Sample records for unipedal stance time

  1. Effect of expertise in shooting and Taekwondo on bipedal and unipedal postural control isolated or concurrent with a reaction-time task.

    PubMed

    Negahban, Hossein; Aryan, Najmolhoda; Mazaheri, Masood; Norasteh, Ali Asghar; Sanjari, Mohammad Ali

    2013-06-01

    It was hypothesized that training in 'static balance' or 'dynamic balance' sports has differential effects on postural control and its attention demands during quiet standing. In order to test this hypothesis, two groups of female athletes practicing shooting, as a 'static balance' sport, and Taekwondo, as a 'dynamic balance' sport, and a control group of non-physically active females voluntarily participated in this study. Postural control was assessed during bipedal and unipedal stance with and without performing a Go/No-go reaction time task. Visual and/or support surface conditions were manipulated in bipedal and unipedal stances in order to modify postural difficulty. Mixed model analysis of variance was used to determine the effects of dual tasking on postural and cognitive performance. Similar pattern of results were found in bipedal and unipedal stances, with Taekwondo practitioners displaying larger sway, shooters displaying lower sway and non-athletes displaying sway characteristics intermediate to Taekwondo and shooting athletes. Larger effect was found in bipedal stance. Single to dual-task comparison of postural control showed no significant effect of mental task on sway velocity in shooters, indicating less cognitive effort invested in balance control during bipedal stance. We suggest that expertise in shooting has a more pronounced effect on decreased sway in static balance conditions. Furthermore, shooters invest less attention in postures that are more specific to their training, i.e. bipedal stance. PMID:23245642

  2. Force-controlled biting alters postural control in bipedal and unipedal stance.

    PubMed

    Ringhof, S; Stein, T; Potthast, W; Schindler, H-J; Hellmann, D

    2015-03-01

    Human posture is characterised by inherent body sway which forces the sensory and motor systems to counter the destabilising oscillations. Although the potential of biting to increase postural stability has recently been reported, the mechanisms by which the craniomandibular system (CMS) and the motor systems for human postural control are functionally coupled are not yet fully understood. The purpose of our study was, therefore, to investigate the effect of submaximum biting on postural stability and on the kinematics of the trunk and head. Twelve healthy young adults performed force-controlled biting (FB) and non-biting (NB) during bipedal narrow stance and single-leg stance. Postural stability was quantified on the basis of centre of pressure (COP) displacements, detected by use of a force platform. Trunk and head kinematics were investigated by biomechanical motion analysis, and bite forces were measured using a hydrostatic system. The results revealed that FB significantly improved postural control in terms of reduced COP displacements, providing additional evidence for the functional coupling of the CMS and human posture. Our study also showed, for the first time, that reductions in the sway of the COP were accompanied by reduced trunk and head oscillations, which might be attributable to enhanced trunk stiffness during FB. This physiological response to isometric activation of the masticatory muscles raises questions about the potential of oral motor activity as a strategy to reduce the risk of falls among the elderly or among patients with compromised postural control. PMID:25354425

  3. Effects of focal ankle joint cooling on unipedal static balance in individuals with and without chronic ankle instability.

    PubMed

    Kim, Kyung-Min; Hart, Joseph M; Saliba, Susan A; Hertel, Jay

    2015-01-01

    Application of cryotherapy over an injured joint has been shown to improve muscle function, yet it is unknown how ankle cryotherapy affects postural control. Our purpose was to determine the effects of a 20-min focal ankle joint cooling on unipedal static stance in individuals with and without chronic ankle instability (CAI). Fifteen young subjects with CAI (9 males, 6 females) and 15 healthy gender-matched controls participated. All subjects underwent two intervention sessions on different days in which they had a 1.5L plastic bag filled with either crushed ice (active treatment) or candy corn (sham) applied to the ankle. Unipedal stance with eyes closed for 10s were assessed with a forceplate before and after each intervention. Center of pressure (COP) data were used to compute 10 specific dependent measures including velocity, area, standard deviation (SD), and percent range of COP excursions, and mean and SD of time-to-boundary (TTB) minima in the anterior-posterior (AP) and mediolateral directions. For each measure a three-way (Group-Intervention-Time) repeated ANOVAs found no significant interactions and main effects involving intervention (all Ps > 0.05). There were group main effects found for mean velocity (F(1,28) = 6.46, P = .017), area (F(1,28) = 12.83, P = .001), and mean of TTB minima in the AP direction (F(1,28) = 5.19, P = .031) indicating that the CAI group demonstrated greater postural instability compared to the healthy group. Postural control of unipedal stance was not significantly altered following focal ankle joint cooling in groups both with and without CAI. Ankle joint cryotherapy was neither beneficial nor harmful to single leg balance. PMID:25468685

  4. A cane reduces loss of balance in patients with peripheral neuropathy: Results from a challenging unipedal balance test

    Microsoft Academic Search

    James A. Ashton-Miller; Mark W. L. Yeh; James K. Richardson; Todd Galloway

    1996-01-01

    Objective: To test the hypothesis that use of a cane in the nondominant hand during challenging balance tasks would significantly decrease loss of balance in patients with peripheral neuropathy while transferring from bipedal to unipedal stance on an unsteady surface.Design: Nonrandomized control study.Setting: Tertiary-care institution.Participants Eight consecutive patients with peripheral neuropathy (PN) and eight age- and gender-matched controls (C) with

  5. Intraarticular injection of hyaluronan prevents cartilage erosion, periarticular fibrosis and mechanical allodynia and normalizes stance time in murine knee osteoarthritis

    PubMed Central

    2011-01-01

    Introduction Intraarticular hyaluronan (HA) is used clinically for symptomatic relief in patients with knee osteoarthritis (OA); however, the mechanism of action is unclear. In this study, we examined the effects of a single injection of HA on joint tissue pathology, mechanical allodynia and gait changes (measured by stride times) in a murine model of OA. Methods OA was induced in the right knee joint (stifle) of 12-week-old male C57BL/6 mice by transforming growth factor ?1 (TGF?1) injection and treadmill running for 14 days. Gait parameters were quantified by using TreadScan, mechanical allodynia was evaluated with von Frey filaments, and joint pathology was evaluated by scoring of macroscopic images for both cartilage erosion and periarticular fibrosis. HA or saline control was injected 1 day after TGF?1 injection but before the start of treadmill running. Results OA development in this model was accompanied by significant (P < 0.01) enhancement of the stance and propulsion times of affected legs. HA injection (but not saline injection) blocked all gait changes and also protected joints from femoral cartilage erosion as well as tibial and femoral tissue fibrosis. Both HA injection and saline injection attenuated acute allodynia, but the HA effect was more pronounced and prolonged than the saline injection. Conclusions We conclude that videographic gait analysis is an objective, sensitive and reproducible means of monitoring joint pathology in experimental murine OA, since stance time appears to correlate directly with OA severity. A single injection of HA prevents acute and prolonged gait changes and ameliorates the cartilage erosion and periarticular fibrosis normally seen in this model. We speculate that the capacity of HA to prevent cartilage erosion results from its normalization of joint biomechanics and its inhibitory effects on periarticular cells, which are involved in tissue hyperplasia and fibrosis. This effect of exogenous HA appears to mimic the protective effects of ablation of Adamts5 (a disintegrin and metalloproteinase with thrombospondin motifs 5) on experimental murine OA, and we speculate that a common mechanism is involved. PMID:21418601

  6. Time course of 'set'-related changes in muscle responses to stance perturbation in humans.

    PubMed Central

    Schieppati, M; Nardone, A

    1995-01-01

    1. In standing subjects, toe-down rotation of a supporting platform elicits a medium-latency response (MLR) in tibialis anterior (TA) muscle and a long-latency response (LLR) in soleus (Sol). Toe-up rotation induces a short-latency response (SLR) in Sol and a LLR in TA. When subjects steadily hold onto a stable frame, all responses are decreased, except Sol SLR. The aim of this investigation was to assess whether the response modulation is dependent on information from the hand touching the frame, or whether it anticipates the holding task. 2. The time course of the changes in response amplitude was studied in a time interval centred around the act of holding, performed in a reaction-time mode. Subjects kept their extended arm close to the frame in front of them and brought the hand in contact with the frame in response to a visual go-signal. The platform was moved at different intervals prior to or after the go-signal. Surface EMGs of Sol, TA and deltoid (Delt) were recorded. 3. TA MLR began to decrease when the platform was displaced at an interval of 140 ms after the go-signal, about 200 ms before subjects touched the frame and 120 ms before termination of Delt EMG. Four hundred milliseconds after the go-signal the response reached and maintained maximal inhibition, similar to that occurring under the stationary holding condition. The time course of inhibition of Sol LLR and TA LLR was similar to that of TA MLR, except that LLRs began to decrease at an earlier interval. Due to the different response latency from the onset of the perturbations, the beginning of inhibition of both MLRs and LLRs occurred almost simultaneously. 4. The changes in amplitude of leg muscle responses are not triggered by the go-signal, contact with the frame, or arm motion, suggesting that the modulation is related to the transition to a new, stabilized postural 'set'. The similar extent and parallel time course of MLR and LLR suppression, possibly transmitted through different pathways, points to the spinal cord as the site of action. The lack of depression of the monosynaptic SLR suggests an effect at premotoneuronal level. On the basis of selectivity, latency and time course of the effect, we favour the hypothesis that a monoaminergic pathway from the brainstem is involved. PMID:8544139

  7. Time-dependent influence of sensorimotor set on automatic responses in perturbed stance

    NASA Technical Reports Server (NTRS)

    Chong, R. K.; Horak, F. B.; Woollacott, M. H.; Peterson, B. W. (Principal Investigator)

    1999-01-01

    These experiments tested the hypothesis that the ability to change sensorimotor set quickly for automatic responses depends on the time interval between successive surface perturbations. Sensorimotor set refers to the influence of prior experience or context on the state of the sensorimotor system. Sensorimotor set for postural responses was influenced by first giving subjects a block of identical backward translations of the support surface, causing forward sway and automatic gastrocnemius responses. The ability to change set quickly was inferred by measuring the suppression of the stretched antagonist gastrocnemius responses to toes-up rotations causing backward sway, following the translations. Responses were examined under short (10-14 s) and long (19-24 s) inter-trial intervals in young healthy subjects. The results showed that subjects in the long-interval group changed set immediately by suppressing gastrocnemius to 51% of translation responses within the first rotation and continued to suppress them over succeeding rotations. In contrast, subjects in the short-interval group did not change set immediately, but required two or more rotations to suppress gastrocnemius responses. By the last rotation, the short-interval group suppressed gastrocnemius responses to 33%, similar to the long-interval group of 29%. Associated surface plantarflexor torque resulting from these responses showed similar results. When rotation and translation perturbations alternated, however, the short-interval group was not able to suppress gastrocnemius responses to rotations as much as the long-interval group, although they did suppress more than in the first rotation trial after a series of translations. Set for automatic responses appears to linger, from one trial to the next. Specifically, sensorimotor set is more difficult to change when surface perturbations are given in close succession, making it appear as if set has become progressively stronger. A strong set does not mean that responses become larger over consecutive trials. Rather, it is inferred by the extent of difficulty in changing a response when it is appropriate to do so. These results suggest that the ability to change sensorimotor set quickly is sensitive to whether the change is required after a long or a short series of a prior different response, which in turn depends on the time interval between successive trials. Different rate of gastrocnemius suppression to toes-up rotation of the support surface have been reported in previous studies. This may be partially explained by different inter-trial time intervals demonstrated in this study.

  8. NOAAINMFS Developments Japan Eases Stance

    E-print Network

    NOAAINMFS Developments Japan Eases Stance on U.S. Fish Imports The Japanese government has taken important steps to make it eas- ier for the U.S. fishing industry to ex- port seafood products to Japan, ac Fisheries Agency officials and Japanese fishing industry representa- tives to review steps taken by Japan

  9. Comparison of Human and Humanoid Robot Control of Upright Stance

    PubMed Central

    Peterka, Robert J.

    2009-01-01

    There is considerable recent interest in developing humanoid robots. An important substrate for many motor actions in both humans and biped robots is the ability to maintain a statically or dynamically stable posture. Given the success of the human design, one would expect there are lessons to be learned in formulating a postural control mechanism for robots. In this study we limit ourselves to considering the problem of maintaining upright stance. Human stance control is compared to a suggested method for robot stance control called zero moment point (ZMP) compensation. Results from experimental and modeling studies suggest there are two important subsystems that account for the low- and mid-frequency (DC to ~1 Hz) dynamic characteristics of human stance control. These subsystems are 1) a “sensory integration” mechanism whereby orientation information from multiple sensory systems encoding body kinematics (i.e. position, velocity) is flexibly combined to provide an overall estimate of body orientation while allowing adjustments (sensory re-weighting) that compensate for changing environmental conditions, and 2) an “effort control” mechanism that uses kinetic-related (i.e., force-related) sensory information to reduce the mean deviation of body orientation from upright. Functionally, ZMP compensation is directly analogous to how humans appear to use kinetic feedback to modify the main sensory integration feedback loop controlling body orientation. However, a flexible sensory integration mechanism is missing from robot control leaving the robot vulnerable to instability in conditions were humans are able to maintain stance. We suggest the addition of a simple form of sensory integration to improve robot stance control. We also investigate how the biological constraint of feedback time delay influences the human stance control design. The human system may serve as a guide for improved robot control, but should not be directly copied because the constraints on robot and human control are different. PMID:19665564

  10. Effect of stance position on kick performance in taekwondo.

    PubMed

    Estevan, Isaac; Jandacka, Daniel; Falco, Coral

    2013-01-01

    In taekwondo, the stance position can potentially affect kick performance. The aim of this study was to analyse mechanical variables in the roundhouse kick in taekwondo according to three stance positions (0°, 45°, 90°). Nine experienced taekwondo athletes performed consecutive kicking trials in a random order according to these three relative positions of the feet on the ground. Measurements for the mechanical analysis were performed using two 3D force plates and an eight-camera motion capture system. The taekwondo athletes' reaction and execution times were shorter when starting from the 0° and 45° stance positions than from the 90° position (P < 0.05). Moreover, the ground reaction force was negatively correlated with execution time and positively with velocity of thigh and shank. Our results suggest that the stance position affects the execution technique of taekwondo athletes' kicks. It is suggested that athletes should not adopt the 90° stance position because it will not enable them to achieve the best performance in the roundhouse kick. PMID:23879570

  11. The Collective Stance in Modeling Expertise in Individuals and Organizations

    Microsoft Academic Search

    Brian R. Gaines

    1994-01-01

    This paper is concerned with modeling the nature of expertise and its role in society in relation to research on expert systems and enterprise models. It argues for the adoption of a collective stance in which the human species is viewed as a single organism recursively partitioned in space and time into sub-organisms that are similar to the whole. These

  12. Five Stances That Have Got to Go

    ERIC Educational Resources Information Center

    Zeigler, Earle F.

    1973-01-01

    The five stances in physical education that have to go are as follows: a) the shotgun approach'' to professional preparation; b) the athletics uber alles approach''; c) the women are all right in their place approach''; d) the body of knowledge approach'' and the password is treadmill' approach.''

  13. Narrative Stance in the Douglass Autobiographies.

    ERIC Educational Resources Information Center

    Davidson, Phebe

    To consider Frederick Douglass as an autobiographer, it is useful to examine each of his three autobiographical texts with a view to drawing some conclusion about their relation to one another, and about the relation of the author to each one. It seems likely that the shifting of Douglass' narrative stance is an index of his intellectual…

  14. Assessing Muscle Stiffness from Quiet Stance in Parkinson's Disease

    E-print Network

    Assessing Muscle Stiffness from Quiet Stance in Parkinson's Disease Michael Lauk 1;2;4 , MSc Stiffness from Quiet Stance: Applicability to Parkinson's Disease Abstract In previous studies, we developed this measure to patients with Parkinson's disease (PD). We correlated the postural stiffness measure

  15. The Effects of Argument Stance on Scientific Knowledge Inquiry Skills

    Microsoft Academic Search

    Ruey-Yun Horng; Po-Hui Lu; Pei-Hua Chen; Shih-Huan Hou

    2012-01-01

    This study investigates the effects of argument stance on knowledge inquiry skills. Sixty-two participants were assigned to three argument stance conditions (proponent, opponent, or control) to receive scaffolded argumentation practice on two science issues in random order. After the argumentation treatment, participants were asked to write down their own opinions regarding the claim. Their responses were analysed according to argument

  16. Soleus H-reflex modulation during receive stance in badminton players in the receive stance

    PubMed Central

    Masu, Yujiro; Muramatsu, Ken

    2015-01-01

    [Purpose] This study aimed to clarify the characteristics of motor neuron excitability by examining the soleus H-reflex in the ready position adopted immediately before making a return during badminton games. [Subjects] Sixteen individuals with (badminton group) and 16 without (control group) experience of playing badminton were studied. [Methods] Each subject was instructed to take up various stances for returning a shuttlecock to measure the H- and M-waves in the soleus. [Results] The H-wave was significantly decreased when gripping a racket was held in the dominant hand than compared to just standing in the badminton group. In contrast, in the control group, no significant differences were observed between when standing and the other stances. [Conclusion] Based on these results, the excitability of spinal motor neurons may have been reduced (H-wave suppression) by badminton training to increase the instantaneous force (power training). PMID:25642054

  17. Soleus H-reflex modulation during receive stance in badminton players in the receive stance.

    PubMed

    Masu, Yujiro; Muramatsu, Ken

    2015-01-01

    [Purpose] This study aimed to clarify the characteristics of motor neuron excitability by examining the soleus H-reflex in the ready position adopted immediately before making a return during badminton games. [Subjects] Sixteen individuals with (badminton group) and 16 without (control group) experience of playing badminton were studied. [Methods] Each subject was instructed to take up various stances for returning a shuttlecock to measure the H- and M-waves in the soleus. [Results] The H-wave was significantly decreased when gripping a racket was held in the dominant hand than compared to just standing in the badminton group. In contrast, in the control group, no significant differences were observed between when standing and the other stances. [Conclusion] Based on these results, the excitability of spinal motor neurons may have been reduced (H-wave suppression) by badminton training to increase the instantaneous force (power training). PMID:25642054

  18. Effect of stance width on multidirectional postural responses

    NASA Technical Reports Server (NTRS)

    Henry, S. M.; Fung, J.; Horak, F. B.; Peterson, B. W. (Principal Investigator)

    2001-01-01

    The effect of stance width on postural responses to 12 different directions of surface translations was examined. Postural responses were characterized by recording 11 lower limb and trunk muscles, body kinematics, and forces exerted under each foot of 7 healthy subjects while they were subjected to horizontal surface translations in 12 different, randomly presented directions. A quasi-static approach of force analysis was done, examining force integrals in three different epochs (background, passive, and active periods). The latency and amplitude of muscle responses were quantified for each direction, and muscle tuning curves were used to determine the spatial activation patterns for each muscle. The results demonstrate that the horizontal force constraint exerted at the ground was lessened in the wide, compared with narrow, stance for humans, a similar finding to that reported by Macpherson for cats. Despite more trunk displacement in narrow stance, there were no significant changes in body center of mass (CoM) displacement due to large changes in center of pressure (CoP), especially in response to lateral translations. Electromyographic (EMG) magnitude decreased for all directions in wide stance, particularly for the more proximal muscles, whereas latencies remained the same from narrow to wide stance. Equilibrium control in narrow stance was more of an active postural strategy that included regulating the loading/unloading of the limbs and the direction of horizontal force vectors. In wide stance, equilibrium control relied more on an increase in passive stiffness resulting from changes in limb geometry. The selective latency modulation of the proximal muscles with translation direction suggests that the trunk was being actively controlled in all directions. The similar EMG latencies for both narrow and wide stance, with modulation of only the muscle activation magnitude as stance width changed, suggest that the same postural synergy was only slightly modified for a change in stance width. Nevertheless, the magnitude of the trunk displacement, as well as of CoP displacement, was modified based on the degree of passive stiffness in the musculoskeletal system, which increased with stance width. The change from a more passive to an active horizontal force constraint, to larger EMG magnitudes especially in the trunk muscles and larger trunk and CoP excursions in narrow stance are consistent with a more effortful response for equilibrium control in narrow stance to perturbations in all directions.

  19. EMG responses to maintain stance during multidirectional surface translations

    NASA Technical Reports Server (NTRS)

    Henry, S. M.; Fung, J.; Horak, F. B.; Peterson, B. W. (Principal Investigator)

    1998-01-01

    To characterize muscle synergy organization underlying multidirectional control of stance posture, electromyographic activity was recorded from 11 lower limb and trunk muscles of 7 healthy subjects while they were subjected to horizontal surface translations in 12 different, randomly presented directions. The latency and amplitude of muscle responses were quantified for each perturbation direction. Tuning curves for each muscle were examined to relate the amplitude of the muscle response to the direction of surface translation. The latencies of responses for the shank and thigh muscles were constant, regardless of perturbation direction. In contrast, the latencies for another thigh [tensor fascia latae (TFL)] and two trunk muscles [rectus abdominis (RAB) and erector spinae (ESP)] were either early or late, depending on the perturbation direction. These three muscles with direction-specific latencies may play different roles in postural control as prime movers or as stabilizers for different translation directions, depending on the timing of recruitment. Most muscle tuning curves were within one quadrant, having one direction of maximal activity, generally in response to diagonal surface translations. Two trunk muscles (RAB and ESP) and two lower limb muscles (semimembranosus and peroneus longus) had bipolar tuning curves, with two different directions of maximal activity, suggesting that these muscle can play different roles as part of different synergies, depending on translation direction. Muscle tuning curves tended to group into one of three regions in response to 12 different directions of perturbations. Two muscles [rectus femoris (RFM) and TFL] were maximally active in response to lateral surface translations. The remaining muscles clustered into one of two diagonal regions. The diagonal regions corresponded to the two primary directions of active horizontal force vector responses. Two muscles (RFM and adductor longus) were maximally active orthogonal to their predicted direction of maximal activity based on anatomic orientation. Some of the muscles in each of the synergic regions were not anatomic synergists, suggesting a complex central organization for recruitment of muscles. The results suggest that neither a simple reflex mechanism nor a fixed muscle synergy organization is adequate to explain the muscle activation patterns observed in this postural control task. Our results are consistent with a centrally mediated pattern of muscle latencies combined with peripheral influence on muscle magnitude. We suggest that a flexible continuum of muscle synergies that are modifiable in a task-dependent manner be used for equilibrium control in stance.

  20. Stance leg control: variation of leg parameters supports stable hopping.

    PubMed

    Riese, Sebastian; Seyfarth, Andre

    2012-03-01

    The spring-loaded inverted pendulum describes the planar center-of-mass dynamics of legged locomotion. This model features linear springs with constant parameters as legs. In biological systems, however, spring-like properties of limbs can change over time. Therefore, in this study, it is asked how variation of spring parameters during ground contact would affect the dynamics of the spring-mass model. Neglecting damping initially, it is found that decreasing stiffness and increasing rest length of the leg during a stance phase are required for orbitally stable hopping. With damping, stable hopping is found for a larger region of rest-length rates and stiffness rates. Here, also increasing stiffness and decreasing rest length can result in stable hopping. Within the predicted range of leg parameter variations for stable hopping, there is no need for precise parameter tuning. Since hopping gaits form a subset of the running gaits (with vanishing horizontal velocity), these results may help to improve leg design in robots and prostheses. PMID:22183256

  1. Consumer opinions of a stance control knee orthosis.

    PubMed

    Bernhardt, Kathie A; Irby, Steven E; Kaufman, Kenton R

    2006-12-01

    Stance control knee orthoses (SCOs) have become very popular recently. However, there is little information regarding opinions of actual orthosis users. The purpose of this study was to quantify the users' opinions of a SCO, and see whether factors found important for knee orthoses in past studies hold true for a stance control orthosis as well. A standardized survey was employed as part of a larger field trial study of the Dynamic Knee Brace System, a SCO developed by the authors. The Dynamic Knee Brace System scored well in areas of effectiveness, operability, and dependability, but areas in need of improvement included weight, cosmesis, and donning and doffing. These findings match well with previous knee orthosis studies. This study shows that wearing a stance control knee orthosis can be a positive experience for an orthosis user. PMID:17162515

  2. Language, Stance, and Identity at Selwyn Girls' High

    Microsoft Academic Search

    Katie Drager

    This paper reports on results from ethnographic work conducted at an all girls' high school in New Zealand, focusing particularly on two groupings: the common room (CR) girls, who form a constellation of practices, and the non-common room (NCR) girls, who form what I refer to as a constellation of stance. Trends in the data provide evidence that an individual's

  3. A push and a shove and the land is ours: Morrissey's counter-hegemonic stance(s) on social class

    Microsoft Academic Search

    Martin J. Power; Aileen Dillane; Eoin Devereux

    2012-01-01

    We explore how the singer Morrissey has represented the struggles of the proletariat in creative and provocative ways, inviting a deep textual reading that reveals a complex counter-hegemonic stance on the issue of social class. A champion of the ‘Other’ in a variety of guises, Morrissey is revealed in this article as a raconteur of the marginalized working class. We

  4. Balance in Astronauts Performing Jumps, Walking and Quiet Stance Following Spaceflight

    NASA Technical Reports Server (NTRS)

    Reschke, Millard F.; Bloomberg, J. J.; Wood, S. J.; Harm, D. L.

    2011-01-01

    Introduction: Both balance and locomotor ataxia is severe in astronauts returning from spaceflight with serious implications for unassisted landings. As a part of an ongoing effort to demonstrate the functional significance of the postflight ataxia problem our laboratory has evaluated jumping, walking heel-to-toe and quite stance balance immediately following spaceflight. Methods: Six astronauts from 12-16 day flights and three from 6-month flights were asked to perform three self-initiated two-footed jumps from a 30-cm-high platform, walking for 10 steps (three trials) placing the feet heel to toe in tandem, arms folded across the chest and the eyes closed, and lastly, recover from a simulated fall by standing from a prone position on the floor and with eyes open maintain a quiet stance for 3 min with arms relaxed along the side of the body and feet comfortably positioned on a force plate. Crewmembers were tested twice before flight, on landing day (short-duration), and days 1, 6, and 30 following all flight durations. Results/Conclusions: Many of astronauts tested fell on their first postflight jump but recovered by the third jump showing a rapid learning progression. Changes in take-off strategy were clearly evident in duration of time in the air between the platform and the ground (significant reduction in time to land), and also in increased asymmetry in foot latencies on take-off postflight. During the tandem heel-to-toe walking task there was a significant decrease in percentage of correct steps on landing day (short-duration crew) and on first day following landing (long-duration) with only partial recovery the following day. Astronauts for both short and long duration flight times appeared to be unaware of foot position relative to their bodies or the floor. During quite stance most of crewmembers tested exhibited increased stochastic activity (larger short-term COP diffusion coefficients postflight in all planes and increases in mean sway speed).

  5. Heel Lifts and the Stance Phase of Gait in Subjects With Limited Ankle Dorsiflexion

    PubMed Central

    Johanson, Marie A; Cooksey, Alanna; Hillier, Caroline; Kobbeman, Heather; Stambaugh, Amy

    2006-01-01

    Context: Heel lifts are often prescribed as part of the treatment program for patients with overuse injuries associated with limited ankle dorsiflexion. However, little is known about how joint kinematics and temporal variables are affected by heel lifts. Objective: To determine the effects of heel lifts on selected lower extremity kinematic and temporal variables during the stance phase of gait in subjects with limited ankle dorsiflexion. Design: Two-way, fully repeated-measures design. The 2 factors were side (right or left) and walking condition (shoes alone, 6-mm heel lifts in shoes, 9-mm heel lifts in shoes). Setting: University biomechanics laboratory. Patients or Other Participants: Twenty-six volunteers (21 females, 5 males) with no more than 5° of ankle joint dorsiflexion. Intervention(s): Subjects were tested in shoes alone and in shoes with 6-mm and 9-mm heel lifts. Main Outcome Measure(s): We used the Qualisys Motion Analysis System to measure ankle dorsiflexion excursion, maximal knee extension, and time to heel off during the stance phase of gait under the 3 walking conditions. Results: On the right side, ankle dorsiflexion excursion increased significantly with the 6-mm and 9-mm heel lifts compared with shoes alone ( P < .05). On the left side, ankle dorsiflexion increased significantly with the 9-mm heels lifts over shoes alone and with the 9-mm heel lifts compared with the 6-mm heel lifts ( P < .05). Time to heel off increased significantly for walking with the 9-mm heel lifts compared with shoes alone ( P < .05). No differences were noted for maximal knee extension ( P > .05). Conclusions: Clinicians may consider prescribing heel lifts for patients with limited dorsiflexion range of motion if increasing ankle dorsiflexion excursion and time to heel off during the stance phase of gait may be beneficial. PMID:16791300

  6. Stance width changes how sensory feedback is used for multisegmental balance control.

    PubMed

    Goodworth, Adam D; Mellodge, Patricia; Peterka, Robert J

    2014-08-01

    A multilink sensorimotor integration model of frontal plane balance control was developed to determine how stance width influences the use of sensory feedback in healthy adults. Data used to estimate model parameters came from seven human participants who stood on a continuously rotating surface with three different stimulus amplitudes, with eyes open and closed, and at four different stance widths. Dependent variables included lower body (LB) and upper body (UB) sway quantified by frequency-response functions. Results showed that stance width had a major influence on how parameters varied across stimulus amplitude and between visual conditions. Active mechanisms dominated LB control. At narrower stances, with increasing stimulus amplitude, subjects used sensory reweighting to shift reliance from proprioceptive cues to vestibular and/or visual cues that oriented the LB more toward upright. When vision was available, subjects reduced reliance on proprioception and increased reliance on vision. At wider stances, LB control did not exhibit sensory reweighting. In the UB system, both active and passive mechanisms contributed and were dependent on stance width. UB control changed across stimulus amplitude most in wide stance (opposite of the pattern found in LB control). The strong influence of stance width on sensory integration and neural feedback control implies that rehabilitative therapies for balance disorders can target different aspects of balance control by using different stance widths. Rehabilitative strategies designed to assess or modify sensory reweighting will be most effective with the use of narrower stances, whereas wider stances present greater challenges to UB control. PMID:24760788

  7. The cat vertebral column: stance configuration and range of motion

    NASA Technical Reports Server (NTRS)

    Macpherson, J. M.; Ye, Y.; Peterson, B. W. (Principal Investigator)

    1998-01-01

    This study examined the configuration of the vertebral column of the cat during independent stance and in various flexed positions. The range of motion in the sagittal plane is similar across most thoracic and lumbar joints, with the exception of a lesser range at the transition region from thoracic-type to lumbar-type vertebrae. The upper thoracic column exhibits most of its range in dorsiflexion and the lower thoracic and lumbar in ventroflexion. Lateral flexion is limited to less than 5 degrees at all segments. The range in torsion is almost 180 degrees and occurs primarily in the midthoracic region, T4-T11. Contrary to the depiction in most atlases, the standing cat exhibits several curvatures, including a mild dorsiflexion in the lower lumbar segments, a marked ventroflexion in the lower thoracic and upper lumbar segments, and a profound dorsiflexion in the upper thoracic (above T9) and cervical segments. The curvatures are not significantly changed by altering stance distance but are affected by head posture. During stance, the top of the scapula lies well above the spines of the thoracic vertebrae, and the glenohumeral joint is just below the bodies of vertebrae T3-T5. Using a simple static model of the vertebral column in the sagittal plane, it was estimated that the bending moment due to gravity is bimodal with a dorsiflexion moment in the lower thoracic and lumbar region and a ventroflexion moment in the upper thoracic and cervical region. Given the bending moments and the position of the scapula during stance, it is proposed that two groups of scapular muscles provide the major antigravity support for the head and anterior trunk. Levator scapulae and serratus ventralis form the lateral group, inserting on the lateral processes of cervical vertebrae and on the ribs. The major and minor rhomboids form the medial group, inserting on the spinous tips of vertebrae from C4 to T4. It is also proposed that the hypaxial muscles, psoas major, minor, and quadratus lumborum could support the lumbar trunk during stance.

  8. Use of wavelet coherence to assess two-joint coordination during quiet upright stance.

    PubMed

    Zhang, Hongbo; Nussbaum, Maury A; Agnew, Michael J

    2014-10-01

    Joint coordination plays a critical role in maintaining postural stability, yet there is limited existing work describing joint coordination patterns in the time-frequency domain. Here, two-joint coordination was examined during quiet upright stance. A wavelet coherence method was applied to quantify the coherence between ankle-trunk and ankle-head angles in the sagittal and frontal planes. Wavelet coherence results indicated intermittent joint coordination particularly for frequencies of 2.5-4.0Hz. Coherence results were further processed to estimate mean time intervals between coherence instances, coherence burst frequency, and the ratio of in-phase versus anti-phase behaviors. Time intervals between intermittent coherence were 1.3-1.5sec, coherence burst frequency was ~0.4Hz, and phase ratios were ~1.0. Intermittent "bursting" of postural muscles may account for the finding of intermittent coherence in the noted frequency band. Some age and/or gender differences in coherence were found, and may be related to comparable differences in postural control ability or strategies. Results from application of this new method support earlier evidence that kinematic coordination is achieved intermittently rather than continuously during quiet upright stance. This method may provide richer information regarding such coordination, and could be a useful approach in future studies. PMID:25073748

  9. Limb-Bone Scaling Indicates Diverse Stance and Gait in Quadrupedal Ornithischian Dinosaurs

    PubMed Central

    Maidment, Susannah C. R.; Linton, Deborah H.; Upchurch, Paul; Barrett, Paul M.

    2012-01-01

    Background The most primitive ornithischian dinosaurs were small bipeds, but quadrupedality evolved three times independently in the clade. The transition to quadrupedality from bipedal ancestors is rare in the history of terrestrial vertebrate evolution, and extant analogues do not exist. Constraints imposed on quadrupedal ornithischians by their ancestral bipedal bauplan remain unexplored, and consequently, debate continues about their stance and gait. For example, it has been proposed that some ornithischians could run, while others consider that none were cursorial. Methodology/Principal Findings Drawing on biomechanical concepts of limb bone scaling and locomotor theory developed for extant taxa, we use the largest dataset of ornithischian postcranial measurements so far compiled to examine stance and gait in quadrupedal ornithischians. Differences in femoral midshaft eccentricity in hadrosaurs and ceratopsids may indicate that hadrosaurs placed their feet on the midline during locomotion, while ceratopsids placed their feet more laterally, under the hips. More robust humeri in the largest ceratopsids relative to smaller taxa may be due to positive allometry in skull size with body mass in ceratopsids, while slender humeri in the largest stegosaurs may be the result of differences in dermal armor distribution within the clade. Hadrosaurs are found to display the most cursorial morphologies of the quadrupedal ornithischian cades, indicating higher locomotor performance than in ceratopsids and thyreophorans. Conclusions/Significance Limb bone scaling indicates that a previously unrealised diversity of stances and gaits were employed by quadrupedal ornithischians despite apparent convergence in limb morphology. Grouping quadrupedal ornithischians together as a single functional group hides this disparity. Differences in limb proportions and scaling are likely due to the possession of display structures such as horns, frills and dermal armor that may have affected the center of mass of the animal, and differences in locomotor behaviour such as migration, predator escape or home range size. PMID:22666333

  10. Visual information and multi-joint coordination patterns in one-leg stance.

    PubMed

    Wang, Zheng; Molenaar, Peter C M; Challis, John H; Jordan, Kimberlee; Newell, Karl M

    2014-03-01

    This study examined the influence of visual information on the multi-joint coordination patterns in maintaining one-leg stance. 12 participants stood still on their left leg for two 1 min trials with and without visual information. The multi-joint coordination patterns in the frontal plane were examined using a frequency domain principal component analysis (PCAf) on 14 joint angular motion time series. The factor loading spectra of PC1 showed two distinct multi-joint postural coordination strategies that relate to the mechanical constraints on balance identified by Hof (2007) [7]. The more prevalent strategy was the coordination of the left ankle-left knee or the left ankle only motion that is related to the "moving the center of pressure" strategy. A 2nd multi-joint coordination strategy showed larger factor loading of the trunk and upper limbs (i.e., shoulders and elbows) in addition to the left ankle implying the role of the upper limbs to generate "counter-rotational torque against the sway of the center of mass (COM)". With eyes open, the participants predominantly utilized the 1st strategy to maintain balance but switched to the 2nd strategy when visual information was not available during the stance. The role of visual information in determining the prevalence of two dominant multi-joint coordination kinematic patterns in one-leg stance reflects the redundant and emergent properties of the postural control system that channel the biomechanical constraints on balance arising from the interaction of the task, environment and the individual. PMID:24388780

  11. Otolith function assessed with the subjective postural horizontal and standardised stance and gait tasks.

    PubMed

    Beule, A G; Allum, J H J

    2006-01-01

    If otolith function is essential to maintain upright standing while moving along slanted or uneven surfaces, subjects with an otolith deficit should have difficulty judging whether the inclination of the surface on which they are standing is tilted or not. We tested this judgement and compared it with the ability to control trunk sway during standardised stance and gait tests. Thirteen patients with unilateral vestibular nerve neurectomy at least 6 months prior to testing and 39 age-matched controls were asked to move a dynamic posturography platform on which they were standing back to their subjective 'horizontal' position after the platform had been slowly tilted at 0.4 degrees/s to 5 degrees in 8 different directions. Normal subjects left the platform deviated in pitch (forwards-backwards) at about 0.7 degrees on describing the platform as levelled off for all directions of tilt. Patients showed larger deviations of about 1.3 degrees in pitch with significant differences for forward right tilt (1.58+/-0.73 degrees compared to 0.73+/-0.11 degrees for normals; mean and SEM) and for forward left. Roll (lateral) deviations were about 0.4 degrees for normals and 0.5 degrees larger for the patients (for example, for backward left, 1.13+/-0.24 degrees compared to 0.4+/-0.07 degrees in normals). Except for a tendency towards greater deviations to the lesion side of patients with eyes closed, no differences were noted between tests under eyes open and closed conditions. However, for backward and roll tilts patients needed to steady themselves first by grasping a handrail when tested with eyes closed. Stance tests on foam showed increases in roll and pitch trunk sway with respect to controls. Patients had significantly larger trunk roll sway deviations during 1-legged stance tests and during gait trials. For stance trials, the patients lost their balance control prior to the end of the standard 20-second recording time. We conclude that a unilateral loss of otolith inputs due to nerve resection permanently impairs the ability to judge whether the support surface is horizontal, and leads to excessive trunk sway when standing on a compliant surface as well as excessive trunk roll sway during gait. PMID:16479089

  12. Climate Literacy for Kids: Finding Medium, Message, and Stance

    NASA Astrophysics Data System (ADS)

    Fisher, D. K.; Leon, N.; Jackson, R.; Greene, M. P.

    2011-12-01

    As part of NASA's Global Climate Change (climate.nasa.gov) website (winner of the 2011Webby Award for Best Science Site), Climate Kids (climate.nasa.gov/kids) presents positive role models for green careers and encourages kids to be good climate citizens. But before they will care, they must understand. Climate Kids helps kids understand climate science by communicating at their own science awareness and maturity level, and by giving them concrete ways to start helping Earth now. Climate Kids, as informal education, speaks to upper-elementary-school-age kids in their own language and using some of their favorite media. In addition to simple, liberally illustrated text explanations of the basic science concepts, cartoons and games reinforce the concepts in a fun way. A growing section on green careers interviews enthusiastic individuals currently practicing their professions. In explaining what they do, these individuals reinforce the climate science concepts and "how to help" suggestions elsewhere on the site. The games also reinforce the green career choices. "Green Careers" currently features a "green" general contractor, a home energy auditor, a water-wise landscaper, a recycling program educator, and a renewable energy scientist. The message of the scientist, who designs wind energy farms and "architectural wind" arrays, is reinforced by the "Power-up" game. In this game, players move a wind turbine up or down to capture the wind and move a solar array back and forth to stay out of cloud shadows. Depending on how many "windows" of the game's "city" light up using these alternative energy sources, the player earns a bronze, silver, gold, or platinum "medal." A recycling game reinforces the messages of the recycling program educator about the importance of recycling in saving energy, what can and cannot be recycled, and how long trash items remain in a landfill before decomposing. In the game, a variety of throw-away objects rains down from the top of the screen. Various recycling bins (glass, plastic, metal, and paper) are lined up on the left and right sides of the screen, with a trash bin at the bottom. As an item drops, the player must quickly decide what kind of material it is made of and whether it is recyclable, then guide it into the appropriate bin. As the rate of items entering play increases, any missed items fall into the trash and stay there for a length of time proportional to their decomposition time. If the trash bin gets full, the game is over. While enjoying the increasing challenge of the game, players learn to identify many items as recyclable that they may not have recognized as recyclable before. Another feature on Climate Kids is "Climate Tales," a slightly edgy animated cartoon series (two episodes so far) about the adventures of a blundering polar bear, a chirpy tamarin monkey, and a grumpy old fish as "accidental tourists" around the planet, observing and dealing with the environmental conditions they encounter. Fairly complex concepts (such as reasons and implications of the declining abundance of phytoplankton) are woven into the tales. Climate Kids is a fun site for kids, educational and realistic, and yet positive and hopeful-the only reasonable stance to present to this young audience.

  13. Post-effect of forward and backward locomotion on body orientation in space during quiet stance

    Microsoft Academic Search

    Alessandro Marco De Nunzio; Carlo Zanetti; Marco Schieppati

    2009-01-01

    Neural circuits responsible for stance control serve other motor tasks as well. We investigated the effect of prior locomotor\\u000a tasks on stance, hypothesizing that postural post-effects of walking are dependent on walking direction. Subjects walked forward\\u000a (WF) and backward (WB) on a treadmill. Prior to and after walking they maintained quiet stance. Ground reaction forces and\\u000a centre of foot pressure

  14. Effect of equinus foot placement and intrinsic muscle response on knee extension during stance

    E-print Network

    Effect of equinus foot placement and intrinsic muscle response on knee extension during stance J with knee hyperextension during stance. Whether there exists a causal mechanism linking equinus foot system to equinus foot placement, a forward dynamic simulation of normal walking was perturbed

  15. Risk Taking in Late Adolescence: Relations between Sociomoral Reasoning, Risk Stance, and Behavior

    ERIC Educational Resources Information Center

    Shaw, Leigh A.; Amsel, Eric; Schillo, Joshua

    2011-01-01

    This study explored relations among late adolescents' sociomoral reasoning about risk taking, risk stance, and behavior. One-hundred and thirty-two participants (18-20-year-olds) were surveyed about their own risk stance (Avoidant, Opportunistic, Curious, Risk Seeking) and behavior in three realms (Alcohol Use, Drug Use, Reckless Driving), and…

  16. Linguistic Markers of Stance in Early and Advanced Academic Writing: A Corpus-Based Comparison

    ERIC Educational Resources Information Center

    Aull, Laura L.; Lancaster, Zak

    2014-01-01

    This article uses corpus methods to examine linguistic expressions of stance in over 4,000 argumentative essays written by incoming first-year university students in comparison with the writing of upper-level undergraduate students and published academics. The findings reveal linguistic stance markers shared across the first-year essays despite…

  17. Problematising researcher–respondent relations through an exploration of communicative stance

    Microsoft Academic Search

    Adam Lefstein

    2010-01-01

    To what extent and in what ways should researchers share their views with research participants during ethnographic fieldwork? This article discusses the author's experience of adopting different communicative stances with respondents in the context of an ethnographic study of the enactment of the English National Literacy Strategy in a ‘failing’ primary school. A commonly accepted communicative stance in ethnography, according

  18. Signaling Organization and Stance: Academic Language Use in Middle Grade Persuasive Writing

    ERIC Educational Resources Information Center

    Dobbs, Christina L.

    2014-01-01

    Effective academic writing is accessible to readers because writers follow shared conventions for organization and signal their stance on particular topics; however, few specifics are known about how middle graders might develop knowledge of and use these academic language forms and functions to signal their organization and stance in persuasive…

  19. A Cross-Cultural Analysis of Stance in Disaster News Reports

    ERIC Educational Resources Information Center

    Liu, Lian; Stevenson, Marie

    2013-01-01

    This study examines stance in cross-cultural media discourse by comparing disaster news reports on the Sichuan earthquake of May 2008 in a Chinese, an Australian Chinese, and an Australian newspaper. The stance taken in the news reports is examined using the Attitude sub-system of Martin and White's (2005) Appraisal framework. The analysis…

  20. Exploring Valued Patterns of Stance in Upper-Level Student Writing in the Disciplines

    ERIC Educational Resources Information Center

    Lancaster, Zak

    2014-01-01

    Drawing on the appraisal framework from systemic functional linguistics (SFL), this article examines patterns of stance in a corpus of 92 high- and low-graded argumentative papers written in the context of an upper-level course in economics. It interprets differential patterns of stance in students' texts in light of interview commentaries…

  1. Ninth Grade Students' Negotiation of Aesthetic, Efferent, and Critical Stances in Response to a Novel Set in Afghanistan

    ERIC Educational Resources Information Center

    Taliaferro, Cheryl

    2011-01-01

    This qualitative, action research study was guided by two primary research questions. First, how do students negotiate aesthetic, efferent, and critical stances when reading a novel set in Afghanistan? Second, how do aesthetic and efferent stances contribute to or hinder the adoption of a critical stance? A large body of research exists that…

  2. The Single-Leg-Stance Test in Parkinson’s Disease

    PubMed Central

    Chomiak, Taylor; Pereira, Fernando Vieira; Hu, Bin

    2015-01-01

    Background Timed single-leg-stance test (SLST) is widely used to assess postural control in the elderly. In Parkinson’s disease (PD), it has been shown that an SLST around 10 seconds or below may be a sensitive indicator of future falls. However, despite its role in fall risk, whether SLST times around 10 seconds marks a clinically important stage of disease progression has largely remained unexplored. Methods A cross-sectional study where 27 people with PD were recruited and instructed to undertake timed SLST for both legs was conducted. Disease motor impairment was assessed with the Unified Parkinson’s Disease Rating Scale Part 3 (UPDRS-III). Results This study found that: 1) the SLST in people with PD shows good test-retest reliability; 2) SLST values can be attributed to two non-overlapping clusters: a low (10.4 ± 6.3 seconds) and a high (47.6 ± 11.7 seconds) value SLST group; 3) only the low value SLST group can be considered abnormal when age-matched normative SLST data are taken into account for comparison; and 4) lower UPDRS-III motor performance, and the bradykinesia sub-score in particular, are only associated with the low SLST group. Conclusion These results lend further support that a low SLST time around 10 seconds marks a clinically important stage of disease progression with significant worsening of postural stability in PD. PMID:25584104

  3. Organization position statements and the stance of "studied neutrality" on euthanasia in palliative care.

    PubMed

    Johnstone, Megan-Jane

    2012-12-01

    In recent years, palliative care and related organizations have increasingly adopted a stance of "studied neutrality" on the question of whether euthanasia should be legalized as a bona fide medical regimen in palliative care contexts. This stance, however, has attracted criticism from both opponents and proponents of euthanasia. Pro-euthanasia activists see the stance as an official position of indecision that is fundamentally disrespectful of a patient's right to "choose death" when life has become unbearable. Some palliative care constituents, in turn, are opposed to the stance, contending that it reflects an attitude of "going soft" on euthanasia and as weakening the political resistance that has hitherto been successful in preventing euthanasia from becoming more widely legalized. In this article, attention is given to examining critically the notion and possible unintended consequences of adopting a stance of studied neutrality on euthanasia in palliative care. It is argued that although palliative care and related organizations have an obvious stake in the outcome of the euthanasia debate, it is neither unreasonable nor inconsistent for such organizations to be unwilling to take a definitive stance on the issue. It is further contended that, given the long-standing tenets of palliative care, palliative care organizations have both a right and a responsibility to defend the integrity of the principles and practice of palliative care and to resist demands for euthanasia to be positioned either as an integral part or logical extension of palliative care. PMID:22771130

  4. A quasi-passive compliant stance control Knee-Ankle-Foot Orthosis.

    PubMed

    Shamaei, Kamran; Napolitano, Paul C; Dollar, Aaron M

    2013-06-01

    In this paper, we present the design of a novel quasi-passive stance-control orthosis that implements a natural amount of knee compliance during the weight acceptance phase and potentially the entire stance phase of the gait, and allows for free motion during the rest of the gait. We explain that the unaffected knee behaves close to a linear torsional spring in stance and hypothesize that an assistive device that places a linear spring of appropriate stiffness in parallel with the knee can help restore the natural behavior of the joint in stance. We present the design of a friction-based latching mechanism and a control algorithm that engages the spring in parallel with the knee in stance and disengages it during the swing phase of gait, and explain how this module is implemented into a brace in order to create a novel class of compliant stance control orthosis. The device is quasi-passive in that a small actuator serves to lock and unlock the spring module, but the device otherwise requires no actuation and very little power, computation, and control to operate. PMID:24187288

  5. As Go the Feet … : On the Estimation of Attentional Focus from Stance

    PubMed Central

    Quek, Francis; Ehrich, Roger; Lockhart, Thurmon

    2010-01-01

    The estimation of the direction of visual attention is critical to a large number of interactive systems. This paper investigates the cross-modal relation of the position of one's feet (or standing stance) to the focus of gaze. The intuition is that while one CAN have a range of attentional foci from a particular stance, one may be MORE LIKELY to look in specific directions given an approach vector and stance. We posit that the cross-modal relationship is constrained by biomechanics and personal style. We define a stance vector that models the approach direction before stopping and the pose of a subject's feet. We present a study where the subjects' feet and approach vector are tracked. The subjects read aloud contents of note cards in 4 locations. The order of `visits' to the cards were randomized. Ten subjects read 40 lines of text each, yielding 400 stance vectors and gaze directions. We divided our data into 4 sets of 300 training and 100 test vectors and trained a neural net to estimate the gaze direction given the stance vector. Our results show that 31% our gaze orientation estimates were within 5°, 51% of our estimates were within 10°, and 60% were within 15°. Given the ability to track foot position, the procedure is minimally invasive. PMID:20830212

  6. Single stance stability and proprioceptive control in older adults living at home: gender and age differences.

    PubMed

    Riva, Dario; Mamo, Carlo; Fanì, Mara; Saccavino, Patrizia; Rocca, Flavio; Momenté, Manuel; Fratta, Marianna

    2013-01-01

    In developed countries, falls in older people represent a rising problem. As effective prevention should start before the risk becomes evident, an early predictor is needed. Single stance instability would appear as a major risk factor. Aims of the study were to describe single stance stability, its sensory components, and their correlation with age and gender. A random sample of 597 older adults (319 men, 278 women) living at home, aged 65-84, was studied. Stability tests were performed with an electronic postural station. The single stance test showed the impairment of single stance stability in older individuals (75-84?yrs). The significant decline of stability in the older subjects may be explained by the impairment of proprioceptive control together with the decrease in compensatory visual stabilization and emergency responses. Younger subjects (65-74?yrs) exhibited better, but still inadequate, proprioceptive control with compensatory visual stabilization. Gender differences appeared in older subjects: women were significantly less stable than men. The measurement of the sensory components of single stance stability could aid in the early detection of a decay in antigravity movements many years before the risk of falling becomes evident. Adequate proprioceptive control could mitigate the effects of all other risks of falling. PMID:23984068

  7. Motor strategies used by rats spinalized at birth to maintain stance in response to imposed perturbations.

    PubMed

    Giszter, Simon F; Davies, Michelle R; Graziani, Virginia

    2007-04-01

    Some rats spinalized P1/P2 achieve autonomous weight-supported locomotion and quiet stance as adults. We used force platforms and robot-applied perturbations to test such spinalized rats (n = 6) that exhibited both weight-supporting locomotion and stance, and also normal rats (n = 8). Ground reaction forces in individual limbs and the animals' center of pressure were examined. In normal rats, both forelimbs and hindlimbs participated actively to control horizontal components of ground reaction forces. Rostral perturbations increased forelimb ground reaction forces and caudal perturbations increased hindlimb ground reaction forces. Operate rats carried 60% body weight on the forelimbs and had a more rostral center of pressure placement. The pattern in normal rats was to carry significantly more weight on the hindlimbs in quiet stance (roughly 60%). The strategy of operate rats to compensate for perturbations was entirely in forelimbs; as a result, the hindlimbs were largely isolated from the perturbation. Stiffness magnitude of the whole body was measured: its magnitude was hourglass shaped, with the principal axis oriented rostrocaudally. Operate rats were significantly less stiff--only 60-75% of normal rats' stiffness. The injured rats adopt a stance strategy that isolates the hindlimbs from perturbation and may thus prevent hindlimb loadings. Such loadings could initiate reflex stepping, which we observed. This might activate lumbar pattern generators used in their locomotion. Adult spinalized rats never achieve independent hindlimb weight-supported stance. The stance strategy of the P1 spinalized rats differed strongly from the behavior of intact rats and may be difficult for rats spinalized as adults to master. PMID:17287444

  8. Movement strategies and sensory reweighting in tandem stance: differences between trained tightrope walkers and untrained subjects.

    PubMed

    Honegger, F; Tielkens, R J M; Allum, J H J

    2013-12-19

    Does skill with a difficult task, such as tightrope walking, lead to improved balance through altered movement strategies or through altered weighting of sensory inputs? We approached this question by comparing tandem stance (TS) data between seven tightrope walkers and 12 untrained control subjects collected under different sensory conditions. All subjects performed four TS tasks with eyes open or closed, on a normal firm or foam surface (EON, ECN, EOF, ECF); tightrope walkers were also tested on a tightrope (EOR). Head, upper trunk and pelvis angular velocities were measured with gyroscopes in pitch and roll. Power spectral densities (PSDs) ratios, and transfer function gains (TFG) between these body segments were calculated. Center of mass (CoM) excursions and its virtual time to contact a virtual base of support boundary (VTVBS) were also estimated. Gain nonlinearities, in the form of decreased trunk to head and trunk to pelvis PSD ratios and TFGs, were present with increasing sensory task difficulty for both groups. PSD ratios and TFGs were less in trained subjects, though, in absolute terms, trained subjects moved their head, trunk, pelvis and CoM faster than controls, and had decreased VTVBS. Head roll amplitudes were unchanged with task or training, except above 3Hz. CoM amplitude deviations were not less for trained subjects. For the trained subjects, EOR measures were similar to those of ECF. Training standing on a tightrope induces a velocity modification of the same TS movement strategy used by untrained controls. More time is spent exploring the limits of the base of support with an increased use of fast trunk movements to control balance. Our evidence indicates an increased reliance on neck and pelvis proprioceptive inputs. The similarity of TS on foam to that on the tightrope suggests that the foam tasks are useful for effective training of tightrope walking. PMID:24090964

  9. Leaning-Based Travel Interfaces Revisited: Frontal versus Sidewise Stances for Flying in 3D Virtual Spaces

    E-print Network

    Lindeman, Robert W.

    revisit the design of leaning-based travel interfaces and propose a design space to categorize existing-centered design. Keywords Leaning-based travel interface; Stance; Navigation; 3D virtual spaces. 1. INTRODUCTIONLeaning-Based Travel Interfaces Revisited: Frontal versus Sidewise Stances for Flying in 3D Virtual

  10. Student Attachment Stances, Instructor Immediacy, and Student-Instructor Relationships as Predictors of Achievement Expectancies in College Students

    ERIC Educational Resources Information Center

    Creasey, Gary; Jarvis, Patricia; Gadke, Daniel

    2009-01-01

    In the present research, associations between student attachment stances, verbal and nonverbal instructor immediacy, student-instructor relationships, and student achievement orientations were specified. It was predicted that positive student-instructor relationships would mediate associations between student attachment stances, instructor…

  11. The effect of stance control orthoses on gait characteristics and energy expenditure in knee-ankle-foot orthosis users.

    PubMed

    Davis, Priya Chantal; Bach, Timothy Michael; Pereira, Darren Mark

    2010-06-01

    Stance Control knee-ankle foot orthoses (SCO) differ from their traditional locked knee counterparts by allowing free knee flexion during swing while providing stability during stance. It is widely accepted that free knee flexion during swing normalizes gait and therefore improves walking speed and reduces the energy requirements of walking. Limited research has been carried out to evaluate the benefits of SCOs when compared to locked knee-ankle foot orthoses (KAFOs). The purpose of this study was to evaluate the effectiveness of SCOs used for patients with lower limb pathology. Energy expenditure and walking velocity were measured in 10 subjects using an orthosis incorporating a Horton Stance Control knee joint. A GAITRite walkway was used to measure temporospatial gait characteristics. A Cosmed K4b2 portable metabolic system was used to measure energy expenditure and heart rate during walking. Two conditions were tested: Walking with stance control active (stance control) and walking with the knee joint locked. Ten subjects completed the GAITRite testing; nine subjects completed the Cosmed testing. Walking velocity was significantly increased in the stance control condition (p < 0.001). There was no difference in the energy cost of walking (p = 0.515) or physiological cost index (PCI) (p = 0.093) between conditions. This study supports previous evidence that stance control knee-ankle foot orthoses increase walking velocity compared to locked knee devices. Contrary to expectation, the stance control condition did not decrease energy expenditure during walking. PMID:20470059

  12. Cognitive Space 1 The Strong Cognitive Stance as a Conceptual Basis for the Role of Information in

    E-print Network

    Newby, Gregory B.

    Cognitive Space 1 The Strong Cognitive Stance as a Conceptual Basis for the Role of Information@ils.unc.edu Abstract This paper analyzes different approaches that have been taken to describe and utilize cognitive space for use with information systems. A "strong cognitive stance" on the role of information

  13. Ethical Considerations for Psychologists Taking a Public Stance on Controversial Issues: The Balance Between Personal and Professional Life

    PubMed Central

    Haeny, Angela M.

    2014-01-01

    Previous literature has documented the general issues psychologists often face while balancing their personal and professional lives. The struggle stems from attempting to satisfy the need to maintain a life outside of work while having the professional obligation to follow the American Psychological Association’s (APA’s) Ethical Principles of Psychologists and Code of Conduct (Ethics Code) to prevent their personal lives from interfering with their professional roles and relationships. The present paper analyzes the subject of psychologists taking a public position on controversial public issues. Although the APA Ethics Code does not restrict how psychologists conduct themselves during their personal time, taking a public stance on a controversial issue could potentially strain professional relationships and inadvertently reflect negatively on the profession. The present paper examines ethical issues that a) should be taken into account before psychologists take a public position on a controversial issue, and b) are in conflict with APA’s Ethics Code or current research. PMID:25342876

  14. Ethical Considerations for Psychologists Taking a Public Stance on Controversial Issues: The Balance Between Personal and Professional Life.

    PubMed

    Haeny, Angela M

    2014-07-01

    Previous literature has documented the general issues psychologists often face while balancing their personal and professional lives. The struggle stems from attempting to satisfy the need to maintain a life outside of work while having the professional obligation to follow the American Psychological Association's (APA's) Ethical Principles of Psychologists and Code of Conduct (Ethics Code) to prevent their personal lives from interfering with their professional roles and relationships. The present paper analyzes the subject of psychologists taking a public position on controversial public issues. Although the APA Ethics Code does not restrict how psychologists conduct themselves during their personal time, taking a public stance on a controversial issue could potentially strain professional relationships and inadvertently reflect negatively on the profession. The present paper examines ethical issues that a) should be taken into account before psychologists take a public position on a controversial issue, and b) are in conflict with APA's Ethics Code or current research. PMID:25342876

  15. Fixed patterns of rapid postural responses among leg muscles during stance

    Microsoft Academic Search

    L. M. Nashner

    1977-01-01

    The aim of this study has been to present firmer evidence that during stance functionally related postural muscles in the legs are activated according to fixed patterns. The importance of fixed patterns of activation for stabilization, balance, and movement control has received considerable theoretical and experimental attention. With regard to postural adjustment in humans, however, evidence for fixed activation patterns

  16. Are stance ankle plantar flexor muscles necessary to generate propulsive force during human gait initiation?

    Microsoft Academic Search

    V. Michel

    2002-01-01

    The study examined whether the generation of the forward propulsive force (PF) during gait initiation resulted mainly from the electromyogram activity of stance ankle plantar flexor muscles (APF) which ‘push’ on the ground as is generally claimed in the literature. Six unilateral above-knee amputees performed a specific gait initiation protocol, i.e. they were asked to walk as fast as possible

  17. Muscle contributions to support and progression during single-limb stance in crouch gait.

    PubMed

    Steele, Katherine M; Seth, Ajay; Hicks, Jennifer L; Schwartz, Michael S; Delp, Scott L

    2010-08-10

    Pathological movement patterns like crouch gait are characterized by abnormal kinematics and muscle activations that alter how muscles support the body weight during walking. Individual muscles are often the target of interventions to improve crouch gait, yet the roles of individual muscles during crouch gait remain unknown. The goal of this study was to examine how muscles contribute to mass center accelerations and joint angular accelerations during single-limb stance in crouch gait, and compare these contributions to unimpaired gait. Subject-specific dynamic simulations were created for ten children who walked in a mild crouch gait and had no previous surgeries. The simulations were analyzed to determine the acceleration of the mass center and angular accelerations of the hip, knee, and ankle generated by individual muscles. The results of this analysis indicate that children walking in crouch gait have less passive skeletal support of body weight and utilize substantially higher muscle forces to walk than unimpaired individuals. Crouch gait relies on the same muscles as unimpaired gait to accelerate the mass center upward, including the soleus, vasti, gastrocnemius, gluteus medius, rectus femoris, and gluteus maximus. However, during crouch gait, these muscles are active throughout single-limb stance, in contrast to the modulation of muscle forces seen during single-limb stance in an unimpaired gait. Subjects walking in crouch gait rely more on proximal muscles, including the gluteus medius and hamstrings, to accelerate the mass center forward during single-limb stance than subjects with an unimpaired gait. PMID:20493489

  18. Turkish Language Teachers' Stance Taking Movements in the Discourse on Globalization and Language

    ERIC Educational Resources Information Center

    Coskun, Ibrahim

    2013-01-01

    This study investigates how Turkish teachers take and give stances in the discourse on globalization and language by using linguistic resources. According to the findings obtained through the discourse analysis of the corpus that consisted of 36 h of recording of the discussion among 4 teachers with 5 to 10 years of teaching experience, the…

  19. Importance of Body Sway Velocity Information in Controlling Ankle Extensor Activities during Quiet Stance

    E-print Network

    Popovic, Milos R.

    to measure muscle activity in the right soleus muscle, the medial gastrocnemius mus- cle and the lateral quiet stance, and continuously modulates ankle extensor muscle activity to compensate for the change gastrocnemius muscle. The simulations were performed using an inverted pendulum model that described

  20. Pedunculopontine ucleus Area Oscillations during Stance, Stepping and Freezing in Parkinson's Disease

    E-print Network

    Paris-Sud XI, Université de

    , and stance in seven Parkinson's disease patients who received bilateral PPNa implantation for disabling of the PPNa in the regulation of gait and suggest that, in Parkinson disease, gait difficulties could in Parkinson's Disease. PLoS ONE 8(12): e83919. doi:10.1371/journal.pone.0083919 Editor: Mathias Toft, Oslo

  1. Argument or Evidence? Disciplinary Variation in the Use of the Noun "that" Pattern in Stance Construction

    ERIC Educational Resources Information Center

    Charles, Maggie

    2007-01-01

    This paper uses a corpus approach to investigate disciplinary variation in the construction of stance using nouns which are followed by "that" and a complement clause, "e.g. the argument that the Justices exhibit strategic behaviour..." Two corpora of theses written in English are examined: approximately 190,000 words in politics/international…

  2. Stance and Engagement in Pure Mathematics Research Articles: Linking Discourse Features to Disciplinary Practices

    ERIC Educational Resources Information Center

    McGrath, Lisa; Kuteeva, Maria

    2012-01-01

    Recent ESP research into academic writing has shown how writers convey their stance and interact with readers across different disciplines. However, little research has been carried out into the disciplinary writing practices of the pure mathematics academic community from an ESP genre analysis perspective. This study begins to address this gap by…

  3. Embodied Discourse: Using Tableau to Explore Preservice Teachers' Reflections and Activist Stances

    ERIC Educational Resources Information Center

    Branscombe, Margaret; Schneider, Jenifer Jasinski

    2013-01-01

    In the context of an arts-integration course in an elementary education program, preservice teachers used tableaux (i.e. frozen scenes) to portray field experience moments in two ways: (1) as remembered events, and (2) as projected possibilities. Using video and photographs of the tableaux, we traced the students' enactment of activist stances and…

  4. Muscle activation characteristics of stance balance control in children with spastic cerebral palsy

    Microsoft Academic Search

    P. A Burtner; C Qualls; M. H Woollacott

    1998-01-01

    Two studies were conducted to investigate muscle recruitment of children with spastic cerebral palsy in response to unexpected perturbation of balance in stance. The aim of the studies was to investigate neural and non-neural mechanical contributions to muscle responses differences these children display when maintaining balance. In the first study, muscle responses of children with spastic diplegia were compared to

  5. Elementary Students' Roles and Epistemic Stances during Document-Based History Lessons

    ERIC Educational Resources Information Center

    Nokes, Jeffery D.

    2014-01-01

    This article reports on a study that repositioned elementary students in new roles as active, critical participants in historical inquiry--roles that required a more mature epistemic stance. It reports 5th-grade students' responses to instructional methods intended to help them understand the nature of historical knowledge, appreciate the…

  6. Frontal plane knee angle affects dynamic postural control strategy during unilateral stance

    Microsoft Academic Search

    JOHN NYLAND; STEVE SMITH; KURT BEICKMAN; THOMAS ARMSEY; DAVID N. M. CABORN

    2002-01-01

    NYLAND, J., S. SMITH, K. BEICKMAN, T. ARMSEY, and D. N. M. CABORN. Frontal plane knee angle affects dynamic postural control strategy during unilateral stance. Med. Sci. Sports Exerc., Vol. 34, No. 7, pp. 1150 -1157, 2002. Purpose: Center of plantar pressure (COPP) location moves toward the forefoot as ankle plantar flexor muscles attempt to maintain postural control during single

  7. Divergent Effects of Cognitive Load on Quiet Stance and Task-Linked Postural Coordination

    ERIC Educational Resources Information Center

    Mitra, Suvobrata; Knight, Alec; Munn, Alexandra

    2013-01-01

    Performing a cognitive task while maintaining upright stance can lead to increased or reduced body sway depending on tasks and experimental conditions. Because greater sway is commonly taken to indicate loosened postural control, and vice versa, the precise impact of cognitive load on postural stability has remained unclear. In much of the large…

  8. Problematising Researcher-Respondent Relations through an Exploration of Communicative Stance

    ERIC Educational Resources Information Center

    Lefstein, Adam

    2010-01-01

    To what extent and in what ways should researchers share their views with research participants during ethnographic fieldwork? This article discusses the author's experience of adopting different communicative stances with respondents in the context of an ethnographic study of the enactment of the English National Literacy Strategy in a "failing"…

  9. Dominant side in single-leg stance stability during floor oscillations at various frequencies

    PubMed Central

    2014-01-01

    Background We investigated lateral dominance in the postural stability of single-leg stance with anteroposterior floor oscillations at various frequencies. Methods Thirty adults maintained a single-leg stance on a force platform for 20 seconds per trial. Trials were performed with no oscillation (static condition) and with anteroposterior floor oscillations (2.5-cm amplitude) at six frequencies: 0.25, 0.5, 0.75, 1.0, 1.25 and 1.5 Hz (dynamic condition). A set of three trials was performed on each leg in each oscillation frequency in random order. The mean speed of the center of pressure in the anteroposterior direction (CoPap) was calculated as an index of postural stability, and frequency analysis of CoPap sway was performed. Footedness for carrying out mobilizing activities was assessed with a questionnaire. Results CoPap speed exponentially increased as oscillation frequency increased in both legs. The frequency analysis of CoPap showed a peak <0.3 Hz at no oscillation. The frequency components at 0.25-Hz oscillation included common components with no oscillation and those at 1.5-Hz oscillation showed the maximum amplitude among all conditions. Postural stability showed no significant difference between left- and right-leg stance at no oscillation and oscillations ?1.25 Hz, but at 1.5-Hz oscillation was significantly higher in the right-leg stance than in the left-leg stance. For the lateral dominance of postural stability at individual levels, the lateral difference in postural stability at no oscillation was positively correlated with that at 0.25-Hz oscillation (r?=?0.51) and negatively correlated with that at 1.5-Hz oscillation (r?=?-0.53). For 70% of subjects, the dominant side of postural stability was different at no oscillation and 1.5-Hz oscillation. In the subjects with left- or right-side dominance at no oscillation, 94% or 38% changed their dominant side at 1.5-Hz oscillation, with a significant difference between these percentages. In the 1.5-Hz oscillation, 73% of subjects had concordance between the dominant side of postural stability and that of mobilizing footedness. Conclusion In static conditions, there was no lateral dominance of stability during single-leg stance. At 1.5-Hz oscillation, the highest frequency, right-side dominance of postural stability was recognized. Functional role in supporting leg may be divided between left and right legs according to the change of balance condition from static to dynamic. PMID:25127541

  10. Speaking "Common Sense" about the Soviet Threat: Reagan's Rhetorical Stance.

    ERIC Educational Resources Information Center

    Ivie, Robert L.

    Although for the 15 years preceding his election as President of the United States Ronald Reagan muted his anti-Soviet rhetoric in order to achieve political power, since his election he has returned to anti-Sovietism in an effort to redirect American foreign policy against the Soviets. At the same time, however, he employs a rhetorical strategy…

  11. Constructing language normativity through the animation of stance in spanish-language medical consultations.

    PubMed

    Vickers, Caroline H; Deckert, Sharon K; Goble, Ryan

    2014-01-01

    The purpose of this study is to examine the construction of language normativity as medical providers interact with patients and animate stance within Spanish-language medical consultations. The context of the study is a clinic in which providers use Spanish to communicate with monolingual Spanish-speaking patients. This clinic is in the United States, an English-speaking macro-societal context. Findings indicate that providers who are second-language users of Spanish animate stance and interact with patients in ways such that English is constructed as normative and Spanish as marked. Implications include the need to consider how the construction of language normativity within medical consultations affects health outcomes. PMID:24156518

  12. Stance and strategy: post-structural perspective and post-colonial engagement to develop nursing knowledge.

    PubMed

    Sochan, Anne M

    2011-07-01

    How should nursing knowledge advance? This exploration contextualizes its evolution past and present. In addressing how it evolved in the past, a probable historical evolution of its development draws on the perspectives of Frank & Gills's World System Theory, Kuhn's treatise on Scientific Revolutions, and Foucault's notions of Discontinuities in scientific knowledge development. By describing plausible scenarios of how nursing knowledge evolved, I create a case for why nursing knowledge developers should adopt a post-structural stance in prioritizing their research agenda(s). Further, by adopting a post-structural stance, I create a case on how nurses can advance their disciplinary knowledge using an engaging post-colonial strategy. Given an interrupted history caused by influence(s) constraining nursing's knowledge development by power structures external, and internal, to nursing, knowledge development can evolve in the future by drawing on post-structural interpretation, and post-colonial strategy. The post-structural writings of Deleuze & Guattari's understanding of 'Nomadology' as a subtle means to resist being constrained by existing knowledge development structures, might be a useful stance to understanding the urgency of why nursing knowledge should advance addressing the structural influences on its development. Furthermore, Bhabha's post-colonial elucidation of 'Hybridity' as an equally discreet means to change the culture of those constraining structures is an appropriate strategy to enact how nursing knowledge developers can engage with existing power structures, and simultaneously influence that engagement. Taken together, 'post-structural stance' and 'post-colonial strategy' can refocus nursing scholarship to learn from its past, in order to develop relevant disciplinary knowledge in its future. PMID:21668617

  13. Light touch modulates balance recovery following perturbation: from fast response to stance restabilization.

    PubMed

    Martinelli, Alessandra Rezende; Coelho, Daniel Boari; Magalhães, Fernando Henrique; Kohn, André Fabio; Teixeira, Luis Augusto

    2015-05-01

    Light fingertip touch of a static bar generates extra somatosensory information used by the postural control system to reduce body sway. While the effect of light touch has been studied in quiet stance, less attention has been given to its potential benefit for reactive postural responses. In the present study, we tested the effect of light fingertip touch of a stable surface on recovery of postural stability from a mechanical perturbation. Participants stood upright on a force plate touching a static rigid bar while being pulled backward by a load. Unpredictable release of the load induced fast anterior body sway, requiring a reactive response to recover balance. Effect of light touch on postural responses was assessed as a function of vision and malleability of the support surface, analyzing different epochs ranging from the pre-perturbation period to recovery of a relatively stable quiet stance. Results showed that light touch induced lower magnitude of muscular activation in all epochs. Center of pressure (CoP) displacement/sway was affected by interaction of light touch with manipulation of the other sensory information. For the periods associated with quiet stance, light touch led to decreased CoP sway in the malleable surface in the pre-perturbation epoch, and in the condition combining no vision and malleable surface in the balance restabilization and follow-up quiet stance epochs. For the fast reactive response epoch, light touch induced smaller amplitude of CoP displacement across conditions, and lower CoP maximum velocity in the condition combining no vision and rigid surface. These results showed that light touch modulates postural responses in all epochs associated with an unanticipated mechanical perturbation, with a more noticeable effect in conditions manipulating sensory information relevant for balance control. PMID:25644655

  14. Design, Construction and Evaluation of an Electromechanical Stance-Control Knee-Ankle-Foot Orthosis

    Microsoft Academic Search

    Terris Yakimovich; Jonathan Kofman; Edward Lemaire

    2005-01-01

    A new electromechanical stance-control knee-ankle-foot orthosis (SCKAFO) was designed to provide improved gait for people with knee-extensor weakness. This SCKAFO inhibits knee flexion at any knee angle while allowing knee extension during weight bearing. During swing or other non-weight bearing activities, the SCKAFO allows free knee motion. A prototype joint was mechanically tested to determine the moment at failure, loading

  15. Design, Construction and Evaluation of an Electromechanical Stance-Control Knee-Ankle-Foot Orthosis

    Microsoft Academic Search

    Terris Yakimovich; Jonathan Kofman; Edward Lemaire

    2005-01-01

    A new electromechanical Stance-Control Knee-Ankle-Foot Orthosis (SCKAFO) was designed to provide improved gait for people with knee-extensor weakness. This SCKAFO inhibits knee flexion at any knee angle while allowing knee extension during weight bearing. During swing or other non-weight bearing activities, the SCKAFO allows free knee motion. A prototype joint was mechanically tested to determine the moment at failure, loading

  16. Design and Evaluation of a Stance-Control Knee-Ankle-Foot Orthosis Knee Joint

    Microsoft Academic Search

    Terris Yakimovich; Jonathan Kofman; Edward D. Lemaire

    2006-01-01

    Conventional knee-ankle-foot orthoses (KAFOs) are prescribed for people with knee-extensor muscle weakness. However, the orthoses lock the knee in full extension and, therefore, do not permit a natural gait pattern. A new electromechanical stance-control knee-ankle-foot orthosis (SCKAFO) knee joint that employs a novel friction-based belt-clamping mechanism was designed to enable a more natural gait. The SCKAFO knee joint allows free

  17. From relational ontology to transformative activist stance on development and learning: expanding Vygotsky's (CHAT) project

    NASA Astrophysics Data System (ADS)

    Stetsenko, Anna

    2008-07-01

    This paper offers steps towards overcoming current fragmentation within sociocultural approaches by expansively reconstructing a broad dialectical view on human development and learning (drawing on Vygotsky's project) underwritten by ideology of social justice. The common foundation for sociocultural approaches is developed by dialectically supplanting relational ontology with the notion that collaborative purposeful transformation of the world is the core of human nature and the principled grounding for learning and development. An activist transformative stance suggests that people come to know themselves and their world as well as ultimately come to be human in and through (not in addition to) the processes of collaboratively transforming the world in view of their goals. This means that all human activities (including psychological processes and the self) are instantiations of contributions to collaborative transformative practices that are contingent on both the past and the vision for the future and therefore are profoundly imbued with ideology, ethics, and values. And because acting, being, and knowing are seen from a transformative activist stance as all rooted in, derivative of, and instrumental within a collaborative historical becoming, this stance cuts across and bridges the gaps (a) between individual and social and (b) among ontological, epistemological, and moral-ethical (ideological) dimensions of activity.

  18. Unilateral Stance Strategies of Athletes With ACL Deficiency

    PubMed Central

    Di Stasi, Stephanie L.; Hartigan, Erin H.; Snyder-Mackler, Lynn

    2013-01-01

    Aberrant movement strategies are characteristic of ACL-deficient athletes with recurrent knee instability (non-copers), and may instigate premature or accelerate joint degradation. Biomechanical evaluation of kinematic changes over time may elucidate noncopers’ responses to neuromuscular intervention and ACL reconstruction (ACLR). Forty noncopers were randomized into a perturbation group or a strength training only group. We evaluated the effects of perturbation training, and then gender on knee angle and tibial position during a unilateral standing task before and after ACLR. No statistically significant interactions were found. Before surgery, the strength training only group demonstrated knee angle asymmetry, but 6 months after ACLR, both groups presented with similar knee flexion between limbs. Aberrant and asymmetrical tibial position was found only in females following injury and ACLR. Neither treatment group showed distinct unilateral standing strategies following intervention; however, males and female noncopers appear to respond uniquely to physical therapy and surgery. PMID:22983931

  19. Exploratory behavior during stance persists with visual feedback.

    PubMed

    Murnaghan, C D; Horslen, B C; Inglis, J T; Carpenter, M G

    2011-11-10

    Recent evidence showing center of pressure (COP) displacements increase following an external stabilization of the center of mass (COM) supports the theory that postural sway may be exploratory and serve as a means of acquiring sensory information. The aim of the current study was to further test this theory and rule out potential confounding effects of sensory illusions or motor drift on prior observations. Participants stood as still as possible in an apparatus which allowed movements of the COM to be stabilized ("locked") without subject awareness, and they were provided real-time visual feedback of their COM or COP throughout the trial. If there was an influence of sensory illusions or motor drift, we hypothesized that the change in COP displacement with locking would be reduced when participants were provided visual confirmation of COM stabilization (COM feedback), or when they were aware of the position of the COP throughout the trial (COP feedback). Confirming our previous results, increases in COP displacement were observed when movements of the COM were stabilized. In addition, our results showed that increases in COP displacement could not be explained by the presence of sensory illusions or motor drift, since increases in COP were observed despite being provided convincing evidence that the COM had been stabilized, and when participants were aware of their COP position throughout the trial. These results provide further support for an exploratory role of postural sway. The theoretical basis of current clinical practices designed to deal with balance control deficits due to age or disease is typically based on the opinion that increases in sway are a consequence of a failing balance control system. Our results suggest that this may not be the case, and if sway is in fact exploratory, a serious re-evaluation of current clinical practices may be warranted. PMID:21867743

  20. Postoperative gait velocity and mean knee flexion in stance of ambulatory children with spastic diplegia four years or more after multilevel surgery.

    PubMed

    Gannotti, Mary E; Gorton, George E; Nahorniak, Maureen T; Masso, Peter D; Landry, Bradford; Lyman, Jeffrey; Sawicki, Rebecca; Hagedorn, Kristin; Ross, Ellen; Warner, Jennifer

    2007-06-01

    Factors associated with longer-term outcomes of multilevel orthopaedic surgery in ambulatory children with cerebral palsy using a multivariate approach were evaluated using a retrospective pretest-posttest design. The population included 20 ambulatory children with spastic diplegia who had undergone multilevel orthopaedic surgery with a minimum of 4-year interval between a preoperative and a postoperative gait assessment. Multiple regression analysis was used to identify factors associated with postoperative velocity and mean knee flexion in stance. Independent variables included in the regression models were velocity, mean knee flexion in stance, age at preoperative evaluation, Gross Motor Function Classification System level, use of ankle-foot orthoses, leg length, age-adjusted body mass index, number of surgical procedures, and range of motion of hip and knee. Children who demonstrated faster postoperative gait velocity 4 years or more after surgery were younger at the time of initial evaluation, had undergone fewer surgical procedures, had faster preoperative gait velocity, used ankle-foot orthoses postoperatively, and had increased hip extension range of motion postoperatively (R = 0.55). Children who demonstrated greater knee flexion in stance 4 years or more after surgery had undergone more surgical procedures, greater postoperative popliteal angle, and less knee extension range of motion (R = 0.73). This study demonstrates the usefulness of a multivariate approach toward understanding and predicting outcomes. The results of this study will provide clinicians and researchers more information about those factors associated with maintained improvements in the longer term and may be useful for treatment planning. PMID:17513969

  1. Non-Gaussian center-of-pressure velocity distribution during quiet stance

    NASA Astrophysics Data System (ADS)

    Santos, E. S. D.; Picoli, S.; Deprá, P. P.; Mendes, R. S.

    2015-02-01

    In the present study, we investigate patterns in the postural sway that characterize the static balance in human beings. To measure the postural sway, sixteen healthy young subjects performed quiet stance tasks providing the center-of-pressure (COP) trajectories. From these trajectories, we obtained the COP velocities. We verified that the velocity distributions exhibit non-normal behavior and can be approximated by generalized Gaussians with fat tails. We also discuss possible implications of modeling COP velocity by using generalized Fokker-Planck equations related to Tsallis statistics and Richardson anomalous diffusion.

  2. Lateral ankle sprain alters postural control in bipedal stance--part 1: restoration over the 30 days following the injury.

    PubMed

    Genthon, N; Bouvat, E; Banihachemi, J J; Bergeau, J; Abdellaoui, A; Rougier, P R

    2010-04-01

    The time evolution of the postural behavior of 23 lateral ankle sprain patients (degrees I and II) were evaluated 14 h and 10 and 30 days on average after their injury and compared with those of 30 age-matched healthy individuals. The patients were tested with separate measurements of the reaction forces under each limb to highlight the possible compensatory mechanisms between the sound and the injured legs. Their postural behavior in bipedal stance was characterised by a weight-bearing asymmetry with more weight on the sound leg and an asymmetry of the postural stabilisation mechanisms, which are limited and perturbed under the injured leg. Pain appears to be the main factor for explaining these postural asymmetries. Despite these asymmetries, the patients were nonetheless more unstable than the individuals constituting the group control. Ten days later, only the weight-bearing asymmetry was still observed whereas 30 days later, the postural behavior was totally normal once again. Lateral ankle sprain perturbs the contribution of the injured leg in postural stabilisation, inducing a larger involvement of the sound leg in the postural stability process. These characteristics are largely reduced 10 days after the injury. PMID:19422652

  3. Estimation of Quasi-Stiffness of the Human Knee in the Stance Phase of Walking

    PubMed Central

    Shamaei, Kamran; Sawicki, Gregory S.; Dollar, Aaron M.

    2013-01-01

    Biomechanical data characterizing the quasi-stiffness of lower-limb joints during human locomotion is limited. Understanding joint stiffness is critical for evaluating gait function and designing devices such as prostheses and orthoses intended to emulate biological properties of human legs. The knee joint moment-angle relationship is approximately linear in the flexion and extension stages of stance, exhibiting nearly constant stiffnesses, known as the quasi-stiffnesses of each stage. Using a generalized inverse dynamics analysis approach, we identify the key independent variables needed to predict knee quasi-stiffness during walking, including gait speed, knee excursion, and subject height and weight. Then, based on the identified key variables, we used experimental walking data for 136 conditions (speeds of 0.75–2.63 m/s) across 14 subjects to obtain best fit linear regressions for a set of general models, which were further simplified for the optimal gait speed. We found R2 > 86% for the most general models of knee quasi-stiffnesses for the flexion and extension stages of stance. With only subject height and weight, we could predict knee quasi-stiffness for preferred walking speed with average error of 9% with only one outlier. These results provide a useful framework and foundation for selecting subject-specific stiffness for prosthetic and exoskeletal devices designed to emulate biological knee function during walking. PMID:23533662

  4. Use of physical therapy in a dog with bilateral severe plantigrade stance.

    PubMed

    Ree, Jennifer; Hayashi, Kei; Woelz, Jacqueline; Kim, Sun Young

    2015-01-01

    A 3.5 yr old spayed female Staffordshire terrier weighing 25.5 kg was presented with a 7 wk history of bilateral plantigrade stance in the pelvic limbs directly following an ovariohysterectomy procedure. Upon presentation, the dog had bilateral atrophy of the distal pelvic limb muscles, enlarged popliteal lymph nodes, and ulcerative wounds on the dorsa of her rear paws. Orthopedic examination revealed intact calcaneal tendons bilaterally and neurologic examination localized the lesion to the distal sciatic nerve. A diagnosis of compressive and stretch neuropathy was made affecting the distal sciatic nerve branches. Physical therapy modalities included neuromuscular electrical stimulation, ultrasound, and low-level laser therapy. Other therapeutic modalities included the use of orthotics and progressive wound care. The dog had increased muscle mass, return of segmental reflexes, return of nociception, and the ability to walk on pelvic limbs with higher carriage of the hock 15 mo following presentation. The use of custom orthotics greatly increased the quality of life and other physical therapy modalities may have improved the prognosis in this dog with severe bilateral plantigrade stance due to neuropathy. PMID:25415214

  5. Estimation of quasi-stiffness of the human knee in the stance phase of walking.

    PubMed

    Shamaei, Kamran; Sawicki, Gregory S; Dollar, Aaron M

    2013-01-01

    Biomechanical data characterizing the quasi-stiffness of lower-limb joints during human locomotion is limited. Understanding joint stiffness is critical for evaluating gait function and designing devices such as prostheses and orthoses intended to emulate biological properties of human legs. The knee joint moment-angle relationship is approximately linear in the flexion and extension stages of stance, exhibiting nearly constant stiffnesses, known as the quasi-stiffnesses of each stage. Using a generalized inverse dynamics analysis approach, we identify the key independent variables needed to predict knee quasi-stiffness during walking, including gait speed, knee excursion, and subject height and weight. Then, based on the identified key variables, we used experimental walking data for 136 conditions (speeds of 0.75-2.63 m/s) across 14 subjects to obtain best fit linear regressions for a set of general models, which were further simplified for the optimal gait speed. We found R(2) > 86% for the most general models of knee quasi-stiffnesses for the flexion and extension stages of stance. With only subject height and weight, we could predict knee quasi-stiffness for preferred walking speed with average error of 9% with only one outlier. These results provide a useful framework and foundation for selecting subject-specific stiffness for prosthetic and exoskeletal devices designed to emulate biological knee function during walking. PMID:23533662

  6. Movement coupling at the ankle during the stance phase of running.

    PubMed

    Stacoff, A; Nigg, B M; Reinschmidt, C; van den Bogert, A J; Lundberg, A; Stüssi, E; Denoth, J

    2000-03-01

    The purpose of this study was to quantify movement coupling at the ankle during the stance phase of running using bone-mounted markers. Intracortical bone pins with reflective marker triads were inserted under standard local anaesthesia into the calcaneus and the tibia of five healthy male subjects. The three-dimensional rotations were determined using a joint coordinate system approach. Movement coupling was observed in all test subjects and occurred in phases with considerable individual differences. Between the shoe and the calcaneus coupling increased after midstance which suggested that the test shoes provided more coupling for inversion than for eversion. Movement coupling between calcaneus and tibia was higher in the first phase (from heel strike to midstance) compared with the second phase (from midstance to take-off). This finding is in contrast to previous in-vitro studies but may be explained by the higher vertical loads of the present in-vivo study. Thus, movement coupling measured at the bone level changed throughout the stance phase of running and was found to be far more complex than a simple mitered joint or universal joint model. PMID:10739155

  7. The amount of rearfoot motion used during the stance phase of walking.

    PubMed

    Youberg, Linda Dowdy; Cornwall, Mark W; McPoil, Thomas G; Hannon, Patrick R

    2005-01-01

    The purpose of this study was to determine the proportion of available passive frontal plane rearfoot motion that is used during the stance phase of walking. Data were collected from 40 healthy, asymptomatic volunteer subjects (20 men and 20 women) aged 23 to 44 years. Passive inversion and eversion motion was measured in a non-weightbearing position by manually moving the calcaneus. Dynamic rearfoot motion was referenced to a vertical calcaneus and tibia and was measured using a three-dimensional electromagnetic motion-analysis system. The results indicated that individuals used 68.1% of their available passive eversion range of motion and 13.2% of their available passive inversion range of motion during walking. The clinical implication of individuals' regularly operating at or near the end point of their available rearfoot eversion range of motion is discussed. PMID:16037554

  8. Assessment of AK (Above Knee) Prosthesis with Different Ankle Assembly Using GRF Pattern in Stance Phase

    NASA Astrophysics Data System (ADS)

    Kim, Sung-Min; Kim, Sung-Jae; Bae, Ha-Suk

    In this study, ground reaction force (GRF), absolute symmetry index (ASI) and coefficient of variation (CV) of fixed, single-axis and multi-axis prosthetic ankle assemblies were investigated by biomechanical evaluation of above knee amputees. In the experiments, 37 normal male volunteers, two male and two female Above Knee (AK) amputees GRF data were tested with fixed, single-axis and multi-axis prosthetic ankle assembly. A gait analysis was carried out to derive the ratio of GRF to weight as the percentage of total stance phase for ten points. The results showed that fixed-axis ankle assembly was superior to other two ankle assemblies for forwarding and braking forces. Multi-axis ankle was relatively superior to other two ankle assemblies for gait balancing and movement of the mass center. Single-axis ankle was relatively superior to the other two ankle assemblies for CV and ASI of GRF.

  9. Knowing When to Doubt: Developing a Critical Stance When Learning From Others

    PubMed Central

    Mills, Candice M.

    2013-01-01

    Children may be biased towards accepting information as true, but the fact remains that children are exposed to misinformation from many sources, and mastering the intricacies of doubt is necessary. The current article examines this issue, focusing on understanding developmental changes and consistencies in children’s ability to take a critical stance towards information. Research is reviewed on children’s ability to detect ignorance, inaccuracy, incompetence, deception, and distortion. Particular emphasis is placed on what this research indicates about how children are reasoning about when to trust and when to doubt. The remainder of the article proposes a framework to evaluate preexisting research and encourage further research, closing with a discussion of several other overarching questions that need to be considered in order to develop a model to explain developmental, individual, and situational differences in children’s ability to evaluate information. PMID:22889395

  10. "How Do I Do It if I Don't Like Writing?": Adolescents' Stances toward Writing across Disciplines

    ERIC Educational Resources Information Center

    Jeffery, Jill V.; Wilcox, Kristen

    2014-01-01

    This research embedded in the National Study of Writing Instruction examines higher- and lower-achieving adolescents' stances toward content-area writing through a qualitative discourse analysis of interviews with 40 students in California, Kentucky, New York, and Texas secondary schools. The study asked: (1) How do students' stances

  11. Postflight Quiet Stance Stability of Astronauts Following Recovery From a Simulated Fall

    NASA Technical Reports Server (NTRS)

    Reschke, M. F.; Kofman, I. S.; Fisher, E. A.; Cerisano, J. M.; Lawrence, E. L.; Peters, B. T.; Harm, D. L.; Kulecz, W.; Mulavara, A. P.; Fiedler, M. J.; Bloomberg, J. J.

    2010-01-01

    INTRODUCTION: Astronauts returning from space flight universally present with postural ataxia. Throughout the Space Shuttle Program, measurement of ataxia has concentrated on sway in the anterior-posterior plane. Implementation of an interdisciplinary pre- and postflight study (Functional Task Test, FTT) designed to evaluate both astronaut postflight functional performance and related physiological changes has allowed the investigation of postural instability by characterizing dynamic stabilographic sway patterns. METHODS: Six astronauts from short-duration (Shuttle) and three from long-duration (ISS) flights were required to recover from a simulated fall. Subjects with eyes open, wearing running shoes lay prone on the floor for 2 minutes and then quickly stood up, maintained a quiet stance for 3 minutes, arms relaxed along the side of the body, and feet comfortably placed on the force plate. Crewmembers were tested twice before flight, on landing day (Shuttle only), and 1, 6, and 30 days after flight. Anterior-posterior (AP) and medial-lateral (ML) center-of-pressure (COP) coordinates were calculated from the ground reaction forces collected at 500 Hz. The 3-minute quiet stance trial was broken into three 1-minute segments for stabilogram diffusion analysis. A mean sway speed (rate of change of COP displacement) was also calculated as an additional postural stability parameter. RESULTS/CONCLUSION: While there was considerable variation, most of crewmembers tested exhibited increased stochastic activity evidenced by larger short-term COP diffusion coefficients postflight in both the AP and ML planes, suggesting significant changes in postural control mechanisms, particularly control of lower limb muscle function. As expected, postural instability of ISS astronauts on the first day postflight was similar to that of Shuttle crewmembers on landing day. Recoveries of stochastic activity and mean sway speed to baseline levels were typically observed by the 30th day postflight for both long-duration and short-duration crewmembers. Dynamic postural stability characteristics obtained in this low-impact study complement the data measured with computerized dynamic posturography.

  12. Feet distance and static postural balance: implication on the role of natural stance.

    PubMed

    Kim, Ji-Won; Kwon, Yuri; Jeon, Hyung-Min; Bang, Min-Jung; Jun, Jae-Hoon; Eom, Gwang-Moon; Lim, Do-Hyung

    2014-01-01

    The purpose of this study was to investigate 1) the effect of feet distance on static postural balance and 2) the location of natural feet distance and its possible role in the relationship of feet distance and postural balance. Static balance tests were performed on a force platform for 100 s with six different feet distances (0, 5, 10, 15, 20, 25 cm). Measures of postural balance included mean amplitude of horizontal ground reaction force (GRF) as well as the mean distance and velocity of the center of pressure (COP). All measures were discomposed into anterioposterior and mediolateral directions. ANOVA and post-hoc comparison were performed for all measures with feet distance as an independent factor. Also measured was the feet distance at the natural stance preferred by each subject. All measures significantly varied with feet distance (p<0.001). Mean distance of COP showed monotonic decrease with feet distance. Mean amplitude of horizontal GRF as well as mean velocity of COP showed U-shaped pattern (decrease followed by increase) with the minimum at the feet distance of 15 cm or 20 cm, near which the natural feet distance of 16.5 (SD 3.8) cm was located. COP is regarded to be an approximation of the center of mass (hence the resultant performance of postural control) in an inverted pendulum model with the horizontal GRF ignored. On the other hand, horizontal GRF is the direct cause of horizontal acceleration of a center of mass. The present result on horizontal GRF shows that the effort of postural control is minimized around the feet distance of natural standing and implies why the natural stance is preferred. PMID:25226972

  13. Coordinated, multi-joint, fatigue-resistant feline stance produced with intrafascicular hind limb nerve stimulation

    NASA Astrophysics Data System (ADS)

    Normann, R. A.; Dowden, B. R.; Frankel, M. A.; Wilder, A. M.; Hiatt, S. D.; Ledbetter, N. M.; Warren, D. A.; Clark, G. A.

    2012-04-01

    The production of graceful skeletal movements requires coordinated activation of multiple muscles that produce torques around multiple joints. The work described herein is focused on one such movement, stance, that requires coordinated activation of extensor muscles acting around the hip, knee and ankle joints. The forces evoked in these muscles by external stimulation all have a complex dependence on muscle length and shortening velocities, and some of these muscles are biarticular. In order to recreate sit-to-stand maneuvers in the anesthetized feline, we excited the hind limb musculature using intrafascicular multielectrode stimulation (IFMS) of the muscular branch of the sciatic nerve, the femoral nerve and the main branch of the sciatic nerve. Stimulation was achieved with either acutely or chronically implanted Utah Slanted Electrode Arrays (USEAs) via subsets of electrodes (1) that activated motor units in the extensor muscles of the hip, knee and ankle joints, (2) that were able to evoke large extension forces and (3) that manifested minimal coactivation of the targeted motor units. Three hind limb force-generation strategies were investigated, including sequential activation of independent motor units to increase force, and interleaved or simultaneous IFMS of three sets of six or more USEA electrodes that excited the hip, knee and ankle extensors. All force-generation strategies evoked stance, but the interleaved IFMS strategy also reduced muscle fatigue produced by repeated sit-to-stand maneuvers compared with fatigue produced by simultaneous activation of different motor neuron pools. These results demonstrate the use of interleaved IFMS as a means to recreate coordinated, fatigue-resistant multi-joint muscle forces in the unilateral hind limb. This muscle activation paradigm could provide a promising neuroprosthetic approach for the restoration of sit-to-stand transitions in individuals who are paralyzed by spinal cord injury, stroke or disease.

  14. Stochastic optimization for the calculation of the optimal critical curve from experimental data in a model of the process of regaining balance after perturbation from quiet stance

    NASA Astrophysics Data System (ADS)

    Zakynthinaki, M. S.; Stirling, J. R.; de Durana, A. López Díaz; Martínez, C. A. Cordente; Quintana, M. Sillero; Molinuevo, J. Sampedro

    2008-10-01

    We demonstrate the successful application of ALOPEX stochastic optimization to the problem of calculating the optimal critical curve in a dynamical systems model of the process of regaining balance after perturbation from quiet stance. Experimental data provide the time series of angles for which the subjects were able to regain balance after an initial perturbation. The optimal critical curve encloses all data points and has a minimum distance from the border points of the data set. We demonstrate the results of the optimization firstly using the traditional cost function of chi-square distance. We then successfully introduce a modified cost function that fits the model to the experimental data by taking into account the specific requirements of the model. By use of the proposed cost function, combined with the efficiency of our optimization method, an optimal critical curve is calculated even in the cases of very asymmetric data sets that lie within the capabilities of the existing model.

  15. Different activations of the soleus and gastrocnemii muscles in response to various types of stance perturbation in man

    Microsoft Academic Search

    A. Nardone; T. Corrà; M. Schieppati

    1990-01-01

    The soleus (Sol) and medial and lateral gastrocnemii (GM and GL) behave differently during various movements, but no attempt has been made to disclose any distinct activation of these muscles during perturbations of upright stance. Therefore the pattern of activation of the three triceps surae (TS) muscles and of the tibialis anterior (TA) was studied in normal subjects following rotational

  16. The Transformative Power of Taking an Inquiry Stance on Practice: Practitioner Research as Narrative and Counter-Narrative

    ERIC Educational Resources Information Center

    Ravitch, Sharon M.

    2014-01-01

    Within the ever-developing, intersecting, and overlapping contexts of globalization, top-down policy, mandates, and standardization of public and higher education, many conceptualize and position practitioner research as a powerful stance and a tool of social, communal, and educational transformation, a set of methodological processes that…

  17. Understanding developing country stances on post-2012 climate change negotiations: Comparative analysis of Brazil, China, India, Mexico, and South Africa

    Microsoft Academic Search

    Fang Rong

    2010-01-01

    An essential issue in future climate negotiations is how to bring developing countries on board. This paper proposes and applies the two-level interest-based model to analyze the factors that affect the likely stances of the “Plus Five” countries (Brazil, China, India, Mexico, and South Africa) on international climate negotiations. This study finds mitigation capability to be a crucial factor which

  18. How muscles define maximum running performance in lizards: an analysis using swing- and stance-phase muscles.

    PubMed

    Higham, Timothy E; Korchari, Paul G; McBrayer, Lance D

    2011-05-15

    Maximum locomotor performance is crucial for capturing prey, escaping predators and many other behaviors. However, we know little about what defines maximum performance in vertebrates. Muscles drive the movement of the limbs during locomotion, and thus likely play a major role in defining locomotor capacity. For lizards, the iliofibularis, a swing-phase muscle, is often linked to ecology and/or performance. However, stance-phase muscles likely limit performance given that they propel the animal. Using a small semi-arboreal lizard (Sceloporus woodi), we compared how swing- and stance-phase muscles relate to maximum running speed and acceleration. We employed both a level and vertical trackway to elicit ecologically relevant locomotor performance. Six individuals were filmed at 250 frames s?¹ in lateral view. Following performance trials, upper and lower hindlimbs were sectioned and assessed using histochemistry. Fast glycolytic, fast oxidative and slow oxidative fibers were detected and counted in the gastrocnemius (GA; stance phase) and iliofibularis (IF; swing phase) muscles. In addition, the mean fiber diameter for each fiber type in each muscle was determined, as was the fiber cross-sectional area. We found that properties of the GA, but not the IF, were positively correlated with performance. Interestingly, certain attributes of the GA were correlated with maximum vertical locomotion whereas others were correlated with maximum level locomotion. We conclude that stance phase, not swing phase, limits maximum performance in this species of lizard. In addition, we highlight the need to include properties of stance-phase muscles and a spectrum of ecologically relevant behaviors when attempting to correlate locomotor physiology with ecology and/or performance. PMID:21525314

  19. Sample entropy characteristics of movement for four foot types based on plantar centre of pressure during stance phase

    PubMed Central

    2013-01-01

    Background Motion characteristics of CoP (Centre of Pressure, the point of application of the resultant ground reaction force acting on the plate) are useful for foot type characteristics detection. To date, only few studies have investigated the nonlinear characteristics of CoP velocity and acceleration during the stance phase. The aim of this study is to investigate whether CoP regularity is different among four foot types (normal foot, pes valgus, hallux valgus and pes cavus); this might be useful for classification and diagnosis of foot injuries and diseases. To meet this goal, sample entropy, a measure of time-series regularity, was used to quantify the CoP regularity of four foot types. Methods One hundred and sixty five subjects that had the same foot type bilaterally (48 subjects with healthy feet, 22 with pes valgus, 47 with hallux valgus, and 48 with pes cavus) were recruited for this study. A Footscan® system was used to collect CoP data when each subject walked at normal and steady speed. The velocity and acceleration in medial-lateral (ML) and anterior-posterior (AP) directions, and resultant velocity and acceleration were derived from CoP. The sample entropy is the negative natural logarithm of the conditional probability that a subseries of length m that matches pointwise within a tolerance r also matches at the next point. This was used to quantify variables of CoP velocity and acceleration of four foot types. The parameters r (the tolerance) and m (the matching length) for sample entropy calculation have been determined by an optimal method. Results It has been found that in order to analyze all CoP parameters of velocity and acceleration during the stance phase of walking gait, for each variable there is a different optimal r value. On the contrary, the value m=4 is optimal for all variables. Sample entropies of both velocity and acceleration in AP direction were highly correlated with their corresponding resultant variables for r>0.91. The sample entropy of the velocity in AP direction was moderately correlated with the one of the acceleration in the same direction (r?0.673), as well as with the resultant acceleration (r?0.660). The sample entropy of resultant velocity was moderately correlated with the one of the acceleration in AP direction, as well as with the resultant acceleration (for the both r?0.689). Moderate correlations were found between variables for the left foot and their corresponding variables for the right foot. Sample entropies of AP velocity, resultant velocity, AP acceleration, and resultant acceleration of the right foot as well as AP velocity and resultant velocity of the left foot were, respectively, significantly different among the four foot types. Conclusions It can be concluded that the sample entropy of AP velocity (or the resultant velocity) of the left foot, ML velocity, resultant velocity, ML acceleration and resultant acceleration could serve for evaluation of foot types or selection of appropriate footwear. PMID:24112763

  20. Kinematics and Kinetics of Squat and Deadlift Exercises with Varying Stance Widths

    NASA Technical Reports Server (NTRS)

    DeWitt, John K.; Fincke, Renita S.; Logan, Rachel L.

    2011-01-01

    The primary motion of squat and deadlift exercise involves flexion and extension of the hips, knees, and ankles, but each exercise can be performed with variations in stance width. These variations may result in differing kinematics and ground reaction forces (GRF), which may in turn affect joint loading. PURPOSE: The purpose of this investigation was to compare ankle, knee, and hip kinematics and kinetics of normal squat (NS), wide-stance squat (WS), normal deadlift (ND), and sumo deadlift (SD). We hypothesized that hip joint kinematics and work at each joint would differ between exercise variations. METHODS: Six subjects (3 m/3 f; 70.0 plus or minus 13.7 kg; 168 plus or minus 9.9 cm) performed each lift in normal gravity on the ground-based version of the Advanced Resistive Exercise Device (ARED) used on the International Space Station. The ARED provided resistance with a combination vacuum tube/flywheel mechanism designed to replicate the gravitational and inertial forces of free weights. Subjects completed each lift with their 10-repetition maximum load. Kinematic data were collected at 250 Hz by a 12-camera motion-capture system (Smart-D, BTS Bioengineering, Milan, Italy), and GRF data were collected at 1000 Hz with independent force platforms for each leg (Model 9261, Kistler Instruments AG, Winterhur, Switzerland). All data were captured simultaneously on a single workstation. The right leg of a single lift for each motion was analyzed. Modeling software (OpenSim 2.2.0, Simbios, Palo Alto, CA) determined joint kinematics and net positive and negative work at each lower extremity joint. Total work was found as the sum of work across all joints and was normalized by system mass. Effect sizes and their 95% confidence intervals were computed between conditions. RESULTS: Peak GRF were similar for each lift. There were no differences between conditions in hip flexion range of motion (ROM). For hip adduction ROM, there were no differences between the NS, WS, and SD. However, hip adduction ROM was greater during the NS and SD than during the ND. Hip rotation ROM was greater during the WS than during the NS and SD, and was greater during the SD than during the ND. For knee and ankle flexion ROM, the ND, WS, and SD were not different, but ROM was greater during the NS than the ND and greater during the WS than the SD. Total eccentric work was greater during the WS than the SD. Otherwise, there were no differences in eccentric or concentric work between conditions. CONCLUSIONS: Although squat and deadlift exercises consist of similar motions, there are kinematic differences between them that depend on stance width. Total eccentric and concentric work are similar for different lifts, but differing kinematics may require activation of different musculature for each variation. With respect to each condition, in the ND the ROM of each joint tended to be less, and the WS tended to trade knee motion for hip motion. PRACTICAL APPLICATIONS: Knowledge of differences in kinematics and kinetics between different squat and deadlift variations is important for coaches and rehabilitation personnel to understand when prescribing exercise. Our results suggest that each variation of the squat and deadlift should be considered a separate exercise that may induce different long-term training effects.

  1. Comparison of ISO standard and TKR patient axial force profiles during the stance phase of gait.

    PubMed

    Lundberg, Hannah J; Ngai, Valentina; Wimmer, Markus A

    2012-03-01

    Preclinical endurance testing of total knee replacements (TKRs) is performed using International Organization for Standardization (ISO) load and motion protocols. The standards are based on data from normal subjects and may not sufficiently mimic in vivo implant conditions. In this study, a mathematical model was used to calculate the axial force profile of 30 TKR patients with two current implant types, 22 with NexGen and eight with Miller-Galante II Cruciate-Retaining TKRs, and statistically compare the axial force specified by the ISO standard to the TKR patients. Significant differences were found between the axial forces of both groups of TKR patients and the ISO standard at local maxima and minima points in the first half of stance. The force impulse (area under the axial force curve, representing cumulative loading) was smaller for the ISO standard than the TKR patients, but only for those with NexGen implants. Waveform analysis using the coefficient of multiple correlation showed that the ISO and TKR patient axial force profiles were similar. The combined effect of ISO standard compressive load and motion differences from TKR patients could explain some of the differences between the wear scars on retrieved tibial components and those tested in total joint simulators. PMID:22558837

  2. Cortical contributions to control of posture during unrestricted and restricted stance.

    PubMed

    Murnaghan, Chantelle D; Squair, Jordan W; Chua, Romeo; Inglis, J Timothy; Carpenter, Mark G

    2014-05-01

    There is very little consensus regarding the mechanisms underlying postural control. Whereas some theories suggest that posture is controlled at lower levels (i.e., brain stem and spinal cord), other theories have proposed that upright stance is controlled using higher centers, including the motor cortex. In the current investigation, we used corticomuscular coherence (CMC) to investigate the relationship between cortical and shank muscle activity during conditions of unrestricted and restricted postural sway. Participants were instructed to stand as still as possible in an apparatus that allowed the center of mass to move freely ("Unlocked") or to be stabilized ("Locked") without subject awareness. EEG (Cz) and electromyography (soleus and lateral/medial gastrocnemii) were collected and used to estimate CMC over the Unlocked and Locked periods. Confirming our previous results, increases in center of pressure (COP) displacements were observed in 9 of 12 participants in the Locked compared with Unlocked condition. Across these 9 participants, CMC was low or absent in both the Unlocked and Locked conditions. The results from the current study suggest that this increase is not associated with an increase in the relationship between cortical and shank muscle activities. Rather, it may be that increases in COP displacement with locking are mediated by subcortical structures as a means of increasing sway to provide the central nervous system with a critical level of sensory information. PMID:24523526

  3. Comparison of ISO Standard and TKR Patient Axial Force Profiles during the Stance Phase of Gait

    PubMed Central

    Lundberg, Hannah J.; Ngai, Valentina; Wimmer, Markus A.

    2012-01-01

    Preclinical endurance testing of total knee replacements (TKRs) is performed using International Organization for Standardization (ISO) load and motion protocols. The standards are based on data from normal subjects and may not sufficiently mimic in vivo implant conditions. In this study, a mathematical model was used to calculate the axial force profile of 30 TKR patients with two current implant types, 22 with NexGen and eight with Miller-Galante II Cruciate-Retaining TKRs, and statistically compare the axial force specified by the ISO standard to the TKR patients. Significant differences were found between the axial forces of both groups of TKR patients and the ISO standard at local maxima and minima points in the first half of stance. The force impulse (area under the axial force curve, representing cumulative loading) was smaller for the ISO standard than the TKR patients, but only for those with NexGen implants. Waveform analysis using the coefficient of multiple correlation showed that the ISO and TKR patient axial force profiles were similar. The combined effect of ISO standard compressive load and motion differences from TKR patients could explain some of the differences between the wear scars on retrieved tibial components and those tested in total joint simulators. PMID:22558837

  4. Preferred placement of the feet during quiet stance: development of a standardized foot placement for balance testing

    Microsoft Academic Search

    WE McIlroy; BE Maki

    1997-01-01

    Objective. To establish a standardized stance position for balance testing based on average preferred foot placement, and to compare this to existing standards.Design. Cross-sectional study.Background. It has been shown that the orientation of the feet can have a marked influence on the results obtained during balance testing, prompting the need for standardized foot positioning. Unfortunately, current recommendations do not appear

  5. The Human Ankle-Foot Complex as a Multi-Configurable Mechanism during the Stance Phase of Walking

    Microsoft Academic Search

    Amaraporn Boonpratatong; Lei Ren

    2010-01-01

    The objective of this study is to investigate the biomechanical functions of the human ankle-foot complex during the stance phase of walking. The three-dimensional (3D) gait measurement was conducted by using a 3D infrared multi-camera system and a force plate array to record the Ground Reaction Forces (GRF) and segmental motions simultaneously. The ankle-foot complex was modelled as a four-segment

  6. What does head movement tell about the minimum number of mechanical degrees of freedom in quiet human stance?

    Microsoft Academic Search

    Michael Günther; Otto Müller; Reinhard Blickhan

    In this study, we checked experimentally whether anterior–posterior accelerations of the head during quiet human stance are\\u000a usually below or above known thresholds of the otolith sensor. Thereto, we measured head kinematics with high spatial resolution.\\u000a Furthermore, we used both these experimental data and computer simulations of two double inverted pendulum (DIP) models in\\u000a order to verify the validity of

  7. Non-linear stimulus-response behavior of the human stance control system is predicted by optimization of a system with sensory and motor noise

    Microsoft Academic Search

    Herman van der Kooij; Robert J. Peterka

    2011-01-01

    We developed a theory of human stance control that predicted (1) how subjects re-weight their utilization of proprioceptive\\u000a and graviceptive orientation information in experiments where eyes closed stance was perturbed by surface-tilt stimuli with\\u000a different amplitudes, (2) the experimentally observed increase in body sway variability (i.e. the “remnant” body sway that\\u000a could not be attributed to the stimulus) with increasing

  8. Influence of physicians' life-stance on attitudes towards end-of-life decisions and actual end-of-life decision-making in six countries

    Microsoft Academic Search

    Joachim Cohen; J van Delden; Freddy Mortier; Rurik Lofmark; Michael Norup; Colleen M Cartwright; Karin Faisst; C Canova; J Bilsen

    2008-01-01

    Aim: To examine how physicians’ life stances affect their attitudes to end-of-life decisions and their actual end-of-life decision-making.\\u000aMethods: Practising physicians from various specialties involved in the care of dying patients in Belgium, Denmark, The Netherlands, Sweden, Switzerland and Australia received structured questionnaires on end-of-life care, which included questions about their life stance. Response rates ranged from 53% in Australia

  9. Estimation of Quasi-Stiffness of the Human Hip in the Stance Phase of Walking

    PubMed Central

    Shamaei, Kamran; Sawicki, Gregory S.; Dollar, Aaron M.

    2013-01-01

    This work presents a framework for selection of subject-specific quasi-stiffness of hip orthoses and exoskeletons, and other devices that are intended to emulate the biological performance of this joint during walking. The hip joint exhibits linear moment-angular excursion behavior in both the extension and flexion stages of the resilient loading-unloading phase that consists of terminal stance and initial swing phases. Here, we establish statistical models that can closely estimate the slope of linear fits to the moment-angle graph of the hip in this phase, termed as the quasi-stiffness of the hip. Employing an inverse dynamics analysis, we identify a series of parameters that can capture the nearly linear hip quasi-stiffnesses in the resilient loading phase. We then employ regression analysis on experimental moment-angle data of 216 gait trials across 26 human adults walking over a wide range of gait speeds (0.75–2.63 m/s) to obtain a set of general-form statistical models that estimate the hip quasi-stiffnesses using body weight and height, gait speed, and hip excursion. We show that the general-form models can closely estimate the hip quasi-stiffness in the extension (R2?=?92%) and flexion portions (R2?=?89%) of the resilient loading phase of the gait. We further simplify the general-form models and present a set of stature-based models that can estimate the hip quasi-stiffness for the preferred gait speed using only body weight and height with an average error of 27% for the extension stage and 37% for the flexion stage. PMID:24349136

  10. Using Argument-Driven Inquiry to enhance students' argument sophistication when supporting a stance in the context of Socioscientific Issues

    NASA Astrophysics Data System (ADS)

    Grooms, Jonathon A.

    This quasi-experimental study assesses the extent to which the Argument-Driven Inquiry (ADI) instructional model enhances undergraduate students' abilities to generate quality arguments supporting their stance in the context of a Socioscientific Issue (SSI) as compared to students experiencing a traditional style of instruction. Enhancing the quality of undergraduate students' arguments in the context of SSI can serve as an indirect measure of their scientific literacy and their ability to make sound decisions on issues that are inherently scientific but also involve social implications. Data collected in this study suggest that the undergraduate students experiencing the ADI instruction more readily provide rationales in their arguments supporting their decisions regarding two SSI-tasks as compared to a group of undergraduate students experiencing traditional instruction. This improvement in argument quality and gain in scientific literacy was achieved despite the overall lower SSI related content knowledge of the ADI students. Furthermore, the gap between the argument quality of those students with high versus low SSI related content knowledge was closed within the ADI group, while the same gap persisted post-intervention within the traditional instruction students. The role of students' epistemological sophistication was also investigated, which showed that neither instructional strategy was effective at shifting students' epistemological sophistication toward an evaluativist stance. However, the multiplists within the ADI group were able to significantly increase the sophistication of their arguments whereas the traditional students were not. There were no differences between the quality of arguments generated by the evaluativist students with either the treatment or comparison groups. Finally, the nature of the justifications used by the students revealed that the students (both comparison and treatment groups) did not invoke science-based justifications when supporting their stance, despite students' self-reports that scientific content knowledge accounted for the greatest influence on their stance, related to the SSI tasks. The results of this study suggest that the scientific habits of mind the students learned in the context of ADI investigations are transferred to the novel SSI contexts. Implications for the use of argument-based instructional models to enhance the generation of socioscientific arguments and to promote the development of scientific literacy are also discussed.

  11. Intra-articular Contact Stress Distributions at the Ankle throughout Stance Phase – Patient-Specific Finite Element Analysis as a Metric of Degeneration Propensity

    PubMed Central

    Anderson, Donald D.; Goldsworthy, Jane K.; Shivanna, Kiran; Grosland, Nicole M.; Pedersen, Douglas R.; Thomas, Thaddeus P.; Tochigi, Yuki; Marsh, J.Lawrence; Brown, Thomas D.

    2008-01-01

    A contact finite element (FE) formulation is introduced, amenable to patient-specific analysis of cumulative cartilage mechano-stimulus attributable to habitual functional activity. CT scans of individual human ankles are segmented to delineate bony margins. Each bone surface is projected outward to create a second surface, and the intervening volume is then meshed with continuum hexahedral elements. The tibia is positioned relative to the talus into a weight-bearing apposition. The articular members are first engaged under light preload, then plantar-/dorsi-flexion kinematics and resultant loadings are input for serial FE solutions at 13 instants of the stance phase of level walking gait. Cartilage stress histories are post-processed to recover distributions of cumulative stress-time mechano-stimulus, a metric of degeneration propensity. Consistency in computed contact stress exposures presented for seven intact ankles stood in contrast to the higher magnitude and more focal exposures in an incongruously reduced tibial plafond fracture. This analytical procedure provides patient-specific estimates of degeneration propensity due to various mechanical abnormalities, and it provides a platform from which the mechanical efficacy of alternative surgical interventions can be estimated. PMID:16520960

  12. A robust 3D finite element simulation of human proximal femur progressive fracture under stance load with experimental validation.

    PubMed

    Hambli, Ridha; Allaoui, Samir

    2013-12-01

    Clinical implementation of quantitative computed tomography-based finite element analysis (QCT/FEA) of proximal femur (hip) fractures requires (i) to develop a bone material behavior able to describe the progressive fracturing process until complete failure of the hip. And (ii) to validate the model with realistic test data that represent typical hip fractures. The objective of the current study was to develop and experimentally validate an accurate 3D finite element (FE) model coupled to a quasi-brittle damage law to simulate human proximal femur fracture considering the initiation and progressive propagation of multiple cracks phases under quasi-static load. The model is based on continuum damage mechanics that can predict hip fracture in more adequate physical terms than criteria-based fracture models. In order to validate the model, ten human proximal femurs were tested until complete fracture under one-legged stance quasi-static load. QCT/FE models were generated and FE simulations were performed on these femurs with the same applied loads and boundary conditions than in the stance experiments. The proposed FE model leads to excellent agreement (R(2) = 0.9432) between predicted and measured results concerning the shape of the force-displacement curve (yielding and fracturing) and the profile of the fractured edge. The motivation of this work was to propose a FE model for possible clinical use with a good compromise between complexity and capability of the simulation. PMID:23864338

  13. Restoration of Stance Phase Knee Flexion during Walking after Spinal Cord Injury using a Variable Impedance Orthosis

    PubMed Central

    Bulea, Thomas C.; Kobetic, Rudi; Triolo, Ronald. J.

    2013-01-01

    A hybrid neuroprosthesis (HNP) combines lower extremity bracing with functional neuromuscular stimulation (FNS) to restore walking function and enhance the efficiency of ambulation. This report details the development of a novel HNP containing a variable impedance knee mechanism (VIKM) capable of supporting the knee against collapse while allowing controlled stance phase knee flexion. The design of a closed loop, finite state controller for coordination of VIKM activity with FNS-driven gait is presented. The controller is verified in testing during able bodied gait. The improved functionality provided by this system has the potential to delay the onset of fatigue and to expand FNS driven gait to allow walking over uneven terrains and down stairs. PMID:22254383

  14. Changes in length of the plantar aponeurosis during the stance phase of gait--an in vivo dynamic fluoroscopic study.

    PubMed

    Fessel, G; Jacob, H A C; Wyss, Ch; Mittlmeier, Th; Müller-Gerbl, M; Büttner, A

    2014-12-01

    In locomotion, ligaments and muscles have been recognized to support the arch of the foot. However, it remains unclear to what extent the passive and active structures of the lower extremity support the longitudinal arch of the foot during walking. In this study, the mechanical function of the plantar aponeurosis (PA) is investigated by elongation measurements in vivo during the stance phase of gait, in combination with measurements of the mechanical properties of the PA in vitro. Fluoroscopy was used to measure the dynamic changes in PA length and the angular motion of the metatarsophalangeal joint of the first ray, measured during the stance phase (StPh) in 11 feet. Simultaneously, ground forces were measured. Additionally, four cadaver feet delivered topographic information relating to the PA, and three autopsy specimens of PA served to determine the in vitro mechanical properties of PA. The present study revealed a non-significant peak average PA shortening of 0.48% at about 32.5% StPh, followed by a significant average peak elongation of 3.6% at 77.5% StPh. This average peak elongation of 3.6% corresponds to a force of 292N, as estimated by mechanical testing of the autopsy PA specimens. Considering the maximum peak elongation measured in one volunteer of 4.8% at 76% StPh, a peak PA load of 488N might be expected. Hence, with an average body weight of 751N, as allocated to the 11 investigated feet, this maximum peak force would correspond to about 0.65×body weight. As far as we are aware, this is the first report on a dynamic fluoroscopic study of the PA in gait with an appreciable number of feet (11 feet). In conclusion, muscles contribute to support of the longitudinal arch of the foot and can possibly relax the PA during gait. The 'windlass effect' for support of the arch in this context is therefore questionable. PMID:25113063

  15. Figure 1. Ankle behavior can be approximated by a linear torsional spring in the progression stage of the stance phase of normal gait.

    E-print Network

    Dollar, Aaron M.

    walking, but deviates from normal as walking speed increases [5]. In passive ankle-foot orthoses (AFOs explored the dynamics of the ankle joint, including active and passive mechanics ([11]- [14]). These works in the progression stage of stance during normal walking. We show that the torque/angle behavior of the ankle during

  16. Origins of Children's Externalizing Behavior Problems in Low-Income Families: Toddlers’ Willing Stance toward their Mothers as the Missing Link

    PubMed Central

    Kochanska, Grazyna; Kim, Sanghag; Boldt, Lea J.

    2013-01-01

    Although children's active role in socialization has been long acknowledged, relevant research has typically focused on children's difficult temperament or negative behaviors that elicit coercive and adversarial processes, largely overlooking their capacity to act as positive, willing, even enthusiastic, active socialization agents. We studied the willing, receptive stance toward their mothers in 186 24-44-month-old children in a low-income sample. Confirmatory Factor Analysis supported a latent construct of willing stance, manifested as children's responsiveness to mothers in naturalistic interactions, responsive imitation in teaching contexts, and committed compliance with maternal prohibitions, all observed in the laboratory. Structural Equation Modeling analyses confirmed that ecological adversity undermined maternal responsiveness and responsiveness, in turn, was linked to children's willing stance. A compromised willing stance predicted externalizing behavior problems, assessed 10 months later, and fully mediated the links between maternal responsiveness and those outcomes. Ecological adversity had a direct, unmediated effect on internalizing behavior problems. Considering children's active role as willing, receptive agents capable of embracing parental influence can lead to a more complete understanding of detrimental mechanisms that link ecological adversity with antisocial developmental pathways. It can also inform research on the normative socialization process, consistent with the objectives of developmental psychopathology. PMID:24229537

  17. Effect of Frontal Plane Tibiofemoral Angle on the Stress and Strain at the Knee Cartilage during the Stance Phase of Gait

    E-print Network

    Vaziri, Ashkan

    Effect of Frontal Plane Tibiofemoral Angle on the Stress and Strain at the Knee Cartilage during ABSTRACT: Subject-specific three-dimensional finite element models of the knee joint were created and used in the knee cartilage during the stance phase of the gait cycle. Knee models of three subjects with different

  18. Comparison of segmental linear and angular momentum transfers in two-handed backhand stroke stances for different skill level tennis players.

    PubMed

    Wang, Lin-Hwa; Lin, Hwai-Ting; Lo, Kuo-Cheng; Hsieh, Yung-Chun; Su, Fong-Chin

    2010-07-01

    The purpose of this study was to investigate the differences of momentum transfer from the trunk and upper extremities to the racket between open and square stances for different skill levels players in the two-handed backhand stroke. The motion capture system with twenty-one reflective markers attached on anatomic landmarks of the subject was used for two-handed backhand stroke motion data collection. Twelve subjects were divided into an advanced group and an intermediate group based on skill level. The three-dimensional linear and angular momentums of the trunk, upper arm, forearm, hand and racket were used for kinetic chain analysis. Results showed that all players with the square stance had significantly larger backward linear momentum contribution in trunk and upper arm than with the open stance (p<.05) irrespective of playing level. However, the external rotation angular momentum of the shoulder joint was significantly larger with an open stance than with a square stance (p=.047). Comparison of playing levels showed that the intermediate group performed higher linear momentum in three components of the trunk, upper arm backward linear momentum, and trunk right bending angular momentum than the advanced group significantly (p<.05). The advanced group reduces trunk linear movement to keep stability and applies trunk and linkage segment rotation to generate backhand stroke power. The advanced group also has a quick backswing for increasing acceleration and maintains longer in the follow-through phase for shock energy absorption. This information could improve training protocol design for teaching the two-handed backhand stroke and teaching players, especially beginners, how to make an effective stroke. PMID:19837630

  19. The Role of Knee Positioning and Range-of-Motion on the Closed-Stance Forehand Tennis Swing

    PubMed Central

    Nesbit, Steven M.; Serrano, Monika; Elzinga, Mike

    2008-01-01

    This paper discusses the role of knee positioning and range-of- motion on the closed-stance forehand tennis swing. The analyses of tennis swing mechanics were performed using a computer model comprised of a full-body model of a human and an inertial model of a racket. The model was driven by subject forehand swings (16 female college-level subjects) recorded with a high-speed digital motion analysis system. The study discovered that both initial knee positioning and range-of-motion were positively related to racket velocity and characteristic of more skilled players. The direct effects of knee positioning and range-of-motion on racket movement are minimal, however there are several indirect biomechanical effects on the forehand motion such as movement of the body mass center, work of the knee, hip and back joints, and the angular range-of-motion of the hips and torso. Some of these indirect effects were related to racket velocity and characteristic of more skilled players. Factors that influenced knee positioning and range-of-motion include years of playing, amount of coaching, and body style. Efforts to both increase and restrict the knee movements of the subjects resulted in substantially lower racket velocities (and other detrimental biomechanical effects) implying that there may be optimal knee positions and range-of-motion for a given subject. The most skilled subject exhibited a high degree of consistency of knee positioning and range-of-motion. This subject adjusted for varying ball height through modified initial knee positioning while maintaining fairly constant ranges-of-motion. Key pointsInitial knee positioning and range-of-motion were positively related to racket velocity and characteristic of more skilled players for the closed stance forehand motion.Knee positioning and range-of-motion had several indirect biomechanical effects on the forehand motion such as movement of the body mass center, work of the knee, hip and back joints, and the angular range-of-motion of the hips and torso.Efforts to both increase and restrict the knee movements resulted in substantially lower racket velocities implying that there may be optimal knee positions and range-of-motion for a given subject.The most skilled subject exhibited a high degree of consistency of knee positioning and range-of-motion. This subject adjusted for varying ball height through modified initial knee positioning while maintaining fairly constant ranges-of-motion. PMID:24150143

  20. First trial and StartReact effects induced by balance perturbations to upright stance.

    PubMed

    Campbell, A D; Squair, J W; Chua, R; Inglis, J T; Carpenter, M G

    2013-11-01

    Postural responses (PR) to a balance perturbation differ between the first and subsequent perturbations. One explanation for this first trial effect is that perturbations act as startling stimuli that initiate a generalized startle response (GSR) as well as the PR. Startling stimuli, such as startling acoustic stimuli (SAS), are known to elicit GSRs, as well as a StartReact effect, in which prepared movements are initiated earlier by a startling stimulus. In this study, a StartReact effect paradigm was used to determine if balance perturbations can also act as startle stimuli. Subjects completed two blocks of simple reaction time trials involving wrist extension to a visual imperative stimulus (IS). Each block included 15 CONTROL trials that involved a warning cue and subsequent IS, followed by 10 repeated TEST trials, where either a SAS (TESTSAS) or a toes-up support-surface rotation (TESTPERT) was presented coincident with the IS. StartReact effects were observed during the first trial in both TESTSAS and TESTPERT conditions as evidenced by significantly earlier wrist movement and muscle onsets compared with CONTROL. Likewise, StartReact effects were observed in all repeated TESTSAS and TESTPERT trials. In contrast, GSRs in sternocleidomastoid and PRs were large in the first trial, but significantly attenuated over repeated presentation of the TESTPERT trials. Results suggest that balance perturbations can act as startling stimuli. Thus first trial effects are likely PRs which are superimposed with a GSR that is initially large, but habituates over time with repeated exposure to the startling influence of the balance perturbation. PMID:23945786

  1. Influence of Electrotactile Tongue Feedback on Controlling Upright Stance during Rotational and/or Translational Sway-referencing with Galvanic Vestibular Stimulation

    NASA Technical Reports Server (NTRS)

    Wood, Scott J.; Tyler, Mitchell E.; Bach-y-Rita, Paul; MacDougall, Hamish G.; Moore, Steven T.; Stallings, Valerie L.; Paloski, William H.; Black, F. Owen

    2007-01-01

    Integration of multi-sensory inputs to detect tilts relative to gravity is critical for sensorimotor control of upright orientation. Displaying body orientation using electrotactile feedback to the tongue has been developed by Bach-y-Rita and colleagues as a sensory aid to maintain upright stance with impaired vestibular feedback. MacDougall et al. (2006) recently demonstrated that unpredictably varying Galvanic vestibular stimulation (GVS) significantly increased anterior-posterior (AP) sway during rotational sway referencing with eyes closed. The purpose of this study was to assess the influence of electrotactile feedback on postural control performance with pseudorandom binaural bipolar GVS. Postural equilibrium was measured with a computerized hydraulic platform in 10 healthy adults (6M, 4F, 24-65 y). Tactile feedback (TF) of pitch and roll body orientation was derived from a two-axis linear accelerometer mounted on a torso belt and displayed on a 144-point electrotactile array held against the anterior dorsal tongue (BrainPort, Wicab, Inc., Middleton, WI). Subjects were trained to use TF by voluntarily swaying to draw figures on their tongue, both with and without GVS. Subjects were required to keep the intraoral display in their mouths on all trials, including those that did not provide TF. Subjects performed 24 randomized trials (20 s duration with eyes closed) including four support surface conditions (fixed, rotational sway-referenced, translating the support surface proportional to AP sway, and combined rotational-translational sway-referencing), each repeated twice with and without GVS, and with combined GVS and TF. Postural performance was assessed using deviations from upright (peak-to-peak and RMS sway) and convergence toward stability limits (time and distance to base of support boundaries). Postural stability was impaired with GVS in all platform conditions, with larger decrements in performance during trials with rotation sway-referencing. Electrotactile feedback improved performance with GVS toward non-GVS levels, again with the greatest improvement during trials with rotation sway-referencing. These results demonstrate the effectiveness of tongue electrotactile feedback in providing sensory substitution to maintain postural stability with distorted vestibular input.

  2. Test-retest reliability of centre of foot pressure measures to assess postural control during unperturbed stance.

    PubMed

    Pinsault, Nicolas; Vuillerme, Nicolas

    2009-03-01

    Centre of foot pressure (CoP) measures, computed from a force platform, are commonly used to assess individual's postural control during unperturbed stance. The purpose of the present study was to evaluate the effect of the number of trial recordings on the test-retest reliability of CoP measures and to determine the optimum number of trial recordings required to maximise their test-retest reliability. Ten young healthy adults were asked to stand upright, eyes closed, as still as possible on a force platform allowing measuring the CoP displacements. Two sessions of ten 30s trials were performed with 1h rest in between. Intra-class correlation coefficient (ICC) with 95% confidence interval and Bland and Altman analysis were used as statistical method for assessing test-retest reliability of CoP measures. These analyses were conducted on both (1) non-normalized CoP measures and (2) CoP measures normalized relative to the subjects' anthropometric properties (height, weight and body mass index). Results show that ICCs generally increase as the number of trials used to compute CoP measures increases. Interestingly, three 30s trial recordings are sufficient to ensure excellent test-retest reliability of 12 CoP measures widely employed in clinical practice, namely two-dimensional CoP parameters (surface area, range, mean and maximal velocities of the CoP displacements) and one-dimensional mediolateral and anteroposterior CoP parameters (variance, range, mean and maximal velocities). The present findings could have implications in clinical and rehabilitative areas. PMID:18835738

  3. Estimation of Quasi-Stiffness and Propulsive Work of the Human Ankle in the Stance Phase of Walking

    PubMed Central

    Shamaei, Kamran; Sawicki, Gregory S.; Dollar, Aaron M.

    2013-01-01

    Characterizing the quasi-stiffness and work of lower extremity joints is critical for evaluating human locomotion and designing assistive devices such as prostheses and orthoses intended to emulate the biological behavior of human legs. This work aims to establish statistical models that allow us to predict the ankle quasi-stiffness and net mechanical work for adults walking on level ground. During the stance phase of walking, the ankle joint propels the body through three distinctive phases of nearly constant stiffness known as the quasi-stiffness of each phase. Using a generic equation for the ankle moment obtained through an inverse dynamics analysis, we identify key independent parameters needed to predict ankle quasi-stiffness and propulsive work and also the functional form of each correlation. These parameters include gait speed, ankle excursion, and subject height and weight. Based on the identified form of the correlation and key variables, we applied linear regression on experimental walking data for 216 gait trials across 26 subjects (speeds from 0.75–2.63 m/s) to obtain statistical models of varying complexity. The most general forms of the statistical models include all the key parameters and have an R2 of 75% to 81% in the prediction of the ankle quasi-stiffnesses and propulsive work. The most specific models include only subject height and weight and could predict the ankle quasi-stiffnesses and work for optimal walking speed with average error of 13% to 30%. We discuss how these models provide a useful framework and foundation for designing subject- and gait-specific prosthetic and exoskeletal devices designed to emulate biological ankle function during level ground walking. PMID:23555839

  4. Estimation of quasi-stiffness and propulsive work of the human ankle in the stance phase of walking.

    PubMed

    Shamaei, Kamran; Sawicki, Gregory S; Dollar, Aaron M

    2013-01-01

    Characterizing the quasi-stiffness and work of lower extremity joints is critical for evaluating human locomotion and designing assistive devices such as prostheses and orthoses intended to emulate the biological behavior of human legs. This work aims to establish statistical models that allow us to predict the ankle quasi-stiffness and net mechanical work for adults walking on level ground. During the stance phase of walking, the ankle joint propels the body through three distinctive phases of nearly constant stiffness known as the quasi-stiffness of each phase. Using a generic equation for the ankle moment obtained through an inverse dynamics analysis, we identify key independent parameters needed to predict ankle quasi-stiffness and propulsive work and also the functional form of each correlation. These parameters include gait speed, ankle excursion, and subject height and weight. Based on the identified form of the correlation and key variables, we applied linear regression on experimental walking data for 216 gait trials across 26 subjects (speeds from 0.75-2.63 m/s) to obtain statistical models of varying complexity. The most general forms of the statistical models include all the key parameters and have an R(2) of 75% to 81% in the prediction of the ankle quasi-stiffnesses and propulsive work. The most specific models include only subject height and weight and could predict the ankle quasi-stiffnesses and work for optimal walking speed with average error of 13% to 30%. We discuss how these models provide a useful framework and foundation for designing subject- and gait-specific prosthetic and exoskeletal devices designed to emulate biological ankle function during level ground walking. PMID:23555839

  5. US Definitions, Current Use, and FDA Stance on Use of Platelet-Rich Plasma in Sports Medicine.

    PubMed

    Beitzel, Knut; Allen, Donald; Apostolakos, John; Russell, Ryan P; McCarthy, Mary Beth; Gallo, Gregory J; Cote, Mark P; Mazzocca, Augustus D

    2015-02-01

    With increased utilization of platelet-rich plasma (PRP), it is important for clinicians to understand the United States, the Food and Drug Administration (FDA) regulatory role and stance on PRP. Blood products such as PRP fall under the prevue of FDA's Center for Biologics Evaluation and Research (CBER). CBER is responsible for regulating human cells, tissues, and cellular and tissue-based products. The regulatory process for these products is described in the FDA's 21 CFR 1271 of the Code of Regulations. Under these regulations, certain products including blood products such as PRP are exempt and therefore do not follow the FDA's traditional regulatory pathway that includes animal studies and clinical trials. The 510(k) application is the pathway used to bring PRP preparation systems to the market. The 510(k) application allows devices that are "substantially equivalent" to a currently marketed device to come to the market. There are numerous PRP preparation systems on the market today with FDA clearance; however, nearly all of these systems have 510(k) clearance for producing platelet-rich preparations intended to be used to mix with bone graft materials to enhance bone graft handling properties in orthopedic practices. The use of PRP outside this setting, for example, an office injection, would be considered "off label." Clinicians are free to use a product off-label as long as certain responsibilities are met. Per CBER, when the intent is the practice of medicine, clinicians "have the responsibility to be well informed about the product, to base its use on firm scientific rationale and on sound medical evidence, and to maintain records of the product's use and effects." Finally, despite PRP being exempted, the language in 21 CFR 1271 has caused some recent concern over activated PRP; however to date, the FDA has not attempted to regulate activated PRP. Clinicians using activated PRP should be mindful of these concerns and continued to stay informed. PMID:25268794

  6. Visual-Somatosensory Integration and Balance: Evidence for Psychophysical Integrative Differences in Aging

    PubMed Central

    Mahoney, Jeannette R.; Holtzer, Roee; Verghese, Joe

    2014-01-01

    Research detailing multisensory integration (MSI) processes in aging and their association with clinically relevant outcomes is virtually non-existent. To our knowledge, the relationship between MSI and balance has not been well-established in aging. Given known alterations in unisensory processing with increasing age, the aims of the current study were to determine differential behavioral patterns of MSI in aging and investigate whether MSI was significantly associated with balance and fall-risk. Seventy healthy older adults (M = 75 years; 58% female) participated in the current study. Participants were instructed to make speeded responses to visual, somatosensory, and visual-somatosensory (VS) stimuli. Based on reaction times (RTs) to all stimuli, participants were classified into one of two groups (MSI or NO MSI), depending on their MSI RT benefit. Static balance was assessed using mean unipedal stance time. Overall, results revealed that RTs to VS stimuli were significantly shorter than those elicited to constituent unisensory conditions. Further, the current experimental design afforded differential patterns of multisensory processing, with 75% of the elderly sample demonstrating multisensory enhancements. Interestingly, 25% of older adults did not demonstrate multisensory RT facilitation; a finding that was attributed to extremely fast RTs overall and specifically in response to somatosensory inputs. Individuals in the NO MSI group maintained significantly better unipedal stance times and reported less falls, compared to elders in the MSI group. This study reveals the existence of differential patterns of multisensory processing in aging, while describing the clinical translational value of MSI enhancements in predicting balance and falls risk. PMID:25102664

  7. Time

    ERIC Educational Resources Information Center

    Circle, David

    2005-01-01

    When a teacher gives their time to a student, it is more significant to that student than anything else one could do for him or her. Music teachers deal with time all the time. Someone once said that "time is like money: we never have enough." This may seem true; however, time is not like money. One can make more money, but one cannot "make time."…

  8. Balance in single-limb stance in healthy subjects – reliability of testing procedure and the effect of short-duration sub-maximal cycling

    PubMed Central

    Ageberg, Eva; Roberts, David; Holmström, Eva; Fridén, Thomas

    2003-01-01

    Background To assess balance in single-limb stance, center of pressure movements can be registered by stabilometry with force platforms. This can be used for evaluation of injuries to the lower extremities. It is important to ensure that the assessment tools we use in the clinical setting and in research have minimal measurement error. Previous studies have shown that the ability to maintain standing balance is decreased by fatiguing exercise. There is, however, a need for further studies regarding possible effects of general exercise on balance in single-limb stance. The aims of this study were: 1) to assess the test-retest reliability of balance variables measured in single-limb stance on a force platform, and 2) to study the effect of exercise on balance in single-limb stance, in healthy subjects. Methods Forty-two individuals were examined for test-retest reliability, and 24 individuals were tested before (pre-exercise) and after (post-exercise) short-duration, sub-maximal cycling. Amplitude and average speed of center of pressure movements were registered in the frontal and sagittal planes. Mean difference between test and retest with 95% confidence interval, the intraclass correlation coefficient, and the Bland and Altman graphs with limits of agreement, were used as statistical methods for assessing test-retest reliability. The paired t-test was used for comparisons between pre- and post-exercise measurements. Results No difference was found between test and retest. The intraclass correlation coefficients ranged from 0.79 to 0.95 in all stabilometric variables except one. The limits of agreement revealed that small changes in an individual's performance cannot be detected. Higher values were found after cycling in three of the eight stabilometric variables. Conclusions The absence of systematic variation and the high ICC values, indicate that the test is reliable for distinguishing among groups of subjects. However, relatively large differences in an individual's balance performance would be required to confidently state that a change is real. The higher values found after cycling, indicate compensatory mechanisms intended to maintain balance, or a decreased ability to maintain balance. It is recommended that average speed and DEV 10; the variables showing the best reliability and effects of exercise, be used in future studies. PMID:12831402

  9. Frontal Plane Motion of the Pelvis and Hip during Gait Stance Discriminates Children with Diplegia Levels I and II of the GMFCS

    PubMed Central

    Kirkwood, Renata Noce; Franco, Rosa de Lourdes Lima Dias; Furtado, Sheyla Cavalcanti; Barela, Ana Maria Forti; Deluzio, Kevin John; Mancini, Marisa Cotta

    2012-01-01

    Objective. To determine if gait waveform could discriminate children with diplegic cerebral palsy of the GMFCS levels I and II. Patients. Twenty-two children with diplegia, 11 classified as level I and 11 as level II of the GMFCS, aged 7 to 12 years. Methods. Gait kinematics included angular displacement of the pelvis and lower limb joints during the stance phase. Principal components (PCs) analyses followed by discriminant analysis were conducted. Results. PC1s of the pelvis and hip in the frontal plane differ significantly between groups and captured 80.5% and 86.1% of the variance, respectively. PC1s captured the magnitude of the pelvic obliquity and hip adduction angle during the stance phase. Children GMFCS level II walked with reduced pelvic obliquity and hip adduction angles, and these variables could discriminate the groups with a cross-validation of 95.5%. Conclusion. Reduced pelvic obliquity and hip adduction were observed between children GMFCS level II compared to level I. These results could help the classification process of mild-to-moderate children with diplegia. In addition, it highlights the importance of rehabilitation programs designed to improve pelvic and hip mobility in the frontal plane of diplegic cerebral palsy children level II of the GMFCS. PMID:22792478

  10. Finding programming errors earlier by evaluating runtime monitors ahead-of-time

    Microsoft Academic Search

    Eric Bodden; Patrick Lam; Laurie J. Hendren

    2008-01-01

    Runtime monitoring allows programmers to validate, for in- stance, the proper use of application interfaces. Given a property specification, a runtime monitor tracks appropri- ate runtime events to detect violations and possibly execute recovery code. Although powerful, runtime monitoring in- spects only one program run at a time and so may require many program runs to find errors. Therefore, in

  11. NICHQ Vanderbilt Assessment Scale--TEACHER Informant Teacher's Name: _______________________________ Class Time: ___________________ Class Name/Period: ________________

    E-print Network

    Borenstein, Elhanan

    : _______________________________ Class Time: ___________________ Class Name/Period: ________________ Today's Date: ___________ Child. Loses temper 0 1 2 3 20. Actively defies or refuses to comply with adult's requests or rules 0 1 2 3 21 circum- stances, may be appropriate. Copyright ©2002 American Academy of Pediatrics and National

  12. The intertextual origins of public opinion: constructing Ebonics in the New York Times

    Microsoft Academic Search

    Jennifer Sclafani

    2008-01-01

    In this article, I revisit the 1996 Oakland School Board (OSB) resolution on Ebonics and perform a discourse analysis of the NeW York Times coverage of the decision. Using the framework of intertextuality, I consider how reported speech allows authors to appropriate authority and construct various stances toward the OSB decision. I discuss how other framing devices work in tandem

  13. Philip Morris's website and television commercials use new language to mislead the public into believing it has changed its stance on smoking and disease

    PubMed Central

    Friedman, Lissy C

    2007-01-01

    Objectives This paper analyses Philip Morris's evolving website and the legal strategies employed in its creation and dissemination. Methods Internal tobacco documents were searched and examined and their substance verified and triangulated using media accounts, legal and public health research papers, and visits to Philip Morris's website. Various drafts of website language, as well as informal discussion of the website's creation, were located in internal Philip Morris documents. I compared website statements pertaining to Philip Morris's stance on cigarette smoking and disease with statements made in tobacco trials. Results Philip Morris created and disseminated its website's message that it agreed that smoking causes disease and is addictive in an effort to sway public opinion, while maintaining in a litigation setting its former position that it cannot be proved that smoking causes disease or is addictive. Conclusions Philip Morris has not changed its position on smoking and health or addiction in the one arena where it has the most to lose—in the courtroom, under oath. PMID:18048599

  14. Comparison of the classically conditioned withdrawal reflex in cerebellar patients and healthy control subjects during stance: 2. Biomechanical characteristics.

    PubMed

    Kutz, D F; Kaulich, Th; Föhre, W; Gerwig, M; Timmann, D; Kolb, F P

    2014-03-01

    This study addresses cerebellar involvement in classically conditioned nociceptive lower limb withdrawal reflexes in standing humans. A preceding study compared electromyographic activities in leg muscles of eight patients with cerebellar disease (CBL) and eight age-matched controls (CTRL). The present study extends and completes that investigation by recording biomechanical signals from a strain-gauge-equipped platform during paired auditory conditioning stimuli (CS) and unconditioned stimuli (US) trials and during US-alone trials. The withdrawal reflex performance-lifting the stimulated limb (decreasing the vertical force from that leg, i.e. 'unloading') and transferring body weight to the supporting limb (increasing the vertical force from that leg, i.e. 'loading')-was quantified by the corresponding forces exerted onto the platform. The force changes were not simultaneous but occurred as a sequence of multiple force peaks at different times depending on the specific limb task (loading or unloading). Motor learning, expressed by the occurrence of conditioned responses (CR), is characterized by this sequence beginning already within the CSUS window. Loading and unloading were delayed and prolonged in CBL, resulting in incomplete rebalancing during the analysis period. Trajectory loops of the center of vertical pressure-derived from vertical forces-were also incomplete in CBL within the recording period. However, exposing CBL to a CS resulted in motor improvement reflected by shortening the time of rebalancing and by optimizing the trajectory loop. In summary, associative responses in CBL are not absent although they are less frequent and of smaller amplitude than in CTRL. PMID:24445111

  15. Balance failure in single limb stance due to ankle sprain injury: an analysis of center of pressure using the fractal dimension method.

    PubMed

    Doherty, Cailbhe; Bleakley, Chris; Hertel, Jay; Caulfield, Brian; Ryan, John; Delahunt, Eamonn

    2014-05-01

    Instrumented postural control analysis plays an important role in evaluating the effects of injury on dynamic stability during balance tasks, and is often conveyed with measures based on the displacement of the center-of-pressure (COP) assessed with a force platform. However, the desired outcome of the task is frequently characterized by a loss of dynamic stability, secondary to injury. Typically, these failed trials are discarded during research investigations, with the potential loss of informative data pertaining to task success. The novelty of the present study is that COP characteristics of failed trials in injured participants are compared to successful trial data in another injured group, and a control group of participants, using the fractal dimension (FD) method. Three groups of participants attempted a task of eyes closed single limb stance (SLS): twenty-nine participants with acute ankle sprain successfully completed the task on their non-injured limb (successful injury group); twenty eight participants with acute ankle sprain failed their attempt on their injured limb (failed injury group); sixteen participants with no current injury successfully completed the task on their non-dominant limb (successful non-injured group). Between trial analyses of these groups revealed significant differences in COP trajectory FD (successful injury group: 1.58±0.06; failed injury group: 1.54±0.07; successful non-injured group: 1.64±0.06) with a large effect size (0.27). These findings demonstrate that successful eyes-closed SLS is characterized by a larger FD of the COP path when compared to failed trials, and that injury causes a decrease in COP path FD. PMID:24746034

  16. A time-frequency approach to estimate critical time intervals in postural control.

    PubMed

    Zhang, Hongbo; Nussbaum, Maury A; Agnew, Michael J

    2015-11-01

    The critical time interval (CTI) is a parameter that has been used to distinguish open-loop from closed-loop control during upright stance. The aim of this study was to develop a new method to determine CTIs. The new approach, termed the intermittent critical time interval (ICTI) method, was motivated from evidence that upright standing is an intermittent rather than an asymptotic stability control process. For this ICTI method, center-of-pressure time series are first transformed to the time-frequency domain with a wavelet method. Subsequently, the CTI is assumed equal to the time span between two local maxima in the time-frequency domain within a distinct frequency band (i.e., 0.5-1.1 Hz). This new method may help facilitate better estimates of the transition time interval between open and closed-loop control during upright stance and can also be applied in future work such as in simulating postural control. In addition, this method can be used in future work to assess temporal changes in CTIs. PMID:25105745

  17. Precueing time but not direction of postural perturbation induces early muscular activation: comparison between young and elderly individuals.

    PubMed

    Silva, Marina Brito; Coelho, Daniel Boari; de Lima-Pardini, Andrea Cristina; Martinelli, Alessandra Rezende; Baptista, Thais da Silva; Ramos, Renato Teodoro; Teixeira, Luis Augusto

    2015-02-19

    In this study, we evaluated the effect of precueing characteristics of an impending perturbation to upright stance on reactive responses of distal leg muscles. Young and older individuals were compared in a task of recovering stable upright stance following rotation of the supporting platform to induce anterior or posterior body sway. Directions of the supporting platform rotation were randomized across trials. Immediately before postural perturbation participants were cued about direction and/or time of platform rotation, or performed the task under directional and temporal uncertainty of the impending perturbation. Results showed that precueing time of perturbation led to earlier muscular activation onset, while precueing perturbation direction did not modulate either latency or magnitude of muscular activation. Those effects were similar between age groups. Our findings suggest that awareness of the perturbation time favored shorter response latencies in both the young and older individuals. PMID:25562634

  18. The effect of short-duration sub-maximal cycling on balance in single-limb stance in patients with anterior cruciate ligament injury: a cross-sectional study

    PubMed Central

    Ageberg, Eva; Roberts, David; Holmström, Eva; Fridén, Thomas

    2004-01-01

    Background It has previously been shown that an anterior cruciate ligament (ACL) injury may lead to impaired postural control, and that the ability to maintain postural control is decreased by fatigue in healthy subjects. To our knowledge, no studies have reported the effect of fatigue on postural control in subjects with ACL injury. This study was aimed at examining the effect of fatigue on balance in single-limb stance in subjects with ACL injury, and to compare the effects, and the ability to maintain balance, with that of a control group of uninjured subjects. Methods Thirty-six patients with unilateral, non-operated, non-acute ACL injury, and 24 uninjured subjects were examined with stabilometry before (pre-exercise) and immediately after (post-exercise) short-duration, sub-maximal cycling. In addition, the post-exercise measurements were compared, to evaluate the instantaneous ability to maintain balance and any possible recovery. The amplitude and average speed of center of pressure movements were registered in the frontal and sagittal planes. The paired t-test was used for the intra-group comparisons, and the independent t-test for the inter-group comparisons, with Bonferroni correction for multiple comparisons. Results No differences were found in the effects of exercise between the patients and the controls. Analysis of the post-exercise measurements revealed greater effects or a tendency towards greater effects on the injured leg than in the control group. The average speed was lower among the patients than in the control group. Conclusions The results of the present study showed no differences in the effects of exercise between the patients and the controls. However, the patients seemed to react differently regarding ability to maintain balance in single-limb stance directly after exercise than the control group. The lower average speed among the patients may be an expression of different neuromuscular adaptive strategies than in uninjured subjects. PMID:15548328

  19. Effects of affective picture viewing on postural control

    PubMed Central

    Stins, John F; Beek, Peter J

    2007-01-01

    Background Emotion theory holds that unpleasant events prime withdrawal actions, whereas pleasant events prime approach actions. Recent studies have suggested that passive viewing of emotion eliciting images results in postural adjustments, which become manifest as changes in body center of pressure (COP) trajectories. From those studies it appears that posture is modulated most when viewing pictures with negative valence. The present experiment was conducted to test the hypothesis that pictures with negative valence have a greater impact on postural control than neutral or positive ones. Thirty-four healthy subjects passively viewed a series of emotion eliciting images, while standing either in a bipedal or unipedal stance on a force plate. The images were adopted from the International Affective Picture System (IAPS). We analysed mean and variability of the COP and the length of the associated sway path as a function of emotion. Results The mean position of the COP was unaffected by emotion, but unipedal stance resulted in overall greater body sway than bipedal stance. We found a modest effect of emotion on COP: viewing pictures of mutilation resulted in a smaller sway path, but only in unipedal stance. We obtained valence and arousal ratings of the images with an independent sample of viewers. These subjects rated the unpleasant images as significantly less pleasant than neutral images, and the pleasant images as significantly more pleasant than neutral images. However, the subjects rated the images as overall less pleasant and less arousing than viewers in a closely comparable American study, pointing to unknown differences in viewer characteristics. Conclusion Overall, viewing emotion eliciting images had little effect on body sway. Our finding of a reduction in sway path length when viewing pictures of mutilation was indicative of a freezing strategy, i.e. fear bradycardia. The results are consistent with current knowledge about the neuroanatomical organization of the emotion system and the neural control of behavior. PMID:17916245

  20. Time-Limited Psychotherapy With Adolescents

    PubMed Central

    Shefler, Gaby

    2000-01-01

    Short-term dynamic therapies, characterized by abbreviated lengths (10–40 sessions) and, in many cases, preset termination dates, have become more widespread in the past three decades. Short-term therapies are based on rapid psychodynamic diagnosis, a therapeutic focus, a rapidly formed therapeutic alliance, awareness of termination and separation processes, and the directive stance of the therapist. The emotional storm of adolescence, stemming from both developmental and psychopathological sources, leaves many adolescents in need of psychotherapy. Many adolescents in need of therapy resist long-term attachment and involvement in an ambiguous relationship, which they experience as a threat to their emerging sense of independence and separateness. Short-term dynamic therapy can be the treatment of choice for many adolescents because it minimizes these threats and is more responsive to their developmental needs. The article presents treatment and follow-up of a 17-year-old youth, using James Mann's time-limited psychotherapy method. PMID:10793128

  1. Time-limited psychotherapy with adolescents.

    PubMed

    Shefler, G

    2000-01-01

    Short-term dynamic therapies, characterized by abbreviated lengths (10-40 sessions) and, in many cases, preset termination dates, have become more widespread in the past three decades. Short-term therapies are based on rapid psychodynamic diagnosis, a therapeutic focus, a rapidly formed therapeutic alliance, awareness of termination and separation processes, and the directive stance of the therapist. The emotional storm of adolescence, stemming from both developmental and psychopathological sources, leaves many adolescents in need of psychotherapy. Many adolescents in need of therapy resist long-term attachment and involvement in an ambiguous relationship, which they experience as a threat to their emerging sense of independence and separateness. Short-term dynamic therapy can be the treatment of choice for many adolescents because it minimizes these threats and is more responsive to their developmental needs. The article presents treatment and follow-up of a 17-year-old youth, using James Mann's time-limited psychotherapy method. PMID:10793128

  2. Stance and the Subjunctive in Isleno Spanish

    ERIC Educational Resources Information Center

    Coles, Felice A.

    2012-01-01

    Isleno Spanish speakers maintain few contexts firmly in the subjunctive (for example, adverbial clauses with the conjunctions "para que" and "antes que" and nominal clauses with "querer"), with most other semantic or syntactic categories optionally licensing the subjunctive. This study will outline the obligatory and optional uses of present and…

  3. Asymmetric Sensory Reweighting in Human Upright Stance

    PubMed Central

    Logan, David; Kiemel, Tim; Jeka, John J.

    2014-01-01

    To investigate sensory reweighting as a fundamental property of sensor fusion during standing, we probed postural control with simultaneous rotations of the visual scene and surface of support. Nineteen subjects were presented with pseudo-random pitch rotations of visual scene and platform at the ankle to test for amplitude dependencies in the following conditions: low amplitude vision: high amplitude platform, low amplitude vision: low amplitude platform, and high amplitude vision: low amplitude platform. Gain and phase of frequency response functions (FRFs) to each stimulus were computed for two body sway angles and a single weighted EMG signal recorded from seven muscles. When platform stimulus amplitude was increased while visual stimulus amplitude remained constant, gain to vision increased, providing strong evidence for inter-modal reweighting between vision and somatosensation during standing. Intra-modal reweighting of vision was also observed as gains to vision decreased as visual stimulus amplitude increased. Such intra-modal and inter-modal amplitude dependent changes in gain were also observed in muscular activity. Gains of leg segment angle and muscular activity relative to the platform, on the other hand, showed only intra-modal reweighting. That is, changing platform motion amplitude altered the responses to both visual and support surface motion whereas changing visual scene motion amplitude did not significantly affect responses to support surface motion, indicating that the sensory integration scheme between somatosensation (at the support surface) and vision is asymmetric. PMID:24959665

  4. Time After Time

    NSDL National Science Digital Library

    National Security Agency Central Security Service

    2009-04-22

    Students use a variety of strategies and techniques to develop an understanding of telling time. They use estimation to tell time, using seconds, hours, and minutes in order to choose reasonable time estimates for given activities. Students use pictures, words, and symbols in order to read, write, and represent time to the nearest minute. Students determine elapsed time when given a start time, counting up using minutes and hours.

  5. Effects of 2 ankle destabilization devices on electromyography measures during functional exercises in individuals with chronic ankle instability.

    PubMed

    Donovan, Luke; Hart, Joseph M; Hertel, Jay

    2015-03-01

    Study Design Randomized crossover laboratory study. Objectives To determine the effects of ankle destabilization devices on surface electromyography (sEMG) measures of selected lower extremity muscles during functional exercises in participants with chronic ankle instability. Background Ankle destabilization devices are rehabilitation tools that can be worn as a boot or sandal to increase lower extremity muscle activation during walking in healthy individuals. However, they have not been tested in a population with pathology. Methods Fifteen adults with chronic ankle instability participated. Surface electromyography electrodes were located over the anterior tibialis, fibularis longus, lateral gastrocnemius, rectus femoris, biceps femoris, and gluteus medius. The activity level of these muscles was recorded in a single testing session during unipedal stance with eyes closed, the Star Excursion Balance Test, lateral hops, and treadmill walking. Each task was performed under 3 conditions: shod, ankle destabilization boot, and ankle destabilization sandal. Surface electromyography signal amplitudes were measured for each muscle during each exercise for all 3 conditions. Results Participants demonstrated a significant increase, with moderate to large effect sizes, in sEMG signal amplitude of the fibularis longus in the ankle destabilization boot and ankle destabilization sandal conditions during the unipedal eyes-closed balance test, the Star Excursion Balance Test in the anterior and posteromedial directions, lateral hops, and walking, when compared to the shod condition. Both devices also resulted in an increase in sEMG signal amplitudes, with large effect sizes of the lateral gastrocnemius, rectus femoris, biceps femoris, and gluteus medius during the unipedal-stance-with-eyes-closed test, compared to the shod condition. Conclusion Wearing ankle destabilization devices caused greater muscle activation during functional exercises in individuals with chronic ankle instability. Based on the magnitude of the effect, there were consistent increases in fibularis longus sEMG amplitudes during the unipedal eyes-closed balance test, the Star Excursion Balance Test in the anterior and posteromedial directions, and pre-initial contact and post-initial contact during lateral hops and walking. J Orthop Sports Phys Ther 2015;45(3):220-232. Epub 27 Jan 2015. doi:10.2519/jospt.2015.5222. PMID:25627150

  6. Martial Arts: Time Needed for Training

    PubMed Central

    Burke, David T.; Protopapas, Marina; Bonato, Paolo; Burke, John T.; Landrum, Rpbert F.

    2011-01-01

    Purpose To measure the time needed to teach a series of martial arts techniques to proficiency. Methods Fifteen volunteer subjects without any prior martial arts or self-defense experience were recruited. A panel of martial arts experts selected 21 different techniques including defensive stances, arm blocks, elbow strikes, palm strikes, thumbs to eyes, instep kicks and a carotid neck restraint. The critical elements of each technique were identified by the panel and incorporated into a teaching protocol, and then into a scoring system. Two black belt martial arts instructors directed a total of forty-five 45-minute training sessions. Videotaped proficiency testing was performed weekly. The videotapes were reviewed by the investigators to determine the proficiency levels of each subject for each technique. Results The techniques were rated by the average number of training sessions needed for an individual to develop proficiency in that technique. The mean number of sessions necessary to train individuals to proficiency ranged from 27 to 38.3. Using this system, the most difficult techniques seemed to be elbow strikes to the rear, striking with thumbs to the eyes and arm blocking. Conclusions In this study 29 hours of training was necessary to train novice students to be proficient in 21 offensive and defensive martial arts techniques. To our knowledge, this is the first study that attempts to measure the learning curves involved when teaching martial arts techniques. PMID:22375215

  7. Telling Time

    NSDL National Science Digital Library

    Ms. Berman

    2008-11-12

    Lets practice telling time! Practice with the dragon to tell time. Dragon Telling Time How long does it take you to tell time?Stop the Clock! Can you set the correct time? Try it here! Setting the correct time ...

  8. Telling Time

    NSDL National Science Digital Library

    Miss Lerdahl

    2010-01-26

    Practice telling time with these fun games and activities! Match the time on the clocks with this game! Match the clocks game! Primary Games Match the Clocks Tell time with a dragon. Stop the clock! Make the right time! Time to the Hour Quiz Time Test Time to the Minute Quiz Practice telling what time it will be later. Elapsed Time Work on Elapsed Time Test your skills with the Matching Elapsed Time Game ...

  9. Black time … white time: My time … your time

    Microsoft Academic Search

    Yalmambirra

    2000-01-01

    Indigenous time began with the Era of Creation. White time began with the invention of the calendar, sundial and clock. White time was, and still is, influenced by the calendar, clock or watch. Time to go to sleep, time to get up, time to go to work...go home, time for dinner and time to watch the football or cricket. Even

  10. Telling Time

    NSDL National Science Digital Library

    Mrs. Fiefia

    2010-03-23

    Practice telling time with these fun games and activities! Match the time on the clocks with this game! Match the clocks game! Tell time with a dragon. Stop the clock! Practice telling what time it will be later. Elapsed Time ...

  11. Telling Time

    NSDL National Science Digital Library

    Mr. Udy

    2006-11-14

    Students - These games will help you practice telling time and calculating time measurements. Students practice telling time from an analog clock. Play this game to figure out What time is it? Play this game at least 15 times, then come back and play another clock game. Students practice your telling time skills by clicking here. In this game you determine What time will it be?. Play this game at least 10 times. After ...

  12. TIME MANAGEMENT Time Management Questionnaire

    E-print Network

    = ____ Number of hours for meals/snacks (including preparation/clean-up time) ____ x 7 = ____ Travel time of hours for meals/snacks (including preparation/clean-up time) 3 x 7 = 21 Travel time to and from campus 1

  13. Elapsed Time

    NSDL National Science Digital Library

    2010-01-01

    In this activity, students are shown three clocks, one with a starting time, one an ending time, and the third has the current time. At first the current time is the same as the start time and the students advance the current time by either one hour, five minutes, or one minute until they get to the end time. The applet keeps track of how much total time has elapsed. The student can also switch to guess mode where they are given a start time and end time and have to guess the amount of elapsed time between them. This activity allows students to practice reading clocks and finding how much time has elapsed between two times. This activity includes supplemental materials, including background information about the topics covered, a description of how to use the application, and exploration questions for use with the java applet.

  14. Universal Time

    NSDL National Science Digital Library

    This article explains the concept of 'Universal Time' (UT), sometimes referred to as 'Coordinated Universal Time' (UTC). Topics include how UTC is measured, who uses it, and a brief discussion of the historical context of this time standard.

  15. Time Out for Time Management.

    ERIC Educational Resources Information Center

    Herr, Judy; And Others

    1995-01-01

    Discusses time management skills, noting that effective time management entails awareness of such things as how we use time and when our mental energy peaks and falls. Offers time management suggestions for day-care administrators such as developing a realistic "to-do" list, scheduling uninterrupted time to engage in important tasks, and limiting…

  16. Reinventing Time

    ERIC Educational Resources Information Center

    Technology Teacher, 2004

    2004-01-01

    What do planet Earth, a swinging pendulum, a quartz crystal, and a Cesium atom have in common? They have all been used by humans to measure time. They represent humanity's progress through time in measuring time itself. But what is it, really, that humans set out to measure? Before time could be measured, somebody had to decide what to actually…

  17. Virtual time

    Microsoft Academic Search

    David R. Jefferson

    1985-01-01

    Virtual time is a new paradigm for organizing and synchronizing distributed systems which can be applied to such problems as distributed discrete event simulation and distributed database concurrency control. Virtual time provides a flexible abstraction of real time in much the same way that virtual memory provides an abstraction of real memory. It is implemented using the Time Warp mechanism,

  18. Universal Time

    NSDL National Science Digital Library

    2012-08-03

    This is a lesson plan for an activity that explores time zone math. Learners will translate their local time to times in other zones around the world and work with the concept of Universal Time, specifically in reference to the reporting, description and analysis of solar flares and coronal mass ejections. This is activity 10 from Exploring Magnetism Guide 3: Magnetic Mysteries of the Aurora educator guide.

  19. Time Honoured

    ERIC Educational Resources Information Center

    Campbell, Mora; Timmerman, Peter

    2007-01-01

    The vast majority of literature and practices in environmental education focuses on places and spaces. Little attention has been paid to time and temporalities as elements of environments, and the ways in which how we experience time affects our experience of place. This paper is an examination of the ways in which reflection on time can be…

  20. Making Time

    ERIC Educational Resources Information Center

    Gorham, Gail; Bobis, Janette

    2005-01-01

    This article presents several tips that teachers can use to teach children about time. One activity, investigating 24-hour time, aims to familiarise upper primary students with converting a.m. and p.m. notations to 24-hour time. Another activity requires students to construct a calendar month in order to familiarize themselves with the components…

  1. Sequencing Time

    NSDL National Science Digital Library

    2007-12-12

    In this activity, students gain an understanding of relative and numerical time by placing events in sequence and assigning relative times to the events. This will familarize them with the methods used by scientists to develop the geologic time scale. This activity contains objectives, materials, procedure, and extensions.

  2. Reaction Time

    NSDL National Science Digital Library

    2012-06-26

    In this activity, learners explore reaction time and challenge themselves to improve their coordination. Do you want to move faster? Catch that ball that you never seem to see in time? Use a simple test to help you improve your reaction (or response) time.

  3. Modelling Time

    E-print Network

    Burra G. Sidharth

    2008-09-03

    We briefly review two concepts of time - the usual time associated with "being" and more recent ideas, answering to the description of "becoming". The approximation involved in the former is examined. Finally we argue that it is (unpredictable) fluctuations that underlie time.

  4. Genu recurvatum in cerebral palsy--part A: influence of dynamic and fixed equinus deformity on the timing of knee recurvatum in children with cerebral palsy.

    PubMed

    Svehlík, Martin; Zwick, Ernst B; Steinwender, Gerhardt; Saraph, Vinay; Linhart, Wolfgang E

    2010-07-01

    The aim of the study was to confirm the hypothesis of the influence of the dynamic and fixed equinus deformity on the timing of knee recurvation (hyperextension). According to our hypothesis, dynamic equinus is linked to early and fixed equinus and to late knee hyperextension. A group 35 children with cerebral palsy (47 lower limbs) was divided into two subgroups according to the timing of maximum knee hyperextension. Clinical examination confirmed our hypothesis. Gait analysis and musculoskeletal modelling results were compared with 12 normally developing children. Both recurvatum groups had forefoot landing and neither achieved normal ankle dorsiflexion. Electromyographic examination revealed an abnormally high soleus activity in a single stance. Muscle length changes of medial gastrocnemius and soleus were in agreement with our hypothesis. Such a finding might simplify the decision as to which treatment to select for equinus deformity, present in patients with genu recurvatum. PMID:20442674

  5. Quantum Time

    E-print Network

    John Ashmead

    2010-05-05

    Normally we quantize along the space dimensions but treat time classically. But from relativity we expect a high level of symmetry between time and space. What happens if we quantize time using the same rules we use to quantize space? To do this, we generalize the paths in the Feynman path integral to include paths that vary in time as well as in space. We use Morlet wavelet decomposition to ensure convergence and normalization of the path integrals. We derive the Schr\\"odinger equation in four dimensions from the short time limit of the path integral expression. We verify that we recover standard quantum theory in the non-relativistic, semi-classical, and long time limits. Quantum time is an experiment factory: most foundational experiments in quantum mechanics can be modified in a way that makes them tests of quantum time. We look at single and double slits in time, scattering by time-varying electric and magnetic fields, and the Aharonov-Bohm effect in time.

  6. Time Machine

    NSDL National Science Digital Library

    Larry Flammer

    In this lesson students will experience how geological and biological events have occurred in a clear sequence of vast but measured time. Students are taken on a simulated voyage backward in time, to the beginning of our planet. They witness that beginning, the origin of life, and a number of key events leading to the present. This becomes a dramatic experience, involving body and mind, helping students to relate physically at least to the relative timing of events in geological and biological history, if not to the absolute vastness of that time.

  7. Geologic Time

    NSDL National Science Digital Library

    William L. Newman

    1997-01-01

    The Earth is very old -- 4.5 billion years or more -- according to recent estimates. This vast span of time, called geologic time by earth scientists, is difficult to comprehend in the familiar time units of months and years, or even centuries. How then do scientists reckon geologic time, and why do they believe the Earth is so old? A great part of the secret of the Earth's age is locked up in its rocks, and our centuries-old search for the key led to the beginning and nourished the growth of geologic science.

  8. Human Genetic Engineering: A Survey of Student Value Stances

    ERIC Educational Resources Information Center

    Wilson, Sara McCormack; And Others

    1975-01-01

    Assesses the values of high school and college students relative to human genetic engineering and recommends that biology educators explore instructional strategies merging human genetic information with value clarification techniques. (LS)

  9. APPS's stance on self-plagiarism: Just say no.

    PubMed

    Culley, Theresa M

    2014-07-01

    Should authors be able to reuse the same text in multiple papers without citing the earlier source? Known as self-plagiarism, this practice is strongly discouraged in Applications in Plant Sciences (APPS) because it violates professional standards, is potentially deceptive, and lacks originality. The most frequent form of self-plagiarism in APPS submissions is text recycling, which depending on the extent and location of copied text, has consequences ranging from authors being required to rewrite duplicated text or add citations, to automatic rejection of a manuscript without review. Ultimately, avoidance of self-plagiarism will result in original articles that improve upon, and do not simply replicate, the existing literature. PMID:25202643

  10. Comparison of human and humanoid robot control of upright stance

    Microsoft Academic Search

    Robert J. Peterka

    2009-01-01

    There is considerable recent interest in developing humanoid robots. An important substrate for many motor actions in both humans and biped robots is the ability to maintain a statically or dynamically stable posture. Given the success of the human design, one would expect there are lessons to be learned in formulating a postural control mechanism for robots. In this study

  11. Investigating Asynchronous Online Communication: A Connected Stance Revealed

    ERIC Educational Resources Information Center

    Wegmann, Susan J.; McCauley, Joyce K.

    2014-01-01

    This research project explores the effects of altering the structure of discussion board formats to increase students' engagement and participation. This paper will present the findings of a two-university, two-class research project in which asynchronous discussion board entries were analyzed for substance. By using oral discourse analysis…

  12. [Nursing stance in the face of Jinn possession in Mayotte].

    PubMed

    Gillard-Berthod, Claire

    2013-01-01

    Caregivers and nursing students practising in Mayotte can find themselves in a difficult position when faced with patients believing themselves to be possessed by spirits called Jinn. Through a multidisciplinary roundtable, different perspectives and practices can be shared leading to a more enlightened treatment of patients which respects their beliefs, blending traditional and modern medicine. PMID:24245404

  13. Place-based education: a transformative activist stance

    NASA Astrophysics Data System (ADS)

    Coughlin, Christine A.; Kirch, Susan A.

    2010-12-01

    The ethnography presented by van Eijck and Roth focuses on the activities of people involved in a government funded internship program in conservation and restoration, which was offered by a `multidisciplinary research center' through a local First Nation adult education center. The internship was designed, in partnership with a local non-profit conservation society (OceanHealth), to appeal to First Nation men and women considering career change, returning to school, or re-entering the work place. The primary aim of the internship was to `provide authentic science for diverse student populations (and their teachers), with particular attention to the needs of students from First Nations, to become scientifically literate to the extent that it prepares them for participating in public debates, community decision-making, and personal living consistent with long-term environmentally sustainable forms of life'. The authors report that at least one of the two interns was not interested in science and a WSÁNEC elder expressed dissatisfaction with the efforts to establish the nature park and its current approved uses. Van Eijck and Roth argue that the divergence between the project aims and the goals of the participants are a result of how `place' is viewed in place-based education and that disagreements like these can be resolved if place is theorized as chronotope. There are many interesting ideas raised and directions taken in the article by van Eijck and Roth. After several discussions during the review process, we decided to focus our forum response on the meaning of `place' in place-based education, the utility of theorizing place as a chronotope, the implications for teaching-learning (`education'), and musings on what remains unclear.

  14. Place-Based Education: A Transformative Activist Stance

    ERIC Educational Resources Information Center

    Coughlin, Christine A.; Kirch, Susan A.

    2010-01-01

    The ethnography presented by van Eijck and Roth focuses on the activities of people involved in a government funded internship program in conservation and restoration, which was offered by a "multidisciplinary research center" through a local First Nation adult education center. The internship was designed, in partnership with a local non-profit…

  15. Pleasure, Learning, Video Games, and Life: The Projective Stance

    ERIC Educational Resources Information Center

    Gee, James Paul

    2005-01-01

    This article addresses three questions. First, what is the deep pleasure that humans take from video games? Second, what is the relationship between video games and real life? Third, what do the answers to these questions have to do with learning? Good commercial video games are deep technologies for recruiting learning as a form of profound…

  16. A Rhetorical Stance on the Archives of Civic Action.

    ERIC Educational Resources Information Center

    Miller, Thomas P.; Bowdon, Melody

    1999-01-01

    Contextualizes the rhetorical archive and moves beyond composition to the traditions of civic discourse, classical rhetorical theory, and moral philosophy. Wonders what kind of archive of actual historical practices would enable rhetoricians to confirm or qualify the existence of a genuine tradition of civic discourse. (RS)

  17. Links between Parents' Epistemological Stance and Children's Evidence Talk

    ERIC Educational Resources Information Center

    Luce, Megan R.; Callanan, Maureen A.; Smilovic, Sarah

    2013-01-01

    Recent experimental research highlights young children's selectivity in learning from others. Little is known, however, about the patterns of information that children actually encounter in conversations with adults. This study investigated variation in parents' tendency to focus on testable evidence as a way to answer science-related questions…

  18. The Adaptationist Stance and Evolutionary Computation Mark Jelasity

    E-print Network

    Jelasity, Márk

    subsystem such as a food chain to be our organism. P4 (one niche): Beside P2 it is also necessary as in biology and this application may have significant benefits. It will also be shown that this approach has the following principles in order to be applicable: P1 (separation): The separation of the organism under in

  19. Dialogic Teaching: Talk in Service of a Dialogic Stance

    ERIC Educational Resources Information Center

    Boyd, Maureen Patricia; Markarian, William C.

    2011-01-01

    We consider what it means to be a dialogic teacher as characterized by Paulo Freire and Robin Alexander, and utilizing discourse analysis, we explicate how one elementary teacher's talk reflects these characteristics. We provide context for and analysis of a seven-minute discussion selected as a cumulative achievement the focal nine-year-olds are…

  20. Reasons Given by UK Churchgoers for Their Stance on Evolution

    ERIC Educational Resources Information Center

    Village, Andrew; Baker, Sylvia

    2013-01-01

    A sample of 661 churchgoers from a range of Christian denominations in the United Kingdom was asked about Darwinian evolution (defined as the common origin of all species, including humans). Respondents were categorised as those who accepted the idea, those who rejected it, and those who were unsure or neutral. People in each category were given a…

  1. Time Management

    ERIC Educational Resources Information Center

    Stoilov, Todor, Ed.

    2012-01-01

    The time management is worthy goal of many human activities. It concerns variety problems related to goals definition, assessment of available resources, control of management policies, scheduling of decisions. This book is an attempt to illustrate the decision making process in time management for different success stories, which can be used as…

  2. Geological Time

    NSDL National Science Digital Library

    "Why do engineers need to know about geologic time?" That question is answered in this resource from the University of Saskatchewan's Department of Civil and Geological Engineering. Provided here is a discussion of the concepts of geological time; relative dating methods, such as correlation; and absolute dating methods, such as radiometric methods. Diagrams and charts are included to demonstrate these complex concepts.

  3. Virtual Time

    Microsoft Academic Search

    David Jefferson

    1983-01-01

    Virtual time is a broad, new paradigm for organizing and synchronizing distributed systems, subsuming such heretofore distantly related problems as distributed discrete event simulation and distributed database concurrency control. It is an abstraction of real time in much the same way that virtual memory is an abstraction of real memory, and it reorganizes the concepts of concurrency and synchronization in

  4. Elapsed Time

    NSDL National Science Digital Library

    2011-05-24

    This lesson is designed to develop students' ability to find elapsed time given starting and ending times. This lesson provides links to discussions and activities related to the topic as well as suggested ways to integrate them into the lesson. Finally, the lesson provides links to follow-up lessons designed for use in succession with the current one.

  5. Managing Time.

    ERIC Educational Resources Information Center

    Murphy, Linda; Della Corte, Suzanne

    1991-01-01

    This newsletter issue discusses time management techniques for parents of special needs children. Techniques include changing one's attitudes about perfection, prioritizing tasks, having a back-up plan, learning to say "no," asking for help, keeping things simple, hiring others, using waiting time wisely, and doing two things at once. Household…

  6. Screen Time

    NSDL National Science Digital Library

    2012-06-26

    This game asks you a series of questions about how much time you spend in front of a screen, not being active. It begins by pointing out that since we spend a lot of time in front of computer screens at work or school, additional time at home can really affect how healthy we are. It asks how much time you spend watching TV, playing computer games, and using the computer each day. It then adds up the total amount of screen time you spend every day, and calculates how many hours you spend a year in front of a screen. It also tells you if that's a healthy amount, and suggests ways to stay active while in front of screens.

  7. Finding time.

    PubMed

    Killeen, Peter R

    2014-01-01

    We understand time through our models of it. These are typically models of our physical chronometers, which we then project into our subjects. A few of these models of the nature of time and its effects on the behavior of organisms are reviewed. New models, such as thermodynamics and spectral decomposition, are recommended for the potential insights that they afford. In all cases, associations are essential features of timing. To make them, time must be discretized by stimuli such as hours, minutes, conditioned stimuli, trials, and contexts in general. Any one association is seldom completely dominant, but rather shares control through proximity in a multidimensional space, important dimensions of which may include physical space and time as rendered by Fourier transforms. PMID:23973706

  8. Time Clocks

    NSDL National Science Digital Library

    Stephen Greb

    This exercise can be used to demonstrate changes in the Earth through time, and the length of time it took for those changes to take place. A list of Important Dates in Earth History is provided that contains the dates of the events shown on a time clock. The teacher can pick events from the list of key events and calculate (or have students calculate) the time for the key events they wish to use. A page-size image of the clock can be printed and turned into an overhead transparency. To better demonstrate the changes since the beginning of the Paleozoic Era, the same exercise could be done the second day of class, using only the last 570 million years of time.

  9. Time ephemeris

    NASA Astrophysics Data System (ADS)

    Fukushima, T.

    1995-02-01

    The location-independent part of barycentric coordinate time and geocentric coordinate time (TCB-TCG), the difference between the two new time scales adopted by the IAU, was integrated numerically for three JPL planetary/lunar ephemerides; DE102, DE200, and DE245. The differences among these three integrations were mostly explained by the difference in the adopted constants of the ephemerides. It was shown that the post-Newtonian correction and the perturbation by asteroids are negligible except for the mean rate, LC. The comparison of these numerical integrations with the analytical formulas of Hirayama et al. (1987) and Fairhead & Bretagnon (1990) as well as their extended versions lead to the best estimate of LC as 1.480 826 845 7 x 10-8 + or - 1.0 x 10-17. Combining this with the recent value of the geoid potential in Bursa et al. (1992), we estimate the value of LB, the scale difference between TCB and terrestrial time (TT), as 1.550 519 748 x 10-8 + or - 4 x 10-17. This will be useful in converting the numerical values of some astronomical constants determined in the old IAU time scale barycentric dynamic time (TDB) to those in TCB. Also the paper will be useful when converting between TCB and TDB, i.e. the time scales themselves.

  10. On Time

    NSDL National Science Digital Library

    This online exhibit from a prominent American museum explores the character of time -- its impact on our daily lives and its ability to shape and reform human consciousness. The site is from the National Museum of American History and concentrates on how humans have measured time from 1700 to the present. The exhibit presents text and images describing the history of keeping time from the century immediately preceding the industrial revolution -- when sundials were still in use -- to our present age of digital access and a global village that never sleeps.

  11. Thrombin Time

    MedlinePLUS

    ... 1. Can the thrombin time be performed in my doctor's office? With the exception of a PT ... DC. Pp 227-238. Henry's Clinical Diagnosis and Management by Laboratory Methods. 21st ed. McPherson R, Pincus ...

  12. Creative Time

    NSDL National Science Digital Library

    2012-08-31

    Creative Time curates, funds, and organizes public art projects, so their website is a reference of the form dating back to 1975. You can browse by program name, date or artist's name (the most common of these being "multiple artists.") Creative Time's roster also includes familiar names such as Marina Abramovic, Doug Aitken, Laurie Anderson, David Byrne, Paul Chan, Jenny Holzer, Gary Hume, Vik Muniz, Takashi Murakami, Shirin Neshat, Steve Powers, and Cai Guo-Qiang. For example, Creative Time worked with Cai Guo-Qiang to present Light Cycle, in 2003, to celebrate the 150th anniversary of New York City's Central Park; in 2008 David Byrne's Playing the Building transformed the Battery Maritime Building in Lower Manhattan into a massive sound sculpture that visitors could play using a keyboard; and in summer 2012 Creative Time and multiple artists hosted a sandcastle competition at Far Rockaway, possibly the start of a new New York summer tradition.

  13. Bleeding time

    MedlinePLUS

    Bleeding time is a blood test that looks at how fast small blood vessels in the skin close to stop you from bleeding. ... deep enough to cause a tiny amount of bleeding. The blood pressure cuff is immediately deflated. Blotting ...

  14. Time Management

    NSDL National Science Digital Library

    MindTools (MindTools)

    2012-01-20

    This section of Mind Tools teaches you time management skills. These are the simple, practical techniques that have helped the leading people in business, sport and public service reach the pinnacles of their careers.

  15. Time outs

    MedlinePLUS

    ... Time-out technique for discipline. Children's Health Network web site. http://www.childrenshealthnetwork.org/CRS/CRS/pa_ ... a break from negative behavior. Massachusetts Medical Society web site. http://www.massmed.org/patient-care/health- ...

  16. Wuda Time

    NSDL National Science Digital Library

    The Wuda Time project management tool is designed to help individuals keep track of their dedication to various tasks and operations. Visitors can sign up right on the site to have instant access to this powerful tool. It's easy to use and users can prioritize certain tasks with a color-coded system or designate certain task completion times. This version is compatible with all operating systems.

  17. About time

    NASA Technical Reports Server (NTRS)

    Denning, Peter J.

    1990-01-01

    Time has historically been a measure of progress of recurrent physical processes. Coordination of future actions, prediction of future events, and assigning order to events are three practical reasons for implementing clocks and signalling mechanisms. In large networks of computers, these needs lead to the problem of synchronizing the clocks throughout the network. Recent methods allow this to be done in large networks with precision around 1 millisecond despite mean message exchange times near 5 milliseconds. These methods are discussed.

  18. Computation method for available response time due to tripping at minimum foot clearance.

    PubMed

    Nagano, H; Begg, R; Sparrow, W A

    2013-01-01

    Falls prevention is important for older individuals to maintain healthy lifestyles and is an essential challenge in sustaining the socioeconomic structure of many advanced nations. Tripping has been recognized as the largest cause of falls and accordingly, understanding tripping-induced anterior balance loss is necessary in reducing the overall frequency of falls among older adults. Hazardous anterior balance loss due to tripping can be attributed to the mid-swing phase event, minimum foot clearance (MFC). The mechanism of tripping-induced anterior balance loss can be described as anterior movement of the center of mass (CoM) passing the frontal boundary of the supporting base between the swing and stance toes. The first aim of the current study was to establish a computational method for determining available response time (ART) to anterior balance loss due to tripping at MFC, in other words, the time taken for CoM to reach the anterior boundary and therefore, the time limit for balance recovery. Kinematic information of CoM and both toes in addition to simulated impact force due to tripping at MFC were used to estimate ART. The second aim was to apply correlation analysis to a range of gait parameters to identify the factors influencing ART. ART for balance loss in the forward direction due to tripping was on average. 0.11s for both the dominant and non-dominant limbs' simulated tripping at MFC. Correlation analysis revealed five factors at MFC that prolong ART including: 1) greater fore-aft distance from CoM to stance toe, 2) greater sideway distance from CoM to swing toe, 3) longer distance from CoM to the frontal boundary of the supporting base, 4) slower CoM forward velocity and 5) slower horizontal toe velocity. The established ART computation method can be utilized to examine the effects of ageing and various gait tasks on the likelihood of tripping-induced anterior balance loss and associated falls. PMID:24110833

  19. Time 100

    NSDL National Science Digital Library

    1998-01-01

    This Time Warner Pathfinder (discussed in the November 11, 1994 Scout Report) Time Magazine site, released to coincide with a Time cover story of the same title, is the first in what is to be a five part site that will eventually cover 100 of the 20th Century's most influential people. At present the site contains profiles of 20 of the century's most influential "leaders & revolutionaries," including Margaret Sanger, Vladimir Lenin, Winston Churchill, Dr. Martin Luther King, Jr., Ayatolla Ruholla Khomeini, and the anonymous Chinese protester who blocked the tank in the Tienanmen Square protest in 1989. Stories about the personalities by such authors as Gloria Steinem, Arthur Schlesinger, Jr., Salman Rushdie, Elie Wiesel, and Stanley Karnow, among others, highlight the site. There is also a timeline of each personality, as well as a timeline of the century. For the personalities who were covered by Time, an original in-depth story from the Time archives is available. Forthcoming throughout 1998 and 1999 are sections on "entertainers & artists, builders & titans, scientists & thinkers, and heroes and inspirations." The site is also available in a Shockwave Flash version.

  20. Geologic Time

    NSDL National Science Digital Library

    Timothy Heaton

    This site contains 24 questions on the topic of geologic time, which covers dating techniques and unconformities. This is part of the Principles of Earth Science course at the University of South Dakota. Users submit their answers and are provided immediate feedback.

  1. Reaction Time

    NSDL National Science Digital Library

    Michael Horton

    2009-05-30

    This lab is not an inquiry activity. There are some students whose reaction times will not allow them to catch a 12 inch ruler. They may use a dowel, stick, strip of cardboard, etc. Although the students are led to believe that the point of the lab is to

  2. Reaction Time

    NSDL National Science Digital Library

    WGBH Boston

    2003-01-01

    In this activity, learners conduct an experiment to test how fast they can react. Learners try to catch a piece of paper with a ruler printed on it (or a ruler) as quickly as they can. Learners collect data and compare the reaction times of friends and family.

  3. Deep Time

    NSDL National Science Digital Library

    2010-04-30

    In this video a Penn State professor refers to National Park canyons carved out by water and wind as he explains “deep time” - the notion that the earth is billions of years old; another professor states how the theory of evolution is supported by evidence of an ancient Earth recorded in rocks.

  4. Wasted time.

    PubMed

    Newnham, David

    2015-03-18

    My schedule is tight. I must get to the supermarket and back in time to leave for work, so the last thing I need is a car on its side around the next bend. But there it is, smoke rising from the engine and a passer-by fighting a jammed door. 'Driver's trapped,' he shouts. 'You got a mobile?' PMID:25783260

  5. Time Remains

    E-print Network

    Sean Gryb; Karim Thebault

    2014-08-12

    On one popular view, the general covariance of gravity implies that change is relational in a strong sense, such that all it is for a physical degree of freedom to change is for it to vary with regard to a second physical degree of freedom. At a quantum level, this view of "change as relative variation" leads to a "fundamentally timeless" formalism for quantum gravity. Here, we will show how one may avoid this acute `problem of time'. Under our view, duration is still regarded as relative, but temporal succession is taken to be absolute. Following our approach, which is presented in more formal terms in arXiv:1303.7139, it is possible to conceive of a genuinely dynamical theory of quantum gravity within which time, in a substantive sense, remains.

  6. Pendulum Time

    NSDL National Science Digital Library

    IEEE

    2014-03-10

    In this activity, learners explore how the pendulum has been a reliable way to keep time for centuries. Learners work in teams to build their own working clock using a pendulum out of everyday materials. Learners will need to be able to speed up and slow down the motion of the pendulum clock. They sketch their plans, consider what materials they will need, build the clock, test it, and present reflections to their group.

  7. Female Team Overall Name Age Rank Time Rank Time Rank Time Pace Rank Time Rank Time Pace Time

    E-print Network

    Suzuki, Masatsugu

    Female Team Overall Name Age Rank Time Rank Time Rank Time Pace Rank Time Rank Time Pace Time 1 Amy:56:27.6 Deborah Mc Eligot Deborah Storrings Male Team Overall Name Age Rank Time Rank Time Rank Time Pace Rank Time Rank Time Pace Time 1 Macon Fessenden 20 1 5:42.2 2 0:26.9 1 34:29.7 3:23 1 0:12.8 1 17:41.1 3

  8. No Time for Time Out.

    ERIC Educational Resources Information Center

    Hannon, Jean

    2002-01-01

    Young students can benefit when teachers address behavior in positive, rather than punitive, ways. This paper describes how one teacher stopped using punitive time outs and instead developed a program in which working together on learning and having class responsibilities was meaningful enough that instances of troublesome behavior would be…

  9. Evidence for a Time-Invariant Phase Variable in Human Ankle Control

    PubMed Central

    Gregg, Robert D.; Rouse, Elliott J.; Hargrove, Levi J.; Sensinger, Jonathon W.

    2014-01-01

    Human locomotion is a rhythmic task in which patterns of muscle activity are modulated by state-dependent feedback to accommodate perturbations. Two popular theories have been proposed for the underlying embodiment of phase in the human pattern generator: a time-dependent internal representation or a time-invariant feedback representation (i.e., reflex mechanisms). In either case the neuromuscular system must update or represent the phase of locomotor patterns based on the system state, which can include measurements of hundreds of variables. However, a much simpler representation of phase has emerged in recent designs for legged robots, which control joint patterns as functions of a single monotonic mechanical variable, termed a phase variable. We propose that human joint patterns may similarly depend on a physical phase variable, specifically the heel-to-toe movement of the Center of Pressure under the foot. We found that when the ankle is unexpectedly rotated to a position it would have encountered later in the step, the Center of Pressure also shifts forward to the corresponding later position, and the remaining portion of the gait pattern ensues. This phase shift suggests that the progression of the stance ankle is controlled by a biomechanical phase variable, motivating future investigations of phase variables in human locomotor control. PMID:24558485

  10. Evidence for a time-invariant phase variable in human ankle control.

    PubMed

    Gregg, Robert D; Rouse, Elliott J; Hargrove, Levi J; Sensinger, Jonathon W

    2014-01-01

    Human locomotion is a rhythmic task in which patterns of muscle activity are modulated by state-dependent feedback to accommodate perturbations. Two popular theories have been proposed for the underlying embodiment of phase in the human pattern generator: a time-dependent internal representation or a time-invariant feedback representation (i.e., reflex mechanisms). In either case the neuromuscular system must update or represent the phase of locomotor patterns based on the system state, which can include measurements of hundreds of variables. However, a much simpler representation of phase has emerged in recent designs for legged robots, which control joint patterns as functions of a single monotonic mechanical variable, termed a phase variable. We propose that human joint patterns may similarly depend on a physical phase variable, specifically the heel-to-toe movement of the Center of Pressure under the foot. We found that when the ankle is unexpectedly rotated to a position it would have encountered later in the step, the Center of Pressure also shifts forward to the corresponding later position, and the remaining portion of the gait pattern ensues. This phase shift suggests that the progression of the stance ankle is controlled by a biomechanical phase variable, motivating future investigations of phase variables in human locomotor control. PMID:24558485

  11. BAD Times

    NSDL National Science Digital Library

    The Black Americans for Democracy (BAD) Times started publication in 1971, growing out of the activist efforts and movement started in the late 1960s on the campus of the University of Arkansas. The BAD organization started life in 1970 in the old student union building on campus, and became well known for their activism and calls for greater integration of student life, university programs, and athletics. The newspaper can claim at least one student who became very well-known, the author E. (Everett) Lynn Harris, who was the BAD treasurer. This digital collection offers interested parties access to twenty issues of newspapers published by the group from 1971 to 1977. Visitors can make their way through the issues here, and they can search by keyword as well.

  12. A robust real-time gait event detection using wireless gyroscope and its application on normal and altered gaits.

    PubMed

    Gouwanda, Darwin; Gopalai, Alpha Agape

    2015-02-01

    Gait events detection allows clinicians and biomechanics researchers to determine timing of gait events, to estimate duration of stance phase and swing phase and to segment gait data. It also aids biomedical engineers to improve the design of orthoses and FES (functional electrical stimulation) systems. In recent years, researchers have resorted to using gyroscopes to determine heel-strike (HS) and toe-off (TO) events in gait cycles. However, these methods are subjected to significant delays when implemented in real-time gait monitoring devices, orthoses, and FES systems. Therefore, the work presented in this paper proposes a method that addresses these delays, to ensure real-time gait event detection. The proposed algorithm combines the use of heuristics and zero-crossing method to identify HS and TO. Experiments involving: (1) normal walking; (2) walking with knee brace; and (3) walking with ankle brace for overground walking and treadmill walking were designed to verify and validate the identified HS and TO. The performance of the proposed method was compared against the established gait detection algorithms. It was observed that the proposed method produced detection rate that was comparable to earlier reported methods and recorded reduced time delays, at an average of 100 ms. PMID:25619613

  13. Cosmic Times

    NSDL National Science Digital Library

    2012-08-03

    This series of curriculum support materials and classroom activities explores how our understanding of the nature of the universe has changed during the past 100 years. Students examine the process of science through the stories of the people and the discoveries that caused our understanding to evolve from a static universe to a universe whose expansion is accelerating. The series illustrates the nature of science by tracing the process of discovery from the confirmation of Einstein's theory of gravity, to Hubble's evidence for the expanding universe, to the detection of the microwave background, and finally to the discovery of dark energy. The series includes six posters, each resembling the front page of a newspaper from a particular time in this history with articles describing the discoveries. Each poster is accompanied by an online teacher guide and 4-5 downloadable, inquiry-based lessons. Downloadable newsletter versions of the poster are available for individual student use, with three editions for different reading levels (Early Edition for 7-8 grade readers, Home Edition for 9-10 grade readers, and Late Edition for 11-12 grade readers). Lesson plans can be found by following the link from Teacher Resources to Curriculum Tools to Sortable Table of the Lessons.

  14. Doing Time

    PubMed Central

    Yang, Suzanne; Kadouri, Alane; Révah-Lévy, Anne; Mulvey, Edward P.; Falissard, Bruno

    2009-01-01

    Once convicted, the perpetrator of serious crime embarks upon a new journey: the challenge of adjusting to long-term imprisonment. Prisoners’ views of incarceration and the meaning of this experience may affect their later adjustment to life in the community. On the basis of brief narrative responses collected during an epidemiological survey of the psychological health of prisoners in France, this study examined the impact of incarceration on psychological state in a group of 59 inmates serving long sentences. Qualitative content analysis and computer-assisted linguistic analysis (using ALCESTE software) were performed on the textual data of open responses to three standard questions. Using a combination of these two approaches, seven categories of the subjective experience of prisoners in the sample were identified: the Outside World, Others, Punishment, Time, Affects and Impulses, Self-Concept, and Speech. Further qualitative analyses were then performed to compare the responses of Severely Mentally Ill (SMI) subjects and subjects with no psychiatric disorder. These analyses revealed contrasting attitudes towards incarceration. SMI subjects spoke in more hostile and persecutory terms about their experience in prison, attributing suffering to external circumstances, while subjects with no psychiatric disorder evoked similar themes, but with an introspective attitude. The themes evoked by mentally ill individuals in our sample suggest that their reactions to the prison environment arise in part from aspects of their psychiatric symptoms, and this may have relevance to future mental health policy and practices in criminal corrections. PMID:19619895

  15. Time Management Managing Time and Tasks

    E-print Network

    Kasman, Alex

    Time Management Managing Time and Tasks What is time management? Time can't be managed ­ but you can manage the amount of time you use each day for fun, work, rest, and time spent with others. Why is time management important? You have responsibilities to yourself, to your family and friends, to your

  16. TIME & LABOR TRAINING MANUAL

    E-print Network

    Barrash, Warren

    1 TIME & LABOR TRAINING MANUAL TIME APPROVAL /2013 #12;2 TABLE OF CONTENTS TIME APPROVAL - THINGS TO REMEMBER ..................................................................... 3 TIME APPROVAL - QUICK GUIDE

  17. Time Commitments Where Does Your Time Go

    E-print Network

    Kasman, Alex

    Time Commitments Where Does Your Time Go Everyone starts the week with the same number of hours. So, why does your time go so fast? Let's find out! Number of hours of sleep each night ____ x 7 preparation/clean-up time) ____ x 7 = ____ Travel time to and from campus ___ x __ = ____ Number of hours per

  18. Correlated continuous time random walk with time averaged waiting time

    NASA Astrophysics Data System (ADS)

    Lv, Longjin; Ren, Fu-Yao; Wang, Jun; Xiao, Jianbin

    2015-03-01

    In this paper, we study the dynamics of a correlated continuous time random walk with time averaged waiting time. The mean square displacement (MSD) shows this process is subdiffusive and generalized Einstein relation holds. We also get the asymptotic behavior of the probability density function (PDF) of this process is stretched Gaussian. At last, by computing the time averaged MSD, we find ergodicity breaking occurs in this process.

  19. The Time-Pressure Illusion: Discretionary Time vs. Free Time

    ERIC Educational Resources Information Center

    Goodin, Robert E.; Rice, James Mahmud; Bittman, Michael; Saunders, Peter

    2005-01-01

    People's welfare is a function of both time and money. People can--and, it is said, increasingly do--suffer time-poverty as well as money-poverty. It is undeniably true that people feel increasingly time pressured, particularly in dual-earner households. But much of the time devoted to paid and unpaid tasks is over and above that which is strictly…

  20. Internet time synchronization: the network time protocol

    Microsoft Academic Search

    David L. Mills

    1991-01-01

    The network time protocol (NTP), which is designed to distribute time information in a large, diverse system, is described. It uses a symmetric architecture in which a distributed subnet of time servers operating in a self-organizing, hierarchical configuration synchronizes local clocks within the subnet and to national time standards via wire, radio, or calibrated atomic clock. The servers can also

  1. Timed Alternating-Time Temporal Logic

    Microsoft Academic Search

    Thomas A. Henzinger; Vinayak S. Prabhu

    2006-01-01

    We add freeze quantiers to the game logic ATL in order to specify real-time objectives for games played on timed structures. We dene the semantics of the resulting logic TATL by restricting the play- ers to physically meaningful strategies, which do not prevent time from diverging. We show that TATL can be model checked over timed automa- ton games. We

  2. Average-Time Games on Timed Automata

    E-print Network

    Jurdzinski, Marcin

    2009-01-01

    An average-time game is played on the infinite graph of configurations of a finite timed automaton. The two players, Min and Max, construct an infinite run of the automaton by taking turns to perform a timed transition. Player Min wants to minimise the average time per transition and player Max wants to maximise it. A solution of average-time games is presented using a reduction to average-price game on a finite graph. A direct consequence is an elementary proof of determinacy for average-time games. This complements our results for reachability-time games and partially solves a problem posed by Bouyer et al., to design an algorithm for solving average-price games on priced timed automata. The paper also establishes the exact computational complexity of solving average-time games: the problem is EXPTIME-complete for timed automata with at least two clocks.

  3. Terrific Time Telling

    NSDL National Science Digital Library

    Ms. Triola

    2009-04-19

    Have fun learning how to tell time! First, let's telling time with Dragon. Now that you can tell time with dragon, you have to choose the time!. Time can move fast. Do you think you can keep up? Use your knowledge of time to Stop the clock!. Now that you can keep up with time, can you decide What time will it be? Finally! You have learned so much about time, ...

  4. History without time: Buffon's natural history as a nonmathematical physique.

    PubMed

    Hoquet, Thierry

    2010-03-01

    While "natural history" is practically synonymous with the name of Buffon, the term itself has been otherwise overlooked by historians of science. This essay attempts to address this omission by investigating the meanings of "physique," "natural philosophy," and "history," among other terms, with the purpose of understanding Buffon's actual objectives. It also shows that Buffon never claimed to be a Newtonian and should not be considered as such; the goal is to provide a historical analysis that resituates Buffon's thought within his own era. This is done, primarily, by eschewing the often-studied question of time in Buffon. Instead, this study examines the nontemporal meanings of the word "history" within the naturalist's theory and method. The title of his Natural History is examined both as an indicator of the kind of science that Buffon was hoping to achieve and as a source of great misinterpretation among his peers. Unlike Buffon, many of his contemporaries actually envisioned the study of nature from a Baconian perspective where history was restricted to the mere collection of facts and where philosophy, which was the implicit and ultimate goal of studying nature, was seen, at least for the present, as unrealizable. Buffon confronts this tendency insofar as his Histoire naturelle claims to be the real physique that, along with describing nature, also sought to identify general laws and provide clear insight into what true knowledge of nature is or should be. According to Buffon, history (both natural and civil) is not analogous to mathematics; it is a nonmathematical method whose scope encompasses both nature and society. This methodological stance gives rise to the "physicization" of certain moral concepts--a gesture that was interpreted by his contemporaries as Epicurean and atheist. In addition, Buffon reduces a number of metaphysically tainted historical concepts (e.g., antediluvian monuments) to objects of physical analysis, thereby confronting the very foundation of natural theology. In Buffon, as this essay makes clear, natural history is paving the way for a new physique (science of natural beings), independent from mathematics and from God, that treats naturalia in a philosophical and "historical" manner that is not necessarily "temporal." PMID:20575489

  5. Babies Need Tummy Time

    MedlinePLUS

    ... Head FAQs Myths and Facts Babies Need Tummy Time! Skip sharing on social media links Share this: ... of your baby’s normal growth. What Is Tummy Time? Tummy Time describes the times when you place ...

  6. Geological Time Scale

    NSDL National Science Digital Library

    This document describes how geologic time is approached in discussions of geologic topics. The uses of relative time and absolute time are compared, and a geologic time scale is provided to represent both concepts. References are provided.

  7. Time on Your Hands: Modeling Time

    NSDL National Science Digital Library

    John Beaver

    2007-07-01

    Building physical models relative to a concept can be an important activity to help students develop and manipulate abstract ideas and mental models that often prove difficult to grasp. One such concept is time. A method for helping students understand the cyclical nature of time involves the construction of a Time Zone Calculator through a series of physical models. This article explains how to construct a Time Zone Calculator and provides suggestions for its use.

  8. Time Crystals from Minimum Time Uncertainty

    E-print Network

    Mir Faizal; Mohammed M. Khalil; Saurya Das

    2014-12-29

    Motivated by the Generalized Uncertainty Principle, covariance, and a minimum measurable time, we propose a deformation of the Heisenberg algebra, and show that this leads to corrections to all quantum mechanical systems. We also demonstrate that such a deformation implies a discrete spectrum for time. In other words, time behaves like a crystal.

  9. On the Time Times Temperature Bound

    NASA Astrophysics Data System (ADS)

    López-Ortega, A.

    Recently Hod proposed a lower bound on the relaxation time of a perturbed thermodynamic system. For gravitational systems this bound transforms into a condition on the fundamental quasinormal frequency. We test the bound in some space-times whose quasinormal frequencies are calculated exactly, as the three-dimensional BTZ black hole, the D-dimensional de Sitter space-time, and the D-dimensional Nariai space-time. We find that for some of these space-times their fundamental quasinormal frequencies do not satisfy the bound proposed by Hod.

  10. Influence of pole plant time on the performance of a special jump and plant exercise in the pole vault.

    PubMed

    Schade, Falk; Arampatzis, Adamantios

    2012-06-01

    The purpose of this study was to examine the effect of the timing of the pole plant during the stance phase of the jump on the energy level of the vaulter/pole system at take-off for a special pole vault take-off exercise (Jagodin). We hypothesised that an earlier pole plant would increase the pole energy at take-off compared to the energy decrease of the vaulter during the jump and plant complex and so lead to a higher total energy of the vaulter/pole system at take-off. Six male pole vaulters experienced three Jagodins each with different pole plant time building three groups of vaults (early, intermediate, late pole plant). Kinematic data of vaulter and pole were recorded, as were ground reaction forces measured at the end of the pole under the planting box and under the take-off foot. These measurements allowed the energy exchange between the vaulter and pole to be determined. We found neither statistical significant differences in the mechanical energy level of the vaulter/pole system during take-off between the three groups nor a relationship between the timing of the pole plant and the energy level of the vaulter-pole system during take-off. We conclude that although the timing of the pole plant influences the interactions between the vaulter, the pole, and the ground, it does not affect the athlete's performance. Although a late pole plant decreases the loss of energy by the vaulter during the take-off, this is counterbalanced by a decrease in the energy stored in the pole at take-off. PMID:22534564

  11. Cover times, blanket times, and majorizing measures

    E-print Network

    Ding, Jian; Peres, Yuval

    2010-01-01

    We exhibit a strong connection between cover times of graphs and Talagrand's theory of majorizing measures. In particular, we show that the cover time of any graph $G$ can be characterized, up to universal constants, by the square of Talagrand's $\\gamma_2$ functional applied to an appropriate metric space on the vertices of $G$. This allows us to resolve a number of open questions. We give a deterministic polynomial-time algorithm that computes the cover time to within an O(1) factor for any graph, answering a question of Aldous and Fill (1994). We also positively resolve the blanket time conjectures of Winkler and Zuckerman (1996), showing that for any graph, the blanket and cover times are within an O(1) factor. The best previous approximation factor for both these problems was $O((\\log \\log n)^2)$ for $n$-vertex graphs, due to Kahn, Kim, Lovasz, and Vu (2000).

  12. Space time and the passage of time

    E-print Network

    George F. R. Ellis; Rituparno Goswami

    2012-08-26

    This paper examines the various arguments that have been put forward suggesting either that time does not exist, or that it exists but its flow is not real. I argue that (i) time both exists and flows; (ii) an Evolving Block Universe (`EBU') model of spacetime adequately captures this feature, emphasizing the key differences between the past, present, and future; (iii) the associated surfaces of constant time are uniquely geometrically and physically determined in any realistic spacetime model based in General Relativity Theory; (iv) such a model is needed in order to capture the essential aspects of what is happening in circumstances where initial data does not uniquely determine the evolution of spacetime structure because quantum uncertainty plays a key role in that development. Assuming that the functioning of the mind is based in the physical brain, evidence from the way that the mind apprehends the flow of time prefers this evolving time model over those where there is no flow of time.

  13. Elapsed Time Two

    NSDL National Science Digital Library

    2010-01-01

    In this activity, students are prompted with a starting time on a clock and a certain amount of elapsed time. In “see” mode, students add time to the clock in order to see what time it will be after the elapsed time. In “guess” mode, students must enter in a guess for what time it will be given a starting time and elapsed time. This activity allows students to practice reading clocks and explore elapsing time. This activity includes supplemental materials, including background information about the topics covered, a description of how to use the application, and exploration questions for use with the java applet.

  14. Time Management Graduate Students

    E-print Network

    Kavanagh, Karen L.

    Time Management for Graduate Students #12;Discussion: What are your key time management challenges? #12;Your Time Management Goal Not to be "the perfect student" To get a little bit better in your time use every week! How? Get in touch with your time use priorities. Gain awareness of how you

  15. Toddler Reading Time

    MedlinePLUS

    ... a day of quality programming. Back Continue Choosing Books for Toddlers Toddlers want to feel included and ... story time turns into sing-along time. Keeping Books Available Read-aloud time isn't the only ...

  16. TIME SERIES Syllabus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii

    E-print Network

    Weber, Richard

    TIME SERIES Contents Syllabus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv 1 Models for time series 1 1.1 Time series data . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 3.3 Analysing the effects of smoothing . . . . . . . . . . . . . . . . . . . . 12 4 Estimation

  17. Media Time Family Pledge

    MedlinePLUS

    ... Media Time Family Pledge Family Life Listen Media Time Family Pledge Article Body At the beginning and ... them. Kids learn best with small lessons over time as opposed to one big lecture or sit- ...

  18. Intelligence, Inspection Time, and Decision Time.

    ERIC Educational Resources Information Center

    Bates, Timothy C.; Eysenck, Hans J.

    1993-01-01

    Relationships among Multidimensional Aptitude Battery scores, inspection time, choice reaction time, and the odd-man procedure were investigated for 63 female and 25 male adults. No significant relationships were found for these mental speed measures and the Eysenck Personality Questionnaire-Revised dimensions of extraversion, neuroticism, and…

  19. The Hands of Time

    NSDL National Science Digital Library

    National Security Agency Central Security Service

    2009-04-22

    Students explore the different ways to measure time and develop their understanding of how to tell time to the hour, half and quarter hours, and then five minute intervals. They identify time on analog and digital clocks and read a clock at the hour or half hour. They participate in timed events and keep time as record keepers. In the final lesson, students make a My Time Book.

  20. Timed Communicating Object Z

    Microsoft Academic Search

    Brendan P. Mahony; Jin Song Dong

    2000-01-01

    This paper describes a timed, multi- threaded object modeling notation for specifying real-time, concurrent, and re- active systems. The notation Timed Com- municating Object Z (TCOZ) builds on Object-Z's strengths in modeling com- plex data and algorithms, and on Timed CSP's strengths in modeling process con- trol and real-time interactions. TCOZ is novel in that it includes timing primitives, properly

  1. Deep Time: The Geologic Time Scale

    NSDL National Science Digital Library

    2011-04-25

    This page examines the issues involved in teaching students about the geologic time scale. There are suggestions for tackling troublesome issues in class as well as activities that can be used to clarify how geoscientists look at deep time. Five main concepts with which students struggle when thinking about Deep Time are addressed here: imagining or comprehending big numbers; the difference between relative and numerical age; the concept of "timescales"; the ways we know about the age of the Earth and other materials; and resolving perceived issues with religious beliefs.

  2. On Time. 6b: Quantum Mechanical Time

    E-print Network

    C. K. Raju

    2008-08-09

    The existence of small amounts of advanced radiation, or a tilt in the arrow of time, makes the basic equations of physics mixed-type functional differential equations. The novel features of such equations point to a microphysical structure of time. This corresponds to a change of logic at the microphysical level. We show that the resulting logic is a quantum logic. This provides a natural and rigorous explanation of quantum interference. This structured-time interpretation of quantum mechanics is briefly compared with various other interpretations of q.m.

  3. Initial Sensorimotor and Cardiovascular Data Acquired from Soyuz Landings: Establishing a Functional Performance Recovery Time Constant

    NASA Technical Reports Server (NTRS)

    Reschke, M. F.; Kozlovskaya, I. B.; Kofman, I. S.; Tomilovskaya, E. S.; Cerisano, J. M.; Bloomberg, J. J.; Stenger, M. B.; Platts, S. H.; Rukavishnikov, I. V.; Fomina, E. V.; Lee, S. M. C.; Wood, S. J.; Mulavara, A. P.; Feiveson, A. H.; Fisher, E. A.

    2015-01-01

    INTRODUCTION Testing of crew responses following long-duration flights has not been previously possible until a minimum of more than 24 hours after landing. As a result, it has not been possible to determine the trend of the early recovery process, nor has it been possible to accurately assess the full impact of the decrements associated with long-duration flight. To overcome these limitations, both the Russian and U.S. programs have implemented joint testing at the Soyuz landing site. This International Space Station research effort has been identified as the functional Field Test, and represents data collect on NASA, Russian, European Space Agency, and Japanese Aerospace Exploration Agency crews. RESEARCH The primary goal of this research is to determine functional abilities associated with long-duration space flight crews beginning as soon after landing as possible on the day of landing (typically within 1 to 1.5 hours). This goal has both sensorimotor and cardiovascular elements. To date, a total of 15 subjects have participated in a 'pilot' version of the full 'field test'. The full version of the 'field test' will assess functional sensorimotor measurements included hand/eye coordination, standing from a seated position (sit-to-stand), walking normally without falling, measurement of dynamic visual acuity, discriminating different forces generated with the hands (both strength and ability to judge just noticeable differences of force), standing from a prone position, coordinated walking involving tandem heel-to-toe placement (tested with eyes both closed and open), walking normally while avoiding obstacles of differing heights, and determining postural ataxia while standing (measurement of quiet stance). Sensorimotor performance has been obtained using video records, and data from body worn inertial sensors. The cardiovascular portion of the investigation has measured blood pressure and heart rate during a timed stand test in conjunction with postural ataxia testing (quiet stance sway) as well as cardiovascular responses during sensorimotor testing on all of the above measures. We have also collected motion sickness data associated with each of the postflight tests. When possible rudimentary cerebellar assessment was undertaken. In addition to the immediate post-landing collection of data, postflight data has been acquired twice more within 24 hours after landing and measurements continue until sensorimotor and cardiovascular responses have returned to preflight normative values (approximately 60 days postflight). SUMMARY The level of functional deficit observed in the crew tested to date is more severe than expected, clearly triggered by the acquisition of gravity loads immediately after landing when the demands for crew intervention in response to emergency operations will be greatest. Measureable performance parameters such as ability to perform a seat egress, recover from a fall or the ability to see clearly when walking, and related physiologic data (orthostatic responses) are required to provide an evidence base for characterizing programmatic risks and the degree of variability among crewmembers for exploration missions where the crew will be unassisted after landing. Overall, these early functional and related physiologic measurements will allow the estimation of nonlinear sensorimotor and cardiovascular recovery trends that have not been previously captured.

  4. Time Management for Directors

    ERIC Educational Resources Information Center

    Jaffe, Ellen Hofstetter

    2005-01-01

    Time management is a skill. Like any new skill, it takes time and commitment to develop. A frequent complaint of center directors is not having enough time. Most work extremely long hours and still feel they are not getting enough done. This article presents ideas on how to manage time and work smarter, not harder. These ideas are the following:…

  5. Traveling Through Time

    NSDL National Science Digital Library

    WGBH Educational Foundation

    2012-02-10

    This video excerpt from NOVA’s The Fabric of the Cosmos: The Illusion of Time explains gravity’s pull on time, and how time travel may be possible in the future. However, this kind of time travel might not be exactly like Hollywood’s depiction.

  6. Review of time scales. [Universal Time-Ephemeris Time-International Atomic Time

    NASA Technical Reports Server (NTRS)

    Guinot, B.

    1974-01-01

    The basic time scales are presented: International Atomic Time, Universal Time, and Universal Time (Coordinated). These scales must be maintained in order to satisfy specific requirements. It is shown how they are obtained and made available at a very high level of precision.

  7. Time and Teaching

    ERIC Educational Resources Information Center

    McEwan, Anna E.

    2012-01-01

    This essay invites reflection on the phenomena of time as it impacts the day-to-day life of teachers. It also explores assumptions about time and teaching in three areas: first, beliefs about the force of time and the teacher's struggle to control it; second, beliefs about the potential of time and the benefits of its passing for teachers and…

  8. Synchronized time stamp support

    SciTech Connect

    Kowalkowski, J.

    1994-02-16

    New software has been added to IOC core to maintain time stamps. The new software has the ability to maintain time stamps over all IOCs on a network. The purpose of this paper is to explain how EPICS will synchronize the time stamps. In addition, this paper will explain how to configure and use the new EPICS time stamp support software.

  9. Breathing Time Warp

    Microsoft Academic Search

    Jeff S. Steinrnan

    1993-01-01

    Time Warp and Breathing Time Buckets are two general-purpose optimistic synchronization strategies for supporting parallel discrete-event simulations. However, each one of these approaches has potential fatal shortcomings. Time Warp may exhibit rollback explosions that can cause an avalance of antimessages. Breathing Time Buckets, on the other hand, may not be able to process enough events per synchronization cycle to remain

  10. What Time Is It?

    NSDL National Science Digital Library

    Christen

    2010-05-26

    Practice telling time with these activities. Match the time of the analog clock to the correct digital clockAnalog vs. Digital. Race against time in Stop the Clock! Help the dragon Set the Clock to the correct time. Grab a partner to play Willy the Watchdog . ...

  11. From Time to Time: Processing Time Reference Violations in Dutch

    ERIC Educational Resources Information Center

    Dragoy, Olga; Stowe, Laurie A.; Bos, Laura S.; Bastiaanse, Roelien

    2012-01-01

    Time reference in Indo-European languages is marked on the verb. With tensed verb forms, the speaker can refer to the past (wrote, has written), present (writes, is writing) or future (will write). Reference to the past through verb morphology has been shown to be particularly vulnerable in agrammatic aphasia and both agrammatic and…

  12. On Time-II: Newton's Time.

    ERIC Educational Resources Information Center

    Raju, C. K.

    1991-01-01

    A study of time in Newtonian physics is presented. Newton's laws of motion, falsifiability and physical theories, laws of motion and law of gravitation, and Laplace's demon are discussed. Short bibliographic sketches of Laplace and Karl Popper are included. (KR)

  13. Time domain reflectometry in time variant plasmas

    NASA Technical Reports Server (NTRS)

    Scherner, Michael J.

    1992-01-01

    The effects of time-dependent electron density fluctuations on a synthesized time domain reflectometry response of a one-dimensional cold plasma sheath are considered. Numerical solutions of the Helmholtz wave equation, which describes the electric field of a normally incident plane wave in a specified static electron density profile, are used. A study of the effects of Doppler shifts resulting from moving density fluctuations in the electron density profile of the sheath is included. Varying electron density levels corrupt time domain and distance measurements. Reducing or modulating the electron density levels of a given electron density profile affects the time domain response of a plasma and results in motion of the turning point, and the effective motion has a significant effect on measuring electron density locations.

  14. Timing Yield Estimation from Static Timing Analysis

    Microsoft Academic Search

    Anne E. Gattiker; Sani R. Nassif; Rashmi Dinakar; Chris Long

    2001-01-01

    This paper presents a means for estimating parametric timing yield and guiding robust design for-quality in the presence of manufacturing and operating environment variations. Dual emphasis is on computational efficiency and providing meaningful robust-design guidance. Computational efficiency is achieved by basing the proposed methodology on a post-processing step applied to the report generated as a by-product of static timing analysis.

  15. Did time begin? Will time end?

    E-print Network

    Paul H. Frampton

    2007-05-14

    Did time begin at a Big Bang? Will the present expansion of the universe last for a finite or infinite time? These questions sound philosophical but are becoming, now in the twenty-first century, central to the scientific study of cosmology. The answers, which should become clarified in the next decade or two, could have profound implications for how we see our own role in the universe. Since the original publication of Stephen Hawking's {\\it A Brief History of Time} in 1988, the answers to these questions have progressed as a result of research by the community of active theoretical physicists including myself. To present the underlying ideas requires discussion of a wide range of topics in cosmology, especially the make up of the energy content of the universe. A brief summary of my conclusions, that of three different possibilities concerning the history and future of time, the least likely is the conventional wisdom (time began and will never end) and most likely is a cyclic model (time never begins or ends), is in the short final Chapter which could be read first. To understand the reasoning leading to my conclusions could encourage reading of my entire book. My hope in writing this, my first popular book, is that it will engender reflection about time. Many a non-scientist may already hold a philosophical opinion about whether time begins and ends. This book's aim is to present some recently discovered scientific facts which can focus the reader's consideration of the two short questions in my title.

  16. Tempus Fugit: Time Flies

    NSDL National Science Digital Library

    This online exhibit from a prominent American museum explores the character of time -- its impact on our daily lives and its ability to shape and reform human consciousness. Tempus Fugit: Time Flies is a superb exhibit from the Nelson Atkins Museum of Art that uses items from the museum to exemplify different understandings of time. The exhibit features sections on 20th Century Time, World Times, and Conservation Time. Twentieth-century time considers the changing nature of time in the technological age by examining the innovations in graphic and plastic arts inspired by an altered sense of time. The exhibit includes works by Muybridge, Edward Hopper, Salvador Dali, Kandinsky, Rothko, Roy Lichtenstein, and others. The second section, World Times, focuses on the different conceptions of time embodied in art from primitive times to the present and ranges from ancient Native American to Medieval Europe to ancestral Africa to the deeply cosmological perceptions of time in ancient Indian civilizations. Conservation Time takes visitors behind the scenes to see how conservation science can uncover the history of a work's composition and the changes wrought upon it over the course of its lifetime. The Website also offers ideas for teaching using the exhibits. In sum, this is an elegantly constructed and intelligent Website. To be sure, users will want to set aside some time for it as the graphics enforce their own meditative pace upon the viewer.

  17. Time-of-day effects on postural control and attentional capacities in children.

    PubMed

    Baccouch, Rym; Zarrouk, Nidhal; Chtourou, Hamdi; Rebai, Haithem; Sahli, Sonia

    2015-04-01

    The present study aimed to examine the effect of time-of-day on postural control, body temperature, and attentional capacities in 5-6year old children. Twelve male children (5-6-year-old) were asked to maintain an upright bipedal stance on a force platform with eyes open (EO) and eyes closed (EC) at 07:00, 10:00, 14:00, and 18:00h. Postural control was evaluated by center of pressure (CoP) surface area (CoPArea), CoP mean velocity (CoPVm), length of the CoP displacement as a function of the surface (LFS) ratio and Romberg's index (RI). Oral temperature and the simple reaction time were also recorded at the beginning of each test session. The one way ANOVA (4time-of-day) showed significant time-of-day effects on CoPArea (p<0.001), CoPVm (p<0.01), LFS ratio (p<0.001) and RI (p<0.01). Children's postural control was lower at 07:00h and at 14:00h in comparison with 10:00h and 18:00h. Likewise, the reaction time was significantly (p<0.001) better at 10:00h and 18:00h in comparison with 07:00h and 14:00h. Oral temperature was higher at 14:00h and 18:00h than 08:00h and 10:00h (p<0.001). In conclusion, the children's postural control fluctuates during the daytime (i.e., better postural control at 10:00h and at 18:00h) with a diurnal rhythm close to that of body temperature and attentional capacities. Therefore, the evaluation of changes in postural control of 5-6-year-old children using force plate measures is recommended in the middle morning or the late afternoon to avoid the post-awakening and the post-prandial phases. PMID:25623540

  18. Universal Time Tunneling

    E-print Network

    Guenter Nimtz

    2009-01-26

    How much time does a tunneling wave packet spent in traversing a barrier? Quantum mechanical calculations result in zero time inside a barrier . In the nineties analogous tunneling experiments with microwaves were carried out. The results agreed with quantum mechanical calculations. Electron tunneling time is hard to measure being extremely short and parasitic effects due to the electric charge of electrons may be dominant. However, quite recently the atomic ionization tunneling time has been measured. Experimental data of photonic, phononic, and electronic tunneling time is available now and will be presented. It appears that the tunneling time is a universal property independent of the field in question.

  19. Verification of timing routines

    SciTech Connect

    Creel, L.R.

    1980-01-01

    A method for verifying the validity of timing routines for benchmarking and other timing measurements at the Los Alamos Scientific Laboratory (LASL) is described. A program written for this purpose uses two methods. The first method compares stopwatch times and system-computed times, where a system-computed time is the result of a call to the system timing routine. The second method requires calculating elapsed machine cycles. The program is modular and uses standard Fortran. With only a few changes, it is possible across all LASL systems and can be used on non-LASL systems as well. A complete benchmark job mix should include a program of this type.

  20. Why do flamingos stand on one leg?

    PubMed

    Anderson, Matthew J; Williams, Sarah A

    2010-01-01

    A series of observational studies of captive Caribbean flamingos Phoenicopterus ruber were conducted to determine why flamingos rest on one leg. While frequently asked by the general public, this basic question has remained unanswered by the scientific community. Here we suggest that the latency of flamingos to initiate forward locomotion following resting on one leg is significantly longer than following resting on two, discounting the possibility that unipedal resting reduces muscle fatigue or enhances predatory escape. Additionally, we demonstrate that flamingos do not display lateral preferences at the individual or group levels when resting on one leg, with each bird dividing its resting time across both legs. We show that while flamingos prefer resting on one leg to two regardless of location, the percentage of birds resting on one leg is significantly higher among birds standing in the water than among those on land. Finally, we demonstrate a negative relationship between temperature and the percentage of observed birds resting on one leg, such that resting on one leg decreases as temperature rises. Results strongly suggest that unipedal resting aids flamingos in thermoregulation. PMID:19637281

  1. Systematically Controlling for the Influence of Age, Sex, Hertz and Time Post-Whole-Body Vibration Exposure on Four Measures of Physical Performance in Community-Dwelling Older Adults: A Randomized Cross-Over Study

    PubMed Central

    Merriman, Harold L.; Brahler, C. Jayne; Jackson, Kurt

    2011-01-01

    Though popular, there is little agreement on what whole-body vibration (WBV) parameters will optimize performance. This study aimed to clarify the effects of age, sex, hertz and time on four physical function indicators in community-dwelling older adults (N = 32). Participants were exposed to 2?min WBV per session at either 2?Hz or 26?Hz and outcome measures were recorded at 2, 20 and 40?min post-WBV. Timed get up-and-go and chair sit-and-reach performances improved post-WBV for both sexes, were significantly different between 2?Hz and 26?Hz treatments (P ? 0.05) and showed statistically significant interactions between age and gender (P ? 0.01). Counter movement jump and timed one-legged stance performances showed a similar but non-significant response to 2?Hz and 26?Hz treatments, though male subjects showed a distinct trended response. Age and gender should be statistically controlled and both 2?Hz and 26?Hz exert a treatment effect. PMID:21977028

  2. Scalesofclimaticvariabilityand time averagingin Pleistocenebiotas

    E-print Network

    Roy, Kaustuv

    REVIEWS 458 Scalesofclimaticvariabilityand time averagingin Pleistocenebiotas to climatic changes over a spectrum of time- scales, For example, data from marine and terrestrial settings climates Until recently, most analyses of the Pleistocene fossil record tacitly assumed that the major

  3. Time and Relativity

    NSDL National Science Digital Library

    2007-08-09

    This video from the American Museum of Natural History illustrates Einstein's special theory of relativity and the relationship between time and the motion of objects, including the concept of time dilation.

  4. TIMELY WARNING CAMPUS ALERT

    E-print Network

    Hardy, Christopher R.

    TIMELY WARNING CAMPUS ALERT 25 February 2008 This communication is prepared as part of the Timely-in's and at least three burglaries. The purpose of this communication is to not only alert the campus community

  5. TIMELY WARNING CAMPUS ALERT

    E-print Network

    Hardy, Christopher R.

    TIMELY WARNING CAMPUS ALERT April 5, 2007 This communication is prepared as part of the Timely wandering the halls. Two alert students reported the suspicious activity to the police as the suspects fled

  6. Geologic Time : Online Edition

    NSDL National Science Digital Library

    1997-01-01

    Offered by the United States Geological Survey (USGS) as a general interest publication, this site is an online edition of a text by the same name, offering a concise overview of the concepts associated with the age of the Earth. The online edition was revised in October of 1997 to reflect current thinking on this topic. Section headers are Geologic Time, Relative Time Scale, Major Divisions of Geologic Time, Index Fossils, Radiometric Time Scale, and Age of the Earth.

  7. Time-domain ptychography

    NASA Astrophysics Data System (ADS)

    Spangenberg, Dirk; Neethling, Pieter; Rohwer, Erich; Brügmann, Michael H.; Feurer, Thomas

    2015-02-01

    Through dedicated measurements in the optical regime we demonstrate that ptychography can be applied to reconstruct complex-valued object functions that vary with time from a sequence of spectral measurements. A probe pulse of approximately 1 ps duration, time delayed in increments of 0.25 ps, is shown to recover dynamics on a ten times faster time scale with an experimental limit of approximately 5 fs.

  8. TIMING IN CHILD DEVELOPMENT

    Microsoft Academic Search

    Kristyn Kuhlman; Lawrence J. Schweinhart

    This study investigated the metronome and musical timing of 585 four- to eleven-year-olds in Effingham, Illinois. A computer system measured metronome timing by counting the number of milliseconds that responses diffe red from a steady beat not embedded in music. Raters measured musical timing from videotaped responses to the steady beat embedded in instrumental music. Both measures were internally consistent.

  9. External Resource: Geologic Time

    NSDL National Science Digital Library

    1900-01-01

    This NASA sponsored webpage, Center for Educational Technologies, teaches students about Geologic Time. The age of Earth is so long compared to all periods of time that we humans are familiar with, it has been given a special name: Geologic time. The age

  10. Oncology and narrative time

    Microsoft Academic Search

    Mary-Jo Del Vecchio Good; Tseunetsugu Munakata; Yasuki Kobayashi; Cheryl Mattingly; Byron J. Good

    1994-01-01

    Oncologists encounter the uncertainty of time horizons in their patients' lives. Although American oncologists are given a cultural mandate to instill hope in the therapeutic narratives they create with patients, uncertainty leads them to expressions of time without horizons or of time with highly foreshortened horizons as they seek to create for patients an experience of immediacy rather than of

  11. Time-periodic universes

    E-print Network

    De-Xing Kong; Kefeng Liu; Ming Shen

    2008-08-30

    In this letter we construct a new time-periodic solution of the vacuum Einstein's field equations whose Riemann curvature norm takes the infinity at some points. We show that this solution is intrinsically time-periodic and describes a time-periodic universe with the "black hole". New physical phenomena are investigated and new singularities are analyzed for this universal model.

  12. Time Change No Smoking!

    E-print Network

    Pilyugin, Sergei S.

    Highlights · Time Change · No Smoking! · Birthdays · Manners TheELIWeekly Set Your Clocks Daylight week's Weekly. Smoking An extra reminder this week, folks. From time to time, there are people smoking in areas where they shouldn't be. We want to be good neighbors! Smoking is NOT permitted in the following

  13. Time Is Money

    ERIC Educational Resources Information Center

    Oxley, Diana; Baete, Glenn

    2012-01-01

    One has heard it before: time is money, especially when it comes to adding time for instruction to the school day. When budgets are tight and relief is nowhere in sight, how can schools afford to implement a reform as costly as adding instructional time? It's a daunting task, yet current federal educational priorities tied to federal funding…

  14. Noncommutative Two Time Physics

    E-print Network

    W. Chagas-Filho

    2006-05-10

    We present a classical formalism describing two-time physics with Abelian canonical gauge field backgrounds. The formalism can be used as a starting point for the construction of an interacting quantized two-time physics theory in a noncommutative soace-time.

  15. Time Service Department

    NSDL National Science Digital Library

    U.S. Navy

    This site from the US Navy is the official source of time for the Department of Defense (DoD) and the Global Positioning System (GPS), and a Standard of Time for the United States. It features numerous links to other useful time and GPS-related sites.

  16. Euglobulin lysis time

    MedlinePLUS

    Euglobulin lysis time (ELT) is a blood test that looks at how fast clots break down in the blood. ... A longer-than-normal ELT time may be due to: Diabetes Prematurity A shorter-than-normal ELT time may be due to: Blood vessel injury or surgery ...

  17. Time Matters Cynthia Selin

    E-print Network

    Time Matters Cynthia Selin Institute for Politics, Management and Philosophy Copenhagen Business of Nanotechnology ·Time & Nanotechnology ·Legitimization of Foresight ·Strategy #12;ON NANOTECHNOLOGY AS A FIELD 1. #12;TIME MATTERS · A diversity of timescapes are evident within the discourses of nanotechnology

  18. Figure This: Time Zones

    NSDL National Science Digital Library

    2004-01-01

    This is an activity featuring a time zone map useful when teaching an interdisciplinary social studies and math unit focusing on geography and the time zones. It underscores the role of the earth's rotation in everyday life, and the need to understand the relationships between earth rotation, day and night, and time zones around the world.

  19. Finding Structure in Time

    Microsoft Academic Search

    Jeffrey L. Elman

    1990-01-01

    Time underlies many interesting human behaviors. Thus, the question of how to represent time in connectionist models is very important. One approach is to represent time implicitly by its effects on processing rather than explicitly (as in a spatial representation). The current report develops a proposal along these lines first described by Jordan (1986) which involves the use of recurrent

  20. Elapsed Time Two

    NSDL National Science Digital Library

    2011-05-24

    This lesson is designed to develop students' understanding of elapsed time and how to find ending time given starting and elapsed times. This lesson provides links to discussions and activities related to the topic as well as suggested ways to integrate them into the lesson. Finally, the lesson provides links to follow-up lessons designed for use in succession with the current one.

  1. Real-time imaging

    Microsoft Academic Search

    P. A. Laplante

    2005-01-01

    Real-time imaging systems are a special class that underlies important application domains that include industrial, medical and military. The main characteristic of a real-time imaging system is the need for deadline satisfaction. Admittedly, this definition is very broad and vague. The case can be made that every system is real-time. In a \\

  2. Time Management for Educators.

    ERIC Educational Resources Information Center

    Burden, Paul R.

    Time management principles can help teachers become more aware of ways in which time can be used to the greatest advantage. An exploration of personal time perspectives is a step toward establishing effective patterns of behavior. Productivity may be high in the morning and low in the late afternoon, for example, and organizing some activities to…

  3. Big Time Tour

    NSDL National Science Digital Library

    University of Nebraska State Museum

    2002-01-01

    In this activity (on pages 16-21), learners get a sense of geological time by understanding how big a million is. Part One of the activity is the "Million Appreciation Lesson," which puts a million seconds, names in a phone book, and hiked steps into more familiar units. Part Two is "Investigating All Time," where learners make a time line for the history of the Earth using the length of their own arm to represent the total 4.5 billion year long scale. They mark major time zones, such as the age of the dinosaurs, at appropriate lengths along the time line.

  4. Space-Time-Matter

    E-print Network

    Gerald E. Marsh

    2014-08-14

    This essay examines our fundamental conceptions of time, spacetime, the asymmetry of time, and the motion of a quantum mechanical particle. The concept of time has multiple meanings and these are often confused in the literature and must be distinguished if any light is to be thrown on this age-old issue. The asymmetry of time also has different meanings that depend on context-although the fundamental time asymmetry is associated with the expansion of the universe. These and related issues are discussed in both classical and quantum mechanical contexts.

  5. Cosmic Times: Overview Lessons

    NSDL National Science Digital Library

    2013-10-08

    The Cosmic Times Gallery Walk and Cosmic Times Jigsaw lessons serve as extensions to the Cosmic Times suite of curriculum support materials. They are intended to provide an introduction to Cosmic Times as a whole, giving students the larger picture of how our understanding of the universe has changed over the last century. During the Gallery Walk lesson, students peruse the Cosmic Times posters to answer open-ended questions. During the Jigsaw lesson, students work in cooperative teams to understand the primary scientific advances over the past century that have contributed to our current understanding of the universe.

  6. A time representation

    E-print Network

    Lucas Lamata; Juan Leon

    2005-07-12

    The paper contains a proposal for an energy and time representation. We construct modes that correspond to fuzzy distributions around discrete values of energy or time. The modes form an orthogonal and complete set in the space of square integrable functions. Energy and time are self adjoint in the space spanned by the modes. The widths of the modes are analyzed as well as their energy-time uncertainty relations. The lower uncertainty attainable for the modes is shown. We also show times of arrival for massless particles.

  7. Filling the Time

    NSDL National Science Digital Library

    2010-01-01

    Build time sense into the schedule by asking learners to predict what can happen in a certain amount of time: We have 20 minutes before outdoor time. What can you get done? Everyone makes a prediction, for instance, how many rounds of a card game they’ll play or how many origami cranes they can make. Then, stop part-way through the time period and ask if anyone wants to revise their predictions. Available as a web page or downloadable pdf. Students should have some familiarity with time.

  8. Time scales in LISA

    E-print Network

    S. Pireaux

    2007-03-23

    The LISA mission is a space interferometer aiming at the detection of gravitational waves in the [$10^{-4}$,$10^{-1}$] Hz frequency band. In order to reach the gravitational wave detection level, a Time Delay Interferometry (TDI) method must be applied to get rid of (most of) the laser frequency noise and optical bench noise. This TDI analysis is carried out in terms of the coordinate time corresponding to the Barycentric Coordinate Reference System (BCRS), TCB, whereas the data at each of the three LISA stations is recorded in terms of each station proper time. We provide here the required proper time versus BCRS time transformation. We show that the difference in rate of station proper time versus TCB is of the order of $5 10^{-8}$. The difference between station proper times and TCB exhibits an oscillatory trend with a maximum amplitude of about $10^{-3}$ s.

  9. It's About Time!

    NASA Technical Reports Server (NTRS)

    Clark, Tom

    2000-01-01

    Everything we do in VLBI is connected to time. In this contribution, we review 28 orders of magnitude of the spectrum of time ranging from a few hundred femtoseconds (i.e. one degree of phase at X-band - Pi x 10(exp -13) seconds) upwards to tens of millions of years (i.e. ten million years Pi x 10(exp 14) seconds). In this discussion, we will pay special attention to the relation between the underlying oscillator (the frequency standard that defines a clock's rate) and the time kept by the clock (which counts the oscillations of the frequency standard). We will consider two different types of time - time kept by counting an atomic frequency standard (Hydrogen Maser or Cesium), and time reckoned by the rotation of the Earth underneath the stars and sun.

  10. Space and Time

    NSDL National Science Digital Library

    This fun Web site is part of OLogy, where kids can collect virtual trading cards and create projects with them. Here, they are introduced to space and time with six engaging and kid-friendly areas: Welcome to the Fourth Dimension, which looks at how time is needed to describe where you are in the fourth dimension; It's All Relative, an explanation of how time and space are different depending on your frame of reference; Mass Appeal, which uses the example of an elephant on a page of paper to explain how the Sun's mass causes space and time to bend; You Light Up My Life, how Arthur Eddington proved that Einstein's light-bending prediction was right; Everyday Einstein: Black Holes, an overview of these "bottomless dimples in space." and Time Travel Kit, a look at how the faster you move in space, the slower you move in time.

  11. Time card entry system

    SciTech Connect

    Montierth, B.S.

    1996-05-01

    The Time Card Entry System was developed to interface with the DOE Headquarters Electronic Time and Attendance (ETA) system. It features pop-up window pick lists for Work Breakdown Structure Numbers and Hour Codes and has extensive processing that ensures that time and attendance reported by the employee fulfills US Government/OMB requirements before Timekeepers process the data at the end of the two week payroll cycle using ETA. Tours of Duty (e.g. ten hour day, four day week with Friday through Sunday off), established in the ETA system, are imported into the Time Card Entry System by the Timekeepers. An individual`s Tour of Duty establishes the basis for validation of time of day and number of hours worked per day. At the end of the two week cycle, data is exported by the Timekeepers from the Time Card Entry System into ETA data files.

  12. On Time Performance Pressure

    NASA Technical Reports Server (NTRS)

    Connell, Linda; Wichner, David; Jakey, Abegael

    2013-01-01

    Within many operations, the pressures for on-time performance are high. Each month, on-time statistics are reported to the Department of Transportation and made public. There is a natural tendency for employees under pressure to do their best to meet these objectives. As a result, pressure to get the job done within the allotted time may cause personnel to deviate from procedures and policies. Additionally, inadequate or unavailable resources may drive employees to work around standard processes that are seen as barriers. However, bypassing practices to enable on-time performance may affect more than the statistics. ASRS reports often highlight on-time performance pressures which may result in impact across all workgroups in an attempt to achieve on-time performance. Reporters often provide in-depth insights into their experiences which can be used by industry to identify and focus on the implementation of systemic fixes.

  13. Multi-resolution entropy analysis of gait symmetry in neurological degenerative diseases and amyotrophic lateral sclerosis

    Microsoft Academic Search

    Fuyuan Liao; Jue Wang; Ping He

    2008-01-01

    Gait rhythm of patients with Parkinson's disease (PD), Huntington's disease (HD) and amyotrophic lateral sclerosis (ALS) has been studied focusing on the fractal and correlation properties of stride time fluctuations. In this study, we investigated gait asymmetry in these diseases using the multi-resolution entropy analysis of stance time fluctuations. Since stance time is likely to exhibit fluctuations across multiple spatial

  14. TimeStats

    NSDL National Science Digital Library

    2014-03-06

    Ever wonder how much time you spend on any given website? Now you can find out with TimeStats. This version of the Chrome extension allows users to collect stats on the websites they visit each day, week, or month. Users can even create graphs and charts to visually look at how much time they spend on these sites. This version is compatible with computers running Google Chrome 33 and newer.

  15. It's About Time

    NSDL National Science Digital Library

    2014-09-18

    In past times, ocean navigators tossed a piece of wood over the side of their ships and noted how long until the ship passed the wood. They used this time measurement and the length of the ship to calculate their speed and estimate how far they had traveled. In this activity, students act the part of a GPS signal traveling to the receiver to learn how travel time is converted to distance.

  16. Geologic Time Discussion Analogies

    NSDL National Science Digital Library

    Noah Fay

    The slides provide a fun way of discussing the immensity of geologic time and help to grasp the age of the earth, the time gaps between major geologic events, and the relative minuteness of humans time on earth. After the discussion with the class, students are given opportunity to develop their own analogies using "everyday" things (other than the calendar and money examples used in this activity).

  17. Space-time gestures

    Microsoft Academic Search

    Trevor Darrell; Alex Pentland

    1993-01-01

    A method for learning, tracking, and recognizing human gestures using a view-based approach to model articulated objects is presented. Objects are represented using sets of view models, rather than single templates. Stereotypical space-time patterns, i.e., gestures, are then matched to stored gesture patterns using dynamic time warping. Real-time performance is achieved by using special purpose correlation hardware and view prediction

  18. Matter: Space without Time

    E-print Network

    Yousef Ghazi-Tabatabai

    2012-11-19

    While Quantum Gravity remains elusive and Quantum Field Theory retains the interpretational difficulties of Quantum Mechanics, we have introduced an alternate approach to the unification of particles, fields, space and time, suggesting that the concept of matter as space without time provides a framework which unifies matter with spacetime and in which we anticipate the development of complete theories (ideally a single unified theory) describing observed 'particles, charges, fields and forces' solely with the geometry of our matter-space-time universe.

  19. Looking Back in Time

    NSDL National Science Digital Library

    This lesson plan will provide a concrete way for students to understand the concept of distance in space equals distance in time. This is done using information gathered from a timeline activity in Lesson 1: Earth, the Universe, and Culture. Students experiment with how distances are measured in space and create timelines to demonstrate the concept distance in space equals distance in time. This lesson is part of the "Swift: Eyes Through Time" collection that is available on the Teacher's Domain website.

  20. British Museum: Explore: Time

    NSDL National Science Digital Library

    What is time? What does it mean to us? These are a but a few of the arresting questions asked by the British Museum's online exhibit exploring the nature, structure, and history of time, time-keeping, and other related subjects. This particular section is part of their larger "Explore" online collection, and it draws on the British Museum's vast holdings to look into this scientific, cultural, and historical phenomenon. The site includes five sections, including Measuring and Keeping Time, Personal Time, and The Effects of Time. The Measuring and Keeping Time area is quite arresting, and it includes images of a Native American 'winter counts' cloth which served as a recorder of events that took place between 1785 and 1901. Moving on, The Effects of Time area is rather remarkable as well, as it contains material on how humans have attempted to stop or slow down the passage of time via techniques like retaining a youthful portrait of an aging ruler on coins and paper money.

  1. Fields of Time

    NSDL National Science Digital Library

    Stephen Greb

    This outdoor exercise shows students the great expanse of time that has elapsed between the formation of Earth and the emergence of living creatures, particularly humans. The great length of the football field helps reinforce the idea of the vast amounts of time that have passed. Starting on one goal line, they will mark off distances representing the times of various events, rocks, fossils, or geologic eras. The teacher can calculate the distances needed, or students can do it themselves in the classroom. A table is provided to help convert distances in yards to time in millions of years, and links to additional information are included.

  2. A Walk Through Time

    NSDL National Science Digital Library

    The Physics Laboratory of the National Institute of Standards and Technology (NIST) provides A Walk Through Time, a site devoted to examining the question of how humans have measured time throughout history. In one example, Egyptians created the first timepiece (shadow clock or sundial) in the approximate year of 1500 BC to measure "hours." Nowadays, the Physics Laboratory develops and operates the "standards of time and frequency and coordinates them with other world standards." Those interested in timekeeping methods and an historical perspective on the evolution of time measurement will find this site fascinating.

  3. On the Time Times Temperature Bound

    E-print Network

    A. Lopez-Ortega

    2010-06-28

    Recently Hod proposes a lower bound on the relaxation time of a perturbed thermodynamic system. For gravitational systems this bound transforms into a condition on the fundamental quasinormal frequency. We test the bound in some spacetimes whose quasinormal frequencies are calculated exactly, as the three-dimensional BTZ black hole, the D-dimensional de Sitter spacetime, and the D-dimensional Nariai spacetime. We find that for some of these spacetimes their fundamental quasinormal frequencies do not satisfy the bound proposed by Hod.

  4. Time functions as utilities

    E-print Network

    E. Minguzzi

    2009-09-04

    Every time function on spacetime gives a (continuous) total preordering of the spacetime events which respects the notion of causal precedence. The problem of the existence of a (semi-)time function on spacetime and the problem of recovering the causal structure starting from the set of time functions are studied. It is pointed out that these problems have an analog in the field of microeconomics known as utility theory. In a chronological spacetime the semi-time functions correspond to the utilities for the chronological relation, while in a K-causal (stably causal) spacetime the time functions correspond to the utilities for the K^+ relation (Seifert's relation). By exploiting this analogy, we are able to import some mathematical results, most notably Peleg's and Levin's theorems, to the spacetime framework. As a consequence, we prove that a K-causal (i.e. stably causal) spacetime admits a time function and that the time or temporal functions can be used to recover the K^+ (or Seifert) relation which indeed turns out to be the intersection of the time or temporal orderings. This result tells us in which circumstances it is possible to recover the chronological or causal relation starting from the set of time or temporal functions allowed by the spacetime. Moreover, it is proved that a chronological spacetime in which the closure of the causal relation is transitive (for instance a reflective spacetime) admits a semi-time function. Along the way a new proof avoiding smoothing techniques is given that the existence of a time function implies stable causality, and a new short proof of the equivalence between K-causality and stable causality is given which takes advantage of Levin's theorem and smoothing techniques.

  5. Music in Time (Spoleto)

    Microsoft Academic Search

    John Kennedy; Olivier Reboul; Marc Williams; Jenny Lin

    Today's composers are making extraordinary new music which is reconnecting audiences with the music of our time. The Music in Time series, directed by John Kennedy, brings these voices to Spoleto with recent works by today's major composers on the international stage, as well as music by young composers who are setting the course for the future. This year's series

  6. Risk, time and reason

    Microsoft Academic Search

    Andy Alaszewski; Adam Burgess

    2007-01-01

    Over time, a number of alternative approaches to risk have developed and, while these co-exist, they structure time in different ways and are grounded in different combinations of cognitive rationality and affect. The initial conceptualization of risk, which remains prominent, was based on the use of knowledge from past events to provide the context for choices which minimize harm in

  7. Water Molecule Residence Times

    NSDL National Science Digital Library

    Sill - Earth Systems Science

    2010-11-16

    How long will a molecule of Water stay in a particular reservoir? What is the average time a molecule of Water will stay in an ocean? What is the average time a molecule of water will stay in a river? A lake? As groundwater? A glacier? How long will a water vapor molecule stay suspended in the atmosphere? Why is the residence ...

  8. Estimating Distance and Time

    NSDL National Science Digital Library

    2008-07-18

    Students learn to estimate the time it takes to travel different distances based on an estimation of the time it takes to travel a part of the whole route. This reinforces basic fractional/ratio thinking, as well as early multiplication as repeated addition.

  9. Daylight Saving Time

    NSDL National Science Digital Library

    2010-03-12

    It is not difficult to understand that students may have a misconception that the clocks we use are directly related to Sun time and that changing the clocks will alter the Sun-Earth time relationship. This chapter and story deal with this misconception a

  10. Rates and Time

    NSDL National Science Digital Library

    This website showcases teaching activities, strategies and methods for teaching about dates, rates, and time that are used in the many disciplines encompassed by geoscience education. This site was created to support a session on Geologic Rates and Time at the Geological Society of America meeting in 2005.

  11. Managing Time and Stress.

    ERIC Educational Resources Information Center

    Huffstutter, Sandra; Smith, Stuart C.

    Chapter 14 of a revised volume on school leadership, this chapter offers many practical suggestions for managing time and reducing stress. The primary challenge is to unblock the route to effective time/stress management by recognizing unproductive values and attitudes (such as overreliance on the Protestant work ethic or the appearance of…

  12. Probabilistic Timed Behavior Trees

    Microsoft Academic Search

    Robert Colvin; Lars Grunske; Kirsten Winter

    2007-01-01

    The Behavior Tree notation has been developed as a method for systematically and traceably capturing user requirements. In this paper we extend the notation with probabilistic behaviour, so that relia- bility, performance, and other dependability properties can be expressed. The semantics of probabilistic timed Behavior Trees is given by mapping them to probabilistic timed automata. We gain advantages for require-

  13. PERT Completion Times Revisited

    Microsoft Academic Search

    Fred E. Williams

    2005-01-01

    Two sources of PERT completion time bias are well documented in the literature: near critical paths turning critical during execution and misspecified activity time probability models. Although simulation is clearly the most appropriate method for assessing project duration, most introductory discussions touch on these issues and move quickly to standard approximations, implying that PERT offers useful, if only approximate, project

  14. Distance-Time Graphs

    NSDL National Science Digital Library

    The representation is an animated slide show which: -describes a distance-time graph -explains what the slope of a distance time graph represents -explains its usefulness in understanding an objects motion This resource also includes an interactive test and review of the material, and can be downloaded for offline use.

  15. Timely Warning Update

    ERIC Educational Resources Information Center

    Stafford, Dolores

    2011-01-01

    A complaint received by the Department of Education alleged that Virginia Tech violated the "timely warning" requirements of the Clery Act on April 16, 2007, by not issuing specific campus-wide alerts once senior officials knew of the immediate threat to health and safety. The complaint also alleged that the University's timely warning policy, as…

  16. Time Series Data Library

    NSDL National Science Digital Library

    Hyndman, Robert

    This is a collection of time series datasets covering many application areas, but are all for time series analysis. Some of the topics covered are: agriculture, chemistry, crime, demography, ecology, finance, health, hydrology, industry, labor market, macroeconomics, physics, production, sales, sport, transportation, tourism, tree rings and utilities. The data are in text format, thus they can be used without any additional software.

  17. Predicting chaotic time series

    Microsoft Academic Search

    J. Doyne Farmer; John J. Sidorowich

    1987-01-01

    A forecasting technique for chaotic data is presented. After a time series has been embedded in a state space using delay coordinates, the induced nonlinear mapping is 'learned' using a local approximation. This makes it possible to make short-term predictions of the future behavior of a time series, using information based only on past values. An error estimate is presented

  18. Time Here, Time There, Time Everywhere: Teaching Young Children Time through Daily Routine

    ERIC Educational Resources Information Center

    Lee, Joohi; Lee, Joo Ok; Fox, Jill

    2009-01-01

    According to Piaget, 5- or 6-year-old children gradually acquire the concept of time based on events (Piaget, 1969). In his experiment of investigating children's time concepts, Piaget found that children of these ages were able to place pictures based on sequential events with some errors; the younger children made more errors. The National…

  19. The Measurement of Time

    E-print Network

    A. Boyarsky; P Gora

    2007-05-07

    We present a definition of time measurement based on high energy photons and the fundamental length scale, and show that, for macroscopic time, it is in accord with the Lorentz transformation of special relativity. To do this we define observer in a different way than in special relativity.

  20. Geologic Time Online Edition

    NSDL National Science Digital Library

    This tutorial will help students learn and understand the concepts of geologic time and the age of the Earth. They will investigate the geologic time scale and learn about the use of index fossils and radiometric dating to determine the age of rock formations and fossils.

  1. Time Management. Revised.

    ERIC Educational Resources Information Center

    Halverson, Don E.

    Effective management of time involves utilizing a few basic rules. These rules can be summarized as follows: (1) determine your goals and objectives in all major aspects of your life; (2) devote at least 25 percent of your work week to personal improvement in your managerial role; (3) block out a large amount of time daily for planning in your…

  2. Where in Time?

    NSDL National Science Digital Library

    David Sacks

    2005-10-01

    This engaging activity helps students construct their own understanding of Earth's history and understand the geologic time scale. While working through the activity, students learn science concepts related to geologic time and the value of cooperation and effective communication. The lesson is aligned to the following National Science Education Standards: Science as Inquiry, Earth's History, and the Nature of Science.

  3. Emergence of Time

    E-print Network

    M. Heller; W. Sasin

    1997-11-17

    In the groupoid approach to noncommutative quantization of gravity, gravitational field is quantized in terms of a C*-algebra A of complex valued funcions on a groupoid G (with convolution as multiplication). In the noncommutative quantum gravitational regime the concepts of space and time are meaningless. We study the "emergence of time" in the transition process from the noncommutative regime to the standard space-time geometry. Precise conditions are specified under which modular groups of the von Neumann algebra generated by A can be defined. These groups are interpreted as a state depending time flow. If the above conditions are further refined one obtains a state independent time flow. We show that quantum gravitational dynamics can be expressed in terms of modular groups.

  4. Mining Time Series Data

    NASA Astrophysics Data System (ADS)

    Ratanamahatana, Chotirat Ann; Lin, Jessica; Gunopulos, Dimitrios; Keogh, Eamonn; Vlachos, Michail; Das, Gautam

    Much of the world's supply of data is in the form of time series. In the last decade, there has been an explosion of interest in mining time series data. A number of new algorithms have been introduced to classify, cluster, segment, index, discover rules, and detect anomalies/novelties in time series. While these many different techniques used to solve these problems use a multitude of different techniques, they all have one common factor; they require some high level representation of the data, rather than the original raw data. These high level representations are necessary as a feature extraction step, or simply to make the storage, transmission, and computation of massive dataset feasible. A multitude of representations have been proposed in the literature, including spectral transforms, wavelets transforms, piecewise polynomials, eigenfunctions, and symbolic mappings. This chapter gives a high-level survey of time series Data Mining tasks, with an emphasis on time series representations.

  5. World Time Server

    NSDL National Science Digital Library

    This handy site gives times for locations worldwide. Users click on a location on the left-hand side of the screen, and the current time at that location, together with a graphic showing the area of the world, appears on the right. Users can opt to list locations by country or city, and the list is searchable. Perhaps most convenient for those making international conference calls or similarly time-fraught arrangements is the Future Event Planner function, which allows users to enter a location and a future date and time, and then a second location so that they can see, for example, what time it will be in Bangladesh when it is nine a.m. next Thursday in Denver.

  6. Time synchronized video systems

    NASA Technical Reports Server (NTRS)

    Burnett, Ron

    1994-01-01

    The idea of synchronizing multiple video recordings to some type of 'range' time has been tried to varying degrees of success in the past. Combining this requirement with existing time code standards (SMPTE) and the new innovations in desktop multimedia however, have afforded an opportunity to increase the flexibility and usefulness of such efforts without adding costs over the traditional data recording and reduction systems. The concept described can use IRIG, GPS or a battery backed internal clock as the master time source. By converting that time source to Vertical Interval Time Code or Longitudinal Time Code, both in accordance with the SMPTE standards, the user will obtain a tape that contains machine/computer readable time code suitable for use with editing equipment that is available off-the-shelf. Accuracy on playback is then determined by the playback system chosen by the user. Accuracies of +/- 2 frames are common among inexpensive systems and complete frame accuracy is more a matter of the users' budget than the capability of the recording system.

  7. Time synchronized video systems

    NASA Astrophysics Data System (ADS)

    Burnett, Ron

    1994-05-01

    The idea of synchronizing multiple video recordings to some type of 'range' time has been tried to varying degrees of success in the past. Combining this requirement with existing time code standards (SMPTE) and the new innovations in desktop multimedia however, have afforded an opportunity to increase the flexibility and usefulness of such efforts without adding costs over the traditional data recording and reduction systems. The concept described can use IRIG, GPS or a battery backed internal clock as the master time source. By converting that time source to Vertical Interval Time Code or Longitudinal Time Code, both in accordance with the SMPTE standards, the user will obtain a tape that contains machine/computer readable time code suitable for use with editing equipment that is available off-the-shelf. Accuracy on playback is then determined by the playback system chosen by the user. Accuracies of +/- 2 frames are common among inexpensive systems and complete frame accuracy is more a matter of the users' budget than the capability of the recording system.

  8. Generative pulsar timing analysis

    NASA Astrophysics Data System (ADS)

    Lentati, L.; Alexander, P.; Hobson, M. P.

    2015-03-01

    A new Bayesian method for the analysis of folded pulsar timing data is presented that allows for the simultaneous evaluation of evolution in the pulse profile in either frequency or time, along with the timing model and additional stochastic processes such as red spin noise, or dispersion measure variations. We model the pulse profiles using `shapelets' - a complete orthonormal set of basis functions that allow us to recreate any physical profile shape. Any evolution in the profiles can then be described as either an arbitrary number of independent profiles, or using some functional form. We perform simulations to compare this approach with established methods for pulsar timing analysis, and to demonstrate model selection between different evolutionary scenarios using the Bayesian evidence. The simplicity of our method allows for many possible extensions, such as including models for correlated noise in the pulse profile, or broadening of the pulse profiles due to scattering. As such, while it is a marked departure from standard pulsar timing analysis methods, it has clear applications for both new and current data sets, such as those from the European Pulsar Timing Array and International Pulsar Timing Array.

  9. The Time Series Toolbox

    NASA Astrophysics Data System (ADS)

    Boži?, Bojan; Havlik, Denis

    2010-05-01

    Many applications commonly used in sensor service networks operate on the same type of data repeatedly over time. This kind of data is most naturally represented in the form of "time series". In its simplest form, a time series may consist of a single floating point number (e.g. temperature), that is recorded at regular intervals. More complex forms of time series include time series of complex observations (e.g. aggregations of related measurements, spectra, 2D coverages/images, ...), and time series recorded at irregular intervals. In addition, the time series may contain meta-information describing e.g. the provenance, uncertainty, and reliability of observations. The Time Series Toolbox (TS Toolbox) provides a set of software components and application programming interfaces that simplify recording, storage, processing and publishing of time series. This includes (1) "data connector" components implementing access to data using various protocols and data formats; (2) core components interfacing with the connector components and providing specific additional functionalities like data processing or caching; and (3) front-end components implementing interface functionality (user interfaces or software interfaces). The functionalities implemented by TS Toolbox components provide application developers with higher-level building blocks than typical general purpose libraries, and allow rapid development of fully fledged applications. The TS Toolbox also includes example applications that can be either used as they are, or as a basis for developing more complex applications. The TS-Toolbox, which was initially developed by the Austrian Institute of Technology in the scope of SANY "Sensors Anywhere", is written in Java, published under the terms of the GPL, and available for download on the SANY web site.

  10. Environment Induced Time Arrow

    E-print Network

    Janos Polonyi

    2012-06-25

    The spread of the time arrows from the environment to an observed subsystem is followed within a harmonic model. A similarity is pointed out between irreversibility and a phase with spontaneously broken symmetry. The causal structure of interaction might be lost in the irreversible case, as well. The Closed Time Path formalism is developed for classical systems and shown to handle the time arrow problem in a clear and flexible manner. The quantum case is considered, as well, and the common origin of irreversibility and decoherence is pointed out.

  11. RescueTime

    NSDL National Science Digital Library

    2013-05-30

    Almost everyone has had the experience of stopping work for a quick email check�and losing an hour in the process. RescueTime is designed to help users become better at self-management of time by showing them where they spend the most time on the computer. Users can choose when to turn the application on, set goals and track progress towards them, and sign up to receive weekly email summaries of their productivity. This program is compatible with Windows, OS X, Linux, and Android operating systems.

  12. Effective Quantum Time Travel

    E-print Network

    George Svetlichny

    2009-02-27

    The quantum teleportation protocol can be used to probabilistically simulate a quantum circuit with backward-in-time connections. This allows us to analyze some conceptual problems of time travel in the context of physically realizable situations, to realize encrypted measurements of future states for which the decryption key becomes available only after the state is created, and to probabilistically realize a multistage quantum state processing within the time needed to complete only one stage. The probabilistic nature of the process resolves any paradox.

  13. Paradoxes of time travel

    E-print Network

    S. Krasnikov

    1996-03-25

    Paradoxes that can supposedly occur if a time machine is created are discussed. It is shown that the existence of trajectories of ``multiplicity zero'' (i.e. trajectories that describe a ball hitting its younger self so that the latter cannot fall into the time machine) is not paradoxical by itself. This {\\em apparent paradox} can be resolved (at least sometimes) without any harm to local physics or to the time machine. Also a simple model is adduced for which the absence of {\\em true} paradoxes caused by self-interaction is proved.

  14. Focus Issue: Time Passages

    NSDL National Science Digital Library

    Lisa D. Chong (American Association for the Advancement of Science; Associate Editor of Science's STKE and Associate Editor of Science REV)

    2003-07-22

    The development of life remains one of the most fascinating topics in modern biology. Our quest to discover unifying principles is rooted in a desire to find reason and order in processes that are at once overwhelming and chaotic. We have been vigorously engaged in dissecting development across species at molecular and genomic levels. The intricate machineries that have been uncovered so far operate together in precise manners, at not only the right places, but equally important, at the correct times. This week, Science's Special Issue on Developmental Timing describes our knowledge of some of the rules and measures of time, a core dimension in understanding how development is controlled.

  15. Einstein and His Times

    NSDL National Science Digital Library

    2012-08-03

    In this lesson, students will read about and research the major historical events that occurred throughout the year 1919. They will use different readings and articles to understand and describe what life was like during this time. In addition, the students will present their case as to whether or not Albert Einstein should be voted "Man of the Year" for 1919. This activity is from the Cosmic Times teachers guide and is intended to be used in conjunction with the 1919 Cosmic Times Poster.

  16. Asia Times Online

    NSDL National Science Digital Library

    As the world's news flows increasingly from Asian nations, those people looking for a credible online source that concentrates on this region will find it in Asia Times Online. The site's front page features top stories from Asia Times journalists as well as from other online dailies and reports, including the South China Morning Post, Business Times Online, and the Australian Financial Review. The site offers separate sections for China, Southeast Asia, Japan, the Koreas, India/ Pakistan, Central Asia, and Oceania as well as departments devoted to Business Briefs, Global Economy, and Media and Industrial Technology. The entire site, including archives, is searchable.

  17. myMeetingTime

    NSDL National Science Digital Library

    Trying to plan a meeting for folks in Bangalore and Birmingham? That can be a challenge, but worry no longer: myMeetingTime is here. This handy site can help groups and organizations coordinate synchronous meetings all over the world. Visitors just need to type in their location and they can use the time zone converter and other tools to share possible meeting times with participants. It's much easier than chains of emails and the like. This version is compatible with all operating systems.

  18. Understanding Geological Time

    NSDL National Science Digital Library

    In this classroom activity, middle school students gain an understanding of geologic time. The activity opens with background information for teachers about carbon and radiometric dating. In a classroom discussion, students share what they know about geologic time. Then, working in small groups responsible for different eras, students create a timeline for their assigned era by conducting library and Internet research. The activity concludes by having students review all the timelines to compare how long humans have been on the Earth to the length of time dinosaurs inhabited the planet.

  19. How Emotions Change Time

    PubMed Central

    Schirmer, Annett

    2011-01-01

    Experimental evidence suggests that emotions can both speed-up and slow-down the internal clock. Speeding up has been observed for to-be-timed emotional stimuli that have the capacity to sustain attention, whereas slowing down has been observed for to-be-timed neutral stimuli that are presented in the context of emotional distractors. These effects have been explained by mechanisms that involve changes in bodily arousal, attention, or sentience. A review of these mechanisms suggests both merits and difficulties in the explanation of the emotion-timing link. Therefore, a hybrid mechanism involving stimulus-specific sentient representations is proposed as a candidate for mediating emotional influences on time. According to this proposal, emotional events enhance sentient representations, which in turn support temporal estimates. Emotional stimuli with a larger share in ones sentience are then perceived as longer than neutral stimuli with a smaller share. PMID:22065952

  20. Time Lapse Season Demonstrator

    NSDL National Science Digital Library

    University of Nebraska - Lincoln

    This animation demonstrates the changing declination of the sun with a time-lapse animation. It shows how the shadow of a building changes over the course of a year as the declination of the sun changes.

  1. Tsunami Travel Time Approximation

    NSDL National Science Digital Library

    Eric Grosfils

    Eric Grosfils, Pomona College Summary Students are asked to calculate approximate tsunami travel times across the Pacific basin. The assignment builds off of a lab introducing students to Spatial Analyst, and ...

  2. Right Place, Wrong Time

    NSDL National Science Digital Library

    Juanita Constible

    2008-10-01

    Songbirds tend to breed at the same time their primary prey is most abundant. Climate warming appears to be disrupting this match, causing reproductive failures in some species. Scientists have detected the consequences of warming for birds primarily thro

  3. Mathematics, time, and confirmation

    E-print Network

    Meyer, Ulrich, 1968-

    2001-01-01

    This dissertation discusses two issues about abstract objects: their role in scientific theories, and their relation to time. Chapter 1, "Why Apply Mathematics?" argues that scientific theories are not about the mathematics ...

  4. The Grand Time Game

    NSDL National Science Digital Library

    The Grand Time Game is a collection of activities that teach students about geologic time. The game elements consist of a tabletop model that demonstrates the geologic history of the Grand Canyon, a script in which students report selected events along the geologic time scale as the instructor operates the model, and a set of overhead transparencies that the instructor shows to illustrate the story. The materials also include an activity sheet for students to record important events as they progress, and a card game about fossils and geologic time, played in groups of three or four students after the script reading (the cards can also be pasted onto a calendar or timeline). Instructions for building the model are provided.

  5. TUESDAYTUESDAY Class Room Time

    E-print Network

    Hemmers, Oliver

    and cardiovascular fitness. CoreX Short on time or looking for that extra push? Let us get your heart pumping on a first come first serve basis. All fitness and experience levels welcome at all classes! No registration

  6. Time scales for sonoluminescence

    SciTech Connect

    Weninger, K.; Hiller, R.; Putterman, S.; Barber, B.P. (Phys. Dept., UCLA, Los Angeles, CA 90024 (United States))

    1994-11-01

    The establishment of stable sonoluminescence from a single trapped bubble of air in water requires more than 5 s. During this time the bubble goes through a transition period (about 1 s long) that is characterized by an emitted intensity which is over ten times smaller than the steady state. Pure noble gas bubbles turn on to their steady state values on a much shorter time scale (say less than 0.2 s). During the transient period light from an air bubble is weaker than light from an Argon bubble but in the steady state the air bubble is brighter. In view of the long time scale required for the establishment of sonoluminescence from a single bubble of air it is concluded that this is a fundamentally different phenomenon from the transient multibubble sonoluminescence that has been studied since its discovery in 1934. [Work supported by the U.S. DOE Division of Advanced Energy Projects.

  7. Drug Retention Times

    SciTech Connect

    Center for Human Reliability Studies

    2007-05-01

    The purpose of this monograph is to provide information on drug retention times in the human body. The information provided is based on plausible illegal drug use activities that might be engaged in by a recreational drug user.

  8. Drug Retention Times

    SciTech Connect

    Center for Human Reliability Studies

    2007-05-01

    The purpose of this monograph is to provide information on drug retention times in the human body. The information provided is based on plausible illegal drug use activities that might be engaged in by a recreational drug user

  9. Time, energy & form

    E-print Network

    McInnis, Martha Jane

    1982-01-01

    Physical manifestations of time occur in natural forms of all sizes. Architectural form serves as shelter while providing a built envelope of human life, simultaneously influencing and influenced by energetic activities ...

  10. Time to Go Local!

    MedlinePLUS

    ... Bar Home Current Issue Past Issues Time to Go Local! Past Issues / Winter 2007 Table of Contents ... MedlinePlus.gov health topic pages, you will find "Go Local" links that take you to information about ...

  11. Kairoscope : coordinating time socially

    E-print Network

    Martin, Reed Eric

    2010-01-01

    If everyone says time is relative, why is it still so rigidly defined? There have been many attempts to address the issue of coordinating schedules, but each of these attempts runs into an issue of rigidity: in order to ...

  12. Position versus Time Graph

    NSDL National Science Digital Library

    Wolfgang Christian

    An animation of a red car moving to the right, hitting a wall and then moving backward to the left is shown. Also shown is one of four possible graphs depicting the car's position as a function of time.

  13. Shape-Time Photography

    E-print Network

    Freeman, William T.

    2002-01-10

    We introduce a new method to describe, in a single image, changes in shape over time. We acquire both range and image information with a stationary stereo camera. From the pictures taken, we display a composite image ...

  14. Global Temperature Time Series

    NSDL National Science Digital Library

    The phenomenon is the rising and falling of temperatures on the Earth's surface. Click to choose a city on a regional map, showing graphs of the daily maximum, minimum, and mean temperatures for a 365 day time period.

  15. Web Geologic Time Scale

    NSDL National Science Digital Library

    The University of California-Berkeley Museum of Paleontology (last mentioned in the June 16, 1995 Scout Report) has recently updated its Web Geologic Time Scale, an online feature that helps users learn about the geologic timeline and explore related museum exhibits. The familiar geologic timeline appears on the main page of the Web site, with hypertext links for each division of time. Every page of the Web Geologic Time Machine site is liberally sprinkled with links to related UCMP Web pages; think of it as a portal to all online information available from the museum. Altogether, this Web site provides a well-organized and comprehensive resource for learning how the planet has changed over time, and would be a great addition to earth or life sciences classroom material for a broad range of grades.

  16. Time reversing solitary waves.

    PubMed

    Fouque, Jean-Pierre; Garnier, Josselin; Muñoz Grajales, Juan Carlos; Nachbin, André

    2004-03-01

    We present new results for the time reversal of nonlinear pulses traveling in a random medium, in particular for solitary waves. We consider long water waves propagating in the presence of a spatially random depth. Both hyperbolic and dispersive regimes are considered. We demonstrate that in the presence of properly scaled stochastic forcing the solution to the nonlinear (shallow water) conservation law is regularized leading to a viscous shock profile. This enables time-reversal experiments beyond the critical time for shock formation. Furthermore, we present numerical experiments for the time-reversed refocusing of solitary waves in a regime where theory is not yet available. Solitary wave refocusing simulations are performed with a new Boussinesq model, both in transmission and in reflection. PMID:15089472

  17. Sublinear Time Algorithms

    E-print Network

    Rubinfeld, Ronitt

    Sublinear time algorithms represent a new paradigm in computing, where an algorithm must give some sort of an answer after inspecting only a very small portion of the input. We discuss the types of answers that one can ...

  18. The Nature of Time

    E-print Network

    Julian Barbour

    2009-03-20

    A review of some basic facts of classical dynamics shows that time, or precisely duration, is redundant as a fundamental concept. Duration and the behaviour of clocks emerge from a timeless law that governs change.

  19. Imagining Deep Time (Invited)

    NASA Astrophysics Data System (ADS)

    Talasek, J.

    2013-12-01

    Imagining Deep Time '...the mind seemed to grow giddy by looking so far into the abyss of time.' John Playfair (1748 -1819), scientist and mathematician "Man cannot afford to conceive of nature and exclude himself." Emmit Gowin, photographer 'A person would have to take themselves out of the human context to begin to think in terms of geologic time. They would have to think like a rock.' Terry Falke, photographer The term Deep Time refers to the vastness of the geological time scale. First conceived in the 18th century, the development of this perspective on time has been pieced together like a jigsaw puzzle of information and observations drawn from the study of the earth's structure and discovered fossilized flora and fauna. Deep time may possibly be the greatest contribution made by the discipline of geology forever impacting our perception of earth and our relationship to it. How do we grasp such vast concepts as deep time which relates to the origins of the earth or cosmic time which relates to the origins of the universe - concepts that exist far beyond the realm of human experience? Further more how do we communicate this? The ability to visualize is a powerful tool of discovery and communication for the scientist and it is part and parcel of the work of visual artists. The scientific process provides evidence yet it is imagination on the part of the scientists and artists alike that is needed to interpret that information. This exhibition represents an area where both rational and intuitive thinking come together to explore this question of how we relate to the vastness of time. The answer suggested by the combination of art work assembled here suggests that we do so through a combination of visual metaphors (cycles, circles, arrows, trajectories) and visual evidence (rock formations, strata, fossils of fauna and flora) while being mediated through various technologies. One provides factual and empirical evidence while the other provides a way of grasping and relating to a vast concept on a personal level. This exhibition explores the usefulness as well as the limitations of the visualization of deep time.

  20. Time focusing of nutrons

    Microsoft Academic Search

    A. I. Frank; R. Gähler

    2000-01-01

    The possibility of time focusing for very slow neutrons is considered. This focusing may prove very useful in solving the\\u000a problem of accumulating ultracold neutrons in a trap that are generated by a pulsed source. Diffraction at a phase grating\\u000a moving across a beam or resonance neutron-spin flip is proposed to implement time-controlled changes in the neutron energy.

  1. Timing driven maze routing

    Microsoft Academic Search

    Sung-Woo Hur; Ashok Jagannathan; John Lillis

    1999-01-01

    Abstract—This paper studies a natural formulation of the timing-driven maze,routing problem. A multigraph model ap- propriate for global routing applications is adopted; the model naturally captures blockages, limited routing and wire-sizing resources, layer assignment, etc. Each edge in the multigraph is annotated with resistance and capacitance values associated with the particular wiring segment. The timing-driven maze routing problem is then

  2. TIMED Spacecraft Mobile

    NSDL National Science Digital Library

    2012-08-03

    This is a mobile for learners to assemble, aimed at enhancing their knowledge of NASA spacecraft and scientific facts. Each hanging element of the mobile contains an image and one fact or scientific concept related to the TIMED (Thermosphere, Ionosphere, Mesosphere, Energetics, and Dynamics) spacecraft mission. The cover contains background information about NASA's TIMED mission and two language arts exercises to reinforce space science vocabulary.

  3. American Time Use Survey

    Cancer.gov

    The American Time Use Survey (ATUS), conducted by the US Department of Labor, Bureau of Labor Statistics, is designed to collect information on how Americans spend their time on work, household chores, child care, recreation and other activities. The Applied Research Program (ARP) has provided funds to the US Department of Agriculture, Economic Research Service (USDA, ERS) to support the Eating and Health Module of the ATUS.

  4. Timing a Speedbot!

    NSDL National Science Digital Library

    AMPS GK-12 Program,

    Students strengthen their communicate skills about measurements by learning the meaning of base units and derived units, including speed—one of the most common derived units (distance/time). Working in groups, students measure the time for LEGO® MINDSTORMS® NXT robots to move a certain distance. The robots are started and stopped via touch sensors and programmed to display the distance traveled. Using their collected data, students complete a worksheet to calculate the robots' (mean/average) speeds at given motor powers.

  5. Event-Time Data

    Microsoft Academic Search

    Michelle Shardell; Daniel O. Scharfstein; Samuel A. Bozzette

    SUMMARY Interval-censored, or more generally, coarsened event-time data arise when study participants are observed at irregular time periods and experience the event of interest in between study observations. Such data are often analyzed assuming non-informative censoring, which can produce biased results if the assumption is wrong. This paper extends the standard approach for estimating survivor functions to allow informatively interval-censored

  6. Periodic Time Series Models

    Microsoft Academic Search

    Philip Hans Franses; Richard Paap

    2004-01-01

    This book considers periodic time series models for seasonal data, characterized by parameters that differ across the seasons, and focuses on their usefulness for out-of-sample forecasting. Providing an up-to-date survey of the recent developments in periodic time series, the book presents a large number of empirical results. The first part of the book deals with model selection, diagnostic checking and

  7. The Los Angeles Times

    NSDL National Science Digital Library

    The Los Angeles Times debuts its Internet edition April 8. It is slated to include daily news and features, coverage of movies and entertainment, a computers and technology section, a special section devoted to Southern California sights and events, classified advertising, and chat boards. The site will be free. A fee based site will also be available, with access to Times' archives, as well as educational and research services. http://www.latimes.com

  8. Time-Distance Helioseismology

    NASA Technical Reports Server (NTRS)

    Duvall, Thomas L., Jr.

    2010-01-01

    Time-distance helioseismology is a method of ambient noise imaging using the solar oscillations. The basic realization that led to time-distance helioseismology was that the temporal cross correlation of the signals at two 'surface' (or photospheric) locations should show a feature at the time lag corresponding to the subsurface travel time between the locations. The temporal cross correlation, as a function of the location separation, is the Fourier transform of the spatio-temporal power spectrum of the solar oscillations, a commonly used function in helioseismology. It is therefore likely the characteristic ridge structure of the correlation function had been seen before without appreciation of its significance. Travel times are measured from the cross correlations. The times are sensitive to a number of important subsurface solar phenomena. These include sound speed variations, flows, and magnetic fields. There has been much interesting progress in the 17 years since the first paper on this subject (Duvall et al., Nature, 1993, 362, 430-432). This progress will be reviewed in this paper.

  9. The thermodynamics of time

    E-print Network

    Dries Sels; Michiel Wouters

    2015-01-22

    The problem of time is a deep paradox in our physical description of the world. According to Aristotle's relational theory, time is a measure of change and does not exist on its own. In contrast, quantum mechanics, just like Newtonian mechanics, is equipped with a master clock that dictates the evolution of a system. This clock is infinitely precise and tacitly supplied free of charge from outside physics. Not only does this absolute time make it notoriously difficult to make a consistent theory of quantum gravity, it is also the underlying problem in establishing the second law. Indeed, contrary to our experience, the Wheeler-deWitt equation --a canonical quantization of general relativity-- predicts a static universe. Similarly, when simply concerned with the dynamics of a closed quantum system, there is no second law because the Von Neumann entropy is invariant under unitary transformations. Here we are mainly concerned with the latter problem and we show that it can be resolved by attributing a minimal amount of resources to the measurement of time. Although there is an absolute time in quantum mechanics, an observer can only establish a time by measuring a clock. For a local measurement, the minimal entropy production is equal to the number of ticks. This lower bound is attained by a black hole.

  10. GABA Predicts Time Perception

    PubMed Central

    Russo, Sonia; Near, Jamie; Stagg, Charlotte J.; Cohen Kadosh, Roi

    2014-01-01

    Our perception of time constrains our experience of the world and exerts a pivotal influence over a myriad array of cognitive and motor functions. There is emerging evidence that the perceived duration of subsecond intervals is driven by sensory-specific neural activity in human and nonhuman animals, but the mechanisms underlying individual differences in time perception remain elusive. We tested the hypothesis that elevated visual cortex GABA impairs the coding of particular visual stimuli, resulting in a dampening of visual processing and concomitant positive time-order error (relative underestimation) in the perceived duration of subsecond visual intervals. Participants completed psychophysical tasks measuring visual interval discrimination and temporal reproduction and we measured in vivo resting state GABA in visual cortex using magnetic resonance spectroscopy. Time-order error selectively correlated with GABA concentrations in visual cortex, with elevated GABA associated with a rightward horizontal shift in psychometric functions, reflecting a positive time-order error (relative underestimation). These results demonstrate anatomical, neurochemical, and task specificity and suggest that visual cortex GABA contributes to individual differences in time perception. PMID:24647956

  11. Estimation of Quasi-Stiffness of the Human Knee in the Stance Phase of Walking

    E-print Network

    Dollar, Aaron M.

    prosthetic limbs [7­10]. Ideally, successful emulation of human locomotion in artificial systems is built data characterizing the quasi-stiffness of lower-limb joints during human locomotion is limited framework and foundation for selecting subject-specific stiffness for prosthetic and exoskeletal devices

  12. Lexical Bundle Analysis in Mathematics Classroom Discourse: The Significance of Stance

    ERIC Educational Resources Information Center

    Herbel-Eisenmann, Beth; Wagner, David; Cortes, Viviana

    2010-01-01

    In this article, we introduce the lexical bundle, defined by corpus linguists as a group of three or more words that frequently recur together, in a single group, in a particular register (Biber, Johansson, Leech, Conrad, & Finegan, 2006; Cortes, "English for Specific Purposes" 23:397-423, 2004). Attention to lexical bundles helps to explore…

  13. Culturally Sustaining Pedagogy: A Needed Change in Stance, Terminology, and Practice

    ERIC Educational Resources Information Center

    Paris, Django

    2012-01-01

    Seventeen years ago Gloria Ladson-Billings (1995) published the landmark article "Toward a Theory of Culturally Relevant Pedagogy," giving a coherent theoretical statement for resource pedagogies that had been building throughout the 1970s and 1980s. I, like countless teachers and university-based researchers, have been inspired by what it means…

  14. "Does Broca's Area Exist?:" Christofredo Jakob's 1906 Response to Pierre Marie's Holistic Stance

    ERIC Educational Resources Information Center

    Tsapkini, Kyrana; Vivas, Ana B.; Triarhou, Lazaros C.

    2008-01-01

    In 1906, Pierre Marie triggered a heated controversy and an exchange of articles with Jules Dejerine over the localization of language functions in the human brain. The debate spread internationally. One of the timeliest responses, that appeared in print 1 month after Marie's paper, came from Christofredo Jakob, a Bavarian-born neuropathologist…

  15. Of risks and regulations: how leading U.S. nanoscientists form policy stances about nanotechnology.

    PubMed

    Corley, Elizabeth A; Scheufele, Dietram A; Hu, Qian

    2009-10-01

    Even though there is a high degree of scientific uncertainty about the risks of nanotechnology, many scholars have argued that policy-making cannot be placed on hold until risk assessments are complete (Faunce, Med J Aust 186(4):189-191, 2007; Kuzma, J Nanopart Res 9(1):165-182, 2007; O'Brien and Cummins, Hum Ecol Risk Assess 14(3):568-592, 2008; Powell et al., Environ Manag 42(3):426-443, 2008). In the absence of risk assessment data, decision makers often rely on scientists' input about risks and regulation to make policy decisions. The research we present here goes beyond the earlier descriptive studies about nanotechnology regulation to explore the heuristics that the leading U.S. nanoscientists use when they make policy decisions about regulating nanotechnology. In particular, we explore the relationship between nanoscientists' risk and benefit perceptions and their support for nanotech regulation. We conclude that nanoscientists are more supportive of regulating nanotechnology when they perceive higher levels of risks; yet, their perceived benefits about nanotechnology do not significantly impact their support for nanotech regulation. We also find some gender and disciplinary differences among the nanoscientists. Males are less supportive of nanotech regulation than their female peers and materials scientists are more supportive of nanotechnology regulation than scientists in other fields. Lastly, our findings illustrate that the leading U.S. nanoscientists see the areas of surveillance/privacy, human enhancement, medicine, and environment as the nanotech application areas that are most in need of new regulations. PMID:21170136

  16. Argumentative stance and political faith healing: “The dream will come true”

    Microsoft Academic Search

    Richard E. Crable; Steven L. Vibbert

    1983-01-01

    This essay analyzes President Ronald Reagan's speech “On Our Economic Recovery” as a means of exploring the argumentative resources of political faith healing. By exploiting the illocutionary ambiguity of “shall” and “must,” the faith healer as rhetor permits a state of healing to be seen as either prediction or command. By strategic identification and division, faith healers—both mystical and political—can

  17. "Working with" as a Methodological Stance: Collaborating with Students in Teaching, Writing, and Research

    ERIC Educational Resources Information Center

    Siry, Christina A.; Zawatski, Elizabeth

    2011-01-01

    Using critical ethnography guided by cultural sociology, this paper examines the role of "co" in teacher education; coresearching, coteaching, and cogenerating dialogue. The authors are a pre-service teacher and a college instructor, and through our multiple perspectives and positionings, we explore how collaboration served to dismantle…

  18. Designing Worked Examples in Statics to Promote an Expert Stance: Working THRU vs. Working OUT

    ERIC Educational Resources Information Center

    Calfee, Robert; Stahovich, Thomas

    2011-01-01

    The purpose of this study was to examine the performance patterns of freshman engineering students as they completed a tutorial on freebody problems that employed a computer-based pen (CBP) to provide feedback and direct learning. A secondary analysis was conducted on detailed performance data for 16 participants from a freshman Engineering course…

  19. Genetic counseling and the disabled: feminism examines the stance of those who stand at the gate.

    PubMed

    Patterson, Annette; Satz, Martha

    2002-01-01

    This essay examines the possible systematic bias against the disabled in the structure and practice of genetic counseling. Finding that the profession's "nondirective" imperative remains problematic, the authors recommend that methodology developed by feminist standpoint epistemology be used to incorporate the perspective of disabled individuals in genetic counselors' education and practice, thereby reforming society's view of the disabled and preventing possible negative effects of genetic counseling on the self-concept and material circumstance of disabled individuals. PMID:14682342

  20. Lateral orientation and stabilization of human stance: static versus dynamic visual cues

    Microsoft Academic Search

    B. Amblard; J. Crémieux; A. R. Marchand; A. Carblanc

    1985-01-01

    The differential contributions of static versus dynamic visual cues to postural control were studied in human subjects. Lateral body oscillations were measured with accelerometers located at head, hips and ankle levels, while subjects righted their balance under various mechanical conditions: i) on either a soft (foam rubber) support or a hard one, and ii) in either the classical or the

  1. Is gender inclusivity an answer to ethical issues in business? An Indian stance

    Microsoft Academic Search

    Suveera Gill

    2010-01-01

    Purpose – If females are more ethical than males, as the literature on the subject generally suggests, engaging and encouraging females in their careers would certainly promote an ethical environment. The present paper is motivated by such a viewpoint and aims to investigate gender-based differences in the ethical disposition and the underlying dimensions in ethical decision-making processes, by specific examination

  2. European definitions, current use, and EMA stance of platelet-rich plasma in sports medicine.

    PubMed

    Fiorentino, Stefano; Roffi, Alice; Filardo, Giuseppe; Marcacci, Maurilio; Kon, Elizaveta

    2015-02-01

    Platelet-rich plasma has been the focus of much attention over the last few years as an appealing biological approach to favor the healing of tissues otherwise doomed by a low healing potential. In Europe, the regulatory framework concerning the blood system is currently disciplined by Directive 2002/98/EC of the European Parliament and Council of January 27, 2003, which sets out quality and safety rules for collecting, controlling, processing, preserving, and distributing human blood and its components, acknowledged in the various States of the Union with internal regulations. This lack of homogeneity in the European legal landscape will probably lead the Community legislature to intervene in the near future, to even out the "rules of engagement" of this peculiar class of biomaterials. PMID:25419835

  3. Taking a Stance through Visual Texts: Novice Teachers as Educational Agents

    ERIC Educational Resources Information Center

    Orland-Barak, Lily; Maskit, Ditza

    2014-01-01

    Drawing on qualitative methodologies that integrate verbal and non-verbal texts, this study investigated novice teachers' attributions of their experiences of internship, as conveyed through a visual text. Novices were invited to design a visual text that represented their experience during internship, as part of a national call entitled…

  4. Teachers' Stances and Practical Arguments regarding a Science-Indigenous Knowledge Curriculum: Part 1

    ERIC Educational Resources Information Center

    Ogunniyi, M. B.

    2007-01-01

    The new South African curriculum known as Curriculum 2005 (to depict the year of its full implementation) requires that teachers integrate school science with Indigenous Knowledge Systems (IKS). Curriculum 2005 has generated heated debates at various levels since its inception in 1997. This study focuses on the effectiveness or otherwise of a…

  5. Ideologies of Violence: A Corpus and Discourse Analytic Approach to Stance in Threatening Communications

    ERIC Educational Resources Information Center

    Gales, Tammy Angela

    2010-01-01

    This authentic threat asserts impending fatal injury. Because of the dangerous nature of threats, investigators must immediately ask: Is the intent real? Is the threatener likely to act? With real lives at risk, using the linguistic information available to answer these questions quickly and accurately is of great importance. Yet, because most…

  6. Athlete support personnel and anti-doping: Knowledge, attitudes, and ethical stance.

    PubMed

    Mazanov, J; Backhouse, S; Connor, J; Hemphill, D; Quirk, F

    2014-10-01

    Athlete support personnel (ASP) failing to meet responsibilities under the World Anti-Doping Code risk sanction. It is unclear whether the poor knowledge of responsibilities seen in sports physicians and coaches applies to other ASP (e.g., administrators, chiropractors, family, nutritionists, physiotherapists, psychologists, and trainers). A purposive sample of Australian ASP (n?=?292) responded to a survey on knowledge of anti-doping rules (35 true/false questions), ethical beliefs and practice, and attitudes toward performance enhancement. Some ASP declined to participate, claiming doping was irrelevant to their practice. Physicians were most knowledgeable (30.8/35), with family and trainers the least (26.0/35). ASP reported that improvements were needed to support anti-doping education (e.g., basis for anti-doping) and practice (e.g., rules). ASP also had a slightly negative attitude toward performance enhancement. Linear regression showed that being a sports physician, providing support at the elite level, and 15 years of experience influenced knowledge. The results confirm gaps in knowledge, suggesting that stronger engagement with ASP anti-doping education and practice is needed. Applying the principles of andragogy could help foster active engagement through emphasis on active inquiry, rather than passive reception of content. Future work on the context within which ASP experience anti-doping is needed, exploring acquisition and translation of knowledge into practice. PMID:23692367

  7. Causality vs. Plausibility: Alternative Stances for Inquiry into Human Behavior. Draft.

    ERIC Educational Resources Information Center

    Guba, Egon G.; Lincoln, Yvonna S.

    Arguing that the concept of causality in human experience is archaic, unnecessary, and misleading, particularly in the social/behavioral sciences, a new plausibility approach is proposed for understanding relationships among entities. The epistemological history of causality includes positivist, deductive-nomological, essentialist, activity or…

  8. Epistemic, interpersonal, and moral stances in the construction of us and them in Christian metal lyrics

    Microsoft Academic Search

    Henna Jousmäki

    2011-01-01

    Religious groupings and subcultures both tend to have well-articulated interests, aims, and values that unite certain people but also alienate those who do not share their interests. The case is then made for the construction of difference between ‘us’ and ‘them’. This paper examines the construction of such a group boundary in the previously little studied context of the Christian

  9. Is the Personal Political? Chronotopes and Changing Stances toward Catalan Language and Identity

    ERIC Educational Resources Information Center

    Woolard, Kathryn A.

    2013-01-01

    During the early catalanization of schooling in the Barcelona area in the 1980s, Castilian-speaking teenagers of working-class immigrant descent often struggled against Catalan language and identity. This longitudinal study followed a group of high-school classmates and found that as young adults, some but not all of the resistant working-class…

  10. The effects of the proximity of an object on human stance

    Microsoft Academic Search

    Cédrick T. Bonnet; Jean-Jacques Temprado; Eric Berton

    2010-01-01

    The present study tested the possibility that center of pressure (COP) behaviour is changed because of the proximity of an object (visible or not) from the body. Main effects of distance were expected for COP sway and main effects of location were expected for COP position when the object stands within a security margin (four centimetres; near distance) and within

  11. Taking a Diasporic Stance: Puerto Rican Mothers Educating Children in a Racially Integrated Neighborhood

    ERIC Educational Resources Information Center

    Rolon-Dow, Rosalie

    2010-01-01

    This article presents the perspectives of second-generation Puerto Rican mothers as they discuss their experiences educating their children in a working class, lower-middle class, racially diverse neighborhood. The article examines the racialization processes that the women and their families face, despite experiencing geographic and socioeconomic…

  12. APPS’s stance on self-plagiarism: Just say no1

    PubMed Central

    Culley, Theresa M.

    2014-01-01

    Should authors be able to reuse the same text in multiple papers without citing the earlier source? Known as self-plagiarism, this practice is strongly discouraged in Applications in Plant Sciences (APPS) because it violates professional standards, is potentially deceptive, and lacks originality. The most frequent form of self-plagiarism in APPS submissions is text recycling, which depending on the extent and location of copied text, has consequences ranging from authors being required to rewrite duplicated text or add citations, to automatic rejection of a manuscript without review. Ultimately, avoidance of self-plagiarism will result in original articles that improve upon, and do not simply replicate, the existing literature. PMID:25202643

  13. Unilateral lower limb muscle fatigue induces bilateral effects on undisturbed stance and muscle EMG activities.

    PubMed

    Berger, L L; Regueme, S C; Forestier, N

    2010-10-01

    The study investigated the effects of an unilateral ankle muscle fatigue onto independent postural control parameters including the trajectories of the estimated resultant CoP (CoPres) and his components: the centre of gravity (CG) and CoP-CG trajectories. Nine healthy men realized series of 10 toe-lift immediately followed by 10 knee flexions until exhaustion with one (Ex) leg. Maximal isometric voluntary contractions, postural sway measures of each leg, and muscular activities of the ankle muscles were recorded before and immediately after the fatiguing exercise. As expected, the latter induced a decrease in maximal voluntary peak force associated with a greater variability of the relative contribution of each leg on the CoPres, enhanced all postural parameters of the non-exercised leg. A significant decreased of the tibialis anterior EMG activity for the Ex leg and an increased one for the NoEx leg. Finally, following unilateral fatigue, the body sway destabilisation seemed to occur only along the medio-lateral (ML) axis. The enhanced and greater variability of the variance along ML axis might be explained by the recourse at the loading-unloading strategy choice and suggests a central attempt to compensate for pain sensation. PMID:19879160

  14. An intentional stance modulates the integration of gesture and speech during comprehension

    Microsoft Academic Search

    Spencer D. Kelly; Sarah Ward; Peter Creigh; James Bartolotti

    2007-01-01

    The present study investigates whether knowledge about the intentional relationship between gesture and speech influences controlled processes when integrating the two modalities at comprehension. Thirty-five adults watched short videos of gesture and speech that conveyed semantically congruous and incongruous information. In half of the videos, participants were told that the two modalities were intentionally coupled (i.e., produced by the same

  15. Teachers' Stances on Cell Phones in the ESL Classroom: Toward a "Theoretical" Framework

    ERIC Educational Resources Information Center

    Brown, Jeff

    2014-01-01

    In the ongoing and constantly expanding discussion surrounding cell phones in the classroom, a theoretical complement to the practical side of the issue is generally lacking. This is perhaps understandable. Many teachers are still trying to deal with the simple presence of cell phones in the class, and managing a classroom in which the presence…

  16. Extensive expertise in endocrinology: UK stance on adult GH replacement: the economist vs the endocrinologist.

    PubMed

    Shalet, S M

    2013-10-01

    In the UK, through the use of a forced economic model, endocrinologists are in the curious position of offering GH replacement to some patients with severe GH deficiency (GHD) but withholding it from other patients with even more severe GHD. This approach is counter-intuitive to endocrine practice in treating endocrine deficiency states. For all other endocrine deficiencies, one would opt for treating those with the most severe biochemical evidence of deficiency first. If this endocrine approach was applied to adult GH replacement in an era of rationing, one would start with the GHD patients with a pathologically low IGF1 level. Given that the prevalence of subnormal IGF1 levels in a GHD population is age-dependent, this would result in GH replacement being offered to more young adult onset (AO) GHD and childhood onset GHD adults, and less often to middle-aged and elderly AO GHD adults. This in itself has the added advantage that the skeletal benefits appear more real in the former cohort of patients. PMID:23904274

  17. Cultivating an Inquiry Stance in English Education: Rethinking the Student Teaching Seminar

    ERIC Educational Resources Information Center

    Meyer, Tom; Sawyer, Mary

    2006-01-01

    We argue that the student teaching seminar, a co-requisite to student teaching, may best be construed as a "first" introduction to a teacher learning community and to inquiry-oriented professional development. Using a qualitative case study design and discourse analysis, we examine 60 "Teaching Inquiries" (TIs) occurring in student teaching…

  18. Developing an Anti-Racist Stance: How White Youth Understand Structural Racism

    Microsoft Academic Search

    Catharine R. Thomann

    2011-01-01

    Racism continues to be a formidable and pressing problem. While racism can take many forms, and overt, legally sanctioned acts of racism have declined, structural racism continues to persist. Structural racism encompasses both institutional racism and the broader effects of social racism. White allies--White individuals committed to using their unearned power and privilege to work to dismantle racism--can play a

  19. Mastering Academic Language: Organization and Stance in the Persuasive Writing of High School Students

    ERIC Educational Resources Information Center

    Uccelli, Paola; Dobbs, Christina L.; Scott, Jessica

    2013-01-01

    Beyond mechanics and spelling conventions, academic writing requires progressive mastery of advanced language forms and functions. Pedagogically useful tools to assess such language features in adolescents' writing, however, are not yet available. This study examines language predictors of writing quality in 51 persuasive essays produced by high…

  20. "By the Rivers of Babylon": Deterritorialization and the Jewish Rhetorical Stance

    ERIC Educational Resources Information Center

    Bernard-Donals, Michael

    2010-01-01

    The position of the excluded other, it seems to the author, is the position that has characterized Jews since antiquity: exiled from the nation and dispersed to other nations, Jewish participation in civic life has been defined, even in modernity, by its marginalization and precariousness. The Jew, in other words, provides a salient example of the…

  1. Interaction between task demands and surface properties in the control of goal-oriented stance

    Microsoft Academic Search

    Ludovic Marin; Bernard Baumberger; Michelangelo Flückiger; Thomas A Stoffregen

    1999-01-01

    Standing subjects were asked to track the fore-aft motion of a target with their heads. Three support surface conditions (standard, foam, rollers) were crossed with three amplitudes of target motion. The relative phase ?rel between angular motion of ankles and hips was analyzed. Two preferred patterns emerged; close to in-phase (?rel?0°), and close to anti-phase (?rel?180°). On the solid surface

  2. Yes-No Questions that Convey a Critical Stance in the Language Classroom

    ERIC Educational Resources Information Center

    Waring, Hansun Zhang

    2012-01-01

    Despite certain important critiques, much of the work on teacher questions has centered on the distinction between referential and display questions as well as their roles in creating more or less communicative classrooms. With some notable exceptions, few have delved into the specificity of how questions work in the details of classroom…

  3. A Group of Educators' Stance on the Implementation of South Africa's Further Education and Training Curriculum

    ERIC Educational Resources Information Center

    Treu, P.; Olivier, M. A. J.; Bean, P.; Van der Walt, J. L.

    2010-01-01

    In their dealings with educators in the Southern Cape region of South Africa, the researchers observed among them a degree of negativity and pessimism about the implementation of the Further Education and Training (FET) policy and curriculum during 2006. Exploratory discussions supported the surmise that a gap existed between policy formulation…

  4. A Theory of Timed Automata

    Microsoft Academic Search

    Rajeev Alur

    1994-01-01

     We propose timed (finite) automata to model the behavior of realtime systems over time. Our definition provides a simple, and yet powerful, way to annotate state-transition graphs with timing constraints using finitely many realvalued clocks . A timed automaton accepts timed words --- infinite sequences in which a real-valued time of occurrence is associated with each symbol. We study timed

  5. Time and Learning. ERIC Digest.

    ERIC Educational Resources Information Center

    Metzker, Bill

    The use of time in school is undergoing close scrutiny. Over the years, educators have sought to enhance learning time through such reforms as block scheduling and year-round schools. School time can be conceived as an inverted pyramid, in which allocated time (total time in the school day or year) forms the top tier, engaged time (time-on-task)…

  6. Timing, remembering, and discrimination.

    PubMed

    Sargisson, Rebecca J; White, K Geoffrey

    2007-01-01

    Four pigeons were first trained in a timing procedure. In one condition, each trial began with the presentation of an X on the center key, followed by a delay (short or long), after which two side keys were lit. If the delay was short, pecks to the red side key were reinforced. If the delay was long, pecks to the green side key were reinforced. In a second condition, the opposite contingencies applied following presentation of a square on the center key. Choice responses were then tested at 10 time intervals ranging from short to long (1 to 4 s and 4 to 7 s in different conditions). The two timing conditions were combined to create a remembering condition in which correct responding depended upon discrimination of both the sample stimulus (X or square) and the delay interval (short or long). Choices varied systematically across delay in timing conditions, but in remembering conditions, accurate choice at the training delays did not initially generalize to intermediate delays. However, with prolonged training in the remembering task, the response pattern began to resemble that of the timing conditions. Generalization gradients were asymmetrical, in accordance with Weber's Law, in that greater generalization occurred with longer delays than with shorter delays. PMID:17345949

  7. Discrete-Time Goldfishing

    NASA Astrophysics Data System (ADS)

    Calogero, Francesco

    2011-08-01

    The original continuous-time ''goldfish'' dynamical system is characterized by two neat formulas, the first of which provides the N Newtonian equations of motion of this dynamical system, while the second provides the solution of the corresponding initial-value problem. Several other, more general, solvable dynamical systems ''of goldfish type'' have been identified over time, featuring, in the right-hand (''forces'') side of their Newtonian equations of motion, in addition to other contributions, a velocity-dependent term such as that appearing in the right-hand side of the first formula mentioned above. The solvable character of these models allows detailed analyses of their behavior, which in some cases is quite remarkable (for instance isochronous or asymptotically isochronous). In this paper we introduce and discuss various discrete-time dynamical systems, which are as well solvable, which also display interesting behaviors (including isochrony and asymptotic isochrony) and which reduce to dynamical systems of goldfish type in the limit when the discrete-time independent variable l=0,1,2,... becomes the standard continuous-time independent variable t, 0?t

  8. Discrete-Time Goldfishing

    E-print Network

    Calogero, Francesco

    2011-01-01

    The original continuous-time "goldfish" dynamical system is characterized by two neat formulas, the first of which provides the $N$ Newtonian equations of motion of this dynamical system, while the second provides the solution of the corresponding initial-value problem. Several other, more general, solvable dynamical systems "of goldfish type" have been identified over time, featuring, in the right-hand ("forces") side of their Newtonian equations of motion, in addition to other contributions, a velocity-dependent term such as that appearing in the right-hand side of the first formula mentioned above. The solvable character of these models allows detailed analyses of their behavior, which in some cases is quite remarkable (for instance isochronous or asymptotically isochronous). In this paper we introduce and discuss various discrete-time dynamical systems, which are as well solvable, which also display interesting behaviors (including isochrony and asymptotic isochrony) and which reduce to dynamical systems ...

  9. Agency, time, and causality

    PubMed Central

    Widlok, Thomas

    2014-01-01

    Cognitive Scientists interested in causal cognition increasingly search for evidence from non-Western Educational Industrial Rich Democratic people but find only very few cross-cultural studies that specifically target causal cognition. This article suggests how information about causality can be retrieved from ethnographic monographs, specifically from ethnographies that discuss agency and concepts of time. Many apparent cultural differences with regard to causal cognition dissolve when cultural extensions of agency and personhood to non-humans are taken into account. At the same time considerable variability remains when we include notions of time, linearity and sequence. The article focuses on ethnographic case studies from Africa but provides a more general perspective on the role of ethnography in research on the diversity and universality of causal cognition. PMID:25414683

  10. Time and Tachyon

    NASA Astrophysics Data System (ADS)

    Sen, Ashoke

    Recent analysis suggests that the classical dynamics of a tachyon on an unstable D-brane is described by a scalar Born Infeld type action with a runaway potential. The classical configurations in this theory at late time are in one to one correspondence with the configuration of a system of noninteracting (incoherent), nonrotating dust. We discuss some aspects of canonical quantization of this field theory coupled to gravity, and explore, following an earlier work on this subject, the possibility of using the scalar field (tachyon) as the definition of time in quantum cosmology. At late "time" we can identify a subsector in which the scalar field decouples from gravity and we recover the usual Wheeler de Witt equation of quantum gravity.

  11. The Earth Times

    NSDL National Science Digital Library

    The Earth Times is an "independent, international, nonpartisan newspaper focusing on environment and sustainable development, and such interrelated concerns of the international system as population, human rights, trade, and women's and children's rights." It is specifically aimed at opinion and policy makers, community and business leaders, nongovernmental organizations, and students and teachers. It was founded in 1991 by Pranay Gupte, a columnist for Newsweek International and a former foreign correspondent for The New York Times. The newspaper form of the Earth Times is available by subscription. Students and teachers in the US can receive it free upon request. The website offers two feature articles from the current issue and all articles from back issues. Articles can be searched for keywords; however, the web version only includes issues going back to June of 1996.

  12. Real-Time Simulation

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Coryphaeus Software, founded in 1989 by former NASA electronic engineer Steve Lakowske, creates real-time 3D software. Designer's Workbench, the company flagship product, is a modeling and simulation tool for the development of both static and dynamic 3D databases. Other products soon followed. Activation, specifically designed for game developers, allows developers to play and test the 3D games before they commit to a target platform. Game publishers can shorten development time and prove the "playability" of the title, maximizing their chances of introducing a smash hit. Another product, EasyT, lets users create massive, realistic representation of Earth terrains that can be viewed and traversed in real time. Finally, EasyScene software control the actions among interactive objects within a virtual world. Coryphaeus products are used on Silican Graphics workstation and supercomputers to simulate real-world performance in synthetic environments. Customers include aerospace, aviation, architectural and engineering firms, game developers, and the entertainment industry.

  13. Time and language.

    PubMed

    Scharf, J H

    1982-01-01

    It is very interesting question whether time if a priori in mankind's thinking or whether it is a category which results from experience. Each human being has a memory so that he is able to distinguish between the past and the present, but not every language has a word expressing the common idea of time. In hunting and gathering populations such as Bushmen and Yumbri no one can state his own age. In chronobiology, the most important zeitgebers are the sun and the moon. Certain peasant peoples, such as the Santals and Mundas in India, even today use the same word to express sun, Sun-God, daylight, day, day-time, and hour. The first generalized idea of "time" seems to have arisen in the civilization of Old Mesopotamia. While the general meaning was still unknown to Sumerian, Accadian priest-astronomers presumably created the conception by generalization of the (Sumerian) foreign word itu(d) "mouth" and its mingling with the Accadian ittu(m) "sign (as an eclipse, monstrous birth, etc.), term, moment". We find the same root in the Etruscan itus "ides" from which it came as a loan-word into Latin (idus "ides"). Newton's term duratio can be found in earliest Iranian as yav- "yoke" and Vedic Indian as yugam "yoke" (i.e., a "bound" time). Some remarks are made concerning mankind's earliest chronobiological thinking where menstruation serves as a model. West African Kwa languages (predominantly Ewe), Old Indian, and early-classical chinese are evaluated. A brief survey is given of prehistoric peoples' migrations in terms of languages. The presentation concludes with an attempt to define time as an abstraction of abstractions, a fussy set (of ideas and definitions) in terms of post-classical set theory. PMID:7129063

  14. Shifting Times Tables

    NSDL National Science Digital Library

    This activity provides students with an opportunity to recognize arithmetic sequences and at the same time reinforces identifying multiples. The interactivity displays five numbers and the student must discover the times table pattern and the numerical shift. On Levels 1 and 2, the first five numbers in the sequence are given and on Levels 3 and 4, the numbers given could be any five numbers in the sequence. The Teachers' Notes page offers rationale, suggestions for implementation, discussion questions, ideas for extension and support.

  15. Times for interplanetary trips

    NASA Technical Reports Server (NTRS)

    Jones, R. T.

    1976-01-01

    The times required to travel to the various planets at an acceleration of one g are calculated. Surrounding gravitational fields are neglected except for a relatively short distance near take-off or landing. The orbit consists of an essentially straight line with the thrust directed toward the destination up to the halfway point, but in the opposite direction for the remainder so that the velocity is zero on arrival. A table lists the approximate times required, and also the maximum velocities acquired in light units v/c for the various planets.

  16. Interactive Telling Time Lite

    NSDL National Science Digital Library

    GiggleUp Kids Apps And Educational Games Pty Ltd

    2013-09-16

    This iOS app allows learners to practice reading both a digital and analog clock. Learners can choose between either "Set the Time" or "Stop the Clock" games. In the first game players move the hour and/or minute hand to show the target time. In the second game players stop the clock on the exact minute and hour described. Two versions of the clock are available in the lite version of the app. Additional clocks and games are available with upgrade to full version ($) of the app.

  17. Decoherence and time emergence

    E-print Network

    A. Camacho

    1998-07-30

    In this work the possible role that Decoherence Model could play in the emergence of the classical concept of time is analyzed. We take the case of a Mixmaster universe with small anisotropy and construct its Halliwell propagator. Afterwards we introduce in our system terms that comprise the effects of Decoherence Model. This is done by means of the so called Restricted Path Integral Formalism. We obtain Halliwell's modified propagator and find that a gauge invariant physical time emerges as consequence of this process.

  18. New York Times: Circuits

    NSDL National Science Digital Library

    Circuits is a new New York Times weekly offering intended to enhance the newspaper's technology coverage. It contains regular gaming and computer columns, along with an eclectic mix of articles and essays that address in a general way the interaction between humans and technology. The first three issues contained articles on where computers go to die, music and jobs on the web, computer games for girls, online auctions, home theatre, web TV, and computer ergonomics, among others. At present, Circuit archives are available. Note that the New York Times is freely available (after required registration) to users in the US.

  19. The Geologic Time Scale

    NSDL National Science Digital Library

    This site contains a large, easy to read, detailed geologic time scale for the Phanerozoic Eon (544 million years ago - Present). This is the period of time, also known as an eon, between the end of the Precambrian and today. The Phanerozoic begins with the start of the Cambrian period, 544 million years ago. It encompasses the period of abundant, complex life on Earth. The chart includes the Era, Period or System, and the Epoch or Series and features a brief description of each.

  20. Time, Chance, and Reduction

    NASA Astrophysics Data System (ADS)

    Ernst, Gerhard; Hüttemann, Andreas

    2010-01-01

    List of contributors; 1. Introduction Gerhard Ernst and Andreas Hütteman; Part I. The Arrows of Time: 2. Does a low-entropy constraint prevent us from influencing the past? Mathias Frisch; 3. The part hypothesis meets gravity Craig Callender; 4. Quantum gravity and the arrow of time Claus Kiefer; Part II. Probability and Chance: 5. The natural-range conception of probability Jacob Rosenthal; 6. Probability in Boltzmannian statistical mechanics Roman Frigg; 7. Humean mechanics versus a metaphysics of powers Michael Esfeld; Part III. Reduction: 8. The crystallisation of Clausius's phenomenological thermodynamics C. Ulises Moulines; 9. Reduction and renormalization Robert W. Batterman; 10. Irreversibility in stochastic dynamics Jos Uffink; Index.

  1. Funding Full-Time Study through Part-Time Work

    ERIC Educational Resources Information Center

    Richardson, Mark; Evans, Carl; Gbadamosi, Gbolahan

    2009-01-01

    Full-time students engaged in part-time studies have been a subject of increasing academic attention. This study extends work in this area by examining: the extent to which full-time undergraduate students undertake part-time employment, the reasons for working whilst studying full-time and the extent to which students relate their part-time

  2. Time Stamp Students Page 1 Using time Information Management (TIM)

    E-print Network

    Crews, Stephen

    Time Stamp Students Page 1 Using time Information Management (TIM) Time Stamp Employees University of North Carolina at Chapel Hill University of North Carolina Time Information Management (TIM) EPA Exempt Employees Using Time Information Management (TIM) Time EPA Employees are Exempt and paid on a Salary basis

  3. Space-time diagrammatics

    E-print Network

    Piotr T. Chru?ciel; Christa R. Ölz; Sebastian J. Szybka

    2013-01-20

    We introduce a new class of two-dimensional diagrams, the \\emph{projection diagrams}, as a tool to visualize the global structure of space-times. We construct the diagrams for several metrics of interest, including the Kerr-Newman - (anti) de Sitter family, with or without cosmological constant, and the Emparan-Reall black rings.

  4. Borrowed Traits, Borrowed Time

    Microsoft Academic Search

    JADE TAKAKUWA

    Every time you look into the mirror, you see history in its purest form. The curve of the nose, the shape of the eye, the hair on the head—everything represents a path that has been traveled and a choice that has been made. But this choice was not made by you, but by those infinitesimal strands of mate- rial that

  5. The First Time

    ERIC Educational Resources Information Center

    Black, Beth

    2011-01-01

    In this article, the author narrates her experience of meeting a Montessori kid for the first time and shares the characteristics she observed in Montessori students. The author was working as director of academic resources in university housing at the University of Wisconsin-Madison and met Jason, a pre-med sophomore who was the resident…

  6. Distance Rate Time

    NSDL National Science Digital Library

    National Science Digital Library (NSDL) Middle School Portal Staff

    2008-03-10

    Measurement is one of the core NCTM Principals and Standards for School Mathematics content standards, and rate is central to its practical application. While most middle school students know the distance-rate-time formula, they may still benefit from a closer study of the relationship through these online resources.

  7. Saving Time with Technology

    ERIC Educational Resources Information Center

    Gullen, Kristine; Zimmerman, Holly

    2013-01-01

    In order to help teachers envision digital products in action in classrooms, the authors look at three examples of how teachers they know enhance learning time by employing technology efficiently. The examples include: (1) a social studies teacher who begins each class period with a three-question formative assessment using the website…

  8. When Time Counts

    Microsoft Academic Search

    Nicholas Mazza; Barbara D. Price

    1985-01-01

    Poetry, music and time used as therapeutic agents in short-term (seven sessions) group treatment are especially helpful in working with depressed college students. They provide a means to reduce dependency and establish boundaries compatible with agency limitations. Specific poetic techniques include (a) sharing a preexisting poem or song and inviting reactions; (b) construction of a group of collaborative poems. Further

  9. Time, love and Species

    Microsoft Academic Search

    Takaomi Sakai; Norio Ishida

    2001-01-01

    Physiological and behavioral phenomena of many animals are restricted to certain times of the day. Many organisms show daily rhythms in their mating. The daily fl uctuation in mating activity of a few insects is controlled by an endogenous clock. The fruitfl y, Drosophila, is the most suitable mate- rial to characterize the genetic basis of circadian rhythms of mating

  10. The time travel paradox

    E-print Network

    S. Krasnikov

    2002-03-27

    We define the time travel paradox in physical terms and prove its existence by constructing an explicit example. We argue further that in theories -- such as general relativity -- where the spacetime geometry is subject to nothing but differential equations and initial data no paradoxes arise.

  11. Time in quantum mechanics

    E-print Network

    Chapin, Kimberly R.

    1997-01-01

    in this problem because [H-system] and [ ] were found to commute. Pauli's objection was based on the fact that the commutator relation of [H-system] and [ ] was equal to an unit of action. Finally, interpreting [ ] as a time of motion, the analog of the lifetime...

  12. The Time of Surak

    E-print Network

    Multiple Contributors

    1979-01-01

    &ipA: Maty Stacy-MacVonald 27 Not Quite the Way History Recalls It illocd by Melody FKamc Terrance Oswald Knova 101 Starships of the Eldar? Maggie Nowakowska title illo by Pam KowaJUki. lettering layout by Amy Falkowitz HZ Time of Surak Randy William Ash...

  13. LIGHT, TIME AND MICROORGANISMS

    Microsoft Academic Search

    JOHN F. ALLEN

    1998-01-01

    Direct, individual human experience of the natural world can be measured in milliseconds or in decades. Our evolving picture of the world depends upon comparison of our individual experience with those of other people, which extends the time-scale, upwards, by perhaps a factor of a thousand. Thus rare astronomical and geophysical events, which most people never witness, are important ingredients

  14. Time and games

    Microsoft Academic Search

    Benjamin Leperchey

    2005-01-01

    We add the notion of time to denotational models of the - calculus. The denotation is no longer constant through reduction, but rather decreases with respect to an appropriate order. Categorically, we use a monad over a cartesian category, an order over the morphisms of the Kleisli category, and a Galois connection to model -reduction. We dene a generic monad

  15. Time-Encoded Imagers.

    SciTech Connect

    Marleau, Peter; Brubaker, Erik

    2014-11-01

    This report provides a short overview of the DNN R&D funded project, Time-Encoded Imagers. The project began in FY11 and concluded in FY14. The Project Description below provides the overall motivation and objectives for the project as well as a summary of programmatic direction. It is followed by a short description of each task and the resulting deliverables.

  16. Time and Tachyon

    Microsoft Academic Search

    Ashoke Sen

    2003-01-01

    Recent analysis suggests that the classical dynamics of a tachyon on an unstable D-brane is described by a scalar Born Infeld type action with a runaway potential. The classical configurations in this theory at late time are in one to one correspondence with the configuration of a system of noninteracting (incoherent), nonrotating dust. We discuss some aspects of canonical quantization

  17. Time and Seasons Calendar

    NSDL National Science Digital Library

    TERC

    2010-01-01

    This website contains links to 12 calendars (12 months). December contains seven activities about math with time and seasons. For instance, children find out when the sun set today, rate their day, and find out how many days until school vacation. Works as a handout, take-home, or group activity. Available as a downloadable pdf and in Spanish.

  18. Time in Cosmology

    E-print Network

    R. Brout; R. Parentani

    1999-02-05

    The notion of time in cosmology is revealed through an examination of transition matrix elements of radiative processes occurring in the cosmos. To begin with, the very concept of time is delineated in classical physics in terms of correlations between the succession of configurations which describe a process and a standard trajectory called the clock. The total is an isolated system of fixed energy. This is relevant for cosmology in that the universe is an isolated system which we take to be homogeneous and isotropic. Furthermore, in virtue of the constraint which arises from reparametrization invariance of time, it has total energy zero. Therefore the momentum of the scale factor is determined from the energy of matter. In the quantum theory this is exploited through use of the WKB approximation for the wave function of the scale factor, justified for a large universe. The formalism then gives rise to matrix elements describing matter processes. These are shown to take on the form of usual time dependent quantum amplitudes wherein the temporal dependence is given by a background which is once more fixed by the total energy of matter.

  19. Leadership in Challenging Times

    ERIC Educational Resources Information Center

    City, Elizabeth A.

    2013-01-01

    In spite of tough financial times, resourceful school leaders devise ways to overcome challenges and improve education. To do this, they make strategic use of the resources they have. And they also cultivate learning communities. In this article, Elizabeth A. City describes how school leaders can make more strategic use of three essential…

  20. Pulsar Searching and Timing

    NASA Astrophysics Data System (ADS)

    Manchester, R. N.

    2013-01-01

    More than 2000 pulsars are now known. These pulsars may be divided into a number of different classes according to their period, period derivative, binary properties, emission characteristics and so on. Some important classes have relatively few members, e.g. double-neutron-star binary systems, and so continued searches for currently unknown pulsars are important. Such searches are being undertaken at various observatories around the world. Somewhat unexpectedly, the Fermi Gamma-ray Observatory, has proved to be an efficient pulsar detector, especially for millisecond pulsars (MSPs). The great stability of pulsar periods, especially for MSPs, leads to a number of important applications of pulsar timing. The detection and study of relativistic orbit perturbations in double-neutron-star systems has proved to be a powerful tool with measurements of the original binary pulsar, PSR B1913+16, and more recently the double pulsar, PSR J0737-3039A/B, showing that Einstein's general theory of relativity accurately describes these gravitational interactions. Direct detection of gravitational waves using pulsar timing is close to being achieved with the development of pulsar timing arrays (PTAs) in Europe, North America and Australia. Combining data from these PTAs to form the International Pulsar Timing Array (IPTA) will lead to improved significance of such a detection. Ultimately, detailed study of gravitational-wave sources will be possible using future large radio telescopes such as FAST and the SKA.

  1. This Time It's Personal

    ERIC Educational Resources Information Center

    Demski, Jennifer

    2012-01-01

    Educators have known for some time now that a one-size-fits-all approach to learning does not lead to the level of student engagement and academic success that schools strive to achieve. In their search for a more customized approach to delivering instruction, they've explored project-based learning, addressed different learning styles, and…

  2. TIMED Spacecraft Model

    NSDL National Science Digital Library

    2012-08-03

    This is a model for students to assemble, aimed at enhancing their knowledge of NASA spacecraft and scientific facts. The cover contains background information about the Thermosphere, Ionosphere, Mesosphere Energetics and Dynamics (TIMED) mission as well as two language arts activities to reinforce space science vocabulary and concepts.

  3. Decay Time of Cathodoluminescence

    ERIC Educational Resources Information Center

    Kraftmakher, Yaakov

    2009-01-01

    Simple measurements of the decay time of cathodoluminescence are described. Cathodoluminescence is used in many devices, including computer monitors, oscilloscopes, radar displays and television tubes. The experimental setup is simple and easy to build. Two oscilloscopes, a function generator, and a fast photodiode are needed for the experiments.…

  4. Hard Times Hit Schools

    ERIC Educational Resources Information Center

    McNeil, Michele

    2008-01-01

    Hard-to-grasp dollar amounts are forcing real cuts in K-12 education at a time when the cost of fueling buses and providing school lunches is increasing and the demands of the federal No Child Left Behind Act still loom larger over states and districts. "One of the real challenges is to continue progress in light of the economy," said Gale Gaines,…

  5. Time reversal communication system

    DOEpatents

    Candy, James V. (Danville, CA); Meyer, Alan W. (Danville, CA)

    2008-12-02

    A system of transmitting a signal through a channel medium comprises digitizing the signal, time-reversing the digitized signal, and transmitting the signal through the channel medium. The channel medium may be air, earth, water, tissue, metal, and/or non-metal.

  6. Budgeting in Hard Times.

    ERIC Educational Resources Information Center

    Parrino, Frank M.

    2003-01-01

    Interviews with school board members and administrators produced a list of suggestions for balancing a budget in hard times. Among these are changing calendars and schedules to reduce heating and cooling costs; sharing personnel; rescheduling some extracurricular activities; and forming cooperative agreements with other districts. (MLF)

  7. Fossils, Rocks, and Time

    NSDL National Science Digital Library

    Lucy E. Edwards

    1997-06-26

    This on-line book, published by the United States Geological Survey (USGS), discusses the use of fossils in determining the age of rocks. The publication covers how to place events in correct temporal order, a description of the geologic time scale, the use of fossils to indicate rock ages, the law of fossil succession, index fossils, and radioactive dating.

  8. Screen time and children

    MedlinePLUS

    ... screen, such as watching TV, working on a computer, or playing video games. Screen time is sedentary activity, meaning you are ... child eat while watching TV or using the computer. Do not leave the ... as family board games, puzzles, or going for a walk. Keep a ...

  9. Time invariant curvelet denoising

    Microsoft Academic Search

    Birgir Bjorn Saevarsson; Johannes R. Sveinsson; Jon Atli Benediktsson

    2004-01-01

    The purpose of this paper is to develop a method for denoising images corrupted with additive white Gaussian noise (AWGN). The noise degrades quality of the images and makes interpretations, analysis and segmentation of images harder. In the paper the use of the time invariant discrete curvelet transform for noise reduction is con- sidered. The discrete curvelet transform is a

  10. Visualizing tags over time

    Microsoft Academic Search

    Micah Dubinko; Ravi Kumar; Joseph Magnani; Jasmine Novak; Prabhakar Raghavan; Andrew Tomkins

    2006-01-01

    We consider the problem of visualizing the evolution of tags within the Flickr (flickr.com) online image sharing com- munity. Any user of the Flickr service may append a tag to any photo in the system. Over the past year, users have on average added over a million tags each week. Under- standing the evolution of these tags over time is

  11. Biophase equilibration times.

    PubMed

    Veng-Pedersen, P; Mandema, J W; Danhof, M

    1991-09-01

    Various methods for describing how quickly a drug equilibrates at the biophase are proposed. The biophase equilibration time (BET) is the time it takes the biophase drug level to reach a given percentage (p) of its predicted steady state in a drug administration that leads to a steady-state condition. The time to reach biophase equilibrium may be defined as the BET value for p = 95, and the 50% biophase equilibration time is obtained when p = 50. Biophase equilibration profiles (BEPs), obtained by plotting p versus BET, give a dynamic representation of the approach to equilibrium and may serve as an indicator of the rate of drug delivery to the biophase. A pharmacodynamic system analysis method is proposed to determine BETs and BEPs from the biophase conduction function. The approach is demonstrated using pharmacodynamic data from the CNS effect of amobarbital evaluated by an aperiodic analysis of EEG recordings. The relevance of the BET and/or BEP principles in optimal computer-controlled drug infusion, drug design, and evaluation of targeted drug delivery is discussed. Both vascular and extravascular drug administrations are considered in the analysis. PMID:1800713

  12. Organize for More Time

    ERIC Educational Resources Information Center

    Thomas, Victoria

    2006-01-01

    This article offers some organizational solutions to help teachers better manage their classrooms and their time. To assist with the room arrangement, notebooks, and file cabinets, teachers may find it helpful to use color coding. Most teachers will have more than one class to teach during the course of a day, and, perhaps, more than one course to…

  13. TIMED Spacecraft Model

    NSDL National Science Digital Library

    Students in grades 5-9 will enhance their knowledge of NASA spacecraft and scientific facts as they assemble this colorful model. The cover of this four color tri-fold contains background information about the TIMED mission as well as two language arts activities to reinforce space science vocabulary and concepts. This product is available in hardcopy and electronic formats.

  14. It's about Time.

    ERIC Educational Resources Information Center

    Krustchinsky, Rick; Larner, Nancy

    1988-01-01

    Techniques used to teach a class of seven- and eight-year-old learning-disabled students to tell time are described. Students first practiced counting by 1s and 5s around a clock with no hands before being introduced to the differing functions of the minute and hour hands. (VW)

  15. Reaction Time Sound Explanation

    NSDL National Science Digital Library

    This experiment presents auditory stimuli and requires the participant to respond after hearing target stimuli under different conditions. This experiment gives students the opportunity to determine whether their reaction times are reliably different for tasks that require slightly different decisions. This page provides guidance for faculty who wish to incorporate this activity into their classroom.

  16. Timing and throttle linkage

    SciTech Connect

    Wenstadt, T.D.; Hagen, M.W.

    1986-11-18

    This patent describes a timing throttle control for a spark ignition internal combustion engine having a fuel/air mixing device and a spark timing device. The control comprises a first pivot on the engine, a first lever mounted on the pivot and including a cam slot having a first portion which has a substantially uniform radius about the pivot and a second portion which has a non-constant radii about the first pivot. A control means is connected to the first lever to actuate the first lever about the first pivot, a second pivot on the engine in non-parallel relation to the first pivot. A second lever is mounted on the second pivot and operative to control the timing of the spark timing device, a spherical cam follower is mounted on the second lever and engaged with the cam slot. A third lever is mounted on the third pivot and operatively connected to the fuel/air mixing device. A link interconnects the first level and the third lever.

  17. Bootstrapping Time Dilation Decoherence

    E-print Network

    Cisco Gooding; William G. Unruh

    2015-03-18

    We present a general relativistic model of a spherical shell of matter with a perfect fluid on its surface coupled to an internal oscillator, which generalizes a model recently introduced by the authors to construct a self-gravitating interferometer [1]. The internal oscillator evolution is defined with respect to the local proper time of the shell, allowing the oscillator to serve as a local clock that ticks differently depending on the shell's position and momentum. A Hamiltonian reduction is performed on the system, and an approximate quantum description is given to the reduced phase space. If we focus only on the external dynamics, we must trace out the clock degree of freedom, and this results in a form of intrinsic decoherence that shares some features with a proposed "universal" decoherence mechanism attributed to gravitational time dilation [2]. We show that the proposed decoherence remains present in the (gravity-free) limit of flat spacetime, indicating that the effect can be attributed entirely to proper time differences, and thus is not necessarily related to gravity. Finally, we point out a way to bootstrap the gravitational contribution to the time dilation decoherence by including self-interaction, and comment on how this can be considered a fundamentally gravitational intrinsic decoherence effect.

  18. Changing Times, Changing Mission?

    ERIC Educational Resources Information Center

    Levin, Bernard; Perkins, James; Clowes, Darrel

    1995-01-01

    Examines data from 1980, 1985, and 1990 that measure how colleges in the Virginia Community College System (VCCS) changed their patterns of resource allocation in response to reduced resources. Shows that VCCS colleges reduced staff, utilized more part-time faculty, increased student faculty ratios and reduced expenditures. Includes 10 data tables…

  19. Time for the Sundial.

    ERIC Educational Resources Information Center

    Andrews, Tony

    1996-01-01

    Discusses the accuracy of sundials and many factors which affect their ability to measure apparent local time. Provides directions for constructing a sundial, including how to make a universal dial. Includes background information regarding other types of sundials and descriptions of notable sundials. (DDR)

  20. Swing in Time

    NSDL National Science Digital Library

    Integrated Teaching and Learning Program,

    Students examine the motion of pendulums and come to understand that the longer the string of the pendulum, the fewer the number of swings in a given time interval. They see that changing the weight on the pendulum does not have an effect on the period. They also observe that changing the angle of release of the pendulum has negligible effect upon the period.

  1. Roping Geologic Time

    NSDL National Science Digital Library

    Randall Richardson

    After having talked about the geologic time scale (Precambrian: prior to 570 Ma; Paleozoic: 570-245 Ma; Mesozoic: 245-65 Ma; Cenozoic: 65 Ma - Present), I ask for two volunteers from the class to hold a rope that is 50 feet long. I say that one end is the beginning of the Earth (4.6 billion years ago), and the other is today. I then give out 16 clothes pins and ask various students to put a cloths pin on the 'time line' at various 'geologic events'. For example, I ask them to put one where the dinosaurs died out (end of the Mesozoic). They almost invariably put it much too old (65 Ma is less than 2% of Earth history!). Then I ask them to put one on their birthday (they now laugh). Then I ask them to put one where we think hominoids (humans) evolved (~3-4 Ma), and they realize that we have not been here very long geologically. Then I ask them to put one at the end of the Precambrian, where life took off in terms of the numbers of species, etc. They are amazed that this only represents less than 15% of Earth history. Throughout the activity I have a quiz going on where the students calculate percentages of Earth History for major geologic events, and compare it to their own ages. On their time scale, the dinosaurs died only about two 'months' ago! The exercise is very effective at letting them get a sense of how long geologic time is, and how 'recently' some major geologic events happened when you consider a time scale that is the age of the earth.

  2. The Theory of Timed Automata

    Microsoft Academic Search

    Rajeev Alur

    1991-01-01

    We propose timed automata to model the behavior of real-time systems over time. Our definition provides a simple, and yet powerful, way to annotate state-transition graphs with timing constraints using finitely many real-valued clocks. A timed automaton accepts timed words — strings in which a real-valued time of occurrence is associated with each symbol. We study timed automata from the

  3. Time Varying Feature Data

    NASA Astrophysics Data System (ADS)

    Echterhoff, J.; Simonis, I.; Atkinson, R.

    2012-04-01

    The infrastructure to gather, store and access information about our environment is improving and growing rapidly. The increasing amount of information allows us to get a better understanding of the current state of our environment, historical processes and to simulate and predict the future state of the environment. Finer grained spatial and temporal data and more reliable communications make it easier to model dynamic states and ephemeral features. The exchange of information within and across geospatial domains is facilitated through the use of harmonized information models. The Observations & Measurements (O&M) developed through OGC and standardised by ISO is an example of such a cross-domain information model. It is used in many domains, including meteorology, hydrology as well as the emergency management. O&M enables harmonized representation of common metadata that belong to the act of determining the state of a feature property, whether by sensors, simulations or humans. In addition to the resulting feature property value, information such as the result quality but especially the time that the result applies to the feature property can be represented. Temporal metadata is critical to modelling past and future states of a feature. The features, and the semantics of each property, are defined in domain specific Application Schema using the General Feature Model (GFM) from ISO 19109 and usually encoded following ISO 19136. However, at the moment these standards provide only limited support for the representation and handling of time varying feature data. Features like rivers, wildfires or gas plumes have a defined state - for example geographic extent - at any given point in time. To keep track of changes, a more complex model for example using time-series coverages is required. Furthermore, the representation and management of feature property value changes via the service interfaces defined by OGC and ISO - namely: WFS and WCS - would be rather complex. Keeping track of feature property value corrections or even feature (state change) cancellations for auditing purposes is also not easy to achieve. The aviation domain has strong requirements to represent and manage the state of aeronautical features through time. Being able to efficiently encode and manage feature state changes, keeping track of all changes for auditing purposes and being able to determine the future state of an aeronautical feature as currently known to the system are vital for aeronautical applications. In order to support these requirements, the Aeronautical Information Exchange Model (AIXM) which has been developed by the aviation domain is based on the so called AIXM Temporality Model (AIXM-TM). The AIXM-TM defines various rules for modeling, representing and handling the state of aeronautical features through time. This is a promising approach that can be incorporated into the GFM so that ultimately the modeling and management of time varying feature data is supported in an interoperable and harmonized way in all geospatial domains. This presentation gives an introduction to the main concepts of the AIXM-TM. It also shows how the GFM can be extended to support time varying feature data. Finally, the relationship of O&M and time varying features is discussed.

  4. Are animals stuck in time?

    Microsoft Academic Search

    William A. Roberts

    2002-01-01

    People can time travel cognitively because they can remember events having occurred at particular times in the past (episodic memory) and because they can anticipate new events occurring at particular times in the future. The ability to assign points in time to events arises from human development of a sense of time and its accompanying time-keeping technology. The hypothesis is

  5. Principles of Discrete Time Mechanics

    NASA Astrophysics Data System (ADS)

    Jaroszkiewicz, George

    2014-04-01

    1. Introduction; 2. The physics of discreteness; 3. The road to calculus; 4. Temporal discretization; 5. Discrete time dynamics architecture; 6. Some models; 7. Classical cellular automata; 8. The action sum; 9. Worked examples; 10. Lee's approach to discrete time mechanics; 11. Elliptic billiards; 12. The construction of system functions; 13. The classical discrete time oscillator; 14. Type 2 temporal discretization; 15. Intermission; 16. Discrete time quantum mechanics; 17. The quantized discrete time oscillator; 18. Path integrals; 19. Quantum encoding; 20. Discrete time classical field equations; 21. The discrete time Schrodinger equation; 22. The discrete time Klein-Gordon equation; 23. The discrete time Dirac equation; 24. Discrete time Maxwell's equations; 25. The discrete time Skyrme model; 26. Discrete time quantum field theory; 27. Interacting discrete time scalar fields; 28. Space, time and gravitation; 29. Causality and observation; 30. Concluding remarks; Appendix A. Coherent states; Appendix B. The time-dependent oscillator; Appendix C. Quaternions; Appendix D. Quantum registers; References; Index.

  6. Timing is Everything

    SciTech Connect

    Wiley, H. S.

    2009-08-01

    You want to be ahead of the curve, but not so far ahead that no one can see you. Historically, the scientific community has tended to ignore science that is too innovative or ahead of its time. For this, we are often accused of being biased towards maintaining some fictional status quo. The reason these papers often get forgotten, however, has more to do with the usability of innovative ideas, rather than some perverseness. The classic case is Mendel, whose pioneering ideas on inheritance were ignored for many years. It wasn’t because the scientific community did not know about him; Mendel simply addressed different questions than other scientists at the time. Years later, when chromosomes were identified as a potential mechanism for transmitting genetic information, his ideas suddenly became relevant to a much wider scientific audience.

  7. ANOXIA THROUGH TIME

    Microsoft Academic Search

    Harald Strauss

    The rock record provides unequivocal evidence for multiple times in Earth history during which the entire global ocean or\\u000a parts of it were characterized by severe oxygen-deficiency. Evidence includes geological and paleontological observations\\u000a but also diverse geochemical fingerprints such as trace element abundances, organic geochemical markers or various isotope\\u000a records, all of which are diagnostic for water column anoxia. The

  8. Segmental colonic transit time

    Microsoft Academic Search

    Pierre Arhan; Ghislain Devroede; Bertrand Jehannin; Michel Lanza; Claude Faverdin; Catherine Dornic; Bernard Persoz; Léon Tétreault; Bernard Perey; Denys Pellerin

    1981-01-01

    Mean segmental transit time of radiopaque markers through the right colon, left colon and rectosigmoid areas of adults and\\u000a children has been calculated from their distribution on consecutive plain films of the abdomen. Overall mean transit does\\u000a not differ significantly in the large bowel between adults and children. However, there are regional differences within the\\u000a colon in relation to age.

  9. Tevatron injection timing

    SciTech Connect

    Saritepe, S.; Annala, G.

    1993-06-01

    Bunched beam transfer from one accelerator to another requires coordination and synchronization of many ramped devices. During collider operation timing issues are more complicated since one has to switch from proton injection devices to antiproton injection devices. Proton and antiproton transfers are clearly distinct sequences since protons and antiprotons circulate in opposite directions in the Main Ring (MR) and in the Tevatron. The time bumps are different, the kicker firing delays are different, the kickers and lambertson magnets are different, etc. Antiprotons are too precious to be used for tuning purposes, therefore protons are transferred from the Tevatron back into the Main Ring, tracing the path of antiprotons backwards. This tuning operation is called ``reverse injection.`` Previously, the reverse injection was handled in one supercycle. One batch of uncoalesced bunches was injected into the Tevatron and ejected after 40 seconds. Then the orbit closure was performed in the MR. In the new scheme the lambertson magnets have to be moved and separator polarities have to be switched, activities that cannot be completed in one supercycle. Therefore, the reverse injection sequence was changed. This involved the redefinition of TVBS clock event $D8 as MRBS $D8 thus making it possible to inject 6 proton batches (or coalesced bunches) and eject them one at a time on command, performing orbit closure each time in the MR. Injection devices are clock event driven. The TCLK is used as the reference clock. Certain TCLK events are triggered by the MR beam synchronized clock (MRBS) events. Some delays are measured in terms of MRBS ticks and MR revolutions. See Appendix A for a brief description of the beam synchronized clocks.

  10. Running out of time.

    PubMed

    Zigmond, Jessica

    2013-10-21

    After a glitch-plagued rollout of state and federal healthcare exchanges, officials are scrambling to fix the marketplaces before a crucial mid-November deadline. If the problems can't be fixed in time for consumers to get enrolled by Jan. 1, it will hand ammunition to Republicans who want to delay the ACA's individual mandate. "If you can't enroll people, how can you penalize them?" asks Tom Miller of the American Enterprise Institute. PMID:24340853

  11. The Timing of Sonoluminescence

    E-print Network

    Thomas E. Brennan; Gustave C. Fralick

    2015-02-02

    We measured the timing of sonoluminescence by observing laser light scattered from a single sonoluminescing bubble. We performed this measurement on 23.5 kHz, 17.8 kHz, 13.28 kHz and 7920 Hz systems, and found that the flash typically occurs 100 nanoseconds before the minimum radius. These results motivate a new model of sonoluminescence: the flash results from the discharge of an excited cold condensate formed during the adiabatic expansion of the bubble.

  12. A Journey Through Time

    NSDL National Science Digital Library

    Amy Schneider

    This activity has students create a travel brochure of a geologic period. Links are provided to research questions about the dominant life forms, position of the continents, and climate of the period. Questions in the conclusion section are for students to consider the duration of human existence compared to geologic time, why dinosaurs and humans never fought, and whether they would want to travel to their chosen geologic period.

  13. Telescopes as Time Machines

    NSDL National Science Digital Library

    Astronomical Society of the Pacific

    2008-01-01

    This fun, nighttime hands-on astronomy activity lets learners explore how long it takes for light from different objects in the universe to reach Earth. The activity shows participants the difference among three distance categories: within our Solar System, within the Milky Way, and within the rest of the universe. The PDF contains step-by-step instructions, photos, presentation tips, ready-to-print "Passport through Time" activity handout, and links to background information.

  14. TIME DEPENDENT MAGNETIC INTERACTION

    E-print Network

    Low, Robert

    effects · Analyze the time dependent interactions · How nonlinearity of waves affects the cell stability as the wave shape changes Bz 0 2 4 6 8 10 12 14 16 X0 2 4 Y BZ: -0.0039 -0.0023 -0.0007 0.0009 0.0025 0 predictions? #12;Typical model geometry #12;Flow and waves in Al electrolysis cell · At the interface

  15. Quantum Space-Times

    Microsoft Academic Search

    Abhay Ashtekar

    2010-01-01

    \\u000a In general relativity space-time ends at singularities. The big bang is considered as the Beginning and the big crunch, the\\u000a End. However these conclusions are arrived at by using general relativity in regimes which lie well beyond its physical domain\\u000a of validity. Examples where detailed analysis is possible show that these singularities are naturally resolved by quantum\\u000a geometry effects. Quantum

  16. The Best of Times

    NSDL National Science Digital Library

    Greg Tang

    2013-06-01

    This interactive Flash book of poems by Greg Tang and pictures by Harry Briggs helps children master their times tables through a deeper, more intuitive understanding of multiplication instead of memorization. Students use partial products to multiply larger numbers, first breaking them into smaller, more manageable parts. After reading the poem and examples, learners can test themselves by applying the strategies to a series of 3-5 challenges.

  17. Test of time.

    PubMed

    Bates, Jane

    2015-03-01

    One of the most predictable ways to bring about a cure is to go through the hassle of making a GP appointment; you spend hours on the phone trying to get through to the surgery, plead with a frosty receptionist that three weeks' time is a bit long considering your condition, and no, a telephone consultation is not appropriate because he needs to, er… examine your, er... PMID:25736651

  18. Technology Over Time

    NSDL National Science Digital Library

    In this interactive activity adapted from A Science Odyssey, students will look at how technology in the home has changed over time. Specifically, they will examine a timeline from 1900 to 2010 and think about technological innovations and how they changed our daily lives. The material is intended for students in grades 3-8.The lesson is accompanied by a background essay, standards alignment and discussion questions. Users are encouraged to sign up for a free account.

  19. Einstein in Time

    NSDL National Science Digital Library

    This fun Web site is part of OLogy, where kids can collect virtual trading cards and create projects with them. Here, they are introduced to Einstein's scientific and humanitarian pursuits with two engaging, kid-friendly sections: Einstein in Time, a fascinating look at the major events in his life presented in a timeline and Everyday Einstein: Humanitarian, a quick overview of how he used his fame to draw attention to the things he believed in.

  20. Bath Time with Archimedes

    NSDL National Science Digital Library

    2010-12-14

    This algebra lesson helps students make the connection between functions and their graphs. The model of the level of water in a bathtub is used. Students will watch the graph and a chart of the depth of the water at different time increments. They are then asked to identify the events that caused each change in the graph. A student worksheet is available for download here in a Word Document.

  1. Time Reversal Violation

    SciTech Connect

    Quinn, H; /SLAC

    2009-01-27

    This talk briefly reviews three types of time-asymmetry in physics, which I classify as universal, macroscopic and microscopic. Most of the talk is focused on the latter, namely the violation of T-reversal invariance in particle physics theories. In sum tests of microscopic T-invariance, or observations of its violation, are limited by the fact that, while we can measure many processes, only in very few cases can we construct a matched pair of process and inverse process and observe it with sufficient sensitivity to make a test. In both the cases discussed here we can achieve an observable T violation making use of flavor tagging, and in the second case also using the quantum properties of an antisymmetric coherent state of two B mesons to construct a CP-tag. Both these tagging properties depend only on very general properties of the flavor and/or CP quantum numbers and so provide model independent tests for T-invariance violations. The microscopic laws of physics are very close to T-symmetric. There are small effects that give CP- and T-violating processes in three-generation-probing weak decays. Where a T-violating observable can be constructed we see the relationships between T-violation and CP-violation expected in a CPT conserving theory. These microscopic effects are unrelated to the 'arrow of time' that is defined by increasing entropy, or in the time direction defined by the expansion of our Universe.

  2. Optimal time discrimination.

    PubMed

    Co?kun, Filiz; Sayal?, Zeynep Ceyda; Gürbüz, Emine; Balc?, Fuat

    2015-02-01

    In the temporal bisection task, participants categorize experienced stimulus durations as short or long based on their similarity to previously acquired reference durations. Reward maximization in this task requires integrating endogenous timing uncertainty as well as exogenous probabilities of the reference durations into temporal judgements. We tested human participants on the temporal bisection task with different short and long reference duration probabilities (exogenous probability) in two separate test sessions. Incorrect categorizations were not penalized in Experiment 1 but were penalized in Experiment 2, leading to different levels of stringency in the reward functions that participants tried to maximize. We evaluated the judgements within the framework of optimality. Our participants adapted their choice behaviour in a nearly optimal fashion and earned nearly the maximum possible expected gain they could attain given their level of endogenous timing uncertainty and exogenous probabilities in both experiments. These results point to the optimality of human temporal risk assessment in the temporal bisection task. The long categorization response times (RTs) were overall faster than short categorization RTs, and short but not long categorization RTs were modulated by reference duration probability manipulations. These observations suggested an asymmetry between short and long categorizations in the temporal bisection task. PMID:25026179

  3. Deciding Timed Bisimulation for Timed Automata Using Zone Valuation Graph

    E-print Network

    Prasad, Sanjiva

    Deciding Timed Bisimulation for Timed Automata Using Zone Valuation Graph Shibashis Guha, Chinmay]. In section 2, we give a brief introduction to timed automata, zone and zone valuation graph for a timed was first proved to be decidable for timed automata by Cerans using a product construction method on region

  4. Sensorimotor Function, Gait Patterns and Falls in Community-dwelling Women

    Microsoft Academic Search

    STEPHEN R. LORD; DAVID G. LLOYD; SEK KEUNG LI

    1996-01-01

    Summary Tests of vision, vestibular function, peripheral sensation, strength, reaction time, balance and gait were administered to 183 community-dwelling women aged 22-99 years. Walking speed, stride length and cadence declined with age with corresponding increases in stance duration and percentage of the stride in the stance phase. Visual acuity and contrast sensitivity, tactile and vibration sense in the lower limb,

  5. The family system grief process as a communicated process: Understanding grief through Virginia Satir's growth model

    Microsoft Academic Search

    Glenn Vincent Breen

    1996-01-01

    This thesis argues that the family system grief process can be understood as a communicated process. Through using Virginia Satir's communication stance theory, and applying it to a case study, this thesis found that when a family member dies, the family system enters a period of chaos. During the chaos time family members may rely on incongruent communication stances to

  6. Space-time qubits

    E-print Network

    J. L. Pienaar; C. R. Myers; T. C. Ralph

    2011-04-18

    We construct a qubit algebra from field creation and annihilation operators acting on a global vacuum state. Particles to be used as qubits are created from the vacuum by a near-deterministic single particle source. Our formulation makes the space-time dependence of the qubits explicit, preparing the way for quantum computation within a field framework. The method can be generalized to deal with interacting qubits whose wavepackets are not perfectly matched to each other. We give an example of how to calculate the Heisenberg evolution of a simple two-qubit circuit, taking expectation values in the field vacuum state.

  7. The Timing of Sonoluminescence

    NASA Astrophysics Data System (ADS)

    Brennan, Thomas; Fralick, Gustave

    2012-02-01

    We measured the timing of the sonoluminescence flash by scattering laser light from the bubble. We performed this measurement on 17.8 kHz, 13.28 kHz and 7920 Hz systems and found that the flash typically occurs 100 nanoseconds before the minimum radius, contrary to previous claims that the flash always occurs within a nanosecond of the minimum radius. These results are important because they imply that previous hot models of sonoluminescence are wrong. We propose a new model: that the flash results from the discharge of an excited cold condensate, formed during the adiabatic expansion of the bubble.

  8. The Timing of Sonoluminescence

    E-print Network

    Brennan, Thomas E

    2011-01-01

    We measured the timing of sonoluminescence by observing laser light scattered from a sonoluminescing bubble. We performed this measurement on 17.8 kHz, 13.28 kHz and 7920 Hz systems and found that the flash typically occurs 100 nanoseconds before the minimum radius, contrary to previous claims that the flash always occurs within a nanosecond of the minimum radius. These results imply that hot models of sonoluminescence, which require the flash to occur within a nanosecond of the minimum radius, are wrong. We propose a new model: that the flash results from the discharge of an excited cold condensate, formed during the adiabatic expansion of the bubble.

  9. Space-time qubits

    SciTech Connect

    Pienaar, J. L.; Myers, C. R.; Ralph, T. C. [Centre for Quantum Computation and Communication Technology, School of Mathematics and Physics, University of Queensland, Brisbane 4072, Queensland (Australia)

    2011-08-15

    We construct a qubit algebra from field creation and annihilation operators acting on a global vacuum state. Particles to be used as qubits are created from the vacuum by a near-deterministic single-particle source. Our formulation makes the space-time dependence of the qubits explicit, preparing the way for quantum computation within a field framework. The method can be generalized to deal with interacting qubits whose wave packets are not perfectly matched to each other. We give an example of how to calculate the Heisenberg evolution of a simple two-qubit circuit, taking expectation values in the field vacuum state.

  10. Space time and rotations

    E-print Network

    A. Tartaglia

    2002-01-04

    The paper considers the problem of finding the metric of space time around a rotating, weakly gravitating body. Both external and internal metric tensors are consistently found, together with an appropriate source tensor. All tensors are calculated at the lowest meaningful approximation in a power series. The two physical parameters entering the equations (the mass and the angular momentum per unit mass) are assumed to be such that the mass effects are negligible with respect to the rotation effects. A non zero Riemann tensor is obtained. The order of magnitude of the effects at the laboratory scale is such as to allow for experimental verification of the theory.

  11. Real time Faraday spectrometer

    DOEpatents

    Smith, Jr., Tommy E. (Fremont, CA); Struve, Kenneth W. (Albuquerque, NM); Colella, Nicholas J. (Livermore, CA)

    1991-01-01

    This invention uses a dipole magnet to bend the path of a charged particle beam. As the deflected particles exit the magnet, they are spatially dispersed in the bend-plane of the magnet according to their respective momenta and pass to a plurality of chambers having Faraday probes positioned therein. Both the current and energy distribution of the particles is then determined by the non-intersecting Faraday probes located along the chambers. The Faraday probes are magnetically isolated from each other by thin metal walls of the chambers, effectively providing real time current-versus-energy particle measurements.

  12. Time and Cycles: Dendrochronology

    NSDL National Science Digital Library

    In this activity, students will use pre-marked paper strips to simulate tree-ring core samples to help them understand that data for past climate changes can be gathered from sources beyond long-term weather observations. Students will be able to recognize the direct impact of climate on annual tree growth patterns. The student guide has an overall description of the activity, a list of materials, the procedure, and observations and questions. The instructor guide contains detailed background material, learning goals, alignment to national standards, grade level/time, details on materials and preparation, procedure, assessment ideas, and modifications for alternative learners.

  13. Exploring Time Series Plots

    NSDL National Science Digital Library

    2012-08-03

    Students will explore time series plots and raw data to understand the role of sea surface temperature increases on arctic ice melt. This is part three of a four-part activity on polar science. The activity builds on the knowledge gained in Using Data and Images to Understand Albedo (part 2). Extension activities examining air and sea surface temperature in relation to changing Earth albedo are included. Information is provided on data access using the NOAA Earth System Research Laboratory Web site. This activity is one of several learning activities connected with the 2007 GLOBE Earth system poster.

  14. THEMIS and Substorm Timing

    NASA Technical Reports Server (NTRS)

    Sibeck, D. G.

    2010-01-01

    The THEMIS mission represents the culmination of many years of planning directed towards understanding the processes that drive and trigger geomagnetic substorms. Following Akasofu's discovery of the substorm cycle, it became increasingly clear that timing questions provide the key to discriminating between proposed 'inside-out' and 'outside-in' models for substorms, triggered respectively by current disruption and magnetic reconnection. THEMIS observations provide a wealth of information that is currently being investigated to resolve this question. While observations in the magnetotail generally point towards reconnection. those on the ground point towards current disruption. This talk reviews the relevant observations and recent efforts at reconciliation.

  15. Biotechnology Through Time

    NSDL National Science Digital Library

    2014-04-30

    In this activity, learners investigate the history and development of agricultural biotechnology. This experience begins with a Bio-Fest, in which learners use their senses to make observations about root beer, assorted cheeses, bread and yogurt. Learners are encouraged to think about the process of making food and how it has changed over time. This leads to a discussion about biotechnology. Learners complete the lesson by researching and completing a timeline. This activity is featured on pp.7-8 (part of a lesson that begins on p.6) of the "Yesterday, Today and Tomorrow: Agricultural Biology" unit of study for grades 6-8.

  16. Native American Times

    NSDL National Science Digital Library

    The Native American Times makes good on its promise to deliver "today's independent Indian news." The site has a clean design that includes ten sections covering topics like business, culture, education, sports, and powwows. The News area offers a nice digest of what's going on in several areas of interest to Native Americans, with topical headlines that include "Cherokee Art Market Announces Winners" and "Yakama Maintain Wild Horse Race Tradition." The site also includes a great jobs area for folks who might be looking for Native American-focused work in public policy, community development, technology, and other fields.

  17. A Matter of Time

    NASA Technical Reports Server (NTRS)

    2006-01-01

    16 February 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a portion of the south polar residual cap where the effects of sublimation are apparent. Over extended periods of time, sublimation 'eats' away at the smoother appearing material (largely composed of frozen carbon dioxide), darkening the scarps and creating the irregularly shaped depressions that are present throughout much of the scene.

    Location near: 87.1oS, 69.3oW Image width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Summer

  18. Climate Time Machine

    NSDL National Science Digital Library

    Go backward and forward in time with this interactive visualization that illustrates how the Earth's climate has changed in recent history. Topics covered are Sea Ice: ice cap extent 1979 - 2007, Sea Level: effect on coastal regions for each meter of sea level rise, Carbon Emissions: amount of annual fossil fuel emissions produced by the top 12 nations or regions from 1980-2004, and Average Global Temperature: a color-coded map showing the progression of changing global surface temperatures from 1885 to 2007.

  19. AlternaTime

    NSDL National Science Digital Library

    Emery, George.

    1969-12-31

    Timelines are often a fun and easy way to learn a great deal about a subject. George Emery, a librarian at Canisius College, has been collecting timelines on the Internet since 1993 and kindly presents them on the AlternaTime Web site. The science and technology timeline links have titles which include science timeline, chronology of scientific developments, physics, evolutionary and geological timeline, atomic, Mendel, space program, NASA, alchemical, strange science, and dozens more. A simple but useful metasite, visitors can also find links to timelines about history and culture, arts and literature, popular culture, and science fiction.

  20. “Signs of the Times

    PubMed Central

    Chakrabarti, Pratik

    2009-01-01

    Medical practice and research in colonial India historically had been an imperial preserve, dominated by the elite members of the Indian Medical Service. This was contested from the 1900s on by the emerging Indian nationalism. This essay studies debates about the establishment of a medical research institution and how actors imposed the political identities of nationalism on British colonial practices of medical science. At the same time, Indian nationalism was also drawing from other emerging ideas around health and social welfare. The Indian nationalists and doctors sought to build the identities of the new nation and its medicine around their own ideas of its geography, people, and welfare. PMID:20027771