    Science.gov (United States)

    Shankar, Karthik H

    2014-01-01

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

  9. Nordic walking improves mobility in Parkinson's disease.

    NARCIS (Netherlands)

    Eijkeren, FJ van; Reijmers, R.S.; Kleinveld, M.J.; Minten, A.; Bruggen, J.P.; Bloem, B.R.

    2008-01-01

    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 pr

  10. Nordic walking improves mobility in Parkinson's disease.

    NARCIS (Netherlands)

    Eijkeren, FJ van; Reijmers, R.S.; Kleinveld, M.J.; Minten, A.; Bruggen, J.P.; Bloem, B.R.

    2008-01-01

    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

  11. Locomotor sequence learning in visually guided walking.

    Science.gov (United States)

    Choi, Julia T; Jensen, Peter; Nielsen, Jens Bo

    2016-04-01

    Voluntary limb modifications must be integrated with basic walking patterns during visually guided walking. In this study we tested whether voluntary gait modifications can become more automatic with practice. We challenged walking control by presenting visual stepping targets that instructed subjects to modify step length from one trial to the next. Our sequence learning paradigm is derived from the serial reaction-time (SRT) task that has been used in upper limb studies. Both random and ordered sequences of step lengths were used to measure sequence-specific and sequence-nonspecific learning during walking. In addition, we determined how age (i.e., healthy young adults vs. children) and biomechanical factors (i.e., walking speed) affected the rate and magnitude of locomotor sequence learning. The results showed that healthy young adults (age 24 ± 5 yr,n= 20) could learn a specific sequence of step lengths over 300 training steps. Younger children (age 6-10 yr,n= 8) had lower baseline performance, but their magnitude and rate of sequence learning were the same compared with those of older children (11-16 yr,n= 10) and healthy adults. In addition, learning capacity may be more limited at faster walking speeds. To our knowledge, this is the first study to demonstrate that spatial sequence learning can be integrated with a highly automatic task such as walking. These findings suggest that adults and children use implicit knowledge about the sequence to plan and execute leg movement during visually guided walking.

  12. Flow Distances on Open Flow Networks

    CERN Document Server

    Guo, Liangzhu; Shi, Peiteng; Wang, Jun; Huang, Xiaohan; Zhang, Jiang

    2015-01-01

    Open flow network is a weighted directed graph with a source and a sink, depicting flux distributions on networks in the steady state of an open flow system. Energetic food webs, economic input-output networks, and international trade networks, are open flow network models of energy flows between species, money or value flows between industrial sectors, and goods flows between countries, respectively. Flow distances (first-passage or total) between any given two nodes $i$ and $j$ are defined as the average number of transition steps of a random walker along the network from $i$ to $j$ under some conditions. They apparently deviate from the conventional random walk distance on a closed directed graph because they consider the openness of the flow network. Flow distances are explicitly expressed by underlying Markov matrix of a flow system in this paper. With this novel theoretical conception, we can visualize open flow networks, calculating centrality of each node, and clustering nodes into groups. We apply fl...

  13. Design Issues for Hexapod Walking Robots

    Directory of Open Access Journals (Sweden)

    Franco Tedeschi

    2014-06-01

    Full Text Available Hexapod walking robots have attracted considerable attention for several decades. Many studies have been carried out in research centers, universities and industries. However, only in the recent past have efficient walking machines been conceived, designed and built with performances that can be suitable for practical applications. This paper gives an overview of the state of the art on hexapod walking robots by referring both to the early design solutions and the most recent achievements. Careful attention is given to the main design issues and constraints that influence the technical feasibility and operation performance. A design procedure is outlined in order to systematically design a hexapod walking robot. In particular, the proposed design procedure takes into account the main features, such as mechanical structure and leg configuration, actuating and driving systems, payload, motion conditions, and walking gait. A case study is described in order to show the effectiveness and feasibility of the proposed design procedure.

  14. Efficient quantum walk on a quantum processor

    Science.gov (United States)

    Qiang, Xiaogang; Loke, Thomas; Montanaro, Ashley; Aungskunsiri, Kanin; Zhou, Xiaoqi; O'Brien, Jeremy L.; Wang, Jingbo B.; Matthews, Jonathan C. F.

    2016-05-01

    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 framework for developing new quantum algorithms. Here 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 that could ultimately demonstrate quantum supremacy over classical computers. As a proof of principle, we experimentally implement the proposed quantum circuit on an example circulant graph using a two-qubit photonics quantum processor.

  15. Efficient quantum walk on a quantum processor.

    Science.gov (United States)

    Qiang, Xiaogang; Loke, Thomas; Montanaro, Ashley; Aungskunsiri, Kanin; Zhou, Xiaoqi; O'Brien, Jeremy L; Wang, Jingbo B; Matthews, Jonathan C F

    2016-05-05

    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 framework for developing new quantum algorithms. Here 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 that could ultimately demonstrate quantum supremacy over classical computers. As a proof of principle, we experimentally implement the proposed quantum circuit on an example circulant graph using a two-qubit photonics quantum processor.

  16. Getting mobile with a walking-help

    DEFF Research Database (Denmark)

    Krummheuer, Antonia Lina; Raudaskoski, Pirkko Liisa

    Ethnomethodology has been one of the few fields were mundane experiences and social ordering such as walking have been a focus of interest (e.g. Ryave and Schenkein 1974). In the present paper we want to discuss how this mundane practice sometimes needs to be achieved through the help of technology...... people with acquired brain injury were introduced to a new walking help that should enable them to walk (better). Our multimodal interaction analysis (Goodwin 2000) of the data will show how the practice of walking with this specific technology is dependent on the interplay of the material affordances...... of the technology (e.g. Gaver 1996), the bodily affordances (e.g. Sheller 2011) of the user and, furthermore, the scaffolding by an accompanying helper. The paper will discuss how movement as an enabled experience can be analysed as an entanglement of these three aspects. To do that, the situations of walk...

  17. Walk modularity and community structure in networks

    CERN Document Server

    Mehrle, David; Harkin, Anthony

    2014-01-01

    Modularity maximization has been one of the most widely used approaches in the last decade for discovering community structure in networks of practical interest in biology, computing, social science, statistical mechanics, and more. Modularity is a quality function that measures the difference between the number of edges found within clusters minus the number of edges one would statistically expect to find based on random chance. We present a natural generalization of modularity based on the difference between the actual and expected number of walks within clusters, which we call walk-modularity. Walk-modularity can be expressed in matrix form, and community detection can be performed by finding leading eigenvectors of the walk-modularity matrix. We demonstrate community detection on both synthetic and real-world networks and find that walk-modularity maximization returns significantly improved results compared to traditional modularity maximization.

  18. A Study of Real-time Peak Oxygen Consumption and Six-minute Walk Test

    Institute of Scientific and Technical Information of China (English)

    Guolin Zhang; Lan Guo; He Li; Jingzhuang Mai; Zhi Liu; Sixian Huang

    2007-01-01

    To assess the relationship between peak oxygen consumption( PVO2 ) and the ambulation distance in six-minute walk test (6MWT)among the healthy subjects.Methods The 51 healthy subjects were recruited for the six-minute walk test.Data of pulmonary gas exchange breath by breath,such as VO2,VCO2 were real-time measured with wireless remote sensing K4B2,so to study the relationship between peak oxygen uptake and the ambulation distance.Results It was noticed that there was a positive linear correlation between the ambulation distance and PVO2 ( r =0.619,P <0.001 ) in six-minute walk test.The regression equation was set up (VO2/kg =0.05D-6.331,P <0.001 ).PVO2 > PVCO2 ,R < 1 were found,which suggested that 6MWT was a test below anaerobic threshold.Conclusions There was a closely positive linear correlation between the ambulation distance and PVO2,which is safety,convenient and valuable for the evaluation of cardiopulmonary function and the treatment of cardiopulmonary rehabilitation.

  19. Perception of Egocentric Distance during Gravitational Changes in Parabolic Flight.

    Directory of Open Access Journals (Sweden)

    Gilles Clément

    Full Text Available We explored the effect of gravity on the perceived representation of the absolute distance of objects to the observers within the range from 1.5-6 m. Experiments were performed on board the CNES Airbus Zero-G during parabolic flights eliciting repeated exposures to short periods of microgravity (0 g, hypergravity (1.8 g, and normal gravity (1 g. Two methods for obtaining estimates of perceived egocentric distance were used: verbal reports and visually directed motion toward a memorized visual target. For the latter method, because normal walking is not possible in 0 g, blindfolded subjects translated toward the visual target by pulling on a rope with their arms. The results showed that distance estimates using both verbal reports and blind pulling were significantly different between normal gravity, microgravity, and hypergravity. Compared to the 1 g measurements, the estimates of perceived distance using blind pulling were shorter for all distances in 1.8 g, whereas in 0 g they were longer for distances up to 4 m and shorter for distances beyond. These findings suggest that gravity plays a role in both the sensorimotor system and the perceptual/cognitive system for estimating egocentric distance.

  20. Perception of Egocentric Distance during Gravitational Changes in Parabolic Flight.

    Science.gov (United States)

    Clément, Gilles; Loureiro, Nuno; Sousa, Duarte; Zandvliet, Andre

    2016-01-01

    We explored the effect of gravity on the perceived representation of the absolute distance of objects to the observers within the range from 1.5-6 m. Experiments were performed on board the CNES Airbus Zero-G during parabolic flights eliciting repeated exposures to short periods of microgravity (0 g), hypergravity (1.8 g), and normal gravity (1 g). Two methods for obtaining estimates of perceived egocentric distance were used: verbal reports and visually directed motion toward a memorized visual target. For the latter method, because normal walking is not possible in 0 g, blindfolded subjects translated toward the visual target by pulling on a rope with their arms. The results showed that distance estimates using both verbal reports and blind pulling were significantly different between normal gravity, microgravity, and hypergravity. Compared to the 1 g measurements, the estimates of perceived distance using blind pulling were shorter for all distances in 1.8 g, whereas in 0 g they were longer for distances up to 4 m and shorter for distances beyond. These findings suggest that gravity plays a role in both the sensorimotor system and the perceptual/cognitive system for estimating egocentric distance.

  1. Cross-Validation of a Recently Published Equation Predicting Energy Expenditure to Run or Walk a Mile in Normal-Weight and Overweight Adults

    Science.gov (United States)

    Morris, Cody E.; Owens, Scott G.; Waddell, Dwight E.; Bass, Martha A.; Bentley, John P.; Loftin, Mark

    2014-01-01

    An equation published by Loftin, Waddell, Robinson, and Owens (2010) was cross-validated using ten normal-weight walkers, ten overweight walkers, and ten distance runners. Energy expenditure was measured at preferred walking (normal-weight walker and overweight walkers) or running pace (distance runners) for 5 min and corrected to a mile. Energy…

  2. Heading assessment by "tunnel vision" patients and control subjects standing or walking in a virtual reality environment.

    Science.gov (United States)

    Apfelbaum, Henry; Pelah, Adar; Peli, Eli

    2007-01-01

    Virtual reality locomotion simulators are a promising tool for evaluating the effectiveness of vision aids to mobility for people with low vision. This study examined two factors to gain insight into the verisimilitude requirements of the test environment: the effects of treadmill walking and the suitability of using controls as surrogate patients. Ten "tunnel vision" patients with retinitis pigmentosa (RP) were tasked with identifying which side of a clearly visible obstacle their heading through the virtual environment would lead them, and were scored both on accuracy and on their distance from the obstacle when they responded. They were tested both while walking on a treadmill and while standing, as they viewed a scene representing progress through a shopping mall. Control subjects, each wearing a head-mounted field restriction to simulate the vision of a paired patient, were also tested. At wide angles of approach, controls and patients performed with a comparably high degree of accuracy, and made their choices at comparable distances from the obstacle. At narrow angles of approach, patients' accuracy increased when walking, while controls' accuracy decreased. When walking, both patients and controls delayed their decisions until closer to the obstacle. We conclude that a head-mounted field restriction is not sufficient for simulating tunnel vision, but that the improved performance observed for walking compared to standing suggests that a walking interface (such as a treadmill) may be essential for eliciting natural perceptually-guided behavior in virtual reality locomotion simulators.

  3. The Bobath Concept in Walking Activity in Chronic Stroke Measured Through the International Classification of Functioning, Disability and Health.

    Science.gov (United States)

    Benito García, Miguel; Atín Arratibel, María Ángeles; Terradillos Azpiroz, Maria Estíbaliz

    2015-12-01

    The aim of this study is to evaluate the effectiveness of a rehabilitation programme based on the Bobath concept in order to improve walking activity in patients with chronic stroke and to show the usefulness of the International Classification of Functioning, Disability and Health (ICF) as a tool for gathering functioning information. This study is a repeated measures study. The setting of this study is an outpatient neurological rehabilitation centre based on a multidisciplinary approach. Twenty-four participants suffering from chronic stroke (>1 year and a half and Bobath concept principles with three weekly individual physiotherapy sessions of 45 min each over a 6-month period was the intervention for this study. The measures used were Modified Emory Functional Ambulation Profile, 10-m walk test, 6-min walk test, muscle strength testing and subsequent codification of these results into ICF qualifiers. The results of the study showed significant improvement in activities of walking long distances, on different surfaces and around obstacles. There was no significant improvement in the activity of walking short distances or for muscle power functions. A rehabilitation programme based on the Bobath Concept improved walking activities in people with chronic stroke. For this intervention, the use of the ICF qualifiers was sensitive in perceiving post-treatment changes. Copyright © 2014 John Wiley & Sons, Ltd.

  4. Effect of walking stress on growth, physiological adaptability and endocrine responses in Malpura ewes in a semi-arid tropical environment

    Science.gov (United States)

    Sejian, Veerasamy; Maurya, Vijai P.; Naqvi, Syed M. K.

    2012-03-01

    Sheep in hot semi-arid environments are mostly reared using extensive systems. In addition to thermal stress and feed scarcity, the animals need to walk long distances for grazing in this ecological zone. A study was conducted to assess the effect of long-distance walking on adaptive capability in terms of physiological, biochemical and endocrine responses in Malpura ewes. Fourteen adult Malpura non-pregnant ewes weighing between 33 and 35 kg were used in the study. The ewes were randomly allocated into two groups of seven animals each: GI ( n = 7; Control), and GII ( n = 7; walking stress). The animals were stall-fed with a diet consisting of 70% roughage and 30% concentrate. Both GI and GII ewes had uniform access to feed and water. The walking stress group (GII) ewes were made to walk 14 km in two spans between 0900 and 1500 hours with 1 h 30 min for each span (7 km) of walking. The ewes subjected to walking stress (GII) were prevented from grazing by applying a face mask made of cotton thread. The study was conducted for a period of two estrous cycles (35 days) during the autumn season (October-November). Physiological responses were recorded twice daily at 0800 and 1400 hours at weekly intervals. Blood samples were collected from the jugular vein at weekly intervals to study the effects of walking stress on blood biochemical and endocrine parameters. The results indicate that walking stress had significant ( P stress did not influence the reproductive hormone levels. The significant changes in RR, RT, plasma cortisol, T3 and T4 show that Malpura ewes have the capability to adapt to long-distance walking, and that adrenal and thyroid gland hormones play a significant role in such adaptation.

  5. Effect of walking stress on growth, physiological adaptability and endocrine responses in Malpura ewes in a semi-arid tropical environment.

    Science.gov (United States)

    Sejian, Veerasamy; Maurya, Vijai P; Naqvi, Syed M K

    2012-03-01

    Sheep in hot semi-arid environments are mostly reared using extensive systems. In addition to thermal stress and feed scarcity, the animals need to walk long distances for grazing in this ecological zone. A study was conducted to assess the effect of long-distance walking on adaptive capability in terms of physiological, biochemical and endocrine responses in Malpura ewes. Fourteen adult Malpura non-pregnant ewes weighing between 33 and 35 kg were used in the study. The ewes were randomly allocated into two groups of seven animals each: GI (n = 7; Control), and GII (n = 7; walking stress). The animals were stall-fed with a diet consisting of 70% roughage and 30% concentrate. Both GI and GII ewes had uniform access to feed and water. The walking stress group (GII) ewes were made to walk 14 km in two spans between 0900 and 1500 hours with 1 h 30 min for each span (7 km) of walking. The ewes subjected to walking stress (GII) were prevented from grazing by applying a face mask made of cotton thread. The study was conducted for a period of two estrous cycles (35 days) during the autumn season (October-November). Physiological responses were recorded twice daily at 0800 and 1400 hours at weekly intervals. Blood samples were collected from the jugular vein at weekly intervals to study the effects of walking stress on blood biochemical and endocrine parameters. The results indicate that walking stress had significant (P stress did not influence the reproductive hormone levels. The significant changes in RR, RT, plasma cortisol, T(3) and T(4) show that Malpura ewes have the capability to adapt to long-distance walking, and that adrenal and thyroid gland hormones play a significant role in such adaptation.

  6. Analysis and Development of Walking Algorithm Kinematic Model for 5-Degree of Freedom Bipedal Robot

    Directory of Open Access Journals (Sweden)

    Gerald Wahyudi Setiono

    2012-12-01

    Full Text Available A design of walking diagram and the calculation of a bipedal robot have been developed. The bipedal robot was designed and constructed with several kinds of servo bracket for the legs, two feet and a hip. Each of the bipedal robot leg was 5-degrees of freedom, three pitches (hip joint, knee joint and ankle joint and two rolls (hip joint and ankle joint. The walking algorithm of this bipedal robot was based on the triangle formulation of cosine law to get the angle value at each joint. The hip height, height of the swinging leg and the step distance are derived based on linear equation. This paper discussed the kinematic model analysis and the development of the walking diagram of the bipedal robot. Kinematics equations were derived, the joint angles were simulated and coded into Arduino board to be executed to the robot.

  7. Snell's law and walking droplets

    Science.gov (United States)

    Bush, John; Pucci, Giuseppe; Aubin, Benjamin; Brun, Pierre-Thomas; Faria, Luiz

    2016-11-01

    Droplets walking on the surface of a vibrating bath have been shown to exhibit a number of quantum-like features. We here present the results of a combined experimental and theoretical investigation of such droplets crossing a linear step corresponding to a reduction in bath depth. When the step is sufficiently large, the walker reflects off the step; otherwise, it is refracted as it crosses the step. Particular attention is given to an examination of the regime in which the droplet obeys a form of Snell's Law, a behavior captured in accompanying simulations. Attempts to provide theoretical rationale for the dependence of the effective refractive index on the system parameters are described. Supported by NSF through CMMI-1333242.

  8. Quantum walks and gravitational waves

    Science.gov (United States)

    Arnault, Pablo; Debbasch, Fabrice

    2017-08-01

    A new family of discrete-time quantum walks (DTQWs) propagating on a regular (1 + 2)D spacetime lattice is introduced. The continuum limit of these DTQWs is shown to coincide with the dynamics of a Dirac fermion coupled to an arbitrary relativistic gravitational field. This family is used to model the influence of arbitrary linear gravitational waves (GWs) on DTQWs. Pure shear GWs are studied in detail. We show that on large spatial scales, the spatial deformation generated by the wave induces a rescaling of the eigen-energies by a certain anisotropic factor which can be computed exactly. The effect of pure shear GWs on fermion interference patterns is also investigated, both on large scales and on scales comparable to the lattice spacing.

  9. Random walks on reductive groups

    CERN Document Server

    Benoist, Yves

    2016-01-01

    The classical theory of Random Walks describes the asymptotic behavior of sums of independent identically distributed random real variables. This book explains the generalization of this theory to products of independent identically distributed random matrices with real coefficients. Under the assumption that the action of the matrices is semisimple – or, equivalently, that the Zariski closure of the group generated by these matrices is reductive - and under suitable moment assumptions, it is shown that the norm of the products of such random matrices satisfies a number of classical probabilistic laws. This book includes necessary background on the theory of reductive algebraic groups, probability theory and operator theory, thereby providing a modern introduction to the topic.

  10. Recurrence in coined quantum walks

    Energy Technology Data Exchange (ETDEWEB)

    Kiss, T; Kecskes, L [Research Institute for Solid State Physics and Optics, Hungarian Academy of Sciences, Konkoly-Thege M. u. 29-33, H-1121 Budapest (Hungary); Stefanak, M; Jex, I [Department of Physics, FJFI CVUT v Praze, Brehova 7, 115 19 Praha 1-Stare Mesto (Czech Republic)], E-mail: tkiss@szfki.hu

    2009-07-15

    Recurrence of quantum walks on lattices can be characterized by the generalized Polya number. Its value reflects the difference between a classical and a quantum system. The dimension of the lattice is not a unique parameter in the quantum case; both the coin operator and the initial quantum state of the coin influence the recurrence in a nontrivial way. In addition, the definition of the Polya number involves measurement of the system. Depending on how measurement is included in the definition, the recurrence properties vary. We show that in the limiting case of frequent, strong measurements, one can approach the classical dynamics. Comparing various cases, we have found numerical indication that our previous definition of the Polya number provides an upper limit.

  11. Symbolic walk in regular networks

    Science.gov (United States)

    Ermann, Leonardo; Carlo, Gabriel G.

    2015-01-01

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

  12. Presence at a distance.

    Science.gov (United States)

    Haddouk, Lise

    2015-01-01

    Nowadays in the context of the cyberculture, computer-mediated inter-subjective relationships are part of our everyday lives, in both the professional and personal spheres, and for all age groups. In the clinical field, many applications have been developed to facilitate the exchange of informations and mediate the relationship between patient and therapist. In psychology, more or less immersive technologies are used, to encourage the feeling of presence among the users, and to trigger certain psychological processes. In our research, we have explored the remote clinical interview through videoconferencing, with the development and utilisation of the iPSY platform, totally focused on this objective. In this context, we have considered the notion of intersubjectivity, despite the physical absence. This research is leading us today to envision the notions of distance and presence, and possibly to redefine them. Thus, can we still oppose physical distance to psychological distance? Can we still affirm that the physical absence does not permit a psychological co-presence in certain interactions, like this observed in video interviews? The results show that the psychological processes, activated in this context, are similar to those observed in "traditional" clinical consults between the patient and the therapist. However, certain specifics have led us to consider the concept of distance, here influenced by the framework, and to observe its effects. This distance could possibly constitute a therapeutic lever for some patients, notably for those who have difficulties establishing the right psychological distance in their relationships with others. According to these results, can "distance" still be opposed to "presence", or could it be re-defined? This also opens up questions on the more general concept of digital relationships, and the definition of their specificities.

  13. Blindman-Walking Optimization Method

    Directory of Open Access Journals (Sweden)

    Chunming Li

    2010-12-01

    Full Text Available Optimization methods are all implemented with the hypothesis of unknowing the mathematic express of objective objection. Using the human analogy innovative method, the one-dimension blind-walking optimal method is proposed in this paper. The theory and the algorithm of this method includes halving, doubling, reversing probing step and verifying the applicability condition. Double-step is available to make current point moving to the extremum point. Half-step is available to accelerate convergence. In order to improve the optimization, the applicability condition decides whether update current point or not. The operation process, algorithmic flow chart and characteristic analysis of the method were given. Two optimization problems with unimodal or multimodal objective function were solved by the proposed method respectively. The simulation result shows that the proposed method is better than the ordinary method. The proposed method has the merit of rapid convergence, little calculation capacity, wide applicable range, etc. Taking the method as innovative kernel, the random research method, feasible direction method and complex shape method were improved. Taking the innovative content of this paper as innovative kernel, a monograph was published. The other innovations of the monograph are listed, such as applied algorithm of Karush-Kuhn-Tucker (KKT qualifications on judging the restriction extremum point, the design step of computing software, the complementarity and derivation of Powell criterion, the method of keeping the complex shape not to deduce dimension and the analysis of gradual optimization characteristic, the reinforced wall of inner point punish function method, the analysis of problem with constrained monstrosity extremum point, the improvement of Newton method and the validation of optimization idea of blind walking repeatedly, the explanation of later-day optimization method, the conformity of seeking algorithm needing the

  14. Evaluating patients' walking capacity during hospitalization for lung cancer resection†.

    Science.gov (United States)

    Esteban, Pedro A; Hernández, Nieves; Novoa, Nuria M; Varela, Gonzalo

    2017-05-04

    The goal of this study was to describe non-supervised daily physical activity in patients during the period immediately following anatomical lung resection. The study was an observational study on 50 consecutive patients (33 men) admitted for anatomical lung resection over a 4-month period. All cases were approached using a minimally invasive technique. Patients were instructed by nursing and physiotherapy staff and asked to wear a portable pedometer (Omron HJ-720 T-E2) from admission until hospital discharge, excluding the day of the operation and the first hours in the recovery room. The variables collected included sex, age, body mass index, type of lung resection, cardiopulmonary postoperative complications, percentage forced expiratory volume in 1 s, percentage single-breath carbon monoxide diffusing capacity, predicted postoperative forced expiratory volume in 1 s calculated according to functional segments removed at surgery, predicted postoperative single-breath carbon monoxide diffusing capacity calculated according to functional segments removed at surgery, total steps, aerobic steps and daily total strolled distance in metres. Comparison of activity was analysed using the paired t -test for individual data evolution and the unpaired t -test for patients showing complications or not. Body mass index and exercise capacity were analysed using the Spearman correlation analysis. A total of 34 patients underwent lobectomy or bilobectomy. All patients could walk on the first postoperative day. The average walked distance on the first and fourth postoperative days was 6100 m and 7400 m, respectively. Compared with the preoperative day, patients walked significantly fewer total steps on Day 1 and Day 2 (Day 1, P  = 0.0001; Day 2, P  = 0.049). The rate of aerobic to total daily steps was comparable after the second postoperative day. Patients having any postoperative cardiopulmonary complication showed a significantly inferior walking capacity ( P

  15. Going for distance and going for speed: effort and optical variables shape information for distance perception from observation to response.

    Science.gov (United States)

    Hajnal, Alen; Bunch, David A; Kelty-Stephen, Damian G

    2014-05-01

    Visually guided distance perception reflects a relationship of geometrical optical variables with the effort required when traversing the distance. We probed how the representations encoding optical variables might define this relationship. Participants visually judged distances on sloped surfaces and reproduced these distances over flat terrain by walking while blindfolded. We examined the responses for the effects of optical variables (i.e., angular declinations from eye height) and tested whether four measures of trial-by-trial effort moderated the use of the represented optical variables. We predicted that observation time and response speed relative to the observed distance would accentuate the effects of encoded optical variables, and that response time and response speed relative to the traversed distance would reduce the effects of those variables. The results confirmed all of the effects except those of observation time. Given the benefits of longer study for strengthening a memory trace, the failure of observation time to predict the use of optical variables raises questions about the representational encoding of visual traces for distance perception. Relationships among optical variables and other effort measures implicate the interaction of processes across multiple time scales, as in cascade dynamics. Cascade dynamics may provide new directions for accounts of visually guided distance perception.

  16. Random Walk Routing in WSNs with Regular Topologies

    Institute of Scientific and Technical Information of China (English)

    Hui Tian; Hong Shen; Teruo Matsuzawa

    2006-01-01

    Topology is one of the most important characteristics for any type of networks because it represents the network's inherent properties and has great impact on the performance of the network. For wireless sensor networks (WSN),a well-deployed regular topology can help save more energy than what a random topology can do. WSNs with regular topologies can prolong network lifetime as studied in many previous work. However, little work has been done in developing effective routing algorithms for WSNs with regular topologies, except routing along a shortest path with the knowledge of global location information of sensor nodes. In this paper, a new routing protocol based on random walk is proposed. It does not require global location information. It also achieves load balancing property inherently for WSNs which is difficult to achieve by other routing protocols. In the scenarios where the message required to be sent to the base station is in comparatively small size with the inquiry message among neighboring nodes, it is proved that the random walk routing protocol can guarantee high probability of successful transmission from the source to the base station with the same amount of energy consumption as the shortest path routing. Since in many applications of WSNs, sensor nodes often send only beep-like small messages to the base station to report their status, our proposed random walk routing is thus a viable scheme and can work very efficiently especially in these application scenarios. The random walk routing provides load balancing in the WSN as mentioned, however, the nodes near to the base station are inevitably under heavier burden than those far away from the base station. Therefore, a density-aware deployment scheme is further proposed to guarantee that the heavy-load nodes do not affect the network lifetime even if their energy is exhausted. The main idea is deploying sensors with different densities according to their distance to the base station. It will be

  17. Assessment of exercise capacity in African patients with chronic heart failure using six minutes walk test

    Directory of Open Access Journals (Sweden)

    Rufus A Adedoyin

    2010-02-01

    Full Text Available Rufus A Adedoyin1, Samuel A Adeyanju2, Michael O Balogun3, Anthony O Akintomide3, Rasaaq A Adebayo3, Patience O Akinwusi4, Taofeek O Awotidebe11Department of Medical Rehabilitation, Obafemi Awolowo University, Ile-Ife, Nigeria; 2Department of Physical and Health Education, Obafemi Awolowo University, Ile-Ife, Nigeria; 3Department of Medicine, Obafemi Awolowo University, Ile-Ife, Nigeria; 4Department of Medicine, Ladoke Akintola University of Technology, Osogbo, NigeriaBackground: The purpose of this study was to assess the functional capacity during a 6-minute corridor walk and a 6-minute bicycle ergometry exercise in patients with chronic heart failure (CHF.Method: Thirty five patients with stable CHF were recruited for the study. Each subject performed six minutes corridor walk and 6-minute bicycle ergometry testing. The 6-minute walk required the subjects to walk at a self selected speed on a 20 meter marked level ground for 6-minute. All the subjects also performed a 6-minute exercise on a stationary bicycle ergometer with initial resistance of 20 watts and increased by 10 watts after 3-minutes. The perceived rate of exertion was assessed using a modified Borg Scale after each exercise mode. The maximum oxygen consumption was derived using American College of Sport Medicine equations.Results: Result showed high positive correlation between distance walked in the 6-minute and the maximum volume of oxygen (VO2 max (r = 0.65, P < 0.01. The average distance walked was 327 m ± 12.03 m. The VO2 max estimated during bicycle ergometry was higher (13.7 ± 1.9 L than during the six minutes walk (8.9 ± 1.2 L.Conclusion: Six minutes walk could be useful to evaluate exercise tolerance in patients with chronic heart failure, while the bicycle ergometer could be more appropriate in the assessment of maximum functional capacity in these patients.Keywords: 6-minute walk, CHF, bicycle ergometer

  18. Distance learning for similarity estimation

    NARCIS (Netherlands)

    Yu, J.; Amores, J.; Sebe, N.; Radeva, P.; Tian, Q.

    2008-01-01

    In this paper, we present a general guideline to find a better distance measure for similarity estimation based on statistical analysis of distribution models and distance functions. A new set of distance measures are derived from the harmonic distance, the geometric distance, and their generalized

  19. Aggregation and spatial analysis of walking activity in an urban area: results from the Halifax space-time activity survey

    Science.gov (United States)

    Neatt, K.; Millward, H.; Spinney, J.

    2016-04-01

    This study examines neighborhood characteristics affecting the incidence of walking trips in urban and suburban areas of Halifax, Canada. We employ data from the Space-Time Activity Research (STAR) survey, conducted in 2007-8. Primary respondents completed a two- day time-diary survey, and their movements were tracked using a GPS data logger. Primary respondents logged a total of 5,005 walking trips, specified by 781,205 individual GPS points. Redundant and erroneous points, such as those with zero or excessive speed, were removed. Data points were then imported into ArcGIS, converted from points to linear features, visually inspected for data quality, and cleaned appropriately. From mapped walking tracks we developed hypotheses regarding variations in walking density. To test these, walking distances were aggregated by census tracts (CTs), and expressed as walking densities (per resident, per metre of road, and per developed area). We employed multivariate regression to examine which neighborhood (CT) variables are most useful as estimators of walking densities. Contrary to much of the planning literature, built-environment measures of road connectivity and dwelling density were found to have little estimating power. Office and institutional land uses are more useful estimators, as are the income and age characteristics of the resident population.

  20. Hematological and hemorheological determinants of the six-minute walk test performance in children with sickle cell anemia.

    Directory of Open Access Journals (Sweden)

    Xavier Waltz

    Full Text Available The six-minute walk test is a well-established submaximal exercise reflecting the functional status and the clinical severity of sickle cell patients. The aim of the present cross-sectional study was to investigate the biological determinants of the six-minute walk test performance in children with sickle cell anemia. Hematological and hemorheological parameters, pulmonary function and the six-minute walk test performance were determined in 42 children with sickle cell anemia at steady state. The performance during the six-minute walk test was normalized for age, sex and height and expressed as percentage of the predicted six-minute walk distance. We showed that a high level of anemia, a low fetal hemoglobin expression and low red blood cell deformability were independent predictors of a low six-minute walk test performance. This study describes for the first time the impact of blood rheology in the six-minute walk test performance in children with sickle cell anemia.

  1. New walking and cycling infrastructure and modal shift in the UK: A quasi-experimental panel study.

    Science.gov (United States)

    Song, Yena; Preston, John; Ogilvie, David

    2017-01-01

    Heavy dependency on car use leads to traffic congestion, pollution, and physical inactivity, which impose high direct and indirect costs on society. Promoting walking and cycling has been recognised as one of the means of mitigating such negative effects. Various approaches have been taken to enhance walking and cycling levels and to reduce the use of automobiles. This paper examines the effectiveness of infrastructure interventions in promoting walking and cycling for transport. Two related sets of panel data, covering elapsed time periods of one and two years, were analysed to track changes in travel behaviour following provision of new walking and cycling infrastructure so that modal shift from private car use to walking and cycling can be investigated. Two types of exposure measures were tested: distance from the infrastructure (a measure of potential usage), and actual usage of the infrastructure. Only the latter measure was statistically significantly associated with modal shift. This in turn suggested that infrastructure provision was not a sufficient condition for modal shift, but may have been a necessary condition. Along with the use of new infrastructure, the loss of employment, higher education, being male and being part of the ethnic majority were consistently found to be significantly and positively associated with modal shift towards walking and cycling. The findings of this study support the construction of walking and cycling routes, but also suggest that such infrastructure alone may not be enough to promote active travel.

  2. Effects of Lower Limb Length and Body Proportions on the Energy Cost of Overground Walking in Older Persons

    Directory of Open Access Journals (Sweden)

    Federica Vannetti

    2014-01-01

    Full Text Available Background. Although walking has been extensively investigated in its biomechanical and physiological aspects, little is known on whether lower limb length and body proportions affect the energy cost of overground walking in older persons. Methods. We enrolled 50 men and 12 women aged 65 years and over, mean 69.1 ± SD 5.4, who at the end of their cardiac rehabilitation program performed the six-minute walk test while wearing a portable device for direct calorimetry and who walked a distance comparable to that of nondisabled community-dwelling older persons. Results. In the multivariable regression model (F = 12.75, P<0.001, adjusted R2=0.278 the energy cost of overground walking, expressed as the net energy expenditure, in kg−1 sec−1, needed to provide own body mass with 1 joule kinetic energy, was inversely related to lower limb length and directly related to lower limb length to height ratio (β±SEβ = -3.72*10-3±0.74*10-3, P<0.001, and 6.61*10-3±2.14*10-3, P=0.003, resp.. Ancillary analyses also showed that, altogether, 1 cm increase in lower limb length reduced the energy cost of overground walking by 2.57% (95%CI 2.35–2.79. Conclusions. Lower limb length and body proportions actually affect the energy cost of overground walking in older persons.

  3. Stereoscopic distance perception

    Science.gov (United States)

    Foley, John M.

    1989-01-01

    Limited cue, open-loop tasks in which a human observer indicates distances or relations among distances are discussed. By open-loop tasks, it is meant tasks in which the observer gets no feedback as to the accuracy of the responses. What happens when cues are added and when the loop is closed are considered. The implications of this research for the effectiveness of visual displays is discussed. Errors in visual distance tasks do not necessarily mean that the percept is in error. The error could arise in transformations that intervene between the percept and the response. It is argued that the percept is in error. It is also argued that there exist post-perceptual transformations that may contribute to the error or be modified by feedback to correct for the error.

  4. Walking dreams in congenital and acquired paraplegia.

    Science.gov (United States)

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

    2011-12-01

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

  5. The Walking Renaissance: A Longitudinal Analysis of Walking Travel in the Greater Los Angeles Area, USA

    Directory of Open Access Journals (Sweden)

    Kenneth Joh

    2015-07-01

    Full Text Available 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 such as walking, bicycling and transit in auto-oriented cities such as Los Angeles. Although many past studies have analyzed changes in walking travel across the U.S., there is little clarity on the drivers of change. We address this gap by conducting a longitudinal analysis of walking travel in the greater Los Angeles area from 2001 to 2009. We use travel diary and household data from regional and national surveys to analyze changes in walking trip shares and rates across our study area. Results show that walking has significantly increased across most of Los Angeles, and that increases in walking trips generally correspond with increases in population, employment, and transit service densities. Estimates from fixed-effects regression analysis generally suggest a positive association between population density and walking, and that higher increases in transit stop density are correlated with increased walking trips to and from transit stops. These findings illustrate how regional planning efforts to pursue a coordinated land use-transit planning strategy can help promote walking in auto-oriented or vehicle adopting cities.

  6. Community walking training program improves walking function and social participation in chronic stroke patients.

    Science.gov (United States)

    Kim, MinKyu; Cho, KiHun; Lee, WanHee

    2014-01-01

    Stroke patients live with balance and walking dysfunction. Walking is the most important factor for independent community activities. The purpose of this study was to investigate the effect of a community walking training program (CWTP) within the real environment on walking function and social participation in chronic stroke patients. Twenty-two stroke patients (13 male, 50.45 years old, post stroke duration 231.64 days) were randomly assigned to either the CWTP group or the control group. All subjects participated in the same standard rehabilitation program consisting of physical and occupational therapy for 60 min per day, five times a week, for four weeks. In addition, the CWTP group participated in CWTP for 30 min per day, five times a week, for four weeks. Walking function was assessed using the 10-m walk test (measurement for 10-meter walking speed), 6-min walk assessment (measurement of gait length for 6-minutes), and community gait assessment. Social participation was assessed using a social participation domain of stroke impact scale. In walking function, greater improvement was observed in the CWTP group compared with the control group (P participation improved more in the CWTP group compared with the control group (P participation in chronic stroke patients. Therefore, we suggest that CWTP within the real environment may be an effective method for improving walking function and social participation of chronic stroke patients when added to standard rehabilitation.

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

    Directory of Open Access Journals (Sweden)

    I. Reuter

    2011-01-01

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

  8. Walking economy during cued versus non-cued treadmill walking in persons with Parkinson's disease.

    Science.gov (United States)

    Gallo, Paul M; McIsaac, Tara L; Garber, Carol Ewing

    2013-01-01

    Gait impairment is common in Parkinson's disease (PD) and may result in greater energy expenditure, poorer walking economy, and fatigue during activities of daily living. Auditory cueing is an effective technique to improve gait; but the effects on energy expenditure are unknown. To determine whether energy expenditure differs in individuals with PD compared with healthy controls and if auditory cueing improves walking economy in PD. Twenty participants (10 PD and 10 controls) came to the laboratory for three sessions. Participants performed two, 6-minute bouts of treadmill walking at two speeds (1.12 m·sec-1 and 0.67 m·sec-1). One session used cueing and the other without cueing. A metabolic cart measured energy expenditure and walking economy was calculated (energy expenditure/power). PD had worse walking economy and higher energy expenditure than control participants during cued and non-cued walking at the 0.67 m·sec-1 speed and during non-cued walking at the 1.12 m·sec-1. With auditory cueing, energy expenditure and walking economy worsened in both participant groups. People with PD use more energy and have worse walking economy than adults without PD. Walking economy declines further with auditory cuing in persons with PD.

  9. Noise in two-color electronic distance meter measurements revisited

    Science.gov (United States)

    Langbein, J.

    2004-01-01

    Frequent, high-precision geodetic data have temporally correlated errors. Temporal correlations directly affect both the estimate of rate and its standard error; the rate of deformation is a key product from geodetic measurements made in tectonically active areas. Various models of temporally correlated errors are developed and these provide relations between the power spectral density and the data covariance matrix. These relations are applied to two-color electronic distance meter (EDM) measurements made frequently in California over the past 15-20 years. Previous analysis indicated that these data have significant random walk error. Analysis using the noise models developed here indicates that the random walk model is valid for about 30% of the data. A second 30% of the data can be better modeled with power law noise with a spectral index between 1 and 2, while another 30% of the data can be modeled with a combination of band-pass-filtered plus random walk noise. The remaining 10% of the data can be best modeled as a combination of band-pass-filtered plus power law noise. This band-pass-filtered noise is a product of an annual cycle that leaks into adjacent frequency bands. For time spans of more than 1 year these more complex noise models indicate that the precision in rate estimates is better than that inferred by just the simpler, random walk model of noise.

  10. Is Walking Capacity in Subjects with Multiple Sclerosis Primarily Related to Muscle Oxidative Capacity or Maximal Muscle Strength? A Pilot Study

    Directory of Open Access Journals (Sweden)

    Dominique Hansen

    2014-01-01

    Full Text Available Background and Purpose. Walking capacity is reduced in subjects with multiple sclerosis (MS. To develop effective exercise interventions to enhance walking capacity, it is important to determine the impact of factors, modifiable by exercise intervention (maximal muscle strength versus muscle oxidative capacity, on walking capacity. The purpose of this pilot study is to discriminate between the impact of maximal muscle strength versus muscle oxidative capacity on walking capacity in subjects with MS. Methods. From 24 patients with MS, muscle oxidative capacity was determined by calculation of exercise-onset oxygen uptake kinetics (mean response time during submaximal exercise bouts. Maximal muscle strength (isometric knee extension and flexion peak torque was assessed on dynamometer. All subjects completed a 6-minute walking test. Relationships between walking capacity (as a percentage of normal value and muscle strength (of knee flexors and extensors versus muscle oxidative capacity were assessed in multivariate regression analyses. Results. The expanded disability status score (EDSS showed a significant univariate correlation (r=-0.70, P<0.004 with walking capacity. In multivariate regression analyses, EDSS and mean response time, but not muscle strength, were independently related to walking capacity (P<0.05. Conclusions. Walking distance is, next to disability level and not taking neurologic symptoms/deficits into account, primarily related to muscle oxidative capacity in subjects with MS. Additional study is needed to further examine/verify these findings.

  11. Walking to school in Scotland: Do perceptions of neighbourhood quality matter?

    Directory of Open Access Journals (Sweden)

    E.O.D. Waygood

    2015-03-01

    Full Text Available A decrease in active travel has been observed over the past years in many Western countries including Scotland. A large part of this is likely due to the greater travel distances. However, previous research has suggested that perceptions of one's neighbourhood may also affect walking levels. If parents fear crime or traffic levels, or feel that their neighbourhood is of low quality they may not let their child walk. These perceptions are subjective and may be interlinked to each other. It is important to understand which perceptions matter more than others, in order to design the most suitable policy to promote more active travel behaviour among children. Using the Scottish Household Survey, this study investigates how or whether 48 different perceptions of neighbourhood quality or 11 reasons for having chosen their house affect children walking to school. A variable attrition method was used to reduce the number of variables for modelling. When walking distance, household characteristics, and built environment are included in a binary regression model only two perceptions were found to be significant: good local shops and slow/safe traffic. Implications of the findings are discussed.

  12. Distances to Dark Clouds: Comparing Extinction Distances to Maser Parallax Distances

    CERN Document Server

    Foster, Jonathan B; Benjamin, Robert A; Hoare, Melvin G; Jackson, James M

    2012-01-01

    We test two different methods of using near-infrared extinction to estimate distances to dark clouds in the first quadrant of the Galaxy using large near infrared (2MASS and UKIDSS) surveys. VLBI parallax measurements of masers around massive young stars provide the most direct and bias-free measurement of the distance to these dark clouds. We compare the extinction distance estimates to these maser parallax distances. We also compare these distances to kinematic distances, including recent re-calibrations of the Galactic rotation curve. The extinction distance methods agree with the maser parallax distances (within the errors) between 66% and 100% of the time (depending on method and input survey) and between 85% and 100% of the time outside of the crowded Galactic center. Although the sample size is small, extinction distance methods reproduce maser parallax distances better than kinematic distances; furthermore, extinction distance methods do not suffer from the kinematic distance ambiguity. This validatio...

  13. Sets avoiding integral distances

    CERN Document Server

    Kurz, Sascha

    2012-01-01

    We study open point sets in Euclidean spaces $\\mathbb{R}^d$ without a pair of points an integral distance apart. By a result of Furstenberg, Katznelson, and Weiss such sets must be of Lebesgue upper density zero. We are interested in how large such sets can be in $d$-dimensional volume. We determine the lower and upper bounds for the volumes of the sets in terms of the number of their connected components and dimension, and also give some exact values. Our problem can be viewed as a kind of inverse to known problems on sets with pairwise rational or integral distances.

  14. Distance Teaching on Bornholm

    DEFF Research Database (Denmark)

    Hansen, Finn J. S.; Clausen, Christian

    2001-01-01

    The case study represents an example of a top-down introduction of distance teaching as part of Danish trials with the introduction of multimedia in education. The study is concerned with the background, aim and context of the trial as well as the role and working of the technology and the organi......The case study represents an example of a top-down introduction of distance teaching as part of Danish trials with the introduction of multimedia in education. The study is concerned with the background, aim and context of the trial as well as the role and working of the technology...

  15. Activating and relaxing music entrains the speed of beat synchronized walking.

    Directory of Open Access Journals (Sweden)

    Marc Leman

    Full Text Available Inspired by a theory of embodied music cognition, we investigate whether music can entrain the speed of beat synchronized walking. If human walking is in synchrony with the beat and all musical stimuli have the same duration and the same tempo, then differences in walking speed can only be the result of music-induced differences in stride length, thus reflecting the vigor or physical strength of the movement. Participants walked in an open field in synchrony with the beat of 52 different musical stimuli all having a tempo of 130 beats per minute and a meter of 4 beats. The walking speed was measured as the walked distance during a time interval of 30 seconds. The results reveal that some music is 'activating' in the sense that it increases the speed, and some music is 'relaxing' in the sense that it decreases the speed, compared to the spontaneous walked speed in response to metronome stimuli. Participants are consistent in their observation of qualitative differences between the relaxing and activating musical stimuli. Using regression analysis, it was possible to set up a predictive model using only four sonic features that explain 60% of the variance. The sonic features capture variation in loudness and pitch patterns at periods of three, four and six beats, suggesting that expressive patterns in music are responsible for the effect. The mechanism may be attributed to an attentional shift, a subliminal audio-motor entrainment mechanism, or an arousal effect, but further study is needed to figure this out. Overall, the study supports the hypothesis that recurrent patterns of fluctuation affecting the binary meter strength of the music may entrain the vigor of the movement. The study opens up new perspectives for understanding the relationship between entrainment and expressiveness, with the possibility to develop applications that can be used in domains such as sports and physical rehabilitation.

  16. The Apollo Number: space suits, self-support, and the walk-run transition.

    Directory of Open Access Journals (Sweden)

    Christopher E Carr

    Full Text Available BACKGROUND: How space suits affect the preferred walk-run transition is an open question with relevance to human biomechanics and planetary extravehicular activity. Walking and running energetics differ; in reduced gravity (<0.5 g, running, unlike on Earth, uses less energy per distance than walking. METHODOLOGY/PRINCIPAL FINDINGS: The walk-run transition (denoted * correlates with the Froude Number (Fr = v(2/gL, velocity v, gravitational acceleration g, leg length L. Human unsuited Fr* is relatively constant (approximately 0.5 with gravity but increases substantially with decreasing gravity below approximately 0.4 g, rising to 0.9 in 1/6 g; space suits appear to lower Fr*. Because of pressure forces, space suits partially (1 g or completely (lunar-g support their own weight. We define the Apollo Number (Ap = Fr/M as an expected invariant of locomotion under manipulations of M, the ratio of human-supported to total transported mass. We hypothesize that for lunar suited conditions Ap* but not Fr* will be near 0.9, because the Apollo Number captures the effect of space suit self-support. We used the Apollo Lunar Surface Journal and other sources to identify 38 gait events during lunar exploration for which we could determine gait type (walk/lope/run and calculate Ap. We estimated the binary transition between walk/lope (0 and run (1, yielding Fr* (0.36+/-0.11, mean+/-95% CI and Ap* (0.68+/-0.20. CONCLUSIONS/SIGNIFICANCE: The Apollo Number explains 60% of the difference between suited and unsuited Fr*, appears to capture in large part the effects of space suits on the walk-run transition, and provides several testable predictions for space suit locomotion and, of increasing relevance here on Earth, exoskeleton locomotion. The knowledge of how space suits affect gait transitions can be used to optimize space suits for use on the Moon and Mars.

  17. Activating and Relaxing Music Entrains the Speed of Beat Synchronized Walking

    Science.gov (United States)

    Leman, Marc; Moelants, Dirk; Varewyck, Matthias; Styns, Frederik; van Noorden, Leon; Martens, Jean-Pierre

    2013-01-01

    Inspired by a theory of embodied music cognition, we investigate whether music can entrain the speed of beat synchronized walking. If human walking is in synchrony with the beat and all musical stimuli have the same duration and the same tempo, then differences in walking speed can only be the result of music-induced differences in stride length, thus reflecting the vigor or physical strength of the movement. Participants walked in an open field in synchrony with the beat of 52 different musical stimuli all having a tempo of 130 beats per minute and a meter of 4 beats. The walking speed was measured as the walked distance during a time interval of 30 seconds. The results reveal that some music is ‘activating’ in the sense that it increases the speed, and some music is ‘relaxing’ in the sense that it decreases the speed, compared to the spontaneous walked speed in response to metronome stimuli. Participants are consistent in their observation of qualitative differences between the relaxing and activating musical stimuli. Using regression analysis, it was possible to set up a predictive model using only four sonic features that explain 60% of the variance. The sonic features capture variation in loudness and pitch patterns at periods of three, four and six beats, suggesting that expressive patterns in music are responsible for the effect. The mechanism may be attributed to an attentional shift, a subliminal audio-motor entrainment mechanism, or an arousal effect, but further study is needed to figure this out. Overall, the study supports the hypothesis that recurrent patterns of fluctuation affecting the binary meter strength of the music may entrain the vigor of the movement. The study opens up new perspectives for understanding the relationship between entrainment and expressiveness, with the possibility to develop applications that can be used in domains such as sports and physical rehabilitation. PMID:23874469

  18. Distances to star forming regions

    CERN Document Server

    Loinard, Laurent

    2014-01-01

    The determination of accurate distances to star-forming regions are discussed in the broader historical context of astronomical distance measurements. We summarize recent results for regions within 1 kpc and present perspectives for the near and more distance future.

  19. Reference Values for the Six-Minute Walk Test in Healthy Children and Adolescents: a Systematic Review

    Directory of Open Access Journals (Sweden)

    Lucas de Assis Pereira Cacau

    Full Text Available Abstract Objective: The aim of the study is to compare the available reference values and the six-minute walk test equations in healthy children/adolescents. Our systematic review was planned and performed in accordance with the PRISMA guidelines. We included all studies that established reference values for the six-minute walk test in healthy children/adolescents. Methods: To perform this review, a research was performed in PubMed, EMBASE (via SCOPUS and Cochrane (LILACS, Bibliographic Index Spanish in Health Sciences, Organization Collection Pan-American Health Organization, Publications of the World Health Organization and Scientific Electronic Library Online (SciELO via Virtual Health Library until June 2015 without language restriction. Results: The initial research identified 276 abstracts. Twelve studies met the inclusion criteria and were fully reviewed and approved by both reviewers. None of the selected studies presented sample size calculation. Most of the studies recruited children and adolescents from school. Six studies reported the use of random samples. Most studies used a corridor of 30 meters. All studies followed the American Thoracic Society guidelines to perform the six-minute walk test. The walked distance ranged 159 meters among the studies. Of the 12 included studies, 7 (58% reported descriptive data and 6 (50% established reference equation for the walked distance in the six-minute walk test. Conclusion: The reference value for the six-minute walk test in children and adolescents ranged substantially from studies in different countries. A reference equation was not provided in all studies, but the ones available took into account well established variables in the context of exercise performance, such as height, heart rate, age and weight. Countries that did not established reference values for the six-minute walk test should be encouraged to do because it would help their clinicians and researchers have a more precise

  20. Reference Values for the Six-Minute Walk Test in Healthy Children and Adolescents: a Systematic Review

    Science.gov (United States)

    Cacau, Lucas de Assis Pereira; de Santana-Filho, Valter Joviniano; Maynard, Luana G.; Gomes Neto, Mansueto; Fernandes, Marcelo; Carvalho, Vitor Oliveira

    2016-01-01

    Objective The aim of the study is to compare the available reference values and the six-minute walk test equations in healthy children/adolescents. Our systematic review was planned and performed in accordance with the PRISMA guidelines. We included all studies that established reference values for the six-minute walk test in healthy children/adolescents. Methods To perform this review, a research was performed in PubMed, EMBASE (via SCOPUS) and Cochrane (LILACS), Bibliographic Index Spanish in Health Sciences, Organization Collection Pan-American Health Organization, Publications of the World Health Organization and Scientific Electronic Library Online (SciELO) via Virtual Health Library until June 2015 without language restriction. Results The initial research identified 276 abstracts. Twelve studies met the inclusion criteria and were fully reviewed and approved by both reviewers. None of the selected studies presented sample size calculation. Most of the studies recruited children and adolescents from school. Six studies reported the use of random samples. Most studies used a corridor of 30 meters. All studies followed the American Thoracic Society guidelines to perform the six-minute walk test. The walked distance ranged 159 meters among the studies. Of the 12 included studies, 7 (58%) reported descriptive data and 6 (50%) established reference equation for the walked distance in the six-minute walk test. Conclusion The reference value for the six-minute walk test in children and adolescents ranged substantially from studies in different countries. A reference equation was not provided in all studies, but the ones available took into account well established variables in the context of exercise performance, such as height, heart rate, age and weight. Countries that did not established reference values for the six-minute walk test should be encouraged to do because it would help their clinicians and researchers have a more precise interpretation of the test

  1. Quantum walk public-key cryptographic system

    Science.gov (United States)

    Vlachou, C.; Rodrigues, J.; Mateus, P.; Paunković, N.; Souto, A.

    2015-12-01

    Quantum Cryptography is a rapidly developing field of research that benefits from the properties of Quantum Mechanics in performing cryptographic tasks. Quantum walks are a powerful model for quantum computation and very promising for quantum information processing. In this paper, we present a quantum public-key cryptographic system based on quantum walks. In particular, in the proposed protocol the public-key is given by a quantum state generated by performing a quantum walk. We show that the protocol is secure and analyze the complexity of public key generation and encryption/decryption procedures.

  2. An experimental analysis of human straight walking

    Science.gov (United States)

    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.

  3. Elements of random walk and diffusion processes

    CERN Document Server

    Ibe, Oliver C

    2013-01-01

    Presents an important and unique introduction to random walk theory Random walk is a stochastic process that has proven to be a useful model in understanding discrete-state discrete-time processes across a wide spectrum of scientific disciplines. Elements of Random Walk and Diffusion Processes provides an interdisciplinary approach by including numerous practical examples and exercises with real-world applications in operations research, economics, engineering, and physics. Featuring an introduction to powerful and general techniques that are used in the application of physical and dynamic

  4. Limit cycle walking on a regularized ground

    CERN Document Server

    Jacobs, Henry O

    2012-01-01

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

  5. [Walking assist robot and its clinical application].

    Science.gov (United States)

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

    2009-06-01

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

  6. Scaling of random walk betweenness in networks

    CERN Document Server

    Narayan, O

    2016-01-01

    The betweenness centrality of graphs using random walk paths instead of geodesics is studied. A scaling collapse with no adjustable parameters is obtained as the graph size $N$ is varied; the scaling curve depends on the graph model. A normalized random betweenness, that counts each walk passing through a node only once, is also defined. It is argued to be more useful and seen to have simpler scaling behavior. In particular, the probability for a random walk on a preferential attachment graph to pass through the root node is found to tend to unity as $N\\rightarrow\\infty.$

  7. Exponential algorithmic speedup by quantum walk

    CERN Document Server

    Childs, A M; Deotto, E; Farhi, E; Gutmann, S; Spielman, D A; Childs, Andrew M.; Cleve, Richard; Deotto, Enrico; Farhi, Edward; Gutmann, Sam; Spielman, Daniel A.

    2002-01-01

    We construct an oracular problem that can be solved exponentially faster on a quantum computer than on a classical computer. The quantum algorithm is based on a continuous time quantum walk, and thus employs a different technique from previous quantum algorithms based on quantum Fourier transforms. We show how to implement the quantum walk efficiently in our oracular setting. We then show how this quantum walk can be used to solve our problem by rapidly traversing a graph. Finally, we prove that no classical algorithm can solve this problem with high probability in subexponential time.

  8. Tiger beetle's pursuit of prey depends on distance

    Science.gov (United States)

    Noest, Robert; Wang, Jane

    2015-03-01

    Tiger beetles are fast predators capable of chasing prey under closed-loop visual guidance. We investigated their control system using high-speed digital recordings of beetles chasing a moving prey dummy in a laboratory arena. Analysis reveals that the beetle uses a proportional control law in which the angular position of the prey relative to the beetle's body axis drives the beetle's angular velocity with a delay of about 28 ms. The system gain is shown to depend on the beetle-prey distance in a pattern indicating three hunting phases over the observed distance domain. We show that to explain this behavior the tiger beetle must be capable of visually determining the distance to its target and using that to adapt the gain in its proportional control law. We will end with a discussion on the possible methods for distance detection by the tiger beetle and focus on two of them. Motion parallax, using the natural head sway induced by the walking gait of the tiger beetle, is shown to have insufficient distance range. However elevation in the field of vision, using the angle with respect to the horizon at which a target is observed, has a much larger distance range and is a prime candidate for the mechanism of visual distance detection in the tiger beetle.

  9. Human-mediated dispersal of seeds over long distances

    Science.gov (United States)

    Wichmann, Matthias C.; Alexander, Matt J.; Soons, Merel B.; Galsworthy, Stephen; Dunne, Laura; Gould, Robert; Fairfax, Christina; Niggemann, Marc; Hails, Rosie S.; Bullock, James M.

    2008-01-01

    Human activities have fundamental impacts on the distribution of species through altered land use, but also directly by dispersal of propagules. Rare long-distance dispersal events have a disproportionate importance for the spread of species including invasions. While it is widely accepted that humans may act as vectors of long-distance dispersal, there are few studies that quantify this process. We studied in detail a mechanism of human-mediated dispersal (HMD). For two plant species we measured, over a wide range of distances, how many seeds are carried by humans on shoes. While over half of the seeds fell off within 5 m, seeds were regularly still attached to shoes after 5 km. Semi-mechanistic models were fitted, and these suggested that long-distance dispersal on shoes is facilitated by decreasing seed detachment probability with distance. Mechanistic modelling showed that the primary vector, wind, was less important as an agent of long-distance dispersal, dispersing seeds less than 250 m. Full dispersal kernels were derived by combining the models for primary dispersal by wind and secondary dispersal by humans. These suggest that walking humans can disperse seeds to very long distances, up to at least 10 km, and provide some of the first quantified dispersal kernels for HMD. PMID:18826932

  10. How many walking and cycling trips made by elderly are beyond commonly used buffer sizes: Results from a GPS study

    NARCIS (Netherlands)

    Prins, R.G.; Pierik, F.; Etman, A.; Sterkenburg, R.P.; Kamphuis, C.B.M.; Lenthe, F.J. van

    2014-01-01

    In choosing appropriate buffer sizes to study environmental influences on physical activity, studies are hampered by insufficient insight into the distance elderly travel actively. This study aims at getting insight into the number of trips walked and cycled within various buffer sizes using GPS mea

  11. Signaling Over Distances.

    Science.gov (United States)

    Saito, Atsushi; Cavalli, Valeria

    2016-02-01

    Neurons are extremely polarized cells. Axon lengths often exceed the dimension of the neuronal cell body by several orders of magnitude. These extreme axonal lengths imply that neurons have mastered efficient mechanisms for long distance signaling between soma and synaptic terminal. These elaborate mechanisms are required for neuronal development and maintenance of the nervous system. Neurons can fine-tune long distance signaling through calcium wave propagation and bidirectional transport of proteins, vesicles, and mRNAs along microtubules. The signal transmission over extreme lengths also ensures that information about axon injury is communicated to the soma and allows for repair mechanisms to be engaged. This review focuses on the different mechanisms employed by neurons to signal over long axonal distances and how signals are interpreted in the soma, with an emphasis on proteomic studies. We also discuss how proteomic approaches could help further deciphering the signaling mechanisms operating over long distance in axons. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  12. Weighted Feature Distance

    DEFF Research Database (Denmark)

    Ortiz-Arroyo, Daniel; Yazdani, Hossein

    2017-01-01

    The accuracy of machine learning methods for clustering depends on the optimal selection of similarity functions. Conventional distance functions for the vector space might cause an algorithm to being affected by some dominant features that may skew its final results. This paper introduces a flexib...

  13. Encyclopedia of Distance Learning

    Science.gov (United States)

    Howard, Caroline, Ed.; Boettecher, Judith, Ed.; Justice, Lorraine, Ed.; Schenk, Karen, Ed.; Rogers, Patricia, Ed.; Berg, Gary, Ed.

    2005-01-01

    The innovations in computer and communications technologies combined with on-going needs to deliver educational programs to students regardless of their physical locations, have lead to the innovation of distance education programs and technologies. To keep up with recent developments in both areas of technologies and techniques related to…

  14. Accreditation of Distance Learning

    Science.gov (United States)

    Demirel, Ergün

    2016-01-01

    The higher education institutes aspire to gain reputation of quality having accreditation from internationally recognized awarding bodies. The accreditation leads and provides quality assurance for education. Although distance learning becomes a significant part of the education system in the 21st century, there is still a common opinion that the…

  15. Prospect of Distance Learning

    Science.gov (United States)

    Rahman, Monsurur; Karim, Reza; Byramjee, Framarz

    2015-01-01

    Many educational institutions in the United States are currently offering programs through distance learning, and that trend is rising. In almost all spheres of education a developing country like Bangladesh needs to make available the expertise of the most qualified faculty to her distant people. But the fundamental question remains as to whether…

  16. Rapport in Distance Education

    Science.gov (United States)

    Murphy, Elizabeth; Rodriguez-Manzanares, Maria A.

    2012-01-01

    Rapport has been recognized as important in learning in general but little is known about its importance in distance education (DE). The study we report on in this paper provides insights into the importance of rapport in DE as well as challenges to and indicators of rapport-building in DE. The study relied on interviews with 42 Canadian…

  17. Misconceptions of Astronomical Distances

    Science.gov (United States)

    Miller, Brian W.; Brewer, William F.

    2010-01-01

    Previous empirical studies using multiple-choice procedures have suggested that there are misconceptions about the scale of astronomical distances. The present study provides a quantitative estimate of the nature of this misconception among US university students by asking them, in an open-ended response format, to make estimates of the distances…

  18. Detection of gait cycles in treadmill walking using a Kinect.

    Science.gov (United States)

    Auvinet, Edouard; Multon, Franck; Aubin, Carl-Eric; Meunier, Jean; Raison, Maxime

    2015-02-01

    Treadmill walking is commonly used to analyze several gait cycles in a limited space. Depth cameras, such as the low-cost and easy-to-use Kinect sensor, look promising for gait analysis on a treadmill for routine outpatient clinics. However, gait analysis is based on accurately detecting gait events (such as heel-strike) by tracking the feet which may be incorrectly recognized with Kinect. Indeed depth images could lead to confusion between the ground and the feet around the contact phase. To tackle this problem we assume that heel-strike events could be indirectly estimated by searching for extreme values of the distance between knee joints along the walking longitudinal axis. To evaluate this assumption, the motion of 11 healthy subjects walking on a treadmill was recorded using both an optoelectronic system and Kinect. The measures were compared to reference heel-strike events obtained with vertical foot velocity. When using the optoelectronic system to assess knee joints, heel-strike estimation errors were very small (29±18ms) leading to small cycle durations errors (0±15ms). To locate knees in depth map (Kinect), we used anthropometrical data to select the body point located at a constant height where the knee should be based on a reference posture. This Kinect approach gave heel-strike errors of 17±24ms (mean cycle duration error: 0±12ms). Using this same anthropometric methodology with optoelectronic data, the heel-strike error was 12±12ms (mean cycle duration error: 0±11ms). Compared to previous studies using Kinect, heel-strike and gait cycles were more accurately estimated, which could improve clinical gait analysis with such sensor.

  19. Design of a walking robot

    Science.gov (United States)

    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.

  20. Holographic walking from tachyon DBI

    Energy Technology Data Exchange (ETDEWEB)

    Kutasov, David [EFI and Department of Physics, University of Chicago, 5640 S. Ellis Av., Chicago, IL 60637 (United States); Lin, Jennifer, E-mail: jenlin@uchicago.edu [EFI and Department of Physics, University of Chicago, 5640 S. Ellis Av., Chicago, IL 60637 (United States); Parnachev, Andrei [Institute Lorentz for Theoretical Physics, Leiden University, PO Box 9506, Leiden 2300RA (Netherlands)

    2012-10-11

    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{sub n}{approx}n; in the soft wall case we exhibit potentials with m{sub n}{approx}n{sup {alpha}}, 0<{alpha} Less-Than-Or-Slanted-Equal-To 1/2. 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.

  1. Community walking in people with Parkinson's disease.

    Science.gov (United States)

    Lamont, Robyn M; Morris, Meg E; Woollacott, Marjorie H; Brauer, Sandra G

    2012-01-01

    People with Parkinson's disease often have walking difficulty, and this is likely to be exacerbated while walking in places in the community, where people are likely to face greater and more varied challenges. This study aims to understand the facilitators and the barriers to walking in the community perceived by people with Parkinson's disease. This qualitative study involved 5 focus groups (n = 34) of people with Parkinson's disease and their partners residing in metropolitan and rural regions in Queensland, Australia. Results found that people with PD reported to use internal personal strategies as facilitators to community walking, but identified primarily external factors, particularly the environmental factors as barriers. The adoption of strategies or the use of facilitators allows people with Parkinson's disease to cope so that participants often did not report disability.

  2. Locomotor sequence learning in visually guided walking

    DEFF Research Database (Denmark)

    Choi, Julia T; Jensen, Peter; Nielsen, Jens Bo

    2016-01-01

    walking. In addition, we determined how age (i.e., healthy young adults vs. children) and biomechanical factors (i.e., walking speed) affected the rate and magnitude of locomotor sequence learning. The results showed that healthy young adults (age 24 ± 5 years, N = 20) could learn a specific sequence...... of step lengths over 300 training steps. Younger children (age 6-10 years, N = 8) have lower baseline performance, but their magnitude and rate of sequence learning was the same compared to older children (11-16 years, N = 10) and healthy adults. In addition, learning capacity may be more limited...... at faster walking speeds. To our knowledge, this is the first study to demonstrate that spatial sequence learning can be integrated with a highly automatic task like walking. These findings suggest that adults and children use implicit knowledge about the sequence to plan and execute leg movement during...

  3. Database of Standardized Questionnaires About Walking & Bicycling

    Science.gov (United States)

    This database contains questionnaire items and a list of validation studies for standardized items related to walking and biking. The items come from multiple national and international physical activity questionnaires.

  4. Second syzygies of monomial submodules from walks

    CERN Document Server

    Craw, Alastair

    2011-01-01

    We present an explicit and especially simple filtration on the module of syzygies of a monomial submodule. Our main tool is the description of generators of the module of second syzygies in terms of walks in a complete graph.

  5. Levy random walks on multiplex networks

    CERN Document Server

    Guo, Quantong; Zheng, Zhiming; Moreno, Yamir

    2016-01-01

    Random walks constitute a fundamental mechanism for many dynamics taking place on complex networks. Besides, as a more realistic description of our society, multiplex networks have been receiving a growing interest, as well as the dynamical processes that occur on top of them. Here, inspired by one specific model of random walks that seems to be ubiquitous across many scientific fields, the Levy flight, we study a new navigation strategy on top of multiplex networks. Capitalizing on spectral graph and stochastic matrix theories, we derive analytical expressions for the mean first passage time and the average time to reach a node on these networks. Moreover, we also explore the efficiency of Levy random walks, which we found to be very different as compared to the single layer scenario, accounting for the structure and dynamics inherent to the multiplex network. Finally, by comparing with some other important random walk processes defined on multiplex networks, we find that in some region of the parameters, a ...

  6. Sensitivity Study of Stochastic Walking Load Models

    DEFF Research Database (Denmark)

    Pedersen, Lars; Frier, Christian

    2010-01-01

    On flexible structures such as footbridges and long-span floors, walking loads may generate excessive structural vibrations and serviceability problems. The problem is increasing because of the growing tendency to employ long spans in structural design. In many design codes, the vibration...... serviceability limit state is assessed using a walking load model in which the walking parameters are modelled deterministically. However, the walking parameters are stochastic (for instance the weight of the pedestrian is not likely to be the same for every footbridge crossing), and a natural way forward...... investigates whether statistical distributions of bridge response are sensitive to some of the decisions made by the engineer doing the analyses. For the paper a selected part of potential influences are examined and footbridge responses are extracted using Monte-Carlo simulations and focus is on estimating...

  7. Chaos game representation (CGR)-walk model for DNA sequences

    Institute of Scientific and Technical Information of China (English)

    Gao Jie; Xu Zhen-Yuan

    2009-01-01

    Chaos game representation (CGR) is an iterative mapping technique that processes sequences of units, such as nucleotides in a DNA sequence or amino acids in a protein, in order to determine the coordinates of their positions in a continuous space. This distribution of positions has two features: one is unique, and the other is source sequence that can be recovered from the coordinates so that the distance between positions may serve as a measure of similarity between the corresponding sequences. A CGR-walk model is proposed based on CGR coordinates for the DNA sequences. The CGR coordinates are converted into a time series, and a long-memory ARFIMA (p, d, q) model, where ARFIMA stands for autoregressive fractionally integrated moving average, is introduced into the DNA sequence analysis. This model is applied to simulating real CGR-walk sequence data of ten genomic sequences. Remarkably long-range correlations are uncovered in the data, and the results from these models are reasonably fitted with those from the ARFIMA (p, d, q) model.

  8. Symmetricity of Distribution for One-Dimensional Hadamard Walk

    CERN Document Server

    Konno, N; Soshi, T; Konno, Norio; Namiki, Takao; Soshi, Takahiro

    2002-01-01

    In this paper we study a one-dimensional quantum random walk with the Hadamard transformation which is often called the Hadamard walk. We construct the Hadamard walk using a transition matrix on probability amplitude and give some results on symmetricity of probability distributions for the Hadamard walk.

  9. Variability and stability analysis of walking of transfemoral amputees

    NARCIS (Netherlands)

    Lamoth, Claudine C.; Ainsworth, Erik; Polomski, Wojtek; Houdijk, Han

    2010-01-01

    Variability and stability of walking of eight transfemoral amputees and eight healthy controls was studied under four conditions walking inside on a smooth terrain walking while performing a dual-task and walking outside on (ir)regular surfaces Trunk accelerations were recorded with a tri-axial acce

  10. Urban Walking and the Pedagogies of the Street

    Science.gov (United States)

    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…

  11. Does getting a dog increase recreational walking?

    Directory of Open Access Journals (Sweden)

    Knuiman Matthew W

    2008-03-01

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

  12. Walking as a social practice: dispersed walking and the organisation of everyday practices.

    Science.gov (United States)

    Harries, Tim; Rettie, Ruth

    2016-07-01

    This paper uses social practice theory to study the interweaving of walking into everyday practices and considers how greater awareness of everyday walking can influence its position within the organisation and scheduling of everyday life. Walking is of policy interest because of its perceived benefits for health. This paper asserts that increased awareness of everyday walking allows users to become more active without having to reschedule existing activities. Using Schatzki's distinction between dispersed and integrative practices, it argues that increasing awareness of dispersed walking can enlist walking into the teleoaffective organisation of some social practices and prompt the performance of new 'health practices' within everyday domains of life such as shopping and employment. While this analysis offers useful insights for the design of behaviour change strategies, it also points to some unintended consequences of using digital feedback to increase walking awareness. In directing the gaze of participants at one particular element of their daily practices, the paper suggests, digital walking feedback provides a 'partial' view of practices: by highlighting the exercise value of walking at the expense of other values it can prompt feedback recipients to pass moral judgements on themselves based on this partial view. A Virtual Abstract of this paper can be found at: https://youtu.be/WV7DUnKD5Mw. © 2016 Foundation for the Sociology of Health & Illness.

  13. Walking on high heels changes muscle activity and the dynamics of human walking significantly

    DEFF Research Database (Denmark)

    Simonsen, Erik Bruun; Svendsen, Morten B; Nørreslet, Andreas

    2012-01-01

    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...... 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...

  14. Hesitant avoidance while walking: an error of social behavior generated by mutual interaction

    Directory of Open Access Journals (Sweden)

    Motoyasu eHonma

    2015-07-01

    Full Text Available Altering physical actions when responding to changing environmental demands is important but not always effectively performed. This ineffectiveness, which is an error of social behavior generated by mutual interactions, is not well understood. This study investigated mechanisms of a hesitant behavior that occurs in people walking toward each other, causing people to move in the same direction when attempting to avoid a collision. Using a motion capture device affixed to 17 pairs, we first confirmed the hesitant behavior by a difference between the experimental task, which involved an indeterminate situation to assess the actions of another individual, and the control task, which involved a predetermined avoiding direction, in a real-time situation involving two people. We next investigated the effect of three external factors: long distance until an event, synchronized walking cycle, and different foot relations in dyads on the hesitant behavior. A dramatic increase in freezing and near-collision behavior occurred in dyads for which the avoiding direction was not predetermined. The behavior related with the combination of long distance until an event, synchronized walking cycle, and different foot relations in dyads. We found that the hesitant behavior is influenced by an interpersonal relationship under enough distance to predict other movement. The hesitant behavior has possibly emerged as an undesired by-product of joint action. These results contribute to our understanding of the mechanisms of adaptive control of perception-action coupling in mutual interaction.

  15. Hesitant avoidance while walking: an error of social behavior generated by mutual interaction.

    Science.gov (United States)

    Honma, Motoyasu; Koyama, Shinichi; Kawamura, Mitsuru

    2015-01-01

    Altering physical actions when responding to changing environmental demands is important but not always effectively performed. This ineffectiveness, which is an error of social behavior generated by mutual interactions, is not well understood. This study investigated mechanisms of a hesitant behavior that occurs in people walking toward each other, causing people to move in the same direction when attempting to avoid a collision. Using a motion capture device affixed to 17 pairs, we first confirmed the hesitant behavior by a difference between the experimental task, which involved an indeterminate situation to assess the actions of another individual, and the control task, which involved a predetermined avoiding direction, in a real-time situation involving two people. We next investigated the effect of three external factors: long distance until an event, synchronized walking cycle, and different foot relations in dyads on the hesitant behavior. A dramatic increase in freezing and near-collision behavior occurred in dyads for which the avoiding direction was not predetermined. The behavior related with the combination of long distance until an event, synchronized walking cycle, and different foot relations in dyads. We found that the hesitant behavior is influenced by an interpersonal relationship under enough distance to predict other movement. The hesitant behavior has possibly emerged as an undesired by-product of joint action. These results contribute to our understanding of the mechanisms of adaptive control of perception-action coupling in mutual interaction.

  16. Motor imagery for walking: a comparison between cerebral palsy adolescents with hemiplegia and diplegia.

    Science.gov (United States)

    Molina, Michèle; Kudlinski, Cyril; Guilbert, Jessica; Spruijt, Steffie; Steenbergen, Bert; Jouen, François

    2015-02-01

    The goal of the study was to investigate whether motor imagery (MI) could be observed in cerebral palsy (CP) participants presenting a bilateral affected body side (diplegia) as it has been previously revealed in participants presenting a unilateral body affected sided (hemiplegia). MI capacity for walking was investigated in CP adolescents diagnosed with hemiplegia (n=10) or diplegia (n=10) and in adolescents with typical motor development (n=10). Participants were explicitly asked to imagine walking before and after actually walking toward a target located at 4 m and 8 m. Movement durations for executed and imagined trials were recorded. ANOVA and Pearson's correlation analyses revealed the existence of time invariance between executed and imagined movement durations for the control group and both groups of CP participants. However, results revealed that MI capacity in CP participants was observed for the short distance (4 m) but not for the long distance (8 m). Moreover, even for short distance, CP participants performed worse than typical adolescents. These results are discussed inline of recent researches suggesting that MI in CP participants may not depend on the side of the lesion.

  17. The Snail Takes a Walk with Me

    Institute of Scientific and Technical Information of China (English)

    王宜鸣; 乐伟国

    2008-01-01

    @@ 一、故事内容 I'm a snake. Today God gives me a job-I should take a walk with the snail. The snail moves too slowly. I have to scare him. He looks at me, full of shame. I am very angry. I pull him, and even kick.The snail cries, so he stops walking. I feel quite helpless.

  18. Effect of Body Composition on Walking Economy

    OpenAIRE

    Maciejczyk Marcin; Wiecek Magdalena; Szymura Jadwiga; Szygula Zbigniew

    2016-01-01

    Purpose. The aim of the study was to evaluate walking economy and physiological responses at two walking speeds in males with similar absolute body mass but different body composition. Methods. The study involved 22 young men with similar absolute body mass, BMI, aerobic performance, calf and thigh circumference. The participants differed in body composition: body fat (HBF group) and lean body mass (HLBM group). In the graded test, maximal oxygen uptake (VO2max) and maximal heart rate were me...

  19. Age-related differences in walking stability.

    Science.gov (United States)

    Menz, Hylton B; Lord, Stephen R; Fitzpatrick, Richard C

    2003-03-01

    a large proportion of falls in older people occur when walking; however the mechanisms underlying impaired balance during gait are poorly understood. to evaluate acceleration patterns at the head and pelvis in young and older subjects when walking on a level and an irregular walking surface, in order to develop an understanding of how ageing affects postural responses to challenging walking conditions. temporo-spatial gait parameters and variables derived from acceleration signals were recorded in 30 young people aged 22-39 years (mean 29.0, SD 4.3), and 30 older people with a low risk of falling aged 75-85 years (mean 79.0, SD 3.0) while walking on a level and an irregular walking surface. Subjects also underwent tests of vision, sensation, strength, reaction time and balance. older subjects exhibited a more conservative gait pattern, characterised by reduced velocity, shorter step length and increased step timing variability. These differences were particularly pronounced when walking on the irregular surface. The magnitude of accelerations at the head and pelvis were generally smaller in older subjects; however the smoothness of the acceleration signals did not differ between the two groups. Older subjects performed worse on tests of vision, peripheral sensation, strength, reaction time and balance. the adoption of a more conservative basic gait pattern by older people with a low risk of falling reduces the magnitude of accelerations experienced by the head and pelvis when walking, which is likely to be a compensatory strategy to maintain balance in the presence of age-related deficits in physiological function, particularly reduced lower limb strength.

  20. On a directionally reinforced random walk

    CERN Document Server

    Ghosh, Arka; Roitershtein, Alexander

    2011-01-01

    We consider a generalized version of a directionally reinforced random walk, which was originally introduced by Mauldin, Monticino, and von Weizs\\"{a}cker in \\cite{drw}. Our main result is a stable limit theorem for the position of the random walk in higher dimensions. This extends a result of Horv\\'{a}th and Shao \\cite{limits} that was previously obtained in dimension one only (however, in a more stringent functional form).

  1. Feedback control system for walking in man.

    Science.gov (United States)

    Petrofsky, J S; Phillips, C A; Heaton, H H

    1984-01-01

    A computer control stimulation system is described which has been successfully tested by allowing a paraplegic subject to stand and walk through closed loop control. This system is a Z80 microprocessor system with eight channels of analog to digital and 16 channels of digital to analog control. Programming is written in CPM and works quite successfully for maintaining lower body postural control in paraplegics. Further expansion of this system would enable a feedback control system for multidirectional walking in man.

  2. Strongly Correlated Quantum Walks in Optical Lattices

    OpenAIRE

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

    2014-01-01

    Full control over the dynamics of interacting, indistinguishable quantum particles is an important prerequisite for the experimental study of strongly correlated quantum matter and the implementation of high-fidelity quantum information processing. Here we demonstrate such control over the quantum walk - the quantum mechanical analogue of the classical random walk - in the strong interaction regime. Using interacting bosonic atoms in an optical lattice, we directly observe fundamental effects...

  3. More Adults Are Walking PSA (:60)

    Centers for Disease Control (CDC) Podcasts

    2012-07-31

    This 60 second PSA is based on the August 2012 CDC Vital Signs report. While more adults are walking, only half get the recommended amount of physical activity. Listen to learn how communities, employers, and individuals may help increase walking.  Created: 7/31/2012 by Centers for Disease Control and Prevention (CDC).   Date Released: 8/7/2012.

  4. Go Naked: Diapers Affect Infant Walking

    OpenAIRE

    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 walking is adversely affected by old-fashioned cloth diapers, and that even modern disposable diapers—habitually worn by most infants in the sample—incur...

  5. Momentum Dynamics of One Dimensional Quantum Walks

    CERN Document Server

    Fuss, I; Sherman, P J; Naguleswaran, S; Fuss, Ian; White, langord B.; Sherman, Peter J.; Naguleswaran, Sanjeev

    2006-01-01

    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.

  6. Balancing of the anthropomorphous robot walking

    Science.gov (United States)

    Devaev, V. M.; Nikitina, D. V.; Fadeev, A. Y.

    2016-06-01

    Anthropomorphic robots are designed a human environment operates: buildings and structures, cabs and etc. The movement of these robots is carried out by walking which provides high throughput to overcome natural and manmade obstacles. The article presents some algorithm results for dynamic walking on the anthropomorphic robot AR601 example. The work is performed according to the Russian Government Program of Competitive Growth of Kazan Federal University.

  7. Adaptive Levy walks in foraging fallow deer.

    Directory of Open Access Journals (Sweden)

    Stefano Focardi

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

  8. Factors associated with daily walking of dogs

    OpenAIRE

    Westgarth, Carri; Christian, Hayley E; Christley, Robert M

    2015-01-01

    Background Regular physical activity is beneficial to the health of both people and animals. The role of regular exercise undertaken together, such as dog walking, is a public health interest of mutual benefit. Exploration of barriers and incentives to regular dog walking by owners is now required so that effective interventions to promote it can be designed. This study explored a well-characterised cross-sectional dataset of 276 dogs and owners from Cheshire, UK, for evidence of factors asso...

  9. Walking Out of the Family Towards Rights

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    WALKING in any city or ruralarea in China today, one will seewomen with confidence andpride, with their own work and lives.There is not much difference between theurban and rural women in dress. Theirfaces portray contentment and happiness.These are significant changes which havebeen brought about by women walking outof the family over the past near 50 years,and getting involved in society, alteringtheir dependence on men and making thempeople of dignity. The government knew clearly that to

  10. A Walk in the Semantic Park

    DEFF Research Database (Denmark)

    Danvy, Olivier; Johannsen, Jacob; Zerny, Ian

    2011-01-01

    To celebrate the 20th anniversary of PEPM, we are inviting you to a walk in the semantic park and to inter-derive reduction-based and reduction-free negational normalization functions.......To celebrate the 20th anniversary of PEPM, we are inviting you to a walk in the semantic park and to inter-derive reduction-based and reduction-free negational normalization functions....

  11. Is asymptomatic peripheral arterial disease associated with walking endurance in patients with COPD?

    Directory of Open Access Journals (Sweden)

    Sun KS

    2015-07-01

    Full Text Available Kuo-Shao Sun,1,2* Ming-Shian Lin,1,2* Yi-Jen Chen,1,2 Yih-Yuan Chen,3 Solomon Chih-Cheng Chen,4 Wei Chen1,5,6 1Division of Pulmonary and Critical Care Medicine, 2Department of Respiratory Care, Chang Gung University of Science and Technology, 3Department of Internal Medicine, 4Department of Medical Research, Ditmanson Medical Foundation Chia-Yi Christian Hospital, Chiayi, 5College of Nursing, Dayeh University, Changhua, 6Department of Respiratory Therapy, China Medical University, Taichung, Taiwan, Republic of China *These authors contributed equally to this work Objective: Symptomatic peripheral arterial disease (PAD is associated with impaired walking endurance in patients with chronic obstructive pulmonary disease (COPD. However, it is unknown whether asymptomatic PAD is associated with impaired walking endurance in patients with COPD. Methods: This prospective cross-sectional study enrolled 200 COPD patients (mean age: 70.9 years who volunteered to perform ankle-brachial index (ABI and 6-minute walk test (6MWT consecutively. Demographic data, lung function, dyspnea scales, and cardiovascular risk factors were recorded. The ABI was used to detect PAD (ABI <0.90. All patients were free of PAD symptoms at enrollment. Results: Of the 200 COPD patients, 17 (8.5% were diagnosed with asymptomatic PAD. The COPD patients without asymptomatic PAD did not walk significantly further on the 6MWT than the COPD patients with asymptomatic PAD (439±86 m vs 408±74 m, P=0.159. The strongest correlation with the distance walked on the 6MWT was Medical Research Council dyspnea scale (r2=-0.667, P<0.001, followed by oxygen-cost diagram (r2=0.582, P<0.001 and forced expiratory volume in 1 second (r2=0.532, P<0.001. In multivariate linear regression analysis, only age, forced expiratory volume in 1 second, and baseline pulse oximetry were independently correlated with the distance covered on the 6MWT (P<0.05. However, body mass index, baseline heart rate, and

  12. Mixing and decoherence in continuous-time quantum walks on long-range interacting cycles

    Energy Technology Data Exchange (ETDEWEB)

    Salimi, S; Radgohar, R [Faculty of Science, Department of Physics, University of Kurdistan, Pasdaran Ave., Sanandaj (Iran, Islamic Republic of)], E-mail: shsalimi@uok.ac.ir, E-mail: r.radgohar@uok.ac.ir

    2009-11-27

    We study the effect of small decoherence in continuous-time quantum walks on long-range interacting cycles, which are constructed by connecting all the two nodes of distance m on the cycle graph. In our investigation, each node is continuously monitored by an individual point contact, which induces the decoherence process. We obtain the analytical probability distribution and the mixing time upper bound. Our results show that, for small rates of decoherence, the mixing time upper bound is independent of distance parameter m and is proportional to inverse of decoherence rate.

  13. Statistics at the tip of a branching random walk and the delay of traveling waves

    Science.gov (United States)

    Brunet, É.; Derrida, B.

    2009-09-01

    We study the limiting distribution of particles at the frontier of a branching random walk. The positions of these particles can be viewed as the lowest energies of a directed polymer in a random medium in the mean-field case. We show that the average distances between these leading particles can be computed as the delay of a traveling wave evolving according to the Fisher-KPP front equation. These average distances exhibit universal behaviors, different from those of the probability cascades studied recently in the context of mean-field spin-glasses.

  14. A simplified analytical random walk model for proton dose calculation

    Science.gov (United States)

    Yao, Weiguang; Merchant, Thomas E.; Farr, Jonathan B.

    2016-10-01

    We propose an analytical random walk model for proton dose calculation in a laterally homogeneous medium. A formula for the spatial fluence distribution of primary protons is derived. The variance of the spatial distribution is in the form of a distance-squared law of the angular distribution. To improve the accuracy of dose calculation in the Bragg peak region, the energy spectrum of the protons is used. The accuracy is validated against Monte Carlo simulation in water phantoms with either air gaps or a slab of bone inserted. The algorithm accurately reflects the dose dependence on the depth of the bone and can deal with small-field dosimetry. We further applied the algorithm to patients’ cases in the highly heterogeneous head and pelvis sites and used a gamma test to show the reasonable accuracy of the algorithm in these sites. Our algorithm is fast for clinical use.

  15. Design with the feet: walking methods and participatory design

    DEFF Research Database (Denmark)

    Kanstrup, Anne Marie; Bertelsen, Pernille; Madsen, Jacob Østergaard

    2014-01-01

    This paper presents an analysis of walking methods and their relation to participatory design (PD). The paper includes a study of walking methods found in the literature and an empirical study of transect walks in a PD project. From this analysis, we identify central attributes of, and challenges...... to, PD walks. Walking with people in the context of design is a natural activity for the participatory designer, who acknowledges the importance of immersion and relationships in design. However, the various intentions of walking approaches indicate an underacknowledged awareness of walking methods....... With this study, we take a step towards a methodological framework for "design with the feet" in PD....

  16. Calcaneal loading during walking and running

    Science.gov (United States)

    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.

  17. Levy Walks Suboptimal under Predation Risk.

    Directory of Open Access Journals (Sweden)

    Masato S Abe

    2015-11-01

    Full Text Available 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.

  18. Coined quantum walks on percolation graphs

    Energy Technology Data Exchange (ETDEWEB)

    Leung, Godfrey; Knott, Paul; Bailey, Joe; Kendon, Viv, E-mail: V.Kendon@leeds.ac.uk [School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT (United Kingdom)

    2010-12-15

    Quantum walks, both discrete (coined) and continuous time, form the basis of several quantum algorithms and have been used to model processes such as transport in spin chains and quantum chemistry. The enhanced spreading and mixing properties of quantum walks compared with their classical counterparts have been well studied on regular structures and also shown to be sensitive to defects and imperfections in the lattice. As a simple example of a disordered system, we consider percolation lattices, in which edges or sites are randomly missing, interrupting the progress of the quantum walk. We use numerical simulation to study the properties of coined quantum walks on these percolation lattices in one and two dimensions. In one dimension (the line), we introduce a simple notion of quantum tunnelling and determine how this affects the properties of the quantum walk as it spreads. On two-dimensional percolation lattices, we show how the spreading rate varies from linear in the number of steps down to zero as the percolation probability decreases towards the critical point. This provides an example of fractional scaling in quantum-walk dynamics.

  19. Winding angles of long lattice walks

    Science.gov (United States)

    Hammer, Yosi; Kantor, Yacov

    2016-07-01

    We study the winding angles of random and self-avoiding walks (SAWs) on square and cubic lattices with number of steps N ranging up to 107. We show that the mean square winding angle of random walks converges to the theoretical form when N → ∞. For self-avoiding walks on the square lattice, we show that the ratio /2 converges slowly to the Gaussian value 3. For self-avoiding walks on the cubic lattice, we find that the ratio /2 exhibits non-monotonic dependence on N and reaches a maximum of 3.73(1) for N ≈ 104. We show that to a good approximation, the square winding angle of a self-avoiding walk on the cubic lattice can be obtained from the summation of the square change in the winding angles of lnN independent segments of the walk, where the ith segment contains 2i steps. We find that the square winding angle of the ith segment increases approximately as i0.5, which leads to an increase of the total square winding angle proportional to (lnN)1.5.

  20. Exploring scalar quantum walks on Cayley graphs

    CERN Document Server

    Acevedo, O L; Roland, J; Acevedo, Olga Lopez; Cerf, Nicolas J.

    2006-01-01

    A quantum walk, \\emph{i.e.}, the quantum evolution of a particle on a graph, is termed \\emph{scalar} if the internal space of the moving particle (often called the coin) has a dimension one. Here, we study the existence of scalar quantum walks on Cayley graphs, which are built from the generators of a group. After deriving a necessary condition on these generators for the existence of a scalar quantum walk, we present a general method to express the evolution operator of the walk, assuming homogeneity of the evolution. We use this necessary condition and the subsequent constructive method to investigate the existence of scalar quantum walks on Cayley graphs of various groups presented with two or three generators. In this restricted framework, we classify all groups -- in terms of relations between their generators -- that admit scalar quantum walks, and we also derive the form of the most general evolution operator. Finally, we point out some interesting special cases, and extend our study to a few examples ...

  1. Dynamic stability of quadruped robot walking on slope with trot gait

    Institute of Scientific and Technical Information of China (English)

    雷静桃

    2016-01-01

    The dynamic stability of a quadruped robot trotting on slope was analyzed.Compared with crawl gait, trot gait can improve walking speed of quadruped robots.When a quadruped robot trots, each leg is in the alternate state of swing phase or supporting phase, and two legs in the diagonal line are in the same phase.The feet in the supporting phase form a supporting region on the ground.When a quadruped robot walks on slope, the vertical distance from zero moment point ( ZMP) to the sup-porting diagonal line is defined as ZMP offset distance.Whether this distance is less than the maxi-mum offset distance or not, the stability of robot trotting on slope can be judged.The foot trajectory was planned with the sinusoidal function.Based on the kinematic analysis, the ZMP offset distance of quadruped robot under different slope angles, step length and step height was calculated, then the reasonable slope angle, step length and step height for quadruped robot trotting on slope to keep dy-namic stability can be determined.On the other hand, the posture angle of quadruped robot should be controlled within the desired range.Computer simulations were executed to verify the theoretical analysis.The study will provide reference for determining reasonable step parameters of the quadru-ped robot.

  2. Fuzzy clustering with Minkowski distance

    NARCIS (Netherlands)

    P.J.F. Groenen (Patrick); U. Kaymak (Uzay); J.M. van Rosmalen (Joost)

    2006-01-01

    textabstractDistances in the well known fuzzy c-means algorithm of Bezdek (1973) are measured by the squared Euclidean distance. Other distances have been used as well in fuzzy clustering. For example, Jajuga (1991) proposed to use the L_1-distance and Bobrowski and Bezdek (1991) also used the L_inf

  3. The sound of distance.

    Science.gov (United States)

    Rabaglia, Cristina D; Maglio, Sam J; Krehm, Madelaine; Seok, Jin H; Trope, Yaacov

    2016-07-01

    Human languages may be more than completely arbitrary symbolic systems. A growing literature supports sound symbolism, or the existence of consistent, intuitive relationships between speech sounds and specific concepts. Prior work establishes that these sound-to-meaning mappings can shape language-related judgments and decisions, but do their effects generalize beyond merely the linguistic and truly color how we navigate our environment? We examine this possibility, relating a predominant sound symbolic distinction (vowel frontness) to a novel associate (spatial proximity) in five studies. We show that changing one vowel in a label can influence estimations of distance, impacting judgment, perception, and action. The results (1) provide the first experimental support for a relationship between vowels and spatial distance and (2) demonstrate that sound-to-meaning mappings have outcomes that extend beyond just language and can - through a single sound - influence how we perceive and behave toward objects in the world. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Tolman's Luminosity-Distance, Poincare's Light-Distance and Cayley-Klein's Hyperbolic Distance

    CERN Document Server

    Pierseaux, Yves

    2009-01-01

    We deduce Tolman's formula of luminosity-distance in Cosmology from Poincare's definition of light-distance with Lorentz Transformation (LT).In Minkowskian metric, if distance is proper time (as it is often argued) then light-distance must be also the shortest distance, like proper duration (unlike Einstein's longest length within rest system). By introducing Poincare's proper light-distance in Einstein's basic synchronization we deduce a dilated distance between observer and receding mirror (with relativistic Doppler factor). Such a distance corresponds not to an Euclidean distance (Einstein's rigid rod) but to an Hyperbolic distance (Cayley-Klein) with a Lobatchevskian Horizon. From a basic proportionality hyperbolic distance-velocity, we deduce the law of Hubble. By following Penrose's Lobatchevskian representation of LT, we transform Special Relativity (SR) into an Hyperbolic Cosmological Relativity (HCR). by using only the LT but the whole LT. In Hyperbolic Rotation motion (basic active LT or Einstein's ...

  5. Distance, Borders, and Time

    DEFF Research Database (Denmark)

    Skillicorn, David; Walther, Olivier; Zheng, Quan

    is a combination of the physical geography of the target environment, and the mental and physical cost of following a seemingly random pattern of attacks. Focusing on the distance and time between attacks and taking into consideration the transaction costs that state boundaries impose, we wish to understand what......” of North and West Africa that depicts the permeability to violence. A better understanding of how location, time, and borders condition attacks enables planning, prepositioning, and response....

  6. Walking in postpoliomyelitis syndrome: The relationships between time-scored tests, walking in daily life and perceived mobility problems

    NARCIS (Netherlands)

    H.L.D. Horemans (Herwin); J.B.J. Bussmann (Hans); A. Beelen (Anita); H.J. Stam (Henk); F. Nollet (Frans)

    2005-01-01

    textabstractObjective: To compare walking test results with walking in daily life, and to investigate the relationships between walking tests, walking activity in daily life, and perceived mobility problems in patients with post-poliomyelitis syndrome. Subjects: Twenty-four ambulant patients with po

  7. Angular momentum in human walking.

    Science.gov (United States)

    Herr, Hugh; Popovic, Marko

    2008-02-01

    Angular momentum is a conserved physical quantity for isolated systems where no external moments act about a body's center of mass (CM). However, in the case of legged locomotion, where the body interacts with the environment (ground reaction forces), there is no a priori reason for this relationship to hold. A key hypothesis in this paper is that angular momentum is highly regulated throughout the walking cycle about all three spatial directions [|Lt| approximately 0], and therefore horizontal ground reaction forces and the center of pressure trajectory can be explained predominantly through an analysis that assumes zero net moment about the body's CM. Using a 16-segment human model and gait data for 10 study participants, we found that calculated zero-moment forces closely match experimental values (Rx2=0.91; Ry2=0.90). Additionally, the centroidal moment pivot (point where a line parallel to the ground reaction force, passing through the CM, intersects the ground) never leaves the ground support base, highlighting how closely the body regulates angular momentum. Principal component analysis was used to examine segmental contributions to whole-body angular momentum. We found that whole-body angular momentum is small, despite substantial segmental momenta, indicating large segment-to-segment cancellations ( approximately 95% medio-lateral, approximately 70% anterior-posterior and approximately 80% vertical). Specifically, we show that adjacent leg-segment momenta are balanced in the medio-lateral direction (left foot momentum cancels right foot momentum, etc.). Further, pelvis and abdomen momenta are balanced by leg, chest and head momenta in the anterior-posterior direction, and leg momentum is balanced by upper-body momentum in the vertical direction. Finally, we discuss the determinants of gait in the context of these segment-to-segment cancellations of angular momentum.

  8. Monge Distance between Quantum States

    CERN Document Server

    Zyczkowski, K; Zyczkowski, Karol; Slomczynski, Wojciech

    1998-01-01

    We define a metric in the space of quantum states taking the Monge distance between corresponding Husimi distributions (Q--functions). This quantity fulfills the axioms of a metric and satisfies the following semiclassical property: the distance between two coherent states is equal to the Euclidean distance between corresponding points in the classical phase space. We compute analytically distances between certain states (coherent, squeezed, Fock and thermal) and discuss a scheme for numerical computation of Monge distance for two arbitrary quantum states.

  9. Modulation of walking speed by changing optic flow in persons with stroke

    Directory of Open Access Journals (Sweden)

    Lamontagne Anouk

    2007-06-01

    Full Text Available Abstract Background Walking speed, which is often reduced after stroke, can be influenced by the perception of optic flow (OF speed. The present study aims to: 1 compare the modulation of walking speed in response to OF speed changes between persons with stroke and healthy controls and 2 investigate whether virtual environments (VE manipulating OF speed can be used to promote volitional changes in walking speed post stroke. Methods Twelve persons with stroke and 12 healthy individuals walked on a self-paced treadmill while viewing a virtual corridor in a helmet-mounted display. Two experiments were carried out on the same day. In experiment 1, the speed of an expanding OF was varied sinusoidally at 0.017 Hz (sine duration = 60 s, from 0 to 2 times the subject's comfortable walking speed, for a total duration of 5 minutes. In experiment 2, subjects were exposed to expanding OFs at discrete speeds that ranged from 0.25 to 2 times their comfortable speed. Each test trial was paired with a control trial performed at comfortable speed with matching OF. For each of the test trials, subjects were instructed to walk the distance within the same time as during the immediately preceding control trial. VEs were controlled by the CAREN-2 system (Motek. Instantaneous changes in gait speed (experiment 1 and the ratio of speed changes in the test trial over the control trial (experiment 2 were contrasted between the two groups of subjects. Results When OF speed was changing continuously (experiment 1, an out-of-phase modulation was observed in the gait speed of healthy subjects, such that slower OFs induced faster walking speeds, and vice versa. Persons with stroke displayed weaker (p 0.05, T-test. Conclusion Stroke affects the modulation of gait speed in response to changes in the perception of movement through different OF speeds. Nevertheless, the preservation of even a modest modulation enabled the persons with stroke to increase walking speed when

  10. Gait analysis in chronic heart failure: The calf as a locus of impaired walking capacity.

    Science.gov (United States)

    Panizzolo, Fausto A; Maiorana, Andrew J; Naylor, Louise H; Dembo, Lawrence; Lloyd, David G; Green, Daniel J; Rubenson, Jonas

    2014-11-28

    Reduced walking capacity, a hallmark of chronic heart failure (CHF), is strongly correlated with hospitalization and morbidity. The aim of this work was to perform a detailed biomechanical gait analysis to better identify mechanisms underlying reduced walking capacity in CHF. Inverse dynamic analyses were conducted in CHF patients and age- and exercise level-matched control subjects on an instrumented treadmill at self-selected treadmill walking speeds and at speeds representing +20% and -20% of the subjects' preferred speed. Surprisingly, no difference in preferred speed was observed between groups, possibly explained by an optimization of the mechanical cost of transport in both groups (the mechanical cost to travel a given distance; J/kg/m). The majority of limb kinematics and kinetics were also similar between groups, with the exception of greater ankle dorsiflexion angles during stance in CHF. Nevertheless, over two times greater ankle plantarflexion work during stance and per distance traveled is required for a given triceps surae muscle volume in CHF patients. This, together with a greater reliance on the ankle compared to the hip to power walking in CHF patients, especially at faster speeds, may contribute to the earlier onset of fatigue in CHF patients. This observation also helps explain the high correlation between triceps surae muscle volume and exercise capacity that has previously been reported in CHF. Considering the key role played by the plantarflexors in powering walking and their association with exercise capacity, our findings strongly suggest that exercise-based rehabilitation in CHF should not omit the ankle muscle group.

  11. Evaluating effects of method of administration on Walking Impairment Questionnaire.

    Science.gov (United States)

    Coyne, Karin S; Margolis, Mary Kay; Gilchrist, Kim A; Grandy, Susan P; Hiatt, William R; Ratchford, Andrea; Revicki, Dennis A; Weintraub, William S; Regensteiner, Judith G

    2003-08-01

    Intermittent claudication resulting from peripheral arterial disease (PAD) can substantially impair walking function. The Walking Impairment Questionnaire (WIQ) assesses patient self-reported difficulty in walking. Currently this questionnaire is validated for interviewer administration only. Since this can be burdensome in a large clinical trial, we examined the effects of alternative methods of administration on patient responses on the WIQ. The WIQ, which consists of four subscales (pain severity, distance, speed, stairs), was modified to be self-administered or interviewer-administered by telephone. Patients with PAD were recruited from two sites and randomized into two groups: in group 1 the WIQ was self-administered, then telephone-administered; in group 2 the WIQ was telephone-administered, then self-administered. The two administrations occurred 4 to 7 days apart. Additional measures (SF-36, EQ-5D, and PAD symptom scale) and clinical data were included to further assess the validity of the WIQ and symptoms in patients with claudication. Telephone interviews were conducted by trained interviewers using standardized scripts. Two-week test-retest reliability was assessed for both the self-administered WIQ (group 1) and the telephone-administered WIQ (group 2). Sixty patients were recruited at two sites (n = 30 per group). Seventy-eight percent were men; mean patient age was 67.1 years; and 83% of patients were white. Mean duration of PAD symptoms was 6.8 years. No significant differences were observed in WIQ subscale scores between self administration and telephone administration. No interaction effects between order and method of administration were detected. Cronbach alpha for distance, speed, and stair-climbing subscales ranged from 0.82 to 0.94. Correlations among WIQ subscales and the symptom scale were good (r = -0.34 to -0.57). Correlations of WIQ subscales with physical health subscales of the SF-36 (r = 0.24-0.59) were higher than for mental health

  12. Ultrasound monitoring of inter-knee distances during gait.

    Science.gov (United States)

    Lai, Daniel T H; Wrigley, Tim V; Palaniswami, M

    2009-01-01

    Knee osteoarthritis is an extremely common, debilitating disease associated with pain and loss of function. There is considerable interest in monitoring lower limb alignment due to its close association with joint overload leading to disease progression. The effects of gait modifications that can lower joint loading are of particular interest. Here we describe an ultrasound-based system for monitoring an important aspect of dynamic lower limb alignment, the inter-knee distance during walking. Monitoring this gait parameter should facilitate studies in reducing knee loading, a primary risk factor of knee osteoarthritis progression. The portable device is composed of an ultrasound sensor connected to an Intel iMote2 equipped with Bluetooth wireless capability. Static tests and calibration results show that the sensor possesses an effective beam envelope of 120 degrees, with maximum distance errors of 10% at the envelope edges. Dynamic walking trials reveal close correlation of inter-knee distance trends between that measured by an optical system (Optotrak Certus NDI) and the sensor device. The maximum average root mean square error was found to be 1.46 cm. Future work will focus on improving the accuracy of the device.

  13. Assessing walking behaviors of selected subpopulations.

    Science.gov (United States)

    Le Masurier, Guy C; Bauman, Adrian E; Corbin, Charles B; Konopack, James F; Umstattd, Renee M; VAN Emmerik, Richard E A

    2008-07-01

    Recent innovations in physical activity (PA) assessment have made it possible to assess the walking behaviors of a wide variety of populations. Objective measurement methods (e.g., pedometers, accelerometers) have been widely used to assess walking and other prevalent types of PA. Questionnaires suitable for international populations (e.g., the International Physical Activity Questionnaire and the Global Physical Activity Questionnaire) and measurement techniques for the assessment of gait patterns in disabled populations allow for the study of walking and its health benefits among many populations. Results of studies using the aforementioned techniques indicate that children are more active than adolescents and adolescents are more active than adults. Males, particularly young males, are typically more active than females. The benefits associated with regular participation in PA for youth and walking for older adults have been well documented, although improvements in the assessments of physical, cognitive, and psychosocial parameters must be made if we are to fully understand the benefits of walking for people of all ages. Most youth meet appropriate age-related PA activity recommendations, but adults, particularly older adults and adults with disabilities, are less likely to meet PA levels necessary for the accrual of health benefits. International studies indicate variation in walking by culture. It is clear, however, that walking is a prevalent form of PA across countries and a movement form that has great potential in global PA promotion. Continued development of measurement techniques that allow for the study of individualized gait patterns will help us add to the already rich body of knowledge on chronically disabled populations and allow for individual prescriptions for these populations.

  14. Kinematic evaluation of virtual walking trajectories.

    Science.gov (United States)

    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.

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

    NARCIS (Netherlands)

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

    2009-01-01

    Like human walking, passive dynamic walking—i.e. walking down a slope with no actuation except gravity—is energy efficient by exploiting the natural dynamics. In the animal world, neural oscillators termed central pattern generators (CPGs) provide the basic rhythm for muscular activity in

  16. The associated random walk and martingales in random walks with stationary increments

    CERN Document Server

    Grey, D R

    2010-01-01

    We extend the notion of the associated random walk and the Wald martingale in random walks where the increments are independent and identically distributed to the more general case of stationary ergodic increments. Examples are given where the increments are Markovian or Gaussian, and an application in queueing is considered.

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

    NARCIS (Netherlands)

    Buurke, Jaap; Hermens, Hermanus J.; Erren-Wolters, C.V.; Nene, A.V.

    2005-01-01

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

  18. Walking and child pedestrian injury: a systematic review of built environment correlates of safe walking.

    Science.gov (United States)

    Rothman, Linda; Buliung, Ron; Macarthur, Colin; To, Teresa; Howard, Andrew

    2014-02-01

    The child active transportation literature has focused on walking, with little attention to risk associated with increased traffic exposure. This paper reviews the literature related to built environment correlates of walking and pedestrian injury in children together, to broaden the current conceptualization of walkability to include injury prevention. Two independent searches were conducted focused on walking in children and child pedestrian injury within nine electronic databases until March, 2012. Studies were included which: 1) were quantitative 2) set in motorized countries 3) were either urban or suburban 4) investigated specific built environment risk factors 5) had outcomes of either walking in children and/or child pedestrian roadway collisions (ages 0-12). Built environment features were categorized according to those related to density, land use diversity or roadway design. Results were cross-tabulated to identify how built environment features associate with walking and injury. Fifty walking and 35 child pedestrian injury studies were identified. Only traffic calming and presence of playgrounds/recreation areas were consistently associated with more walking and less pedestrian injury. Several built environment features were associated with more walking, but with increased injury. Many features had inconsistent results or had not been investigated for either outcome. The findings emphasise the importance of incorporating safety into the conversation about creating more walkable cities.

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

    NARCIS (Netherlands)

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

    2009-01-01

    Like human walking, passive dynamic walking—i.e. walking down a slope with no actuation except gravity—is energy efficient by exploiting the natural dynamics. In the animal world, neural oscillators termed central pattern generators (CPGs) provide the basic rhythm for muscular activity in locomotion

  20. Incremental shuttle walk test in the assessment of patients with obstructive sleep apnea-hypopnea syndrome.

    Science.gov (United States)

    Billings, Catherine G; Aung, Thida; Renshaw, Stephen A; Bianchi, Stephen M

    2013-08-01

    Obstructive sleep apnea-hypopnea syndrome is associated independently with an increase in cardiovascular risk factors and is associated with self-reported lack of exercise. We aimed to investigate the utility of the incremental shuttle walk test in routine clinical practice to monitor physical capacity of patients with obstructive sleep apnea-hypopnea syndrome and explore whether continuous positive airway pressure therapy alters exercise capacity. Participants with symptomatic moderate/severe obstructive sleep apnea-hypopnea syndrome attending for a trial of continuous positive airway pressure therapy completed questionnaires assessing sleepiness and physical activity and underwent an incremental shuttle walk test. Subjects compliant or partially compliant with continuous positive airway pressure therapy underwent reassessment at 2 weeks, 3 months and 6 months post-initiation of therapy. Participants unable to tolerate continuous positive airway pressure therapy completed a single reassessment 6 months after their initial visit. Continuous positive airway pressure therapy resulted in an increased distance walked during the incremental shuttle walk test. Improvements in cardiovascular responses to exercise were identified. Compliant patients reported increased daily activity. The incremental shuttle walk test is a simple, reproducible and safe test that is responsive to continuous positive airway pressure treatment. Our findings support the use of the incremental shuttle walk test for monitoring the effects of continuous positive airway pressure treatment and may suggest its use in rehabilitation programmes designed to reduce obesity and cardiovascular risk factors in patients with obstructive sleep apnea-hypopnea syndrome. © 2013 European Sleep Research Society.

  1. Physical activity, functional capacity, and step variability during walking in people with lower-limb amputation.

    Science.gov (United States)

    Lin, Suh-Jen; Winston, Katie D; Mitchell, Jill; Girlinghouse, Jacob; Crochet, Karleigh

    2014-01-01

    Physical activity is important for general health. For an individual with amputation to sustain physical activity, certain functional capacity might be needed. Gait variability is related to the incidence of falls. This study explored the relationship between physical activity and a few common performance measures (six-minute walk test, step length variability, step width variability, and comfortable walking speed) in individuals with unilateral lower-limb amputation. Twenty individuals completed the study (age: 50±11yrs). Twelve of them had transtibial amputation, seven had transfemoral amputation, and one had through-knee amputation. Gait data was collected by the GaitRite instrumented walkway while participants performed a 3-min comfortable walking trial followed by a six-minute walk test. Physical activity was indicated by the mean of 7-day step counts via a pedometer. Gait variability was calculated by the coefficient of variation. Pearson correlation analysis was conducted between physical activity level and the 4 performance measures. Significance level was set at 0.05. Physical activity correlates strongly to comfortable walking speed (r=0.76), six-minute walk distance (r=0.67), and correlates fairly to step width variability (r=0.44). On the contrary, physical activity is inversely related to step length variability of the prosthetic leg (r=-0.46) and of the sound leg (r=-0.47). Having better functional capacity and lateral stability might enable an individual with lower-limb amputation to engage in a higher physical activity level, or vise versa. However, our conclusions are only preliminary as limited by the small sample size.

  2. Walking economy during cued versus non-cued self-selected treadmill walking in persons with Parkinson's disease.

    Science.gov (United States)

    Gallo, Paul M; McIsaac, Tara L; Garber, Carol Ewing

    2014-01-01

    Gait impairments related to Parkinson's disease (PD) include variable step length and decreased walking velocity, which may result in poorer walking economy. Auditory cueing is a common method used to improve gait mechanics in PD that has been shown to worsen walking economy at set treadmill walking speeds. It is unknown if auditory cueing has the same effects on walking economy at self-selected treadmill walking speeds. To determine if auditory cueing will affect walking economy at self-selected treadmill walking speeds and at speeds slightly faster and slower than self-selected. Twenty-two participants with moderate PD performed three, 6-minute bouts of treadmill walking at three speeds (self-selected and ± 0.22 m·sec-1). One session used cueing and the other without cueing. Energy expenditure was measured and walking economy was calculated (energy expenditure/power). Poorer walking economy and higher energy expenditure occurred during cued walking at a self-selected and a slightly faster walking speed, but there was no apparent difference at the slightly slower speed. These results suggest that potential gait benefits of auditory cueing may come at an energy cost and poorer walking economy for persons with PD at least at some treadmill walking speeds.

  3. The DDO IVC Distance Project

    CERN Document Server

    Gladders, M D; Burns, C R; Attard, A; Casey, M P; Hamilton, D; Mallén-Ornelas, G; Karr, J L; Poirier, S M; Sawicki, M; Barrientos, F; Barkhouse, W A; Brodwin, M; Clark, J; McNaughton, R; Ruetalo-Pacheco, M; Mochnacki, S W; Gladders, Michael D.; Clarke, Tracy E.; Burns, Christopher R.; Attard, Allen; Casey, Michael P.; Hamilton, Devon; Mallen-Ornelas, Gabriela; Karr, Jennifer L.; Poirier, Sara M.; Sawicki, Marcin; Barrientos, Felipe; Barkhouse, Wayne; Brodwin, Mark; Clark, Jason; Naughton, Rosemary Mc; Ruetalo-Pacheco, Marcelo; Mochnacki, Stefan W.

    1998-01-01

    We present the first set of distance limits from the David Dunlap Observatory Intermediate Velocity Cloud (DDO IVC) distance project. Such distance measures are crucial to understanding the origins and dynamics of IVCs, as the distances set most of the basic physical parameters for the clouds. Currently there are very few IVCs with reliably known distances. This paper describes in some detail the basic techniques used to measure distances, with particular emphasis on the the analysis of interstellar absorption line data, which forms the basis of our distance determinations. As an example, we provide a detailed description of our distance determination for the Draco Cloud. Preliminary distance limits for a total of eleven clouds are provided.

  4. Advanced hierarchical distance sampling

    Science.gov (United States)

    Royle, Andy

    2016-01-01

    In this chapter, we cover a number of important extensions of the basic hierarchical distance-sampling (HDS) framework from Chapter 8. First, we discuss the inclusion of “individual covariates,” such as group size, in the HDS model. This is important in many surveys where animals form natural groups that are the primary observation unit, with the size of the group expected to have some influence on detectability. We also discuss HDS integrated with time-removal and double-observer or capture-recapture sampling. These “combined protocols” can be formulated as HDS models with individual covariates, and thus they have a commonality with HDS models involving group structure (group size being just another individual covariate). We cover several varieties of open-population HDS models that accommodate population dynamics. On one end of the spectrum, we cover models that allow replicate distance sampling surveys within a year, which estimate abundance relative to availability and temporary emigration through time. We consider a robust design version of that model. We then consider models with explicit dynamics based on the Dail and Madsen (2011) model and the work of Sollmann et al. (2015). The final major theme of this chapter is relatively newly developed spatial distance sampling models that accommodate explicit models describing the spatial distribution of individuals known as Point Process models. We provide novel formulations of spatial DS and HDS models in this chapter, including implementations of those models in the unmarked package using a hack of the pcount function for N-mixture models.

  5. Distance Metric Tracking

    Science.gov (United States)

    2016-03-02

    520, 2004. 16 [12] E.C. Hall and R.M. Willett. Online convex optimization in dynamic environ- ments. Selected Topics in Signal Processing, IEEE Journal...Conference on Machine Learning, pages 1160–1167. ACM, 2008. [25] Eric P Xing, Michael I Jordan, Stuart Russell, and Andrew Y Ng. Distance metric...whereBψ is any Bregman divergence and ηt is the learning rate parameter. From ( Hall & Willett, 2015) we have: Theorem 1. G` = max θ∈Θ,`∈L ‖∇f(θ)‖ φmax = 1

  6. Long distance tunneling

    CERN Document Server

    Ivlev, B I

    2005-01-01

    Quantum tunneling between two potential wells in a magnetic field can be strongly increased when the potential barrier varies in the direction perpendicular to the line connecting the two wells and remains constant along this line. A periodic structure of the wave function is formed in the direction joining the wells. The resulting motion can be coherent like motion in a conventional narrow band periodic structure. A particle penetrates the barrier over a long distance which strongly contrasts to WKB-like tunneling. The whole problem is stationary. The coherent process can be influenced by dissipation.

  7. Distances on Lozenge Tilings

    CERN Document Server

    Bodini, Olivier; Fernique, Thomas

    2009-01-01

    In this paper, a structural property of the set of lozenge tilings of a 2n-gon is highlighted. We introduce a simple combinatorial value called Hamming-distance, which is a lower bound for the flipdistance (i.e. the number of necessary local transformations involving three lozenges) between two given tilings. It is here proven that, for n5, We show that there is some deficient pairs of tilings for which the flip connection needs more flips than the combinatorial lower bound indicates.

  8. Distance Teaching on Bornholm

    DEFF Research Database (Denmark)

    Hansen, Finn J. S.; Clausen, Christian

    2001-01-01

    and the organisational set-up. It is debated which kind of social learning that has taken place. The innovation process was based on the implementation of an inflexible video-conference system without any proactive considerations of organisational change or pedagocical development. User appropriation of the technology......The case study represents an example of a top-down introduction of distance teaching as part of Danish trials with the introduction of multimedia in education. The study is concerned with the background, aim and context of the trial as well as the role and working of the technology...

  9. Feasibility of Serial 6-min Walk Tests in Patients with Acute Heart Failure.

    Science.gov (United States)

    Collins, Sean P; Thorn, Michael; Nowak, Richard M; Levy, Phillip D; Fermann, Gregory J; Hiestand, Brian C; Cowart, Tillman Douglas; Venuti, Robert P; Hiatt, William R; Foo, ShiYin; Pang, Peter S

    2017-09-11

    Functional status assessment is common in many cardiovascular diseases but it has undergone limited study in the setting of acute heart failure (AHF). Accordingly, we performed a pilot study of the feasibility of the six-minute walk test (6MWT) at the emergency department (ED) presentation and through the hospitalization in patients with AHF. From November 2014 to February 2015, we conducted a multicenter, observational study of ED patients, aged 18-85 years, whose primary ED admission diagnosis was AHF. Other criteria for enrollment included a left ventricular ejection fraction ≤40%, systolic blood pressure between 90 and 170 mmHg, and verbal confirmation that the patient was able to walk >30 m at the baseline, prior to ED presentation. Study teams were uniformly trained to administer a 6MWT. Patients underwent a baseline 6MWT within 24 h of ED presentation (Day 1) and follow-up 6MWTs at 24 (Day 2), 48 (Day 3), and 120 h (Day 5). A total of 46 patients (65.2% male, 73.9% African American) had a day one mean walk distance of 137.3 ± 78 m, day 2 of 170.9 ± 100 m, and day 3 of 180.8 ± 98 m. The 6MWT demonstrated good reproducibility, as the distance walked on the first 6MWT on Day 3 was similar to the distance on the repeated 6MWT the same day. Our pilot study demonstrates the feasibility of the 6MWT as a functional status endpoint in AHF patients. A larger study in a more demographically diverse cohort of patients is necessary to confirm its utility and association with 30-day heart failure (HF) events.

  10. Protocol Variations and Six-Minute Walk Test Performance in Stroke Survivors: A Systematic Review with Meta-Analysis

    Science.gov (United States)

    Dunn, A.; Marsden, D. L.; Nugent, E.; Van Vliet, P.; Spratt, N. J.; Attia, J.; Callister, R.

    2015-01-01

    Objective. To investigate the use of the six-minute walk test (6MWT) for stroke survivors, including adherence to 6MWT protocol guidelines and distances achieved. Methods. A systematic search was conducted from inception to March 2014. Included studies reported a baseline (intervention studies) or first instance (observational studies) measure for the 6MWT performed by stroke survivors regardless of time after stroke.  Results. Of 127 studies (participants n = 6,012) that met the inclusion criteria, 64 were also suitable for meta-analysis. Only 25 studies made reference to the American Thoracic Society (ATS) standards for the 6MWT, and 28 reported using the protocol standard 30 m walkway. Thirty-nine studies modified the protocol walkway, while 60 studies did not specify the walkway used. On average, stroke survivors walked 284 ± 107 m during the 6MWT, which is substantially less than healthy age-matched individuals. The meta-analysis identified that changes to the ATS protocol walkway are associated with reductions in walking distances achieved. Conclusion. The 6MWT is now widely used in stroke studies. The distances achieved by stroke patients indicate substantially compromised walking ability. Variations to the standard 30 m walkway for the 6MWT are common and caution should be used when comparing the values achieved from studies using different walkway lengths. PMID:25685596

  11. Protocol Variations and Six-Minute Walk Test Performance in Stroke Survivors: A Systematic Review with Meta-Analysis

    Directory of Open Access Journals (Sweden)

    A. Dunn

    2015-01-01

    Full Text Available Objective. To investigate the use of the six-minute walk test (6MWT for stroke survivors, including adherence to 6MWT protocol guidelines and distances achieved. Methods. A systematic search was conducted from inception to March 2014. Included studies reported a baseline (intervention studies or first instance (observational studies measure for the 6MWT performed by stroke survivors regardless of time after stroke.  Results. Of 127 studies (participants n = 6,012 that met the inclusion criteria, 64 were also suitable for meta-analysis. Only 25 studies made reference to the American Thoracic Society (ATS standards for the 6MWT, and 28 reported using the protocol standard 30 m walkway. Thirty-nine studies modified the protocol walkway, while 60 studies did not specify the walkway used. On average, stroke survivors walked 284 ± 107 m during the 6MWT, which is substantially less than healthy age-matched individuals. The meta-analysis identified that changes to the ATS protocol walkway are associated with reductions in walking distances achieved. Conclusion. The 6MWT is now widely used in stroke studies. The distances achieved by stroke patients indicate substantially compromised walking ability. Variations to the standard 30 m walkway for the 6MWT are common and caution should be used when comparing the values achieved from studies using different walkway lengths.

  12. Distance Learning. Volume I: Distance Learning Analysis Study.

    Science.gov (United States)

    1998-09-01

    The primary focus of this project is the determination of the feasibility and cost effectiveness of applying Distance Learning strategies to 22...selected PPSCP courses and development of a Distance Learning Analysis Procedures Manual.

  13. PERBANDINGAN EUCLIDEAN DISTANCE DENGAN CANBERRA DISTANCE PADA FACE RECOGNITION

    Directory of Open Access Journals (Sweden)

    Sendhy Rachmat Wurdianarto

    2014-08-01

    Full Text Available Perkembangan ilmu pada dunia komputer sangatlah pesat. Salah satu yang menandai hal ini adalah ilmu komputer telah merambah pada dunia biometrik. Arti biometrik sendiri adalah karakter-karakter manusia yang dapat digunakan untuk membedakan antara orang yang satu dengan yang lainnya. Salah satu pemanfaatan karakter / organ tubuh pada setiap manusia yang digunakan untuk identifikasi (pengenalan adalah dengan memanfaatkan wajah. Dari permasalahan diatas dalam pengenalan lebih tentang aplikasi Matlab pada Face Recognation menggunakan metode Euclidean Distance dan Canberra Distance. Model pengembangan aplikasi yang digunakan adalah model waterfall. Model waterfall beriisi rangkaian aktivitas proses yang disajikan dalam proses analisa kebutuhan, desain menggunakan UML (Unified Modeling Language, inputan objek gambar diproses menggunakan Euclidean Distance dan Canberra Distance. Kesimpulan yang dapat ditarik adalah aplikasi face Recognation menggunakan metode euclidean Distance dan Canverra Distance terdapat kelebihan dan kekurangan masing-masing. Untuk kedepannya aplikasi tersebut dapat dikembangkan dengan menggunakan objek berupa video ataupun objek lainnya.   Kata kunci : Euclidean Distance, Face Recognition, Biometrik, Canberra Distance

  14. [A new procedure for the estimation of physical fitness of patients during clinical rehabilitation using the 6-minutes walk test].

    Science.gov (United States)

    Marek, W; Marek, E; Friz, Y; Vogel, P; Mückenhoff, K; Kotschy-Lang, N

    2010-03-01

    AIMS OF THE INVESTIGATION: The repetition of the 6-minutes walk test (6 MWT) in older patients is frequently performed in order to document the maximal walking distance, although it is not recommended in any guidelines on exercise tests and although there is common consent to save clinical resources in terms of time and staff. Therefore, we have examined whether and to what extent the repetition of the walk tests helps patients to get more familiar with this kind of exercise test. Thus the acquired physiological data should reliably describe the physical fitness of the patients at the beginning and at the end of their clinical rehabilitation. 35 patients performed their walk tests before and after 3 - 4 weeks of clinical rehabilitation. Each test has been repeated after one hour of recovery. The patients were instructed to walk during 6 minutes as fast as possible. They were equipped with a mobile pulse oximeter for recording oxygen saturation and heart rate. The distance, S, and the heart rate, fc, were measured. Measurements were performed every 30 seconds and recorded. The efficiency, E (E = S/6/fc), was calculated as the ratio of distance per minute and the mean heart rate during the test. In the first test the patients walked 416 +/- 63 m at a heart rate of 104.7 +/- 15.7 beats/min, in the first repeated test 454 +/- 71 m at a heart of 106.3 +/- 17.4 beats/min. In the second test, after clinical therapy, they walked 438 +/- 58 m at a heart rate of 106.3 +/- 17.4 beats/min, in the second repeated test 473 +/- 56 m at 108.6 +/- 13.2/min. The difference of the walking distances of the tests at the entrance were found to be 38.4 +/- 26.2 m (+ 9.3 +/- 6.2%), at the end of clinical rehabilitation 35 +/- 26 m (+ 8.4 +/- 6.4%). Both differences are found to be independent from the distance of the first test. They are not significantly different. The efficiency was not significantly different in the initial and final test (0.673 +/- 0.129 and 0.689 +/- 0.085 m

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

    Science.gov (United States)

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

    2012-04-01

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

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

    Science.gov (United States)

    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.

  17. Vection in depth during treadmill walking.

    Science.gov (United States)

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

    2013-01-01

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

  18. Myoelectric walking mode classification for transtibial amputees.

    Science.gov (United States)

    Miller, Jason D; Beazer, Mahyo Seyedali; Hahn, Michael E

    2013-10-01

    Myoelectric control algorithms have the potential to detect an amputee's motion intent and allow the prosthetic to adapt to changes in walking mode. The development of a myoelectric walking mode classifier for transtibial amputees is outlined. Myoelectric signals from four muscles (tibialis anterior, medial gastrocnemius (MG), vastus lateralis, and biceps femoris) were recorded for five nonamputee subjects and five transtibial amputees over a variety of walking modes: level ground at three speeds, ramp ascent/descent, and stair ascent/descent. These signals were decomposed into relevant features (mean absolute value, variance, wavelength, number of slope sign changes, number of zero crossings) over three subwindows from the gait cycle and used to test the ability of classification algorithms for transtibial amputees using linear discriminant analysis (LDA) and support vector machine (SVM) classifiers. Detection of all seven walking modes had an accuracy of 97.9% for the amputee group and 94.7% for the nonamputee group. Misclassifications occurred most frequently between different walking speeds due to the similar nature of the gait pattern. Stair ascent/descent had the best classification accuracy with 99.8% for the amputee group and 100.0% for the nonamputee group. Stability of the developed classifier was explored using an electrode shift disturbance for each muscle. Shifting the electrode placement of the MG had the most pronounced effect on the classification accuracy for both samples. No increase in classification accuracy was observed when using SVM compared to LDA for the current dataset.

  19. Coined quantum walks on percolation graphs

    CERN Document Server

    Leung, Godfrey; Bailey, Joe; Kendon, Viv

    2010-01-01

    Quantum walks, both discrete (coined) and continuous time, form the basis of several quantum algorithms and have been used to model processes such as transport in spin chains and quantum chemistry. The enhanced spreading and mixing properties of quantum walks compared with their classical counterparts have been well-studied on regular structures and also shown to be sensitive to defects and imperfections in the lattice. As a simple example of a disordered system, we consider percolation lattices, in which edges or sites are randomly missing, interrupting the progress of the quantum walk. We use numerical simulation to study the properties of coined quantum walks on these percolation lattices in one and two dimensions. In one dimension (the line) we introduce a simple notion of quantum tunneling and determine how this affects the properties of the quantum walk as it spreads. On two-dimensional percolation lattices, we show how the spreading rate varies from linear to square root in the number of steps, as the ...

  20. Association of waist circumference with impaired six-minute walk in type 2 diabetes mellitus is independent of cardiac function.

    Science.gov (United States)

    Wang, Ying; Yang, Hong; Nolan, Mark; Negishi, Kazuaki; Burgess, John; Marwick, Thomas H

    2016-04-01

    Subclinical left ventricular dysfunction has been associated with impaired exercise capacity in type 2 diabetes mellitus. In this community-based study of 274 asymptomatic T2DM patients (71±4 years, 55% men) with preserved ejection fraction, a comprehensive resting echocardiogram was performed to gather sensitive systolic and diastolic function parameters (including speckle tracking echocardiography), and a standard six-minute walk test was performed. Tertiles of increasing waist circumference were associated with worsening walk distance. In this community-based study, we found an association of waist circumference with impaired exercise capacity, independent of age, gender, diabetes duration, insulin and angiotensin blockade, LV mass, systolic and diastolic function.