Sample records for accuracy response time

  1. 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…

  2. Response moderation models for conditional dependence between response time and response accuracy.

    PubMed

    Bolsinova, Maria; Tijmstra, Jesper; Molenaar, Dylan

    2017-05-01

    It is becoming more feasible and common to register response times in the application of psychometric tests. Researchers thus have the opportunity to jointly model response accuracy and response time, which provides users with more relevant information. The most common choice is to use the hierarchical model (van der Linden, 2007, Psychometrika, 72, 287), which assumes conditional independence between response time and accuracy, given a person's speed and ability. However, this assumption may be violated in practice if, for example, persons vary their speed or differ in their response strategies, leading to conditional dependence between response time and accuracy and confounding measurement. We propose six nested hierarchical models for response time and accuracy that allow for conditional dependence, and discuss their relationship to existing models. Unlike existing approaches, the proposed hierarchical models allow for various forms of conditional dependence in the model and allow the effect of continuous residual response time on response accuracy to be item-specific, person-specific, or both. Estimation procedures for the models are proposed, as well as two information criteria that can be used for model selection. Parameter recovery and usefulness of the information criteria are investigated using simulation, indicating that the procedure works well and is likely to select the appropriate model. Two empirical applications are discussed to illustrate the different types of conditional dependence that may occur in practice and how these can be captured using the proposed hierarchical models. © 2016 The British Psychological Society.

  3. Distinguishing Fast and Slow Processes in Accuracy - Response Time Data

    PubMed Central

    Coomans, Frederik; Hofman, Abe; Brinkhuis, Matthieu; van der Maas, Han L. J.; Maris, Gunter

    2016-01-01

    We investigate the relation between speed and accuracy within problem solving in its simplest non-trivial form. We consider tests with only two items and code the item responses in two binary variables: one indicating the response accuracy, and one indicating the response speed. Despite being a very basic setup, it enables us to study item pairs stemming from a broad range of domains such as basic arithmetic, first language learning, intelligence-related problems, and chess, with large numbers of observations for every pair of problems under consideration. We carry out a survey over a large number of such item pairs and compare three types of psychometric accuracy-response time models present in the literature: two ‘one-process’ models, the first of which models accuracy and response time as conditionally independent and the second of which models accuracy and response time as conditionally dependent, and a ‘two-process’ model which models accuracy contingent on response time. We find that the data clearly violates the restrictions imposed by both one-process models and requires additional complexity which is parsimoniously provided by the two-process model. We supplement our survey with an analysis of the erroneous responses for an example item pair and demonstrate that there are very significant differences between the types of errors in fast and slow responses. PMID:27167518

  4. Distinguishing Fast and Slow Processes in Accuracy - Response Time Data.

    PubMed

    Coomans, Frederik; Hofman, Abe; Brinkhuis, Matthieu; van der Maas, Han L J; Maris, Gunter

    2016-01-01

    We investigate the relation between speed and accuracy within problem solving in its simplest non-trivial form. We consider tests with only two items and code the item responses in two binary variables: one indicating the response accuracy, and one indicating the response speed. Despite being a very basic setup, it enables us to study item pairs stemming from a broad range of domains such as basic arithmetic, first language learning, intelligence-related problems, and chess, with large numbers of observations for every pair of problems under consideration. We carry out a survey over a large number of such item pairs and compare three types of psychometric accuracy-response time models present in the literature: two 'one-process' models, the first of which models accuracy and response time as conditionally independent and the second of which models accuracy and response time as conditionally dependent, and a 'two-process' model which models accuracy contingent on response time. We find that the data clearly violates the restrictions imposed by both one-process models and requires additional complexity which is parsimoniously provided by the two-process model. We supplement our survey with an analysis of the erroneous responses for an example item pair and demonstrate that there are very significant differences between the types of errors in fast and slow responses.

  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. Evaluating perceptual integration: uniting response-time- and accuracy-based methodologies.

    PubMed

    Eidels, Ami; Townsend, James T; Hughes, Howard C; Perry, Lacey A

    2015-02-01

    This investigation brings together a response-time system identification methodology (e.g., Townsend & Wenger Psychonomic Bulletin & Review 11, 391-418, 2004a) and an accuracy methodology, intended to assess models of integration across stimulus dimensions (features, modalities, etc.) that were proposed by Shaw and colleagues (e.g., Mulligan & Shaw Perception & Psychophysics 28, 471-478, 1980). The goal was to theoretically examine these separate strategies and to apply them conjointly to the same set of participants. The empirical phases were carried out within an extension of an established experimental design called the double factorial paradigm (e.g., Townsend & Nozawa Journal of Mathematical Psychology 39, 321-359, 1995). That paradigm, based on response times, permits assessments of architecture (parallel vs. serial processing), stopping rule (exhaustive vs. minimum time), and workload capacity, all within the same blocks of trials. The paradigm introduced by Shaw and colleagues uses a statistic formally analogous to that of the double factorial paradigm, but based on accuracy rather than response times. We demonstrate that the accuracy measure cannot discriminate between parallel and serial processing. Nonetheless, the class of models supported by the accuracy data possesses a suitable interpretation within the same set of models supported by the response-time data. The supported model, consistent across individuals, is parallel and has limited capacity, with the participants employing the appropriate stopping rule for the experimental setting.

  7. 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.

  8. Modeling Individual Differences in Response Time and Accuracy in Numeracy

    PubMed Central

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

    2015-01-01

    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

  9. 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.

  10. The effect of stimulus intensity on response time and accuracy in dynamic, temporally constrained environments.

    PubMed

    Causer, J; McRobert, A P; Williams, A M

    2013-10-01

    The ability to make accurate judgments and execute effective skilled movements under severe temporal constraints are fundamental to elite performance in a number of domains including sport, military combat, law enforcement, and medicine. In two experiments, we examine the effect of stimulus strength on response time and accuracy in a temporally constrained, real-world, decision-making task. Specifically, we examine the effect of low stimulus intensity (black) and high stimulus intensity (sequin) uniform designs, worn by teammates, to determine the effect of stimulus strength on the ability of soccer players to make rapid and accurate responses. In both field- and laboratory-based scenarios, professional soccer players viewed developing patterns of play and were required to make a penetrative pass to an attacking player. Significant differences in response accuracy between uniform designs were reported in laboratory- and field-based experiments. Response accuracy was significantly higher in the sequin compared with the black uniform condition. Response times only differed between uniform designs in the laboratory-based experiment. These findings extend the literature into a real-world environment and have significant implications for the design of clothing wear in a number of domains. © 2012 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  11. Accuracy of three-dimensional seismic ground response analysis in time domain using nonlinear numerical simulations

    NASA Astrophysics Data System (ADS)

    Liang, Fayun; Chen, Haibing; Huang, Maosong

    2017-07-01

    To provide appropriate uses of nonlinear ground response analysis for engineering practice, a three-dimensional soil column with a distributed mass system and a time domain numerical analysis were implemented on the OpenSees simulation platform. The standard mesh of a three-dimensional soil column was suggested to be satisfied with the specified maximum frequency. The layered soil column was divided into multiple sub-soils with a different viscous damping matrix according to the shear velocities as the soil properties were significantly different. It was necessary to use a combination of other one-dimensional or three-dimensional nonlinear seismic ground analysis programs to confirm the applicability of nonlinear seismic ground motion response analysis procedures in soft soil or for strong earthquakes. The accuracy of the three-dimensional soil column finite element method was verified by dynamic centrifuge model testing under different peak accelerations of the earthquake. As a result, nonlinear seismic ground motion response analysis procedures were improved in this study. The accuracy and efficiency of the three-dimensional seismic ground response analysis can be adapted to the requirements of engineering practice.

  12. 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

  13. Assessing nonchoosers' eyewitness identification accuracy from photographic showups by using confidence and response times.

    PubMed

    Sauerland, Melanie; Sagana, Anna; Sporer, Siegfried L

    2012-10-01

    While recent research has shown that the accuracy of positive identification decisions can be assessed via confidence and decision times, gauging lineup rejections has been less successful. The current study focused on 2 different aspects which are inherent in lineup rejections. First, we hypothesized that decision times and confidence ratings should be postdictive of identification rejections if they refer to a single lineup member only. Second, we hypothesized that dividing nonchoosers according to the reasons they provided for their decisions can serve as a useful postdictor for nonchoosers' accuracy. To test these assumptions, we used (1) 1-person lineups (showups) in order to obtain confidence and response time measures referring to a single lineup member, and (2) asked nonchoosers about their reasons for making a rejection. Three hundred and eighty-four participants were asked to identify 2 different persons after watching 1 of 2 stimulus films. The results supported our hypotheses. Nonchoosers' postdecision confidence ratings were well-calibrated. Likewise, we successfully established optimum time and confidence boundaries for nonchoosers. Finally, combinations of postdictors increased the number of accurate classifications compared with individual postdictors. PsycINFO Database Record (c) 2012 APA, all rights reserved.

  14. 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.

  15. Enhanced Photoacoustic Gas Analyser Response Time and Impact on Accuracy at Fast Ventilation Rates during Multiple Breath Washout

    PubMed Central

    Horsley, Alex; Macleod, Kenneth; Gupta, Ruchi; Goddard, Nick; Bell, Nicholas

    2014-01-01

    Background The Innocor device contains a highly sensitive photoacoustic gas analyser that has been used to perform multiple breath washout (MBW) measurements using very low concentrations of the tracer gas SF6. Use in smaller subjects has been restricted by the requirement for a gas analyser response time of <100 ms, in order to ensure accurate estimation of lung volumes at rapid ventilation rates. Methods A series of previously reported and novel enhancements were made to the gas analyser to produce a clinically practical system with a reduced response time. An enhanced lung model system, capable of delivering highly accurate ventilation rates and volumes, was used to assess in vitro accuracy of functional residual capacity (FRC) volume calculation and the effects of flow and gas signal alignment on this. Results 10–90% rise time was reduced from 154 to 88 ms. In an adult/child lung model, accuracy of volume calculation was −0.9 to 2.9% for all measurements, including those with ventilation rate of 30/min and FRC of 0.5 L; for the un-enhanced system, accuracy deteriorated at higher ventilation rates and smaller FRC. In a separate smaller lung model (ventilation rate 60/min, FRC 250 ml, tidal volume 100 ml), mean accuracy of FRC measurement for the enhanced system was minus 0.95% (range −3.8 to 2.0%). Error sensitivity to flow and gas signal alignment was increased by ventilation rate, smaller FRC and slower analyser response time. Conclusion The Innocor analyser can be enhanced to reliably generate highly accurate FRC measurements down at volumes as low as those simulating infant lung settings. Signal alignment is a critical factor. With these enhancements, the Innocor analyser exceeds key technical component recommendations for MBW apparatus. PMID:24892522

  16. 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.

  17. Knowing where is different from knowing what: Distinct response time profiles and accuracy effects for target location, orientation, and color probability.

    PubMed

    Jabar, Syaheed B; Filipowicz, Alex; Anderson, Britt

    2017-11-01

    When a location is cued, targets appearing at that location are detected more quickly. When a target feature is cued, targets bearing that feature are detected more quickly. These attentional cueing effects are only superficially similar. More detailed analyses find distinct temporal and accuracy profiles for the two different types of cues. This pattern parallels work with probability manipulations, where both feature and spatial probability are known to affect detection accuracy and reaction times. However, little has been done by way of comparing these effects. Are probability manipulations on space and features distinct? In a series of five experiments, we systematically varied spatial probability and feature probability along two dimensions (orientation or color). In addition, we decomposed response times into initiation and movement components. Targets appearing at the probable location were reported more quickly and more accurately regardless of whether the report was based on orientation or color. On the other hand, when either color probability or orientation probability was manipulated, response time and accuracy improvements were specific for that probable feature dimension. Decomposition of the response time benefits demonstrated that spatial probability only affected initiation times, whereas manipulations of feature probability affected both initiation and movement times. As detection was made more difficult, the two effects further diverged, with spatial probability disproportionally affecting initiation times and feature probability disproportionately affecting accuracy. In conclusion, all manipulations of probability, whether spatial or featural, affect detection. However, only feature probability affects perceptual precision, and precision effects are specific to the probable attribute.

  18. Normative accuracy and response time data for the computerized Benton Facial Recognition Test (BFRT-c).

    PubMed

    Rossion, Bruno; Michel, Caroline

    2018-03-16

    We report normative data from a large (N = 307) sample of young adult participants tested with a computerized version of the long form of the classical Benton Facial Recognition Test (BFRT; Benton & Van Allen, 1968). The BFRT-c requires participants to match a target face photograph to either one or three of six face photographs presented simultaneously. We found that the percent accuracy on the BFRT-c (81%-83%) was below ceiling yet well above chance level, with little interindividual variance in this typical population sample, two important aspects of a sensitive clinical test. Although the split-half reliability on response accuracy was relatively low, due to the large variability in difficulty across items, the correct response times measured in this version-completed in 3 min, on average-provide a reliable and critical complementary measure of performance at individual unfamiliar-face matching. In line with previous observations from other measures, females outperformed male participants at the BFRT-c, especially for female faces. In general, performance was also lower following lighting changes than following head rotations, in line with previous studies that have emphasized participants' limited ability to match pictures of unfamiliar faces with important variations in illumination. Overall, this normative data set supports the validity of the BFRT-c as a key component of a battery of tests to identify clinical impairments in individual face recognition, such as observed in acquired prosopagnosia. However, this analysis strongly recommends that researchers consider the full test results: Beyond global indexes of performance based on accuracy rates only, they should consider the time taken to match individual faces as well as the variability in performance across items.

  19. 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

  20. 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…

  1. 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.

  2. A sequential sampling account of response bias and speed-accuracy tradeoffs in a conflict detection task.

    PubMed

    Vuckovic, Anita; Kwantes, Peter J; Humphreys, Michael; Neal, Andrew

    2014-03-01

    Signal Detection Theory (SDT; Green & Swets, 1966) is a popular tool for understanding decision making. However, it does not account for the time taken to make a decision, nor why response bias might change over time. Sequential sampling models provide a way of accounting for speed-accuracy trade-offs and response bias shifts. In this study, we test the validity of a sequential sampling model of conflict detection in a simulated air traffic control task by assessing whether two of its key parameters respond to experimental manipulations in a theoretically consistent way. Through experimental instructions, we manipulated participants' response bias and the relative speed or accuracy of their responses. The sequential sampling model was able to replicate the trends in the conflict responses as well as response time across all conditions. Consistent with our predictions, manipulating response bias was associated primarily with changes in the model's Criterion parameter, whereas manipulating speed-accuracy instructions was associated with changes in the Threshold parameter. The success of the model in replicating the human data suggests we can use the parameters of the model to gain an insight into the underlying response bias and speed-accuracy preferences common to dynamic decision-making tasks. © 2013 American Psychological Association

  3. 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…

  4. 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.

  5. Getting more from accuracy and response time data: methods for fitting the linear ballistic accumulator.

    PubMed

    Donkin, Chris; Averell, Lee; Brown, Scott; Heathcote, Andrew

    2009-11-01

    Cognitive models of the decision process provide greater insight into response time and accuracy than do standard ANOVA techniques. However, such models can be mathematically and computationally difficult to apply. We provide instructions and computer code for three methods for estimating the parameters of the linear ballistic accumulator (LBA), a new and computationally tractable model of decisions between two or more choices. These methods-a Microsoft Excel worksheet, scripts for the statistical program R, and code for implementation of the LBA into the Bayesian sampling software WinBUGS-vary in their flexibility and user accessibility. We also provide scripts in R that produce a graphical summary of the data and model predictions. In a simulation study, we explored the effect of sample size on parameter recovery for each method. The materials discussed in this article may be downloaded as a supplement from http://brm.psychonomic-journals.org/content/supplemental.

  6. 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.

  7. 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.

  8. 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…

  9. Reaction time and accuracy in individuals with aphasia during auditory vigilance tasks.

    PubMed

    Laures, Jacqueline S

    2005-11-01

    Research indicates that attentional deficits exist in aphasic individuals. However, relatively little is known about auditory vigilance performance in individuals with aphasia. The current study explores reaction time (RT) and accuracy in 10 aphasic participants and 10 nonbrain-damaged controls during linguistic and nonlinguistic auditory vigilance tasks. Findings indicate that the aphasic group was less accurate during both tasks than the control group, but was not slower in their accurate responses. Further examination of the data revealed variability in the aphasic participants' RT contributing to the lower accuracy scores.

  10. Inhibitory Performance, Response Speed, Intraindividual Variability, and Response Accuracy in ADHD

    ERIC Educational Resources Information Center

    De Zeeuw, Patrick; Aarnoudse-Moens, Cornelieke; Bijlhout, Joyce; Konig, Claudia; Uiterweer, Annebeth Post; Papanikolau, Alky; Hoogenraad, Caecilia; Imandt, Lieke; De Been, Debbie; Sergeant, Joseph A.; Oosterlaan, Jaap

    2008-01-01

    The study aims to investigate the influence of inhibitory performance, response speed, intraindividual variability and response accuracy in distinguishing children from those with Attention-deficit/Hyperactivity (ADHD) syndrome from normal healthy children. The results conclude that there exist large number of differences in the symptoms between…

  11. A simple and sensitive method to measure timing accuracy.

    PubMed

    De Clercq, Armand; Crombez, Geert; Buysse, Ann; Roeyers, Herbert

    2003-02-01

    Timing accuracy in presenting experimental stimuli (visual information on a PC or on a TV) and responding (keyboard presses and mouse signals) is of importance in several experimental paradigms. In this article, a simple system for measuring timing accuracy is described. The system uses two PCs (at least Pentium II, 200 MHz), a photocell, and an amplifier. No additional boards and timing hardware are needed. The first PC, a SlavePC, monitors the keyboard presses or mouse signals from the PC under test and uses a photocell that is placed in front of the screen to detect the appearance of visual stimuli on the display. The software consists of a small program running on the SlavePC. The SlavePC is connected through a serial line with a second PC. This MasterPC controls the SlavePC through an ActiveX control, which is used in a Visual Basic program. The accuracy of our system was investigated by using a similar setup of a SlavePC and a MasterPC to generate pulses and by using a pulse generator card. These tests revealed that our system has a 0.01-msec accuracy. As an illustration, the reaction time accuracy of INQUISIT for a few applications was tested using our system. It was found that in those applications that we investigated, INQUISIT measures reaction times from keyboard presses with millisecond accuracy.

  12. 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…

  13. The Effects of Spatial Stimulus-Response Compatibility on Choice Time Production Accuracy and Variability

    ERIC Educational Resources Information Center

    Rakitin, Brian C.

    2005-01-01

    Five experiments examined the relations between timing and attention using a choice time production task in which the latency of a spatial choice response is matched to a target interval (3 or 5 s). Experiments 1 and 2 indicated that spatial stimulus-response incompatibility increased nonscalar timing variability without affecting timing accuracy…

  14. COMPASS time synchronization and dissemination—Toward centimetre positioning accuracy

    NASA Astrophysics Data System (ADS)

    Wang, ZhengBo; Zhao, Lu; Wang, ShiGuang; Zhang, JianWei; Wang, Bo; Wang, LiJun

    2014-09-01

    In this paper we investigate methods to achieve highly accurate time synchronization among the satellites of the COMPASS global navigation satellite system (GNSS). Owing to the special design of COMPASS which implements several geo-stationary satellites (GEO), time synchronization can be highly accurate via microwave links between ground stations to the GEO satellites. Serving as space-borne relay stations, the GEO satellites can further disseminate time and frequency signals to other satellites such as the inclined geo-synchronous (IGSO) and mid-earth orbit (MEO) satellites within the system. It is shown that, because of the accuracy in clock synchronization, the theoretical accuracy of COMPASS positioning and navigation will surpass that of the GPS. In addition, the COMPASS system can function with its entire positioning, navigation, and time-dissemination services even without the ground link, thus making it much more robust and secure. We further show that time dissemination using the COMPASS-GEO satellites to earth-fixed stations can achieve very high accuracy, to reach 100 ps in time dissemination and 3 cm in positioning accuracy, respectively. In this paper, we also analyze two feasible synchronization plans. All special and general relativistic effects related to COMPASS clocks frequency and time shifts are given. We conclude that COMPASS can reach centimeter-level positioning accuracy and discuss potential applications.

  15. Interval Timing Accuracy and Scalar Timing in C57BL/6 Mice

    PubMed Central

    Buhusi, Catalin V.; Aziz, Dyana; Winslow, David; Carter, Rickey E.; Swearingen, Joshua E.; Buhusi, Mona C.

    2010-01-01

    In many species, interval timing behavior is accurate—appropriate estimated durations—and scalar—errors vary linearly with estimated durations. While accuracy has been previously examined, scalar timing has not been yet clearly demonstrated in house mice (Mus musculus), raising concerns about mouse models of human disease. We estimated timing accuracy and precision in C57BL/6 mice, the most used background strain for genetic models of human disease, in a peak-interval procedure with multiple intervals. Both when timing two intervals (Experiment 1) or three intervals (Experiment 2), C57BL/6 mice demonstrated varying degrees of timing accuracy. Importantly, both at individual and group level, their precision varied linearly with the subjective estimated duration. Further evidence for scalar timing was obtained using an intraclass correlation statistic. This is the first report of consistent, reliable scalar timing in a sizable sample of house mice, thus validating the PI procedure as a valuable technique, the intraclass correlation statistic as a powerful test of the scalar property, and the C57BL/6 strain as a suitable background for behavioral investigations of genetically engineered mice modeling disorders of interval timing. PMID:19824777

  16. 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…

  17. 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.

  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. Including Both Time and Accuracy in Defining Text Search Efficiency.

    ERIC Educational Resources Information Center

    Symons, Sonya; Specht, Jacqueline A.

    1994-01-01

    Examines factors related to efficiency in a textbook search task. Finds that time and accuracy involved distinct processes and that accuracy was related to verbal competence. Finds further that measures of planning and extracting information accounted for 59% of the variance in search efficiency. Suggests that both accuracy and rate need to be…

  20. Real-Time Tropospheric Product Establishment and Accuracy Assessment in China

    NASA Astrophysics Data System (ADS)

    Chen, M.; Guo, J.; Wu, J.; Song, W.; Zhang, D.

    2018-04-01

    Tropospheric delay has always been an important issue in Global Navigation Satellite System (GNSS) processing. Empirical tropospheric delay models are difficult to simulate complex and volatile atmospheric environments, resulting in poor accuracy of the empirical model and difficulty in meeting precise positioning demand. In recent years, some scholars proposed to establish real-time tropospheric product by using real-time or near-real-time GNSS observations in a small region, and achieved some good results. This paper uses real-time observing data of 210 Chinese national GNSS reference stations to estimate the tropospheric delay, and establishes ZWD grid model in the country wide. In order to analyze the influence of tropospheric grid product on wide-area real-time PPP, this paper compares the method of taking ZWD grid product as a constraint with the model correction method. The results show that the ZWD grid product estimated based on the national reference stations can improve PPP accuracy and convergence speed. The accuracy in the north (N), east (E) and up (U) direction increase by 31.8 %,15.6 % and 38.3 %, respectively. As with the convergence speed, the accuracy of U direction experiences the most improvement.

  1. Remote real-time monitoring of free flaps via smartphone photography and 3G wireless Internet: a prospective study evidencing diagnostic accuracy.

    PubMed

    Engel, Holger; Huang, Jung Ju; Tsao, Chung Kan; Lin, Chia-Yu; Chou, Pan-Yu; Brey, Eric M; Henry, Steven L; Cheng, Ming Huei

    2011-11-01

    This prospective study was designed to compare the accuracy rate between remote smartphone photographic assessments and in-person examinations for free flap monitoring. One hundred and three consecutive free flaps were monitored with in-person examinations and assessed remotely by three surgeons (Team A) via photographs transmitted over smartphone. Four other surgeons used the traditional in-person examinations as Team B. The response time to re-exploration was defined as the interval between when a flap was evaluated as compromised by the nurse/house officer and when the decision was made for re-exploration. The accuracy rate was 98.7% and 94.2% for in-person and smartphone photographic assessments, respectively. The response time of 8 ± 3 min in Team A was statistically shorter than the 180 ± 104 min in Team B (P = 0.01 by the Mann-Whitney test). The remote smartphone photography assessment has a comparable accuracy rate and shorter response time compared with in-person examination for free flap monitoring. Copyright © 2011 Wiley Periodicals, Inc.

  2. Improvement on Timing Accuracy of LIDAR for Remote Sensing

    NASA Astrophysics Data System (ADS)

    Zhou, G.; Huang, W.; Zhou, X.; Huang, Y.; He, C.; Li, X.; Zhang, L.

    2018-05-01

    The traditional timing discrimination technique for laser rangefinding in remote sensing, which is lower in measurement performance and also has a larger error, has been unable to meet the high precision measurement and high definition lidar image. To solve this problem, an improvement of timing accuracy based on the improved leading-edge timing discrimination (LED) is proposed. Firstly, the method enables the corresponding timing point of the same threshold to move forward with the multiple amplifying of the received signal. Then, timing information is sampled, and fitted the timing points through algorithms in MATLAB software. Finally, the minimum timing error is calculated by the fitting function. Thereby, the timing error of the received signal from the lidar is compressed and the lidar data quality is improved. Experiments show that timing error can be significantly reduced by the multiple amplifying of the received signal and the algorithm of fitting the parameters, and a timing accuracy of 4.63 ps is achieved.

  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. © The Author(s) 2016.

  4. Person-Fit Statistics for Joint Models for Accuracy and Speed

    ERIC Educational Resources Information Center

    Fox, Jean-Paul; Marianti, Sukaesi

    2017-01-01

    Response accuracy and response time data can be analyzed with a joint model to measure ability and speed of working, while accounting for relationships between item and person characteristics. In this study, person-fit statistics are proposed for joint models to detect aberrant response accuracy and/or response time patterns. The person-fit tests…

  5. 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

  6. The effect of stimulus strength on the speed and accuracy of a perceptual decision.

    PubMed

    Palmer, John; Huk, Alexander C; Shadlen, Michael N

    2005-05-02

    Both the speed and the accuracy of a perceptual judgment depend on the strength of the sensory stimulation. When stimulus strength is high, accuracy is high and response time is fast; when stimulus strength is low, accuracy is low and response time is slow. Although the psychometric function is well established as a tool for analyzing the relationship between accuracy and stimulus strength, the corresponding chronometric function for the relationship between response time and stimulus strength has not received as much consideration. In this article, we describe a theory of perceptual decision making based on a diffusion model. In it, a decision is based on the additive accumulation of sensory evidence over time to a bound. Combined with simple scaling assumptions, the proportional-rate and power-rate diffusion models predict simple analytic expressions for both the chronometric and psychometric functions. In a series of psychophysical experiments, we show that this theory accounts for response time and accuracy as a function of both stimulus strength and speed-accuracy instructions. In particular, the results demonstrate a close coupling between response time and accuracy. The theory is also shown to subsume the predictions of Piéron's Law, a power function dependence of response time on stimulus strength. The theory's analytic chronometric function allows one to extend theories of accuracy to response time.

  7. A comparison of item response models for accuracy and speed of item responses with applications to adaptive testing.

    PubMed

    van Rijn, Peter W; Ali, Usama S

    2017-05-01

    We compare three modelling frameworks for accuracy and speed of item responses in the context of adaptive testing. The first framework is based on modelling scores that result from a scoring rule that incorporates both accuracy and speed. The second framework is the hierarchical modelling approach developed by van der Linden (2007, Psychometrika, 72, 287) in which a regular item response model is specified for accuracy and a log-normal model for speed. The third framework is the diffusion framework in which the response is assumed to be the result of a Wiener process. Although the three frameworks differ in the relation between accuracy and speed, one commonality is that the marginal model for accuracy can be simplified to the two-parameter logistic model. We discuss both conditional and marginal estimation of model parameters. Models from all three frameworks were fitted to data from a mathematics and spelling test. Furthermore, we applied a linear and adaptive testing mode to the data off-line in order to determine differences between modelling frameworks. It was found that a model from the scoring rule framework outperformed a hierarchical model in terms of model-based reliability, but the results were mixed with respect to correlations with external measures. © 2017 The British Psychological Society.

  8. Efficiency and Accuracy of Time-Accurate Turbulent Navier-Stokes Computations

    NASA Technical Reports Server (NTRS)

    Rumsey, Christopher L.; Sanetrik, Mark D.; Biedron, Robert T.; Melson, N. Duane; Parlette, Edward B.

    1995-01-01

    The accuracy and efficiency of two types of subiterations in both explicit and implicit Navier-Stokes codes are explored for unsteady laminar circular-cylinder flow and unsteady turbulent flow over an 18-percent-thick circular-arc (biconvex) airfoil. Grid and time-step studies are used to assess the numerical accuracy of the methods. Nonsubiterative time-stepping schemes and schemes with physical time subiterations are subject to time-step limitations in practice that are removed by pseudo time sub-iterations. Computations for the circular-arc airfoil indicate that a one-equation turbulence model predicts the unsteady separated flow better than an algebraic turbulence model; also, the hysteresis with Mach number of the self-excited unsteadiness due to shock and boundary-layer separation is well predicted.

  9. Mechanisms of midsession reversal accuracy: Memory for preceding events and timing.

    PubMed

    Smith, Aaron P; Beckmann, Joshua S; Zentall, Thomas R

    2017-01-01

    The midsession reversal task involves a simultaneous discrimination between 2 stimuli (S1 and S2) in which, for the first half of each session, choice of S1 is reinforced and, for the last half, choice of S2 is reinforced. On this task, pigeons appear to time the occurrence of the reversal rather than using feedback from previous trials, resulting in increased numbers of errors. In the present experiments, we tested the hypothesis that pigeons make so many errors because they fail to remember the last response made and/or the consequence of making that response both of which are needed ideally as cues to respond on the next trial. To facilitate memory, during the 5-s intertrial interval, we differentially lit a houselight correlated with the prior response to S1 or S2 and maintained the hopper light when that response was correct. A control group received uncorrelated houselights and no maintained hopper light. To test for continued use of temporal information, both groups received probe sessions in which the intertrial interval was either halved or doubled. Providing relevant reminder cues of the stimulus chosen and its consequence resulted in improved reversal accuracy and reduced disruption from probe sessions compared with irrelevant cues. Nevertheless, despite the reminder cues, the pigeons in both groups appeared to continue to time the point in the session at which the reversal occurred. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  10. Improved Motor-Timing: Effects of Synchronized Metro-Nome Training on Golf Shot Accuracy

    PubMed Central

    Sommer, Marius; Rönnqvist, Louise

    2009-01-01

    This study investigates the effect of synchronized metronome training (SMT) on motor timing and how this training might affect golf shot accuracy. Twenty-six experienced male golfers participated (mean age 27 years; mean golf handicap 12.6) in this study. Pre- and post-test investigations of golf shots made by three different clubs were conducted by use of a golf simulator. The golfers were randomized into two groups: a SMT group and a Control group. After the pre-test, the golfers in the SMT group completed a 4-week SMT program designed to improve their motor timing, the golfers in the Control group were merely training their golf-swings during the same time period. No differences between the two groups were found from the pre-test outcomes, either for motor timing scores or for golf shot accuracy. However, the post-test results after the 4-weeks SMT showed evident motor timing improvements. Additionally, significant improvements for golf shot accuracy were found for the SMT group and with less variability in their performance. No such improvements were found for the golfers in the Control group. As with previous studies that used a SMT program, this study’s results provide further evidence that motor timing can be improved by SMT and that such timing improvement also improves golf accuracy. Key points This study investigates the effect of synchronized metronome training (SMT) on motor timing and how this training might affect golf shot accuracy. A randomized control group design was used. The 4 week SMT intervention showed significant improvements in motor timing, golf shot accuracy, and lead to less variability. We conclude that this study’s results provide further evidence that motor timing can be improved by SMT training and that such timing improvement also improves golf accuracy. PMID:24149608

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

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 28 Judicial Administration 1 2010-07-01 2010-07-01 false Responsibility for accuracy, completeness, currency, and integrity. 20.37 Section 20.37 Judicial Administration DEPARTMENT OF JUSTICE CRIMINAL JUSTICE INFORMATION SYSTEMS Federal Systems and Exchange of Criminal History Record Information § 20.37 Responsibility...

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

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 28 Judicial Administration 1 2013-07-01 2013-07-01 false Responsibility for accuracy, completeness, currency, and integrity. 20.37 Section 20.37 Judicial Administration DEPARTMENT OF JUSTICE CRIMINAL JUSTICE INFORMATION SYSTEMS Federal Systems and Exchange of Criminal History Record Information § 20.37 Responsibility...

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

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 28 Judicial Administration 1 2012-07-01 2012-07-01 false Responsibility for accuracy, completeness, currency, and integrity. 20.37 Section 20.37 Judicial Administration DEPARTMENT OF JUSTICE CRIMINAL JUSTICE INFORMATION SYSTEMS Federal Systems and Exchange of Criminal History Record Information § 20.37 Responsibility...

  14. 28 CFR 20.37 - Responsibility for accuracy, completeness, currency, and integrity.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 28 Judicial Administration 1 2014-07-01 2014-07-01 false Responsibility for accuracy, completeness, currency, and integrity. 20.37 Section 20.37 Judicial Administration DEPARTMENT OF JUSTICE CRIMINAL JUSTICE INFORMATION SYSTEMS Federal Systems and Exchange of Criminal History Record Information § 20.37 Responsibility...

  15. 28 CFR 20.37 - Responsibility for accuracy, completeness, currency, and integrity.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 28 Judicial Administration 1 2011-07-01 2011-07-01 false Responsibility for accuracy, completeness, currency, and integrity. 20.37 Section 20.37 Judicial Administration DEPARTMENT OF JUSTICE CRIMINAL JUSTICE INFORMATION SYSTEMS Federal Systems and Exchange of Criminal History Record Information § 20.37 Responsibility...

  16. On the Locus of Speed-Accuracy Trade-Off in Reaction Time: Inferences From the Lateralized Readiness Potential

    ERIC Educational Resources Information Center

    Rinkenauer, Gerhard; Osman, Allen; Ulrich, Rolf; Muller-Gethmann, Hiltraut; Mattes, Stefan

    2004-01-01

    Lateralized readiness potentials (LRPs) were used to determine the stage(s) of reaction time (RT) responsible for speed-accuracy trade-offs (SATs). Speeded decisions based on several types of information were examined in 3 experiments, involving, respectively, a line discrimination task, lexical decisions, and an Erikson flanker task. Three levels…

  17. 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…

  18. Response requirement and increases in accuracy produced by stimulant drugs in a 5-choice serial reaction-time task in rats.

    PubMed

    Koffarnus, Mikhail N; Katz, Jonathan L

    2011-02-01

    Increased signal-detection accuracy on the 5-choice serial reaction time (5-CSRT) task has been shown with drugs that are useful clinically in treating attention deficit hyperactivity disorder (ADHD), but these increases are often small and/or unreliable. By reducing the reinforcer frequency, it may be possible to increase the sensitivity of this task to pharmacologically induced improvements in accuracy. Rats were trained to respond on the 5-CSRT task on a fixed ratio (FR) 1, FR 3, or FR 10 schedule of reinforcement. Drugs that were and were not expected to enhance performance were then administered before experimental sessions. Significant increases in accuracy of signal detection were not typically obtained under the FR 1 schedule with any drug. However, d-amphetamine, methylphenidate, and nicotine typically increased accuracy under the FR 3 and FR 10 schedules. Increasing the FR requirement in the 5-CSRT task increases the likelihood of a positive result with clinically effective drugs, and may more closely resemble conditions in children with attention deficits.

  19. Estimation of accuracy of time synchronization obtained by means of clock transportation

    NASA Astrophysics Data System (ADS)

    Zhang, Yuzhen; Ma, Dekang; Jin, Wenjing; Zhao, Gang; Huang, Peicheng

    A portable clock experiment was carried out in October 1985 between Shanghai Observatory and Beijing Observatory using a small quartz clock made in Switzerland. The accuracy of time synchronization in 5 days is 70.18 microsec and the accuracy of determining the transmission time of short wave is satisfactory for reduction of the astronomical observations to the same master clock.

  20. 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.

  1. Computer simulation and discussion of high-accuracy laser direction finding in real time

    NASA Astrophysics Data System (ADS)

    Chen, Wenyi; Chen, Yongzhi

    1997-12-01

    On condition that CCD is used as the sensor, there are at least five methods that can be used to realize laser's direction finding with high accuracy. They are: image matching method, radiation center method, geometric center method, center of rectangle envelope method and center of maximum run length method. The first three can get the highest accuracy but working in real-time it is too complicated to realize and the cost is very expansive. The other two can also get high accuracy, and it is not difficult to realize working in real time. By using a single-chip microcomputer and an ordinary CCD camera a very simple system can get the position information of a laser beam. The data rate is 50 times per second.

  2. Classification Consistency and Accuracy for Complex Assessments Using Item Response Theory

    ERIC Educational Resources Information Center

    Lee, Won-Chan

    2010-01-01

    In this article, procedures are described for estimating single-administration classification consistency and accuracy indices for complex assessments using item response theory (IRT). This IRT approach was applied to real test data comprising dichotomous and polytomous items. Several different IRT model combinations were considered. Comparisons…

  3. 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. Copyright © 2015 Elsevier B.V. All rights reserved.

  4. An accuracy assessment of realtime GNSS time series toward semi- real time seafloor geodetic observation

    NASA Astrophysics Data System (ADS)

    Osada, Y.; Ohta, Y.; Demachi, T.; Kido, M.; Fujimoto, H.; Azuma, R.; Hino, R.

    2013-12-01

    Large interplate earthquake repeatedly occurred in Japan Trench. Recently, the detail crustal deformation revealed by the nation-wide inland GPS network called as GEONET by GSI. However, the maximum displacement region for interplate earthquake is mainly located offshore region. GPS/Acoustic seafloor geodetic observation (hereafter GPS/A) is quite important and useful for understanding of shallower part of the interplate coupling between subducting and overriding plates. We typically conduct GPS/A in specific ocean area based on repeated campaign style using research vessel or buoy. Therefore, we cannot monitor the temporal variation of seafloor crustal deformation in real time. The one of technical issue on real time observation is kinematic GPS analysis because kinematic GPS analysis based on reference and rover data. If the precise kinematic GPS analysis will be possible in the offshore region, it should be promising method for real time GPS/A with USV (Unmanned Surface Vehicle) and a moored buoy. We assessed stability, precision and accuracy of StarFireTM global satellites based augmentation system. We primarily tested for StarFire in the static condition. In order to assess coordinate precision and accuracy, we compared 1Hz StarFire time series and post-processed precise point positioning (PPP) 1Hz time series by GIPSY-OASIS II processing software Ver. 6.1.2 with three difference product types (ultra-rapid, rapid, and final orbits). We also used difference interval clock information (30 and 300 seconds) for the post-processed PPP processing. The standard deviation of real time StarFire time series is less than 30 mm (horizontal components) and 60 mm (vertical component) based on 1 month continuous processing. We also assessed noise spectrum of the estimated time series by StarFire and post-processed GIPSY PPP results. We found that the noise spectrum of StarFire time series is similar pattern with GIPSY-OASIS II processing result based on JPL rapid orbit

  5. Appetitive and aversive motivation in dysphoria: A time-domain and time-frequency study of response inhibition.

    PubMed

    Messerotti Benvenuti, Simone; Buodo, Giulia; Palomba, Daniela

    2017-04-01

    The study of emotional response inhibition could provide novel insight into dysphoria-related deficits in appetitive and aversive motivational systems. Therefore, dysphoric (N=21) and nondysphoric (N=21) participants completed an emotional Go/Nogo paradigm, including the presentation of pleasant, neutral and unpleasant pictures. Behavioral measures [reaction times (RTs), accuracy to Go and Nogo stimuli] and neural correlates (Go/Nogo-N2 and Go/Nogo-P3) of response inhibition were compared between the two groups. Time-frequency analysis was also used as a novel approach to disentangle the multiple processes underlying time-domain ERP data. A reduced Go/Nogo effect for P3 and oscillatory delta activity was found in response to pleasant and neutral, but not unpleasant, stimuli in dysphoric relative to nondysphoric individuals. These findings showed that dysphoric individuals need a reduced and/or less effortful response inhibition to pleasant stimuli, suggesting that dysphoria is characterized by under-engagement of appetitive rather than over-engagement of aversive motivational system. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Stability and accuracy of International Atomic Time TAI.

    NASA Astrophysics Data System (ADS)

    Thomas, C.

    Since the end of 1992, the quality of the timing data received at the BIPM has rapidly evolved dues to the extensive replacement of older designs of commercial Cs clocks. Consequently, the stability of the reference time scales has improved significantly. This was tested by running modified algorithms over the real clock data collected at the BIPM. Results of different studies are shown here; in particular the implementation of an upper relative contribution, chosen equal to 1.37% for any contributing clock, leads to σy(τ=40 d) = 1.8×10-15. The accuracy of TAI is estimated by the difference between the duration of the TAI scale interval and the SI second as produced on the rotating geoid by primary frequency standards. In this paper, TAI accuracy is evaluated from six primary frequency standards LPTF-FO1, PTB CS1, PTB CS2, PTB CS3, NIST-7 and SU MCsR 102 all corrected in a consistent manner for the gravitational shift and the black-body radiation shift. This led to a mean departure of the TAI scale interval of 1.8×10-14 s over 1995, known with a relative uncertainty of 0.5×10-14 (1σ).

  7. A real-time freehand ultrasound calibration system with automatic accuracy feedback and control.

    PubMed

    Chen, Thomas Kuiran; Thurston, Adrian D; Ellis, Randy E; Abolmaesumi, Purang

    2009-01-01

    This article describes a fully automatic, real-time, freehand ultrasound calibration system. The system was designed to be simple and sterilizable, intended for operating-room usage. The calibration system employed an automatic-error-retrieval and accuracy-control mechanism based on a set of ground-truth data. Extensive validations were conducted on a data set of 10,000 images in 50 independent calibration trials to thoroughly investigate the accuracy, robustness, and performance of the calibration system. On average, the calibration accuracy (measured in three-dimensional reconstruction error against a known ground truth) of all 50 trials was 0.66 mm. In addition, the calibration errors converged to submillimeter in 98% of all trials within 12.5 s on average. Overall, the calibration system was able to consistently, efficiently and robustly achieve high calibration accuracy with real-time performance.

  8. Biofeedback-based self-alert training reduces alpha activity and stabilizes accuracy in the Sustained Attention to Response Task.

    PubMed

    Braun, Niclas; Debener, Stefan; Sölle, Ariane; Kranczioch, Cornelia; Hildebrandt, Helmut

    2015-01-01

    Deficits in sustaining attention are common in various organic brain diseases. A recent study proposed self-alert training (SAT) as a technique to improve sustained attention. In the SAT, individuals learn to gain volitional control over their own state of arousal by means of electrodermal biofeedback. In this study, we investigated the behavioral, electrodermal, and electroencephalogram correlates of the SAT with a blinded, randomized, and active-controlled pre-post study design. Sustained attention capacity was assessed with the Sustained Attention to Response Task (SART). The SAT resulted in strong phasic increases in skin conductance response (SCR), but endogenous control of SCR without feedback was problematic. Electroencephalogram analysis revealed stronger alpha reduction during SART for the SAT than for the control group. Behaviorally, the SAT group performed more accurately and more slowly after intervention than the control group. The study provides further evidence that SAT helps to maintain SART accuracy over prolonged periods of time. Whether this accuracy is more related to sustained attention or response inhibition is discussed.

  9. 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.

  10. Accuracy of real time radiography burning rate measurement

    NASA Astrophysics Data System (ADS)

    Olaniyi, Bisola

    The design of a solid propellant rocket motor requires the determination of a propellant's burning-rate and its dependency upon environmental parameters. The requirement that the burning-rate be physically measured, establishes the need for methods and equipment to obtain such data. A literature review reveals that no measurement has provided the desired burning rate accuracy. In the current study, flash x-ray modeling and digitized film-density data were employed to predict motor-port area to length ratio. The pre-fired port-areas and base burning rate were within 2.5% and 1.2% of their known values, respectively. To verify the accuracy of the method, a continuous x-ray and a solid propellant rocket motor model (Plexiglas cylinder) were used. The solid propellant motor model was translated laterally through a real-time radiography system at different speeds simulating different burning rates. X-ray images were captured and the burning-rate was then determined. The measured burning rate was within 1.65% of the known values.

  11. Modeling aging effects on two-choice tasks: response signal and response time data.

    PubMed

    Ratcliff, Roger

    2008-12-01

    In the response signal paradigm, a test stimulus is presented, and then at one of a number of experimenter-determined times, a signal to respond is presented. Response signal, standard response time (RT), and accuracy data were collected from 19 college-age and 19 60- to 75-year-old participants in a numerosity discrimination task. The data were fit with 2 versions of the diffusion model. Response signal data were modeled by assuming a mixture of processes, those that have terminated before the signal and those that have not terminated; in the latter case, decisions are based on either partial information or guessing. The effects of aging on performance in the regular RT task were explained the same way in the models, with a 70- to 100-ms increase in the nondecision component of processing, more conservative decision criteria, and more variability across trials in drift and the nondecision component of processing, but little difference in drift rate (evidence). In the response signal task, the primary reason for a slower rise in the response signal functions for older participants was variability in the nondecision component of processing. Overall, the results were consistent with earlier fits of the diffusion model to the standard RT task for college-age participants and to the data from aging studies using this task in the standard RT procedure. Copyright (c) 2009 APA, all rights reserved.

  12. Modeling Aging Effects on Two-Choice Tasks: Response Signal and Response Time Data

    PubMed Central

    Ratcliff, Roger

    2009-01-01

    In the response signal paradigm, a test stimulus is presented, and then at one of a number of experimenter-determined times, a signal to respond is presented. Response signal, standard response time (RT), and accuracy data were collected from 19 college-age and 19 60- to 75-year-old participants in a numerosity discrimination task. The data were fit with 2 versions of the diffusion model. Response signal data were modeled by assuming a mixture of processes, those that have terminated before the signal and those that have not terminated; in the latter case, decisions are based on either partial information or guessing. The effects of aging on performance in the regular RT task were explained the same way in the models, with a 70- to 100-ms increase in the nondecision component of processing, more conservative decision criteria, and more variability across trials in drift and the nondecision component of processing, but little difference in drift rate (evidence). In the response signal task, the primary reason for a slower rise in the response signal functions for older participants was variability in the nondecision component of processing. Overall, the results were consistent with earlier fits of the diffusion model to the standard RT task for college-age participants and to the data from aging studies using this task in the standard RT procedure. PMID:19140659

  13. Cued Speech Transliteration: Effects of Speaking Rate and Lag Time on Production Accuracy

    PubMed Central

    Tessler, Morgan P.

    2016-01-01

    Many deaf and hard-of-hearing children rely on interpreters to access classroom communication. Although the exact level of access provided by interpreters in these settings is unknown, it is likely to depend heavily on interpreter accuracy (portion of message correctly produced by the interpreter) and the factors that govern interpreter accuracy. In this study, the accuracy of 12 Cued Speech (CS) transliterators with varying degrees of experience was examined at three different speaking rates (slow, normal, fast). Accuracy was measured with a high-resolution, objective metric in order to facilitate quantitative analyses of the effect of each factor on accuracy. Results showed that speaking rate had a large negative effect on accuracy, caused primarily by an increase in omitted cues, whereas the effect of lag time on accuracy, also negative, was quite small and explained just 3% of the variance. Increased experience level was generally associated with increased accuracy; however, high levels of experience did not guarantee high levels of accuracy. Finally, the overall accuracy of the 12 transliterators, 54% on average across all three factors, was low enough to raise serious concerns about the quality of CS transliteration services that (at least some) children receive in educational settings. PMID:27221370

  14. Deconvolution improves the accuracy and depth sensitivity of time-resolved measurements

    NASA Astrophysics Data System (ADS)

    Diop, Mamadou; St. Lawrence, Keith

    2013-03-01

    Time-resolved (TR) techniques have the potential to distinguish early- from late-arriving photons. Since light travelling through superficial tissue is detected earlier than photons that penetrate the deeper layers, time-windowing can in principle be used to improve the depth sensitivity of TR measurements. However, TR measurements also contain instrument contributions - referred to as the instrument-response-function (IRF) - which cause temporal broadening of the measured temporal-point-spread-function (TPSF). In this report, we investigate the influence of the IRF on pathlength-resolved absorption changes (Δμa) retrieved from TR measurements using the microscopic Beer-Lambert law (MBLL). TPSFs were acquired on homogeneous and two-layer tissue-mimicking phantoms with varying optical properties. The measured IRF and TPSFs were deconvolved to recover the distribution of time-of-flights (DTOFs) of the detected photons. The microscopic Beer-Lambert law was applied to early and late time-windows of the TPSFs and DTOFs to access the effects of the IRF on pathlength-resolved Δμa. The analysis showed that the late part of the TPSFs contains substantial contributions from early-arriving photons, due to the smearing effects of the IRF, which reduced its sensitivity to absorption changes occurring in deep layers. We also demonstrated that the effects of the IRF can be efficiently eliminated by applying a robust deconvolution technique, thereby improving the accuracy and sensitivity of TR measurements to deep-tissue absorption changes.

  15. Assessing cortical excitability in migraine: reliability of magnetic suppression of perceptual accuracy technique over time.

    PubMed

    Custers, Anouk; Mulleners, Wim M; Chronicle, Edward P

    2005-10-01

    To examine test-retest reliability of magnetic suppression of perceptual accuracy (MSPA) prior to its use as a marker of cortical excitability in a trial of migraine prophylactic agents. MSPA is a relatively novel avenue of research in headache, providing an opportunity to study cortical responsiveness objectively and noninvasively. However, little is known about the reliability of magnetic stimulation protocols such as MSPA in longitudinal research designs. We tested 10 healthy headache-free volunteers who had no family history of migraine. In 54 trials, they were briefly presented different three-letter combinations, flashed on a computer screen for 24 ms (target). After a brief interval, each target was followed by a single magnetic pulse through a 90-mm circular coil centered 7 cm above inion in the midline. The interval between target and magnetic pulse was systematically varied. Volunteers were requested to report as many letters as they had possibly identified. After 2 weeks, all volunteers were retested using identical methods. MSPA performance is expressed as a profile of response accuracy (ie, percentage of correctly identified letters) across target-pulse intervals. Profiles were characteristic of normal headache-free subjects at the first test. Analysis of variance revealed no significant difference in profiles between test and retest (F= 2.05; P= .136): the retest profiles are almost coincidental with the test profiles. MSPA is a safe and objective measure of cortical excitability, which is reliable over time. MSPA, therefore, shows excellent promise as a biological marker of cortical response in trials of migraine prophylactics.

  16. Meta-epidemiologic study showed frequent time trends in summary estimates from meta-analyses of diagnostic accuracy studies.

    PubMed

    Cohen, Jérémie F; Korevaar, Daniël A; Wang, Junfeng; Leeflang, Mariska M; Bossuyt, Patrick M

    2016-09-01

    To evaluate changes over time in summary estimates from meta-analyses of diagnostic accuracy studies. We included 48 meta-analyses from 35 MEDLINE-indexed systematic reviews published between September 2011 and January 2012 (743 diagnostic accuracy studies; 344,015 participants). Within each meta-analysis, we ranked studies by publication date. We applied random-effects cumulative meta-analysis to follow how summary estimates of sensitivity and specificity evolved over time. Time trends were assessed by fitting a weighted linear regression model of the summary accuracy estimate against rank of publication. The median of the 48 slopes was -0.02 (-0.08 to 0.03) for sensitivity and -0.01 (-0.03 to 0.03) for specificity. Twelve of 96 (12.5%) time trends in sensitivity or specificity were statistically significant. We found a significant time trend in at least one accuracy measure for 11 of the 48 (23%) meta-analyses. Time trends in summary estimates are relatively frequent in meta-analyses of diagnostic accuracy studies. Results from early meta-analyses of diagnostic accuracy studies should be considered with caution. Copyright © 2016 Elsevier Inc. All rights reserved.

  17. 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.

  18. Cued Speech Transliteration: Effects of Speaking Rate and Lag Time on Production Accuracy.

    PubMed

    Krause, Jean C; Tessler, Morgan P

    2016-10-01

    Many deaf and hard-of-hearing children rely on interpreters to access classroom communication. Although the exact level of access provided by interpreters in these settings is unknown, it is likely to depend heavily on interpreter accuracy (portion of message correctly produced by the interpreter) and the factors that govern interpreter accuracy. In this study, the accuracy of 12 Cued Speech (CS) transliterators with varying degrees of experience was examined at three different speaking rates (slow, normal, fast). Accuracy was measured with a high-resolution, objective metric in order to facilitate quantitative analyses of the effect of each factor on accuracy. Results showed that speaking rate had a large negative effect on accuracy, caused primarily by an increase in omitted cues, whereas the effect of lag time on accuracy, also negative, was quite small and explained just 3% of the variance. Increased experience level was generally associated with increased accuracy; however, high levels of experience did not guarantee high levels of accuracy. Finally, the overall accuracy of the 12 transliterators, 54% on average across all three factors, was low enough to raise serious concerns about the quality of CS transliteration services that (at least some) children receive in educational settings. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  19. The power of timing: Adding a time-to-completion cutoff to the Word Choice Test and Recognition Memory Test improves classification accuracy.

    PubMed

    Erdodi, Laszlo A; Tyson, Bradley T; Shahein, Ayman G; Lichtenstein, Jonathan D; Abeare, Christopher A; Pelletier, Chantalle L; Zuccato, Brandon G; Kucharski, Brittany; Roth, Robert M

    2017-05-01

    The Recognition Memory Test (RMT) and Word Choice Test (WCT) are structurally similar, but psychometrically different. Previous research demonstrated that adding a time-to-completion cutoff improved the classification accuracy of the RMT. However, the contribution of WCT time-cutoffs to improve the detection of invalid responding has not been investigated. The present study was designed to evaluate the classification accuracy of time-to-completion on the WCT compared to the accuracy score and the RMT. Both tests were administered to 202 adults (M age  = 45.3 years, SD = 16.8; 54.5% female) clinically referred for neuropsychological assessment in counterbalanced order as part of a larger battery of cognitive tests. Participants obtained lower and more variable scores on the RMT (M = 44.1, SD = 7.6) than on the WCT (M = 46.9, SD = 5.7). Similarly, they took longer to complete the recognition trial on the RMT (M = 157.2 s,SD = 71.8) than the WCT (M = 137.2 s, SD = 75.7). The optimal cutoff on the RMT (≤43) produced .60 sensitivity at .87 specificity. The optimal cutoff on the WCT (≤47) produced .57 sensitivity at .87 specificity. Time-cutoffs produced comparable classification accuracies for both RMT (≥192 s; .48 sensitivity at .88 specificity) and WCT (≥171 s; .49 sensitivity at .91 specificity). They also identified an additional 6-10% of the invalid profiles missed by accuracy score cutoffs, while maintaining good specificity (.93-.95). Functional equivalence was reached at accuracy scores ≤43 (RMT) and ≤47 (WCT) or time-to-completion ≥192 s (RMT) and ≥171 s (WCT). Time-to-completion cutoffs are valuable additions to both tests. They can function as independent validity indicators or enhance the sensitivity of accuracy scores without requiring additional measures or extending standard administration time.

  20. Accurate and efficient calculation of response times for groundwater flow

    NASA Astrophysics Data System (ADS)

    Carr, Elliot J.; Simpson, Matthew J.

    2018-03-01

    We study measures of the amount of time required for transient flow in heterogeneous porous media to effectively reach steady state, also known as the response time. Here, we develop a new approach that extends the concept of mean action time. Previous applications of the theory of mean action time to estimate the response time use the first two central moments of the probability density function associated with the transition from the initial condition, at t = 0, to the steady state condition that arises in the long time limit, as t → ∞ . This previous approach leads to a computationally convenient estimation of the response time, but the accuracy can be poor. Here, we outline a powerful extension using the first k raw moments, showing how to produce an extremely accurate estimate by making use of asymptotic properties of the cumulative distribution function. Results are validated using an existing laboratory-scale data set describing flow in a homogeneous porous medium. In addition, we demonstrate how the results also apply to flow in heterogeneous porous media. Overall, the new method is: (i) extremely accurate; and (ii) computationally inexpensive. In fact, the computational cost of the new method is orders of magnitude less than the computational effort required to study the response time by solving the transient flow equation. Furthermore, the approach provides a rigorous mathematical connection with the heuristic argument that the response time for flow in a homogeneous porous medium is proportional to L2 / D , where L is a relevant length scale, and D is the aquifer diffusivity. Here, we extend such heuristic arguments by providing a clear mathematical definition of the proportionality constant.

  1. A space system for high-accuracy global time and frequency comparison of clocks

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

    A Space Shuttle experiment in which a hydrogen maser clock on board the Space Shuttle will be compared with clocks on the ground using two-way microwave and short pulse laser signals is described. The accuracy goal for the experiment is 1 nsec or better for the time transfer and 10 to the minus 14th power for the frequency comparison. A direct frequency comparison of primary standards at the 10 to the minus 14th power accuracy level is a unique feature of the proposed system. Both time and frequency transfer will be accomplished by microwave transmission, while the laser signals provide calibration of the system as well as subnanosecond time transfer.

  2. Accounting for speed-accuracy tradeoff in perceptual learning

    PubMed Central

    Liu, Charles C.; Watanabe, Takeo

    2011-01-01

    In the perceptual learning (PL) literature, researchers typically focus on improvements in accuracy, such as d’. In contrast, researchers who investigate the practice of cognitive skills focus on improvements in response times (RT). Here, we argue for the importance of accounting for both accuracy and RT in PL experiments, due to the phenomenon of speed-accuracy tradeoff (SAT): at a given level of discriminability, faster responses tend to produce more errors. A formal model of the decision process, such as the diffusion model, can explain the SAT. In this model, a parameter known as the drift rate represents the perceptual strength of the stimulus, where higher drift rates lead to more accurate and faster responses. We applied the diffusion model to analyze responses from a yes-no coherent motion detection task. The results indicate that observers do not use a fixed threshold for evidence accumulation, so changes in the observed accuracy may not provide the most appropriate estimate of learning. Instead, our results suggest that SAT can be accounted for by a modeling approach, and that drift rates offer a promising index of PL. PMID:21958757

  3. Accounting for speed-accuracy tradeoff in perceptual learning.

    PubMed

    Liu, Charles C; Watanabe, Takeo

    2012-05-15

    In the perceptual learning (PL) literature, researchers typically focus on improvements in accuracy, such as d'. In contrast, researchers who investigate the practice of cognitive skills focus on improvements in response times (RT). Here, we argue for the importance of accounting for both accuracy and RT in PL experiments, due to the phenomenon of speed-accuracy tradeoff (SAT): at a given level of discriminability, faster responses tend to produce more errors. A formal model of the decision process, such as the diffusion model, can explain the SAT. In this model, a parameter known as the drift rate represents the perceptual strength of the stimulus, where higher drift rates lead to more accurate and faster responses. We applied the diffusion model to analyze responses from a yes-no coherent motion detection task. The results indicate that observers do not use a fixed threshold for evidence accumulation, so changes in the observed accuracy may not provide the most appropriate estimate of learning. Instead, our results suggest that SAT can be accounted for by a modeling approach, and that drift rates offer a promising index of PL. Copyright © 2011 Elsevier Ltd. All rights reserved.

  4. Accuracy analysis for triangulation and tracking based on time-multiplexed structured light.

    PubMed

    Wagner, Benjamin; Stüber, Patrick; Wissel, Tobias; Bruder, Ralf; Schweikard, Achim; Ernst, Floris

    2014-08-01

    The authors' research group is currently developing a new optical head tracking system for intracranial radiosurgery. This tracking system utilizes infrared laser light to measure features of the soft tissue on the patient's forehead. These features are intended to offer highly accurate registration with respect to the rigid skull structure by means of compensating for the soft tissue. In this context, the system also has to be able to quickly generate accurate reconstructions of the skin surface. For this purpose, the authors have developed a laser scanning device which uses time-multiplexed structured light to triangulate surface points. The accuracy of the authors' laser scanning device is analyzed and compared for different triangulation methods. These methods are given by the Linear-Eigen method and a nonlinear least squares method. Since Microsoft's Kinect camera represents an alternative for fast surface reconstruction, the authors' results are also compared to the triangulation accuracy of the Kinect device. Moreover, the authors' laser scanning device was used for tracking of a rigid object to determine how this process is influenced by the remaining triangulation errors. For this experiment, the scanning device was mounted to the end-effector of a robot to be able to calculate a ground truth for the tracking. The analysis of the triangulation accuracy of the authors' laser scanning device revealed a root mean square (RMS) error of 0.16 mm. In comparison, the analysis of the triangulation accuracy of the Kinect device revealed a RMS error of 0.89 mm. It turned out that the remaining triangulation errors only cause small inaccuracies for the tracking of a rigid object. Here, the tracking accuracy was given by a RMS translational error of 0.33 mm and a RMS rotational error of 0.12°. This paper shows that time-multiplexed structured light can be used to generate highly accurate reconstructions of surfaces. Furthermore, the reconstructed point sets can be

  5. Two Approaches to Estimation of Classification Accuracy Rate under Item Response Theory

    ERIC Educational Resources Information Center

    Lathrop, Quinn N.; Cheng, Ying

    2013-01-01

    Within the framework of item response theory (IRT), there are two recent lines of work on the estimation of classification accuracy (CA) rate. One approach estimates CA when decisions are made based on total sum scores, the other based on latent trait estimates. The former is referred to as the Lee approach, and the latter, the Rudner approach,…

  6. Working times of elastomeric impression materials determined by dimensional accuracy.

    PubMed

    Tan, E; Chai, J; Wozniak, W T

    1996-01-01

    The working times of five poly(vinyl siloxane) impression materials were estimated by evaluating the dimensional accuracy of stone dies of impressions of a standard model made at successive time intervals. The stainless steel standard model was represented by two abutments having known distances between landmarks in three dimensions. Three dimensions in the x-, y-, and z-axes of the stone dies were measured with a traveling microscope. A time interval was rejected as being within the working time if the percentage change of the resultant dies, in any dimension, was statistically different from those measured from stone dies from previous time intervals. The absolute dimensions of those dies from the rejected time interval also must have exceeded all those from previous time intervals. Results showed that the working times estimated with this method generally were about 30 seconds longer than those recommended by the manufacturers.

  7. Acute, intermediate intensity exercise, and speed and accuracy in working memory tasks: a meta-analytical comparison of effects.

    PubMed

    McMorris, Terry; Sproule, John; Turner, Anthony; Hale, Beverley J

    2011-03-01

    The purpose of this study was to compare, using meta-analytic techniques, the effect of acute, intermediate intensity exercise on the speed and accuracy of performance of working memory tasks. It was hypothesized that acute, intermediate intensity exercise would have a significant beneficial effect on response time and that effect sizes for response time and accuracy data would differ significantly. Random-effects meta-analysis showed a significant, beneficial effect size for response time, g=-1.41 (p<0.001) but a significant detrimental effect size, g=0.40 (p<0.01), for accuracy. There was a significant difference between effect sizes (Z(diff)=3.85, p<0.001). It was concluded that acute, intermediate intensity exercise has a strong beneficial effect on speed of response in working memory tasks but a low to moderate, detrimental one on accuracy. There was no support for a speed-accuracy trade-off. It was argued that exercise-induced increases in brain concentrations of catecholamines result in faster processing but increases in neural noise may negatively affect accuracy. 2010 Elsevier Inc. All rights reserved.

  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. The effect of orientation difference in fused deposition modeling of ABS polymer on the processing time, dimension accuracy, and strength

    NASA Astrophysics Data System (ADS)

    Tanoto, Yopi Y.; Anggono, Juliana; Siahaan, Ian H.; Budiman, Wesley

    2017-01-01

    There are several parameters that must be set before manufacturing a product using 3D printing. These parameters include the orientation deposition of that product, type of material, form fill, fill density, and other parameters. The finished product of 3D printing has some responses that can be observed, measured, and tested. Some of those responses are the processing time, the dimensions of the end product, its surface roughness and the mechanical properties, i.e. its yield strength, ultimate tensile strength, and impact resistance. This research was conducted to study the relationship between process parameters of 3D printing machine using a technology of fused deposition modeling (FDM) and the generated responses. The material used was ABS plastic that was commonly used in the industry. Understanding the relationship between the parameters and the responses thus the resulting product can be manufactured to meet the user needs. Three different orientations in depositing the ABS polymer named XY(first orientation), YX (second orientation), and ZX (third orientation) were studied. Processing time, dimensional accuracy, and the product strength were the responses that were measured and tested. The study reports that the printing process with third orientation was the fastest printing process with the processing time 2432 seconds followed by orientation 1 and 2 with a processing time of 2688 and 2780 seconds respectively. Dimension accuracy was also measured from the width and the length of gauge area of tensile test specimens printed in comparison with the dimensions required by ASTM 638-02. It was found that the smallest difference was in thickness dimension, i.e. 0.1 mm thicker in printed sample using second orientation than as required by the standard. The smallest thickness deviation from the standard was measured in width dimension of a sample printed using first orientation (0.13 mm). As with the length dimension, the closest dimension to the standard was

  10. Travel time data collection for measurement of advanced traveler information systems accuracy

    DOT National Transportation Integrated Search

    2003-06-01

    The objective of this white paper is to recommend an approach to measuring ATIS travel time accuracy so that ITS planners might have the data they need to make cost effective decisions regarding deployment of surveillance technologies to support ATIS...

  11. 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.

  12. Does Physical Loading Affect The Speed and Accuracy of Tactical Decision-Making in Elite Junior Soccer Players?

    PubMed Central

    Frýbort, Pavel; Kokštejn, Jakub; Musálek, Martin; Süss, Vladimír

    2016-01-01

    A soccer player’s capability to control and manage his behaviour in a game situation is a prerequisite, reflecting not only swift and accurate tactical decision-making, but also prompt implementation of a motor task during intermittent exercise conditions. The purpose of this study was to analyse the relationship between varying exercise intensity and the visual-motor response time and the accuracy of motor response in an offensive game situation in soccer. The participants (n = 42) were male, semi-professional, soccer players (M age 18.0 ± 0.9 years) and trained five times a week. Each player performed four different modes of exercise intensity on the treadmill (motor inactivity, aerobic, intermittent and anaerobic activity). After the end of each exercise, visual-motor response time and accuracy of motor response were assessed. Players’ motion was captured by digital video camera. ANOVA indicated no significant difference (p = 0.090) in the accuracy of motor response between the four exercise intensity modes. Practical significance (Z-test = 0.31) was found in visual-motor response time between exercise with dominant involvement of aerobic metabolism, and intense intermittent exercise. A medium size effect (Z-test = 0.34) was also found in visual-motor response time between exercise with dominant involvement of aerobic metabolism and exercise with dominant involvement of anaerobic metabolism, which was confirmed by ANOVA (897.02 ± 57.46 vs. 940.95 ± 71.14; p = 0.002). The results showed that different modes of exercise intensity do not adversely affect the accuracy of motor responses; however, high-intensity exercise has a negative effect on visual-motor response time in comparison to moderate intensity exercise. Key points Different exercise intensity modes did not affect the accuracy of motor response. Anaerobic, highly intensive short-term exercise significantly decreased the visual-motor response time in comparison with aerobic exercise. Further

  13. Does Physical Loading Affect The Speed and Accuracy of Tactical Decision-Making in Elite Junior Soccer Players?

    PubMed

    Frýbort, Pavel; Kokštejn, Jakub; Musálek, Martin; Süss, Vladimír

    2016-06-01

    A soccer player's capability to control and manage his behaviour in a game situation is a prerequisite, reflecting not only swift and accurate tactical decision-making, but also prompt implementation of a motor task during intermittent exercise conditions. The purpose of this study was to analyse the relationship between varying exercise intensity and the visual-motor response time and the accuracy of motor response in an offensive game situation in soccer. The participants (n = 42) were male, semi-professional, soccer players (M age 18.0 ± 0.9 years) and trained five times a week. Each player performed four different modes of exercise intensity on the treadmill (motor inactivity, aerobic, intermittent and anaerobic activity). After the end of each exercise, visual-motor response time and accuracy of motor response were assessed. Players' motion was captured by digital video camera. ANOVA indicated no significant difference (p = 0.090) in the accuracy of motor response between the four exercise intensity modes. Practical significance (Z-test = 0.31) was found in visual-motor response time between exercise with dominant involvement of aerobic metabolism, and intense intermittent exercise. A medium size effect (Z-test = 0.34) was also found in visual-motor response time between exercise with dominant involvement of aerobic metabolism and exercise with dominant involvement of anaerobic metabolism, which was confirmed by ANOVA (897.02 ± 57.46 vs. 940.95 ± 71.14; p = 0.002). The results showed that different modes of exercise intensity do not adversely affect the accuracy of motor responses; however, high-intensity exercise has a negative effect on visual-motor response time in comparison to moderate intensity exercise. Key pointsDifferent exercise intensity modes did not affect the accuracy of motor response.Anaerobic, highly intensive short-term exercise significantly decreased the visual-motor response time in comparison with aerobic exercise.Further research

  14. Comparison of vacuum rise time, vacuum limit accuracy, and occlusion break surge of 3 new phacoemulsification systems.

    PubMed

    Han, Young Keun; Miller, Kevin M

    2009-08-01

    To compare vacuum rise time, vacuum limit accuracy, and occlusion break surge of 3 new phacoemulsification machines. Jules Stein Eye Institute and Department of Ophthalmology, David Geffen School of Medicine at UCLA, Los Angeles, California, USA. The vacuum rise time under normal and enhanced aspiration modes, vacuum limit accuracy, and occlusion break surge of the Infiniti Vision System, Stellaris Vision Enhancement System, and WhiteStar Signature Phacoemulsification System were tested. Vacuum rise time and limit accuracy were measured at limit settings of 400 mm Hg and 600 mm Hg. Surge area was recorded at vacuum limit settings of 200 mm Hg, 300 mm Hg, 400 mm Hg, and 500 mm Hg. The Infiniti had the fastest vacuum rise times under normal and enhanced aspiration modes. At 4 seconds, the vacuum limit accuracy was greatest with the Infiniti at the 400 mm Hg limit and the Signature at the 600 mm Hg limit. The Stellaris did not reach either vacuum target. The Infiniti performed better than the other 2 machines during testing of occlusion break surge at all vacuum limit settings above 200 mm Hg. Under controlled laboratory test conditions, the Infiniti had the fastest vacuum rise time, greatest vacuum limit accuracy at 400 mm Hg, and least occlusion break surge. These results can be explained by the lower compliance of the Infiniti system.

  15. Quantifying and estimating the predictive accuracy for censored time-to-event data with competing risks.

    PubMed

    Wu, Cai; Li, Liang

    2018-05-15

    This paper focuses on quantifying and estimating the predictive accuracy of prognostic models for time-to-event outcomes with competing events. We consider the time-dependent discrimination and calibration metrics, including the receiver operating characteristics curve and the Brier score, in the context of competing risks. To address censoring, we propose a unified nonparametric estimation framework for both discrimination and calibration measures, by weighting the censored subjects with the conditional probability of the event of interest given the observed data. The proposed method can be extended to time-dependent predictive accuracy metrics constructed from a general class of loss functions. We apply the methodology to a data set from the African American Study of Kidney Disease and Hypertension to evaluate the predictive accuracy of a prognostic risk score in predicting end-stage renal disease, accounting for the competing risk of pre-end-stage renal disease death, and evaluate its numerical performance in extensive simulation studies. Copyright © 2018 John Wiley & Sons, Ltd.

  16. Workload Capacity: A Response Time-Based Measure of Automation Dependence.

    PubMed

    Yamani, Yusuke; McCarley, Jason S

    2016-05-01

    An experiment used the workload capacity measure C(t) to quantify the processing efficiency of human-automation teams and identify operators' automation usage strategies in a speeded decision task. Although response accuracy rates and related measures are often used to measure the influence of an automated decision aid on human performance, aids can also influence response speed. Mean response times (RTs), however, conflate the influence of the human operator and the automated aid on team performance and may mask changes in the operator's performance strategy under aided conditions. The present study used a measure of parallel processing efficiency, or workload capacity, derived from empirical RT distributions as a novel gauge of human-automation performance and automation dependence in a speeded task. Participants performed a speeded probabilistic decision task with and without the assistance of an automated aid. RT distributions were used to calculate two variants of a workload capacity measure, COR(t) and CAND(t). Capacity measures gave evidence that a diagnosis from the automated aid speeded human participants' responses, and that participants did not moderate their own decision times in anticipation of diagnoses from the aid. Workload capacity provides a sensitive and informative measure of human-automation performance and operators' automation dependence in speeded tasks. © 2016, Human Factors and Ergonomics Society.

  17. Fourth-grade children's dietary recall accuracy is influenced by retention interval (target period and interview time).

    PubMed

    Baxter, Suzanne Domel; Hardin, James W; Guinn, Caroline H; Royer, Julie A; Mackelprang, Alyssa J; Smith, Albert F

    2009-05-01

    For a 24-hour dietary recall, two possible target periods are the prior 24 hours (24 hours immediately preceding the interview time) and previous day (midnight to midnight of the day before the interview), and three possible interview times are morning, afternoon, and evening. Target period and interview time determine the retention interval (elapsed time between to-be-reported meals and the interview), which, along with intervening meals, can influence reporting accuracy. The effects of target period and interview time on children's accuracy for reporting school meals during 24-hour dietary recalls were investigated. DESIGN AND SUBJECTS/SETTING: During the 2004-2005, 2005-2006, and 2006-2007 school years in Columbia, SC, each of 374 randomly selected fourth-grade children (96% African American) was observed eating two consecutive school meals (breakfast and lunch) and interviewed to obtain a 24-hour dietary recall using one of six conditions defined by crossing two target periods with three interview times. Each condition had 62 or 64 children (half boys). Accuracy for reporting school meals was quantified by calculating rates for omissions (food items observed eaten but unreported) and intrusions (food items reported eaten but unobserved); a measure of total inaccuracy combined errors for reporting food items and amounts. For each accuracy measure, analysis of variance was conducted with target period, interview time, their interaction, sex, interviewer, and school year in the model. There was a target-period effect and a target-period by interview-time interaction on omission rates, intrusion rates, and total inaccuracy (six P values <0.004). For prior-24-hour recalls compared to previous-day recalls, and for prior-24-hour recalls in the afternoon and evening compared to previous-day recalls in the afternoon and evening, omission rates were better by one third, intrusion rates were better by one half, and total inaccuracy was better by one third. To enhance

  18. Relationships among the cervical mucus urea and acetone, accuracy of insemination timing, and sperm survival in Holstein cows.

    PubMed

    Beran, J; Stádník, L; Ducháček, J; Okrouhlá, M; Doležalová, M; Kadlecová, V; Ptáček, M

    2013-11-01

    The objectives of this study were to evaluate the relationships among urea and acetone content in cows' cervical mucus (CM), its crystallization type (CT) and sperm survival (SS) after timed AI. Samples of CM were collected from 192 Holstein cows treated by Ovsynch(®) protocol. Analysis of the urea and acetone content for identification of the metabolic status, the arborization test for evaluation of insemination timing and the short-term heat test of SS for assessment of its suitability as a biological matrix were performed. The data set was analyzed by the GLM procedure using SAS(®). The results documented the existence of substantial differences in individual response to the Ovsynch(®) protocol causing insemination of 55.2% cows at an inappropriate time. The urea content was found as a possible indicator of a cow's metabolism and/or of insemination timing, concentrations of less than 500 mg/L corresponded (P<0.05-0.01) to the cows' expected response to timed AI. The greater the urea content, the greater the proportion of cows inseminated at an inappropriate time. Effects (P<0.05-0.01) of CT, urea and acetone content on SS were determined. The greatest values of SS were detected in cows with an expected response to precisely timed oestrus documented by the corresponding CT. Greater values of urea (>260 mg/L) and acetone (>5mg/L) negatively affected SS as well (P<0.05-0.01). The results confirmed that the accuracy of insemination timing can be affected by the metabolism intensity, just as CM quality directly influences sperm survival. Copyright © 2013 Elsevier B.V. All rights reserved.

  19. Examination of standardized patient performance: accuracy and consistency of six standardized patients over time.

    PubMed

    Erby, Lori A H; Roter, Debra L; Biesecker, Barbara B

    2011-11-01

    To explore the accuracy and consistency of standardized patient (SP) performance in the context of routine genetic counseling, focusing on elements beyond scripted case items including general communication style and affective demeanor. One hundred seventy-seven genetic counselors were randomly assigned to counsel one of six SPs. Videotapes and transcripts of the sessions were analyzed to assess consistency of performance across four dimensions. Accuracy of script item presentation was high; 91% and 89% in the prenatal and cancer cases. However, there were statistically significant differences among SPs in the accuracy of presentation, general communication style, and some aspects of affective presentation. All SPs were rated as presenting with similarly high levels of realism. SP performance over time was generally consistent, with some small but statistically significant differences. These findings demonstrate that well-trained SPs can not only perform the factual elements of a case with high degrees of accuracy and realism; but they can also maintain sufficient levels of uniformity in general communication style and affective demeanor over time to support their use in even the demanding context of genetic counseling. Results indicate a need for an additional focus in training on consistency between different SPs. Copyright © 2010. Published by Elsevier Ireland Ltd.

  20. Network Dynamics Underlying Speed-Accuracy Trade-Offs in Response to Errors

    PubMed Central

    Agam, Yigal; Carey, Caitlin; Barton, Jason J. S.; Dyckman, Kara A.; Lee, Adrian K. C.; Vangel, Mark; Manoach, Dara S.

    2013-01-01

    The ability to dynamically and rapidly adjust task performance based on its outcome is fundamental to adaptive, flexible behavior. Over trials of a task, responses speed up until an error is committed and after the error responses slow down. These dynamic adjustments serve to optimize performance and are well-described by the speed-accuracy trade-off (SATO) function. We hypothesized that SATOs based on outcomes reflect reciprocal changes in the allocation of attention between the internal milieu and the task-at-hand, as indexed by reciprocal changes in activity between the default and dorsal attention brain networks. We tested this hypothesis using functional MRI to examine the pattern of network activation over a series of trials surrounding and including an error. We further hypothesized that these reciprocal changes in network activity are coordinated by the posterior cingulate cortex (PCC) and would rely on the structural integrity of its white matter connections. Using diffusion tensor imaging, we examined whether fractional anisotropy of the posterior cingulum bundle correlated with the magnitude of reciprocal changes in network activation around errors. As expected, reaction time (RT) in trials surrounding errors was consistent with predictions from the SATO function. Activation in the default network was: (i) inversely correlated with RT, (ii) greater on trials before than after an error and (iii) maximal at the error. In contrast, activation in the right intraparietal sulcus of the dorsal attention network was (i) positively correlated with RT and showed the opposite pattern: (ii) less activation before than after an error and (iii) the least activation on the error. Greater integrity of the posterior cingulum bundle was associated with greater reciprocity in network activation around errors. These findings suggest that dynamic changes in attention to the internal versus external milieu in response to errors underlie SATOs in RT and are mediated by the PCC

  1. 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

  2. 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.

  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. 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

    2017-06-01

    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.

  5. One process is not enough! A speed-accuracy tradeoff study of recognition memory.

    PubMed

    Boldini, Angela; Russo, Riccardo; Avons, S E

    2004-04-01

    Speed-accuracy tradeoff (SAT) methods have been used to contrast single- and dual-process accounts of recognition memory. In these procedures, subjects are presented with individual test items and are required to make recognition decisions under various time constraints. In this experiment, we presented word lists under incidental learning conditions, varying the modality of presentation and level of processing. At test, we manipulated the interval between each visually presented test item and a response signal, thus controlling the amount of time available to retrieve target information. Study-test modality match had a beneficial effect on recognition accuracy at short response-signal delays (< or =300 msec). Conversely, recognition accuracy benefited more from deep than from shallow processing at study only at relatively long response-signal delays (> or =300 msec). The results are congruent with views suggesting that both fast familiarity and slower recollection processes contribute to recognition memory.

  6. 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

  7. Trading Speed and Accuracy by Coding Time: A Coupled-circuit Cortical Model

    PubMed Central

    Standage, Dominic; You, Hongzhi; Wang, Da-Hui; Dorris, Michael C.

    2013-01-01

    Our actions take place in space and time, but despite the role of time in decision theory and the growing acknowledgement that the encoding of time is crucial to behaviour, few studies have considered the interactions between neural codes for objects in space and for elapsed time during perceptual decisions. The speed-accuracy trade-off (SAT) provides a window into spatiotemporal interactions. Our hypothesis is that temporal coding determines the rate at which spatial evidence is integrated, controlling the SAT by gain modulation. Here, we propose that local cortical circuits are inherently suited to the relevant spatial and temporal coding. In simulations of an interval estimation task, we use a generic local-circuit model to encode time by ‘climbing’ activity, seen in cortex during tasks with a timing requirement. The model is a network of simulated pyramidal cells and inhibitory interneurons, connected by conductance synapses. A simple learning rule enables the network to quickly produce new interval estimates, which show signature characteristics of estimates by experimental subjects. Analysis of network dynamics formally characterizes this generic, local-circuit timing mechanism. In simulations of a perceptual decision task, we couple two such networks. Network function is determined only by spatial selectivity and NMDA receptor conductance strength; all other parameters are identical. To trade speed and accuracy, the timing network simply learns longer or shorter intervals, driving the rate of downstream decision processing by spatially non-selective input, an established form of gain modulation. Like the timing network's interval estimates, decision times show signature characteristics of those by experimental subjects. Overall, we propose, demonstrate and analyse a generic mechanism for timing, a generic mechanism for modulation of decision processing by temporal codes, and we make predictions for experimental verification. PMID:23592967

  8. 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

  9. 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.

  10. 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…

  11. Implementation of High Time Delay Accuracy of Ultrasonic Phased Array Based on Interpolation CIC Filter

    PubMed Central

    Liu, Peilu; Li, Xinghua; Li, Haopeng; Su, Zhikun; Zhang, Hongxu

    2017-01-01

    In order to improve the accuracy of ultrasonic phased array focusing time delay, analyzing the original interpolation Cascade-Integrator-Comb (CIC) filter, an 8× interpolation CIC filter parallel algorithm was proposed, so that interpolation and multichannel decomposition can simultaneously process. Moreover, we summarized the general formula of arbitrary multiple interpolation CIC filter parallel algorithm and established an ultrasonic phased array focusing time delay system based on 8× interpolation CIC filter parallel algorithm. Improving the algorithmic structure, 12.5% of addition and 29.2% of multiplication was reduced, meanwhile the speed of computation is still very fast. Considering the existing problems of the CIC filter, we compensated the CIC filter; the compensated CIC filter’s pass band is flatter, the transition band becomes steep, and the stop band attenuation increases. Finally, we verified the feasibility of this algorithm on Field Programming Gate Array (FPGA). In the case of system clock is 125 MHz, after 8× interpolation filtering and decomposition, time delay accuracy of the defect echo becomes 1 ns. Simulation and experimental results both show that the algorithm we proposed has strong feasibility. Because of the fast calculation, small computational amount and high resolution, this algorithm is especially suitable for applications with high time delay accuracy and fast detection. PMID:29023385

  12. Implementation of High Time Delay Accuracy of Ultrasonic Phased Array Based on Interpolation CIC Filter.

    PubMed

    Liu, Peilu; Li, Xinghua; Li, Haopeng; Su, Zhikun; Zhang, Hongxu

    2017-10-12

    In order to improve the accuracy of ultrasonic phased array focusing time delay, analyzing the original interpolation Cascade-Integrator-Comb (CIC) filter, an 8× interpolation CIC filter parallel algorithm was proposed, so that interpolation and multichannel decomposition can simultaneously process. Moreover, we summarized the general formula of arbitrary multiple interpolation CIC filter parallel algorithm and established an ultrasonic phased array focusing time delay system based on 8× interpolation CIC filter parallel algorithm. Improving the algorithmic structure, 12.5% of addition and 29.2% of multiplication was reduced, meanwhile the speed of computation is still very fast. Considering the existing problems of the CIC filter, we compensated the CIC filter; the compensated CIC filter's pass band is flatter, the transition band becomes steep, and the stop band attenuation increases. Finally, we verified the feasibility of this algorithm on Field Programming Gate Array (FPGA). In the case of system clock is 125 MHz, after 8× interpolation filtering and decomposition, time delay accuracy of the defect echo becomes 1 ns. Simulation and experimental results both show that the algorithm we proposed has strong feasibility. Because of the fast calculation, small computational amount and high resolution, this algorithm is especially suitable for applications with high time delay accuracy and fast detection.

  13. Evaluation of the Horizontal and Vertical Accuracy of GNSS Survey Observations from a Real-Time Network

    NASA Astrophysics Data System (ADS)

    Allahyari, M.; Olsen, M. J.; Gillins, D. T.; Dennis, M. L.

    2016-12-01

    Many current surveying standards in the United States require several long-duration, static Global Navigation Satellite System (GNSS) observations to derive high-accuracy geodetic coordinates. However, over the past decade, many entities have established real-time GNSS networks (RTNs), which could reduce the field time for establishing geodetic control from hours to minutes. To evaluate the accuracy of RTN GNSS observations, data collected from two National Geodetic Survey (NGS) surveys in South Carolina and Oregon were studied. The objectives were to: 1) determine the accuracy of a real-time observation as a function of duration; 2) examine the influence of including GLONASS (Russia's version of GPS); 3) compare results using a single base to the full RTN network solution; and 4) assess the effect of baseline length on accuracy. In South Carolina, 360 observations ranging from 5 to 600 seconds were collected on 20 passive marks using RTN and single-base solutions, both with GPS+GLONASS and GPS-only. In Oregon, 18 passive marks were observed from 5 to 900 seconds using GPS-only with the RTN, and with GPS+GLONASS and GPS-only from a single-base. To develop "truth" coordinates, at least 30 hours of static GPS data were also collected on all marks. Each static survey session was post-processed in OPUS-Projects, and the resulting vectors were used to build survey networks that were least-squares adjusted using the NGS software ADJUST. The resulting coordinates provided the basis for evaluating the accuracy of the real-time observations. Results from this study indicate great potential in the use of RTNs for accurate derivation of geodetic coordinates. Both case studies showed an optimal observation duration of 180 seconds. RTN data tended to be more accurate and consistent than single-base data, and GLONASS slightly improved accuracy. A key benefit of GLONASS was the ability to obtain more fixed solutions at longer baseline lengths than single-base solutions.

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kadir, A. B. A.; Priharti, W.; Samat, S. B.

    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.

  15. Acquisition of decision making criteria: reward rate ultimately beats accuracy.

    PubMed

    Balci, Fuat; Simen, Patrick; Niyogi, Ritwik; Saxe, Andrew; Hughes, Jessica A; Holmes, Philip; Cohen, Jonathan D

    2011-02-01

    Speed-accuracy trade-offs 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 trade-offs in single session, two-alternative forced-choice tasks. We investigated whether humans acquired optimal speed-accuracy trade-offs 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: (1) favoring accuracy over reward rate and (2) 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.

  16. 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.

  17. Time-dependent classification accuracy curve under marker-dependent sampling.

    PubMed

    Zhu, Zhaoyin; Wang, Xiaofei; Saha-Chaudhuri, Paramita; Kosinski, Andrzej S; George, Stephen L

    2016-07-01

    Evaluating the classification accuracy of a candidate biomarker signaling the onset of disease or disease status is essential for medical decision making. A good biomarker would accurately identify the patients who are likely to progress or die at a particular time in the future or who are in urgent need for active treatments. To assess the performance of a candidate biomarker, the receiver operating characteristic (ROC) curve and the area under the ROC curve (AUC) are commonly used. In many cases, the standard simple random sampling (SRS) design used for biomarker validation studies is costly and inefficient. In order to improve the efficiency and reduce the cost of biomarker validation, marker-dependent sampling (MDS) may be used. In a MDS design, the selection of patients to assess true survival time is dependent on the result of a biomarker assay. In this article, we introduce a nonparametric estimator for time-dependent AUC under a MDS design. The consistency and the asymptotic normality of the proposed estimator is established. Simulation shows the unbiasedness of the proposed estimator and a significant efficiency gain of the MDS design over the SRS design. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

    PubMed

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

    2015-05-01

    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. 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. 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). The Timed Up and Go test was shown to be a predictor of sarcopenia in elderly hospitalized patients.

  19. Rigorous accuracy assessment for 3D reconstruction using time-series Dual Fluoroscopy (DF) image pairs

    NASA Astrophysics Data System (ADS)

    Al-Durgham, Kaleel; Lichti, Derek D.; Kuntze, Gregor; Ronsky, Janet

    2017-06-01

    High-speed biplanar videoradiography, or clinically referred to as dual fluoroscopy (DF), imaging systems are being used increasingly for skeletal kinematics analysis. Typically, a DF system comprises two X-ray sources, two image intensifiers and two high-speed video cameras. The combination of these elements provides time-series image pairs of articulating bones of a joint, which permits the measurement of bony rotation and translation in 3D at high temporal resolution (e.g., 120-250 Hz). Assessment of the accuracy of 3D measurements derived from DF imaging has been the subject of recent research efforts by several groups, however with methodological limitations. This paper presents a novel and simple accuracy assessment procedure based on using precise photogrammetric tools. We address the fundamental photogrammetry principles for the accuracy evaluation of an imaging system. Bundle adjustment with selfcalibration is used for the estimation of the system parameters. The bundle adjustment calibration uses an appropriate sensor model and applies free-network constraints and relative orientation stability constraints for a precise estimation of the system parameters. A photogrammetric intersection of time-series image pairs is used for the 3D reconstruction of a rotating planar object. A point-based registration method is used to combine the 3D coordinates from the intersection and independently surveyed coordinates. The final DF accuracy measure is reported as the distance between 3D coordinates from image intersection and the independently surveyed coordinates. The accuracy assessment procedure is designed to evaluate the accuracy over the full DF image format and a wide range of object rotation. Experiment of reconstruction of a rotating planar object reported an average positional error of 0.44 +/- 0.2 mm in the derived 3D coordinates (minimum 0.05 and maximum 1.2 mm).

  20. Predictive display design for the vehicles with time delay in dynamic response

    NASA Astrophysics Data System (ADS)

    Efremov, A. V.; Tiaglik, M. S.; Irgaleev, I. H.; Efremov, E. V.

    2018-02-01

    The two ways for the improvement of flying qualities are considered: the predictive display (PD) and the predictive display integrated with the flight control system (FCS). The both ways allow to transforming the controlled element dynamics in the crossover frequency range, to improve the accuracy of tracking and to suppress the effect of time delay in the vehicle response too. The technique for optimization of the predictive law is applied to the landing task. The results of the mathematical modeling and experimental investigations carried out for this task are considered in the paper.

  1. Linear response approach to active Brownian particles in time-varying activity fields

    NASA Astrophysics Data System (ADS)

    Merlitz, Holger; Vuijk, Hidde D.; Brader, Joseph; Sharma, Abhinav; Sommer, Jens-Uwe

    2018-05-01

    In a theoretical and simulation study, active Brownian particles (ABPs) in three-dimensional bulk systems are exposed to time-varying sinusoidal activity waves that are running through the system. A linear response (Green-Kubo) formalism is applied to derive fully analytical expressions for the torque-free polarization profiles of non-interacting particles. The activity waves induce fluxes that strongly depend on the particle size and may be employed to de-mix mixtures of ABPs or to drive the particles into selected areas of the system. Three-dimensional Langevin dynamics simulations are carried out to verify the accuracy of the linear response formalism, which is shown to work best when the particles are small (i.e., highly Brownian) or operating at low activity levels.

  2. Accuracy and Precision of Visual Stimulus Timing in PsychoPy: No Timing Errors in Standard Usage

    PubMed Central

    Garaizar, Pablo; Vadillo, Miguel A.

    2014-01-01

    In a recent report published in PLoS ONE, we found that the performance of PsychoPy degraded with very short timing intervals, suggesting that it might not be perfectly suitable for experiments requiring the presentation of very brief stimuli. The present study aims to provide an updated performance assessment for the most recent version of PsychoPy (v1.80) under different hardware/software conditions. Overall, the results show that PsychoPy can achieve high levels of precision and accuracy in the presentation of brief visual stimuli. Although occasional timing errors were found in very demanding benchmarking tests, there is no reason to think that they can pose any problem for standard experiments developed by researchers. PMID:25365382

  3. Hidden Markov Item Response Theory Models for Responses and Response Times.

    PubMed

    Molenaar, Dylan; Oberski, Daniel; Vermunt, Jeroen; De Boeck, Paul

    2016-01-01

    Current approaches to model responses and response times to psychometric tests solely focus on between-subject differences in speed and ability. Within subjects, speed and ability are assumed to be constants. Violations of this assumption are generally absorbed in the residual of the model. As a result, within-subject departures from the between-subject speed and ability level remain undetected. These departures may be of interest to the researcher as they reflect differences in the response processes adopted on the items of a test. In this article, we propose a dynamic approach for responses and response times based on hidden Markov modeling to account for within-subject differences in responses and response times. A simulation study is conducted to demonstrate acceptable parameter recovery and acceptable performance of various fit indices in distinguishing between different models. In addition, both a confirmatory and an exploratory application are presented to demonstrate the practical value of the modeling approach.

  4. Prefrontal consolidation supports the attainment of fear memory accuracy

    PubMed Central

    Vieira, Philip A.; Lovelace, Jonathan W.; Corches, Alex; Rashid, Asim J.; Josselyn, Sheena A.

    2014-01-01

    The neural mechanisms underlying the attainment of fear memory accuracy for appropriate discriminative responses to aversive and nonaversive stimuli are unclear. Considerable evidence indicates that coactivator of transcription and histone acetyltransferase cAMP response element binding protein (CREB) binding protein (CBP) is critically required for normal neural function. CBP hypofunction leads to severe psychopathological symptoms in human and cognitive abnormalities in genetic mutant mice with severity dependent on the neural locus and developmental time of the gene inactivation. Here, we showed that an acute hypofunction of CBP in the medial prefrontal cortex (mPFC) results in a disruption of fear memory accuracy in mice. In addition, interruption of CREB function in the mPFC also leads to a deficit in auditory discrimination of fearful stimuli. While mice with deficient CBP/CREB signaling in the mPFC maintain normal responses to aversive stimuli, they exhibit abnormal responses to similar but nonrelevant stimuli when compared to control animals. These data indicate that improvement of fear memory accuracy involves mPFC-dependent suppression of fear responses to nonrelevant stimuli. Evidence from a context discriminatory task and a newly developed task that depends on the ability to distinguish discrete auditory cues indicated that CBP-dependent neural signaling within the mPFC circuitry is an important component of the mechanism for disambiguating the meaning of fear signals with two opposing values: aversive and nonaversive. PMID:25031365

  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. Color, dispersion, and exposure time in performance on rotated figure recognition.

    PubMed

    Huang, Kuo-Chen; Lee, Shin-Tsann; Chang, Chun-Chieh

    2008-10-01

    This study investigated the effects of dispersion, color, and rotation of figures on recognition under varied exposure times. A total of 30 women and 15 men, Taiwanese college students ages 18 to 20 years (M = 19.1, SD = 1.2), participated. Subjects were to recognize a target figure and respond with its location in each stimulus by pressing a mouse button. Analysis showed that the effect of rotation on accuracy was significant. Accuracy for the rotation of 180 degrees was greater than those for 60 degrees and 300 degrees. Exposure time also significantly influenced accuracy. The accuracy was greater for 2 and 3 sec. than for 1 sec. No significant effects on accuracy were associated with dispersion and color, and neither had any interactive effect on accuracy. Dispersion significantly affected the response time as response time for dispersion under 0.4 and 0.5 conditions were shorter than those under 0.2 and 0.3 conditions. Significantly less response time was needed for rotation of 180 degrees than for 60 degrees and 300 degrees conditions. Response time was longer for red figures than for blue, green, and yellow figures. No significant effect on response time was associated with duration of exposure. Two interactive two-way effects were found: dispersion x color of figure and dispersion x rotation. Implications for figure or icon design are discussed.

  7. [Study on high accuracy detection of multi-component gas in oil-immerse power transformer].

    PubMed

    Fan, Jie; Chen, Xiao; Huang, Qi-Feng; Zhou, Yu; Chen, Gang

    2013-12-01

    In order to solve the problem of low accuracy and mutual interference in multi-component gas detection, a kind of multi-component gas detection network with high accuracy was designed. A semiconductor laser with narrow bandwidth was utilized as light source and a novel long-path gas cell was also used in this system. By taking the single sine signal to modulate the spectrum of laser and using space division multiplexing (SDM) and time division multiplexing (TDM) technique, the detection of multi-component gas was achieved. The experiments indicate that the linearity relevance coefficient is 0. 99 and the measurement relative error is less than 4%. The system dynamic response time is less than 15 s, by filling a volume of multi-component gas into the gas cell gradually. The system has advantages of high accuracy and quick response, which can be used in the fault gas on-line monitoring for power transformers in real time.

  8. 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…

  9. Diagnostic accuracy of magnetic resonance imaging techniques for treatment response evaluation in patients with high-grade glioma, a systematic review and meta-analysis.

    PubMed

    van Dijken, Bart R J; van Laar, Peter Jan; Holtman, Gea A; van der Hoorn, Anouk

    2017-10-01

    Treatment response assessment in high-grade gliomas uses contrast enhanced T1-weighted MRI, but is unreliable. Novel advanced MRI techniques have been studied, but the accuracy is not well known. Therefore, we performed a systematic meta-analysis to assess the diagnostic accuracy of anatomical and advanced MRI for treatment response in high-grade gliomas. Databases were searched systematically. Study selection and data extraction were done by two authors independently. Meta-analysis was performed using a bivariate random effects model when ≥5 studies were included. Anatomical MRI (five studies, 166 patients) showed a pooled sensitivity and specificity of 68% (95%CI 51-81) and 77% (45-93), respectively. Pooled apparent diffusion coefficients (seven studies, 204 patients) demonstrated a sensitivity of 71% (60-80) and specificity of 87% (77-93). DSC-perfusion (18 studies, 708 patients) sensitivity was 87% (82-91) with a specificity of 86% (77-91). DCE-perfusion (five studies, 207 patients) sensitivity was 92% (73-98) and specificity was 85% (76-92). The sensitivity of spectroscopy (nine studies, 203 patients) was 91% (79-97) and specificity was 95% (65-99). Advanced techniques showed higher diagnostic accuracy than anatomical MRI, the highest for spectroscopy, supporting the use in treatment response assessment in high-grade gliomas. • Treatment response assessment in high-grade gliomas with anatomical MRI is unreliable • Novel advanced MRI techniques have been studied, but diagnostic accuracy is unknown • Meta-analysis demonstrates that advanced MRI showed higher diagnostic accuracy than anatomical MRI • Highest diagnostic accuracy for spectroscopy and perfusion MRI • Supports the incorporation of advanced MRI in high-grade glioma treatment response assessment.

  10. Human Subcutaneous Tissue Response to Glucose Sensors: Macrophages Accumulation Impact on Sensor Accuracy.

    PubMed

    Rigla, Mercedes; Pons, Belén; Rebasa, Pere; Luna, Alexis; Pozo, Francisco Javier; Caixàs, Assumpta; Villaplana, Maria; Subías, David; Bella, Maria Rosa; Combalia, Neus

    2018-04-01

    Subcutaneous (s.c.) glucose sensors have become a key component in type 1 diabetes management. However, their usability is limited by the impact of foreign body response (FBR) on their duration, reliability, and accuracy. Our study gives the first description of human acute and subacute s.c. response to glucose sensors, showing the changes observed in the sensor surface, the inflammatory cells involved in the FBR and their relationship with sensor performance. Twelve obese patients (seven type 2 diabetes) underwent two abdominal biopsies comprising the surrounding area where they had worn two glucose sensors: the first one inserted 7 days before and the second one 24 h before biopsy procedure. Samples were processed and studied to describe tissue changes by two independent pathologists (blind regarding sensor duration). Macrophages quantification was studied by immunohistochemistry methods in the area surrounding the sensor (CD68, CD163). Sensor surface changes were studied by scanning electron microscopy. Seven-day continuous glucose monitoring records were considered inaccurate when mean absolute relative difference was higher than 10%. Pathologists were able to correctly classify all the biopsies regarding sensor duration. Acute response (24 h) was characterized by the presence of neutrophils while macrophages were the main cell involved in subacute inflammation. The number of macrophages around the insertion hole was higher for less accurate sensors compared with those performing more accurately (32.6 ± 14 vs. 10.6 ± 1 cells/0.01 mm 2 ; P < 0.05). The accumulation of macrophages at the sensor-tissue interface is related with decrease in accuracy of the glucose measure.

  11. The effect of cerebral palsy on arithmetic accuracy is mediated by working memory, intelligence, early numeracy, and instruction time.

    PubMed

    Jenks, Kathleen M; de Moor, Jan; van Lieshout, Ernest C D M; Maathuis, Karel G B; Keus, Inge; Gorter, Jan Willem

    2007-01-01

    The development of addition and subtraction accuracy was assessed in first graders with cerebral palsy (CP) in both mainstream (16) and special education (41) and a control group of first graders in mainstream education (16). The control group out-performed the CP groups in addition and subtraction accuracy and this difference could not be fully explained by differences in intelligence. Both CP groups showed evidence of working memory deficits. The three groups exhibited different developmental patterns in the area of early numeracy skills. Children with CP in special education were found to receive less arithmetic instruction and instruction time was positively related to arithmetic accuracy. Structural equation modeling revealed that the effect of CP on arithmetic accuracy is mediated by intelligence, working memory, early numeracy, and instruction time.

  12. Impact of new clock technologies on the stability and accuracy of the International Atomic Time TAI.

    NASA Astrophysics Data System (ADS)

    Thomas, C.

    1997-05-01

    The BIPM Time Section is in charge of the generation of the reference time scales TAI and UTC. Both time scales are obtained in deferred-time by combining the data front a number of atomic clocks spread worldwide. The accuracy of TAI is estimated by the departure between the duration of the TAI scale interval and the SI second as produced on the rotating geoid by primary frequency standards. It is now possible to estimate TAI accuracy through the combination of results obtained from six different primary standards: LPTF-FO1, PTB CS1, PTB CS2, PTB CS3, NIST-7, and SU MCsR 102, all corrected for the black-body radiation shift. This led to a mean departure of the TAI scale interval of +2.0×10-14s over 1995, known with a relative uncertainty of 0.5×10-14(1σ).

  13. Impact of time-resolved MRA on diagnostic accuracy in patients with symptomatic peripheral artery disease of the calf station.

    PubMed

    Hansmann, Jan; Michaely, Henrik J; Morelli, John N; Diehl, Steffen J; Meyer, Mathias; Schoenberg, Stefan O; Attenberger, Ulrike I

    2013-12-01

    The purpose of this article is to evaluate the added diagnostic accuracy of time-resolved MR angiography (MRA) of the calves compared with continuous-table-movement MRA in patients with symptomatic lower extremity peripheral artery disease (PAD) using digital subtraction angiography (DSA) correlation. Eighty-four consecutive patients with symptomatic PAD underwent a low-dose 3-T MRA protocol, consisting of continuous-table-movement MRA, acquired from the diaphragm to the calves, and an additional time-resolved MRA of the calves; 0.1 mmol/kg body weight (bw) of contrast material was used (0.07 mmol/kg bw for continuous-table-movement MRA and 0.03 mmol/kg bw for time-resolved MRA). Two radiologists rated image quality on a 4-point scale and stenosis degree on a 3-point scale. An additional assessment determined the degree of venous contamination and whether time-resolved MRA improved diagnostic confidence. The accuracy of stenosis gradation with continuous-table-movement and time-resolved MRA was compared with that of DSA as a correlation. Overall diagnostic accuracy was calculated for continuous-table-movement and time-resolved MRA. Median image quality was rated as good for 578 vessel segments with continuous-table-movement MRA and as excellent for 565 vessel segments with time-resolved MRA. Interreader agreement was excellent (κ = 0.80-0.84). Venous contamination interfered with diagnosis in more than 60% of continuous-table-movement MRA examinations. The degree of stenosis was assessed for 340 vessel segments. The diagnostic accuracies (continuous-table-movement MRA/time-resolved MRA) combined for the readers were obtained for the tibioperoneal trunk (84%/93%), anterior tibial (69%/87%), posterior tibial (85%/91%), and peroneal (67%/81%) arteries. The addition of time-resolved MRA improved diagnostic confidence in 69% of examinations. The addition of time-resolved MRA at the calf station improves diagnostic accuracy over continuous-table-movement MRA alone in

  14. The accuracy of real-time procedure coding by theatre nurses: a comparison with the central national system.

    PubMed

    Maclean, Donald; Younes, Hakim Ben; Forrest, Margaret; Towers, Hazel K

    2012-03-01

    Accurate and timely clinical data are required for clinical and organisational purposes and is especially important for patient management, audit of surgical performance and the electronic health record. The recent introduction of computerised theatre management systems has enabled real-time (point-of-care) operative procedure coding by clinical staff. However the accuracy of these data is unknown. The aim of this Scottish study was to compare the accuracy of theatre nurses' real-time coding on the local theatre management system with the central Scottish Morbidity Record (SMR01). Paired procedural codes were recorded, qualitatively graded for precision and compared (n = 1038). In this study, real-time, point-of-care coding by theatre nurses resulted in significant coding errors compared with the central SMR01 database. Improved collaboration between full-time coders and clinical staff using computerised decision support systems is suggested.

  15. Factors Affecting Accuracy and Time Requirements of a Glucose Oxidase-Peroxidase Assay for Determination of Glucose

    USDA-ARS?s Scientific Manuscript database

    Accurate and rapid assays for glucose are desirable for analysis of glucose and starch in food and feedstuffs. An established colorimetric glucose oxidase-peroxidase method for glucose was modified to reduce analysis time, and evaluated for factors that affected accuracy. Time required to perform t...

  16. Prefrontal consolidation supports the attainment of fear memory accuracy.

    PubMed

    Vieira, Philip A; Lovelace, Jonathan W; Corches, Alex; Rashid, Asim J; Josselyn, Sheena A; Korzus, Edward

    2014-08-01

    The neural mechanisms underlying the attainment of fear memory accuracy for appropriate discriminative responses to aversive and nonaversive stimuli are unclear. Considerable evidence indicates that coactivator of transcription and histone acetyltransferase cAMP response element binding protein (CREB) binding protein (CBP) is critically required for normal neural function. CBP hypofunction leads to severe psychopathological symptoms in human and cognitive abnormalities in genetic mutant mice with severity dependent on the neural locus and developmental time of the gene inactivation. Here, we showed that an acute hypofunction of CBP in the medial prefrontal cortex (mPFC) results in a disruption of fear memory accuracy in mice. In addition, interruption of CREB function in the mPFC also leads to a deficit in auditory discrimination of fearful stimuli. While mice with deficient CBP/CREB signaling in the mPFC maintain normal responses to aversive stimuli, they exhibit abnormal responses to similar but nonrelevant stimuli when compared to control animals. These data indicate that improvement of fear memory accuracy involves mPFC-dependent suppression of fear responses to nonrelevant stimuli. Evidence from a context discriminatory task and a newly developed task that depends on the ability to distinguish discrete auditory cues indicated that CBP-dependent neural signaling within the mPFC circuitry is an important component of the mechanism for disambiguating the meaning of fear signals with two opposing values: aversive and nonaversive. © 2014 Vieira et al.; Published by Cold Spring Harbor Laboratory Press.

  17. 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 Appeal...

  18. 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 Appeal...

  19. 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 Appeal...

  20. 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 Appeal...

  1. Low clinical diagnostic accuracy of early vs advanced Parkinson disease: clinicopathologic study.

    PubMed

    Adler, Charles H; Beach, Thomas G; Hentz, Joseph G; Shill, Holly A; Caviness, John N; Driver-Dunckley, Erika; Sabbagh, Marwan N; Sue, Lucia I; Jacobson, Sandra A; Belden, Christine M; Dugger, Brittany N

    2014-07-29

    Determine diagnostic accuracy of a clinical diagnosis of Parkinson disease (PD) using neuropathologic diagnosis as the gold standard. Data from the Arizona Study of Aging and Neurodegenerative Disorders were used to determine the predictive value of a clinical PD diagnosis, using 2 clinical diagnostic confidence levels, PossPD (never treated or not clearly responsive) and ProbPD (responsive to medications). Neuropathologic diagnosis was the gold standard. Based on first visit, 9 of 34 (26%) PossPD cases had neuropathologically confirmed PD while 80 of 97 (82%) ProbPD cases had confirmed PD. PD was confirmed in 8 of 15 (53%) ProbPD cases with <5 years of disease duration and 72 of 82 (88%) with ≥5 years of disease duration. Using final diagnosis at time of death, 91 of 107 (85%) ProbPD cases had confirmed PD. Clinical variables that improved diagnostic accuracy were medication response, motor fluctuations, dyskinesias, and hyposmia. Using neuropathologic findings of PD as the gold standard, this study establishes the novel findings of only 26% accuracy for a clinical diagnosis of PD in untreated or not clearly responsive subjects, 53% accuracy in early PD responsive to medication (<5 years' duration), and >85% diagnostic accuracy of longer duration, medication-responsive PD. Caution is needed when interpreting clinical studies of PD, especially studies of early disease that do not have autopsy confirmation. The need for a tissue or other diagnostic biomarker is reinforced. This study provides Class II evidence that a clinical diagnosis of PD identifies patients who will have pathologically confirmed PD with a sensitivity of 88% and specificity of 68%. © 2014 American Academy of Neurology.

  2. Time-Accuracy Functions for Determining Process and Person Differences: An Application to Cognitive Aging.

    ERIC Educational Resources Information Center

    Kliegl, Reinhold; And Others

    1994-01-01

    Tests with 2 pairs of tasks differing in cognitive complexity performed by 20 young and 20 old adults support a model for the determination of time-accuracy functions (TAFs) for individual participants. Findings replicate the established interactions between age and task complexity in the context of TAFs. (SLD)

  3. The influences of task repetition, napping, time of day, and instruction on the Sustained Attention to Response Task.

    PubMed

    van Schie, Mojca K M; Alblas, Eva E; Thijs, Roland D; Fronczek, Rolf; Lammers, Gert Jan; van Dijk, J Gert

    2014-01-01

    The Sustained Attention to Response Task (SART) helps to quantify vigilance impairments.Previous studies, in which five SART sessions on one day were administered, demonstrated worse performance during the first session than during the others. The present study comprises two experiments to identify a cause of this phenomenon. Experiment 1, counting eighty healthy participants, assessed effects of repetition,napping, and time of day on SART performance through a between-groups design. The SART was performed twice in the morning or twice in the afternoon; half of the participants took a 20-minute nap before the second SART. A strong correlation between error count and reaction time (RT) suggested effects of test instruction. Participants gave equal weight to speed and accuracy in Experiment 1; therefore, results of 20 participants were compared to those of 20 additional participants who were told to prefer accuracy (Experiment 2). The average SART error count in Experiment 1 was 10.1; the median RT was 280 ms. Neither repetition nor napping influenced error count or RT. Time of day did not influence error count, but RT was significantly longer for morning than for afternoon SARTs. The additional participants in Experiment 2 had a 49% lower error count and a 14% higher RT than the participants in Experiment 1. Error counts reduced by 50% from the first to the second session of Experiment 2, irrespective of napping or time of day. Preferring accuracy over speed was associated with a significantly lower error count. The data suggest that a worse performance in the first SART session only occurs when instructing participants to prefer accuracy, which is caused by repetition, not by napping or time of day. We advise that participants are instructed to prefer accuracy over speed when performing the SART and that a full practice session is included.

  4. 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.

  5. Impact of heart disease and calibration interval on accuracy of pulse transit time-based blood pressure estimation.

    PubMed

    Ding, Xiaorong; Zhang, Yuanting; Tsang, Hon Ki

    2016-02-01

    Continuous blood pressure (BP) measurement without a cuff is advantageous for the early detection and prevention of hypertension. The pulse transit time (PTT) method has proven to be promising for continuous cuffless BP measurement. However, the problem of accuracy is one of the most challenging aspects before the large-scale clinical application of this method. Since PTT-based BP estimation relies primarily on the relationship between PTT and BP under certain assumptions, estimation accuracy will be affected by cardiovascular disorders that impair this relationship and by the calibration frequency, which may violate these assumptions. This study sought to examine the impact of heart disease and the calibration interval on the accuracy of PTT-based BP estimation. The accuracy of a PTT-BP algorithm was investigated in 37 healthy subjects and 48 patients with heart disease at different calibration intervals, namely 15 min, 2 weeks, and 1 month after initial calibration. The results showed that the overall accuracy of systolic BP estimation was significantly lower in subjects with heart disease than in healthy subjects, but diastolic BP estimation was more accurate in patients than in healthy subjects. The accuracy of systolic and diastolic BP estimation becomes less reliable with longer calibration intervals. These findings demonstrate that both heart disease and the calibration interval can influence the accuracy of PTT-based BP estimation and should be taken into consideration to improve estimation accuracy.

  6. 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…

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Shchory, Tal; Schifter, Dan; Lichtman, Rinat

    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 trackingmore » 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.« less

  8. Tracking accuracy of a real-time fiducial tracking system for patient positioning and monitoring in radiation therapy.

    PubMed

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

    2010-11-15

    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. 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. 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. This novel radioactive tracking technology has the potential to be useful in accurate target localization and real-time monitoring for radiation therapy. Copyright © 2010 Elsevier Inc. All rights reserved.

  9. 7 CFR 27.97 - Ascertaining the accuracy of price quotations.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... cotton in each spot market shall be responsible for providing accurate and timely price, quality, and... ascertaining the accuracy of the price quotations in each designated spot market. The Cotton Division will... will collect and analyze pertinent information on the prices and values of spot cotton from each spot...

  10. Early Response to treatment in Eating Disorders: A Systematic Review and a Diagnostic Test Accuracy Meta-Analysis.

    PubMed

    Nazar, Bruno Palazzo; Gregor, Louise Kathrine; Albano, Gaia; Marchica, Angelo; Coco, Gianluca Lo; Cardi, Valentina; Treasure, Janet

    2017-03-01

    Early response to eating disorders treatment is thought to predict a later favourable outcome. A systematic review of the literature and meta-analyses examined the robustness of this concept. The criteria used across studies to define early response were summarised following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Diagnostic Test Accuracy methodology was used to estimate the size of the effect. Findings from 24 studies were synthesized and data from 14 studies were included in the meta-analysis. In Anorexia Nervosa, the odds ratio of early response predicting remission was 4.85(95%CI: 2.94-8.01) and the summary Area Under the Curve (AUC) = .77. In Bulimia Nervosa, the odds ratio was 2.75(95%CI:1.24-6.09) and AUC = .67. For Binge Eating Disorder, the odds ratio was 5.01(95%CI: 3.38-7.42) and AUC = .71. Early behaviour change accurately predicts later symptom remission for Anorexia Nervosa and Binge Eating Disorder but there is less predictive accuracy for Bulimia Nervosa. Copyright © 2016 John Wiley & Sons, Ltd and Eating Disorders Association. Copyright © 2016 John Wiley & Sons, Ltd and Eating Disorders Association.

  11. 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.

  12. Gated audiovisual speech identification in silence vs. noise: effects on time and accuracy

    PubMed Central

    Moradi, Shahram; Lidestam, Björn; Rönnberg, Jerker

    2013-01-01

    This study investigated the degree to which audiovisual presentation (compared to auditory-only presentation) affected isolation point (IPs, the amount of time required for the correct identification of speech stimuli using a gating paradigm) in silence and noise conditions. The study expanded on the findings of Moradi et al. (under revision), using the same stimuli, but presented in an audiovisual instead of an auditory-only manner. The results showed that noise impeded the identification of consonants and words (i.e., delayed IPs and lowered accuracy), but not the identification of final words in sentences. In comparison with the previous study by Moradi et al., it can be concluded that the provision of visual cues expedited IPs and increased the accuracy of speech stimuli identification in both silence and noise. The implication of the results is discussed in terms of models for speech understanding. PMID:23801980

  13. Response Mixture Modeling: Accounting for Heterogeneity in Item Characteristics across Response Times.

    PubMed

    Molenaar, Dylan; de Boeck, Paul

    2018-06-01

    In item response theory modeling of responses and response times, it is commonly assumed that the item responses have the same characteristics across the response times. However, heterogeneity might arise in the data if subjects resort to different response processes when solving the test items. These differences may be within-subject effects, that is, a subject might use a certain process on some of the items and a different process with different item characteristics on the other items. If the probability of using one process over the other process depends on the subject's response time, within-subject heterogeneity of the item characteristics across the response times arises. In this paper, the method of response mixture modeling is presented to account for such heterogeneity. Contrary to traditional mixture modeling where the full response vectors are classified, response mixture modeling involves classification of the individual elements in the response vector. In a simulation study, the response mixture model is shown to be viable in terms of parameter recovery. In addition, the response mixture model is applied to a real dataset to illustrate its use in investigating within-subject heterogeneity in the item characteristics across response times.

  14. Accuracy and reading time for six strategies using digital breast tomosynthesis in women with mammographically negative dense breasts.

    PubMed

    Tagliafico, Alberto Stefano; Calabrese, Massimo; Bignotti, Bianca; Signori, Alessio; Fisci, Erica; Rossi, Federica; Valdora, Francesca; Houssami, Nehmat

    2017-12-01

    To compare six strategies using digital breast tomosynthesis in women with mammographically negative dense breasts. This is a substudy of the 'ASTOUND' trial. 163 women who underwent tomosynthesis with synthetically reconstructed projection images (S-2D) inclusive of 13 (7.9%) cases diagnosed with breast cancer at histopathology after surgery were evaluated. Accuracy measures and screen-reading time of six reading strategies were assessed: (A) Single reading of S-2D alone, (B) single reading of tomosynthesis alone, (C) single reading of joint interpretation of tomosynthesis + S-2D, (D) double-reading of S-2D alone, (E) double reading of tomosynthesis alone, (F) double reading of joint interpretation of tomosynthesis + S-2D. The median age of the patients was 53 years (range, 36-88 years). The highest global accuracy was obtained with double reading of tomosynthesis + S2D (F) with an AUC of 0.979 (p<0.001) and a mean reading time of 154 s versus 34 s for the fastest strategy (single reading of S-2D alone). The AUCs for the other five strategies did not differ from each other. Double reading of tomosynthesis+ S2D had the best accuracy of six screen-reading strategies although it had the longest reading time. • Tomosynthesis acquisitions are progressively implemented with reconstructed synthesized 2D images • Double reading using S-2D plus tomosynthesis had the highest global accuracy (p<0.001). • Double reading of S-2D plus tomosynthesis increased reading time.

  15. A study on low-cost, high-accuracy, and real-time stereo vision algorithms for UAV power line inspection

    NASA Astrophysics Data System (ADS)

    Wang, Hongyu; Zhang, Baomin; Zhao, Xun; Li, Cong; Lu, Cunyue

    2018-04-01

    Conventional stereo vision algorithms suffer from high levels of hardware resource utilization due to algorithm complexity, or poor levels of accuracy caused by inadequacies in the matching algorithm. To address these issues, we have proposed a stereo range-finding technique that produces an excellent balance between cost, matching accuracy and real-time performance, for power line inspection using UAV. This was achieved through the introduction of a special image preprocessing algorithm and a weighted local stereo matching algorithm, as well as the design of a corresponding hardware architecture. Stereo vision systems based on this technique have a lower level of resource usage and also a higher level of matching accuracy following hardware acceleration. To validate the effectiveness of our technique, a stereo vision system based on our improved algorithms were implemented using the Spartan 6 FPGA. In comparative experiments, it was shown that the system using the improved algorithms outperformed the system based on the unimproved algorithms, in terms of resource utilization and matching accuracy. In particular, Block RAM usage was reduced by 19%, and the improved system was also able to output range-finding data in real time.

  16. Accuracy and speed of orthographic processing in persons with developmental dyslexia.

    PubMed

    King, Wayne M; Lombardino, Linda L; Ahmed, Sarah

    2005-08-01

    A group of 39 persons (20 male and 19 female, 11.0 to 32.5 yr.) with developmental dyslexia and 42 controls (21 male and 21 female, 11.2 to 32.3 years) were compared on computerized tests of sight word reading, nonword decoding, and spelling recognition. The subjects with developmental dyslexia performed significantly slower and less accurately than controls on all tasks. Further, the effect size of the group differences was larger for the older group. Within-group analyses showed a significant difference by age group on accuracy. Only the control group showed a significant age difference between groups on response time. Mean accuracy and response times for the reading-disabled subjects resembled shifted versions of the control group means. These results agree with previous reports that phonological deficits persist for reading-disabled adults and suggest a test of whether the discrepancy between reading-disabled and typically achieving readers may actually increase across age groups.

  17. Effects of oncoming target velocities on rapid force production and accuracy of force production intensity and timing.

    PubMed

    Ohta, Yoichi

    2017-12-01

    The present study aimed to clarify the effects of oncoming target velocities on the ability of rapid force production and accuracy and variability of simultaneous control of both force production intensity and timing. Twenty male participants (age: 21.0 ± 1.4 years) performed rapid gripping with a handgrip dynamometer to coincide with the arrival of an oncoming target by using a horizontal electronic trackway. The oncoming target velocities were 4, 8, and 12 m · s -1 , which were randomly produced. The grip force required was 30% of the maximal voluntary contraction. Although the peak force (Pf) and rate of force development (RFD) increased with increasing target velocity, the value of the RFD to Pf ratio was constant across the 3 target velocities. The accuracy of both force production intensity and timing decreased at higher target velocities. Moreover, the intrapersonal variability in temporal parameters was lower in the fast target velocity condition, but constant variability in 3 target velocities was observed in force intensity parameters. These results suggest that oncoming target velocity does not intrinsically affect the ability for rapid force production. However, the oncoming target velocity affects accuracy and variability of force production intensity and timing during rapid force production.

  18. The effect of sequential exposure of color conditions on time and accuracy of graphic symbol location.

    PubMed

    Alant, Erna; Kolatsis, Anna; Lilienfeld, Margi

    2010-03-01

    An important aspect in AAC concerns the user's ability to locate an aided visual symbol on a communication display in order to facilitate meaningful interaction with partners. Recent studies have suggested that the use of different colored symbols may be influential in the visual search process, and that this, in turn will influence the speed and accuracy of symbol location. This study examined the role of color on rate and accuracy of identifying symbols on an 8-location overlay through the use of 3 color conditions (same, mixed and unique). Sixty typically developing preschool children were exposed to two different sequential exposures (Set 1 and Set 2). Participants searched for a target stimulus (either meaningful symbols or arbitrary forms) in a stimuli array. Findings indicated that the sequential exposures (orderings) impacted both time and accuracy for both types of symbols within specific instances.

  19. Comparison of Accuracy and Speed of Information Identification by Nonpathologists in Synoptic Reports With Different Formats.

    PubMed

    Renshaw, Andrew A; Gould, Edwin W

    2017-03-01

    - The College of American Pathologists requires synoptic reports for specific types of pathology reports. - To compare the accuracy and speed of information retrieval in synoptic reports of different formats. - We assessed the performance of 28 nonpathologists from 4 different types of users (cancer registrars, MDs, medical non-MDs, and nonmedical) at identifying specific information in various formatted synoptic reports, using a computerized quiz that measured both accuracy and speed. - There was no significant difference in the accuracy of data identification for any user group or in any format. While there were significant differences in raw time between users, these were eliminated when normalized times were used. Compared with the standard format of a required data element (RDE) and response on 1 line, both a list of responses without an RDE (21%, P < .001) and a paired response with more concise text (33%, P < .001) were significantly faster. In contrast, both the 2-line format (RDE header on one line, response indented on the second line) (12%, P < .001) and a report with the RDE response pairs in a random order were significantly slower (16%, P < .001). - There are significant differences in ease of use by nonpathologists between different synoptic report formats. Such information may be useful in deciding between different format options.

  20. Time-Resolved Intrafraction Target Translations and Rotations During Stereotactic Liver Radiation Therapy: Implications for Marker-based Localization Accuracy

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Bertholet, Jenny, E-mail: jennbe@rm.dk; Worm, Esben S.; Fledelius, Walther

    Purpose: Image guided liver stereotactic body radiation therapy (SBRT) often relies on implanted fiducial markers. The target localization accuracy decreases with increased marker-target distance. This may occur partly because of liver rotations. The aim of this study was to examine time-resolved translations and rotations of liver marker constellations and investigate if time-resolved intrafraction rotational corrections can improve localization accuracy in liver SBRT. Methods and Materials: Twenty-nine patients with 3 implanted markers received SBRT in 3 to 6 fractions. The time-resolved trajectory of each marker was estimated from the projections of 1 to 3 daily cone beam computed tomography scans andmore » used to calculate the translation and rotation of the marker constellation. In all cone beam computed tomography projections, the time-resolved position of each marker was predicted from the position of another surrogate marker by assuming that the marker underwent either (1) the same translation as the surrogate marker; or (2) the same translation as the surrogate marker corrected by the rotation of the marker constellation. The localization accuracy was quantified as the root-mean-square error (RMSE) between the estimated and the actual marker position. For comparison, the RMSE was also calculated when the marker's position was estimated as its mean position for all the projections. Results: The mean translational and rotational range (2nd-98th percentile) was 2.0 mm/3.9° (right-left), 9.2 mm/2.9° (superior-inferior), 4.0 mm/4.0° (anterior-posterior), and 10.5 mm (3-dimensional). Rotational corrections decreased the mean 3-dimensional RMSE from 0.86 mm to 0.54 mm (P<.001) and halved the RMSE increase per millimeter increase in marker distance. Conclusions: Intrafraction rotations during liver SBRT reduce the accuracy of marker-guided target localization. Rotational correction can improve the localization accuracy with a factor of approximately 2

  1. 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…

  2. Optimizing Tsunami Forecast Model Accuracy

    NASA Astrophysics Data System (ADS)

    Whitmore, P.; Nyland, D. L.; Huang, P. Y.

    2015-12-01

    Recent tsunamis provide a means to determine the accuracy that can be expected of real-time tsunami forecast models. Forecast accuracy using two different tsunami forecast models are compared for seven events since 2006 based on both real-time application and optimized, after-the-fact "forecasts". Lessons learned by comparing the forecast accuracy determined during an event to modified applications of the models after-the-fact provide improved methods for real-time forecasting for future events. Variables such as source definition, data assimilation, and model scaling factors are examined to optimize forecast accuracy. Forecast accuracy is also compared for direct forward modeling based on earthquake source parameters versus accuracy obtained by assimilating sea level data into the forecast model. Results show that including assimilated sea level data into the models increases accuracy by approximately 15% for the events examined.

  3. Phasic heart rate responses and cardiac cycle time in auditory choice reaction time.

    PubMed

    van der Molen, M W; Somsen, R J; Orlebeke, J F

    1983-01-01

    This study investigated the cardiovascular-behavioral interaction under short and long stimulus interval conditions. In addition, the cardiovascular-behavioral interaction was studied as affected by cardiac cycle duration. Fourteen subjects performed a choice reaction time (RT) task employing a mixed speed-accuracy tradeoff design in which reactions were paced to coincide with a signal that occurs randomly at either 200 or 500 msec after the reaction stimulus. The preparatory interval between a warning stimulus and a lead-reaction stimulus complex was also varied (2 vs. 4.5 sec). Anticipatory deceleration occurred within the 4.5 sec interval but not in the 2 sec interval. The depth of anticipatory deceleration did not discriminate between fast and slow reactions; but an earlier shift from deceleration to acceleration was associated with fast reactions. The effect of stimulus timing relative to the R-wave of the electrocardiogram was also analysed. Meaningful stimuli tended to produce cardiac slowing as previously described in the literature. Early occurring stimuli prolong the cycle of their occurrence more than late occurring stimuli. The later prolong the subsequent cycle. Cardiac cycle time effects were absent for unattended stimuli. The results of anticipatory deceleration suggested that the depth of deceleration was regulated by time-uncertainty and speed-accuracy criterion.

  4. Changing behavior and accuracy with time on task in mammography screening

    NASA Astrophysics Data System (ADS)

    Taylor-Phillips, Sian; Jenkinson, David; Stinton, Chris; Wallis, Matthew G.; Clarke, Aileen

    2017-03-01

    Background: The vigilance decrement and prevalence effect both describe changes to speed and accuracy with time on task. Whilst there is much laboratory based research on these effects, little is known about whether they occur in real world mammography practice. Methods: The Changing Case Order to Optimise Patterns of Performance in Screening (CO-OPS) trial randomised 37,724 batches containing 1.2 million women attending breast screening to intervention or control (222,208 from the Midlands of England). In the control arm the batch was examined in the same order by both readers, in the intervention arm it was examined in a different order by both readers. Time taken, recall decision by both readers, and cancers detected were recorded for each case, and used to examine patterns of performance with time on task. Results: 49,575 women were recalled and 10,484 had cancer detected. Median time taken to examine each case was 35 seconds (out of cases where time taken was 10 minutes or less). The intervention did not affect overall cancer detection rates or recall rates. A more detailed analysis of the Midlands data indicates cancer detection rate did not change when reading up to 60 cases in a batch, but recall rate reduced. Time taken per case reduced with time on task, from a median 41 seconds when examining the second case in the batch to 28.5 seconds examining the 60th case. Conclusion: Reader behavior and performance systematically changes with time on task in breast screening.

  5. Accuracy and Numerical Stabilty Analysis of Lattice Boltzmann Method with Multiple Relaxation Time for Incompressible Flows

    NASA Astrophysics Data System (ADS)

    Pradipto; Purqon, Acep

    2017-07-01

    Lattice Boltzmann Method (LBM) is the novel method for simulating fluid dynamics. Nowadays, the application of LBM ranges from the incompressible flow, flow in the porous medium, until microflows. The common collision model of LBM is the BGK with a constant single relaxation time τ. However, BGK suffers from numerical instabilities. These instabilities could be eliminated by implementing LBM with multiple relaxation time. Both of those scheme have implemented for incompressible 2 dimensions lid-driven cavity. The stability analysis has done by finding the maximum Reynolds number and velocity for converged simulations. The accuracy analysis is done by comparing the velocity profile with the benchmark results from Ghia, et al and calculating the net velocity flux. The tests concluded that LBM with MRT are more stable than BGK, and have a similar accuracy. The maximum Reynolds number that converges for BGK is 3200 and 7500 for MRT respectively.

  6. Selective effect of physical fatigue on motor imagery accuracy.

    PubMed

    Di Rienzo, Franck; Collet, Christian; Hoyek, Nady; Guillot, Aymeric

    2012-01-01

    While the use of motor imagery (the mental representation of an action without overt execution) during actual training sessions is usually recommended, experimental studies examining the effect of physical fatigue on subsequent motor imagery performance are sparse and yielded divergent findings. Here, we investigated whether physical fatigue occurring during an intense sport training session affected motor imagery ability. Twelve swimmers (nine males, mean age 15.5 years) conducted a 45 min physically-fatiguing protocol where they swam from 70% to 100% of their maximal aerobic speed. We tested motor imagery ability immediately before and after fatigue state. Participants randomly imagined performing a swim turn using internal and external visual imagery. Self-reports ratings, imagery times and electrodermal responses, an index of alertness from the autonomic nervous system, were the dependent variables. Self-reports ratings indicated that participants did not encounter difficulty when performing motor imagery after fatigue. However, motor imagery times were significantly shortened during posttest compared to both pretest and actual turn times, thus indicating reduced timing accuracy. Looking at the selective effect of physical fatigue on external visual imagery did not reveal any difference before and after fatigue, whereas significantly shorter imagined times and electrodermal responses (respectively 15% and 48% decrease, p<0.001) were observed during the posttest for internal visual imagery. A significant correlation (r=0.64; p<0.05) was observed between motor imagery vividness (estimated through imagery questionnaire) and autonomic responses during motor imagery after fatigue. These data support that unlike local muscle fatigue, physical fatigue occurring during intense sport training sessions is likely to affect motor imagery accuracy. These results might be explained by the updating of the internal representation of the motor sequence, due to temporary

  7. Selective Effect of Physical Fatigue on Motor Imagery Accuracy

    PubMed Central

    Di Rienzo, Franck; Collet, Christian; Hoyek, Nady; Guillot, Aymeric

    2012-01-01

    While the use of motor imagery (the mental representation of an action without overt execution) during actual training sessions is usually recommended, experimental studies examining the effect of physical fatigue on subsequent motor imagery performance are sparse and yielded divergent findings. Here, we investigated whether physical fatigue occurring during an intense sport training session affected motor imagery ability. Twelve swimmers (nine males, mean age 15.5 years) conducted a 45 min physically-fatiguing protocol where they swam from 70% to 100% of their maximal aerobic speed. We tested motor imagery ability immediately before and after fatigue state. Participants randomly imagined performing a swim turn using internal and external visual imagery. Self-reports ratings, imagery times and electrodermal responses, an index of alertness from the autonomic nervous system, were the dependent variables. Self-reports ratings indicated that participants did not encounter difficulty when performing motor imagery after fatigue. However, motor imagery times were significantly shortened during posttest compared to both pretest and actual turn times, thus indicating reduced timing accuracy. Looking at the selective effect of physical fatigue on external visual imagery did not reveal any difference before and after fatigue, whereas significantly shorter imagined times and electrodermal responses (respectively 15% and 48% decrease, p<0.001) were observed during the posttest for internal visual imagery. A significant correlation (r = 0.64; p<0.05) was observed between motor imagery vividness (estimated through imagery questionnaire) and autonomic responses during motor imagery after fatigue. These data support that unlike local muscle fatigue, physical fatigue occurring during intense sport training sessions is likely to affect motor imagery accuracy. These results might be explained by the updating of the internal representation of the motor sequence, due to temporary

  8. 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

  9. 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

  10. Relationship between cutoff frequency and accuracy in time-interval photon statistics applied to oscillating signals

    NASA Astrophysics Data System (ADS)

    Rebolledo, M. A.; Martinez-Betorz, J. A.

    1989-04-01

    In this paper the accuracy in the determination of the period of an oscillating signal, when obtained from the photon statistics time-interval probability, is studied as a function of the precision (the inverse of the cutoff frequency of the photon counting system) with which time intervals are measured. The results are obtained by means of an experiment with a square-wave signal, where the Fourier or square-wave transforms of the time-interval probability are measured. It is found that for values of the frequency of the signal near the cutoff frequency the errors in the period are small.

  11. Predictive accuracy of changes in transvaginal sonographic cervical length over time for preterm birth: a systematic review and metaanalysis.

    PubMed

    Conde-Agudelo, Agustin; Romero, Roberto

    2015-12-01

    To determine the accuracy of changes in transvaginal sonographic cervical length over time in predicting preterm birth in women with singleton and twin gestations. PubMed, Embase, Cinahl, Lilacs, and Medion (all from inception to June 30, 2015), bibliographies, Google scholar, and conference proceedings. Cohort or cross-sectional studies reporting on the predictive accuracy for preterm birth of changes in cervical length over time. Two reviewers independently selected studies, assessed the risk of bias, and extracted the data. Summary receiver-operating characteristic curves, pooled sensitivities and specificities, and summary likelihood ratios were generated. Fourteen studies met the inclusion criteria, of which 7 provided data on singleton gestations (3374 women) and 8 on twin gestations (1024 women). Among women with singleton gestations, the shortening of cervical length over time had a low predictive accuracy for preterm birth at <37 and <35 weeks of gestation with pooled sensitivities and specificities, and summary positive and negative likelihood ratios ranging from 49% to 74%, 44% to 85%, 1.3 to 4.1, and 0.3 to 0.7, respectively. In women with twin gestations, the shortening of cervical length over time had a low to moderate predictive accuracy for preterm birth at <34, <32, <30, and <28 weeks of gestation with pooled sensitivities and specificities, and summary positive and negative likelihood ratios ranging from 47% to 73%, 84% to 89%, 3.8 to 5.3, and 0.3 to 0.6, respectively. There were no statistically significant differences between the predictive accuracies for preterm birth of cervical length shortening over time and the single initial and/or final cervical length measurement in 8 of 11 studies that provided data for making these comparisons. In the largest and highest-quality study, a single measurement of cervical length obtained at 24 or 28 weeks of gestation was significantly more predictive of preterm birth than any decrease in cervical length

  12. 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.

  13. Fixed-ratio discrimination: effects of response-produced blackouts1

    PubMed Central

    Lydersen, Tore; Crossman, E. K.

    1974-01-01

    For three pigeons, reinforcement depended upon a left side-key response after execution of a fixed ratio 10 on the center key, and upon a right side-key response after fixed ratio 20. Each response during the fixed ratios produced a 0.5-sec blackout. The time between the first and last response in fixed ratio 10 was then equated with the time between the first and last response in fixed ratio 20 by increasing the blackout duration. The accuracy of side-key choice was disrupted, thereby suggesting that time, rather than number of responses, controlled choice responding. When the time between the first and last response was equated during both ratios, asymptotic accuracy was approximately equal to (two birds) or somewhat higher than (one bird) that obtained previously. The results of probes with intermediate fixed ratios and blackouts suggested that control of side-key choice had transferred from the time between the first and last response in ratios to blackout duration. PMID:16811819

  14. Massive metrology using fast e-beam technology improves OPC model accuracy by >2x at faster turnaround time

    NASA Astrophysics Data System (ADS)

    Zhao, Qian; Wang, Lei; Wang, Jazer; Wang, ChangAn; Shi, Hong-Fei; Guerrero, James; Feng, Mu; Zhang, Qiang; Liang, Jiao; Guo, Yunbo; Zhang, Chen; Wallow, Tom; Rio, David; Wang, Lester; Wang, Alvin; Wang, Jen-Shiang; Gronlund, Keith; Lang, Jun; Koh, Kar Kit; Zhang, Dong Qing; Zhang, Hongxin; Krishnamurthy, Subramanian; Fei, Ray; Lin, Chiawen; Fang, Wei; Wang, Fei

    2018-03-01

    Classical SEM metrology, CD-SEM, uses low data rate and extensive frame-averaging technique to achieve high-quality SEM imaging for high-precision metrology. The drawbacks include prolonged data collection time and larger photoresist shrinkage due to excess electron dosage. This paper will introduce a novel e-beam metrology system based on a high data rate, large probe current, and ultra-low noise electron optics design. At the same level of metrology precision, this high speed e-beam metrology system could significantly shorten data collection time and reduce electron dosage. In this work, the data collection speed is higher than 7,000 images per hr. Moreover, a novel large field of view (LFOV) capability at high resolution was enabled by an advanced electron deflection system design. The area coverage by LFOV is >100x larger than classical SEM. Superior metrology precision throughout the whole image has been achieved, and high quality metrology data could be extracted from full field. This new capability on metrology will further improve metrology data collection speed to support the need for large volume of metrology data from OPC model calibration of next generation technology. The shrinking EPE (Edge Placement Error) budget places more stringent requirement on OPC model accuracy, which is increasingly limited by metrology errors. In the current practice of metrology data collection and data processing to model calibration flow, CD-SEM throughput becomes a bottleneck that limits the amount of metrology measurements available for OPC model calibration, impacting pattern coverage and model accuracy especially for 2D pattern prediction. To address the trade-off in metrology sampling and model accuracy constrained by the cycle time requirement, this paper employs the high speed e-beam metrology system and a new computational software solution to take full advantage of the large volume data and significantly reduce both systematic and random metrology errors. The

  15. 29 CFR 1610.9 - Responses: timing.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 29 Labor 4 2013-07-01 2013-07-01 false Responses: timing. 1610.9 Section 1610.9 Labor Regulations... Disclosure Under 5 U.S.C. 552 § 1610.9 Responses: timing. (a) The EEOC utilizes a multitrack system for..., the complex track, or the expedited track. EEOC distinguishes between simple and complex track...

  16. 29 CFR 1610.9 - Responses: timing.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 29 Labor 4 2014-07-01 2014-07-01 false Responses: timing. 1610.9 Section 1610.9 Labor Regulations... Disclosure Under 5 U.S.C. 552 § 1610.9 Responses: timing. (a) The EEOC utilizes a multitrack system for..., the complex track, or the expedited track. EEOC distinguishes between simple and complex track...

  17. Modeling Fan Effects on the Time Course of Associative Recognition

    PubMed Central

    Schneider, Darryl W.; Anderson, John R.

    2011-01-01

    We investigated the time course of associative recognition using the response signal procedure, whereby a stimulus is presented and followed after a variable lag by a signal indicating that an immediate response is required. More specifically, we examined the effects of associative fan (the number of associations that an item has with other items in memory) on speed–accuracy tradeoff functions obtained in a previous response signal experiment involving briefly studied materials and in a new experiment involving well-learned materials. High fan lowered asymptotic accuracy or the rate of rise in accuracy across lags, or both. We developed an Adaptive Control of Thought–Rational (ACT-R) model for the response signal procedure to explain these effects. The model assumes that high fan results in weak associative activation that slows memory retrieval, thereby decreasing the probability that retrieval finishes in time and producing a speed–accuracy tradeoff function. The ACT-R model provided an excellent account of the data, yielding quantitative fits that were as good as those of the best descriptive model for response signal data. PMID:22197797

  18. Disfluency prompts analytic thinking--but not always greater accuracy: response to Thompson et al. (2013).

    PubMed

    Alter, Adam L; Oppenheimer, Daniel M; Epley, Nicholas

    2013-08-01

    In this issue of Cognition, Thompson and her colleagues challenge the results from a paper we published several years ago (Alter, Oppenheimer, Epley, & Eyre, 2007). That paper demonstrated that metacognitive difficulty or disfluency can trigger more analytical thinking as measured by accuracy on several reasoning tasks. In their experiments, Thompson et al. find evidence that people process information more deeply-but not necessarily more accurately-when they experience disfluency. These results are consistent with our original theorizing, but the authors misinterpret it as counter-evidence because they suggest that accuracy (and even confidence) is a measure of deeper processing rather than a contingent outcome of such processing. We further suggest that Thompson et al. err when they discriminate between "perceptual fluency" and "answer fluency," the former of which is an element of the latter. Thompson et al. advance research by adding reaction time as a measure of deeper cognitive processing, but we caution against misinterpreting the meaning of accuracy. Copyright © 2013 Elsevier B.V. All rights reserved.

  19. Accuracy of GPS time transfer verified by closure around the world

    NASA Technical Reports Server (NTRS)

    Lewandowski, Wlodimierz W.; Petit, Gerard; Thomas, Claudine

    1992-01-01

    The precision of time transfer over intercontinental distances by the Global Positioning System common-view method, using measurements of ionospheric delays, precise ephemerides provided by the Defense Mapping Agency (DMA) and a consistent set of antenna coordinates, reaches 3 to 4 ns for a single 13-minute measurement, and decreases to 2 ns when averaging several measurements over the period of one day. It is thought that even this level of precision can be bettered by improving the ionospheric measurements, the ephemerides of satellites, and the antenna coordinates. In the same conditions, an estimation of the accuracy is attained by using three intercontinental links encircling the Earth to establish a closure condition; the three independent links should add to zero. We have computed such a closure condition over a period of 13 months using data recorded at the Paris Observatory, at the Communications Research Laboratory in Tokyo, and at the National Institute for Standards and Technology in Boulder, Colorado. The closure condition is verified to within a few nanoseconds, but a bias, varying with time, can be detected.

  20. 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…

  1. Alcoholic hepatitis histological score has high accuracy to predict 90-day mortality and response to steroids.

    PubMed

    Andrade, Patrícia; Silva, Marco; Rodrigues, Susana; Lopes, Joanne; Lopes, Susana; Macedo, Guilherme

    2016-06-01

    A histological classification system (AHHS) has been recently proposed to predict 90-day mortality in patients with alcoholic hepatitis (AH). We analyzed the spectrum of histological features in patients with AH and assessed the ability of AHHS for predicting both response to steroids and 90-day mortality. Retrospective study of patients admitted to our tertiary centre between 2010 and 2014 with biopsy-proven AH. Histological features were analyzed and AHHS value was calculated. Kaplan-Meyer curves were calculated to assess the ability of AHHS to predict response to steroids and 90-day mortality. We included 34 patients (70.6% men, mean age 48.5±8.9 years). Transjugular liver biopsy was performed 3.5±2.9 days after admission. Presence of bilirubinostasis (p=0.049), degree of bilirubinostasis (p<0.001), absence of megamitochondria (p<0.001) and degree of polymorphonuclear infiltration (p=0.018) were significantly associated with higher mortality at 90 days. Patients who responded to steroids had a significantly lower AHHS value than non-responders (5.4±0.9 vs 8.1±1.1, p=0.003). AAHS value was significantly higher in patients who died compared to patients who survived at 90 days (9.0±0.7 vs 5.0±0.9, p<0.001). AHHS predicted response to steroids [AUROC 0.90 (CI95% 0.742-1.000), p=0.004] and 90-day mortality [AUROC 1.0 (CI95% 1.0-1.0), p<0.001] with high accuracy. In this cohort of patients, presence and degree of bilirubinostasis, absence of megamitochondria and degree of PMN infiltration were significantly associated with 90-day mortality. AHHS had a high accuracy for predicting response to steroids and 90-day mortality in this cohort of patients. Copyright © 2016 Editrice Gastroenterologica Italiana S.r.l. Published by Elsevier Ltd. All rights reserved.

  2. Improved accuracy of co-morbidity coding over time after the introduction of ICD-10 administrative data

    PubMed Central

    2011-01-01

    Background Co-morbidity information derived from administrative data needs to be validated to allow its regular use. We assessed evolution in the accuracy of coding for Charlson and Elixhauser co-morbidities at three time points over a 5-year period, following the introduction of the International Classification of Diseases, 10th Revision (ICD-10), coding of hospital discharges. Methods Cross-sectional time trend evaluation study of coding accuracy using hospital chart data of 3'499 randomly selected patients who were discharged in 1999, 2001 and 2003, from two teaching and one non-teaching hospital in Switzerland. We measured sensitivity, positive predictive and Kappa values for agreement between administrative data coded with ICD-10 and chart data as the 'reference standard' for recording 36 co-morbidities. Results For the 17 the Charlson co-morbidities, the sensitivity - median (min-max) - was 36.5% (17.4-64.1) in 1999, 42.5% (22.2-64.6) in 2001 and 42.8% (8.4-75.6) in 2003. For the 29 Elixhauser co-morbidities, the sensitivity was 34.2% (1.9-64.1) in 1999, 38.6% (10.5-66.5) in 2001 and 41.6% (5.1-76.5) in 2003. Between 1999 and 2003, sensitivity estimates increased for 30 co-morbidities and decreased for 6 co-morbidities. The increase in sensitivities was statistically significant for six conditions and the decrease significant for one. Kappa values were increased for 29 co-morbidities and decreased for seven. Conclusions Accuracy of administrative data in recording clinical conditions improved slightly between 1999 and 2003. These findings are of relevance to all jurisdictions introducing new coding systems, because they demonstrate a phenomenon of improved administrative data accuracy that may relate to a coding 'learning curve' with the new coding system. PMID:21849089

  3. Improved accuracy of co-morbidity coding over time after the introduction of ICD-10 administrative data.

    PubMed

    Januel, Jean-Marie; Luthi, Jean-Christophe; Quan, Hude; Borst, François; Taffé, Patrick; Ghali, William A; Burnand, Bernard

    2011-08-18

    Co-morbidity information derived from administrative data needs to be validated to allow its regular use. We assessed evolution in the accuracy of coding for Charlson and Elixhauser co-morbidities at three time points over a 5-year period, following the introduction of the International Classification of Diseases, 10th Revision (ICD-10), coding of hospital discharges. Cross-sectional time trend evaluation study of coding accuracy using hospital chart data of 3'499 randomly selected patients who were discharged in 1999, 2001 and 2003, from two teaching and one non-teaching hospital in Switzerland. We measured sensitivity, positive predictive and Kappa values for agreement between administrative data coded with ICD-10 and chart data as the 'reference standard' for recording 36 co-morbidities. For the 17 the Charlson co-morbidities, the sensitivity - median (min-max) - was 36.5% (17.4-64.1) in 1999, 42.5% (22.2-64.6) in 2001 and 42.8% (8.4-75.6) in 2003. For the 29 Elixhauser co-morbidities, the sensitivity was 34.2% (1.9-64.1) in 1999, 38.6% (10.5-66.5) in 2001 and 41.6% (5.1-76.5) in 2003. Between 1999 and 2003, sensitivity estimates increased for 30 co-morbidities and decreased for 6 co-morbidities. The increase in sensitivities was statistically significant for six conditions and the decrease significant for one. Kappa values were increased for 29 co-morbidities and decreased for seven. Accuracy of administrative data in recording clinical conditions improved slightly between 1999 and 2003. These findings are of relevance to all jurisdictions introducing new coding systems, because they demonstrate a phenomenon of improved administrative data accuracy that may relate to a coding 'learning curve' with the new coding system.

  4. Accuracy of electronic implant torque controllers following time in clinical service.

    PubMed

    Mitrani, R; Nicholls, J I; Phillips, K M; Ma, T

    2001-01-01

    Tightening of the screws in implant-supported restorations has been reported to be problematic, in that if the applied torque is too low, screw loosening occurs. If the torque is too high, then screw fracture can take place. Thus, accuracy of the torque driver is of the utmost importance. This study evaluated 4 new electronic torque drivers (controls) and 10 test electronic torque drivers, which had been in clinical service for a minimum of 5 years. Torque values of the test drivers were measured and were compared with the control values using a 1-way analysis of variance. Torque delivery accuracy was measured using a technique that simulated the clinical situation. In vivo, the torque driver turns the screw until the selected tightening torque is reached. In this laboratory experiment, an implant, along with an attached abutment and abutment gold screw, was held firmly in a Tohnichi torque gauge. Calibration accuracy for the Tohnichi is +/- 3% of the scale value. During torque measurement, the gold screw turned a minimum of 180 degrees before contact was made between the screw and abutment. Three torque values (10, 20, and 32 N-cm) were evaluated, at both high- and low-speed settings. The recorded torque measurements indicated that the 10 test electronic torque drivers maintained a torque delivery accuracy equivalent to the 4 new (unused) units. Judging from the torque output values obtained from the 10 test units, the clinical use of the electronic torque driver suggests that accuracy did not change significantly over the 5-year period of clinical service.

  5. Influence of time of placement of investments for burnout and the type of rings being used on the casting accuracy.

    PubMed

    Shah, Shabir A; Naqash, Talib Amin; Padmanabhan, T V; Subramanium; Lambodaran; Nazir, Shazana

    2014-03-01

    The sole objective of casting procedure is to provide a metallic duplication of missing tooth structure, with as great accuracy as possible. The ability to produce well fitting castings require strict adherence to certain fundamentals. A study was undertaken to comparatively evaluate the effect on casting accuracy by subjecting the invested wax patterns to burnout after different time intervals. The effect on casting accuracy using metal ring into a pre heated burnout furnace and using split ring was also carried. The readings obtained were tabulated and subjected to statistical analysis.

  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. Increasing Accuracy in Computed Inviscid Boundary Conditions

    NASA Technical Reports Server (NTRS)

    Dyson, Roger

    2004-01-01

    A technique has been devised to increase the accuracy of computational simulations of flows of inviscid fluids by increasing the accuracy with which surface boundary conditions are represented. This technique is expected to be especially beneficial for computational aeroacoustics, wherein it enables proper accounting, not only for acoustic waves, but also for vorticity and entropy waves, at surfaces. Heretofore, inviscid nonlinear surface boundary conditions have been limited to third-order accuracy in time for stationary surfaces and to first-order accuracy in time for moving surfaces. For steady-state calculations, it may be possible to achieve higher accuracy in space, but high accuracy in time is needed for efficient simulation of multiscale unsteady flow phenomena. The present technique is the first surface treatment that provides the needed high accuracy through proper accounting of higher-order time derivatives. The present technique is founded on a method known in art as the Hermitian modified solution approximation (MESA) scheme. This is because high time accuracy at a surface depends upon, among other things, correction of the spatial cross-derivatives of flow variables, and many of these cross-derivatives are included explicitly on the computational grid in the MESA scheme. (Alternatively, a related method other than the MESA scheme could be used, as long as the method involves consistent application of the effects of the cross-derivatives.) While the mathematical derivation of the present technique is too lengthy and complex to fit within the space available for this article, the technique itself can be characterized in relatively simple terms: The technique involves correction of surface-normal spatial pressure derivatives at a boundary surface to satisfy the governing equations and the boundary conditions and thereby achieve arbitrarily high orders of time accuracy in special cases. The boundary conditions can now include a potentially infinite number

  8. Aberrant connections between climbing fibres and Purkinje cells induce alterations in the timing of an instrumental response in the rat.

    PubMed

    Gaytán-Tocavén, Lorena; López-Vázquez, Miguel Ángel; Guevara, Miguel Ángel; Olvera-Cortés, María Esther

    2017-09-01

    Cerebellar participation in timing and sensory-motor sequences has been supported by several experimental and clinical studies. A relevant role of the cerebellum in timing of conditioned responses in the range of milliseconds has been demonstrated, but less is known regarding the role of the cerebellum in supra-second timing of operant responses. A dissociated role of the cerebellum and striatum in timing in the millisecond and second range had been reported, respectively. The climbing fibre-Purkinje cell synapse is crucial in timing models; thus, the aberrant connection between these cellular elements is a suitable model for evaluating the contribution of the cerebellum in timing in the supra-second range. The aberrant connection between climbing fibres and Purkinje cells was induced by administration of the antagonist of NMDA receptors MK-801 to Sprague-Dawley rats at postnatal days 7-14. The timing of an operant response with two fixed intervals (5 and 8 s) and egocentric sequential learning was evaluated in 60-day-old adult rats. The aberrant connections caused a reduced accuracy in the timing of the instrumental response that was more evident in the 8-s interval and a reduced number of successive correct responses (responses emitted in the correct second without any other response between them) in the 8-s interval. In addition, an inability to incorporate new information in a sequence previously learned in egocentric-based sequence learning was apparent in rats with aberrant CF-PC synapses. These results support a relevant role for the cerebellum in the fine-tuning of the timing of operant responses in the supra-second range.

  9. Effect of loudness on reaction time and response force in different motor tasks.

    PubMed

    Jaśkowski, Piotr; Włodarczyk, Dariusz

    2005-12-01

    Van der Molen and Keuss, in 1979 and 1981, showed that paradoxically long reaction times occur with extremely strong auditory stimuli when the task is difficult, e.g., choice-by-location or Simon paradigm. It was argued that this paradoxical behavior of RT is due to active inhibition of an arousal-dependent bypassing mechanism to prevent false responses. As the peak force, i.e., maximal force exerted by participants on a response key, is considered to be related to immediate arousal, we predicted that for extremely loud stimuli and for difficult tasks, lengthening of RT should be associated with reduction of peak force. Moreover, these effects should be enhanced when emphasis is on accuracy rather than speed. Although the relation between RT and intensity depended on task difficulty, no increase in RT was found for the loudest tones. Moreover, peak force increased monotonically with loudness, showing no tendency to be suppressed for loudest tones and difficult tasks.

  10. 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

    2017-06-01

    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.

  11. Cognitive Reflection, Decision Biases, and Response Times.

    PubMed

    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.

  12. Slower is not always better: Response-time evidence clarifies the limited role of miserly information processing in the Cognitive Reflection Test

    PubMed Central

    Pitchford, Melanie; Ball, Linden J.; Hunt, Thomas E.; Steel, Richard

    2017-01-01

    We report a study examining the role of ‘cognitive miserliness’ as a determinant of poor performance on the standard three-item Cognitive Reflection Test (CRT). The cognitive miserliness hypothesis proposes that people often respond incorrectly on CRT items because of an unwillingness to go beyond default, heuristic processing and invest time and effort in analytic, reflective processing. Our analysis (N = 391) focused on people’s response times to CRT items to determine whether predicted associations are evident between miserly thinking and the generation of incorrect, intuitive answers. Evidence indicated only a weak correlation between CRT response times and accuracy. Item-level analyses also failed to demonstrate predicted response-time differences between correct analytic and incorrect intuitive answers for two of the three CRT items. We question whether participants who give incorrect intuitive answers on the CRT can legitimately be termed cognitive misers and whether the three CRT items measure the same general construct. PMID:29099840

  13. 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.

  14. Colored noise effects on batch attitude accuracy estimates

    NASA Technical Reports Server (NTRS)

    Bilanow, Stephen

    1991-01-01

    The effects of colored noise on the accuracy of batch least squares parameter estimates with applications to attitude determination cases are investigated. The standard approaches used for estimating the accuracy of a computed attitude commonly assume uncorrelated (white) measurement noise, while in actual flight experience measurement noise often contains significant time correlations and thus is colored. For example, horizon scanner measurements from low Earth orbit were observed to show correlations over many minutes in response to large scale atmospheric phenomena. A general approach to the analysis of the effects of colored noise is investigated, and interpretation of the resulting equations provides insight into the effects of any particular noise color and the worst case noise coloring for any particular parameter estimate. It is shown that for certain cases, the effects of relatively short term correlations can be accommodated by a simple correction factor. The errors in the predicted accuracy assuming white noise and the reduced accuracy due to the suboptimal nature of estimators that do not take into account the noise color characteristics are discussed. The appearance of a variety of sample noise color characteristics are demonstrated through simulation, and their effects are discussed for sample estimation cases. Based on the analysis, options for dealing with the effects of colored noise are discussed.

  15. 40 CFR 1066.245 - Response time verification.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... dynamometer's automated process to verify response time. Perform this test at two different inertia settings... observed settling response time must be less than 100 milliseconds for each inertia setting. ER15SE11.085 ...

  16. 40 CFR 1066.245 - Response time verification.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... dynamometer's automated process to verify response time. Perform this test at two different inertia settings... observed settling response time must be less than 100 milliseconds for each inertia setting. ER15SE11.085 ...

  17. A Box-Cox normal model for response times.

    PubMed

    Klein Entink, R H; van der Linden, W J; Fox, J-P

    2009-11-01

    The log-transform has been a convenient choice in response time modelling on test items. However, motivated by a dataset of the Medical College Admission Test where the lognormal model violated the normality assumption, the possibilities of the broader class of Box-Cox transformations for response time modelling are investigated. After an introduction and an outline of a broader framework for analysing responses and response times simultaneously, the performance of a Box-Cox normal model for describing response times is investigated using simulation studies and a real data example. A transformation-invariant implementation of the deviance information criterium (DIC) is developed that allows for comparing model fit between models with different transformation parameters. Showing an enhanced description of the shape of the response time distributions, its application in an educational measurement context is discussed at length.

  18. Time response for sensor sensed to actuator response for mobile robotic system

    NASA Astrophysics Data System (ADS)

    Amir, N. S.; Shafie, A. A.

    2017-11-01

    Time and performance of a mobile robot are very important in completing the tasks given to achieve its ultimate goal. Tasks may need to be done within a time constraint to ensure smooth operation of a mobile robot and can result in better performance. The main purpose of this research was to improve the performance of a mobile robot so that it can complete the tasks given within time constraint. The problem that is needed to be solved is to minimize the time interval between sensor detection and actuator response. The research objective is to analyse the real time operating system performance of sensors and actuators on one microcontroller and on two microcontroller for a mobile robot. The task for a mobile robot for this research is line following with an obstacle avoidance. Three runs will be carried out for the task and the time between the sensors senses to the actuator responses were recorded. Overall, the results show that two microcontroller system have better response time compared to the one microcontroller system. For this research, the average difference of response time is very important to improve the internal performance between the occurrence of a task, sensors detection, decision making and actuator response of a mobile robot. This research helped to develop a mobile robot with a better performance and can complete task within the time constraint.

  19. 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.

  20. 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

  1. Accuracy, reliability, and timing of visual evaluations of decay in fresh-cut lettuce

    PubMed Central

    Hayes, Ryan J.

    2018-01-01

    Visual assessments are used for evaluating the quality of food products, such as fresh-cut lettuce packaged in bags with modified atmosphere. We have compared the accuracy and the reliability of visual evaluations of decay on fresh-cut lettuce performed with experienced and inexperienced raters. In addition, we have analyzed decay data from over 4.5 thousand bags to determine the optimum timing for evaluations to detect differences among accessions. Lin’s concordance coefficient (ρc) that takes into consideration both the closeness of the data and the conformance to the identity line showed high repeatability (intra-rater reliability, ρc = 0.97), reproducibility (inter-rater reliability, ρc = 0.92), and accuracy (ρc = 0.96) for experienced raters. Inexperienced raters did not perform as well and their ratings showed decreased repeatability (ρc = 0.93), but even larger reduction in reproducibility (ρc = 0.80) and accuracy (ρc = 0.90). We have detected that 5.3% of ratings were outside of the 95% limits of agreement. These under- or overestimates were predominantly found for bags with intermediate levels of decay, which corresponds to the middle of the rating scale. This occurs because intermediate amounts of decay are more difficult to discriminate than extremes. The frequencies of aberrant ratings for experienced raters ranged from 0.6% to 4.4% (mean = 2.1%), for inexperienced raters the frequencies were substantially higher, ranging from 6.1% to 15.6% (mean = 9.4%). Therefore, we recommend that new raters receive training that includes practical examples in this range of decay, use of standard area diagrams, and continuing interaction with experienced raters (consultation during actual rating). Very high agreement among experienced raters indicate that visual ratings can be successfully used for evaluations of decay, until a more objective, rapid, and affordable method is developed. We recommend evaluating samples at multiple time points until 42 days

  2. Psychological counseling and accuracy of memory for child sexual abuse.

    PubMed

    Goodman, Gail S; Goldfarb, Deborah; Quas, Jodi A; Lyon, Alexandra

    2017-12-01

    Tens of thousands of child sexual abuse (CSA) cases are reported to authorities annually. Although some of the child victims obtain psychological counseling or therapy, controversy exists about the potential consequences for the accuracy of victims' memory of CSA, both in childhood and adulthood. Yet, delaying needed therapeutic intervention may have detrimental effects on the victims' well-being and recovery. To address this controversy, this study examined whether psychological counseling during a CSA prosecution predicts accuracy or inaccuracy of long-term memory for CSA. Participants (N = 71) were CSA victims who took part in a longitudinal study of memory and legal involvement. Data regarding participants' counseling attendance during the prosecution and details of their CSA cases were gathered throughout legal involvement and shortly thereafter (Time 1). Ten to 16 years later (Time 2), participants were questioned about a range of topics, including the alleged abuse. Time 1 counseling attendance significantly predicted more correct answers to abuse-related questions and (for corroborated cases) fewer overreporting responses at Time 2. Counseling was unrelated to underreporting responses. These results held even with other potential influences, such as abuse severity, victim-defendant relationship, posttraumatic stress disorder criteria met, testifying in the case, and delay, were statistically controlled. Although further research is needed, this study provides evidence that psychological counseling received by CSA victims during or shortly after prosecutions may improve later memory for abuse-related information. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  3. Responsive Hydrogel-based Photonic Nanochains for Microenvironment Sensing and Imaging in Real Time and High Resolution.

    PubMed

    Luo, Wei; Cui, Qian; Fang, Kai; Chen, Ke; Ma, Huiru; Guan, Jianguo

    2018-01-17

    Microenvironment sensing and imaging are of importance in microscale zones like microreactors, microfluidic systems, and biological cells. But they are so far implemented only based on chemical colors from dyes or quantum dots, which suffered either from photobleaching, quenching, or photoblinking behaviors, or from limited color gamut. In contrast, structural colors from hydrogel-based photonic crystals (PCs) may be stable and tunable in the whole visible spectrum by diffraction peak shift, facilitating the visual detection with high accuracy. However, the current hydrogel-based PCs are all inappropriate for microscale detection due to the bulk size. Here we demonstrate the smallest hydrogel-based PCs, responsive hydrogel-based photonic nanochains with high-resolution and real-time response, by developing a general hydrogen bond-guided template polymerization method. A variety of mechanically separated stimuli-responsive hydrogel-based photonic nanochains have been obtained in a large scale including those responding to pH, solvent, and temperature. Each of them has a submicrometer diameter and is composed of individual one-dimensional periodic structure of magnetic particles locked by a tens-of-nanometer-thick peapod-like responsive hydrogel shell. Taking the pH-responsive hydrogel-based photonic nanochains, for example, pH-induced hydrogel volume change notably alters the nanochain length, resulting in a significant variation of the structural color. The submicrometer size endows the nanochains with improved resolution and response time by 2-3 orders of magnitude than the previous counterparts. Our results for the first time validate the feasibility of using structural colors for microenvironment sensing and imaging and may further promote the applications of responsive PCs, such as in displays and printing.

  4. The episodic engram transformed: Time reduces retrieval-related brain activity but correlates it with memory accuracy.

    PubMed

    Furman, Orit; Mendelsohn, Avi; Dudai, Yadin

    2012-11-15

    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 months. In contrast, BOLD activity in a retrieval-related set of brain areas during correctly remembered events was similar after hours and weeks but significantly declined after months. Despite this reduction, BOLD activity in retrieval-related regions was positively correlated with recognition accuracy only after months. Hippocampal engagement during retrieval remained similar over time during recall but decreased in recognition. Our results are in line with the hypothesis that hippocampus subserves retrieval of real-life episodic memory long after encoding, its engagement being dependent on retrieval demands. Furthermore, our findings suggest that over time episodic engrams are transformed into a parsimonious form capable of supporting accurate retrieval of the crux of events, arguably a critical goal of memory, with only minimal network activation.

  5. 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…

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

    PubMed

    Alkurt, Murat; Yeşıl Duymus, Zeynep; Dedeoglu, Numan

    2016-10-01

    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). 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). 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). The dimensional accuracy of impression material is clinically acceptable if the impression material is stored in suitable conditions.

  7. Assessing and Ensuring GOES-R Magnetometer Accuracy

    NASA Technical Reports Server (NTRS)

    Kronenwetter, Jeffrey; Carter, Delano R.; Todirita, Monica; Chu, Donald

    2016-01-01

    The GOES-R magnetometer accuracy requirement is 1.7 nanoteslas (nT). During quiet times (100 nT), accuracy is defined as absolute mean plus 3 sigma. During storms (300 nT), accuracy is defined as absolute mean plus 2 sigma. To achieve this, the sensor itself has better than 1 nT accuracy. Because zero offset and scale factor drift over time, it is also necessary to perform annual calibration maneuvers. To predict performance, we used covariance analysis and attempted to corroborate it with simulations. Although not perfect, the two generally agree and show the expected behaviors. With the annual calibration regimen, these predictions suggest that the magnetometers will meet their accuracy requirements.

  8. Reducing ambulance response times using discrete event simulation.

    PubMed

    Wei Lam, Sean Shao; Zhang, Zhong Cheng; Oh, Hong Choon; Ng, Yih Ying; Wah, Win; Hock Ong, Marcus Eng

    2014-01-01

    The objectives of this study are to develop a discrete-event simulation (DES) model for the Singapore Emergency Medical Services (EMS), and to demonstrate the utility of this DES model for the evaluation of different policy alternatives to improve ambulance response times. A DES model was developed based on retrospective emergency call data over a continuous 6-month period in Singapore. The main outcome measure is the distribution of response times. The secondary outcome measure is ambulance utilization levels based on unit hour utilization (UHU) ratios. The DES model was used to evaluate different policy options in order to improve the response times, while maintaining reasonable fleet utilization. Three policy alternatives looking at the reallocation of ambulances, the addition of new ambulances, and alternative dispatch policies were evaluated. Modifications of dispatch policy combined with the reallocation of existing ambulances were able to achieve response time performance equivalent to that of adding 10 ambulances. The median (90th percentile) response time was 7.08 minutes (12.69 minutes). Overall, this combined strategy managed to narrow the gap between the ideal and existing response time distribution by 11-13%. Furthermore, the median UHU under this combined strategy was 0.324 with an interquartile range (IQR) of 0.047 versus a median utilization of 0.285 (IQR of 0.051) resulting from the introduction of additional ambulances. Response times were shown to be improved via a more effective reallocation of ambulances and dispatch policy. More importantly, the response time improvements were achieved without a reduction in the utilization levels and additional costs associated with the addition of ambulances. We demonstrated the effective use of DES as a versatile platform to model the dynamic system complexities of Singapore's national EMS systems for the evaluation of operational strategies to improve ambulance response times.

  9. Evaluation of Application Accuracy and Performance of a Hydraulically Operated Variable-Rate Aerial Application System

    USDA-ARS?s Scientific Manuscript database

    An aerial variable-rate application system consisting of a DGPS-based guidance system, automatic flow controller, and hydraulically controlled pump/valve was evaluated for response time to rapidly changing flow requirements and accuracy of application. Spray deposition position error was evaluated ...

  10. Incorporating Response Times in Item Response Theory Models of Reading Comprehension Fluency

    ERIC Educational Resources Information Center

    Su, Shiyang

    2017-01-01

    With the online assessment becoming mainstream and the recording of response times becoming straightforward, the importance of response times as a measure of psychological constructs has been recognized and the literature of modeling times has been growing during the last few decades. Previous studies have tried to formulate models and theories to…

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

    PubMed

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

    2014-01-01

    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. 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. 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. 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.

  12. Pistol shooting accuracy as dependent on experience, eyes being opened and available viewing time.

    PubMed

    Goonetilleke, Ravindra S; Hoffmann, Errol R; Lau, Wing Chung

    2009-05-01

    A study of the shooting accuracy of three groups of pistol shooters is reported. The groups included (i) experienced gas pistol shooters; (ii) persons with experience in video shooting games; and (iii) persons with no shooting experience. The viewing time was varied in the tests. The results showed that experience had a significant effect on the mean and root mean square (RMS) shooting errors at the target. The results also showed that the viewing time does not need to exceed about 2s for an experienced pistol shooter and about 3s for a novice shooter to reach the best performance. Two models for the effects of limited viewing time are proposed; both models fit the data well when the viewing time is less than about 2s. The results indicated that the differences occurring with varying levels of experience are due to postural balance and not due to the aiming or cognitive component of the task.

  13. Communicating risk information: the influence of graphical display format on quantitative information perception-Accuracy, comprehension and preferences.

    PubMed

    Price, Melanie; Cameron, Rachel; Butow, Phyllis

    2007-12-01

    Statistical health risk information has proved notoriously confusing and difficult to understand. While past research indicates that presenting risk information in a frequency format is superior to relative risk and probability formats, the optimal characteristics of frequency formats are still unclear. The aim of this study is to determine the features of 1000 person frequency diagrams (pictographs) which result in the greatest speed and accuracy of graphical perception. Participants estimated the difference in chance of survival when taking or not taking Drug A, on a pictograph format, varying by mode (one-graph/two-graph), direction (vertical/horizontal), and shading (shaded/unshaded), and their preferences for the different formats. Their understanding of different components of the 1000 person diagram was assessed. Responses were timed and scored for accuracy. Horizontal pictographs were perceived faster and more accurately than vertical formats. Two-graph pictographs were perceived faster than one-graph formats. Shading reduced response time in two-graph formats, but increased response times in one-graph formats. Shaded and one-graph pictographs were preferred. As shading and one-graph formats were preferred, further clarification as to why shading negatively impacts on response times in the one-graph format is warranted. Horizontal pictographs are optimal.

  14. Fabrication of a Porous Fiber Cladding Material Using Microsphere Templating for Improved Response Time with Fiber Optic Sensor Arrays

    PubMed Central

    Henning, Paul E.; Rigo, M. Veronica; Geissinger, Peter

    2012-01-01

    A highly porous optical-fiber cladding was developed for evanescent-wave fiber sensors, which contains sensor molecules, maintains guiding conditions in the optical fiber, and is suitable for sensing in aqueous environments. To make the cladding material (a poly(ethylene) glycol diacrylate (PEGDA) polymer) highly porous, a microsphere templating strategy was employed. The resulting pore network increases transport of the target analyte to the sensor molecules located in the cladding, which improves the sensor response time. This was demonstrated using fluorescein-based pH sensor molecules, which were covalently attached to the cladding material. Scanning electron microscopy was used to examine the structure of the templated polymer and the large network of interconnected pores. Fluorescence measurements showed a tenfold improvement in the response time for the templated polymer and a reliable pH response over a pH range of five to nine with an estimated accuracy of 0.08 pH units. PMID:22654644

  15. Prediction of Time Response of Electrowetting

    NASA Astrophysics Data System (ADS)

    Lee, Seung Jun; Hong, Jiwoo; Kang, Kwan Hyoung

    2009-11-01

    It is very important to predict the time response of electrowetting-based devices, such as liquid lenses, reflective displays, and optical switches. We investigated the time response of electrowetting, based on an analytical and a numerical method, to find out characteristic scales and a scaling law for the switching time. For this, spreading process of a sessile droplet was analyzed based on the domain perturbation method. First, we considered the case of weakly viscous fluids. The analytical result for the spreading process was compared with experimental results, which showed very good agreement in overall time response. It was shown that the overall dynamics is governed by P2 shape mode. We derived characteristic scales combining the droplet volume, density, and surface tension. The overall dynamic process was scaled quite well by the scales. A scaling law was derived from the analytical solution and was verified experimentally. We also suggest a scaling law for highly viscous liquids, based on results of numerical analysis for the electrowetting-actuated spreading process.

  16. TimeXNet Web: Identifying cellular response networks from diverse omics time-course data.

    PubMed

    Tan, Phit Ling; López, Yosvany; Nakai, Kenta; Patil, Ashwini

    2018-05-14

    Condition-specific time-course omics profiles are frequently used to study cellular response to stimuli and identify associated signaling pathways. However, few online tools allow users to analyze multiple types of high-throughput time-course data. TimeXNet Web is a web server that extracts a time-dependent gene/protein response network from time-course transcriptomic, proteomic or phospho-proteomic data, and an input interaction network. It classifies the given genes/proteins into time-dependent groups based on the time of their highest activity and identifies the most probable paths connecting genes/proteins in consecutive groups. The response sub-network is enriched in activated genes/proteins and contains novel regulators that do not show any observable change in the input data. Users can view the resultant response network and analyze it for functional enrichment. TimeXNet Web supports the analysis of high-throughput data from multiple species by providing high quality, weighted protein-protein interaction networks for 12 model organisms. http://txnet.hgc.jp/. ashwini@hgc.jp. Supplementary data are available at Bioinformatics online.

  17. Executive Processes, Memory Accuracy, and Memory Monitoring: An Aging and Individual Difference Analysis

    ERIC Educational Resources Information Center

    Rhodes, M.G.; Kelley, C.M.

    2005-01-01

    The current study examined the neuropsychological correlates of memory accuracy in older and younger adults. Participants were tested in a memory monitoring paradigm developed by Koriat and Goldsmith (1996), which permits separate assessments of the accuracy of responses generated during retrieval and the accuracy of monitoring those responses.…

  18. 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

  19. Considering Time in Orthophotography Production: from a General Workflow to a Shortened Workflow for a Faster Disaster Response

    NASA Astrophysics Data System (ADS)

    Lucas, G.

    2015-08-01

    This article overall deals with production time with orthophoto imagery with medium size digital frame camera. The workflow examination follows two main parts: data acquisition and post-processing. The objectives of the research are fourfold: 1/ gathering time references for the most important steps of orthophoto production (it turned out that literature is missing on this topic); these figures are used later for total production time estimation; 2/ identifying levers for reducing orthophoto production time; 3/ building a simplified production workflow for emergency response: less exigent with accuracy and faster; and compare it to a classical workflow; 4/ providing methodical elements for the estimation of production time with a custom project. In the data acquisition part a comprehensive review lists and describes all the factors that may affect the acquisition efficiency. Using a simulation with different variables (average line length, time of the turns, flight speed) their effect on acquisition efficiency is quantitatively examined. Regarding post-processing, the time references figures were collected from the processing of a 1000 frames case study with 15 cm GSD covering a rectangular area of 447 km2; the time required to achieve each step during the production is written down. When several technical options are possible, each one is tested and time documented so as all alternatives are available. Based on a technical choice with the workflow and using the compiled time reference of the elementary steps, a total time is calculated for the post-processing of the 1000 frames. Two scenarios are compared as regards to time and accuracy. The first one follows the "normal" practices, comprising triangulation, orthorectification and advanced mosaicking methods (feature detection, seam line editing and seam applicator); the second is simplified and make compromise over positional accuracy (using direct geo-referencing) and seamlines preparation in order to achieve

  20. Assessing and Ensuring GOES-R Magnetometer Accuracy

    NASA Technical Reports Server (NTRS)

    Carter, Delano R.; Todirita, Monica; Kronenwetter, Jeffrey; Chu, Donald

    2016-01-01

    The GOES-R magnetometer subsystem accuracy requirement is 1.7 nanoteslas (nT). During quiet times (100 nT), accuracy is defined as absolute mean plus 3 sigma. During storms (300 nT), accuracy is defined as absolute mean plus 2 sigma. Error comes both from outside the magnetometers, e.g. spacecraft fields and misalignments, as well as inside, e.g. zero offset and scale factor errors. Because zero offset and scale factor drift over time, it will be necessary to perform annual calibration maneuvers. To predict performance before launch, we have used Monte Carlo simulations and covariance analysis. Both behave as expected, and their accuracy predictions agree within 30%. With the proposed calibration regimen, both suggest that the GOES-R magnetometer subsystem will meet its accuracy requirements.

  1. 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.

  2. 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.

  3. Response Time Differences between Computers and Tablets

    ERIC Educational Resources Information Center

    Kong, Xiaojing; Davis, Laurie Laughlin; McBride, Yuanyuan; Morrison, Kristin

    2018-01-01

    Item response time data were used in investigating the differences in student test-taking behavior between two device conditions: computer and tablet. Analyses were conducted to address the questions of whether or not the device condition had a differential impact on rapid guessing and solution behaviors (with response time effort used as an…

  4. 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. © The Author(s) 2015.

  5. Fixed-interval matching-to-sample: intermatching time and intermatching error runs1

    PubMed Central

    Nelson, Thomas D.

    1978-01-01

    Four pigeons were trained on a matching-to-sample task in which reinforcers followed either the first matching response (fixed interval) or the fifth matching response (tandem fixed-interval fixed-ratio) that occurred 80 seconds or longer after the last reinforcement. Relative frequency distributions of the matching-to-sample responses that concluded intermatching times and runs of mismatches (intermatching error runs) were computed for the final matching responses directly followed by grain access and also for the three matching responses immediately preceding the final match. Comparison of these two distributions showed that the fixed-interval schedule arranged for the preferential reinforcement of matches concluding relatively extended intermatching times and runs of mismatches. Differences in matching accuracy and rate during the fixed interval, compared to the tandem fixed-interval fixed-ratio, suggested that reinforcers following matches concluding various intermatching times and runs of mismatches influenced the rate and accuracy of the last few matches before grain access, but did not control rate and accuracy throughout the entire fixed-interval period. PMID:16812032

  6. 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

  7. Method to improve the blade tip-timing accuracy of fiber bundle sensor under varying tip clearance

    NASA Astrophysics Data System (ADS)

    Duan, Fajie; Zhang, Jilong; Jiang, Jiajia; Guo, Haotian; Ye, Dechao

    2016-01-01

    Blade vibration measurement based on the blade tip-timing method has become an industry-standard procedure. Fiber bundle sensors are widely used for tip-timing measurement. However, the variation of clearance between the sensor and the blade will bring a tip-timing error to fiber bundle sensors due to the change in signal amplitude. This article presents methods based on software and hardware to reduce the error caused by the tip clearance change. The software method utilizes both the rising and falling edges of the tip-timing signal to determine the blade arrival time, and a calibration process suitable for asymmetric tip-timing signals is presented. The hardware method uses an automatic gain control circuit to stabilize the signal amplitude. Experiments are conducted and the results prove that both methods can effectively reduce the impact of tip clearance variation on the blade tip-timing and improve the accuracy of measurements.

  8. 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…

  9. Accuracy and reproducibility of bending stiffness measurements by mechanical response tissue analysis in artificial human ulnas.

    PubMed

    Arnold, Patricia A; Ellerbrock, Emily R; Bowman, Lyn; Loucks, Anne B

    2014-11-07

    Osteoporosis is characterized by reduced bone strength, but no FDA-approved medical device measures bone strength. Bone strength is strongly associated with bone stiffness, but no FDA-approved medical device measures bone stiffness either. Mechanical Response Tissue Analysis (MRTA) is a non-significant risk, non-invasive, radiation-free, vibration analysis technique for making immediate, direct functional measurements of the bending stiffness of long bones in humans in vivo. MRTA has been used for research purposes for more than 20 years, but little has been published about its accuracy. To begin to investigate its accuracy, we compared MRTA measurements of bending stiffness in 39 artificial human ulna bones to measurements made by Quasistatic Mechanical Testing (QMT). In the process, we also quantified the reproducibility (i.e., precision and repeatability) of both methods. MRTA precision (1.0±1.0%) and repeatability (3.1 ± 3.1%) were not as high as those of QMT (0.2 ± 0.2% and 1.3+1.7%, respectively; both p<10(-4)). The relationship between MRTA and QMT measurements of ulna bending stiffness was indistinguishable from the identity line (p=0.44) and paired measurements by the two methods agreed within a 95% confidence interval of ± 5%. If such accuracy can be achieved on real human ulnas in situ, and if the ulna is representative of the appendicular skeleton, MRTA may prove clinically useful. Copyright © 2014 Elsevier Ltd. All rights reserved.

  10. Use of in Vitro HTS-Derived Concentration–Response Data as Biological Descriptors Improves the Accuracy of QSAR Models of in Vivo Toxicity

    PubMed Central

    Sedykh, Alexander; Zhu, Hao; Tang, Hao; Zhang, Liying; Richard, Ann; Rusyn, Ivan; Tropsha, Alexander

    2011-01-01

    Background Quantitative high-throughput screening (qHTS) assays are increasingly being used to inform chemical hazard identification. Hundreds of chemicals have been tested in dozens of cell lines across extensive concentration ranges by the National Toxicology Program in collaboration with the National Institutes of Health Chemical Genomics Center. Objectives Our goal was to test a hypothesis that dose–response data points of the qHTS assays can serve as biological descriptors of assayed chemicals and, when combined with conventional chemical descriptors, improve the accuracy of quantitative structure–activity relationship (QSAR) models applied to prediction of in vivo toxicity end points. Methods We obtained cell viability qHTS concentration–response data for 1,408 substances assayed in 13 cell lines from PubChem; for a subset of these compounds, rodent acute toxicity half-maximal lethal dose (LD50) data were also available. We used the k nearest neighbor classification and random forest QSAR methods to model LD50 data using chemical descriptors either alone (conventional models) or combined with biological descriptors derived from the concentration–response qHTS data (hybrid models). Critical to our approach was the use of a novel noise-filtering algorithm to treat qHTS data. Results Both the external classification accuracy and coverage (i.e., fraction of compounds in the external set that fall within the applicability domain) of the hybrid QSAR models were superior to conventional models. Conclusions Concentration–response qHTS data may serve as informative biological descriptors of molecules that, when combined with conventional chemical descriptors, may considerably improve the accuracy and utility of computational approaches for predicting in vivo animal toxicity end points. PMID:20980217

  11. Effects of training and simulated combat stress on leg tourniquet application accuracy, time, and effectiveness.

    PubMed

    Schreckengaust, Richard; Littlejohn, Lanny; Zarow, Gregory J

    2014-02-01

    The lower extremity tourniquet failure rate remains significantly higher in combat than in preclinical testing, so we hypothesized that tourniquet placement accuracy, speed, and effectiveness would improve during training and decline during simulated combat. Navy Hospital Corpsman (N = 89), enrolled in a Tactical Combat Casualty Care training course in preparation for deployment, applied Combat Application Tourniquet (CAT) and the Special Operations Forces Tactical Tourniquet (SOFT-T) on day 1 and day 4 of classroom training, then under simulated combat, wherein participants ran an obstacle course to apply a tourniquet while wearing full body armor and avoiding simulated small arms fire (paint balls). Application time and pulse elimination effectiveness improved day 1 to day 4 (p < 0.005). Under simulated combat, application time slowed significantly (p < 0.001), whereas accuracy and effectiveness declined slightly. Pulse elimination was poor for CAT (25% failure) and SOFT-T (60% failure) even in classroom conditions following training. CAT was more quickly applied (p < 0.005) and more effective (p < 0.002) than SOFT-T. Training fostered fast and effective application of leg tourniquets while performance declined under simulated combat. The inherent efficacy of tourniquet products contributes to high failure rates under combat conditions, pointing to the need for superior tourniquets and for rigorous deployment preparation training in simulated combat scenarios. Reprint & Copyright © 2014 Association of Military Surgeons of the U.S.

  12. The Screening Accuracy of the Parent and Teacher-Reported Social Responsiveness Scale (SRS): Comparison with the 3Di and ADOS

    ERIC Educational Resources Information Center

    Duvekot, Jorieke; van der Ende, Jan; Verhulst, Frank C.; Greaves-Lord, Kirstin

    2015-01-01

    The screening accuracy of the parent and teacher-reported Social Responsiveness Scale (SRS) was compared with an autism spectrum disorder (ASD) classification according to (1) the Developmental, Dimensional, and Diagnostic Interview (3Di), (2) the Autism Diagnostic Observation Schedule (ADOS), (3) both the 3Di and ADOS, in 186 children referred to…

  13. 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…

  14. Cost and accuracy of advanced breeding trial designs in apple

    PubMed Central

    Harshman, Julia M; Evans, Kate M; Hardner, Craig M

    2016-01-01

    Trialing advanced candidates in tree fruit crops is expensive due to the long-term nature of the planting and labor-intensive evaluations required to make selection decisions. How closely the trait evaluations approximate the true trait value needs balancing with the cost of the program. Designs of field trials of advanced apple candidates in which reduced number of locations, the number of years and the number of harvests per year were modeled to investigate the effect on the cost and accuracy in an operational breeding program. The aim was to find designs that would allow evaluation of the most additional candidates while sacrificing the least accuracy. Critical percentage difference, response to selection, and correlated response were used to examine changes in accuracy of trait evaluations. For the quality traits evaluated, accuracy and response to selection were not substantially reduced for most trial designs. Risk management influences the decision to change trial design, and some designs had greater risk associated with them. Balancing cost and accuracy with risk yields valuable insight into advanced breeding trial design. The methods outlined in this analysis would be well suited to other horticultural crop breeding programs. PMID:27019717

  15. Time needed to achieve completeness and accuracy in bedside lung ultrasound reporting in intensive care unit.

    PubMed

    Tutino, Lorenzo; Cianchi, Giovanni; Barbani, Francesco; Batacchi, Stefano; Cammelli, Rita; Peris, Adriano

    2010-08-12

    The use of lung ultrasound (LUS) in ICU is increasing but ultrasonographic patterns of lung are often difficult to quantify by different operators. The aim of this study was to evaluate the accuracy and quality of LUS reporting after the introduction of a standardized electronic recording sheet. Intensivists were trained for LUS following a teaching programme. From April 2008, an electronic sheet was designed and introduced in ICU database in order to uniform LUS examination reporting. A mark from 0 to 24 has been given for each exam by two senior intensivists not involved in the survey. The mark assigned was based on completeness of a precise reporting scheme, concerning the main finding of LUS. A cut off of 15 was considered sufficiency. The study comprehended 12 months of observations and a total of 637 LUS. Initially, although some improvement in the reports completeness, still the accuracy and precision of examination reporting was below 15. The time required to reach a sufficient quality was 7 months. A linear trend in physicians progress was observed. The uniformity in teaching programme and examinations reporting system permits to improve the level of completeness and accuracy of LUS reporting, helping physicians in following lung pathology evolution.

  16. ON-LINE MONITORING OF I&C TRANSMITTERS AND SENSORS FOR CALIBRATION VERIFICATION AND RESPONSE TIME TESTING WAS SUCCESSFULLY IMPLEMENTED AT ATR

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Erickson, Phillip A.; O'Hagan, Ryan; Shumaker, Brent

    The Advanced Test Reactor (ATR) has always had a comprehensive procedure to verify the performance of its critical transmitters and sensors, including RTDs, and pressure, level, and flow transmitters. These transmitters and sensors have been periodically tested for response time and calibration verification to ensure accuracy. With implementation of online monitoring techniques at ATR, the calibration verification and response time testing of these transmitters and sensors are verified remotely, automatically, hands off, include more portions of the system, and can be performed at almost any time during process operations. The work was done under a DOE funded SBIR project carriedmore » out by AMS. As a result, ATR is now able to save the manpower that has been spent over the years on manual calibration verification and response time testing of its temperature and pressure sensors and refocus those resources towards more equipment reliability needs. More importantly, implementation of OLM will help enhance the overall availability, safety, and efficiency. Together with equipment reliability programs of ATR, the integration of OLM will also help with I&C aging management goals of the Department of Energy and long-time operation of ATR.« less

  17. Impact of the diagnostic process on the accuracy of source identification and time to antibiotics in septic emergency department patients.

    PubMed

    Uittenbogaard, Annemieke J M; de Deckere, Ernie R J T; Sandel, Maro H; Vis, Alice; Houser, Christine M; de Groot, Bas

    2014-06-01

    Timely administration of effective antibiotics is important in sepsis management. Source-targeted antibiotics are believed to be most effective, but source identification could cause time delays. First, to describe the accuracy/time delays of a diagnostic work-up and the association with time to antibiotics in septic emergency department (ED) patients. Second, to assess the fraction in which source-targeted antibiotics could have been administered solely on the basis of patient history and physical examination. Secondary analysis of the prospective observational study on septic ED patients was carried out. The time to test result availability was associated with time to antibiotics. The accuracy of the suspected source of infection in the ED was assessed. For patients with pneumosepsis, urosepsis, and abdominal sepsis, combinations of signs and symptoms were assessed to achieve a maximal positive predictive value for the sepsis source, identifying a subset of patients in whom source-targeted antibiotics could be administered without waiting for diagnostic test results. The time to antibiotics increased by 18 (95% confidence interval: 12-24) min/h delay in test result availability (n=323). In 38-79% of patients, antibiotics were administered after additional tests, whereas the ED diagnosis was correct in 68-85% of patients. The maximal positive predictive value of signs and symptoms was 0.87 for patients with pneumosepsis and urosepsis and 0.75 for those with abdominal sepsis. Use of signs and symptoms would have led to correct ED diagnosis in 33% of patients. Diagnostic tests are associated with delayed administration of antibiotics to septic ED patients while increasing the diagnostic accuracy to only 68-85%. In one-third of septic ED patients, the choice of antibiotics could have been accurately determined solely on the basis of patient history and physical examination.

  18. The effects of aging on the speed-accuracy compromise: Boundary optimality in the diffusion model.

    PubMed

    Starns, Jeffrey J; Ratcliff, Roger

    2010-06-01

    We evaluated age-related differences in the optimality of decision boundary settings in a diffusion model analysis. In the model, the width of the decision boundary represents the amount of evidence that must accumulate in favor of a response alternative before a decision is made. Wide boundaries lead to slow but accurate responding, and narrow boundaries lead to fast but inaccurate responding. There is a single value of boundary separation that produces the most correct answers in a given period of time, and we refer to this value as the reward rate optimal boundary (RROB). We consistently found across a variety of decision tasks that older adults used boundaries that were much wider than the RROB value. Young adults used boundaries that were closer to the RROB value, although age differences in optimality were smaller with instructions emphasizing speed than with instructions emphasizing accuracy. Young adults adjusted their boundary settings to more closely approach the RROB value when they were provided with accuracy feedback and extensive practice. Older participants showed no evidence of making boundary adjustments in response to feedback or task practice, and they consistently used boundary separation values that produced accuracy levels that were near asymptote. Our results suggest that young adults attempt to balance speed and accuracy to achieve the most correct answers per unit time, whereas older adultts attempt to minimize errors even if they must respond quite slowly to do so. (c) 2010 APA, all rights reserved

  19. 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…

  20. The Dark Triad and the PID-5 Maladaptive Personality Traits: Accuracy, Confidence and Response Bias in Judgments of Veracity.

    PubMed

    Wissing, Benno G; Reinhard, Marc-André

    2017-01-01

    The Dark Triad traits-narcissism, Machiavellianism and psychopathy-have been found to be associated with intra- or interpersonal deception production frequency. This cross-sectional study ( N = 207) investigated if the Dark Triad traits are also associated with deception detection accuracy, as implicated by the recent conception of a deception-general ability. To investigate associations between maladaptive personality space and deception, the PID-5 maladaptive personality traits were included to investigate if besides Machiavellianism, Detachment is negatively associated with response bias. Finally, associations between the Dark Triad traits, Antagonism, Negative Affectivity and confidence judgments were investigated. Participants watched videos of lying vs. truth-telling senders and judged the truthfulness of the statements. None of the Dark Triad traits was found to be associated with the ability to detect deception. Detachment was negatively associated with response bias. Psychopathy was associated with global confidence judgments. The results provide additional support that dark and maladaptive personality traits are associated with judgmental biases but not with accuracy in deception detection. The internal consistencies of 4 of the 8 subscales of the used personality short scales were only low and nearly sufficient (αs =0.65-0.69).

  1. The relationship between digital model accuracy and time-dependent deformation of alginate impressions.

    PubMed

    Alcan, Toros; Ceylanoğlu, Cenk; Baysal, Bekir

    2009-01-01

    To investigate the effects of different storage periods of alginate impressions on digital model accuracy. A total of 105 impressions were taken from a master model with three different brands of alginates and were poured into stone models in five different storage periods. In all, 21 stone models were poured and immediately were scanned, and 21 digital models were prepared. The remaining 84 impressions were poured after 1, 2, 3, and 4 days, respectively. Five linear measurements were made by three researchers on the master model, the stone models, and the digital models. Time-dependent deformation of alginate impressions at different storage periods and the accuracy of traditional stone models and digital models were evaluated separately. Both the stone models and the digital models were highly correlated with the master model. Significant deformities in the alginate impressions were noted at different storage periods of 1 to 4 days. Alginate impressions of different brands also showed significant differences between each other on the first, third, and fourth days. Digital orthodontic models are as reliable as traditional stone models and probably will become the standard for orthodontic clinical use. Storing alginate impressions in sealed plastic bags for up to 4 days caused statistically significant deformation of alginate impressions, but the magnitude of these deformations did not appear to be clinically relevant and had no adverse effect on digital modeling.

  2. 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

  3. Experimental investigation of stress-inducing properties of system response times.

    PubMed

    Kuhmann, W

    1989-03-01

    System response times are regarded as a major stressor in human-computer interaction. In two earlier studies short (2s) and long (8s) response times were found to have differential effects on psychological, subjective, and performance variables, but results did not favour either response time. Therefore, in another laboratory study with 48 subjects in four independent groups working at a stimulated computer workplace, system response times of 2, 4, 6 and 8s were introduced in the same error detection task as used before, during 3 training and 5 working trials of 20 min each, and the same physiological, subjective and performance measures were obtained. There were no global effects on physiological variables, possibly due to low work load as a result of missing time pressure, but subjective and performance variables clearly favoured the longer system response times. When task periods and response time-periods were analysed separately, a shift of electrodermal activity could be observed from task- to response time-periods during the course of trials in the 8s condition. This did not appear in any other condition, which points to psychophysiological excitement that develops when system response times are too long, thus providing support for the concept of optimal system response times.

  4. A semi-parametric within-subject mixture approach to the analyses of responses and response times.

    PubMed

    Molenaar, Dylan; Bolsinova, Maria; Vermunt, Jeroen K

    2018-05-01

    In item response theory, modelling the item response times in addition to the item responses may improve the detection of possible between- and within-subject differences in the process that resulted in the responses. For instance, if respondents rely on rapid guessing on some items but not on all, the joint distribution of the responses and response times will be a multivariate within-subject mixture distribution. Suitable parametric methods to detect these within-subject differences have been proposed. In these approaches, a distribution needs to be assumed for the within-class response times. In this paper, it is demonstrated that these parametric within-subject approaches may produce false positives and biased parameter estimates if the assumption concerning the response time distribution is violated. A semi-parametric approach is proposed which resorts to categorized response times. This approach is shown to hardly produce false positives and parameter bias. In addition, the semi-parametric approach results in approximately the same power as the parametric approach. © 2017 The British Psychological Society.

  5. Revealing Real-Time Emotional Responses: a Personalized Assessment based on Heartbeat Dynamics

    NASA Astrophysics Data System (ADS)

    Valenza, Gaetano; Citi, Luca; Lanatá, Antonio; Scilingo, Enzo Pasquale; Barbieri, Riccardo

    2014-05-01

    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.

  6. Revealing real-time emotional responses: a personalized assessment based on heartbeat dynamics.

    PubMed

    Valenza, Gaetano; Citi, Luca; Lanatá, Antonio; Scilingo, Enzo Pasquale; Barbieri, Riccardo

    2014-05-21

    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.

  7. Accuracy of a real-time continuous glucose monitoring system in children with septic shock: A pilot study.

    PubMed

    Prabhudesai, Sumant; Kanjani, Amruta; Bhagat, Isha; Ravikumar, Karnam G; Ramachandran, Bala

    2015-11-01

    The aim of this prospective, observational study was to determine the accuracy of a real-time continuous glucose monitoring system (CGMS) in children with septic shock. Children aged 30 days to 18 years admitted to the Pediatric Intensive Care Unit with septic shock were included. A real-time CGMS sensor was used to obtain interstitial glucose readings. CGMS readings were compared statistically with simultaneous laboratory blood glucose (BG). Nineteen children were included, and 235 pairs of BG-CGMS readings were obtained. BG and CGMS had a correlation coefficient of 0.61 (P < 0.001) and a median relative absolute difference of 17.29%. On Clarke's error grid analysis, 222 (94.5%) readings were in the clinically acceptable zones (A and B). When BG was < 70, 70-180, and > 180 mg/dL, 44%, 100%, and 76.9% readings were in zones A and B, respectively (P < 0.001). The accuracy of CGMS was not affected by the presence of edema, acidosis, vasopressors, steroids, or renal replacement therapy. On receiver operating characteristics curve analysis, a CGMS reading <97 mg/dL predicted hypoglycemia (sensitivity 85.2%, specificity 75%, area under the curve [AUC] =0.85). A reading > 141 mg/dL predicted hyperglycemia (sensitivity 84.6%, specificity 89.6%, AUC = 0.87). CGMS provides a fairly, accurate estimate of BG in children with septic shock. It is unaffected by a variety of clinical variables. The accuracy over extremes of blood sugar may be a concern. We recommend larger studies to evaluate its use for the early detection of hypoglycemia and hyperglycemia.

  8. Analytic Guided-Search Model of Human Performance Accuracy in Target- Localization Search Tasks

    NASA Technical Reports Server (NTRS)

    Eckstein, Miguel P.; Beutter, Brent R.; Stone, Leland S.

    2000-01-01

    Current models of human visual search have extended the traditional serial/parallel search dichotomy. Two successful models for predicting human visual search are the Guided Search model and the Signal Detection Theory model. Although these models are inherently different, it has been difficult to compare them because the Guided Search model is designed to predict response time, while Signal Detection Theory models are designed to predict performance accuracy. Moreover, current implementations of the Guided Search model require the use of Monte-Carlo simulations, a method that makes fitting the model's performance quantitatively to human data more computationally time consuming. We have extended the Guided Search model to predict human accuracy in target-localization search tasks. We have also developed analytic expressions that simplify simulation of the model to the evaluation of a small set of equations using only three free parameters. This new implementation and extension of the Guided Search model will enable direct quantitative comparisons with human performance in target-localization search experiments and with the predictions of Signal Detection Theory and other search accuracy models.

  9. Towards improving diagnosis of memory loss in general practice: TIMeLi diagnostic test accuracy study protocol.

    PubMed

    Creavin, Sam T; Cullum, Sarah J; Haworth, Judy; Wye, Lesley; Bayer, Antony; Fish, Mark; Purdy, Sarah; Ben-Shlomo, Yoav

    2016-07-19

    People with cognitive problems, and their families, report distress and uncertainty whilst undergoing evaluation for dementia and perceive that traditional diagnostic evaluation in secondary care is insufficiently patient centred. The James Lind Alliance has prioritised research to investigate the role of primary care in supporting a more effective diagnostic pathway, and the topic is also of interest to health commissioners. However, there are very few studies that investigate the accuracy of diagnostic tests for dementia in primary care. We will conduct a prospective diagnostic test accuracy study to evaluate the accuracy of a range of simple tests for diagnosing all-cause-dementia in symptomatic people aged over 70 years who have consulted with their general practitioner (GP). We will invite eligible people to attend a research clinic where they will undergo a range of index tests that a GP could perform in the surgery and also be assessed by a specialist in memory disorders at the same appointment. Participating GPs will request neuroimaging and blood tests and otherwise manage patients in line with their usual clinical practice. The reference standard will be the consensus judgement of three experts (neurologist, psychiatrist and geriatrician) based on information from the specialist assessment, GP records and investigations, but not including items in the index test battery. The target condition will be all-cause dementia but we will also investigate diagnostic accuracy for sub-types where possible. We will use qualitative interviews with patients and focus groups with clinicians to help us understand the acceptability and feasibility of diagnosing dementia in primary care using the tests that we are investigating. Our results will help clinicians decide on which tests to perform in someone where there is concern about possible dementia and inform commissioning of diagnostic pathways.

  10. Number-Density Measurements of CO2 in Real Time with an Optical Frequency Comb for High Accuracy and Precision

    NASA Astrophysics Data System (ADS)

    Scholten, Sarah K.; Perrella, Christopher; Anstie, James D.; White, Richard T.; Al-Ashwal, Waddah; Hébert, Nicolas Bourbeau; Genest, Jérôme; Luiten, Andre N.

    2018-05-01

    Real-time and accurate measurements of gas properties are highly desirable for numerous real-world applications. Here, we use an optical-frequency comb to demonstrate absolute number-density and temperature measurements of a sample gas with state-of-the-art precision and accuracy. The technique is demonstrated by measuring the number density of 12C16O2 with an accuracy of better than 1% and a precision of 0.04% in a measurement and analysis cycle of less than 1 s. This technique is transferable to numerous molecular species, thus offering an avenue for near-universal gas concentration measurements.

  11. A laboratory assessment of the measurement accuracy of weighing type rainfall intensity gauges

    NASA Astrophysics Data System (ADS)

    Colli, M.; Chan, P. W.; Lanza, L. G.; La Barbera, P.

    2012-04-01

    In recent years the WMO Commission for Instruments and Methods of Observation (CIMO) fostered noticeable advancements in the accuracy of precipitation measurement issue by providing recommendations on the standardization of equipment and exposure, instrument calibration and data correction as a consequence of various comparative campaigns involving manufacturers and national meteorological services from the participating countries (Lanza et al., 2005; Vuerich et al., 2009). Extreme events analysis is proven to be highly affected by the on-site RI measurement accuracy (see e.g. Molini et al., 2004) and the time resolution of the available RI series certainly constitutes another key-factor in constructing hyetographs that are representative of real rain events. The OTT Pluvio2 weighing gauge (WG) and the GEONOR T-200 vibrating-wire precipitation gauge demonstrated very good performance under previous constant flow rate calibration efforts (Lanza et al., 2005). Although WGs do provide better performance than more traditional Tipping Bucket Rain gauges (TBR) under continuous and constant reference intensity, dynamic effects seem to affect the accuracy of WG measurements under real world/time varying rainfall conditions (Vuerich et al., 2009). The most relevant is due to the response time of the acquisition system and the derived systematic delay of the instrument in assessing the exact weight of the bin containing cumulated precipitation. This delay assumes a relevant role in case high resolution rain intensity time series are sought from the instrument, as is the case of many hydrologic and meteo-climatic applications. This work reports the laboratory evaluation of Pluvio2 and T-200 rainfall intensity measurements accuracy. Tests are carried out by simulating different artificial precipitation events, namely non-stationary rainfall intensity, using a highly accurate dynamic rainfall generator. Time series measured by an Ogawa drop counter (DC) at a field test site

  12. Between simplicity and accuracy: Effect of adding modeling details on quarter vehicle model accuracy.

    PubMed

    Soong, Ming Foong; Ramli, Rahizar; Saifizul, Ahmad

    2017-01-01

    Quarter vehicle model is the simplest representation of a vehicle that belongs to lumped-mass vehicle models. It is widely used in vehicle and suspension analyses, particularly those related to ride dynamics. However, as much as its common adoption, it is also commonly accepted without quantification that this model is not as accurate as many higher-degree-of-freedom models due to its simplicity and limited degrees of freedom. This study investigates the trade-off between simplicity and accuracy within the context of quarter vehicle model by determining the effect of adding various modeling details on model accuracy. In the study, road input detail, tire detail, suspension stiffness detail and suspension damping detail were factored in, and several enhanced models were compared to the base model to assess the significance of these details. The results clearly indicated that these details do have effect on simulated vehicle response, but to various extents. In particular, road input detail and suspension damping detail have the most significance and are worth being added to quarter vehicle model, as the inclusion of these details changed the response quite fundamentally. Overall, when it comes to lumped-mass vehicle modeling, it is reasonable to say that model accuracy depends not just on the number of degrees of freedom employed, but also on the contributions from various modeling details.

  13. Between simplicity and accuracy: Effect of adding modeling details on quarter vehicle model accuracy

    PubMed Central

    2017-01-01

    Quarter vehicle model is the simplest representation of a vehicle that belongs to lumped-mass vehicle models. It is widely used in vehicle and suspension analyses, particularly those related to ride dynamics. However, as much as its common adoption, it is also commonly accepted without quantification that this model is not as accurate as many higher-degree-of-freedom models due to its simplicity and limited degrees of freedom. This study investigates the trade-off between simplicity and accuracy within the context of quarter vehicle model by determining the effect of adding various modeling details on model accuracy. In the study, road input detail, tire detail, suspension stiffness detail and suspension damping detail were factored in, and several enhanced models were compared to the base model to assess the significance of these details. The results clearly indicated that these details do have effect on simulated vehicle response, but to various extents. In particular, road input detail and suspension damping detail have the most significance and are worth being added to quarter vehicle model, as the inclusion of these details changed the response quite fundamentally. Overall, when it comes to lumped-mass vehicle modeling, it is reasonable to say that model accuracy depends not just on the number of degrees of freedom employed, but also on the contributions from various modeling details. PMID:28617819

  14. Controlled Substance Reconciliation Accuracy Improvement Using Near Real-Time Drug Transaction Capture from Automated Dispensing Cabinets.

    PubMed

    Epstein, Richard H; Dexter, Franklin; Gratch, David M; Perino, Michael; Magrann, Jerry

    2016-06-01

    Accurate accounting of controlled drug transactions by inpatient hospital pharmacies is a requirement in the United States under the Controlled Substances Act. At many hospitals, manual distribution of controlled substances from pharmacies is being replaced by automated dispensing cabinets (ADCs) at the point of care. Despite the promise of improved accountability, a high prevalence (15%) of controlled substance discrepancies between ADC records and anesthesia information management systems (AIMS) has been published, with a similar incidence (15.8%; 95% confidence interval [CI], 15.3% to 16.2%) noted at our institution. Most reconciliation errors are clerical. In this study, we describe a method to capture drug transactions in near real-time from our ADCs, compare them with documentation in our AIMS, and evaluate subsequent improvement in reconciliation accuracy. ADC-controlled substance transactions are transmitted to a hospital interface server, parsed, reformatted, and sent to a software script written in Perl. The script extracts the data and writes them to a SQL Server database. Concurrently, controlled drug totals for each patient having care are documented in the AIMS and compared with the balance of the ADC transactions (i.e., vending, transferring, wasting, and returning drug). Every minute, a reconciliation report is available to anesthesia providers over the hospital Intranet from AIMS workstations. The report lists all patients, the current provider, the balance of ADC transactions, the totals from the AIMS, the difference, and whether the case is still ongoing or had concluded. Accuracy and latency of the ADC transaction capture process were assessed via simulation and by comparison with pharmacy database records, maintained by the vendor on a central server located remotely from the hospital network. For assessment of reconciliation accuracy over time, data were collected from our AIMS from January 2012 to June 2013 (Baseline), July 2013 to April 2014

  15. Cued Speech Transliteration: Effects of Speaking Rate and Lag Time on Production Accuracy

    ERIC Educational Resources Information Center

    Krause, Jean C.; Tessler, Morgan P.

    2016-01-01

    Many deaf and hard-of-hearing children rely on interpreters to access classroom communication. Although the exact level of access provided by interpreters in these settings is unknown, it is likely to depend heavily on interpreter accuracy (portion of message correctly produced by the interpreter) and the factors that govern interpreter accuracy.…

  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. Accuracy of Monte Carlo photon transport simulation in characterizing brachytherapy dosimeter energy-response artefacts.

    PubMed

    Das, R K; Li, Z; Perera, H; Williamson, J F

    1996-06-01

    Practical dosimeters in brachytherapy, such as thermoluminescent dosimeters (TLD) and diodes, are usually calibrated against low-energy megavoltage beams. To measure absolute dose rate near a brachytherapy source, it is necessary to establish the energy response of the detector relative to that of the calibration energy. The purpose of this paper is to assess the accuracy of Monte Carlo photon transport (MCPT) simulation in modelling the absolute detector response as a function of detector geometry and photon energy. We have exposed two different sizes of TLD-100 (LiF chips) and p-type silicon diode detectors to calibrated 60Co, HDR source (192Ir) and superficial x-ray beams. For the Scanditronix electron-field diode, the relative detector response, defined as the measured detector readings per measured unit of air kerma, varied from 38.46 V cGy-1 (40 kVp beam) to 6.22 V cGy-1 (60Co beam). Similarly for the large and small chips the same quantity varied from 2.08-3.02 nC cGy-1 and 0.171-0.244 nC cGy-1, respectively. Monte Carlo simulation was used to calculate the absorbed dose to the active volume of the detector per unit air kerma. If the Monte Carlo simulation is accurate, then the absolute detector response, which is defined as the measured detector reading per unit dose absorbed by the active detector volume, and is calculated by Monte Carlo simulation, should be a constant. For the diode, the absolute response is 5.86 +/- 0.15 (V cGy-1). For TLDs of size 3 x 3 x 1 mm3 the absolute response is 2.47 +/- 0.07 (nC cGy-1) and for TLDs of 1 x 1 x 1 mm3 it is 0.201 +/- 0.008 (nC cGy-1). From the above results we can conclude that the absolute response function of detectors (TLDs and diodes) is directly proportional to absorbed dose by the active volume of the detector and is independent of beam quality.

  18. Towards investigation of evolution of dynamical systems with independence of time accuracy: more classes of systems

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

    The recently developed method (Paper 1) enabling one to investigate the evolution of dynamical systems with an accuracy not dependent on time is developed further. The classes of dynamical systems which can be studied by that method are much extended, now including systems that are: (1) non-Hamiltonian, conservative; (2) Hamiltonian with time-dependent perturbation; (3) non-conservative (with dissipation). These systems cover various types of N-body gravitating systems of astrophysical and cosmological interest, such as the orbital evolution of planets, minor planets, artificial satellites due to tidal, non-tidal perturbations and thermal thrust, evolving close binary stellar systems, and the dynamics of accretion disks.

  19. Real-Time Continuous Response Spectra Exceedance Calculation

    NASA Astrophysics Data System (ADS)

    Vernon, Frank; Harvey, Danny; Lindquist, Kent; Franke, Mathias

    2017-04-01

    A novel approach is presented for near real-time earthquake alarms for critical structures at distributed locations using real-time estimation of response spectra obtained from near free-field motions. Influential studies dating back to the 1980s identified spectral response acceleration as a key ground motion characteristic that correlates well with observed damage in structures. Thus, monitoring and reporting on exceedance of spectra-based thresholds are useful tools for assessing the potential for damage to facilities or multi-structure campuses based on input ground motions only. With as little as one strong-motion station per site, this scalable approach can provide rapid alarms on the damage status of remote towns, critical infrastructure (e.g., hospitals, schools) and points of interests (e.g., bridges) for a very large number of locations enabling better rapid decision making during critical and difficult immediate post-earthquake response actions. Real-time calculation of PSA exceedance and alarm dissemination are enabled with Bighorn, a module included in the Antelope software package that combines real-time spectral monitoring and alarm capabilities with a robust built-in web display server. Examples of response spectra from several M 5 events recorded by the ANZA seismic network in southern California will be presented.

  20. A heteroscedastic generalized linear model with a non-normal speed factor for responses and response times.

    PubMed

    Molenaar, Dylan; Bolsinova, Maria

    2017-05-01

    In generalized linear modelling of responses and response times, the observed response time variables are commonly transformed to make their distribution approximately normal. A normal distribution for the transformed response times is desirable as it justifies the linearity and homoscedasticity assumptions in the underlying linear model. Past research has, however, shown that the transformed response times are not always normal. Models have been developed to accommodate this violation. In the present study, we propose a modelling approach for responses and response times to test and model non-normality in the transformed response times. Most importantly, we distinguish between non-normality due to heteroscedastic residual variances, and non-normality due to a skewed speed factor. In a simulation study, we establish parameter recovery and the power to separate both effects. In addition, we apply the model to a real data set. © 2017 The Authors. British Journal of Mathematical and Statistical Psychology published by John Wiley & Sons Ltd on behalf of British Psychological Society.

  1. Concurrent schedules: Effects of time- and response-allocation constraints

    PubMed Central

    Davison, Michael

    1991-01-01

    Five pigeons were trained on concurrent variable-interval schedules arranged on two keys. In Part 1 of the experiment, the subjects responded under no constraints, and the ratios of reinforcers obtainable were varied over five levels. In Part 2, the conditions of the experiment were changed such that the time spent responding on the left key before a subsequent changeover to the right key determined the minimum time that must be spent responding on the right key before a changeover to the left key could occur. When the left key provided a higher reinforcer rate than the right key, this procedure ensured that the time allocated to the two keys was approximately equal. The data showed that such a time-allocation constraint only marginally constrained response allocation. In Part 3, the numbers of responses emitted on the left key before a changeover to the right key determined the minimum number of responses that had to be emitted on the right key before a changeover to the left key could occur. This response constraint completely constrained time allocation. These data are consistent with the view that response allocation is a fundamental process (and time allocation a derivative process), or that response and time allocation are independently controlled, in concurrent-schedule performance. PMID:16812632

  2. Effect of Variations in IRU Integration Time Interval On Accuracy of Aqua Attitude Estimation

    NASA Technical Reports Server (NTRS)

    Natanson, G. A.; Tracewell, Dave

    2003-01-01

    During Aqua launch support, attitude analysts noticed several anomalies in Onboard Computer (OBC) rates and in rates computed by the ground Attitude Determination System (ADS). These included: 1) periodic jumps in the OBC pitch rate every 2 minutes; 2) spikes in ADS pitch rate every 4 minutes; 3) close agreement between pitch rates computed by ADS and those derived from telemetered OBC quaternions (in contrast to the step-wise pattern observed for telemetered OBC rates); 4) spikes of +/- 10 milliseconds in telemetered IRU integration time every 4 minutes (despite the fact that telemetered time tags of any two sequential IRU measurements were always 1 second apart from each other). An analysis presented in the paper explains this anomalous behavior by a small average offset of about 0.5 +/- 0.05 microsec in the time interval between two sequential accumulated angle measurements. It is shown that errors in the estimated pitch angle due to neglecting the aforementioned variations in the integration time interval by the OBC is within +/- 2 arcseconds. Ground attitude solutions are found to be accurate enough to see the effect of the variations on the accuracy of the estimated pitch angle.

  3. 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.

  4. The Screening Accuracy of the Parent and Teacher-Reported Social Responsiveness Scale (SRS): Comparison with the 3Di and ADOS.

    PubMed

    Duvekot, Jorieke; van der Ende, Jan; Verhulst, Frank C; Greaves-Lord, Kirstin

    2015-06-01

    The screening accuracy of the parent and teacher-reported Social Responsiveness Scale (SRS) was compared with an autism spectrum disorder (ASD) classification according to (1) the Developmental, Dimensional, and Diagnostic Interview (3 Di), (2) the Autism Diagnostic Observation Schedule (ADOS), (3) both the 3 Di and ADOS, in 186 children referred to six mental health centers. The parent report showed excellent correspondence to an ASD classification according to the 3 Di and both the 3 Di and ADOS. The teacher report added significantly to the screening accuracy over and above the parent report when compared with the ADOS classification. Findings support the screening utility of the parent-reported SRS among clinically referred children and indicate that different informants may provide unique information relevant for ASD assessment.

  5. Impact of Time to Maternal Interview on Interview Responses in the National Birth Defects Prevention Study

    PubMed Central

    Tinker, Sarah C.; Gibbs, Cassandra; Strickland, Matthew J.; Devine, Owen J.; Crider, Krista S.; Werler, Martha M.; Anderka, Marlene T.; Reefhuis, Jennita

    2013-01-01

    Prenatal exposures often are assessed using retrospective interviews. Time from exposure to interview may influence data accuracy. We investigated the association of time to interview (TTI) with aspects of interview responses in the National Birth Defects Prevention Study, a population-based case-control study of birth defects in 10 US states. Mothers completed a computer-assisted telephone interview 1.5–24 months after their estimated date of delivery. Proxy metrics for interview quality were whether certain exposures were reported, whether the start month of reported medication use or illness was reported, or whether responses were missing. Interaction by case status was assessed. Interviews were completed with 30,542 mothers (22,366 cases and 8,176 controls) who gave birth between 1997 and 2007. Mothers of cases were interviewed later than were mothers of controls (11.7 months vs. 9.5 months, respectively). In adjusted analyses, having a TTI that was greater than 6 months was associated with only a few aspects of interview responses (e.g., start month of pseudoephedrine use). Interaction by case-control status was observed for some exposures; mothers of controls had a greater reduction in interview quality with increased TTI in these instances (e.g., report of morning sickness, start month of acetaminophen use and ibuprofen use). The results suggest that TTI might impact interview responses; however, the impact may be minimal and specific to the type of exposure. PMID:23645625

  6. Impact of time to maternal interview on interview responses in the National Birth Defects Prevention Study.

    PubMed

    Tinker, Sarah C; Gibbs, Cassandra; Strickland, Matthew J; Devine, Owen J; Crider, Krista S; Werler, Martha M; Anderka, Marlene T; Reefhuis, Jennita

    2013-06-01

    Prenatal exposures often are assessed using retrospective interviews. Time from exposure to interview may influence data accuracy. We investigated the association of time to interview (TTI) with aspects of interview responses in the National Birth Defects Prevention Study, a population-based case-control study of birth defects in 10 US states. Mothers completed a computer-assisted telephone interview 1.5-24 months after their estimated date of delivery. Proxy metrics for interview quality were whether certain exposures were reported, whether the start month of reported medication use or illness was reported, or whether responses were missing. Interaction by case status was assessed. Interviews were completed with 30,542 mothers (22,366 cases and 8,176 controls) who gave birth between 1997 and 2007. Mothers of cases were interviewed later than were mothers of controls (11.7 months vs. 9.5 months, respectively). In adjusted analyses, having a TTI that was greater than 6 months was associated with only a few aspects of interview responses (e.g., start month of pseudoephedrine use). Interaction by case-control status was observed for some exposures; mothers of controls had a greater reduction in interview quality with increased TTI in these instances (e.g., report of morning sickness, start month of acetaminophen use and ibuprofen use). The results suggest that TTI might impact interview responses; however, the impact may be minimal and specific to the type of exposure.

  7. Acute effect of stretching modalities and time-pressure on accuracy and consistency of throwing darts among 12- and 13-year-old schoolboys.

    PubMed

    Frikha, Mohamed; Chaâri, Nesrine; Derbel, Mohammad S; Elghoul, Yousri; Zinkovsky, Anatoly V; Chamari, Karim

    2017-09-01

    The present study addressed the lack of data on the effect of different types of stretching on selected measures of throwing accuracy. We hypothesized that the stretching procedures, within pre-exercise warm-up, could affect the accuracy and the consistency in throwing darts performances under different stress conditions. Eighteen right-handed schoolboys (13.1±0.4 years, 166±0.1 cm and 54.5±9 kg; mean±SD) completed the Darts Throwing Accuracy Test in free (FDT) and in time-pressure (TPDT) conditions, either after static (SS), dynamic (DS), ballistic (BS) or no-stretching (NS) protocols, on nonconsecutive days and in a counter-balanced randomized order. After performing 5 minutes of light standardized jogging and one of the three stretching protocols for 10 minutes, each participant completed the FDT and TPDT tests. Mean scores, missed darts and variability of scores, were recorded and analyzed using a two-way ANOVA with repeated measures. Heart rate (HR), ratings of perceived exertion (RPE) and the task difficulty perception (DP), were recorded through each experimental session. There was no effect of the stretching procedures on accuracy in FDT. However, in the TPDT condition, better performances were recorded after NS and SS compared to DS and BS. The accuracy performances decreased in TPDT by 9.6% after NS (P<0.01); 15.3% after DS (P<0.001) and 11.8% after BS (P<0.001); but not after SS (P<0.05). Static stretching helped reducing the adverse effects of time-pressure on darts throwing performance. Consequently, static exercises are recommended before practicing activities requiring both upper limbs speed and accuracy.

  8. Oxytocin Reduces Face Processing Time but Leaves Recognition Accuracy and Eye-Gaze Unaffected.

    PubMed

    Hubble, Kelly; Daughters, Katie; Manstead, Antony S R; Rees, Aled; Thapar, Anita; van Goozen, Stephanie H M

    2017-01-01

    Previous studies have found that oxytocin (OXT) can improve the recognition of emotional facial expressions; it has been proposed that this effect is mediated by an increase in attention to the eye-region of faces. Nevertheless, evidence in support of this claim is inconsistent, and few studies have directly tested the effect of oxytocin on emotion recognition via altered eye-gaze Methods: In a double-blind, within-subjects, randomized control experiment, 40 healthy male participants received 24 IU intranasal OXT and placebo in two identical experimental sessions separated by a 2-week interval. Visual attention to the eye-region was assessed on both occasions while participants completed a static facial emotion recognition task using medium intensity facial expressions. Although OXT had no effect on emotion recognition accuracy, recognition performance was improved because face processing was faster across emotions under the influence of OXT. This effect was marginally significant (p<.06). Consistent with a previous study using dynamic stimuli, OXT had no effect on eye-gaze patterns when viewing static emotional faces and this was not related to recognition accuracy or face processing time. These findings suggest that OXT-induced enhanced facial emotion recognition is not necessarily mediated by an increase in attention to the eye-region of faces, as previously assumed. We discuss several methodological issues which may explain discrepant findings and suggest the effect of OXT on visual attention may differ depending on task requirements. (JINS, 2017, 23, 23-33).

  9. 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.

  10. Accuracy of responses from postal surveys about continuing medical education and information behavior: experiences from a survey among German diabetologists

    PubMed Central

    Trelle, Sven

    2002-01-01

    Background Postal surveys are a popular instrument for studies about continuing medical education habits. But little is known about the accuracy of responses in such surveys. The objective of this study was to quantify the magnitude of inaccurate responses in a postal survey among physicians. Methods A sub-analysis of a questionnaire about continuing medical education habits and information management was performed. The five variables used for the quantitative analysis are based on a question about the knowledge of a fictitious technical term and on inconsistencies in contingency tables of answers to logically connected questions. Results Response rate was 52%. Non-response bias is possible but seems not very likely since an association between demographic variables and inconsistent responses could not be found. About 10% of responses were inaccurate according to the definition. Conclusion It was shown that a sub-analysis of a questionnaire makes a quantification of inaccurate responses in postal surveys possible. This sub-analysis revealed that a notable portion of responses in a postal survey about continuing medical education habits and information management was inaccurate. PMID:12153701

  11. 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…

  12. Investigations on response time of magnetorheological elastomer under compression mode

    NASA Astrophysics Data System (ADS)

    Zhu, Mi; Yu, Miao; Qi, Song; Fu, Jie

    2018-05-01

    For efficient fast control of vibration system with magnetorheological elastomer (MRE)-based smart device, the response time of MRE material is the key parameter which directly affects the control performance of the vibration system. For a step coil current excitation, this paper proposed a Maxwell behavior model with time constant λ to describe the normal force response of MRE, and the response time of MRE was extracted through the separation of coil response time. Besides, the transient responses of MRE under compression mode were experimentally investigated, and the effects of (i) applied current, (ii) particle distribution and (iii) compressive strain on the response time of MRE were addressed. The results revealed that the three factors can affect the response characteristic of MRE quite significantly. Besides the intrinsic importance for contributing to the response evaluation and effective design of MRE device, this study may conduce to the optimal design of controller for MRE control system.

  13. Accuracy of Single Frequency GPS Observations Processing In Near Real-time With Use of Code Predicted Products

    NASA Astrophysics Data System (ADS)

    Wielgosz, P. A.

    In this year, the system of active geodetic GPS permanent stations is going to be estab- lished in Poland. This system should provide GPS observations for a wide spectrum of users, especially it will be a great opportunity for surveyors. Many of surveyors still use cheaper, single frequency receivers. This paper focuses on processing of single frequency GPS observations only. During processing of such observations the iono- sphere plays an important role, so we concentrated on the influence of the ionosphere on the positional coordinates. Twenty consecutive days of GPS data from 2001 year were processed to analyze the accuracy of a derived three-dimensional relative vec- tor position between GPS stations. Observations from two Polish EPN/IGS stations: BOGO and JOZE were used. In addition to, a new test station - IGIK was created. In this paper, the results of single frequency GPS observations processing in near real- time are presented. Baselines of 15, 27 and 42 kilometers and sessions of 1, 2, 3, 4, and 6 hours long were processed. While processing we used CODE (Centre for Orbit De- termination in Europe, Bern, Switzerland) predicted products: orbits and ionosphere info. These products are available in real-time and enable near real-time processing. Software Bernese v. 4.2 for Linux and BPE (Bernese Processing Engine) mode were used. These results are shown with a reference to dual frequency weekly solution (the best solution). Obtained GPS positional time and GPS baseline length dependency accuracy is presented for single frequency GPS observations.

  14. Quantifying and comparing dynamic predictive accuracy of joint models for longitudinal marker and time-to-event in presence of censoring and competing risks.

    PubMed

    Blanche, Paul; Proust-Lima, Cécile; Loubère, Lucie; Berr, Claudine; Dartigues, Jean-François; Jacqmin-Gadda, Hélène

    2015-03-01

    Thanks to the growing interest in personalized medicine, joint modeling of longitudinal marker and time-to-event data has recently started to be used to derive dynamic individual risk predictions. Individual predictions are called dynamic because they are updated when information on the subject's health profile grows with time. We focus in this work on statistical methods for quantifying and comparing dynamic predictive accuracy of this kind of prognostic models, accounting for right censoring and possibly competing events. Dynamic area under the ROC curve (AUC) and Brier Score (BS) are used to quantify predictive accuracy. Nonparametric inverse probability of censoring weighting is used to estimate dynamic curves of AUC and BS as functions of the time at which predictions are made. Asymptotic results are established and both pointwise confidence intervals and simultaneous confidence bands are derived. Tests are also proposed to compare the dynamic prediction accuracy curves of two prognostic models. The finite sample behavior of the inference procedures is assessed via simulations. We apply the proposed methodology to compare various prediction models using repeated measures of two psychometric tests to predict dementia in the elderly, accounting for the competing risk of death. Models are estimated on the French Paquid cohort and predictive accuracies are evaluated and compared on the French Three-City cohort. © 2014, The International Biometric Society.

  15. Two high accuracy digital integrators for Rogowski current transducers.

    PubMed

    Luo, Pan-dian; Li, Hong-bin; Li, Zhen-hua

    2014-01-01

    The Rogowski current transducers have been widely used in AC current measurement, but their accuracy is mainly subject to the analog integrators, which have typical problems such as poor long-term stability and being susceptible to environmental conditions. The digital integrators can be another choice, but they cannot obtain a stable and accurate output for the reason that the DC component in original signal can be accumulated, which will lead to output DC drift. Unknown initial conditions can also result in integral output DC offset. This paper proposes two improved digital integrators used in Rogowski current transducers instead of traditional analog integrators for high measuring accuracy. A proportional-integral-derivative (PID) feedback controller and an attenuation coefficient have been applied in improving the Al-Alaoui integrator to change its DC response and get an ideal frequency response. For the special design in the field of digital signal processing, the improved digital integrators have better performance than analog integrators. Simulation models are built for the purpose of verification and comparison. The experiments prove that the designed integrators can achieve higher accuracy than analog integrators in steady-state response, transient-state response, and temperature changing condition.

  16. Two high accuracy digital integrators for Rogowski current transducers

    NASA Astrophysics Data System (ADS)

    Luo, Pan-dian; Li, Hong-bin; Li, Zhen-hua

    2014-01-01

    The Rogowski current transducers have been widely used in AC current measurement, but their accuracy is mainly subject to the analog integrators, which have typical problems such as poor long-term stability and being susceptible to environmental conditions. The digital integrators can be another choice, but they cannot obtain a stable and accurate output for the reason that the DC component in original signal can be accumulated, which will lead to output DC drift. Unknown initial conditions can also result in integral output DC offset. This paper proposes two improved digital integrators used in Rogowski current transducers instead of traditional analog integrators for high measuring accuracy. A proportional-integral-derivative (PID) feedback controller and an attenuation coefficient have been applied in improving the Al-Alaoui integrator to change its DC response and get an ideal frequency response. For the special design in the field of digital signal processing, the improved digital integrators have better performance than analog integrators. Simulation models are built for the purpose of verification and comparison. The experiments prove that the designed integrators can achieve higher accuracy than analog integrators in steady-state response, transient-state response, and temperature changing condition.

  17. 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

  18. In-situ response time testing of thermocouples

    NASA Astrophysics Data System (ADS)

    Hashemian, H. M.; Petersen, K. M.; Hashemian, M.; Beverly, D. D.; Miller, L. F.

    The Loop Current Step Response (LCSR) method has been developed for in situ response time testing of thermocouples and resistance thermometers. A means for measuring the sensor response for actual operating conditions and installation details is provided. This technology is ready to be assembled into an instrument for use in aerospace, nuclear, chemical and other industries where transient temperature measurements are important. The method provides time constant results within better than about 20 percent of value obtained from plunge tests. These results are based on tests performed in water at low flow rates (1M/sec) and in air flow rates ranging from a few meters per second to over a hundred kilometers per hour.

  19. 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…

  20. 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. Copyright © 2015 Elsevier Inc. All rights reserved.

  1. 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.

  2. Response preparation and intra-individual reaction time variability in schizophrenia.

    PubMed

    Dankinas, Denisas; Mėlynytė, Sigita; Šiurkutė, Aldona; Dapšys, Kastytis

    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

  3. K+-selective nanospheres: maximising response range and minimising response time.

    PubMed

    Ruedas-Rama, Maria Jose; Hall, Elizabeth A H

    2006-12-01

    Cross-linked K(+) ion-selective copolymer nanospheres have been prepared by free-radical photo-initiated polymerization of n-butyl acrylate (nBA) with hexanedioldiacrylate (HDDA). Nanospheres (<200 nm) containing H(+)-chromoionophore (ETH 5294) and lipophilic salt (KTClPB) for H(+)-sensors, or ETH 5294, a K(+)-selective ionophore (valinomycin) and anionic sites for K(+)-sensors were compared, and the effect of varying the normalised concentrations for beta (R(T)(-)/L(T)) and gamma (C(m)(T)/L(T)) was studied. Experimental data were fitted to theoretical curves for the dynamic response range, based on the effect of changes in the concentration of these lipophilic sensing components incorporated into the spheres, and conditions identified for maximising the response range. A complex valinomycin-K(+) formation constant, log K(IL) = 13.13 +/- 2.22, was obtained in the nBA matrix, and from the calibration curves the apparent acid-dissociation equilibrium constant (pK(a) = 12.92 +/- 0.03) was extracted for the H(+)-sensing system, and the equilibrium exchange constant (pK(exch) = 6.16 +/- 0.03, at pH 7) calculated for the K(+)-sensing nanospheres. A basis for establishing optimum performance was identified, whereby response range and response time were balanced with maximum fluorescence yield. Parameters for achieving nanospheres with a response time <5 minutes, covering 2-3 orders of magnitude change in activity were identified, demanding nanospheres with radius <300 nm and beta(crit) approximately 0.6. An RSD(%) approximately 3% was obtained in a study of the reproducibility of the response of the proposed nanospheres, and selectivity was also evaluated for a K(+)-selective nanosensor using several cations as interfering agents. In most cases, the fluorescent emission spectra showed no response to the cations tested, confirming the selectivity of nanospheres to potassium ion. The nanosensors were satisfactorily applied to the determination of K(+) in samples mimicking

  4. fMRI evidence for a dual process account of the speed-accuracy tradeoff in decision-making.

    PubMed

    Ivanoff, Jason; Branning, Philip; Marois, René

    2008-07-09

    The speed and accuracy of decision-making have a well-known trading relationship: hasty decisions are more prone to errors while careful, accurate judgments take more time. Despite the pervasiveness of this speed-accuracy trade-off (SAT) in decision-making, its neural basis is still unknown. Using functional magnetic resonance imaging (fMRI) we show that emphasizing the speed of a perceptual decision at the expense of its accuracy lowers the amount of evidence-related activity in lateral prefrontal cortex. Moreover, this speed-accuracy difference in lateral prefrontal cortex activity correlates with the speed-accuracy difference in the decision criterion metric of signal detection theory. We also show that the same instructions increase baseline activity in a dorso-medial cortical area involved in the internal generation of actions. These findings suggest that the SAT is neurally implemented by modulating not only the amount of externally-derived sensory evidence used to make a decision, but also the internal urge to make a response. We propose that these processes combine to control the temporal dynamics of the speed-accuracy trade-off in decision-making.

  5. A simple two-stage model predicts response time distributions.

    PubMed

    Carpenter, R H S; Reddi, B A J; Anderson, A J

    2009-08-15

    The neural mechanisms underlying reaction times have previously been modelled in two distinct ways. When stimuli are hard to detect, response time tends to follow a random-walk model that integrates noisy sensory signals. But studies investigating the influence of higher-level factors such as prior probability and response urgency typically use highly detectable targets, and response times then usually correspond to a linear rise-to-threshold mechanism. Here we show that a model incorporating both types of element in series - a detector integrating noisy afferent signals, followed by a linear rise-to-threshold performing decision - successfully predicts not only mean response times but, much more stringently, the observed distribution of these times and the rate of decision errors over a wide range of stimulus detectability. By reconciling what previously may have seemed to be conflicting theories, we are now closer to having a complete description of reaction time and the decision processes that underlie it.

  6. Fast Numerical Solution of the Plasma Response Matrix for Real-time Ideal MHD Control

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Glasser, Alexander; Kolemen, Egemen; Glasser, Alan H.

    To help effectuate near real-time feedback control of ideal MHD instabilities in tokamak geometries, a parallelized version of A.H. Glasser’s DCON (Direct Criterion of Newcomb) code is developed. To motivate the numerical implementation, we first solve DCON’s δW formulation with a Hamilton-Jacobi theory, elucidating analytical and numerical features of the ideal MHD stability problem. The plasma response matrix is demonstrated to be the solution of an ideal MHD Riccati equation. We then describe our adaptation of DCON with numerical methods natural to solutions of the Riccati equation, parallelizing it to enable its operation in near real-time. We replace DCON’s serial integration of perturbed modes—which satisfy a singular Euler- Lagrange equation—with a domain-decomposed integration of state transition matrices. Output is shown to match results from DCON with high accuracy, and with computation time < 1s. Such computational speed may enable active feedback ideal MHD stability control, especially in plasmas whose ideal MHD equilibria evolve with inductive timescalemore » $$\\tau$$ ≳ 1s—as in ITER. Further potential applications of this theory are discussed.« less

  7. Fast Numerical Solution of the Plasma Response Matrix for Real-time Ideal MHD Control

    DOE PAGES

    Glasser, Alexander; Kolemen, Egemen; Glasser, Alan H.

    2018-03-26

    To help effectuate near real-time feedback control of ideal MHD instabilities in tokamak geometries, a parallelized version of A.H. Glasser’s DCON (Direct Criterion of Newcomb) code is developed. To motivate the numerical implementation, we first solve DCON’s δW formulation with a Hamilton-Jacobi theory, elucidating analytical and numerical features of the ideal MHD stability problem. The plasma response matrix is demonstrated to be the solution of an ideal MHD Riccati equation. We then describe our adaptation of DCON with numerical methods natural to solutions of the Riccati equation, parallelizing it to enable its operation in near real-time. We replace DCON’s serial integration of perturbed modes—which satisfy a singular Euler- Lagrange equation—with a domain-decomposed integration of state transition matrices. Output is shown to match results from DCON with high accuracy, and with computation time < 1s. Such computational speed may enable active feedback ideal MHD stability control, especially in plasmas whose ideal MHD equilibria evolve with inductive timescalemore » $$\\tau$$ ≳ 1s—as in ITER. Further potential applications of this theory are discussed.« less

  8. Developing a Weighted Measure of Speech Sound Accuracy

    PubMed Central

    Preston, Jonathan L.; Ramsdell, Heather L.; Oller, D. Kimbrough; Edwards, Mary Louise; Tobin, Stephen J.

    2010-01-01

    Purpose The purpose is to develop a system for numerically quantifying a speaker’s phonetic accuracy through transcription-based measures. With a focus on normal and disordered speech in children, we describe a system for differentially weighting speech sound errors based on various levels of phonetic accuracy with a Weighted Speech Sound Accuracy (WSSA) score. We then evaluate the reliability and validity of this measure. Method Phonetic transcriptions are analyzed from several samples of child speech, including preschoolers and young adolescents with and without speech sound disorders and typically developing toddlers. The new measure of phonetic accuracy is compared to existing measures, is used to discriminate typical and disordered speech production, and is evaluated to determine whether it is sensitive to changes in phonetic accuracy over time. Results Initial psychometric data indicate that WSSA scores correlate with other measures of phonetic accuracy as well as listeners’ judgments of severity of a child’s speech disorder. The measure separates children with and without speech sound disorders. WSSA scores also capture growth in phonetic accuracy in toddler’s speech over time. Conclusion Results provide preliminary support for the WSSA as a valid and reliable measure of phonetic accuracy in children’s speech. PMID:20699344

  9. Using Response Times for Item Selection in Adaptive Testing

    ERIC Educational Resources Information Center

    van der Linden, Wim J.

    2008-01-01

    Response times on items can be used to improve item selection in adaptive testing provided that a probabilistic model for their distribution is available. In this research, the author used a hierarchical modeling framework with separate first-level models for the responses and response times and a second-level model for the distribution of the…

  10. Outcome Prediction in Mathematical Models of Immune Response to Infection.

    PubMed

    Mai, Manuel; Wang, Kun; Huber, Greg; Kirby, Michael; Shattuck, Mark D; O'Hern, Corey S

    2015-01-01

    Clinicians need to predict patient outcomes with high accuracy as early as possible after disease inception. In this manuscript, we show that patient-to-patient variability sets a fundamental limit on outcome prediction accuracy for a general class of mathematical models for the immune response to infection. However, accuracy can be increased at the expense of delayed prognosis. We investigate several systems of ordinary differential equations (ODEs) that model the host immune response to a pathogen load. Advantages of systems of ODEs for investigating the immune response to infection include the ability to collect data on large numbers of 'virtual patients', each with a given set of model parameters, and obtain many time points during the course of the infection. We implement patient-to-patient variability v in the ODE models by randomly selecting the model parameters from distributions with coefficients of variation v that are centered on physiological values. We use logistic regression with one-versus-all classification to predict the discrete steady-state outcomes of the system. We find that the prediction algorithm achieves near 100% accuracy for v = 0, and the accuracy decreases with increasing v for all ODE models studied. The fact that multiple steady-state outcomes can be obtained for a given initial condition, i.e. the basins of attraction overlap in the space of initial conditions, limits the prediction accuracy for v > 0. Increasing the elapsed time of the variables used to train and test the classifier, increases the prediction accuracy, while adding explicit external noise to the ODE models decreases the prediction accuracy. Our results quantify the competition between early prognosis and high prediction accuracy that is frequently encountered by clinicians.

  11. 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…

  12. Response-only method for damage detection of beam-like structures using high accuracy frequencies with auxiliary mass spatial probing

    NASA Astrophysics Data System (ADS)

    Zhong, Shuncong; Oyadiji, S. Olutunde; Ding, Kang

    2008-04-01

    This paper proposes a new approach based on auxiliary mass spatial probing using spectral centre correction method (SCCM), to provide a simple solution for damage detection by just using the response time history of beam-like structures. The natural frequencies of a damaged beam with a traversing auxiliary mass change due to change in the inertia of the beam as the auxiliary mass is traversed along the beam, as well as the point-to-point variations in the flexibility of the beam. Therefore the auxiliary mass can enhance the effects of the crack on the dynamics of the beam and, therefore, facilitate the identification and location of damage in the beam. That is, the auxiliary mass can be used to probe the dynamic characteristic of the beam by traversing the mass from one end of the beam to the other. However, it is impossible to obtain accurate modal frequencies by the direct operation of the fast Fourier transform (FFT) of the response data of the structure because the frequency spectrum can be only calculated from limited sampled time data which results in the well-known leakage effect. SCCM is identical to the energy centrobaric correction method (ECCM) which is a practical and effective method used in rotating mechanical fault diagnosis and which resolves the shortcoming of FFT and can provide high accuracy estimate of frequency, amplitude and phase. In the present work, the modal responses of damaged simply supported beams with auxiliary mass are computed using the finite element method (FEM). The graphical plots of the natural frequencies calculated by SCCM versus axial location of auxiliary mass are obtained. However, it is difficult to locate the crack directly from the curve of natural frequencies. A simple and fast method, the derivatives of natural frequency curve, is proposed in the paper which can provide crack information for damage detection of beam-like structures. The efficiency and practicability of the proposed method is illustrated via numerical

  13. Continuous Glucose Monitoring and Trend Accuracy

    PubMed Central

    Gottlieb, Rebecca; Le Compte, Aaron; Chase, J. Geoffrey

    2014-01-01

    Continuous glucose monitoring (CGM) devices are being increasingly used to monitor glycemia in people with diabetes. One advantage with CGM is the ability to monitor the trend of sensor glucose (SG) over time. However, there are few metrics available for assessing the trend accuracy of CGM devices. The aim of this study was to develop an easy to interpret tool for assessing trend accuracy of CGM data. SG data from CGM were compared to hourly blood glucose (BG) measurements and trend accuracy was quantified using the dot product. Trend accuracy results are displayed on the Trend Compass, which depicts trend accuracy as a function of BG. A trend performance table and Trend Index (TI) metric are also proposed. The Trend Compass was tested using simulated CGM data with varying levels of error and variability, as well as real clinical CGM data. The results show that the Trend Compass is an effective tool for differentiating good trend accuracy from poor trend accuracy, independent of glycemic variability. Furthermore, the real clinical data show that the Trend Compass assesses trend accuracy independent of point bias error. Finally, the importance of assessing trend accuracy as a function of BG level is highlighted in a case example of low and falling BG data, with corresponding rising SG data. This study developed a simple to use tool for quantifying trend accuracy. The resulting trend accuracy is easily interpreted on the Trend Compass plot, and if required, performance table and TI metric. PMID:24876437

  14. On the accuracy of ERS-1 orbit predictions

    NASA Technical Reports Server (NTRS)

    Koenig, Rolf; Li, H.; Massmann, Franz-Heinrich; Raimondo, J. C.; Rajasenan, C.; Reigber, C.

    1993-01-01

    Since the launch of ERS-1, the D-PAF (German Processing and Archiving Facility) provides regularly orbit predictions for the worldwide SLR (Satellite Laser Ranging) tracking network. The weekly distributed orbital elements are so called tuned IRV's and tuned SAO-elements. The tuning procedure, designed to improve the accuracy of the recovery of the orbit at the stations, is discussed based on numerical results. This shows that tuning of elements is essential for ERS-1 with the currently applied tracking procedures. The orbital elements are updated by daily distributed time bias functions. The generation of the time bias function is explained. Problems and numerical results are presented. The time bias function increases the prediction accuracy considerably. Finally, the quality assessment of ERS-1 orbit predictions is described. The accuracy is compiled for about 250 days since launch. The average accuracy lies in the range of 50-100 ms and has considerably improved.

  15. Long time response of soft magnetorheological gels.

    PubMed

    An, Hai-Ning; Sun, Bin; Picken, Stephen J; Mendes, Eduardo

    2012-04-19

    Swollen physical magnetorheological (MR) gels were obtained by self-assembling of triblock copolymers containing dispersed soft magnetic particles. The transient rheological responses of these systems were investigated experimentally. Upon sudden application of a homogeneous magnetic field step change, the storage modulus of MR gels continued to increase with time. Such increase trend of the storage modulus could be expressed by a double-exponential function with two distinct modes, a fast and a slow one. The result was compared with the transient rheological response of equivalent MR fluids (paraffin oil without copolymer) and a MR elastomer (PDMS) and interpreted as the consequence of strong rearrangement of the original particle network under magnetic field. Similar to the structure evolution of MR fluids, the ensemble of results suggests that "chaining" and "clustering" processes are also happening inside the gel and are responsible for the rheological behavior, provided they are happening on a smaller length scale (long chains and clusters are hindered). We show that response times of several minutes are typical for the slow response of MR gels. The characteristic time t(2) for the slow process is significantly dependent on the magnetic flux density, the matrix viscoelastic property, particle volume fraction, and sample's initial particle distribution. In order to validate our results, the role of dynamic strain history was clarified. We show that, in the linear viscoelastic region, the particle rearrangement of MR gels was not hindered or accelerated by the dynamic strain history.

  16. A threshold-free summary index of prediction accuracy for censored time to event data.

    PubMed

    Yuan, Yan; Zhou, Qian M; Li, Bingying; Cai, Hengrui; Chow, Eric J; Armstrong, Gregory T

    2018-05-10

    Prediction performance of a risk scoring system needs to be carefully assessed before its adoption in clinical practice. Clinical preventive care often uses risk scores to screen asymptomatic population. The primary clinical interest is to predict the risk of having an event by a prespecified future time t 0 . Accuracy measures such as positive predictive values have been recommended for evaluating the predictive performance. However, for commonly used continuous or ordinal risk score systems, these measures require a subjective cutoff threshold value that dichotomizes the risk scores. The need for a cutoff value created barriers for practitioners and researchers. In this paper, we propose a threshold-free summary index of positive predictive values that accommodates time-dependent event status and competing risks. We develop a nonparametric estimator and provide an inference procedure for comparing this summary measure between 2 risk scores for censored time to event data. We conduct a simulation study to examine the finite-sample performance of the proposed estimation and inference procedures. Lastly, we illustrate the use of this measure on a real data example, comparing 2 risk score systems for predicting heart failure in childhood cancer survivors. Copyright © 2018 John Wiley & Sons, Ltd.

  17. Response rate, response time, and economic costs of survey research: A randomized trial of practicing pharmacists.

    PubMed

    Hardigan, Patrick C; Popovici, Ioana; Carvajal, Manuel J

    2016-01-01

    There is a gap between increasing demands from pharmacy journals, publishers, and reviewers for high survey response rates and the actual responses often obtained in the field by survey researchers. Presumably demands have been set high because response rates, times, and costs affect the validity and reliability of survey results. Explore the extent to which survey response rates, average response times, and economic costs are affected by conditions under which pharmacist workforce surveys are administered. A random sample of 7200 U.S. practicing pharmacists was selected. The sample was stratified by delivery method, questionnaire length, item placement, and gender of respondent for a total of 300 observations within each subgroup. A job satisfaction survey was administered during March-April 2012. Delivery method was the only classification showing significant differences in response rates and average response times. The postal mail procedure accounted for the highest response rates of completed surveys, but the email method exhibited the quickest turnaround. A hybrid approach, consisting of a combination of postal and electronic means, showed the least favorable results. Postal mail was 2.9 times more cost effective than the email approach and 4.6 times more cost effective than the hybrid approach. Researchers seeking to increase practicing pharmacists' survey participation and reduce response time and related costs can benefit from the analytical procedures tested here. Copyright © 2016 Elsevier Inc. All rights reserved.

  18. Improved Accuracy of Automated Estimation of Cardiac Output Using Circulation Time in Patients with Heart Failure.

    PubMed

    Dajani, Hilmi R; Hosokawa, Kazuya; Ando, Shin-Ichi

    2016-11-01

    Lung-to-finger circulation time of oxygenated blood during nocturnal periodic breathing in heart failure patients measured using polysomnography correlates negatively with cardiac function but possesses limited accuracy for cardiac output (CO) estimation. CO was recalculated from lung-to-finger circulation time using a multivariable linear model with information on age and average overnight heart rate in 25 patients who underwent evaluation of heart failure. The multivariable model decreased the percentage error to 22.3% relative to invasive CO measured during cardiac catheterization. This improved automated noninvasive CO estimation using multiple variables meets a recently proposed performance criterion for clinical acceptability of noninvasive CO estimation, and compares very favorably with other available methods. Copyright © 2016 Elsevier Inc. All rights reserved.

  19. The Impact of Strategy Instruction and Timing of Estimates on Low and High Working-Memory Capacity Readers' Absolute Monitoring Accuracy

    ERIC Educational Resources Information Center

    Linderholm, Tracy; Zhao, Qin

    2008-01-01

    Working-memory capacity, strategy instruction, and timing of estimates were investigated for their effects on absolute monitoring accuracy, which is the difference between estimated and actual reading comprehension test performance. Participants read two expository texts under one of two randomly assigned reading strategy instruction conditions…

  20. Lawsuit lead time prediction: Comparison of data mining techniques based on categorical response variable.

    PubMed

    Gruginskie, Lúcia Adriana Dos Santos; Vaccaro, Guilherme Luís Roehe

    2018-01-01

    The quality of the judicial system of a country can be verified by the overall length time of lawsuits, or the lead time. When the lead time is excessive, a country's economy can be affected, leading to the adoption of measures such as the creation of the Saturn Center in Europe. Although there are performance indicators to measure the lead time of lawsuits, the analysis and the fit of prediction models are still underdeveloped themes in the literature. To contribute to this subject, this article compares different prediction models according to their accuracy, sensitivity, specificity, precision, and F1 measure. The database used was from TRF4-the Tribunal Regional Federal da 4a Região-a federal court in southern Brazil, corresponding to the 2nd Instance civil lawsuits completed in 2016. The models were fitted using support vector machine, naive Bayes, random forests, and neural network approaches with categorical predictor variables. The lead time of the 2nd Instance judgment was selected as the response variable measured in days and categorized in bands. The comparison among the models showed that the support vector machine and random forest approaches produced measurements that were superior to those of the other models. The evaluation of the models was made using k-fold cross-validation similar to that applied to the test models.

  1. Linear Discriminant Analysis Achieves High Classification Accuracy for the BOLD fMRI Response to Naturalistic Movie Stimuli

    PubMed Central

    Mandelkow, Hendrik; de Zwart, Jacco A.; Duyn, Jeff H.

    2016-01-01

    Naturalistic stimuli like movies evoke complex perceptual processes, which are of great interest in the study of human cognition by functional MRI (fMRI). However, conventional fMRI analysis based on statistical parametric mapping (SPM) and the general linear model (GLM) is hampered by a lack of accurate parametric models of the BOLD response to complex stimuli. In this situation, statistical machine-learning methods, a.k.a. multivariate pattern analysis (MVPA), have received growing attention for their ability to generate stimulus response models in a data-driven fashion. However, machine-learning methods typically require large amounts of training data as well as computational resources. In the past, this has largely limited their application to fMRI experiments involving small sets of stimulus categories and small regions of interest in the brain. By contrast, the present study compares several classification algorithms known as Nearest Neighbor (NN), Gaussian Naïve Bayes (GNB), and (regularized) Linear Discriminant Analysis (LDA) in terms of their classification accuracy in discriminating the global fMRI response patterns evoked by a large number of naturalistic visual stimuli presented as a movie. Results show that LDA regularized by principal component analysis (PCA) achieved high classification accuracies, above 90% on average for single fMRI volumes acquired 2 s apart during a 300 s movie (chance level 0.7% = 2 s/300 s). The largest source of classification errors were autocorrelations in the BOLD signal compounded by the similarity of consecutive stimuli. All classifiers performed best when given input features from a large region of interest comprising around 25% of the voxels that responded significantly to the visual stimulus. Consistent with this, the most informative principal components represented widespread distributions of co-activated brain regions that were similar between subjects and may represent functional networks. In light of these

  2. Developing a weighted measure of speech sound accuracy.

    PubMed

    Preston, Jonathan L; Ramsdell, Heather L; Oller, D Kimbrough; Edwards, Mary Louise; Tobin, Stephen J

    2011-02-01

    To develop a system for numerically quantifying a speaker's phonetic accuracy through transcription-based measures. With a focus on normal and disordered speech in children, the authors describe a system for differentially weighting speech sound errors on the basis of various levels of phonetic accuracy using a Weighted Speech Sound Accuracy (WSSA) score. The authors then evaluate the reliability and validity of this measure. Phonetic transcriptions were analyzed from several samples of child speech, including preschoolers and young adolescents with and without speech sound disorders and typically developing toddlers. The new measure of phonetic accuracy was validated against existing measures, was used to discriminate typical and disordered speech production, and was evaluated to examine sensitivity to changes in phonetic accuracy over time. Reliability between transcribers and consistency of scores among different word sets and testing points are compared. Initial psychometric data indicate that WSSA scores correlate with other measures of phonetic accuracy as well as listeners' judgments of the severity of a child's speech disorder. The measure separates children with and without speech sound disorders and captures growth in phonetic accuracy in toddlers' speech over time. The measure correlates highly across transcribers, word lists, and testing points. Results provide preliminary support for the WSSA as a valid and reliable measure of phonetic accuracy in children's speech.

  3. A New Procedure for Detection of Students' Rapid Guessing Responses Using Response Time

    ERIC Educational Resources Information Center

    Guo, Hongwen; Rios, Joseph A.; Haberman, Shelby; Liu, Ou Lydia; Wang, Jing; Paek, Insu

    2016-01-01

    Unmotivated test takers using rapid guessing in item responses can affect validity studies and teacher and institution performance evaluation negatively, making it critical to identify these test takers. The authors propose a new nonparametric method for finding response-time thresholds for flagging item responses that result from rapid-guessing…

  4. Response time as a discriminator between true- and false-positive responses in suprathreshold perimetry.

    PubMed

    Artes, Paul H; McLeod, David; Henson, David B

    2002-01-01

    To report on differences between the latency distributions of responses to stimuli and to false-positive catch trials in suprathreshold perimetry. To describe an algorithm for defining response time windows and to report on its performance in discriminating between true- and false-positive responses on the basis of response time (RT). A sample of 435 largely inexperienced patients underwent suprathreshold visual field examination on a perimeter that was modified to record RTs. Data were analyzed from 60,500 responses to suprathreshold stimuli and from 523 false-positive responses to catch trials. False-positive responses had much more variable latencies than responses to suprathreshold stimuli. An algorithm defining RT windows on the basis of z-transformed individual latency samples correctly identified more than 70% of false-positive responses to catch trials, whereas fewer than 3% of responses to suprathreshold stimuli were classified as false-positive responses. Latency analysis can be used to detect a substantial proportion of false-positive responses in suprathreshold perimetry. Rejection of such responses may increase the reliability of visual field screening by reducing variability and bias in a small but clinically important proportion of patients.

  5. 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.

  6. 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

  7. [Medial Unicompartmental Knee Arthroplasty Using Patient-Specific Instrumentation - Accuracy of Preoperative Planning, Time Saving and Cost Efficiency].

    PubMed

    Seeber, G H; Kolbow, K; Maus, U; Kluge, A; Lazovic, D

    2016-06-01

    In the past few years, patient-specific instrumentation (PSI) in knee endoprosthetics has been energetically marketed. PSI can enhance the accuracy of the size and alignment of the prosthesis components. It should also be possible to reduce hospital costs and operating time. It remains unclear whether these putative advantages are achieved in medial unicompartmental knee arthroplasty (UKA). Data from 22 patients (24 knees) were analysed retrospectively. The focus was on the reliability of preoperative surgical planning - particularly with regards to the level of experience of the five surgeons involved, who were split into two groups depending on their level of experience, as defined by EndoCert®. Another focus was on the evaluation of actual surgical time and cost effectiveness using PSI. In order to achieve an optimal outcome, preoperative surgical planning had to be modified intraoperatively to a great extent. The femoral component had to be adjusted intraoperatively in 41.7 % of all cases, the tibial component in 58.3 % and the polyethylene insert in 87.5 %. Surgeons equipped with less experience had to change preoperative planning more often than the more experienced surgeons. Utilising PSI increased the operating time of both the less experienced and the more experienced surgeons. PSI planning and lack of surgical experience were the main predictors of increased surgical time. Instead of lowering costs, utilizing PSI increased surgical costs by nearly 1300 $ per case. This was due to increased operating time, license fees and extraordinary expenditure for MRI scans. The advertised advantages of PSI were not supported by the data analysed. On the contrary, this technology leads to additional costs, greater operating time and insufficient accuracy in preoperative planning. As not a single study has yet demonstrated better outcomes in terms of alignment and/or function with PSI than with standard instrumentation, additional data are required before PSI

  8. Lexical and Sub-Lexical Effects on Accuracy, Reaction Time and Response Duration: Impaired and Typical Word and Pseudoword Reading in a Transparent Orthography

    ERIC Educational Resources Information Center

    Davies, Robert; Rodriguez-Ferreiro, Javier; Suarez, Paz; Cuetos, Fernando

    2013-01-01

    In an opaque orthography like English, phonological coding errors are a prominent feature of dyslexia. In a transparent orthography like Spanish, reading difficulties are characterized by slower reading speed rather than reduced accuracy. In previous research, the reading speed deficit was revealed by asking children to read lists of words.…

  9. 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.

  10. 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.

  11. Improving the accuracy and efficiency of time-resolved electronic spectra calculations: cellular dephasing representation with a prefactor.

    PubMed

    Zambrano, Eduardo; Šulc, Miroslav; Vaníček, Jiří

    2013-08-07

    Time-resolved electronic spectra can be obtained as the Fourier transform of a special type of time correlation function known as fidelity amplitude, which, in turn, can be evaluated approximately and efficiently with the dephasing representation. Here we improve both the accuracy of this approximation-with an amplitude correction derived from the phase-space propagator-and its efficiency-with an improved cellular scheme employing inverse Weierstrass transform and optimal scaling of the cell size. We demonstrate the advantages of the new methodology by computing dispersed time-resolved stimulated emission spectra in the harmonic potential, pyrazine, and the NCO molecule. In contrast, we show that in strongly chaotic systems such as the quartic oscillator the original dephasing representation is more appropriate than either the cellular or prefactor-corrected methods.

  12. Peripheral visual response time and visual display layout

    NASA Technical Reports Server (NTRS)

    Haines, R. F.

    1974-01-01

    Experiments were performed on a group of 42 subjects in a study of their peripheral visual response time to visual signals under positive acceleration, during prolonged bedrest, at passive 70 deg headup body lift, under exposures to high air temperatures and high luminance levels, and under normal stress-free laboratory conditions. Diagrams are plotted for mean response times to white, red, yellow, green, and blue stimuli under different conditions.

  13. Time Course of Visual Extrapolation Accuracy

    DTIC Science & Technology

    1995-09-01

    The pond and duckweed problem: Three experiments on the misperception of exponential growth . Acta Psychologica 43, 239-251. Wiener, E.L., 1962...random variation in tracker velocity. Both models predicted changes in hit and false alarm rates well, except in a condition where response asymmetries...systematic velocity error in tracking, only random variation in tracker velocity. Both models predicted changes in hit and false alarm rates well

  14. 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

  15. Improving Precision, Maintaining Accuracy, and Reducing Acquisition Time for Trace Elements in EPMA

    NASA Astrophysics Data System (ADS)

    Donovan, J.; Singer, J.; Armstrong, J. T.

    2016-12-01

    Trace element precision in electron probe micro analysis (EPMA) is limited by intrinsic random variation in the x-ray continuum. Traditionally we characterize background intensity by measuring on either side of the emission line and interpolating the intensity underneath the peak to obtain the net intensity. Alternatively, we can measure the background intensity at the on-peak spectrometer position using a number of standard materials that do not contain the element of interest. This so-called mean atomic number (MAN) background calibration (Donovan, et al., 2016) uses a set of standard measurements, covering an appropriate range of average atomic number, to iteratively estimate the continuum intensity for the unknown composition (and hence average atomic number). We will demonstrate that, at least for materials with a relatively simple matrix such as SiO2, TiO2, ZrSiO4, etc. where one may obtain a matrix matched standard for use in the so called "blank correction", we can obtain trace element accuracy comparable to traditional off-peak methods, and with improved precision, in about half the time. Donovan, Singer and Armstrong, A New EPMA Method for Fast Trace Element Analysis in Simple Matrices ", American Mineralogist, v101, p1839-1853, 2016 Figure 1. Uranium concentration line profiles from quantitative x-ray maps (20 keV, 100 nA, 5 um beam size and 4000 msec per pixel), for both off-peak and MAN background methods without (a), and with (b), the blank correction applied. We see precision significantly improved compared with traditional off-peak measurements while, in this case, the blank correction provides a small but discernable improvement in accuracy.

  16. Prefrontal Consolidation Supports the Attainment of Fear Memory Accuracy

    ERIC Educational Resources Information Center

    Vieira, Philip A.; Lovelace, Jonathan W.; Corches, Alex; Rashid, Asim J.; Josselyn, Sheena A.; Korzus, Edward

    2014-01-01

    The neural mechanisms underlying the attainment of fear memory accuracy for appropriate discriminative responses to aversive and nonaversive stimuli are unclear. Considerable evidence indicates that coactivator of transcription and histone acetyltransferase cAMP response element binding protein (CREB) binding protein (CBP) is critically required…

  17. Real-time positioning in logging: Effects of forest stand characteristics, topography, and line-of-sight obstructions on GNSS-RF transponder accuracy and radio signal propagation.

    PubMed

    Zimbelman, Eloise G; Keefe, Robert F

    2018-01-01

    Real-time positioning on mobile devices using global navigation satellite system (GNSS) technology paired with radio frequency (RF) transmission (GNSS-RF) may help to improve safety on logging operations by increasing situational awareness. However, GNSS positional accuracy for ground workers in motion may be reduced by multipath error, satellite signal obstruction, or other factors. Radio propagation of GNSS locations may also be impacted due to line-of-sight (LOS) obstruction in remote, forested areas. The objective of this study was to characterize the effects of forest stand characteristics, topography, and other LOS obstructions on the GNSS accuracy and radio signal propagation quality of multiple Raveon Atlas PT GNSS-RF transponders functioning as a network in a range of forest conditions. Because most previous research with GNSS in forestry has focused on stationary units, we chose to analyze units in motion by evaluating the time-to-signal accuracy of geofence crossings in 21 randomly-selected stands on the University of Idaho Experimental Forest. Specifically, we studied the effects of forest stand characteristics, topography, and LOS obstructions on (1) the odds of missed GNSS-RF signals, (2) the root mean squared error (RMSE) of Atlas PTs, and (3) the time-to-signal accuracy of safety geofence crossings in forested environments. Mixed-effects models used to analyze the data showed that stand characteristics, topography, and obstructions in the LOS affected the odds of missed radio signals while stand variables alone affected RMSE. Both stand characteristics and topography affected the accuracy of geofence alerts.

  18. Real-time positioning in logging: Effects of forest stand characteristics, topography, and line-of-sight obstructions on GNSS-RF transponder accuracy and radio signal propagation

    PubMed Central

    2018-01-01

    Real-time positioning on mobile devices using global navigation satellite system (GNSS) technology paired with radio frequency (RF) transmission (GNSS-RF) may help to improve safety on logging operations by increasing situational awareness. However, GNSS positional accuracy for ground workers in motion may be reduced by multipath error, satellite signal obstruction, or other factors. Radio propagation of GNSS locations may also be impacted due to line-of-sight (LOS) obstruction in remote, forested areas. The objective of this study was to characterize the effects of forest stand characteristics, topography, and other LOS obstructions on the GNSS accuracy and radio signal propagation quality of multiple Raveon Atlas PT GNSS-RF transponders functioning as a network in a range of forest conditions. Because most previous research with GNSS in forestry has focused on stationary units, we chose to analyze units in motion by evaluating the time-to-signal accuracy of geofence crossings in 21 randomly-selected stands on the University of Idaho Experimental Forest. Specifically, we studied the effects of forest stand characteristics, topography, and LOS obstructions on (1) the odds of missed GNSS-RF signals, (2) the root mean squared error (RMSE) of Atlas PTs, and (3) the time-to-signal accuracy of safety geofence crossings in forested environments. Mixed-effects models used to analyze the data showed that stand characteristics, topography, and obstructions in the LOS affected the odds of missed radio signals while stand variables alone affected RMSE. Both stand characteristics and topography affected the accuracy of geofence alerts. PMID:29324794

  19. A Bivariate Generalized Linear Item Response Theory Modeling Framework to the Analysis of Responses and Response Times.

    PubMed

    Molenaar, Dylan; Tuerlinckx, Francis; van der Maas, Han L J

    2015-01-01

    A generalized linear modeling framework to the analysis of responses and response times is outlined. In this framework, referred to as bivariate generalized linear item response theory (B-GLIRT), separate generalized linear measurement models are specified for the responses and the response times that are subsequently linked by cross-relations. The cross-relations can take various forms. Here, we focus on cross-relations with a linear or interaction term for ability tests, and cross-relations with a curvilinear term for personality tests. In addition, we discuss how popular existing models from the psychometric literature are special cases in the B-GLIRT framework depending on restrictions in the cross-relation. This allows us to compare existing models conceptually and empirically. We discuss various extensions of the traditional models motivated by practical problems. We also illustrate the applicability of our approach using various real data examples, including data on personality and cognitive ability.

  20. On the Relationship Between Transfer Function-derived Response Times and Hydrograph Analysis Timing Parameters: Are there Similarities?

    NASA Astrophysics Data System (ADS)

    Bansah, S.; Ali, G.; Haque, M. A.; Tang, V.

    2017-12-01

    The proportion of precipitation that becomes streamflow is a function of internal catchment characteristics - which include geology, landscape characteristics and vegetation - and influence overall storage dynamics. The timing and quantity of water discharged by a catchment are indeed embedded in event hydrographs. Event hydrograph timing parameters, such as the response lag and time of concentration, are important descriptors of how long it takes the catchment to respond to input precipitation and how long it takes the latter to filter through the catchment. However, the extent to which hydrograph timing parameters relate to average response times derived from fitting transfer functions to annual hydrographs is unknown. In this study, we used a gamma transfer function to determine catchment average response times as well as event-specific hydrograph parameters across a network of eight nested watersheds ranging from 0.19 km2 to 74.6 km2 prairie catchments located in south central Manitoba (Canada). Various statistical analyses were then performed to correlate average response times - estimated using the parameters of the fitted gamma transfer function - to event-specific hydrograph parameters. Preliminary results show significant interannual variations in response times and hydrograph timing parameters: the former were in the order of a few hours to days, while the latter ranged from a few days to weeks. Some statistically significant relationships were detected between response times and event-specific hydrograph parameters. Future analyses will involve the comparison of statistical distributions of event-specific hydrograph parameters with that of runoff response times and baseflow transit times in order to quantity catchment storage dynamics across a range of temporal scales.

  1. 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…

  2. Co-acting gene networks predict TRAIL responsiveness of tumour cells with high accuracy.

    PubMed

    O'Reilly, Paul; Ortutay, Csaba; Gernon, Grainne; O'Connell, Enda; Seoighe, Cathal; Boyce, Susan; Serrano, Luis; Szegezdi, Eva

    2014-12-19

    Identification of differentially expressed genes from transcriptomic studies is one of the most common mechanisms to identify tumor biomarkers. This approach however is not well suited to identify interaction between genes whose protein products potentially influence each other, which limits its power to identify molecular wiring of tumour cells dictating response to a drug. Due to the fact that signal transduction pathways are not linear and highly interlinked, the biological response they drive may be better described by the relative amount of their components and their functional relationships than by their individual, absolute expression. Gene expression microarray data for 109 tumor cell lines with known sensitivity to the death ligand cytokine tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) was used to identify genes with potential functional relationships determining responsiveness to TRAIL-induced apoptosis. The machine learning technique Random Forest in the statistical environment "R" with backward elimination was used to identify the key predictors of TRAIL sensitivity and differentially expressed genes were identified using the software GeneSpring. Gene co-regulation and statistical interaction was assessed with q-order partial correlation analysis and non-rejection rate. Biological (functional) interactions amongst the co-acting genes were studied with Ingenuity network analysis. Prediction accuracy was assessed by calculating the area under the receiver operator curve using an independent dataset. We show that the gene panel identified could predict TRAIL-sensitivity with a very high degree of sensitivity and specificity (AUC=0·84). The genes in the panel are co-regulated and at least 40% of them functionally interact in signal transduction pathways that regulate cell death and cell survival, cellular differentiation and morphogenesis. Importantly, only 12% of the TRAIL-predictor genes were differentially expressed highlighting the

  3. 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

  4. Enhanced Response Time of Electrowetting Lenses with Shaped Input Voltage Functions.

    PubMed

    Supekar, Omkar D; Zohrabi, Mo; Gopinath, Juliet T; Bright, Victor M

    2017-05-16

    Adaptive optical lenses based on the electrowetting principle are being rapidly implemented in many applications, such as microscopy, remote sensing, displays, and optical communication. To characterize the response of these electrowetting lenses, the dependence upon direct current (DC) driving voltage functions was investigated in a low-viscosity liquid system. Cylindrical lenses with inner diameters of 2.45 and 3.95 mm were used to characterize the dynamic behavior of the liquids under DC voltage electrowetting actuation. With the increase of the rise time of the input exponential driving voltage, the originally underdamped system response can be damped, enabling a smooth response from the lens. We experimentally determined the optimal rise times for the fastest response from the lenses. We have also performed numerical simulations of the lens actuation with input exponential driving voltage to understand the variation in the dynamics of the liquid-liquid interface with various input rise times. We further enhanced the response time of the devices by shaping the input voltage function with multiple exponential rise times. For the 3.95 mm inner diameter lens, we achieved a response time improvement of 29% when compared to the fastest response obtained using single-exponential driving voltage. The technique shows great promise for applications that require fast response times.

  5. 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

  6. A Classical Based Derivation of Time Dilation Providing First Order Accuracy to Schwarzschild's Solution of Einstein's Field Equations

    NASA Astrophysics Data System (ADS)

    Austin, Rickey W.

    In Einstein's theory of Special Relativity (SR), one method to derive relativistic kinetic energy is via applying the classical work-energy theorem to relativistic momentum. This approach starts with a classical based work-energy theorem and applies SR's momentum to the derivation. One outcome of this derivation is relativistic kinetic energy. From this derivation, it is rather straight forward to form a kinetic energy based time dilation function. In the derivation of General Relativity a common approach is to bypass classical laws as a starting point. Instead a rigorous development of differential geometry and Riemannian space is constructed, from which classical based laws are derived. This is in contrast to SR's approach of starting with classical laws and applying the consequences of the universal speed of light by all observers. A possible method to derive time dilation due to Newtonian gravitational potential energy (NGPE) is to apply SR's approach to deriving relativistic kinetic energy. It will be shown this method gives a first order accuracy compared to Schwarzschild's metric. The SR's kinetic energy and the newly derived NGPE derivation are combined to form a Riemannian metric based on these two energies. A geodesic is derived and calculations compared to Schwarzschild's geodesic for an orbiting test mass about a central, non-rotating, non-charged massive body. The new metric results in high accuracy calculations when compared to Einsteins General Relativity's prediction. The new method provides a candidate approach for starting with classical laws and deriving General Relativity effects. This approach mimics SR's method of starting with classical mechanics when deriving relativistic equations. As a compliment to introducing General Relativity, it provides a plausible scaffolding method from classical physics when teaching introductory General Relativity. A straight forward path from classical laws to General Relativity will be derived. This derivation

  7. 6 CFR 5.5 - Timing of responses to requests.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 6 Domestic Security 1 2010-01-01 2010-01-01 false Timing of responses to requests. 5.5 Section 5.5 Domestic Security DEPARTMENT OF HOMELAND SECURITY, OFFICE OF THE SECRETARY DISCLOSURE OF RECORDS AND INFORMATION Freedom of Information Act § 5.5 Timing of responses to requests. (a) In general. Components...

  8. Reversing the picture superiority effect: a speed-accuracy trade-off study of recognition memory.

    PubMed

    Boldini, Angela; Russo, Riccardo; Punia, Sahiba; Avons, S E

    2007-01-01

    Speed-accuracy trade-off methods have been used to contrast single- and dual-process accounts of recognition memory. With these procedures, subjects are presented with individual test items and required to make recognition decisions under various time constraints. In three experiments, we presented words and pictures to be intentionally learned; test stimuli were always visually presented words. At test, we manipulated the interval between the presentation of each test stimulus and that of a response signal, thus controlling the amount of time available to retrieve target information. The standard picture superiority effect was significant in long response deadline conditions (i.e., > or = 2,000 msec). Conversely, a significant reverse picture superiority effect emerged at short response-signal deadlines (< 200 msec). The results are congruent with views suggesting that both fast familiarity and slower recollection processes contribute to recognition memory. Alternative accounts are also discussed.

  9. Uncertainty analysis of accident notification time and emergency medical service response time in work zone traffic accidents.

    PubMed

    Meng, Qiang; Weng, Jinxian

    2013-01-01

    Taking into account the uncertainty caused by exogenous factors, the accident notification time (ANT) and emergency medical service (EMS) response time were modeled as 2 random variables following the lognormal distribution. Their mean values and standard deviations were respectively formulated as the functions of environmental variables including crash time, road type, weekend, holiday, light condition, weather, and work zone type. Work zone traffic accident data from the Fatality Analysis Report System between 2002 and 2009 were utilized to determine the distributions of the ANT and the EMS arrival time in the United States. A mixed logistic regression model, taking into account the uncertainty associated with the ANT and the EMS response time, was developed to estimate the risk of death. The results showed that the uncertainty of the ANT was primarily influenced by crash time and road type, whereas the uncertainty of EMS response time is greatly affected by road type, weather, and light conditions. In addition, work zone accidents occurring during a holiday and in poor light conditions were found to be statistically associated with a longer mean ANT and longer EMS response time. The results also show that shortening the ANT was a more effective approach in reducing the risk of death than the EMS response time in work zones. To shorten the ANT and the EMS response time, work zone activities are suggested to be undertaken during non-holidays, during the daytime, and in good weather and light conditions.

  10. Improved accuracies for satellite tracking

    NASA Technical Reports Server (NTRS)

    Kammeyer, P. C.; Fiala, A. D.; Seidelmann, P. K.

    1991-01-01

    A charge coupled device (CCD) camera on an optical telescope which follows the stars can be used to provide high accuracy comparisons between the line of sight to a satellite, over a large range of satellite altitudes, and lines of sight to nearby stars. The CCD camera can be rotated so the motion of the satellite is down columns of the CCD chip, and charge can be moved from row to row of the chip at a rate which matches the motion of the optical image of the satellite across the chip. Measurement of satellite and star images, together with accurate timing of charge motion, provides accurate comparisons of lines of sight. Given lines of sight to stars near the satellite, the satellite line of sight may be determined. Initial experiments with this technique, using an 18 cm telescope, have produced TDRS-4 observations which have an rms error of 0.5 arc second, 100 m at synchronous altitude. Use of a mosaic of CCD chips, each having its own rate of charge motion, in the focal place of a telescope would allow point images of a geosynchronous satellite and of stars to be formed simultaneously in the same telescope. The line of sight of such a satellite could be measured relative to nearby star lines of sight with an accuracy of approximately 0.03 arc second. Development of a star catalog with 0.04 arc second rms accuracy and perhaps ten stars per square degree would allow determination of satellite lines of sight with 0.05 arc second rms absolute accuracy, corresponding to 10 m at synchronous altitude. Multiple station time transfers through a communications satellite can provide accurate distances from the satellite to the ground stations. Such observations can, if calibrated for delays, determine satellite orbits to an accuracy approaching 10 m rms.

  11. 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.

  12. Improvement of Accuracy in Environmental Dosimetry by TLD Cards Using Three-dimensional Calibration Method.

    PubMed

    HosseiniAliabadi, S J; Hosseini Pooya, S M; Afarideh, H; Mianji, F

    2015-06-01

    The angular dependency of response for TLD cards may cause deviation from its true value on the results of environmental dosimetry, since TLDs may be exposed to radiation at different angles of incidence from the surrounding area. A 3D setting of TLD cards has been calibrated isotropically in a standard radiation field to evaluate the improvement of the accuracy of measurement for environmental dosimetry. Three personal TLD cards were rectangularly placed in a cylindrical holder, and calibrated using 1D and 3D calibration methods. Then, the dosimeter has been used simultaneously with a reference instrument in a real radiation field measuring the accumulated dose within a time interval. The results show that the accuracy of measurement has been improved by 6.5% using 3D calibration factor in comparison with that of normal 1D calibration method. This system can be utilized in large scale environmental monitoring with a higher accuracy.

  13. Improvement of Accuracy in Environmental Dosimetry by TLD Cards Using Three-dimensional Calibration Method

    PubMed Central

    HosseiniAliabadi, S. J.; Hosseini Pooya, S. M.; Afarideh, H.; Mianji, F.

    2015-01-01

    Introduction The angular dependency of response for TLD cards may cause deviation from its true value on the results of environmental dosimetry, since TLDs may be exposed to radiation at different angles of incidence from the surrounding area. Objective A 3D setting of TLD cards has been calibrated isotropically in a standard radiation field to evaluate the improvement of the accuracy of measurement for environmental dosimetry. Method Three personal TLD cards were rectangularly placed in a cylindrical holder, and calibrated using 1D and 3D calibration methods. Then, the dosimeter has been used simultaneously with a reference instrument in a real radiation field measuring the accumulated dose within a time interval. Result The results show that the accuracy of measurement has been improved by 6.5% using 3D calibration factor in comparison with that of normal 1D calibration method. Conclusion This system can be utilized in large scale environmental monitoring with a higher accuracy. PMID:26157729

  14. Emergency Department Length of Stay: Accuracy of Patient Estimates

    PubMed Central

    Parker, Brendan T.; Marco, Catherine

    2014-01-01

    Introduction Managing a patient’s expectations in the emergency department (ED) environment is challenging. Previous studies have identified several factors associated with ED patient satisfaction. Lengthy wait times have shown to be associated with dissatisfaction with ED care. Understanding that patients are inaccurate at their estimation of wait time, which could lead to lower satisfaction, provides administrators possible points of intervention to help improve accuracy of estimation and possibly satisfaction with the ED. This study was undertaken to examine the accuracy of patient estimates of time periods in an ED and identify factors associated with accuracy. Method In this prospective convenience sample survey at UTMC ED, we collected data between March and July 2012. Outcome measures included duration of each phase of ED care and patient estimates of these time periods. Results Among 309 participants, the majority underestimated the total length of stay (LOS) in the ED (median difference −7 minutes (IQR −29-12)). There was significant variability in ED LOS (median 155 minutes (IQR 75–240)). No significant associations were identified between accuracy of time estimates and gender, age, race, or insurance status. Participants with longer ED LOS demonstrated lower patient satisfaction scores (p<0.001). Conclusion Patients demonstrated inaccurate time estimates of ED treatment times, including total LOS. Patients with longer ED LOS had lower patient satisfaction scores. PMID:24672606

  15. Measuring older adults' sedentary time: reliability, validity, and responsiveness.

    PubMed

    Gardiner, Paul A; Clark, Bronwyn K; Healy, Genevieve N; Eakin, Elizabeth G; Winkler, Elisabeth A H; Owen, Neville

    2011-11-01

    With evidence that prolonged sitting has deleterious health consequences, decreasing sedentary time is a potentially important preventive health target. High-quality measures, particularly for use with older adults, who are the most sedentary population group, are needed to evaluate the effect of sedentary behavior interventions. We examined the reliability, validity, and responsiveness to change of a self-report sedentary behavior questionnaire that assessed time spent in behaviors common among older adults: watching television, computer use, reading, socializing, transport and hobbies, and a summary measure (total sedentary time). In the context of a sedentary behavior intervention, nonworking older adults (n = 48, age = 73 ± 8 yr (mean ± SD)) completed the questionnaire on three occasions during a 2-wk period (7 d between administrations) and wore an accelerometer (ActiGraph model GT1M) for two periods of 6 d. Test-retest reliability (for the individual items and the summary measure) and validity (self-reported total sedentary time compared with accelerometer-derived sedentary time) were assessed during the 1-wk preintervention period, using Spearman (ρ) correlations and 95% confidence intervals (CI). Responsiveness to change after the intervention was assessed using the responsiveness statistic (RS). Test-retest reliability was excellent for television viewing time (ρ (95% CI) = 0.78 (0.63-0.89)), computer use (ρ (95% CI) = 0.90 (0.83-0.94)), and reading (ρ (95% CI) = 0.77 (0.62-0.86)); acceptable for hobbies (ρ (95% CI) = 0.61 (0.39-0.76)); and poor for socializing and transport (ρ < 0.45). Total sedentary time had acceptable test-retest reliability (ρ (95% CI) = 0.52 (0.27-0.70)) and validity (ρ (95% CI) = 0.30 (0.02-0.54)). Self-report total sedentary time was similarly responsive to change (RS = 0.47) as accelerometer-derived sedentary time (RS = 0.39). The summary measure of total sedentary time has good repeatability and modest validity and is

  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. 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. 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

  19. Children’s Processing and Comprehension of Complex Sentences Containing Temporal Connectives: The Influence of Memory on the Time Course of Accurate Responses

    PubMed Central

    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 of events: “She drank the juice, before she walked in the park” (chronological order) versus “Before she walked in the park, she drank the juice” (reverse order). Differences in RTs for correct responses varied by sentence type: accurate responses were made more speedily for sentences that afforded an incremental processing of meaning. An independent measure of memory predicted this pattern of performance. We discuss these findings in relation to children’s knowledge of connective meaning and the processing requirements of sentences containing temporal connectives. PMID:27690492

  20. Selective processing of auditory evoked responses with iterative-randomized stimulation and averaging: A strategy for evaluating the time-invariant assumption.

    PubMed

    Valderrama, Joaquin T; de la Torre, Angel; Medina, Carlos; Segura, Jose C; Thornton, A Roger D

    2016-03-01

    The recording of auditory evoked potentials (AEPs) at fast rates allows the study of neural adaptation, improves accuracy in estimating hearing threshold and may help diagnosing certain pathologies. Stimulation sequences used to record AEPs at fast rates require to be designed with a certain jitter, i.e., not periodical. Some authors believe that stimuli from wide-jittered sequences may evoke auditory responses of different morphology, and therefore, the time-invariant assumption would not be accomplished. This paper describes a methodology that can be used to analyze the time-invariant assumption in jittered stimulation sequences. The proposed method [Split-IRSA] is based on an extended version of the iterative randomized stimulation and averaging (IRSA) technique, including selective processing of sweeps according to a predefined criterion. The fundamentals, the mathematical basis and relevant implementation guidelines of this technique are presented in this paper. The results of this study show that Split-IRSA presents an adequate performance and that both fast and slow mechanisms of adaptation influence the evoked-response morphology, thus both mechanisms should be considered when time-invariance is assumed. The significance of these findings is discussed. Crown Copyright © 2016. Published by Elsevier B.V. All rights reserved.

  1. 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,…

  2. Effect of N-acetylcysteine on the accuracy of the prothrombin time assay of plasma coagulation factor II+VII+X activity in subjects infused with the drug. Influence of time and temperature.

    PubMed

    Thorsen, Sixtus; Teisner, Ane; Jensen, Søren Astrup; Philips, Malou; Dalhoff, Kim; Bendtsen, Flemming

    2009-01-01

    The prothrombin time (PT) assay of factor II+VII+X activity is an important predictor of liver damage in paracetamol poisoned patients. It complicates interpretation of results that the antidote, acetylcysteine (NAC) depresses this activity. The aim was to investigate if NAC influences the accuracy of the plasma PT assay. The accuracy of Nycotest PT was studied using plasma added NAC in vitro and plasma from subjects infused with NAC. The latter results were compared with those obtained by analysis of PT by CoaguChek S. Therapeutic NAC concentrations added to plasma in vitro decreased factor II+VII+X activity at 37 degrees C in a time-dependent manner. This effect was quenched at temperatures <24 degrees C. Activity lost at 37 degrees C could partly be recovered by subsequent incubation at 5 or 20 degrees C. Incubation at 37 degrees C prior to assay led to a significant additional depression of factor II+VII+X activity in plasma from subjects infused with NAC during the first 3h of infusion indicating that it contained reactive NAC. The risk that this NAC interfered with the accuracy of the PT assay was considered minimal with samples stored below 24 degrees C. This was supported by similarity of results obtained by analysis of appropriately stored plasma and simultaneously drawn blood by CoaguChek S. Residual reactive NAC does not interfere with the accuracy of the PT assay of plasma stored below 24 degrees C, but NAC-induced loss in activity at 37 degrees C may be partly recovered during subsequent storage below 24 degrees C.

  3. Targeting Accuracy, Procedure Times and User Experience of 240 Experimental MRI Biopsies Guided by a Clinical Add-On Navigation System.

    PubMed

    Busse, Harald; Riedel, Tim; Garnov, Nikita; Thörmer, Gregor; Kahn, Thomas; Moche, Michael

    2015-01-01

    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. 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). 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). 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 groups with different expertise there were

  4. 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

  5. Combining Reaction Time and Accuracy: The Relationship Between Working Memory Capacity and Task Switching as a Case Example.

    PubMed

    Draheim, Christopher; Hicks, Kenny L; Engle, Randall W

    2016-01-01

    It is generally agreed upon that the mechanisms underlying task switching heavily depend on working memory, yet numerous studies have failed to show a strong relationship between working memory capacity (WMC) and task-switching ability. We argue that this relationship does indeed exist but that the dependent variable used to measure task switching is problematic. To support our claim, we reanalyzed data from two studies with a new scoring procedure that combines reaction time (RT) and accuracy into a single score. The reanalysis revealed a strong relationship between task switching and WMC that was not present when RT-based switch costs were used as the dependent variable. We discuss the theoretical implications of this finding along with the potential uses and limitations of the scoring procedure we used. More broadly, we emphasize the importance of using measures that incorporate speed and accuracy in other areas of research, particularly in comparisons of subjects differing in cognitive and developmental levels. © The Author(s) 2015.

  6. 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…

  7. [Construction of the Time Management Scale and examination of the influence of time management on psychological stress response].

    PubMed

    Imura, Tomoya; Takamura, Masahiro; Okazaki, Yoshihiro; Tokunaga, Satoko

    2016-10-01

    We developed a scale to measure time management and assessed its reliability and validity. We then used this scale to examine the impact of time management on psychological stress response. In Study 1-1, we developed the scale and assessed its internal consistency and criterion-related validity. Findings from a factor analysis revealed three elements of time management, “time estimation,” “time utilization,” and “taking each moment as it comes.” In Study 1-2, we assessed the scale’s test-retest reliability. In Study 1-3, we assessed the validity of the constructed scale. The results indicate that the time management scale has good reliability and validity. In Study 2, we performed a covariance structural analysis to verify our model that hypothesized that time management influences perceived control of time and psychological stress response, and perceived control of time influences psychological stress response. The results showed that time estimation increases the perceived control of time, which in turn decreases stress response. However, we also found that taking each moment as it comes reduces perceived control of time, which in turn increases stress response.

  8. Dynamical theory of responsivity and response time of a high temperature superconductor photo-thermoelectrical bolometer

    NASA Astrophysics Data System (ADS)

    Kaila, M. M.

    2002-11-01

    Dynamical theory of responsivity and response time for an high temperature superconductor (HTSC) photo-thermoelectrical bolometer is analysed in this paper. There is a thermoelectric feedback (TEF) due to the heat transfer from the sensitive area (HTSC-BiSb thermojunction) towards the cold junction of the thermocouple. This is in addition to the normal electrothermal feedback (ETF) between the detector and the substrate, in a photoelectrical bolometer. The two legs of the thermocouple are connected in a parallel geometry configuration. It is seen that TEF can be used in combination with the ETF to enhance responsivity and response time of the detector.

  9. Patient-specific instrument can achieve same accuracy with less resection time than navigation assistance in periacetabular pelvic tumor surgery: a cadaveric study.

    PubMed

    Wong, Kwok-Chuen; Sze, Kwan-Yik; Wong, Irene Oi-Ling; Wong, Chung-Ming; Kumta, Shekhar-Madhukar

    2016-02-01

    Inaccurate resection in pelvic tumors can result in compromised margins with increase local recurrence. Navigation-assisted and patient-specific instrument (PSI) techniques have recently been reported in assisting pelvic tumor surgery with the tendency of improving surgical accuracy. We examined and compared the accuracy of transferring a virtual pelvic resection plan to actual surgery using navigation-assisted or PSI technique in a cadaver study. We performed CT scan in twelve cadaveric bodies including whole pelvic bones. Either supraacetabular or partial acetabular resection was virtually planned in a hemipelvis using engineering software. The virtual resection plan was transferred to a CT-based navigation system or was used for design and fabrication of PSI. Pelvic resections were performed using navigation assistance in six cadavers and PSI in another six. Post-resection images were co-registered with preoperative planning for comparative analysis of resection accuracy in the two techniques. The mean average deviation error from the planned resection was no different ([Formula: see text]) for the navigation and the PSI groups: 1.9 versus 1.4 mm, respectively. The mean time required for the bone resection was greater ([Formula: see text]) for the navigation group than for the PSI group: 16.2 versus 1.1 min, respectively. In simulated periacetabular pelvic tumor resections, PSI technique enabled surgeons to reproduce the virtual surgical plan with similar accuracy but with less bone resection time when compared with navigation assistance. Further studies are required to investigate the clinical benefits of PSI technique in pelvic tumor surgery.

  10. 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

  11. 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.

  12. Planning multiple movements within a fixed time limit: The cost of constrained time allocation in a visuo-motor task

    PubMed Central

    Zhang, Hang; Wu, Shih-Wei; Maloney, Laurence T.

    2010-01-01

    S.-W. Wu, M. F. Dal Martello, and L. T. Maloney (2009) evaluated subjects' performance in a visuo-motor task where subjects were asked to hit two targets in sequence within a fixed time limit. Hitting targets earned rewards and Wu et al. varied rewards associated with targets. They found that subjects failed to maximize expected gain; they failed to invest more time in the movement to the more valuable target. What could explain this lack of response to reward? We first considered the possibility that subjects require training in allocating time between two movements. In Experiment 1, we found that, after extensive training, subjects still failed: They did not vary time allocation with changes in payoff. However, their actual gains equaled or exceeded the expected gain of an ideal time allocator, indicating that constraining time itself has a cost for motor accuracy. In a second experiment, we found that movements made under externally imposed time limits were less accurate than movements made with the same timing freely selected by the mover. Constrained time allocation cost about 17% in expected gain. These results suggest that there is no single speed–accuracy tradeoff for movement in our task and that subjects pursued different motor strategies with distinct speed–accuracy tradeoffs in different conditions. PMID:20884550

  13. 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.

  14. 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.

  15. Overeating at dinner time among Japanese workers: Is overeating related to stress response and late dinner times?

    PubMed

    Suzuki, Akiko; Sakurazawa, Hirofumi; Fujita, Takanori; Akamatsu, Rie

    2016-06-01

    There are several known risk factors for overeating, including negative feelings and hunger. It was hypothesized that overtime work is associated with stress responses and later dinner times, leading to longer periods of time without eating, and that this, in turn, leads to a strong experience of hunger and consequent overeating at dinner. The aim of this study was to examine relationships among overeating at dinner, stress responses (e.g., fatigue, anxiety, and depression), and dinner times in Japanese male workers. In December 2012, 255 Japanese male workers at a leasing company completed a self-report questionnaire about overeating at dinner, psychological stress responses, physical stress responses, and dinner times. Each worker was sent an email with a link to the questionnaire website, where his answers were collected. Relationships between overeating at dinner and lifestyle issues were investigated using multiple linear regression analysis treating overeating as a dependent variable. Factors related to overeating at dinner included psychological stress response (β = 0.251 p < 0.001) and dinner time (β = 0.220, p = 0.004). These cross-sectional data suggest that overeating at dinner is related to dinner time in men and to stress responses. Copyright © 2016 Elsevier Ltd. All rights reserved.

  16. A Nonparametric Approach to Estimate Classification Accuracy and Consistency

    ERIC Educational Resources Information Center

    Lathrop, Quinn N.; Cheng, Ying

    2014-01-01

    When cut scores for classifications occur on the total score scale, popular methods for estimating classification accuracy (CA) and classification consistency (CC) require assumptions about a parametric form of the test scores or about a parametric response model, such as item response theory (IRT). This article develops an approach to estimate CA…

  17. Effects of accuracy motivation and anchoring on metacomprehension judgment and accuracy.

    PubMed

    Zhao, Qin

    2012-01-01

    The current research investigates how accuracy motivation impacts anchoring and adjustment in metacomprehension judgment and how accuracy motivation and anchoring affect metacomprehension accuracy. Participants were randomly assigned to one of six conditions produced by the between-subjects factorial design involving accuracy motivation (incentive or no) and peer performance anchor (95%, 55%, or no). Two studies showed that accuracy motivation did not impact anchoring bias, but the adjustment-from-anchor process occurred. Accuracy incentive increased anchor-judgment gap for the 95% anchor but not for the 55% anchor, which induced less certainty about the direction of adjustment. The findings offer support to the integrative theory of anchoring. Additionally, the two studies revealed a "power struggle" between accuracy motivation and anchoring in influencing metacomprehension accuracy. Accuracy motivation could improve metacomprehension accuracy in spite of anchoring effect, but if anchoring effect is too strong, it could overpower the motivation effect. The implications of the findings were discussed.

  18. Time maintenance system for the BMDO MSX spacecraft

    NASA Technical Reports Server (NTRS)

    Hermes, Martin J.

    1994-01-01

    The Johns Hopkins University Applied Physics Laboratory (APL) is responsible for designing and implementing a clock maintenance system for the Ballistic Missile Defense Organizations (BMDO) Midcourse Space Experiment (MSX) spacecraft. The MSX spacecraft has an on-board clock that will be used to control execution of time-dependent commands and to time tag all science and housekeeping data received from the spacecraft. MSX mission objectives have dictated that this spacecraft time, UTC(MSX), maintain a required accuracy with respect to UTC(USNO) of +/- 10 ms with a +/- 1 ms desired accuracy. APL's atomic time standards and the downlinked spacecraft time were used to develop a time maintenance system that will estimate the current MSX clock time offset during an APL pass and make estimates of the clock's drift and aging using the offset estimates from many passes. Using this information, the clock's accuracy will be maintained by uplinking periodic clock correction commands. The resulting time maintenance system is a combination of offset measurement, command/telemetry, and mission planning hardware and computing assets. All assets provide necessary inputs for deciding when corrections to the MSX spacecraft clock must be made to maintain its required accuracy without inhibiting other mission objectives. The MSX time maintenance system is described as a whole and the clock offset measurement subsystem, a unique combination of precision time maintenance and measurement hardware controlled by a Macintosh computer, is detailed. Simulations show that the system estimates the MSX clock offset to less than+/- 33 microseconds.

  19. Systematic review and meta-analysis of the accuracy of MRI and endorectal ultrasound in the restaging and response assessment of rectal cancer following neoadjuvant therapy.

    PubMed

    Memon, S; Lynch, A C; Bressel, M; Wise, A G; Heriot, A G

    2015-09-01

    Restaging imaging by MRI or endorectal ultrasound (ERUS) following neoadjuvant chemoradiotherapy is not routinely performed, but the assessment of response is becoming increasingly important to facilitate individualization of management. A search of the MEDLINE and Scopus databases was performed for studies that evaluated the accuracy of restaging of rectal cancer following neoadjuvant chemoradiotherapy with MRI or ERUS against the histopathological outcome. A systematic review of selected studies was performed. The methodological quality of studies that qualified for meta-analysis was critically assessed to identify studies suitable for inclusion in the meta-analysis. Sixty-three articles were included in the systematic review. Twelve restaging MRI studies and 18 restaging ERUS studies were eligible for meta-analysis of T-stage restaging accuracy. Overall, ERUS T-stage restaging accuracy (mean [95% CI]: 65% [56-72%]) was nonsignificantly higher than MRI T-stage accuracy (52% [44-59%]). Restaging MRI is accurate at excluding circumferential resection margin involvement. Restaging MRI and ERUS were equivalent for prediction of nodal status: the accuracy of both investigations was 72% with over-staging and under-staging occurring in 10-15%. The heterogeneity amongst restaging studies is high, limiting conclusive findings regarding their accuracies. The accuracy of restaging imaging is different for different pathological T stages and highest for T3 tumours. Morphological assessment of T- or N-stage by MRI or ERUS is currently not accurate or consistent enough for clinical application. Restaging MRI appears to have a role in excluding circumferential resection margin involvement. Colorectal Disease © 2015 The Association of Coloproctology of Great Britain and Ireland.

  20. Separating the effects of interreinforcement time and number of interreinforcement responses1

    PubMed Central

    Neuringer, Allen J.; Schneider, Bruce A.

    1968-01-01

    The relative importance of interreinforcement time and interreinforcement responses was evaluated by varying each independently. To do this, a blackout was presented after each nonreinforced response under both fixed-ratio and fixed-interval schedules of reinforcement. Manipulating the blackout duration under the fixed-ratio schedule caused interreinforcement time to vary without affecting the number of interreinforcement responses. Pigeons' post-reinforcement and post-blackout response latencies were found to increase linearly with interreinforcement time. Under the fixed-interval schedule, the same blackout manipulations changed the number of interreinforcement responses without affecting interreinforcement time. Post-reinforcement and post-blackout response latencies under this condition were approximately constant. These results suggest that responding is controlled by interreinforcement time and is not influenced by the number of responses emitted between reinforcements. PMID:16811313

  1. 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.

  2. It Matters Whether Reading Comprehension Is Conceptualised as Rate or Accuracy

    ERIC Educational Resources Information Center

    Rønberg, Louise Flensted; Petersen, Dorthe Klint

    2016-01-01

    This study shows that it makes a difference whether accuracy measures or rate measures are used when assessing reading comprehension. When the outcome is reading comprehension accuracy (i.e., the number of correct responses), word reading skills (measured as access to orthographic representations) account for a modest amount of the variance in the…

  3. Dynamic Sensorimotor Planning during Long-Term Sequence Learning: The Role of Variability, Response Chunking and Planning Errors

    PubMed Central

    Verstynen, Timothy; Phillips, Jeff; Braun, Emily; Workman, Brett; Schunn, Christian; Schneider, Walter

    2012-01-01

    Many everyday skills are learned by binding otherwise independent actions into a unified sequence of responses across days or weeks of practice. Here we looked at how the dynamics of action planning and response binding change across such long timescales. Subjects (N = 23) were trained on a bimanual version of the serial reaction time task (32-item sequence) for two weeks (10 days total). Response times and accuracy both showed improvement with time, but appeared to be learned at different rates. Changes in response speed across training were associated with dynamic changes in response time variability, with faster learners expanding their variability during the early training days and then contracting response variability late in training. Using a novel measure of response chunking, we found that individual responses became temporally correlated across trials and asymptoted to set sizes of approximately 7 bound responses at the end of the first week of training. Finally, we used a state-space model of the response planning process to look at how predictive (i.e., response anticipation) and error-corrective (i.e., post-error slowing) processes correlated with learning rates for speed, accuracy and chunking. This analysis yielded non-monotonic association patterns between the state-space model parameters and learning rates, suggesting that different parts of the response planning process are relevant at different stages of long-term learning. These findings highlight the dynamic modulation of response speed, variability, accuracy and chunking as multiple movements become bound together into a larger set of responses during sequence learning. PMID:23056630

  4. Analysis and improvements of Adaptive Particle Refinement (APR) through CPU time, accuracy and robustness considerations

    NASA Astrophysics Data System (ADS)

    Chiron, L.; Oger, G.; de Leffe, M.; Le Touzé, D.

    2018-02-01

    While smoothed-particle hydrodynamics (SPH) simulations are usually performed using uniform particle distributions, local particle refinement techniques have been developed to concentrate fine spatial resolutions in identified areas of interest. Although the formalism of this method is relatively easy to implement, its robustness at coarse/fine interfaces can be problematic. Analysis performed in [16] shows that the radius of refined particles should be greater than half the radius of unrefined particles to ensure robustness. In this article, the basics of an Adaptive Particle Refinement (APR) technique, inspired by AMR in mesh-based methods, are presented. This approach ensures robustness with alleviated constraints. Simulations applying the new formalism proposed achieve accuracy comparable to fully refined spatial resolutions, together with robustness, low CPU times and maintained parallel efficiency.

  5. 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.

  6. Enhancing the accuracy of subcutaneous glucose sensors: a real-time deconvolution-based approach.

    PubMed

    Guerra, Stefania; Facchinetti, Andrea; Sparacino, Giovanni; Nicolao, Giuseppe De; Cobelli, Claudio

    2012-06-01

    Minimally invasive continuous glucose monitoring (CGM) sensors can greatly help diabetes management. Most of these sensors consist of a needle electrode, placed in the subcutaneous tissue, which measures an electrical current exploiting the glucose-oxidase principle. This current is then transformed to glucose levels after calibrating the sensor on the basis of one, or more, self-monitoring blood glucose (SMBG) samples. In this study, we design and test a real-time signal-enhancement module that, cascaded to the CGM device, improves the quality of its output by a proper postprocessing of the CGM signal. In fact, CGM sensors measure glucose in the interstitium rather than in the blood compartment. We show that this distortion can be compensated by means of a regularized deconvolution procedure relying on a linear regression model that can be updated whenever a pair of suitably sampled SMBG references is collected. Tests performed both on simulated and real data demonstrate a significant accuracy improvement of the CGM signal. Simulation studies also demonstrate the robustness of the method against departures from nominal conditions, such as temporal misplacement of the SMBG samples and uncertainty in the blood-to-interstitium glucose kinetic model. Thanks to its online capabilities, the proposed signal-enhancement algorithm can be used to improve the performance of CGM-based real-time systems such as the hypo/hyper glycemic alert generators or the artificial pancreas.

  7. Motherhood and drug-dependency: the attributes of full-time versus part-time responsibility for child care.

    PubMed

    Jackson, M R; Berry, G L

    1994-10-01

    This study examined differences between the maternal characteristics of African-American drug-dependent mothers who have full-time responsibility for child care and those having part-time responsibility. The study revealed that full-time mothers have significantly higher levels of maternal adaptation than part-time mothers. For part-time mothers, the level of maternal adaptation or self-esteem did not fluctuate, regardless of whether she saw the child 4 days a week or once a month. The article identifies variables that may facilitate better maternal behaviors among drug-dependent mothers.

  8. 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

  9. 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

    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.

  10. The Role of Teacher's Corrective Feedback in Improving Iranian EFL Learners' Writing Accuracy over Time: Is Learner's Mother Tongue Relevant?

    ERIC Educational Resources Information Center

    Rahimi, Mohammad

    2009-01-01

    The purpose of the present study was to investigate the impact of feedback on writing accuracy over time and examine the relevance of the students' mother tongue to the feedback effect. To this end, the study compared two groups of Iranian English majors (N = 56) over a period of four months: one with indirect grammar feedback and the other with…

  11. Accuracy of a real-time surgical navigation system for the placement of quad zygomatic implants in the severe atrophic maxilla: A pilot clinical study.

    PubMed

    Hung, Kuo-Feng; Wang, Feng; Wang, Hao-Wei; Zhou, Wen-Jie; Huang, Wei; Wu, Yi-Qun

    2017-06-01

    A real-time surgical navigation system potentially increases the accuracy when used for quad-zygomatic implant placement. To evaluate the accuracy of a real-time surgical navigation system when used for quad zygomatic implant placement. Patients with severely atrophic maxillae were prospectively recruited. Four trajectories for implants were planned, and zygomatic implants were placed using a real-time surgical navigation system. The planned-placed distance deviations at entry (entry deviation)points, exit (exit deviation) points, and angle deviation of axes (angle deviation) were measured on fused operation images. The differences of all the deviations between different groups, classified based on the lengths and locations of implants, were analysed. A P value of < 0.05 indicated statistical significance. Forty zygomatic implants were placed as planned in 10 patients. The entry deviation, exit deviation and angle deviation were 1.35 ± 0.75 mm, 2.15 mm ± 0.95 mm, and 2.05 ± 1.02 degrees, respectively. The differences of all deviations were not significant, irrespective of the lengths (P = .259, .158, and .914, respectively) or locations of the placed implants (P = .698, .072, and .602, respectively). A real-time surgical navigation system used for the placement of quad zygomatic implants demonstrated a high level of accuracy with only minimal planned-placed deviations, irrespective of the lengths or locations of the implants. © 2017 Wiley Periodicals, Inc.

  12. 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.

  13. 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.

  14. Metacognitive Influences on Study Time Allocation in an Associative Recognition Task: An Analysis of Adult Age Differences

    PubMed Central

    Hines, Jarrod C.; Touron, Dayna R.; Hertzog, Christopher

    2009-01-01

    The current study evaluated a metacognitive account of study time allocation, which argues that metacognitive monitoring of recognition test accuracy and latency influences subsequent strategic control and regulation. We examined judgments of learning (JOLs), recognition test confidence judgments (CJs), and subjective response time (RT) judgments by younger and older adults in an associative recognition task involving two study-test phases, with self-paced study in phase 2. Multilevel regression analyses assessed the degree to which age and metacognitive variables predicted phase 2 study time independent of actual test accuracy and RT. Outcomes supported the metacognitive account – JOLs and CJs predicted study time independent of recognition accuracy. For older adults with errant RT judgments, subjective retrieval fluency influenced response confidence as well as (mediated through confidence) subsequent study time allocation. Older adults studied items longer which had been assigned lower CJs, suggesting no age deficit in using memory monitoring to control learning. PMID:19485662

  15. Accuracy of a new real-time continuous glucose monitoring algorithm.

    PubMed

    Keenan, D Barry; Cartaya, Raymond; Mastrototaro, John J

    2010-01-01

    Through minimally invasive sensor-based continuous glucose monitoring (CGM), individuals can manage their blood glucose (BG) levels more aggressively, thereby improving their hemoglobin A1c level, while reducing the risk of hypoglycemia. Tighter glycemic control through CGM, however, requires an accurate glucose sensor and calibration algorithm with increased performance at lower BG levels. Sensor and BG measurements for 72 adult and adolescent subjects were obtained during the course of a 26-week multicenter study evaluating the efficacy of the Paradigm REAL-Time (PRT) sensor-augmented pump system (Medtronic Diabetes, Northridge, CA) in an outpatient setting. Subjects in the study arm performed at least four daily finger stick measurements. A retrospective analysis of the data set was performed to evaluate a new calibration algorithm utilized in the Paradigm Veo insulin pump (Medtronic Diabetes) and to compare these results to performance metrics calculated for the PRT. A total of N = 7193 PRT sensor downloads for 3 days of use, as well as 90,472 temporally and nonuniformly paired data points (sensor and meter values), were evaluated, with 5841 hypoglycemic and 15,851 hyperglycemic events detected through finger stick measurements. The Veo calibration algorithm decreased the overall mean absolute relative difference by greater than 0.25 to 15.89%, with hypoglycemia sensitivity increased from 54.9% in the PRT to 82.3% in the Veo (90.5% with predictive alerts); however, hyperglycemia sensitivity was decreased only marginally from 86% in the PRT to 81.7% in the Veo. The Veo calibration algorithm, with sensor error reduced significantly in the 40- to 120-mg/dl range, improves hypoglycemia detection, while retaining accuracy at high glucose levels. 2010 Diabetes Technology Society.

  16. 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.…

  17. Time-gated scintillator imaging for real-time optical surface dosimetry in total skin electron therapy.

    PubMed

    Bruza, Petr; Gollub, Sarah L; Andreozzi, Jacqueline M; Tendler, Irwin I; Williams, Benjamin B; Jarvis, Lesley A; Gladstone, David J; Pogue, Brian W

    2018-05-02

    The purpose of this study was to measure surface dose by remote time-gated imaging of plastic scintillators. A novel technique for time-gated, intensified camera imaging of scintillator emission was demonstrated, and key parameters influencing the signal were analyzed, including distance, angle and thickness. A set of scintillator samples was calibrated by using thermo-luminescence detector response as reference. Examples of use in total skin electron therapy are described. The data showed excellent room light rejection (signal-to-noise ratio of scintillation SNR  ≈  470), ideal scintillation dose response linearity, and 2% dose rate error. Individual sample scintillation response varied by 7% due to sample preparation. Inverse square distance dependence correction and lens throughput error (8% per meter) correction were needed. At scintillator-to-source angle and observation angle  <50°, the radiant energy fluence error was smaller than 1%. The achieved standard error of the scintillator cumulative dose measurement compared to the TLD dose was 5%. The results from this proof-of-concept study documented the first use of small scintillator targets for remote surface dosimetry in ambient room lighting. The measured dose accuracy renders our method to be comparable to thermo-luminescent detector dosimetry, with the ultimate realization of accuracy likely to be better than shown here. Once optimized, this approach to remote dosimetry may substantially reduce the time and effort required for surface dosimetry.

  18. Time-gated scintillator imaging for real-time optical surface dosimetry in total skin electron therapy

    NASA Astrophysics Data System (ADS)

    Bruza, Petr; Gollub, Sarah L.; Andreozzi, Jacqueline M.; Tendler, Irwin I.; Williams, Benjamin B.; Jarvis, Lesley A.; Gladstone, David J.; Pogue, Brian W.

    2018-05-01

    The purpose of this study was to measure surface dose by remote time-gated imaging of plastic scintillators. A novel technique for time-gated, intensified camera imaging of scintillator emission was demonstrated, and key parameters influencing the signal were analyzed, including distance, angle and thickness. A set of scintillator samples was calibrated by using thermo-luminescence detector response as reference. Examples of use in total skin electron therapy are described. The data showed excellent room light rejection (signal-to-noise ratio of scintillation SNR  ≈  470), ideal scintillation dose response linearity, and 2% dose rate error. Individual sample scintillation response varied by 7% due to sample preparation. Inverse square distance dependence correction and lens throughput error (8% per meter) correction were needed. At scintillator-to-source angle and observation angle  <50°, the radiant energy fluence error was smaller than 1%. The achieved standard error of the scintillator cumulative dose measurement compared to the TLD dose was 5%. The results from this proof-of-concept study documented the first use of small scintillator targets for remote surface dosimetry in ambient room lighting. The measured dose accuracy renders our method to be comparable to thermo-luminescent detector dosimetry, with the ultimate realization of accuracy likely to be better than shown here. Once optimized, this approach to remote dosimetry may substantially reduce the time and effort required for surface dosimetry.

  19. Factoring vs linear modeling in rate estimation: a simulation study of relative accuracy.

    PubMed

    Maldonado, G; Greenland, S

    1998-07-01

    A common strategy for modeling dose-response in epidemiology is to transform ordered exposures and covariates into sets of dichotomous indicator variables (that is, to factor the variables). Factoring tends to increase estimation variance, but it also tends to decrease bias and thus may increase or decrease total accuracy. We conducted a simulation study to examine the impact of factoring on the accuracy of rate estimation. Factored and unfactored Poisson regression models were fit to follow-up study datasets that were randomly generated from 37,500 population model forms that ranged from subadditive to supramultiplicative. In the situations we examined, factoring sometimes substantially improved accuracy relative to fitting the corresponding unfactored model, sometimes substantially decreased accuracy, and sometimes made little difference. The difference in accuracy between factored and unfactored models depended in a complicated fashion on the difference between the true and fitted model forms, the strength of exposure and covariate effects in the population, and the study size. It may be difficult in practice to predict when factoring is increasing or decreasing accuracy. We recommend, therefore, that the strategy of factoring variables be supplemented with other strategies for modeling dose-response.

  20. Excited-state absorption in tetrapyridyl porphyrins: comparing real-time and quadratic-response time-dependent density functional theory

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Bowman, David N.; Asher, Jason C.; Fischer, Sean A.

    2017-01-01

    Threemeso-substituted tetrapyridyl porphyrins (free base, Ni(ii), and Cu(ii)) were investigated for their optical limiting (OL) capabilities using real-time (RT-), linear-response (LR-), and quadratic-response (QR-) time-dependent density functional theory (TDDFT) methods.

  1. Increasing the efficiency and accuracy of time-resolved electronic spectra calculations with on-the-fly ab initio quantum dynamics methods

    NASA Astrophysics Data System (ADS)

    Vanicek, Jiri

    2014-03-01

    Rigorous quantum-mechanical calculations of coherent ultrafast electronic spectra remain difficult. I will present several approaches developed in our group that increase the efficiency and accuracy of such calculations: First, we justified the feasibility of evaluating time-resolved spectra of large systems by proving that the number of trajectories needed for convergence of the semiclassical dephasing representation/phase averaging is independent of dimensionality. Recently, we further accelerated this approximation with a cellular scheme employing inverse Weierstrass transform and optimal scaling of the cell size. The accuracy of potential energy surfaces was increased by combining the dephasing representation with accurate on-the-fly ab initio electronic structure calculations, including nonadiabatic and spin-orbit couplings. Finally, the inherent semiclassical approximation was removed in the exact quantum Gaussian dephasing representation, in which semiclassical trajectories are replaced by communicating frozen Gaussian basis functions evolving classically with an average Hamiltonian. Among other examples I will present an on-the-fly ab initio semiclassical dynamics calculation of the dispersed time-resolved stimulated emission spectrum of the 54-dimensional azulene. This research was supported by EPFL and by the Swiss National Science Foundation NCCR MUST (Molecular Ultrafast Science and Technology) and Grant No. 200021124936/1.

  2. Cued Speech Transliteration: Effects of Accuracy and Lag Time on Message Intelligibility

    ERIC Educational Resources Information Center

    Krause, Jean C.; Lopez, Katherine A.

    2017-01-01

    This paper is the second in a series concerned with the level of access afforded to students who use educational interpreters. The first paper (Krause & Tessler, 2016) focused on factors affecting accuracy of messages produced by Cued Speech (CS) transliterators (expression). In this study, factors affecting intelligibility (reception by deaf…

  3. Sound source localization identification accuracy: Envelope dependencies.

    PubMed

    Yost, William A

    2017-07-01

    Sound source localization accuracy as measured in an identification procedure in a front azimuth sound field was studied for click trains, modulated noises, and a modulated tonal carrier. Sound source localization accuracy was determined as a function of the number of clicks in a 64 Hz click train and click rate for a 500 ms duration click train. The clicks were either broadband or high-pass filtered. Sound source localization accuracy was also measured for a single broadband filtered click and compared to a similar broadband filtered, short-duration noise. Sound source localization accuracy was determined as a function of sinusoidal amplitude modulation and the "transposed" process of modulation of filtered noises and a 4 kHz tone. Different rates (16 to 512 Hz) of modulation (including unmodulated conditions) were used. Providing modulation for filtered click stimuli, filtered noises, and the 4 kHz tone had, at most, a very small effect on sound source localization accuracy. These data suggest that amplitude modulation, while providing information about interaural time differences in headphone studies, does not have much influence on sound source localization accuracy in a sound field.

  4. Accuracy of Monte Carlo photon transport simulation in characterizing brachytherapy dosimeter energy-response artefacts

    NASA Astrophysics Data System (ADS)

    Das, R. K.; Li, Z.; Perera, H.; Williamson, J. F.

    1996-06-01

    Practical dosimeters in brachytherapy, such as thermoluminescent dosimeters (TLD) and diodes, are usually calibrated against low-energy megavoltage beams. To measure absolute dose rate near a brachytherapy source, it is necessary to establish the energy response of the detector relative to that of the calibration energy. The purpose of this paper is to assess the accuracy of Monte Carlo photon transport (MCPT) simulation in modelling the absolute detector response as a function of detector geometry and photon energy. We have exposed two different sizes of TLD-100 (LiF chips) and p-type silicon diode detectors to calibrated , HDR source and superficial x-ray beams. For the Scanditronix electron-field diode, the relative detector response, defined as the measured detector readings per measured unit of air kerma, varied from (40 kVp beam) to ( beam). Similarly for the large and small chips the same quantity varied from and , respectively. Monte Carlo simulation was used to calculate the absorbed dose to the active volume of the detector per unit air kerma. If the Monte Carlo simulation is accurate, then the absolute detector response, which is defined as the measured detector reading per unit dose absorbed by the active detector volume, and is calculated by Monte Carlo simulation, should be a constant. For the diode, the absolute response is . For TLDs of size

  5. Accuracy of a vertical jump contact mat for determining jump height and flight time.

    PubMed

    Whitmer, Tyler D; Fry, Andrew C; Forsythe, Charles M; Andre, Matthew J; Lane, Michael T; Hudy, Andrea; Honnold, Darric E

    2015-04-01

    Several devices are available to measure vertical jump (VJ) height based on flight time, VJ reach height, or ground reaction forces. The purpose of this study was to determine the accuracy of a VJ mat for measuring flight time and VJ height compared with a VJ tester or a force plate. Seventeen men and 18 women (X ± SD; age = 20.9 ± 0.7 years, height = 176.1 ± 0.9 cm, weight = 72.6 ± 13.5 kg) served as subjects. Subjects performed counter-movement vertical jumps while standing on both a force plate (1,000 Hz) and a VJ mat. A Vertec VJ tester was used to measure jump reach. Compared with the force plate, the VJ mat reported greater VJ height (VJ mat = 0.50 ± 0.12 m, force plate = 0.34 ± 0.10 m) and flight time (VJ mat = 0.629 ± 0.078 seconds, force plate = 0.524 ± 0.077 seconds). Comparison of VJ heights from the VJ mat and the Vertec revealed no significant differences (Vertec = 0.48 ± 0.11 m). Regression analyses indicated strong relationships between testing methods and suggested that high VJ performances may be underestimated with the VJ mat. This particular VJ mat compared favorably with the Vertec but not the force plate. It seems that the different flight times derived from the VJ mat may permit the VJ mat to be in closer agreement with VJ heights from the Vertec. Also, the VJ mat may not be an appropriate tool for assessing high VJ performances (i.e., ≥0.70 m; ≈28 inches). Practitioners and researchers using similar VJ mats may not obtain accurate flight times and may underestimate high performers.

  6. Recognition memory and awareness: A high-frequency advantage in the accuracy of knowing.

    PubMed

    Gregg, Vernon H; Gardiner, John M; Karayianni, Irene; Konstantinou, Ira

    2006-04-01

    The well-established advantage of low-frequency words over high-frequency words in recognition memory has been found to occur in remembering and not knowing. Two experiments employed remember and know judgements, and divided attention to investigate the possibility of an effect of word frequency on know responses given appropriate study conditions. With undivided attention at study, the usual low-frequency advantage in the accuracy of remember responses, but no effect on know responses, was obtained. Under a demanding divided attention task at encoding, a high-frequency advantage in the accuracy of know responses was obtained. The results are discussed in relation to theories of knowing, particularly those incorporating perceptual and conceptual fluency.

  7. Effect of time discretization of the imaging process on the accuracy of trajectory estimation in fluorescence microscopy

    PubMed Central

    Wong, Yau; Chao, Jerry; Lin, Zhiping; Ober, Raimund J.

    2014-01-01

    In fluorescence microscopy, high-speed imaging is often necessary for the proper visualization and analysis of fast subcellular dynamics. Here, we examine how the speed of image acquisition affects the accuracy with which parameters such as the starting position and speed of a microscopic non-stationary fluorescent object can be estimated from the resulting image sequence. Specifically, we use a Fisher information-based performance bound to investigate the detector-dependent effect of frame rate on the accuracy of parameter estimation. We demonstrate that when a charge-coupled device detector is used, the estimation accuracy deteriorates as the frame rate increases beyond a point where the detector’s readout noise begins to overwhelm the low number of photons detected in each frame. In contrast, we show that when an electron-multiplying charge-coupled device (EMCCD) detector is used, the estimation accuracy improves with increasing frame rate. In fact, at high frame rates where the low number of photons detected in each frame renders the fluorescent object difficult to detect visually, imaging with an EMCCD detector represents a natural implementation of the Ultrahigh Accuracy Imaging Modality, and enables estimation with an accuracy approaching that which is attainable only when a hypothetical noiseless detector is used. PMID:25321248

  8. Simulating transient dynamics of the time-dependent time fractional Fokker-Planck systems

    NASA Astrophysics Data System (ADS)

    Kang, Yan-Mei

    2016-09-01

    For a physically realistic type of time-dependent time fractional Fokker-Planck (FP) equation, derived as the continuous limit of the continuous time random walk with time-modulated Boltzmann jumping weight, a semi-analytic iteration scheme based on the truncated (generalized) Fourier series is presented to simulate the resultant transient dynamics when the external time modulation is a piece-wise constant signal. At first, the iteration scheme is demonstrated with a simple time-dependent time fractional FP equation on finite interval with two absorbing boundaries, and then it is generalized to the more general time-dependent Smoluchowski-type time fractional Fokker-Planck equation. The numerical examples verify the efficiency and accuracy of the iteration method, and some novel dynamical phenomena including polarized motion orientations and periodic response death are discussed.

  9. 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.

  10. 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

  11. 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.

  12. 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

  13. Psychology Textbooks: Examining Their Accuracy

    ERIC Educational Resources Information Center

    Steuer, Faye B.; Ham, K. Whitfield, II

    2008-01-01

    Sales figures and recollections of psychologists indicate textbooks play a central role in psychology students' education, yet instructors typically must select texts under time pressure and with incomplete information. Although selection aids are available, none adequately address the accuracy of texts. We describe a technique for sampling…

  14. Effect of time of day on the vertical spinal creep response.

    PubMed

    Puntumetakul, Rungthip; Trott, Patricia; Williams, Marie; Fulton, Ian

    2009-01-01

    Vertical spinal creep (VSC) is height loss during sustained postures over a set period of time. While total stature has been demonstrated to decrease throughout the day, whether a diurnal effect applies to the VSC response has not been reported. The aim of this study was to investigate whether time of day had an effect on the magnitude of the VSC response in young subjects asymptomatic for musculoskeletal pathologies. The VSC response was recorded over 25 min while subjects remained seated on the stadiometer, at three times (morning, midday and afternoon) on the same day, in 48 asymptomatic volunteers aged 20-39 years. While no significant differences were calculated for the magnitude of the VSC responses on the three occasions of testing, differences in magnitude of VSC response may have been confounded by preloading activities. Where magnitude of the VSC response is the primary outcome measure, measurement protocols should control preloading activities and continue to conduct measurements at the same time of day, until further studies conclusively refute the existence of a diurnal effect.

  15. 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.

  16. a New Approach for Accuracy Improvement of Pulsed LIDAR Remote Sensing Data

    NASA Astrophysics Data System (ADS)

    Zhou, G.; Huang, W.; Zhou, X.; He, C.; Li, X.; Huang, Y.; Zhang, L.

    2018-05-01

    In remote sensing applications, the accuracy of time interval measurement is one of the most important parameters that affect the quality of pulsed lidar data. The traditional time interval measurement technique has the disadvantages of low measurement accuracy, complicated circuit structure and large error. A high-precision time interval data cannot be obtained in these traditional methods. In order to obtain higher quality of remote sensing cloud images based on the time interval measurement, a higher accuracy time interval measurement method is proposed. The method is based on charging the capacitance and sampling the change of capacitor voltage at the same time. Firstly, the approximate model of the capacitance voltage curve in the time of flight of pulse is fitted based on the sampled data. Then, the whole charging time is obtained with the fitting function. In this method, only a high-speed A/D sampler and capacitor are required in a single receiving channel, and the collected data is processed directly in the main control unit. The experimental results show that the proposed method can get error less than 3 ps. Compared with other methods, the proposed method improves the time interval accuracy by at least 20 %.

  17. Thematic and positional accuracy assessment of digital remotely sensed data

    Treesearch

    Russell G. Congalton

    2007-01-01

    Accuracy assessment or validation has become a standard component of any land cover or vegetation map derived from remotely sensed data. Knowing the accuracy of the map is vital to any decisionmaking performed using that map. The process of assessing the map accuracy is time consuming and expensive. It is very important that the procedure be well thought out and...

  18. Real-time detection and discrimination of visual perception using electrocorticographic signals

    NASA Astrophysics Data System (ADS)

    Kapeller, C.; Ogawa, H.; Schalk, G.; Kunii, N.; Coon, W. G.; Scharinger, J.; Guger, C.; Kamada, K.

    2018-06-01

    Objective. Several neuroimaging studies have demonstrated that the ventral temporal cortex contains specialized regions that process visual stimuli. This study investigated the spatial and temporal dynamics of electrocorticographic (ECoG) responses to different types and colors of visual stimulation that were presented to four human participants, and demonstrated a real-time decoder that detects and discriminates responses to untrained natural images. Approach. ECoG signals from the participants were recorded while they were shown colored and greyscale versions of seven types of visual stimuli (images of faces, objects, bodies, line drawings, digits, and kanji and hiragana characters), resulting in 14 classes for discrimination (experiment I). Additionally, a real-time system asynchronously classified ECoG responses to faces, kanji and black screens presented via a monitor (experiment II), or to natural scenes (i.e. the face of an experimenter, natural images of faces and kanji, and a mirror) (experiment III). Outcome measures in all experiments included the discrimination performance across types based on broadband γ activity. Main results. Experiment I demonstrated an offline classification accuracy of 72.9% when discriminating among the seven types (without color separation). Further discrimination of grey versus colored images reached an accuracy of 67.1%. Discriminating all colors and types (14 classes) yielded an accuracy of 52.1%. In experiment II and III, the real-time decoder correctly detected 73.7% responses to face, kanji and black computer stimuli and 74.8% responses to presented natural scenes. Significance. Seven different types and their color information (either grey or color) could be detected and discriminated using broadband γ activity. Discrimination performance maximized for combined spatial-temporal information. The discrimination of stimulus color information provided the first ECoG-based evidence for color-related population

  19. Orbit Determination Accuracy for Comets on Earth-Impacting Trajectories

    NASA Technical Reports Server (NTRS)

    Kay-Bunnell, Linda

    2004-01-01

    The results presented show the level of orbit determination accuracy obtainable for long-period comets discovered approximately one year before collision with Earth. Preliminary orbits are determined from simulated observations using Gauss' method. Additional measurements are incorporated to improve the solution through the use of a Kalman filter, and include non-gravitational perturbations due to outgassing. Comparisons between observatories in several different circular heliocentric orbits show that observatories in orbits with radii less than 1 AU result in increased orbit determination accuracy for short tracking durations due to increased parallax per unit time. However, an observatory at 1 AU will perform similarly if the tracking duration is increased, and accuracy is significantly improved if additional observatories are positioned at the Sun-Earth Lagrange points L3, L4, or L5. A single observatory at 1 AU capable of both optical and range measurements yields the highest orbit determination accuracy in the shortest amount of time when compared to other systems of observatories.

  20. Real time shear wave elastography in chronic liver diseases: Accuracy for predicting liver fibrosis, in comparison with serum markers

    PubMed Central

    Jeong, Jae Yoon; Kim, Tae Yeob; Sohn, Joo Hyun; Kim, Yongsoo; Jeong, Woo Kyoung; Oh, Young-Ha; Yoo, Kyo-Sang

    2014-01-01

    AIM: To evaluate the correlation between liver stiffness measurement (LSM) by real-time shear wave elastography (SWE) and liver fibrosis stage and the accuracy of LSM for predicting significant and advanced fibrosis, in comparison with serum markers. METHODS: We consecutively analyzed 70 patients with various chronic liver diseases. Liver fibrosis was staged from F0 to F4 according to the Batts and Ludwig scoring system. Significant and advanced fibrosis was defined as stage F ≥ 2 and F ≥ 3, respectively. The accuracy of prediction for fibrosis was analyzed using receiver operating characteristic curves. RESULTS: Seventy patients, 15 were belonged to F0-F1 stage, 20 F2, 13 F3 and 22 F4. LSM was increased with progression of fibrosis stage (F0-F1: 6.77 ± 1.72, F2: 9.98 ± 3.99, F3: 15.80 ± 7.73, and F4: 22.09 ± 10.09, P < 0.001). Diagnostic accuracies of LSM for prediction of F ≥ 2 and F ≥ 3 were 0.915 (95%CI: 0.824-0.968, P < 0.001) and 0.913 (95%CI: 0.821-0.967, P < 0.001), respectively. The cut-off values of LSM for prediction of F ≥ 2 and F ≥ 3 were 8.6 kPa with 78.2% sensitivity and 93.3% specificity and 10.46 kPa with 88.6% sensitivity and 80.0% specificity, respectively. However, there were no significant differences between LSM and serum hyaluronic acid and type IV collagen in diagnostic accuracy. CONCLUSION: SWE showed a significant correlation with the severity of liver fibrosis and was useful and accurate to predict significant and advanced fibrosis, comparable with serum markers. PMID:25320528

  1. Real time shear wave elastography in chronic liver diseases: accuracy for predicting liver fibrosis, in comparison with serum markers.

    PubMed

    Jeong, Jae Yoon; Kim, Tae Yeob; Sohn, Joo Hyun; Kim, Yongsoo; Jeong, Woo Kyoung; Oh, Young-Ha; Yoo, Kyo-Sang

    2014-10-14

    To evaluate the correlation between liver stiffness measurement (LSM) by real-time shear wave elastography (SWE) and liver fibrosis stage and the accuracy of LSM for predicting significant and advanced fibrosis, in comparison with serum markers. We consecutively analyzed 70 patients with various chronic liver diseases. Liver fibrosis was staged from F0 to F4 according to the Batts and Ludwig scoring system. Significant and advanced fibrosis was defined as stage F ≥ 2 and F ≥ 3, respectively. The accuracy of prediction for fibrosis was analyzed using receiver operating characteristic curves. Seventy patients, 15 were belonged to F0-F1 stage, 20 F2, 13 F3 and 22 F4. LSM was increased with progression of fibrosis stage (F0-F1: 6.77 ± 1.72, F2: 9.98 ± 3.99, F3: 15.80 ± 7.73, and F4: 22.09 ± 10.09, P < 0.001). Diagnostic accuracies of LSM for prediction of F ≥ 2 and F ≥ 3 were 0.915 (95%CI: 0.824-0.968, P < 0.001) and 0.913 (95%CI: 0.821-0.967, P < 0.001), respectively. The cut-off values of LSM for prediction of F ≥ 2 and F ≥ 3 were 8.6 kPa with 78.2% sensitivity and 93.3% specificity and 10.46 kPa with 88.6% sensitivity and 80.0% specificity, respectively. However, there were no significant differences between LSM and serum hyaluronic acid and type IV collagen in diagnostic accuracy. SWE showed a significant correlation with the severity of liver fibrosis and was useful and accurate to predict significant and advanced fibrosis, comparable with serum markers.

  2. Influence of time point of calibration on accuracy of continuous glucose monitoring in individuals with type 1 diabetes.

    PubMed

    Zueger, Thomas; Diem, Peter; Mougiakakou, Stavroula; Stettler, Christoph

    2012-07-01

    Data on the influence of calibration on accuracy of continuous glucose monitoring (CGM) are scarce. The aim of the present study was to investigate whether the time point of calibration has an influence on sensor accuracy and whether this effect differs according to glycemic level. Two CGM sensors were inserted simultaneously in the abdomen on either side of 20 individuals with type 1 diabetes. One sensor was calibrated predominantly using preprandial glucose (calibration(PRE)). The other sensor was calibrated predominantly using postprandial glucose (calibration(POST)). At minimum three additional glucose values per day were obtained for analysis of accuracy. Sensor readings were divided into four categories according to the glycemic range of the reference values (low, ≤4 mmol/L; euglycemic, 4.1-7 mmol/L; hyperglycemic I, 7.1-14 mmol/L; and hyperglycemic II, >14 mmol/L). The overall mean±SEM absolute relative difference (MARD) between capillary reference values and sensor readings was 18.3±0.8% for calibration(PRE) and 21.9±1.2% for calibration(POST) (P<0.001). MARD according to glycemic range was 47.4±6.5% (low), 17.4±1.3% (euglycemic), 15.0±0.8% (hyperglycemic I), and 17.7±1.9% (hyperglycemic II) for calibration(PRE) and 67.5±9.5% (low), 24.2±1.8% (euglycemic), 15.5±0.9% (hyperglycemic I), and 15.3±1.9% (hyperglycemic II) for calibration(POST). In the low and euglycemic ranges MARD was significantly lower in calibration(PRE) compared with calibration(POST) (P=0.007 and P<0.001, respectively). Sensor calibration predominantly based on preprandial glucose resulted in a significantly higher overall sensor accuracy compared with a predominantly postprandial calibration. The difference was most pronounced in the hypo- and euglycemic reference range, whereas both calibration patterns were comparable in the hyperglycemic range.

  3. Children with autism spectrum disorders show abnormal conditioned response timing on delay, but not trace, eyeblink conditioning

    PubMed Central

    Oristaglio, Jeff; West, Susan Hyman; Ghaffari, Manely; Lech, Melissa S.; Verma, Beeta R.; Harvey, John A.; Welsh, John P.; Malone, Richard P.

    2013-01-01

    Children with autism spectrum disorder (ASD) and age-matched typically-developing (TD) peers were tested on two forms of eyeblink conditioning (EBC), a Pavlovian associative learning paradigm where subjects learn to execute an appropriately-timed eyeblink in response to a previously neutral conditioning stimulus (CS). One version of the task, trace EBC, interposes a stimulus-free interval between the presentation of the CS and the unconditioned stimulus (US), a puff of air to the eye which causes subjects to blink. In delay EBC, the CS overlaps in time with the delivery of the US, usually with both stimuli terminating simultaneously. ASD children performed normally during trace EBC, exhibiting no differences from typically-developing (TD) subjects with regard to learning rate or the timing of the CR. However, when subsequently tested on delay EBC, subjects with ASD displayed abnormally-timed conditioned eye blinks that began earlier and peaked sooner than those of TD subjects, consistent with previous findings. The results suggest an impaired ability of children with ASD to properly time conditioned eye blinks which appears to be specific to delay EBC. We suggest that this deficit may reflect a dysfunction of cerebellar cortex in which increases in the intensity or duration of sensory input can temporarily disrupt the accuracy of motor timing over short temporal intervals. PMID:23769889

  4. 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…

  5. Attention Measures of Accuracy, Variability, and Fatigue Detect Early Response to Donepezil in Alzheimer's Disease: A Randomized, Double-blind, Placebo-Controlled Pilot Trial.

    PubMed

    Vila-Castelar, Clara; Ly, Jenny J; Kaplan, Lillian; Van Dyk, Kathleen; Berger, Jeffrey T; Macina, Lucy O; Stewart, Jennifer L; Foldi, Nancy S

    2018-04-09

    Donepezil is widely used to treat Alzheimer's disease (AD), but detecting early response remains challenging for clinicians. Acetylcholine is known to directly modulate attention, particularly under high cognitive conditions, but no studies to date test whether measures of attention under high load can detect early effects of donepezil. We hypothesized that load-dependent attention tasks are sensitive to short-term treatment effects of donepezil, while global and other domain-specific cognitive measures are not. This longitudinal, randomized, double-blind, placebo-controlled pilot trial (ClinicalTrials.gov Identifier: NCT03073876) evaluated 23 participants newly diagnosed with AD initiating de novo donepezil treatment (5 mg). After baseline assessment, participants were randomized into Drug (n = 12) or Placebo (n = 11) groups, and retested after approximately 6 weeks. Cognitive assessment included: (a) attention tasks (Foreperiod Effect, Attentional Blink, and Covert Orienting tasks) measuring processing speed, top-down accuracy, orienting, intra-individual variability, and fatigue; (b) global measures (Alzheimer's Disease Assessment Scale-Cognitive Subscale, Mini-Mental Status Examination, Dementia Rating Scale); and (c) domain-specific measures (memory, language, visuospatial, and executive function). The Drug but not the Placebo group showed benefits of treatment at high-load measures by preserving top-down accuracy, improving intra-individual variability, and averting fatigue. In contrast, other global or cognitive domain-specific measures could not detect treatment effects over the same treatment interval. The pilot-study suggests that attention measures targeting accuracy, variability, and fatigue under high-load conditions could be sensitive to short-term cholinergic treatment. Given the central role of acetylcholine in attentional function, load-dependent attentional measures may be valuable cognitive markers of early treatment response.

  6. Effectiveness Analysis of a Part-Time Rapid Response System During Operation Versus Nonoperation.

    PubMed

    Kim, Youlim; Lee, Dong Seon; Min, Hyunju; Choi, Yun Young; Lee, Eun Young; Song, Inae; Park, Jong Sun; Cho, Young-Jae; Jo, You Hwan; Yoon, Ho Il; Lee, Jae Ho; Lee, Choon-Taek; Do, Sang Hwan; Lee, Yeon Joo

    2017-06-01

    To evaluate the effect of a part-time rapid response system on the occurrence rate of cardiopulmonary arrest by comparing the times of rapid response system operation versus nonoperation. Retrospective cohort study. A 1,360-bed tertiary care hospital. Adult patients admitted to the general ward were screened. Data were collected over 36 months from rapid response system implementation (October 2012 to September 2015) and more than 45 months before rapid response system implementation (January 2009 to September 2012). None. The rapid response system operates from 7 AM to 10 PM on weekdays and from 7 AM to 12 PM on Saturdays. Primary outcomes were the difference of cardiopulmonary arrest incidence between pre-rapid response system and post-rapid response system periods and whether the rapid response system operating time affects the cardiopulmonary arrest incidence. The overall cardiopulmonary arrest incidence (per 1,000 admissions) was 1.43. Although the number of admissions per month and case-mix index were increased (3,555.18 vs 4,564.72, p < 0.001; 1.09 vs 1.13, p = 0.001, respectively), the cardiopulmonary arrest incidence was significantly decreased after rapid response system (1.60 vs 1.23; p = 0.021), and mortality (%) was unchanged (1.38 vs 1.33; p = 0.322). After rapid response system implementation, the cardiopulmonary arrest incidence significantly decreased by 40% during rapid response system operating times (0.82 vs 0.49/1,000 admissions; p = 0.001) but remained similar during rapid response system nonoperating times (0.77 vs 0.73/1,000 admissions; p = 0.729). The implementation of a part-time rapid response system reduced the cardiopulmonary arrest incidence based on the reduction of cardiopulmonary arrest during rapid response system operating times. Further analysis of the cost effectiveness of part-time rapid response system is needed.

  7. NOTE: Implementation of angular response function modeling in SPECT simulations with GATE

    NASA Astrophysics Data System (ADS)

    Descourt, P.; Carlier, T.; Du, Y.; Song, X.; Buvat, I.; Frey, E. C.; Bardies, M.; Tsui, B. M. W.; Visvikis, D.

    2010-05-01

    Among Monte Carlo simulation codes in medical imaging, the GATE simulation platform is widely used today given its flexibility and accuracy, despite long run times, which in SPECT simulations are mostly spent in tracking photons through the collimators. In this work, a tabulated model of the collimator/detector response was implemented within the GATE framework to significantly reduce the simulation times in SPECT. This implementation uses the angular response function (ARF) model. The performance of the implemented ARF approach has been compared to standard SPECT GATE simulations in terms of the ARF tables' accuracy, overall SPECT system performance and run times. Considering the simulation of the Siemens Symbia T SPECT system using high-energy collimators, differences of less than 1% were measured between the ARF-based and the standard GATE-based simulations, while considering the same noise level in the projections, acceleration factors of up to 180 were obtained when simulating a planar 364 keV source seen with the same SPECT system. The ARF-based and the standard GATE simulation results also agreed very well when considering a four-head SPECT simulation of a realistic Jaszczak phantom filled with iodine-131, with a resulting acceleration factor of 100. In conclusion, the implementation of an ARF-based model of collimator/detector response for SPECT simulations within GATE significantly reduces the simulation run times without compromising accuracy.

  8. Time-lag effects of global vegetation responses to climate change.

    PubMed

    Wu, Donghai; Zhao, Xiang; Liang, Shunlin; Zhou, Tao; Huang, Kaicheng; Tang, Bijian; Zhao, Wenqian

    2015-09-01

    Climate conditions significantly affect vegetation growth in terrestrial ecosystems. Due to the spatial heterogeneity of ecosystems, the vegetation responses to climate vary considerably with the diverse spatial patterns and the time-lag effects, which are the most important mechanism of climate-vegetation interactive effects. Extensive studies focused on large-scale vegetation-climate interactions use the simultaneous meteorological and vegetation indicators to develop models; however, the time-lag effects are less considered, which tends to increase uncertainty. In this study, we aim to quantitatively determine the time-lag effects of global vegetation responses to different climatic factors using the GIMMS3g NDVI time series and the CRU temperature, precipitation, and solar radiation datasets. First, this study analyzed the time-lag effects of global vegetation responses to different climatic factors. Then, a multiple linear regression model and partial correlation model were established to statistically analyze the roles of different climatic factors on vegetation responses, from which the primary climate-driving factors for different vegetation types were determined. The results showed that (i) both the time-lag effects of the vegetation responses and the major climate-driving factors that significantly affect vegetation growth varied significantly at the global scale, which was related to the diverse vegetation and climate characteristics; (ii) regarding the time-lag effects, the climatic factors explained 64% variation of the global vegetation growth, which was 11% relatively higher than the model ignoring the time-lag effects; (iii) for the area with a significant change trend (for the period 1982-2008) in the global GIMMS3g NDVI (P < 0.05), the primary driving factor was temperature; and (iv) at the regional scale, the variation in vegetation growth was also related to human activities and natural disturbances. Considering the time-lag effects is quite

  9. Cognitive diagnosis modelling incorporating item response times.

    PubMed

    Zhan, Peida; Jiao, Hong; Liao, Dandan

    2018-05-01

    To provide more refined diagnostic feedback with collateral information in item response times (RTs), this study proposed joint modelling of attributes and response speed using item responses and RTs simultaneously for cognitive diagnosis. For illustration, an extended deterministic input, noisy 'and' gate (DINA) model was proposed for joint modelling of responses and RTs. Model parameter estimation was explored using the Bayesian Markov chain Monte Carlo (MCMC) method. The PISA 2012 computer-based mathematics data were analysed first. These real data estimates were treated as true values in a subsequent simulation study. A follow-up simulation study with ideal testing conditions was conducted as well to further evaluate model parameter recovery. The results indicated that model parameters could be well recovered using the MCMC approach. Further, incorporating RTs into the DINA model would improve attribute and profile correct classification rates and result in more accurate and precise estimation of the model parameters. © 2017 The British Psychological Society.

  10. 40 CFR 1066.245 - Response time verification.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... automated process to verify response time. You may perform this test either at two different inertia... base inertia and two acceleration rates that cover the range of acceleration rates experienced during... less than 100 milliseconds for each inertia setting. ER28AP14.066 ...

  11. Task-Based Variability in Children's Singing Accuracy

    ERIC Educational Resources Information Center

    Nichols, Bryan E.

    2016-01-01

    The purpose of this study was to explore the effect of task demands on children's singing accuracy. A 2 × 4 factorial design was used to examine the performance of fourth-grade children (N = 120) in solo and doubled response conditions. Each child sang four task types: single pitch, interval, pattern, and the song "Jingle Bells." The…

  12. Modifying Speech to Children based on their Perceived Phonetic Accuracy

    PubMed Central

    Julien, Hannah M.; Munson, Benjamin

    2014-01-01

    Purpose We examined the relationship between adults' perception of the accuracy of children's speech, and acoustic detail in their subsequent productions to children. Methods Twenty-two adults participated in a task in which they rated the accuracy of 2- and 3-year-old children's word-initial /s/and /∫/ using a visual analog scale (VAS), then produced a token of the same word as if they were responding to the child whose speech they had just rated. Result The duration of adults' fricatives varied as a function of their perception of the accuracy of children's speech: longer fricatives were produced following productions that they rated as inaccurate. This tendency to modify duration in response to perceived inaccurate tokens was mediated by measures of self-reported experience interacting with children. However, speakers did not increase the spectral distinctiveness of their fricatives following the perception of inaccurate tokens. Conclusion These results suggest that adults modify temporal features of their speech in response to perceiving children's inaccurate productions. These longer fricatives are potentially both enhanced input to children, and an error-corrective signal. PMID:22744140

  13. Maintaining tumor targeting accuracy in real-time motion compensation systems for respiration-induced tumor motion.

    PubMed

    Malinowski, Kathleen; McAvoy, Thomas J; George, Rohini; Dieterich, Sonja; D'Souza, Warren D

    2013-07-01

    To determine how best to time respiratory surrogate-based tumor motion model updates by comparing a novel technique based on external measurements alone to three direct measurement methods. Concurrently measured tumor and respiratory surrogate positions from 166 treatment fractions for lung or pancreas lesions were analyzed. Partial-least-squares regression models of tumor position from marker motion were created from the first six measurements in each dataset. Successive tumor localizations were obtained at a rate of once per minute on average. Model updates were timed according to four methods: never, respiratory surrogate-based (when metrics based on respiratory surrogate measurements exceeded confidence limits), error-based (when localization error ≥ 3 mm), and always (approximately once per minute). Radial tumor displacement prediction errors (mean ± standard deviation) for the four schema described above were 2.4 ± 1.2, 1.9 ± 0.9, 1.9 ± 0.8, and 1.7 ± 0.8 mm, respectively. The never-update error was significantly larger than errors of the other methods. Mean update counts over 20 min were 0, 4, 9, and 24, respectively. The same improvement in tumor localization accuracy could be achieved through any of the three update methods, but significantly fewer updates were required when the respiratory surrogate method was utilized. This study establishes the feasibility of timing image acquisitions for updating respiratory surrogate models without direct tumor localization.

  14. Motor responses to a steady beat.

    PubMed

    Schaefer, Rebecca S; Overy, Katie

    2015-03-01

    It is increasingly well established that music containing an isochronous pulse elicits motor responses at the levels of both brain and behavior. Such motor responses are often used in pedagogical and clinical practice to induce movement, particularly where motor functions are impaired. However, the complex nature of such apparently universal human responses has, arguably, not received adequate research attention to date. In particular, it should be noted that many adults, including those with disabilities, find it somewhat difficult to synchronize their movements with a beat with perfect accuracy; indeed, perfecting the skill of being musically "in time" can take years of training during childhood. Further research is needed on the nature of both the specificity and range of motor responses that can arise from the perception of a steady auditory pulse, with different populations, musical stimuli, conditions, and required levels of accuracy in order to better understand and capture the potential value of the musical beat as a pedagogical and therapeutic tool. © 2015 New York Academy of Sciences.

  15. High accuracy autonomous navigation using the global positioning system (GPS)

    NASA Technical Reports Server (NTRS)

    Truong, Son H.; Hart, Roger C.; Shoan, Wendy C.; Wood, Terri; Long, Anne C.; Oza, Dipak H.; Lee, Taesul

    1997-01-01

    The application of global positioning system (GPS) technology to the improvement of the accuracy and economy of spacecraft navigation, is reported. High-accuracy autonomous navigation algorithms are currently being qualified in conjunction with the GPS attitude determination flyer (GADFLY) experiment for the small satellite technology initiative Lewis spacecraft. Preflight performance assessments indicated that these algorithms are able to provide a real time total position accuracy of better than 10 m and a velocity accuracy of better than 0.01 m/s, with selective availability at typical levels. It is expected that the position accuracy will be increased to 2 m if corrections are provided by the GPS wide area augmentation system.

  16. Accuracy of manual entry of drug administration data into an anesthesia information management system.

    PubMed

    Avidan, Alexander; Dotan, Koren; Weissman, Charles; Cohen, Matan J; Levin, Phillip D

    2014-11-01

    Data on drug administration are entered manually into anesthesia information management systems (AIMS). This study examined whether these data are accurate regarding drug name, dose administered, and time of administration, and whether the stage of anesthesia influences data accuracy. Real-time observational data on drug administration during elective operations were compared with computerized information on drug administration entered by anesthesiologists. A trained observer (K.D.) performed the observations. Data were collected during 57 operations which included 596 separate occasions of drug administration by 22 anesthesiologists. No AIMS records were found for 90 (15.1%) occasions of drug administration (omissions), while there were 11 (1.8%) AIMS records where drug administration was not observed. The AIMS and observer data matched for drug name on 495 of 596 (83.1%) occasions, for dose on 439 of 495 (92.5%) occasions, and for time on 476 of 495 (96.2%) occasions. Amongst the 90 omitted records, 34 (37.8%) were for vasoactive drugs with 24 (27.7%) for small doses of hypnotics. Omissions occurred mostly during maintenance: 50 of 153 (24.6%), followed by induction: 30 of 325 (9.2%) and emergence: 10 of 57 (17.5%) (P < 0.001). Time and dose inaccuracies occurred mainly during induction, followed by maintenance and emergence; time inaccuracies were 7/325 (8.3%), 10/203 (4.9%), and 0/57 (0%), respectively (P = 0.07), and dose inaccuracies were 15/325 (4.6%), 3/203 (1.5%), and 1/57 (1.7%), respectively (P = 0.11). The range of accuracy varies when anesthesiologists manually enter drug administration data into an AIMS. Charting omissions represent the largest cause of inaccuracy, principally by omissions of records for vasopressors and small doses of hypnotic drugs. Manually entered drug administration data are not without errors. Accuracy of entering drug administration data remains the responsibility of the anesthesiologist.

  17. 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.

  18. Influence of lidar, Landsat imagery, disturbance history, plot location accuracy, and plot size on accuracy of imputation maps of forest composition and structure

    Treesearch

    Harold S.J. Zald; Janet L. Ohmann; Heather M. Roberts; Matthew J. Gregory; Emilie B. Henderson; Robert J. McGaughey; Justin Braaten

    2014-01-01

    This study investigated how lidar-derived vegetation indices, disturbance history from Landsat time series (LTS) imagery, plot location accuracy, and plot size influenced accuracy of statistical spatial models (nearest-neighbor imputation maps) of forest vegetation composition and structure. Nearest-neighbor (NN) imputation maps were developed for 539,000 ha in the...

  19. Aerial Refueling Simulator Validation Using Operational Experimentation and Response Surface Methods with Time Series Responses

    DTIC Science & Technology

    2013-03-21

    10 2.3 Time Series Response Data ................................................................................. 12 2.4 Comparison of Response...to 12 evaluating the efficiency of the parameter estimates. In the past, the most popular form of response surface design used the D-optimality...as well. A model can refer to almost anything in math , statistics, or computer science. It can be any “physical, mathematical, or logical

  20. 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.

  1. Comparison of Seismic Responses for Reinforced Concrete Buildings with Mass and Stiffness Irregularities Using Pushover and Nonlinear Time History Analysis

    NASA Astrophysics Data System (ADS)

    Teruna, D. R.

    2017-03-01

    Pushover analysis or also known as nonlinear static procedures (NSP) have been recognized in recent years for practical evaluation of seismic demands and for structural design by estimating a structural building capacities and deformation demands. By comparing these demands and capacities at the performance level interest, the seismic performance of a building can be evaluated. However, the accuracy of NSP for assessment irregular building is not yet a fully satisfactory solution, since irregularities of a building influence the dynamic responses of the building. The objective of the study presented herein is to understand the nonlinear behaviour of six story RC building with mass irregularities at different floors and stiffness irregularity at first story (soft story) using NSP. For the purpose of comparison on the performance level obtained with NSP, nonlinear time history analysis (THA) were also performed under ground motion excitation with compatible to response spectra design. Finally, formation plastic hinges and their progressive development from elastic level to collapse prevention are presented and discussed.

  2. Information Gap Analysis: near real-time evaluation of disaster response

    NASA Astrophysics Data System (ADS)

    Girard, Trevor

    2014-05-01

    Disasters, such as major storm events or earthquakes, trigger an immediate response by the disaster management system of the nation in question. The quality of this response is a large factor in its ability to limit the impacts on the local population. Improving the quality of disaster response therefore reduces disaster impacts. Studying past disasters is a valuable exercise to understand what went wrong, identify measures which could have mitigated these issues, and make recommendations to improve future disaster planning and response. While such ex post evaluations can lead to improvements in the disaster management system, there are limitations. The main limitation that has influenced this research is that ex post evaluations do not have the ability to inform the disaster response being assessed for the obvious reason that they are carried out long after the response phase is over. The result is that lessons learned can only be applied to future disasters. In the field of humanitarian relief, this limitation has led to the development of real time evaluations. The key aspect of real time humanitarian evaluations is that they are completed while the operation is still underway. This results in findings being delivered at a time when they can still make a difference to the humanitarian response. Applying such an approach to the immediate disaster response phase requires an even shorter time-frame, as well as a shift in focus from international actors to the nation in question's government. As such, a pilot study was started and methodology developed, to analyze disaster response in near real-time. The analysis uses the information provided by the disaster management system within the first 0 - 5 days of the response. The data is collected from publicly available sources such as ReliefWeb and sorted under various categories which represent each aspect of disaster response. This process was carried out for 12 disasters. The quantity and timeliness of information

  3. Increasing accuracy of pulse transit time measurements by automated elimination of distorted photoplethysmography waves.

    PubMed

    van Velzen, Marit H N; Loeve, Arjo J; Niehof, Sjoerd P; Mik, Egbert G

    2017-11-01

    Photoplethysmography (PPG) is a widely available non-invasive optical technique to visualize pressure pulse waves (PWs). Pulse transit time (PTT) is a physiological parameter that is often derived from calculations on ECG and PPG signals and is based on tightly defined characteristics of the PW shape. PPG signals are sensitive to artefacts. Coughing or movement of the subject can affect PW shapes that much that the PWs become unsuitable for further analysis. The aim of this study was to develop an algorithm that automatically and objectively eliminates unsuitable PWs. In order to develop a proper algorithm for eliminating unsuitable PWs, a literature study was conducted. Next, a '7Step PW-Filter' algorithm was developed that applies seven criteria to determine whether a PW matches the characteristics required to allow PTT calculation. To validate whether the '7Step PW-Filter' eliminates only and all unsuitable PWs, its elimination results were compared to the outcome of manual elimination of unsuitable PWs. The '7Step PW-Filter' had a sensitivity of 96.3% and a specificity of 99.3%. The overall accuracy of the '7Step PW-Filter' for detection of unsuitable PWs was 99.3%. Compared to manual elimination, using the '7Step PW-Filter' reduces PW elimination times from hours to minutes and helps to increase the validity, reliability and reproducibility of PTT data.

  4. Biologically plausible particulate air pollution mortality concentration-response functions.

    PubMed Central

    Roberts, Steven

    2004-01-01

    In this article I introduce an alternative method for estimating particulate air pollution mortality concentration-response functions. This method constrains the particulate air pollution mortality concentration-response function to be biologically plausible--that is, a non-decreasing function of the particulate air pollution concentration. Using time-series data from Cook County, Illinois, the proposed method yields more meaningful particulate air pollution mortality concentration-response function estimates with an increase in statistical accuracy. PMID:14998745

  5. Accuracy assessment in the Large Area Crop Inventory Experiment

    NASA Technical Reports Server (NTRS)

    Houston, A. G.; Pitts, D. E.; Feiveson, A. H.; Badhwar, G.; Ferguson, M.; Hsu, E.; Potter, J.; Chhikara, R.; Rader, M.; Ahlers, C.

    1979-01-01

    The Accuracy Assessment System (AAS) of the Large Area Crop Inventory Experiment (LACIE) was responsible for determining the accuracy and reliability of LACIE estimates of wheat production, area, and yield, made at regular intervals throughout the crop season, and for investigating the various LACIE error sources, quantifying these errors, and relating them to their causes. Some results of using the AAS during the three years of LACIE are reviewed. As the program culminated, AAS was able not only to meet the goal of obtaining accurate statistical estimates of sampling and classification accuracy, but also the goal of evaluating component labeling errors. Furthermore, the ground-truth data processing matured from collecting data for one crop (small grains) to collecting, quality-checking, and archiving data for all crops in a LACIE small segment.

  6. 10 CFR 603.1000 - Contracting officer's responsibilities at time of award.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 4 2010-01-01 2010-01-01 false Contracting officer's responsibilities at time of award. 603.1000 Section 603.1000 Energy DEPARTMENT OF ENERGY (CONTINUED) ASSISTANCE REGULATIONS TECHNOLOGY INVESTMENT AGREEMENTS Executing the Award § 603.1000 Contracting officer's responsibilities at time of award...

  7. Incorporating the gas analyzer response time in gas exchange computations.

    PubMed

    Mitchell, R R

    1979-11-01

    A simple method for including the gas analyzer response time in the breath-by-breath computation of gas exchange rates is described. The method uses a difference equation form of a model for the gas analyzer in the computation of oxygen uptake and carbon dioxide production and avoids a numerical differentiation required to correct the gas fraction wave forms. The effect of not accounting for analyzer response time is shown to be a 20% underestimation in gas exchange rate. The present method accurately measures gas exchange rate, is relatively insensitive to measurement errors in the analyzer time constant, and does not significantly increase the computation time.

  8. Millisecond accuracy video display using OpenGL under Linux.

    PubMed

    Stewart, Neil

    2006-02-01

    To measure people's reaction times to the nearest millisecond, it is necessary to know exactly when a stimulus is displayed. This article describes how to display stimuli with millisecond accuracy on a normal CRT monitor, using a PC running Linux. A simple C program is presented to illustrate how this may be done within X Windows using the OpenGL rendering system. A test of this system is reported that demonstrates that stimuli may be consistently displayed with millisecond accuracy. An algorithm is presented that allows the exact time of stimulus presentation to be deduced, even if there are relatively large errors in measuring the display time.

  9. 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.

  10. High accuracy electronic material level sensor

    DOEpatents

    McEwan, T.E.

    1997-03-11

    The High Accuracy Electronic Material Level Sensor (electronic dipstick) is a sensor based on time domain reflectometry (TDR) of very short electrical pulses. Pulses are propagated along a transmission line or guide wire that is partially immersed in the material being measured; a launcher plate is positioned at the beginning of the guide wire. Reflected pulses are produced at the material interface due to the change in dielectric constant. The time difference of the reflections at the launcher plate and at the material interface are used to determine the material level. Improved performance is obtained by the incorporation of: (1) a high accuracy time base that is referenced to a quartz crystal, (2) an ultrawideband directional sampler to allow operation without an interconnect cable between the electronics module and the guide wire, (3) constant fraction discriminators (CFDs) that allow accurate measurements regardless of material dielectric constants, and reduce or eliminate errors induced by triple-transit or ``ghost`` reflections on the interconnect cable. These improvements make the dipstick accurate to better than 0.1%. 4 figs.

  11. High accuracy electronic material level sensor

    DOEpatents

    McEwan, Thomas E.

    1997-01-01

    The High Accuracy Electronic Material Level Sensor (electronic dipstick) is a sensor based on time domain reflectometry (TDR) of very short electrical pulses. Pulses are propagated along a transmission line or guide wire that is partially immersed in the material being measured; a launcher plate is positioned at the beginning of the guide wire. Reflected pulses are produced at the material interface due to the change in dielectric constant. The time difference of the reflections at the launcher plate and at the material interface are used to determine the material level. Improved performance is obtained by the incorporation of: 1) a high accuracy time base that is referenced to a quartz crystal, 2) an ultrawideband directional sampler to allow operation without an interconnect cable between the electronics module and the guide wire, 3) constant fraction discriminators (CFDs) that allow accurate measurements regardless of material dielectric constants, and reduce or eliminate errors induced by triple-transit or "ghost" reflections on the interconnect cable. These improvements make the dipstick accurate to better than 0.1%.

  12. Accuracy, reliability, and timing of visual evaluations of decay in fresh-cut lettuce

    USDA-ARS?s Scientific Manuscript database

    Visual assessments are used for evaluating the quality of food products, such as fresh-cut lettuce packaged in bags with modified atmosphere. We have compared the accuracy and the reliability of visual evaluations of decay on fresh-cut lettuce performed with experienced and inexperienced raters. In ...

  13. Improving coding accuracy in an academic practice.

    PubMed

    Nguyen, Dana; O'Mara, Heather; Powell, Robert

    2017-01-01

    Practice management has become an increasingly important component of graduate medical education. This applies to every practice environment; private, academic, and military. One of the most critical aspects of practice management is documentation and coding for physician services, as they directly affect the financial success of any practice. Our quality improvement project aimed to implement a new and innovative method for teaching billing and coding in a longitudinal fashion in a family medicine residency. We hypothesized that implementation of a new teaching strategy would increase coding accuracy rates among residents and faculty. Design: single group, pretest-posttest. military family medicine residency clinic. Study populations: 7 faculty physicians and 18 resident physicians participated as learners in the project. Educational intervention: monthly structured coding learning sessions in the academic curriculum that involved learner-presented cases, small group case review, and large group discussion. overall coding accuracy (compliance) percentage and coding accuracy per year group for the subjects that were able to participate longitudinally. Statistical tests used: average coding accuracy for population; paired t test to assess improvement between 2 intervention periods, both aggregate and by year group. Overall coding accuracy rates remained stable over the course of time regardless of the modality of the educational intervention. A paired t test was conducted to compare coding accuracy rates at baseline (mean (M)=26.4%, SD=10%) to accuracy rates after all educational interventions were complete (M=26.8%, SD=12%); t24=-0.127, P=.90. Didactic teaching and small group discussion sessions did not improve overall coding accuracy in a residency practice. Future interventions could focus on educating providers at the individual level.

  14. Improving substructure identification accuracy of shear structures using virtual control system

    NASA Astrophysics Data System (ADS)

    Zhang, Dongyu; Yang, Yang; Wang, Tingqiang; Li, Hui

    2018-02-01

    Substructure identification is a powerful tool to identify the parameters of a complex structure. Previously, the authors developed an inductive substructure identification method for shear structures. The identification error analysis showed that the identification accuracy of this method is significantly influenced by the magnitudes of two key structural responses near a certain frequency; if these responses are unfavorable, the method cannot provide accurate estimation results. In this paper, a novel method is proposed to improve the substructure identification accuracy by introducing a virtual control system (VCS) into the structure. A virtual control system is a self-balanced system, which consists of some control devices and a set of self-balanced forces. The self-balanced forces counterbalance the forces that the control devices apply on the structure. The control devices are combined with the structure to form a controlled structure used to replace the original structure in the substructure identification; and the self-balance forces are treated as known external excitations to the controlled structure. By optimally tuning the VCS’s parameters, the dynamic characteristics of the controlled structure can be changed such that the original structural responses become more favorable for the substructure identification and, thus, the identification accuracy is improved. A numerical example of 6-story shear structure is utilized to verify the effectiveness of the VCS based controlled substructure identification method. Finally, shake table tests are conducted on a 3-story structural model to verify the efficacy of the VCS to enhance the identification accuracy of the structural parameters.

  15. Effects of Turbulence Model and Numerical Time Steps on Von Karman Flow Behavior and Drag Accuracy of Circular Cylinder

    NASA Astrophysics Data System (ADS)

    Amalia, E.; Moelyadi, M. A.; Ihsan, M.

    2018-04-01

    The flow of air passing around a circular cylinder on the Reynolds number of 250,000 is to show Von Karman Vortex Street Phenomenon. This phenomenon was captured well by using a right turbulence model. In this study, some turbulence models available in software ANSYS Fluent 16.0 was tested to simulate Von Karman vortex street phenomenon, namely k- epsilon, SST k-omega and Reynolds Stress, Detached Eddy Simulation (DES), and Large Eddy Simulation (LES). In addition, it was examined the effect of time step size on the accuracy of CFD simulation. The simulations are carried out by using two-dimensional and three- dimensional models and then compared with experimental data. For two-dimensional model, Von Karman Vortex Street phenomenon was captured successfully by using the SST k-omega turbulence model. As for the three-dimensional model, Von Karman Vortex Street phenomenon was captured by using Reynolds Stress Turbulence Model. The time step size value affects the smoothness quality of curves of drag coefficient over time, as well as affecting the running time of the simulation. The smaller time step size, the better inherent drag coefficient curves produced. Smaller time step size also gives faster computation time.

  16. Time-Lapse and Slow-Motion Tracking of Temperature Changes: Response Time of a Thermometer

    ERIC Educational Resources Information Center

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

    2017-01-01

    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…

  17. Predictive Accuracy of Exercise Stress Testing the Healthy Adult.

    ERIC Educational Resources Information Center

    Lamont, Linda S.

    1981-01-01

    Exercise stress testing provides information on the aerobic capacity, heart rate, and blood pressure responses to graded exercises of a healthy adult. The reliability of exercise tests as a diagnostic procedure is discussed in relation to sensitivity and specificity and predictive accuracy. (JN)

  18. 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

  19. A Time Integration Algorithm Based on the State Transition Matrix for Structures with Time Varying and Nonlinear Properties

    NASA Technical Reports Server (NTRS)

    Bartels, Robert E.

    2003-01-01

    A variable order method of integrating the structural dynamics equations that is based on the state transition matrix has been developed. The method has been evaluated for linear time variant and nonlinear systems of equations. When the time variation of the system can be modeled exactly by a polynomial it produces nearly exact solutions for a wide range of time step sizes. Solutions of a model nonlinear dynamic response exhibiting chaotic behavior have been computed. Accuracy of the method has been demonstrated by comparison with solutions obtained by established methods.

  20. Maintaining tumor targeting accuracy in real-time motion compensation systems for respiration-induced tumor motion

    PubMed Central

    Malinowski, Kathleen; McAvoy, Thomas J.; George, Rohini; Dieterich, Sonja; D’Souza, Warren D.

    2013-01-01

    Purpose: To determine how best to time respiratory surrogate-based tumor motion model updates by comparing a novel technique based on external measurements alone to three direct measurement methods. Methods: Concurrently measured tumor and respiratory surrogate positions from 166 treatment fractions for lung or pancreas lesions were analyzed. Partial-least-squares regression models of tumor position from marker motion were created from the first six measurements in each dataset. Successive tumor localizations were obtained at a rate of once per minute on average. Model updates were timed according to four methods: never, respiratory surrogate-based (when metrics based on respiratory surrogate measurements exceeded confidence limits), error-based (when localization error ≥3 mm), and always (approximately once per minute). Results: Radial tumor displacement prediction errors (mean ± standard deviation) for the four schema described above were 2.4 ± 1.2, 1.9 ± 0.9, 1.9 ± 0.8, and 1.7 ± 0.8 mm, respectively. The never-update error was significantly larger than errors of the other methods. Mean update counts over 20 min were 0, 4, 9, and 24, respectively. Conclusions: The same improvement in tumor localization accuracy could be achieved through any of the three update methods, but significantly fewer updates were required when the respiratory surrogate method was utilized. This study establishes the feasibility of timing image acquisitions for updating respiratory surrogate models without direct tumor localization. PMID:23822413

  1. On the subsystem formulation of linear-response time-dependent DFT.

    PubMed

    Pavanello, Michele

    2013-05-28

    A new and thorough derivation of linear-response subsystem time-dependent density functional theory (TD-DFT) is presented and analyzed in detail. Two equivalent derivations are presented and naturally yield self-consistent subsystem TD-DFT equations. One reduces to the subsystem TD-DFT formalism of Neugebauer [J. Chem. Phys. 126, 134116 (2007)]. The other yields Dyson type equations involving three types of subsystem response functions: coupled, uncoupled, and Kohn-Sham. The Dyson type equations for subsystem TD-DFT are derived here for the first time. The response function formalism reveals previously hidden qualities and complications of subsystem TD-DFT compared with the regular TD-DFT of the supersystem. For example, analysis of the pole structure of the subsystem response functions shows that each function contains information about the electronic spectrum of the entire supersystem. In addition, comparison of the subsystem and supersystem response functions shows that, while the correlated response is subsystem additive, the Kohn-Sham response is not. Comparison with the non-subjective partition DFT theory shows that this non-additivity is largely an artifact introduced by the subjective nature of the density partitioning in subsystem DFT.

  2. Evaluation of mechanical accuracy for couch‐based tracking system (CBTS)

    PubMed Central

    Lee, Suk; Chang, Kyung‐Hwan; Shim, Jand Bo; Cao, Yuanjie; Lee, Chang Ki; Cho, Sam Ju; Yang, Dae Sik; Park, Young Je; Yoon, Won Seob

    2012-01-01

    This study evaluated the mechanical accuracy of an in‐house–developed couch‐based tracking system (CBTS) according to respiration data. The overall delay time of the CBTS was calculated, and the accuracy, reproducibility, and loading effect of the CBTS were evaluated according to the sinusoidal waveform and various respiratory motion data of real patients with and without a volunteer weighing 75 kg. The root mean square (rms) error of the accuracy, the reproducibility, and the sagging measurements were calculated for the three axes (X, Y, and Z directions) of the CBTS. The overall delay time of the CBTS was 0.251 sec. The accuracy and reproducibility in the Z direction in real patient data were poor, as indicated by high rms errors. The results of the loading effect were within 1.0 mm in all directions. This novel CBTS has the potential for clinical application for tumor tracking in radiation therapy. PACS number: 87.55.ne PMID:23149775

  3. Empirical Accuracies of U.S. Space Surveillance Network Reentry Predictions

    NASA Technical Reports Server (NTRS)

    Johnson, Nicholas L.

    2008-01-01

    The U.S. Space Surveillance Network (SSN) issues formal satellite reentry predictions for objects which have the potential for generating debris which could pose a hazard to people or property on Earth. These prognostications, known as Tracking and Impact Prediction (TIP) messages, are nominally distributed at daily intervals beginning four days prior to the anticipated reentry and several times during the final 24 hours in orbit. The accuracy of these messages depends on the nature of the satellite s orbit, the characteristics of the space vehicle, solar activity, and many other factors. Despite the many influences on the time and the location of reentry, a useful assessment of the accuracies of TIP messages can be derived and compared with the official accuracies included with each TIP message. This paper summarizes the results of a study of numerous uncontrolled reentries of spacecraft and rocket bodies from nearly circular orbits over a span of several years. Insights are provided into the empirical accuracies and utility of SSN TIP messages.

  4. Corrective response times in a coordinated eye-head-arm countermanding task.

    PubMed

    Tao, Gordon; Khan, Aarlenne Z; Blohm, Gunnar

    2018-06-01

    Inhibition of motor responses has been described as a race between two competing decision processes of motor initiation and inhibition, which manifest as the reaction time (RT) and the stop signal reaction time (SSRT); in the case where motor initiation wins out over inhibition, an erroneous movement occurs that usually needs to be corrected, leading to corrective response times (CRTs). Here we used a combined eye-head-arm movement countermanding task to investigate the mechanisms governing multiple effector coordination and the timing of corrective responses. We found a high degree of correlation between effector response times for RT, SSRT, and CRT, suggesting that decision processes are strongly dependent across effectors. To gain further insight into the mechanisms underlying CRTs, we tested multiple models to describe the distribution of RTs, SSRTs, and CRTs. The best-ranked model (according to 3 information criteria) extends the LATER race model governing RTs and SSRTs, whereby a second motor initiation process triggers the corrective response (CRT) only after the inhibition process completes in an expedited fashion. Our model suggests that the neural processing underpinning a failed decision has a residual effect on subsequent actions. NEW & NOTEWORTHY Failure to inhibit erroneous movements typically results in corrective movements. For coordinated eye-head-hand movements we show that corrective movements are only initiated after the erroneous movement cancellation signal has reached a decision threshold in an accelerated fashion.

  5. 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…

  6. 22 CFR 706.30 - Timing of responses to requests.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 706.30 Foreign Relations OVERSEAS PRIVATE INVESTMENT CORPORATION ADMINISTRATIVE PROVISIONS INFORMATION DISCLOSURE UNDER THE FREEDOM OF INFORMATION ACT Processing of Requests § 706.30 Timing of responses to... information; (2) A request for expedited processing may be made at any time. (3) A requester who seeks...

  7. Dynamical synapses enhance neural information processing: gracefulness, accuracy, and mobility.

    PubMed

    Fung, C C Alan; Wong, K Y Michael; Wang, He; Wu, Si

    2012-05-01

    Experimental data have revealed that neuronal connection efficacy exhibits two forms of short-term plasticity: short-term depression (STD) and short-term facilitation (STF). They have time constants residing between fast neural signaling and rapid learning and may serve as substrates for neural systems manipulating temporal information on relevant timescales. This study investigates the impact of STD and STF on the dynamics of continuous attractor neural networks and their potential roles in neural information processing. We find that STD endows the network with slow-decaying plateau behaviors: the network that is initially being stimulated to an active state decays to a silent state very slowly on the timescale of STD rather than on that of neuralsignaling. This provides a mechanism for neural systems to hold sensory memory easily and shut off persistent activities gracefully. With STF, we find that the network can hold a memory trace of external inputs in the facilitated neuronal interactions, which provides a way to stabilize the network response to noisy inputs, leading to improved accuracy in population decoding. Furthermore, we find that STD increases the mobility of the network states. The increased mobility enhances the tracking performance of the network in response to time-varying stimuli, leading to anticipative neural responses. In general, we find that STD and STP tend to have opposite effects on network dynamics and complementary computational advantages, suggesting that the brain may employ a strategy of weighting them differentially depending on the computational purpose.

  8. Adaptive time-variant models for fuzzy-time-series forecasting.

    PubMed

    Wong, Wai-Keung; Bai, Enjian; Chu, Alice Wai-Ching

    2010-12-01

    A fuzzy time series has been applied to the prediction of enrollment, temperature, stock indices, and other domains. Related studies mainly focus on three factors, namely, the partition of discourse, the content of forecasting rules, and the methods of defuzzification, all of which greatly influence the prediction accuracy of forecasting models. These studies use fixed analysis window sizes for forecasting. In this paper, an adaptive time-variant fuzzy-time-series forecasting model (ATVF) is proposed to improve forecasting accuracy. The proposed model automatically adapts the analysis window size of fuzzy time series based on the prediction accuracy in the training phase and uses heuristic rules to generate forecasting values in the testing phase. The performance of the ATVF model is tested using both simulated and actual time series including the enrollments at the University of Alabama, Tuscaloosa, and the Taiwan Stock Exchange Capitalization Weighted Stock Index (TAIEX). The experiment results show that the proposed ATVF model achieves a significant improvement in forecasting accuracy as compared to other fuzzy-time-series forecasting models.

  9. 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)…

  10. Lunar Reconnaissance Orbiter Orbit Determination Accuracy Analysis

    NASA Technical Reports Server (NTRS)

    Slojkowski, Steven E.

    2014-01-01

    Results from operational OD produced by the NASA Goddard Flight Dynamics Facility for the LRO nominal and extended mission are presented. During the LRO nominal mission, when LRO flew in a low circular orbit, orbit determination requirements were met nearly 100% of the time. When the extended mission began, LRO returned to a more elliptical frozen orbit where gravity and other modeling errors caused numerous violations of mission accuracy requirements. Prediction accuracy is particularly challenged during periods when LRO is in full-Sun. A series of improvements to LRO orbit determination are presented, including implementation of new lunar gravity models, improved spacecraft solar radiation pressure modeling using a dynamic multi-plate area model, a shorter orbit determination arc length, and a constrained plane method for estimation. The analysis presented in this paper shows that updated lunar gravity models improved accuracy in the frozen orbit, and a multiplate dynamic area model improves prediction accuracy during full-Sun orbit periods. Implementation of a 36-hour tracking data arc and plane constraints during edge-on orbit geometry also provide benefits. A comparison of the operational solutions to precision orbit determination solutions shows agreement on a 100- to 250-meter level in definitive accuracy.

  11. 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

  12. Modeling in Real Time During the Ebola Response.

    PubMed

    Meltzer, Martin I; Santibanez, Scott; Fischer, Leah S; Merlin, Toby L; Adhikari, Bishwa B; Atkins, Charisma Y; Campbell, Caresse; Fung, Isaac Chun-Hai; Gambhir, Manoj; Gift, Thomas; Greening, Bradford; Gu, Weidong; Jacobson, Evin U; Kahn, Emily B; Carias, Cristina; Nerlander, Lina; Rainisch, Gabriel; Shankar, Manjunath; Wong, Karen; Washington, Michael L

    2016-07-08

    To aid decision-making during CDC's response to the 2014-2016 Ebola virus disease (Ebola) epidemic in West Africa, CDC activated a Modeling Task Force to generate estimates on various topics related to the response in West Africa and the risk for importation of cases into the United States. Analysis of eight Ebola response modeling projects conducted during August 2014-July 2015 provided insight into the types of questions addressed by modeling, the impact of the estimates generated, and the difficulties encountered during the modeling. This time frame was selected to cover the three phases of the West African epidemic curve. Questions posed to the Modeling Task Force changed as the epidemic progressed. Initially, the task force was asked to estimate the number of cases that might occur if no interventions were implemented compared with cases that might occur if interventions were implemented; however, at the peak of the epidemic, the focus shifted to estimating resource needs for Ebola treatment units. Then, as the epidemic decelerated, requests for modeling changed to generating estimates of the potential number of sexually transmitted Ebola cases. Modeling to provide information for decision-making during the CDC Ebola response involved limited data, a short turnaround time, and difficulty communicating the modeling process, including assumptions and interpretation of results. Despite these challenges, modeling yielded estimates and projections that public health officials used to make key decisions regarding response strategy and resources required. The impact of modeling during the Ebola response demonstrates the usefulness of modeling in future responses, particularly in the early stages and when data are scarce. Future modeling can be enhanced by planning ahead for data needs and data sharing, and by open communication among modelers, scientists, and others to ensure that modeling and its limitations are more clearly understood. The activities summarized in

  13. 45 CFR 612.5 - Timing of responses to requests.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ....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. The NSF and... engaged in disseminating information. (ii) For example, a requester who is not a full-time member of the...

  14. A very low noise, high accuracy, programmable voltage source for low frequency noise measurements

    NASA Astrophysics Data System (ADS)

    Scandurra, Graziella; Giusi, Gino; Ciofi, Carmine

    2014-04-01

    In this paper an approach for designing a programmable, very low noise, high accuracy voltage source for biasing devices under test in low frequency noise measurements is proposed. The core of the system is a supercapacitor based two pole low pass filter used for filtering out the noise produced by a standard DA converter down to 100 mHz with an attenuation in excess of 40 dB. The high leakage current of the supercapacitors, however, introduces large DC errors that need to be compensated in order to obtain high accuracy as well as very low output noise. To this end, a proper circuit topology has been developed that allows to considerably reduce the effect of the supercapacitor leakage current on the DC response of the system while maintaining a very low level of output noise. With a proper design an output noise as low as the equivalent input voltage noise of the OP27 operational amplifier, used as the output buffer of the system, can be obtained with DC accuracies better that 0.05% up to the maximum output of 8 V. The expected performances of the proposed voltage source have been confirmed both by means of SPICE simulations and by means of measurements on actual prototypes. Turn on and stabilization times for the system are of the order of a few hundred seconds. These times are fully compatible with noise measurements down to 100 mHz, since measurement times of the order of several tens of minutes are required in any case in order to reduce the statistical error in the measured spectra down to an acceptable level.

  15. A very low noise, high accuracy, programmable voltage source for low frequency noise measurements.

    PubMed

    Scandurra, Graziella; Giusi, Gino; Ciofi, Carmine

    2014-04-01

    In this paper an approach for designing a programmable, very low noise, high accuracy voltage source for biasing devices under test in low frequency noise measurements is proposed. The core of the system is a supercapacitor based two pole low pass filter used for filtering out the noise produced by a standard DA converter down to 100 mHz with an attenuation in excess of 40 dB. The high leakage current of the supercapacitors, however, introduces large DC errors that need to be compensated in order to obtain high accuracy as well as very low output noise. To this end, a proper circuit topology has been developed that allows to considerably reduce the effect of the supercapacitor leakage current on the DC response of the system while maintaining a very low level of output noise. With a proper design an output noise as low as the equivalent input voltage noise of the OP27 operational amplifier, used as the output buffer of the system, can be obtained with DC accuracies better that 0.05% up to the maximum output of 8 V. The expected performances of the proposed voltage source have been confirmed both by means of SPICE simulations and by means of measurements on actual prototypes. Turn on and stabilization times for the system are of the order of a few hundred seconds. These times are fully compatible with noise measurements down to 100 mHz, since measurement times of the order of several tens of minutes are required in any case in order to reduce the statistical error in the measured spectra down to an acceptable level.

  16. Working memory accuracy for multiple targets is driven by reward expectation and stimulus contrast with different time-courses.

    PubMed

    Klink, P Christiaan; Jeurissen, Danique; Theeuwes, Jan; Denys, Damiaan; Roelfsema, Pieter R

    2017-08-22

    The richness of sensory input dictates that the brain must prioritize and select information for further processing and storage in working memory. Stimulus salience and reward expectations influence this prioritization but their relative contributions and underlying mechanisms are poorly understood. Here we investigate how the quality of working memory for multiple stimuli is determined by priority during encoding and later memory phases. Selective attention could, for instance, act as the primary gating mechanism when stimuli are still visible. Alternatively, observers might still be able to shift priorities across memories during maintenance or retrieval. To distinguish between these possibilities, we investigated how and when reward cues determine working memory accuracy and found that they were only effective during memory encoding. Previously learned, but currently non-predictive, color-reward associations had a similar influence, which gradually weakened without reinforcement. Finally, we show that bottom-up salience, manipulated through varying stimulus contrast, influences memory accuracy during encoding with a fundamentally different time-course than top-down reward cues. While reward-based effects required long stimulus presentation, the influence of contrast was strongest with brief presentations. Our results demonstrate how memory resources are distributed over memory targets and implicates selective attention as a main gating mechanism between sensory and memory systems.

  17. Effects of increasing time delays on pitch-matching accuracy in trained singers and untrained individuals.

    PubMed

    Estis, Julie M; Coblentz, Joana K; Moore, Robert E

    2009-07-01

    Trained singers (TS) generally demonstrate accurate pitch matching, but this ability varies within the general population. Pitch-matching accuracy, given increasing silence intervals of 5, 15, and 25 seconds between target tones and vocal matches, was investigated in TS and untrained individuals. A relationship between pitch discrimination and pitch matching was also examined. Thirty-two females (20-30 years) were grouped based on individual vocal training and performance in an immediate pitch-matching task. Participants matched target pitches following time delays, and completed a pitch discrimination task, which required the classification of two tones as same or different. TS and untrained accurate participants performed comparably on all pitch-matching tasks, while untrained inaccurate participants performed significantly less accurately than the other two groups. Performances declined across groups as intervals of silence increased, suggesting degradation of pitch matching as pitch memory was taxed. A significant relationship between pitch discrimination and pitch matching was revealed across participants.

  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. Additional Evidence for the Accuracy of Biographical Data: Long-Term Retest and Observer Ratings.

    ERIC Educational Resources Information Center

    Shaffer, Garnett Stokes; And Others

    1986-01-01

    Investigated accuracy of responses to biodata questionnaire using a test-retest design and informed external observers for verification. Responses from 237 subjects and 200 observers provided evidence that many responses to biodata questionnaire were accurate. Assessed sources of inaccuracy, including social desirability effects, and noted…

  20. The accuracy and efficacy of real-time continuous glucose monitoring sensor in Chinese diabetes patients: a multicenter study.

    PubMed

    Zhou, Jian; Lv, Xiaofeng; Mu, Yiming; Wang, Xianling; Li, Jing; Zhang, Xingguang; Wu, Jinxiao; Bao, Yuqian; Jia, Weiping

    2012-08-01

    The purpose of this multicenter study was to investigate the accuracy of a real-time continuous glucose monitoring sensor in Chinese diabetes patients. In total, 48 patients with type 1 or 2 diabetes from three centers in China were included in the study. The MiniMed Paradigm(®) 722 insulin pump (Medtronic, Northridge, CA) was used to monitor the real-time continuous changes of blood glucose levels for three successive days. Venous blood of the subjects was randomly collected every 15 min for seven consecutive hours on the day when the subjects were wearing the sensor. Reference values were provided by the YSI(®) 2300 STAT PLUS™ glucose and lactate analyzer (YSI Life Sciences, Yellow Springs, OH). In total, 1,317 paired YSI-sensor values were collected from the 48 patients. Of the sensor readings, 88.3% (95% confidence interval, 0.84-0.92) were within±20% of the YSI values, and 95.7% were within±30% of the YSI values. Clarke and consensus error grid analyses showed that the ratios of the YSI-sensor values in Zone A to the values in Zone B were 99.1% and 99.9%, respectively. Continuous error grid analysis showed that the ratios of the YSI-sensor values in the region of accurate reading, benign errors, and erroneous reading were 96.4%, 1.8%, and 1.8%, respectively. The mean absolute relative difference (ARD) for all subjects was 10.4%, and the median ARD was 7.8%. Bland-Altman analysis detected a mean blood glucose level of 3.84 mg/dL. Trend analysis revealed that 86.1% of the difference of the rates of change between the YSI values and the sensor readings occurred within the range of 1 mg/dL/min. The Paradigm insulin pump has high accuracy in both monitoring the real-time continuous changes and predicting the trend of changes in blood glucose level. However, actual clinical manifestations should be taken into account for diagnosis of hypoglycemia.

  1. Accuracy of remotely sensed data: Sampling and analysis procedures

    NASA Technical Reports Server (NTRS)

    Congalton, R. G.; Oderwald, R. G.; Mead, R. A.

    1982-01-01

    A review and update of the discrete multivariate analysis techniques used for accuracy assessment is given. A listing of the computer program written to implement these techniques is given. New work on evaluating accuracy assessment using Monte Carlo simulation with different sampling schemes is given. The results of matrices from the mapping effort of the San Juan National Forest is given. A method for estimating the sample size requirements for implementing the accuracy assessment procedures is given. A proposed method for determining the reliability of change detection between two maps of the same area produced at different times is given.

  2. Influence of sleep deprivation and auditory intensity on reaction time and response force.

    PubMed

    Włodarczyk, Dariusz; Jaśkowski, Piotr; Nowik, Agnieszka

    2002-06-01

    Arousal and activation are two variables supposed to underlie change in response force. This study was undertaken to explain these roles, specifically, for strong auditory stimuli and sleep deficit. Loud auditory stimuli can evoke phasic overarousal whereas sleep deficit leads to general underarousal. Moreover, Van der Molen and Keuss (1979, 1981) showed that paradoxically long reaction times occurred with extremely strong auditory stimuli when the task was difficult, e.g., choice reaction or Simon paradigm. It was argued that this paradoxical behavior related to reaction time is due to active disconnecting of the coupling between arousal and activation to prevent false responses. If so, we predicted that for extremely loud stimuli and for difficult tasks, the lengthening of reaction time should be associated with reduction of response force. The effects of loudness and sleep deficit on response time and force were investigated in three different tasks: simple response, choice response, and Simon paradigm. According to our expectation, we found a detrimental effect of sleep deficit on reaction time and on response force. In contrast to Van der Molen and Keuss, we found no increase in reaction time for loud stimuli (up to 110 dB) even on the Simon task.

  3. Quantification and classification of neuronal responses in kernel-smoothed peristimulus time histograms

    PubMed Central

    Fried, Itzhak; Koch, Christof

    2014-01-01

    Peristimulus time histograms are a widespread form of visualizing neuronal responses. Kernel convolution methods transform these histograms into a smooth, continuous probability density function. This provides an improved estimate of a neuron's actual response envelope. We here develop a classifier, called the h-coefficient, to determine whether time-locked fluctuations in the firing rate of a neuron should be classified as a response or as random noise. Unlike previous approaches, the h-coefficient takes advantage of the more precise response envelope estimation provided by the kernel convolution method. The h-coefficient quantizes the smoothed response envelope and calculates the probability of a response of a given shape to occur by chance. We tested the efficacy of the h-coefficient in a large data set of Monte Carlo simulated smoothed peristimulus time histograms with varying response amplitudes, response durations, trial numbers, and baseline firing rates. Across all these conditions, the h-coefficient significantly outperformed more classical classifiers, with a mean false alarm rate of 0.004 and a mean hit rate of 0.494. We also tested the h-coefficient's performance in a set of neuronal responses recorded in humans. The algorithm behind the h-coefficient provides various opportunities for further adaptation and the flexibility to target specific parameters in a given data set. Our findings confirm that the h-coefficient can provide a conservative and powerful tool for the analysis of peristimulus time histograms with great potential for future development. PMID:25475352

  4. Locating helicopter emergency medical service bases to optimise population coverage versus average response time.

    PubMed

    Garner, Alan A; van den Berg, Pieter L

    2017-10-16

    New South Wales (NSW), Australia has a network of multirole retrieval physician staffed helicopter emergency medical services (HEMS) with seven bases servicing a jurisdiction with population concentrated along the eastern seaboard. The aim of this study was to estimate optimal HEMS base locations within NSW using advanced mathematical modelling techniques. We used high resolution census population data for NSW from 2011 which divides the state into areas containing 200-800 people. Optimal HEMS base locations were estimated using the maximal covering location problem facility location optimization model and the average response time model, exploring the number of bases needed to cover various fractions of the population for a 45 min response time threshold or minimizing the overall average response time to all persons, both in green field scenarios and conditioning on the current base structure. We also developed a hybrid mathematical model where average response time was optimised based on minimum population coverage thresholds. Seven bases could cover 98% of the population within 45mins when optimised for coverage or reach the entire population of the state within an average of 21mins if optimised for response time. Given the existing bases, adding two bases could either increase the 45 min coverage from 91% to 97% or decrease the average response time from 21mins to 19mins. Adding a single specialist prehospital rapid response HEMS to the area of greatest population concentration decreased the average state wide response time by 4mins. The optimum seven base hybrid model that was able to cover 97.75% of the population within 45mins, and all of the population in an average response time of 18 mins included the rapid response HEMS model. HEMS base locations can be optimised based on either percentage of the population covered, or average response time to the entire population. We have also demonstrated a hybrid technique that optimizes response time for a given

  5. The speed of metacognition: taking time to get to know one's structural knowledge.

    PubMed

    Mealor, Andy D; Dienes, Zoltan

    2013-03-01

    The time course of different metacognitive experiences of knowledge was investigated using artificial grammar learning. Experiment 1 revealed that when participants are aware of the basis of their judgments (conscious structural knowledge) decisions are made most rapidly, followed by decisions made with conscious judgment but without conscious knowledge of underlying structure (unconscious structural knowledge), and guess responses (unconscious judgment knowledge) were made most slowly, even when controlling for differences in confidence and accuracy. In experiment 2, short response deadlines decreased the accuracy of unconscious but not conscious structural knowledge. Conversely, the deadline decreased the proportion of conscious structural knowledge in favour of guessing. Unconscious structural knowledge can be applied rapidly but becomes more reliable with additional metacognitive processing time whereas conscious structural knowledge is an all-or-nothing response that cannot always be applied rapidly. These dissociations corroborate quite separate theories of recognition (dual-process) and metacognition (higher order thought and cross-order integration). Copyright © 2012 Elsevier Inc. All rights reserved.

  6. Accuracy and Resolution in Micro-earthquake Tomographic Inversion Studies

    NASA Astrophysics Data System (ADS)

    Hutchings, L. J.; Ryan, J.

    2010-12-01

    Accuracy and resolution are complimentary properties necessary to interpret the results of earthquake location and tomography studies. Accuracy is the how close an answer is to the “real world”, and resolution is who small of node spacing or earthquake error ellipse one can achieve. We have modified SimulPS (Thurber, 1986) in several ways to provide a tool for evaluating accuracy and resolution of potential micro-earthquake networks. First, we provide synthetic travel times from synthetic three-dimensional geologic models and earthquake locations. We use this to calculate errors in earthquake location and velocity inversion results when we perturb these models and try to invert to obtain these models. We create as many stations as desired and can create a synthetic velocity model with any desired node spacing. We apply this study to SimulPS and TomoDD inversion studies. “Real” travel times are perturbed with noise and hypocenters are perturbed to replicate a starting location away from the “true” location, and inversion is performed by each program. We establish travel times with the pseudo-bending ray tracer and use the same ray tracer in the inversion codes. This, of course, limits our ability to test the accuracy of the ray tracer. We developed relationships for the accuracy and resolution expected as a function of the number of earthquakes and recording stations for typical tomographic inversion studies. Velocity grid spacing started at 1km, then was decreased to 500m, 100m, 50m and finally 10m to see if resolution with decent accuracy at that scale was possible. We considered accuracy to be good when we could invert a velocity model perturbed by 50% back to within 5% of the original model, and resolution to be the size of the grid spacing. We found that 100 m resolution could obtained by using 120 stations with 500 events, bu this is our current limit. The limiting factors are the size of computers needed for the large arrays in the inversion and a

  7. High accuracy satellite drag model (HASDM)

    NASA Astrophysics Data System (ADS)

    Storz, Mark F.; Bowman, Bruce R.; Branson, Major James I.; Casali, Stephen J.; Tobiska, W. Kent

    The dominant error source in force models used to predict low-perigee satellite trajectories is atmospheric drag. Errors in operational thermospheric density models cause significant errors in predicted satellite positions, since these models do not account for dynamic changes in atmospheric drag for orbit predictions. The Air Force Space Battlelab's High Accuracy Satellite Drag Model (HASDM) estimates and predicts (out three days) a dynamically varying global density field. HASDM includes the Dynamic Calibration Atmosphere (DCA) algorithm that solves for the phases and amplitudes of the diurnal and semidiurnal variations of thermospheric density near real-time from the observed drag effects on a set of Low Earth Orbit (LEO) calibration satellites. The density correction is expressed as a function of latitude, local solar time and altitude. In HASDM, a time series prediction filter relates the extreme ultraviolet (EUV) energy index E10.7 and the geomagnetic storm index ap, to the DCA density correction parameters. The E10.7 index is generated by the SOLAR2000 model, the first full spectrum model of solar irradiance. The estimated and predicted density fields will be used operationally to significantly improve the accuracy of predicted trajectories for all low-perigee satellites.

  8. Estimated Accuracy of Three Common Trajectory Statistical Methods

    NASA Technical Reports Server (NTRS)

    Kabashnikov, Vitaliy P.; Chaikovsky, Anatoli P.; Kucsera, Tom L.; Metelskaya, Natalia S.

    2011-01-01

    Three well-known trajectory statistical methods (TSMs), namely concentration field (CF), concentration weighted trajectory (CWT), and potential source contribution function (PSCF) methods were tested using known sources and artificially generated data sets to determine the ability of TSMs to reproduce spatial distribution of the sources. In the works by other authors, the accuracy of the trajectory statistical methods was estimated for particular species and at specified receptor locations. We have obtained a more general statistical estimation of the accuracy of source reconstruction and have found optimum conditions to reconstruct source distributions of atmospheric trace substances. Only virtual pollutants of the primary type were considered. In real world experiments, TSMs are intended for application to a priori unknown sources. Therefore, the accuracy of TSMs has to be tested with all possible spatial distributions of sources. An ensemble of geographical distributions of virtual sources was generated. Spearman s rank order correlation coefficient between spatial distributions of the known virtual and the reconstructed sources was taken to be a quantitative measure of the accuracy. Statistical estimates of the mean correlation coefficient and a range of the most probable values of correlation coefficients were obtained. All the TSMs that were considered here showed similar close results. The maximum of the ratio of the mean correlation to the width of the correlation interval containing the most probable correlation values determines the optimum conditions for reconstruction. An optimal geographical domain roughly coincides with the area supplying most of the substance to the receptor. The optimal domain s size is dependent on the substance decay time. Under optimum reconstruction conditions, the mean correlation coefficients can reach 0.70 0.75. The boundaries of the interval with the most probable correlation values are 0.6 0.9 for the decay time of 240 h

  9. The paradox of verbal autopsy in cause of death assignment: symptom question unreliability but predictive accuracy.

    PubMed

    Serina, Peter; Riley, Ian; Hernandez, Bernardo; Flaxman, Abraham D; Praveen, Devarsetty; Tallo, Veronica; Joshi, Rohina; Sanvictores, Diozele; Stewart, Andrea; Mooney, Meghan D; Murray, Christopher J L; Lopez, Alan D

    2016-01-01

    We believe that it is important that governments understand the reliability of the mortality data which they have at their disposable to guide policy debates. In many instances, verbal autopsy (VA) will be the only source of mortality data for populations, yet little is known about how the accuracy of VA diagnoses is affected by the reliability of the symptom responses. We previously described the effect of the duration of time between death and VA administration on VA validity. In this paper, using the same dataset, we assess the relationship between the reliability and completeness of symptom responses and the reliability and accuracy of cause of death (COD) prediction. The study was based on VAs in the Population Health Metrics Research Consortium (PHMRC) VA Validation Dataset from study sites in Bohol and Manila, Philippines and Andhra Pradesh, India. The initial interview was repeated within 3-52 months of death. Question responses were assessed for reliability and completeness between the two survey rounds. COD was predicted by Tariff Method. A sample of 4226 VAs was collected for 2113 decedents, including 1394 adults, 349 children, and 370 neonates. Mean question reliability was unexpectedly low ( kappa  = 0.447): 42.5 % of responses positive at the first interview were negative at the second, and 47.9 % of responses positive at the second had been negative at the first. Question reliability was greater for the short form of the PHMRC instrument ( kappa  = 0.497) and when analyzed at the level of the individual decedent ( kappa  = 0.610). Reliability at the level of the individual decedent was associated with COD predictive reliability and predictive accuracy. Families give coherent accounts of events leading to death but the details vary from interview to interview for the same case. Accounts are accurate but inconsistent; different subsets of symptoms are identified on each occasion. However, there are sufficient accurate and consistent

  10. Impact of Glucose Measurement Processing Delays on Clinical Accuracy and Relevance

    PubMed Central

    Jangam, Sujit R.; Hayter, Gary; Dunn, Timothy C.

    2013-01-01

    Background In a hospital setting, glucose is often measured from venous blood in the clinical laboratory. However, laboratory glucose measurements are typically not available in real time. In practice, turn-around times for laboratory measurements can be minutes to hours. This analysis assesses the impact of turn-around time on the effective clinical accuracy of laboratory measurements. Methods Data obtained from an earlier study with 58 subjects with type 1 diabetes mellitus (T1DM) were used for this analysis. In the study, glucose measurements using a YSI glucose analyzer were obtained from venous blood samples every 15 min while the subjects were at the health care facility. To simulate delayed laboratory results, each YSI glucose value from a subject was paired with one from a later time point (from the same subject) separated by 15, 30, 45, and 60 min. To assess the clinical accuracy of a delayed YSI result relative to a real-time result, the percentage of YSI pairs that meet the International Organization for Standardization (ISO) 15197:2003(E) standard for glucose measurement accuracy (±15 mg/dl for blood glucose < 75 mg/dl, ±20% for blood glucose ≥ 75 mg/dl) was calculated. Results It was observed that delays of 15 min or more reduce clinical accuracy below the ISO 15197:2003(E) recommendation of 95%. The accuracy was less than 65% for delays of 60 min. Conclusion This analysis suggests that processing delays in glucose measurements reduce the clinical relevance of results in patients with T1DM and may similarly degrade the clinical value of measurements in other patient populations. PMID:23759399

  11. Impact of glucose measurement processing delays on clinical accuracy and relevance.

    PubMed

    Jangam, Sujit R; Hayter, Gary; Dunn, Timothy C

    2013-05-01

    In a hospital setting, glucose is often measured from venous blood in the clinical laboratory. However, laboratory glucose measurements are typically not available in real time. In practice, turn-around times for laboratory measurements can be minutes to hours. This analysis assesses the impact of turn-around time on the effective clinical accuracy of laboratory measurements. Data obtained from an earlier study with 58 subjects with type 1 diabetes mellitus (T1DM) were used for this analysis. In the study, glucose measurements using a YSI glucose analyzer were obtained from venous blood samples every 15 min while the subjects were at the health care facility. To simulate delayed laboratory results, each YSI glucose value from a subject was paired with one from a later time point (from the same subject) separated by 15, 30, 45, and 60 min. To assess the clinical accuracy of a delayed YSI result relative to a real-time result, the percentage of YSI pairs that meet the International Organization for Standardization (ISO) 15197:2003(E) standard for glucose measurement accuracy (±15 mg/dl for blood glucose < 75 mg/dl, ±20% for blood glucose ≥ 75 mg/dl) was calculated. It was observed that delays of 15 min or more reduce clinical accuracy below the ISO 15197:2003(E) recommendation of 95%. The accuracy was less than 65% for delays of 60 min. This analysis suggests that processing delays in glucose measurements reduce the clinical relevance of results in patients with T1DM and may similarly degrade the clinical value of measurements in other patient populations. © 2013 Diabetes Technology Society.

  12. Effect of education on listening comprehension of sentences on healthy elderly: analysis of number of correct responses and task execution time.

    PubMed

    Silagi, Marcela Lima; Rabelo, Camila Maia; Schochat, Eliane; Mansur, Letícia Lessa

    2017-11-13

    To analyze the effect of education on sentence listening comprehension on cognitively healthy elderly. A total of 111 healthy elderly, aged 60-80 years of both genders were divided into two groups according to educational level: low education (0-8 years of formal education) and high education (≥9 years of formal education). The participants were assessed using the Revised Token Test, an instrument that supports the evaluation of auditory comprehension of orders with different working memory and syntactic complexity demands. The indicators used for performance analysis were the number of correct responses (accuracy analysis) and task execution time (temporal analysis) in the different blocks. The low educated group had a lower number of correct responses than the high educated group on all blocks of the test. In the temporal analysis, participants with low education had longer execution time for commands on the first four blocks related to working memory. However, the two groups had similar execution time for blocks more related to syntactic comprehension. Education influenced sentence listening comprehension on elderly. Temporal analysis allowed to infer over the relationship between comprehension and other cognitive abilities, and to observe that the low educated elderly did not use effective compensation strategies to improve their performances on the task. Therefore, low educational level, associated with aging, may potentialize the risks for language decline.

  13. 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... disclosed in part shall be marked or annotated to show the amount of information deleted unless doing so...

  14. 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... complete the request. If the extension is for more than 10 working days, the Board shall provide the...

  15. 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... complete the request. If the extension is for more than 10 working days, the Board shall provide the...

  16. 10 CFR 1303.107 - Timing of responses to requests.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 4 2012-01-01 2012-01-01 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... complete the request. If the extension is for more than 10 working days, the Board shall provide the...

  17. 10 CFR 1303.107 - Timing of responses to requests.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 4 2011-01-01 2011-01-01 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... complete the request. If the extension is for more than 10 working days, the Board shall provide the...

  18. 10 CFR 1303.107 - Timing of responses to requests.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 10 Energy 4 2013-01-01 2013-01-01 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... complete the request. If the extension is for more than 10 working days, the Board shall provide the...

  19. Multiscale site-response mapping: A case study of Parkfield, California

    USGS Publications Warehouse

    Thompson, E.M.; Baise, L.G.; Kayen, R.E.; Morgan, E.C.; Kaklamanos, J.

    2011-01-01

    The scale of previously proposed methods for mapping site-response ranges from global coverage down to individual urban regions. Typically, spatial coverage and accuracy are inversely related.We use the densely spaced strong-motion stations in Parkfield, California, to estimate the accuracy of different site-response mapping methods and demonstrate a method for integrating multiple site-response estimates from the site to the global scale. This method is simply a weighted mean of a suite of different estimates, where the weights are the inverse of the variance of the individual estimates. Thus, the dominant site-response model varies in space as a function of the accuracy of the different models. For mapping applications, site-response models should be judged in terms of both spatial coverage and the degree of correlation with observed amplifications. Performance varies with period, but in general the Parkfield data show that: (1) where a velocity profile is available, the square-rootof- impedance (SRI) method outperforms the measured VS30 (30 m divided by the S-wave travel time to 30 m depth) and (2) where velocity profiles are unavailable, the topographic slope method outperforms surficial geology for short periods, but geology outperforms slope at longer periods. We develop new equations to estimate site response from topographic slope, derived from the Next Generation Attenuation (NGA) database.

  20. Simple real-time computerized tasks for detection of malingering among murderers with schizophrenia.

    PubMed

    Kertzman, Semion; Grinspan, Haim; Birger, Moshe; Shliapnikov, Nina; Alish, Yakov; Ben Nahum, Zeev; Mester, Roberto; Kotler, Moshe

    2006-01-01

    It is our contention that computer-based two-alternative forced choice techniques can be useful tools for the detection of patients with schizophrenia who feign acute psychotic symptoms and cognitive impairment as opposed to patients with schizophrenia with a true active psychosis. In our experiment, Visual Simple and Choice Reaction Time tasks were used. Reaction time in milliseconds was recorded and accuracy rate was obtained for all subjects' responses. Both types of task were administered to 27 patients with schizophrenia suspected of having committed murder. Patients with schizophrenia who were clinically assessed as malingerers achieved significantly fewer correct results, were significantly slower and less consistent in their reaction time. Congruence of performance between the Simple and Choice tasks was an additional parameter for the accurate diagnosis of malingering. The four parameters of both tests (accuracy of response, reaction time, standard deviation of reaction time and task congruency) are simple and constitute a user-friendly means for the detection of malingering in forensic practice. Another advantage of this procedure is that the software automatically measures and evaluates all the parameters.

  1. The construction of high-accuracy schemes for acoustic equations

    NASA Technical Reports Server (NTRS)

    Tang, Lei; Baeder, James D.

    1995-01-01

    An accuracy analysis of various high order schemes is performed from an interpolation point of view. The analysis indicates that classical high order finite difference schemes, which use polynomial interpolation, hold high accuracy only at nodes and are therefore not suitable for time-dependent problems. Thus, some schemes improve their numerical accuracy within grid cells by the near-minimax approximation method, but their practical significance is degraded by maintaining the same stencil as classical schemes. One-step methods in space discretization, which use piecewise polynomial interpolation and involve data at only two points, can generate a uniform accuracy over the whole grid cell and avoid spurious roots. As a result, they are more accurate and efficient than multistep methods. In particular, the Cubic-Interpolated Psuedoparticle (CIP) scheme is recommended for computational acoustics.

  2. 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.

  3. 49 CFR 234.103 - Timely response to report of malfunction.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Timely response to report of malfunction. 234.103 Section 234.103 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION GRADE CROSSING SIGNAL SYSTEM SAFETY AND STATE ACTION PLANS Response...

  4. 49 CFR 234.103 - Timely response to report of malfunction.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Timely response to report of malfunction. 234.103 Section 234.103 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION GRADE CROSSING SIGNAL SYSTEM SAFETY AND STATE ACTION PLANS Response...

  5. Attention: Reaction Time and Accuracy Reveal Different Mechanisms

    ERIC Educational Resources Information Center

    Prinzmetal, William; McCool, Christin; Park, Samuel

    2005-01-01

    The authors propose that there are 2 different mechanisms whereby spatial cues capture attention. The voluntary mechanism is the strategic allocation of perceptual resources to the location most likely to contain the target. The involuntary mechanism is a reflexive orienting response that occurs even when the spatial cue does not indicate the…

  6. 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.

  7. Assessing the speed--accuracy trade-off effect on the capacity of information processing.

    PubMed

    Donkin, Chris; Little, Daniel R; Houpt, Joseph W

    2014-06-01

    The ability to trade accuracy for speed is fundamental to human decision making. The speed-accuracy trade-off (SAT) effect has received decades of study, and is well understood in relatively simple decisions: collecting more evidence before making a decision allows one to be more accurate but also slower. The SAT in more complex paradigms has been given less attention, largely due to limits in the models and statistics that can be applied to such tasks. Here, we have conducted the first analysis of the SAT in multiple signal processing, using recently developed technologies for measuring capacity that take into account both response time and choice probability. We show that the primary influence of caution in our redundant-target experiments is on the threshold amount of evidence required to trigger a response. However, in a departure from the usual SAT effect, we found that participants strategically ignored redundant information when they were forced to respond quickly, but only when the additional stimulus was reliably redundant. Interestingly, because the capacity of the system was severely limited on redundant-target trials, ignoring additional targets meant that processing was more efficient when making fast decisions than when making slow and accurate decisions, where participants' limited resources had to be divided between the 2 stimuli. PsycINFO Database Record (c) 2014 APA, all rights reserved.

  8. Rise time and response measurements on a LiSOCl2 cell

    NASA Technical Reports Server (NTRS)

    Bastien, Caroline; Lecomte, Eric J.

    1992-01-01

    Dynamic impedance tests were performed on a 180 Ah LiSOCl2 cell in the frame of a short term work contract awarded by Aerospatiale as part of the Hermes Space Plane development work. These tests consisted of rise time and response measurements. The rise time test was performed to show the ability to deliver 4 KW, in the nominal voltage range (75-115 V), within less than 100 microseconds, and after a period at rest of 13 days. The response measurements test consisted of step response and frequency response tests. The frequency response test was performed to characterize the response of the LiSOCl2 cell to a positive or negative load step of 10 A starting from various currents. The test was performed for various depths of discharge and various temperatures. The test results were used to build a mathematical, electrical model of the LiSOCl2 cell which are also presented. The test description, test results, electrical modelization description, and conclusions are presented.

  9. 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.

  10. Diagnostic Accuracy and Turnaround Time of the Xpert MTB/RIF Assay in Routine Clinical Practice

    PubMed Central

    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. PMID:24204834

  11. Familiar Tonal Context Improves Accuracy of Pitch Interval Perception.

    PubMed

    Graves, Jackson E; Oxenham, Andrew J

    2017-01-01

    A fundamental feature of everyday music perception is sensitivity to familiar tonal structures such as musical keys. Many studies have suggested that a tonal context can enhance the perception and representation of pitch. Most of these studies have measured response time, which may reflect expectancy as opposed to perceptual accuracy. We instead used a performance-based measure, comparing participants' ability to discriminate between a "small, in-tune" interval and a "large, mistuned" interval in conditions that involved familiar tonal relations (diatonic, or major, scale notes), unfamiliar tonal relations (whole-tone or mistuned-diatonic scale notes), repetition of a single pitch, or no tonal context. The context was established with a brief sequence of tones in Experiment 1 (melodic context), and a cadence-like two-chord progression in Experiment 2 (harmonic context). In both experiments, performance significantly differed across the context conditions, with a diatonic context providing a significant advantage over no context; however, no correlation with years of musical training was observed. The diatonic tonal context also provided an advantage over the whole-tone scale context condition in Experiment 1 (melodic context), and over the mistuned scale or repetition context conditions in Experiment 2 (harmonic context). However, the relatively small benefit to performance suggests that the main advantage of tonal context may be priming of expected stimuli, rather than enhanced accuracy of pitch interval representation.

  12. 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.

  13. Reliability and accuracy of Crystaleye spectrophotometric system.

    PubMed

    Chen, Li; Tan, Jian Guo; Zhou, Jian Feng; Yang, Xu; Du, Yang; Wang, Fang Ping

    2010-01-01

    to develop an in vitro shade-measuring model to evaluate the reliability and accuracy of the Crystaleye spectrophotometric system, a newly developed spectrophotometer. four shade guides, VITA Classical, VITA 3D-Master, Chromascop and Vintage Halo NCC, were measured with the Crystaleye spectrophotometer in a standardised model, ten times for 107 shade tabs. The shade-matching results and the CIE L*a*b* values of the cervical, body and incisal regions for each measurement were automatically analysed using the supporting software. Reliability and accuracy were calculated for each shade tab both in percentage and in colour difference (ΔE). Difference was analysed by one-way ANOVA in the cervical, body and incisal regions. range of reliability was 88.81% to 98.97% and 0.13 to 0.24 ΔE units, and that of accuracy was 44.05% to 91.25% and 1.03 to 1.89 ΔE units. Significant differences in reliability and accuracy were found between the body region and the cervical and incisal regions. Comparisons made among regions and shade guides revealed that evaluation in ΔE was prone to disclose the differences. measurements with the Crystaleye spectrophotometer had similar, high reliability in different shade guides and regions, indicating predictable repeated measurements. Accuracy in the body region was high and less variable compared with the cervical and incisal regions.

  14. Rational calculation accuracy in acousto-optical matrix-vector processor

    NASA Astrophysics Data System (ADS)

    Oparin, V. V.; Tigin, Dmitry V.

    1994-01-01

    The high speed of parallel computations for a comparatively small-size processor and acceptable power consumption makes the usage of acousto-optic matrix-vector multiplier (AOMVM) attractive for processing of large amounts of information in real time. The limited accuracy of computations is an essential disadvantage of such a processor. The reduced accuracy requirements allow for considerable simplification of the AOMVM architecture and the reduction of the demands on its components.

  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. Gains in accuracy from averaging ratings of abnormality

    NASA Astrophysics Data System (ADS)

    Swensson, Richard G.; King, Jill L.; Gur, David; Good, Walter F.

    1999-05-01

    Six radiologists used continuous scales to rate 529 chest-film cases for likelihood of five separate types of abnormalities (interstitial disease, nodules, pneumothorax, alveolar infiltrates and rib fractures) in each of six replicated readings, yielding 36 separate ratings of each case for the five abnormalities. Analyses for each type of abnormality estimated the relative gains in accuracy (area below the ROC curve) obtained by averaging the case-ratings across: (1) six independent replications by each reader (30% gain), (2) six different readers within each replication (39% gain) or (3) all 36 readings (58% gain). Although accuracy differed among both readers and abnormalities, ROC curves for the median ratings showed similar relative gains in accuracy. From a latent-variable model for these gains, we estimate that about 51% of a reader's total decision variance consisted of random (within-reader) errors that were uncorrelated between replications, another 14% came from that reader's consistent (but idiosyncratic) responses to different cases, and only about 35% could be attributed to systematic variations among the sampled cases that were consistent across different readers.

  17. Effects of autocorrelation upon LANDSAT classification accuracy. [Richmond, Virginia and Denver, Colorado

    NASA Technical Reports Server (NTRS)

    Craig, R. G. (Principal Investigator)

    1983-01-01

    Richmond, Virginia and Denver, Colorado were study sites in an effort to determine the effect of autocorrelation on the accuracy of a parallelopiped classifier of LANDSAT digital data. The autocorrelation was assumed to decay to insignificant levels when sampled at distances of at least ten pixels. Spectral themes developed using blocks of adjacent pixels, and using groups of pixels spaced at least 10 pixels apart were used. Effects of geometric distortions were minimized by using only pixels from the interiors of land cover sections. Accuracy was evaluated for three classes; agriculture, residential and "all other"; both type 1 and type 2 errors were evaluated by means of overall classification accuracy. All classes give comparable results. Accuracy is approximately the same in both techniques; however, the variance in accuracy is significantly higher using the themes developed from autocorrelated data. The vectors of mean spectral response were nearly identical regardless of sampling method used. The estimated variances were much larger when using autocorrelated pixels.

  18. 48 CFR 5.203 - Publicizing and response time.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... development if the proposed contract action is expected to exceed the simplified acquisition threshold. (f) Nothing in this subpart prohibits officers or employees of agencies from responding to requests for... response times specified in paragraphs (a) through (d) of this section. Upon learning that a particular...

  19. SU-E-I-88: The Effect of System Dead Time On Real-Time Plastic and GOS Based Fiber-Optic Dosimetry Systems

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hoerner, M; Hintenlang, D

    Purpose: A methodology is presented to correct for measurement inaccuracies at high detector count rates using a plastic and GOS scintillation fibers coupled to a photomultiplier tube with digital readout. This system allows temporal acquisition and manipulation of measured data. Methods: The detection system used was a plastic scintillator and a separate gadolinium scintillator, both (0.5 diameter) coupled to an optical fiber with a Hamamatsu photon counter with a built-in microcontroller and digital interface. Count rate performance of the system was evaluated using the nonparalzable detector model. Detector response was investigated across multiple radiation sources including: orthovoltage x-ray system, colbat-60more » gamma rays, proton therapy beam, and a diagnostic radiography x-ray tube. The dead time parameter was calculated by measuring the count rate of the system at different exposure rates using a reference detector. Results: The system dead time was evaluated for the following sources of radiation used clinically: diagnostic energy x-rays, cobalt-60 gamma rays, orthovoltage xrays, particle proton accelerator, and megavoltage x-rays. It was found that dead time increased significantly when exposing the detector to sources capable of generating Cerenkov radiation, all of the sources sans the diagnostic x-rays, with increasing prominence at higher photon energies. Percent depth dose curves generated by a dedicated ionization chamber and compared to the detection system demonstrated that correcting for dead time improves accuracy. On most sources, nonparalzable model fit provided an improved system response. Conclusion: Overall, the system dead time was variable across the investigated radiation particles and energies. It was demonstrated that the system response accuracy was greatly improved by correcting for dead time effects. Cerenkov radiation plays a significant role in the increase in the system dead time through transient absorption effects

  20. Searching for serial refreshing in working memory: Using response times to track the content of the focus of attention over time.

    PubMed

    Vergauwe, Evie; Hardman, Kyle O; Rouder, Jeffrey N; Roemer, Emily; McAllaster, Sara; Cowan, Nelson

    2016-12-01

    One popular idea is that, to support the maintenance of a set of elements over brief periods of time, the focus of attention rotates among the different elements, thereby serially refreshing the content of working memory (WM). In the research reported here, probe letters were presented between to-be-remembered letters, and response times to these probes were used to infer the status of the different items in WM. If the focus of attention cycles from one item to the next, its content should be different at different points in time, and this should be reflected in a change in the response time patterns over time. Across a set of four experiments, we demonstrated a striking pattern of invariance in the response time patterns over time, suggesting either that the content of the focus of attention did not change over time or that response times cannot be used to infer the content of the focus of attention. We discuss how this pattern constrains models of WM, attention, and human information processing.