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Sample records for 6-minute walking distance

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

    PubMed Central

    Rivera-Lebron, Belinda N.; Kreider, Maryl; Lee, James; Kawut, Steven M.

    2016-01-01

    Abstract 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 (P=0.02). For each 200-mL reduction in forced vital capacity, the walk distance decreased by 15.0 m (95% CI, 9.0–21.1; P<0.001). 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; P=0.006). 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. PMID:27076905

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

    PubMed

    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.

  3. Disability Affects the 6-Minute Walking Distance in Obese Subjects (BMI>40 kg/m2)

    PubMed Central

    Donini, Lorenzo Maria; Poggiogalle, Eleonora; Mosca, Veronica; Pinto, Alessandro; Brunani, Amelia; Capodaglio, Paolo

    2013-01-01

    Introduction In obese subjects, the relative reduction of the skeletal muscle strength, the reduced cardio-pulmonary capacity and tolerance to effort, the higher metabolic costs and, therefore, the increased inefficiency of gait together with the increased prevalence of co-morbid conditions might interfere with walking. Performance tests, such as the six-minute walking test (6MWT), can unveil the limitations in cardio-respiratory and motor functions underlying the obesity-related disability. Therefore the aims of the present study were: to explore the determinants of the 6-minute walking distance (6MWD) and to investigate the predictors of interruption of the walk test in obese subjects. Methods Obese patients [body mass index (BMI)>40 kg/m2] were recruited from January 2009 to December 2011. Anthropometry, body composition, specific questionnaire for Obesity-related Disabilities (TSD-OC test), fitness status and 6MWT data were evaluated. The correlation between the 6MWD and the potential independent variables (anthropometric parameters, body composition, muscle strength, flexibility and disability) were analysed. The variables which were singularly correlated with the response variable were included in a multivariated regression model. Finally, the correlation between nutritional and functional parameters and test interruption was investigated. Results 354 subjects (87 males, mean age 48.5±14 years, 267 females, mean age 49.8±15 years) were enrolled in the study. Age, weight, height, BMI, fat mass and fat free mass indexes, handgrip strength and disability were significantly correlated with the 6MWD and considered in the multivariate analysis. The determination coefficient of the regression analysis ranged from 0.21 to 0.47 for the different models. Body weight, BMI, waist circumference, TSD-OC test score and flexibility were found to be predictors of the 6MWT interruption. Discussion The present study demonstrated the impact of disability in obese subjects

  4. Minimal important difference of the 6-minute walk distance in lung cancer.

    PubMed

    Granger, Catherine L; Holland, Anne E; Gordon, Ian R; Denehy, Linda

    2015-05-01

    The 6-minute walk distance (6MWD) is one of the most commonly used measures of functional capacity in lung cancer, however, the minimal important difference (MID) has not been established. The aims of this exploratory study are, in lung cancer, to estimate (1) the MID of the 6MWD and (2) relationship between 6MWD, demographic and disease-related factors. Fifty-six participants with stage I-IV lung cancer completed the 6MWD prior to treatment and 10 weeks later. No exercise intervention occurred. Additional measures included European Organization for Research and Treatment of Cancer questionnaire (EORTC-QLQ-C30) and questionnaires assessing function, physical activity and symptoms. MID was calculated using anchor- and distribution-based methods. The mean 6MWD decline in participants classed as deteriorated was 60 m compared with 16 m in participants classed as not-deteriorated (p = 0.01). The receiver operating curve indicated a cut-off value for clinically relevant change to be 42 m (95% confidence interval (CI) 6-75) (area under curve = 0.66, 95% CI 0.51-0.81) or a 9.5% change. Distribution-based methods indicated an MID between 22 m (95% CI 18-26) and 32 m (95% CI 20-42). Higher 6MWD correlated with better function (r = -0.42, p = 0.001), physical activity (r = 0.56, p < 0.005) and dyspnoea (r = -0.44, p = 0.001). The MID for deterioration of the 6MWD in lung cancer is estimated to be between 22 m and 42 m or a change of 9.5%. PMID:25749346

  5. Individualized Prediction of Changes in 6-Minute Walk Distance for Patients with Duchenne Muscular Dystrophy

    PubMed Central

    Goemans, Nathalie; vanden Hauwe, Marleen; Signorovitch, James; Swallow, Elyse; Song, Jinlin

    2016-01-01

    Background Deficits in ambulatory function progress at heterogeneous rates among individuals with Duchenne muscular dystrophy (DMD). The resulting inherent variability in ambulatory outcomes has complicated the design of drug efficacy trials and clouded the interpretation of trial results. We developed a prediction model for 1-year change in the six minute walk distance (6MWD) among DMD patients, and compared its predictive value to that of commonly used prognostic factors (age, baseline 6MWD, and steroid use). Methods Natural history data were collected from DMD patients at routine follow up visits approximately every 6 months over the course of 2–5 years. Assessments included ambulatory function and steroid use. The annualized change in 6MWD (Δ6MWD) was studied between all pairs of visits separated by 8–16 months. Prediction models were developed using multivariable regression for repeated measures, and evaluated using cross-validation. Results Among n = 191 follow-up intervals (n = 39 boys), mean starting age was 9.4 years, mean starting 6MWD was 351.8 meters, and 75% had received steroids for at least one year. Over the subsequent 8–16 months, mean Δ6MWD was -37.0 meters with a standard deviation (SD) of 93.7 meters. Predictions based on a composite of age, baseline 6MWD, and steroid use explained 28% of variation in Δ6MWD (R2 = 0.28, residual SD = 79.4 meters). A broadened prognostic model, adding timed 10-meter walk/run, 4-stair climb, and rise from supine, as well as height and weight, significantly improved prediction, explaining 59% of variation in Δ6MWD after cross-validation (R2 = 0.59, residual SD = 59.7 meters). Conclusions A prognostic model incorporating timed function tests significantly improved prediction of 1-year changes in 6MWD. Explained variation was more than doubled compared to predictions based only on age, baseline 6MWD, and steroid use. There is significant potential for composite prognostic models to inform DMD clinical trials

  6. Sex and menopause differences in response to tadalafil: 6-minute walk distance and time to clinical worsening

    PubMed Central

    Rusiecki, Jennifer; Rao, Youlan; Cleveland, Jody; Rhinehart, Zachary; Champion, Hunter C.

    2015-01-01

    Abstract Pulmonary arterial hypertension (PAH) is a female-predominant disease, but there are little data on treatment response by sex and menopausal status. In this retrospective analysis of the Pulmonary Arterial Hypertension and Response to Tadalafil (PHIRST) randomized clinical trial, we assessed treatment response between the sexes by examining change in 6-minute walk distance (6MWD) and time to clinical worsening (TCW). We examined the effect of menopausal status on the same treatment measures. 6MWD was recorded before and after 16 weeks of treatment with tadalafil or placebo in the PHIRST study cohort of 340 subjects (264 females, 76 males). A univariate analysis was used to assess the effect of sex on change in 6MWD and TCW. Multivariate linear regression and Cox proportional hazards models were built for 6MWD and TCW, respectively. Women were subdivided by age as a surrogate for menopausal status. The linear trend test and the log-rank test were performed on change in 6MWD and TCW by age. For tadalafil-treated patients, a significant difference in change in 6MWD by sex (mean: 48.6 m for males vs. 34.7 m for females; P = 0.01) was found, but it was not significant in multivariate analysis (P = 0.08). There was a trend toward a female age-dependent effect in change in 6MWD; the premenopausal group showed the greatest improvement. A significant sex- or age-dependent effect on TCW was not present. In conclusion, this retrospective analysis of the PHIRST trial suggests that men and premenopausal women may experience greater functional improvement when treated with tadalafil than older women, but there was no consistent sex or menopausal effect on TCW. PMID:26697177

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

    PubMed Central

    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

  8. Reproducibility of the 6-minute walk test in obese adults.

    PubMed

    Beriault, K; Carpentier, A C; Gagnon, C; Ménard, J; Baillargeon, J-P; Ardilouze, J-L; Langlois, M-F

    2009-10-01

    The six-minute walk test (6MWT) is an inexpensive, quick and safe tool to evaluate the functional capacity of patients with heart failure and chronic obstructive pulmonary disease. The aim of this study was to determine the reproducibility of the 6MWT in overweight and obese individuals. We thus undertook a prospective repeated-measure validity study taking place in our academic weight management outpatient clinic. The 6MWT was conducted twice the same day in 21 overweight or obese adult subjects (15 females and 6 males). Repeatability of walking distance was the primary outcome. Anthropometric measures, blood pressure and heart rate were also recorded. Participant's mean BMI was 37.2+/-9.8 kg/m(2) (range: 27.0-62.3 kg/m(2)). Walking distance in the morning (mean=452+/-90 m) and in the afternoon (mean=458+/-97 m) were highly correlated (r=0.948; 95% Confidence Interval 0.877-0.978; p<0.001). Walking distance was negatively correlated with BMI (r=-0.47, p=0.03), waist circumference (r=-0.43, p=0.05) and pre-test heart rate (r=-0.54, p=0.01). Our findings indicate that the 6MWT is highly reproducible in obese subjects and could thus be used as a fitness indicator in clinical studies and clinical care in this population.

  9. Strong correlation between the 6-minute walk test and accelerometry functional outcomes in boys with Duchenne muscular dystrophy.

    PubMed

    Davidson, Zoe E; Ryan, Monique M; Kornberg, Andrew J; Walker, Karen Z; Truby, Helen

    2015-03-01

    Accelerometry provides information on habitual physical capability that may be of value in the assessment of function in Duchenne muscular dystrophy. This preliminary investigation describes the relationship between community ambulation measured by the StepWatch activity monitor and the current standard of functional assessment, the 6-minute walk test, in ambulatory boys with Duchenne muscular dystrophy (n = 16) and healthy controls (n = 13). All participants completed a 6-minute walk test and wore the StepWatch™ monitor for 5 consecutive days. Both the 6-minute walk test and StepWatch accelerometry identified a decreased capacity for ambulation in boys with Duchenne compared to healthy controls. There were strong, significant correlations between 6-minute walk distance and all StepWatch parameters in affected boys only (r = 0.701-0.804). These data proffer intriguing observations that warrant further exploration. Specifically, accelerometry outcomes may compliment the 6-minute walk test in assessment of therapeutic interventions for Duchenne muscular dystrophy.

  10. Decreased Variability of the 6-Minute Walk Test by Heart Rate Correction in Patients with Neuromuscular Disease

    PubMed Central

    Prahm, Kira P.; Witting, Nanna; Vissing, John

    2014-01-01

    Objective The 6-minute walk test is widely used to assess functional status in neurological disorders. However, the test is subject to great inter-test variability due to fluctuating motivation, fatigue and learning effects. We investigated whether inter-test variability of the 6MWT can be reduced by heart rate correction. Methods Sixteen patients with neuromuscular diseases, including Facioscapulohumeral muscular dystrophy, Limb-girdle muscular dystrophy, Charcot-Marie-Tooths, Dystrophia Myotonica and Congenital Myopathy and 12 healthy subjects were studied. Patients were excluded if they had cardiac arrhythmias, if they received drug treatment for hypertension or any other medical conditions that could interfere with the interpretation of the heart rate and walking capability. All completed three 6-minute walk tests on three different test-days. Heart rate was measured continuously. Results Successive standard 6-minute walk tests showed considerable learning effects between Tests 1 and 2 (4.9%; P = 0.026), and Tests 2 and 3 (4.5%; P = 0.020) in patients. The same was seen in controls between Tests 1 and 2 (8.1%; P = 0.039)). Heart rate correction abolished this learning effect. Conclusion A modified 6-minute walk test, by correcting walking distance with average heart rate during walking, decreases the variability among repeated 6-minute walk tests, and should be considered as an alternative outcome measure to the standard 6-minute walk test in future clinical follow-up and treatment trials. PMID:25479403

  11. Factors associated with the 6-minute walk test in nursing home residents and community-dwelling older adults

    PubMed Central

    Caballer, Vicent-Benavent; Lisón, Juan Francisco; Rosado-Calatayud, Pedro; Amer-Cuenca, Juan José; Segura-Orti, Eva

    2015-01-01

    [Purpose] The main objective of this study was to determine the contributions and extent to which certain physical measurements explain performance in the 6-minute walk test in healthy older adults living in a geriatric nursing home and for older adults dwelling in the community. [Subjects] The subjects were 122 adults aged 65 and older with no cognitive impairment who were independent in their daily activities. [Methods] The 6-minute walk test, age, body mass index, walking speed, chair stand test, Berg Balance Scale, Timed Up-and-Go test, rectus femoris cross-sectional area, Short Physical Performance Battery, and hand-grip strength were examined. [Results] Strong significant associations were found between mobility, lower-limb function, balance, and the 6-minute walk test. A stepwise multiple regression on the entire sample showed that lower-limb function was a significant and independent predictor for the 6-minute walk test. Additionally, lower-limb function was a strong predictor for the 6-minute walk test in our nursing home group, whereas mobility was found to be the best predictor in our community-dwelling group. [Conclusion] Better lower-limb function, balance, and mobility result in a higher distance covered by healthy older adults. Lower-limb function and mobility appeared to best determine walking performance in the nursing home and community-dwelling groups, respectively. PMID:26696740

  12. Predictors of 6-minute walk test results in lean, obese and morbidly obese women.

    PubMed

    Hulens, M; Vansant, G; Claessens, A L; Lysens, R; Muls, E

    2003-04-01

    The aim of this study was first, to assess the presence of medical conditions that might interfere with walking; second, to assess the differences in walking capacity, perceived exertion and physical complaints between lean, obese and morbidly obese women; and third, to identify anthropometric, physical fitness and physical activity variables that contribute to the variability in the distance achieved during a 6-minute walk test in lean and obese women. A total of 85 overweight and obese females (18-65 years, body mass index (BMI) > or = 27.5 kg m(-2)), 133 morbidly obese females (BMI > or = 35 kg m-2) and 82 age-matched sedentary lean female volunteers (BMI < or = 26 kg m(-2)) were recruited. Patients suffering from severe musculoskeletal and cardiopulmonary disease were excluded from the study. Prior to the test, conditions that might interfere with walking and hours of TV watching were asked for. Physical activity pattern was assessed using the Baecke questionnaire. Weight, height, body composition (bioelectrical impedance method), isokinetic concentric quadriceps strength (Cybex) and peak oxygen uptake (peakVO2_bicycle ergometer) were measured. A 6-minute walk test was performed and heart rate, walking distance, Borg rating scale of perceived exertion (RPE) and physical complaints at the end of the test were recorded. In obese and particularly in morbidly obese women suffering from skin friction, urinary stress incontinence, varicose veins, foot static problems and pain, wearing insoles, suffering from knee pain, low back pain or hip arthritis were significantly more prevalent than in lean women (P < 0.05). Morbidly obese women (BMI > 35 kg m(-2)N = 133) walked significantly slower (5.4 km h(-1)) than obese (5.9 km h(-1)) and lean women (7.2 km h(-1), P < 0.05), were more exerted (RPE 13.3, 12.8 and 12.4, respectively, P < 0.05) and complained more frequently of dyspnea (9.1%, 4.7% and 0% resp., P < 0.05) and musculoskeletal pain (34.9%, 17.7% and 11.4% resp

  13. North Star Ambulatory Assessment, 6-minute walk test and timed items in ambulant boys with Duchenne muscular dystrophy.

    PubMed

    Mazzone, Elena; Martinelli, Diego; Berardinelli, Angela; Messina, Sonia; D'Amico, Adele; Vasco, Gessica; Main, Marion; Doglio, Luca; Politano, Luisa; Cavallaro, Filippo; Frosini, Silvia; Bello, Luca; Carlesi, Adelina; Bonetti, Anna Maria; Zucchini, Elisabetta; De Sanctis, Roberto; Scutifero, Marianna; Bianco, Flaviana; Rossi, Francesca; Motta, Maria Chiara; Sacco, Annalisa; Donati, Maria Alice; Mongini, Tiziana; Pini, Antonella; Battini, Roberta; Pegoraro, Elena; Pane, Marika; Pasquini, Elisabetta; Bruno, Claudio; Vita, Giuseppe; de Waure, Chiara; Bertini, Enrico; Mercuri, Eugenio

    2010-11-01

    The North Star Ambulatory Assessment is a functional scale specifically designed for ambulant boys affected by Duchenne muscular dystrophy (DMD). Recently the 6-minute walk test has also been used as an outcome measure in trials in DMD. The aim of our study was to assess a large cohort of ambulant boys affected by DMD using both North Star Assessment and 6-minute walk test. More specifically, we wished to establish the spectrum of findings for each measure and their correlation. This is a prospective multicentric study involving 10 centers. The cohort included 112 ambulant DMD boys of age ranging between 4.10 and 17 years (mean 8.18±2.3 DS). Ninety-one of the 112 were on steroids: 37/91 on intermittent and 54/91 on daily regimen. The scores on the North Star assessment ranged from 6/34 to 34/34. The distance on the 6-minute walk test ranged from 127 to 560.6 m. The time to walk 10 m was between 3 and 15 s. The time to rise from the floor ranged from 1 to 27.5 s. Some patients were unable to rise from the floor. As expected the results changed with age and were overall better in children treated with daily steroids. The North Star assessment had a moderate to good correlation with 6-minute walk test and with timed rising from floor but less with 10 m timed walk/run test. The 6-minute walk test in contrast had better correlation with 10 m timed walk/run test than with timed rising from floor. These findings suggest that a combination of these outcome measures can be effectively used in ambulant DMD boys and will provide information on different aspects of motor function, that may not be captured using a single measure. PMID:20634072

  14. North Star Ambulatory Assessment, 6-minute walk test and timed items in ambulant boys with Duchenne muscular dystrophy.

    PubMed

    Mazzone, Elena; Martinelli, Diego; Berardinelli, Angela; Messina, Sonia; D'Amico, Adele; Vasco, Gessica; Main, Marion; Doglio, Luca; Politano, Luisa; Cavallaro, Filippo; Frosini, Silvia; Bello, Luca; Carlesi, Adelina; Bonetti, Anna Maria; Zucchini, Elisabetta; De Sanctis, Roberto; Scutifero, Marianna; Bianco, Flaviana; Rossi, Francesca; Motta, Maria Chiara; Sacco, Annalisa; Donati, Maria Alice; Mongini, Tiziana; Pini, Antonella; Battini, Roberta; Pegoraro, Elena; Pane, Marika; Pasquini, Elisabetta; Bruno, Claudio; Vita, Giuseppe; de Waure, Chiara; Bertini, Enrico; Mercuri, Eugenio

    2010-11-01

    The North Star Ambulatory Assessment is a functional scale specifically designed for ambulant boys affected by Duchenne muscular dystrophy (DMD). Recently the 6-minute walk test has also been used as an outcome measure in trials in DMD. The aim of our study was to assess a large cohort of ambulant boys affected by DMD using both North Star Assessment and 6-minute walk test. More specifically, we wished to establish the spectrum of findings for each measure and their correlation. This is a prospective multicentric study involving 10 centers. The cohort included 112 ambulant DMD boys of age ranging between 4.10 and 17 years (mean 8.18±2.3 DS). Ninety-one of the 112 were on steroids: 37/91 on intermittent and 54/91 on daily regimen. The scores on the North Star assessment ranged from 6/34 to 34/34. The distance on the 6-minute walk test ranged from 127 to 560.6 m. The time to walk 10 m was between 3 and 15 s. The time to rise from the floor ranged from 1 to 27.5 s. Some patients were unable to rise from the floor. As expected the results changed with age and were overall better in children treated with daily steroids. The North Star assessment had a moderate to good correlation with 6-minute walk test and with timed rising from floor but less with 10 m timed walk/run test. The 6-minute walk test in contrast had better correlation with 10 m timed walk/run test than with timed rising from floor. These findings suggest that a combination of these outcome measures can be effectively used in ambulant DMD boys and will provide information on different aspects of motor function, that may not be captured using a single measure.

  15. Does verbal encouragement actually improve performance in the 6-minute walk test?

    PubMed

    Marinho, Patrícia E M; Raposo, Maria Cristina; Dean, Elizabeth; Guerra, Ricardo O; de Andrade, Arméle Dornelas

    2014-11-01

    The purpose of this study was to evaluate the performance in the 6-minute walk test (6 MWT) of elderly patients with chronic obstructive pulmonary disease (COPD) by comparing to a group of healthy elderly patients, performed with and without verbal encouragement. This cross-sectional study compared 40 patients with COPD (forced expiratory volume in the first second (FEV1%) = 53.7 ± 23.8%; forced vital capacity (FVC%) = 65.5 ± 20.8%; and the FEV1/FVC ratio = 55.4 ± 12.4) and 40 healthy elderly patients (control). The 6 MWT's were performed with and without verbal encouragement according to the American Thoracic Society (ATS), monitoring the distance walked (6 MWD), the duration of walking (TW) and the perceived effort index (PEI) through the Borg scale between the groups. No differences were observed in patients with COPD when the tests were performed with and without verbal encouragement for the 6 MWD, TW and PEI, the same occurring in the control group for the 6 MWD, TW and PEI, respectively. The use of verbal encouragement was not sufficient to promote improvement in the performance of the 6 MWT (6 MWD, TW and PEI) of patients with COPD and healthy elderly patients.

  16. Impact of adherence to GOLD guidelines on 6-minute walk distance, MRC dyspnea scale score, lung function decline, quality of life, and quality-adjusted life years in a Shanghai suburb.

    PubMed

    Jiang, Y Q; Zhu, Y X; Chen, X L; Xu, X; Li, F; Fu, H J; Shen, C Y; Lu, Y Y; Zhuang, Q J; Xu, G; Cai, Y Y; Zhang, Y; Liu, S S; Zhu, M Y; Li, S H

    2015-01-01

    We performed a 1-year cluster-randomized field trial to assess the effect of standardized management of chronic obstructive pulmonary disease (COPD) on lung function and quality of life (QOL) measures in patients in China. We used the Global Initiative for Chronic Obstructive Lung Disease (GOLD) treatment guidelines and assessed indexes including pulmonary function, QOL, quality-adjusted life years (QALY), Medical Research Council (MRC) dyspnea scale, 6-min walk distance (6-MWD), number of emergency visits, and frequency of hospitalization. Of a total of 711 patients with chronic cough and asthma, 132 were diagnosed as having COPD and 102 participated in this study [intervention group (N = 47); control group (N = 55)]. We found that adherence to GOLD guidelines had a perceivable impact on 6-MWD, MRC dyspnea scale score, and QOL. The average QALY increased by 1.42/person/year in the intervention group, but declined by 0.95/person/year in the control group. We conclude that standardized management improves disease severity, QOL, and QALY in COPD patients when treatment protocols adhere to GOLD guidelines.

  17. Comparison between the 6-minute walk tests performed in patients with chronic obstructive pulmonary disease at different altitudes

    PubMed Central

    Squassoni, Selma Denis; Machado, Nadine Cristina; Lapa, Mônica Silveira; Cordoni, Priscila Kessar; Bortolassi, Luciene Costa; de Oliveira, Juliana Nascimento; Tavares, Cecilia Melo Rosa; Fiss, Elie

    2014-01-01

    Objective To evaluate the influence of the altitude on the 6-minute walking test in patients with moderate to severe pulmonary disease. Methods Twenty-nine patients performed the 6-minute walk test at a pulmonary rehabilitation clinic in Santo André (above sea level), in São Paulo State, and at the Enseada Beach, in Guarujá (at sea level), also in São Paulo State. Of these 29 patients, 8 did the test both on hard sand and on asphalt to analyze if there were differences in performance during the tests. Data such as heart rate, oxygen saturation, test distance, and Borg scale were compared. Results We found no statistical difference in relation to oxygen saturation at rest before the beginning of the walking test in Santo André 94.67±2.26% and at sea level 95.56±2% (p=0.71). The minimum saturation measured during the test was 87.27±6.54% in Santo André and 89.10±5.41% in Guarujá (p=0.098). There were no differences in the performed distance between the different kinds of terrains; the distance on sand was 387.75±5.02m and on asphalt it was 375.00±6.54m (p=0.654). Regarding oxygen saturation during walking, the pulse oximetry on sand was 95.12±1.80% and on asphalt it was 96.87±1.64% (p=1.05). Conclusion Altitude did not affect the performance of the walking test in patients with moderate to severe pulmonary disease and the results were similar in both cases, on sand and on asphalt. PMID:25628195

  18. Assessing Walking Ability in People with HTLV-1-Associated Myelopathy Using the 10 Meter Timed Walk and the 6 Minute Walk Test

    PubMed Central

    Adonis, Adine; Taylor, Graham P.

    2016-01-01

    Background Five to ten million persons, are infected by HTLV-1 of which 3% will develop HTLV-1-associated myelopathy (HAM) a chronic, disabling inflammation of the spinal cord. Walking, a fundamental, complex, multi-functional task is demanding of multiple body systems. Restricted walking ability compromises activity and participation levels in people with HAM (pwHAM). Therapy aims to improve mobility but validated measures are required to assess change. Study Design Prospective observational study. Objectives To explore walking capacity in pwHAM, walking endurance using the 6 minute walk (6MW), and gait speed, using the timed 10m walk (10mTW). Setting Out-patient setting in an inner London Teaching hospital. Methods Prospective documentation of 10mTW and 6MW distance; walking aid usage and pain scores measured twice, a median of 18 months apart. Results Data analysis was completed for twenty-six pwHAM, (8♂; 18♀; median age: 57.8 years; median disease duration: 8 years). Median time at baseline to: complete 10m was 17.5 seconds, versus 21.4 seconds at follow up; 23% completed the 6MW compared to 42% at follow up and a median distance of 55m was covered compared to 71m at follow up. Using the 10mTW velocity to predict the 6MW distance, overestimated the distance walked in 6 minutes (p<0.01). Functional decline over time was captured using the functional ambulation categories. Conclusions The 10mTW velocity underestimated the degree of disability. Gait speed usefully predicts functional domains, shows direction of functional change and comparison with published healthy age matched controls show that these patients have significantly slower gait speeds. The measured differences over 18 months were sufficient to reliably detect change and therefore these assessments can be useful to detect improvement or deterioration within broader disability grades. Walking capacity in pwHAM should be measured using the 10mTW for gait speed and the 6MW for endurance. PMID

  19. [Just 6 minutes to get to the heart of frailty: the walking test in geriatric cardiology].

    PubMed

    Gambassi, Giovanni; Cesari, Matteo; Tosato, Matteo; Bernabei, Roberto

    2013-03-01

    Frailty is a geriatric syndrome due to impaired physiological reserve and characterized by a reduced ability to cope with stressing situations. Frailty and cardiovascular diseases share a common biological pathway and cardiovascular conditions may facilitate the manifestation of clinical frailty. Frailty is identified in 25% to 50% of patients with cardiovascular diseases, with estimates varying depending on assessment methods and population under study. Frail patients with cardiovascular diseases, especially those undergoing invasive procedures, particularly because of coronary artery disease or heart failure, have a substantially higher likelihood of complications and adverse events when compared to robust patients. Gait speed is a simple and reliable measure for objectively identifying frailty in elderly patients with cardiovascular diseases. A performance marker like the 6-minute walking test should be considered for routine use as a prognostic indicator.

  20. Are the 10 Meter and 6 Minute Walk Tests Redundant in Patients with Spinal Cord Injury?

    PubMed Central

    Forrest, Gail F.; Hutchinson, Karen; Lorenz, Douglas J.; Buehner, Jeffrey J.; VanHiel, Leslie R.; Sisto, Sue Ann; Basso, D. Michele

    2014-01-01

    Objective To evaluate the relationship and redundancy between gait speeds measured by the 10 Meter Walk Test (10MWT) and 6 Minute Walk Test (6MWT) after motor incomplete spinal cord injury (iSCI). To identify gait speed thresholds supporting functional ambulation as measured with the Spinal Cord Injury Functional Ambulation Inventory (SCI-FAI). Design Prospective observational cohort. Setting Seven outpatient rehabilitation centers from the Christopher and Dana Reeve Foundation NeuroRecovery Network (NRN). Participants 249 NRN patients with American Spinal Injury Association Impairment Scale (AIS) level C (n = 20), D (n = 179) and (n = 50) iSCI not AIS evaluated, from February 2008 through April 2011. Interventions Locomotor training using body weight support and walking on a treadmill, overground and home/community practice. Main Outcome Measure(s) 10MWT and 6MWT collected at enrollment, approximately every 20 sessions, and upon discharge. Results The 10MWT and 6MWT speeds were highly correlated and the 10MWT speeds were generally faster. However, the predicted 6MWT gait speed from the 10MWT, revealed increasing error with increased gait speed. Regression lines remained significantly different from lines of agreement, when the group was divided into fast (≥0.44 m/s) and slow walkers (<0.44 m/s). Significant differences between 6MWT and 10MWT gait speeds were observed across SCI-FAI walking mobility categories (Wilcoxon sign rank test p<.001), and mean speed thresholds for limited community ambulation differed for each measure. The smallest real difference for the 6MWT and 10MWT, as well as the minimally clinically important difference (MCID) values, were also distinct for the two tests. Conclusions While the speeds were correlated between the 6MWT and 10MWT, redundancy in the tests using predictive modeling was not observed. Different speed thresholds and separate MCIDs were defined for community ambulation for each test. PMID:24788068

  1. A comparison of the shuttle and 6 minute walking tests with measured peak oxygen consumption in patients with heart failure.

    PubMed

    Green, D J; Watts, K; Rankin, S; Wong, P; O'Driscoll, J G

    2001-09-01

    This study investigated the use of an incremental, externally-paced 10 m shuttle walk test (SWT) as an objective, reliable and predictive test of functional capacity in patients with heart failure (CHF). The SWT was compared to a 6 minute walk test (6WT) and a maximal symptom-limited treadmill peak oxygen consumption (VO2peak) test. Experiment 1 examined the reproducibility of the SWT. Two SWF trials were performed and distance ambulated (DA), heart rate (HR) and rate of perceived exertion (RPE) results compared. In experiment 2, SWT, 6WT, and VO2 peak tests were performed and HR. RPE and ambulatory VO2 compared. The SWT demonstrated strong test/retest reliability for DA (r = 0.98). HR (r = 0.96) and RPE (r = 0.89). Treadmill VO2 peak was significantly correlated with DA during the SWT (r = 0.83, P < 0.05), but not the 6WT. SWT peak VO2 (18.5 +/- 1.8 ml.kg(-1) x min(-1)) and treadmill VO2 peak (18.3 +/-2.0 ml.kg(-1) x min(-1)) were also highly correlated (r = 0.78, P < 0.05). Conversely, 6WT peak VO2 and treadmill VO2 peak were not significantly correlated. This study suggests the SWT is a reliable, objective test, highly predictive of VO2 peak which may be a more optimal field exercise test than the self paced 6WT.

  2. [Application of the 6-Minute Walking Test and Shuttle Walking Test in the Exercise Tests of Patients With COPD].

    PubMed

    Ho, Chiung-Fang; Maa, Suh-Hwa

    2016-08-01

    Exercise training improves the management of stable chronic obstructive pulmonary disease (COPD). COPD patients benefit from exercise training programs in terms of improved VO2 peak values and decreased dyspnea, fatigue, hospital admissions, and rates of mortality, increasing exercise capacity and health-related quality of life (HRQOL). COPD is often associated with impairment in exercise tolerance. About 51% of patients have a limited capacity for normal activity, which often further degrades exercise capacity, creating a vicious circle. Exercise testing is highly recommended to assess a patient's individualized functions and limitations in order to determine the optimal level of training intensity prior to initiating an exercise-training regimen. The outcomes of exercise testing provide a powerful indicator of prognosis in COPD patients. The six-minute walking test (6MWT) and the incremental shuttle-walking test (ISWT) are widely used in exercise testing to measure a patient's exercise ability by walking distances. While nursing-related articles published in Taiwan frequently cite and use the 6MWT to assess exercise capacity in COPD patients, the ISWT is rarely used. This paper introduces the testing method, strengths and weaknesses, and application of the two tests in order to provide clinical guidelines for assessing the current exercise capacity of COPD patients. PMID:27492301

  3. Test-Retest Reliability of the 10-Metre Fast Walk Test and 6-Minute Walk Test in Ambulatory School-Aged Children with Cerebral Palsy

    ERIC Educational Resources Information Center

    Thompson, Patricia; Beath, Tricia; Bell, Jacqueline; Jacobson, Gabrielle; Phair, Tegan; Salbach, Nancy M.; Wright, F. Virginia

    2008-01-01

    Short-term test-retest reliability of the 10-metre fast walk test (10mFWT) and 6-minute walk test (6MWT) was evaluated in 31 ambulatory children with cerebral palsy (CP), with subgroup analyses in Gross Motor Function Classification System (GMFCS) Levels I (n=9), II (n=8), and III (n=14). Sixteen females and 15 males participated, mean age 9 years…

  4. THE 6-MINUTE WALK TEST AND OTHER CLINICAL ENDPOINTS IN DUCHENNE MUSCULAR DYSTROPHY: RELIABILITY, CONCURRENT VALIDITY, AND MINIMAL CLINICALLY IMPORTANT DIFFERENCES FROM A MULTICENTER STUDY

    PubMed Central

    McDonald, Craig M; Henricson, Erik K; Abresch, R Ted; Florence, Julaine; Eagle, Michelle; Gappmaier, Eduard; Glanzman, Allan M; Spiegel, Robert; Barth, Jay; Elfring, Gary; Reha, Allen; Peltz, Stuart W

    2013-01-01

    Introduction: An international clinical trial enrolled 174 ambulatory males ≥5 years old with nonsense mutation Duchenne muscular dystrophy (nmDMD). Pretreatment data provide insight into reliability, concurrent validity, and minimal clinically important differences (MCIDs) of the 6-minute walk test (6MWT) and other endpoints. Methods: Screening and baseline evaluations included the 6-minute walk distance (6MWD), timed function tests (TFTs), quantitative strength by myometry, the PedsQL, heart rate–determined energy expenditure index, and other exploratory endpoints. Results: The 6MWT proved feasible and reliable in a multicenter context. Concurrent validity with other endpoints was excellent. The MCID for 6MWD was 28.5 and 31.7 meters based on 2 statistical distribution methods. Conclusions: The ratio of MCID to baseline mean is lower for 6MWD than for other endpoints. The 6MWD is an optimal primary endpoint for Duchenne muscular dystrophy (DMD) clinical trials that are focused therapeutically on preservation of ambulation and slowing of disease progression. Muscle Nerve 48: 357–368, 2013 PMID:23674289

  5. THE 6-MINUTE WALK TEST AND OTHER ENDPOINTS IN DUCHENNE MUSCULAR DYSTROPHY: LONGITUDINAL NATURAL HISTORY OBSERVATIONS OVER 48 WEEKS FROM A MULTICENTER STUDY

    PubMed Central

    Mcdonald, Craig M; Henricson, Erik K; Abresch, R Ted; Florence, Julaine M; Eagle, Michelle; Gappmaier, Eduard; Glanzman, Allan M; Spiegel, Robert; Barth, Jay; Elfring, Gary; Reha, Allen; Peltz, Stuart

    2013-01-01

    Introduction: Duchenne muscular dystrophy (DMD) subjects ≥5 years with nonsense mutations were followed for 48 weeks in a multicenter, randomized, double-blind, placebo-controlled trial of ataluren. Placebo arm data (N = 57) provided insight into the natural history of the 6-minute walk test (6MWT) and other endpoints. Methods: Evaluations performed every 6 weeks included the 6-minute walk distance (6MWD), timed function tests (TFTs), and quantitative strength using hand-held myometry. Results: Baseline age (≥7 years), 6MWD, and selected TFT performance are strong predictors of decline in ambulation (Δ6MWD) and time to 10% worsening in 6MWD. A baseline 6MWD of <350 meters was associated with greater functional decline, and loss of ambulation was only seen in those with baseline 6MWD <325 meters. Only 1 of 42 (2.3%) subjects able to stand from supine lost ambulation. Conclusion: Findings confirm the clinical meaningfulness of the 6MWD as the most accepted primary clinical endpoint in ambulatory DMD trials. PMID:23681930

  6. Reproducibility and Validity of the 6-Minute Walk Test Using the Gait Real-Time Analysis Interactive Lab in Patients with COPD and Healthy Elderly

    PubMed Central

    Meijer, Kenneth; Delbressine, Jeannet M.; Willems, Paul J.; Franssen, Frits M. E.; Wouters, Emiel F. M.; Spruit, Martijn A.

    2016-01-01

    Background The 6-minute walk test (6MWT) in a regular hallway is commonly used to assess functional exercise capacity in patients with chronic obstructive pulmonary disease (COPD). However, treadmill walking might provide additional advantages over overground walking, especially if virtual reality and self-paced treadmill walking are combined. Therefore, this study aimed to assess the reproducibility and validity of the 6MWT using the Gait Real-time Analysis Interactive Lab (GRAIL) in patients with COPD and healthy elderly. Methodology/Results Sixty-one patients with COPD and 48 healthy elderly performed two 6MWTs on the GRAIL. Patients performed two overground 6MWTs and healthy elderly performed one overground test. Differences between consecutive 6MWTs and the test conditions (GRAIL vs. overground) were analysed. Patients walked further in the second overground test (24.8 m, 95% CI 15.2–34.4 m, p<0.001) and in the second GRAIL test (26.8 m, 95% CI 13.9–39.6 m). Healthy elderly improved their second GRAIL test (49.6 m, 95% CI 37.0–62.3 m). The GRAIL 6MWT was reproducible (intra-class coefficients = 0.65–0.80). The best GRAIL 6-minute walk distance (6MWD) in patients was shorter than the best overground 6MWD (-27.3 ± 49.1 m, p<0.001). Healthy elderly walked further on the GRAIL than in the overground condition (23.6 ± 41.4 m, p<0.001). Validity of the GRAIL 6MWT was assessed and intra-class coefficient values ranging from 0.74–0.77 were found. Conclusion The GRAIL is a promising system to assess the 6MWD in patients with COPD and healthy elderly. The GRAIL 6MWD seems to be more comparable to the 6MWDs assessed overground than previous studies on treadmills have reported. Furthermore, good construct validity and reproducibility were established in assessing the 6MWD using the GRAIL in patients with COPD and healthy elderly. PMID:27607426

  7. Dynamic hyperinflation and dyspnea during the 6-minute walk test in stable chronic obstructive pulmonary disease patients.

    PubMed

    Satake, Masahiro; Shioya, Takanobu; Uemura, Sachiko; Takahashi, Hitomi; Sugawara, Keiyu; Kasai, Chikage; Kiyokawa, Noritaka; Watanabe, Toru; Sato, Sayaka; Kawagoshi, Atsuyoshi

    2015-01-01

    The purpose of this study was to investigate the relationship between dynamic hyperinflation and dyspnea and to clarify the characteristics of dyspnea during the 6-minute walk test (6MWT) in chronic obstructive pulmonary disease patients. Twenty-three subjects with stable moderate chronic obstructive pulmonary disease (age 73.8±5.8 years, all male) took part in this study. During the 6MWT, ventilatory and gas exchange parameters were measured using a portable respiratory gas analysis system. Dyspnea and oxygen saturation were recorded at the end of every 2 minute period during the test. There was a significant decrease in inspiratory capacity during the 6MWT. This suggested that dynamic hyperinflation had occurred. Dyspnea showed a significant linear increase, and there was a significant negative correlation with inspiratory capacity. It was suggested that one of the reasons that dyspnea developed during the 6MWT was the dynamic hyperinflation. Even though the tidal volume increased little after 2 minutes, dyspnea increased linearly to the end of the 6MWT. These results suggest that the mechanisms generating dyspnea during the 6MWT were the sense of respiratory effort at an early stage and then the mismatch between central motor command output and respiratory system movement.

  8. Combined therapy with tiotropium and formoterol in chronic obstructive pulmonary disease: effect on the 6-minute walk test.

    PubMed

    Jayaram, Lata; Wong, Conroy; McAuley, Sue; Rea, Harry; Zeng, Irene; O'Dochartaigh, Conor

    2013-08-01

    Combined therapy with tiotropium and long-acting beta 2 agonists confers additional improvement in symptoms, lung function and aspects of health-related quality of life (QOL) compared with each drug alone in patients with COPD. However, the efficacy of combined therapy on walking distance, a surrogate measure of daily functional activity and morbidity remains unclear. The aim was, therefore, to quantify the benefit of this therapy on the six minute walk test. Secondary outcomes included change in lung function, symptoms, the BODE index and QOL. In a double-blind, crossover study, 38 participants with moderate to severe COPD on tiotropium were randomised to receive either formoterol or placebo for 6 weeks. Following a 2-week washout period, participants crossed over to the alternate arm of therapy for a further 6 weeks. Thirty-six participants, with an average age of 64.3 years and FEV1 predicted of 53%, completed the study. Combined therapy improved walking distance by a mean of 36 metres [95% CI: 2.4, 70.1; p = 0.04] compared with tiotropium. FEV1 increased in both groups (160 mL combination therapy versus 30 mL tiotropium) with a mean difference of 110 mL (95% CI: -100, 320; p = 0.07) between groups, These findings further support the emerging advantages of combined therapy in COPD. Australian New Zealand Clinical Trials. PMID:23875741

  9. Performance in the 6-minute walk test and postoperative pulmonary complications in pulmonary surgery: an observational study

    PubMed Central

    Santos, Bruna F. A.; Souza, Hugo C. D.; Miranda, Aline P. B.; Cipriano, Federico G.; Gastaldi, Ada C.

    2016-01-01

    OBJECTIVES: To assess functional capacity in the preoperative phase of pulmonary surgery by comparing predicted and obtained values for the six-minute walk test (6MWT) in patients with and without postoperative pulmonary complication (PPC) METHOD: Twenty-one patients in the preoperative phase of open thoracotomy were evaluated using the 6MWT, followed by monitoring of the postoperative evolution of each participant who underwent the routine treatment. Participants were then divided into two groups: the group with PPC and the group without PPC. The results were also compared with the predicted values using reference equations for the 6MWT RESULTS: Over half (57.14%) of patients developed PPC. The 6MWT was associated with the odds for PPC (odds ratio=22, p=0.01); the group without PPC in the postoperative period walked 422.38 (SD=72.18) meters during the 6MWT, while the group with PPC walked an average of 340.89 (SD=100.93) meters (p=0.02). The distance traveled by the group without PPC was 80% of the predicted value, whereas the group with PPC averaged less than 70% (p=0.03), with more appropriate predicted values for the reference equations CONCLUSIONS: The 6MWT is an easy, safe, and feasible test for routine preoperative evaluation in pulmonary surgery and may indicate patients with a higher chance of developing PPC. PMID:26786074

  10. Does the 6-minute walk test predict nocturnal oxygen desaturation in patients with moderate to severe COPD?

    PubMed

    Iliaz, Sinem; Cagatay, Tulin; Bingol, Zuleyha; Okumus, Gulfer; Iliaz, Raim; Kuran, Goksen; Kiyan, Esen; Cagatay, Penbe

    2015-02-01

    Patients with chronic obstructive pulmonary disease (COPD) who have nocturnal oxygen desaturation (NOD) can be treated with nocturnal oxygen therapy (NOT) to avoid possible morbidity and mortality. Although there is no definite data recommending NOT alone, our aim is to evaluate the relationship between desaturation during the six-minute walk test (6MWT) and NOD in COPD. Fifty-five stable patients with COPD were enrolled in this study. The 6MWT and nocturnal oximetry were performed. Patients with comorbid diseases and respiratory failure were excluded. In total, 55 patients (49 males and 6 females, mean age: 65.8 ± 8.4 years) were analysed. Twenty-seven of the patients had moderate COPD and the remainder (n = 28) had severe COPD. Three patients (11%) with moderate COPD and 12 patients (42.9%) with severe COPD desaturated during 6MWT (p = 0.003). NOD was observed in five patients with severe COPD (17.9%). There were no patients with NOD in the moderate COPD group. Three (25%) of patients with severe COPD who desaturated during the 6MWT also had NOD. NOD was more common in patients with severe COPD and the patients with higher carbon dioxide levels (p = 0.02 and p = 0.001). Three patients (11%) with moderate COPD desaturated during the 6MWT; however they did not have NOD. Although the sample size in this study was too small to be conclusive, NOD was more common in desaturators during the 6MWT particularly in patients with severe COPD. PMID:25480424

  11. [Interpretation and use of routine pulmonary function tests: Spirometry, static lung volumes, lung diffusion, arterial blood gas, methacholine challenge test and 6-minute walk test].

    PubMed

    Bokov, P; Delclaux, C

    2016-02-01

    Resting pulmonary function tests (PFT) include the assessment of ventilatory capacity: spirometry (forced expiratory flows and mobilisable volumes) and static volume assessment, notably using body plethysmography. Spirometry allows the potential definition of obstructive defect, while static volume assessment allows the potential definition of restrictive defect (decrease in total lung capacity) and thoracic hyperinflation (increase in static volumes). It must be kept in mind that this evaluation is incomplete and that an assessment of ventilatory demand is often warranted, especially when facing dyspnoea: evaluation of arterial blood gas (searching for respiratory insufficiency) and measurement of the transfer coefficient of the lung, allowing with the measurement of alveolar volume to calculate the diffusing capacity of the lung for CO (DLCO: assessment of alveolar-capillary wall and capillary blood volume). All these pulmonary function tests have been the subject of an Americano-European Task force (standardisation of lung function testing) published in 2005, and translated in French in 2007. Interpretative strategies for lung function tests have been recommended, which define abnormal lung function tests using the 5th and 95th percentiles of predicted values (lower and upper limits of normal values). Thus, these recommendations need to be implemented in all pulmonary function test units. A methacholine challenge test will only be performed in the presence of an intermediate pre-test probability for asthma (diagnostic uncertainty), which is an infrequent setting. The most convenient exertional test is the 6-minute walk test that allows the assessment of walking performance, the search for arterial desaturation and the quantification of dyspnoea complaint.

  12. Oxygen desaturation during a 6-minute walk test as a predictor of maximal exercise-induced gas exchange abnormalities in sarcoidosis

    PubMed Central

    Chenivesse, Cecile; Boulanger, Sarah; Langlois, Carole; Wemeau-Stervinou, Lidwine; Perez, Thierry

    2016-01-01

    Background Common tests for evaluating gas exchange impairment have different strengths and weaknesses. Alveolar-to-arterial oxygen pressure difference (AaDO2) at peak exercise is a sensitive indicator but it cannot be measured repeatedly. Diffusing capacity of the lung for carbon monoxide (DLco) is measured at rest and may be too insensitive to predict the effects of exercise on gas exchange impairment. Oxygen desaturation during a 6-minute walk test (∆SpO2-6MWT) can be measured repeatedly, but its value in sarcoidosis is unknown. Here, we evaluated the ability of ∆SpO2-6MWT and DLco to predict gas exchange impairment during exercise in sarcoidosis. Methods This retrospective study of 130 subjects with sarcoidosis investigated the relationship between DLco, ∆SpO2-6MWT, and peak AaDO2 using correlation tests, inter-test reliability analyses, and predictive values. For the analyses of inter-test reliability and predictive values, DLco, peak AaDO2, and ∆SpO2-6MWT were considered as binary variables (normal/abnormal) according to previously defined thresholds. Results Correlation coefficients between DLco, ∆SpO2-6MWT, and peak AaDO2 were intermediate (0.53–0.67, P<0.0003) and Kappa coefficients were low (0.21–0.42, P=0.0003–0.02). DLco predicted (I) increased peak AaDO2 with a positive predictive value (PPV) of 66% and a negative predictive value (NPV) of 78% and (II) increased ∆SpO2-6MWT with a PPV at 36% and an NPV at 88%. Normal DLco was a good predictor of the absence of severe desaturation during the 6MWT (94% NPV) and at peak exercise during cardiopulmonary exercise test (CPET) (100% NPV). ∆SpO2-6MWT predicted peak AaDO2 increase with a PPV of 74% and an NPV of 60%. Conclusions In a large population of sarcoidosis patients, neither ∆SpO2-6MWT nor DLco was a good predictor of increased peak AaDO2. In contrast, normal DLco was a good predictor of the absence of severe desaturation during the 6MWT and at peak exercise during CPET.

  13. Oxygen desaturation during a 6-minute walk test as a predictor of maximal exercise-induced gas exchange abnormalities in sarcoidosis

    PubMed Central

    Chenivesse, Cecile; Boulanger, Sarah; Langlois, Carole; Wemeau-Stervinou, Lidwine; Perez, Thierry

    2016-01-01

    Background Common tests for evaluating gas exchange impairment have different strengths and weaknesses. Alveolar-to-arterial oxygen pressure difference (AaDO2) at peak exercise is a sensitive indicator but it cannot be measured repeatedly. Diffusing capacity of the lung for carbon monoxide (DLco) is measured at rest and may be too insensitive to predict the effects of exercise on gas exchange impairment. Oxygen desaturation during a 6-minute walk test (∆SpO2-6MWT) can be measured repeatedly, but its value in sarcoidosis is unknown. Here, we evaluated the ability of ∆SpO2-6MWT and DLco to predict gas exchange impairment during exercise in sarcoidosis. Methods This retrospective study of 130 subjects with sarcoidosis investigated the relationship between DLco, ∆SpO2-6MWT, and peak AaDO2 using correlation tests, inter-test reliability analyses, and predictive values. For the analyses of inter-test reliability and predictive values, DLco, peak AaDO2, and ∆SpO2-6MWT were considered as binary variables (normal/abnormal) according to previously defined thresholds. Results Correlation coefficients between DLco, ∆SpO2-6MWT, and peak AaDO2 were intermediate (0.53–0.67, P<0.0003) and Kappa coefficients were low (0.21–0.42, P=0.0003–0.02). DLco predicted (I) increased peak AaDO2 with a positive predictive value (PPV) of 66% and a negative predictive value (NPV) of 78% and (II) increased ∆SpO2-6MWT with a PPV at 36% and an NPV at 88%. Normal DLco was a good predictor of the absence of severe desaturation during the 6MWT (94% NPV) and at peak exercise during cardiopulmonary exercise test (CPET) (100% NPV). ∆SpO2-6MWT predicted peak AaDO2 increase with a PPV of 74% and an NPV of 60%. Conclusions In a large population of sarcoidosis patients, neither ∆SpO2-6MWT nor DLco was a good predictor of increased peak AaDO2. In contrast, normal DLco was a good predictor of the absence of severe desaturation during the 6MWT and at peak exercise during CPET. PMID

  14. 013. Complementary role of 6-minutes walking test (6MWT) in the assessment of functional status of patients with chronic obstructive pulmonary disease (COPD)

    PubMed Central

    Mathioudakis, Alexander G.; Evangelopoulou, Efstathia I.; Karapiperis, Georgios C.; Perros, Elias I.; Simou, Georgia; Kiritsi, Evridiki; Chatzimavridou-Grigoriadou, Victoria; Mathioudakis, Georgios A.

    2015-01-01

    Background Despite its limited repeatability, spirometry is the most widely used method of assessment of the pulmonary ventilation. However, it is not a safe measure of the functional reserve of chronic obstructive pulmonary disease (COPD) patients with multiple comorbidities. Consequently, a stress test that would include cardiovascular and neuromuscular variables would be a useful complimentary test. Objective The aim of this observational study was to investigate the correlation between FEV1 and 6MWT, in patients with stable COPD (mean FEV1% pred =43.9%, SD =15.3). Methods 174 male ex-smokers with stable COPD, with a mean age of 63±6.7 years, mean height of 171.4 and weight of 73.9 were included and grouped according to their GOLD severity staging. A control group consisting of 87 healthy volunteers (mean age: 64±6.2, height: 175.2 and weight: 70.5) was also included. All the patient and controls had spirometry before and after bronchodilatation, on a daily scaled turbine spirometer, and 6MWT, on a 10-meter straight corridor. Elapsed distance (eD), haemoglobin saturation (Sats) and heart rate (HR) were continuously monitored during the 6MWT. All the data of our study were imported in an excel sheet for statistical analysis. Results Among the main results of our study, FEV1 decrease by year of age was less pronounced among healthy volunteers (21 mL/year, r2=0.4) compared to COPD patients (53 mL/year, r2=0.06). Similarly, volunteers had a significantly lower decrease by year of age in eD (2.3 m/year, r2=0.4) compared to COPD patients (7.7 m/year, r2=0.7). A more pronounced decrease of eD by year of age was recognized in patients with later COPD stages, while weight was more significantly correlated to eD compared to age. Post-bronchodilatation FEV1 was correlated to eD in COPD patients (r2=0.7); for each 1% decrease in the FEV1, COPD patients also lose approximately 7 m of walking distance in 6MWT. Conclusions 6MWT is a reliable measure of COPD progression and

  15. Do Improvements in Balance Relate to Improvements in Long-Distance Walking Function after Stroke?

    PubMed Central

    Awad, Louis N.; Reisman, Darcy S.; Binder-Macleod, Stuart A.

    2014-01-01

    Stroke survivors identify a reduced capacity to walk farther distances as a factor limiting their engagement at home and in community. Previous observational studies have shown that measures of balance ability and balance self-efficacy are strong predictors of long-distance walking function after stroke. Consequently, recommendations to target balance during rehabilitation have been put forth. The purpose of this study was to determine if the changes in balance and long-distance walking function observed following a 12-week poststroke walking rehabilitation program were related. For thirty-one subjects with hemiparesis after stroke, this investigation explored the cross-sectional (i.e., before training) and longitudinal (i.e., changes due to intervention) relationships between measures of standing balance, walking balance, and balance self-efficacy versus long-distance walking function as measured via the 6-minute walk test (6MWT). A regression model containing all three balance variables accounted for 60.8% of the variance in 6MWT performance (adjR2 = .584; F(3,27) = 13.931; P < .001); however, only dynamic balance (FGA) was an independent predictor (β = .502) of 6MWT distance. Interestingly, changes in balance were unrelated to changes in the distance walked (each correlation coefficient <.17, P > .05). For persons after stroke similar to those studied, improving balance may not be sufficient to improve long-distance walking function. PMID:25120939

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

    PubMed

    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.

  17. Visual estimation of travel distance during walking.

    PubMed

    Lappe, Markus; Frenz, Harald

    2009-12-01

    The optic flow generated in the eyes during self-motion provides an important control signal for direction and speed of self-motion, and can be used to track the distance that has been traveled. The use of vision for these behavioral tasks can be studied in isolation in virtual reality setups, in which self-motion is merely simulated, and in which the visual motion can be controlled independently of other sensory cues. In such experiments it was found that the estimation of the travel distance of a simulated movement shows characteristic errors, sometimes overestimating and sometimes underestimating the true travel distance. These errors can be explained by a leaky path integration model. To test whether this model also holds for actual self-motion in the real world we studied walking distance perception in an open field with tasks similar to those previously used in virtual environments. We show that similar errors occur in the estimation of travel distance in the real world as in virtual environment, and that they are consistent with the leaky integration model.

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

    PubMed Central

    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

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

    PubMed

    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

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

    PubMed Central

    Ho, Shu-Chuan; Hsu, Min-Fang; Kuo, Han-Pin; Wang, Jiun-Yi; Chen, Li-Fei; Lee, Kang-Yun; Chuang, Hsiao-Chi

    2015-01-01

    Background 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 intolerance according to logistic regression models that controlled for potential confounders. Conclusion Among the three variables examined, CC and walking distance may have the strongest association in COPD patients. CC may have value in serving as an adjunct to 6MWD in evaluating exercise intolerance of patients with COPD. PMID:26392760

  1. Walking for Transportation: What do U.S. Adults Think is a Reasonable Distance and Time?

    PubMed Central

    Watson, Kathleen B; Carlson, Susan A; Humbert-Rico, Tiffany; Carroll, Dianna D.; Fulton, Janet E

    2015-01-01

    Background Less than one-third of U.S. adults walk for transportation. Public health strategies to increase transportation walking would benefit from knowing what adults think is a reasonable distance to walk. Our purpose was to determine (1) what adults think is a reasonable distance and amount of time to walk and (2) whether there were differences in minutes spent transportation walking by what adults think is reasonable. Methods Analyses used a cross-sectional nationwide adult sample (n=3,653) participating in the 2010 Summer ConsumerStyles mail survey. Results Most adults (>90%) think transportation walking is reasonable. However, less than half (43%) think walking a mile or more or for 20 minutes or more is reasonable. What adults think is reasonable is similar across most demographic subgroups, except for older adults (≥ 65 years) who think shorter distances and times are reasonable. Trend analysis that adjust for demographic characteristics indicates adults who think longer distances and times are reasonable walk more. Conclusions Walking for short distances is acceptable to most U.S. adults. Public health programs designed to encourage longer distance trips may wish to improve supports for transportation walking to make walking longer distances seem easier and more acceptable to most U.S. adults. PMID:25158016

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

    PubMed

    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.

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

    PubMed Central

    Holdgate, Matthew R.; Meehan, Cheryl L.; Hogan, Jennifer N.; Miller, Lance J.; Soltis, Joseph; Andrews, Jeff; Shepherdson, David J.

    2016-01-01

    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. PMID:27414411

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

    PubMed

    Holdgate, Matthew R; Meehan, Cheryl L; Hogan, Jennifer N; Miller, Lance J; Soltis, Joseph; Andrews, Jeff; Shepherdson, David J

    2016-01-01

    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. PMID:27414411

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

    PubMed

    Holdgate, Matthew R; Meehan, Cheryl L; Hogan, Jennifer N; Miller, Lance J; Soltis, Joseph; Andrews, Jeff; Shepherdson, David J

    2016-01-01

    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.

  6. Advantage of distance- versus time-based estimates of walking in predicting adiposity

    PubMed Central

    Williams, Paul T.

    2013-01-01

    Purpose Physical activity recommendations are defined in terms of time spent being physically active (e.g., 30 minutes brisk walking, five days a week). However, walking volume may be more naturally assessed by distance than time. Analyses were therefore performed to test whether time or distance provide the best metric for relating walking volume to estimated total and regional adiposity. Methods Linear and logistic regression analyses were used to relate exercise dose to body mass index (BMI), body circumferences, and obesity in a cross-sectional sample of 12,384 female and 3,434 male walkers who reported both usual distance walked and time spent walking per week on survey questionnaires. Metabolic equivalent hours per day (METhr/d, 1 MET=3.5 ml O2•kg−1•min−1) were calculated from the time and pace, or distance and pace, using published compendium values. Results: Average METhr/d walked was 37% greater when calculated from time spent walking vs. usual distance in women, and 31% greater in men. Per METhr/d, declines in BMI and circumferences (slope±SE) were nearly twice as great, or greater, for distance- vs. time-derived estimates for kg/m2 of BMI (females: −0.58±0.03 vs. −0.31±0.02; males: −0.35±0.04 vs. −0.15±0.02), cm of waist circumference (females: −1.42±0.07 vs. −0.72±0.04; males: −0.96±0.10 vs. −0.45±0.07), and reductions in the odds for total obesity (odds ratio, females: 0.72 vs. 0.84; males: 0.84 vs. 0.92), and abdominal obesity (females: 0.74 vs. 0.85; males: 0.79 vs. 0.91, all comparisons significant). Conclusion Distance walked may provide a better metric of walking volume for epidemiologic obesity research, and better public health targets for weight control, than walking duration. Additional research is required to determine whether these results, derived in a sample that regularly walks for exercise, apply more generally. PMID:22525767

  7. Flexible kinesthetic distance perception: when do your arms tell you how far you have walked?

    PubMed

    Harrison, Steven J; Kuznetsov, Nikita; Breheim, Samuel

    2013-01-01

    Given the flexible organization of locomotion evidenced in the many ways the limbs can be coordinated, the authors explored the potentially correspondingly flexible organization of nonvisual (kinesthetic) distance perception. As kinesthetic distance perception is known to be affected by how the limbs are coordinated, the authors probed the potential perceptual contribution of the arms during locomotion by manipulating arm-leg coordination patterns in blind-walked distance-matching tasks. Whereas manipulation of arm-leg coordination for walking with free-swinging arms had no observable perceptual consequences, comparable manipulation for walking with hiking poles did affect distance matching. These results suggest that under conditions in which the arms act to propel the body (e.g., crawling or stair-climbing) a person's nonvisual sense of movement is conveyed in the coordinated actions of all four limbs.

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

    ERIC Educational Resources Information Center

    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…

  9. Can a Six-Minute Walk Distance Predict Right Ventricular Dysfunction in Patients with Diffuse Parenchymal Lung Disease and Pulmonary Hypertension?

    PubMed Central

    Ussavarungsi, Kamonpun; Lee, Augustine S.; Burger, Charles D.

    2016-01-01

    Objectives Pulmonary hypertension (PH) is commonly observed in patients with diffuse parenchymal lung disease (DPLD). The purpose of this study was to explore the influence of the 6-minute walk test (6MWT) as a simple, non-invasive tool to assess right ventricular (RV) function in patients with DPLD and to identify the need for an echocardiogram (ECHO) to screen for PH. Methods We retrospectively reviewed 48 patients with PH secondary to DPLD, who were evaluated in the PH clinic at the Mayo Clinic in Jacksonville, Florida, from January 1999 to December 2014. Results Fifty-two percent of patients had RV dysfunction. They had a significantly greater right heart pressure by ECHO and mean pulmonary arterial pressure (MPAP) from right heart catheterization (RHC) than those with normal RV function. A reduced 6-minute walk distance (6MWD) did not predict RV dysfunction (OR 0.995; 95% CI 0.980–1.001, p = 0.138). In addition, worsening restrictive physiology, heart rate at one-minute recovery and desaturation were not different between patients with and without RV dysfunction. However, there were inverse correlations between 6MWD and MPAP from RHC (r = -0.41, 
p = 0.010), 6MWD and RV systolic pressure (r = -0.51, p < 0.001), and 6MWD and MPAP measured by ECHO (r = -0.46, p =0.013). We also found no significant correlation between 6MWD and pulmonary function test parameters. Conclusions Our single-center cohort of patients with PH secondary to DPLD, PH was found to have an impact on 6MWD. In contrast to our expectations, 6MWD was not useful to predict RV dysfunction. Interestingly, a severe reduction in the 6MWD was related to PH and not to pulmonary function; therefore, it may be used to justify an ECHO to identify patients with a worse prognosis. PMID:27602188

  10. Can a Six-Minute Walk Distance Predict Right Ventricular Dysfunction in Patients with Diffuse Parenchymal Lung Disease and Pulmonary Hypertension?

    PubMed Central

    Ussavarungsi, Kamonpun; Lee, Augustine S.; Burger, Charles D.

    2016-01-01

    Objectives Pulmonary hypertension (PH) is commonly observed in patients with diffuse parenchymal lung disease (DPLD). The purpose of this study was to explore the influence of the 6-minute walk test (6MWT) as a simple, non-invasive tool to assess right ventricular (RV) function in patients with DPLD and to identify the need for an echocardiogram (ECHO) to screen for PH. Methods We retrospectively reviewed 48 patients with PH secondary to DPLD, who were evaluated in the PH clinic at the Mayo Clinic in Jacksonville, Florida, from January 1999 to December 2014. Results Fifty-two percent of patients had RV dysfunction. They had a significantly greater right heart pressure by ECHO and mean pulmonary arterial pressure (MPAP) from right heart catheterization (RHC) than those with normal RV function. A reduced 6-minute walk distance (6MWD) did not predict RV dysfunction (OR 0.995; 95% CI 0.980–1.001, p = 0.138). In addition, worsening restrictive physiology, heart rate at one-minute recovery and desaturation were not different between patients with and without RV dysfunction. However, there were inverse correlations between 6MWD and MPAP from RHC (r = -0.41, 
p = 0.010), 6MWD and RV systolic pressure (r = -0.51, p < 0.001), and 6MWD and MPAP measured by ECHO (r = -0.46, p =0.013). We also found no significant correlation between 6MWD and pulmonary function test parameters. Conclusions Our single-center cohort of patients with PH secondary to DPLD, PH was found to have an impact on 6MWD. In contrast to our expectations, 6MWD was not useful to predict RV dysfunction. Interestingly, a severe reduction in the 6MWD was related to PH and not to pulmonary function; therefore, it may be used to justify an ECHO to identify patients with a worse prognosis.

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

    NASA Technical Reports Server (NTRS)

    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.

  12. Pedometer Readings and Self-Reported Walking Distances in a Rural Hutterite Population

    ERIC Educational Resources Information Center

    Samra, Haifa Abou; Beare, Tianna; Specker, Bonny

    2008-01-01

    Purpose: This study assessed the accuracy with which a rural population reported daily walking distances using a 7-day activity recall questionnaire obtained quarterly compared to pedometer readings. Methods: Study participants were 48 Hutterite men and women aged 11-66 years. Findings: Pedometer-miles quartiles were associated with self-reported…

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

    SciTech Connect

    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.

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

    PubMed Central

    Sangelaji, Bahram; Kordi, Mohammadreza; Banihashemi, Farzaneh; Nabavi, Seyed Massood; Khodadadeh, Sara; Dastoorpoor, Maryam

    2016-01-01

    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. PMID:27648171

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

    PubMed Central

    Sangelaji, Bahram; Kordi, Mohammadreza; Banihashemi, Farzaneh; Nabavi, Seyed Massood; Khodadadeh, Sara; Dastoorpoor, Maryam

    2016-01-01

    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.

  16. [Effects of portable liquid oxygen therapy on walking].

    PubMed

    Arnedillo Muñoz, A; León Jiménez, A; Fernández Berni, J J; Córdoba Doña, J A; Rosano Romero, A

    1999-02-01

    The effect on walking of portable liquid oxygen therapy (PLOT), which involves carrying a tank, remains unclear. Our aim was to evaluate the repercussion of PLOT on performance in the 6 minute walking test. We enrolled 30 patients receiving home oxygen therapy in a randomized crossover study, collecting data on arterial blood gases at baseline, spirometry, and performance on the 6 minute walking test at baseline and at later sessions with PLOT and with compressed air simulating oxygen. During the tests we measured peak heart rate, distance walked and time that oxygen saturation remained over 89%. For compressed air, no improvement over baseline values was observed for any of the parameters measured. During the PLOT tests, however, patients walked farther than at baseline and arterial oxygen saturation rose to the prescribed flow rate. Dyspnea was not significantly affected.

  17. Reduced walking speed and distance as harbingers of the approaching grim reaper.

    PubMed

    Franklin, Barry A; Brinks, Jenna; Sacks, Roger; Trivax, Justin; Friedman, Harold

    2015-07-15

    Although treadmill exercise testing can provide an assessment of cardiorespiratory fitness, which serves as an independent prognostic indicator, numerous studies now suggest that usual gait speed, time, or distance covered during walk performance tests and weekly walking distance/time are powerful predictors of mortality and future cardiovascular events in selected patients. This review summarizes the relation between these variables and their association with cardiovascular and all-cause mortality, with specific reference to potential underlying mechanisms and implications for the clinician. Contemporary health care providers have escalating opportunities to promote lifestyle physical activity using pedometers, accelerometers, and smartphone-based health and wellness applications. In conclusion, fitness and/or ambulatory indexes should be considered a "vital sign" in middle-aged and older adults. PMID:25972052

  18. Locomotor Recovery in Spinal Cord Injury: Insights Beyond Walking Speed and Distance.

    PubMed

    Awai, Lea; Curt, Armin

    2016-08-01

    Recovery of locomotor function after incomplete spinal cord injury (iSCI) is clinically assessed through walking speed and distance, while improvements in these measures might not be in line with a normalization of gait quality and are, on their own, insensitive at revealing potential mechanisms underlying recovery. The objective of this study was to relate changes of gait parameters to the recovery of walking speed while distinguishing between parameters that rather reflect speed improvements from factors contributing to overall recovery. Kinematic data of 16 iSCI subjects were repeatedly recorded during in-patient rehabilitation. The responsiveness of gait parameters to walking speed was assessed by linear regression. Principal component analysis (PCA) was applied on the multivariate data across time to identify factors that contribute to recovery after iSCI. Parameters of gait cycle and movement dynamics were both responsive and closely related to the recovery of walking speed, which increased by 96%. Multivariate analysis revealed specific gait parameters (intralimb shape normality and consistency) that, although less related to speed increments, loaded highly on principal component one (PC1) (58.6%) explaining the highest proportion of variance (i.e., recovery of outcome over time). Interestingly, measures of hip, knee, and ankle range of motion showed varying degrees of responsiveness (from very high to very low) while not contributing to gait recovery as revealed by PCA. The conjunct application of two analysis methods distinguishes gait parameters that simply reflect increased walking speed from parameters that actually contribute to gait recovery in iSCI. This distinction may be of value for the evaluation of interventions for locomotor recovery.

  19. The six-minute walk distance is a marker of hemodynamic-related functional capacity in hypertension: a case-control study.

    PubMed

    Ramos, Rodrigo A; Guimarães, Fernando S; Cordovil, Ivan; de Sa Ferreira, Arthur

    2014-08-01

    This study investigated the association between hemodynamic variables and the 6-minute walk distance (6MWD) in adults with and without hypertension and explored the role of hemodynamic variables as predictors of 6MWD. Patients undergoing antihypertensive medication therapy (n=41) and sex-matched healthy subjects (n=41) were evaluated for their clinical status and cardiovascular risk factors. Two 6-minute walk tests were performed along an 18-m corridor with a 30-minute rest interval. The intraclass correlation (ICC) was high among patients (ICC=0.984 (0.965; 0.992), P<0.001) and controls (ICC=0.987 (0.832; 0.996), P<0.001). The patients presented 6MWD values that were significantly lower than those of healthy controls (338.8±112.8 vs. 388.0±66.7 m, P=0.010). In patients, the 6MWD was significantly and positively correlated with sex (0.737; P<0.001), height (0.502; P<0.001) and weight (0.303; P=0.027). In addition, negative and significant correlations were observed between 6MWD and the mean (-0.577; P<0.001), systolic (-0.521; P<0.001), diastolic (-0.505; P=0.001) and pulse (-0.353; P=0.015) pressures after simultaneous adjustment for age, body height and weight. The same behavior was observed in healthy controls (except for pulse pressure), albeit with lower correlation values. A regression model with sex, age, height and weight explained 52.2% (P<0.001) of the variance. The highest explained variance in patients (64.8%; P<0.001) and controls (56.5%; P<0.001) was observed after replacing the body weight with mean pressure in the model. The 6MWD is inversely associated with hemodynamic variables in both groups and is lower in patients with hypertension compared with healthy controls. Hemodynamic variables, particularly the mean pressure, should be included in prediction equations for 6MWD.

  20. The metabolic cost of changing walking speeds is significant, implies lower optimal speeds for shorter distances, and increases daily energy estimates

    PubMed Central

    Seethapathi, Nidhi; Srinivasan, Manoj

    2015-01-01

    Humans do not generally walk at constant speed, except perhaps on a treadmill. Normal walking involves starting, stopping and changing speeds, in addition to roughly steady locomotion. Here, we measure the metabolic energy cost of walking when changing speed. Subjects (healthy adults) walked with oscillating speeds on a constant-speed treadmill, alternating between walking slower and faster than the treadmill belt, moving back and forth in the laboratory frame. The metabolic rate for oscillating-speed walking was significantly higher than that for constant-speed walking (6–20% cost increase for ±0.13–0.27 m s−1 speed fluctuations). The metabolic rate increase was correlated with two models: a model based on kinetic energy fluctuations and an inverted pendulum walking model, optimized for oscillating-speed constraints. The cost of changing speeds may have behavioural implications: we predicted that the energy-optimal walking speed is lower for shorter distances. We measured preferred human walking speeds for different walking distances and found people preferred lower walking speeds for shorter distances as predicted. Further, analysing published daily walking-bout distributions, we estimate that the cost of changing speeds is 4–8% of daily walking energy budget. PMID:26382072

  1. Tactile and proprioceptive sensory stimulation modifies estimation of walking distance but not upright gait stability: a pilot study

    PubMed Central

    Paolucci, Teresa; Piccinini, Giulia; Paolucci, Stefano; Spadini, Ennio; Saraceni, Vincenzo Maria; Morone, Giovanni

    2015-01-01

    [Purpose] Recently, there has been growing interest in the somatosensory system, but little data exist on the interaction between dynamic postural control and the somatosensory system. The purpose of this study was to determine whether a training program, based on tactile and proprioceptive sensory stimulation of the trunk with the use of perceptual surfaces, improved the estimation of walking distance by healthy subjects, the ability to walk toward a memorized distance without vision, and whether it increases upright gait stability. [Subjects and Methods] Ten healthy subjects with a mean age of 31.9 ± 2.5 years were enrolled and participated in 10 daily sessions of perceptive training using perceptual surfaces, for 45 minutes each session. An experimental indoor test measured the subjects’ ability to perceive walking distances to a memorized target in an indoor environment. [Results] After treatment, the distances that were traversed were closer to the target than before treatment. Trunk acceleration did not differ significantly between pre- and post-training and did not increase significantly after training. [Conclusion] Treatment with perceptual surfaces stimulating the trunk midline improves the estimation of walking distance and modifies proprioceptive gait patterns, allowing various corrective strategies to be implemented during ambulation. PMID:26644695

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

    NASA Technical Reports Server (NTRS)

    Miller, Christopher A.; Feiveson, Al; Bloomberg, Jacob J.

    2007-01-01

    Toe trajectory during swing phase is a precise motor control task that can provide insights into the sensorimotor control of the legs. The purpose of this study was to determine changes in vertical toe trajectory during treadmill walking due to changes in walking speed and target distance. For each trial, subjects walked on a treadmill at one of five speeds while performing a dynamic visual acuity task at either a far or near target distance (five speeds two targets distances = ten trials). Toe clearance decreased with increasing speed, and the vertical toe peak just before heel strike increased with increasing speed, regardless of target distance. The vertical toe peak just after toe-off was lower during near-target visual acuity tasks than during far-target tasks, but was not affected by speed. The ankle of the swing leg appeared to be the main joint angle that significantly affected all three toe trajectory events. The foot angle of the swing leg significantly affected toe clearance and the toe peak just before heel strike. These results will be used to enhance the analysis of lower limb kinematics during the sensorimotor treadmill testing, where differing speeds and/or visual target distances may be used.

  3. Effect of 6-minute colonoscopy withdrawal time policy on polyp detection rate in a community hospital.

    PubMed

    Baker, Scott L; Miller, Roberta A; Creighton, Amy; Aguilar, Pedro S

    2015-01-01

    In 2002, a U.S. Multi-Society Task Force on colorectal cancer recommended a 6-minute or more withdrawal time as an indicator of a quality colonoscopy. In 2006, found a correlation between longer withdrawal time and an increased rate in the detection of adenomas. In January 2008, the endoscopy department at our institution adopted the Multi-Society Task Force recommendation. The aim of our study was to evaluate the effect of a minimal 6-minute withdrawal time policy at our institution on polyp detection rate. All colonoscopies performed for screening indications from April 2007 to September 2008 were reviewed retrospectively. Group I (pre-policy) was compared with Group II (post-policy). Data collected included age, gender, indication, polyp detection rate, size, and withdrawal time. Unpaired t tests evaluated pre- and postprocedure results. Fisher's exact tests were used to compare detection rates between withdrawal time less than 6 minutes and more than 6 minutes. Mann-Whitney U Tests were performed to analyze the significance between the number of polyps detected for withdrawal time less than 6 minutes versus more than 6 minutes. A total of 1,342 colonoscopies were available for analysis in Group I and 1,316 in Group II. Polyp detection rate was 46.6% in Group I versus 48.2% in Group II (p = .39), a non-statistically significant difference; however, there was a trend toward identifying small- and medium-sized polyps in Group II. Small polyps can carry a risk of severe dysplasia (). Data were then analyzed for withdrawal time. The polyp detection rate was 20.9 in procedures that took less than 6 minutes versus 48.3 in those that took more than 6 minutes (p ≤ .01). In this study, a 6-minute or more withdrawal time increased the polyp detection rate by 133% for all polyp sizes, especially small and medium. Small polyps (5 mm or less) should be removed and not ignored. A 6-minute or more withdrawal time should be mandatory in those patients without a previous colon

  4. Manipulation of visual information does not change the accuracy of distance estimation during a blindfolded walking task.

    PubMed

    Commins, Sean; McCormack, Kelsie; Callinan, Erin; Fitzgerald, Helen; Molloy, Eoin; Young, Kerrie

    2013-08-01

    While humans rely on vision during navigation, they are also competent at navigating non-visually. However, non-visual navigation over large distances is not very accurate and can accumulate error. Currently, it is unclear whether this accumulation of error is due to the visual estimate of the distance or to the locomotor production of the distance. In a series of experiments, using a blindfolded walking test, we examine whether enhancing the visual estimate of the distance to a previously seen target, through environmental enrichment, visual imagery, or repeated exposure would improve the accuracy of blindfold navigation across different distances. We also attempt to decrease the visual estimate in order to see if the opposite effect would occur. Our results would indicate that manipulation of the static visual distance estimate did not change the navigation accuracy to any great extent. The only condition that improved accuracy was repeated exposure to the environment through practice. These results suggest that error observed during blindfold navigation may be due to the locomotor production of the distance, rather than the visual process.

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

    PubMed

    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. PMID:27367214

  6. Revisiting the effect of quality of graphics on distance judgments in virtual environments: a comparison of verbal reports and blind walking.

    PubMed

    Kunz, Benjamin R; Wouters, Leah; Smith, Daniel; Thompson, William B; Creem-Regehr, Sarah H

    2009-08-01

    In immersive virtual environments, judgments of perceived egocentric distance are significantly underestimated, as compared with accurate performance in the real world. Two experiments assessed the influence of graphics quality on two distinct estimates of distance, a visually directed walking task and verbal reports. Experiment 1 demonstrated a similar underestimation of distances walked to previously viewed targets in both low- and high-quality virtual classrooms. In Experiment 2, participants' verbal judgments underestimated target distances in both graphics quality environments but were more accurate in the high-quality environment, consistent with the subjective impression that high-quality environments seem larger. Contrary to previous results, we suggest that quality of graphics does influence judgments of distance, but only for verbal reports. This behavioral dissociation has implications beyond the context of virtual environments and may reflect a differential use of cues and context for verbal reports and visually directed walking. PMID:19633344

  7. Six minute walk distance is a predictor of survival in patients with chronic obstructive pulmonary disease undergoing pulmonary rehabilitation

    PubMed Central

    Dajczman, Esther; Wardini, Rima; Kasymjanova, Goulnar; Préfontaine, David; Baltzan, Marc Alexander; Wolkove, Norman

    2015-01-01

    BACKGROUND: Chronic obstructive pulmonary disease (COPD) is a progressive and distressing disease with a trajectory that is often difficult to predict. OBJECTIVE: To determine whether initial 6 min walk distance (6MWD) or change in 6MWD following inpatient pulmonary rehabilitation (PR) predicted survival. METHODS: Patients referred for PR in 2010 were studied in a retrospective chart review. Measures of 6MWD before and following PR were recorded. Initial 6MWD was categorized as ≥250 m, 150 m to 249 m and ≤149 m. Government databases provided survival status up until December 2013 and survival analyses were performed. Initial 6MWD and a minimally important difference (MID) of ≥30 m were used for survival analysis. RESULTS: The cohort consisted of 237 patients (92 men, 145 women) with severe COPD. Mean (± SD) forced expiratory volume in 1 s (FEV1) was 0.75±0.36 L, with a mean FEV1/forced vital capacity (FVC) ratio of 0.57±0.16. Overall three-year survival was 58%. Mean survival for the study period as per predefined categories of 6MWD of ≥250 m, 150 m to 249 m and ≤149 m was 42.2, 37.0 and 27.8 months (P<0.001), respectively, with a three-year survival of 81%, 66% and 34% observed, respectively. Overall mean change in 6MWD was 62±57 m, and a minimal improvement of ≥30 m was observed in 72% of patients. In the lowest walking group, early mortality was significantly higher among those who did not achieve minimal improvement. Older age, male sex and shorter initial 6MWD were negative predictors of survival. CONCLUSION: In patients with severe COPD, initial 6MWD was predictive of survival. Overall survival at three years was only 58% and was especially poor (34%) in patients with low (<150 m) initial walk distance. PMID:26252533

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

    PubMed Central

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

    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; p<0.01). Accelerations for males and females were consistent throughout each backpack 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. PMID:24146708

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

    PubMed

    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.

  10. The Effect of Treadmill Exercise on Gait Efficiency During Overground Walking in Adults With Cerebral Palsy

    PubMed Central

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

    2015-01-01

    Objective 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. Methods 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. Results 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 (p<0.05). Energy efficiency evaluated by O2 cost during overground walking significantly improved from 0.56±0.36 to 0.41±0.18 mL/kg·m (p<0.05), whereas O2 rate did not improve significantly after the treadmill walking exercise. On the other hand, gait velocity and O2 cost during overground walking were not significantly changed in the control group. Conclusion 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. PMID:25750868

  11. Criterion-Related Validity of the Distance- and Time-Based Walk/Run Field Tests for Estimating Cardiorespiratory Fitness: A Systematic Review and Meta-Analysis

    PubMed Central

    Mayorga-Vega, Daniel; Bocanegra-Parrilla, Raúl; Ornelas, Martha; Viciana, Jesús

    2016-01-01

    Objectives The main purpose of the present meta-analysis was to examine the criterion-related validity of the distance- and time-based walk/run tests for estimating cardiorespiratory fitness among apparently healthy children and adults. Materials and Methods Relevant studies were searched from seven electronic bibliographic databases up to August 2015 and through other sources. The Hunter-Schmidt’s psychometric meta-analysis approach was conducted to estimate the population criterion-related validity of the following walk/run tests: 5,000 m, 3 miles, 2 miles, 3,000 m, 1.5 miles, 1 mile, 1,000 m, ½ mile, 600 m, 600 yd, ¼ mile, 15 min, 12 min, 9 min, and 6 min. Results From the 123 included studies, a total of 200 correlation values were analyzed. The overall results showed that the criterion-related validity of the walk/run tests for estimating maximum oxygen uptake ranged from low to moderate (rp = 0.42–0.79), with the 1.5 mile (rp = 0.79, 0.73–0.85) and 12 min walk/run tests (rp = 0.78, 0.72–0.83) having the higher criterion-related validity for distance- and time-based field tests, respectively. The present meta-analysis also showed that sex, age and maximum oxygen uptake level do not seem to affect the criterion-related validity of the walk/run tests. Conclusions When the evaluation of an individual’s maximum oxygen uptake attained during a laboratory test is not feasible, the 1.5 mile and 12 min walk/run tests represent useful alternatives for estimating cardiorespiratory fitness. As in the assessment with any physical fitness field test, evaluators must be aware that the performance score of the walk/run field tests is simply an estimation and not a direct measure of cardiorespiratory fitness. PMID:26987118

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

    PubMed Central

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

    2015-01-01

    Background: 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. Objective: 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. Methods: 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. Results: 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. Conclusion: 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. PMID:26364281

  13. Characteristics and determinants of endurance cycle ergometry and six-minute walk distance in patients with COPD

    PubMed Central

    2014-01-01

    Background Exercise tolerance can be assessed by the cycle endurance test (CET) and six-minute walk test (6MWT) in patients with Chronic Obstructive Pulmonary Disease (COPD). We sought to investigate the characteristics of functional exercise performance and determinants of the CET and 6MWT in a large clinical cohort of COPD patients. Methods A dataset of 2053 COPD patients (43% female, age: 66.9 ± 9.5 years, FEV1% predicted: 48.2 ± 23.2) was analyzed retrospectively. Patients underwent, amongst others, respiratory function evaluation; medical tests and questionnaires, one maximal incremental cycle test where peak work rate was determined and two functional exercise tests: a CET at 75% of peak work rate and 6MWT. A stepwise multiple linear regression was used to assess determinants. Results On average, patients had impaired exercise tolerance (peak work rate: 56 ± 27% predicted, 6MWT: 69 ± 17% predicted). A total of 2002 patients had CET time of duration (CET-Tend) less than 20 min while only 51 (2.5%) of the patients achieved 20 min of CET-Tend . In former patients, the percent of predicted peak work rate achieved differed significantly between men (48 ± 21% predicted) and women (67 ± 31% predicted). In contrast, CET-Tend was longer in men (286 ± 174 s vs 250 ± 153 s, p < 0.001). Also, six minute walking distance (6MWD) was higher in men compared to women, both in absolute terms as in percent of predicted (443 m, 67%predicted vs 431 m, 72%predicted, p < 0.05). Gender was associated with the CET-Tend but BMI, FEV1 and FRC were related to the 6MWD highlighting the different determinants of exercise performance between CET and 6MWT. Conclusions CET-Tend is a valuable outcome of CET as it is related to multiple clinical aspects of disease severity in COPD. Gender difference should temper the interpretation of CET. PMID:24885117

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

    PubMed

    Islam, M R; Garcia, S C; Clark, C E F; Kerrisk, K L

    2015-06-01

    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-based AMS

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

    PubMed Central

    Islam, M. R.; Garcia, S. C.; Clark, C. E. F.; Kerrisk, K. L.

    2015-01-01

    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-based AMS

  16. The reliability and validity of gait speed with different walking pace and distances against general health, physical function, and chronic disease in aged adults

    PubMed Central

    Kim, Hee-jae; Park, Ilhyoek; Lee, Hyo joo; Lee, On

    2016-01-01

    [Purpose] Gait speed is an important objective values associated with several health-related outcomes including functional mobility in aging people. However, walking test methodologies and descriptions are not standardized considering specific aims of research. This study examine the reliability and validity of gait speed measured at various distances and paces in elderly Koreans. [Methods] Fifty-four female participants ≥70 years of age were recruited from a local retirement community. Gait speed was assessed at 4, 6 and 10 meters, and at usual- and fast-pace walking mode. The short physical performance battery (SPPB) that estimates senior fitness includes three tests of lower-body function. Data concerning for the chronic conditions and self-perceived health of the participants was collected using questionnaires. Concurrent validity of gait speed using the aforementioned test protocols was determined by calculating the Pearson correlation coefficients. [Results] Significant positive correlations were evident between skeletal muscle mass and maximal pace walking regardless of distance (r=.301~.308; p<.05), but not with body fat. All gait tests significantly positively correlated with self-rated health (normal pace r=.328~.346, p<.05; maximal pace r=.427~.472, p<.001) and depression (normal pace r=.279~.430, p<.05; maximal pace r=.413~.456, p<.001). [Conclusion] Walking test at the normal pace appears suitable for estimating physical function and deterioration due to chronic disease. Walking test at a maximum pace might be useful for estimating subjective general health and skeletal muscle mass. PMID:27757387

  17. On the Anisotropy of Perceived Ground Extents and the Interpretation of Walked Distance as a Measure of Perception

    ERIC Educational Resources Information Center

    Li, Zhi; Sun, Emily; Strawser, Cassandra J.; Spiegel, Ariana; Klein, Brennan; Durgin, Frank H.

    2013-01-01

    Two experiments are reported concerning the perception of ground extent to discover whether prior reports of anisotropy between frontal extents and extents in depth were consistent across different measures (visual matching and pantomime walking) and test environments (outdoor environments and virtual environments). In Experiment 1 it was found…

  18. Patient Characteristics and Comorbidities Influence Walking Distances in Symptomatic Peripheral Arterial Disease: A Large One-Year Physiotherapy Cohort Study

    PubMed Central

    Dörenkamp, Sarah; Mesters, Ilse; van Breukelen, Gerard

    2016-01-01

    Objectives The aim of this study is to investigate the association between age, gender, body-mass index, smoking behavior, orthopedic comorbidity, neurologic comorbidity, cardiac comorbidity, vascular comorbidity, pulmonic comorbidity, internal comorbidity and Initial Claudication Distance during and after Supervised Exercise Therapy at 1, 3, 6 and 12 months in a large sample of patients with Intermittent Claudication. Methods Data was prospectively collected in standard physiotherapy care. Patients received Supervised Exercise Therapy according to the guideline Intermittent Claudication of the Royal Dutch Society for Physiotherapy. Three-level mixed linear regression analysis was carried out to analyze the association between patient characteristics, comorbidities and Initial Claudication Distance at 1, 3, 6 and 12 months. Results Data from 2995 patients was analyzed. Results showed that being female, advanced age and a high body-mass index were associated with lower Initial Claudication Distance at all-time points (p = 0.000). Besides, a negative association between cardiac comorbidity and Initial Claudication Distance was revealed (p = 0.011). The interaction time by age, time by body-mass index and time by vascular comorbidity were significantly associated with Initial Claudication Distance (p≤ 0.05). Per year increase in age (range: 33–93 years), the reduction in Initial Claudication Distance was 8m after 12 months of Supervised Exercise Therapy. One unit increase in body-mass index (range: 16–44 kg/m2) led to 10m less improvement in Initial Claudication Distance after 12 months and for vascular comorbidity the reduction in improvement was 85m after 12 months. Conclusions This study reveals that females, patients at advanced age, patients with a high body-mass index and cardiac comorbidity are more likely to show less improvement in Initial Claudication Distances (ICD) after 1, 3, 6 and 12 months of Supervised Exercise Therapy. Further research should

  19. Dynamic visual acuity (DVA) during locomotion for targets at near and far distances: effects of aging, walking speed and head-trunk coupling.

    PubMed

    Deshpande, Nandini; Tourtillott, Brandon M; Peters, Brian T; Bloomberg, Jacob J

    2013-01-01

    This study examined effects of aging, head-trunk coupling (HTcoupling) and walking speed on dynamic visual acuity (DVA) at near and far viewing distances. Ten healthy participants were recruited in 3 groups; young: 20-33 years, Older1: 65-74 years, Older2: 75-85 years. The binocular DVA was measured while walking on a treadmill at 0.75 and 1.5 m/s speeds. The optotype display was placed at 0.5 m for NearDVA and at 3.0 m for FarDVA. On randomly selected trials, HTcoupling was achieved by using a collar. A mix-factor ANOVA (age-group x HTcoupling x speed) was performed separately for the Near and FarDVA. NearDVA declined with HTcoupling (p=0.021). Additionally, NearDVA worsened at the faster speed (p< 0.001). At 1.5 m/s speed the differences between Young and Older2 groups were significant (p=0.012) and those between Older1 and Older2 were marginal (p=0.085). FarDVA declined at the faster speed (p< 0.001) with no effect of HTcoupling or age-group. NearDVA is more sensitive to normal aging process. These age-related deficits become more apparent at higher walking speeds. Effect of HTcoupling on NearDVA suggests a possible additive effect of insufficient dampening of the vertical movement of the overall head-trunk complex and inability of the linear vestibulo-ocular reflex to compensate for the consequent high discrepancy.

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

    PubMed

    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. PMID:27543478

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

    PubMed

    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.

  2. The J-Meter Coercivity Spectrometer - Hysteresis Loop, IRM Acquisition Spectrum and Viscosity Spectrum in 6 Minutes

    NASA Astrophysics Data System (ADS)

    Enkin, R. J.; Nourgaliev, D.; Iassonov, P.

    2009-05-01

    The J-Meter Coercivity Spectrometer uses an innovative robust design for measuring a geological sample's magnetic hysteresis loop, IRM acquisition spectrum and viscosity spectrum in 6 minutes. With this tool, several labs around the world have been able measure large sample collections and develop useful magnetic proxies for a variety of paleoclimate, diagenesis and other studies. The main element of the J-meter is a pulse magnetometer, in which an electromotive force pulse is induced in an array of pick-up coils by the magnetic field of a sample moving at a high speed past the coils. The sample is placed near the rim of a 50 cm diameter plexiglas disk which rotates 18 times a second through the pole pieces of an electromagnet. Both the induced and remanent magnetization are measured during each rotation of the disk. Induced magnetization for hysteresis loops are measure with a set of pick-up coils mounted directly on the pole pieces, similar to the geometry used for a vibrating sample magnetometer. The magnetic remanence is measured with a second array of coils situated away from the electromagnet and surrounded by a three-layer mu-metal shield. The electromagnet field is ramped up to 500 mT, and the down to the opposite polarity (-500 mT). The J meter is called a coercivity spectrometer because it is particularly well suited to measuring the IRM acquisition curve with sufficient sensitivity and resolution to take the derivative which defines the coercivity spectrum. To finish each measurement, the magnetic field is cut to zero and the viscous demagnetization is monitored for 100s, mostly following a log(time) relationship but with perturbations determined by the grain size distribution of the finest grains. A suite of analysis programs have been developed to determine hysteresis parameters and S-ratios, and to characterize coercivity and viscosity spectra. We present a series of applications demonstrating the power of the J-Meter to trace sediment sources

  3. Walking on Mars

    NASA Astrophysics Data System (ADS)

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

    1998-06-01

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

  4. Walking Problems

    MedlinePlus

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

  5. Walking the walk

    SciTech Connect

    Butler, B.

    1994-12-31

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

  6. Walking: technology and biology.

    PubMed

    Pfeiffer, Friedrich; Inoue, Hirochika

    2007-01-15

    If all the signs are to be believed, then the twenty-first century will technologically be characterized by machine walking and its relevant products, which possess all chances to become real bulk goods in the course of the next decades. With several university institutes and with Honda and Sony from the industrial side, Japan is today and without any doubt the leading nation in research and development of walking machines. The US and Europe follow at some distance. Walking machines will influence all areas of daily and industrial life and, with the fast evolution of artificial intelligence, will become a real partner of human beings. All relevant technologies are highly interdisciplinary, they will push the future technologies of all technical fields. The special issue on this topic gives a selection of walking machine research and development including some aspects from biology.

  7. Base Station Walk-Back

    NASA Video Gallery

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

  8. Randomized controlled trial of physical activity, cognition, and walking in multiple sclerosis.

    PubMed

    Sandroff, Brian M; Klaren, Rachel E; Pilutti, Lara A; Dlugonski, Deirdre; Benedict, Ralph H B; Motl, Robert W

    2014-02-01

    The present study adopted a randomized controlled trial design and examined the effect of a physical activity behavioral intervention on cognitive and walking performance among persons with MS who have mild or moderate disability status. A total of 82 MS patients were randomly allocated into intervention or wait-list control conditions. The intervention condition received a theory-based program for increasing physical activity behavior that was delivered via the Internet, and one-on-one video chat sessions with a behavior-change coach. Participants completed self-report measures of physical activity and disability status, and underwent the oral Symbol Digit Modalities Test (SDMT) and 6-minute walk (6MW) test before and after the 6-month period. Analysis using mixed-model ANOVA indicated a significant time × condition × disability group interaction on SDMT scores (p = 0.02, partial-η (2) = 0.08), such that persons with mild disability in the intervention condition demonstrated a clinically meaningful improvement in SDMT scores (~6 point change). There was a further significant time × condition interaction on 6MW distance (p = 0.02, partial-η (2) = 0.07), such that those in the intervention condition demonstrated an increase in 6MW distance relative to those in the control group. The current study supports physical activity as a promising tool for managing cognitive impairment and impaired walking performance in persons with MS, and suggests that physical activity might have specific effects on cognition and non-specific effects on walking performance in this population.

  9. A randomized controlled trial of telephone-mentoring with home-based walking preceding rehabilitation in COPD

    PubMed Central

    Cameron-Tucker, Helen Laura; Wood-Baker, Richard; Joseph, Lyn; Walters, Julia A; Schüz, Natalie; Walters, E Haydn

    2016-01-01

    Purpose With the limited reach of pulmonary rehabilitation (PR) and low levels of daily physical activity in chronic obstructive pulmonary disease (COPD), a need exists to increase daily exercise. This study evaluated telephone health-mentoring targeting home-based walking (tele-rehab) compared to usual waiting time (usual care) followed by group PR. Patients and methods People with COPD were randomized to tele-rehab (intervention) or usual care (controls). Tele-rehab delivered by trained nurse health-mentors supported participants’ home-based walking over 8–12 weeks. PR, delivered to both groups simultaneously, included 8 weeks of once-weekly education and self-management skills, with separate supervised exercise. Data were collected at three time-points: baseline (TP1), before (TP2), and after (TP3) PR. The primary outcome was change in physical capacity measured by 6-minute walk distance (6MWD) with two tests performed at each time-point. Secondary outcomes included changes in self-reported home-based walking, health-related quality of life, and health behaviors. Results Of 65 recruits, 25 withdrew before completing PR. Forty attended a median of 6 (4) education sessions. Seventeen attended supervised exercise (5±2 sessions). Between TP1 and TP2, there was a statistically significant increase in the median 6MWD of 12 (39.1) m in controls, but no change in the tele-rehab group. There were no significant changes in 6MWD between other time-points or groups, or significant change in any secondary outcomes. Participants attending supervised exercise showed a nonsignificant improvement in 6MWD, 12.3 (71) m, while others showed no change, 0 (33) m. The mean 6MWD was significantly greater, but not clinically meaningful, for the second test compared to the first at all time-points. Conclusion Telephone-mentoring for home-based walking demonstrated no benefit to exercise capacity. Two 6-minute walking tests at each time-point may not be necessary. Supervised exercise

  10. A randomized controlled trial of telephone-mentoring with home-based walking preceding rehabilitation in COPD

    PubMed Central

    Cameron-Tucker, Helen Laura; Wood-Baker, Richard; Joseph, Lyn; Walters, Julia A; Schüz, Natalie; Walters, E Haydn

    2016-01-01

    Purpose With the limited reach of pulmonary rehabilitation (PR) and low levels of daily physical activity in chronic obstructive pulmonary disease (COPD), a need exists to increase daily exercise. This study evaluated telephone health-mentoring targeting home-based walking (tele-rehab) compared to usual waiting time (usual care) followed by group PR. Patients and methods People with COPD were randomized to tele-rehab (intervention) or usual care (controls). Tele-rehab delivered by trained nurse health-mentors supported participants’ home-based walking over 8–12 weeks. PR, delivered to both groups simultaneously, included 8 weeks of once-weekly education and self-management skills, with separate supervised exercise. Data were collected at three time-points: baseline (TP1), before (TP2), and after (TP3) PR. The primary outcome was change in physical capacity measured by 6-minute walk distance (6MWD) with two tests performed at each time-point. Secondary outcomes included changes in self-reported home-based walking, health-related quality of life, and health behaviors. Results Of 65 recruits, 25 withdrew before completing PR. Forty attended a median of 6 (4) education sessions. Seventeen attended supervised exercise (5±2 sessions). Between TP1 and TP2, there was a statistically significant increase in the median 6MWD of 12 (39.1) m in controls, but no change in the tele-rehab group. There were no significant changes in 6MWD between other time-points or groups, or significant change in any secondary outcomes. Participants attending supervised exercise showed a nonsignificant improvement in 6MWD, 12.3 (71) m, while others showed no change, 0 (33) m. The mean 6MWD was significantly greater, but not clinically meaningful, for the second test compared to the first at all time-points. Conclusion Telephone-mentoring for home-based walking demonstrated no benefit to exercise capacity. Two 6-minute walking tests at each time-point may not be necessary. Supervised exercise

  11. Walking Perception by Walking Observers

    ERIC Educational Resources Information Center

    Jacobs, Alissa; Shiffrar, Maggie

    2005-01-01

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

  12. The six-minute walk--an adequate exercise test for pacemaker patients?

    PubMed

    Langenfeld, H; Schneider, B; Grimm, W; Beer, M; Knoche, M; Riegger, G; Kochsiek, K

    1990-12-01

    In many pacemaker patients bicycle and treadmill ergometry are not practicable. As an alternative, we performed a 6-minute walk on a 20-m corridor in 97 pacemaker patients, who were asked to walk as far as possible determining their speed by themselves. Results were compared with those of bicycle ergometry in 42 of these patients and with treadmill exercise of a group of 92 other pacemaker patients. In the 6-minute walk, performance and maximal heart rate were slightly lower (49 +/- 18 W; 96 +/- 23 beats/min) than in bicycle (57 +/- 16 W; 110 +/- 26 beats/min) and treadmill ergometry (50 +/- 37 W; 102 +/- 35 beats/min). A good correlation was found between walking and bicycling (r = 0.74) and in subgroups of patients with different pacemaker indications. All patients preferred the walk to bicycle ergometry considering it to be more related to daily physical activity. In conclusion, a 6-minute walk is a simple and physiological exercise test for nearly all pacemaker patients with good correlation to other types of exercise. It seems to be preferable to other tests because of its better acceptance and practicability. PMID:1704537

  13. Effect of a 4-week Nordic walking training on the physical fitness and self-assessment of the quality of health of women of the perimenopausal age

    PubMed Central

    Saulicz, Mariola; Saulicz, Edward; Myśliwiec, Andrzej; Wolny, Tomasz; Knapik, Andrzej; Rottermund, Jerzy

    2015-01-01

    Aim of the study To determine the effect of a 4-week Nordic walking training on the physical fitness of women of the perimenopausal age and self-assessment of the quality of their health. Material and methods Eighty-four women between 48 and 58 years of age were included in the study. Half of the group (42) was assigned to the control group and the other half was assigned to the experimental group. In both groups studied, physical fitness was evaluated using a modified Fullerton's test and a quality of life self-assessment SF-36 (Short Form of Health Status Questionnaire). Similar tests were repeated 4 weeks later. In the experimental group, a Nordic walking training was conducted between the two tests. During 4 weeks, 10 training sessions were performed, each session was 60 minutes long, and there was an interval of 2 days between the sessions. Results A 4-week Nordic walking training resulted in a significant improvement (p < 0.001) of physical fitness as demonstrated by an increased strength and flexibility of the upper and lower part of the body and the ability to walk a longer distance during a 6-minute walking test. Women participating in the training also showed a significant improvement in health in terms of both physical health (p < 0.001) and mental health (p < 0.001). Conclusions A 4-week Nordic walking training has a positive effect on the physical fitness of the women in the perimenopausal age. Participation in training contributes also to a clearly higher self-assessment of the quality of health. PMID:26327897

  14. Quantum random walks without walking

    SciTech Connect

    Manouchehri, K.; Wang, J. B.

    2009-12-15

    Quantum random walks have received much interest due to their nonintuitive dynamics, which may hold the key to a new generation of quantum algorithms. What remains a major challenge is a physical realization that is experimentally viable and not limited to special connectivity criteria. We present a scheme for walking on arbitrarily complex graphs, which can be realized using a variety of quantum systems such as a Bose-Einstein condensate trapped inside an optical lattice. This scheme is particularly elegant since the walker is not required to physically step between the nodes; only flipping coins is sufficient.

  15. Beam walking can detect differences in walking balance proficiency across a range of sensorimotor abilities.

    PubMed

    Sawers, Andrew; Ting, Lena H

    2015-02-01

    The ability to quantify differences in walking balance proficiency is critical to curbing the rising health and financial costs of falls. Current laboratory-based approaches typically focus on successful recovery of balance while clinical instruments often pose little difficulty for all but the most impaired patients. Rarely do they test motor behaviors of sufficient difficulty to evoke failures in balance control limiting their ability to quantify balance proficiency. Our objective was to test whether a simple beam-walking task could quantify differences in walking balance proficiency across a range of sensorimotor abilities. Ten experts, ten novices, and five individuals with transtibial limb loss performed six walking trials across three different width beams. Walking balance proficiency was quantified as the ratio of distance walked to total possible distance. Balance proficiency was not significantly different between cohorts on the wide-beam, but clear differences between cohorts on the mid and narrow-beams were identified. Experts walked a greater distance than novices on the mid-beam (average of 3.63±0.04m verus 2.70±0.21m out of 3.66m; p=0.009), and novices walked further than amputees (1.52±0.20m; p=0.03). Amputees were unable to walk on the narrow-beam, while experts walked further (3.07±0.14m) than novices (1.55±0.26m; p=0.0005). A simple beam-walking task and an easily collected measure of distance traveled detected differences in walking balance proficiency across sensorimotor abilities. This approach provides a means to safely study and evaluate successes and failures in walking balance in the clinic or lab. It may prove useful in identifying mechanisms underlying falls versus fall recoveries.

  16. A natural walking monitor for pulmonary patients using mobile phones.

    PubMed

    Juen, Joshua; Cheng, Qian; Schatz, Bruce

    2015-07-01

    Mobile devices have the potential to continuously monitor health by collecting movement data including walking speed during natural walking. Natural walking is walking without artificial speed constraints present in both treadmill and nurse-assisted walking. Fitness trackers have become popular which record steps taken and distance, typically using a fixed stride length. While useful for everyday purposes, medical monitoring requires precise accuracy and testing on real patients with a scientifically valid measure. Walking speed is closely linked to morbidity in patients and widely used for medical assessment via measured walking. The 6-min walk test (6MWT) is a standard assessment for chronic obstructive pulmonary disease and congestive heart failure. Current generation smartphone hardware contains similar sensor chips as in medical devices and popular fitness devices. We developed a middleware software, MoveSense, which runs on standalone smartphones while providing comparable readings to medical accelerometers. We evaluate six machine learning methods to obtain gait speed during natural walking training models to predict natural walking speed and distance during a 6MWT with 28 pulmonary patients and ten subjects without pulmonary condition. We also compare our model's accuracy to popular fitness devices. Our universally trained support vector machine models produce 6MWT distance with 3.23% error during a controlled 6MWT and 11.2% during natural free walking. Furthermore, our model attains 7.9% error when tested on five subjects for distance estimation compared to the 50-400% error seen in fitness devices during natural walking. PMID:25935052

  17. Sex-specific predictors of improved walking with step-monitored, home-based exercise in peripheral artery disease.

    PubMed

    Gardner, Andrew W; Parker, Donald E; Montgomery, Polly S

    2015-10-01

    The aim of this study was to determine whether baseline clinical characteristics and the duration and intensity of ambulation during our step-monitored home-based exercise program were predictive of changes in ambulatory outcomes at completion of the program in symptomatic patients with peripheral artery disease (PAD). Twenty-two men (ankle-brachial index (ABI) = 0.71 ± 0.19) and 24 women (ABI = 0.66 ± 0.23) completed the home exercise program, consisting of intermittent walking to mild-to-moderate claudication pain for 3 months. Ambulatory outcome measures were peak walking time (PWT) and claudication onset time (COT) during a treadmill test, and the distance recorded during a 6-minute walk distance test (6MWD). Men experienced significant increases (p<0.01) in COT, PWT, and 6MWD following the home exercise program, and women had significant increases in 6MWD (p<0.01) and PWT (p<0.05). In women, average exercise cadence during the home exercise sessions was the only predictor that entered the model for change in COT (p=0.082), and was the first predictor in the model for change in PWT (p=0.029) and 6MWD (p=0.006). In men, the ABI was the only predictor that entered the model for change in 6MWD (p=0.002), and ABI was a predictor along with metabolic syndrome in the model for change in COT (p=0.003). No variables entered the model for change in PWT. Faster ambulatory cadence during the step-monitored home-based exercise program may predict greater improvements in ambulatory function in women, whereas having less severe PAD and comorbid burden at baseline may predict greater improvements in ambulatory function in men. ClinicalTrials.gov Identifier: NCT00618670.

  18. Clinical effectiveness and safety of powered exoskeleton-assisted walking in patients with spinal cord injury: systematic review with meta-analysis

    PubMed Central

    Miller, Larry E; Zimmermann, Angela K; Herbert, William G

    2016-01-01

    Background Powered exoskeletons are designed to safely facilitate ambulation in patients with spinal cord injury (SCI). We conducted the first meta-analysis of the available published research on the clinical effectiveness and safety of powered exoskeletons in SCI patients. Methods MEDLINE and EMBASE databases were searched for studies of powered exoskeleton-assisted walking in patients with SCI. Main outcomes were analyzed using fixed and random effects meta-analysis models. Results A total of 14 studies (eight ReWalk™, three Ekso™, two Indego®, and one unspecified exoskeleton) representing 111 patients were included in the analysis. Training programs were typically conducted three times per week, 60–120 minutes per session, for 1–24 weeks. Ten studies utilized flat indoor surfaces for training and four studies incorporated complex training, including walking outdoors, navigating obstacles, climbing and descending stairs, and performing activities of daily living. Following the exoskeleton training program, 76% of patients were able to ambulate with no physical assistance. The weighted mean distance for the 6-minute walk test was 98 m. The physiologic demand of powered exoskeleton-assisted walking was 3.3 metabolic equivalents and rating of perceived exertion was 10 on the Borg 6–20 scale, comparable to self-reported exertion of an able-bodied person walking at 3 miles per hour. Improvements in spasticity and bowel movement regularity were reported in 38% and 61% of patients, respectively. No serious adverse events occurred. The incidence of fall at any time during training was 4.4%, all occurring while tethered using a first-generation exoskeleton and none resulting in injury. The incidence of bone fracture during training was 3.4%. These risks have since been mitigated with newer generation exoskeletons and refinements to patient eligibility criteria. Conclusion Powered exoskeletons allow patients with SCI to safely ambulate in real-world settings at

  19. Cell phones change the way we walk.

    PubMed

    Lamberg, Eric M; Muratori, Lisa M

    2012-04-01

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

  20. Oral Chinese herbal medicine combined with pharmacotherapy for stable COPD: a systematic review of effect on BODE index and six minute walk test.

    PubMed

    Chen, Xiankun; May, Brian; Di, Yuan Ming; Zhang, Anthony Lin; Lu, Chuanjian; Xue, Charlie Changli; Lin, Lin

    2014-01-01

    This systematic review evaluated the effects of Chinese herbal medicine (CHM) plus routine pharmacotherapy (RP) on the objective outcome measures BODE index, 6-minute walk test (6MWT), and 6-minute walk distance (6MWD) in individuals with stable chronic obstructive pulmonary disease (COPD). Searches were conducted of six English and Chinese databases (PubMed, EMBASE, CENTRAL, CINAHL, CNKI and CQVIP) from their inceptions until 18th November 2013 for randomized controlled trials involving oral administration of CHM plus RP compared to the same RP, with BODE Index and/or 6MWT/D as outcomes. Twenty-five studies were identified. BODE Index was used in nine studies and 6MWT/D was used in 22 studies. Methodological quality was assessed using the Cochrane Risk of Bias tool. Weaknesses were identified in most studies. Six studies were judged as 'low' risk of bias for randomisation sequence generation. Twenty-two studies involving 1,834 participants were included in the meta-analyses. The main meta-analysis results showed relative benefits for BODE Index in nine studies (mean difference [MD] -0.71, 95% confidence interval [CI] -0.94, -0.47) and 6MWT/D in 17 studies (MD 54.61 meters, 95%CI 33.30, 75.92) in favour of the CHM plus RP groups. The principal plants used were Astragalus membranaceus, Panax ginseng and Cordyceps sinensis. A. membranaceus was used in combination with other herbs in 18 formulae in 16 studies. Detailed sub-group and sensitivity analyses were conducted. Clinically meaningful benefits for BODE Index and 6MWT were found in multiple studies. These therapeutic effects were promising but need to be interpreted with caution due to variations in the CHMs and RPs used and methodological weakness in the studies. These issues should be addressed in future trials. PMID:24622390

  1. Walking molecules.

    PubMed

    von Delius, Max; Leigh, David A

    2011-07-01

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

  2. Random walk near the surface

    NASA Astrophysics Data System (ADS)

    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.

  3. Complementarity and quantum walks

    SciTech Connect

    Kendon, Viv; Sanders, Barry C.

    2005-02-01

    We show that quantum walks interpolate between a coherent 'wave walk' and a random walk depending on how strongly the walker's coin state is measured; i.e., the quantum walk exhibits the quintessentially quantum property of complementarity, which is manifested as a tradeoff between knowledge of which path the walker takes vs the sharpness of the interference pattern. A physical implementation of a quantum walk (the quantum quincunx) should thus have an identifiable walker and the capacity to demonstrate the interpolation between wave walk and random walk depending on the strength of measurement.

  4. Fire-Walking

    ERIC Educational Resources Information Center

    Willey, David

    2010-01-01

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

  5. Walking Capacity of Bariatric Surgery Candidates

    PubMed Central

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

    2011-01-01

    Background This study characterizes the walking limitations of bariatric surgery candidates by age and body mass index (BMI) and determines factors independently associated with walking capacity. Setting Multi-institutional at research university hospitals in the United States. Methods 2458 participants of the Longitudinal Assessment of Bariatric Surgery study (age: 18-78 y, BMI: 33-94 kg/m2) attended a pre-operative research visit. Walking capacity was measured via self-report and the 400 meter Long Distance Corridor Walk (LDCW). Results Almost two-thirds (64%) of subjects reported limitations walking several blocks, 48% had an objectively-defined mobility deficit, and 16% reported at least some walking aid use. In multivariable analysis, BMI, older age, lower income and greater bodily pain were independently associated (p<.05) with walking aid use, physical discomfort during the LDCW, inability to complete the LDCW, and slower time to complete the LDCW. Female sex, Hispanic ethnicity (but not race), higher resting heart rate, history of smoking, several comoribidities (history of stroke, ischemic heart disease, diabetes, asthma, sleep apnea, venous edema with ulcerations), and depressive symptoms were also independently related (p<.05) to at least one measure of reduced walking capacity. Conclusions Walking limitations are common in bariatric surgery candidates, even among the least severely obese and youngest patients. Physical activity counseling must be tailored to individuals' abilities. While several factors identified in this study (e.g., BMI, age, pain, comorbidities) should be considered, directly assessing walking capacity will facilitate appropriate goal-setting. PMID:21937285

  6. Walk This Way

    ERIC Educational Resources Information Center

    Mason, Nick

    2007-01-01

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

  7. Walking Wellness. Student Workbook.

    ERIC Educational Resources Information Center

    Sweetgall, Robert; Neeves, Robert

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

  8. Quantum walk computation

    SciTech Connect

    Kendon, Viv

    2014-12-04

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

  9. Factors influencing whether children walk to school.

    PubMed

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

    2013-07-01

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

  10. Factors Influencing Whether Children Walk to School

    PubMed Central

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

    2015-01-01

    Few studies have evaluated multiple levels of influence simultaneously on whether children walk to school. A large cohort of 4,338 subjects from ten communities was used to identify the determinants of walking through (1) a one-level logistic regression model for individual-level variables and (2) a two-level mixed regression model for individual and school-level variables. Walking rates were positively associated with home-to-school proximity, greater age, and living in neighborhoods characterized by lower traffic density. Greater land use mix around the home was, however, associated with lower rates of walking. Rates of walking to school were also higher amongst recipients of the Free and Reduced Price Meals Program and attendees of schools with higher percentage of English language learners. Designing schools in the same neighborhood as residential districts should be an essential urban planning strategy to reduce walking distance to school. Policy interventions are needed to encourage children from higher socioeconomic status families to participate in active travel to school and to develop walking infrastructures and other measures that protect disadvantaged children. PMID:23707968

  11. Healthy Living Initiative: Running/Walking Club

    ERIC Educational Resources Information Center

    Stylianou, Michalis; Kulinna, Pamela Hodges; Kloeppel, Tiffany

    2014-01-01

    This study was grounded in the public health literature and the call for schools to serve as physical activity intervention sites. Its purpose was twofold: (a) to examine the daily distance covered by students in a before-school running/walking club throughout 1 school year and (b) to gain insights on the teachers perspectives of the club.…

  12. Assessment of a Solar System Walk

    ERIC Educational Resources Information Center

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

    2010-01-01

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

  13. Constrained optimization in human walking: cost minimization and gait plasticity.

    PubMed

    Bertram, John E A

    2005-03-01

    As walking speed increases, consistent relationships emerge between the three determinant parameters of walking, speed, step frequency and step length. However, when step length or step frequency are predetermined rather than speed, different relationships are spontaneously selected. This result is expected if walking parameters are selected to optimize to an underlying objective function, known as the constrained optimization hypothesis. The most likely candidate for the objective function is metabolic cost per distance traveled, where the hypothesis predicts that the subject will minimize the cost of travel under a given gait constraint even if this requires an unusual step length and frequency combination. In the current study this is tested directly by measuring the walking behavior of subjects constrained systematically to determined speeds, step frequencies or step lengths and comparing behavior to predictions derived directly from minimization of measured metabolic cost. A metabolic cost surface in speed-frequency space is derived from metabolic rate for 10 subjects walking at 49 speed-frequency conditions. Optimization is predicted from the iso-energetic cost contours derived from this surface. Substantial congruence is found between the predicted and observed behavior using the cost of walking per unit distance. Although minimization of cost per distance appears to dominate walking control, certain notable differences from predicted behavior suggest that other factors must also be considered. The results of these studies provide a new perspective on the integration of walking cost with neuromuscular control, and provide a novel approach to the investigation of the control features involved in gait parameter selection.

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

    ERIC Educational Resources Information Center

    Sweetgall, Robert; Neeves, Robert

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

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

    PubMed Central

    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

  16. Walking boot assembly

    NASA Technical Reports Server (NTRS)

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

    1977-01-01

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

  17. Anyonic quantum walks

    SciTech Connect

    Brennen, Gavin K.; Ellinas, Demosthenes; Kendon, Viv; Pachos, Jiannis K. Tsohantjis, Ioannis; Wang Zhenghan

    2010-03-15

    The one dimensional quantum walk of anyonic systems is presented. The anyonic walker performs braiding operations with stationary anyons of the same type ordered canonically on the line of the walk. Abelian as well as non-Abelian anyons are studied and it is shown that they have very different properties. Abelian anyonic walks demonstrate the expected quadratic quantum speedup. Non-Abelian anyonic walks are much more subtle. The exponential increase of the system's Hilbert space and the particular statistical evolution of non-Abelian anyons give a variety of new behaviors. The position distribution of the walker is related to Jones polynomials, topological invariants of the links created by the anyonic world-lines during the walk. Several examples such as the SU(2){sub k} and the quantum double models are considered that provide insight to the rich diffusion properties of anyons.

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

    NASA Astrophysics Data System (ADS)

    Srinivasan, Manoj

    2009-06-01

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

  19. More than just perception-action recalibration: walking through a virtual environment causes rescaling of perceived space.

    PubMed

    Kelly, Jonathan W; Donaldson, Lisa S; Sjolund, Lori A; Freiberg, Jacob B

    2013-10-01

    Egocentric distances in virtual environments are commonly underperceived by up to 50 % of the intended distance. However, a brief period of interaction in which participants walk through the virtual environment while receiving visual feedback can dramatically improve distance judgments. Two experiments were designed to explore whether the increase in postinteraction distance judgments is due to perception-action recalibration or the rescaling of perceived space. Perception-action recalibration as a result of walking interaction should only affect action-specific distance judgments, whereas rescaling of perceived space should affect all distance judgments based on the rescaled percept. Participants made blind-walking distance judgments and verbal size judgments in response to objects in a virtual environment before and after interacting with the environment through either walking (Experiment 1) or reaching (Experiment 2). Size judgments were used to infer perceived distance under the assumption of size-distance invariance, and these served as an implicit measure of perceived distance. Preinteraction walking and size-based distance judgments indicated an underperception of egocentric distance, whereas postinteraction walking and size-based distance judgments both increased as a result of the walking interaction, indicating that walking through the virtual environment with continuous visual feedback caused rescaling of the perceived space. However, interaction with the virtual environment through reaching had no effect on either type of distance judgment, indicating that physical translation through the virtual environment may be necessary for a rescaling of perceived space. Furthermore, the size-based distance and walking distance judgments were highly correlated, even across changes in perceived distance, providing support for the size-distance invariance hypothesis. PMID:23839015

  20. More than just perception-action recalibration: walking through a virtual environment causes rescaling of perceived space.

    PubMed

    Kelly, Jonathan W; Donaldson, Lisa S; Sjolund, Lori A; Freiberg, Jacob B

    2013-10-01

    Egocentric distances in virtual environments are commonly underperceived by up to 50 % of the intended distance. However, a brief period of interaction in which participants walk through the virtual environment while receiving visual feedback can dramatically improve distance judgments. Two experiments were designed to explore whether the increase in postinteraction distance judgments is due to perception-action recalibration or the rescaling of perceived space. Perception-action recalibration as a result of walking interaction should only affect action-specific distance judgments, whereas rescaling of perceived space should affect all distance judgments based on the rescaled percept. Participants made blind-walking distance judgments and verbal size judgments in response to objects in a virtual environment before and after interacting with the environment through either walking (Experiment 1) or reaching (Experiment 2). Size judgments were used to infer perceived distance under the assumption of size-distance invariance, and these served as an implicit measure of perceived distance. Preinteraction walking and size-based distance judgments indicated an underperception of egocentric distance, whereas postinteraction walking and size-based distance judgments both increased as a result of the walking interaction, indicating that walking through the virtual environment with continuous visual feedback caused rescaling of the perceived space. However, interaction with the virtual environment through reaching had no effect on either type of distance judgment, indicating that physical translation through the virtual environment may be necessary for a rescaling of perceived space. Furthermore, the size-based distance and walking distance judgments were highly correlated, even across changes in perceived distance, providing support for the size-distance invariance hypothesis.

  1. Walking Humanoid Robot Lola

    NASA Astrophysics Data System (ADS)

    Schwienbacher, Markus; Favot, Valerio; Buschmann, Thomas; Lohmeier, Sebastian; Ulbrich, Heinz

    Based on the experience gathered from the walking robot Johnnie the new performance enhanced 25-DoF humanoid robot Lola was built. The goal of this project is to realize a fast, human-like walking. This paper presents different aspects of this complex mechatronic system. Besides the overall lightweight construction, custom build multi-sensory joint drives with high torque brush-less motors were crucial for reaching the performance goal. A decentralized electronics architecture is used for joint control and sensor data processing. A simulation environment serves as a testbed for the walking control, to minimize the risk of damaging the robot hardware during real world experiments.

  2. Simulation Distances

    NASA Astrophysics Data System (ADS)

    Černý, Pavol; Henzinger, Thomas A.; Radhakrishna, Arjun

    Boolean notions of correctness are formalized by preorders on systems. Quantitative measures of correctness can be formalized by real-valued distance functions between systems, where the distance between implementation and specification provides a measure of "fit" or "desirability." We extend the simulation preorder to the quantitative setting, by making each player of a simulation game pay a certain price for her choices. We use the resulting games with quantitative objectives to define three different simulation distances. The correctness distance measures how much the specification must be changed in order to be satisfied by the implementation. The coverage distance measures how much the implementation restricts the degrees of freedom offered by the specification. The robustness distance measures how much a system can deviate from the implementation description without violating the specification. We consider these distances for safety as well as liveness specifications. The distances can be computed in polynomial time for safety specifications, and for liveness specifications given by weak fairness constraints. We show that the distance functions satisfy the triangle inequality, that the distance between two systems does not increase under parallel composition with a third system, and that the distance between two systems can be bounded from above and below by distances between abstractions of the two systems. These properties suggest that our simulation distances provide an appropriate basis for a quantitative theory of discrete systems. We also demonstrate how the robustness distance can be used to measure how many transmission errors are tolerated by error correcting codes.

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

    PubMed

    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. When Human Walking is a Random Walk

    NASA Astrophysics Data System (ADS)

    Hausdorff, J. M.

    1998-03-01

    The complex, hierarchical locomotor system normally does a remarkable job of controlling an inherently unstable, multi-joint system. Nevertheless, the stride interval --- the duration of a gait cycle --- fluctuates from one stride to the next, even under stationary conditions. We used random walk analysis to study the dynamical properties of these fluctuations under normal conditions and how they change with disease and aging. Random walk analysis of the stride-to-stride fluctuations of healthy, young adult men surprisingly reveals a self-similar pattern: fluctuations at one time scale are statistically similar to those at multiple other time scales (Hausdorff et al, J Appl Phsyiol, 1995). To study the stability of this fractal property, we analyzed data obtained from healthy subjects who walked for 1 hour at their usual pace, as well as at slower and faster speeds. The stride interval fluctuations exhibited long-range correlations with power-law decay for up to a thousand strides at all three walking rates. In contrast, during metronomically-paced walking, these long-range correlations disappeared; variations in the stride interval were uncorrelated and non-fractal (Hausdorff et al, J Appl Phsyiol, 1996). To gain insight into the mechanism(s) responsible for this fractal property, we examined the effects of aging and neurological impairment. Using detrended fluctuation analysis (DFA), we computed 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

  5. Idiopathic toe walking.

    PubMed

    Oetgen, Matthew E; Peden, Sean

    2012-05-01

    Toe walking is a bilateral gait abnormality in which a normal heel strike is absent and most weight bearing occurs through the forefoot. This abnormality may not be pathologic in patients aged <2 years, but it is a common reason for referral to an orthopaedic surgeon. Toe walking can be caused by several neurologic and developmental abnormalities and may be the first sign of a global developmental problem. Cases that lack a definitive etiology are categorized as idiopathic. A detailed history, with careful documentation of the developmental history, and a thorough physical examination are required in the child with a primary report of toe walking. Treatment is based on age and the severity of the abnormality. Management includes observation, stretching, casting, bracing, chemodenervation, and surgical lengthening of the gastrocnemius-soleus complex and/or Achilles tendon. An understanding of idiopathic toe walking as well as treatment options and their outcomes can help the physician individualize treatment to achieve optimal results.

  6. Forces and pressures in adsorbing partially directed walks

    NASA Astrophysics Data System (ADS)

    Janse van Rensburg, E. J.; Prellberg, T.

    2016-05-01

    Polymers in confined spaces lose conformational entropy. This induces a net repulsive entropic force on the walls of the confining space. A model for this phenomenon is a lattice walk between confining walls, and in this paper a model of an adsorbing partially directed walk is used. The walk is placed in a half square lattice {{{L}}}+2 with boundary \\partial {{{L}}}+2, and confined between two vertical parallel walls, which are vertical lines in the lattice, a distance w apart. The free energy of the walk is determined, as a function of w, for walks with endpoints in the confining walls and adsorbing in \\partial {{{L}}}+2. This gives the entropic force on the confining walls as a function of w. It is shown that there are zero force points in this model and the locations of these points are determined, in some cases exactly, and in other cases asymptotically.

  7. Distance Education.

    ERIC Educational Resources Information Center

    ASPBAE Courier, 1984

    1984-01-01

    This publication is devoted to distance education. "The Future of Distance Teaching Universities in a Worldwide Perspectives" (John S. Daniel) examines challenges likely to face the various countries and regions of the world in the next decade. "An Australian University's Approach to Distance Education--Formal and Non-Formal" (Peter M. Grayson)…

  8. The melting phenomenon in random-walk model of DNA

    SciTech Connect

    Hayrapetyan, G. N.; Mamasakhlisov, E. Sh.; Papoyan, Vl. V.; Poghosyan, S. S.

    2012-10-15

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

  9. D.U.C.K. Walking.

    ERIC Educational Resources Information Center

    Steller, Jenifer J.

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

  10. Mechanics of competition walking.

    PubMed

    Cavagna, G A; Franzetti, P

    1981-06-01

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

  11. Walking and Proximity to the Urban Growth Boundary and Central Business District

    PubMed Central

    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

    2014-01-01

    Background 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. Purpose 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. Methods 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 each UDB- and CBD-distance 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. Results 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. Conclusions 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. PMID:24975010

  12. Walks on SPR neighborhoods.

    PubMed

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

    2013-01-01

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

  13. Walks on SPR neighborhoods.

    PubMed

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

    2013-01-01

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

  14. From Walking to Running

    NASA Astrophysics Data System (ADS)

    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.

  15. Random walks on networks

    NASA Astrophysics Data System (ADS)

    Donnelly, Isaac

    Random walks on lattices are a well used model for diffusion on continuum. They have been to model subdiffusive systems, systems with forcing and reactions as well as a combination of the three. We extend the traditional random walk framework to the network to obtain novel results. As an example due to the small graph diameter, the early time behaviour of subdiffusive dynamics dominates the observed system which has implications for models of the brain or airline networks. I would like to thank the Australian American Fulbright Association.

  16. Evaluating walking in patients with multiple sclerosis: which assessment tools are useful in clinical practice?

    PubMed

    Bethoux, Francois; Bennett, Susan

    2011-01-01

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

  17. Too far to walk or bike?

    PubMed

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

    2013-01-01

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

  18. Too far to walk or bike?

    PubMed

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

    2013-01-01

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

  19. Walking simulator for evaluation of ophthalmic devices

    NASA Astrophysics Data System (ADS)

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

    2005-03-01

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

  20. Asymptotic properties of a bold random walk

    NASA Astrophysics Data System (ADS)

    Serva, Maurizio

    2014-08-01

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

  1. Walking in My Shoes

    ERIC Educational Resources Information Center

    Salia, Hannah

    2010-01-01

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

  2. Walking On Air

    NASA Video Gallery

    This video features a series of time lapse sequences photographed by the Expedition 30 crew aboard the International Space Station. Set to the song “Walking in the Air,” by Howard Blake, the v...

  3. A Walk through Time.

    ERIC Educational Resources Information Center

    Renfroe, Mark; Letendre, Wanda

    1996-01-01

    Describes a seventh-grade class project where students constructed a "time tunnel" (a walk-through display with models and exhibits illustrating various themes and eras). Beginning modestly, the tunnel grew over seven years to include 11 different display scenes. Discusses the construction of the project and benefits to the school. (MJP)

  4. Walking Out Graphs

    ERIC Educational Resources Information Center

    Shen, Ji

    2009-01-01

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

  5. Deterministic Walks with Choice

    SciTech Connect

    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.

  6. Take a Planet Walk

    ERIC Educational Resources Information Center

    Schuster, Dwight

    2008-01-01

    Physical models in the classroom "cannot be expected to represent the full-scale phenomenon with complete accuracy, not even in the limited set of characteristics being studied" (AAAS 1990). Therefore, by modifying a popular classroom activity called a "planet walk," teachers can explore upper elementary students' current understandings; create an…

  7. The Longest Walk.

    ERIC Educational Resources Information Center

    American Indian Journal, 1978

    1978-01-01

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

  8. The walking robot project

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

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

  9. How to walk a conveyor

    SciTech Connect

    2007-06-15

    The article gives a check list of what one should know before walking a belt conveyor, and what to do during the walk. It then presents a list of what to look at on a walk along the conveyor system (excluding related equipment which could be inspected or maintained during the walk). It gives advice on when to stop the conveyor, on testing the emergency stop system, on recording problems and on acting on things noted. 1 tab.

  10. Walking with a Slower Friend

    ERIC Educational Resources Information Center

    Bailey, Herb; Kalman, Dan

    2011-01-01

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

  11. The shuttle walk exercise test in idiopathic pulmonary fibrosis.

    PubMed

    Moloney, E D; Clayton, N; Mukherjee, D K; Gallagher, C G; Egan, J J

    2003-06-01

    The shuttle walk test (SWT) is a validated, incremental walking test for chronic obstructive pulmonary disease, but not for idiopathic pulmonary fibrosis (IPF). The measurement of maximal oxygen consumption (VO2 max) is considered to be the gold standard measurement of functional capacity. This study examines the relationship between IPF patients' performance on the SWT and VO2 max. Twenty patients were recruited for the study, which consisted of two separate experiments. Firstly, the relationship between SWT performance on a conventional corridor SWT, with that on a programmable treadmill SWT designed to reproduce the corridor SWT was examined (n=10). In the second experiment, the relationship between performance on the treadmill equivalent SWT and VO2 max measurements was studied (n=10). There was a significant correlation between distance walked on the corridor SWT, and that walked on the treadmill equivalent SWT without VO2 max measurements (367 m vs. 410 m) (r=0.91, P=0.0003). There was a significant correlation between distance walked on the treadmill equivalent SWT (277 m), and the directly determined VO2 max (14.87 ml/kg/min) (r=0.74, P=0.01). During both experiments, a significant correlation was also observed between baseline PaO2 and SWT performance, and between DLCO and SWT performance. The shuttle walk test is a simple objective measure of functional capacity in IPF patients, which should facilitate the evaluation of new therapeutic compounds for IPF.

  12. Gait Evaluation of Overground Walking and Treadmill Walking Using Compass-Type Walking Model

    NASA Astrophysics Data System (ADS)

    Nagata, Yousuke; Yamamoto, Masayoshi; Funabiki, Shigeyuki

    A treadmill is a useful apparatus for the gait training and evaluation. However, many differences are reported between treadmill and overground walking. Experimental comparisons of the muscle activity of the leg and the heart rate have been carried out. However, the dynamic comparison has not been performed. The dynamic evaluation of the overground walking and the treadmill walking using a compass-type walking model (CTWM) which is a simple bipedal walking model, then their comparison is discussed. It is confirmed that the walking simulation using the CTWM can simulate the difference of that walk, it is clarified that there are the differences of the kick impulse on the ground and the turning impulse of the foot to the variation of the belt speed and then differences are the main factor of two walking.

  13. Nutrition for distance events.

    PubMed

    Burke, Louise M; Millet, Gregoire; Tarnopolsky, Mark A

    2007-01-01

    The goal of training is to prepare the distance athlete to perform at his or her best during major competitions. Whatever the event, nutrition plays a major role in the achievement of various factors that will see a runner or walker take the starting line in the best possible form. Everyday eating patterns must supply fuel and nutrients needed to optimize their performance during training sessions and to recover quickly afterwards. Carbohydrate and fluid intake before, during, and after a workout may help to reduce fatigue and enhance performance. Recovery eating should also consider issues for adaptation and the immune system that may involve intakes of protein and some micronutrients. Race preparation strategies should include preparation of adequate fuel stores, including carbohydrate loading for prolonged events such as the marathon or 50-km walk. Fluid and carbohydrate intake during races lasting an hour or more should also be considered. Sports foods and supplements of value to distance athletes include sports drinks and liquid meal supplements to allow nutrition goals to be achieved when normal foods are not practical. While caffeine is an ergogenic aid of possible value to distance athletes, most other supplements are of minimal benefit. PMID:18049981

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

    PubMed

    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.

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

    PubMed Central

    2012-01-01

    Background Using two different measures of park area, at three buffer distances, we sought to investigate the ways in which park area and proximity to parks, are related to the frequency of walking (for all purposes) in Australian adults. Little previous research has been conducted in this area, and results of existing research have been mixed. Methods Residents of 50 urban areas in metropolitan Melbourne, Australia completed a physical activity survey (n = 2305). Respondents reported how often they walked for ≥10 minutes in the previous month. Walking frequency was dichotomised to ‘less than weekly’ (less than 1/week) and ‘at least weekly’ (1/week or more). Using Geographic Information Systems, Euclidean buffers were created around each respondent’s home at three distances: 400metres (m), 800 m and 1200 m. Total area of parkland in each person’s buffer was calculated for the three buffers. Additionally, total area of ‘larger parks’, (park space ≥ park with Australian Rules Football oval (17,862 m2)), was calculated for each set of buffers. Area of park was categorised into tertiles for area of all parks, and area of larger parks (the lowest tertile was used as the reference category). Multilevel logistic regression, with individuals nested within areas, was used to estimate the effect of area of parkland on walking frequency. Results No statistically significant associations were found between walking frequency and park area (total and large parks) within 400 m of respondent’s homes. For total park area within 800 m, the odds of walking at least weekly were lower for those in the mid (OR 0.65, 95% CI 0.46-0.91) and highest (OR 0.65, 95% CI 0.44-0.95) tertile of park area compared to those living in areas with the least amount of park area. Similar results were observed for total park area in the 1200 m buffers. When only larger parks were investigated, again more frequent walking was less likely when respondents had access to a greater

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

    PubMed

    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.

  17. [Walking abnormalities in children].

    PubMed

    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

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

    PubMed

    Hanley, Brian; Bissas, Athanassios; Drake, Andrew

    2013-01-01

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

  19. Relativistic Weierstrass random walks.

    PubMed

    Saa, Alberto; Venegeroles, Roberto

    2010-08-01

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

  20. The Walking Droplet Instability

    NASA Astrophysics Data System (ADS)

    Bostwick, Joshua; Steen, Paul

    2013-11-01

    A droplet of liquid that partially wets a solid substrate assumes a spherical-cap equilibrium shape. We show that the spherical-cap with a mobile contact-line is unstable to a non-axisymmetric disturbance and we characterize the instability mechanism, as it depends upon the wetting properties of the substrate. We then solve the hydrodynamic problem for inviscid motions showing that the flow associated with the instability correlates with horizontal motion of the droplet's center-of-mass. We calculate the resulting ``walking speed.'' A novel feature is that the energy conversion mechanism is not unique, so long as the contact-line is mobilized. Hence, the walking droplet instability is potentially significant to a number of industrial applications, such as self-cleansing surfaces or energy harvesting devices.

  1. Relativistic Weierstrass random walks.

    PubMed

    Saa, Alberto; Venegeroles, Roberto

    2010-08-01

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

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

    PubMed

    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 (p<.001) and treadmill walking (p<.001). Thus, attuning steps to visual targets significantly affected CWS, 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. Motivating Distance Learners in Online Gaming Worlds

    ERIC Educational Resources Information Center

    Marvel, Michele D.

    2012-01-01

    Massively multiplayer online games (MMOGs) have potential as educational tools. Existing literature shows that MMOG-based courses can foster a more immediate sense of community among students than traditional distance learning interfaces. The immersive technology of MMOGs opens the door for students to be able to virtually walk through the college…

  4. Quantum random walk polynomial and quantum random walk measure

    NASA Astrophysics Data System (ADS)

    Kang, Yuanbao; Wang, Caishi

    2014-05-01

    In the paper, we introduce a quantum random walk polynomial (QRWP) that can be defined as a polynomial , which is orthogonal with respect to a quantum random walk measure (QRWM) on , such that the parameters are in the recurrence relations and satisfy . We firstly obtain some results of QRWP and QRWM, in which case the correspondence between measures and orthogonal polynomial sequences is one-to-one. It shows that any measure with respect to which a quantum random walk polynomial sequence is orthogonal is a quantum random walk measure. We next collect some properties of QRWM; moreover, we extend Karlin and McGregor's representation formula for the transition probabilities of a quantum random walk (QRW) in the interacting Fock space, which is a parallel result with the CGMV method. Using these findings, we finally obtain some applications for QRWM, which are of interest in the study of quantum random walk, highlighting the role played by QRWP and QRWM.

  5. Modulation of Head Movement Control During Walking

    NASA Technical Reports Server (NTRS)

    Mulavara, Ajitkumar P.; Verstraete, Mary C.; Bloomberg, Jacob J.; Paloski, William H. (Technical Monitor)

    1999-01-01

    The purpose of this study was to investigate the coordination of the head relative to the trunk within a gait cycle during gaze fixation. Nine normal subjects walked on a motorized treadmill driven at 1.79 m/sec (20 s trials) while fixing their gaze on a centrally located earth-fixed target positioned at a distance of 2m from their eyes. The relative motion of the head and the net torque acting on it relative to the trunk during the gait cycle were used as measures of coordination. It was found that the net torque applied to the head counteracts the destabilizing forces acting on the upper body during locomotion. The average net torque impulse was significantly different (p less than 0.05) between the heel strike and swing phases and were found to be symmetrical between the right and left leg events of the gait cycle. However, the average net displacement of the head relative to the trunk was maintained uniform (p greater than 0.05) throughout the gait cycle. Thus, the coordination of the motion of the head relative to the trunk during walking is dynamically modulated depending on the behavioral events occurring in the gait cycle. This modulation may serve to aid stabilization of the head by counteracting the force variations acting on the upper body that may aid in the visual fixing of targets during walking.

  6. Energetic consequences of human sociality: walking speed choices among friendly dyads.

    PubMed

    Wagnild, Janelle; Wall-Scheffler, Cara M

    2013-01-01

    Research has shown that individuals have an optimal walking speed-a speed which minimizes energy expenditure for a given distance. Because the optimal walking speed varies with mass and lower limb length, it also varies with sex, with males in any given population tending to have faster optimal walking speeds. This potentially creates an energetic dilemma for mixed-sex walking groups. Here we examine speed choices made by individuals of varying stature, mass, and sex walking together. Individuals (N = 22) walked around a track alone, with a significant other (with and without holding hands), and with friends of the same and opposite sex while their speeds were recorded every 100 m. Our findings show that males walk at a significantly slower pace to match the females' paces (p = 0.009), when the female is their romantic partner. The paces of friends of either same or mixed sex walking together did not significantly change (p>0.05). Thus significant pace adjustment appears to be limited to romantic partners. These findings have implications for both mobility and reproductive strategies of groups. Because the male carries the energetic burden by adjusting his pace (slowing down 7%), the female is spared the potentially increased caloric cost required to walk together. In energetically demanding environments, we will expect to find gender segregation in group composition, particularly when travelling longer distances.

  7. The influence of body configuration on motor imagery of walking in younger and older adults.

    PubMed

    Saimpont, A; Malouin, F; Tousignant, B; Jackson, P L

    2012-10-11

    Motor imagery (MI) refers to the mental simulation of a movement. It is used as a tool to improve motor function in several populations. In young adults, it has been repeatedly shown that MI of upper-limb movements is facilitated when one's posture is congruent with the movement to simulate. As MI training is notably used for improving locomotor-related activities in older populations, it may be questioned whether subjects' body configuration could also influence MI of walking movements and whether this influence is preserved with age. In the present study, we examined the impact of one's body position (congruent with walking: standing/incongruent with walking: sitting) on the duration of walking simulation over two distances (3m/6m), in 26 young (21 females, 5 males; mean: 23.2 ± 2.4 years) and 26 elderly (18 females, 8 males; mean: 72.7 ± 5.5 years) healthy subjects. It was found that, in both age groups, walking simulation times while standing were shorter than while sitting. Furthermore, walking simulation times in the standing position were closer to actual walking times to cover the same distances. The present findings extend to walking movements the notion that adopting a posture congruent with the movement to imagine facilitates the simulation process. They also suggest that, at least for simple walking tasks, this effect is maintained across the lifespan. The implication of our findings for optimizing MI training of locomotor-related activities is underlined.

  8. Numerical and Analytic Studies of Random-Walk Models.

    NASA Astrophysics Data System (ADS)

    Li, Bin

    We begin by recapitulating the universality approach to problems associated with critical systems, and discussing the role that random-walk models play in the study of phase transitions and critical phenomena. As our first numerical simulation project, we perform high-precision Monte Carlo calculations for the exponents of the intersection probability of pairs and triplets of ordinary random walks in 2 dimensions, in order to test the conformal-invariance theory predictions. Our numerical results strongly support the theory. Our second numerical project aims to test the hyperscaling relation dnu = 2 Delta_4-gamma for self-avoiding walks in 2 and 3 dimensions. We apply the pivot method to generate pairs of self-avoiding walks, and then for each pair, using the Karp-Luby algorithm, perform an inner -loop Monte Carlo calculation of the number of different translates of one walk that makes at least one intersection with the other. Applying a least-squares fit to estimate the exponents, we have obtained strong numerical evidence that the hyperscaling relation is true in 3 dimensions. Our great amount of data for walks of unprecedented length(up to 80000 steps), yield a updated value for the end-to-end distance and radius of gyration exponent nu = 0.588 +/- 0.001 (95% confidence limit), which comes out in good agreement with the renormalization -group prediction. In an analytic study of random-walk models, we introduce multi-colored random-walk models and generalize the Symanzik and B.F.S. random-walk representations to the multi-colored case. We prove that the zero-component lambdavarphi^2psi^2 theory can be represented by a two-color mutually -repelling random-walk model, and it becomes the mutually -avoiding walk model in the limit lambda to infty. However, our main concern and major break-through lies in the study of the two-point correlation function for the lambda varphi^2psi^2 theory with N > 0 components. By representing it as a two-color random-walk expansion

  9. Agile Walking Robot

    NASA Technical Reports Server (NTRS)

    Larimer, Stanley J.; Lisec, Thomas R.; Spiessbach, Andrew J.; Waldron, Kenneth J.

    1990-01-01

    Proposed agile walking robot operates over rocky, sandy, and sloping terrain. Offers stability and climbing ability superior to other conceptual mobile robots. Equipped with six articulated legs like those of insect, continually feels ground under leg before applying weight to it. If leg sensed unexpected object or failed to make contact with ground at expected point, seeks alternative position within radius of 20 cm. Failing that, robot halts, examines area around foot in detail with laser ranging imager, and replans entire cycle of steps for all legs before proceeding.

  10. How do you learn to walk? Thousands of steps and dozens of falls per day.

    PubMed

    Adolph, Karen E; Cole, Whitney G; Komati, Meghana; Garciaguirre, Jessie S; Badaly, Daryaneh; Lingeman, Jesse M; Chan, Gladys L Y; Sotsky, Rachel B

    2012-01-01

    A century of research on the development of walking has examined periodic gait over a straight, uniform path. The current study provides the first corpus of natural infant locomotion derived from spontaneous activity during free play. Locomotor experience was immense: Twelve- to 19-month-olds averaged 2,368 steps and 17 falls per hour. Novice walkers traveled farther faster than expert crawlers, but had comparable fall rates, which suggests that increased efficiency without increased cost motivates expert crawlers to transition to walking. After walking onset, natural locomotion improved dramatically: Infants took more steps, traveled farther distances, and fell less. Walking was distributed in short bouts with variable paths--frequently too short or irregular to qualify as periodic gait. Nonetheless, measures of periodic gait and of natural locomotion were correlated, which indicates that better walkers spontaneously walk more and fall less. Immense amounts of time-distributed, variable practice constitute the natural practice regimen for learning to walk. PMID:23085640

  11. Solar walk-off protection

    NASA Astrophysics Data System (ADS)

    Awaya, H.; Bedard, R.

    1985-04-01

    A point-focus solar concentrator is normally pointed toward the sun during operations to direct concentrated solar flux into the aperture of the receiver. If solar-tracking control is lost, severe damage may occur when the concentrated solar beam moves, or walks off the aperture across the face of the receiver. Alternative methods of solar walk-off prevention/protection for a specific assumed generic dish module and electric plant design are identified. The cost of a baseline case (no walk-off prevention/protection) is first calculated, including initial capital; recurring operating, maintenance, and capital replacement costs; and the cost of restoring the plant to operation following a solar walk-off. The alternative cases (with walk-off prevention/protection) are then evaluated by increasing the solar plant cost as a function of specific walk-off prevention/protection design alternatives and decreasing the cost of walk-off events given the specific level of prevention or protection offered by the alternative cases. The alternative plant designs are then compared with the baseline case and against each other by annualizing all costs. No single walk-off protection solution is universally applicable. Decisions concerning solar walk-off prevention/protection for specific installations must be based on engineering evaluations that consider the alternative choices given a specific plant, dish module, and site.

  12. Solar walk-off protection

    SciTech Connect

    Awaya, H.; Bedard, R.

    1985-04-01

    A point-focus solar concentrator is normally pointed toward the sun during operations to direct concentrated solar flux into the aperture of the receiver. If solar-tracking control is lost, severe damage may occur when the concentrated solar beam moves, or ''walks off'' the aperture across the face of the receiver. Alternative methods of solar walk-off prevention/protection for a specific assumed generic dish module and electric plant design are identified. The cost of a baseline case (no walk-off prevention/protection) is first calculated, including initial capital; recurring operating, maintenance, and capital replacement costs; and the cost of restoring the plant to operation following a solar walk-off. The alternative cases (with walk-off prevention/protection) are then evaluated by increasing the solar plant cost as a function of specific walk-off prevention/protection design alternatives and decreasing the cost of walk-off events given the specific level of prevention or protection offered by the alternative cases. The alternative plant designs are then compared with the baseline case and against each other by annualizing all costs. No single walk-off protection solution is universally applicable. Decisions concerning solar walk-off prevention/protection for specific installations must be based on engineering evaluations that consider the alternative choices given a specific plant, dish module, and site.

  13. Therapeutic efficacy of intensified walk training under the electrocardiogram telemetry in stroke induced lower limb dysfunction patients with heart failure

    PubMed Central

    Shen, Dantong; Huang, Huai; Yuan, Hui; Ye, Shuilin; Li, Min; Gu, Jing; Wang, Zhiwei

    2015-01-01

    Objectives: This study aimed to explore the therapeutic efficacy of intensified walk training under the electrocardiogram (ECG) telemetry in stroke induced lower limb dysfunction patients with heart failure. Material and Methods: A total of 40 patients with stroke induced lower limb dysfunction and heart failure were randomized into control group and walk training group (n=20 per group). Besides comprehensive rehabilitation, patients in walk training group received intensified walk training under the ECG telemetry and patients in control group received traditional training. After 5-week treatment, the FMA score of lower limbs, ADL score, 6-min walking distance and left ventricular ejection fraction (EF) by heart ultrasonography were determined. Results: There were no marked differences in the demographics between two groups at baseline, and no severe complications were observed during training in the walk training group. In control group, 6 patients developed lung edema which required further therapy. After 5-week training, the FMA score of lower limbs, ADL score and 6-min walk distance were improved to different extents, but the improvement was more obvious in walk training group (P<0.05). The left ventricular EF remained unchanged in both groups. Conclusions: In patients with stroke induced lower limb dysfunction and heart failure, routine rehabilitation in combination with additional walk training under the ECG telemetry is helpful to increase the training efficiency and training intensity and improve the low limb function and walk distance when the safety is assured. PMID:26629190

  14. The Reliability of Distance Run Tests for Children in Grades K-4.

    ERIC Educational Resources Information Center

    Rikli, Roberta E.; And Others

    1992-01-01

    Study determined test-retest reliability for 1-mile, three-quarter-mile, and half-mile distance run/walk tests for K-4 students. Students completed testing in various distance conditions. The distance run proved reliable with appropriate age/distance adjustments. Test scores were generally reliable in classifying students with regard to meeting…

  15. Indirect evidence for Levy walks in squeeze film damping

    SciTech Connect

    Schlamminger, S.; Hagedorn, C. A.; Gundlach, J. H.

    2010-06-15

    Molecular flow gas damping of mechanical motion in confined geometries, and its associated noise, is important in a variety of fields, including precision measurement, gravitational wave detection, and microelectromechanical systems devices. We used two torsion balance instruments to measure the strength and distance-dependence of 'squeeze film' damping. Measured quality factors derived from free decay of oscillation are consistent with gas particle superdiffusion in Levy walks and inconsistent with those expected from traditional Gaussian random walk particle motion. The distance-dependence of squeeze film damping observed in our experiments is in agreement with a parameter-free Monte Carlo simulation. The squeeze film damping of the motion of a plate suspended a distance d away from a parallel surface scales with a fractional power between d{sup -1} and d{sup -2}.

  16. Random-walk enzymes

    NASA Astrophysics Data System (ADS)

    Mak, Chi H.; Pham, Phuong; Afif, Samir A.; Goodman, Myron F.

    2015-09-01

    Enzymes that rely on random walk to search for substrate targets in a heterogeneously dispersed medium can leave behind complex spatial profiles of their catalyzed conversions. The catalytic signatures of these random-walk enzymes are the result of two coupled stochastic processes: scanning and catalysis. Here we develop analytical models to understand the conversion profiles produced by these enzymes, comparing an intrusive model, in which scanning and catalysis are tightly coupled, against a loosely coupled passive model. Diagrammatic theory and path-integral solutions of these models revealed clearly distinct predictions. Comparison to experimental data from catalyzed deaminations deposited on single-stranded DNA by the enzyme activation-induced deoxycytidine deaminase (AID) demonstrates that catalysis and diffusion are strongly intertwined, where the chemical conversions give rise to new stochastic trajectories that were absent if the substrate DNA was homogeneous. The C →U deamination profiles in both analytical predictions and experiments exhibit a strong contextual dependence, where the conversion rate of each target site is strongly contingent on the identities of other surrounding targets, with the intrusive model showing an excellent fit to the data. These methods can be applied to deduce sequence-dependent catalytic signatures of other DNA modification enzymes, with potential applications to cancer, gene regulation, and epigenetics.

  17. Random-walk enzymes.

    PubMed

    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.

  18. Random-walk enzymes

    PubMed Central

    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

  19. Random-walk enzymes.

    PubMed

    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. PMID:26465508

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

    NASA Astrophysics Data System (ADS)

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

    2010-02-01

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

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

    SciTech Connect

    Whitfield, James D.; Rodriguez-Rosario, Cesar A.; Aspuru-Guzik, Alan

    2010-02-15

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

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

    SciTech Connect

    Rodriguez-Rosario, Cesar A.; Aspuru-Guzik, Alan; Whitfield, James D.

    2010-02-23

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

  3. How do changes to the built environment influence walking behaviors? a longitudinal study within a university campus in Hong Kong

    PubMed Central

    2014-01-01

    Background Previous studies testing the association between the built environment and walking behavior have been largely cross-sectional and have yielded mixed results. This study reports on a natural experiment in which changes to the built environment were implemented at a university campus in Hong Kong. Longitudinal data on walking behaviors were collected using surveys, one before and one after changes to the built environment, to test the influence of changes to the built environment on walking behavior. Methods Built environment data are from a university campus in Hong Kong, and include land use, campus bus services, pedestrian network, and population density data collected from campus maps, the university developmental office, and field surveys. Walking behavior data were collected at baseline in March 2012 (n = 198) and after changes to the built environment from the same cohort of subjects in December 2012 (n = 169) using a walking diary. Geographic information systems (GIS) was used to map walking routes and built environment variables, and compare each subject’s walking behaviors and built environment exposure before and after the changes to the built environment. Walking behavior outcomes were changes in: i) walking distance, ii) destination-oriented walking, and iii) walked altitude range. Multivariable linear regression models were used to test for associations between changes to the built environment and changes in walking behaviors. Results Greater pedestrian network connectivity predicted longer walking distances and an increased likelihood of walking as a means of transportation. The increased use of recreational (vs. work) buildings, largely located at mid-range altitudes, as well as increased population density predicted greater walking distances.Having more bus services and a greater population density encouraged people to increase their walked altitude range. Conclusions In this longitudinal study, changes to the built environment

  4. Manipulating walking path configuration influences gait variability and six-minute walk test outcomes in older and younger adults.

    PubMed

    Barnett, C T; Bisele, M; Jackman, J S; Rayne, T; Moore, N C; Spalding, J L; Richardson, P; Plummer, B

    2016-02-01

    This study determined whether manipulations to walking path configuration influenced six-minute walk test (6MWT) outcomes and assessed how gait variability changes over the duration of the 6MWT in different walking path configurations. Healthy older (ODR) and younger (YNG) (n=24) adults completed familiarisation trials and five randomly ordered experimental trials of the 6MWT with walking configurations of; 5, 10 and 15m straight lines, a 6m by 3m rectangle (RECT), and a figure of eight (FIG8). Six-minute walk distance (6MWD) and walking speed (m.s(-1)) were recorded for all trials and the stride count recorded for experimental trials. Reflective markers were attached to the sacrum and feet with kinematic data recorded at 100 Hz by a nine-camera motion capture system for 5m, 15m and FIG8 trials, in order to calculate variability in stride and step length, stride width, stride and step time and double limb support time. Walking speeds and 6MWD were greatest in the 15m and FIG8 experimental trials in both groups (p<0.01). Step length and stride width variability were consistent over the 6MWT duration but greater in the 5m trial vs. the 15m and FIG8 trials (p<0.05). Stride and step time and double limb support time variability all reduced between 10 and 30 strides (p<0.01). Stride and step time variability were greater in the 5m vs. 15m and FIG8 trials (p<0.01). Increasing uninterrupted gait and walking path length results in improved 6MWT outcomes and decreased gait variability in older and younger adults.

  5. Biomechanics of walking with snowshoes.

    PubMed

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

    2012-03-01

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

  6. Walking tree heuristics for biological string alignment, gene location, and phylogenies

    NASA Astrophysics Data System (ADS)

    Cull, P.; Holloway, J. L.; Cavener, J. D.

    1999-03-01

    Basic biological information is stored in strings of nucleic acids (DNA, RNA) or amino acids (proteins). Teasing out the meaning of these strings is a central problem of modern biology. Matching and aligning strings brings out their shared characteristics. Although string matching is well-understood in the edit-distance model, biological strings with transpositions and inversions violate this model's assumptions. We propose a family of heuristics called walking trees to align biologically reasonable strings. Both edit-distance and walking tree methods can locate specific genes within a large string when the genes' sequences are given. When we attempt to match whole strings, the walking tree matches most genes, while the edit-distance method fails. We also give examples in which the walking tree matches substrings even if they have been moved or inverted. The edit-distance method was not designed to handle these problems. We include an example in which the walking tree "discovered" a gene. Calculating scores for whole genome matches gives a method for approximating evolutionary distance. We show two evolutionary trees for the picornaviruses which were computed by the walking tree heuristic. Both of these trees show great similarity to previously constructed trees. The point of this demonstration is that WHOLE genomes can be matched and distances calculated. The first tree was created on a Sequent parallel computer and demonstrates that the walking tree heuristic can be efficiently parallelized. The second tree was created using a network of work stations and demonstrates that there is suffient parallelism in the phylogenetic tree calculation that the sequential walking tree can be used effectively on a network.

  7. Nonreversal and nonrepeating quantum walks

    NASA Astrophysics Data System (ADS)

    Proctor, T. J.; Barr, K. E.; Hanson, B.; Martiel, S.; Pavlović, V.; Bullivant, A.; Kendon, V. M.

    2014-04-01

    We introduce a variation of the discrete-time quantum walk, the nonreversal quantum walk, which does not step back onto a position that it has just occupied. This allows us to simulate a dimer and we achieve it by introducing a different type of coin operator. The nonrepeating walk, which never moves in the same direction in consecutive time steps, arises by a permutation of this coin operator. We describe the basic properties of both walks and prove that the even-order joint moments of the nonrepeating walker are independent of the initial condition, being determined by five parameters derived from the coin instead. Numerical evidence suggests that the same is the case for the nonreversal walk. This contrasts strongly with previously studied coins, such as the Grover operator, where the initial condition can be used to control the standard deviation of the walker.

  8. Walking habits in elderly widows.

    PubMed

    Grimby, Agneta; Johansson, Asa K; Sundh, Valter; Grimby, Gunnar

    2008-01-01

    Walking habits were studied in 3 groups of elderly widows. The average walking time per week was calculated from interviews or questionnaires. There was in a small studied group a tendency for walking time to be lower at 3 and 12 months after loss than at 4 or 5 years. An increased odds ratio was demonstrated in larger groups of widows for walking less than 120 minutes per week in those who "did not feel healthy," or who had "musculoskeletal health problems," or "cardiovascular health problems." Widows from a population-based study also showed increased odds ratio for not walking as long with "lack of friends" and "not being active in associations." This was not found in married women from the population study. Our results indicate that newly bereaved women may reduce their physical activity, and that the change in exercise habits may be associated with reduced perception of being healthy and a decreased social network.

  9. Quantum walks on quotient graphs

    SciTech Connect

    Krovi, Hari; Brun, Todd A.

    2007-06-15

    A discrete-time quantum walk on a graph {gamma} is the repeated application of a unitary evolution operator to a Hilbert space corresponding to the graph. If this unitary evolution operator has an associated group of symmetries, then for certain initial states the walk will be confined to a subspace of the original Hilbert space. Symmetries of the original graph, given by its automorphism group, can be inherited by the evolution operator. We show that a quantum walk confined to the subspace corresponding to this symmetry group can be seen as a different quantum walk on a smaller quotient graph. We give an explicit construction of the quotient graph for any subgroup H of the automorphism group and illustrate it with examples. The automorphisms of the quotient graph which are inherited from the original graph are the original automorphism group modulo the subgroup H used to construct it. The quotient graph is constructed by removing the symmetries of the subgroup H from the original graph. We then analyze the behavior of hitting times on quotient graphs. Hitting time is the average time it takes a walk to reach a given final vertex from a given initial vertex. It has been shown in earlier work [Phys. Rev. A 74, 042334 (2006)] that the hitting time for certain initial states of a quantum walks can be infinite, in contrast to classical random walks. We give a condition which determines whether the quotient graph has infinite hitting times given that they exist in the original graph. We apply this condition for the examples discussed and determine which quotient graphs have infinite hitting times. All known examples of quantum walks with hitting times which are short compared to classical random walks correspond to systems with quotient graphs much smaller than the original graph; we conjecture that the existence of a small quotient graph with finite hitting times is necessary for a walk to exhibit a quantum speedup.

  10. Diffraction of walking droplets

    NASA Astrophysics Data System (ADS)

    Harris, Daniel M.; Pucci, Giuseppe; Bush, John W. M.

    2014-11-01

    We present results from our revisitation of the experiment of a walking droplet passing through a single slit, originally investigated by Couder & Fort (PRL, 2006). On each passage, the walker's trajectory is deviated as a result of the spatial confinement of its guiding wave. We explore the role of the droplet size and the bath's vibration amplitude on both the dynamics and statistics. We find the behavior to be remarkably sensitive to these control parameters. A complex physical picture emerges. The authors gratefully acknowledge the financial support of the NSF through Grant CMMI-1333242, DMH through the NSF Graduate Research Fellowship Program, and GP through the Programma Operativo Regionale (POR) Calabria - FSE 2007/2013.

  11. Water-walking devices

    NASA Astrophysics Data System (ADS)

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

    2007-11-01

    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 high-speed cinematography and flow visualization, we compare the functionality and dynamics of our devices with those of their natural counterparts.

  12. Water-walking devices

    NASA Astrophysics Data System (ADS)

    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.

  13. The TUM walking machines.

    PubMed

    Pfeiffer, Friedrich

    2007-01-15

    This paper presents some aspects of walking machine design with a special emphasis on the three machines MAX, MORITZ and JOHNNIE, having been developed at the Technical University of Munich within the last 20 years. The design of such machines is discussed as an iterative process improving the layout with every iteration. The control concepts are event-driven and follow logical rules, which have largely been transferred from neurobiological findings. At least for the six-legged machine MAX, a nearly perfect autonomy could be achieved, whereas for the biped JOHNNIE, a certain degree of autonomy could be realized by a vision system with appropriate decision algorithms. This vision system was developed by the group of Prof. G. Schmidt, TU-München. A more detailed description of the design and realization is presented for the biped JOHNNIE.

  14. Walking indoors, walking outdoors: an fMRI study.

    PubMed

    Dalla Volta, Riccardo; Fasano, Fabrizio; Cerasa, Antonio; Mangone, Graziella; Quattrone, Aldo; Buccino, Giovanni

    2015-01-01

    An observation/execution matching system for walking has not been assessed yet. The present fMRI study was aimed at assessing whether, as for object-directed actions, an observation/execution matching system is active for walking and whether the spatial context of walking (open or narrow space) recruits different neural correlates. Two experimental conditions were employed. In the execution condition, while being scanned, participants performed walking on a rolling cylinder located just outside the scanner. The same action was performed also while observing a video presenting either an open space (a country field) or a narrow space (a corridor). In the observation condition, participants observed a video presenting an individual walking on the same cylinder on which the actual action was executed, the open space video and the narrow space video, respectively. Results showed common bilateral activations in the dorsal premotor/supplementary motor areas and in the posterior parietal lobe for both execution and observation of walking, thus supporting a matching system for this action. Moreover, specific sectors of the occipital-temporal cortex and the middle temporal gyrus were consistently active when processing a narrow space versus an open one, thus suggesting their involvement in the visuo-motor transformation required when walking in a narrow space. We forward that the present findings may have implications for rehabilitation of gait and sport training. PMID:26483745

  15. Walking indoors, walking outdoors: an fMRI study

    PubMed Central

    Dalla Volta, Riccardo; Fasano, Fabrizio; Cerasa, Antonio; Mangone, Graziella; Quattrone, Aldo; Buccino, Giovanni

    2015-01-01

    An observation/execution matching system for walking has not been assessed yet. The present fMRI study was aimed at assessing whether, as for object-directed actions, an observation/execution matching system is active for walking and whether the spatial context of walking (open or narrow space) recruits different neural correlates. Two experimental conditions were employed. In the execution condition, while being scanned, participants performed walking on a rolling cylinder located just outside the scanner. The same action was performed also while observing a video presenting either an open space (a country field) or a narrow space (a corridor). In the observation condition, participants observed a video presenting an individual walking on the same cylinder on which the actual action was executed, the open space video and the narrow space video, respectively. Results showed common bilateral activations in the dorsal premotor/supplementary motor areas and in the posterior parietal lobe for both execution and observation of walking, thus supporting a matching system for this action. Moreover, specific sectors of the occipital–temporal cortex and the middle temporal gyrus were consistently active when processing a narrow space versus an open one, thus suggesting their involvement in the visuo-motor transformation required when walking in a narrow space. We forward that the present findings may have implications for rehabilitation of gait and sport training. PMID:26483745

  16. Preliminary exploration of the measurement of walking speed for the apoplectic people based on UHF RFID.

    PubMed

    Huang Hua-Lin; Mo Ling-Fei; Liu Ying-Jie; Li Cheng-Yang; Xu Qi-Meng; Wu Zhi-Tong

    2015-08-01

    The number of the apoplectic people is increasing while population aging is quickening its own pace. The precise measurement of walking speed is very important to the rehabilitation guidance of the apoplectic people. The precision of traditional measuring methods on speed such as stopwatch is relatively low, and high precision measurement instruments because of the high cost cannot be used widely. What's more, these methods have difficulty in measuring the walking speed of the apoplectic people accurately. UHF RFID tag has the advantages of small volume, low price, long reading distance etc, and as a wearable sensor, it is suitable to measure walking speed accurately for the apoplectic people. In order to measure the human walking speed, this paper uses four reader antennas with a certain distance to reads the signal strength of RFID tag. Because RFID tag has different RSSI (Received Signal Strength Indicator) in different distances away from the reader, researches on the changes of RSSI with time have been done by this paper to calculate walking speed. The verification results show that the precise measurement of walking speed can be realized by signal processing method with Gaussian Fitting-Kalman Filter. Depending on the variance of walking speed, doctors can predict the rehabilitation training result of the apoplectic people and give the appropriate rehabilitation guidance.

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

    NASA Astrophysics Data System (ADS)

    Aspuru-Guzik, Alan

    2010-03-01

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

  18. Functional distance in human gait transition.

    PubMed

    Abdolvahab, Mohammad; Carello, Claudia

    2015-10-01

    The emerging understanding of the behavioral transitions that accompany the ascending and descending method of limits is in terms of "functional distance" - the degree to which a perceiver is disengaged from ordinary exploratory activities. Increasing functional distance results in negative hysteresis in contrast to the classical positive hysteresis more typical of ongoing activity. In the present study of human gait transitions on a treadmill, the functional distance between a perceiver and ordinary exploratory activities was manipulated in two ways: (1) "Active" participants, walking or running on a treadmill, were asked to anticipate the gait that would be required if treadmill speed were increased or decreased; and (2) "passive" participants, standing off a moving treadmill, were asked to report the gait they would use if they were on the treadmill at its current speed. As expected, the increase of functional distance from (1) to (2) reduced the amount of classical hysteresis and promoted negative hysteresis, that is, a lower transition speed for walk-to-run transitions (ascending trials) than for run-to-walk transitions (descending trials). These results complement empirical findings in other behavioral transition experiments. More broadly, they signify the role of perception-action cycles for grounding natural on-going perception. In particular, they support the assertion that perception and action are intertwined and that lack of information about an impending action has consequences for perceptual judgments. PMID:26408863

  19. Social aggregation in pea aphids: experiment and random walk modeling.

    PubMed

    Nilsen, Christa; Paige, John; Warner, Olivia; Mayhew, Benjamin; Sutley, Ryan; Lam, Matthew; Bernoff, Andrew J; Topaz, Chad M

    2013-01-01

    From bird flocks to fish schools and ungulate herds to insect swarms, social biological aggregations are found across the natural world. An ongoing challenge in the mathematical modeling of aggregations is to strengthen the connection between models and biological data by quantifying the rules that individuals follow. We model aggregation of the pea aphid, Acyrthosiphon pisum. Specifically, we conduct experiments to track the motion of aphids walking in a featureless circular arena in order to deduce individual-level rules. We observe that each aphid transitions stochastically between a moving and a stationary state. Moving aphids follow a correlated random walk. The probabilities of motion state transitions, as well as the random walk parameters, depend strongly on distance to an aphid's nearest neighbor. For large nearest neighbor distances, when an aphid is essentially isolated, its motion is ballistic with aphids moving faster, turning less, and being less likely to stop. In contrast, for short nearest neighbor distances, aphids move more slowly, turn more, and are more likely to become stationary; this behavior constitutes an aggregation mechanism. From the experimental data, we estimate the state transition probabilities and correlated random walk parameters as a function of nearest neighbor distance. With the individual-level model established, we assess whether it reproduces the macroscopic patterns of movement at the group level. To do so, we consider three distributions, namely distance to nearest neighbor, angle to nearest neighbor, and percentage of population moving at any given time. For each of these three distributions, we compare our experimental data to the output of numerical simulations of our nearest neighbor model, and of a control model in which aphids do not interact socially. Our stochastic, social nearest neighbor model reproduces salient features of the experimental data that are not captured by the control.

  20. Social aggregation in pea aphids: experiment and random walk modeling.

    PubMed

    Nilsen, Christa; Paige, John; Warner, Olivia; Mayhew, Benjamin; Sutley, Ryan; Lam, Matthew; Bernoff, Andrew J; Topaz, Chad M

    2013-01-01

    From bird flocks to fish schools and ungulate herds to insect swarms, social biological aggregations are found across the natural world. An ongoing challenge in the mathematical modeling of aggregations is to strengthen the connection between models and biological data by quantifying the rules that individuals follow. We model aggregation of the pea aphid, Acyrthosiphon pisum. Specifically, we conduct experiments to track the motion of aphids walking in a featureless circular arena in order to deduce individual-level rules. We observe that each aphid transitions stochastically between a moving and a stationary state. Moving aphids follow a correlated random walk. The probabilities of motion state transitions, as well as the random walk parameters, depend strongly on distance to an aphid's nearest neighbor. For large nearest neighbor distances, when an aphid is essentially isolated, its motion is ballistic with aphids moving faster, turning less, and being less likely to stop. In contrast, for short nearest neighbor distances, aphids move more slowly, turn more, and are more likely to become stationary; this behavior constitutes an aggregation mechanism. From the experimental data, we estimate the state transition probabilities and correlated random walk parameters as a function of nearest neighbor distance. With the individual-level model established, we assess whether it reproduces the macroscopic patterns of movement at the group level. To do so, we consider three distributions, namely distance to nearest neighbor, angle to nearest neighbor, and percentage of population moving at any given time. For each of these three distributions, we compare our experimental data to the output of numerical simulations of our nearest neighbor model, and of a control model in which aphids do not interact socially. Our stochastic, social nearest neighbor model reproduces salient features of the experimental data that are not captured by the control. PMID:24376691

  1. Social Aggregation in Pea Aphids: Experiment and Random Walk Modeling

    PubMed Central

    Nilsen, Christa; Paige, John; Warner, Olivia; Mayhew, Benjamin; Sutley, Ryan; Lam, Matthew; Bernoff, Andrew J.; Topaz, Chad M.

    2013-01-01

    From bird flocks to fish schools and ungulate herds to insect swarms, social biological aggregations are found across the natural world. An ongoing challenge in the mathematical modeling of aggregations is to strengthen the connection between models and biological data by quantifying the rules that individuals follow. We model aggregation of the pea aphid, Acyrthosiphon pisum. Specifically, we conduct experiments to track the motion of aphids walking in a featureless circular arena in order to deduce individual-level rules. We observe that each aphid transitions stochastically between a moving and a stationary state. Moving aphids follow a correlated random walk. The probabilities of motion state transitions, as well as the random walk parameters, depend strongly on distance to an aphid's nearest neighbor. For large nearest neighbor distances, when an aphid is essentially isolated, its motion is ballistic with aphids moving faster, turning less, and being less likely to stop. In contrast, for short nearest neighbor distances, aphids move more slowly, turn more, and are more likely to become stationary; this behavior constitutes an aggregation mechanism. From the experimental data, we estimate the state transition probabilities and correlated random walk parameters as a function of nearest neighbor distance. With the individual-level model established, we assess whether it reproduces the macroscopic patterns of movement at the group level. To do so, we consider three distributions, namely distance to nearest neighbor, angle to nearest neighbor, and percentage of population moving at any given time. For each of these three distributions, we compare our experimental data to the output of numerical simulations of our nearest neighbor model, and of a control model in which aphids do not interact socially. Our stochastic, social nearest neighbor model reproduces salient features of the experimental data that are not captured by the control. PMID:24376691

  2. The Six-Minute Walk Test for Adults with Intellectual Disability: A Study of Validity and Reliability

    ERIC Educational Resources Information Center

    Nasuti, Gabriella; Stuart-Hill, Lynneth; Temple, Viviene A.

    2013-01-01

    Background: The Six-Minute Walk Test (6MWT) has been used with clinical and healthy populations to assess functional capacity and cardiovascular fitness. The aim of this study was to determine the test-retest reliability of a modified-6MWT as well as concurrent validity of walk distance with peak oxygen uptake (VO[subscript 2] peak). Method:…

  3. Center of mass mechanics of chimpanzee bipedal walking.

    PubMed

    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. PMID:25407636

  4. Big power from walking

    NASA Astrophysics Data System (ADS)

    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.

  5. Integrated photonic quantum walks

    NASA Astrophysics Data System (ADS)

    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.

  6. Quantum snake walk on graphs

    SciTech Connect

    Rosmanis, Ansis

    2011-02-15

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

  7. [Human walk in spacesuit as a self-oscillating process].

    PubMed

    Panfilov, V E; Gurfinkel', V S

    2009-01-01

    A series of 40 biomechanic and physiological tests of semi-rigid and flexible spacesuits as possible candidates for Moon explorations purposes were conducted with involvement of 20 volunteered subjects. Ability to walk in the spacesuits with the internal positive pressure of 0.4 kg/cm2 in the normal gravity was assessed simultaneously with energy expenditure for moving over preset distances. Also, mating of the leg movements with the spacesuit shell was investigated The longest distance test elicited the fact of acquisition of stable motor skills in the unusual circumstances. The acquired motor skills bring about restructuring of step kinematics and make equal knee flexures during leg transfer and stepping on platform (matching the angular movement of the spacesuit knee joint) to an accuracy of tenths of degree. This phenomenon is used by the authors as the ground for proposing a reasoned optimization of the walk pattern in spacesuits as a self-oscillating process.

  8. [Human walk in spacesuit as a self-oscillating process].

    PubMed

    Panfilov, V E; Gurfinkel', V S

    2009-01-01

    A series of 40 biomechanic and physiological tests of semi-rigid and flexible spacesuits as possible candidates for Moon explorations purposes were conducted with involvement of 20 volunteered subjects. Ability to walk in the spacesuits with the internal positive pressure of 0.4 kg/cm2 in the normal gravity was assessed simultaneously with energy expenditure for moving over preset distances. Also, mating of the leg movements with the spacesuit shell was investigated The longest distance test elicited the fact of acquisition of stable motor skills in the unusual circumstances. The acquired motor skills bring about restructuring of step kinematics and make equal knee flexures during leg transfer and stepping on platform (matching the angular movement of the spacesuit knee joint) to an accuracy of tenths of degree. This phenomenon is used by the authors as the ground for proposing a reasoned optimization of the walk pattern in spacesuits as a self-oscillating process. PMID:20169739

  9. Random walk through fractal environments.

    PubMed

    Isliker, H; Vlahos, L

    2003-02-01

    We analyze random walk through fractal environments, embedded in three-dimensional, permeable space. Particles travel freely and are scattered off into random directions when they hit the fractal. The statistical distribution of the flight increments (i.e., of the displacements between two consecutive hittings) is analytically derived from a common, practical definition of fractal dimension, and it turns out to approximate quite well a power-law in the case where the dimension D(F) of the fractal is less than 2, there is though, always a finite rate of unaffected escape. Random walks through fractal sets with D(F)< or =2 can thus be considered as defective Levy walks. The distribution of jump increments for D(F)>2 is decaying exponentially. The diffusive behavior of the random walk is analyzed in the frame of continuous time random walk, which we generalize to include the case of defective distributions of walk increments. It is shown that the particles undergo anomalous, enhanced diffusion for D(F)<2, the diffusion is dominated by the finite escape rate. Diffusion for D(F)>2 is normal for large times, enhanced though for small and intermediate times. In particular, it follows that fractals generated by a particular class of self-organized criticality models give rise to enhanced diffusion. The analytical results are illustrated by Monte Carlo simulations.

  10. Improving the accuracy of walking piezo motors.

    PubMed

    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.

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

    NASA Astrophysics Data System (ADS)

    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

  12. Assessment of a Solar System Walk

    NASA Astrophysics Data System (ADS)

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

    2010-04-01

    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 Washington, D.C., starting at the Smithsonian Air and Space museum.1 A pioneering model and inspiration for our own is on the campus of the University of Colorado in Boulder,2 and there are others.3 Those at science museums are often used by the general public and field-trip groups, while the ones on college campuses are also used by students of introductory astronomy.

  13. Discrete mechanics and special relativistic random walks.

    PubMed

    Wall, F T

    1988-05-01

    Random walks with step lengths equal to the shortest possible physically meaningful distances are considered from the point of view of special relativity involving two observers moving uniformly with respect to each other. A requirement of statistical equivalence of the probability distributions seen by those observers leads to the Lorentz transformations, provided a randomly moving particle shifts from one submicroscopic cell of uncertainty to a neighbor with a speed equivalent to that of light. Ordinary smooth motion would appear to involve a tremendous amount of submicroscopic back and forth randomness subject to a statistical bias favoring a particular direction. The diffusive nature of the motion naturally leads to a spreading of the probability distribution.

  14. Complex networks in the Euclidean space of communicability distances.

    PubMed

    Estrada, Ernesto

    2012-06-01

    We study the properties of complex networks embedded in a Euclidean space of communicability distances. The communicability distance between two nodes is defined as the difference between the weighted sum of walks self-returning to the nodes and the weighted sum of walks going from one node to the other. We give some indications that the communicability distance identifies the least crowded routes in networks where simultaneous submission of packages is taking place. We define an index Q based on communicability and shortest path distances, which allows reinterpreting the "small-world" phenomenon as the region of minimum Q in the Watts-Strogatz model. It also allows the classification and analysis of networks with different efficiency of spatial uses. Consequently, the communicability distance displays unique features for the analysis of complex networks in different scenarios.

  15. Effect of Viewing Plane on Perceived Distances in Real and Virtual Environments

    ERIC Educational Resources Information Center

    Geuss, Michael N.; Stefanucci, Jeanine K.; Creem-Regehr, Sarah H.; Thompson, William B.

    2012-01-01

    Three experiments examined perceived absolute distance in a head-mounted display virtual environment (HMD-VE) and a matched real-world environment, as a function of the type and orientation of the distance viewed. In Experiment 1, participants turned and walked, without vision, a distance to match the viewed interval for both egocentric…

  16. 10 CFR 431.302 - Definitions concerning walk-in coolers and walk-in freezers.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... cooler or walk-in freezer that are not part of its refrigeration system. K-factor means the thermal conductivity of a material. Manufacturer of a walk-in cooler or walk-in freezer means any person who:...

  17. 10 CFR 431.302 - Definitions concerning walk-in coolers and walk-in freezers.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... cooler or walk-in freezer that are not part of its refrigeration system. K-factor means the thermal conductivity of a material. Manufacturer of a walk-in cooler or walk-in freezer means any person who:...

  18. 10 CFR 431.302 - Definitions concerning walk-in coolers and walk-in freezers.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... cooler or walk-in freezer that are not part of its refrigeration system. K-factor means the thermal conductivity of a material. Manufacturer of a walk-in cooler or walk-in freezer means any person who:...

  19. The relationship between walking speed and changes in cardiovascular risk factors during a 12-day walking tour to Santiago de Compostela: a cohort study

    PubMed Central

    Bemelmans, Remy H H; Blommaert, Paulus P; Wassink, Annemarie M J; Coll, Blai; Spiering, Wilko; van der Graaf, Yolanda

    2012-01-01

    Objectives Physical exercise has beneficial effects on cardiovascular risk factors. Knowledge about the effect of exercise intensity, specifically walking speed, on cardiovascular risk factors is limited. We report the relationship between walking speed and changes in cardiovascular risk factors in participants of a 12-day walking tour to Santiago de Compostela. Design Prospective cohort study. Setting Single-centre study with healthy middle-aged volunteers. Participants Healthy middle-aged men (n=15) and women (n=14). Subjects using lipid-lowering medication were excluded. Intervention Participants walked 281±10 km of the classical route to Santiago de Compostela in 12 days in 2009. Primary and secondary outcome measures Walking speed was recorded and blood pressure, weight, waist circumference, lipids and glucose were measured every other day. Changes in risk factors were compared between gender-pooled groups with faster and slower walking speed. Second, the relationship between walking speed and changes in risk factors was quantified using a linear mixed effects model. Results In the faster walking speed (4.6±0.2 km/h) group, high-density lipoprotein cholesterol (HDL-c) increased more than in the slower walking speed (4.1±0.2 km/h) group (difference in change between groups: 0.20; 95% CI −0.02 to 0.42 mmol/l), while low-density lipoprotein cholesterol (LDL-c) and total cholesterol decreased more in the slower walking speed group (differences in changes between groups: LDL-c: −0.50; 95% CI −0.88 to −0.12 mmol/l and total cholesterol: −0.75; 95% CI −1.19 to −0.31 mmol/l). A 1 km/h higher walking speed was related to an increase in HDL-c (0.24; 95% CI 0.12 to 0.30 mmol/l), LDL-c (0.18; 95% CI −0.16 to 0.42 mmol/l) and total cholesterol (0.36; 95% CI 0.12 to 0.60 mmol/l), adjusted for age, gender, smoking, body mass index and heart rate, during the whole walking tour. Conclusions Walking the same distance faster improves HDL

  20. Estimation of detection thresholds for redirected walking techniques.

    PubMed

    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.

  1. Unitary equivalent classes of one-dimensional quantum walks

    NASA Astrophysics Data System (ADS)

    Ohno, Hiromichi

    2016-09-01

    This study investigates unitary equivalent classes of one-dimensional quantum walks. We prove that one-dimensional quantum walks are unitary equivalent to quantum walks of Ambainis type and that translation-invariant one-dimensional quantum walks are Szegedy walks. We also present a necessary and sufficient condition for a one-dimensional quantum walk to be a Szegedy walk.

  2. Walking Devices Used by the Elderly Living in Rural Areas of Thailand

    PubMed Central

    Patcharawan, SUWANNARAT; THAWEEWANNAKIJ, Thiwabhorn; KAEWSANMUNG, Supapon; KAEWJOHO, Chonticha; SAENGSUWAN, Jiamjit; AMATACHAYA, Sugalya

    2015-01-01

    Background: The use of all types of external devices was previously investigated for elderly with and without orthopaedic problems of a developed country. This study describes the proportion, types and the reasons of using a walking device in elderly who live in many rural areas of Thailand. Methods: Participants (n = 390) were interviewed using a questionnaire to ascertain their demographics, health status and types of walking device required for daily activities. Results: Forty-one participants (11%) used a walking device, particularly when walking long distances due to a fear of falling, musculoskeletal pain, and impaired walking ability. The proportion of walking devices used dramatically increased in participants aged 75 years and over (six times of those aged 60–74 years). Most of the participants used a modified walking stick by their own determination (81%), while only 7% used one according to medical prescription. A significant increase in the need of a walking device was seen in participants aged 75 years and over (OR = 13.9; 95% CI 5.9–32.7; P < 0.001), with a medical problem (OR = 45.9; 95% CI 6.7–73.4; P < 0.001) and who required regular medication (OR = 12.7; 95% CI 5.0–33.6; P = 0.001). Conclusion: The findings emphasise the importance of a community health service to promote health status, particularly before 75 years of age. PMID:26023295

  3. Learning to tune the antero-posterior propulsive forces during walking: a necessary skill for mastering upright locomotion in toddlers.

    PubMed

    Bril, Blandine; Dupuy, Lucile; Dietrich, Gilles; Corbetta, Daniela

    2015-10-01

    This study examines the process of learning to walk from a functional perspective. To move forward, one must generate and control propulsive forces. To achieve this, it is necessary to create and tune a distance between the centre of mass (CoM) and the centre of pressure (CoP) along the antero-posterior axis. We hypothesize that learning to walk consists of learning how to calibrate these self-generated propulsive forces to control such distance. We investigated this question with six infants (three girls and three boys) who we followed up weekly for the first 8 weeks after the onset of walking and then biweekly until they reached 14-16 weeks of walking experience. The infants' walking patterns (kinematics and propelling forces) were captured via synched motion analysis and force plate. The results show that the distance between the CoM and the CoP along the antero-posterior axis increased rapidly during the first months of learning to walk and that this increase was correlated with an increase in velocity. The initial small values of (CoM-CoP) observed at walking onset, coupled with small velocity are interpreted as the solution infants adopted to satisfy a compromise between the need to generate propulsive forces to move forward while simultaneously controlling the disequilibrium resulting from creating a with distance between the CoM and CoP.

  4. Walking on ballast impacts balance.

    PubMed

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

    2014-01-01

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

  5. Knots in finite memory walks

    NASA Astrophysics Data System (ADS)

    Horwath, Eric; Clisby, Nathan; Virnau, Peter

    2016-09-01

    We investigate the occurrence and size of knots in a continuum polymer model with finite memory via Monte Carlo simulations. Excluded volume interactions are local and extend only to a fixed number of successive beads along the chain, ensuring that at short length scales the excluded volume effect dominates, while at longer length scales the polymer behaves like a random walk. As such, this model may be useful for understanding the behavior of polymers in a melt or semi-dilute solution, where exactly the same crossover is believed to occur. In particular, finite memory walks allow us to investigate the role of local interactions in the transition from highly knotted ideal polymers to almost unknotted self-avoiding polymers. Even though knotting decreases substantially when a few next-nearest neighbor interactions are considered, we find that the knotting probability of a polymer chain of modest length of 500 steps only decays slowly as a function of the range of the excluded volume interaction. In this context, we also find evidence that for length scales up to the interaction length the knotting behavior of the finite memory walk resembles that of a self-avoiding walk (effectively suppressing small knots), while for larger length scales it resembles that of a random walk.

  6. Six-minute walk test in children and adolescents with renal diseases: tolerance, reproducibility and comparison with healthy subjects

    PubMed Central

    Watanabe, Flávia Tieme; Koch, Vera Herminia Kalika; Juliani, Regina Celia Turola Passos; Cunha, Maristela Trevisan

    2016-01-01

    OBJECTIVES: To evaluate exercise tolerance and the reproducibility of the six-minute walk test in Brazilian children and adolescents with chronic kidney disease and to compare their functional exercise capacities with reference values for healthy children. METHODS: This cross-sectional study assessed the use of the six-minute walk test in children and adolescents aged 6-16 with stage V chronic kidney disease. For statistical analysis of exercise tolerance, including examinations of correlations and comparisons with reference values, the longest walked distances were considered. The reproducibility of the six-minute walk test was assessed using intraclass correlation coefficients. RESULTS: A total of 38 patients (14 females and 24 males) were evaluated, including 5 on peritoneal dialysis, 12 on hemodialysis and 21 who had undergone renal transplantation, with a median age of 11.2 years (6.5-16). The median walked distance was 538.5 meters (413-685) and the six-minute walk test was found to be reproducible. The walked distance was significantly correlated with age (r=0.66), weight (r=0.76), height (r=0.82), the height Z score (r=0.41), hemoglobin (r=0.46), hematocrit (r=0.47) and post-test systolic blood pressure (r=0.39). The chronic kidney disease patients predicted walked distance was 84.1% of the reference value according to age, 90.6% according to age-corrected height and 87.4% according to a predictive equation. CONCLUSIONS: The stage V chronic kidney disease patients had a significantly decreased functional exercise capacity, as measured by the six-minute walk test, compared with the healthy pediatric reference values. In addition, the six-minute walk test was shown to be well tolerated, reliable and applicable as a low-cost tool to monitor functional exercise capacity in patients with renal disease. PMID:26872080

  7. Szegedy's quantum walk with queries

    NASA Astrophysics Data System (ADS)

    Santos, Raqueline A. M.

    2016-08-01

    When searching for a marked vertex in a graph, Szegedy's usual search operator is defined by using the transition probability matrix of the random walk with absorbing barriers at the marked vertices. Instead of using this operator, we analyze searching with Szegedy's quantum walk by using reflections around the marked vertices, that is, the standard form of quantum query. We show we can boost the probability to 1 of finding a marked vertex in the complete graph. Numerical simulations suggest that the success probability can be improved for other graphs, like the two-dimensional grid. We also prove that, for a certain class of graphs, we can express Szegedy's search operator, obtained from the absorbing walk, using the standard query model.

  8. After Talking the Talk, Now Walk the Walk

    ERIC Educational Resources Information Center

    Vukovic, Paul

    2011-01-01

    In this article, the author describes what his students are doing following the ATM Easter conference in Telford, where he was inspired by a workshop entitled "Vitamin D Maths," conducted by Jocelyn D'Arcy. He describes an activity that allows his Year 11 students to walk through angles drawn on the floors. This topic will now literally be given a…

  9. Greedy adaptive walks on a correlated fitness landscape.

    PubMed

    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.

  10. Kinematic and stability motion limits for a hexapod walking machine

    NASA Astrophysics Data System (ADS)

    Dunton, Elizabeth M.

    1995-03-01

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

  11. Defining Distance Learning and Distance Education.

    ERIC Educational Resources Information Center

    King, Frederick B.; Young, Michael F.; Drivere-Richmond, Kelly; Schrader, P. G.

    2001-01-01

    This paper offers precise definitions of distance learning and distance education, and their interrelationship. First, a single definition of learning is proposed, and then the concept of learning is broken down into three subcategories: instruction, exploration, and serendipity. Each is defined and the concepts of distance learning and distance…

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

    NASA Astrophysics Data System (ADS)

    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.

  13. Dissipative quantum computing with open quantum walks

    SciTech Connect

    Sinayskiy, Ilya; Petruccione, Francesco

    2014-12-04

    An open quantum walk approach to the implementation of a dissipative quantum computing scheme is presented. The formalism is demonstrated for the example of an open quantum walk implementation of a 3 qubit quantum circuit consisting of 10 gates.

  14. On Convergent Probability of a Random Walk

    ERIC Educational Resources Information Center

    Lee, Y.-F.; Ching, W.-K.

    2006-01-01

    This note introduces an interesting random walk on a straight path with cards of random numbers. The method of recurrent relations is used to obtain the convergent probability of the random walk with different initial positions.

  15. Walk around the Block Curriculum.

    ERIC Educational Resources Information Center

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

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

  16. Closed walks for community detection

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

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

  17. Successful Statewide Walking Program Websites

    ERIC Educational Resources Information Center

    Teran, Bianca Maria; Hongu, Nobuko

    2012-01-01

    Statewide Extension walking programs are making an effort to increase physical activity levels in America. An investigation of all 20 of these programs revealed that 14 use websites as marketing and educational tools, which could prove useful as the popularity of Internet communities continues to grow. Website usability information and an analysis…

  18. A Walk to the Well.

    ERIC Educational Resources Information Center

    Weir, Phil

    1994-01-01

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

  19. Behavior Management by Walking Around

    ERIC Educational Resources Information Center

    Boardman, Randolph M.

    2004-01-01

    An emerging concept from the field of business is to manage organizations by wandering around and engaging staff and consumers in informal interactions. The author extends these ideas to settings serving children and youth. In the best seller, In Search of Excellence, Peters and Waterman (1982) introduced Management by Walking Around (MBWA) as an…

  20. "A Walk with Robert Frost."

    ERIC Educational Resources Information Center

    Gustafson, John A.

    1984-01-01

    Describes a field exercise using nature poetry to enlarge and give emotional content to ecological ideas. The trip involves walking in silence (except during poetry readings) through a natural area where objects or situations illustrated in the poetry are found. Recommended readings on specific details and ideas are provided. (BC)

  1. A Leadership Walk across Gettysburg

    ERIC Educational Resources Information Center

    Millward, Robert E.

    2009-01-01

    School administrators find the Civil War battlefield an appropriate venue for fully appreciating the role of vision, mentoring and the power of words. The author, a professor at Indiana University of Pennsylvania, has organized leadership walks across Gettysburg for superintendents and principals for a decade. This article describes the…

  2. Listening Walks and Singing Maps

    ERIC Educational Resources Information Center

    Cardany, Audrey Berger

    2011-01-01

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

  3. Path integration: effect of curved path complexity and sensory system on blindfolded walking.

    PubMed

    Koutakis, Panagiotis; Mukherjee, Mukul; Vallabhajosula, Srikant; Blanke, Daniel J; Stergiou, Nicholas

    2013-02-01

    Path integration refers to the ability to integrate continuous information of the direction and distance traveled by the system relative to the origin. Previous studies have investigated path integration through blindfolded walking along simple paths such as straight line and triangles. However, limited knowledge exists regarding the role of path complexity in path integration. Moreover, little is known about how information from different sensory input systems (like vision and proprioception) contributes to accurate path integration. The purpose of the current study was to investigate how sensory information and curved path complexity affect path integration. Forty blindfolded participants had to accurately reproduce a curved path and return to the origin. They were divided into four groups that differed in the curved path, circle (simple) or figure-eight (complex), and received either visual (previously seen) or proprioceptive (previously guided) information about the path before they reproduced it. The dependent variables used were average trajectory error, walking speed, and distance traveled. The results indicated that (a) both groups that walked on a circular path and both groups that received visual information produced greater accuracy in reproducing the path. Moreover, the performance of the group that received proprioceptive information and later walked on a figure-eight path was less accurate than their corresponding circular group. The groups that had the visual information also walked faster compared to the group that had proprioceptive information. Results of the current study highlight the roles of different sensory inputs while performing blindfolded walking for path integration.

  4. Path Integration: Effect of Curved Path Complexity and Sensory System on Blindfolded Walking

    PubMed Central

    Koutakis, Panagiotis; Mukherjee, Mukul; Vallabhajosula, Srikant; Blanke, Daniel J.; Stergiou, Nicholas

    2012-01-01

    Path integration refers to the ability to integrate continuous information of the direction and distance travelled by the system relative to the origin. Previous studies have investigated path integration through blindfolded walking along simple paths such as straight line and triangles. However, limited knowledge exists regarding the role of path complexity in path integration. Moreover, little is known about how information from different sensory input systems (like vision and proprioception) contributes to accurate path integration. The purpose of the current study was to investigate how sensory information and curved path complexity affect path integration. Forty blindfolded participants had to accurately reproduce a curved path and return to the origin. They were divided into four groups that differed in the curved path, circle (simple) or figure-eight (complex), and received either visual (previously seen) or proprioceptive (previously guided) information about the path before they reproduced it. The dependent variables used were average trajectory error, walking speed, and distance travelled. The results indicated that (a) both groups that walked on a circular path and both groups that received visual information produced greater accuracy in reproducing the path. Moreover, the performance of the group that received proprioceptive information and later walked on a figure-eight path was less accurate than their corresponding circular group. The groups that had the visual information also walked faster compared to the group that had proprioceptive information. Results of the current study highlight the roles of different sensory inputs while performing blindfolded walking for path integration. PMID:22840893

  5. Compliance potential mapping: a tool to assess potential contributions of walking towards physical activity guidelines

    PubMed Central

    2014-01-01

    Background Walking for transport is increasingly considered an important component for meeting physical activity guidelines. This is true for individuals of all ages, and particularly important for seniors, for whom other physical activities may not be recommended. In order to evaluate the potential contributions of walking to physical activity, in this paper the concept of Compliance Potential Mapping is introduced. The concept is illustrated using seniors as a case study. Methods Based on estimates of walking trip distance and frequency, estimates of expected total daily walking distance are obtained. These estimates are converted to weekly walking minutes, which are in turn compared to recommended physical activity guidelines for seniors. Once estimates of travel behavior are available, the approach is straightforward and based on relatively simple map algebra operations. Results Compliance Potential Mapping as a tool to assess the potential contributions of walking towards physical activity is demonstrated using data from Montreal’s 2008 travel survey. The results indicate that the central parts of Montreal Island display higher potential for compliance with physical activity guidelines, but with variations according to age, income, occupation, possession of driver’s license and vehicle, and neighborhood and accessibility parameters. Conclusions Compliance Potential Maps offer valuable information for public health and transportation planning and policy analysis. PMID:24885360

  6. Developmental Continuity? Crawling, Cruising, and Walking

    ERIC Educational Resources Information Center

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

    2011-01-01

    This research examined developmental continuity between "cruising" (moving sideways holding onto furniture for support) and walking. Because cruising and walking involve locomotion in an upright posture, researchers have assumed that cruising is functionally related to walking. Study 1 showed that most infants crawl and cruise concurrently prior…

  7. Development of independent walking in toddlers.

    PubMed

    Ivanenko, Yuri P; Dominici, Nadia; Lacquaniti, Francesco

    2007-04-01

    Surprisingly, despite millions of years of bipedal walking evolution, the gravity-related pendulum mechanism of walking does not seem to be implemented at the onset of independent walking, requiring each toddler to develop it. We discuss the precursor of the mature locomotor pattern in infants as an optimal starting point strategy for gait maturation. PMID:17417053

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  10. A bioinspired multi-modal flying and walking robot.

    PubMed

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

    2015-01-19

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

  11. A bioinspired multi-modal flying and walking robot.

    PubMed

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

    2015-01-01

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

  12. Random walk theory applied to electron avalanche formation

    NASA Technical Reports Server (NTRS)

    Englert, G. W.

    1974-01-01

    Use of microscopic detail in random walk theory describing the initial formations of a large number of avalanches shows that concomitant electron transport coefficients quickly relax to equilibrium values. This enables the use of random walks having step sizes and probabilities based only on local electric field strengths and densities. A self-consistent avalanche solution which accounts for collective long range Coulomb interactions as well as short range elastic and inelastic collisions between electrons and background atoms is demonstrated for helium. Avalanche growth retardation followed by an abrupt growth augmentation as time proceeds is shown to be associated with the formation of regions of charge density extrema near the avalanche axis and within the axial distance covered by the electron swarm.

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

    ERIC Educational Resources Information Center

    Alfonzo, Mariela

    2005-01-01

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

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed

    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.

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

    PubMed

    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. PMID:26963741

  17. Directed random walk with random restarts: The Sisyphus random walk

    NASA Astrophysics Data System (ADS)

    Montero, Miquel; Villarroel, Javier

    2016-09-01

    In this paper we consider a particular version of the random walk with restarts: random reset events which suddenly bring the system to the starting value. We analyze its relevant statistical properties, like the transition probability, and show how an equilibrium state appears. Formulas for the first-passage time, high-water marks, and other extreme statistics are also derived; we consider counting problems naturally associated with the system. Finally we indicate feasible generalizations useful for interpreting different physical effects.

  18. Gaze characteristics of freely walking blowflies Calliphora vicina in a goal-directed task.

    PubMed

    Kress, Daniel; Egelhaaf, Martin

    2014-09-15

    In contrast to flying flies, walking flies experience relatively strong rotational gaze shifts, even during overall straight phases of locomotion. These gaze shifts are caused by the walking apparatus and modulated by the stride frequency. Accordingly, even during straight walking phases, the retinal image flow is composed of both translational and rotational optic flow, which might affect spatial vision, as well as fixation behavior. We addressed this issue for an orientation task where walking blowflies approached a black vertical bar. The visual stimulus was stationary, or either the bar or the background moved horizontally. The stride-coupled gaze shifts of flies walking toward the bar had similar amplitudes under all visual conditions tested. This finding indicates that these shifts are an inherent feature of walking, which are not even compensated during a visual goal fixation task. By contrast, approaching flies showed a frequent stop-and-go behavior that was affected by the stimulus conditions. As sustained image rotations may impair distance estimation during walking, we propose a hypothesis that explains how rotation-independent translatory image flow containing distance information can be determined. The algorithm proposed works without requiring differentiation at the behavioral level of the rotational and translational flow components. By contrast, disentangling both has been proposed to be necessary during flight. By comparing the retinal velocities of the edges of the goal, its rotational image motion component can be removed. Consequently, the expansion velocity of the goal and, thus, its proximity can be extracted, irrespective of distance-independent stride-coupled rotational image shifts.

  19. Assessment of In-Hospital Walking Velocity and Level of Assistance in a Powered Exoskeleton in Persons with Spinal Cord Injury

    PubMed Central

    Yang, Ajax; Asselin, Pierre; Knezevic, Steven; Kornfeld, Stephen

    2015-01-01

    Background: Individuals with spinal cord injury (SCI) often use a wheelchair for mobility due to paralysis. Powered exoskeletal-assisted walking (EAW) provides a modality for walking overground with crutches. Little is known about the EAW velocities and level of assistance (LOA) needed for these devices. Objective: The primary aim was to evaluate EAW velocity, number of sessions, and LOA and the relationships among them. The secondary aims were to report on safety and the qualitative analysis of gait and posture during EAW in a hospital setting. Methods: Twelve individuals with SCI ≥1.5 years who were wheelchair users participated. They wore a powered exoskeleton (ReWalk; ReWalk Robotics, Inc., Marlborough, MA) with Lofstrand crutches to complete 10-meter (10MWT) and 6-minute (6MWT) walk tests. LOA was defined as modified independence (MI), supervision (S), minimal assistance (Min), and moderate assistance (Mod). Best effort EAW velocity, LOA, and observational gait analysis were recorded. Results: Seven of 12 participants ambulated ≥0.40 m/s. Five participants walked with MI, 3 with S, 3 with Min, and 1 with Mod. Significant inverse relationships were noted between LOA and EAW velocity for both 6MWT (Z value = 2.63, Rho = 0.79, P = .0086) and 10MWT (Z value = 2.62, Rho = 0.79, P = .0088). There were 13 episodes of mild skin abrasions. MI and S groups ambulated with 2-point alternating crutch pattern, whereas the Min and Mod groups favored 3-point crutch gait. Conclusion: Seven of 12 individuals studied were able to ambulate at EAW velocities ≥0.40 m/s, which is a velocity that may be conducive to outdoor activity-related community ambulation. The ReWalk is a safe device for in-hospital ambulation. PMID:26364279

  20. Walking dynamics are symmetric (enough)

    PubMed Central

    Ankaralı, M. Mert; Sefati, Shahin; Madhav, Manu S.; Long, Andrew; Bastian, Amy J.; Cowan, Noah J.

    2015-01-01

    Many biological phenomena such as locomotion, circadian cycles and breathing are rhythmic in nature and can be modelled as rhythmic dynamical systems. Dynamical systems modelling often involves neglecting certain characteristics of a physical system as a modelling convenience. For example, human locomotion is frequently treated as symmetric about the sagittal plane. In this work, we test this assumption by examining human walking dynamics around the steady state (limit-cycle). Here, we adapt statistical cross-validation in order to examine whether there are statistically significant asymmetries and, even if so, test the consequences of assuming bilateral symmetry anyway. Indeed, we identify significant asymmetries in the dynamics of human walking, but nevertheless show that ignoring these asymmetries results in a more consistent and predictive model. In general, neglecting evident characteristics of a system can be more than a modelling convenience—it can produce a better model.

  1. Stable walking with asymmetric legs.

    PubMed

    Merker, Andreas; Rummel, Juergen; Seyfarth, Andre

    2011-12-01

    Asymmetric leg function is often an undesired side-effect in artificial legged systems and may reflect functional deficits or variations in the mechanical construction. It can also be found in legged locomotion in humans and animals such as after an accident or in specific gait patterns. So far, it is not clear to what extent differences in the leg function of contralateral limbs can be tolerated during walking or running. Here, we address this issue using a bipedal spring-mass model for simulating walking with compliant legs. With the help of the model, we show that considerable differences between contralateral legs can be tolerated and may even provide advantages to the robustness of the system dynamics. A better understanding of the mechanisms and potential benefits of asymmetric leg operation may help to guide the development of artificial limbs or the design novel therapeutic concepts and rehabilitation strategies.

  2. Lively quantum walks on cycles

    NASA Astrophysics Data System (ADS)

    Sadowski, Przemysław; Miszczak, Jarosław Adam; Ostaszewski, Mateusz

    2016-09-01

    We introduce a family of quantum walks on cycles parametrized by their liveliness, defined by the ability to execute a long-range move. We investigate the behaviour of the probability distribution and time-averaged probability distribution. We show that the liveliness parameter, controlling the magnitude of the additional long-range move, has a direct impact on the periodicity of the limiting distribution. We also show that the introduced model provides a method for network exploration which is robust against trapping.

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

    NASA Technical Reports Server (NTRS)

    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

  4. Cool flame quench distances

    NASA Technical Reports Server (NTRS)

    Ryason, P. R.; Hirsch, E.

    1974-01-01

    The results of a brief experimental investigation are presented which confirm the expectation that cool flame quenching distances should be larger than hot flame quenching distances. It is also discovered that whereas quenching distances for hot flames reach their minimum values near stoichiometric conditions, cool flame quenching distances are least under rich conditions. Rich conditions are well known to favor cool flame formation.

  5. Facilitating Distance Education.

    ERIC Educational Resources Information Center

    Rossman, Mark H., Ed.; Rossman, Maxine E., Ed.

    1995-01-01

    This collection of articles on distance learning reflects the perspectives and concerns of the learner and the facilitator of learning in distance education setting. Eight chapters are included: (1) "The Evolution and Advantages of Distance Education" (John E. Cantelon) traces the history of distance education and demonstrates how it transcends…

  6. Six-Minute Walk Test demonstrates motor fatigue in spinal muscular atrophy

    PubMed Central

    Montes, J.; McDermott, M. P.; Martens, W. B.; Dunaway, S.; Glanzman, A. M.; Riley, S.; Quigley, J.; Montgomery, M. J.; Sproule, D.; Tawil, R.; Chung, W. K.; Darras, B. T.; De Vivo, D. C.; Kaufmann, P.; Finkel, R. S.

    2010-01-01

    Background: In spinal muscular atrophy (SMA), weakness, decreased endurance, and fatigue limit mobility. Scales have been developed to measure function across the wide spectrum of disease severity. However, these scales typically are observer dependent, and scores are based on sums across Likert-scaled items. The Six-Minute Walk Test (6MWT) is an objective, easily administered, and standardized evaluation of functional exercise capacity that has been proven reliable in other neurologic disorders and in children. Methods: To study the performance of the 6MWT in SMA, 18 ambulatory participants were evaluated in a cross-sectional study. Clinical measures were 6MWT, 10-m walk/run, Hammersmith Functional Motor Scale–Expanded (HFMSE), forced vital capacity, and handheld dynamometry. Associations between the 6MWT total distance and other outcomes were analyzed using Spearman correlation coefficients. A paired t test was used to compare the mean distance walked in the first and sixth minutes. Results: The 6MWT was associated with the HFMSE score (r = 0.83, p < 0.0001), 10-m walk/run (r = −0.87, p < 0.0001), and knee flexor strength (r = 0.62, p = 0.01). Gait velocity decreased during successive minutes in nearly all participants. The average first minute distance (57.5 m) was significantly more than the sixth minute distance (48 m) (p = 0.0003). Conclusion: The Six-Minute Walk Test (6MWT) can be safely performed in ambulatory patients with spinal muscular atrophy (SMA), correlates with established outcome measures, and is sensitive to fatigue-related changes. The 6MWT is a promising candidate outcome measure for clinical trials in ambulatory subjects with SMA. GLOSSARY FVC = forced vital capacity; HFMSE = Hammersmith Functional Motor Scale–Expanded; HHD = handheld dynamometry; 6MWT = Six-Minute Walk Test; SMA = spinal muscular atrophy. PMID:20211907

  7. Walkway Length Determination for Steady State Walking in Young and Older Adults

    ERIC Educational Resources Information Center

    Macfarlane, Pamela A.; Looney, Marilyn A.

    2008-01-01

    The primary purpose of this study was to determine acceleration (AC) and deceleration (DC) distances that would accommodate young and older adults walking at their preferred and fast speeds. A secondary purpose was to determine the minimal walkway length needed to record six steady state (SS) steps (three full gait cycles) for younger and older…

  8. Feasibility and Reliability of Two Different Walking Tests in People with Severe Intellectual and Sensory Disabilities

    ERIC Educational Resources Information Center

    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 severe multiple disabilities, with Gross Motor…

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

    PubMed

    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. PMID:27402559

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

    PubMed

    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.

  11. Body stability and muscle and motor cortex activity during walking with wide stance

    PubMed Central

    Farrell, Brad J.; Bulgakova, Margarita A.; Beloozerova, Irina N.; Sirota, Mikhail G.

    2014-01-01

    Biomechanical and neural mechanisms of balance control during walking are still poorly understood. In this study, we examined the body dynamic stability, activity of limb muscles, and activity of motor cortex neurons [primarily pyramidal tract neurons (PTNs)] in the cat during unconstrained walking and walking with a wide base of support (wide-stance walking). By recording three-dimensional full-body kinematics we found for the first time that during unconstrained walking the cat is dynamically unstable in the forward direction during stride phases when only two diagonal limbs support the body. In contrast to standing, an increased lateral between-paw distance during walking dramatically decreased the cat's body dynamic stability in double-support phases and prompted the cat to spend more time in three-legged support phases. Muscles contributing to abduction-adduction actions had higher activity during stance, while flexor muscles had higher activity during swing of wide-stance walking. The overwhelming majority of neurons in layer V of the motor cortex, 82% and 83% in the forelimb and hindlimb representation areas, respectively, were active differently during wide-stance walking compared with unconstrained condition, most often by having a different depth of stride-related frequency modulation along with a different mean discharge rate and/or preferred activity phase. Upon transition from unconstrained to wide-stance walking, proximal limb-related neuronal groups subtly but statistically significantly shifted their activity toward the swing phase, the stride phase where most of body instability occurs during this task. The data suggest that the motor cortex participates in maintenance of body dynamic stability during locomotion. PMID:24790167

  12. Body stability and muscle and motor cortex activity during walking with wide stance.

    PubMed

    Farrell, Brad J; Bulgakova, Margarita A; Beloozerova, Irina N; Sirota, Mikhail G; Prilutsky, Boris I

    2014-08-01

    Biomechanical and neural mechanisms of balance control during walking are still poorly understood. In this study, we examined the body dynamic stability, activity of limb muscles, and activity of motor cortex neurons [primarily pyramidal tract neurons (PTNs)] in the cat during unconstrained walking and walking with a wide base of support (wide-stance walking). By recording three-dimensional full-body kinematics we found for the first time that during unconstrained walking the cat is dynamically unstable in the forward direction during stride phases when only two diagonal limbs support the body. In contrast to standing, an increased lateral between-paw distance during walking dramatically decreased the cat's body dynamic stability in double-support phases and prompted the cat to spend more time in three-legged support phases. Muscles contributing to abduction-adduction actions had higher activity during stance, while flexor muscles had higher activity during swing of wide-stance walking. The overwhelming majority of neurons in layer V of the motor cortex, 82% and 83% in the forelimb and hindlimb representation areas, respectively, were active differently during wide-stance walking compared with unconstrained condition, most often by having a different depth of stride-related frequency modulation along with a different mean discharge rate and/or preferred activity phase. Upon transition from unconstrained to wide-stance walking, proximal limb-related neuronal groups subtly but statistically significantly shifted their activity toward the swing phase, the stride phase where most of body instability occurs during this task. The data suggest that the motor cortex participates in maintenance of body dynamic stability during locomotion.

  13. The QWalk simulator of quantum walks

    NASA Astrophysics Data System (ADS)

    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

  14. Energetic and biomechanical constraints on animal migration distance.

    PubMed

    Hein, Andrew M; Hou, Chen; Gillooly, James F

    2012-02-01

    Animal migration is one of the great wonders of nature, but the factors that determine how far migrants travel remain poorly understood. We present a new quantitative model of animal migration and use it to describe the maximum migration distance of walking, swimming and flying migrants. The model combines biomechanics and metabolic scaling to show how maximum migration distance is constrained by body size for each mode of travel. The model also indicates that the number of body lengths travelled by walking and swimming migrants should be approximately invariant of body size. Data from over 200 species of migratory birds, mammals, fish, and invertebrates support the central conclusion of the model - that body size drives variation in maximum migration distance among species through its effects on metabolism and the cost of locomotion. The model provides a new tool to enhance general understanding of the ecology and evolution of migration. PMID:22093885

  15. The long road of pain: chronic pain increases perceived distance.

    PubMed

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

    2009-01-01

    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 compared with a control group. These results indicate the physical, and perhaps emotional, costs of chronic pain affect spatial perceptions.

  16. Energetic and biomechanical constraints on animal migration distance.

    PubMed

    Hein, Andrew M; Hou, Chen; Gillooly, James F

    2012-02-01

    Animal migration is one of the great wonders of nature, but the factors that determine how far migrants travel remain poorly understood. We present a new quantitative model of animal migration and use it to describe the maximum migration distance of walking, swimming and flying migrants. The model combines biomechanics and metabolic scaling to show how maximum migration distance is constrained by body size for each mode of travel. The model also indicates that the number of body lengths travelled by walking and swimming migrants should be approximately invariant of body size. Data from over 200 species of migratory birds, mammals, fish, and invertebrates support the central conclusion of the model - that body size drives variation in maximum migration distance among species through its effects on metabolism and the cost of locomotion. The model provides a new tool to enhance general understanding of the ecology and evolution of migration.

  17. Training for Distance Teaching through Distance Learning.

    ERIC Educational Resources Information Center

    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)

  18. Stereo vision with distance and gradient recognition

    NASA Astrophysics Data System (ADS)

    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.

  19. Quantum walks with infinite hitting times

    SciTech Connect

    Krovi, Hari; Brun, Todd A.

    2006-10-15

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

  20. Does walking change the Romberg sign?

    PubMed

    Findlay, Gordon F G; Balain, Birender; Trivedi, Jayesh M; Jaffray, David C

    2009-10-01

    The Romberg sign helps demonstrate loss of postural control as a result of severely compromised proprioception. There is still no standard approach to applying the Romberg test in clinical neurology and the criteria for and interpretation of an abnormal result continue to be debated. The value of this sign and its adaptation when walking was evaluated. Detailed clinical examination of 50 consecutive patients of cervical myelopathy was performed prospectively. For the walking Romberg sign, patients were asked to walk 5 m with their eyes open. This was repeated with their eyes closed. Swaying, feeling of instability or inability to complete the walk with eyes closed was interpreted as a positive walking Romberg sign. This test was compared to common clinical signs to evaluate its relevance. Whilst the Hoffman's reflex (79%) was the most prevalent sign seen, the walking Romberg sign was actually present in 74.5% of the cases. The traditional Romberg test was positive in 17 cases and 16 of these had the walking Romberg positive as well. Another 21 patients had a positive walking Romberg test. Though not statistically significant, the mean 30 m walking times were slower in patients with traditional Romberg test than in those with positive walking Romberg test and fastest in those with neither of these tests positive. The combination of either Hoffman's reflex and/or walking Romberg was positive in 96% of patients. The walking Romberg sign is more useful than the traditional Romberg test as it shows evidence of a proprioceptive gait deficit in significantly more patients with cervical myelopathy than is found on conventional neurological examination. The combination of Hoffman's reflex and walking Romberg sign has a potential as useful screening tests to detect clinically significant cervical myelopathy. PMID:19387702

  1. Neural Basis of Stimulus-Angle-Dependent Motor Control of Wind-Elicited Walking Behavior in the Cricket Gryllus bimaculatus

    PubMed Central

    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

  2. Walking capabilities of Gregor controlled through Walknet

    NASA Astrophysics Data System (ADS)

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

    2007-05-01

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

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed

    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.

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

    SciTech Connect

    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.

  6. Rhythm analysis of orthogonal signals from human walking.

    PubMed

    Ekimov, Alexander; Sabatier, James M

    2011-03-01

    In physical terms, periodic movements of a human body resulting from walking produce a pulse sequence with repetition time T(1) (instant cadence frequency, 1/T(1)) and duration time T(2). Footstep forces generate periodic T(1) broadband seismic and sound signals due to the dynamic forces between the foot and the ground/floor with duration time T(2), which is equal to the time interval for a single footstep from heel strike to toe slap and weight transfer. In a human gait study (for normal speeds of walking), T(1) was detected as 0.5-0.69 s and double limb support takes up about 12% of the gait cycle (2T(1)), so T(2) is greater than 0.12-0.17 s. Short range (of about 50 m) signatures for 30 humans were recorded simultaneously by four orthogonal sensor types at two locations. The sensor types were active Doppler sonar/radar and passive seismic/acoustics. Analysis of signals from these four sensors collected for walking humans showed temporal synchronization and stability of the cadence frequencies, and the cadence frequency from each sensor was equivalent. The time delay between signals from these sensors due to the differences in speeds of propagation for seismic, sound, and electromagnetic waves allows calculation of the distance from a walker to the sensor suite. PMID:21428494

  7. Treacherous Pavements: Paving Slab Patterns Modify Intended Walking Directions.

    PubMed

    Leonards, Ute; Fennell, John G; Oliva, Gaby; Drake, Alex; Redmill, David W

    2015-01-01

    Current understanding in locomotion research is that, for humans, navigating natural environments relies heavily on visual input; in contrast, walking on even ground in man-made obstacle and hazard-free environments is so highly automated that visual information derived from floor patterns should not affect locomotion and in particular have no impact on the direction of travel. The vision literature on motion perception would suggest otherwise; specifically that oblique floor patterns may induce substantial veering away from the intended direction of travel due to the so-called aperture problem. Here, we tested these contrasting predictions by letting participants walk over commonly encountered floor patterns (paving slabs) and investigating participants' ability to walk "straight ahead" for different pattern orientations. We show that, depending on pattern orientation, participants veered considerably over the measured travel distance (up to 8% across trials), in line with predictions derived from the literature on motion perception. We argue that these findings are important to the study of locomotion, and, if also observed in real world environments, might have implications for architectural design.

  8. Humans Can Continuously Optimize Energetic Cost during Walking.

    PubMed

    Selinger, Jessica C; O'Connor, Shawn M; Wong, Jeremy D; Donelan, J Maxwell

    2015-09-21

    People prefer to move in ways that minimize their energetic cost. For example, people tend to walk at a speed that minimizes energy use per unit distance and, for that speed, they select a step frequency that makes walking less costly. Although aspects of this preference appear to be established over both evolutionary and developmental timescales, it remains unclear whether people can also optimize energetic cost in real time. Here we show that during walking, people readily adapt established motor programs to minimize energy use. To accomplish this, we used robotic exoskeletons to shift people's energetically optimal step frequency to frequencies higher and lower than normally preferred. In response, we found that subjects adapted their step frequency to converge on the new energetic optima within minutes and in response to relatively small savings in cost (<5%). When transiently perturbed from their new optimal gait, subjects relied on an updated prediction to rapidly re-converge within seconds. Our collective findings indicate that energetic cost is not just an outcome of movement, but also plays a central role in continuously shaping it.

  9. Rhythm analysis of orthogonal signals from human walking.

    PubMed

    Ekimov, Alexander; Sabatier, James M

    2011-03-01

    In physical terms, periodic movements of a human body resulting from walking produce a pulse sequence with repetition time T(1) (instant cadence frequency, 1/T(1)) and duration time T(2). Footstep forces generate periodic T(1) broadband seismic and sound signals due to the dynamic forces between the foot and the ground/floor with duration time T(2), which is equal to the time interval for a single footstep from heel strike to toe slap and weight transfer. In a human gait study (for normal speeds of walking), T(1) was detected as 0.5-0.69 s and double limb support takes up about 12% of the gait cycle (2T(1)), so T(2) is greater than 0.12-0.17 s. Short range (of about 50 m) signatures for 30 humans were recorded simultaneously by four orthogonal sensor types at two locations. The sensor types were active Doppler sonar/radar and passive seismic/acoustics. Analysis of signals from these four sensors collected for walking humans showed temporal synchronization and stability of the cadence frequencies, and the cadence frequency from each sensor was equivalent. The time delay between signals from these sensors due to the differences in speeds of propagation for seismic, sound, and electromagnetic waves allows calculation of the distance from a walker to the sensor suite.

  10. Random walk with random resetting to the maximum position

    NASA Astrophysics Data System (ADS)

    Majumdar, Satya N.; Sabhapandit, Sanjib; Schehr, Grégory

    2015-11-01

    We study analytically a simple random walk model on a one-dimensional lattice, where at each time step the walker resets to the maximum of the already visited positions (to the rightmost visited site) with a probability r , and with probability (1 -r ) , it undergoes symmetric random walk, i.e., it hops to one of its neighboring sites, with equal probability (1 -r )/2 . For r =0 , it reduces to a standard random walk whose typical distance grows as √{n } for large n . In the presence of a nonzero resetting rate 0

  11. Random walk with random resetting to the maximum position.

    PubMed

    Majumdar, Satya N; Sabhapandit, Sanjib; Schehr, Grégory

    2015-11-01

    We study analytically a simple random walk model on a one-dimensional lattice, where at each time step the walker resets to the maximum of the already visited positions (to the rightmost visited site) with a probability r, and with probability (1-r), it undergoes symmetric random walk, i.e., it hops to one of its neighboring sites, with equal probability (1-r)/2. For r=0, it reduces to a standard random walk whose typical distance grows as √n for large n. In the presence of a nonzero resetting rate 0

  12. Quantum walks driven by many coins

    SciTech Connect

    Brun, Todd A.; Ambainis, Andris; Carteret, Hilary A.

    2003-05-01

    Quantum random walks have been much studied recently, largely due to their highly nonclassical behavior. In this paper, we study one possible route to classical behavior for the discrete quantum random walk on the line: the use of multiple quantum 'coins' (or more generally, coins of higher dimension) in order to diminish the effects of interference between paths. We find solutions to this system in terms of the single-coin random walk, and compare the asymptotic limit of these solutions to numerical simulations. We find exact analytical expressions for the time dependence of the first two moments, and show that in the long-time limit the ''quantum-mechanical'' behavior of the one-coin walk persists, even if each coin is flipped only twice. We further show that this is generic for a very broad class of possible walks, and that this behavior disappears only in the limit of a new coin for every step of the walk.

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

    PubMed

    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.

  14. A 2-km walking test for assessing the cardiorespiratory fitness of healthy adults.

    PubMed

    Oja, P; Laukkanen, R; Pasanen, M; Tyry, T; Vuori, I

    1991-08-01

    A simple walking test was developed with 159 (females = 80, males = 79) healthy 20-65-year-old subjects. All the subjects first walked the distances of 1.0, 1.5 and 2.0 km on a flat dirt road. Half of the participants were tested in the laboratory for maximal oxygen uptake (VO2max), and the 2-km test was repeated again twice. In a comparison of the three distances, the 2-km test was repeatable, the most preferable subjectively and the most accurate in predicting VO2max. A sex-specific prediction model including walking time, heart rate at the end of the walk, age and body mass index predicted 73-75% of the variance in VO2max (ml.kg-1.min-1) and that with body weight 66-76%, with a standard error of estimate of the order of 9-15% of the mean. The cross-validation of the models yielded reasonable accuracy in obese men and women and in moderately active men, and less accuracy in moderately active women and highly active men. These results suggest that a fast 2-km walk supplemented with simple measurements is a feasible and accurate alternative for determining the cardiorespiratory fitness of healthy adults.

  15. Continuous limit of discrete quantum walks

    NASA Astrophysics Data System (ADS)

    M N, Dheeraj; Brun, Todd A.

    2015-06-01

    Quantum walks can be defined in two quite distinct ways: discrete-time and continuous-time quantum walks (DTQWs and CTQWs). For classical random walks, there is a natural sense in which continuous-time walks are a limit of discrete-time walks. Quantum mechanically, in the discrete-time case, an additional "coin space" must be appended for the walk to have nontrivial time evolution. Continuous-time quantum walks, however, have no such constraints. This means that there is no completely straightforward way to treat a CTQW as a limit of a DTQW, as can be done in the classical case. Various approaches to this problem have been taken in the past. We give a construction for walks on d -regular, d -colorable graphs when the coin flip operator is Hermitian: from a standard DTQW we construct a family of discrete-time walks with a well-defined continuous-time limit on a related graph. One can think of this limit as a "coined" continuous-time walk. We show that these CTQWs share some properties with coined DTQWs. In particular, we look at a spatial search by a DTQW over the two-dimensional (2D) torus (a grid with periodic boundary conditions) of size √{N }×√{N } , where it was shown that a coined DTQW can search in time O (√{N }logN ) , but a standard CTQW takes Ω (N ) time to search for a marked element. The continuous limit of the DTQW search over the 2D torus exhibits the O (√{N }logN ) scaling, like the coined walk it is derived from. We also look at the effects of graph symmetry on the limiting walk, and show that the properties are similar to those of the DTQW as shown in Krovi and Brun, Phys. Rev. A 75, 062332 (2007), 10.1103/PhysRevA.75.062332.

  16. Gaitography applied to prosthetic walking.

    PubMed

    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.

  17. 10 CFR 431.302 - Definitions concerning walk-in coolers and walk-in freezers.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... FOR CERTAIN COMMERCIAL AND INDUSTRIAL EQUIPMENT Walk-in Coolers and Walk-in Freezers § 431.302...; however the terms do not include products designed and marketed exclusively for medical, scientific,...

  18. Walking and Cycling in the United States, 2001–2009: Evidence From the National Household Travel Surveys

    PubMed Central

    Buehler, Ralph; Merom, Dafna; Bauman, Adrian

    2011-01-01

    Objectives. To assess changes in walking and cycling in the United States between 2001 and 2009. Methods. The 2001 and 2009 National Household Travel Surveys were used to compute the frequency, duration, and distance of walking and cycling per capita. The population-weighted person and trip files were merged to calculate the prevalence of any walking and cycling and of walking and cycling at least 30 minutes per day. Results. The average American made 17 more walk trips in 2009 than in 2001, covering 9 more miles per year, compared with only 2 more bike trips, and 5 more miles cycling. At the population level, the prevalence of “any walking” remained unchanged (about 18%), whereas walking at least 30 minutes per day increased from 7.2% to 8.0%. The prevalence of “any cycling” and cycling 30 minutes per day remained unchanged (1.7% and 0.9%, respectively). Active travel declined for women, children, and seniors, but increased among men, the middle aged, employed, well-educated, and persons without a car. Conclusions. Walking increased slightly, whereas cycling levels stagnated, and the overall prevalence of active travel remained low. Improved infrastructure for walking and cycling must be combined with programs to encourage active travel among more groups, especially children, seniors, and women. PMID:21551387

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

    PubMed

    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.

  20. Visual Acuity During Treadmill Walking

    NASA Technical Reports Server (NTRS)

    Peters, B. T.; Brady, R.; vanEmmerik, R. E. A.; Bloomberg, Jacob J.

    2006-01-01

    An awareness of the physical world is essential for successful navigation through the environment. Vision is the means by which this awareness is made possible for most people. However, without adequate compensation, the movements of the body during walking could impair vision. Previous research has shown how the eyes, head and trunk movements are coordinated to provide the compensation necessary for clear vision, but the overall effectiveness of these coordinated movements is unknown. The goal of the research presented here was to provide a direct measure of visual performance during locomotion, while also investigating the degree to which coordinated head and body movements can be altered to facilitate the goal of seeing clearly.

  1. Head perturbations during walking while viewing a head-fixed target

    NASA Technical Reports Server (NTRS)

    Das, Vallabh E.; Zivotofsky, Ari Z.; Discenna, Alfred O.; Leigh, R. John

    1995-01-01

    Inexpensive, head-fixed computer displays are now available that subjects can wear during locomotion. Our hypothesis is that viewing a head-fixed visual display will change the character- istics of rotational head perturbations during natural walking. Using a 3-axis angular rate sensor, we measured head rotations during natural or treadmill walking, in 10 normal subjects and 2 patients with deficient vestibular function, as they attempted to view (1) a stationary target at optical infinity; and (2) a target at a distance of 20 cm rigidly attached to the head. Normal subjects and patients showed no significant change in the predominant frequency of head rotations in any plane (ranging 0.7-5.7 Hz) during the two different viewing tasks. Mean peak head velocities also showed no difference during the two viewing conditions except in the yaw plane, in which values were greater while viewing the near target. Predominant frequencies of head rotations were similar in the pitch plane during natural or treadmill walking; however, peak velocities of pitch head rotations were substantially greater during natural walking. One vestibular patient showed modest increases of head velocity during natural walking compared with normal subjects. Rotational head perturbations that occur during natural walking are largely unaffected when subjects view a head-fixed target. There is need to study how such perturbations, which induce vestibular eye movements, affect vision of head-fixed displays.

  2. Flow distances on open flow networks

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

    An open flow network is a weighted directed graph with a source and a sink, depicting flux distributions on networks in the steady state mode 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. An open flow network is different from a closed flow network because it considers the flows from or to the environment (the source and the sink). For instance, in energetic food webs, species obtain energy not only from other species but also from the environment (sunlight), and species also dissipate energy to the environment. Flow distances between any 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. The conventional method for the calculation of the random walk distance on closed flow networks cannot be applied to open flow networks. Therefore, we derive novel explicit expressions for flow distances of open flow networks according to their underlying Markov matrix of the network in this paper. We apply flow distances to two types of empirical open flow networks, including energetic food webs and economic input-output networks. In energetic food webs, we visualize the trophic level of each species and compare flow distances with other distance metrics on the graph. In economic input-output networks, we rank sectors according to their average flow distances and cluster sectors into different industrial groups with strong connections. Other potential applications and mathematical properties are also discussed. To summarize, flow distance is a useful and powerful tool to study open flow systems.

  3. Motor modules in robot-aided walking

    PubMed Central

    2012-01-01

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

  4. How Well Do Random Walks Parallelize?

    NASA Astrophysics Data System (ADS)

    Efremenko, Klim; Reingold, Omer

    A random walk on a graph is a process that explores the graph in a random way: at each step the walk is at a vertex of the graph, and at each step it moves to a uniformly selected neighbor of this vertex. Random walks are extremely useful in computer science and in other fields. A very natural problem that was recently raised by Alon, Avin, Koucky, Kozma, Lotker, and Tuttle (though it was implicit in several previous papers) is to analyze the behavior of k independent walks in comparison with the behavior of a single walk. In particular, Alon et al. showed that in various settings (e.g., for expander graphs), k random walks cover the graph (i.e., visit all its nodes), Ω(k)-times faster (in expectation) than a single walk. In other words, in such cases k random walks efficiently “parallelize” a single random walk. Alon et al. also demonstrated that, depending on the specific setting, this “speedup” can vary from logarithmic to exponential in k.

  5. Random walks with similar transition probabilities

    NASA Astrophysics Data System (ADS)

    Schiefermayr, Klaus

    2003-04-01

    We consider random walks on the nonnegative integers with a possible absorbing state at -1. A random walk is called [alpha]-similar to a random walk if there exist constants Cij such that for the corresponding n-step transition probabilities , i,j[greater-or-equal, slanted]0, hold. We give necessary and sufficient conditions for the [alpha]-similarity of two random walks both in terms of the parameters and in terms of the corresponding spectral measures which appear in the spectral representation of the n-step transition probabilities developed by Karlin and McGregor.

  6. The Recovery of Walking in Stroke Patients: A Review

    ERIC Educational Resources Information Center

    Jang, Sung Ho

    2010-01-01

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

  7. Lateral optic flow does not influence distance estimation in the desert ant Cataglyphis fortis.

    PubMed

    Ronacher, B; Gallizzi, K; Wohlgemuth, S; Wehner, R

    2000-04-01

    The present account answers the question of whether desert ants (Cataglyphis fortis) gauge the distance they have travelled by using self-induced lateral optic-flow parameters, as has been described for bees. The ants were trained to run to a distant food source within a channel whose walls were covered with black-and-white gratings. From the food source, they were transferred to test channels of double or half the training width, and the distance they travelled before searching for home and their walking speeds were recorded. Since the animals experience different motion parallax cues when walking in the broader or narrower channels, the optic-flow hypothesis predicted that the ants would walk faster and further in the broader channels, but more slowly and less far in the narrower channels. In contrast to this expectation, neither the walking speeds nor the searching distances depended on the width or height of the channels or on the pattern wavelengths. Even when ventral-field visual cues were excluded by covering the eyes with light-tight paint, the ants were not influenced by lateral optic flow-field cues. Hence, walking desert ants do not depend on self-induced visual flow-field cues in gauging the distance they have travelled, as do flying honeybees, but can measure locomotor distance exclusively by idiothetic means. PMID:10708632

  8. Lateral optic flow does not influence distance estimation in the desert ant Cataglyphis fortis.

    PubMed

    Ronacher, B; Gallizzi, K; Wohlgemuth, S; Wehner, R

    2000-04-01

    The present account answers the question of whether desert ants (Cataglyphis fortis) gauge the distance they have travelled by using self-induced lateral optic-flow parameters, as has been described for bees. The ants were trained to run to a distant food source within a channel whose walls were covered with black-and-white gratings. From the food source, they were transferred to test channels of double or half the training width, and the distance they travelled before searching for home and their walking speeds were recorded. Since the animals experience different motion parallax cues when walking in the broader or narrower channels, the optic-flow hypothesis predicted that the ants would walk faster and further in the broader channels, but more slowly and less far in the narrower channels. In contrast to this expectation, neither the walking speeds nor the searching distances depended on the width or height of the channels or on the pattern wavelengths. Even when ventral-field visual cues were excluded by covering the eyes with light-tight paint, the ants were not influenced by lateral optic flow-field cues. Hence, walking desert ants do not depend on self-induced visual flow-field cues in gauging the distance they have travelled, as do flying honeybees, but can measure locomotor distance exclusively by idiothetic means.

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

    PubMed

    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.

  10. Going the Distance

    ERIC Educational Resources Information Center

    Waters, John K.

    2012-01-01

    Whoever said "Distance education begins in the 10th row" was taking a jab at the comatose kids at the back of his classroom, but the comment also taps into the old image of distance learners as disengaged themselves. That was then. Today, distance-learning programs are booming, in part due to demographic realities but also because recent advances…

  11. Foundations of Distance Education.

    ERIC Educational Resources Information Center

    Morabito, Margaret Gorts

    The foundations, development, and delivery of distance education were examined through a literature review and first-hand experience in administration and teaching in an international online school. The evolution of distance education was traced from the 1800s, when it was a print-based method of instruction conducted at a distance, through the…

  12. Distance Education Research.

    ERIC Educational Resources Information Center

    Curran, Chris

    1983-01-01

    Reviews six papers from the Open University Distance Education Research Group which cover the following topics: the credibility of distance education, admission systems, distance methods in adult basic education, the Universidad Estatal a Distancia (Costa Rica), Radio Ecca (Canary Islands), and the Open University (Great Britain). (EAO)

  13. Making Distance Education Borderless.

    ERIC Educational Resources Information Center

    Srisa-An, Wichit

    1997-01-01

    Begins with a tribute to Professor G. Ram Reddy (founder of Indira Gandhi National Open University), then focuses on enhancing the role of open universities in providing borderless distance education. Highlights include the need for open distance-education; philosophy and vision; the distance teaching system; the role of information technology;…

  14. Substantiating Appropriate Motion Capture Techniques for the Assessment of Nordic Walking Gait and Posture in Older Adults.

    PubMed

    Dalton, Christopher M; Nantel, Julie

    2016-05-12

    Nordic walking (NW) has become a safe and simple form of exercise in recent years, and in studying this gait pattern, various data collection techniques have been employed, each with positives and negatives. The aim was to determine the effect of NW on older adult gait and posture and to determine optimal use of different data collection systems in both short and long duration analysis. Gait and posture during NW and normal walking were assessed in 17 healthy older adults (age: 69 ± 7.3). Participants performed two trials of 6 Minute Walk Tests (6MWT) (1 with poles (WP) and 1 without poles (NP)) and 6 trials of a 5m walk (3 WP and 3 NP). Motion was recorded using two systems, a 6-sensor accelerometry system and an 8-camera 3-dimensional motion capture system, in order to quantify spatial-temporal, kinematic, and kinetic parameters. With both systems, participants demonstrated increased stride length and double support and decreased gait speed and cadence WP compared to NP (p <0.05). Also, with motion capture, larger single support time was found WP (p <0.05). With 3-D capture, smaller hip power generation and moments of force were found at heel contact and pre-swing as well as smaller knee power absorption at heel contact, pre-swing, and terminal swing WP compared to NP, when assessed over one cycle (p <0.05). Also, WP yielded smaller moments of force at heel contact and terminal swing along with larger moments at mid-stance of a gait cycle (p <0.05). No changes were found for posture. NW seems appropriate for promoting a normal gait pattern in older adults. Three-dimensional motion capture should primarily be used during short duration gait analysis (i.e. single gait cycle), while accelerometry systems should be primarily employed in instances requiring longer duration analysis such as during the 6MWT.

  15. Substantiating Appropriate Motion Capture Techniques for the Assessment of Nordic Walking Gait and Posture in Older Adults.

    PubMed

    Dalton, Christopher M; Nantel, Julie

    2016-01-01

    Nordic walking (NW) has become a safe and simple form of exercise in recent years, and in studying this gait pattern, various data collection techniques have been employed, each with positives and negatives. The aim was to determine the effect of NW on older adult gait and posture and to determine optimal use of different data collection systems in both short and long duration analysis. Gait and posture during NW and normal walking were assessed in 17 healthy older adults (age: 69 ± 7.3). Participants performed two trials of 6 Minute Walk Tests (6MWT) (1 with poles (WP) and 1 without poles (NP)) and 6 trials of a 5m walk (3 WP and 3 NP). Motion was recorded using two systems, a 6-sensor accelerometry system and an 8-camera 3-dimensional motion capture system, in order to quantify spatial-temporal, kinematic, and kinetic parameters. With both systems, participants demonstrated increased stride length and double support and decreased gait speed and cadence WP compared to NP (p <0.05). Also, with motion capture, larger single support time was found WP (p <0.05). With 3-D capture, smaller hip power generation and moments of force were found at heel contact and pre-swing as well as smaller knee power absorption at heel contact, pre-swing, and terminal swing WP compared to NP, when assessed over one cycle (p <0.05). Also, WP yielded smaller moments of force at heel contact and terminal swing along with larger moments at mid-stance of a gait cycle (p <0.05). No changes were found for posture. NW seems appropriate for promoting a normal gait pattern in older adults. Three-dimensional motion capture should primarily be used during short duration gait analysis (i.e. single gait cycle), while accelerometry systems should be primarily employed in instances requiring longer duration analysis such as during the 6MWT. PMID:27214263

  16. Spatial search by quantum walk

    SciTech Connect

    Childs, Andrew M.; Goldstone, Jeffrey

    2004-08-01

    Grover's quantum search algorithm provides a way to speed up combinatorial search, but is not directly applicable to searching a physical database. Nevertheless, Aaronson and Ambainis showed that a database of N items laid out in d spatial dimensions can be searched in time of order {radical}(N) for d>2, and in time of order {radical}(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 {radical}(N) speedup can also be achieved on the hypercube. We show that full {radical}(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 {radical}(N) poly(log N), and in d<4, the algorithm does not provide substantial speedup.

  17. Cochlea segmentation using iterated random walks with shape prior

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed Central

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

    2016-01-01

    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. PMID:27598171

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

    PubMed

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

    2016-01-01

    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. PMID:27598171

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

    PubMed

    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.

  1. Web-Based Walk-Throughs

    ERIC Educational Resources Information Center

    Granada, Janet; Vriesenga, Michael

    2008-01-01

    Walk-through classroom observations are an effective way for principals to learn about and shape instruction and culture in their schools. But many principals don't use walk-throughs to their potential because of the time it takes to store, process, analyze, and give feedback. To facilitate the use of this valuable observation tool, the Kentucky…

  2. Open Quantum Walks: a short introduction

    NASA Astrophysics Data System (ADS)

    Sinayskiy, Ilya; Petruccione, Francesco

    2013-06-01

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

  3. Brownian Optimal Stopping and Random Walks

    SciTech Connect

    Lamberton, D.

    2002-06-05

    One way to compute the value function of an optimal stopping problem along Brownian paths consists of approximating Brownian motion by a random walk. We derive error estimates for this type of approximation under various assumptions on the distribution of the approximating random walk.

  4. Welly-Walks for Science Learning

    ERIC Educational Resources Information Center

    Fradley, Carol

    2006-01-01

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

  5. Cognitive Resource Demands of Redirected Walking.

    PubMed

    Bruder, Gerd; Lubas, Paul; Steinicke, Frank

    2015-04-01

    Redirected walking allows users to walk through a large-scale immersive virtual environment (IVE) while physically remaining in a reasonably small workspace. Therefore, manipulations are applied to virtual camera motions so that the user's self-motion in the virtual world differs from movements in the real world. Previous work found that the human perceptual system tolerates a certain amount of inconsistency between proprioceptive, vestibular and visual sensation in IVEs, and even compensates for slight discrepancies with recalibrated motor commands. Experiments showed that users are not able to detect an inconsistency if their physical path is bent with a radius of at least 22 meters during virtual straightforward movements. If redirected walking is applied in a smaller workspace, manipulations become noticeable, but users are still able to move through a potentially infinitely large virtual world by walking. For this semi-natural form of locomotion, the question arises if such manipulations impose cognitive demands on the user, which may compete with other tasks in IVEs for finite cognitive resources. In this article we present an experiment in which we analyze the mutual influence between redirected walking and verbal as well as spatial working memory tasks using a dual-tasking method. The results show an influence of redirected walking on verbal as well as spatial working memory tasks, and we also found an effect of cognitive tasks on walking behavior. We discuss the implications and provide guidelines for using redirected walking in virtual reality laboratories. PMID:26357104

  6. The excited random walk in one dimension

    NASA Astrophysics Data System (ADS)

    Antal, T.; Redner, S.

    2005-03-01

    We study the excited random walk, in which a walk that is at a site that contains cookies eats one cookie and then hops to the right with probability p and to the left with probability q = 1 - p. If the walk hops onto an empty site, there is no bias. For the 1-excited walk on the half-line (one cookie initially at each site), the probability of first returning to the starting point at time t scales as t-(2-p). Although the average return time to the origin is infinite for all p, the walk eats, on average, only a finite number of cookies until this first return when p < 1/2. For the infinite line, the probability distribution for the 1-excited walk has an unusual anomaly at the origin. The positions of the leftmost and rightmost uneaten cookies can be accurately estimated by probabilistic arguments and their corresponding distributions have power-law singularities. The 2-excited walk on the infinite line exhibits peculiar features in the regime p > 3/4, where the walk is transient, including a mean displacement that grows as tν, with \

  7. Excited Random Walk in One Dimension

    NASA Astrophysics Data System (ADS)

    Antal, Tibor

    2005-03-01

    We study the k-excited random walk, in which each site initially contains k cookies, and a random walk that is at a site that contains at least one cookie eats a cookie and then hops to the right with probability p and to the left with probability q=1-p. If the walk hops from an empty site, there is no bias. For the 1-excited walk on the half-line (each site initially contains one cookie), the probability of first returning to the starting point at time t scales as t-1-q. We also derive the probability distribution of the position of the leftmost uneaten cookie in the large time limit. For the infinite line, the probability distribution of the position of the 1-excited walk has an unusual anomaly at the origin and the distributions of positions for the leftmost and rightmost uneaten cookie develop a power-law singularity at the origin. The 2-excited walk on the infinite line exhibits peculiar features in the regime p>3/4, where the walk is transient, including a mean displacement that grows as t^ν, with ν>12 dependent on p, and a breakdown of scaling for the probability distribution of the walk.

  8. Walking in circles: a modelling approach

    PubMed Central

    Maus, Horst-Moritz; Seyfarth, Andre

    2014-01-01

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

  9. Walking in circles: a modelling approach.

    PubMed

    Maus, Horst-Moritz; Seyfarth, Andre

    2014-10-01

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

  10. Cognitive Resource Demands of Redirected Walking.

    PubMed

    Bruder, Gerd; Lubas, Paul; Steinicke, Frank

    2015-04-01

    Redirected walking allows users to walk through a large-scale immersive virtual environment (IVE) while physically remaining in a reasonably small workspace. Therefore, manipulations are applied to virtual camera motions so that the user's self-motion in the virtual world differs from movements in the real world. Previous work found that the human perceptual system tolerates a certain amount of inconsistency between proprioceptive, vestibular and visual sensation in IVEs, and even compensates for slight discrepancies with recalibrated motor commands. Experiments showed that users are not able to detect an inconsistency if their physical path is bent with a radius of at least 22 meters during virtual straightforward movements. If redirected walking is applied in a smaller workspace, manipulations become noticeable, but users are still able to move through a potentially infinitely large virtual world by walking. For this semi-natural form of locomotion, the question arises if such manipulations impose cognitive demands on the user, which may compete with other tasks in IVEs for finite cognitive resources. In this article we present an experiment in which we analyze the mutual influence between redirected walking and verbal as well as spatial working memory tasks using a dual-tasking method. The results show an influence of redirected walking on verbal as well as spatial working memory tasks, and we also found an effect of cognitive tasks on walking behavior. We discuss the implications and provide guidelines for using redirected walking in virtual reality laboratories.

  11. Land Use, Residential Density, and Walking

    PubMed Central

    Rodríguez, Daniel A.; Evenson, Kelly R.; Diez Roux, Ana V.; Brines, Shannon J.

    2009-01-01

    Background The neighborhood environment may play a role in encouraging sedentary patterns, especially for middle-aged and older adults. Purpose Associations between walking and neighborhood population density, retail availability, and land use distribution were examined using data from a cohort of adults aged 45 to 84 years old. Methods Data from a multi-ethnic sample of 5529 adult residents of Baltimore MD, Chicago IL, Forsyth County NC, Los Angeles CA, New York NY, and St. Paul MN, enrolled in the Multi-Ethnic Study of Atherosclerosis in 2000–2002 were linked to secondary land use and population data. Participant reports of access to destinations and stores and objective measures of the percentage of land area in parcels devoted to retail land uses, the population divided by land area in parcels, and the mixture of uses for areas within 200m of each participant's residence were examined. Multinomial logistic regression was used to investigate associations of self-reported and objective neighborhood characteristics with walking. All analyses were conducted in 2008 and 2009. Results After adjustment for individual-level characteristics and neighborhood connectivity, higher density, greater land area devoted to retail uses, and self-reported measures of proximity of destinations and ease of walking to places were each related to walking. In models including all land use measures, population density was positively associated with walking to places and with walking for exercise for more than 90 min/wk both relative to no walking. Availability of retail was associated with walking to places relative to not walking, having a more proportional mix of land uses was associated with walking for exercise for more than 90 min/wk, while self-reported ease of access to places was related to higher levels of exercise walking both relative to not walking. Conclusions Residential density and the presence of retail uses are related to various walking behaviors. Efforts to

  12. Inferring Lévy walks from curved trajectories: A rescaling method

    NASA Astrophysics Data System (ADS)

    Tromer, R. M.; Barbosa, M. B.; Bartumeus, F.; Catalan, J.; da Luz, M. G. E.; Raposo, E. P.; Viswanathan, G. M.

    2015-08-01

    An important problem in the study of anomalous diffusion and transport concerns the proper analysis of trajectory data. The analysis and inference of Lévy walk patterns from empirical or simulated trajectories of particles in two and three-dimensional spaces (2D and 3D) is much more difficult than in 1D because path curvature is nonexistent in 1D but quite common in higher dimensions. Recently, a new method for detecting Lévy walks, which considers 1D projections of 2D or 3D trajectory data, has been proposed by Humphries et al. The key new idea is to exploit the fact that the 1D projection of a high-dimensional Lévy walk is itself a Lévy walk. Here, we ask whether or not this projection method is powerful enough to cleanly distinguish 2D Lévy walk with added curvature from a simple Markovian correlated random walk. We study the especially challenging case in which both 2D walks have exactly identical probability density functions (pdf) of step sizes as well as of turning angles between successive steps. Our approach extends the original projection method by introducing a rescaling of the projected data. Upon projection and coarse-graining, the renormalized pdf for the travel distances between successive turnings is seen to possess a fat tail when there is an underlying Lévy process. We exploit this effect to infer a Lévy walk process in the original high-dimensional curved trajectory. In contrast, no fat tail appears when a (Markovian) correlated random walk is analyzed in this way. We show that this procedure works extremely well in clearly identifying a Lévy walk even when there is noise from curvature. The present protocol may be useful in realistic contexts involving ongoing debates on the presence (or not) of Lévy walks related to animal movement on land (2D) and in air and oceans (3D).

  13. Inferring Lévy walks from curved trajectories: A rescaling method.

    PubMed

    Tromer, R M; Barbosa, M B; Bartumeus, F; Catalan, J; da Luz, M G E; Raposo, E P; Viswanathan, G M

    2015-08-01

    An important problem in the study of anomalous diffusion and transport concerns the proper analysis of trajectory data. The analysis and inference of Lévy walk patterns from empirical or simulated trajectories of particles in two and three-dimensional spaces (2D and 3D) is much more difficult than in 1D because path curvature is nonexistent in 1D but quite common in higher dimensions. Recently, a new method for detecting Lévy walks, which considers 1D projections of 2D or 3D trajectory data, has been proposed by Humphries et al. The key new idea is to exploit the fact that the 1D projection of a high-dimensional Lévy walk is itself a Lévy walk. Here, we ask whether or not this projection method is powerful enough to cleanly distinguish 2D Lévy walk with added curvature from a simple Markovian correlated random walk. We study the especially challenging case in which both 2D walks have exactly identical probability density functions (pdf) of step sizes as well as of turning angles between successive steps. Our approach extends the original projection method by introducing a rescaling of the projected data. Upon projection and coarse-graining, the renormalized pdf for the travel distances between successive turnings is seen to possess a fat tail when there is an underlying Lévy process. We exploit this effect to infer a Lévy walk process in the original high-dimensional curved trajectory. In contrast, no fat tail appears when a (Markovian) correlated random walk is analyzed in this way. We show that this procedure works extremely well in clearly identifying a Lévy walk even when there is noise from curvature. The present protocol may be useful in realistic contexts involving ongoing debates on the presence (or not) of Lévy walks related to animal movement on land (2D) and in air and oceans (3D). PMID:26382383

  14. Efficient quantum walk on a quantum processor.

    PubMed

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

    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 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. PMID:27146471

  15. Efficient quantum walk on a quantum processor

    NASA Astrophysics Data System (ADS)

    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.

  16. Efficient quantum walk on a quantum processor.

    PubMed

    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.

  17. Go naked: diapers affect infant walking.

    PubMed

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

    2012-11-01

    In light of cross-cultural and experimental research highlighting effects of childrearing practices on infant motor skill, we asked whether wearing diapers, a seemingly innocuous childrearing practice, affects infant walking. Diapers introduce bulk between the legs, potentially exacerbating infants' poor balance and wide stance. We show that walking is adversely affected by old-fashioned cloth diapers, and that even modern disposable diapers - habitually worn by most infants in the sample - incur a cost relative to walking naked. Infants displayed less mature gait patterns and more missteps and falls while wearing diapers. Thus, infants' own diapers constitute an ongoing biomechanical perturbation while learning to walk. Furthermore, shifts in diapering practices may have contributed to historical and cross-cultural differences in infant walking. PMID:23106732

  18. Efficient quantum walk on a quantum processor

    PubMed Central

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

    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 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. PMID:27146471

  19. Exploring topological phases with quantum walks

    SciTech Connect

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

    2010-09-15

    The quantum walk was originally proposed as a quantum-mechanical analog of the classical random walk, and has since become a powerful tool in quantum information science. In this paper, we show that discrete-time quantum walks provide a versatile platform for studying topological phases, which are currently the subject of intense theoretical and experimental investigations. In particular, we demonstrate that recent experimental realizations of quantum walks with cold atoms, photons, and ions simulate a nontrivial one-dimensional topological phase. With simple modifications, the quantum walk can be engineered to realize all of the topological phases, which have been classified in one and two dimensions. We further discuss the existence of robust edge modes at phase boundaries, which provide experimental signatures for the nontrivial topological character of the system.

  20. Quantum walks on a random environment

    SciTech Connect

    Yin Yue; Katsanos, D. E.; Evangelou, S. N.

    2008-02-15

    Quantum walks are considered in a one-dimensional random medium characterized by static or dynamic disorder. Quantum interference for static disorder can lead to Anderson localization which completely hinders the quantum walk and it is contrasted with the decoherence effect of dynamic disorder having strength W, where a quantum to classical crossover at time t{sub c}{proportional_to}W{sup -2} transforms the quantum walk into an ordinary random walk with diffusive spreading. We demonstrate these localization and decoherence phenomena in quantum carpets of the observed time evolution, we relate our results to previously studied models of decoherence for quantum walks, and examine in detail a dimer lattice which corresponds to a single qubit subject to randomness.

  1. Segment lengths influence hill walking strategies.

    PubMed

    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. PMID:24968942

  2. The Inter- and Intra-Unit Variability of a Low-Cost GPS Data Logger/Receiver to Study Human Outdoor Walking in View of Health and Clinical Studies

    PubMed Central

    Abraham, Pierre; Noury-Desvaux, Bénédicte; Gernigon, Marie; Mahé, Guillaume; Sauvaget, Thomas; Leftheriotis, Georges; Le Faucheur, Alexis

    2012-01-01

    Purpose The present study evaluates the intra- and inter-unit variability of the GlobalSat® DG100 GPS data logger/receiver (DG100) when estimating outdoor walking distances and speeds. Methods Two experiments were performed using healthy subjects walking on a 400 m outdoor synthetic track. The two experiments consisted of two different outdoor prescribed walking protocols with distances ranging from 50 to 400 m. Experiment 1 examined the intra-unit variability of the DG100 (test-retest reproducibility) when estimating walking distances. Experiment 2 examined the inter-unit variability of four DG100 devices (unit to unit variability) when estimating walking distances and speeds. Results The coefficient of variation [95% confidence interval], for the reliability of estimating walking distances, was 2.8 [2.5–3.2] %. The inter-unit variability among the four DG100 units tested ranged from 2.8 [2.5–3.2] % to 3.9 [3.5–4.4] % when estimating distances and from 2.7 [2.4–3.0] % to 3.8 [3.4–4.2] % when estimating speeds. Conclusion The present study indicates that the DG100, an economical and convenient GPS data logger/receiver, can be reliably used to study human outdoor walking activities in unobstructed conditions. This device let facilitate the use of GPS in studies of health and disease. PMID:22363623

  3. Quantum walking in curved spacetime

    NASA Astrophysics Data System (ADS)

    Arrighi, Pablo; Facchini, Stefano; Forets, Marcelo

    2016-08-01

    A discrete-time quantum walk (QW) is essentially a unitary operator driving the evolution of a single particle on the lattice. Some QWs admit a continuum limit, leading to familiar PDEs (e.g., the Dirac equation). In this paper, we study the continuum limit of a wide class of QWs and show that it leads to an entire class of PDEs, encompassing the Hamiltonian form of the massive Dirac equation in (1+1) curved spacetime. Therefore, a certain QW, which we make explicit, provides us with a unitary discrete toy model of a test particle in curved spacetime, in spite of the fixed background lattice. Mathematically, we have introduced two novel ingredients for taking the continuum limit of a QW, but which apply to any quantum cellular automata: encoding and grouping.

  4. Medical Aspects of Space Walking

    NASA Technical Reports Server (NTRS)

    Musgrave, Story

    1999-01-01

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

  5. Symbolic walk in regular networks

    NASA Astrophysics Data System (ADS)

    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.

  6. The Accuracy of a Simple, Low-Cost GPS Data Logger/Receiver to Study Outdoor Human Walking in View of Health and Clinical Studies

    PubMed Central

    Noury-Desvaux, Bénédicte; Abraham, Pierre; Mahé, Guillaume; Sauvaget, Thomas; Leftheriotis, Georges; Le Faucheur, Alexis

    2011-01-01

    Introduction Accurate and objective measurements of physical activity and lower-extremity function are important in health and disease monitoring, particularly given the current epidemic of chronic diseases and their related functional impairment. Purpose The aim of the present study was to determine the accuracy of a handy (lightweight, small, only one stop/start button) and low-cost (∼$75 with its external antenna) Global Positioning System (GPS) data logger/receiver (the DG100) as a tool to study outdoor human walking in perspective of health and clinical research studies. Methods. Healthy subjects performed two experiments that consisted of different prescribed outdoor walking protocols. Experiment 1. We studied the accuracy of the DG100 for detecting bouts of walking and resting. Experiment 2. We studied the accuracy of the DG100 for estimating distances and speeds of walking. Results Experiment 1. The performance in the detection of bouts, expressed as the percentage of walking and resting bouts that were correctly detected, was 92.4% [95% Confidence Interval: 90.6–94.3]. Experiment 2. The coefficients of variation [95% Confidence Interval] for the accuracy of estimating the distances and speeds of walking were low: 3.1% [2.9–3.3] and 2.8% [2.6–3.1], respectively. Conclusion The DG100 produces acceptable accuracy both in detecting bouts of walking and resting and in estimating distances and speeds of walking during the detected walking bouts. However, before we can confirm that the DG100 can be used to study walking with respect to health and clinical studies, the inter- and intra-DG100 variability should be studied. Trial Registration ClinicalTrials.gov NCT00485147 PMID:21931593

  7. Traversing psychological distance.

    PubMed

    Liberman, Nira; Trope, Yaacov

    2014-07-01

    Traversing psychological distance involves going beyond direct experience, and includes planning, perspective taking, and contemplating counterfactuals. Consistent with this view, temporal, spatial, and social distances as well as hypotheticality are associated, affect each other, and are inferred from one another. Moreover, traversing all distances involves the use of abstraction, which we define as forming a belief about the substitutability for a specific purpose of subjectively distinct objects. Indeed, across many instances of both abstraction and psychological distancing, more abstract constructs are used for more distal objects. Here, we describe the implications of this relation for prediction, choice, communication, negotiation, and self-control. We ask whether traversing distance is a general mental ability and whether distance should replace expectancy in expected-utility theories. PMID:24726527

  8. The Effects of Varying Ankle Foot Orthosis Stiffness on Gait in Children with Spastic Cerebral Palsy Who Walk with Excessive Knee Flexion

    PubMed Central

    Kerkum, Yvette L.; Buizer, Annemieke I.; van den Noort, Josien C.; Becher, Jules G.; Harlaar, Jaap; Brehm, Merel-Anne

    2015-01-01

    Introduction Rigid Ankle-Foot Orthoses (AFOs) are commonly prescribed to counteract excessive knee flexion during the stance phase of gait in children with cerebral palsy (CP). While rigid AFOs may normalize knee kinematics and kinetics effectively, it has the disadvantage of impeding push-off power. A spring-like AFO may enhance push-off power, which may come at the cost of reducing the knee flexion less effectively. Optimizing this trade-off between enhancing push-off power and normalizing knee flexion in stance is expected to maximize gait efficiency. This study investigated the effects of varying AFO stiffness on gait biomechanics and efficiency in children with CP who walk with excessive knee flexion in stance. Fifteen children with spastic CP (11 boys, 10±2 years) were prescribed with a ventral shell spring-hinged AFO (vAFO). The hinge was set into a rigid, or spring-like setting, using both a stiff and flexible performance. At baseline (i.e. shoes-only) and for each vAFO, a 3D-gait analysis and 6-minute walk test with breath-gas analysis were performed at comfortable speed. Lower limb joint kinematics and kinetics were calculated. From the 6-minute walk test, walking speed and the net energy cost were determined. A generalized estimation equation (p<0.05) was used to analyze the effects of different conditions. Compared to shoes-only, all vAFOs improved the knee angle and net moment similarly. Ankle power generation and work were preserved only by the spring-like vAFOs. All vAFOs decreased the net energy cost compared to shoes-only, but no differences were found between vAFOs, showing that the effects of spring-like vAFOs to promote push-off power did not lead to greater reductions in walking energy cost. These findings suggest that, in this specific group of children with spastic CP, the vAFO stiffness that maximizes gait efficiency is primarily determined by its effect on knee kinematics and kinetics rather than by its effect on push-off power. Trial

  9. The Extragalactic Distance Scale

    NASA Astrophysics Data System (ADS)

    Livio, Mario; Donahue, Megan; Panagia, Nino

    1997-07-01

    Participants; Preface; Foreword; Early history of the distance scale problem, S. van den Bergh; Cosmology: From Hubble to HST, M. S. Turner; Age constraints nucleocosmochronology, J. Truran; The ages of globular clusters, P. Demarque; The linearity of the Hubble flow M. Postman; Gravitational lensing and the extragalactic distance scale, R. D. Blandford andT . Kundic; Using the cosmic microwave background to constrain the Hubble constant A. Lasenby and T M. Jones; Cepheids as distance indicators, N. R. Tanvir; The I-band Tully-Fisher relation and the Hubble constant, R. Giovanell; The calibration of type 1a supernovae as standard candles, A. Saha; Focusing in on the Hubble constant, G. A. Tammann & M. Federspiel; Interim report on the calibration of the Tully-Fisher relation in the HST Key Project to measure the Hubble constant, J. Mould et al.; Hubble Space Telescope Key Project on the extragalactic distance scale, W. L. Freedman, B. F. Madore and T R. C. Kennicutt; Novae as distance indicators, M. Livio; Verifying the planetary nebula luminosity function method, G. H. Jacoby; On the possible use of radio supernovae for distance determinations, K. W. Weiler et al.; Post-AGB stars as standard candles, H. Bond; Helium core flash at the tip of the red giant branch: a population II distance indicator, B. F. Madore, W. L. Freedman and T S. Sakai; Globular clusters as distance indicators, B. C. Whitmore; Detached eclipsing binaries as primary distance and age indicators, B. Paczynski; Light echoes: geometric measurement of galaxy distances, W. B. Sparks; The SBF survey of galaxy distances J. L. Tonry; Extragalactic distance scales: The long and short of it, V. Trimble.

  10. Ambulatory estimation of mean step length during unconstrained walking by means of COG accelerometry.

    PubMed

    González, R C; Alvarez, D; López, A M; Alvarez, J C

    2009-12-01

    It has been reported that spatio-temporal gait parameters can be estimated using an accelerometer to calculate the vertical displacement of the body's centre of gravity. This method has the potential to produce realistic ambulatory estimations of those parameters during unconstrained walking. In this work, we want to evaluate the crude estimations of mean step length so obtained, for their possible application in the construction of an ambulatory walking distance measurement device. Two methods have been tested with a set of volunteers in 20 m excursions. Experimental results show that estimations of walking distance can be obtained with sufficient accuracy and precision for most practical applications (errors of 3.66 +/- 6.24 and 0.96 +/- 5.55%), the main difficulty being inter-individual variability (biggest deviations of 19.70 and 15.09% for each estimator). Also, the results indicate that an inverted pendulum model for the displacement during the single stance phase, and a constant displacement per step during double stance, constitute a valid model for the travelled distance with no need of further adjustments. It allows us to explain the main part of the erroneous distance estimations in different subjects as caused by fundamental limitations of the simple inverted pendulum approach. PMID:19408138

  11. Quantitative analysis of human walking trajectory on a circular path in darkness.

    PubMed

    Takei, Y; Grasso, R; Berthoz, A

    1996-01-01

    Thirteen normal (eight young and five older) subjects and a patient who was removed left sided acoustic neurinoma were tested to walk blindfolded along circular paths. They were asked to walk completing two revolutions and to stop when they judged they had returned to the initial position with their head faced to the initial directions. Movements of two markers on the subjects head were recorded by three dimensional motion analyzing system (ELITE system) at 50 Hz which allowed us to measure (a) total walked distance, (b) average radius of the trajectory, and (c) cumulative angle of rotation. Eight young subjects were tested on three circles with radii 0.5, 0.9, and 1.15 m, in two conditions (control, and with mental arythmetic), only to clockwise direction. Five older subjects and a patient were tested on a circle of 0.9 m radius in two conditions, but to both directions, counterclockwise and clockwise. Walked trajectories of young subjects were smooth, whereas those of older subjects tended to be polygonal. Young subjects overshot the ideal distance (6.6%) and ideal radius (9.5%), whereas they undershot the ideal angle (5.1%). There was no effect of circle size or condition on these variables. On the other hand, there was a significant effect of condition on average radius in the older group. The performance of older subjects seemed to be affected by the concurrent mental task. Comparing the counterclockwise walk, the older subjects undershot the turning angle much more than the young subjects which suggest deficits in the vestibular function with aging. The patient showed larger radius and smaller angle while she turned to the healthy side (clockwise) than to the affected side (counterclockwise). Lack of unilateral vestibular information seemed to have affected the circular walking trajectory.

  12. Walking dreams in congenital and acquired paraplegia.

    PubMed

    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.

  13. Walking dreams in congenital and acquired paraplegia.

    PubMed

    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. PMID:21704532

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

    PubMed Central

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

    2011-01-01

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

  15. Hematological and hemorheological Determinants of the Six-Minute Walk Test Performance in Children with Sickle Cell Anemia

    PubMed Central

    Waltz, Xavier; Romana, Marc; Hardy-Dessources, Marie-Dominique; Lamarre, Yann; Divialle-Doumdo, Lydia; Petras, Marie; Tarer, Vanessa; Hierso, Régine; Baltyde, Kizzy-Clara; Tressières, Benoît; Lalanne-Mistrih, Marie-Laure; Maillard, Fréderic; Hue, Olivier; Etienne-Julan, Maryse; Connes, Philippe

    2013-01-01

    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. PMID:24147086

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

    NASA Astrophysics Data System (ADS)

    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.

  17. Usual walking speed and all-cause mortality risk in older people: A systematic review and meta-analysis.

    PubMed

    Liu, Bing; Hu, Xinhua; Zhang, Qiang; Fan, Yichuan; Li, Jun; Zou, Rui; Zhang, Ming; Wang, Xiuqi; Wang, Junpeng

    2016-02-01

    The purpose of this study was to investigate the relationship between slow usual walking speed and all-cause mortality risk in older people by conducting a meta-analysis. We searched through the Pubmed, Embase and Cochrane Library database up to March 2015. Only prospective observational studies that investigating the usual walking speed and all-cause mortality risk in older adulthood approaching age 65 years or more were included. Walking speed should be specifically assessed as a single-item tool over a short distance. Pooled adjusted risk ratio (RR) and 95% confidence interval (CI) were computed for the lowest versus the highest usual walking speed category. A total of 9 studies involving 12,901 participants were included. Meta-analysis with random effect model showed that the pooled adjusted RR of all-cause mortality was 1.89 (95% CI 1.46-2.46) comparing the lowest to the highest usual walk speed. Subgroup analyses indicated that risk of all-cause mortality for slow usual walking speed appeared to be not significant among women (RR 1.45; 95% CI 0.95-2.20). Slow usual walking speed is an independent predictor of all-cause mortality in men but not in women among older adulthood approaching age 65 years or more. PMID:27004653

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

    ERIC Educational Resources Information Center

    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…

  19. Quantum walk public-key cryptographic system

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed

    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.

  1. Quantum Walk Schemes for Universal Quantum Computation

    NASA Astrophysics Data System (ADS)

    Underwood, Michael S.

    Random walks are a powerful tool for the efficient implementation of algorithms in classical computation. Their quantum-mechanical analogues, called quantum walks, hold similar promise. Quantum walks provide a model of quantum computation that has recently been shown to be equivalent in power to the standard circuit model. As in the classical case, quantum walks take place on graphs and can undergo discrete or continuous evolution, though quantum evolution is unitary and therefore deterministic until a measurement is made. This thesis considers the usefulness of continuous-time quantum walks to quantum computation from the perspectives of both their fundamental power under various formulations, and their applicability in practical experiments. In one extant scheme, logical gates are effected by scattering processes. The results of an exhaustive search for single-qubit operations in this model are presented. It is shown that the number of distinct operations increases exponentially with the number of vertices in the scattering graph. A catalogue of all graphs on up to nine vertices that implement single-qubit unitaries at a specific set of momenta is included in an appendix. I develop a novel scheme for universal quantum computation called the discontinuous quantum walk, in which a continuous-time quantum walker takes discrete steps of evolution via perfect quantum state transfer through small 'widget' graphs. The discontinuous quantum-walk scheme requires an exponentially sized graph, as do prior discrete and continuous schemes. To eliminate the inefficient vertex resource requirement, a computation scheme based on multiple discontinuous walkers is presented. In this model, n interacting walkers inhabiting a graph with 2n vertices can implement an arbitrary quantum computation on an input of length n, an exponential savings over previous universal quantum walk schemes. This is the first quantum walk scheme that allows for the application of quantum error correction

  2. Universal computation by multiparticle quantum walk.

    PubMed

    Childs, Andrew M; Gosset, David; Webb, Zak

    2013-02-15

    A quantum walk is a time-homogeneous quantum-mechanical process on a graph defined by analogy to classical random walk. The quantum walker is a particle that moves from a given vertex to adjacent vertices in quantum superposition. We consider a generalization to interacting systems with more than one walker, such as the Bose-Hubbard model and systems of fermions or distinguishable particles with nearest-neighbor interactions, and show that multiparticle quantum walk is capable of universal quantum computation. Our construction could, in principle, be used as an architecture for building a scalable quantum computer with no need for time-dependent control. PMID:23413349

  3. An experimental analysis of human straight walking

    NASA Astrophysics Data System (ADS)

    Li, Tao; Ceccarelli, Marco

    2013-03-01

    In this paper, an experimental analysis of human straight walking has been presented. Experiments on human walking were carried out by using Cassino tracking system which is a passive cable-based measuring system. This system is adopted because it is capable of both pose and wrench measurements with fairly simple monitoring of operation. By using experimental results, trajectories of a human limb extremity and its posture have been analyzed; forces that are exerted against cables by the limb of a person under test have been measured by force sensors as well. Furthermore, by using experimental tests, modeling and characterization of the human straight walking gait have been proposed.

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

    PubMed Central

    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

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

    PubMed

    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.

  6. Validity of a two kilometre walking test for estimating maximal aerobic power in overweight adults.

    PubMed

    Laukkanen, R; Oja, P; Pasanen, M; Vuori, I

    1992-04-01

    In our earlier study a regression model, with heart rate and time in a 2 km fast walk, body mass index (BMI) or weight (kg) and age as explanatory variables, explained 75% of the variation in the VO2max of adults with normal weight. The present study was designed to test whether the prediction model based on a 2km fast walk and simple site measurements is valid in estimating the VO2max of overweight men and women and to compare 1km and 2km test distances. Forty-five women and thirty-two men, BMI 27-40, aged 20-65 years, with no cardiorespiratory or musculoskeletal restrictions for a maximal stress test and fast walk, were studied. The VO2max was determined in an uphill walk to maximal effort on a treadmill. Two walking tests, 1km and 2km, were conducted on a flat dirt road. Heart rate was recorded during the walks, and the mean rate during the last 30 seconds was used in the model. The correlation coefficients between the measured and predicted VO2max in the 2km test were 0.77 for the women and 0.75 for men, corrected for body weight (ml/kg/min), and 0.77 and 0.69 respectively in absolute values (1/min). These results suggest that the 2km walk test previously developed for adults within normal weight limits is a reasonably valid test of the cardiorespiratory fitness of overweight, but otherwise healthy, women and men.

  7. Validation of walk score for estimating neighborhood walkability: an analysis of four US metropolitan areas.

    PubMed

    Duncan, Dustin T; Aldstadt, Jared; Whalen, John; Melly, Steven J; Gortmaker, Steven L

    2011-11-01

    Neighborhood walkability can influence physical activity. We evaluated the validity of Walk Score(®) for assessing neighborhood walkability based on GIS (objective) indicators of neighborhood walkability with addresses from four US metropolitan areas with several street network buffer distances (i.e., 400-, 800-, and 1,600-meters). Address data come from the YMCA-Harvard After School Food and Fitness Project, an obesity prevention intervention involving children aged 5-11 years and their families participating in YMCA-administered, after-school programs located in four geographically diverse metropolitan areas in the US (n = 733). GIS data were used to measure multiple objective indicators of neighborhood walkability. Walk Scores were also obtained for the participant's residential addresses. Spearman correlations between Walk Scores and the GIS neighborhood walkability indicators were calculated as well as Spearman correlations accounting for spatial autocorrelation. There were many significant moderate correlations between Walk Scores and the GIS neighborhood walkability indicators such as density of retail destinations and intersection density (p < 0.05). The magnitude varied by the GIS indicator of neighborhood walkability. Correlations generally became stronger with a larger spatial scale, and there were some geographic differences. Walk Score(®) is free and publicly available for public health researchers and practitioners. Results from our study suggest that Walk Score(®) is a valid measure of estimating certain aspects of neighborhood walkability, particularly at the 1600-meter buffer. As such, our study confirms and extends the generalizability of previous findings demonstrating that Walk Score is a valid measure of estimating neighborhood walkability in multiple geographic locations and at multiple spatial scales.

  8. Comparing four approaches to generalized redirected walking: simulation and live user data.

    PubMed

    Hodgson, Eric; Bachmann, Eric

    2013-04-01

    Redirected walking algorithms imperceptibly rotate a virtual scene and scale movements to guide users of immersive virtual environment systems away from tracking area boundaries. These distortions ideally permit users to explore large and potentially unbounded virtual worlds while walking naturally through a physically limited space. Estimates of the physical space required to perform effective redirected walking have been based largely on the ability of humans to perceive the distortions introduced by redirected walking and have not examined the impact the overall steering strategy used. This work compares four generalized redirected walking algorithms, including Steer-to-Center, Steer-to-Orbit, Steer-to-Multiple-Targets and Steer-to-Multiple+Center. Two experiments are presented based on simulated navigation as well as live-user navigation carried out in a large immersive virtual environment facility. Simulations were conducted with both synthetic paths and previously-logged user data. Primary comparison metrics include mean and maximum distances from the tracking area center for each algorithm, number of wall contacts, and mean rates of redirection. Results indicated that Steer-to-Center out-performed all other algorithms relative to these metrics. Steer-to-Orbit also performed well in some circumstances.

  9. Biomechanics and muscle coordination of human walking: part II: lessons from dynamical simulations and clinical implications.

    PubMed

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

    2003-02-01

    Principles of muscle coordination in gait have been based largely on analyses of body motion, ground reaction force and EMG measurements. However, data from dynamical simulations provide a cause-effect framework for analyzing these measurements; for example, Part I (Gait Posture, in press) of this two-part review described how force generation in a muscle affects the acceleration and energy flow among the segments. This Part II reviews the mechanical and coordination concepts arising from analyses of simulations of walking. Simple models have elucidated the basic multisegmented ballistic and passive mechanics of walking. Dynamical models driven by net joint moments have provided clues about coordination in healthy and pathological gait. Simulations driven by muscle excitations have highlighted the partial stability afforded by muscles with their viscoelastic-like properties and the predictability of walking performance when minimization of metabolic energy per unit distance is assumed. When combined with neural control models for exciting motoneuronal pools, simulations have shown how the integrative properties of the neuro-musculo-skeletal systems maintain a stable gait. Other analyses of walking simulations have revealed how individual muscles contribute to trunk support and progression. Finally, we discuss how biomechanical models and simulations may enhance our understanding of the mechanics and muscle function of walking in individuals with gait impairments.

  10. Postural and dynamic balance while walking in adults with incomplete spinal cord injury.

    PubMed

    Lemay, Jean-François; Duclos, Cyril; Nadeau, Sylvie; Gagnon, Dany; Desrosiers, Émilie

    2014-10-01

    The purpose of this study was to characterize balance in individuals with and without an incomplete spinal cord injury (ISCI) during the single support phase of gait. Thirty-four individuals (17 with a ISCI, 17 able-bodied) walked at their self-selected walking speed. Among those, eighteen individuals (9 with ISCI, 9 able-bodied) with a similar walking speed were also analyzed. Stabilizing and destabilizing forces quantified balance during the single support phase of gait. The biomechanical factors included in the equation of the stabilizing and destabilizing forces served as explanatory factors. Individuals with ISCI had a lower stabilizing force and a higher destabilizing force compared to able-bodied individuals. The main explanatory factors of the forces extracted from the equations were the speed of the center of mass (maximal stabilizing force) and the distance between the center of pressure and the base of support (minimal destabilizing force). Only the minimal destabilizing force was significantly different among subgroups with a similar walking speed. The stabilizing and destabilizing forces suggest that individuals with ISCI were more stable than able-bodied, which was achieved by walking more slowly - which decrease the speed of the center of mass - and keeping the center of pressure away from the margin of the base of support in order to maintain balance within their range of physical ability.

  11. Distance Learning. PEPNet Tipsheet

    ERIC Educational Resources Information Center

    Keefe, Barbara, Comp.

    2002-01-01

    Distance learning is the separation of teacher and student by time and space. Rapid advances in communications technology have allowed distance learning to become one of the fastest-growing trends in higher education. College courses are being delivered across a highway that is global in scope. Today, two thirds of the 4,000 accredited colleges…

  12. Is Distance Learning Transformational?

    ERIC Educational Resources Information Center

    Hoskins, Barbara J.

    2013-01-01

    Is distance learning transformational? The author heard this question posed to a panel of faculty members during Distance Education Week activities. After reflecting upon her own students' reaction to her syllabus, her answer to the question changed from an initial, enthusiastic "yes" to a reflective "maybe," given the most favorable environment.…

  13. Education at a Distance.

    ERIC Educational Resources Information Center

    Maffett, Sheryl Price

    2007-01-01

    Distance learning has been around since the old "course in a box" correspondence classes, but with the advent of sophisticated online course management systems, learning at a distance is contributing to a major paradigm shift in higher education. That shift includes applying corporate concepts to education--students, for example, are "consumers,"…

  14. Biomechanics of Distance Running.

    ERIC Educational Resources Information Center

    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…

  15. Mentoring Distance Learners.

    ERIC Educational Resources Information Center

    Zeeb, Patricia

    2000-01-01

    Defines mentoring, focusing on its use in distance education. Outlines categories of mentoring--traditional, peer, group or team, and online or virtual (telementoring). Discusses mentoring and technological change types of mentors in distance education classes; the role of computer-mediated communications; and decreasing attrition by pairing…

  16. Validation of a Brazilian Portuguese Version of the Walking Estimated-Limitation Calculated by History (WELCH)

    PubMed Central

    Cucato, Gabriel Grizzo; Correia, Marilia de Almeida; Farah, Breno Quintella; Saes, Glauco Fernandes; Lima, Aluísio Henrique de Andrade; Ritti-Dias, Raphael Mendes; Wolosker, Nelson

    2016-01-01

    Background The Walking Estimated-Limitation Calculated by History (WELCH) questionnaire has been proposed to evaluate walking impairment in patients with intermittent claudication (IC), presenting satisfactory psychometric properties. However, a Brazilian Portuguese version of the questionnaire is unavailable, limiting its application in Brazilian patients. Objective To analyze the psychometric properties of a translated Brazilian Portuguese version of the WELCH in Brazilian patients with IC. Methods Eighty-four patients with IC participated in the study. After translation and back-translation, carried out by two independent translators, the concurrent validity of the WELCH was analyzed by correlating the questionnaire scores with the walking capacity assessed with the Gardner treadmill test. To determine the reliability of the WELCH, internal consistency and test-retest reliability with a seven-day interval between the two questionnaire applications were calculated. Results There were significant correlations between the WELCH score and the claudication onset distance (r = 0.64, p = 0.01) and total walking distance (r = 0.61, p = 0.01). The internal consistency was 0.84 and the intraclass correlation coefficient between questionnaire evaluations was 0.84. There were no differences in WELCH scores between the two questionnaire applications. Conclusion The Brazilian Portuguese version of the WELCH presents adequate validity and reliability indicators, which support its application to Brazilian patients with IC. PMID:26647720

  17. Walking along curved paths of different angles: the relationship between head and trunk turning.

    PubMed

    Sreenivasa, Manish N; Frissen, Ilja; Souman, Jan L; Ernst, Marc O

    2008-11-01

    Walking along a curved path requires coordinated motor actions of the entire body. Here, we investigate the relationship between head and trunk movements during walking. Previous studies have found that the head systematically turns into turns before the trunk does. This has been found to occur at a constant distance rather than at a constant time before a turn. We tested whether this anticipatory head behavior is spatially invariant for turns of different angles. Head and trunk positions and orientations were measured while participants walked around obstacles in 45 degrees, 90 degrees, 135 degrees or 180 degrees turns. The radius of the turns was either imposed or left free. We found that the head started to turn into the direction of the turn at a constant distance before the obstacle (approximately 1.1 m) for turn angles up to 135 degrees . During turns, the head was consistently oriented more into the direction of the turn than the trunk. This difference increased for larger turning angles and reached its maximum later in the turn for larger turns. Walking speeds decreased monotonically for increasing turn angles. Imposing fixed turn radii only affected the point at which the trunk started to turn into a turn. Our results support the view that anticipatory head movements during turns occur in order to gather advance visual information about the trajectory and potential obstacles.

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

    PubMed Central

    Rabkin, Janice; Sharify, Denise; Song, Lin

    2009-01-01

    Objectives. We implemented and evaluated multiple interventions to increase walking activity at a multicultural public housing site. Methods. A community-based participatory research partnership and community action teams assessed assets and barriers related to walking and developed multiple interventions to promote walking activity. Interventions included sponsoring walking groups, improving walking routes, providing information about walking options, and advocating for pedestrian safety. A pre–post study design was used to assess the changes in walking activity. Results. Self-reported walking activity increased among walking group participants from 65 to 109 minutes per day (P = .001). The proportion that reported being at least moderately active for at least 150 minutes per week increased from 62% to 81% (P = .018). Conclusions. A multicomponent intervention developed through participatory research methods that emphasized walking groups and included additional strategies to change the built and social environments increased walking activity at a public housing site in Seattle. PMID:19890163

  19. Selection pressures give composite correlated random walks Lévy walk characteristics.

    PubMed

    Reynolds, A M

    2013-09-01

    Composite correlated random walks have been posited as a strong alternative to Lévy walks as models of multi-scale forager movement patterns. Here it is shown that if plastic then intrinsic composite correlated random walks will, under selection pressures, evolve to resemble optimal Lévy walks when foraging is non-destructive. The fittest composite correlated random walkers are found to be those that come closest to being optimal Lévy walkers. This may explain why such a diverse range of foragers have movement patterns that can be approximated by optimal Lévy walks and shows that the 'Lévy-flight foraging' hypothesis has a broad hinterland. The new findings are consistent with recent observations of mussels Mytilus edulis and the Australian desert ant Melophorus bagoti which suggest that animals approximate a Lévy walk by adopting an intrinsic composite movement strategy with different modes.

  20. How do environmental factors influence walking in groups? A walk-along study.

    PubMed

    Kassavou, Aikaterini; French, David P; Chamberlain, Kerry

    2015-10-01

    Insufficient attention has been given to the influence of context on health-related behaviour change. This article reports on walk-along interviews conducted with 10 leaders of walking groups while leading their groups to investigate the influence of contextual factors on walking behaviours in groups. Data analysis used ideas from thematic analysis and grounded theory, approaching the data inductively. We identified that characteristics of place influenced the type of walking that people do in groups and the processes used by walkers to make sense of their behaviours in the places they walk. This research provides insight into how place influences walking in groups. It also suggests recommendations for co-ordinators and policymakers that could be used to facilitate behaviour change, when designing interventions targeting public health within the community. PMID:24296734

  1. Adaptive Walking in Alzheimer's Disease

    PubMed Central

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

    2012-01-01

    The aim of this study is to analyze dual-task effects on free and adaptive gait in Alzheimer's disease (AD) patients. Nineteen elders with AD participated in the study. A veteran neuropsychiatrist established the degree of AD in the sample. To determine dual-task effects on free and adaptive gait, patients performed five trials for each experimental condition: free and adaptive gait with and without a dual-task (regressive countdown). Spatial and temporal parameters were collected through an optoelectronic tridimensional system. The central stride was analyzed in free gait, and the steps immediately before (approaching phase) and during the obstacle crossing were analyzed in adaptive gait. Results indicated that AD patients walked more slowly during adaptive gait and free gait, using conservative strategies when confronted either with an obstacle or a secondary task. Furthermore, patients sought for stability to perform the tasks, particularly for adaptive gait with dual task, who used anticipatory and online adjustments to perform the task. Therefore, the increase of task complexity enhances cognitive load and risk of falls for AD patients. PMID:22991684

  2. Adaptive walking in Alzheimer's disease.

    PubMed

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

    2012-01-01

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

  3. Time to prioritise safe walking.

    PubMed

    Toroyan, Tami; Khayesi, Meleckidzedeck; Peden, Margie

    2013-01-01

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

  4. Design of a walking robot

    NASA Technical Reports Server (NTRS)

    Whittaker, William; Dowling, Kevin

    1994-01-01

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

  5. Design of a walking robot

    NASA Astrophysics Data System (ADS)

    Whittaker, William; Dowling, Kevin

    1994-03-01

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

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

    NASA Technical Reports Server (NTRS)

    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 (P<0.01) between the high impact and low/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 (P<0.01) during the high impact phase while that about the flexion-extension axis was significantly decreased (P<0.01) 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 fixation of targets during walking.

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

    PubMed

    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.

  8. Measuring Oscillating Walking Paths with a LIDAR

    PubMed Central

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

    2011-01-01

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

  9. Walking and serum cholesterol in adults.

    PubMed Central

    Tucker, L A; Friedman, G M

    1990-01-01

    We measured the association between walking for exercise and the ratio of total cholesterol/HDL cholesterol in 3,621 adults. After controlling for age, gender, income, body fat, alcohol use, exercise other than walking, and cigarette smoking, adults in the high, moderate, and low duration walking categories were compared to those in the no walking-no exercise category. The relative risk for total/HDL ratios of 5.0 or more were .46 (95% CI = .27, .80), .48 (95% total/HDL ratios of 5.0 or more were .46 (95% CI = .27, .80), .48 (95% CI = .30, .76), and 1.11 (95% CI = .81, 1.53) respectively. PMID:2382750

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

    MedlinePlus

    ... tizanidine are generally effective in treating this symptom. Balance : Balance problems typically result in a swaying and “drunken” ... factors for falls are complex and include: poor balance and slowed walking reduced proprioception (the sensation of ...

  11. Quantum walks with nonorthogonal position states.

    PubMed

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

    2012-12-14

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

  12. Energy Expenditure During Walking with Hand Weights.

    ERIC Educational Resources Information Center

    Makalous, Susan L.; And Others

    1988-01-01

    A study of 11 obese adults who exercised with hand weights concludes that using the weights increases the energy demands of walking but only slightly. Research and results are presented and analyzed. (JL)

  13. Parent Safety Perceptions of Child Walking Routes

    PubMed Central

    Boles, Shawn; Johnson-Shelton, Deb; Schlossberg, Marc; Richey, David

    2014-01-01

    Walking rates to school remain low for U.S. children in large part due to parent concern for child safety. Little research has investigated the specific features of streets and intersection networks that parents associate with safe walking networks for children. To investigate which aspects of the child walking environment lead to parental concern, parent volunteers conducted an audit of streets leading to seven elementary schools in a suburban school district. Parents were most likely to feel concern about streets that lacked sidewalks or had sidewalks with obstructions. Wheelchair-accessible routes were seen as appropriate for walking children. Parents expressed concern over safety at intersections, particularly those involving large streets; traffic controls did not mollify their concern. PMID:25664239

  14. Database of Standardized Questionnaires About Walking & Bicycling

    Cancer.gov

    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.

  15. 'Walking Meetings' May Boost Employee Health, Productivity

    MedlinePlus

    ... New research suggests you walk while you talk business. The small study found that converting a single ... management with the Donald R. Tapia School of Business at Saint Leo University in Florida. Clayton, who ...

  16. Walking with coffee: why does it spill?

    PubMed

    Mayer, H C; Krechetnikov, R

    2012-04-01

    In our busy lives, almost all of us have to walk with a cup of coffee. While often we spill the drink, this familiar phenomenon has never been explored systematically. Here we report on the results of an experimental study of the conditions under which coffee spills for various walking speeds and initial liquid levels in the cup. These observations are analyzed from the dynamical systems and fluid mechanics viewpoints as well as with the help of a model developed here. Particularities of the common cup sizes, the coffee properties, and the biomechanics of walking proved to be responsible for the spilling phenomenon. The studied problem represents an example of the interplay between the complex motion of a cup, due to the biomechanics of a walking individual, and the low-viscosity-liquid dynamics in it. PMID:22680548

  17. Quantum random walks with decoherent coins

    SciTech Connect

    Brun, Todd A.; Ambainis, Andris; Carteret, H.A.

    2003-03-01

    The quantum random walk has been much studied recently, largely due to its highly nonclassical behavior. In this paper, we study one possible route to classical behavior for the discrete quantum walk on the line: the presence of decoherence in the quantum ''coin'' which drives the walk. We find exact analytical expressions for the time dependence of the first two moments of position, and show that in the long-time limit the variance grows linearly with time, unlike the unitary walk. We compare this to the results of direct numerical simulation, and see how the form of the position distribution changes from the unitary to the usual classical result as we increase the strength of the decoherence.

  18. Real time visualization of quantum walk

    SciTech Connect

    Miyazaki, Akihide; Hamada, Shinji; Sekino, Hideo

    2014-02-20

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

  19. Measuring oscillating walking paths with a LIDAR.

    PubMed

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

    2011-01-01

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

  20. Second harmonic generation of off axial vortex beam in the case of walk-off effect

    NASA Astrophysics Data System (ADS)

    Chen, Shunyi; Ding, Panfeng; Pu, Jixiong

    2016-07-01

    Process of off axial vortex beam propagating in negative uniaxial crystal is investigated in this work. Firstly, we get the formulae of the normalized electric field and calculate the location of vortices for second harmonic beam in two type of phase matching. Then, numerical analysis verifies that the intensity distribution and location of vortices of the first order original vortex beam depend on the walk-off angle and off axial magnitude. It is shown that, in type I phase matching, the distribution of vortices is symmetrical about the horizontal axis, the separation distance increases as the off axial magnitude increases or the off axial magnitude deceases. However, in type II phase matching, the vortices are symmetrical along with some vertical axis, and increase of the walk-off angle or off axial magnitude leads to larger separation distance. Finally, the case of high order original off axial vortex beam is also investigated.

  1. Nordic Walking Practice Might Improve Plantar Pressure Distribution

    ERIC Educational Resources Information Center

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

    2011-01-01

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

  2. Walking after Stroke: Comfortable versus Maximum Safe Speed.

    ERIC Educational Resources Information Center

    Bohannon, Richard W.

    1992-01-01

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

  3. Urban Walking and the Pedagogies of the Street

    ERIC Educational Resources Information Center

    Bairner, Alan

    2011-01-01

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

  4. Walking and Eating Behavior of Toddlers at 12 Months Old

    ERIC Educational Resources Information Center

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

    2004-01-01

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

  5. Walking as a social practice: dispersed walking and the organisation of everyday practices.

    PubMed

    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. PMID:26853086

  6. Quantum Walks: Theory, Application, and Implementation

    NASA Astrophysics Data System (ADS)

    Schmitz, Albert Thomas

    The quantum walk is a method for conceptualizing and designing quantum computing algorithms and it comes in two forms: the continuous-time and discrete-time quantum walk. The thesis is organized into three parts, each of which looks to develop the concept and uses of the quantum walk. The first part is the theory of the quantum walk. This includes definitions and considerations for the various incarnations of the discrete-time quantum walk and a discussion on the general method for connecting the continuous-time and discrete-time versions. As a result, it is shown that most versions of the discrete-time quantum walk can be put into a general form and this can be used to simulate any continuous-time quantum walk. The second part uses these results for a hypothetical application. The application presented is a search algorithm that appears to scale in the time for completion independent of the size of the search space. This behavior is then elaborated upon and shown to have general qualitative agreement with simulations to within the approximations that are made. The third part introduces a method of implementation. Given a universal quantum computer, the method is discussed and shown to simulate an arbitrary discrete-time quantum walk. Some of the benefits of this method are that half the unitary evolution can be achieved without the use of any gates and there may be some possibility for error detection. The three parts combined suggest a possible experiment, given a quantum computing scheme of sufficient robustness.

  7. Balancing of the anthropomorphous robot walking

    NASA Astrophysics Data System (ADS)

    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.

  8. Quantum random walks using quantum accelerator modes

    SciTech Connect

    Ma, Z.-Y.; Burnett, K.; D'Arcy, M. B.; Gardiner, S. A.

    2006-01-15

    We discuss the use of high-order quantum accelerator modes to achieve an atom optical realization of a biased quantum random walk. We first discuss how one can create coexistent quantum accelerator modes, and hence how momentum transfer that depends on the atoms' internal state can be achieved. When combined with microwave driving of the transition between the states, a different type of atomic beam splitter results. This permits the realization of a biased quantum random walk through quantum accelerator modes.

  9. Estimating Distances from Parallaxes

    NASA Astrophysics Data System (ADS)

    Bailer-Jones, Coryn A. L.

    2015-10-01

    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 catalog. 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, e.g., the survey and the Galaxy. I demonstrate that a simple prior which decreases asymptotically to zero at infinite distance has good performance, accommodates nonpositive parallaxes, and does not require a bias correction.

  10. Uphill and Downhill Walking in Multiple Sclerosis

    PubMed Central

    Samaei, Afshin; Hajihasani, Abdolhamid; Fatemi, Elham; Motaharinezhad, Fatemeh

    2016-01-01

    Background: Various exercise protocols have been recommended for patients with multiple sclerosis (MS). We investigated the effects of uphill and downhill walking exercise on mobility, functional activities, and muscle strength in MS patients. Methods: Thirty-four MS patients were randomly allocated to either the downhill or uphill treadmill walking group for 12 sessions (3 times/wk) of 30 minutes' walking on a 10% negative slope (n = 17) or a 10% positive slope (n = 17), respectively. Measurements were taken before and after the intervention and after 4-week follow-up and included fatigue by Modified Fatigue Impact Scale; mobility by Modified Rivermead Mobility Index; disability by Guy's Neurological Disability Scale; functional activities by 2-Minute Walk Test, Timed 25-Foot Walk test, and Timed Up and Go test; balance indices by Biodex Balance System; and quadriceps and hamstring isometric muscles by torque of left and right knee joints. Analysis of variance with repeated measures was used to investigate the intervention effects on the measurements. Results: After the intervention, significant improvement was found in the downhill group versus the uphill group in terms of fatigue, mobility, and disability indices; functional activities; balance indices; and quadriceps isometric torque (P < .05). The results were stable at 4-week follow-up. Conclusions: Downhill walking on a treadmill may improve muscle performance, functional activity, and balance control in MS patients. These findings support the idea of using eccentric exercise training in MS rehabilitation protocols. PMID:26917996

  11. Winding angles of long lattice walks

    NASA Astrophysics Data System (ADS)

    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 <θ2> of random walks converges to the theoretical form when N → ∞. For self-avoiding walks on the square lattice, we show that the ratio <θ4>/<θ2>2 converges slowly to the Gaussian value 3. For self-avoiding walks on the cubic lattice, we find that the ratio <θ4>/<θ2>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.

  12. Calcaneal loading during walking and running

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

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

  13. Convergence of quantum random walks with decoherence

    SciTech Connect

    Fan Shimao; Feng Zhiyong; Yang, Wei-Shih; Xiong Sheng

    2011-10-15

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

  14. Winding angles of long lattice walks.

    PubMed

    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 10(7). We show that the mean square winding angle 〈θ(2)〉 of random walks converges to the theoretical form when N → ∞. For self-avoiding walks on the square lattice, we show that the ratio 〈θ(4)〉/〈θ(2)〉(2) converges slowly to the Gaussian value 3. For self-avoiding walks on the cubic lattice, we find that the ratio 〈θ(4)〉/〈θ(2)〉(2) exhibits non-monotonic dependence on N and reaches a maximum of 3.73(1) for N ≈ 10(4). 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 2(i) steps. We find that the square winding angle of the ith segment increases approximately as i(0.5), which leads to an increase of the total square winding angle proportional to (lnN)(1.5). PMID:27394124

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

    PubMed Central

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

    2012-01-01

    This randomized trial proposed to determine if there were differences in calf muscle StO2 parameters in patients before and after 12 weeks of a traditional walking or walking-with-poles exercise program. Data were collected on 85 patients who were randomized to a traditional walking program (n = 40) or walking-with-poles program (n = 45) of exercise training. Patients walked for 3 times weekly for 12 weeks. Seventy-one patients completed both the baseline and the 12-week follow-up progressive treadmill tests (n = 36 traditional walking and n = 35 walking-with-poles). Using the near-infrared spectroscopy measures, StO2 was measured prior to, during, and after exercise. At baseline, calf muscle oxygenation decreased from 56 ± 17% prior to the treadmill test to 16 ± 18% at peak exercise. The time elapsed prior to reaching nadir StO2 values increased more in the traditional walking group when compared to the walking-with-poles group. Likewise, absolute walking time increased more in the traditional walking group than in the walking-with-poles group. Tissue oxygenation decline during treadmill testing was less for patients assigned to a 12-week traditional walking program when compared to those assigned to a 12-week walking-with-poles program. In conclusion, the 12-week traditional walking program was superior to walking-with-poles in improving tissue deoxygenation in patients with PAD. PMID:23050152

  16. Experimental implementation of the quantum random-walk algorithm

    SciTech Connect

    Du Jiangfeng; Li Hui; Shi Mingjun; Zhou Xianyi; Han Rongdian; Xu Xiaodong; Wu Jihui

    2003-04-01

    The quantum random walk is a possible approach to construct quantum algorithms. Several groups have investigated the quantum random walk and experimental schemes were proposed. In this paper, we present the experimental implementation of the quantum random-walk algorithm on a nuclear-magnetic-resonance quantum computer. We observe that the quantum walk is in sharp contrast to its classical counterpart. In particular, the properties of the quantum walk strongly depends on the quantum entanglement.

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

    PubMed

    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. PMID:27463106

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

    PubMed

    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.

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

    PubMed Central

    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. PMID:27463106

  20. Distance learning perspectives.

    PubMed

    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.

  1. Distance learning perspectives.

    PubMed

    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. PMID:24222934

  2. Technology and Distance Education.

    ERIC Educational Resources Information Center

    Pelton, J. N.; Bates, A. W.

    1991-01-01

    Two articles evaluate the impact of new transmission and information technologies on education: "Technology and Education--Friend or Foe?" (Pelton) and "Third Generation Distance Education: The Challenge of New Technology" (Bates). (SK)

  3. Walk and die: an unusual presentation of head injury.

    PubMed

    Veevers, Abigail E; Lawler, William; Rutty, Guy N

    2009-11-01

    We report three deaths in young adult males following closed blunt trauma to the head and face where the affected individuals were able to walk away from the incident, before subsequently collapsing and dying a short distance from the site of the assault. In each case, due to the rapidity of the posttrauma collapse, the pathologist was faced with a diagnostic difficulty at autopsy; the external examination revealed multiple injuries to the head and face, but internal examinations showed limited findings with no structural explanation for the death. We discuss possible mechanisms that could account for this scenario, the implications of alcohol consumption with a concussive head injury, and parallels that can be drawn with the so-called "talk and die,"talk and deteriorate," and "second impact syndrome." Finally, the possible role of so-called "postexercise peril" is discussed in relation to these deaths. PMID:19840206

  4. A simplified analytical random walk model for proton dose calculation

    NASA Astrophysics Data System (ADS)

    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.

  5. Walking and running at resonance.

    PubMed

    Ahlborn, Boye K; Blake, Robert W

    2002-01-01

    Humans and other animals can temporarily store mechanical energy in elastic oscillations, f(el), of body parts and in pendulum oscillations, f(p) = const sq.rt (g/L), of legs, length L, or other appendages, and thereby reduce the energy consumption of locomotion. However, energy saving only occurs if these oscillations are tuned to the leg propagation frequency f. It has long been known that f is tuned to the pendulum frequency of the free-swinging leg of walkers. During running the leg frequency increases to some new value f = f(r). We propose that in order to maintain resonance the animal, mass M, actively increases its leg pendulum frequency to the new value f(p,r) =const sq.rt (a(y)/L)=f(r), by giving its hips a vertical acceleration a(y)= F(y)/M. The pendulum frequency is increased if the impact force F(y) of the stance foot is larger than Mg, explaining the observation by Alexander and Bennet-Clark (1976) that F(v) becomes larger than Mg when animals start to run. Our model predictions of the running velocity U(r) as function of L, F(v), are in agreement with measurements of these quantities (Farley et al. 1993). The leg's longitudinal elastic oscillation frequency scales as f(el) = const sq.rt (k/M). Experiments by Ferris et al., (1998) show that runners adjust their leg's stiffness, k, when running on surfaces of different elasticity so that the total stiffness k remains constant. Our analysis of their data suggests that the longitudinal oscillations of the stance leg are indeed kept in tune with the running frequency. Therefore we conclude that humans, and by extension all animals, maintain resonance during running. Our model also predicts the Froude number of walking-running transitions, Fr = U(2)/gL approximately 0.5 in good agreement with measurements.

  6. Angular momentum in human walking.

    PubMed

    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.

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

    USGS Publications Warehouse

    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.

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

    PubMed

    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.

  9. Understanding walking activity in multiple sclerosis: step count, walking intensity and uninterrupted walking activity duration related to degree of disability.

    PubMed

    Neven, An; Vanderstraeten, Annelien; Janssens, Davy; Wets, Geert; Feys, Peter

    2016-09-01

    In multiple sclerosis (MS), physical activity (PA) is most commonly measured as number of steps, while also walking intensity and walking activity duration are keys for a healthy lifestyle. The aim of this study was to investigate (1) the number of steps persons with MS (PwMS) take; (2) the number of steps they take at low and moderate intensity; and (3) their walking activity duration for 2, 3, 6, 10, 12 and 14 uninterrupted minutes; all related to the degree of disability. 64 PwMS participated, distinguished in a mild (n = 31) and moderate MS subgroup (n = 34) based on their ambulatory dysfunction (Disease Steps). Standardized clinical tests were performed, and step data from the StepWatch Activity Monitor were collected for seven consecutive days. The results showed that (1) step count in PwMS was lower than PA recommendations, and is negatively influenced by a higher disability degree. (2) No walking was registered during 77 % of the day. PwMS are making steps for 22 % at low and only 1 % at moderate intensity. (3) Both MS subgroups rarely walk for more than six uninterrupted minutes, especially not at moderate intensity. PwMS need to be encouraged to make steps at moderate intensity, and to make steps for longer periods of time (minimal ten uninterrupted minutes).

  10. Kinematic evaluation of virtual walking trajectories.

    PubMed

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

    2013-04-01

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

  11. Kinematic evaluation of virtual walking trajectories.

    PubMed

    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.

  12. 10 CFR 431.302 - Definitions concerning walk-in coolers and walk-in freezers.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 3 2010-01-01 2010-01-01 false Definitions concerning walk-in coolers and walk-in freezers. 431.302 Section 431.302 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION ENERGY EFFICIENCY PROGRAM... enclosed storage space refrigerated to temperatures, respectively, above, and at or below 32...

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

    SciTech Connect

    Dimcovic, Zlatko; Rockwell, Daniel; Milligan, Ian; Burton, Robert M.; Kovchegov, Yevgeniy; Nguyen, Thinh

    2011-09-15

    We formulate a framework for discrete-time quantum walks, motivated by classical random walks with memory. We present a specific representation of the classical walk with memory 2, on which this is based. The framework has no need for coin spaces, it imposes no constraints on the evolution operator other than unitarity, and is unifying of other approaches. As an example we construct a symmetric discrete-time quantum walk on the semi-infinite binary tree. The generating function of the amplitude at the root is computed in closed form, as a function of time and the initial level n in the tree, and we find the asymptotic and a full numerical solution for the amplitude. It exhibits a sharp interference peak and a power-law tail, as opposed to the exponentially decaying tail of a broadly peaked distribution of the classical symmetric random walk on a binary tree. The probability peak is orders of magnitude larger than it is for the classical walk (already at small n). The quantum walk shows a polynomial algorithmic speedup in n over the classical walk, which we conjecture to be of the order 2/3, based on strong trends in data.

  14. Presence at a distance.

    PubMed

    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. PMID:26799909

  15. Biomarkers for the evaluation of immunological properties during the shikoku walking pilgrimage.

    PubMed

    Yoshino, K; Umeno, A; Shichiri, M; Watanabe, H; Ishida, N; Kojima, M; Iwaki, S; Hagihara, Y; Nakamura, M; Yoshida, Y

    2015-01-01

    It is important to determine the immunological properties for the maintenance of health. We chose the Shikoku Walking Pilgrimage to assess the proper biomarkers for the evaluation of immunological properties. We examined whether the Shikoku Walking Pilgrimage could have a positive effect on the mental and physical health of walking participants by using several biomarkers proposed by our laboratory. Twelve non-randomized healthy male volunteers including 3 twice attendees walked the Shikoku Walking Pilgrimage distance of 58.9 km over 3 days. Plasma, serum, urine, and saliva were collected from the volunteers during the pilgrimage and at 1 week before and after it. Immunological biomarkers, including lipid metabolism, oxidative stress, immune function, and catecholamines, were measured. Additionally, mood state scores, alertness, autonomic nervous system activity, and body motion levels during sleep were assessed. A significant decrease was observed in the subjective tension-anxiety levels and in the concentrations of serum low-density lipoprotein cholesterol, plasma hydroxyoctadecadienoic acid (HODE), and urine adrenaline during the pilgrimage as compared to the values of these parameters before the participants embarked on the pilgrimage. The serum levels of brain-derived neurotrophic factor (BDNF) were significantly increased 1 week after the pilgrimage relative to those assessed previously. No significant differences in subjective fatigue and the flicker perception threshold were observed. These results suggest that the Shikoku Walking Pilgrimage can exert a positive effect on mental and physical health as particularly shown in the reduction of tensionanxiety and oxidative stress without the accompaniment of fatigue. HODE correlated significantly with typical immunological marker natural killer cell activity and immunoglobulin G. This suggests that there are promising biomarkers such as HODE, NK activity, BDNF, LDL-c, and IgG for assessing the immunological

  16. Physical activity, functional capacity, and step variability during walking in people with lower-limb amputation.

    PubMed

    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. PMID:24731451

  17. The role of gravity in human walking: pendular energy exchange, external work and optimal speed.

    PubMed

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

    2000-11-01

    During walking on Earth, at 1.0 g of gravity, the work done by the muscles to maintain the motion of the centre of mass of the body (W(ext)) is reduced by a pendulum-like exchange between gravitational potential energy and kinetic energy. The weight-specific W(ext) per unit distance attains a minimum of 0.3 J x kg(-1) x m(-1) at about 4.5 km x h(-1) in adults. The effect of a gravity change has been studied during walking on a force platform fixed to the floor of an aircraft undergoing flight profiles which resulted in a simulated gravity of 0.4 and 1.5 times that on Earth. At 0.4 g, such as on Mars, the minimum W(ext) was 0.15 J x kg(-1) x m(-1), half that on Earth and occurred at a slower speed, about 2.5 km x h(-1). The range of walking speeds is about half that on Earth. At 1.5 g, the lowest value of W(ext) was 0.60 J x kg(-1) x m(-1), twice that on Earth; it was nearly constant up to about 4.3 km x h(-1) and then increased with speed. The range of walking speeds is probably greater than that on Earth. A model is presented in which the speed for an optimum exchange between potential and kinetic energy, the 'optimal speed', is predicted by the balance between the forward deceleration due to the lift of the body against gravity and the forward deceleration due to the impact against the ground. In conclusion, over the range studied, gravity increases the work required to walk, but it also increases the range of walking speeds.

  18. Physical activity, functional capacity, and step variability during walking in people with lower-limb amputation.

    PubMed

    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.

  19. Long distance entanglement distribution

    NASA Astrophysics Data System (ADS)

    Broadfoot, Stuart Graham

    Developments in the interdisciplinary field of quantum information open up previously impossible abilities in the realms of information processing and communication. Quantum entanglement has emerged as one property of quantum systems that acts as a resource for quantum information processing and, in particular, enables teleportation and secure cryptography. Therefore, the creation of entangled resources is of key importance for the application of these technologies. Despite a great deal of research the efficient creation of entanglement over long distances is limited by inevitable noise. This problem can be overcome by creating entanglement between nodes in a network and then performing operations to distribute the entanglement over a long distance. This thesis contributes to the field of entanglement distribution within such quantum networks. Entanglement distribution has been extensively studied for one-dimensional networks resulting in "quantum repeater" protocols. However, little work has been done on higher dimensional networks. In these networks a fundamentally different scaling, called "long distance entanglement distribution", can appear between the resources and the distance separating the systems to be entangled. I reveal protocols that enable long distance entanglement distribution for quantum networks composed of mixed state and give a few limitations to the capabilities of entanglement distribution. To aid in the implementation of all entanglement distribution protocols I finish by introducing a new system, composed of an optical nanofibre coupled to a carbon nanotube, that may enable new forms of photo-detectors and quantum memories.

  20. Learning to walk changes infants' social interactions.

    PubMed

    Clearfield, Melissa W

    2011-02-01

    The onset of crawling marks a motor, cognitive and social milestone. The present study investigated whether independent walking marks a second milestone for social behaviors. In Experiment 1, the social and exploratory behaviors of crawling infants were observed while crawling and in a baby-walker, resulting in no differences based on posture. In Experiment 2, the social behaviors of independently walking infants were compared to age-matched crawling infants in a baby-walker. Independently walking infants spent significantly more time interacting with the toys and with their mothers, and also made more vocalizations and more directed gestures compared to infants in the walker. Experiment 3 tracked infants' social behaviors longitudinally across the transition from crawling and walking. Even when controlled for age, the transition to independent walking marked increased interaction time with mothers, as well as more sophisticated interactions, including directing mothers' attention to particular objects. The results suggest a developmental progression linking social interactions with milestones in locomotor development. PMID:20478619

  1. Stereoscopic distance perception

    NASA Technical Reports Server (NTRS)

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  3. Distance estimation in the third dimension in desert ants.

    PubMed

    Wohlgemuth, S; Ronacher, B; Wehner, R

    2002-05-01

    Desert ants of the genus Cataglyphis perform large-scale foraging excursions from which they return to their nest by path integration. They do so by integrating courses steered and the distances travelled into a continually updated home vector. While it is known that the angular orientation is based on skylight cues, it still is largely enigmatic how the ants measure distances travelled. We extended the ants' task into the third dimension by training them to walk within an array of uphill and downhill channels, and later testing them on flat terrain, or vice versa. In these tests the ants indicated homing distances that did not correspond to the distances actually travelled, but to the ground distances; that is, to the sum of the horizontal projections of the uphill and downhill segments of the ants' paths. These results suggest a much more sophisticated mechanism of distance estimation than hitherto thought. The ants must be able to measure the slopes of undulating terrain and to integrate this information into their "odometer" for the distance estimation process.

  4. Emerging distance degree programs.

    PubMed

    Birnbaum, D; Greenhalgh, T

    2000-01-01

    The variation in program focus and style is examined in this column, which also identifies resources for evaluation. The integration of Web-based or other distance modality materials to conventional courses, and the expansion of traditional universities to include a virtual campus, should proceed with caution and systematic evaluation. It is an evolution that offers both rewards and pitfalls, but requires more rigorous examination. This article provides information about pedagogical issues and additional distance-education master's degree programs. Some are new, while others are established.

  5. Poorer clock draw test scores are associated with greater functional impairment in peripheral artery disease: The Walking and Leg Circulation Study II

    PubMed Central

    Zimmermann, Laura J; Ferrucci, Luigi; Liu, Kiang; Tian, Lu; Guralnik, Jack M; Criqui, Michael H; Liao, Yihua; McDermott, Mary M

    2016-01-01

    We hypothesized that, in the absence of clinically recognized dementia, cognitive dysfunction measured by the clock draw test (CDT) is associated with greater functional impairment in men and women with peripheral artery disease (PAD). Participants were men and women aged 60 years and older with Mini-Mental Status Examination scores ≥ 24 with PAD (n = 335) and without PAD (n = 234). We evaluated the 6-minute walk test, 4-meter walking velocity at usual and fastest pace, the Short Physical Performance Battery (SPPB), and accelerometer-measured physical activity. CDTs were scored using the Shulman system as follows: Category 1 (worst): CDT score 0–2; Category 2: CDT score 3; Category 3 (best): CDT score 4–5. Results were adjusted for age, sex, race, education, ankle–brachial index (ABI), and comorbidities. In individuals with PAD, lower CDT scores were associated with slower 4-meter usual-paced walking velocity (Category 1: 0.78 meters/second; Category 2: 0.83 meters/second; Category 3: 0.86 meters/second; p-trend = 0.025) and lower physical activity (Category 1: 420 activity units; Category 2: 677 activity units; Category 3: 701 activity units; p-trend = 0.045). Poorer CDT scores were also associated with worse functional performance in individuals without PAD (usual and fast-paced walking velocity and SPPB, p-trend = 0.022, 0.043, and 0.031, respectively). In conclusion, cognitive impairment identified with CDT is independently associated with greater functional impairment in older, dementia-free individuals with and without PAD. Longitudinal studies are necessary to explore whether baseline CDT scores and changes in CDT scores over time can predict long-term decline in functional performance in individuals with and without PAD. PMID:21636676

  6. Protocol Variations and Six-Minute Walk Test Performance in Stroke Survivors: A Systematic Review with Meta-Analysis

    PubMed Central

    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

  7. Quantum Walks on Two Kinds of Two-Dimensional Models

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

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

  8. Mean first return time for random walks on weighted networks

    NASA Astrophysics Data System (ADS)

    Jing, Xing-Li; Ling, Xiang; Long, Jiancheng; Shi, Qing; Hu, Mao-Bin

    2015-11-01

    Random walks on complex networks are of great importance to understand various types of phenomena in real world. In this paper, two types of biased random walks on nonassortative weighted networks are studied: edge-weight-based random walks and node-strength-based random walks, both of which are extended from the normal random walk model. Exact expressions for stationary distribution and mean first return time (MFRT) are derived and examined by simulation. The results will be helpful for understanding the influences of weights on the behavior of random walks.

  9. Universal quantum computation by discontinuous quantum walk

    SciTech Connect

    Underwood, Michael S.; Feder, David L.

    2010-10-15

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

  10. [Use of walk tests in pulmonology].

    PubMed

    2012-01-01

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

  11. Photonics walking up a human hair

    NASA Astrophysics Data System (ADS)

    Zeng, Hao; Parmeggiani, Camilla; Martella, Daniele; Wasylczyk, Piotr; Burresi, Matteo; Wiersma, Diederik S.

    2016-03-01

    While animals have access to sugars as energy source, this option is generally not available to artificial machines and robots. Energy delivery is thus the bottleneck for creating independent robots and machines, especially on micro- and nano- meter length scales. We have found a way to produce polymeric nano-structures with local control over the molecular alignment, which allowed us to solve the above issue. By using a combination of polymers, of which part is optically sensitive, we can create complex functional structures with nanometer accuracy, responsive to light. In particular, this allowed us to realize a structure that can move autonomously over surfaces (it can "walk") using the environmental light as its energy source. The robot is only 60 μm in total length, thereby smaller than any known terrestrial walking species, and it is capable of random, directional walking and rotating on different dry surfaces.

  12. Design and use of improved walking aids.

    PubMed

    Nava, L C; Laura, P A

    1985-10-01

    The design of crutches and walking sticks to assist the disabled has not varied much since their original conception, some 5000 years ago. From an engineering viewpoint one must consider crutches and walking sticks as dynamic mechanical systems which alleviate a disability; they may act as supports, help the user to recover from stumbling, or transmit from the arms, the energy required to lift the feet from the ground, an action not provided by artificial ankle joints. We describe some dynamic walking aids recently developed at the Instituto de Mecánica Aplicada, and discuss their design and our experience with their use. They are adjustable in height, shock absorbing and have non-slipping tips. Specially developed aids have been designed for children; they are versatile and their use has been made psychologically attractive.

  13. Mesoscopic description of random walks on combs.

    PubMed

    Méndez, Vicenç; Iomin, Alexander; Campos, Daniel; Horsthemke, Werner

    2015-12-01

    Combs are a simple caricature of various types of natural branched structures, which belong to the category of loopless graphs and consist of a backbone and branches. We study continuous time random walks on combs and present a generic method to obtain their transport properties. The random walk along the branches may be biased, and we account for the effect of the branches by renormalizing the waiting time probability distribution function for the motion along the backbone. We analyze the overall diffusion properties along the backbone and find normal diffusion, anomalous diffusion, and stochastic localization (diffusion failure), respectively, depending on the characteristics of the continuous time random walk along the branches, and compare our analytical results with stochastic simulations. PMID:26764637

  14. From attitude to action: What shapes attitude toward walking to/from school and how does it influence actual behaviors?

    PubMed

    Yu, Chia-Yuan; Zhu, Xuemei

    2016-09-01

    Walking to/from school could promote children's physical activity and help combat childhood obesity. Parental attitudes have been identified as one of the important predictors. But it is unclear what factors shape parental attitudes, and how those in turn influence children's school travel. This study addresses this gap of knowledge by examining the mediating effect of parental attitudes for the relationships between personal, social, and built environmental factors and children's walking-to/from-school behaviors. Survey data (N=2597) were collected from 20 public elementary schools in Austin, Texas, measuring students' typical school travel mode; personal, social, and built environmental factors related to walking-to/from-school; and relevant parental attitudes. The analysis was conducted in M-plus 6.11 to test the proposed conceptual framework using a structural equation model (SEM). Parental attitudes showed significant mediating effects on walking-to/from-school behaviors. Older child, positive peer influence, walkable home-to-school distance, and favorable walking environments were associated with more enjoyment and lower attitudinal barriers, and in turn increased likelihood of walking to/from school. Being Hispanic, increased car ownership, and stronger traffic safety concerns reduced enjoyment and increased attitudinal barriers, and thus decreased likelihood of walking to/from school. This study highlighted the importance of using multilevel interventions to reduce attitudinal barriers and increase enjoyment of walking to/from school. Collaborations among different stakeholders are needed to address environmental issues (e.g., safety concerns) and social factors (e.g., peer influence), while being sensitive to personal factors (e.g., age, ethnicity, and car ownership). PMID:27374942

  15. A systematic review of the effects of pharmacological agents on walking function in people with spinal cord injury.

    PubMed

    Domingo, Antoinette; Al-Yahya, Abdulaziz A; Asiri, Yousif; Eng, Janice J; Lam, Tania

    2012-03-20

    Studies of spinalized animals indicate that some pharmacological agents may act on receptors in the spinal cord, helping to produce coordinated locomotor movement. Other drugs may help to ameliorate the neuropathological changes resulting from spinal cord injury (SCI), such as spasticity or demyelination, to improve walking. The purpose of this study was to systematically review the effects of pharmacological agents on gait in people with SCI. A keyword literature search of articles that evaluated the effects of drugs on walking after SCI was performed using the databases MEDLINE/PubMed, CINAHL, EMBASE, PsycINFO, and hand searching. Two reviewers independently evaluated each study, using the Physiotherapy Evidence Database (PEDro) tool for randomized clinical trials (RCTs), and the modified Downs & Black scale for all other studies. Results were tabulated and levels of evidence were assigned. Eleven studies met the inclusion criteria. One RCT provided Level 1 evidence that GM-1 ganglioside in combination with physical therapy improved motor scores, walking velocity, and distance better than placebo and physical therapy in persons with incomplete SCI. Multiple studies (levels of evidence 1-5) showed that clonidine and cyproheptadine may improve locomotor function and walking speed in severely impaired individuals with incomplete SCI. Gains in walking speed associated with GM-1, cyproheptadine, and clonidine are low compared to those seen with locomotor training. There was also Level 1 evidence that 4-aminopyridine and L-dopa were no better than placebo in helping to improve gait. Two Level 5 studies showed that baclofen had little to no effect on improving walking in persons with incomplete SCI. There is limited evidence that pharmacological agents tested so far would facilitate the recovery of walking after SCI. More studies are needed to better understand the effects of drugs combined with gait training on walking outcomes in people with SCI.

  16. Idiopathic toe walking and sensory processing dysfunction

    PubMed Central

    2010-01-01

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

  17. Quantum Random Walks with General Particle States

    NASA Astrophysics Data System (ADS)

    Belton, Alexander C. R.

    2014-06-01

    A convergence theorem is obtained for quantum random walks with particles in an arbitrary normal state. This unifies and extends previous work on repeated-interactions models, including that of Attal and Pautrat (Ann Henri Poincaré 7:59-104 2006) and Belton (J Lond Math Soc 81:412-434, 2010; Commun Math Phys 300:317-329, 2010). When the random-walk generator acts by ampliation and either multiplication or conjugation by a unitary operator, it is shown that the quantum stochastic cocycle which arises in the limit is driven by a unitary process.

  18. Random Walk Weakly Attracted to a Wall

    NASA Astrophysics Data System (ADS)

    de Coninck, Joël; Dunlop, François; Huillet, Thierry

    2008-10-01

    We consider a random walk X n in ℤ+, starting at X 0= x≥0, with transition probabilities {P}(X_{n+1}=Xn±1|Xn=yge1)={1over2}mp{δover4y+2δ} and X n+1=1 whenever X n =0. We prove {E}Xn˜const. n^{1-{δ over2}} as n ↗∞ when δ∈(1,2). The proof is based upon the Karlin-McGregor spectral representation, which is made explicit for this random walk.

  19. Copyright and Distance Education.

    ERIC Educational Resources Information Center

    MacKnight, Carol B.

    2000-01-01

    Reports on three workshops offering copyright education for library and computer services staff and administrators. Topics covered included: copyright (e.g., the Copyright Act of 1976 and classroom teaching); digital distance education issues (application of fair use to on-line teaching); and compliance (under the Digital Millennium Copyright…

  20. Prospect of Distance Learning

    ERIC Educational Resources Information Center

    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…

  1. Accreditation of Distance Learning

    ERIC Educational Resources Information Center

    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…

  2. Advances in Distance Learning.

    ERIC Educational Resources Information Center

    1999

    This document contains three symposium papers on advances in distance learning. "The Adoption of Computer Technology and Telecommunications: A Case Study" (Larry M. Dooley, Teri Metcalf, Ann Martinez) reports on a study of the possible applications of two theoretical models (Rogers' Diffusion of Innovations model and the Concerns-Based Adoption…

  3. Rapport in Distance Education

    ERIC Educational Resources Information Center

    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…

  4. Distance Learning Programming.

    ERIC Educational Resources Information Center

    Lucero, Jesus Ricardo; And Others

    This resource guide for distance learning information, courses, and programming covers: (1) audiographics programming by the Pennsylvania Teleteaching Project; (2) cable programming, including the Cable Alliance for Education's Cable in the Classroom projects, Consumer News and Business Channel, Nostalgia Television, PENNARAMA Channel, Silent…

  5. Distance Education Policy Framework.

    ERIC Educational Resources Information Center

    Oregon State System of Higher Education, Eugene.

    This description of the policy framework for Oregon's distance education program gives an overview of the progress to date, outlines five areas in which policy must be developed, and identifies a number of priorities among those areas. Progress is reported in the following areas: several initiatives that incorporate new telecommunications and…

  6. Going the Distance

    ERIC Educational Resources Information Center

    Barack, Lauren

    2005-01-01

    Sixty years ago, distance education probably involved a pen, paper, and secretarial classes conducted via snail mail. Today, students in ever-increasing numbers are more likely to link to the Internet to learn how to conjugate French verbs or dissect frogs in Advanced Placement courses, according to a new landmark study from the U. S. Department…

  7. Time-distance helioseismology

    NASA Technical Reports Server (NTRS)

    Duvall, T. L., Jr.; Jefferies, S. M.; Harvey, J. W.; Pomerantz, M. A.

    1993-01-01

    It is shown here that it is possible to extract time-distance information from temporal cross-correlations of the intensity fluctuation on the solar surface. This approach opens the way for seismic studies of local solar phenomena such subsurface inhomogeneities near sunspots and should help to refine global models of the internal velocity stratification in the sun.

  8. Misconceptions of Astronomical Distances

    ERIC Educational Resources Information Center

    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…

  9. Technology & Distance Learning Survey.

    ERIC Educational Resources Information Center

    Florida Human Resources Development, Inc., Gainesville.

    A survey was conducted to assess the current state of technology and distance learning awareness and usage in Florida's adult education and community-based programs. Data were gathered through a survey of 350 adult practitioners, literacy providers, community-based organizations and libraries throughout the state (125 responses [36 percent return…

  10. Encyclopedia of Distance Learning

    ERIC Educational Resources Information Center

    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…

  11. Faculty and Distance Education.

    ERIC Educational Resources Information Center

    Saba, Farhad, Ed.

    1998-01-01

    Outlines the role of faculty and issues that need to be addressed early on if large-scale distance education is going to be successful. Discusses academic freedom; intellectual property; training; compensation; and royalties and revenue sharing. Notes the importance of active involvement by faculty in shaping the university of the future. (AEF)

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

    PubMed Central

    2012-01-01

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

  13. A marching-walking hybrid induces step length adaptation and transfers to natural walking

    PubMed Central

    Long, Andrew W.; Finley, James M.

    2015-01-01

    Walking is highly adaptable to new demands and environments. We have previously studied adaptation of locomotor patterns via a split-belt treadmill, where subjects learn to walk with one foot moving faster than the other. Subjects learn to adapt their walking pattern by changing the location (spatial) and time (temporal) of foot placement. Here we asked whether we can induce adaptation of a specific walking pattern when one limb does not “walk” but instead marches in place (i.e., marching-walking hybrid). The marching leg's movement is limited during the stance phase, and thus certain sensory signals important for walking may be reduced. We hypothesized that this would produce a spatial-temporal strategy different from that of normal split-belt adaptation. Healthy subjects performed two experiments to determine whether they could adapt their spatial-temporal pattern of step lengths during the marching-walking hybrid and whether the learning transfers to over ground walking. Results showed that the hybrid group did adapt their step lengths, but the time course of adaptation and deadaption was slower than that for the split-belt group. We also observed that the hybrid group utilized a mostly spatial strategy whereas the split-belt group utilized both spatial and temporal strategies. Surprisingly, we found no significant difference between the hybrid and split-belt groups in over ground transfer. Moreover, the hybrid group retained more of the learned pattern when they returned to the treadmill. These findings suggest that physical rehabilitation with this marching-walking paradigm on conventional treadmills may produce changes in symmetry comparable to what is observed during split-belt training. PMID:25867742

  14. Impact of pedometer-based walking on menopausal women's sleep quality: a randomized controlled trial.

    PubMed

    Tadayon, M; Abedi, P; Farshadbakht, F

    2016-08-01

    Objective Sleep disturbances are one of the most common psycho-physiological issues among postmenopausal women. This study was designed to evaluate the impact of walking with a pedometer on the sleep quality of postmenopausal Iranian women. Methods This randomized, controlled trial was conducted on 112 women who were randomly assigned to two groups. The women in the intervention group (n = 56) were asked to walk with a pedometer each day for 12 weeks and to increase their walking distance by 500 steps per week. A sociodemographic instrument and the Pittsburgh Sleep Quality Index were used to collect data. Sleep quality was measured at baseline, 4, 8, and 12 weeks after intervention. The control group (n = 56) did not receive any intervention. Results After 12 weeks, subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbances, use of sleeping medication, and daytime dysfunction improved to a significantly greater extent in the intervention group than in the control group (p < 0.05). The total sleep quality score was significantly higher in the intervention group than in the control group (0.64 vs. 0.98, p = 0.001). Conclusion This study showed that walking with a pedometer is an easy and cost-effective way to improve the quality of sleep among postmenopausal women. Use of this method in public health centers is recommended.

  15. Impact of pedometer-based walking on menopausal women's sleep quality: a randomized controlled trial.

    PubMed

    Tadayon, M; Abedi, P; Farshadbakht, F

    2016-08-01

    Objective Sleep disturbances are one of the most common psycho-physiological issues among postmenopausal women. This study was designed to evaluate the impact of walking with a pedometer on the sleep quality of postmenopausal Iranian women. Methods This randomized, controlled trial was conducted on 112 women who were randomly assigned to two groups. The women in the intervention group (n = 56) were asked to walk with a pedometer each day for 12 weeks and to increase their walking distance by 500 steps per week. A sociodemographic instrument and the Pittsburgh Sleep Quality Index were used to collect data. Sleep quality was measured at baseline, 4, 8, and 12 weeks after intervention. The control group (n = 56) did not receive any intervention. Results After 12 weeks, subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbances, use of sleeping medication, and daytime dysfunction improved to a significantly greater extent in the intervention group than in the control group (p < 0.05). The total sleep quality score was significantly higher in the intervention group than in the control group (0.64 vs. 0.98, p = 0.001). Conclusion This study showed that walking with a pedometer is an easy and cost-effective way to improve the quality of sleep among postmenopausal women. Use of this method in public health centers is recommended. PMID:26757356

  16. Walking speed and economic outcomes for walking-impaired patients with multiple sclerosis.

    PubMed

    Cohen, Joshua T

    2010-10-01

    This article estimates the impact of walking speed (measured using the Timed 25-Foot Walk [T25FW]) on three economic outcomes: productivity (annual earnings), care burden (value per year) and quality of life (utility score). Empirical data are not available to directly measure these relationships. Therefore, this article develops indirect estimates by characterizing the impact of the T25FW on the Expanded Disability Status Scale (EDSS), and the impact of the EDSS on economic outcomes. Use of the EDSS as a bridge introduces uncertainty, which precludes robust quantification of the relationship between walking speed and economic outcomes. Nonetheless, the analysis provides plausible ranges for the magnitude of these relationships. PMID:20950074

  17. Talk the Walk: Does Socio-Cognitive Resource Reallocation Facilitate the Development of Walking?

    PubMed

    Geva, Ronny; Orr, Edna

    2016-01-01

    Walking is of interest to psychology, robotics, zoology, neuroscience and medicine. Human's ability to walk on two feet is considered to be one of the defining characteristics of hominoid evolution. Evolutionary science propses that it emerged in response to limited environmental resources; yet the processes supporting its emergence are not fully understood. Developmental psychology research suggests that walking elicits cognitive advancements. We postulate that the relationship between cognitive development and walking is a bi-directional one; and further suggest that the initiation of novel capacities, such as walking, is related to internal socio-cognitive resource reallocation. We shed light on these notions by exploring infants' cognitive and socio-communicative outputs prospectively from 6-18 months of age. Structured bi/tri weekly evaluations of symbolic and verbal development were employed in an urban cohort (N = 9) for 12 months, during the transition from crawling to walking. Results show links between preemptive cognitive changes in socio-communicative output, symbolic-cognitive tool-use processes, and the age of emergence of walking. Plots of use rates of lower symbolic play levels before and after emergence of new skills illustrate reductions in use of previously attained key behaviors prior to emergence of higher symbolic play, language and walking. Further, individual differences in age of walking initiation were strongly related to the degree of reductions in complexity of object-use (r = .832, p < .005), along with increases, counter to the general reduction trend, in skills that serve recruitment of external resources [socio-communication bids before speech (r = -.696, p < .01), and speech bids before walking; r = .729, p < .01)]. Integration of these proactive changes using a computational approach yielded an even stronger link, underscoring internal resource reallocation as a facilitator of walking initiation (r = .901, p<0.001). These

  18. Talk the Walk: Does Socio-Cognitive Resource Reallocation Facilitate the Development of Walking?

    PubMed Central

    Orr, Edna

    2016-01-01

    Walking is of interest to psychology, robotics, zoology, neuroscience and medicine. Human’s ability to walk on two feet is considered to be one of the defining characteristics of hominoid evolution. Evolutionary science propses that it emerged in response to limited environmental resources; yet the processes supporting its emergence are not fully understood. Developmental psychology research suggests that walking elicits cognitive advancements. We postulate that the relationship between cognitive development and walking is a bi-directional one; and further suggest that the initiation of novel capacities, such as walking, is related to internal socio-cognitive resource reallocation. We shed light on these notions by exploring infants’ cognitive and socio-communicative outputs prospectively from 6–18 months of age. Structured bi/tri weekly evaluations of symbolic and verbal development were employed in an urban cohort (N = 9) for 12 months, during the transition from crawling to walking. Results show links between preemptive cognitive changes in socio-communicative output, symbolic-cognitive tool-use processes, and the age of emergence of walking. Plots of use rates of lower symbolic play levels before and after emergence of new skills illustrate reductions in use of previously attained key behaviors prior to emergence of higher symbolic play, language and walking. Further, individual differences in age of walking initiation were strongly related to the degree of reductions in complexity of object-use (r = .832, p < .005), along with increases, counter to the general reduction trend, in skills that serve recruitment of external resources [socio-communication bids before speech (r = -.696, p < .01), and speech bids before walking; r = .729, p < .01)]. Integration of these proactive changes using a computational approach yielded an even stronger link, underscoring internal resource reallocation as a facilitator of walking initiation (r = .901, p<0.001). These

  19. Effect of Geographic Distance on Distance Education: An Empirical Study

    ERIC Educational Resources Information Center

    Luo, Heng; Robinson, Anthony C.; Detwiler, Jim

    2014-01-01

    This study investigates the effect of geographic distance on students' distance learning experience with the aim to provide tentative answers to a fundamental question--does geographic distance matter in distance education? Using educational outcome data collected from an online master's program in Geographic Information Systems, this…

  20. Distance Training as Part of a Distance Consulting Solution.

    ERIC Educational Resources Information Center

    Fulantelli, Giovanni; Chiazzese, Giuseppe; Allegra, Mario

    "Distance Training" models, when integrated in a more complex framework, such as a "Distance Consulting" model, present specific features and impose a revision of the strategies commonly adopted in distance training experiences. This paper reports on the distance training strategies adopted in a European funded project aimed at defining and…

  1. Adaptation of neuromuscular activation patterns during treadmill walking after long-duration space flight

    NASA Astrophysics Data System (ADS)

    Layne, C. S.; Lange, G. W.; Pruett, C. J.; McDonald, P. V.; Merkle, L. A.; Mulavara, A. P.; Smith, S. L.; Kozlovskaya, I. B.; Bloomberg, J. J.

    The precise neuromuscular control needed for optimal locomotion, particularly around heel strike and toe off, is known to be compromised after short duration (8- to 15-day) space flight. We hypothesized here that longer exposure to weightlessness would result in maladaptive neuromuscular activation during postflight treadmill walking. We also hypothesized that space flight would affect the ability of the sensory-motor control system to generate adaptive neuromuscular activation patterns in response to changes in visual target distance during postflight treadmill walking. Seven crewmembers, who completed 3- to 6-month missions, walked on a motorized treadmill while visually fixating on a target placed 30 cm (NEAR) or 2 m (FAR) from the subject's eyes. Electronic foot switch data and surface electromyography were collected from selected muscles of the right lower limb. Results indicate that the phasic features of neuromuscular activation were moderately affected and the relative amplitude of activity in the tibialis anterior and rectus femoris around toe off changed after space flight. Changes also were evident after space flight in how these muscles adapted to the shift in visual target distance.

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

    MedlinePlus

    ... professionals. View the full list of resources ​​. Alternate Language URL Español Walking... A Step in the Right Direction Page Content What are the benefits of walking? Do I need to see a ...

  3. Random walk in generalized quantum theory

    SciTech Connect

    Martin, Xavier; O'Connor, Denjoe; Sorkin, Rafael D.

    2005-01-15

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

  4. The walk and jump of Equisetum spores.

    PubMed

    Marmottant, Philippe; Ponomarenko, Alexandre; Bienaimé, Diane

    2013-11-01

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

  5. Sunspot random walk and 22-year variation

    USGS Publications Warehouse

    Love, Jeffrey J.; Rigler, E. Joshua

    2012-01-01

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

  6. Random Walk Method for Potential Problems

    NASA Technical Reports Server (NTRS)

    Krishnamurthy, T.; Raju, I. S.

    2002-01-01

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

  7. Saccadic body turns in walking Drosophila

    PubMed Central

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

    2014-01-01

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

  8. Go Naked: Diapers Affect Infant Walking

    ERIC Educational Resources Information Center

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

    2012-01-01

    In light of cross-cultural and experimental research highlighting effects of childrearing practices on infant motor skill, we asked whether wearing diapers, a seemingly innocuous childrearing practice, affects infant walking. Diapers introduce bulk between the legs, potentially exacerbating infants' poor balance and wide stance. We show that…

  9. Measurements in the Levy quantum walk

    SciTech Connect

    Romanelli, A.

    2007-11-15

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

  10. Exploring Space and Place with Walking Interviews

    ERIC Educational Resources Information Center

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

    2008-01-01

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

  11. Random walk centrality for temporal networks

    NASA Astrophysics Data System (ADS)

    Rocha, Luis E. C.; Masuda, Naoki

    2014-06-01

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

  12. Myths about the Country Walk Case

    ERIC Educational Resources Information Center

    Cheit, Ross E.; Mervis, David

    2007-01-01

    The Country Walk case in Dade County, Florida was long considered a model for how to prosecute a multi-victim child sexual abuse case involving young children. In the past 10 years, however, a contrary view has emerged that the case was tainted by improper interviewing and was likely a false conviction. This is the first scholarly effort to assess…

  13. Autonomous exoskeleton reduces metabolic cost of walking.

    PubMed

    Mooney, Luke M; Rouse, Elliott J; Herr, Hugh M

    2014-01-01

    We developed an autonomous powered leg exoskeleton capable of providing large amounts of positive mechanical power to the wearer during powered plantarflexion phase of walking. The autonomous exoskeleton consisted of a winch actuator fasted to the shin which pulled on fiberglass struts attached to a boot. The fiberglass struts formed a rigid extension of the foot when the proximal end of the strut was pulled in forward by the winch actuator. This lightweight, geometric transmission allowed the electric winch actuator to efficiently produce biological levels of power at the ankle joint. The exoskeleton was powered and controlled by lithium polymer batteries and motor controller worn around the waist. Preliminary testing on two subjects walking at 1.4 m/s resulted in the exoskeleton reducing the metabolic cost of walking by 6-11% as compared to not wearing the device. The exoskeleton provided a peak mechanical power of over 180 W at each ankle (mean standard ± deviation) and an average positive mechanical power of 27 ± 1 W total to both ankles, while electrically using 75-89 W of electricity. The batteries (800 g) used in this experiment are estimated to be capable of providing this level of assistance for up to 7 km of walking. PMID:25570638

  14. Elementary Education: Elementary Students Simulate Moon Walk.

    ERIC Educational Resources Information Center

    Aviation/Space, 1980

    1980-01-01

    Describes the project of a fourth- and fifth-grade class in simulating a moon walk. Teams consisted of the astronauts, the life support team, the flight program team, the communications team, the scientific team, and the construction team. Their visit to the Marshall Space Flight Center is also described. (SA)

  15. Autonomous exoskeleton reduces metabolic cost of walking.

    PubMed

    Mooney, Luke M; Rouse, Elliott J; Herr, Hugh M

    2014-01-01

    We developed an autonomous powered leg exoskeleton capable of providing large amounts of positive mechanical power to the wearer during powered plantarflexion phase of walking. The autonomous exoskeleton consisted of a winch actuator fasted to the shin which pulled on fiberglass struts attached to a boot. The fiberglass struts formed a rigid extension of the foot when the proximal end of the strut was pulled in forward by the winch actuator. This lightweight, geometric transmission allowed the electric winch actuator to efficiently produce biological levels of power at the ankle joint. The exoskeleton was powered and controlled by lithium polymer batteries and motor controller worn around the waist. Preliminary testing on two subjects walking at 1.4 m/s resulted in the exoskeleton reducing the metabolic cost of walking by 6-11% as compared to not wearing the device. The exoskeleton provided a peak mechanical power of over 180 W at each ankle (mean standard ± deviation) and an average positive mechanical power of 27 ± 1 W total to both ankles, while electrically using 75-89 W of electricity. The batteries (800 g) used in this experiment are estimated to be capable of providing this level of assistance for up to 7 km of walking.

  16. The Physics of a Walking Robot

    ERIC Educational Resources Information Center

    Guemez, J.; Fiolhais, M.

    2013-01-01

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

  17. Sunspot random walk and 22-year variation

    NASA Astrophysics Data System (ADS)

    Love, Jeffrey J.; Rigler, E. Joshua

    2012-05-01

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

  18. Walking to School: Taking Research to Practice

    ERIC Educational Resources Information Center

    Heelan, Kate A.; Unruh, Scott A.; Combs, H. Jason; Donnelly, Joseph E.; Sutton, Sarah; Abbey, Bryce M.

    2008-01-01

    This article describes the results of a study that helped determine common barriers to active commuting to and from school, as well as the results of a Walking School Bus program that was implemented at two neighborhood elementary schools in Nebraska. While parental perceived barriers to active commuting may influence the travel choices of…

  19. Decelerating Environmentally Destructive Lawn-Walking

    ERIC Educational Resources Information Center

    Hayes, Steven C.; Cone, John D.

    1977-01-01

    Three general strategies were used to generate six interventions to decrease lawn walking in a park. While none of the three strategies appeared generally superior, some interventions were more effective than others. Another intervention, designed independently by professional planners, was also evaluated and shown to increase lawn walking…

  20. A Random Walk on a Circular Path

    ERIC Educational Resources Information Center

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

    2005-01-01

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