WorldWideScience

Sample records for stride frequency stride

  1. The importance of stride length and stride frequency in middle ...

    African Journals Online (AJOL)

    ... also found that the better runners have faster stride frequencies and that provincial middle distance runners use lower stride frequencies than international middle distance runners. Key Words: Biomechanics, stride length, stride frequency, maximum oxygen consumption, leg length, middle distance runners, road runners.

  2. Head and Tibial Acceleration as a Function of Stride Frequency and Visual Feedback during Running.

    Science.gov (United States)

    Busa, Michael A; Lim, Jongil; van Emmerik, Richard E A; Hamill, Joseph

    2016-01-01

    Individuals regulate the transmission of shock to the head during running at different stride frequencies although the consequences of this on head-gaze stability remain unclear. The purpose of this study was to examine if providing individuals with visual feedback of their head-gaze orientation impacts tibial and head accelerations, shock attenuation and head-gaze motion during preferred speed running at different stride frequencies. Fifteen strides from twelve recreational runners running on a treadmill at their preferred speed were collected during five stride frequencies (preferred, ±10% and ±20% of preferred) in two visual task conditions (with and without real-time visual feedback of head-gaze orientation). The main outcome measures were tibial and head peak accelerations assessed in the time and frequency domains, shock attenuation from tibia to head, and the magnitude and velocity of head-gaze motion. Decreasing stride frequency resulted in greater vertical accelerations of the tibia (pacceleration was only observed for the slowest stride frequency condition. Visual feedback resulted in reduced head acceleration magnitude (pacceleration within a wide range of stride frequencies; only at a stride frequency 20% below preferred did head acceleration increase. Furthermore, impact accelerations of the head and tibia appear to be solely a function of stride frequency as no differences were observed between feedback conditions. Increased visual task demands through head gaze feedback resulted in reductions in head accelerations in the active portion of stance and increased head-gaze stability.

  3. Comparison of accelerometry stride time calculation methods.

    Science.gov (United States)

    Norris, Michelle; Kenny, Ian C; Anderson, Ross

    2016-09-06

    Inertial sensors such as accelerometers and gyroscopes can provide a multitude of information on running gait. Running parameters such as stride time and ground contact time can all be identified within tibial accelerometry data. Within this, stride time is a popular parameter of interest, possibly due to its role in running economy. However, there are multiple methods utilised to derive stride time from tibial accelerometry data, some of which may offer complications when implemented on larger data files. Therefore, the purpose of this study was to compare previously utilised methods of stride time derivation to an original proposed method, utilising medio-lateral tibial acceleration data filtered at 2Hz, allowing for greater efficiency in stride time output. Tibial accelerometry data from six participants training for a half marathon were utilised. One right leg run was randomly selected for each participant, in which five consecutive running stride times were calculated. Four calculation methods were employed to derive stride time. A repeated measures analysis of variance (ANOVA) identified no significant difference in stride time between stride time calculation methods (p=1.00), whilst intra-class coefficient values (all >0.95) and coefficient of variance values (all method possibly offers a simplified technique for stride time output during running gait analysis. This method may be less influenced by "double peak" error and minor fluctuations within the data, allowing for accurate and efficient automated data output in both real time and post processing. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Effects of stride frequency and foot position at landing on braking force, hip torque, impact peak force and the metabolic cost of running in humans.

    Science.gov (United States)

    Lieberman, Daniel E; Warrener, Anna G; Wang, Justin; Castillo, Eric R

    2015-11-01

    Endurance runners are often advised to use 90 strides min(-1), but how optimal is this stride frequency and why? Endurance runners are also often advised to maintain short strides and avoid landing with the feet too far in front of their hips or knees (colloquially termed 'overstriding'), but how do different kinematic strategies for varying stride length at the same stride frequency affect economy and impact peaks? Linear mixed models were used to analyze repeated measures of stride frequency, the anteroposterior position of the foot at landing, V̇O2 , lower extremity kinematics and vertical ground reaction forces in 14 runners who varied substantially in height and body mass and who were asked to run at 75, 80, 85, 90 and 95 strides min(-1) at 3.0 m s(-1). For every increase of 5 strides min(-1), maximum hip flexor moments in the sagittal plane increased by 5.8% (Pbraking forces were associated with increases in foot landing position relative to the hip (P=0.0005) but not the knee (P=0.54); increases in foot landing position relative to the knee were associated with higher magnitudes (Pbraking forces versus maximum hip flexor moments during swing. The results suggest that runners may benefit from a stride frequency of approximately 85 strides min(-1) and by landing at the end of swing phase with a relatively vertical tibia. © 2015. Published by The Company of Biologists Ltd.

  5. Stride length: measuring its instantaneous value

    International Nuclear Information System (INIS)

    Campiglio, G C; Mazzeo, J R

    2007-01-01

    Human gait has been studied from different viewpoints: kinematics, dynamics, sensibility and others. Many of its characteristics still remain open to research, both for normal gait and for pathological gait. Objective measures of some of its most significant spatial/temporal parameters are important in this context. Stride length, one of these parameters, is defined as the distance between two consecutive contacts of one foot with ground. On this work we present a device designed to provide automatic measures of stride length. Its features make it particularly appropriate for the evaluation of pathological gait

  6. Changes in timing of muscle contractions and running economy with altered stride pattern during running.

    Science.gov (United States)

    Connick, Mark J; Li, Francois-Xavier

    2014-01-01

    Large alterations to the preferred running stride decrease running economy, and shorter strides increase leg muscle activity. However, the effect of altered strides on the timing of leg muscle activation is not known. The aim of this study was to evaluate the impact of moderate alterations to the running stride on running economy and the timing of biceps femoris (BF), vastus lateralis (VL) and gastrocnemius (GAST) muscle contractions. The preferred stride pattern for eleven trained male runners was measured prior to a separate visit where participants ran for bouts of 5 min whilst synchronising foot contacts to a metronome signal which was tuned to (1) the preferred stride, and (2) frequencies which related to ± 8% and ± 4% of the preferred stride length. Running economy was measured at each stride pattern along with electromyography and three-dimensional kinematics to estimate onset and offset of muscle contractions for each muscle. Running economy was greatest at the preferred stride length. However, a quadratic fit to the data was optimised at a stride which was 2.9% shorter than preferred. Onset and offset of BF and VL muscle contractions occurred earlier with shorter than preferred strides. We detected no changes to the timing of muscle contractions with longer than preferred strides and no changes to GAST muscle contractions. The results suggest that runners optimise running economy with a stride length that is close to, but shorter than, the preferred stride, and that timing of BF and VL muscle contractions change with shorter than preferred strides. Copyright © 2013 Elsevier B.V. All rights reserved.

  7. Stride time synergy in relation to walking during dual task

    DEFF Research Database (Denmark)

    Læssøe, Uffe; Madeleine, Pascal

    2012-01-01

    with a positive slope going through the mean of the strides, and bad variance with respect to a similar line with a negative slope. The general variance coefficient (CV%) was also computed. The effect of introducing a concurrent cognitive task (dual task: counting backwards in sequences of 7) was evaluated...... point of view elemental and performance variables may represent good and bad components of variability [2]. In this study we propose that the gait pattern can be seen as an on-going movement synergy in which each stride is corrected by the next stride (elemental variables) to ensure a steady gait...... (performance variable). AIM: The aim of this study was to evaluate stride time synergy and to identify good and bad stride variability in relation to walking during dual task. METHODS: Thirteen healthy young participants walked along a 2x5 meter figure-of-eight track at a self-selected comfortable speed...

  8. Stride angle as a novel indicator of running economy in well-trained runners.

    Science.gov (United States)

    Santos-Concejero, Jordan; Tam, Nicholas; Granados, Cristina; Irazusta, Jon; Bidaurrazaga-Letona, Iraia; Zabala-Lili, Jon; Gil, Susana M

    2014-07-01

    The main purpose of this study was to investigate the relationship between a novel biomechanical variable, the stride angle, and running economy (RE) in a homogeneous group of long-distance athletes. Twenty-five well-trained male runners completed 4-minute running stages on a treadmill at different set velocities. During the test, biomechanical variables such as stride angle, swing time, ground contact time, stride length, stride frequency, and the different sub-phases of ground contact were recorded using an optical measurement system. VO2 values at velocities below the lactate threshold were measured to calculate RE. Stride angle was negatively correlated with RE at every speed (p contact time and running performance according to the best 10-km race time (p ≤ 0.05, moderate and large effect sizes). Last, stride angle was correlated with ground contact time at every speed (p angle allows runners to minimize contact time during ground contact, whereby facilitating a better RE. Coaches and/or athletes may find stride angle a useful and easily obtainable measure to track and make alterations to running technique, because changes in stride angle may influence the energy cost of running and lead to improved performance.

  9. Stride length asymmetry in split-belt locomotion.

    Science.gov (United States)

    Hoogkamer, Wouter; Bruijn, Sjoerd M; Duysens, Jacques

    2014-01-01

    The number of studies utilizing a split-belt treadmill is rapidly increasing in recent years. This has led to some confusion regarding the definitions of reported gait parameters. The purpose of this paper is to clearly present the definitions of the gait parameters that are commonly used in split-belt treadmill studies. We argue that the modified version of stride length for split-belt gait, which is different from the standard definition of stride length and actually is a measure of limb excursion, should be referred to as 'limb excursion' in future studies. Furthermore, the symmetry of stride length and stride time is specifically addressed. Copyright © 2013 Elsevier B.V. All rights reserved.

  10. Stride time synergy in relation to walking during dual task

    DEFF Research Database (Denmark)

    Læssøe, Uffe; Madeleine, Pascal

    2012-01-01

    point of view elemental and performance variables may represent good and bad components of variability [2]. In this study we propose that the gait pattern can be seen as an on-going movement synergy in which each stride is corrected by the next stride (elemental variables) to ensure a steady gait...... (performance variable). AIM: The aim of this study was to evaluate stride time synergy and to identify good and bad stride variability in relation to walking during dual task. METHODS: Thirteen healthy young participants walked along a 2x5 meter figure-of-eight track at a self-selected comfortable speed....... RESULTS: The variance coefficient (CV%) increased significantly from 1.59 to 1.90 (psynergy approach, the good/bad variance ratio during single task was: 2.53 (CI95%: 2.07-3.00). When shifting to dual task the good/bad ratio was 2.28 (CI95...

  11. Adaptation and prosthesis effects on stride-to-stride fluctuations in amputee gait.

    Directory of Open Access Journals (Sweden)

    Shane R Wurdeman

    Full Text Available Twenty-four individuals with transtibial amputation were recruited to a randomized, crossover design study to examine stride-to-stride fluctuations of lower limb joint flexion/extension time series using the largest Lyapunov exponent (λ. Each individual wore a "more appropriate" and a "less appropriate" prosthesis design based on the subject's previous functional classification for a three week adaptation period. Results showed decreased λ for the sound ankle compared to the prosthetic ankle (F1,23 = 13.897, p = 0.001 and a decreased λ for the "more appropriate" prosthesis (F1,23 = 4.849, p = 0.038. There was also a significant effect for the time point in the adaptation period (F2,46 = 3.164, p = 0.050. Through the adaptation period, a freezing and subsequent freeing of dynamic degrees of freedom was seen as the λ at the ankle decreased at the midpoint of the adaptation period compared to the initial prosthesis fitting (p = 0.032, but then increased at the end compared to the midpoint (p = 0.042. No differences were seen between the initial fitting and the end of the adaptation for λ (p = 0.577. It is concluded that the λ may be a feasible clinical tool for measuring prosthesis functionality and adaptation to a new prosthesis is a process through which the motor control develops mastery of redundant degrees of freedom present in the system.

  12. GAIT DYNAMICS, FRACTALS AND FALLS: FINDING MEANING IN THE STRIDE-TO-STRIDE FLUCTUATIONS OF HUMAN WALKING

    Science.gov (United States)

    Hausdorff, Jeffrey M

    2007-01-01

    Until recently, quantitative studies of walking have typically focused on properties of a typical or average stride, ignoring the stride-to-stride fluctuations and considering these fluctuations to be noise. Work over the past two decades has demonstrated, however, that the alleged noise actually conveys important information. The magnitude of the stride-to-stride fluctuations and their changes over time during a walk – gait dynamics – may be useful in understanding the physiology of gait, in quantifying age-related and pathologic alterations in the locomotor control system, and in augmenting objective measurement of mobility and functional status Indeed, alterations in gait dynamics may help to determine disease severity, medication utility, and fall risk, and to objectively document improvements in response to therapeutic interventions, above and beyond what can be gleaned from measures based on the average, typical stride. This review discusses support for the idea that gait dynamics has meaning and may be useful in providing insight into the neural control of locomtion and for enhancing functional assessment of aging, chronic disease, and their impact on mobility. PMID:17618701

  13. Gait dynamics, fractals and falls: finding meaning in the stride-to-stride fluctuations of human walking.

    Science.gov (United States)

    Hausdorff, Jeffrey M

    2007-08-01

    Until recently, quantitative studies of walking have typically focused on properties of a typical or average stride, ignoring the stride-to-stride fluctuations and considering these fluctuations to be noise. Work over the past two decades has demonstrated, however, that the alleged noise actually conveys important information. The magnitude of the stride-to-stride fluctuations and their changes over time during a walk - gait dynamics - may be useful in understanding the physiology of gait, in quantifying age-related and pathologic alterations in the locomotor control system, and in augmenting objective measurement of mobility and functional status. Indeed, alterations in gait dynamics may help to determine disease severity, medication utility, and fall risk, and to objectively document improvements in response to therapeutic interventions, above and beyond what can be gleaned from measures based on the average, typical stride. This review discusses support for the idea that gait dynamics has meaning and may be useful in providing insight into the neural control of locomotion and for enhancing functional assessment of aging, chronic disease, and their impact on mobility.

  14. Precision and accuracy of the new XPrecia Stride mobile coagulometer.

    Science.gov (United States)

    Piacenza, Francesco; Galeazzi, Roberta; Cardelli, Maurizio; Moroni, Fausto; Provinciali, Mauro; Pierpaoli, Elisa; Giovagnetti, Simona; Appolloni, Stefania; Marchegiani, Francesca

    2017-08-01

    Oral anticoagulation therapy (OAT) with coumarins (vitamin K antagonist) is the most used against thromboembolism. Prothrombin time (PT) International Normalized Ratio (INR) monitoring is fundamental to establish coumarins dosage and prevent bleeding complications or thrombotic events. In this contest, the method and apparatus used for providing the INR measurements are crucial. Several studies have been published regarding the precision and accuracy of mobile coagulometers with different conclusions. No studies have been published regarding the new XPrecia Stride Mobile Coagulometer (Siemens). The aim of this work is to analyze precision and accuracy of the new XPrecia Stride mobile coagulometer to provide recommendations for clinical use and quality control. A total of 163 patients (mean age=77.4years old) under Warfarin OAT for whom the INR was assessed by both the traditional cs 2100i Sysmex and the new Xprecia Stride Mobile Coagulometer were included in this pilot study. The precision of the new mobile coagulometer resulted very good (CV15% from the true value in 20% of cases). Considering the overall results obtained by the new Xprecia Stride in comparison to that ones obtained from the other commercial devices, we can conclude that the new coagulometer is enough reliable for clinical settings. However, a larger trial to confirm these data is needed. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Strides towards substantive democracy and gender perspective in ...

    African Journals Online (AJOL)

    Strides towards substantive democracy and gender perspective in the 21st century of Africa. Kelvin Bribena. Abstract. The weakness of the multiparty political system in Africa will be analysed in line with accepted standards for transparency, electoral provisions, as well as the free and fair establishment, assembly and ...

  16. Extraction of stride events from gait accelerometry during treadmill walking.

    Science.gov (United States)

    Sejdić, Ervin; Lowry, Kristin A; Bellanca, Jennica; Perera, Subashan; Redfern, Mark S; Brach, Jennifer S

    Evaluating stride events can be valuable for understanding the changes in walking due to aging and neurological diseases. However, creating the time series necessary for this analysis can be cumbersome. In particular, finding heel contact and toe-off events which define the gait cycles accurately are difficult. We proposed a method to extract stride cycle events from tri-axial accelerometry signals. We validated our method via data collected from 14 healthy controls, 10 participants with Parkinson's disease and 11 participants with peripheral neuropathy. All participants walked at self-selected comfortable and reduced speeds on a computer-controlled treadmill. Gait accelerometry signals were captured via a tri-axial accelerometer positioned over the L3 segment of the lumbar spine. Motion capture data were also collected and served as the comparison method. Our analysis of the accelerometry data showed that the proposed methodology was able to accurately extract heel and toe contact events from both feet. We used t-tests, ANOVA and mixed models to summarize results and make comparisons. Mean gait cycle intervals were the same as those derived from motion capture and cycle-to-cycle variability measures were within 1.5%. Subject group differences could be identified similarly using measures with the two methods. A simple tri-axial acceleromter accompanied by a signal processing algorithm can be used to capture stride events. Clinical Impact: The proposed algorithm enables the assessment of stride events during treadmill walking, and is the first step towards the assessment of stride events using tri-axial accelerometers in real-life settings.

  17. Persistent fluctuations in stride intervals under fractal auditory stimulation.

    Science.gov (United States)

    Marmelat, Vivien; Torre, Kjerstin; Beek, Peter J; Daffertshofer, Andreas

    2014-01-01

    Stride sequences of healthy gait are characterized by persistent long-range correlations, which become anti-persistent in the presence of an isochronous metronome. The latter phenomenon is of particular interest because auditory cueing is generally considered to reduce stride variability and may hence be beneficial for stabilizing gait. Complex systems tend to match their correlation structure when synchronizing. In gait training, can one capitalize on this tendency by using a fractal metronome rather than an isochronous one? We examined whether auditory cues with fractal variations in inter-beat intervals yield similar fractal inter-stride interval variability as isochronous auditory cueing in two complementary experiments. In Experiment 1, participants walked on a treadmill while being paced by either an isochronous or a fractal metronome with different variation strengths between beats in order to test whether participants managed to synchronize with a fractal metronome and to determine the necessary amount of variability for participants to switch from anti-persistent to persistent inter-stride intervals. Participants did synchronize with the metronome despite its fractal randomness. The corresponding coefficient of variation of inter-beat intervals was fixed in Experiment 2, in which participants walked on a treadmill while being paced by non-isochronous metronomes with different scaling exponents. As expected, inter-stride intervals showed persistent correlations similar to self-paced walking only when cueing contained persistent correlations. Our results open up a new window to optimize rhythmic auditory cueing for gait stabilization by integrating fractal fluctuations in the inter-beat intervals.

  18. Pedestrian Stride Length Estimation from IMU Measurements and ANN Based Algorithm

    Directory of Open Access Journals (Sweden)

    Haifeng Xing

    2017-01-01

    Full Text Available Pedestrian dead reckoning (PDR can be used for continuous position estimation when satellite or other radio signals are not available, and the accuracy of the stride length measurement is important. Current stride length estimation algorithms, including linear and nonlinear models, consider a few variable factors, and some rely on high precision and high cost equipment. This paper puts forward a stride length estimation algorithm based on a back propagation artificial neural network (BP-ANN, using a consumer-grade inertial measurement unit (IMU; it then discusses various factors in the algorithm. The experimental results indicate that the error of the proposed algorithm in estimating the stride length is approximately 2%, which is smaller than that of the frequency and nonlinear models. Compared with the latter two models, the proposed algorithm does not need to determine individual parameters in advance if the trained neural net is effective. It can, thus, be concluded that this algorithm shows superior performance in estimating pedestrian stride length.

  19. Investigating the correlation between paediatric stride interval persistence and gross energy expenditure

    Directory of Open Access Journals (Sweden)

    Sejdić Ervin

    2010-02-01

    Full Text Available Abstract Background Stride interval persistence, a term used to describe the correlation structure of stride interval time series, is thought to provide insight into neuromotor control, though its exact clinical meaning has not yet been realized. Since human locomotion is shaped by energy efficient movements, it has been hypothesized that stride interval dynamics and energy expenditure may be inherently tied, both having demonstrated similar sensitivities to age, disease, and pace-constrained walking. Findings This study tested for correlations between stride interval persistence and measures of energy expenditure including mass-specific gross oxygen consumption per minute (, mass-specific gross oxygen cost per meter (VO2 and heart rate (HR. Metabolic and stride interval data were collected from 30 asymptomatic children who completed one 10-minute walking trial under each of the following conditions: (i overground walking, (ii hands-free treadmill walking, and (iii handrail-supported treadmill walking. Stride interval persistence was not significantly correlated with (p > 0.32, VO2 (p > 0.18 or HR (p > 0.56. Conclusions No simple linear dependence exists between stride interval persistence and measures of gross energy expenditure in asymptomatic children when walking overground and on a treadmill.

  20. Unfavorable Strides in Cache Memory Systems (RNR Technical Report RNR-92-015

    Directory of Open Access Journals (Sweden)

    David H. Bailey

    1995-01-01

    Full Text Available An important issue in obtaining high performance on a scientific application running on a cache-based computer system is the behavior of the cache when data are accessed at a constant stride. Others who have discussed this issue have noted an odd phenomenon in such situations: A few particular innocent-looking strides result in sharply reduced cache efficiency. In this article, this problem is analyzed, and a simple formula is presented that accurately gives the cache efficiency for various cache parameters and data strides.

  1. Select injury-related variables are affected by stride length and foot strike style during running.

    Science.gov (United States)

    Boyer, Elizabeth R; Derrick, Timothy R

    2015-09-01

    Some frontal plane and transverse plane variables have been associated with running injury, but it is not known if they differ with foot strike style or as stride length is shortened. To identify if step width, iliotibial band strain and strain rate, positive and negative free moment, pelvic drop, hip adduction, knee internal rotation, and rearfoot eversion differ between habitual rearfoot and habitual mid-/forefoot strikers when running with both a rearfoot strike (RFS) and a mid-/forefoot strike (FFS) at 3 stride lengths. Controlled laboratory study. A total of 42 healthy runners (21 habitual rearfoot, 21 habitual mid-/forefoot) ran overground at 3.35 m/s with both a RFS and a FFS at their preferred stride lengths and 5% and 10% shorter. Variables did not differ between habitual groups. Step width was 1.5 cm narrower for FFS, widening to 0.8 cm as stride length shortened. Iliotibial band strain and strain rate did not differ between foot strikes but decreased as stride length shortened (0.3% and 1.8%/s, respectively). Pelvic drop was reduced 0.7° for FFS compared with RFS, and both pelvic drop and hip adduction decreased as stride length shortened (0.8° and 1.5°, respectively). Peak knee internal rotation was not affected by foot strike or stride length. Peak rearfoot eversion was not different between foot strikes but decreased 0.6° as stride length shortened. Peak positive free moment (normalized to body weight [BW] and height [h]) was not affected by foot strike or stride length. Peak negative free moment was -0.0038 BW·m/h greater for FFS and decreased -0.0004 BW·m/h as stride length shortened. The small decreases in most variables as stride length shortened were likely associated with the concomitant wider step width. RFS had slightly greater pelvic drop, while FFS had slightly narrower step width and greater negative free moment. Shortening one's stride length may decrease or at least not increase propensity for running injuries based on the variables

  2. Effects of changing the random number stride in Monte Carlo calculations

    International Nuclear Information System (INIS)

    Hendricks, J.S.

    1991-01-01

    This paper reports on a common practice in Monte Carlo radiation transport codes which is to start each random walk a specified number of steps up the random number sequence from the previous one. This is called the stride in the random number sequence between source particles. It is used for correlated sampling or to provide tree-structured random numbers. A new random number generator algorithm for the major Monte Carlo code MCNP has been written to allow adjustment of the random number stride. This random number generator is machine portable. The effects of varying the stride for several sample problems are examined

  3. Altered fractal dynamics of gait: reduced stride-interval correlations with aging and Huntington's disease

    Science.gov (United States)

    Hausdorff, J. M.; Mitchell, S. L.; Firtion, R.; Peng, C. K.; Cudkowicz, M. E.; Wei, J. Y.; Goldberger, A. L.

    1997-01-01

    Fluctuations in the duration of the gait cycle (the stride interval) display fractal dynamics and long-range correlations in healthy young adults. We hypothesized that these stride-interval correlations would be altered by changes in neurological function associated with aging and certain disease states. To test this hypothesis, we compared the stride-interval time series of 1) healthy elderly subjects and young controls and of 2) subjects with Huntington's disease and healthy controls. Using detrended fluctuation analysis we computed alpha, a measure of the degree to which one stride interval is correlated with previous and subsequent intervals over different time scales. The scaling exponent alpha was significantly lower in elderly subjects compared with young subjects (elderly: 0.68 +/- 0.14; young: 0.87 +/- 0.15; P elderly subjects and in subjects with Huntington's disease. Abnormal alterations in the fractal properties of gait dynamics are apparently associated with changes in central nervous system control.

  4. Influence of contextual task constraints on preferred stride parameters and their variabilities during human walking.

    Science.gov (United States)

    Ojeda, Lauro V; Rebula, John R; Kuo, Arthur D; Adamczyk, Peter G

    2015-10-01

    Walking is not always a free and unencumbered task. Everyday activities such as walking in pairs, in groups, or on structured walkways can limit the acceptable gait patterns, leading to motor behavior that differs from that observed in more self-selected gait. Such different contexts may lead to gait performance different than observed in typical laboratory experiments, for example, during treadmill walking. We sought to systematically measure the impact of such task constraints by comparing gait parameters and their variability during walking in different conditions over-ground, and on a treadmill. We reconstructed foot motion from foot-mounted inertial sensors, and characterized forward, lateral and angular foot placement while subjects walked over-ground in a straight hallway and on a treadmill. Over-ground walking was performed in three variations: with no constraints (self-selected, SS); while deliberately varying walking speed (self-varied, SV); and while following a toy pace car programmed to vary speed (externally-varied, EV). We expected that these conditions would exhibit a statistically similar relationship between stride length and speed, and between stride length and stride period. We also expected treadmill walking (TM) would differ in two ways: first, that variability in stride length and stride period would conform to a constant-speed constraint opposite in slope from the normal relationship; and second, that stride length would decrease, leading to combinations of stride length and speed not observed in over-ground conditions. Results showed that all over-ground conditions used similar stride length-speed relationships, and that variability in treadmill walking conformed to a constant-speed constraint line, as expected. Decreased stride length was observed in both TM and EV conditions, suggesting adaptations due to heightened awareness or to prepare for unexpected changes or problems. We also evaluated stride variability in constrained and

  5. Knee Stretch Walking Method for Biped Robot: Using Toe and Heel Joints to Increase Walking Strides

    Science.gov (United States)

    Sato, Takahiko; Shimmyo, Shuhei; Nakazato, Miki; Mikami, Kei; Sato, Tomoya; Sakaino, Sho; Ohnishi, Kouhei

    This paper proposes a knee stretch walking method for biped robots; the method involves the use of the toes and heel joints to increase walking strides. A knee can be stretched by switching control variables. By a knee stretch walking with heel contacts to the ground and toe takeoffs from the ground, biped robots can increase their walking stride and speed. The validity of the proposed method is confirmed by simulation and experimental results.

  6. Gait variability and basal ganglia disorders: stride-to-stride variations of gait cycle timing in Parkinson's disease and Huntington's disease

    Science.gov (United States)

    Hausdorff, J. M.; Cudkowicz, M. E.; Firtion, R.; Wei, J. Y.; Goldberger, A. L.

    1998-01-01

    The basal ganglia are thought to play an important role in regulating motor programs involved in gait and in the fluidity and sequencing of movement. We postulated that the ability to maintain a steady gait, with low stride-to-stride variability of gait cycle timing and its subphases, would be diminished with both Parkinson's disease (PD) and Huntington's disease (HD). To test this hypothesis, we obtained quantitative measures of stride-to-stride variability of gait cycle timing in subjects with PD (n = 15), HD (n = 20), and disease-free controls (n = 16). All measures of gait variability were significantly increased in PD and HD. In subjects with PD and HD, gait variability measures were two and three times that observed in control subjects, respectively. The degree of gait variability correlated with disease severity. In contrast, gait speed was significantly lower in PD, but not in HD, and average gait cycle duration and the time spent in many subphases of the gait cycle were similar in control subjects, HD subjects, and PD subjects. These findings are consistent with a differential control of gait variability, speed, and average gait cycle timing that may have implications for understanding the role of the basal ganglia in locomotor control and for quantitatively assessing gait in clinical settings.

  7. Repeated sprint ability and stride kinematics are altered following an official match in national-level basketball players.

    Science.gov (United States)

    Delextrat, A; Baliqi, F; Clarke, N

    2013-04-01

    The aim of the study was to investigate the effects of playing an official national-level basketball match on repeated sprint ability (RSA) and stride kinematics. Nine male starting basketball players (22.8±2.2 years old, 191.3±5.8 cm, 88±10.3 kg, 12.3±4.6% body fat) volunteered to take part. Six repetitions of maximal 4-s sprints were performed on a non-motorised treadmill, separated by 21-s of passive recovery, before and immediately after playing an official match. Fluid loss, playing time, and the frequencies of the main match activities were recorded. The peak, mean, and performance decrement for average and maximal speed, acceleration, power, vertical and horizontal forces, and stride parameters were calculated over the six sprints. Differences between pre- and post-match were assessed by student t-tests. Significant differences between pre- and post-tests were observed in mean speed (-3.3%), peak and mean horizontal forces (-4.3% and -17.4%), peak and mean vertical forces (-3.4% and -3.7%), contact time (+7.3%), stride duration (+4.6%) and stride frequency (-4.0%), (Pvertical force were significantly correlated to fluid loss and sprint, jump and shuffle frequencies (P<0.05). These results highlight that the impairment in repeated sprint ability depends on the specific activities performed, and that replacing fluid loss through sweating during a match is crucial.

  8. Project Stride: An Equine-Assisted Intervention to Reduce Symptoms of Social Anxiety in Young Women.

    Science.gov (United States)

    Alfonso, Sarah V; Alfonso, Lauren A; Llabre, Maria M; Fernandez, M Isabel

    2015-01-01

    Although there is evidence supporting the use of equine-assisted activities to treat mental disorders, its efficacy in reducing signs and symptoms of social anxiety in young women has not been examined. We developed and pilot tested Project Stride, a brief, six-session intervention combining equine-assisted activities and cognitive-behavioral strategies to reduce symptoms of social anxiety. A total of 12 women, 18-29 years of age, were randomly assigned to Project Stride or a no-treatment control. Participants completed the Liebowitz Social Anxiety Scale at baseline, immediate-post, and 6 weeks after treatment. Project Stride was highly acceptable and feasible. Compared to control participants, those in Project Stride had significantly greater reductions in social anxiety scores from baseline to immediate-post [decrease of 24.8 points; t (9) = 3.40, P = .008)] and from baseline to follow-up [decrease of 31.8 points; t (9) = 4.12, P = .003)]. These findings support conducting a full-scale efficacy trial of Project Stride. Copyright © 2015 Elsevier Inc. All rights reserved.

  9. Leg heating and cooling influences running stride parameters but not running economy.

    Science.gov (United States)

    Folland, J P; Rowlands, D S; Thorp, R; Walmsley, A

    2006-10-01

    To evaluate the effect of temperature on running economy (RE) and stride parameters in 10 trained male runners (VO2peak 60.8 +/- 6.8 ml . kg (-1) . min (-1)), we used water immersion as a passive temperature manipulation to contrast localised pre-heating, pre-cooling, and thermoneutral interventions prior to running. Runners completed three 10-min treadmill runs at 70 % VO2peak following 40 min of randomised leg immersion in water at 21.0 degrees C (cold), 34.6 degrees C (thermoneutral), or 41.8 degrees C (hot). Treadmill runs were separated by 7 days. External respiratory gas exchange was measured for 30 s before and throughout the exercise and stride parameters were determined from video analysis in the sagittal plane. RE was not affected by prior heating or cooling with no difference in oxygen cost or energy expenditure between the temperature interventions (average VO2 3rd-10th min of exercise: C, 41.6 +/- 3.4 ml . kg (-1) . min (-1); TN, 41.6 +/- 3.0; H, 41.8 +/- 3.5; p = 0.94). Exercise heart rate was affected by temperature (H > TN > C; p exchange and minute ventilation/oxygen consumption ratios were greater in cold compared with thermoneutral (p economy despite changes in stride parameters that might indicate restricted muscle-tendon elasticity after pre-cooling. Larger changes in stride mechanics than those produced by the current temperature intervention are required to influence running economy.

  10. Stride Leg Ground Reaction Forces Predict Throwing Velocity in Adult Recreational Baseball Pitchers.

    Science.gov (United States)

    McNally, Michael P; Borstad, John D; Oñate, James A; Chaudhari, Ajit M W

    2015-10-01

    Ground reaction forces produced during baseball pitching have a significant impact in the development of ball velocity. However, the measurement of only one leg and small sample sizes in these studies curb the understanding of ground reaction forces as they relate to pitching. This study aimed to further clarify the role ground reaction forces play in developing pitching velocity. Eighteen former competitive baseball players with previous high school or collegiate pitching experience threw 15 fastballs from a pitcher's mound instrumented to measure ground reaction forces under both the drive and stride legs. Peak ground reaction forces were recorded during each phase of the pitching cycle, between peak knee height and ball release, in the medial/lateral, anterior/posterior, and vertical directions, and the peak resultant ground reaction force. Stride leg ground reaction forces during the arm-cocking and arm-acceleration phases were strongly correlated with ball velocity (r2 = 0.45-0.61), whereas drive leg ground reaction forces showed no significant correlations. Stepwise linear regression analysis found that peak stride leg ground reaction force during the arm-cocking phase was the best predictor of ball velocity (r2 = 0.61) among drive and stride leg ground reaction forces. This study demonstrates the importance of ground reaction force development in pitching, with stride leg forces being strongly predictive of ball velocity. Further research is needed to further clarify the role of ground reaction forces in pitching and to develop training programs designed to improve upper extremity mechanics and pitching performance through effective force development.

  11. A Novel Approach to Determine Strides, Ice Contact, and Swing Phases During Ice Hockey Skating Using a Single Accelerometer.

    Science.gov (United States)

    Stetter, Bernd J; Buckeridge, Erica; von Tscharner, Vinzenz; Nigg, Sandro R; Nigg, Benno M

    2016-02-01

    This study presents a new approach for automated identification of ice hockey skating strides and a method to detect ice contact and swing phases of individual strides by quantifying vibrations in 3D acceleration data during the blade-ice interaction. The strides of a 30-m forward sprinting task, performed by 6 ice hockey players, were evaluated using a 3D accelerometer fixed to a hockey skate. Synchronized plantar pressure data were recorded as reference data. To determine the accuracy of the new method on a range of forward stride patterns for temporal skating events, estimated contact times and stride times for a sequence of 5 consecutive strides was validated. Bland-Altman limits of agreement (95%) between accelerometer and plantar pressure derived data were less than 0.019 s. Mean differences between the 2 capture methods were shown to be less than 1 ms for contact and stride time. These results demonstrate the validity of the novel approach to determine strides, ice contact, and swing phases during ice hockey skating. This technology is accurate, simple, effective, and allows for in-field ice hockey testing.

  12. Increased gait variability may not imply impaired stride-to-stride control of walking in healthy older adults: Winner: 2013 Gait and Clinical Movement Analysis Society Best Paper Award.

    Science.gov (United States)

    Dingwell, Jonathan B; Salinas, Mandy M; Cusumano, Joseph P

    2017-06-01

    Older adults exhibit increased gait variability that is associated with fall history and predicts future falls. It is not known to what extent this increased variability results from increased physiological noise versus a decreased ability to regulate walking movements. To "walk", a person must move a finite distance in finite time, making stride length (L n ) and time (T n ) the fundamental stride variables to define forward walking. Multiple age-related physiological changes increase neuromotor noise, increasing gait variability. If older adults also alter how they regulate their stride variables, this could further exacerbate that variability. We previously developed a Goal Equivalent Manifold (GEM) computational framework specifically to separate these causes of variability. Here, we apply this framework to identify how both young and high-functioning healthy older adults regulate stepping from each stride to the next. Healthy older adults exhibited increased gait variability, independent of walking speed. However, despite this, these healthy older adults also concurrently exhibited no differences (all p>0.50) from young adults either in how their stride variability was distributed relative to the GEM or in how they regulated, from stride to stride, either their basic stepping variables or deviations relative to the GEM. Using a validated computational model, we found these experimental findings were consistent with increased gait variability arising solely from increased neuromotor noise, and not from changes in stride-to-stride control. Thus, age-related increased gait variability likely precedes impaired stepping control. This suggests these changes may in turn precede increased fall risk. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Making Strides

    Science.gov (United States)

    Jarrell, Andrea

    2013-01-01

    In the mad dash to complete the plethora of projects that lead up to the public launch of a campaign, it would be easy to start thinking of the kickoff as a goal in itself, but it's merely a mile marker in the marathon of a fundraising campaign that may last five to 10 years. Given that only a fraction of an institution's constituents may attend a…

  14. Stride length determination during overground running using a single foot-mounted inertial measurement unit.

    Science.gov (United States)

    Brahms, C Markus; Zhao, Yang; Gerhard, David; Barden, John M

    2018-02-10

    From a research perspective, detailed knowledge about stride length (SL) is important for coaches, clinicians and researchers because together with stride rate it determines the speed of locomotion. Moreover, individual SL vectors represent the integrated output of different biomechanical determinants and as such provide valuable insight into the control of running gait. In recent years, several studies have tried to estimate SL using body-mounted inertial measurement units (IMUs) and have reported promising results. However, many studies have used systems based on multiple sensors or have only focused on estimating SL for walking. Here we test the concurrent validity of a single foot-mounted, 9-degree of freedom IMU to estimate SL for running. We employed a running-specific, Kalman filter based zero-velocity update (ZUPT) algorithm to calculate individual SL vectors with the IMU and compared the results to SLs that were simultaneously recorded by a 6-camera 3D motion capture system. The results showed that the analytical procedures were able to successfully identify all strides that were recorded by the camera system and that excellent levels of absolute agreement (ICC(3,1) = 0.955) existed between the two methods. The findings demonstrate that individual SL vectors can be accurately estimated with a single foot-mounted IMU when running in a controlled laboratory setting. Copyright © 2018 Elsevier Ltd. All rights reserved.

  15. Effects of socks which improved foot sensation on velocity and stride length of elderly subjects crossing obstacles.

    Science.gov (United States)

    Yoo, Won-Gyu

    2015-08-01

    [Purpose] We developed socks which improve foot sensation and investigated their effect on the velocity and stride length of elderly women crossing obstacles. [Subjects] Ten community-dwelling, elderly women who could walk independently were recruited. [Methods] We measured velocity and stride length using the GAITRite system while the participants crossed obstacles under three conditions: barefoot, wearing ordinary socks, and wearing the socks which improve foot sensation. [Results] Velocity and stride length in bare feet and when wearing the sense-improving socks increased significantly compared to their values when wearing standard socks. Velocity and stride length did not differ between the bare foot and improved sock conditions. [Conclusion] Wearing socks helps protect the foot, but can decrease foot sensory input. Therefore, the socks which improve foot sensation were useful for preventing falls and protecting the feet of the elderly women while they crossed obstacles.

  16. Stride Segmentation during Free Walk Movements Using Multi-Dimensional Subsequence Dynamic Time Warping on Inertial Sensor Data

    Directory of Open Access Journals (Sweden)

    Jens Barth

    2015-03-01

    Full Text Available Changes in gait patterns provide important information about individuals’ health. To perform sensor based gait analysis, it is crucial to develop methodologies to automatically segment single strides from continuous movement sequences. In this study we developed an algorithm based on time-invariant template matching to isolate strides from inertial sensor signals. Shoe-mounted gyroscopes and accelerometers were used to record gait data from 40 elderly controls, 15 patients with Parkinson’s disease and 15 geriatric patients. Each stride was manually labeled from a straight 40 m walk test and from a video monitored free walk sequence. A multi-dimensional subsequence Dynamic Time Warping (msDTW approach was used to search for patterns matching a pre-defined stride template constructed from 25 elderly controls. F-measure of 98% (recall 98%, precision 98% for 40 m walk tests and of 97% (recall 97%, precision 97% for free walk tests were obtained for the three groups. Compared to conventional peak detection methods up to 15% F-measure improvement was shown. The msDTW proved to be robust for segmenting strides from both standardized gait tests and free walks. This approach may serve as a platform for individualized stride segmentation during activities of daily living.

  17. The operational implications of donor behaviors following enrollment in STRIDE (Strategies to Reduce Iron Deficiency in blood donors).

    Science.gov (United States)

    Cable, Ritchard G; Birch, Rebecca J; Spencer, Bryan R; Wright, David J; Bialkowski, Walter; Kiss, Joseph E; Rios, Jorge; Bryant, Barbara J; Mast, Alan E

    2017-10-01

    Donor behaviors in STRIDE (Strategies to Reduce Iron Deficiency), a trial to reduce iron deficiency, were examined. Six hundred ninety-two frequent donors were randomized to receive either 19 or 38 mg iron for 60 days or an educational letter based on their predonation ferritin. Compliance with assigned pills, response to written recommendations, change in donation frequency, and future willingness to take iron supplements were examined. Donors who were randomized to receive iron pills had increased red blood cell donations and decreased hemoglobin deferrals compared with controls or with pre-STRIDE donations. Donors who were randomized to receive educational letters had fewer hemoglobin deferrals compared with controls. Of those who received a letter advising of low ferritin levels with recommendations to take iron supplements or delay future donations, 57% reported that they initiated iron supplementation, which was five times as many as those who received letters lacking a specific recommendation. The proportion reporting delayed donation was not statistically different (32% vs. 20%). Of donors who were assigned pills, 58% reported taking them "frequently," and forgetting was the primary reason for non-compliance. Approximately 80% of participants indicated that they would take iron supplements if provided by the center. Donors who were assigned iron pills had acceptable compliance, producing increased red blood cell donations and decreased low hemoglobin deferrals compared with controls or with pre-STRIDE rates. The majority of donors assigned to an educational letter took action after receiving a low ferritin result, with more donors choosing to take iron than delay donation. Providing donors with information on iron status with personalized recommendations was an effective alternative to directly providing iron supplements. © 2017 AABB.

  18. Running-specific, periodized strength training attenuates loss of stride length during intense endurance running.

    Science.gov (United States)

    Esteve-Lanao, Jonathan; Rhea, Matthew R; Fleck, Steven J; Lucia, Alejandro

    2008-07-01

    The purpose of this study was to determine the effects of a running-specific, periodized strength training program (performed over the specific period [8 weeks] of a 16-week macrocycle) on endurance-trained runners' capacity to maintain stride length during running bouts at competitive speeds. Eighteen well-trained middle-distance runners completed the study (personal bests for 1500 and 5000 m of 3 minutes 57 seconds +/- 12 seconds and 15 minutes 24 seconds +/- 36 seconds). They were randomly assigned to each of the following groups (6 per group): periodized strength group, performing a periodized strength training program over the 8-week specific (intervention) period (2 sessions per week); nonperiodized strength group, performing the same strength training exercises as the periodized group over the specific period but with no week-to-week variations; and a control group, performing no strength training at all during the specific period. The percentage of loss in the stride length (cm)/speed (m.s) (SLS) ratio was measured by comparing the mean SLS during the first and third (last) group of the total repetitions, respectively, included in each of the interval training sessions performed at race speeds during the competition period that followed the specific period. Significant differences (p endurance runners during fatiguing running bouts.

  19. Effect of treadmill versus overground running on the structure of variability of stride timing.

    Science.gov (United States)

    Lindsay, Timothy R; Noakes, Timothy D; McGregor, Stephen J

    2014-04-01

    Gait timing dynamics of treadmill and overground running were compared. Nine trained runners ran treadmill and track trials at 80, 100, and 120% of preferred pace for 8 min. each. Stride time series were generated for each trial. To each series, detrended fluctuation analysis (DFA), power spectral density (PSD), and multiscale entropy (MSE) analysis were applied to infer the regime of control along the randomness-regularity axis. Compared to overground running, treadmill running exhibited a higher DFA and PSD scaling exponent, as well as lower entropy at non-preferred speeds. This indicates a more ordered control for treadmill running, especially at non-preferred speeds. The results suggest that the treadmill itself brings about greater constraints and requires increased voluntary control. Thus, the quantification of treadmill running gait dynamics does not necessarily reflect movement in overground settings.

  20. Longitudinal assessment of neuropsychological and temporal/spatial gait characteristics of elderly fallers: taking it all in stride

    Directory of Open Access Journals (Sweden)

    Rebecca K MacAulay

    2015-03-01

    Full Text Available Gait abnormalities are linked to cognitive decline and an increased fall risk within older adults. The present study addressed gaps from cross-sectional studies in the literature by longitudinally examining the interplay between temporal and spatial aspects of gait, cognitive function, age, and lower-extremity strength in elderly fallers and non-fallers. Gait characteristics, neuropsychological and physical test performance were examined at two time points spaced a year apart in cognitively intact individuals aged 60 and older (N = 416. Mixed-model repeated-measure ANCOVAs examined temporal (step time and spatial (stride length gait characteristics during a simple and cognitive-load walking task in fallers as compared to non-fallers. Fallers consistently demonstrated significant alterations in spatial, but not temporal, aspects of gait as compared to non-fallers during both walking tasks. Step time became slower as stride length shortened amongst all participants during the dual task. Shorter strides and slower step times during the dual task were both predicted by worse executive attention/processing speed performance. In summary, divided attention significantly impacts spatial aspects of gait in fallers, suggesting stride length changes may precede declines in other neuropsychological and gait characteristics, thereby selectively increasing fall risk. Our results indicate that multimodal intervention approaches that integrate physical and cognitive remediation strategies may increase the effectiveness of fall risk interventions.

  1. Analysis and Classification of Stride Patterns Associated with Children Development Using Gait Signal Dynamics Parameters and Ensemble Learning Algorithms

    Directory of Open Access Journals (Sweden)

    Meihong Wu

    2016-01-01

    Full Text Available Measuring stride variability and dynamics in children is useful for the quantitative study of gait maturation and neuromotor development in childhood and adolescence. In this paper, we computed the sample entropy (SampEn and average stride interval (ASI parameters to quantify the stride series of 50 gender-matched children participants in three age groups. We also normalized the SampEn and ASI values by leg length and body mass for each participant, respectively. Results show that the original and normalized SampEn values consistently decrease over the significance level of the Mann-Whitney U test (p<0.01 in children of 3–14 years old, which indicates the stride irregularity has been significantly ameliorated with the body growth. The original and normalized ASI values are also significantly changing when comparing between any two groups of young (aged 3–5 years, middle (aged 6–8 years, and elder (aged 10–14 years children. Such results suggest that healthy children may better modulate their gait cadence rhythm with the development of their musculoskeletal and neurological systems. In addition, the AdaBoost.M2 and Bagging algorithms were used to effectively distinguish the children’s gait patterns. These ensemble learning algorithms both provided excellent gait classification results in terms of overall accuracy (≥90%, recall (≥0.8, and precision (≥0.8077.

  2. Is walking a random walk? Evidence for long-range correlations in stride interval of human gait

    Science.gov (United States)

    Hausdorff, Jeffrey M.; Peng, C.-K.; Ladin, Zvi; Wei, Jeanne Y.; Goldberger, Ary L.

    1995-01-01

    Complex fluctuation of unknown origin appear in the normal gait pattern. These fluctuations might be described as being (1) uncorrelated white noise, (2) short-range correlations, or (3) long-range correlations with power-law scaling. To test these possibilities, the stride interval of 10 healthy young men was measured as they walked for 9 min at their usual rate. From these time series we calculated scaling indexes by using a modified random walk analysis and power spectral analysis. Both indexes indicated the presence of long-range self-similar correlations extending over hundreds of steps; the stride interval at any time depended on the stride interval at remote previous times, and this dependence decayed in a scale-free (fractallike) power-law fashion. These scaling indexes were significantly different from those obtained after random shuffling of the original time series, indicating the importance of the sequential ordering of the stride interval. We demonstrate that conventional models of gait generation fail to reproduce the observed scaling behavior and introduce a new type of central pattern generator model that sucessfully accounts for the experimentally observed long-range correlations.

  3. Increased delivery stride length places greater loads on the ankle joint in elite male cricket fast bowlers.

    Science.gov (United States)

    Spratford, Wayne; Hicks, Amy

    2014-01-01

    The purpose of this study was to investigate the effect stride length has on ankle biomechanics of the leading leg with reference to the potential risk of injury in cricket fast bowlers. Ankle joint kinematic and kinetic data were collected from 51 male fast bowlers during the stance phase of the final delivery stride. The bowling cohort comprised national under-19, first class and international-level athletes. Bowlers were placed into either Short, Average or Long groups based on final stride length, allowing statistical differences to be measured. A multivariate analysis of variance with a Bonferroni post-hoc correction (α = 0.05) revealed significant differences between peak plantarflexion angles (Short-Long P = 0.005, Average and Long P = 0.04) and negative joint work (Average-Long P = 0.026). This study highlighted that during fast bowling the ankle joint of the leading leg experiences high forces under wide ranges of movement. As stride length increases, greater amounts of negative work and plantarflexion are experienced. These increases place greater loads on the ankle joint and move the foot into positions that make it more susceptible to injuries such as posterior impingement syndrome.

  4. Validation of distal limb mounted inertial-measurement-unit sensors for stride detection in Warmblood horses at walk and trot

    NARCIS (Netherlands)

    Serra Braganca, Filipe; Bosch, S; Voskamp, J P; Marin-Perianu, M; Van der Zwaag, B J; Vernooij, J C M; van Weeren, P R; Back, W

    BACKGROUND: Inertial-measurement-unit (IMU)-sensor-based techniques are becoming more popular in horses as a tool for objective locomotor assessment. OBJECTIVES: To describe, evaluate and validate a method of stride detection and quantification at walk and trot using distal limb mounted IMU-sensors.

  5. Validation of Distal Limb Mounted Imu Sensors for Stride Detection and Locomotor Quantification in Warmblood Horses at Walk and Trot

    NARCIS (Netherlands)

    Serra Braganca, F.M.; Vernooij, J.C.M.; René van Weeren, P.; Back, Wim

    Reasons for performing study: IMU-sensor based techniques arebecoming more popular in horses as a tool for objective locomotorassessment. Using currently proposed methods only limited informationabout stride variables can be obtained for walk and trot.Objectives: To describe, evaluate and validate a

  6. Validation of distal limb mounted inertial measurement unit sensors for stride detection in Warmblood horses at walk and trot

    NARCIS (Netherlands)

    Braganca, F.M.; Bosch, S.; Voskamp, J.P.; Marin Perianu, Mihai; van der Zwaag, B.J.; Vernooij, J.C.; van Weeren, P.R.; Back, W.

    2016-01-01

    Background: Inertial measurement unit (IMU) sensor-based techniques are becoming more popular in horses as a tool for objective locomotor assessment. Objectives: To describe, evaluate and validate a method of stride detection and quantification at walk and trot using distal limb mounted IMU sensors.

  7. Impact of stride-coupled gaze shifts of walking blowflies on the neuronal representation of visual targets

    Directory of Open Access Journals (Sweden)

    Daniel eKress

    2014-09-01

    Full Text Available During locomotion animals rely heavily on visual cues gained from the environment to guide their behavior. Examples are basic behaviors like collision avoidance or the approach to a goal. The saccadic gaze strategy of flying flies, which separates translational from rotational phases of locomotion, has been suggested to facilitate the extraction of environmental information, because only image flow evoked by translational self-motion contains relevant distance information about the surrounding world. In contrast to the translational phases of flight during which gaze direction is kept largely constant, walking flies experience continuous rotational image flow that is coupled to their stride-cycle. The consequences of these self-produced image shifts for the extraction of environmental information are still unclear. To assess the impact of stride-coupled image shifts on visual information processing, we performed electrophysiological recordings from the HSE cell, a motion sensitive wide-field neuron in the blowfly visual system. This cell has been concluded to play a key role in mediating optomotor behavior, self-motion estimation and spatial information processing. We used visual stimuli that were based on the visual input experienced by walking blowflies while approaching a black vertical bar. The response of HSE to these stimuli was dominated by periodic membrane potential fluctuations evoked by stride-coupled image shifts. Nevertheless, during the approach the cell’s response contained information about the bar and its background. The response components evoked by the bar were larger than the responses to its background, especially during the last phase of the approach. However, as revealed by targeted modifications of the visual input during walking, the extraction of distance information on the basis of HSE responses is much impaired by stride-coupled retinal image shifts. Possible mechanisms that may cope with these stride

  8. The STRIDE weight loss and lifestyle intervention for individuals taking antipsychotic medications: a randomized trial.

    Science.gov (United States)

    Green, Carla A; Yarborough, Bobbi Jo H; Leo, Michael C; Yarborough, Micah T; Stumbo, Scott P; Janoff, Shannon L; Perrin, Nancy A; Nichols, Greg A; Stevens, Victor J

    2015-01-01

    The STRIDE study assessed whether a lifestyle intervention, tailored for individuals with serious mental illnesses, reduced weight and diabetes risk. The authors hypothesized that the STRIDE intervention would be more effective than usual care in reducing weight and improving glucose metabolism. The study design was a multisite, parallel two-arm randomized controlled trial in community settings and an integrated health plan. Participants who met inclusion criteria were ≥18 years old, were taking antipsychotic agents for ≥30 days, and had a body mass index ≥27. Exclusions were significant cognitive impairment, pregnancy/breastfeeding, recent psychiatric hospitalization, bariatric surgery, cancer, heart attack, or stroke. The intervention emphasized moderate caloric reduction, the DASH (Dietary Approaches to Stop Hypertension) diet, and physical activity. Blinded staff collected data at baseline, 6 months, and 12 months. Participants (men, N=56; women, N=144; mean age=47.2 years [SD=10.6]) were randomly assigned to usual care (N=96) or a 6-month weekly group intervention plus six monthly maintenance sessions (N=104). A total of 181 participants (90.5%) completed 6-month assessments, and 170 (85%) completed 12-month assessments, without differential attrition. Participants attended 14.5 of 24 sessions over 6 months. Intent-to-treat analyses revealed that intervention participants lost 4.4 kg more than control participants from baseline to 6 months (95% CI=-6.96 kg to -1.78 kg) and 2.6 kg more than control participants from baseline to 12 months (95% CI=-5.14 kg to -0.07 kg). At 12 months, fasting glucose levels in the control group had increased from 106.0 mg/dL to 109.5 mg/dL and decreased in the intervention group from 106.3 mg/dL to 100.4 mg/dL. No serious adverse events were study-related; medical hospitalizations were reduced in the intervention group (6.7%) compared with the control group (18.8%). Individuals taking antipsychotic medications can lose

  9. Stimulant Reduction Intervention using Dosed Exercise (STRIDE - CTN 0037: Study protocol for a randomized controlled trial

    Directory of Open Access Journals (Sweden)

    Morris David W

    2011-09-01

    Full Text Available Abstract Background There is a need for novel approaches to the treatment of stimulant abuse and dependence. Clinical data examining the use of exercise as a treatment for the abuse of nicotine, alcohol, and other substances suggest that exercise may be a beneficial treatment for stimulant abuse, with direct effects on decreased use and craving. In addition, exercise has the potential to improve other health domains that may be adversely affected by stimulant use or its treatment, such as sleep disturbance, cognitive function, mood, weight gain, quality of life, and anhedonia, since it has been shown to improve many of these domains in a number of other clinical disorders. Furthermore, neurobiological evidence provides plausible mechanisms by which exercise could positively affect treatment outcomes. The current manuscript presents the rationale, design considerations, and study design of the National Institute on Drug Abuse (NIDA Clinical Trials Network (CTN CTN-0037 Stimulant Reduction Intervention using Dosed Exercise (STRIDE study. Methods/Design STRIDE is a multisite randomized clinical trial that compares exercise to health education as potential treatments for stimulant abuse or dependence. This study will evaluate individuals diagnosed with stimulant abuse or dependence who are receiving treatment in a residential setting. Three hundred and thirty eligible and interested participants who provide informed consent will be randomized to one of two treatment arms: Vigorous Intensity High Dose Exercise Augmentation (DEI or Health Education Intervention Augmentation (HEI. Both groups will receive TAU (i.e., usual care. The treatment arms are structured such that the quantity of visits is similar to allow for equivalent contact between groups. In both arms, participants will begin with supervised sessions 3 times per week during the 12-week acute phase of the study. Supervised sessions will be conducted as one-on-one (i.e., individual sessions

  10. Endüstride Su Güvenliği, Dezenfeksiyon ve Sanitasyonu

    Directory of Open Access Journals (Sweden)

    Ayla ÜNVER

    2011-01-01

    Full Text Available Gelişmekte olan ülkelerde, her yıl suyla bulaşan hastalıklar yüzünden milyonlarca kişi ölmekte, milyarlarca kişi de hasta olmaktadır. Dünya nüfusunun artması sonucu, içme ve kullanma suyu ihtiyacı hızla artmıştır. Ayrıca çevre kirliliği su kaynaklarında kirlenmeye sebep olmuştur. Su endüstride en çok kullanılan hammaddelerden biridir. Su kalitesi standartları ülke yönetimleri ve uluslararası standartlarca belirlenir. Suyun saflaştırılması; istenmeyen kimyasalların, diğer materyallerin ve biyolojik kontaminantların sudan uzaklaştırılması prosesidir. Su saflaştırma, sağlıklı dağıtım sistemleri, su dezenfeksiyon prosesleri, medikal, gıda sektörü, kimyasal ve endüstriyel uygulamalar için önemli gerekliliklerdir.

  11. Walking training with cueing of cadence improves walking speed and stride length after stroke more than walking training alone: a systematic review.

    Science.gov (United States)

    Nascimento, Lucas R; de Oliveira, Camila Quel; Ada, Louise; Michaelsen, Stella M; Teixeira-Salmela, Luci F

    2015-01-01

    After stroke, is walking training with cueing of cadence superior to walking training alone in improving walking speed, stride length, cadence and symmetry? Systematic review with meta-analysis of randomised or controlled trials. Adults who have had a stroke. Walking training with cueing of cadence. Four walking outcomes were of interest: walking speed, stride length, cadence and symmetry. This review included seven trials involving 211 participants. Because one trial caused substantial statistical heterogeneity, meta-analyses were conducted with and without this trial. Walking training with cueing of cadence improved walking speed by 0.23 m/s (95% CI 0.18 to 0.27, I(2)=0%), stride length by 0.21 m (95% CI 0.14 to 0.28, I(2)=18%), cadence by 19 steps/minute (95% CI 14 to 23, I(2)=40%), and symmetry by 15% (95% CI 3 to 26, random effects) more than walking training alone. This review provides evidence that walking training with cueing of cadence improves walking speed and stride length more than walking training alone. It may also produce benefits in terms of cadence and symmetry of walking. The evidence appears strong enough to recommend the addition of 30 minutes of cueing of cadence to walking training, four times a week for 4 weeks, in order to improve walking in moderately disabled individuals with stroke. PROSPERO (CRD42013005873). Copyright © 2014 Australian Physiotherapy Association. Published by Elsevier B.V. All rights reserved.

  12. Recommended number of strides for automatic assessment of gait symmetry and regularity in above-knee amputees by means of accelerometry and autocorrelation analysis

    Directory of Open Access Journals (Sweden)

    Tura Andrea

    2012-02-01

    Full Text Available Abstract Background Symmetry and regularity of gait are essential outcomes of gait retraining programs, especially in lower-limb amputees. This study aims presenting an algorithm to automatically compute symmetry and regularity indices, and assessing the minimum number of strides for appropriate evaluation of gait symmetry and regularity through autocorrelation of acceleration signals. Methods Ten transfemoral amputees (AMP and ten control subjects (CTRL were studied. Subjects wore an accelerometer and were asked to walk for 70 m at their natural speed (twice. Reference values of step and stride regularity indices (Ad1 and Ad2 were obtained by autocorrelation analysis of the vertical and antero-posterior acceleration signals, excluding initial and final strides. The Ad1 and Ad2 coefficients were then computed at different stages by analyzing increasing portions of the signals (considering both the signals cleaned by initial and final strides, and the whole signals. At each stage, the difference between Ad1 and Ad2 values and the corresponding reference values were compared with the minimum detectable difference, MDD, of the index. If that difference was less than MDD, it was assumed that the portion of signal used in the analysis was of sufficient length to allow reliable estimation of the autocorrelation coefficient. Results All Ad1 and Ad2 indices were lower in AMP than in CTRL (P Conclusions Without the need to identify and eliminate the phases of gait initiation and termination, twenty strides can provide a reasonable amount of information to reliably estimate gait regularity in transfemoral amputees.

  13. Validation of distal limb mounted inertial measurement unit sensors for stride detection in Warmblood horses at walk and trot.

    Science.gov (United States)

    Bragança, F M; Bosch, S; Voskamp, J P; Marin-Perianu, M; Van der Zwaag, B J; Vernooij, J C M; van Weeren, P R; Back, W

    2017-07-01

    Inertial measurement unit (IMU) sensor-based techniques are becoming more popular in horses as a tool for objective locomotor assessment. To describe, evaluate and validate a method of stride detection and quantification at walk and trot using distal limb mounted IMU sensors. Prospective validation study comparing IMU sensors and motion capture with force plate data. A total of seven Warmblood horses equipped with metacarpal/metatarsal IMU sensors and reflective markers for motion capture were hand walked and trotted over a force plate. Using four custom built algorithms hoof-on/hoof-off timing over the force plate were calculated for each trial from the IMU data. Accuracy of the computed parameters was calculated as the mean difference in milliseconds between the IMU or motion capture generated data and the data from the force plate, precision as the s.d. of these differences and percentage of error with accuracy of the calculated parameter as a percentage of the force plate stance duration. Accuracy, precision and percentage of error of the best performing IMU algorithm for stance duration at walk were 28.5, 31.6 ms and 3.7% for the forelimbs and -5.5, 20.1 ms and -0.8% for the hindlimbs, respectively. At trot the best performing algorithm achieved accuracy, precision and percentage of error of -27.6/8.8 ms/-8.4% for the forelimbs and 6.3/33.5 ms/9.1% for the hindlimbs. The described algorithms have not been assessed on different surfaces. Inertial measurement unit technology can be used to determine temporal kinematic stride variables at walk and trot justifying its use in gait and performance analysis. However, precision of the method may not be sufficient to detect all possible lameness-related changes. These data seem promising enough to warrant further research to evaluate whether this approach will be useful for appraising the majority of clinically relevant gait changes encountered in practice. © 2016 The Authors. Equine Veterinary Journal published by

  14. The Effect of the Accelerometer Operating Range on Biomechanical Parameters: Stride Length, Velocity, and Peak Tibial Acceleration during Running

    Directory of Open Access Journals (Sweden)

    Christian Mitschke

    2018-01-01

    Full Text Available Previous studies have used accelerometers with various operating ranges (ORs when measuring biomechanical parameters. However, it is still unclear whether ORs influence the accuracy of running parameters, and whether the different stiffnesses of footwear midsoles influence this accuracy. The purpose of the present study was to systematically investigate the influence of OR on the accuracy of stride length, running velocity, and on peak tibial acceleration. Twenty-one recreational heel strike runners ran on a 15-m indoor track at self-selected running speeds in three footwear conditions (low to high midsole stiffness. Runners were equipped with an inertial measurement unit (IMU affixed to the heel cup of the right shoe and with a uniaxial accelerometer at the right tibia. Accelerometers (at the tibia and included in the IMU with a high OR of ±70 g were used as the reference and the data were cut at ±32, ±16, and at ±8 g in post-processing, before calculating parameters. The results show that the OR influenced the outcomes of all investigated parameters, which were not influenced by tested footwear conditions. The lower ORs were associated with an underestimation error for all biomechanical parameters, which increased noticeably with a decreasing OR. It can be concluded that accelerometers with a minimum OR of ±32 g should be used to avoid inaccurate measurements.

  15. Assessing Stride Variables and Vertical Stiffness with GPS-Embedded Accelerometers: Preliminary Insights for the Monitoring of Neuromuscular Fatigue on the Field

    Directory of Open Access Journals (Sweden)

    Martin Buchheit, Andrew Gray, Jean-Benoit Morin

    2015-12-01

    Full Text Available The aim of the present study was to examine the ability of a GPS-imbedded accelerometer to assess stride variables and vertical stiffness (K, which are directly related to neuromuscular fatigue during field-based high-intensity runs. The ability to detect stride imbalances was also examined. A team sport player performed a series of 30-s runs on an instrumented treadmill (6 runs at 10, 17 and 24 km·h-1 with or without his right ankle taped (aimed at creating a stride imbalance, while wearing on his back a commercially-available GPS unit with an embedded 100-Hz tri-axial accelerometer. Contact (CT and flying (FT time, and K were computed from both treadmill and accelerometers (Athletic Data Innovations data. The agreement between treadmill (criterion measure and accelerometer-derived data was examined. We also compared the ability of the different systems to detect the stride imbalance. Biases were small (CT and K and moderate (FT. The typical error of the estimate was trivial (CT, small (K and moderate (FT, with nearly perfect (CT and K and large (FT correlations for treadmill vs. accelerometer. The tape induced very large increase in the right - left foot ∆ in CT, FT and K measured by the treadmill. The tape effect on CT and K ∆ measured with the accelerometers were also very large, but of lower magnitude than with the treadmill. The tape effect on accelerometer-derived ∆ FT was unclear. Present data highlight the potential of a GPS-embedded accelerometer to assess CT and K during ground running.

  16. Assessing Stride Variables and Vertical Stiffness with GPS-Embedded Accelerometers: Preliminary Insights for the Monitoring of Neuromuscular Fatigue on the Field.

    Science.gov (United States)

    Buchheit, Martin; Gray, Andrew; Morin, Jean-Benoit

    2015-12-01

    The aim of the present study was to examine the ability of a GPS-imbedded accelerometer to assess stride variables and vertical stiffness (K), which are directly related to neuromuscular fatigue during field-based high-intensity runs. The ability to detect stride imbalances was also examined. A team sport player performed a series of 30-s runs on an instrumented treadmill (6 runs at 10, 17 and 24 km·h(-1)) with or without his right ankle taped (aimed at creating a stride imbalance), while wearing on his back a commercially-available GPS unit with an embedded 100-Hz tri-axial accelerometer. Contact (CT) and flying (FT) time, and K were computed from both treadmill and accelerometers (Athletic Data Innovations) data. The agreement between treadmill (criterion measure) and accelerometer-derived data was examined. We also compared the ability of the different systems to detect the stride imbalance. Biases were small (CT and K) and moderate (FT). The typical error of the estimate was trivial (CT), small (K) and moderate (FT), with nearly perfect (CT and K) and large (FT) correlations for treadmill vs. accelerometer. The tape induced very large increase in the right - left foot ∆ in CT, FT and K measured by the treadmill. The tape effect on CT and K ∆ measured with the accelerometers were also very large, but of lower magnitude than with the treadmill. The tape effect on accelerometer-derived ∆ FT was unclear. Present data highlight the potential of a GPS-embedded accelerometer to assess CT and K during ground running. Key pointsGPS-embedded tri-axial accelerometers may be used to assess contact time and vertical stiffness during ground running.These preliminary results open new perspective for the field monitoring of neuromuscular fatigue and performance in run-based sports.

  17. Automated stride assistance device improved the gait parameters and energy cost during walking of healthy middle-aged females but not those of young controls

    Science.gov (United States)

    Otsuki, Risa; Matsumoto, Hiromi; Ueki, Masaru; Uehara, Kazutake; Nozawa, Nobuko; Osaki, Mari; Hagino, Hiroshi

    2016-01-01

    [Purpose] The aim of this study was to clarify the effects of an automated stride assistance device on gait parameters and energy cost during walking performed by healthy middle-aged and young females. [Subjects and Methods] Ten middle-aged females and 10 young females were recruited as case and control participants, respectively. The participants walked for 3 minutes continuously under two different experimental conditions: with the device and without the device. Walking distance, mean walking speed, mean step length, cadence, walk ratio and the physiological cost index during the 3-minutes walk were measured. [Results] When walking with the stride assistance device, the step length and walk ratio of the middle-aged group were significantly higher than without it. Also, during walking without assistance from the device, the physiological cost index of the middle-aged group significantly increased; whereas during walking with assistance, there was no change. The intergroup comparison in the middle-aged group showed the physiological cost index was lower under the experimental condition with assistance provided, as opposed to the condition without the provision of assistance. [Conclusion] The results of this study show that the stride assistance device improved the gait parameters of the middle-aged group but not those of young controls. PMID:28174452

  18. Partial body weight support treadmill training speed influences paretic and non-paretic leg muscle activation, stride characteristics, and ratings of perceived exertion during acute stroke rehabilitation.

    Science.gov (United States)

    Burnfield, Judith M; Buster, Thad W; Goldman, Amy J; Corbridge, Laura M; Harper-Hanigan, Kellee

    2016-06-01

    Intensive task-specific training is promoted as one approach for facilitating neural plastic brain changes and associated motor behavior gains following neurologic injury. Partial body weight support treadmill training (PBWSTT), is one task-specific approach frequently used to improve walking during the acute period of stroke recovery (training parameters and physiologic demands during this early recovery phase. To examine the impact of four walking speeds on stride characteristics, lower extremity muscle demands (both paretic and non-paretic), Borg ratings of perceived exertion (RPE), and blood pressure. A prospective, repeated measures design was used. Ten inpatients post unilateral stroke participated. Following three familiarization sessions, participants engaged in PBWSTT at four predetermined speeds (0.5, 1.0, 1.5 and 2.0mph) while bilateral electromyographic and stride characteristic data were recorded. RPE was evaluated immediately following each trial. Stride length, cadence, and paretic single limb support increased with faster walking speeds (p⩽0.001), while non-paretic single limb support remained nearly constant. Faster walking resulted in greater peak and mean muscle activation in the paretic medial hamstrings, vastus lateralis and medial gastrocnemius, and non-paretic medial gastrocnemius (p⩽0.001). RPE also was greatest at the fastest compared to two slowest speeds (ptraining at the slowest speeds. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. Most suitable mother wavelet for the analysis of fractal properties of stride interval time series via the average wavelet coefficient method.

    Science.gov (United States)

    Zhang, Zhenwei; VanSwearingen, Jessie; Brach, Jennifer S; Perera, Subashan; Sejdić, Ervin

    2017-01-01

    Human gait is a complex interaction of many nonlinear systems and stride intervals exhibiting self-similarity over long time scales that can be modeled as a fractal process. The scaling exponent represents the fractal degree and can be interpreted as a "biomarker" of relative diseases. The previous study showed that the average wavelet method provides the most accurate results to estimate this scaling exponent when applied to stride interval time series. The purpose of this paper is to determine the most suitable mother wavelet for the average wavelet method. This paper presents a comparative numerical analysis of 16 mother wavelets using simulated and real fractal signals. Simulated fractal signals were generated under varying signal lengths and scaling exponents that indicate a range of physiologically conceivable fractal signals. The five candidates were chosen due to their good performance on the mean square error test for both short and long signals. Next, we comparatively analyzed these five mother wavelets for physiologically relevant stride time series lengths. Our analysis showed that the symlet 2 mother wavelet provides a low mean square error and low variance for long time intervals and relatively low errors for short signal lengths. It can be considered as the most suitable mother function without the burden of considering the signal length. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Together We STRIDE: A quasi-experimental trial testing the effectiveness of a multi-level obesity intervention for Hispanic children in rural communities.

    Science.gov (United States)

    Ko, Linda K; Rillamas-Sun, Eileen; Bishop, Sonia; Cisneros, Oralia; Holte, Sarah; Thompson, Beti

    2018-04-01

    Hispanic children are disproportionally overweight and obese compared to their non-Hispanic white counterparts in the US. Community-wide, multi-level interventions have been successful to promote healthier nutrition, increased physical activity (PA), and weight loss. Using community-based participatory approach (CBPR) that engages community members in rural Hispanic communities is a promising way to promote behavior change, and ultimately weight loss among Hispanic children. Led by a community-academic partnership, the Together We STRIDE (Strategizing Together Relevant Interventions for Diet and Exercise) aims to test the effectiveness of a community-wide, multi-level intervention to promote healthier diets, increased PA, and weight loss among Hispanic children. The Together We STRIDE is a parallel quasi-experimental trial with a goal of recruiting 900 children aged 8-12 years nested within two communities (one intervention and one comparison). Children will be recruited from their respective elementary schools. Components of the 2-year multi-level intervention include comic books (individual-level), multi-generational nutrition and PA classes (family-level), teacher-led PA breaks and media literacy education (school-level), family nights, a farmer's market and a community PA event (known as ciclovia) at the community-level. Children from the comparison community will receive two newsletters. Height and weight measures will be collected from children in both communities at three time points (baseline, 6-months, and 18-months). The Together We STRIDE study aims to promote healthier diet and increased PA to produce healthy weight among Hispanic children. The use of CBPR approach and the engagement of the community will springboard strategies for intervention' sustainability. Clinical Trials Registration Number: NCT02982759 Retrospectively registered. Copyright © 2018 Elsevier Inc. All rights reserved.

  1. Socio-demographic psychosocial and clinical characteristics of participants in e-HealthyStrides©: an interactive ehealth program to improve diabetes self-management skills.

    Science.gov (United States)

    Pemu, Priscilla E; Quarshie, Alexander Q; Josiah-Willock, R; Ojutalayo, Folake O; Alema-Mensah, Ernest; Ofili, Elizabeth O

    2011-01-01

    Diabetes self-management (DSM) training helps prevent diabetic complications. eHealth approaches may improve its optimal use. The aims were to determine a) acceptability of e-HealthyStrides© (an interactive, Internet-based, patient-driven, diabetes self-management support and social networking program) among Morehouse Community Physicians' Network diabetics; b) efficacy for DSM behavior change c) success factors for use of e-HealthyStrides©. Baseline characteristics of pilot study participants are reported. Of those approached, 13.8% agreed to participate. Among participants, 96% were Black, 77% female; age 56±9.2 years; education: 44% college or higher and 15% less than 12th grade; 92.5% with home computers. Over half (51%) failed the Diabetes Knowledge Test. Nearly half (47%) were at goal A1C; 24% at goal blood pressure; 3% at goal LDL cholesterol level. Median (SD) Diabetes Empowerment Scale score = 3.93 (0.72) but managing psychosocial aspects = 3.89 (0.89) scored lower than other domains. There was low overall confidence for DSM behaviors. Assistance with healthy eating was the most frequently requested service. Requestors were more obese with worse A1C than others. Chronic care delivery scored average with high scores for counseling and problem solving but low scores for care coordination and follow up.

  2. Research staff training in a multisite randomized clinical trial: Methods and recommendations from the Stimulant Reduction Intervention using Dosed Exercise (STRIDE) trial.

    Science.gov (United States)

    Walker, Robrina; Morris, David W; Greer, Tracy L; Trivedi, Madhukar H

    2014-01-01

    Descriptions of and recommendations for meeting the challenges of training research staff for multisite studies are limited despite the recognized importance of training on trial outcomes. The STRIDE (STimulant Reduction Intervention using Dosed Exercise) study is a multisite randomized clinical trial that was conducted at nine addiction treatment programs across the United States within the National Drug Abuse Treatment Clinical Trials Network (CTN) and evaluated the addition of exercise to addiction treatment as usual (TAU), compared to health education added to TAU, for individuals with stimulant abuse or dependence. Research staff administered a variety of measures that required a range of interviewing, technical, and clinical skills. In order to address the absence of information on how research staff are trained for multisite clinical studies, the current manuscript describes the conceptual process of training and certifying research assistants for STRIDE. Training was conducted using a three-stage process to allow staff sufficient time for distributive learning, practice, and calibration leading up to implementation of this complex study. Training was successfully implemented with staff across nine sites. Staff demonstrated evidence of study and procedural knowledge via quizzes and skill demonstration on six measures requiring certification. Overall, while the majority of staff had little to no experience in the six measures, all research assistants demonstrated ability to correctly and reliably administer the measures throughout the study. Practical recommendations are provided for training research staff and are particularly applicable to the challenges encountered with large, multisite trials.

  3. Improvement in Body Image, Perceived Health, and Health-Related Self-Efficacy Among People With Serious Mental Illness: The STRIDE Study.

    Science.gov (United States)

    Yarborough, Bobbi Jo H; Leo, Michael C; Yarborough, Micah T; Stumbo, Scott; Janoff, Shannon L; Perrin, Nancy A; Green, Carla A

    2016-03-01

    The authors examined secondary outcomes of STRIDE, a randomized controlled trial that tested a weight-loss and lifestyle intervention for individuals taking antipsychotic medications. Hierarchical linear regression was used to explore the effects of the intervention and weight change at follow-up (six, 12, and 24 months) on body image, perceived health, and health-related self-efficacy. Participants were 200 adults who were overweight and taking antipsychotic agents. Weight change × study arm interaction was associated with significant improvement in body image from baseline to six months. From baseline to 12 months, body image scores of intervention participants improved by 1.7 points more compared with scores of control participants; greater weight loss was associated with more improvement. Between baseline and 24 months, greater weight loss was associated with improvements in body image, perceived health, and health-related self-efficacy. Participation in STRIDE improved body image, and losing weight improved perceived health and health-related self-efficacy.

  4. Can Tai Chi training impact fractal stride time dynamics, an index of gait health, in older adults? Cross-sectional and randomized trial studies.

    Directory of Open Access Journals (Sweden)

    Brian J Gow

    Full Text Available To determine if Tai Chi (TC has an impact on long-range correlations and fractal-like scaling in gait stride time dynamics, previously shown to be associated with aging, neurodegenerative disease, and fall risk.Using Detrended Fluctuation Analysis (DFA, this study evaluated the impact of TC mind-body exercise training on stride time dynamics assessed during 10 minute bouts of overground walking. A hybrid study design investigated long-term effects of TC via a cross-sectional comparison of 27 TC experts (24.5 ± 11.8 yrs experience and 60 age- and gender matched TC-naïve older adults (50-70 yrs. Shorter-term effects of TC were assessed by randomly allocating TC-naïve participants to either 6 months of TC training or to a waitlist control. The alpha (α long-range scaling coefficient derived from DFA and gait speed were evaluated as outcomes.Cross-sectional comparisons using confounder adjusted linear models suggest that TC experts exhibited significantly greater long-range scaling of gait stride time dynamics compared with TC-naïve adults. Longitudinal random-slopes with shared baseline models accounting for multiple confounders suggest that the effects of shorter-term TC training on gait dynamics were not statistically significant, but trended in the same direction as longer-term effects although effect sizes were very small. In contrast, gait speed was unaffected in both cross-sectional and longitudinal comparisons.These preliminary findings suggest that fractal-like measures of gait health may be sufficiently precise to capture the positive effects of exercise in the form of Tai Chi, thus warranting further investigation. These results motivate larger and longer-duration trials, in both healthy and health-challenged populations, to further evaluate the potential of Tai Chi to restore age-related declines in gait dynamics.The randomized trial component of this study was registered at ClinicalTrials.gov (NCT01340365.

  5. Strides in Preservation of Malawi's Natural Stone

    Science.gov (United States)

    Kamanga, Tamara; Chisenga, Chikondi; Katonda, Vincent

    2017-04-01

    The geology of Malawi is broadly grouped into four main lithological units that is the Basement Complex, the Karoo Super group, Tertiary to Quaternary sedimentary deposits and the Chilwa Alkaline province. The basement complex rocks cover much of the country and range in age from late Precambrian to early Paleozoic. They have been affected by three major phases of deformation and metamorphism that is the Irumide, Ubendian and The Pan-African. These rocks comprise gneisses, granulites and schists with associated mafic, ultramafic, syenites and granite rocks. The Karoo System sedimentary rocks range in age from Permian to lower Jurassic and are mainly restricted to two areas in the extreme North and extreme Alkaline Province - late Jurassic to Cretaceous in age, preceded by upper Karoo Dolerite dyke swarms and basaltic lavas, have been intruded into the Basement Complex gneisses of southern Malawi. Malawi is endowed with different types of natural stone deposits most of which remain unexploited and explored. Over twenty quarry operators supply quarry stone for road and building construction in Malawi. Hundreds of artisanal workers continue to supply aggregate stones within and on the outskirts of urban areas. Ornamental stones and granitic dimension stones are also quarried, but in insignificant volumes. In Northern Malawi, there are several granite deposits including the Nyika, which is the largest single outcrop occupying approximately 260.5 km2 , Mtwalo Amazonite an opaque to translucent bluish -green variety of microcline feldspar that occurs in alkali granites and pegmatite, the Ilomba granite (sodalite) occurring in small areas within biotite; apatite, plagioclase and calcite. In the Center, there are the Dzalanyama granites, and the Sani granites. In the South, there are the Mangochi granites. Dolerite and gabbroic rocks spread across the country, treading as black granites. Malawi is also endowed with many deposits of marble. A variety of other igneous, metamorphic and sedimentary rocks are also used as dimension stones. Discovery and preservation of more natural stone deposits through research is essential in the country .Natural stone preservation has not only the potential to generate significant direct and indirect economic benefits for Malawi but also to preserve its heritage .

  6. Personalized medicine: Striding from genes to medicines.

    Science.gov (United States)

    Nair, Sunita R

    2010-10-01

    Personalized medicine has the potential of revolutionizing patient care. This treatment modality prescribes therapies specific to individual patients based on pharmacogenetic and pharmacogenomic information. The mapping of the human genome has been an important milestone in understanding the interindividual differences in response to therapy. These differences are attributed to genotypic differences, with consequent phenotypic expression. It is important to note that targeted therapies should ideally be accompanied by a diagnostic marker. However, most efforts are being directed toward developing both these separately; the former by pharmaceutical companies and the later by diagnostic companies. Further, this companion strategy will be successful only when the biomarkers assayed are differentiated on a value-based approach rather than a cost-based approach, especially in countries that reimburse disease management costs. The advantages of using personalized therapies are manifold: targeted patient population; avoidance of drug-related toxicities and optimization of costs in nonresponder patients; reduction in drug development costs, and fewer patients to be tested in clinical trials. The success of personalized therapy in future will depend on a better understanding of pharmacogenomics and the extension of these scientific advances to all countries.

  7. Personalized medicine: Striding from genes to medicines

    OpenAIRE

    Sunita R Nair

    2010-01-01

    Personalized medicine has the potential of revolutionizing patient care. This treatment modality prescribes therapies specific to individual patients based on pharmacogenetic and pharmacogenomic information. The mapping of the human genome has been an important milestone in understanding the interindividual differences in response to therapy. These differences are attributed to genotypic differences, with consequent phenotypic expression. It is important to note that targeted therapies should...

  8. Unravelling Copenhagen's stride into the Anthropocene using lake sediments

    Science.gov (United States)

    Schreiber, Norman; Andersen, Thorbjørn J.; Frei, Robert; Ilsøe, Peter; Louchouarn, Patrick; Andersen, Kenneth; Funder, Svend; Rasmussen, Peter; Andresen, Camilla S.; Odgaard, Bent; Kjær, Kurt H.

    2014-05-01

    Industrialization including the effects of expanding energy consumption and metallurgy production as well as population growth and demographic pressure increased heavy-metal pollution loads progressively since the Industrial Revolution. Especially the burning of fossil fuels mobilizes heavy metals like lead and zinc on a large scale. By wet and dry deposition, these loads end up in the aquatic environment where sediments serve as sinks for these contaminations. In this study, we examine the pollution history of Copenhagen, Denmark. A sediment core was retrieved for the lake in the Botanical Gardens in central Copenhagen using a rod-operated piston corer. The water body used to be part of the old town's defence-wall system and was turned into a lake by terrain levelling in the mid 17th century. After initial X-ray fluorescence core scanning, element concentrations were determined using emission spectroscopy. The onset of gyttja accumulation in the lake is assumed to start immediately after the construction of the fortification in approximately AD 1645. An age model representing the last approximately 135 years for the uppermost 60cm was established by lead-210 and cesium-137 dating. The older part was dated via recognition of markedly increased levels of levoglucosan which are interpreted to be linked with recorded fires in Copenhagen. Similarly, two distinct layers interstratify the sediment column and mark pronounced increases of minerogenic material inflow which can be linked to known historical events. Significant pollution load increases are evident from the 1700s along with urban growth and extended combustion of carbon carriers fuels such as wood and coals. However, a more pronounced increase in lead and zinc deposition only begins by the mid-19th century. Maxima for the latter two pollutants are reached in the late 1970s followed by a reduction of emissions in accordance with stricter environmental regulations. Here, especially the phasing-out of tetraethyl lead from gasoline and increased cleaning of the emissions from local power plants have had an effect. Also a change of fuel from coal to natural gas in the power plants has been very important. The present study shows how a detailed record of past levels of air pollution in large cities may be achieved by analyzing the sediment accumulated in urban lakes provided that a reliable chronology can be established.

  9. The Worker Rights Consortium Makes Strides toward Legitimacy.

    Science.gov (United States)

    Van der Werf, Martin

    2000-01-01

    Discusses the rapid growth of the Workers Rights Consortium, a student-originated group with 44 member institutions which opposes sweatshop labor conditions especially in the apparel industry. Notes disagreements about the number of administrators on the board of directors and about the role of industry representives. Compares this group with the…

  10. Stride length asymmetry in split-belt locomotion

    NARCIS (Netherlands)

    Hoogkamer, W.; Bruijn, S.M.; Duysens, J.

    2013-01-01

    The number of studies utilizing a split-belt treadmill is rapidly increasing in recent years. This has led to some confusion regarding the definitions of reported gait parameters. The purpose of this paper is to clearly present the definitions of the gait parameters that are commonly used in

  11. TAKING MULTI MODE RESEARCH STRIDES DURING THEINNOVATION OF ACRICKETCOMPETITIVE INTELLIGENCEFRAMEWORK

    Directory of Open Access Journals (Sweden)

    Liandi van den Berg

    2017-01-01

    Full Text Available This paperdescribesthemulti-mode research methodological stepsduring thedevelopment of a competitive intelligence (CIframework forcricketcoaches.Currently no framework exist to guide coaches to gain a competitive advantagethrough competitor analysis.Asystematic literature review (SLR ascertainedthesimilarities and differences betweenthebusiness CI and sport coaching andperformance analysis(PAdomains.The qualitative document analysisperformedinATLAS.TITMrendered a reputable inter-and intra-document analysis validitywith #954; =0.79 and 0.78 respectively. Thedocument analysiscontributedtowardsthe compilation ofa semi-structured interview schedule to investigate thebusiness-related CI process occurrence within the sport coaching context. Theinterview schedule was finalised afteruniversity-peers’interviewsprovided inputon the proposed schedule.Thereafter data collection entailedsemi-structuredinterviews with high-level cricket coachesand support staffonCI activities intheir coaching practices.The coach interviews wereverbatimtranscribed andanalysed with ATLAS.TITM.A codebook of the codescreatedin the analysis wascompiled.The researcherestablished the inter-and intra-reliability with a Cohens’Kappa of 0.8. A constant comparative method of data analysisguided theanalysis,whichwas performeduntildata saturationwas reached. The4338interview code incidenceswere quantitized #8210;theconversion of qualitative datatonumerical data.Acoefficient cluster analyses onallindices detectedclusterswitha linkage distanceset at fourwas performed,from which five themes emerged.The71codes were conceptually concatenated into28categories, linked to the fivedifferent themes. The multi-method research design rendered a conceptual andapplicableCIframework for cricket coaches.

  12. Hope and major strides for genetic diseases of the eye

    Indian Academy of Sciences (India)

    2009-12-31

    Dec 31, 2009 ... versible vision loss. This therapeutic model will undoubtedly be used in other retinal disorders. With the current detailed delineation of the clinical mani- festations of genetic eye diseases, and with the availability of precise gene testing, sophisticated retinal imaging and elec- trophysiologic testing modalities ...

  13. Striding Toward Social Justice: The Ecologic Milieu of Physical Activity

    OpenAIRE

    Lee, Rebecca E.; Cubbin, Catherine

    2009-01-01

    Disparities in physical activity should be investigated in light of social justice principles. This manuscript critically evaluates evidence and trends in disparities research within an ecologic framework, focusing on multi-level factors such as neighborhood and racial discrimination that influence physical activity. Discussion focuses on strategies for integrating social justice into physical activity promotion and intervention programming within an ecologic framework.

  14. Feel your stride and find your preferred running speed

    Directory of Open Access Journals (Sweden)

    Thibault Lussiana

    2016-01-01

    Full Text Available There is considerable inter-individual variability in self-selected intensity or running speed. Metabolic cost per distance has been recognized as a determinant of this personal choice. As biomechanical parameters have been connected to metabolic cost, and as different running patterns exist, we can question their possible determinant roles in self-selected speed. We examined the self-selected speed of 15 terrestrial and 16 aerial runners, with comparable characteristics, on a 400 m track and assessed biomechanical parameters and ratings of pleasure/displeasure. The results revealed that aerial runners choose greater speeds associated with shorter contact time, longer flight time, and higher leg stiffness than terrestrial runners. Pleasure was negatively correlated with contact time and positively with leg stiffness in aerial runners and was negatively correlated with flight time in terrestrial runners. We propose the existence of an optimization system allowing the connection of running patterns at running speeds, and feelings of pleasure or displeasure.

  15. Hope and major strides for genetic diseases of the eye

    Indian Academy of Sciences (India)

    2009-12-31

    Dec 31, 2009 ... There have been dramatic advances in the elucidation of the genetic etiology of inherited eye diseases and their underly- ing pathophysiology in the last two to three decades. This was made possible by the exponential development of pow- erful molecular biology instrumentation and techniques, the.

  16. Eradication of campus cultism: a giant stride toward restoration of ...

    African Journals Online (AJOL)

    In view of this, this paper focuses on campus cult and proposed that its eradication will lead to a restoration of confidence in education in Nigeria. The paper started by looking at the meaning of cultism, the history of campus cult, psychological assumptions for joining cult gang, depicting characteristics of cult groups, the ...

  17. Finding Our Stride: Young Women Professors of Educational Leadership

    Science.gov (United States)

    Hewcomb, Whitney Sherman; Beaty, Danna M.; Sanzo, Karen; Peters-Hawkins, April

    2013-01-01

    This work is grounded in the literature on women in the academy and offers glimpses into four young women professors' experiences in the field of educational leadership. We utilized reflective practice and interpersonal communication to create a dialogue centered on three qualitative research questions that allows a window into our lives. We…

  18. Replacement of a vessel head, an operation which today gets easily into its stride

    International Nuclear Information System (INIS)

    Mardon, P.; Chaumont, J.C.; Lambiotte, P.

    1995-01-01

    In 1992, one year after the detection of a leak in a vessel head of the Electricite de France (EDF) Bugey 4 reactor, the head was replaced by the Framatome-Jeumont Industrie Group. Today, this group, which has developed new methods and new tools to optimize the cost, the time-delay and the dosimetry of this kind of intervention, has performed 11 additional replacements, two of which on 1300 MWe power units. This paper describes step by step the successive operations required for a complete vessel head replacement, including the testing of safety systems before starting up the reactor. (J.S.). 7 photos

  19. Concussion Assessment in California Community College Football: Athletic Trainers' Strides toward a Safer Return to Play

    Science.gov (United States)

    Chinn, Nancy Resendes

    2010-01-01

    The purpose of this mixed method study was to compare current practices of athletic trainers in the management of concussion in football at California Community Colleges (CCC) with the concussion management guidelines set forth by the National Athletic Trainers Association (NATA). The study also set out to gain understanding of why some athletic…

  20. Striding networks of inter-process communication based on TCP/IP protocol

    International Nuclear Information System (INIS)

    Lou Yi; Chen Haichun; Qian Jing; Chen Zhuomin

    2004-01-01

    A mode of process/thread communication between QNX and WINDOWS operating systems in isomerous computers is described. It is proved in practice to be an entirely feasible mode with high efficiency and reliability. A socket created by Socket API is used to communicate between two operating systems. (authors)

  1. Moving Along: In biomechanics, rehabilitation engineering, and movement analysis, Italian researchers are making great strides.

    Science.gov (United States)

    Gugliellmelli, Eugenio; Micera, Silvestro; Migliavacca, Francesco; Pedotti, Antonio

    2015-01-01

    In Italy, biomechanics research and the analysis of human and animal movement have had a very long history, beginning with the exceptional pioneering work of Leonardo da Vinci. In 1489, da Vinci began investigating human anatomy, including an examination of human tendons, muscles, and the skeletal system. He continued this line of inquiry later in life, identifying what he called "the four powers--movement, weight, force, and percussion"--and how he thought they worked in the human body. His approach, by the way, was very modern--analyzing nature through anatomy, developing models for interpretation, and transferring this knowledge to bio-inspired machines.

  2. OneSAF as an In-Stride Mission Command Asset

    Science.gov (United States)

    2014-06-01

    behaviors. These behaviors can be fully automated through additional software development or by chaining existing behaviors. This remains a gap...additional software development or by chaining existing behaviors. This remains a gap area as there has been relatively little effort to create...Stimulation,” OneSAF Co- Developer Technical Exchange Meeting 2012, Sep 2012. [5] M. McCall , B. Murray: “IEEE 1278 Distributed Interactive Simulation

  3. Identification of Biomolecular Building Blocks by Recognition Tunneling: Stride towards Nanopore Sequencing of Biomolecules

    Science.gov (United States)

    Sen, Suman

    DNA, RNA and Protein are three pivotal biomolecules in human and other organisms, playing decisive roles in functionality, appearance, diseases development and other physiological phenomena. Hence, sequencing of these biomolecules acquires the prime interest in the scientific community. Single molecular identification of their building blocks can be done by a technique called Recognition Tunneling (RT) based on Scanning Tunneling Microscope (STM). A single layer of specially designed recognition molecule is attached to the STM electrodes, which trap the targeted molecules (DNA nucleoside monophosphates, RNA nucleoside monophosphates or amino acids) inside the STM nanogap. Depending on their different binding interactions with the recognition molecules, the analyte molecules generate stochastic signal trains accommodating their "electronic fingerprints". Signal features are used to detect the molecules using a machine learning algorithm and different molecules can be identified with significantly high accuracy. This, in turn, paves the way for rapid, economical nanopore sequencing platform, overcoming the drawbacks of Next Generation Sequencing (NGS) techniques. To read DNA nucleotides with high accuracy in an STM tunnel junction a series of nitrogen-based heterocycles were designed and examined to check their capabilities to interact with naturally occurring DNA nucleotides by hydrogen bonding in the tunnel junction. These recognition molecules are Benzimidazole, Imidazole, Triazole and Pyrrole. Benzimidazole proved to be best among them showing DNA nucleotide classification accuracy close to 99%. Also, Imidazole reader can read an abasic monophosphate (AP), a product from depurination or depyrimidination that occurs 10,000 times per human cell per day. In another study, I have investigated a new universal reader, 1-(2-mercaptoethyl)pyrene (Pyrene reader) based on stacking interactions, which should be more specific to the canonical DNA nucleosides. In addition, Pyrene reader showed higher DNA base-calling accuracy compare to Imidazole reader, the workhorse in our previous projects. In my other projects, various amino acids and RNA nucleoside monophosphates were also classified with significantly high accuracy using RT. Twenty naturally occurring amino acids and various RNA nucleosides (four canonical and two modified) were successfully identified. Thus, we envision nanopore sequencing biomolecules using Recognition Tunneling (RT) that should provide comprehensive betterment over current technologies in terms of time, chemical and instrumental cost and capability of de novo sequencing.

  4. 78 FR 61358 - Mylan, Inc., Agila Specialties Global Pte. Limited, Agila Specialties Private Limited and Strides...

    Science.gov (United States)

    2013-10-03

    ... for making sure that your comment does not include any sensitive personal information, like anyone's....10(a)(2). In particular, do not include competitively sensitive information such as costs, sales... compete in those markets in the future, and that competition is expected to reduce prices for consumers...

  5. Elemental characterization of marijuana (cannabis sativa) as a stride in the isolation of its active ingredients

    International Nuclear Information System (INIS)

    Ahmed, Y.A.; Jaoji, A.A.; Olalekan, Y.S.

    2010-01-01

    Seed, stem and leaves samples of Marijuana (Cannabis sativa) popularly called Indian Hemp available in northern Nigeria were analyzed for trace amounts of Mg, Al, Ca, Ti, Mn, Na, Br, La, Yb, Cr, Fe, Zn, and Ba using Instrumental Neutron Activation Analysis. Sample sizes of roughly 300mg irradiated for five minutes (short irradiation) and six hours (long irradiation), with decay times of 7 minutes, 10,000 minutes and 26,000 minutes for short, medium and long-lived nuclides respectively. Counting times for ten minutes (short-lived nuclides), 1,800 minutes (medium-lived nuclides) and 36,000 minutes (long-lived nuclides) yielded detection limits between 0.05 - 0.09μg/g. For comparative study, refined tobacco produced by a tobacco company operating in northern Nigeria were characterized together with the marijuana-which is usually smoked raw with leaves stem and seed packed together. The results obtained shows that both the refined tobacco and the raw marijuana have high c oncentration of Ca, Mg, Al and Mn and low values of Na, Br and La. However, marijuana was found to have heavy elements in abundance compared to the refined tobacco, with Zn = 20.5 μg/g and Cr = 14.3μg/g recording the highest values among the heavy elements detected. This is a sharp difference between the two since the values of heavy elements obtained for the refined tobacco are even below detection limits. Quality Control and Quality Assurance was tested using certified reference material obtained from NIST (Tomato Leaves).

  6. Current strides in AAV-derived vectors and SIN channels further ...

    African Journals Online (AJOL)

    A.S. Odiba

    Vectors used in Gene Therapy Clinical Trials. Data Sourced from: The Journal of Gene. Medicine (www.wiley.co.uk/genmed/clinical) on 2nd June 2017. Vector. Gene Therapy. Clinical Trials. Number. %. Alphavirus (VEE) Replicon Vaccine. 1. 0. E. coli. 2. 0.1. Bifidobacterium longum. 1. 0. CRISPR-Cas9. 7. 0.3. Adenovirus + ...

  7. Striding Out With Parkinson Disease: Evidence-Based Physical Therapy for Gait Disorders

    Science.gov (United States)

    Martin, Clarissa L.; Schenkman, Margaret L.

    2010-01-01

    Although Parkinson disease (PD) is common throughout the world, the evidence for physical therapy interventions that enable long-term improvement in walking is still emerging. This article critiques the major physical therapy approaches related to gait rehabilitation in people with PD: compensatory strategies, motor skill learning, management of secondary sequelae, and education to optimize physical activity and reduce falls. The emphasis of this review is on gait specifically, although balance and falls are of direct importance to gait and are addressed in that context. Although the researchers who have provided the evidence for these approaches grounded their studies on different theoretical paradigms, each approach is argued to have a valid place in the comprehensive management of PD generally and of gait in particular. The optimal mix of interventions for each individual varies according to the stage of disease progression and the patient's preferred form of exercise, capacity for learning, and age. PMID:20022998

  8. Sun Grant Initiative : great strides toward a sustainable and more energy-independent future

    Science.gov (United States)

    2014-09-01

    The Sun Grant Initiative publication, developed by the U.S. Department of Transportation, offers a glimpse of how the Sun Grant Initiative Centers are advancing alternative fuels research. Transportation plays a significant role in biofuels research,...

  9. Marine microbiology: A glimpse of the strides in the Indian and the global arena

    Digital Repository Service at National Institute of Oceanography (India)

    LokaBharathi, P.A.; Nair, S.; Chandramohan, D.

    to understand the form and function of bacteria that are responsible for mediating the various processes in the sea. The field evolves from culture based ecology to direct quantification of these in different marine niches. Insights into some...

  10. China academics feel a sting scientists fear crackdown jeopardized research strides

    CERN Document Server

    Sanger, David E

    1989-01-01

    An international conference on HTS in China a failure after western speakers boycott the event and Chinese speakers forced to study speeches of the Chinese government leader instead of preparing papers (1 page).

  11. Striding out with Parkinson disease: evidence-based physical therapy for gait disorders.

    Science.gov (United States)

    Morris, Meg E; Martin, Clarissa L; Schenkman, Margaret L

    2010-02-01

    Although Parkinson disease (PD) is common throughout the world, the evidence for physical therapy interventions that enable long-term improvement in walking is still emerging. This article critiques the major physical therapy approaches related to gait rehabilitation in people with PD: compensatory strategies, motor skill learning, management of secondary sequelae, and education to optimize physical activity and reduce falls. The emphasis of this review is on gait specifically, although balance and falls are of direct importance to gait and are addressed in that context. Although the researchers who have provided the evidence for these approaches grounded their studies on different theoretical paradigms, each approach is argued to have a valid place in the comprehensive management of PD generally and of gait in particular. The optimal mix of interventions for each individual varies according to the stage of disease progression and the patient's preferred form of exercise, capacity for learning, and age.

  12. Low-frequency sonophoresis: current status and future prospects.

    Science.gov (United States)

    Ogura, Makoto; Paliwal, Sumit; Mitragotri, Samir

    2008-06-30

    Application of ultrasound enhances skin permeability to drugs, a phenomenon referred to as sonophoresis. Significant strides have been made in sonophoresis research in recent years, especially under low-frequency conditions (20 kHzsonophoresis under low-frequency conditions. Several therapeutic macromolecules including insulin, low-molecular weight heparin, and vaccines have been delivered using low-frequency sonophoresis in vivo. Clinical trials have been performed with several drugs including lidocaine and cyclosporin. Novel theoretical and experimental approaches have provided insights into the mechanisms of low-frequency sonophoresis. Current understanding of these mechanisms is presented.

  13. Government leadership in addressing public health priorities: strides and delays in electronic laboratory reporting in the United States.

    Science.gov (United States)

    Gluskin, Rebecca Tave; Mavinkurve, Maushumi; Varma, Jay K

    2014-03-01

    For nearly a decade, interest groups, from politicians to economists to physicians, have touted digitization of the nation's health information. One frequently mentioned benefit is the transmission of information electronically from laboratories to public health personnel, allowing them to rapidly analyze and act on these data. Switching from paper to electronic laboratory reports (ELRs) was thought to solve many public health surveillance issues, including workload, accuracy, and timeliness. However, barriers remain for both laboratories and public health agencies to realize the full benefits of ELRs. The New York City experience highlights several successes and challenges of electronic reporting and is supported by peer-reviewed literature. Lessons learned from ELR systems will benefit efforts to standardize electronic medical records reporting to health departments.

  14. Visuomotor Entrainment and the Frequency-Dependent Response of Walking Balance to Perturbations.

    Science.gov (United States)

    Franz, Jason R; Francis, Carrie; Allen, Matt; Thelen, Darryl G

    2016-08-26

    Visuomotor entrainment, or the synchronization of motor responses to visual stimuli, is a naturally emergent phenomenon in human standing. Our purpose was to investigate the prevalence and resolution of visuomotor entrainment in walking and the frequency-dependent response of walking balance to perturbations. We used a virtual reality environment to manipulate optical flow in ten healthy young adults during treadmill walking. A motion capture system recorded trunk, sacrum, and heel marker trajectories during a series of 3-min conditions in which we perturbed a virtual hallway mediolaterally with systematic changes in the driving frequencies of perceived motion. We quantified visuomotor entrainment using spectral analyses and balance deficits using trunk sway, gait variability, and detrended fluctuation analyses (DFA). ML kinematics were highly sensitive to visual perturbations, and instinctively synchronized (i.e., entrained) to a broad range of driving frequencies of perceived ML motion. However, the influence of visual perturbations on metrics of walking balance was frequency-dependent and governed by their proximity to stride frequency. Specifically, we found that a driving frequency nearest to subjects' average stride frequency uniquely compromised trunk sway, gait variability, and step-to-step correlations. We conclude that visuomotor entrainment is a robust and naturally emerging phenomenon during human walking, involving coordinated and frequency-dependent adjustments in trunk sway and foot placement to maintain balance at the whole-body level. These findings provide mechanistic insight into how the visuomotor control of walking balance is disrupted by visual perturbations and important reference values for the emergence of balance deficits due to age, injury, or disease.

  15. Vertical and lateral horizontal forces of walking area running pedestrians

    Czech Academy of Sciences Publication Activity Database

    Urushadze, Shota; Pirner, Miroš

    2016-01-01

    Roč. 2, č. 1 (2016), s. 38-50 ISSN 2149-8024 R&D Projects: GA ČR(CZ) GA15-01035S Institutional support: RVO:68378297 Keywords : stride strength * stride frequency * step frequency * dynamic coefficient * effects of striding velocity Subject RIV: JM - Building Engineering http://www.challengejournal.com/index.php/cjsmec/article/view/54

  16. Displacement of the pelvis during human walking : experimental data and model predictions

    NARCIS (Netherlands)

    Zijlstra, W; Hof, AL

    1997-01-01

    Displacements of the pelvis during treadmill walking were studied in dependence of walking speed, stride frequency and stride length. Displacement curves per stride cycle were described by means of harmonic analysis. Simple mechanical, or geometrical models of the body's center of mass (COM)

  17. Making strides in women’s mental health care delivery in rural Ethiopia: demographics of a female outpatient psychiatric cohort at Jimma University Specialized Hospital (2006–2008

    Directory of Open Access Journals (Sweden)

    Chemali ZN

    2013-07-01

    Full Text Available Zeina N Chemali,1,2 Christina PC Borba,1,2 Tanya E Henderson,3 Markos Tesfaye41Department of Psychiatry, Massachusetts General Hospital, Boston, MA, USA; 2Harvard Medical School, Boston, MA, USA; 3International and Human Rights Law Consultants, Cambridge, MA, USA; 4Department of Psychiatry, College of Public Health and Medical Sciences, Jimma University, Jimma, EthiopiaAbstract: This paper presents the delivery of mental health care to a sample of women living in Jimma, rural Ethiopia, and their access to mental health services. A total of 226 psychiatric charts were reviewed for women seen at Jimma University Specialized Hospital. The mental health charts included documentation ranging from one paragraph to a full note. No psychiatric chart recorded medication status, detailed substance abuse history, or a history of violence. Rendering appropriate mental health care for women requires concerted efforts by multiple stake holders. Using our results, we advance concrete and practical suggestions for improving women's mental health in rural Ethiopia. We point out that the health care system needs to be responsive, allowing for change starting with gender rights, so that rural women have access to basic mental health services.Keywords: global mental health, low income country, Africa, gender differences

  18. Maximum swimming speeds of sailfish and three other large marine predatory fish species based on muscle contraction time and stride length: a myth revisited

    Directory of Open Access Journals (Sweden)

    Morten B. S. Svendsen

    2016-10-01

    Full Text Available Billfishes are considered to be among the fastest swimmers in the oceans. Previous studies have estimated maximum speed of sailfish and black marlin at around 35 m s−1 but theoretical work on cavitation predicts that such extreme speed is unlikely. Here we investigated maximum speed of sailfish, and three other large marine pelagic predatory fish species, by measuring the twitch contraction time of anaerobic swimming muscle. The highest estimated maximum swimming speeds were found in sailfish (8.3±1.4 m s−1, followed by barracuda (6.2±1.0 m s−1, little tunny (5.6±0.2 m s−1 and dorado (4.0±0.9 m s−1; although size-corrected performance was highest in little tunny and lowest in sailfish. Contrary to previously reported estimates, our results suggest that sailfish are incapable of exceeding swimming speeds of 10-15 m s−1, which corresponds to the speed at which cavitation is predicted to occur, with destructive consequences for fin tissues.

  19. Middle-Out Approaches to Reform of University Teaching and Learning: Champions striding between the top-down and bottom-up approaches

    Directory of Open Access Journals (Sweden)

    Rick Cummings

    2005-03-01

    Full Text Available In recent years, Australian universities have been driven by a diversity of external forces, including funding cuts, massification of higher education, and changing student demographics, to reform their relationship with students and improve teaching and learning, particularly for those studying off-campus or part-time. Many universities have responded to these forces either through formal strategic plans developed top-down by executive staff or through organic developments arising from staff in a bottom-up approach. By contrast, much of Murdoch University’s response has been led by a small number of staff who have middle management responsibilities and who have championed the reform of key university functions, largely in spite of current policy or accepted practice. This paper argues that the ‘middle-out’ strategy has both a basis in change management theory and practice, and a number of strengths, including low risk, low cost, and high sustainability. Three linked examples of middle-out change management in teaching and learning at Murdoch University are described and the outcomes analyzed to demonstrate the benefits and pitfalls of this approach.

  20. Maximum swimming speeds of sailfish and three other large marine predatory fish species based on muscle contraction time and stride length

    DEFF Research Database (Denmark)

    Svendsen, Morten Bo Søndergaard; Domenici, Paolo; Marras, Stefano

    2016-01-01

    Billfishes are considered to be among the fastest swimmers in the oceans. Previous studies have estimated maximum speed of sailfish and black marlin at around 35 m s(-1) but theoretical work on cavitation predicts that such extreme speed is unlikely. Here we investigated maximum speed of sailfish......, and three other large marine pelagic predatory fish species, by measuring the twitch contraction time of anaerobic swimming muscle. The highest estimated maximum swimming speeds were found in sailfish (8.3±1.4 m s(-1)), followed by barracuda (6.2±1.0 m s(-1)), little tunny (5.6±0.2 m s(-1)) and dorado (4...

  1. Stride lengths, speed and energy costs in walking of Australopithecus afarensis: using evolutionary robotics to predict locomotion of early human ancestors

    OpenAIRE

    Sellers, William I; Cain, Gemma M; Wang, Weijie; Crompton, Robin H

    2005-01-01

    This paper uses techniques from evolutionary robotics to predict the most energy-efficient upright walking gait for the early human relative Australopithecus afarensis, based on the proportions of the 3.2 million year old AL 288-1 ‘Lucy’ skeleton, and matches predictions against the nearly contemporaneous (3.5–3.6 million year old) Laetoli fossil footprint trails. The technique creates gaits de novo and uses genetic algorithm optimization to search for the most efficient patterns of simulated...

  2. Developing an Adaptive Robotic Assistant for Close-Proximity Human-Robot Interaction in Space Environments

    Data.gov (United States)

    National Aeronautics and Space Administration — As mankind continues making strides in space exploration and associated technologies, the frequency, duration, and complexity of human space exploration missions...

  3. Deactivation rate and shortening velocity as determinants of contractile frequency.

    Science.gov (United States)

    Marsh, R L

    1990-08-01

    The kinetic properties of muscle that could influence locomotor frequency include rate of activation, rate of cross-bridge "attachment", intrinsic shortening velocity, and rate of deactivation. The latter two mechanisms are examined using examples from high-speed running in lizards and escape swimming in scallops. During running, inertial loading and elastic energy storage probably mitigate the effects of thermal alterations in intrinsic muscle shortening velocity. The result is a rather low thermal dependence of stride frequency over a 15-20 degree C temperature range. However, at lower temperatures, the longer times required for deactivation cause the thermal dependence of frequency to increase greatly. Scallops use a single muscle to swim by jet propulsion. In vivo shortening velocity in these animals also shows a low thermal dependence. As with high-speed running, the mechanics of jet propulsion may limit the effects of thermally induced changes in intrinsic shortening velocity. The largest thermal effect during swimming is on the initial phase of valve opening. The effects of temperature on the rate of deactivation of the adductor muscle could play an important role in limiting reextension of the muscle, which is dependent on elastic energy storage in the hinge ligament. These examples illustrate that the relative importance of various intrinsic contractile properties in controlling locomotor performance depends on the mechanics of the movements.

  4. The U.K. Pushes the Boundaries of Bionics: Researchers and Engineers Are Making Great Strides Toward Advanced Prosthetics' Ultimate Goal-Mimicking the Functionality of a Real Limb.

    Science.gov (United States)

    Banks, Jim

    2016-01-01

    Using state-of-the-art technology, athletes at the Paralympic Games achieve great feats of physical prowess, but for most people using assistive and rehabilitative technologies (ART), even simple tasks can present huge challenges. Many do not make full use of the technology available to them because it is unreliable, uncomfortable, and nonintuitive, so researchers are pushing the envelope to create practical solutions that function like real limbs.

  5. Early Detection of Amyotrophic Lateral Sclerosis (ALS using the Gait Motor Signal Frequency Analysis

    Directory of Open Access Journals (Sweden)

    Behzad Abedi

    2016-06-01

    Full Text Available Abstract Background: ALS is a progressive neuro-muscular disease, which is characterized by motor neuron loss in the Central Nervous System (CNS and Peripheral Nervous System (PNS. Up to now, no accurate clinical method for diagnosis of the disease have been provided. In most cases, ALS patients are unable to walk normally due to abnormalities in the nervous system. For this reason, one of the most appropriate methods in the diagnosis of ALS from other neurological diseases or from healthy volunteers is the gait motor signal analysis. Materials and Methods: In this study, gait signals available in Physionet database have been used. The database consists of 13 patients with ALS (ALS1, ALS2, …, ALS13 and 16 normal subjects (CO1, CO2, …, CO16. The patients participating in this study had no history of any psychiatric disorders and did not use any assistive device for walking, like wheelchair. The power spectrum of stride, swing, and stance of normal subjects and patients was computed for both left and right legs. To provide appropriate inputs for the classifier, the frequency band of the power spectrum of all signals was divided into eight equal parts. The area of all regions was computed. Three frequency band of the lower range of power spectra selected as inputs of the classifier. Results: In this study, power spectra, as frequency attributes, were used to explore probable differences of time series in both patients and healthy subjects. Conclusion: Artificial Neural Network was used to classify normal and ALS groups with the accuracy of 83% for the test data set. It seems that the present algorithm can be used in discriminating patients from normal subjects in the early stages of the disease.

  6. Predicting Statistical Distributions of Footbridge Vibrations

    DEFF Research Database (Denmark)

    Pedersen, Lars; Frier, Christian

    2009-01-01

    The paper considers vibration response of footbridges to pedestrian loading. Employing Newmark and Monte Carlo simulation methods, a statistical distribution of bridge vibration levels is calculated modelling walking parameters such as step frequency and stride length as random variables...

  7. Walking on an Oscillating Treadmill: Two Paths to Functional Adaptation

    Science.gov (United States)

    Brady, Rachel A.; Peters, Brian T.; Bloomberg, Jacob J.

    2010-01-01

    We mounted a treadmill on top of a six degree-of-freedom motion base platform to investigate and characterize locomotor responses produced by healthy adults when introduced to a novel walking condition. Subjects were classified into two groups according to how their stride times were affected by the perturbation. Our data suggest that a person's choice of adaptation strategy is influenced by the relationship between his unique, natural stride frequency and the external frequency imposed by the motion base. Our data suggest that a person's stride time response while walking on a laterally oscillating treadmill is influenced by the relationship between his unique, natural stride frequency and the imposed external frequency of the motion base. This relationship may be useful for checking the efficacy of gait training and rehabilitation programs. Preselecting and manipulating a person's EST could be one way to draw him out of his preferred "entrainment well" during therapy or training.

  8. Gait disorders in the elderly and dual task gait analysis: a new approach for identifying motor phenotypes.

    Science.gov (United States)

    Auvinet, Bernard; Touzard, Claude; Montestruc, François; Delafond, Arnaud; Goeb, Vincent

    2017-01-31

    Gait disorders and gait analysis under single and dual-task conditions are topics of great interest, but very few studies have looked for the relevance of gait analysis under dual-task conditions in elderly people on the basis of a clinical approach. An observational study including 103 patients (mean age 76.3 ± 7.2, women 56%) suffering from gait disorders or memory impairment was conducted. Gait analysis under dual-task conditions was carried out for all patients. Brain MRI was performed in the absence of contra-indications. Three main gait variables were measured: walking speed, stride frequency, and stride regularity. For each gait variable, the dual task cost was computed and a quartile analysis was obtained. Nonparametric tests were used for all the comparisons (Wilcoxon, Kruskal-Wallis, Fisher or Chi 2 tests). Four clinical subgroups were identified: gait instability (45%), recurrent falls (29%), memory impairment (18%), and cautious gait (8%). The biomechanical severity of these subgroups was ordered according to walking speed and stride regularity under both conditions, from least to most serious as follows: memory impairment, gait instability, recurrent falls, cautious gait (p gait disorders, 5 main pathological subgroups were identified (musculoskeletal diseases (n = 11), vestibular diseases (n = 6), mild cognitive impairment (n = 24), central nervous system pathologies, (n = 51), and without diagnosis (n = 8)). The dual task cost for walking speed, stride frequency and stride regularity were different among these subgroups (p analysis of dual task cost for stride frequency and stride regularity allowed the identification of 3 motor phenotypes (p Gait analysis under dual-task conditions in elderly people suffering from gait disorders or memory impairment is of great value in assessing the severity of gait disorders, differentiating between peripheral pathologies and central nervous system pathologies, and identifying motor

  9. Inducing self-selected human engagement in robotic locomotion training.

    Science.gov (United States)

    Collins, Steven H; Jackson, Rachel W

    2013-06-01

    Stroke leads to severe mobility impairments for millions of individuals each year. Functional outcomes can be improved through manual treadmill therapy, but high costs limit patient exposure and, thereby, outcomes. Robotic gait training could increase the viable duration and frequency of training sessions, but robotic approaches employed thus far have been less effective than manual therapy. These shortcomings may relate to subconscious energy-minimizing drives, which might cause patients to engage less actively in therapy when provided with corrective robotic assistance. We have devised a new method for gait rehabilitation that harnesses, rather than fights, least-effort tendencies. Therapeutic goals, such as increased use of the paretic limb, are made easier than the patient's nominal gait through selective assistance from a robotic platform. We performed a pilot test on a healthy subject (N = 1) in which altered self-selected stride length was induced using a tethered robotic ankle-foot orthosis. The subject first walked on a treadmill while wearing the orthosis with and without assistance at unaltered and voluntarily altered stride length. Voluntarily increasing stride length by 5% increased metabolic energy cost by 4%. Robotic assistance decreased energy cost at both unaltered and voluntarily increased stride lengths, by 6% and 8% respectively. We then performed a test in which the robotic system continually monitored stride length and provided more assistance if the subject's stride length approached a target increase. This adaptive assistance protocol caused the subject to slowly adjust their gait patterns towards the target, leading to a 4% increase in stride length. Metabolic energy consumption was simultaneously reduced by 5%. These results suggest that selective-assistance protocols based on targets relevant to rehabilitation might lead patients to self-select desirable gait patterns during robotic gait training sessions, possibly facilitating better

  10. Surface-EMG analysis for the quantification of thigh muscle dynamic co-contractions during normal gait.

    Science.gov (United States)

    Strazza, Annachiara; Mengarelli, Alessandro; Fioretti, Sandro; Burattini, Laura; Agostini, Valentina; Knaflitz, Marco; Di Nardo, Francesco

    2017-01-01

    The research purpose was to quantify the co-contraction patterns of quadriceps femoris (QF) vs. hamstring muscles during free walking, in terms of onset-offset muscular activation, excitation intensity, and occurrence frequency. Statistical gait analysis was performed on surface-EMG signals from vastus lateralis (VL), rectus femoris (RF), and medial hamstrings (MH), in 16315 strides walked by 30 healthy young adults. Results showed full superimpositions of MH with both VL and RF activity from terminal swing, 80 to 100% of gait cycle (GC), to the successive loading response (≈0-15% of GC), in around 90% of the considered strides. A further superimposition was detected during the push-off phase both between VL and MH activation intervals (38.6±12.8% to 44.1±9.6% of GC) in 21.9±13.6% of strides, and between RF and MH activation intervals (45.9±5.3% to 50.7±9.7 of GC) in 32.7±15.1% of strides. These findings led to identify three different co-contractions among QF and hamstring muscles during able-bodied walking: in early stance (in ≈90% of strides), in push-off (in 25-30% of strides) and in terminal swing (in ≈90% of strides). The co-contraction in terminal swing is the one with the highest levels of muscle excitation intensity. To our knowledge, this analysis represents the first attempt for quantification of QF/hamstring muscles co-contraction in young healthy subjects during normal gait, able to include the physiological variability of the phenomenon. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. How to Sync to the Beat of a Persistent Fractal Metronome without Falling Off the Treadmill?

    Directory of Open Access Journals (Sweden)

    Melvyn Roerdink

    Full Text Available In rehabilitation, rhythmic acoustic cues are often used to improve gait. However, stride-time fluctuations become anti-persistent with such pacing, thereby deviating from the characteristic persistent long-range correlations in stride times of self-paced walking healthy adults. Recent studies therefore experimented with metronomes with persistence in interbeat intervals and successfully evoked persistent stride-time fluctuations. The objective of this study was to examine how participants couple their gait to a persistent metronome, evoking persistently longer or shorter stride times over multiple consecutive strides, without wandering off the treadmill. Twelve healthy participants walked on a treadmill in self-paced, isochronously paced and non-isochronously paced conditions, the latter with anti-persistent, uncorrelated and persistent correlations in interbeat intervals. Stride-to-stride fluctuations of stride times, stride lengths and stride speeds were assessed with detrended fluctuation analysis, in conjunction with an examination of the coupling between stride times and stride lengths. Stride-speed fluctuations were anti-persistent for all conditions. Stride-time and stride-length fluctuations were persistent for self-paced walking and anti-persistent for isochronous pacing. Both stride times and stride lengths changed from anti-persistence to persistence over the four non-isochronous metronome conditions, accompanied by an increasingly stronger coupling between these gait parameters, with peak values for the persistent metronomes. These results revealed that participants were able to follow the beat of a persistent metronome without falling off the treadmill by strongly coupling stride-length fluctuations to the stride-time fluctuations elicited by persistent metronomes, so as to prevent large positional displacements along the treadmill. For self-paced walking, in contrast, this coupling was very weak. In combination, these results

  12. Energy Expenditure of Trotting Gait Under Different Gait Parameters

    Science.gov (United States)

    Chen, Xian-Bao; Gao, Feng

    2017-07-01

    Robots driven by batteries are clean, quiet, and can work indoors or in space. However, the battery endurance is a great problem. A new gait parameter design energy saving strategy to extend the working hours of the quadruped robot is proposed. A dynamic model of the robot is established to estimate and analyze the energy expenditures during trotting. Given a trotting speed, optimal stride frequency and stride length can minimize the energy expenditure. However, the relationship between the speed and the optimal gait parameters is nonlinear, which is difficult for practical application. Therefore, a simplified gait parameter design method for energy saving is proposed. A critical trotting speed of the quadruped robot is found and can be used to decide the gait parameters. When the robot is travelling lower than this speed, it is better to keep a constant stride length and change the cycle period. When the robot is travelling higher than this speed, it is better to keep a constant cycle period and change the stride length. Simulations and experiments on the quadruped robot show that by using the proposed gait parameter design approach, the energy expenditure can be reduced by about 54% compared with the 100 mm stride length under 500 mm/s speed. In general, an energy expenditure model based on the gait parameter of the quadruped robot is built and the trotting gait parameters design approach for energy saving is proposed.

  13. Airway Clearance Techniques (ACTs)

    Medline Plus

    Full Text Available ... a Participant CF Climb CF Cycle for Life Great Strides Xtreme Hike Participate In addition to working ... FIND A CLINICAL TRIAL FIND A LOCAL CHAPTER Great Strides Participate in an Event Conference Livestreams Fundraising ...

  14. Demonstrate a Low Biochemical Oxygen Demand Aircraft Deicing Fluid

    Science.gov (United States)

    2013-03-04

    operations of the aircraft Observations collected from flight crew Flight control response, visibility, thrust (drag) and refueling boom...individual’s hip is centered between the two feet when the front foot first impacts, the stride length can be easily calculated (Figure 5). Stride...Length (LS) ≈ 2 x (h x sinΘ) Where: h = hip height Θ = angle of impact Stride Length Approximation Hip Foot Stride Length Angle of Impact 8 In

  15. Theoretical considerations on maximum running speeds for large and small animals.

    Science.gov (United States)

    Fuentes, Mauricio A

    2016-02-07

    Mechanical equations for fast running speeds are presented and analyzed. One of the equations and its associated model predict that animals tend to experience larger mechanical stresses in their limbs (muscles, tendons and bones) as a result of larger stride lengths, suggesting a structural restriction entailing the existence of an absolute maximum possible stride length. The consequence for big animals is that an increasingly larger body mass implies decreasing maximal speeds, given that the stride frequency generally decreases for increasingly larger animals. Another restriction, acting on small animals, is discussed only in preliminary terms, but it seems safe to assume from previous studies that for a given range of body masses of small animals, those which are bigger are faster. The difference between speed scaling trends for large and small animals implies the existence of a range of intermediate body masses corresponding to the fastest animals. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Pedestrian Dynamics - Footbridge Loads

    Czech Academy of Sciences Publication Activity Database

    Pirner, Miroš; Urushadze, Shota

    52 2007, č. 3 (2007), s. 269-283 ISSN 0001-7043 R&D Projects: GA ČR(CZ) GA103/05/2066 Institutional research plan: CEZ:AV0Z20710524 Keywords : Natural frequency * Striding velocity * Footfall force * Pedestrian dynamics Subject RIV: JM - Building Engineering

  17. Development of Independent Locomotion in Children with a Severe Visual Impairment

    Science.gov (United States)

    Hallemans, Ann; Ortibus, Els; Truijen, Steven; Meire, Francoise

    2011-01-01

    Locomotion of children and adults with a visual impairment (ages 1-44, n = 28) was compared to that of age-related individuals with normal vision (n = 60). Participants walked barefoot at preferred speed while their gait was recorded by a Vicon[R] system. Walking speed, heading angle, step frequency, stride length, step width, stance phase…

  18. KINEMATIC DETERMINANTS OF EARLY ACCELERATION IN FIELD SPORT ATHLETES

    Directory of Open Access Journals (Sweden)

    Robert G. Lockie

    2003-12-01

    Full Text Available Acceleration performance is important for field sport athletes that require a high level of repeat sprint ability. Although acceleration is widely trained for, there is little evidence outlining which kinematic factors delineate between good and poor acceleration. The aim of this study was to investigate the kinematic differences between individuals with fast and slow acceleration. Twenty field sport athletes were tested for sprint ability over the first three steps of a 15m sprint. Subjects were filmed at high speed to determine a range of lower body kinematic measures. For data analysis, subjects were then divided into relatively fast (n = 10 and slow (n = 10 groups based on their horizontal velocity. Groups were then compared across kinematic measures, including stride length and frequency, to determine whether they accounted for observed differences in sprint velocity. The results showed the fast group had significantly lower (~11-13% left and right foot contact times (p < .05, and an increased stride frequency (~9%, as compared to the slow group. Knee extension was also significantly different between groups (p < .05. There was no difference found in stride length. It was concluded that those subjects who are relatively fast in early acceleration achieve this through reduced ground contact times resulting in an improved stride frequency. Training for improved acceleration should be directed towards using coaching instructions and drills that specifically train such movement adaptations

  19. Strategy quantification using body worn inertial sensors in a reactive agility task.

    Science.gov (United States)

    Eke, Chika U; Cain, Stephen M; Stirling, Leia A

    2017-11-07

    Agility performance is often evaluated using time-based metrics, which provide little information about which factors aid or limit success. The objective of this study was to better understand agility strategy by identifying biomechanical metrics that were sensitive to performance speed, which were calculated with data from an array of body-worn inertial sensors. Five metrics were defined (normalized number of foot contacts, stride length variance, arm swing variance, mean normalized stride frequency, and number of body rotations) that corresponded to agility terms defined by experts working in athletic, clinical, and military environments. Eighteen participants donned 13 sensors to complete a reactive agility task, which involved navigating a set of cones in response to a vocal cue. Participants were grouped into fast, medium, and slow performance based on their completion time. Participants in the fast group had the smallest number of foot contacts (normalizing by height), highest stride length variance (normalizing by height), highest forearm angular velocity variance, and highest stride frequency (normalizing by height). The number of body rotations was not sensitive to speed and may have been determined by hand and foot dominance while completing the agility task. The results of this study have the potential to inform the development of a composite agility score constructed from the list of significant metrics. By quantifying the agility terms previously defined by expert evaluators through an agility score, this study can assist in strategy development for training and rehabilitation across athletic, clinical, and military domains. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Changes in running economy following downhill running.

    Science.gov (United States)

    Chen, Trevor C; Nosaka, Kazunori; Tu, Jui-Hung

    2007-01-01

    In this study, we examined the time course of changes in running economy following a 30-min downhill (-15%) run at 70% peak aerobic power (VO2peak). Ten young men performed level running at 65, 75, and 85% VO2peak (5 min for each intensity) before, immediately after, and 1 - 5 days after the downhill run, at which times oxygen consumption (VO2), minute ventilation, the respiratory exchange ratio (RER), heart rate, ratings of perceived exertion (RPE), and blood lactate concentration were measured. Stride length, stride frequency, and range of motion of the ankle, knee, and hip joints during the level runs were analysed using high-speed (120-Hz) video images. Downhill running induced reductions (7 - 21%, P rate, minute ventilation, RER, RPE, blood lactate concentration, and stride frequency, as well as reductions in stride length and range of motion of the ankle and knee. The results suggest that changes in running form and compromised muscle function due to muscle damage contribute to the reduction in running economy for 3 days after downhill running.

  1. Influence of the biomechanical variables of the gait cycle in running economy. [Influencia de variables biomecánicas del ciclo de paso en la economía de carrera].

    Directory of Open Access Journals (Sweden)

    Jordan Santos-Concejero

    2014-04-01

    Full Text Available The aim of this study was to investigate the relationships between biomechanical variables and running economy (RE. Eleven recreational (RR and 14 well-trained runners (WT completed 4 min stages on a treadmill at different speeds. During the test, biomechanical variables such as ground contact time (tc, swing time (tsw, stride length, frequency and angle and the length of the different subphases of ground contact were calculated using an optical measurement system. VO2 was measured in order to calculate RE. The WT runners were more economical than the RR at all speeds and presented lower tc, higher tsw, longer strides, lower stride frequencies and higher stride angles (P Resumen El objetivo de este estudio fue el investigar las relaciones entre diferentes variables biomecánicas y la economía de carrera (RE. Once atletas populares (RR y 14 atletas altamente entrenados (WT completaron estadios de 4 min en tapiz rodante a diferentes velocidades. Durante el test, el tiempo de contacto (tc y de vuelo (tsw, la longitud, frecuencia y ángulo de zancada y la duración de las diferentes sub-fases del tiempo de contacto se calcularon usando un sistema óptico. Se midió el VO2 para calcular la RE. Los atletas WT fueron más económicos que los RR y presentaron menores tc, mayores tsw, zancadas más largas, frecuencias más bajas y ángulos mayores (P

  2. Frequency standards

    CERN Document Server

    Riehle, Fritz

    2006-01-01

    Of all measurement units, frequency is the one that may be determined with the highest degree of accuracy. It equally allows precise measurements of other physical and technical quantities, whenever they can be measured in terms of frequency.This volume covers the central methods and techniques relevant for frequency standards developed in physics, electronics, quantum electronics, and statistics. After a review of the basic principles, the book looks at the realisation of commonly used components. It then continues with the description and characterisation of important frequency standards

  3. Frequency Synthesiser

    NARCIS (Netherlands)

    Drago, Salvatore; Sebastiano, Fabio; Leenaerts, Dominicus M.W.; Breems, Lucien J.; Nauta, Bram

    2016-01-01

    A low power frequency synthesiser circuit (30) for a radio transceiver, the synthesiser circuit comprising: a digital controlled oscillator configured to generate an output signal having a frequency controlled by an input digital control word (DCW); a feedback loop connected between an output and an

  4. Frequency synthesiser

    NARCIS (Netherlands)

    Drago, S.; Sebastiano, Fabio; Leenaerts, Dominicus Martinus Wilhelmus; Breems, Lucien Johannes; Nauta, Bram

    2010-01-01

    A low power frequency synthesiser circuit (30) for a radio transceiver, the synthesiser circuit comprising: a digital controlled oscillator configured to generate an output signal having a frequency controlled by an input digital control word (DCW); a feedback loop connected between an output and an

  5. Do humans optimally exploit redundancy to control step variability in walking?

    Directory of Open Access Journals (Sweden)

    Jonathan B Dingwell

    2010-07-01

    Full Text Available It is widely accepted that humans and animals minimize energetic cost while walking. While such principles predict average behavior, they do not explain the variability observed in walking. For robust performance, walking movements must adapt at each step, not just on average. Here, we propose an analytical framework that reconciles issues of optimality, redundancy, and stochasticity. For human treadmill walking, we defined a goal function to formulate a precise mathematical definition of one possible control strategy: maintain constant speed at each stride. We recorded stride times and stride lengths from healthy subjects walking at five speeds. The specified goal function yielded a decomposition of stride-to-stride variations into new gait variables explicitly related to achieving the hypothesized strategy. Subjects exhibited greatly decreased variability for goal-relevant gait fluctuations directly related to achieving this strategy, but far greater variability for goal-irrelevant fluctuations. More importantly, humans immediately corrected goal-relevant deviations at each successive stride, while allowing goal-irrelevant deviations to persist across multiple strides. To demonstrate that this was not the only strategy people could have used to successfully accomplish the task, we created three surrogate data sets. Each tested a specific alternative hypothesis that subjects used a different strategy that made no reference to the hypothesized goal function. Humans did not adopt any of these viable alternative strategies. Finally, we developed a sequence of stochastic control models of stride-to-stride variability for walking, based on the Minimum Intervention Principle. We demonstrate that healthy humans are not precisely "optimal," but instead consistently slightly over-correct small deviations in walking speed at each stride. Our results reveal a new governing principle for regulating stride-to-stride fluctuations in human walking that acts

  6. Conversion frequence

    International Nuclear Information System (INIS)

    Sauteret, C.

    1987-03-01

    The experimental evidence of short wavelength for laser inertial confinement has strongly increased the interest in high efficiency harmonic conversion of powerful Nd: glass lasers. This work describes our high power harmonic conversion experiments performed using the same laser apparatus for doubling, tripling the three high power 1064 nm P102, OCTAL and PHEBUS lasers. In addition to the understanding the physics of harmonic conversion, this work includes the basic concepts allows us to improve the technique such as non colinear schemes, to extend this method to other frequencies (fourth generation) and to predict some physical limits [fr

  7. GAIT ANALYSIS IN GIANT ANTEATER (MYRMECOPHAGA TRIDACTYLA) WITH THE USE OF A PRESSURE-SENSITIVE WALKWAY.

    Science.gov (United States)

    de Faria, Luís Guilherme; Rahal, Sheila Canevese; dos Reis Mesquita, Luciane; Agostinho, Felipe Stefan; Kano, Washington Takashi; Teixeira, Carlos Roberto; Monteiro, Frederico Ozanan Barros

    2015-06-01

    The aim of this study was to evaluate the kinetic and temporospatial parameters of clinically healthy juvenile giant anteaters (Myrmecophaga tridactyla) by using a pressure-sensing walkway. Three free-ranging clinically healthy giant anteaters (M. tridactyla), two males and one female, aged 5-7 mo, were used. There was no statistically significant difference between the right and left sides for the kinetic and temporospatial parameters for both forelimbs and hind limbs. Although the gait velocity was similar for all giant anteaters, the stride frequency was higher in the smaller anteaters. The difference in stride frequency is associated with body size, which also influenced other temporospatial parameters. The percentage of body distribution was higher on the forelimbs than the hind limbs. The contact surface and trajectory of the force of the forepaws differed from the hind paws. In conclusion, the anteaters have gait peculiarities associated with the anatomical differences between forelimbs and hind limbs.

  8. Walking on a Vertically Oscillating Treadmill: Phase Synchronization and Gait Kinematics.

    Directory of Open Access Journals (Sweden)

    Jeff A Nessler

    Full Text Available Sensory motor synchronization can be used to alter gait behavior. This type of therapy may be useful in a rehabilitative setting, though several questions remain regarding the most effective way to promote and sustain synchronization. The purpose of this study was to describe a new technique for using synchronization to influence a person's gait and to compare walking behavior under this paradigm with that of side by side walking. Thirty one subjects walked on a motorized treadmill that was placed on a platform that oscillated vertically at various frequencies and amplitudes. Synchronization with the platform and stride kinematics were recorded during these walking trials and compared with previously reported data from side by side walking. The results indicated that vertical oscillation of the treadmill surface at frequencies that matched subjects preferred stride or step frequency resulted in greater unintentional synchronization when compared with side by side walking data (up to 78.6±8.3% of the trial vs 59.2±17.4%. While intermittent phase locking was observed in all cases, periods of synchronization occurred more frequently and lasted longer while walking on the oscillating treadmill (mean length of periods of phase locking 11.85 steps vs 5.18 steps. Further, stride length, height and duration were altered by changing the frequency of treadmill oscillation. These results suggest that synchronization to a haptic signal may hold implications for use in a clinical setting.

  9. Mechanics of a rapid running insect: two-, four- and six-legged locomotion.

    Science.gov (United States)

    Full, R J; Tu, M S

    1991-03-01

    To examine the effects of variation in body form on the mechanics of terrestrial locomotion, we used a miniature force platform to measure the ground reaction forces of the smallest and, relative to its mass, one of the fastest invertebrates ever studied, the American cockroach Periplaneta americana (mass = 0.83 g). From 0.44-1.0 ms-1, P. americana used an alternating tripod stepping pattern. Fluctuations in gravitational potential energy and horizontal kinetic energy of the center of mass were nearly in phase, characteristic of a running or bouncing gait. Aerial phases were observed as vertical ground reaction force approached zero at speeds above 1 ms-1. At the highest speeds (1.0-1.5 ms-1 or 50 body lengths per second), P. americana switched to quadrupedal and bipedal running. Stride frequency approached the wing beat frequencies used during flight (27 Hz). High speeds were attained by increasing stride length, whereas stride frequency showed little increase with speed. The mechanical power used to accelerate the center of mass increased curvilinearly with speed. The mass-specific mechanical energy used to move the center of mass a given distance was similar to that measured for animals five orders of magnitude larger in mass, but was only one-hundredth of the metabolic cost.

  10. The biomechanic origin of sprint performance enhancement after one-week creatine supplementation.

    Science.gov (United States)

    Schedel, J M; Terrier, P; Schutz, Y

    2000-04-01

    In order to test whether an improvement of maximal sprinting speed after creatine (Cr) supplementation was due to the increase of stride frequency (SF), stride length (SL) or both, 7 subjects ran 4 consecutive sprints after 1 week of placebo or Cr supplementation. SF and SL were assessed by a triaxial accelerometer. Compared to the placebo, Cr induced an increase of running speed (+1.4% p < 0.05) and SF (+1.5%, p < 0.01), but not of SL. The drop in performance following repeated sprints was partially prevented by Cr. In conclusion, exogenous Cr enhanced sprinting performance by increasing SF. This result may be related to the recent findings of shortening in muscular relaxation time after Cr supplementation.

  11. High speed galloping in the cheetah (Acinonyx jubatus) and the racing greyhound (Canis familiaris): spatio-temporal and kinetic characteristics.

    Science.gov (United States)

    Hudson, Penny E; Corr, Sandra A; Wilson, Alan M

    2012-07-15

    The cheetah and racing greyhound are of a similar size and gross morphology and yet the cheetah is able to achieve a far higher top speed. We compared the kinematics and kinetics of galloping in the cheetah and greyhound to investigate how the cheetah can attain such remarkable maximum speeds. This also presented an opportunity to investigate some of the potential limits to maximum running speed in quadrupeds, which remain poorly understood. By combining force plate and high speed video data of galloping cheetahs and greyhounds, we show how the cheetah uses a lower stride frequency/longer stride length than the greyhound at any given speed. In some trials, the cheetahs used swing times as low as those of the greyhounds (0.2 s) so the cheetah has scope to use higher stride frequencies (up to 4.0 Hz), which may contribute to it having a higher top speed that the greyhound. Weight distribution between the animal's limbs varied with increasing speed. At high speed, the hindlimbs support the majority of the animal's body weight, with the cheetah supporting 70% of its body weight on its hindlimbs at 18 m s(-1); however, the greyhound hindlimbs support just 62% of its body weight. Supporting a greater proportion of body weight on a particular limb is likely to reduce the risk of slipping during propulsive efforts. Our results demonstrate several features of galloping and highlight differences between the cheetah and greyhound that may account for the cheetah's faster maximum speeds.

  12. Dynamic markers of altered gait rhythm in amyotrophic lateral sclerosis

    Science.gov (United States)

    Hausdorff, J. M.; Lertratanakul, A.; Cudkowicz, M. E.; Peterson, A. L.; Kaliton, D.; Goldberger, A. L.

    2000-01-01

    Amyotrophic lateral sclerosis (ALS) is a disorder marked by loss of motoneurons. We hypothesized that subjects with ALS would have an altered gait rhythm, with an increase in both the magnitude of the stride-to-stride fluctuations and perturbations in the fluctuation dynamics. To test for this locomotor instability, we quantitatively compared the gait rhythm of subjects with ALS with that of normal controls and with that of subjects with Parkinson's disease (PD) and Huntington's disease (HD), pathologies of the basal ganglia. Subjects walked for 5 min at their usual pace wearing an ankle-worn recorder that enabled determination of the duration of each stride and of stride-to-stride fluctuations. We found that the gait of patients with ALS is less steady and more temporally disorganized compared with that of healthy controls. In addition, advanced ALS, HD, and PD were associated with certain common, as well as apparently distinct, features of altered stride dynamics. Thus stride-to-stride control of gait rhythm is apparently compromised with ALS. Moreover, a matrix of markers based on gait dynamics may be useful in characterizing certain pathologies of motor control and, possibly, in quantitatively monitoring disease progression and evaluating therapeutic interventions.

  13. Greenwashing: Knowing Is Half the Battle

    Science.gov (United States)

    Neugebauer, Adam

    2011-01-01

    The growing interest in "green" products in recent years has been met stride-for-stride with marketing campaigns attempting to tap into that trend. This once-niche sector was finally becoming mainstream and the market scrambled to meet that demand. Companies and organizations took steps to make themselves and their products and services more…

  14. Kick, Glide, Pole! Cross-Country Skiing Fun (Part II)

    Science.gov (United States)

    Duoos, Bridget A.

    2012-01-01

    Part I of Kick, Glide, Pole! Cross-Country Skiing Fun, which was published in last issue, discussed how to select cross-country ski equipment, dress for the activity and the biomechanics of the diagonal stride. Part II focuses on teaching the diagonal stride technique and begins with a progression of indoor activities. Incorporating this fun,…

  15. Frequency noise in frequency swept fiber laser

    DEFF Research Database (Denmark)

    Pedersen, Anders Tegtmeier; Rottwitt, Karsten

    2013-01-01

    This Letter presents a measurement of the spectral content of frequency shifted pulses generated by a lightwave synthesized frequency sweeper. We found that each pulse is shifted in frequency with very high accuracy. We also discovered that noise originating from light leaking through the acousto...

  16. Estimation of Spatial-Temporal Gait Parameters Using a Low-Cost Ultrasonic Motion Analysis System

    Directory of Open Access Journals (Sweden)

    Yongbin Qi

    2014-08-01

    Full Text Available In this paper, a low-cost motion analysis system using a wireless ultrasonic sensor network is proposed and investigated. A methodology has been developed to extract spatial-temporal gait parameters including stride length, stride duration, stride velocity, stride cadence, and stride symmetry from 3D foot displacements estimated by the combination of spherical positioning technique and unscented Kalman filter. The performance of this system is validated against a camera-based system in the laboratory with 10 healthy volunteers. Numerical results show the feasibility of the proposed system with average error of 2.7% for all the estimated gait parameters. The influence of walking speed on the measurement accuracy of proposed system is also evaluated. Statistical analysis demonstrates its capability of being used as a gait assessment tool for some medical applications.

  17. Estimation of spatial-temporal gait parameters using a low-cost ultrasonic motion analysis system.

    Science.gov (United States)

    Qi, Yongbin; Soh, Cheong Boon; Gunawan, Erry; Low, Kay-Soon; Thomas, Rijil

    2014-08-20

    In this paper, a low-cost motion analysis system using a wireless ultrasonic sensor network is proposed and investigated. A methodology has been developed to extract spatial-temporal gait parameters including stride length, stride duration, stride velocity, stride cadence, and stride symmetry from 3D foot displacements estimated by the combination of spherical positioning technique and unscented Kalman filter. The performance of this system is validated against a camera-based system in the laboratory with 10 healthy volunteers. Numerical results show the feasibility of the proposed system with average error of 2.7% for all the estimated gait parameters. The influence of walking speed on the measurement accuracy of proposed system is also evaluated. Statistical analysis demonstrates its capability of being used as a gait assessment tool for some medical applications.

  18. Differences in ground contact time explain the less efficient running economy in north african runners.

    Science.gov (United States)

    Santos-Concejero, J; Granados, C; Irazusta, J; Bidaurrazaga-Letona, I; Zabala-Lili, J; Tam, N; Gil, S M

    2013-09-01

    The purpose of this study was to investigate the relationship between biomechanical variables and running economy in North African and European runners. Eight North African and 13 European male runners of the same athletic level ran 4-minute stages on a treadmill at varying set velocities. During the test, biomechanical variables such as ground contact time, swing time, stride length, stride frequency, stride angle and the different sub-phases of ground contact were recorded using an optical measurement system. Additionally, oxygen uptake was measured to calculate running economy. The European runners were more economical than the North African runners at 19.5 km · h(-1), presented lower ground contact time at 18 km · h(-1) and 19.5 km · h(-1) and experienced later propulsion sub-phase at 10.5 km · h(-1),12 km · h(-1), 15 km · h(-1), 16.5 km · h(-1) and 19.5 km · h(-1) than the European runners (P Running economy at 19.5 km · h(-1) was negatively correlated with swing time (r = -0.53) and stride angle (r = -0.52), whereas it was positively correlated with ground contact time (r = 0.53). Within the constraints of extrapolating these findings, the less efficient running economy in North African runners may imply that their outstanding performance at international athletic events appears not to be linked to running efficiency. Further, the differences in metabolic demand seem to be associated with differing biomechanical characteristics during ground contact, including longer contact times.

  19. Lower limb mechanics during moderate high-heel jogging and running in different experienced wearers.

    Science.gov (United States)

    Fu, Fengqin; Zhang, Yan; Shu, Yang; Ruan, Guoqing; Sun, Jianjun; Baker, Julien S; Gu, Yaodong

    2016-08-01

    The aim of this study is to investigate the differences in lower limb kinematics and kinetics between experienced (EW) and inexperienced (IEW) moderate high-heel wearers during jogging and running. Eleven experienced female wearers of moderate high-heel shoes and eleven matched controls participated in jogging and running tests. A Vicon motion analysis system was used to capture kinematic data and a Kistler force platform was used to collect ground reaction force (GRF). There were no significant differences in jogging and running speed respectively. Compared with IEW, EW adopted larger stride length (SL) with lower stride frequency (SF) at each corresponding speed. During running, EW enlarged SL significantly while IEW increased both SL and SF significantly. Kinematic data showed that IEW had generally larger joint range of motion (ROM) and peak angles during stance phase. Speed effect was not obvious within IEW. EW exhibited a significantly increased maximal vertical GRF (Fz2) and vertical average loading rate (VALR) during running, which was potentially caused by overlong stride. These suggest that both EW and IEW are at high risk of joint injuries when running on moderate high heels. For wearers who have to do some running on moderate high heels, it is crucial to control joint stability and balance SL and SF consciously. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. DIFFERENCES IN KINEMATIC PARAMETERS OF ATHLETES OF DIFFERENT RUNNING QUALITY

    Directory of Open Access Journals (Sweden)

    V Babić

    2011-06-01

    Full Text Available The aim of the study was to determine the differences among subjects of different sprinting quality in the variables of running dynamics in the 100 m sprint event and in the variables of kinematic indicators (stride frequency, stride length, foot-ground contact duration, airborne phase duration. The research was conducted on a sample of 133 physical education teacher male students, aged 19 to 24 years (age 21.7 ± 1.08 yrs; body height 180.8 ± 6.98 cm; body mass 76.6 ± 7.62 kg, first year students at the Faculty of Kinesiology, University of Zagreb, who regularly attended their athletics classes. Basic descriptive statistical parameters were computed. Cluster analysis was used to determine sprinting-quality-based homogeneous groups of subjects. The qualitative differences among the subjects pertaining to the defined groups were established by canonical discriminant analysis. One significant discriminant function was obtained differentiating the group of students who performed well from all the other groups of students with poorer sprint performance. The best performance group demonstrated running technique characterised by the shortest foot-ground contact time in the phases of starting acceleration and maximum speed running, and a larger stride length in the phase of maximum speed running.

  1. Multiple Frequency Parametric Sonar

    Science.gov (United States)

    2015-09-28

    300003 1 MULTIPLE FREQUENCY PARAMETRIC SONAR STATEMENT OF GOVERNMENT INTEREST [0001] The invention described herein may be manufactured and...a method for increasing the bandwidth of a parametric sonar system by using multiple primary frequencies rather than only two primary frequencies...2) Description of Prior Art [0004] Parametric sonar generates narrow beams at low frequencies by projecting sound at two distinct primary

  2. Multi-frequency excitation

    KAUST Repository

    Younis, Mohammad I.

    2016-03-10

    Embodiments of multi-frequency excitation are described. In various embodiments, a natural frequency of a device may be determined. In turn, a first voltage amplitude and first fixed frequency of a first source of excitation can be selected for the device based on the natural frequency. Additionally, a second voltage amplitude of a second source of excitation can be selected for the device, and the first and second sources of excitation can be applied to the device. After applying the first and second sources of excitation, a frequency of the second source of excitation can be swept. Using the methods of multi- frequency excitation described herein, new operating frequencies, operating frequency ranges, resonance frequencies, resonance frequency ranges, and/or resonance responses can be achieved for devices and systems.

  3. Frequency selectivity at very low centre frequencies

    DEFF Research Database (Denmark)

    Orellana, Carlos Andrés Jurado; Pedersen, Christian Sejer; Marquardt, Torsten

    2010-01-01

    measurements based on OAE suppression techniques and notched-noise masking data psychophysically measured for centre frequencies in the range 50-125 Hz, this study examines how individual differences in frequency selectivity, as well as in masking, may occur at very low CFs due to individual differences...

  4. Frequency dependence of sonophoresis.

    Science.gov (United States)

    Tezel, A; Sens, A; Tuchscherer, J; Mitragotri, S

    2001-12-01

    Application of low-frequency ultrasound has been shown to increase skin permeability, thereby facilitating delivery of macromolecules (low-frequency sonophoresis). In this study, we sought to determine the dependence of low-frequency sonophoresis on ultrasound frequency, intensity and energy density. Pig skin was exposed to low-frequency ultrasound over a range of ultrasound frequency and intensity conditions. The degree of skin permeabilization was measured using its conductivity. Imaging experiments were also carried out to visualize the transport pathways created by ultrasound. The data showed that for each frequency (in the range of 19.6-93.4 kHz), there exists a threshold intensity below which no detectable conductivity enhancement was observed. The threshold intensity increased with frequency. It is feasible to achieve the desired conductivity (permeability) enhancement regardless of the choice of frequency, although the necessary energy density is higher at higher frequencies. Low frequencies (approximately 20 kHz) induced localized transport compared to a more dispersed effect seen with higher frequencies (approximately 58.9 kHz). This study provides a quantitative understanding of the effects of low-frequency ultrasound on skin permeability.

  5. Lunch frequency among adolescents

    DEFF Research Database (Denmark)

    Pedersen, Trine Pagh; Holstein, Bjørn E; Krølner, Rikke

    2016-01-01

    OBJECTIVE: To investigate: (i) how lunch frequency of adolescents varies between schools and between classes within schools; (ii) the associations between frequency of lunch and individual sociodemographic factors and school characteristics; and (iii) if any observed associations between lunch...

  6. Modeling Frequency Comb Sources

    Directory of Open Access Journals (Sweden)

    Li Feng

    2016-06-01

    Full Text Available Frequency comb sources have revolutionized metrology and spectroscopy and found applications in many fields. Stable, low-cost, high-quality frequency comb sources are important to these applications. Modeling of the frequency comb sources will help the understanding of the operation mechanism and optimization of the design of such sources. In this paper,we review the theoretical models used and recent progress of the modeling of frequency comb sources.

  7. Frequency reference in VSAT

    Science.gov (United States)

    Cheah, Jonathon Y. C.

    1994-02-01

    A low cost technique of frequency reference distribution within a VSAT network is discussed. This technique allows the use of a modestly frequency stable oscillator as the master frequency reference in the hub of a star-connected VSAT network. The need for extremely frequency stable OCXOs in VSATs is completely avoided. This technique was successfully incorporated in the early commercial VSAT networks. It contributes partially to the low cost nature of some of the VSAT networks available today.

  8. Static electromagnetic frequency changers

    CERN Document Server

    Rozhanskii, L L

    1963-01-01

    Static Electromagnetic Frequency Changers is about the theory, design, construction, and applications of static electromagnetic frequency changers, devices that used for multiplication or division of alternating current frequency. It is originally published in the Russian language. This book is organized into five chapters. The first three chapters introduce the readers to the principles of operation, the construction, and the potential applications of static electromagnetic frequency changers and to the principles of their design. The two concluding chapters use some hitherto unpublished work

  9. Eastern Frequency Response Study

    Energy Technology Data Exchange (ETDEWEB)

    Miller, N.W.; Shao, M.; Pajic, S.; D' Aquila, R.

    2013-05-01

    This study was specifically designed to investigate the frequency response of the Eastern Interconnection that results from large loss-of-generation events of the type targeted by the North American Electric Reliability Corp. Standard BAL-003 Frequency Response and Frequency Bias Setting (NERC 2012a), under possible future system conditions with high levels of wind generation.

  10. Making Sense of Frequency.

    Science.gov (United States)

    Larsen-Freeman, Diane

    2002-01-01

    Responds to Ellis (2002), which focuses on frequency in language processing, language use, and language acquisition. Contextualizes the frequency factor in terms of the evolution of second language acquisition (SLA) research. Suggests that although relevant and important, the frequency factor requires greater definition and qualification.…

  11. Continuous Static Gait with Twisting Trunk of a Metamorphic Quadruped Robot

    Directory of Open Access Journals (Sweden)

    C. Zhang

    2018-01-01

    Full Text Available The natural quadrupeds, such as geckos and lizards, often twist their trunks when moving. Conventional quadruped robots cannot perform the same motion due to equipping with a trunk which is a rigid body or at most consists of two blocks connected by passive joints. This paper proposes a metamorphic quadruped robot with a reconfigurable trunk which can implement active trunk motions, called MetaRobot I. The robot can imitate the natural quadrupeds to execute motion of trunk twisting. Benefiting from the twisting trunk, the stride length of this quadruped is increased comparing to that of conventional quadruped robots.In this paper a continuous static gait benefited from the twisting trunk performing the increased stride length is introduced. After that, the increased stride length relative to the trunk twisting will be analysed mathematically. Other points impacting the implementation of the increased stride length in the gait are investigated such as the upper limit of the stride length and the kinematic margin. The increased stride length in the gait will lead the increase of locomotion speed comparing with conventional quadruped robots, giving the extent that natural quadrupeds twisting their trunks when moving. The simulation and an experiment on the prototype are then carried out to illustrate the benefits on the stride length and locomotion speed brought by the twisting trunk to the quadruped robot.

  12. The Use of Simulation Training to Accelerate the Rate of Forward Ice Skating Skill Acquisition

    Directory of Open Access Journals (Sweden)

    Nathan J Washington

    2016-04-01

    Full Text Available Background: Australia’s interest and participation in ice hockey is increasing, however a lack of access to facilities means familiarity with this sport is limited, and so too is the facilitation of skill development within an ecologically valid context. Objective: While numerous methods may be employed to address this, one resource which remains relatively unexplored is the StrideDeck Treadmill, therefore the purpose of this study was to investigate the effectiveness of this equipment with specific reference to the biomechanical changes for skating ability. Methods: N = 16 male athletes (Mage = 15.0 ± 0.76 yrs from a junior league competition participated in this intervention based study. n = 9 were assigned to the training intervention (StrideDeck once a week, while the control group (n = 7 continued their normal training routines. Further, monthly sprint tests both on the StrideDeck and an on-ice protocol were conducted to track progress via kinematic analysis. Results: Data analysis revealed no significant overall effects for on-ice sprint skating performance after StrideDeck training; however there were significant kinematic differences between StrideDeck and ice conditions. Conclusions: Therefore while the StrideDeck may have merit in regard to physiological paramters, the results of this study do not support its use as a skill acquisition tool in regard to increasing skating ability. Keywords: Simulation training, skill acquisition, treadmill, ice skating, ice hockey skating, ice skating stride

  13. Acute and Chronic Effect of Acoustic and Visual Cues on Gait Training in Parkinson’s Disease: A Randomized, Controlled Study

    Directory of Open Access Journals (Sweden)

    Roberto De Icco

    2015-01-01

    Full Text Available In this randomized controlled study we analyse and compare the acute and chronic effects of visual and acoustic cues on gait performance in Parkinson’s Disease (PD. We enrolled 46 patients with idiopathic PD who were assigned to 3 different modalities of gait training: (1 use of acoustic cues, (2 use of visual cues, or (3 overground training without cues. All patients were tested with kinematic analysis of gait at baseline (T0, at the end of the 4-week rehabilitation programme (T1, and 3 months later (T2. Regarding the acute effect, acoustic cues increased stride length and stride duration, while visual cues reduced the number of strides and normalized the stride/stance distribution but also reduced gait speed. As regards the chronic effect of cues, we recorded an improvement in some gait parameters in all 3 groups of patients: all 3 types of training improved gait speed; visual cues also normalized the stance/swing ratio, acoustic cues reduced the number of strides and increased stride length, and overground training improved stride length. The changes were not retained at T2 in any of the experimental groups. Our findings support and characterize the usefulness of cueing strategies in the rehabilitation of gait in PD.

  14. Radio frequency detection assembly and method for detecting radio frequencies

    Science.gov (United States)

    Cown, Steven H.; Derr, Kurt Warren

    2010-03-16

    A radio frequency detection assembly is described and which includes a radio frequency detector which detects a radio frequency emission produced by a radio frequency emitter from a given location which is remote relative to the radio frequency detector; a location assembly electrically coupled with the radio frequency detector and which is operable to estimate the location of the radio frequency emitter from the radio frequency emission which has been received; and a radio frequency transmitter electrically coupled with the radio frequency detector and the location assembly, and which transmits a radio frequency signal which reports the presence of the radio frequency emitter.

  15. Waveform frequency notching

    Science.gov (United States)

    Doerry, Armin W.; Andrews, John

    2017-05-09

    The various technologies presented herein relate to incorporating one or more notches into a radar spectrum, whereby the notches relate to one or more frequencies for which no radar transmission is to occur. An instantaneous frequency is monitored and if the frequency is determined to be of a restricted frequency, then a radar signal can be modified. Modification can include replacing the signal with a signal having a different instantaneous amplitude, a different instantaneous phase, etc. The modification can occur in a WFS prior to a DAC, as well as prior to a sin ROM component and/or a cos ROM component. Further, the notch can be dithered to enable formation of a deep notch. The notch can also undergo signal transitioning to enable formation of a deep notch. The restricted frequencies can be stored in a LUT against which an instantaneous frequency can be compared.

  16. LOW FREQUENCY DAMPER

    Directory of Open Access Journals (Sweden)

    Radu BOGATEANU

    2009-09-01

    Full Text Available The low frequency damper is an autonomous equipment for damping vibrations with the 1-20Hz range.Its autonomy enables the equipment to be located in various mechanical systems, without requiring special hydraulic installations.The low frequency damper was designed for damping the low frequency oscillations occurring in the circuit controls of the upgraded IAR-99 Aircraft.The low frequency damper is a novelty in the aerospace field ,with applicability in several areas as it can be built up in an appropriate range of dimensions meeting the requirements of different beneficiaries. On this line an equipment able to damp an extended frequency range was performed for damping oscillations in the pipes of the nuclear power plants.This damper, tested in INCAS laboratories matched the requirements of the beneficiary.The low frequency damper is patented – the patent no. 114583C1/2000 is held by INCAS.

  17. Frequency Response Analysis Tool

    Energy Technology Data Exchange (ETDEWEB)

    Etingov, Pavel V. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Kosterev, Dmitry [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Dai, T. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2014-12-01

    Frequency response has received a lot of attention in recent years at the national level, which culminated in the development and approval of North American Electricity Reliability Corporation (NERC) BAL-003-1 Frequency Response and Frequency Bias Setting Reliability Standard. This report is prepared to describe the details of the work conducted by Pacific Northwest National Laboratory (PNNL) in collaboration with the Bonneville Power Administration and Western Electricity Coordinating Council (WECC) Joint Synchronized Information Subcommittee (JSIS) to develop a frequency response analysis tool (FRAT). The document provides the details on the methodology and main features of the FRAT. The tool manages the database of under-frequency events and calculates the frequency response baseline. Frequency response calculations are consistent with frequency response measure (FRM) in NERC BAL-003-1 for an interconnection and balancing authority. The FRAT can use both phasor measurement unit (PMU) data, where available, and supervisory control and data acquisition (SCADA) data. The tool is also capable of automatically generating NERC Frequency Response Survey (FRS) forms required by BAL-003-1 Standard.

  18. Nonlinear Frequency Compression

    Science.gov (United States)

    Scollie, Susan; Glista, Danielle; Seelisch, Andreas

    2013-01-01

    Frequency lowering technologies offer an alternative amplification solution for severe to profound high frequency hearing losses. While frequency lowering technologies may improve audibility of high frequency sounds, the very nature of this processing can affect the perceived sound quality. This article reports the results from two studies that investigated the impact of a nonlinear frequency compression (NFC) algorithm on perceived sound quality. In the first study, the cutoff frequency and compression ratio parameters of the NFC algorithm were varied, and their effect on the speech quality was measured subjectively with 12 normal hearing adults, 12 normal hearing children, 13 hearing impaired adults, and 9 hearing impaired children. In the second study, 12 normal hearing and 8 hearing impaired adult listeners rated the quality of speech in quiet, speech in noise, and music after processing with a different set of NFC parameters. Results showed that the cutoff frequency parameter had more impact on sound quality ratings than the compression ratio, and that the hearing impaired adults were more tolerant to increased frequency compression than normal hearing adults. No statistically significant differences were found in the sound quality ratings of speech-in-noise and music stimuli processed through various NFC settings by hearing impaired listeners. These findings suggest that there may be an acceptable range of NFC settings for hearing impaired individuals where sound quality is not adversely affected. These results may assist an Audiologist in clinical NFC hearing aid fittings for achieving a balance between high frequency audibility and sound quality. PMID:23539261

  19. Frequency Selective Reflector Antenna

    Data.gov (United States)

    National Aeronautics and Space Administration — Frequency Selective Surfaces (FSS) are an electromagnetic structure where a relatively thin, periodic, conductive material is designed as a spatial filter of...

  20. Gait variability: methods, modeling and meaning

    Directory of Open Access Journals (Sweden)

    Hausdorff Jeffrey M

    2005-07-01

    Full Text Available Abstract The study of gait variability, the stride-to-stride fluctuations in walking, offers a complementary way of quantifying locomotion and its changes with aging and disease as well as a means of monitoring the effects of therapeutic interventions and rehabilitation. Previous work has suggested that measures of gait variability may be more closely related to falls, a serious consequence of many gait disorders, than are measures based on the mean values of other walking parameters. The Current JNER series presents nine reports on the results of recent investigations into gait variability. One novel method for collecting unconstrained, ambulatory data is reviewed, and a primer on analysis methods is presented along with a heuristic approach to summarizing variability measures. In addition, the first studies of gait variability in animal models of neurodegenerative disease are described, as is a mathematical model of human walking that characterizes certain complex (multifractal features of the motor control's pattern generator. Another investigation demonstrates that, whereas both healthy older controls and patients with a higher-level gait disorder walk more slowly in reduced lighting, only the latter's stride variability increases. Studies of the effects of dual tasks suggest that the regulation of the stride-to-stride fluctuations in stride width and stride time may be influenced by attention loading and may require cognitive input. Finally, a report of gait variability in over 500 subjects, probably the largest study of this kind, suggests how step width variability may relate to fall risk. Together, these studies provide new insights into the factors that regulate the stride-to-stride fluctuations in walking and pave the way for expanded research into the control of gait and the practical application of measures of gait variability in the clinical setting.

  1. Segmentation of Gait Sequences in Sensor-Based Movement Analysis: A Comparison of Methods in Parkinson's Disease.

    Science.gov (United States)

    Haji Ghassemi, Nooshin; Hannink, Julius; Martindale, Christine F; Gaßner, Heiko; Müller, Meinard; Klucken, Jochen; Eskofier, Björn M

    2018-01-06

    Robust gait segmentation is the basis for mobile gait analysis. A range of methods have been applied and evaluated for gait segmentation of healthy and pathological gait bouts. However, a unified evaluation of gait segmentation methods in Parkinson's disease (PD) is missing. In this paper, we compare four prevalent gait segmentation methods in order to reveal their strengths and drawbacks in gait processing. We considered peak detection from event-based methods, two variations of dynamic time warping from template matching methods, and hierarchical hidden Markov models (hHMMs) from machine learning methods. To evaluate the methods, we included two supervised and instrumented gait tests that are widely used in the examination of Parkinsonian gait. In the first experiment, a sequence of strides from instructed straight walks was measured from 10 PD patients. In the second experiment, a more heterogeneous assessment paradigm was used from an additional 34 PD patients, including straight walks and turning strides as well as non-stride movements. The goal of the latter experiment was to evaluate the methods in challenging situations including turning strides and non-stride movements. Results showed no significant difference between the methods for the first scenario, in which all methods achieved an almost 100% accuracy in terms of F-score. Hence, we concluded that in the case of a predefined and homogeneous sequence of strides, all methods can be applied equally. However, in the second experiment the difference between methods became evident, with the hHMM obtaining a 96% F-score and significantly outperforming the other methods. The hHMM also proved promising in distinguishing between strides and non-stride movements, which is critical for clinical gait analysis. Our results indicate that both the instrumented test procedure and the required stride segmentation algorithm have to be selected adequately in order to support and complement classical clinical examination

  2. The Effects of Music Salience on the Gait Performance of Young Adults.

    Science.gov (United States)

    de Bruin, Natalie; Kempster, Cody; Doucette, Angelica; Doan, Jon B; Hu, Bin; Brown, Lesley A

    2015-01-01

    The presence of a rhythmic beat in the form of a metronome tone or beat-accentuated original music can modulate gait performance; however, it has yet to be determined whether gait modulation can be achieved using commercially available music. The current study investigated the effects of commercially available music on the walking of healthy young adults. Specific aims were (a) to determine whether commercially available music can be used to influence gait (i.e., gait velocity, stride length, cadence, stride time variability), (b) to establish the effect of music salience on gait (i.e., gait velocity, stride length, cadence, stride time variability), and (c) to examine whether music tempi differentially effected gait (i.e., gait velocity, stride length, cadence, stride time variability). Twenty-five participants walked the length of an unobstructed walkway while listening to music. Music selections differed with respect to the salience or the tempo of the music. The genre of music and artists were self-selected by participants. Listening to music while walking was an enjoyable activity that influenced gait. Specifically, salient music selections increased measures of cadence, velocity, and stride length; in contrast, gait was unaltered by the presence of non-salient music. Music tempo did not differentially affect gait performance (gait velocity, stride length, cadence, stride time variability) in these participants. Gait performance was differentially influenced by music salience. These results have implications for clinicians considering the use of commercially available music as an alternative to the traditional rhythmic auditory cues used in rehabilitation programs. © the American Music Therapy Association 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  3. Segmentation of Gait Sequences in Sensor-Based Movement Analysis: A Comparison of Methods in Parkinson’s Disease

    Directory of Open Access Journals (Sweden)

    Nooshin Haji Ghassemi

    2018-01-01

    Full Text Available Robust gait segmentation is the basis for mobile gait analysis. A range of methods have been applied and evaluated for gait segmentation of healthy and pathological gait bouts. However, a unified evaluation of gait segmentation methods in Parkinson’s disease (PD is missing. In this paper, we compare four prevalent gait segmentation methods in order to reveal their strengths and drawbacks in gait processing. We considered peak detection from event-based methods, two variations of dynamic time warping from template matching methods, and hierarchical hidden Markov models (hHMMs from machine learning methods. To evaluate the methods, we included two supervised and instrumented gait tests that are widely used in the examination of Parkinsonian gait. In the first experiment, a sequence of strides from instructed straight walks was measured from 10 PD patients. In the second experiment, a more heterogeneous assessment paradigm was used from an additional 34 PD patients, including straight walks and turning strides as well as non-stride movements. The goal of the latter experiment was to evaluate the methods in challenging situations including turning strides and non-stride movements. Results showed no significant difference between the methods for the first scenario, in which all methods achieved an almost 100% accuracy in terms of F-score. Hence, we concluded that in the case of a predefined and homogeneous sequence of strides, all methods can be applied equally. However, in the second experiment the difference between methods became evident, with the hHMM obtaining a 96% F-score and significantly outperforming the other methods. The hHMM also proved promising in distinguishing between strides and non-stride movements, which is critical for clinical gait analysis. Our results indicate that both the instrumented test procedure and the required stride segmentation algorithm have to be selected adequately in order to support and complement classical

  4. Frequency Mapping for the Operational Frequency Manager

    Science.gov (United States)

    2008-03-01

    and stationary computers. 1990s Late in the decade, Virtual Private Networks ( VPNs ) based on the Layer 2 Tunneling Protocol (L2TP) and IPSEC ...L2TP – Layer Two Tunnel Protocol LBNL – Lawrence Berkeley National Lab MHZ – Megahertz MIO – Maritime Interdiction Operations NOC – Network...Vehicle UHF – Ultra-High Frequency VPN – Virtual Private Network xvii ACKNOWLEDGMENTS First and foremost, we would like to thank our spouses Fatima

  5. Fast fundamental frequency estimation

    DEFF Research Database (Denmark)

    Nielsen, Jesper Kjær; Jensen, Tobias Lindstrøm; Jensen, Jesper Rindom

    2017-01-01

    Modelling signals as being periodic is common in many applications. Such periodic signals can be represented by a weighted sum of sinusoids with frequencies being an integer multiple of the fundamental frequency. Due to its widespread use, numerous methods have been proposed to estimate the funda...

  6. Electrothermal frequency reference

    NARCIS (Netherlands)

    Makinwa, K.A.A.; Kashmiri, S.M.

    2011-01-01

    An electrothermal frequency-locked loop (EFLL) circuit is described. This EFLL circuit includes an oscillator in a feedback loop. A drive circuit in the EFLL circuit generates a first signal having a fundamental frequency, and an electrothermal filter (ETF) in the EFLL circuit provides a second

  7. Single frequency intracavity SRO

    DEFF Research Database (Denmark)

    Abitan, Haim; Buchhave, Preben

    2000-01-01

    Summary form only given. A single resonance optical parametric oscillator (SRO) is inserted intracavity to a CW high power, single frequency, and ring Nd:YVO4 laser. We obtain a stable single frequency CW SRO with output at 1.7-1.9 μm (idler) and a resonating signal at 2.3-2.6 μm. The behavior...

  8. Microfabricated ion frequency standard

    Science.gov (United States)

    Schwindt, Peter; Biedermann, Grant; Blain, Matthew G.; Stick, Daniel L.; Serkland, Darwin K.; Olsson, III, Roy H.

    2010-12-28

    A microfabricated ion frequency standard (i.e. an ion clock) is disclosed with a permanently-sealed vacuum package containing a source of ytterbium (Yb) ions and an octupole ion trap. The source of Yb ions is a micro-hotplate which generates Yb atoms which are then ionized by a ultraviolet light-emitting diode or a field-emission electron source. The octupole ion trap, which confines the Yb ions, is formed from suspended electrodes on a number of stacked-up substrates. A microwave source excites a ground-state transition frequency of the Yb ions, with a frequency-doubled vertical-external-cavity laser (VECSEL) then exciting the Yb ions up to an excited state to produce fluorescent light which is used to tune the microwave source to the ground-state transition frequency, with the microwave source providing a precise frequency output for the ion clock.

  9. Breakfast frequency among adolescents

    DEFF Research Database (Denmark)

    Pedersen, Trine Pagh; Holstein, Bjørn E; Damsgaard, Mogens Trab

    2016-01-01

    OBJECTIVE: To investigate (i) associations between adolescents' frequency of breakfast and family functioning (close relations to parents, quality of family communication and family support) and (ii) if any observed associations between breakfast frequency and family functioning vary by sociodemo......OBJECTIVE: To investigate (i) associations between adolescents' frequency of breakfast and family functioning (close relations to parents, quality of family communication and family support) and (ii) if any observed associations between breakfast frequency and family functioning vary...... by sociodemographic factors. DESIGN: School-based cross-sectional study. Students completed a web-based questionnaire. Associations were estimated by multilevel multivariate logistic regression. SETTING: Danish arm of the Health Behaviour in School-aged Children study, 2014. SUBJECTS: Adolescents aged 13 and 15 years...... (n 3054) from a random sample of forty-one schools. RESULTS: Nearly one-quarter of the adolescents had low breakfast frequency. Low breakfast frequency was associated with low family functioning measured by three dimensions. The OR (95 % CI) of low breakfast frequency was 1·81 (1·40, 2...

  10. Frequency comb swept lasers.

    Science.gov (United States)

    Tsai, Tsung-Han; Zhou, Chao; Adler, Desmond C; Fujimoto, James G

    2009-11-09

    We demonstrate a frequency comb (FC) swept laser and a frequency comb Fourier domain mode locked (FC-FDML) laser for applications in optical coherence tomography (OCT). The fiber-based FC swept lasers operate at a sweep rate of 1kHz and 120kHz, respectively over a 135nm tuning range centered at 1310nm with average output powers of 50mW. A 25GHz free spectral range frequency comb filter in the swept lasers causes the lasers to generate a series of well defined frequency steps. The narrow bandwidth (0.015nm) of the frequency comb filter enables a approximately -1.2dB sensitivity roll off over approximately 3mm range, compared to conventional swept source and FDML lasers which have -10dB and -5dB roll offs, respectively. Measurements at very long ranges are possible with minimal sensitivity loss, however reflections from outside the principal measurement range of 0-3mm appear aliased back into the principal range. In addition, the frequency comb output from the lasers are equally spaced in frequency (linear in k-space). The filtered laser output can be used to self-clock the OCT interference signal sampling, enabling direct fast Fourier transformation of the fringe signals, without the need for fringe recalibration procedures. The design and operation principles of FC swept lasers are discussed and designs for short cavity lasers for OCT and interferometric measurement applications are proposed.

  11. Single frequency semiconductor lasers

    CERN Document Server

    Fang, Zujie; Chen, Gaoting; Qu, Ronghui

    2017-01-01

    This book systematically introduces the single frequency semiconductor laser, which is widely used in many vital advanced technologies, such as the laser cooling of atoms and atomic clock, high-precision measurements and spectroscopy, coherent optical communications, and advanced optical sensors. It presents both the fundamentals and characteristics of semiconductor lasers, including basic F-P structure and monolithic integrated structures; interprets laser noises and their measurements; and explains mechanisms and technologies relating to the main aspects of single frequency lasers, including external cavity lasers, frequency stabilization technologies, frequency sweeping, optical phase locked loops, and so on. It paints a clear, physical picture of related technologies and reviews new developments in the field as well. It will be a useful reference to graduate students, researchers, and engineers in the field.

  12. Hg(+) Frequency Standards

    Science.gov (United States)

    Prestage, John D.; Tjoelker, Robert L.; Maleki, Lute

    2000-01-01

    In this paper we review the development of Hg(+) microwave frequency standards for use in high reliability and continuous operation applications. In recent work we have demonstrated short-term frequency stability of 3 x 10(exp -14)/nu(sub tau) when a cryogenic oscillator of stability 2-3 x 10(exp 15) was used a the local oscillator. The trapped ion frequency standard employs a Hg-202 discharge lamp to optically pump the trapped Hg(+)-199 clock ions and a helium buffer gas to cool the ions to near room temperature. We describe a small Hg(+) ion trap based frequency standard with an extended linear ion trap (LITE) architecture which separates the optical state selection region from the clock resonance region. This separation allows the use of novel trap configurations in the resonance region since no optical pumping is carried out there. A method for measuring the size of an ion cloud inside a linear trap with a 12-rod trap is currently being investigated. At approx. 10(exp -12), the 2nd order Doppler shift for trapped mercury ion frequency standards is one of the largest frequency offsets and its measurement to the 1% level would represent an advance in insuring the very long-term stability of these standards to the 10(exp -14) or better level. Finally, we describe atomic clock comparison experiments that can probe for a time variation of the fine structure constant, alpha = e(exp 2)/2(pi)hc, at the level of 10(exp -20)/year as predicted in some Grand Unified String Theories.

  13. Frequency control modelling - basics

    DEFF Research Database (Denmark)

    Hansen, Anca Daniela; Sørensen, Poul Ejnar; Zeni, Lorenzo

    2016-01-01

    The purpose of this report is to provide an introduction on how the system balance in an island system can be maintained by controlling the frequency. The power balance differential equation, which is fundamental in understanding the effect on the system frequency of the unbalance between...... generation and consumption, is addressed. Basic topics on the main components of a generating unit, such generators, prime movers and governors are presented. A simple dynamic model for an island power system, containing realistic dynamic representations of generators, loads, prime movers, governors...

  14. Low frequency radioastronomy

    International Nuclear Information System (INIS)

    Zarka, Philippe; Cecconi, Baptiste; Tagger, Michel; Torchinsky, Steve; Picard, Philippe; Pezzani, Jacques; Cognard, Ismael; Boone, Frederic; Woan, Graham; Weber, Rodolphe; Gousset, Thierry; Lautridou, Pascal; Dallier, Richard

    2011-07-01

    Low frequency radioastronomy deals with the direct detection (below 100 MHz) and heterodyne detection (up to few GHz) of electromagnetic waves (phase and amplitude) followed by a time or spectral analysis. The 30. Goutelas school covered several aspects of radioastronomy involving various aspects of physics: non-thermal phenomena in plasmas and physics of magnetized plasmas, atomic and molecular physics, and particle physics. These proceedings comprise 17 lectures dealing with: 1 - Low-Frequency Radioastronomy Basics (P. Zarka); 2 - Radioastronomy Historical Highlights (S. A. Torchinsky); 3 - Antennas (P. Picard, J. Pezzani); 4 - Receptors (P. Picard, J. Pezzani); 5 - Pulsars chronometry: metrology in radioastronomy (I. Cognard); 6 - Interferometry as imaging technique (F. Boone); 7 - Radio propagation and scintillation (G. Woan); 8 - Square Kilometer Array (S. A. Torchinsky); 9 - Techniques against radio-electrical interferences in low-frequency radioastronomy (R. Weber); 10 - Introduction to poly-phase filtering (R. Weber); 11 - Three decades of Jupiter's radio-emission studies: from the Nancay deca-meter network to LOFAR (P. Zarka); 12 - Atmospheric showers and their radio counterpart (T. Gousset); 13 - From cosmic rays radio-detection to pulse radioastronomy (P. Lautridou, R. Dallier); 14 - The CODALEMA project (R. Dallier, P. Lautridou); 15 - Space-based radio measurements: Gonio-polarimetry (B. Cecconi); 16 - Radio astronomy from space (G. Woan); 17 - LOFAR: the Low Frequency Array and the French FLOW consortium (M. Tagger, P. Zarka)

  15. Frequency and turmoil

    African Journals Online (AJOL)

    level of popular unrest focused on 'service delivery protests', but in recent years the broader conception of ... Drawing on the Centre for Social Change's archive of media reports, the largest database of its kind, and by comparing its data with .... impact on frequencies. The variation evident in the table is not accidental but is ...

  16. Radio Frequency Identification

    Indian Academy of Sciences (India)

    Radio Frequency Identification (RFID) has been around sinceearly 2000. Its use has currently become commonplace as thecost of RFID tags has rapidly decreased. RFID tags have alsobecome more 'intelligent' with the incorporation of processorsand sensors in them. They are widely used now in manyinnovative ways.

  17. Radio Frequency Identification

    Indian Academy of Sciences (India)

    collection and accounting daily, London commuter system uses the data gathered by the central computer to optimize scheduling of trains and buses. With millions of cards in use, the cost of an oyster card with an RFID tag is amortized by the fare collected. The system is a near-field system using low-frequency tags. 3.

  18. High frequency electromagnetic dosimetry

    CERN Document Server

    Sánchez-Hernández, David A

    2009-01-01

    Along with the growth of RF and microwave technology applications, there is a mounting concern about the possible adverse effects over human health from electromagnetic radiation. Addressing this issue and putting it into perspective, this groundbreaking resource provides critical details on the latest advances in high frequency electromagnetic dosimetry.

  19. Metamaterial for Radar Frequencies

    Science.gov (United States)

    2012-09-01

    capacitive coupling with adjacent patches, as shown in Figure 3. The via provides inductance to ground. Figure 3. (a) Planar LH distributed periodic...After [20]). The capacitance in the structure balances out the inductance present when the cylinder is placed in a square array. The metallic... RADAR FREQUENCIES by Szu Hau Tan September 2012 Thesis Advisor: David C. Jenn Second Reader: James Calusdian

  20. The effect of real and virtual visual cues on walking in Parkinson's disease.

    Science.gov (United States)

    Griffin, H J; Greenlaw, R; Limousin, P; Bhatia, K; Quinn, N P; Jahanshahi, M

    2011-06-01

    Patients with Parkinson's disease (PwPD) have a slow, shuffling gait, marked by sporadic freezing of gait (FoG) during which effective stepping ceases temporarily. As these gait problems are not commonly improved by medical and surgical treatments, alternative approaches to manage these problems have been adopted. The aim of this study was to evaluate the effect of real and virtual visual cues on walking in PD. We assessed 26 mid-stage PwPD, on and off medication, on a laboratory-based walking task which simulated real world challenges by incorporating FoG triggers and using appropriate placebo conditions. Cueing interventions were presented via virtual reality glasses (VRG rhythmic, visual flow and static placebo cues), and as transverse lines (TL) on the walkway. Objective measures of gait (task completion time; velocity, cadence, stride length; FoG frequency) and self-rated fear of falling (FoF) were recorded. Cueing intervention affected task completion time only off medication. Whereas placebo VRG cues provided no improvement in walking, visual flow VRG cues marginally reduced the task completion time. TL on the floor elicited more substantial improvements in gait with reduced cadence, increased stride length and reduced FoG frequency. VRG rhythmic cueing impaired overall walking. Notably, a final no-intervention condition yielded quicker task completion, greater walking velocity, increased stride length and less frequent FoG. Although the VRG produced modest improvements only in the visual flow condition, their flexibility is an advantage. These results endorse the use of TL and justify further testing and customisation of VRG cues for individual PwPD.

  1. Acute Effects of Plyometric Intervention—Performance Improvement and Related Changes in Sprinting Gait Variability.

    Science.gov (United States)

    Maćkała, Krzysztof; Fostiak, Marek

    2015-07-01

    The purpose of this study was to examine the effect of a short high-intensity plyometric program on the improvement of explosive power of lower extremities and sprint performance as well as changes in sprinting stride variability in male sprinters. Fourteen healthy male sprinters (mean ± SD: age: 18.07 ± 0.73 years, body mass: 73 ± 9.14 kg, height: 180.57 ± 8.16 cm, and best 100 m: 10.89 ± 0.23) participated in the experiment. The experimental protocol included vertical jumping such as squat jump, countermovement jump, and horizontal jumps; standing long jump and standing triple jumps to assess lower-body power, maximal running velocity; a 20-m flying start sprint that evaluated variability of 10 running steps and 60-m starting block sprint. All analyzed parameters were obtained using the new technology of OptoJump-Microgate (OptoJump, Italy). The short-term plyometric training program significantly increased the explosive power of lower extremities, both vertical and horizontal jumping improvement. However, the vertical jumps increased much more than the horizontal. The 20-m improvements were derived from an increase of stride frequency from 4.31 to 4.39 Hz because of a decrease of ground contact time from 138 to 133 milliseconds. This did not translate into step length changes. Therefore, the significantly increased frequency of stride (1.8%), which is a specific expression of ground contact time reduction during support phase, resulted in an increase of speed. The training volume of 2 weeks (with 6 sessions) using high-intensity (between 180 and 250 jumps per session) plyometric exercises can be recommended as the short-term strategy that will optimize one's probability of reaching strong improvements in explosive power and sprint velocity performance.

  2. Cities lead on climate change

    Science.gov (United States)

    Pancost, Richard D.

    2016-04-01

    The need to mitigate climate change opens up a key role for cities. Bristol's year as a Green Capital led to great strides forward, but it also revealed that a creative and determined partnership across cultural divides will be necessary.

  3. Zhena Toni Blera rabotala naturshtshitsei

    Index Scriptorium Estoniae

    2006-01-01

    Suurbritannia peaministri Tony Blairi abikaasa Cherie Booth poseeris oma noorusaastatel inglise kunstniku Euan Uglow' maali jaoks "Striding Nude, Blue Dress". Maal jäi lõpetamata. Asub Marlborough Fine Art Trust muuseumis

  4. Greening the Golden Gate National Recreation Area

    Science.gov (United States)

    The Golden Gate National Recreation Area was recognized a 2016 Federal Green Challenge Award for making significant strides to reduce its carbon footprint with the goal of becoming a carbon neutral park.

  5. What we do | Page 128 | IDRC - International Development ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Advancing Evidence Based Policymaking and Regulation to Ensure Greater Participation in ICTs (LIRNEasia Phase II). Significant strides have been made in closing the digital divide in Asia, mainly due to the proliferation of mobile telephones. Asia. PROJECT ...

  6. Residual attentional capacity amongst young and elderly during dual and triple task walking

    DEFF Research Database (Denmark)

    Læssøe, Uffe; Hoeck, Hans C.; Simonsen, Ole

    2008-01-01

    to the cognitive task the elderly increased their temporal stride-to-stride variability by 39% in the walking task and by 57% in the combined motor task. These increases were significantly larger than observed for the young. Equivalent decreases in trunk acceleration autocorrelation coefficients and gait speed...... in the study. The participants walked along a figure-of-eight track at a self-selected speed. The effect of introducing a concurrent cognitive task and a concurrent functional motor task was evaluated. Stride-to-stride variability was measured by heel contacts and by trunk accelerometry. In response...... were found. A combination of sufficiently challenging motor tasks and concurrent cognitive tasks can reveal signs of limited residual attentional capacity during walking amongst the elderly....

  7. A synergy perspective on gait – over-ground vs. treadmill walking

    DEFF Research Database (Denmark)

    Læssøe, Uffe; Madeleine, Pascal

    INTRODUCTION: Increased stride-to-stride time variability is reported among elderly fallers and various patient groups [1]. Variability is therefore often regarded as an indicator of gait deficits. However, movement variability is also a general and natural phenomenon. A synergy perspective...... on movements has proposed that elemental and performance variables may represent good and bad components of variability [2]. We suggest that the gait pattern can be regarded as a movement synergy in which medio-lateral deviation in one stride can be corrected during the next stride (the elemental variables......). Such corrections ensure a straight gait path (the performance variable). AIM: The aim of this study was to apply a synergy approach to gait analysis by comparing over-ground and treadmill walking. The treadmill was hypothesized to demand a less variable walking path resulting in a larger good/bad variability ratio...

  8. Taking flight with sensing equipment will deliver benefits across MDOT : research spotlight.

    Science.gov (United States)

    2015-04-01

    Recent strides in technology have opened the doors for using unmanned : aerial vehicles (UAVs, sometimes called drones) throughout MDOT. An : extensive study on the viability of UAVs instrumented with remote : sensors demonstrated a wide range of cos...

  9. What Are the Caregiver's Rights?

    Science.gov (United States)

    ... heart Lifestyle + Risk Reduction Caregiving What Are the Caregiver’s Rights? Caring for someone you love after a ... strides will be made toward aiding and supporting caregivers. How do I assert my rights? Put these ...

  10. Parkinson's Disease Videos

    Medline Plus

    Full Text Available ... Any Tips to Use for Freezing? How Does Speech Therapy Help Parkinson's Patients? CareMAP: Is a Care ... Parkinson's Mid-Stride: A Treatment Guide to Parkinson's Speech and Swallowing Psychosis: A Mind Guide to Parkinson's ...

  11. Integrated urban systems modeling : designing a seamless, comprehensive approach to transportation planning.

    Science.gov (United States)

    2009-01-01

    Metropolitan planning agencies face increasingly complex issues in modeling interactions between the built environment and multimodal transportation systems. Although great strides have been made in simulating land use, travel demand, and traffic flo...

  12. Parkinson's Disease Videos

    Medline Plus

    Full Text Available ... the Helpline: What Is the Helpline? How Does Speech Therapy Help Parkinson's Patients? CareMAP: El Vestirse Caregiver ... Parkinson's Mid-Stride: A Treatment Guide to Parkinson's Speech and Swallowing Psychosis: A Mind Guide to Parkinson's ...

  13. Towards an internet of things tangible program environment supported by indigenous African artefacts

    CSIR Research Space (South Africa)

    Smith, Andrew C

    2016-11-01

    Full Text Available According to its advocates, the Internet of Things holds great promise. Great strides have been made to address its security and standardise communication protocols for data exchange in this potentially unlimited network of connected things. However...

  14. A comparison of crashes and fatalities in Texas by age group : selected cities in Texas.

    Science.gov (United States)

    2012-10-01

    In recent decades, great strides have been made to lower the number of accidents that occur on Texas roadways through graduated drivers licensing programs, messages against texting and driving, and discouraging drunk driving. Statistics show that you...

  15. Fossil Footprints: How Fast Was That Dinosaur Moving?

    Science.gov (United States)

    Caton, Randall; Otts, Charlotte

    1999-01-01

    Describes an activity in which students construct relationships between their leg lengths, stride lengths, and movements in order to estimate the speeds of the dinosaurs that made various fossilized tracks. (WRM)

  16. Brazil's Difficult Road to Greatness

    National Research Council Canada - National Science Library

    Wolfe, David C

    2008-01-01

    Brazil is an emerging country that has made important strides in consolidating its democracy, constructing a diversified and financially sound economy, and enhancing its diplomatic participation on the world stage...

  17. Economic effects of access management techniques in North Carolina.

    Science.gov (United States)

    2010-12-21

    The NCDOT has made significant strides to reduce collisions and increase capacity along : strategic highway corridors across the state. Efforts have led to the implementation of many : different access management techniques along corridors, such as i...

  18. On Cell–Matrix Interactions in Mammary Gland Development and Breast Cancer

    OpenAIRE

    Talhouk, Rabih

    2012-01-01

    Remarkable strides have been made in understanding the role of the extracellular matrix in mammary gland biology. But future efforts should employ a more physiologically relevant model system (i.e., a non-culture-based system).

  19. Pancreatic Neuroendocrine Tumors (PNETs)

    Science.gov (United States)

    ... Stories Our signature PurpleStride run/walk events raise spirits, awareness and funds in communities nationwide. FIND YOUR ... two main pancreatic hormones. Insulin lowers blood sugar levels, while glucagon raises blood sugar levels. Together, these ...

  20. Parkinson's Disease Videos

    Medline Plus

    Full Text Available ... of Treatment Is Initiated After Diagnosis? How Does Speech Therapy Help Parkinson's Patients? CareMAP: When Is It ... Parkinson's Mid-Stride: A Treatment Guide to Parkinson's Speech and Swallowing Psychosis: A Mind Guide to Parkinson's ...

  1. Japan-U.S. Relations: Issues for Congress

    National Research Council Canada - National Science Library

    Chanlett-Avery, Emma; Manyin, Mark E; Cooper, William H

    2006-01-01

    .... The Bush Administration has made significant strides in its goals of broadening U.S.-Japan strategic cooperation and encouraging Japan to assume a more active international role. In 2005 the U.S...

  2. ARTI. ~.~E•,y

    African Journals Online (AJOL)

    power, and the mobility of the new weapons made more mobile tactics possible. Scientific and tech- nological progress made great strides and enabled the contestants to overcome many of the natural obstacles that had hindered earlier armies.

  3. A critical needs assessment for collaborative ecotourism development linked to protected areas in Cross River State, Nigeria

    Science.gov (United States)

    Jeffrey J. Brooks; John Neary; Blessing E. Asuquo

    2007-01-01

    Nigeria has abundant natural resources, and the nation, working with its partners over the years, has made large strides toward conservation of this natural wealth, but the future of Nigeria's natural resources remains uncertain.

  4. How Do You Feel?

    DEFF Research Database (Denmark)

    Rosfort, René; Stanghellini, Giovanni

    2014-01-01

    This article argues for the importance of investigating emotions in psychiatry. In a time dominated by striding naturalistic explanations of mental illness, phenomenological psychopathology provides a crucial investigation into the subjective aspect of the disordered mind. Emotional phenomena are...

  5. Airway Clearance Techniques (ACTs)

    Medline Plus

    Full Text Available ... Sponsor a Participant CF Climb CF Cycle for Life Great Strides Xtreme Hike Participate In addition to working for a cure, the CF Foundation supports programs and policies to improve the lives of ...

  6. THE EMERGENCE OF ECOLOGICAL ENGINEERING AS A DISCIPLINE

    Science.gov (United States)

    Pioneering efforts in the field of ecological engineering research and practice have proven to be tremendous strides toward establishing a new engineering discipline with a science base in ecology. Case studies, demonstrations and applications pertaining to restoration, rehabili...

  7. Sidewalk Survey Implementation for the Southeast Region

    Science.gov (United States)

    2017-06-01

    With funding from GDOT and STRIDE, the team deployed the Online Sidewalk Assessment Survey to gather input on local sidewalk repair and maintenance preferences across a variety of community types in the southeast. The team targeted four major cities ...

  8. Airway Clearance Techniques (ACTs)

    Medline Plus

    Full Text Available ... in a fundraising event, or volunteering with your local chapter. DONATE YOUR TIME FIND A CLINICAL TRIAL FIND A LOCAL CHAPTER Great Strides Participate in an Event Conference ...

  9. Parkinson's Disease Videos

    Medline Plus

    Full Text Available ... the Helpline: What Is the Helpline? How Does Speech Therapy Help Parkinson's Patients? When and What Type ... Parkinson's Mid-Stride: A Treatment Guide to Parkinson's Speech and Swallowing Psychosis: A Mind Guide to Parkinson's ...

  10. Predoctoral Training Program in Breast Cancer Research

    National Research Council Canada - National Science Library

    Stern, David F

    2004-01-01

    .... This means that research on breast cancer has finally advanced to the stage where a concentrated effort in translational research will yield great strides in detection, diagnosis, and treatment...

  11. Airway Clearance Techniques (ACTs)

    Medline Plus

    Full Text Available ... Awards CF BASIC RESEARCH CENTERS North American CF Conference 2017 NACFC Carolyn and C Richard Mattingly Leadership ... LOCAL CHAPTER Great Strides Participate in an Event Conference Livestreams Fundraising Events Virtual Events RAISE CF AWARENESS ...

  12. Impact of Nigerian Institute For Oil Palm Research (N.I.F.O.R.) on oil ...

    African Journals Online (AJOL)

    NIFOR) on oil palm industry in Nigeria. It interfaces of achievements and developmental strides of the Institute on oil palm industry in Nigeria from its was establishment during colonial period as Oil Palm Research Station (OPRS.) in 1939 ...

  13. Food frequency questionnaires.

    Science.gov (United States)

    Pérez Rodrigo, Carmen; Aranceta, Javier; Salvador, Gemma; Varela-Moreiras, Gregorio

    2015-02-26

    Food Frequency Questionnaires are dietary assessment tools widely used in epidemiological studies investigating the relationship between dietary intake and disease or risk factors since the early '90s. The three main components of these questionnaires are the list of foods, frequency of consumption and the portion size consumed. The food list should reflect the food habits of the study population at the time the data is collected. The frequency of consumption may be asked by open ended questions or by presenting frequency categories. Qualitative Food Frequency Questionnaires do not ask about the consumed portions; semi-quantitative include standard portions and quantitative questionnaires ask respondents to estimate the portion size consumed either in household measures or grams. The latter implies a greater participant burden. Some versions include only close-ended questions in a standardized format, while others add an open section with questions about some specific food habits and practices and admit additions to the food list for foods and beverages consumed which are not included. The method can be self-administered, on paper or web-based, or interview administered either face-to-face or by telephone. Due to the standard format, especially closed-ended versions, and method of administration, FFQs are highly cost-effective thus encouraging its widespread use in large scale epidemiological cohort studies and also in other study designs. Coding and processing data collected is also less costly and requires less nutrition expertise compared to other dietary intake assessment methods. However, the main limitations are systematic errors and biases in estimates. Important efforts are being developed to improve the quality of the information. It has been recommended the use of FFQs with other methods thus enabling the adjustments required. Copyright AULA MEDICA EDICIONES 2015. Published by AULA MEDICA. All rights reserved.

  14. Walking behaviour of healthy elderly: attention should be paid

    Directory of Open Access Journals (Sweden)

    Schmidt André

    2010-10-01

    Full Text Available Abstract Background Previous studies have reported an association between executive function (EF and measures of gait, particularly among older adults. This study examined the relationship between specific components of executive functions and the relative dual task costs of gait (DTC in community-dwelling non-demented older adults, aged 65 years and older. Methods Temporal (stride time, stride velocity and spatial (stride length gait characteristics were measured using a GAITRite®-System among 62 healthy community dwelling older adults while walking with and without backward counting (BC at preferred and fast walking speeds. Specific executive functions divided attention, memory and inhibition were assessed using the Test for Attentional Performance (TAP. Other measures included Mini-Mental State Examination (MMSE, amount of daily medications taken, educational level and sociodemographic characteristics. Adjusted and unadjusted multivariable linear regression models were developed to assess the relations between variables. Results High relative DTC for stride time, stride velocity and stride length were associated with divided attention at fast walking speed. High relative DTC for stride time was associated with divided attention at preferred walking speed. The association between high DTC of stride length and memory was less robust and only observable at preferred walking speed. None of the gait measures was associated with inhibition. Conclusions Spatial and temporal dual task cost characteristics of gait are especially associated with divided attention in older adults. The results showed that the associated DTC differ by executive function and the nature of the task (preferred versus fast walking. Further research is warranted to determine whether improvement in divided attention translates to better performance on selected complex walking tasks.

  15. The Department of Homeland Security’s Pursuit of Data-Driven Decision Making

    Science.gov (United States)

    2015-12-01

    strategies as the Department makes strides towards removing itself from the GAO’s classification of DHS as “high- risk ”—a categorization due in part to...Department makes strides towards removing itself from the GAO’s classification of DHS as “high- risk ”—a categorization due in part to DHS’s inability to...91 C. POST ERP STRATEGY – TWO PATHS FORWARD .......................94 1. “Federal Shared Service Provider” Model

  16. Constraint-Led Changes in Internal Variability in Running

    OpenAIRE

    Haudum, Anita; Birklbauer, Jürgen; Kröll, Josef; Müller, Erich

    2012-01-01

    We investigated the effect of a one-time application of elastic constraints on movement-inherent variability during treadmill running. Eleven males ran two 35-min intervals while surface EMG was measured. In one of two 35-min intervals, after 10 min of running without tubes, elastic tubes (between hip and heels) were attached, followed by another 5 min of running without tubes. To assess variability, stride-to-stride iEMG variability was calculated. Significant increases in variability (36 % ...

  17. Radio frequency ion source

    CERN Document Server

    Shen Guan Ren; Gao Fu; LiuNaiYi

    2001-01-01

    The study on Radio Frequency Ion Source is mainly introduced, which is used for CIAE 600kV ns Pulse Neutron Generator; and obtained result is also presented. The RF ion source consists of a diameter phi 25 mm, length 200 mm, coefficient of expansion =3.5 mA, beam current on target >=1.5 mA, beam spot =100 h.

  18. Qigong exercise may improve sleep quality and gait performance in Parkinson's disease: a pilot study.

    Science.gov (United States)

    Wassom, Derek J; Lyons, Kelly E; Pahwa, Rajesh; Liu, Wen

    2015-01-01

    Parkinson's disease (PD) involves a variety of motor and non-motor symptoms, several of which, including gait abnormalities and sleep disorders, are generally not adequately managed with standard therapy. This study aimed to determine the impact of Qigong as a potential complementary therapy in the management of gait and sleep-related symptoms in PD. Seven subjects (aged 66.9 ± 8.1 years) with PD participated in a six-week Qigong exercise intervention. Pre- and post-intervention testing was performed to assess sleep quality, cognitive function, fatigue, quality of life, gait performance (stride time, stride length, double support time, and velocity), and gait variability (stride time and length variability). Following Qigong, subjects showed improvement in some aspects of sleep quality. Fatigue remained unchanged. Gait function was improved by a significant reduction of stride time and a slight increase in stride length. Together these changes resulted in significant improvements to gait velocity. In addition, time spent in double limb support was reduced following the intervention. Overall gait variability improved significantly, particularly in the reduction of stride time variability. These results suggest that Qigong may provide benefit for gait performance and sleep quality in PD patients. However, larger, controlled studies are required to determine the immediate and long-term benefits of Qigong for PD sleep and gait problems as well as the impact on other aspects of the disease.

  19. Gait unsteadiness and fall risk in two affective disorders: a preliminary study

    Directory of Open Access Journals (Sweden)

    Peng Chung-Kang

    2004-11-01

    Full Text Available Abstract Background In older adults, depression has been associated with increased fall risk, but the reasons for this link are not fully clear. Given parallels between major depression and Parkinson's disease, we hypothesized that major depression and related affective disorders would be associated with impairment in the ability to regulate the stride-to-stride fluctuations in gait cycle timing. Methods We measured stride-to-stride fluctuations of patients with two forms of mood disorders, unipolar major depressive disorder (MDD and bipolar disorder, and compared their gait to that of a healthy control group. The primary outcomes were two measures of gait unsteadiness that have been associated with fall risk: stride time variability and swing time variability. Results Compared to the control group, the two patient groups tended to walk more slowly and with decreased swing time and increased stride time. However, none of these differences was statistically significant. Compared to the control group, swing time variability was significantly larger in the subjects with bipolar disorder (p Conclusions Patients with MDD and patients with bipolar disorder display gait unsteadiness. This perturbation in gait may provide a mechanistic link connecting depression and falls. The present findings also suggest the possibility that measurement of variability of gait may provide a readily quantifiable objective approach to monitoring depression and related affective disorders.

  20. Effects of a minimalist shoe on running economy and 5-km running performance.

    Science.gov (United States)

    Fuller, Joel T; Thewlis, Dominic; Tsiros, Margarita D; Brown, Nicholas A T; Buckley, Jonathan D

    2016-09-01

    The purpose of this study was to determine if minimalist shoes improve time trial performance of trained distance runners and if changes in running economy, shoe mass, stride length, stride rate and footfall pattern were related to any difference in performance. Twenty-six trained runners performed three 6-min sub-maximal treadmill runs at 11, 13 and 15 km·h(-1) in minimalist and conventional shoes while running economy, stride length, stride rate and footfall pattern were assessed. They then performed a 5-km time trial. In the minimalist shoe, runners completed the trial in less time (effect size 0.20 ± 0.12), were more economical during sub-maximal running (effect size 0.33 ± 0.14) and decreased stride length (effect size 0.22 ± 0.10) and increased stride rate (effect size 0.22 ± 0.11). All but one runner ran with a rearfoot footfall in the minimalist shoe. Improvements in time trial performance were associated with improvements in running economy at 15 km·h(-1) (r = 0.58), with 79% of the improved economy accounted for by reduced shoe mass (P economy and 5-km running performance.

  1. Mobile inertial sensor based gait analysis: Validity and reliability of spatiotemporal gait characteristics in healthy seniors.

    Science.gov (United States)

    Donath, Lars; Faude, Oliver; Lichtenstein, Eric; Pagenstert, Geert; Nüesch, Corina; Mündermann, Annegret

    2016-09-01

    Gait analysis is commonly used to identify gait changes and fall risk in clinical populations and seniors. Body-worn inertial sensor based gait analyses provide a feasible alternative to optometric and pressure based measurements of spatiotemporal gait characteristics. We assessed validity and relative and absolute reliability of a body-worn inertial sensor system (RehaGait(®)) for measuring spatiotemporal gait characteristics compared to a standard stationary treadmill (Zebris(®)). Spatiotemporal gait parameters (walking speed, stride length, cadence and stride time) were collected for 24 healthy seniors (age: 75.3±6.7 years) tested on 2 days (1 week apart) simultaneously using the sensor based system and instrumented treadmill. Each participant completed walking tests (200 strides) at different walking speeds and slopes. The difference between the RehaGait(®) system and the treadmill was trivial (Cohen's dgait characteristics (cadence and stride time; ICC: 0.99-1.00) and moderate for stride length (ICC: 0.73-0.89). Both devices had excellent day-to-day reliability for all gait parameters (ICC: 0.82-0.99) except for stride length at slow speed (ICC: 0.74). The RehaGait(®) is a valid and reliable tool for assessing spatiotemporal gait parameters for treadmill walking at different speeds and slopes. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. Agreement between the GAITRite walkway system and a stopwatch-footfall count method for measurement of temporal and spatial gait parameters.

    Science.gov (United States)

    Youdas, James W; Hollman, John H; Aalbers, Monica J; Ahrenholz, Holly N; Aten, Rebecca A; Cremers, Joseph J

    2006-12-01

    To determine the agreement for measurements of stride length, cadence, and walking speed obtained from the GAITRite system and the stopwatch-footfall count technique. Criterion standard. Research laboratory in a physical therapy education program. Forty healthy volunteers (13 men, 27 women) without lower-extremity injury. Participants walked across a GAITRite mat with embedded pressure sensors at their self-selected walking speed. Simultaneously, an examiner used a stopwatch to record the elapsed time necessary to cross the mat and counted the number of complete footfalls. Walking speed, cadence, and stride-length measures were compared between the GAITRite system and the stopwatch-footfall count technique. Correlation coefficients comparing both systems were .97 for walking speed, .75 for cadence, and .85 for stride length. Ninety-five percent of the time we would expect the between-methods differences to range between .09 and -.05m/s for walking speed, between -1.5 and -24.3 steps/min for cadence, and between .01 and .37m for stride length. This study shows that the GAITRite and stopwatch-footfall count methods lack clinically acceptable agreement for the measurements of cadence and stride length in a group of healthy volunteers walking at their self-selected speeds. Clinicians who require precise measurement of cadence and stride length should consider using the GAITRite system instead of the stopwatch-footfall count technique.

  3. A quantitative analysis of gait patterns in vestibular neuritis patients using gyroscope sensor and a continuous walking protocol.

    Science.gov (United States)

    Kim, Soo Chan; Kim, Joo Yeon; Lee, Hwan Nyeong; Lee, Hwan Ho; Kwon, Jae Hwan; Kim, Nam Beom; Kim, Mi Joo; Hwang, Jong Hyun; Han, Gyu Cheol

    2014-04-11

    Locomotion involves an integration of vision, proprioception, and vestibular information. The parieto-insular vestibular cortex is known to affect the supra-spinal rhythm generators, and the vestibular system regulates anti-gravity muscle tone of the lower leg in the same side to maintain an upright posture through the extra-pyramidal track. To demonstrate the relationship between locomotion and vestibular function, we evaluated the differences in gait patterns between vestibular neuritis (VN) patients and normal subjects using a gyroscope sensor and long-way walking protocol. Gyroscope sensors were attached to both shanks of healthy controls (n=10) and age-matched VN patients (n = 10). We then asked the participants to walk 88.8 m along a corridor. Through the summation of gait cycle data, we measured gait frequency (Hz), normalized angular velocity (NAV) of each axis for legs, maximum and minimum NAV, up-slope and down-slope of NAV in swing phase, stride-swing-stance time (s), and stance to stride ratio (%). The most dominant walking frequency in the VN group was not different compared to normal control. The NAVs of z-axis (pitch motion) were significantly larger than the others (x-, y-axis) and the values in VN patients tended to decrease in both legs and the difference of NAV between both group was significant in the ipsi-lesion side in the VN group only (p=0.03). Additionally, the gait velocity of these individuals was decreased relatively to controls (1.11 ± 0.120 and 0.84 ± 0.061 m/s in control and VN group respectively, p<0.01), which seems to be related to the significantly increased stance and stride time of the ipsi-lesion side. Moreover, in the VN group, the maximum NAV of the lesion side was less, and the minimum one was higher than control group. Furthermore, the down-slope and up-slope of NAV decreased on the impaired side. The walking pattern of VN patients was highly phase-dependent, and NAV of pitch motion was significantly decreased in the ipsi

  4. Resonance frequency analysis

    Directory of Open Access Journals (Sweden)

    Rajiv K Gupta

    2011-01-01

    Full Text Available Initial stability at the placement and development of osseointegration are two major issues for implant survival. Implant stability is a mechanical phenomenon which is related to the local bone quality and quantity, type of implant, and placement technique used. The application of a simple, clinically applicable, non-invasive test to assess implant stability and osseointegration is considered highly desirable. Resonance frequency analysis (RFA is one of such techniques which is most frequently used now days. The aim of this paper was to review and analyze critically the current available literature in the field of RFA, and to also discuss based on scientific evidence, the prognostic value of RFA to detect implants at risk of failure. A search was made using the PubMed database to find all the literature published on "Resonance frequency analysis for implant stability" till date. Articles discussed in vivo or in vitro studies comparing RFA with other methods of implant stability measurement and articles discussing its reliability were thoroughly reviewed and discussed. A limited number of clinical reports were found. Various studies have demonstrated the feasibility and predictability of the technique. However, most of these articles are based on retrospective data or uncontrolled cases. Randomized, prospective, parallel-armed longitudinal human trials are based on short-term results and long-term follow up are still scarce in this field. Nonetheless, from available literature, it may be concluded that RFA technique evaluates implant stability as a function of stiffness of the implant bone interface and is influenced by factors such as bone type, exposed implant height above the alveolar crest. Resonance frequency analysis could serve as a non-invasive diagnostic tool for detecting the implant stability of dental implants during the healing stages and in subsequent routine follow up care after treatment. Future studies, preferably randomized

  5. Radio frequency pulse compression

    International Nuclear Information System (INIS)

    Farkas, Z.D.

    1988-12-01

    High gradients require peak powers. One possible way to generate high peak powers is to generate a relatively long pulse at a relatively low power and compress it into a shorter pulse with higher peak power. It is possible to compress before dc to rf conversion as is done for the relativistic klystron or after dc to rf conversion as is done with SLED. In this note only radio frequency pulse compression (RFPC) is considered. Three methods of RFPC will be discussed: SLED, BEC, and REC. 3 refs., 8 figs., 1 tab

  6. Three-dimensional kinematics of capuchin monkey bipedalism.

    Science.gov (United States)

    Demes, Brigitte

    2011-05-01

    Capuchin monkeys are known to use bipedalism when transporting food items and tools. The bipedal gait of two capuchin monkeys in the laboratory was studied with three-dimensional kinematics. Capuchins progress bipedally with a bent-hip, bent-knee gait. The knee collapses into flexion during stance and the hip drops in height. The knee is also highly flexed during swing to allow the foot which is plantarflexed to clear the ground. The forefoot makes first contact at touchdown. Stride frequency is high, and stride length and limb excursion low. Hind limb retraction is limited, presumably to reduce the pitch moment of the forward-leaning trunk. Unlike human bipedalism, the bipedal gait of capuchins is not a vaulting gait, and energy recovery from pendulum-like exchanges is unlikely. It extends into speeds at which humans and other animals run, but without a human-like gait transition. In this respect it resembles avian bipedal gaits. It remains to be tested whether energy is recovered through cyclic elastic storage and release as in bipedal birds at higher speeds. Capuchin bipedalism has many features in common with the facultative bipedalism of other primates which is further evidence for restrictions on a fully upright striding gait in primates that transition to bipedalism. It differs from the facultative bipedalism of other primates in the lack of an extended double-support phase and short aerial phases at higher speeds that make it a run by kinematic definition. This demonstrates that facultative bipedalism of quadrupedal primates need not necessarily be a walking gait. Copyright © 2011 Wiley-Liss, Inc.

  7. The biomechanics of race walking: literature overview and new insights.

    Science.gov (United States)

    Pavei, Gaspare; Cazzola, Dario; La Torre, Antonio; Minetti, Alberto E

    2014-01-01

    This review aims to provide both researchers and coaches with a comprehensive overview of race walking biomechanics and to point out new viable route for future analyses. The examined literature has been divided into three categories according to the method of analysis: kinematics, ground reaction forces and joint power/efficiency. From an overall view, race walking athletes seem to adhere to the 'straightened knee' rule, but at race speed they do not observe the 'no-flight time' rule. The coach-oriented analysis highlights that stride length (SL) is more important than stride frequency (SF) for increasing speed and it is mainly obtained by ankle and hip joint power. Moreover, kinematic differences (SF, SL and flight time) between male and female athletes were shown. Also, we found that the maximal speed prediction according to dynamic similarity theory with walking (Froude number) is not applicable as the 3D trajectory of the body centre of mass does not follow an arc of circumference as in walking. The analysed literature shows some shortcomings: (1) the data collection is often unreliable because of the mixture of gender and performance level and (2) the analysis has sometimes been performed on a limited number of strides and speeds. These limitations lead to a scattered and incomplete gait description and a biased application of the results. The research strategy adopted so far is promising but further rigorous analyses need to be approached to obtain a fully comprehensive picture of race walking and to provide coaches with consistent results and reference values.

  8. Identification of subgroups among fibromyalgia patients

    Directory of Open Access Journals (Sweden)

    D. Chaleil

    2012-09-01

    Full Text Available This paper presents some hypotheses concerning the identification of homogeneous subgroups among fibromyalgia (FM patients in order to improve the management of the disease. It also reviews the available literature about this subject. Three methods for subgrouping are discussed according to clinical features, biomarkers, and gait analysis. Clinical subgrouping based on cluster analysis has been used for the identification of homogeneous subgroups of patients and, more recently, homogeneous clinical features. So far, longitudinal studies using clinical subgroups to direct treatment and predict outcome are still required. Biomarkers in FM, which is a neurobiological disease, are of promising interest, nevertheless currently, none of them can be used to subgroup FM patients. Due to the fact that cortical and subcortical mechanisms of gait control share some cognitive functions which are involved in FM, gait markers have been proposed to evaluate and to subgroup FM patients, in clinical settings. Three out of 4 core FM symptoms are linked to gait markers. Kinesia measured by means of cranio-caudal power is correlated to pain, and could be proposed to assess pain behavior (kinesiophobia. Stride frequency, which is linked to physical component, allows the identification of a hyperkinetic subgroup. Moreover, SF has been correlated to fatigue during the 6 minute walking test. Stride regularity, which expresses the unsteadiness of gait, is correlated to cognitive dysfunction in FM. Decreased stride regularity allows the recognition of a homogeneous subgroup characterized by an increased anxiety and depression, and decreased cognitive functions. These results need further studies to be validated and so used in the daily clinical practice.

  9. Identification of subgroups among fibromyalgia patients.

    Science.gov (United States)

    Auvinet, B; Chaleil, D

    2012-09-28

    This paper presents some hypotheses concerning the identification of homogeneous subgroups among fibromyalgia (FM) patients in order to improve the management of the disease. It also reviews the available literature about this subject. Three methods for subgrouping are discussed according to clinical features, biomarkers, and gait analysis. Clinical subgrouping based on cluster analysis has been used for the identification of homogeneous subgroups of patients and, more recently, homogeneous clinical features. So far, longitudinal studies using clinical subgroups to direct treatment and predict outcome are still required. Biomarkers in FM, which is a neurobiological disease, are of promising interest, nevertheless currently, none of them can be used to subgroup FM patients. Due to the fact that cortical and subcortical mechanisms of gait control share some cognitive functions which are involved in FM, gait markers have been proposed to evaluate and to subgroup FM patients, in clinical settings. Three out of 4 core FM symptoms are linked to gait markers. Kinesia measured by means of cranio-caudal power is correlated to pain, and could be proposed to assess pain behavior (kinesiophobia). Stride frequency, which is linked to physical component, allows the identification of a hyperkinetic subgroup. Moreover, SF has been correlated to fatigue during the 6 minute walking test. Stride regularity, which expresses the unsteadiness of gait, is correlated to cognitive dysfunction in FM. Decreased stride regularity allows the recognition of a homogeneous subgroup characterized by an increased anxiety and depression, and decreased cognitive functions. These results need further studies to be validated and so used in the daily clinical practice.

  10. Behavioral estimates of human frequency selectivity at low frequencies

    DEFF Research Database (Denmark)

    Orellana, Carlos Andrés Jurado

    on physical sound measurements. In this PhD thesis a detailed description of frequency selectivity at low frequencies is given. Different experiments have been performed to determine the properties of human auditory filters. Besides, loudness perception of low-frequency sinusoidal signals has been evaluated...

  11. Frequency agile solar radiotelescope

    Science.gov (United States)

    Bastian, Tim S.

    2003-02-01

    The Frequency Agile Solar Radiotelescope (FASR) is a solar-dedicated, ground based, interferometric array optimized to perform broadband imaging spectroscopy from ~ 0.1-30+ GHz. It will do so with the angular, spectral, and temporal resolution required to exploit radio emission from the Sun as a diagnostic of the wide variety of astrophysical processes that occur there. FASR represents a major advance over existing radioheliographs, and is expected to remain the world's premier solar radio instrument for two decades or more after completion. FASR will be a versatile and powerful instrument, providing unique data to a broad users community. Solar, solar-terrestrial, and space physicists will exploit FASR to attack a broad science program, including problems of fundamental interest: coronal magnetography, solar flares and particle acceleration, drivers of space weather, and the thermal structure and dynamics of the solar atmosphere. A design study and implementation planning are underway. Recent progress is reviewed here.

  12. Frequency scanning microstrip antennas

    DEFF Research Database (Denmark)

    Danielsen, Magnus; Jørgensen, Rolf

    1979-01-01

    The principles of using radiating microstrip resonators as elements in a frequency scanning antenna array are described. The resonators are cascade-coupled. This gives a scan of the main lobe due to the phase-shift in the resonator in addition to that created by the transmission line phase......-shift. Experimental results inX-band, in good agreement with the theory, show that it is possible to scan the main lobe an angle ofpm30degby a variation of the frequencypm300MHz, and where the 3 dB beamwidth is less than10deg. The directivity was 14.7 dB, while the gain was 8.1 dB. The efficiency might be improved...

  13. High frequency nanotube oscillator

    Science.gov (United States)

    Peng, Haibing [Houston, TX; Zettl, Alexander K [Kensington, TX

    2012-02-21

    A tunable nanostructure such as a nanotube is used to make an electromechanical oscillator. The mechanically oscillating nanotube can be provided with inertial clamps in the form of metal beads. The metal beads serve to clamp the nanotube so that the fundamental resonance frequency is in the microwave range, i.e., greater than at least 1 GHz, and up to 4 GHz and beyond. An electric current can be run through the nanotube to cause the metal beads to move along the nanotube and changing the length of the intervening nanotube segments. The oscillator can operate at ambient temperature and in air without significant loss of resonance quality. The nanotube is can be fabricated in a semiconductor style process and the device can be provided with source, drain, and gate electrodes, which may be connected to appropriate circuitry for driving and measuring the oscillation. Novel driving and measuring circuits are also disclosed.

  14. High Frequency Oscillatory Ventilation

    Directory of Open Access Journals (Sweden)

    AC Bryan

    1996-01-01

    Full Text Available High frequency oscillatory (HFO ventilation using low tidal volume and peak airway pressures is extremely efficient at eliminating carbon dioxide and raising pH in the newborn infant with acute respiratory failure. Improvement in oxygenation requires a strategy of sustained or repetitive inflations to 25 to 30 cm H2O in order to place the lung on the deflation limb of the pressure-volume curve. This strategy has also been shown to decrease the amount of secondary lung injury in animal models. Experience of the use of HFO ventilation as a rescue therapy as well as several published controlled trials have shown improved outcomes and a decrease in the use of extracorporeal membrane oxygenation when it has been used in newborns.

  15. Frequency doubling crystals

    Science.gov (United States)

    Wang, Francis; Velsko, Stephan P.

    1989-01-01

    A systematic approach to the production of frequency conversion crystals is described in which a chiral molecule has attached to it a "harmonic generating unit" which contributes to the noncentrosymmetry of the molecule. Certain preferred embodiments of such harmonic generating units include carboxylate, guanadyly and imidazolyl units. Certain preferred crystals include L-arginine fluoride, deuterated L-arginine fluoride, L-arginine chloride monohydrate, L-arginine acetate, dithallium tartrate, ammonium N-acetyl valine, N-acetyl tyrosine and N-acetyl hydroxyproline. Chemical modifications of the chiral molecule, such as deuteration, halogenation and controlled counterion substitution are available to adapt the dispersive properties of a crystal in a particular wavelength region.

  16. Radio Frequency Interference Mitigation

    Science.gov (United States)

    An, T.; Chen, X.; Mohan, P.; Lao, B. Q.

    2017-09-01

    The observational facilities of radio astronomy keep constant upgrades and developments to achieve better capabilities including increasing the time of the data recording and frequency resolutions, and increasing the receiving and recording bandwidth. However in contrast, only a limited spectrum resource has been allocated to radio astronomy by the International Telecommunication Union, resulting in that the radio observational instrumentations are inevitably exposed to undesirable radio frequency interference (RFI) signals which originate mainly from the terrestrial human activity and are becoming stronger with time. RFIs degrade the quality of data and even lead to invalid data. The impact of RFIs on scientific outcome becomes more and more serious. In this article, the requirement for RFI mitigation is motivated, and the RFI characteristics, mitigation techniques, and strategies are reviewed. The mitigation strategies adopted at some representative observatories, telescopes, and arrays are also introduced. The advantages and shortcomings of the four classes of RFI mitigation strategies are discussed and presented, applicable at the connected causal stages: preventive, pre-detection, pre-correlation, and post-correlation. The proper identification and flagging of RFI is the key to the reduction of data loss and improvement in data quality, and is also the ultimate goal of developing RFI mitigation technique. This can be achieved through a strategy involving a combination of the discussed techniques in stages. The recent advances in the high speed digital signal processing and high performance computing allow for performing RFI excision of the large data volumes generated from large telescopes or arrays in both real time and offline modes, aiding the proposed strategy.

  17. Robust power system frequency control

    CERN Document Server

    Bevrani, Hassan

    2014-01-01

    This updated edition of the industry standard reference on power system frequency control provides practical, systematic and flexible algorithms for regulating load frequency, offering new solutions to the technical challenges introduced by the escalating role of distributed generation and renewable energy sources in smart electric grids. The author emphasizes the physical constraints and practical engineering issues related to frequency in a deregulated environment, while fostering a conceptual understanding of frequency regulation and robust control techniques. The resulting control strategi

  18. Frequency effects in compound production

    NARCIS (Netherlands)

    Bien, H.; Levelt, W.J.M.; Baayen, R.H.

    2005-01-01

    Four experiments investigated the role of frequency information in compound production by independently varying the frequencies of the first and second constituent as well as the frequency of the compound itself. Pairs of Dutch noun-noun compounds were selected such that there was a maximal contrast

  19. Effects of attention on the control of locomotion in individuals with chronic low back pain

    Directory of Open Access Journals (Sweden)

    Kerckhoff Frederick

    2008-04-01

    Full Text Available Abstract Background People who suffer from low back pain (LBP exhibit an abnormal gait pattern, characterized by shorter stride length, greater step width, and an impaired thorax-pelvis coordination which may undermine functional walking. As a result, gait in LBP may require stronger cognitive regulation compared to pain free subjects thereby affecting the degree of automaticity of gait control. Conversely, because chronic pain has a strong attentional component, diverting attention away from the pain might facilitate a more efficient walking pattern. Methods Twelve individuals with LBP and fourteen controls participated. Subjects walked on a treadmill at comfortable speed, under varying conditions of attentional load: (a no secondary task, (b naming the colors of squares on a screen, (c naming the colors of color words ("color Stroop task", and (d naming the colors of words depicting motor activities. Markers were attached to the thorax, pelvis and feet. Motion was recorded using a three-camera SIMI system with a sample frequency of 100 Hz. To examine the effects of health status and attention on gait, mean and variability of stride parameters were calculated. The coordination between thoracic and pelvic rotations was quantified through the mean and variability of the relative phase between those oscillations. Results LBP sufferers had a lower walking speed, and consequently a smaller stride length and lower mean thorax-pelvis relative phase. Stride length variability was significantly lower in the LBP group but no significant effect of attention was observed. In both groups gait adaptations were found under performance of an attention demanding task, but significantly more so in individuals with LBP as indicated by an interaction effect on relative phase variability. Conclusion Gait in LBP sufferers was characterized by less variable upper body movements. The diminished flexibility in trunk coordination was aggravated under the influence of an

  20. Gait Adaptability Training Improves Both Postural Stability and Dual-Tasking Ability

    Science.gov (United States)

    Brady, Rachel A.; Batson, Crystal D.; Peters, Brian T.; Ploutz-Snyder, Robert J.; Mulavara, Ajitkumar P.; Bloomberg, Jacob J.

    2010-01-01

    After spaceflight, the process of readapting to Earth's gravity commonly presents crewmembers with a variety of locomotor challenges. Our recent work has shown that the ability to adapt to a novel discordant sensorimotor environment can be increased through preflight training, so one focus of our laboratory has been the development of a gait training countermeasure to expedite the return of normal locomotor function after spaceflight. We used a training system comprising a treadmill mounted on a motion base facing a virtual visual scene that provided a variety of sensory challenges. As part of their participation in a larger retention study, 10 healthy adults completed 3 training sessions during which they walked on a treadmill at 1.1 m/s while receiving discordant support-surface and visual manipulations. After a single training session, subjects stride frequencies improved, and after 2 training sessions their auditory reaction times improved, where improvement was indicated by a return toward baseline values. Interestingly, improvements in reaction time came after stride frequency improvements plateaued. This finding suggests that postural stability was given a higher priority than a competing cognitive task. Further, it demonstrates that improvement in both postural stability and dual-tasking can be achieved with multiple training exposures. We conclude that, with training, individuals become more proficient at walking in discordant sensorimotor conditions and are able to devote more attention to competing tasks.

  1. [Kinetics of heifers and cows walking on an instrumented treadmill].

    Science.gov (United States)

    Nuss, K; Waldern, N M; Weishaupt, M A; Wiestner, T

    2015-01-01

    Kinetic data of stride characteristics and ground reaction forces of cattle become increasingly important as automated lameness detection may be installed in dairy cow housing systems in the future. Therefore, sound heifers and cows were measured on an instrumented treadmill to collect such basic data. Nine heifers and 10 cows were trained to walk on an instrumented treadmill. Vertical ground reaction forces as well as step and stride timing and length variables were measured for all limbs simultaneously. On average, 16 stride cycles in cows and 24 strides in heifers were analysed in each case. The cows walked on the treadmill at an average speed of 1.2 ± 0.05 m/s (mean ± standard deviation), with a stride rate of 43.0 ± 1.9/min and a stride length of 1.68 ± 0.1 m. The heifers had average values of 1.3 ± 0.04 m/s, 53.7 ± 2.2/min and 1.49 ± 0.05 m, respectively. The stance duration relative to stride duration (the duty factor) was for the cows significantly longer in the forelimbs (67%) than in the hind limbs (64%). Force-time-curves of all limbs showed two peaks, one after landing (FP1) and another during push off (FP2). Vertical ground reaction force was highest for FP1 in the hind limbs, but for FP2 in the forelimbs. At all limbs, force minimum between the peaks occurred shortly before midstance. The vertical impulse carried by both forelimbs amounted to 53.7% of the total stride impulse in cows and to 55.0% in heifers. The location of the centre of body mass varied during the stride cycle but was always located more towards the front limbs. Cows and heifers showed a symmetrical walk with minimal intra-individual variations. Relative stride impulse of the front limbs was higher than that of the hind limbs. Peak vertical force in the hind limbs was highest at landing and in the forelimbs at push off. The present study offers kinetic data of sound cows and heifers which might be helpful as guidelines for automated systems for lameness detection in cattle.

  2. Effective switching frequency multiplier inverter

    Science.gov (United States)

    Su, Gui-Jia; Peng, Fang Z.

    2007-08-07

    A switching frequency multiplier inverter for low inductance machines that uses parallel connection of switches and each switch is independently controlled according to a pulse width modulation scheme. The effective switching frequency is multiplied by the number of switches connected in parallel while each individual switch operates within its limit of switching frequency. This technique can also be used for other power converters such as DC/DC, AC/DC converters.

  3. Binaural beats at high frequencies.

    Science.gov (United States)

    McFadden, D; Pasanen, E G

    1975-10-24

    Binaural beats have long been believed to be audible only at low frequencies, but an interaction reminiscent of a binaural beat can sometimes be heard when different two-tone complexes of high frequency are presented to the two ears. The primary requirement is that the frequency separation in the complex at one ear be slightly different from that in the other--that is, that there be a small interaural difference in the envelope periodicities. This finding is in accord with other recent demonstrations that the auditory system is not deaf to interaural time differences at high frequencies.

  4. Radio Frequency Anechoic Chamber Facility

    Data.gov (United States)

    Federal Laboratory Consortium — FUNCTION: Supports the design, manufacture, and test of antenna systems. The facility is also used as an electromagnetic compatibility/radio frequency interference...

  5. A graphene based frequency quadrupler

    Science.gov (United States)

    Cheng, Chuantong; Huang, Beiju; Mao, Xurui; Zhang, Zanyun; Zhang, Zan; Geng, Zhaoxin; Xue, Ping; Chen, Hongda

    2017-04-01

    Benefit from exceptional electrical transport properties, graphene receives worldwide attentions, especially in the domain of high frequency electronics. Due to absence of effective bandgap causing off-state the device, graphene material is extraordinarily suitable for analog circuits rather than digital applications. With this unique ambipolar behavior, graphene can be exploited and utilized to achieve high performance for frequency multipliers. Here, dual-gated graphene field-effect transistors have been firstly used to achieve frequency quadrupling. Two Dirac points in the transfer curves of the designed GFETs can be observed by tuning top-gate voltages, which is essential to generate the fourth harmonic. By applying 200 kHz sinusoid input, arround 50% of the output signal radio frequency power is concentrated at the desired frequency of 800 kHz. Additionally, in suitable operation areas, our devices can work as high performance frequency doublers and frequency triplers. Considered both simple device structure and potential superhigh carrier mobility of graphene material, graphene-based frequency quadruplers may have lots of superiorities in regards to ultrahigh frequency electronic applications in near future. Moreover, versatility of carbon material system is far-reaching for realization of complementary metal-oxide-semiconductor compatible electrically active devices.

  6. Discrete frequency slice wavelet transform

    Science.gov (United States)

    Yan, Zhonghong; Tao, Ting; Jiang, Zhongwei; Wang, Haibin

    2017-11-01

    This paper introduces a new kind of Time-Frequency Representation (TFR) method called Discrete Frequency Slice Wavelet Transform (DFSWT). It is an improved version of Frequency Slice Wavelet Transform (FSWT). The previous researches on FSWT show that it is a new efficient TFR in an easy way without strict limitation as traditional wavelet theory. DFSWT as well as FSWT are defined directly in frequency domain, and still keep its properties in time-frequency domain as FSWT decomposition, reconstruction and filter design, etc. However, the original signal is decomposed and reconstructed on a Chosen Frequency Domains (CFD) as need of application. CFD means that the decomposition and reconstruction are not completed on all frequency components. At first, it is important to discuss the necessary condition of CFD to reconstruct the original signal. And then based on norm l2, an optimization algorithm is introduced to reconstruct the original signal even accurately. Finally, for a test example, the TFR analysis of a real life signal is shown. Some conclusions are drawn that the concept of CFD is very useful to application, and the DFSWT can become a simple and easy tool of TFR method, and also provide a new idea of low speed sampling of high frequency signal in applications.

  7. Low-frequency-noise complaints

    DEFF Research Database (Denmark)

    Pedersen, Christian Sejer; Møller, Henrik; Persson-Waye, Kerstin

    2008-01-01

    From 203 cases of low-frequency complaints a random selection of twenty-one cases were investigated. The main aim of the investigation was to answer the question whether the annoyance is caused by an external physical sound or by a physically non-existing sound, i.e. low-frequency tinnitus. Noise...... of the complainants are annoyed by a physical sound (20-180 Hz), while others suffer from low-frequency tinnitus (perceived frequency 40-100 Hz). Physical sound at frequencies below 20 Hz (infrasound) is not responsible for the annoyance - or at all audible - in any of the investigated cases, and none...... of the complainants has extraordinary hearing sensitivity at low frequencies. For comparable cases of low-frequency noise complaints in general, it is anticipated that physical sound is responsible in a substantial part of the cases, while low-frequency tinnitus is responsible in another substantial part of the cases....

  8. Low frequency electromagnetic field sensor

    International Nuclear Information System (INIS)

    Zhu Min; Zhou Yan; He Yicheng; Zheng Zhenxing; Liu Sunkun

    2000-01-01

    The measurement technique of low frequency electromagnetic field is reported. According to this principle, the authors have designed a sensor, which is used to measure the natural electromagnetic field, SLEMP and electromagnetic signals generated by some explosions. The frequency band of this sensor is from 0.08 Hz to 2 MHz

  9. Lexical Frequency in Sign Languages

    Science.gov (United States)

    Johnston, Trevor

    2012-01-01

    Measures of lexical frequency presuppose the existence of corpora, but true machine-readable corpora of sign languages (SLs) are only now being created. Lexical frequency ratings for SLs are needed because there has been a heavy reliance on the interpretation of results of psycholinguistic and neurolinguistic experiments in the SL research…

  10. Gaming Frequency and Academic Performance

    Science.gov (United States)

    Ip, Barry; Jacobs, Gabriel; Watkins, Alan

    2008-01-01

    There are numerous claims that playing computer and video games may be educationally beneficial, but there has been little formal investigation into whether or not the frequency of exposure to such games actually affects academic performance. This paper explores the issue by analysing the relationships between gaming frequency--measured as the…

  11. Micronuclei Frequency in Radiation Worker

    International Nuclear Information System (INIS)

    Sudprasert, Wanwisa; Jungtanasombut, Amornrat; Pakkong, Pannee

    2009-07-01

    Full text: The purpose of this study is to determine the micronuclei (MN) frequency in peripheral blood lymphocytes of 31 individuals occupationally exposed to radiation compared to 24 controls. The effect of donor gender, age, alcoholic consumption, tea/coffee consumption and radiation burden on MN frequency was studied. The results showed that MN frequencies observed for exposed employees were significantly higher than in controls (p = 0.000). The average MN frequency in control was 39.1 ± 3.7 MN/1000 BN while those of exposed group were 60.9 ± 12.3, 61.6 ± 13.0 and 62.6 ± 11.8 MN/1000 BN for the range of accumulative doses at 0.01-3.00, 3.01-6.00 and 6.01-9.00 mSv, respectively. Moreover, MN frequency showed a positive trend with increased accumulative doses as a linear-quadratic relation (R 2 = 0.4754). No correlation of MN frequency with gender, age and alcoholic consumption could be observed in both exposed and control groups. However, the effect of tea/coffee consumption on MN frequency was clearly observed in the exposed individuals (t-test = -2.018, sig. (2-tailed) = 0.030). These results indicate that the increased MN frequency, an indicator of chromosomal aberration, is associated with occupational exposure to low doses of ionizing radiation

  12. The association between fear of falling and gait variability in both leg and trunk movements.

    Science.gov (United States)

    Sawa, Ryuichi; Doi, Takehiko; Misu, Shogo; Tsutsumimoto, Kota; Nakakubo, Sho; Asai, Tsuyoshi; Yamada, Minoru; Ono, Rei

    2014-01-01

    The aim of this study was to explore whether FoF was associated with variability in both leg and trunk movements during gait in community-dwelling elderly. Ninety-three elderly people participated in this study. Each participant was categorized into either Fear or No-Fear group on the basis of having FoF. The participants walked 15m at their preferred speed. The wireless motion recording sensor units were attached to L3 spinous process and right posterior surface of heel during gait. Gait velocity, stride time and stride length were calculated. Variability in lower limb movements was represented by coefficient of variation (CV) of stride time. Trunk variability was represented by autocorrelation coefficients (AC) in three directions (vertical: VT, mediolateral: ML and anteroposterior: AP), respectively. Gait parameters were compared between groups, and further analyses were performed using generalized linear regression models after adjustment of age, sex, fall experience, height, weight, and gait velocity. Although gait velocity, mean stride time and stride length did not differ significantly between groups, stride time CV and all ACs were significantly worse in the Fear group after adjustment for variables, even including gait velocity (stride time CV: p=0.003, β=-0.793; AC-VT: p=0.011, β=0.053; AC-ML: p=0.044, β=0.075; AC-AP: p=0.002, β=0.078). Our results suggest that fear of falling is associated with variability in both leg and trunk movements during gait in community-dwelling elderly. Further studies are needed to prove a causal relationship. Copyright © 2014. Published by Elsevier B.V.

  13. Effects of noxious stimulation to the back or calf muscles on gait stability.

    Science.gov (United States)

    van den Hoorn, Wolbert; Hug, François; Hodges, Paul W; Bruijn, Sjoerd M; van Dieën, Jaap H

    2015-11-26

    Gait stability is the ability to deal with small perturbations that naturally occur during walking. Changes in motor control caused by pain could affect this ability. This study investigated whether nociceptive stimulation (hypertonic saline injection) in a low back (LBP) or calf (CalfP) muscle affects gait stability. Sixteen participants walked on a treadmill at 0.94ms(-1) and 1.67ms(-1), while thorax kinematics were recorded using 3D-motion capture. From 110 strides, stability (local divergence exponent, LDE), stride-to-stride variability and root mean squares (RMS) of thorax linear velocities were calculated along the three movement axes. At 0.94ms(-1), independent of movement axes, gait stability was lower (higher LDE) and stride-to-stride variability was higher, during LBP and CalfP than no pain. This was more pronounced during CalfP, likely explained by the biomechanical function of calf muscles in gait, as supported by greater mediolateral RMS and stance time asymmetry than in LBP and no pain. At 1.67ms(-1), independent of movement axes, gait stability was greater and stride-to-stride variability was smaller with LBP than no pain and CalfP, whereas CalfP was not different from no pain. Opposite effects of LBP on gait stability between speeds suggests a more protective strategy at the faster speed. Although mediolateral RMS was greater and participants had more asymmetric stance times with CalfP than LBP and no pain, limited effect of CalfP at the faster speed could relate to greater kinematic constraints and smaller effects of calf muscle activity on propulsion at this speed. In conclusion, pain effects on gait stability depend on pain location and walking speed. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Does Footwear Matter When Performing Spatiotemporal Gait Analysis Among Older Women?

    Science.gov (United States)

    Roman de Mettelinge, Tine; Calders, Patrick; Danneels, Evy; Geeroms, Sofie; Du Four, Céline; Cambier, Dirk

    2015-01-01

    Although shoe type may influence gait performance and is considered to be an extrinsic fall risk factor, little or no attention is paid to it when conducting research in this field. Therefore, this study aimed to assess the effect of various types of footwear under single- and dual-task conditions on spatiotemporal gait characteristics in older women. Fifty-seven community-dwelling women (68.0 ± 4.6 years) were enrolled in this study. Spatiotemporal gait analysis using the GAITRite walkway was performed under 4 footwear conditions (barefoot, slippers, high heels, and standard shoes) and 3 task conditions (single-task, motor dual-task, and cognitive dual-task). Two-factor repeated-measures analysis of variance was conducted. Primary outcomes were velocity, cadence, stride time, stride length, and stride length variability. Irrespective of task condition, walking barefoot resulted in a significantly slower gait pattern with decreased cadence and stride length and increased stride time and stride length variability compared with walking with the standard shoe. These significant gait alterations were also observed when adding a cognitive task to normal walking. The effects of footwear were most obvious during the cognitive dual-task condition and for the spatiotemporal parameters velocity and stride length. Footwear matters when analyzing gait in older women. It should be described in greater detail by gait researchers. Footwear should also be considered by clinicians in light of the study findings and its effects on gait. Older women are strongly discouraged to walk barefoot because barefoot walking adversely affects gait patterns. A well-fitting standard shoe with laces, a low and wide heel, firm heel collar and a grooved, moderately hard sole is recommended in research, rehabilitation, and daily use.

  15. Speed-related spinal excitation from ankle dorsiflexors to knee extensors during human walking

    DEFF Research Database (Denmark)

    Iglesias, Caroline; Nielsen, Jens Bo; Marchand-Pauvert, Véronique

    2008-01-01

    investigated the CPQ-reflex at different walking speeds (1-6 km/h) and stride frequencies (0.6-1.3 Hz) in healthy human subjects to provide further evidence of its modulation, and its role in ensuring postural stability during walking. The CPQ-reflex was small or absent at walking speeds below 2-3 km....../h, then increased with walking speeds about 3-4 km/h, and reached a plateau without any further change at walking speeds from 4 to 6 km/h. The reflex showed no modulation when the stride cycle was varied at constant speed (4 km/h; short steps versus long steps). These changes were unlikely to be only caused...... by changes in the background EMG activity and modifications in peripheral input, and likely reflected central modulation of transmission in the involved reflex pathways as well. It is suggested that the purpose of the reflex is to ensure knee stability at moderate-to-high walking speeds....

  16. It's just sand between the toes: how particle size and shape variation affect running performance and kinematics in a generalist lizard.

    Science.gov (United States)

    Bergmann, Philip J; Pettinelli, Kyle J; Crockett, Marian E; Schaper, Erika G

    2017-10-15

    Animals must cope with and be able to move effectively on a variety of substrates. Substrates composed of granular media, such as sand and gravel, are extremely common in nature, and vary tremendously in particle size and shape. Despite many studies of the properties of granular media and comparisons of locomotion between granular and solid substrates, the effects of systematically manipulating these media on locomotion is poorly understood. We studied granular media ranging over four orders of magnitude in particle size, and differing in the amount of particle shape variation, to determine how these factors affected substrate physical properties and sprinting in the generalist lizard Eremias arguta We found that media with intermediate particle sizes had high bulk densities, low angles of stability and low load-bearing capacities. Rock substrates with high shape variation had higher values for all three properties than glass bead substrates with low shape variation. We found that E. arguta had the highest maximum velocities and accelerations on intermediate size particles, and higher velocities on rock than glass beads. Lizards had higher stride frequencies and lower duty factors on intermediate particle size substrates, but their stride lengths did not change with substrate. Our findings suggest that sand and gravel may represent different locomotor challenges for animals. Sand substrates provide animals with an even surface for running, but particles shift underfoot. In contrast, gravel particles are heavy, so move far less underfoot, yet provide the animal with an uneven substrate. © 2017. Published by The Company of Biologists Ltd.

  17. Identification of mouse gaits using a novel force-sensing exercise wheel

    Science.gov (United States)

    Cullingford, Lottie; Usherwood, James R.

    2015-01-01

    The gaits that animals use can provide information on neurological and musculoskeletal disorders, as well as the biomechanics of locomotion. Mice are a common research model in many fields; however, there is no consensus in the literature on how (and if) mouse gaits vary with speed. One of the challenges in studying mouse gaits is that mice tend to run intermittently on treadmills or overground; this paper attempts to overcome this issue with a novel exercise wheel that measures vertical ground reaction forces. Unlike previous instrumented wheels, this wheel is able to measure forces continuously and can therefore record data from consecutive strides. By concatenating the maximum limb force at each time point, a force trace can be constructed to quantify and identify gaits. The wheel was three dimensionally printed, allowing the design to be shared with other researchers. The kinematic parameters measured by the wheel were evaluated using high-speed video. Gaits were classified using a metric called “3S” (stride signal symmetry), which quantifies the half wave symmetry of the force trace peaks. Although mice are capable of using both symmetric and asymmetric gaits throughout their speed range, the continuum of gaits can be divided into regions based on the frequency of symmetric and asymmetric gaits; these divisions are further supported by the fact that mice run less frequently at speeds near the boundaries between regions. The boundary speeds correspond to gait transition speeds predicted by the hypothesis that mice move in a dynamically similar fashion to other legged animals. PMID:26139220

  18. Lateral Squats Significantly Decrease Sprint Time in Collegiate Baseball Athletes

    Directory of Open Access Journals (Sweden)

    Jason B. White

    2016-03-01

    Full Text Available The purpose was to examine the effect of prior performance of dumbbell lateral squats (DBLS on an agility movement-into-a-sprint (AMS test. Twelve collegiate, resistance-trained, baseball athletes participated in three sessions separated by three days. Session One consisted of AMS baseline test, DBLS 5-RM test, and experimental protocol familiarization. Subjects were randomly assigned the protocol order for Sessions Two and Three, which consisted of warm up followed by 1-min sitting (no-DBLS or performing the DBLS for 1 × 5 repetitions @ 5RM for each leg. Four minutes of slow recovery walking preceded the AMS test, which consisted of leading off a base and waiting for a visual stimulus. In reaction to stimulus, subjects exerted maximal effort while moving to the right by either pivoting or drop stepping and sprinting for 10 yards (yd. In Session Three, subjects switched protocols (DBLS, no-DBLS. Foot contact time (FCT, stride frequency (SF, stride length (SL, and 10-yd sprint time were measured. There were no differences between conditions for FCT, SF, or SL. Differences existed between DBLS (1.85 ± 0.09 s and no-DBLS (1.89 ± 0.10 s for AMS (p = 0.03. Results from the current study support the use of DBLS for performance enhancement prior to performing the AMS test.

  19. Development of a lower limb rehabilitation exoskeleton based on real-time gait detection and gait tracking

    Directory of Open Access Journals (Sweden)

    Chao Zhang

    2016-01-01

    Full Text Available Hemiplegia, apoplexia, or traffic accidents often lead to unilateral lower limb movement disorders. Traditional lower limb rehabilitation equipments usually execute walk training based on fixed gait trajectory; however, this type is unsuitable for unilateral lower limb disorders because they still have athletic ability and initiative walking intention on the healthy side. This article describes a wearable lower limb rehabilitation exoskeleton with a walk-assisting platform for safety and anti-gravity support. The exoskeleton detects and tracks the motion of the healthy leg, which is then used as the control input of the dyskinetic leg with half a gate-cycle delay. The patient can undergo walk training on his own intention, including individual walking habit, stride length, and stride frequency, which likely contribute to the training initiative. The series elastic actuator is chosen for the exoskeleton because the torque output can be accurately detected and used to calculate the assisted torque on the dyskinetic leg. This parameter corresponds to the recovery level of a patient’s muscle force. Finally, the walk-assisting experiments reveal that the rehabilitation exoskeleton in this article can provide the necessary assisting torques on the dyskinetic leg, which can be accurately monitored in real time to evaluate a patient’s rehabilitation status.

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

    Science.gov (United States)

    Yang, Shuozhi; Li, Qingguo

    2012-01-01

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

  1. Velocity correlations and spatial dependencies between neighbors in a unidirectional flow of pedestrians

    Science.gov (United States)

    Porzycki, Jakub; WÄ s, Jarosław; Hedayatifar, Leila; Hassanibesheli, Forough; Kułakowski, Krzysztof

    2017-08-01

    The aim of the paper is an analysis of self-organization patterns observed in the unidirectional flow of pedestrians. On the basis of experimental data from Zhang et al. [J. Zhang et al., J. Stat. Mech. (2011) P06004, 10.1088/1742-5468/2011/06/P06004], we analyze the mutual positions and velocity correlations between pedestrians when walking along a corridor. The angular and spatial dependencies of the mutual positions reveal a spatial structure that remains stable during the crowd motion. This structure differs depending on the value of n , for the consecutive n th -nearest-neighbor position set. The preferred position for the first-nearest neighbor is on the side of the pedestrian, while for further neighbors, this preference shifts to the axis of movement. The velocity correlations vary with the angle formed by the pair of neighboring pedestrians and the direction of motion and with the time delay between pedestrians' movements. The delay dependence of the correlations shows characteristic oscillations, produced by the velocity oscillations when striding; however, a filtering of the main frequency of individual striding out reduces the oscillations only partially. We conclude that pedestrians select their path directions so as to evade the necessity of continuously adjusting their speed to their neighbors'. They try to keep a given distance, but follow the person in front of them, as well as accepting and observing pedestrians on their sides. Additionally, we show an empirical example that illustrates the shape of a pedestrian's personal space during movement.

  2. High Frequency Electronic Packaging Technology

    Science.gov (United States)

    Herman, M.; Lowry, L.; Lee, K.; Kolawa, E.; Tulintseff, A.; Shalkhauser, K.; Whitaker, J.; Piket-May, M.

    1994-01-01

    Commercial and government communication, radar, and information systems face the challenge of cost and mass reduction via the application of advanced packaging technology. A majority of both government and industry support has been focused on low frequency digital electronics.

  3. Global Multihazard Frequency and Distribution

    Data.gov (United States)

    National Aeronautics and Space Administration — Global Multihazard Frequency and Distribution is a 2.5 minute grid presenting a simple multihazard index based solely on summated single-hazard decile values. The...

  4. Geographies of High Frequency Trading

    DEFF Research Database (Denmark)

    Grindsted, Thomas Skou

    2016-01-01

    This paper investigates the geographies of high frequency trading. Today shares shift hands within micro seconds, giving rise to a form of financial geographies termed algorithmic capitalism. This notion refers to the different spatio-temporalities produced by high frequency trading, under...... the valuation of time. As high frequency trading accelerates financial markets, the paper examines the spatio-temporalities of automated trading by the ways in which the speed of knowledge exploitation in financial markets is not only of interest, but also the expansion between different temporalities....... The paper demonstrates how the intensification of time-space compression produces radical new dynamics in the financial market and develops information rent in HFT as convertible to a time rent and a spatio-temporal rent. The final section discusses whether high frequency trading only responds to crises...

  5. Radio Frequency Signal Propagation Study

    Science.gov (United States)

    2014-02-01

    and software solutions UNCLASSIFIED 5 UNCLASSIFIED DSTO-TR-2868 number of variables to select including the waveform used and whether the platform...the road. Transmission licences for the following five frequencies were obtained, 1216, 1270, 1399, 1525 and 1650 MHz. These frequencies were...Institution of Electrical Engineers, 2000 7. Matlab Software Package QPEM, Written by Richard Hawkes, APNT Group, CEWD, DSTO 8. Parsons, JD

  6. Lossless equalization of frequency combs

    OpenAIRE

    Torres Company, Víctor; Lancis Sáez, Jesús; Andrés, Pedro

    2008-01-01

    Frequency combs obtained by sinusoidal phase modulation of narrow-band continuous-wave lasers are widely used in the field of optical communications. However, the resulting spectral envelope of the comb is not at. In this Letter, we propose a general and eficient approach to achieve at frequency combs with tunable bandwidth. The idea is based on a two-step process. First, eficient generation of a train with temporal at-top-pulse profile is required. Second, we use larg...

  7. Gaming frequency and academic performance

    OpenAIRE

    Ip, Barry; Jacobs, Gabriel; Watkins, Alan

    2008-01-01

    There are numerous claims that playing computer and video games may be educationally beneficial, but there has been little formal investigation into whether or not the frequency of exposure to such games actually affects academic performance. This paper explores the issue by analysing the relationships between gaming frequency –measured as the amount of time undergraduate students spend playing games in their free time – and their academic performance as measured by their examination marks. U...

  8. Iodine frequency references for space

    International Nuclear Information System (INIS)

    Schuldt, Thilo; Braxmaier, Claus; Döringshoff, Klaus; Peters, Achim; Oswald, Markus; Johann, Ulrich

    2017-01-01

    Optical frequency references are a key element for the realization of future space missions. They are needed for missions related to tests of fundamental physics, gravitational wave detection, Earth observation and navigation and ranging. In missions such as GRACE follow-on or LISA the optical frequency reference is used as light source for high-sensitivity inter-satellite distance metrology. While cavity-based systems are current baseline e.g. for LISA, frequency stabilization on a hyperfine transition in molecular iodine near 532 nm is a promising alternative. Due to its absolute frequency, iodine standards crucially simplify the initial spacecraft acquisition procedures. Current setups fulfill the GRACE-FO and LISA frequency stability requirements and are realized near Engineering Model level. We present the current status of our developments on Elegant Breadboard (EBB) and Engineering Model (EM) level taking into account specific design criteria for space compatibility such as compactness (size iodine spectroscopy EM: 38 × 18 × 10 cm 3 ) and robustness. Both setups achieved similar frequency stabilities of ∼ 1 · 10 −14 at an integration time of 1 s and below 5 · 10 −15 at integration times between 10 s and 1000 s. Furthermore, we present an even more compact design currently developed for a sounding rocket mission with launch in 2017. (paper)

  9. Iodine frequency references for space

    Science.gov (United States)

    Schuldt, Thilo; Döringshoff, Klaus; Oswald, Markus; Johann, Ulrich; Peters, Achim; Braxmaier, Claus

    2017-05-01

    Optical frequency references are a key element for the realization of future space missions. They are needed for missions related to tests of fundamental physics, gravitational wave detection, Earth observation and navigation and ranging. In missions such as GRACE follow-on or LISA the optical frequency reference is used as light source for high-sensitivity inter-satellite distance metrology. While cavity-based systems are current baseline e.g. for LISA, frequency stabilization on a hyperfine transition in molecular iodine near 532 nm is a promising alternative. Due to its absolute frequency, iodine standards crucially simplify the initial spacecraft acquisition procedures. Current setups fulfill the GRACE-FO and LISA frequency stability requirements and are realized near Engineering Model level. We present the current status of our developments on Elegant Breadboard (EBB) and Engineering Model (EM) level taking into account specific design criteria for space compatibility such as compactness (size iodine spectroscopy EM: 38 × 18 × 10 cm3) and robustness. Both setups achieved similar frequency stabilities of ˜ 1 · 10-14 at an integration time of 1 s and below 5 · 10-15 at integration times between 10 s and 1000 s. Furthermore, we present an even more compact design currently developed for a sounding rocket mission with launch in 2017.

  10. Demand as frequency controlled reserve

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Z.; Togeby, M.; OEstergaard, J.

    2008-09-15

    Using demand as frequency controlled reserve (DFR) is an emerging technology which allow demand to participate actively in maintaining the system operation without reducing the energy service delivered to the customer and without need of user interaction. The basic premise is that traditional frequency controlled reserves from power plants and interconnections with neighbouring systems can be costly, slow and not fulfil the need for future power grids with a high share of wind power and fewer central power plants, and an intention to perform flexible operation such as is landing. Electricity demands, on the other hand, have advantages as frequency reserve including fast activation speed, smooth linear activation, low expected costs, and well-dispersed in the distribution grid. The main challenge of DFR is new methods for monitoring the available capacity. This project has investigated the technology of using electricity demands for providing frequency reserve to power systems. Within the project the potential and economy of DFR compatible loads in Denmark has been investigated, control logic has been designed, power system impact has been investigated, potential business models has been evaluated and an implementation strategy has been suggested. The tasks and goals of the project have been successfully accomplished based on which the conclusion and future recommendation are made. This project has developed the DFR technology that enables electricity demands to autonomously disconnect or reconnect to the grid in response to system frequency variations. The developed DFR technology is proved to be a promising technology from several perspectives. Technically, using DFR is feasible to provide reserves and enhance power system frequency control, while fulfilling technical requirements such as linear activation (or reconnection) according to frequency (or time). Environmentally, the DFR technology is pollution free in contrast to traditional reserves from generation

  11. KINETIC CONSEQUENCES OF CONSTRAINING RUNNING BEHAVIOR

    Directory of Open Access Journals (Sweden)

    John A. Mercer

    2005-06-01

    Full Text Available It is known that impact forces increase with running velocity as well as when stride length increases. Since stride length naturally changes with changes in submaximal running velocity, it was not clear which factor, running velocity or stride length, played a critical role in determining impact characteristics. The aim of the study was to investigate whether or not stride length influences the relationship between running velocity and impact characteristics. Eight volunteers (mass=72.4 ± 8.9 kg; height = 1.7 ± 0.1 m; age = 25 ± 3.4 years completed two running conditions: preferred stride length (PSL and stride length constrained at 2.5 m (SL2.5. During each condition, participants ran at a variety of speeds with the intent that the range of speeds would be similar between conditions. During PSL, participants were given no instructions regarding stride length. During SL2.5, participants were required to strike targets placed on the floor that resulted in a stride length of 2.5 m. Ground reaction forces were recorded (1080 Hz as well as leg and head accelerations (uni-axial accelerometers. Impact force and impact attenuation (calculated as the ratio of head and leg impact accelerations were recorded for each running trial. Scatter plots were generated plotting each parameter against running velocity. Lines of best fit were calculated with the slopes recorded for analysis. The slopes were compared between conditions using paired t-tests. Data from two subjects were dropped from analysis since the velocity ranges were not similar between conditions resulting in the analysis of six subjects. The slope of impact force vs. velocity relationship was different between conditions (PSL: 0.178 ± 0.16 BW/m·s-1; SL2.5: -0.003 ± 0.14 BW/m·s-1; p < 0.05. The slope of the impact attenuation vs. velocity relationship was different between conditions (PSL: 5.12 ± 2.88 %/m·s-1; SL2.5: 1.39 ± 1.51 %/m·s-1; p < 0.05. Stride length was an important factor

  12. When Human Walking is a Random Walk

    Science.gov (United States)

    Hausdorff, J. M.

    1998-03-01

    The complex, hierarchical locomotor system normally does a remarkable job of controlling an inherently unstable, multi-joint system. Nevertheless, the stride interval --- the duration of a gait cycle --- fluctuates from one stride to the next, even under stationary conditions. We used random walk analysis to study the dynamical properties of these fluctuations under normal conditions and how they change with disease and aging. Random walk analysis of the stride-to-stride fluctuations of healthy, young adult men surprisingly reveals a self-similar pattern: fluctuations at one time scale are statistically similar to those at multiple other time scales (Hausdorff et al, J Appl Phsyiol, 1995). To study the stability of this fractal property, we analyzed data obtained from healthy subjects who walked for 1 hour at their usual pace, as well as at slower and faster speeds. The stride interval fluctuations exhibited long-range correlations with power-law decay for up to a thousand strides at all three walking rates. In contrast, during metronomically-paced walking, these long-range correlations disappeared; variations in the stride interval were uncorrelated and non-fractal (Hausdorff et al, J Appl Phsyiol, 1996). To gain insight into the mechanism(s) responsible for this fractal property, we examined the effects of aging and neurological impairment. Using detrended fluctuation analysis (DFA), we computed α, a measure of the degree to which one stride interval is correlated with previous and subsequent intervals over different time scales. α was significantly lower in healthy elderly subjects compared to young adults (p < .003) and in subjects with Huntington's disease, a neuro-degenerative disorder of the central nervous system, compared to disease-free controls (p < 0.005) (Hausdorff et al, J Appl Phsyiol, 1997). α was also significantly related to degree of functional impairment in subjects with Huntington's disease (r=0.78). Recently, we have observed that just as

  13. Frequency dependent polarization in blazars

    International Nuclear Information System (INIS)

    Bjoernsson, C.I.

    1984-10-01

    It is argued that the intrinsic frequency dependent polarization in blazars finds its most straightforward explanations in terms of a single rather than a multicomponent sourcemodel. In order to reproduce the observations, under the assumption that the emission mechanism is optically thin synchrotron radiation, both a well ordered magnetic field and an electron distribution with a sharp break or cuttoff are necessary. Non-uniform pitch angle distribution and/or environments where synchrotron losses are important are both conducive to producing strong frequency dependent polarization. Reasons are put forth as to why such conditions ar expected to occur in blazars. Two specific models are discussed in detail and it is shown that they are both able to produce strong frequency dependent polarization, even when the spectral index changes by a small amount only. (orig.)

  14. The instantaneous frequency rate spectrogram

    Science.gov (United States)

    Czarnecki, Krzysztof

    2016-01-01

    An accelerogram of the instantaneous phase of signal components referred to as an instantaneous frequency rate spectrogram (IFRS) is presented as a joint time-frequency distribution. The distribution is directly obtained by processing the short-time Fourier transform (STFT) locally. A novel approach to amplitude demodulation based upon the reassignment method is introduced as a useful by-product. Additionally, an estimator of energy density versus the instantaneous frequency rate (IFR) is proposed and referred to as the IFR profile. The energy density is estimated based upon both the classical energy spectrogram and the IFRS smoothened by the median filter. Moreover, the impact of an analyzing window width, additive white Gaussian noise and observation time is tested. Finally, the introduced method is used for the analysis of the acoustic emission of an automotive engine. The recording of the engine of a Lamborghini Gallardo is analyzed as an example.

  15. radio frequency emf radio frequency emf exposure due to gsm

    African Journals Online (AJOL)

    eobe

    which is 9mW/m2 for the public and 22.5mW/m2 for those professionals invo for those professionals involved in telecommunication industry. lved in telecommunication industry. lved in telecommunication industry. Keywords: Radio Frequency Electromagnetic Radiation, Base Station Antenna, Power density, international.

  16. Increased gait unsteadiness in community-dwelling elderly fallers

    Science.gov (United States)

    Hausdorff, J. M.; Edelberg, H. K.; Mitchell, S. L.; Goldberger, A. L.; Wei, J. Y.

    1997-01-01

    OBJECTIVE: To test the hypothesis that quantitative measures of gait unsteadiness are increased in community-dwelling elderly fallers. STUDY DESIGN: Retrospective, case-control study. SETTING: General community. PARTICIPANTS: Thirty-five community-dwelling elderly subjects older than 70 years of age who were capable of ambulating independently for 6 minutes were categorized as fallers (age, 82.2 +/- 4.9 yrs [mean +/- SD]; n = 18) and nonfallers (age, 76.5 +/- 4.0 yrs; n = 17) based on history; 22 young (age, 24.6 +/- 1.9 yrs), healthy subjects also participated as a second reference group. MAIN OUTCOME MEASURES: Stride-to-stride variability (standard deviation and coefficient of variation) of stride time, stance time, swing time, and percent stance time measured during a 6-minute walk. RESULTS: All measures of gait variability were significantly greater in the elderly fallers compared with both the elderly nonfallers and the young subjects (p elderly fallers was similar to that of the nonfallers. There were little or no differences in the variability measures of the elderly nonfallers compared with the young subjects. CONCLUSIONS: Stride-to-stride temporal variations of gait are relatively unchanged in community-dwelling elderly nonfallers, but are significantly increased in elderly fallers. Quantitative measurement of gait unsteadiness may be useful in assessing fall risk in the elderly.

  17. Description of spatio-temporal gait parameters in elderly people and their association with history of falls: results of the population-based cross-sectional KORA-Age study.

    Science.gov (United States)

    Thaler-Kall, Kathrin; Peters, Annette; Thorand, Barbara; Grill, Eva; Autenrieth, Christine S; Horsch, Alexander; Meisinger, Christa

    2015-03-25

    In this epidemiological study we described the characteristics of spatio-temporal gait parameters among a representative, population-based sample of 890 community-dwelling people aged 65 to 90 years. In addition, we investigated the associations between certain gait parameters and a history of falls in study participants. In descriptive analyses spatio-temporal gait parameters were assessed according to history of falls, frailty, multimorbidity, gender, multiple medication use, disability status, and age group. Logistic regression models were calculated to examine the association between gait velocity and stride length with a history of falls (at least one fall in the last 12 month). Data on gait were collected on an electronic walkway on which participants walked at their usual pace. We found significant differences within gait parameters when stratifying by frailty, multimorbidity, disability and multiple medication use as well as age (cut point 75 years) and sex, with p gait parameters (velocity, cadence, time, stride duration, stride length, step width). After stratification by history of falls, only stride length showed a significant difference (p gait parameters measured during gait assessment on an electronic walkway in elderly people. Furthermore, stride length is a good indicator to differentiate fallers from non-fallers in older men from the general population.

  18. Spatiotemporal characteristics of motor actions by blind long jump athletes.

    Science.gov (United States)

    Torralba, Miguel Angel; Padullés, José María; Losada, Jose Luis; López, Jose Luis

    2017-01-01

    Blind people depend on spatial and temporal representations to perform activities of daily living and compete in sport. The aim of this study is to determine the spatiotemporal characteristics of long jumps performed by blind athletes and compare findings with those reported for sighted athletes. We analysed a sample of 12 male athletes competing in the F11 Long Jump Finals at the Paralympic Games in London 2012. Performances were recorded using four high-speed cameras, and speeds were measured using a radar speed gun. The images were processed using validated image analysis software. The long jump run-up is shorter in blind athletes than in sighted athletes. We observed statistically significant differences for body centre of mass velocity and an increase in speed over the last three strides prior to take-off, contrasting with reports for sighted athletes and athletes with less severe visual impairment, who maintain or reduce their speed during the last stride. Stride length for the last three strides was the only spatial characteristic that was not significantly associated with effective jump distance. Blind long jumpers extend rather than shorten their last stride. Contact time with the take-off board is longer than that reported for sighted athletes. The actions of blind long jumpers, unlike those without disabilities, do not vary their leg actions during the final runway approach for optimal placement on the take-off board.

  19. Differences in hip range of motion among collegiate pitchers when compared to youth and professional baseball pitcher data.

    Science.gov (United States)

    Cheatham, Scott W; Shimamura, Kathryn Kumagai; Kolber, Morey J

    2016-09-01

    The purpose of this study was to measure passive hip internal (IR) and external rotation (ER) range of motion (ROM) in collegiate baseball pitchers and compare to published youth and professional values. Measures were taken on the bilateral hips of 29 participants (mean age 20.0±1.4, range 18-22 years). Results identified no significant differences between the stance and stride hip in collegiate right handed pitchers for IR (p= 0.22, ES 0.23) and ER (p=.08, ES= 0.25). There was no significant difference in left handed pitchers for IR (p= 0.80, ES= 0.11) and ER (p= 0.56, ES= 0.15). When comparing youth to collegiate, IR increased in the stance (2º) and stride (5º) hip and an increase in the stance (5º) and stride (5º) hip were present for ER as well. From collegiate to professional, IR increased in the stance (4º) and stride (3º) hip whereas a decrease in the stance (9º) and stride (12º) hip was present for ER. The data suggests an increase in passive ROM from youth to collegiate and a decrease from collegiate to professional. Understanding passive hip ROM values among the different levels of pitchers may assist clinicians in developing time dependent interventions to prevent future injury and enhance performance.

  20. Lower Extremity Muscle Activation and Kinematics of Catchers When Throwing Using Various Squatting and Throwing Postures

    Directory of Open Access Journals (Sweden)

    Yi-Chien Peng, Kuo-Cheng Lo, Lin-Hwa Wang

    2015-09-01

    Full Text Available This study investigated the differences in joint motions and muscle activities of the lower extremities involved in various squatting postures. The motion capture system with thirty-one reflective markers attached on participants was used for motion data collection. The electromyography system was applied over the quadriceps, biceps femoris, tibialis anterior, and gastrocnemius muscles of the pivot and stride leg. The joint extension and flexion in wide squatting are greater than in general squatting (p = 0.005. Knee joint extension and flexion in general squatting are significantly greater than in wide squatting (p = 0.001. The adduction and abduction of the hip joint in stride passing are significantly greater than in step squatting (p = 0.000. Furthermore, the adduction and abduction of the knee joint in stride passing are also significantly greater than in step squatting (p = 0.000. When stride passing is performed, the muscle activation of the hamstring of the pivot foot in general squatting is significantly greater than in wide squatting (p < 0.05, and this difference continues to the stride period. Most catchers use a general or wide squatting width, exclusive of a narrow one. Therefore, the training design for strengthening the lower extremity muscles should consider the appropriateness of the common squat width to enhance squat-up performance. For lower limb muscle activation, wide squatting requires more active gastrocnemius and tibialis anterior muscles. Baseball players should extend the knee angle of the pivot foot before catching the ball.

  1. Spatiotemporal characteristics of motor actions by blind long jump athletes

    Science.gov (United States)

    Torralba, Miguel Angel; Padullés, José María; Losada, Jose Luis; López, Jose Luis

    2017-01-01

    Background Blind people depend on spatial and temporal representations to perform activities of daily living and compete in sport. Objective The aim of this study is to determine the spatiotemporal characteristics of long jumps performed by blind athletes and compare findings with those reported for sighted athletes. Methods We analysed a sample of 12 male athletes competing in the F11 Long Jump Finals at the Paralympic Games in London 2012. Performances were recorded using four high-speed cameras, and speeds were measured using a radar speed gun. The images were processed using validated image analysis software. Results The long jump run-up is shorter in blind athletes than in sighted athletes. We observed statistically significant differences for body centre of mass velocity and an increase in speed over the last three strides prior to take-off, contrasting with reports for sighted athletes and athletes with less severe visual impairment, who maintain or reduce their speed during the last stride. Stride length for the last three strides was the only spatial characteristic that was not significantly associated with effective jump distance. Blind long jumpers extend rather than shorten their last stride. Contact time with the take-off board is longer than that reported for sighted athletes. Conclusion The actions of blind long jumpers, unlike those without disabilities, do not vary their leg actions during the final runway approach for optimal placement on the take-off board. PMID:29018542

  2. Analysis of altered complexity of gait dynamics with aging and Parkinson’s disease using ternary Lempel–Ziv complexity

    Directory of Open Access Journals (Sweden)

    Chandrakar Kamath

    2016-12-01

    Full Text Available Fluctuations in stride interval series show complex dynamical behavior in healthy young adults. Hypothesizing that these stride interval complexity changes would be altered by changes in neurological function associated with aging and certain disease states, we aimed to develop a tool to facilitate clinical judgments to assess the complex dynamical behavior in the stride series in discerning young, elderly, and Parkinson’s disease (PD classes. This novel approach, which employs a new variant of coarse-graining in conjunction with Lempel–Ziv complexity measure, yields useful, reliable, and predictive results. We also show the presence of nonlinear deterministic structures in the stride time series and appropriateness of the application of our nonlinear approach through surrogate data analysis. The findings show that the fluctuations are more complex/random in elderly and PD classes than those in young class. These findings may add to the growing body of literature supporting the clinical utility of this new approach to stride time series.

  3. Radio frequency modulation made easy

    CERN Document Server

    Faruque, Saleh

    2017-01-01

    This book introduces Radio Frequency Modulation to a broad audience. The author blends theory and practice to bring readers up-to-date in key concepts, underlying principles and practical applications of wireless communications. The presentation is designed to be easily accessible, minimizing mathematics and maximizing visuals.

  4. Low-frequency noise complaints

    DEFF Research Database (Denmark)

    Pedersen, Christian Sejer; Møller, Henrik; Persson-Waye, Kerstin

    2006-01-01

    is only heard by a single person in the household. This raises the fundamental question whether the complainants are annoyed by an external physical sound, or if other explanations such as low-frequency tinnitus must be sought. The main aim of this study is to answer this fundamental question...

  5. LOFAR- The Low Frequency Array

    NARCIS (Netherlands)

    Falcke, H.D.E.

    2006-01-01

    LOFAR is an innovative radio telescope in the frequency range of 10-240 MHz, realized as a phased array. It will become the largest radio telescope in the world in the time frame 2006-2010, located in Northern Europe. LOFAR is being implemented as a Wide Area Sensor Network which connects thousands

  6. High-frequency Trader Subjectivity

    DEFF Research Database (Denmark)

    Borch, Christian; Lange, Ann-Christina

    2017-01-01

    that although HFT does not render humans irrelevant, it is leading to a reconfiguration of both the ideal trading subject and the human–machine relations. Drawing on interviews with and ethnographic observations of high-frequency traders, as well as HFT ‘how to’ books, we analyze the subjectivity and self...

  7. Demand as Frequency Controlled Reserve

    DEFF Research Database (Denmark)

    Xu, Zhao; Togeby, Mikael; Østergaard, Jacob

    This report summaries the research outcomes of the project ‘Demand as Frequency Controlled Reserve (DFR)’, which has received the support from Energinet.dk’s PSO program, Grant no. 2005-2-6380. The objective of this project is to investigate the technology of using electricity demands for providing...

  8. Variation in female morph frequencies and mating frequencies : random, frequency-dependent harassment or male mimicry?

    NARCIS (Netherlands)

    Hammers, Martijn; Van Gossum, Hans

    2008-01-01

    Female-limited colour polymorphisms occur in a variety of species, where often one female morph (androchrome) resembles the body coloration of the conspecific male, whereas the other (gynochrome) does not. We tested predictions of two frequency-dependent hypotheses that are commonly invoked to

  9. High-Frequency Seafloor Acoustics

    CERN Document Server

    Jackson, Darrell R

    2007-01-01

    High-Frequency Seafloor Acoustics is the first book in a new series sponsored by the Office of Naval Research on the latest research in underwater acoustics. This exciting new title provides ready access to experimental data, theory, and models relevant to high-frequency seafloor acoustics and will be of interest to sonar engineers and researchers working in underwater acoustics. The physical characteristics of the seafloor affecting acoustic propagation and scattering are covered, including physical and geoacoustic properties and surface roughness. Current theories for acoustic propagation in sediments are presented along with corresponding models for reflection, scattering, and seafloor penetration. The main text is backed up by an extensive bibliography and technical appendices.

  10. Parsimonious nonstationary flood frequency analysis

    Science.gov (United States)

    Serago, Jake M.; Vogel, Richard M.

    2018-02-01

    There is now widespread awareness of the impact of anthropogenic influences on extreme floods (and droughts) and thus an increasing need for methods to account for such influences when estimating a frequency distribution. We introduce a parsimonious approach to nonstationary flood frequency analysis (NFFA) based on a bivariate regression equation which describes the relationship between annual maximum floods, x, and an exogenous variable which may explain the nonstationary behavior of x. The conditional mean, variance and skewness of both x and y = ln (x) are derived, and combined with numerous common probability distributions including the lognormal, generalized extreme value and log Pearson type III models, resulting in a very simple and general approach to NFFA. Our approach offers several advantages over existing approaches including: parsimony, ease of use, graphical display, prediction intervals, and opportunities for uncertainty analysis. We introduce nonstationary probability plots and document how such plots can be used to assess the improved goodness of fit associated with a NFFA.

  11. The radio-frequency quadrupole

    CERN Document Server

    Vretenar, Maurizio

    2013-01-01

    Radio-frequency quadrupole (RFQ) linear accelerators appeared on the accelerator scene in the late 1970s and have since revolutionized the domain of low-energy proton and ion acceleration. The RFQ makes the reliable production of unprecedented ion beam intensities possible within a compact radio-frequency (RF) resonator which concentrates the three main functions of the low-energy linac section: focusing, bunching and accelerating. Its sophisticated electrode structure and strict beam dynamics and RF requirements, however, impose severe constraints on the mechanical and RF layout, making the construction of RFQs particularly challenging. This lecture will introduce the main beam optics, RF and mechanical features of a RFQ emphasizing how these three aspects are interrelated and how they contribute to the final performance of the RFQ.

  12. Lossless equalization of frequency combs.

    Science.gov (United States)

    Torres-Company, Víctor; Lancis, Jesús; Andrés, Pedro

    2008-08-15

    Frequency combs obtained by sinusoidal phase modulation of narrowband cw lasers are widely used in the field of optical communications. However, the resulting spectral envelope of the comb is not flat. We propose a general and efficient approach to achieve flat frequency combs with tunable bandwidth. The idea is based on a two-step process. First, efficient generation of a train with a temporal flat-top-pulse profile is required. Second, we use large parabolic phase modulation in every train period to map the temporal intensity shape into the spectral domain. In this way the resulting spectral envelope is flat, and the size is tunable with the chirping rate. Two different schemes are proposed and verified through numerical simulations.

  13. High frequency power distribution system

    Science.gov (United States)

    Patel, Mikund R.

    1986-01-01

    The objective of this project was to provide the technology of high frequency, high power transmission lines to the 100 kW power range at 20 kHz frequency. In addition to the necessary design studies, a 150 m long, 600 V, 60 A transmission line was built, tested and delivered for full vacuum tests. The configuration analysis on five alternative configurations resulted in the final selection of the three parallel Litz straps configuration, which gave a virtually concentric design in the electromagnetic sense. Low inductance, low EMI and flexibility in handling are the key features of this configuration. The final design was made after a parametric study to minimize the losses, weight and inductance. The construction of the cable was completed with no major difficulties. The R,L,C parameters measured on the cable agreed well with the calculated values. The corona tests on insulation samples showed a safety factor of 3.

  14. Frequency scaling for angle gathers

    KAUST Repository

    Zuberi, M. A H

    2014-01-01

    Angle gathers provide an extra dimension to analyze the velocity after migration. Space-shift and time shift-imaging conditions are two methods used to obtain angle gathers, but both are reasonably expensive. By scaling the time-lag axis of the time-shifted images, the computational cost of the time shift imaging condition can be considerably reduced. In imaging and more so Full waveform inversion, frequencydomain Helmholtz solvers are used more often to solve for the wavefields than conventional time domain extrapolators. In such cases, we do not need to extend the image, instead we scale the frequency axis of the frequency domain image to obtain the angle gathers more efficiently. Application on synthetic data demonstrate such features.

  15. Meal frequency and childhood obesity.

    Science.gov (United States)

    Toschke, André M; Küchenhoff, Helmut; Koletzko, Berthold; von Kries, Rüdiger

    2005-11-01

    Previous studies have demonstrated an inverse association between meal frequency and the prevalence of obesity in adulthood. The aim of this study was to assess the relationship between meal frequency and childhood obesity. Stature and weight of 4,370 German children ages 5 to 6 years were determined in six Bavarian (Germany) public health offices during the obligatory school entry health examination in 2001/2002. An extensive questionnaire on risk factors for obesity was answered by their parents. Obesity was defined according to sex- and age-specific BMI cut-off points proposed by the International Obesity Task Force. The main exposure was daily meal frequency. The prevalence of obesity decreased by number of daily meals: three or fewer meals, 4.2% [95% confidence interval (CI), 2.8 to 6.1]; four meals, 2.8% (95% CI, 2.1 to 3.7); and 5 or more meals, 1.7% (95% CI, 1.2 to 2.4). These effects could not be explained by confounding due to a wide range of constitutional, sociodemographic, and lifestyle factors. The adjusted odds ratios for obesity were 0.73 (95% CI, 0.44 to 1.21) for four meals and 0.51 (95% CI, 0.29 to 0.89) for five or more meals. Additional analyses pointed to a higher energy intake in nibblers compared with gorgers. A protective effect of an increased daily meal frequency on obesity in children was observed and appeared to be independent of other risk factors for childhood obesity. A modulation of the response of hormones such as insulin might be instrumental.

  16. Frequency Diverse Array Receiver Architectures

    Science.gov (United States)

    2015-06-29

    currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 1. REPORT DATE (DD-MM-YYYY) 2. REPORT TYPE 3. DATES...flexible enough to include other frequency progressions or waveform types although not investigated in this thesis. Lastly, we present a technique...in Conjunction with MIMO Radar The FDA configuration discussed in the literature involves both the co-located and multi-static aper - ture arrangement

  17. LEP Radio Frequency Copper Cavity

    CERN Multimedia

    The pulse of a particle accelerator. 128 of these radio frequency cavities were positioned around CERN's 27-kilometre LEP ring to accelerate electrons and positrons. The acceleration was produced by microwave electric oscillations at 352 MHz. The electrons and positrons were grouped into bunches, like beads on a string, and the copper sphere at the top stored the microwave energy between the passage of individual bunches. This made for valuable energy savings as it reduced the heat generated in the cavity.

  18. Tracking frequency laser distance gauge

    International Nuclear Information System (INIS)

    Phillips, J.D.; Reasenberg, R.D.

    2005-01-01

    Advanced astronomical missions with greatly enhanced resolution and physics missions of unprecedented accuracy will require laser distance gauges of substantially improved performance. We describe a laser gauge, based on Pound-Drever-Hall locking, in which the optical frequency is adjusted to maintain an interferometer's null condition. This technique has been demonstrated with pm performance. Automatic fringe hopping allows it to track arbitrary distance changes. The instrument is intrinsically free of the nm-scale cyclic bias present in traditional (heterodyne) high-precision laser gauges. The output is a radio frequency, readily measured to sufficient accuracy. The laser gauge has operated in a resonant cavity, which improves precision, can suppress the effects of misalignments, and makes possible precise automatic alignment. The measurement of absolute distance requires little or no additional hardware, and has also been demonstrated. The proof-of-concept version, based on a stabilized HeNe laser and operating on a 0.5 m path, has achieved 10 pm precision with 0.1 s integration time, and 0.1 mm absolute distance accuracy. This version has also followed substantial distance changes as fast as 16 mm/s. We show that, if the precision in optical frequency is a fixed fraction of the linewidth, both incremental and absolute distance precision are independent of the distance measured. We discuss systematic error sources, and present plans for a new version of the gauge based on semiconductor lasers and fiber-coupled components

  19. Hyperbolic equations and frequency interactions

    CERN Document Server

    Caffarelli, Luis

    1998-01-01

    The research topic for this IAS/PCMI Summer Session was nonlinear wave phenomena. Mathematicians from the more theoretical areas of PDEs were brought together with those involved in applications. The goal was to share ideas, knowledge, and perspectives. How waves, or "frequencies", interact in nonlinear phenomena has been a central issue in many of the recent developments in pure and applied analysis. It is believed that wavelet theory-with its simultaneous localization in both physical and frequency space and its lacunarity-is and will be a fundamental new tool in the treatment of the phenomena. Included in this volume are write-ups of the "general methods and tools" courses held by Jeff Rauch and Ingrid Daubechies. Rauch's article discusses geometric optics as an asymptotic limit of high-frequency phenomena. He shows how nonlinear effects are reflected in the asymptotic theory. In the article "Harmonic Analysis, Wavelets and Applications" by Daubechies and Gilbert the main structure of the wavelet theory is...

  20. LOFAR, the low frequency array

    Science.gov (United States)

    Vermeulen, R. C.

    2012-09-01

    LOFAR, the Low Frequency Array, is a next-generation radio telescope designed by ASTRON, with antenna stations concentrated in the north of the Netherlands and currently spread into Germany, France, Sweden and the United Kingdom; plans for more LOFAR stations exist in several other countries. Utilizing a novel, phased-array design, LOFAR is optimized for the largely unexplored low frequency range between 30 and 240 MHz. Digital beam-forming techniques make the LOFAR system agile and allow for rapid re-pointing of the telescopes as well as the potential for multiple simultaneous observations. Processing (e.g. cross-correlation) takes place in the LOFAR BlueGene/P supercomputer, and associated post-processing facilities. With its dense core (inner few km) array and long (more than 1000 km) interferometric baselines, LOFAR reaches unparalleled sensitivity and resolution in the low frequency radio regime. The International LOFAR Telescope (ILT) is now issuing its first call for observing projects that will be peer reviewed and selected for observing starting in December. Part of the allocations will be made on the basis of a fully Open Skies policy; there are also reserved fractions assigned by national consortia in return for contributions from their country to the ILT. In this invited talk, the gradually expanding complement of operationally verified observing modes and capabilities are reviewed, and some of the exciting first astronomical results are presented.

  1. Fast frequency divider circuit using combinational logic

    Energy Technology Data Exchange (ETDEWEB)

    Helinski, Ryan

    2017-05-30

    The various technologies presented herein relate to performing on-chip frequency division of an operating frequency of a ring oscillator (RO). Per the various embodiments herein, a conflict between RO size versus operational frequency can be addressed by dividing the output frequency of the RO to a frequency that can be measured on-chip. A frequency divider circuit (comprising NOR gates and latches, for example) can be utilized in conjunction with the RO on the chip. In an embodiment, the frequency divider circuit can include a pair of latches coupled to the RO to facilitate dividing the oscillating frequency of the RO by 2. In another embodiment, the frequency divider circuit can include four latches (operating in pairs) coupled to the RO to facilitate dividing the oscillating frequency of the RO by 4. A plurality of ROs can be MUXed to the plurality of ROs by a single oscillation-counting circuit.

  2. CAMAC programmable-control frequency synthesizer

    International Nuclear Information System (INIS)

    Yumaguzin, T.Kh.; Vyazovkin, D.E.; Nazirov, Eh.P.; Tuktarov, R.F.

    1989-01-01

    Synthesizer allows to set frequency with 0.015% accuracy and to scan it with variable step. Frequency controlled divider with further summing-up of divided frequency with fundamental one is used in synthesizer, and it has allowed to use digit of the input code and to obtain 3-4 MHz frequency range. Variation of operation flowsheet in the other frequency range is possible. K-155 and K-531 series microcircuits were used during development

  3. Frequency Modulation of Spin-Transfer Oscillators

    OpenAIRE

    Pufall, M. R.; Rippard, W. H.; Kaka, S.; Silva, T. J.; Russek, S. E.

    2004-01-01

    Spin-polarized dc electric current flowing into a magnetic layer can induce precession of the magnetization at a frequency that depends on current. We show that addition of an ac current to this dc bias current results in a frequency modulated (FM) spectral output, generating sidebands spaced at the modulation frequency. The sideband amplitudes and shift of the center frequency with drive amplitude are in good agreement with a nonlinear FM model that takes into account the nonlinear frequency...

  4. Smartphone App-Based Assessment of Gait During Normal and Dual-Task Walking: Demonstration of Validity and Reliability.

    Science.gov (United States)

    Manor, Brad; Yu, Wanting; Zhu, Hao; Harrison, Rachel; Lo, On-Yee; Lipsitz, Lewis; Travison, Thomas; Pascual-Leone, Alvaro; Zhou, Junhong

    2018-01-30

    Walking is a complex cognitive motor task that is commonly completed while performing another task such as talking or making decisions. Gait assessments performed under normal and "dual-task" walking conditions thus provide important insights into health. Such assessments, however, are limited primarily to laboratory-based settings. The objective of our study was to create and test a smartphone-based assessment of normal and dual-task walking for use in nonlaboratory settings. We created an iPhone app that used the phone's motion sensors to record movements during walking under normal conditions and while performing a serial-subtraction dual task, with the phone placed in the user's pants pocket. The app provided the user with multimedia instructions before and during the assessment. Acquired data were automatically uploaded to a cloud-based server for offline analyses. A total of 14 healthy adults completed 2 laboratory visits separated by 1 week. On each visit, they used the app to complete three 45-second trials each of normal and dual-task walking. Kinematic data were collected with the app and a gold-standard-instrumented GAITRite mat. Participants also used the app to complete normal and dual-task walking trials within their homes on 3 separate days. Within laboratory-based trials, GAITRite-derived heel strikes and toe-offs of the phone-side leg aligned with smartphone acceleration extrema, following filtering and rotation to the earth coordinate system. We derived stride times-a clinically meaningful metric of locomotor control-from GAITRite and app data, for all strides occurring over the GAITRite mat. We calculated stride times and the dual-task cost to the average stride time (ie, percentage change from normal to dual-task conditions) from both measurement devices. We calculated similar metrics from home-based app data. For these trials, periods of potential turning were identified via custom-developed algorithms and omitted from stride-time analyses

  5. The relationship between attention and gait in aging: facts and fallacies.

    Science.gov (United States)

    Holtzer, Roee; Wang, Cuiling; Verghese, Joe

    2012-01-01

    The current study critically assessed the relationship between cognitive functions and gait in nondemented older adults. Quantitative measures of gait (velocity, cadence, and a coefficient of variance in stride length) were assessed in single and dual-task conditions. Three cognitive factors captured the domains of Executive Attention, Verbal IQ, and Memory. Linear regressions showed that Executive Attention was related to velocity in both walking conditions. However, Memory and Verbal IQ were also related to velocity. Memory was related to Cadence in both walking conditions. Executive Attention was related to the coefficient of variance in stride length in both walking conditions. Linear mixed effects models showed that dual-task costs were largest in velocity followed by cadence and the coefficient of variance in stride length. The relationship between cognitive functions and gait depends, in part, on the analytic approach used, gait parameters assessed, and walking condition.

  6. BIOMECHANICAL ANALYSIS OF RUNNING IN THE HIGH JUMP

    Directory of Open Access Journals (Sweden)

    Werlayne Leite

    2013-02-01

    Full Text Available The aim of this paper is to analyze the biomechanics of running at high jump. To this study was realized a bibliographic revision. The running phase is the one which starts when the athlete is set in movement for the jump until the moment that he touches the ground with the takeoff foot in front of the bar, this phase can be divided into two parts: the running in straight line and the running in curve. On the other hand, for better understanding and due to a biomechanical complexity, the running in curve will be divided into three other parts: the three last strides, the two last strides and the last strides. Besides that, we could mention important factors for an efficient approach run: the radius of the curve, the distance and length of the takeoff run.

  7. Limb dominance changes in walking evolution explored by asymmetric correlations in gait dynamics

    Science.gov (United States)

    Echeverria, Juan C.; Rodriguez, Eduardo; Velasco, Alejandra; Alvarez-Ramirez, Jose

    2010-04-01

    Fluctuations in the stride interval time series of unconstrained walking are not random but seem to exhibit long-range correlations that decay as a power law (Hausdorff et al. (1995) [35]). Here, we examine whether asymmetries are present in the long-range correlations of different gait parameters (stride, swing and stance intervals) for the left and right limbs. Gait dynamics corresponding to 16 healthy subjects were obtained from the Physionet database, which contains stride, stance and swing intervals for both left and right limbs. Detrended Fluctuation Analysis (DFA) revealed the presence of asymmetric long-range correlations in all gait cycle variables investigated. A rich variety of scaling exponent dynamics was found, with the presence of synchronicity, decreased correlations and dominant correlations. The results are discussed in terms of the hypothesis that reduced strength of long-range correlations reflect both enhanced stability and adaptability.

  8. Constraint-led changes in internal variability in running.

    Science.gov (United States)

    Haudum, Anita; Birklbauer, Jürgen; Kröll, Josef; Müller, Erich

    2012-01-01

    We investigated the effect of a one-time application of elastic constraints on movement-inherent variability during treadmill running. Eleven males ran two 35-min intervals while surface EMG was measured. In one of two 35-min intervals, after 10 min of running without tubes, elastic tubes (between hip and heels) were attached, followed by another 5 min of running without tubes. To assess variability, stride-to-stride iEMG variability was calculated. Significant increases in variability (36 % to 74 %) were observed during tube running, whereas running without tubes after the tube running block showed no significant differences. Results show that elastic tubes affect variability on a muscular level despite the constant environmental conditions and underline the nervous system's adaptability to cope with somehow unpredictable constraints since stride duration was unaltered.

  9. High-frequency magnetic components

    CERN Document Server

    Kazimierczuk, Marian K

    2013-01-01

    A unique text on the theory and design fundaments of inductors and transformers, updated with more coverage on the optimization of magnetic devices and many new design examples The first edition is popular among a very broad audience of readers in different areas of engineering and science. This book covers the theory and design techniques of the major types of high-frequency power inductors and transformers for a variety of applications, including switching-mode power supplies (SMPS) and resonant dc-to-ac power inverters and dc-to-dc power converters. It describes eddy-current phenomena (su

  10. Frequency Dependent Attenuation in Rocks

    Science.gov (United States)

    1990-01-20

    WORK UNIT ELEMENT NO NO NO ACCESSION NO 62714E 7A10 DA DA 1𔃻 T. ,E (Incude Security Clasification ) Frequency Dependent Attenuation in Rocks Ŗ 0E;SO’.A_...P., and L. Peselnick, Investigation of internal friction in fused quartz, steel , plexiglass, and Westerly granite from 0.01 to 1.00 Hertz at 10- to 10...P., and L. Peselnick, Investigation of internal friction in fused quartz, steel , plexiglas, and Westerly granite from 0.01 to 1.00 Hertz at 10-8 to 10

  11. Demand as Frequency Controlled Reserve

    DEFF Research Database (Denmark)

    Xu, Zhao; Østergaard, Jacob; Togeby, Mikael

    2011-01-01

    Relying on generation side alone is deemed insufficient to fulfill the system balancing needs for future Danish power system, where a 50% wind penetration is outlined by the government for year 2025. This paper investigates using the electricity demand as frequency controlled reserve (DFR) as a new...... balancing measure, which has a high potential and can provide many advantages. Firstly, the background of the research is reviewed, including conventional power system reserves and the electricity demand side potentials. Subsequently, the control logics and corresponding design considerations for the DFR...

  12. Optical transducers with frequency output

    Science.gov (United States)

    Osadchuk, Oleksandr V.; Osadchuk, Volodymyr S.; Osadchuk, Iaroslav O.; Kolimoldayev, Maksat; Komada, Paweł; Mussabekov, Kanat

    2017-08-01

    In this work the characteristics research of microelectronic transducers of optical radiation with a frequency output signal on the basis of a hybrid integrated circuit consisting of a bipolar and a field-effect transistor with a Schottky barrier is presented. The connection of an external inductance to electrodes a collector - drain allows to implement the auto generating device. The frequency of the device generation depends on power of optical radiation falling on photosensing elements as a photoresistor, photodiode and photosensing transistors switched on in a circuit of the self-excited oscillator. The impedance on electrodes the collector - drain of bipolar and field transistors has capacitive reactive part and negative active resistance, which compensates power losses in a tuning circuit of the device. On the base of a nonlinear equivalent circuit of the transducer on an alternating current the analytical expressions of function of transformation and equation of sensitivity are obtained. The sensitivity of optical transducers lays in a range from 25 kHz/μWt/cm2 up to 150 kHz/μWt/cm2.

  13. Robust laser frequency stabilization by serrodyne modulation.

    Science.gov (United States)

    Kohlhaas, Ralf; Vanderbruggen, Thomas; Bernon, Simon; Bertoldi, Andrea; Landragin, Arnaud; Bouyer, Philippe

    2012-03-15

    We report the relative frequency stabilization of a distributed feedback erbium-doped fiber laser on an optical cavity by serrodyne frequency shifting. A correction bandwidth of 2.3 MHz and a dynamic range of 220 MHz are achieved, which leads to a strong robustness against large disturbances up to high frequencies. We demonstrate that serrodyne frequency shifting reaches a higher correction bandwidth and lower relative frequency noise level compared to a standard acousto-optical modulator based scheme. Our results allow us to consider promising applications in the absolute frequency stabilization of lasers on optical cavities.

  14. Effect of Duration of Disease on Gait Parameters in Parkinson’s Patients

    Directory of Open Access Journals (Sweden)

    Aygün Özşahin

    2007-04-01

    Full Text Available OBJECTIVE: Posture and gait disturbances are major components which cause functional disability in Parkinson’s disease (PD. Three dimensional gait and motion analysis systems provide quantitative data of gait. OBJECTIVES: The aim of this study is to correlate between duration of disease and gait parameters of Parkinson patients during the on-phase. METHODS: We investigated temporospatial and kinematics variables of gait in 23 subjects with PD as measured in the on-phase of their medication cycle using motion analysis. We evaluated the correlation between all gait parameters and Gait and Balance Scale (GABS, unified Parkinson’s disease rating scale (UPDRS total-motor scores, Hoehn&Yahr (H&Y stages and duration of the disease. RESULTS: We found positive correlation between cadance and duration of disease. Patients had negative correlation between stride time and duration of disease. And also there was positive correlation between UPDRS total score and duration of disease. CONCLUSION: Increasing of cadance and decreasing of stride time exhibited by PD subjects is a compensatory mechanism for the difficulty in regulating stride lenght. It was reported that stride lenght control mediate by basal ganglia. Scaling of lower limb amplitude during locomotion can be controlled by higher levels of the Central Nervous System. Patients tend to increase pelvic rotation to keep their center of mass stabilised because of shortness of stride lenght. We thought that reduction pelvic and hip ROMs in coronal plane are impaired muscles of leg in the swing phase. These findings possibly indicate that shortness of stride lenght with the progression of disease is related to cortical centers. Three dimentional analysis systems provide detailed gait examination in PD patients to assess of progression and efficacy for therapies. Also, this method will guide us to explain physiopathologic mechanisms of PD

  15. Phase-dependent changes in local dynamic stability of human gait.

    Science.gov (United States)

    Ihlen, Espen A F; Goihl, Tobias; Wik, Per B; Sletvold, Olav; Helbostad, Jorunn; Vereijken, Beatrix

    2012-08-31

    Several methods derived from nonlinear time series analysis have been suggested to quantify stability in human gait kinematics. One of these methods is the definition of the maximum finite time Lyapunov exponent (λ) that quantifies how the system responds to infinitesimal perturbations. However, there are fundamental limitations to the conventional definition of λ for gait kinematics. First, exponential increase in initial perturbations cannot be assumed since real-life perturbations of gait kinematics are finite sized. Second, the transitions between single and double support phase within each stride cycle define two distinct dynamical regimes that may not be captured by a single λ. The present article presents a new method to quantify intra-stride changes λ(t) in local dynamical stability and employs the method to 3D lower extremity gait kinematics in 10 healthy adults walking on a treadmill at 3 different speeds. All participants showed an intra-stride change in λ(t) in the transition between single and double support phase. The intra-stride change reflected an both a increase and decrease in λ(t) at heel strike and toe off, respectively, with increased gait speed. Furthermore, a close relationship was found between the intra-stride change in standard deviation of foot velocity in the anterior-posterior direction and the intra-stride change of the initial perturbations. The present results indicate that local dynamical stability has gait phase-dependent changes that are not identified by conventional computation of a single λ. Copyright © 2012 Elsevier Ltd. All rights reserved.

  16. Classifying running speed conditions using a single wearable sensor: Optimal segmentation and feature extraction methods.

    Science.gov (United States)

    Benson, Lauren C; Clermont, Christian A; Osis, Sean T; Kobsar, Dylan; Ferber, Reed

    2018-04-11

    Accelerometers have been used to classify running patterns, but classification accuracy and computational load depends on signal segmentation and feature extraction. Stride-based segmentation relies on identifying gait events, a step avoided by using window-based segmentation. For each segment, discrete points can be extracted from the accelerometer signal, or advanced features can be computed. Therefore, the purpose of this study was to examine how different segmentation and feature extraction methods influence the accuracy and computational load of classifying running conditions. Forty-four runners ran at their preferred speed and 25% faster than preferred while an accelerometer at the lower back recorded 3D accelerations. Computational load was determined as the accelerometer signal was segmented into single and five strides, and corresponding small and large windows, with discrete points extracted from the single stride segments and advanced features computed from all four segment types. Each feature set was used to classify speed conditions and classification accuracy was recorded. Computational load and classification accuracy were compared across all feature sets using a repeated-measures MANOVA, with follow-up t-tests to compare feature type (discrete vs. advanced), segmentation method (stride- vs. window-based), and segment size (small vs. large), using a Bonferroni-adjusted α = 0.003. The five-stride (97.49 (±4.57)%) and large-window advanced (97.23 (±5.51)%) feature sets produced the greatest classification accuracy, but the large-window advanced feature set had a lower computational load (0.0041 (±0.0002)s) than the stride-based feature sets. Therefore, using a few advanced features and large overlapping window sizes yields the best performance of both classification accuracy and computational load. Copyright © 2018 Elsevier Ltd. All rights reserved.

  17. Differences in Lower Body Kinematics during Forward Treadmill Skating Between Two Different Hockey Skate Designs

    Directory of Open Access Journals (Sweden)

    Mike R. Hellyer

    2016-01-01

    Full Text Available Purpose: The purpose of this study was to investigate the differences in ankle flexibility and skating technique between a traditional hockey skate boot and a hockey skate boot with a flexible rear tendon guard. Skating technique was further investigated at different speeds to give insight on how skating technique alters as skating speed is increased. Methods: Eight elite hockey players were selected for the present study, which was conducted while skating on an Endless Ice Skating Treadmill.  Variables were recorded using a three-camera setup and measured from video records at five selected treadmill speeds using the Dartfish Team Pro v6 software.  Kinematic variables were then compared between the two skate designs with a doubly multivariate repeated measures design.  Statistical significance was set at p<0.05.  Results: Post hoc univariate tests comparing skate designs displayed significant increases in plantar flexion, plantar flexion angular velocity, hip extension, hip extension angular velocity, stride length, and stride velocity while participants were wearing the skates that had a flexible rear tendon guard.  Significant increases were also displayed in plantar flexion, plantar flexion angular velocity, knee extension, knee extension angular velocity, hip extension, hip extension angular velocity, hip abduction range of motion, hip abduction angular velocity, stride width, stride length, and stride velocity as the treadmill speed increased. There was also a significant decrease in the time the skate was in contact with the treadmill as treadmill speed increased. Conclusion: The results suggested that while skating forward, hockey players could improve their hockey skating technique by using hockey skates that have a flexible rear tendon guard.  This flexible tendon guard improved skating technique by increasing the time of force application to the ice by increasing the range of ankle plantar flexion during propulsion of the

  18. Animal galloping and human hopping: an energetics and biomechanics laboratory exercise.

    Science.gov (United States)

    Lindstedt, Stan L; Mineo, Patrick M; Schaeffer, Paul J

    2013-12-01

    This laboratory exercise demonstrates fundamental principles of mammalian locomotion. It provides opportunities to interrogate aspects of locomotion from biomechanics to energetics to body size scaling. It has the added benefit of having results with robust signal to noise so that students will have success even if not "meticulous" in attention to detail. First, using respirometry, students measure the energetic cost of hopping at a "preferred" hop frequency. This is followed by hopping at an imposed frequency half of the preferred. By measuring the O2 uptake and work done with each hop, students calculate mechanical efficiency. Lessons learned from this laboratory include 1) that the metabolic cost per hop at half of the preferred frequency is nearly double the cost at the preferred frequency; 2) that when a person is forced to hop at half of their preferred frequency, the mechanical efficiency is nearly that predicted for muscle but is much higher at the preferred frequency; 3) that the preferred hop frequency is strongly body size dependent; and 4) that the hop frequency of a human is nearly identical to the galloping frequency predicted for a quadruped of our size. Together, these exercises demonstrate that humans store and recover elastic recoil potential energy when hopping but that energetic savings are highly frequency dependent. This stride frequency is dependent on body size such that frequency is likely chosen to maximize this function. Finally, by requiring students to make quantitative solutions using appropriate units and dimensions of the physical variables, these exercises sharpen analytic and quantitative skills.

  19. Broadcast Communication by System Frequency Modulation

    DEFF Research Database (Denmark)

    Douglass, Philip James; You, Shi; Heussen, Kai

    2012-01-01

    Load controllers available today can measure AC system frequency and react to frequency deviations. A system operator can communicate to frequency sensitive loads by changing the set-points of the system’s dispatchable frequency regulation resources. Explicitly signaling system state by generating...... off-nominal system frequency values is a novel narrowband broadcast communications channel between system operators and frequency sensitive distributed energy resources (FS-DER). The feasibility of the proposed system is evaluated on an existing island power system in Denmark. This study shows...... that within standard frequency quality constraints, 4 distinct symbols are feasible on the island. However, the overarching imperative of system stability prevents the symbols from having arbitrary meanings. Higher frequency values must translate into greater consumption from loads, and vice versa. Within...

  20. Binaural beats and frequency-coding.

    Science.gov (United States)

    Fritze, W; Köhler, W

    1986-01-01

    Binaural beats were studied before and during a situation of temporary threshold shift, and no frequency shift could be found. In contrast, subjective binaural frequency comparison revealed a distinct shift. These findings demonstrate the two known modes of perception.

  1. Auditory adaptation improves tactile frequency perception

    NARCIS (Netherlands)

    Crommett, L.E.; Pérez Bellido, A.; Yau, J.M.

    2017-01-01

    Our ability to process temporal frequency information by touch underlies our capacity to perceive and discriminate surface textures. Auditory signals, which also provide extensive temporal frequency information, can systematically alter the perception of vibrations on the hand. How auditory signals

  2. Econometrics of financial high-frequency data

    CERN Document Server

    Hautsch, Nikolaus

    2011-01-01

    This book covers major approaches in high-frequency econometrics. It discusses implementation details, provides insights into properties of high-frequency data as well as institutional settings and presents applications.

  3. Lightweight, high-frequency transformers

    Science.gov (United States)

    Schwarze, G. E.

    1983-01-01

    The 25-kVA space transformer was developed under contract by Thermal Technology Laboratory, Buffalo, N. Y. The NASA Lewis transformer technology program attempted to develop the baseline technology. For the 25-kVA transformer the input voltage was chosen as 200 V, the output voltage as 1500 V, the input voltage waveform as square wave, the duty cycle as continuous, the frequency range (within certain constraints) as 10 to 40 kHz, the operating temperatures as 85 deg. and 130 C, the baseplate temperature as 50 C, the equivalent leakage inductance as less than 10 micro-h, the operating environment as space, and the life expectancy as 10 years. Such a transformer can also be used for aircraft, ship and terrestrial applications.

  4. Frequency domain optical parametric amplification.

    Science.gov (United States)

    Schmidt, Bruno E; Thiré, Nicolas; Boivin, Maxime; Laramée, Antoine; Poitras, François; Lebrun, Guy; Ozaki, Tsuneyuki; Ibrahim, Heide; Légaré, François

    2014-05-07

    Today's ultrafast lasers operate at the physical limits of optical materials to reach extreme performances. Amplification of single-cycle laser pulses with their corresponding octave-spanning spectra still remains a formidable challenge since the universal dilemma of gain narrowing sets limits for both real level pumped amplifiers as well as parametric amplifiers. We demonstrate that employing parametric amplification in the frequency domain rather than in time domain opens up new design opportunities for ultrafast laser science, with the potential to generate single-cycle multi-terawatt pulses. Fundamental restrictions arising from phase mismatch and damage threshold of nonlinear laser crystals are not only circumvented but also exploited to produce a synergy between increased seed spectrum and increased pump energy. This concept was successfully demonstrated by generating carrier envelope phase stable, 1.43 mJ two-cycle pulses at 1.8 μm wavelength.

  5. LOFAR- The Low Frequency Array

    Science.gov (United States)

    Falcke, H. D. E.

    2006-08-01

    LOFAR is an innovative radio telescope in the frequency range of 10-240 MHz, realized as a phased array. It will become the largest radio telescope in the world in the time frame 2006-2010, located in Northern Europe. LOFAR is being implemented as a Wide Area Sensor Network which connects thousands of cheap sensors spread throughout the country to a central super computer using an ultra-broadband, synchronized data network. As the central processor IBM has provided its Blue Gene/L supercomputer. It will process streaming data with about 0.5 Terabit per second. Many simple radio antennas connected to the network turn it into a huge radio telescope for cosmological studies. In addition, geophones will turn LOFAR into an earthquake monitoring system and infrasound and meteorology sensors will turn LOFAR into a real-time weather monitoring array for agricultural applications. LOFAR is the first radio telescopes that can listen to radio signals from the entire sky overhead, on all time scales, at a large range of frequencies, and even look back in time for a couple of seconds. The main strength of LOFAR are surveys. One goal is to detect the first generation of black holes and galaxies in the universe during the epoch of reionization and study hydrogen formed after the big bang. LOFAR is also an ideal system to discover transient and sporadic radio signals. Likely transient sources to be discovered with LOFAR are bursting stars and Jupiter-like planets, gamma-ray bursts, radio outbursts from black holes, but also lightning on Earth and even radio flashes from ultra-high energy cosmic particles hitting the Earth atmosphere. Some LOFAR prototypes have recently been built. They have produced the first instantaneous all-sky maps and discovered the radio emission from cosmic particle air showers.

  6. Coping with Radio Frequency Interference

    Science.gov (United States)

    Lewis, B. M.

    2009-01-01

    The radio spectrum is a finite resource, on which humanity makes many demands. And pressure on it is ever increasing with the development of new technology and ideas for radio services. After all, we all benefit from wifi and cell phones. Radio astronomers have a small percentage of the spectrum allocated to them at octave intervals in the metre-centimetre bands, and at important frequencies, such as that of the 21cm line of HI. Signals from other services, as well as from our own poorly-engineered equipment, sometimes contaminate our bands: these signals constitute RFI. These may totally obliterate the astronomical signal, or, in the case of CLOUDSAT, may be capable of completely destroying a receiver, which introduces us to the new possibility of 'destructive interference'. A geo-stationary satellite can block access to a piece of sky from one site. Good equipment design eliminates self-inflicted interference, while physical separation often provides adequate practical mitigation at many frequencies. However, new observatories end up being located in the West Australian desert or Antarctica. In future they may be on the back side of the Moon. But there is no Earth-bound protection via physical separation against satellite signals. Some mitigation can be achieved by frequent data dumps and the excision of RFI, or by real-time detection and blanking of the receiver, or by more sophisticated algoriths. Astronomers of necessity aim to achieve mitigation via coordination, at the local level, and by participating in spectrum management at the national and international levels. This involves them spending a lot of time in Geneva at the International Telegraphic Union protecting their access to spectrum, and access to clean spectrum from the L3 point and the far side of the Moon.

  7. New pulse modulator with low switching frequency

    Directory of Open Access Journals (Sweden)

    Golub V. S.

    2014-12-01

    Full Text Available The author presents an integrating pulse modulator (analog signal converter with the pulse frequency and duration modulation similar to sigma-delta modulation (with low switching frequency, without quantization. The modulator is characterized by the absence of the quantization noise inherent in sigma-delta modulator, and a low switching frequency, unlike the pulse-frequency modulator. The modulator is recommended, in particular, to convert signals at the input of the class D power amplifier.

  8. The use of relative coupling intervals in horses during walk

    DEFF Research Database (Denmark)

    Olsen, Emil; Pfau, Thilo

    force plates surrounded by a 12-camera Qualisys infrared kinematic system. Kinetic and kinematic data were collected synchronously at a sample rate of 200 Hz. Hoof-on was detected from kinetic data with a threshold of 10N. LCI is defined as the time from front hoof-on to the ipsilateral hind hoof......-on and DCI as front hoof-on to the contralateral hind hoof-on in the next stride. RLCI and RDCI are proportional changes in LCI and DCI between subsequent strides. Statistical analysis was performed using R and a linear mixed model with repeated measurements. No significant effect of speed was identified...

  9. Pronunciation Assessment in the Context of World Englishes

    DEFF Research Database (Denmark)

    Dimova, Slobodanka

    2017-01-01

    the Expanding Circle users, for which “phonological intelligibility” is the most important criterion (Jenkins, 2006a). The chapter will continue with a discussion of criticism of the current practices in language testing and assessment that claim that the field has failed to adopt the WE perspective...... accurately represent the domains of target language use (Elder & Harding, 2008). The chapter concludes that despite these constraints, strides have been made towards encompassing a WE perspective in test construction and task design, especially in listening and speaking tests, though the strides...

  10. Chrysanthemum biotechnology: discoveries from the recent literature

    Directory of Open Access Journals (Sweden)

    Teixeira da Silva Jaime A.

    2014-12-01

    Full Text Available The in vitro propagation of chrysanthemum (Chrysanthemum × grandiflorum (Ramat. Kitam., one of the world’s most important ornamentals, is a very well-studied topic and shows numerous strides each year. This mini-review condenses the knowledge that has been published on chrysanthemum biotechnology, especially in vitro culture in the wider plant science literature. In 2013 and 2014, important strides were made in molecular breeding, particularly anti-viral strategies, including through transgenics, and our understanding of flower genetics and flowering regulation.

  11. Validity and reliability of a portable gait analysis system for measuring spatiotemporal gait characteristics: comparison to an instrumented treadmill.

    Science.gov (United States)

    Donath, Lars; Faude, Oliver; Lichtenstein, Eric; Nüesch, Corina; Mündermann, Annegret

    2016-01-20

    Gait analysis serves as an important tool for clinicians and other health professionals to assess gait patterns related to functional limitations due to neurological or orthopedic conditions. The purpose of this study was to assess the validity of a body-worn inertial sensor system (RehaGait®) for measuring spatiotemporal gait characteristics compared to a stationary treadmill (Zebris) and the reliability of both systems at different walking speeds and slopes. Gait analysis was performed during treadmill walking at different speeds (habitual walking speed (normal speed); 15 % above normal walking speed; 15 % below normal walking speed) and slopes (0 % slope; 15 % slope) in 22 healthy participants twice 1 week apart. Walking speed, stride length, cadence and stride time were computed from the inertial sensor system and the stationary treadmill and compared using repeated measures analysis of variance. Effect sizes of differences between systems were assessed using Cohen's d, and limits of agreement and systematic bias were computed. The RehaGait® system slightly overestimated stride length (+2.7 %) and stride time (+0.8 %) and underestimate cadence (-1.5 %) with small effect sizes for all speeds and slopes (Cohen's d ≤ 0.44) except slow speed at 15 % slope (Cohen's d > 0.80). Walking speed obtained with the RehaGait® system closely matched the speed set on the treadmill tachometer. Intraclass correlation coefficients (ICC) were excellent for speed, cadence and stride time and for stride length at normal and fast speed at 0 % slope (ICC: .91-1.00). Good ICC values were found for stride length at slow speed at 0 % slope and all speeds at 15 % slope (ICC: .73-.90). Both devices had excellent reliability for most gait characteristics (ICC: .91-1.00) except good reliability for the RehaGait® for stride length at normal and fast speed at 0 % slope and at slow speed at 15 % slope (ICC: .80-.87). Larger limits of agreement for walking at 15

  12. 47 CFR 18.301 - Operating frequencies.

    Science.gov (United States)

    2010-10-01

    ... Standards § 18.301 Operating frequencies. ISM equipment may be operated on any frequency above 9 kHz except... allocated for use by ISM equipment: ISM frequency Tolerance 6.78 MHz ±15.0 kHz 13.56 MHz ±7.0 kHz 27.12 MHz...

  13. [Statistical analysis on andrological patients. I. Frequencies].

    Science.gov (United States)

    Nebe, K H; Schirren, C

    1980-01-01

    According a collective of 1619 andrological patients of the year 1975 some statistical data were given: age distribution, frequencies, frequency of sexual intercourse, anticonception and relation to age, coitus frequency and relation to age, impotence and relation to age, previous andrological treatment.

  14. On Frequency Combs in Monolithic Resonators

    Directory of Open Access Journals (Sweden)

    Savchenkov A. A.

    2016-06-01

    Full Text Available Optical frequency combs have become indispensable in astronomical measurements, biological fingerprinting, optical metrology, and radio frequency photonic signal generation. Recently demonstrated microring resonator-based Kerr frequency combs point the way towards chip scale optical frequency comb generator retaining major properties of the lab scale devices. This technique is promising for integrated miniature radiofrequency and microwave sources, atomic clocks, optical references and femtosecond pulse generators. Here we present Kerr frequency comb development in a historical perspective emphasizing its similarities and differences with other physical phenomena. We elucidate fundamental principles and describe practical implementations of Kerr comb oscillators, highlighting associated solved and unsolved problems.

  15. Exponential Frequency Spectrum in Magnetized Plasmas

    International Nuclear Information System (INIS)

    Pace, D. C.; Shi, M.; Maggs, J. E.; Morales, G. J.; Carter, T. A.

    2008-01-01

    Measurements of a magnetized plasma with a controlled electron temperature gradient show the development of a broadband spectrum of density and temperature fluctuations having an exponential frequency dependence at frequencies below the ion cyclotron frequency. The origin of the exponential frequency behavior is traced to temporal pulses of Lorentzian shape. Similar exponential frequency spectra are also found in limiter-edge plasma turbulence associated with blob transport. This finding suggests a universal feature of magnetized plasma turbulence leading to nondiffusive, cross-field transport, namely, the presence of Lorentzian shaped pulses

  16. Radio Frequency Power Load and Associated Method

    Science.gov (United States)

    Srinivasan, V. Karthik (Inventor); Freestone, Todd M. (Inventor); Sims, William Herbert, III (Inventor)

    2014-01-01

    A radio frequency power load and associated method. A radio frequency power load apparatus may include a container with an ionized fluid therein. The apparatus may include one conductor immersed in a fluid and another conductor electrically connected to the container. A radio frequency transmission system may include a radio frequency transmitter, a radio frequency amplifier connected to the transmitter and a radio frequency power load apparatus connected to the amplifier. The apparatus may include a fluid having an ion source therein, one conductor immersed in a fluid, and another conductor electrically connected to the container. A method of dissipating power generated by a radio frequency transmission system may include constructing a waveguide with ionized fluid in a container and connecting the waveguide to an amplifier of the transmission system.

  17. Primary Frequency Response with Aggregated DERs: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Guggilam, Swaroop S.; Dhople, Sairaj V.; Zhao, Changhong; Dall' Anese, Emiliano; Chen, Yu Christine

    2017-03-03

    Power networks have to withstand a variety of disturbances that affect system frequency, and the problem is compounded with the increasing integration of intermittent renewable generation. Following a large-signal generation or load disturbance, system frequency is arrested leveraging primary frequency control provided by governor action in synchronous generators. In this work, we propose a framework for distributed energy resources (DERs) deployed in distribution networks to provide (supplemental) primary frequency response. Particularly, we demonstrate how power-frequency droop slopes for individual DERs can be designed so that the distribution feeder presents a guaranteed frequency-regulation characteristic at the feeder head. Furthermore, the droop slopes are engineered such that injections of individual DERs conform to a well-defined fairness objective that does not penalize them for their location on the distribution feeder. Time-domain simulations for an illustrative network composed of a combined transmission network and distribution network with frequency-responsive DERs are provided to validate the approach.

  18. Liver calcifications: frequency and significance

    International Nuclear Information System (INIS)

    Bezerra, Alexandre Sergio de Araujo; D'Ippolito, Giuseppe; Martelli, Pierpaolo; Pinto, Gustavo Alfredo Duarte Henrique; Szejnfeld, Jacob; Galvao Filho, Mario Melo

    2003-01-01

    The purpose was to determine the frequency and etiology of intrahepatic calcifications diagnosed on abdominal computed tomography (CT) studies. A retrospective study of 1,362 consecutive CT scans of the abdomen was carried out to determine the presence of intrahepatic calcifications. The clinical and laboratorial data of all patients with liver calcifications were reviewed in order to establish the etiology of the lesions. The results showed that intrahepatic calcifications were found in 3.6% (49/1,362) of the patients, and were predominantly seen in women (57.2%) than in men (42.8%). The population age ranged from 18 to 92 years (mean 59.4 years; median 63.5 years). Calcifications were considered residual and without clinical repercussion in most cases (39/49; 79.5%) whereas in 14.4% (7/49) of the patients calcifications were associated with metastatic disease and in 6.1% (3/49) with cystic lesions. The primary tumors in the seven patients with calcified liver metastases were colon carcinoma (five patients), sarcoma (one patient) and malignant ovarian teratoma (one patient). Two of these patients presented calcifications only after chemotherapy. Conclusion: Intrahepatic calcifications are infrequent findings on routine abdominal CT scans (< 5%) and are mostly related to previous inflammatory and/or infectious diseases. (author)

  19. Visible-frequency hyperbolic metasurface

    Science.gov (United States)

    High, Alexander A.; Devlin, Robert C.; Dibos, Alan; Polking, Mark; Wild, Dominik S.; Perczel, Janos; de Leon, Nathalie P.; Lukin, Mikhail D.; Park, Hongkun

    2015-06-01

    Metamaterials are artificial optical media composed of sub-wavelength metallic and dielectric building blocks that feature optical phenomena not present in naturally occurring materials. Although they can serve as the basis for unique optical devices that mould the flow of light in unconventional ways, three-dimensional metamaterials suffer from extreme propagation losses. Two-dimensional metamaterials (metasurfaces) such as hyperbolic metasurfaces for propagating surface plasmon polaritons have the potential to alleviate this problem. Because the surface plasmon polaritons are guided at a metal-dielectric interface (rather than passing through metallic components), these hyperbolic metasurfaces have been predicted to suffer much lower propagation loss while still exhibiting optical phenomena akin to those in three-dimensional metamaterials. Moreover, because of their planar nature, these devices enable the construction of integrated metamaterial circuits as well as easy coupling with other optoelectronic elements. Here we report the experimental realization of a visible-frequency hyperbolic metasurface using single-crystal silver nanostructures defined by lithographic and etching techniques. The resulting devices display the characteristic properties of metamaterials, such as negative refraction and diffraction-free propagation, with device performance greatly exceeding those of previous demonstrations. Moreover, hyperbolic metasurfaces exhibit strong, dispersion-dependent spin-orbit coupling, enabling polarization- and wavelength-dependent routeing of surface plasmon polaritons and two-dimensional chiral optical components. These results open the door to realizing integrated optical meta-circuits, with wide-ranging applications in areas from imaging and sensing to quantum optics and quantum information science.

  20. High Temperature Radio Frequency Loads

    CERN Document Server

    Federmann, S; Grudiev, A; Montesinos, E; Syratchev, I

    2011-01-01

    In the context of energy saving and recovery requirements the design of reliable and robust RF power loads which permit a high outlet temperature and high pressure of the cooling water is desirable. Cooling water arriving at the outlet withmore than 150 ◦C and high pressure has a higher value than water with 50 ◦C under low pressure. Conventional RF power loads containing dielectric and magnetic materials as well as sensitive ceramic windows usually do not permit going much higher than 90 ◦C. Here we present and discuss several design concepts for "metal only" RF high power loads. One concept is the application of magnetic steel corrugated waveguides near cutoff – this concept could find practical use above several GHz. Another solution are resonant structures made of steel to be installed in large waveguides for frequencies of 500 MHz or lower. Similar resonant structures above 100 MHz taking advantage of the rather high losses of normal steel may also be used in coaxial line geometries with large di...

  1. Single-phase frequency converter

    Science.gov (United States)

    Baciu, I.; Cunţan, C. D.

    2017-01-01

    The paper presents a continuous voltage inverter - AC (12V / 230V) made with IGBT and two-stage voltage transformer. The sequence control transistors is achieved using a ring counter whose clock signal is obtained with a monostable circuit LM 555. The frequency of the clock signal can be adjustment with a potentiometer that modifies the charging current of the capacitor which causes constant monostable circuit time. Command sequence consists of 8 intervals of which 6 are assigned to command four transistors and two for the period break at the beginning and end of the sequence control. To obtain an alternation consisting of two different voltage level, two transistors will be comanded, connected to different windings of the transformer and the one connected to the winding providing lower voltage must be comanded twice. The output of the numerator goes through an inverter type MOS and a current amplifier with bipolar transistor.To achieve galvanic separation, an optocoupler will be used for each IGBT transistor, while protection is achieved with resistance and diode circuit. At the end there is connected an LC filter for smoothing voltage variations.

  2. Effect of high-frequency excitation on natural frequencies of spinning discs

    DEFF Research Database (Denmark)

    Hansen, Morten Hartvig

    2000-01-01

    The effect of high-frequency, non-resonant parametric excitation on the low-frequency response of spinning discs is considered. The parametric excitation is obtained through a non-constant rotation speed, where the frequency of the pulsating overlay is much higher than the lowest natural frequenc......The effect of high-frequency, non-resonant parametric excitation on the low-frequency response of spinning discs is considered. The parametric excitation is obtained through a non-constant rotation speed, where the frequency of the pulsating overlay is much higher than the lowest natural...

  3. Humans running in place on water at simulated reduced gravity.

    Directory of Open Access Journals (Sweden)

    Alberto E Minetti

    Full Text Available BACKGROUND: On Earth only a few legged species, such as water strider insects, some aquatic birds and lizards, can run on water. For most other species, including humans, this is precluded by body size and proportions, lack of appropriate appendages, and limited muscle power. However, if gravity is reduced to less than Earth's gravity, running on water should require less muscle power. Here we use a hydrodynamic model to predict the gravity levels at which humans should be able to run on water. We test these predictions in the laboratory using a reduced gravity simulator. METHODOLOGY/PRINCIPAL FINDINGS: We adapted a model equation, previously used by Glasheen and McMahon to explain the dynamics of Basilisk lizard, to predict the body mass, stride frequency and gravity necessary for a person to run on water. Progressive body-weight unloading of a person running in place on a wading pool confirmed the theoretical predictions that a person could run on water, at lunar (or lower gravity levels using relatively small rigid fins. Three-dimensional motion capture of reflective markers on major joint centers showed that humans, similarly to the Basilisk Lizard and to the Western Grebe, keep the head-trunk segment at a nearly constant height, despite the high stride frequency and the intensive locomotor effort. Trunk stabilization at a nearly constant height differentiates running on water from other, more usual human gaits. CONCLUSIONS/SIGNIFICANCE: The results showed that a hydrodynamic model of lizards running on water can also be applied to humans, despite the enormous difference in body size and morphology.

  4. Comparison of minimalist footwear strategies for simulating barefoot running: a randomized crossover study.

    Directory of Open Access Journals (Sweden)

    Karsten Hollander

    Full Text Available Possible benefits of barefoot running have been widely discussed in recent years. Uncertainty exists about which footwear strategy adequately simulates barefoot running kinematics. The objective of this study was to investigate the effects of athletic footwear with different minimalist strategies on running kinematics. Thirty-five distance runners (22 males, 13 females, 27.9 ± 6.2 years, 179.2 ± 8.4 cm, 73.4 ± 12.1 kg, 24.9 ± 10.9 km x week(-1 performed a treadmill protocol at three running velocities (2.22, 2.78 and 3.33 m x s(-1 using four footwear conditions: barefoot, uncushioned minimalist shoes, cushioned minimalist shoes, and standard running shoes. 3D kinematic analysis was performed to determine ankle and knee angles at initial foot-ground contact, rate of rear-foot strikes, stride frequency and step length. Ankle angle at foot strike, step length and stride frequency were significantly influenced by footwear conditions (p<0.001 at all running velocities. Posthoc pairwise comparisons showed significant differences (p<0.001 between running barefoot and all shod situations as well as between the uncushioned minimalistic shoe and both cushioned shoe conditions. The rate of rear-foot strikes was lowest during barefoot running (58.6% at 3.33 m x s(-1, followed by running with uncushioned minimalist shoes (62.9%, cushioned minimalist (88.6% and standard shoes (94.3%. Aside from showing the influence of shod conditions on running kinematics, this study helps to elucidate differences between footwear marked as minimalist shoes and their ability to mimic barefoot running adequately. These findings have implications on the use of footwear applied in future research debating the topic of barefoot or minimalist shoe running.

  5. Is Moderate Intensity Cycling Sufficient to Induce Cardiorespiratory and Biomechanical Modifications of Subsequent Running?

    Science.gov (United States)

    Walsh, Joel A; Dawber, James P; Lepers, Romuald; Brown, Marc; Stapley, Paul J

    2017-04-01

    Walsh, JA, Dawber, JP, Lepers, R, Brown, M, and Stapley, PJ. Is moderate intensity cycling sufficient to induce cardiorespiratory and biomechanical modifications of subsequent running? J Strength Cond Res 31(4): 1078-1086, 2017-This study sought to determine whether prior moderate intensity cycling is sufficient to influence the cardiorespiratory and biomechanical responses during subsequent running. Cardiorespiratory and biomechanical variables measured after moderate intensity cycling were compared with control running at the same intensity. Eight highly trained, competitive triathletes completed 2 separate exercise tests; (a) a 10-minute control run (no prior cycling) and, (b) a 30-minute transition run (TR) (preceded by 20-minute of variable cadence cycling, i.e., run versus cycle-run). Respiratory, breathing frequency (fb), heart rate (HR), cost of running (Cr), rate constant, stride length, and stride frequency variables were recorded, normalized, and quantified at the mean response time (MRT), third minute, 10th minute (steady state), and overall for the control run (CR) and TR. Cost of running increased (p ≤ 0.05) at all respective times during the TR. The V[Combining Dot Above]E/V[Combining Dot Above]CO2 and respiratory exchange ratio (RER) were significantly (p minute of the TR. Furthermore, overall mean increases were recorded for Cr, V[Combining Dot Above]E, V[Combining Dot Above]E/V[Combining Dot Above]CO2, RER, fb (p minutes (p cycling influences the cardiorespiratory response during subsequent running. Furthermore, prior cycling seems to have a sustained effect on the Cr during subsequent running.

  6. Fat King Penguins Are Less Steady on Their Feet.

    Science.gov (United States)

    Willener, Astrid S T; Handrich, Yves; Halsey, Lewis G; Strike, Siobhán

    2016-01-01

    Returning to the shore after a feeding sojourn at sea, king penguins often undertake a relatively long terrestrial journey to the breeding colony carrying a heavy, mostly frontal, accumulation of fat along with food in the stomach for chick-provisioning. There they must survive a fasting period of up to a month in duration, during which their complete reliance on endogenous energy stores results in a dramatic loss in body mass. Our aim was to determine if the king penguin's walking gait changes with variations in body mass. We investigated this by walking king penguins on a treadmill while instrumented with an acceleration data logger. The stride frequency, dynamic body acceleration (DBA) and posture of fat (pre-fasting; 13.2 kg) and slim (post fasting; 11 kg) king penguins were assessed while they walked at the same speed (1.4 km/h) on a treadmill. Paired statistical tests indicated no evidence for a difference in dynamic body acceleration or stride frequency between the two body masses however there was substantially less variability in both leaning angle and the leaning amplitude of the body when the birds were slimmer. Furthermore, there was some evidence that the slimmer birds exhibited a decrease in waddling amplitude. We suggest the increase in variability of both leaning angle and amplitude, as well as a possibly greater variability in the waddling amplitude, is likely to result from the frontal fat accumulation when the birds are heavier, which may move the centre of mass anteriorly, resulting in a less stable upright posture. This study is the first to use accelerometry to better understand the gait of a species within a specific ecological context: the considerable body mass change exhibited by king penguins.

  7. Electron heating mode transition induced by mixing radio frequency and ultrahigh frequency dual frequency powers in capacitive discharges

    International Nuclear Information System (INIS)

    Sahu, B. B.; Han, Jeon G.

    2016-01-01

    Electron heating mode transitions induced by mixing the low- and high-frequency power in dual-frequency nitrogen discharges at 400 mTorr pressure are presented. As the low-frequency (13.56 MHz) power decreases and high-frequency (320 MHz) power increases for the fixed power of 200 W, there is a transition of electron energy distribution function (EEDF) from Druyvesteyn to bi-Maxwellian type characterized by a distinguished warm electron population. It is shown that this EEDF evolution is attributed to the transition from collisional to collisionless stochastic heating of the low-energy electrons.

  8. Auditory filters at low-frequencies

    DEFF Research Database (Denmark)

    Orellana, Carlos Andrés Jurado; Pedersen, Christian Sejer; Møller, Henrik

    2009-01-01

    Hz. The notched-noise method was used, with the noise masker at 40 dB spectral density. A rounded exponential auditory filter model (roex(p,r)) was used to fit the masking data. Preliminary data on 1 subject is discussed. Considering the system as a whole (e.g. without removing the assumed middle......Prediction and assessment of low-frequency noise problems requires information about the auditory filter characteristics at low-frequencies. Unfortunately, data at low-frequencies is scarce and practically no results have been published for frequencies below 100 Hz. Extrapolation of ERB results...... was found to steadily decrease with decreasing center frequency. Although the observed decrease in filter bandwidth with decreasing center frequency was only approximately monotonic, the preliminary data indicates the filter bandwidth does not stabilize around 100 Hz, e.g. it still decreases below...

  9. Explaining the gender difference in nightmare frequency.

    Science.gov (United States)

    Schredl, Michael

    2014-01-01

    A recent meta-analysis showed a robust gender difference in nightmare frequency of medium effect size in adolescents and young adults: Women tend to report nightmares more frequently than men. The present study, carried out in an unselected student sample, indicates that 2 factors mediate the gender difference in nightmare frequency: neuroticism and overall dream recall frequency. The effect of neuroticism on the gender difference and the finding that the gender difference in nightmare frequency emerges at an age of about 10 years suggest that gender-specific socialization processes may play an important role in explaining the gender differences in nightmare frequency in adolescents and young to middle-aged adults. This idea is supported by the previous finding that nightmare frequency is related to sex role orientation. However, longitudinal studies are necessary to validate these hypotheses.

  10. Cluster analysis of word frequency dynamics

    Science.gov (United States)

    Maslennikova, Yu S.; Bochkarev, V. V.; Belashova, I. A.

    2015-01-01

    This paper describes the analysis and modelling of word usage frequency time series. During one of previous studies, an assumption was put forward that all word usage frequencies have uniform dynamics approaching the shape of a Gaussian function. This assumption can be checked using the frequency dictionaries of the Google Books Ngram database. This database includes 5.2 million books published between 1500 and 2008. The corpus contains over 500 billion words in American English, British English, French, German, Spanish, Russian, Hebrew, and Chinese. We clustered time series of word usage frequencies using a Kohonen neural network. The similarity between input vectors was estimated using several algorithms. As a result of the neural network training procedure, more than ten different forms of time series were found. They describe the dynamics of word usage frequencies from birth to death of individual words. Different groups of word forms were found to have different dynamics of word usage frequency variations.

  11. Cluster analysis of word frequency dynamics

    International Nuclear Information System (INIS)

    Maslennikova, Yu S; Bochkarev, V V; Belashova, I A

    2015-01-01

    This paper describes the analysis and modelling of word usage frequency time series. During one of previous studies, an assumption was put forward that all word usage frequencies have uniform dynamics approaching the shape of a Gaussian function. This assumption can be checked using the frequency dictionaries of the Google Books Ngram database. This database includes 5.2 million books published between 1500 and 2008. The corpus contains over 500 billion words in American English, British English, French, German, Spanish, Russian, Hebrew, and Chinese. We clustered time series of word usage frequencies using a Kohonen neural network. The similarity between input vectors was estimated using several algorithms. As a result of the neural network training procedure, more than ten different forms of time series were found. They describe the dynamics of word usage frequencies from birth to death of individual words. Different groups of word forms were found to have different dynamics of word usage frequency variations

  12. High Frequency Components Recovery in Music Signals

    Directory of Open Access Journals (Sweden)

    V. Sebesta

    1999-04-01

    Full Text Available A new technique is presented which improves the subjective quality of band-limited music by recovery of high frequency components. Sequences of harmonics are found in the band-limited signal and these sequences are expanded to the high frequency band to estimate the lost part of spectrum. High frequency signal is generated to match this estimation and is added to the band-limited signal.

  13. String Stretching, Frequency Modulation, and Banjo Clang

    OpenAIRE

    Politzer, David

    2014-01-01

    The banjo’s floating bridge, string break angle, and flexible drumhead all contribute to substantial audio range frequency modulation. From the world of electronic music synthesis, it is known that modulating higher frequency sounds with lower acoustic frequencies leads to metallic and bell-like tone. The mechanics of the banjo does just that quite naturally, modulating fundamentals and harmonics with the motion of the bridge. In technical terms, with a floating bridge, string stretching is f...

  14. REVIEW OF IMPROVEMENTS IN RADIO FREQUENCY PHOTONICS

    Science.gov (United States)

    2017-09-01

    AFRL-RY-WP-TR-2017-0156 REVIEW OF IMPROVEMENTS IN RADIO FREQUENCY PHOTONICS Preetpaul S. Devgan RF/EO Subsystems Branch Aerospace Components...TITLE AND SUBTITLE REVIEW OF IMPROVEMENTS IN RADIO FREQUENCY PHOTONICS 5a. CONTRACT NUMBER In-house 5b. GRANT NUMBER N/A 5c. PROGRAM ELEMENT NUMBER N/A...number 88ABW-2017-4071, Clearance Date 23 August 2017. Report contains color. 14. ABSTRACT Radio Frequency (RF) photonics can be used for multiple

  15. Design of Metamaterials for Microwave Frequencies

    Science.gov (United States)

    2008-10-09

    dispersion of permeability in zero external magnetic field can be seen above 2 GHz. This result indicates that this substituted barium ferrite is a good...mainly contributes to permeability in the high frequency range is smaller in permalloy composites than that in spinel ferrite composites. In addition...the spin resonance frequency of permalloy composites is higher than that in spinel ferrite composites. Thus, the resonance-type frequency dispersion

  16. Low-frequency sonophoresis: a review.

    Science.gov (United States)

    Mitragotri, Samir; Kost, Joseph

    2004-03-27

    Application of ultrasound enhances skin permeability to a variety of molecules (sonophoresis). The enhancement induced by ultrasound is particularly significant at low-frequencies (fsonophoresis). This review summarizes mechanisms and applications of low-frequency sonophoresis. In vitro, in vivo, as well as clinical studies demonstrating the effect of low-frequency ultrasound on transdermal drug delivery and glucose extraction are summarized. Mechanistic insights gained through a number of investigations are also reviewed. Finally, reports on the synergistic effect of low-frequency ultrasound with other enhancers including chemicals and iontophoresis are summarized.

  17. Loads as a Resource: Frequency Responsive Demand

    Energy Technology Data Exchange (ETDEWEB)

    Kalsi, Karanjit [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Lian, Jianming [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Marinovici, Laurentiu D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Elizondo, Marcelo A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Zhang, Wei [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Moya, Christian [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2014-10-08

    Frequency control plays an important role in preserving the power balance of a multi-machine power system. Generators modify their power output when a non-zero frequency deviation is presented in order to restore power balance across the network. However, with plans for large-scale penetration of renewable energy resources, performing primary frequency control using only supply-side resources becomes not only prohibitively expensive, but also technically difficult. Frequency control from the demand side or load control presents a novel and viable way for providing the desired frequency response. Loads can measure frequency locally and change their power consumption after a non-zero frequency deviation is presented in order to achieve power balance between generation and consumption. The specific objectives of this project are to: •Provide a framework to facilitate large-scale deployment of frequency responsive end-use devices •Systematically design decentralized frequency-based load control strategies for enhanced stability performance •Ensure applicability over wide range of operating conditions while accounting for unpredictable end-use behavior and physical device constraints •Test and validate control strategy using large-scale simulations and field demonstrations •Create a level-playing field for smart grid assets with conventional generators

  18. Clock frequency estimation under spontaneous emission

    Science.gov (United States)

    Qin, Xi-Zhou; Huang, Jia-Hao; Zhong, Hong-Hua; Lee, Chaohong

    2018-02-01

    We investigate the quantum dynamics of a driven two-level system under spontaneous emission and its application in clock frequency estimation. By using the Lindblad equation to describe the system, we analytically obtain its exact solutions, which show three different regimes: Rabi oscillation, damped oscillation, and overdamped decay. From the analytical solutions, we explore how the spontaneous emission affects the clock frequency estimation. We find that under a moderate spontaneous emission rate, the transition frequency can still be inferred from the Rabi oscillation. Our results enable potential practical applications in frequency measurement and quantum control under decoherence.

  19. Rod Driven Frequency Entrainment and Resonance Phenomena

    Directory of Open Access Journals (Sweden)

    Christina Salchow

    2016-08-01

    Full Text Available A controversy exists on photic driving in the human visual cortex evoked by intermittent photic stimulation. Frequency entrainment and resonance phenomena are reported for frequencies higher than 12 Hz in some studies while missing in others. We hypothesized that this might be due to different experimental conditions, since both high and low intensity light stimulation were used. However, most studies do not report radiometric measurements, which makes it impossible to categorize the stimulation according to photopic, mesopic, and scotopic vision. Low intensity light stimulation might lead to scotopic vision, where rod perception dominates. In this study, we investigated photic driving for rod-dominated visual input under scotopic conditions. Twelve healthy volunteers were stimulated with low intensity light flashes at 20 stimulation frequencies, leading to rod activation only. The frequencies were multiples of the individual alpha frequency (α of each volunteer in the range from 0.40–2.30*α. 306-channel whole head magnetoencephalography recordings were analyzed in time, frequency, and spatiotemporal domains with the Topographic Matching Pursuit algorithm. We found resonance phenomena and frequency entrainment for stimulations at or close to the individual alpha frequency (0.90–1.10*α and half of the alpha frequency (0.40–0.55*α. No signs of resonance and frequency entrainment phenomena were revealed around 2.00*α. Instead, on-responses at the beginning and off-responses at the end of each stimulation train were observed for the first time in a photic driving experiment at frequencies of 1.30–2.30*α, indicating that the flicker fusion threshold was reached. All results, the resonance and entrainment as well as the fusion effects, provide evidence for rod-dominated photic driving in the visual cortex.

  20. Generation of optical frequencies out of the frequency comb of a femtosecond laser for DWDM telecommunication

    International Nuclear Information System (INIS)

    Kim, Y-J; Chun, B J; Kim, Y; Hyun, S; Kim, S-W

    2010-01-01

    We exploit the frequency comb of a fs laser as the frequency ruler to generate reference optical frequencies for multi-channel DWDM (dense wavelength-division-multiplexing) telecommunication. Our fiber-based scheme of single-mode extraction enables on-demand generation of optical frequencies within the telecommunication band with an absolute frequency uncertainty of 9.1×10 -13 . The linewidth of extracted optical modes is less than 1 Hz, and the instability is measured 2.3×10 -15 at 10 s averaging. This outstanding performance of optical frequency generation would lead to a drastic improvement of the spectral efficiency for the next-generation DWDM telecommunication

  1. Linearly frequency-modulated pulsed single-frequency fiber laser at 1083 nm.

    Science.gov (United States)

    Zhang, Yuanfei; Yang, Changsheng; Li, Can; Feng, Zhouming; Xu, Shanhui; Deng, Huaqiu; Yang, Zhongmin

    2016-02-22

    A linearly frequency-modulated, actively Q-switched, single-frequency ring fiber laser based on injection seeding from an ultra-short cavity is demonstrated at 1083 nm. A piezoelectric transducer is employed to obtain linearly frequency-modulating performance and over 1.05 GHz frequency-tuning range is achieved with a modulating frequency reaching tens of kilohertz. A maximum peak power of the stable output pulse is over 3.83 W during frequency-modulating process. This type of pulsed fiber laser provides a promising candidate for coherent LIDAR in the measurement of thermosphere.

  2. Recent developments in time-frequency analysis

    CERN Document Server

    Loughlin, Patrick

    1998-01-01

    Recent Developments in Time-Frequency Analysis brings together in one place important contributions and up-to-date research results in this fast moving area. Recent Developments in Time-Frequency Analysis serves as an excellent reference, providing insight into some of the most challenging research issues in the field.

  3. Silicon-Chip-Based Optical Frequency Combs

    Science.gov (United States)

    2015-10-26

    microresonator,” Phys. Rev. Lett. 107, 063901 (2011). [54] H. Jung, et al., “Optical frequency comb generation from aluminum nitride microring resonator...supercontinuum generation in silicon nitride waveguides. 15. SUBJECT TERMS Nonlinear optics, parametric mixing, nanophotonics, optical frequency combs 16...Finally, we investigated comb generation via coherent supercontinuum generation in silicon nitride waveguides. Our research effort illustrates that the

  4. Audio Classification from Time-Frequency Texture

    OpenAIRE

    Yu, Guoshen; Slotine, Jean-Jacques

    2008-01-01

    Time-frequency representations of audio signals often resemble texture images. This paper derives a simple audio classification algorithm based on treating sound spectrograms as texture images. The algorithm is inspired by an earlier visual classification scheme particularly efficient at classifying textures. While solely based on time-frequency texture features, the algorithm achieves surprisingly good performance in musical instrument classification experiments.

  5. Direct Load Control by AC Frequency Modulation

    DEFF Research Database (Denmark)

    Douglass, Philip James; You, Shi

    2012-01-01

    Fine-grained under frequency load shedding called “demand as a frequency controlled reserve“ (DFCR) has been shown to be a promising method of providingfrequency regulation service from distributed loads [1]. Micro-grids with a large portion of intermittent renewable generation will benefit greatly...

  6. 47 CFR 80.1077 - Frequencies.

    Science.gov (United States)

    2010-10-01

    ... MARITIME SERVICES Global Maritime Distress and Safety System (GMDSS) General Provisions § 80.1077 Frequencies. The following table describes the frequencies used in the Global Maritime Distress and Safety... 9200-9500 MHz. Maritime safety information (MSI): International NAVTEX 518 kHz. 7 Warnings 490 kHz...

  7. An Approximate Bayesian Fundamental Frequency Estimator

    DEFF Research Database (Denmark)

    Nielsen, Jesper Kjær; Christensen, Mads Græsbøll; Jensen, Søren Holdt

    2012-01-01

    Joint fundamental frequency and model order estimation is an important problem in several applications such as speech and music processing. In this paper, we develop an approximate estimation algorithm of these quantities using Bayesian inference. The inference about the fundamental frequency...

  8. Instantaneous frequencies of a chaotic system

    Indian Academy of Sciences (India)

    Time–frequency analysis; wavelets; Hamiltonian systems. PACS Nos 05.45.-a; 32.80.Rm. 1. Introduction ... Aix-Marseille II et du Sud Toulon-Var. Laboratoire affilié `a la FRUMAM (FR 2291). ... time–frequency analysis of signals, of which the wavelet transform is but one exam- ple [2], form the corner-stone of our method.

  9. Smart Demand for Frequency Regulation: Experimental Results

    DEFF Research Database (Denmark)

    Douglass, Philip James; Garcia-Valle, Rodrigo; Nyeng, Preben

    2013-01-01

    , industrial pump loads and relay-controlled loads were tested as DFCR. The tests show that a population of refrigerators was able to deliver frequency reserves approximately equal to their average power consumption. Electric space heaters were able to provide frequency reserves of over 90% their maximum power...

  10. Determination of mating frequency by radiotracer technique

    International Nuclear Information System (INIS)

    Hamid Miah, M.A.

    1978-01-01

    Radioisotope ( 32 P) was used to study the frequency of mating of an insect. The radioactivity counts correlated positively with the number of matings. Radioactivity was also detected from the eggs and excised embryos. This work suggests that radioisotope like ( 32 P) may be conveninently used to detect virginity and mating frequency of female insects without killing them. (author)

  11. Dependence of synchronization frequency of Kuramoto oscillators ...

    Indian Academy of Sciences (India)

    journal of. December 2014 physics pp. 945–953. Dependence of synchronization frequency of Kuramoto oscillators on symmetry of intrinsic frequency in ring ... In this article, we study the difference between networks with sym- ... The dynamics of a general ith oscillator in a system of N Kuramoto oscillators is given as.

  12. Hydra A at Low Radio Frequencies

    National Research Council Canada - National Science Library

    Lane, W. M; Clarke, T. E; Taylor, G. B; Perley, R. A; Kassim, N. E

    2004-01-01

    We present new, low-frequency images of the powerful FR I radio galaxy Hydra A (3C 218). Images were made with the Very Large Array at frequencies of 1415, 330, and 74 MHz, with resolutions on the order of 20...

  13. Hippocampal theta frequency shifts and operant behaviour

    NARCIS (Netherlands)

    Lopes da Silva, F.H.; Kamp, A.

    1. 1. A shift of hippocampal dominant theta frequency to 6 c/sec has been demonstrated in the post-reward period in two dogs, which occurs consistently related in time to a well defined behavioural pattern in the course of an operant conditioning paradigm. 2. 2. The frequency shift was detected and

  14. Local frequency dependence in transcranial ultrasound transmission

    Energy Technology Data Exchange (ETDEWEB)

    White, P J; Clement, G T; Hynynen, K [Department of Radiology, Harvard Medical School, Brigham and Women' s Hospital, Boston, MA 02115 (United States)

    2006-05-07

    The development of large-aperture multiple-source transducer arrays for ultrasound transmission through the human skull has demonstrated the possibility of controlled and substantial acoustic energy delivery into the brain parenchyma without the necessitation of a craniotomy. The individual control of acoustic parameters from each ultrasound source allows for the correction of distortions arising from transmission through the skull bone and also opens up the possibility for electronic steering of the acoustic focus within the brain. In addition, the capability to adjust the frequency of insonation at different locations on the skull can have an effect on ultrasound transmission. To determine the efficacy and applicability of a multiple-frequency approach with such a device, this study examined the frequency dependence of ultrasound transmission in the range of 0.6-1.4 MHz through a series of 17 points on four ex vivo human skulls. Effects beyond those that are characteristic of frequency-dependent attenuation were examined. Using broadband pulses, it was shown that the reflected spectra from the skull revealed information regarding ultrasound transmission at specific frequencies. A multiple-frequency insonation with optimized frequencies over the entirety of five skull specimens was found to yield on average a temporally brief 230% increase in the transmitted intensity with an 88% decrease in time-averaged intensity transmission within the focal volume. This finding demonstrates a potential applicability of a multiple-frequency approach in transcranial ultrasound transmission.

  15. Y-STR frequency surveying method

    DEFF Research Database (Denmark)

    Willuweit, Sascha; Caliebe, Amke; Andersen, Mikkel Meyer

    2011-01-01

    Reasonable formalized methods to estimate the frequencies of DNA profiles generated from lineage markers have been proposed in the past years and were discussed in the forensic community. Recently, collections of population data on the frequencies of variations in Y chromosomal STR profiles have ...

  16. Instantaneous frequencies of a chaotic system

    Indian Academy of Sciences (India)

    fined as ridges of the time–frequency landscape. Using the wavelet transform of a single trajectory, it can characterize key dynamical properties like the extent of chaos, resonance transitions and trappings. Keywords. Time–frequency analysis; wavelets; Hamiltonian systems. PACS Nos 05.45.-a; 32.80.Rm. 1. Introduction.

  17. Fast Hopping Frequency Generation in Digital CMOS

    CERN Document Server

    Farazian, Mohammad; Gudem, Prasad S

    2013-01-01

    Overcoming the agility limitations of conventional frequency synthesizers in multi-band OFDM ultra wideband is a key research goal in digital technology. This volume outlines a frequency plan that can generate all the required frequencies from a single fixed frequency, able to implement center frequencies with no more than two levels of SSB mixing. It recognizes the need for future synthesizers to bypass on-chip inductors and operate at low voltages to enable the increased integration and efficiency of networked appliances. The author examines in depth the architecture of the dividers that generate the necessary frequencies from a single base frequency and are capable of establishing a fractional division ratio.   Presenting the first CMOS inductorless single PLL 14-band frequency synthesizer for MB-OFDMUWB makes this volume a key addition to the literature, and with the synthesizer capable of arbitrary band-hopping in less than two nanoseconds, it operates well within the desired range on a 1.2-volt power s...

  18. Analytic clock frequency selection for global DVFS

    NARCIS (Netherlands)

    Gerards, Marco Egbertus Theodorus; Hurink, Johann L.; Holzenspies, P.K.F.; Kuper, Jan; Smit, Gerardus Johannes Maria

    2014-01-01

    Computers can reduce their power consumption by decreasing their speed using Dynamic Voltage and Frequency Scaling (DVFS). A form of DVFS for multicore processors is global DVFS, where the voltage and clock frequency is shared among all processor cores. Because global DVFS is efficient and cheap to

  19. Realization of Thermal Inertia in Frequency Domain

    Directory of Open Access Journals (Sweden)

    Boe-Shong Hong

    2014-02-01

    Full Text Available To realize the lagging behavior in heat conduction observed in these two decades, this paper firstly theoretically excludes the possibility that the underlying thermal inertia is a result of the time delay in heat diffusion. Instead, we verify in experiments the electro-thermal analogy, wherein the thermal inertial is parameterized by thermal inductance that formulates hyperbolic heat-conduction. The thermal hyperbolicity exhibits a special frequency response in Bode plot, wherein the amplitude ratios is kept flat after crossing some certain frequency, as opposed to Fourier heat-conduction. We apply this specialty to design an instrument that reliably identifies thermal inductances of some materials in frequency domain. The instrument is embedded with a DSP-based frequency synthesizer capable of modulating frequencies in utmost high-resolution. Thermal inertia implies a new possibility for energy storage in analogy to inductive energy storage in electricity or mechanics.

  20. Observation of Frequency Locked Coherent Transition Radiation

    CERN Document Server

    Marsh, Roark A; Temkin, Richard J

    2005-01-01

    Measurements of frequency locked, coherent transition radiation (CTR) were performed at the 17 GHz high-gradient accelerator facility built by Haimson Research Corporation at MIT PSFC. CTR produced from a metallic foil placed in the beam path was extracted through a window, and measured with a variety of detectors, including: diode, Helium cooled Si Bolometer, and double heterodyne receiver system. The angular energy distribution measured by the diode and bolometer are in agreement and consistent with calculations for a 15 MeV 200 mA 110 ns beam of 1 ps bunches. Heterodyne receiver measurements were able to show frequency locking, namely inter-bunch coherence at integer multiples of the accelerator RF frequency of 17.14 GHz. At the locked frequencies the power levels are enhanced by the number of bunches in a single beam pulse. The CTR was measured as a comb of locked frequencies up to 240 GHz, with a bandwidth of 50 MHz.

  1. Slot Machine Response Frequency Predicts Pathological Gambling

    DEFF Research Database (Denmark)

    Linnet, Jakob; Rømer Thomsen, Kristine; Møller, Arne

    2013-01-01

    ) on slot machines compared with non-problem gamblers, which may suggest increased reinforcement of the gambling behavior in pathological gambling. However, to date it is unknown whether or not the increased response frequency in pathological gambling is associated with symptom severity of the disorder....... This study tested the hypothesis that response frequency is associated with symptom severity in pathological gambling. We tested response frequency among twenty-two pathological gambling sufferers and twenty-one non-problem gamblers on a commercially available slot machine, and screened for pathological...... gambling symptom severity using the South Oaks Gambling Screen (SOGS). The results showed that pathological gambling sufferers had significantly higher response frequency than non-problem gamblers, and that response frequency was significantly correlated with SOGS symptom severity among pathological...

  2. Y-STR frequency surveying method

    DEFF Research Database (Denmark)

    Willuweit, Sascha; Caliebe, Amke; Andersen, Mikkel Meyer

    2011-01-01

    reached a new quality with the establishment of the comprehensive neatly quality-controlled reference database YHRD. Grounded on such unrivalled empirical material from hundreds of populations studies the core assumption of the Haplotype Frequency Surveying Method originally described 10 years ago can...... be tested and improved. Here we provide new approaches to calculate the parameters used in the frequency surveying method: a maximum likelihood estimation of the regression parameters (r1, r2, s1 and s2) and a revised Frequency Surveying framework with variable binning and a database preprocessing to take......Reasonable formalized methods to estimate the frequencies of DNA profiles generated from lineage markers have been proposed in the past years and were discussed in the forensic community. Recently, collections of population data on the frequencies of variations in Y chromosomal STR profiles have...

  3. High frequency oscillations in brain hemodynamic response

    Science.gov (United States)

    Akin, Ata; Bolay, Hayrunnisa

    2007-07-01

    Tight autoregulation of vessel tone guarantees proper delivery of nutrients to the tissues. This regulation is maintained at a more delicate level in the brain since any decrease in the supply of glucose and oxygen to neuronal tissues might lead to unrecoverable injury. Functional near infrared spectroscopy has been proposed as a new tool to monitor the cerebrovascular response during cognitive activity. We have observed that during a Stroop task three distinct oscillatory patterns govern the control of the cerebrovascular reactivity: very low frequency (0.02-0.05 Hz), low frequency (0.08-0.12 Hz) and high frequency (0.12-0.18 Hz). High frequency oscillations have been shown to be related to stress level of the subjects. Our findings indicate that as the stress level is increased so does the energy of the high frequency component indicating a higher stimulation from the autonomic nervous system.

  4. Frequency interactions in human epileptic brain.

    Science.gov (United States)

    Cotic, Marija; Zalay, Osbert; Valiante, Taufik; Carlen, Peter L; Bardakjian, Berj L

    2011-01-01

    We have used two algorithms, wavelet phase coherence (WPC) and modulation index (MI) analysis to study frequency interactions in the human epileptic brain. Quantitative analyses were performed on intracranial electroencephalographic (iEEG) segments from three patients with neocortical epilepsy. Interelectrode coherence was measured using WPC and intraelectrode frequency interactions were analyzed using MI. WPC was performed on electrode pairings and the temporal evolution of phase couplings in the following frequency ranges: 1-4 Hz, 4-8 Hz, 8-13 Hz, 13-30 Hz and 30-100 Hz was studied. WPC was strongest in the 1-4 Hz frequency range during both seizure and non-seizure activities; however, WPC values varied minimally between electrode pairings. The 13-30 Hz band showed the lowest WPC values during seizure activity. MI analysis yielded two prominent patterns of frequency-specific activity, during seizure and non-seizure activities, which were present across all patients.

  5. Effective masking bandwidths at low frequencies.

    Science.gov (United States)

    Fidell, S; Horonjeff, R; Teffeteller, S; Green, D M

    1983-02-01

    Masking of low-frequency sinusoids of varying durations by Gaussian noise of varying spectral shape was measured in three different studies. Common solutions to technical problems associated with control and specification of low-frequency signals were used in the three studies. If interpreted in terms of Fletcher's critical ratio assumptions, data from the first study lead to the inference that the masking bandwidth is inversely related to signal frequency below about 200 Hz. Data from the second study rule out the likelihood that the apparent increase in masking bandwidth is attributable to changes in auditory integration times at low frequencies. The data of the third study suggest that the apparent increase in auditory filter bandwidth at low frequencies is more adequately explained by a decrease in observers' detection efficiency than by broadening of the filter bandpass.

  6. Time-Frequency, Bi-Frequency Detection Analysis of Noise Technology Radar

    National Research Council Canada - National Science Library

    Heuschel, Eugene R

    2006-01-01

    .... This thesis examines the use of time-frequency, bi-frequency signal detection techniques to identify the parameters of the four types of continuous waveform noise radar recently reported. These include: (a) random noise, (b...

  7. Frequency-Locked Single-Frequency Fiber Laser at 2 Micron, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Frequency-locked single-frequency 2 micron fiber laser is proposed to be used for airborne/spaceborne coherent lidar measurements, i.e., Active Sensing of CO2...

  8. A New Frequency Partitioning and Allocation of Subcarriers for Fractional Frequency Reuse in Mobile Communication Systems

    Science.gov (United States)

    Han, Seung Su; Park, Jongho; Lee, Tae-Jin; Ahn, Hyun Gi; Jang, Kyunghun

    Some OFDMA-based wireless commuication systems, e. g., Wireless Broadband Internet (WiBro) or Worldwide interoperability for Microwave Access (WiMAX), support frequency reuse of 1 to maximize spectral efficiency. One of the efficient methods to reduce co-channel interference (CCI) caused by frequency reuse is fractional frequency reuse (FFR). In this paper, we propose and validate a novel frequency partitioning method and subcarrier assignment mechanism to improve system and individual capacity of mobile systems using FFR.

  9. Meal frequencies in early adolescence predict meal frequencies in late adolescence and early adulthood

    DEFF Research Database (Denmark)

    Pedersen, Trine Pagh; Holstein, Bjørn E; Flachs, Esben Meulengracht

    2013-01-01

    Health and risk behaviours tend to be maintained from adolescence into adulthood. There is little knowledge on whether meal frequencies in adolescence are maintained into adulthood. We investigated whether breakfast, lunch and evening meal frequencies in early adolescence predicted meal frequencies...... in late adolescence and in early adulthood. Further, the modifying effect of gender and adolescent family structure were investigated....

  10. Frequency adjustable MEMS vibration energy harvester

    Science.gov (United States)

    Podder, P.; Constantinou, P.; Amann, A.; Roy, S.

    2016-10-01

    Ambient mechanical vibrations offer an attractive solution for powering the wireless sensor nodes of the emerging “Internet-of-Things”. However, the wide-ranging variability of the ambient vibration frequencies pose a significant challenge to the efficient transduction of vibration into usable electrical energy. This work reports the development of a MEMS electromagnetic vibration energy harvester where the resonance frequency of the oscillator can be adjusted or tuned to adapt to the ambient vibrational frequency. Micro-fabricated silicon spring and double layer planar micro-coils along with sintered NdFeB micro-magnets are used to construct the electromagnetic transduction mechanism. Furthermore, another NdFeB magnet is adjustably assembled to induce variable magnetic interaction with the transducing magnet, leading to significant change in the spring stiffness and resonance frequency. Finite element analysis and numerical simulations exhibit substantial frequency tuning range (25% of natural resonance frequency) by appropriate adjustment of the repulsive magnetic interaction between the tuning and transducing magnet pair. This demonstrated method of frequency adjustment or tuning have potential applications in other MEMS vibration energy harvesters and micromechanical oscillators.

  11. Frequency adjustable MEMS vibration energy harvester

    International Nuclear Information System (INIS)

    Podder, P; Constantinou, P; Roy, S; Amann, A

    2016-01-01

    Ambient mechanical vibrations offer an attractive solution for powering the wireless sensor nodes of the emerging “Internet-of-Things”. However, the wide-ranging variability of the ambient vibration frequencies pose a significant challenge to the efficient transduction of vibration into usable electrical energy. This work reports the development of a MEMS electromagnetic vibration energy harvester where the resonance frequency of the oscillator can be adjusted or tuned to adapt to the ambient vibrational frequency. Micro-fabricated silicon spring and double layer planar micro-coils along with sintered NdFeB micro-magnets are used to construct the electromagnetic transduction mechanism. Furthermore, another NdFeB magnet is adjustably assembled to induce variable magnetic interaction with the transducing magnet, leading to significant change in the spring stiffness and resonance frequency. Finite element analysis and numerical simulations exhibit substantial frequency tuning range (25% of natural resonance frequency) by appropriate adjustment of the repulsive magnetic interaction between the tuning and transducing magnet pair. This demonstrated method of frequency adjustment or tuning have potential applications in other MEMS vibration energy harvesters and micromechanical oscillators. (paper)

  12. Frequency Approach to Analysis of ESD Pulse

    Science.gov (United States)

    Baran, Janusz; Sroka, Jan

    The paper concerns calibration of generators for simulation of the Human-Metal Electrostatic Discharge (ESD) according to the IEC 61000-4-2 standard. It is shown that analysis of the ESD pulse in the frequency domain can be an indication if omitting the frequency considerations in calibration of ESD guns is acceptable. The calibration setup consists of a target (current converter), attenuator, coaxial cable and a wideband, single shot oscilloscope. It is much easier to use only a low frequency model of such a measurement path setup than consider a high frequency model. If, however, a high frequency treatment is indispensable, then a frequency dependent transfer impedance of the measurement path and approximation of the oscilloscope frequency response with an infinite impulse response discrete time filter are adequate tools. Comparison of power spectral densities (PSD) of theoretical pulses, measured pulses as well as the measurement path noise gives a good criterion for specifying minimal bandwidth of a setup required for reliable calibration of a given ESD gun. This paper is a resume of previous papers of the authors, in which these issues were presented in details.

  13. Memory for frequency of hearing popular songs.

    Science.gov (United States)

    Fidler, J R; Zechmeister, E B; Shaughnessy, J J

    1988-01-01

    In two experiments college students were asked to provide situational frequency estimates of 10-s excerpts from rock songs. In both experiments familiarity of the musical selections heard one, two, three, or four times was varied. In Experiment 2 the nature of instructions given to subjects prior to presentation of the musical excerpts was also manipulated. Across both experiments subjects' estimates were less accurate for unfamiliar than for familiar rock music. In Experiment 2 instructions to remember frequency, as well as general memory instructions, resulted in better memory for presentation frequency than did instructions to "ignore" music while working on math problems. Memory for situational frequency was also related to knowledge of rock music as defined by subjects' ability to identify the titles and artists of the presented songs. The present pattern of results with popular music is viewed as similar to that obtained in experiments investigating memory for frequency of verbal stimuli. Although providing support for an automatic processing view of frequency encoding, the results also implicate meaningful elaboration of stimuli as an important determinant of memory for frequency of events.

  14. Frequency domain image filtering using cuda

    International Nuclear Information System (INIS)

    Rajput, M.A.; Khan, U.A.

    2014-01-01

    In this paper, we investigate the implementation of image filtering in frequency domain using NVIDIA's CUDA (Compute Unified Device Architecture). In contrast to signal and image filtering in spatial domain which uses convolution operations and hence is more compute-intensive for filters having larger spatial extent, the frequency domain filtering uses FFT (Fast Fourier Transform) which is much faster and significantly reduces the computational complexity of the filtering. We implement the frequency domain filtering on CPU and GPU respectively and analyze the speed-up obtained from the CUDA's parallel processing paradigm. In order to demonstrate the efficiency of frequency domain filtering on CUDA, we implement three frequency domain filters, i.e., Butter worth, low-pass and Gaussian for processing different sizes of images on CPU and GPU respectively and perform the GPU vs. CPU benchmarks. The results presented in this paper show that the frequency domain filtering with CUDA achieves significant speed-up over the CPU processing in frequency domain with the same level of (output) image quality on both the processing architectures. (author)

  15. Frequency Domain Image Filtering Using CUDA

    Directory of Open Access Journals (Sweden)

    Muhammad Awais Rajput

    2014-10-01

    Full Text Available In this paper, we investigate the implementation of image filtering in frequency domain using NVIDIA?s CUDA (Compute Unified Device Architecture. In contrast to signal and image filtering in spatial domain which uses convolution operations and hence is more compute-intensive for filters having larger spatial extent, the frequency domain filtering uses FFT (Fast Fourier Transform which is much faster and significantly reduces the computational complexity of the filtering. We implement the frequency domain filtering on CPU and GPU respectively and analyze the speed-up obtained from the CUDA?s parallel processing paradigm. In order to demonstrate the efficiency of frequency domain filtering on CUDA, we implement three frequency domain filters, i.e., Butterworth, low-pass and Gaussian for processing different sizes of images on CPU and GPU respectively and perform the GPU vs. CPU benchmarks. The results presented in this paper show that the frequency domain filtering with CUDA achieves significant speed-up over the CPU processing in frequency domain with the same level of (output image quality on both the processing architectures

  16. Effect of Muscle-Damaging Eccentric Exercise on Running Kinematics and Economy for Running at Different Intensities.

    Science.gov (United States)

    Satkunskienė, Danguolė; Stasiulis, Arvydas; Zaičenkovienė, Kristina; Sakalauskaitė, Raminta; Rauktys, Donatas

    2015-09-01

    The objective of this study was to explore the changes in running kinematics and economy during running at different intensities 1 and 24 hours after a muscle-damaging bench-stepping exercise. Healthy, physically active adult women were recruited for this study. The subjects' running kinematics, heart rate, gas exchange, minute ventilation, and perceived exertion were continuously recorded during the increasing-intensity running test on a treadmill for different testing conditions: a control condition and 1 and 24 hours after the bench-stepping exercise test. Two muscle damage markers, muscle soreness and blood creatine kinase (CK) activity, were measured before and 24 hours after the stepping exercise. Muscle soreness and blood CK activity were significantly altered (exact p ≤ 0.05, Monte Carlo test) 24 hours after the bench-stepping exercise. The stride length, stride frequency, and support time at different running intensities did not change. Twenty-four hours after the previous step exercise, ankle dorsiflexion in the support phase was significantly higher during severe-intensity running, the range of knee flexion at the stance phase was significantly lower during moderate-intensity running, and knee flexion at the end of the amortization phase was significantly lower during heavy-intensity running compared with the control values (exact p ≤ 0.05, Monte Carlo test). The running economy at moderate and heavy intensities, maximum ventilation, and maximum heart rate did not change. We conclude that, given moderate soreness in the calf muscles 24 hours after eccentric exercise, the running kinematics are slightly but significantly changed without a detectable effect on running economy.

  17. Daily-Life Gait Quality as Predictor of Falls in Older People: A 1-Year Prospective Cohort Study.

    Directory of Open Access Journals (Sweden)

    Kimberley S van Schooten

    Full Text Available Falls can have devastating consequences for older people. We determined the relationship between the likelihood of fall incidents and daily-life behavior. We used wearable sensors to assess habitual physical activity and daily-life gait quality (in terms of e.g. stability, variability, smoothness and symmetry, and determined their predictive ability for time-to-first-and-second-falls. 319 older people wore a trunk accelerometer (Dynaport MoveMonitor, McRoberts during one week. Participants further completed questionnaires and performed grip strength and trail making tests to identify risk factors for falls. Their prospective fall incidence was followed up for six to twelve months. We determined interrelations between commonly used gait characteristics to gain insight in their interpretation and determined their association with time-to-falls. For all data -including questionnaires and tests- we determined the corresponding principal components and studied their predictive ability for falls. We showed that gait characteristics of walking speed, stride length, stride frequency, intensity, variability, smoothness, symmetry and complexity were often moderately to highly correlated (r > 0.4. We further showed that these characteristics were predictive of falls. Principal components dominated by history of falls, alcohol consumption, gait quality and muscle strength proved predictive for time-to-fall. The cross-validated prediction models had adequate to high accuracy (time dependent AUC of 0.66-0.72 for time-to-first-fall and 0.69-0.76 for -second-fall. Daily-life gait quality obtained from a single accelerometer on the trunk is predictive for falls. These findings confirm that ambulant measurements of daily behavior contribute substantially to the identification of elderly at (high risk of falling.

  18. Daily-Life Gait Quality as Predictor of Falls in Older People: A 1-Year Prospective Cohort Study

    Science.gov (United States)

    van Schooten, Kimberley S.; Pijnappels, Mirjam; Rispens, Sietse M.; Elders, Petra J. M.; Lips, Paul; Daffertshofer, Andreas; Beek, Peter J.; van Dieën, Jaap H.

    2016-01-01

    Falls can have devastating consequences for older people. We determined the relationship between the likelihood of fall incidents and daily-life behavior. We used wearable sensors to assess habitual physical activity and daily-life gait quality (in terms of e.g. stability, variability, smoothness and symmetry), and determined their predictive ability for time-to-first-and-second-falls. 319 older people wore a trunk accelerometer (Dynaport MoveMonitor, McRoberts) during one week. Participants further completed questionnaires and performed grip strength and trail making tests to identify risk factors for falls. Their prospective fall incidence was followed up for six to twelve months. We determined interrelations between commonly used gait characteristics to gain insight in their interpretation and determined their association with time-to-falls. For all data -including questionnaires and tests- we determined the corresponding principal components and studied their predictive ability for falls. We showed that gait characteristics of walking speed, stride length, stride frequency, intensity, variability, smoothness, symmetry and complexity were often moderately to highly correlated (r > 0.4). We further showed that these characteristics were predictive of falls. Principal components dominated by history of falls, alcohol consumption, gait quality and muscle strength proved predictive for time-to-fall. The cross-validated prediction models had adequate to high accuracy (time dependent AUC of 0.66–0.72 for time-to-first-fall and 0.69–0.76 for -second-fall). Daily-life gait quality obtained from a single accelerometer on the trunk is predictive for falls. These findings confirm that ambulant measurements of daily behavior contribute substantially to the identification of elderly at (high) risk of falling. PMID:27389583

  19. Consistency of gait characteristics as determined from acceleration data collected at different trunk locations.

    Science.gov (United States)

    Rispens, Sietse M; Pijnappels, Mirjam; van Schooten, Kimberley S; Beek, Peter J; Daffertshofer, Andreas; van Dieën, Jaap H

    2014-01-01

    Estimates of gait characteristics may suffer from errors due to discrepancies in accelerometer location. This is particularly problematic for gait measurements in daily life settings, where consistent sensor positioning is difficult to achieve. To address this problem, we equipped 21 healthy adults with tri-axial accelerometers (DynaPort MiniMod, McRoberts) at the mid and lower lumbar spine and anterior superior iliac spine (L2, L5 and ASIS) while continuously walking outdoors back and forth (20 times) over a distance of 20 m, including turns. We compared 35 gait characteristics between sensor locations by absolute agreement intra-class correlations (2, 1; ICC). We repeated these analyses after applying a new method for off-line sensor realignment providing a unique definition of the vertical and, by symmetry optimization, the two horizontal axes. Agreement between L2 and L5 after realignment was excellent (ICC>0.9) for stride time and frequency, speed and their corresponding variability and good (ICC>0.7) for stride regularity, movement intensity, gait symmetry and smoothness and for local dynamic stability. ICC values benefited from sensor realignment. Agreement between ASIS and the lumbar locations was less strong, in particular for gait characteristics like symmetry, smoothness, and local dynamic stability (ICC generallygait characteristics are robust against limited repositioning error of sensors at the lumbar spine, in particular if our off-line realignment is applied. However, larger positioning differences (from lumbar positions to ASIS) yield less consistent estimates and should hence be avoided. Copyright © 2014 Elsevier B.V. All rights reserved.

  20. How innate is locomotion in precocial animals? A study on the early development of spatio-temporal gait variables and gait symmetry in piglets.

    Science.gov (United States)

    Vanden Hole, Charlotte; Goyens, Jana; Prims, Sara; Fransen, Erik; Ayuso Hernando, Miriam; Van Cruchten, Steven; Aerts, Peter; Van Ginneken, Chris

    2017-08-01

    Locomotion is one of the most important ecological functions in animals. Precocial animals, such as pigs, are capable of independent locomotion shortly after birth. This raises the question whether coordinated movement patterns and the underlying muscular control in these animals is fully innate or whether there still exists a rapid maturation. We addressed this question by studying gait development in neonatal pigs through the analysis of spatio-temporal gait characteristics during locomotion at self-selected speed. To this end, we made video recordings of piglets walking along a corridor at several time points (from 0 h to 96 h). After digitization of the footfalls, we analysed self-selected speed and spatio-temporal characteristics (e.g. stride and step lengths, stride frequency and duty factor) to study dynamic similarity, intralimb coordination and interlimb coordination. To assess the variability of the gait pattern, left-right asymmetry was studied. To distinguish neuromotor maturation from effects caused by growth, both absolute and normalized data (according to the dynamic similarity concept) were included in the analysis. All normalized spatio-temporal variables reached stable values within 4 h of birth, with most of them showing little change after the age of 2 h. Most asymmetry indices showed stable values, hovering around 10%, within 8 h of birth. These results indicate that coordinated movement patterns are not entirely innate, but that a rapid neuromotor maturation, potentially also the result of the rearrangement or recombination of existing motor modules, takes place in these precocial animals. © 2017. Published by The Company of Biologists Ltd.

  1. Mechanical analysis of the acute effects of a heavy resistance exercise warm-up on agility performance in court-sport athletes.

    Science.gov (United States)

    Sole, Christopher J; Moir, Gavin L; Davis, Shala E; Witmer, Chad A

    2013-12-18

    The purpose of this study was to determine the acute effects of heavy resistance exercise on agility performance in court-sport athletes. Five men (age: 20.6 ± 1.9 years; body mass: 79.36 ± 11.74 kg; body height: 1.93 ± 0.09 m) and five women (age 21.2 ± 2.7 years; body mass: 65.8 ± 10.18 kg; body height 1.77 ± 0.08 m) volunteered to participate in the present study. All subjects were NCAA Division II athletes who currently participated in tennis or basketball and all had previous resistance training experience of at least one year. In a counterbalanced design, agility performance during a 10 m shuttle test was assessed following either a dynamic warm-up (DW) or heavy resistance warm-up (HRW) protocol. The HRW protocol consisted of three sets of squats at 50, 60, and 90% of 1-RM. Agility performance was captured using an eight camera motion analysis system and the mechanical variables of stride length, stride frequency, stance time, flight time, average ground reaction force, as well as agility time were recorded. No significant differences were reported for the HRW and DW protocols for any of the mechanical variables (p>0.05), although there was a trend towards the HRW protocol producing faster agility times compared to the control protocol (p = 0.074). Based on the trend towards a significant effect, as well as individual results it is possible that HRW protocols could be used as an acute method to improve agility performance in some court-sport athletes.

  2. Differential responses of fast- and slow-conducting pyramidal tract neurons to changes in accuracy demands during locomotion

    Science.gov (United States)

    Stout, Erik E; Beloozerova, Irina N

    2013-01-01

    Most movements need to be accurate. The neuronal mechanisms controlling accuracy during movements are poorly understood. In this study we compare the activity of fast- and slow-conducting pyramidal tract neurons (PTNs) of the motor cortex in cats as they walk over both a flat surface, a task that does not require accurate stepping and can be accomplished without the motor cortex, as well as along a horizontal ladder, a task that requires accuracy and the activity of the motor cortex to be successful. Fast- and slow-conducting PTNs are known to have distinct biophysical properties as well as different afferent and efferent connections. We found that while the activity of all PTNs changes substantially upon transition from simple locomotion to accurate stepping on the ladder, slow-conducting PTNs respond in a much more concerted manner than fast-conducting ones. As a group, slow-conducting PTNs increase discharge rate, especially during the late stance and early swing phases, decrease discharge variability, have a tendency to shift their preferred phase of the discharge into the swing phase, and almost always produce a single peak of activity per stride during ladder locomotion. In contrast, the fast-conducting PTNs do not display such concerted changes to their activity. In addition, upon transfer from simple locomotion to accurate stepping on the ladder slow-conducting PTNs more profoundly increase the magnitude of their stride-related frequency modulation compared with fast-conducting PTNs. We suggest that slow-conducting PTNs are involved in control of accuracy of locomotor movements to a greater degree than fast-conducting PTNs. PMID:23381901

  3. When does word frequency influence written production?

    Directory of Open Access Journals (Sweden)

    Cristina eBaus

    2013-12-01

    Full Text Available The aim of the present study was to explore the central (e.g., lexical processing and peripheral processes (motor preparation and execution underlying word production during typewriting. To do so, we tested non-professional typers in a picture typing task while continuously recording EEG. Participants were instructed to write (by means of a standard keyboard the corresponding name for a given picture. The lexical frequency of the words was manipulated: half of the picture names were of high-frequency while the remaining were of low-frequency. Different measures were obtained: 1 first keystroke latency and 2 keystroke latency of the subsequent letters and duration of the word. Moreover, ERPs locked to the onset of the picture presentation were analysed to explore the temporal course of word frequency in typewriting. The results showed an effect of word frequency for the first keystroke latency but not for the duration of the word or the speed to which letter were typed (interstroke intervals. The electrophysiological results showed the expected ERP frequency effect at posterior sites: amplitudes for low-frequency words were more positive than those for high-frequency words. However, relative to previous evidence in the spoken modality, the frequency effect appeared in a later time-window. These results demonstrate two marked differences in the processing dynamics underpinning typing compared to speaking: First, central processing dynamics between speaking and typing differ already in the manner that words are accessed; second, central processing differences in typing, unlike speaking, do not cascade to peripheral processes involved in response execution.

  4. When does word frequency influence written production?

    Science.gov (United States)

    Baus, Cristina; Strijkers, Kristof; Costa, Albert

    2013-01-01

    The aim of the present study was to explore the central (e.g., lexical processing) and peripheral processes (motor preparation and execution) underlying word production during typewriting. To do so, we tested non-professional typers in a picture typing task while continuously recording EEG. Participants were instructed to write (by means of a standard keyboard) the corresponding name for a given picture. The lexical frequency of the words was manipulated: half of the picture names were of high-frequency while the remaining were of low-frequency. Different measures were obtained: (1) first keystroke latency and (2) keystroke latency of the subsequent letters and duration of the word. Moreover, ERPs locked to the onset of the picture presentation were analyzed to explore the temporal course of word frequency in typewriting. The results showed an effect of word frequency for the first keystroke latency but not for the duration of the word or the speed to which letter were typed (interstroke intervals). The electrophysiological results showed the expected ERP frequency effect at posterior sites: amplitudes for low-frequency words were more positive than those for high-frequency words. However, relative to previous evidence in the spoken modality, the frequency effect appeared in a later time-window. These results demonstrate two marked differences in the processing dynamics underpinning typing compared to speaking: First, central processing dynamics between speaking and typing differ already in the manner that words are accessed; second, central processing differences in typing, unlike speaking, do not cascade to peripheral processes involved in response execution.

  5. The use of ferrites at microwave frequencies

    CERN Document Server

    Thourel, Léo

    1964-01-01

    The Use of Ferrites at Microwave Frequencies describes the applications of ferrites at microwave frequencies and the apparatus involved. Topics covered range from the properties of ferrites to gyromagnetic and non-reciprocal effects, ferrite isolators, circulators, and modulators. The use of ferrites in variable frequency filter cavities is also discussed. Mathematical explanations are reduced to the strict minimum and only the results of calculations are indicated. This book consists of seven chapters and opens with a review of the theory of magnetism, touching on subjects such as the BOHR m

  6. Frequency characteristics of the laser film digitizer

    International Nuclear Information System (INIS)

    Ishimitsu, Y.; Taira, R.K.; Huang, H.K.

    1988-01-01

    The frequency characteristics of the laser film digitizer in the parallel and in the perpendicular scan direction are different. Because of this difference, moire pattern artifacts may appear in the digitized image. The authors found that this phenomenon is due to the frequency transfer characteristics of the various components in the laser film digitizer. From this observation, they derive a relationship between the spatial frequency content of the original image and the laser beam spot size based on the concept of image contrast. This relationship can be utilized to avoid the appearance of the moire pattern in the digitized image

  7. High power radio frequency attenuation device

    Science.gov (United States)

    Kerns, Quentin A.; Miller, Harold W.

    1984-01-01

    A resistor device for attenuating radio frequency power includes a radio frequency conductor connected to a series of fins formed of high relative magnetic permeability material. The fins are dimensional to accommodate the skin depth of the current conduction therethrough, as well as an inner heat conducting portion where current does not travel. Thermal connections for air or water cooling are provided for the inner heat conducting portions of each fin. Also disclosed is a resistor device to selectively alternate unwanted radio frequency energy in a resonant cavity.

  8. Precision frequency measurements with interferometric weak values

    International Nuclear Information System (INIS)

    Starling, David J.; Dixon, P. Ben; Jordan, Andrew N.; Howell, John C.

    2010-01-01

    We demonstrate an experiment which utilizes a Sagnac interferometer to measure a change in optical frequency of 129 ± 7 kHz/√(Hz) with only 2 mW of continuous-wave, single-mode input power. We describe the measurement of a weak value and show how even higher-frequency sensitivities may be obtained over a bandwidth of several nanometers. This technique has many possible applications, such as precision relative frequency measurements and laser locking without the use of atomic lines.

  9. Variable frequency iteration MPPT for resonant power converters

    Science.gov (United States)

    Zhang, Qian; Bataresh, Issa; Chen, Lin

    2015-06-30

    A method of maximum power point tracking (MPPT) uses an MPPT algorithm to determine a switching frequency for a resonant power converter, including initializing by setting an initial boundary frequency range that is divided into initial frequency sub-ranges bounded by initial frequencies including an initial center frequency and first and second initial bounding frequencies. A first iteration includes measuring initial powers at the initial frequencies to determine a maximum power initial frequency that is used to set a first reduced frequency search range centered or bounded by the maximum power initial frequency including at least a first additional bounding frequency. A second iteration includes calculating first and second center frequencies by averaging adjacent frequent values in the first reduced frequency search range and measuring second power values at the first and second center frequencies. The switching frequency is determined from measured power values including the second power values.

  10. Frequency-Selective Attention in Auditory Scenes Recruits Frequency Representations Throughout Human Superior Temporal Cortex.

    Science.gov (United States)

    Riecke, Lars; Peters, Judith C; Valente, Giancarlo; Kemper, Valentin G; Formisano, Elia; Sorger, Bettina

    2017-05-01

    A sound of interest may be tracked amid other salient sounds by focusing attention on its characteristic features including its frequency. Functional magnetic resonance imaging findings have indicated that frequency representations in human primary auditory cortex (AC) contribute to this feat. However, attentional modulations were examined at relatively low spatial and spectral resolutions, and frequency-selective contributions outside the primary AC could not be established. To address these issues, we compared blood oxygenation level-dependent (BOLD) responses in the superior temporal cortex of human listeners while they identified single frequencies versus listened selectively for various frequencies within a multifrequency scene. Using best-frequency mapping, we observed that the detailed spatial layout of attention-induced BOLD response enhancements in primary AC follows the tonotopy of stimulus-driven frequency representations-analogous to the "spotlight" of attention enhancing visuospatial representations in retinotopic visual cortex. Moreover, using an algorithm trained to discriminate stimulus-driven frequency representations, we could successfully decode the focus of frequency-selective attention from listeners' BOLD response patterns in nonprimary AC. Our results indicate that the human brain facilitates selective listening to a frequency of interest in a scene by reinforcing the fine-grained activity pattern throughout the entire superior temporal cortex that would be evoked if that frequency was present alone. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  11. Dynamic resonant frequency control of ultrasonic transducer for stabilizing resonant state in wide frequency band

    Science.gov (United States)

    Yokozawa, Hiroki; Twiefel, Jens; Weinstein, Michael; Morita, Takeshi

    2017-07-01

    Controlling the resonant frequency of ultrasonic transducers is important to achieve the excellent performance of ultrasonic devices. The resonant frequency can be shifted by a nonlinear effect or by increasing the temperature under high-power operation. We propose a resonant frequency control method during the transducer’s operation that enables the dynamic compensation of resonant frequency shifts. To realize this, a transducer with passive piezoelectric parts was fabricated. By controlling the electric boundary condition of the passive piezoelectric parts between short and open by utilizing a metal-oxide-semiconductor field-effect transistor (MOSFET), the stiffness was changed, thus modifying the resonant frequency. In both simulation and experiment, the resonant frequency was modified successfully by controlling the switching duty ratio of the MOSFET. Additionally, a system for exciting a transducer at a resonant state with a wide frequency band was demonstrated.

  12. Detecting deception via eyeblink frequency modulation

    Directory of Open Access Journals (Sweden)

    Brandon S. Perelman

    2014-02-01

    Full Text Available To assess the efficacy of using eyeblink frequency modulation to detect deception about a third party, 32 participants were sent on a mission to deliver a package to an interviewer. 17 of the participants lied to the interviewer about the details of their mock mission and 15 responded truthfully. During the interview, eyeblink frequency data were collected via electromyography and recorded video. Liars displayed eyeblink frequency suppression while lying, while truth tellers exhibited an increase in eyeblink frequency during the mission relevant questioning period. The compensatory flurry of eyeblinks following deception observed in previous studies was absent in the present study. A discriminant function using eyeblink suppression to predict lying correctly classified 81.3% of cases, with a sensitivity of 88.2% and a specificity of 73.3%. This technique, yielding a reasonable sensitivity, shows promise for future testing as, unlike polygraph, it is compatible with distance technology.

  13. Configural face encoding and spatial frequency information.

    Science.gov (United States)

    Boutet, Isabelle; Collin, Charles; Faubert, Jocelyn

    2003-10-01

    Configural relations and a critical band of spatial frequencies (SFs) in the middle range are particularly important for face recognition. We report the results of four experiments in which the relationship between these two types of information was examined. In Experiments 1, 2A, and 2B, the face inversion effect (FIE) was used to probe configural face encoding. Recognition of upright and inverted faces and nonface objects was measured in four conditions: a no-filter condition and three SF conditions (low, medium, and high frequency). We found significant FIEs of comparable magnitudes for all frequency conditions. In Experiment 3, discrimination of faces on the basis of either configural or featural modifications was measured under the same four conditions. Although the ability to discriminate configural modifications was superior in the medium-frequency condition, so was the ability to discriminate featural modifications. We conclude that the band of SF that is critical for face recognition does not contribute preferentially to configural encoding.

  14. Damping Estimation by Frequency Domain Decomposition

    DEFF Research Database (Denmark)

    Brincker, Rune; Ventura, C. E.; Andersen, P.

    2001-01-01

    In this paper it is explained how the damping can be estimated using the Frequency Domain Decomposition technique for output-only modal identification, i.e. in the case where the modal parameters is to be estimated without knowing the forces exciting the system. Also it is explained how the natural...... back to time domain to identify damping and frequency. The technique is illustrated on a simple simulation case with 2 closely spaced modes. On this example it is illustrated how the identification is influenced by very closely spacing, by non-orthogonal modes, and by correlated input. The technique...... frequencies can be accurately estimated without being limited by the frequency resolution of the discrete Fourier transform. It is explained how the spectral density matrix is decomposed into a set of single degree of freedom systems, and how the individual SDOF auto spectral density functions are transformed...

  15. High frequency conductivity in carbon nanotubes

    Directory of Open Access Journals (Sweden)

    S. S. Abukari

    2012-12-01

    Full Text Available We report on theoretical analysis of high frequency conductivity in carbon nanotubes. Using the kinetic equation with constant relaxation time, an analytical expression for the complex conductivity is obtained. The real part of the complex conductivity is initially negative at zero frequency and become more negative with increasing frequency, until it reaches a resonance minimum at ω ∼ ωB for metallic zigzag CNs and ω < ωB for armchair CNs. This resonance enhancement is indicative for terahertz gain without the formation of current instabilities induced by negative dc conductivity. We noted that due to the high density of states of conduction electrons in metallic zigzag carbon nanotubes and the specific dispersion law inherent in hexagonal crystalline structure result in a uniquely high frequency conductivity than the corresponding values for metallic armchair carbon nanotubes. We suggest that this phenomenon can be used to suppress current instabilities that are normally associated with a negative dc differential conductivity.

  16. Frequency Steered Acoustic Transducer, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — This Small Business Innovation Research Phase II project is to fabricate, characterize, and verify performance of a new type of frequency steered acoustic transducer...

  17. Global Volcano Hazard Frequency and Distribution

    Data.gov (United States)

    National Aeronautics and Space Administration — Global Volcano Hazard Frequency and Distribution is a 2.5 minute gridded data set based upon the National Geophysical Data Center (NGDC) Volcano Database spanning...

  18. SRS Process Facility Significance Fire Frequency

    International Nuclear Information System (INIS)

    Sarrack, A.G.

    1995-10-01

    This report documents the method and assumptions of a study performed to determine a site generic process facility significant fire initiator frequency and explains the proper way this value should be used

  19. Frequency spectrum of Calder Hall reactor noise

    International Nuclear Information System (INIS)

    Cummins, J.D.

    1960-01-01

    The frequency spectrum of the noise power of Calder Hall reactor No. 1 has been obtained by analysing a tape recording of the backed off power. The root mean square noise power due to all frequencies above 0.001 cycles per second was found to be 0.13%. The noise power for this reactor, is due mainly to modulations of the power level by reactivity variations caused in turn by gas temperature changes. These gas temperature changes are caused by a Cyclic variation in the feedwater regulator to the heat exchanger. The apparatus and method used to determine the noise power are described in this memorandum. It is shown that for frequencies in the range 0.001 to 0.030 cycles per second the noise spectrum falls at 60 decibels per decade of frequency. (author)

  20. Global Earthquake Hazard Frequency and Distribution

    Data.gov (United States)

    National Aeronautics and Space Administration — Global Earthquake Hazard Frequency and Distribution is a 2.5 by 2.5 minute global utilizing Advanced National Seismic System (ANSS) Earthquake Catalog data of actual...

  1. Damped Oscillator with Delta-Kicked Frequency

    Science.gov (United States)

    Manko, O. V.

    1996-01-01

    Exact solutions of the Schrodinger equation for quantum damped oscillator subject to frequency delta-kick describing squeezed states are obtained. The cases of strong, intermediate, and weak damping are investigated.

  2. Global Drought Hazard Frequency and Distribution

    Data.gov (United States)

    National Aeronautics and Space Administration — Global Drought Hazard Frequency and Distribution is a 2.5 minute grid based upon the International Research Institute for Climate Prediction's (IRI) Weighted Anomaly...

  3. 47 CFR 78.111 - Frequency tolerance.

    Science.gov (United States)

    2010-10-01

    ... carrier frequency of each authorized transmitter to within the following percentage of the assigned... to 18,920 0.001 18,920 to 19,700 0.003 1 Stations that employing vestigal sideband AM transmissions...

  4. Fast and Statistically Efficient Fundamental Frequency Estimation

    DEFF Research Database (Denmark)

    Nielsen, Jesper Kjær; Jensen, Tobias Lindstrøm; Jensen, Jesper Rindom

    2016-01-01

    Fundamental frequency estimation is a very important task in many applications involving periodic signals. For computational reasons, fast autocorrelation-based estimation methods are often used despite parametric estimation methods having superior estimation accuracy. However, these parametric...

  5. Global Earthquake Hazard Frequency and Distribution

    Data.gov (United States)

    National Aeronautics and Space Administration — Global Earthquake Hazard Frequency and Distribution is a 2.5 minute grid utilizing Advanced National Seismic System (ANSS) Earthquake Catalog data of actual...

  6. Digital repetitive control under varying frequency conditions

    CERN Document Server

    Ramos, Germán A; Olm, Josep M

    2013-01-01

    The tracking/rejection of periodic signals constitutes a wide field of research in the control theory and applications area. Repetitive Control has proven to be an efficient way to face this topic. However, in some applications the frequency of the reference/disturbance signal is time-varying or uncertain. This causes an important performance degradation in the standard Repetitive Control scheme. This book presents some solutions to apply Repetitive Control in varying frequency conditions without loosing steady-state performance. It also includes a complete theoretical development and experimental results in two representative systems. The presented solutions are organized in two complementary branches: varying sampling period Repetitive Control and High Order Repetitive Control. The first approach allows dealing with large range frequency variations while the second allows dealing with small range frequency variations. The book also presents applications of the described techniques to a Roto-magnet plant and...

  7. Global Flood Hazard Frequency and Distribution

    Data.gov (United States)

    National Aeronautics and Space Administration — Global Flood Hazard Frequency and Distribution is a 2.5 minute grid derived from a global listing of extreme flood events between 1985 and 2003 (poor or missing data...

  8. SRS Process Facility Significance Fire Frequency

    Energy Technology Data Exchange (ETDEWEB)

    Sarrack, A.G. [Westinghouse Savannah River Company, AIKEN, SC (United States)

    1995-10-01

    This report documents the method and assumptions of a study performed to determine a site generic process facility significant fire initiator frequency and explains the proper way this value should be used.

  9. MDS 3.0 Frequency Report

    Data.gov (United States)

    U.S. Department of Health & Human Services — The MDS 3.0 Frequency Report summarizes information for active residents currently in nursing homes. The source of these counts is the residents MDS assessment...

  10. Global Cyclone Hazard Frequency and Distribution

    Data.gov (United States)

    National Aeronautics and Space Administration — Global Cyclone Hazard Frequency and Distribution is a 2.5 minute grid based on more than 1,600 storm tracks for the period 1 January 1980 through 31 December 2000...

  11. Voltage, Temperature, Frequency Margin Test Report

    DEFF Research Database (Denmark)

    Denver, Troelz

    1999-01-01

    The purpose of the tests is to establish the camera functionality when it is exposed to an extreme environment for prolonged periods, thus simulating the end of life performance. This environment covers temperature, input clock frequency and supply voltage variation...

  12. Frequency Steered Acoustic Transducer, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — This Small Business Innovation Research Phase I project is to develop, fabricate, and characterize a novel frequency steered acoustic transducer (FSAT) for the...

  13. Slot Machine Response Frequency Predicts Pathological Gambling

    DEFF Research Database (Denmark)

    Linnet, Jakob; Rømer Thomsen, Kristine; Møller, Arne

    2013-01-01

    Slot machines are among the most addictive forms of gambling, and pathological gambling slot machine players represent the largest group of treatment seekers, accounting for 35% to 93% of the population. Pathological gambling sufferers have significantly higher response frequency (games / time......) on slot machines compared with non-problem gamblers, which may suggest increased reinforcement of the gambling behavior in pathological gambling. However, to date it is unknown whether or not the increased response frequency in pathological gambling is associated with symptom severity of the disorder....... This study tested the hypothesis that response frequency is associated with symptom severity in pathological gambling. We tested response frequency among twenty-two pathological gambling sufferers and twenty-one non-problem gamblers on a commercially available slot machine, and screened for pathological...

  14. Design of multi-frequency CW radars

    CERN Document Server

    Jankiraman, Mohinder

    2007-01-01

    This book deals with the basic theory for design and analysis of Low Probability of Intercept (LPI) radar systems. The design of one such multi-frequency high resolution LPI radar, PANDORA, is covered.

  15. Passive Shielding for Low Frequency Magnetic Films

    National Research Council Canada - National Science Library

    Damaskos, Nickander

    1997-01-01

    Report developed under SBIR Contract. An approach to low frequency shielding is shown with application to suppression of electromagnetic fields emanating from rail gun barrels and power cable busses. Damaskos, Inc...

  16. Progress on new vaccine strategies for the immunotherapy and prevention of cancer

    OpenAIRE

    Berzofsky, Jay A.; Terabe, Masaki; Oh, SangKon; Belyakov, Igor M.; Ahlers, Jeffrey D.; Janik, John E.; Morris, John C.

    2004-01-01

    In recent years, great strides in understanding and regulating the immune system have led to new hope for harnessing its exquisite specificity to destroy cancer cells without affecting normal tissues. This review examines the fundamental immunologic advances and the novel vaccine strategies arising from these advances, as well as the early clinical trials studying new approaches to treat or prevent cancer.

  17. Observations on the State of Indigenous Human Rights in Light of the UN Declaration on the Rights of Indigenous Peoples: Guatemala

    Science.gov (United States)

    Cultural Survival, 2008

    2008-01-01

    Since the 1996 Peace Accords ended the Guatemalan civil war, the country has made strides to legally recognize the rights of its indigenous peoples and has criminalized racial discrimination. However, political exclusion, discrimination, and economic marginalization of indigenous peoples still regularly occur due to the lack of resources and…

  18. Antenatal screening for hepatitis B virus in HIV-infected and ...

    African Journals Online (AJOL)

    Despite enormous strides in preventing hepatitis B virus (HBV) infection, perinatal transmission still contributes significantly ... The hepatitis B surface antigen (HBsAg) prevalence was significantly higher (2.1%) among ..... Burnett RJ, Kramvis A, Dochez C, Meheus A. An update after 16 years of hepatitis B vaccination in.

  19. Kinetic comparison of walking on a treadmill versus over ground in children with cerebral palsy

    NARCIS (Netherlands)

    van der Krogt, M.M.; Sloot, L.H.; Buizer, A.I.; Harlaar, J.

    2015-01-01

    Kinetic outcomes are an essential part of clinical gait analysis, and can be collected for many consecutive strides using instrumented treadmills. However, the validity of treadmill kinetic outcomes has not been demonstrated for children with cerebral palsy (CP). In this study we compared ground

  20. Research Review

    Science.gov (United States)

    Serig, Dan; Hinojosa, Tina

    2010-01-01

    The field of community art within higher education has made tremendous strides in the past two decades. The origins of community visual arts programming are ambiguous and traceable to multiple time periods and cultural contexts. However, in contemporary practices, higher education institutions are slowly adopting a greater priority for community…

  1. Kinetics of pressure induced structural phase transitions—A review

    Indian Academy of Sciences (India)

    Unknown

    The experimental technique using the diamond anvil cell (DAC) and image processing gets spe- cial mention as it promises to impart a new .... cal picture of the microscopic changes accompanying a transition. In fact, the major strides made ... 1983, 1986; Vohra et al 1986; Mao et al 1990; Yousuf. 1998). Also, in shock wave ...

  2. Other | Information | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Striding steadily on the path of being India's first smart city, Bhopal houses various institutions and installations of scientific importance. This includes ISRO's Master Control Facility and BHEL. Bhopal is also home to the largest number of institutions of higher scientific education namely, IISER, MANIT, SPA, AIIMS and NLIU.

  3. CLAVES CIENTÍFICAS PARA UNA ENSEÑANZA DE CALIDAD

    Directory of Open Access Journals (Sweden)

    Ignacio Morgado Bernal

    2012-05-01

    We have recently made great strides on how the human brain represents and stores information. Learning basically means acquiring new neuronal representations of knowledge and establishing functional connections between them and the ones previously existent in our brain. This is possible because when we learn we make new connections (synapses between neurons storing knowledge or we reinforce those previously existing.

  4. Steel Band Repertoire: The Case for Original Music

    Science.gov (United States)

    Tanner, Chris

    2010-01-01

    In the past few decades, the steel band art form has experienced consistent growth and development in several key respects. For example, in the United States, the sheer number of steel band programs has steadily increased, and it appears that this trend will continue in the future. Additionally, pan builders and tuners have made great strides in…

  5. Integrating Digital Technologies in Teaching Learning Process

    Science.gov (United States)

    Nagarajan, R.; Velmanirajan, K.; Kanna, K. Sankesh

    2013-01-01

    India has made impressive strides in the application of information and communication technology in recent years and this has reflected in a vibrant and fast growing economy. It is now an acknowledged world leader in the knowledge industry. In this paper an attempt is made to highlight the role of Information and Communication Technology (ICT) in…

  6. African communalism and globalization | Etta | African Research ...

    African Journals Online (AJOL)

    In this connection, it is the belief of this work that the current wind of globalization that the world is embracing is of no much difference from African communalism. As such, this work suggests that each of the above should complement the other in harnessing developmental strides while pursuing the empowerment of the ...

  7. Quality of Health Care in Ghana: Mapping of Interventions and the ...

    African Journals Online (AJOL)

    Background. Ghana has made major strides in improving access to health services. Despite these improvements, Ghana did not meet the Millennium Development Goals 4 and 5. Quality of care is a major factor that could explain this shortfall. Objective. To understand current practice and to identify needs in the area of ...

  8. AFRREV LALIGENS

    African Journals Online (AJOL)

    Toshiba

    2014-02-07

    Feb 7, 2014 ... College of Humanities and Culture. Ikire Campus. +2348033810610. E-mail: Temitayo .... country‟s educational sector and quest for national development? What has been the stride so far, where do the ..... The primary level of education is the most important level of education. This is because the quality of ...

  9. Equal Justice and the Digital Revolution: Using Technology To Meet the Legal Needs of Low-Income People.

    Science.gov (United States)

    Gordon, Julia

    This report describes one group of nonprofit organizations that provide free civil legal assistance to qualifying low-income people. Between 1997-2001, legal services programs made significant strides in using technology to improve services. In the mid-1990s, they began using new technologies on an increasingly regular basis. However, few had…

  10. How Students Rate the Quality Service Climate on Campus. National Research Report, 2011

    Science.gov (United States)

    Noel-Levitz, Inc, 2011

    2011-01-01

    How satisfied are students with the service they receive--and how important is it to them? This report documents significant strides that colleges and universities have made in recent years to improve service quality and their overall campus climate, yet also finds that campuses still have room for improvement. A few highlights: (1) While progress…

  11. How Students Rate the Quality Service Climate on Campus. National Research Report, 2012

    Science.gov (United States)

    Noel-Levitz, Inc, 2012

    2012-01-01

    How satisfied are students with the service they receive--and how important is it to them? This report documents significant strides that colleges and universities have made in recent years to improve service quality and their overall campus climate, yet also finds that campuses still have room for improvement. A few highlights: (1) While progress…

  12. Public and Private Universities in Taiwan: To Compete or Not to Compete? RIHE International Seminar Reports. No. 23

    Science.gov (United States)

    Chen, Robin J.

    2015-01-01

    Since the 1950s, Taiwan has made great strides in higher education. However, its developmental growth has not been stable. Different studies show different ways to distinguish the stages of higher education development: Chen (2008) stated the stages of development in Taiwan from 1949 to the present can be seen as the following eras: early…

  13. State of the art. Neonatal respiratory failure.

    Science.gov (United States)

    Parker, L A

    1999-12-01

    Advances in ventilatory management of respiratory distress in the newborn have made dramatic strides during the last decade. Innovative treatments such as PTV, HFV, liquid ventilation, and NO therapy are just beginning to have an impact on the care of neonates in the NICU. These treatment modalities should continue to have an effect on the care of the newborn infant well into the future.

  14. an improved map based graphical android authentication system

    African Journals Online (AJOL)

    Ahmad et al.

    device systems, and thus there is need for security innovations and improvements. Security practitioners and researchers have made strides in protecting systems and mobile device. However, the problem arises that, until recently, security was treated wholly as a technical problem – the system user was not factored into.

  15. Simultaneous Analysis of Bioactive Markers from Orthosiphon ...

    African Journals Online (AJOL)

    Erah

    variety of kidney and bladder pathologies, especially kidney stones, pain in the bladder with frequent urination, as well as accumulation of uric acid crystals in joints owing to elevated blood uric acid levels [3-5]. Technological strides in chromatographic and spectroscopic methods have brought tremen- dous influence on the ...

  16. Averaged EMG profiles in jogging and running at different speeds

    NARCIS (Netherlands)

    Gazendam, Marnix G. J.; Hof, At L.

    EMGs were collected from 14 muscles with surface electrodes in 10 subjects walking 1.25-2.25 m s(-1) and running 1.25-4.5 m s(-1). The EMGs were rectified, interpolated in 100% of the stride, and averaged over all subjects to give an average profile. In running, these profiles could be decomposed

  17. Smart Technology Applications in Business Environments

    NARCIS (Netherlands)

    Issa, Tomayess; Kommers, Petrus A.M.; Issa, Theodora; Isaías, Pedro; Issa, Touma B.

    2017-01-01

    Technology continues to make great strides in society by providing opportunities for advancement, inclusion, and global competency. As new systems and tools arise, novel applications are created as well. Smart Technology Applications in Business Environments is an essential reference source for the

  18. MDGS

    African Journals Online (AJOL)

    User

    such,some countries have since made giant strides in this race to meet the MDGs before the target date. In sub-Saharan Africa, Rwanda –a country recovering from the genocide of the early 1990s –is a model of such positive development planning fashioned towards the MDGs. Poverty rates in Rwanda were increasing in ...

  19. Procurement under the Uncitral model law: a southern Africa ...

    African Journals Online (AJOL)

    The stages for opening up procurement markets, referred to by Yukins and Schooner, is discussed and it is concluded that the states in SADC is still in the initial stages of opening its public procurement markets for regional competition. Although COMESA is not yet in full compliance with all four the stages great strides have ...

  20. Communication Experiences of Latina and Latino Immigrant Custodial Workers within a University Setting

    Science.gov (United States)

    Alvarez, Wilfredo

    2011-01-01

    The organizational communication subdiscipline has made great strides in theory and research in recent years, but little is known about the workplace communication experiences of Latinas and Latinos in the United States. Even less is known about these sociocultural group members' experiences when they work in lower status, blue-collar roles in…

  1. An on-ice measurement approach to analyse the biomechanics of ice hockey skating.

    Directory of Open Access Journals (Sweden)

    Erica Buckeridge

    Full Text Available Skating is a fundamental movement in ice hockey; however little research has been conducted within the field of hockey skating biomechanics due to the difficulties of on-ice data collection. In this study a novel on-ice measurement approach was tested for reliability, and subsequently implemented to investigate the forward skating technique, as well as technique differences across skill levels. Nine high caliber (High and nine low caliber (Low hockey players performed 30 m forward skating trials. A 3D accelerometer was mounted to the right skate for the purpose of stride detection, with the 2nd and 6th strides defined as acceleration and steady-state, respectively. The activity of five lower extremity muscles was recorded using surface electromyography. Biaxial electro-goniometers were used to quantify hip and knee angles, and in-skate plantar force was measured using instrumented insoles. Reliability was assessed with the coefficient of multiple correlation, which demonstrated moderate (r>0.65 to excellent (r>0.95 scores across selected measured variables. Greater plantar-flexor muscle activity and hip extension were evident during acceleration strides, while steady state strides exhibited greater knee extensor activity and hip abduction range of motion (p<0.05. High caliber exhibited greater hip range of motion and forefoot force application (p<0.05. The successful implementation of this on-ice mobile measurement approach offers potential for athlete monitoring, biofeedback and training advice.

  2. A Review of Terminological, Conceptual, and Methodological Issues in the Developmental Risk Factor Literature for Antisocial and Delinquent Behavior

    Science.gov (United States)

    Day, David M.; Wanklyn, Sonya G.; Yessine, Annie K.

    2014-01-01

    Background: The study of risk factors for antisocial and delinquent behavior has flourished in the past 20 years, as great strides have been made in understanding the developmental pathways that give rise to the onset, course, and desistance of the behavior. However, as a body of literature, risk factor research (RFR) is characterized by…

  3. Measuring Environmental Health Perception among College Students

    Science.gov (United States)

    Ratnapradipa, Dhitinut; Brown, Stephen L.; Middleton, Wendi K.; Wodika, Alicia B.

    2011-01-01

    One's knowledge, perception, and attitude are fundamental in determining how one behaves regarding environmental hazards. While science has made great strides in promoting environmental health, threats still exist, largely due to individual actions in response to potential health hazards. Undergraduate students (n = 395) enrolled in an…

  4. Relationships of Balance, Gait Performance, and Functional Outcome in Chronic Stroke Patients: A Comparison of Left and Right Lesions.

    Science.gov (United States)

    Lopes, Priscila Garcia; Lopes, José Augusto Fernandes; Brito, Christina Moran; Alfieri, Fábio Marcon; Rizzo Battistella, Linamara

    2015-01-01

    This study compared the balance by center of pressure (COP) and its relationship with gait parameters and functional independence in left (LH) and right (RH) chronic stroke patients. In this cross-sectional study, twenty-one hemiparetic stroke patients were assessed for Functional Independence Measure (FIM), balance with a force platform, and gait in the Motion Analysis Laboratory. The amplitudes of the COP in the anteroposterior and mediolateral directions were similar in both groups. The anteroposterior direction was greater than the mediolateral direction. Only the temporal parameters showed any statistically significant differences. The LH showed a significant correlation between stride length, step length, and gait velocity with COP velocity sway for the healthy and paretic lower limbs. In both groups, the area of COP was significantly correlated with stride length. Motor FIM was significantly correlated with the COP in the LH group. There was no difference in the performance of balance, gait, and functional independence between groups. The correlation of the COP sway area with stride length in both groups can serve as a guideline in the rehabilitation of these patients where training the static balance may reflect the improvement of the stride length.

  5. Relationships of Balance, Gait Performance, and Functional Outcome in Chronic Stroke Patients: A Comparison of Left and Right Lesions

    Directory of Open Access Journals (Sweden)

    Priscila Garcia Lopes

    2015-01-01

    Full Text Available Introduction. This study compared the balance by center of pressure (COP and its relationship with gait parameters and functional independence in left (LH and right (RH chronic stroke patients. Methods. In this cross-sectional study, twenty-one hemiparetic stroke patients were assessed for Functional Independence Measure (FIM, balance with a force platform, and gait in the Motion Analysis Laboratory. Results. The amplitudes of the COP in the anteroposterior and mediolateral directions were similar in both groups. The anteroposterior direction was greater than the mediolateral direction. Only the temporal parameters showed any statistically significant differences. The LH showed a significant correlation between stride length, step length, and gait velocity with COP velocity sway for the healthy and paretic lower limbs. In both groups, the area of COP was significantly correlated with stride length. Motor FIM was significantly correlated with the COP in the LH group. Conclusion. There was no difference in the performance of balance, gait, and functional independence between groups. The correlation of the COP sway area with stride length in both groups can serve as a guideline in the rehabilitation of these patients where training the static balance may reflect the improvement of the stride length.

  6. Depressive symptoms and gait dysfunction in the elderly.

    Science.gov (United States)

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

    2012-05-01

    Assess the association between depressive symptoms (not meeting the criteria for major depression) and gait dysfunction in older adults. Cross-sectional study. Einstein Aging Study, a community-based longitudinal aging study. Six hundred ten nondemented and nondepressed community-residing adults age 70 and older. Depressive symptoms measured using the 15-item Geriatric Depression Scale. To obtain a comprehensive assessment of gait, eight individual quantitative gait parameters were assessed: velocity (cm/s), stride length (cm), cadence (steps/min), swing phase (seconds), stance phase (seconds), double support phase (seconds), stride length variability (SD of stride length), and swing time variability (SD of swing time). Multiple linear regression analysis was applied to study the association of depressive symptoms with gait, adjusting for potential confounders including demographic variables, medical illnesses, and clinical gait abnormalities. Increased level of depressive symptoms was associated with worse velocity, stride, and swing time variability. The relationship of the remaining five gait variables with depressive symptoms was not significant in the fully adjusted models. Higher levels of depressive symptoms are associated with worse performance in specific quantitative gait variables in community-residing older adults.

  7. Normative EMG activation patterns of school-age children during gait.

    Science.gov (United States)

    Agostini, V; Nascimbeni, A; Gaffuri, A; Imazio, P; Benedetti, M G; Knaflitz, M

    2010-07-01

    Gait analysis is widely used in clinics to study walking abnormalities for surgery planning, definition of rehabilitation protocols, and objective evaluation of clinical outcomes. Surface electromyography allows the study of muscle activity non-invasively and the evaluation of the timing of muscle activation during movement. The aim of this study was to present a normative dataset of muscle activation patterns obtained from a large number of strides in a population of 100 healthy children aged 6-11 years. The activity of Tibialis Anterior, Lateral head of Gastrocnemius, Vastus Medialis, Rectus Femoris and Lateral Hamstrings on both lower limbs was analyzed during a 2.5-min walk at free speed. More than 120 consecutive strides were analyzed for each child, resulting in approximately 28,000 strides. Onset and offset instants were reported for each observed muscle. The analysis of a high number of strides for each participant allowed us to obtain the most recurrent patterns of activation during gait, demonstrating that a subject uses a specific muscle with different activation modalities even in the same walk. The knowledge of the various activation patterns and of their statistics will be of help in clinical gait analysis and will serve as reference in the design of future gait studies. Copyright © 2010 Elsevier B.V. All rights reserved.

  8. Antenatal screening for hepatitis B virus in HIV-infected and ...

    African Journals Online (AJOL)

    Background. Despite enormous strides in preventing hepatitis B virus (HBV) infection, perinatal transmission still contributes significantly to HBV epidemiology worldwide; this could account for approximately 50% of chronically infected individuals. Objective. To assess the need for HBV screening in antenatal clinics in the ...

  9. Improving the Weight of the Nation by engaging the medical setting in obesity prevention and control.

    Science.gov (United States)

    Foltz, Jennifer L; Belay, Brook; Blackburn, George L

    2013-01-01

    This manuscript highlights examples of strategies that have made strides in improving the quality of health care environments, systems-level improvements to support self-management, and collaborations between primary care and public health to support effective approaches to prevent obesity among children and adults in the U.S. © 2013 American Society of Law, Medicine & Ethics, Inc.

  10. Women's Education and Earnings in Texas.

    Science.gov (United States)

    Werschkul, Misha; Gault, Barbara; Caiazza, Amy; Hartmann, Heidi

    2005-01-01

    Women have made remarkable strides in education during the past three decades, but these gains have yet to translate into full equity in pay. Women still earn less than men earn in nearly every profession and at every stage of their careers, and this earnings gap is evident in every state in the nation. This report focuses on educational…

  11. Advancing Evidence Based Policymaking and Regulation to Ensure ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Advancing Evidence Based Policymaking and Regulation to Ensure Greater Participation in ICTs (LIRNEasia Phase II). Significant strides have been made in closing the digital divide in Asia, mainly due to the proliferation of mobile telephones. Close to a billion people, some among the poorest segments of society, have ...

  12. Search Results | Page 13 | IDRC - International Development ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Results 121 - 130 of 420 ... Significant strides have been made in closing the digital divide in Asia, mainly due to the proliferation of mobile telephones. Close to a billion people, some among the poorest segments of society, have joined the mobile information society. Project.

  13. What we do | Page 128 | IDRC - International Development ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Advancing Evidence Based Policymaking and Regulation to Ensure Greater Participation in ICTs (LIRNEasia Phase II). Significant strides have been made in closing the digital divide in Asia, mainly due to the proliferation of mobile telephones. Central Asia, Far East Asia, South Asia. PROJECT ...

  14. Truly Green: A Look at the Advantages of Maintaining Historic Campus Buildings

    Science.gov (United States)

    Brown, Julie Paul; Hillman, Luce R.

    2010-01-01

    Most colleges and universities have taken great strides in recent years to embrace "being green." As part of this process, many institutions have established an Office of Sustainability or similar department to implement these practices and foster the image of environmental consciousness that the universities want to project. Institutions are…

  15. S K Pati, JNCASR, Bangalore

    Indian Academy of Sciences (India)

    admin

    The new millennium has seen rapid strides being made in the fields of nanotechnology and molecular electronics. With miniaturization reaching hitherto unknown limits, DNA presents itself as an ideal molecule that possesses superior properties of self-assembly, optimized through billions of years of evolution. Our research ...

  16. The Asele Period in Uche Okeke's Creativity 1958-1966 ...

    African Journals Online (AJOL)

    The Asele Period is a research study of a major aspect of the creative works of Professor Uche Okeke. The artist, who is generally regarded as father of modern Nigerian art tradition, has made various giant strides in the creative development of the country. He is naturally endowed with skill and good knowledge of the ...

  17. Kofi Annan: A Man of Peace in a World of War

    African Journals Online (AJOL)

    Treaty Organisation (NATO). In the end, NATO – and not the UN – intervened and patrolled Kosovo with peacekeeping troops. Spurred by reports and controversies over UN ... stride: the so-called oil for food scandal. In 2004 his son, Kojo, was mired in the scandal and all of these pressures left him tired, depressed.

  18. Women Community College Presidents: A Qualitative Approach to Exploring Leadership and Overcoming Potential Barriers

    Science.gov (United States)

    O'Roark, Jordan J.

    2015-01-01

    Since the establishment of American higher education, the presidential profile for institutions has lacked the gender diversity in presidential leadership positions. Though women have taken positive strides as senior executive officers in higher education in the past quarter-century, the conventional post-secondary president is a white, married…

  19. Undermining Racism and a Whiteness Ideology: White Principals Living a Commitment to Equitable and Excellent Schools

    Science.gov (United States)

    Theoharis, George; Haddix, Marcelle

    2011-01-01

    This article reports on six White urban principals who came to administration with a commitment to create more equitable and excellent schools for students from marginalized communities. These leaders made strides in raising student achievement, creating a climate of belonging for students, staff, and families, and increasing access to learning…

  20. Environmentally conscious design of upstream crude oil supply chain

    NARCIS (Netherlands)

    Sahebi, H.; Nickel, S.; Ashayeri, J.

    In the past few decades, very rapid growth in environmental legislation has resulted in an increasing will of companies to address environmental thinking through their supply chain. In this context, great strides have been made to incorporate the environmental concerns, such as “green” and

  1. BIOSENSOR TECHNOLOGY EVALUATIONS FOR REAL-TIME/SOURCE WATER PROTECTION

    Science.gov (United States)

    Recent advances in electronics and computer technology have made great strides in the field of remote sensing and biomonitoring. The quality of drinking water sources has come under closer scrutiny in recent years. Issues ranging from ecological to public health and national se...

  2. A Longitudinal Study of Implementing Reality Pedagogy in an Urban Science Classroom: Effects, Challenges, and Recommendations for Science Teaching and Learning

    Science.gov (United States)

    Borges, Sheila Ivelisse

    2016-01-01

    Statistics indicate that students who reside in "forgotten places" do not engage in science-related careers. This is problematic because we are not tapping into diverse talent that could very well make scientific strides and because there is a moral obligation for equity as discussed in "Science for all" (AAAS, 1989). Research…

  3. Future Directions for EHDI Programs: Recommendations from a Strategic Analysis

    Science.gov (United States)

    Bradham, Tamala S.; Houston, K. Todd

    2011-01-01

    Over the past 20 years, tremendous strides have been made in establishing and strengthening early hearing detection and intervention (EHDI) programs in all 50 states and the U.S. territories. Although EHDI programs have become more robust, considerable work remains to ensure that all children who do not pass a hearing screening receive the…

  4. Understanding Statistics and Statistics Education: A Chinese Perspective

    Science.gov (United States)

    Shi, Ning-Zhong; He, Xuming; Tao, Jian

    2009-01-01

    In recent years, statistics education in China has made great strides. However, there still exists a fairly large gap with the advanced levels of statistics education in more developed countries. In this paper, we identify some existing problems in statistics education in Chinese schools and make some proposals as to how they may be overcome. We…

  5. A high speed OCT system developed at the CSIR National Laser Centre

    CSIR Research Space (South Africa)

    Sharma, Ameeth

    2016-07-01

    Full Text Available reported by Huang in 1991[1], OCT has made significant strides in different fields from dermatology and ophthalmology to polymer characterisation and bio-metrics[2-4]. In South Africa, the technique is still emerging although it is being used for eye...

  6. An Analysis of China's Fertilizer Policies: Impacts on the Industry, Food Security, and the Environment

    NARCIS (Netherlands)

    Li, Y.X.; Zhang, W.F.; Ma, L.; Huang, G.Q.; Oenema, O.; Zhang, F.S.; Dou, Z.X.

    2013-01-01

    China has made remarkable strides in recent decades to grow enough food to feed 20% of the world's population with only 9% of the world's arable land. Meanwhile, the nation is experiencing exacerbated air and water pollution problems. Agricultural growth and the pollution aggravation are closely

  7. Download this PDF file

    African Journals Online (AJOL)

    IK

    The study also found out that one of the reasons for this false teaching is because the verses and passages of ... hermeneutics, exegeses, homiletics and use of Bible resources such as Bible dictionary, ... human race makes giant strides in science and technology, the tendency is to shift away from religion. However, these ...

  8. The perceptions of students on gender equality | Nkosi | Gender and ...

    African Journals Online (AJOL)

    The study is about the perceptions of University of Venda students regarding gender equality. South Africa has made significant strides in relation to gender mainstreaming. In addition to the constitution, there are many policies that have been developed and adopted to ensure fair and equal treatment of women. However ...

  9. Status of (US) High Energy Physics Networking

    International Nuclear Information System (INIS)

    Montgomery, H.E.

    1987-02-01

    The current status of Networking to and between computers used by the High Energy Physics community is discussed. Particular attention is given to developments over the last year and to future prospects. Comparison between the current status and that of two years ago indicates that considerable strides have been made but that much remains to be done to achieve an acceptable level of functionality

  10. Reflections

    Indian Academy of Sciences (India)

    It is the physicists who have been thrown most violently off stride, who have left academic pursuits for the ... increasingly necessary for progress, and the effort to bridge between disciplines is correspondingly superficial. Professionally our methods of transmitting and reviewing the results of research are generations old and ...

  11. A Treatment-Refractory Case of Social Anxiety Disorder: Lessons Learned from a Failed Course of Cognitive-Behavioral Therapy

    Science.gov (United States)

    Brozovich, Faith A.; Heimberg, Richard G.

    2011-01-01

    Over the past 25 years researchers have made enormous strides in the implementation of cognitive-behavioral therapy (CBT) for social anxiety disorder (SAD), although considerable work remains to be done. The present paper discusses a treatment refractory case seen in our clinic. The young man presented numerous interrelated obstacles, such as low…

  12. Airway Clearance Techniques (ACTs)

    Medline Plus

    Full Text Available ... the lives of people with CF. Help us by raising awareness of CF, participating in a fundraising event, or volunteering with your local chapter. DONATE YOUR TIME FIND A CLINICAL TRIAL FIND A LOCAL CHAPTER Great Strides Participate in ...

  13. Conflicten over Haagse Stadsbeelden : Van Willemspark tot Spuiforum

    NARCIS (Netherlands)

    Oorschot, L.M.

    2014-01-01

    This study is about the continual stride between 1860 and 2010 amongst the various interest groups involved with what the city of The Hague should look like. The thesis of the study states that the fragmented image that people in the city have or experience is the result of the wide variety of urban

  14. TKA patients with unsatisfying knee function show changes in neuromotor synergy pattern but not joint biomechanics.

    Science.gov (United States)

    Ardestani, Marzieh M; Malloy, Philip; Nam, Denis; Rosenberg, Aaron G; Wimmer, Markus A

    2017-12-01

    Nearly 20% of patients who have undergone total knee arthroplasty (TKA) report persistent poor knee function. This study explores the idea that, despite similar knee joint biomechanics, the neuro-motor synergies may be different between high-functional and low-functional TKA patients. We hypothesized that (1) high-functional TKA recruit a more complex neuro-motor synergy pattern compared to low-functional TKA and (2) high-functional TKA patients demonstrate more stride-to-stride variability (flexibility) in their synergies. Gait and electromyography (EMG) data were collected during level walking for three groups of participants: (i) high-functional TKA patients (n=13); (ii) low-functional TKA patients (n=13) and (iii) non-operative controls (n=18). Synergies were extracted from EMG data using non-negative matrix factorization. Analysis of variance and Spearman correlation analyses were used to investigate between-group differences in gait and neuro-motor synergies. Results showed that synergy patterns were different among the three groups. Control subjects used 5-6 independent neural commands to execute a gait cycle. High functional TKA patients used 4-5 independent neural commands while low-functional TKA patients relied on only 2-3 independent neural commands to execute a gait cycle. Furthermore, stride-to-stride variability of muscles' response to the neural commands was reduced up to 15% in low-functional TKAs compared to the other two groups. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Exposition and Synthesis of Benin Bronze Casting: Emphasis on the Olotan Casters of Benin

    Science.gov (United States)

    Ifeta, Chris Funke

    2016-01-01

    The introduction of Western education to Nigeria has brought in its wake great strides toward development. Changes in Benin dates far back to the dawn of the 20th century. This paper investigates the critical role of education in development. The paper integrates interview data collected from bronze casters in Benin. The first section of the paper…

  16. An Exploration of Identity and Career Development of African American Women in Higher Education Leadership: Does Hair Style Make a Difference?

    Science.gov (United States)

    Farley, Yasmine Osir

    2016-01-01

    African American women, a group that endures the intersectionality of being both a woman and an African American, have many obstacles in their path as they advance in their career. Despite the strides that have been made in America to improve things for women and people of color, the interwoven societal standards of beauty do not include African…

  17. OECD Reviews of Evaluation and Assessment in Education: Romania 2017

    Science.gov (United States)

    Kitchen, Hannah; Fordham, Elizabeth; Henderson, Kirsteen; Looney, Anne; Maghnouj, Soumaya

    2017-01-01

    Romania's education system has made impressive strides over the past two decades, with an increasing share of students mastering the basic competencies that they need for life and work. But these average improvements mask significant disparities in learning outcomes and attainment, with an increasing share of students leaving education early…

  18. Reliability and concurrent validity of an alternative method of lateral ...

    African Journals Online (AJOL)

    1 University of Northern Iowa, Division of Athletic Training, 003C Human. Performance Center, Cedar Falls, Iowa, USA ... sport, only around five per cent of elite players are unavailable to play due to injury at any given time. ... place undue stress on the pars interarticularis during the delivery stride due to large contralateral ...

  19. The Effects of Muscular Fatigue on the Kinetics of Sprint Running.

    Science.gov (United States)

    Sprague, Paul; Mann, Ralph V.

    1983-01-01

    To compare the kinematic and kinetic effects of fatigue on the biomechanics of sprint running, male subjects were filmed performing a short maximal exertion sprint and a long fatiguing sprint. Observable differences in the productive muscular activity of the better and the poorer sprinters occurred during the ground-phase of their strides.…

  20. Age-related decline of gait variability in children with attention-deficit/hyperactivity disorder: Support for the maturational delay hypothesis in gait.

    Science.gov (United States)

    Manicolo, Olivia; Grob, Alexander; Lemola, Sakari; Hagmann-von Arx, Priska

    2016-02-01

    Previous findings showed a tendency toward higher gait variability in children with attention-deficit/hyperactivity disorder (ADHD) compared to controls. This study examined whether gait variability in children with ADHD eventually approaches normality with increasing age (delay hypothesis) or whether these gait alterations represent a persistent deviation from typical development (deviation hypothesis). This cross-sectional study compared 30 children with ADHD (25 boys; Mage=10 years 11 months, range 8-13 years; n=21 off medication, n=9 without medication) to 28 controls (25 boys; Mage=10 years 10 months, range 8-13 years). Gait parameters (i.e. velocity and variability in stride length and stride time) were assessed using an electronic walkway system (GAITRite) while children walked at their own pace. Children with ADHD walked with significantly higher variability in stride time compared to controls. Age was negatively associated with gait variability in children with ADHD such that children with higher age walked with lower variability, whereas in controls there was no such association. Children with ADHD displayed a less regular gait pattern than controls, indicated by their higher variability in stride time. The age-dependent decrease of gait variability in children with ADHD showed that gait performance became more regular with age and converged toward that of typically developing children. These results may reflect a maturational delay rather than a persistent deviation of gait regularity among children with ADHD compared to typically developing children. Copyright © 2015 Elsevier B.V. All rights reserved.