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Sample records for accuracy response time

  1. Response time accuracy in Apple Macintosh computers.

    PubMed

    Neath, Ian; Earle, Avery; Hallett, Darcy; Surprenant, Aimée M

    2011-06-01

    The accuracy and variability of response times (RTs) collected on stock Apple Macintosh computers using USB keyboards was assessed. A photodiode detected a change in the screen's luminosity and triggered a solenoid that pressed a key on the keyboard. The RTs collected in this way were reliable, but could be as much as 100 ms too long. The standard deviation of the measured RTs varied between 2.5 and 10 ms, and the distributions approximated a normal distribution. Surprisingly, two recent Apple-branded USB keyboards differed in their accuracy by as much as 20 ms. The most accurate RTs were collected when an external CRT was used to display the stimuli and Psychtoolbox was able to synchronize presentation with the screen refresh. We conclude that RTs collected on stock iMacs can detect a difference as small as 5-10 ms under realistic conditions, and this dictates which types of research should or should not use these systems.

  2. Speed-Accuracy Response Models: Scoring Rules Based on Response Time and Accuracy

    ERIC Educational Resources Information Center

    Maris, Gunter; van der Maas, Han

    2012-01-01

    Starting from an explicit scoring rule for time limit tasks incorporating both response time and accuracy, and a definite trade-off between speed and accuracy, a response model is derived. Since the scoring rule is interpreted as a sufficient statistic, the model belongs to the exponential family. The various marginal and conditional distributions…

  3. Modeling individual differences in response time and accuracy in numeracy.

    PubMed

    Ratcliff, Roger; Thompson, Clarissa A; McKoon, Gail

    2015-04-01

    In the study of numeracy, some hypotheses have been based on response time (RT) as a dependent variable and some on accuracy, and considerable controversy has arisen about the presence or absence of correlations between RT and accuracy, between RT or accuracy and individual differences like IQ and math ability, and between various numeracy tasks. In this article, we show that an integration of the two dependent variables is required, which we accomplish with a theory-based model of decision making. We report data from four tasks: numerosity discrimination, number discrimination, memory for two-digit numbers, and memory for three-digit numbers. Accuracy correlated across tasks, as did RTs. However, the negative correlations that might be expected between RT and accuracy were not obtained; if a subject was accurate, it did not mean that they were fast (and vice versa). When the diffusion decision-making model was applied to the data (Ratcliff, 1978), we found significant correlations across the tasks between the quality of the numeracy information (drift rate) driving the decision process and between the speed/accuracy criterion settings, suggesting that similar numeracy skills and similar speed-accuracy settings are involved in the four tasks. In the model, accuracy is related to drift rate and RT is related to speed-accuracy criteria, but drift rate and criteria are not related to each other across subjects. This provides a theoretical basis for understanding why negative correlations were not obtained between accuracy and RT. We also manipulated criteria by instructing subjects to maximize either speed or accuracy, but still found correlations between the criteria settings between and within tasks, suggesting that the settings may represent an individual trait that can be modulated but not equated across subjects. Our results demonstrate that a decision-making model may provide a way to reconcile inconsistent and sometimes contradictory results in numeracy

  4. A mixture hierarchical model for response times and response accuracy.

    PubMed

    Wang, Chun; Xu, Gongjun

    2015-11-01

    In real testing, examinees may manifest different types of test-taking behaviours. In this paper we focus on two types that appear to be among the more frequently occurring behaviours – solution behaviour and rapid guessing behaviour. Rapid guessing usually happens in high-stakes tests when there is insufficient time, and in low-stakes tests when there is lack of effort. These two qualitatively different test-taking behaviours, if ignored, will lead to violation of the local independence assumption and, as a result, yield biased item/person parameter estimation. We propose a mixture hierarchical model to account for differences among item responses and response time patterns arising from these two behaviours. The model is also able to identify the specific behaviour an examinee engages in when answering an item. A Monte Carlo expectation maximization algorithm is proposed for model calibration. A simulation study shows that the new model yields more accurate item and person parameter estimates than a non-mixture model when the data indeed come from two types of behaviour. The model also fits real, high-stakes test data better than a non-mixture model, and therefore the new model can better identify the underlying test-taking behaviour an examinee engages in on a certain item.

  5. Posterior Predictive Checks for Conditional Independence between Response Time and Accuracy

    ERIC Educational Resources Information Center

    Bolsinova, Maria; Tijmstra, Jesper

    2016-01-01

    Conditional independence (CI) between response time and response accuracy is a fundamental assumption of many joint models for time and accuracy used in educational measurement. In this study, posterior predictive checks (PPCs) are proposed for testing this assumption. These PPCs are based on three discrepancy measures reflecting different…

  6. A Systematic Investigation of Accuracy and Response Time Based Measures Used to Index ANS Acuity

    PubMed Central

    Dietrich, Julia Felicitas; Huber, Stefan; Klein, Elise; Willmes, Klaus; Pixner, Silvia; Moeller, Korbinian

    2016-01-01

    The approximate number system (ANS) was proposed to be a building block for later mathematical abilities. Several measures have been used interchangeably to assess ANS acuity. Some of these measures were based on accuracy data, whereas others relied on response time (RT) data or combined accuracy and RT data. Previous studies challenged the view that all these measures can be used interchangeably, because low correlations between some of the measures had been observed. These low correlations might be due to poor reliability of some of the measures, since the majority of these measures are mathematically related. Here we systematically investigated the relationship between common ANS measures while avoiding the potential confound of poor reliability. Our first experiment revealed high correlations between all accuracy based measures supporting the assumption that all of them can be used interchangeably. In contrast, not all RT based measures were highly correlated. Additionally, our results revealed a speed-accuracy trade-off. Thus, accuracy and RT based measures provided conflicting conclusions regarding ANS acuity. Therefore, we investigated in two further experiments which type of measure (accuracy or RT) is more informative about the underlying ANS acuity, depending on participants’ preferences for accuracy or speed. To this end, we manipulated participants’ preferences for accuracy or speed both explicitly using different task instructions and implicitly varying presentation duration. Accuracy based measures were more informative about the underlying ANS acuity than RT based measures. Moreover, the influence of the underlying representations on accuracy data was more pronounced when participants preferred accuracy over speed after the accuracy instruction as well as for long or unlimited presentation durations. Implications regarding the diffusion model as a theoretical framework of dot comparison as well as regarding the relationship between ANS acuity and

  7. Presentation and response timing accuracy in Adobe Flash and HTML5/JavaScript Web experiments.

    PubMed

    Reimers, Stian; Stewart, Neil

    2015-06-01

    Web-based research is becoming ubiquitous in the behavioral sciences, facilitated by convenient, readily available participant pools and relatively straightforward ways of running experiments: most recently, through the development of the HTML5 standard. Although in most studies participants give untimed responses, there is a growing interest in being able to record response times online. Existing data on the accuracy and cross-machine variability of online timing measures are limited, and generally they have compared behavioral data gathered on the Web with similar data gathered in the lab. For this article, we took a more direct approach, examining two ways of running experiments online-Adobe Flash and HTML5 with CSS3 and JavaScript-across 19 different computer systems. We used specialist hardware to measure stimulus display durations and to generate precise response times to visual stimuli in order to assess measurement accuracy, examining effects of duration, browser, and system-to-system variability (such as across different Windows versions), as well as effects of processing power and graphics capability. We found that (a) Flash and JavaScript's presentation and response time measurement accuracy are similar; (b) within-system variability is generally small, even in low-powered machines under high load; (c) the variability of measured response times across systems is somewhat larger; and (d) browser type and system hardware appear to have relatively small effects on measured response times. Modeling of the effects of this technical variability suggests that for most within- and between-subjects experiments, Flash and JavaScript can both be used to accurately detect differences in response times across conditions. Concerns are, however, noted about using some correlational or longitudinal designs online.

  8. A phase transition model for the speed-accuracy trade-off in response time experiments.

    PubMed

    Dutilh, Gilles; Wagenmakers, Eric-Jan; Visser, Ingmar; van der Maas, Han L J

    2011-03-01

    Most models of response time (RT) in elementary cognitive tasks implicitly assume that the speed-accuracy trade-off is continuous: When payoffs or instructions gradually increase the level of speed stress, people are assumed to gradually sacrifice response accuracy in exchange for gradual increases in response speed. This trade-off presumably operates over the entire range from accurate but slow responding to fast but chance-level responding (i.e., guessing). In this article, we challenge the assumption of continuity and propose a phase transition model for RTs and accuracy. Analogous to the fast guess model (Ollman, 1966), our model postulates two modes of processing: a guess mode and a stimulus-controlled mode. From catastrophe theory, we derive two important predictions that allow us to test our model against the fast guess model and against the popular class of sequential sampling models. The first prediction--hysteresis in the transitions between guessing and stimulus-controlled behavior--was confirmed in an experiment that gradually changed the reward for speed versus accuracy. The second prediction--bimodal RT distributions--was confirmed in an experiment that required participants to respond in a way that is intermediate between guessing and accurate responding.

  9. Accuracy and response time comparisons of four skin temperature-monitoring devices.

    PubMed

    Krause, B F

    1993-06-01

    Although technological improvements in skin surface temperature-measurement devices have progressed since they were first used clinically, the question of their accuracy and reliability for skin temperature monitoring still remains. The purpose of this study was to compare the accuracy and response time to temperature change for four temperature-monitoring devices: liquid crystal (Crystaline ST, Sharn, Inc, Tampa, Fla), two different thermistor sensors (RSP, Respiratory Support Products, Inc, Irvine, Calif, and SHER-I-TEMP, Sheridan Catheter Corp, Argyle, NY), and one thermocouple-based temperature sensor (Mon-a-therm, Mallinckrodt, Inc, St. Louis, Mo). A temperature-controlled steel surface plate was used as the reference temperature source for test comparisons. The results showed that Crystaline ST (liquid crystal device) performed better in the accuracy and response time tests than the electronic thermistor and thermocouple temperature-sensor devices tested. Regression analysis of the reference temperature comparisons showed that although all four devices had high correlation coefficients Crystaline ST had the highest correlation (R = 0.99685). Also, the regression equation for Crystaline ST was closest to a perfect fit with reference temperatures, ie, slope = 1.00267 and intercept = 0.20333 (P = .0000). Crystaline ST responded consistently faster than the other devices for each change in temperature setting (5, 10, 15, and 20 degrees F). Crystaline ST responded within 3.5 to 4.4 seconds for every temperature gradient change tested. All three of the other sensor devices had increasingly longer response times as the temperature gradient increased.(ABSTRACT TRUNCATED AT 250 WORDS)

  10. The Effects of Caffeine on Arousal, Response Time, Accuracy, and Performance in Division I Collegiate Fencers.

    PubMed

    Doyle, Taylor P; Lutz, Rafer S; Pellegrino, Joseph K; Sanders, David J; Arent, Shawn M

    2016-11-01

    Doyle, TP, Lutz, RS, Pellegrino, JK, Sanders, DJ, and Arent, SM. The effects of caffeine on arousal, response time, accuracy, and performance in Division I collegiate fencers. J Strength Cond Res 30(11): 3228-3235, 2016-Caffeine has displayed ergogenic effects on aerobic performance. However, sports requiring precision and quick reaction may also be impacted by central nervous system arousal because of caffeine consumption. The purpose of this study was to assess the effects of caffeine on arousal, response time (RT), and accuracy during a simulated fencing practice. Using a randomized, within-subjects, placebo-controlled, double-blind design, Division I male and female college fencers (N = 13; 69.1 ± 3.5 kg) were administered caffeine doses of 0, 1.5, 3.0, 4.5, 6.0, or 7.5 mg·kg during separate testing days. Performance was assessed via RT and accuracy to a 4-choice reaction task. A total of 25 trials were performed each day using a random 2- to 8-s delay between trials. Arousal was assessed using the activation-deactivation adjective check list. Results of repeated-measures multivariate analysis of variance revealed a significant dose effect (p = 0.02) on performance. Follow-up analyses indicated this was due to a significant effect for RT (p = 0.03), with the dose-response curve exhibiting a quadratic relationship. Response time was significantly faster (p < 0.01) for the 1.5, 3.0, and 6.0 mg·kg conditions than for the placebo condition. Results also indicated a significant dose effect for composite RT + accuracy performance (p < 0.01). The dose-response curve was again quadratic, with performance beginning to deteriorate at 7.5 mg·kg. Energetic arousal, tiredness, tension, and calmness all significantly changed as a function of caffeine dose (p ≤ 0.05). Based on these results, caffeine improves RT and overall performance in fencers, particularly as doses increase up to 4.5-6.0 mg·kg. Above this level, performance begins to deteriorate, consistent with an

  11. A PC parallel port button box provides millisecond response time accuracy under Linux.

    PubMed

    Stewart, Neil

    2006-02-01

    For psychologists, it is sometimes necessary to measure people's reaction times to the nearest millisecond. This article describes how to use the PC parallel port to receive signals from a button box to achieve millisecond response time accuracy. The workings of the parallel port, the corresponding port addresses, and a simple Linux program for controlling the port are described. A test of the speed and reliability of button box signal detection is reported. If the reader is moderately familiar with Linux, this article should provide sufficient instruction for him or her to build and test his or her own parallel port button box. This article also describes how the parallel port could be used to control an external apparatus.

  12. An Accuracy--Response Time Capacity Assessment Function that Measures Performance against Standard Parallel Predictions

    ERIC Educational Resources Information Center

    Townsend, James T.; Altieri, Nicholas

    2012-01-01

    Measures of human efficiency under increases in mental workload or attentional limitations are vital in studying human perception, cognition, and action. Assays of efficiency as workload changes have typically been confined to either reaction times (RTs) or accuracy alone. Within the realm of RTs, a nonparametric measure called the "workload…

  13. A Semiparametric Model for Jointly Analyzing Response Times and Accuracy in Computerized Testing

    ERIC Educational Resources Information Center

    Wang, Chun; Fan, Zhewen; Chang, Hua-Hua; Douglas, Jeffrey A.

    2013-01-01

    The item response times (RTs) collected from computerized testing represent an underutilized type of information about items and examinees. In addition to knowing the examinees' responses to each item, we can investigate the amount of time examinees spend on each item. Current models for RTs mainly focus on parametric models, which have the…

  14. Conditional Dependence between Response Time and Accuracy: An Overview of its Possible Sources and Directions for Distinguishing between Them

    PubMed Central

    Bolsinova, Maria; Tijmstra, Jesper; Molenaar, Dylan; De Boeck, Paul

    2017-01-01

    With the widespread use of computerized tests in educational measurement and cognitive psychology, registration of response times has become feasible in many applications. Considering these response times helps provide a more complete picture of the performance and characteristics of persons beyond what is available based on response accuracy alone. Statistical models such as the hierarchical model (van der Linden, 2007) have been proposed that jointly model response time and accuracy. However, these models make restrictive assumptions about the response processes (RPs) that may not be realistic in practice, such as the assumption that the association between response time and accuracy is fully explained by taking speed and ability into account (conditional independence). Assuming conditional independence forces one to ignore that many relevant individual differences may play a role in the RPs beyond overall speed and ability. In this paper, we critically consider the assumption of conditional independence and the important ways in which it may be violated in practice from a substantive perspective. We consider both conditional dependences that may arise when all persons attempt to solve the items in similar ways (homogeneous RPs) and those that may be due to persons differing in fundamental ways in how they deal with the items (heterogeneous processes). The paper provides an overview of what we can learn from observed conditional dependences. We argue that explaining and modeling these differences in the RPs is crucial to increase both the validity of measurement and our understanding of the relevant RPs. PMID:28261136

  15. Constant versus variable response signal delays in speed--accuracy trade-offs: effects of advance preparation for processing time.

    PubMed

    Miller, Jeff; Sproesser, Gudrun; Ulrich, Rolf

    2008-07-01

    In two experiments, we used response signals (RSs) to control processing time and trace out speed--accuracy trade-off(SAT) functions in a difficult perceptual discrimination task. Each experiment compared performance in blocks of trials with constant and, hence, temporally predictable RS lags against performance in blocks with variable, unpredictable RS lags. In both experiments, essentially equivalent SAT functions were observed with constant and variable RS lags. We conclude that there is little effect of advance preparation for a given processing time, suggesting that the discrimination mechanisms underlying SAT functions are driven solely by bottom-up information processing in perceptual discrimination tasks.

  16. High Accuracy Time Transfer Synchronization

    DTIC Science & Technology

    1994-12-01

    HIGH ACCURACY TIME TRANSFER SYNCHRONIZATION Paul Wheeler, Paul Koppang, David Chalmers, Angela Davis, Anthony Kubik and William Powell U.S. Naval...Observatory Washington, DC 20392 Abstract In July 1994, the US Naval Observatory (USNO) Time Service System Engineering Division conducted a...field test to establish a baseline accuracy for two-way satellite time transfer synchro- nization. Three Hewlett-Packard model 5071 high performance

  17. High accuracy time transfer synchronization

    NASA Technical Reports Server (NTRS)

    Wheeler, Paul J.; Koppang, Paul A.; Chalmers, David; Davis, Angela; Kubik, Anthony; Powell, William M.

    1995-01-01

    In July 1994, the U.S. Naval Observatory (USNO) Time Service System Engineering Division conducted a field test to establish a baseline accuracy for two-way satellite time transfer synchronization. Three Hewlett-Packard model 5071 high performance cesium frequency standards were transported from the USNO in Washington, DC to Los Angeles, California in the USNO's mobile earth station. Two-Way Satellite Time Transfer links between the mobile earth station and the USNO were conducted each day of the trip, using the Naval Research Laboratory(NRL) designed spread spectrum modem, built by Allen Osborne Associates(AOA). A Motorola six channel GPS receiver was used to track the location and altitude of the mobile earth station and to provide coordinates for calculating Sagnac corrections for the two-way measurements, and relativistic corrections for the cesium clocks. This paper will discuss the trip, the measurement systems used and the results from the data collected. We will show the accuracy of using two-way satellite time transfer for synchronization and the performance of the three HP 5071 cesium clocks in an operational environment.

  18. Brief report: accuracy and response time for the recognition of facial emotions in a large sample of children with autism spectrum disorders.

    PubMed

    Fink, Elian; de Rosnay, Marc; Wierda, Marlies; Koot, Hans M; Begeer, Sander

    2014-09-01

    The empirical literature has presented inconsistent evidence for deficits in the recognition of basic emotion expressions in children with autism spectrum disorders (ASD), which may be due to the focus on research with relatively small sample sizes. Additionally, it is proposed that although children with ASD may correctly identify emotion expression they rely on more deliberate, more time-consuming strategies in order to accurately recognize emotion expressions when compared to typically developing children. In the current study, we examine both emotion recognition accuracy and response time in a large sample of children, and explore the moderating influence of verbal ability on these findings. The sample consisted of 86 children with ASD (M age = 10.65) and 114 typically developing children (M age = 10.32) between 7 and 13 years of age. All children completed a pre-test (emotion word-word matching), and test phase consisting of basic emotion recognition, whereby they were required to match a target emotion expression to the correct emotion word; accuracy and response time were recorded. Verbal IQ was controlled for in the analyses. We found no evidence of a systematic deficit in emotion recognition accuracy or response time for children with ASD, controlling for verbal ability. However, when controlling for children's accuracy in word-word matching, children with ASD had significantly lower emotion recognition accuracy when compared to typically developing children. The findings suggest that the social impairments observed in children with ASD are not the result of marked deficits in basic emotion recognition accuracy or longer response times. However, children with ASD may be relying on other perceptual skills (such as advanced word-word matching) to complete emotion recognition tasks at a similar level as typically developing children.

  19. Effects of Age and Task Load on Drivers’ Response Accuracy and Reaction Time When Responding to Traffic Lights

    PubMed Central

    Salvia, Emilie; Petit, Claire; Champely, Stéphane; Chomette, René; Di Rienzo, Franck; Collet, Christian

    2016-01-01

    Due to population aging, elderly drivers represent an increasing proportion of car drivers. Yet, how aging alters sensorimotor functions and impacts driving safety remains poorly understood. This paper aimed at assessing to which extent elderly drivers are sensitive to various task loads and how this affects the reaction time (RT) in a driving context. Old and middle-aged people completed RT tasks which reproduced cognitive demands encountered while driving. Participants had to detect and respond to traffic lights or traffic light arrows as quickly as possible, under three experimental conditions of incremental difficulty. In both groups, we hypothesized that decision-making would be impacted by the number of cues to be processed. The first test was a simple measure of RT. The second and third tests were choice RT tasks requiring the processing of 3 and 5 cues, respectively. Responses were collected within a 2 s time-window. Otherwise, the trial was considered a no-response. In both groups, the data revealed that RT, error rate (incorrect answers), and no-response rate increased along with task difficulty. However, the middle-aged group outperformed the elderly group. The RT difference between the two groups increased drastically along with task difficulty. In the third test, the rate of no-response suggested that elderly drivers needed more than 2 s to process complex information and respond accurately. Both prolonged RT and increased no-response rate, especially for difficult tasks, might attest an impairment of cognitive abilities in relation to aging. Accordingly, casual driving conditions for young drivers may be particularly complex and stressful for elderly people who should thus be informed about the effects of normal aging upon driving. PMID:27462266

  20. Time and position accuracy using codeless GPS

    NASA Technical Reports Server (NTRS)

    Dunn, C. E.; Jefferson, D. C.; Lichten, S. M.; Thomas, J. B.; Vigue, Y.; Young, L. E.

    1994-01-01

    The Global Positioning System has allowed scientists and engineers to make measurements having accuracy far beyond the original 15 meter goal of the system. Using global networks of P-Code capable receivers and extensive post-processing, geodesists have achieved baseline precision of a few parts per billion, and clock offsets have been measured at the nanosecond level over intercontinental distances. A cloud hangs over this picture, however. The Department of Defense plans to encrypt the P-Code (called Anti-Spoofing, or AS) in the fall of 1993. After this event, geodetic and time measurements will have to be made using codeless GPS receivers. However, there appears to be a silver lining to the cloud. In response to the anticipated encryption of the P-Code, the geodetic and GPS receiver community has developed some remarkably effective means of coping with AS without classified information. We will discuss various codeless techniques currently available and the data noise resulting from each. We will review some geodetic results obtained using only codeless data, and discuss the implications for time measurements. Finally, we will present the status of GPS research at JPL in relation to codeless clock measurements.

  1. Accuracy metrics for judging time scale algorithms

    NASA Technical Reports Server (NTRS)

    Douglas, R. J.; Boulanger, J.-S.; Jacques, C.

    1994-01-01

    Time scales have been constructed in different ways to meet the many demands placed upon them for time accuracy, frequency accuracy, long-term stability, and robustness. Usually, no single time scale is optimum for all purposes. In the context of the impending availability of high-accuracy intermittently-operated cesium fountains, we reconsider the question of evaluating the accuracy of time scales which use an algorithm to span interruptions of the primary standard. We consider a broad class of calibration algorithms that can be evaluated and compared quantitatively for their accuracy in the presence of frequency drift and a full noise model (a mixture of white PM, flicker PM, white FM, flicker FM, and random walk FM noise). We present the analytic techniques for computing the standard uncertainty for the full noise model and this class of calibration algorithms. The simplest algorithm is evaluated to find the average-frequency uncertainty arising from the noise of the cesium fountain's local oscillator and from the noise of a hydrogen maser transfer-standard. This algorithm and known noise sources are shown to permit interlaboratory frequency transfer with a standard uncertainty of less than 10(exp -15) for periods of 30-100 days.

  2. Psychometric Modeling of Response Speed and Accuracy with Mixed and Conditional Regression

    ERIC Educational Resources Information Center

    Van Breukelen, Gerard J. P.

    2005-01-01

    Human performance in cognitive testing and experimental psychology is expressed in terms of response speed and accuracy. Data analysis is often limited to either speed or accuracy, and/or to crude summary measures like mean response time (RT) or the percentage correct responses. This paper proposes the use of mixed regression for the psychometric…

  3. Speed accuracy trade-off under response deadlines

    PubMed Central

    Karşılar, Hakan; Simen, Patrick; Papadakis, Samantha; Balcı, Fuat

    2014-01-01

    Perceptual decision making has been successfully modeled as a process of evidence accumulation up to a threshold. In order to maximize the rewards earned for correct responses in tasks with response deadlines, participants should collapse decision thresholds dynamically during each trial so that a decision is reached before the deadline. This strategy ensures on-time responding, though at the cost of reduced accuracy, since slower decisions are based on lower thresholds and less net evidence later in a trial (compared to a constant threshold). Frazier and Yu (2008) showed that the normative rate of threshold reduction depends on deadline delays and on participants' uncertainty about these delays. Participants should start collapsing decision thresholds earlier when making decisions under shorter deadlines (for a given level of timing uncertainty) or when timing uncertainty is higher (for a given deadline). We tested these predictions using human participants in a random dot motion discrimination task. Each participant was tested in free-response, short deadline (800 ms), and long deadline conditions (1000 ms). Contrary to optimal-performance predictions, the resulting empirical function relating accuracy to response time (RT) in deadline conditions did not decline to chance level near the deadline; nor did the slight decline we typically observed relate to measures of endogenous timing uncertainty. Further, although this function did decline slightly with increasing RT, the decline was explainable by the best-fitting parameterization of Ratcliff's diffusion model (Ratcliff, 1978), whose parameters are constant within trials. Our findings suggest that at the very least, typical decision durations are too short for participants to adapt decision parameters within trials. PMID:25177265

  4. Acoustic environmental accuracy requirements for response determination

    NASA Technical Reports Server (NTRS)

    Pettitt, M. R.

    1983-01-01

    A general purpose computer program was developed for the prediction of vehicle interior noise. This program, named VIN, has both modal and statistical energy analysis capabilities for structural/acoustic interaction analysis. The analytic models and their computer implementation were verified through simple test cases with well-defined experimental results. The model was also applied in a space shuttle payload bay launch acoustics prediction study. The computer program processes large and small problems with equal efficiency because all arrays are dynamically sized by program input variables at run time. A data base is built and easily accessed for design studies. The data base significantly reduces the computational costs of such studies by allowing the reuse of the still-valid calculated parameters of previous iterations.

  5. Spontaneous Fluctuations in Visual Cortical Responses Influence Population Coding Accuracy.

    PubMed

    Gutnisky, Diego A; Beaman, Charles B; Lew, Sergio E; Dragoi, Valentin

    2017-02-01

    Information processing in the cerebral cortex depends not only on the nature of incoming stimuli, but also on the state of neuronal networks at the time of stimulation. That is, the same stimulus will be processed differently depending on the neuronal context in which it is received. A major factor that could influence neuronal context is the background, or ongoing neuronal activity before stimulation. In visual cortex, ongoing activity is known to play a critical role in the development of local circuits, yet whether it influences the coding of visual features in adult cortex is unclear. Here, we investigate whether and how the information encoded by individual neurons and populations in primary visual cortex (V1) depends on the ongoing activity before stimulus presentation. We report that when individual neurons are in a "low" prestimulus state, they have a higher capacity to discriminate stimulus features, such as orientation, despite their reduction in evoked responses. By measuring the distribution of prestimulus activity across a population of neurons, we found that network discrimination accuracy is improved in the low prestimulus state. Thus, the distribution of ongoing activity states across the network creates an "internal context" that dynamically filters incoming stimuli to modulate the accuracy of sensory coding. The modulation of stimulus coding by ongoing activity state is consistent with recurrent network models in which ongoing activity dynamically controls the balanced background excitation and inhibition to individual neurons.

  6. Accuracy of Pedometer Steps and Time for Youth with Disabilities

    ERIC Educational Resources Information Center

    Beets, Michael W.; Combs, Cindy; Pitetti, Kenneth H.; Morgan, Melinda; Bryan, Rebecca R.; Foley, John T.

    2007-01-01

    The purpose of the study was to examine the accuracy of pedometer steps and activity time (Walk4Life, WL) for youth with developmental disabilities. Eighteen youth (11 girls, 7 boys) 4-14 years completed six 80-meter self-paced walking trials while wearing a pedometer at five waist locations (front right, front left, back right, back left, middle…

  7. A Measurement Model for Likert Responses that Incorporates Response Time

    ERIC Educational Resources Information Center

    Ferrando, Pere J.; Lorenzo-Seva, Urbano

    2007-01-01

    This article describes a model for response times that is proposed as a supplement to the usual factor-analytic model for responses to graded or more continuous typical-response items. The use of the proposed model together with the factor model provides additional information about the respondent and can potentially increase the accuracy of the…

  8. Assessing expected accuracy of probe vehicle travel time reports

    SciTech Connect

    Hellinga, B.; Fu, L.

    1999-12-01

    The use of probe vehicles to provide estimates of link travel times has been suggested as a means of obtaining travel times within signalized networks for use in advanced travel information systems. Past research in the literature has proved contradictory conclusions regarding the expected accuracy of these probe-based estimates, and consequently has estimated different levels of market penetration of probe vehicles required to sustain accurate data within an advanced traveler information system. This paper examines the effect of sampling bias on the accuracy of the probe estimates. An analytical expression is derived on the basis of queuing theory to prove that bias in arrival time distributions and/or in the proportion of probes associated with each link departure turning movement will lead to a systematic bias in the sample estimate of the mean delay. Subsequently, the potential for and impact of sampling bias on a signalized link is examined by simulating an arterial corridor. The analytical derivation and the simulation analysis show that the reliability of probe-based average link travel times is highly affected by sampling bias. Furthermore, this analysis shows that the contradictory conclusions of previous research are directly related to the presence of absence of sample bias.

  9. Improving Adaptive Learning Technology through the Use of Response Times

    ERIC Educational Resources Information Center

    Mettler, Everett; Massey, Christine M.; Kellman, Philip J.

    2011-01-01

    Adaptive learning techniques have typically scheduled practice using learners' accuracy and item presentation history. We describe an adaptive learning system (Adaptive Response Time Based Sequencing--ARTS) that uses both accuracy and response time (RT) as direct inputs into sequencing. Response times are used to assess learning strength and…

  10. Assessment of the accuracy and stability of ENSN sensors responses

    NASA Astrophysics Data System (ADS)

    Nofal, Hamed; Mohamed, Omar; Mohanna, Mahmoud; El-Gabry, Mohamed

    2015-06-01

    The Egyptian National Seismic Network (ENSN) is an advanced scientific tool used to investigate earth structure and seismic activity in Egypt. One of the main tasks of the engineering team of ENSN is to keep the accuracy and stability of the high performance seismic instruments as close as possible to the international standards used in international seismic network. To achieve this task, the seismometers are routinely calibrated. One of the final outcomes of the calibration process is a set of the actual poles and zeros of the seismometers. Due to the strategic importance of the High Dam, we present in this paper the results of the calibrating broad band (BB) seismometers type Trillium-40 (40 second). From these sets we computed both amplitude and phase responses as well as their deviations from the nominal responses of this particular seismometer type. The computed deviation of this sub-network is then statistically analyzed to obtain an overall estimate of the accuracy of measurements recorded by it. Such analysis might also discover some stations which are far from the international standards. This test will be carried out regularly at periods of several months to find out how stable the seismometer response is. As a result, the values of the magnitude and phase errors are confined between 0% and 2% for about 90% of the calibrated seismometers. The average magnitude error was found to be 5% from the nominal and 4% for average phase error. In order to eliminate any possible error in the measured data, the measured (true) poles and zeroes are used in the response files to replace the nominal values.

  11. The effect of speed-accuracy strategy on response interference control in Parkinson's disease.

    PubMed

    Wylie, S A; van den Wildenberg, W P M; Ridderinkhof, K R; Bashore, T R; Powell, V D; Manning, C A; Wooten, G F

    2009-07-01

    Studies that used conflict paradigms such as the Eriksen Flanker task show that many individuals with Parkinson's disease (PD) have pronounced difficulty resolving the conflict that arises from the simultaneous activation of mutually exclusive responses. This finding fits well with contemporary views that postulate a key role for the basal ganglia in action selection. The present experiment aims to specify the cognitive processes that underlie action selection deficits among PD patients in the context of variations in speed-accuracy strategy. PD patients (n=28) and healthy controls (n=17) performed an arrow version of the flanker task under task instructions that either emphasized speed or accuracy of responses. Reaction time (RT) and accuracy rates decreased with speed compared to accuracy instructions, although to a lesser extent for the PD group. Differences in flanker interference effects among PD and healthy controls depended on speed-accuracy strategy. Compared to the healthy controls, PD patients showed larger flanker interference effects under speed stress. RT distribution analyses suggested that PD patients have greater difficulty suppressing incorrect response activation when pressing for speed. These initial findings point to an important interaction between strategic and computational aspects of interference control in accounting for cognitive impairments of PD. The results are also compatible with recent brain imaging studies that demonstrate basal ganglia activity to co-vary with speed-accuracy adjustments.

  12. Time-resolved spectral imaging: better photon economy, higher accuracy

    NASA Astrophysics Data System (ADS)

    Fereidouni, Farzad; Reitsma, Keimpe; Blab, Gerhard A.; Gerritsen, Hans C.

    2015-03-01

    Lifetime and spectral imaging are complementary techniques that offer a non-invasive solution for monitoring metabolic processes, identifying biochemical compounds, and characterizing their interactions in biological tissues, among other tasks. Newly developed instruments that perform time-resolved spectral imaging can provide even more information and reach higher sensitivity than either modality alone. Here we report a multispectral lifetime imaging system based on a field-programmable gate array (FPGA), capable of operating at high photon count rates (12 MHz) per spectral detection channel, and with time resolution of 200 ps. We performed error analyses to investigate the effect of gate width and spectral-channel width on the accuracy of estimated lifetimes and spectral widths. Temporal and spectral phasors were used for analysis of recorded data, and we demonstrated blind un-mixing of the fluorescent components using information from both modalities. Fractional intensities, spectra, and decay curves of components were extracted without need for prior information. We further tested this approach with fluorescently doubly-labeled DNA, and demonstrated its suitability for accurately estimating FRET efficiency in the presence of either non-interacting or interacting donor molecules.

  13. Inertial Measures of Motion for Clinical Biomechanics: Comparative Assessment of Accuracy under Controlled Conditions – Changes in Accuracy over Time

    PubMed Central

    Lebel, Karina; Boissy, Patrick; Hamel, Mathieu; Duval, Christian

    2015-01-01

    Background Interest in 3D inertial motion tracking devices (AHRS) has been growing rapidly among the biomechanical community. Although the convenience of such tracking devices seems to open a whole new world of possibilities for evaluation in clinical biomechanics, its limitations haven’t been extensively documented. The objectives of this study are: 1) to assess the change in absolute and relative accuracy of multiple units of 3 commercially available AHRS over time; and 2) to identify different sources of errors affecting AHRS accuracy and to document how they may affect the measurements over time. Methods This study used an instrumented Gimbal table on which AHRS modules were carefully attached and put through a series of velocity-controlled sustained motions including 2 minutes motion trials (2MT) and 12 minutes multiple dynamic phases motion trials (12MDP). Absolute accuracy was assessed by comparison of the AHRS orientation measurements to those of an optical gold standard. Relative accuracy was evaluated using the variation in relative orientation between modules during the trials. Findings Both absolute and relative accuracy decreased over time during 2MT. 12MDP trials showed a significant decrease in accuracy over multiple phases, but accuracy could be enhanced significantly by resetting the reference point and/or compensating for initial Inertial frame estimation reference for each phase. Interpretation The variation in AHRS accuracy observed between the different systems and with time can be attributed in part to the dynamic estimation error, but also and foremost, to the ability of AHRS units to locate the same Inertial frame. Conclusions Mean accuracies obtained under the Gimbal table sustained conditions of motion suggest that AHRS are promising tools for clinical mobility assessment under constrained conditions of use. However, improvement in magnetic compensation and alignment between AHRS modules are desirable in order for AHRS to reach their

  14. Modeling Reaction Time and Accuracy of Multiple-Alternative Decisions

    PubMed Central

    Leite, Fábio P.; Ratcliff, Roger

    2009-01-01

    Several sequential sampling models using racing diffusion processes for multiple-alternative decisions were evaluated using data from two perceptual discrimination experiments. The structures of the models differed on a number of dimensions, including whether there was lateral inhibition between accumulators, whether there was decay in evidence, whether evidence could be negative, and whether there was variability in starting points. Data were collected from a letter discrimination task in which stimulus difficulty and probability of the response alternatives were varied along with number of response alternatives. Model fitting results ruled out a large number of model classes in favor of a smaller number of specific models, most of which showed a moderate to high degree of mimicking. The best-fitting models had zero to moderate values of decay, no inhibition, and assumed that the addition of alternatives either affected the subprocesses contributing to the nondecisional time, the degree of caution, or the quality of evidence extracted from stimuli. PMID:20045893

  15. Diagnostic accuracy of the bronchodilator response in children

    PubMed Central

    Tse, Sze Man; Gold, Diane R.; Sordillo, Joanne E.; Hoffman, Elaine B.; Gillman, Matthew W.; Rifas-Shiman, Sheryl L.; Fuhlbrigge, Anne L.; Tantisira, Kelan G.; Weiss, Scott T.; Litonjua, Augusto A.

    2013-01-01

    Background The bronchodilator response (BDR) reflects the reversibility of airflow obstruction and is recommended as an adjunctive test to diagnose asthma. The validity of the commonly used definition of BDR, a 12% or greater change in FEV1 from baseline, has been questioned in childhood. Objectives We sought to examine the diagnostic accuracy of the BDR test by using 3 large pediatric cohorts. Methods Cases include 1041 children with mild-to-moderate asthma from the Childhood Asthma Management Program. Control subjects (nonasthmatic and nonwheezing) were chosen from Project Viva and Home Allergens, 2 population-based pediatric cohorts. Receiver operating characteristic curves were constructed, and areas under the curve were calculated for different BDR cutoffs. Results A total of 1041 cases (59.7% male; mean age, 8.9 ± 2.1 years) and 250 control subjects (46.8% male; mean age, 8.7 ± 1.7 years) were analyzed, with mean BDRs of 10.7% ± 10.2% and 2.7% ± 8.4%, respectively. The BDR test differentiated asthmatic patients from nonasthmatic patients with a moderate accuracy (area under the curve, 73.3%). Despite good specificity, a cutoff of 12% was associated with poor sensitivity (35.6%). A cutoff of less than 8% performed significantly better than a cutoff of 12% (P = .03, 8% vs 12%). Conclusions Our findings highlight the poor sensitivity associated with the commonly used 12% cutoff for BDR. Although our data show that a threshold of less than 8% performs better than 12%, given the variability of this test in children, we conclude that it might be not be appropriate to choose a specific BDR cutoff as a criterion for the diagnosis of asthma. PMID:23683464

  16. Modeling Response Signal and Response Time Data

    ERIC Educational Resources Information Center

    Ratcliff, Roger

    2006-01-01

    The diffusion model (Ratcliff, 1978) and the leaky competing accumulator model (LCA, Usher & McClelland, 2001) were tested against two-choice data collected from the same subjects with the standard response time procedure and the response signal procedure. In the response signal procedure, a stimulus is presented and then, at one of a number of…

  17. Pulse transit time measured by photoplethysmography improves the accuracy of heart rate as a surrogate measure of cardiac output, stroke volume and oxygen uptake in response to graded exercise.

    PubMed

    Pollonini, L; Padhye, N S; Re, R; Torricelli, A; Simpson, R J; Dacso, C C

    2015-05-01

    Heart rate (HR) is a valuable and widespread measure for physical training programs, although its description of conditioning is limited to the cardiac response to exercise. More comprehensive measures of exercise adaptation include cardiac output (Q̇), stroke volume (SV) and oxygen uptake (V̇O2), but these physiological parameters can be measured only with cumbersome equipment installed in clinical settings. In this work, we explore the ability of pulse transit time (PTT) to represent a valuable pairing with HR for indirectly estimating Q̇, SV and V̇O2 non-invasively. PTT was measured as the time interval between the peak of the electrocardiographic (ECG) R-wave and the onset of the photoplethysmography (PPG) waveform at the periphery (i.e. fingertip) with a portable sensor. Fifteen healthy young subjects underwent a graded incremental cycling protocol after which HR and PTT were correlated with Q̇, SV and V̇O2 using linear mixed models. The addition of PTT significantly improved the modeling of Q̇, SV and V̇O2 at the individual level ([Formula: see text] for SV, 0.548 for Q̇, and 0.771 for V̇O2) compared to predictive models based solely on HR ([Formula: see text] for SV, 0.503 for Q̇, and 0.745 for V̇O2). While challenges in sensitivity and artifact rejection exist, combining PTT with HR holds potential for development of novel wearable sensors that provide exercise assessment largely superior to HR monitors.

  18. Post awakening salivary cortisol secretion and trait well-being: The importance of sample timing accuracy.

    PubMed

    Smyth, Nina; Thorn, Lisa; Hucklebridge, Frank; Evans, Phil; Clow, Angela

    2015-08-01

    Indices of post awakening cortisol secretion (PACS), include the rise in cortisol (cortisol awakening response: CAR) and overall cortisol concentrations (e.g., area under the curve with reference to ground: AUCg) in the first 30-45 min. Both are commonly investigated in relation to psychosocial variables. Although sampling within the domestic setting is ecologically valid, participant non-adherence to the required timing protocol results in erroneous measurement of PACS and this may explain discrepancies in the literature linking these measures to trait well-being (TWB). We have previously shown that delays of little over 5 min (between awakening and the start of sampling) to result in erroneous CAR estimates. In this study, we report for the first time on the negative impact of sample timing inaccuracy (verified by electronic-monitoring) on the efficacy to detect significant relationships between PACS and TWB when measured in the domestic setting. Healthy females (N=49, 20.5±2.8 years) selected for differences in TWB collected saliva samples (S1-4) on 4 days at 0, 15, 30, 45 min post awakening, to determine PACS. Adherence to the sampling protocol was objectively monitored using a combination of electronic estimates of awakening (actigraphy) and sampling times (track caps). Relationships between PACS and TWB were found to depend on sample timing accuracy. Lower TWB was associated with higher post awakening cortisol AUCg in proportion to the mean sample timing accuracy (p<.005). There was no association between TWB and the CAR even taking into account sample timing accuracy. These results highlight the importance of careful electronic monitoring of participant adherence for measurement of PACS in the domestic setting. Mean sample timing inaccuracy, mainly associated with delays of >5 min between awakening and collection of sample 1 (median=8 min delay), negatively impacts on the sensitivity of analysis to detect associations between PACS and TWB.

  19. Effects of Interviewer Behavior on Accuracy of Children's Responses

    ERIC Educational Resources Information Center

    Sparling, Jessica; Wilder, David A.; Kondash, Jennifer; Boyle, Megan; Compton, Megan

    2011-01-01

    Previous research has shown that certain interviewer behaviors can evoke inaccurate answers by children. In the current study, we examined the effects of approving and disapproving statements on the accuracy of 3 children's answers to questions in an interview (Experiment 1). We then evaluated 3 questioning techniques that may be used by…

  20. Advantages of improved timing accuracy in PET cameras using LSOscintillator

    SciTech Connect

    Moses, William W.

    2002-12-02

    PET scanners based on LSO have the potential forsignificantly better coincidence timing resolution than the 6 ns fwhmtypically achieved with BGO. This study analyzes the performanceenhancements made possible by improved timing as a function of thecoincidence time resolution. If 500 ps fwhm coincidence timing resolutioncan be achieved in a complete PET camera, the following four benefits canbe realized for whole-body FDG imaging: 1) The random event rate can bereduced by using a narrower coincidence timing window, increasing thepeak NECR by~;50 percent. 2) Using time-of-flight in the reconstructionalgorithm will reduce the noise variance by a factor of 5. 3) Emissionand transmission data can be acquired simultaneously, reducing the totalscan time. 4) Axial blurring can be reduced by using time-of-flight todetermine the correct axial plane that each event originated from. Whiletime-of-flight was extensively studied in the 1980's, practical factorslimited its effectiveness at that time and little attention has been paidto timing in PET since then. As these potential improvements aresubstantial and the advent of LSO PET cameras gives us the means toobtain them without other sacrifices, efforts to improve PET timingshould resume after their long dormancy.

  1. An Evaluation of Item Response Theory Classification Accuracy and Consistency Indices

    ERIC Educational Resources Information Center

    Wyse, Adam E.; Hao, Shiqi

    2012-01-01

    This article introduces two new classification consistency indices that can be used when item response theory (IRT) models have been applied. The new indices are shown to be related to Rudner's classification accuracy index and Guo's classification accuracy index. The Rudner- and Guo-based classification accuracy and consistency indices are…

  2. Accuracy in Recalling Interest Inventory Information at Three Time Intervals

    ERIC Educational Resources Information Center

    Swanson, Jane L.; Gore, Paul A., Jr.; Leuwerke, Wade; D'Achiardi, Catalina; Edwards, Jorie Hitch; Edwards, Jared

    2006-01-01

    Rates of accurate recall of the Strong Interest Inventory (SII; L. W. Harmon, J. C. Hansen, F. H. Borgen, & A. L. Hammer, 1994) profile information varied with the amount of time elapsed since the interpretation, the type of SII scale, and whether immediate recall was elicited, but rates did not vary with the strategy used to provide the…

  3. Is Empathic Accuracy Enough to Facilitate Responsive Behavior in Dyadic Interaction? Distinguishing Ability From Motivation.

    PubMed

    Winczewski, Lauren A; Bowen, Jeffrey D; Collins, Nancy L

    2016-03-01

    Growing evidence suggests that interpersonal responsiveness-feeling understood, validated, and cared for by other people-plays a key role in shaping the quality of one's social interactions and relationships. But what enables people to be interpersonally responsive to others? In the current study, we argued that responsiveness requires not only accurate understanding but also compassionate motivation. Specifically, we hypothesized that understanding another person's thoughts and feelings (empathic accuracy) would foster responsive behavior only when paired with benevolent motivation (empathic concern). To test this idea, we asked couples (N = 91) to discuss a personal or relationship stressor; we then assessed empathic accuracy, empathic concern, and responsive behavior. As predicted, when listeners' empathic concern was high, empathic accuracy facilitated responsiveness; but when empathic concern was low, empathic accuracy was unhelpful (and possibly harmful) for responsiveness. These findings provide the first evidence that cognitive and affective forms of empathy work together to facilitate responsive behavior.

  4. Real time hybrid simulation with online model updating: An analysis of accuracy

    NASA Astrophysics Data System (ADS)

    Ou, Ge; Dyke, Shirley J.; Prakash, Arun

    2017-02-01

    In conventional hybrid simulation (HS) and real time hybrid simulation (RTHS) applications, the information exchanged between the experimental substructure and numerical substructure is typically restricted to the interface boundary conditions (force, displacement, acceleration, etc.). With additional demands being placed on RTHS and recent advances in recursive system identification techniques, an opportunity arises to improve the fidelity by extracting information from the experimental substructure. Online model updating algorithms enable the numerical model of components (herein named the target model), that are similar to the physical specimen to be modified accordingly. This manuscript demonstrates the power of integrating a model updating algorithm into RTHS (RTHSMU) and explores the possible challenges of this approach through a practical simulation. Two Bouc-Wen models with varying levels of complexity are used as target models to validate the concept and evaluate the performance of this approach. The constrained unscented Kalman filter (CUKF) is selected for using in the model updating algorithm. The accuracy of RTHSMU is evaluated through an estimation output error indicator, a model updating output error indicator, and a system identification error indicator. The results illustrate that, under applicable constraints, by integrating model updating into RTHS, the global response accuracy can be improved when the target model is unknown. A discussion on model updating parameter sensitivity to updating accuracy is also presented to provide guidance for potential users.

  5. Real-time lens distortion correction: speed, accuracy and efficiency

    NASA Astrophysics Data System (ADS)

    Bax, Michael R.; Shahidi, Ramin

    2014-11-01

    Optical lens systems suffer from nonlinear geometrical distortion. Optical imaging applications such as image-enhanced endoscopy and image-based bronchoscope tracking require correction of this distortion for accurate localization, tracking, registration, and measurement of image features. Real-time capability is desirable for interactive systems and live video. The use of a texture-mapping graphics accelerator, which is standard hardware on current motherboard chipsets and add-in video graphics cards, to perform distortion correction is proposed. Mesh generation for image tessellation, an error analysis, and performance results are presented. It is shown that distortion correction using commodity graphics hardware is substantially faster than using the main processor and can be performed at video frame rates (faster than 30 frames per second), and that the polar-based method of mesh generation proposed here is more accurate than a conventional grid-based approach. Using graphics hardware to perform distortion correction is not only fast and accurate but also efficient as it frees the main processor for other tasks, which is an important issue in some real-time applications.

  6. A Joint Modeling Approach for Reaction Time and Accuracy in Psycholinguistic Experiments

    ERIC Educational Resources Information Center

    Loeys, T.; Rosseel, Y.; Baten, K.

    2011-01-01

    In the psycholinguistic literature, reaction times and accuracy can be analyzed separately using mixed (logistic) effects models with crossed random effects for item and subject. Given the potential correlation between these two outcomes, a joint model for the reaction time and accuracy may provide further insight. In this paper, a Bayesian…

  7. EFFECTS OF INTERVIEWER BEHAVIOR ON ACCURACY OF CHILDREN'S RESPONSES

    PubMed Central

    Sparling, Jessica; Wilder, David A; Kondash, Jennifer; Boyle, Megan; Compton, Megan

    2011-01-01

    Previous research has shown that certain interviewer behaviors can evoke inaccurate answers by children. In the current study, we examined the effects of approving and disapproving statements on the accuracy of 3 children's answers to questions in an interview (Experiment 1). We then evaluated 3 questioning techniques that may be used by interviewers during a forensic interview in which a child provides eyewitness testimony (Experiment 2). All participants responded with more inaccurate answers when approving statements followed inaccurate information and disapproving statements followed accurate information in Experiment 1. During Experiment 2, 1 participant responded most inaccurately when she was requestioned after providing an initial answer, whereas the remaining 2 participants responded most inaccurately when the interviewer provided cowitness information and suggestive questions. PMID:21941387

  8. Verification of concentration time formulae accuracy in Southern Brazil

    NASA Astrophysics Data System (ADS)

    Freitas Ferreira, Pedro; Allasia, Daniel; Herbstrith Froemming, Gabriel; Ribeiro Fontoura, Jessica; Tassi, Rutineia

    2016-04-01

    The time of concentration (TC) of an urban catchment is a fundamental watershed parameter used to compute the peak discharge and/or in the hydrological simulation of sewer systems. In the lack of hydrological data for its estimative, several empirical formulae are used, however, almost none of them have been verified in Brazil leading to large uncertainties in the correct value. In this light, were tested several formulae such as the proposed by Kirpich (and a modifications of this equation proposed by the National Transport Bureau of Brazil (DNIT)), U.S. Corps. Of Engineers, Pasini, Dooge , Johnstone , Ventura and Ven T Chow as they are used in Brazil. The verification was accomplished against measured data in 5 sub-basins situated in the Dilúvio basin, a semi urbanized watershed that contains the most developed area of the city of Porto Alegre. All the rainfall stations were active in the period from late 1970's until early 1980's due to the existence of Projeto Dilúvio but today, however, only two of them are still in operation. Porto Alegre is the capital and largest city in the Brazilian southernmost state of Rio Grande do Sul with a population of approximately 1.6 million inhabitants, the tenth most populous city in the country and the centre of Brazil's fourth largest metropolitan area, with almost 4,5 million inhabitants (IBGE, 2010). The city is situated in a humid subtropical climate with high and regular precipitation throughout the year. Most summer rainfall occurs during thunderstorms and an occasional tropical storm, hurricane or cyclone. The results showed an error of around 70% for half of the formulas, with a tendency to underestimate TC values. Among the tested methods, Johnstone had the best overall result, with an average error of 25%, well far from the second, Dooge, with 43% of average error. The best results were obtained in only one basin, Dilúvio, the largest one, with an area of 25km², with an error of just 3% for Modified Kirpich, and

  9. Accuracy of time comparison derived from reception of LORAN-C and Global Positioning System time signals

    NASA Astrophysics Data System (ADS)

    Horiai, Koji

    1992-10-01

    The accuracy of time comparison by means of the reception of common time signals, namely, LORAN-C and Global Positioning System (GPS), is examined. Differences of UTC from the emission times of these two radio wave signals measured at four Japanese stations and one U.S. station are analyzed and compared with the clock comparison reports published by the Bureau International des Poids et Mesures. The accuracy of the time comparison via LORAN-C signals of the northwest Pacific chain is about 3.61 microns and that via GPS is 0.14 microns. The accuracy analysis reveals the existence of systematic errors at the individual stations. In LORAN-C, the most serious error comes from those in the delay time calibration of receiving instruments and estimation of the propagation delay over land. Calibration of the clocks by a portable clock improves the accuracy of the GPS method to the accuracy of the GPS signals.

  10. Estimation Accuracy on Execution Time of Run-Time Tasks in a Heterogeneous Distributed Environment

    PubMed Central

    Liu, Qi; Cai, Weidong; Jin, Dandan; Shen, Jian; Fu, Zhangjie; Liu, Xiaodong; Linge, Nigel

    2016-01-01

    Distributed Computing has achieved tremendous development since cloud computing was proposed in 2006, and played a vital role promoting rapid growth of data collecting and analysis models, e.g., Internet of things, Cyber-Physical Systems, Big Data Analytics, etc. Hadoop has become a data convergence platform for sensor networks. As one of the core components, MapReduce facilitates allocating, processing and mining of collected large-scale data, where speculative execution strategies help solve straggler problems. However, there is still no efficient solution for accurate estimation on execution time of run-time tasks, which can affect task allocation and distribution in MapReduce. In this paper, task execution data have been collected and employed for the estimation. A two-phase regression (TPR) method is proposed to predict the finishing time of each task accurately. Detailed data of each task have drawn interests with detailed analysis report being made. According to the results, the prediction accuracy of concurrent tasks’ execution time can be improved, in particular for some regular jobs. PMID:27589753

  11. Estimation Accuracy on Execution Time of Run-Time Tasks in a Heterogeneous Distributed Environment.

    PubMed

    Liu, Qi; Cai, Weidong; Jin, Dandan; Shen, Jian; Fu, Zhangjie; Liu, Xiaodong; Linge, Nigel

    2016-08-30

    Distributed Computing has achieved tremendous development since cloud computing was proposed in 2006, and played a vital role promoting rapid growth of data collecting and analysis models, e.g., Internet of things, Cyber-Physical Systems, Big Data Analytics, etc. Hadoop has become a data convergence platform for sensor networks. As one of the core components, MapReduce facilitates allocating, processing and mining of collected large-scale data, where speculative execution strategies help solve straggler problems. However, there is still no efficient solution for accurate estimation on execution time of run-time tasks, which can affect task allocation and distribution in MapReduce. In this paper, task execution data have been collected and employed for the estimation. A two-phase regression (TPR) method is proposed to predict the finishing time of each task accurately. Detailed data of each task have drawn interests with detailed analysis report being made. According to the results, the prediction accuracy of concurrent tasks' execution time can be improved, in particular for some regular jobs.

  12. Response accuracy of hazard identification in migrant farm workers.

    PubMed

    Burau, Keith D; Shipp, Eva M; Cooper, Sharon P; Frankowski, Ralph; McKinnon, Sarah; Walker, Kristina M

    2006-01-01

    This study assessed potential biases introduced by using maternal proxies for reporting work hazards, illness symptoms, and acute agricultural injuries in studies of migrant farmworker families. A convenience sample of 79 mother/spouse and mother/oldest child pairs was obtained from a two-year cohort study of migrant farmworker families from Starr County, Texas. Pairs completed an interviewer-administered survey including 27 close-ended items describing work history, illness symptoms, and acute injuries during the 2001 migration season. Data analysis included prevalence, sensitivity, and specificity measures. Maternal proxy reports of subjective symptoms of a spouse or child were approximately 50% lower than spouse or child self-reports. Sensitivity and specificity of mothers' responses regarding hazard items were higher for spouses than for children. For items measuring illness symptoms, sensitivity of mothers' responses for spouses and oldest child pairs was generally less than 30%; however, specificity was generally above 90%. For acute agricultural injury, the mother/spouse sensitivity was 75%, the mother/child 40%, and specificities were 100% and 97%, respectively. Sensitivity and specificity for mother/ spouse pairs was generally higher than mother/child pairs for work hazards, illness symptoms and acute injuries. While mothers may be acceptable proxies for spouses in this population, efforts should be made to collect data directly from adolescent children in studies of agricultural injuries.

  13. Understanding less than nothing: children's neural response to negative numbers shifts across age and accuracy.

    PubMed

    Gullick, Margaret M; Wolford, George

    2013-01-01

    We examined the brain activity underlying the development of our understanding of negative numbers, which are amounts lacking direct physical counterparts. Children performed a paired comparison task with positive and negative numbers during an fMRI session. As previously shown in adults, both pre-instruction fifth-graders and post-instruction seventh-graders demonstrated typical behavioral and neural distance effects to negative numbers, where response times and parietal and frontal activity increased as comparison distance decreased. We then determined the factors impacting the distance effect in each age group. Behaviorally, the fifth-grader distance effect for negatives was significantly predicted only by positive comparison accuracy, indicating that children who were generally better at working with numbers were better at comparing negatives. In seventh-graders, negative number comparison accuracy significantly predicted their negative number distance effect, indicating that children who were better at working with negative numbers demonstrated a more typical distance effect. Across children, as age increased, the negative number distance effect increased in the bilateral IPS and decreased frontally, indicating a frontoparietal shift consistent with previous numerical development literature. In contrast, as negative comparison task accuracy increased, the parietal distance effect increased in the left IPS and decreased in the right, possibly indicating a change from an approximate understanding of negatives' values to a more exact, precise representation (particularly supported by the left IPS) with increasing expertise. These shifts separately indicate the effects of increasing maturity generally in numeric processing and specifically in negative number understanding.

  14. High-accuracy global time and frequency transfer with a space-borne hydrogen maser clock

    NASA Technical Reports Server (NTRS)

    Decher, R.; Allan, D. W.; Alley, C. O.; Baugher, C.; Duncan, B. J.; Vessot, R. F. C.; Winkler, G. M. R.

    1983-01-01

    A proposed system for high-accuracy global time and frequency transfer using a hydrogen maser clock in a space vehicle is discussed. Direct frequency transfer with a accuracy of 10 to the minus 14th power and time transfer with an estimated accuracy of 1 nsec are provided by a 3-link microwave system. A short pulse laser system is included for subnanosecond time transfer and system calibration. The results of studies including operational aspects, error sources, data flow, system configuration, and implementation requirements for an initial demonstration experiment using the Space Shuttle are discussed.

  15. Accuracy of time comparison derived from reception of LORAN-C and Global Positioning System time signals.

    NASA Astrophysics Data System (ADS)

    Horiai, K.

    1992-10-01

    The accuracy of time comparison by means of the reception of common time signals, namely, LORAN-C and GPS, is examined. Differences of UTC from the emission times of these two radio wave signals measured at four Japanese stations and one US station are analyzed and compared with the clock comparison reports published by the Bureau International des Poids et Mesures. The accuracy of the time comparison via LORAN-C signals of the northwest Pacific chain is about 3.61 μs and that via GPS is 0.14 μs.

  16. Continuous theta burst stimulation over the left pre-motor cortex affects sensorimotor timing accuracy and supraliminal error correction.

    PubMed

    Bijsterbosch, Janine D; Lee, Kwang-Hyuk; Dyson-Sutton, William; Barker, Anthony T; Woodruff, Peter W R

    2011-09-02

    Adjustments to movement in response to changes in our surroundings are common in everyday behavior. Previous research has suggested that the left pre-motor cortex (PMC) is specialized for the temporal control of movement and may play a role in temporal error correction. The aim of this study was to determine the role of the left PMC in sensorimotor timing and error correction using theta burst transcranial magnetic stimulation (TBS). In Experiment 1, subjects performed a sensorimotor synchronization task (SMS) with the left and the right hand before and after either continuous or intermittent TBS (cTBS or iTBS). Timing accuracy was assessed during synchronized finger tapping with a regular auditory pacing stimulus. Responses following perceivable local timing shifts in the pacing stimulus (phase shifts) were used to measure error correction. Suppression of the left PMC using cTBS decreased timing accuracy because subjects tapped further away from the pacing tones and tapping variability increased. In addition, error correction responses returned to baseline tap-tone asynchrony levels faster following negative shifts and no overcorrection occurred following positive shifts after cTBS. However, facilitation of the left PMC using iTBS did not affect timing accuracy or error correction performance. Experiment 2 revealed that error correction performance may change with practice, independent of TBS. These findings provide evidence for a role of the left PMC in both sensorimotor timing and error correction in both hands. We propose that the left PMC may be involved in voluntarily controlled phase correction responses to perceivable timing shifts.

  17. Accuracy of time comparison derived from reception of LORAN-C and Global Positioning System time signals.

    NASA Astrophysics Data System (ADS)

    Horiai, K.

    1992-10-01

    The accuracy of time comparison by means of the reception of common time signals, namely, LORAN-C and Global Positioning System (GPS), is examined. Differences of UTC from the emission times of these two radio wave signals measured at four Japanese stations and one U.S. station are analyzed and compared with the clock comparison reports published by the Bureau International des Poids et Mesures. The accuracy of the time comparison via LORAN-C signals of the northwest Pacific chain is about 3.61 μs and that via GPS is 0.14 μs. The accuracy analysis reveals the existence of systematic errors at the individual stations. In LORAN-C, the most serious error comes from those in the delay time calibration of receiving instruments and estimation of the propagation delay over land. Calibration of the clocks by a portable clock improves the accuracy of the GPS method to the accuracy of the GPS signals.

  18. Studies of the accuracy of time integration methods for reaction-diffusion equations

    NASA Astrophysics Data System (ADS)

    Ropp, David L.; Shadid, John N.; Ober, Curtis C.

    2004-03-01

    In this study we present numerical experiments of time integration methods applied to systems of reaction-diffusion equations. Our main interest is in evaluating the relative accuracy and asymptotic order of accuracy of the methods on problems which exhibit an approximate balance between the competing component time scales. Nearly balanced systems can produce a significant coupling of the physical mechanisms and introduce a slow dynamical time scale of interest. These problems provide a challenging test for this evaluation and tend to reveal subtle differences between the various methods. The methods we consider include first- and second-order semi-implicit, fully implicit, and operator-splitting techniques. The test problems include a prototype propagating nonlinear reaction-diffusion wave, a non-equilibrium radiation-diffusion system, a Brusselator chemical dynamics system and a blow-up example. In this evaluation we demonstrate a "split personality" for the operator-splitting methods that we consider. While operator-splitting methods often obtain very good accuracy, they can also manifest a serious degradation in accuracy due to stability problems.

  19. An Effective Approach to Improving Low-Cost GPS Positioning Accuracy in Real-Time Navigation

    PubMed Central

    Islam, Md. Rashedul; Kim, Jong-Myon

    2014-01-01

    Positioning accuracy is a challenging issue for location-based applications using a low-cost global positioning system (GPS). This paper presents an effective approach to improving the positioning accuracy of a low-cost GPS receiver for real-time navigation. The proposed method precisely estimates position by combining vehicle movement direction, velocity averaging, and distance between waypoints using coordinate data (latitude, longitude, time, and velocity) of the GPS receiver. The previously estimated precious reference point, coordinate translation, and invalid data check also improve accuracy. In order to evaluate the performance of the proposed method, we conducted an experiment using a GARMIN GPS 19xHVS receiver attached to a car and used Google Maps to plot the processed data. The proposed method achieved improvement of 4–10 meters in several experiments. In addition, we compared the proposed approach with two other state-of-the-art methods: recursive averaging and ARMA interpolation. The experimental results show that the proposed approach outperforms other state-of-the-art methods in terms of positioning accuracy. PMID:25136679

  20. Minimal Plasma Response Models for Design of Tokamak Equilibrium Controllers with High Dynamic Accuracy

    NASA Astrophysics Data System (ADS)

    Humphreys, D. A.; Walker, M. L.; Leuer, J. A.

    1999-11-01

    We describe a model of linearized plasma shape and position response which is based on low poloidal mode number (m<=2, approximately vertical and major radial) displacements of the plasma current distribution. The model introduces minimal plasma degrees of freedom while providing sufficient accuracy for high performance controller design. The effects of significant variation in plasma poloidal beta, internal inductance, and separatrix configuration are taken into account. Models which can predict plasma shape and position variation with reasonable accuracy are particularly important for design of dynamic controllers in devices with significant variation in auxiliary heating input power and plasma shape --- conditions common in the DIII--D tokamak. Model predictions are validated using experimental response data from DIII--D. Application of the plasma response model to design of multivariable dynamic plasma controllers recently implemented on DIII--D is described.

  1. Accuracy of EMS-Reported Last Known Normal Times in Suspected Acute Stroke Patients

    PubMed Central

    Curfman, David; Connor, Lisa Tabor; Moy, Hawnwan Philip; Heitsch, Laura; Panagos, Peter; Lee, Jin-Moo; Tan, David K.; Ford, Andria L.

    2014-01-01

    Background and Purpose The last known normal (LKN) time is a critical determinant of IV tPA eligibility; however, the accuracy of EMS-reported LKN times is unknown. We determined the congruence between EMS-reported and neurologist-determined LKN times and identified predictors of incongruent LKN times. Methods We prospectively collected EMS-reported LKN times for patients brought into the ED with suspected acute stroke and calculated the absolute difference between the EMS-reported and neurologist-determined LKN times (|ΔLKN|). We determined the rate of inappropriate IV tPA use if EMS-reported times had been used in place of neurologist-determined times. Univariate and multivariable linear regression assessed for any predictors of prolonged |ΔLKN|. Results Of 251 patients, mean and median |ΔLKN| were 28 and 0 minutes, respectively. |ΔLKN| was <15 min in 91% of the entire cohort and was <15 min in 80% of patients with a diagnosis of stroke (n=86). Of patients who received IV tPA, none would have been incorrectly excluded from IV tPA if the EMS LKN time had been used. Conversely, of patients who did not receive IV tPA, 6% would have been incorrectly included for IV tPA consideration had the EMS time been used. In patients with wake-up stroke symptoms, EMS underestimated LKN times: mean EMS LKN time - neurologist LKN time = −208 minutes. The presence of wake-up stroke symptoms (p<0.0001) and older age (p=0.019) were independent predictors of prolonged |ΔLKN|. Conclusions EMS-reported LKN times were largely congruent with neurologist-determined times. Focused EMS training regarding wake-up stroke symptoms may further improve accuracy. PMID:24643409

  2. Testing the accuracy of timing reports in visual timing tasks with a consumer-grade digital camera.

    PubMed

    Smyth, Rachael E; Oram Cardy, Janis; Purcell, David

    2016-06-20

    This study tested the accuracy of a visual timing task using a readily available and relatively inexpensive consumer grade digital camera. A visual inspection time task was recorded using short high-speed video clips and the timing as reported by the task's program was compared to the timing as recorded in the video clips. Discrepancies in these two timing reports were investigated further and based on display refresh rate, a decision was made whether the discrepancy was large enough to affect the results as reported by the task. In this particular study, the errors in timing were not large enough to impact the results of the study. The procedure presented in this article offers an alternative method for performing a timing test, which uses readily available hardware and can be used to test the timing in any software program on any operating system and display.

  3. Accuracy of Pedometer Steps and Time for Youth with Intellectual Disabilities during Dynamic Movements

    ERIC Educational Resources Information Center

    Pitetti, Kenneth H.; Beets, Michael W.; Flaming, Judy

    2009-01-01

    Pedometer accuracy for steps and activity time during dynamic movement for youth with intellectual disabilities (ID) were examined. Twenty-four youth with ID (13 girls, 13.1 [plus or minus] 3.2 yrs; 11 boys, 14.7 [plus or minus] 2.7 yrs) were videotaped during adapted physical education class while wearing a Walk4Life 2505 pedometer in five…

  4. Accuracy and responses of genomic selection on key traits in apple breeding

    PubMed Central

    Muranty, Hélène; Troggio, Michela; Sadok, Inès Ben; Rifaï, Mehdi Al; Auwerkerken, Annemarie; Banchi, Elisa; Velasco, Riccardo; Stevanato, Piergiorgio; van de Weg, W Eric; Di Guardo, Mario; Kumar, Satish; Laurens, François; Bink, Marco C A M

    2015-01-01

    The application of genomic selection in fruit tree crops is expected to enhance breeding efficiency by increasing prediction accuracy, increasing selection intensity and decreasing generation interval. The objectives of this study were to assess the accuracy of prediction and selection response in commercial apple breeding programmes for key traits. The training population comprised 977 individuals derived from 20 pedigreed full-sib families. Historic phenotypic data were available on 10 traits related to productivity and fruit external appearance and genotypic data for 7829 SNPs obtained with an Illumina 20K SNP array. From these data, a genome-wide prediction model was built and subsequently used to calculate genomic breeding values of five application full-sib families. The application families had genotypes at 364 SNPs from a dedicated 512 SNP array, and these genotypic data were extended to the high-density level by imputation. These five families were phenotyped for 1 year and their phenotypes were compared to the predicted breeding values. Accuracy of genomic prediction across the 10 traits reached a maximum value of 0.5 and had a median value of 0.19. The accuracies were strongly affected by the phenotypic distribution and heritability of traits. In the largest family, significant selection response was observed for traits with high heritability and symmetric phenotypic distribution. Traits that showed non-significant response often had reduced and skewed phenotypic variation or low heritability. Among the five application families the accuracies were uncorrelated to the degree of relatedness to the training population. The results underline the potential of genomic prediction to accelerate breeding progress in outbred fruit tree crops that still need to overcome long generation intervals and extensive phenotyping costs. PMID:26744627

  5. A new accuracy measure based on bounded relative error for time series forecasting

    PubMed Central

    Twycross, Jamie; Garibaldi, Jonathan M.

    2017-01-01

    Many accuracy measures have been proposed in the past for time series forecasting comparisons. However, many of these measures suffer from one or more issues such as poor resistance to outliers and scale dependence. In this paper, while summarising commonly used accuracy measures, a special review is made on the symmetric mean absolute percentage error. Moreover, a new accuracy measure called the Unscaled Mean Bounded Relative Absolute Error (UMBRAE), which combines the best features of various alternative measures, is proposed to address the common issues of existing measures. A comparative evaluation on the proposed and related measures has been made with both synthetic and real-world data. The results indicate that the proposed measure, with user selectable benchmark, performs as well as or better than other measures on selected criteria. Though it has been commonly accepted that there is no single best accuracy measure, we suggest that UMBRAE could be a good choice to evaluate forecasting methods, especially for cases where measures based on geometric mean of relative errors, such as the geometric mean relative absolute error, are preferred. PMID:28339480

  6. A new accuracy measure based on bounded relative error for time series forecasting.

    PubMed

    Chen, Chao; Twycross, Jamie; Garibaldi, Jonathan M

    2017-01-01

    Many accuracy measures have been proposed in the past for time series forecasting comparisons. However, many of these measures suffer from one or more issues such as poor resistance to outliers and scale dependence. In this paper, while summarising commonly used accuracy measures, a special review is made on the symmetric mean absolute percentage error. Moreover, a new accuracy measure called the Unscaled Mean Bounded Relative Absolute Error (UMBRAE), which combines the best features of various alternative measures, is proposed to address the common issues of existing measures. A comparative evaluation on the proposed and related measures has been made with both synthetic and real-world data. The results indicate that the proposed measure, with user selectable benchmark, performs as well as or better than other measures on selected criteria. Though it has been commonly accepted that there is no single best accuracy measure, we suggest that UMBRAE could be a good choice to evaluate forecasting methods, especially for cases where measures based on geometric mean of relative errors, such as the geometric mean relative absolute error, are preferred.

  7. Travel-time source-specific station correction improves location accuracy

    NASA Astrophysics Data System (ADS)

    Giuntini, Alessandra; Materni, Valerio; Chiappini, Stefano; Carluccio, Roberto; Console, Rodolfo; Chiappini, Massimo

    2013-04-01

    Accurate earthquake locations are crucial for investigating seismogenic processes, as well as for applications like verifying compliance to the Comprehensive Test Ban Treaty (CTBT). Earthquake location accuracy is related to the degree of knowledge about the 3-D structure of seismic wave velocity in the Earth. It is well known that modeling errors of calculated travel times may have the effect of shifting the computed epicenters far from the real locations by a distance even larger than the size of the statistical error ellipses, regardless of the accuracy in picking seismic phase arrivals. The consequences of large mislocations of seismic events in the context of the CTBT verification is particularly critical in order to trigger a possible On Site Inspection (OSI). In fact, the Treaty establishes that an OSI area cannot be larger than 1000 km2, and its larger linear dimension cannot be larger than 50 km. Moreover, depth accuracy is crucial for the application of the depth event screening criterion. In the present study, we develop a method of source-specific travel times corrections based on a set of well located events recorded by dense national seismic networks in seismically active regions. The applications concern seismic sequences recorded in Japan, Iran and Italy. We show that mislocations of the order of 10-20 km affecting the epicenters, as well as larger mislocations in hypocentral depths, calculated from a global seismic network and using the standard IASPEI91 travel times can be effectively removed by applying source-specific station corrections.

  8. Accuracy and time requirements of a bar-code inventory system for medical supplies.

    PubMed

    Hanson, L B; Weinswig, M H; De Muth, J E

    1988-02-01

    The effects of implementing a bar-code system for issuing medical supplies to nursing units at a university teaching hospital were evaluated. Data on the time required to issue medical supplies to three nursing units at a 480-bed, tertiary-care teaching hospital were collected (1) before the bar-code system was implemented (i.e., when the manual system was in use), (2) one month after implementation, and (3) four months after implementation. At the same times, the accuracy of the central supply perpetual inventory was monitored using 15 selected items. One-way analysis of variance tests were done to determine any significant differences between the bar-code and manual systems. Using the bar-code system took longer than using the manual system because of a significant difference in the time required for order entry into the computer. Multiple-use requirements of the central supply computer system made entering bar-code data a much slower process. There was, however, a significant improvement in the accuracy of the perpetual inventory. Using the bar-code system for issuing medical supplies to the nursing units takes longer than using the manual system. However, the accuracy of the perpetual inventory was significantly improved with the implementation of the bar-code system.

  9. Entropy of space-time outcome in a movement speed-accuracy task.

    PubMed

    Hsieh, Tsung-Yu; Pacheco, Matheus Maia; Newell, Karl M

    2015-12-01

    The experiment reported was set-up to investigate the space-time entropy of movement outcome as a function of a range of spatial (10, 20 and 30 cm) and temporal (250-2500 ms) criteria in a discrete aiming task. The variability and information entropy of the movement spatial and temporal errors considered separately increased and decreased on the respective dimension as a function of an increment of movement velocity. However, the joint space-time entropy was lowest when the relative contribution of spatial and temporal task criteria was comparable (i.e., mid-range of space-time constraints), and it increased with a greater trade-off between spatial or temporal task demands, revealing a U-shaped function across space-time task criteria. The traditional speed-accuracy functions of spatial error and temporal error considered independently mapped to this joint space-time U-shaped entropy function. The trade-off in movement tasks with joint space-time criteria is between spatial error and timing error, rather than movement speed and accuracy.

  10. Reaction time and movement duration influence on end point accuracy in a fast reaching task.

    PubMed

    Skurvidas, A; Mickevichiene, D; Cesnavichiene, V; Gutnik, B; Nash, D

    2012-01-01

    In labor and sport physiology a great deal of interest concerns the conceptual model of governance of both rapid and precise target-directed movements. Widely known in the theory of motor control, Fitts' paradigm determines the time of motion, calculated from the distance to the target and the diameter of the target. However this paradigm does not take into account the time of preparation for movement, which can have a significant impact on accuracy. In addition, the literature highlights little evidence of temporal and spatial asymmetry in the production of fast and accurate movements. The aim of our work was to investigate the influence of the duration of the preparatory phase (reaction time - T(R)) and duration of protractile motion of the arm (T(M)) on the speed and accuracy of movement. Also, the in-dividual asymmetry of the temporal characteristics and accuracy of performance of movements were studied. We measured three aspects of translational motion of the arm to the computerized target: reaction time (T(R), s), time of motion of the arm (T(M), s), and error in the achievement of the target (deltaL, mm). The group of participants consisted of 12 healthy, right-handed, untrained girls, each of whom completed 5 series of 10 discrete movements by each of the left and right arms. Mathematical analysis of the results revealed the existence of five models of performance. Each model was represented in the participant's performance with different probability. The combination of high speed and high precision when the arm moved towards the target was found only in model 5, which combines a long period of preparation for the movement (T(R)) and a short time of motion (T(M)). The probability of its occurrence in the untrained subjects was very low (2-3%). We suggest that it may be possible to develop special methods of training, geared towards the ability to increase the probability of appearance of this model. Asymmetry of motor action appeared clearly evident only in

  11. High accuracy position response calibration method for a micro-channel plate ion detector

    NASA Astrophysics Data System (ADS)

    Hong, R.; Leredde, A.; Bagdasarova, Y.; Fléchard, X.; García, A.; Müller, P.; Knecht, A.; Liénard, E.; Kossin, M.; Sternberg, M. G.; Swanson, H. E.; Zumwalt, D. W.

    2016-11-01

    We have developed a position response calibration method for a micro-channel plate (MCP) detector with a delay-line anode position readout scheme. Using an in situ calibration mask, an accuracy of 8 μm and a resolution of 85 μm (FWHM) have been achieved for MeV-scale α particles and ions with energies of ∼10 keV. At this level of accuracy, the difference between the MCP position responses to high-energy α particles and low-energy ions is significant. The improved performance of the MCP detector can find applications in many fields of AMO and nuclear physics. In our case, it helps reducing systematic uncertainties in a high-precision nuclear β-decay experiment.

  12. Accuracy of System Step Response Roll Magnitude Estimation from Central and Peripheral Visual Displays and Simulator Cockpit Motion

    NASA Technical Reports Server (NTRS)

    Hosman, R. J. A. W.; Vandervaart, J. C.

    1984-01-01

    An experiment to investigate visual roll attitude and roll rate perception is described. The experiment was also designed to assess the improvements of perception due to cockpit motion. After the onset of the motion, subjects were to make accurate and quick estimates of the final magnitude of the roll angle step response by pressing the appropriate button of a keyboard device. The differing time-histories of roll angle, roll rate and roll acceleration caused by a step response stimulate the different perception processes related the central visual field, peripheral visual field and vestibular organs in different, yet exactly known ways. Experiments with either of the visual displays or cockpit motion and some combinations of these were run to asses the roles of the different perception processes. Results show that the differences in response time are much more pronounced than the differences in perception accuracy.

  13. 28 CFR 542.18 - Response time.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 28 Judicial Administration 2 2013-07-01 2013-07-01 false Response time. 542.18 Section 542.18... REMEDY Administrative Remedy Program § 542.18 Response time. If accepted, a Request or Appeal is... later than the third calendar day after filing. If the time period for response to a Request or...

  14. 28 CFR 542.18 - Response time.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 28 Judicial Administration 2 2011-07-01 2011-07-01 false Response time. 542.18 Section 542.18... REMEDY Administrative Remedy Program § 542.18 Response time. If accepted, a Request or Appeal is... later than the third calendar day after filing. If the time period for response to a Request or...

  15. 28 CFR 542.18 - Response time.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 28 Judicial Administration 2 2012-07-01 2012-07-01 false Response time. 542.18 Section 542.18... REMEDY Administrative Remedy Program § 542.18 Response time. If accepted, a Request or Appeal is... later than the third calendar day after filing. If the time period for response to a Request or...

  16. 28 CFR 542.18 - Response time.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 28 Judicial Administration 2 2014-07-01 2014-07-01 false Response time. 542.18 Section 542.18... REMEDY Administrative Remedy Program § 542.18 Response time. If accepted, a Request or Appeal is... later than the third calendar day after filing. If the time period for response to a Request or...

  17. A simple method for improving the time-stepping accuracy in atmosphere and ocean models

    NASA Astrophysics Data System (ADS)

    Williams, P. D.

    2012-12-01

    In contemporary numerical simulations of the atmosphere and ocean, evidence suggests that time-stepping errors may be a significant component of total model error, on both weather and climate time-scales. This presentation will review the available evidence, and will then suggest a simple but effective method for substantially improving the time-stepping numerics at no extra computational expense. A common time-stepping method in atmosphere and ocean models is the leapfrog scheme combined with the Robert-Asselin (RA) filter. This method is used in the following models (and many more): ECHAM, MAECHAM, MM5, CAM, MESO-NH, HIRLAM, KMCM, LIMA, SPEEDY, IGCM, PUMA, COSMO, FSU-GSM, FSU-NRSM, NCEP-GFS, NCEP-RSM, NSEAM, NOGAPS, RAMS, and CCSR/NIES-AGCM. Although the RA filter controls the time-splitting instability, it also introduces non-physical damping and reduces the accuracy. This presentation proposes a simple modification to the RA filter, which has become known as the RAW filter (Williams 2009, 2011). When used in conjunction with the leapfrog scheme, the RAW filter eliminates the non-physical damping and increases the amplitude accuracy by two orders, yielding third-order accuracy. (The phase accuracy remains second-order.) The RAW filter can easily be incorporated into existing models, typically via the insertion of just a single line of code. Better simulations are obtained at no extra computational expense. Results will be shown from recent implementations of the RAW filter in various models, including SPEEDY and COSMO. For example, in SPEEDY, the skill of weather forecasts is found to be significantly improved. In particular, in tropical surface pressure predictions, five-day forecasts made using the RAW filter have approximately the same skill as four-day forecasts made using the RA filter (Amezcua, Kalnay & Williams 2011). These improvements are encouraging for the use of the RAW filter in other atmosphere and ocean models. References PD Williams (2009) A

  18. Evaluating Cognitive Theory: A Joint Modeling Approach Using Responses and Response Times

    ERIC Educational Resources Information Center

    Klein Entink, Rinke H.; Kuhn, Jorg-Tobias; Hornke, Lutz F.; Fox, Jean-Paul

    2009-01-01

    In current psychological research, the analysis of data from computer-based assessments or experiments is often confined to accuracy scores. Response times, although being an important source of additional information, are either neglected or analyzed separately. In this article, a new model is developed that allows the simultaneous analysis of…

  19. Non-parametric estimation of a time-dependent predictive accuracy curve.

    PubMed

    Saha-Chaudhuri, P; Heagerty, P J

    2013-01-01

    A major biomedical goal associated with evaluating a candidate biomarker or developing a predictive model score for event-time outcomes is to accurately distinguish between incident cases from the controls surviving beyond t throughout the entire study period. Extensions of standard binary classification measures like time-dependent sensitivity, specificity, and receiver operating characteristic (ROC) curves have been developed in this context (Heagerty, P. J., and others, 2000. Time-dependent ROC curves for censored survival data and a diagnostic marker. Biometrics 56, 337-344). We propose a direct, non-parametric method to estimate the time-dependent Area under the curve (AUC) which we refer to as the weighted mean rank (WMR) estimator. The proposed estimator performs well relative to the semi-parametric AUC curve estimator of Heagerty and Zheng (2005. Survival model predictive accuracy and ROC curves. Biometrics 61, 92-105). We establish the asymptotic properties of the proposed estimator and show that the accuracy of markers can be compared very simply using the difference in the WMR statistics. Estimators of pointwise standard errors are provided.

  20. Structural equation modeling for estimating the identification accuracy and detection time latency of English monosyllabic words

    NASA Astrophysics Data System (ADS)

    Takayanagi, Sumiko; Bernstein, Lynne E.; Auer, Edward T.

    2003-10-01

    Structural equation modeling (SEM) was used to examine the statistical structure among sets of experiential (word age of acquisition and subjective familiarity) and lexical similarity (lexical equivalence class size and neighborhood density) variables for word identification and reaction time latency tasks. Stimuli were 240 vocoded monosyllabic English words with reduced intelligibility and altered similarity relationships. Participants detected a target word following a prime and on every trial reported the prime. The identification accuracy was estimated by words and phonemes correct, and detection latency was estimated by trimmed and harmonic mean RTs. A parsimonious SEM was chosen in terms of the chi-square and model fit indices that determine whether the models adequately described the particular associations of variables/interfactor relationships. The variable/factor error variances were constrained to be uncorrelated with each other in order to evaluate effects independently. A bootstrapping technique indicated that the regression weights of the top-down and bottom-up factors were small, but they were significant in the model. The variance accounted for (VAF) by the model was 7.1% for identification accuracy, and 5.2% for RT latency. The model also indicated that RT latency was highly influenced by prime identification accuracy (15% VAF). [Work supported by NIH/NIDCD00695.

  1. Classification Accuracy of Mixed Format Tests: A Bi-Factor Item Response Theory Approach

    PubMed Central

    Wang, Wei; Drasgow, Fritz; Liu, Liwen

    2016-01-01

    Mixed format tests (e.g., a test consisting of multiple-choice [MC] items and constructed response [CR] items) have become increasingly popular. However, the latent structure of item pools consisting of the two formats is still equivocal. Moreover, the implications of this latent structure are unclear: For example, do constructed response items tap reasoning skills that cannot be assessed with multiple choice items? This study explored the dimensionality of mixed format tests by applying bi-factor models to 10 tests of various subjects from the College Board's Advanced Placement (AP) Program and compared the accuracy of scores based on the bi-factor analysis with scores derived from a unidimensional analysis. More importantly, this study focused on a practical and important question—classification accuracy of the overall grade on a mixed format test. Our findings revealed that the degree of multidimensionality resulting from the mixed item format varied from subject to subject, depending on the disattenuated correlation between scores from MC and CR subtests. Moreover, remarkably small decrements in classification accuracy were found for the unidimensional analysis when the disattenuated correlations exceeded 0.90. PMID:26973568

  2. Accuracy of the Timed Up and Go test for predicting sarcopenia in elderly hospitalized patients

    PubMed Central

    Martinez, Bruno Prata; Gomes, Isabela Barboza; de Oliveira, Carolina Santana; Ramos, Isis Resende; Rocha, Mônica Diniz Marques; Júnior, Luiz Alberto Forgiarini; Camelier, Fernanda Warken Rosa; Camelier, Aquiles Assunção

    2015-01-01

    OBJECTIVES: The ability of the Timed Up and Go test to predict sarcopenia has not been evaluated previously. The objective of this study was to evaluate the accuracy of the Timed Up and Go test for predicting sarcopenia in elderly hospitalized patients. METHODS: This cross-sectional study analyzed 68 elderly patients (≥60 years of age) in a private hospital in the city of Salvador-BA, Brazil, between the 1st and 5th day of hospitalization. The predictive variable was the Timed Up and Go test score, and the outcome of interest was the presence of sarcopenia (reduced muscle mass associated with a reduction in handgrip strength and/or weak physical performance in a 6-m gait-speed test). After the descriptive data analyses, the sensitivity, specificity and accuracy of a test using the predictive variable to predict the presence of sarcopenia were calculated. RESULTS: In total, 68 elderly individuals, with a mean age 70.4±7.7 years, were evaluated. The subjects had a Charlson Comorbidity Index score of 5.35±1.97. Most (64.7%) of the subjects had a clinical admission profile; the main reasons for hospitalization were cardiovascular disorders (22.1%), pneumonia (19.1%) and abdominal disorders (10.2%). The frequency of sarcopenia in the sample was 22.1%, and the mean length of time spent performing the Timed Up and Go test was 10.02±5.38 s. A time longer than or equal to a cutoff of 10.85 s on the Timed Up and Go test predicted sarcopenia with a sensitivity of 67% and a specificity of 88.7%. The accuracy of this cutoff for the Timed Up and Go test was good (0.80; IC=0.66-0.94; p=0.002). CONCLUSION: The Timed Up and Go test was shown to be a predictor of sarcopenia in elderly hospitalized patients. PMID:26039955

  3. Enhanced perceived responsibility decreases metamemory but not memory accuracy in obsessive-compulsive disorder (OCD).

    PubMed

    Moritz, S; Wahl, K; Zurowski, B; Jelinek, L; Hand, I; Fricke, S

    2007-09-01

    Mixed findings have been obtained in prior research with respect to the presence and severity of memory and metamemory deficits in obsessive-compulsive disorder (OCD). We tested the hypothesis that experimentally induced increments of subjective responsibility would lead to a disproportionately strong decline of memory confidence and enhanced response latencies in OCD while leaving memory accuracy unaffected. Twenty-eight OCD patients and 28 healthy controls were presented a computerized memory test framed with two different scenarios. In the neutral scenario, the participant was requested to imagine purchasing 15 items from a do-it-yourself store. In the recognition phase, the 15 needed items were presented along with 15 distractor items. The participant was asked to decide whether items were on his or her shopping list or not, graded by subjective confidence. In the responsibility scenario, the general experimental setup was analogous except that the participant now had to envision that he or she was a helper in a region recently struck by an earthquake, dispatched to provide 15 urgently needed goods from a nearby town. In line with prior work by our group, samples did not differ in either condition on memory accuracy in a subsequent recognition task. As hypothesized, OCD participants were less certain in their responses for the high responsibility condition than controls. Whereas patients and controls did not differ in their subjective estimates for memorized items, patients expressed stronger doubt that their earthquake mission was successful. The findings indicate that low memory confidence in OCD may only be elicited in situations where perceived responsibility is high and that patients may share higher performance standards ("good is not good enough") than controls when perceived responsibility is inflated.

  4. Evolution of perturbed dynamical systems: analytical computation with time independent accuracy

    NASA Astrophysics Data System (ADS)

    Gurzadyan, A. V.; Kocharyan, A. A.

    2016-12-01

    An analytical method for investigation of the evolution of dynamical systems with independent on time accuracy is developed for perturbed Hamiltonian systems. The error-free estimation using of computer algebra enables the application of the method to complex multi-dimensional Hamiltonian and dissipative systems. It also opens principal opportunities for the qualitative study of chaotic trajectories. The performance of the method is demonstrated on perturbed two-oscillator systems. It can be applied to various non-linear physical and astrophysical systems, e.g. to long-term planetary dynamics.

  5. Sex differences in accuracy and precision when judging time to arrival: data from two Internet studies.

    PubMed

    Sanders, Geoff; Sinclair, Kamila

    2011-12-01

    We report two Internet studies that investigated sex differences in the accuracy and precision of judging time to arrival. We used accuracy to mean the ability to match the actual time to arrival and precision to mean the consistency with which each participant made their judgments. Our task was presented as a computer game in which a toy UFO moved obliquely towards the participant through a virtual three-dimensional space on route to a docking station. The UFO disappeared before docking and participants pressed their space bar at the precise moment they thought the UFO would have docked. Study 1 showed it was possible to conduct quantitative studies of spatiotemporal judgments in virtual reality via the Internet and confirmed reports that men are more accurate because women underestimate, but found no difference in precision measured as intra-participant variation. Study 2 repeated Study 1 with five additional presentations of one condition to provide a better measure of precision. Again, men were more accurate than women but there were no sex differences in precision. However, within the coincidence-anticipation timing (CAT) literature, of those studies that report sex differences, a majority found that males are both more accurate and more precise than females. Noting that many CAT studies report no sex differences, we discuss appropriate interpretations of such null findings. While acknowledging that CAT performance may be influenced by experience we suggest that the sex difference may have originated among our ancestors with the evolutionary selection of men for hunting and women for gathering.

  6. Comprehensive Numerical Analysis of Finite Difference Time Domain Methods for Improving Optical Waveguide Sensor Accuracy

    PubMed Central

    Samak, M. Mosleh E. Abu; Bakar, A. Ashrif A.; Kashif, Muhammad; Zan, Mohd Saiful Dzulkifly

    2016-01-01

    This paper discusses numerical analysis methods for different geometrical features that have limited interval values for typically used sensor wavelengths. Compared with existing Finite Difference Time Domain (FDTD) methods, the alternating direction implicit (ADI)-FDTD method reduces the number of sub-steps by a factor of two to three, which represents a 33% time savings in each single run. The local one-dimensional (LOD)-FDTD method has similar numerical equation properties, which should be calculated as in the previous method. Generally, a small number of arithmetic processes, which result in a shorter simulation time, are desired. The alternating direction implicit technique can be considered a significant step forward for improving the efficiency of unconditionally stable FDTD schemes. This comparative study shows that the local one-dimensional method had minimum relative error ranges of less than 40% for analytical frequencies above 42.85 GHz, and the same accuracy was generated by both methods.

  7. Timing accuracy of Web experiments: a case study using the WebExp software package.

    PubMed

    Keller, Frank; Gunasekharan, Subahshini; Mayo, Neil; Corley, Martin

    2009-02-01

    Although Internet-based experiments are gaining in popularity, most studies rely on directly evaluating participants' responses rather than response times. In the present article, we present two experiments that demonstrate the feasibility of collecting response latency data over the World-Wide Web using WebExp-a software package designed to run psychological experiments over the Internet. Experiment 1 uses WebExp to collect measurements for known time intervals (generated using keyboard repetition). The resulting measurements are found to be accurate across platforms and load conditions. In Experiment 2, we use WebExp to replicate a lab-based self-paced reading study from the psycholinguistic literature. The data of the Web-based replication correlate significantly with those of the original study and show the same main effects and interactions. We conclude that WebExp can be used to obtain reliable response time data, at least for the self-paced reading paradigm.

  8. On understanding and predicting groundwater response time.

    PubMed

    Sophocleous, Marios

    2012-01-01

    An aquifer system, when perturbed, has a tendency to evolve to a new equilibrium, a process that can take from just a few seconds to possibly millions of years. The time scale on which a system adjusts to a new equilibrium is often referred to as "response time" or "lag time." Because groundwater response time affects the physical and economic viability of various management options in a basin, natural resource managers are increasingly interested in incorporating it into policy. However, the processes of how groundwater responds to land-use change are not well understood, making it difficult to predict the timing of groundwater response to such change. The difficulty in estimating groundwater response time is further compounded because the data needed to quantify this process are not usually readily available. This article synthesizes disparate pieces of information on aquifer response times into a relatively brief but hopefully comprehensive review that the community of water professionals can use to better assess the impact of aquifer response time in future groundwater management investigations. A brief exposition on dimensional/scaling analysis is presented first, followed by an overview of aquifer response time for simplified aquifer systems. The aquifer response time is considered first from a water-quantity viewpoint and later expanded to incorporate groundwater age and water-quality aspects. Monitoring programs today, as well as water policies and regulations, should address this issue of aquifer response time so that more realistic management expectations can be reached.

  9. Complete Dentures: Designing Occlusal Registration Blocks to Save Clinical Time and Improve Accuracy.

    PubMed

    Bishop, Mark; Johnson, Tony

    2015-04-01

    The techniques described in this article are based on facial measurements and an analysis of the patient's existing dentures to provide measurements that will enable registration blocks to be constructed for individual patients rather than the arbitrarily produced block more commonly seen. Employing the methods shown will lead to a saving in clinical time and contribute to a more accurate registration. It is important to remember that the technician can only provide occlusal registration blocks of the appropriate dimensions if the clinician has assessed the patient and existing dentures and then passed this information to the laboratory. Clinical Relevances: Being able to assess the clinical suitability of a patient's existing dentures and then take measurements from those dentures will allow occlusal registration blocks to be constructed that have the correct dimensions and anatomical features for a particular patient. This will save time during the registration stage and help to improve accuracy.

  10. An ergonomic evaluation of infant life jackets: Donning time & donning accuracy.

    PubMed

    MacDonald, C V; Brooks, C J; Kozey, J W; Habib, A

    2011-01-01

    Canada is considering the development of a new standard for infant/child life jackets. Eight currently available (approved and non-approved) infant/child life jackets were procured for evaluation. Fifty-six participants were chosen as a sample of convenience from the general public for testing. The life jackets were divided into two groups of four, which were donned on a soft infant manikin procured from the Red Cross. In 224 attempts at donning, only 43 (19%) attempts resulted in the life jacket being donned correctly in less than 1 min. Only one life jacket came close to a good design and passed the life jacket standard for donning time and accuracy. Failure rates were observed across all the participants irrespective of age, gender, experience with children and experience with recreational marine equipment. Accuracy and speed of donning the life jacket were hampered as the number of donning sub-tasks increased. It was concluded that it is possible to design a life jacket that can be donned correctly in under 1 min. The life jacket must be of simple, intuitive design and fall naturally into the anatomical shape of the child. A minimum number of ties, zips and clips should be used in the design, and if such connectors are used they should be color coded or of different shapes and sizes to avoid confusion.

  11. More than accuracy: Nonverbal dialects modulate the time course of vocal emotion recognition across cultures.

    PubMed

    Jiang, Xiaoming; Paulmann, Silke; Robin, Jessica; Pell, Marc D

    2015-06-01

    Using a gating paradigm, this study investigated the nature of the in-group advantage in vocal emotion recognition by comparing 2 distinct cultures. Pseudoutterances conveying 4 basic emotions, expressed in English and Hindi, were presented to English and Hindi listeners. In addition to hearing full utterances, each stimulus was gated from its onset to construct 5 processing intervals to pinpoint when the in-group advantage emerges, and whether this differs when listening to a foreign language (English participants judging Hindi) or a second language (Hindi participants judging English). An index of the mean emotion identification point for each group and unbiased measures of accuracy at each time point was calculated. Results showed that in each language condition, native listeners were faster and more accurate than non-native listeners to recognize emotions. The in-group advantage emerged in both conditions after processing 400 ms to 500 ms of acoustic information. In the bilingual Hindi group, greater oral proficiency in English predicted faster and more accurate recognition of English emotional expressions. Consistent with dialect theory, our findings provide new evidence that nonverbal dialects impede both the accuracy and the efficiency of vocal emotion processing in cross-cultural settings, even when individuals are highly proficient in the out-group target language.

  12. Accuracy of rate coding: When shorter time window and higher spontaneous activity help

    NASA Astrophysics Data System (ADS)

    Levakova, Marie; Tamborrino, Massimiliano; Kostal, Lubomir; Lansky, Petr

    2017-02-01

    It is widely accepted that neuronal firing rates contain a significant amount of information about the stimulus intensity. Nevertheless, theoretical studies on the coding accuracy inferred from the exact spike counting distributions are rare. We present an analysis based on the number of observed spikes assuming the stochastic perfect integrate-and-fire model with a change point, representing the stimulus onset, for which we calculate the corresponding Fisher information to investigate the accuracy of rate coding. We analyze the effect of changing the duration of the time window and the influence of several parameters of the model, in particular the level of the presynaptic spontaneous activity and the level of random fluctuation of the membrane potential, which can be interpreted as noise of the system. The results show that the Fisher information is nonmonotonic with respect to the length of the observation period. This counterintuitive result is caused by the discrete nature of the count of spikes. We observe also that the signal can be enhanced by noise, since the Fisher information is nonmonotonic with respect to the level of spontaneous activity and, in some cases, also with respect to the level of fluctuation of the membrane potential.

  13. Intracranial aneurysms: Diagnostics accuracy of three-dimensional, fourier transform, time-of-flight MR angiography

    SciTech Connect

    Korogi, Yukunori; Takahashi, Mutsumasa; Mabuchi, Nobuhisa; Miki, Hitoshi; Fujiwara, Satoru; Horikawa, Yoshiharu; Nakagawa, Toshio; O`Uchi, Toshihiro; Watabe, Tsuneya; Shiga, Hayao

    1994-10-01

    To assess the accuracy of three-dimensional, Fourier transform, time-of-flight magnetic resonance (MR) angiography in the identification of intracranial aneurysms. MR angiograms of 126 patients (59 male and 67 female patients, aged 12-77 years) with various intracranial vascular lesions were evaluated. Seventy-eight aneurysms, including 60 less than 5 mm in diameter, in 61 patients were depicted at conventional angiography. Eight projection images, as well as one axial collapsed MR angiogram obtained with a maximum-intensity projection algorithm, were used for evaluation. Sensitivity for the five observers ranged from 58% to 68% (mean, 63%). Higher sensitivity was achieved for anterior communicating and middle cerebral artery aneurysms, while that for internal carotid artery aneurysms was poor. Sensitivities for small and medium aneurysms ranged from 50% to 60% (mean, 56%) and from 77% to 94% (mean, 85%), respectively. MR angiography can depict intracranial aneurysms 5 mm or larger with good accuracy but is less useful for the identification of smaller aneurysms. 12 refs., 5 figs., 5 tabs.

  14. Prismatic displacement effect of progressive multifocal glasses on reaction time and accuracy in elderly people

    PubMed Central

    Ellison, Ashton C; Campbell, A John; Robertson, M Clare; Sanderson, Gordon F

    2014-01-01

    Background Multifocal glasses (bifocals, trifocals, and progressives) increase the risk of falling in elderly people, but how they do so is unclear. To explain why glasses with progressive addition lenses increase the risk of falls and whether this can be attributed to false projection, this study aimed to 1) map the prismatic displacement of a progressive lens, and 2) test whether this displacement impaired reaction time and accuracy. Methods The reaction times of healthy ≥75-year-olds (31 participants) were measured when grasping for a bar and touching a black line. Participants performed each test twice, wearing their progressives and new, matched single vision (distance) glasses in random order. The line and bar targets were positioned according to the maximum and minimum prismatic displacement effect through the progressive lens, mapped using a focimeter. Results Progressive spectacle lenses have large areas of prismatic displacement in the central visual axis and edges. Reaction time was faster for progressives compared with single vision glasses with a centrally-placed horizontal grab bar (mean difference 101 ms, P=0.011 [repeated measures analysis]) and a horizontal black line placed 300 mm below center (mean difference 80 ms, P=0.007). There was no difference in accuracy between the two types of glasses. Conclusion Older people appear to adapt to the false projection of progressives in the central visual axis. This adaptation means that swapping to new glasses or a large change in prescription may lead to a fall. Frequently updating glasses may be more beneficial. PMID:24872674

  15. Neural network incorporating meal information improves accuracy of short-time prediction of glucose concentration.

    PubMed

    Zecchin, Chiara; Facchinetti, Andrea; Sparacino, Giovanni; De Nicolao, Giuseppe; Cobelli, Claudio

    2012-06-01

    Diabetes mellitus is one of the most common chronic diseases, and a clinically important task in its management is the prevention of hypo/hyperglycemic events. This can be achieved by exploiting continuous glucose monitoring (CGM) devices and suitable short-term prediction algorithms able to infer future glycemia in real time. In the literature, several methods for short-time glucose prediction have been proposed, most of which do not exploit information on meals, and use past CGM readings only. In this paper, we propose an algorithm for short-time glucose prediction using past CGM sensor readings and information on carbohydrate intake. The predictor combines a neural network (NN) model and a first-order polynomial extrapolation algorithm, used in parallel to describe, respectively, the nonlinear and the linear components of glucose dynamics. Information on the glucose rate of appearance after a meal is described by a previously published physiological model. The method is assessed on 20 simulated datasets and on 9 real Abbott FreeStyle Navigator datasets, and its performance is successfully compared with that of a recently proposed NN glucose predictor. Results suggest that exploiting meal information improves the accuracy of short-time glucose prediction.

  16. Objective Error Criterion for Evaluation of Mapping Accuracy Based on Sensor Time-of-Flight Measurements.

    PubMed

    Barshan, Billur

    2008-12-15

    An objective error criterion is proposed for evaluating the accuracy of maps of unknown environments acquired by making range measurements with different sensing modalities and processing them with different techniques. The criterion can also be used for the assessment of goodness of fit of curves or shapes fitted to map points. A demonstrative example from ultrasonic mapping is given based on experimentally acquired time-of-flight measurements and compared with a very accurate laser map, considered as absolute reference. The results of the proposed criterion are compared with the Hausdorff metric and the median error criterion results. The error criterion is sufficiently general and flexible that it can be applied to discrete point maps acquired with other mapping techniques and sensing modalities as well.

  17. Improving Accuracy in Arrhenius Models of Cell Death: Adding a Temperature-Dependent Time Delay.

    PubMed

    Pearce, John A

    2015-12-01

    The Arrhenius formulation for single-step irreversible unimolecular reactions has been used for many decades to describe the thermal damage and cell death processes. Arrhenius predictions are acceptably accurate for structural proteins, for some cell death assays, and for cell death at higher temperatures in most cell lines, above about 55 °C. However, in many cases--and particularly at hyperthermic temperatures, between about 43 and 55 °C--the particular intrinsic cell death or damage process under study exhibits a significant "shoulder" region that constant-rate Arrhenius models are unable to represent with acceptable accuracy. The primary limitation is that Arrhenius calculations always overestimate the cell death fraction, which leads to severely overoptimistic predictions of heating effectiveness in tumor treatment. Several more sophisticated mathematical model approaches have been suggested and show much-improved performance. But simpler models that have adequate accuracy would provide useful and practical alternatives to intricate biochemical analyses. Typical transient intrinsic cell death processes at hyperthermic temperatures consist of a slowly developing shoulder region followed by an essentially constant-rate region. The shoulder regions have been demonstrated to arise chiefly from complex functional protein signaling cascades that generate delays in the onset of the constant-rate region, but may involve heat shock protein activity as well. This paper shows that acceptably accurate and much-improved predictions in the simpler Arrhenius models can be obtained by adding a temperature-dependent time delay. Kinetic coefficients and the appropriate time delay are obtained from the constant-rate regions of the measured survival curves. The resulting predictions are seen to provide acceptably accurate results while not overestimating cell death. The method can be relatively easily incorporated into numerical models. Additionally, evidence is presented

  18. Accuracy of time-domain and frequency-domain methods used to characterize catchment transit time distributions

    NASA Astrophysics Data System (ADS)

    Godsey, S. E.; Kirchner, J. W.

    2008-12-01

    The mean residence time - the average time that it takes rainfall to reach the stream - is a basic parameter used to characterize catchment processes. Heterogeneities in these processes lead to a distribution of travel times around the mean residence time. By examining this travel time distribution, we can better predict catchment response to contamination events. A catchment system with shorter residence times or narrower distributions will respond quickly to contamination events, whereas systems with longer residence times or longer-tailed distributions will respond more slowly to those same contamination events. The travel time distribution of a catchment is typically inferred from time series of passive tracers (e.g., water isotopes or chloride) in precipitation and streamflow. Variations in the tracer concentration in streamflow are usually damped compared to those in precipitation, because precipitation inputs from different storms (with different tracer signatures) are mixed within the catchment. Mathematically, this mixing process is represented by the convolution of the travel time distribution and the precipitation tracer inputs to generate the stream tracer outputs. Because convolution in the time domain is equivalent to multiplication in the frequency domain, it is relatively straightforward to estimate the parameters of the travel time distribution in either domain. In the time domain, the parameters describing the travel time distribution are typically estimated by maximizing the goodness of fit between the modeled and measured tracer outputs. In the frequency domain, the travel time distribution parameters can be estimated by fitting a power-law curve to the ratio of precipitation spectral power to stream spectral power. Differences between the methods of parameter estimation in the time and frequency domain mean that these two methods may respond differently to variations in data quality, record length and sampling frequency. Here we evaluate how

  19. Estimating subsurface water volumes and transit times in Hokkaido river catchments, Japan, using high-accuracy tritium analysis

    NASA Astrophysics Data System (ADS)

    Gusyev, Maksym; Yamazaki, Yusuke; Morgenstern, Uwe; Stewart, Mike; Kashiwaya, Kazuhisa; Hirai, Yasuyuki; Kuribayashi, Daisuke; Sawano, Hisaya

    2015-04-01

    The goal of this study is to estimate subsurface water transit times and volumes in headwater catchments of Hokkaido, Japan, using the New Zealand high-accuracy tritium analysis technique. Transit time provides insights into the subsurface water storage and therefore provides a robust and quick approach to quantifying the subsurface groundwater volume. Our method is based on tritium measurements in river water. Tritium is a component of meteoric water, decays with a half-life of 12.32 years, and is inert in the subsurface after the water enters the groundwater system. Therefore, tritium is ideally suited for characterization of the catchment's responses and can provide information on mean water transit times up to 200 years. Only in recent years has it become possible to use tritium for dating of stream and river water, due to the fading impact of the bomb-tritium from thermo-nuclear weapons testing, and due to improved measurement accuracy for the extremely low natural tritium concentrations. Transit time of the water discharge is one of the most crucial parameters for understanding the response of catchments and estimating subsurface water volume. While many tritium transit time studies have been conducted in New Zealand, only a limited number of tritium studies have been conducted in Japan. In addition, the meteorological, orographic and geological conditions of Hokkaido Island are similar to those in parts of New Zealand, allowing for comparison between these regions. In 2014, three field trips were conducted in Hokkaido in June, July and October to sample river water at river gauging stations operated by the Ministry of Land, Infrastructure, Transport and Tourism (MLIT). These stations have altitudes between 36 m and 860 m MSL and drainage areas between 45 and 377 km2. Each sampled point is located upstream of MLIT dams, with hourly measurements of precipitation and river water levels enabling us to distinguish between the snow melt and baseflow contributions

  20. Using precise word timing information improves decoding accuracy in a multiband-accelerated multimodal reading experiment

    PubMed Central

    Vu, An T.; Phillips, Jeffrey S.; Kay, Kendrick; Phillips, Matthew E.; Johnson, Matthew R.; Shinkareva, Svetlana V.; Tubridy, Shannon; Millin, Rachel; Grossman, Murray; Gureckis, Todd; Bhattacharyya, Rajan; Yacoub, Essa

    2017-01-01

    The blood-oxygen-level-dependent (BOLD) signal measured in functional magnetic resonance imaging (fMRI) experiments is generally regarded as sluggish and poorly suited for probing neural function at the rapid timescales involved in sentence comprehension. However, recent studies have shown the value of acquiring data with very short repetition times (TRs), not merely in terms of improvements in contrast to noise ratio (CNR) through averaging, but also in terms of additional fine-grained temporal information. Using multiband-accelerated fMRI, we achieved whole-brain scans at 3-mm resolution with a TR of just 500 ms at both 3T and 7T field strengths. By taking advantage of word timing information, we found that word decoding accuracy across two separate sets of scan sessions improved significantly, with better overall performance at 7T than at 3T. The effect of TR was also investigated; we found that substantial word timing information can be extracted using fast TRs, with diminishing benefits beyond TRs of 1000 ms. PMID:27686111

  1. Using precise word timing information improves decoding accuracy in a multiband-accelerated multimodal reading experiment.

    PubMed

    Vu, An T; Phillips, Jeffrey S; Kay, Kendrick; Phillips, Matthew E; Johnson, Matthew R; Shinkareva, Svetlana V; Tubridy, Shannon; Millin, Rachel; Grossman, Murray; Gureckis, Todd; Bhattacharyya, Rajan; Yacoub, Essa

    2016-01-01

    The blood-oxygen-level-dependent (BOLD) signal measured in functional magnetic resonance imaging (fMRI) experiments is generally regarded as sluggish and poorly suited for probing neural function at the rapid timescales involved in sentence comprehension. However, recent studies have shown the value of acquiring data with very short repetition times (TRs), not merely in terms of improvements in contrast to noise ratio (CNR) through averaging, but also in terms of additional fine-grained temporal information. Using multiband-accelerated fMRI, we achieved whole-brain scans at 3-mm resolution with a TR of just 500 ms at both 3T and 7T field strengths. By taking advantage of word timing information, we found that word decoding accuracy across two separate sets of scan sessions improved significantly, with better overall performance at 7T than at 3T. The effect of TR was also investigated; we found that substantial word timing information can be extracted using fast TRs, with diminishing benefits beyond TRs of 1000 ms.

  2. High-accuracy time- and space-resolved Stark shift measurements

    SciTech Connect

    Bailey, J.E.; Adams, R.; Carlson, A.L.; Ching, C.H.; Filuk, A.B.; Lake, P.

    1996-07-01

    Stark-shift measurements using emission spectroscopy are a powerful tool for advancing understanding in many plasma physics experiments. The authors use simultaneous 2-D-spatial and time-resolved spectra to study the electric field evolution in the 20 TW Particle Beam Fusion Accelerator II ion diode acceleration gap. Fiber optic arrays transport light from the gap to remote streaked spectrographs operated in a multiplexed mode that enables recording time-resolved spectra from eight spatial locations on a single instrument. Design optimization and characterization measurements of the multiplexed spectrograph properties include the astigmatism, resolution, dispersion variation, and sensitivity. A semi-automated line-fitting procedure determines the Stark shift and the related uncertainties. Fields up to 10 MV/cm are measured with an accuracy {+-}2--4%. Detailed tests of the fitting procedure confirm that the wavelength shift uncertainties are accurate to better than {+-}20%. Development of an active spectroscopy probe technique that uses laser-induced fluorescence from an injected atomic beam to obtain 3-D space- and time-resolved measurements of the electric and magnetic fields is in progress.

  3. Silicon Timing Response to Particles and Light

    SciTech Connect

    Ronzhin, Anatoly; Spiropulu, Maria

    2015-01-01

    It is observed growing interest to fast timing detectors in high energy physics, related, for example, with collider luminosity increase (LHC) [1]. The options of CMS [2] calorimeter upgrade based on silicon detectors renewed interest to the timing study of this type of detectors. The article is devoted to study of silicon timing response to particles and light.

  4. Keystroke dynamics and timing: accuracy, precision and difference between hands in pianist's performance.

    PubMed

    Minetti, Alberto E; Ardigò, Luca P; McKee, Tom

    2007-01-01

    A commercially available acoustic grand piano, originally provided with keystroke speed sensors, is proposed as a standard instrument to quantitatively assess the technical side of pianist's performance, after the mechanical characteristics of the keyboard have been measured. We found a positional dependence of the relationship between the applied force and the resulting downstroke speed (i.e. treble keys descend fastest) due to the different hammer/hammer shaft mass to be accelerated. When this effect was removed by a custom software, the ability of 14 pianists was analysed in terms of variability in stroke intervals and keystroke speeds. C-major scales played by separate hands at different imposed tempos and at 5 subjectively chosen graded force levels were analysed to get insights into the achieved neuromuscular control. Accuracy and precision of time intervals and descent velocity of keystrokes were obtained by processing the generated MIDI files. The results quantitatively show: the difference between hands, the trade off between force range and tempo, and between time interval precision and tempo, the lower precision of descent speed associated to 'soft' playing, etc. Those results reflect well-established physiological and motor control characteristics of our movement system. Apart from revealing fundamental aspects of pianism, the proposed method could be used as a standard tool also for ergonomic (e.g. the mechanical work and power of playing), didactic and rehabilitation monitoring of pianists.

  5. Vehicle Position Estimation Based on Magnetic Markers: Enhanced Accuracy by Compensation of Time Delays.

    PubMed

    Byun, Yeun-Sub; Jeong, Rag-Gyo; Kang, Seok-Won

    2015-11-13

    The real-time recognition of absolute (or relative) position and orientation on a network of roads is a core technology for fully automated or driving-assisted vehicles. This paper presents an empirical investigation of the design, implementation, and evaluation of a self-positioning system based on a magnetic marker reference sensing method for an autonomous vehicle. Specifically, the estimation accuracy of the magnetic sensing ruler (MSR) in the up-to-date estimation of the actual position was successfully enhanced by compensating for time delays in signal processing when detecting the vertical magnetic field (VMF) in an array of signals. In this study, the signal processing scheme was developed to minimize the effects of the distortion of measured signals when estimating the relative positional information based on magnetic signals obtained using the MSR. In other words, the center point in a 2D magnetic field contour plot corresponding to the actual position of magnetic markers was estimated by tracking the errors between pre-defined reference models and measured magnetic signals. The algorithm proposed in this study was validated by experimental measurements using a test vehicle on a pilot network of roads. From the results, the positioning error was found to be less than 0.04 m on average in an operational test.

  6. Do missing data influence the accuracy of divergence-time estimation with BEAST?

    PubMed

    Zheng, Yuchi; Wiens, John J

    2015-04-01

    Time-calibrated phylogenies have become essential to evolutionary biology. A recurrent and unresolved question for dating analyses is whether genes with missing data cells should be included or excluded. This issue is particularly unclear for the most widely used dating method, the uncorrelated lognormal approach implemented in BEAST. Here, we test the robustness of this method to missing data. We compare divergence-time estimates from a nearly complete dataset (20 nuclear genes for 32 species of squamate reptiles) to those from subsampled matrices, including those with 5 or 2 complete loci only and those with 5 or 8 incomplete loci added. In general, missing data had little impact on estimated dates (mean error of ∼5Myr per node or less, given an overall age of ∼220Myr in squamates), even when 80% of sampled genes had 75% missing data. Mean errors were somewhat higher when all genes were 75% incomplete (∼17Myr). However, errors increased dramatically when only 2 of 9 fossil calibration points were included (∼40Myr), regardless of missing data. Overall, missing data (and even numbers of genes sampled) may have only minor impacts on the accuracy of divergence dating with BEAST, relative to the dramatic effects of fossil calibrations.

  7. Vehicle Position Estimation Based on Magnetic Markers: Enhanced Accuracy by Compensation of Time Delays

    PubMed Central

    Byun, Yeun-Sub; Jeong, Rag-Gyo; Kang, Seok-Won

    2015-01-01

    The real-time recognition of absolute (or relative) position and orientation on a network of roads is a core technology for fully automated or driving-assisted vehicles. This paper presents an empirical investigation of the design, implementation, and evaluation of a self-positioning system based on a magnetic marker reference sensing method for an autonomous vehicle. Specifically, the estimation accuracy of the magnetic sensing ruler (MSR) in the up-to-date estimation of the actual position was successfully enhanced by compensating for time delays in signal processing when detecting the vertical magnetic field (VMF) in an array of signals. In this study, the signal processing scheme was developed to minimize the effects of the distortion of measured signals when estimating the relative positional information based on magnetic signals obtained using the MSR. In other words, the center point in a 2D magnetic field contour plot corresponding to the actual position of magnetic markers was estimated by tracking the errors between pre-defined reference models and measured magnetic signals. The algorithm proposed in this study was validated by experimental measurements using a test vehicle on a pilot network of roads. From the results, the positioning error was found to be less than 0.04 m on average in an operational test. PMID:26580622

  8. Diagnostic accuracy and turnaround time of the Xpert MTB/RIF assay in routine clinical practice.

    PubMed

    Kwak, Nakwon; Choi, Sun Mi; Lee, Jinwoo; Park, Young Sik; Lee, Chang-Hoon; Lee, Sang-Min; Yoo, Chul-Gyu; Kim, Young Whan; Han, Sung Koo; Yim, Jae-Joon

    2013-01-01

    The Xpert MTB/RIF assay was introduced for timely and accurate detection of tuberculosis (TB). The aim of this study was to determine the diagnostic accuracy and turnaround time (TAT) of Xpert MTB/RIF assay in clinical practice in South Korea. We retrospectively reviewed the medical records of patients in whom Xpert MTB/RIF assay using sputum were requested. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for the diagnosis of pulmonary tuberculosis (PTB) and detection of rifampicin resistance were calculated. In addition, TAT of Xpert MTB/RIF assay was compared with those of other tests. Total 681 patients in whom Xpert MTB/RIF assay was requested were included in the analysis. The sensitivity, specificity, PPV and NPV of Xpert MTB/RIF assay for diagnosis of PTB were 79.5% (124/156), 100.0% (505/505), 100.0% (124/124) and 94.0% (505/537), respectively. Those for the detection of rifampicin resistance were 57.1% (8/14), 100.0% (113/113), 100.0% (8/8) and 94.9% (113/119), respectively. The median TAT of Xpert MTB/RIF assay to the report of results and results confirmed by physicians in outpatient settings were 0 (0-1) and 6 (3-7) days, respectively. Median time to treatment after initial evaluation was 7 (4-9) days in patients with Xpert MTB/RIF assay, but was 21 (7-33.5) days in patients without Xpert MTB/RIF assay. Xpert MTB/RIF assay showed acceptable sensitivity and excellent specificity for the diagnosis of PTB and detection of rifampicin resistance in areas with intermediate TB burden. Additionally, the assay decreased time to the initiation of anti-TB drugs through shorter TAT.

  9. Cognitive Reflection, Decision Biases, and Response Times

    PubMed Central

    Alós-Ferrer, Carlos; Garagnani, Michele; Hügelschäfer, Sabine

    2016-01-01

    We present novel evidence on response times and personality traits in standard questions from the decision-making literature where responses are relatively slow (medians around half a minute or above). To this end, we measured response times in a number of incentivized, framed items (decisions from description) including the Cognitive Reflection Test, two additional questions following the same logic, and a number of classic questions used to study decision biases in probability judgments (base-rate neglect, the conjunction fallacy, and the ratio bias). All questions create a conflict between an intuitive process and more deliberative thinking. For each item, we then created a non-conflict version by either making the intuitive impulse correct (resulting in an alignment question), shutting it down (creating a neutral question), or making it dominant (creating a heuristic question). For CRT questions, the differences in response times are as predicted by dual-process theories, with alignment and heuristic variants leading to faster responses and neutral questions to slower responses than the original, conflict questions. For decision biases (where responses are slower), evidence is mixed. To explore the possible influence of personality factors on both choices and response times, we used standard personality scales including the Rational-Experiential Inventory and the Big Five, and used them as controls in regression analysis. PMID:27713710

  10. The Value of Response Times in Item Response Modeling

    ERIC Educational Resources Information Center

    Molenaar, Dylan

    2015-01-01

    A new and very interesting approach to the analysis of responses and response times is proposed by Goldhammer (this issue). In his approach, differences in the speed-ability compromise within respondents are considered to confound the differences in ability between respondents. These confounding effects of speed on the inferences about ability can…

  11. Response time for multilayered platinum resistance thermometers

    NASA Technical Reports Server (NTRS)

    Pandey, D. K.; Ash, R. L.

    1985-01-01

    Response time constants for several multilayered temperature transducers were determined numerically by using Martin Marietta's MITAS software package which is available at NASA Langley Research Center. Present results were found in close agreement with the solutions reported in the literature, thus, the capability of MITAS was justified. On the basis of experiences gained, the MITAS is recommended for use in predicting the response time constants of sensors by an in-situ technique.

  12. Validating the Accuracy of Reaction Time Assessment on Computer-Based Tablet Devices.

    PubMed

    Schatz, Philip; Ybarra, Vincent; Leitner, Donald

    2015-08-01

    Computer-based assessment has evolved to tablet-based devices. Despite the availability of tablets and "apps," there is limited research validating their use. We documented timing delays between stimulus presentation and (simulated) touch response on iOS devices (3rd- and 4th-generation Apple iPads) and Android devices (Kindle Fire, Google Nexus, Samsung Galaxy) at response intervals of 100, 250, 500, and 1,000 milliseconds (ms). Results showed significantly greater timing error on Google Nexus and Samsung tablets (81-97 ms), than Kindle Fire and Apple iPads (27-33 ms). Within Apple devices, iOS 7 obtained significantly lower timing error than iOS 6. Simple reaction time (RT) trials (250 ms) on tablet devices represent 12% to 40% error (30-100 ms), depending on the device, which decreases considerably for choice RT trials (3-5% error at 1,000 ms). Results raise implications for using the same device for serial clinical assessment of RT using tablets, as well as the need for calibration of software and hardware.

  13. Response Latency as a Predictor of the Accuracy of Children's Reports

    ERIC Educational Resources Information Center

    Ackerman, Rakefet; Koriat, Asher

    2011-01-01

    Researchers have explored various diagnostic cues to the accuracy of information provided by child eyewitnesses. Previous studies indicated that children's confidence in their reports predicts the relative accuracy of these reports, and that the confidence-accuracy relationship generally improves as children grow older. In this study, we examined…

  14. A high accuracy broadband measurement system for time resolved complex bioimpedance measurements.

    PubMed

    Kaufmann, S; Malhotra, A; Ardelt, G; Ryschka, M

    2014-06-01

    Bioimpedance measurements are useful tools in biomedical engineering and life science. Bioimpedance is the electrical impedance of living tissue and can be used in the analysis of various physiological parameters. Bioimpedance is commonly measured by injecting a small well known alternating current via surface electrodes into an object under test and measuring the resultant surface voltages. It is non-invasive, painless and has no known hazards. This work presents a field programmable gate array based high accuracy broadband bioimpedance measurement system for time resolved bioimpedance measurements. The system is able to measure magnitude and phase of complex impedances under test in a frequency range of about 10-500 kHz with excitation currents from 10 µA to 5 mA. The overall measurement uncertainties stay below 1% for the impedance magnitude and below 0.5° for the phase in most measurement ranges. Furthermore, the described system has a sample rate of up to 3840 impedance spectra per second. The performance of the bioimpedance measurement system is demonstrated with a resistor based system calibration and with measurements on biological samples.

  15. A benchmark test of accuracy and precision in estimating dynamical systems characteristics from a time series.

    PubMed

    Rispens, S M; Pijnappels, M; van Dieën, J H; van Schooten, K S; Beek, P J; Daffertshofer, A

    2014-01-22

    Characteristics of dynamical systems are often estimated to describe physiological processes. For instance, Lyapunov exponents have been determined to assess the stability of the cardio-vascular system, respiration, and, more recently, human gait and posture. However, the systematic evaluation of the accuracy and precision of these estimates is problematic because the proper values of the characteristics are typically unknown. We fill this void with a set of standardized time series with well-defined dynamical characteristics that serve as a benchmark. Estimates ought to match these characteristics, at least to good approximation. We outline a procedure to employ this generic benchmark test and illustrate its capacity by examining methods for estimating the maximum Lyapunov exponent. In particular, we discuss algorithms by Wolf and co-workers and by Rosenstein and co-workers and evaluate their performances as a function of signal length and signal-to-noise ratio. In all scenarios, the precision of Rosenstein's algorithm was found to be equal to or greater than Wolf's algorithm. The latter, however, appeared more accurate if reasonably large signal lengths are available and noise levels are sufficiently low. Due to its modularity, the presented benchmark test can be used to evaluate and tune any estimation method to perform optimally for arbitrary experimental data.

  16. Stability and accuracy of free surface time integration in viscous flows

    NASA Astrophysics Data System (ADS)

    Rose, Ian; Buffett, Bruce; Heister, Timo

    2017-01-01

    Geodynamic simulations increasingly rely on models with a true free surface to investigate questions of dynamic topography, tectonic deformation, gravity perturbations, and global mantle convection. However, implementations of free surface boundary conditions have proven challenging from a standpoint of accuracy, robustness, and stability. In particular, time integration of a free surface tends to suffer from a numerical instability that manifests as sloshing surface motions, also known as the "drunken sailor" instability. This instability severely limits stable timestep sizes to those much smaller than can be used in geodynamic simulations without a free surface. Several schemes have been proposed in the literature to deal with these instabilities. Here we analyze the problem of creeping viscous flow with a free surface and discuss the origin of these instabilities. We demonstrate their cause and how existing stabilization schemes work to damp them out. We also propose a new scheme for removing instabilities from free surface calculations. It does not require modifications to the system matrix, nor additional variables, but is instead an explicit scheme based on nonstandard finite differences. It relies on a single stabilization parameter which may be identified with the smallest relaxation timescale of the free surface. Finally, we present numerical results to show the effectiveness of the new approach and discuss the free surface implementation in the open source, community based mantle convection software ASPECT.

  17. Accuracy of Perceived Estimated Travel Time by EMS to a Trauma Center in San Bernardino County, California

    PubMed Central

    Neeki, Michael M.; MacNeil, Colin; Toy, Jake; Dong, Fanglong; Vara, Richard; Powell, Joe; Pennington, Troy; Kwong, Eugene

    2016-01-01

    Introduction Mobilization of trauma resources has the potential to cause ripple effects throughout hospital operations. One major factor affecting efficient utilization of trauma resources is a discrepancy between the prehospital estimated time of arrival (ETA) as communicated by emergency medical services (EMS) personnel and their actual time of arrival (TOA). The current study aimed to assess the accuracy of the perceived prehospital estimated arrival time by EMS personnel in comparison to their actual arrival time at a Level II trauma center in San Bernardino County, California. Methods This retrospective study included traumas classified as alerts or activations that were transported to Arrowhead Regional Medical Center in 2013. We obtained estimated arrival time and actual arrival time for each transport from the Surgery Department Trauma Registry. The difference between the median of ETA and actual TOA by EMS crews to the trauma center was calculated for these transports. Additional variables assessed included time of day and month during which the transport took place. Results A total of 2,454 patients classified as traumas were identified in the Surgery Department Trauma Registry. After exclusion of trauma consults, walk-ins, handoffs between agencies, downgraded traumas, traumas missing information, and traumas transported by agencies other than American Medical Response, Ontario Fire, Rialto Fire or San Bernardino County Fire, we included a final sample size of 555 alert and activation classified traumas in the final analysis. When combining all transports by the included EMS agencies, the median of the ETA was 10 minutes and the median of the actual TOA was 22 minutes (median of difference=9 minutes, p<0.0001). Furthermore, when comparing the difference between trauma alerts and activations, trauma activations demonstrated an equal or larger difference in the median of the estimated and actual time of arrival (p<0.0001). We also found month and time of

  18. Hierarchical Bayes Models for Response Time Data

    ERIC Educational Resources Information Center

    Craigmile, Peter F.; Peruggia, Mario; Van Zandt, Trisha

    2010-01-01

    Human response time (RT) data are widely used in experimental psychology to evaluate theories of mental processing. Typically, the data constitute the times taken by a subject to react to a succession of stimuli under varying experimental conditions. Because of the sequential nature of the experiments there are trends (due to learning, fatigue,…

  19. The functional independence of response latency and accuracy: implications for the concept of conceptual tempo.

    PubMed

    Williams, M; Lahey, B B

    1977-12-01

    Kagan (1965a) developed the concepts of impulsive and reflective cognitive styles (conceptual tempo) to add a new dimension to the understanding and assessment of human intelligence. Although latency (the principal component of conceptual tempo) is negatively correlated with academic performance, it may not be necessary to modify latency in order to modify accuracy.. With 40 disadvantaged preschool children, it was found that reinforcing long latencies in choice tasks did not increase accuracy and vice versa, and that reinforcing both long latencies and accuracy was no more effective than reinforcing accuracy alone. These data were used to question the usefulness of the construct of conceptual tempo.

  20. Effect of expertise on coincident-timing accuracy in a fast ball game.

    PubMed

    Ripoll, H; Latiri, I

    1997-12-01

    The aim of this study was to examine the effect of intensive practice in table tennis on perceptual coincident timing. The main question was whether the perceptual demands encountered in fast ball sports produce modifications of the perceptual visual system. Expert table tennis players and novices were compared in a perceptual task which consisted of estimating, by pressing a key, the arrival of a moving stimulus at a target. The stimulus, which was presented either at constant velocity or at constant deceleration, reproduced as closely as possible the natural visual demands encountered in table tennis. The difference between the time of response and the time of arrival of the stimulus at a target position was measured over 40 trials for each of the 16 participants. The results showed no effect of expertise under the constant-velocity condition but an effect under the decelerative condition, indicating that experts were less trajectory-dependent than novices. This result was interpreted as reflecting a better adaptation of the perceptual system of experts to the constraints encountered during table tennis and specifically to the perceptual demands resulting from varied and decelerated ball trajectories. Finally, some limitations of the coincidence anticipation procedure are highlighted, concerning its use in practical settings for evaluating athletes or detecting sport talents, and the need for the simulation conditions during testing to reproduce as closely as possible the perceptual demands of real life is discussed.

  1. A Ballistic Model of Choice Response Time

    ERIC Educational Resources Information Center

    Brown, Scott; Heathcote, Andrew

    2005-01-01

    Almost all models of response time (RT) use a stochastic accumulation process. To account for the benchmark RT phenomena, researchers have found it necessary to include between-trial variability in the starting point and/or the rate of accumulation, both in linear (R. Ratcliff & J. N. Rouder, 1998) and nonlinear (M. Usher & J. L. McClelland, 2001)…

  2. RESPONSE TIMES IN DECISION-MAKING TASKS.

    ERIC Educational Resources Information Center

    DAGLE, EVERETT F.; AND OTHERS

    THE HUMAN OPERATOR AFFECTS TOTAL PERFORMANCE OF SEMI-AUTOMATED SYSTEMS, BUT LITTLE IS KNOWN ABOUT HIS SOURCES OF ERROR, PARTICULARLY WITH RESPECT TO RESPONSE TIME. UNDER CONTROLLED LABORATORY CONDITIONS, 37 FRESHMEN AND SOPHOMORE GIRLS ATTENDING JUNIOR COLLEGE WERE ASKED TO GUESS A SERIES OF RANDOM NUMBERS GENERATED BY AN ELECTROMECHANICAL SYSTEM…

  3. Investigation of response time testing requirements

    SciTech Connect

    Swisher, V.I. ); Mayo, C.W. ); Weiss, J. )

    1991-05-01

    The purpose of the Response Time Testing (RTT) Program was to determine if requirements for RTT could be eliminated for specific pressure and differential pressure transmitters and switches. This program was initiated when experience and historical data from a significant number of nuclear power plants indicated that, while RTT is both resource and exposure intensive, an insignificant number of pressure sensor failures have been detected through this type of testing. Assessment of plant response time data and performance of Failure Modes and Effects Analysis (FMEA) on sensor hardware were the mechanisms used by the program to determine the redundancy of RTT in conjunction with other required periodic testing (e.g., calibrations, channel checks, surveillance tests). In general, the FMEA results indicated RTT is redundant to other periodic tests. Results of the program identified only two response time failure modes and two manufacturing/handling defects that may not concurrently affect sensor output. The two failure modes affect a limited number of sensor models. Appropriate testing has been identified in cases where response time degradation may not be coincident with significant sensor output change. 14 refs., 19 figs., 39 tabs.

  4. Real time, high accuracy, relative state estimation for multiple vehicle systems

    NASA Astrophysics Data System (ADS)

    Williamson, Walton Ross

    2000-10-01

    This dissertation presents the development, implementation, and test results from a new instrumentation package for relative navigation between moving vehicles. The instrumentation package on each vehicle is composed of a GPS (Global Positioning System) receiver, an IMU (Inertial Measurement Unit), a wireless communication system, and a modular computer system. The GPS places all vehicles into the same inertial reference frame and provides a common clock allowing synchronization among all instrument packages. The IMU tracks the high frequency motion of the vehicle alleviating the need for a fixed base station. The wireless communication system communicates GPS code and carrier phase measurements and computed state estimates from each vehicle at a rate fast enough to capture the dynamic changes in the vehicles. This data representing both GPS and IMU measurements from each vehicle is fused together on each vehicle to produce position, velocity and attitude estimates relative to the other vehicles. This capability to estimate relative motion without a base station appears unique. Furthermore, the application of fusion algorithms to address this new estimation problem is unique. The use of carrier phase provides very accurate relative measurements. In constructing carrier phase measurement, the integer number of wave lengths between vehicles must be resolved. Although there exist integer resolution schemes, these algorithms are ad hoe. The scheme presented here is based on generating the conditional probability of the hypothesis of each integer given the measurement sequence. This nonlinear filter is an elegant and novel contribution. The entire system is tested in real time in an experiment intended to validate the measurement accuracy. The system built using the algorithms designed in this dissertation is capable of estimating relative range to less than 5 cm. RMS, relative roll and pitch to less than 0.2 degrees RMS, and relative yaw to less than 0.7 degrees RMS

  5. Mass Communication and Political Accuracy: A Comparison of First-Time and Older Voters.

    ERIC Educational Resources Information Center

    Quarles, Rebecca Colwell

    For this study of the relationships between accuracy of political information and attention to various mass-media sources of public-affairs information, personal interviews were conducted with 388 eligible voters in Madison, Wisconsin, and 129 eligible voters in Lexington, Kentucky, during October 1972. Variables measured included education,…

  6. Patterns of Response Times and Response Choices to Science Questions: The Influence of Relative Processing Time

    ERIC Educational Resources Information Center

    Heckler, Andrew F.; Scaife, Thomas M.

    2015-01-01

    We report on five experiments investigating response choices and response times to simple science questions that evoke student "misconceptions," and we construct a simple model to explain the patterns of response choices. Physics students were asked to compare a physical quantity represented by the slope, such as speed, on simple physics…

  7. Structural health monitoring ultrasonic thickness measurement accuracy and reliability of various time-of-flight calculation methods

    NASA Astrophysics Data System (ADS)

    Eason, Thomas J.; Bond, Leonard J.; Lozev, Mark G.

    2016-02-01

    The accuracy, precision, and reliability of ultrasonic thickness structural health monitoring systems are discussed in-cluding the influence of systematic and environmental factors. To quantify some of these factors, a compression wave ultrasonic thickness structural health monitoring experiment is conducted on a flat calibration block at ambient temperature with forty four thin-film sol-gel transducers and various time-of-flight thickness calculation methods. As an initial calibration, the voltage response signals from each sensor are used to determine the common material velocity as well as the signal offset unique to each calculation method. Next, the measurement precision of the thickness error of each method is determined with a proposed weighted censored relative maximum likelihood analysis technique incorporating the propagation of asymmetric measurement uncertainty. The results are presented as upper and lower confidence limits analogous to the a90/95 terminology used in industry recognized Probability-of-Detection assessments. Future work is proposed to apply the statistical analysis technique to quantify measurement precision of various thickness calculation methods under different environmental conditions such as high temperature, rough back-wall surface, and system degradation with an intended application to monitor naphthenic acid corrosion in oil refineries.

  8. The influence of attention on learning and performance: pre-movement time and accuracy in an isometric force production task.

    PubMed

    Lohse, Keith R

    2012-02-01

    Lohse, Sherwood, and Healy (2010) found that an external focus of attention (FOA) improved performance in a dart-throwing task and reduced the time taken between throws, but using the time between trials as a measure of preparation time is relatively crude. Thus, the current experiment analyzed how FOA affects accuracy and pre-movement time in an isometric force production task, to study how FOA affected motor planning. In the current experiment, training with an external focus improved the accuracy of the isometric force production task during training and during retention and transfer testing. During training, an external FOA also significantly reduced pre-movement time in early trials. These findings are interpreted as reduced explicit control of movement as a function of an external FOA, and help to integrate FOA research with other motor control phenomena and neuropsychological theories of motor control.

  9. A quantitative method for evaluating numerical simulation accuracy of time-transient Lamb wave propagation with its applications to selecting appropriate element size and time step.

    PubMed

    Wan, Xiang; Xu, Guanghua; Zhang, Qing; Tse, Peter W; Tan, Haihui

    2016-01-01

    Lamb wave technique has been widely used in non-destructive evaluation (NDE) and structural health monitoring (SHM). However, due to the multi-mode characteristics and dispersive nature, Lamb wave propagation behavior is much more complex than that of bulk waves. Numerous numerical simulations on Lamb wave propagation have been conducted to study its physical principles. However, few quantitative studies on evaluating the accuracy of these numerical simulations were reported. In this paper, a method based on cross correlation analysis for quantitatively evaluating the simulation accuracy of time-transient Lamb waves propagation is proposed. Two kinds of error, affecting the position and shape accuracies are firstly identified. Consequently, two quantitative indices, i.e., the GVE (group velocity error) and MACCC (maximum absolute value of cross correlation coefficient) derived from cross correlation analysis between a simulated signal and a reference waveform, are proposed to assess the position and shape errors of the simulated signal. In this way, the simulation accuracy on the position and shape is quantitatively evaluated. In order to apply this proposed method to select appropriate element size and time step, a specialized 2D-FEM program combined with the proposed method is developed. Then, the proper element size considering different element types and time step considering different time integration schemes are selected. These results proved that the proposed method is feasible and effective, and can be used as an efficient tool for quantitatively evaluating and verifying the simulation accuracy of time-transient Lamb wave propagation.

  10. Decentralizing Statistical Accuracy Control Responsibility to the Ship Production Workforce (The National Shipbuilding Research Program)

    DTIC Science & Technology

    1987-01-01

    Fernando Ponce, Luis Torres, Al Vasquez, Ray Johnson; (standing) Dave Voigt, Sr., Joe Escar. cega, Lou Mansfield, Jim Elkins, Ted Mc- Callum, Minh...TRADES COUNCIL VALLEJO , CA Decentralization of Statistical Accuracy Control. Although variations of the Statistical Accuracy Con- trol process employed...NO. 3 SUBMITTED BY J. B. ‘HANK’ GERLACH, PRODUCTIVITY MANAGER, MARE ISLAND NAVAL SHIPYARD, VALLEJO , CA The authors and the National Steel and

  11. Note: electronic circuit for two-way time transfer via a single coaxial cable with picosecond accuracy and precision.

    PubMed

    Prochazka, Ivan; Kodet, Jan; Panek, Petr

    2012-11-01

    We have designed, constructed, and tested the overall performance of the electronic circuit for the two-way time transfer between two timing devices over modest distances with sub-picosecond precision and a systematic error of a few picoseconds. The concept of the electronic circuit enables to carry out time tagging of pulses of interest in parallel to the comparison of the time scales of these timing devices. The key timing parameters of the circuit are: temperature change of the delay is below 100 fs/K, timing stability time deviation better than 8 fs for averaging time from minutes to hours, sub-picosecond time transfer precision, and a few picoseconds time transfer accuracy.

  12. Real-time, high-accuracy 3D imaging and shape measurement.

    PubMed

    Nguyen, Hieu; Nguyen, Dung; Wang, Zhaoyang; Kieu, Hien; Le, Minh

    2015-01-01

    In spite of the recent advances in 3D shape measurement and geometry reconstruction, simultaneously achieving fast-speed and high-accuracy performance remains a big challenge in practice. In this paper, a 3D imaging and shape measurement system is presented to tackle such a challenge. The fringe-projection-profilometry-based system employs a number of advanced approaches, such as: composition of phase-shifted fringe patterns, externally triggered synchronization of system components, generalized system setup, ultrafast phase-unwrapping algorithm, flexible system calibration method, robust gamma correction scheme, multithread computation and processing, and graphics-processing-unit-based image display. Experiments have shown that the proposed system can acquire and display high-quality 3D reconstructed images and/or video stream at a speed of 45 frames per second with relative accuracy of 0.04% or at a reduced speed of 22.5 frames per second with enhanced accuracy of 0.01%. The 3D imaging and shape measurement system shows great promise of satisfying the ever-increasing demands of scientific and engineering applications.

  13. Limitations and strategies to improve measurement accuracy in differential pulse-width pair Brillouin optical time-domain analysis sensing.

    PubMed

    Minardo, Aldo; Bernini, Romeo; Zeni, Luigi

    2013-05-01

    In this work, we analyze the effects of Brillouin gain and Brillouin frequency drifts on the accuracy of the differential pulse-width pair Brillouin optical time-domain analysis (DPP-BOTDA). In particular, we demonstrate numerically that the differential gain is highly sensitive to variations in the Brillouin gain and/or Brillouin shift occurring during the acquisition process, especially when operating with a small pulse pair duration difference. We also propose and demonstrate experimentally a method to compensate for these drifts and consequently improve measurement accuracy.

  14. Evaluation of the accuracy of BOTDA systems based on the phase spectral response.

    PubMed

    Lopez-Gil, Alexia; Soto, Marcelo A; Angulo-Vinuesa, Xabier; Dominguez-Lopez, Alejandro; Martin-Lopez, Sonia; Thévenaz, Luc; Gonzalez-Herraez, Miguel

    2016-07-25

    We evaluate the Brillouin frequency shift (BFS) determination error when utilizing the Brillouin phase spectrum (BPS) instead of the Brillouin gain spectrum (BGS) in BOTDA systems. Systems based on the BPS perform the determination of the BFS through a linear fit around the zero de-phase frequency region. An analytical expression of the error obtained in the BFS determination as a function of the different experimental parameters is provided and experimentally validated. The experimental results show a good agreement with the theoretical predictions as a function of the number of sampling points, signal-to-noise ratio (SNR) and Brillouin spectral linewidth. For an equal SNR and linewidth, the phase response only provides a better BFS estimation than the gain response when the fit is performed over a restricted frequency range around the center of the spectral profile. This may reduce the measurement time of specific BOTDA systems requiring a narrow frequency scanning. When the frequency scan covers most of the Brillouin spectral profile, gain and phase responses give very similar estimations of the BFS and the BPS offers no crucial benefit.

  15. Method and apparatus for measuring response time

    DOEpatents

    Johanson, Edward W.; August, Charles

    1985-01-01

    A method of measuring the response time of an electrical instrument which generates an output signal in response to the application of a specified input, wherein the output signal varies as a function of time and when subjected to a step input approaches a steady-state value, comprises the steps of: (a) applying a step input of predetermined value to the electrical instrument to generate an output signal; (b) simultaneously starting a timer; (c) comparing the output signal to a reference signal to generate a stop signal when the output signal is substantially equal to the reference signal, the reference signal being a specified percentage of the steady-state value of the output signal corresponding to the predetermined value of the step input; and (d) applying the stop signal when generated to stop the timer.

  16. Method and apparatus for measuring response time

    DOEpatents

    Johanson, E.W.; August, C.

    1983-08-11

    A method of measuring the response time of an electrical instrument which generates an output signal in response to the application of a specified input, wherein the output signal varies as a function of time and when subjected to a step input approaches a steady-state value, comprises the steps of: (a) applying a step input of predetermined value to the electrical instrument to generate an output signal; (b) simultaneously starting a timer; (c) comparing the output signal to a reference signal to generate a stop signal when the output signal is substantially equal to the reference signal, the reference signal being a specified percentage of the steady-state value of the output signal corresponding to the predetermined value of the step input; and (d) applying the stop signal when generated to stop the timer.

  17. Binocular summation and peripheral visual response time

    NASA Technical Reports Server (NTRS)

    Gilliland, K.; Haines, R. F.

    1975-01-01

    Six males were administered a peripheral visual response time test to the onset of brief small stimuli imaged in 10-deg arc separation intervals across the dark adapted horizontal retinal meridian under both binocular and monocular viewing conditions. This was done in an attempt to verify the existence of peripheral binocular summation using a response time measure. The results indicated that from 50-deg arc right to 50-deg arc left of the line of sight binocular summation is a reasonable explanation for the significantly faster binocular data. The stimulus position by viewing eye interaction was also significant. A discussion of these and other analyses is presented along with a review of related literature.

  18. Response time correlations for platinum resistance thermometers

    NASA Technical Reports Server (NTRS)

    Pandey, D. K.; Ash, R. L.; Dillon-Townes, L. A.

    1985-01-01

    The 'plunge method' recommended by ASTM has been used to determine the time constant of 100-ohm platinum resistance thermometers (PRT) considered for use in the National Transonic Facility. It is shown that the response time of ventilated PRT can be correlated with the reciprocal of the heat transfer coefficient in a given field. Universal correlations are established for the 100- and 1000-ohm PRT with uncertainties of 20 and 30 percent, respectively. The correlations are found to be consistent with the uncertainty involved in heat transfer correlations available in the literature and are recommended for use in flowing liquids and gases.

  19. RTbox: a device for highly accurate response time measurements.

    PubMed

    Li, Xiangrui; Liang, Zhen; Kleiner, Mario; Lu, Zhong-Lin

    2010-02-01

    Although computer keyboards and mice are frequently used in measuring response times (RTs), the accuracy of these measurements is quite low. Specialized RT collection devices must be used to obtain more accurate measurements. However, all the existing devices have some shortcomings. We have developed and implemented a new, commercially available device, the RTbox, for highly accurate RT measurements. The RTbox has its own microprocessor and high-resolution clock. It can record the identities and timing of button events with high accuracy, unaffected by potential timing uncertainty or biases during data transmission and processing in the host computer. It stores button events until the host computer chooses to retrieve them. The asynchronous storage greatly simplifies the design of user programs. The RTbox can also receive and record external signals as triggers and can measure RTs with respect to external events. The internal clock of the RTbox can be synchronized with the computer clock, so the device can be used without external triggers. A simple USB connection is sufficient to integrate the RTbox with any standard computer and operating system.

  20. Regulating emotions uniquely modifies reaction time, rate of force production, and accuracy of a goal-directed motor action.

    PubMed

    Beatty, Garrett F; Fawver, Bradley; Hancock, Gabriella M; Janelle, Christopher M

    2014-02-01

    We investigated how emotion regulation (ER) strategies influence the execution of a memory guided, ballistic pinch grip. Participants (N=33) employed ER strategies (expressive suppression, emotional expression, and attentional deployment) while viewing emotional stimuli (IAPS images). Upon stimulus offset, participants produced a targeted pinch force aimed at 10% of their maximum voluntary contraction. Performance measures included reaction time (RT), rate of force production, and performance accuracy. As hypothesized, attentional deployment resulted in the slowest RT, largest rate of force production, and poorest performance accuracy. In contrast, expressive suppression reduced the rate of force production and increased performance accuracy relative to emotional expression and attentional deployment. Findings provide evidence that emotion regulation strategies uniquely influence human movement. Future work should further delineate the interacting role that emotion regulation strategies have in modulating both affective experience and motor performance.

  1. The effect of pouring time on the dimensional accuracy of casts made from different irreversible hydrocolloid impression materials

    PubMed Central

    Wadhwa, Supneet Singh; Mehta, Richa; Duggal, Nidhi; Vasudeva, Kamlesh

    2013-01-01

    Aims and Objectives: To determine the time dependent accuracy of casts made from three different irreversible hydrocolloids. Materials and Methods: The effect of delayed pouring on the accuracy of three different irreversible hydrocolloid impression materials – Regular set CA 37(Cavex, The Netherlands), regular set chromatic (Jeltrate, Dentsply), and fast set (Hydrogum soft, Zhermack Clinical) was investigated. A brass master die that contained two identical posts simulating two complete crown-tapered abutment preparations with reference grooves served as a standardized master model. A total of 120 impressions were made using specially prepared stock-perforated brass tray with 40 impressions of each material. The impressions were further sub-grouped according to four different storage time intervals: 0 min (immediately), 12 min, 30 min, and 1 h. The impressions were stored at room temperature in a zip-lock plastic bag. Interabutment and intraabutment distances were measured in the recovered stone dies (Type IV, Kalrock) using a profile projector with an accuracy of 0.001 mm. The data so obtained was analyzed statistically. Results: Results of this study showed no statistically significant differences in the accuracy of casts obtained at different time intervals. Conclusion: Because it is not always possible to pour the impression immediately in routine clinical practice, all irreversible hydrocolloid materials studied could be stored in a zip-lock plastic bag for upto 1 h without any significant distortion. PMID:24124296

  2. Tracking Accuracy of a Real-Time Fiducial Tracking System for Patient Positioning and Monitoring in Radiation Therapy

    SciTech Connect

    Shchory, Tal; Schifter, Dan; Lichtman, Rinat; Neustadter, David; Corn, Benjamin W.

    2010-11-15

    Purpose: In radiation therapy there is a need to accurately know the location of the target in real time. A novel radioactive tracking technology has been developed to answer this need. The technology consists of a radioactive implanted fiducial marker designed to minimize migration and a linac mounted tracking device. This study measured the static and dynamic accuracy of the new tracking technology in a clinical radiation therapy environment. Methods and Materials: The tracking device was installed on the linac gantry. The radioactive marker was located in a tissue equivalent phantom. Marker location was measured simultaneously by the radioactive tracking system and by a Microscribe G2 coordinate measuring machine (certified spatial accuracy of 0.38 mm). Localization consistency throughout a volume and absolute accuracy in the Fixed coordinate system were measured at multiple gantry angles over volumes of at least 10 cm in diameter centered at isocenter. Dynamic accuracy was measured with the marker located inside a breathing phantom. Results: The mean consistency for the static source was 0.58 mm throughout the tested region at all measured gantry angles. The mean absolute position error in the Fixed coordinate system for all gantry angles was 0.97 mm. The mean real-time tracking error for the dynamic source within the breathing phantom was less than 1 mm. Conclusions: This novel radioactive tracking technology has the potential to be useful in accurate target localization and real-time monitoring for radiation therapy.

  3. The Accuracy of Computer-Assisted Feedback and Students' Responses to It

    ERIC Educational Resources Information Center

    Lavolette, Elizabeth; Polio, Charlene; Kahng, Jimin

    2015-01-01

    Various researchers in second language acquisition have argued for the effectiveness of immediate rather than delayed feedback. In writing, truly immediate feedback is impractical, but computer-assisted feedback provides a quick way of providing feedback that also reduces the teacher's workload. We explored the accuracy of feedback from…

  4. The accuracy of simulated indoor time trials utilizing a CompuTrainer and GPS data.

    PubMed

    Peveler, Willard W

    2013-10-01

    The CompuTrainer is commonly used to measure cycling time trial performance in a laboratory setting. Previous research has demonstrated that the CompuTrainer tends toward underestimating power at higher workloads but provides reliable measures. The extent to which the CompuTrainer is capable of simulating outdoor time trials in a laboratory setting has yet to be examined. The purpose of this study was to examine the validity of replicating an outdoor time trial course indoors by comparing completion times between the actual time trial course and the replicated outdoor time trial course on the CompuTrainer. A global positioning system was used to collect data points along a local outdoor time trial course. Data were then downloaded and converted into a time trial course for the CompuTrainer. Eleven recreational to highly trained cyclists participated in this study. To participate in this study, subjects had to have completed a minimum of 2 of the local Cleves time trial races. Subjects completed 2 simulated indoor time trials on the CompuTrainer. Mean finishing times for the mean indoor performance trial (34.58 ± 8.63 minutes) were significantly slower in relation to the mean outdoor performance time (26.24 ± 3.23 minutes). Cyclists' finish times increased (performance decreased) by 24% on the indoor time trials in relation to the mean outdoor times. There were no significant differences between CompuTrainer trial 1 (34.77 ± 8.54 minutes) and CompuTrainer trial 1 (34.37 ± 8.76 minutes). Because of the significant differences in times between the indoor and outdoor time trials, meaningful comparisons of performance times cannot be made between the two. However, there were no significant differences found between the 2 CompuTrainer trials, and therefore the CompuTrainer can still be recommended for laboratory testing between trials.

  5. Unstructured grids in 3D and 4D for a time-dependent interface in front tracking with improved accuracy

    SciTech Connect

    Glimm, J.; Grove, J. W.; Li, X. L.; Li, Y.; Xu, Z.

    2002-01-01

    Front tracking traces the dynamic evolution of an interface separating differnt materials or fluid components. In this paper, they describe three types of the grid generation methods used in the front tracking method. One is the unstructured surface grid. The second is a structured grid-based reconstruction method. The third is a time-space grid, also grid based, for a conservative tracking algorithm with improved accuracy.

  6. Accuracy Study of the Space-Time CE/SE Method for Computational Aeroacoustics Problems Involving Shock Waves

    NASA Technical Reports Server (NTRS)

    Wang, Xiao Yen; Chang, Sin-Chung; Jorgenson, Philip C. E.

    1999-01-01

    The space-time conservation element and solution element(CE/SE) method is used to study the sound-shock interaction problem. The order of accuracy of numerical schemes is investigated. The linear model problem.govemed by the 1-D scalar convection equation, sound-shock interaction problem governed by the 1-D Euler equations, and the 1-D shock-tube problem which involves moving shock waves and contact surfaces are solved to investigate the order of accuracy of numerical schemes. It is concluded that the accuracy of the CE/SE numerical scheme with designed 2nd-order accuracy becomes 1st order when a moving shock wave exists. However, the absolute error in the CE/SE solution downstream of the shock wave is on the same order as that obtained using a fourth-order accurate essentially nonoscillatory (ENO) scheme. No special techniques are used for either high-frequency low-amplitude waves or shock waves.

  7. Investigation of the effects of storage time on the dimensional accuracy of impression materials using cone beam computed tomography

    PubMed Central

    2016-01-01

    PURPOSE The storage conditions of impressions affect the dimensional accuracy of the impression materials. The aim of the study was to assess the effects of storage time on dimensional accuracy of five different impression materials by cone beam computed tomography (CBCT). MATERIALS AND METHODS Polyether (Impregum), hydrocolloid (Hydrogum and Alginoplast), and silicone (Zetaflow and Honigum) impression materials were used for impressions taken from an acrylic master model. The impressions were poured and subjected to four different storage times: immediate use, and 1, 3, and 5 days of storage. Line 1 (between right and left first molar mesiobuccal cusp tips) and Line 2 (between right and left canine tips) were measured on a CBCT scanned model, and time dependent mean differences were analyzed by two-way univariate and Duncan's test (α=.05). RESULTS For Line 1, the total mean difference of Impregum and Hydrogum were statistically different from Alginoplast (P<.05), while Zetaflow and Honigum had smaller discrepancies. Alginoplast resulted in more difference than the other impressions (P<.05). For Line 2, the total mean difference of Impregum was statistically different from the other impressions. Significant differences were observed in Line 1 and Line 2 for the different storage periods (P<.05). CONCLUSION The dimensional accuracy of impression material is clinically acceptable if the impression material is stored in suitable conditions. PMID:27826388

  8. Accuracy of real-time optoacoustic temperature determination during retinal photocoagulation

    NASA Astrophysics Data System (ADS)

    Baade, A.; Schlott, K.; Luft, S.; Ptaszynski, L.; Bever, M.; Birngruber, R.; Brinkmann, R.

    2011-07-01

    Retinal photocoagulation is an established treatment for various retinal diseases. The temperature development during a treatment can be monitored by applying short laser pulses in addition to the treatment laser light. The laser pulses induce optoacoustic pressure waves that can be detected at the cornea. Aim of this work is the investigation of the accuracy of the determined temperatures during a treatment. To calibrate the temperature dependency of the measured pressure, whole enucleated porcine eyes were heated using an infrared laser beam, while probing the retina optoacoustically. The temperatures and the optoacoustic pressure waves were measured simultaneously using thermocouples and a piezoelectric element, respectively. From the deviation of the individual measurements an error of less than 15% in the calibration regime between 37 °C to 55 °C was found. Furthermore, the spatial and temporal temperature course was investigated. Calculations were performed to simulate the temporal and spatial temperature development during photocoagulation. A theoretical model to determine the peak temperature of the irradiated tissue from the mean temperature measured by optoacoustics was developed. The validity of the model was experimentally examined by heating the retina of porcine eyes with a laser beam diameter of 500 μm while successively measuring the temperature optoacoustically with a probe beam diameter of 500 μm and 100 μm at the center of the heated area, respectively. The deviation of the theoretical model and the experimental results were found to be less than 7%.

  9. Accuracy and Variability of Isochronous Rhythmic Timing across Motor Systems in Stuttering versus Nonstuttering Individuals.

    ERIC Educational Resources Information Center

    Max, Ludo; Yudman, Elana M.

    2003-01-01

    This study with 10 adults who stutter and 10 nonstuttering controls completed speech, orofacial nonspeech, and finger isochronous rhythmic timing tasks to investigate the role of timing in stuttering. Findings extend growing evidence that stuttering individuals do not differ from nonstuttering individuals in the ability to generate temporal…

  10. Meta-analysis of time perception and temporal processing in schizophrenia: Differential effects on precision and accuracy.

    PubMed

    Thoenes, Sven; Oberfeld, Daniel

    2017-03-29

    Numerous studies have reported that time perception and temporal processing are impaired in schizophrenia. In a meta-analytical review, we differentiate between time perception (judgments of time intervals) and basic temporal processing (e.g., judgments of temporal order) as well as between effects on accuracy (deviation of estimates from the veridical value) and precision (variability of judgments). In a meta-regression approach, we also included the specific tasks and the different time interval ranges as covariates. We considered 68 publications of the past 65years, and meta-analyzed data from 957 patients with schizophrenia and 1060 healthy control participants. Independent of tasks and interval durations, our results demonstrate that time perception and basic temporal processing are less precise (more variable) in patients (Hedges' g>1.00), whereas effects of schizophrenia on accuracy of time perception are rather small and task-dependent. Our review also shows that several aspects, e.g., potential influences of medication, have not yet been investigated in sufficient detail. In conclusion, the results are in accordance with theoretical assumptions and the notion of a more variable internal clock in patients with schizophrenia, but not with a strong effect of schizophrenia on clock speed. The impairment of temporal precision, however, may also be clock-unspecific as part of a general cognitive deficiency in schizophrenia.

  11. Stroke savvy. The accuracy of EMS-reported last known normal times.

    PubMed

    Wesley, Keith; Wesley, Karen

    2014-09-01

    We collected EMS-reported "last known normal" (LKN) times for patients brought to the ED with suspected acute stroke and calculated the absolute difference between the neurologist-determined and EMS-reported LKN times (deltaLKN). We determined the rate of inappropriate IV tissue plasminogen activator (tPA) use if the EMS-reported times were used instead of the neurologist-determined times. Of 251 patients, mean and median deltaLKN were 28 and 0 minutes, respectively. deltaLKN was < 15 minutes in 91% of the entire group and < 15 minutes in 80% of patients with a diagnosis of stroke. Of patients who received IV tPA, none would've been incorrectly excluded from IV tPA if the EMS LKN time had been used. Conversely, of patients who didn't receive IV tPA, 6% would have been incorrectly included for IV tPA consideration had the EMS time been used. In patients with wake-up stroke symptoms, EMS underestimated LKN times by an average of 208 minutes. All of the potentially incorrectly included patients would've been wake-up strokes.

  12. Association Between Time Spent Interpreting, Level of Confidence and Accuracy of Screening Mammography

    PubMed Central

    Carney, Patricia A.; Bogart, Andy; Geller, Berta M.; Haneuse, Sebastian; Kerlikowske, Karla; Buist, Diana SM; Smith, Robert; Rosenberg, Robert; Yankaskas, Bonnie C.; Onega, Tracy; Miglioretti, Diana L.

    2013-01-01

    Purpose To examine the effect of time spent viewing images and level of confidence on a screening mammography test set on interpretive performance. Materials and Methods Radiologists from six mammography registries participated in the study and were randomized to interpret one of four test sets and complete 12 survey questions. Each test set had 109 cases of digitized four-view screening film-screen mammograms with prior comparison screening views. Viewing time for each case was defined as the cumulative time spent viewing all mammographic images before recording which visible feature, if any, was the “most significant finding”. Log-linear regression fit via GEE was used to test the effect of viewing time and level of confidence in the interpretation on test set sensitivity and false-positive rate. Results 119 radiologists completed a test set and contributed data on 11,484 interpretations. Radiologists spent more time viewing cases that had significant findings or for which they had less confidence in interpretation. Each additional minute of viewing time increased the probability of a true positive interpretation among cancer cases by 1.12 (95% CI: 1.06, 1.19, p<0.001), regardless of confidence in the assessment. Among radiologists who were ‘very confident’ in their assessment, each additional minute of viewing time increased the adjusted risk of a false positive interpretation among non-cancer cases by 1.42 (95% CI 1.21, 1.68), and this viewing-time effect diminished with decreasing confidence. Conclusions Longer interpretation times and higher levels of confidence in the interpretation are both associated with higher sensitivity and false positive rates in mammography screening. PMID:22451568

  13. Accuracy study of time delay estimation techniques in laser pulse ranger

    NASA Astrophysics Data System (ADS)

    Yang, Jinliang; Wang, Xingshu; Gao, Yang

    2013-12-01

    Time-of-flight measurement by using laser pulses is an alternative method in laser range finding and laser scanning, the echo pulses originating from backscattering of the emitted laser pulse on targets is detected by optical receiver. The distance of target can be obtained by measuring the round-trip time. Time-of-arrival estimation may be based on schemes such as constant-fraction discriminator (CFD) in analog electronics. In contrast, as sampled signals are available, time delay estimation may be based on schemes like direct cross-correlation function (CCF) and average square difference function (ASDF) in digital electronics. By the way, constant-fraction discriminator can also be used in digital electronics. All this three methods are analyzed and compared with each other. It is shown that estimators based on CCF and ASDF are more precise than conventional CFD based estimator.

  14. Two- and three-dimensional accuracy of dental impression materials: effects of storage time and moisture contamination.

    PubMed

    Chandran, Deepa T; Jagger, Daryll C; Jagger, Robert G; Barbour, Michele E

    2010-01-01

    Dental impression materials are used to create an inverse replica of the dental hard and soft tissues, and are used in processes such as the fabrication of crowns and bridges. The accuracy and dimensional stability of impression materials are of paramount importance to the accuracy of fit of the resultant prosthesis. Conventional methods for assessing the dimensional stability of impression materials are two-dimensional (2D), and assess shrinkage or expansion between selected fixed points on the impression. In this study, dimensional changes in four impression materials were assessed using an established 2D and an experimental three-dimensional (3D) technique. The former involved measurement of the distance between reference points on the impression; the latter a contact scanning method for producing a computer map of the impression surface showing localised expansion, contraction and warpage. Dimensional changes were assessed as a function of storage times and moisture contamination comparable to that found in clinical situations. It was evident that dimensional changes observed using the 3D technique were not always apparent using the 2D technique, and that the former offers certain advantages in terms of assessing dimensional accuracy and predictability of impression methods. There are, however, drawbacks associated with 3D techniques such as the more time-consuming nature of the data acquisition and difficulty in statistically analysing the data.

  15. Movement imagery for speech in healthy women: influences on articulation accuracy and fluidity, imagery times, and expectations of success.

    PubMed

    Mantie-Kozlowski, Alana; Netsell, Ronald; Daniel, Todd

    2012-12-01

    The use of movement imagery in speech performance has received less attention than it has in many other professional disciplines. 30 healthy monolingual native English speakers participated in this within-subjects study. Participants' speech accuracy and fluidity was compared when they used movement imagery and when they did not. The timing of imagery and articulation were compared using a chronometric paradigm. Participants' expectations of improvement when using movement imagery for speech were compared to their actual performance. The results from this study support the use of movement imagery for speech with a single imaging event for the purpose of improving speech fluidity, but not for improving articulation accuracy. The chronometric system as a tool for monitoring adherence to the movement imagery protocol for speech proved valuable. Finally, while estimation inflation has been reported by some using movement imagery techniques, this was not the case for the participants of this study.

  16. A novel mask proximity correction software combining accuracy and reduced writing time for the manufacturing of advanced photomasks

    NASA Astrophysics Data System (ADS)

    Schiavone, Patrick; Martin, Luc; Browning, Clyde; Farys, Vincent; Sundermann, Frank; Narukawa, Shogo; Takikawa, Tadahiko; Hayashi, Naoya

    2012-06-01

    The new generations of photomasks are seen to bring more and more challenges to the mask manufacturer. Maskshops face two conflicting requirements, namely improving pattern fidelity and reducing or at least maintaining acceptable writing time. These requirements are getting more and more challenging since pattern size continuously shrinks and data volumes continuously grows. Although the classical dose modulation Proximity Effect Correction is able to provide sufficient process control to the mainstream products, an increased number of published and wafer data show that the mask process is becoming a nonnegligible contributor to the 28nm technology yield. We will show in this paper that a novel approach of mask proximity effect correction is able to meet the dual challenge of the new generation of masks. Unlike the classical approach, the technique presented in this paper is based on a concurrent optimization of the dose and geometry of the fractured shots. Adding one more parameter allows providing the best possible compromise between accuracy and writing time since energy latitude can be taken into account as well. This solution is implemented in the Inscale software package from Aselta Nanographics. We have assessed the capability of this technology on several levels of a 28nm technology. On this set, the writing time has been reduced up to 25% without sacrificing the accuracy which at the same time has been improved significantly compared to the existing process. The experiments presented in the paper confirm that a versatile proximity effect correction strategy, combining dose and geometry modulation helps the users to tradeoff between resolution/accuracy and e-beam write time.

  17. Accuracy of patient's turnover time prediction using RFID technology in an academic ambulatory surgery center.

    PubMed

    Marchand-Maillet, Florence; Debes, Claire; Garnier, Fanny; Dufeu, Nicolas; Sciard, Didier; Beaussier, Marc

    2015-02-01

    Patients flow in outpatient surgical unit is a major issue with regards to resource utilization, overall case load and patient satisfaction. An electronic Radio Frequency Identification Device (RFID) was used to document the overall time spent by the patients between their admission and discharge from the unit. The objective of this study was to evaluate how a RFID-based data collection system could provide an accurate prediction of the actual time for the patient to be discharged from the ambulatory surgical unit after surgery. This is an observational prospective evaluation carried out in an academic ambulatory surgery center (ASC). Data on length of stay at each step of the patient care, from admission to discharge, were recorded by a RFID device and analyzed according to the type of surgical procedure, the surgeon and the anesthetic technique. Based on these initial data (n = 1520), patients were scheduled in a sequential manner according to the expected duration of the previous case. The primary endpoint was the difference between actual and predicted time of discharge from the unit. A total of 414 consecutive patients were prospectively evaluated. One hundred seventy four patients (42%) were discharged at the predicted time ± 30 min. Only 24% were discharged behind predicted schedule. Using an automatic record of patient's length of stay would allow an accurate prediction of the discharge time according to the type of surgery, the surgeon and the anesthetic procedure.

  18. Boosting the accuracy and speed of quantum Monte Carlo: Size consistency and time step

    NASA Astrophysics Data System (ADS)

    Zen, Andrea; Sorella, Sandro; Gillan, Michael J.; Michaelides, Angelos; Alfè, Dario

    2016-06-01

    Diffusion Monte Carlo (DMC) simulations for fermions are becoming the standard for providing high-quality reference data in systems that are too large to be investigated via quantum chemical approaches. DMC with the fixed-node approximation relies on modifications of the Green's function to avoid singularities near the nodal surface of the trial wave function. Here we show that these modifications affect the DMC energies in a way that is not size consistent, resulting in large time-step errors. Building on the modifications of Umrigar et al. and DePasquale et al. we propose a simple Green's function modification that restores size consistency to large values of the time step, which substantially reduces time-step errors. This algorithm also yields remarkable speedups of up to two orders of magnitude in the calculation of molecule-molecule binding energies and crystal cohesive energies, thus extending the horizons of what is possible with DMC.

  19. Method and computer product to increase accuracy of time-based software verification for sensor networks

    DOEpatents

    Foo Kune, Denis [Saint Paul, MN; Mahadevan, Karthikeyan [Mountain View, CA

    2011-01-25

    A recursive verification protocol to reduce the time variance due to delays in the network by putting the subject node at most one hop from the verifier node provides for an efficient manner to test wireless sensor nodes. Since the software signatures are time based, recursive testing will give a much cleaner signal for positive verification of the software running on any one node in the sensor network. In this protocol, the main verifier checks its neighbor, who in turn checks its neighbor, and continuing this process until all nodes have been verified. This ensures minimum time delays for the software verification. Should a node fail the test, the software verification downstream is halted until an alternative path (one not including the failed node) is found. Utilizing techniques well known in the art, having a node tested twice, or not at all, can be avoided.

  20. Accuracy of PET rCBF measurements: Effect of transit time delay

    SciTech Connect

    Dhawan, V.; Conti, J.; Mernyk, M.; Jarden, J.; Rottenberg, D.A.

    1984-01-01

    Analytic expressions were derived for estimating the error in PET rCBF measurements associated with the time lag between brain and blood radioactivity (1) following 0-15 water injection and (2) during non-steady-state 0-15 CO/sub 2/ inhalation. This lag time reflects the physiological difference in arrival times of 0-15 activity at brain and radial arterial sampling site as well as the experimentally introduced resistance to flow offered by the arterial catheter/stopcock assembly. Multiple measurements of transit time delay were made in 2 patients using Rb-82. The arrival of radioactivity in the brain was detected by a pair of PET detectors operating in coincidence. The arrival of radioactivity at the radial arterial catheter was estimated from consecutive 5-sec blood samples (catheter flow rate 7-10 ml/min). Transit time delays varied between 1 and 8 sec. For non-steady-state 0-15 CO/sub 2//PET measurements, estimated errors in rCBF ranged from 0.02 to 30% for delays of 2-8 sec and scan lengths of 30-180 sec. In the range 20-100 ml/min/100 g, variations in rCBF only marginally affected these errors. Errors increased with scan length and with longer delays but decreased sharply with scan duration > 60 sec. For 30-180 sec scans, even larger errors are associated with the 0-15 water injection technique (peak blood activity at 10 sec): 1-60% for delays of 2-8 sec. A ''slow'' bolus peaking at 20 sec decreased the error by 40%. For the 0-15 water method it is essential to determine the transit time delay to within 2 sec if accurate flow measurements (error < 5%) are to be obtained from 40-60 sec scans.

  1. Response time correlations for platinum resistance thermometers in flowing fluids

    NASA Technical Reports Server (NTRS)

    Pandey, D. K.; Ash, R. L.

    1985-01-01

    The thermal response of two types of Platinum Resistance Thermometers (PRT's), which are being considered for use in the National Transonic Wind Tunnel Facility, were studied. Response time correlations for each PRT, in flowing water, oil and air, were established separately. A universal correlation, tau WOA = 2.0 + 1264, 9/h, for a Hy-Cal Sensor (with a reference resistance of 100 ohm) within an error of 20% was established while the universal correlation for the Rosemount Sensor (with a reference resistance of 1000 ohm), tau OA = 0.122 + 1105.6/h, was found with a maximum percentage error of 30%. The correlation for the Rosemount Sensor was based on air and oil data only which is certainly not sufficient to make a correlation applicable to every condition. Therefore, the correlation needs more data to be gathered in different fluids. Also, it is necessary to state that the calculation of the parameter, h, was based on the available heat transfer correlations, whose accuracies are already reported in literature uncertain within 20-30%. Therefore, the universal response constant correlations established here for the Hy-Cal and Rosemount sensors are consistent with the uncertainty in the input data and are recommended for future use in flowing liquids and gases.

  2. Repeating a Monologue under Increasing Time Pressure: Effects on Fluency, Complexity, and Accuracy

    ERIC Educational Resources Information Center

    Thai, Chau; Boers, Frank

    2016-01-01

    Studies have shown that learners' task performance improves when they have the opportunity to repeat the task. Conditions for task repetition vary, however. In the 4/3/2 activity, learners repeat a monologue under increasing time pressure. The purpose is to foster fluency, but it has been suggested in the literature that it also benefits other…

  3. There Is Time for Calculation in Speed Chess, and Calculation Accuracy Increases With Expertise.

    PubMed

    Chang, Yu-Hsuan A; Lane, David M

    2016-01-01

    The recognition-action theory of chess skill holds that expertise in chess is due primarily to the ability to recognize familiar patterns of pieces. Despite its widespread acclaim, empirical evidence for this theory is indirect. One source of indirect evidence is that there is a high correlation between speed chess and standard chess. Assuming that there is little or no time for calculation in speed chess, this high correlation implies that calculation is not the primary factor in standard chess. Two studies were conducted analyzing 100 games of speed chess. In Study 1, we examined the distributions of move times, and the key finding was that players often spent considerable time on a few moves. Moreover, stronger players were more likely than weaker players to do so. Study 2 examined skill differences in calculation by examining poor moves. The stronger players made proportionally fewer blunders (moves that a 2-ply search would have revealed to be errors). Overall, the poor moves made by the weaker players would have required a less extensive search to be revealed as poor moves than the poor moves made by the stronger players. Apparently, the stronger players are searching deeper and more accurately. These results are difficult to reconcile with the view that speed chess does not allow players time to calculate extensively and call into question the assertion that the high correlation between speed chess and standard chess supports recognition-action theory.

  4. A Comparison of the Accuracy of Discrete Event and Discrete Time

    DTIC Science & Technology

    2010-12-01

    over these places and may not be able to capture the rate at which the changes are occurring. In these circumstances the time step is too big . Finally...different sized quanta D. All solutions converged quickly to the neighborhood of the steady-state value of 1.0. Those for which the steady-state value was

  5. Response times from ensembles of accumulators

    PubMed Central

    Zandbelt, Bram; Purcell, Braden A.; Palmeri, Thomas J.; Logan, Gordon D.; Schall, Jeffrey D.

    2014-01-01

    Decision-making is explained by psychologists through stochastic accumulator models and by neurophysiologists through the activity of neurons believed to instantiate these models. We investigated an overlooked scaling problem: How does a response time (RT) that can be explained by a single model accumulator arise from numerous, redundant accumulator neurons, each of which individually appears to explain the variability of RT? We explored this scaling problem by developing a unique ensemble model of RT, called e pluribus unum, which embodies the well-known dictum “out of many, one.” We used the e pluribus unum model to analyze the RTs produced by ensembles of redundant, idiosyncratic stochastic accumulators under various termination mechanisms and accumulation rate correlations in computer simulations of ensembles of varying size. We found that predicted RT distributions are largely invariant to ensemble size if the accumulators share at least modestly correlated accumulation rates and RT is not governed by the most extreme accumulators. Under these regimes the termination times of individual accumulators was predictive of ensemble RT. We also found that the threshold measured on individual accumulators, corresponding to the firing rate of neurons measured at RT, can be invariant with RT but is equivalent to the specified model threshold only when the rate correlation is very high. PMID:24550315

  6. Time Efficiency and Diagnostic Accuracy of New Automated Myocardial Perfusion Analysis Software in 320-Row CT Cardiac Imaging

    PubMed Central

    Rief, Matthias; Stenzel, Fabian; Kranz, Anisha; Schlattmann, Peter

    2013-01-01

    Objective We aimed to evaluate the time efficiency and diagnostic accuracy of automated myocardial computed tomography perfusion (CTP) image analysis software. Materials and Methods 320-row CTP was performed in 30 patients, and analyses were conducted independently by three different blinded readers by the use of two recent software releases (version 4.6 and novel version 4.71GR001, Toshiba, Tokyo, Japan). Analysis times were compared, and automated epi- and endocardial contour detection was subjectively rated in five categories (excellent, good, fair, poor and very poor). As semi-quantitative perfusion parameters, myocardial attenuation and transmural perfusion ratio (TPR) were calculated for each myocardial segment and agreement was tested by using the intraclass correlation coefficient (ICC). Conventional coronary angiography served as reference standard. Results The analysis time was significantly reduced with the novel automated software version as compared with the former release (Reader 1: 43:08 ± 11:39 min vs. 09:47 ± 04:51 min, Reader 2: 42:07 ± 06:44 min vs. 09:42 ± 02:50 min and Reader 3: 21:38 ± 3:44 min vs. 07:34 ± 02:12 min; p < 0.001 for all). Epi- and endocardial contour detection for the novel software was rated to be significantly better (p < 0.001) than with the former software. ICCs demonstrated strong agreement (≥ 0.75) for myocardial attenuation in 93% and for TPR in 82%. Diagnostic accuracy for the two software versions was not significantly different (p = 0.169) as compared with conventional coronary angiography. Conclusion The novel automated CTP analysis software offers enhanced time efficiency with an improvement by a factor of about four, while maintaining diagnostic accuracy. PMID:23323027

  7. Comparison of Clinician Judgments and Measurements of Swallow Response Time: A Preliminary Report

    ERIC Educational Resources Information Center

    Karnell, Michael P.; Rogus, Nicole M.

    2005-01-01

    Practicing clinicians frequently offer judgments about aspects of swallowing physiology rather than performing actual measurements. Little is known about the accuracy of those judgments. The purpose of this preliminary study was to explore agreement of clinicians' judgments of pharyngeal swallow response time (PSRT) with temporal measurements of…

  8. Computer-assisted TPN calculations: time savings and improved accuracy associated with use of a minicomputer.

    PubMed

    Raehtz, K G; Walker, P C

    1988-09-01

    A pediatric TPN computer program, written in Cobol 74 machine language, was developed for use on a minicomputer system. The program calculates the volume of each ingredient needed to prepare a pediatric TPN solution, generates a recipe work card and labels, calculates clinical monitoring information for each patient and develops a clinical monitoring profile for the pharmacist to use in monitoring parenteral nutrition therapy. Use of the program resulted in a significant reduction (71%) in the time needed ot complete TPN calculations. Significant decreases in calculation and labeling errors were also realized.

  9. 28 CFR 20.37 - Responsibility for accuracy, completeness, currency, and integrity.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... INFORMATION SYSTEMS Federal Systems and Exchange of Criminal History Record Information § 20.37 Responsibility... justice agency contributing data to the III System and the FIRS to assure that information on...

  10. 28 CFR 20.37 - Responsibility for accuracy, completeness, currency, and integrity.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... INFORMATION SYSTEMS Federal Systems and Exchange of Criminal History Record Information § 20.37 Responsibility... justice agency contributing data to the III System and the FIRS to assure that information on...

  11. 28 CFR 20.37 - Responsibility for accuracy, completeness, currency, and integrity.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... INFORMATION SYSTEMS Federal Systems and Exchange of Criminal History Record Information § 20.37 Responsibility... justice agency contributing data to the III System and the FIRS to assure that information on...

  12. 28 CFR 20.37 - Responsibility for accuracy, completeness, currency, and integrity.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... INFORMATION SYSTEMS Federal Systems and Exchange of Criminal History Record Information § 20.37 Responsibility... justice agency contributing data to the III System and the FIRS to assure that information on...

  13. 28 CFR 20.37 - Responsibility for accuracy, completeness, currency, and integrity.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... INFORMATION SYSTEMS Federal Systems and Exchange of Criminal History Record Information § 20.37 Responsibility... justice agency contributing data to the III System and the FIRS to assure that information on...

  14. Accuracy and optimal timing of activity measurements in estimating the absorbed dose of radioiodine in the treatment of Graves' disease

    NASA Astrophysics Data System (ADS)

    Merrill, S.; Horowitz, J.; Traino, A. C.; Chipkin, S. R.; Hollot, C. V.; Chait, Y.

    2011-02-01

    Calculation of the therapeutic activity of radioiodine 131I for individualized dosimetry in the treatment of Graves' disease requires an accurate estimate of the thyroid absorbed radiation dose based on a tracer activity administration of 131I. Common approaches (Marinelli-Quimby formula, MIRD algorithm) use, respectively, the effective half-life of radioiodine in the thyroid and the time-integrated activity. Many physicians perform one, two, or at most three tracer dose activity measurements at various times and calculate the required therapeutic activity by ad hoc methods. In this paper, we study the accuracy of estimates of four 'target variables': time-integrated activity coefficient, time of maximum activity, maximum activity, and effective half-life in the gland. Clinical data from 41 patients who underwent 131I therapy for Graves' disease at the University Hospital in Pisa, Italy, are used for analysis. The radioiodine kinetics are described using a nonlinear mixed-effects model. The distributions of the target variables in the patient population are characterized. Using minimum root mean squared error as the criterion, optimal 1-, 2-, and 3-point sampling schedules are determined for estimation of the target variables, and probabilistic bounds are given for the errors under the optimal times. An algorithm is developed for computing the optimal 1-, 2-, and 3-point sampling schedules for the target variables. This algorithm is implemented in a freely available software tool. Taking into consideration 131I effective half-life in the thyroid and measurement noise, the optimal 1-point time for time-integrated activity coefficient is a measurement 1 week following the tracer dose. Additional measurements give only a slight improvement in accuracy.

  15. "Right Time, Right Place" Health Communication on Twitter: Value and Accuracy of Location Information

    PubMed Central

    Burton, Scott H; Tanner, Kesler W; West, Joshua H; Barnes, Michael D

    2012-01-01

    Background Twitter provides various types of location data, including exact Global Positioning System (GPS) coordinates, which could be used for infoveillance and infodemiology (ie, the study and monitoring of online health information), health communication, and interventions. Despite its potential, Twitter location information is not well understood or well documented, limiting its public health utility. Objective The objective of this study was to document and describe the various types of location information available in Twitter. The different types of location data that can be ascertained from Twitter users are described. This information is key to informing future research on the availability, usability, and limitations of such location data. Methods Location data was gathered directly from Twitter using its application programming interface (API). The maximum tweets allowed by Twitter were gathered (1% of the total tweets) over 2 separate weeks in October and November 2011. The final dataset consisted of 23.8 million tweets from 9.5 million unique users. Frequencies for each of the location options were calculated to determine the prevalence of the various location data options by region of the world, time zone, and state within the United States. Data from the US Census Bureau were also compiled to determine population proportions in each state, and Pearson correlation coefficients were used to compare each state’s population with the number of Twitter users who enable the GPS location option. Results The GPS location data could be ascertained for 2.02% of tweets and 2.70% of unique users. Using a simple text-matching approach, 17.13% of user profiles in the 4 continental US time zones were able to be used to determine the user’s city and state. Agreement between GPS data and data from the text-matching approach was high (87.69%). Furthermore, there was a significant correlation between the number of Twitter users per state and the 2010 US Census state

  16. A Flexible Latent Trait Model for Response Times in Tests

    ERIC Educational Resources Information Center

    Ranger, Jochen; Kuhn, Jorg-Tobias

    2012-01-01

    Latent trait models for response times in tests have become popular recently. One challenge for response time modeling is the fact that the distribution of response times can differ considerably even in similar tests. In order to reduce the need for tailor-made models, a model is proposed that unifies two popular approaches to response time…

  17. Medication Harmony: A Framework to Save Time, Improve Accuracy and Increase Patient Activation

    PubMed Central

    Pandolfe, Frank; Crotty, Bradley H; Safran, Charles

    2016-01-01

    Incompletely reconciled medication lists contribute to prescribing errors and adverse drug events. Providers expend time and effort at every point of patient contact attempting to curate a best possible medication list, and yet often the list is incomplete or inaccurate. We propose a framework that builds upon the existing infrastructure of a health information exchange (HIE), centralizes data and encourages patient activation. The solution is a constantly accessible, singular, patient-adjudicated medication list that incorporates useful information and features into the list itself. We aim to decrease medication errors across transitions of care, increase awareness of potential drug-drug interactions, improve patient knowledge and self-efficacy regarding medications, decrease polypharmacy, improve prescribing safety and ultimately decrease cost to the health-care system. PMID:28269955

  18. A time projection chamber for high accuracy and precision fission cross-section measurements

    DOE PAGES

    Heffner, M.; Asner, D. M.; Baker, R. G.; ...

    2014-05-22

    The fission Time Projection Chamber (fissionTPC) is a compact (15 cm diameter) two-chamber MICROMEGAS TPC designed to make precision cross-section measurements of neutron-induced fission. The actinide targets are placed on the central cathode and irradiated with a neutron beam that passes axially through the TPC inducing fission in the target. The 4π acceptance for fission fragments and complete charged particle track reconstruction are powerful features of the fissionTPC which will be used to measure fission cross-sections and examine the associated systematic errors. This study provides a detailed description of the design requirements, the design solutions, and the initial performance ofmore » the fissionTPC.« less

  19. A time projection chamber for high accuracy and precision fission cross-section measurements

    SciTech Connect

    Heffner, M.; Asner, D. M.; Baker, R. G.; Baker, J.; Barrett, S.; Brune, C.; Bundgaard, J.; Burgett, E.; Carter, D.; Cunningham, M.; Deaven, J.; Duke, D. L.; Greife, U.; Grimes, S.; Hager, U.; Hertel, N.; Hill, T.; Isenhower, D.; Jewell, K.; King, J.; Klay, J. L.; Kleinrath, V.; Kornilov, N.; Kudo, R.; Laptev, A. B.; Leonard, M.; Loveland, W.; Massey, T. N.; McGrath, C.; Meharchand, R.; Montoya, L.; Pickle, N.; Qu, H.; Riot, V.; Ruz, J.; Sangiorgio, S.; Seilhan, B.; Sharma, S.; Snyder, L.; Stave, S.; Tatishvili, G.; Thornton, R. T.; Tovesson, F.; Towell, D.; Towell, R. S.; Watson, S.; Wendt, B.; Wood, L.; Yao, L.

    2014-05-22

    The fission Time Projection Chamber (fissionTPC) is a compact (15 cm diameter) two-chamber MICROMEGAS TPC designed to make precision cross-section measurements of neutron-induced fission. The actinide targets are placed on the central cathode and irradiated with a neutron beam that passes axially through the TPC inducing fission in the target. The 4π acceptance for fission fragments and complete charged particle track reconstruction are powerful features of the fissionTPC which will be used to measure fission cross-sections and examine the associated systematic errors. This study provides a detailed description of the design requirements, the design solutions, and the initial performance of the fissionTPC.

  20. Medication Harmony: A Framework to Save Time, Improve Accuracy and Increase Patient Activation.

    PubMed

    Pandolfe, Frank; Crotty, Bradley H; Safran, Charles

    2016-01-01

    Incompletely reconciled medication lists contribute to prescribing errors and adverse drug events. Providers expend time and effort at every point of patient contact attempting to curate a best possible medication list, and yet often the list is incomplete or inaccurate. We propose a framework that builds upon the existing infrastructure of a health information exchange (HIE), centralizes data and encourages patient activation. The solution is a constantly accessible, singular, patient-adjudicated medication list that incorporates useful information and features into the list itself. We aim to decrease medication errors across transitions of care, increase awareness of potential drug-drug interactions, improve patient knowledge and self-efficacy regarding medications, decrease polypharmacy, improve prescribing safety and ultimately decrease cost to the health-care system.

  1. A time projection chamber for high accuracy and precision fission cross-section measurements

    NASA Astrophysics Data System (ADS)

    Heffner, M.; Asner, D. M.; Baker, R. G.; Baker, J.; Barrett, S.; Brune, C.; Bundgaard, J.; Burgett, E.; Carter, D.; Cunningham, M.; Deaven, J.; Duke, D. L.; Greife, U.; Grimes, S.; Hager, U.; Hertel, N.; Hill, T.; Isenhower, D.; Jewell, K.; King, J.; Klay, J. L.; Kleinrath, V.; Kornilov, N.; Kudo, R.; Laptev, A. B.; Leonard, M.; Loveland, W.; Massey, T. N.; McGrath, C.; Meharchand, R.; Montoya, L.; Pickle, N.; Qu, H.; Riot, V.; Ruz, J.; Sangiorgio, S.; Seilhan, B.; Sharma, S.; Snyder, L.; Stave, S.; Tatishvili, G.; Thornton, R. T.; Tovesson, F.; Towell, D.; Towell, R. S.; Watson, S.; Wendt, B.; Wood, L.; Yao, L.

    2014-09-01

    The fission Time Projection Chamber (fissionTPC) is a compact (15 cm diameter) two-chamber MICROMEGAS TPC designed to make precision cross-section measurements of neutron-induced fission. The actinide targets are placed on the central cathode and irradiated with a neutron beam that passes axially through the TPC inducing fission in the target. The 4π acceptance for fission fragments and complete charged particle track reconstruction are powerful features of the fissionTPC which will be used to measure fission cross-sections and examine the associated systematic errors. This paper provides a detailed description of the design requirements, the design solutions, and the initial performance of the fissionTPC.

  2. A Time Projection Chamber for High Accuracy and Precision Fission Cross-Section Measurements

    SciTech Connect

    T. Hill; K. Jewell; M. Heffner; D. Carter; M. Cunningham; V. Riot; J. Ruz; S. Sangiorgio; B. Seilhan; L. Snyder; D. M. Asner; S. Stave; G. Tatishvili; L. Wood; R. G. Baker; J. L. Klay; R. Kudo; S. Barrett; J. King; M. Leonard; W. Loveland; L. Yao; C. Brune; S. Grimes; N. Kornilov; T. N. Massey; J. Bundgaard; D. L. Duke; U. Greife; U. Hager; E. Burgett; J. Deaven; V. Kleinrath; C. McGrath; B. Wendt; N. Hertel; D. Isenhower; N. Pickle; H. Qu; S. Sharma; R. T. Thornton; D. Tovwell; R. S. Towell; S.

    2014-09-01

    The fission Time Projection Chamber (fissionTPC) is a compact (15 cm diameter) two-chamber MICROMEGAS TPC designed to make precision cross-section measurements of neutron-induced fission. The actinide targets are placed on the central cathode and irradiated with a neutron beam that passes axially through the TPC inducing fission in the target. The 4p acceptance for fission fragments and complete charged particle track reconstruction are powerful features of the fissionTPC which will be used to measure fission cross-sections and examine the associated systematic errors. This paper provides a detailed description of the design requirements, the design solutions, and the initial performance of the fissionTPC.

  3. Bottom-Up Mechanisms Are Involved in the Relation between Accuracy in Timing Tasks and Intelligence--Further Evidence Using Manipulations of State Motivation

    ERIC Educational Resources Information Center

    Ullen, Fredrik; Soderlund, Therese; Kaaria, Lenita; Madison, Guy

    2012-01-01

    Intelligence correlates with accuracy in various timing tasks. Such correlations could be due to both bottom-up mechanisms, e.g. neural properties that influence both temporal accuracy and cognitive processing, and differences in top-down control. We have investigated the timing-intelligence relation using a simple temporal motor task, isochronous…

  4. Antenna Modeling and Reconstruction Accuracy of Time Domain-Based Image Reconstruction in Microwave Tomography

    PubMed Central

    Padhi, Shantanu K.; Howard, John

    2013-01-01

    Nonlinear microwave imaging heavily relies on an accurate numerical electromagnetic model of the antenna system. The model is used to simulate scattering data that is compared to its measured counterpart in order to reconstruct the image. In this paper an antenna system immersed in water is used to image different canonical objects in order to investigate the implication of modeling errors on the final reconstruction using a time domain-based iterative inverse reconstruction algorithm and three-dimensional FDTD modeling. With the test objects immersed in a background of air and tap water, respectively, we have studied the impact of antenna modeling errors, errors in the modeling of the background media, and made a comparison with a two-dimensional version of the algorithm. In conclusion even small modeling errors in the antennas can significantly alter the reconstructed image. Since the image reconstruction procedure is highly nonlinear general conclusions are very difficult to make. In our case it means that with the antenna system immersed in water and using our present FDTD-based electromagnetic model the imaging results are improved if refraining from modeling the water-wall-air interface and instead just use a homogeneous background of water in the model. PMID:23606825

  5. The Accuracy of Computerized Adaptive Testing in Heterogeneous Populations: A Mixture Item-Response Theory Analysis

    PubMed Central

    Kopec, Jacek A.; Wu, Amery D.; Zumbo, Bruno D.

    2016-01-01

    Background Computerized adaptive testing (CAT) utilizes latent variable measurement model parameters that are typically assumed to be equivalently applicable to all people. Biased latent variable scores may be obtained in samples that are heterogeneous with respect to a specified measurement model. We examined the implications of sample heterogeneity with respect to CAT-predicted patient-reported outcomes (PRO) scores for the measurement of pain. Methods A latent variable mixture modeling (LVMM) analysis was conducted using data collected from a heterogeneous sample of people in British Columbia, Canada, who were administered the 36 pain domain items of the CAT-5D-QOL. The fitted LVMM was then used to produce data for a simulation analysis. We evaluated bias by comparing the referent PRO scores of the LVMM with PRO scores predicted by a “conventional” CAT (ignoring heterogeneity) and a LVMM-based “mixture” CAT (accommodating heterogeneity). Results The LVMM analysis indicated support for three latent classes with class proportions of 0.25, 0.30 and 0.45, which suggests that the sample was heterogeneous. The simulation analyses revealed differences between the referent PRO scores and the PRO scores produced by the “conventional” CAT. The “mixture” CAT produced PRO scores that were nearly equivalent to the referent scores. Conclusion Bias in PRO scores based on latent variable models may result when population heterogeneity is ignored. Improved accuracy could be obtained by using CATs that are parameterized using LVMM. PMID:26930348

  6. Impact of time-variable vegetation on accuracy of rapid hydrologic predictions

    NASA Astrophysics Data System (ADS)

    Stec, Magdalena; Niedzielski, Tomasz

    2016-04-01

    It is crucial to identify the processes that impact errors of hydrologic forecasts. Since existence of vegetation and its ability to store precipitation is an important element of water distribution in the catchment, especially at the beginning of a rainfall event, it may be considered as one of the processes influencing skills of hydrological forecasts. The main objective of the study is to verify the hypothesis that water level predictions are controlled by vegetation dynamics in the contributing mountainous basins. The analysis is conducted for the upper Nysa Klodzka catchment with the outlet in Bardo (SW Poland). The basin includes a mid-mountain abasement covered with crops, while surrounding medium-altitude mountain ranges are mainly covered with forests. We focus on the entire year, from autumn 2013 to summer 2014. Herein, we analyze prediction errors and efficiency measures of hydrologic forecasts provided by two stochastic models - uni- and multivariate autoregressive models as well as their two-model ensemble prediction. In addition, we use the satellite-derived Leaf Area Index (LAI) images from the Moderate Resolution Imaging Spectroradiometer (MODIS). Hydrological prognoses are derived by the HydroProg real-time rapid forecasting system, built at the University of Wroclaw (Poland) in frame of the research project 2011/01/D/ST10/04171 of the National Science Centre of Poland. Correlation analysis between the plant maximum water storage capacity and prediction error/skill statistics (mean absolute error, root mean square error, Nash-Sutcliffe efficiency , index of agreement) is conducted. To cope with small sample size, the bootstrap simulation is performed. We conclude that there is a strong negative association between mean or median prediction errors and vegetation state for all meteorological seasons of a year. This result implies that basins with higher interception potential are more vulnerable to forecast inaccuracy than those with sparse natural

  7. Acousto-optical pulsar processor frequency scale calibration for increase accuracy measurement of time of arrival radioemission impulses

    NASA Astrophysics Data System (ADS)

    Esepkina, Nelli A.; Lavrov, Aleksandr P.; Molodyakov, Sergey A.

    2006-04-01

    The acousto-optical processor (AOP) is based on an acousto-optical spectrum analyzer with a CCD photodetector operating in special pipeline mode (shift-and-add mode), which allows spectral components of the input signal to be added with controlled time delay immediately in the CCD photodetector. The proposed AOP was successfully used on radiotelescope RT-64 (Kalyazin Radio Astronomy Observatory FIAN) for the observation of pulsars at 1 .4 GHz in 45 MHz bandwidth. The AOP frequency scale calibration allows increasing accuracy of measurement of time of arrival radioemission pulses. Experimental results on investigation of AOP work on RT-64 and radioemission pulses profiles for pulsar PSR 1937+21 are submitted.

  8. Accuracy decline of the Brillouin optical time-domain analysis system induced by self-phase modulation

    NASA Astrophysics Data System (ADS)

    Zhou, Yuqing; Chen, Wei; Meng, Zhou

    2016-09-01

    The Brillouin optical time-domain analysis system (BOTDA) is a distributed optical fiber sensing system based on the measurement of the effective Brillouin gain, in which high power pumping pulse is demanded to fulfill optical time domain reflectometry (OTDR) spatial orientation. As for strict rectangular pulse, BGS can maintain Lorentz line profile along the sensor fiber, while the actual rectangular pulse has power transients like the rising edge and failing edge, making BGS broadened or even distorted by the effect of self-phase modulation (SPM), which will induce the decline of the measuring accuracy. A model concerning the effects of pumping pulse power transients on the BGS by means of SPM is established based on the nonlinear Schrodinger equation (NLSE) in regular single mode fiber (SMF).

  9. A reminder on millisecond timing accuracy and potential replication failure in computer-based psychology experiments: An open letter.

    PubMed

    Plant, Richard R

    2016-03-01

    There is an ongoing 'replication crisis' across the field of psychology in which researchers, funders, and members of the public are questioning the results of some scientific studies and the validity of the data they are based upon. However, few have considered that a growing proportion of research in modern psychology is conducted using a computer. Could it simply be that the hardware and software, or experiment generator, being used to run the experiment itself be a cause of millisecond timing error and subsequent replication failure? This article serves as a reminder that millisecond timing accuracy in psychology studies remains an important issue and that care needs to be taken to ensure that studies can be replicated on current computer hardware and software.

  10. Improvement of orbit determination accuracy for Beidou Navigation Satellite System with Two-way Satellite Time Frequency Transfer

    NASA Astrophysics Data System (ADS)

    Tang, Chengpan; Hu, Xiaogong; Zhou, Shanshi; Guo, Rui; He, Feng; Liu, Li; Zhu, Lingfeng; Li, Xiaojie; Wu, Shan; Zhao, Gang; Yu, Yang; Cao, Yueling

    2016-10-01

    The Beidou Navigation Satellite System (BDS) manages to estimate simultaneously the orbits and clock offsets of navigation satellites, using code and carrier phase measurements of a regional network within China. The satellite clock offsets are also directly measured with Two-way Satellite Time Frequency Transfer (TWSTFT). Satellite laser ranging (SLR) residuals and comparisons with the precise ephemeris indicate that the radial error of GEO satellites is much larger than that of IGSO and MEO satellites and that the BDS orbit accuracy is worse than GPS. In order to improve the orbit determination accuracy for BDS, a new orbit determination strategy is proposed, in which the satellite clock measurements from TWSTFT are fixed as known values, and only the orbits of the satellites are solved. However, a constant systematic error at the nanosecond level can be found in the clock measurements, which is obtained and then corrected by differencing the clock measurements and the clock estimates from orbit determination. The effectiveness of the new strategy is verified by a GPS regional network orbit determination experiment. With the IGS final clock products fixed, the orbit determination and prediction accuracy for GPS satellites improve by more than 50% and the 12-h prediction User Range Error (URE) is better than 0.12 m. By processing a 25-day of measurement from the BDS regional network, an optimal strategy for the satellite-clock-fixed orbit determination is identified. User Equivalent Ranging Error is reduced by 27.6% for GEO satellites, but no apparent reduction is found for IGSO/MEO satellites. The SLR residuals exhibit reductions by 59% and 32% for IGSO satellites but no reductions for GEO and MEO satellites.

  11. Analyzing Response Times in Tests with Rank Correlation Approaches

    ERIC Educational Resources Information Center

    Ranger, Jochen; Kuhn, Jorg-Tobias

    2013-01-01

    It is common practice to log-transform response times before analyzing them with standard factor analytical methods. However, sometimes the log-transformation is not capable of linearizing the relation between the response times and the latent traits. Therefore, a more general approach to response time analysis is proposed in the current…

  12. Study of the response time of MR dampers

    NASA Astrophysics Data System (ADS)

    Guan, Xinchun; Guo, Pengfei; Ou, Jinping

    2009-07-01

    Response time is an important parameter which determines the applied fields and practical vibration reduction effects of magnetorheological (MR) dampers. However, up to now, only a few papers discuss the test and analysis of response times. In this paper, the response time of a large-scale MR damper at different velocities and currents was firstly tested. Then, the transient magnetic field excited by the time-variant excitation current was simulated by finite element method (FEM). Based on the variation of the shear yield stress of magnetorheological fluids in the gap between the cylinder and the piston, the response time of the MR damper was investigated. Influences of eddy current and excitation current response time on the damper's response were also explored. Results show that by utilizing finite elements method, the calculated average effective shear yield strength can be used to predict the response time of a MR damper. Electromagnetic response is the predominant factor influencing the response time of a MR damper, and reducing eddy currents is the key to accelerate the response of a MR damper. Moreover, influence of eddy currents is much larger under stepping down excitation currents than stepping up currents, and with a same magnitude of step, no matter when the current increases or decreases, the smaller the initial current, the greater the eddy current affects a damper's response and the longer the response time of damping force is. A fast response excitation current may induce large eddy currents which reduce the response of the damper instead.

  13. Accuracy of real-time single- and multi-beat 3-d speckle tracking echocardiography in vitro.

    PubMed

    Hjertaas, Johannes Just; Fosså, Henrik; Dybdahl, Grete Lunestad; Grüner, Renate; Lunde, Per; Matre, Knut

    2013-06-01

    With little data published on the accuracy of cardiac 3-D strain measurements, we investigated the agreement between 3-D echocardiography and sonomicrometry in an in vitro model with a polyvinyl alcohol phantom. A cardiac scanner with a 3-D probe was used to acquire recordings at 15 different stroke volumes at a heart rate of 60 beats/min, and eight different stroke volumes at a heart rate of 120 beats/min. Sonomicrometry was used as a reference, monitoring longitudinal, circumferential and radial lengths. Both single- and multi-beat acquisitions were recorded. Strain values were compared with sonomicrometer strain using linear correlation coefficients and Bland-Altman analysis. Multi-beat acquisition showed good agreement, whereas real-time images showed less agreement. The best correlation was obtained for a heart rate 60 of beats/min at a volume rate 36.6 volumes/s.

  14. Accuracy of sign interpreting and real-time captioning of science videos for the delivery of instruction to deaf students

    NASA Astrophysics Data System (ADS)

    Sadler, Karen L.

    2009-04-01

    The purpose of this study was to quantitatively examine the impact of third-party support service providers on the quality of science information available to deaf students in regular science classrooms. Three different videotapes that were developed by NASA for high school science classrooms were selected for the study, allowing for different concepts and vocabulary to be examined. The focus was on the accuracy of translation as measured by the number of key science words included in the transcripts (captions) or videos (interpreted). Data were collected via transcripts completed by CART (computer assisted real-time captionists) or through videos of sign language interpreters. All participants were required to listen to and translate these NASA educational videos with no prior experience with this information so as not to influence their delivery. CART personnel using captions were found to be significantly more accurate in the delivery of science words as compared to the sign language interpreters in this study.

  15. A method to improve the stability and accuracy of ANN- and SVM-based time series models for long-term groundwater level predictions

    NASA Astrophysics Data System (ADS)

    Yoon, Heesung; Hyun, Yunjung; Ha, Kyoochul; Lee, Kang-Kun; Kim, Gyoo-Bum

    2016-05-01

    The prediction of long-term groundwater level fluctuations is necessary to effectively manage groundwater resources and to assess the effects of changes in rainfall patterns on groundwater resources. In the present study, a weighted error function approach was utilised to improve the performance of artificial neural network (ANN)- and support vector machine (SVM)-based recursive prediction models for the long-term prediction of groundwater levels in response to rainfall. The developed time series models were applied to groundwater level data from 5 groundwater-monitoring stations in South Korea. The results demonstrated that the weighted error function approach can improve the stability and accuracy of recursive prediction models, especially for ANN models. The comparison of the model performance showed that the recursive prediction performance of the SVM was superior to the performance of the ANN in this case study.

  16. Dispersion of Response Times Reveals Cognitive Dynamics

    ERIC Educational Resources Information Center

    Holden, John G.; Van Orden, Guy C.; Turvey, Michael T.

    2009-01-01

    Trial-to-trial variation in word-pronunciation times exhibits 1/f scaling. One explanation is that human performances are consequent on multiplicative interactions among interdependent processes-interaction dominant dynamics. This article describes simulated distributions of pronunciation times in a further test for multiplicative interactions and…

  17. OSLD energy response performance and dose accuracy at 24 - 1250 keV: Comparison with TLD-100H and TLD-100

    SciTech Connect

    Kadir, A. B. A.; Priharti, W.; Samat, S. B.; Dolah, M. T.

    2013-11-27

    OSLD was evaluated in terms of energy response and accuracy of the measured dose in comparison with TLD-100H and TLD-100. The OSLD showed a better energy response performance for H{sub p}(10) whereas for H{sub p}(0.07), TLD-100H is superior than the others. The OSLD dose accuracy is comparable with the other two dosimeters since it fulfilled the requirement of the ICRP trumpet graph analysis.

  18. Do emergency medical system response times matter for health outcomes?

    PubMed

    Wilde, Elizabeth Ty

    2013-07-01

    The introduction of technology aimed at reducing the response times of emergency medical services has been one of the principal innovations in crisis care over the last several decades. These substantial investments have typically been justified by an assumed link between shorter response times and improved health outcomes. However, current medical research does not generally show a relationship between response time and mortality. In this study, we explain the discrepancy between conventional wisdom and mortality; existing medical research fails to account for the endogeneity of incident severity and response times. Analyzing detailed call-level information from the state of Utah's Bureau of Emergency Medical Services, we measure the impact of response time on mortality and hospital utilization using the distance of the incident from the nearest EMS agency headquarters as an instrument for response time. We find that response times significantly affect mortality and the likelihood of being admitted to the hospital, but not procedures or utilization within the hospital.

  19. Dispersion of Response Times Reveals Cognitive Dynamics

    PubMed Central

    Holden, John G.; Van Orden, Guy C.; Turvey, Michael T.

    2013-01-01

    Trial to trial variation in word pronunciation times exhibits 1/f scaling. One explanation is that human performances are consequent on multiplicative interactions among interdependent processes – interaction dominant dynamics. This article describes simulated distributions of pronunciation times in a further test for multiplicative interactions and interdependence. Individual participant distributions of ≈1100 word pronunciation times are successfully mimicked for each participant in combinations of lognormal and power law behavior. Successful hazard function simulations generalize these results to establish interaction dominant dynamics, in contrast with component dominant dynamics, as a likely mechanism for cognitive activity. PMID:19348544

  20. Using Lunar Observations to Validate Pointing Accuracy and Geolocation, Detector Sensitivity Stability and Static Point Response of the CERES Instruments

    NASA Technical Reports Server (NTRS)

    Daniels, Janet L.; Smith, G. Louis; Priestley, Kory J.; Thomas, Susan

    2014-01-01

    Validation of in-orbit instrument performance is a function of stability in both instrument and calibration source. This paper describes a method using lunar observations scanning near full moon by the Clouds and Earth Radiant Energy System (CERES) instruments. The Moon offers an external source whose signal variance is predictable and non-degrading. From 2006 to present, these in-orbit observations have become standardized and compiled for the Flight Models -1 and -2 aboard the Terra satellite, for Flight Models-3 and -4 aboard the Aqua satellite, and beginning 2012, for Flight Model-5 aboard Suomi-NPP. Instrument performance measurements studied are detector sensitivity stability, pointing accuracy and static detector point response function. This validation method also shows trends per CERES data channel of 0.8% per decade or less for Flight Models 1-4. Using instrument gimbal data and computed lunar position, the pointing error of each detector telescope, the accuracy and consistency of the alignment between the detectors can be determined. The maximum pointing error was 0.2 Deg. in azimuth and 0.17 Deg. in elevation which corresponds to an error in geolocation near nadir of 2.09 km. With the exception of one detector, all instruments were found to have consistent detector alignment from 2006 to present. All alignment error was within 0.1o with most detector telescopes showing a consistent alignment offset of less than 0.02 Deg.

  1. Accuracy and precision of hind limb foot contact timings of horses determined using a pelvis-mounted inertial measurement unit.

    PubMed

    Starke, Sandra D; Witte, Thomas H; May, Stephen A; Pfau, Thilo

    2012-05-11

    Gait analysis using small sensor units is becoming increasingly popular in the clinical context. In order to segment continuous movement from a defined point of the stride cycle, knowledge about footfall timings is essential. We evaluated the accuracy and precision of foot contact timings of a defined limb determined using an inertial sensor mounted on the pelvis of ten horses during walk and trot at different speeds and in different directions. Foot contact was estimated from vertical velocity events occurring before maximum sensor roll towards the contralateral limb. Foot contact timings matched data from a synchronised hoof mounted accelerometer well when velocity minimum was used for walk (mean (SD) difference of 15 (18)ms across horses) and velocity zero-crossing for trot (mean (SD) difference from -4 (14) to 12 (7)ms depending on the condition). The stride segmentation method also remained robust when applied to movement data of hind limb lame horses. In future, this method may find application in segmenting overground sensor data of various species.

  2. Response modalities and time-sharing performance

    NASA Technical Reports Server (NTRS)

    Vidulich, Michael A.

    1986-01-01

    An experiment performed to investigate the role of resource competition and asymmetric transfer in dual-task performance is described. It is shown that there is an advantage to mixed manual/speech response modality configurations that cannot be accounted for by asymmetric transfer. The present results support the multiple resources approach to the application of speech technology. Once speech recognition achieves an acceptable level of operational reliability, speech controls can be used to reduce resource competition and improve performance in multitask environments.

  3. Modeling an Application's Theoretical Minimum and Average Transactional Response Times

    SciTech Connect

    Paiz, Mary Rose

    2015-04-01

    The theoretical minimum transactional response time of an application serves as a ba- sis for the expected response time. The lower threshold for the minimum response time represents the minimum amount of time that the application should take to complete a transaction. Knowing the lower threshold is beneficial in detecting anomalies that are re- sults of unsuccessful transactions. On the converse, when an application's response time falls above an upper threshold, there is likely an anomaly in the application that is causing unusual performance issues in the transaction. This report explains how the non-stationary Generalized Extreme Value distribution is used to estimate the lower threshold of an ap- plication's daily minimum transactional response time. It also explains how the seasonal Autoregressive Integrated Moving Average time series model is used to estimate the upper threshold for an application's average transactional response time.

  4. Accuracy and reliability of multi-GNSS real-time precise positioning: GPS, GLONASS, BeiDou, and Galileo

    NASA Astrophysics Data System (ADS)

    Li, Xingxing; Ge, Maorong; Dai, Xiaolei; Ren, Xiaodong; Fritsche, Mathias; Wickert, Jens; Schuh, Harald

    2015-06-01

    In this contribution, we present a GPS+GLONASS+BeiDou+Galileo four-system model to fully exploit the observations of all these four navigation satellite systems for real-time precise orbit determination, clock estimation and positioning. A rigorous multi-GNSS analysis is performed to achieve the best possible consistency by processing the observations from different GNSS together in one common parameter estimation procedure. Meanwhile, an efficient multi-GNSS real-time precise positioning service system is designed and demonstrated by using the multi-GNSS Experiment, BeiDou Experimental Tracking Network, and International GNSS Service networks including stations all over the world. The statistical analysis of the 6-h predicted orbits show that the radial and cross root mean square (RMS) values are smaller than 10 cm for BeiDou and Galileo, and smaller than 5 cm for both GLONASS and GPS satellites, respectively. The RMS values of the clock differences between real-time and batch-processed solutions for GPS satellites are about 0.10 ns, while the RMS values for BeiDou, Galileo and GLONASS are 0.13, 0.13 and 0.14 ns, respectively. The addition of the BeiDou, Galileo and GLONASS systems to the standard GPS-only processing, reduces the convergence time almost by 70 %, while the positioning accuracy is improved by about 25 %. Some outliers in the GPS-only solutions vanish when multi-GNSS observations are processed simultaneous. The availability and reliability of GPS precise positioning decrease dramatically as the elevation cutoff increases. However, the accuracy of multi-GNSS precise point positioning (PPP) is hardly decreased and few centimeter are still achievable in the horizontal components even with 40 elevation cutoff. At 30 and 40 elevation cutoffs, the availability rates of GPS-only solution drop significantly to only around 70 and 40 %, respectively. However, multi-GNSS PPP can provide precise position estimates continuously (availability rate is more than 99

  5. Effect of storage time and framework design on the accuracy of maxillary cobalt-chromium cast removable partial dentures

    PubMed Central

    Viswambaran, M.; Sundaram, R. K.

    2015-01-01

    Statement of Problem: Inaccuracies in the fit of palatal major connectors may be related to distortion of the wax pattern due to prolonged storage time and faulty major connector design. Purpose: This in vitro study was carried out to find out the effect of storage time and major connector design on the accuracy of cobalt-chromium cast removable partial dentures (RPDs). Materials and Methods: A brass metal die with a Kennedy Class III, modification 1, the partially edentulous arch was used as a master die. Thirty-six refractory casts were fabricated from the master die. The refractory casts were divided into three groups (Group I: Anterior-posterior palatal bar, Group II: Palatal strap and Group III: Palatal plate) based on the design of maxillary major connector and subdivided into four groups (sub Group A: 01 h, sub Group B: 03 h, Sub Group C: 06 h, and sub Group D: 24 h) based on the storage time. For each group, 12 frameworks were fabricated. The influence of wax pattern storage time and the accuracy of the fit palatal major connector designs on the master die were compared. Casting defects (nodules/incompleteness) of the frameworks were also evaluated before finishing and polishing. Repeated measures analysis of variance was used to analyze the data. Results: The gap discrepancy was least in sub Group A (01 h) followed by sub Group B (03 h) and C (06 h) and most in sub Group D (24 h). Statistically significant differences (P < 0.05 in all locations L1–L5) in the fit of the framework were related to the design of the major connector. The gap discrepancy was least in Group I (anterior-posterior palatal bar) followed by Group II (palatal strap) and most in Group II (palatal plate). Conclusions: It is recommended that the wax patterns for RPD to be invested immediately on completion of the wax procedure. The selection of a major connector design is crucial for an accurate fit of RPD. PMID:26681850

  6. Accuracy of a Real-Time, Computerized, Binocular, Three-Dimensional Trajectory-Tracking Device for Recording Functional Mandibular Movements

    PubMed Central

    Zhao, Tian; Yang, Huifang; Sui, Huaxin; Salvi, Satyajeet Sudhir; Wang, Yong; Sun, Yuchun

    2016-01-01

    Objective Developments in digital technology have permitted researchers to study mandibular movements. Here, the accuracy of a real-time, computerized, binocular, three-dimensional (3D) trajectory-tracking device for recording functional mandibular movements was evaluated. Methods An occlusal splint without the occlusal region was created based on a plaster cast of the lower dentition. The splint was rigidly connected with a target on its labial side and seated on the cast. The cast was then rigidly attached to the stage of a high-precision triaxial electronic translator, which was used to move the target-cast-stage complex. Half-circular movements (5.00-mm radius) in three planes (XOY, XOZ, YOZ) and linear movements along the x-axis were performed at 5.00 mm/s. All trajectory points were recorded with the binocular 3D trajectory-tracking device and fitted to arcs or lines, respectively, with the Imageware software. To analyze the accuracy of the trajectory-tracking device, the mean distances between the trajectory points and the fitted arcs or lines were measured, and the mean differences between the lengths of the fitted arcs’ radii and a set value (5.00 mm) were then calculated. A one-way analysis of variance was used to evaluate the spatial consistency of the recording accuracy in three different planes. Results The mean distances between the trajectory points and fitted arcs or lines were 0.076 ± 0.033 mm or 0.089 ± 0.014 mm. The mean difference between the lengths of the fitted arcs’ radii and the set value (5.00 mm) was 0.025 ± 0.071 mm. A one-way ANOVA showed that the recording errors in three different planes were not statistically significant. Conclusion These results suggest that the device can record certain movements at 5.00 mm/s, which is similar to the speed of functional mandibular movements. In addition, the recordings had an error of <0.1 mm and good spatial consistency. Thus, the device meets some of the requirements necessary for

  7. A Study of Bayesian Estimation and Comparison of Response Time Models in Item Response Theory

    ERIC Educational Resources Information Center

    Suh, Hongwook

    2010-01-01

    Response time has been regarded as an important source for investigating the relationship between human performance and response speed. It is important to examine the relationship between response time and item characteristics, especially in the perspective of the relationship between response time and various factors that affect examinee's…

  8. Accuracy of sea level predictions with lead time of one week: a comparison between Prognocean and MyOcean

    NASA Astrophysics Data System (ADS)

    Swierczynska, Malgorzata; Mizinski, Bartlomiej; Niedzielski, Tomasz

    2015-04-01

    There exist several systems which produce sea level forecasts in real time, with lead times ranging from hours to two weeks in the future. One of the recently developed solutions is Prognocean, the system that has been built and implemented at the University of Wroclaw, Poland. Its main feature is that it uses simple time series models to predict sea level anomaly maps, and does it for lead times ranging from 1 to 14 days with daily update. The empirical data-based models are fitted in real time both to individual grids (polynomial-harmonic model, polynomial-harmonic model combined with autoregressive model, polynomial-harmonic model combined with threshold autoregressive model) and to numerous grids forming a spatial latitude x longitude window of 3˚ x 5˚ (polynomial-harmonic model combined with multivariate autoregressive model). Although their simplicity, the approaches have already been shown to produce sea level anomaly predictions of reasonable accuracy. However, none of the analyses targeted at the comparative study which would present the skills of the Prognocean system against a background of the performance of other systems that use physically-based models. This study aims to fill this gap by comparing Prognocean-based predictions for one week into the future with the corresponding prognoses calculated by MyOcean. The reader is provided with the objectively-calculated set of statistics, presented as maps, which describes prediction errors (mean absolute error, root mean square error, index of agreement) and prediction skills (prediction efficiency, coefficient of determination) of the two systems. The exercise enables to compare the skills of the approaches, and the gridwise comparison allows one to identify areas of superior performance of each system.

  9. Efficiency and accuracy of the perturbation response coefficient generation method for whole core comet calculations in BWR and CANDU configurations

    SciTech Connect

    Zhang, D.; Rahnema, F.

    2013-07-01

    The coarse mesh transport method (COMET) is a highly accurate and efficient computational tool which predicts whole-core neutronics behaviors for heterogeneous reactor cores via a pre-computed eigenvalue-dependent response coefficient (function) library. Recently, a high order perturbation method was developed to significantly improve the efficiency of the library generation method. In that work, the method's accuracy and efficiency was tested in a small PWR benchmark problem. This paper extends the application of the perturbation method to include problems typical of the other water reactor cores such as BWR and CANDU bundles. It is found that the response coefficients predicted by the perturbation method for typical BWR bundles agree very well with those directly computed by the Monte Carlo method. The average and maximum relative errors in the surface-to-surface response coefficients are 0.02%-0.05% and 0.06%-0.25%, respectively. For CANDU bundles, the corresponding quantities are 0.01%-0.05% and 0.04% -0.15%. It is concluded that the perturbation method is highly accurate and efficient with a wide range of applicability. (authors)

  10. Accuracy of travel time distribution (TTD) models as affected by TTD complexity, observation errors, and model and tracer selection

    USGS Publications Warehouse

    Green, Christopher T.; Zhang, Yong; Jurgens, Bryant C.; Starn, J. Jeffrey; Landon, Matthew K.

    2014-01-01

    Analytical models of the travel time distribution (TTD) from a source area to a sample location are often used to estimate groundwater ages and solute concentration trends. The accuracies of these models are not well known for geologically complex aquifers. In this study, synthetic datasets were used to quantify the accuracy of four analytical TTD models as affected by TTD complexity, observation errors, model selection, and tracer selection. Synthetic TTDs and tracer data were generated from existing numerical models with complex hydrofacies distributions for one public-supply well and 14 monitoring wells in the Central Valley, California. Analytical TTD models were calibrated to synthetic tracer data, and prediction errors were determined for estimates of TTDs and conservative tracer (NO3−) concentrations. Analytical models included a new, scale-dependent dispersivity model (SDM) for two-dimensional transport from the watertable to a well, and three other established analytical models. The relative influence of the error sources (TTD complexity, observation error, model selection, and tracer selection) depended on the type of prediction. Geological complexity gave rise to complex TTDs in monitoring wells that strongly affected errors of the estimated TTDs. However, prediction errors for NO3− and median age depended more on tracer concentration errors. The SDM tended to give the most accurate estimates of the vertical velocity and other predictions, although TTD model selection had minor effects overall. Adding tracers improved predictions if the new tracers had different input histories. Studies using TTD models should focus on the factors that most strongly affect the desired predictions.

  11. A Lognormal Model for Response Times on Test Items

    ERIC Educational Resources Information Center

    van der Linden, Wim J.

    2006-01-01

    A lognormal model for the response times of a person on a set of test items is investigated. The model has a parameter structure analogous to the two-parameter logistic response models in item response theory, with a parameter for the speed of each person as well as parameters for the time intensity and discriminating power of each item. It is…

  12. Effect of Storage Time of Extended-Pour and Conventional Alginate Impressions on Dimensional Accuracy of Casts

    PubMed Central

    Rohanian, Ahmad; Ommati Shabestari, Ghasem; Zeighami, Somayeh; Samadi, Mohammad Javad; Shamshiri, Ahmad Reza

    2014-01-01

    Objectives: Some manufacturers claim to have produced new irreversible hydro-colloids that are able to maintain their dimensional stability during storage. The present study evaluated the effect of storage time on dimensional stability of three alginates: Hydrogum 5, Tropicalgin and Alginoplast. Materials and Methods: In this experimental in-vitro trial, a total of 90 alginate impressions were made from a Dentoform model using Hydrogum 5, Tropicalgin and Alginoplast alginates. The impressions were stored in a sealed plastic bag without a damp paper towel for 0, 24, 48, 72 and 120 hours and then poured with type III dental stone. Cross-arch (facial of 6 to facial of 6 on the opposite side) and antero-posterior (distal of right first molar to the ipsilateral central incisor) measurements were made with a digital caliper on the casts. Data were analyzed by two-way and one-way ANOVA and Tukey’s post-hoc test (P<0.05). Results: Alginate type and the pouring time significantly affected the dimensional stability of alginate impressions (both Ps<0.001). Pouring of Hydrogum 5 impressions can be delayed for up to 120 hours without significant dimensional changes. Alginoplast impressions may be poured after 72 hours, but Tropicalgin should be poured immediately and the storage time should not be more than 24 hours. Conclusion: Immediate pouring of alginate impressions provides the highest accuracy in reproducing the teeth and adjacent tissues; however, this study demonstrated that pouring may be delayed for up to five days using extended-pour (Hydrogum 5) alginates. PMID:25628695

  13. Time-dependent onshore tsunami response

    USGS Publications Warehouse

    Apotsos, Alex; Gelfenbaum, Guy R.; Jaffe, Bruce E.

    2012-01-01

    While bulk measures of the onshore impact of a tsunami, including the maximum run-up elevation and inundation distance, are important for hazard planning, the temporal evolution of the onshore flow dynamics likely controls the extent of the onshore destruction and the erosion and deposition of sediment that occurs. However, the time-varying dynamics of actual tsunamis are even more difficult to measure in situ than the bulk parameters. Here, a numerical model based on the non-linear shallow water equations is used to examine the effects variations in the wave characteristics, bed slope, and bottom roughness have on the temporal evolution of the onshore flow. Model results indicate that the onshore flow dynamics vary significantly over the parameter space examined. For example, the flow dynamics over steep, smooth morphologies tend to be temporally symmetric, with similar magnitude velocities generated during the run-up and run-down phases of inundation. Conversely, on shallow, rough onshore topographies the flow dynamics tend to be temporally skewed toward the run-down phase of inundation, with the magnitude of the flow velocities during run-up and run-down being significantly different. Furthermore, for near-breaking tsunami waves inundating over steep topography, the flow velocity tends to accelerate almost instantaneously to a maximum and then decrease monotonically. Conversely, when very long waves inundate over shallow topography, the flow accelerates more slowly and can remain steady for a period of time before beginning to decelerate. These results indicate that a single set of assumptions concerning the onshore flow dynamics cannot be applied to all tsunamis, and site specific analyses may be required.

  14. Fast Time Response Electromagnetic Disruption Mitigation Concept

    DOE PAGES

    Raman, R.; Jarboe, T.; Jernigan, Thomas C.; ...

    2015-09-28

    An important and urgent issue for ITER is predicting and controlling disruptions. Tokamaks and spherical tokamaks have the potential to disrupt. Methods to rapidly quench the discharge after an impending disruption is detected are essential to protect the vessel and internal components. The warning time for the onset of some disruptions in tokamaks could be <10 ms, which poses stringent requirements on the disruption mitigation system for reactor systems. In this proposed method, a cylindrical boron nitride projectile containing a radiative payload composed of boron, boron nitride, or beryllium particulate matter and weighing similar to 15 g is accelerated tomore » velocities on the order of 1 to 2 km/s in <2 ms in a linear rail gun accelerator. A partially fragmented capsule is then injected into the tokamak discharge in the 3- to 6-ms timescale, where the radiative payload is dispersed. The device referred to as an electromagnetic particle injector has the potential to meet the short warning timescales for which a reactor disruption mitigation system must be built. The system is fully electromagnetic, with no mechanical moving parts, which ensures high reliability after a period of long standby.« less

  15. Fast Time Response Electromagnetic Disruption Mitigation Concept

    SciTech Connect

    Raman, R.; Jarboe, T.; Jernigan, Thomas C.; Menard, J.; Gerhardt, S. P.; Ono, M.; Baylor, Larry R.; Lay, W. S.

    2015-09-28

    An important and urgent issue for ITER is predicting and controlling disruptions. Tokamaks and spherical tokamaks have the potential to disrupt. Methods to rapidly quench the discharge after an impending disruption is detected are essential to protect the vessel and internal components. The warning time for the onset of some disruptions in tokamaks could be <10 ms, which poses stringent requirements on the disruption mitigation system for reactor systems. In this proposed method, a cylindrical boron nitride projectile containing a radiative payload composed of boron, boron nitride, or beryllium particulate matter and weighing similar to 15 g is accelerated to velocities on the order of 1 to 2 km/s in <2 ms in a linear rail gun accelerator. A partially fragmented capsule is then injected into the tokamak discharge in the 3- to 6-ms timescale, where the radiative payload is dispersed. The device referred to as an electromagnetic particle injector has the potential to meet the short warning timescales for which a reactor disruption mitigation system must be built. The system is fully electromagnetic, with no mechanical moving parts, which ensures high reliability after a period of long standby.

  16. Accuracy of PARTwear Inertial Sensor and Optojump Optical Measurement System for Measuring Ground Contact Time During Running.

    PubMed

    Ammann, Rahel; Taube, Wolfgang; Wyss, Thomas

    2016-07-01

    Ammann, R, Taube, W, and Wyss, T. Accuracy of PARTwear inertial sensor and Optojump optical measurement system for measuring ground contact time during running. J Strength Cond Res 30(7): 2057-2063, 2016-The aim of this study was to validate the detection of ground contact time (GCT) during running in 2 differently working systems: a small inertial measurement sensor, PARTwear (PW), worn on the shoe laces, and the optical measurement system, Optojump (OJ), placed on the track. Twelve well-trained subjects performed 12 runs each on an indoor track at speeds ranging from 3.0 to 9.0 m·s. GCT of one step per run (total 144) was simultaneously obtained by the PW, the OJ, and a high-speed video camera (HSC), whereby the latter served as reference system. The sampling rate was 1,000 Hz for all methods. Compared with the HSC, the PW and the OJ systems underestimated GCT by -1.3 ± 6.1% and -16.5 ± 6.7% (p-values ≤ 0.05), respectively. The intraclass correlation coefficients between PW and HSC and between OJ and HSC were 0.984 and 0.853 (p-values < 0.001), respectively. Despite the constant systematic underestimation of GCT, analyses indicated that PW successfully recorded GCT over a wide range of speeds. However, results showed only moderate validity for the OJ system, with increasing errors when speed decreased. In conclusion, the PW proved to be a highly useful and valid application, and its use can be recommended not only for laboratory settings but also for field applications. In contrast, data on GCT obtained by OJ during running must be treated with caution, specifically when running speed changes or when comparisons are made with GCT data collected by other measurement systems.

  17. Increasing the accuracy and temporal resolution of two-filter radon-222 measurements by correcting for the instrument response

    NASA Astrophysics Data System (ADS)

    Griffiths, Alan D.; Chambers, Scott D.; Williams, Alastair G.; Werczynski, Sylvester

    2016-06-01

    Dual-flow-loop two-filter radon detectors have a slow time response, which can affect the interpretation of their output when making continuous observations of near-surface atmospheric radon concentrations. While concentrations are routinely reported hourly, a calibrated model of detector performance shows that ˜ 40 % of the signal arrives more than an hour after a radon pulse is delivered. After investigating several possible ways to correct for the detector's slow time response, we show that a Bayesian approach using a Markov chain Monte Carlo sampler is an effective method. After deconvolution, the detector's output is redistributed into the appropriate counting interval and a 10 min temporal resolution can be achieved under test conditions when the radon concentration is controlled. In the case of existing archived observations, collected under less ideal conditions, the data can be retrospectively reprocessed at 30 min resolution. In one case study, we demonstrate that a deconvolved radon time series was consistent with the following: measurements from a fast-response carbon dioxide monitor; grab samples from an aircraft; and a simple mixing height model. In another case study, during a period of stable nights and days with well-developed convective boundary layers, a bias of 18 % in the mean daily minimum radon concentration was eliminated by correcting for the instrument response.

  18. 40 CFR 1066.245 - Response time verification.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 33 2014-07-01 2014-07-01 false Response time verification. 1066.245 Section 1066.245 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS VEHICLE-TESTING PROCEDURES Dynamometer Specifications § 1066.245 Response time verification....

  19. 40 CFR 1066.245 - Response time verification.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 34 2012-07-01 2012-07-01 false Response time verification. 1066.245 Section 1066.245 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS VEHICLE-TESTING PROCEDURES Dynamometer Specifications § 1066.245 Response time verification....

  20. Hierarchical Diffusion Models for Two-Choice Response Times

    ERIC Educational Resources Information Center

    Vandekerckhove, Joachim; Tuerlinckx, Francis; Lee, Michael D.

    2011-01-01

    Two-choice response times are a common type of data, and much research has been devoted to the development of process models for such data. However, the practical application of these models is notoriously complicated, and flexible methods are largely nonexistent. We combine a popular model for choice response times--the Wiener diffusion…

  1. Testing for Aberrant Behavior in Response Time Modeling

    ERIC Educational Resources Information Center

    Marianti, Sukaesi; Fox, Jean-Paul; Avetisyan, Marianna; Veldkamp, Bernard P.; Tijmstra, Jesper

    2014-01-01

    Many standardized tests are now administered via computer rather than paper-and-pencil format. In a computer-based testing environment, it is possible to record not only the test taker's response to each question (item) but also the amount of time spent by the test taker in considering and answering each item. Response times (RTs) provide…

  2. 10 CFR 1303.107 - Timing of responses to requests.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 4 2010-01-01 2010-01-01 false Timing of responses to requests. 1303.107 Section 1303.107 Energy NUCLEAR WASTE TECHNICAL REVIEW BOARD PUBLIC INFORMATION AND REQUESTS § 1303.107 Timing of responses to requests. (a) General. The Board shall normally respond to requests in the order of...

  3. 10 CFR 1303.107 - Timing of responses to requests.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 4 2014-01-01 2014-01-01 false Timing of responses to requests. 1303.107 Section 1303.107 Energy NUCLEAR WASTE TECHNICAL REVIEW BOARD PUBLIC INFORMATION AND REQUESTS § 1303.107 Timing of responses to requests. (a) General. The Board shall normally respond to requests in the order of...

  4. Linking Response-Time Parameters onto a Common Scale

    ERIC Educational Resources Information Center

    van der Linden, Wim J.

    2010-01-01

    Although response times on test items are recorded on a natural scale, the scale for some of the parameters in the lognormal response-time model (van der Linden, 2006) is not fixed. As a result, when the model is used to periodically calibrate new items in a testing program, the parameter are not automatically mapped onto a common scale. Several…

  5. Ejection time-corrected systolic velocity improves accuracy in the evaluation of myocardial dysfunction: a study in piglets.

    PubMed

    Odland, Hans Henrik; Kro, Grete Anette Birkeland; Munkeby, Berit H; Edvardsen, Thor; Saugstad, Ola Didrik; Thaulow, Erik

    2010-10-01

    This study aimed to assess the effect of correcting for the impact of heart rate (HR) or ejection time (ET) on myocardial velocities in the long axis in piglets undergoing hypoxia. The ability to eject a higher volume at a fixed ET is a characteristic of contractility in the heart. Systolic velocity of the atrioventricular annulus displacement is directly related to volume changes of the ventricle. Both ET and systolic velocity may be measured in a single heartbeat. In 29 neonatal pigs, systolic velocity and ET were measured with tissue Doppler techniques in the mitral valve annulus, the tricuspid valve annulus, and the septum. All ejection time corrected velocities (S((ET)), mean ± SEM, cm/s) decreased significantly during hypoxia (S(mva(ET)) 15.5 ± 0.2 to 13.2 ± 0.3 (p < 0.001), S(septal(ET)) 9.9 ± 0.1 to 7.8 ± 0.2 (p < 0.001), S(tva(ET)) 12.1 ± 0.2 to 9.8 ± 0.3 (p < 0.001)). The magnitude of change from baseline to hypoxia was greater for ejection time corrected systolic velocities than for RR-interval corrected velocities (mean ± SEM, cm/s); ΔS(mva(ET)) 2.3 ± 2.0 vs. ΔS(mva(RR)) 1.6 ± 1.1 (p = 0.02), ΔS(septal(ET)) 2.1 ± 1.0 vs. ΔS(septal(RR)) 1.6 ± 1.0 (p < 0.01), ΔS(tva(ET)) 2.3 ± 1.1 vs. ΔS(tva(RR)) 1.8 ± 1.3 (p = 0.04). The receiver operator characteristic (ROC) showed superior performance of S((ET)) compared with uncorrected velocities. The decrease in S((ET)) during hypoxia was not influenced by important hemodynamic determinants. ET-corrected systolic velocity improves accuracy and decreases variability in the evaluation of systolic longitudinal function and contractility during global hypoxia in neonatal pigs compared with systolic velocity alone. It is robust toward hemodynamic changes. This novel method has the potential of becoming a useful tool in clinical practice.

  6. Passenger comfort response times as a function of aircraft motion

    NASA Technical Reports Server (NTRS)

    Rinalducci, E. J.

    1975-01-01

    The relationship between a passenger's response time of changes in level of comfort experienced as a function of aircraft motion was examined. The aircraft used in this investigation was capable of providing a wide range of vertical and transverse accelerations by means of direct lift flap control surfaces and side force generator surfaces in addition to normal control surfaces. Response times to changes in comfort were recorded along with the passenger's rating of comfort on a five point scale. In addition, a number of aircraft motion variables including vertical and transverse accelerations were also recorded. Results indicate some relationship between human comfort response times to reaction time data.

  7. Computer Response Time Measurements of Mood, Fatigue and Symptom Scale Items: Implications for Scale Response Time Uses.

    ERIC Educational Resources Information Center

    Ryman, David H.; And Others

    1988-01-01

    Describes study conducted with U.S. Marine Corps enlisted personnel to measure response time to computer-administered questionnaire items, and to evaluate how measurement of response time might be useful in various research areas. Topics addressed include mood states; the occurrence of straight lining; and experimental effects of sleep loss and…

  8. Improving Item Response Theory Model Calibration by Considering Response Times in Psychological Tests

    ERIC Educational Resources Information Center

    Ranger, Jochen; Kuhn, Jorg-Tobias

    2012-01-01

    Research findings indicate that response times in personality scales are related to the trait level according to the so-called speed-distance hypothesis. Against this background, Ferrando and Lorenzo-Seva proposed a latent trait model for the responses and response times in a test. The model consists of two components, a standard item response…

  9. An Item Response Theory Model for Incorporating Response Time Data in Binary Personality Items

    ERIC Educational Resources Information Center

    Ferrando, Pere J.; Lorenzo-Seva, Urbano

    2007-01-01

    This article describes a general item response theory model for personality items that allows the information provided by the item response times to be used to estimate the individual trait levels. The submodel describing the item response times is a modification of Thissen's log-linear model and is based on the distance-difficulty hypothesis in…

  10. Neural Basis of Adaptive Response Time Adjustment during Saccade Countermanding

    PubMed Central

    Pouget, Pierre; Logan, Gordon D.; Palmeri, Thomas J.; Boucher, Leanne; Paré, Martin; Schall, Jeffrey D.

    2011-01-01

    Humans and macaque monkeys adjust their response time adaptively in stop signal (countermanding) tasks, responding slower after stop-signal trials than after control trials with no stop signal. We investigated the neural mechanism underlying this adaptive response time adjustment in macaque monkeys performing a saccade countermanding task. Earlier research showed that movements are initiated when the random accumulation of presaccadic movement-related activity reaches a fixed threshold. We found that a systematic delay in response time after stop signal trials was accomplished not through a change of threshold, baseline, or accumulation rate, but instead through a change in the time when activity first began to accumulate. The neurons underlying movement initiation have been identified with mathematical accumulator models of response time performance. Therefore, this new result provides surprising new insights into the neural instantiation of stochastic accumulator models and the mechanisms through which executive control can be exerted. PMID:21880921

  11. Thermal emittance and response time of a cesium antimonide photocathode

    NASA Astrophysics Data System (ADS)

    Cultrera, Luca; Bazarov, Ivan; Bartnik, Adam; Dunham, Bruce; Karkare, Siddharth; Merluzzi, Richard; Nichols, Matthew

    2011-10-01

    Measurements of the intrinsic emittance and response time of a Cs3Sb photocathode are presented. The emittance is obtained with a solenoid scan technique using a high voltage dc photoemission gun. Photoemission response time is evaluated using a RF deflecting cavity synchronized to a picosecond laser pulse train. We find that Cs3Sb has both small mean transverse energy, 160 ± 10 meV at 532 nm laser wavelength, and a prompt response time (below the resolution of our measurement) making it a suitable material for high brightness electron photoinjectors.

  12. Diminished Response of Arctic Plants to Warming over Time

    PubMed Central

    Kremers, Kelseyann S.; Hollister, Robert D.; Oberbauer, Steven F.

    2015-01-01

    The goal of this study is to determine if the response of arctic plants to warming is consistent across species, locations and time. This study examined the impact of experimental warming and natural temperature variation on plants at Barrow and Atqasuk, Alaska beginning in 1994. We considered observations of plant performance collected from 1994–2000 “short-term” and those from 2007–2012 “long-term”. The plant traits reported are the number of inflorescences, inflorescence height, leaf length, and day of flower emergence. These traits can inform us about larger scale processes such as plant reproductive effort, plant growth, and plant phenology, and therefore provide valuable insight into community dynamics, carbon uptake, and trophic interactions. We categorized traits of all species monitored at each site into temperature response types. We then compared response types across traits, plant growth forms, sites, and over time to analyze the consistency of plant response to warming. Graminoids were the most responsive to warming and showed a positive response to temperature, while shrubs were generally the least responsive. Almost half (49%) of response types (across all traits, species, and sites combined) changed from short-term to long-term. The percent of plants responsive to warming decreased from 57% (short-term) to 46% (long-term). These results indicate that the response of plants to warming varies over time and has diminished overall in recent years. PMID:25767881

  13. Response timing and muscular coordination in fencing: a comparison of elite and novice fencers.

    PubMed

    Williams, L R; Walmsley, A

    2000-12-01

    Reaction time (RT), movement time (MT), total response time (RMT) and accuracy of elite and novice fencers was studied under three levels of target choice (single-, two- and four-targets) with three variations of movement distance (short, medium and long lunge). In addition, electromyographic activity (EMG) of selected upper and lower limb muscles was used to compare the two groups. The elite subjects were faster for RT and RMT and displayed a higher level of accuracy. The hypothesis that increasing choice would cause increases in RT was not upheld. Except for some differentiation between the short and the two longer distances, the effects of movement distance were not marked. Qualitative and quantitative analysis of EMG revealed the high consistency of response patterns within subjects and highlighted the synergistic roles of selected muscles in distinguishing between elite and novice fencers. These findings confirm that differences in the technical skill of fencers can be distinguished in the laboratory through a combination of response timing measures in association with measures of muscle action. They also draw attention to practical implications for individual skill assessment and training. Analysis of pre-movement muscle activity provided moderate support for the hypothesis that it was part of a single control process and indicates that a dual process can involve both the maintenance of postural stability and the generation of movement. It is suggested that different movement contexts can lead to different levels of coordination between the system controlling posture and that controlling movement.

  14. The Episodic Engram Transformed: Time Reduces Retrieval-Related Brain Activity but Correlates It with Memory Accuracy

    ERIC Educational Resources Information Center

    Furman, Orit; Mendelsohn, Avi; Dudai, Yadin

    2012-01-01

    We took snapshots of human brain activity with fMRI during retrieval of realistic episodic memory over several months. Three groups of participants were scanned during a memory test either hours, weeks, or months after viewing a documentary movie. High recognition accuracy after hours decreased after weeks and remained at similar levels after…

  15. Head and Neck PET/CT: Therapy Response Interpretation Criteria (Hopkins Criteria)—Interreader Reliability, Accuracy, and Survival Outcomes

    PubMed Central

    Marcus, Charles; Ciarallo, Anthony; Tahari, Abdel K.; Mena, Esther; Koch, Wayne; Wahl, Richard L.; Kiess, Ana P.; Kang, Hyunseok; Subramaniam, Rathan M.

    2015-01-01

    There has been no established qualitative system of interpretation for therapy response assessment using PET/CT for head and neck cancers. The objective of this study was to validate the Hopkins interpretation system to assess therapy response and survival outcome in head and neck squamous cell cancer patients (HNSCC). Methods The study included 214 biopsy-proven HNSCC patients who underwent a posttherapy PET/CT study, between 5 and 24 wk after completion of treatment. The median follow-up was 27 mo. PET/CT studies were interpreted by 3 nuclear medicine physicians, independently. The studies were scored using a qualitative 5-point scale, for the primary tumor, for the right and left neck, and for overall assessment. Scores 1, 2, and 3 were considered negative for tumors, and scores 4 and 5 were considered positive for tumors. The Cohen κ coefficient (κ) was calculated to measure interreader agreement. Overall survival (OS) and progression-free survival (PFS) were analyzed by Kaplan–Meier plots with a Mantel–Cox log-rank test and Gehan Breslow Wilcoxon test for comparisons. Results Of the 214 patients, 175 were men and 39 were women. There was 85.98%, 95.33%, 93.46%, and 87.38% agreement between the readers for overall, left neck, right neck, and primary tumor site response scores, respectively. The corresponding κ coefficients for interreader agreement between readers were, 0.69–0.79, 0.68–0.83, 0.69–0.87, and 0.79–0.86 for overall, left neck, right neck, and primary tumor site response, respectively. The sensitivity, specificity, positive predictive value, negative predictive value, and overall accuracy of the therapy assessment were 68.1%, 92.2%, 71.1%, 91.1%, and 86.9%, respectively. Cox multivariate regression analysis showed human papillomavirus (HPV) status and PET/CT interpretation were the only factors associated with PFS and OS. Among the HPV-positive patients (n = 123), there was a significant difference in PFS (hazard ratio [HR], 0.14; 95

  16. 45 CFR 1171.7 - Timing of responses to requests.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... FREEDOM OF INFORMATION ACT § 1171.7 Timing of responses to requests. (a) In general. The NEH customarily... requester must submit a statement, certified to be true and correct to the requester's best knowledge...

  17. 18 CFR 1301.5 - Timing of responses to requests.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... PROCEDURES Freedom of Information Act § 1301.5 Timing of responses to requests. (a) In general, TVA... seeks expedited processing must submit a statement, certified to be true and correct to the best of...

  18. 22 CFR 706.30 - Timing of responses to requests.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... DISCLOSURE UNDER THE FREEDOM OF INFORMATION ACT Processing of Requests § 706.30 Timing of responses to... expedited processing must submit a statement, certified to be true and correct, explaining in detail...

  19. 36 CFR 1600.4 - Timing of responses to requests.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Procedures for Disclosure of Records Under the Freedom of Information Act § 1600.4 Timing of responses to... true and correct to the best of your knowledge and belief, explaining in detail the basis...

  20. 36 CFR 1600.4 - Timing of responses to requests.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Procedures for Disclosure of Records Under the Freedom of Information Act § 1600.4 Timing of responses to... true and correct to the best of your knowledge and belief, explaining in detail the basis...

  1. Information Transfer by Reader Service Cards. A Response Time Analysis

    ERIC Educational Resources Information Center

    Bottle, Robert R.; Emery, Betty L.

    1971-01-01

    Some 80 percent of controlled circulation journals provide Reader Service Cards. The responses obtained with those from a sample of ten journals is reported and the data are analyzed in terms of yield, postal and other delays. Response times approximated a normal distribution with an overall mean of 5.8 weeks. (2 references) (Author/NH)

  2. A Mixture Rasch Model with Item Response Time Components

    ERIC Educational Resources Information Center

    Meyer, J. Patrick

    2010-01-01

    An examinee faced with a test item will engage in solution behavior or rapid-guessing behavior. These qualitatively different test-taking behaviors bias parameter estimates for item response models that do not control for such behavior. A mixture Rasch model with item response time components was proposed and evaluated through application to real…

  3. Grade of Membership Response Time Model for Detecting Guessing Behaviors

    ERIC Educational Resources Information Center

    Pokropek, Artur

    2016-01-01

    A response model that is able to detect guessing behaviors and produce unbiased estimates in low-stake conditions using timing information is proposed. The model is a special case of the grade of membership model in which responses are modeled as partial members of a class that is affected by motivation and a class that responds only according to…

  4. Response time to colored stimuli in the full visual field

    NASA Technical Reports Server (NTRS)

    Haines, R. F.; Dawson, L. M.; Galvan, T.; Reid, L. M.

    1975-01-01

    Peripheral visual response time was measured in seven dark adapted subjects to the onset of small (45' arc diam), brief (50 msec), colored (blue, yellow, green, red) and white stimuli imaged at 72 locations within their binocular field of view. The blue, yellow, and green stimuli were matched for brightness at about 2.6 sub log 10 units above their absolute light threshold, and they appeared at an unexpected time and location. These data were obtained to provide response time and no-response data for use in various design disciplines involving instrument panel layout. The results indicated that the retina possesses relatively concentric regions within each of which mean response time can be expected to be of approximately the same duration. These regions are centered near the fovea and extend farther horizontally than vertically. Mean foveal response time was fastest for yellow and slowest for blue. Three and one-half percent of the total 56,410 trials presented resulted in no-responses. Regardless of stimulus color, the lowest percentage of no-responses occurred within 30 deg arc from the fovea and the highest within 40 deg to 80 deg arc below the fovea.

  5. Investigations on response time of magnetorheological elastomer isolator for real-time control implementation

    NASA Astrophysics Data System (ADS)

    Gu, Xiaoyu; Li, Yancheng; Li, Jianchun

    2016-11-01

    Utilising the unique features of MRE materials for vibration isolators has been intensively studied over the last several years. Real-time control of the MRE isolators holds the key to unlock MRE materials’ unique characteristics, i.e. instantly changeable shear modulus in continuous and reverse fashion. However, one of the critical issues for the applications of real-time control is the response time delay of MRE vibration isolators, which has not yet been fully addressed and studied. This paper identified the inherent response time of the MRE isolator and explored two feasible approaches to minimise the response time delay. Experiments were designed and conducted to evaluate the effectiveness of the proposed approaches on minimising time delay on: (i) the transient response of current of a large coil that generates magnetic field and (ii) the transient response of shear force from the MRE isolator. The results show that the proposed approaches are effective and promising. For example, the proposed approach is able to reduce the force response time from 421 ms to 52 ms at rising and from 400 ms to 48 ms falling edges respectively. Such level of short response time of the MRE isolators demonstrates the feasibility of application of real-time control and hence is the essential step on the realisation of real-time control of vibration suppression system based on MRE isolator.

  6. Effects of Prolonged Work on Data Entry Speed and Accuracy

    ERIC Educational Resources Information Center

    Healy,Alice F.; Kole,James A.; Buck-Gengle,Carolyn J.; Bourne,Lyle E.

    2004-01-01

    In 2 experiments, participants used a keyboard to enter 4-digit numbers presented on a computer monitor under conditions promoting fatigue. In Experiment 1, accuracy of data entry declined but response times improved over time, reflecting an increasing speed-accuracy trade-off. In Experiment 2, the (largely cognitive) time to enter the initial…

  7. Improved time response for large area microchannel plate photomultiplier tubes in fusion diagnostics

    SciTech Connect

    Milnes, J. S. Conneely, T. M.; Howorth, J.; Horsfield, C. J.

    2014-11-15

    Fusion diagnostics that utilise high speed scintillators often need to capture a large area of light with a high degree of time accuracy. Microchannel plate (MCP) photomultiplier tubes (PMTs) are recognised as the leading device for capturing fast optical signals. However, when manufactured in their traditional proximity focused construction, the time response performance is reduced as the active area increases. This is due to two main factors: the capacitance of a large anode and the difficulty of obtaining small pore MCPs with a large area. Collaboration between Photek and AWE has produced prototype devices that combine the excellent time response of small area MCP-PMTs with a large active area by replacing the traditional proximity-gap front section with an electro-optically focused photocathode to MCP. We present results from both single and double MCP devices with a 40 mm diameter active area and show simulations for the 100 mm device being built this year.

  8. Discrete-time linear and nonlinear aerodynamic impulse responses for efficient CFD analyses

    NASA Astrophysics Data System (ADS)

    Silva, Walter Arturo

    This dissertation discusses the mathematical existence and the numerical identification of linear and nonlinear aerodynamic impulse response functions. Differences between continuous-time and discrete-time system theories, which permit the identification and efficient use of these functions, will be detailed. Important input/output definitions and the concept of linear and nonlinear systems with memory will also be discussed. It will be shown that indicial (step or steady) responses (such as Wagner's function), forced harmonic responses (such as Theodorsen's function or those from doublet lattice theory), and responses to random inputs (such as gusts) can all be obtained from an aerodynamic impulse response function. This will establish the aerodynamic discrete-time impulse response function as the most fundamental and computationally efficient aerodynamic function that can be extracted from any given discrete-time, aerodynamic system. The results presented in this dissertation help to unify the understanding of classical two-dimensional continuous-time theories with modern three-dimensional, discrete-time theories. Nonlinear aerodynamic impulse responses are identified using the Volterra theory of nonlinear systems. The theory is described and a discrete-time kernel identification technique is presented. The kernel identification technique is applied to a simple nonlinear circuit for illustrative purposes. The method is then applied to the nonlinear viscous Burger's equation as an example of an application to a simple CFD model. Finally, the method is applied to a three-dimensional aeroelastic model using the CAP-TSD (Computational Aeroelasticity Program - Transonic Small Disturbance) code and then to a two-dimensional model using the CFL3D Navier-Stokes code. Comparisons of accuracy and computational cost savings are presented. Because of its mathematical generality, an important attribute of this methodology is that it is applicable to a wide range of nonlinear

  9. Temperature Responses to Spectral Solar Variability on Decadal Time Scales

    NASA Technical Reports Server (NTRS)

    Cahalan, Robert F.; Wen, Guoyong; Harder, Jerald W.; Pilewskie, Peter

    2010-01-01

    Two scenarios of spectral solar forcing, namely Spectral Irradiance Monitor (SIM)-based out-of-phase variations and conventional in-phase variations, are input to a time-dependent radiative-convective model (RCM), and to the GISS modelE. Both scenarios and models give maximum temperature responses in the upper stratosphere, decreasing to the surface. Upper stratospheric peak-to-peak responses to out-of-phase forcing are approx.0.6 K and approx.0.9 K in RCM and modelE, approx.5 times larger than responses to in-phase forcing. Stratospheric responses are in-phase with TSI and UV variations, and resemble HALOE observed 11-year temperature variations. For in-phase forcing, ocean mixed layer response lags surface air response by approx.2 years, and is approx.0.06 K compared to approx.0.14 K for atmosphere. For out-of-phase forcing, lags are similar, but surface responses are significantly smaller. For both scenarios, modelE surface responses are less than 0.1 K in the tropics, and display similar patterns over oceanic regions, but complex responses over land.

  10. Conceptual Question Response Times in Peer Instruction Classrooms

    ERIC Educational Resources Information Center

    Miller, Kelly; Lasry, Nathaniel; Lukoff, Brian; Schell, Julie; Mazur, Eric

    2014-01-01

    Classroom response systems are widely used in interactive teaching environments as a way to engage students by asking them questions. Previous research on the time taken by students to respond to conceptual questions has yielded insights on how students think and change conceptions. We measure the amount of time students take to respond to…

  11. 4 CFR 201.7 - Timing of responses to requests.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 4 Accounts 1 2010-01-01 2010-01-01 false Timing of responses to requests. 201.7 Section 201.7 Accounts RECOVERY ACCOUNTABILITY AND TRANSPARENCY BOARD PUBLIC INFORMATION AND REQUESTS § 201.7 Timing of... letter or an e-mail confirming the requestor's agreement to pay fees under § 201.8 and providing...

  12. Prospective evaluation of the VITEK MS for the routine identification of bacteria and yeast in the clinical microbiology laboratory: assessment of accuracy of identification and turnaround time.

    PubMed

    Charnot-Katsikas, Angella; Tesic, Vera; Boonlayangoor, Sue; Bethel, Cindy; Frank, Karen M

    2014-02-01

    This study assessed the accuracy of bacterial and yeast identification using the VITEK MS, and the time to reporting of isolates before and after its implementation in routine clinical practice. Three hundred and sixty-two isolates of bacteria and yeast, consisting of a variety of clinical isolates and American Type Culture Collection strains, were tested. Results were compared with reference identifications from the VITEK 2 system and with 16S rRNA sequence analysis. The VITEK MS provided an acceptable identification to species level for 283 (78 %) isolates. Considering organisms for which genus-level identification is acceptable for routine clinical care, 315 isolates (87 %) had an acceptable identification. Six isolates (2 %) were identified incorrectly, five of which were Shigella species. Finally, the time for reporting the identifications was decreased significantly after implementation of the VITEK MS for a total mean reduction in time of 10.52 h (P<0.0001). Overall, accuracy of the VITEK MS was comparable or superior to that from the VITEK 2. The findings were also comparable to other studies examining the accuracy of the VITEK MS, although differences exist, depending on the diversity of species represented as well as on the versions of the databases used. The VITEK MS can be incorporated effectively into routine use in a clinical microbiology laboratory and future expansion of the database should provide improved accuracy for the identification of micro-organisms.

  13. A Conditional Joint Modeling Approach for Locally Dependent Item Responses and Response Times

    ERIC Educational Resources Information Center

    Meng, Xiang-Bin; Tao, Jian; Chang, Hua-Hua

    2015-01-01

    The assumption of conditional independence between the responses and the response times (RTs) for a given person is common in RT modeling. However, when the speed of a test taker is not constant, this assumption will be violated. In this article we propose a conditional joint model for item responses and RTs, which incorporates a covariance…

  14. An extra dimension to decision-making in animals: the three-way trade-off between speed, effort per-unit-time and accuracy.

    PubMed

    de Froment, Adrian J; Rubenstein, Daniel I; Levin, Simon A

    2014-12-01

    The standard view in biology is that all animals, from bumblebees to human beings, face a trade-off between speed and accuracy as they search for resources and mates, and attempt to avoid predators. For example, the more time a forager spends out of cover gathering information about potential food sources the more likely it is to make accurate decisions about which sources are most rewarding. However, when the cost of time spent out of cover rises (e.g. in the presence of a predator) the optimal strategy is for the forager to spend less time gathering information and to accept a corresponding decline in the accuracy of its decisions. We suggest that this familiar picture is missing a crucial dimension: the amount of effort an animal expends on gathering information in each unit of time. This is important because an animal that can respond to changing time costs by modulating its level of effort per-unit-time does not have to accept the same decrease in accuracy that an animal limited to a simple speed-accuracy trade-off must bear in the same situation. Instead, it can direct additional effort towards (i) reducing the frequency of perceptual errors in the samples it gathers or (ii) increasing the number of samples it gathers per-unit-time. Both of these have the effect of allowing it to gather more accurate information within a given period of time. We use a modified version of a canonical model of decision-making (the sequential probability ratio test) to show that this ability to substitute effort for time confers a fitness advantage in the face of changing time costs. We predict that the ability to modulate effort levels will therefore be widespread in nature, and we lay out testable predictions that could be used to detect adaptive modulation of effort levels in laboratory and field studies. Our understanding of decision-making in all species, including our own, will be improved by this more ecologically-complete picture of the three-way tradeoff between time

  15. An Extra Dimension to Decision-Making in Animals: The Three-way Trade-off between Speed, Effort per-Unit-Time and Accuracy

    PubMed Central

    de Froment, Adrian J.; Rubenstein, Daniel I.; Levin, Simon A.

    2014-01-01

    The standard view in biology is that all animals, from bumblebees to human beings, face a trade-off between speed and accuracy as they search for resources and mates, and attempt to avoid predators. For example, the more time a forager spends out of cover gathering information about potential food sources the more likely it is to make accurate decisions about which sources are most rewarding. However, when the cost of time spent out of cover rises (e.g. in the presence of a predator) the optimal strategy is for the forager to spend less time gathering information and to accept a corresponding decline in the accuracy of its decisions. We suggest that this familiar picture is missing a crucial dimension: the amount of effort an animal expends on gathering information in each unit of time. This is important because an animal that can respond to changing time costs by modulating its level of effort per-unit-time does not have to accept the same decrease in accuracy that an animal limited to a simple speed-accuracy trade-off must bear in the same situation. Instead, it can direct additional effort towards (i) reducing the frequency of perceptual errors in the samples it gathers or (ii) increasing the number of samples it gathers per-unit-time. Both of these have the effect of allowing it to gather more accurate information within a given period of time. We use a modified version of a canonical model of decision-making (the sequential probability ratio test) to show that this ability to substitute effort for time confers a fitness advantage in the face of changing time costs. We predict that the ability to modulate effort levels will therefore be widespread in nature, and we lay out testable predictions that could be used to detect adaptive modulation of effort levels in laboratory and field studies. Our understanding of decision-making in all species, including our own, will be improved by this more ecologically-complete picture of the three-way tradeoff between time

  16. Conceptual question response times in Peer Instruction classrooms

    NASA Astrophysics Data System (ADS)

    Miller, Kelly; Lasry, Nathaniel; Lukoff, Brian; Schell, Julie; Mazur, Eric

    2014-12-01

    Classroom response systems are widely used in interactive teaching environments as a way to engage students by asking them questions. Previous research on the time taken by students to respond to conceptual questions has yielded insights on how students think and change conceptions. We measure the amount of time students take to respond to in-class, conceptual questions [ConcepTests (CTs)] in two introductory physics courses taught using Peer Instruction and use item response theory to determine the difficulty of the CTs. We examine response time differences between correct and incorrect answers both before and after the peer discussion for CTs of varying difficulty. We also determine the relationship between response time and student performance on a standardized test of incoming physics knowledge, precourse self-efficacy, and gender. Our data reveal three results of interest. First, response time for correct answers is significantly faster than for incorrect answers, both before and after peer discussion, especially for easy CTs. Second, students with greater incoming physics knowledge and higher self-efficacy respond faster in both rounds. Third, there is no gender difference in response rate after controlling for incoming physics knowledge scores, although males register significantly more attempts before committing to a final answer than do female students. These results provide insight into effective CT pacing during Peer Instruction. In particular, in order to maintain a pace that keeps everyone engaged, students should not be given too much time to respond. When around 80% of the answers are in, the ratio of correct to incorrect responses rapidly approaches levels indicating random guessing and instructors should close the poll.

  17. Modeling operators' emergency response time for chemical processing operations.

    PubMed

    Murray, Susan L; Harputlu, Emrah; Mentzer, Ray A; Mannan, M Sam

    2014-01-01

    Operators have a crucial role during emergencies at a variety of facilities such as chemical processing plants. When an abnormality occurs in the production process, the operator often has limited time to either take corrective actions or evacuate before the situation becomes deadly. It is crucial that system designers and safety professionals can estimate the time required for a response before procedures and facilities are designed and operations are initiated. There are existing industrial engineering techniques to establish time standards for tasks performed at a normal working pace. However, it is reasonable to expect the time required to take action in emergency situations will be different than working at a normal production pace. It is possible that in an emergency, operators will act faster compared to a normal pace. It would be useful for system designers to be able to establish a time range for operators' response times for emergency situations. This article develops a modeling approach to estimate the time standard range for operators taking corrective actions or following evacuation procedures in emergency situations. This will aid engineers and managers in establishing time requirements for operators in emergency situations. The methodology used for this study combines a well-established industrial engineering technique for determining time requirements (predetermined time standard system) and adjustment coefficients for emergency situations developed by the authors. Numerous videos of workers performing well-established tasks at a maximum pace were studied. As an example, one of the tasks analyzed was pit crew workers changing tires as quickly as they could during a race. The operations in these videos were decomposed into basic, fundamental motions (such as walking, reaching for a tool, and bending over) by studying the videos frame by frame. A comparison analysis was then performed between the emergency pace and the normal working pace operations

  18. Effect of fatigue on reaction time, response time, performance time, and kick impact in taekwondo roundhouse kick.

    PubMed

    Sant'Ana, Jader; Franchini, Emerson; da Silva, Vinicius; Diefenthaeler, Fernando

    2016-09-05

    Reaction time and response time are considered important abilities and can potentially affect combat performance. This study investigated the effect of a specific fatigue protocol on reaction time, response time, performance time, and kick impact. Seven male athletes reported to the laboratory on two different days. During day one, athletes performed a specific progressive taekwondo test, and on day two, a protocol for determining reaction time, response time, performance time, and kick impact before and after a time to exhaustion test at an intensity level corresponding to the maximal kick frequency obtained during the specific progressive taekwondo test. Muscle activation from rectus femoris and kick impact of the preferred limb were assessed. No differences were observed for response time and performance time. However, kick impact decreased (43 ± 27 to 13 ± 10 g, p < 0.01) while reaction time increased (145 ± 51 to 223 ± 133 ms, p < 0.05). Moderate correlation was observed between kick impact and response time (r = 0.565; p < 0.01), and kick impact and performance time (r = 0.494; p < 0.05). Results indicate that coaches and athletes may use taekwondo training programmes on coordination-based exercises leading to improve response time and to reduce fatigue effects in order to improve technique effectiveness and enhance the possibilities of scoring in a competitive situation.

  19. Maternal Accuracy and Behavior in Anticipating Children's Responses to Novelty: Relations to Fearful Temperament and Implications for Anxiety Development

    ERIC Educational Resources Information Center

    Kiel, Elizabeth J.; Buss, Kristin A.

    2010-01-01

    Previous research has suggested that mothers' behaviors may serve as a mechanism in the development from toddler fearful temperament to childhood anxiety. The current study examined the maternal characteristic of accuracy in predicting toddlers' distress reactions to novelty in relation to temperament, parenting, and anxiety development.…

  20. Finding a fractional model from frequency and time responses

    NASA Astrophysics Data System (ADS)

    Valério, Duarte; Sá da Costa, José

    2010-04-01

    An existing method for identifying an integer model from frequency data, developed to be used when synthesising second-generation Crone controllers, is adapted to identify fractional order plants. The modification only allows models with poles but no zeros or zeros but no poles. Two application examples are given, one of them showing how the method can also be used when a time response, rather than a frequency response, is available.

  1. Peripheral visual response time and retinal luminance-area relations

    NASA Technical Reports Server (NTRS)

    Haines, R. F.

    1975-01-01

    Experiments were undertaken to elucidate the stimulus luminance-retinal area relationship that underlies response time (RT) behavior. Mean RT was significantly faster to stimuli imaged beyond about 70 deg of arc from the fovea when their luminance was increased by an amount equal to the foveal stimulus luminance multiplied by the cosine of the angle between the peripheral stimuli and the line of sight. This and additional data are discussed in relation to previous psychophysical data and to possible response mechanisms.

  2. Time domains of the hypoxic ventilatory response in ectothermic vertebrates.

    PubMed

    Porteus, Cosima; Hedrick, Michael S; Hicks, James W; Wang, Tobias; Milsom, William K

    2011-04-01

    Over a decade has passed since Powell et al. (Respir Physiol 112:123-134, 1998) described and defined the time domains of the hypoxic ventilatory response (HVR) in adult mammals. These time domains, however, have yet to receive much attention in other vertebrate groups. The initial, acute HVR of fish, amphibians and reptiles serves to minimize the imbalance between oxygen supply and demand. If the hypoxia is sustained, a suite of secondary adjustments occur giving rise to a more long-term balance (acclimatization) that allows the behaviors of normal life. These secondary responses can change over time as a function of the nature of the stimulus (the pattern and intensity of the hypoxic exposure). To add to the complexity of this process, hypoxia can also lead to metabolic suppression (the hypoxic metabolic response) and the magnitude of this is also time dependent. Unlike the original review of Powell et al. (Respir Physiol 112:123-134, 1998) that only considered the HVR in adult animals, we also consider relevant developmental time points where information is available. Finally, in amphibians and reptiles with incompletely divided hearts the magnitude of the ventilatory response will be modulated by hypoxia-induced changes in intra-cardiac shunting that also improve the match between O(2) supply and demand, and these too change in a time-dependent fashion. While the current literature on this topic is reviewed here, it is noted that this area has received little attention. We attempt to redefine time domains in a more 'holistic' fashion that better accommodates research on ectotherms. If we are to distinguish between the genetic, developmental and environmental influences underlying the various ventilatory responses to hypoxia, however, we must design future experiments with time domains in mind.

  3. Monte Carlo Simulation of Response Time for Velocity Modulation Transistors

    NASA Astrophysics Data System (ADS)

    Maezawa, Koichi; Mizutani, Takashi; Tomizawa, Masaaki

    1992-03-01

    We have studied the response time for velocity modulation transistors (VMTs) using particle Monte Carlo simulation. The intrinsic VMT model with zero gate-source spacing was used to avoid the change in total number of electrons due to the difference in source resistances between the two channels. The results show that the response time for VMTs is about half that for ordinary high electron mobility transistors (HEMTs). The remaining factor limiting the response time is the electron redistribution in the channel, which is shown to be caused by the difference in velocity-electric field characteristics in the two channels. A “virtual” VMT model with a single channel, where the impurity concentration is changed abruptly at a certain moment, has also been studied to clarify the effect of electron redistribution.

  4. Optimizing geometric accuracy of four-dimensional CT scans acquired using the wall- and couch-mounted Varian® Real-time Position Management™ camera systems

    PubMed Central

    Irvine, D M; Cole, A J; Hanna, G G; McGarry, C K

    2015-01-01

    Objective: The aim of this study was to identify sources of anatomical misrepresentation owing to the location of camera mounting, tumour motion velocity and image processing artefacts in order to optimize the four-dimensional CT (4DCT) scan protocol and improve geometrical–temporal accuracy. Methods: A phantom with an imaging insert was driven with a sinusoidal superior–inferior motion of varying amplitude and period for 4DCT scanning. The length of a high-density cube within the insert was measured using treatment planning software to determine the accuracy of its spatial representation. Scan parameters were varied, including the tube rotation period and the cine time between reconstructed images. A CT image quality phantom was used to measure various image quality signatures under the scan parameters tested. Results: No significant difference in spatial accuracy was found for 4DCT scans carried out using the wall- or couch-mounted camera for sinusoidal target motion. Greater spatial accuracy was found for 4DCT scans carried out using a tube rotation speed of 0.5 s rather than 1.0 s. The reduction in image quality when using a faster rotation speed was not enough to require an increase in patient dose. Conclusion: The 4DCT accuracy may be increased by optimizing scan parameters, including choosing faster tube rotation speeds. Peak misidentification in the recorded breathing trace may lead to spatial artefacts, and this risk can be reduced by using a couch-mounted infrared camera. Advances in knowledge: This study explicitly shows that 4DCT scan accuracy is improved by scanning with a faster CT tube rotation speed. PMID:25470359

  5. Magnetospheric response and reconfiguration times following IMF By reversals

    NASA Astrophysics Data System (ADS)

    Tenfjord, P.; Østgaard, N.; Strangeway, R.; Haaland, S.; Snekvik, K.; Laundal, K. M.; Reistad, J. P.; Milan, S. E.

    2017-01-01

    The interaction between the interplanetary magnetic field (IMF) and the geomagnetic field at the dayside magnetopause leads to transfer of momentum and energy which changes the magnetospheric configuration, but only after a certain time. In this study we quantify this time, to advance our understanding of the causes for the delayed response of the magnetosphere. We study the response and reconfiguration time of the inner magnetosphere to IMF By reversals. A superposed epoch analysis of magnetic field measurements from four Geostationary Operational Environmental Satellite spacecraft at different local times both for negative to positive IMF By reversals and for positive to negative reversals is presented. The magnetospheric response time at geosynchronous orbit to the sudden change of IMF By is less than 15 (˜10) min from the bow shock (magnetopause) arrival time, while the reconfiguration time is less than 46 (˜41) min. These results are consistent with a By component induced on closed magnetic field lines due to the asymmetric loading of flux following asymmetric dayside reconnection when IMF By≠0. Our results also confirm our earlier studies that nightside reconnection is not required for generating a By component on closed field lines.

  6. The theoretical accuracy of Runge-Kutta time discretizations for the initial boundary value problem: A careful study of the boundary error

    NASA Technical Reports Server (NTRS)

    Carpenter, Mark H.; Gottlieb, David; Abarbanel, Saul; Don, Wai-Sun

    1993-01-01

    The conventional method of imposing time dependent boundary conditions for Runge-Kutta (RK) time advancement reduces the formal accuracy of the space-time method to first order locally, and second order globally, independently of the spatial operator. This counter intuitive result is analyzed in this paper. Two methods of eliminating this problem are proposed for the linear constant coefficient case: (1) impose the exact boundary condition only at the end of the complete RK cycle, (2) impose consistent intermediate boundary conditions derived from the physical boundary condition and its derivatives. The first method, while retaining the RK accuracy in all cases, results in a scheme with much reduced CFL condition, rendering the RK scheme less attractive. The second method retains the same allowable time step as the periodic problem. However it is a general remedy only for the linear case. For non-linear hyperbolic equations the second method is effective only for for RK schemes of third order accuracy or less. Numerical studies are presented to verify the efficacy of each approach.

  7. Linear-scaling time-dependent density-functional theory beyond the Tamm-Dancoff approximation: Obtaining efficiency and accuracy with in situ optimised local orbitals

    NASA Astrophysics Data System (ADS)

    Zuehlsdorff, T. J.; Hine, N. D. M.; Payne, M. C.; Haynes, P. D.

    2015-11-01

    We present a solution of the full time-dependent density-functional theory (TDDFT) eigenvalue equation in the linear response formalism exhibiting a linear-scaling computational complexity with system size, without relying on the simplifying Tamm-Dancoff approximation (TDA). The implementation relies on representing the occupied and unoccupied subspaces with two different sets of in situ optimised localised functions, yielding a very compact and efficient representation of the transition density matrix of the excitation with the accuracy associated with a systematic basis set. The TDDFT eigenvalue equation is solved using a preconditioned conjugate gradient algorithm that is very memory-efficient. The algorithm is validated on a small test molecule and a good agreement with results obtained from standard quantum chemistry packages is found, with the preconditioner yielding a significant improvement in convergence rates. The method developed in this work is then used to reproduce experimental results of the absorption spectrum of bacteriochlorophyll in an organic solvent, where it is demonstrated that the TDA fails to reproduce the main features of the low energy spectrum, while the full TDDFT equation yields results in good qualitative agreement with experimental data. Furthermore, the need for explicitly including parts of the solvent into the TDDFT calculations is highlighted, making the treatment of large system sizes necessary that are well within reach of the capabilities of the algorithm introduced here. Finally, the linear-scaling properties of the algorithm are demonstrated by computing the lowest excitation energy of bacteriochlorophyll in solution. The largest systems considered in this work are of the same order of magnitude as a variety of widely studied pigment-protein complexes, opening up the possibility of studying their properties without having to resort to any semiclassical approximations to parts of the protein environment.

  8. Linear-scaling time-dependent density-functional theory beyond the Tamm-Dancoff approximation: Obtaining efficiency and accuracy with in situ optimised local orbitals

    SciTech Connect

    Zuehlsdorff, T. J. Payne, M. C.; Hine, N. D. M.; Haynes, P. D.

    2015-11-28

    We present a solution of the full time-dependent density-functional theory (TDDFT) eigenvalue equation in the linear response formalism exhibiting a linear-scaling computational complexity with system size, without relying on the simplifying Tamm-Dancoff approximation (TDA). The implementation relies on representing the occupied and unoccupied subspaces with two different sets of in situ optimised localised functions, yielding a very compact and efficient representation of the transition density matrix of the excitation with the accuracy associated with a systematic basis set. The TDDFT eigenvalue equation is solved using a preconditioned conjugate gradient algorithm that is very memory-efficient. The algorithm is validated on a small test molecule and a good agreement with results obtained from standard quantum chemistry packages is found, with the preconditioner yielding a significant improvement in convergence rates. The method developed in this work is then used to reproduce experimental results of the absorption spectrum of bacteriochlorophyll in an organic solvent, where it is demonstrated that the TDA fails to reproduce the main features of the low energy spectrum, while the full TDDFT equation yields results in good qualitative agreement with experimental data. Furthermore, the need for explicitly including parts of the solvent into the TDDFT calculations is highlighted, making the treatment of large system sizes necessary that are well within reach of the capabilities of the algorithm introduced here. Finally, the linear-scaling properties of the algorithm are demonstrated by computing the lowest excitation energy of bacteriochlorophyll in solution. The largest systems considered in this work are of the same order of magnitude as a variety of widely studied pigment-protein complexes, opening up the possibility of studying their properties without having to resort to any semiclassical approximations to parts of the protein environment.

  9. Measuring sequences of keystrokes with jsPsych: Reliability of response times and interkeystroke intervals.

    PubMed

    Pinet, S; Zielinski, C; Mathôt, S; Dufau, S; Alario, F-X; Longcamp, M

    2016-07-13

    Although the precision and reliability of response time (RT) measurements performed via Web-based interfaces have been evaluated, sequences of keystrokes have never been investigated in detail. Keystrokes often occur in much more rapid succession than RTs, and operating systems may interpret successive or concomitant keyboard events according to both automatic and user-based settings. Sequence keystroke timing could thus be more sensitive than single RTs to noise in online measurements. Here, we quantified the precision and reliability of timing measures performed during sequences of keystrokes. We used the JavaScript jsPsych library to create an experiment involving finger-movement sequences, and ran it online with 633 participants. We manipulated the structure of three keystroke motor sequences, targeting a replication of previous findings regarding both RTs and interkeystroke intervals (IKIs). Our online data accurately reproduced the original results and allowed for a novel assessment of demographic variables such as age and gender. In parallel, we also measured the objective timing accuracy of the jsPsych interface by using specialized hardware and software, showing a constant 60-ms delay for RTs and a 0-ms delay for IKIs across the sequences. The distribution of IKIs revealed quantizing for a majority of participants, most likely due to the sampling frequency of their USB keyboards. Overall, these findings indicate that JsPsych provides good reliability and accuracy in sequence keystroke timings for mental chronometry purposes, through online recordings.

  10. Investigation of the trade-off between time window length, classifier update rate and classification accuracy for restorative brain-computer interfaces.

    PubMed

    Darvishi, Sam; Ridding, Michael C; Abbott, Derek; Baumert, Mathias

    2013-01-01

    Recently, the application of restorative brain-computer interfaces (BCIs) has received significant interest in many BCI labs. However, there are a number of challenges, that need to be tackled to achieve efficient performance of such systems. For instance, any restorative BCI needs an optimum trade-off between time window length, classification accuracy and classifier update rate. In this study, we have investigated possible solutions to these problems by using a dataset provided by the University of Graz, Austria. We have used a continuous wavelet transform and the Student t-test for feature extraction and a support vector machine (SVM) for classification. We find that improved results, for restorative BCIs for rehabilitation, may be achieved by using a 750 milliseconds time window with an average classification accuracy of 67% that updates every 32 milliseconds.

  11. Assessing recognition memory using confidence ratings and response times

    PubMed Central

    Kahana, Michael J.

    2016-01-01

    Classification of stimuli into categories (such as ‘old’ and ‘new’ in tests of recognition memory or ‘present’ versus ‘absent’ in signal detection tasks) requires the mapping of internal signals to discrete responses. Introspective judgements about a given choice response are regularly employed in research, legal and clinical settings in an effort to measure the signal that is thought to be the basis of the classification decision. Correlations between introspective judgements and task performance suggest that such ratings often do convey information about internal states that are relevant for a given task, but well-known limitations of introspection call the fidelity of this information into question. We investigated to what extent response times can reveal information usually assessed with explicit confidence ratings. We quantitatively compared response times to confidence ratings in their ability to qualify recognition memory decisions and found convergent results suggesting that much of the information from confidence ratings can be obtained from response times. PMID:27152209

  12. A fourth order accuracy summation-by-parts finite difference scheme for acoustic reverse time migration in boundary-conforming grids

    NASA Astrophysics Data System (ADS)

    Wang, Ying; Zhou, Hui; Yuan, Sanyi; Ye, Yameng

    2017-01-01

    The fourth order accuracy finite difference scheme is known advantageous in reducing memory and improving efficiency. Summation-by-parts finite difference operator is a natural way for wavefield simulation in complicated domains containing surface topography and irregular interfaces. The application of summation-by-parts method guarantees the stability of numerical approximation for heterogeneous media on curvilinear grids. This paper extends the second order summation-by-parts finite difference method to the fourth order case for the discretization of acoustic wave equation and perfect matched layer in boundary-conforming grids. In particular, the implementation of the fourth order method for wavefield simulation and reverse time migration in complicated domains can significantly improve the efficiency and decrease the storage. The elliptic method is applied for boundary-conforming grid generation in complicated domains. Under such grids, the two-dimensional acoustic wave equation in second order displacement formulation is compactly reformulated for forward modeling and reverse time migration, and the symmetric and compact form of perfectly matched layers expressed in a curvilinear coordinate system are applied to suppress artificial reflections. The discretizations of the acoustic wave equation and perfectly matched layer formula are fourth and second order accuracy in space and time respectively, where the spatial discretization satisfies the principle of summation-by-parts and is stable. Numerical experiments are presented to compare the accuracy of the second with fourth order summation-by-parts finite difference methods and to evaluate the efficiency of reverse time migration by using these two methods. As well, comparisons are performed between the fourth order accuracy summation-by-parts finite difference method and central finite difference method to illustrate the stability superiority of summation-by-parts operators.

  13. Error-Induced Blindness: Error Detection Leads to Impaired Sensory Processing and Lower Accuracy at Short Response-Stimulus Intervals.

    PubMed

    Buzzell, George A; Beatty, Paul J; Paquette, Natalie A; Roberts, Daniel M; McDonald, Craig G

    2017-03-15

    Empirical evidence indicates that detecting one's own mistakes can serve as a signal to improve task performance. However, little work has focused on how task constraints, such as the response-stimulus interval (RSI), influence post-error adjustments. In the present study, event-related potential (ERP) and behavioral measures were used to investigate the time course of error-related processing while humans performed a difficult visual discrimination task. We found that error commission resulted in a marked reduction in both task performance and sensory processing on the following trial when RSIs were short, but that such impairments were not detectable at longer RSIs. Critically, diminished sensory processing at short RSIs, indexed by the stimulus-evoked P1 component, was predicted by an ERP measure of error processing, the Pe component. A control analysis ruled out a general lapse in attention or mind wandering as being predictive of subsequent reductions in sensory processing; instead, the data suggest that error detection causes an attentional bottleneck, which can diminish sensory processing on subsequent trials that occur in short succession. The findings demonstrate that the neural system dedicated to monitoring and improving behavior can, paradoxically, at times be the source of performance failures.SIGNIFICANCE STATEMENT The performance-monitoring system is a network of brain regions dedicated to monitoring behavior to adjust task performance when necessary. Previous research has demonstrated that activation of the performance monitoring system following incorrect decisions serves to improve future task performance. However, the present study provides evidence that, when perceptual decisions must be made rapidly (within approximately half a second of each other), activation of the performance-monitoring system is predictive of impaired task-related attention on the subsequent trial. The data illustrate that the cognitive demands imposed by error processing

  14. Time-domain response of the ARIANNA detector

    NASA Astrophysics Data System (ADS)

    Barwick, S. W.; Berg, E. C.; Besson, D. Z.; Duffin, T.; Hanson, J. C.; Klein, S. R.; Kleinfelder, S. A.; Piasecki, M.; Ratzlaff, K.; Reed, C.; Roumi, M.; Stezelberger, T.; Tatar, J.; Walker, J.; Young, R.; Zou, L.

    2015-03-01

    The Antarctic Ross Ice Shelf Antenna Neutrino Array (ARIANNA) is a high-energy neutrino detector designed to record the Askaryan electric field signature of cosmogenic neutrino interactions in ice. To understand the inherent radio-frequency (RF) neutrino signature, the time-domain response of the ARIANNA RF receiver must be measured. ARIANNA uses Create CLP5130-2N log-periodic dipole arrays (LPDAs). The associated effective height operator converts incident electric fields to voltage waveforms at the LDPA terminals. The effective height versus time and incident angle was measured, along with the associated response of the ARIANNA RF amplifier. The results are verified by correlating to field measurements in air and ice, using oscilloscopes. Finally, theoretical models for the Askaryan electric field are combined with the detector response to predict the neutrino signature.

  15. 40 CFR 1601.24 - Timing of responses to requests.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 32 2010-07-01 2010-07-01 false Timing of responses to requests. 1601.24 Section 1601.24 Protection of Environment CHEMICAL SAFETY AND HAZARD INVESTIGATION BOARD PROCEDURES FOR DISCLOSURE OF RECORDS UNDER THE FREEDOM OF INFORMATION ACT Procedures for Requesting...

  16. 45 CFR 612.5 - Timing of responses to requests.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ....5 Public Welfare Regulations Relating to Public Welfare (Continued) NATIONAL SCIENCE FOUNDATION AVAILABILITY OF RECORDS AND INFORMATION § 612.5 Timing of responses to requests. (a) In general. NSF ordinarily... government activity, if made by a person primarily engaged in disseminating information. (2) For example,...

  17. 5 CFR 1820.4 - Timing of responses to requests.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 5 Administrative Personnel 3 2014-01-01 2014-01-01 false Timing of responses to requests. 1820.4 Section 1820.4 Administrative Personnel OFFICE OF SPECIAL COUNSEL FREEDOM OF INFORMATION ACT REQUESTS... expedited processing must submit a statement, certified to be true and correct to the best of that...

  18. 49 CFR 701.7 - Timing of responses to requests.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... PASSENGER CORPORATION (AMTRAK) AMTRAK FREEDOM OF INFORMATION ACT PROGRAM § 701.7 Timing of responses to... Freedom of Information Office. (2) A request for records shall be considered to have been received on the..., certified to be true and correct to the best of that person's knowledge and belief, explaining in detail...

  19. 5 CFR 1820.4 - Timing of responses to requests.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 5 Administrative Personnel 3 2010-01-01 2010-01-01 false Timing of responses to requests. 1820.4 Section 1820.4 Administrative Personnel OFFICE OF SPECIAL COUNSEL FREEDOM OF INFORMATION ACT REQUESTS... expedited processing must submit a statement, certified to be true and correct to the best of that...

  20. 18 CFR 1301.5 - Timing of responses to requests.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 18 Conservation of Power and Water Resources 2 2013-04-01 2012-04-01 true Timing of responses to requests. 1301.5 Section 1301.5 Conservation of Power and Water Resources TENNESSEE VALLEY AUTHORITY... practicable speed, with another agency having a substantial interest in the determination of the request...

  1. 48 CFR 1505.203 - Publicizing and response time.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 48 Federal Acquisition Regulations System 6 2010-10-01 2010-10-01 true Publicizing and response time. 1505.203 Section 1505.203 Federal Acquisition Regulations System ENVIRONMENTAL PROTECTION AGENCY..., elect to transmit a synopsis to the Commerce Business Daily (CBD) of a proposed contract action...

  2. Separability of Item and Person Parameters in Response Time Models.

    ERIC Educational Resources Information Center

    Van Breukelen, Gerard J. P.

    1997-01-01

    Discusses two forms of separability of item and person parameters in the context of response time models. The first is "separate sufficiency," and the second is "ranking independence." For each form a theorem stating sufficient conditions is proved. The two forms are shown to include several cases of models from psychometric…

  3. From Zero to Sixty: Calibrating Real-Time Responses

    ERIC Educational Resources Information Center

    Koulis, Theodoro; Ramsay, James O.; Levitin, Daniel J.

    2008-01-01

    Recent advances in data recording technology have given researchers new ways of collecting on-line and continuous data for analyzing input-output systems. For example, continuous response digital interfaces are increasingly used in psychophysics. The statistical problem related to these input-output systems reduces to linking time-varying…

  4. 40 CFR 89.316 - Analyzer leakage and response time.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Equipment Provisions § 89.316 Analyzer leakage and response time. (a) Vacuum side leak check. (1) Any location within the analysis system where a vacuum leak could affect the test results must be checked. (2) The maximum allowable leakage rate on the vacuum side is 0.5 percent of the in-use flow rate for...

  5. Modeling Information Accumulation in Psychological Tests Using Item Response Times

    ERIC Educational Resources Information Center

    Ranger, Jochen; Kuhn, Jörg-Tobias

    2015-01-01

    In this article, a latent trait model is proposed for the response times in psychological tests. The latent trait model is based on the linear transformation model and subsumes popular models from survival analysis, like the proportional hazards model and the proportional odds model. Core of the model is the assumption that an unspecified monotone…

  6. Processing Time Shifts Affects the Execution of Motor Responses

    ERIC Educational Resources Information Center

    Sell, Andrea J.; Kaschak, Michael P.

    2011-01-01

    We explore whether time shifts in text comprehension are represented spatially. Participants read sentences involving past or future events and made sensibility judgment responses in one of two ways: (1) moving toward or away from their body and (2) pressing the toward or away buttons without moving. Previous work suggests that spatial…

  7. Distinct Response Time Distributions in Attention Deficit Hyperactivity Disorder Subtypes

    ERIC Educational Resources Information Center

    Querne, Laurent; Berquin, Patrick

    2009-01-01

    Objective: To address the issue of response time (RT) profiles in hyperactive-impulsive (ADHD-HI), inattentive (ADHD-IA), and combined (ADHD-C) subtypes of ADHD. We hypothesized that children with ADHD-HI should respond more rapidly than children without ADHD and children with ADHD-IA and ADHD-C should respond more slowly than children without…

  8. Timing and causality in the generation of learned eyelid responses.

    PubMed

    Sánchez-Campusano, Raudel; Gruart, Agnès; Delgado-García, José M

    2011-01-01

    The cerebellum-red nucleus-facial motoneuron (Mn) pathway has been reported as being involved in the proper timing of classically conditioned eyelid responses. This special type of associative learning serves as a model of event timing for studying the role of the cerebellum in dynamic motor control. Here, we have re-analyzed the firing activities of cerebellar posterior interpositus (IP) neurons and orbicularis oculi (OO) Mns in alert behaving cats during classical eyeblink conditioning, using a delay paradigm. The aim was to revisit the hypothesis that the IP neurons (IPns) can be considered a neuronal phase-modulating device supporting OO Mns firing with an emergent timing mechanism and an explicit correlation code during learned eyelid movements. Optimized experimental and computational tools allowed us to determine the different causal relationships (temporal order and correlation code) during and between trials. These intra- and inter-trial timing strategies expanding from sub-second range (millisecond timing) to longer-lasting ranges (interval timing) expanded the functional domain of cerebellar timing beyond motor control. Interestingly, the results supported the above-mentioned hypothesis. The causal inferences were influenced by the precise motor and pre-motor spike timing in the cause-effect interval, and, in addition, the timing of the learned responses depended on cerebellar-Mn network causality. Furthermore, the timing of CRs depended upon the probability of simulated causal conditions in the cause-effect interval and not the mere duration of the inter-stimulus interval. In this work, the close relation between timing and causality was verified. It could thus be concluded that the firing activities of IPns may be related more to the proper performance of ongoing CRs (i.e., the proper timing as a consequence of the pertinent causality) than to their generation and/or initiation.

  9. Comparison of several methods for obtaining the time response of linear systems to either a unit impulse or arbitrary input from frequency-response data

    NASA Technical Reports Server (NTRS)

    Donegan, James J; Huss, Carl R

    1957-01-01

    Several methods of obtaining the time response of Linear systems to either a unit impulse or an arbitrary input from frequency-response data are described and compared. Comparisons indicate that all the methods give good accuracy when applied to a second-order system; the main difference is the required computing time. The methods generally classified as inverse Laplace transform methods were found to be most effective in determining the response to a unit impulse from frequency-response data of higher order systems. Some discussion and examples are given of the use of such methods as flight-data-analysis techniques in predicting loads and motions of a flexible aircraft on the basis of simple calculations when the aircraft frequency response is known.

  10. Monitoring Ambulation of Patients in Geriatric Rehabilitation Wards: The Accuracy of Clinicians' Prediction of Patients' Walking Time

    ERIC Educational Resources Information Center

    Cheung, Vivian H. Y.; Salih, Salih A.; Crouch, Alisa; Karunanithi, Mohanraj K.; Gray, Len

    2012-01-01

    The aim of this study is to determine whether clinicians' estimates of patients' walking time agree with those determined by accelerometer devices. The walking time was measured using a waist-mounted accelerometer device everyday during the patients' waking hours. At each weekly meeting, clinicians estimated the patients' average daily walking…

  11. Aircraft Fault Detection Using Real-Time Frequency Response Estimation

    NASA Technical Reports Server (NTRS)

    Grauer, Jared A.

    2016-01-01

    A real-time method for estimating time-varying aircraft frequency responses from input and output measurements was demonstrated. The Bat-4 subscale airplane was used with NASA Langley Research Center's AirSTAR unmanned aerial flight test facility to conduct flight tests and collect data for dynamic modeling. Orthogonal phase-optimized multisine inputs, summed with pilot stick and pedal inputs, were used to excite the responses. The aircraft was tested in its normal configuration and with emulated failures, which included a stuck left ruddervator and an increased command path latency. No prior knowledge of a dynamic model was used or available for the estimation. The longitudinal short period dynamics were investigated in this work. Time-varying frequency responses and stability margins were tracked well using a 20 second sliding window of data, as compared to a post-flight analysis using output error parameter estimation and a low-order equivalent system model. This method could be used in a real-time fault detection system, or for other applications of dynamic modeling such as real-time verification of stability margins during envelope expansion tests.

  12. Time-lapse and slow-motion tracking of temperature changes: response time of a thermometer

    NASA Astrophysics Data System (ADS)

    Moggio, L.; Onorato, P.; Gratton, L. M.; Oss, S.

    2017-03-01

    We propose the use of a smartphone based time-lapse and slow-motion video techniques together with tracking analysis as valuable tools for investigating thermal processes such as the response time of a thermometer. The two simple experimental activities presented here, suitable also for high school and undergraduate students, allow one to measure in a simple yet rigorous way the response time of an alcohol thermometer and show its critical dependence on the properties of the surrounding environment giving insight into instrument characteristics, heat transfer and thermal equilibrium concepts.

  13. Controlled image design: The measurement of time-frequency responses

    NASA Astrophysics Data System (ADS)

    Walker, R.; Eng, C.

    1995-03-01

    This report describes the measurement of acoustic events in a three-dimensional measurement domain. An outline of the general theoretical background is followed by a description of the special requirements for the measurement of short-term acoustic responses in rooms. The results of measurements on an experimental synthesis of a single room reflection are also presented. It is shown that the measurement and presentation of the result in terms of amplitude/time, amplitude/frequency, and three-dimensional time/frequency/amplitude responses accurately portray the true situation, within the theoretical limitations of the Fourier transform. It is shown that the achievable time and frequency resolutions are probably just adequate for the measurement of those effects thought to be important for the perception of the stereophonic illusion.

  14. Dose-time-response modeling using negative binomial distribution.

    PubMed

    Roy, Munmun; Choudhury, Kanak; Islam, M M; Matin, M A

    2013-01-01

    People exposed to certain diseases are required to be treated with a safe and effective dose level of a drug. In epidemiological studies to find out an effective dose level, different dose levels are applied to the exposed and a certain number of cures is observed. Negative binomial distribution is considered to fit overdispersed Poisson count data. This study investigates the time effect on the response at different time points as well as at different dose levels. The point estimation and confidence bands for ED(100p)(t) and LT(100p)(d) are formulated in closed form for the proposed dose-time-response model with the negative binomial distribution. Numerical illustrations are carried out in order to check the performance level of the proposed model.

  15. The Time Course Effect of Moderate Intensity Exercise on Response Execution and Response Inhibition

    ERIC Educational Resources Information Center

    Joyce, Jennifer; Graydon, Jan; McMorris, Terry; Davranche, Karen

    2009-01-01

    This research aimed to investigate the time course effect of a moderate steady-state exercise session on response execution and response inhibition using a stop-task paradigm. Ten participants performed a stop-signal task whilst cycling at a carefully controlled workload intensity (40% of maximal aerobic power), immediately following exercise and…

  16. Adaptive Responses to Prochloraz Exposure That Alter Dose-Response and Time-Course Behaviors

    EPA Science Inventory

    Dose response and time-course (DRTC) are, along with exposure, the major determinants of health risk. Adaptive changes within exposed organisms in response to environmental stress are common, and alter DRTC behaviors to minimize the effects caused by stressors. In this project, ...

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

    PubMed Central

    Stout, Erik E; Beloozerova, Irina N

    2013-01-01

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

  18. An Implicit Measure of Associations with Mental Illness versus Physical Illness: Response Latency Decomposition and Stimuli Differential Functioning in Relation to IAT Order of Associative Conditions and Accuracy

    PubMed Central

    Mannarini, Stefania; Boffo, Marilisa

    2014-01-01

    The present study aimed at the definition of a latent measurement dimension underlying an implicit measure of automatic associations between the concept of mental illness and the psychosocial and biogenetic causal explanatory attributes. To this end, an Implicit Association Test (IAT) assessing the association between the Mental Illness and Physical Illness target categories to the Psychological and Biologic attribute categories, representative of the causal explanation domains, was developed. The IAT presented 22 stimuli (words and pictures) to be categorized into the four categories. After 360 university students completed the IAT, a Many-Facet Rasch Measurement (MFRM) modelling approach was applied. The model specified a person latency parameter and a stimulus latency parameter. Two additional parameters were introduced to denote the order of presentation of the task associative conditions and the general response accuracy. Beyond the overall definition of the latent measurement dimension, the MFRM was also applied to disentangle the effect of the task block order and the general response accuracy on the stimuli response latency. Further, the MFRM allowed detecting any differential functioning of each stimulus in relation to both block ordering and accuracy. The results evidenced: a) the existence of a latency measurement dimension underlying the Mental Illness versus Physical Illness - Implicit Association Test; b) significant effects of block order and accuracy on the overall latency; c) a differential functioning of specific stimuli. The results of the present study can contribute to a better understanding of the functioning of an implicit measure of semantic associations with mental illness and give a first blueprint for the examination of relevant issues in the development of an IAT. PMID:25000406

  19. Time dependency of craving and response inhibition during nicotine abstinence

    PubMed Central

    Tsaur, Stephen; Strasser, Andrew A.; Souprountchouk, Valentina; Evans, Gretchen C.; Ashare, Rebecca L.

    2015-01-01

    Background Nicotine withdrawal produces increased craving for cigarettes and deficits in response inhibition, and these withdrawal symptoms are predictive of relapse. Although it is well-established that these symptoms emerge early during abstinence, there is mixed evidence regarding whether they occur simultaneously. Given the importance of the early withdrawal period, this study examined craving and response inhibition at 24h and 72h abstinence. Methods Twenty-one non-treatment seeking adult smokers were evaluated at baseline, 24h, and 72h abstinence for craving (Questionnaire on Smoking Urges – Brief) and response inhibition (Stop Signal Task, Stroop Task, Continuous Performance Task). Generalized linear regression models were used for primary outcomes, and Pearson correlations for examining the association between craving and response inhibition. Results Factor 2 craving (anticipated relief of negative affect) increased from baseline to 24h abstinent (p=0.004), which subsided by 72h (p=0.08). Deficits in response inhibition measured by the Stop Signal Task were observed at 72h (p=0.046), but not 24h (p=0.318). No correlation was found between response inhibition and craving at any time point (p-values>0.19), except between the Stroop Task and factor 1 craving at baseline (p=0.025). Conclusions Factor 2 craving peaked at 24h, whereas deficits in response inhibition did not emerge until 72h, indicating that need to target craving and cognitive function during early abstinence may not occur simultaneously. Further characterizing the time course of withdrawal symptoms may guide development of targeted treatments for smoking cessation. PMID:26052265

  20. High-accuracy and long-range Brillouin optical time-domain analysis sensor based on the combination of pulse prepump technique and complementary coding

    NASA Astrophysics Data System (ADS)

    Sun, Qiao; Tu, Xiaobo; Lu, Yang; Sun, Shilin; Meng, Zhou

    2016-06-01

    A Brillouin optical time-domain analysis (BOTDA) sensor that combines the conventional complementary coding with the pulse prepump technique for high-accuracy and long-range distributed sensing is implemented and analyzed. The employment of the complementary coding provides an enhanced signal-to-noise ratio (SNR) of the sensing system and an extended sensing distance, and the measurement time is also reduced compared with a BOTDA sensor using linear coding. The combination of pulse prepump technique enables the establishment of a preactivated acoustic field in each pump pulse of the complementary codeword, which ensures measurements of high spatial resolution and high frequency accuracy. The feasibility of the prepumped complementary coding is analyzed theoretically and experimentally. The experiments are carried out beyond 50-km single-mode fiber, and experimental results show the capabilities of the proposed scheme to achieve 1-m spatial resolution with temperature and strain resolutions equal to ˜1.6°C and ˜32 μɛ, and 2-m spatial resolution with temperature and strain resolutions equal to ˜0.3°C and ˜6 μɛ, respectively. A longer sensing distance with the same spatial resolution and measurement accuracy can be achieved through increasing the code length of the prepumped complementary code.

  1. Ampoule failure sensor time response testing: Experiments 2 and 3

    NASA Technical Reports Server (NTRS)

    Johnson, M. L.; Watring, D. A.

    1994-01-01

    The response time of an ampoule failure sensor exposed to a liquid or vapor gallium-arsenide (GaAs) and the corresponding breach time of the containing cartridge is investigated. The experiments were conducted in niobium-hafnium (WC-103) cartridges with an exterior silicide coating. These cartridges were built to flight specifications that were used in NASA's Crystal Growth Furnace during the first United States Microgravity Laboratory (USML-1) mission. The ampoule failure sensor is a chemical fuse made from a metal with which the semiconductor material reacts more rapidly than it does with the containing cartridge. In these experiments a platinum metal was used for the manufacture of the sensors. This technical report discusses the response time of two different sensor designs. The first design utilizes a helical wrapped wire and the second uses a single bare wire element. Experimental results indicate that both sensors are adequate in sensing the presence of molten or vapor GaAs with the latter having a 2-minute longer response time. In both experiments, the containing cartridge was breached within 185 minutes after ampoule rupture.

  2. Ultimate response time of high electron mobility transistors

    NASA Astrophysics Data System (ADS)

    Rudin, Sergey; Rupper, Greg; Shur, Michael

    2015-05-01

    We present theoretical studies of the response time of the two-dimensional gated electron gas to femtosecond pulses. Our hydrodynamic simulations show that the device response to a short pulse or a step-function signal is either smooth or oscillating time-decay at low and high mobility, μ, values, respectively. At small gate voltage swings, U0 = Ug - Uth, where Ug is the gate voltage and Uth is the threshold voltage, such that μU0/L < vs, where L is the channel length and vs is the effective electron saturation velocity, the decay time in the low mobility samples is on the order of L2/(μU0), in agreement with the analytical drift model. However, the decay is preceded by a delay time on the order of L/s, where s is the plasma wave velocity. This delay is the ballistic transport signature in collision-dominated devices, which becomes important during very short time periods. In the high mobility devices, the period of the decaying oscillations is on the order of the plasma wave velocity transit time. Our analysis shows that short channel field effect transistors operating in the plasmonic regime can meet the requirements for applications as terahertz detectors, mixers, delay lines, and phase shifters in ultra high-speed wireless communication circuits.

  3. Ultimate response time of high electron mobility transistors

    SciTech Connect

    Rudin, Sergey; Rupper, Greg; Shur, Michael

    2015-05-07

    We present theoretical studies of the response time of the two-dimensional gated electron gas to femtosecond pulses. Our hydrodynamic simulations show that the device response to a short pulse or a step-function signal is either smooth or oscillating time-decay at low and high mobility, μ, values, respectively. At small gate voltage swings, U{sub 0} = U{sub g} − U{sub th}, where U{sub g} is the gate voltage and U{sub th} is the threshold voltage, such that μU{sub 0}/L < v{sub s}, where L is the channel length and v{sub s} is the effective electron saturation velocity, the decay time in the low mobility samples is on the order of L{sup 2}/(μU{sub 0}), in agreement with the analytical drift model. However, the decay is preceded by a delay time on the order of L/s, where s is the plasma wave velocity. This delay is the ballistic transport signature in collision-dominated devices, which becomes important during very short time periods. In the high mobility devices, the period of the decaying oscillations is on the order of the plasma wave velocity transit time. Our analysis shows that short channel field effect transistors operating in the plasmonic regime can meet the requirements for applications as terahertz detectors, mixers, delay lines, and phase shifters in ultra high-speed wireless communication circuits.

  4. Smart Device-Supported BDS/GNSS Real-Time Kinematic Positioning for Sub-Meter-Level Accuracy in Urban Location-Based Services

    PubMed Central

    Wang, Liang; Li, Zishen; Zhao, Jiaojiao; Zhou, Kai; Wang, Zhiyu; Yuan, Hong

    2016-01-01

    Using mobile smart devices to provide urban location-based services (LBS) with sub-meter-level accuracy (around 0.5 m) is a major application field for future global navigation satellite system (GNSS) development. Real-time kinematic (RTK) positioning, which is a widely used GNSS-based positioning approach, can improve the accuracy from about 10–20 m (achieved by the standard positioning services) to about 3–5 cm based on the geodetic receivers. In using the smart devices to achieve positioning with sub-meter-level accuracy, a feasible solution of combining the low-cost GNSS module and the smart device is proposed in this work and a user-side GNSS RTK positioning software was developed from scratch based on the Android platform. Its real-time positioning performance was validated by BeiDou Navigation Satellite System/Global Positioning System (BDS/GPS) combined RTK positioning under the conditions of a static and kinematic (the velocity of the rover was 50–80 km/h) mode in a real urban environment with a SAMSUNG Galaxy A7 smartphone. The results show that the fixed-rates of ambiguity resolution (the proportion of epochs of ambiguities fixed) for BDS/GPS combined RTK in the static and kinematic tests were about 97% and 90%, respectively, and the average positioning accuracies (RMS) were better than 0.15 m (horizontal) and 0.25 m (vertical) for the static test, and 0.30 m (horizontal) and 0.45 m (vertical) for the kinematic test. PMID:28009835

  5. Smart Device-Supported BDS/GNSS Real-Time Kinematic Positioning for Sub-Meter-Level Accuracy in Urban Location-Based Services.

    PubMed

    Wang, Liang; Li, Zishen; Zhao, Jiaojiao; Zhou, Kai; Wang, Zhiyu; Yuan, Hong

    2016-12-21

    Using mobile smart devices to provide urban location-based services (LBS) with sub-meter-level accuracy (around 0.5 m) is a major application field for future global navigation satellite system (GNSS) development. Real-time kinematic (RTK) positioning, which is a widely used GNSS-based positioning approach, can improve the accuracy from about 10-20 m (achieved by the standard positioning services) to about 3-5 cm based on the geodetic receivers. In using the smart devices to achieve positioning with sub-meter-level accuracy, a feasible solution of combining the low-cost GNSS module and the smart device is proposed in this work and a user-side GNSS RTK positioning software was developed from scratch based on the Android platform. Its real-time positioning performance was validated by BeiDou Navigation Satellite System/Global Positioning System (BDS/GPS) combined RTK positioning under the conditions of a static and kinematic (the velocity of the rover was 50-80 km/h) mode in a real urban environment with a SAMSUNG Galaxy A7 smartphone. The results show that the fixed-rates of ambiguity resolution (the proportion of epochs of ambiguities fixed) for BDS/GPS combined RTK in the static and kinematic tests were about 97% and 90%, respectively, and the average positioning accuracies (RMS) were better than 0.15 m (horizontal) and 0.25 m (vertical) for the static test, and 0.30 m (horizontal) and 0.45 m (vertical) for the kinematic test.

  6. Accuracy of the evaluation method for alkaline agents’ bactericidal efficacies in solid, and the required time of bacterial inactivation

    PubMed Central

    HAKIM, Hakimullah; TOYOFUKU, Chiharu; OTA, Mari; SUZUKI, Mayuko; KOMURA, Miyuki; YAMADA, Masashi; ALAM, Md. Shahin; SANGSRIRATANAKUL, Natthanan; SHOHAM, Dany; TAKEHARA, Kazuaki

    2016-01-01

    An alkaline agent, namely food additive grade calcium hydroxide (FdCa (OH)2) in the powder form, was evaluated for its bactericidal efficacies in chicken feces at pH 13. The point for this evaluation was neutralization of the alkaline agent’s pH at the time of bacterial recovery, since otherwise the results are substantially misleading. Without neutralization of the FdCa (OH)2 pH, the spiked bacteria were killed within min at the time of recovery in aqueous phase, but not in the solid form in feces, hence, it has been demonstrated that when bacteria were in solid, it took longer time than in liquid for the alkaline agent to inactivate them down to the acceptable level (≥3 log10 CFU/ml). PMID:27890906

  7. Planck 2013 results. VII. HFI time response and beams

    NASA Astrophysics Data System (ADS)

    Planck Collaboration; Ade, P. A. R.; Aghanim, N.; Armitage-Caplan, C.; Arnaud, M.; Ashdown, M.; Atrio-Barandela, F.; Aumont, J.; Baccigalupi, C.; Banday, A. J.; Barreiro, R. B.; Battaner, E.; Benabed, K.; Benoît, A.; Benoit-Lévy, A.; Bernard, J.-P.; Bersanelli, M.; Bielewicz, P.; Bobin, J.; Bock, J. J.; Bond, J. R.; Borrill, J.; Bouchet, F. R.; Bowyer, J. W.; Bridges, M.; Bucher, M.; Burigana, C.; Cardoso, J.-F.; Catalano, A.; Challinor, A.; Chamballu, A.; Chary, R.-R.; Chiang, H. C.; Chiang, L.-Y.; Christensen, P. R.; Church, S.; Clements, D. L.; Colombi, S.; Colombo, L. P. L.; Couchot, F.; Coulais, A.; Crill, B. P.; Curto, A.; Cuttaia, F.; Danese, L.; Davies, R. D.; de Bernardis, P.; de Rosa, A.; de Zotti, G.; Delabrouille, J.; Delouis, J.-M.; Désert, F.-X.; Diego, J. M.; Dole, H.; Donzelli, S.; Doré, O.; Douspis, M.; Dunkley, J.; Dupac, X.; Efstathiou, G.; Enßlin, T. A.; Eriksen, H. K.; Finelli, F.; Forni, O.; Frailis, M.; Fraisse, A. A.; Franceschi, E.; Galeotta, S.; Ganga, K.; Giard, M.; Giraud-Héraud, Y.; González-Nuevo, J.; Górski, K. M.; Gratton, S.; Gregorio, A.; Gruppuso, A.; Gudmundsson, J. E.; Haissinski, J.; Hansen, F. K.; Hanson, D.; Harrison, D.; Henrot-Versillé, S.; Hernández-Monteagudo, C.; Herranz, D.; Hildebrandt, S. R.; Hivon, E.; Hobson, M.; Holmes, W. A.; Hornstrup, A.; Hou, Z.; Hovest, W.; Huffenberger, K. M.; Jaffe, A. H.; Jaffe, T. R.; Jones, W. C.; Juvela, M.; Keihänen, E.; Keskitalo, R.; Kisner, T. S.; Kneissl, R.; Knoche, J.; Knox, L.; Kunz, M.; Kurki-Suonio, H.; Lagache, G.; Lamarre, J.-M.; Lasenby, A.; Laureijs, R. J.; Lawrence, C. R.; Leonardi, R.; Leroy, C.; Lesgourgues, J.; Liguori, M.; Lilje, P. B.; Linden-Vørnle, M.; López-Caniego, M.; Lubin, P. M.; Macías-Pérez, J. F.; MacTavish, C. J.; Maffei, B.; Mandolesi, N.; Maris, M.; Marshall, D. J.; Martin, P. G.; Martínez-González, E.; Masi, S.; Massardi, M.; Matarrese, S.; Matsumura, T.; Matthai, F.; Mazzotta, P.; McGehee, P.; Melchiorri, A.; Mendes, L.; Mennella, A.; Migliaccio, M.; Mitra, S.; Miville-Deschênes, M.-A.; Moneti, A.; Montier, L.; Morgante, G.; Mortlock, D.; Munshi, D.; Murphy, J. A.; Naselsky, P.; Nati, F.; Natoli, P.; Netterfield, C. B.; Nørgaard-Nielsen, H. U.; Noviello, F.; Novikov, D.; Novikov, I.; Osborne, S.; Oxborrow, C. A.; Paci, F.; Pagano, L.; Pajot, F.; Paoletti, D.; Pasian, F.; Patanchon, G.; Perdereau, O.; Perotto, L.; Perrotta, F.; Piacentini, F.; Piat, M.; Pierpaoli, E.; Pietrobon, D.; Plaszczynski, S.; Pointecouteau, E.; Polegre, A. M.; Polenta, G.; Ponthieu, N.; Popa, L.; Poutanen, T.; Pratt, G. W.; Prézeau, G.; Prunet, S.; Puget, J.-L.; Rachen, J. P.; Reinecke, M.; Remazeilles, M.; Renault, C.; Ricciardi, S.; Riller, T.; Ristorcelli, I.; Rocha, G.; Rosset, C.; Roudier, G.; Rowan-Robinson, M.; Rusholme, B.; Sandri, M.; Santos, D.; Sauvé, A.; Savini, G.; Scott, D.; Shellard, E. P. S.; Spencer, L. D.; Starck, J.-L.; Stolyarov, V.; Stompor, R.; Sudiwala, R.; Sureau, F.; Sutton, D.; Suur-Uski, A.-S.; Sygnet, J.-F.; Tauber, J. A.; Tavagnacco, D.; Terenzi, L.; Tomasi, M.; Tristram, M.; Tucci, M.; Umana, G.; Valenziano, L.; Valiviita, J.; Van Tent, B.; Vielva, P.; Villa, F.; Vittorio, N.; Wade, L. A.; Wandelt, B. D.; Yvon, D.; Zacchei, A.; Zonca, A.

    2014-11-01

    This paper characterizes the effective beams, the effective beam window functions and the associated errors for the Planck High Frequency Instrument (HFI) detectors. The effective beam is theangular response including the effect of the optics, detectors, data processing and the scan strategy. The window function is the representation of this beam in the harmonic domain which is required to recover an unbiased measurement of the cosmic microwave background angular power spectrum. The HFI is a scanning instrument and its effective beams are the convolution of: a) the optical response of the telescope and feeds; b) the processing of the time-ordered data and deconvolution of the bolometric and electronic transfer function; and c) the merging of several surveys to produce maps. The time response transfer functions are measured using observations of Jupiter and Saturn and by minimizing survey difference residuals. The scanning beam is the post-deconvolution angular response of the instrument, and is characterized with observations of Mars. The main beam solid angles are determined to better than 0.5% at each HFI frequency band. Observations of Jupiter and Saturn limit near sidelobes (within 5°) to about 0.1% of the total solid angle. Time response residuals remain as long tails in the scanning beams, but contribute less than 0.1% of the total solid angle. The bias and uncertainty in the beam products are estimated using ensembles of simulated planet observations that include the impact of instrumental noise and known systematic effects. The correlation structure of these ensembles is well-described by five error eigenmodes that are sub-dominant to sample variance and instrumental noise in the harmonic domain. A suite of consistency tests provide confidence that the error model represents a sufficient description of the data. The total error in the effective beam window functions is below 1% at 100 GHz up to multipole ℓ ~ 1500, and below 0.5% at 143 and 217 GHz up to

  8. Time-delayed model of immune response in plants.

    PubMed

    Neofytou, G; Kyrychko, Y N; Blyuss, K B

    2016-01-21

    In the studies of plant infections, the plant immune response is known to play an essential role. In this paper we derive and analyse a new mathematical model of plant immune response with particular account for post-transcriptional gene silencing (PTGS). Besides biologically accurate representation of the PTGS dynamics, the model explicitly includes two time delays to represent the maturation time of the growing plant tissue and the non-instantaneous nature of the PTGS. Through analytical and numerical analysis of stability of the steady states of the model we identify parameter regions associated with recovery and resistant phenotypes, as well as possible chronic infections. Dynamics of the system in these regimes is illustrated by numerical simulations of the model.

  9. Time-dependent response of filamentary composite spherical pressure vessels

    NASA Technical Reports Server (NTRS)

    Dozier, J. D.

    1983-01-01

    A filamentary composite spherical pressure vessel is modeled as a pseudoisotropic (or transversely isotropic) composite shell, with the effects of the liner and fill tubes omitted. Equations of elasticity, macromechanical and micromechanical formulations, and laminate properties are derived for the application of an internally pressured spherical composite vessel. Viscoelastic properties for the composite matrix are used to characterize time-dependent behavior. Using the maximum strain theory of failure, burst pressure and critical strain equations are formulated, solved in the Laplace domain with an associated elastic solution, and inverted back into the time domain using the method of collocation. Viscoelastic properties of HBFR-55 resin are experimentally determined and a Kevlar/HBFR-55 system is evaluated with a FORTRAN program. The computed reduction in burst pressure with respect to time indicates that the analysis employed may be used to predict the time-dependent response of a filamentary composite spherical pressure vessel.

  10. Physical response of light-time gravitational wave detectors

    NASA Astrophysics Data System (ADS)

    Koop, Michael J.; Finn, Lee Samuel

    2014-09-01

    Gravitational wave detectors are typically described as responding to gravitational wave metric perturbations, which are gauge-dependent and—correspondingly—unphysical quantities. This is particularly true for ground-based interferometric detectors, like LIGO, space-based detectors, like LISA and its derivatives, spacecraft Doppler tracking detectors, and pulsar timing array detectors. The description of gravitational waves, and a gravitational wave detector's response, to the unphysical metric perturbation has lead to a proliferation of false analogies and descriptions regarding how these detectors function, and true misunderstandings of the physical character of gravitational waves. Here we provide a fully physical and gauge-invariant description of the response of a wide class of gravitational wave detectors in terms of the Riemann curvature, the physical quantity that describes gravitational phenomena in general relativity. In the limit of high frequency gravitational waves, the Riemann curvature separates into two independent gauge-invariant quantities: a "background" curvature contribution and a "wave" curvature contribution. In this limit the gravitational wave contribution to the detector response reduces to an integral of the gravitational wave contribution of the curvature along the unperturbed photon path between components of the detector. The description presented here provides an unambiguous physical description of what a gravitational wave detector measures and how it operates, a simple means of computing corrections to a detectors response owing to general detector motion, a straightforward way of connecting the results of numerical relativity simulations to gravitational wave detection, and a basis for a general and fully relativistic pulsar timing formula.

  11. Collecting Response Times using Amazon Mechanical Turk and Adobe Flash

    PubMed Central

    Simcox, Travis; Fiez, Julie A.

    2017-01-01

    Crowdsourcing systems like Amazon's Mechanical Turk (AMT) allow data to be collected from a large sample of people in a short amount of time. This use has garnered considerable interest from behavioral scientists. So far, most experiments conducted on AMT have focused on survey-type instruments because of difficulties inherent in running many experimental paradigms over the Internet. This article investigated the viability of presenting stimuli and collecting response times using Adobe Flash to run ActionScript 3 code in conjunction with AMT. First, the timing properties of Adobe Flash were investigated using a phototransistor and two desktop computers running under several conditions mimicking those that may be present in research using AMT. This experiment revealed some strengths and weaknesses of the timing capabilities of this method. Next, a flanker task and a lexical decision task implemented in Adobe Flash were administered to participants recruited with AMT. The expected effects in these tasks were replicated. Power analyses were conducted to describe the number of participants needed to replicate these effects. A questionnaire was used to investigate previously undescribed computer use habits of 100 participants on AMT. We conclude that a Flash program in conjunction with AMT can be successfully used for running many experimental paradigms that rely on response times, although experimenters must understand the limitations of the method. PMID:23670340

  12. Traffic model by braking capability and response time

    NASA Astrophysics Data System (ADS)

    Lee, Hyun Keun; Kim, Jeenu; Kim, Youngho; Lee, Choong-Ki

    2015-06-01

    We propose a microscopic traffic model where the update velocity is determined by the deceleration capacity and response time. It is found that there is a class of collisions that cannot be distinguished by simply comparing the stop positions. The model generates the safe, comfortable, and efficient traffic flow in numerical simulations with a reasonable values of the parameters, and this is analytically supported. Our approach provides a new perspective in modeling traffic-flow safety and worrying situations like lane changing.

  13. Accuracy of automatic matching of Catphan 504 phantom in cone-beam computed tomography for tube current-exposure time product.

    PubMed

    Won, Hui-Su; Chung, Jin-Beom; Choi, Byung-Don; Park, Jin-Hong; Hwang, Do-Guwn

    2016-11-08

    The purpose of this study is to evaluate the accuracy of automatic matching in cone-beam computed tomography (CBCT) images relative to the reduction of total tube current-exposure time product (mAs) for the X-ray imaging (XI) system. The CBCT images were acquired with the Catphan 504 phantom various total mAs ratios such as 1.00, 0.83, 0.67, 0.57, and 0.50. For studying the automatic match-ing accuracy, the phantom images were acquired with a six-dimensional shifting table. The image quality and correction of automatic matching were compared. With a decreasing total mAs ratio, the noise of the images increased and the low-contrast resolution decreased, while the accuracy of the automatic matching did not change. Therefore, this study shows that a change of the total mAs while acquiring CBCT images has no effect on the automatic matching of Catphan 504 phantom in XI system.

  14. Influence of internal standard charge state on the accuracy of mass measurements in orthogonal acceleration time-of-flight mass spectrometers.

    PubMed

    Charles, Laurence

    2008-01-01

    Accuracy of mass measurements performed in orthogonal acceleration time-of-flight (oa-TOF) mass spectrometers highly depends on the quality of the signal and the internal calibration. The use of two reference compounds which bracket the targeted unknown, give rise to ions with sufficient signal-to-noise ratio while avoiding detector saturation and produce signals of similar intensity as compared to the target is a common requirement which allow a 5 ppm accuracy on a routine basis. Ion charge state is demonstrated here to be an additional and particularly critical parameter. Using internal references of lower charge state than the target ion systematically yielded overestimated data. Errors measured for quadruply charged molecules were in the range 16-18 ppm when mass calibrants were singly charged ions while accuracy was below 5 ppm when references and target ions were in the same charge state. Magnitude of errors was found to increase with the difference in charge state. This phenomenon arises from the orthogonal acceleration of ions in the TOF analyzer, an interface implemented in all TOF mass spectrometers to accommodate continuous beam ionization sources.

  15. Evaluating precision and accuracy when quantifying different endogenous control reference genes in maize using real-time PCR.

    PubMed

    Scholdberg, Tandace A; Norden, Tim D; Nelson, Daishia D; Jenkins, G Ronald

    2009-04-08

    The agricultural biotechnology industry routinely utilizes real-time quantitative PCR (RT-qPCR) for the detection of biotechnology-derived traits in plant material, particularly for meeting the requirements of legislative mandates that rely upon the trace detection of DNA. Quantification via real-time RT-qPCR in plant species involves the measurement of the copy number of a taxon-specific, endogenous control gene exposed to the same manipulations as the target gene prior to amplification. The International Organization for Standardization (ISO 21570:2005) specifies that the copy number of an endogenous reference gene be used for normalizing the concentration (expressed as a % w/w) of a trait-specific target gene when using RT-qPCR. For this purpose, the copy number of a constitutively expressed endogenous reference gene in the same sample is routinely monitored. Real-time qPCR was employed to evaluate the predictability and performance of commonly used endogenous control genes (starch synthase, SSIIb-2, SSIIb-3; alcohol dehydrogenase, ADH; high-mobility group, HMG; zein; and invertase, IVR) used to detect biotechnology-derived traits in maize. The data revealed relatively accurate and precise amplification efficiencies when isogenic maize was compared to certified reference standards, but highly variable results when 23 nonisogenic maize cultivars were compared to an IRMM Bt-11 reference standard. Identifying the most suitable endogenous control gene, one that amplifies consistently and predictably across different maize cultivars, and implementing this as an internationally recognized standard would contribute toward harmonized testing of biotechnology-derived traits in maize.

  16. Influence of the Helicopter Time Domain Electromagnetic System Off-Time Response by the Transmitter Assembly

    NASA Astrophysics Data System (ADS)

    Vetrov, A.; Mejzr, I.

    2010-12-01

    While developing a new Helicopter Time Domain Electromagnetic system (P-THEM), Pico Envirotec Inc (PEI) has studied the effect of the transmitter assembly on the acquired data. The P-THEM system consists of a loop-transmitter assembly, powered by a motor generator, 3-axis coil receiver attached at the midpoint of a tow cable and an additional Z-axis (dB/dt) receiver installed on the rear section of the transmitter loop. The system is towed by a helicopter on a 230 foot long tow cable. The transmitter loop is designed to produce a peak magnetic moment of approximately 250,000 NIA with a base frequency of 30 Hz (adjustable to 25Hz) and a quarter length duty cycle (4 ms on-time). The secondary field acquired with a dB/dt receiver coil consists of a ground response and a system response: SF=Rg+Rsys, where SF - the secondary field, Rg - ground response, Rsys - system response. The system itself, especially the transmitter assembly, being a conductor in an induced magnetic field, creates a magnetic anomaly. The influence of the transmitter assembly anomaly on the received signal depends on the position of the receiver coil against the transmitter, the intensity of on-time pulse and transmitter electro-magnetic properties. At the same time, the ground response acquired with a receiver coil depends on the length and the moment of transmitter pulse, as well as the position and distance of the receiver coil from the ground. This can be for vertical field (Z) receiver coil described as RXz(t)=e(t)pz(t)Rgz(t)+d(t)k(t)j(t)TXz(t), where RXz(t) - receiver response, e(t) - elevation of the receiver over the ground, pz(t) - horizontal projection of the receiver coil, Rgz(t) - vertical component of ground response, d(t) - distance (elevation) between the receiver coil and the transmitter loop, k(t) - the position of the receiver in the transmitter field, j(t) - the transmitter assembly electromagnetic properties, TXz(t) -transmitter field (Primary field on-time, and transmitter

  17. Electromagnetic Real-Time Tumor Position Monitoring and Dynamic Multileaf Collimator Tracking Using a Siemens 160 MLC: Geometric and Dosimetric Accuracy of an Integrated System

    SciTech Connect

    Krauss, Andreas; Nill, Simeon; Tacke, Martin; Oelfke, Uwe

    2011-02-01

    Purpose: Dynamic multileaf collimator tracking represents a promising method for high-precision radiotherapy to moving tumors. In the present study, we report on the integration of electromagnetic real-time tumor position monitoring into a multileaf collimator-based tracking system. Methods and Materials: The integrated system was characterized in terms of its geometric and radiologic accuracy. The former was assessed from portal images acquired during radiation delivery to a phantom in tracking mode. The tracking errors were calculated from the positions of the tracking field and of the phantom as extracted from the portal images. Radiologic accuracy was evaluated from film dosimetry performed for conformal and intensity-modulated radiotherapy applied to different phantoms moving on sinusoidal trajectories. A static radiation delivery to the nonmoving target served as a reference for the delivery to the moving phantom with and without tracking applied. Results: Submillimeter tracking accuracy was observed for two-dimensional target motion despite the relatively large system latency of 500 ms. Film dosimetry yielded almost complete recovery of a circular dose distribution with tracking in two dimensions applied: 2%/2 mm gamma-failure rates could be reduced from 59.7% to 3.3%. For single-beam intensity-modulated radiotherapy delivery, accuracy was limited by the finite leaf width. A 2%/2 mm gamma-failure rate of 15.6% remained with tracking applied. Conclusion: The integrated system we have presented marks a major step toward the clinical implementation of high-precision dynamic multileaf collimator tracking. However, several challenges such as irregular motion traces or a thorough quality assurance still need to be addressed.

  18. Real-time Pricing Demand Response in Operations

    SciTech Connect

    Widergren, Steven E.; Marinovici, Maria C.; Berliner, Teri; Graves, Alan

    2012-07-26

    Abstract—Dynamic pricing schemes have been implemented in commercial and industrial application settings, and recently they are getting attention for application to residential customers. Time-of-use and critical-peak-pricing rates are in place in various regions and are being piloted in many more. These programs are proving themselves useful for balancing energy during peak periods; however, real-time (5 minute) pricing signals combined with automation in end-use systems have the potential to deliver even more benefits to operators and consumers. Besides system peak shaving, a real-time pricing system can contribute demand response based on the locational marginal price of electricity, reduce load in response to a generator outage, and respond to local distribution system capacity limiting situations. The US Department of Energy (DOE) is teaming with a mid-west electricity service provider to run a distribution feeder-based retail electricity market that negotiates with residential automation equipment and clears every 5 minutes, thus providing a signal for lowering or raising electric consumption based on operational objectives of economic efficiency and reliability. This paper outlines the capability of the real-time pricing system and the operational scenarios being tested as the system is rolled-out starting in the first half of 2012.

  19. Comparison of data transformation procedures to enhance topographical accuracy in time-series analysis of the human EEG.

    PubMed

    Hauk, O; Keil, A; Elbert, T; Müller, M M

    2002-01-30

    We describe a methodology to apply current source density (CSD) and minimum norm (MN) estimation as pre-processing tools for time-series analysis of single trial EEG data. The performance of these methods is compared for the case of wavelet time-frequency analysis of simulated gamma-band activity. A reasonable comparison of CSD and MN on the single trial level requires regularization such that the corresponding transformed data sets have similar signal-to-noise ratios (SNRs). For region-of-interest approaches, it should be possible to optimize the SNR for single estimates rather than for the whole distributed solution. An effective implementation of the MN method is described. Simulated data sets were created by modulating the strengths of a radial and a tangential test dipole with wavelets in the frequency range of the gamma band, superimposed with simulated spatially uncorrelated noise. The MN and CSD transformed data sets as well as the average reference (AR) representation were subjected to wavelet frequency-domain analysis, and power spectra were mapped for relevant frequency bands. For both CSD and MN, the influence of noise can be sufficiently suppressed by regularization to yield meaningful information, but only MN represents both radial and tangential dipole sources appropriately as single peaks. Therefore, when relating wavelet power spectrum topographies to their neuronal generators, MN should be preferred.

  20. Prospects for high accuracy time dissemination and synchronization using coded radar pulses from a low-earth orbiting spacecraft

    NASA Technical Reports Server (NTRS)

    Detoma, Edoardo V.; Dionisio, C.

    1995-01-01

    The radar (an acronym for radio detection and ranging) is an instrument developed just before the WW-II to precisely measure the position of an object (target) in space. This is done by emitting a narrow pulse of electromagnetic energy in the RF spectrum, receiving the return echo and measuring the time of flight in the two-way path from the emitter to the target. The propagation delay provides a measure of the range to the target, which is not in itself sufficient to uniquely locate the position of the same in space. However, if a directional antenna is used, the direction of the echo can be assessed by the antenna pointing angles. In this way the position of the target can be uniquely determined in space. How well this can be done is a function of the resolution of the measurements performed (range and direction, i.e.: angles); in turn, the resolution will dictate the time and frequency requirements of the reference oscillator.

  1. Prediction of Pharmacological and Xenobiotic Responses to Drugs Based on Time Course Gene Expression Profiles

    PubMed Central

    Hu, LeLe; Feng, KaiYan; Li, Yi-Xue; Cai, Yu-Dong

    2009-01-01

    More and more people are concerned by the risk of unexpected side effects observed in the later steps of the development of new drugs, either in late clinical development or after marketing approval. In order to reduce the risk of the side effects, it is important to look out for the possible xenobiotic responses at an early stage. We attempt such an effort through a prediction by assuming that similarities in microarray profiles indicate shared mechanisms of action and/or toxicological responses among the chemicals being compared. A large time course microarray database derived from livers of compound-treated rats with thirty-four distinct pharmacological and toxicological responses were studied. The mRMR (Minimum-Redundancy-Maximum-Relevance) method and IFS (Incremental Feature Selection) were used to select a compact feature set (141 features) for the reduction of feature dimension and improvement of prediction performance. With these 141 features, the Leave-one-out cross-validation prediction accuracy of first order response using NNA (Nearest Neighbor Algorithm) was 63.9%. Our method can be used for pharmacological and xenobiotic responses prediction of new compounds and accelerate drug development. PMID:19956587

  2. Effectiveness of slow motion video compared to real time video in improving the accuracy and consistency of subjective gait analysis in dogs.

    PubMed

    Lane, D M; Hill, S A; Huntingford, J L; Lafuente, P; Wall, R; Jones, K A

    2015-01-01

    Objective measures of canine gait quality via force plates, pressure mats or kinematic analysis are considered superior to subjective gait assessment (SGA). Despite research demonstrating that SGA does not accurately detect subtle lameness, it remains the most commonly performed diagnostic test for detecting lameness in dogs. This is largely because the financial, temporal and spatial requirements for existing objective gait analysis equipment makes this technology impractical for use in general practice. The utility of slow motion video as a potential tool to augment SGA is currently untested. To evaluate a more accessible way to overcome the limitations of SGA, a slow motion video study was undertaken. Three experienced veterinarians reviewed video footage of 30 dogs, 15 with a diagnosis of primary limb lameness based on history and physical examination, and 15 with no indication of limb lameness based on history and physical examination. Four different videos were made for each dog, demonstrating each dog walking and trotting in real time, and then again walking and trotting in 50% slow motion. For each video, the veterinary raters assessed both the degree of lameness, and which limb(s) they felt represented the source of the lameness. Spearman's rho, Cramer's V, and t-tests were performed to determine if slow motion video increased either the accuracy or consistency of raters' SGA relative to real time video. Raters demonstrated no significant increase in consistency or accuracy in their SGA of slow motion video relative to real time video. Based on these findings, slow motion video does not increase the consistency or accuracy of SGA values. Further research is required to determine if slow motion video will benefit SGA in other ways.

  3. Effectiveness of slow motion video compared to real time video in improving the accuracy and consistency of subjective gait analysis in dogs

    PubMed Central

    Lane, D.M.; Hill, S.A.; Huntingford, J.L.; Lafuente, P.; Wall, R.; Jones, K.A.

    2015-01-01

    Objective measures of canine gait quality via force plates, pressure mats or kinematic analysis are considered superior to subjective gait assessment (SGA). Despite research demonstrating that SGA does not accurately detect subtle lameness, it remains the most commonly performed diagnostic test for detecting lameness in dogs. This is largely because the financial, temporal and spatial requirements for existing objective gait analysis equipment makes this technology impractical for use in general practice. The utility of slow motion video as a potential tool to augment SGA is currently untested. To evaluate a more accessible way to overcome the limitations of SGA, a slow motion video study was undertaken. Three experienced veterinarians reviewed video footage of 30 dogs, 15 with a diagnosis of primary limb lameness based on history and physical examination, and 15 with no indication of limb lameness based on history and physical examination. Four different videos were made for each dog, demonstrating each dog walking and trotting in real time, and then again walking and trotting in 50% slow motion. For each video, the veterinary raters assessed both the degree of lameness, and which limb(s) they felt represented the source of the lameness. Spearman’s rho, Cramer’s V, and t-tests were performed to determine if slow motion video increased either the accuracy or consistency of raters’ SGA relative to real time video. Raters demonstrated no significant increase in consistency or accuracy in their SGA of slow motion video relative to real time video. Based on these findings, slow motion video does not increase the consistency or accuracy of SGA values. Further research is required to determine if slow motion video will benefit SGA in other ways. PMID:26623383

  4. Camera-based three-dimensional real-time particle tracking at kHz rates and Ångström accuracy

    PubMed Central

    Daldrop, Peter; Joo, Sihwa; Otto, Oliver; Keyser, Ulrich F.; Seidel, Ralf

    2014-01-01

    Optical and magnetic tweezers are widely employed to probe the mechanics and activity of individual biomolecular complexes. They rely on micrometer-sized particles to detect molecular conformational changes from the particle position. Real-time particle tracking with Ångström accuracy has so far been only achieved using laser detection through photodiodes. Here we demonstrate that camera-based imaging can provide a similar performance for all three dimensions. Particle imaging at kHz rates is combined with real-time data processing being accelerated by a graphics processing unit. For particles that are fixed in the sample cell we can detect 3 Å sized steps that are introduced by cell translations at rates of 10 Hz, while for DNA-tethered particles 5 Å steps at 1 Hz can be resolved. Moreover, 20 particles can be tracked in parallel with comparable accuracy. Our approach provides a simple and robust way for high-resolution tweezers experiments using multiple particles at a time. PMID:25565216

  5. Computerized assessment of pedophilic sexual interest through self-report and viewing time: reliability, validity, and classification accuracy of the affinity program.

    PubMed

    Mokros, Andreas; Gebhard, Michael; Heinz, Volker; Marschall, Roland W; Nitschke, Joachim; Glasgow, David V; Gress, Carmen L Z; Laws, D Richard

    2013-06-01

    Affinity is a computerized assessment tool that combines viewing time and self-report measures of sexual interest. The present study was designed to assess the diagnostic properties of Affinity with respect to sexual interest in prepubescent children. Reliability of both self-report and viewing time components was estimated to be high. The group profile of a sample of pedophilic adult male child molesters (n = 42, all of whom admitted their offenses) differed from the group profiles of male community controls (n = 95) and male nonsexual offenders (n = 27), respectively. More specifically, both ratings and viewing times for images showing small children or prejuvenile children were significantly higher within the child molester sample than in either of the other two groups, attesting to the validity of the measures. Overall classification accuracy, however, was mediocre: A multivariate classification routine yielded 50% sensitivity for child molester status at the cost of 13% false positives. The implications for forensic use of Affinity are discussed.

  6. High-accuracy and real-time 3D positioning, tracking system for medical imaging applications based on 3D digital image correlation

    NASA Astrophysics Data System (ADS)

    Xue, Yuan; Cheng, Teng; Xu, Xiaohai; Gao, Zeren; Li, Qianqian; Liu, Xiaojing; Wang, Xing; Song, Rui; Ju, Xiangyang; Zhang, Qingchuan

    2017-01-01

    This paper presents a system for positioning markers and tracking the pose of a rigid object with 6 degrees of freedom in real-time using 3D digital image correlation, with two examples for medical imaging applications. Traditional DIC method was improved to meet the requirements of the real-time by simplifying the computations of integral pixel search. Experiments were carried out and the results indicated that the new method improved the computational efficiency by about 4-10 times in comparison with the traditional DIC method. The system was aimed for orthognathic surgery navigation in order to track the maxilla segment after LeFort I osteotomy. Experiments showed noise for the static point was at the level of 10-3 mm and the measurement accuracy was 0.009 mm. The system was demonstrated on skin surface shape evaluation of a hand for finger stretching exercises, which indicated a great potential on tracking muscle and skin movements.

  7. Item Difficulty and Interviewer Knowledge Effects on the Accuracy and Consistency of Examinee Response Processes in Verbal Reports

    ERIC Educational Resources Information Center

    Leighton, Jacqueline P.

    2013-01-01

    The Standards for Educational and Psychological Testing indicate that multiple sources of validity evidence should be used to support the interpretation of test scores. In the past decade, examinee response processes, as a source of validity evidence, have received increased attention. However, there have been relatively few methodological studies…

  8. Effects of Differential Reinforcement of Short Latencies on Response Latency, Task Completion, and Accuracy of an Adolescent with Autism

    ERIC Educational Resources Information Center

    Donohue, Melanie M.; Casey, Laura Baylot; Bicard, David F.; Bicard, Sara E.

    2012-01-01

    Children with Autism Spectrum Disorder (ASD) are faced with many challenging behaviors that could impede their learning. One commonly reported problem behavior is noncompliance, which is often defined as a delay in response (latency), decrease in rate of responding (fluency), or failure to complete a task. This failure to comply in an appropriate…

  9. The accuracy of timed maximum local anaesthetic dose calculations with an electronic calculator, nomogram, and pen and paper.

    PubMed

    Walker, J D; Williams, N; Williams, D J

    2017-02-24

    Forty anaesthetists calculated maximum permissible doses of eight local anaesthetic formulations for simulated patients three times with three methods: an electronic calculator; nomogram; and pen and paper. Correct dose calculations with the nomogram (85/120) were more frequent than with the calculator (71/120) or pen and paper (57/120), Bayes Factor 4 and 287, p = 0.01 and p = 0.0003, respectively. The rates of calculations at least 120% the recommended dose with each method were different, Bayes Factor 7.9, p = 0.0007: 14/120 with the calculator; 5/120 with the nomogram; 13/120 with pen and paper. The median (IQR [range]) speed of calculation with pen and paper, 38.0 (25.0-56.3 [5-142]) s, was slower than with the calculator, 24.5 (17.8-37.5 [6-204]) s, p = 0.0001, or nomogram, 23.0 (18.0-29.0 [4-100]) s, p = 1 × 10(-7) . Local anaesthetic dose calculations with the nomogram were more accurate than with an electronic calculator or pen and paper and were faster than with pen and paper.

  10. Collecting psycholinguistic response time data using Amazon mechanical Turk.

    PubMed

    Enochson, Kelly; Culbertson, Jennifer

    2015-01-01

    Researchers in linguistics and related fields have recently begun exploiting online crowd-sourcing tools, like Amazon Mechanical Turk (AMT), to gather behavioral data. While this method has been successfully validated for various offline measures--grammaticality judgment or other forced-choice tasks--its use for mainstream psycholinguistic research remains limited. This is because psycholinguistic effects are often dependent on relatively small differences in response times, and there remains some doubt as to whether precise timing measurements can be gathered over the web. Here we show that three classic psycholinguistic effects can in fact be replicated using AMT in combination with open-source software for gathering response times client-side. Specifically, we find reliable effects of subject definiteness, filler-gap dependency processing, and agreement attraction in self-paced reading tasks using approximately the same numbers of participants and/or trials as similar laboratory studies. Our results suggest that psycholinguists can and should be taking advantage of AMT and similar online crowd-sourcing marketplaces as a fast, low-resource alternative to traditional laboratory research.

  11. Collecting Psycholinguistic Response Time Data Using Amazon Mechanical Turk

    PubMed Central

    Enochson, Kelly; Culbertson, Jennifer

    2015-01-01

    Researchers in linguistics and related fields have recently begun exploiting online crowd-sourcing tools, like Amazon Mechanical Turk (AMT), to gather behavioral data. While this method has been successfully validated for various offline measures—grammaticality judgment or other forced-choice tasks—its use for mainstream psycholinguistic research remains limited. This is because psycholinguistic effects are often dependent on relatively small differences in response times, and there remains some doubt as to whether precise timing measurements can be gathered over the web. Here we show that three classic psycholinguistic effects can in fact be replicated using AMT in combination with open-source software for gathering response times client-side. Specifically, we find reliable effects of subject definiteness, filler-gap dependency processing, and agreement attraction in self-paced reading tasks using approximately the same numbers of participants and/or trials as similar laboratory studies. Our results suggest that psycholinguists can and should be taking advantage of AMT and similar online crowd-sourcing marketplaces as a fast, low-resource alternative to traditional laboratory research. PMID:25822348

  12. Time kinetics of the endocrine response to acute psychological stress.

    PubMed

    Richter, S D; Schürmeyer, T H; Schedlowski, M; Hädicke, A; Tewes, U; Schmidt, R E; Wagner, T O

    1996-05-01

    A first-time parachute jump was chosen as a model to evaluate the endocrine response to acute psychological stress. In 43 inexperienced tandem parachutists, blood was drawn continuously from 2 h before to 1 h after the jump and analyzed at 10-min intervals for plasma concentrations of epinephrine (E), norepinephrine (NE), cortisol, GH, PRL, and TSH. In addition, heart rate was recorded throughout the experiment. There was a significant increase in heart rate and E concentrations during the jump itself. NE, cortisol, GH, PRL, and TSH peaked with a latency of 10-20 min. Apart from cortisol and TSH concentrations, which were still elevated 1 h after the stress event, plasma levels of the other endocrine variables normalized within 1 h following the jump. Statistically significant cross-correlations could be observed between E and NE (r = 0.60, no time lag) and between E and PRL (r = 0.58, 10-min time lag) only. Even in a very homogenous group of subjects and under well-controlled conditions, endocrine responses to acute psychological stress show considerable variations.

  13. Reproducibility and accuracy of body composition assessments in mice by dual energy x-ray absorptiometry and time domain nuclear magnetic resonance.

    PubMed

    Halldorsdottir, Solveig; Carmody, Jill; Boozer, Carol N; Leduc, Charles A; Leibel, Rudolph L

    2009-01-01

    OBJECTIVE: To assess the accuracy and reproducibility of dual-energy absorptiometry (DXA; PIXImus(™)) and time domain nuclear magnetic resonance (TD-NMR; Bruker Optics) for the measurement of body composition of lean and obese mice. SUBJECTS AND MEASUREMENTS: Thirty lean and obese mice (body weight range 19-67 g) were studied. Coefficients of variation for repeated (x 4) DXA and NMR scans of mice were calculated to assess reproducibility. Accuracy was assessed by comparing DXA and NMR results of ten mice to chemical carcass analyses. Accuracy of the respective techniques was also assessed by comparing DXA and NMR results obtained with ground meat samples to chemical analyses. Repeated scans of 10-25 gram samples were performed to test the sensitivity of the DXA and NMR methods to variation in sample mass. RESULTS: In mice, DXA and NMR reproducibility measures were similar for fat tissue mass (FTM) (DXA coefficient of variation [CV]=2.3%; and NMR CV=2.8%) (P=0.47), while reproducibility of lean tissue mass (LTM) estimates were better for DXA (1.0%) than NMR (2.2%) (

    accuracy, in mice, DXA overestimated (vs chemical composition) LTM (+1.7 ± 1.3 g [SD], ~ 8%, P <0.001) as well as FTM (+2.0 ± 1.2 g, ~ 46%, P <0.001). NMR estimated LTM and FTM virtually identical to chemical composition analysis (LTM: -0.05 ± 0.5 g, ~0.2%, P =0.79) (FTM: +0.02 ± 0.7 g, ~15%, P =0.93). DXA and NMR-determined LTM and FTM measurements were highly correlated with the corresponding chemical analyses (r(2)=0.92 and r(2)=0.99 for DXA LTM and FTM, respectively; r(2)=0.99 and r(2)=0.99 for NMR LTM and FTM, respectively.) Sample mass did not affect accuracy in assessing chemical composition of small ground meat samples by either DXA or NMR. CONCLUSION: DXA and NMR provide comparable levels of reproducibility in measurements of body composition lean and obese mice. While DXA and NMR measures are highly correlated with chemical analysis measures, DXA consistently

  14. Reproducibility and accuracy of body composition assessments in mice by dual energy x-ray absorptiometry and time domain nuclear magnetic resonance

    PubMed Central

    Halldorsdottir, Solveig; Carmody, Jill; Boozer, Carol N.; Leduc, Charles A.; Leibel, Rudolph L.

    2011-01-01

    Objective To assess the accuracy and reproducibility of dual-energy absorptiometry (DXA; PIXImus™) and time domain nuclear magnetic resonance (TD-NMR; Bruker Optics) for the measurement of body composition of lean and obese mice. Subjects and measurements Thirty lean and obese mice (body weight range 19–67 g) were studied. Coefficients of variation for repeated (x 4) DXA and NMR scans of mice were calculated to assess reproducibility. Accuracy was assessed by comparing DXA and NMR results of ten mice to chemical carcass analyses. Accuracy of the respective techniques was also assessed by comparing DXA and NMR results obtained with ground meat samples to chemical analyses. Repeated scans of 10–25 gram samples were performed to test the sensitivity of the DXA and NMR methods to variation in sample mass. Results In mice, DXA and NMR reproducibility measures were similar for fat tissue mass (FTM) (DXA coefficient of variation [CV]=2.3%; and NMR CV=2.8%) (P=0.47), while reproducibility of lean tissue mass (LTM) estimates were better for DXA (1.0%) than NMR (2.2%) (

    accuracy, in mice, DXA overestimated (vs chemical composition) LTM (+1.7 ± 1.3 g [SD], ~ 8%, P <0.001) as well as FTM (+2.0 ± 1.2 g, ~ 46%, P <0.001). NMR estimated LTM and FTM virtually identical to chemical composition analysis (LTM: −0.05 ± 0.5 g, ~0.2%, P =0.79) (FTM: +0.02 ± 0.7 g, ~15%, P =0.93). DXA and NMR-determined LTM and FTM measurements were highly correlated with the corresponding chemical analyses (r2=0.92 and r2=0.99 for DXA LTM and FTM, respectively; r2=0.99 and r2=0.99 for NMR LTM and FTM, respectively.) Sample mass did not affect accuracy in assessing chemical composition of small ground meat samples by either DXA or NMR. Conclusion DXA and NMR provide comparable levels of reproducibility in measurements of body composition lean and obese mice. While DXA and NMR measures are highly correlated with chemical analysis measures, DXA consistently overestimates LTM

  15. Accuracy of MRI for prediction of response to neo-adjuvant chemotherapy in triple negative breast cancer compared to other subtypes of breast cancer

    PubMed Central

    Bansal, Gaurav J; Santosh, Divya

    2016-01-01

    Purpose: The aim of this study was to compare the accuracy of magnetic resonance imaging (MRI) for the prediction of response to neo-adjuvant chemotherapy in triple negative (TN) breast cancer, with respect to other subtypes. Materials and Methods: There were a total of 1610 breast cancers diagnosed between March 2009 and August 2014, out of which 82 patients underwent MRI before and after neo-adjuvant chemotherapy but just before surgery. TN cancers were analyzed with respect to others subtypes. Accuracy of MRI for prediction of pathological complete response was compared between different subtypes by obtaining receiver operating characteristic (ROC) curves. The Statistical Package for the Social Sciences version 21 was used for all data analysis, with P value of 0.05 as statistically significant. Results: Out of 82 patients, 29 were luminal (HR+/HER2−), 23 were TN (HR−, HER2−), 11 were HER2 positive (HR−, HER2+), and 19 were of hybrid subtype (HR+/HER2+). TN cancers presented as masses on the pre-chemotherapy MRI scan, were grade 3 on histopathology, and showed concentric shrinkage following chemotherapy. TN cancers were more likely to have both imaging and pathological complete response following chemotherapy (P = 0.055) in contrast to luminal cancers, which show residual cancer. ROC curves were constructed for the prediction of pathological complete response with MRI. For the TN subgroup, MR had a sensitivity of 0.745 and specificity of 0.700 (P = 0.035), with an area under curve of 0.745 (95% confidence interval: 0.526–0.965), which was significantly better compared to other subtypes. Conclusion: TN breast cancers present as masses and show concentric shrinkage following chemotherapy. MRI is most accurate in predicting response to chemotherapy in the TN group, compared to others subtypes. MRI underestimates residual disease in luminal cancers. PMID:28104942

  16. SU-E-T-248: Near Real-Time Analysis of Radiation Delivery and Imaging, Accuracy to Ensure Patient Safety

    SciTech Connect

    Wijesooriya, K; Seitter, K; Desai, V; Read, P; Larner, J

    2014-06-01

    Purpose: To develop and optimize an effective software method for comparing planned to delivered control point machine parameters for all VARIAN TrueBeam treatments so as to permit (1) assessment of a large patient pool throughout their treatment course to quantify treatment technique specific systematic and random uncertainty of observables, (2) quantify the site specific daily imaging shifts required for target alignment, and (3) define tolerance levels for mechanical parameters and imaging parameters based on statistical analysis data gathered, and the dosimetric impact of variations. Methods: Treatment and imaging log files were directly compared to plan parameters for Eclipse and Pinnacle planned treatments via 3D, IMRT, control point, RapidArc, and electrons. Each control point from all beams/arcs (7984) for all fractions (1940) of all patients treated over six months were analyzed. At each control point gantry angle, collimator angle, couch angle, jaw positions, MLC positions, MU were compared. Additionally per-treatment isocenter shifts were calculated. Results were analyzed as a whole in treatment type subsets: IMRT, 3D, RapidArc; and in treatment site subsets: brain, chest/mediastinum, esophagus, H and N, lung, pelvis, prostate. Results: Daily imaging isocenter shifts from initial external tattoo alignment were dependent on the treatment site with < 0.5 cm translational shifts for H and N, Brain, and lung SBRT, while pelvis, esophagus shifts were ∼1 cm. Mechanical delivery parameters were within tolerance levels for all sub-beams. The largest variations were for RapidArc plans: gantry angle 0.11±0.12,collimator angle 0.00±0.00, jaw positions 0.48±0.26, MLC leaf positions 0.66±0.08, MU 0.14±0.34. Conclusion: Per-control point validation reveals deviations between planned and delivered parameters. If used in a near real-time error checking system, patient safety can be improved by equipping the treatment delivery system with additional forcing

  17. Accuracy of dynamic patient surface monitoring using a time-of-flight camera and B-spline modeling for respiratory motion characterization.

    PubMed

    Wentz, T; Fayad, H; Bert, J; Pradier, O; Clement, J F; Vourch, S; Boussion, N; Visvikis, D

    2012-07-07

    Time-of-flight (ToF) camera technology provides a real-time depth map of a scene with adequate frequency for the monitoring of physiological patient motion. However, dynamic surface motion estimation using a ToF camera is limited by issues such as the raw measurement accuracy and the absence of fixed anatomical landmarks. In this work we propose to overcome these limitations using surface modeling through B-splines. This approach was assessed in terms of both motion estimation accuracy and associated variability improvements using acquisitions of an anthropomorphic surface phantom for a range of observation distances (0.6-1.4 m). In addition, feasibility was demonstrated on patient acquisitions. Using the proposed B-spline modeling, the mean motion estimation error and associated repeatability with respect to the raw measurements decreased by a factor of 3. Significant correlation was found between patients' surfaces motion extracted using the proposed B-spline approach applied to the ToF data and the one extracted from synchronized 4D-CT acquisitions as the ground truth. ToF cameras represent a promising alternative for contact-less patient surface monitoring for respiratory motion synchronization or modeling in imaging and/or radiotherapy applications.

  18. Time domain responses of a prestressed beam and prestress identification

    NASA Astrophysics Data System (ADS)

    Law, S. S.; Lu, Z. R.

    2005-12-01

    The time-domain response of a prestressed Euler-Bernoulli beam under external excitation is studied based on modal superposition. The prestress force is then identified in the time domain by a system identification approach and Tikhonov regularization technique is used to provide bounds to the ill-conditioned results in the identified problem. Both measured displacements and strains are used. The noise effect is improved using the orthogonal polynomial function, and cases with either sinusoidal or impulsive excitations are illustrated to give very good results from the lower three measured modes and data obtained from three measurement points. Work in this paper demonstrates the feasibility of indirectly identifying the prestress force in a beam.

  19. Location cuing and response time distributions in visual attention.

    PubMed

    Gottlob, Lawrence R

    2004-11-01

    The allocation of visual attention was investigated in two experiments. In Experiment 1 (n = 24), a peripheral cue was presented, and in Experiment 2 (n = 24), a central cue was used. In both experiments, cue validity was 90%, and the task was four-choice target identification. Response time distributions were collected for valid trials over five cue-target stimulus onset asynchronies (SOAs), and ex-Gaussian parameters were extracted. In both experiments, only the mean of the Gaussian component decreased as a function of cue-target SOA, which implied a strict time axis translation of the distributions. The results were consistent with sequential sampling models featuring a variable delay in the onset of information uptake.

  20. Fast-Response-Time Shape-Memory-Effect Foam Actuators

    NASA Technical Reports Server (NTRS)

    Jardine, Peter

    2010-01-01

    Bulk shape memory alloys, such as Nitinol or CuAlZn, display strong recovery forces undergoing a phase transformation after being strained in their martensitic state. These recovery forces are used for actuation. As the phase transformation is thermally driven, the response time of the actuation can be slow, as the heat must be passively inserted or removed from the alloy. Shape memory alloy TiNi torque tubes have been investigated for at least 20 years and have demonstrated high actuation forces [3,000 in.-lb (approximately equal to 340 N-m) torques] and are very lightweight. However, they are not easy to attach to existing structures. Adhesives will fail in shear at low-torque loads and the TiNi is not weldable, so that mechanical crimp fits have been generally used. These are not reliable, especially in vibratory environments. The TiNi is also slow to heat up, as it can only be heated indirectly using heater and cooling must be done passively. This has restricted their use to on-off actuators where cycle times of approximately one minute is acceptable. Self-propagating high-temperature synthesis (SHS) has been used in the past to make porous TiNi metal foams. Shape Change Technologies has been able to train SHS derived TiNi to exhibit the shape memory effect. As it is an open-celled material, fast response times were observed when the material was heated using hot and cold fluids. A methodology was developed to make the open-celled porous TiNi foams as a tube with integrated hexagonal ends, which then becomes a torsional actuator with fast response times. Under processing developed independently, researchers were able to verify torques of 84 in.-lb (approximately equal to 9.5 Nm) using an actuator weighing 1.3 oz (approximately equal to 37 g) with very fast (less than 1/16th of a second) initial response times when hot and cold fluids were used to facilitate heat transfer. Integrated structural connections were added as part of the net shape process, eliminating

  1. Time domain responses of hydraulic bushing with two flow passages

    NASA Astrophysics Data System (ADS)

    Chai, Tan; Dreyer, Jason T.; Singh, Rajendra

    2014-02-01

    Hydraulic bushings are commonly employed in vehicle suspension and body sub-frame systems to control motion, vibration, and structure-borne noise. Since literature on this topic is sparse, a controlled bushing prototype which accommodates a combination of long and short flow passages and flow restriction elements is first designed, constructed and instrumented. Step-up and step-down responses of several typical fluid-filled bushing configurations are measured along with steady harmonic time histories of transmitted force and internal pressures. To analyze the experimental results and gain physical insights into the hydraulic bushing system, lumped system models of bushings with different design features are developed, and analytical expressions of transmitted force and internal pressure responses are derived by using the convolution method. Parametric studies are also conducted to examine the effect of hydraulic element parameters. System parameters are successfully estimated for both harmonic and step responses using theory and measurements, and the dynamic force measurements are analyzed using analytical predictions. Finally, some nonlinearities of the system are also observed, and the fluid resistance of flow passage is found to be the most nonlinear element.

  2. High-accuracy photoreceiver frequency response measurements at 1.55 µm by use of a heterodyne phase-locked loop.

    PubMed

    Dennis, Tasshi; Hale, Paul D

    2011-10-10

    We demonstrate a high-accuracy heterodyne measurement system for characterizing the magnitude of the frequency response of high-speed 1.55 µm photoreceivers from 2 MHz to greater than 50 GHz. At measurement frequencies below 2 GHz, we employ a phase-locked loop with a double-heterodyne detection scheme, which enables precise tuning of the heterodyne beat frequency with an RF synthesizer. At frequencies above 2 GHz the system is operated in free-run mode with thermal tuning of the laser beat frequency. We estimate the measurement uncertainties for the low frequency range and compare the measured high-frequency response of a photoreceiver to a measurement using electro-optic sampling.

  3. Ampoule failure sensor time response testing: Experiment 1

    NASA Technical Reports Server (NTRS)

    Johnson, M. L.; Watring, D. A.

    1994-01-01

    The response time of an ampoule failure sensor exposed to a liquid or vapor gallium-arsenide (GaAs) is investigated. The experimental configuration represents the sample/ampoule cartridge assembly used in NASA's Crystal Growth Furnace (CGF). The sensor is a chemical fuse made from a metal with which the semiconductor material reacts more rapidly than it does with the containing cartridge. For the III-IV compound of GaAs, a platinum metal was chosen based on the reaction of platinum and arsenic at elevated temperatures which forms a low melting eutectic. Ampoule failure is indicated by a step change in resistance of the failure sensor on the order of megohms. The sensors will increase the safety of crystal growth experiments by providing an indication that an ampoule has failed. Experimental results indicate that the response times (after a known ampoule failure) for the 0.003 and 0.010 inch ampoule failure sensors are 2.4 and 3.6 minutes, respectively. This ampoule failure sensor will be utilized in the CGF during the second United States Microgravity Laboratory Mission (USML-2) and is the subject of a NASA patent application.

  4. Effect of defence response time during lunge in foil fencing.

    PubMed

    Gutiérrez-Cruz, Carmen; Rojas, F Javier; Gutiérrez-Davila, Marcos

    2016-01-01

    The aim of this study was to analyse the effect of stimulus change timing on reaction response time parameters, horizontal velocity of the centre of mass (CM) and precision during offensive actions in fencing. Twelve fencers from the Spanish National Foil Team were included in the study. Two 500 Hz force plates were used to register the horizontal component of the reaction force while a 3D video camera set at 250 Hz recorded the spatial position of 11 body markers and a projector connected to a programmed stopwatch projected a moving target (stimulus) on a screen. When the circle (target) appeared in the centre of the plastron, fencers had to execute a step-forward-lunge as fast as possible, trying to touch the circle with the tip of the foil. During the lunge, the position of the target could randomly shift or not to three different positions. The stimulus change was performed randomly at four different times with a progressive delay. The results show that target changes did not have any effect when they occurred at the beginning of the movement sequence. However, when the target change was delayed, reaction and movement times increased and the technical execution of the lunge changed, leading to more errors.

  5. Spectral responsivity calibration of the reference radiation thermometer at KRISS by using a super-continuum laser-based high-accuracy monochromatic source

    NASA Astrophysics Data System (ADS)

    Yoo, Yong Shim; Kim, Gun Jung; Park, Seongchong; Lee, Dong-Hoon; Kim, Bong-Hak

    2016-12-01

    We report on the calibration of the relative spectral responsivity of the reference radiation thermometer, model LP4, which is used for the experimental realisation of the international temperature scale of 1990 above 960 °C at the Korea Research Institute of Standards and Science. The relative spectral responsivity of LP4 is measured by using a monochromatic source consisting of a super-continuum laser and a double-grating monochromator. By monitoring the wavelength of the output beam directly with a calibrated wavelength-meter, we achieved a high-accuracy measurement of spectral responsivity with a maximum wavelength error of less than 3 pm, a narrow spectral bandwidth of less than 0.4 nm, and a high dynamic range over 8 decades. We evaluated the contributions of various uncertainty components of the spectral responsivity measurement to the uncertainty of the temperature scale based on a practical estimation approach, which numerically calculates the maximal effects of the variations of each component. As a result, we evaluate the uncertainty contribution from the spectral responsivity measurement to the temperature scale to be less than 64 mK (k  =  1) in a range from 660 °C to 2749 °C for the LP4 with a filter at 650 nm.

  6. Diagnostic Accuracy of Hepatic Vein Arrival Time Performed with Contrast-Enhanced Ultrasonography for Cirrhosis: A Systematic Review and Meta-Analysis

    PubMed Central

    Kim, Gaeun; Shim, Kwang Yong; Baik, Soon Koo

    2017-01-01

    Background/Aims We identified reports in the literature regarding the diagnostic accuracy of hepatic vein arrival time (HVAT) measured by contrast-enhanced ultrasonography (CEUS) to assess hepatic fibrosis in cirrhosis. Methods The Ovid MEDLINE, Embase, and Cochrane databases were searched for all studies published up to 23 July 2015 that evaluated liver status using CEUS and liver biopsy (LB). The QUADAS-II (quality assessment of diagnostic accuracy studies-II) was applied to assess the internal validity of the diagnostic studies. Selected studies were subjected to a meta-analysis with MetaDisc 1.4 and RevMan 5.3. Results A total of 12 studies including 844 patients with chronic liver disease met our inclusion criteria. The overall summary sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio of the HVAT measured by CEUS for the detection of cirrhosis compared to LB were 0.83 (95% confidence interval [CI], 0.77 to 0.89), 0.75 (95% CI, 0.69 to 0.79), 3.45 (95% CI, 1.60 to 7.43), and 0.28 (95% CI, 0.10 to 0.74), respectively. The summary diagnostic odds ratio (random effects model) was 15.23 (95% CI, 3.07 to 75.47), the summary receiver operator characteristics area under the curve was 0.74 (standard error [SE]=0.14), and the index Q was 0.69 (SE=0.11). Conclusions Based on a systematic review, the measurement of HVAT by CEUS exhibited an increased accuracy and correlation for the detection of cirrhosis. PMID:27538445

  7. Targeting Accuracy, Procedure Times and User Experience of 240 Experimental MRI Biopsies Guided by a Clinical Add-On Navigation System

    PubMed Central

    Busse, Harald; Riedel, Tim; Garnov, Nikita; Thörmer, Gregor; Kahn, Thomas; Moche, Michael

    2015-01-01

    Objectives MRI is of great clinical utility for the guidance of special diagnostic and therapeutic interventions. The majority of such procedures are performed iteratively ("in-and-out") in standard, closed-bore MRI systems with control imaging inside the bore and needle adjustments outside the bore. The fundamental limitations of such an approach have led to the development of various assistance techniques, from simple guidance tools to advanced navigation systems. The purpose of this work was to thoroughly assess the targeting accuracy, workflow and usability of a clinical add-on navigation solution on 240 simulated biopsies by different medical operators. Methods Navigation relied on a virtual 3D MRI scene with real-time overlay of the optically tracked biopsy needle. Smart reference markers on a freely adjustable arm ensured proper registration. Twenty-four operators – attending (AR) and resident radiologists (RR) as well as medical students (MS) – performed well-controlled biopsies of 10 embedded model targets (mean diameter: 8.5 mm, insertion depths: 17-76 mm). Targeting accuracy, procedure times and 13 Likert scores on system performance were determined (strong agreement: 5.0). Results Differences in diagnostic success rates (AR: 93%, RR: 88%, MS: 81%) were not significant. In contrast, between-group differences in biopsy times (AR: 4:15, RR: 4:40, MS: 5:06 min:sec) differed significantly (p<0.01). Mean overall rating was 4.2. The average operator would use the system again (4.8) and stated that the outcome justifies the extra effort (4.4). Lowest agreement was reported for the robustness against external perturbations (2.8). Conclusions The described combination of optical tracking technology with an automatic MRI registration appears to be sufficiently accurate for instrument guidance in a standard (closed-bore) MRI environment. High targeting accuracy and usability was demonstrated on a relatively large number of procedures and operators. Between

  8. Role of Estrogen Response Element in the Human Prolactin Gene: Transcriptional Response and Timing.

    PubMed

    McNamara, Anne V; Adamson, Antony D; Dunham, Lee S S; Semprini, Sabrina; Spiller, David G; McNeilly, Alan S; Mullins, John J; Davis, Julian R E; White, Michael R H

    2016-02-01

    The use of bacterial artificial chromosome (BAC) reporter constructs in molecular physiology enables the inclusion of large sections of flanking DNA, likely to contain regulatory elements and enhancers regions that contribute to the transcriptional output of a gene. Using BAC recombineering, we have manipulated a 160-kb human prolactin luciferase (hPRL-Luc) BAC construct and mutated the previously defined proximal estrogen response element (ERE) located -1189 bp relative to the transcription start site, to assess its involvement in the estrogen responsiveness of the entire hPRL locus. We found that GH3 cell lines stably expressing Luc under control of the ERE-mutated hPRL promoter (ERE-Mut) displayed a dramatically reduced transcriptional response to 17β-estradiol (E2) treatment compared with cells expressing Luc from the wild-type (WT) ERE hPRL-Luc promoter (ERE-WT). The -1189 ERE controls not only the response to E2 treatment but also the acute transcriptional response to TNFα, which was abolished in ERE-Mut cells. ERE-WT cells displayed a biphasic transcriptional response after TNFα treatment, the acute phase of which was blocked after treatment with the estrogen receptor antagonist 4-hydroxy-tamoxifen. Unexpectedly, we show the oscillatory characteristics of hPRL promoter activity in individual living cells were unaffected by disruption of this crucial response element, real-time bioluminescence imaging showed that transcription cycles were maintained, with similar cycle lengths, in ERE-WT and ERE-Mut cells. These data suggest the -1189 ERE is the dominant response element involved in the hPRL transcriptional response to both E2 and TNFα and, crucially, that cycles of hPRL promoter activity are independent of estrogen receptor binding.

  9. Characteristics and control response of the TOPAZ II Reactor System Real-time Dynamic Simulator

    SciTech Connect

    Kwok, K.S.

    1993-11-12

    A dynamic simulator of the TOPAZ II reactor system has been developed for the Nuclear Electric Propulsion Space Test Program. The simulator combines first-principle modeling and empirical correlations in its algorithm to attain the modeling accuracy and computational through-put that are required for real-time execution. The overall execution time of the simulator for each time step is 15 ms when no data is written to the disk, and 18 ms when nine double precision data points are written to the disk once in every time step. The simulation program has been tested and it is able to handle a step decrease of $8 worth of reactivity. It also provides simulations of fuel, emitter, collector, stainless steel, and ZrH moderator failures. Presented in this paper are the models used in the calculations, a sample simulation session, and a discussion of the performance and limitations of the simulator. The simulator has been found to provide realistic real-time dynamic response of the TOPAZ II reactor system under both normal and casualty conditions.

  10. Assessment of visual quality and spatial accuracy of fast anisotropic diffusion and scan conversion algorithms for real-time three-dimensional spherical ultrasound

    NASA Astrophysics Data System (ADS)

    Duan, Qi; Angelini, Elsa D.; Laine, Andrew

    2004-04-01

    Three-dimensional ultrasound machines based on matrix phased-array transducers are gaining predominance for real-time dynamic screening in cardiac and obstetric practice. These transducers array acquire three-dimensional data in spherical coordinates along lines tiled in azimuth and elevation angles at incremental depth. This study aims at evaluating fast filtering and scan conversion algorithms applied in the spherical domain prior to visualization into Cartesian coordinates for visual quality and spatial measurement accuracy. Fast 3d scan conversion algorithms were implemented and with different order interpolation kernels. Downsizing and smoothing of sampling artifacts were integrated in the scan conversion process. In addition, a denoising scheme for spherical coordinate data with 3d anisotropic diffusion was implemented and applied prior to scan conversion to improve image quality. Reconstruction results under different parameter settings, such as different interpolation kernels, scaling factor, smoothing options, and denoising, are reported. Image quality was evaluated on several data sets via visual inspections and measurements of cylinder objects dimensions. Error measurements of the cylinder's radius, reported in this paper, show that the proposed fast scan conversion algorithm can correctly reconstruct three-dimensional ultrasound in Cartesian coordinates under tuned parameter settings. Denoising via three-dimensional anisotropic diffusion was able to greatly improve the quality of resampled data without affecting the accuracy of spatial information after the modification of the introduction of a variable gradient threshold parameter.

  11. Study on desirable ionospheric corrections accuracy for network-RTK positioning and its impact on time-to-fix and probability of successful single-epoch ambiguity resolution

    NASA Astrophysics Data System (ADS)

    Paziewski, Jacek

    2016-02-01

    The mitigation of ionospheric delay is still of crucial interest in GNSS positioning, especially in precise solutions such as instantaneous RTK positioning. Thus, several effective algorithms and functional models were developed, and also numerous investigations of ionospheric correction properties in RTK positioning have been performed so far. One of the most highly effective approaches in precise relative positioning is the application of the ionosphere-weighted model with network-derived corrections. This contribution investigates the impact of the accuracy of the network ionospheric corrections on time-to-fix in RTK-OTF positioning. Also, an attempt has been made to estimate the desirable accuracy of the network ionospheric corrections, allowing for reliable instantaneous ambiguity resolution. The experiment is based on a multi-baseline GPS RTK positioning supported with network-derived ionospheric corrections for medium length baselines. The results show that in such scenario, the double-differenced ionospheric correction residuals should not exceed ∼1/3 of the L1 wavelength for successful single-epoch ambiguity resolution.

  12. Time-varying boundaries for diffusion models of decision making and response time

    PubMed Central

    Zhang, Shunan; Lee, Michael D.; Vandekerckhove, Joachim; Maris, Gunter; Wagenmakers, Eric-Jan

    2014-01-01

    Diffusion models are widely-used and successful accounts of the time course of two-choice decision making. Most diffusion models assume constant boundaries, which are the threshold levels of evidence that must be sampled from a stimulus to reach a decision. We summarize theoretical results from statistics that relate distributions of decisions and response times to diffusion models with time-varying boundaries. We then develop a computational method for finding time-varying boundaries from empirical data, and apply our new method to two problems. The first problem involves finding the time-varying boundaries that make diffusion models equivalent to the alternative sequential sampling class of accumulator models. The second problem involves finding the time-varying boundaries, at the individual level, that best fit empirical data for perceptual stimuli that provide equal evidence for both decision alternatives. We discuss the theoretical and modeling implications of using time-varying boundaries in diffusion models, as well as the limitations and potential of our approach to their inference. PMID:25538642

  13. Bayesian and maximum likelihood estimation of hierarchical response time models

    PubMed Central

    Farrell, Simon; Ludwig, Casimir

    2008-01-01

    Hierarchical (or multilevel) statistical models have become increasingly popular in psychology in the last few years. We consider the application of multilevel modeling to the ex-Gaussian, a popular model of response times. Single-level estimation is compared with hierarchical estimation of parameters of the ex-Gaussian distribution. Additionally, for each approach maximum likelihood (ML) estimation is compared with Bayesian estimation. A set of simulations and analyses of parameter recovery show that although all methods perform adequately well, hierarchical methods are better able to recover the parameters of the ex-Gaussian by reducing the variability in recovered parameters. At each level, little overall difference was observed between the ML and Bayesian methods. PMID:19001592

  14. Word Association in L1 and L2: An Exploratory Study of Response Types, Response Times, and Interlingual Mediation

    ERIC Educational Resources Information Center

    Fitzpatrick, Tess; Izura, Cristina

    2011-01-01

    Word association responses in first-language (L1) Spanish and second-language (L2) English were investigated by means of response latencies and types of associative response produced. The primary aims were to establish whether (a) some response types are produced more often or faster than others, (b) participants' L2 response time profiles mirror…

  15. GPS computer navigators to shorten EMS response and transport times.

    PubMed

    Ota, F S; Muramatsu, R S; Yoshida, B H; Yamamoto, L G

    2001-05-01

    GPS (global positioning satellite system to determine one's position on earth) units have become inexpensive and compact. The purpose of this study is to assess the effectiveness of a GPS enhanced computer street map navigator to improve the ability of EMS drivers in an urban setting to locate their destination and shorten response times. For part I, residential addresses in the city were randomly selected from a telephone directory. Two driver/navigator teams were assigned to drive to the address adhering to speed limits. One team used a standard street map, whereas the other team used a GPS computer navigator. The travel time and distance of the runs were compared. For part II, the computer GPS navigator was placed on an ambulance to supplement their normal methods of navigation to find the address requesting EMS. After the run was completed, EMS providers were interviewed to determine their opinion of whether the GPS navigator was helpful. For part I the results showed that in the 29 initial test runs, comparing the GPS team versus the standard map team, the mean distances traveled were 8.7 versus 9.0 kilometers (not significant) and the mean travel times were 13.5 versus 14.6 minutes (P=.02), respectively. The GPS team arrived faster in 72% runs. For part II the results showed that most EMS providers surveyed noted that the GPS computer navigator enhanced their ability to find the destination and all EMS providers acknowledged that it would enhance their ability to find a destination in an area in which they were unfamiliar. These results suggest that a portable GPS computer navigator system is helpful and can enhance the ability of prehospital care providers to locate their destination. Because these units are accurate and inexpensive, GPS computer navigators may be a valuable tool in reducing pre-hospital transport times.

  16. [Accuracy of a real-time polymerase-chain-reaction assay for a quantitative estimation of genetically modified sources in food products].

    PubMed

    Abramov, D D; Trofimov, D Iu; Rebrikov, D V

    2006-01-01

    The accuracy of a real-time polymerase-chain-reaction assay for genetically modified sources in food products was determined using two official test systems (kits) of primers and samples. These kits were recommended by the Federal Center of State Sanitary and Epidemiological Surveillance (Russian Ministry of Health) and the European Commission. We used the following three models of thermocyclers: iCycler iQ (BioRad, United States), Rotor-Gene 3000 (Corbett Research, Australia), and DT-322 (DNA-Technology, Russia). Studies of samples that contained 1% genetically modified sources showed that the error of a quantitative assay for genetically modified sources in food products corresponds to 20-30% and does not depend on the kit type and the thermocycler model used.

  17. Response time satisfaction in a real-time knowledge-based system

    SciTech Connect

    Frank, D. ); Friesen, D.; Williams, G. . Dept. of Computer Science)

    1990-08-01

    Response to interrupts within a certain time frame is an important issue for all software operating in real-time environment. A knowledge-based system (KBS) is no exception. Prior work on real-time knowledge-based systems either concentrated on improving the performance of the KBS in order to meet these constraints or focused on producing a better solution as more time was allowed. However, a problem with much of the latter research was that it required inference-time costs to be hardcoded into the different branches of reasoning. This limited the type of reasoning possible and the size of the KBS. Furthermore, performing the analysis required to derive those numbers is very difficult in knowledge based systems. This research explored a model for overcoming these drawbacks. It is based on integrating conventional programming techniques used to control task processing with knowledge-based techniques used to actually produce task results. The C-Language Integrated Production System (CLIPS) was used for the inference engine in the KBS; using CLIPS for the inference engine simplified the rapid context switching required. Thus, the KBS could respond in a timely manner while maintaining the fullest spectrum of KBS functionality.

  18. The accuracy of the first response histidine-rich protein2 rapid diagnostic test compared with malaria microscopy for guiding field treatment in an outbreak of falciparum malaria

    PubMed Central

    Ghouth, Abdulla Salim Bin; Nasseb, Faraj Mubarak; Al-Kaldy, Khaled Hussin

    2012-01-01

    Background: Recent WHO guidelines recommended a universal “test and treat” strategy for malaria mainly by use of the rapid diagnostic test (RDT) in all areas. There are concerns about RDT that use the antigen histidine-rich protein2 (HRP2) to detect Plasmodium falciparum, because infection can persist after effective treatment. Aim: The aim of this paper is to describe the accuracy of the first response (HRP2)-RDT compared with malaria microscopy used for guiding the field treatment of patients in an outbreak situation in the Al-Rahabah area in Al-Rydah district in Hadramout/Yemen. Materials and Methods: An ad hoc cross sectional survey of all febrile patients in the affected area was conducted in May 2011. The field team was developed including the case management group and the entomology group. The group of case management prepared their plan based on “test and treat” strategy by using First Response Malaria Antigen HRP2 rapid diagnostic test for falciparum malaria, artemsinin-based combination therapy (ACT) according to the national policy of anti-malaria drugs in Yemen were supplied to treat those who were found to be RDT positive in the field; also blood smear films were taken from every patient with fever in order to validate the use of the RDT in the field. Blood film slides prepared and read by skilled lab technicians, the fourth reading was done by one lab expert in the malaria referral lab. Results: The accuracy parameters of HRP2 compared with microscopy are: Sensitivity (74%), specificity (94%). The positive predictive value is 68% and the negative predictive value is 96%. Total agreement is 148/162 (93%) and the overall prevalence is 14%. All the positive malaria cases were of P. falciparum either coming from RDT or microscopy. Conclusions: HRP2–rapid test is an acceptable test as a guide for field treatment in an outbreak situation where prompt response is indicated. Good prepared blood film slides should be used as it is feasible to

  19. Accuracy of erythrogram and serum ferritin for the maternal anemia diagnosis (AMA): a phase 3 diagnostic study on prediction of the therapeutic responsiveness to oral iron in pregnancy

    PubMed Central

    2013-01-01

    Background Pregnancy anemia remains as a public health problem, since the official reports in the 70’s. To guide the treatment of iron-deficiency anemia in pregnancy, the haemoglobin concentration is the most used test in spite of its low accuracy, and serum ferritin is the most reliable test, although its cutoff point remains an issue. Methods/design The aim of this protocol is to verify the accuracy of erythrocyte indices and serum ferritin (studied tests) for the diagnosis of functional iron-deficiency in pregnancy using the iron-therapy responsiveness as the gold-standard. This is an ongoing phase III accuracy study initiated in August 2011 and to be concluded in April 2013. The subjects are anemic pregnant women (haemoglobin concentration < 11.0 g/dL) attended at a low-risk prenatal care center in the Northeast of Brazil. The sample size (n 278) was calculated to estimate sensitivity of 90% and 80% of specificity with relative error of 10% and power of 95%. This study has a prospective design with a before-after intervention of 80 mg of daily oral iron during 90 days and will be analyzed as a delayed-type cross-sectional study. Women at the second trimester of pregnancy are being evaluated with clinical and laboratorial examinations at the enrollment and monthly. The ‘responsiveness to therapeutic test with oral iron’ (gold-standard) was defined to an increase of at least 0.55 Z-score in haemoglobin after 4 weeks of treatment and a total dose of 1200 mg of iron. At the study conclusion, sensitivities, specificities, predictive values, likelihood ratios and areas under the ROC (Receiver Operating Characteristic) curves of serum ferritin and erythrocyte indices (red blood cell count, haematocrit, haemoglobin concentration, mean corpuscular volume, mean corpuscular haemoglobin, mean corpuscular haemoglobin concentration, red blood cell distribution width, reticulocyte count) will be tested. The compliance and adverse effects are considered

  20. Response time, visual search strategy, and anticipatory skills in volleyball players.

    PubMed

    Piras, Alessandro; Lobietti, Roberto; Squatrito, Salvatore

    2014-01-01

    This paper aimed at comparing expert and novice volleyball players in a visuomotor task using realistic stimuli. Videos of a volleyball setter performing offensive action were presented to participants, while their eye movements were recorded by a head-mounted video based eye tracker. Participants were asked to foresee the direction (forward or backward) of the setter's toss by pressing one of two keys. Key-press response time, response accuracy, and gaze behaviour were measured from the first frame showing the setter's hand-ball contact to the button pressed by the participants. Experts were faster and more accurate in predicting the direction of the setting than novices, showing accurate predictions when they used a search strategy involving fewer fixations of longer duration, as well as spending less time in fixating all display areas from which they extract critical information for the judgment. These results are consistent with the view that superior performance in experts is due to their ability to efficiently encode domain-specific information that is relevant to the task.

  1. Response Time, Visual Search Strategy, and Anticipatory Skills in Volleyball Players

    PubMed Central

    Lobietti, Roberto

    2014-01-01

    This paper aimed at comparing expert and novice volleyball players in a visuomotor task using realistic stimuli. Videos of a volleyball setter performing offensive action were presented to participants, while their eye movements were recorded by a head-mounted video based eye tracker. Participants were asked to foresee the direction (forward or backward) of the setter's toss by pressing one of two keys. Key-press response time, response accuracy, and gaze behaviour were measured from the first frame showing the setter's hand-ball contact to the button pressed by the participants. Experts were faster and more accurate in predicting the direction of the setting than novices, showing accurate predictions when they used a search strategy involving fewer fixations of longer duration, as well as spending less time in fixating all display areas from which they extract critical information for the judgment. These results are consistent with the view that superior performance in experts is due to their ability to efficiently encode domain-specific information that is relevant to the task. PMID:24876946

  2. Linear control of neuronal spike timing using phase response curves.

    PubMed

    Stigen, Tyler; Danzl, Per; Moehlis, Jeff; Netoff, Theoden

    2009-01-01

    We propose a simple, robust, linear method to control the spike timing of a periodically firing neuron. The control scheme uses the neuron's phase response curve to identify an area of optimal sensitivity for the chosen stimulation parameters. The spike advance as a function of current pulse amplitude is characterized at the optimal phase and a linear least-squares regression is fit to the data. The inverted regression is used as the control function for this method. The efficacy of this method is demonstrated through numerical simulations of a Hodgkin-Huxley style neuron model as well as in real neurons from rat hippocampal slice preparations. The study shows a proof of concept for the application of a linear control scheme to control neuron spike timing in-vitro. This study was done on an individual cell level, but translation to a tissue or network level is possible. Control schemes of this type could be implemented in a closed loop implantable device to treat neuromotor disorders involving pathologically neuronal activity such as epilepsy or Parkinson's disease.

  3. Heat-Treatment-Responsive Proteins in Different Developmental Stages of Tomato Pollen Detected by Targeted Mass Accuracy Precursor Alignment (tMAPA).

    PubMed

    Chaturvedi, Palak; Doerfler, Hannes; Jegadeesan, Sridharan; Ghatak, Arindam; Pressman, Etan; Castillejo, Maria Angeles; Wienkoop, Stefanie; Egelhofer, Volker; Firon, Nurit; Weckwerth, Wolfram

    2015-11-06

    Recently, we have developed a quantitative shotgun proteomics strategy called mass accuracy precursor alignment (MAPA). The MAPA algorithm uses high mass accuracy to bin mass-to-charge (m/z) ratios of precursor ions from LC-MS analyses, determines their intensities, and extracts a quantitative sample versus m/z ratio data alignment matrix from a multitude of samples. Here, we introduce a novel feature of this algorithm that allows the extraction and alignment of proteotypic peptide precursor ions or any other target peptide from complex shotgun proteomics data for accurate quantification of unique proteins. This strategy circumvents the problem of confusing the quantification of proteins due to indistinguishable protein isoforms by a typical shotgun proteomics approach. We applied this strategy to a comparison of control and heat-treated tomato pollen grains at two developmental stages, post-meiotic and mature. Pollen is a temperature-sensitive tissue involved in the reproductive cycle of plants and plays a major role in fruit setting and yield. By LC-MS-based shotgun proteomics, we identified more than 2000 proteins in total for all different tissues. By applying the targeted MAPA data-processing strategy, 51 unique proteins were identified as heat-treatment-responsive protein candidates. The potential function of the identified candidates in a specific developmental stage is discussed.

  4. Prairie forb response to timing of vole herbivory.

    PubMed

    Sullivan, Amy T; Howe, Henry F

    2009-05-01

    The timing of herbivory can be an important factor in the strength and direction of plant response to herbivore damage. To determine the effect of vole herbivory timing within a growing season on tallgrass prairie forbs, we used individual plant enclosures to limit vole access to three species, Desmanthus illinoensis, Echinacea purpurea, and Heliopsis helianthoides, in an experimental restoration in northern Illinois, USA. As part of a long-term experiment, we implemented five vole access treatments in 2003: (1) vole access for the entire growing season, (2) early-season access, (3) mid-season access, (4) late-season access, and (5) no vole access. We protected all plants from herbivory in the following growing season (2004) to test whether the effects of herbivory in one growing season carried over to the next. We also tested how restoration planting design, including seeding time (June or December) and density (35 or 350 seeds/m2 of each species) affected patterns of herbivory and plant recovery. Vole access for the entire growing season was most detrimental for the growth and reproduction of all three species. In contrast, vole access for a portion of the growing season had different effects on the three species: Desmanthus growth and reproduction was negatively affected by early-season access, Echinacea reproductive output was reduced by late-season access, and Heliopsis was not affected by early-, mid-, or late-season vole access. Negative effects of continual vole access carried over to the following growing season for Desmanthus and Heliopsis, but not for Echinacea. Effects of herbivory did not carry over to the next season for Echinacea and Heliopsis when plants were accessible to voles for only part of the growing season. In contrast, Desmanthus plants exposed to early-season herbivory in one year continued to produce fewer seeds per plant after being protected from vole herbivory for a growing season. Planting density and planting season had mixed effects

  5. Control of response timing occurs during the simple reaction time interval but on-line for choice reaction time.

    PubMed

    Maslovat, Dana; Klapp, Stuart T; Jagacinski, Richard J; Franks, Ian M

    2014-10-01

    The preparation of multiple element movements has been examined for decades, with no clear explanation offered for the disparate results observed. Results from 2 experiments are presented and, in conjunction with previous results, a theoretical interpretation is offered regarding the preparatory processes that occur before, during and after the reaction time (RT) interval for multiple element movements during both simple and choice RT paradigms. In Experiment 1, number of elements and timing complexity were manipulated in a simple RT key-press task, using a startling acoustic stimulus to probe advance preparation. Both startle and nonstartle RT increased with number of movement elements and for a movement with increased timing complexity, providing evidence that the control of response timing occurs during the RT interval. In Experiment 2, the production of key-press movements of varying number of elements was compared in a simple versus choice RT paradigm. Results indicated that simple RT was affected by the number of elements, yet choice RT was not. Additionally, choice RT trials showed significantly longer interresponse intervals compared with those observed in simple RT trials, providing evidence for online processing in choice RT. The results of both studies, together with previous findings, suggest that planning of the timing of the onsets of the elements is prepared during simple RT, whereas planning of other aspects of the sequence of elements seems to occur in the foreperiod prior to the "go" signal. Conversely, in the choice RT paradigm, timing seems to be controlled online. This explanation may bring closure on difficulties encountered in over 50 years of research examining response preparation for complex movements.

  6. Time-resolved diagnostics for concrete target response

    SciTech Connect

    Baum, D.W.; Kuklo, R.M.; Reaugh, J.E.; Simonson, S.C.

    1996-05-01

    In order to facilitate the design of advanced penetrating weapons for defeating land targets, the interaction of concrete with high-velocity penetrators needs to be better characterized. To aid in this effort, three new types of time-resolved diagnostics are being developed and have been used in two experiments and one demonstration: fiber optic arrays to localize penetrators in space and time, Fabry-Perot velocimetry to record the concrete particle velocity, which is related to the pressure, at specific locations within concrete targets, and micropower impulse radar to provide a non-intrusive measure of the penetrator position-time history in a target. The two experiments used the fiber optic array and the Fabry-Perot velocimeter to diagnose the response of concrete to penetration by a Viper shaped charge jet. The results were analyzed using the CALE continuum mechanics simulation program, for which a preliminary model of the material properties of concrete was developed. The fiber optic arrays recorded the bow shock at locations 6.4 and 16.9 cm from the front surfaces. The Fabry-Perot velocimeter measured a free-surface velocity of 0.13 km/s at a distance of 3 cm and obliquity 70{degree} from the jet, which was moving at an interface velocity of 4.0 km/s at a depth of 29 cm. These values imply a pressure of about 6.6 kbar at that location. The demonstration used micropower impulse radar with a pulse repetition frequency of 0.25 MHz and a cell size of 30 ps to detect and record the motion of a metal penetrator simulant moving inside a cylindrical concrete target.

  7. Development of X-Y servo pneumatic-piezoelectric hybrid actuators for position control with high response, large stroke and nanometer accuracy.

    PubMed

    Chiang, Mao-Hsiung

    2010-01-01

    This study aims to develop a X-Y dual-axial intelligent servo pneumatic-piezoelectric hybrid actuator for position control with high response, large stroke (250 mm, 200 mm) and nanometer accuracy (20 nm). In each axis, the rodless pneumatic actuator serves to position in coarse stroke and the piezoelectric actuator compensates in fine stroke. Thus, the overall control systems of the single axis become a dual-input single-output (DISO) system. Although the rodless pneumatic actuator has relatively larger friction force, it has the advantage of mechanism for multi-axial development. Thus, the X-Y dual-axial positioning system is developed based on the servo pneumatic-piezoelectric hybrid actuator. In addition, the decoupling self-organizing fuzzy sliding mode control is developed as the intelligent control strategies. Finally, the proposed novel intelligent X-Y dual-axial servo pneumatic-piezoelectric hybrid actuators are implemented and verified experimentally.

  8. High accuracy OMEGA timekeeping

    NASA Technical Reports Server (NTRS)

    Imbier, E. A.

    1982-01-01

    The Smithsonian Astrophysical Observatory (SAO) operates a worldwide satellite tracking network which uses a combination of OMEGA as a frequency reference, dual timing channels, and portable clock comparisons to maintain accurate epoch time. Propagational charts from the U.S. Coast Guard OMEGA monitor program minimize diurnal and seasonal effects. Daily phase value publications of the U.S. Naval Observatory provide corrections to the field collected timing data to produce an averaged time line comprised of straight line segments called a time history file (station clock minus UTC). Depending upon clock location, reduced time data accuracies of between two and eight microseconds are typical.

  9. Children's Processing and Comprehension of Complex Sentences Containing Temporal Connectives: The Influence of Memory on the Time Course of Accurate Responses

    ERIC Educational Resources Information Center

    Blything, Liam P.; Cain, Kate

    2016-01-01

    In a touch-screen paradigm, we recorded 3- to 7-year-olds' (N = 108) accuracy and response times (RTs) to assess their comprehension of 2-clause sentences containing "before" and "after". Children were influenced by order: performance was most accurate when the presentation order of the 2 clauses matched the chronological order…

  10. The impact of aging on the spatial accuracy of quick corrective arm movements in response to sudden target displacement during reaching

    PubMed Central

    Kimura, Daisuke; Kadota, Koji; Kinoshita, Hiroshi

    2015-01-01

    Age-related declines in visuomotor processing speed can have a large impact on motor performance in elderly individuals. Contrary to previous findings, however, recent studies revealed that elderly individuals are able to quickly react to displacement of a visual target during reaching. Here, we investigated the influence of aging on quick, corrective responses to perturbations during reaching in the terms of their functional contribution to accuracy. Elderly and young adults performed reaching movements to a visual target that could be displaced during reaching, and they were requested to move their hand to reach the final target location as quickly as possible. Results showed that, for the younger group, the variance in the directional error of the corrective response correlated with the variance in the reaching trajectory at the halfway point of the reach, but the correlation decreased at the end of the reaching. On the other hand, such correlations were not significant in elderly participants, although the variance of the directional error did not show a significant difference between age groups. Thus, the quick, corrective response seems to play an important role in decreasing variability, especially before the end of reaching, and aging can impair this process. PMID:26441641

  11. Comparable performance of patients with obsessive-compulsive disorder (OCD) and healthy controls for verbal and nonverbal memory accuracy and confidence: time to forget the forgetfulness hypothesis of OCD?

    PubMed

    Moritz, Steffen; Kloss, Martin; von Eckstaedt, Francesca Vitzthum; Jelinek, Lena

    2009-04-30

    The memory deficit or forgetfulness hypothesis of obsessive-compulsive disorder (OCD) has received considerable attention and empirical effort over the past decades. The present study aimed to provide a fair test of its various formulations: (1) memory dysfunction in OCD is ubiquitous, that is, manifests irrespective of modality and material; (2) memory dysfunction is found for nonverbal but not verbal material, (3) memory dysfunction is secondary to executive impairment; and (4) memory dysfunction affects meta-memory rather than memory accuracy. Participants comprised 43 OCD patients and 46 healthy controls who were tested on the Picture Word Memory Test (PWMT), which provides several unconfounded parameters for nonverbal and verbal memory accuracy and confidence measures across different time-points. In addition, the Trail-Making Test B was administered to test assumption number 3. Replicating earlier work of our group, samples displayed similar performance on all indices. None of the different formulations of the memory deficit hypothesis were supported. In view of waning evidence for a global memory deficit in OCD, neuropsychological research on OCD should more thoroughly investigate moderators and triggers of occasional instances of impaired performance, particularly cognitive biases such as perfectionism and an inflated sense of responsibility.

  12. Interpreting response time effects in functional imaging studies

    PubMed Central

    Taylor, J.S.H.; Rastle, Kathleen; Davis, Matthew H.

    2014-01-01

    It has been suggested that differential neural activity in imaging studies is most informative if it is independent of response time (RT) differences. However, others view RT as a behavioural index of key cognitive processes, which is likely linked to underlying neural activity. Here, we reconcile these views using the effort and engagement framework developed by Taylor, Rastle, and Davis (2013) and data from the domain of reading aloud. We propose that differences in neural engagement should be independent of RT, whereas, differences in neural effort should co-vary with RT. We illustrate these different mechanisms using data from an fMRI study of neural activity during reading aloud of regular words, irregular words, and pseudowords. In line with our proposals, activation revealed by contrasts designed to tap differences in neural engagement (e.g., words are meaningful and therefore engage semantic representations more than pseudowords) survived correction for RT, whereas activation for contrasts designed to tap differences in neural effort (e.g., it is more difficult to generate the pronunciation of pseudowords than words) correlated with RT. However, even for contrasts designed to tap neural effort, activity remained after factoring out the RT–BOLD response correlation. This may reveal unpredicted differences in neural engagement (e.g., learning phonological forms for pseudowords > words) that could further the development of cognitive models of reading aloud. Our framework provides a theoretically well-grounded and easily implemented method for analysing and interpreting RT effects in neuroimaging studies of cognitive processes. PMID:24904992

  13. Reaction Time and Accuracy in Erroneous vs Correct Responses among Dyslexic and Regular Readers: From Letters to Sentences

    ERIC Educational Resources Information Center

    Horowitz-Kraus, Tzipi; Breznitz, Zvia

    2011-01-01

    Speed of processing (SOP) is a crucial factor in fluent reading and is measured using reading rate. This measure is commonly used to examine correct reading patterns, yet in the present study it is employed to determine whether differences in SOP exist for correct and incorrect reading. One of the characteristics of dyslexia is slow and inaccurate…

  14. The time domain response of some systems for sound reproduction

    NASA Astrophysics Data System (ADS)

    Nelson, P. A.; Rose, J. F. W.

    2006-09-01

    The perception in a listener of the existence of a "virtual" source of sound at a prescribed spatial position can be produced by ensuring that the acoustic signals at the listener's ears faithfully replicate those that would be produced by a "real" source at the same position. When loudspeakers are used to transmit the signals, it is necessary to pass the signals intended for presentation at the listener's ears through a matrix of filters that provide the inverse of the matrix of transfer functions that relates the loudspeaker input signals to the listener's ear signals. The characteristics of such filter matrices are profoundly influenced by the conditioning of the matrix to be inverted. This filter design problem is reviewed here by representing the loudspeakers as simple point monopole sources the head of the listener as a rigid sphere. The case of a virtual acoustic imaging system that uses two loudspeakers in order to reproduce the signals at the two ears is first described in some detail and previous work is reviewed. It is confirmed that the time domain response of the reproduced field is of long duration at frequencies where the inversion problem is ill-conditioned. The influence of the presence of the listener's head on this time domain behaviour is also evaluated. The principle is then extended to four input-four output reproduction systems and the computational model is used to explain some previous experimental observations. Finally, the conditioning of five input-four output systems is also examined and shown to have some potentially desirable characteristics.

  15. Revealing Real-Time Emotional Responses: a Personalized Assessment based on Heartbeat Dynamics

    PubMed Central

    Valenza, Gaetano; Citi, Luca; Lanatá, Antonio; Scilingo, Enzo Pasquale; Barbieri, Riccardo

    2014-01-01

    Emotion recognition through computational modeling and analysis of physiological signals has been widely investigated in the last decade. Most of the proposed emotion recognition systems require relatively long-time series of multivariate records and do not provide accurate real-time characterizations using short-time series. To overcome these limitations, we propose a novel personalized probabilistic framework able to characterize the emotional state of a subject through the analysis of heartbeat dynamics exclusively. The study includes thirty subjects presented with a set of standardized images gathered from the international affective picture system, alternating levels of arousal and valence. Due to the intrinsic nonlinearity and nonstationarity of the RR interval series, a specific point-process model was devised for instantaneous identification considering autoregressive nonlinearities up to the third-order according to the Wiener-Volterra representation, thus tracking very fast stimulus-response changes. Features from the instantaneous spectrum and bispectrum, as well as the dominant Lyapunov exponent, were extracted and considered as input features to a support vector machine for classification. Results, estimating emotions each 10 seconds, achieve an overall accuracy in recognizing four emotional states based on the circumplex model of affect of 79.29%, with 79.15% on the valence axis, and 83.55% on the arousal axis. PMID:24845973

  16. Real-time Responsiveness for Ethics Oversight During Disaster Research.

    PubMed

    Eckenwiler, Lisa; Pringle, John; Boulanger, Renaud; Hunt, Matthew

    2015-11-01

    Disaster research has grown in scope and frequency. Research in the wake of disasters and during humanitarian crises--particularly in resource-poor settings--is likely to raise profound and unique ethical challenges for local communities, crisis responders, researchers, and research ethics committees (RECs). Given the ethical challenges, many have questioned how best to provide research ethics review and oversight. We contribute to the conversation concerning how best to ensure appropriate ethical oversight in disaster research and argue that ethical disaster research requires of researchers and RECs a particular sort of ongoing, critical engagement which may not be warranted in less exceptional research. We present two cases that typify the concerns disaster researchers and RECs may confront, and elaborate upon what this ongoing engagement might look like--how it might be conceptualized and utilized--using the concept of real-time responsiveness (RTR). The central aim of RTR, understood here as both an ethical ideal and practice, is to lessen the potential for research conducted in the wake of disasters to create, perpetuate, or exacerbate vulnerabilities and contribute to injustices suffered by disaster-affected populations. Well cultivated and deployed, we believe that RTR may enhance the moral capacities of researchers and REC members, and RECs as institutions where moral agency is nurtured and sustained.

  17. Improving OCD time to solution using Signal Response Metrology

    NASA Astrophysics Data System (ADS)

    Fang, Fang; Zhang, Xiaoxiao; Vaid, Alok; Pandev, Stilian; Sanko, Dimitry; Ramanathan, Vidya; Venkataraman, Kartik; Haupt, Ronny

    2016-03-01

    In recent technology nodes, advanced process and novel integration scheme have challenged the precision limits of conventional metrology; with critical dimensions (CD) of device reduce to sub-nanometer region. Optical metrology has proved its capability to precisely detect intricate details on the complex structures, however, conventional RCWA-based (rigorous coupled wave analysis) scatterometry has the limitations of long time-to-results and lack of flexibility to adapt to wide process variations. Signal Response Metrology (SRM) is a new metrology technique targeted to alleviate the consumption of engineering and computation resources by eliminating geometric/dispersion modeling and spectral simulation from the workflow. This is achieved by directly correlating the spectra acquired from a set of wafers with known process variations encoded. In SPIE 2015, we presented the results of SRM application in lithography metrology and control [1], accomplished the mission of setting up a new measurement recipe of focus/dose monitoring in hours. This work will demonstrate our recent field exploration of SRM implementation in 20nm technology and beyond, including focus metrology for scanner control; post etch geometric profile measurement, and actual device profile metrology.

  18. Unraveling the drivers of the storm time radiation belt response

    NASA Astrophysics Data System (ADS)

    Kilpua, E. K. J.; Hietala, H.; Turner, D. L.; Koskinen, H. E. J.; Pulkkinen, T. I.; Rodriguez, J. V.; Reeves, G. D.; Claudepierre, S. G.; Spence, H. E.

    2015-05-01

    We present a new framework to study the time evolution and dynamics of the outer Van Allen belt electron fluxes. The framework is entirely based on the large-scale solar wind storm drivers and their substructures. The Van Allen Probe observations, revealing the electron flux behavior throughout the outer belt, are combined with continuous, long-term (over 1.5 solar cycles) geosynchronous orbit data set from GOES and solar wind measurements A superposed epoch analysis, where we normalize the timescales for each substructure (sheath, ejecta, and interface region) allows us to avoid smearing effects and to distinguish the electron flux evolution during various driver structures. We show that the radiation belt response is not random: The electron flux variations are determined by the combined effect of the structured solar wind driver and prestorm electron flux levels. In particular, we find that loss mechanisms dominate during stream interface regions, coronal mass ejection (CME) ejecta, and sheaths while enhancements occur during fast streams trailing the stream interface or the CME.

  19. Separable responses to error, ambiguity, and reaction time in cingulo-opercular task control regions.

    PubMed

    Neta, Maital; Schlaggar, Bradley L; Petersen, Steven E

    2014-10-01

    The dorsal anterior cingulate (dACC), along with the closely affiliated anterior insula/frontal operculum, have been demonstrated to show three types of task control signals across a wide variety of tasks. One of these signals, a transient signal that is thought to represent performance feedback, shows greater activity to error than correct trials. Other work has found similar effects for uncertainty/ambiguity or conflict, though some argue that dACC activity is, instead, modulated primarily by other processes more reflected in reaction time. Here, we demonstrate that, rather than a single explanation, multiple information processing operations are crucial to characterizing the function of these brain regions, by comparing operations within a single paradigm. Participants performed two tasks in an fMRI experimental session: (1) deciding whether or not visually presented word pairs rhyme, and (2) rating auditorily presented single words as abstract or concrete. A pilot was used to identify ambiguous stimuli for both tasks (e.g., word pair: BASS/GRACE; single word: CHANGE). We found greater cingulo-opercular activity for errors and ambiguous trials than clear/correct trials, with a robust effect of reaction time. The effects of error and ambiguity remained when reaction time was regressed out, although the differences decreased. Further stepwise regression of response consensus (agreement across participants for each stimulus; a proxy for ambiguity) decreased differences between ambiguous and clear trials, but left error-related differences almost completely intact. These observations suggest that trial-wise responses in cingulo-opercular regions monitor multiple performance indices, including accuracy, ambiguity, and reaction time.

  20. SEPARABLE RESPONSES TO ERROR, AMBIGUITY, AND REACTION TIME IN CINGULO-OPERCULAR TASK CONTROL REGIONS

    PubMed Central

    Neta, Maital; Schlaggar, Bradley L.; Petersen, Steven E.

    2014-01-01

    The dorsal anterior cingulate (dACC), along with the closely affiliated anterior insula/frontal operculum have been demonstrated to show three types of task control signals across a wide variety of tasks. One of these signals, a transient signal that is thought to represent performance feedback, shows greater activity to error than correct trials. Other work has found similar effects for uncertainty/ambiguity or conflict, though some argue that dACC activity is, instead, modulated primarily by other processes more reflected in reaction time. Here, we demonstrate that, rather than a single explanation, multiple information processing operations are crucial to characterizing the function of these brain regions, by comparing operations within a single paradigm. Participants performed two tasks in an fMRI experimental session: (1) deciding whether or not visually presented word pairs rhyme, and (2) rating auditorily presented single words as abstract or concrete. A pilot was used to identify ambiguous stimuli for both tasks (e.g., word pair: BASS/GRACE; single word: CHANGE). We found greater cingulo-opercular activity for errors and ambiguous trials than clear/correct trials, with a robust effect of reaction time. The effects of error and ambiguity remained when reaction time was regressed out, although the differences decreased. Further stepwise regression of response consensus (agreement across participants for each stimulus; a proxy for ambiguity) decreased differences between ambiguous and clear trials, but left error-related differences almost completely intact. These observations suggest that trial-wise responses in cinguloopercular regions monitor multiple performance indices, including accuracy, ambiguity, and reaction time. PMID:24887509

  1. Structural Equation Model Approach to the Use of Response Times for Improving Estimation in Item Response Models

    ERIC Educational Resources Information Center

    Sen, Rohini

    2012-01-01

    In the last five decades, research on the uses of response time has extended into the field of psychometrics (Schnikpe & Scrams, 1999; van der Linden, 2006; van der Linden, 2007), where interest has centered around the usefulness of response time information in item calibration and person measurement within an item response theory. framework.…

  2. Bayesian Procedures for Identifying Aberrant Response-Time Patterns in Adaptive Testing

    ERIC Educational Resources Information Center

    van der Linden, Wim J.; Guo, Fanmin

    2008-01-01

    In order to identify aberrant response-time patterns on educational and psychological tests, it is important to be able to separate the speed at which the test taker operates from the time the items require. A lognormal model for response times with this feature was used to derive a Bayesian procedure for detecting aberrant response times.…

  3. Is the storm time response of the inner magnetospheric hot ions universally similar or driver dependent?

    NASA Astrophysics Data System (ADS)

    Liemohn, Michael W.; Katus, Roxanne

    2012-04-01

    The Hot Electron and Ion Drift Integrator (HEIDI) model was used to simulate all of the intense storms (Dstmin < -100 nT) from solar cycle 23 (1996-2005). These storms were classified according to their heliospheric driving structure, namely, either an interplanetary coronal mass ejection (ICME) or a corotating interaction region and its trailing high-speed stream (CIR/HSS). Five different HEIDI input combinations were used to create a large collection of numerical results, varying the plasma outer boundary condition and electric field description in the model. Statistical data-model analyses were conducted on the total energy content, yielding error estimates on the correlation coefficients and root-mean-square error values for each run set. The accuracy of each run set depends on the method of comparison and classification of the driver. For the correlation coefficients, the simulations using a local-time-dependent outer boundary condition were consistently better than those using a local-time-averaged (but high-time-resolution) nightside boundary condition, with the simplistic electric field being better than the self-consistent field description. For the root-mean-square error, the results are less conclusive. For the CIR/HSS-driven storms, those with the high-time-resolution boundary condition were systematically better than those with the local-time-dependent (but lower-time-resolution) boundary condition. For the ICME-driven storms, those run sets employing the self-consistent electric field calculation were systematically better than those using the simplistic electric field. The implication, therefore, is that the inner magnetospheric physical response to strong driving is, at least to some degree, fundamentally different depending on the heliospheric structure impacting geospace. Specifically, for an accurate SYMH* comparison, it is found that CIR/HSS events respond strongly to transient spikes in the plasma outer boundary condition, while ICME passages

  4. Improving Risk Characterizations Based on Time to Response

    DTIC Science & Technology

    1986-05-01

    response as a function of exposure . The type of modeling has generally been of the form where the frequency of response is modeled as a function of dose ...67 REFERENCES Armitage, P. (1982). The assessment of low- dose carcinogenicity. Biometrics 38 ( Supplement on Current Topics in Biostatistics and...important aspects of quantitative cancer risk assessment is to model the frequency of a carcinogenic response as a function of exposure . Most of the

  5. Time Evolution of Climate Response to Supervolcano Eruption

    NASA Astrophysics Data System (ADS)

    Stenchikov, G. L.

    2011-12-01

    A supervolcano could inject into the stratosphere enormous amount of SO2, in comparison with the recent historic eruptions, and therefore it is expected to produce strong reduction of the surface air temperature globally. However the climate response to stratospheric super-injections of sulfur-containing gases might not scale linearly with respect to the effects of moderate eruptions of the historic period. Here we find that, counter-intuitively, very large volcanic eruptions might cause climate warming, at least for a prolonged initial period after an eruption. Supervolcano eruptions like the Toba eruption 75,000 years ago have injected into the atmosphere hundreds of times more SO2 than the largest volcanic eruptions of the 20th century. The huge mass of sulfur from a Toba-size eruption could potentially produce a sulfate aerosol layer with optical depth of more than 40. However, the gas-to-particle conversion process might be effectively slowed down because SO2 and an initially formed relatively thin aerosol layer will absorb and reflect UV radiation, reducing actinic fluxes and OH production to almost zero within and below the SO2 layer. Therefore SO2 would not be quickly converted to sulfate aerosols, but would stay in the stratosphere for years. Because SO2, like ozone, is a strong greenhouse gas it would cause significant IR warming for an extended period until it will be converted to sulfate aerosols or removed. We have simulated Toba eruption using the NASA GISS ModelE, and find that coupled climate model results and available proxy data support this hypothesis.

  6. Modulation of Response Timing in ADHD, Effects of Reinforcement Valence and Magnitude

    ERIC Educational Resources Information Center

    Luman, Marjolein; Oosterlaan, Jaap; Sergeant, Joseph A.

    2008-01-01

    The present study investigated the impact of reinforcement valence and magnitude on response timing in children with ADHD. Children were required to estimate a 1-s interval, and both the median response time (response tendency) and the intrasubject-variability (response stability) were investigated. In addition, heart rate and skin conductance…

  7. The Influence of Different Response Consequences on Children's Preference for Time-Out

    ERIC Educational Resources Information Center

    Willoughby, R. H.

    1970-01-01

    Time-out from positive reinforcement was found to have a suppressive effect when the response alternative was reinforced with the same frequency as the punished response. When the response alternative was a response for which positive reinforcement had been withdrawn, time-out was significantly preferred. (MH)

  8. An Analysis of Variance Approach for the Estimation of Response Time Distributions in Tests

    ERIC Educational Resources Information Center

    Attali, Yigal

    2010-01-01

    Generalizability theory and analysis of variance methods are employed, together with the concept of objective time pressure, to estimate response time distributions and the degree of time pressure in timed tests. By estimating response time variance components due to person, item, and their interaction, and fixed effects due to item types and…

  9. Affectivity of Task, Rehearsal Time, and Physiological Response

    ERIC Educational Resources Information Center

    Baker, Walter M.; And Others

    1975-01-01

    The present experiment extended the research on the relation between language and physiology. Among the topics considered was the relation between physiological responses produced by subjects and the number of words they use in an oral presentation. (Author/RK)

  10. Effect of cranktrain torque on automotive timing chain drive responses

    SciTech Connect

    Hwang, S.J.

    1996-09-01

    An analytical model is developed to describe the torsional responses of the chain drive and crankshaft. The model is used to analyze system equilibrium, free vibration and forced responses. The equations of motion are linearized about the equilibrium to determine natural frequencies and mode shapes of the torsional modes. The forced responses of the system are investigated by including the excitations of valve train torque, gas combustion forces and inertia torques induced by the reciprocating motions of the piston and connecting rod. For an example engine considered, the free vibration analyses show the natural frequencies and the associated mode shapes. The forced responses display the resonant amplitudes of the system excited by the torques/forces. Experimental measurements from a test engine are used to confirm the theoretical predictions. The experimental measurements of the system`s natural frequencies and the forced amplitudes are in good agreement with the theoretical predictions.

  11. Response time consideration for digitalized safety instrumentation applied to research reactor

    SciTech Connect

    Sang Hoon Bae; Young Seok Suh; Han Ju Cha

    2015-07-01

    A digitalized NMS (Neutron Measurement System) has a better performance than an analogue type in aspects of operating, maintenance and calibration. But some limitations in this system were found in the response time due to the inherent digital filtering time. The response time requirement as a kind of safety requirement is a significant factor that should be met. To satisfy the requirements, two approaches are herein suggested in a practical manner. Modifying conditions of the trip parameters and adjusting the testing methodology were applied to relieve the response time requirement. For a further enhanced and realistic response time, revised requirements for the response time of digitalized NMS are proposed in this paper. (authors)

  12. Accuracy of real time noninvasive temperature measurements using magnetic resonance thermal imaging in patients treated for high grade extremity soft tissue sarcomas

    SciTech Connect

    Craciunescu, Oana I.; Stauffer, Paul R.; Soher, Brian J.; Wyatt, Cory R.; Arabe, Omar; Maccarini, Paolo; Das, Shiva K.; Cheng, Kung-Shan; Wong, Terence Z.; Jones, Ellen L.; Dewhirst, Mark W.; Vujaskovic, Zeljko; MacFall, James R.

    2009-11-15

    Purpose: To establish accuracy of real time noninvasive temperature measurements using magnetic resonance thermal imaging in patients treated for high grade extremity soft tissue sarcomas. Methods: Protocol patients with advanced extremity sarcomas were treated with external beam radiation therapy and hyperthermia. Invasive temperature measures were compared to noninvasive magnetic resonance thermal imaging (MRTI) at 1.5 T performed during hyperthermia. Volumetric temperature rise images were obtained using the proton resonance frequency shift (PRFS) technique during heating in a 140 MHz miniannular phased array applicator. MRTI temperature changes were compared to invasive measurements of temperature with a multisensor fiber optic probe inside a no. 15 g catheter in the tumor. Since the PRFS technique is sensitive to drifts in the primary imaging magnetic field, temperature change distributions were corrected automatically during treatment using temperature-stable reference materials to characterize field changes in 3D. The authors analyzed MRT images and compared, in evaluable treatments, MR-derived temperatures to invasive temperatures measured in extremity sarcomas. Small regions of interest (ROIs) were specified near each invasive sensor identified on MR images. Temperature changes in the interstitial sensors were compared to the corresponding ROI PRFS-based temperature changes over the entire treatment and over the steady-state period. Nonevaluable treatments (motion/imaging artifacts, noncorrectable drifts) were not included in the analysis. Results: The mean difference between MRTI and interstitial probe measurements was 0.91 deg. C for the entire heating time and 0.85 deg. C for the time at steady state. These values were obtained from both tumor and normal tissue ROIs. When the analysis is done on just the tumor ROIs, the mean difference for the whole power on time was 0.74 deg. C and during the period of steady state was 0.62 deg. C. Conclusions: The

  13. Anticipating by Pigeons Depends on Local Statistical Information in a Serial Response Time Task

    ERIC Educational Resources Information Center

    Froehlich, Alyson L.; Herbranson, Walter T.; Loper, Julia D.; Wood, David M.; Shimp, Charles P.

    2004-01-01

    Pigeons responded in a serial response time task patterned after that of M. J. Nissen and P. Bullemer (1987) with humans. Experiment 1 produced global facilitation: Response times in repeating lists of locations were faster than when locations were random. Response time to a spatial location was also a function of both that location's 1st- and…

  14. Limited information estimation of the diffusion-based item response theory model for responses and response times.

    PubMed

    Ranger, Jochen; Kuhn, Jörg-Tobias; Szardenings, Carsten

    2016-05-01

    Psychological tests are usually analysed with item response models. Recently, some alternative measurement models have been proposed that were derived from cognitive process models developed in experimental psychology. These models consider the responses but also the response times of the test takers. Two such models are the Q-diffusion model and the D-diffusion model. Both models can be calibrated with the diffIRT package of the R statistical environment via marginal maximum likelihood (MML) estimation. In this manuscript, an alternative approach to model calibration is proposed. The approach is based on weighted least squares estimation and parallels the standard estimation approach in structural equation modelling. Estimates are determined by minimizing the discrepancy between the observed and the implied covariance matrix. The estimator is simple to implement, consistent, and asymptotically normally distributed. Least squares estimation also provides a test of model fit by comparing the observed and implied covariance matrix. The estimator and the test of model fit are evaluated in a simulation study. Although parameter recovery is good, the estimator is less efficient than the MML estimator.

  15. Brainstem auditory evoked responses in man. 1: Effect of stimulus rise-fall time and duration

    NASA Technical Reports Server (NTRS)

    Hecox, K.; Squires, N.; Galambos, R.

    1975-01-01

    Short latency (under 10 msec) responses elicited by bursts of white noise were recorded from the scalps of human subjects. Response alterations produced by changes in the noise burst duration (on-time), inter-burst interval (off-time), and onset and offset shapes were analyzed. The latency of the most prominent response component, wave V, was markedly delayed with increases in stimulus rise time but was unaffected by changes in fall time. Increases in stimulus duration, and therefore in loudness, resulted in a systematic increase in latency. This was probably due to response recovery processes, since the effect was eliminated with increases in stimulus off-time. The amplitude of wave V was insensitive to changes in signal rise and fall times, while increasing signal on-time produced smaller amplitude responses only for sufficiently short off-times. It was concluded that wave V of the human auditory brainstem evoked response is solely an onset response.

  16. MCP PMT with high time response and linear output current for neutron time-of-flight detectors

    NASA Astrophysics Data System (ADS)

    Dolotov, A. S.; Konovalov, P. I.; Nurtdinov, R. I.

    2016-09-01

    A microchannel plate (MCP) photomultiplier tube (PMT) with a subnanosecond time response and a high linear output current has been developed. PMT is designed for detection of weak pulses of radiation in UV-, visible and nearer-IR ranges and can be used in neutron time-of-flight (nTOF) detectors in experiments on laser compression of thermonuclear fuel. The results of measurements of MCP PMT main parameters are presented: photocathode spectral sensitivity, gain, maximum linear output current, and time response.

  17. Clinical Evaluation of Spatial Accuracy of a Fusion Imaging Technique Combining Previously Acquired Computed Tomography and Real-Time Ultrasound for Imaging of Liver Metastases

    SciTech Connect

    Hakime, Antoine Deschamps, Frederic; Garcia Marques de Carvalho, Enio; Teriitehau, Christophe; Auperin, Anne; De Baere, Thierry

    2011-04-15

    Purpose: This study was designed to evaluate the spatial accuracy of matching volumetric computed tomography (CT) data of hepatic metastases with real-time ultrasound (US) using a fusion imaging system (VNav) according to different clinical settings. Methods: Twenty-four patients with one hepatic tumor identified on enhanced CT and US were prospectively enrolled. A set of three landmarks markers was chosen on CT and US for image registration. US and CT images were then superimposed using the fusion imaging display mode. The difference in spatial location between the tumor visible on the CT and the US on the overlay images (reviewer no. 1, comment no. 2) was measured in the lateral, anterior-posterior, and vertical axis. The maximum difference (Dmax) was evaluated for different predictive factors.CT performed 1-30 days before registration versus immediately before. Use of general anesthesia for CT and US versus no anesthesia.Anatomic landmarks versus landmarks that include at least one nonanatomic structure, such as a cyst or a calcificationResultsOverall, Dmax was 11.53 {+-} 8.38 mm. Dmax was 6.55 {+-} 7.31 mm with CT performed immediately before VNav versus 17.4 {+-} 5.18 with CT performed 1-30 days before (p < 0.0001). Dmax was 7.05 {+-} 6.95 under general anesthesia and 16.81 {+-} 6.77 without anesthesia (p < 0.0015). Landmarks including at least one nonanatomic structure increase Dmax of 5.2 mm (p < 0.0001). The lowest Dmax (1.9 {+-} 1.4 mm) was obtained when CT and VNav were performed under general anesthesia, one immediately after the other. Conclusions: VNav is accurate when adequate clinical setup is carefully selected. Only under these conditions (reviewer no. 2), liver tumors not identified on US can be accurately targeted for biopsy or radiofrequency ablation using fusion imaging.

  18. Diagnostic accuracy of two multiplex real-time polymerase chain reaction assays for the diagnosis of meningitis in children in a resource-limited setting

    PubMed Central

    Khumalo, Jermaine; Nicol, Mark; Hardie, Diana; Muloiwa, Rudzani; Mteshana, Phindile

    2017-01-01

    Introduction Accurate etiological diagnosis of meningitis is important, but difficult in resource-limited settings due to prior administration of antibiotics and lack of viral diagnostics. We aimed to develop and validate 2 real-time multiplex PCR (RT-PCR) assays for the detection of common causes of community-acquired bacterial and viral meningitis in South African children. Methods We developed 2 multiplex RT- PCRs for detection of S. pneumoniae, N. meningitidis, H. influenzae, enteroviruses, mumps virus and herpes simplex virus. We tested residual CSF samples from children presenting to a local paediatric hospital over a one-year period, whose CSF showed an abnormal cell count. Results were compared with routine diagnostic tests and the final discharge diagnosis. We calculated accuracy of the bacterial RT-PCR assay compared to CSF culture and using World Health Organisation definitions of laboratory-confirmed bacterial meningitis. Results From 292 samples, bacterial DNA was detected in 12 (4.1%) and viral nucleic acids in 94 (32%). Compared to CSF culture, the sensitivity and specificity of the bacterial RT-PCR was 100% and 97.2% with complete agreement in organism identification. None of the cases positive by viral RT-PCR had a bacterial cause confirmed on CSF culture. Only 9/90 (10%) of patients diagnosed clinically as bacterial meningitis or partially treated bacterial meningitis tested positive with the bacterial RT-PCR. Discussion In this population the use of 2 multiplex RT-PCRs targeting 6 common pathogens gave promising results. If introduced into routine diagnostic testing, these multiplex RT-PCR assays would supplement other diagnostic tests, and have the potential to limit unnecessary antibiotic therapy and hospitalisation. PMID:28346504

  19. Temperate grass response to extent and timing of grazing

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Considerable differences exist among cool-season grass species in their production potential and response to management variables. We examined the effects of grazing management on forage and root production of two temperate perennial grasses, meadow fescue [Schedonoruspratensis (Huds.) P. Beauv.] an...

  20. Leveraging First Response Time into the Knowledge Tracing Model

    ERIC Educational Resources Information Center

    Wang, Yutao; Heffernan, Neil T.

    2012-01-01

    The field of educational data mining has been using the Knowledge Tracing model, which only look at the correctness of student first response, for tracking student knowledge. Recently, lots of other features are studied to extend the Knowledge Tracing model to better model student knowledge. The goal of this paper is to analyze whether or not the…

  1. Timing and Tuning for Familiarity of Cortical Responses to Faces

    PubMed Central

    Bobes, Maria A.; Lage Castellanos, Agustin; Quiñones, Ileana; García, Lorna; Valdes-Sosa, Mitchell

    2013-01-01

    Different kinds of known faces activate brain areas to dissimilar degrees. However, the tuning to type of knowledge, and the temporal course of activation, of each area have not been well characterized. Here we measured, with functional magnetic resonance imaging, brain activity elicited by unfamiliar, visually familiar, and personally-familiar faces. We assessed response amplitude and duration using flexible hemodynamic response functions, as well as the tuning to face type, of regions within the face processing system. Core face processing areas (occipital and fusiform face areas) responded to all types of faces with only small differences in amplitude and duration. In contrast, most areas of the extended face processing system (medial orbito-frontal, anterior and posterior cingulate) had weak responses to unfamiliar and visually-familiar faces, but were highly tuned and exhibited prolonged responses to personally-familiar faces. This indicates that the neural processing of different types of familiar faces not only differs in degree, but is probably mediated by qualitatively distinct mechanisms. PMID:24130761

  2. Utilizing Response Time Distributions for Item Selection in CAT

    ERIC Educational Resources Information Center

    Fan, Zhewen; Wang, Chun; Chang, Hua-Hua; Douglas, Jeffrey

    2012-01-01

    Traditional methods for item selection in computerized adaptive testing only focus on item information without taking into consideration the time required to answer an item. As a result, some examinees may receive a set of items that take a very long time to finish, and information is not accrued as efficiently as possible. The authors propose two…

  3. Online versus offline: The Web as a medium for response time data collection.

    PubMed

    Chetverikov, Andrey; Upravitelev, Philipp

    2016-09-01

    The Internet provides a convenient environment for data collection in psychology. Modern Web programming languages, such as JavaScript or Flash (ActionScript), facilitate complex experiments without the necessity of experimenter presence. Yet there is always a question of how much noise is added due to the differences between the setups used by participants and whether it is compensated for by increased ecological validity and larger sample sizes. This is especially a problem for experiments that measure response times (RTs), because they are more sensitive (and hence more susceptible to noise) than, for example, choices per se. We used a simple visual search task with different set sizes to compare laboratory performance with Web performance. The results suggest that although the locations (means) of RT distributions are different, other distribution parameters are not. Furthermore, the effect of experiment setting does not depend on set size, suggesting that task difficulty is not important in the choice of a data collection method. We also collected an additional online sample to investigate the effects of hardware and software diversity on the accuracy of RT data. We found that the high diversity of browsers, operating systems, and CPU performance may have a detrimental effect, though it can partly be compensated for by increased sample sizes and trial numbers. In sum, the findings show that Web-based experiments are an acceptable source of RT data, comparable to a common keyboard-based setup in the laboratory.

  4. Recall and response time norms for English-Swahili word pairs and facts about Kenya.

    PubMed

    Bangert, Ashley S; Heydarian, Nazanin M

    2016-01-28

    In the vast literature exploring learning, many studies have used paired-associate stimuli, despite the fact that real-world learning involves many different types of information. One of the most popular materials used in studies of learning has been a set of Swahili-English word pairs for which Nelson and Dunlosky (Memory 2; 325-335, 1994) published recall norms two decades ago. These norms involved use of the Swahili words as cues to facilitate recall of the English translation. It is unclear whether cueing in the opposite direction (from English to Swahili) would lead to symmetric recall performance. Bilingual research has suggested that translation in these two different directions involves asymmetric links that may differentially impact recall performance, depending on which language is used as the cue (Kroll & Stewart, Journal of Memory and Language 33; 149-174,1994). Moreover, the norms for these and many other learning stimuli have typically been gathered from college students. In the present study, we report recall accuracy and response time norms for Swahili words when they are cued by their English translations. We also report norms for a companion set of fact stimuli that may be used along with the Swahili-English word pairs to assess learning on a broader scale across different stimulus materials. Data were collected using Amazon's Mechanical Turk to establish a sample that was diverse in both age and ethnicity. These different, but related, stimulus sets will be applicable to studies of learning, metacognition, and memory in diverse samples.

  5. Eocene oceanic responses to orbital forcing on precessional time scales

    NASA Astrophysics Data System (ADS)

    Sloan, L. Cirbus; Huber, Matthew

    2001-02-01

    The goal of our study was to gain an estimate of the variability of ocean-related climate processes driven by insolation forcing over a realistic precessional cycle in an Eocene greenhouse world. Between endmembers of a precessional cycle mean annual sea surface temperatures (SSTs) vary by up to 5°C at high northern latitudes, with minimal tropical SST response. Extratropical regions of the Pacific, Atlantic, and Tethys Oceans show up to a two-fold variation in upwelling strength, while oceanic regions adjacent to northwestern Africa, India, and South America exhibit little oceanic upweliing variability. The response of ocean surface moisture balance to the forcing is greatest in the tropics, varying by as much as 60%. Continental runoff varies by up to a factor of two in some regions. These results may be useful in identifying locations with maximum likelihood of future recovery of orbital cyclicity in deep-sea sediments.

  6. 13 CFR 102.4 - Timing of responses to requests.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... substantial subject matter interest therein. (b) Additional time. Where an extension of more than ten working..., if one of the following conditions is met: (i) You demonstrate someone's life or physical safety...

  7. 13 CFR 102.4 - Timing of responses to requests.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... substantial subject matter interest therein. (b) Additional time. Where an extension of more than ten working..., if one of the following conditions is met: (i) You demonstrate someone's life or physical safety...

  8. 5 CFR 1820.4 - Timing of responses to requests.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... threat to the life or physical safety of an individual; (ii) With respect to a request made by a person... involving unusual circumstances, as defined by the FOIA, supporting an extension of time to respond, and...

  9. Real-time earthquake monitoring: Early warning and rapid response

    NASA Technical Reports Server (NTRS)

    1991-01-01

    A panel was established to investigate the subject of real-time earthquake monitoring (RTEM) and suggest recommendations on the feasibility of using a real-time earthquake warning system to mitigate earthquake damage in regions of the United States. The findings of the investigation and the related recommendations are described in this report. A brief review of existing real-time seismic systems is presented with particular emphasis given to the current California seismic networks. Specific applications of a real-time monitoring system are discussed along with issues related to system deployment and technical feasibility. In addition, several non-technical considerations are addressed including cost-benefit analysis, public perceptions, safety, and liability.

  10. 40 CFR 1601.24 - Timing of responses to requests.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... two processing tracks by distinguishing between simple and more complex requests based on the amount of work and/or time needed to process the request, including according to limits based on the...

  11. 28 CFR 16.5 - Timing of responses to requests.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... distinguishing between simple and more complex requests based on the amount of work and/or time needed to process the request, including through limits based on the number of pages involved. If a component does...

  12. 38 CFR 1.556 - Timing of responses to requests.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... complex, based upon the amount of work and/or time needed to process the request, including consideration of the number of pages involved. (2) The FOIA Officer shall advise the requester of the track...

  13. Technical note: Update on response times, in-air measurements, and in situ drift for oxygen optodes on profiling platforms

    NASA Astrophysics Data System (ADS)

    Bittig, Henry C.; Körtzinger, Arne

    2017-01-01

    Oxygen optode measurements on floats and gliders suffer from a slow time response and various sources of drift in the calibration coefficients. Based on two dual-O2 Argo floats, we show how to post-correct for the effect of the optode's time response and give an update on optode in situ drift stability and in-air calibration. Both floats are equipped with an unpumped Aanderaa 4330 optode and a pumped Sea-Bird SBE63 optode. Response times for the pumped SBE63 were derived following Bittig et al. (2014) and the same methods were used to correct the time response bias. Using both optodes on each float, the time response regime of the unpumped Aanderaa optode was characterized more accurately than previously possible. Response times for the pumped SBE63 on profiling floats are in the range of 25-40 s, while they are between 60 and 95 s for the unpumped 4330 optode. Our parameterization can be employed to post-correct the slow optode time response on floats and gliders. After correction, both sensors agree to within 2-3 µmol kg-1 (median difference) in the strongest gradients (120 µmol kg-1 change over 8 min or 20 dbar) and better elsewhere. However, time response correction is only possible if measurement times are known, i.e., provided by the platform as well as transmitted and stored with the data. The O2 in-air measurements show a significant in situ optode drift of -0.40 and -0.27 % yr-1 over the available 2 and 3 years of deployment, respectively. Optode in-air measurements are systematically biased high during midday surfacings compared to dusk, dawn, and nighttime. While preference can be given to nighttime surfacings to avoid this in-air calibration bias, we suggest a parameterization of the daytime effect as a function of the Sun's elevation to be able to use all data and to better constrain the result. Taking all effects into account, calibration factors have an uncertainty of 0.1 %. In addition, in-air calibration factors vary by 0.1-0.2 % when using

  14. Enabling high grayscale resolution displays and accurate response time measurements on conventional computers.

    PubMed

    Li, Xiangrui; Lu, Zhong-Lin

    2012-02-29

    Display systems based on conventional computer graphics cards are capable of generating images with 8-bit gray level resolution. However, most experiments in vision research require displays with more than 12 bits of luminance resolution. Several solutions are available. Bit++ (1) and DataPixx (2) use the Digital Visual Interface (DVI) output from graphics cards and high resolution (14 or 16-bit) digital-to-analog converters to drive analog display devices. The VideoSwitcher (3) described here combines analog video signals from the red and blue channels of graphics cards with different weights using a passive resister network (4) and an active circuit to deliver identical video signals to the three channels of color monitors. The method provides an inexpensive way to enable high-resolution monochromatic displays using conventional graphics cards and analog monitors. It can also provide trigger signals that can be used to mark stimulus onsets, making it easy to synchronize visual displays with physiological recordings or response time measurements. Although computer keyboards and mice are frequently used in measuring response times (RT), the accuracy of these measurements is quite low. The RTbox is a specialized hardware and software solution for accurate RT measurements. Connected to the host computer through a USB connection, the driver of the RTbox is compatible with all conventional operating systems. It uses a microprocessor and high-resolution clock to record the identities and timing of button events, which are buffered until the host computer retrieves them. The recorded button events are not affected by potential timing uncertainties or biases associated with data transmission and processing in the host computer. The asynchronous storage greatly simplifies the design of user programs. Several methods are available to synchronize the clocks of the RTbox and the host computer. The RTbox can also receive external triggers and be used to measure RT with respect

  15. 75 FR 37712 - Temporary Suspension of Certain Oil Spill Response Time Requirements To Support Deepwater Horizon...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-30

    ...; 2050-AG63 Temporary Suspension of Certain Oil Spill Response Time Requirements To Support Deepwater Horizon Oil Spill of National Significance (SONS) Response AGENCIES: Coast Guard, DHS, and Environmental... Environmental Protection Agency (EPA) temporary interim rule will suspend oil spill response time...

  16. 49 CFR 234.103 - Timely response to report of malfunction.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Timely response to report of malfunction. 234.103..., AND EMERGENCY NOTIFICATION SYSTEMS Response to Credible Reports of Warning System Malfunction at Highway-Rail Grade Crossings § 234.103 Timely response to report of malfunction. (a) Upon receipt of...

  17. 49 CFR 234.103 - Timely response to report of malfunction.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Timely response to report of malfunction. 234.103..., AND EMERGENCY NOTIFICATION SYSTEMS Response to Credible Reports of Warning System Malfunction at Highway-Rail Grade Crossings § 234.103 Timely response to report of malfunction. (a) Upon receipt of...

  18. The Impact of Item Format and Examinee Characteristics on Response Times

    ERIC Educational Resources Information Center

    Hess, Brian J.; Johnston, Mary M.; Lipner, Rebecca S.

    2013-01-01

    Current research on examination response time has focused on tests comprised of traditional multiple-choice items. Consequently, the impact of other innovative or complex item formats on examinee response time is not understood. The present study used multilevel growth modeling to investigate examinee characteristics associated with response time…

  19. A theoretical model for fluvial channel response time during time-dependent climatic and tectonic forcing and its inverse applications

    NASA Astrophysics Data System (ADS)

    Goren, Liran

    2016-10-01

    The fluvial response time dictates the duration of fluvial channel adjustment in response to changing climatic and tectonic conditions. However, when these conditions vary continuously, the channel cannot equilibrate and the response time is not well defined. Here I develop an analytical solution to the linear stream power model of fluvial incision that predicts the channel topography as a function of time-dependent climatic and tectonic conditions. From this solution, a general definition of the fluvial response time emerges: the duration over which the tectonic history needs to be known to evaluate channel topography. This new definition is used in linear inversion schemes for inferring climatic or tectonic histories from river long profiles. The analytic solution further reveals that high-frequency climatic oscillations, such as Milankovitch cycles, are not expected to leave significant fingerprints on the long profiles of fluvially incised detachment-limited rivers.

  20. Accuracy of genotyping using the TaqMan PCR assay for single nucleotide polymorphisms responsible for thiopurine sensitivity in Japanese patients with inflammatory bowel disease.

    PubMed

    Osaki, Rie; Imaeda, Hirotsugu; Ban, Hiromitsu; Aomatsu, Tomoki; Bamba, Shigeki; Tsujikawa, Tomoyuki; Sasaki, Masaya; Fujiyama, Yoshihide; Andoh, Akira

    2011-09-01

    Thiopurine drugs are the most common drugs used to maintain clinical remission in inflammatory bowel disease (IBD). Three single-nucleotide polymorphisms (SNPs), TPMT A719G (rs1142345), inosine triphosphate pyrophosphatase (ITPase) C94A (rs1127354) and multidrug resistance protein 4 MRP4 G2269A (rs3765534), have been reported to account for heightened sensitivity to thiopurine drugs in the Japanese population. We investigated the usefulness of the TaqMan(®) PCR assay (Applied Biosystems) for the rapid detection of these SNPs to improve the safety of thiopurine therapy. We enrolled 44 healthy volunteers and 235 IBD patients. Genotyping of the SNPs was performed using Custom TaqMan SNP genotyping assays, direct sequencing and PCR-RFLP. Genotyping for MRP4 G2269A by the TaqMan PCR assay was successfully achieved in all samples. Comparison with our previous data using direct sequencing indicated one discordant result, and re-sequencing showed that the TaqMan PCR assay was correct. The overall accuracy of the TaqMan assay for MRP4 G2269A was 100%. The TaqMan PCR genotyping for TPMT A719G and ITPase C94A was successfully performed in all samples. The results of TPMT A719G by the TaqMan assay were identical with those of PCR-RFLP. In ITPase C94A, a comparison of the TaqMan assay and PCR-RFLP yielded 12 discordant results, and direct sequencing showed that the TaqMan PCR assay was correct. The allelic frequency determined by the TaqMan assay was 0.145 for MRP4 G2269A, 0.009 for TPMT A719G and 0.121 for ITPase C94A, respectively. In conclusion, the TaqMan(®) PCR assay is useful for genotyping of SNPs responsible for thiopurine sensitivity in Japanese IBD patients.

  1. A Multivariate Multilevel Approach to the Modeling of Accuracy and Speed of Test Takers

    ERIC Educational Resources Information Center

    Klein Entink, R. H.; Fox, J. P.; van der Linden, W. J.

    2009-01-01

    Response times on test items are easily collected in modern computerized testing. When collecting both (binary) responses and (continuous) response times on test items, it is possible to measure the accuracy and speed of test takers. To study the relationships between these two constructs, the model is extended with a multivariate multilevel…

  2. High Accuracy Fuel Flowmeter, Phase 1

    NASA Technical Reports Server (NTRS)

    Mayer, C.; Rose, L.; Chan, A.; Chin, B.; Gregory, W.

    1983-01-01

    Technology related to aircraft fuel mass - flowmeters was reviewed to determine what flowmeter types could provide 0.25%-of-point accuracy over a 50 to one range in flowrates. Three types were selected and were further analyzed to determine what problem areas prevented them from meeting the high accuracy requirement, and what the further development needs were for each. A dual-turbine volumetric flowmeter with densi-viscometer and microprocessor compensation was selected for its relative simplicity and fast response time. An angular momentum type with a motor-driven, spring-restrained turbine and viscosity shroud was selected for its direct mass-flow output. This concept also employed a turbine for fast response and a microcomputer for accurate viscosity compensation. The third concept employed a vortex precession volumetric flowmeter and was selected for its unobtrusive design. Like the turbine flowmeter, it uses a densi-viscometer and microprocessor for density correction and accurate viscosity compensation.

  3. Brainstem auditory evoked responses in man. 1: Effect of stimulus rise-fall time and duration

    NASA Technical Reports Server (NTRS)

    Hecox, K.; Squires, N.; Galambos, R.

    1975-01-01

    Short latency (under 10 msec) evoked responses elicited by bursts of white noise were recorded from the scalp of human subjects. Response alterations produced by changes in the noise burst duration (on-time) inter-burst interval (off-time), and onset and offset shapes are reported and evaluated. The latency of the most prominent response component, wave V, was markedly delayed with increases in stimulus rise-time but was unaffected by changes in fall-time. The amplitude of wave V was insensitive to changes in signal rise-and-fall times, while increasing signal on-time produced smaller amplitude responses only for sufficiently short off-times. It is concluded that wave V of the human auditory brainstem evoked response is solely an onset response.

  4. Sequential Dependencies in Interresponse Times and Reinforcement/Response-Cost

    ERIC Educational Resources Information Center

    Kawashima, Kentaro

    2004-01-01

    This study investigates sequential dependencies in interresponse times (IRTs) produced by human subjects under random-ratio (RR) and staircase stochastic reinforcement of waiting (staircase SRW) schedules using autocorrelation and relative frequencies of IRT[subscript n] *IRT[subscript n+1] pairs. In the first of two experiments conducted for this…

  5. 45 CFR 612.5 - Timing of responses to requests.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... to ten working days. (2) Where the extension is for more than ten working days, the FOIA Officer or... it may be processed within the ten day extension period or to arrange an agreed upon alternative time... expected to pose an imminent threat to the life or physical safety of an individual; or (B) An urgency...

  6. INTERNAL DOSE AND RESPONSE IN REAL-TIME.

    EPA Science Inventory

    Abstract: Rapid temporal fluctuations in exposure may occur in a number of situations such as accidents or other unexpected acute releases of airborne substances. Often risk assessments overlook temporal exposure patterns under simplifying assumptions such as the use of time-wei...

  7. Physiological Evidence for Response Inhibition in Choice Reaction Time Tasks

    ERIC Educational Resources Information Center

    Burle, Boris; Vidal, Frank; Tandonnet, Christophe; Hasbroucq, Thierry

    2004-01-01

    Inhibition is a widely used notion proposed to account for data obtained in choice reaction time (RT) tasks. However, this concept is weakly supported by empirical facts. In this paper, we review a series of experiments using Hoffman reflex, transcranial magnetic stimulation and electroencephalography to study inhibition in choice RT tasks. We…

  8. Time-Varying Affective Response for Humanoid Robots

    NASA Astrophysics Data System (ADS)

    Moshkina, Lilia; Arkin, Ronald C.; Lee, Jamee K.; Jung, Hyunryong

    This paper describes the design of a complex time-varying affective architecture. It is an expansion of the TAME architecture (traits, attitudes, moods, and emotions) as applied to humanoid robotics. It particular it is intended to promote effective human-robot interaction by conveying the robot’s affective state to the user in an easy-to-interpret manner.

  9. Harnessing data structure for recovery of randomly missing structural vibration responses time history: Sparse representation versus low-rank structure

    NASA Astrophysics Data System (ADS)

    Yang, Yongchao; Nagarajaiah, Satish

    2016-06-01

    Randomly missing data of structural vibration responses time history often occurs in structural dynamics and health monitoring. For example, structural vibration responses are often corrupted by outliers or erroneous measurements due to sensor malfunction; in wireless sensing platforms, data loss during wireless communication is a common issue. Besides, to alleviate the wireless data sampling or communication burden, certain accounts of data are often discarded during sampling or before transmission. In these and other applications, recovery of the randomly missing structural vibration responses from the available, incomplete data, is essential for system identification and structural health monitoring; it is an ill-posed inverse problem, however. This paper explicitly harnesses the data structure itself-of the structural vibration responses-to address this (inverse) problem. What is relevant is an empirical, but often practically true, observation, that is, typically there are only few modes active in the structural vibration responses; hence a sparse representation (in frequency domain) of the single-channel data vector, or, a low-rank structure (by singular value decomposition) of the multi-channel data matrix. Exploiting such prior knowledge of data structure (intra-channel sparse or inter-channel low-rank), the new theories of ℓ1-minimization sparse recovery and nuclear-norm-minimization low-rank matrix completion enable recovery of the randomly missing or corrupted structural vibration response data. The performance of these two alternatives, in terms of recovery accuracy and computational time under different data missing rates, is investigated on a few structural vibration response data sets-the seismic responses of the super high-rise Canton Tower and the structural health monitoring accelerations of a real large-scale cable-stayed bridge. Encouraging results are obtained and the applicability and limitation of the presented methods are discussed.

  10. Complexity, Accuracy, and Fluency as Properties of Language Performance: The Development of the Multiple Subsystems over Time and in Relation to Each Other

    ERIC Educational Resources Information Center

    Vercellotti, Mary Lou

    2012-01-01

    Applied linguists have identified three components of second language (L2) performance: complexity, accuracy, and fluency (CAF) to measure L2 development. Many studies researching CAF found trade-off effects (in which a higher performance in one component corresponds to lower performance in another) during tasks, often in online oral language…

  11. Quantized response times are a signature of a neuronal bottleneck in decision

    PubMed Central

    Perona, Pietro

    2014-01-01

    The histograms of response times of optimal YES/NO decisions that are computed from a single sensory Poisson neuron are highly structured. In particular, response times in NO decisions are quantized to a small set of times, while response times in YES decisions have a multimodal structure. Both the times of NO decisions, as well as the modes of the the histogram of YES decisions, are associated to the number of action potentials that were necessary to reach the decision. Their value is a function of the firing rate of the neuron in response to the states of the stimulus. PMID:24782750

  12. Response-Time Approach to Contrasting Models of Perceptual Classification

    DTIC Science & Technology

    2013-02-01

    For example, in Experiment 1 of Nosofsky et al. (2011), the stimuli were a set of 27 Munsell colors varying along dimensions of hue , saturation, and...develop and test models that explain the time course of classification and recognition decision making. The first specific goal involved the...Several empirical studies demonstrated successful applications of the new theory in this domain. The second goal involved the development and testing

  13. Rapid response teams in adult hospitals: time for another look?

    PubMed

    White, K; Scott, I A; Vaux, A; Sullivan, C M

    2015-12-01

    Rapid response teams (RRT), alternatively termed medical emergency teams, have become part of the clinical landscape in the majority of adult hospitals throughout Australia and New Zealand. These teams aim to bring critical care expertise to the bedside of clinically deteriorating patients residing in general hospital wards with the aim of preventing adverse outcomes, in particular death or cardiorespiratory arrests. While the concept of RRT has considerable face validity, there is little high quality evidence of their effectiveness and much uncertainty as to the optimal methods for identifying patients in need of RRT and calling the RRT (afferent limb) and how, and with whom, the RRT should then respond (efferent limb). Adverse unintended consequences of RRT systems and the opportunity costs involved in maintaining such systems have not been subject to study, amid concerns RRT may be compensating for other potentially remediable system of care failures. This article presents an overview of the current state of play of RRT in hospital practice as they pertain to the care of adult patients and identifies several issues around their implementation and evaluation that should be subject to further research.

  14. Time-Dependent Response Versus Scan Angle for MODIS Reflective Solar Bands

    NASA Technical Reports Server (NTRS)

    Sun, Junqiang; Xiong, Xiaoxiong; Angal, Amit; Chen, Hongda; Wu, Aisheng; Geng, Xu

    2014-01-01

    The Moderate Resolution Imaging Spectroradiometer (MODIS) instruments currently operate onboard the National Aeronautics and Space Administration (NASA's) Terra and Aqua spacecraft, launched on December 18, 1999 and May 4, 2002, respectively. MODIS has 36 spectral bands, among which 20 are reflective solar bands (RSBs) covering a spectral range from 0.412 to 2.13 µm. The RSBs are calibrated on orbit using a solar diffuser (SD) and an SD stability monitor and with additional measurements from lunar observations via a space view (SV) port. Selected pseudo-invariant desert sites are also used to track the RSB on-orbit gain change, particularly for short-wavelength bands. MODIS views the Earth surface, SV, and the onboard calibrators using a two-sided scan mirror. The response versus scan angle (RVS) of the scan mirror was characterized prior to launch, and its changes are tracked using observations made at different angles of incidence from onboard SD, lunar, and Earth view (EV) measurements. These observations show that the optical properties of the scan mirror have experienced large wavelength-dependent degradation in both the visible and near infrared spectral regions. Algorithms have been developed to track the on-orbit RVS change using the calibrators and the selected desert sites. These algorithms have been applied to both Terra and Aqua MODIS Level 1B (L1B) to improve the EV data accuracy since L1B Collection 4, refined in Collection 5, and further improved in the latest Collection 6 (C6). In C6, two approaches have been used to derive the time-dependent RVS for MODIS RSB. The first approach relies on data collected from sensor onboard calibrators and mirror side ratios from EV observations. The second approach uses onboard calibrators and EV response trending from selected desert sites. This approach is mainly used for the bands with much larger changes in their time-dependent RVS, such as the Terra MODIS bands 1-4, 8, and 9 and the Aqua MODIS bands 8- and 9

  15. Do Young and Old Preschoolers Exhibit Response Bias Due to Different Mechanisms? Investigating Children's Response Time

    ERIC Educational Resources Information Center

    Okanda, Mako; Itakura, Shoji

    2011-01-01

    Previous studies have suggested that younger preschoolers exhibit a yes bias due to underdeveloped cognitive abilities, whereas older preschoolers exhibit a response bias due to other factors. To test this hypothesis, we investigated the response latency to yes-no questions pertaining to familiar and unfamiliar objects in 3- to 6-year-olds. The…

  16. Abrupt rise of new machine ecology beyond human response time

    PubMed Central

    Johnson, Neil; Zhao, Guannan; Hunsader, Eric; Qi, Hong; Johnson, Nicholas; Meng, Jing; Tivnan, Brian

    2013-01-01

    Society's techno-social systems are becoming ever faster and more computer-orientated. However, far from simply generating faster versions of existing behaviour, we show that this speed-up can generate a new behavioural regime as humans lose the ability to intervene in real time. Analyzing millisecond-scale data for the world's largest and most powerful techno-social system, the global financial market, we uncover an abrupt transition to a new all-machine phase characterized by large numbers of subsecond extreme events. The proliferation of these subsecond events shows an intriguing correlation with the onset of the system-wide financial collapse in 2008. Our findings are consistent with an emerging ecology of competitive machines featuring ‘crowds' of predatory algorithms, and highlight the need for a new scientific theory of subsecond financial phenomena. PMID:24022120

  17. Driver Vision Based Perception-Response Time Prediction and Assistance Model on Mountain Highway Curve.

    PubMed

    Li, Yi; Chen, Yuren

    2016-12-30

    To make driving assistance system more humanized, this study focused on the prediction and assistance of drivers' perception-response time on mountain highway curves. Field tests were conducted to collect real-time driving data and driver vision information. A driver-vision lane model quantified curve elements in drivers' vision. A multinomial log-linear model was established to predict perception-response time with traffic/road environment information, driver-vision lane model, and mechanical status (last second). A corresponding assistance model showed a positive impact on drivers' perception-response times on mountain highway curves. Model results revealed that the driver-vision lane model and visual elements did have important influence on drivers' perception-response time. Compared with roadside passive road safety infrastructure, proper visual geometry design, timely visual guidance, and visual information integrality of a curve are significant factors for drivers' perception-response time.

  18. Driver Vision Based Perception-Response Time Prediction and Assistance Model on Mountain Highway Curve

    PubMed Central

    Li, Yi; Chen, Yuren

    2016-01-01

    To make driving assistance system more humanized, this study focused on the prediction and assistance of drivers’ perception-response time on mountain highway curves. Field tests were conducted to collect real-time driving data and driver vision information. A driver-vision lane model quantified curve elements in drivers’ vision. A multinomial log-linear model was established to predict perception-response time with traffic/road environment information, driver-vision lane model, and mechanical status (last second). A corresponding assistance model showed a positive impact on drivers’ perception-response times on mountain highway curves. Model results revealed that the driver-vision lane model and visual elements did have important influence on drivers’ perception-response time. Compared with roadside passive road safety infrastructure, proper visual geometry design, timely visual guidance, and visual information integrality of a curve are significant factors for drivers’ perception-response time. PMID:28042851

  19. Performance on a simple response time task: Is sleep or work more important for miners?

    PubMed

    Ferguson, Sally A; Paech, Gemma M; Dorrian, Jillian; Roach, Gregory D; Jay, Sarah M

    2011-01-01

    The purpose of the current study was to investigate the impact of work- and sleep-related factors on an objective measure of response time in a field setting. Thirty-five mining operators working 12-h shift patterns completed daily sleep and work diaries, wore activity monitors continuously and completed palm-based psychomotor vigilance tests (palmPVT) at the start and end of each shift. Linear mixed models were used to test the main effects on response time of roster, timing of test, sleep history and prior wake. The time at which the test occurred was a significant predictor of response time (F₃(,)₄₀₃(.)₄ = 6.72, p < .01) with the end of night shifts being associated with significantly slower response times than the start of night shifts, and the start or end of day shifts. Further, the amount of sleep obtained in the 24h prior to the test was also a significant predictor of response time (F₃(,)₄₀₇(.)₀ = 3.05, p < .01). The results suggest that, as expected, the end of night shift is associated with changes in response time indicative of performance impairments. Of more interest however is that immediate sleep history was also predictive of changes in response time with lower amounts of prior sleep related to slower response times. The current data provides further evidence that sleep is a primary mediator of performance, independent of roster pattern.

  20. Linking impulse response functions to reaction time: Rod and cone reaction time data and a computational model

    PubMed Central

    Cao, Dingcai; Zele, Andrew J.; Pokorny, Joel

    2007-01-01

    Reaction times for incremental and decremental stimuli were measured at five suprathreshold contrasts for six retinal illuminance levels where rods alone (0.002–0.2 Trolands), rods and cones (2–20 Trolands) or cones alone (200 Trolands) mediated detection. A 4-primary photostimulator allowed independent control of rod or cone excitations. This is the first report of reaction times to isolated rod or cone stimuli at mesopic light levels under the same adaptation conditions. The main findings are: 1) For rods, responses to decrements were faster than increments, but cone reaction times were closely similar. 2) At light levels where both systems were functional, rod reaction times were ~20 ms longer. The data were fitted with a computational model that incorporates rod and cone impulse response functions and a stimulus-dependent neural sensory component that triggers a motor response. Rod and cone impulse response functions were derived from published psychophysical two-pulse threshold data and temporal modulation transfer functions. The model fits were accomplished with a limited number of free parameters: two global parameters to estimate the irreducible minimum reaction time for each receptor type, and one local parameter for each reaction time versus contrast function. This is the first model to provide a neural basis for the variation in reaction time with retinal illuminance, stimulus contrast, stimulus polarity, and receptor class modulated. PMID:17346763

  1. Acute effects of static and dynamic stretching on hamstrings' response times.

    PubMed

    Ayala, Francisco; De Ste Croix, Mark; Sainz de Baranda, Pilar; Santonja, Fernando

    2014-01-01

    The main purposes of this study were to (a) investigate acute effects of static and dynamic lower limb stretching routines on total response time, pre-motor time and motor time of the medial and lateral hamstrings during maximal eccentric isokinetic knee flexion; and (b) determine whether static and dynamic routines elicit similar responses. A total of 38 active adults completed the following intervention protocols in a randomised order on separate days: (a) non-stretching (control condition), (b) static stretching and (c) dynamic stretching. After the stretching or control intervention, total response time, pre-motor time and motor time of the medial and lateral hamstrings were assessed during eccentric knee flexion movements with participants prone. Measures were compared via a mixed-design factorial ANOVA. There were no main effects for total response time, pre-motor time and motor time. The results suggest that dynamic and static stretching has no influence on hamstrings response times (total response time, pre-motor time and motor time) and hence neither form of stretching reduces this primary risk factor for anterior cruciate ligament injury.

  2. Response Time Analysis and Test of Protection System Instrument Channels for APR1400 and OPR1000

    SciTech Connect

    Lee, Chang Jae; Han, Seung; Yun, Jae Hee; Baek, Seung Min; Lee, Sang Jeong

    2015-07-01

    Safety limits are required to maintain the integrity of physical barriers designed to prevent the uncontrolled release of radioactive materials in nuclear power plants. The safety analysis establishes two critical constraints that include an analytical limit in terms of a measured or calculated variable, and a specific time after the analytical limit is reached to begin protective action. Keeping with the nuclear regulations and industry standards, satisfying these two requirements will ensure that the safety limit will not be exceeded during the design basis event, either an anticipated operational occurrence or a postulated accident. Various studies on the setpoint determination methodology for the safety-related instrumentation have been actively performed to ensure that the requirement of the analytical limit is satisfied. In particular, the protection setpoint methodology for the advanced power reactor 1400 (APP1400) and the optimized power reactor 1000 (OPR1000) has been recently developed to cover both the design basis event and the beyond design basis event. The developed setpoint methodology has also been quantitatively validated using specific computer programs and setpoint calculations. However, the safety of nuclear power plants cannot be fully guaranteed by satisfying the requirement of the analytical limit. In spite of the response time verification requirements of nuclear regulations and industry standards, it is hard to find the studies on the systematically integrated methodology regarding the response time evaluation. In cases of APR1400 and OPR1000, the response time analysis for the plant protection system is partially included in the setpoint calculation and the response time test is separately performed via the specific plant procedure. The test technique has a drawback which is the difficulty to demonstrate completeness of timing test. The analysis technique has also a demerit of resulting in extreme times that not actually possible. Thus

  3. Diagnosis Accuracy of Mean Arterial Pressure Variation during a Lung Recruitment Maneuver to Predict Fluid Responsiveness in Thoracic Surgery with One-Lung Ventilation

    PubMed Central

    Kang, Woon-Seok; Oh, Chung-Sik; Park, Chulmin; Shin, Bo Mi; Yoon, Tae-Gyoon; Rhee, Ka-Young; Woo, Nam-Sik

    2016-01-01

    Background. Lung recruitment maneuver (LRM) during thoracic surgery can reduce systemic venous return and resulting drop in systemic blood pressure depends on the patient's fluid status. We hypothesized that changes in systemic blood pressure during the transition in LRM from one-lung ventilation (OLV) to two-lung ventilation (TLV) may provide an index to predict fluid responsiveness. Methods. Hemodynamic parameters were measured before LRM (T0); after LRM at the time of the lowest mean arterial blood pressure (MAP) (T1) and at 3 minutes (T2); before fluid administration (T3); and 5 minutes after ending it (T4). If the stroke volume index increased by >25% following 10 mL/kg colloid administration for 30 minutes, then the patients were assigned to responder group. Results. Changes in MAP, central venous pressure (CVP), and stroke volume variation (SVV) between T0 and T1 were significantly larger in responders. Areas under the curve for change in MAP, CVP, and SVV were 0.852, 0.759, and 0.820, respectively; the optimal threshold values for distinguishment of responders were 9.5 mmHg, 0.5 mmHg, and 3.5%, respectively. Conclusions. The change in the MAP associated with LRM at the OLV to TLV conversion appears to be a useful indicator of fluid responsiveness after thoracic surgery. Trial Registration. This trial is registered at Clinical Research Information Service with KCT0000774. PMID:27819002

  4. 75 FR 38603 - State Responsibility for the Timely Reporting and Posting of Certain Convictions and...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-02

    ... Federal Motor Carrier Safety Administration State Responsibility for the Timely Reporting and Posting of... part of its responsibility to ensure State compliance with the minimum CDL program standards... SDLA as having responsibility to engage in judicial outreach activities; Ensure that all...

  5. Stable measures of number sense accuracy in math learning disability: Is it time to proceed from basic science to clinical application?

    PubMed

    Júlio-Costa, Annelise; Starling-Alves, Isabella; Lopes-Silva, Júlia Beatriz; Wood, Guilherme; Haase, Vitor Geraldi

    2015-12-01

    Math learning disability (MLD) or developmental dyscalculia is a highly prevalent and persistent difficulty in learning arithmetic that may be explained by different cognitive mechanisms. The accuracy of the number sense has been implicated by some evidence as a core deficit in MLD. However, research on this topic has been mainly conducted in demographically selected samples, using arbitrary cut-off scores to characterize MLD. The clinical relevance of the association between number sense and MLD remains to be investigated. In this study, we aimed at assessing the stability of a number sense accuracy measure (w) across five experimental sessions, in two clinically defined cases of MLD. Stable measures of number sense accuracy estimate are required to clinically characterize subtypes of MLD and to make theoretical inferences regarding the underlying cognitive mechanisms. G. A. was a 10-year-old boy with MLD in the context of dyslexia and phonological processing impairment and his performance remained steadily in the typical scores range. The performance of H. V., a 9-year-old girl with MLD associated with number sense inaccuracy, remained consistently impaired across measurements, with a nonsignificant tendency to worsen. Qualitatively, H. V.'s performance was also characterized by greater variability across sessions. Concomitant clinical observations suggested that H. V.'s difficulties could be aggravated by developing symptoms of mathematics anxiety. Results in these two cases are in line with the hypotheses that at least two reliable patterns of cognitive impairment may underlie math learning difficulties in MLD, one related to number sense inaccuracy and the other to phonological processing impairment. Additionally, it indicates the need for more translational research in order to examine the usefulness and validity of theoretical advances in numerical cognition to the clinical neuropsychological practice with MLD.

  6. Delayed system response times affect immediate physiology and the dynamics of subsequent button press behavior.

    PubMed

    Kohrs, Christin; Hrabal, David; Angenstein, Nicole; Brechmann, André

    2014-11-01

    System response time research is an important issue in human-computer interactions. Experience with technical devices and general rules of human-human interactions determine the user's expectation, and any delay in system response time may lead to immediate physiological, emotional, and behavioral consequences. We investigated such effects on a trial-by-trial basis during a human-computer interaction by measuring changes in skin conductance (SC), heart rate (HR), and the dynamics of button press responses. We found an increase in SC and a deceleration of HR for all three delayed system response times (0.5, 1, 2 s). Moreover, the data on button press dynamics was highly informative since subjects repeated a button press with more force in response to delayed system response times. Furthermore, the button press dynamics could distinguish between correct and incorrect decisions and may thus even be used to infer the uncertainty of a user's decision.

  7. The Simplest Complete Model of Choice Response Time: Linear Ballistic Accumulation

    ERIC Educational Resources Information Center

    Brown, Scott D.; Heathcote, Andrew

    2008-01-01

    We propose a linear ballistic accumulator (LBA) model of decision making and reaction time. The LBA is simpler than other models of choice response time, with independent accumulators that race towards a common response threshold. Activity in the accumulators increases in a linear and deterministic manner. The simplicity of the model allows…

  8. Setting the Response Time Threshold Parameter to Differentiate Solution Behavior from Rapid-Guessing Behavior

    ERIC Educational Resources Information Center

    Kong, Xiaojing J.; Wise, Steven L.; Bhola, Dennison S.

    2007-01-01

    This study compared four methods for setting item response time thresholds to differentiate rapid-guessing behavior from solution behavior. Thresholds were either (a) common for all test items, (b) based on item surface features such as the amount of reading required, (c) based on visually inspecting response time frequency distributions, or (d)…

  9. A Mixture Proportional Hazards Model with Random Effects for Response Times in Tests

    ERIC Educational Resources Information Center

    Ranger, Jochen; Kuhn, Jörg-Tobias

    2016-01-01

    In this article, a new model for test response times is proposed that combines latent class analysis and the proportional hazards model with random effects in a similar vein as the mixture factor model. The model assumes the existence of different latent classes. In each latent class, the response times are distributed according to a…

  10. First passage time: Connecting random walks to functional responses in heterogeneous environments (Invited)

    NASA Astrophysics Data System (ADS)

    Lewis, M. A.; McKenzie, H.; Merrill, E.

    2010-12-01

    In this talk I will outline first passage time analysis for animals undertaking complex movement patterns, and will demonstrate how first passage time can be used to derive functional responses in predator prey systems. The result is a new approach to understanding type III functional responses based on a random walk model. I will extend the analysis to heterogeneous environments to assess the effects of linear features on functional responses in wolves and elk using GPS tracking data.

  11. Emotional Responses during Reading: Physiological Responses Predict Real-Time Reading Comprehension

    ERIC Educational Resources Information Center

    Daley, Samantha G.; Willett, John B.; Fischer, Kurt W.

    2014-01-01

    This study investigated the relationship between emotional responses and reading performance in middle-school students. Although a large number of prior studies have investigated the relationship between emotion and reading, those studies have concentrated primarily on relatively static and distal measures of emotion. In this research, we measured…

  12. Modulation of response timing in ADHD, effects of reinforcement valence and magnitude.

    PubMed

    Luman, Marjolein; Oosterlaan, Jaap; Sergeant, Joseph A

    2008-04-01

    The present study investigated the impact of reinforcement valence and magnitude on response timing in children with ADHD. Children were required to estimate a 1-s interval, and both the median response time (response tendency) and the intrasubject-variability (response stability) were investigated. In addition, heart rate and skin conductance were measured to examine the autonomic responses to reinforcement. Feedback-only trials were compared to low response cost trials (response cost for incorrect responses), low reward trials (reward for correct responses), high response cost and high reward trials. In feedback-only trials, children with ADHD underestimated more severely the interval and responded more variably than controls. Children with ADHD, unlike controls, were unaffected by the reinforcement conditions in terms of time underestimations. The variability of responding, on the other hand, decreased under conditions of reinforcement to a larger extent in children with ADHD than controls. There were no indications that children with ADHD were abnormally affected by the valence or magnitude of reinforcement. Furthermore, skin conductance responses increased when feedback was coupled with reinforcement, an effect which was larger in children with ADHD than controls. This could be interpreted as demonstrating that children with ADHD suffer from a diminished awareness of the significance of feedback in the feedback-only condition. The current study suggests that children with ADHD suffer from motivation problems when reinforcement was not available, at least when variability in responding was measured. Underestimations of time may reflect more stable deficits in ADHD.

  13. Effect of prolonged bedrest and plus Gz acceleration on peripheral visual response time

    NASA Technical Reports Server (NTRS)

    Haines, R. F.

    1973-01-01

    Peripheral visual response time changes during +G sub z acceleration following fourteen days of bedrest are considered as well as what effect prolonged bedrest has upon this response. Eighteen test lights, placed 10 deg are apart along the horizontal meridian of the subject's field of view, were presented in a random sequence. The subject was instructed to press a button as soon as a light appeared. Response time testing occurred periodically during bedrest and continuously during centrifugation testing. The results indicate that: (1) mean response time is significantly longer to stimuli imaged in the far periphery than to stimuli imaged closer to the line of sight; (2) mean response time at each stimulus position tends to be longer at plateau g than during the preacceleration baseline period; (3) mean response time tends to lengthen as the g level is increased; (4) peripheral visual response time during +G sub x acceleration at 2, 3.2, and 3.8 g was not a reliable advanced indicator that blackout was going to occur; and (5) the subject's field of view collapsed rapidly just before blackout. Bedrest data showed that the distribution of response times to stimuli imaged across the subject's horizontal retinal meridian remained remarkably constant from day to day during both the bedrest and recovery periods.

  14. The accuracy with which the 5 times sit-to-stand test, versus gait speed, can identify poor exercise tolerance in patients with COPD

    PubMed Central

    Bernabeu-Mora, Roberto; Medina-Mirapeix, Francesc; Llamazares-Herrán, Eduardo; de Oliveira-Sousa, Silvana Loana; Sánchez-Martinez, Mª Piedad; Escolar-Reina, Pilar

    2016-01-01

    Abstract Identifying those patients who underperform in the 6-minute walk test (6MWT <350 m), and the reasons for their poor performance, is a major concern in the management of chronic obstructive pulmonary disease. To explore the accuracy and relevance of the 4-m gait-speed (4MGS) test, and the 5-repetition sit-to-stand (5STS) test, as diagnostic markers, and clinical determinants, of poor performance in the 6MWT. We recruited 137 patients with stable chronic obstructive pulmonary disease to participate in our cross-sectional study. Patients completed the 4MGS and 5STS tests, with quantitative (in seconds) and qualitative ordinal data collected; the latter were categorized using a scale of 0 to 4. The following potential covariates and clinical determinants of poor 6MWT were collated: age, quadriceps muscle-strength (QMS), health status, dyspnea, depression, and airflow limitation. Area under the receiver-operating characteristic curve data (AUC) was used to assess accuracy, with logistic regression used to explore relevance as clinical determinants. The AUCs generated using the 4MGS and 5STS tests were comparable, at 0.719 (95% confidence interval [CI] 0.629–0.809) and 0.711 (95% CI 0.613–0.809), respectively. With ordinal data, the 5STS test was most accurate (AUC of 0.732; 95% CI 0.645–0.819); the 4MGS test showed poor discriminatory power (AUC <0.7), although accuracy improved (0.726, 95% CI 0.637–0.816) when covariates were included. Unlike the 4MGS test, the 5STS test provided a significant clinical determinant of a poor 6MWT (odds ratio 1.23, 95% CI 1.05–1.44). The 5STS test reliably predicts a poor 6MWT, especially when using ordinal data. Used alone, the 4MGS test is reliable when measured with continuous data. PMID:27583918

  15. Psychophysics in a Web browser? Comparing response times collected with JavaScript and Psychophysics Toolbox in a visual search task.

    PubMed

    de Leeuw, Joshua R; Motz, Benjamin A

    2016-03-01

    Behavioral researchers are increasingly using Web-based software such as JavaScript to conduct response time experiments. Although there has been some research on the accuracy and reliability of response time measurements collected using JavaScript, it remains unclear how well this method performs relative to standard laboratory software in psychologically relevant experimental manipulations. Here we present results from a visual search experiment in which we measured response time distributions with both Psychophysics Toolbox (PTB) and JavaScript. We developed a methodology that allowed us to simultaneously run the visual search experiment with both systems, interleaving trials between two independent computers, thus minimizing the effects of factors other than the experimental software. The response times measured by JavaScript were approximately 25 ms longer than those measured by PTB. However, we found no reliable difference in the variability of the distributions related to the software, and both software packages were equally sensitive to changes in the response times as a result of the experimental manipulations. We concluded that JavaScript is a suitable tool for measuring response times in behavioral research.

  16. Stability of adaptive cruise control systems taking account of vehicle response time and delay

    NASA Astrophysics Data System (ADS)

    Davis, L. C.

    2012-08-01

    The region of string stability of a platoon of adaptive cruise control vehicles, taking into account the delay and response of the vehicle powertrain, is found. An upper bound on the explicit delay time as a function the first-order powertrain response time constant is determined. The system is characterized by a headway time constant, a sensitivity parameter, relative (to the vehicle immediately in front) velocity control, and delayed-velocity feedback or acceleration feedback.

  17. What does more time buy you? Another look at the effects of long-term residence on production accuracy of English /inverted r/ and /l/ by Japanese speakers.

    PubMed

    Larson-Hall, Jenifer

    2006-01-01

    This study tested the issue of whether extended length of residence (LOR) in adulthood can provide sufficient input to overcome age effects. The study replicates Flege, Takagi, and Mann (1995), which found that 10 out of 12 Japanese learners of English with extensive residence (12 years or more) produced liquids as accurately as native speakers of English (NS). Further, for both accuracy and native-like accentedness, the Japanese with extensive residence performed statistically better as a group than inexperienced Japanese (less than 3 years of residence). Results with a new sample of Japanese learners in this study found no statistical difference between the Japanese groups with extended versus short LOR although both reported equal levels of daily input in English. Additionally, both groups received statistically lower scores than NS. Moreover, LOR affected the two groups differently: The accuracy and native-like accentedness of words and sentences by Japanese with extensive residence declined with LOR (and chronological age when age of arrival was partialled out), while for Japanese with short residence accent improved with increased LOR (but not age). This study is the first to document a decline in second language production ability with LOR and age in older second language learners. However, this finding deserves to be addressed with further research, as the study was not designed to investigate this question and thus not all relevant factors, such as motivation or attitude, were controlled for. The results from the short-residence learners indicate that the initial one to two years of immersion may be the most important for improving phonological ability.

  18. Taking time to feel our body: Steady increases in heartbeat perception accuracy and decreases in alexithymia over 9 months of contemplative mental training.

    PubMed

    Bornemann, Boris; Singer, Tania

    2017-03-01

    The ability to accurately perceive signals from the body has been shown to be important for physical and psychological health as well as understanding one's emotions. Despite the importance of this skill, often indexed by heartbeat perception accuracy (HBPa), little is known about its malleability. Here, we investigated whether contemplative mental practice can increase HBPa. In the context of a 9-month mental training study, the ReSource Project, two matched cohorts (n = 77 and n = 79) underwent three training modules of 3 months' duration that targeted attentional and interoceptive abilities (Presence module), socio-affective (Affect module), and socio-cognitive (Perspective module) abilities. A third cohort (n = 78) underwent 3 months of practice (Affect module) and a retest control group (n = 84) did not undergo any training. HBPa was measured with a heartbeat tracking task before and after each training module. Emotional awareness was measured by the Toronto Alexithymia Scale (TAS). Participants with TAS scores > 60 at screening were excluded. HBPa was found to increase steadily over the training, with significant and small- to medium-sized effects emerging after 6 months (Cohen's d = .173) and 9 months (d = .273) of mental training. Changes in HBPa were concomitant with and predictive of changes in emotional awareness. Our results suggest that HBPa can indeed be trained through intensive contemplative practice. The effect takes longer than the 8 weeks of typical mindfulness courses to reach meaningful magnitude. These increments in interoceptive accuracy and the related improvements in emotional awareness point to opportunities for improving physical and psychological health through contemplative mental training.

  19. The Largest Response Component in the Motor Cortex Reflects Movement Timing but Not Movement Type

    PubMed Central

    Sussillo, David; Ryu, Stephen I.

    2016-01-01

    Abstract Neural activity in monkey motor cortex (M1) and dorsal premotor cortex (PMd) can reflect a chosen movement well before that movement begins. The pattern of neural activity then changes profoundly just before movement onset. We considered the prediction, derived from formal considerations, that the transition from preparation to movement might be accompanied by a large overall change in the neural state that reflects when movement is made rather than which movement is made. Specifically, we examined “components” of the population response: time-varying patterns of activity from which each neuron’s response is approximately composed. Amid the response complexity of individual M1 and PMd neurons, we identified robust response components that were “condition-invariant”: their magnitude and time course were nearly identical regardless of reach direction or path. These condition-invariant response components occupied dimensions orthogonal to those occupied by the “tuned” response components. The largest condition-invariant component was much larger than any of the tuned components; i.e., it explained more of the structure in individual-neuron responses. This condition-invariant response component underwent a rapid change before movement onset. The timing of that change predicted most of the trial-by-trial variance in reaction time. Thus, although individual M1 and PMd neurons essentially always reflected which movement was made, the largest component of the population response reflected movement timing rather than movement type. PMID:27761519

  20. [A study for time-history waveform synthesis of algorithm in shock response spectrum (SRS)].

    PubMed

    Liu, Hong-ying; Ma, Ai-jun

    2002-12-01

    Objective. To present an effective on-line SRS time-history waveform synthesis method for simulating pyrotechnic shock environment with electrodynamic shakers. Method. A procedure was developed for synthesizing a SRS time-history waveform according to a general principle. The effect of three main parameters to waveform's shape, amplitude of acceleration and duration were investigated. A modification method of SRS's amplitude and an optimal algorithm of time-history waveform were presented. Result. The algorithm was used to generate a time-history waveform that could satisfy SRS's accuracy requirement and electrodynamic shaker's acceleration limitation. Conclusion. The numerical example indicates that the developed method is effective. The synthesized time-history waveform can be used to simulate pyrotechnic shock environment using electrodynamic shakers.

  1. Detector response in time-of-flight mass spectrometry at high pulse repetition frequencies

    NASA Technical Reports Server (NTRS)

    Gulcicek, Erol E.; Boyle, James G.

    1993-01-01

    Dead time effects in chevron configured dual microchannel plates (MCPs) are investigated. Response times are determined experimentally for one chevron-configured dual MCP-type detector and two discrete dynode-type electron multipliers with 16 and 23 resistively divided stages. All of these detectors are found to be suitable for time-of-flight mass spectrometry (TOF MS), yielding 3-6-ns (FWHM) response times triggered on a single ion pulse. It is concluded that, unless there are viable solutions to overcome dead time disadvantages for continuous dynode detectors, suitable discrete dynode detectors for TOF MS appear to have a significant advantage for high repetition rate operation.

  2. Estimating Testing Time: The Effects of Item Characteristics on Response Latency.

    ERIC Educational Resources Information Center

    Halkitis, Perry N.; And Others

    The relationship between test item characteristics and testing time was studied for a computer-administered licensing examination. One objective of the study was to develop a model to predict testing time on the basis of known item characteristics. Response latencies (i.e., the amount of time taken by examinees to read, review, and answer items)…

  3. Design and testing of magnetorheological valve with fast force response time and great dynamic force range

    NASA Astrophysics Data System (ADS)

    Kubík, M.; Macháček, O.; Strecker, Z.; Roupec, J.; Mazůrek, I.

    2017-04-01

    The paper deals with design, simulation and experimental testing of a magnetorheological (MR) valve with short response time. The short response time is achieved by a suitable design of an active zone in combination with use of a ferrite material for magnetic circuit. The magneto-static model and the simplified hydraulic model of the MR valve are examined and experimentally verified. The development the MR valve achieves an average response time 4.1 ms and the maximum dynamic force range of eight.

  4. Acquisition of decision making criteria: Reward rate ultimately beats accuracy

    PubMed Central

    Balci, Fuat; Simen, Patrick; Niyogi, Ritwik; Saxe, Andrew; Hughes, Jessica A.; Holmes, Philip; Cohen, Jonathan D.

    2012-01-01

    Speed-accuracy tradeoffs strongly influence the rate of reward that can be earned in many decision-making tasks. Previous reports suggest that human participants often adopt suboptimal speed-accuracy tradeoffs in single session, two-alternative forced-choice tasks. We investigated whether humans acquired optimal speed-accuracy tradeoffs when extensively trained with multiple signal qualities. When performance was characterized in terms of decision time and accuracy, our participants eventually performed nearly optimally in the case of higher signal qualities. Rather than adopting decision criteria that were individually optimal for each signal quality, participants adopted a single threshold that was nearly optimal for most signal qualities. However, setting a single threshold for different coherence conditions resulted in only negligible decrements in the maximum possible reward rate. Finally, we tested two hypotheses regarding the possible sources of suboptimal performance: a) favoring accuracy over reward rate and b) misestimating the reward rate due to timing uncertainty. Our findings provide support for both hypotheses, but also for the hypothesis that participants can learn to approach optimality. We find specifically that an accuracy bias dominates early performance, but diminishes greatly with practice. The residual discrepancy between optimal and observed performance can be explained by an adaptive response to uncertainty in time estimation. PMID:21264716

  5. Voice reaction times with recognition for Commodore computers

    NASA Technical Reports Server (NTRS)

    Washburn, David A.; Putney, R. Thompson

    1990-01-01

    Hardware and software modifications are presented that allow for collection and recognition by a Commodore computer of spoken responses. Responses are timed with millisecond accuracy and automatically analyzed and scored. Accuracy data for this device from several experiments are presented. Potential applications and suggestions for improving recognition accuracy are also discussed.

  6. Neural time and movement time in choice of whistle or pulse burst responses to different auditory stimuli by dolphins.

    PubMed

    Ridgway, Sam H

    2011-02-01

    Echolocating dolphins emit trains of clicks and receive echoes from ocean targets. They often emit each successive ranging click about 20 ms after arrival of the target echo. In echolocation, decisions must be made about the target--fish or fowl, predator or food. In the first test of dolphin auditory decision speed, three bottlenose dolphins (Tursiops truncatus) chose whistle or pulse burst responses to different auditory stimuli randomly presented without warning in rapid succession under computer control. The animals were trained to hold pressure catheters in the nasal cavity so that pressure increases required for sound production could be used to split response time (RT) into neural time and movement time. Mean RT in the youngest and fastest dolphin ranged from 175 to 213 ms when responding to tones and from 213 to 275 ms responding to pulse trains. The fastest neural times and movement times were around 60 ms. The results suggest that echolocating dolphins tune to a rhythm so that succeeding pulses in a train are produced about 20 ms over target round-trip travel time. The dolphin nervous system has evolved for rapid processing of acoustic stimuli to accommodate for the more rapid sound speed in water compared to air.

  7. Response preparation and intra-individual reaction time variability in schizophrenia.

    PubMed

    Denisas, Dankinas; Sigita, Mėlynytė; Aldona, Šiurkutė; Kastytis, Dapšys

    2016-01-01

    Background. It is important to prepare response in advance to increase the efficiency of its execution. The process of response preparation is usually studied using the precueing paradigm. In this paradigm subjects have to employ the preceding information about further imperative stimulus to perform proper response preparation, which shortens the reaction time of subsequent response execution. Previous studies detected the impairment of response preparation in schizophrenia only with the help of electroencephalographic parameters, but not with the assessing of reaction time. Therefore, in this study we attempted to find a behavioural parameter that could detect impairment in response preparation of schizophrenia patients. It was recently found that appropriate response preparation not only shortens the reaction time but also increases its stability, which is measured with the intra-individual reaction time variability. It was also revealed that response stability could better find cognitive dysfunction in some studies of schizophrenia disorder than classical behavioural parameters. Hence, the main goal of this study was to verify if intra-individual reaction time variability could detect the impairment of response preparation in schizophrenia patients. Materials and methods. In order to achieve the main purpose, we carried out a study with 14 schizophrenia patients and 14 control group subjects. We used precueing paradigm in our research, in which participants had to employ information about stimulus probability for the proper response preparation. Results. Our main result showed that despite the responses of schizophrenia patients were faster to the high-probability stimulus than to the low-probability one (F (1, 13) = 30.9, p < 0.001), intra-individual reaction time variability did not differ in this group between the responses to more and less probable stimuli (F (1, 13) = 0.64, p = 0.44). Conclusions. Results of the study suggest that people with schizophrenia

  8. Response preparation and intra-individual reaction time variability in schizophrenia

    PubMed Central

    Denisas, Dankinas; Sigita, Mėlynytė; Aldona, Šiurkutė; Kastytis, Dapšys

    2016-01-01

    Background. It is important to prepare response in advance to increase the efficiency of its execution. The process of response preparation is usually studied using the precueing paradigm. In this paradigm subjects have to employ the preceding information about further imperative stimulus to perform proper response preparation, which shortens the reaction time of subsequent response execution. Previous studies detected the impairment of response preparation in schizophrenia only with the help of electroencephalographic parameters, but not with the assessing of reaction time. Therefore, in this study we attempted to find a behavioural parameter that could detect impairment in response preparation of schizophrenia patients. It was recently found that appropriate response preparation not only shortens the reaction time but also increases its stability, which is measured with the intra-individual reaction time variability. It was also revealed that response stability could better find cognitive dysfunction in some studies of schizophrenia disorder than classical behavioural parameters. Hence, the main goal of this study was to verify if intra-individual reaction time variability could detect the impairment of response preparation in schizophrenia patients. Materials and methods. In order to achieve the main purpose, we carried out a study with 14 schizophrenia patients and 14 control group subjects. We used precueing paradigm in our research, in which participants had to employ information about stimulus probability for the proper response preparation. Results. Our main result showed that despite the responses of schizophrenia patients were faster to the high-probability stimulus than to the low-probability one (F (1, 13) = 30.9, p < 0.001), intra-individual reaction time variability did not differ in this group between the responses to more and less probable stimuli (F (1, 13) = 0.64, p = 0.44). Conclusions. Results of the study suggest that people with schizophrenia

  9. Response of Vibrio fischeri to repeated exposures over time in an Online Toxicity Monitor

    EPA Science Inventory

    Online Toxicity Monitors have been developed to provide continuous, time-relevant information regarding water quality. These systems measure a physiological or behavioral response of a sentinel organism to changes water quality. One such system, the Microlan Toxcontrol, is base...

  10. Optimizing the response time of Ni-based resistive temperature detectors

    NASA Astrophysics Data System (ADS)

    Kim, Deok Su; Choi, Kyo Sang; Yang, Hee Jun; Ryu, Min Soo; Chae, Ji Sung; Chang, Sung Pil

    2015-04-01

    Resistive temperature detectors (RTDs) are widely used to monitor and control the temperature of work environments due to their higher sensitivity, excellent reliability and stability, and very linear output signal compared to other types of temperature detectors. However, RTDs have some shortcomings, including a slow response time. A nickel-based RTDs were designed, fabricated, and characterized in order to achieve faster response times. We used micromachining processes to analyze devices with different resistor thicknesses, distances between resistor lines, and resistor line widths. The response times of the RTDs were measured to be between 7.5104 and 23.4583 s. From these measurement data, we can conclude that thinner RTDs with larger surface areas show improved response times.

  11. 75 FR 79961 - Temporary Suspension of Certain Oil Spill Response Time Requirements To Support Deepwater Horizon...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-21

    ...; 2050-AG63 Temporary Suspension of Certain Oil Spill Response Time Requirements To Support Deepwater Horizon Oil Spill of National Significance (SONS) Response AGENCIES: Coast Guard, DHS, and Environmental... discharge of crude oil into the Gulf of Mexico, which was thereafter declared a ``Spill of...

  12. Research on Mail Surveys: Response Rates and Methods in Relation to Population Group and Time.

    ERIC Educational Resources Information Center

    Boser, Judith A.; Green, Kathy

    The purpose of this review was to look for trends across time in response rates and variables studied for published mail surveys and to compare response rates and variables studied for different target populations. Studies were identified in databases in four fields: education, psychology, business and marketing, and sociology. A total of 225…

  13. Time and flow-direction responses of shear-styress-sensitive liquid crystal coatings

    NASA Technical Reports Server (NTRS)

    Reda, Daniel C.; Muraqtore, J. J.; Heinick, James T.

    1994-01-01

    Time and flow-direction responses of shear-stress liquid crystal coatings were exploresd experimentally. For the time-response experiments, coatings were exposed to transient, compressible flows created during the startup and off-design operation of an injector-driven supersonic wind tunnel. Flow transients were visualized with a focusing schlieren system and recorded with a 100 frame/s color video camera.

  14. Effect of Time of Day on Performance, Hormonal and Metabolic Response during a 1000-M Cycling Time Trial

    PubMed Central

    Fernandes, Alan Lins; Lopes-Silva, João Paulo; Bertuzzi, Rômulo; Casarini, Dulce Elena; Arita, Danielle Yuri; Bishop, David John; Lima-Silva, Adriano Eduardo

    2014-01-01

    The aim of this study was to determine the effect of time of day on performance, pacing, and hormonal and metabolic responses during a 1000-m cycling time-trial. Nine male, recreational cyclists visited the laboratory four times. During the 1st visit the participants performed an incremental test and during the 2nd visit they performed a 1000-m cycling familiarization trial. On the 3rd and 4th visits, the participants performed a 1000-m TT at either 8 am or 6 pm, in randomized, repeated-measures, crossover design. The time to complete the time trial was lower in the evening than in the morning (88.2±8.7 versus 94.7±10.9 s, respectively, p<0.05), but there was no significant different in pacing. However, oxygen uptake and aerobic mechanical power output at 600 and 1000 m tended to be higher in the evening (p<0.07 and 0.09, respectively). There was also a main effect of time of day for insulin, cortisol, and total and free testosterone concentration, which were all higher in the morning (+60%, +26%, +31% and +22%, respectively, p<0.05). The growth hormone, was twofold higher in the evening (p<0.05). The plasma glucose was ∼11% lower in the morning (p<0.05). Glucagon, norepinephrine, epinephrine and lactate were similar for the morning and evening trials (p>0.05), but the norepinephrine response to the exercise was increased in the morning (+46%, p<0.05), and it was accompanied by a 5-fold increase in the response of glucose. Muscle recruitment, as measured by electromyography, was similar between morning and evening trials (p>0.05). Our findings suggest that performance was improved in the evening, and it was accompanied by an improved hormonal and metabolic milieu. PMID:25289885

  15. Modeling the Climate Responses to Spectral Solar Variability on Decadal and Centennial Time Scales

    NASA Astrophysics Data System (ADS)

    Cahalan, Robert; Wen, Guoyong; Pilewskie, Peter; Harder, Jerald

    We apply two scenarios of external forcing, namely the SIM-based out-of-phase variations and the proxy-based in-phase variations, as input to a time-dependent radiative-convective model (RCM), and also to the GISS modelE GCM, to compute climate responses to solar variation on decadal time scale. We find that the maximum temperature response occurs in the upper stratosphere, while temperature response decreases downward to the surface for both scenarios, and both models. The upper stratospheric temperature peak-to-peak responses to out-of-phase solar forcing are 0.6 K in RCM and 0.9 K over the tropical region in GCM simulations, a factor of 5 times as large as responses to in-phase solar forcing. Stratospheric responses are in-phase with TSI (Total Solar Irradiance) variations. The modeled upper stratospheric temperature responses to the SORCE SIM observed SSI (Spectral Solar Irradiance) forcing are similar to the HALOE (Halogen Occultation Experiment) observed 11-year temperature variations. Surface responses to the two SSI scenarios are small for both RCM and GCM studies, as compared to the stratospheric responses. Though solar irradiance variations on centennial time scale are not well known, the two sce-narios of reconstructed TSI time series (i.e., the one based on 11-year cycle with background [Lean 2000] and the other one from flux transport that has much less background component [Wang, Lean, and Sheeley, 2005]) provide potential range of variations of TSI on centennial time scale. We apply phase relations among different spectral irradiance bands both from SIM observation and proxy reconstructions to the two scenarios of historical TSI to derive the as-sociated historical SSI. The historical SSI is used to drive the RCM. The updated atmosphere and ocean mixed coupled RCM including diffusion to deep-ocean will provide the first order estimate of temperature response to SSI variation on centennial time scales. We anticipate the stratosphere, troposphere, and

  16. Evidence for separate neural mechanisms for the timing of discrete and sustained responses.

    PubMed

    Gooch, Cynthia M; Wiener, Martin; Portugal, George S; Matell, Matthew S

    2007-07-02

    Methamphetamine (MAP), an indirect dopamine agonist, has been shown to produce a leftward shift in the time of responding under operant response protocols that encourage repetitive responding (e.g., lever pressing). Given the involvement of striatal dopamine activity in the control of discrete motor behavior, as well as in the timing of these responses, an important question arises as to whether a dissociation is possible between changes in the timing of discrete responding and timing of other behaviors. Rats were trained on a modified peak-interval (PI) procedure such that reward was contingent upon the presence of the animal's snout in a nosepoke apparatus at the target time, as an alternative to the typical requirement of a discrete head entry response. Thus spatial selection, but not necessarily motor behavior, at the appropriate time was required to receive a reward. Rats were given MAP in one of 3 doses (0.5, 1.0, or 1.5 mg/kg), or a saline control injection before PI sessions to determine whether the drug elicits a dose-dependent effect on timing of spatial position, as it has been shown to do for discrete behaviors. Following administration of MAP, the peak time of the proportion of time spent in the nosepoke did not change, while the peak time of the rate of response shifted to the left. Single-trial analysis revealed a similar pattern: Position of response step functions defined by being in the nosepoke did not shift, but step functions based on response rate changed with increasing doses of MAP. These data support a model of multiple timing processes controlling different behaviors, at least one of which is specific to discrete motor behavior and is modifiable by dopamine.

  17. Design PID controllers for desired time-domain or frequency-domain response.

    PubMed

    Zhang, Weidong; Xi, Yugeng; Yang, Genke; Xu, Xiaoming

    2002-10-01

    Practical requirements on the design of control systems, especially process control systems, are usually specified in terms of time-domain response, such as overshoot and rise time, or frequency-domain response, such as resonance peak and stability margin. Although numerous methods have been developed for the design of the proportional-integral-derivative (PID) controller, little work has been done in relation to the quantitative time-domain and frequency-domain responses. In this paper, we study the following problem: Given a nominal stable process with time delay, we design a suboptimal PID controller to achieve the required time-domain response or frequency-domain response for the nominal system or the uncertain system. An H(infinity) PID controller is developed based on optimal control theory and the parameters are derived analytically. Its properties are investigated and compared with that of two developed suboptimal controllers: an H2 PID controller and a Maclaurin PID controller. It is shown that all three controllers can provide the quantitative time-domain and frequency-domain responses.

  18. A window on perception: Response times of odontocete cetaceans in audiometric tests

    NASA Astrophysics Data System (ADS)

    Blackwood, Diane J.; Ridgway, Sam H.; Evans, William E.

    2002-05-01

    A standard psychometric measurement is response time, the interval elapsing between a stimulus and a response. While studies of response time have been published for humans and other terrestrial mammals, this study marks the first report of response times for odontocete cetaceans at threshold in an audiometric task. Two white whales (Delphinapterus leucas) and four Atlantic bottlenose dolphins (Tursiops truncatus) were given audiometric tests to determine masked hearing thresholds. Animals were tested at 26 frequencies over a range from 200 Hz to 100 kHz using pure tones. The test tone amplitudes covered a range of 20 dB re 1 microPascal including the hearing threshold of the animal at that frequency. Hearing thresholds varied from 87.5 dB to 125.5 dB depending on frequency, masking noise intensity and individual animal. Data was analyzed to determine characteristic relationships between response time and amplitude of test tone for each frequency and animal. The two whales responded significantly slower (640 ms, 0.001) than the four dolphins (430 ms). As in terrestrial animals, reaction time became shorter as stimulus strength increased. At threshold, median response time across frequencies within each animal varied about 150 ms.

  19. Response to gravity by Zea mays seedlings. I. Time course of the response

    NASA Technical Reports Server (NTRS)

    Bandurski, R. S.; Schulze, A.; Dayanandan, P.; Kaufman, P. B.

    1984-01-01

    Gravistimulation induces an asymmetric distribution of free indole-3-acetic acid (IAA) in the cortex-epidermis of the Zea mays L. cv 'Stowells Evergreen' mesocotyl within 15 minutes, the shortest time tested. IAA was measured by an isotope dilution method as the pentaflurobenzyl ester. The per cent IAA in the lower half of the mescotyl cortex was 56 to 57% at 15, 30, and 90 minutes after stimulus initiation. Curvature is detectable in the mescotyl within 3 minutes after beginning gravitropic stimulation. The rate of curvature of the mesocotyl increases during the first 60 minutes to maximum of about 30 degrees per hour. Thus, the growth asymmetry continues to increase for 45 minutes after hormone asymmetry is established. Free IAA occurs predominantly in the stele of the mesocotyl whereas esterified IAA is mainly in the mesocotyl cortex-epidermis. This compartmentation may permit determining in which tissue the hormone asymmetry arises. Current data suggest the asymmetry originated in the stele.

  20. Relevance of intracellular polarity to accuracy of eukaryotic chemotaxis

    NASA Astrophysics Data System (ADS)

    Hiraiwa, Tetsuya; Nagamatsu, Akihiro; Akuzawa, Naohiro; Nishikawa, Masatoshi; Shibata, Tatsuo

    2014-10-01

    Eukaryotic chemotaxis is usually mediated by intracellular signals that tend to localize at the front or back of the cell. Such intracellular polarities frequently require no extracellular guidance cues, indicating that spontaneous polarization occurs in the signal network. Spontaneous polarization activity is considered relevant to the persistent motions in random cell migrations and chemotaxis. In this study, we propose a theoretical model that connects spontaneous intracellular polarity and motile ability in a chemoattractant solution. We demonstrate that the intracellular polarity can enhance the accuracy of chemotaxis. Chemotactic accuracy should also depend on chemoattractant concentration through the concentration-dependent correlation time in the polarity direction. Both the polarity correlation time and the chemotactic accuracy depend on the degree of responsiveness to the chemical gradient. We show that optimally accurate chemotaxis occurs at an intermediate responsiveness of intracellular polarity. Experimentally, we find that the persistence time of randomly migrating Dictyostelium cells depends on the chemoattractant concentration, as predicted by our theory. At the optimum responsiveness, this ameboid cell can enhance its chemotactic accuracy tenfold.

  1. Relevance of intracellular polarity to accuracy of eukaryotic chemotaxis.

    PubMed

    Hiraiwa, Tetsuya; Nagamatsu, Akihiro; Akuzawa, Naohiro; Nishikawa, Masatoshi; Shibata, Tatsuo

    2014-08-14

    Eukaryotic chemotaxis is usually mediated by intracellular signals that tend to localize at the front or back of the cell. Such intracellular polarities frequently require no extracellular guidance cues, indicating that spontaneous polarization occurs in the signal network. Spontaneous polarization activity is considered relevant to the persistent motions in random cell migrations and chemotaxis. In this study, we propose a theoretical model that connects spontaneous intracellular polarity and motile ability in a chemoattractant solution. We demonstrate that the intracellular polarity can enhance the accuracy of chemotaxis. Chemotactic accuracy should also depend on chemoattractant concentration through the concentration-dependent correlation time in the polarity direction. Both the polarity correlation time and the chemotactic accuracy depend on the degree of responsiveness to the chemical gradient. We show that optimally accurate chemotaxis occurs at an intermediate responsiveness of intracellular polarity. Experimentally, we find that the persistence time of randomly migrating Dictyostelium cells depends on the chemoattractant concentration, as predicted by our theory. At the optimum responsiveness, this ameboid cell can enhance its chemotactic accuracy tenfold.

  2. Aeroelastic response of an aircraft wing with mounted engine subjected to time-dependent thrust

    NASA Astrophysics Data System (ADS)

    Mazidi, A.; Kalantari, H.; Fazelzadeh, S. A.

    2013-05-01

    In this paper, the aeroelastic response of a wing containing an engine subjected to different types of time-dependent thrust excitations is presented. In order to precisely consider the spanwise and chordwise locations of the engine and the time-dependent follower force in governing equations, derived through Lagrange's method, the generalized function theory is used. Unsteady aerodynamic lift and moment in the time domain are considered in terms of Wagner's function. Numerical simulations of the aeroelastic response to different types of time-dependent thrust excitation and comparisons with the previously published results are supplied. Effects of the engine mass and location and also the type of time-dependent thrust on the wing aeroelastic response are studied and pertinent conclusions are outlined.

  3. The effect of loading time on flexible pavement dynamic response: a finite element analysis

    NASA Astrophysics Data System (ADS)

    Yin, Hao; Solaimanian, Mansour; Kumar, Tanmay; Stoffels, Shelley

    2007-12-01

    Dynamic response of asphalt concrete (AC) pavements under moving load is a key component for accurate prediction of flexible pavement performance. The time and temperature dependency of AC materials calls for utilizing advanced material characterization and mechanistic theories, such as viscoelasticity and stress/strain analysis. In layered elastic analysis, as implemented in the new Mechanistic-Empirical Pavement Design Guide (MEPDG), the time dependency is accounted for by calculating the loading times at different AC layer depths. In this study, the time effect on pavement response was evaluated by means of the concept of “pseudo temperature.” With the pavement temperature measured from instrumented thermocouples, the time and temperature dependency of AC materials was integrated into one single factor, termed “effective temperature.” Via this effective temperature, pavement responses under a transient load were predicted through finite element analysis. In the finite element model, viscoelastic behavior of AC materials was characterized through relaxation moduli, while the layers with unbound granular material were assumed to be in an elastic mode. The analysis was conducted for two different AC mixtures in a simplified flexible pavement structure at two different seasons. Finite element analysis results reveal that the loading time has a more pronounced impact on pavement response in the summer for both asphalt types. The results indicate that for reasonable prediction of dynamic response in flexible pavements, the effect of the depth-dependent loading time on pavement temperature should be considered.

  4. Preserved emotional modulation of motor response time despite psychomotor slowing in young-old adults.

    PubMed

    Hälbig, Thomas D; Creighton, Judy; Assuras, Stephanie; Borod, Joan C; Tse, Winona; Gracies, Jean-Michel; Foldi, Nancy S; Kaufmann, Horacio; Olanow, C Warren; Voustianiouk, Andrei

    2011-08-01

    Whereas aging affects cognitive and psychomotor processes negatively, the impact of aging on emotional processing is less clear. Using an "old-new" binary decision task, we ascertained the modulation of response latencies after presentation of neutral and emotional pictures in "young" (M = 27.1 years) and "young-old" adults with a mean age below 60 (M = 57.7 years). Stimuli varied on valence (pleasant, neutral, and unpleasant) and arousal (high and low) dimensions. Young-old adults had significantly longer reaction times. However, young and young-old adults showed the exact same pattern of response time modulation by emotional stimuli: Response latencies were longer for high-arousal than for low-arousal pictures and longer for negative than for positive or neutral stimuli. This result suggests that the specific effects of implicitly processed emotional valence and arousal information on behavioral response time are preserved in young-old adults despite significant age-related psychomotor decline.

  5. Use of the Vocera Communications Badge Improves Public Safety Response Times

    PubMed Central

    Joslin, Jeremy D.; Goldberger, David; Johnson, Loretta; Waltz, D. Paul

    2016-01-01

    Objectives. Violence in the Emergency Department (ED) has been a long-standing issue complicated by deficiencies in staff training, ease of weapons access, and response availability of public safety officers. The Vocera Badge is being used by our staff to request public safety assistance in lieu of a formal phone call to the University Police Communications Center. We sought to learn if use of this technology improved officer response times to the ED. Methods. Mean response times were reviewed and descriptive statistics analyzed to determine if the use of the Vocera Badge improved public safety officer response times to the ED. Results. Average response times improved from an average of 3.2 minutes (SD = 0.456) in the 6 months before the use of the communication badges to an average of 1.02 minutes (SD = 0.319) in the 6 months after use began. Conclusions. The use of the Vocera Badge seemed to decrease response times of public safety officers to our ED compared with the traditional method of calling a dispatch center to request assistance. PMID:27127654

  6. Time Work by Overworked Professionals: Strategies in Response to the Stress of Higher Status

    PubMed Central

    Moen, Phyllis; Lam, Jack; Ammons, Samantha; Kelly, Erin L.

    2013-01-01

    How are professionals responding to the time strains brought on by the stress of their higher status jobs? Qualitative data from professionals reveal (a) general acceptance of the emerging temporal organization of professional work, including rising time demands and blurred boundaries around work/ nonwork times and places, and (b) time work as strategic responses to work intensification, overloads, and boundarylessness. We detected four time-work strategies: prioritizing time, scaling back obligations, blocking out time, and time shifting of obligations. These strategies are often more work-friendly than family-friendly, but “blocking out time” and “time shifting” suggest promising avenues for work-time policy and practice. PMID:24039337

  7. Changes in the Social Responsibility Attitudes of Engineering Students Over Time.

    PubMed

    Bielefeldt, Angela R; Canney, Nathan E

    2016-10-01

    This research explored how engineering student views of their responsibility toward helping individuals and society through their profession, so-called social responsibility, change over time. A survey instrument was administered to students initially primarily in their first year, senior year, or graduate studies majoring in mechanical, civil, or environmental engineering at five institutions in September 2012, April 2013, and March 2014. The majority of the students (57 %) did not change significantly in their social responsibility attitudes, but 23 % decreased and 20 % increased. The students who increased, decreased, or remained the same in their social responsibility attitudes over time did not differ significantly in terms of gender, academic rank, or major. Some differences were found between institutions. Students who decreased in social responsibility initially possessed more positive social responsibility attitudes, were less likely to indicate that college courses impacted their views of social responsibility, and were more likely to have decreased in the frequency that they participated in volunteer activities, compared to students who did not change or increased their social responsibility. Although the large percentage of engineering students who decreased their social responsibility during college was disappointing, it is encouraging that courses and participation in volunteer activities may combat this trend.

  8. Reticence, Accuracy and Efficacy

    NASA Astrophysics Data System (ADS)

    Oreskes, N.; Lewandowsky, S.

    2015-12-01

    James Hansen has cautioned the scientific community against "reticence," by which he means a reluctance to speak in public about the threat of climate change. This may contribute to social inaction, with the result that society fails to respond appropriately to threats that are well understood scientifically. Against this, others have warned against the dangers of "crying wolf," suggesting that reticence protects scientific credibility. We argue that both these positions are missing an important point: that reticence is not only a matter of style but also of substance. In previous work, Bysse et al. (2013) showed that scientific projections of key indicators of climate change have been skewed towards the low end of actual events, suggesting a bias in scientific work. More recently, we have shown that scientific efforts to be responsive to contrarian challenges have led scientists to adopt the terminology of a "pause" or "hiatus" in climate warming, despite the lack of evidence to support such a conclusion (Lewandowsky et al., 2015a. 2015b). In the former case, scientific conservatism has led to under-estimation of climate related changes. In the latter case, the use of misleading terminology has perpetuated scientific misunderstanding and hindered effective communication. Scientific communication should embody two equally important goals: 1) accuracy in communicating scientific information and 2) efficacy in expressing what that information means. Scientists should strive to be neither conservative nor adventurous but to be accurate, and to communicate that accurate information effectively.

  9. 5 CFR 2424.25 - Response of the exclusive representative; purpose; time limits; content; severance; service.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...; purpose; time limits; content; severance; service. 2424.25 Section 2424.25 Administrative Personnel... § 2424.25 Response of the exclusive representative; purpose; time limits; content; severance; service. (a... management rights, including permissive subjects under 5 U.S.C. 7106(b)(1), and procedures and...

  10. 5 CFR 2424.25 - Response of the exclusive representative; purpose; time limits; content; severance; service.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...; purpose; time limits; content; severance; service. 2424.25 Section 2424.25 Administrative Personnel... § 2424.25 Response of the exclusive representative; purpose; time limits; content; severance; service. (a... management rights, including permissive subjects under 5 U.S.C. 7106(b)(1), and procedures and...

  11. Cortisol Response to Physical Activity in African American Toddlers Attending Full-Time Day Care

    ERIC Educational Resources Information Center

    Wall, Sarah J.; Rudisill, Mary E.; Gladden, L. Bruce

    2009-01-01

    The purpose of this study was to examine African American toddlers' cortisol response to acute physical play activity within a full-time subsidized day care environment. Saliva samples were taken from participants (N = 22, ages 26-45.5 months) before and after physical play and control play conditions at the same time of day. Actiheart[TM]monitors…

  12. Response Time as an Indicator of Test Taker Speed: Assumptions Meet Reality

    ERIC Educational Resources Information Center

    Wise, Steven L.

    2015-01-01

    The growing presence of computer-based testing has brought with it the capability to routinely capture the time that test takers spend on individual test items. This, in turn, has led to an increased interest in potential applications of response time in measuring intellectual ability and achievement. Goldhammer (this issue) provides a very useful…

  13. Anxiety and Sensory Over-Responsivity in Toddlers with Autism Spectrum Disorders: Bidirectional Effects across Time

    ERIC Educational Resources Information Center

    Green, Shulamite A.; Ben-Sasson, Ayelet; Soto, Timothy W.; Carter, Alice S.

    2012-01-01

    This report focuses on the emergence of and bidirectional effects between anxiety and sensory over-responsivity (SOR) in toddlers with autism spectrum disorders (ASD). Participants were 149 toddlers with ASD and their mothers, assessed at 2 annual time points. A cross-lag analysis showed that anxiety symptoms increased over time while SOR remained…

  14. Modeling Individual Differences in Numerical Reasoning Speed as a Random Effect of Response Time Limits

    ERIC Educational Resources Information Center

    Semmes, Robert; Davison, Mark L.; Close, Catherine

    2011-01-01

    If numerical reasoning items are administered under time limits, will two dimensions be required to account for the responses, a numerical ability dimension and a speed dimension? A total of 182 college students answered 74 numerical reasoning items. Every item was taken with and without time limits by half the students. Three psychometric models…

  15. Study and response time for the visual recognition of 'similarity' and identity

    NASA Technical Reports Server (NTRS)

    Derks, P. L.; Bauer, T. M.

    1974-01-01

    Four subjects compared successively presented pairs of line patterns for a match between any lines in the pattern (similarity) and for a match between all lines (identity). The encoding or study times for pattern recognition from immediate memory and the latency in responses to comparison stimuli were examined. Qualitative differences within and between subjects were most evident in study times.

  16. Inclusion, Education, and Avoidance: The Prime Time Response to September 11.

    ERIC Educational Resources Information Center

    Gladstone-Sovell, Tracey; Wilkerson, William R.

    This paper is an initial examination of prime time television's response to the events of September 11, 2001. Based on a review of the 2001-2002 television season's prime time programs, the study identifies 15 programs (out of 65 that ran the entire season) that incorporated September 11th elements. Themes of these programs are discussed as are…

  17. Relating Cerebellar Purkinje Cell Activity to the Timing and Amplitude of Conditioned Eyelid Responses

    PubMed Central

    Khilkevich, Andrei; Mauk, Michael D.

    2015-01-01

    How Purkinje cell (PC) activity may be altered by learning is central to theories of the cerebellum. Pavlovian eyelid conditioning, because of how directly it engages the cerebellum, has helped reveal many aspects of cerebellar learning and the underlying mechanisms. Theories of cerebellar learning assert that climbing fiber inputs control plasticity at synapses onto PCs, and thus PCs control the expression of learned responses. We tested this assertion by recording 184 eyelid PCs and 240 non-eyelid PCs during the expression of conditioned eyelid responses (CRs) in well trained rabbits. By contrasting the responses of eyelid and non-eyelid PCs and by contrasting the responses of eyelid PCs under conditions that produce differently timed CRs, we test the hypothesis that learning-related changes in eyelid PCs contribute to the learning and adaptive timing of the CRs. We used a variety of analyses to test the quantitative relationships between eyelid PC responses and the kinematic properties of the eyelid CRs. We find that the timing of eyelid PC responses varies systematically with the timing of the behavioral CRs and that there are differences in the magnitude of eyelid PC responses between larger-CR, smaller-CR, and non-CR trials. However, eyelid PC activity does not encode any single kinematic property of the behavioral CRs at a fixed time lag, nor does it linearly encode CR amplitude. Even so, the results are consistent with the hypothesis that learning-dependent changes in PC activity contribute to the adaptively timed expression of conditioned eyelid responses. PMID:25995469

  18. Pulse Shape and Timing Dependence on the Spike-Timing Dependent Plasticity Response of Ion-Conducting Memristors as Synapses

    PubMed Central

    Campbell, Kristy A.; Drake, Kolton T.; Barney Smith, Elisa H.

    2016-01-01

    Ion-conducting memristors comprised of the layered materials Ge2Se3/SnSe/Ag are promising candidates for neuromorphic computing applications. Here, the spike-timing dependent plasticity (STDP) application is demonstrated for the first time with a single memristor type operating as a synapse over a timescale of 10 orders of magnitude, from nanoseconds through seconds. This large dynamic range allows the memristors to be useful in applications that require slow biological times, as well as fast times such as needed in neuromorphic computing, thus allowing multiple functions in one design for one memristor type—a “one size fits all” approach. This work also investigated the effects of varying the spike pulse shapes on the STDP response of the memristors. These results showed that small changes in the pre- and postsynaptic pulse shape can have a significant impact on the STDP. These results may provide circuit designers with insights into how pulse shape affects the actual memristor STDP response and aid them in the design of neuromorphic circuits and systems that can take advantage of certain features in the memristor STDP response that are programmable via the pre- and postsynaptic pulse shapes. In addition, the energy requirement per memristor is approximated based on the pulse shape and timing responses. The energy requirement estimated per memristor operating on slower biological timescales (milliseconds to seconds) is larger (nanojoules range), as expected, than the faster (nanoseconds) operating times (~0.1 pJ in some cases). Lastly, the memristors responded in a similar manner under normal STDP conditions (pre- and post-spikes applied to opposite memristor terminals) as they did to the case where a waveform corresponding to the difference between pre- and post-spikes was applied to only one electrode, with the other electrode held at ground potential. By applying the difference signal to only one terminal, testing of the memristor in various

  19. Improved time response for polymer fibre Bragg grating based humidity sensors

    NASA Astrophysics Data System (ADS)

    Zhang, W.; Webb, D. J.; Peng, G.-D.

    2011-05-01

    In this work we experimentally investigate the response time of humidity sensors based on polymer optical fibre (POF) Bragg gratings. By the use of etching with acetone we can control the diameter of POF based on poly (methyl methacrylate) in order to reduce the diffusion time of water into the polymer and hence speed up the relative wavelength change caused by humidity variations. A much improved response time of 11 minutes has been achieved by using a POF FBG with a reduced diameter of 135 microns.

  20. Dynamic response time of a metal foam magneto-rheological damper

    NASA Astrophysics Data System (ADS)

    Yan, Yao X.; Hui, Liu X.; M, Yu; J, Fu; Dong, Liao H.

    2013-02-01

    Magneto-rheological (MR) dampers are a promising type of semi-active control device for various dynamic systems. Recently, low-cost MR dampers without any sealing structure have been required. Motivated by the desire to overcome the need for the costly dynamic seals of conventional MR dampers, a new type of metal foam MR damper is proposed in this study and the dynamic response performance is also investigated. The metal foam is firmly adhered to a working cylinder to store the unexcited MR fluids. In the action of a magnetic field, MR fluids will be extracted from the metal foam and fill up the shear gap to produce the MR effect. Three time parameters related to response time are introduced to further describe the dynamic response process. The results show that, due to the period required for extracting the MR fluids out from the metal foam, the time to produce the damper force of the metal foam MR damper is longer than for conventional fluid-filled MR dampers. The response time of the metal foam MR damper will change with different currents and shear rates. Given a constant shear rate, in a small range of currents (0-1.5 A), the response time decreases rapidly as the operating current increases; however, there is a slower change rate in larger ranges. To evaluate the effect of shear rate on response time, shear rates ranging from 2 to 10 s-1 are tested, and the results demonstrate that with increasing shear rates the response time decreases.