Sample records for unipedal stance time

  1. Unipedal stance testing as an indicator of fall risk among older outpatients

    Microsoft Academic Search

    Edward A. Hurvitz; James K. Richardson; Robert A. Werner; Anne M. Ruhl; Matthew R. Dixon

    2000-01-01

    Objective: To test the hypothesis that a decreased unipedal stance time (UST) is associated with a history of falling among older persons.Design: Fifty-three subjects underwent a standardized history and physical examination and three trials of timed unipedal stance.Setting: The electroneuromyography laboratories of tertiary care Veterans Administration and university hospitals.Subjects: Ambulatory outpatients 50 years and older referred for electrodiagnostic studies.Outcome measures:

  2. 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

  3. The Correlation between Dynamic Balance Measures and Stance Sub-phase COP Displacement Time in Older Adults during Obstacle Crossing

    PubMed Central

    Park, Seol; Ko, Yu-Min; Park, Ji-Won

    2013-01-01

    [Purpose] This study examined the relationship between the center of pressure (COP) displacement time during the stance subphases and dynamic balance ability when elderly cross obstacles 0, 10, and 40?cm in height. [Subjects] Fifteen older adults were enrolled in this study (?65?years of age). [Methods] An F-Scan System was used to measure the COP displacement time when subjects crossed obstacles 0, 10, and 40?cm in height, and the Dynamic Gait Index, Berg Balance Scale, and Four Square Step Test were used to measure dynamic balance ability. [Results] The Dynamic Gait Index, Berg Balance Scale, and Four Square Step Test were correlated with each other. Dynamic balance tests were correlated with the COP displacement time during the stance phase. At obstacle heights of 10 and 40?cm during loading response and at all heights during pre-swing, there were correlations with dynamic balance ability. However, dynamic balance ability did not affect the COP displacement time during mid-stance and terminal stance. [Conclusion] People with a lower dynamic balance ability show a larger COP displacement time during loading response and pre-swing. Therefore, dynamic balance ability can be predicted by measuring the COP displacement time. PMID:24259944

  4. Postural Performance and Strategy in the Unipedal Stance of Soccer Players at Different Levels of Competition

    PubMed Central

    Paillard, Thierry; Noé, Frédéric; Rivière, Terence; Marion, Vincent; Montoya, Richard; Dupui, Philippe

    2006-01-01

    Context: Sport training enhances the ability to use somatosensory and otolithic information, which improves postural capabilities. Postural changes are different according to the sport practiced, but few authors have analyzed subjects' postural performances to discriminate the expertise level among highly skilled athletes within a specific discipline. Objective: To compare the postural performance and the postural strategy between soccer players at different levels of competition (national and regional). Design: Repeated measures with 1 between-groups factor (level of competition: national or regional) and 1 within-groups factor (vision: eyes open or eyes closed). Dependent variables were center-of-pressure surface area and velocity; total spectral energy; and percentage of low-, medium-, and high-frequency band. Setting: Sports performance laboratory. Patients or Other Participants: Fifteen national male soccer players (age = 24 ± 3 years, height = 179 ± 5 cm, mass = 72 ± 3 kg) and 15 regional male soccer players (age = 23 ± 3 years, height = 174 ± 4 cm, mass = 68 ± 5 kg) participated in the study. Intervention(s): The subjects performed posturographic tests with eyes open and closed. Main Outcome Measure(s): While subjects performed static and dynamic posturographic tests, we measured the center of foot pressure on a force platform. Spatiotemporal center-of-pressure measurements were used to evaluate the postural performance, and a frequency analysis of the center-of-pressure excursions (fast Fourier transform) was conducted to estimate the postural strategy. Results: Within a laboratory task, national soccer players produced better postural performances than regional players and had a different postural strategy. The national players were more stable than the regional players and used proprioception and vision information differently. Conclusions: In the test conditions specific to playing soccer, level of playing experience influenced postural control performance measures and strategies. PMID:16791302

  5. Asymmetric balance control between legs for quiet but not for perturbed stance.

    PubMed

    Vieira, Osvaldo; Coelho, Daniel Boari; Teixeira, Luis Augusto

    2014-10-01

    Interlateral performance asymmetry in upright balance control was evaluated in this investigation by comparing unipedal stance on the right versus the left leg. Participants were healthy young adults, hand-foot congruent preference for the right body side. Balance performance was evaluated in unperturbed quiet stance and in the recovery of balance stability following a mechanical perturbation induced by unexpected load release. Evaluation was made under availability of full sensory information, and under deprivation of vision combined with distortion of sensory inputs from the feet soles. Results from perturbed posture revealed that muscular response latency and postural sway were symmetric between the legs. Unipedal stance was more stable when the body was supported on the right as compared with the left leg. No interaction was found between leg and sensory condition. Our findings are interpreted as resulting from specialization of the sensorimotor system controlling the right leg for continuous low-magnitude postural adjustments, while corrections to large-scale stance sway are symmetrically controlled between body sides. PMID:24954557

  6. Feedforward ankle strategy of balance during quiet stance in adults

    PubMed Central

    Gatev, Plamen; Thomas, Sherry; Kepple, Thomas; Hallett, Mark

    1999-01-01

    We studied quiet stance investigating strategies for maintaining balance. Normal subjects stood with natural stance and with feet together, with eyes open or closed. Kinematic, kinetic and EMG data were evaluated and cross-correlated.Cross-correlation analysis revealed a high, positive, zero-phased correlation between anteroposterior motions of the centre of gravity (COG) and centre of pressure (COP), head and COG, and between linear motions of the shoulder and knee in both sagittal and frontal planes. There was a moderate, negative, zero-phased correlation between the anteroposterior motion of COP and ankle angular motion.Narrow stance width increased ankle angular motion, hip angular motion, mediolateral sway of the COG, and the correlation between linear motions of the shoulder and knee in the frontal plane. Correlations between COG and COP and linear motions of the shoulder and knee in the sagittal plane were decreased. The correlation between the hip angular sway in the sagittal and frontal planes was dependent on interaction between support and vision.Low, significant positive correlations with time lags of the maximum of cross-correlation of 250-300 ms were found between the EMG activity of the lateral gastrocnemius muscle and anteroposterior motions of the COG and COP during normal stance. Narrow stance width decreased both correlations whereas absence of vision increased the correlation with COP.Ankle mechanisms dominate during normal stance especially in the sagittal plane. Narrow stance width decreased the role of the ankle and increased the role of hip mechanisms in the sagittal plane, while in the frontal plane both increased.The modulation pattern of the lateral gastrocnemius muscle suggests a central program of control of the ankle joint stiffness working to predict the loading pattern. PMID:9882761

  7. 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.''

  8. Stance and Intertextuality in Written Discourse.

    ERIC Educational Resources Information Center

    Beach, Richard; Anson, Chris M.

    1992-01-01

    Studies intertextuality in teachers' peer dialog journal exchanges. Findings show that the meaning of intertextual links between entries has much to do with partners' shared stances toward gender roles (for the exchange between two women) and their roles as teachers within the school (for the exchange between two men). (Author)

  9. Ratite Footprints and the Stance and Gait

    E-print Network

    Olsen, Paul E.

    footprints of the Mesozoic Era attributed to theropod dinosaurs. Of par- ticular interest,'(i) the rheaRatite Footprints and the Stance and Gait of Mesozoic Theropods KEVIN PADIAN AND PAUL E. OLSEN, and the toes and claws leave no drag marks. These are all characteristic of Mesozoic theropod (and ornithopod

  10. Multicontact stances planning for multiple agents

    Microsoft Academic Search

    Karim Bouyarmane; Abderrahmane Kheddar

    2011-01-01

    We propose a generalized framework together with an algorithm to plan a discrete sequence of multi-contact stances that brings a set of collaborating robots and manipu- lated objects from a specified initial configuration to a desired goal through non-gaited acyclic contacts with their environment or among each other. The broad range of applications of this generic algorithm includes legged locomotion

  11. Effects of stance angle on postural stability and performance with national-standard air pistol competitors.

    PubMed

    Hawkins, Richard Nelson

    2013-01-01

    The effects of stance angle on postural stability and shooting processes were studied using eight national-standard male air-pistol shooters. Each shooter performed 60 shots each in four stance angles (0°, 15°, 30° and 45° from the line of fire). Postural stability was determined by measuring change in centre of pressure with a dual-force platform system assessing centre-of-pressure (COP) excursion (average difference of the centre of pressure from the mean) and COP speed (total COP path divided by time). Shooting process measures were determined by using a NOPTEL ST-2000 optoelectronic system. Score was assessed with a Sius Ascor S10 electronic scoring system. The results revealed no significant difference among the various stance angles; COP excursion or COP speed, p>0.05. Results indicated a significant stance angle effect with the shooting process measure, hit fine (percentage of hold within an area the size of the 10-ring when centred over the actual shot; p = 0.025) and the shooting performance measure adjusted score (raw score adjusted for true zero; p=0.008). Moreover, best overall performance was with a stance angle of 15°. These findings suggest that stance angle may affect pistol stability and performance in air-pistol athletes. PMID:24050465

  12. Reviewer Stances and Writer Perceptions in EFL Peer Review Training

    ERIC Educational Resources Information Center

    Min, Hui-Tzu

    2008-01-01

    Research has shown that reviewers' stances can impact the efficacy of peer response/review and subsequent revision. The purpose of this classroom-based study was to compare reviewer stances and writer perceptions of/and attitudes toward these stances prior to and after peer review training in an EFL writing class. Eighteen intermediate EFL writers…

  13. Methods for exploring expressive stance

    Microsoft Academic Search

    Michael Neff; Eugene Fiume

    2004-01-01

    The postures a character adopts over time are a key expressive aspect of her movement. While IK tools help a character achieve positioning constraints, there are few tools that help an animator with the expressive aspects of a character's poses. Three aspects are combined in good pose design: achieving a set of world space constraints, finding a body shape that

  14. [Recognition of walking stance phase and swing phase based on moving window].

    PubMed

    Geng, Xiaobo; Yang, Peng; Wang, Xinran; Geng, Yanli; Han, Yu

    2014-04-01

    Wearing transfemoral prosthesis is the only way to complete daily physical activity for amputees. Motion pattern recognition is important for the control of prosthesis, especially in the recognizing swing phase and stance phase. In this paper, it is reported that surface electromyography (sEMG) signal is used in swing and stance phase recognition. sEMG signal of related muscles was sampled by Infiniti of a Canadian company. The sEMG signal was then filtered by weighted filtering window and analyzed by height permitted window. The starting time of stance phase and swing phase is determined through analyzing special muscles. The sEMG signal of rectus femoris was used in stance phase recognition and sEMG signal of tibialis anterior is used in swing phase recognition. In a certain tolerating range, the double windows theory, including weighted filtering window and height permitted window, can reach a high accuracy rate. Through experiments, the real walking consciousness of the people was reflected by sEMG signal of related muscles. Using related muscles to recognize swing and stance phase is reachable. The theory used in this paper is useful for analyzing sEMG signal and actual prosthesis control. PMID:25039126

  15. Stance controlled knee flexion improves stimulation driven walking after spinal cord injury

    PubMed Central

    2013-01-01

    Background Functional neuromuscular stimulation (FNS) restores walking function after paralysis from spinal cord injury via electrical activation of muscles in a coordinated fashion. Combining FNS with a controllable orthosis to create a hybrid neuroprosthesis (HNP) has the potential to extend walking distance and time by mechanically locking the knee joint during stance to allow knee extensor muscle to rest with stimulation turned off. Recent efforts have focused on creating advanced HNPs which couple joint motion (e.g., hip and knee or knee and ankle) to improve joint coordination during swing phase while maintaining a stiff-leg during stance phase. Methods The goal of this study was to investigate the effects of incorporating stance controlled knee flexion during loading response and pre-swing phases on restored gait. Knee control in the HNP was achieved by a specially designed variable impedance knee mechanism (VIKM). One subject with a T7 level spinal cord injury was enrolled and served as his own control in examining two techniques to restore level over-ground walking: FNS-only (which retained a stiff knee during stance) and VIKM-HNP (which allowed controlled knee motion during stance). The stimulation pattern driving the walking motion remained the same for both techniques; the only difference was that knee extensor stimulation was constant during stance with FNS-only and modulated together with the VIKM to control knee motion during stance with VIKM-HNP. Results Stance phase knee angle was more natural during VIKM-HNP gait while knee hyperextension persisted during stiff-legged FNS-only walking. During loading response phase, vertical ground reaction force was less impulsive and instantaneous gait speed was increased with VIKM-HNP, suggesting that knee flexion assisted in weight transfer to the leading limb. Enhanced knee flexion during pre-swing phase also aided flexion during swing, especially when response to stimulation was compromised. Conclusions These results show the potential advantages of incorporating stance controlled knee flexion into a hybrid neuroprosthesis for walking. The addition of such control to FNS driven walking could also enable non-level walking tasks such as uneven terrain, slope navigation and stair descent where controlled knee flexion during weight bearing is critical. PMID:23826711

  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. Educating the design stance: issues of coherence and transgression.

    PubMed

    Freeman, Norman H; Allen, Melissa L

    2013-04-01

    Bullot & Reber (B&R) put forth a design stance to fuse psychological and art historical accounts of visual thinking into a single theory. We argue that this aspect of their proposal needs further fine-tuning. Issues of transgression and coherence are necessary to provide stability to the design stance. We advocate looking to Art Education for such fundamentals of picture understanding. PMID:23507096

  18. Postural fluctuations during pointing from a unilateral or bilateral stance

    Microsoft Academic Search

    Ing-Shiou Hwang; Chien-Ting Huang; Rong-Ju Cherng; Chien-Chun Huang

    2006-01-01

    An experiment was conducted to compare the effects of bilateral and unilateral stance on postural fluctuations and intralimb coordination during active balance control. Fifteen participants stood bilaterally and unilaterally while conducting a pointing task with an outstretched arm. Excursion of center of foot pressure (CoP) and limb movements were recorded with a force plate and eight dual-axis accelerometers, respectively. Compared

  19. Angular-velocity control approach for stance-control orthoses.

    PubMed

    Lemaire, Edward D; Goudreau, Louis; Yakimovich, Terris; Kofman, Jonathan

    2009-10-01

    Currently, stance-control knee orthoses require external control mechanisms to control knee flexion during stance and allow free knee motion during the swing phase of gait. A new angular-velocity control approach that uses a rotary-hydraulic device to resist knee flexion when the knee angular velocity passes a preset threshold is presented. This angular-velocity approach for orthotic stance control is based on the premise that knee-flexion angular velocity during a knee-collapse event, such as a stumble or fall, is greater than that during walking. The new hydraulic knee-flexion control device does not require an external control mechanism to switch from free motion to stance control mode. Functional test results demonstrated that the hydraulic angular-velocity activated knee joint provided free knee motion during walking, engaged upon knee collapse, and supported body weight while the end-user recovered to a safe body position. The joint was tested to 51.6 Nm in single loading tests and passed 200,000 repeated loading cycles with a peak load of 88 Nm per cycle. The hydraulic, angular velocity activation approach has potential to improve safety and security for people with lower extremity weakness or when recovering from joint trauma. PMID:19497821

  20. Stability of Statically Balanced Stances for Legged Robots with Compliance

    Microsoft Academic Search

    Christian Ridderström

    2002-01-01

    This paper presents a new criterion for the asymptotic stance stability of a statically balanced legged robot. Typ- ically, the static balance criterion only considers that the centre of mass is projected within the support area. This work shows that when the combined system is not stiff enough (as specified in the criterion), a so called \\

  1. 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

  2. Situating Reader Stance within and beyond the Efferent-Aesthetic Continuum

    ERIC Educational Resources Information Center

    Paulson, Eric J.; Armstrong, Sonya L.

    2010-01-01

    The purpose of this theoretical essay is to encourage critical reflection of the relationship of specific reading events to traditional conceptualizations of reader stance. While conventional models of reader stance are useful for considering many aspects of reading, there are reading events that engender stances that appear to lie outside of the…

  3. Observational stance as a predictor of subjective and genital sexual arousal in men and women.

    PubMed

    Bossio, Jennifer A; Spape, Jessica; Lykins, Amy D; Chivers, Meredith L

    2014-01-01

    Observational stance refers to the perspective a person takes while viewing a sexual stimulus, either as a passive observer (observer stance) or an active participant (participant stance). The objective of the current study was to examine the relationship between observational stance and sexual arousal (subjective and genital) across a range of sexual stimuli that do or do not correspond with a participant's sexual attraction (preferred or nonpreferred stimuli, respectively). Regression analyses revealed that, for men (n = 44), participant stance significantly predicted subjective and genital arousal. Women's (n = 47) observer and participant stance predicted subjective arousal but not genital arousal. Analysis of variance showed that participant stance was greatest under preferred sexual stimuli conditions for all groups of participants, while observer stance scores revealed a less consistent pattern of response. This was particularly true for opposite-sex-attracted women, whose ratings of observer stance were lowest for preferred stimuli. Observational stance does not appear to account for gender differences in specificity of sexual arousal; for men, however, participant stance uniquely predicted genital response after controlling for sexual attractions. Similarities in the relationships between men's and women's observational stance and sexual responses challenge previous claims of gender differences in how men and women view erotica. PMID:23514448

  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. Potential roles of force cues in human stance control

    Microsoft Academic Search

    Christian Cnyrim; Thomas Mergner; Christoph Maurer

    2009-01-01

    Human stance is inherently unstable. A small deviation from upright body orientation is enough to yield a gravitational component\\u000a in the ankle joint torque, which tends to accelerate the body further away from upright (‘gravitational torque’; magnitude\\u000a is related to body-space lean angle). Therefore, to maintain a given body lean position, a corresponding compensatory torque\\u000a must be generated. It is

  6. Coherence analysis of muscle activity during quiet stance

    Microsoft Academic Search

    Mark Saffer; Tim Kiemel; John Jeka

    2008-01-01

    Studies of muscle activation during perturbed standing have demonstrated that the typical patterns of coordination (“ankle\\u000a strategy” and “hip strategy”) are controlled through multiple muscles activated in a distal-to-proximal or proximal-to-distal\\u000a temporal pattern. In contrast, quiet stance is thought to be maintained primarily through the ankle musculature. Recently,\\u000a spectral analysis of inter-segment body motion revealed the coexistence of both ankle

  7. 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

  8. 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

  9. The influence of ankle muscle activation on postural sway during quiet stance.

    PubMed

    Warnica, Meagan J; Weaver, Tyler B; Prentice, Stephen D; Laing, Andrew C

    2014-04-01

    Although balance during quiet standing is postulated to be influenced by multiple factors, including ankle stiffness, it is unclear how different mechanisms underlying increases in stiffness affect balance control. Accordingly, this study examined the influence of muscle activation and passive ankle stiffness increases on the magnitude and frequency of postural sway. Sixteen young adults participated in six quiet stance conditions including: relaxed standing, four muscle active conditions (10%, 20%, 30% and 40% maximum voluntary contraction (MVC)), and one passive condition wearing an ankle foot orthotic (AFO). Kinetics were collected from a force plate, while whole-body kinematics were collected with a 12-sensor motion capture system. Bilateral electromyographic signals were recorded from the tibialis anterior and medial gastrocnemius muscles. Quiet stance sway amplitude (range and root mean square) and frequency (mean frequency and velocity) in the sagittal plane were calculated from time-varying centre of gravity (COG) and centre of pressure (COP) data. Compared to the relaxed standing condition, metrics of sway amplitude were significantly increased (between 37.5 and 63.2%) at muscle activation levels of 30% and 40% MVC. Similarly, frequency measures increased between 30.5 and 154.2% in the 20-40% MVC conditions. In contrast, passive ankle stiffness, induced through the AFO, significantly decreased sway amplitude (by 23-26%), decreased COG velocity by 13.8%, and increased mean COP frequency by 24.9%. These results demonstrate that active co-contraction of ankle musculature (common in Parkinson's Disease patients) may have differential effects on quiet stance balance control compared to the use of an ankle foot orthotic (common for those recovering from stroke). PMID:24613374

  10. How Joint Torques Affect Hamstring Injury Risk in Sprinting Swing–Stance Transition

    PubMed Central

    SUN, YULIANG; WEI, SHUTAO; ZHONG, YUNJIAN; FU, WEIJIE; LI, LI; LIU, YU

    2015-01-01

    ABSTRACT Purpose The potential mechanisms of hamstring strain injuries in athletes are not well understood. The study, therefore, was aimed at understanding hamstring mechanics by studying loading conditions during maximum-effort overground sprinting. Methods Three-dimensional kinematics and ground reaction force data were collected from eight elite male sprinters sprinting at their maximum effort. Maximal isometric torques of the hip and knee were also collected. Data from the sprinting gait cycle were analyzed via an intersegmental dynamics approach, and the different joint torque components were calculated. Results During the initial stance phase, the ground reaction force passed anteriorly to the knee and hip, producing an extension torque at the knee and a flexion torque at the hip joint. Thus, the active muscle torque functioned to produce flexion torque at the knee and extension torque at the hip. The maximal muscle torque at the knee joint was 1.4 times the maximal isometric knee flexion torque. During the late swing phase, the muscle torque counterbalanced the motion-dependent torque and acted to flex the knee joint and extend the hip joint. The loading conditions on the hamstring muscles were similar to those of the initial stance phase. Conclusions During both the initial stance and late swing phases, the large passive torques at both the knee and hip joints acted to lengthen the hamstring muscles. The active muscle torques generated mainly by the hamstrings functioned to counteract those passive effects. As a result, during sprinting or high-speed locomotion, the hamstring muscles may be more susceptible to high risk of strain injury during these two phases. PMID:24911288

  11. Stability and the maintenance of balance following a perturbation from quiet stance.

    PubMed

    Stirling, J R; Zakynthinaki, M S

    2004-03-01

    We investigate stability and the maintenance of balance with the use of tools from dynamical systems. In particular we investigate the application of such tools to the study of the ground reaction forces resulting from an athlete being perturbed from quiet stance. We develop a nonlinear model consisting of a set of coupled vector fields for the derivative with respect to time of the angles between the resultant ground reaction forces and the vertical in the anteroposterior and mediolateral directions. This model contains a basin of attraction bound by a closed curve which we call the critical curve. It is only inside this curve that perturbations can be corrected, with the orbit spiraling onto an attractor corresponding to quiet stance. We show how the critical curve and also the strength of the attractor found in the basin of attraction can be fit to model the experimental data (time series) for an individual athlete. We also discuss how our model can be used to identify nonsymmetric behavior caused by muscle imbalances and differences in the ranges of motion on either side of the body. PMID:15003048

  12. Stance-phase force on the opposite limb dictates swing-phase afferent presynaptic inhibition during locomotion

    PubMed Central

    Hayes, Heather Brant; Chang, Young-Hui

    2012-01-01

    Presynaptic inhibition is a powerful mechanism for selectively and dynamically gating sensory inputs entering the spinal cord. We investigated how hindlimb mechanics influence presynaptic inhibition during locomotion using pioneering approaches in an in vitro spinal cord–hindlimb preparation. We recorded lumbar dorsal root potentials to measure primary afferent depolarization-mediated presynaptic inhibition and compared their dependence on hindlimb endpoint forces, motor output, and joint kinematics. We found that stance-phase force on the opposite limb, particularly at toe contact, strongly influenced the magnitude and timing of afferent presynaptic inhibition in the swinging limb. Presynaptic inhibition increased in proportion to opposite limb force, as well as locomotor frequency. This form of presynaptic inhibition binds the sensorimotor states of the two limbs, adjusting sensory inflow to the swing limb based on forces generated by the stance limb. Functionally, it may serve to adjust swing-phase sensory transmission based on locomotor task, speed, and step-to-step environmental perturbations. PMID:22442562

  13. Influence of Stance Width on Frontal Plane Postural Dynamics and Coordination in Human Balance Control

    PubMed Central

    Goodworth, Adam D.

    2010-01-01

    The influence of stance width on frontal plane postural dynamics and coordination in human bipedal stance was studied. We tested the hypothesis that when subjects adopt a narrow stance width, they will rely heavily on nonlinear control strategies and coordinated counter-phase upper and lower body motion to limit center-of-mass (CoM) deviations from upright; as stance increases, the use of these strategies will diminish. Freestanding frontal plane body sway was evoked through continuous pseudorandom rotations of the support surface on which subjects stood with various stimulus amplitudes. Subjects were either eyes open (EO) or closed (EC) and adopted various stance widths. Upper body, lower body, and CoM kinematics were summarized using root-mean-square and peak-to-peak measures, and dynamic behavior was characterized using frequency-response and impulse-response functions. In narrow stance, CoM frequency-response function gains were reduced with increasing stimulus amplitude and in EO compared with EC; in wide stance, gain reductions were much less pronounced. Results show that the narrow stance postural system is nonlinear across stimulus amplitude in both EO and EC conditions, whereas the wide stance postural system is more linear. The nonlinearity in narrow stance is likely caused by an amplitude-dependent sensory reweighting mechanism. Finally, lower body and upper body sway were approximately in-phase at low frequencies (<1 Hz) and out-of-phase at high frequencies (>1 Hz) across all stance widths, and results were therefore inconsistent with the hypothesis that subjects made greater use of coordinated counter-phase upper and lower body motion in narrow compared with wide stance conditions. PMID:20427616

  14. Potential roles of force cues in human stance control.

    PubMed

    Cnyrim, Christian; Mergner, Thomas; Maurer, Christoph

    2009-04-01

    Human stance is inherently unstable. A small deviation from upright body orientation is enough to yield a gravitational component in the ankle joint torque, which tends to accelerate the body further away from upright ('gravitational torque'; magnitude is related to body-space lean angle). Therefore, to maintain a given body lean position, a corresponding compensatory torque must be generated. It is well known that subjects use kinematic sensory information on body-space lean from the vestibular system for this purpose. Less is known about kinetic cues from force/torque receptors. Previous work indicated that they are involved in compensating external contact forces such as a pull or push having impact on the body. In this study, we hypothesized that they play, in addition, a role when the vestibular estimate of the gravitational torque becomes erroneous. Reasons may be sudden changes in body mass, for instance by a load, or an impairment of the vestibular system. To test this hypothesis, we mimicked load effects on the gravitational torque in normal subjects and in patients with chronic bilateral vestibular loss (VL) with eyes closed. We added/subtracted extra torque to the gravitational torque by applying an external contact force (via cable winches and a body harness). The extra torque was referenced to body-space lean, using different proportionality factors. We investigated how it affected body-space lean responses that we evoked using sinusoidal tilts of the support surface (motion platform) with different amplitudes and frequencies (normals +/-1 degrees, +/-2 degrees, and +/-4 degrees at 0.05, 0.1, 0.2, and 0.4 Hz; patients +/-1 degrees and +/-2 degrees at 0.05 and 0.1 Hz). We found that added/subtracted extra torque scales the lean response in a systematic way, leading to increase/decrease in lean excursion. Expressing the responses in terms of gain and phase curves, we compared the experimental findings to predictions obtained from a recently published sensory feedback model. For the trials in which the extra torque tended to endanger stance control, predictions in normals were better when the model included force cues than without these cues. This supports our notion that force cues provide an automatic 'gravitational load compensation' upon changes in body mass in normals. The findings in the patients support our notion that the presumed force cue mechanism provides furthermore vestibular loss compensation. Patients showed a body-space stabilization that cannot be explained by ankle angle proprioception, but must involve graviception, most likely by force cues. Our findings suggest that force cues contribute considerably to the redundancy and robustness of the human stance control system. PMID:19219426

  15. Beyond backchannels: co-construction of dyadic stance by reciprocal reinforcement of smiles between virtual agents.

    E-print Network

    Pelachaud, Catherine

    , several virtual agents are able to react to their partners' behaviour through their non-verbal behaviour a dyadic stance, marker of effective communication: agents will naturally co- construct a shared dyadic conveys interpersonal stance and is a particularly efficient sig- nal for co-regulation of communication

  16. 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…

  17. 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…

  18. 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…

  19. The Power of Practitioner Research and Development of an Inquiry Stance in Teacher Education Programs

    ERIC Educational Resources Information Center

    Wolkenhauer, Rachel; Boynton, Sylvia; Dana, Nancy Fichtman

    2011-01-01

    This article presents a framework for establishing inquiry as a foundation of a teacher education program to help prospective and practicing teachers view inquiry not as a project but as a stance. Cochran-Smith and Lytle (2009) assert that "working from an inquiry stance involves a continual process of making current arrangements problematic,…

  20. Three components of postural control associated with pushing in symmetrical and asymmetrical stance.

    PubMed

    Lee, Yun-Ju; Aruin, Alexander S

    2013-07-01

    A number of occupational and leisure activities that involve pushing are performed in symmetrical or asymmetrical stance. The goal of this study was to investigate early postural adjustments (EPAs), anticipatory postural adjustments (APAs), and compensatory postural adjustments (CPAs) during pushing performed while standing. Ten healthy volunteers stood in symmetrical stance (with feet parallel) or in asymmetrical stance (staggered stance with one foot forward) and were instructed to use both hands to push forward the handle of a pendulum attached to the ceiling. Bilateral EMG activity of the trunk and leg muscles and the center of pressure (COP) displacements in the anterior-posterior (AP) and medial-lateral (ML) directions were recorded and analyzed during the EPAs, APAs, and CPAs. The EMG activity and the COP displacement were different between the symmetrical and asymmetrical stance conditions. The COP displacements in the ML direction were significantly larger in staggered stance than in symmetrical stance. In staggered stance, the EPAs and APAs in the thigh muscles of the backward leg were significantly larger, and the CPAs were smaller than in the forward leg. There was no difference in the EMG activity of the trunk muscles between the stance conditions. The study outcome confirmed the existence of the three components of postural control (EPAs, APAs, and CPAs) in pushing. Moreover, standing asymmetrically was associated with asymmetrical patterns of EMG activity in the lower extremities reflecting the stance-related postural control during pushing. The study outcome provides a basis for studying postural control during other daily activities involving pushing. PMID:23727828

  1. Influence of enhanced visual feedback on postural control and spinal reflex modulation during stance

    Microsoft Academic Search

    Wolfgang Taube; Christian Leukel; Albert Gollhofer

    2008-01-01

    The present study assessed the influence of visual feedback on stance stability and soleus H-reflex excitability. The centre\\u000a of pressure (COP) displacement was measured in upright stance on a rigid surface (stable surface) and on a spinning top (unstable\\u000a surface) while subjects either received “normal” visual feedback (without laser pointer = WLP) or pointed with a laser pointer\\u000a on a target on

  2. SEEK Web tutor: fostering a critical stance while exploring the causes of volcanic eruption

    Microsoft Academic Search

    Arthur C. Graesser; Jennifer Wiley; Susan R. Goldman; Tenaha O’Reilly; Moongee Jeon; Bethany McDaniel

    2007-01-01

    We investigated the impact of a Web tutor on college students’ critical stance and learning while exploring Web pages on science.\\u000a Critical stance is an aspect of self-regulated learning that emphasizes the need to evaluate the truth and relevance of information\\u000a as the learner engages in systematic inquiry to answer challenging questions. The Web tutor is called SEEK, an acronym

  3. Walking with wider steps increases stance phase gluteus medius activity.

    PubMed

    Kubinski, Samantha N; McQueen, Christina A; Sittloh, Keir A; Dean, Jesse C

    2015-01-01

    Increases in step width have been reported for several clinical populations, including older adults and stroke survivors. These populations often also exhibit decreased hip abductor strength, suggesting that walking with wider steps may be an adaptive response in order to reduce the mechanical demands on the hip abductors. The purpose of this study was to quantify the relationship between step width and gluteus medius (GM) activity during walking. Fourteen young, uninjured adults walked on a treadmill at 1.25 m/s for four step width conditions (Normal, Narrow, Medium, and Wide) while step width and stance phase GM electromyographic (EMG) activity were quantified. We also measured hip abduction torque and GM activity during maximum voluntary isometric contractions (MVICs) at three hip angles (neutral, abducted 10°, and abducted 20°). During walking trials, GM activity was significantly (p < 0.0001) influenced by step width; compared to Normal walking, GM activity was 47% higher with Wide steps and 24% lower with Narrow steps. We also observed a weak positive correlation (r = 0.18 ± 0.14) between step width and GM activity during Normal walking, as GM activity was higher with wider steps. These results cannot be attributed to changes in GM conformation under the recording electrode, as GM activity was not influenced by hip angle during MVICs. The increased GM activity with wider steps does not support the proposal that increasing step width would be a beneficial adaptation to weakened hip abductors. A likely alternative explanation is that increased step width is a response to decreased gait balance. PMID:25300241

  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. Characteristics of temporal fluctuation of the vertical ground reaction force during quiet stance in Parkinson's disease.

    PubMed

    Minamisawa, Tadayoshi; Sawahata, Hirohito; Takakura, Kei; Yamaguchi, Takashi

    2012-02-01

    Stance instability is seen in late stage Parkinson's disease (PD). Stabilometer-based center-of-pressure (COP) evaluation is an easy, routine method for measuring postural control ability. Most of the stabilometer- and force plate-based studies on upright postural control have discussed horizontal COP component control. Previous studies on vertical component control have been few, and no fractal analysis-based study on the component has been reported. We aimed to show the influence of neurological changes and aging on the vertical component and the difference in fluctuation pattern behavior in healthy young and elderly subjects as well as Parkinsonian patients. Detrended fluctuation analysis was used to study characteristics of fluctuation of vertical ground reaction force. In the three groups, all scaling exponents (?, ?1, ?2), which are time-correlated data of vertical ground reaction force, had a value >0 and <0.5 (0

  6. Centre of pressure sway characteristics during static one-legged stance of athletes from different sports.

    PubMed

    Matsuda, Shigeki; Demura, Shinichi; Uchiyama, Masanobu

    2008-05-01

    The frequency of one-legged stance and two-legged stance differs considerably among sports. We therefore expect the balance ability of athletes from different sports to vary. This study compared the sway characteristics during a static one-legged stance of soccer players, basketball players, swimmers, and non-athletes. The centre of pressure sway during one-legged stance of ten male participants representing each of the four groups was measured using a stabilometer. Centre of pressure sway was assessed by four sway factors: sway velocity, anterior-posterior sway, horizontal sway, and high-frequency sway. None of the four groups of participants showed significant differences in body sway between standing on the dominant leg and standing on the non-dominant leg. The soccer players had more high-frequency sway and less anterior-posterior sway and horizontal sway than the basketball players, swimmers, and non-athletes. These results suggest that soccer players have superior ability to maintain a stable one-legged stance. Further study is required to determine how much of the superior balance ability in soccer players is innate and how much is developed through training, as well as to determine the relationship between balance ability and playing performance. PMID:18409108

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

    PubMed Central

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

    2010-01-01

    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) which 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. Normal rats pattern was to carry significantly more weight on the hindlimbs in quiet stance (~60%). Operate rats strategy of compensation for perturbations was entirely in forelimbs; as a result, the hind-limbs 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. EFL Doctoral Students' Conceptions of Authorial Stance in Academic Knowledge Claims and the Tie to Epistemic Beliefs

    ERIC Educational Resources Information Center

    Chang, Peichin; Tsai, Chin-Chung

    2014-01-01

    Taking an effective authorial stance in research argumentation has been designated as both vitally important and challenging. The study investigated English as a foreign language (EFL) doctoral students' conceptions of authorial stance, the role of domains in affecting their conceptions, and the ties of the conceptions to the…

  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. Abstract--This paper discusses the design of legged walking robots that are exactly constrained during the stance phase of

    E-print Network

    Dollar, Aaron M.

    during the stance phase of locomotion. Legged robots with a large number of actuated degrees of freedom, such robots can have multiple, controllable stance points for stabilizing the body. Kinematic legged walkers actuated to enable arbitrary reconfiguration of each leg relative to the body. However, once such robots

  12. 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…

  13. From Tununak to Beaufort: Taking a Critical Inquiry Stance as a First Year Teacher

    ERIC Educational Resources Information Center

    Fecho, Bob; Price, Kim; Read, Chris

    2004-01-01

    In this article, the authors show how two first year teachers a continent apart--Kim in the village of Tununak on the Bering Sea in Alaska and Chris in Beaufort, South Carolina, on the Atlantic Ocean--were able to take inquiry stances on their classrooms. In particular, through analysis of e-mails written in Chris' and Kim's first years of…

  14. 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

  15. 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…

  16. Afferent-mediated modulation of the soleus muscle activity during the stance phase of human walking

    Microsoft Academic Search

    Nazarena Mazzaro; Michael J. Grey; Omar Feix do Nascimento; Thomas Sinkjær

    2006-01-01

    The aim of this study was to investigate the contribution of proprioceptive feedback to the amplitude modulation of the soleus muscle activity during human walking. We have previously shown that slow-velocity, small-amplitude ankle dorsiflexion enhancements and reductions applied during the stance phase of the step cycle generate, respectively, increments and decrements on the ongoing soleus activity. We have also shown

  17. Doing Business in Nineteenth-Century Scotland: Expressing Authority, Conveying Stance

    Microsoft Academic Search

    MARINA DOSSENA

    2006-01-01

    Relying on examples taken from the business section of the Corpus of Nineteenth-Century Scottish Correspondence (in preparation), this paper intends to discuss the linguistic means employed to express authority and convey stance in relation to different recipients (peers, superiors, or subordinates) and different subject matters (e.g., legal controversy as opposed to ordinary, routine transactions). In particular, the aim is to

  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. Situating Relational Ontology and Transformative Activist Stance within the "Everyday" Practice of Coteaching and Cogenerative Dialogue

    ERIC Educational Resources Information Center

    Murphy, Colette; Carlisle, Karen

    2008-01-01

    This paper attempts to advance the thinking in Stetsenko's paper by situating the concepts of relational ontology and transformative activist stance in the context of coteaching and cogenerative dialogue. In so doing, we hope to make Stetsenko's ideas more operational in terms of access and application by researchers, teachers, policy makers and…

  20. 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…

  1. Ankle and Foot Kinematics Associated with Stage II PTTD During Stance

    PubMed Central

    Houck, Jeff R.; Neville, Christopher G.; Tome, Josh; Flemister, Adolph S.

    2010-01-01

    Background Subjects with stage II posterior tibial tendon dysfunction (PTTD) exhibit abnormal foot kinematics; however, how individual segment kinematics (hindfoot (HF) or first metatarsal (first MET) segments) influence global foot kinematics is unclear. The purpose of this study was to compare foot and ankle kinematics and sagittal plane HF and first MET segment kinematics between stage II PTTD and controls. Materials and Methods Thirty patients with stage II PTTD and 15 healthy controls were evaluated. Kinematic data from the tibia, calcaneus, and first MET were collected during walking using three dimensional motion analysis techniques. A threesegment foot model (HF, calcaneus; first MET, first metatarsal, and tibia) was used to calculate relative angles (ankle, HF relative to tibia; midfoot, first MET relative to HF) and segment angles (HF and first MET relative to the global). A mixed effect ANOVA model was utilized to compare angles between groups for each variable. Results Patients with PTTD showed greater ankle plantarflexion (p = 0.02) by 6.8 degrees to 8.4 degrees prior to or at 74% of stance; greater HF eversion (p < 0.01) across stance (mean difference = 4.5 degrees); and greater first MET dorsiflexion (p < 0.01) across stance (mean difference = 8.8 degrees). HF and first MET segment angles revealed greater HF dorsiflexion (p = 0.01) during early stance and greater first MET dorsiflexion (p = 0.001) across stance. Conclusion Abnormal HF and first MET segment kinematics separately influence both ankle and midfoot movement during walking in subjects with stage II PTTD. Clinical Relevance These abnormal kinematics may serve as another measure of response to clinical treatment and/or guide for clinical strategies (exercise, orthotics, and surgery) seeking to improve foot kinematics. PMID:19486631

  2. Evidence for beta corticomuscular coherence during human standing balance: Effects of stance width, vision, and support surface.

    PubMed

    Jacobs, J V; Wu, G; Kelly, K M

    2015-07-01

    The role of the cerebral cortex in maintaining human standing balance remains unclear. Beta corticomuscular coherence (CMC) provides a measure of communication between the sensory-motor cortex and muscle, but past literature has not demonstrated significant beta CMC during human stance. This study evaluated the effects of stance width, vision, and surface compliance on beta CMC during human stance using methods to enhance sensitivity to CMC. Ten healthy, young adults stood for three 60-s trials in each of a wide or narrow stance width while on a firm surface and in narrow stance on a foam surface, each with eyes open or closed. Beta CMC was calculated between contralateral electroencephalographic and electromyographic recordings. Electromyography was recorded from bilateral tibialis anterior and gastrocnemius lateralis muscles. CMC magnitude was defined as the average integrated area of coherence spectrum above a significance threshold. Measures of center-of-pressure (COP) sway were derived from force plates under the subjects' feet. Results of CMC from four muscles across six stance conditions (a total of 24 combinations) demonstrated significant average CMC magnitude from every subject in 20 combinations and significant average CMC magnitude in nine of 10 subjects in the remaining four combinations. The CMC magnitude was significantly larger in the wide-stance condition than in the narrow-stance condition with eyes open. No significant differences were detected when comparing eyes-open to eyes-closed conditions or when comparing firm- to foam-surface conditions. Correlations between CMC magnitude and COP sway elicited some significant relationships, but there was no consistent direction or pattern of correlation based on muscle or stance condition. Results demonstrate that significant beta CMC is evident during human standing balance, and that beta CMC is responsive to changes in mechanical, but not visual or surface, conditions. PMID:25869620

  3. ATAXIA OF STANCE IN DIFFERENT TYPES OF ALCOHOL DEPENDENCE — A POSTUROGRAPHIC STUDY

    Microsoft Academic Search

    Christian Wober; Cicek Wober-bingol; Andreas Karwautz; Amanda Nimmerrichter; Henriette Walter; Luder Deecke

    1998-01-01

    Abstract — The aim of this study was to assess the prevalence of ataxia of stance in different types of alcohol-dependent patients. Posturographic measurements,were,performed,in 82 abstinent alcohol- dependent,patients and 54 healthy controls in order to analyse postural control According to Lesch and co-workers, alcohol dependence was classified as total abstinence (Type I), drinking without loss of control (Type II), fluctuating

  4. TIBIOFEMORAL KINEMATICS AND CONDYLAR MOTION DURING THE STANCE PHASE OF GAIT

    PubMed Central

    Kozanek, Michal; Hosseini, Ali; Liu, Fang; Van de Velde, Samuel K.; Gill, Thomas J.; Rubash, Harry E.; Li, Guoan

    2009-01-01

    Accurate knowledge of the dynamic knee motion in vivo is instrumental for understanding normal and pathological function of the knee joint. However, interpreting motion of the knee joint during gait in other than the sagittal plane remains controversial. In this study, we utilized the dual fluoroscopic imaging technique to investigate the six-degree of freedom kinematics and condylar motion of the knee during the stance phase of treadmill gait in eight healthy volunteers at a speed of 0.67m/sec. We hypothesized that the 6DOF knee kinematics measured during gait will be different from those reported for non-weightbearing activities, especially with regards to the phenomenon of femoral rollback. In addition, we hypothesized that motion of the medial femoral condyle in the transverse plane is greater than that of the lateral femoral condyle during the stance phase of treadmill gait. The rotational motion and the anterior-posterior translation of the femur with respect to the tibia showed a clear relationship with the flexion-extension path of the knee during the stance phase. Additionally, we observed that the phenomenon of femoral rollback was reversed, with the femur noted to move posteriorly with extension and anteriorly with flexion. Furthermore, we noted that motion of the medial femoral condyle in the transverse plane was greater than that of the lateral femoral condyle during the stance phase of gait (17.4±2.0 mm vs. 7.4±6.1 mm, respectively; p<0.01). The trend was opposite to what has been observed during non-weightbearing flexion or single-leg lunge in previous studies. These data provide baseline knowledge for the understanding of normal physiology and for the analysis of pathological function of the knee joint during walking. These findings further demonstrate that knee kinematics is activity-dependent and motion patterns of one activity (non-weightbearing flexion or lunge) cannot be generalized to interpret a different one (gait). PMID:19497573

  5. HumanLike Walking using Toes Joint and Straight Stance Leg

    Microsoft Academic Search

    Sven Behnke

    This paper describes the use of an actuated toes joint in a humanoid robot to achieve human-like bipedal walking. The robot does not shorten the stance leg, but uses the segment between the ankle joint and the toes joint to over-extend the unloading leg in the double-support phase. Experiments with the servo-based humanoid robot Toni show that this approach leads

  6. Postural Instability Detection: Aging and the Complexity of Spatial-Temporal Distributional Patterns for Virtually Contacting the Stability Boundary in Human Stance

    PubMed Central

    Kilby, Melissa C.; Slobounov, Semyon M.; Newell, Karl M.

    2014-01-01

    Falls among the older population can severely restrict their functional mobility and even cause death. Therefore, it is crucial to understand the mechanisms and conditions that cause falls, for which it is important to develop a predictive model of falls. One critical quantity for postural instability detection and prediction is the instantaneous stability of quiet upright stance based on motion data. However, well-established measures in the field of motor control that quantify overall postural stability using center-of-pressure (COP) or center-of-mass (COM) fluctuations are inadequate predictors of instantaneous stability. For this reason, 2D COP/COM virtual-time-to-contact (VTC) is investigated to detect the postural stability deficits of healthy older people compared to young adults. VTC predicts the temporal safety margin to the functional stability boundary (?=? limits of the region of feasible COP or COM displacement) and, therefore, provides an index of the risk of losing postural stability. The spatial directions with increased instability were also determined using quantities of VTC that have not previously been considered. Further, Lempel-Ziv-Complexity (LZC), a measure suitable for on-line monitoring of stability/instability, was applied to explore the temporal structure or complexity of VTC and the predictability of future postural instability based on previous behavior. These features were examined as a function of age, vision and different load weighting on the legs. The primary findings showed that for old adults the stability boundary was contracted and VTC reduced. Furthermore, the complexity decreased with aging and the direction with highest postural instability also changed in aging compared to the young adults. The findings reveal the sensitivity of the time dependent properties of 2D VTC to the detection of postural instability in aging, availability of visual information and postural stance and potential applicability as a predictive model of postural instability during upright stance. PMID:25295589

  7. Latina mothers' stances on stimulant medication: complexity, conflict, and compromise.

    PubMed

    Arcia, Emily; Fernández, María C; Jáquez, Marisela

    2004-10-01

    This study was undertaken to understand and describe Latina mothers' cognitions and attitudes toward the use of medication for their young children's behavior problems under the premise that these factors are determinants of noncompliance and inadequate adherence to medication treatments. Quantitative and qualitative data were extracted from a multimethod study of professional help seeking. Participants were 62 mothers from Cuba, Puerto Rico, and the Dominican Republic. Findings indicated that mothers overwhelmingly preferred treatment options other than medication primarily because they understood medication to be addictive, dulling of cognitive processes, and inappropriate for behavior problems. Inadequate adherence was common and logically consistent with maternal cognitions. Maternal choices with respect to the use of medication were transactional and quite complex in nature and changed over time. The strongest agents in this process were schools and the mothers' immediate family. Implications for clinical practice are presented. PMID:15502547

  8. Field of view and base of support width influence postural responses to visual stimuli during quiet stance

    E-print Network

    Kenyon, Robert V.

    stance Jefferson W. Streepey a,*, Robert V. Kenyon b , Emily A. Keshner a,c a SMPP, Rehabilitation and whole body center of mass (COM) and ankle angle root mean square (RMS) were determined as were head

  9. Design and functional evaluation of a quasi-passive compliant stance control knee-ankle-foot orthosis.

    PubMed

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

    2014-03-01

    In this paper, we present the mechanical design, control algorithm, and functional evaluation of a quasi-passive compliant stance control knee-ankle-foot orthosis. The orthosis implements a spring in parallel with the knee joint during the stance phase of the gait and allows free rotation during the swing phase. The design is inspired by the moment-angle analysis of the knee joint revealing that the knee function approximates that of a linear torsional spring in the stance phase of the gait. Our orthosis aims to restore the natural function of a knee that is impaired by injury, stroke, post-polio, multiple sclerosis, spinal cord injury, patellofemoral pain syndrome, osteoarthritis, and others. Compared with state-of-the-art stance control orthoses, which rigidly lock the knee during the stance phase, the described orthosis intends to provide the natural shock absorption function of the knee in order to reduce compensatory movements both in the affected and unaffected limbs. Preliminary testing on three unimpaired subjects showed that compliant support of the knee provided by the orthosis explained here results in higher gait speed as well as more natural kinematic profiles for the lower extremities when compared with rigid support of the knee provided by an advanced commercial stance control orthosis. PMID:24608684

  10. Tensile Engagement of the Peri-Ankle Ligaments in Stance Phase

    PubMed Central

    Tochigi, Yuki; Rudert, M. James; Amendola, Annunziato; Brown, Thomas D.; Saltzman, Charles L.

    2008-01-01

    Background The efficacy of reconstructive surgical procedures that attempt to restore normal ankle kinematics theoretically requires a full biomechanical understanding of the natural human ankle during gait. The contribution of the peri-ankle ligaments versus the articular surfaces to ankle motion control is not yet well understood. Knowledge of the tensile engagement of the peri-ankle ligaments during stance phase is necessary in order to achieve physiologic motion patterns. Methods Eleven fresh-frozen cadaver ankles were subjected to a dynamic loading sequence simulating the stance phase of normal level gait. Simultaneously, ligament strain was continuously monitored in the anterior talofibular, calcaneofibular, and posterior talofibular ligaments, as well as in the anterior, middle, and posterior superficial deltoid ligaments. Eight of these specimens underwent further quasi-static range of motion testing, where ligament tension recruitment was assessed at 30° plantar flexion and 30° dorsiflexion. Results In the dynamic loading tests, none of the ligaments monitored showed a reproducible strain pattern consistent with playing a role in ankle stabilization. However, in the extended range of motion tests, most ligaments were often taut in plantar flexion or dorsiflexion. Conclusions A consistent combination of individual ligament strain patterns that principally control ankle motion was not manifest; rather, none of the ligaments under study were reproducibly recruited to be a primary stabilizing structure. The peri-ankle ligaments are likely to be secondary restraining structures that serve to resist motion, to avoid extreme positions. Stance phase ankle motion appears to be primarily controlled by articular congruity, not by peri-ankle ligament tension. Clinical Relevance Reconstructive ankle surgeries which aim to restore normal kinematics should focus on optimizing motion control by means of the articulating surface topography, rather than relying substantially on ligamentous guidance. PMID:16390641

  11. Automatic postural responses in the cat: responses of distal hindlimb muscles to paired vertical perturbations of stance.

    PubMed

    Rushmer, D S; Dunbar, D C; Russell, C J; Windus, S L

    1987-01-01

    The active components of the quadrupedal diagonal stance response to rapid removal of the support from beneath a single limb were studied in cats to further define the mechanisms that trigger and generate the response. We recorded EMG activity from lateral gastrocnemius and tibialis anterior muscles in awake, behaving cats while they stood on an hydraulic posture platform. By dropping the support from beneath a single limb, we evoked the diagonal stance response, with its characteristic changes in vertical force and EMG patterns. As the animal responded to this drop, a second perturbation of posture was then presented at intervals of 10 to 100 ms following the first. The second perturbation, which consisted of dropping the support from beneath the two limbs that were loaded as a result of the initial limb drop, made the first response biomechanically inappropriate. The EMG responses observed in both muscles during paired perturbations were triggered by the somatosensory events related to the perturbations. Muscle responses that were appropriate for the first perturbation always occurred with amplitudes and latencies similar to control trials. This was true even when the second perturbation occurred 10-20 ms after the first, that is, when this perturbation either preceded or was coincident with the response to the initial limb drop. The EMG responses that were normally associated with the second perturbation were delayed and/or reduced in amplitude when the time interval between perturbations was short. As the inter-perturbation interval was lengthened beyond 60-100 ms, however, EMG responses to the second perturbation were unaffected by the occurrence of the first perturbation. When the hindlimb containing the recording electrodes was dropped as part of the second perturbation, a myotatic latency response was observed in tibialis anterior. The amplitude of this response to the second perturbation was greater than controls when this displacement was presented during the period between initiation of the first perturbation and execution of the response to it. When the second displacement was presented after execution of the first response began, the amplitude of the myotatic response was reduced below control levels. While the results do not preclude the possibility that these "automatic" postural responses are segmental or suprasegmental reflexes, they support the hypothesis that the active component of the response to drop of the support beneath a single limb is centrally programmed and that the appropriate response can be triggered very rapidly by the somatosensory information signalling the perturbation. PMID:3691720

  12. The shifting of the torsion axis of the foot during the stance phase of lateral cutting movements.

    PubMed

    Graf, Eveline S; Stefanyshyn, Darren J

    2012-10-11

    Previously, foot torsion has been studied with respect to peak angles during athletic movements. Athletic footwear often contains a torsion element that dictates a torsion axis of the shoe. The location of the axis of rotation of the foot is, however, unknown. Therefore, the purpose of this study was to describe the torsion axis location during the stance phase of lateral cutting movements. Thirty-nine subjects performed a barefoot lateral jab and 19 subjects performed a barefoot shuffle cut. Markers were placed on the fore- and rearfoot and their movement was quantified using a 3-D video system. The torsion axis location was determined using a modified finite helical axis approach during the stance phase while the torsion angle was calculated as the amount of rotation around the torsion axis. At the beginning of the stance phase, the axis was located on the medial aspect of the foot. During the stance phase, the axis shifted towards the lateral side of the foot before the axis moved back to the medial aspect of the foot at the end of stance. For both movements significant correlations between the axis location in the vertical and medio-lateral directions and the torsion angle were found. With larger torsion (forefoot inversion) angles the axis was in a more lateral and plantar location within the foot. With this knowledge, a shoe torsion system where the shoe torsion axis location is in agreement with the foot axis location could be developed. PMID:22959787

  13. 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

  14. TENS to the lateral aspect of the knees during stance attenuates postural sway in young adults.

    PubMed

    Laufer, Yocheved; Dickstein, Ruth

    2007-01-01

    Somatosensory input is known to be essential for postural control. The present study examined the effects on postural sway of sensory input delivered via transcutaneous electrical nerve stimulation (TENS) applied to the knees during stance. Electrodes from a dual-channel portable TENS unit were adhered to the skin overlying the lateral and medial aspect of both knees of 20 young healthy volunteers (mean age 24.0 years, standard deviation 4.0). Postural sway parameters were obtained during static bipedal stance with an AMTI force platform. Four stimulation conditions were tested with eyes open and with eyes closed: no TENS; TENS applied bilaterally; and TENS applied to either the right or the left knee. Participants underwent two eight-trial blocks, with each trial lasting 30 seconds. The order of conditions was randomized for each participant. Stimulation consisted of a biphasic symmetrical stimulus delivered at the sensory detection level, with a pulse duration of 200microsec and a pulse frequency of 100Hz. The application of TENS induced significant reductions in mean sway velocity and in the medio-lateral dispersion of the center of pressure, with no corresponding effect on the anterior-posterior dispersion. These findings suggest that electrical stimulation delivered at the sensory detection level to the lateral aspects of the knees may be effective in improving balance control, and that this effect may be directionally specific. PMID:18060330

  15. TENS to the posterior aspect of the legs decreases postural sway during stance.

    PubMed

    Dickstein, Ruth; Laufer, Yocheved; Katz, Miri

    2006-01-23

    The purpose of this study was to examine the effect of Transcutaneous Electrical Nerve Stimulation (TENS) applied to the posterior aspect of the legs, on postural sway during stance. Thirty healthy subjects were tested while standing on a force platform under four stimulation conditions: no TENS, bilateral TENS, and unilateral left and right TENS. Thirty-second long tests, employing detection threshold amplitudes, were performed in three blocks. In each block, the four conditions were applied both with and without vision in a random order. The results indicate that the application of TENS brought about a decrease in postural sway as expressed by average sway velocity, in addition to a decrease in the absolute values of maximal and minimal medio-lateral and anterior-posterior velocity. Thus, similar to sub-threshold random electrical noise, it appears that the application of low-amplitude TENS to the lower limbs decreases postural sway during stance. Considering the ease of TENS application and the high prevalence of postural disorders, the potential clinical significance of this observation is to be determined by further studies. PMID:16207512

  16. The Effect of Continuous and Discretized Presentations of Concurrent Augmented Visual Biofeedback on Postural Control in Quiet Stance

    PubMed Central

    D’Anna, Carmen; Schmid, Maurizio; Bibbo, Daniele; Bertollo, Maurizio; Comani, Silvia; Conforto, Silvia

    2015-01-01

    The purpose of this study was to evaluate the effect of a continuous and a discretized Visual Biofeedback (VBF) on balance performance in upright stance. The coordinates of the Centre of Pressure (CoP), extracted from a force plate, were processed in real-time to implement the two VBFs, administered to two groups of 12 healthy participants. In the first group, a representation of the CoP was continuously shown, while in the second group, the discretized VBF was provided at an irregular frequency (that depended on the subject's performance) by displaying one out of a set of five different emoticons, each corresponding to a specific area covered by the current position of the CoP. In the first case, participants were asked to maintain a white spot within a given square area, whereas in the second case they were asked to keep the smiling emoticon on. Trials with no VBF were administered as control. The effect of the two VBFs on balance was studied through classical postural parameters and a subset of stabilogram diffusion coefficients. To quantify the amount of time spent in stable conditions, the percentage of time during which the CoP was inside the stability area was calculated. Both VBFs improved balance maintainance as compared to the absence of any VBF. As compared to the continuous VBF, in the discretized VBF a significant decrease of sway path, diffusion and Hurst coefficients was found. These results seem to indicate that a discretized VBF favours a more natural postural behaviour by promoting a natural intermittent postural control strategy. PMID:26196518

  17. 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

  18. 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

  19. Adaptive behaviour of the spinal cord in the transition from quiet stance to walking

    PubMed Central

    2012-01-01

    Background Modulation of nociceptive withdrawal reflex (NWR) excitability was evaluated during gait initiation in 10 healthy subjects to investigate how load- and movement-related joint inputs activate lower spinal centres in the transition from quiet stance to walking. A motion analysis system integrated with a surface EMG device was used to acquire kinematic, kinetic and EMG variables. Starting from a quiet stance, subjects were asked to walk forward, at their natural speed. The sural nerve was stimulated and EMG responses were recorded from major hip, knee and ankle muscles. Gait initiation was divided into four subphases based on centre of pressure and centre of mass behaviours, while joint displacements were used to categorise joint motion as flexion or extension. The reflex parameters were measured and compared between subphases and in relation to the joint kinematics. Results The NWR was found to be subphase-dependent. NWR excitability was increased in the hip and knee flexor muscles of the starting leg, just prior to the occurrence of any movement, and in the knee flexor muscles of the same leg as soon as it was unloaded. The NWR was hip joint kinematics-dependent in a crossed manner. The excitability of the reflex was enhanced in the extensor muscles of the standing leg during the hip flexion of the starting leg, and in the hip flexors of the standing leg during the hip extension of the starting leg. No notable reflex modulation was observed in the ankle muscles. Conclusions Our findings show that the NWR is modulated during the gait initiation phase. Leg unloading and hip joint motion are the main sources of the observed modulation and work in concert to prepare and assist the starting leg in the first step while supporting the contralateral leg, thereby possibly predisposing the lower limbs to the cyclical pattern of walking. PMID:22800397

  20. 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

  1. 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.

  2. COORDINATED, MULTI-JOINT, FATIGUE-RESISTANT FELINE STANCE PRODUCED WITH INTRAFASCICULAR HIND LIMB NERVE STIMULATION

    PubMed Central

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

    2012-01-01

    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 bi-articular. 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. PMID:22414699

  3. Effects of plantar cutaneo-muscular and tendon vibration on posture and balance during quiet and perturbed stance

    Microsoft Academic Search

    Cynthia Thompson; Marc Bélanger; Joyce Fung

    2011-01-01

    Modulation of lower limb somatosensory information by tendon or plantar vibration produces directionally specific, vibration-induced falling reactions that depend on the tendon or the region of the sole that is vibrated. This study characterized the effects of different patterns of plantar cutaneo-muscular vibration and bilateral Achilles tendon vibration (ATV) on the postural strategies observed during quiet and perturbed stance. Twelve

  4. 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…

  5. Government Stance and Internal Diversity of Protest: A Comparative Study of Protest against the War in Iraq in Eight Countries

    ERIC Educational Resources Information Center

    Walgrave, Stefaan; Verhulst, Joris

    2009-01-01

    This study tackles the question to what extent the composition of protest events is determined by the stance of governments. Established contextual theories do not formulate propositions on how context affects individual protesters. The article engages in empirically testing whether the macro-context affects the internal diversity of the crowds…

  6. Human stance stability improves with the repetition of the task: effect of foot position and visual condition

    Microsoft Academic Search

    Jessica Tarantola; Antonio Nardone; Elena Tacchini; Marco Schieppati

    1997-01-01

    The effects of repetition of quiet stance trials on body sway, recorded through a stabilometric platform, were studied in 12 normal subjects. With feet together, both with eyes open (EO) and closed (EC), a progressive shift forward of the centre of foot pressure (CFP) occurred with repetition. In addition, with EC, but not with EO, a significant progressive reduction in

  7. Automatic postural responses in the cat: responses of distal hindlimb muscles to paired vertical perturbations of stance

    Microsoft Academic Search

    D. S. Rushmer; D. C. Dunbar; C. J. Russell; S. L. Windus

    1987-01-01

    The active components of the quadrupedal diagonal stance response to rapid removal of the support from beneath a single limb were studied in cats to further define the mechanisms that trigger and generate the response. We recorded EMG activity from lateral gastrocnemius and tibialis anterior muscles in awake, behaving cats while they stood on an hydraulic posture platform. By dropping

  8. Participation in Peer Response as Activity: An Examination of Peer Response Stances from an Activity Theory Perspective

    ERIC Educational Resources Information Center

    Zhu, Wei; Mitchell, Deborah A.

    2012-01-01

    This article reports a case study that examined English as a Second Language students' peer response stances from an activity theory perspective. More specifically, the study was guided by the constructs of activity and motive/object in Leont'ev's theory. Multiple sources of data were collected from two native Spanish-speaking students enrolled in…

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

    E-print Network

    Newby, Gregory B.

    in information system development. 1. Introduction: The Human Aspects of Cognitive Space Many groupsCognitive 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

  10. 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

  11. 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.

  12. The effects of ankle loads on balance ability during one-leg stance

    PubMed Central

    Jung, Da-eun; Kim, Kyoung

    2015-01-01

    [Purpose] The purpose of this study was to evaluate the effects of ankle loads on balance ability and to suggest an appropriate load amount. [Subjects and Methods] The 31 healthy subjects randomly put 0%, 1%, and 2% body weight loads on their ankles using a strap, and limit of stability was measured using a Biorescue system. Limits of stability were measured for 10 seconds using their dominant leg in the left, right, forward, and backward directions. [Results] All values for limit of stability increased significantly with the 1% load compared with the 0% load during a one-leg stance. However, all values except for the backward limit of stability showed a significant decrease with the 2% load compared with the 1% load. There was a significant difference between the 0% and 2% loads. [Conclusion] Application of loads on the ankles can be used as a training method for improving balance ability, and to increase efficiency, it is appropriate to apply 1% of the subject’s body weight.

  13. Enhancing stance phase propulsion during level walking by combining FES with a powered exoskeleton for persons with paraplegia.

    PubMed

    Ha, Kevin H; Quintero, Hugo A; Farris, Ryan J; Goldfarb, Michael

    2012-01-01

    This paper describes the design and implementation of a cooperative controller that combines functional electrical stimulation (FES) with a powered lower limb exoskeleton to provide enhanced hip extension during the stance phase of walking in persons with paraplegia. The controller utilizes two sources of actuation: the electric motors of the powered exoskeleton and the user's machine (FSM), a set of FES. It consists of a finite-state machine (FSM), a set of proportional-derivative (PD) controllers for the exoskeleton and a cycle-to-cycle adaptive controller for muscle stimulation. Level ground walking is conducted on a single subject with complete T10 paraplegia. Results show a 34% reduction in electrical power requirements at the hip joints during the stance phase of the gait cycle with the cooperative controller compared to using electric motors alone. PMID:23365900

  14. Enhancing Stance Phase Propulsion during Level Walking by Combining FES with a Powered Exoskeleton for Persons with Paraplegia*

    PubMed Central

    Ha, Kevin H.; Quintero, Hugo A.; Farris, Ryan J.; Goldfarb, Michael

    2013-01-01

    This paper describes the design and implementation of a cooperative controller that combines functional electrical stimulation (FES) with a powered lower limb exoskeleton to provide enhanced hip extension during the stance phase of walking in persons with paraplegia. The controller utilizes two sources of actuation: the electric motors of the powered exoskeleton and the user’s hamstrings activated by FES. It consists of a finite-state machine (FSM), a set of proportional-derivative (PD) controllers for the exoskeleton and a cycle-to-cycle adaptive controller for muscle stimulation. Level ground walking is conducted on a single subject with complete T10 paraplegia. Results show a 34% reduction in electrical power requirements at the hip joints during the stance phase of the gait cycle with the cooperative controller compared to using electric motors alone. PMID:23365900

  15. 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

  16. On the Use of Shadows in Stance Recovery Alfred M. Bruckstein \\Lambda Robert J. Holt Yves D. Jean Arun N. Netravali

    E-print Network

    Bruckstein, Alfred M.

    On the Use of Shadows in Stance Recovery Alfred M. Bruckstein \\Lambda Robert J. Holt Yves D. Jean, Mamassian, and Kersten (1997), contains a nice summary of the geometric issues involved in shadow formation

  17. Estimation of quasi-stiffness of the human hip in the stance phase of walking.

    PubMed

    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 (R(2)?=?92%) and flexion portions (R(2)?=?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

  18. 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

  19. Diabetic neuropathy and surface sway-referencing disrupt somatosensory information for postural stability in stance.

    PubMed

    Horak, Fay B; Dickstein, Ruth; Peterka, Robert J

    2002-01-01

    In order to determine the type of somatosensory information for postural control that is most affected by neuropathy, we compared the relative effects of three methods of sway-referencing the surface in a group of subjects with profound loss of somatosensory function associated with sensory polyneuropathy from diabetes with age-matched control subjects. Sway-referencing disrupted somatosensory feedback for postural control by servo-controlling the dorsi- and plantar-flexion rotation of the support surface in proportion to anterior-posterior excursion of (1) ankle angle, (2) center of body mass (CoM) angle or (3) filtered center of pressure (CoP). Postural sway in subjects with somatosensory loss was significantly larger than normal on a firm surface but not on the sway-referenced surfaces, suggesting that sway-referencing disrupts somatosensory information for postural control already disrupted by neuropathy. Control subjects standing on any sway-referenced surface swayed significantly more than neuropathy subjects who stood on a firm surface, suggesting that sway-referencing disrupts more somatosensory information than disrupted by severe neuropathy. CoP sway-referencing was less sensitive than ankle or CoM sway-referencing for distinguishing postural sway in subjects with somatosensory loss from age-matched control subjects. Given that filtered CoP sway-referencing disrupts the ability to utilize somatosensory information related to surface reactive force to a greater extent than the other two methods of sway-referencing, then these results support the hypothesis that subjects with diabetic peripheral neuropathy have lost more CoP information, than ankle or CoM angle information, for controlling postural sway in stance. PMID:12590833

  20. Recalibration of somesthetic plantar information in the control of undisturbed upright stance maintenance.

    PubMed

    Bernard-Demanze, L; Burdet, C; Berger, L; Rougier, P

    2004-12-01

    To assess the effects of changes in somesthetic plantar information on upright quiet stance, a rotary plantar massage was applied under the feet of healthy subjects for ten minutes. The controlling variable, the centre of pressure (CP) displacements, were recorded, before and after massage, through a force platform and decomposed into two elementary motions: the vertical projection of the centre of gravity (CG(v)) and the difference between the latter and the CP (CP-CG(v)) along medio-lateral ML and antero-posterior AP directions. These motions were processed through frequency analysis and modelled as fractional Brownian motion. For CP-CG(v) motions, the frequency analysis shows that massage under the plantar soles induces a decrease of the amplitudes along the ML direction suggesting reduced overall muscular activity (abductor-adductor muscles of the hip according to Winter et al.). A general trend is that the CG(v) amplitudes are also diminished after massage especially in the ML direction, indicating a better distribution of the body weight on the two supports. On the other hand, the effects tend to vanish after about 8 minutes. Conversely, when the massage was given under the toes, no particular effect on any elementary motion was observed, suggesting that the plantar mechanoreceptors under the toes necessitate stronger stimulation to respond significantly and/or that the greater sensitivity obtained was not used by the CNS. Overall, this data emphasises the fact that a recalibration of somesthetic cues may occur when enhanced afferent information is fed to the postural system. PMID:15657978

  1. Trains of electrical stimulation of the trapezius muscles redistribute the frequencies of body oscillations during stance.

    PubMed

    Nhouvannasak, V; Clément, S; Manto, M

    2015-09-01

    We investigated the postural effects of trains of electrical stimulation (TES) applied unilaterally or bilaterally on the trapezius muscle in 20 healthy subjects (mean age: 23.1?±?1.33?years; F/M: 8/12). The anterior-posterior (AP) displacements (AP axis), medio-lateral displacements (ML axis) and total travelled distances (TTW) of the centre of pressure (COP) remained unchanged with TES. However, detailed spectral analysis of COP oscillations revealed a marked decrease of the magnitudes of peak power spectral density (peak PSD) following application of TES. Peak PSD was highly correlated with the intensity of stimulation (P?0.30) and the integrals of the sub-band 8-10?Hz were significantly increased (P?stance. Previous studies have shown that patients with supra-tentorial stroke show an increased peak PSD in low frequencies of body oscillations. Therefore, our findings provide a rationale to assess neurostimulation of the trapezius muscle in the rehabilitation of postural deficits in supra-tentorial stroke. PMID:26004862

  2. Interrater Reproducibility of Knee Movement Analyses during the Stance Phase: Use of Anatomical Landmark Calibration with a Rigid Marker Set

    PubMed Central

    Fukaya, Takashi; Mutsuzaki, Hirotaka; Wadano, Yasuyoshi

    2013-01-01

    Objective. Measurements of knee joint movement in gait analysis may result in large errors caused by misplacement of reflective markers by the testers. To properly understand the measurement results, it is important to guarantee the reliability of the measurement method used for the purpose. The aim of this study was to confirm the interrater reproducibility of a measurement method with a rigid marker set (RMS). Methods. The study subjects were four healthy adults, and the testers were three physical therapists. The interrater reproducibility of the measurements was verified by using the coefficient of multiple correlations (CMCs) and the standard error of measurement (SEM). Results. The average CMCs values of 4 subjects in knee joint movement at the stance phase were greater than 0.8, and the average SEM values of 4 subjects in knee joint movement at the stance phase were also relatively good (maximum error: 2.42°). Conclusion. Based on these results, the measurement method with estimation of anatomical landmarks using the RMS can prevent misplacement during attachment of the reflective markers, as long as the testers have sufficient experience in attaching reflective markers. PMID:24222855

  3. 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

  4. Rethinking "Impact": Between the Attention Economy and the Readerless Republic of Letters , SubStance n 130, vol 42:1, 2013, p. 69-81.

    E-print Network

    Paris-Sud XI, Université de

    « Rethinking "Impact": Between the Attention Economy and the Readerless Republic of Letters », SubStance n° 130, vol 42:1, 2013, p. 69-81. Yves Citton Rethinking "Impact" between the Attention Economy. 1. It's the economy, stupid! "`Impact' is the buzzword of the day", Martha Nussbaum recently wrote

  5. Republicans change tune for Hispanic votes Mitt Romney and Newt Gingrich are softening their stance on immigration issues in an attempt to be more

    E-print Network

    Belogay, Eugene A.

    be detrimental to the Republican Party, according to former Florida governor Jeb Bush. "If we ignoreRepublicans change tune for Hispanic votes Mitt Romney and Newt Gingrich are softening their stance, Florida - It is just three days before the crucial Florida Republican primary and former Massachusetts

  6. 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

  7. Talk and Conceptual Change at Work: Adequate Representation and Epistemic Stance in a Comparative Analysis of Statistical Consulting and Teacher Workgroups

    ERIC Educational Resources Information Center

    Hall, Rogers; Horn, Ilana Seidel

    2012-01-01

    In this article we ask how concepts that organize work in two professional disciplines change during moments of consultation, which represent concerted efforts by participants to work differently now and in the future. Our analysis compares structures of talk, the adequacy of representations of practice, and epistemic and moral stances deployed…

  8. Issues in Discipline-Based Art Education: Strengthening the Stance, Extending the Horizons. Seminar Proceedings (Cincinnati, Ohio, May 21-24, 1987).

    ERIC Educational Resources Information Center

    Getty Center for Education in the Arts, Los Angeles, CA.

    The rationale for this seminar was to strengthen the discipline-based art education (DBAE) stance and extend its horizons. The format of the proceedings featured a speaker followed by a respondent and group discussions on each of the four issues addressed by the seminar. Dennie Wolf explained how current research in child development and cognitive…

  9. "The Mystery . . .": A Corpus-based Study of the Use of Nouns To Construct Stance in Theses from Two Contrasting Disciplines.

    ERIC Educational Resources Information Center

    Charles, Maggie

    2003-01-01

    Investigates the construction of stance through nouns in two corpora of theses--200,000 words in politics and international relations and 300,000 words in materials science. Examines nouns that are preceded by sentence initial deicitic "This" and that serve to encapsulate earlier prepositions. (Author/VWL)

  10. The influence of visual information on multi-muscle control during quiet stance: a spectral analysis approach.

    PubMed

    Danna-Dos-Santos, Alessander; Degani, Adriana M; Boonstra, Tjeerd W; Mochizuki, Luis; Harney, Allison M; Schmeckpeper, Megan M; Tabor, Lori C; Leonard, Charles T

    2015-02-01

    Standing upright requires the coordination of neural drives to a large set of muscles involved in controlling human bipedal stance (i.e., postural muscles). The coordination may deteriorate in situations where standing is performed under more challenging circumstances, such as standing on a smaller base of support or not having adequate visual information. The present study investigates the role of common neural inputs in the organization of multi-muscle synergies and the effects of visual input disruption to this mechanism of control. We analyzed the strength and distribution of correlated neural inputs (measured by intermuscular coherence) to six postural muscles previously recognized as components of synergistic groups involved in the maintenance of the body's vertical positioning. Two experimental conditions were studied: quiet bipedal stance performed with opened eyes (OEs) and closed eyes (CEs). Nine participants stood quietly for 30 s while the activity of the soleus, biceps femoris, lumbar erector spinae, tibialis anterior, rectus femoris, and rectus abdominis muscles were recorded using surface electrodes. Intermuscular (EMG-EMG) coherence was estimated for 12 muscle pairs formed by these muscles, including pairs formed solely by either posterior, anterior, or mixed (one posterior and one anterior) muscles. Intermuscular coherence was only found to be significant for muscle pairs formed solely by either posterior or anterior muscles, and no significant coherence was found for mixed muscle pairs. Significant intermuscular coherence was only found within a distinct frequency interval bounded between 1 and 10 Hz when visual input was available (OEs trials). The strength of correlated neural inputs was similar across muscle pairs located in different joints but executing a similar function (pushing body either backward or forward) suggesting that synergistic postural groups are likely formed based on their functional role instead of their anatomical location. Absence of visual information caused a significant decrease in intermuscular coherence. These findings are consistent with the hypothesis that correlated neural inputs are a mechanism used by the CNS to assemble synergistic muscle groups. Further, this mechanism is affected by interruption of visual input. PMID:25407521

  11. Evaluative Decision-Making for High-Quality Professional Development: Cultivating an Evaluative Stance

    ERIC Educational Resources Information Center

    Sumsion, Jennifer; Lunn Brownlee, Joanne; Ryan, Sharon; Walsh, Kerryann; Farrell, Ann; Irvine, Susan; Mulhearn, Gerry; Berthelsen, Donna

    2015-01-01

    Unprecedented policy attention to early childhood education internationally has highlighted the crucial need for a skilled early years workforce. Consequently, professional development of early years educators has become a global policy imperative. At the same time, many maintain that professional development research has reached an impasse. In…

  12. Effects of backpack carriage on foot-ground relationship in children during upright stance.

    PubMed

    Pau, Massimiliano; Corona, Federica; Leban, Bruno; Pau, Marco

    2011-02-01

    Although the scientific community widely recognizes that backpack carriage in primary school children represents a critical issue, its consequences in terms of postural alterations and possible onset of musculoskeletal pathologies are still not fully understood. In particular, little information is available on the way load carriage modifies the foot-ground relationship in terms of plantar pressure distribution. This issue is of particular relevance, because the presence of a load alters the physiological weightbearing functions and, when mechanical overloading is repeated in time, it can act as a co-factor in promoting foot discomfort or pain. On the basis of these considerations, this study analyzed plantar pressure maps of 359 children attending primary schools (6-10 years old) under static upright posture conditions, to assess the magnitude and features of effects originated by load carriage on the foot-ground relationship. The collected data showed that backpack introduces significant increases in overall contact area (up to 10%) and in the plantar pressure peaks in midfoot and forefoot regions (20-30%). A significant shift in the average position of the center of pressure towards the forefoot was also observed, as an indicator of the body's attempt to restore the initial balance conditions threatened by the load. These results suggest that heavy loads, in the case of significant exposure times, may increase the risk of foot discomfort and act as a co-factor in the onset of foot structure alterations or pathologies. PMID:21112213

  13. Fractal Parallelism: Solving SAT in bounded space and time

    E-print Network

    Duchier, Denys

    - like curves, black holes. . . ) [Pun, 2001, Brun, 2003, Etesi and Németi, 2002]. However, oftentimesFractal Parallelism: Solving SAT in bounded space and time Denys Duchier, Jérôme Durand problem, in- stance of SAT, can be solved in bounded space and time with simple geometrical constructions

  14. An analysis of directional changes in the center of pressure trajectory during stance.

    PubMed

    Nagano, Akinori; Noritake, Hisahito; Luo, Zhi-Wei

    2010-03-01

    This study proposes a new approach of posturography analysis, which enables the evaluation of directional changes in the center of pressure trajectory. The concept is similar to that of so-called "stabilogram diffusion analysis". Instead of calculating the distance traveled by the center of pressure in a certain time interval, this new method calculates the cosine of the instantaneous velocity vectors of the center of pressure, which corresponds to the amount of change in the sway direction (cosine=1 corresponds to the identical direction; cosine=-1 corresponds to the opposite direction). This method was applied to the analysis of the experimental data in which postural sway was collected under four conditions: open eyes, closed eyes, and two auditory biofeedback conditions. In the biofeedback conditions, auditory signal was given to the subjects when the center of pressure swayed out of a certain area. As results, the differences in the postural reaction under these conditions were clearly shown using the new method. The results indicated that the subjects reacted to the auditory signals by swaying in the opposite direction with biofeedback. It was also found that the eyes open condition exhibited a more random-like profile. As this method analyzes the directional change in the postural sway, this method can be utilized cooperatively together with such a method as stabilogram diffusion analysis, which analyzes the magnitude of sway. PMID:20138766

  15. 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.

  16. 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

  17. 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

  18. Effects of interactive video-game based system exercise on the balance of the elderly.

    PubMed

    Lai, Chien-Hung; Peng, Chih-Wei; Chen, Yu-Luen; Huang, Ching-Ping; Hsiao, Yu-Ling; Chen, Shih-Ching

    2013-04-01

    This study evaluated the effects of interactive video-game based (IVGB) training on the balance of older adults. The participants of the study included 30 community-living persons over the age of 65. The participants were divided into 2 groups. Group A underwent IVGB training for 6 weeks and received no intervention in the following 6 weeks. Group B received no intervention during the first 6 weeks and then participated in training in the following 6 weeks. After IVGB intervention, both groups showed improved balance based on the results from the following tests: the Berg Balance Scale (BBS), Modified Falls Efficacy Scale (MFES), Timed Up and Go (TUG) test, and the Sway Velocity (SV) test (assessing bipedal stance center pressure with eyes open and closed). Results from the Sway Area (SA) test (assessing bipedal stance center pressure with eyes open and closed) revealed a significant improvement in Group B after IVGB training. Group A retained some training effects after 6 weeks without IVGB intervention. Additionally, a moderate association emerged between the Xavix measured step system stepping tests and BBS, MFES, Unipedal Stance test, and TUG test measurements. In conclusion, IVGB training improves balance after 6 weeks of implementation, and the beneficial effects partially remain after training is complete. Further investigation is required to determine if this training is superior to traditional physical therapy. PMID:23177921

  19. A three-dimensional kinematic and dynamic study of the lower limb during the stance phase of gait using an homogeneous matrix approach.

    PubMed

    Doriot, Nathalie; Chèze, Laurence

    2004-01-01

    This paper presents a method to analyze three dimensional kinematics and dynamics of lower limb during walking. The proposed method is based on a homogeneous matrix concept, derived from robotics and using compact, expressive notation convenient for computer applications. The major advantage of this method is that no hypothesis is required on the joint model, which makes it applicable to complex and pathologic joints. Kinematic data are computed from 3-D trajectories of markers collected by a motion analysis system. External forces applied on the leg are measured synchronously during the stance phase of gait. Angular velocity components obtained using the homogeneous matrix method are displayed for three subjects and compared with those obtained from the same experimental data using a helical axis method. Then, intersegmental moments calculated from the inverse dynamic part of the homogeneous matrix method are shown on the same subjects. Kinematic results indicate that there are no significant differences between the methods, thus demonstrating the reproducibility of the stance phase of gait in the sagittal plane. Use of this synthetic homogeneous method developed for both kinematics and dynamics of rigid bodies demonstrates good promise for applications in biomechanics. PMID:14723490

  20. Times

    NSDL National Science Digital Library

    In this activity learners explore the connections of digital time displays with numeric and geometric properties. Students look for times that have bilateral or rotational symmetry, or have a certain digital sum, etc. Ideas for implementation, extension and support are included.

  1. 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

  2. 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

  3. Dynamic 3D scanning as a markerless method to calculate multi-segment foot kinematics during stance phase: methodology and first application.

    PubMed

    Van den Herrewegen, Inge; Cuppens, Kris; Broeckx, Mario; Barisch-Fritz, Bettina; Vander Sloten, Jos; Leardini, Alberto; Peeraer, Louis

    2014-08-22

    Multi-segmental foot kinematics have been analyzed by means of optical marker-sets or by means of inertial sensors, but never by markerless dynamic 3D scanning (D3DScanning). The use of D3DScans implies a radically different approach for the construction of the multi-segment foot model: the foot anatomy is identified via the surface shape instead of distinct landmark points. We propose a 4-segment foot model consisting of the shank (Sha), calcaneus (Cal), metatarsus (Met) and hallux (Hal). These segments are manually selected on a static scan. To track the segments in the dynamic scan, the segments of the static scan are matched on each frame of the dynamic scan using the iterative closest point (ICP) fitting algorithm. Joint rotations are calculated between Sha-Cal, Cal-Met, and Met-Hal. Due to the lower quality scans at heel strike and toe off, the first and last 10% of the stance phase is excluded. The application of the method to 5 healthy subjects, 6 trials each, shows a good repeatability (intra-subject standard deviations between 1° and 2.5°) for Sha-Cal and Cal-Met joints, and inferior results for the Met-Hal joint (>3°). The repeatability seems to be subject-dependent. For the validation, a qualitative comparison with joint kinematics from a corresponding established marker-based multi-segment foot model is made. This shows very consistent patterns of rotation. The ease of subject preparation and also the effective and easy to interpret visual output, make the present technique very attractive for functional analysis of the foot, enhancing usability in clinical practice. PMID:24998032

  4. Reliability of the measures of weight-bearing distribution obtained during quiet stance by digital scales in subjects with and without hemiparesis.

    PubMed

    de Araujo-Barbosa, Paulo Henrique Ferreira; de Menezes, Lidiane Teles; Costa, Abraão Souza; Couto Paz, Clarissa Cardoso Dos Santos; Fachin-Martins, Emerson

    2015-05-01

    Described as an alternative way of assessing weight-bearing asymmetries, the measures obtained from digital scales have been used as an index to classify weight-bearing distribution. This study aimed to describe the intra-test and the test/retest reliability of measures in subjects with and without hemiparesis during quiet stance. The percentage of body weight borne by one limb was calculated for a sample of subjects with hemiparesis and for a control group that was matched by gender and age. A two-way analysis of variance was used to verify the intra-test reliability. This analysis was calculated using the differences between the averages of the measures obtained during single, double or triple trials. The intra-class correlation coefficient (ICC) was utilized and data plotted using the Bland-Altman method. The intra-test analysis showed significant differences, only observed in the hemiparesis group, between the measures obtained by single and triple trials. Excellent and moderate ICC values (0.69-0.84) between test and retest were observed in the hemiparesis group, while for control groups ICC values (0.41-0.74) were classified as moderate, progressing from almost poor for measures obtained by a single trial to almost excellent for those obtained by triple trials. In conclusion, good reliability ranging from moderate to excellent classifications was found for participants with and without hemiparesis. Moreover, an improvement of the repeatability was observed with fewer trials for participants with hemiparesis, and with more trials for participants without hemiparesis. PMID:25541319

  5. 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

  6. The short version of the Activities-specific Balance Confidence (ABC) scale: Its validity, reliability, and relationship to balance impairment and falls in older adults

    PubMed Central

    Schepens, Stacey; Goldberg, Allon; Wallace, Melissa

    2009-01-01

    A shortened version of the ABC 16-item scale (ABC-16), the ABC-6, has been proposed as an alternative balance confidence measure. We investigated whether the ABC-6 is a valid and reliable measure of balance confidence and examined its relationship to balance impairment and falls in older adults. Thirty-five community-dwelling older adults completed the ABC-16, including the six questions of the ABC-6. They also completed the following clinical balance tests: unipedal stance time (UST), functional reach (FR), Timed Up and Go (TUG), and maximum step length (MSL). Participants reported twelve-month falls history. Balance confidence on the ABC-6 was significantly lower than on the ABC-16, however scores were highly correlated. Fallers reported lower balance confidence than non-fallers as measured by the ABC-6 scale, but confidence did not differ between the groups with the ABC-16. The ABC-6 significantly correlated with all balance tests assessed and number of falls. The ABC-16 significantly correlated with all balance tests assessed, but not with number of falls. Test-retest reliability for the ABC-16 and ABC-6 was good to excellent. The ABC-6 is a valid and reliable measure of balance confidence in community-dwelling older adults, and shows stronger relationships to falls than does the ABC-16. The ABC-6 may be a more useful balance confidence assessment tool than the ABC-16. PMID:19615762

  7. 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

  8. The Stance of Stance: A Critical Look at Ways Stance Is Expressed and Modeled in Academic Discourse.

    ERIC Educational Resources Information Center

    Silver, Mark

    2003-01-01

    Raises a number of methodological questions about the universality of commonly applied linguistic categories by offering a critical reading of the adverbial "evidently" as it appears in a corpus of contemporary research articles. Analyzes the adverbial from three general vantage points: its function as hedge or booster; the way it intervenes in…

  9. Herpes genitalis and the philosopher's stance.

    PubMed

    Dunphy, Kilian

    2014-12-01

    For many people, living with genital herpes generates not just episodic physical discomfort but recurrent emotional distress, centred on concerns about how to live and love safely without passing infection to others. This article considers the evidence on herpes transmission, levels of sexual risk, when the law has intervened and to what extent health professionals should advise with respect to these issues. It proposes a mechanism by which moral philosophy might provide a rational basis on which to counsel concerning sexual behaviour. PMID:24429670

  10. Taking a Democratic Stance toward Knowledge

    ERIC Educational Resources Information Center

    Traugh, Cecelia

    2009-01-01

    One of the major priorities that should guide teacher education programs in preparing teachers for their work in a democratic society is to develop a commitment to knowledge that embraces complexity and to place this knowledge into competition with the mainstream vision, which results from a deep reliance on standardized testing and controls much…

  11. Recognizing Stances in Online Debates Swapna Somasundaran

    E-print Network

    Wiebe, Janyce M.

    "which mobile phone is better: iPhone or Blackberry," a participant on the iPhone side may explicitly assert and rationalize why the iPhone is better, and, alternatively, also ar- gue why the Blackberry their opinions, such as "The iPhone is cool," but, more often, they mention associated aspects. Some aspects

  12. Design and control of multimodal single-legged vehicles with variable geometry reaction wheel arrays

    E-print Network

    Schmidt-Wetekam, Christopher

    2011-01-01

    Stance Phase Disturbance Rejection Antisymmetric Actuation [%] LegStance Phase Disturbance Rejection Antisymmetric 0 Actuation [%] LegStance Image Tracking Marker Occlusions Applied Disturbances time [sec] Leg Angle, 2 ? [ deg] Symmetric Actuation [%

  13. 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.

  14. 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 ...

  15. Time of Time

    NASA Astrophysics Data System (ADS)

    Allen Emerson, E.

    In his landmark 1977 paper "The Temporal Logic of Programs", Amir Pnueli gave a fundamental recognition that the ideally nonterminating behavior of ongoing concurrent programs, such as operating systems and protocols, was a vital aspect of program reasoning. As classical approaches to program correctness were based on initial-state/final-state semantics for terminating programs, these approaches were inapplicable to programs where infinite behavior was the norm. To address this shortcoming, Pnueli suggested the use of temporal logic, a formalism for reasoning about change over time originally studied by philosophers, to meaningfully describe and reason about the infinite behavior of programs. This suggestion turned out to be remarkably fruitful. It struck a resonant chord within the formal verification community, and it has had an enormous impact on the development of the area. It matured into an extremely effective mathematical tool for specifying and verifying a vast class of synchronization and coordination problems common in concurrency. Pnueli thus caused a sea-change in the field of program verification, founding the time of reasoning about time, which has been the most successful period in formal methods yet.

  16. 'In good times and in bad': boundary relations of psychoanalysis in post-war USA.

    PubMed

    Brunner, José; Ophir, Orna

    2011-06-01

    This paper suggests writing the history of psychoanalysis by focusing on the manifold ways in which its practitioners may relate to the boundaries dividing it from its neighbouring professions. This approach is illustrated by two loosely interrelated examples: the 1950s debate among leading US psychoanalysts on whether borderline patients can be analysed, and the 1990s responses of psychoanalysts to psychopharmacological treatments of schizophrenia. A close reading of psychoanalysts' journal publications reveals in each instance multiplicity (of voices), instability (of boundaries), duality (of defence and dialogue) and simultaneity (of internal and external addressees). At the same time, a common rhetorical stance emerged in each period, serving as a shared discursive frame while allowing a plurality of boundary relations. PMID:21877388

  17. SYMBOLS FOR TIME = time variable

    E-print Network

    Duchowski, Andrew T.

    SYMBOLS FOR TIME = time variable t = time now, T = target date T* = modeling limit (t=forever) Cost spent to build variation point i at time i = index over variation points #12;SYMBOLS FOR TIME = time variable t = time now, T = target date T* = modeling limit (t=forever) ...adjusted by a factor

  18. 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,

  19. 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…

  20. TIME MANAGEMENT Time Management Questionnaire

    E-print Network

    TIME MANAGEMENT WORKSHOP #12;2 Time Management Questionnaire Self Assessment: Answer "Yes" or "No you tend to complete your assignments on time? 3. ____ Have you estimated how long it takes to read schedule time to study for exams? 8. ____ Do you have a job that requires more than 20 hours a week? 9

  1. Elapsed Time

    NSDL National Science Digital Library

    2007-01-01

    This interactive Java applet allows the user to practice finding elapsed time using analog or digital clocks. Using the "See" mode the user advances a clock from the beginning time to the ending time and the applet calculates the elapsed time. Using the "Guess" mode, the user must calculate the elapsed time between the given beginning and ending times. Three difficulty levels allow the user to practice with hour, five minute, or single minute increments. An optional scoring feature allows the user to keep track of number correct, though this feature is optional.

  2. Thrombin Time

    MedlinePLUS

    ... tests: PT and INR ; PTT ; Reptilase Time ; Fibrinogen ; Coagulation Factors ; D-dimer ; Lupus Anticoagulant Testing At a ... miscarriages, or has unexplained prolonged results on primary coagulation tests such as prothrombin time (PT) or partial ...

  3. 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.

  4. Time lapse

    NSDL National Science Digital Library

    Olivia Worland (Purdue University; Biological Sciences)

    2008-06-16

    Time lapse videos and photography allow us to visualize parts of certain events that we wouldn't normally be able to piece together. Since decay takes time, the causal relationships of this phenomenon can be seen through the use of time lapse videos.

  5. Reaction Time

    NSDL National Science Digital Library

    New York Hall of Science

    1999-01-01

    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.

  6. 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…

  7. 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…

  8. 'Because math': Epistemological stance or defusing social tension in QM?

    E-print Network

    Sohr, Erin Ronayne; Gupta, Ayush; Elby, Andrew

    2015-01-01

    In collaborative small-group work, physics students need to both manage social conflict and grapple with conceptual and epistemological differences. In this paper, we document several outlets that students use as tools for managing social conflict when addressing quantum mechanics tutorials in clinical focus groups. These resources include epistemic distancing, humor, playing on tutorial wording and looking ahead to subsequent questions. We present preliminary analysis of episodes where students work through a Particle in a Box tutorial. Each episode highlights a different manner of navigating social tension: through shared epistemic humor in one case, and reinterpretation of the question in the other.

  9. Conveying a Stance of Religious Pluralism in Children's Literature

    ERIC Educational Resources Information Center

    Sanders, Jennifer; Foyil, Kris; Graff, Jennifer M.

    2010-01-01

    Religious discrimination is a global concern, as social dissonance and devastating violence result from religious intolerance. In order to develop socially competent, global citizens and create a peaceful society, religious diversity must be explored in public school classrooms; yet it remains a controversial and seldom addressed topic. Children's…

  10. 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…

  11. Predicting Stance in Ideological Debate with Rich Linguistic Knowledge

    E-print Network

    Ng, Vincent

    that criminals won't have access to guns if the federal government bans guns? I don't think so. If guns cause will only cause deaths of innocent citizens. Post 2: You said that guns should not be banned. Do you really believe guns can protect citizens from criminals? I don't think so. It is clear that the author of Post 1

  12. Toward an Intercultural Stance: Teaching German and English through Telecollaboration

    Microsoft Academic Search

    PAIGE D. WARE; CLAIRE KRAMSCH

    2005-01-01

    We discuss the challenges of Web-based teaching for language teachers and then describe in detail an extended episode of misunderstanding that occurred between 2 students discussing their versions of history during a classroom-based, asynchronous telecollaborative project be- tween learners of German in the United States and learners of English in Germany. We argue that discussion of such moments of miscommunication

  13. Toward an Intercultural Stance: Teaching German and English through Telecollaboration

    ERIC Educational Resources Information Center

    Ware, Paige D.; Kramsch, Claire

    2005-01-01

    We discuss the challenges of Web-based teaching for language teachers and then describe in detail an extended episode of misunderstanding that occurred between 2 students discussing their versions of history during a classroom-based, asynchronous telecollaborative project between learners of German in the United States and learners of English in…

  14. Ratite Footprints and the Stance and Gait of Mesozoic Theropods

    Microsoft Academic Search

    KEVIN PADIAN; PAUL E. OLSEN

    Footprints of the rhea (Rhea ameriama) are identical in several diagnostic features to tridactyl footprints of the Mesozoic Era attributed to theropod dinosaurs. Of par- ticular interest,'(i) the rhea's feet are placed very close to its body midline as it walks, so that it virtually places one foot in front of the other; (ii) its middle toe (digit III), the

  15. 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.

  16. 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…

  17. 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.

  18. Geologic time

    USGS Publications Warehouse

    Newman, William L.

    2000-01-01

    The Earth is very old 4 1/2 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.

  19. 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.

  20. 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…

  1. 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

  2. Turnover Time

    EPA Science Inventory

    Ecosystems contain energy and materials such as carbon, nitrogen, phosphorus, and water, and are open to their flow-through. Turnover time refers to the amount of time required for replacement by flow-through of the energy or substance of interest contained in the system, and is ...

  3. 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.

  4. Quantum Time

    E-print Network

    Vittorio Giovannetti; Seth Lloyd; Lorenzo Maccone

    2015-06-04

    We give a consistent quantum description of time, based on Page and Wootters' conditional probabilities mechanism, that overcomes the criticisms that were raised against similar previous proposals. In particular we show how the model allows to reproduce the correct statistics of sequential measurements performed on a system at different times.

  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

    OMSI

    2007-01-01

    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. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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- ...

  12. Timing & Time Code Reference REFERENCE GUIDE

    E-print Network

    Berns, Hans-Gerd

    ...........................................................................................................1 Universal Time (UT0....................................................................................................................2 Coordinated Universal TimeTiming & Time Code Reference REFERENCE GUIDE #12;i Time Scales of Measurement Introduction

  13. 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.

  14. accelerates Slow time Fast time

    E-print Network

    of the Earth, but it still remains finite. 4 #12;"INFINITE" speed up! (no limit) infinite gravitational pull on time). Clocks higher in a gravitational well tick faster. 2 #12;Earth GPS general positioning system P

  15. Geologic Time

    NSDL National Science Digital Library

    This Classroom Connectors lesson plan discusses the characteristics of geologic time, including the law of superposition, fossil preservation, casts and molds, and various events through the history of the Earth. The site provides goals, objectives, an outline, time required, materials, activities, and closure ideas for the lesson. The Classroom Connectors address content with an activity approach while incorporating themes necessary to raise the activity to a higher cognition level. The major motivation is to employ instructional strategies that bring the students physically and mentally into touch with the science they are studying.

  16. 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.

  17. Deep Time

    NSDL National Science Digital Library

    WPSU

    2010-05-04

    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.

  18. Time out

    MedlinePLUS

    "Time out" is a technique used by parents and teachers in response to undesired behavior in a child. It involves removing the child from the environment and activities in which the inappropriate behavior occurred, and placing the child in a specific ...

  19. 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

  20. Bilingual Education: An Idea Whose Time Has Come.

    ERIC Educational Resources Information Center

    Shaw, Frederick

    1975-01-01

    Bilingual education is not entirely a new idea. In the 18th and 19th centuries it was practiced in church schools, particularly in German and Spanish. Most communities, however, assumed a strongly assimilationist stance for their public schools, especially after World War I. In recent years, however, this attitude has been partly reversed under…

  1. 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

  2. Pendulum Time

    NSDL National Science Digital Library

    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.

  3. Treatment Time

    Microsoft Academic Search

    C. Chazot; G. Jean

    2008-01-01

    The session duration for hemodialysis (HD) patients has become an old-fashioned issue since the blooming debate on dialysis frequency. However, all over the dialysis community, the most frequent scheme of HD treatment remains three-weekly sessions. Pursuing long dialysis strategy 3 times\\/week for ESRD patients in Tassin after the retirement of the historical leaders relies on the wisdom pillars of dialysis

  4. 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…

  5. Timely toxicology.

    PubMed Central

    Medlin, J F

    1999-01-01

    The ToxChip, a DNA microarray chip, allows the monitoring of the expression levels of thousands of different genes at a time, thereby condensing months of painstaking laboratory tasks into a day's work. For toxicology researchers in particular, this tool is important because it promises a more effective way to identify environmental hazards and their effects on DNA. The ToxChip, developed by NIEHS scientists J. Carl Barrett, Cynthia Afshari, and Emile F. Nuwaysir, could transform the way toxicologists approach environmental problems. PMID:10210703

  6. 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

  7. 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

  8. Yet another time about time

    E-print Network

    Simeonov, Plamen L

    2015-01-01

    This paper presents yet another personal reflection on one the most important concepts in both science and the humanities: time. This elusive notion has been not only bothering philosophers since Plato and Aristotle and goes throughout human history embracing all analytical and creative (anthropocentric) disciplines from mathematics through physical and life sciences to philosophy, psychology, music and art, with a vast body of knowledge across different theories and categories concerning its nature (rational, irrational, arational), appearances/qualia, degrees, dimensions and scales of conceptualization (internal, external, rational, irrational, fractal, discrete, continuous, mechanical, quantum, local, global, etc.), duration ranges, resolutions, modes (present, now, past, future), variety of tenses (e.g. present perfect, present progressive, etc.) and some intuitive, but also fancy phenomenological characteristics such as arrow, stream, texture, width, depth, and perhaps the most distinct one of them, the ...

  9. 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

  10. Acute Orthotic Intervention Does Not Affect Muscular Response Times and Activation Patterns at the Knee

    PubMed Central

    Rose, Holly M.; Shultz, Sandra J.; Arnold, Brent L.; Gansneder, Bruce M.; Perrin, David H.

    2002-01-01

    Objective: To evaluate the short-term effect of a semirigid foot orthotic device on response times and activation patterns of knee musculature in individuals with hyperpronation after a lower extremity perturbation in a single-leg, weight-bearing stance. Design and Setting: We used a lower extremity perturbation device designed to produce a forward and either internal or external rotation of the trunk and femur on the weight-bearing tibia to evoke a reflex response. Subjects were tested both with and without orthotic devices. Subjects: Seventeen (13 male, 4 female) volunteers (age, 20.6 ± 1.8 years; height, 181.0 ± 8.1 cm; weight, 87.4 ± 19.5 kg; navicular drop, 12.1 ± 1.8 mm) with a navicular drop greater than 10 mm volunteered for this study. Measurements: Long latency reflex times were recorded via surface electromyography for the medial and lateral hamstrings, gastrocnemius, and quadriceps muscles. Results: A dependent-sample t test revealed a significant decrease in navicular drop with orthotic intervention (P < .0001). With that confirmed, separate repeated-measures analyses of variance with 2 within factors (orthotic condition and muscle) revealed no significant difference in muscle response time between orthotic and nonorthotic conditions for either internal or external rotation perturbation. Although we found a main effect for muscle for both internal (P < .0001) and external (P < .0001) rotation, indicating a preferred muscle activation order, this activation order did not differ between orthotic and nonorthotic conditions (internal rotation P = .674, external rotation P = .829). Conclusions: Our findings suggest that a short-term application of a semirigid orthotic device does not alter muscle response times or activation patterns of the muscles that stabilize the knee. Further research is needed to determine whether changes in activation patterns may occur over time since mechanical adaptations occur with long-term wear. PMID:12937425

  11. Time Processes for Time Petri-Nets

    Microsoft Academic Search

    Tuomas Aura; Johan Lilius

    1997-01-01

    . Time Petri nets are Petri nets extended with a notion of time,where the occurrence time of a transition is constrained by a static interval.The objective of this work is to give time Petri nets a partial ordersemantics, based on the nonsequential processes semantics for untimednet systems. A time process of a time Petri net is defined as a traditionallyconstructed

  12. 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

  13. 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

  14. Real Time Crises: New Real Time Tensions

    E-print Network

    Mumby, Peter J.

    Real Time Crises: New Real Time Tensions NikGowing Shaping the Future Lecture For ten years Nik 262359 or e.a.hull@exeter.ac.uk Nik Gowing Real Time Crises: New Real Time Tensions Shaping the Future in newsrooms, governments, military commands and corporate organisations in a time of crisis. To reserve your

  15. 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.

  16. 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

  17. GNSS times and UTC

    Microsoft Academic Search

    W. Lewandowski; E. F. Arias

    2011-01-01

    Global Navigation Satellite Systems (GNSSs) use internal reference time scales: GPS Time, GLONASS Time, Galileo System Time and BeiDou System Time. Constructed from a clock ensemble, they are designed for internal system synchronization, necessary to produce a navigation solution. They are usually steered to an external stable reference time scale, for example UTC(USNO), modulo 1 s, for GPS time. To

  18. Quadriceps and Hamstrings Morphology Is Related to Walking Mechanics and Knee Cartilage MRI Relaxation Times in Young Adults

    PubMed Central

    KUMAR, DEEPAK; SUBBURAJ, KARUPPPASAMY; LIN, WILSON; KARAMPINOS, DIMITRIOS C.; MCCULLOCH, CHARLES E.; LI, XIAOJUAN; LINK, THOMAS M.; SOUZA, RICHARD B.; MAJUMDAR, SHARMILA

    2015-01-01

    STUDY DESIGN Controlled laboratory study using a cross-sectional design. OBJECTIVES To analyze the relationship of quadriceps-hamstrings and medial-lateral quadriceps anatomical cross-sectional area (ACSA) ratios with knee loads during walking and articular and meniscal cartilage composition in young, healthy subjects. BACKGROUND Muscle forces affect knee loading during walking, but it is not known if muscle morphology is associated with walking mechanics and cartilage composition in young subjects. METHODS Forty-two knees from 27 young, healthy, active volunteers (age, 20-35 years; body mass index, <28 kg/m2) underwent 3-T magnetic resonance imaging (MRI) and 3-D motion capture. Standard MRI sequences were used for articular and meniscal cartilage T1rho and T2 relaxation times and for quadriceps and hamstrings muscle ACSA. Frontal plane kinetics during the stance phase of walking was calculated. Generalized estimating equation models were used to identify muscle variables that predicted MRI and gait parameters. RESULTS Quadriceps-hamstrings and medial-lateral quadriceps ACSA ratios were positively related to frontal plane loading (? = .27-.54, P?.006), global articular cartilage relaxation times (? = .22-.28, P?.041), and the medial-lateral ratio of meniscus T1rho relaxation time (? = .26-.36, P?.049). The medial-lateral quadriceps ACSA ratio was positively related to global meniscus T1rho relaxation times (? = .30, P = .046). CONCLUSION Higher quadriceps-hamstrings and medial-lateral quadriceps ACSA ratios were associated with higher frontal plane loading during walking and with articular and meniscal cartilage T1rho and T2 relaxation times. These findings highlight the relationships between different knee tissues and knee mechanics in young, healthy individuals. PMID:24175607

  19. 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 ...

  20. 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.

  1. Times of Our Lives.

    ERIC Educational Resources Information Center

    Ramsay, John G.

    2001-01-01

    Lists activities parents can build into their schedules to strengthen their families and help their students succeed, noting the three keys to scheduling during the school year (clarity, discipline, and flexibility). Activities involve: getting ready time, teaching time, friend time, playtime, reading time, down time, adventure time, practice…

  2. Fast Times and Digital Literacy: Participation Roles and Portfolio Construction within Instant Messaging

    ERIC Educational Resources Information Center

    Jacobs, Gloria E.

    2006-01-01

    The purpose of this study was to develop an understanding of adolescent use of instant messaging. Grounded in the New Literacy Studies stance that literacy is a social practice embedded in local contexts and informed by global ideologies (Street, 1995), I argue that participation in digital literacies such as instant messaging has implications for…

  3. Fast Times and Digital Literacy: Participation Roles and Portfolio Construction within Instant Messaging

    Microsoft Academic Search

    Gloria E. Jacobs

    2006-01-01

    The purpose of this study was to develop an understanding of adolescent use of instant messaging. Grounded in the New Literacy Studies stance that literacy is a social practice embedded in local contexts and informed by global ideologies (Street, 1995), I argue that participation in digital literacies such as instant messaging has implications for how wired youth are being prepared

  4. 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

  5. Picosecond time interval measurements

    Microsoft Academic Search

    John B. Rettig; Laszlo Dobos

    1995-01-01

    Efficient measurement techniques have been developed to adequately characterize the performance of a new generation of programmable equivalent time sequential sampling oscilloscopes. These instruments provide time interval measurements with increased repeatability and accuracy. The same characterizations are applicable to more general time interval measurement, and subpicosecond repeatability for rise time measurement of fast step generators (<20 ps rise time) has

  6. Yes IT'S TIME! It's time for spring.

    E-print Network

    New South Wales, University of

    ,500. This Spring issue we dust off the winter cobwebs and hear from COFA students Tom Polo and Sian Mcintyre Cup page 3-4 The LIfe and Times of Tom Polo page 5-6 The Life and Times of Tom Polo page 5-6 GROUP blogger- the time is right for Tom Polo. KD: You are currently a Masters of Fine Art student here at COFA

  7. Personal Time Line

    NSDL National Science Digital Library

    Eric Muller

    2003-01-01

    In this activity, learners work in groups to create a time line representing significant moments in their lives. Learners use scientific suffixes and prefixes to label their time lines, modeling the Geologic Time Line (i.e. Mesozoic, Paleozoic).

  8. 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.

  9. Elapsed Time Two

    NSDL National Science Digital Library

    2007-01-01

    This interactive Java applet allows the user to practice calculating an ending time or a beginning time given the elapsed time using analog or digital clocks. Using the "See" mode the user advances (or rewinds) a clock from the given time using the elapsed time to find the ending (or beginning) time. Using the "Guess" mode, the user must calculate the ending (or beginning) time given the elapsed time. Three difficulty levels allow the user to practice with hour, five minute, or single minute increments. An optional scoring feature allows the user to keep track of number correct.

  10. 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…

  11. Occupational Cohort Time Scales

    PubMed Central

    Roth, H. Daniel

    2015-01-01

    Purpose: This study explores how highly correlated time variables (occupational cohort time scales) contribute to confounding and ambiguity of interpretation. Methods: Occupational cohort time scales were identified and organized through simple equations of three time scales (relational triads) and the connections between these triads (time scale web). The behavior of the time scales was examined when constraints were imposed on variable ranges and interrelationships. Results: Constraints on a time scale in a triad create high correlations between the other two time scales. These correlations combine with the connections between relational triads to produce association paths. High correlation between time scales leads to ambiguity of interpretation. Conclusions: Understanding the properties of occupational cohort time scales, their relational triads, and the time scale web is helpful in understanding the origins of otherwise obscure confounding bias and ambiguity of interpretation. PMID:25647318

  12. 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.

  13. Deep Time: The Geologic Time Scale

    NSDL National Science Digital Library

    2007-01-01

    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.

  14. Synchronized time stamp support

    Microsoft Academic Search

    Kowalkowski

    1994-01-01

    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

  15. Future Coordinated Universal Time

    Microsoft Academic Search

    Dennis D. McCarthy

    2000-01-01

    Coordinated Universal Time (UTC), created by adjusting International Atomic Time (TAI) by the appropriate number of leap seconds, is the uniform time scale that is the basis of most civil timekeeping in the world. The concept of a leap second was introduced to ensure that UTC would not differ by more than 0.9 seconds from UT1, the time determined by

  16. 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…

  17. 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)

  18. 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.

  19. SPACE-TIME--TIME Homer G. Ellis

    E-print Network

    Ellis, Homer

    of an action density for #12;eld equations. A space-time--time geodesic describes a test parti- cle whose rest mass #23; m and electric charge q evolve according to de#12;nite laws. Its motion is governed by four-dimensional Kaluza geometry, with its distinguished Typeset by A M S-T E X 1 #12; 2 HOMER G. ELLIS Killing vector #12

  20. 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.

  1. Ignition timing control

    SciTech Connect

    Lambert, J.E.; Bedross, G.M.

    1993-05-25

    An engine ignition control system for controlling the timing of the spark for initiating burning in the combustion chamber of a four stroke cycle, single cylinder, internal combustion engine is described; said engine having a cylinder, a piston in said cylinder, a crankshaft connected to said piston, said piston being adapted to reciprocate between a top dead center position and a bottom dead center position; a speed sensor means for developing periodic sensor voltage timing pulses, the cycle time between timing pulses being an indication of engine crankshaft speed; means for developing ignition timing pulses, each timing pulse having a leading edge corresponding to a voltage change in a timing voltage pulse and a trailing edge corresponding to an opposite voltage change in a timing voltage pulse; means for developing a spark voltage including an ignition coil and a source of ignition coil current, said spark voltage occurring at a coil primary current interrupt point; means for measuring in real-time, cycle time and a timing pulse time for one engine cycle; and means for computing an optimum delay time from the leading edge of a timing pulse for said one cycle to said interrupt point whereby combustion is initiated at a time in advance of the top dead center position.

  2. GNSS times and UTC

    NASA Astrophysics Data System (ADS)

    Lewandowski, W.; Arias, E. F.

    2011-08-01

    Global Navigation Satellite Systems (GNSSs) use internal reference time scales: GPS Time, GLONASS Time, Galileo System Time and BeiDou System Time. Constructed from a clock ensemble, they are designed for internal system synchronization, necessary to produce a navigation solution. They are usually steered to an external stable reference time scale, for example UTC(USNO), modulo 1 s, for GPS time. To achieve safe operation of a GNSS, a system time should preferably be a uniform time scale not affected by the leap seconds of Coordinated Universal Time (UTC). But this is not compatible with international recommendations that radio broadcast time signals should conform as closely as possible to UTC. This paper describes the various approaches chosen by GNSS providers and the relation between GNSS system times and UTC in terms of numbering of seconds. Different solutions for numbering seconds do not help the GNSS interoperability. This paper also explains why, on some occasions, GNSS system times play a role of alternative time scales with the consequent risk of confusion.

  3. Physiologic time: A hypothesis

    NASA Astrophysics Data System (ADS)

    West, Damien; West, Bruce J.

    2013-06-01

    The scaling of respiratory metabolism with body size in animals is considered by many to be a fundamental law of nature. One apparent consequence of this law is the scaling of physiologic time with body size, implying that physiologic time is separate and distinct from clock time. Physiologic time is manifest in allometry relations for lifespans, cardiac cycles, blood volume circulation, respiratory cycle, along with a number of other physiologic phenomena. Herein we present a theory of physiologic time that explains the allometry relation between time and total body mass averages as entailed by the hypothesis that the fluctuations in the total body mass are described by a scaling probability density.

  4. Screen time and children

    MedlinePLUS

    "Screen time" is a term used for activities done in front of a screen, such as watching TV, working on a computer, or playing video games. Screen time is sedentary activity, meaning you are being physically ...

  5. Media Time Family Pledge

    MedlinePLUS

    ... Listen Español Text Size Email Print Share Media Time Family Pledge Article Body At the beginning and end ... them. Kids learn best with small lessons over time as opposed to one big lecture or sit- ...

  6. Timing system observations

    SciTech Connect

    Winans, J.

    1994-03-01

    The purpose of this document is to augment Synchronized Time Stamp Support authored by Jim Kowalkowski. This document provides additional documentation to clarify and explain software involved in timing operations of the accelerator.

  7. Time in quantum mechanics 

    E-print Network

    Chapin, Kimberly R.

    1997-01-01

    The role of time in quantum mechanics has been and is still very controversial. The purpose of this paper was to explore the historical interpretation of time in quantum mechanics, to determine the current status of this ...

  8. Infinite Time Turing Machines

    Microsoft Academic Search

    Joel David Hamkins

    2002-01-01

    Infinite time Turing machines extend the operation of ordinary Turing machines into transfinite ordinal time. By doing so, they provide a natural model of infinitary computability, a theoretical setting for the analysis of the power and limitations of supertask algorithms.

  9. Clock Time and Entropy

    E-print Network

    Don N. Page

    1993-03-12

    Testable conditional probabilities appear to be restricted to single hypersurfaces (marvelous moments) and depend only on stationary observables. Observable evolution, such as a change of entropy, should be expressed as a dependence upon clock time, not upon inaccessible coordinate time.

  10. 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.

  11. Geologic Time: Online Edition

    NSDL National Science Digital Library

    1997-10-09

    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.

  12. Multiple Time Dimensions

    E-print Network

    Steven Weinstein

    2008-12-19

    The possibility of physics in multiple time dimensions is investigated. Drawing on recent work by Walter Craig and myself, I show that, contrary to conventional wisdom, there is a well-posed initial value problem--deterministic, stable evolution--for theories in multiple time dimensions. Though similar in many ways to ordinary, single-time theories, multi-time theories have some rather intriguing properties which suggest new directions for the understanding of fundamental physics.

  13. Time-reversal mirrors

    Microsoft Academic Search

    M. Fink

    1993-01-01

    Time-reversal of ultrasonic fields allows a very efficient approach to focus pulsed ultrasonic waves through inhomogeneous media. Time-reversal mirrors (TRMS) are made of large transducer arrays, allowing the incident acoustic field to be sampled, time-reversed and re-emitted. The paper introduces the time-reversal approach in a discussion of the techniques used in optics for focusing through inhomogeneous media. The discussion is

  14. Filling the Time

    NSDL National Science Digital Library

    TERC

    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.

  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. Indexing Valid Time Intervals

    Microsoft Academic Search

    Tolga Bozkaya Meral Ozsoyoglu

    1998-01-01

    To support temporal operators and to increase the efficiency of temporal queries,indexing based on temporal attributes is required. We consider the problem of indexing thetemporal dimension in valid time databases. We assume that the temporal information of dataobjects are represented as valid time intervals that have to be managed dynamically by anefficient index structure. Unlike the time intervals in transaction

  17. 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

  18. 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

  19. 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

  20. 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…

  1. 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…

  2. 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

  3. 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.

  4. Astronomical Time Series Analysis

    E-print Network

    Pelt, Jaan

    Astronomical Time Series Analysis Lecture Notes by Jaan Pelt Tartu Observatory Oulu University 23 October - 18 November, 2003 #12;ii #12;Introduction Astronomical time series are somewhat different if to compare with stan- dard time series often used in other branches of science and businesses. The random

  5. Time-reversed acoustics

    Microsoft Academic Search

    Mathias Fink; Didier Cassereau; Arnaud Derode; Claire Prada; Philippe Roux; Mickael Tanter; Jean-Louis Thomas; François Wu

    2000-01-01

    The objective of this paper is to show that time reversal invariance can be exploited in acoustics to create a variety of useful instruments as well as elegant experiments in pure physics. Section 1 is devoted to the description of time reversal cavities and mirrors together with a comparison between time reversal and phase conjugation. To illustrate these concepts, several

  6. Ultrasonic Time Reversal Mirrors

    Microsoft Academic Search

    Mathias Fink; Gabriel Montaldo; Mickael Tanter

    2004-01-01

    For more than ten years, time reversal techniques have been developed in many different fields of applications including detection of defects in solids, underwater acoustics, room acoustics and also ultrasound medical imaging and therapy. The essential property that makes time reversed acoustics possible is that the underlying physical process of wave propagation would be unchanged if time were reversed. In

  7. 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.

  8. The End of Time?

    E-print Network

    J. N. Butterfield

    2001-03-15

    I discuss J. Barbour's Machian theories of dynamics, and his proposal that a Machian perspective enables one to solve the problem of time in quantum geometrodynamics (by saying that there is no time). I concentrate on his recent book 'The End of Time' (1999).

  9. Parametric Timing Analysis

    SciTech Connect

    Vivancos, E; Healy, C; Mueller, F; Whalley, D

    2001-05-09

    Embedded systems often have real-time constraints. Traditional timing analysis statically determines the maximum execution time of a task or a program in a real-time system. These systems typically depend on the worst-case execution time of tasks in order to make static scheduling decisions so that tasks can meet their deadlines. Static determination of worst-case execution times imposes numerous restrictions on real-time programs, which include that the maximum number of iterations of each loop must be known statically. These restrictions can significantly limit the class of programs that would be suitable for a real-time embedded system. This paper describes work-in-progress that uses static timing analysis to aid in making dynamic scheduling decisions. For instance, different algorithms with varying levels of accuracy may be selected based on the algorithm's predicted worst-case execution time and the time allotted for the task. We represent the worst-case execution time of a function or a loop as a formula, where the unknown values affecting the execution time are parameterized. This parametric timing analysis produces formulas that can then be quickly evaluated at run-time so dynamic scheduling decisions can be made with little overhead. Benefits of this work include expanding the class of applications that can be used in a real-time system, improving the accuracy of dynamic scheduling decisions, and more effective utilization of system resources. This paper describes how static timing analysis can be used to aid in making dynamic scheduling decisions. The WCET of a function or a loop is represented as a formula, where the values affecting the execution time are parameterized. Such formulas can then be quickly evaluated at run-time so dynamic scheduling decisions can be made when scheduling a task or choosing algorithms within a task. Benefits of this parametric timing analysis include expanding the class of applications that can be used in a real-time system, improving the accuracy of dynamic scheduling decisions, and more effective utilization of system resources.

  10. Discrete time techniques for time delay estimation

    Microsoft Academic Search

    Giovanni Jacovitti; Gaetano Scarano

    1993-01-01

    Basic aspects of time delay estimation (TDE) based on sampled signals are investigated. The direct cross-correlation method is analyzed and compared to the average square difference function (ASDF) and the (addition only based) average magnitude difference function (AMDF) estimators, Their relative accuracy is theoretically evaluated, and previous empirical results are explained. It is shown that both the ASDF- and the

  11. 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.

  12. New York Times Books

    NSDL National Science Digital Library

    The highlight of this section of the New York Times website (discussed in the January 26, 1996 Scout Report) is the searchable archive of over 50,000 book reviews, author interviews, and book news articles from the newspaper and the New York Times Book Review since 1980. It also contains the full text of the weekly Book Review (available on the web since January 5, 1997) as well as a feature called "Life and Times: Major authors, in their own words and ours," and selected first chapters from New York Times Book Review or New York Times bestseller list books. Note that these sites, while free, require registration.

  13. 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.

  14. SNS TIMING SYSTEM.

    SciTech Connect

    NELSON,J.R.; OERTER,B.; SHEA,T.; SIBLEY,C.

    2001-11-27

    A modern physics facility must synchronize the operation of equipment over a wide area. The primary purpose of the site wide SNS synchronization and timing system is to synchronize the operation of the LINAC, accumulator ring and neutron choppers and to distribute appropriate timing signals to accelerator systems, including the Injector, LINAC, Accumulator Ring and Experimental Facilities. Signals to be distributed include the ring RF clock, real-time timing triggers, machine mode and other informational events. Timing triggers and clocks from the SNS synchronization and timing system are used to synchronize hardware operations including the MEBT beam chopper, RF turn on, synchronous equipment state changes, as well as data acquisition for power supplies and beam diagnostics equipment. This paper will describe the timing equipment being designed for the SNS facility and discuss the tradeoffs between conflicting demands of the accelerator and neutron chopper performance due to AC power grid frequency fluctuations.

  15. 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.

  16. 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.

  17. 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.

  18. 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).

  19. Fuzzy timed Petri nets

    Microsoft Academic Search

    Witold Pedrycz; Heloisa De Arruda Camargo

    2003-01-01

    The study is concerned with a new temporal version of fuzzy Petri nets—fuzzy timed Petri nets (ftPNs). These nets are augmented by temporal fuzzy sets that allow for the representation of timing effect (e.g., aging of information). We show how the time factor can be added as an integral part of the models of transitions and places. The formalism of

  20. Real-time CORBA

    Microsoft Academic Search

    Victor Fay Wolfe; Lisa Cingiser Dipippo; Roman Ginis; Michael Squadrito; Steven Wohlever; Igor Zykh; Russell Johnston

    1997-01-01

    This paper describes the requirements for real-timeextensions to the CORBA standard, which arebeingdeveloped by the Object Management Group's SpecialInterest Group on Real-Time CORBA. The paper alsosurveys e#orts that are developing Real-Time CORBAsystems. It provides a more detailed description of thedynamic Real-Time CORBA system being developedatthe US Navy's NRaD facilities and at the Universityof Rhode Island.1

  1. Making Time for Feedback

    ERIC Educational Resources Information Center

    Fisher, Douglas; Frey, Nancy

    2012-01-01

    Ask any teacher what he or she needs more of, and it is a good bet that time will top the list. Anything that promises to recoup a little bit of their workday time is sure to be a best seller. One overlooked time-saver is in how they use feedback. Teachers know that feedback is important for teaching and learning. Unfortunately, most secondary…

  2. 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.

  3. Intrinsic Time Quantum Geometrodynamics

    E-print Network

    Eyo Eyo Ita III; Chopin Soo; Hoi-Lai Yu

    2015-02-06

    Quantum Geometrodynamics with intrinsic time development and momentric variables is presented. An underlying SU(3) group structure at each spatial point regulates the theory. The intrinsic time behavior of the theory is analyzed, together with its ground state and primordial quantum fluctuations. Cotton-York potential dominates at early times when the universe was small; the ground state naturally resolves Penrose's Weyl Curvature Hypothesis, and thermodynamic and gravitational `arrows of time' point in the same direction. Ricci scalar potential corresponding to Einstein's General Relativity emerges as a zero-point energy contribution. A new set of fundamental commutation relations without Planck's constant emerges from the unification of Gravitation and Quantum Mechanics.

  4. Intrinsic Time Quantum Geometrodynamics

    E-print Network

    Ita, Eyo Eyo; Yu, Hoi-Lai

    2015-01-01

    Quantum Geometrodynamics with intrinsic time development and momentric variables is presented. An underlying SU(3) group structure at each spatial point regulates the theory. The intrinsic time behavior of the theory is analyzed, together with its ground state and primordial quantum fluctuations. Cotton-York potential dominates at early times when the universe was small; the ground state naturally resolves Penrose's Weyl Curvature Hypothesis, and thermodynamic and gravitational `arrows of time' point in the same direction. Ricci scalar potential corresponding to Einstein's General Relativity emerges as a zero-point energy contribution. A new set of fundamental canonical commutation relations without Planck's constant emerges from the unification of Gravitation and Quantum Mechanics.

  5. 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.

  6. Timed multitasking for real-time embedded software

    Microsoft Academic Search

    Jie Liu; E.A. Lee

    2003-01-01

    An event-triggered programming model, timed multitasking, is introduced that also takes a time-centric approach to real-time programming but controls timing properties through deadlines and events rather than time triggers.

  7. Moving methods, travelling times

    Microsoft Academic Search

    Laura Watts; John Urry

    2008-01-01

    Abstract In this paper we examine the relatively new topic of travel time, the ‘valuation’ of which is of great significance in the potential funding,and construction,of infrastructural projects. In the economic appraisals of such projects, which are often of massive scale and impact, itis presumed that such time is wasted, dead or empty, needs no further investigation and should beminimised.

  8. Homemaking Still Takes Time

    ERIC Educational Resources Information Center

    Walker, Lathryn E.

    1969-01-01

    "Families today have many choices about how to use their time and money resources, but, as this study shows, homemaking tasks still demand time despite the many conveniences available. In fact, for women the predicted short work day of the future may still be a distant dream. (Editor)

  9. Commission 31: Time

    Microsoft Academic Search

    Demetrios Matsakis; Pascale Defraigne; M. Hosokawa; S. Leschiutta; G. Petit; Z.-C. Zhai

    2007-01-01

    The most intensely discussed and controversial issue in time keeping has been the proposal before the International Telecommunications Union (ITU) to redefine Coordinated Universal Time (UTC) so as to replace leap seconds by leap hours. Should this proposal be adopted, the practice of inserting leap seconds would cease after a specific date. Should the Earth's rotation continue to de-accelerate at

  10. Survivability Versus Time

    NASA Technical Reports Server (NTRS)

    Joyner, James J., Sr.

    2014-01-01

    Develop Survivability vs Time Model as a decision-evaluation tool to assess various emergency egress methods used at Launch Complex 39B (LC 39B) and in the Vehicle Assembly Building (VAB) on NASAs Kennedy Space Center. For each hazard scenario, develop probability distributions to address statistical uncertainty resulting in survivability plots over time and composite survivability plots encompassing multiple hazard scenarios.

  11. 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…

  12. TTVFast: Transit timing inversion

    NASA Astrophysics Data System (ADS)

    Deck, Katherine; Agol, Eric; Holman, Matt; Nesvorny, David

    2014-04-01

    TTVFast efficiently calculates transit times for n-planet systems and the corresponding radial velocities. The code uses a symplectic integrator with a Keplerian interpolator for the calculation of transit times (Nesvorny et al. 2013); it is available in both C and Fortran.

  13. 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.

  14. 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

  15. On time reversal mirrors

    Microsoft Academic Search

    Albert C. Fannjiang

    2009-01-01

    The concept of time reversal (TR) of a scalar wave is reexamined from basic principles. Five different time-reversal mirrors (TRMs) are introduced and their relations are analyzed. For the boundary behavior, it is shown that for a paraxial wave only the monopole TR scheme satisfies the exact boundary condition while for the spherical wave only the MD-mode TR scheme satisfies

  16. MIMO time reversal communications

    Microsoft Academic Search

    Hee-chun Song; William S. Hodgkiss; William A. Kuperman

    2007-01-01

    A time reversal mirror (TRM) exploits spatial diversity to achieve spatial and temporal focusing, a useful property for communications in an environment with significant multipath. Temporal focusing (pulse compression) mitigates intersymbol interference (ISI) while spatial focusing enables a straightforward extension to multiple- input\\/multiple-output (MIMO) communications. Furthermore, the time reversal process can be combined with adaptive channel equalization to remove the

  17. Time-Varying Gravitomagnetism

    E-print Network

    Bahram Mashhoon

    2008-03-12

    Time-varying gravitomagnetic fields are considered within the linear post-Newtonian approach to general relativity. A simple model is developed in which the gravitomagnetic field of a localized mass-energy current varies linearly with time. The implications of this temporal variation of the source for the precession of test gyroscopes and the motion of null rays are briefly discussed.

  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. 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.

  20. Timing influenced layout design

    Microsoft Academic Search

    Michael Burstein; Mary N. Youssef

    1985-01-01

    We present a new approach to the automatic layout design for VLSI chips which incorporates timing information to influence the placement and wiring processes. This approach is an extension of the hierarchical layout method, in which placement and wiring are performed simultaneously [1]. We add a third phase of timing to the hierarchy, without affecting the computational complexity of the

  1. Postretirement Use of Time

    Microsoft Academic Search

    Marlene M. Rosenkoetter; John M. Gams; Richard A. Engdahl

    2001-01-01

    Retirement is a significant transition in life that creates major changes, especially regarding how a person uses available time. The purpose of this study was to examine the perceptions of all retirees (N = 1,565) from an international company living in seven southeastern states regarding changes in 12 use of time activities following retirement and the implications of those changes

  2. 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.

  3. Time, money, and morality.

    PubMed

    Gino, Francesca; Mogilner, Cassie

    2014-02-01

    Money, a resource that absorbs much daily attention, seems to be involved in much unethical behavior, which suggests that money itself may corrupt. This research examined a way to offset such potentially deleterious effects-by focusing on time, a resource that tends to receive less attention than money but is equally ubiquitous in daily life. Across four experiments, we examined whether shifting focus onto time can salvage individuals' ethicality. We found that implicitly activating the construct of time, rather than money, leads individuals to behave more ethically by cheating less. We further found that priming time reduces cheating by making people reflect on who they are. Implications for the use of time primes in discouraging dishonesty are discussed. PMID:24317421

  4. Self and time.

    PubMed

    Meissner, W W

    2008-01-01

    This article explores the meaning of subjective time and its implications for the understanding of the nature of the self in psychoanalytic terms. Subjective time, the time experience of intrapsychic life, is distinguished from objective time. Its development and evolution in the course of the life cycle are examined, and various aspects of its phenomenology explored. Implications for the understanding of the structure and functioning of the self, especially the combined influence of physiological and environmental processes reflecting the integration of body-mind in the time experience and self-organization are discussed. Some implications for the engagement of the self in the analytic process are suggested, particularly the focusing of therapeutic interaction in the present moment and the implications of the meaning of structural change in reference to the modification of the self-concept through the revision and integration of memory systems in the present interaction between analyst and analysand. PMID:19113962

  5. Physically Variable Compliance in Running Jonathan W. Hurst and Alfred A. Rizzi

    E-print Network

    that is too low results in a long stance time and larger deflection of the leg, possibly reaching compression limitations of the leg. A long stance time is more expensive energetically, because the animal or robot must in the literature that leg compliance plays an important role in running locomotion, our conjecture

  6. 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…

  7. Yes-no questions that convey a critical stance in the language classroom

    Microsoft Academic Search

    Hansun Zhang Waring

    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 interaction. Based on 28 hours of videotaped adult

  8. Keep Your Eyes on the Prize: Critical Stance in the Middle School Classroom

    ERIC Educational Resources Information Center

    Lewison, Mitzi; Heffernan, Lee

    2009-01-01

    This study focuses on ways that sixth graders reacted to the question of book awards and awards in general, positioning themselves as reflective inquirers as they engaged in the regular sixth-grade beginning-of-the-year curriculum--reading books that have been nominated for the state book award. The authors focus on four dispositions of critical…

  9. 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…

  10. Mechanisms underlying center of pressure displacements in obese subjects during quiet stance

    Microsoft Academic Search

    Francesco Menegoni; Elena Tacchini; Matteo Bigoni; Luca Vismara; Lorenzo Priano; Manuela Galli; Paolo Capodaglio

    2011-01-01

    Objective  the aim of this study was to assess whether reduced balance capacity in obese subjects is secondary to altered sensory information.\\u000a \\u000a \\u000a \\u000a Design  cross sectional study.\\u000a \\u000a \\u000a \\u000a Subjects  44 obese (BMI = 40.6 ± 4.6 kg\\/m2 , age = 34.2 ± 10.8 years, body weight: 114,0 ± 16,0 Kg, body height 167,5 ± 9,8 cm) and 20 healthy controls (10 females,\\u000a 10 males, BMI:

  11. Slip-related muscle activation patterns in the stance leg during walking

    Microsoft Academic Search

    April J. Chambers; Rakié Cham

    2007-01-01

    Falls precipitated by slipping are a serious public health concern especially in the elderly. Muscular responses generated during slipping have not been investigated during gait on contaminated floors. This study compared slip-related muscular responses (reactive and proactive) in young and older adults and examined if characteristics of muscular activation patterns during normal gait impact slip severity on contaminated floors. Electromyographic

  12. Emotions in the Cross-Fire: Structuralist vs. Post-Structuralist Stances in Bilingualism Research

    ERIC Educational Resources Information Center

    Kramsch, Claire

    2008-01-01

    What Aneta Pavlenko discusses in this fascinating article is so widely researched, so cogently conceptualized and so richly reflected upon, that one feels like a spoilsport to bring up a debate which the author herself claims to have avoided, namely the "universalist/relativist debate about basic emotions". If I do so in this Commentary, it is not…

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

    E-print Network

    Dollar, Aaron M.

    , contract #W81XWH-11-2-0054, 2. US Army Natick Soldier Research Development and Engineering Center, contract anthropomorphic bipedal robots [1,2], lower-limb wearable exoskeletons [3­6], and biologically- inspired

  14. 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…

  15. Experimental verification of a computational technique for determining ground reactions in human bipedal stance.

    PubMed

    Audu, Musa L; Kirsch, Robert F; Triolo, Ronald J

    2007-01-01

    We have developed a three-dimensional (3D) biomechanical model of human standing that enables us to study the mechanisms of posture and balance simultaneously in various directions in space. Since the two feet are on the ground, the system defines a kinematically closed-chain which has redundancy problems that cannot be resolved using the laws of mechanics alone. We have developed a computational (optimization) technique that avoids the problems with the closed-chain formulation thus giving users of such models the ability to make predictions of joint moments, and potentially, muscle activations using more sophisticated musculoskeletal models. This paper describes the experimental verification of the computational technique that is used to estimate the ground reaction vector acting on an unconstrained foot while the other foot is attached to the ground, thus allowing human bipedal standing to be analyzed as an open-chain system. The computational approach was verified in terms of its ability to predict lower extremity joint moments derived from inverse dynamic simulations performed on data acquired from four able-bodied volunteers standing in various postures on force platforms. Sensitivity analyses performed with model simulations indicated which ground reaction force (GRF) and center of pressure (COP) components were most critical for providing better estimates of the joint moments. Overall, the joint moments predicted by the optimization approach are strongly correlated with the joint moments computed using the experimentally measured GRF and COP (0.78 < or = r(2) < or = 0.99,median,0.96) with a best-fit that was not statistically different from a straight line with unity slope (experimental=computational results) for postures of the four subjects examined. These results indicate that this model-based technique can be relied upon to predict reasonable and consistent estimates of the joint moments using the predicted GRF and COP for most standing postures. PMID:16797023

  16. 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

  17. Developing Inquiry-as-Stance and Repertoires of Practice: Teacher Learning across Two Settings

    ERIC Educational Resources Information Center

    Braaten, Melissa L.

    2011-01-01

    Sixteen science educators joined a science teacher video club for one school year to collaboratively inquire into each other's classroom practice through the use of records of practice including classroom video clips and samples of student work. This group was focused on developing ambitious, equitable science teaching that capitalizes on…

  18. Mutual Stance Building in Dyad of Virtual Agents: Smile Alignment and Synchronisation

    E-print Network

    Pelachaud, Catherine

    process [2]. NVBs actively participate in communicating social attitude, judgment, feeling concerning or the performance of behaviours in response to the other's non-verbal behaviours (e.g., backchannels performed persons engaged in a discussion [7], in developmental psychology, several protocols have stressed

  19. Countering Asocial Justice: Consumer Culture, Stance and a Cartography of Encounter

    ERIC Educational Resources Information Center

    Rhodes, Matthew Dean

    2013-01-01

    In Social Foundations classrooms, social justice approaches to questions of difference are certainly part of the curriculum. After teaching numerous Social Foundations courses, I encountered several issues related to the way rigid identity categories were complemented by neoliberal narratives that seemed to limit class conversation in troubling…

  20. Contribution of Central and Peripheral Vision to the Regulation of Stance: Developmental Aspects.

    ERIC Educational Resources Information Center

    Nougier, Vincent; Bard, Chantal; Fleury, Michelle; Teasdale, Normand

    1998-01-01

    Analyzed postural oscillations in six-, eight-, and 10-year-olds in four visual and two somatosensory conditions. Found that children were more stable with than without vision and more stable with a normal than with an altered support surface. Overall, there was no effect of age. The relative influence of peripheral and central vision on postural…

  1. Journal of Biomechanics 36 (2003) 13271333 Predicting the dynamic postural control response from quiet-stance

    E-print Network

    Collins, James J.

    2003-01-01

    ; Aging; Fluctuation-dissipation theorem; Perturbation 1. Introduction Human postural control during). A statistical mechanics theorem that applies to many stochastic systems is the fluctuation­dissipation theorem of a quietly standing individual, can be characterized as a stochastic process. The fluctuation­dissipation

  2. 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

  3. Postural control in young and elderly adults when stance is perturbed: Dynamics

    Microsoft Academic Search

    Mian-Ju Gu; Albert B. Schultz; Neil T. Shepard; Neil B. Alexander

    1996-01-01

    Responses in maintaining or restoring standing balance were measured in 24 healthy young and 15 healthy elderly adults (mean ages 26 and 72) under four task conditions; two involving self-generated motions and two involving imposed disturbances. The two primary objectives of the study were to quantify the whole-body dynamics of these responses and to identify any age related differences in

  4. The Knowledgeable Parenting Style: Stance Takings and Subject Positions in Media Encounters

    ERIC Educational Resources Information Center

    Aarsand, Liselott

    2014-01-01

    In today's media-saturated societies it can be assumed that encounters with therapists and other experts may have implications for adult learning. Taking the point of departure in the idea of public pedagogy, and by using a close-up analysis of interview talk, the pedagogical agency the media may have on parenting is investigated. Drawing…

  5. Non-classical computation and the computationalist stance towards the nat-ural and cognitive sciences

    E-print Network

    Kent, University of

    computational substrate. This paradigm is grounded in two main assumptions: the functionalist paradigm, which of mind. Whilst much study and criticism has been made of the functionalist assumptions that underly

  6. Preservice Teachers Listen to Families of Students with Disabilities and Learn a Disability Studies Stance

    ERIC Educational Resources Information Center

    Sauer, Janet S.; Kasa, Christi

    2012-01-01

    "These families must be so sad. I just wonder what they do and if they have any type of normal life." "I am not sure how I will work with parents. I think they probably look to the school for a lot of help." These quotes were taken from preservice teachers' papers early in their teacher education program, in which they were asked to describe what…

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

    Microsoft Academic Search

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

    2009-01-01

    Even though there is a high degree of scientific uncertainty about the risks of nanotechnology, many scholars have argued\\u000a 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

  8. "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…

  9. 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

  10. 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…

  11. 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…

  12. Playing the Paramecium: Science Education from the Stance of the Cultural Studies of Science

    Microsoft Academic Search

    Matthew Weinstein

    1998-01-01

    The recently released National Science Education Standards claim that science is a social process, although that axiom is marginalized in the Standards' overall vision of a restructured science education. This article explores how science education might be shaped if that claim and one body of research that supports it, the cultural studies of science, were taken as a basis for

  13. November 16, 2010 Rep.-Elect West's Drilling Stance --and Refusal to Back Down --

    E-print Network

    Belogay, Eugene A.

    that we must invest in oil, natural gas, clean coal, nuclear, hydrogen, cost-effective bio-fuels, wind, and environmental accidents like the one off the Gulf Coast." West responded without the flinch Democrats might have the optimal mix of U.S. fuel sources to a "diversified investment portfolio" on his campaign website. "Now

  14. 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…

  15. Taking an Investigative Stance in Using the Professional Standards in the Languages Classroom

    ERIC Educational Resources Information Center

    Farmer, Kylie

    2009-01-01

    The Professional Standards Project (PSP) is a nationally coordinated professional learning program for languages teachers, to improve the quality of languages teaching and, thereby, improve student learning. It is based on the use of the "Professional standards for accomplished teaching of languages and cultures" (hereafter, "the Standards") as a…

  16. Enforced symmetry of the stance phase for the Spring-Loaded Inverted Pendulum

    Microsoft Academic Search

    Giulia Piovan; Katie Byl

    2012-01-01

    The Spring-Loaded Inverted Pendulum (SLIP) is considered the simplest model to effectively describe bouncing gaits (such as running and hopping) for many legged animals and robots. For this reason, it is has often been used as a model for robot design. A key challenge in using this model, however, is the lack of a closed-form solution for the equations of

  17. Geometric Characterization and Experimental Validation of Frictional 3Contact Equilibrium Stances in Three-Dimensions

    Microsoft Academic Search

    Elon Rimon

    2007-01-01

    Quasistatic multi-legged locomotion consists of a sequence of equilibrium postures where the mechanism supports itself against gravity while moving free limbs to new positions. A posture maintains equilibrium if the contacts can passively support the mechanism against gravity. This paper is concerned with computation and graphical characterization of equilibrium postures for mechanisms supported by frictional contacts in a three-dimensional gravitational

  18. Computing 3-legged Equilibrium Stances in Three-dimensional Gravitational Environments

    Microsoft Academic Search

    Or Yizhar; Elon Rimon

    2006-01-01

    Quasistatic multi-legged locomotion consists of a sequence of equilibrium postures where the mechanism supports itself against gravity while moving free limbs to new positions. A posture maintains equilibrium if the contacts can passively support the mechanism against gravity. This paper is concerned with identifying and computing equilibrium postures for mechanisms supported by frictional contacts in a three-dimensional gravitational field. The

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

    E-print Network

    , a common movement abnormality among individuals with stroke and cerebral palsy, is often associated or cerebral palsy [1]. The exaggerated ankle plantarflexion at initial foot contact typical of equinus gait

  20. Creating a Contrastive Rhetorical Stance: Investigating the Strategy of Problematization in Students' Argumentation

    ERIC Educational Resources Information Center

    Mei, Wu Siew

    2006-01-01

    It is often the case that undergraduates writing essays to fulfil course requirements have an academic audience (i.e. lecturer/s marking the essay) as their target readers. These texts may represent a form of academic writing by novice writers in the process of learning academic discourse and conventions. Though these texts may not be comparable…

  1. 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…

  2. J's Epistemological Stance and Strategies To appear in Intentional Conceptual Change, G. Sinatra &

    E-print Network

    Elby, Andy

    & P. Pintrich (Eds.), Lawrence Erlbaum Associates Andrea A. diSessa Graduate School of Education increasingly active in recent years; see Hofer and Pintrich's (1997) review article. In general, this research and Pintrich, 1997) still may presume coherent belief-like attributions (most obviously at poles

  3. Agreement on abortion unravels. Vatican criticized for tough stance at U.N. conference.

    PubMed

    1994-09-01

    The International Conference on Population and Development, underway in Cairo, has been dominated by acrimonious debate on the issue of abortion. By the third day of the conference, agreement had been reached by 90% of the proposed Program of Action. Delegates appeared to have developed a compromise passage that urged governments to recognize illegal abortion as a major public health problem. However, hours after the compromise, delegations from Argentina, Ecuador, Guatemala, Honduras, Malta, Slovakia, Uruguay, and Guam--all of which have Roman Catholic majorities--withdrew their support, claiming that some phrases were pro-abortion. Many conference participants are concerned that the Vatican and its Muslim allies are forcing the issue of women's lives and health to become subordinated to a male-dominated political struggle. PMID:12288303

  4. Humanity's first healers: psychological and psychiatric stances on shamans and shamanism

    Microsoft Academic Search

    STANLEY KRIPPNER

    Background: the author describes shamans as practitioners who deliberately shift their phenomenological pattern of attention, perception, cognition, and awareness in order to obtain information not ordinarily available to members of the social group that granted them privileged status. Objectives: to describe how these phenomenological shifts were accomplished and used. Methods: archival studies of shamanic literature as well as field research

  5. 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

  6. Maintenance of upright stance in humans in normal and virtual visual environments

    Microsoft Academic Search

    B. N. Smetanin

    2007-01-01

    We recorded in 16 healthy subjects the sagittal and frontal components of the stabilogram when standing on a rigid motionless\\u000a or movable (oscillating) platform under four conditions of visual control: (i) open eyes, OE; (ii) closed eyes, CE; (iii)\\u000a central vision, CV, and (iv) virtual visual environment, VVE. Under the latter condition, subjects observed the 3D image of\\u000a a room,

  7. Digital time delay

    DOEpatents

    Martin, A.D.

    1986-05-09

    Method and apparatus are provided for generating an output pulse following a trigger pulse at a time delay interval preset with a resolution which is high relative to a low resolution available from supplied clock pulses. A first lumped constant delay provides a first output signal at predetermined interpolation intervals corresponding to the desired high resolution time interval. Latching circuits latch the high resolution data to form a first synchronizing data set. A selected time interval has been preset to internal counters and corrected for circuit propagation delay times having the same order of magnitude as the desired high resolution. Internal system clock pulses count down the counters to generate an internal pulse delayed by an internal which is functionally related to the preset time interval. A second LCD corrects the internal signal with the high resolution time delay. A second internal pulse is then applied to a third LCD to generate a second set of synchronizing data which is complementary with the first set of synchronizing data for presentation to logic circuits. The logic circuits further delay the internal output signal with the internal pulses. The final delayed output signal thereafter enables the output pulse generator to produce the desired output pulse at the preset time delay interval following input of the trigger pulse.

  8. Ultrasonic Time Reversal Mirrors

    NASA Astrophysics Data System (ADS)

    Fink, Mathias; Montaldo, Gabriel; Tanter, Mickael

    2004-11-01

    For more than ten years, time reversal techniques have been developed in many different fields of applications including detection of defects in solids, underwater acoustics, room acoustics and also ultrasound medical imaging and therapy. The essential property that makes time reversed acoustics possible is that the underlying physical process of wave propagation would be unchanged if time were reversed. In a non dissipative medium, the equations governing the waves guarantee that for every burst of sound that diverges from a source there exists in theory a set of waves that would precisely retrace the path of the sound back to the source. If the source is pointlike, this allows focusing back on the source whatever the medium complexity. For this reason, time reversal represents a very powerful adaptive focusing technique for complex media. The generation of this reconverging wave can be achieved by using Time Reversal Mirrors (TRM). It is made of arrays of ultrasonic reversible piezoelectric transducers that can record the wavefield coming from the sources and send back its time-reversed version in the medium. It relies on the use of fully programmable multi-channel electronics. In this paper we present some applications of iterative time reversal mirrors to target detection in medical applications.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. Pulsar Timing Arrays

    NASA Astrophysics Data System (ADS)

    Lynch, Ryan S.

    2015-05-01

    Pulsars, and especially millisecond pulsars, can be used as precision clocks to explore a wide range of phenomena. An array of millisecond pulsars distributed across the sky can be used to detect low-frequency gravitational waves by searching for a correlated signature between pulsars, arising from the influence of gravitational waves at the Earth. These pulsar timing arrays complement other methods of gravitational wave detection in their frequency coverage and the physics they probe. I will introduce the basics of pulsar timing and discuss how it applies to the detection and study of the gravitational wave Universe. Pulsar timing array collaborations, current results, and future prospects will also be presented.

  18. GSA Geologic Time Scale

    NSDL National Science Digital Library

    1999-01-01

    This Geological Society of America (GSA) site contains a detailed geologic time scale as an educational resource. It may be downloaded to a larger size, and includes all Eras, Eons, Periods, Epochs and ages as well as magnetic polarity information.

  19. Fathering: The First Time.

    ERIC Educational Resources Information Center

    Klein, Bruce

    1985-01-01

    Describes a group called "Fathering: The First Time" formed to help new fathers cope with stress and to share support and information. Discusses the therapists' role and group process from euphoria to competency. (JAC)

  20. 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.

  1. 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 ...

  2. 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 ...

  3. 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.

  4. 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

  5. Introduction NCP time flux

    E-print Network

    Wirosoetisno, Djoko

    of freak waves in wave tanks with wave-makers [used for testing model offshore structures] wave-sloshing- Autonomous Systems NCP time flux Spatial NCP? Conclusion Hele-Shaw Wave Tank Simulation of damped, sloshing

  6. 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 ...

  7. Time consistent portfolio management

    E-print Network

    Ekeland, Ivar; Pirvu, Traian A

    2010-01-01

    This paper considers the portfolio management problem of optimal investment, consumption and life insurance. We are concerned with time inconsistency of optimal strategies. Natural assumptions, like different discount rates for consumption and life insurance, or a time varying aggregation rate lead to time inconsistency. As a consequence, the optimal strategies are not implementable. We focus on hyperbolic discounting, which has received much attention lately, especially in the area of behavioural finance. Following [10], we consider the resulting problem as a leader-follower game between successive selves, each of whom can commit for an infinitesimally small amount of time. We then define policies as subgame perfect equilibrium strategies. Policies are characterized by an integral equation which is shown to have a solution. Although we work on CRRA preference paradigm, our results can be extended for more general preferences as long as the equations admit solutions. Numerical simulations reveal that for the ...

  8. 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.

  9. A Mesozoic time scale

    Microsoft Academic Search

    Felix M. Gradstein; Frits P. Agterberg; James G. Ogg; Jan Hardenbol; Paul van Veen; Jacques Thierry; Zehui Huang

    1994-01-01

    We present an integrated geomagnetic polarity and stratigraphic time scale for the Triassic, Jurassic, and Cretaceous periods of the Mesozoic Era, with age estimates and uncertainty limits for stage boundaries. The time scale uses a suite of 324 radiometric dates, including high-resolution Ar-40\\/Ar-39 age estimates. This framework involves the observed ties between (1) radiometric dates, biozones, and stage boundaries, and

  10. Pulsar timing array projects

    NASA Astrophysics Data System (ADS)

    Hobbs, G.

    2010-01-01

    Pulsars are amongst the most stable rotators known in the Universe. Over many years some millisecond pulsars rival the stability of atomic clocks. Comparing observations of many such stable pulsars may allow the first direct detection of gravitational waves, improve the Solar System planetary ephemeris and provide a means to study irregularities in terrestrial time scales. Here we review the goals and status of current and future pulsar timing array projects.

  11. On time reversal mirrors

    Microsoft Academic Search

    Albert C. Fannjiang

    2009-01-01

    The concept of time reversal (TR) of scalar wave is reexamined from basic\\u000aprinciples. Five different time reversal mirrors (TRM) are introduced and their\\u000arelations are analyzed. For the boundary behavior, it is shown that for\\u000aparaxial wave only the monopole TR scheme satisfies the exact boundary\\u000acondition while for spherical wave only one of the mixed mode TR scheme,

  12. Comprehending Geologic Time

    NSDL National Science Digital Library

    You can use this calculator to create your own metaphor for geologic time. The history of the could be the the distance from your home to school - you can figure out where dinosaurs would be on the trip. Or the history of time could be the length of a class - and you could figure how much of the class you have to sit through before intelligence appears.

  13. TechKnow Times

    NSDL National Science Digital Library

    TechKnow Times(tm) specializes in selecting and synthesizing information about Internet resources. Its goal is to make information access as simple and as quick as possible. It covers news related to Internet and online marketing, World Wide Web sites and design, and online technology and culture, all drawn from a wide range of print and electronic sources. TechKnow Times(tm) is giving online entrepreneurs the information they need to accomplish their goals.

  14. 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

  15. Time in quantum mechanics

    E-print Network

    Chapin, Kimberly R.

    1997-01-01

    to describe the quantum mechanical system The first, matrix mechanics, was presented by Heisenberg [31-33] in 1925. The second, wave mechanics, was presented by Schrodinger [34-37] a year later. In 1926, Schrodmger [38] demonstrated the equivalence... can jump &om one state to another. The result is a discontinuous variation in time (i. e. the tune atom) [42]. Throughout the development of quantum mechanics, this atomistic view of time surfaces again and again, For example, In 1925, J. J...

  16. Interactive Geological Time Scale

    NSDL National Science Digital Library

    This time scale allows students to select multiple time periods from a list and view them on a highlighted display. It shows the relationship between eon, era, period, sub-period, and epoch and also includes the date in mega-annum (Ma) or millions of years before present. The scale reflects the changes in the Cenozoic Era (Tertiary and Quaternary have been eliminated and the Neogene modified) in the most recent International Stratigraphic Charts.

  17. Fossils, rocks, and time

    USGS Publications Warehouse

    Edwards, Lucy E.; Pojeta, John, Jr.

    1993-01-01

    We study out Earth for many reasons: to find water to drink or oil to run our cars or coal to heat our homes, to know where to expect earthquakes or landslides or floods, and to try to understand our natural surroundings. Earth is constantly changing--nothing on its surface is truly permanent. Rocks that are not on top of a mountain may once have been on the bottom of the sea. Thus, to understand the world we live on, we must add the dimension of time. We must study Earth's history. When we talk about recorded history, time is measured in years, centuries, and tens of centuries. When we talk about Earth history, time is measured in millions and billions of years. Time is an everyday part of our lives. We keep track of time with a marvelous invention, the calendar, which is based on the movements of the Earth in space. One spin of Earth on its axis is a day, and one trip around the sun is a year. The modern calendar is a great achievement, developed over many thousands of years as theory and technology improved. People who study Earth's history also use a type of calendar, called the geologic time scale. It looks very different from the familiar calendar. In some ways, it is more like a book, and the rocks are its pages. Some of the pages are torn or missing, and the pages are not numbered, but geology gives us the tools to help us read this book.

  18. 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

  19. 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

  20. Synchronizing Time Servers Leslie Lamport

    E-print Network

    Rajamani, Sriram K.

    . For telling time, the time provided by each server should be a close approx- imation to Universal Time (the . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 3 Obtaining Universal Time 9 4 Providing The Service Time 11 4.1 Ideal Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 4.2 Synchronization and Time-Correctness of Ideal Clocks . . . . 17 4.3 Broadcasting Universal

  1. Synchronizing Time Servers Leslie Lamport

    E-print Network

    Lamport ,Leslie

    . For telling time, the time provided by each server should be a close approx­ imation to Universal Time (the . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 3 Obtaining Universal Time 9 4 Providing The Service Time 11 4.1 Ideal Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 4.2 Synchronization and Time­Correctness of Ideal Clocks . . . . 17 4.3 Broadcasting Universal

  2. 49 CFR 234.265 - Timing relays and timing devices.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...CROSSING SIGNAL SYSTEM SAFETY AND STATE ACTION PLANS Maintenance, Inspection, and Testing Inspections and Tests § 234.265 Timing relays and timing...predetermined time interval shall be shown on the plans or marked on the timing relay or...

  3. Time-domain imaging

    NASA Technical Reports Server (NTRS)

    Tolliver, C. L.

    1989-01-01

    The quest for the highest resolution microwave imaging and principle of time-domain imaging has been the primary motivation for recent developments in time-domain techniques. With the present technology, fast time varying signals can now be measured and recorded both in magnitude and in-phase. It has also enhanced our ability to extract relevant details concerning the scattering object. In the past, the interface of object geometry or shape for scattered signals has received substantial attention in radar technology. Various scattering theories were proposed to develop analytical solutions to this problem. Furthermore, the random inversion, frequency swept holography, and the synthetic radar imaging, have two things in common: (1) the physical optic far-field approximation, and (2) the utilization of channels as an extra physical dimension, were also advanced. Despite the inherent vectorial nature of electromagnetic waves, these scalar treatments have brought forth some promising results in practice with notable examples in subsurface and structure sounding. The development of time-domain techniques are studied through the theoretical aspects as well as experimental verification. The use of time-domain imaging for space robotic vision applications has been suggested.

  4. 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

  5. Timed-Arc Petri Nets vs. Networks of Timed Automata

    E-print Network

    Srba, Jiri

    Timed-Arc Petri Nets vs. Networks of Timed Automata Jir´i Srba BRICS Department of Computer Science mutual translations between the classes of 1- safe timed-arc Petri nets (and its extension with testing (polynomial time) reductions between networks of timed automata and 1-safe timed-arc Petri nets preserving

  6. 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

  7. Translating Real-Time UML Timing Constraints into Real-Time Logic Formulas

    E-print Network

    Cheng, Albert M. K.

    Translating Real-Time UML Timing Constraints into Real-Time Logic Formulas Gowri Aruchamy and Albert Mo Kim Cheng Real-Time Systems Laboratory Department of Computer Science University of Houston Modeling, Real-Time Systems, Timing Constraints, Verification, RTL Abstract Real-time software development

  8. Reality of Time

    E-print Network

    S. C. Tiwari

    2001-10-08

    The meaning of instantaneous action at a distance is elucidated. It is shown that the absence of a medium to transmit action (usually referred to as AAD in the literature) and instantaneous action are not identical. Since the term "instantaneous" is incompatible with relativity and field theory, a critique is presented on the concept of time in relativity. It is argued that relativity does not deal with the nature of time. Physical reality of the absolute time is envisaged, and instantaneous action is proposed to be a natural consequence of it. Possibly gravity is such kind of a force, however the electromagnetic force, though envisaged as direct particle interaction (i.e. without intermediary fields) can not be instantaneous.

  9. 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.

  10. Reading Time Series Plots

    NSDL National Science Digital Library

    Shelley Olds

    This activity provides a brief introduction to GPS and provides a student activity to practice creating and reading time series plots with simplified GPS data. Students graph how a tectonic plate (and the GPS unit attached to it) has moved over a five year time period by moving a GPS model across a North-East coordinate graph. Students practice these skills by analyzing GPS time series from two GPS stations in Iceland. Teaching Tips Adaptations that allow this activity to be successful in an online environment Need to really transform to an online environment. I did have one participant draw the vectors on an online map of Iceland - however, only one person gets to do this, so I'd like to figure out other techniques for this. Elements of this activity that are most effective Recommendations for other faculty adapting this activity to their own course:

  11. Constructing Time Machines

    E-print Network

    G. M. Shore

    2002-10-15

    The existence of time machines, understood as spacetime constructions exhibiting physically realised closed timelike curves (CTCs), would raise fundamental problems with causality and challenge our current understanding of classical and quantum theories of gravity. In this paper, we investigate three proposals for time machines which share some common features: cosmic strings in relative motion, where the conical spacetime appears to allow CTCs; colliding gravitational shock waves, which in Aichelburg-Sexl coordinates imply discontinuous geodesics; and the superluminal propagation of light in gravitational radiation metrics in a modified electrodynamics featuring violations of the strong equivalence principle. While we show that ultimately none of these constructions creates a working time machine, their study illustrates the subtle levels at which causal self-consistency imposes itself, and we consider what intuition can be drawn from these examples for future theories.

  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. Activated clotting time (ACT).

    PubMed

    Horton, Stephen; Augustin, Simon

    2013-01-01

    The standard assay for monitoring anticoagulation during extracorporeal life support (ECLS) is the activated clotting time (ACT) test, with celite, kaolin, and glass beads being the most commonly used activators to initiate contact activation. The point-of-care ACT test has been the preferred test in catheterization labs and cardiac theatres because it has a number of advantages over laboratory tests (Spinler et al., Ann Pharmacother 39(7-8):1275-1285, 2005): Shorter time between sampling and results. Smaller blood sample size. Availability to have test performed by non-lab personnel. Reduced errors associated with sample mislabeling/mishandling. Decreased risk of sample degradation with time. There are other coagulation monitoring tests available; however these are usually specific and do not take into account the global picture of the entire clotting system. The standard coagulation tests (prothrombin time (PT), activated partial thromboplastin time, thrombin time (TT), and fibrinogen level) are plasma tests measuring plasma haemostasis and not patient haemostasis. The ACT measurement uses whole blood, thereby incorporating the importance of platelets and phospholipids in the role of coagulation. Many of the problems with the haemostatic system during ECLS are caused by the activation of platelets, which are not detected by standard tests. Because an ACT test is nonspecific there are many variables such as hypothermia, platelets, aprotinin, GP IIb/IIIa antagonists, haemodilution, etc. that can alter its results. For this reason it is important to gain an understanding as to how these variables interact for meaningful interpretation of the ACT test result. PMID:23546712

  15. Time and production systems

    SciTech Connect

    Salter, R.M.

    1981-12-01

    The utility of rule based production systems seems to be in the ability to model domains consisting of independent states and actions, in which process interaction is minimal. This methodology is suitable for domains outside of the realm of human information processing, in particular, in representing domains of continuous processes. We apply it to the design of a world modeling system, where objects and relationships are observed over time. We consider the effects of embedding time into a rule based system, where individual productions represent instantaneous events which are grouped together to form processes. We illustrate by discussing a particular implementation, the language CONCUR.

  16. 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.

  17. 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.

  18. Sky Time: Kinesthetic Astronomy

    NSDL National Science Digital Library

    Dr. Cherilynn A. Morrow

    2004-01-01

    Through a series of simple body movements, learners gain insight into the relationship between time and astronomical motions of Earth (rotation about its axis, and orbit around the Sun), and also about how these motions influence what we see in the sky at various times of the day and year. This activity can be used to introduce seasons on Earth and other planets. Learners will especially enjoy finding their birthdays in the orbit and using a zodiac diagram. This comprehensive lesson plan includes detailed background information, common misconceptions, extensions, teacher tips, references/resources, and FAQs.

  19. Quantum time machine

    E-print Network

    Pedro F. Gonzalez-Diaz

    1997-12-06

    The continuation of Misner space into the Euclidean region is seen to imply the topological restriction that the period of the closed spatial direction becomes time-dependent. This restriction results in a modified Lorentzian Misner space in which the renormalized stress-energy tensor for quantized complex massless scalar fields becomes regular everywhere, even on the chronology horizon. A quantum-mechanically stable time machine with just the sub-microscopic size may then be constructed out of the modified Misner space, for which the semiclassical Hawking's chronology protection conjecture is no longer an obstruction.

  20. Epistemology in Cyclic Time

    E-print Network

    Moninder Singh Modgil

    2005-01-30

    Consider the scenario, in which human civilization undergoes periodic eras of progression and regression, and consequently, changes in cosmological knowledge are cyclic. There exist solutions of general theory of relativity, such as the G\\"{o}del universe, in which the cosmos is rotating. If the real universe is indeed rotating, than this would be a reversion to rotating universe models, used in ancient cosmological models. We argue that such reversions in physical models would be inevitable in a space-time in which time is having $S^1$ (circular) topology.

  1. 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

  2. TIMED Solar EUV experiment

    Microsoft Academic Search

    Thomas N. Woods; Scott Bailey; Frank Eparvier; George Lawrence; Judith Lean; Bill McClintock; Raymond Roble; Gary J. Rottman; Stanley C. Solomon; W. Kent Tobiska

    2000-01-01

    The Solar EUV Experiment (SEE) selected for the NASA Thermosphere, Ionosphere, and Mesosphere Energetics and Dynamics (TIMED) mission will measure the solar vacuum ultraviolet (VUV) spectral irradiance from 0.1 to 200 nm. To cover this wide spectral range two different types of instruments are used: a grating spectrograph for spectra above 25 nm and a set of silicon soft x-ray

  3. Time domain circuit analysis

    Microsoft Academic Search

    O. W. Andersen

    1992-01-01

    The program Power Electronic Circuit Analysis (PECAN), which has been made to handle some power engineering applications not suited for SPICE or EMTP, is discussed. Time functions of voltages, currents, torque, angular speed, power, and other derived quantities can be calculated and plotted on the screen a printer, or a plotter. The calculations are performed stepwise for a series of

  4. Time Dependent Fluids

    ERIC Educational Resources Information Center

    Collyer, A. A.

    1974-01-01

    Discusses the flow characteristics of thixotropic and negative thixotropic fluids; various theories underlying the thixotropic behavior; and thixotropic phenomena exhibited in drilling muds, commercial paints, pastes, and greases. Inconsistencies in the terminology used to label time dependent effects are revealed. (CC)

  5. Time Synchronization In Spline

    Microsoft Academic Search

    Richard C. Waters

    The Spline scalable platform for interactive environments makes it easy to build virtual worlds where multiple people interact with each other and with computer simulations in a 3D visual and audio environment. A key problem shared by Spline and many other systems is achieving accurate time synchronization of events and data streams. In Spline, synchronization is achieved through the use

  6. Probing times [Microwave Bytes

    Microsoft Academic Search

    Steve Cripps

    2009-01-01

    I frequently get asked whether I find myself running out of things to write about in this column. It's a very simple question to answer, yes I do. When I started writing Microwave Bytes over two years ago, it seemed that by the time I finished one submission, usually sometime late on the deadline date (fortunately extended by my European

  7. Geologic time scale bookmark

    USGS Publications Warehouse

    U.S. Geological Survey

    2012-01-01

    This bookmark, designed for use with U.S. Geological Survey activities at the 2nd USA Science and Engineering Festival (April 26–29, 2012), is adapted from the more detailed Fact Sheet 2010–3059 "Divisions of Geologic Time." The information that it presents is widely sought by educators and students.

  8. 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.…

  9. 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.

  10. Timed Petri net schedules

    Microsoft Academic Search

    J. Carlier; Philippe Chrétienne

    1987-01-01

    In this paper, we define Timed Petri Net schedules and study some of their properties. We prove that the set of schedules issued from a firable sequence of the underlying Petri net has a minimum element we call earliest schedule of the sequence. We then propose a polynomial algorithm to compute it. In order to study earliest schedules, we introduce

  11. Ignition timing control

    Microsoft Academic Search

    J. E. Lambert; G. M. Bedross

    1993-01-01

    An engine ignition control system for controlling the timing of the spark for initiating burning in the combustion chamber of a four stroke cycle, single cylinder, internal combustion engine is described; said engine having a cylinder, a piston in said cylinder, a crankshaft connected to said piston, said piston being adapted to reciprocate between a top dead center position and

  12. Time, history and revolution

    Microsoft Academic Search

    Ulysses Santamaria; J. Anglin; MARXIST TRADITION

    1986-01-01

    To paraphrase the Ninth Thesis on Feuerbach, one could say that, as opposed to speculative materialism, dialectical materialism conceives the time of social development as a practical activity, and not as a factor that can be taken in isolation, a neutral parameter of development. Regis Debray [1

  13. 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…

  14. Time in perspective.

    PubMed

    Gorea, Andrei; Hau, Janice

    2013-08-01

    Perceptions of time and space are subject to strong contextual effects. Like their physical counterparts, they appear to be bound together. The perceived spatial extent of a constant retinal extent increases with its perceived distance from the observer. The perceived duration of a moving object increases with its covered angular trajectory. It follows that the perceived duration of moving objects covering identical angular trajectories should also increase with distance. Using three-dimensionally rendered balls rolling for 600 ms, 900 ms, and 1,200 ms and covering 5.5°, 11°, and 22° trajectories in fronto-parallel planes of a linear-perspective scene, we showed that perceived duration dilates by up to 50% as the fronto-parallel plane of the rolling ball recedes from the observer. Such time dilation is mostly contributed to by the smaller size of the distant ball. As in a three-dimensional world, objects' sizes and their covered trajectories per time unit decrease with distance, and as the two factors lead to opposite perceived-duration effects, the results suggest a form of time constancy in a three-dimensional world. PMID:23774463

  15. Time [year] -normalized

    E-print Network

    Seehafer, Norbert

    Time [year] -normalized Southern Oscillation Index 1880 1900 1920 1940 1960 1980 2000 -4 -2 0 2 4 and increases during the La Niña phase. The ENSO is mostly characterized by an index called Southern Oscillation-precipi- tation (red colour intensity of varved lake sediments EP160) and Southern Oscillation Index we have found

  16. Graduate Time Study. 1992.

    ERIC Educational Resources Information Center

    Harrisburg Area Community Coll., PA. Office of Institutional Research.

    To determine the average time students take to complete an associate degree, certificate, or diploma, Harrisburg Area Community College (HACC), in Pennsylvania, conducted a study of all 944 students who graduated during the 1991-92 academic year. Data for the sample were gathered related to age, sex, grade point average, academic major, attendance…

  17. Video time encoding machines.

    PubMed

    Lazar, Aurel A; Pnevmatikakis, Eftychios A

    2011-03-01

    We investigate architectures for time encoding and time decoding of visual stimuli such as natural and synthetic video streams (movies, animation). The architecture for time encoding is akin to models of the early visual system. It consists of a bank of filters in cascade with single-input multi-output neural circuits. Neuron firing is based on either a threshold-and-fire or an integrate-and-fire spiking mechanism with feedback. We show that analog information is represented by the neural circuits as projections on a set of band-limited functions determined by the spike sequence. Under Nyquist-type and frame conditions, the encoded signal can be recovered from these projections with arbitrary precision. For the video time encoding machine architecture, we demonstrate that band-limited video streams of finite energy can be faithfully recovered from the spike trains and provide a stable algorithm for perfect recovery. The key condition for recovery calls for the number of neurons in the population to be above a threshold value. PMID:21296708

  18. Correlating Aluminum Burning Times

    Microsoft Academic Search

    M. W. Beckstead

    2005-01-01

    Characteristics of aluminum combustion are summarized in an overview of the subject, focusing on the burning time of individual particles. Combustion data from over ten different sources with almost 400 datum points have been cataloged and correlated. Available models have also been used to evaluate combustion trends with key environmental parameters. The fundamental concepts that control aluminum combustion are discussed,

  19. 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.

  20. Time-reversal acoustics

    Microsoft Academic Search

    Mathias Fink

    2008-01-01

    Time-reversal mirrors (TRMs) refocus an incident acoustic field to the position of the original source regardless of the complexity of the propagation medium. TRM's have now been implemented in a variety of physical scenarios from MHz ultrasonics with order centimeter aperture size to hundreds\\/thousands of Hz in ocean acoustics with order hundred meter aperture size. Common to this broad range

  1. A Moment in Time

    ERIC Educational Resources Information Center

    Lonergan, David

    2013-01-01

    There is a growing literature on the disappearance of the traditional model of higher education. Fewer courses are taught now than was the case just a few years ago by a full-time, permanent instructor in a single location, to students that the instructor has actually met in person. Another very real threat to the range of education is the growing…

  2. A Walk through Time.

    ERIC Educational Resources Information Center

    Renfroe, Mark; Letendre, Wanda

    1996-01-01

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

  3. 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…

  4. NTP Precision Time Synchronization

    E-print Network

    Mills, David L.

    timing sources using GPS, LORAN-C and cesium clocks. #12;Part 1 ­ quick fixes Assess errors due to kernel[Offsetdata are from other sources ­ The interesting observation is that these lines are almost straight, but with different slope. ­ The awesome fact

  5. Time Management Randy Pausch

    E-print Network

    ?): that's why this is on the WWW · Faculty vs. Grad Students vs. Undergrads · Lightning pace, heavy clear: focus on one thing at a time · A good file system is essential · Touch each piece of paper once that this refers to periodicals and routine reading, which is different than a research dig #12;38 Office Logistics

  6. 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 about complicated choreography-just get into the rhythm and sweat like you never have before! 60 minute on a first come first serve basis. All fitness and experience levels welcome at all classes! No registration

  7. The virtual time machine

    Microsoft Academic Search

    Richard M. Fujimoto

    1989-01-01

    A parallel computer architecture is proposed that is based on an optimistic style of execution. Specifically, the Virtual Time Machine (VTM) detects violations of data depen- dence constraints at runtime, and automatically recovers from them. In order to efficiently implement this mecha- nism, a sophisticated, two-dimensional memory system is proposed that is addressed using both a spatial and a tern.

  8. Infinite Time Turing Machines

    Microsoft Academic Search

    Joel David Hamkins; Andy Lewis

    2000-01-01

    We extend in a natural way the operation of Turing machines to infinite ordinal time, and investigate the resulting supertask theory of computability and decidability on the reals. Every ?11 set, for example, is decidable by such machines, and the semi-decidable sets form a portion of the ?12 sets. Our oracle concept leads to a notion of relative computability for

  9. Geological Time Machine

    NSDL National Science Digital Library

    Allen Collins

    This University of California site provides an interactive geologic time scale to explore the history of the Earth. Beginning in the Precambrian Eon (4.6 million years ago) and ending today (Holocene Epoch), each Epoch, Period, Era, and Eon are covered. Information provided includes ancient life, dates, descriptions of major events, localities, tectonics, and stratigraphy. Links to additional resources are also available.

  10. 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.

  11. Eliminating Timing Information Flows

    E-print Network

    Sherwood, Tim

    Eliminating Timing Information Flows in a Mix-Trusted System-on-Chip Jason Oberg and Ryan Kastner SYSTEMS GOVERN some of the most critical aspects of our lives. These high-assurance systems, which are found in medical devices, auto- mobiles, planes, satellites, and military systems, have an extremely

  12. 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

  13. Meteorology 5323 Time Series Analysis

    E-print Network

    Droegemeier, Kelvin K.

    Meteorology 5323 Time Series Analysis Fall Semester 2012 MWF 11:00 ­ 11:50 am Room 5600 NWC Course of time series. At the same time we want to use time series analyses to gain insight into the physical understanding of basic time series terminology and methodology to better deal with more advanced time series

  14. Stop wasting valuable time.

    PubMed

    Mankins, Michael C

    2004-09-01

    Companies routinely squander their most precious resource--the time of their top executives. In the typical company, senior executives meet to discuss strategy for only three hours a month. And that time is poorly spent in diffuse discussions never even meant to result in any decision. The price of misused executive time is high. Delayed strategic decisions lead to overlooked waste and high costs, harmful cost reductions, missed new product and business development opportunities, and poor long-term investments. But a few deceptively simple changes in the way top management teams set agendas and structure team meetings can make an enormous difference in their effectiveness. Efficient companies use seven techniques to make the most of the time their top executives spend together. They keep strategy meetings separate from meetings focused on operations. They explore issues through written communications before they meet, so that meeting time is used solely for reaching decisions. In setting agendas, they rank the importance of each item according to its potential to create value for the company. They seek to get issues not only on, but also off, the agenda quickly, keeping to a clear implementation timetable. They make sure they have considered all viable alternatives before deciding a course of action. They use a common language and methodology for reaching decisions. And they insist that, once a decision is made, they stick to it--that there be no more debate or mere grudging compliance. Once leadership teams get the basics right, they can make more fundamental changes in the way they work together. Strategy making can be transformed from a series of fragmented and unproductive events into a streamlined, effective, and continuing management dialogue. In companies that have done this, management meetings aren't a necessary evil; they're a source of real competitive advantage. PMID:15449855

  15. 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.

  16. 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.

  17. Skewed Autonomy-Relatedness in Preadolescents' Conceptions of Their Relationships with Mother, Father, and Best Friend.

    ERIC Educational Resources Information Center

    Hodges, Ernest V. E.; Finnegan, Regina A.; Perry, David G.

    1999-01-01

    Examined the balance between connectedness to, and independence from, mother, father, and best friend in 9- to 14-year olds. Found that children reporting a preoccupied or avoidant stance toward their mother displayed increased social impairment in the peer group over time. Stances toward mother, father, and best friend were related. Children…

  18. Swing leg retraction helps biped walking stability M. Wisse*, C. G. Atkeson, D. K. Kloimwieder

    E-print Network

    Atkeson, Christopher G.

    inverted pendulum model for the stance leg. The swing leg is assumed to accurately follow a time feel that the motion of the hand and ball is analogous to that of the swing leg and stance legSwing leg retraction helps biped walking stability M. Wisse*, C. G. Atkeson, D. K. Kloimwieder

  19. A Simple Controller for Quadrupedal Bounding Xin Liu and Ioannis Poulakakis

    E-print Network

    Poulakakis, Ioannis

    leg stance phases, and a continuous-time con- troller is proposed that stabilizes the energy to study bounding. In this model, the legs are assumed massless and actuation is introduced at the hips during the front and back leg stance phases to develop non-conservative correc- tive action

  20. Time Dependent Volcano Deformation

    NASA Astrophysics Data System (ADS)

    Segall, P.

    2006-12-01

    Time varying deformation can arise due to changes in magma pressure, evolution of the source geometry (e.g., dike propagation), or time dependent response of the surrounding crust. It is important to understand the signatures of these processes in order to distinguish between them. Here I explore time dependent surface deformation due to viscoelastic and poroelastic relaxation of the crust surrounding simplified magma chambers. Viscoelastic deformation is considered in a shell surrounding a spherical magma chamber in a half-space (as analyzed numerically by Newman et al, 2001). The full space solution for a Maxwell rheology was given by Dragoni and Magnanensi (PEPI, 1989). An approximate half-space solution is simply constructed following the approach of McTigue (JGR, 1987) as long as the outer radius R2 is small compared to the depth d. The surface displacements are scaled, time-dependent versions of the Mogi solution in an elastic half-space. For a step increase in magma pressure (other source histories are also simply constructed) uz (?, z=0, t) = (1 - ?) p0 R13 / ? d2 [ e-t/tR + R23 / R13 ( 1 - e-t/tR ) ] 1 / (1 + ?2)3/2 where R1 is the magma chamber radius, ? is the normalized radial distance from the center of the source, and the characteristic relaxation time is tR = (3?/?)(1-?)/(1+?)(R2/R1)3, where ? is viscosity and ? is shear modulus. The post-intrusion displacements scale with (R2/R1)3 - 1 and can be significant. For example, a viscoelastic shell of only 20% the radius of the magma chamber leads to time dependent displacements that are 70% of the instantaneous elastic displacements. An approximate fully time-dependent solution for a cylindrical (plane strain) magma chamber in a homogeneous poro-elastic half-space is constructed as the superposition of the solution due to an expanding chamber in a full plane, and distributed shear and normal loads on a poroelastic half-space. The full-space solution is pure shear and thus induces no change in pore pressure. Consequently, the distributed loads necessary to cancel the imposed tractions on the free surface are time invariant. The surface displacements due to the applied surface loads are found using displacement potentials in the Fourier-Laplace domain; the Laplace transforms are inverted analytically. The vertical velocity resulting from the instantaneous inflation of the magma chamber is 2 ? vz(z=0,t) = ? (1-?) [ N? - i sgn(k) T? ] ? c/? t e- c k2 t - c k ?1-? e-? c k2 terfc( ?c (1-?) k2 t) where k is horizontal wavenumber, c is hydraulic diffusivity, ?{1-?} = 1-2?2, ?2 = ?u - ?/1-? , ?u is the undrained Poisson's ratio, and N? and T? are the Fourier transformed normal N and shear T tractions acting on the plane z = 0, N = (? ? V/? ) (x2- d2) /(d2 + x2)2, T = (2? ? V/ ? )dx/(d2 + x2)2. The displacement immediately above the source increases monotonically, however the flanking regions subside for some time following the initial elastic uplift before further uplifting. This arises because pore fluid flows from the flanking region to the center of uplift. The final uplift is identical to the initial elastic uplift but increased by a factor of ?u-?.

  1. FROM TIME-TRIGGERED TO TIME-DETERMINISTIC REAL-TIME SYSTEMS

    E-print Network

    FROM TIME-TRIGGERED TO TIME-DETERMINISTIC REAL-TIME SYSTEMS Peter Puschner and Raimund Kirner presents a very rigid software execution model for building dis- tributed hard real-time subsystems the operations of the hard real- time subsystem in synchrony with the real-time environment. The proposed

  2. Real time process algebra with time-dependent conditions

    Microsoft Academic Search

    Jos C. M. Baeten; C. A. Middelburg

    2001-01-01

    We add conditionals with time-dependent conditions to the real time process algebra with para- metric timing from the framework of process algebras with timing presented by Baeten and Middel- burg (Handbook of Process Algebra, Elsevier, 2001, Chapter 10). This extension facilitates flexible dependence of process behaviour on initialization time. We show that the conditions concerned gen- eralize the conditions introduced

  3. Structural Translation from Time Petri Nets to Timed Automata

    Microsoft Academic Search

    Franck Cassez; Olivier-H. Roux

    2005-01-01

    In this paper, we consider Time Petri Nets (TPN) where time is associated with transitions. We give a formal semantics for TPNs in terms of Timed Transition Systems. Then, we propose a translation from TPNs to Timed Automata (TA) that preserves the behavioral semantics (timed bisimilarity) of the TPNs. For the theory of TPNs this result is twofold: (i) reachability

  4. Structural translation from Time Petri Nets to Timed Automata

    Microsoft Academic Search

    Franck Cassez; Olivier H. Roux

    2006-01-01

    Abstract In this paper, we consider Time Petri Nets (TPN) where time is associated with transitions. We give a formal semantics for TPNs in terms of Timed Transition Systems. Then, we propose a translation from TPNs to Timed Automata (TA) that preserves the behavioral semantics,(timed bisimilarity) of the TPNs. For the theory of TPNs this result is twofold: (i) reachability

  5. Structural Translation from Time Petri Nets to Timed Automata

    E-print Network

    Paris-Sud XI, Université de

    Structural Translation from Time Petri Nets to Timed Automata Franck Cassez and Olivier H. Roux consider Time Petri Nets (TPN) where time is associated with transitions. We give a formal semantics-of-the-art tool for analyzing TPNs. 1 Introduction Petri Nets with Time. The two main extensions of Petri Nets

  6. TART: Timed-Automata to Real-Time Java Tool

    Microsoft Academic Search

    Niusha Hakimipour; Paul Strooper; Andy Wellings

    2010-01-01

    In previous work, we have proposed a model based approach to developing real-time Java programs from timed automata. This approach allows us to verify the timed automata model mechanically by using current real-time model checking tools. Programs are then derived from the model by following a systematic approach. TART (timed automata to RTSJ Tool) is a prototype tool to support

  7. An efficient time representation for real-time embedded systems

    Microsoft Academic Search

    Alessio Carlini; Giorgio C. Buttazzo

    2003-01-01

    Real-time systems should provide a time representation mechanism which allows to specify timing constraints in a wide range and with sufficiently high resolution. Moreover, the system lifetime (that is, the longest absolute time that can be handled by the system) should be as long as possible, or possibly infinite. In powerful architectures, this goal is achieved by representing time through

  8. Estimating probabilistic timing performance for real-time embedded systems

    Microsoft Academic Search

    Xiaobo Sharon Hu; Tao Zhou; Edwin Hsing-mean Sha

    2001-01-01

    In system-level design of real-time embedded systems, being able to capture the interactions among the tasks with respect to timing constraints and determine the overall system timing performance is a major challenge. Most previous works in the area are either based on a fixed execution time model or are only concerned with the probabilistic timing behavior of each individual task.

  9. Minimizing Busy Time in Multiple Machine Real-time Scheduling

    E-print Network

    Shachnai, Hadas

    Minimizing Busy Time in Multiple Machine Real-time Scheduling Rohit Khandekar1 , Baruch Schieber1 with a release time, a due date, a processing time and demand for machine capacity. The goal is to schedule all of the jobs non-preemptively in their release-time-deadline windows, subject to machine capacity constraints

  10. TEK: Time Equals Knowledge

    NSDL National Science Digital Library

    Time Equals Knowledge (TEK) is a project at the Massachusetts Institute of Technology that is developing "a low-connectivity search engine for use by people at the far side of a bad telephone connection." Intended primarily for less developed countries where Internet access is limited and slow, the TEK client allows users to submit search queries and retrieve compressed Web content relevant to their query at a later time. A complete overview of the system is given on the project's homepage. A few publications detailing TEK research are available, and the TEK client itself can be downloaded. However, the client is currently a work in progress and is mainly recommended for experienced software testers.

  11. Time and Citation Networks

    E-print Network

    Clough, James R

    2015-01-01

    Citation networks emerge from a number of different social systems, such as academia (from published papers), business (through patents) and law (through legal judgements). A citation represents a transfer of information, and so studying the structure of the citation network will help us understand how knowledge is passed on. What distinguishes citation networks from other networks is time; documents can only cite older documents. We propose that existing network measures do not take account of the strong constraint imposed by time. We will illustrate our approach with two types of causally aware analysis. We apply our methods to the citation networks formed by academic papers on the arXiv, to US patents and to US Supreme Court judgements. We show that our tools can reveal that citation networks which appear to have very similar structure by standard network measures turn out to have significantly different properties. We interpret our results as indicating that many papers in a bibliography were not directly...

  12. 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

  13. Reaction Time 2: Zap!

    NSDL National Science Digital Library

    Science Netlinks

    2003-06-19

    This Science NetLinks lesson is the second of a two-part series that encourages students to think about their own learning and the strategies that best help them learn new skills and ideas. In this lesson, students build upon what they have already learned by participating in another online reaction-time activity--this one testing their visual and auditory abilities, both separately and together.

  14. Resonance with Stochastic Time

    NASA Astrophysics Data System (ADS)

    Ohira, Toru

    2010-06-01

    We introduce a resonant phenomenon using a model incorporating delay (temporal non-locality) and stochastic time (temporal stochasticity). Although this model is a very simple linear dynamical differential equation, the addition of these elements makes it very rich. As an illustrative example, we describe a human stick balancing experiment that includes added fluctuations. We discuss how these concepts of temporal non-locality and stochasticity could play a role in characterizing biological and physiological systems, as well as in physics.

  15. 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.

  16. 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.

  17. Gravity, Time, and Lagrangians

    ERIC Educational Resources Information Center

    Huggins, Elisha

    2010-01-01

    Feynman mentioned to us that he understood a topic in physics if he could explain it to a college freshman, a high school student, or a dinner guest. Here we will discuss two topics that took us a while to get to that level. One is the relationship between gravity and time. The other is the minus sign that appears in the Lagrangian. (Why would one…

  18. Music in Galileo's Time

    NASA Astrophysics Data System (ADS)

    Petrobelli, P.

    2011-06-01

    Claudio Monteverdi appears as the key personality of the music in Galileo's time. His revolution in format and function of the musical language-from an essentially edonistic creation of purely sonorous images to a musical language consciously "expressive" of the content of the words on which it is based-is similar in character to the influential innovations in scientific thinking operated by Galileo.

  19. Time Processing in Dyscalculia

    PubMed Central

    Cappelletti, Marinella; Freeman, Elliot D.; Butterworth, Brian L.

    2011-01-01

    To test whether atypical number development may affect other types of quantity processing, we investigated temporal discrimination in adults with developmental dyscalculia (DD). This also allowed us to test whether number and time may be sub-served by a common quantity system or decision mechanisms: if they do, both should be impaired in dyscalculia, but if number and time are distinct they should dissociate. Participants judged which of two successively presented horizontal lines was longer in duration, the first line being preceded by either a small or a large number prime (“1” or “9”) or by a neutral symbol (“#”), or in a third task participants decided which of two Arabic numbers (either “1,” “5,” “9”) lasted longer. Results showed that (i) DD’s temporal discriminability was normal as long as numbers were not part of the experimental design, even as task-irrelevant stimuli; however (ii) task-irrelevant numbers dramatically disrupted DD’s temporal discriminability the more their salience increased, though the actual magnitude of the numbers had no effect; in contrast (iii) controls’ time perception was robust to the presence of numbers but modulated by numerical quantity: therefore small number primes or numerical stimuli seemed to make durations appear shorter than veridical, but longer for larger numerical prime or numerical stimuli. This study is the first to show spared temporal discrimination – a dimension of continuous quantity – in a population with a congenital number impairment. Our data reinforce the idea of a partially shared quantity system across numerical and temporal dimensions, which supports both dissociations and interactions among dimensions; however, they suggest that impaired number in DD is unlikely to originate from systems initially dedicated to continuous quantity processing like time. PMID:22194731

  20. Space Time Matter inflation

    E-print Network

    Mariano Anabitarte; Mauricio Bellini

    2006-02-20

    We study a model of power-law inflationary inflation using the Space-Time-Matter (STM) theory of gravity for a five dimensional (5D) canonical metric that describes an apparent vacuum. In this approach the expansion is governed by a single scalar (neutral) quantum field. In particular, we study the case where the power of expansion of the universe is $p \\gg 1$. This kind of model is more successful than others in accounting for galaxy formation.

  1. 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.

  2. [Real time quantitative PCR].

    PubMed

    Kim, D W

    2001-04-21

    So far, quantitative techniques, such as PCR and FISH, have been used to detect of DNA and RNA. However, it is difficult to measure and compare the exact amount of amplified products with the results of endpoint analysis in conventional PCR techniques. Theoretically, there is a quantitative relationship between amount of starting target sequence and amount of PCR product at any given cycle. The development of real-time quantitative PCR (RQ-PCR) has eliminated the variability associated with conventional quantitative PCR, thus allowing the routine and reliable quantitation of PCR products. Detection of fluorescence during the thermal cycling process can be performed using iCycler(Bio-Rad), the GeneAmp 5700 or 7700(ABI-PRISM), and Light-Cycler(Roche). Two fluorogenic probes are available for use on real time quantitation. The fluorogenic 5'-nuclease assay(Taqman method) uses a fluorogenic probe to enable the detection of a sequence specific PCR product. Fluorogenic probe is incorporated with the reporter dye on the 5' end and the quencher on the 3' end. The second method uses SYBR Green I dye which is a highly specific double-stranded DNA binding dye. Real-time PCR is able to be possible exact quantitation of DNA and RNA much more precise and reproducible because it is based on CT values acquired during the exponential phase of PCR rather than endpoint. In this review, the detail protocol of real time quantitative PCR technique will be introduced and our recently developed system for exact quantitation of BCR-ABL fusion gene in CML is going to be described. PMID:11708318

  3. Swing in Time

    NSDL National Science Digital Library

    Sabre Duren

    2004-01-01

    Learners build and investigate pendulums of different lengths. They discover that the longer the string of the pendulum, the longer the time it takes to swing. Learners also discover that changing the mass on the end of the pendulum and changing the angle of release of the pendulum do not affect how long it takes to swing. Resource contains suggestions for assessment, extensions, and scaling for different levels of learners.

  4. Time Division Multiplexing

    NSDL National Science Digital Library

    Castro, Tony

    Created by Tony Castro of the Information and Communications Technologies Center (ICT), this simulation demonstrates time division multiplexing, in which "two or more apparently simultaneous channels are derived from a given frequency spectrum, i.e., bit stream, by interleaving pulses representing bits from different channels." This resource is a helpful addition to any course on information and communications technologies as it allows students to see exactly how the model works in information systems, and understand what distinguishes TDM from packet switching.

  5. Timing HU Aqr

    NASA Astrophysics Data System (ADS)

    Schwope, A.; Traulsen, I.; Hessman, F.; Thinius, B.; Walter, F.; Schwarz, R.; Reinsch, K.; Burwitz, V.

    2014-07-01

    We report XMM-Newton X-ray and ultraviolet observations of the bright eclipsing polar HU Aqr performed in October 2013. When discovered in the RASS, it was the brightest eclipsing AM Her star but in the XMM-Newton era it was encountered in low or intermediate states only. After recovery into a high state a triggered Swift/XMM-Newton accompanied by ground-based photometry could be arranged. The X-ray observations covered 5 orbital cycles of the 125min binary. The object was extremely bright at soft X-rays reaching >150 cts/s in 1s time bins. The X-ray light curve was found to be highly structured featuring an opaque accretion stream and a porous accretion curtain. We will present a multi-wavelength timing study to locate the X-ray emission region and determine its size. The relative timing of optical and X-ray eclipses and the use of either data searching for circumbinary planets via the Roemer delay is discussed.

  6. Time-reversal acoustics

    NASA Astrophysics Data System (ADS)

    Fink, Mathias

    2008-10-01

    Time-reversal mirrors (TRMs) refocus an incident acoustic field to the position of the original source regardless of the complexity of the propagation medium. TRM's have now been implemented in a variety of physical scenarios from MHz ultrasonics with order centimeter aperture size to hundreds/thousands of Hz in ocean acoustics with order hundred meter aperture size. Common to this broad range of scales is a remarkable robustness exemplified by observations at all scales that the more complex the medium between the probe source and the TRM, the sharper the focus. The relation between the medium complexity and the size of the focal spot is studied in this paper. It is certainly the most exciting property of TRM compared to standard focusing devices. A TRM acts as an antenna that uses complex environments to appears wider than it is, resulting for a broadband pulse in a refocusing quality that does not depend of the TRM aperture. In this paper, we investigate the time-reversal approach in various media of increasing complexity and we discuss the link existing between time-reversal approach and local helioseismology where Green's functions can be extracted from diffusive noise.

  7. Initial label: Time out In

    E-print Network

    van der Torre, Leon

    Any J Any J J N N 0 1 0 2 1 2 2 1 8 #12;9 #12;Born (init) Token Tree Member Token Time out RQT Token ACK SYN/ACK ACK Time out Time out In Move Token In Move Token Time out ACK RQT Token Wait SYN/ACK RQT 11 #12;Tree Member Token Time out RQT Token ACK SYN/ACK ACK Time out Time out In Move Token In Move

  8. A continuous time random walk model with multiple characteristic times

    NASA Astrophysics Data System (ADS)

    Sau Fa, Kwok; Mendes, R. S.

    2010-04-01

    In this paper we consider a continuous time random walk (CTRW) model with a decoupled jump pdf. Further, we consider an approximate jump length pdf; for the waiting time pdf we do not use any approximation and we employ a function which depends on multiple characteristic times given by a sum of exponential functions. This waiting time pdf can reproduce power-law behavior for intermediate times. Using this specific waiting time probability density, we analyze the behavior of the second moment generated by the CTRW model. It is known that the waiting time pdf given by an exponential function generates a normal diffusion process, but for our waiting time pdf the second moment can give an anomalous diffusion process for intermediate times, and the normal diffusion process is maintained for the long-time limit. We note that systems which present subdiffusive behavior for intermediate times but reach normal diffusion at large times have been observed in biology.

  9. Engaged Time in the Classroom

    ERIC Educational Resources Information Center

    Johns E., Beverly H.; Crowley, Paula; Guetzloe, Eleanor

    2008-01-01

    Foremost in an effective curriculum for students with emotional and behavioral disorder (E/BD) is a high level of engaged time--time spent doing meaningful learning activities. Engaged time (time-on-task) is the portion of instructional time that students spend directly involved in learning activities. Walker and Severson (1992) defined the…

  10. Television Programming during "People's Time."

    ERIC Educational Resources Information Center

    Austin, Bruce A.

    A study was initiated to answer questions concerning television programing during "people's time" in a medium-sized market. "People's time" is defined as local prime time from 4:00 p.m. to 8:00 p.m. as contrasted with prime or network time and is considered a time when local broadcasters have an opportunity to serve their audience's…

  11. Time Management Marek J. Druzdzel

    E-print Network

    Brusilovsky, Peter

    Time Management Marek J. Druzdzel with minor additions from Peter Brusilovsky University://www.pitt.edu/~druzdzel Time Management (and Really Important Things) Time Management Overview · How to use your time best? · How to manage stress? · What is really important? · Concluding remarks #12;Time Management How to use

  12. The brain and child development: time for some critical thinking.

    PubMed Central

    Bruer, J T

    1998-01-01

    There is widespread interest in the claim that new breakthroughs in neuroscience have radical implications for early child care policy. Yet despite parents', educators', and policy makers' enthusiasm, there are good reasons to be skeptical. The neuroscience cited in the policy arguments is not new, depending primarily on three well-established neurobiological findings: rapid postnatal synapse formation, critical periods in development, and the effects of enriched rearing on brain connectivity in rats. Furthermore, this neuroscience is often oversimplified and misinterpreted. While child care advocates are enthusiastic about potential applications of brain science, for the most part neuroscientists are more cautious and skeptical. After reviewing the evidence and the arguments, the author suggests that in the interest of good science and sound policy, more of us might adopt a skeptical stance. Images p388-a p389-a PMID:9769763

  13. Time to re-evaluate gender segregation in athletics?

    PubMed

    Foddy, Bennett; Savulescu, Julian

    2011-12-01

    The case of Caster Semenya provides a vivid illustration of the ways in which natural genetic variation can generate large differences in athletic performance. But since we normally segregate athletic sports along the lines of this particular variation-gender-her case also highlights problems with the current approach to justice in sporting competition. Female athletes seem to have a valid complaint when they are made to compete against athletes who are, in one sense or another, male. But once we recognise that gender is not a binary quantity, sex segregation in competitive sport must be seen as an inconsistent and unjust policy, no matter what stance we take on the goals of sport or on the regulation of doping. PMID:20702382

  14. Memory on time.

    PubMed

    Eichenbaum, Howard

    2013-02-01

    Considerable recent work has shown that the hippocampus is critical for remembering the order of events in distinct experiences, a defining feature of episodic memory. Correspondingly, hippocampal neuronal activity can 'replay' sequential events in memories and hippocampal neuronal ensembles represent a gradually changing temporal context signal. Most strikingly, single hippocampal neurons - called time cells - encode moments in temporally structured experiences much as the well-known place cells encode locations in spatially structured experiences. These observations bridge largely disconnected literatures on the role of the hippocampus in episodic memory and spatial mapping, and suggest that the fundamental function of the hippocampus is to establish spatio-temporal frameworks for organizing memories. PMID:23318095

  15. Timing is Everything

    NSDL National Science Digital Library

    Debra Drury

    2006-07-01

    Kids today are growing up with televisions, movies, videos, and DVDs, so it's logical to assume that this type of media could be motivating and used to great effect in the classroom. But at what point should film and other visual media be used? Are there times in the inquiry process when showing a film or incorporating other visual media is more effective? One teacher tackles these questions by assessing video use among her upper-elementary students in a small rural Northeastern Missouri school district.

  16. The Time of Surak 

    E-print Network

    Multiple Contributors

    1979-01-01

    in THE SOUTHERN STAR #2 Enjoy your excursion into Vulcan's past— LIVE LONG AND PROSPER. ® raj VIR0C FOLLOW^ 5andra H. flecchi The Vulcan boy glared dimly at the lifeless desert surrounding the encampment of his clan, the Teelak. He had watched it several times... succeeded. The Teelak had been suspecting an attack but not one quite so soon and by an entirely different clan. It had been the Kain who ravaged them, brutally and with out any warning. It had been barely morning when they attacked and by the end of the day...

  17. 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.

  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. 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.

  20. Time Dilation Equation

    NSDL National Science Digital Library

    This online article is from the Museum's Seminars on Science, a series of distance-learning courses designed to help educators meet the new national science standards. The article, which offers a simple demonstration of Einstein's Time Dilation Equation, is part of the Frontiers in Physical Science seminar. It uses the example of a light beam bouncing between two mirrors in a rocket to illustrate the theory, and includes a step-by-step look at the math involved in calculating the quantitative solution.

  1. 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.

  2. Real time SAR processing

    NASA Technical Reports Server (NTRS)

    Premkumar, A. B.; Purviance, J. E.

    1990-01-01

    A simplified model for the SAR imaging problem is presented. The model is based on the geometry of the SAR system. Using this model an expression for the entire phase history of the received SAR signal is formulated. From the phase history, it is shown that the range and the azimuth coordinates for a point target image can be obtained by processing the phase information during the intrapulse and interpulse periods respectively. An architecture for a VLSI implementation for the SAR signal processor is presented which generates images in real time. The architecture uses a small number of chips, a new correlation processor, and an efficient azimuth correlation process.

  3. Biotechnology Through Time

    NSDL National Science Digital Library

    The Children's Museum of Indianapolis

    2007-01-01

    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.

  4. TIMED Imaging Photometer Experiment (TIPE)

    NASA Technical Reports Server (NTRS)

    Mende, Stephen B.; Fritts, D. C.; Hecht, James H.; Killeen, T. L.; Llewellyn, Edward J.; Lowe, Robert P.; Mcdade, Ian C.; Ross, Martin N.; Swenson, Gary R.; Turnbull, David N.

    1994-01-01

    This document contains a summary of the TIMED Imaging Photometer Experiment (TIPE) instrument study at the time of the termination of project due to TIPE being de-selected from the Thermosphere, Ionosphere and Mesosphere Energetics and Dynamics (TIMED) mission.

  5. Introduction Nonlinear time series analysis

    E-print Network

    Savicky, Petr

    Introduction Nonlinear time series analysis Summary Quantifying Interactions between Complex Oscillatory Systems: A Topic in Time Series Analysis Thesis defense presentation M. Vejmelka, supervisor M;Introduction Nonlinear time series analysis Summary Overview Weak interactions between pairs of systems Focus

  6. Moments in Time

    PubMed Central

    Wittmann, Marc

    2011-01-01

    It has been suggested that perception and action can be understood as evolving in temporal epochs or sequential processing units. Successive events are fused into units forming a unitary experience or “psychological present.” Studies have identified several temporal integration levels on different time scales which are fundamental for our understanding of behavior and subjective experience. In recent literature concerning the philosophy and neuroscience of consciousness these separate temporal processing levels are not always precisely distinguished. Therefore, empirical evidence from psychophysics and neuropsychology on these distinct temporal processing levels is presented and discussed within philosophical conceptualizations of time experience. On an elementary level, one can identify a functional moment, a basic temporal building block of perception in the range of milliseconds that defines simultaneity and succession. Below a certain threshold temporal order is not perceived, individual events are processed as co-temporal. On a second level, an experienced moment, which is based on temporal integration of up to a few seconds, has been reported in many qualitatively different experiments in perception and action. It has been suggested that this segmental processing mechanism creates temporal windows that provide a logistical basis for conscious representation and the experience of nowness. On a third level of integration, continuity of experience is enabled by working memory in the range of multiple seconds allowing the maintenance of cognitive operations and emotional feelings, leading to mental presence, a temporal window of an individual’s experienced presence. PMID:22022310

  7. Timing of cyber conflict

    PubMed Central

    Axelrod, Robert; Iliev, Rumen

    2014-01-01

    Nations are accumulating cyber resources in the form of stockpiles of zero-day exploits as well as other novel methods of engaging in future cyber conflict against selected targets. This paper analyzes the optimal timing for the use of such cyber resources. A simple mathematical model is offered to clarify how the timing of such a choice can depend on the stakes involved in the present situation, as well as the characteristics of the resource for exploitation. The model deals with the question of when the resource should be used given that its use today may well prevent it from being available for use later. The analysis provides concepts, theory, applications, and distinctions to promote the understanding strategy aspects of cyber conflict. Case studies include the Stuxnet attack on Iran’s nuclear program, the Iranian cyber attack on the energy firm Saudi Aramco, the persistent cyber espionage carried out by the Chinese military, and an analogous case of economic coercion by China in a dispute with Japan. The effects of the rapidly expanding market for zero-day exploits are also analyzed. The goal of the paper is to promote the understanding of this domain of cyber conflict to mitigate the harm it can do, and harness the capabilities it can provide. PMID:24474752

  8. The Sun in Time

    NASA Technical Reports Server (NTRS)

    Adams, Mitzi L.; Bero, Elizabeth; Sever, Thomas L.

    1999-01-01

    Leveraging funds from NASA's Initiative to Develop Education through Astronomy and Space Science (IDEAS) program, we combined the expertise of an archaeoastronomer, a solar scientist, and a teacher to trace humankind's view of the Sun and how that has changed, from the time of Stonehenge in about 1800 B.C.E., to the time of the Maya in 700 C.E., up to the modem era. Our program was aimed at middle-school students in an attempt to explain not only how science is done today, but how science has evolved from the observations of ancient societies. From these varied cultures, we touched on methods of observing the Sun, ideas of the composition of the Sun, and the relationship of the Sun to everyday life. Further, using the von Braun Astronomical Society's Planetarium in Huntsville, Alabama as a test-bed for the program, we illustrated concepts such as solstices, equinoxes, and local noon with approximately 800 eighth grade students from the local area. Our presentation to SEPA will include a description of NASA's IDEAS program and how to go about partnering with a NASA astronomer, some slides from our planetarium program and web-site, and some hands-on activities.

  9. DNA Replication Timing

    PubMed Central

    Rhind, Nicholas; Gilbert, David M.

    2015-01-01

    Patterns of replication within eukaryotic genomes correlate with gene expression, chromatin structure, and genome evolution. Recent advances in genome-scale mapping of replication kinetics have allowed these correlations to be explored in many species, cell types, and growth conditions, and these large data sets have allowed quantitative and computational analyses. One striking new correlation to emerge from these analyses is between replication timing and the three-dimensional structure of chromosomes. This correlation, which is significantly stronger than with any single histone modification or chromosome-binding protein, suggests that replication timing is controlled at the level of chromosomal domains. This conclusion dovetails with parallel work on the heterogeneity of origin firing and the competition between origins for limiting activators to suggest a model in which the stochastic probability of individual origin firing is modulated by chromosomal domain structure to produce patterns of replication. Whether these patterns have inherent biological functions or simply reflect higher-order genome structure is an open question. PMID:23838440

  10. Timing of cyber conflict.

    PubMed

    Axelrod, Robert; Iliev, Rumen

    2014-01-28

    Nations are accumulating cyber resources in the form of stockpiles of zero-day exploits as well as other novel methods of engaging in future cyber conflict against selected targets. This paper analyzes the optimal timing for the use of such cyber resources. A simple mathematical model is offered to clarify how the timing of such a choice can depend on the stakes involved in the present situation, as well as the characteristics of the resource for exploitation. The model deals with the question of when the resource should be used given that its use today may well prevent it from being available for use later. The analysis provides concepts, theory, applications, and distinctions to promote the understanding strategy aspects of cyber conflict. Case studies include the Stuxnet attack on Iran's nuclear program, the Iranian cyber attack on the energy firm Saudi Aramco, the persistent cyber espionage carried out by the Chinese military, and an analogous case of economic coercion by China in a dispute with Japan. The effects of the rapidly expanding market for zero-day exploits are also analyzed. The goal of the paper is to promote the understanding of this domain of cyber conflict to mitigate the harm it can do, and harness the capabilities it can provide. PMID:24474752

  11. Time-Constrained Machine Translation

    Microsoft Academic Search

    Janine Toole; Davide Turcato; Fred Popowich; Dan Fass; Paul Mcfetridge

    1998-01-01

    This paper defines the class of time-constrained applications: applications in which the user has limited time to process the system output. This class is differentiated\\u000a from real-time systems, where it is production time rather than comprehension time that is constrained. Examples of time-constrained MT\\u000a applications include the translation of multi-party dialogue and the translation of closed-captions. The constraints on comprehension

  12. Page 1 of 3 Adding a Punch or Reconciling Time for Time Stamp and Time Clock

    E-print Network

    Hutcheon, James M.

    Page 1 of 3 Adding a Punch or Reconciling Time for Time Stamp and Time Clock Users A punch will punch in and out. 1) Click My QuickNavs Tab. Select Reconcile Time . 2) If an employee does not appear, SAVE it, and even approve their time card. The Missed Punch column will highlight which of your

  13. Time, Place, and Content 53 Time, Place, and Content

    E-print Network

    Cook, Robert

    Time, Place, and Content 53 Time, Place, and Content Jonathon D. Crystal University of Georgia The goal of this article is to integrate information about basic mechanisms of time perception with research on time-place learning and research on the discrimination of what, when, and where (WWW). Several

  14. Developing Improved Travel Time Reliability Measures For Real-time

    E-print Network

    Bertini, Robert L.

    Developing Improved Travel Time Reliability Measures For Real-time And Archived ITS Data Applications Robert L. Bertini and Kate Lyman ITS Europe, Aalborg, Denmark June 20, 2007 #12; Travel time estimation more important Measure of consistency of trip's travel time Need for reliability indices More

  15. Calculating the Maximum Execution Time of Real-Time Programs

    Microsoft Academic Search

    Peter P. Puschner; Christian Koza

    1989-01-01

    In real-time systems, the timing behavior is an important property of each task. It has to be guaranteed that the execution of a task does not take longer than the specified amount of time. Thus, a knowledge about the maximum execution time of programs is of utmost importance.

  16. 50 Years of Time Parallel Time Integration Martin J. Gander

    E-print Network

    Gander, Martin J.

    parallel methods. Martin J. Gander Section of Mathematics, University of Geneva, Rue du Lievre 2-4, CP 6450 Years of Time Parallel Time Integration Martin J. Gander Abstract Time parallel time integration methods have received renewed interest over the last decade because of the advent of massively parallel

  17. Use of precision time and time interval (PTTI)

    NASA Technical Reports Server (NTRS)

    Taylor, J. D.

    1974-01-01

    A review of range time synchronization methods are discussed as an important aspect of range operations. The overall capabilities of various missile ranges to determine precise time of day by synchronizing to available references and applying this time point to instrumentation for time interval measurements are described.

  18. Jazz Old Time Online

    NSDL National Science Digital Library

    For fans of jazz, the Jazz Old Time site will be a fun way to listen to few well-known chestnuts from the early days of this musical idiom. Of course, those who don't know much about jazz will appreciate listening to a few new artists as well. The site features over 18,000 songs in the public domain, and visitors can browse through the selections by artists or take a look at a few sample playlists. As one might suspect, artists like King Oliver, Meade Lux Lewis, and Louis Armstrong are featured prominently, though early recordings from later artists, such as Stan Getz, are also available. The site might also be recommended to students in a music appreciation course.

  19. Denoising Deterministic Time Series

    E-print Network

    Steven P. Lalley; Andrew B. Nobel

    2006-04-21

    This paper is concerned with the problem of recovering a finite, deterministic time series from observations that are corrupted by additive, independent noise. A distinctive feature of this problem is that the available data exhibit long-range dependence and, as a consequence, existing statistical theory and methods are not readily applicable. This paper gives an analysis of the denoising problem that extends recent work of Lalley, but begins from first principles. Both positive and negative results are established. The positive results show that denoising is possible under somewhat restrictive conditions on the additive noise. The negative results show that, under more general conditions on the noise, no procedure can recover the underlying deterministic series.

  20. TIMED solar EUV experiment

    NASA Astrophysics Data System (ADS)

    Woods, Thomas N.; Bailey, Scott M.; Eparvier, Francis G.; Lawrence, George M.; Lean, Judith; McClintock, William E.; Roble, Raymond G.; Rottman, Gary J.; Solomon, Stanley C.; Tobiska, W. K.; Ucker, Gregory J.; White, O. R.

    1998-11-01

    The solar EUV experiment (SEE) selected for the NASA Thermosphere, Ionosphere, and Mesosphere Energetics and Dynamics mission will measure the solar vacuum UV (VUV) spectral irradiance from 0.1 to 200 nm. To cover this wide spectral range two different types of instruments are used: grating spectrograph for spectra above 25 nm and a set of silicon soft x-ray (XUV) photodiodes with thin film filters for below 30 nm. Redundant channels of the spectrograph and XUV photodiodes provide in-flight calibration checks on the time scale of a week, and annual rocket underflight measurements provide absolute calibration checks traceable to radiometric standards. Both types of instrument have been developed and flight proven as part of a NASA solar EUV irradiance rocket experiment.

  1. A Journey Through Time

    NSDL National Science Digital Library

    Lanting, Frans

    Noted photographer Frans Lanting opens the website dedicated to his most recent ambitious project with these words: "Seven years ago I stood at the tide line of an estuary and began a personal journey through time.� Auspicious words indeed, and this lovely exploration of what he found on this journey takes visitors on a "lyrical interpretation of life on Earth from its earliest beginnings to its present diversity.� As visitors click on the words "Start Journey" they will be taken through eighty six photographs which document the various physical landforms and processes from the Hawaiian Islands to the heights of the Himalayas. After clicking on each photo, visitors will be presented with an interactive timeline that locates the photo within a timeline of geologic history. Interested parties can also peruse the "More about LIFE" section to learn more about the equipment Lanting uses in his work, and how the project came to life.

  2. Time encoded radiation imaging

    DOEpatents

    Marleau, Peter; Brubaker, Erik; Kiff, Scott

    2014-10-21

    The various technologies presented herein relate to detecting nuclear material at a large stand-off distance. An imaging system is presented which can detect nuclear material by utilizing time encoded imaging relating to maximum and minimum radiation particle counts rates. The imaging system is integrated with a data acquisition system that can utilize variations in photon pulse shape to discriminate between neutron and gamma-ray interactions. Modulation in the detected neutron count rates as a function of the angular orientation of the detector due to attenuation of neighboring detectors is utilized to reconstruct the neutron source distribution over 360 degrees around the imaging system. Neutrons (e.g., fast neutrons) and/or gamma-rays are incident upon scintillation material in the imager, the photons generated by the scintillation material are converted to electrical energy from which the respective neutrons/gamma rays can be determined and, accordingly, a direction to, and the location of, a radiation source identified.

  3. On time reversal mirrors

    NASA Astrophysics Data System (ADS)

    Fannjiang, Albert C.

    2009-09-01

    The concept of time reversal (TR) of a scalar wave is reexamined from basic principles. Five different time-reversal mirrors (TRMs) are introduced and their relations are analyzed. For the boundary behavior, it is shown that for a paraxial wave only the monopole TR scheme satisfies the exact boundary condition while for the spherical wave only the MD-mode TR scheme satisfies the exact boundary condition. The asymptotic analysis of the near-field focusing property is presented for two dimensions and three dimensions. It is shown that to have a subwavelength focal spot, the TRM should consist of dipole transducers. The transverse resolution of the dipole TRM is linearly proportional to the distance between the point source and the TRM. The mixed mode TRM has the similar (linear) behavior in three dimensions, but in two dimensions the transverse resolution behaves as the square root of the distance between the point source and the TRM. The monopole TRM is ineffective in focusing below the wavelength. Contrary to the matched field processing and the phase processor, both of which resemble TR, TR in a weak- or non-scattering medium is usually biased in the longitudinal direction, especially when TR is carried out on a single plane with a finite aperture. This is true for all five TR schemes. On the other hand, the TR focal spot has been shown repeatedly in the literature, both theoretically and experimentally, to be centered at the source point when the medium is multiple scattering. A reconciliation of the two seemingly conflicting results is found in the random fluctuations in the intensity of the Green function for a multiple scattering medium and the notion of scattering-enlarged effective aperture.

  4. Timing Analysis of Real-Time Communication Under Electromagnetic Interference

    Microsoft Academic Search

    Ian Broster; Alan Burns; Guillermo Rodríguez-navas

    2005-01-01

    This paper discusses aspects of dependability of real-time communication. In particular, we consider timing behaviour under fault conditions for Controller Area Network (CAN) and the extension Time-triggered CAN (TTCAN) based on a time-driven schedule. We discuss the differences between these buses and their behaviour under electromagnetic interference. We present response timing analyses for CAN and TTCAN in the presence of

  5. Verifying Timing Properties for Distributed Real-Time Systems Using Timing Constraint Petri Nets

    Microsoft Academic Search

    Jeffrey J. P. Tsai; Stephen J. H. Yang; Yao-hsiung Chang; Eric Y. T. Juan

    1996-01-01

    Timing analysis is essential to the development of valid computer systems especially for a distributed real-time system. We present both static and dynamic analysis procedures to verify timing properties of distributed real-time systems using timing constraint Petri nets (TCPNs). With both derived static information and collected dynamic data, we can locate a faulty task in a distributed real-time system using

  6. Time's Ontic Voltage Craig Callender

    E-print Network

    Callender, Craig

    Time's Ontic Voltage Craig Callender Philosophy of time, as practiced throughout the last hundred venue for attacking questions about the nature of time--in sharp contrast to the primary venue slowly in philosophy of time.1 Since twentieth-century analytic philosophy as a whole often drew

  7. Calling all..... First Time Freshmen

    E-print Network

    de Lijser, Peter

    Calling all..... First Time Freshmen Open House June 19th 5:00pm-6:30pm First time Freshmen and number of people attending We welcome all First Time Freshmen to come and explore what awaits you at CSUF Irvine Campus!! All Academic Advisement for First Time Freshmen is done at the Fullerton Campus through

  8. Discrete Time Stochastic Petri Nets

    Microsoft Academic Search

    Michael K. Molloy

    1985-01-01

    Basic graph models of processes, such as Petri nets, have usually omitted the concept of time as a parameter. Time has been added to the Petri net model in two ways. The timed Petri net (TPN) uses a fixed number of discrete time intervals. The stochastic Petri net (SPN) uses an exponentially distributed random variable. In this paper, a discrete

  9. Time Ordering in Kicked Qubits

    E-print Network

    L. Kaplan; Kh. Kh. Shakov; A. Chalastaras; M. Maggio; A. L. Burin; J. H. McGuire

    2004-06-23

    We examine time ordering effects in strongly, suddenly perturbed two-state quantum systems (kicked qubits) by comparing results with time ordering to results without time ordering. Simple analytic expressions are given for state occupation amplitudes and probabilities for singly and multiply kicked qubits. We investigate the limit of no time ordering, which can differ in different representations.

  10. Time Series Hilary Term 2002

    E-print Network

    Time Series Hilary Term 2002 Dr. Gesine Reinert Outline 1. The nature of time series Types of data, examples, objectives, informal analysis, overview of tech- niques for time series analysis 2. Stationary, maximum-likelihood #12;tting, frequency domain 4. Some more advanced topics Multiple time series

  11. Time reversal of wideband microwaves

    Microsoft Academic Search

    G. Lerosey; J. de Rosny; A. Tourin; A. Derode; M. Fink

    2006-01-01

    In this letter, time reversal is applied to wideband electromagnetic waves in a reverberant room. To that end a multiantenna time reversal mirror (TRM) has been built. A 150 MHz bandwidth pulse at a central frequency of 2.45 GHz is radiated by a monopolar antenna, spread in time due to reverberation, recorded at the TRM, time reversed, and retransmitted. The

  12. Measurement-Based Timing Analysis

    NASA Astrophysics Data System (ADS)

    Wenzel, Ingomar; Kirner, Raimund; Rieder, Bernhard; Puschner, Peter

    In this paper we present a measurement-based worst-case execution time (WCET) analysis method. Exhaustive end-to-end execution-time measurements are computationally intractable in most cases. Therefore, we propose to measure execution times of subparts of the application code and then compose these times into a safe WCET bound.

  13. Redefining Time to Understand Space

    Microsoft Academic Search

    Thomas Sills

    2009-01-01

    In a new book, What Einstein Did Not See, Thomas W. Sills presents a new approach to both time and space. For the first time, readers see how Euclidean geometry can describe space with more than three dimensions. This new approach redefines time into two different component measurements: a vector of Timespace and a scalar of Universal Time. Three-dimensional projections

  14. Time reversal of wideband microwaves

    NASA Astrophysics Data System (ADS)

    Lerosey, G.; de Rosny, J.; Tourin, A.; Derode, A.; Fink, M.

    2006-04-01

    In this letter, time reversal is applied to wideband electromagnetic waves in a reverberant room. To that end a multiantenna time reversal mirror (TRM) has been built. A 150MHz bandwidth pulse at a central frequency of 2.45GHz is radiated by a monopolar antenna, spread in time due to reverberation, recorded at the TRM, time reversed, and retransmitted. The time-reversed wave converges back to its source and focus in both time and space. The time compression is studied versus the number of antennas in the TRM and its bandwidth. The focal spot is also measured thanks to an eight-channel receiving array.

  15. Flow of Time: Perceiving the passage of time: neural possibilities

    PubMed Central

    Muller, Timothy; Nobre, Anna C

    2014-01-01

    Although the study of time has been central to physics and philosophy for millennia, questions of how time is represented in the brain and how this representation is related to time perception have only recently started to be addressed. Emerging evidence subtly yet profoundly challenges our intuitive notions of time over short scales, offering insight into the nature of the brain's representation of time. Numerous different models, specified at the neural level, of how the brain may keep track of time have been proposed. These models differ in various ways, such as whether time is represented by a centralized or distributed neural system, or whether there are neural systems dedicated to the problem of timing. This paper reviews the insight offered by behavioral experiments and how these experiments refute and guide some of the various models of the brain's representation of time. PMID:25257798

  16. Diagnosis of Hold Time Defects

    Microsoft Academic Search

    Zhiyuan Wang; Malgorzata Marek-sadowska; Kun-han Tsai; Janusz Rajski

    2004-01-01

    In modern technologies, process variations can be quite substantial, often causing design timing failures. It is essential that those errors be correctly and quickly diag-nosed. In this work, we analyze failures caused by the hold-time-violations. We investigate the feasibility of using cir-cuit-timing information to guide the hold-time-fault diag-nosis. We propose a novel and efficient diagnostic approach based on timing window

  17. Real time polarimetric dehazing.

    PubMed

    Mudge, Jason; Virgen, Miguel

    2013-03-20

    Remote sensing is a rich topic due to its utility in gathering detailed accurate information from locations that are not economically feasible traveling destinations or are physically inaccessible. However, poor visibility over long path lengths is problematic for a variety of reasons. Haze induced by light scatter is one cause for poor visibility and is the focus of this article. Image haze comes about as a result of light scattering off particles and into the imaging path causing a haziness to appear on the image. Image processing using polarimetric information of light scatter can be used to mitigate image haze. An imaging polarimeter which provides the Stokes values in real time combined with a "dehazing" algorithm can automate image haze removal for instant applications. Example uses are to improve visual display providing on-the-spot detection or imbedding in an active control loop to improve viewing and tracking while on a moving platform. In addition, removing haze in this manner allows the trade space for a system operational waveband to be opened up to bands which are object matched and not necessarily restricted by scatter effects. PMID:23518739

  18. Dead-time optimized time-correlated photon counting instrument with synchronized, independent timing channels

    E-print Network

    Enderlein, Jörg

    Dead-time optimized time-correlated photon counting instrument with synchronized, independent timing channels Michael Wahla and Hans-Jürgen Rahn PicoQuant GmbH, Rudower Chaussee 29, D-12489 Berlin December 2006; accepted 19 February 2007; published online 23 March 2007 Time-correlated single photon

  19. When Are Timed Automata Weakly Timed Bisimilar to Time Petri Nets?

    Microsoft Academic Search

    Béatrice Bérard; Franck Cassez; Serge Haddad; Didier Lime; Olivier H. Roux

    2005-01-01

    In this paper, we compare Timed Automata (TA) with Time Petri Nets (TPN) with respect to weak timed bisimilarity. It is already known that the class of bounded TPNs is included in the class of TA. It is thus natural to try and identify the (strict) subclass T Awtb of TA that is equivalent to TPN for the weak time

  20. Real-time linked common-view time transfer for monitoring GNSS system time differences

    NASA Astrophysics Data System (ADS)

    Lee, Seung-Woo; Lee, Duk Kee; Lee, Young Jae

    2012-12-01

    This paper presents results obtained by conducting real-time linked common-view (CV) Global Navigation Satellite System (GNSS) time transfer between stations that are supposed to maintain various GNSS system times including those of GPS and Galileo. The distance between those stations is typically more than 5000 km and the conventional CV GPS time transfer may not be feasible for such long-distance time transfer. We used the real-time linked CV time transfer technique to monitor the GNSS system time differences, and the time links examined in this study are the USNO-PTB link for the GPS-Galileo system time difference and the USNO-NICT link for the GPS-QZSS system time difference. The performance of the developed time transfer method was assessed by comparing against other time transfer solutions such as TWSTFT. Finally, global closure was formed to examine the inherent noise level of the method in a self-sufficient way. Results showed that the real-time linked CV time transfer solution yields sub-nanosecond-level agreement with the reference solutions including TWSTFT, and its frequency stability is generally at the level of (3-4) × 10-15 in terms of the modified Allan deviation at the averaging time of one day, which seems to be sufficient to support civil interoperability between different GNSSs for sub-metre-level accuracy.