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Sample records for interv urmas maranik

  1. Interval Training.

    ERIC Educational Resources Information Center

    President's Council on Physical Fitness and Sports, Washington, DC.

    Regardless of the type of physical activity used, interval training is simply repeated periods of physical stress interspersed with recovery periods during which activity of a reduced intensity is performed. During the recovery periods, the individual usually keeps moving and does not completely recover before the next exercise interval (e.g.,…

  2. Magmatism and formation conditions of the Urma helvite-bertrandite deposit, West Transbaikal berillium province

    NASA Astrophysics Data System (ADS)

    Lykhin, D. A.; Yarmolyuk, V. V.

    2014-07-01

    The relationships between mineralization and magmatism during the formation of the Early Mesozoic West Transbaikal beryllium province are exemplified in the Urma helvite-bertrandite deposit. The deposit is drawn toward granitoids of elevated alkalinity, which belong to the Tashir Complex. Mineralization is related to leucogranite and characterized by patched distribution controlled by localization of metasomatic alteration. The latter is identified owing to replacement of feldspar with microcline and albite followed by silicification related to fracture zones. Helvite and bertrandite are the major Be minerals at the deposit. The Be grade of the ore is nonuniform and varies from 740 to 25000 ppm. Zircon, malacon, monazite, allanite, bastnaesite, columbite, and xenotime occur in metasomatic rocks together with Be minerals. Geochemical characteristics of alkali granites and metasomatic rocks are similar in a wide range of incompatible elements. Both are characterized by lowered Ba, Sr, P, and Eu contents and enriched in Th, U, Pb, Zr, and Hf. The degree of enrichment is the highest in the ore. The Be content in the ore correlates with concentrations of a number of other rare metals typical of host granite, which form their own mineralization against the background of metasomatic alteration, including Zr and REE minerals. Similarity in geochemistry of granitic rocks and Be ore indicates that the Urma deposit was related to the evolution of magmatic melt. Regional correlation shows that the ore-magmatic system of the Urma deposit is close to that of the Orot deposit, one of the largest in the central segment of the West Transbaikal metallogenic province. Both deposits are characterized by a similar composition of granitoids and comparable localization of ore zones in the structure of plutons. This similarity supports the high ore resource potential of Early Mesozoic alkali granites in the western Transbaikal region. Taking into account that these granitoids are

  3. Interval neural networks

    SciTech Connect

    Patil, R.B.

    1995-05-01

    Traditional neural networks like multi-layered perceptrons (MLP) use example patterns, i.e., pairs of real-valued observation vectors, ({rvec x},{rvec y}), to approximate function {cflx f}({rvec x}) = {rvec y}. To determine the parameters of the approximation, a special version of the gradient descent method called back-propagation is widely used. In many situations, observations of the input and output variables are not precise; instead, we usually have intervals of possible values. The imprecision could be due to the limited accuracy of the measuring instrument or could reflect genuine uncertainty in the observed variables. In such situation input and output data consist of mixed data types; intervals and precise numbers. Function approximation in interval domains is considered in this paper. We discuss a modification of the classical backpropagation learning algorithm to interval domains. Results are presented with simple examples demonstrating few properties of nonlinear interval mapping as noise resistance and finding set of solutions to the function approximation problem.

  4. Interval arithmetic operations for uncertainty analysis with correlated interval variables

    NASA Astrophysics Data System (ADS)

    Jiang, Chao; Fu, Chun-Ming; Ni, Bing-Yu; Han, Xu

    2016-08-01

    A new interval arithmetic method is proposed to solve interval functions with correlated intervals through which the overestimation problem existing in interval analysis could be significantly alleviated. The correlation between interval parameters is defined by the multidimensional parallelepiped model which is convenient to describe the correlative and independent interval variables in a unified framework. The original interval variables with correlation are transformed into the standard space without correlation, and then the relationship between the original variables and the standard interval variables is obtained. The expressions of four basic interval arithmetic operations, namely addition, subtraction, multiplication, and division, are given in the standard space. Finally, several numerical examples and a two-step bar are used to demonstrate the effectiveness of the proposed method.

  5. Multichannel interval timer (MINT)

    SciTech Connect

    Kimball, K.B.

    1982-06-01

    A prototype Multichannel INterval Timer (MINT) has been built for measuring signal Time of Arrival (TOA) from sensors placed in blast environments. The MINT is intended to reduce the space, equipment costs, and data reduction efforts associated with traditional analog TOA recording methods, making it more practical to field the large arrays of TOA sensors required to characterize blast environments. This document describes the MINT design features, provides the information required for installing and operating the system, and presents proposed improvements for the next generation system.

  6. Interval-valued random functions and the kriging of intervals

    SciTech Connect

    Diamond, P.

    1988-04-01

    Estimation procedures using data that include some values known to lie within certain intervals are usually regarded as problems of constrained optimization. A different approach is used here. Intervals are treated as elements of a positive cone, obeying the arithmetic of interval analysis, and positive interval-valued random functions are discussed. A kriging formalism for interval-valued data is developed. It provides estimates that are themselves intervals. In this context, the condition that kriging weights be positive is seen to arise in a natural way. A numerical example is given, and the extension to universal kriging is sketched.

  7. An interval model updating strategy using interval response surface models

    NASA Astrophysics Data System (ADS)

    Fang, Sheng-En; Zhang, Qiu-Hu; Ren, Wei-Xin

    2015-08-01

    Stochastic model updating provides an effective way of handling uncertainties existing in real-world structures. In general, probabilistic theories, fuzzy mathematics or interval analyses are involved in the solution of inverse problems. However in practice, probability distributions or membership functions of structural parameters are often unavailable due to insufficient information of a structure. At this moment an interval model updating procedure shows its superiority in the aspect of problem simplification since only the upper and lower bounds of parameters and responses are sought. To this end, this study develops a new concept of interval response surface models for the purpose of efficiently implementing the interval model updating procedure. The frequent interval overestimation due to the use of interval arithmetic can be maximally avoided leading to accurate estimation of parameter intervals. Meanwhile, the establishment of an interval inverse problem is highly simplified, accompanied by a saving of computational costs. By this means a relatively simple and cost-efficient interval updating process can be achieved. Lastly, the feasibility and reliability of the developed method have been verified against a numerical mass-spring system and also against a set of experimentally tested steel plates.

  8. Minimax confidence intervals in geomagnetism

    NASA Technical Reports Server (NTRS)

    Stark, Philip B.

    1992-01-01

    The present paper uses theory of Donoho (1989) to find lower bounds on the lengths of optimally short fixed-length confidence intervals (minimax confidence intervals) for Gauss coefficients of the field of degree 1-12 using the heat flow constraint. The bounds on optimal minimax intervals are about 40 percent shorter than Backus' intervals: no procedure for producing fixed-length confidence intervals, linear or nonlinear, can give intervals shorter than about 60 percent the length of Backus' in this problem. While both methods rigorously account for the fact that core field models are infinite-dimensional, the application of the techniques to the geomagnetic problem involves approximations and counterfactual assumptions about the data errors, and so these results are likely to be extremely optimistic estimates of the actual uncertainty in Gauss coefficients.

  9. Effect Sizes, Confidence Intervals, and Confidence Intervals for Effect Sizes

    ERIC Educational Resources Information Center

    Thompson, Bruce

    2007-01-01

    The present article provides a primer on (a) effect sizes, (b) confidence intervals, and (c) confidence intervals for effect sizes. Additionally, various admonitions for reformed statistical practice are presented. For example, a very important implication of the realization that there are dozens of effect size statistics is that "authors must…

  10. Explorations in Statistics: Confidence Intervals

    ERIC Educational Resources Information Center

    Curran-Everett, Douglas

    2009-01-01

    Learning about statistics is a lot like learning about science: the learning is more meaningful if you can actively explore. This third installment of "Explorations in Statistics" investigates confidence intervals. A confidence interval is a range that we expect, with some level of confidence, to include the true value of a population parameter…

  11. Teaching Confidence Intervals Using Simulation

    ERIC Educational Resources Information Center

    Hagtvedt, Reidar; Jones, Gregory Todd; Jones, Kari

    2008-01-01

    Confidence intervals are difficult to teach, in part because most students appear to believe they understand how to interpret them intuitively. They rarely do. To help them abandon their misconception and achieve understanding, we have developed a simulation tool that encourages experimentation with multiple confidence intervals derived from the…

  12. Automatic Error Analysis Using Intervals

    ERIC Educational Resources Information Center

    Rothwell, E. J.; Cloud, M. J.

    2012-01-01

    A technique for automatic error analysis using interval mathematics is introduced. A comparison to standard error propagation methods shows that in cases involving complicated formulas, the interval approach gives comparable error estimates with much less effort. Several examples are considered, and numerical errors are computed using the INTLAB…

  13. VARIABLE TIME-INTERVAL GENERATOR

    DOEpatents

    Gross, J.E.

    1959-10-31

    This patent relates to a pulse generator and more particularly to a time interval generator wherein the time interval between pulses is precisely determined. The variable time generator comprises two oscillators with one having a variable frequency output and the other a fixed frequency output. A frequency divider is connected to the variable oscillator for dividing its frequency by a selected factor and a counter is used for counting the periods of the fixed oscillator occurring during a cycle of the divided frequency of the variable oscillator. This defines the period of the variable oscillator in terms of that of the fixed oscillator. A circuit is provided for selecting as a time interval a predetermined number of periods of the variable oscillator. The output of the generator consists of a first pulse produced by a trigger circuit at the start of the time interval and a second pulse marking the end of the time interval produced by the same trigger circuit.

  14. Subjective probability intervals: how to reduce overconfidence by interval evaluation.

    PubMed

    Winman, Anders; Hansson, Patrik; Juslin, Peter

    2004-11-01

    Format dependence implies that assessment of the same subjective probability distribution produces different conclusions about over- or underconfidence depending on the assessment format. In 2 experiments, the authors demonstrate that the overconfidence bias that occurs when participants produce intervals for an uncertain quantity is almost abolished when they evaluate the probability that the same intervals include the quantity. The authors successfully apply a method for adaptive adjustment of probability intervals as a debiasing tool and discuss a tentative explanation in terms of a naive sampling model. According to this view, people report their experiences accurately, but they are naive in that they treat both sample proportion and sample dispersion as unbiased estimators, yielding small bias in probability evaluation but strong bias in interval production. PMID:15521796

  15. TIME-INTERVAL MEASURING DEVICE

    DOEpatents

    Gross, J.E.

    1958-04-15

    An electronic device for measuring the time interval between two control pulses is presented. The device incorporates part of a previous approach for time measurement, in that pulses from a constant-frequency oscillator are counted during the interval between the control pulses. To reduce the possible error in counting caused by the operation of the counter gating circuit at various points in the pulse cycle, the described device provides means for successively delaying the pulses for a fraction of the pulse period so that a final delay of one period is obtained and means for counting the pulses before and after each stage of delay during the time interval whereby a plurality of totals is obtained which may be averaged and multplied by the pulse period to obtain an accurate time- Interval measurement.

  16. Simple Interval Timers for Microcomputers.

    ERIC Educational Resources Information Center

    McInerney, M.; Burgess, G.

    1985-01-01

    Discusses simple interval timers for microcomputers, including (1) the Jiffy clock; (2) CPU count timers; (3) screen count timers; (4) light pen timers; and (5) chip timers. Also examines some of the general characteristics of all types of timers. (JN)

  17. Subjective Probability Intervals: How to Reduce Overconfidence by Interval Evaluation

    ERIC Educational Resources Information Center

    Winman, Anders; Hansson, Patrik; Juslin, Peter

    2004-01-01

    Format dependence implies that assessment of the same subjective probability distribution produces different conclusions about over- or underconfidence depending on the assessment format. In 2 experiments, the authors demonstrate that the overconfidence bias that occurs when participants produce intervals for an uncertain quantity is almost…

  18. Generalized Confidence Intervals and Fiducial Intervals for Some Epidemiological Measures

    PubMed Central

    Bebu, Ionut; Luta, George; Mathew, Thomas; Agan, Brian K.

    2016-01-01

    For binary outcome data from epidemiological studies, this article investigates the interval estimation of several measures of interest in the absence or presence of categorical covariates. When covariates are present, the logistic regression model as well as the log-binomial model are investigated. The measures considered include the common odds ratio (OR) from several studies, the number needed to treat (NNT), and the prevalence ratio. For each parameter, confidence intervals are constructed using the concepts of generalized pivotal quantities and fiducial quantities. Numerical results show that the confidence intervals so obtained exhibit satisfactory performance in terms of maintaining the coverage probabilities even when the sample sizes are not large. An appealing feature of the proposed solutions is that they are not based on maximization of the likelihood, and hence are free from convergence issues associated with the numerical calculation of the maximum likelihood estimators, especially in the context of the log-binomial model. The results are illustrated with a number of examples. The overall conclusion is that the proposed methodologies based on generalized pivotal quantities and fiducial quantities provide an accurate and unified approach for the interval estimation of the various epidemiological measures in the context of binary outcome data with or without covariates. PMID:27322305

  19. High resolution time interval meter

    DOEpatents

    Martin, A.D.

    1986-05-09

    Method and apparatus are provided for measuring the time interval between two events to a higher resolution than reliability available from conventional circuits and component. An internal clock pulse is provided at a frequency compatible with conventional component operating frequencies for reliable operation. Lumped constant delay circuits are provided for generating outputs at delay intervals corresponding to the desired high resolution. An initiation START pulse is input to generate first high resolution data. A termination STOP pulse is input to generate second high resolution data. Internal counters count at the low frequency internal clock pulse rate between the START and STOP pulses. The first and second high resolution data are logically combined to directly provide high resolution data to one counter and correct the count in the low resolution counter to obtain a high resolution time interval measurement.

  20. Updating representations of temporal intervals.

    PubMed

    Danckert, James; Anderson, Britt

    2015-12-01

    Effectively engaging with the world depends on accurate representations of the regularities that make up that world-what we call mental models. The success of any mental model depends on the ability to adapt to changes-to 'update' the model. In prior work, we have shown that damage to the right hemisphere of the brain impairs the ability to update mental models across a range of tasks. Given the disparate nature of the tasks we have employed in this prior work (i.e. statistical learning, language acquisition, position priming, perceptual ambiguity, strategic game play), we propose that a cognitive module important for updating mental representations should be generic, in the sense that it is invoked across multiple cognitive and perceptual domains. To date, the majority of our tasks have been visual in nature. Given the ubiquity and import of temporal information in sensory experience, we examined the ability to build and update mental models of time. We had healthy individuals complete a temporal prediction task in which intervals were initially drawn from one temporal range before an unannounced switch to a different range of intervals. Separate groups had the second range of intervals switch to one that contained either longer or shorter intervals than the first range. Both groups showed significant positive correlations between perceptual and prediction accuracy. While each group updated mental models of temporal intervals, those exposed to shorter intervals did so more efficiently. Our results support the notion of generic capacity to update regularities in the environment-in this instance based on temporal information. The task developed here is well suited to investigations in neurological patients and in neuroimaging settings.

  1. Updating representations of temporal intervals.

    PubMed

    Danckert, James; Anderson, Britt

    2015-12-01

    Effectively engaging with the world depends on accurate representations of the regularities that make up that world-what we call mental models. The success of any mental model depends on the ability to adapt to changes-to 'update' the model. In prior work, we have shown that damage to the right hemisphere of the brain impairs the ability to update mental models across a range of tasks. Given the disparate nature of the tasks we have employed in this prior work (i.e. statistical learning, language acquisition, position priming, perceptual ambiguity, strategic game play), we propose that a cognitive module important for updating mental representations should be generic, in the sense that it is invoked across multiple cognitive and perceptual domains. To date, the majority of our tasks have been visual in nature. Given the ubiquity and import of temporal information in sensory experience, we examined the ability to build and update mental models of time. We had healthy individuals complete a temporal prediction task in which intervals were initially drawn from one temporal range before an unannounced switch to a different range of intervals. Separate groups had the second range of intervals switch to one that contained either longer or shorter intervals than the first range. Both groups showed significant positive correlations between perceptual and prediction accuracy. While each group updated mental models of temporal intervals, those exposed to shorter intervals did so more efficiently. Our results support the notion of generic capacity to update regularities in the environment-in this instance based on temporal information. The task developed here is well suited to investigations in neurological patients and in neuroimaging settings. PMID:26303026

  2. An Event Restriction Interval Theory of Tense

    ERIC Educational Resources Information Center

    Beamer, Brandon Robert

    2012-01-01

    This dissertation presents a novel theory of tense and tense-like constructions. It is named after a key theoretical component of the theory, the event restriction interval. In Event Restriction Interval (ERI) Theory, sentences are semantically evaluated relative to an index which contains two key intervals, the evaluation interval and the event…

  3. Chaotic dynamics from interspike intervals.

    PubMed

    Pavlov, A N; Sosnovtseva, O V; Mosekilde, E; Anishchenko, V S

    2001-03-01

    Considering two different mathematical models describing chaotic spiking phenomena, namely, an integrate-and-fire and a threshold-crossing model, we discuss the problem of extracting dynamics from interspike intervals (ISIs) and show that the possibilities of computing the largest Lyapunov exponent (LE) from point processes differ between the two models. We also consider the problem of estimating the second LE and the possibility to diagnose hyperchaotic behavior by processing spike trains. Since the second exponent is quite sensitive to the structure of the ISI series, we investigate the problem of its computation. PMID:11308739

  4. Chaotic dynamics from interspike intervals

    NASA Astrophysics Data System (ADS)

    Pavlov, Alexey N.; Sosnovtseva, Olga V.; Mosekilde, Erik; Anishchenko, Vadim S.

    2001-03-01

    Considering two different mathematical models describing chaotic spiking phenomena, namely, an integrate-and-fire and a threshold-crossing model, we discuss the problem of extracting dynamics from interspike intervals (ISIs) and show that the possibilities of computing the largest Lyapunov exponent (LE) from point processes differ between the two models. We also consider the problem of estimating the second LE and the possibility to diagnose hyperchaotic behavior by processing spike trains. Since the second exponent is quite sensitive to the structure of the ISI series, we investigate the problem of its computation.

  5. High resolution time interval counter

    DOEpatents

    Condreva, Kenneth J.

    1994-01-01

    A high resolution counter circuit measures the time interval between the occurrence of an initial and a subsequent electrical pulse to two nanoseconds resolution using an eight megahertz clock. The circuit includes a main counter for receiving electrical pulses and generating a binary word--a measure of the number of eight megahertz clock pulses occurring between the signals. A pair of first and second pulse stretchers receive the signal and generate a pair of output signals whose widths are approximately sixty-four times the time between the receipt of the signals by the respective pulse stretchers and the receipt by the respective pulse stretchers of a second subsequent clock pulse. Output signals are thereafter supplied to a pair of start and stop counters operable to generate a pair of binary output words representative of the measure of the width of the pulses to a resolution of two nanoseconds. Errors associated with the pulse stretchers are corrected by providing calibration data to both stretcher circuits, and recording start and stop counter values. Stretched initial and subsequent signals are combined with autocalibration data and supplied to an arithmetic logic unit to determine the time interval in nanoseconds between the pair of electrical pulses being measured.

  6. High resolution time interval counter

    DOEpatents

    Condreva, K.J.

    1994-07-26

    A high resolution counter circuit measures the time interval between the occurrence of an initial and a subsequent electrical pulse to two nanoseconds resolution using an eight megahertz clock. The circuit includes a main counter for receiving electrical pulses and generating a binary word--a measure of the number of eight megahertz clock pulses occurring between the signals. A pair of first and second pulse stretchers receive the signal and generate a pair of output signals whose widths are approximately sixty-four times the time between the receipt of the signals by the respective pulse stretchers and the receipt by the respective pulse stretchers of a second subsequent clock pulse. Output signals are thereafter supplied to a pair of start and stop counters operable to generate a pair of binary output words representative of the measure of the width of the pulses to a resolution of two nanoseconds. Errors associated with the pulse stretchers are corrected by providing calibration data to both stretcher circuits, and recording start and stop counter values. Stretched initial and subsequent signals are combined with autocalibration data and supplied to an arithmetic logic unit to determine the time interval in nanoseconds between the pair of electrical pulses being measured. 3 figs.

  7. Postexercise Hypotension After Continuous, Aerobic Interval, and Sprint Interval Exercise.

    PubMed

    Angadi, Siddhartha S; Bhammar, Dharini M; Gaesser, Glenn A

    2015-10-01

    We examined the effects of 3 exercise bouts, differing markedly in intensity, on postexercise hypotension (PEH). Eleven young adults (age: 24.6 ± 3.7 years) completed 4 randomly assigned experimental conditions: (a) control, (b) 30-minute steady-state exercise (SSE) at 75-80% maximum heart rate (HRmax), (4) aerobic interval exercise (AIE): four 4-minute bouts at 90-95% HRmax, separated by 3 minutes of active recovery, and (d) sprint interval exercise (SIE): six 30-second Wingate sprints, separated by 4 minutes of active recovery. Exercise was performed on a cycle ergometer. Blood pressure (BP) was measured before exercise and every 15-minute postexercise for 3 hours. Linear mixed models were used to compare BP between trials. During the 3-hour postexercise, systolic BP (SBP) was lower (p < 0.001) after AIE (118 ± 10 mm Hg), SSE (121 ± 10 mm Hg), and SIE (121 ± 11 mm Hg) compared with control (124 ± 8 mm Hg). Diastolic BP (DBP) was also lower (p < 0.001) after AIE (66 ± 7 mm Hg), SSE (69 ± 6 mm Hg), and SIE (68 ± 8 mm Hg) compared with control (71 ± 7 mm Hg). Only AIE resulted in sustained (>2 hours) PEH, with SBP (120 ± 9 mm Hg) and DBP (68 ± 7 mm Hg) during the third-hour postexercise being lower (p ≤ 0.05) than control (124 ± 8 and 70 ± 7 mm Hg). Although all exercise bouts produced similar reductions in BP at 1-hour postexercise, the duration of PEH was greatest after AIE.

  8. Orders on Intervals Over Partially Ordered Sets: Extending Allen's Algebra and Interval Graph Results

    SciTech Connect

    Zapata, Francisco; Kreinovich, Vladik; Joslyn, Cliff A.; Hogan, Emilie A.

    2013-08-01

    To make a decision, we need to compare the values of quantities. In many practical situations, we know the values with interval uncertainty. In such situations, we need to compare intervals. Allen’s algebra describes all possible relations between intervals on the real line, and ordering relations between such intervals are well studied. In this paper, we extend this description to intervals in an arbitrary partially ordered set (poset). In particular, we explicitly describe ordering relations between intervals that generalize relation between points. As auxiliary results, we provide a logical interpretation of the relation between intervals, and extend the results about interval graphs to intervals over posets.

  9. Pigeons' Choices between Fixed-Interval and Random-Interval Schedules: Utility of Variability?

    ERIC Educational Resources Information Center

    Andrzejewski, Matthew E.; Cardinal, Claudia D.; Field, Douglas P.; Flannery, Barbara A.; Johnson, Michael; Bailey, Kathleen; Hineline, Philip N.

    2005-01-01

    Pigeons' choosing between fixed-interval and random-interval schedules of reinforcement was investigated in three experiments using a discrete-trial procedure. In all three experiments, the random-interval schedule was generated by sampling a probability distribution at an interval (and in multiples of the interval) equal to that of the…

  10. Scaling of light and dark time intervals.

    PubMed

    Marinova, J

    1978-01-01

    Scaling of light and dark time intervals of 0.1 to 1.1 s is performed by the mehtod of magnitude estimation with respect to a given standard. The standards differ in duration and type (light and dark). The light intervals are subjectively estimated as longer than the dark ones. The relation between the mean interval estimations and their magnitude is linear for both light and dark intervals.

  11. Permutations and topological entropy for interval maps

    NASA Astrophysics Data System (ADS)

    Misiurewicz, Michal

    2003-05-01

    Recently Bandt, Keller and Pompe (2002 Entropy of interval maps via permutations Nonlinearity 15 1595-602) introduced a method of computing the entropy of piecewise monotone interval maps by counting permutations exhibited by initial pieces of orbits. We show that for topological entropy this method does not work for arbitrary continuous interval maps. We also show that for piecewise monotone interval maps topological entropy can be computed by counting permutations exhibited by periodic orbits.

  12. Interval approach to braneworld gravity

    NASA Astrophysics Data System (ADS)

    Carena, Marcela; Lykken, Joseph; Park, Minjoon

    2005-10-01

    Gravity in five-dimensional braneworld backgrounds may exhibit extra scalar degrees of freedom with problematic features, including kinetic ghosts and strong coupling behavior. Analysis of such effects is hampered by the standard heuristic approaches to braneworld gravity, which use the equations of motion as the starting point, supplemented by orbifold projections and junction conditions. Here we develop the interval approach to braneworld gravity, which begins with an action principle. This shows how to implement general covariance, despite allowing metric fluctuations that do not vanish on the boundaries. We reproduce simple Z2 orbifolds of gravity, even though in this approach we never perform a Z2 projection. We introduce a family of “straight gauges”, which are bulk coordinate systems in which both branes appear as straight slices in a single coordinate patch. Straight gauges are extremely useful for analyzing metric fluctuations in braneworld models. By explicit gauge-fixing, we show that a general AdS5/AdS4 setup with two branes has at most a radion, but no physical “brane-bending” modes.

  13. Intervals in evolutionary algorithms for global optimization

    SciTech Connect

    Patil, R.B.

    1995-05-01

    Optimization is of central concern to a number of disciplines. Interval Arithmetic methods for global optimization provide us with (guaranteed) verified results. These methods are mainly restricted to the classes of objective functions that are twice differentiable and use a simple strategy of eliminating a splitting larger regions of search space in the global optimization process. An efficient approach that combines the efficient strategy from Interval Global Optimization Methods and robustness of the Evolutionary Algorithms is proposed. In the proposed approach, search begins with randomly created interval vectors with interval widths equal to the whole domain. Before the beginning of the evolutionary process, fitness of these interval parameter vectors is defined by evaluating the objective function at the center of the initial interval vectors. In the subsequent evolutionary process the local optimization process returns an estimate of the bounds of the objective function over the interval vectors. Though these bounds may not be correct at the beginning due to large interval widths and complicated function properties, the process of reducing interval widths over time and a selection approach similar to simulated annealing helps in estimating reasonably correct bounds as the population evolves. The interval parameter vectors at these estimated bounds (local optima) are then subjected to crossover and mutation operators. This evolutionary process continues for predetermined number of generations in the search of the global optimum.

  14. The interval order polytope of a digraph

    SciTech Connect

    Mueller, R.; Schulz, A.

    1994-12-31

    Interval orders and their cocomparability graphs, the interval graphs, are of significant importance as structures of solutions for several combinatorial optimization problems. This is due to the fact that each element is associated with an interval, which may be interpreted as a time interval, for example in a schedule, or as a substring in a string of items, for example, a substring of a DNA string in molecular biology. In the talk we show that the interval order polytope of a digraph may serve as a basis for a polyhedral combinatorial approach to this class of problems. We present results on odd cycle and clique based valid inequalities and discuss the complexity of their separation problem. We show that well-known valid inequalities of the linear ordering polytope, as, e.g., Mobius ladder inequalities and fence inequalities obtain a natural interpretation in terms of these inequalities of the interval order polytope.

  15. Stimulus properties of fixed-interval responses.

    PubMed

    Buchman, I B; Zeiler, M D

    1975-11-01

    Responses in the first component of a chained schedule produced a change to the terminal component according to a fixed-interval schedule. The number of responses emitted in the fixed interval determined whether a variable-interval schedule of food presentation or extinction prevailed in the terminal component. In one condition, the variable-interval schedule was in effect only if the number of responses during the fixed interval was less than that specified; in another condition, the number of responses had to exceed that specified. The number of responses emitted in the fixed interval did not shift markedly in the direction required for food presentation. Instead, responding often tended to change in the opposite direction. Such an effect indicated that differential food presentation did not modify the reference behavior in accord with the requirement, but it was consistent with other data on fixed-interval schedule performance. Behavior in the terminal component, however, did reveal sensitivity to the relation between total responses emitted in the fixed interval and the availability of food. Response rate in the terminal component was a function of the proximity of the response number emitted in the fixed interval to that required for food presentation. Thus, response number served as a discriminative stimulus controlling subsequent performance.

  16. A note on the path interval distance.

    PubMed

    Coons, Jane Ivy; Rusinko, Joseph

    2016-06-01

    The path interval distance accounts for global congruence between locally incongruent trees. We show that the path interval distance provides a lower bound for the nearest neighbor interchange distance. In contrast to the Robinson-Foulds distance, random pairs of trees are unlikely to be maximally distant from one another under the path interval distance. These features indicate that the path interval distance should play a role in phylogenomics where the comparison of trees on a fixed set of taxa is becoming increasingly important. PMID:27040521

  17. A note on the path interval distance.

    PubMed

    Coons, Jane Ivy; Rusinko, Joseph

    2016-06-01

    The path interval distance accounts for global congruence between locally incongruent trees. We show that the path interval distance provides a lower bound for the nearest neighbor interchange distance. In contrast to the Robinson-Foulds distance, random pairs of trees are unlikely to be maximally distant from one another under the path interval distance. These features indicate that the path interval distance should play a role in phylogenomics where the comparison of trees on a fixed set of taxa is becoming increasingly important.

  18. Interval and Contour Processing in Autism

    ERIC Educational Resources Information Center

    Heaton, Pamela

    2005-01-01

    High functioning children with autism and age and intelligence matched controls participated in experiments testing perception of pitch intervals and musical contours. The finding from the interval study showed superior detection of pitch direction over small pitch distances in the autism group. On the test of contour discrimination no group…

  19. SINGLE-INTERVAL GAS PERMEABILITY ESTIMATION

    EPA Science Inventory

    Single-interval, steady-steady-state gas permeability testing requires estimation of pressure at a screened interval which in turn requires measurement of friction factors as a function of mass flow rate. Friction factors can be obtained by injecting air through a length of pipe...

  20. Interval colorectal carcinoma: An unsolved debate

    PubMed Central

    Benedict, Mark; Neto, Antonio Galvao; Zhang, Xuchen

    2015-01-01

    Colorectal carcinoma (CRC), as the third most common new cancer diagnosis, poses a significant health risk to the population. Interval CRCs are those that appear after a negative screening test or examination. The development of interval CRCs has been shown to be multifactorial: location of exam-academic institution versus community hospital, experience of the endoscopist, quality of the procedure, age of the patient, flat versus polypoid neoplasia, genetics, hereditary gastrointestinal neoplasia, and most significantly missed or incompletely excised lesions. The rate of interval CRCs has decreased in the last decade, which has been ascribed to an increased understanding of interval disease and technological advances in the screening of high risk individuals. In this article, we aim to review the literature with regard to the multifactorial nature of interval CRCs and provide the most recent developments regarding this important gastrointestinal entity. PMID:26668498

  1. Constructing Confidence Intervals for Qtl Location

    PubMed Central

    Mangin, B.; Goffinet, B.; Rebai, A.

    1994-01-01

    We describe a method for constructing the confidence interval of the QTL location parameter. This method is developed in the local asymptotic framework, leading to a linear model at each position of the putative QTL. The idea is to construct a likelihood ratio test, using statistics whose asymptotic distribution does not depend on the nuisance parameters and in particular on the effect of the QTL. We show theoretical properties of the confidence interval built with this test, and compare it with the classical confidence interval using simulations. We show in particular, that our confidence interval has the correct probability of containing the true map location of the QTL, for almost all QTLs, whereas the classical confidence interval can be very biased for QTLs having small effect. PMID:7896108

  2. Sampling Theory and Confidence Intervals for Effect Sizes: Using ESCI To Illustrate "Bouncing"; Confidence Intervals.

    ERIC Educational Resources Information Center

    Du, Yunfei

    This paper discusses the impact of sampling error on the construction of confidence intervals around effect sizes. Sampling error affects the location and precision of confidence intervals. Meta-analytic resampling demonstrates that confidence intervals can haphazardly bounce around the true population parameter. Special software with graphical…

  3. Assessing uncertainty in reference intervals via tolerance intervals: application to a mixed model describing HIV infection.

    PubMed

    Katki, Hormuzd A; Engels, Eric A; Rosenberg, Philip S

    2005-10-30

    We define the reference interval as the range between the 2.5th and 97.5th percentiles of a random variable. We use reference intervals to compare characteristics of a marker of disease progression between affected populations. We use a tolerance interval to assess uncertainty in the reference interval. Unlike the tolerance interval, the estimated reference interval does not contains the true reference interval with specified confidence (or credibility). The tolerance interval is easy to understand, communicate and visualize. We derive estimates of the reference interval and its tolerance interval for markers defined by features of a linear mixed model. Examples considered are reference intervals for time trends in HIV viral load, and CD4 per cent, in HIV-infected haemophiliac children and homosexual men. We estimate the intervals with likelihood methods and also develop a Bayesian model in which the parameters are estimated via Markov-chain Monte Carlo. The Bayesian formulation naturally overcomes some important limitations of the likelihood model. PMID:16189804

  4. Acceleration-induced electrocardiographic interval changes.

    PubMed

    Whinnery, C C; Whinnery, J E

    1988-02-01

    The electrocardiographic intervals (PR, QRS, QT, and RR) before, during, and post +Gz stress were measured in 24 healthy male subjects undergoing +Gz centrifuge exposure. The PR and QRS intervals responded in a predictable manner, shortening during stress and returning to baseline resting values post-stress. The QT interval, however, was not observed to be dependent solely on heart rate. Bazett's formula, which was developed to correct for heart rate variability, did not adequately result in a homogeneous correction of the QT interval for each stress-related period. During +Gz stress, the QT was shortened, and the QTc prolonged. The QT interval remained shortened even though the heart rate returned to baseline (with the QTc undercorrected) in the post-stress period. The QT (QTc) interval variations probably reflect the effects of both heart rate and autonomic balance during and after +Gz stress, and may provide a measure of the prevailing autonomic (sympathetic or parasympathetic) tone existing at a given point associated with +Gz stress. These electrocardiographic interval changes define the normal response for healthy individuals. Individuals with exaggerated autonomic responses could be identified by comparing their responses to these normal responses resulting from +Gz stress. PMID:3345170

  5. Interval modeling of dynamics for multibody systems

    NASA Astrophysics Data System (ADS)

    Auer, Ekaterina

    2007-02-01

    Modeling of multibody systems is an important though demanding field of application for interval arithmetic. Interval modeling of dynamics is particularly challenging, not least because of the differential equations which have to be solved in the process. Most modeling tools transform these equations into a (non-autonomous) initial value problem, interval algorithms for solving of which are known. The challenge then consists in finding interfaces between these algorithms and the modeling tools. This includes choosing between "symbolic" and "numerical" modeling environments, transforming the usually non-autonomous resulting system into an autonomous one, ensuring conformity of the new interval version to the old numerical, etc. In this paper, we focus on modeling multibody systems' dynamics with the interval extension of the "numerical" environment MOBILE, discuss the techniques which make the uniform treatment of interval and non-interval modeling easier, comment on the wrapping effect, and give reasons for our choice of MOBILE by comparing the results achieved with its help with those obtained by analogous symbolic tools.

  6. The microanalysis of fixed-interval responding

    PubMed Central

    Gentry, G. David; Weiss, Bernard; Laties, Victor G.

    1983-01-01

    The fixed-interval schedule of reinforcement is one of the more widely studied schedules in the experimental analysis of behavior and is also a common baseline for behavior pharmacology. Despite many intensive studies, the controlling variables and the pattern of behavior engendered are not well understood. The present study examined the microstructure and superstructure of the behavior engendered by a fixed-interval 5- and a fixed-interval 15-minute schedule of food reinforcement in the pigeon. Analysis of performance typical of fixed-interval responding indicated that the scalloped pattern does not result from smooth acceleration in responding, but, rather, from renewed pausing early in the interval. Individual interresponse-time (IRT) analyses provided no evidence of acceleration. There was a strong indication of alternation in shorter-longer IRTs, but these shorter-longer IRTs did not occur at random, reflecting instead a sequential dependency in successive IRTs. Furthermore, early in the interval there was a high relative frequency of short IRTs. Such a pattern of early pauses and short IRTs does not suggest behavior typical of reinforced responding as exemplified by the pattern found near the end of the interval. Thus, behavior from clearly scalloped performance can be classified into three states: postreinforcement pause, interim behavior, and terminal behavior. PMID:16812324

  7. Microanalysis of fixed-interval responding

    SciTech Connect

    Gentry, G.D.; Weiss, B.; Laties, V.G.

    1983-03-01

    The fixed-interval schedule of reinforcement is one of the more widely studied schedules in the experimental analysis of behavior and is also a common baseline for behavior pharmacology. Despite many intensive studies, the controlling variables and the pattern of behavior engendered are not well understood. The present study examined the microstructure and superstructure of the behavior engendered by a fixed-interval 5- and a fixed-interval 15-minute schedule of food reinforcement in the pigeon. Analysis of performance typical of fixed-interval responding indicated that the scalloped pattern does not result from smooth acceleration in responding, but, rather, from renewed pausing early in the interval. Individual interresponse-time (IRT) analyses provided no evidence of acceleration. There was a strong indication of alternation is shorter-longer IRTs, but these shorter-longer IRTs did not occur at random, reflecting instead a sequential dependency in successive IRTs. Furthermore, early in the interval there was a high relative frequency of short IRTs. Such a pattern of early pauses and short IRTs does not suggest behavior typical of reinforced responding as exemplified by the pattern found near the end of the interval. Thus, behavior from clearly scalloped performance can be classified into three states: postreinforcement pause, interim behavior, and terminal behavior. 31 references, 11 figures, 4 tables.

  8. Advanced Interval Management: A Benefit Analysis

    NASA Technical Reports Server (NTRS)

    Timer, Sebastian; Peters, Mark

    2016-01-01

    This document is the final report for the NASA Langley Research Center (LaRC)- sponsored task order 'Possible Benefits for Advanced Interval Management Operations.' Under this research project, Architecture Technology Corporation performed an analysis to determine the maximum potential benefit to be gained if specific Advanced Interval Management (AIM) operations were implemented in the National Airspace System (NAS). The motivation for this research is to guide NASA decision-making on which Interval Management (IM) applications offer the most potential benefit and warrant further research.

  9. Importance of QT interval in clinical practice.

    PubMed

    Ambhore, Anand; Teo, Swee-Guan; Bin Omar, Abdul Razakjr; Poh, Kian-Keong

    2014-12-01

    Long QT interval is an important finding that is often missed by electrocardiogram interpreters. Long QT syndrome (inherited and acquired) is a potentially lethal cardiac channelopathy that is frequently mistaken for epilepsy. We present a case of long QT syndrome with multiple cardiac arrests presenting as syncope and seizures. The long QTc interval was aggravated by hypomagnesaemia and drugs, including clarithromycin and levofloxacin. Multiple drugs can cause prolongation of the QT interval, and all physicians should bear this in mind when prescribing these drugs.

  10. Globally convergent autocalibration using interval analysis.

    PubMed

    Fusiello, Andrea; Benedetti, Arrigo; Farenzena, Michela; Busti, Alessandro

    2004-12-01

    We address the problem of autocalibration of a moving camera with unknown constant intrinsic parameters. Existing autocalibration techniques use numerical optimization algorithms whose convergence to the correct result cannot be guaranteed, in general. To address this problem, we have developed a method where an interval branch-and-bound method is employed for numerical minimization. Thanks to the properties of Interval Analysis this method converges to the global solution with mathematical certainty and arbitrary accuracy and the only input information it requires from the user are a set of point correspondences and a search interval. The cost function is based on the Huang-Faugeras constraint of the essential matrix. A recently proposed interval extension based on Bernstein polynomial forms has been investigated to speed up the search for the solution. Finally, experimental results are presented. PMID:15573823

  11. Efficient Computation Of Confidence Intervals Of Parameters

    NASA Technical Reports Server (NTRS)

    Murphy, Patrick C.

    1992-01-01

    Study focuses on obtaining efficient algorithm for estimation of confidence intervals of ML estimates. Four algorithms selected to solve associated constrained optimization problem. Hybrid algorithms, following search and gradient approaches, prove best.

  12. Predictive intervals for age-specific fertility.

    PubMed

    Keilman, N; Pham, D Q

    2000-03-01

    A multivariate ARIMA model is combined with a Gamma curve to predict confidence intervals for age-specific birth rates by 1-year age groups. The method is applied to observed age-specific births in Norway between 1900 and 1995, and predictive intervals are computed for each year up to 2050. The predicted two-thirds confidence intervals for Total Fertility (TF) around 2010 agree well with TF errors in old population forecasts made by Statistics Norway. The method gives useful predictions for age-specific fertility up to the years 2020-30. For later years, the intervals become too wide. Methods that do not take into account estimation errors in the ARIMA model coefficients underestimate the uncertainty for future TF values. The findings suggest that the margin between high and low fertility variants in official population forecasts for many Western countries are too narrow. PMID:12158991

  13. Intact Interval Timing in Circadian CLOCK Mutants

    PubMed Central

    Cordes, Sara; Gallistel, C. R.

    2008-01-01

    While progress has been made in determining the molecular basis for the circadian clock, the mechanism by which mammalian brains time intervals measured in seconds to minutes remains a mystery. An obvious question is whether the interval timing mechanism shares molecular machinery with the circadian timing mechanism. In the current study, we trained circadian CLOCK +/− and −/− mutant male mice in a peak-interval procedure with 10 and 20-s criteria. The mutant mice were more active than their wild-type littermates, but there were no reliable deficits in the accuracy or precision of their timing as compared with wild-type littermates. This suggests that expression of the CLOCK protein is not necessary for normal interval timing. PMID:18602902

  14. Almost primes in almost all short intervals

    NASA Astrophysics Data System (ADS)

    TERÄVÄINEN, JONI

    2016-09-01

    Let $E_k$ be the set of positive integers having exactly $k$ prime factors. We show that almost all intervals $[x,x+\\log^{1+\\varepsilon} x]$ contain $E_3$ numbers, and almost all intervals $[x,x+\\log^{3.51} x]$ contain $E_2$ numbers. By this we mean that there are only $o(X)$ integers $1\\leq x\\leq X$ for which the mentioned intervals do not contain such numbers. The result for $E_3$ numbers is optimal up to the $\\varepsilon$ in the exponent. The theorem on $E_2$ numbers improves a result of Harman, which had the exponent $7+\\varepsilon$ in place of $3.51$. We will also consider general $E_k$ numbers, and find them on intervals whose lengths approach $\\log x$ as $k\\to \\infty$.

  15. Calibration intervals at Bendix Kansas City

    SciTech Connect

    James, R.T.

    1980-01-01

    The calibration interval evaluation methods and control in each calibrating department of the Bendix Corp., Kansas City Division is described, and a more detailed description of those employed in metrology is provided.

  16. SOPIE: Sequential Off-Pulse Interval Estimation

    NASA Astrophysics Data System (ADS)

    Schutte, Willem D.

    2016-07-01

    SOPIE (Sequential Off-Pulse Interval Estimation) provides functions to non-parametrically estimate the off-pulse interval of a source function originating from a pulsar. The technique is based on a sequential application of P-values obtained from goodness-of-fit tests for the uniform distribution, such as the Kolmogorov-Smirnov, Cramér-von Mises, Anderson-Darling and Rayleigh goodness-of-fit tests.

  17. Probability Distribution for Flowing Interval Spacing

    SciTech Connect

    S. Kuzio

    2004-09-22

    Fracture spacing is a key hydrologic parameter in analyses of matrix diffusion. Although the individual fractures that transmit flow in the saturated zone (SZ) cannot be identified directly, it is possible to determine the fractured zones that transmit flow from flow meter survey observations. The fractured zones that transmit flow as identified through borehole flow meter surveys have been defined in this report as flowing intervals. The flowing interval spacing is measured between the midpoints of each flowing interval. The determination of flowing interval spacing is important because the flowing interval spacing parameter is a key hydrologic parameter in SZ transport modeling, which impacts the extent of matrix diffusion in the SZ volcanic matrix. The output of this report is input to the ''Saturated Zone Flow and Transport Model Abstraction'' (BSC 2004 [DIRS 170042]). Specifically, the analysis of data and development of a data distribution reported herein is used to develop the uncertainty distribution for the flowing interval spacing parameter for the SZ transport abstraction model. Figure 1-1 shows the relationship of this report to other model reports that also pertain to flow and transport in the SZ. Figure 1-1 also shows the flow of key information among the SZ reports. It should be noted that Figure 1-1 does not contain a complete representation of the data and parameter inputs and outputs of all SZ reports, nor does it show inputs external to this suite of SZ reports. Use of the developed flowing interval spacing probability distribution is subject to the limitations of the assumptions discussed in Sections 5 and 6 of this analysis report. The number of fractures in a flowing interval is not known. Therefore, the flowing intervals are assumed to be composed of one flowing zone in the transport simulations. This analysis may overestimate the flowing interval spacing because the number of fractures that contribute to a flowing interval cannot be

  18. Musical intervals and relative pitch: Frequency resolution, not interval resolution, is special

    PubMed Central

    McDermott, Josh H.; Keebler, Michael V.; Micheyl, Christophe; Oxenham, Andrew J.

    2010-01-01

    Pitch intervals are central to most musical systems, which utilize pitch at the expense of other acoustic dimensions. It seemed plausible that pitch might uniquely permit precise perception of the interval separating two sounds, as this could help explain its importance in music. To explore this notion, a simple discrimination task was used to measure the precision of interval perception for the auditory dimensions of pitch, brightness, and loudness. Interval thresholds were then expressed in units of just-noticeable differences for each dimension, to enable comparison across dimensions. Contrary to expectation, when expressed in these common units, interval acuity was actually worse for pitch than for loudness or brightness. This likely indicates that the perceptual dimension of pitch is unusual not for interval perception per se, but rather for the basic frequency resolution it supports. The ubiquity of pitch in music may be due in part to this fine-grained basic resolution. PMID:20968366

  19. Sunspot Time Series: Passive and Active Intervals

    NASA Astrophysics Data System (ADS)

    Zięba, S.; Nieckarz, Z.

    2014-07-01

    Solar activity slowly and irregularly decreases from the first spotless day (FSD) in the declining phase of the old sunspot cycle and systematically, but also in an irregular way, increases to the new cycle maximum after the last spotless day (LSD). The time interval between the first and the last spotless day can be called the passive interval (PI), while the time interval from the last spotless day to the first one after the new cycle maximum is the related active interval (AI). Minima of solar cycles are inside PIs, while maxima are inside AIs. In this article, we study the properties of passive and active intervals to determine the relation between them. We have found that some properties of PIs, and related AIs, differ significantly between two group of solar cycles; this has allowed us to classify Cycles 8 - 15 as passive cycles, and Cycles 17 - 23 as active ones. We conclude that the solar activity in the PI declining phase (a descending phase of the previous cycle) determines the strength of the approaching maximum in the case of active cycles, while the activity of the PI rising phase (a phase of the ongoing cycle early growth) determines the strength of passive cycles. This can have implications for solar dynamo models. Our approach indicates the important role of solar activity during the declining and the rising phases of the solar-cycle minimum.

  20. Dietary reference intervals for vitamin D.

    PubMed

    Cashman, Kevin D

    2012-01-01

    Dietary reference intervals relate to the distribution of dietary requirement for a particular nutrient as defined by the distribution of physiological requirement for that nutrient. These have more commonly been called Dietary Reference Values (DRV) or Dietary Reference Intakes (DRI), amongst other names. The North American DRI for vitamin D are the most current dietary reference intervals and arguably arising from the most comprehensive evaluation and report on vitamin D nutrition to date. These are a family of nutrient reference values, including the Estimated Average Requirement (EAR), the Recommended Dietary Allowance (RDA), the Adequate Intake, and Tolerable Upper Intake Level. In particular, the EAR is used for planning and assessing diets of populations; it also serves as the basis for calculating the RDA, a value intended to meet the needs of nearly all people. The DRVs for vitamin D in the UK and the European Community have been in existence for almost two decades, and both are currently under review. The present paper briefly overviews these three sets of dietary reference intervals as case studies to highlight both the similarities as well as possible differences that may exist between reference intervals for vitamin D in different countries/regions. In addition, it highlights the scientific basis upon which these are based, which may explain some of the differences. Finally, it also overviews how the dietary reference intervals for vitamin D may be applied, and especially in terms of assessing the adequacy of vitamin D intake in populations. PMID:22536775

  1. Pigeons' choices between fixed-interval and random-interval schedules: utility of variability?

    PubMed

    Andrzejewski, Matthew E; Cardinal, Claudia D; Field, Douglas P; Flannery, Barbara A; Johnson, Michael; Bailey, Kathleen; Hineline, Philip N

    2005-03-01

    Pigeons' choosing between fixed-interval and random-interval schedules of reinforcement was investigated in three experiments using a discrete-trial procedure. In all three experiments, the random-interval schedule was generated by sampling a probability distribution at an interval (and in multiples of the interval) equal to that of the fixed-interval schedule. Thus the programmed delays to reinforcement on the random alternative were never shorter and were often longer than the fixed interval. Despite this feature, the fixed schedule was not strongly preferred. Increases in the probability used to generate the random interval resulted in decreased preferences for the fixed schedule. In addition, the number of consecutive choices on the preferred alternative varied directly with preference, whereas the consecutive number of choices on the nonpreferred alternative was fairly constant. The probability of choosing the random alternative was unaffected by the immediately prior interval encountered on that schedule, even when it was very long relative to the average value. The results loosely support conceptions of a "preference for variability" from foraging theory and the "utility of behavioral variability" from human decision-making literatures.

  2. Statistics of return intervals between long heartbeat intervals and their usability for online prediction of disorders

    NASA Astrophysics Data System (ADS)

    Bogachev, Mikhail I.; Kireenkov, Igor S.; Nifontov, Eugene M.; Bunde, Armin

    2009-06-01

    We study the statistics of return intervals between large heartbeat intervals (above a certain threshold Q) in 24 h records obtained from healthy subjects. We find that both the linear and the nonlinear long-term memory inherent in the heartbeat intervals lead to power-laws in the probability density function PQ(r) of the return intervals. As a consequence, the probability WQ(t; Δt) that at least one large heartbeat interval will occur within the next Δt heartbeat intervals, with an increasing elapsed number of intervals t after the last large heartbeat interval, follows a power-law. Based on these results, we suggest a method of obtaining a priori information about the occurrence of the next large heartbeat interval, and thus to predict it. We show explicitly that the proposed method, which exploits long-term memory, is superior to the conventional precursory pattern recognition technique, which focuses solely on short-term memory. We believe that our results can be straightforwardly extended to obtain more reliable predictions in other physiological signals like blood pressure, as well as in other complex records exhibiting multifractal behaviour, e.g. turbulent flow, precipitation, river flows and network traffic.

  3. Radial basis function networks with linear interval regression weights for symbolic interval data.

    PubMed

    Su, Shun-Feng; Chuang, Chen-Chia; Tao, C W; Jeng, Jin-Tsong; Hsiao, Chih-Ching

    2012-02-01

    This paper introduces a new structure of radial basis function networks (RBFNs) that can successfully model symbolic interval-valued data. In the proposed structure, to handle symbolic interval data, the Gaussian functions required in the RBFNs are modified to consider interval distance measure, and the synaptic weights of the RBFNs are replaced by linear interval regression weights. In the linear interval regression weights, the lower and upper bounds of the interval-valued data as well as the center and range of the interval-valued data are considered. In addition, in the proposed approach, two stages of learning mechanisms are proposed. In stage 1, an initial structure (i.e., the number of hidden nodes and the adjustable parameters of radial basis functions) of the proposed structure is obtained by the interval competitive agglomeration clustering algorithm. In stage 2, a gradient-descent kind of learning algorithm is applied to fine-tune the parameters of the radial basis function and the coefficients of the linear interval regression weights. Various experiments are conducted, and the average behavior of the root mean square error and the square of the correlation coefficient in the framework of a Monte Carlo experiment are considered as the performance index. The results clearly show the effectiveness of the proposed structure.

  4. Perceptual interference decays over short unfilled intervals.

    PubMed

    Schulkind, M D

    2000-09-01

    The perceptual interference effect refers to the fact that object identification is directly related to the amount of information available at initial exposure. The present article investigated whether perceptual interference would dissipate when a short, unfilled interval was introduced between exposures to a degraded object. Across three experiments using both musical and pictorial stimuli, identification performance increased directly with the length of the unfilled interval. Consequently, significant perceptual interference was obtained only when the interval between exposures was relatively short (< 500 msec for melodies; < 300 msec for pictures). These results are consistent with explanations that attribute perceptual interference to increased perceptual noise created by exposures to highly degraded objects. The data also suggest that perceptual interference is mediated by systems that are not consciously controlled by the subject and that perceptual interference in the visual domain decays more rapidly than perceptual interference in the auditory domain. PMID:11105520

  5. Atomic momentum patterns with narrower intervals

    NASA Astrophysics Data System (ADS)

    Yang, Baoguo; Jin, Shengjie; Dong, Xiangyu; Liu, Zhe; Yin, Lan; Zhou, Xiaoji

    2016-10-01

    We studied the atomic momentum distribution of a superposition of Bloch states in the lowest band of an optical lattice after the action of the standing-wave pulse. By designing the imposing pulse on this superposed state, an atomic momentum pattern appears with a narrow interval between the adjacent peaks that can be far less than double recoil momentum. The patterns with narrower interval come from the effect of the designed pulse on the superposition of many Bloch states with quasimomenta throughout the first Brillouin zone. Our experimental result of narrow interval peaks is consistent with the theoretical simulation. The patterns of multiple modes with different quasimomenta may be helpful for precise measurement and atomic manipulation.

  6. New delay-interval stability condition

    NASA Astrophysics Data System (ADS)

    Souza, Fernando O.; Palhares, Reinaldo M.

    2014-03-01

    The delay-dependent stability problem for systems with time-delay varying in an interval is addressed in this article. The new idea in this article is to connect two very efficient approaches: the discretised Lyapunov functional for systems with pointwise delay and the convex analysis for systems with time-varying delay. The proposed method is able to check the stability interval when the time-varying delay d(t) belongs to an interval [r, τ]. The case of unstable delayed systems for r = 0 is also treatable. The resulting criterion, expressed in terms of a convex optimisation problem, outperforms the existing ones in the literature, as illustrated by the numerical examples.

  7. Interval prediction in structural dynamic analysis

    NASA Technical Reports Server (NTRS)

    Hasselman, Timothy K.; Chrostowski, Jon D.; Ross, Timothy J.

    1992-01-01

    Methods for assessing the predictive accuracy of structural dynamic models are examined with attention given to the effects of modal mass, stiffness, and damping uncertainties. The methods are based on a nondeterministic analysis called 'interval prediction' in which interval variables are used to describe parameters and responses that are unknown. Statistical databases for generic modeling uncertainties are derived from experimental data and incorporated analytically to evaluate responses. Covariance matrices of modal mass, stiffness, and damping parameters are propagated numerically in models of large space structures by means of three methods. The test data tend to fall within the predicted intervals of uncertainty determined by the statistical databases. The present findings demonstrate the suitability of using data from previously analyzed and tested space structures for assessing the predictive accuracy of an analytical model.

  8. Intervality and coherence in complex networks.

    PubMed

    Domínguez-García, Virginia; Johnson, Samuel; Muñoz, Miguel A

    2016-06-01

    Food webs-networks of predators and prey-have long been known to exhibit "intervality": species can generally be ordered along a single axis in such a way that the prey of any given predator tend to lie on unbroken compact intervals. Although the meaning of this axis-usually identified with a "niche" dimension-has remained a mystery, it is assumed to lie at the basis of the highly non-trivial structure of food webs. With this in mind, most trophic network modelling has for decades been based on assigning species a niche value by hand. However, we argue here that intervality should not be considered the cause but rather a consequence of food-web structure. First, analysing a set of 46 empirical food webs, we find that they also exhibit predator intervality: the predators of any given species are as likely to be contiguous as the prey are, but in a different ordering. Furthermore, this property is not exclusive of trophic networks: several networks of genes, neurons, metabolites, cellular machines, airports, and words are found to be approximately as interval as food webs. We go on to show that a simple model of food-web assembly which does not make use of a niche axis can nevertheless generate significant intervality. Therefore, the niche dimension (in the sense used for food-web modelling) could in fact be the consequence of other, more fundamental structural traits. We conclude that a new approach to food-web modelling is required for a deeper understanding of ecosystem assembly, structure, and function, and propose that certain topological features thought to be specific of food webs are in fact common to many complex networks. PMID:27368797

  9. Intervality and coherence in complex networks

    NASA Astrophysics Data System (ADS)

    Domínguez-García, Virginia; Johnson, Samuel; Muñoz, Miguel A.

    2016-06-01

    Food webs—networks of predators and prey—have long been known to exhibit "intervality": species can generally be ordered along a single axis in such a way that the prey of any given predator tend to lie on unbroken compact intervals. Although the meaning of this axis—usually identified with a "niche" dimension—has remained a mystery, it is assumed to lie at the basis of the highly non-trivial structure of food webs. With this in mind, most trophic network modelling has for decades been based on assigning species a niche value by hand. However, we argue here that intervality should not be considered the cause but rather a consequence of food-web structure. First, analysing a set of 46 empirical food webs, we find that they also exhibit predator intervality: the predators of any given species are as likely to be contiguous as the prey are, but in a different ordering. Furthermore, this property is not exclusive of trophic networks: several networks of genes, neurons, metabolites, cellular machines, airports, and words are found to be approximately as interval as food webs. We go on to show that a simple model of food-web assembly which does not make use of a niche axis can nevertheless generate significant intervality. Therefore, the niche dimension (in the sense used for food-web modelling) could in fact be the consequence of other, more fundamental structural traits. We conclude that a new approach to food-web modelling is required for a deeper understanding of ecosystem assembly, structure, and function, and propose that certain topological features thought to be specific of food webs are in fact common to many complex networks.

  10. Intervality and coherence in complex networks.

    PubMed

    Domínguez-García, Virginia; Johnson, Samuel; Muñoz, Miguel A

    2016-06-01

    Food webs-networks of predators and prey-have long been known to exhibit "intervality": species can generally be ordered along a single axis in such a way that the prey of any given predator tend to lie on unbroken compact intervals. Although the meaning of this axis-usually identified with a "niche" dimension-has remained a mystery, it is assumed to lie at the basis of the highly non-trivial structure of food webs. With this in mind, most trophic network modelling has for decades been based on assigning species a niche value by hand. However, we argue here that intervality should not be considered the cause but rather a consequence of food-web structure. First, analysing a set of 46 empirical food webs, we find that they also exhibit predator intervality: the predators of any given species are as likely to be contiguous as the prey are, but in a different ordering. Furthermore, this property is not exclusive of trophic networks: several networks of genes, neurons, metabolites, cellular machines, airports, and words are found to be approximately as interval as food webs. We go on to show that a simple model of food-web assembly which does not make use of a niche axis can nevertheless generate significant intervality. Therefore, the niche dimension (in the sense used for food-web modelling) could in fact be the consequence of other, more fundamental structural traits. We conclude that a new approach to food-web modelling is required for a deeper understanding of ecosystem assembly, structure, and function, and propose that certain topological features thought to be specific of food webs are in fact common to many complex networks.

  11. Optimal Colonoscopy Surveillance Interval after Polypectomy

    PubMed Central

    Kim, Tae Oh

    2016-01-01

    The detection and removal of adenomatous polyps and postpolypectomy surveillance are considered important for the control of colorectal cancer (CRC). Surveillance using colonoscopy is an effective tool for preventing CRC after colorectal polypectomy, especially if compliance is good. In current practice, the intervals between colonoscopies after polypectomy are variable. Different recommendations for recognizing at risk groups and defining surveillance intervals after an initial finding of colorectal adenomas have been published. However, high-grade dysplasia and the number and size of adenomas are known major cancer predictors. Based on this, a subgroup of patients that may benefit from intensive surveillance colonoscopy can be identified. PMID:27484812

  12. Feedback precision and postfeedback interval duration

    NASA Technical Reports Server (NTRS)

    Rogers, C. A., Jr.

    1974-01-01

    Precision of feedback gain was manipulated in a simple positioning task. An optimum was found; an increase in precision past that optimum produced deleterious effects upon rate of acquisition. In a second study, increasing postfeedback interval removed that optimum. The feedback precision effects were then replicated in a timing task. The combined results of the 3 studies were interpreted as supportive of an information-processing approach to the study of postfeedback interval events for simple motor skills. The findings additionally supported specific predictions by Bilodeau and deductions from Adams' 1971 theory of motor learning.

  13. An Empirical Method for Establishing Positional Confidence Intervals Tailored for Composite Interval Mapping of QTL

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Improved genetic resolution and availability of sequenced genomes have made positional cloning of moderate-effect QTL (quantitative trait loci) realistic in several systems, emphasizing the need for precise and accurate derivation of positional confidence intervals (CIs). Support interval (SI) meth...

  14. Happiness Scale Interval Study. Methodological Considerations

    ERIC Educational Resources Information Center

    Kalmijn, W. M.; Arends, L. R.; Veenhoven, R.

    2011-01-01

    The Happiness Scale Interval Study deals with survey questions on happiness, using verbal response options, such as "very happy" and "pretty happy". The aim is to estimate what degrees of happiness are denoted by such terms in different questions and languages. These degrees are expressed in numerical values on a continuous [0,10] scale, which are…

  15. Duration perception in crossmodally-defined intervals.

    PubMed

    Mayer, Katja M; Di Luca, Massimiliano; Ernst, Marc O

    2014-03-01

    How humans perform duration judgments with multisensory stimuli is an ongoing debate. Here, we investigated how sub-second duration judgments are achieved by asking participants to compare the duration of a continuous sound to the duration of an empty interval in which onset and offset were marked by signals of different modalities using all combinations of visual, auditory and tactile stimuli. The pattern of perceived durations across five stimulus durations (ranging from 100 ms to 900 ms) follows the Vierordt Law. Furthermore, intervals with a sound as onset (audio-visual, audio-tactile) are perceived longer than intervals with a sound as offset. No modality ordering effect is found for visualtactile intervals. To infer whether a single modality-independent or multiple modality-dependent time-keeping mechanisms exist we tested whether perceived duration follows a summative or a multiplicative distortion pattern by fitting a model to all modality combinations and durations. The results confirm that perceived duration depends on sensory latency (summative distortion). Instead, we did not find evidence for multiplicative distortions. The results of the model and the behavioural data support the concept of a single time-keeping mechanism that allows for judgments of durations marked by multisensory stimuli. PMID:23953664

  16. Computation of confidence intervals for Poisson processes

    NASA Astrophysics Data System (ADS)

    Aguilar-Saavedra, J. A.

    2000-07-01

    We present an algorithm which allows a fast numerical computation of Feldman-Cousins confidence intervals for Poisson processes, even when the number of background events is relatively large. This algorithm incorporates an appropriate treatment of the singularities that arise as a consequence of the discreteness of the variable.

  17. Confidence Trick: The Interpretation of Confidence Intervals

    ERIC Educational Resources Information Center

    Foster, Colin

    2014-01-01

    The frequent misinterpretation of the nature of confidence intervals by students has been well documented. This article examines the problem as an aspect of the learning of mathematical definitions and considers the tension between parroting mathematically rigorous, but essentially uninternalized, statements on the one hand and expressing…

  18. Interval scanning photomicrography of microbial cell populations.

    NASA Technical Reports Server (NTRS)

    Casida, L. E., Jr.

    1972-01-01

    A single reproducible area of the preparation in a fixed focal plane is photographically scanned at intervals during incubation. The procedure can be used for evaluating the aerobic or anaerobic growth of many microbial cells simultaneously within a population. In addition, the microscope is not restricted to the viewing of any one microculture preparation, since the slide cultures are incubated separately from the microscope.

  19. Equidistant Intervals in Perspective Photographs and Paintings

    PubMed Central

    2016-01-01

    Human vision is extremely sensitive to equidistance of spatial intervals in the frontal plane. Thresholds for spatial equidistance have been extensively measured in bisecting tasks. Despite the vast number of studies, the informational basis for equidistance perception is unknown. There are three possible sources of information for spatial equidistance in pictures, namely, distances in the picture plane, in physical space, and visual space. For each source, equidistant intervals were computed for perspective photographs of walls and canals. Intervals appear equidistant if equidistance is defined in visual space. Equidistance was further investigated in paintings of perspective scenes. In appraisals of the perspective skill of painters, emphasis has been on accurate use of vanishing points. The current study investigated the skill of painters to depict equidistant intervals. Depicted rows of equidistant columns, tiles, tapestries, or trees were analyzed in 30 paintings and engravings. Computational analysis shows that from the middle ages until now, artists either represented equidistance in physical space or in a visual space of very limited depth. Among the painters and engravers who depict equidistance in a highly nonveridical visual space are renowned experts of linear perspective.

  20. Equidistant Intervals in Perspective Photographs and Paintings

    PubMed Central

    2016-01-01

    Human vision is extremely sensitive to equidistance of spatial intervals in the frontal plane. Thresholds for spatial equidistance have been extensively measured in bisecting tasks. Despite the vast number of studies, the informational basis for equidistance perception is unknown. There are three possible sources of information for spatial equidistance in pictures, namely, distances in the picture plane, in physical space, and visual space. For each source, equidistant intervals were computed for perspective photographs of walls and canals. Intervals appear equidistant if equidistance is defined in visual space. Equidistance was further investigated in paintings of perspective scenes. In appraisals of the perspective skill of painters, emphasis has been on accurate use of vanishing points. The current study investigated the skill of painters to depict equidistant intervals. Depicted rows of equidistant columns, tiles, tapestries, or trees were analyzed in 30 paintings and engravings. Computational analysis shows that from the middle ages until now, artists either represented equidistance in physical space or in a visual space of very limited depth. Among the painters and engravers who depict equidistance in a highly nonveridical visual space are renowned experts of linear perspective. PMID:27698983

  1. Precise Interval Timer for Software Defined Radio

    NASA Technical Reports Server (NTRS)

    Pozhidaev, Aleksey (Inventor)

    2014-01-01

    A precise digital fractional interval timer for software defined radios which vary their waveform on a packet-by-packet basis. The timer allows for variable length in the preamble of the RF packet and allows to adjust boundaries of the TDMA (Time Division Multiple Access) Slots of the receiver of an SDR based on the reception of the RF packet of interest.

  2. Coefficient Alpha Bootstrap Confidence Interval under Nonnormality

    ERIC Educational Resources Information Center

    Padilla, Miguel A.; Divers, Jasmin; Newton, Matthew

    2012-01-01

    Three different bootstrap methods for estimating confidence intervals (CIs) for coefficient alpha were investigated. In addition, the bootstrap methods were compared with the most promising coefficient alpha CI estimation methods reported in the literature. The CI methods were assessed through a Monte Carlo simulation utilizing conditions…

  3. Coefficient Omega Bootstrap Confidence Intervals: Nonnormal Distributions

    ERIC Educational Resources Information Center

    Padilla, Miguel A.; Divers, Jasmin

    2013-01-01

    The performance of the normal theory bootstrap (NTB), the percentile bootstrap (PB), and the bias-corrected and accelerated (BCa) bootstrap confidence intervals (CIs) for coefficient omega was assessed through a Monte Carlo simulation under conditions not previously investigated. Of particular interests were nonnormal Likert-type and binary items.…

  4. Toward Using Confidence Intervals to Compare Correlations

    ERIC Educational Resources Information Center

    Zou, Guang Yong

    2007-01-01

    Confidence intervals are widely accepted as a preferred way to present study results. They encompass significance tests and provide an estimate of the magnitude of the effect. However, comparisons of correlations still rely heavily on significance testing. The persistence of this practice is caused primarily by the lack of simple yet accurate…

  5. MEETING DATA QUALITY OBJECTIVES WITH INTERVAL INFORMATION

    EPA Science Inventory

    Immunoassay test kits are promising technologies for measuring analytes under field conditions. Frequently, these field-test kits report the analyte concentrations as falling in an interval between minimum and maximum values. Many project managers use field-test kits only for scr...

  6. A prospective evaluation of non-interval- and interval-based exercise training progressions in rodents.

    PubMed

    Jendzjowsky, Nicholas G; DeLorey, Darren S

    2011-10-01

    Non-interval and interval training progressions were used to determine (i) the mean rate at which treadmill speed could be incremented daily using a non-interval training progression to train rats to run continuously at different intensities and (ii) the number of training days required for rats to run continuously at different exercise intensities with non-interval- and interval-based training progressions to establish methods of progressive overload for rodent exercise training studies. Rats were randomly assigned to mild-intensity (n = 5, 20 m·min(-1), 5% grade), moderate-intensity (n = 5, 30 m·min(-1), 5% grade), and heavy-intensity non-interval groups (n = 5, 40 m·min(-1), 5% grade) or a heavy-intensity interval (n = 5, 40 m·min(-1), 5% grade) group and ran 5 days·week(-1) for 6 weeks. Non-interval training involved a daily increase of treadmill speed, whereas interval training involved a daily increase of interval time, until the animal could run continuously at a prescribed intensity. In mild-, moderate-, and heavy-intensity non-interval-trained rats, treadmill speed was increased by 0.6 ± 0.7 m·min(-1)·day(-1), 0.6 ± 0.2 m·min(-1)·day(-1), and 0.8 ± 0.1 m·min(-1)·day(-1), respectively. Target training intensity and duration were obtained following 0.4 ± 0.5 days, 17 ± 3 days, and 23 ± 3 training days (p < 0.05) in mild-, moderate-, and heavy-intensity groups, respectively. In contrast, interval-trained rodents required 11 ± 1 training days. These data demonstrate that rodents will tolerate an increase in treadmill speed of ∼0.7 ± 0.1 m·min(-1)·day(-1) and that this progression enables rats to run continuously at moderate and heavy intensities with 3-4 weeks of progressive overload. Interval training significantly reduces the number of training days required to attain a target intensity.

  7. Constraint-based Attribute and Interval Planning

    NASA Technical Reports Server (NTRS)

    Jonsson, Ari; Frank, Jeremy

    2013-01-01

    In this paper we describe Constraint-based Attribute and Interval Planning (CAIP), a paradigm for representing and reasoning about plans. The paradigm enables the description of planning domains with time, resources, concurrent activities, mutual exclusions among sets of activities, disjunctive preconditions and conditional effects. We provide a theoretical foundation for the paradigm, based on temporal intervals and attributes. We then show how the plans are naturally expressed by networks of constraints, and show that the process of planning maps directly to dynamic constraint reasoning. In addition, we de ne compatibilities, a compact mechanism for describing planning domains. We describe how this framework can incorporate the use of constraint reasoning technology to improve planning. Finally, we describe EUROPA, an implementation of the CAIP framework.

  8. Efficient computation of parameter confidence intervals

    NASA Technical Reports Server (NTRS)

    Murphy, Patrick C.

    1987-01-01

    An important step in system identification of aircraft is the estimation of stability and control derivatives from flight data along with an assessment of parameter accuracy. When the maximum likelihood estimation technique is used, parameter accuracy is commonly assessed by the Cramer-Rao lower bound. It is known, however, that in some cases the lower bound can be substantially different from the parameter variance. Under these circumstances the Cramer-Rao bounds may be misleading as an accuracy measure. This paper discusses the confidence interval estimation problem based on likelihood ratios, which offers a more general estimate of the error bounds. Four approaches are considered for computing confidence intervals of maximum likelihood parameter estimates. Each approach is applied to real flight data and compared.

  9. Temporal control in fixed-interval schedules.

    PubMed

    Zeiler, M D; Powell, D G

    1994-01-01

    The peak procedure was used to study temporal control in pigeons exposed to seven fixed-interval schedules ranging from 7.5 to 480 s. The focus was on behavior in individual intervals. Quantitative properties of temporal control depended on whether the aspect of behavior considered was initial pause duration, the point of maximum acceleration in responding, the point of maximum deceleration, the point at which responding stopped, or several different statistical derivations of a point of maximum responding. Each aspect produced different conclusions about the nature of temporal control, and none conformed to what was known previously about the way ongoing responding was controlled by time under conditions of differential reinforcement. Existing theory does not explain why Weber's law so rarely fit the results or why each type of behavior seemed unique. These data fit with others suggesting that principles of temporal control may depend on the role played by the particular aspect of behavior in particular situations.

  10. The Rotator Interval of the Shoulder

    PubMed Central

    Frank, Rachel M.; Taylor, Dean; Verma, Nikhil N.; Romeo, Anthony A.; Mologne, Timothy S.; Provencher, Matthew T.

    2015-01-01

    Biomechanical studies have shown that repair or plication of rotator interval (RI) ligamentous and capsular structures decreases glenohumeral joint laxity in various directions. Clinical outcomes studies have reported successful outcomes after repair or plication of these structures in patients undergoing shoulder stabilization procedures. Recent studies describing arthroscopic techniques to address these structures have intensified the debate over the potential benefit of these procedures as well as highlighted the differences between open and arthroscopic RI procedures. The purposes of this study were to review the structures of the RI and their contribution to shoulder instability, to discuss the biomechanical and clinical effects of repair or plication of rotator interval structures, and to describe the various surgical techniques used for these procedures and outcomes. PMID:26779554

  11. Partitioned-Interval Quantum Optical Communications Receiver

    NASA Technical Reports Server (NTRS)

    Vilnrotter, Victor A.

    2013-01-01

    The proposed quantum receiver in this innovation partitions each binary signal interval into two unequal segments: a short "pre-measurement" segment in the beginning of the symbol interval used to make an initial guess with better probability than 50/50 guessing, and a much longer segment used to make the high-sensitivity signal detection via field-cancellation and photon-counting detection. It was found that by assigning as little as 10% of the total signal energy to the pre-measurement segment, the initial 50/50 guess can be improved to about 70/30, using the best available measurements such as classical coherent or "optimized Kennedy" detection.

  12. One-way ANOVA based on interval information

    NASA Astrophysics Data System (ADS)

    Hesamian, Gholamreza

    2016-08-01

    This paper deals with extending the one-way analysis of variance (ANOVA) to the case where the observed data are represented by closed intervals rather than real numbers. In this approach, first a notion of interval random variable is introduced. Especially, a normal distribution with interval parameters is introduced to investigate hypotheses about the equality of interval means or test the homogeneity of interval variances assumption. Moreover, the least significant difference (LSD method) for investigating multiple comparison of interval means is developed when the null hypothesis about the equality of means is rejected. Then, at a given interval significance level, an index is applied to compare the interval test statistic and the related interval critical value as a criterion to accept or reject the null interval hypothesis of interest. Finally, the method of decision-making leads to some degrees to accept or reject the interval hypotheses. An applied example will be used to show the performance of this method.

  13. Systolic Time Intervals and New Measurement Methods.

    PubMed

    Tavakolian, Kouhyar

    2016-06-01

    Systolic time intervals have been used to detect and quantify the directional changes of left ventricular function. New methods of recording these cardiac timings, which are less cumbersome, have been recently developed and this has created a renewed interest and novel applications for these cardiac timings. This manuscript reviews these new methods and addresses the potential for the application of these cardiac timings for the diagnosis and prognosis of different cardiac diseases.

  14. Psychophysical basis for consonant musical intervals

    NASA Astrophysics Data System (ADS)

    Resnick, L.

    1981-06-01

    A suggestion is made to explain the acceptance of certain musical intervals as consonant and others as dissonant. The proposed explanation involves the relation between the time required to perceive a definite pitch and the period of a complex tone. If the former time is greater than the latter, the tone is consonant; otherwise it is dissonant. A quantitative examination leads to agreement with empirical data.

  15. Quantifying chaotic dynamics from interspike intervals

    NASA Astrophysics Data System (ADS)

    Pavlov, A. N.; Pavlova, O. N.; Mohammad, Y. K.; Shihalov, G. M.

    2015-03-01

    We address the problem of characterization of chaotic dynamics at the input of a threshold device described by an integrate-and-fire (IF) or a threshold crossing (TC) model from the output sequences of interspike intervals (ISIs). We consider the conditions under which quite short sequences of spiking events provide correct identification of the dynamical regime characterized by the single positive Lyapunov exponent (LE). We discuss features of detecting the second LE for both types of the considered models of events generation.

  16. Fluctuations of healthy and unhealthy heartbeat intervals

    NASA Astrophysics Data System (ADS)

    Lan, Boon Leong; Toda, Mikito

    2013-04-01

    We show that the RR-interval fluctuations, defined as the difference between successive natural-logarithm of the RR interval, for healthy, congestive-heart-failure (CHF) and atrial-fibrillation (AF) subjects are well modeled by non-Gaussian stable distributions. Our results suggest that healthy or unhealthy RR-interval fluctuation can generally be modeled as a sum of a large number of independent physiological effects which are identically distributed with infinite variance. Furthermore, we show for the first time that one indicator —the scale parameter of the stable distribution— is sufficient to robustly distinguish the three groups of subjects. The scale parameters for healthy subjects are smaller than those for AF subjects but larger than those for CHF subjects —this ordering suggests that the scale parameter could be used to objectively quantify the severity of CHF and AF over time and also serve as an early warning signal for a healthy person when it approaches either boundary of the healthy range.

  17. Hyperplane arrangements, interval orders, and trees.

    PubMed Central

    Stanley, R P

    1996-01-01

    A hyperplane arrangement is a finite set of hyperplanes in a real affine space. An especially important arrangement is the braid arrangement, which is the set of all hyperplanes xi - xj = 1, 1 interval orders and with the enumeration of trees. For instance, the number of labeled interval orders that can be obtained from n intervals I1,..., In of generic lengths is counted. There is also discussed an arrangement due to N. Linial whose number of regions is the number of alternating (or intransitive) trees, as defined by Gelfand, Graev, and Postnikov [Gelfand, I. M., Graev, M. I., and Postnikov, A. (1995), preprint]. Finally, a refinement is given, related to counting labeled trees by number of inversions, of a result of Shi [Shi, J.-Y. (1986), Lecture Notes in Mathematics, no. 1179, Springer-Verlag] that a certain deformation of the braid arrangement has (n + 1)n-1 regions. PMID:11607643

  18. Easy identification of generalized common and conserved nested intervals.

    PubMed

    de Montgolfier, Fabien; Raffinot, Mathieu; Rusu, Irena

    2014-07-01

    In this article we explain how to easily compute gene clusters, formalized by classical or generalized nested common or conserved intervals, between a set of K genomes represented as K permutations. A b-nested common (resp. conserved) interval I of size |I| is either an interval of size 1 or a common (resp. conserved) interval that contains another b-nested common (resp. conserved) interval of size at least |I|-b. When b=1, this corresponds to the classical notion of nested interval. We exhibit two simple algorithms to output all b-nested common or conserved intervals between K permutations in O(Kn+nocc) time, where nocc is the total number of such intervals. We also explain how to count all b-nested intervals in O(Kn) time. New properties of the family of conserved intervals are proposed to do so.

  19. Easy identification of generalized common and conserved nested intervals.

    PubMed

    de Montgolfier, Fabien; Raffinot, Mathieu; Rusu, Irena

    2014-07-01

    In this article we explain how to easily compute gene clusters, formalized by classical or generalized nested common or conserved intervals, between a set of K genomes represented as K permutations. A b-nested common (resp. conserved) interval I of size |I| is either an interval of size 1 or a common (resp. conserved) interval that contains another b-nested common (resp. conserved) interval of size at least |I|-b. When b=1, this corresponds to the classical notion of nested interval. We exhibit two simple algorithms to output all b-nested common or conserved intervals between K permutations in O(Kn+nocc) time, where nocc is the total number of such intervals. We also explain how to count all b-nested intervals in O(Kn) time. New properties of the family of conserved intervals are proposed to do so. PMID:24650221

  20. Multiple interval mapping for quantitative trait loci.

    PubMed Central

    Kao, C H; Zeng, Z B; Teasdale, R D

    1999-01-01

    A new statistical method for mapping quantitative trait loci (QTL), called multiple interval mapping (MIM), is presented. It uses multiple marker intervals simultaneously to fit multiple putative QTL directly in the model for mapping QTL. The MIM model is based on Cockerham's model for interpreting genetic parameters and the method of maximum likelihood for estimating genetic parameters. With the MIM approach, the precision and power of QTL mapping could be improved. Also, epistasis between QTL, genotypic values of individuals, and heritabilities of quantitative traits can be readily estimated and analyzed. Using the MIM model, a stepwise selection procedure with likelihood ratio test statistic as a criterion is proposed to identify QTL. This MIM method was applied to a mapping data set of radiata pine on three traits: brown cone number, tree diameter, and branch quality scores. Based on the MIM result, seven, six, and five QTL were detected for the three traits, respectively. The detected QTL individually contributed from approximately 1 to 27% of the total genetic variation. Significant epistasis between four pairs of QTL in two traits was detected, and the four pairs of QTL contributed approximately 10.38 and 14.14% of the total genetic variation. The asymptotic variances of QTL positions and effects were also provided to construct the confidence intervals. The estimated heritabilities were 0.5606, 0.5226, and 0. 3630 for the three traits, respectively. With the estimated QTL effects and positions, the best strategy of marker-assisted selection for trait improvement for a specific purpose and requirement can be explored. The MIM FORTRAN program is available on the worldwide web (http://www.stat.sinica.edu.tw/chkao/). PMID:10388834

  1. Computing confidence intervals for standardized regression coefficients.

    PubMed

    Jones, Jeff A; Waller, Niels G

    2013-12-01

    With fixed predictors, the standard method (Cohen, Cohen, West, & Aiken, 2003, p. 86; Harris, 2001, p. 80; Hays, 1994, p. 709) for computing confidence intervals (CIs) for standardized regression coefficients fails to account for the sampling variability of the criterion standard deviation. With random predictors, this method also fails to account for the sampling variability of the predictor standard deviations. Nevertheless, under some conditions the standard method will produce CIs with accurate coverage rates. To delineate these conditions, we used a Monte Carlo simulation to compute empirical CI coverage rates in samples drawn from 36 populations with a wide range of data characteristics. We also computed the empirical CI coverage rates for 4 alternative methods that have been discussed in the literature: noncentrality interval estimation, the delta method, the percentile bootstrap, and the bias-corrected and accelerated bootstrap. Our results showed that for many data-parameter configurations--for example, sample size, predictor correlations, coefficient of determination (R²), orientation of β with respect to the eigenvectors of the predictor correlation matrix, RX--the standard method produced coverage rates that were close to their expected values. However, when population R² was large and when β approached the last eigenvector of RX, then the standard method coverage rates were frequently below the nominal rate (sometimes by a considerable amount). In these conditions, the delta method and the 2 bootstrap procedures were consistently accurate. Results using noncentrality interval estimation were inconsistent. In light of these findings, we recommend that researchers use the delta method to evaluate the sampling variability of standardized regression coefficients.

  2. Feedback functions for variable-interval reinforcement

    PubMed Central

    Nevin, John A.; Baum, William M.

    1980-01-01

    On a given variable-interval schedule, the average obtained rate of reinforcement depends on the average rate of responding. An expression for this feedback effect is derived from the assumptions that free-operant responding occurs in bursts with a constant tempo, alternating with periods of engagement in other activities; that the durations of bursts and other activities are exponentially distributed; and that the rates of initiating and terminating bursts are inversely related. The expression provides a satisfactory account of the data of three experiments. PMID:16812187

  3. Optimal ABC inventory classification using interval programming

    NASA Astrophysics Data System (ADS)

    Rezaei, Jafar; Salimi, Negin

    2015-08-01

    Inventory classification is one of the most important activities in inventory management, whereby inventories are classified into three or more classes. Several inventory classifications have been proposed in the literature, almost all of which have two main shortcomings in common. That is, the previous methods mainly rely on an expert opinion to derive the importance of the classification criteria which results in subjective classification, and they need precise item parameters before implementing the classification. While the problem has been predominantly considered as a multi-criteria, we examine the problem from a different perspective, proposing a novel optimisation model for ABC inventory classification in the form of an interval programming problem. The proposed interval programming model has two important features compared to the existing methods: it provides optimal results instead of an expert-based classification and it does not require precise values of item parameters, which are not almost always available before classification. Finally, by illustrating the proposed classification model in the form of numerical example, conclusion and suggestions for future works are presented.

  4. Multiple-interval timing in rats: Performance on two-valued mixed fixed-interval schedules.

    PubMed

    Whitaker, S; Lowe, C F; Wearden, J H

    2003-10-01

    Three experiments studied timing in rats on 2-valued mixed-fixed-interval schedules, with equally probable components, Fixed-Interval S and Fixed-Interval L (FI S and FI L, respectively). When the L:S ratio was greater than 4, 2 distinct response peaks appeared close to FI S and FI L, and data could be well fitted by the sum of 2 Gaussian curves. When the L:S ratio was less than 4, only 1 response peak was usually visible, but nonlinear regression often identified separate sources of behavioral control, by FI S and FI L, although control by FI L dominated. Data were used to test ideas derived from scalar expectancy theory, the behavioral theory of timing, and learning to time.

  5. Physiological Responses to High-Intensity Interval Exercise Differing in Interval Duration.

    PubMed

    Tucker, Wesley J; Sawyer, Brandon J; Jarrett, Catherine L; Bhammar, Dharini M; Gaesser, Glenn A

    2015-12-01

    We determined the oxygen uptake (V[Combining Dot Above]O2), heart rate (HR), and blood lactate responses to 2 high-intensity interval exercise protocols differing in interval length. On separate days, 14 recreationally active males performed a 4 × 4 (four 4-minute intervals at 90-95% HRpeak, separated by 3-minute recovery at 50 W) and 16 × 1 (sixteen 1-minute intervals at 90-95% HRpeak, separated by 1-minute recovery at 50 W) protocol on a cycle ergometer. The 4 × 4 elicited a higher mean V[Combining Dot Above]O2 (2.44 ± 0.4 vs. 2.36 ± 0.4 L·min) and "peak" V[Combining Dot Above]O2 (90-99% vs. 76-85% V[Combining Dot Above]O2peak) and HR (95-98% HRpeak vs. 81-95% HRpeak) during the high-intensity intervals. Average power maintained was higher for the 16 × 1 (241 ± 45 vs. 204 ± 37 W), and recovery interval V[Combining Dot Above]O2 and HR were higher during the 16 × 1. No differences were observed for blood lactate concentrations at the midpoint (12.1 ± 2.2 vs. 10.8 ± 3.1 mmol·L) and end (10.6 ± 1.5 vs. 10.6 ± 2.4 mmol·L) of the protocols or ratings of perceived exertion (7.0 ± 1.6 vs. 7.0 ± 1.4) and Physical Activity Enjoyment Scale scores (91 ± 15 vs. 93 ± 12). Despite a 4-fold difference in interval duration that produced greater between-interval transitions in V[Combining Dot Above]O2 and HR and slightly higher mean V[Combining Dot Above]O2 during the 4 × 4, mean HR during each protocol was the same, and both protocols were rated similarly for perceived exertion and enjoyment. The major difference was that power output had to be reduced during the 4 × 4 protocol to maintain the desired HR.

  6. A primer on confidence intervals in psychopharmacology.

    PubMed

    Andrade, Chittaranjan

    2015-02-01

    Research papers and research summaries frequently present results in the form of data accompanied by 95% confidence intervals (CIs). Not all students and clinicians know how to interpret CIs. This article provides a nontechnical, nonmathematical discussion on how to understand and glean information from CIs; all explanations are accompanied by simple examples. A statistically accurate explanation about CIs is also provided. CIs are differentiated from standard deviations, standard errors, and confidence levels. The interpretation of narrow and wide CIs is discussed. Factors that influence the width of a CI are listed. Explanations are provided for how CIs can be used to assess statistical significance. The significance of overlapping and nonoverlapping CIs is considered. It is concluded that CIs are far more informative than, say, mere P values when drawing conclusions about a result.

  7. The effect of instrumental timbre on interval discrimination.

    PubMed

    Zarate, Jean Mary; Ritson, Caroline R; Poeppel, David

    2013-01-01

    We tested non-musicians and musicians in an auditory psychophysical experiment to assess the effects of timbre manipulation on pitch-interval discrimination. Both groups were asked to indicate the larger of two presented intervals, comprised of four sequentially presented pitches; the second or fourth stimulus within a trial was either a sinusoidal (or "pure"), flute, piano, or synthetic voice tone, while the remaining three stimuli were all pure tones. The interval-discrimination tasks were administered parametrically to assess performance across varying pitch distances between intervals ("interval-differences"). Irrespective of timbre, musicians displayed a steady improvement across interval-differences, while non-musicians only demonstrated enhanced interval discrimination at an interval-difference of 100 cents (one semitone in Western music). Surprisingly, the best discrimination performance across both groups was observed with pure-tone intervals, followed by intervals containing a piano tone. More specifically, we observed that: 1) timbre changes within a trial affect interval discrimination; and 2) the broad spectral characteristics of an instrumental timbre may influence perceived pitch or interval magnitude and make interval discrimination more difficult. PMID:24066179

  8. The Effect of Instrumental Timbre on Interval Discrimination

    PubMed Central

    Zarate, Jean Mary; Ritson, Caroline R.; Poeppel, David

    2013-01-01

    We tested non-musicians and musicians in an auditory psychophysical experiment to assess the effects of timbre manipulation on pitch-interval discrimination. Both groups were asked to indicate the larger of two presented intervals, comprised of four sequentially presented pitches; the second or fourth stimulus within a trial was either a sinusoidal (or “pure”), flute, piano, or synthetic voice tone, while the remaining three stimuli were all pure tones. The interval-discrimination tasks were administered parametrically to assess performance across varying pitch distances between intervals (“interval-differences”). Irrespective of timbre, musicians displayed a steady improvement across interval-differences, while non-musicians only demonstrated enhanced interval discrimination at an interval-difference of 100 cents (one semitone in Western music). Surprisingly, the best discrimination performance across both groups was observed with pure-tone intervals, followed by intervals containing a piano tone. More specifically, we observed that: 1) timbre changes within a trial affect interval discrimination; and 2) the broad spectral characteristics of an instrumental timbre may influence perceived pitch or interval magnitude and make interval discrimination more difficult. PMID:24066179

  9. Pigeons' Memory for Number of Events: Effects of Intertrial Interval and Delay Interval Illumination

    ERIC Educational Resources Information Center

    Hope, Chris; Santi, Angelo

    2004-01-01

    In Experiment 1, pigeons were trained at a 0-s baseline delay to discriminate sequences of light flashes (illumination of the feeder) that varied in number but not time (2f/4s and 8f/4s). During training, the intertrial interval was illuminated by the houselight for Group Light, but it was dark for Group Dark. Testing conducted with dark delay…

  10. Confidence Intervals Make a Difference: Effects of Showing Confidence Intervals on Inferential Reasoning

    ERIC Educational Resources Information Center

    Hoekstra, Rink; Johnson, Addie; Kiers, Henk A. L.

    2012-01-01

    The use of confidence intervals (CIs) as an addition or as an alternative to null hypothesis significance testing (NHST) has been promoted as a means to make researchers more aware of the uncertainty that is inherent in statistical inference. Little is known, however, about whether presenting results via CIs affects how readers judge the…

  11. Application of Sequential Interval Estimation to Adaptive Mastery Testing

    ERIC Educational Resources Information Center

    Chang, Yuan-chin Ivan

    2005-01-01

    In this paper, we apply sequential one-sided confidence interval estimation procedures with beta-protection to adaptive mastery testing. The procedures of fixed-width and fixed proportional accuracy confidence interval estimation can be viewed as extensions of one-sided confidence interval procedures. It can be shown that the adaptive mastery…

  12. Exact Confidence Intervals in the Presence of Interference

    PubMed Central

    Rigdon, Joseph; Hudgens, Michael G.

    2015-01-01

    For two-stage randomized experiments assuming partial interference, exact confidence intervals are proposed for treatment effects on a binary outcome. Empirical studies demonstrate the new intervals have narrower width than previously proposed exact intervals based on the Hoeffding inequality. PMID:26190877

  13. Calculating Confidence Intervals for Effect Sizes Using Noncentral Distributions.

    ERIC Educational Resources Information Center

    Norris, Deborah

    This paper provides a brief review of the concepts of confidence intervals, effect sizes, and central and noncentral distributions. The use of confidence intervals around effect sizes is discussed. A demonstration of the Exploratory Software for Confidence Intervals (G. Cuming and S. Finch, 2001; ESCI) is given to illustrate effect size confidence…

  14. About Hemispheric Differences in the Processing of Temporal Intervals

    ERIC Educational Resources Information Center

    Grondin, S.; Girard, C.

    2005-01-01

    The purpose of the present study was to identify differences between cerebral hemispheres for processing temporal intervals ranging from .9 to 1.4s. The intervals to be judged were marked by series of brief visual signals located in the left or the right visual field. Series of three (two standards and one comparison) or five intervals (four…

  15. 30 CFR 75.360 - Preshift examination at fixed intervals.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Preshift examination at fixed intervals. 75.360... examination at fixed intervals. (a)(1) Except as provided in paragraph (a)(2) of this section, a certified... added and revised text is set forth as follows: § 75.360 Preshift examination at fixed intervals....

  16. High-intensity interval training: Modulating interval duration in overweight/obese men

    PubMed Central

    Smith-Ryan, Abbie E.; Melvin, Malia N.; Wingfield, Hailee L.

    2015-01-01

    Introduction High-intensity interval training (HIIT) is a time-efficient strategy shown to induce various cardiovascular and metabolic adaptations. Little is known about the optimal tolerable combination of intensity and volume necessary for adaptations, especially in clinical populations. Objectives In a randomized controlled pilot design, we evaluated the effects of two types of interval training protocols, varying in intensity and interval duration, on clinical outcomes in overweight/obese men. Methods Twenty-five men [body mass index (BMI) > 25 kg·m2] completed baseline body composition measures: fat mass (FM), lean mass (LM) and percent body fat (%BF) and fasting blood glucose, lipids and insulin (IN). A graded exercise cycling test was completed for peak oxygen consumption (VO2peak) and power output (PO). Participants were randomly assigned to high-intensity short interval (1MIN-HIIT), high-intensity interval (2MIN-HIIT) or control groups. 1MIN-HIIT and 2MIN-HIIT completed 3 weeks of cycling interval training, 3 days/week, consisting of either 10 × 1 min bouts at 90% PO with 1 min rests (1MIN-HIIT) or 5 × 2 min bouts with 1 min rests at undulating intensities (80%–100%) (2MIN-HIIT). Results There were no significant training effects on FM (Δ1.06 ± 1.25 kg) or %BF (Δ1.13% ± 1.88%), compared to CON. Increases in LM were not significant but increased by 1.7 kg and 2.1 kg for 1MIN and 2MIN-HIIT groups, respectively. Increases in VO2peak were also not significant for 1MIN (3.4 ml·kg−1·min−1) or 2MIN groups (2.7 ml·kg−1·min−1). IN sensitivity (HOMA-IR) improved for both training groups (Δ −2.78 ± 3.48 units; p < 0.05) compared to CON. Conclusion HIIT may be an effective short-term strategy to improve cardiorespiratory fitness and IN sensitivity in overweight males. PMID:25913937

  17. Restricted Interval Guelph permeameter: Theory andapplication

    SciTech Connect

    Freifeld, Barry M.; Oldenburg, Curtis M.

    2003-06-19

    A constant head permeameter system has been developed for use in small diameter boreholes with any orientation. It is based upon the original Guelph permeameter concept of using a Mariotte siphon reservoir to control the applied head. The new tool, called a Restricted Interval Guelph (RIG) permeameter uses either a single pneumatic packer or straddle packer to restrict the area through which water is allowed to flow so that the borehole wetted area is independent of the applied head. The RIG permeameter has been used at Yucca Mountain, Nevada, in the nonwelded rhyolitic Paintbrush Tuff. Analysis of the acquired data is based upon saturated-unsaturated flow theory that relies upon the quasi-linear approximation to estimate field-saturated hydraulic conductivity (Kfs) and the a parameter (sorptive number) of the exponential relative hydraulic conductivity pressure head relationship. These results are compared with a numerical model based upon the solution of the Richards equation using a van Genuchten capillary pressure-saturation formulation. The numerical model incorporates laboratory capillary pressure versus saturation functions measured from cores taken from nearby boreholes. Comparison between the analytical and numerical approaches shows that the simple analytic model is valid for analyzing the data collected. Sensitivity analysis performed with the numerical model shows that the RIG permeameter is an effective tool for estimating permeability and sorptive number for the nonwelded Paintbrush Tuff.

  18. An Investigation of Interval Management Displays

    NASA Technical Reports Server (NTRS)

    Swieringa, Kurt A.; Wilson, Sara R.; Shay, Rick

    2015-01-01

    NASA's first Air Traffic Management (ATM) Technology Demonstration (ATD-1) was created to transition the most mature ATM technologies from the laboratory to the National Airspace System. One selected technology is Interval Management (IM), which uses onboard aircraft automation to compute speeds that help the flight crew achieve and maintain precise spacing behind a preceding aircraft. Since ATD-1 focuses on a near-term environment, the ATD-1 flight demonstration prototype requires radio voice communication to issue an IM clearance. Retrofit IM displays will enable pilots to both enter information into the IM avionics and monitor IM operation. These displays could consist of an interface to enter data from an IM clearance and also an auxiliary display that presents critical information in the primary field-of-view. A human-in-the-loop experiment was conducted to examine usability and acceptability of retrofit IM displays, which flight crews found acceptable. Results also indicate the need for salient alerting when new speeds are generated and the desire to have a primary field of view display available that can display text and graphic trend indicators.

  19. Confidence intervals for ATR performance metrics

    NASA Astrophysics Data System (ADS)

    Ross, Timothy D.

    2001-08-01

    This paper describes confidence interval (CI) estimators (CIEs) for the metrics used to assess sensor exploitation algorithm (or ATR) performance. For the discrete distributions, small sample sizes and extreme outcomes encountered within ATR testing, the commonly used CIEs have limited accuracy. This paper makes available CIEs that are accurate over all conditions of interest to the ATR community. The approach is to search for CIs using an integration of the Bayesian posterior (IBP) to measure alpha (chance of the CI not containing the true value). The CIEs provided include proportion estimates based on Binomial distributions and rate estimates based on Poisson distributions. One or two-sided CIs may be selected. For two-sided CIEs, either minimal length, balanced tail probabilities, or balanced width may be selected. The CIEs' accuracies are reported based on a Monte Carlo validated integration of the posterior probability distribution and compared to the Normal approximation and `exact' (Clopper- Pearson) methods. While the IBP methods are accurate throughout, the conventional methods may realize alphas with substantial error (up to 50%). This translates to 10 to 15% error in the CI widths or to requiring 10 to 15% more samples for a given confidence level.

  20. Statistical Properties of Extreme Solar Activity Intervals

    NASA Astrophysics Data System (ADS)

    Lioznova, A. V.; Blinov, A. V.

    2014-01-01

    A study of long-term solar variability reflected in indirect indices of past solar activity leads to stimulating results. We compare the statistics of intervals of very low and very high solar activity derived from two cosmogenic radionuclide records and look for consistency in their timing and physical interpretation. According to the applied criteria, the numbers of minima and of maxima are 61 and 68, respectively, from the 10Be record, and 42 and 46 from the 14C record. The difference between the enhanced and depressed states of solar activity becomes apparent in the difference in their statistical distributions. We find no correlation between the level or type (minimum or maximum) of an extremum and the level or type of the predecessor. The hypothesis of solar activity as a periodic process on the millennial time scale is not supported by the existing proxies. A new homogeneous series of 10Be measurements in polar ice covering the Holocene would be of great value for eliminating the existing discrepancy in the available solar activity reconstructions.

  1. Controlling human fixed-interval performance.

    PubMed

    Weiner, H

    1969-05-01

    Both high and relatively constant rates of responding without post-reinforcement pauses and lower rates with pauses after reinforcement are produced by human subjects under fixed-interval (FI) schedules. Such FI rates and patterns may be controlled when subjects are provided with different histories of conditioning and different conditions of response cost (reinforcement penalties per response). Subjects with a conditioning history under ratio schedules typically produce high and relatively constant rates of responding under FI schedules; this responding does not change systematically with changes in FI value. In contrast, subjects with a history under schedules which produce little or no responding between reforcements [such as differential-reinforcement-of-low-rate (DRL) schedules] tend to pause after reinforcement and respond at low rates under FI schedules, whether or not they also have ratio conditioning histories; cost increases the likelihood of this type of performance. For DRL-history subjects, post-reinforcement pauses increase and response rates decrease as FI values increase.

  2. Function approximation using adaptive and overlapping intervals

    SciTech Connect

    Patil, R.B.

    1995-05-01

    A problem common to many disciplines is to approximate a function given only the values of the function at various points in input variable space. A method is proposed for approximating a function of several to one variable. The model takes the form of weighted averaging of overlapping basis functions defined over intervals. The number of such basis functions and their parameters (widths and centers) are automatically determined using given training data and a learning algorithm. The proposed algorithm can be seen as placing a nonuniform multidimensional grid in the input domain with overlapping cells. The non-uniformity and overlap of the cells is achieved by a learning algorithm to optimize a given objective function. This approach is motivated by the fuzzy modeling approach and a learning algorithms used for clustering and classification in pattern recognition. The basics of why and how the approach works are given. Few examples of nonlinear regression and classification are modeled. The relationship between the proposed technique, radial basis neural networks, kernel regression, probabilistic neural networks, and fuzzy modeling is explained. Finally advantages and disadvantages are discussed.

  3. Dissimilar Physiological and Perceptual Responses Between Sprint Interval Training and High-Intensity Interval Training.

    PubMed

    Wood, Kimberly M; Olive, Brittany; LaValle, Kaylyn; Thompson, Heather; Greer, Kevin; Astorino, Todd A

    2016-01-01

    High-intensity interval training (HIIT) and sprint interval training (SIT) elicit similar cardiovascular and metabolic adaptations vs. endurance training. No study, however, has investigated acute physiological changes during HIIT vs. SIT. This study compared acute changes in heart rate (HR), blood lactate concentration (BLa), oxygen uptake (VO2), affect, and rating of perceived exertion (RPE) during HIIT and SIT. Active adults (4 women and 8 men, age = 24.2 ± 6.2 years) initially performed a VO2max test to determine workload for both sessions on the cycle ergometer, whose order was randomized. Sprint interval training consisted of 8 bouts of 30 seconds of all-out cycling at 130% of maximum Watts (Wmax). High-intensity interval training consisted of eight 60-second bouts at 85% Wmax. Heart rate, VO2, BLa, affect, and RPE were continuously assessed throughout exercise. Repeated-measures analysis of variance revealed a significant difference between HIIT and SIT for VO2 (p < 0.001), HR (p < 0.001), RPE (p = 0.03), and BLa (p = 0.049). Conversely, there was no significant difference between regimens for affect (p = 0.12). Energy expenditure was significantly higher (p = 0.02) in HIIT (209.3 ± 40.3 kcal) vs. SIT (193.5 ± 39.6 kcal). During HIIT, subjects burned significantly more calories and reported lower perceived exertion than SIT. The higher VO2 and lower BLa in HIIT vs. SIT reflected dissimilar metabolic perturbation between regimens, which may elicit unique long-term adaptations. If an individual is seeking to burn slightly more calories, maintain a higher oxygen uptake, and perceive less exertion during exercise, HIIT is the recommended routine.

  4. Dissimilar Physiological and Perceptual Responses Between Sprint Interval Training and High-Intensity Interval Training.

    PubMed

    Wood, Kimberly M; Olive, Brittany; LaValle, Kaylyn; Thompson, Heather; Greer, Kevin; Astorino, Todd A

    2016-01-01

    High-intensity interval training (HIIT) and sprint interval training (SIT) elicit similar cardiovascular and metabolic adaptations vs. endurance training. No study, however, has investigated acute physiological changes during HIIT vs. SIT. This study compared acute changes in heart rate (HR), blood lactate concentration (BLa), oxygen uptake (VO2), affect, and rating of perceived exertion (RPE) during HIIT and SIT. Active adults (4 women and 8 men, age = 24.2 ± 6.2 years) initially performed a VO2max test to determine workload for both sessions on the cycle ergometer, whose order was randomized. Sprint interval training consisted of 8 bouts of 30 seconds of all-out cycling at 130% of maximum Watts (Wmax). High-intensity interval training consisted of eight 60-second bouts at 85% Wmax. Heart rate, VO2, BLa, affect, and RPE were continuously assessed throughout exercise. Repeated-measures analysis of variance revealed a significant difference between HIIT and SIT for VO2 (p < 0.001), HR (p < 0.001), RPE (p = 0.03), and BLa (p = 0.049). Conversely, there was no significant difference between regimens for affect (p = 0.12). Energy expenditure was significantly higher (p = 0.02) in HIIT (209.3 ± 40.3 kcal) vs. SIT (193.5 ± 39.6 kcal). During HIIT, subjects burned significantly more calories and reported lower perceived exertion than SIT. The higher VO2 and lower BLa in HIIT vs. SIT reflected dissimilar metabolic perturbation between regimens, which may elicit unique long-term adaptations. If an individual is seeking to burn slightly more calories, maintain a higher oxygen uptake, and perceive less exertion during exercise, HIIT is the recommended routine. PMID:26691413

  5. Volatility return intervals analysis of the Japanese market

    NASA Astrophysics Data System (ADS)

    Jung, W.-S.; Wang, F. Z.; Havlin, S.; Kaizoji, T.; Moon, H.-T.; Stanley, H. E.

    2008-03-01

    We investigate scaling and memory effects in return intervals between price volatilities above a certain threshold q for the Japanese stock market using daily and intraday data sets. We find that the distribution of return intervals can be approximated by a scaling function that depends only on the ratio between the return interval τ and its mean <τ>. We also find memory effects such that a large (or small) return interval follows a large (or small) interval by investigating the conditional distribution and mean return interval. The results are similar to previous studies of other markets and indicate that similar statistical features appear in different financial markets. We also compare our results between the period before and after the big crash at the end of 1989. We find that scaling and memory effects of the return intervals show similar features although the statistical properties of the returns are different.

  6. Using Confidence Intervals and Recurrence Intervals to Determine Precipitation Delivery Mechanisms Responsible for Mass Wasting Events.

    NASA Astrophysics Data System (ADS)

    Ulizio, T. P.; Bilbrey, C.; Stoyanoff, N.; Dixon, J. L.

    2015-12-01

    Mass wasting events are geologic hazards that impact human life and property across a variety of landscapes. These movements can be triggered by tectonic activity, anomalous precipitation events, or both; acting to decrease the factor of safety ratio on a hillslope to the point of failure. There exists an active hazard landscape in the West Boulder River drainage of Park Co., MT in which the mechanisms of slope failure are unknown. It is known that region has not seen significant tectonic activity within the last decade, leaving anomalous precipitation events as the likely trigger for slope failures in the landscape. Precipitation can be delivered to a landscape via rainfall or snow; it was the aim of this study to determine the precipitation delivery mechanism most likely responsible for movements in the West Boulder drainage following the Jungle Wildfire of 2006. Data was compiled from four SNOTEL sites in the surrounding area, spanning 33 years, focusing on, but not limited to; maximum snow water equivalent (SWE) values in a water year, median SWE values on the date which maximum SWE was recorded in a water year, the total precipitation accumulated in a water year, etc. Means were computed and 99% confidence intervals were constructed around these means. Recurrence intervals and exceedance probabilities were computed for maximum SWE values and total precipitation accumulated in a water year to determine water years with anomalous precipitation. It was determined that the water year 2010-2011 received an anomalously high amount of SWE, and snow melt in the spring of this water year likely triggered recent mass waste movements. This data is further supported by Google Earth imagery, showing movements between 2009 and 2011. Return intervals for the maximum SWE value in 2010-11 for the Placer Basin SNOTEL site was 34 years, while return intervals for the Box Canyon and Monument Peak SNOTEL sites were 17.5 and 17 years respectively. Max SWE values lie outside the

  7. IBM system/360 assembly language interval arithmetic software

    NASA Technical Reports Server (NTRS)

    Phillips, E. J.

    1972-01-01

    Computer software designed to perform interval arithmetic is described. An interval is defined as the set of all real numbers between two given numbers including or excluding one or both endpoints. Interval arithmetic consists of the various elementary arithmetic operations defined on the set of all intervals, such as interval addition, subtraction, union, etc. One of the main applications of interval arithmetic is in the area of error analysis of computer calculations. For example, it has been used sucessfully to compute bounds on sounding errors in the solution of linear algebraic systems, error bounds in numerical solutions of ordinary differential equations, as well as integral equations and boundary value problems. The described software enables users to implement algorithms of the type described in references efficiently on the IBM 360 system.

  8. Contrasting diversity values: statistical inferences based on overlapping confidence intervals.

    PubMed

    MacGregor-Fors, Ian; Payton, Mark E

    2013-01-01

    Ecologists often contrast diversity (species richness and abundances) using tests for comparing means or indices. However, many popular software applications do not support performing standard inferential statistics for estimates of species richness and/or density. In this study we simulated the behavior of asymmetric log-normal confidence intervals and determined an interval level that mimics statistical tests with P(α) = 0.05 when confidence intervals from two distributions do not overlap. Our results show that 84% confidence intervals robustly mimic 0.05 statistical tests for asymmetric confidence intervals, as has been demonstrated for symmetric ones in the past. Finally, we provide detailed user-guides for calculating 84% confidence intervals in two of the most robust and highly-used freeware related to diversity measurements for wildlife (i.e., EstimateS, Distance).

  9. Contrasting Diversity Values: Statistical Inferences Based on Overlapping Confidence Intervals

    PubMed Central

    MacGregor-Fors, Ian; Payton, Mark E.

    2013-01-01

    Ecologists often contrast diversity (species richness and abundances) using tests for comparing means or indices. However, many popular software applications do not support performing standard inferential statistics for estimates of species richness and/or density. In this study we simulated the behavior of asymmetric log-normal confidence intervals and determined an interval level that mimics statistical tests with P(α) = 0.05 when confidence intervals from two distributions do not overlap. Our results show that 84% confidence intervals robustly mimic 0.05 statistical tests for asymmetric confidence intervals, as has been demonstrated for symmetric ones in the past. Finally, we provide detailed user-guides for calculating 84% confidence intervals in two of the most robust and highly-used freeware related to diversity measurements for wildlife (i.e., EstimateS, Distance). PMID:23437239

  10. Interval timing in Siamese fighting fish (Betta splendens).

    PubMed

    Higa, J J; Simm, L A

    2004-11-30

    The present study evaluated the temporal performance of Siamese fighting fish (Betta splendens) given short-term exposure to four fixed interval (FI) schedules of reinforcement, FI 30, 60, 120, and 240 s, during which a reinforcer (mirror image) was given for the first response (swimming through a hoop) after the interval requirement had elapsed. Response levels were generally low early in an interval and increased as the interval elapsed; wait times and break points in an interval increased with increases in the FI requirement. The results were similar to that obtained with other species and different types of responses and reinforcers, and demonstrate that the procedure is a feasible method for studying interval timing in fish.

  11. Interval timing in Siamese fighting fish (Betta splendens).

    PubMed

    Higa, J J; Simm, L A

    2004-11-30

    The present study evaluated the temporal performance of Siamese fighting fish (Betta splendens) given short-term exposure to four fixed interval (FI) schedules of reinforcement, FI 30, 60, 120, and 240 s, during which a reinforcer (mirror image) was given for the first response (swimming through a hoop) after the interval requirement had elapsed. Response levels were generally low early in an interval and increased as the interval elapsed; wait times and break points in an interval increased with increases in the FI requirement. The results were similar to that obtained with other species and different types of responses and reinforcers, and demonstrate that the procedure is a feasible method for studying interval timing in fish. PMID:15518999

  12. Hydrologic studies in wells open through large intervals

    SciTech Connect

    Not Available

    1992-01-01

    This report describes and summarizes activities, data, and preliminary data interpretation from the INEL Oversight Program R D-1 project titled Hydrologic Studies In Wells Open Through Large Intervals.'' The project is designed to use a straddle-packer system to isolate, hydraulically test, and sample specific intervals of monitoring wells that are open (uncased, unscreened) over large intervals of the Snake River Plain aquifer. The objectives of the project are to determine and compare vertical variations in water quality and aquifer properties that have previously only been determined in an integrated fashion over the entire thickness of the open interval of the observation wells.

  13. Interval-valued fuzzy hypergraph and fuzzy partition.

    PubMed

    Chen, S M

    1997-01-01

    This paper extends the work of H. Lee-Kwang and L.M. Lee (1995) to present the concept of the interval-valued fuzzy hypergraph. In the interval-valued fuzzy hypergraph, the concepts of the dual interval-valued fuzzy hypergraph, the crisp-valued alpha-cut hypergraph, and the interval-valued [alpha(1),alpha(2 )]-cut at beta level hypergraph are developed, where alphain [0, 1], 0

  14. Relationship between inter-stimulus-intervals and intervals of autonomous activities in a neuronal network.

    PubMed

    Ito, Hidekatsu; Minoshima, Wataru; Kudoh, Suguru N

    2015-08-01

    To investigate relationships between neuronal network activity and electrical stimulus, we analyzed autonomous activity before and after electrical stimulus. Recordings of autonomous activity were performed using dissociated culture of rat hippocampal neurons on a multi-electrodes array (MEA) dish. Single stimulus and pared stimuli were applied to a cultured neuronal network. Single stimulus was applied every 1 min, and paired stimuli was performed by two sequential stimuli every 1 min. As a result, the patterns of synchronized activities of a neuronal network were changed after stimulus. Especially, long range synchronous activities were induced by paired stimuli. When 1 s inter-stimulus-intervals (ISI) and 1.5 s ISI paired stimuli are applied to a neuronal network, relatively long range synchronous activities expressed in case of 1.5 s ISI. Temporal synchronous activity of neuronal network is changed according to inter-stimulus-intervals (ISI) of electrical stimulus. In other words, dissociated neuronal network can maintain given information in temporal pattern and a certain type of an information maintenance mechanism was considered to be implemented in a semi-artificial dissociated neuronal network. The result is useful toward manipulation technology of neuronal activity in a brain system.

  15. The different effects of high intensity interval training and moderate intensity interval training for weightlessness countermeasures

    NASA Astrophysics Data System (ADS)

    Wang, Lin-Jie; Cheng, Tan; Zhi-Li, Li; Hui-juan, Wang; Wen-juan, Chen; Jianfeng, Zhang; Desheng, Wang; Dongbin, Niu; Qi, Zhao; Chengjia, Yang; Yanqing, Wang

    High intensity interval training (HIIT) has been demonstrated to improve performance in a relatively short training period. But the difference between high intensity interval training and moderate intensity interval training (MIIT) in simulated weightlessness still has not been well studied. This study sought to characterize the difference between 6 weeks high intensity interval training and moderate intensity interval training under reduced weight (RW) gait training device and zero-gravity locomotion system (ZLS). Twenty-three subjects (14M/4F, 32.5±4.5 years) volunteered to participate. They were divided into three groups, that were MITT (alternating 2 min at 40% VO _{2} peak and 2 min at 60% VO _{2} peak for 30min, five days per week) RW group (n=8), HITT (alternating 2 min at 40% VO _{2} peak and 2 min at 90% VO _{2} peak for 30min, three days per week) RW group (n=8) and HITT ZLS group (n=7). The Z-axis load used in RW group was 80% body weight (BW) and in ZLS was 100% BW. Cardiopulmonary function was measured before, after 4-week training and after 6-week training. Isokinetic knee extension-flexion test at 60(°) deg/s and 180(°) deg/s were performed before and after the 6-week training, and isometric knee extension-flexion test at 180(°) deg/s was also examined at the same time. It was found that the VO _{2} peaks, metabolic equivalent (MET), Speedmax and respiratory exchange ratio (RER) were significantly increased after 4 and 6-week training in all three groups and no significant group difference were detected. The peak torque at 60(°) deg/s for right knee flexion were significantly increased after 6 week-training in all three groups, and only in HITT RW group the total power at 60(°) deg/s for right knee flexion enhanced. The total power and average power at 60(°) deg/s for right knee extension decreased significantly after 6-week training in all three groups. The peak torque at 60(°) deg/s for right knee extension in MIIT RW group was

  16. Comparing interval estimates for small sample ordinal CFA models.

    PubMed

    Natesan, Prathiba

    2015-01-01

    Robust maximum likelihood (RML) and asymptotically generalized least squares (AGLS) methods have been recommended for fitting ordinal structural equation models. Studies show that some of these methods underestimate standard errors. However, these studies have not investigated the coverage and bias of interval estimates. An estimate with a reasonable standard error could still be severely biased. This can only be known by systematically investigating the interval estimates. The present study compares Bayesian, RML, and AGLS interval estimates of factor correlations in ordinal confirmatory factor analysis models (CFA) for small sample data. Six sample sizes, 3 factor correlations, and 2 factor score distributions (multivariate normal and multivariate mildly skewed) were studied. Two Bayesian prior specifications, informative and relatively less informative were studied. Undercoverage of confidence intervals and underestimation of standard errors was common in non-Bayesian methods. Underestimated standard errors may lead to inflated Type-I error rates. Non-Bayesian intervals were more positive biased than negatively biased, that is, most intervals that did not contain the true value were greater than the true value. Some non-Bayesian methods had non-converging and inadmissible solutions for small samples and non-normal data. Bayesian empirical standard error estimates for informative and relatively less informative priors were closer to the average standard errors of the estimates. The coverage of Bayesian credibility intervals was closer to what was expected with overcoverage in a few cases. Although some Bayesian credibility intervals were wider, they reflected the nature of statistical uncertainty that comes with the data (e.g., small sample). Bayesian point estimates were also more accurate than non-Bayesian estimates. The results illustrate the importance of analyzing coverage and bias of interval estimates, and how ignoring interval estimates can be misleading

  17. Interval Estimation of Gamma for an "RxS" Table

    ERIC Educational Resources Information Center

    Lui, Kung-Jong; Cumberland, William G.

    2004-01-01

    When the underlying responses are on an ordinal scale, gamma is one of the most frequently used indices to measure the strength of association between two ordered variables. However, except for a brief mention on the use of the traditional interval estimator based on Wald's statistic, discussion of interval estimation of the gamma is limited.…

  18. Reporting Confidence Intervals and Effect Sizes: Collecting the Evidence

    ERIC Educational Resources Information Center

    Zientek, Linda Reichwein; Ozel, Z. Ebrar Yetkiner; Ozel, Serkan; Allen, Jeff

    2012-01-01

    Confidence intervals (CIs) and effect sizes are essential to encourage meta-analytic thinking and to accumulate research findings. CIs provide a range of plausible values for population parameters with a degree of confidence that the parameter is in that particular interval. CIs also give information about how precise the estimates are. Comparison…

  19. A comparison of approximate interval estimators for the Bernoulli parameter

    NASA Technical Reports Server (NTRS)

    Leemis, Lawrence; Trivedi, Kishor S.

    1993-01-01

    The goal of this paper is to compare the accuracy of two approximate confidence interval estimators for the Bernoulli parameter p. The approximate confidence intervals are based on the normal and Poisson approximations to the binomial distribution. Charts are given to indicate which approximation is appropriate for certain sample sizes and point estimators.

  20. A Note on Confidence Interval Estimation and Margin of Error

    ERIC Educational Resources Information Center

    Gilliland, Dennis; Melfi, Vince

    2010-01-01

    Confidence interval estimation is a fundamental technique in statistical inference. Margin of error is used to delimit the error in estimation. Dispelling misinterpretations that teachers and students give to these terms is important. In this note, we give examples of the confusion that can arise in regard to confidence interval estimation and…

  1. Improved central confidence intervals for the ratio of Poisson means

    NASA Astrophysics Data System (ADS)

    Cousins, R. D.

    The problem of confidence intervals for the ratio of two unknown Poisson means was "solved" decades ago, but a closer examination reveals that the standard solution is far from optimal from the frequentist point of view. We construct a more powerful set of central confidence intervals, each of which is a (typically proper) subinterval of the corresponding standard interval. They also provide upper and lower confidence limits which are more restrictive than the standard limits. The construction follows Neyman's original prescription, though discreteness of the Poisson distribution and the presence of a nuisance parameter (one of the unknown means) lead to slightly conservative intervals. Philosophically, the issue of the appropriateness of the construction method is similar to the issue of conditioning on the margins in 2×2 contingency tables. From a frequentist point of view, the new set maintains (over) coverage of the unknown true value of the ratio of means at each stated confidence level, even though the new intervals are shorter than the old intervals by any measure (except for two cases where they are identical). As an example, when the number 2 is drawn from each Poisson population, the 90% CL central confidence interval on the ratio of means is (0.169, 5.196), rather than (0.108, 9.245). In the cited literature, such confidence intervals have applications in numerous branches of pure and applied science, including agriculture, wildlife studies, manufacturing, medicine, reliability theory, and elementary particle physics.

  2. Confidence Intervals for Effect Sizes: Applying Bootstrap Resampling

    ERIC Educational Resources Information Center

    Banjanovic, Erin S.; Osborne, Jason W.

    2016-01-01

    Confidence intervals for effect sizes (CIES) provide readers with an estimate of the strength of a reported statistic as well as the relative precision of the point estimate. These statistics offer more information and context than null hypothesis statistic testing. Although confidence intervals have been recommended by scholars for many years,…

  3. Sample Size for the "Z" Test and Its Confidence Interval

    ERIC Educational Resources Information Center

    Liu, Xiaofeng Steven

    2012-01-01

    The statistical power of a significance test is closely related to the length of the confidence interval (i.e. estimate precision). In the case of a "Z" test, the length of the confidence interval can be expressed as a function of the statistical power. (Contains 1 figure and 1 table.)

  4. [Experimental visual evoked potentials. Interstimuli interval and cortical excitability].

    PubMed

    Díaz Calavia, E; Fernández del Moral, R; Dawid-Milner, S; Jiménez Vargas, J

    1989-01-01

    The excitability of the visual system was studied in ten adult chronic cats. Visual evoked potentials were recorded, using decreasing interstimulus intervals. A decrease of the excitability of the visual system is observed when interstimulus intervals are less than 800 milliseconds. Clinical applications with regard to visual evoked potential recording on comatose patients are suggested.

  5. Computer Experience and Interval-Based Hypermedia Navigation.

    ERIC Educational Resources Information Center

    Reed, W. Michael; Oughton, John M.

    1997-01-01

    Describes a study of graduate students that focused on determining the relationship among student characteristics, including gender, learning style, and prior computer experiences, and non-linear interval-based navigation of a hypermedia program. Highlights include a literature review, interval frequencies, and suggestions for future research.…

  6. Overconfidence in Interval Estimates: What Does Expertise Buy You?

    ERIC Educational Resources Information Center

    McKenzie, Craig R. M.; Liersch, Michael J.; Yaniv, Ilan

    2008-01-01

    People's 90% subjective confidence intervals typically contain the true value about 50% of the time, indicating extreme overconfidence. Previous results have been mixed regarding whether experts are as overconfident as novices. Experiment 1 examined interval estimates from information technology (IT) professionals and UC San Diego (UCSD) students…

  7. A Model for Residence Time in Concurrent Variable Interval Performance

    ERIC Educational Resources Information Center

    Navakatikyan, Michael A.

    2007-01-01

    A component-functions model of choice behavior is proposed for performance on interdependent concurrent variable-interval (VI) variable-interval schedules based on the product of two component functions, one that enhances behavior and one that reduces behavior. The model is the solution to the symmetrical pair of differential equations describing…

  8. Why Aren't They Called Probability Intervals?

    ERIC Educational Resources Information Center

    Devlin, Thomas F.

    2008-01-01

    This article offers suggestions for teaching confidence intervals, a fundamental statistical tool often misinterpreted by beginning students. A historical perspective presenting the interpretation given by their inventor is supported with examples and the use of technology. A method for determining confidence intervals for the seldom-discussed…

  9. Min and Max Exponential Extreme Interval Values and Statistics

    ERIC Educational Resources Information Center

    Jance, Marsha; Thomopoulos, Nick

    2009-01-01

    The extreme interval values and statistics (expected value, median, mode, standard deviation, and coefficient of variation) for the smallest (min) and largest (max) values of exponentially distributed variables with parameter ? = 1 are examined for different observation (sample) sizes. An extreme interval value g[subscript a] is defined as a…

  10. Magnitude Estimation Reveals Temporal Binding at Super-Second Intervals

    ERIC Educational Resources Information Center

    Humphreys, Gruffydd R.; Buehner, Marc J.

    2009-01-01

    Several recent studies (e.g., Haggard, Aschersleben, Gehrke, & Prinz, 2002; Haggard & Clark, 2003; Haggard, Clark, & Kalogeras, 2002) have demonstrated a "Temporal Binding" effect in which the interval between an intentional action and its consequent outcome is subjectively shorter compared to equivalent intervals that do not involve intentional…

  11. Habituation in goldfish (Carassius auratus) is impaired by increased interstimulus interval, interval variability, and telencephalic ablation.

    PubMed

    Laming, P R; McKinney, S J

    1990-12-01

    Goldfish (Carassius auratus) were fitted with electrodes and buccal catheters for monitoring electrocardiograms and ventilations, respectively. A 2-s "light-on" stimulus was repeatedly presented to groups of fish at fixed interstimulus intervals (ISIs) of 1 or 2 min or at variable ISIs with a mean duration of 1 or 2 min. Normal fish, fish with telencephalic ablation, and fish with sham operations were compared for responsiveness and habituation to repeatedly presented stimuli. The longer the ISI, the greater the number of stimuli that were required for habituation. Increased ISI variability also decreased the rate of habituation. Furthermore, fish with telencephalic ablation had significantly slower habituation rates with both fixed and variable ISI schedules.

  12. Interval sampling methods and measurement error: a computer simulation.

    PubMed

    Wirth, Oliver; Slaven, James; Taylor, Matthew A

    2014-01-01

    A simulation study was conducted to provide a more thorough account of measurement error associated with interval sampling methods. A computer program simulated the application of momentary time sampling, partial-interval recording, and whole-interval recording methods on target events randomly distributed across an observation period. The simulation yielded measures of error for multiple combinations of observation period, interval duration, event duration, and cumulative event duration. The simulations were conducted up to 100 times to yield measures of error variability. Although the present simulation confirmed some previously reported characteristics of interval sampling methods, it also revealed many new findings that pertain to each method's inherent strengths and weaknesses. The analysis and resulting error tables can help guide the selection of the most appropriate sampling method for observation-based behavioral assessments.

  13. Order and chaos in fixed-interval schedules of reinforcement

    PubMed Central

    Hoyert, Mark S.

    1992-01-01

    Fixed-interval schedule performance is characterized by high levels of variability. Responding is absent at the onset of the interval and gradually increases in frequency until reinforcer delivery. Measures of behavior also vary drastically and unpredictably between successive intervals. Recent advances in the study of nonlinear dynamics have allowed researchers to study irregular and unpredictable behavior in a number of fields. This paper reviews several concepts and techniques from nonlinear dynamics and examines their utility in predicting the behavior of pigeons responding to a fixed-interval schedule of reinforcement. The analysis provided fairly accurate a priori accounts of response rates, accounting for 92.8% of the variance when predicting response rate 1 second in the future and 64% of the variance when predicting response rates for each second over the entire next interreinforcer interval. The nonlinear dynamics account suggests that even the “noisiest” behavior might be the product of purely deterministic mechanisms. PMID:16812657

  14. Plea for routinely presenting prediction intervals in meta-analysis

    PubMed Central

    IntHout, Joanna; Ioannidis, John P A; Rovers, Maroeska M; Goeman, Jelle J

    2016-01-01

    Objectives Evaluating the variation in the strength of the effect across studies is a key feature of meta-analyses. This variability is reflected by measures like τ2 or I2, but their clinical interpretation is not straightforward. A prediction interval is less complicated: it presents the expected range of true effects in similar studies. We aimed to show the advantages of having the prediction interval routinely reported in meta-analyses. Design We show how the prediction interval can help understand the uncertainty about whether an intervention works or not. To evaluate the implications of using this interval to interpret the results, we selected the first meta-analysis per intervention review of the Cochrane Database of Systematic Reviews Issues 2009–2013 with a dichotomous (n=2009) or continuous (n=1254) outcome, and generated 95% prediction intervals for them. Results In 72.4% of 479 statistically significant (random-effects p<0.05) meta-analyses in the Cochrane Database 2009–2013 with heterogeneity (I2>0), the 95% prediction interval suggested that the intervention effect could be null or even be in the opposite direction. In 20.3% of those 479 meta-analyses, the prediction interval showed that the effect could be completely opposite to the point estimate of the meta-analysis. We demonstrate also how the prediction interval can be used to calculate the probability that a new trial will show a negative effect and to improve the calculations of the power of a new trial. Conclusions The prediction interval reflects the variation in treatment effects over different settings, including what effect is to be expected in future patients, such as the patients that a clinician is interested to treat. Prediction intervals should be routinely reported to allow more informative inferences in meta-analyses. PMID:27406637

  15. Changes in QT interval before and after hemodialysis

    PubMed Central

    Khosoosi Niaki, Mohammad Reza; Saravi, Mehrdad; Oliaee, Farshid; Akbari, Roghayeh; Noorkhomami, Sepideh; Bozorgi Rad, Seyed Hassan; Fallahpoor, Kobra; Ramezani, Mir Saeed

    2013-01-01

    Background: Cardiovascular mortality and morbidity are high in chronic renal failure (CRF) patients. Increased dispersion of QT intervals is known to predispose to ventricular arrhythmias and sudden cardiac death. This study was conducted to assess the effect of hemodialysis (HD) on corrected QT (QTc) intervals and their dispersions (QTd) in chronic hemodialyzed patients. Methods: Fifty-eight patients ( mean age 54.2±15.8 years) with chronic renal disease on chronic hemodialysis (HD) were assessed by standard examination including blood pressure, body weight, heart rate, 12–lead electrocardiography and laboratory tests like electrolytes (Na +, K +, Ca ++, phosphate), urea, and creatinine 30 minutes before and after HD. The QT intervals and QTc QTc= QT √R-R/ (in milli seconds [ms]) for each lead were measured manually by one observer using calipers. The difference between the maximum and the minimum of QT interval was noted as QT dispersion (QT d). Results: The mean of pre and post dialysis R-R intervals was 859.22±96.85 ms and 870.43±91.45 ms, respectively (p>0.05). The mean of corrected QT cmax intervals increased significantly from 423.45±24.10 to 454.41±30.25 ms (p<0.05). The mean of QT dispersions and the corrected QT interval dispersions changed from 51.56±12.45 to 63.21±14.43 ms (p<0.05) from 59.40±13.58 to 68.33±14.55 ms (p<0.05), respectively. The changes in serum potassium and calcium levels were related with QT interval prolongation. Conclusion: QT and QTc interval and dispersion increase in HD patients. Prolonged QT interval indices had relation with K+ and Ca++ ions before but not after HD. PMID:24009942

  16. Modelling volatility recurrence intervals in the Chinese commodity futures market

    NASA Astrophysics Data System (ADS)

    Zhou, Weijie; Wang, Zhengxin; Guo, Haiming

    2016-09-01

    The law of extreme event occurrence attracts much research. The volatility recurrence intervals of Chinese commodity futures market prices are studied: the results show that the probability distributions of the scaled volatility recurrence intervals have a uniform scaling curve for different thresholds q. So we can deduce the probability distribution of extreme events from normal events. The tail of a scaling curve can be well fitted by a Weibull form, which is significance-tested by KS measures. Both short-term and long-term memories are present in the recurrence intervals with different thresholds q, which denotes that the recurrence intervals can be predicted. In addition, similar to volatility, volatility recurrence intervals also have clustering features. Through Monte Carlo simulation, we artificially synthesise ARMA, GARCH-class sequences similar to the original data, and find out the reason behind the clustering. The larger the parameter d of the FIGARCH model, the stronger the clustering effect is. Finally, we use the Fractionally Integrated Autoregressive Conditional Duration model (FIACD) to analyse the recurrence interval characteristics. The results indicated that the FIACD model may provide a method to analyse volatility recurrence intervals.

  17. The Role of Higher Harmonics In Musical Interval Perception

    NASA Astrophysics Data System (ADS)

    Krantz, Richard; Douthett, Jack

    2011-10-01

    Using an alternative parameterization of the roughness curve we make direct use of critical band results to investigate the role of higher harmonics on the perception of tonal consonance. We scale the spectral amplitudes in the complex home tone and complex interval tone to simulate acoustic signals of constant energy. Our analysis reveals that even with a relatively small addition of higher harmonics the perfect fifth emerges as a consonant interval with more, musically important, just intervals emerging as consonant as more and more energy is shifted into higher frequencies.

  18. Fixed-interval behavior maintained by conditioned reinforcement.

    PubMed

    De Lorge, J

    1967-05-01

    The key-pecking of a pigeon was reinforced with grain on an 18-min second-order schedule. During the 18 min, a key peck which completed a 3-min fixed interval produced a stimulus of 0.5-sec duration. The first 3-min fixed interval completed after 18 min resulted in primary reinforcement. Behavior characteristic of fixed-interval schedules was produced on both the 3-min components and the 18-min schedule. This performance was shown to be enhanced whenever the 0.5-sec stimulus was also presented before the presentation of grain.

  19. Unpacking a time interval lengthens its perceived temporal distance

    PubMed Central

    Liu, Yang; Li, Shu; Sun, Yan

    2014-01-01

    In quantity estimation, people often perceive that the whole is less than the sum of its parts. The current study investigated such an unpacking effect in temporal distance judgment. Our results showed that participants in the unpacked condition judged a given time interval longer than those in the packed condition, even the time interval was kept constant between the two conditions. Furthermore, this unpacking effect persists regardless of the unpacking ways we employed. Results suggest that unpacking a time interval may be a good strategy for lengthening its perceived temporal distance. PMID:25477854

  20. An evolutionary algorithm for interval solid transportation problems.

    PubMed

    Jiménez, F; Verdegay, J L

    1999-01-01

    The Solid Transportation Problem arises when bounds are given on three item properties. Usually, these properties are source, destination and mode of transport (conveyance), and may be given in an interval way. This paper deals with solid transportation problems in which the data in the constraint set are expressed in an interval form, i.e. when sources, destinations and conveyances have interval values instead of point values. An arbitrary linear or nonlinear objective function is also considered. To solve the problem, an Evolutionary Algorithm which extends and generalizes other approaches considering only point values, is proposed.

  1. Concept of Operations for Interval Management Arrivals and Approach

    NASA Technical Reports Server (NTRS)

    Hicok, Daniel S.; Barmore, Bryan E.

    2016-01-01

    This paper presents the concept of operations for interval management operations to be deployed in the US National Airspace System (NAS) by the Federal Aviation Administration (FAA) after 2020. The use of interval management operations is described that begin in en route airspace and continue to a termination point inside the arrival terminal area, in a terminal environment that includes other arrival management tools such as arrival metering, Ground-based Interval Management - Spacing (GIM-S), and Terminal Sequencing and Spacing (TSAS). The roles of Air Traffic Controllers and Flight Crews and the ground automation tools that are used by Air Traffic Controllers to enable the primary operation and variations are described.

  2. Detectability of auditory signals presented without defined observation intervals

    NASA Technical Reports Server (NTRS)

    Watson, C. S.; Nichols, T. L.

    1976-01-01

    Ability to detect tones in noise was measured without defined observation intervals. Latency density functions were estimated for the first response following a signal and, separately, for the first response following randomly distributed instances of background noise. Detection performance was measured by the maximum separation between the cumulative latency density functions for signal-plus-noise and for noise alone. Values of the index of detectability, estimated by this procedure, were approximately those obtained with a 2-dB weaker signal and defined observation intervals. Simulation of defined- and non-defined-interval tasks with an energy detector showed that this device performs very similarly to the human listener in both cases.

  3. Estimation of confidence intervals for federal waterfowl harvest surveys

    USGS Publications Warehouse

    Geissler, P.H.

    1990-01-01

    I developed methods of estimating confidence intervals for the federal waterfowl harvest surveys conducted by the U.S. Fish and Wildlife Service (USFWS). I estimated flyway harvest confidence intervals for mallards (Anas platyrhynchos) (95% CI are .+-. 8% of the estimate). Canada geese (Branta canadensis) (.+-. 11%), black ducks (Anas rubripes) (.+-. 16%), canvasbacks (Aythya valisineria) (.+-. 32%), snow geese (Chen caerulescens) (.+-. 43%), and brant (Branta bernicla) (.+-. 46%). Differences between annual estimate of 10, 13, 22, 42, 43, and 58% could be detected with mallards, Canada geese, black ducks, canvasbacks, snow geese, and brant, respectively. Estimated confidence intervals for state harvests tended to be much larger than those for the flyway estimates.

  4. Unpacking a time interval lengthens its perceived temporal distance.

    PubMed

    Liu, Yang; Li, Shu; Sun, Yan

    2014-01-01

    In quantity estimation, people often perceive that the whole is less than the sum of its parts. The current study investigated such an unpacking effect in temporal distance judgment. Our results showed that participants in the unpacked condition judged a given time interval longer than those in the packed condition, even the time interval was kept constant between the two conditions. Furthermore, this unpacking effect persists regardless of the unpacking ways we employed. Results suggest that unpacking a time interval may be a good strategy for lengthening its perceived temporal distance. PMID:25477854

  5. A new method for wavelength interval selection that intelligently optimizes the locations, widths and combinations of the intervals.

    PubMed

    Deng, Bai-Chuan; Yun, Yong-Huan; Ma, Pan; Lin, Chen-Chen; Ren, Da-Bing; Liang, Yi-Zeng

    2015-03-21

    In this study, a new algorithm for wavelength interval selection, known as interval variable iterative space shrinkage approach (iVISSA), is proposed based on the VISSA algorithm. It combines global and local searches to iteratively and intelligently optimize the locations, widths and combinations of the spectral intervals. In the global search procedure, it inherits the merit of soft shrinkage from VISSA to search the locations and combinations of informative wavelengths, whereas in the local search procedure, it utilizes the information of continuity in spectroscopic data to determine the widths of wavelength intervals. The global and local search procedures are carried out alternatively to realize wavelength interval selection. This method was tested using three near infrared (NIR) datasets. Some high-performing wavelength selection methods, such as synergy interval partial least squares (siPLS), moving window partial least squares (MW-PLS), competitive adaptive reweighted sampling (CARS), genetic algorithm PLS (GA-PLS) and interval random frog (iRF), were used for comparison. The results show that the proposed method is very promising with good results both on prediction capability and stability. The MATLAB codes for implementing iVISSA are freely available on the website: .

  6. Weibull distribution based on maximum likelihood with interval inspection data

    NASA Technical Reports Server (NTRS)

    Rheinfurth, M. H.

    1985-01-01

    The two Weibull parameters based upon the method of maximum likelihood are determined. The test data used were failures observed at inspection intervals. The application was the reliability analysis of the SSME oxidizer turbine blades.

  7. Simulation of Interval Censored Data in Medical and Biological Studies

    NASA Astrophysics Data System (ADS)

    Kiani, Kaveh; Arasan, Jayanthi

    This research looks at the simulation of interval censored data when the survivor function of the survival time is known and attendance probability of the subjects for follow-ups can take any number between 0 to 1. Interval censored data often arise in the medical and biological follow-up studies where the event of interest occurs somewhere between two known times. Regardless of the methods used to analyze these types of data, simulation of interval censored data is an important and challenging step toward model building and prediction of survival time. The simulation itself is rather tedious and very computer intensive due to the interval monitoring of subjects at prescheduled times and subject's incomplete attendance to follow-ups. In this paper the simulated data by the proposed method were assessed using the bias, standard error and root mean square error (RMSE) of the parameter estimates where the survival time T is assumed to follow the Gompertz distribution function.

  8. Baseline Bone Mineral Density Measurements Key to Future Testing Intervals

    MedlinePlus

    ... on Research 2012 May 2012 (historical) Baseline Bone Mineral Density Measurements Key to Future Testing Intervals How often a woman should have bone mineral density (BMD) tests to track bone mass is ...

  9. Concept of Operations for Interval Management Arrivals and Approach

    NASA Technical Reports Server (NTRS)

    Hicok, Daniel S.; Barmore, Bryan E.

    2016-01-01

    This paper presents the concept of operations for interval management operations to be deployed in the US National Airspace System (NAS) by the Federal Aviation Administration (FAA) Interval Management Program. The arrivals and approach operations are explored in detail including the primary operation and variations. The use of interval management operations is described that begin in en route airspace and continue to a termination point inside the arrival terminal area in the highly automated terminal environment that includes other arrival management tools such as arrival metering, Ground-based Interval Management - Spacing (GIM-S), and Terminal Sequencing and Spacing (TSAS). The roles of Air Traffic and Pilots and the ground automation tools that are used by Air Traffic Controllers to enable the operations are explored.

  10. A new interval optimization method considering tolerance design

    NASA Astrophysics Data System (ADS)

    Jiang, C.; Xie, H. C.; Zhang, Z. G.; Han, X.

    2015-12-01

    This study considers the design variable uncertainty in the actual manufacturing process for a product or structure and proposes a new interval optimization method based on tolerance design, which can provide not only an optimal design but also the allowable maximal manufacturing errors that the design can bear. The design variables' manufacturing errors are depicted using the interval method, and an interval optimization model for the structure is constructed. A dimensionless design tolerance index is defined to describe the overall uncertainty of all design variables, and by combining the nominal objective function, a deterministic two-objective optimization model is built. The possibility degree of interval is used to represent the reliability of the constraints under uncertainty, through which the model is transformed to a deterministic optimization problem. Three numerical examples are investigated to verify the effectiveness of the present method.

  11. Symbol lock detection implemented with nonoverlapping integration intervals

    NASA Technical Reports Server (NTRS)

    Shihabi, Mazen M. (Inventor); Hinedi, Sami M. (Inventor); Shah, Biren N. (Inventor)

    1995-01-01

    A symbol lock detector is introduced for an incoming coherent digital communication signal which utilizes a subcarrier modulated with binary symbol data, d(sub k), and known symbol interval T by integrating binary values of the signal over nonoverlapping first and second intervals selected to be T/2, delaying the first integral an interval T/2, and either summing or multiplying the second integral with the first one that preceded it to form a value X(sub k). That value is then averaged over a number M of symbol intervals to produce a static value Y. A symbol lock decision can then be made when the static value Y exceeds a threshold level delta.

  12. Experimental uncertainty estimation and statistics for data having interval uncertainty.

    SciTech Connect

    Kreinovich, Vladik (Applied Biomathematics, Setauket, New York); Oberkampf, William Louis (Applied Biomathematics, Setauket, New York); Ginzburg, Lev (Applied Biomathematics, Setauket, New York); Ferson, Scott (Applied Biomathematics, Setauket, New York); Hajagos, Janos (Applied Biomathematics, Setauket, New York)

    2007-05-01

    This report addresses the characterization of measurements that include epistemic uncertainties in the form of intervals. It reviews the application of basic descriptive statistics to data sets which contain intervals rather than exclusively point estimates. It describes algorithms to compute various means, the median and other percentiles, variance, interquartile range, moments, confidence limits, and other important statistics and summarizes the computability of these statistics as a function of sample size and characteristics of the intervals in the data (degree of overlap, size and regularity of widths, etc.). It also reviews the prospects for analyzing such data sets with the methods of inferential statistics such as outlier detection and regressions. The report explores the tradeoff between measurement precision and sample size in statistical results that are sensitive to both. It also argues that an approach based on interval statistics could be a reasonable alternative to current standard methods for evaluating, expressing and propagating measurement uncertainties.

  13. Antipsychotic Polypharmacy and Corrected QT Interval: A Systematic Review

    PubMed Central

    Takeuchi, Hiroyoshi; Suzuki, Takefumi; Remington, Gary; Uchida, Hiroyuki

    2015-01-01

    Objective: It remains unclear whether antipsychotic polypharmacy, a common clinical practice, is related to an increased risk of corrected time between start of Q wave and end of T wave (QTc) interval prolongation. We conducted a systematic review of the literature to address this important issue. Method: A systematic literature search was conducted in October 2014, using MEDLINE, Embase, and PsycINFO. Studies and case reports were included if they reported QTc intervals or QTc interval changes before and after antipsychotic polypharmacy or QTc intervals in both antipsychotic polypharmacy and monotherapy groups. Results: A total of 21 articles (10 clinical trials, 4 observational studies, and 7 case reports) met inclusion criteria. The clinical trials have shown that a combination treatment with risperidone or pimozide is not obviously related to an increase in QTc interval, whereas ziprasidone or sertindole combined with clozapine may prolong QTc interval. Among the 4 observational studies, antipsychotic polypharmacy was not clearly associated with QTc prolongation in 3 studies, each cross-sectional. In contrast, one prospective study showed a significant increase in QTc interval following antipsychotic coadministration. The case reports indicated an increased risk of QTc prolongation in at least some patients receiving antipsychotic polypharmacy. Conclusions: Currently available evidence fails to confirm that antipsychotic polypharmacy worsens QTc prolongation in general, although the evidence is scarce and inconsistent. Clinicians are advised to remain conservative in resorting to antipsychotic polypharmacy, as a combination of some QTc-prolongation liable antipsychotics may further prolong QTc interval, and efficacy supporting the clinical benefits of antipsychotic polypharmacy is equivocal, at best. PMID:26174525

  14. Use of systolic time intervals in studying hypertension.

    PubMed

    Tarazi, R C; Ibrahim, M M; Dustan, H P; Bravo, E L

    1976-01-01

    Systolic time intervals were measured in 54 hypertensive patients divided into three groups according to severity of hypertension, variability of blood pressure levels and presence or absence of a hyperkinetic heart. The three groups were: borderline hypertension (BLH), fixed essential hypertension (FEH) and hyperkinetic essential hypertension (HEH). Systolic time intervals (STI) provided information indicating an increased cardioadrenergic drive in BLH and HEH. This was supported by finding that propranolol abolished the increased contractility found at rest in BLH and HEH.

  15. QT interval and dispersion in primary autonomic failure.

    PubMed Central

    Lo, S. S.; Mathias, C. J.; Sutton, M. S.

    1996-01-01

    OBJECTIVE: To investigate the role of the autonomic nervous system in determining QT interval and dispersion. PATIENTS AND METHODS: 32 patients with chronic primary (idiopathic) autonomic failure (19 men, mean age 60 years) and 21 normal controls (11 men, mean age 59) without symptoms of ischaemic heart disease were studied retrospectively. Autonomic failure was diagnosed by a combination of symptomatic postural hypotension, subnormal plasma noradrenaline response to head-up tilt, and abnormal cardiovascular responses to standing, Valsalva manoeuvre, mental stress, cutaneous cold, isometric exercise, and deep breathing. QT intervals were measured from surface electrocardiograms and QT dispersion was defined as maximum QT--minimum QT occurring in any of the 12 leads. RESULTS: Mean heart rate (RR intervals) was similar in patients with autonomic failure and controls (S2 lead: 865 (132) v 857 (108) ms, P = NS; V2 lead: 865 (130) v 868 (113) ms, P = NS). QT intervals measured from electrocardiogram leads S2 and V2 were significantly longer in patients than in controls (401 (40) v 376 (16) ms, P < 0.01; and 403 (41) v 381 (20) ms, P < 0.05 respectively). The mean maximum QT interval in any lead, which is the best estimate of the maximum duration of electrical systole, was significantly longer in the patients than in controls (417 (48) v 388 (23) ms, P < 0.005). Linear regression analysis of QT and RR intervals for both groups showed a significant difference between the slopes of the two regression lines (F = 8.4, P < 0.001). However, QT dispersions were similar between patients and controls. CONCLUSIONS: Patients with primary autonomic failure have prolongation of QT intervals, indicating that the autonomic nervous system is an important determinant of QT interval. However, QT dispersion does not seem to be affected by chronic primary autonomic denervation. PMID:8665344

  16. Anaesthetists' knowledge of the QT interval in a teaching hospital.

    PubMed

    Marshall, S D; Myles, P S

    2005-12-01

    Many drugs used in anaesthesia may prolong the QT interval of the electrocardiogram (ECG), and recent U.S. Food and Drug Administration guidelines mandate monitoring of the ECG before, during and after droperidol administration. We surveyed 41 trainee and consultant anaesthetists in our Department to determine current practice and knowledge of the QT interval to investigate if this is a practical proposition. A response rate of 98% (40/41) was obtained. The majority of respondents expressed moderate to high levels of confidence in interpreting the ECG, and this was related to years of training (rho 0.36, P=0.024). A total of 27 respondents (65%) were able to correctly identify the QT interval on a schematic representation of the ECG, trainees 70% vs consultants 60%, P=0.51. When asked to name drugs that altered the QT interval, droperidol was included by 11 of the 40 respondents (28%); trainees 10% vs consultants 45%, OR 7.4 (95% CI: 1.3-41), P=0.013. Torsades de Pointes was correctly identified as a possible consequence of a prolonged QT interval by 65% of trainees and 70% of consultants, P=0.83. The results suggest that QT interval measurement is not widely practised by anaesthetists, although its clinical significance is well known, and interpretation would be unreliable without further education.

  17. Landslide occurrences and recurrence intervals of heavy rainfalls in Japan

    NASA Astrophysics Data System (ADS)

    Saito, H.; Uchida, T.; Matsuyama, H.; Korup, O.

    2015-12-01

    Dealing with predicted increases in extreme weather conditions due to climate change requires robust knowledge about controls on rainfall-triggered landslides. This study developed the probable rainfall database from weather radar data, and analyzed the potential correlation between the landslide magnitude-frequency and the recurrence interval of the heavy rainfall across Japan. We analyzed 4,744 rainfall-induced landslides (Saito et al., 2014, Geology), 1 to 72 h rainfalls, and soil water index (SWI). We then estimated recurrence intervals for these rainfall parameters using a Gumbel distribution with jackknife fitting. Results showed that the recurrence intervals of rainfall events which caused landslides (<10^3 m^3) were less than 10 yr across Japan. The recurrence intervals increased with increases in landslide volumes. With regard to the landslides larger than 10^5 m^3, recurrence intervals of the rainfall events were more than 100 yr. These results suggest that recurrence intervals of heavy rainfalls are important for assessing regional landslide hazard in Japan.

  18. Confidence Intervals for Error Rates Observed in Coded Communications Systems

    NASA Astrophysics Data System (ADS)

    Hamkins, J.

    2015-05-01

    We present methods to compute confidence intervals for the codeword error rate (CWER) and bit error rate (BER) of a coded communications link. We review several methods to compute exact and approximate confidence intervals for the CWER, and specifically consider the situation in which the true CWER is so low that only a handful, if any, codeword errors are able to be simulated. In doing so, we answer the question of how long an error-free simulation must be run in order to certify that a given CWER requirement is met with a given level of confidence, and discuss the bias introduced by aborting a simulation after observing the first codeword error. Next, we turn to the lesser studied problem of determining confidence intervals for the BER of coded systems. Since bit errors in systems that use coding or higher-order modulation do not occur independently, blind application of a method that assumes independence leads to inappropriately narrow confidence intervals. We present a new method to compute the confidence interval properly, using the first and second sample moments of the number of bit errors per codeword. This is the first method we know of to compute a confidence interval for the BER of a coded or higher-order modulation system.

  19. Procrastination by pigeons with fixed-interval response requirements.

    PubMed

    Mazur, J E

    1998-03-01

    Two experiments studied the phenomenon of procrastination, in which pigeons chose a larger, more delayed response requirement over a smaller, more immediate response requirement. The response requirements were fixed-interval schedules that did not lead to an immediate food reinforcer, but that interrupted a 55-s period in which food was delivered at random times. The experiments used an adjusting-delay procedure in which the delay to the start of one fixed-interval requirement was varied over trials to estimate an indifference point--a delay at which the two alternatives were chosen about equally often. Experiment 1 found that as the delay to a shorter fixed-interval requirement was increased, the adjusting delay to a longer fixed-interval requirement also increased, and the rate of increase depended on the duration of the longer fixed-interval requirement. Experiment 2 found a strong preference for a fixed delay of 10 s to the start of a fixed-interval requirement compared to a mixed delay of either 0 or 20 s. The results help to distinguish among different equations that might describe the decreasing effectiveness of a response requirement with increasing delay, and they suggest that delayed reinforcers and delayed response requirements have symmetrical but opposite effects on choice.

  20. Electrocardiographic Abnormalities and QTc Interval in Patients Undergoing Hemodialysis

    PubMed Central

    Nie, Yuxin; Zou, Jianzhou; Liang, Yixiu; Shen, Bo; Liu, Zhonghua; Cao, Xuesen; Chen, Xiaohong; Ding, Xiaoqiang

    2016-01-01

    Background Sudden cardiac death is one of the primary causes of mortality in chronic hemodialysis (HD) patients. Prolonged QTc interval is associated with increased rate of sudden cardiac death. The aim of this article is to assess the abnormalities found in electrocardiograms (ECGs), and to explore factors that can influence the QTc interval. Methods A total of 141 conventional HD patients were enrolled in this study. ECG tests were conducted on each patient before a single dialysis session and 15 minutes before the end of dialysis session (at peak stress). Echocardiography tests were conducted before dialysis session began. Blood samples were drawn by phlebotomy immediately before and after the dialysis session. Results Before dialysis, 93.62% of the patients were in sinus rhythm, and approximately 65% of the patients showed a prolonged QTc interval (i.e., a QTc interval above 440 ms in males and above 460ms in females). A comparison of ECG parameters before dialysis and at peak stress showed increases in heart rate (77.45±11.92 vs. 80.38±14.65 bpm, p = 0.001) and QTc interval (460.05±24.53 ms vs. 470.93±24.92 ms, p<0.001). After dividing patients into two groups according to the QTc interval, lower pre-dialysis serum concentrations of potassium (K+), calcium (Ca2+), phosphorus, calcium* phosphorus (Ca*P), and higher concentrations of plasma brain natriuretic peptide (BNP) were found in the group with prolonged QTc intervals. Patients in this group also had a larger left atrial diameter (LAD) and a thicker interventricular septum, and they tended to be older than patients in the other group. Then patients were divided into two groups according to ΔQTc (ΔQTc = QTc peak-stress- QTc pre-HD). When analyzing the patients whose QTc intervals were longer at peak stress than before HD, we found that they had higher concentrations of Ca2+ and P5+ and lower concentrations of K+, ferritin, UA, and BNP. They were also more likely to be female. In addition, more cardiac

  1. Drug-induced QT interval prolongation and torsades de pointes

    PubMed Central

    Tisdale, James E.

    2016-01-01

    Torsades de pointes (TdP) is a life-threatening arrhythmia associated with prolongation of the corrected QT (QTc) interval on the electrocardiogram. More than 100 drugs available in Canada, including widely used antibiotics, antidepressants, cardiovascular drugs and many others, may cause QTc interval prolongation and TdP. Risk factors for TdP include QTc interval >500 ms, increase in QTc interval ≥60 ms from the pretreatment value, advanced age, female sex, acute myocardial infarction, heart failure with reduced ejection fraction, hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, treatment with diuretics and elevated plasma concentrations of QTc interval–prolonging drugs due to drug interactions, inadequate dose adjustment of renally eliminated drugs in patients with kidney disease and rapid intravenous administration. Pharmacokinetic drug interactions associated with the highest risk of TdP include antifungal agents, macrolide antibiotics (except azithromycin) and drugs to treat human immunodeficiency virus interacting with amiodarone, disopyramide, dofetilide or pimozide. Other important pharmacokinetic interactions include antidepressants (bupropion, duloxetine, fluoxetine, paroxetine) interacting with flecainide, quinidine or thioridazine. Pharmacists play an important role in minimizing the risk of drug-induced QTc interval prolongation and TdP through knowledge of drugs that are associated with a known or possible risk of TdP, individualized assessment of risk of drug-induced QTc interval prolongation, awareness of drug interactions most likely to result in TdP and attention to dose reduction of renally eliminated QTc interval-prolonging drugs in patients with kidney disease. Treatment of hemodynamically stable TdP consists of discontinuation of the offending drug(s), correction of electrolyte abnormalities and administration of intravenous magnesium sulfate 1 to 2 g. PMID:27212965

  2. Interval timer control of puberty in photoinhibited Siberian hamsters.

    PubMed

    Park, Jin Ho; Kauffman, Alexander S; Paul, Matthew J; Butler, Matthew P; Beery, Annaliese K; Costantini, Ruth M; Zucker, Irving

    2006-10-01

    Puberty, which is markedly delayed in male Siberian hamsters (Phodopus sungorus) born into short day lengths, is controlled by an interval timer regulated by the duration of nocturnal melatonin secretion. Properties of the interval timer were assessed by perturbing normal patterns of melatonin secretion in males gestated and maintained thereafter in 1 of 2 short day lengths, 10 h light/day (10 L) or 12L. Melatonin secretion of short-day hamsters was suppressed by constant light treatment or modified by daily injection of propranolol to mimic nocturnal melatonin durations typical of long-day hamsters. Constant light treatment during weeks 3 to 5 induced early incomplete gonadal growth in 12L but not 10 L hamsters but did not affect late onset of gonadal development indicative of puberty in either photoperiod. Propranolol treatment during postnatal weeks 3 to 5 induced transient growth of the testes and ultimately delayed the timing of puberty by 3 weeks. Similar treatments between weeks 5 and 7 or on alternate weeks for 24 weeks did not affect the interval timer. The first 2 weeks after weaning may constitute a critical period during which the interval timer is highly responsive to photoperiod. Alternatively, the hamsters' photoperiodic history rather than age or developmental stage may be the critical variable. The interpolation of long-day melatonin signals at the time of weaning does not appear to reset the interval timer to its zero position but may reduce timer responsiveness to long-day melatonin signals several weeks later.

  3. A tuned-trace theory of interval-timing dynamics.

    PubMed

    Staddon, J E R; Chelaru, I M; Higa, J J

    2002-01-01

    Animals on interval schedules of reinforcement can rapidly adjust a temporal dependent variable, such as wait time, to changes in the prevailing interreinforcement interval. We describe data on the effects of impulse, step, sine-cyclic, and variable-interval schedules and show that they can be explained by a tuned-trace timing model with a one-back threshold-setting rule. The model can also explain steady-state timing properties such as proportional and Weber law timing and the effects of reinforcement magnitude. The model assumes that food reinforcers and other time markers have a decaying effect (trace) with properties that can be derived from the rate-sensitive property of habituation (the multiple-time-scale model). In timing experiments, response threshold is determined by the trace value at the time of the most recent reinforcement. The model provides a partial account for the learning of multiple intervals, but does not account for scalloping and other postpause features of responding on interval schedules and has some problems with square-wave schedules.

  4. Application of Interval Predictor Models to Space Radiation Shielding

    NASA Technical Reports Server (NTRS)

    Crespo, Luis G.; Kenny, Sean P.; Giesy,Daniel P.; Norman, Ryan B.; Blattnig, Steve R.

    2016-01-01

    This paper develops techniques for predicting the uncertainty range of an output variable given input-output data. These models are called Interval Predictor Models (IPM) because they yield an interval valued function of the input. This paper develops IPMs having a radial basis structure. This structure enables the formal description of (i) the uncertainty in the models parameters, (ii) the predicted output interval, and (iii) the probability that a future observation would fall in such an interval. In contrast to other metamodeling techniques, this probabilistic certi cate of correctness does not require making any assumptions on the structure of the mechanism from which data are drawn. Optimization-based strategies for calculating IPMs having minimal spread while containing all the data are developed. Constraints for bounding the minimum interval spread over the continuum of inputs, regulating the IPMs variation/oscillation, and centering its spread about a target point, are used to prevent data over tting. Furthermore, we develop an approach for using expert opinion during extrapolation. This metamodeling technique is illustrated using a radiation shielding application for space exploration. In this application, we use IPMs to describe the error incurred in predicting the ux of particles resulting from the interaction between a high-energy incident beam and a target.

  5. Physiological responses to an acute bout of sprint interval cycling.

    PubMed

    Freese, Eric C; Gist, Nicholas H; Cureton, Kirk J

    2013-10-01

    Sprint interval training has been shown to improve skeletal muscle oxidative capacity, V[Combining Dot Above]O2max, and health outcomes. However, the acute physiological responses to 4-7 maximal effort intervals have not been determined. To determine the V[Combining Dot Above]O2, cardiorespiratory responses, and energy expenditure during an acute bout of sprint interval cycling (SIC), health, college-aged subjects, 6 men and 6 women, completed 2 SIC sessions with at least 7 days between trials. Sprint interval cycling was performed on a cycle ergometer and involved a 5-minute warm-up followed by four 30-second all-out sprints with 4-minute active recovery. Peak oxygen uptake (ml·kg·min) during the 4 sprints were 35.3 ± 8.2, 38.8 ± 10.1, 38.8 ± 10.6, and 36.8 ± 9.3, and peak heart rate (b·min) were 164 ± 17, 172 ± 10, 177 ± 12, and 175 ± 22. We conclude that an acute bout of SIC elicits submaximal V[Combining Dot Above]O2 and cardiorespiratory responses during each interval that are above 80% of estimated maximal values. Although the duration of exercise in SIC is very short, the high level of V[Combining Dot Above]O2 and cardiorespiratory responses are sufficient to potentially elicit adaptations to training associated with elevated aerobic energy demand.

  6. Interval Management: Development and Implementation of an Airborne Spacing Concept

    NASA Technical Reports Server (NTRS)

    Barmore, Bryan E.; Penhallegon, William J.; Weitz, Lesley A.; Bone, Randall S.; Levitt, Ian; Flores Kriegsfeld, Julia A.; Arbuckle, Doug; Johnson, William C.

    2016-01-01

    Interval Management is a suite of ADS-B-enabled applications that allows the air traffic controller to instruct a flight crew to achieve and maintain a desired spacing relative to another aircraft. The flight crew, assisted by automation, manages the speed of their aircraft to deliver more precise inter-aircraft spacing than is otherwise possible, which increases traffic throughput at the same or higher levels of safety. Interval Management has evolved from a long history of research and is now seen as a core NextGen capability. With avionics standards recently published, completion of an Investment Analysis Readiness Decision by the FAA, and multiple flight tests planned, Interval Management will soon be part of everyday use in the National Airspace System. Second generation, Advanced Interval Management capabilities are being planned to provide a wider range of operations and improved performance and benefits. This paper briefly reviews the evolution of Interval Management and describes current development and deployment plans. It also reviews concepts under development as the next generation of applications.

  7. Interval process model and non-random vibration analysis

    NASA Astrophysics Data System (ADS)

    Jiang, C.; Ni, B. Y.; Liu, N. Y.; Han, X.; Liu, J.

    2016-07-01

    This paper develops an interval process model for time-varying or dynamic uncertainty analysis when information of the uncertain parameter is inadequate. By using the interval process model to describe a time-varying uncertain parameter, only its upper and lower bounds are required at each time point rather than its precise probability distribution, which is quite different from the traditional stochastic process model. A correlation function is defined for quantification of correlation between the uncertain-but-bounded variables at different times, and a matrix-decomposition-based method is presented to transform the original dependent interval process into an independent one for convenience of subsequent uncertainty analysis. More importantly, based on the interval process model, a non-random vibration analysis method is proposed for response computation of structures subjected to time-varying uncertain external excitations or loads. The structural dynamic responses thus can be derived in the form of upper and lower bounds, providing an important guidance for practical safety analysis and reliability design of structures. Finally, two numerical examples and one engineering application are investigated to demonstrate the feasibility of the interval process model and corresponding non-random vibration analysis method.

  8. Oxygen uptake in maximal effort constant rate and interval running.

    PubMed

    Pratt, Daniel; O'Brien, Brendan J; Clark, Bradley

    2013-01-01

    This study investigated differences in average VO2 of maximal effort interval running to maximal effort constant rate running at lactate threshold matched for time. The average VO2 and distance covered of 10 recreational male runners (VO2max: 4158 ± 390 mL · min(-1)) were compared between a maximal effort constant-rate run at lactate threshold (CRLT), a maximal effort interval run (INT) consisting of 2 min at VO2max speed with 2 minutes at 50% of VO2 repeated 5 times, and a run at the average speed sustained during the interval run (CR submax). Data are presented as mean and 95% confidence intervals. The average VO2 for INT, 3451 (3269-3633) mL · min(-1), 83% VO2max, was not significantly different to CRLT, 3464 (3285-3643) mL · min(-1), 84% VO2max, but both were significantly higher than CR sub-max, 3464 (3285-3643) mL · min(-1), 76% VO2max. The distance covered was significantly greater in CLRT, 4431 (4202-3731) metres, compared to INT and CR sub-max, 4070 (3831-4309) metres. The novel finding was that a 20-minute maximal effort constant rate run uses similar amounts of oxygen as a 20-minute maximal effort interval run despite the greater distance covered in the maximal effort constant-rate run. PMID:24288501

  9. Assessment of histological changes in antemortem gingival tissues fixed at various time intervals: A method of estimation of postmortem interval

    PubMed Central

    Mahalakshmi, V.; Gururaj, N.; Sathya, R.; Sabarinath, T. R.; Sivapathasundharam, B.; Kalaiselvan, S.

    2016-01-01

    Introduction: Conventional methods to estimate the time of death are adequate, but a histological method is yet unavailable to assess postmortem interval (PMI). The autolytic changes that occur in an unfixed antemortem gingival tissue which reflects histologically at an early stage are similar to changes that occur in postmortem tissue. These histological changes can be used and applied in a postmortem tissue as a method to assess PMI. Aims: The aim of the study is to assess the histological changes in a gingival tissue left unfixed for various time intervals and to correlate the findings with duration. Materials and Methods: Sixty gingival tissues obtained from patients following therapeutic extractions, impactions, gingivectomy and crown lengthening procedures were used. Each tissue obtained was divided into two pieces and labeled as “A”, the control group and “ B” the study group. Tissues labeled “A” were fixed in 10% formalin immediately and tissues labeled“B” were placed in closed containers and fixed after 15, 30, 45 min, 1, 2, and 4 h time interval. Of the sixty tissues in the study group “ B”, ten tissues were used for each time interval under investigation. All the fixed tissues were processed, stained, assessed, and analyzed statistically using Pearson correlation and regression analysis. Results: Histological changes appear at 15 min in an unfixed antemortem tissue. At 2 h interval, all layers with few cells in basal cell layer are involved. At 4 h interval, loss of stratification and complete homogenization of cells in the superficial layers with prominent changes in basal layer is evident. There was a positive correlation (<1.0) between the time interval and the appearance of the histological changes. Conclusion: Histological changes such as complete homogenization of cells in superficial layers and loss of epithelial architecture at 4 h in unfixed antemortem tissue may be used as a criterion to estimate PMI, after further studies

  10. Short interval expansion of Rényi entropy on torus

    NASA Astrophysics Data System (ADS)

    Chen, Bin; Wu, Jun-Bao; Zhang, Jia-ju

    2016-08-01

    We investigate the short interval expansion of the Rényi entropy for two-dimensional conformal field theory (CFT) on a torus. We require the length of the interval ℓ to be small with respect to the spatial and temporal sizes of the torus. The operator product expansion of the twist operators allows us to compute the short interval expansion of the Rényi entropy at any temperature. In particular, we pay special attention to the large c CFTs dual to the AdS3 gravity and its cousins. At both low and high temperature limits, we read the Rényi entropies to order ℓ6, and find good agreements with holographic results. Moreover, the expansion allows us to read 1 /c contribution, which is hard to get by expanding the thermal density matrix. We generalize the study to the case with the chemical potential as well.

  11. Simultaneous timing of multiple intervals: implications of the scalar property.

    PubMed

    Leak, T M; Gibbon, J

    1995-01-01

    Three experiments with pigeons are reported in which the scalar property in simultaneous timing tasks was studied. According to scalar expectancy theory, the scalar property should be maintained in simultaneous timing, but the behavioral theory of timing predicts that the scalar property should be evident only in independent timing. Experiment 1 showed that the appearance of distinct peaks at reinforcement times required about a 4:1 ratio between intervals. Experiment 2 (2-interval timing task) and Experiment 3 (3-interval timing task) used an individual trial analysis technique to examine high-rate responding segments bracketing the times of reinforcement. The standard deviations of the starting and stopping times of high-rate segments were linearly related to their means and to reinforcement time, supporting the scalar property in simultaneous timing.

  12. Atomic temporal interval relations in branching time: calculation and application

    NASA Astrophysics Data System (ADS)

    Anger, Frank D.; Ladkin, Peter B.; Rodriguez, Rita V.

    1991-03-01

    A practical method of reasoning about intervals in a branching-time model which is dense, unbounded, future-branching, without rejoining branches is presented. The discussion is based on heuristic constraint- propagation techniques using the relation algebra of binary temporal relations among the intervals over the branching-time model. This technique has been applied with success to models of intervals over linear time by Allen and others, and is of cubic-time complexity. To extend it to branding-time models, it is necessary to calculate compositions of the relations; thus, the table of compositions for the 'atomic' relations is computed, enabling the rapid determination of the composition of arbitrary relations, expressed as disjunctions or unions of the atomic relations.

  13. Magnitude estimation reveals temporal binding at super-second intervals.

    PubMed

    Humphreys, Gruffydd R; Buehner, Marc J

    2009-10-01

    Several recent studies (e.g., Haggard, Aschersleben, Gehrke, & Prinz, 2002; Haggard & Clark, 2003; Haggard, Clark, & Kalogeras, 2002) have demonstrated a "Temporal Binding" effect in which the interval between an intentional action and its consequent outcome is subjectively shorter compared to equivalent intervals that do not involve intentional action. The bulk of the literature has relied on the "Libet Clock" (Libet, Gleason, Wright, & Pearl, 1983; but see also Engbert & Wohlschläger, 2007; Engbert, Wohlschläger, Thomas, & Haggard, 2007; Engbert, Wohlschläger, & Haggard, 2008). Here we demonstrate that Temporal Binding is a robust finding that can also be reliably achieved with a Magnitude Estimation procedure, and that occurs over intervals far greater than those previously explored. Implications for the underlying mechanisms are discussed.

  14. Is it safe to program a long tachycardia detection interval?

    PubMed

    Kühlkamp, Volker; Dörnberger, Volker; Bosch, Ralph R; Kettering, Klaus; Mewis, Christian

    2002-11-01

    Implantable cardioverter defibrillator (ICD) therapy is used frequently in patients with "slow" ventricular tachycardia (VT). Hence, the tachycardia detection interval is programmed within the range of the physiologic heart rate, but this may cause serious problems. If a fast VT is converted to sinus tachycardia with a cycle length shorter than the tachycardia detection interval, the episode is not terminated and the success counter is not reset. If this happens repeatedly, therapies will be exhausted without termination of the episode. If VT recurs within such an episode, it will not be treated. This report describes a patient who died suddenly in a scenario similar to the one described. Although all documented VT/ventricular fibrillation episodes were terminated by the device, the episode was not terminated because of the ongoing supraventricular tachycardia. Therefore, no further therapies were available and the patient probably died of fast untreated VT. Programming of a long tachycardia detection interval is dangerous in currently available ICDs.

  15. Unwinding the Molecular Basis of Interval and Circadian Timing

    PubMed Central

    Agostino, Patricia V.; Golombek, Diego A.; Meck, Warren H.

    2011-01-01

    Neural timing mechanisms range from the millisecond to diurnal, and possibly annual, frequencies. Two of the main processes under study are the interval timer (seconds-to-minute range) and the circadian clock. The molecular basis of these two mechanisms is the subject of intense research, as well as their possible relationship. This article summarizes data from studies investigating a possible interaction between interval and circadian timing and reviews the molecular basis of both mechanisms, including the discussion of the contribution from studies of genetically modified animal models. While there is currently no common neurochemical substrate for timing mechanisms in the brain, circadian modulation of interval timing suggests an interaction of different frequencies in cerebral temporal processes. PMID:22022309

  16. Fast and Accurate Construction of Confidence Intervals for Heritability.

    PubMed

    Schweiger, Regev; Kaufman, Shachar; Laaksonen, Reijo; Kleber, Marcus E; März, Winfried; Eskin, Eleazar; Rosset, Saharon; Halperin, Eran

    2016-06-01

    Estimation of heritability is fundamental in genetic studies. Recently, heritability estimation using linear mixed models (LMMs) has gained popularity because these estimates can be obtained from unrelated individuals collected in genome-wide association studies. Typically, heritability estimation under LMMs uses the restricted maximum likelihood (REML) approach. Existing methods for the construction of confidence intervals and estimators of SEs for REML rely on asymptotic properties. However, these assumptions are often violated because of the bounded parameter space, statistical dependencies, and limited sample size, leading to biased estimates and inflated or deflated confidence intervals. Here, we show that the estimation of confidence intervals by state-of-the-art methods is inaccurate, especially when the true heritability is relatively low or relatively high. We further show that these inaccuracies occur in datasets including thousands of individuals. Such biases are present, for example, in estimates of heritability of gene expression in the Genotype-Tissue Expression project and of lipid profiles in the Ludwigshafen Risk and Cardiovascular Health study. We also show that often the probability that the genetic component is estimated as 0 is high even when the true heritability is bounded away from 0, emphasizing the need for accurate confidence intervals. We propose a computationally efficient method, ALBI (accurate LMM-based heritability bootstrap confidence intervals), for estimating the distribution of the heritability estimator and for constructing accurate confidence intervals. Our method can be used as an add-on to existing methods for estimating heritability and variance components, such as GCTA, FaST-LMM, GEMMA, or EMMAX. PMID:27259052

  17. High-Intensity Interval Exercise and Postprandial Triacylglycerol.

    PubMed

    Burns, Stephen F; Miyashita, Masashi; Stensel, David J

    2015-07-01

    This review examined if high-intensity interval exercise (HIIE) reduces postprandial triacylglycerol (TAG) levels. Fifteen studies were identified, in which the effect of interval exercise conducted at an intensity of >65% of maximal oxygen uptake was evaluated on postprandial TAG levels. Analysis was divided between studies that included supramaximal exercise and those that included submaximal interval exercise. Ten studies examined the effect of a single session of low-volume HIIE including supramaximal sprints on postprandial TAG. Seven of these studies noted reductions in the postprandial total TAG area under the curve the morning after exercise of between ~10 and 21% compared with rest, but three investigations found no significant difference in TAG levels. Variations in the HIIE protocol used, inter-individual variation or insufficient time post-exercise for an increase in lipoprotein lipase activity are proposed reasons for the divergent results among studies. Five studies examined the effect of high-volume submaximal interval exercise on postprandial TAG. Four of these studies were characterised by high exercise energy expenditure and effectively attenuated total postprandial TAG levels by ~15-30%, but one study with a lower energy expenditure found no effect on TAG. The evidence suggests that supramaximal HIIE can induce large reductions in postprandial TAG levels but findings are inconsistent. Submaximal interval exercise offers no TAG metabolic or time advantage over continuous aerobic exercise but could be appealing in nature to some individuals. Future research should examine if submaximal interval exercise can reduce TAG levels in line with more realistic and achievable exercise durations of 30 min per day.

  18. Persistent Fluctuations in Stride Intervals under Fractal Auditory Stimulation

    PubMed Central

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

    2014-01-01

    Stride sequences of healthy gait are characterized by persistent long-range correlations, which become anti-persistent in the presence of an isochronous metronome. The latter phenomenon is of particular interest because auditory cueing is generally considered to reduce stride variability and may hence be beneficial for stabilizing gait. Complex systems tend to match their correlation structure when synchronizing. In gait training, can one capitalize on this tendency by using a fractal metronome rather than an isochronous one? We examined whether auditory cues with fractal variations in inter-beat intervals yield similar fractal inter-stride interval variability as isochronous auditory cueing in two complementary experiments. In Experiment 1, participants walked on a treadmill while being paced by either an isochronous or a fractal metronome with different variation strengths between beats in order to test whether participants managed to synchronize with a fractal metronome and to determine the necessary amount of variability for participants to switch from anti-persistent to persistent inter-stride intervals. Participants did synchronize with the metronome despite its fractal randomness. The corresponding coefficient of variation of inter-beat intervals was fixed in Experiment 2, in which participants walked on a treadmill while being paced by non-isochronous metronomes with different scaling exponents. As expected, inter-stride intervals showed persistent correlations similar to self-paced walking only when cueing contained persistent correlations. Our results open up a new window to optimize rhythmic auditory cueing for gait stabilization by integrating fractal fluctuations in the inter-beat intervals. PMID:24651455

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

    PubMed

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

    2014-01-01

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

  20. Reference intervals for serum creatine kinase in athletes

    PubMed Central

    Mougios, Vassilis

    2007-01-01

    Background The serum concentration of creatine kinase (CK) is used widely as an index of skeletal muscle fibre damage in sport and exercise. Since athletes have higher CK values than non‐athletes, comparing the values of athletes to the normal values established in non‐athletes is pointless. The purpose of this study was to introduce reference intervals for CK in athletes. Method CK was assayed in serum samples from 483 male athletes and 245 female athletes, aged 7–44. Samples had been obtained throughout the training and competition period. For comparison, CK was also assayed in a smaller number of non‐athletes. Reference intervals (2.5th to 97.5th percentile) were calculated by the non‐parametric method. Results The reference intervals were 82–1083 U/L (37°C) in male and 47–513 U/L in female athletes. The upper reference limits were twice the limits reported for moderately active non‐athletes in the literature or calculated in the non‐athletes in this study. The upper limits were up to six times higher than the limits reported for inactive individuals in the literature. When reference intervals were calculated specifically in male football (soccer) players and swimmers, a threefold difference in the upper reference limit was found (1492 vs 523 U/L, respectively), probably resulting from the different training and competition demands of the two sports. Conclusion Sport training and competition have profound effects on the reference intervals for serum CK. Introducing sport‐specific reference intervals may help to avoid misinterpretation of high values and to optimise training. PMID:17526622

  1. An interval logic for higher-level temporal reasoning

    NASA Technical Reports Server (NTRS)

    Schwartz, R. L.; Melliar-Smith, P. M.; Vogt, F. H.; Plaisted, D. A.

    1983-01-01

    Prior work explored temporal logics, based on classical modal logics, as a framework for specifying and reasoning about concurrent programs, distributed systems, and communications protocols, and reported on efforts using temporal reasoning primitives to express very high level abstract requirements that a program or system is to satisfy. Based on experience with those primitives, this report describes an Interval Logic that is more suitable for expressing such higher level temporal properties. The report provides a formal semantics for the Interval Logic, and several examples of its use. A description of decision procedures for the logic is also included.

  2. Systolic time interval data acquisition system. Specialized cardiovascular studies

    NASA Technical Reports Server (NTRS)

    Baker, J. T.

    1976-01-01

    The development of a data acquisition system for noninvasive measurement of systolic time intervals is described. R-R interval from the ECG determines instantaneous heart rate prior to the beat to be measured. Total electromechanical systole (Q-S2) is measured from the onset of the ECG Q-wave to the onset of the second heart sound (S2). Ejection time (ET or LVET) is measured from the onset of carotid upstroke to the incisure. Pre-ejection period (PEP) is computed by subtracting ET from Q-S2. PEP/ET ratio is computed directly.

  3. PREDICTION INTERVALS FOR INTEGRALS OF GAUSSIAN RANDOM FIELDS

    PubMed Central

    De Oliveira, Victor; Kone, Bazoumana

    2014-01-01

    Methodology is proposed for the construction of prediction intervals for integrals of Gaussian random fields over bounded regions (called block averages in the geostatistical literature) based on observations at a finite set of sampling locations. Two bootstrap calibration algorithms are proposed, termed indirect and direct, aimed at improving upon plug-in prediction intervals in terms of coverage probability. A simulation study is carried out that illustrates the effectiveness of both procedures, and these procedures are applied to estimate block averages of chromium traces in a potentially contaminated region in Switzerland. PMID:25431507

  4. Control of Angular Intervals for Angle-Multiplexed Holographic Memory

    NASA Astrophysics Data System (ADS)

    Kinoshita, Nobuhiro; Muroi, Tetsuhiko; Ishii, Norihiko; Kamijo, Koji; Shimidzu, Naoki

    2009-03-01

    In angle-multiplexed holographic memory, the full width at half maximum of the Bragg selectivity curves is dependent on the angle formed between the medium and incident laser beams. This indicates the possibility of high density and high multiplexing number by varying the angular intervals between adjacent holograms. We propose an angular interval scheduling for closely stacking holograms into medium even when the angle range is limited. We obtained bit error rates of the order of 10-4 under the following conditions: medium thickness of 1 mm, laser beam wavelength of 532 nm, and angular multiplexing number of 300.

  5. Bootstrap Confidence Intervals for Ordinary Least Squares Factor Loadings and Correlations in Exploratory Factor Analysis

    ERIC Educational Resources Information Center

    Zhang, Guangjian; Preacher, Kristopher J.; Luo, Shanhong

    2010-01-01

    This article is concerned with using the bootstrap to assign confidence intervals for rotated factor loadings and factor correlations in ordinary least squares exploratory factor analysis. Coverage performances of "SE"-based intervals, percentile intervals, bias-corrected percentile intervals, bias-corrected accelerated percentile intervals, and…

  6. The lucid interval associated with epidural bleeding: evolving understanding.

    PubMed

    Ganz, Jeremy C

    2013-04-01

    The aim of this paper was to elucidate the evolution of our understanding of the term "lucid interval." A number of texts were reviewed to assess their suitability for analysis. The primary requirement was that the text contain detailed descriptions of a series of patients. Details of the clinical course, the findings and timing of surgery, and, when relevant, the time of death and postmortem findings were required. Books written by Henri-François Le Dran, Percival Pott, and James Hill fulfilled these criteria. Surgical findings included the presence and type of fractures, changes in the bone, separation of periosteum, malodorous or purulent material, tense brain, and hematoma. Postmortem findings supplemented and/or complemented the surgical findings. The courses of the patients were then tabulated, and the correlation between different clinical and operative findings was thereby determined. Our understanding of a lucid interval began in the early 18th century with the work of Henri-François Le Dran and Percival Pott in London. They did not, however, demonstrate an interval without symptoms between trauma and deterioration in patients with epidural hematomas (EDHs). The interval they described was longer than usually expected with EDHs and occurred exclusively in patients who had a posttraumatic infection. In 1751, James Hill, from Dumfries, Scotland, described the first hematoma-related lucid interval in a patient with a subdural hematoma. The first case of a lucid interval associated with an EDH was described by John Abernethy. In the 19th century, Jonathan Hutchinson and Walter Jacobson described the interval as it is known today, in cases of EDH. The most recent work on the topic came from studies in Cincinnati and Oslo, where it was demonstrated that bleeding can separate dura mater and that hemorrhage into the epidural space can be shunted out via the veins. This shunting could delay the accumulation of a hematoma and thus the rise in intracranial pressure

  7. The lucid interval associated with epidural bleeding: evolving understanding.

    PubMed

    Ganz, Jeremy C

    2013-04-01

    The aim of this paper was to elucidate the evolution of our understanding of the term "lucid interval." A number of texts were reviewed to assess their suitability for analysis. The primary requirement was that the text contain detailed descriptions of a series of patients. Details of the clinical course, the findings and timing of surgery, and, when relevant, the time of death and postmortem findings were required. Books written by Henri-François Le Dran, Percival Pott, and James Hill fulfilled these criteria. Surgical findings included the presence and type of fractures, changes in the bone, separation of periosteum, malodorous or purulent material, tense brain, and hematoma. Postmortem findings supplemented and/or complemented the surgical findings. The courses of the patients were then tabulated, and the correlation between different clinical and operative findings was thereby determined. Our understanding of a lucid interval began in the early 18th century with the work of Henri-François Le Dran and Percival Pott in London. They did not, however, demonstrate an interval without symptoms between trauma and deterioration in patients with epidural hematomas (EDHs). The interval they described was longer than usually expected with EDHs and occurred exclusively in patients who had a posttraumatic infection. In 1751, James Hill, from Dumfries, Scotland, described the first hematoma-related lucid interval in a patient with a subdural hematoma. The first case of a lucid interval associated with an EDH was described by John Abernethy. In the 19th century, Jonathan Hutchinson and Walter Jacobson described the interval as it is known today, in cases of EDH. The most recent work on the topic came from studies in Cincinnati and Oslo, where it was demonstrated that bleeding can separate dura mater and that hemorrhage into the epidural space can be shunted out via the veins. This shunting could delay the accumulation of a hematoma and thus the rise in intracranial pressure

  8. Daily meal anticipation: interaction of circadian and interval timing.

    PubMed

    Terman, M; Gibbon, J; Fairhurst, S; Waring, A

    1984-01-01

    Both short-interval and circadian timing systems support anticipatory response accelerations prior to food reinforcement. In the first case, the behavior pattern is determined by a scalar timing process with an arbitrary-reset property. In contrast, under daily cycles of food-availability, behavior reflects a self-sustaining oscillation. With rats as subjects, the concurrent operation of timing of both kinds was studied by addition of premeal auditory cues on the circadian baseline, in the absence of a day-night illumination cycle. Cues within both minute and hour ranges served to lower the level of premeal anticipatory responding, although exponential accelerations were similar to the uncued case. Cues within the minutes range yielded interval-timing functions that reflected approximate superposition. Cues within the hours range suppressed respondings at their outset, in proportion to cue duration. When one of the shorter cues was suddenly lengthened, short-interval accelerations appeared at inappropriate circadian phases. When a premeal cue was extended through mealtime, anticipation rates increased markedly, suggesting that cue termination at the start of mealtime is a potent anchor for premeal anticipation regardless of cue duration. By use of meal-omission probes without external cues, peak rates were located after the onset of expected mealtime, often near its termination. The results suggest interactions between the scalar interval timer and the circadian anticipation timer, as modulated by the circadian free-run timer.

  9. Parametric likelihood inference for interval censored competing risks data

    PubMed Central

    Hudgens, Michael G.; Li, Chenxi

    2014-01-01

    Summary Parametric estimation of the cumulative incidence function (CIF) is considered for competing risks data subject to interval censoring. Existing parametric models of the CIF for right censored competing risks data are adapted to the general case of interval censoring. Maximum likelihood estimators for the CIF are considered under the assumed models, extending earlier work on nonparametric estimation. A simple naive likelihood estimator is also considered that utilizes only part of the observed data. The naive estimator enables separate estimation of models for each cause, unlike full maximum likelihood in which all models are fit simultaneously. The naive likelihood is shown to be valid under mixed case interval censoring, but not under an independent inspection process model, in contrast with full maximum likelihood which is valid under both interval censoring models. In simulations, the naive estimator is shown to perform well and yield comparable efficiency to the full likelihood estimator in some settings. The methods are applied to data from a large, recent randomized clinical trial for the prevention of mother-to-child transmission of HIV. PMID:24400873

  10. 30 CFR 75.360 - Preshift examination at fixed intervals.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... of any 8-hour interval during which any person is scheduled to work or travel underground. No person... pumpers are scheduled to work or travel shall not be required prior to the pumper entering the areas if... the area where the pumper works or travels. The examination of the area must be completed before...

  11. Confidence Intervals for Gamma-Family Measures of Ordinal Association

    ERIC Educational Resources Information Center

    Woods, Carol M.

    2007-01-01

    This research focused on confidence intervals (CIs) for 10 measures of monotonic association between ordinal variables. Standard errors (SEs) were also reviewed because more than 1 formula was available per index. For 5 indices, an element of the formula used to compute an SE is given that is apparently new. CIs computed with different SEs were…

  12. Mnemonic benefits of retrieval practice at short retention intervals.

    PubMed

    Rowland, Christopher A; DeLosh, Edward L

    2015-01-01

    The testing effect refers to the retention benefit conferred by prior retrieval of information from memory. Although the testing effect is a robust phenomenon, a common assumption is that reliable memory benefits only emerge after long retention intervals of days or weeks. The present study focused on potential test-induced retention benefits for brief retention intervals on the order of minutes and tens of seconds. Participants in four experiments studied lists of words. Some of the items were subjected to an initial cued recall test, and others were re-presented for additional study. Free recall tests were administered in each experiment following retention intervals ranging from 30 s to 8 min. When initial retrieval practice was successful (Experiments 1 through 3), or feedback compensated for unsuccessful retrieval (Experiment 4), significant testing effects emerged at all retention intervals. Results are discussed in the context of a bifurcated item-distribution model and highlight the importance of initial test performance and the type of analysis employed when examining testing effect data. PMID:24579674

  13. Systolic time intervals in normotensive and hypertensive human pregnancy.

    PubMed

    Lim, Y L; Walters, W A

    1976-09-01

    Systolic time intervals were measured in 10 nonpregnant, 37 normotensive, and 18 hypertensive pregnant women in both supine and lateral positions. With all the subjects in the supine position, left ventricular ejection time (LVET) was shortened; the pre-ejection period (PEP) lengthened, and the PEP/LVET ratio increased in normotensive late pregnancy compared with the nonpregnant state. Similar alterations in systolic time intervals were observed in hypertensive women in both early and late pregnancy in the supine position. In normotensive women in early pregnancy, alterations in systolic time intervals were inconclusive. When normotensive women in late pregnancy were turned from the supine into the left lateral position, a prolongation of LVET and a decrease in the PEP/LVET ratio were observed. When hypertensive women in late pregnancy adopted the left lateral position, no significant alterations in systolic time intervals occurred. Isovolumetric contraction time (ICT) was prolonged only in the hypertensive pregnant women in the supine position. The study suggests that left ventricular performance is diminished in normotensive women in late pregnancy when supine but improves when they adopt the lateral position. In addition, hypertensive pregnant women show evidence of diminished left ventricular performance which is not improved in late pregnancy by assumption of the left lateral position.

  14. Researchers Misunderstand Confidence Intervals and Standard Error Bars

    ERIC Educational Resources Information Center

    Belia, Sarah; Fidler, Fiona; Williams, Jennifer; Cumming, Geoff

    2005-01-01

    Little is known about researchers' understanding of confidence intervals (CIs) and standard error (SE) bars. Authors of journal articles in psychology, behavioral neuroscience, and medicine were invited to visit a Web site where they adjusted a figure until they judged 2 means, with error bars, to be just statistically significantly different (p…

  15. A model of interval timing by neural integration.

    PubMed

    Simen, Patrick; Balci, Fuat; de Souza, Laura; Cohen, Jonathan D; Holmes, Philip

    2011-06-22

    We show that simple assumptions about neural processing lead to a model of interval timing as a temporal integration process, in which a noisy firing-rate representation of time rises linearly on average toward a response threshold over the course of an interval. Our assumptions include: that neural spike trains are approximately independent Poisson processes, that correlations among them can be largely cancelled by balancing excitation and inhibition, that neural populations can act as integrators, and that the objective of timed behavior is maximal accuracy and minimal variance. The model accounts for a variety of physiological and behavioral findings in rodents, monkeys, and humans, including ramping firing rates between the onset of reward-predicting cues and the receipt of delayed rewards, and universally scale-invariant response time distributions in interval timing tasks. It furthermore makes specific, well-supported predictions about the skewness of these distributions, a feature of timing data that is usually ignored. The model also incorporates a rapid (potentially one-shot) duration-learning procedure. Human behavioral data support the learning rule's predictions regarding learning speed in sequences of timed responses. These results suggest that simple, integration-based models should play as prominent a role in interval timing theory as they do in theories of perceptual decision making, and that a common neural mechanism may underlie both types of behavior.

  16. Constructing Approximate Confidence Intervals for Parameters with Structural Equation Models

    ERIC Educational Resources Information Center

    Cheung, Mike W. -L.

    2009-01-01

    Confidence intervals (CIs) for parameters are usually constructed based on the estimated standard errors. These are known as Wald CIs. This article argues that likelihood-based CIs (CIs based on likelihood ratio statistics) are often preferred to Wald CIs. It shows how the likelihood-based CIs and the Wald CIs for many statistics and psychometric…

  17. Measurement of Phonated Intervals during Four Fluency-Inducing Conditions

    ERIC Educational Resources Information Center

    Davidow, Jason H.; Bothe, Anne K.; Andreatta, Richard D.; Ye, Jun

    2009-01-01

    Purpose: Previous investigations of persons who stutter have demonstrated changes in vocalization variables during fluency-inducing conditions (FICs). A series of studies has also shown that a reduction in short intervals of phonation, those from 30 to 200 ms, is associated with decreased stuttering. The purpose of this study, therefore, was to…

  18. Covering by random intervals and one-dimensional continuum percolation

    SciTech Connect

    Domb, C. )

    1989-04-01

    A brief historical introduction is given to the problem of covering a line by random overlapping intervals. The problem for equal intervals was first solved by Whitworth in the 1890s. A brief resume is given of his solution. The advantages of the present author's approach, which uses a Poisson process, are outlined, and a solution is derived by Laplace transforms. The asymptotic behavior as the line becomes long is calculated and is related to the one-dimensional continuum percolation problem. It is shown that as long as the mean interval size is finite, the probability of complete coverage decays exponentially, so that the critical percolation probability p{sub c} = 1. However, as soon as the mean interval size becomes infinite, the critical percolation probability p{sub c} switches to 0. This is in accord with previous results for a lattice model by Chinese workers, but differs from those of Schulman. A possible reason for the discrepancy is a difference in boundary conditions.

  19. Precise time and time interval data handling and reduction

    NASA Technical Reports Server (NTRS)

    Fisher, L. C.

    1973-01-01

    In the past year, the increase in Precise Time And Time Interval data to be reduced to the U.S. Naval Observatory Master Clock and the requirement for its quick dissemination has necessitated development of more efficient methods of data handling and reduction. An outline of the data involved and of the Time Service computerization of these functions is presented.

  20. A model of interval timing by neural integration

    PubMed Central

    Simen, Patrick; Balci, Fuat; deSouza, Laura; Cohen, Jonathan D.; Holmes, Philip

    2011-01-01

    We show that simple assumptions about neural processing lead to a model of interval timing as a temporal integration process, in which a noisy firing-rate representation of time rises linearly on average toward a response threshold over the course of an interval. Our assumptions include: that neural spike trains are approximately independent Poisson processes; that correlations among them can be largely cancelled by balancing excitation and inhibition; that neural populations can act as integrators; and that the objective of timed behavior is maximal accuracy and minimal variance. The model accounts for a variety of physiological and behavioral findings in rodents, monkeys and humans, including ramping firing rates between the onset of reward-predicting cues and the receipt of delayed rewards, and universally scale-invariant response time distributions in interval timing tasks. It furthermore makes specific, well-supported predictions about the skewness of these distributions, a feature of timing data that is usually ignored. The model also incorporates a rapid (potentially one-shot) duration-learning procedure. Human behavioral data support the learning rule’s predictions regarding learning speed in sequences of timed responses. These results suggest that simple, integration-based models should play as prominent a role in interval timing theory as they do in theories of perceptual decision making, and that a common neural mechanism may underlie both types of behavior. PMID:21697374

  1. [Influence of short interpregnancy interval on pregnancy outcomes].

    PubMed

    Zilberman, Beniamin

    2007-01-01

    Optimal interpregnancy interval (IPI) is an important issue affecting pregnancy results, fetal and maternal morbidity/mortality, and has economic, social and demographic significance. The definition of IPI has not yet been standardized, thereby affecting results and conclusions. It was found that pregnancies conceived 18 to 23 months after previous birth had the lowest risks of fetal complications--low birth weight, preterm birth, and small size for gestational age. Women with shorter IPI have higher risk of maternal mortality, hypertensive disorders of pregnancy, bleeding and anemia. Studies conducted in developing countries suggest longer IPI-3 to 5 years as the optimal IPI. The relation between short interpregnancy intervals and adverse perinatal outcomes has been attributed to maternal nutritional depletion, the competition theory and behavioral risk factors. It was proposed that there is a J-shaped association between IPI and adverse pregnancy outcomes. This is not the effect of other common reproductive risk factors. There is a need to inform women regarding the association between adverse pregnancy outcomes and interpregnancy intervals, as well as the benefits of optimizing that interval. Public health programs could identify women with other risk factors (for example substance abuse, such as tobacco or alcohol, or a young/advanced maternal age) for interventions to improve perinatal outcomes. There is also a need for more studies to define the optimal IPI under local conditions. PMID:17294848

  2. Retention interval affects visual short-term memory encoding.

    PubMed

    Bankó, Eva M; Vidnyánszky, Zoltán

    2010-03-01

    Humans can efficiently store fine-detailed facial emotional information in visual short-term memory for several seconds. However, an unresolved question is whether the same neural mechanisms underlie high-fidelity short-term memory for emotional expressions at different retention intervals. Here we show that retention interval affects the neural processes of short-term memory encoding using a delayed facial emotion discrimination task. The early sensory P100 component of the event-related potentials (ERP) was larger in the 1-s interstimulus interval (ISI) condition than in the 6-s ISI condition, whereas the face-specific N170 component was larger in the longer ISI condition. Furthermore, the memory-related late P3b component of the ERP responses was also modulated by retention interval: it was reduced in the 1-s ISI as compared with the 6-s condition. The present findings cannot be explained based on differences in sensory processing demands or overall task difficulty because there was no difference in the stimulus information and subjects' performance between the two different ISI conditions. These results reveal that encoding processes underlying high-precision short-term memory for facial emotional expressions are modulated depending on whether information has to be stored for one or for several seconds.

  3. Robust Confidence Interval for a Ratio of Standard Deviations

    ERIC Educational Resources Information Center

    Bonett, Douglas G.

    2006-01-01

    Comparing variability of test scores across alternate forms, test conditions, or subpopulations is a fundamental problem in psychometrics. A confidence interval for a ratio of standard deviations is proposed that performs as well as the classic method with normal distributions and performs dramatically better with nonnormal distributions. A simple…

  4. Patterns of interval correlations in neural oscillators with adaptation

    PubMed Central

    Schwalger, Tilo; Lindner, Benjamin

    2013-01-01

    Neural firing is often subject to negative feedback by adaptation currents. These currents can induce strong correlations among the time intervals between spikes. Here we study analytically the interval correlations of a broad class of noisy neural oscillators with spike-triggered adaptation of arbitrary strength and time scale. Our weak-noise theory provides a general relation between the correlations and the phase-response curve (PRC) of the oscillator, proves anti-correlations between neighboring intervals for adapting neurons with type I PRC and identifies a single order parameter that determines the qualitative pattern of correlations. Monotonically decaying or oscillating correlation structures can be related to qualitatively different voltage traces after spiking, which can be explained by the phase plane geometry. At high firing rates, the long-term variability of the spike train associated with the cumulative interval correlations becomes small, independent of model details. Our results are verified by comparison with stochastic simulations of the exponential, leaky, and generalized integrate-and-fire models with adaptation. PMID:24348372

  5. High-Intensity Interval Training for Improving Postprandial Hyperglycemia

    ERIC Educational Resources Information Center

    Little, Jonathan P.; Francois, Monique E.

    2014-01-01

    High-intensity interval training (HIIT) has garnered attention in recent years as a time-efficient exercise option for improving cardiovascular and metabolic health. New research demonstrates that HIIT may be particularly effective for improving postprandial hyperglycemia in individuals with, or at risk for, type 2 diabetes (T2D). These findings…

  6. Motor and Executive Control in Repetitive Timing of Brief Intervals

    ERIC Educational Resources Information Center

    Holm, Linus; Ullen, Fredrik; Madison, Guy

    2013-01-01

    We investigated the causal role of executive control functions in the production of brief time intervals by means of a concurrent task paradigm. To isolate the influence of executive functions on timing from motor coordination effects, we dissociated executive load from the number of effectors used in the dual task situation. In 3 experiments,…

  7. The Behavioral Economics of Choice and Interval Timing

    ERIC Educational Resources Information Center

    Jozefowiez, J.; Staddon, J. E. R.; Cerutti, D. T.

    2009-01-01

    The authors propose a simple behavioral economic model (BEM) describing how reinforcement and interval timing interact. The model assumes a Weber-law-compliant logarithmic representation of time. Associated with each represented time value are the payoffs that have been obtained for each possible response. At a given real time, the response with…

  8. Response Priming Patterns Differ with Interstimulus Interval Duration

    ERIC Educational Resources Information Center

    Spencer, Kristie A.; Wiley, Erin

    2008-01-01

    Priming paradigms make it possible to study the nature of response preparation before the onset of movement. One way to examine this process is through manipulation of the interstimulus interval (ISI). The timing of the prime and target presentation has been shown to have distinct effects on reaction time patterns, in both healthy and…

  9. Earning and Obtaining Reinforcers under Concurrent Interval Scheduling

    ERIC Educational Resources Information Center

    MacDonall, James S.

    2005-01-01

    Contingencies of reinforcement specify how reinforcers are earned and how they are obtained. Ratio contingencies specify the number of responses that earn a reinforcer, and the response satisfying the ratio requirement obtains the earned reinforcer. Simple interval schedules specify that a certain time earns a reinforcer, which is obtained by the…

  10. Confidence Interval Coverage for Cohen's Effect Size Statistic

    ERIC Educational Resources Information Center

    Algina, James; Keselman, H. J.; Penfield, Randall D.

    2006-01-01

    Kelley compared three methods for setting a confidence interval (CI) around Cohen's standardized mean difference statistic: the noncentral-"t"-based, percentile (PERC) bootstrap, and biased-corrected and accelerated (BCA) bootstrap methods under three conditions of nonnormality, eight cases of sample size, and six cases of population effect size…

  11. Confidence Intervals for Assessing Heterogeneity in Generalized Linear Mixed Models

    ERIC Educational Resources Information Center

    Wagler, Amy E.

    2014-01-01

    Generalized linear mixed models are frequently applied to data with clustered categorical outcomes. The effect of clustering on the response is often difficult to practically assess partly because it is reported on a scale on which comparisons with regression parameters are difficult to make. This article proposes confidence intervals for…

  12. Likelihood-Based Confidence Intervals in Exploratory Factor Analysis

    ERIC Educational Resources Information Center

    Oort, Frans J.

    2011-01-01

    In exploratory or unrestricted factor analysis, all factor loadings are free to be estimated. In oblique solutions, the correlations between common factors are free to be estimated as well. The purpose of this article is to show how likelihood-based confidence intervals can be obtained for rotated factor loadings and factor correlations, by…

  13. Exercise-induced hypoalgesia - interval versus continuous mode.

    PubMed

    Kodesh, Einat; Weissman-Fogel, Irit

    2014-07-01

    Aerobic exercise at approximately 70% of maximal aerobic capacity moderately reduces pain sensitivity and attenuates pain, even after a single session. If the analgesic effects depend on exercise intensity, then high-intensity interval exercise at 85% of maximal aerobic capacity should further reduce pain. The aim of this study was to explore the exercise-induced analgesic effects of high-intensity interval aerobic exercise and to compare them with the analgesic effects of moderate continuous aerobic exercise. Twenty-nine young untrained healthy males were randomly assigned to aerobic-continuous (70% heart rate reserve (HRR)) and interval (4 × 4 min at 85% HRR and 2 min at 60% HRR between cycles) exercise modes, each lasting 30 min. Psychophysical pain tests, pressure and heat pain thresholds (HPT), and tonic heat pain (THP) were conducted before and after exercise sessions. Repeated measures ANOVA was used for data analysis. HPT increased (p = 0.056) and THP decreased (p = 0.013) following exercise unrelated to exercise type. However, the main time effect (pre-/postexercise) was a trend of increased HPT (45.6 ± 1.9 °C to 46.2 ± 1.8 °C; p = 0.082) and a significant reduction in THP (from 50.7 ± 25 to 45.9 ± 25.4 numeric pain scale; p = 0.043) following interval exercise. No significant change was found for the pressure pain threshold following either exercise type. In conclusion, interval exercise (85% HRR) has analgesic effects on experimental pain perception. This, in addition to its cardiovascular, muscular, and metabolic advantages may promote its inclusion in pain management programs. PMID:24773287

  14. The QT Interval and Risk of Incident Atrial Fibrillation

    PubMed Central

    Mandyam, Mala C.; Soliman, Elsayed Z.; Alonso, Alvaro; Dewland, Thomas A.; Heckbert, Susan R.; Vittinghoff, Eric; Cummings, Steven R.; Ellinor, Patrick T.; Chaitman, Bernard R.; Stocke, Karen; Applegate, William B.; Arking, Dan E.; Butler, Javed; Loehr, Laura R.; Magnani, Jared W.; Murphy, Rachel A.; Satterfield, Suzanne; Newman, Anne B.; Marcus, Gregory M.

    2013-01-01

    BACKGROUND Abnormal atrial repolarization is important in the development of atrial fibrillation (AF), but no direct measurement is available in clinical medicine. OBJECTIVE To determine whether the QT interval, a marker of ventricular repolarization, could be used to predict incident AF. METHODS We examined a prolonged QT corrected by the Framingham formula (QTFram) as a predictor of incident AF in the Atherosclerosis Risk in Communities (ARIC) study. The Cardiovascular Health Study (CHS) and Health, Aging, and Body Composition (Health ABC) study were used for validation. Secondary predictors included QT duration as a continuous variable, a short QT interval, and QT intervals corrected by other formulae. RESULTS Among 14,538 ARIC participants, a prolonged QTFram predicted a roughly two-fold increased risk of AF (hazard ratio [HR] 2.05, 95% confidence interval [CI] 1.42–2.96, p<0.001). No substantive attenuation was observed after adjustment for age, race, sex, study center, body mass index, hypertension, diabetes, coronary disease, and heart failure. The findings were validated in CHS and Health ABC and were similar across various QT correction methods. Also in ARIC, each 10-ms increase in QTFram was associated with an increased unadjusted (HR 1.14, 95%CI 1.10–1.17, p<0.001) and adjusted (HR 1.11, 95%CI 1.07–1.14, p<0.001) risk of AF. Findings regarding a short QT were inconsistent across cohorts. CONCLUSIONS A prolonged QT interval is associated with an increased risk of incident AF. PMID:23872693

  15. Modeling stream fish distributions using interval-censored detection times.

    PubMed

    Ferreira, Mário; Filipe, Ana Filipa; Bardos, David C; Magalhães, Maria Filomena; Beja, Pedro

    2016-08-01

    Controlling for imperfect detection is important for developing species distribution models (SDMs). Occupancy-detection models based on the time needed to detect a species can be used to address this problem, but this is hindered when times to detection are not known precisely. Here, we extend the time-to-detection model to deal with detections recorded in time intervals and illustrate the method using a case study on stream fish distribution modeling. We collected electrofishing samples of six fish species across a Mediterranean watershed in Northeast Portugal. Based on a Bayesian hierarchical framework, we modeled the probability of water presence in stream channels, and the probability of species occupancy conditional on water presence, in relation to environmental and spatial variables. We also modeled time-to-first detection conditional on occupancy in relation to local factors, using modified interval-censored exponential survival models. Posterior distributions of occupancy probabilities derived from the models were used to produce species distribution maps. Simulations indicated that the modified time-to-detection model provided unbiased parameter estimates despite interval-censoring. There was a tendency for spatial variation in detection rates to be primarily influenced by depth and, to a lesser extent, stream width. Species occupancies were consistently affected by stream order, elevation, and annual precipitation. Bayesian P-values and AUCs indicated that all models had adequate fit and high discrimination ability, respectively. Mapping of predicted occupancy probabilities showed widespread distribution by most species, but uncertainty was generally higher in tributaries and upper reaches. The interval-censored time-to-detection model provides a practical solution to model occupancy-detection when detections are recorded in time intervals. This modeling framework is useful for developing SDMs while controlling for variation in detection rates, as it

  16. Brain activity during interval timing depends on sensory structure.

    PubMed

    Pfeuty, Micha; Ragot, Richard; Pouthas, Viviane

    2008-04-14

    Precise timing is crucial for accurate perception and action in the range of hundreds of milliseconds. One still unresolved question concerns the influence of sensory information content on timing mechanisms. Numerous studies have converged to suggest that the CNV (Contingent Negative Variation), a slow negative wave that develops between two events, notably reflects temporal processing of the interval between these two events. The present study aimed at investigating CNV activity in duration discrimination tasks using either filled (continuous tones) or empty intervals (silent periods bounded by two brief tones). Participants had to compare a test duration with a 600-ms standard. Time perception was markedly better in the 'empty' than in the 'filled' condition. Electrophysiological analyses performed on the longest test duration (794 ms) of the comparison phase revealed an effect of the sensory structure on both the CNV amplitude and CNV time-course. The CNV amplitude was larger for filled than for empty intervals, suggesting a superimposition of timing-dependent activity and sensory sustained activity. Furthermore, the CNV time-course paralleled the temporal structure of the memorized sensory event: for filled intervals, the CNV amplitude stopped increasing at 600 ms, i.e. the expected end of the continuous tone; for empty intervals, in contrast, the CNV amplitude precisely increased at 600 ms, i.e. the expected onset of the second brief tone. These results suggest that the CNV reflects the mental rehearsal of the memorized sensory event, in line with the idea that temporal processing in the sub-second range is based on sensory information.

  17. QT Interval Variability Index and QT Interval Duration in Different Sleep Stages: Analysis of Polysomnographic Recordings in Nonapneic Male Patients

    PubMed Central

    Viigimae, Moonika; Karai, Deniss; Pirn, Peeter; Pilt, Kristjan; Meigas, Kalju; Kaik, Jyri

    2015-01-01

    The aim of the study was to determine whether different sleep stages, especially REM sleep, affect QT interval duration and variability in male patients without obstructive sleep apnea (OSA). Polysomnographic recordings of 30 patients were analyzed. Beat-to-beat QT interval variability was calculated using QTV index (QTVI) formula. For QTc interval calculation, in addition to Bazett's formula, linear and parabolic heart rate correction formulas with two separate α values were used. QTVI and QTc values were calculated as means of 2 awake, 3 NREM, and 3 REM sleep episodes; the duration of each episode was 300 sec. Mean QTVI values were not statistically different between sleep stages. Therefore, elevated QTVI values found in patients with OSA cannot be interpreted as physiological sympathetic impact during REM sleep and should be considered as a risk factor for potentially life-threatening ventricular arrhythmias. The absence of difference of the mean QTc interval values between NREM and REM stages seems to confirm our conclusion that sympathetic surges during REM stage do not induce repolarization variability. In patients without notable structural and electrical remodeling of myocardium, physiological elevation in sympathetic activity during REM sleep remains subthreshold concerning clinically significant increase of myocardial electrical instability. PMID:26693490

  18. QT Interval Variability Index and QT Interval Duration in Different Sleep Stages: Analysis of Polysomnographic Recordings in Nonapneic Male Patients.

    PubMed

    Viigimae, Moonika; Karai, Deniss; Pirn, Peeter; Pilt, Kristjan; Meigas, Kalju; Kaik, Jyri

    2015-01-01

    The aim of the study was to determine whether different sleep stages, especially REM sleep, affect QT interval duration and variability in male patients without obstructive sleep apnea (OSA). Polysomnographic recordings of 30 patients were analyzed. Beat-to-beat QT interval variability was calculated using QTV index (QTVI) formula. For QTc interval calculation, in addition to Bazett's formula, linear and parabolic heart rate correction formulas with two separate α values were used. QTVI and QTc values were calculated as means of 2 awake, 3 NREM, and 3 REM sleep episodes; the duration of each episode was 300 sec. Mean QTVI values were not statistically different between sleep stages. Therefore, elevated QTVI values found in patients with OSA cannot be interpreted as physiological sympathetic impact during REM sleep and should be considered as a risk factor for potentially life-threatening ventricular arrhythmias. The absence of difference of the mean QTc interval values between NREM and REM stages seems to confirm our conclusion that sympathetic surges during REM stage do not induce repolarization variability. In patients without notable structural and electrical remodeling of myocardium, physiological elevation in sympathetic activity during REM sleep remains subthreshold concerning clinically significant increase of myocardial electrical instability. PMID:26693490

  19. Relationship between the Initial Systolic Time Interval and RR-interval during an exercise stimulus measured with Impedance Cardiography

    NASA Astrophysics Data System (ADS)

    Hoekstra, Femke; Habers, Esther; Janssen, Thomas W. J.; Verdaasdonk, Rudolf M.; Meijer, Jan H.

    2010-04-01

    The Initial Systolic Time Interval (ISTI), obtained from the electrocardiogram and impedance cardiogram, is considered to be a measure for the time delay between the electrical and mechanical activity of the heart and reflects an active period of the heart cycle. The relationship between ISTI and the total heart cycle (RR-interval) was studied in three groups of young, healthy volunteers: low, moderately and highly trained subjects. The three groups were exposed to an exercise stimulus on a cycle ergometer with an increasing work load to increase the heart rate. ISTI was decreased with decreasing RR-interval. However, the relative proportion of ISTI, ISTI/RR, was found to increase with decreasing RR-interval. This relationship was found to be inversely proportional. The rate of this increase in ISTI/RR was significantly higher in highly trained subjects. Also, over the whole range of heart rates ISTI was longer in these subjects. It is concluded that ISTI can be used to evaluate cardiac performance during physical exercise non-invasively and in an extramural setting.

  20. Altering the rest interval during high-intensity interval training does not affect muscle or performance adaptations.

    PubMed

    Edge, Johann; Eynon, Nir; McKenna, Michael J; Goodman, Craig A; Harris, Roger C; Bishop, David J

    2013-02-01

    It has been hypothesized that exercise-induced changes in metabolites and ions are crucial in the adaptation of contracting muscle. We tested this hypothesis by comparing adaptations to two different interval-training protocols (differing only in the rest duration between intervals), which provoked different perturbations in muscle metabolites and acid-base status. Prior to and immediately after training, 12 women performed the following tests: (1) a graded exercise test to determine peak oxygen uptake (V(O2)); (2) a high-intensity exercise bout (followed 60 s later by a repeated-sprint-ability test; and (3) a repeat of the high-intensity exercise bout alone with muscle biopsies pre-exercise, immediately postexercise and after 60 s of recovery. Subjects performed 5 weeks (3 days per week) of training, with either a short (1 min; HIT-1) or a long rest period (3 min; HIT-3) between intervals; training intensity and volume were matched. Muscle [H(+)] (155 ± 15 versus 125 ± 8 nmol l(-1); P < 0.05) and muscle lactate content (84.2 ± 7.9 versus 46.9 ± 3.1 mmol (g wet weight)(-1)) were both higher after HIT-1, while muscle phosphocreatine (PCr) content (52.8 ± 8.3 versus 63.4 ± 9.8 mmol (g wet weight)(-1)) was lower. There were no significant differences between the two groups regarding the increases in , repeated-sprint performance or muscle Na(+),K(+)-ATPase content. Following training, both groups had a significant decrease in postexercise muscle [H(+)] and lactate content, but not postexercise ATP or PCr. Postexercise PCr resynthesis increased following both training methods. In conclusion, intense interval training results in marked improvements in muscle Na(+),K(+)-ATPase content, PCr resynthesis and . However, manipulation of the rest period during intense interval training did not affect these changes.

  1. High-Intensity Interval Training with Vibration as Rest Intervals Attenuates Fiber Atrophy and Prevents Decreases in Anaerobic Performance

    PubMed Central

    Mueller, Sandro Manuel; Aguayo, David; Zuercher, Matthias; Fleischmann, Oliver; Boutellier, Urs; Auer, Maria; Jung, Hans H.; Toigo, Marco

    2015-01-01

    Aerobic high-intensity interval training (HIT) improves cardiovascular capacity but may reduce the finite work capacity above critical power (W′) and lead to atrophy of myosin heavy chain (MyHC)-2 fibers. Since whole-body vibration may enhance indices of anaerobic performance, we examined whether side-alternating whole-body vibration as a replacement for the active rest intervals during a 4x4 min HIT prevents decreases in anaerobic performance and capacity without compromising gains in aerobic function. Thirty-three young recreationally active men were randomly assigned to conduct either conventional 4x4 min HIT, HIT with 3 min of WBV at 18 Hz (HIT+VIB18) or 30 Hz (HIT+VIB30) in lieu of conventional rest intervals, or WBV at 30 Hz (VIB30). Pre and post training, critical power (CP), W′, cellular muscle characteristics, as well as cardiovascular and neuromuscular variables were determined. W′ (−14.3%, P = 0.013), maximal voluntary torque (−8.6%, P = 0.001), rate of force development (−10.5%, P = 0.018), maximal jumping power (−6.3%, P = 0.007) and cross-sectional areas of MyHC-2A fibers (−6.4%, P = 0.044) were reduced only after conventional HIT. CP, V̇O2peak, peak cardiac output, and overall capillary-to-fiber ratio were increased after HIT, HIT+VIB18, and HIT+VIB30 without differences between groups. HIT-specific reductions in anaerobic performance and capacity were prevented by replacing active rest intervals with side-alternating whole-body vibration, notably without compromising aerobic adaptations. Therefore, competitive cyclists (and potentially other endurance-oriented athletes) may benefit from replacing the active rest intervals during aerobic HIT with side-alternating whole-body vibration. Trial Registration ClinicalTrials.gov Identifier: NCT01875146 PMID:25679998

  2. Effect of clozapine on interval timing and working memory for time in the peak-interval procedure with gaps.

    PubMed

    Buhusi, Catalin V; Meck, Warren H

    2007-02-22

    Previous research indicates that dopamine controls both the speed of an internal clock [Maricq, A.V., Church, R.M., 1983. The differential effects of haloperidol and methamphetamine on time estimation in the rat. Psychopharmacology 79, 10-15] and sharing of resources between the timer and other cognitive processes [Buhusi, C.V., 2003. Dopaminergic mechanisms of interval timing and attention. In: Meck, W.H. (Ed.), Functional and Neural Mechanisms of Interval Timing. CRC Press, Boca Raton, FL, pp. 317-338]. For example, dopamine agonist methamphetamine increases the speed of an internal clock and resets timing after a gap, while dopamine antagonist haloperidol decreases the speed of an internal clock and stops timing during a gap [Buhusi, C.V., Meck, W.H., 2002. Differential effects of methamphetamine and haloperidol on the control of an internal clock. Behav. Neurosci. 116, 291-297]. Using a 20-s peak-interval procedure with gaps we examined the acute effects of clozapine (2.0mg/kg i.p.), which exerts differential effects on dopamine and serotonin in the cortex and striatum, two brain areas involved in interval timing and working memory. Relative to saline, clozapine injections shifted the response functions leftward both in trials with and without gaps, suggesting that clozapine increased the speed of an internal clock and facilitated the maintenance of the pre-gap interval in working memory. These results suggest that clozapine exerts effects in different brain areas in a manner that allows for the pharmacological separation of clock speed and working memory as a function of peak trials without and with gaps.

  3. Wind Information Uplink to Aircraft Performing Interval Management Operations

    NASA Technical Reports Server (NTRS)

    Ahmad, Nashat; Barmore, Bryan; Swieringa, Kurt

    2015-01-01

    The accuracy of the wind information used to generate trajectories for aircraft performing Interval Management (IM) operations is critical to the success of an IM operation. There are two main forms of uncertainty in the wind information used by the Flight Deck Interval Management (FIM) equipment. The first is the accuracy of the forecast modeling done by the weather provider. The second is that only a small subset of the forecast data can be uplinked to the aircraft for use by the FIM equipment, resulting in loss of additional information. This study focuses on what subset of forecast data, such as the number and location of the points where the wind is sampled should be made available to uplink to the aircraft.

  4. Matching and maximizing with concurrent ratio-interval schedules.

    PubMed

    Green, L; Rachlin, H; Hanson, J

    1983-11-01

    Animals exposed to standard concurrent variable-ratio variable-interval schedules could maximize overall reinforcement rate if, in responding, they showed a strong response bias toward the variable-ratio schedule. Tests with the standard schedules have failed to find such a bias and have been widely cited as evidence against maximization as an explanation of animal choice behavior. However, those experiments were confounded in that the value of leisure (behavior other than the instrumental response) partially offsets the value of reinforcement. The present experiment provides another such test using a concurrent procedure in which the confounding effects of leisure were mostly eliminated while the critical aspects of the concurrent variable-ratio variable-interval contingency were maintained: Responding in one component advanced only its ratio schedule while responding in the other component advanced both ratio schedules. The bias toward the latter component predicted by maximization theory was found.

  5. Reinforcer concentration effects on a fixed-interval schedule.

    PubMed

    Blomeley, Frances J; Lowe, C F; Wearden, J H

    2004-07-30

    Four rats received training on a mixed FI 30-s FI 150-s schedule, where the different FI values were associated with different levers. During baseline, the reinforcer was a 30% concentration of condensed milk. During subsequent testing sessions, the reinforcer concentration was varied within sessions over values of 10, 30, 50, and 70%. Measures of behaviour were taken from the FI 30-s lever during trials where the reinforcer was delivered for responses on the other lever. Increasing the reinforcer concentration which began the interval (a) increased the time to start responding in the interval, and (b) increased the location of the response peak on the FI 30-s lever (often to values well above 30s). Response rate at the peak, and spread of the response rate versus time function, changed much less with reinforcer concentration. The data are discussed relative to predictions derived from Scalar Expectancy Theory, the Behavioural Theory of Timing, and the Tuned-trace model.

  6. Momentary maximizing in concurrent schedules with a minimum interchangeover interval.

    PubMed

    Todorov, J C; Souza, D G; Bori, C M

    1993-09-01

    Eight pigeons were trained on concurrent variable-interval variable-interval schedules with a minimum interchangeover time programmed as a consequence of changeovers. In Experiment 1 the reinforcement schedules remained constant while the minimum interchangeover time varied from 0 to 200 s. Relative response rates and relative time deviated from relative reinforcement rates toward indifference with long minimum interchangeover times. In Experiment 2 different reinforcement ratios were scheduled in successive experimental conditions with the minimum interchangeover time constant at 0, 2, 10, or 120 s. The exponent of the generalized matching equation was close to 1.0 when the minimum interchangeover time was 0 s (the typical procedure for concurrent schedules without a changeover delay) and decreased as that duration was increased. The data support the momentary maximizing theory and contradict molar maximizing theories and the melioration theory.

  7. Review of High-intensity Interval Training in Cardiac Rehabilitation.

    PubMed

    Ito, Shigenori; Mizoguchi, Tatsuya; Saeki, Tomoaki

    2016-01-01

    For the secondary prevention of cardiovascular disease, comprehensive cardiac rehabilitation is required. This involves optimal medical therapy, education on nutrition and exercise therapy, and smoking cessation. Of these, efficient exercise therapy is a key factor. A highly effective training protocol is therefore warranted, which requires a high rate of compliance. Although moderate-intensity continuous training has been the main training regimen recommended in cardiac rehabilitation guidelines, high-intensity interval training has been reported to be more effective in the clinical and experimental setting from the standpoint of peak oxygen uptake and central and peripheral adaptations. In this review, we illustrate the scientific evidence for high-intensity interval training. We then verify this evidence and discuss its significance and the remaining issues. PMID:27580530

  8. A nonparametric approach to extract information from interspike interval data.

    PubMed

    Rossoni, Enrico; Feng, Jianfeng

    2006-01-15

    In this work we develop an approach to extracting information from neural spike trains. Using the expectation-maximization (EM) algorithm, interspike interval data from experiments and simulations are fitted by mixtures of distributions, including Gamma, inverse Gaussian, log-normal, and the distribution of the interspike intervals of the leaky integrate-and-fire model. In terms of the Kolmogorov-Smirnov test for goodness-of-fit, our approach is proved successful (P>0.05) in fitting benchmark data for which a classical parametric approach has been shown to fail before. In addition, we present a novel method to fit mixture models to censored data, and discuss two examples of the application of such a method, which correspond to the case of multiple-trial and multielectrode array data. A MATLAB implementation of the algorithm is available for download from .

  9. Review of High-intensity Interval Training in Cardiac Rehabilitation.

    PubMed

    Ito, Shigenori; Mizoguchi, Tatsuya; Saeki, Tomoaki

    2016-01-01

    For the secondary prevention of cardiovascular disease, comprehensive cardiac rehabilitation is required. This involves optimal medical therapy, education on nutrition and exercise therapy, and smoking cessation. Of these, efficient exercise therapy is a key factor. A highly effective training protocol is therefore warranted, which requires a high rate of compliance. Although moderate-intensity continuous training has been the main training regimen recommended in cardiac rehabilitation guidelines, high-intensity interval training has been reported to be more effective in the clinical and experimental setting from the standpoint of peak oxygen uptake and central and peripheral adaptations. In this review, we illustrate the scientific evidence for high-intensity interval training. We then verify this evidence and discuss its significance and the remaining issues.

  10. Realtime Multichannel System for Beat to Beat QT Interval Variability

    NASA Technical Reports Server (NTRS)

    Starc, Vito; Schlegel, Todd T.

    2006-01-01

    The measurement of beat-to-beat QT interval variability (QTV) shows clinical promise for identifying several types of cardiac pathology. However, until now, there has been no device capable of displaying, in real time on a beattobeat basis, changes in QTV in all 12 conventional leads in a continuously monitored patient. While several software programs have been designed to analyze QTV, heretofore, such programs have all involved only a few channels (at most) and/or have required laborious user interaction or offline calculations and postprocessing, limiting their clinical utility. This paper describes a PC-based ECG software program that in real time, acquires, analyzes and displays QTV and also PQ interval variability (PQV) in each of the eight independent channels that constitute the 12lead conventional ECG. The system also processes certain related signals that are derived from singular value decomposition and that help to reduce the overall effects of noise on the realtime QTV and PQV results.

  11. Confidence intervals in Flow Forecasting by using artificial neural networks

    NASA Astrophysics Data System (ADS)

    Panagoulia, Dionysia; Tsekouras, George

    2014-05-01

    One of the major inadequacies in implementation of Artificial Neural Networks (ANNs) for flow forecasting is the development of confidence intervals, because the relevant estimation cannot be implemented directly, contrasted to the classical forecasting methods. The variation in the ANN output is a measure of uncertainty in the model predictions based on the training data set. Different methods for uncertainty analysis, such as bootstrap, Bayesian, Monte Carlo, have already proposed for hydrologic and geophysical models, while methods for confidence intervals, such as error output, re-sampling, multi-linear regression adapted to ANN have been used for power load forecasting [1-2]. The aim of this paper is to present the re-sampling method for ANN prediction models and to develop this for flow forecasting of the next day. The re-sampling method is based on the ascending sorting of the errors between real and predicted values for all input vectors. The cumulative sample distribution function of the prediction errors is calculated and the confidence intervals are estimated by keeping the intermediate value, rejecting the extreme values according to the desired confidence levels, and holding the intervals symmetrical in probability. For application of the confidence intervals issue, input vectors are used from the Mesochora catchment in western-central Greece. The ANN's training algorithm is the stochastic training back-propagation process with decreasing functions of learning rate and momentum term, for which an optimization process is conducted regarding the crucial parameters values, such as the number of neurons, the kind of activation functions, the initial values and time parameters of learning rate and momentum term etc. Input variables are historical data of previous days, such as flows, nonlinearly weather related temperatures and nonlinearly weather related rainfalls based on correlation analysis between the under prediction flow and each implicit input

  12. Interval estimation for uncertain systems with time-varying delays

    NASA Astrophysics Data System (ADS)

    Efimov, Denis; Perruquetti, Wilfrid; Richard, Jean-Pierre

    2013-10-01

    The estimation problem for uncertain time-delay systems is addressed. A design method of reduced-order interval observers is proposed. The observer estimates the set of admissible values (the interval) for the state at each instant of time. The cases of known fixed delays and uncertain time-varying delays are analysed. The proposed approach can be applied to linear delay systems and nonlinear time-delay systems in the output canonical form. It involves the properties of quasi-monotone/Metzler/cooperative systems. In this framework, it is shown that if under a suitable coordinate transformation the delay-free subsystem is cooperative, then the delayed estimation error dynamics inherits this property. The conditions to find the observer gains are formulated in the form of LMI. The framework efficiency is demonstrated on examples of nonlinear systems.

  13. Single-file diffusion in an interval: first passage properties.

    PubMed

    Ryabov, Artem

    2013-04-21

    We investigate the long-time behavior of the survival probability of a tagged particle in a single-file diffusion in a finite interval. The boundary conditions are of two types: (1) one boundary is absorbing the second is reflecting and (2) both boundaries are absorbing. For each type of the boundary conditions we consider two types of initial conditions: (a) initial number of particles N is given and (b) initial concentration of particles is given (N is random). In all four cases the tagged-particle survival probability exhibits different asymptotic behavior. When the both boundaries are absorbing we also consider a case of a random interval length (single-file diffusion on a line with randomly distributed traps). In the latter setting, the initial concentration of particles has the same effect on the asymptotic decay of the survival probability as the concentration of traps.

  14. Determination of post-burial interval using entomology: A review.

    PubMed

    Singh, Rajinder; Sharma, Sahil; Sharma, Arun

    2016-08-01

    Insects and other arthropods are used in different matters pertinent to the criminal justice system as they play very important role in the decomposition of cadavers. They are used as evidence in a criminal investigation to determine post mortem interval (PMI). Various researches and review articles are available on forensic entomology to determine PMI in the terrestrial environment but very less work has been reported in context to buried bodies. Burring the carcass, is one of the methods used by criminals to conceal the crime. So, to drive the attention of researchers toward this growing field and to help various investigating agencies, the present paper reviews the studies done on determination of post-burial interval (PBI), its importance and future prospective. PMID:27235895

  15. Prolonged QT interval in a man with anorexia nervosa

    PubMed Central

    Macías-Robles, María Dolores; Perez-Clemente, Ana María; Maciá-Bobes, Carmen; Alvarez-Rueda, María Asunción; Pozo-Nuevo, Sergio

    2009-01-01

    Anorexia nervosa is an eating disorder characterized by the avoidance of food intake, which usually leads to a weight loss. Cardiac co-morbility is common and we can find sometimes a mass loss from the left ventricle, which can be seen by echocardiography. But the commonest complications are rhythm variations, typically bradycardia with a prolonged QT interval in up to a 40% of the cases, which altogether elevates ventricular tachycardia and sudden death risk. We present the case of a male who was diagnosed with anorexia nervosa and developed asthenia, a long QT interval and also a severe both hypokalaemia and hypomagnesaemia. We intend to discuss the pathogenic paths as well as prophylactic and therapeutic measures to this potentially-lethal pathology. PMID:19646241

  16. A multivariate rate equation for variable-interval performance.

    PubMed

    McDowell, J J; Kessel, R

    1979-03-01

    A value-like parameter is introduced into a rate equation for describing variable-interval performance. The equation, derived solely from formal considerations, expresses rate of responding as a joint function of rate of reinforcement and "reinforcer power." Preliminary tests of the rate equation show that it handles univariate data as well as Herrnstein's hyperbola. In addition, a form of Herrnstein's hyperbola can be derived from the equation, and it predicts forms of matching in concurrent situations. For the multivariate case, reinforcer values scaled in concurrent situations where matching is assumed to hold are taken as determinations of reinforcer power. The multivariate rate equation is fitted to an appropriate set of data and found to provide a good description of variable-interval performance when both rate and power of reinforcement are varied. Rate and power measures completely describe reinforcement. The effects of their joint variation are not predicted and cannot be described by Herrnstein's equation.

  17. Computing connection coefficients of compactly supported wavelets on bounded intervals

    SciTech Connect

    Romine, C.H.; Peyton, B.W.

    1997-04-01

    Daubechies wavelet basis functions have many properties that make them desirable as a basis for a Galerkin approach to solving PDEs: they are orthogonal, with compact support, and their connection coefficients can be computed. The method developed by Latto et al. to compute connection coefficients does not provide the correct inner product near the endpoints of a bounded interval, making the implementation of boundary conditions problematic. Moreover, the highly oscillatory nature of the wavelet basis functions makes standard numerical quadrature of integrals near the boundary impractical. The authors extend the method of Latto et al. to construct and solve a linear system of equations whose solution provides the exact computation of the integrals at the boundaries. As a consequence, they provide the correct inner product for wavelet basis functions on a bounded interval.

  18. Computation of robustly stabilizing PID controllers for interval systems.

    PubMed

    Matušů, Radek; Prokop, Roman

    2016-01-01

    The paper is focused on the computation of all possible robustly stabilizing Proportional-Integral-Derivative (PID) controllers for plants with interval uncertainty. The main idea of the proposed method is based on Tan's (et al.) technique for calculation of (nominally) stabilizing PI and PID controllers or robustly stabilizing PI controllers by means of plotting the stability boundary locus in either P-I plane or P-I-D space. Refinement of the existing method by consideration of 16 segment plants instead of 16 Kharitonov plants provides an elegant and efficient tool for finding all robustly stabilizing PID controllers for an interval system. The validity and relatively effortless application of presented theoretical concepts are demonstrated through a computation and simulation example in which the uncertain mathematical model of an experimental oblique wing aircraft is robustly stabilized. PMID:27350931

  19. Systolic time intervals after a seven-day orbital flight

    NASA Astrophysics Data System (ADS)

    Groza, P.; Vrâncianu, R.; Lazǎr, M.; Baevski, R. M.; Funtova, V. L.

    Heart rate, systolic time intervals (pre-ejection period, left ventricular ejection time), ejection fraction, stroke volume and QT interval of two cosmonauts (Leonid Popov - L.P. and Dumitru Prunariu - D.P.) were studied before, during, and after an ergometric bicycle exercise test performed before and after the seven-day Soviet-Romanian orbital flight on the Soyuz 40 - Salyut 6 Complex in May 1981. For this purpose one precordial electrocardiogram (ecg) and the ear photodensitogram (den) were recorded stimulaneously. The method used permitted recording even during exercise, Ecg and den signals were stored on magnetic tape, processed in an analogue device and in a digital computer. The data obtained after landing suggest a slight cardiac deconditioning in L.P., demonstrated especially by augmentation of the pre-ejection period, which was unchanged in D.P. corresponding to a sympathoadrenergic hypertonia. The seven-day orbital flight has not produced important cardiovascular changes.

  20. [Recent advancement in relationship between DNA degradation and postmortem interval].

    PubMed

    Hao, Lu-gui; Deng, Shi-Xiong; Zhao, Xin-Cai

    2007-04-01

    Determination of postmortem interval (PMI) is one of the most valuable subjects in forensic practice. It, however, is often very difficult to accurately determine the PMI in daily practice. Forensic DNA technology has recently been used to estimate the PMI. It has certain advantage to traditional methods. This article reviews this technology with respect to its invention, development, advantage, disadvantage, and potential future applications with emphasis on correlation of DNA degradation and PMI. PMID:17619465

  1. Audiovisual Interval Size Estimation Is Associated with Early Musical Training

    PubMed Central

    Abel, Mary Kathryn; Li, H. Charles; Russo, Frank A.; Schlaug, Gottfried; Loui, Psyche

    2016-01-01

    Although pitch is a fundamental attribute of auditory perception, substantial individual differences exist in our ability to perceive differences in pitch. Little is known about how these individual differences in the auditory modality might affect crossmodal processes such as audiovisual perception. In this study, we asked whether individual differences in pitch perception might affect audiovisual perception, as it relates to age of onset and number of years of musical training. Fifty-seven subjects made subjective ratings of interval size when given point-light displays of audio, visual, and audiovisual stimuli of sung intervals. Audiovisual stimuli were divided into congruent and incongruent (audiovisual-mismatched) stimuli. Participants’ ratings correlated strongly with interval size in audio-only, visual-only, and audiovisual-congruent conditions. In the audiovisual-incongruent condition, ratings correlated more with audio than with visual stimuli, particularly for subjects who had better pitch perception abilities and higher nonverbal IQ scores. To further investigate the effects of age of onset and length of musical training, subjects were divided into musically trained and untrained groups. Results showed that among subjects with musical training, the degree to which participants’ ratings correlated with auditory interval size during incongruent audiovisual perception was correlated with both nonverbal IQ and age of onset of musical training. After partialing out nonverbal IQ, pitch discrimination thresholds were no longer associated with incongruent audio scores, whereas age of onset of musical training remained associated with incongruent audio scores. These findings invite future research on the developmental effects of musical training, particularly those relating to the process of audiovisual perception. PMID:27760134

  2. Opinion Paper: Deriving Harmonised Reference Intervals – Global Activities

    PubMed Central

    Koerbin, Gus; Adeli, Khosrow

    2016-01-01

    Harmonisation of reference intervals (RIs) refers to use of the same or common RI across different platforms and /or assays for a specified analyte. It occurs optimally for those analytes where there is sound calibration and traceability in place and evidence from a between-method comparison shows that bias would not prevent the use of a common RI. The selection of the RI will depend on various sources of information including local formal RI studies, published studies from the literature, laboratory surveys, manufacturer’s product information, relevant guidelines, and mining of databases. Pre-analytical and partitioning issues, significant figures and flagging rates, are assessed for each analyte. Several countries and regions including the Nordic countries, United Kingdom, Japan, Turkey, and Australasia are using common RIs that have been determined either by direct studies or by a consensus process. In Canada, the Canadian Society of Clinical Chemists Taskforce is assessing the feasibility of establishing common reference values using the CALIPER (Canadian Laboratory Initiative on Pediatric Reference Intervals) and CHMS (The Canadian Health Measures Survey) databases as the basis. Development of platform-specific common reference values for each of the major analytical systems may be a more practical approach especially for the majority of analytes that are not standardised against a primary reference method and are not traceable to a primary or secondary reference material. We encourage laboratories to consider adopting reference intervals consistent with those used by other laboratories in your region where it is possible and appropriate for your local population. Local validation of the adopted reference interval is also recommended as per CLSI guidelines. PMID:27683506

  3. Opinion Paper: Deriving Harmonised Reference Intervals - Global Activities.

    PubMed

    Tate, Jillian R; Koerbin, Gus; Adeli, Khosrow

    2016-02-01

    Harmonisation of reference intervals (RIs) refers to use of the same or common RI across different platforms and /or assays for a specified analyte. It occurs optimally for those analytes where there is sound calibration and traceability in place and evidence from a between-method comparison shows that bias would not prevent the use of a common RI. The selection of the RI will depend on various sources of information including local formal RI studies, published studies from the literature, laboratory surveys, manufacturer's product information, relevant guidelines, and mining of databases. Pre-analytical and partitioning issues, significant figures and flagging rates, are assessed for each analyte. Several countries and regions including the Nordic countries, United Kingdom, Japan, Turkey, and Australasia are using common RIs that have been determined either by direct studies or by a consensus process. In Canada, the Canadian Society of Clinical Chemists Taskforce is assessing the feasibility of establishing common reference values using the CALIPER (Canadian Laboratory Initiative on Pediatric Reference Intervals) and CHMS (The Canadian Health Measures Survey) databases as the basis. Development of platform-specific common reference values for each of the major analytical systems may be a more practical approach especially for the majority of analytes that are not standardised against a primary reference method and are not traceable to a primary or secondary reference material. We encourage laboratories to consider adopting reference intervals consistent with those used by other laboratories in your region where it is possible and appropriate for your local population. Local validation of the adopted reference interval is also recommended as per CLSI guidelines. PMID:27683506

  4. Versatile all-digital time interval measuring system

    NASA Astrophysics Data System (ADS)

    Vyhlidal, David; Cech, Miroslav

    2011-06-01

    This paper describes a design and performance of a versatile all-digital time interval measuring system. The measurement method is based on an interpolation principle. In this principle the time interval is first roughly digitized by a coarse counter driven by a high stability reference clock and the fractions between the clock periods are measured by two Time-to-Digital Converter chips TDC-GPX manufactured by Acam messelectronic. Control circuits allow programmable customization of the system to satisfy many applications such as laser range finding, event counting, or time-of-flight measurements in various physics experiments. The system has two reference clocks inputs and two independent channels for measuring start and stop events. Only one 40 MHz reference is required for the measurement. The second reference can be, for example, 1 PPS (Pulse per Second) signal from a GPS (Global Positioning System) to time tag events. Time intervals are measured using the highest resolution mode of the TDC-GPX chips. The resolution of each chip is software programmable and is PLL (Phase Locked Loop) stabilized against temperature and voltage variations. The system can achieve a timing resolution better than 15 ps rms with up to 90 kHz repetition rate. The time interval measurement range is from 0 ps up to 1 second. The power consumption of the whole system is 18 W including an embedded computer board and an LCD (Liquid Crystal Display) screen. The embedded computer controls the whole system, collects and evaluates measurement data and with the display provides a user interface. The system is implemented using commercially available components.

  5. Race-specific WBC and neutrophil count reference intervals.

    PubMed

    Lim, E-M; Cembrowski, George; Cembrowski, M; Clarke, G

    2010-12-01

    Healthy African Americans are known to have reduced white blood cell counts (WBC) and absolute neutrophil counts (ANC) compared with European Americans, with little agreement about the levels in reference intervals. The objective is to establish race-specific reference intervals for WBC and ANC using US National Health and Nutrition Examination Survey (NHANES) of 2000-2003. A total of 14,184 civilian noninstitutionalized US citizens participated in NHANES 2000-2003 had complete blood count, red cell distribution width, platelet count and automated WBC differential determined on a Coulter MAXM. The exclusion criteria were used: ferritin <12 ng/ml, pregnancy, body mass index >30, diastolic blood pressure >100 mm Hg, creatinine >2.5 mg/dl, glucose >126 mg/dl. Data were separated into six sex/race categories: female non-Hispanic white, non-Hispanic black (NHBF)], Mexican American; male non-Hispanic white, non-Hispanic black (NHBM), Mexican American and two age groupings (12-18 and >18 years). NHB 2.5-97.5 percentile WBC and (ANC) limits follow (units: × 10⁹ /l): NHBM, ages 12-18: 3.2-9.3 (1.0-6.2); NHBF, ages 12-18: 3.7-10.1 (1.2-6.6); adult NHBM: 3.1-9.9 (1.3-6.6); adult NHBF: 3.4-11 (1.4-7.5). NHB limits are significantly lower than the NHW and MA limits. In most US healthcare organizations, insufficient agreement exists because of large differences in reference intervals for different ethnicities. In areas with peoples of African descent (>10--20%), race-specific WBC and ANC reference intervals must be provided for proper diagnosis and clinical research.

  6. Stability Problem of Canard-Cycles on a Finite Interval

    NASA Astrophysics Data System (ADS)

    Chumakov, Gennadii A.; Chumakova, Nataliya A.; Lashina, Elena A.

    2010-09-01

    A detailed study of two-variable mathematical model of a heterogeneous catalytic reaction is presented with special attention to the stability problem of canard-cycles on a finite interval. Our analysis of the global error behavior in a long-time numerical integration shows that a high sensitive dependence on the initial conditions appears due to the existence of a shower-type bundle of trajectories which is formed by stable and unstable canard solutions.

  7. Multifactor analysis of multiscaling in volatility return intervals

    NASA Astrophysics Data System (ADS)

    Wang, Fengzhong; Yamasaki, Kazuko; Havlin, Shlomo; Stanley, H. Eugene

    2009-01-01

    We study the volatility time series of 1137 most traded stocks in the U.S. stock markets for the two-year period 2001-2002 and analyze their return intervals τ , which are time intervals between volatilities above a given threshold q . We explore the probability density function of τ , Pq(τ) , assuming a stretched exponential function, Pq(τ)˜e-τγ . We find that the exponent γ depends on the threshold in the range between q=1 and 6 standard deviations of the volatility. This finding supports the multiscaling nature of the return interval distribution. To better understand the multiscaling origin, we study how γ depends on four essential factors, capitalization, risk, number of trades, and return. We show that γ depends on the capitalization, risk, and return but almost does not depend on the number of trades. This suggests that γ relates to the portfolio selection but not on the market activity. To further characterize the multiscaling of individual stocks, we fit the moments of τ , μm≡⟨(τ/⟨τ⟩)m⟩1/m , in the range of 10<⟨τ⟩⩽100 by a power law, μm˜⟨τ⟩δ . The exponent δ is found also to depend on the capitalization, risk, and return but not on the number of trades, and its tendency is opposite to that of γ . Moreover, we show that δ decreases with increasing γ approximately by a linear relation. The return intervals demonstrate the temporal structure of volatilities and our findings suggest that their multiscaling features may be helpful for portfolio optimization.

  8. Influence of the dosing interval on prolactin release after remoxipride.

    PubMed Central

    Movin-Osswald, G; Hammarlund-Udenaes, M; Von Bahr, C; Eneroth, P; Walton-Bowen, K

    1995-01-01

    1. The prolactin response following administration of the D2-dopamine receptor antagonist remoxipride was studied in eight healthy male volunteers. The purpose of the study was to investigate the duration of a refractory period of prolactin release following two doses of remoxipride. A further aim was to compare the prolactin response following remoxipride and thyrotropin release hormone (TRH) during the refractory period. The subjects received two 30 min intravenous (i.v.) infusions of remoxipride 50 mg with different time intervals between the two doses, in a randomized six period crossover design. The time intervals between the two remoxipride doses were 2, 8, 12, 24 and 48 h. On one occasion the remoxipride dose was followed by an i.v. injection of TRH after 2 h. 2. The plasma peak prolactin concentrations obtained after the first remoxipride dose correspond to a maximal release of prolactin according to earlier studies. A small second peak of prolactin was observed after 2 h. The release was gradually increased with longer time intervals between the consecutive doses. The refractory period for a second prolactin release similar to the first one after remoxipride was found to be 24 h for most of the subjects. 3. TRH resulted in a faster and higher increase in prolactin response of a shorter duration than after remoxipride administered 2 h after the first dose. PMID:7669486

  9. Perception of acoustically presented time series with varied intervals.

    PubMed

    Wackermann, Jiří; Pacer, Jakob; Wittmann, Marc

    2014-03-01

    Data from three experiments on serial perception of temporal intervals in the supra-second domain are reported. Sequences of short acoustic signals ("pips") separated by periods of silence were presented to the observers. Two types of time series, geometric or alternating, were used, where the modulus 1+δ of the inter-pip series and the base duration Tb (range from 1.1 to 6s) were varied as independent parameters. The observers had to judge whether the series were accelerating, decelerating, or uniform (3 paradigm), or to distinguish regular from irregular sequences (2 paradigm). "Intervals of subjective uniformity" (isus) were obtained by fitting Gaussian psychometric functions to individual subjects' responses. Progression towards longer base durations (Tb=4.4 or 6s) shifts the isus towards negative δs, i.e., accelerating series. This finding is compatible with the phenomenon of "subjective shortening" of past temporal intervals, which is naturally accounted for by the lossy integration model of internal time representation. The opposite effect observed for short durations (Tb=1.1 or 1.5s) remains unexplained by the lossy integration model, and presents a challenge for further research.

  10. Robust inter-beat interval estimation in cardiac vibration signals.

    PubMed

    Brüser, C; Winter, S; Leonhardt, S

    2013-02-01

    Reliable and accurate estimation of instantaneous frequencies of physiological rhythms, such as heart rate, is critical for many healthcare applications. Robust estimation is especially challenging when novel unobtrusive sensors are used for continuous health monitoring in uncontrolled environments, because these sensors can create significant amounts of potentially unreliable data. We propose a new flexible algorithm for the robust estimation of local (beat-to-beat) intervals from cardiac vibration signals, specifically ballistocardiograms (BCGs), recorded by an unobtrusive bed-mounted sensor. This sensor allows the measurement of motions of the body which are caused by cardiac activity. Our method requires neither a training phase nor any prior knowledge about the morphology of the heart beats in the analyzed waveforms. Instead, three short-time estimators are combined using a Bayesian approach to continuously estimate the inter-beat intervals. We have validated our method on over-night BCG recordings from 33 subjects (8 normal, 25 insomniacs). On this dataset, containing approximately one million heart beats, our method achieved a mean beat-to-beat interval error of 0.78% with a coverage of 72.69%.

  11. An uncertain multidisciplinary design optimization method using interval convex models

    NASA Astrophysics Data System (ADS)

    Li, Fangyi; Luo, Zhen; Sun, Guangyong; Zhang, Nong

    2013-06-01

    This article proposes an uncertain multi-objective multidisciplinary design optimization methodology, which employs the interval model to represent the uncertainties of uncertain-but-bounded parameters. The interval number programming method is applied to transform each uncertain objective function into two deterministic objective functions, and a satisfaction degree of intervals is used to convert both the uncertain inequality and equality constraints to deterministic inequality constraints. In doing so, an unconstrained deterministic optimization problem will be constructed in association with the penalty function method. The design will be finally formulated as a nested three-loop optimization, a class of highly challenging problems in the area of engineering design optimization. An advanced hierarchical optimization scheme is developed to solve the proposed optimization problem based on the multidisciplinary feasible strategy, which is a well-studied method able to reduce the dimensions of multidisciplinary design optimization problems by using the design variables as independent optimization variables. In the hierarchical optimization system, the non-dominated sorting genetic algorithm II, sequential quadratic programming method and Gauss-Seidel iterative approach are applied to the outer, middle and inner loops of the optimization problem, respectively. Typical numerical examples are used to demonstrate the effectiveness of the proposed methodology.

  12. long interval microtremor array survey in sedimentary basin

    NASA Astrophysics Data System (ADS)

    Yoshimi, M.; Sugiyama, T.

    2011-12-01

    Microtremor array survey is one of the easiest passive inspection methods to estimate the subsurface velocity structure of sedimentary basin. Since the method utilizes ambient noise, of which stochastic features are not always stable both spatially and temporally, longer observation interval is necessary to obtain reliable results. We conducted microtremor array surveys each observation interval is more than ten days to test robustness of the microtoremors (frequency range: 0.1 to 1 Hz) and phase velocities estimation. Velocity seismometers with natural period more than 5 sec. are deployed connected with 24 bit A/D, GPS time-calibrated data loggers. Each observation comprises of twelve stations arranged as three regular triangle arrays with radii several hundred meters to several kilometers to enable wide-band phase velocity estimation (0.1 to 1 Hz at maximum) necessary for Vs estimation at each site (south Niigata, central Japan). Each continuous data are segmented to hourly data sets, and they are analyzed with SPAC method to obtain phase velocity estimations. Estimated phase velocities are fluctuated especially in the lower frequency range (say, below 0.3 Hz). Our observation shows importance of longer interval observation to obtain reliable phase velocity estimates with microtremor array survey.

  13. Flood frequency analysis: Confidence interval estimation by test inversion bootstrapping

    NASA Astrophysics Data System (ADS)

    Schendel, Thomas; Thongwichian, Rossukon

    2015-09-01

    A common approach to estimate extreme flood events is the annual block maxima approach, where for each year the peak streamflow is determined and a distribution (usually the generalized extreme value distribution (GEV)) is fitted to this series of maxima. Eventually this distribution is used to estimate the return level for a defined return period. However, due to the finite sample size, the estimated return levels are associated with a range of uncertainity, usually expressed via confidence intervals. Previous publications have shown that existing bootstrapping methods for estimating the confidence intervals of the GEV yield too narrow estimates of these uncertainty ranges. Therefore, we present in this article a novel approach based on the less known test inversion bootstrapping, which we adapted especially for complex quantities like the return level. The reliability of this approach is studied and its performance is compared to other bootstrapping methods as well as the Profile Likelihood technique. It is shown that the new approach improves significantly the coverage of confidence intervals compared to other bootstrapping methods and for small sample sizes should even be favoured over the Profile Likelihood.

  14. Visual feedback for retuning to just intonation intervals

    NASA Astrophysics Data System (ADS)

    Ayers, R. Dean; Nordquist, Peter R.; Corn, Justin S.

    2005-04-01

    Musicians become used to equal temperament pitch intervals due to their widespread use in tuning pianos and other fixed-pitch instruments. For unaccompanied singing and some other performance situations, a more harmonious blending of sounds can be achieved by shifting to just intonation intervals. Lissajous figures provide immediate and striking visual feedback that emphasizes the frequency ratios and pitch intervals found among the first few members of a single harmonic series. Spirograph patterns (hypotrochoids) are also especially simple for ratios of small whole numbers, and their use for providing feedback to singers has been suggested previously [G. W. Barton, Jr., Am. J. Phys. 44(6), 593-594 (1976)]. A hybrid mixture of these methods for comparing two frequencies generates what appears to be a three dimensional Lissajous figure-a cylindrical wire mesh that rotates about its tilted vertical axis, with zero tilt yielding the familiar Lissajous figure. Sine wave inputs work best, but the sounds of flute, recorder, whistling, and a sung ``oo'' are good enough approximations to work well. This initial study compares the three modes of presentation in terms of the ease with which a singer can obtain a desired pattern and recognize its shape.

  15. Antimicrobial agents-associated with QT interval prolongation.

    PubMed

    Bril, Fernando; Gonzalez, Claudio Daniel; Di Girolamo, Guillermo

    2010-01-01

    QT interval prolongation is one of the most important causes of withdrawal of drugs from the market, due to its association with Torsades de Pointes (TdP), a potentially fatal arrhythmia. Although many antimicrobial drugs are capable of inducing this type of arrhythmia, the importance of this effect is usually underestimated. Macrolides, quinolones, azoles, pentamidine, protease inhibitors, antimalarial drugs and cotrimoxazole are the anti-infective agents more frequently associated with this adverse effect. Despite the fact that the risk of QT prolongation and TdP under single antimicrobial therapy is low, these drugs are so extensively used that sporadic cases of this arrhythmia are reported. Moreover, antimicrobial drugs are susceptible to pharmacokinetic and pharmacodynamic interactions with other drugs, which may increase the risk of this arrhythmia. Therefore, physicians must be familiar with not only the antimicrobial drugs capable of producing QT interval prolongation, but also their potential interactions. In addition, patient's specific risk factors of prolonging QT interval or producing TdP must be taken into account. This article reviews the role of anti-infective drugs in QT prolongation, focusing on QT prolongation mechanisms, potential drug interactions, and patients' predisposing factors to this arrhythmia. PMID:20210724

  16. The behavioral economics of choice and interval timing.

    PubMed

    Jozefowiez, J; Staddon, J E R; Cerutti, D T

    2009-07-01

    The authors propose a simple behavioral economic model (BEM) describing how reinforcement and interval timing interact. The model assumes a Weber-law-compliant logarithmic representation of time. Associated with each represented time value are the payoffs that have been obtained for each possible response. At a given real time, the response with the highest payoff is emitted. The model accounts for a wide range of data from procedures such as simple bisection, metacognition in animals, economic effects in free-operant psychophysical procedures, and paradoxical choice in double-bisection procedures. Although it assumes logarithmic time representation, it can also account for data from the time-left procedure usually cited in support of linear time representation. It encounters some difficulties in complex free-operant choice procedures, such as concurrent mixed fixed-interval schedules as well as some of the data on double bisection, which may involve additional processes. Overall, BEM provides a theoretical framework for understanding how reinforcement and interval timing work together to determine choice between temporally differentiated reinforcers.

  17. Nosewitness Identification: Effects of Lineup Size and Retention Interval

    PubMed Central

    Alho, Laura; Soares, Sandra C.; Costa, Liliana P.; Pinto, Elisa; Ferreira, Jacqueline H. T.; Sorjonen, Kimmo; Silva, Carlos F.; Olsson, Mats J.

    2016-01-01

    Although canine identification of body odor (BO) has been widely used as forensic evidence, the concept of nosewitness identification by human observers was only recently put to the test. The results indicated that BOs associated with male characters in authentic crime videos could later be identified in BO lineup tests well above chance. To further evaluate nosewitness memory, we assessed the effects of lineup size (Experiment 1) and retention interval (Experiment 2), using a forced-choice memory test. The results showed that nosewitness identification works for all lineup sizes (3, 5, and 8 BOs), but that larger lineups compromise identification performance in similarity to observations from eye- and earwitness studies. Also in line with previous eye- and earwitness studies, but in disagreement with some studies on odor memory, Experiment 2 showed significant forgetting between shorter retention intervals (15 min) and longer retention intervals (1-week) using lineups of five BOs. Altogether this study shows that identification of BO in a forensic setting is possible and has limits and characteristics in line with witness identification through other sensory modalities. PMID:27303317

  18. Income maximizing on concurrent ratio-interval schedules of reinforcement

    PubMed Central

    Shurtleff, David; Silberberg, Alan

    1990-01-01

    Three experiments examined the effect of food availability on pigeons' choice behavior under concurrent schedules of reinforcement. In Experiment 1, 3 pigeons earned their daily food ration by choosing, in 30-min sessions, between concurrent variable-ratio 30 variable-interval 40-s schedules. Food presentations during both schedules lasted 2 or 12 s, depending upon the condition. Relative variable-ratio response rate was inversely related to hopper duration. In Experiment 2, 4 pigeons received their daily feeding by responding on the same schedule pair as in Experiment 1 (with 4-s food presentations) in sessions that varied in length from 10 to 30 min, depending on the condition. The length of a vertical slit projected on a response key increased with time so that “passage of time” might be more easily discriminable. As session duration decreased, relative variable-ratio response rate increased. In Experiment 3, 4 pigeons chose between two variable-interval 40-s schedules. One schedule operated without regard to the schedule selected, whereas the other operated only when the subject responded in its presence (dependent). Although these schedules had the same feedback function, preference for the dependent variable interval increased as session duration decreased from 30 to 10 min. The preference changes in these studies reveal the operation of an income-maximizing process in choice. PMID:16812610

  19. Age effects in discrimination of intervals within rhythmic tone sequences.

    PubMed

    Fitzgibbons, Peter J; Gordon-Salant, Sandra

    2015-01-01

    This study measured listener sensitivity to increments of a target inter-onset interval (IOI) embedded within tone sequences that featured different rhythmic patterns. The sequences consisted of six 50-ms 1000-Hz tone bursts separated by silent intervals that were adjusted to create different timing patterns. Control sequences were isochronous, with all tonal IOIs fixed at either 200 or 400 ms, while other patterns featured combinations of the two IOIs arranged to create different sequential tonal groupings. Duration difference limens in milliseconds for increments of a single sequence IOI were measured adaptively by adjusting the duration of an inter-tone silent interval. Specific target IOIs within sequences differed across discrimination conditions. Listeners included younger normal-hearing adults and groups of older adults with and without hearing loss. Discrimination performance measured for each of the older groups of listeners was observed to be equivalent, with each group exhibiting significantly poorer discrimination performance than the younger listeners in each sequence condition. Additionally, the specific influence of variable rhythmic grouping on temporal sensitivity was found to be greatest among older listeners. PMID:25618068

  20. Confidence intervals for expected moments algorithm flood quantile estimates

    USGS Publications Warehouse

    Cohn, T.A.; Lane, W.L.; Stedinger, J.R.

    2001-01-01

    Historical and paleoflood information can substantially improve flood frequency estimates if appropriate statistical procedures are properly applied. However, the Federal guidelines for flood frequency analysis, set forth in Bulletin 17B, rely on an inefficient "weighting" procedure that fails to take advantage of historical and paleoflood information. This has led researchers to propose several more efficient alternatives including the Expected Moments Algorithm (EMA), which is attractive because it retains Bulletin 17B's statistical structure (method of moments with the Log Pearson Type 3 distribution) and thus can be easily integrated into flood analyses employing the rest of the Bulletin 17B approach. The practical utility of EMA, however, has been limited because no closed-form method has been available for quantifying the uncertainty of EMA-based flood quantile estimates. This paper addresses that concern by providing analytical expressions for the asymptotic variance of EMA flood-quantile estimators and confidence intervals for flood quantile estimates. Monte Carlo simulations demonstrate the properties of such confidence intervals for sites where a 25- to 100-year streamgage record is augmented by 50 to 150 years of historical information. The experiments show that the confidence intervals, though not exact, should be acceptable for most purposes.

  1. Systolic time intervals at rest and during exercise in sportsmen.

    PubMed

    Franculescu, V; Sallam, E B; Otoiu, M E

    1982-01-01

    The authors using non-invasive methods, have studied left ventricular performance at rest and during training of sportsmen, taking into consideration the period of activity (during resting, training and competition periods). The studied subjects belonged to three groups (football, basketball and athletics). They all had more than 5 years of performance training. The obtained values are compared with data obtained from a control group of untrained subjects in the same age group. Determination of systolic time intervals has been done using mechanophonocardiographic tracing, registered at rest and during various exercise intensities, measuring PEP, LVET and Weissler ratio. Obtained data have been correlated with oxygen consumption, heart rate and blood pressure. Systolic time intervals measured at rest have been compared with the values obtained by Weissler from untrained subjects. Regression equations are given for values obtained in exercise tests in the case of sportsmen as well as for sedentary persons. In conclusion the authors stress the importance of systolic time intervals determinations for indirect estimation of left ventricular performance at rest and during exercise tests. From the presented data results the importance of PEP and Weissler ratio, which parametres the authors recommend to be systematically determined in the case of performance sportsmen. The most significant modifications are recorded when values are compared for the same subject during all the three periods of activity.

  2. Delay of Feedback Interval, Postfeedback Interval, Distraction, and Task Difficulty as Factors in a Modified Concept-Identification Task with Junior High School Subjects

    ERIC Educational Resources Information Center

    Rabinowitz, F. Michael; Beaton, Virginia L.

    1971-01-01

    The effects of delay of information feedback interval (0 or 7 seconds), postinformation feedback interval (1, 8, or 15 seconds), difficulty (one or three variable irrelevant dimensions), and presence or absence of a tractor in the postinformation feedback interval were investigated with 240 junior high school children in a modified…

  3. Exact and Best Confidence Intervals for the Ability Parameter of the Rasch Model.

    ERIC Educational Resources Information Center

    Klauer, Karl Christoph

    1991-01-01

    Smallest exact confidence intervals for the ability parameter of the Rasch model are derived and compared to the traditional asymptotically valid intervals based on Fisher information. Tables of exact confidence intervals, termed Clopper-Pearson intervals, can be drawn up with a computer program developed by K. Klauer. (SLD)

  4. An Introduction to Confidence Intervals for Both Statistical Estimates and Effect Sizes.

    ERIC Educational Resources Information Center

    Capraro, Mary Margaret

    This paper summarizes methods of estimating confidence intervals, including classical intervals and intervals for effect sizes. The recent American Psychological Association (APA) Task Force on Statistical Inference report suggested that confidence intervals should always be reported, and the fifth edition of the APA "Publication Manual" (2001)…

  5. Bouts of Responding: The Relation between Bout Rate and the Rate of Variable-Interval Reinforcement

    ERIC Educational Resources Information Center

    Shull, Richard L.; Grimes, Julie A.; Bennett, J. Adam

    2004-01-01

    By nose poking a lighted key, rats obtained food pellets on either a variable- interval schedule of reinforcement or a schedule that required an average of four additional responses after the end of the variable-interval component (a tandem variable-interval variable-ratio 4 schedule). With both schedule types, the mean variable interval was…

  6. On Some Confidence Intervals for Estimating the Mean of a Skewed Population

    ERIC Educational Resources Information Center

    Shi, W.; Kibria, B. M. Golam

    2007-01-01

    A number of methods are available in the literature to measure confidence intervals. Here, confidence intervals for estimating the population mean of a skewed distribution are considered. This note proposes two alternative confidence intervals, namely, Median t and Mad t, which are simple adjustments to the Student's t confidence interval. In…

  7. The Prognostic Role of QTc Interval in Acute Myocarditis

    PubMed Central

    Hung, Yuan; Lin, Wei-Hsiang; Lin, Chin-Sheng; Cheng, Shu-Meng; Tsai, Tsung-Neng; Yang, Shih-Ping; Lin, Wen-Yu

    2016-01-01

    Background Acute myocarditis is an inflammatory disease of the myocardium. Although a fulminant course of the disease is difficult to predict, it may lead to acute heart failure and death. Previous studies have demonstrated that reduced left ventricular systolic function and prolonged QRS duration can predict the fulminant course of acute myocarditis. This study aimed to identify whether prolonged QTc interval could also be predictive of fulminant disease in this population. Methods We retrospectively included 40 patients diagnosed with acute myocarditis who were admitted to our hospital between 2002 and 2013. They were divided into the fulminant group (n = 9) and the non-fulminant group (n = 31). Clinical symptoms, laboratory findings, electrocardiographic, and echocardiographic parameters were analyzed. Multivariate logistic regression analysis was used to identify the independent factors predictive of fulminant disease. Results Patients with fulminant myocarditis had a higher mortality rate than those with non-fulminant disease (55.6% vs. 0%, p < 0.001). Multivariate analysis revealed that wider QRS durations (133.22 ± 45.85 ms vs. 92.81 ± 15.56 ms, p = 0.030) and longer QTc intervals (482.78 ± 69.76 ms vs. 412.00 ± 33.31 ms, p = 0.016) were significant predictors associated with a fulminant course of myocarditis. Conclusions Prolonged QRS duration and QTc interval, upon patient admission, may be associated with an increased risk of fulminant disease and increased in-hospital mortality. Therefore, early recognition of fulminant myocarditis and early mechanical support could provide improved patient outcomes. PMID:27122953

  8. Neural architecture of choice behaviour in a concurrent interval schedule.

    PubMed

    Kalenscher, Tobias; Diekamp, Bettina; Güntürkün, Onur

    2003-11-01

    Concurrent interval schedules are classic experimental paradigms that are traditionally employed in psychological research on choice behaviour. To analyse the neural basis of choice in a concurrent fixed interval schedule, pigeons were trained to peck on two response keys. Responses were differentially rewarded in key specific short or long time intervals (SI vs. LI). Using tetrodotoxin, we reversibly blocked the neostriatum caudolaterale (NCL, the avian functional equivalent of the prefrontal cortex), avian caudate-putamen and nucleus accumbens to examine their contribution. A detailed analysis of baseline choice behaviour revealed that response distribution and key affinity were determined by cued or time-related expectancy for rewards on the SI key. The pigeons' response frequency increased on the SI key and decreased on the LI key with increasing temporal proximity to the SI reward and pigeons switched to the LI key after reward delivery. Pecking bursts on the LI key were negatively correlated with bursts on the SI key. Neostriatum caudolaterale inactivation did not affect pecking activity per se but interfered with reward-related temporal modulation of pecking frequency, switching pattern and coupling of LI to SI pecks. Blockade of caudate-putamen resulted in a complete behavioural halt, while inactivation of nucleus accumbens diminished operant behaviour without affecting consummatory responses. These data suggest that the NCL is tuned via indirect striato-pallial projections to integrate cued or time-related reward expectancy into a response selection process in order to set, maintain or shift goals. The NCL possibly feeds forward the resulting motor commands to the caudate-putamen for execution.

  9. Prospective study of birth interval dynamics in rural Bangladesh.

    PubMed

    Chen, L C; Ahmed, S; Gesche, M; Henry Mosley, W

    1974-07-01

    Abstract A group of 209 married, fecund women in rural Bangladesh were studied prospectively for 24 months from 1969 to 1971 to define some of the biological and sociological factors relating to fertility performance. These women were selected from a larger study population of 112,000 that had been followed with a daily house-to-house vital registration programme since 1966. The selected women were interviewed bi-weekly and were asked questions about menstruation, pregnancy, lactation, husband's occupational absences, and monthly urine tests for pregnancy were taken. The results for 193 non-contracepting women revealed that the seasonal pattern of births previously observed in this population could be associated with a corresponding seasonal pattern of conceptions and that this was due to a seasonal trend in fecundability. The highest conception rates were in the coolest months of the year. Post-partum lactational amenorrhoea was very prolonged, averaging 17 months for women with a surviving child. The appearance of the first post-partum menstrual flow (onset of ovulation) also had a seasonal trend which could not be adequately explained. The median waiting time to conception, once menstruation had resumed was eight months. This interval was influenced by seasonal fluctuations, as well as by the age of women and by husbands' absences. The foetal wastage rate was 15·0 per 100 conceptions, with 62 per cent of the foetal losses occurring during the second month of gestation. Overall, the average birth interval was 33 months, with the prolonged lactational amenorrhoea accounting for almost 45 per cent of this interval. From the Department of Population Dynamics, Johns Hopkins University, School of Hygiene and Public Health, Baltimore, Maryland 21205. PMID:22070207

  10. Inference by eye: reading the overlap of independent confidence intervals.

    PubMed

    Cumming, Geoff

    2009-01-30

    When 95 per cent confidence intervals (CIs) on independent means do not overlap, the two-tailed p-value is less than 0.05 and there is a statistically significant difference between the means. However, p for non-overlapping 95 per cent CIs is actually considerably smaller than 0.05: If the two CIs just touch, p is about 0.01, and the intervals can overlap by as much as about half the length of one CI arm before p becomes as large as 0.05. Keeping in mind this rule-that overlap of half the length of one arm corresponds approximately to statistical significance at p = 0.05-can be helpful for a quick appreciation of figures that display CIs, especially if precise p-values are not reported. The author investigated the robustness of this and similar rules, and found them sufficiently accurate when sample sizes are at least 10, and the two intervals do not differ in width by more than a factor of 2. The author reviewed previous discussions of CI overlap and extended the investigation to p-values other than 0.05 and 0.01. He also studied 95 per cent CIs on two proportions, and on two Pearson correlations, and found similar rules apply to overlap of these asymmetric CIs, for a very broad range of cases. Wider use of figures with 95 per cent CIs is desirable, and these rules may assist easy and appropriate understanding of such figures.

  11. A Constraint-based Attribute and Interval Planning

    NASA Technical Reports Server (NTRS)

    Frank, Jeremy; Jonsson, Ari; Clancy, Daniel (Technical Monitor)

    2001-01-01

    In this paper we introduce Constraint-based Attribute and Interval Planning (CAIP), a new paradigm for representing and reasoning about plans. The paradigm enables the description of planning domains with time, resources, concurrent activities, mutual exclusions among sets of activities, disjunctive preconditions and conditional effects. We provide a theoretical foundation for the paradigm using a mapping to first order logic. We also show that CAIP plans are naturally expressed by networks of constraints, and that planning maps directly to dynamic constraint reasoning. In addition, we show how constraint templates are used to provide a compact mechanism for describing planning domains.

  12. Methodological issues for determining intervals of subsequent cancer screening

    PubMed Central

    Bae, Jong-Myon

    2014-01-01

    The gap between nationwide recommendations of cancer screening and the related evidences obtained from Korean adults should be filled. Estimation of the mean sojourn time (MST) in a specific cancer is important to determine the intervals of subsequent screening. This author arranged the methods for calculating MST into 5 categories based on the parameters used. Under the legal barrier for protection of individual privacy and confidentiality in a Korean academic situation, the methods involving the use of transition rates or prevalence/incidence ratio would be applicable among these methods. PMID:25078383

  13. Geometric representation of interval exchange maps over algebraic number fields

    NASA Astrophysics Data System (ADS)

    Poggiaspalla, G.; Lowenstein, J. H.; Vivaldi, F.

    2008-01-01

    This paper is concerned with the restriction of interval exchange transformations (IETs) to algebraic number fields, which leads to maps on lattices. We characterize renormalizability arithmetically and study its relationships with a geometrical quantity that we call the drift vector. We exhibit some examples of renormalizable IETs with zero and non-zero drift vectors and carry out some investigations of their properties. In particular we look for evidence of the finite decomposition property on a family of IETs extending the example studied in Lowenstein et al (2007 Dyn. Syst. 22 73-106).

  14. On ``Overestimation-free Computational Version of Interval Analysis''

    NASA Astrophysics Data System (ADS)

    Popova, Evgenija D.

    2013-10-01

    The transformation of interval parameters into trigonometric functions, proposed in Int. J. Comput. Meth. Eng. Sci. Mech., vol. 13, pp. 319-328 (2012), is not motivated in comparison to the infinitely many equivalent algebraic transformations. The conclusions about the efficacy of the methodology used are based on incorrect comparisons between solutions of different problems. We show theoretically, and in the examples considered in the commented article, that changing the number of the parameters in a system of linear algebraic equations may change the initial problem, respectively, its solution set. We also correct various misunderstandings and bugs that appear in the article noted above.

  15. Onset of negative interspike interval correlations in adapting neurons.

    PubMed

    Urdapilleta, Eugenio

    2011-10-01

    Negative serial correlations in single spike trains are an effective method to reduce the variability of spike counts. One of the factors contributing to the development of negative correlations between successive interspike intervals is the presence of adaptation currents. In this work, based on a hidden Markov model and a proper statistical description of conditional responses, we obtain analytically these correlations in an adequate dynamical neuron model resembling adaptation. We derive the serial correlation coefficients for arbitrary lags, under a small adaptation scenario. In this case, the behavior of correlations is universal and depends on the first-order statistical description of an exponentially driven time-inhomogeneous stochastic process.

  16. Acoustic analysis of musical intervals in modern Byzantine Chant scales.

    PubMed

    Delviniotis, Dimitrios; Kouroupetroglou, Georgios; Theodoridis, Sergios

    2008-10-01

    The goal of this work is to investigate experimentally the music intervals in modern Byzantine Chant performance and to compare the obtained results with the equal temperament scales introduced by the Patriarchal Music Committee (PMC). Current measurements resulted from pressure and electroglottographic recordings of 13 famous chanters singing scales of all the music genera. The scales' microintervals were derived after pitch detection based on autocorrelation, cepstrum, and harmonic product spectrum analysis. The microintervallic differences between the experimental values and the PMC's ones were statistically analyzed indicating large deviation of the mean values and the standard deviations. Significant interaction effects were identified among some genera and between ascending and descending scale directions.

  17. Interval Throwing and Hitting Programs in Baseball: Biomechanics and Rehabilitation.

    PubMed

    Chang, Edward S; Bishop, Meghan E; Baker, Dylan; West, Robin V

    2016-01-01

    Baseball injuries from throwing and hitting generally occur as a consequence of the repetitive and high-energy motions inherent to the sport. Biomechanical studies have contributed to understanding the pathomechanics leading to injury and to the development of rehabilitation programs. Interval-based throwing and hitting programs are designed to return an athlete to competition through a gradual progression of sport-specific exercises. Proper warm-up and strict adherence to the program allows the athlete to return as quickly and safely as possible.

  18. Interspike interval statistics of neurons driven by colored noise.

    PubMed

    Lindner, Benjamin

    2004-02-01

    A perfect integrate-and-fire model driven by colored noise is studied by means of the interspike interval (ISI) density and the serial correlation coefficient. Exact and approximate expressions for these functions are derived for weak dichotomous or Gaussian noise, respectively. It is shown that correlations in the input result in positive correlations in the ISI sequence and in a reduction of ISI variability. The results also indicate that for weak noise, the noise distribution only shapes the ISI density but not the ISI correlations which are determined by the noise's correlation function.

  19. Interval Throwing and Hitting Programs in Baseball: Biomechanics and Rehabilitation.

    PubMed

    Chang, Edward S; Bishop, Meghan E; Baker, Dylan; West, Robin V

    2016-01-01

    Baseball injuries from throwing and hitting generally occur as a consequence of the repetitive and high-energy motions inherent to the sport. Biomechanical studies have contributed to understanding the pathomechanics leading to injury and to the development of rehabilitation programs. Interval-based throwing and hitting programs are designed to return an athlete to competition through a gradual progression of sport-specific exercises. Proper warm-up and strict adherence to the program allows the athlete to return as quickly and safely as possible. PMID:26991569

  20. Interval Prediction of Molecular Properties in Parametrized Quantum Chemistry

    NASA Astrophysics Data System (ADS)

    Edwards, David E.; Zubarev, Dmitry Yu.; Packard, Andrew; Lester, William A.; Frenklach, Michael

    2014-06-01

    The accurate evaluation of molecular properties lies at the core of predictive physical models. Most reliable quantum-chemical calculations are limited to smaller molecular systems while purely empirical approaches are limited in accuracy and reliability. A promising approach is to employ a quantum-mechanical formalism with simplifications and to compensate for the latter with parametrization. We propose a strategy of directly predicting the uncertainty interval for a property of interest, based on training-data uncertainties, which sidesteps the need for an optimum set of parameters.

  1. Design of time interval generator based on hybrid counting method

    NASA Astrophysics Data System (ADS)

    Yao, Yuan; Wang, Zhaoqi; Lu, Houbing; Chen, Lian; Jin, Ge

    2016-10-01

    Time Interval Generators (TIGs) are frequently used for the characterizations or timing operations of instruments in particle physics experiments. Though some "off-the-shelf" TIGs can be employed, the necessity of a custom test system or control system makes the TIGs, being implemented in a programmable device desirable. Nowadays, the feasibility of using Field Programmable Gate Arrays (FPGAs) to implement particle physics instrumentation has been validated in the design of Time-to-Digital Converters (TDCs) for precise time measurement. The FPGA-TDC technique is based on the architectures of Tapped Delay Line (TDL), whose delay cells are down to few tens of picosecond. In this case, FPGA-based TIGs with high delay step are preferable allowing the implementation of customized particle physics instrumentations and other utilities on the same FPGA device. A hybrid counting method for designing TIGs with both high resolution and wide range is presented in this paper. The combination of two different counting methods realizing an integratable TIG is described in detail. A specially designed multiplexer for tap selection is emphatically introduced. The special structure of the multiplexer is devised for minimizing the different additional delays caused by the unpredictable routings from different taps to the output. A Kintex-7 FPGA is used for the hybrid counting-based implementation of a TIG, providing a resolution up to 11 ps and an interval range up to 8 s.

  2. Recurrence Interval and Event Age Data for Type A Faults

    USGS Publications Warehouse

    Dawson, Timothy E.; Weldon, Ray J.; Biasi, Glenn P.

    2008-01-01

    This appendix summarizes available recurrence interval, event age, and timing of most recent event data for Type A faults considered in the Earthquake Rate Model 2 (ERM 2) and used in the ERM 2 Appendix C analysis as well as Appendix N (time-dependent probabilities). These data have been compiled into an Excel workbook named Appendix B A-fault event ages_recurrence_V5.0 (herein referred to as the Appendix B workbook). For convenience, the Appendix B workbook is attached to the end of this document as a series of tables. The tables within the Appendix B workbook include site locations, event ages, and recurrence data, and in some cases, the interval of time between earthquakes is also reported. The Appendix B workbook is organized as individual worksheets, with each worksheet named by fault and paleoseismic site. Each worksheet contains the site location in latitude and longitude, as well as information on event ages, and a summary of recurrence data. Because the data has been compiled from different sources with different presentation styles, descriptions of the contents of each worksheet within the Appendix B spreadsheet are summarized.

  3. Trial order and retention interval in human predictive judgment.

    PubMed

    Stout, Steven C; Amundson, Jeffrey C; Miller, Ralph R

    2005-12-01

    The influences of order of trial type and retention interval on human predictive judgments were assessed for a cue that was reinforced on half of its training presentations. Subjects observed 10 cue-outcome presentations (i.e., reinforced trials) and 10 cue-alone presentations (i.e., nonreinforced trials) in one of three different orders: all nonreinforced trials followed by all reinforced trials(latent inhibition), reinforced and nonreinforced trials interspersed (partial reinforcement), or al lreinforced trials followed by all nonreinforced trials (extinction). Ratings were based mainly on the most recent event type (i.e., a recency effect) when the test occurred immediately after training but were based mainly on initial event types (i.e., a primacy effect) when the test occurred after a 48-h delay. The subjects tested both immediately and with a long retention interval did not exhibit this shift to primacy (i.e., the recency effect persisted). These results demonstrate noncatastrophic forgetting and the flexible use of trial order information in predictive judgments.

  4. An absolute interval scale of order for point patterns

    PubMed Central

    Protonotarios, Emmanouil D.; Baum, Buzz; Johnston, Alan; Hunter, Ginger L.; Griffin, Lewis D.

    2014-01-01

    Human observers readily make judgements about the degree of order in planar arrangements of points (point patterns). Here, based on pairwise ranking of 20 point patterns by degree of order, we have been able to show that judgements of order are highly consistent across individuals and the dimension of order has an interval scale structure spanning roughly 10 just-notable-differences (jnd) between disorder and order. We describe a geometric algorithm that estimates order to an accuracy of half a jnd by quantifying the variability of the size and shape of spaces between points. The algorithm is 70% more accurate than the best available measures. By anchoring the output of the algorithm so that Poisson point processes score on average 0, perfect lattices score 10 and unit steps correspond closely to jnds, we construct an absolute interval scale of order. We demonstrate its utility in biology by using this scale to quantify order during the development of the pattern of bristles on the dorsal thorax of the fruit fly. PMID:25079866

  5. Interval time-place learning in young children.

    PubMed

    Thorpe, Christina M; Hallett, Darcy; Murphy, Melanie; Fitzpatrick, Cheryll L; Bakhtiar, Aishah

    2012-10-01

    While previous research has investigated the ability of animals to learn the spatial and temporal contingencies of biologically significant events (known as time-place learning), this ability has not been studied in humans. Children ranging from 5 to 10 years old were tested on a modified interval time-place learning task using a touchscreen computer. Results demonstrate the children were able to quickly learn both the timing and the sequence of this task. Despite a lack of anticipation on baseline trials, the children continued to follow the spatio-temporal contingencies in probe sessions where these contingencies were removed. Performance on the probe sessions provide strong evidence that the children had learned the spatio-temporal contingencies. Future research is needed to determine what age-related changes in iTPL occur. Furthermore, it is argued that this procedure can be used to extend interval timing in research in children, including, but not limited to, investigation of scalar timing with longer durations than have previously been investigated.

  6. Analysing uncertainties: Towards comparing Bayesian and interval probabilities'

    NASA Astrophysics Data System (ADS)

    Blockley, David

    2013-05-01

    Two assumptions, commonly made in risk and reliability studies, have a long history. The first is that uncertainty is either aleatoric or epistemic. The second is that standard probability theory is sufficient to express uncertainty. The purposes of this paper are to provide a conceptual analysis of uncertainty and to compare Bayesian approaches with interval approaches with an example relevant to research on climate change. The analysis reveals that the categorisation of uncertainty as either aleatoric or epistemic is unsatisfactory for practical decision making. It is argued that uncertainty emerges from three conceptually distinctive and orthogonal attributes FIR i.e., fuzziness, incompleteness (epistemic) and randomness (aleatory). Characterisations of uncertainty, such as ambiguity, dubiety and conflict, are complex mixes of interactions in an FIR space. To manage future risks in complex systems it will be important to recognise the extent to which we 'don't know' about possible unintended and unwanted consequences or unknown-unknowns. In this way we may be more alert to unexpected hazards. The Bayesian approach is compared with an interval probability approach to show one way in which conflict due to incomplete information can be managed.

  7. On Efficient Confidence Intervals for the Log-Normal Mean

    NASA Astrophysics Data System (ADS)

    Chami, Peter; Antoine, Robin; Sahai, Ashok

    Data obtained in biomedical research is often skewed. Examples include the incubation period of diseases like HIV/AIDS and the survival times of cancer patients. Such data, especially when they are positive and skewed, is often modeled by the log-normal distribution. If this model holds, then the log transformation produces a normal distribution. We consider the problem of constructing confidence intervals for the mean of the log-normal distribution. Several methods for doing this are known, including at least one estimator that performed better than Coxxs method for small sample sizes. We also construct a modified version of Coxxs method. Using simulation, we show that, when the sample size exceeds 30, it leads to confidence intervals that have good overall properties and are better than Coxxs method. More precisely, the actual coverage probability of our method is closer to the nominal coverage probability than is the case with Coxxs method. In addition, the new method is computationally much simpler than other well-known methods.

  8. Diminishing blocking interval in particle-conveying channel bundles

    NASA Astrophysics Data System (ADS)

    Barré, Chloé; Talbot, Julian

    2016-09-01

    We consider a channel bundle consisting of N c parallel channels conveying a particulate flux. Particles enter these channels according to a homogeneous Poisson process and exit after a fixed transit time, τ. An individual channel blocks if N particles are simultaneously present. When a channel is blocked the flux previously entering it is redistributed evenly over the remaining open channels. We perform event driven simulations to examine the behaviour of an initially empty channel bundle with a total entering flux of intensity Λ. The mean blockage time of the kth channel is denoted by ⟨ t k ⟩ ,k = 1 , ... , N c . For N = 1, as shown previously, the interval between successive blockages is constant, while for N > 1 an accelerating cascade, i.e. one in which the interval between successive blockages decreases, is observed. After an initial transient regime we observe a well-defined universal regime that is characterized by Δ_k^{(N)} = (-1)^{N-1}[(N-1)!]^2/(Λτ)^N Δ k ( N ) = ( - 1 ) N - 1 [ ( N - 1 ) ! ] 2 ( Λ τ ) N where Δ_k^{(1)}=< t_k rangle-< t_{k-1}rangle}Δk(1)=⟨tk⟩-⟨tk-1⟩ and {Δ_k^{(j)}=Δ_k^{(j-1)}-Δ_{k-1}^{(j-1)}Δk(j)=Δk(j-1)-Δk-1(j-1) denotes the jth order difference.

  9. Statistical Properties of the Interbeat Interval Cascade in Human Hearts

    NASA Astrophysics Data System (ADS)

    Ghasemi, Fatemeh; Peinke, J.; Reza Rahimi Tabar, M.; Sahimi, Muhammad

    Statistical properties of interbeat intervals cascade in human hearts are evaluated by considering the joint probability distribution P (Δx2, τ2 Δx1, τ1) for two interbeat increments Δx1 and Δx2 of different time scales τ1 and τ2. We present evidence that the conditional probability distribution P (Δx2, τ2 | Δx1, τ1) may be described by a Chapman-Kolmogorov equation. The corresponding Kramers-Moyal (KM) coefficients are evaluated. The analysis indicates that while the first and second KM coefficients take on well-defined and significant values, the higher-order coefficients in the KM expansion are small. As a result, the joint probability distributions of the increments in the interbeat intervals are described by a Fokker-Planck equation, with the first two KM coefficients acting as the drift and diffusion coefficients. The method provides a novel technique for distinguishing two classes of subjects, namely, healthy ones and those with congestive heart failure, in terms of the drift and diffusion coefficients which behave differently for two classes of the subjects.

  10. Strontium isotope geochronology of selected intervals within the Florida Neogene

    SciTech Connect

    Jones, D.S.; Mueller, P.A.; Hodell, D.A.; Stanley, L.A. . Dept. of Geology)

    1993-03-01

    The Neogene stratigraphic record of Florida reveals many richly fossiliferous (both invertebrate and vertebrate), shallow-marine deposits whose ages are poorly constrained, despite over a century of paleontological investigation. Chronostratigraphic analyses are frequently hampered by a general absence of age-diagnostic fossils (micro- or nannofossils in particular), laterally discontinuous sedimentary units, and an overall lack of natural exposure. Consequently, temporal correlations among many of Florida's Neogene units as well as with the global geomagnetic polarity timescale (GPTS) remain tenuous. Strontium isotope ([sup 87]Sr/[sup 86]Sr) geochronology offers considerable potential as an independent method for correlating these deposits with one another as well as with the GPTS. Portions of the Miocene and Pliocene as well as most of the Pleistocene were characterized by rapid increases in the global [sup 87]Sr/[sup 86]Sr of seawater. Marine carbonates formed within these intervals are therefore particularly amenable to investigation by Sr isotope techniques. Ratios ([sup 87]Sr/[sup 86]Sr) from mollusk shells collected throughout Florida within stratigraphic context ranged from 0.70785 which roughly correspond to the interval 30 Ma (late Oligocene) to 1 Ma (late Pleistocene). The data suggest that many accepted correlations based on lithologic and/or faunal similarities within Florida's Miocene and Plio-Pleistocene strata are improbable. While additional sampling is in order, improved correlation between vertebrate and invertebrate biochronologies has already resulted from the stratigraphic based upon this approach.

  11. Spectral Methods Using Rational Basis Functions on an Infinite Interval

    NASA Astrophysics Data System (ADS)

    Boyd, John P.

    1987-03-01

    By using the map y = L cot( t) where L is a constant, differential equations on the interval yɛ [- ∞, ∞] can be transformed into tɛ [0, π] and solved by an ordinary Fourier series. In this article, earlier work by Grosch and Orszag ( J. Comput. Phys.25, 273 (1977)), Cain, Ferziger, and Reynolds ( J. Comput. Phys.56, 272 (1984)), and Boyd ( J. Comput. Phys.25, 43 (1982); 57, 454 (1985); SIAM J. Numer. Anal. (1987)) is extended in several ways. First, the series of orthogonal rational functions converge on the exterior of bipolar coordinate surfaces in the complex y-plane. Second, Galerkin's method will convert differential equations with polynomial or rational coefficients into banded matrix problems. Third, with orthogonal rational functions it is possible to obtain exponential convergence even for u( y) that asymptote to a constant although this behavior would wreck alternatives such as Hermite or sinc expansions. Fourth, boundary conditions are usually "natural" rather than "essential" in the sense that the singularities of the differential equation will force the numerical solution to have the correct behavior at infinity even if no constraints are imposed on the basis functions. Fifth, mapping a finite interval to an infinite one and then applying the rational Chebyshev functions gives an exponentially convergent method for functions with bounded endpoint singularities. These concepts are illustrated by five numerical examples.

  12. Bridging the interval: theory and neurobiology of trace conditioning.

    PubMed

    Raybuck, Jonathan D; Lattal, K Matthew

    2014-01-01

    An early finding in the behavioral analysis of learning was that conditioned responding weakens as the conditioned stimulus (CS) and unconditioned stimulus (US) are separated in time. This "trace" conditioning effect has been the focus of years of research in associative learning. Theoretical accounts of trace conditioning have focused on mechanisms that allow associative learning to occur across long intervals between the CS and US. These accounts have emphasized degraded contingency effects, timing mechanisms, and inhibitory learning. More recently, study of the neurobiology of trace conditioning has shown that even a short interval between the CS and US alters the circuitry recruited for learning. Here, we review some of the theoretical and neurobiological mechanisms underlying trace conditioning with an emphasis on recent studies of trace fear conditioning. Findings across many studies have implications not just for how we think about time and conditioning, but also for how we conceptualize fear conditioning in general, suggesting that circuitry beyond the usual suspects needs to be incorporated into current thinking about fear, learning, and anxiety. PMID:24036411

  13. Concurrent random-interval schedules and the matching law.

    PubMed

    Rodewald, H K

    1978-11-01

    In Experiment I, a group of eight pigeons performed on concurrent random-interval schedules constructed by holding probability equal and varying cycle time to produce ratios of reinforcer densities of 1:1, 3:1, and 5:1 for key pecking. Schedules for a second group of seven were constructed with equal cycle times and unequal probabilities. Both groups deviated from simple matching, but the two forms of the schedules appeared to produce no consistent patterns of deviation. The data were found to be consistent with those obtained in concurrent variable-interval situations. The parameters of the matching equation in the form of Y=k X(a) were estimated; the value of k was unity and a was 0.84. In Experiment II, six pigeons were exposed to two conc RI RI schedules in which one component increasingly approximated an FI schedule. The value of k was not 1.0. Concurrent RI RI schedules were shown to represent a continuum from conc FI VI to conc VI VI schedules. The use of the exponential equation in testing "matching laws" suggests that a<1 will continue to be observed, and this will set limits on the form of new laws and the assumed or rational values of the component variables in these laws.

  14. Acute effects of intense interval training on running mechanics.

    PubMed

    Collins, M H; Pearsall, D J; Zavorsky, G S; Bateni, H; Turcotte, R A; Montgomery, D L

    2000-02-01

    The aims of this study were to determine if there are significant kinematic changes in running pattern after intense interval workouts, whether duration of recovery affects running kinematics, and whether changes in running economy are related to changes in running kinematics. Seven highly trained male endurance runners (VO2max = 72.3+/-3.3 ml x kg(-1) x min(-1); mean +/- s) performed three interval running workouts of 10 x 400 m at a speed of 5.94+/-0.19 m x s(-1) (356+/-11.2 m x min(-1)) with a minimum of 4 days recovery between runs. Recovery of 60, 120 or 180 s between each 400 m repetition was assigned at random. Before and after each workout, running economy and several kinematic variables were measured at speeds of 3.33 and 4.47 m x s(-1) (200 and 268 m x min(-1)). Speed was found to have a significant effect on shank angle, knee velocity and stride length (P < 0.05). Correlations between changes pre- and post-test for VO2 (ml x kg(-1) x min(-1)) and several kinematic variables were not significant (P > 0.05) at both speeds. In general, duration of recovery was not found to adversely affect running economy or the kinematic variables assessed, possibly because of intra-individual adaptations to fatigue.

  15. Perception of relative depth interval: systematic biases in perceived depth.

    PubMed

    Harris, Julie M; Chopin, Adrien; Zeiner, Katharina; Hibbard, Paul B

    2012-01-01

    Given an estimate of the binocular disparity between a pair of points and an estimate of the viewing distance, or knowledge of eye position, it should be possible to obtain an estimate of their depth separation. Here we show that, when points are arranged in different vertical geometric configurations across two intervals, many observers find this task difficult. Those who can do the task tend to perceive the depth interval in one configuration as very different from depth in the other configuration. We explore two plausible explanations for this effect. The first is the tilt of the empirical vertical horopter: Points perceived along an apparently vertical line correspond to a physical line of points tilted backwards in space. Second, the eyes can rotate in response to a particular stimulus. Without compensation for this rotation, biases in depth perception would result. We measured cyclovergence indirectly, using a standard psychophysical task, while observers viewed our depth configuration. Biases predicted from error due either to cyclovergence or to the tilted vertical horopter were not consistent with the depth configuration results. Our data suggest that, even for the simplest scenes, we do not have ready access to metric depth from binocular disparity.

  16. Concept of a (1-. cap alpha. ) performance confidence interval

    SciTech Connect

    Leong, H.H.; Johnson, G.R.; Bechtel, T.N.

    1980-01-01

    A multi-input, single-output system is assumed to be represented by some model. The distribution functions of the input and the output variables are considered to be at least obtainable through experimental data. Associated with the computer response of the model corresponding to given inputs, a conditional pseudoresponse set is generated. This response can be constructed by means of the model by using the simulated pseudorandom input variates from a neighborhood defined by a preassigned probability allowance. A pair of such pseudoresponse values can then be computed by a procedure corresponding to a (1-..cap alpha..) probability for the conditional pseudoresponse set. The range defined by such a pair is called a (1-..cap alpha..) performance confidence interval with respect to the model. The application of this concept can allow comparison of the merit of two models describing the same system, or it can detect a system change when the current response is out of the performance interval with respect to the previously identified model. 6 figures.

  17. Off-axis angular spectrum method with variable sampling interval

    NASA Astrophysics Data System (ADS)

    Kim, Yong-Hae; Byun, Chun-Won; Oh, Himchan; Pi, Jae-Eun; Choi, Ji-Hun; Kim, Gi Heon; Lee, Myung-Lae; Ryu, Hojun; Hwang, Chi-Sun

    2015-08-01

    We proposed a novel off-axis angular spectrum method (ASM) for simulating free space wave propagation with a large shifted destination plane. The off-axis numerical simulation took wave propagation between a parallel source and a destination plane, but a destination plane was shifted from a source plane. The shifted angular spectrum method was proposed for diffraction simulation with a shifted destination plane and satisfied the Nyquist condition for sampling by limiting a bandwidth of a propagation field to avoid an aliasing error due to under sampling. However, the effective sampling number of the shifted ASM decreased when the shifted distance of the destination plane was large which caused a numerical error in the diffraction simulation. To compensate for the decrease of an effective sampling number for the large shifted destination plane, we used a variable sampling interval in a Fourier space to maintain the same effective sampling number independent of the shifted distance of the destination plane. As a result, our proposed off-axis ASM with a variable sampling interval can produce simulation results with high accuracy for nearly every shifted distance of a destination plane when an off-axis angle is less than 75°. We compared the performances of the off-axis ASM using the Chirp Z transform and non-uniform FFT for implementing a variable spatial frequency in a Fourier space.

  18. QT interval in children with sensory neural hearing loss.

    PubMed

    El Habbal, Magdi H; Mahoney, C O

    2002-04-01

    Long QT syndrome was first described in children with congenital sensory neural hearing loss (SNHL). The deafness was attributed to abnormalities in potassium ion channels of the inner ear. Similar channels are present in the heart and its dysfunction causes long QT syndrome. Whether congenital SNHL is associated with prolonged QT is unknown. This study examined 52 patients (median age 8.35 years, range 0.21-17.42 years) with SNHL and compared them to 63 healthy children (median age 10.2 years; range 0.67-19 years). An observer, who was blinded from the presence or absence of SNHL, measured QT, QTc intervals and dispersions from a standard 12-lead electrocardiogram. To assess the cardiac autonomic enervation, power spectral analysis of heart rate variability was determined using a 24-hour ambulatory heart rate monitor and was expressed as high (HF) to low frequency (LF) ratio. Left ventricular size and functions were evaluated by using two-dimensional echocardiography. The medians (and ranges) of QT intervals were 340 ms (230-420 ms) in patients and 320 ms (240-386 ms) in the control group (P < 0.01). The QTc was longer in patients with SNHL (median 417 ms, range 384-490 ms) than in controls (median 388 ms, range 325-432 ms, P < 0.001). QT dispersions in SNHL were higher (median .038 ms, range 00-11 ms) than controls (median 27 ms, range 00-52 ms, P < 0.001). T wave inversion (n = 16) and alternans (n = 3) occurred in patients with SNHL. Heart rates were similar in both groups. Some deaf patients (n = 8) had dizzy episodes with a QTc > 440 ms. The HF:LF ratio was 1.32 (0.516-2.33) in deaf patients and 1.428 (0.67-2.3) in the control group (P > 0.1). Left ventricular size and functions were similar and normal in deaf patients and controls. In children, congenital SNHL is associated with a prolonged QT interval. PMID:11991368

  19. Stability of heartbeat interval distributions in chronic high altitude hypoxia.

    PubMed

    Meyer, M; Rahmel, A; Marconi, C; Grassi, B; Cerretelli, P; Skinner, J E

    1998-01-01

    Recent studies of nonlinear dynamics of the long-term variability of heart rate have identified nontrivial long-range correlations and scale-invariant power-law characteristics (l/f noise) that were remarkably consistent between individuals and were unrelated to external or environmental stimuli (Meyer et al., 1998a). The present analysis of complex nonstationary heartbeat patterns is based on the sequential application of the wavelet transform for elimination of local polynomial nonstationary behavior and an analytic signal approach by use of the Hilbert transform (Cumulative Variation Amplitude Analysis). The effects of chronic high altitude hypoxia on the distributions and scaling functions of cardiac intervals over 24 hr epochs and 4 hr day/nighttime subepochs were determined from serial heartbeat interval time series of digitized 24 hr ambulatory ECGs recorded in 9 healthy subjects (mean age 34 yrs) at sea level and during a sojourn at high altitude (5,050 m) for 34 days (Ev-K2-CNR Pyramid Laboratory, Sagarmatha National Park, Nepal). The results suggest that there exists a hidden, potentially universal, common structure in the heterogeneous time series. A common scaling function with a stable Gamma distribution defines the probability density of the amplitudes of the fluctuations in the heartbeat interval time series of individual subjects. The appropriately rescaled distributions of normal subjects at sea level demonstrated stable Gamma scaling consistent with a single scaled plot (data collapse). Longitudinal assessment of the rescaled distributions of the 24 hr recordings of individual subjects showed that the stability of the distributions was unaffected by the subject's exposure to a hypobaric (hypoxic) environment. The rescaled distributions of 4 hr subepochs showed similar scaling behavior with a stable Gamma distribution indicating that the common structure was unequivocally applicable to both day and night phases and, furthermore, did not undergo

  20. Acceptability of Flight Deck-Based Interval Management Crew Procedures

    NASA Technical Reports Server (NTRS)

    Murdock, Jennifer L.; Wilson, Sara R.; Hubbs, Clay E.; Smail, James W.

    2013-01-01

    The Interval Management for Near-term Operations Validation of Acceptability (IM-NOVA) experiment was conducted at the National Aeronautics and Space Administration (NASA) Langley Research Center (LaRC) in support of the NASA Next Generation Air Transportation System (NextGen) Airspace Systems Program's Air Traffic Management Technology Demonstration - 1 (ATD-1). ATD-1 is intended to showcase an integrated set of technologies that provide an efficient arrival solution for managing aircraft using NextGen surveillance, navigation, procedures, and automation for both airborne and ground-based systems. The goal of the IM-NOVA experiment was to assess if procedures outlined by the ATD-1 Concept of Operations, when used with a minimum set of Flight deck-based Interval Management (FIM) equipment and a prototype crew interface, were acceptable to and feasible for use by flight crews in a voice communications environment. To investigate an integrated arrival solution using ground-based air traffic control tools and aircraft automatic dependent surveillance broadcast (ADS-B) tools, the LaRC FIM system and the Traffic Management Advisor with Terminal Metering and Controller Managed Spacing tools developed at the NASA Ames Research Center (ARC) were integrated in LaRC's Air Traffic Operations Laboratory. Data were collected from 10 crews of current, qualified 757/767 pilots asked to fly a high-fidelity, fixed based simulator during scenarios conducted within an airspace environment modeled on the Dallas-Fort Worth (DFW) Terminal Radar Approach Control area. The aircraft simulator was equipped with the Airborne Spacing for Terminal Area Routes algorithm and a FIM crew interface consisting of electronic flight bags and ADS-B guidance displays. Researchers used "pseudo-pilot" stations to control 24 simulated aircraft that provided multiple air traffic flows into DFW, and recently retired DFW air traffic controllers served as confederate Center, Feeder, Final, and Tower

  1. Naming, rehearsal, and interstimulus interval effects in memory processing.

    PubMed

    Wright, A A; Cook, R G; Rivera, J J; Shyan, M R; Neiworth, J J; Jitsumori, M

    1990-11-01

    Recognition memory was tested for lists of 6 briefly (0.08 s) presented pictures at different interstimulus intervals (ISI) of 0.08, 1, and 4 s. Experiment 1 showed a 16% performance increase (ISI effect) for increasing ISI for travel slide but not kaleidoscope pictures. Experiment 2 showed that learning names for the kaleidoscope pictures then resulted in a substantial (20%) ISI effect, not attributable solely to the added exposure to the pictures. Experiment 3 required names, color evaluations, or blank stares during list-memory presentations. Interviews established that the most effective memory strategy was chaining the names together, followed by repeating the most current name, and in turn followed by reliance upon only the sensory experience. All groups in Experiments 2 and 3, independent of ISI effects, showed U-shaped serial position functions. Rehearsal is shown to be nonessential and cannot be the general cause of the primary effect of the serial position function.

  2. Kiaman magnetic interval in the Western United States.

    PubMed

    McMahon, B E; Strangway, D W

    1967-02-24

    Late-Paleozoic red beds in the western United States indicate that Earth's magnetic field was reversed for a period of the order of 50 x 10(6) years. This finding agrees with similar results from igneous rocks in Australia, indicating, that the long period of reversal in the magnetic field was worldwide. The rocks on the two continents appear to be essentially equivalent in time, suggesting early magnetization of the red beds. The time spectrum of reversals is irregular in geologic time, but present evidence suggests reversals characterized by time scales of 10(4) or 10(5), 10(6), and 50 x 10(6) years. The 50 x 10(6) year period of steady reversed field is found in the late Paleozoic and is termed the Kiaman magnetic interval.

  3. The Elusive Universal Post-Mortem Interval Formula

    SciTech Connect

    Vass, Arpad Alexander

    2011-01-01

    The following manuscript details our initial attempt at developing universal post-mortem interval formulas describing human decomposition. These formulas are empirically derived from data collected over the last 20 years from the University of Tennessee's Anthropology Research Facility, in Knoxville, Tennessee, USA. Two formulas were developed (surface decomposition and burial decomposition) based on temperature, moisture, and the partial pressure of oxygen, as being three of the four primary drivers for human decomposition. It is hoped that worldwide application of these formulas to environments and situations not readily studied in Tennessee will result in interdisciplinary cooperation between scientists and law enforcement personnel that will allow for future refinements of these models leading to increased accuracy.

  4. The Whole Heliosphere Interval: Campaign Summaries and Early Results

    NASA Technical Reports Server (NTRS)

    Thompson, Barbara J.; Gibson, Sarah E.; Kozyra, Janet U.

    2008-01-01

    The Whole Heliosphere Interval (WHI) is an internationally coordinated observing and modeling effort to characterize the 3-dimensional interconnected solar-heliospheric-planetary system - a.k.a. the "heliophysical" system. The heart of the WHI campaign is the study of the interconnected 3-D heliophysical domain, from the interior of the Sun, to the Earth, outer planets, and into interstellar space. WHI observing campaigns began with the 3-0 solar structure from solar Carrington Rotation 2068, which ran from March 20 - April 16, 2008. Observations and models of the outer heliosphere and planetary impacts extended beyond those dates as necessary; for example, the solar wind transit time to outer planets can take months. WHI occurs during solar minimum, which optimizes our ability to characterize the 3-D heliosphere and trace the structure to the outer limits of the heliosphere. A summary of some of the key results from the WHI first workshop in August 2008 will be given.

  5. Concurrent certifications by intervals of timestamps in distributed database systems

    SciTech Connect

    Boksenbaum, C.; Cart, M.; Ferrie, J.; Pons, J.F.

    1987-04-01

    This paper introduces, an an optimistic concurrency control method, a new certification method by means of intervals of time-stamps, usable in a distributed database system. The main advantage of this method is that it allows a chronological commit order which differs from the serialization one (thus avoiding rejections or delays of transactions which occur in usual certification methods or in classical locking or timestamping ones). The use of the dependency graph permits both classifying this method among existing ones and proving it. The certification protocol is first presented under the hypothesis that transactions' certifications are processed in the same order on all the concerned sites; it is then extended to allow concurrent certifications of transactions.

  6. Comparing Simultaneous and Pointwise Confidence Intervals for Hydrological Processes.

    PubMed

    Francisco-Fernández, Mario; Quintela-del-Río, Alejandro

    2016-01-01

    Distribution function estimation of the random variable of river flow is an important problem in hydrology. This issue is directly related to quantile estimation, and consequently to return level prediction. The estimation process can be complemented with the construction of confidence intervals (CIs) to perform a probabilistic assessment of the different variables and/or estimated functions. In this work, several methods for constructing CIs using bootstrap techniques, and parametric and nonparametric procedures in the estimation process are studied and compared. In the case that the target is the joint estimation of a vector of values, some new corrections to obtain joint coverage probabilities closer to the corresponding nominal values are also presented. A comprehensive simulation study compares the different approaches, and the application of the different procedures to real data sets from four rivers in the United States and one in Spain complete the paper.

  7. [High-intensity interval training for young athletes].

    PubMed

    Engel, Florian Azad; Sperlich, Billy

    2014-06-01

    A computer-based literature research during July 2013 using the electronic databases PubMed, MEDLINE, SPORTDiscus and Web of Science was performed to assess the effect of the high intensity interval training (HIIT) on sport performance in healthy children and adolescents. Studies examining the effect of HIIT on aerobic and anaerobic performance pre and post to HIIT-Interventions in children and adolescents (9-18 years) were included. The results indicate increased aerobic and anaerobic performance following two or three HIIT sessions per week for a period of five to ten weeks, additional to normal training. Results regarding long term effects following HIIT have not been documented so far. In addition, due to the physiological characteris-tics during HIIT protocols improved fatigue resistance has been demonstrated in children as compared to adults, which may be interpreted as a prerequisite for the applicability of HIIT in children.

  8. A likelihood approach to calculating risk support intervals

    SciTech Connect

    Leal, S.M.; Ott, J. )

    1994-05-01

    Genetic risks are usually computed under the assumption that genetic parameters, such as the recombination fraction, are known without error. Uncertainty in the estimates of these parameters must translate into uncertainty regarding the risk. To allow for uncertainties in parameter values, one may employ Bayesian techniques or, in a maximum-likelihood framework, construct a support interval (SI) for the risk. Here the authors have implemented the latter approach. The SI for the risk is based on the SIs of parameters involved in the pedigree likelihood. As an empirical example, the SI for the risk was calculated for probands who are members of chronic spinal muscular atrophy kindreds. In order to evaluate the accuracy of a risk in genetic counseling situations, the authors advocate that, in addition to a point estimate, an SI for the risk should be calculated. 16 refs., 1 fig., 1 tab.

  9. Lipid Panel Reference Intervals for Amazon Parrots (Amazona species).

    PubMed

    Ravich, Michelle; Cray, Carolyn; Hess, Laurie; Arheart, Kristopher L

    2014-09-01

    The lipoprotein panel is a useful diagnostic tool that allows clinicians to evaluate blood lipoprotein fractions. It is a standard diagnostic test in human medicine but is poorly understood in avian medicine. Amazon parrots (Amazona species) are popular pets that frequently lead a sedentary lifestyle and are customarily fed high-fat diets. Similar to people with comparable diets and lifestyles, Amazon parrots are prone to obesity and atherosclerosis. In human medicine, these conditions are typically correlated with abnormalities in the lipoprotein panel. To establish reference intervals for the lipoprotein panel in Amazon parrots, plasma samples from 31 captive Amazon parrots were analyzed for concentrations of cholesterol, triglycerides, high-density lipoprotein (HDL), low-density lipoprotein (LDL), and very low-density lipoprotein (VLDL). The data were also grouped according to sex, diet, body condition score, and age. Aside from HDL levels, which were significantly different between male and female parrots, no intergroup differences were found for any of the lipoprotein fractions.

  10. The stabilization interval system of a tethered descent underwater vehicle

    NASA Astrophysics Data System (ADS)

    Gayvoronskiy, S. A.; Ezangina, T.; Khozhaev, I.; Efimov, S. V.

    2016-04-01

    To damp the vertical oscillations of a descent submersible caused by dusting the control system utilizing a shock-absorbing hoist located on the submersible was developed. A robust proportional-plus-integral action controller was included in the control loop to ensure acceptable dynamic properties of the system by interval variations of the module mass, the rope length, the equivalent value of stiffness of a spring linkage and the equivalent value of damping factor of the spring linkage. A parametric synthesis of the controller was carried out on the basis of the robust expansion of the coefficient method of the quality rating estimation. The system operability was confirmed by the results of the digital simulation parameters

  11. High-intensity aerobic interval exercise in chronic heart failure.

    PubMed

    Meyer, Philippe; Gayda, Mathieu; Juneau, Martin; Nigam, Anil

    2013-06-01

    Aerobic exercise training is strongly recommended in patients with heart failure (HF) and reduced left ventricular ejection fraction (LVEF) to improve symptoms and quality of life. Moderate-intensity aerobic continuous exercise (MICE) is the best established training modality in HF patients. For about a decade, however, another training modality, high-intensity aerobic interval exercise (HIIE), has aroused considerable interest in cardiac rehabilitation. Originally used by athletes, HIIE consists of repeated bouts of high-intensity exercise interspersed with recovery periods. The rationale for its use is to increase exercise time spent in high-intensity zones, thereby increasing the training stimulus. Several studies have demonstrated that HIIE is more effective than MICE, notably for improving exercise capacity in patients with HF. The aim of the present review is to describe the general principles of HIIE prescription, the acute physiological effects, the longer-term training effects, and finally the future perspectives of HIIE in patients with HF.

  12. Comparing Simultaneous and Pointwise Confidence Intervals for Hydrological Processes

    PubMed Central

    2016-01-01

    Distribution function estimation of the random variable of river flow is an important problem in hydrology. This issue is directly related to quantile estimation, and consequently to return level prediction. The estimation process can be complemented with the construction of confidence intervals (CIs) to perform a probabilistic assessment of the different variables and/or estimated functions. In this work, several methods for constructing CIs using bootstrap techniques, and parametric and nonparametric procedures in the estimation process are studied and compared. In the case that the target is the joint estimation of a vector of values, some new corrections to obtain joint coverage probabilities closer to the corresponding nominal values are also presented. A comprehensive simulation study compares the different approaches, and the application of the different procedures to real data sets from four rivers in the United States and one in Spain complete the paper. PMID:26828651

  13. Selective subcortical enhancement of musical intervals in musicians.

    PubMed

    Lee, Kyung Myun; Skoe, Erika; Kraus, Nina; Ashley, Richard

    2009-05-01

    By measuring the auditory brainstem response to two musical intervals, the major sixth (E3 and G2) and the minor seventh (E3 and F#2), we found that musicians have a more specialized sensory system for processing behaviorally relevant aspects of sound. Musicians had heightened responses to the harmonics of the upper tone (E), as well as certain combination tones (sum tones) generated by nonlinear processing in the auditory system. In music, the upper note is typically carried by the upper voice, and the enhancement of the upper tone likely reflects musicians' extensive experience attending to the upper voice. Neural phase locking to the temporal periodicity of the amplitude-modulated envelope, which underlies the perception of musical harmony, was also more precise in musicians than nonmusicians. Neural enhancements were strongly correlated with years of musical training, and our findings, therefore, underscore the role that long-term experience with music plays in shaping auditory sensory encoding.

  14. Precise time and time interval users, requirements and specifications

    NASA Technical Reports Server (NTRS)

    Bowser, J. R.

    1982-01-01

    The functional areas of application of Precise Time and Time Interval (PTTI) were considered and expanded. A comprehensive overview of the PTTI requirements and applications would provide an opportunity for individuals working in a specific functional area. Mutual problems, requirements, applications or successes shared by those in other functional areas were studied. Based upon the results of a two year study a compendium of PTTI requirements, applications and the means of meeting the requirements among Department of Defense components, other government agencies and major commercial users was compiled and is presented. It was found that the planning process for PTTI support for new acquisitions or new programs was less than a well defined, coordinated process. The processes are described in general terms and a generic model for requirements determination and subsequent coordination which may enhance the planning process and introduce cost benefits to the program is also presented.

  15. Estimation and confidence intervals for empirical mixing distributions

    USGS Publications Warehouse

    Link, W.A.; Sauer, J.R.

    1995-01-01

    Questions regarding collections of parameter estimates can frequently be expressed in terms of an empirical mixing distribution (EMD). This report discusses empirical Bayes estimation of an EMD, with emphasis on the construction of interval estimates. Estimation of the EMD is accomplished by substitution of estimates of prior parameters in the posterior mean of the EMD. This procedure is examined in a parametric model (the normal-normal mixture) and in a semi-parametric model. In both cases, the empirical Bayes bootstrap of Laird and Louis (1987, Journal of the American Statistical Association 82, 739-757) is used to assess the variability of the estimated EMD arising from the estimation of prior parameters. The proposed methods are applied to a meta-analysis of population trend estimates for groups of birds.

  16. Punished and unpunished responding in multiple variable-interval schedules.

    PubMed

    Tullis, C; Walters, G

    1968-03-01

    The performance of rats trained on multiple variable-interval schedules was examined before, during, and after punishment. The same linear function related relative response rates to relative density of reinforcement both in the presence and absence of punishment. Equal relative suppression was seen in both the high and low reinforcement density components. The intercept value of the function was zero. Each component of the schedule was programmed on a separate lever: thus during any component, there was an opportunity for responses on the nonoperative lever (errors). The proportions of these errors declined to a near-zero value during punishment and did not regain their prepunishment values after punishment was removed, suggesting that some discrimination learning occurred during punishment. Recovery of response rate during punishment was seen only where a greater-than-zero probability of reinforcement was associated with the response.

  17. Iridium abundance maxima in the Upper Cenomanian extinction interval

    NASA Astrophysics Data System (ADS)

    Orth, C. J.; Attrep, M., Jr.; Mao, X. Y.; Kauffman, E. G.; Diner, R.

    1988-04-01

    Two iridium abundance peaks, both 0.11 ppb (whole-rock basis) over a local background of 0.017 ppb, have been found in Middle Cretaceous marine rocks near Pueblo, Colorado. They occur just below the 92-million-year-old Cenomanian-Turonian (C-T) stage boundary. No other peaks were found in 45 meters of strata (about 2.5 million years of deposition) above and below the boundary interval. The broad lower peak straddles the first in a series of extinctions of benthic and nektonic macrobiota which comprise the C-T extinction event. The sharp upper peak occurs stratigraphically about 1.2 meters above the lower peak. The excess Ir might be from meteoroid impacts.

  18. Iridium abundance maxima in the Upper Cenomanian extinction interval

    NASA Technical Reports Server (NTRS)

    Orth, C. J.; Attrep, M., Jr.; Mao, X. Y.; Kauffman, E. G.; Diner, R.

    1988-01-01

    Two iridium abundance peaks, both 0.11 ppb (whole-rock basis) over a local background of 0.017 ppb, have been found in Middle Cretaceous marine rocks near Pueblo, Colorado. They occur just below the 92-million-year-old Cenomanian-Turonian (C-T) stage boundary. No other peaks were found in 45 meters of strata (about 2.5 million years of deposition) above and below the boundary interval. The broad lower peak straddles the first in a series of extinctions of benthic and nektonic macrobiota which comprise the C-T extinction event. The sharp upper peak occurs stratigraphically about 1.2 meters above the lower peak. The excess Ir might be from meteoroid impacts.

  19. Roll aftereffects: influence of tilt and inter-stimulus interval.

    PubMed

    Crane, Benjamin T

    2012-11-01

    A theme in sensory perception is that exposure to a stimulus causes perception of subsequent stimuli to be shifted in the opposite direction. Such phenomenon is known as aftereffect and has been extensively described in the visual system as well as recently described for the vestibular system during translation. It is known from aviation studies that after a maneuver in roll, pilots can experience a false perception of roll in the opposite direction. The magnitude and duration of this effect as well as the potential influence of the gravity vector have not previously been defined. In the current paper this roll aftereffect (RAE) is examined in response to whole-body roll about an earth-horizontal axis in eight healthy human subjects. The peak velocity of a 0.5-s-duration roll was varied based on previous responses to find the point where subjects perceived no motion. Without a preceding stimulus, the starting position (upright, 9° left, or 9° right) did not influence roll perception. The RAE was measured in a completely dark room using an adapting (first interval) stimulus consisting of 9° of roll over 1.5 s (peak velocity, 12°/s), delivered 0.5, 3, or 6 s prior to test (second interval) stimulus. A significant RAE was seen in all subjects. Half a second after the adapting stimulus, a test stimulus had to be on average 1.5 ± 0.4°/s in the opposite direction to be perceived as stationary. When the subject remained upright after the adapting stimulus, the RAE diminished with time, although it remained significantly larger at 3 and 6 s when the subject remained tilted after the adapting stimulus. These data demonstrate that roll perception can be influenced by small preceding stimuli and tilt causes a persistence of the RAE.

  20. Coronal inflows during the interval 1996-2014

    SciTech Connect

    Sheeley, N. R. Jr.; Wang, Y.-M.

    2014-12-10

    We extend our previous counts of coronal inflows from the 5 yr interval 1996-2001 to the 18 yr interval 1996-2014. By comparing stackplots of these counts with similar stackplots of the source-surface magnetic field and its longitudinal gradient, we find that the inflows occur in long-lived streams with counting rates in excess of 18 inflows per day at sector boundaries where the gradient exceeds 0.22 G rad{sup –1}. These streams are responsible for the high (86%) correlation between the inflow rate and the longitudinal field gradient. The overall inflow rate was several times larger in sunspot cycle 23 than it has been so far in cycle 24, reflecting the relatively weak source-surface fields during this cycle. By comparison, in cycles 21-22, the source-surface field and its gradient had bursts of great strength, as if large numbers of inflows occurred during those cycles. We find no obvious relation between inflows and coronal mass ejections (CMEs) on timescales of days to weeks, regardless of the speeds of the CMEs, and only a 60% correlation on timescales of months, provided the CMEs are fast (V > 600 km s{sup –1}). We conclude that most of the flux carried out by CMEs is returned to the Sun via field line reconnection well below the 2.0 R {sub ☉} inner limit of the LASCO field of view, and that the remainder accumulates in the outer corona for an eventual return at sector boundaries.

  1. Reference intervals: current status, recent developments and future considerations

    PubMed Central

    Ozarda, Yesim

    2016-01-01

    Reliable and accurate reference intervals (RIs) for laboratory analyses are an integral part of the process of correct interpretation of clinical laboratory test results. RIs given in laboratory reports have an important role in aiding the clinician in interpreting test results in reference to values for healthy populations. Since the 1980s, the International Federation of Clinical Chemistry (IFCC) has been proactive in establishing recommendations to clarify the true significance of the term ‘RIs, to select the appropriate reference population and statistically analyse the data. The C28-A3 guideline published by the Clinical and Laboratory Standards Institute (CLSI) and IFCC is still the most widely-used source of reference in this area. In recent years, protocols additional to the Guideline have been published by the IFCC, Committee on Reference Intervals and Decision Limits (C-RIDL), including all details of multicenter studies on RIs to meet the requirements in this area. Multicentric RIs studies are the most important development in the area of RIs. Recently, the C-RIDL has performed many multicentric studies to obtain common RIs. Confusion of RIs and clinical decision limits (CDLs) remains an issue and pediatric and geriatric age groups are a significant problem. For future studies of RIs, the genetic effect would seem to be the most challenging area.
The aim of the review is to present the current theory and practice of RIs, with special emphasis given to multicenter RIs studies, RIs studies for pediatric and geriatric age groups, clinical decision limits and partitioning by genetic effects on RIs. PMID:26981015

  2. Mapping of Estimations and Prediction Intervals Using Extreme Learning Machines

    NASA Astrophysics Data System (ADS)

    Leuenberger, Michael; Kanevski, Mikhail

    2015-04-01

    Due to the large amount and complexity of data available nowadays in environmental sciences, we face the need to apply more robust methodology allowing analyses and understanding of the phenomena under study. One particular but very important aspect of this understanding is the reliability of generated prediction models. From the data collection to the prediction map, several sources of error can occur and affect the final result. Theses sources are mainly identified as uncertainty in data (data noise), and uncertainty in the model. Their combination leads to the so-called prediction interval. Quantifying these two categories of uncertainty allows a finer understanding of phenomena under study and a better assessment of the prediction accuracy. The present research deals with a methodology combining a machine learning algorithm (ELM - Extreme Learning Machine) with a bootstrap-based procedure. Developed by G.-B. Huang et al. (2006), ELM is an artificial neural network following the structure of a multilayer perceptron (MLP) with one single hidden layer. Compared to classical MLP, ELM has the ability to learn faster without loss of accuracy, and need only one hyper-parameter to be fitted (that is the number of nodes in the hidden layer). The key steps of the proposed method are as following: sample from the original data a variety of subsets using bootstrapping; from these subsets, train and validate ELM models; and compute residuals. Then, the same procedure is performed a second time with only the squared training residuals. Finally, taking into account the two modeling levels allows developing the mean prediction map, the model uncertainty variance, and the data noise variance. The proposed approach is illustrated using geospatial data. References Efron B., and Tibshirani R. 1986, Bootstrap Methods for Standard Errors, Confidence Intervals, and Other Measures of Statistical accuracy, Statistical Science, vol. 1: 54-75. Huang G.-B., Zhu Q.-Y., and Siew C.-K. 2006

  3. Antioxidant status of interval-trained athletes in various sports.

    PubMed

    Dékány, M; Nemeskéri, V; Györe, I; Harbula, I; Malomsoki, J; Pucsok, J

    2006-02-01

    Muscular exercise results in an increased production of free radicals and other forms of reactive oxygen species (ROS). Further, developing evidence implicates cytotoxins as an underlying etiology of exercise-induced stimuli in muscle redox status, which could result in muscle fatigue and/or injury. Two major classes of endogenous protective mechanisms (enzymatic and nonenzymatic antioxidants) work together to reduce the harmful effects of oxidants in the cell. This study examined the effects of acute physical exercise on the enzymatic antioxidant systems of different athletes and comparison was made to the mechanism of action of three main antioxidant enzymes in the blood. Handball players (n = 6), water-polo players (n = 20), hockey players (n = 22), basketball players (n = 24), and a sedentary control group (n = 10 female and n = 9 male) served as the subjects of this study. The athletes were divided into two groups according to the observed changes of activity of superoxide dismutase enzyme. The antioxidant enzyme systems were characterized by catalase (CAT), glutathione-peroxidase (GPX), and superoxide-dismutase (SOD) and measured by spectrophotometry. An important finding in the present investigation is that when the activities of SOD increased, the activities of GPX and CAT increased also and this finding related to the physical status of interval-trained athletes. Positive correlation between SOD and GPX activities was observed (r = 0.38 females, r = 0.56 males; p < 0.05). We have observed that the changes in the primary antioxidant enzyme systems of athletes are sport specific, and different from control subjects. Presumably, with interval-trained athletes, hydrogen-peroxide is significantly eliminated by glutathione-peroxidase. From these results it can be concluded that the blood redox status should be taken into consideration when establishing a fitness level for individual athletes.

  4. A comparison of several methods for the confidence intervals of negative binomial proportions

    NASA Astrophysics Data System (ADS)

    Thong, Alfred Lim Sheng; Shan, Fam Pei

    2015-12-01

    This study focuses on the comparison of the performances of several approaches in constructing confidence interval of negative binomial proportions (single negative binomial proportion and the difference between two negative binomial proportions). After that, the strengths and weaknesses of the approaches in constructing confidence interval of negative binomial proportions are figured out. Performances of the approaches will be accessed by comparing their coverage probabilities and average lengths of confidence intervals. For the comparison of the performances of the approaches in single negative binomial proportion, Wald confidence interval (WCI-I), Agresti confidence interval (ACI-I), Wilson's Score confidence interval (WSCI-I) and Jeffrey confidence interval (JCI-I) are used. WSCI-I is the better approach for single negative binomial proportion in term of the average length of confidence intervals and average coverage probability. While for the comparison of the performances of the approaches in the difference between two negative binomial proportions, Wald confidence interval (WCI-II), Agresti confidence interval (ACI-II), Newcombe's Score confidence interval (NSCI-II), Jeffrey confidence interval (JCI-II) and Yule confidence interval (YCI-II) are used. Under different situations, a better approach has been discussed and recommended. There will be different approach that performs better for the coverage probability.

  5. ON-LINE TOOLS FOR PROPER VERTICAL POSITIONING OF VERTICAL SAMPLING INTERVALS DURING SITE ASSESSMENT

    EPA Science Inventory

    This presentation presents on-line tools for proper vertical positioning of vertical sampling intervals during site assessment. Proper vertical sample interval selection is critical for generate data on the vertical distribution of contamination. Without vertical delineation, th...

  6. Bootstrap Prediction Intervals in Non-Parametric Regression with Applications to Anomaly Detection

    NASA Technical Reports Server (NTRS)

    Kumar, Sricharan; Srivistava, Ashok N.

    2012-01-01

    Prediction intervals provide a measure of the probable interval in which the outputs of a regression model can be expected to occur. Subsequently, these prediction intervals can be used to determine if the observed output is anomalous or not, conditioned on the input. In this paper, a procedure for determining prediction intervals for outputs of nonparametric regression models using bootstrap methods is proposed. Bootstrap methods allow for a non-parametric approach to computing prediction intervals with no specific assumptions about the sampling distribution of the noise or the data. The asymptotic fidelity of the proposed prediction intervals is theoretically proved. Subsequently, the validity of the bootstrap based prediction intervals is illustrated via simulations. Finally, the bootstrap prediction intervals are applied to the problem of anomaly detection on aviation data.

  7. Simultaneous confidence intervals for a steady-state leaky aquifer groundwater flow model

    USGS Publications Warehouse

    Christensen, S.; Cooley, R.L.

    1996-01-01

    Using the optimization method of Vecchia & Cooley (1987), nonlinear Scheffe??-type confidence intervals were calculated tor the parameters and the simulated heads of a steady-state groundwater flow model covering 450 km2 of a leaky aquifer. The nonlinear confidence intervals are compared to corresponding linear intervals. As suggested by the significant nonlinearity of the regression model, linear confidence intervals are often not accurate. The commonly made assumption that widths of linear confidence intervals always underestimate the actual (nonlinear widths was not correct for the head intervals. Results show that nonlinear effects can cause the nonlinear intervals to be offset from, and either larger or smaller than, the linear approximations. Prior information on some transmissivities helps reduce and stabilize the confidence intervals, with the most notable effects occurring for the parameters on which there is prior information and for head values in parameter zones for which there is prior information on the parameters.

  8. Effects of wait-time and intertrial interval durations on learning by children with multiple handicaps.

    PubMed Central

    Valcante, G; Roberson, W; Reid, W R; Wolking, W D

    1989-01-01

    We investigated the influence of teacher wait-time and intertrial interval durations on the performance of 4 multiply handicapped students during instruction in 10 skills. Four experimental conditions were evaluated: long wait-time and long intertrial interval, long wait-time and short intertrial interval, short wait-time and long intertrial interval, and short wait-time and short intertrial interval. Instructors attempted to keep short intervals as close as possible to 1 s and long intervals as close as possible to 10 s for both variables. Results showed that student performance was superior under the long wait-time conditions irrespective of the length of the intertrial interval. PMID:2523372

  9. Interval and composite interval mapping of somatic cell score, yield, and components of milk in dairy cattle.

    PubMed

    Rodriguez-Zas, S L; Southey, B R; Heyen, D W; Lewin, H A

    2002-11-01

    Single-marker, interval-mapping (IM) and composite interval mapping (CIM) were used to detect quantitative trait loci (QTL) controlling milk, fat and protein yields, and somatic cell score (SCS). A granddaughter design was used to combine molecular genetic information with predicted transmitting abilities (PTA) and estimated daughter yield deviations (DYD) from eight Dairy Bull DNA Repository Holstein families. Models that included and excluded weights accounting for the uncertainty of the response variable were evaluated in each trait, family and phenotype (DYD and PTA) combination. The genotypic information consisted of 174 microsatellite markers along 29 Bos taurus autosomes. The average number of informative markers per autosome was three and the number of informative sons per family and marker varied between 21 and 173. Within-family results from the least squares single-marker analyses were used in expectation-maximization likelihood IM and CIM implemented with QTL Cartographer. Different CIM model specifications, offering complementary control on the background QTL outside the interval under study, were evaluated. Permutation techniques were used to calculate the genome-wide threshold test statistic values based on 1,000 samples. Results from the DYD and PTA analyses were highly consistent across traits and families. The minor differences in the estimates from the models that accounted for or ignored the uncertainty of the DYD (variance) and PTA (inverse of reliability) may be associated to the elevated and consistent precision of the DYD and PTA among sons. The CIM model best supported by the data had 10 markers controlling for background effects. On autosome (BTA) three, a QTL at 32 cM influencing protein yield was located in family five and a QTL at 74 cM for fat yield was located in family eight. Two map positions associated with SCS were detected on BTA 21, one at 33 cM in family one and the other at 84 cM in family three. A QTL for protein yield was

  10. Altered relationship between R-R interval and R-R interval variability in endurance athletes with overtraining syndrome.

    PubMed

    Kiviniemi, A M; Tulppo, M P; Hautala, A J; Vanninen, E; Uusitalo, A L T

    2014-04-01

    Autonomic dysfunction decreases within-subject correlation between R-R interval length (RRi) and vagally mediated RRi variability in cardiac disease. We tested the hypothesis that overtraining syndrome (OTS) may also weaken this relationship. Nine OTS and 10 control endurance athletes underwent 24-h electrocardiogram monitoring, which was repeated in eight OTS and nine control athletes after 6 months, when two OTS athletes still had symptoms of OTS. The power of high-frequency (HF) oscillations of RRi was analyzed in 5-min epochs over the whole recording. Quadratic regression was performed between 5-min values of RRi and log-transformed (ln) HF to obtain R(2) for each recording. The relationship between RRi and HFln was higher in the OTS athletes than controls [R(2): 0.87 (90% confidence interval, CI: 0.84-0.89) vs 0.78 (90% CI: 0.72-0.84); P = 0.034; effect size = 1.22]. Large decrease in R(2) was observed in six recovered OTS athletes after 6 months follow-up [ΔR(2): -0.12 (90% CI: -0.25-0.01); P = 0.11; effect size = 1.44] with no changes in the controls. Mean values of RRi and its variability did not differ between the groups. The within-subject correlation between RRi and vagally mediated RRi variability was stronger in endurance athletes with OTS compared with controls. The present findings may improve the detection of OTS and recovery from OTS in endurance athletes.

  11. Comparison of Cardiorespiratory and Metabolic Responses in Kettlebell High-Intensity Interval Training Versus Sprint Interval Cycling.

    PubMed

    Williams, Brian M; Kraemer, Robert R

    2015-12-01

    The purpose of this study was to determine the effectiveness of a novel exercise protocol we developed for kettlebell high-intensity interval training (KB-HIIT) by comparing the cardiorespiratory and metabolic responses to a standard sprint interval cycling (SIC) exercise protocol. Eight men volunteered for the study and completed 2 preliminary sessions, followed by two 12-minute sessions of KB-HIIT and SIC in a counterbalanced fashion. In the KB-HITT session, 3 circuits of 4 exercises were performed using a Tabata regimen. In the SIC session, three 30-second sprints were performed, with 4 minutes of recovery in between the first 2 sprints and 2.5 minutes of recovery after the last sprint. A within-subjects' design over multiple time points was used to compare oxygen consumption (V[Combining Dot Above]O2), respiratory exchange ratio (RER), tidal volume (TV), breathing frequency (f), minute ventilation (VE), caloric expenditure rate (kcal·min), and heart rate (HR) between the exercise protocols. Additionally, total caloric expenditure was compared. A significant group effect, time effect, and group × time interaction were found for V[Combining Dot Above]O2, RER, and TV, with V[Combining Dot Above]O2 being higher and TV and RER being lower in the KB-HIIT compared with the SIC. Only a significant time effect and group × time interaction were found for f, VE, kcal·min, and HR. Additionally, total caloric expenditure was found to be significantly higher during the KB-HIIT. The results of this study suggest that KB-HIIT may be more attractive and sustainable than SIC and can be effective in stimulating cardiorespiratory and metabolic responses that could improve health and aerobic performance. PMID:26360962

  12. Introduction to Sample Size Choice for Confidence Intervals Based on "t" Statistics

    ERIC Educational Resources Information Center

    Liu, Xiaofeng Steven; Loudermilk, Brandon; Simpson, Thomas

    2014-01-01

    Sample size can be chosen to achieve a specified width in a confidence interval. The probability of obtaining a narrow width given that the confidence interval includes the population parameter is defined as the power of the confidence interval, a concept unfamiliar to many practitioners. This article shows how to utilize the Statistical Analysis…

  13. Adjusted Wald Confidence Interval for a Difference of Binomial Proportions Based on Paired Data

    ERIC Educational Resources Information Center

    Bonett, Douglas G.; Price, Robert M.

    2012-01-01

    Adjusted Wald intervals for binomial proportions in one-sample and two-sample designs have been shown to perform about as well as the best available methods. The adjusted Wald intervals are easy to compute and have been incorporated into introductory statistics courses. An adjusted Wald interval for paired binomial proportions is proposed here and…

  14. Interresponse Time Structures in Variable-Ratio and Variable-Interval Schedules

    ERIC Educational Resources Information Center

    Bowers, Matthew T.; Hill, Jade; Palya, William L.

    2008-01-01

    The interresponse-time structures of pigeon key pecking were examined under variable-ratio, variable-interval, and variable-interval plus linear feedback schedules. Whereas the variable-ratio and variable-interval plus linear feedback schedules generally resulted in a distinct group of short interresponse times and a broad distribution of longer…

  15. Reference Intervals of Common Clinical Chemistry Analytes for Adults in Hong Kong

    PubMed Central

    Lo, YC

    2012-01-01

    Background Defining reference intervals is a major challenge because of the difficulty in recruiting volunteers to participate and testing samples from a significant number of healthy reference individuals. Historical literature citation intervals are often suboptimal because they’re be based on obsolete methods and/or only a small number of poorly defined reference samples. Methods Blood donors in Hong Kong gave permission for additional blood to be collected for reference interval testing. The samples were tested for twenty-five routine analytes on the Abbott ARCHITECT clinical chemistry system. Results were analyzed using the Rhoads EP evaluator software program, which is based on the CLSI/IFCC C28-A guideline, and defines the reference interval as the 95% central range. Results Method specific reference intervals were established for twenty-five common clinical chemistry analytes for a Chinese ethnic population. The intervals were defined for each gender separately and for genders combined. Gender specific or combined gender intervals were adapted as appropriate for each analyte. Conclusion A large number of healthy, apparently normal blood donors from a local ethnic population were tested to provide current reference intervals for a new clinical chemistry system. Intervals were determined following an accepted international guideline. Laboratories using the same or similar methodologies may adapt these intervals if deemed validated and deemed suitable for their patient population. Laboratories using different methodologies may be able to successfully adapt the intervals for their facilities using the reference interval transference technique based on a method comparison study.

  16. 49 CFR 192.939 - What are the required reassessment intervals?

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ..., Pressure Test or Direct Assessment 10 years (*) 15 years (*) 20 years. (**) Confirmatory Direct Assessment... conducted by year 7 in a 10-year interval and years 7 and 14 of a 15-year interval. (**) A low stress... method is seven years. If an operator establishes a reassessment interval that is greater than...

  17. 49 CFR 192.939 - What are the required reassessment intervals?

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ..., Pressure Test or Direct Assessment 10 years (*) 15 years (*) 20 years.(**) Confirmatory Direct Assessment 7... year 7 in a 10-year interval and years 7 and 14 of a 15-year interval. (**) A low stress reassessment... method is seven years. If an operator establishes a reassessment interval that is greater than...

  18. 49 CFR 192.939 - What are the required reassessment intervals?

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ..., Pressure Test or Direct Assessment 10 years (*) 15 years (*) 20 years.(**) Confirmatory Direct Assessment 7... year 7 in a 10-year interval and years 7 and 14 of a 15-year interval. (**) A low stress reassessment... method is seven years. If an operator establishes a reassessment interval that is greater than...

  19. 49 CFR 192.939 - What are the required reassessment intervals?

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ..., Pressure Test or Direct Assessment 10 years (*) 15 years (*) 20 years. (**) Confirmatory Direct Assessment... conducted by year 7 in a 10-year interval and years 7 and 14 of a 15-year interval. (**) A low stress... method is seven years. If an operator establishes a reassessment interval that is greater than...

  20. 49 CFR 192.939 - What are the required reassessment intervals?

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ..., Pressure Test or Direct Assessment 10 years (*) 15 years (*) 20 years.(**) Confirmatory Direct Assessment 7... year 7 in a 10-year interval and years 7 and 14 of a 15-year interval. (**) A low stress reassessment... method is seven years. If an operator establishes a reassessment interval that is greater than...

  1. The effect of filled and empty intervals on clock and memory processes in pigeons.

    PubMed

    Price, Elizabeth; Santi, Angelo

    2014-06-01

    According to the mixed memory model (Penney, Gibbon, & Meck, Journal of Experimental Psychology: Human Perception and Performance, 26, 1770-1787, 2000), different clock rates for stimuli with different nontemporal properties must be stored within a single reference memory distribution in order to detect a difference between the clock rates of the different signals. In Experiment 1, pigeons were trained in a between-subjects design to discriminate empty intervals (bound by two 1-s visual markers) and filled intervals (a continuous visual signal). The intervals were signaled by different visual stimuli, and they required responses to different sets of comparison stimuli. Empty intervals were judged as being longer than filled intervals. The difference between the point of subjective equality (PSE) for the empty intervals and the PSE for the filled intervals increased proportionally as the magnitudes of the anchor duration pairs were increased from 2 and 8 s to 4 and 16 s. In Experiment 2, the pigeons were trained to discriminate intervals signaled by the absence of houselight illumination (Group Empty) or the presence of houselight illumination (Group Filled). The psychophysical timing functions for these intervals were identical to each other. The results of Experiment 1 indicate that memory mixing is not necessary for detecting a timing difference between empty and filled intervals in pigeons. The results of Experiment 2 suggest that the nature of the stimuli that signal the empty and filled intervals impacts how pigeons judge the durations of empty and filled intervals.

  2. A study to determine the usefulness of interval analysis in solving problems in celestial mechanics

    NASA Technical Reports Server (NTRS)

    Walling, D.

    1974-01-01

    This investigation was undertaken to determine the usefulness of interval analysis to numerical integration and matrix inversion techniques and to combine these results to determine the value of interval analysis in bounding computational errors in the two-body problem. Conclusions were that interval analysis may be worthwhile in certain small scale isolated problems, but its usefulness in any large scale problem is doubtful.

  3. Calibration Interval Adjustment of a Measuring Instrument in Industries During Long-term Use

    NASA Astrophysics Data System (ADS)

    Natalinova, N.; Ilina, N.; Frantcuzskaia, E.

    2016-06-01

    Calibration interval adjustment of measuring instruments is one of the urgent tasks in industries. The article represents the calibration interval calculation of the potentiometer PCB-4P according to the verifications for the 4 year period of the Metrological Department in the aviation plant. The calibration interval is shown to be increased according to the calculation of its reliability and stability of metrological characteristics.

  4. The Effects of Interval Duration on Temporal Tracking and Alternation Learning

    ERIC Educational Resources Information Center

    Ludvig, Elliot A.; Staddon, John E. R.

    2005-01-01

    On cyclic-interval reinforcement schedules, animals typically show a postreinforcement pause that is a function of the immediately preceding time interval ("temporal tracking"). Animals, however, do not track single-alternation schedules--when two different intervals are presented in strict alternation on successive trials. In this experiment,…

  5. Oceanographic Changes through the Early Triassic Crisis Interval

    NASA Astrophysics Data System (ADS)

    Algeo, T. J.

    2013-12-01

    Recent studies of diverse paleoceanographic proxies have provided the basis for reconstructing in some detail oceanographic changes during the end-Permian mass extinction and through the ~5-million-year-long Early Triassic crisis interval. Conodont δ18O records have demonstrated strong warming, to tropical sea-surface temperatures as high as 40oC, during the Griesbachian to Dienerian substages1-2. The crisis interval also was associated with major perturbations in the marine carbon and sulfur cycles. Three episodes of strong warming coincided with decreases in marine carbonate δ13C and marine sulfate δ34S 3, as well as increases in Δδ13Cvert4 and enhanced subaerial weathering fluxes5-6. Lower δ13Ccarb and δ34Ssulf values are indicative of more limited burial of reduced C and S in organic carbon and pyrite, consistent with declines in marine productivity and bacterial sulfate reduction3. Increased Δδ13Cvert is indicative of intensified stratification of the oceanic water column4, and increased subaerial weathering fluxes probably reflect higher soil reaction rates and possibly an intensified hydrologic cycle5-6. Collectively, these patterns are indicative of the globally integrated response of marine and terrestrial regimes to episodic perturbations in the form of extreme warming events1-2,7. These warming events may have been triggered by major volcanic eruptions8, as suggested by recent studies of volcanic ash layers9-10 and rare earth elements11 in South China P-Tr boundary sections. The ~2-million-year-long Early Triassic interval of extreme sea-surface temperatures came to an abrupt end around the Smithian-Spathian boundary1-2. Cooling coincided with a sharp decline in Δδ13Cvert due to stronger vertical overturning circulation4 and a major positive excursion in δ13Ccarb due to increased marine productivity related to greater mixing of nutrients into the ocean-surface layer12. The late Spathian was characterized by a final, weaker episode of sea

  6. Hourly Wind Speed Interval Prediction in Arid Regions

    NASA Astrophysics Data System (ADS)

    Chaouch, M.; Ouarda, T.

    2013-12-01

    context, probabilistic forecasts might be more relevant than point forecasts for the planner to build scenarios In this paper, we are interested in estimating predictive intervals of the hourly wind speed measures in few cities in United Arab emirates (UAE). More precisely, given a wind speed time series, our target is to forecast the wind speed at any specific hour during the day and provide in addition an interval with the coverage probability 0interval we need to estimate the lower band (resp. upper band) which corresponds to the (1-p)/2-th (resp. (1+p)/2-th) conditional quantile. In this paper, a kernel-smoothed estimator of the conditional quantiles is introduced. The proposed non-parametric approach has many advantages since it is flexible because it does not need a specification of the model to work with (such as normal distribution or a linear relation). Here, we use a covariable that is correlated to the wind speed. In practice, many possible choices of the covariate are available. In fact, in addition to its historical data, the wind speed is highly correlated to temperature, humidity and wind direction. In this paper a comparison, in terms of Mean Absolute Prediction Errors and Interquartile Range, between those choices will be provided to show which covariates are more suitable to forecast wind speed.

  7. Wind Information Uplink to Aircraft Performing Interval Management Operations

    NASA Technical Reports Server (NTRS)

    Ahmad, Nashat N.; Barmore, Bryan E.; Swieringa, Kurt A.

    2016-01-01

    Interval Management (IM) is an ADS-B-enabled suite of applications that use ground and flight deck capabilities and procedures designed to support the relative spacing of aircraft (Barmore et al., 2004, Murdoch et al. 2009, Barmore 2009, Swieringa et al. 2011; Weitz et al. 2012). Relative spacing refers to managing the position of one aircraft to a time or distance relative to another aircraft, as opposed to a static reference point such as a point over the ground or clock time. This results in improved inter-aircraft spacing precision and is expected to allow aircraft to be spaced closer to the applicable separation standard than current operations. Consequently, if the reduced spacing is used in scheduling, IM can reduce the time interval between the first and last aircraft in an overall arrival flow, resulting in increased throughput. Because IM relies on speed changes to achieve precise spacing, it can reduce costly, low-altitude, vectoring, which increases both efficiency and throughput in capacity-constrained airspace without negatively impacting controller workload and task complexity. This is expected to increase overall system efficiency. The Flight Deck Interval Management (FIM) equipment provides speeds to the flight crew that will deliver them to the achieve-by point at the controller-specified time, i.e., assigned spacing goal, after the target aircraft crosses the achieve-by point (Figure 1.1). Since the IM and target aircraft may not be on the same arrival procedure, the FIM equipment predicts the estimated times of arrival (ETA) for both the IM and target aircraft to the achieve-by point. This involves generating an approximate four-dimensional trajectory for each aircraft. The accuracy of the wind data used to generate those trajectories is critical to the success of the IM operation. There are two main forms of uncertainty in the wind information used by the FIM equipment. The first is the accuracy of the forecast modeling done by the weather

  8. Fuzzy interval Finite Element/Statistical Energy Analysis for mid-frequency analysis of built-up systems with mixed fuzzy and interval parameters

    NASA Astrophysics Data System (ADS)

    Yin, Hui; Yu, Dejie; Yin, Shengwen; Xia, Baizhan

    2016-10-01

    This paper introduces mixed fuzzy and interval parametric uncertainties into the FE components of the hybrid Finite Element/Statistical Energy Analysis (FE/SEA) model for mid-frequency analysis of built-up systems, thus an uncertain ensemble combining non-parametric with mixed fuzzy and interval parametric uncertainties comes into being. A fuzzy interval Finite Element/Statistical Energy Analysis (FIFE/SEA) framework is proposed to obtain the uncertain responses of built-up systems, which are described as intervals with fuzzy bounds, termed as fuzzy-bounded intervals (FBIs) in this paper. Based on the level-cut technique, a first-order fuzzy interval perturbation FE/SEA (FFIPFE/SEA) and a second-order fuzzy interval perturbation FE/SEA method (SFIPFE/SEA) are developed to handle the mixed parametric uncertainties efficiently. FFIPFE/SEA approximates the response functions by the first-order Taylor series, while SFIPFE/SEA improves the accuracy by considering the second-order items of Taylor series, in which all the mixed second-order items are neglected. To further improve the accuracy, a Chebyshev fuzzy interval method (CFIM) is proposed, in which the Chebyshev polynomials is used to approximate the response functions. The FBIs are eventually reconstructed by assembling the extrema solutions at all cut levels. Numerical results on two built-up systems verify the effectiveness of the proposed methods.

  9. Reproducibility and reliability of fetal cardiac time intervals using magnetocardiography.

    PubMed

    van Leeuwen, P; Lange, S; Klein, A; Geue, D; Zhang, Y; Krause, H J; Grönemeyer, D

    2004-04-01

    We investigated several factors which may affect the accuracy of fetal cardiac time intervals (CTI) determined in magnetocardiographic (MCG) recordings: observer differences, the number of available recording sites and the type of sensor used in acquisition. In 253 fetal MCG recordings, acquired using different biomagnetometer devices between the 15th and 42nd weeks of gestation, P-wave, QRS complex and T-wave onsets and ends were identified in signal averaged data sets independently by different observers. Using a defined procedure for setting signal events, interobserver reliability was high. Increasing the number of registration sites led to more accurate identification of the events. The differences in wave morphology between magnetometer and gradiometer configurations led to deviations in timing whereas the differences between low and high temperature devices seemed to be primarily due to noise. Signal-to-noise ratio played an important overall role in the accurate determination of CTI and changes in signal amplitude associated with fetal maturation may largely explain the effects of gestational age on reproducibility. As fetal CTI may be of value in the identification of pathologies such as intrauterine growth retardation or fetal cardiac hypertrophy, their reliable estimation will be enhanced by strategies which take these factors into account.

  10. Central tendency effects in time interval reproduction in autism

    PubMed Central

    Karaminis, Themelis; Cicchini, Guido Marco; Neil, Louise; Cappagli, Giulia; Aagten-Murphy, David; Burr, David; Pellicano, Elizabeth

    2016-01-01

    Central tendency, the tendency of judgements of quantities (lengths, durations etc.) to gravitate towards their mean, is one of the most robust perceptual effects. A Bayesian account has recently suggested that central tendency reflects the integration of noisy sensory estimates with prior knowledge representations of a mean stimulus, serving to improve performance. The process is flexible, so prior knowledge is weighted more heavily when sensory estimates are imprecise, requiring more integration to reduce noise. In this study we measure central tendency in autism to evaluate a recent theoretical hypothesis suggesting that autistic perception relies less on prior knowledge representations than typical perception. If true, autistic children should show reduced central tendency than theoretically predicted from their temporal resolution. We tested autistic and age- and ability-matched typical children in two child-friendly tasks: (1) a time interval reproduction task, measuring central tendency in the temporal domain; and (2) a time discrimination task, assessing temporal resolution. Central tendency reduced with age in typical development, while temporal resolution improved. Autistic children performed far worse in temporal discrimination than the matched controls. Computational simulations suggested that central tendency was much less in autistic children than predicted by theoretical modelling, given their poor temporal resolution. PMID:27349722

  11. Inelastic supply: An economic approach to simple interval schedules.

    PubMed

    Dougan, J D

    1992-11-01

    Economic theory predicts an inverse relationship between the quantity of a commodity supplied to the marketplace and the equilibrium market price of that commodity. This prediction was tested in three experiments. Pigeons responded on simple variable-interval schedules, and quantity of reinforcement supplied was varied in a different way in each experiment. In Experiment 1, quantity supplied was varied by manipulating reinforcement rate while keeping session length constant. In Experiment 2, quantity supplied was varied by manipulating reinforcement rate while keeping reinforcers per session constant. In Experiment 3, quantity supplied was varied by manipulating reinforcer magnitude while keeping number of reinforcers constant. As predicted by economic theory, the obtained behavioral cost (responses per reinforcer) increased as supply decreased. The results could not be explained by simple artifacts such as satiation and time available to respond. In addition, the function relating response rate to reinforcement rate was bitonic in 7 of 9 animals in Experiments 1 and 2, which supports economic and regulatory theories over more traditional reinforcement theories.

  12. Precise time and time interval applications to electric power systems

    NASA Technical Reports Server (NTRS)

    Wilson, Robert E.

    1992-01-01

    There are many applications of precise time and time interval (frequency) in operating modern electric power systems. Many generators and customer loads are operated in parallel. The reliable transfer of electrical power to the consumer partly depends on measuring power system frequency consistently in many locations. The internal oscillators in the widely dispersed frequency measuring units must be syntonized. Elaborate protection and control systems guard the high voltage equipment from short and open circuits. For the highest reliability of electric service, engineers need to study all control system operations. Precise timekeeping networks aid in the analysis of power system operations by synchronizing the clocks on recording instruments. Utility engineers want to reproduce events that caused loss of service to customers. Precise timekeeping networks can synchronize protective relay test-sets. For dependable electrical service, all generators and large motors must remain close to speed synchronism. The stable response of a power system to perturbations is critical to continuity of electrical service. Research shows that measurement of the power system state vector can aid in the monitoring and control of system stability. If power system operators know that a lightning storm is approaching a critical transmission line or transformer, they can modify operating strategies. Knowledge of the location of a short circuit fault can speed the re-energizing of a transmission line. One fault location technique requires clocks synchronized to one microsecond. Current research seeks to find out if one microsecond timekeeping can aid and improve power system control and operation.

  13. Measurement bias in activation-recovery intervals from unipolar electrograms

    PubMed Central

    Hanson, Ben; Taggart, Peter

    2014-01-01

    The activation-recovery interval (ARI) calculated from unipolar electrograms is regularly used as a convenient surrogate measure of local cardiac action potential durations (APD). This method enables important research bridging between computational studies and in vitro and in vivo human studies. The Wyatt method is well established as a theoretically sound method for calculating ARIs; however, some studies have observed that it is prone to a bias error in measurement when applied to positive T waves. This article demonstrates that recent theoretical and computational studies supporting the use of the Wyatt method are likely to have underestimated the extent of this bias in many practical experimental recording scenarios. This work addresses these situations and explains the measurement bias by adapting existing theoretical expressions of the electrogram to represent practical experimental recording configurations. A new analytic expression for the electrogram's local component is derived, which identifies the source of measurement bias for positive T waves. A computer implementation of the new analytic model confirms our hypothesis that the bias is systematically dependent on the electrode configuration. These results provide an aid to electrogram interpretation in general, and this work's outcomes are used to make recommendations on how to minimize measurement error. PMID:25398981

  14. Strict and random alternation in concurrent variable-interval schedules.

    PubMed Central

    Elliffe, Douglas; Davison, Michael

    2003-01-01

    Six pigeons responded on pairs of concurrent variable-interval schedules with, in different parts, four different arrangements of alternation between schedules. Following a single switching-key response, alternation was either strict or random, and the alternative presented after a switch (the postswitch alternative) was either signaled by the location of the switching key or unsignaled. Generalized-matching analyses showed little difference in behavior among the different alternation arrangements, except the usual finding of lower sensitivity of response allocation than time allocation was eliminated by arranging random alternation. Patterns of interchangeover times were similar for all arrangements except signaled random alternation. Differences in behavior preceding the different postswitch alternatives were found in the signaled random alternation procedure. Preference was biased towards the color of the signaled postswitch alternative and showed increased sensitivity when the postswitch alternative was to be the one with the higher reinforcer rate. Interchangeover times were substantially shorter when the postswitch alternative was signaled to be different from the current alternative than when it was signaled to be the same. However, when separate reinforcer ratios were calculated for the different postswitch alternatives, those effects were eliminated or greatly reduced. We suggest that, although behavior is indeed influenced by the postswitch alternative, the mechanism is indirect. That is, the distributions of reinforcers between alternatives obtained before each postswitch alternative differ when those alternatives are signaled, and those distributions are discriminated, but the same relations between choice and relative reinforcement hold irrespective of which postswitch alternative is signaled. PMID:12696742

  15. Analysis of neural spike trains with interspike interval reconstruction.

    PubMed

    Suzuki, H; Aihara, K; Murakami, J; Shimozawa, T

    2000-04-01

    As a method for the analysis of neural spike trains, we examine fundamental characteristics of interspike interval (ISI) reconstruction theoretically with a leaky-integrator neuron model and experimentally with cricket wind receptor cells. Both the input to the leaky integrator and the stimulus to the wind receptor cells are the time series generated from the Rossler system. By numerical analysis of the leaky integrator, it is shown that, even if ISI reconstruction is possible, sometimes the entire structure of the Rössler attractor may not be reconstructed with ISI reconstruction. For analysis of the in vivo physiological responses of cricket wind receptor cells, we apply ISI reconstruction, nonlinear prediction and the surrogate data method to the experimental data. As a result of the analysis, it is found that there is a significant deterministic structure in the spike trains. By this analysis of physiological data, it is also shown that, even if ISI reconstruction is possible, the entire attractor may not be reconstructed. PMID:10804062

  16. A Comparative Study of Interval Management Control Law Capabilities

    NASA Technical Reports Server (NTRS)

    Barmore, Bryan E.; Smith, Colin L.; Palmer, Susan O.; Abbott, Terence S.

    2012-01-01

    This paper presents a new tool designed to allow for rapid development and testing of different control algorithms for airborne spacing. This tool, Interval Management Modeling and Spacing Tool (IM MAST), is a fast-time, low-fidelity tool created to model the approach of aircraft to a runway, with a focus on their interactions with each other. Errors can be induced between pairs of aircraft by varying initial positions, winds, speed profiles, and altitude profiles. Results to-date show that only a few of the algorithms tested had poor behavior in the arrival and approach environment. The majority of the algorithms showed only minimal variation in performance under the test conditions. Trajectory-based algorithms showed high susceptibility to wind forecast errors, while performing marginally better than the other algorithms under other conditions. Trajectory-based algorithms have a sizable advantage, however, of being able to perform relative spacing operations between aircraft on different arrival routes and flight profiles without employing ghosting. methods. This comes at the higher cost of substantially increased complexity, however. Additionally, it was shown that earlier initiation of relative spacing operations provided more time for corrections to be made without any significant problems in the spacing operation itself. Initiating spacing farther out, however, would require more of the aircraft to begin spacing before they merge onto a common route.

  17. Quantization of spacetime based on a spacetime interval operator

    NASA Astrophysics Data System (ADS)

    Chiang, Hsu-Wen; Hu, Yao-Chieh; Chen, Pisin

    2016-04-01

    Motivated by both concepts of Adler's recent work on utilizing Clifford algebra as the linear line element d s =⟨γμ⟩ d Xμ and the fermionization of the cylindrical worldsheet Polyakov action, we introduce a new type of spacetime quantization that is fully covariant. The theory is based on the reinterpretation of Adler's linear line element as d s =γμ⟨λ γμ⟩ , where λ is the characteristic length of the theory. We name this new operator the "spacetime interval operator" and argue that it can be regarded as a natural extension to the one-forms in the U (s u (2 )) noncommutative geometry. By treating Fourier momentum as the particle momentum, the generalized uncertainty principle of the U (s u (2 )) noncommutative geometry, as an approximation to the generalized uncertainty principle of our theory, is derived and is shown to have a lowest order correction term of the order p2 similar to that of Snyder's. The holography nature of the theory is demonstrated and the predicted fuzziness of the geodesic is shown to be much smaller than conceivable astrophysical bounds.

  18. A model of return intervals between earthquake events

    NASA Astrophysics Data System (ADS)

    Zhou, Yu; Chechkin, Aleksei; Sokolov, Igor M.; Kantz, Holger

    2016-06-01

    Application of the diffusion entropy analysis and the standard deviation analysis to the time sequence of the southern California earthquake events from 1976 to 2002 uncovered scaling behavior typical for anomalous diffusion. However, the origin of such behavior is still under debate. Some studies attribute the scaling behavior to the correlations in the return intervals, or waiting times, between aftershocks or mainshocks. To elucidate a nature of the scaling, we applied specific reshulffling techniques to eliminate correlations between different types of events and then examined how it affects the scaling behavior. We demonstrate that the origin of the scaling behavior observed is the interplay between mainshock waiting time distribution and the structure of clusters of aftershocks, but not correlations in waiting times between the mainshocks and aftershocks themselves. Our findings are corroborated by numerical simulations of a simple model showing a very similar behavior. The mainshocks are modeled by a renewal process with a power-law waiting time distribution between events, and aftershocks follow a nonhomogeneous Poisson process with the rate governed by Omori's law.

  19. Interval Mapping of Quantitative Trait Loci Employing Correlated Trait Complexes

    PubMed Central

    Korol, A. B.; Ronin, Y. I.; Kirzhner, V. M.

    1995-01-01

    An approach to increase the resolution power of interval mapping of quantitative trait (QT) loci is proposed, based on analysis of correlated trait complexes. For a given set of QTs, the broad sense heritability attributed to a QT locus (QTL) (say, A/ a) is an increasing function of the number of traits. Thus, for some traits x and y, H(xy)(2) (A/ a) >/= H(x)(2) (A/ a). The last inequality holds even if y does not depend on A/ a at all, but x and y are correlated within the groups AA, Aa and aa due to nongenetic factors and segregation of genes from other chromosomes. A simple relationship connects H(2) (both in single trait and two-trait analysis) with the expected LOD value, ELOD = -1/2N log(1 - H(2)). Thus, situations could exist that from the inequality H(xy)(2) (A/ a) >/= H(x)(2) (A/ a) a higher resolution is provided by the two-trait analysis as compared to the single-trait analysis, in spite of the increased number of parameters. Employing LOD-score procedure to simulated backcross data, we showed that the resolution power of the QTL mapping model can be elevated if correlation between QTs is taken into account. The method allows us to test numerous biologically important hypotheses concerning manifold effects of genomic segments on the defined trait complex (means, variances and correlations). PMID:7672584

  20. Probing interval timing with scalp-recorded electroencephalography (EEG).

    PubMed

    Ng, Kwun Kei; Penney, Trevor B

    2014-01-01

    Humans, and other animals, are able to easily learn the durations of events and the temporal relationships among them in spite of the absence of a dedicated sensory organ for time. This chapter summarizes the investigation of timing and time perception using scalp-recorded electroencephalography (EEG), a non-invasive technique that measures brain electrical potentials on a millisecond time scale. Over the past several decades, much has been learned about interval timing through the examination of the characteristic features of averaged EEG signals (i.e., event-related potentials, ERPs) elicited in timing paradigms. For example, the mismatch negativity (MMN) and omission potential (OP) have been used to study implicit and explicit timing, respectively, the P300 has been used to investigate temporal memory updating, and the contingent negative variation (CNV) has been used as an index of temporal decision making. In sum, EEG measures provide biomarkers of temporal processing that allow researchers to probe the cognitive and neural substrates underlying time perception.

  1. Behavior Detection using Confidence Intervals of Hidden Markov Models

    SciTech Connect

    Griffin, Christopher H

    2009-01-01

    Markov models are commonly used to analyze real-world problems. Their combination of discrete states and stochastic transitions is suited to applications with deterministic and stochastic components. Hidden Markov Models (HMMs) are a class of Markov model commonly used in pattern recognition. Currently, HMMs recognize patterns using a maximum likelihood approach. One major drawback with this approach is that data observations are mapped to HMMs without considering the number of data samples available. Another problem is that this approach is only useful for choosing between HMMs. It does not provide a criteria for determining whether or not a given HMM adequately matches the data stream. In this work, we recognize complex behaviors using HMMs and confidence intervals. The certainty of a data match increases with the number of data samples considered. Receiver Operating Characteristic curves are used to find the optimal threshold for either accepting or rejecting a HMM description. We present one example using a family of HMM's to show the utility of the proposed approach. A second example using models extracted from a database of consumer purchases provides additional evidence that this approach can perform better than existing techniques.

  2. Anxiolytic-like effects of leptin on fixed interval responding.

    PubMed

    Tyree, Susan M; Munn, Robert G K; McNaughton, Neil

    2016-09-01

    Leptin has been shown to affect energy homeostasis, learning and memory, and some models of anxiolytic action. However, leptin has produced inconsistent results in previous non-operant behavioural tests of anxiety. Here, we test the anxiolytic potential of leptin in an operant paradigm that has produced positive results across all classes of anxiolytic so far tested. Rats were tested in the Fixed Interval 60 Seconds (FI60) task following administration of 0/0.5/1.0mg/kg (i.p.) leptin or an active anxiolytic control of 5mg/kg (i.p.) chlordiazepoxide (CDP). By the end of the 14days of testing in the FI60 task, 0.5mg/kg leptin released suppressed responding in a manner similar to CDP, and 1.0mg/kg leptin produced a relative depression in responding, a similar outcome pattern to previously tested 5HT-agonist anxiolytics. This suggests that leptin behaves similarly to established serotonergic anxiolytics such as buspirone and fluoxetine; with the delay in development of effect during testing, and the inverted-U dose-response curve explaining the inconsistent behaviour of leptin in behavioural tests of anxiety, as this type of pattern is common to serotonergic anxiolytics. PMID:27180106

  3. Linkage disequilibrium interval mapping of quantitative trait loci

    PubMed Central

    Boitard, Simon; Abdallah, Jihad; de Rochambeau, Hubert; Cierco-Ayrolles, Christine; Mangin, Brigitte

    2006-01-01

    Background For many years gene mapping studies have been performed through linkage analyses based on pedigree data. Recently, linkage disequilibrium methods based on unrelated individuals have been advocated as powerful tools to refine estimates of gene location. Many strategies have been proposed to deal with simply inherited disease traits. However, locating quantitative trait loci is statistically more challenging and considerable research is needed to provide robust and computationally efficient methods. Results Under a three-locus Wright-Fisher model, we derived approximate expressions for the expected haplotype frequencies in a population. We considered haplotypes comprising one trait locus and two flanking markers. Using these theoretical expressions, we built a likelihood-maximization method, called HAPim, for estimating the location of a quantitative trait locus. For each postulated position, the method only requires information from the two flanking markers. Over a wide range of simulation scenarios it was found to be more accurate than a two-marker composite likelihood method. It also performed as well as identity by descent methods, whilst being valuable in a wider range of populations. Conclusion Our method makes efficient use of marker information, and can be valuable for fine mapping purposes. Its performance is increased if multiallelic markers are available. Several improvements can be developed to account for more complex evolution scenarios or provide robust confidence intervals for the location estimates. PMID:16542433

  4. Eyelid response topography in differential interstimulus interval conditioning.

    PubMed

    Kadlac, J A; Grant, D A

    1977-05-01

    The problem of conditioned eyelid discrimination was investigated with a differential interstimulus interval (ISI) conditioning procedure. In two groups, conditioned stimulus (CS) lights presented in the left or right visual fields signaled ISIs of 800 or 1,200 msec before delivery of an airpuff unconditioned stimulus. Two additional groups received one or the other ISI with both CSs. Somewhat unexpectedly, none of the response-frequency or topography measures showed evidence of conditioned discrimination in the differential ISI groups. Instead, the latencies and puff-attenuating topographies of responses were much more appropriate to the ISI given on the preceding trial, n--1, than to the ISI cued on trial n. Neither the absence of conditioned discrimination nor the presence of ISI sequential effects was related to subjects' reported awareness of the CS-ISI contingencies, suggesting that the overriding process was a relatively "automatic" shaping and reshaping of responses in accord with recent ISI experience. These results are discussed in terms of the complex stimulus- and response-processing requirements of the task. Across all four groups there was some evidence of a relative excitatory response bias to CSs presented in the right visual field, and it was found that voluntary-form responders (but not conditioned-form responders) initially gave more alpha responses to the right-field CS than to the left-field CS. These results were examined for possible hemispheric processing implications. PMID:870612

  5. Extending Sensor Calibration Intervals in Nuclear Power Plants

    SciTech Connect

    Coble, Jamie B.; Meyer, Ryan M.; Ramuhalli, Pradeep; Bond, Leonard J.; Shumaker, Brent; Hashemian, Hash

    2012-11-15

    Currently in the USA, sensor recalibration is required at every refueling outage, and it has emerged as a critical path item for shortening outage duration. International application of calibration monitoring, such as at the Sizewell B plant in UK, has shown that sensors may operate for eight years, or longer, within calibration tolerances. Online monitoring can be employed to identify those sensors which require calibration, allowing for calibration of only those sensors which need it. The US NRC accepted the general concept of online monitoring for sensor calibration monitoring in 2000, but no plants have been granted the necessary license amendment to apply it. This project addresses key issues in advanced recalibration methodologies and provides the science base to enable adoption of best practices for applying online monitoring, resulting in a public domain standardized methodology for sensor calibration interval extension. Research to develop this methodology will focus on three key areas: (1) quantification of uncertainty in modeling techniques used for calibration monitoring, with a particular focus on non-redundant sensor models; (2) accurate determination of acceptance criteria and quantification of the effect of acceptance criteria variability on system performance; and (3) the use of virtual sensor estimates to replace identified faulty sensors to extend operation to the next convenient maintenance opportunity.

  6. Bias-corrected confidence intervals for the concentration parameter in a dilution assay.

    PubMed

    Wang, J; Basu, S

    1999-03-01

    Interval estimates of the concentration of target entities from a serial dilution assay are usually based on the maximum likelihood estimator. The distribution of the maximum likelihood estimator is skewed to the right and is positively biased. This bias results in interval estimates that either provide inadequate coverage relative to the nominal level or yield excessively long intervals. Confidence intervals based on both log transformation and bias reduction are proposed and are shown through simulations to provide appropriate coverage with shorter widths than the commonly used intervals in a variety of designs. An application to feline AIDS research, which motivated this work, is also presented.

  7. Successive intervals analysis of preference measures in a health status index.

    PubMed Central

    Blischke, W R; Bush, J W; Kaplan, R M

    1975-01-01

    The method of successive intervals, a procedure for obtaining equal intervals from category data, is applied to social preference data for a health status index. Several innovations are employed, including an approximate analysis of variance test for determining whether the intervals are of equal width, a regression model for estimating the width of the end intervals in finite scales, and a transformation to equalize interval widths and estimate item locations on the new scale. A computer program has been developed to process large data sets with a larger number of categories than previous programs. PMID:1219005

  8. Reconstruction of phylogenetic trees of prokaryotes using maximal common intervals.

    PubMed

    Heydari, Mahdi; Marashi, Sayed-Amir; Tusserkani, Ruzbeh; Sadeghi, Mehdi

    2014-10-01

    One of the fundamental problems in bioinformatics is phylogenetic tree reconstruction, which can be used for classifying living organisms into different taxonomic clades. The classical approach to this problem is based on a marker such as 16S ribosomal RNA. Since evolutionary events like genomic rearrangements are not included in reconstructions of phylogenetic trees based on single genes, much effort has been made to find other characteristics for phylogenetic reconstruction in recent years. With the increasing availability of completely sequenced genomes, gene order can be considered as a new solution for this problem. In the present work, we applied maximal common intervals (MCIs) in two or more genomes to infer their distance and to reconstruct their evolutionary relationship. Additionally, measures based on uncommon segments (UCS's), i.e., those genomic segments which are not detected as part of any of the MCIs, are also used for phylogenetic tree reconstruction. We applied these two types of measures for reconstructing the phylogenetic tree of 63 prokaryotes with known COG (clusters of orthologous groups) families. Similarity between the MCI-based (resp. UCS-based) reconstructed phylogenetic trees and the phylogenetic tree obtained from NCBI taxonomy browser is as high as 93.1% (resp. 94.9%). We show that in the case of this diverse dataset of prokaryotes, tree reconstruction based on MCI and UCS outperforms most of the currently available methods based on gene orders, including breakpoint distance and DCJ. We additionally tested our new measures on a dataset of 13 closely-related bacteria from the genus Prochlorococcus. In this case, distances like rearrangement distance, breakpoint distance and DCJ proved to be useful, while our new measures are still appropriate for phylogenetic reconstruction.

  9. Geodetic strain of Greece in the interval 1892-1992

    NASA Astrophysics Data System (ADS)

    Davies, R.; England, P.; Parsons, B.; Billiris, H.; Paradissis, D.; Veis, G.

    1997-11-01

    A first-order triangulation of Greece was carried out in the 1890s. Reoccupation, using Global Positioning System receivers, of 46 of the 93 original markers yielded estimates of the deformation of the region over the intervening interval. Broad regions have similar geodetic strain over the 100-year time span. Strain north of the Gulf of Korinthos is predominantly north-south extension, though with a significant east-west component. The central Peloponnisos is relatively stable, whereas the gulfs of the southern Peloponnisos are all characterized by uniaxial east-west extension. The seismic expression of strain for the entire region, calculated from the seismic moment tensors of earthquakes of MS≥5.8 during the past 100 years, accounts for only 20-50% of the geodetically determined strain. At a scale of 50-100 km, the fraction of the strain that is expressed seismically varies much more than this range. In particular, whereas seismic strain in the eastern Gulf of Korinthos over the past 100 years is commensurate with the geodetic strain, there is rapid extension across the western Gulf of Korinthos (˜0.3 μstrain yr-1), with negligible seismic strain for the 100 year period prior to 1992. The Egion earthquake of June 1995 in the western Gulf of Korinthos released only a small proportion (≤20%) of the elastic strain that had accumulated in that region. The observed distribution of displacements can be explained by the relative rotation of two plates with a broad accommodation zone between them, but it is equally consistent with the deformation that would be expected of a sheet of fluid moving toward a low-pressure boundary at the Hellenic Trench. A simple calculation implies that if the region does behave as a fluid, then its effective viscosity is ˜1022-1023 Pa s. Such viscosities are consistent with the deformation of a lithosphere obeying a rheological law similar to that obtained for olivine in the laboratory.

  10. A Multicenter Reference Intervals Study for Specific Proteins in China

    PubMed Central

    Qin, Xuzhen; Tang, Guodong; Qiu, Ling; Li, Peng Chang; Xia, Liangyu; Chen, Ming; Tao, Zhihua; Li, Shijun; Liu, Min; Wang, Liang; Gao, Shang; Yu, Songlin; Cheng, Xinqi; Han, Jianhua; Hou, Li’an; Kawano, Reo; Ichihara, Kiyoshi

    2015-01-01

    Abstract A multicenter study conducted in healthy population of 6 cities from the 4 corners and central China for 7 serum-specific proteins to identify the sources of variation and establish the reference intervals on 2 automation platforms. A total of 3148 subjects aged 19 to 64 years old were enrolled in this study to ensure at least 120 participants in each 10-year age group and each city. The majority of samples were transported to central laboratory and measured on both Beckman AU5800 and Immage 800 analytical systems. Three-level nested ANOVA, multiple regression analysis, and the scatter plot were used to explore the variations from sex, age, region, BMI, cigarette smoking, and so on. The latent abnormal value exclusion (LAVE) method was applied at the time of computing RIs as a method for secondary exclusion. Regionality was not observed in any of the immunoassay in China. Variations for sex were significant for IgM among the immune analytes. For CRP and hsCRP results with turbidimetry method (Beckman Coulter AU5800) were lower than the nephelometry method (Beckman Immage). The LAVE method did not affect the RIs computed for the majority of analytes except C4, CRP, and hsCRP. In the scatter plot at the age of 45 years old C3, C4, and IgM reached an inflection point, accordingly RIs were separated by the age group. With the lack of regional differences and the well-standardized status of test results, the RIs of C3, IgG, IgA, IgM derived from this nationwide study can be used for the entire Chinese population. C4, CRP, and hsCRP were affected by different platforms and gender was a significant source of variation for IgM, so they had separated RIs. PMID:26656356

  11. Remote Sensing Tertiary Education Meets High Intensity Interval Training

    NASA Astrophysics Data System (ADS)

    Joyce, K. E.; White, B.

    2015-04-01

    Enduring a traditional lecture is the tertiary education equivalent of a long, slow, jog. There are certainly some educational benefits if the student is able to maintain concentration, but they are just as likely to get caught napping and fall off the back end of the treadmill. Alternatively, a pre-choreographed interactive workshop style class requires students to continually engage with the materials. Appropriately timed breaks or intervals allow students to recover briefly before being increasingly challenged throughout the class. Using an introductory remote sensing class at Charles Darwin University, this case study presents a transition from the traditional stand and deliver style lecture to an active student-led learning experience. The class is taught at undergraduate and postgraduate levels, with both on-campus as well as online distance learning students. Based on the concept that active engagement in learning materials promotes 'stickiness' of subject matter, the remote sensing class was re-designed to encourage an active style of learning. Critically, class content was reviewed to identify the key learning outcomes for the students. This resulted in a necessary sacrifice of topic range for depth of understanding. Graduates of the class reported high levels of enthusiasm for the materials, and the style in which the class was taught. This paper details a number of techniques that were used to engage students in active and problem based learning throughout the semester. It suggests a number of freely available tools that academics in remote sensing and related fields can readily incorporate into their teaching portfolios. Moreover, it shows how simple it can be to provide a far more enjoyable and effective learning experience for students than the one dimensional lecture.

  12. A Multicenter Reference Intervals Study for Specific Proteins in China.

    PubMed

    Qin, Xuzhen; Tang, Guodong; Qiu, Ling; Li, Peng Chang; Xia, Liangyu; Chen, Ming; Tao, Zhihua; Li, Shijun; Liu, Min; Wang, Liang; Gao, Shang; Yu, Songlin; Cheng, Xinqi; Han, Jianhua; Hou, Li'an; Kawano, Reo; Ichihara, Kiyoshi

    2015-12-01

    A multicenter study conducted in healthy population of 6 cities from the 4 corners and central China for 7 serum-specific proteins to identify the sources of variation and establish the reference intervals on 2 automation platforms.A total of 3148 subjects aged 19 to 64 years old were enrolled in this study to ensure at least 120 participants in each 10-year age group and each city. The majority of samples were transported to central laboratory and measured on both Beckman AU5800 and Immage 800 analytical systems. Three-level nested ANOVA, multiple regression analysis, and the scatter plot were used to explore the variations from sex, age, region, BMI, cigarette smoking, and so on. The latent abnormal value exclusion (LAVE) method was applied at the time of computing RIs as a method for secondary exclusion.Regionality was not observed in any of the immunoassay in China. Variations for sex were significant for IgM among the immune analytes. For CRP and hsCRP results with turbidimetry method (Beckman Coulter AU5800) were lower than the nephelometry method (Beckman Immage). The LAVE method did not affect the RIs computed for the majority of analytes except C4, CRP, and hsCRP. In the scatter plot at the age of 45 years old C3, C4, and IgM reached an inflection point, accordingly RIs were separated by the age group.With the lack of regional differences and the well-standardized status of test results, the RIs of C3, IgG, IgA, IgM derived from this nationwide study can be used for the entire Chinese population. C4, CRP, and hsCRP were affected by different platforms and gender was a significant source of variation for IgM, so they had separated RIs. PMID:26656356

  13. Flight Deck Interval Management Avionics: Eye-Tracking Analysis

    NASA Technical Reports Server (NTRS)

    Latorella, Kara; Harden, John W.

    2015-01-01

    Interval Management (IM) is one NexGen method for achieving airspace efficiencies. In order to initiate IM procedures, Air Traffic Control provides an IM clearance to the IM aircraft's pilots that indicates an intended spacing from another aircraft (the target to follow - or TTF) and the point at which this should be achieved. Pilots enter the clearance in the flight deck IM (FIM) system; and once the TTF's Automatic Dependent Surveillance-Broadcast signal is available, the FIM algorithm generates target speeds to meet that IM goal. This study examined four Avionics Conditions (defined by the instrumentation and location presenting FIM information) and three Notification Methods (defined by the visual and aural alerts that notified pilots to IM-related events). Current commercial pilots flew descents into Dallas/Fort-Worth in a high-fidelity commercial flight deck simulation environment with realistic traffic and communications. All 12 crews experienced each Avionics Condition, where order was counterbalanced over crews. Each crew used only one of the three Notification Methods. This paper presents results from eye tracking data collected from both pilots, including: normalized number of samples falling within FIM displays, normalized heads-up time, noticing time, dwell time on first FIM display look after a new speed, a workload-related metric, and a measure comparing the scan paths of pilot flying and pilot monitoring; and discusses these in the context of other objective (vertical and speed profile deviations, response time to dial in commanded speeds, out-of-speed-conformance and reminder indications) and subjective measures (workload, situation awareness, usability, and operational acceptability).

  14. Transits of planets with small intervals in circumbinary systems

    SciTech Connect

    Liu, Hui-Gen; Wang, Ying; Zhang, Hui; Zhou, Ji-Lin

    2014-08-01

    Transit times around single stars can be described well by a linear ephemeris. However, transit times in circumbinary systems are influenced both by the gravitational perturbations and the orbital phase variations of the central binary star. Adopting a coplanar analog of Kepler-16 as an example, we find that circumbinary planets can transit the same star more than once during a single planetary orbit, a phenomenon we call 'tight transits.' In certain geometric architecture, the projected orbital velocity of the planet and the secondary star can approach zero and change sign, resulting in very long transits and/or 2-3 transits during a single binary orbit. Whether tight transits are possible for a particular system depends primarily on the binary mass ratio and the orbital architecture of both the binary and the planet. We derive a time-dependent criterion to judge when tight transits are possible for any circumbinary system. These results are verified with full dynamical integrations that also reveal other tight transit characteristics, i.e., the transit durations and the intervals between tight transits. For the seven currently known circumbinary systems, we estimate these critical parameters both analytically and numerically. Due to the mutual inclination between the planet and the binary, tight transits can only occur across the less massive star B in Kepler-16, -34, -35, and -47 (for both planets). The long-term average frequency of tight transits (compared to typical transits) for Kepler-16, -34, and -35 are estimated to be several percent. Using full numerical integrations, the next tight transit for each system is predicted and the soonest example appears to be Kepler-47b and -47c, which are likely to have tight transits before 2025. These unique and valuable events often deserve special observational scrutiny.

  15. Two Efficient Twin ELM Methods With Prediction Interval.

    PubMed

    Ning, Kefeng; Liu, Min; Dong, Mingyu; Wu, Cheng; Wu, ZhanSong

    2015-09-01

    In the operational optimization and scheduling problems of actual industrial processes, such as iron and steel, and microelectronics, the operational indices and process parameters usually need to be predicted. However, for some input and output variables of these prediction models, there may exist a lot of uncertainties coming from themselves, the measurement error, the rough representation, and so on. In such cases, constructing a prediction interval (PI) for the output of the corresponding prediction model is very necessary. In this paper, two twin extreme learning machine (TELM) models for constructing PIs are proposed. First, we propose a regularized asymmetric least squares extreme learning machine (RALS-ELM) method, in which different weights of its squared error loss function are set according to whether the error of the model output is positive or negative in order that the above error can be differentiated in the parameter learning process, and Tikhonov regularization is introduced to reduce overfitting. Then, we propose an asymmetric Bayesian extreme learning machine (AB-ELM) method based on the Bayesian framework with the asymmetric Gaussian distribution (AB-ELM), in which the weights of its likelihood function are determined as the same method in RALS-ELM, and the type II maximum likelihood algorithm is derived to learn the parameters of AB-ELM. Based on RALS-ELM and AB-ELM, we use a pair of weights following the reciprocal relationship to obtain two nonparallel regressors, including a lower-bound regressor and an upper-bound regressor, respectively, which can be used for calculating the PIs. Finally, some discussions are given, about how to adjust the weights adaptively to meet the desired PI, how to use the proposed TELMs for nonlinear quantile regression, and so on. Results of numerical comparison on data from one synthetic regression problem, three University of California Irvine benchmark regression problems, and two actual industrial regression

  16. Food webs: ordering species according to body size yields high degree of intervality.

    PubMed

    Zook, Alexander E; Eklof, Anna; Jacob, Ute; Allesina, Stefano

    2011-02-21

    Food webs, the networks describing "who eats whom" in an ecosystem, are nearly interval, i.e. there is a way to order the species so that almost all the resources of each consumer are adjacent in the ordering. This feature has important consequences, as it means that the structure of food webs can be described using a single (or few) species' traits. Moreover, exploiting the quasi-intervality found in empirical webs can help build better models for food web structure. Here we investigate which species trait is a good proxy for ordering the species to produce quasi-interval orderings. We find that body size produces a significant degree of intervality in almost all food webs analyzed, although it does not match the maximum intervality for the networks. There is also a great variability between webs. Other orderings based on trophic levels produce a lower level of intervality. Finally, we extend the concept of intervality from predator-centered (in which resources are in intervals) to prey-centered (in which consumers are in intervals). In this case as well we find that body size yields a significant, but not maximal, level of intervality. These results show that body size is an important, although not perfect, trait that shapes species interactions in food webs. This has important implications for the formulation of simple models used to construct realistic representations of food webs.

  17. Coseismic thermal pressurization can prolong recurrence intervals of earthquake cycle

    NASA Astrophysics Data System (ADS)

    Mitsui, Y.; Hirahara, K.

    2008-12-01

    recurrence intervals of the earthquake cycle because of the higher static stress drop compared to the case without TP.

  18. Running sprint interval training induces fat loss in women.

    PubMed

    Hazell, Tom J; Hamilton, Craig D; Olver, T Dylan; Lemon, Peter W R

    2014-08-01

    Data on whether sprint interval training (SIT) (repeated supermaximal intensity, short-duration exercise) affects body composition are limited, and the data that are available suggest that men respond more favourably than do women. Moreover, most SIT data involve cycling exercise, and running may differ because of the larger muscle mass involved. Further, running is a more universal exercise type. This study assessed whether running SIT can alter body composition (air displacement plethysmography), waist circumference, maximal oxygen consumption, peak running speed, and (or) the blood lipid profile. Fifteen recreationally active women (age, 22.9 ± 3.6 years; height, 163.9 ± 5.1 cm; mass, 60.8 ± 5.2 kg) completed 6 weeks of running SIT (4 to 6, 30-s "all-out" sprints on a self-propelled treadmill separated by 4 min of rest performed 3 times per week). Training decreased body fat mass by 8.0% (15.1 ± 3.6 to 13.9 ± 3.4 kg, P = 0.002) and waist circumference by 3.5% (80.1 ± 4.2 to 77.3 ± 4.4 cm, P = 0.048), whereas it increased fat-free mass by 1.3% (45.7 ± 3.5 to 46.3 ± 2.9 kg, P = 0.05), maximal oxygen consumption by 8.7% (46 ± 5 to 50 ± 6 mL/(kg·min), P = 0.004), and peak running speed by 4.8% (16.6 ± 1.7 to 17.4 ± 1.4 km/h, P = 0.026). There were no differences in food intake assessed by 3-day food records (P > 0.329) or in blood lipids (P > 0.595), except for a slight decrease in high-density lipoprotein concentration (1.34 ± 0.28 to 1.24 ± 0.24 mmol/L, P = 0.034). Running SIT is a time-efficient strategy for decreasing body fat while increasing aerobic capacity, peak running speed, and fat-free mass in healthy young women.

  19. Whys and Hows of the Parameterized Interval Analyses: A Guide for the Perplexed

    NASA Astrophysics Data System (ADS)

    Elishakoff, I.

    2013-10-01

    Novel elements of the parameterized interval analysis developed in [1, 2] are emphasized in this response, to Professor E.D. Popova, or possibly to others who may be perplexed by the parameterized interval analysis. It is also shown that the overwhelming majority of comments by Popova [3] are based on a misreading of our paper [1]. Partial responsibility for this misreading can be attributed to the fact that explanations provided in [1] were laconic. These could have been more extensive in view of the novelty of our approach [1, 2]. It is our duty, therefore, to reiterate, in this response, the whys and hows of parameterization of intervals, introduced in [1] to incorporate the possibly available information on dependencies between various intervals describing the problem at hand. This possibility appears to have been discarded by the standard interval analysis, which may, as a result, lead to overdesign, leading to the possible divorce of engineers from the otherwise beautiful interval analysis.

  20. Temporal search as a function of the variability of interfood intervals.

    PubMed

    Church, R M; Lacourse, D M; Crystal, J D

    1998-07-01

    We attempted to determine whether timing theories developed primarily to explain performance in fixed-interval reinforcement schedules are also applicable to variable intervals. Groups of rats were trained in lever boxes on peak procedures with a 30-, 45-, or 60-s interval, or a 30- to 60-s uniform distribution (Experiment 1); a 60-s fixed and 1- to 121-s uniform distribution between and within animals (Experiment 2); and a procedure in which the interval between food and next available food gradually changed from a fixed 60 s to a uniform distribution between 0 and 120 s (Experiment 3). In uniform interval schedules rats made lever responses at particular times since food, as measured by the distribution of food-food intervals, the distribution of postreinforcement pauses, and the mean response rate as a function of time since food. Qualitative features of this performance are described by a multiple-oscillator connectionist theory of timing.

  1. [Heart rate variability study based on a novel RdR RR Intervals Scatter Plot].

    PubMed

    Lu, Hongwei; Lu, Xiuyun; Wang, Chunfang; Hua, Youyuan; Tian, Jiajia; Liu, Shihai

    2014-08-01

    On the basis of Poincare scatter plot and first order difference scatter plot, a novel heart rate variability (HRV) analysis method based on scatter plots of RR intervals and first order difference of RR intervals (namely, RdR) was proposed. The abscissa of the RdR scatter plot, the x-axis, is RR intervals and the ordinate, y-axis, is the difference between successive RR intervals. The RdR scatter plot includes the information of RR intervals and the difference between successive RR intervals, which captures more HRV information. By RdR scatter plot analysis of some records of MIT-BIH arrhythmias database, we found that the scatter plot of uncoupled premature ventricular contraction (PVC), coupled ventricular bigeminy and ventricular trigeminy PVC had specific graphic characteristics. The RdR scatter plot method has higher detecting performance than the Poincare scatter plot method, and simpler and more intuitive than the first order difference method.

  2. Department of Defense Precise Time and Time Interval program improvement plan

    NASA Technical Reports Server (NTRS)

    Bowser, J. R.

    1981-01-01

    The United States Naval Observatory is responsible for ensuring uniformity in precise time and time interval operations including measurements, the establishment of overall DOD requirements for time and time interval, and the accomplishment of objectives requiring precise time and time interval with minimum cost. An overview of the objectives, the approach to the problem, the schedule, and a status report, including significant findings relative to organizational relationships, current directives, principal PTTI users, and future requirements as currently identified by the users are presented.

  3. Biomechanical Comparison of the Interval Throwing Progression and Baseball Pitching

    PubMed Central

    Slenker, Nicholas; Limpisvasti, Orr; Mohr, Karen; ElAttrache, Neal S.

    2014-01-01

    Objectives: The interval throwing progression is a hallmark of the rehabilitation program designed for baseball pitchers or position players returning from shoulder or elbow injury. It typically begins with flat-ground throws at a short distance and progressively increases to 180 feet or more. For pitchers, this phase is then followed by throwing off the mound, progressing from partial-effort to full-effort pitches. Theoretically, the progression of throwing phases allows an injured athlete to gradually recover his flexibility, arm strength, and mechanics while moving from less stressful activities to more stressful activities. While this throwing program has been a part of baseball rehabilitation and conditioning for decades, little is known about the biomechanical stresses generated during flat-ground throwing or variable effort pitching off the mound. Methods: Twenty-nine healthy, college baseball pitchers were analyzed using a quantitative motion analysis system. The participants threw from flat ground at distances of 60-ft, 90-ft, 120-ft, and 180-ft, being instructed to throw “hard, on a horizontal line”. The pitchers then threw fastballs from a mound at 3 different efforts: 60% effort, 80% effort, and full-effort. Biomechanical parameters of position, velocity, and kinetic values were recorded. Mean values were calculated for humeral internal rotation torque (HIRT) and elbow valgus load (EVL) for each throw type. This data was then used to compare shoulder and elbow stresses between the various throws. The differences among mean values were analyzed with a repeated-measures analysis of variance (ANOVA). Post hoc paired t tests were performed when the ANOVA revealed a significant difference. Results: Statistically significant differences exist across all mound intensities (60%, 80%, and 100% effort) for nHIRT (p=0.03) and nEVL (p=0.04), as both parameters increased with percentage throwing effort. No statistically significant differences were found across

  4. Hydrologic studies in wells open through large intervals. Annual report, 1992

    SciTech Connect

    Not Available

    1992-12-31

    This report describes and summarizes activities, data, and preliminary data interpretation from the INEL Oversight Program R&D-1 project titled ``Hydrologic Studies In Wells Open Through Large Intervals.`` The project is designed to use a straddle-packer system to isolate, hydraulically test, and sample specific intervals of monitoring wells that are open (uncased, unscreened) over large intervals of the Snake River Plain aquifer. The objectives of the project are to determine and compare vertical variations in water quality and aquifer properties that have previously only been determined in an integrated fashion over the entire thickness of the open interval of the observation wells.

  5. Brain Bases of Working Memory for Time Intervals in Rhythmic Sequences.

    PubMed

    Teki, Sundeep; Griffiths, Timothy D

    2016-01-01

    Perception of auditory time intervals is critical for accurate comprehension of natural sounds like speech and music. However, the neural substrates and mechanisms underlying the representation of time intervals in working memory are poorly understood. In this study, we investigate the brain bases of working memory for time intervals in rhythmic sequences using functional magnetic resonance imaging. We used a novel behavioral paradigm to investigate time-interval representation in working memory as a function of the temporal jitter and memory load of the sequences containing those time intervals. Human participants were presented with a sequence of intervals and required to reproduce the duration of a particular probed interval. We found that perceptual timing areas including the cerebellum and the striatum were more or less active as a function of increasing and decreasing jitter of the intervals held in working memory respectively whilst the activity of the inferior parietal cortex is modulated as a function of memory load. Additionally, we also analyzed structural correlations between gray and white matter density and behavior and found significant correlations in the cerebellum and the striatum, mirroring the functional results. Our data demonstrate neural substrates of working memory for time intervals and suggest that the cerebellum and the striatum represent core areas for representing temporal information in working memory.

  6. Short-Duration Spaceflight Does Not Prolong QTc Intervals in Male Astronauts

    NASA Technical Reports Server (NTRS)

    Mitchell, Brett M.; Meck, Janice V.

    2004-01-01

    Although ventricular dysrhythmias are not increased during, and QTc intervals are not prolonged after, short-duration (5 to 16 days) spaceflights, QTc intervals have not previously been reported during these shorter flights. Holter monitor recordings, obtained in 11 male astronauts who flew on shuttle missions ranging from 5 to 10 days, showed that QTc intervals did not change significantly 10 days before launch, on 2 separate days of spaceflight, and 2 days after landing. Taken together, these data and our previous report show that QTc interval prolongation occurs sometime between the 9th and 30th days of spaceflight.

  7. Do Longer Intervals between Challenges Reduce the Risk of Adverse Reactions in Oral Wheat Challenges?

    PubMed Central

    Yanagida, Noriyuki; Imai, Takanori; Sato, Sakura; Ebisawa, Motohiro

    2015-01-01

    Background The use of oral food challenges (OFCs) in clinics is limited because they are complicated and associated with anaphylactic symptoms. To increase their use, it is necessary to develop novel, effective, and safe methods. However, the effectiveness of different OFCs has not been compared. Objective To investigate the effect of ingestion methods on wheat allergy symptoms and treatment during OFCs. Method Without changing the total challenge dose, we changed the administration method from a 5-installment dose titration every 15 min (15-min interval method) to 3 installments every 30 min (30-min interval method). We retrospectively reviewed and compared the results of 65 positive 15-min interval wheat challenge tests conducted between July 2005 and February 2008 and 87 positive 30-min interval tests conducted between March 2008 and December 2009. Results A history of immediate symptoms was more common for the 30-min interval method; however, no difference between methods was observed in other background parameters. Switching from the 15-min to the 30-min interval method did not increase symptoms or require treatment. The rate of cardiovascular symptoms (p = 0.032), and adrenaline use (p = 0.017) was significantly lower with the 30-min interval method. The results did not change after adjusting for the effects of immediate symptom history in multivariate analysis. Conclusion This study suggests that the 30-min interval method reduces the risk of adverse events, compared to the 15-min interval method. PMID:26624006

  8. Notes on interval estimation of the generalized odds ratio under stratified random sampling.

    PubMed

    Lui, Kung-Jong; Chang, Kuang-Chao

    2013-05-01

    It is not rare to encounter the patient response on the ordinal scale in a randomized clinical trial (RCT). Under the assumption that the generalized odds ratio (GOR) is homogeneous across strata, we consider four asymptotic interval estimators for the GOR under stratified random sampling. These include the interval estimator using the weighted-least-squares (WLS) approach with the logarithmic transformation (WLSL), the interval estimator using the Mantel-Haenszel (MH) type of estimator with the logarithmic transformation (MHL), the interval estimator using Fieller's theorem with the MH weights (FTMH) and the interval estimator using Fieller's theorem with the WLS weights (FTWLS). We employ Monte Carlo simulation to evaluate the performance of these interval estimators by calculating the coverage probability and the average length. To study the bias of these interval estimators, we also calculate and compare the noncoverage probabilities in the two tails of the resulting confidence intervals. We find that WLSL and MHL can generally perform well, while FTMH and FTWLS can lose either precision or accuracy. We further find that MHL is likely the least biased. Finally, we use the data taken from a study of smoking status and breathing test among workers in certain industrial plants in Houston, Texas, during 1974 to 1975 to illustrate the use of these interval estimators.

  9. Brain Bases of Working Memory for Time Intervals in Rhythmic Sequences

    PubMed Central

    Teki, Sundeep; Griffiths, Timothy D.

    2016-01-01

    Perception of auditory time intervals is critical for accurate comprehension of natural sounds like speech and music. However, the neural substrates and mechanisms underlying the representation of time intervals in working memory are poorly understood. In this study, we investigate the brain bases of working memory for time intervals in rhythmic sequences using functional magnetic resonance imaging. We used a novel behavioral paradigm to investigate time-interval representation in working memory as a function of the temporal jitter and memory load of the sequences containing those time intervals. Human participants were presented with a sequence of intervals and required to reproduce the duration of a particular probed interval. We found that perceptual timing areas including the cerebellum and the striatum were more or less active as a function of increasing and decreasing jitter of the intervals held in working memory respectively whilst the activity of the inferior parietal cortex is modulated as a function of memory load. Additionally, we also analyzed structural correlations between gray and white matter density and behavior and found significant correlations in the cerebellum and the striatum, mirroring the functional results. Our data demonstrate neural substrates of working memory for time intervals and suggest that the cerebellum and the striatum represent core areas for representing temporal information in working memory. PMID:27313506

  10. Multiplicative scale uncertainties in the unified approach for constructing confidence intervals

    SciTech Connect

    Smith, Elton

    2009-01-01

    We have investigated how uncertainties in the estimation of the detection efficiency affect the 90\\% confidence intervals in the unified approach for constructing confidence intervals. The study has been conducted for experiments where the number of detected events is large and can be described by a Gaussian probability density function. We also assume the detection efficiency has a Gaussian probability density and study the range of the relative uncertainties $\\sigma_\\epsilon$ between 0 and 30\\%. We find that the confidence intervals provide proper coverage and increase smoothly and continuously from the intervals that ignore scale uncertainties with a quadratic dependence on $\\sigma_\\epsilon$.

  11. The effect of inter-set rest intervals on resistance exercise-induced muscle hypertrophy.

    PubMed

    Henselmans, Menno; Schoenfeld, Brad J

    2014-12-01

    Due to a scarcity of longitudinal trials directly measuring changes in muscle girth, previous recommendations for inter-set rest intervals in resistance training programs designed to stimulate muscular hypertrophy were primarily based on the post-exercise endocrinological response and other mechanisms theoretically related to muscle growth. New research regarding the effects of inter-set rest interval manipulation on resistance training-induced muscular hypertrophy is reviewed here to evaluate current practices and provide directions for future research. Of the studies measuring long-term muscle hypertrophy in groups employing different rest intervals, none have found superior muscle growth in the shorter compared with the longer rest interval group and one study has found the opposite. Rest intervals less than 1 minute can result in acute increases in serum growth hormone levels and these rest intervals also decrease the serum testosterone to cortisol ratio. Long-term adaptations may abate the post-exercise endocrinological response and the relationship between the transient change in hormonal production and chronic muscular hypertrophy is highly contentious and appears to be weak. The relationship between the rest interval-mediated effect on immune system response, muscle damage, metabolic stress, or energy production capacity and muscle hypertrophy is still ambiguous and largely theoretical. In conclusion, the literature does not support the hypothesis that training for muscle hypertrophy requires shorter rest intervals than training for strength development or that predetermined rest intervals are preferable to auto-regulated rest periods in this regard.

  12. Microsatellite Instability Status of Interval Colorectal Cancers in a Korean Population

    PubMed Central

    Lee, Kil Woo; Park, Soo-Kyung; Yang, Hyo-Joon; Jung, Yoon Suk; Choi, Kyu Yong; Kim, Kyung Eun; Jung, Kyung Uk; Kim, Hyung Ook; Kim, Hungdai; Chun, Ho-Kyung; Park, Dong Il

    2016-01-01

    Background/Aims A subset of patients may develop colorectal cancer after a colonoscopy that is negative for malignancy. These missed or de novo lesions are referred to as interval cancers. The aim of this study was to determine whether interval colon cancers are more likely to result from the loss of function of mismatch repair genes than sporadic cancers and to demonstrate microsatellite instability (MSI). Methods Interval cancer was defined as a cancer that was diagnosed within 5 years of a negative colonoscopy. Among the patients who underwent an operation for colorectal cancer from January 2013 to December 2014, archived cancer specimens were evaluated for MSI by sequencing microsatellite loci. Results Of the 286 colon cancers diagnosed during the study period, 25 (8.7%) represented interval cancer. MSI was found in eight of the 25 patients (32%) that presented interval cancers compared with 22 of the 261 patients (8.4%) that presented sporadic cancers (p=0.002). In the multivariable logistic regression model, MSI was associated with interval cancer (OR, 3.91; 95% confidence interval, 1.38 to 11.05). Conclusions Interval cancers were approximately four times more likely to show high MSI than sporadic cancers. Our findings indicate that certain interval cancers may occur because of distinct biological features. PMID:27114419

  13. Brain Bases of Working Memory for Time Intervals in Rhythmic Sequences.

    PubMed

    Teki, Sundeep; Griffiths, Timothy D

    2016-01-01

    Perception of auditory time intervals is critical for accurate comprehension of natural sounds like speech and music. However, the neural substrates and mechanisms underlying the representation of time intervals in working memory are poorly understood. In this study, we investigate the brain bases of working memory for time intervals in rhythmic sequences using functional magnetic resonance imaging. We used a novel behavioral paradigm to investigate time-interval representation in working memory as a function of the temporal jitter and memory load of the sequences containing those time intervals. Human participants were presented with a sequence of intervals and required to reproduce the duration of a particular probed interval. We found that perceptual timing areas including the cerebellum and the striatum were more or less active as a function of increasing and decreasing jitter of the intervals held in working memory respectively whilst the activity of the inferior parietal cortex is modulated as a function of memory load. Additionally, we also analyzed structural correlations between gray and white matter density and behavior and found significant correlations in the cerebellum and the striatum, mirroring the functional results. Our data demonstrate neural substrates of working memory for time intervals and suggest that the cerebellum and the striatum represent core areas for representing temporal information in working memory. PMID:27313506

  14. Approximate representations of random intervals for hybrid uncertainty quantification in engineering modeling

    SciTech Connect

    Joslyn, C.

    2004-01-01

    We review our approach to the representation and propagation of hybrid uncertainties through high-complexity models, based on quantities known as random intervals. These structures have a variety of mathematical descriptions, for example as interval-valued random variables, statistical collections of intervals, or Dempster-Shafer bodies of evidence on the Borel field. But methods which provide simpler, albeit approximate, representations of random intervals are highly desirable, including p-boxes and traces. Each random interval, through its cumulative belief and plausibility measures functions, generates a unique p-box whose constituent CDFs are all of those consistent with the random interval. In turn, each p-box generates an equivalence class of random intervals consistent with it. Then, each p-box necessarily generates a unique trace which stands as the fuzzy set representation of the p-box or random interval. In turn each trace generates an equivalence class of p-boxes. The heart of our approach is to try to understand the tradeoffs between error and simplicity introduced when p-boxes or traces are used to stand in for various random interval operations. For example, Joslyn has argued that for elicitation and representation tasks, traces can be the most appropriate structure, and has proposed a method for the generation of canonical random intervals from elicited traces. But alternatively, models built as algebraic equations of uncertainty-valued variables (in our case, random-interval-valued) propagate uncertainty through convolution operations on basic algebraic expressions, and while convolution operations are defined on all three structures, we have observed that the results of only some of these operations are preserved as one moves through these three levels of specificity. We report on the status and progress of this modeling approach concerning the relations between these mathematical structures within this overall framework.

  15. Confidence Intervals for True Scores Using the Skew-Normal Distribution

    ERIC Educational Resources Information Center

    Garcia-Perez, Miguel A.

    2010-01-01

    A recent comparative analysis of alternative interval estimation approaches and procedures has shown that confidence intervals (CIs) for true raw scores determined with the Score method--which uses the normal approximation to the binomial distribution--have actual coverage probabilities that are closest to their nominal level. It has also recently…

  16. An approach to solve group-decision-making problems with ordinal interval numbers.

    PubMed

    Fan, Zhi-Ping; Liu, Yang

    2010-10-01

    The ordinal interval number is a form of uncertain preference information in group decision making (GDM), while it is seldom discussed in the existing research. This paper investigates how the ranking order of alternatives is determined based on preference information of ordinal interval numbers in GDM problems. When ranking a large quantity of ordinal interval numbers, the efficiency and accuracy of the ranking process are critical. A new approach is proposed to rank alternatives using ordinal interval numbers when every ranking ordinal in an ordinal interval number is thought to be uniformly and independently distributed in its interval. First, we give the definition of possibility degree on comparing two ordinal interval numbers and the related theory analysis. Then, to rank alternatives, by comparing multiple ordinal interval numbers, a collective expectation possibility degree matrix on pairwise comparisons of alternatives is built, and an optimization model based on this matrix is constructed. Furthermore, an algorithm is also presented to rank alternatives by solving the model. Finally, two examples are used to illustrate the use of the proposed approach. PMID:20172834

  17. Variable-Interval Sequenced-Action Camera (VINSAC). Dissemination Document No. 1.

    ERIC Educational Resources Information Center

    Ward, Ted

    The 16 millimeter (mm) Variable-Interval Sequenced-Action Camera (VINSAC) is designed for inexpensive photographic recording of effective teacher instruction and use of instructional materials for teacher education and research purposes. The camera photographs single frames at preselected time intervals (.5 second to 20 seconds) which are…

  18. Chronic Treatment with Haloperidol Induces Deficits in Working Memory and Feedback Effects of Interval Timing

    ERIC Educational Resources Information Center

    Lustig, C.; Meck, W.H.

    2005-01-01

    Normal participants (n=5) having no experience with antipsychotic drugs and medicated participants (n=5) with clinical experience with chronic low doses of haloperidol (3-10mg/day for 2-4 months) in the treatment of neuroses were evaluated for the effects of inter-trial interval (ITI) feedback on a discrete-trials peak-interval timing procedure.…

  19. Meta-Analytic Interval Estimation for Standardized and Unstandardized Mean Differences

    ERIC Educational Resources Information Center

    Bonett, Douglas G.

    2009-01-01

    The fixed-effects (FE) meta-analytic confidence intervals for unstandardized and standardized mean differences are based on an unrealistic assumption of effect-size homogeneity and perform poorly when this assumption is violated. The random-effects (RE) meta-analytic confidence intervals are based on an unrealistic assumption that the selected…

  20. Evaluating Independent Proportions for Statistical Difference, Equivalence, Indeterminacy, and Trivial Difference Using Inferential Confidence Intervals

    ERIC Educational Resources Information Center

    Tryon, Warren W.; Lewis, Charles

    2009-01-01

    Tryon presented a graphic inferential confidence interval (ICI) approach to analyzing two independent and dependent means for statistical difference, equivalence, replication, indeterminacy, and trivial difference. Tryon and Lewis corrected the reduction factor used to adjust descriptive confidence intervals (DCIs) to create ICIs and introduced…

  1. Computation of the intervals of uncertainties about the parameters found for identification

    NASA Technical Reports Server (NTRS)

    Mereau, P.; Raymond, J.

    1982-01-01

    A modeling method to calculate the intervals of uncertainty for parameters found by identification is described. The region of confidence and the general approach to the calculation of these intervals are discussed. The general subprograms for determination of dimensions are described. They provide the organizational charts for the subprograms, the tests carried out and the listings of the different subprograms.

  2. What Confidence Intervals "Really" Do and Why They Are So Important for Middle Grades Educational Research

    ERIC Educational Resources Information Center

    Skidmore, Susan Troncoso

    2009-01-01

    Recommendations made by major educational and psychological organizations (American Educational Research Association, 2006; American Psychological Association, 2001) call for researchers to regularly report confidence intervals. The purpose of the present paper is to provide support for the use of confidence intervals. To contextualize this…

  3. Computation of Confidence Intervals for Growth Performance in Determination of Safe Harbor Eligibility

    ERIC Educational Resources Information Center

    Mulvenon, Sean W.; Stegman, Charles E.

    2006-01-01

    As part of No Child Left Behind (NCLB) legislation, many states are using confidence intervals to determine a range of scores for evaluating a school system. More specifically, the states are employing confidence intervals to help minimize measurement error in determining a school system's performance. The methodology and techniques employed in…

  4. Performances on ratio and interval schedules of reinforcement: Data and theory.

    PubMed

    Baum, W M

    1993-03-01

    TWO DIFFERENCES BETWEEN RATIO AND INTERVAL PERFORMANCE ARE WELL KNOWN: (a) Higher rates occur on ratio schedules, and (b) ratio schedules are unable to maintain responding at low rates of reinforcement (ratio "strain"). A third phenomenon, a downturn in response rate at the highest rates of reinforcement, is well documented for ratio schedules and is predicted for interval schedules. Pigeons were exposed to multiple variable-ratio variable-interval schedules in which the intervals generated in the variable-ratio component were programmed in the variable-interval component, thereby "yoking" or approximately matching reinforcement in the two components. The full range of ratio performances was studied, from strained to continuous reinforcement. In addition to the expected phenomena, a new phenomenon was observed: an upturn in variable-interval response rate in the midrange of rates of reinforcement that brought response rates on the two schedules to equality before the downturn at the highest rates of reinforcement. When the average response rate was corrected by eliminating pausing after reinforcement, the downturn in response rate vanished, leaving a strictly monotonic performance curve. This apparent functional independence of the postreinforcement pause and the qualitative shift in response implied by the upturn in variable-interval response rate suggest that theoretical accounts will require thinking of behavior as partitioned among at least three categories, and probably four: postreinforcement activity, other unprogrammed activity, ratio-typical operant behavior, and interval-typical operant behavior.

  5. Determination of Reference Intervals for Serum Total Calcium in the Vitamin D-Replete Pediatric Population

    PubMed Central

    Roizen, Jeffrey D.; Shah, Vipul; Levine, Michael A.

    2013-01-01

    Context: Widespread vitamin D insufficiency raises concerns regarding the reliability of reference intervals for serum calcium. Objective: We sought to determine the reference intervals for serum total calcium in pediatric subjects without vitamin D [25-hydroxyvitamin D [25(OH)D

  6. Behavioral contrast in fixed-interval components: effects of extinction-component duration.

    PubMed Central

    de Rose, J C

    1986-01-01

    Seven albino rats were exposed to a multiple schedule of reinforcement in which the two components (fixed interval and extinction) alternated such that a presentation of the extinction component followed each fixed-interval reinforcement. In baseline sessions, the duration of the extinction component was constant and always one-third of the fixed-interval value. Probe sessions contained a probe segment in which the duration of the extinction component was increased; the response rate in fixed-interval components during the probe segment was compared with the response rate in the segments preceding and following the probe. The effect of increasing the duration of the extinction component was studied under three values of fixed interval: 30 s, 120 s, and 18 s, in three successive conditions. Response rate within fixed intervals was a direct function of duration of the extinction component. Pausing at the beginning of the fixed interval decreased as extinction duration increased. These effects were larger and more consistent for the shorter fixed-interval values (18 s and 30 s). These results indicate a functional relation between relative component duration and responding. For the component providing more frequent reinforcement, this could be stated as an inverse relationship between relative component duration and response rate. This relation is similar to findings regarding the ratio of trial and intertrial duration in Pavlovian conditioning procedures, and suggests that behavioral contrast may be related to Pavlovian contingencies underlying the multiple schedule. PMID:3958663

  7. Frequentist evaluation of intervals estimated for a binomial parameter and for the ratio of Poisson means

    NASA Astrophysics Data System (ADS)

    Cousins, Robert D.; Hymes, Kathryn E.; Tucker, Jordan

    2010-01-01

    Confidence intervals for a binomial parameter or for the ratio of Poisson means are commonly desired in high energy physics (HEP) applications such as measuring a detection efficiency or branching ratio. Due to the discreteness of the data, in both of these problems the frequentist coverage probability unfortunately depends on the unknown parameter. Trade-offs among desiderata have led to numerous sets of intervals in the statistics literature, while in HEP one typically encounters only the classic intervals of Clopper-Pearson (central intervals with no undercoverage but substantial over-coverage) or a few approximate methods which perform rather poorly. If strict coverage is relaxed, some sort of averaging is needed to compare intervals. In most of the statistics literature, this averaging is over different values of the unknown parameter, which is conceptually problematic from the frequentist point of view in which the unknown parameter is typically fixed. In contrast, we perform an (unconditional) average over observed data in the ratio-of-Poisson-means problem. If strict conditional coverage is desired, we recommend Clopper-Pearson intervals and intervals from inverting the likelihood ratio test (for central and non-central intervals, respectively). Lancaster's mid- P modification to either provides excellent unconditional average coverage in the ratio-of-Poisson-means problem.

  8. Food and Insulin Effect on QT/QTC Interval of ECG

    ClinicalTrials.gov

    2014-08-19

    Effects of Different Meals on the QT/QTc Interval; Insulin and Oral Hypoglycemic [Antidiabetic] Drugs Causing Adverse Effects in Therapeutic Use; C-Peptide Effects on the QT/QTc Interval; Moxifloxacin ECG Profile in Fed and Fasted State; Japanese vs. Caucasian TQT Comparison

  9. A Comparison of Methods for Estimating Confidence Intervals for Omega-Squared Effect Size

    ERIC Educational Resources Information Center

    Finch, W. Holmes; French, Brian F.

    2012-01-01

    Effect size use has been increasing in the past decade in many research areas. Confidence intervals associated with effect sizes are encouraged to be reported. Prior work has investigated the performance of confidence interval estimation with Cohen's d. This study extends this line of work to the analysis of variance case with more than two…

  10. An evaluation of progressively increasing intertrial intervals on the acquisition and generalization of three social skills.

    PubMed

    Francisco, Monica T; Hanley, Gregory P

    2012-01-01

    We evaluated the effects of different intertrial intervals (ITIs; time between programmed learning opportunities) on the acquisition and generalization of 2 preschoolers' social skills. Independent and generalized skills were observed only when the daily ITI was gradually increased from short to progressively longer intervals.

  11. "Confidence Intervals for Gamma-family Measures of Ordinal Association": Correction

    ERIC Educational Resources Information Center

    Psychological Methods, 2008

    2008-01-01

    Reports an error in "Confidence intervals for gamma-family measures of ordinal association" by Carol M. Woods (Psychological Methods, 2007[Jun], Vol 12[2], 185-204). The note corrects simulation results presented in the article concerning the performance of confidence intervals (CIs) for Spearman's r-sub(s). An error in the author's C++ code…

  12. Resistance to Extinction Following Variable-Interval Reinforcement: Reinforcer Rate and Amount

    ERIC Educational Resources Information Center

    Shull, Richard L.; Grimes, Julie A.

    2006-01-01

    Rats obtained food-pellet reinforcers by nose poking a lighted key. Experiment 1 examined resistance to extinction following single-schedule training with different variable-interval schedules, ranging from a mean interval of 16 min to 0.25 min. That is, for each schedule, the rats received 20 consecutive daily baseline sessions and then a session…

  13. Bouts of Responding on Variable-Interval Schedules: Effects of Deprivation Level

    ERIC Educational Resources Information Center

    Shull, Richard L.

    2004-01-01

    Rats obtained food pellets on a variable-interval schedule of reinforcement by nose poking a lighted key. After training to establish baseline performance (with the mean variable interval set at either 60, 120, or 240 s), the rats were given free access to food during the hour just before their daily session. This satiation operation reduced the…

  14. Notes on interval estimation of the gamma correlation under stratified random sampling.

    PubMed

    Lui, Kung-Jong; Chang, Kuang-Chao

    2012-07-01

    We have developed four asymptotic interval estimators in closed forms for the gamma correlation under stratified random sampling, including the confidence interval based on the most commonly used weighted-least-squares (WLS) approach (CIWLS), the confidence interval calculated from the Mantel-Haenszel (MH) type estimator with the Fisher-type transformation (CIMHT), the confidence interval using the fundamental idea of Fieller's Theorem (CIFT) and the confidence interval derived from a monotonic function of the WLS estimator of Agresti's α with the logarithmic transformation (MWLSLR). To evaluate the finite-sample performance of these four interval estimators and note the possible loss of accuracy in application of both Wald's confidence interval and MWLSLR using pooled data without accounting for stratification, we employ Monte Carlo simulation. We use the data taken from a general social survey studying the association between the income level and job satisfaction with strata formed by genders in black Americans published elsewhere to illustrate the practical use of these interval estimators. PMID:22622622

  15. Post-KR Delay Intervals and Mental Practice: A Test of Adams' Closed Loop Theory

    ERIC Educational Resources Information Center

    Bole, Ronald

    1976-01-01

    The present study suggests that post-KR delay interval time or activity in the interval has little to do with learning on a self-paced positioning task, not ruling out that on ballistic tasks or more complex nonballistic tasks that a learner could make use of additional time or strategy. (MB)

  16. 46 CFR 115.600 - Drydock examination, internal structural examination, and underwater survey intervals.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ..., and underwater survey intervals. 115.600 Section 115.600 Shipping COAST GUARD, DEPARTMENT OF HOMELAND... Drydock examination, internal structural examination, and underwater survey intervals. (a) The owner or..., and underwater surveys required by this section. (b) If your vessel is operated on...

  17. 46 CFR 167.15-30 - Drydock examination, internal structural examination, and underwater survey intervals.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ..., and underwater survey intervals. 167.15-30 Section 167.15-30 Shipping COAST GUARD, DEPARTMENT OF... examination, internal structural examination, and underwater survey intervals. (a) Except as provided for in... an underwater survey (UWILD) under § 167.15-33 of this part. No more than three years may...

  18. A Comparison of Two Reading Fluency Methods: Repeated Readings to a Fluency Criterion and Interval Sprinting

    ERIC Educational Resources Information Center

    Kostewicz, Douglas E.; Kubina, Richard M., Jr.

    2010-01-01

    Teachers have used the method of repeated readings to build oral reading fluency in students with and without special needs. A new fluency building intervention called interval sprinting uses shorter timing intervals (i.e., sprints) across a passage. This study used an alternating treatment design to compare repeated readings and interval…

  19. Interval Estimation for True Raw and Scale Scores under the Binomial Error Model

    ERIC Educational Resources Information Center

    Lee, Won-Chan; Brennan, Robert L.; Kolen, Michael J.

    2006-01-01

    Assuming errors of measurement are distributed binomially, this article reviews various procedures for constructing an interval for an individual's true number-correct score; presents two general interval estimation procedures for an individual's true scale score (i.e., normal approximation and endpoints conversion methods); compares various…

  20. Using Screencast Videos to Enhance Undergraduate Students' Statistical Reasoning about Confidence Intervals

    ERIC Educational Resources Information Center

    Strazzeri, Kenneth Charles

    2013-01-01

    The purposes of this study were to investigate (a) undergraduate students' reasoning about the concepts of confidence intervals (b) undergraduate students' interactions with "well-designed" screencast videos on sampling distributions and confidence intervals, and (c) how screencast videos improve undergraduate students'…

  1. Confidence Intervals for the Mean: To Bootstrap or Not to Bootstrap

    ERIC Educational Resources Information Center

    Calzada, Maria E.; Gardner, Holly

    2011-01-01

    The results of a simulation conducted by a research team involving undergraduate and high school students indicate that when data is symmetric the student's "t" confidence interval for a mean is superior to the studied non-parametric bootstrap confidence intervals. When data is skewed and for sample sizes n greater than or equal to 10, the results…

  2. Sex Differences in the Generalization of Fear as a Function of Retention Intervals

    ERIC Educational Resources Information Center

    Lynch, Joseph, III; Cullen, Patrick K.; Jasnow, Aaron M.; Riccio, David C.

    2013-01-01

    In previous studies using male rodents, context change disrupted a fear response at a short, but not a long, retention interval. Here, we examined the effects of context changes on fear responses as a function of time in male and female rats. Males displayed context discrimination at all intervals, whereas females exhibited generalization by 5 d.…

  3. The Probability of Small Schedule Values and Preference for Random-Interval Schedules

    ERIC Educational Resources Information Center

    Soreth, Michelle Ennis; Hineline, Philip N.

    2009-01-01

    Preference for working on variable schedules and temporal discrimination were simultaneously examined in two experiments using a discrete-trial, concurrent-chains arrangement with fixed interval (FI) and random interval (RI) terminal links. The random schedule was generated by first sampling a probability distribution after the programmed delay to…

  4. The Effects of Initial Interval Size on the Efficacy of DRO Schedules of Reinforcement.

    ERIC Educational Resources Information Center

    Repp, Alan C.; And Others

    1991-01-01

    This study examined effect of initial differential reinforcement of other behavior (DRO) intervals on disruptive behavior of nine students with moderate disabilities. Results indicate initial DRO value equal to the mean number of intervals between responses in baseline was much more effective than a value twice that size. (Author/PB)

  5. An Evaluation of Progressively Increasing Intertrial Intervals on the Acquisition and Generalization of Three Social Skills

    ERIC Educational Resources Information Center

    Francisco, Monica T.; Hanley, Gregory P.

    2012-01-01

    We evaluated the effects of different intertrial intervals (ITIs; time between programmed learning opportunities) on the acquisition and generalization of 2 preschoolers' social skills. Independent and generalized skills were observed only when the daily ITI was gradually increased from short to progressively longer intervals. (Contains 1 figure…

  6. Time intervals for estimating pronghorn and coyote home ranges and daily movements

    SciTech Connect

    Reynolds, T.D. ); Laundre', J.W. )

    1990-04-01

    The authors compared estimates of home range and daily movement for radio-tagged pronghorns (Antilocapra americana) and coyotes (Canis latrans) based on subsamples of data collected at short time intervals during nonconsecutive 24-hour sampling sessions. Home-range size, calculated by either the minimum area method or the linked-cell grid method, and daily distance traveled were underestimated when sampling intervals were based on statistically independent data. Autocorrelated data provided a better estimate of true home-range sizes than independent data for all sampling intervals. Estimates of daily movement based on sampling intervals > 4 hours for pronghorns and >3 hours for coyotes were not correlated with the actual distance traveled. These relationships suggest that restricting sampling effort to statistically independent time intervals sacrifices biologically significant information.

  7. Rate and classification of interval cancers in the breast screening programme.

    PubMed Central

    Sylvester, P. A.; Kutt, E.; Baird, A.; Vipond, M. N.; Webb, A. J.; Farndon, J. R.

    1997-01-01

    There has been concern about the number of interval cancers which have been detected within the National Breast Screening Programme. A series of 134 women presenting with interval cancers was studied by prospective audit and the rate and radiological classification of the tumours determined. The cancers were classified as true (67), false-negative (22), unclassifiable (28), occult (12), and minimal sign (5). The interval cancer rate did not achieve the new National Guidelines in either the first 2 years or the 3rd interval year. The false-negative cancers presented mainly in the 1st interval year, whereas the true cancers were predominantly confined to the 2nd and 3rd years. These data suggest that alterations to the screening programme may be beneficial. It may be, however, that the programme is still on the learning curve and this should be taken into account when interpreting these data. PMID:9244072

  8. Estimation of postmortem interval through albumin in CSF by simple dye binding method.

    PubMed

    Parmar, Ankita K; Menon, Shobhana K

    2015-12-01

    Estimation of postmortem interval is a very important question in some medicolegal investigations. For the precise estimation of postmortem interval, there is a need of a method which can give accurate estimation. Bromocresol green (BCG) is a simple dye binding method and widely used in routine practice. Application of this method in forensic practice may bring revolutionary changes. In this study, cerebrospinal fluid was aspirated from cisternal puncture from 100 autopsies. A study was carried out on concentration of albumin with respect to postmortem interval. After death, albumin present in CSF undergoes changes, after 72 h of death, concentration of albumin has become 0.012 mM, and this decrease was linear from 2 h to 72 h. An important relationship was found between albumin concentration and postmortem interval with an error of ± 1-4h. The study concludes that CSF albumin can be a useful and significant parameter in estimation of postmortem interval.

  9. Representation of interval timing by temporally scalable firing patterns in rat prefrontal cortex

    PubMed Central

    Xu, Min; Zhang, Si-yu; Dan, Yang; Poo, Mu-ming

    2014-01-01

    Perception of time interval on the order of seconds is an essential component of cognition, but the underlying neural mechanism remains largely unknown. In rats trained to estimate time intervals, we found that many neurons in the medial prefrontal cortex (PFC) exhibited sustained spiking activity with diverse temporal profiles of firing-rate modulation during the time-estimation period. Interestingly, in tasks involving different intervals, each neuron exhibited firing-rate modulation with the same profile that was temporally scaled by a factor linearly proportional to the instructed intervals. The behavioral variability across trials within each task also correlated with the intertrial variability of the temporal scaling factor. Local cooling of the medial PFC, which affects neural circuit dynamics, significantly delayed behavioral responses. Thus, PFC neuronal activity contributes to time perception, and temporally scalable firing-rate modulation may reflect a general mechanism for neural representation of interval timing. PMID:24367075

  10. Relationship between plasma calcium and QT interval of electrocardiogram in dairy cows.

    PubMed

    Daniel, R C; Moodie, E W

    1979-06-01

    Relationships between calcium of blood plasma and measurements of the electrocardiogram QT interval corrected for heart rate and interval from Q to the apex of T corrected for heart rate were investigated in six dairy cows. Calcium was varied by infusing 4.7% solution of ethylenediaminetetra-acetic acid disodium salt to induce hypocalcemia, followed by treatment with calcium borogluconate. The within-cow regressions of the intervals on calcium in plasma were significant in all four electrocardiogram leads (leads I, aVF, SIII, and SaVF). These regressions differed between cows in these same leads. Correlation coefficients between calcium and the intervals were consistently larger than --.94 in lead SIII in all cows. When the results from four of the cows similar in age and breed were analyzed separately, regression coefficients between individual cows were not significantly different. However, intervals adjusted for calcium in plasma differed between cows.

  11. Maximum Magnitude and Recurrence Interval for the Large Earthquakes in the Central and Eastern United States

    NASA Astrophysics Data System (ADS)

    Wang, Z.; Hu, C.

    2012-12-01

    Maximum magnitude and recurrence interval of the large earthquakes are key parameters for seismic hazard assessment in the central and eastern United States. Determination of these two parameters is quite difficult in the region, however. For example, the estimated maximum magnitudes of the 1811-12 New Madrid sequence are in the range of M6.6 to M8.2, whereas the estimated recurrence intervals are in the range of about 500 to several thousand years. These large variations of maximum magnitude and recurrence interval for the large earthquakes lead to significant variation of estimated seismic hazards in the central and eastern United States. There are several approaches being used to estimate the magnitudes and recurrence intervals, such as historical intensity analysis, geodetic data analysis, and paleo-seismic investigation. We will discuss the approaches that are currently being used to estimate maximum magnitude and recurrence interval of the large earthquakes in the central United States.

  12. Sampling-interval-dependent stability for linear sampled-data systems with non-uniform sampling

    NASA Astrophysics Data System (ADS)

    Shao, Hanyong; Lam, James; Feng, Zhiguang

    2016-09-01

    This paper is concerned with the sampling-interval-dependent stability of linear sampled-data systems with non-uniform sampling. A new Lyapunov-like functional is constructed to derive sampling-interval-dependent stability results. The Lyapunov-like functional has three features. First, it depends on time explicitly. Second, it may be discontinuous at the sampling instants. Third, it is not required to be positive definite between sampling instants. Moreover, the new Lyapunov-like functional can make use of the information fully of the sampled-data system, including that of both ends of the sampling interval. By making a new proposition for the Lyapunov-like functional, a sampling-interval-dependent stability criterion with reduced conservatism is derived. The new sampling-interval-dependent stability criterion is further extended to linear sampled-data systems with polytopic uncertainties. Finally, examples are given to illustrate the reduced conservatism of the stability criteria.

  13. Inexact rough-interval two-stage stochastic programming for conjunctive water allocation problems.

    PubMed

    Lu, Hongwei; Huang, Guohe; He, Li

    2009-10-01

    An inexact rough-interval two-stage stochastic programming (IRTSP) method is developed for conjunctive water allocation problems. Rough intervals (RIs), as a particular case of rough sets, are introduced into the modeling framework to tackle dual-layer information provided by decision makers. Through embeding upper and lower approximation intervals, rough intervals are capable of reflecting complex parameters with the most reliable and possible variation ranges being identified. An interactive solution method is also derived. A conjunctive water-allocation system is then structured for characterizing the proposed model. Solutions indicate a detailed optimal allocation scheme with a rough-interval form; a total of [[1048.83, 2078.29]:[1482.26, 2020.60

  14. Publication Bias in Meta-Analysis: Confidence Intervals for Rosenthal's Fail-Safe Number

    PubMed Central

    Fragkos, Konstantinos C.; Tsagris, Michail; Frangos, Christos C.

    2014-01-01

    The purpose of the present paper is to assess the efficacy of confidence intervals for Rosenthal's fail-safe number. Although Rosenthal's estimator is highly used by researchers, its statistical properties are largely unexplored. First of all, we developed statistical theory which allowed us to produce confidence intervals for Rosenthal's fail-safe number. This was produced by discerning whether the number of studies analysed in a meta-analysis is fixed or random. Each case produces different variance estimators. For a given number of studies and a given distribution, we provided five variance estimators. Confidence intervals are examined with a normal approximation and a nonparametric bootstrap. The accuracy of the different confidence interval estimates was then tested by methods of simulation under different distributional assumptions. The half normal distribution variance estimator has the best probability coverage. Finally, we provide a table of lower confidence intervals for Rosenthal's estimator. PMID:27437470

  15. Evaluation about the performance of E-government based on interval-valued intuitionistic fuzzy set.

    PubMed

    Zhang, Shuai; Yu, Dejian; Wang, Yan; Zhang, Wenyu

    2014-01-01

    The evaluation is an important approach to promote the development of the E-Government. Since the rapid development of E-Government in the world, the E-Government performance evaluation has become a hot issue in the academia. In this paper, we develop a new evaluation method for the development of the E-Government based on the interval-valued intuitionistic fuzzy set which is a powerful technique in expressing the uncertainty of the real situation. First, we extend the geometric Heronian mean (GHM) operator to interval-valued intuitionistic fuzzy environment and proposed the interval-valued intuitionistic fuzzy GHM (IIFGHM) operator. Then, we investigate the relationships between the IIFGHM operator and some existing ones, such as generalized interval-valued intuitionistic fuzzy HM (GIIFHM) and interval-valued intuitionistic fuzzy weighted Bonferoni mean operator. Furthermore, we validate the effectiveness of the proposed method using a real case about the E-Government evaluation in Hangzhou City, China.

  16. An interval-parameter stochastic robust optimization model for supporting municipal solid waste management under uncertainty

    SciTech Connect

    Xu, Y.; Huang, G.H.; Qin, X.S.; Cao, M.F.; Sun, Y.

    2010-02-15

    A stochastic robust interval linear programming model (IPRO) was developed for supporting municipal solid waste management under uncertainty. The model improves upon the existing stochastic robust optimization (SRO) and interval linear programming (ILP) methods by allowing evaluations of trade-offs among expected costs, cost variability, and risk of violating relax constraints simultaneously, as well as reflections of complex uncertainties through both interval and stochastic theories. A long-term waste management problem was used to demonstrate the applicability of IPRO model. The results indicated that IPRO normally led to interval solutions, where waste-management alternatives could be generated by adjusting the decision-variable values within their intervals. The model could also help waste managers to identify desired policies that under various environmental, economic, system-feasibility and system-reliability constraints.

  17. Does artesunate prolong the electrocardiograph QT interval in patients with severe malaria?

    PubMed

    Maude, Richard J; Plewes, Katherine; Faiz, M Abul; Hanson, Josh; Charunwatthana, Prakaykaew; Lee, Sue J; Tärning, Joel; Yunus, Emran Bin; Hoque, M Gofranul; Hasan, Mahatab Uddin; Hossain, Amir; Lindegardh, Niklas; Day, Nicholas P J; White, Nicholas J; Dondorp, Arjen M

    2009-01-01

    Several antimalarials can cause significant prolongation of the electrocardiograph QT interval, which can be associated with an increased risk of potentially lethal ventricular arrhythmias. High doses of artemether and artemotil have been associated with QT prolongation in dogs, raising the possibility of a class effect with the artemisinin derivatives. Serial electrocardiograms were recorded, and QTc interval was calculated before and after administration of artesunate by intravenous injection in patients with severe falciparum malaria in Bangladesh. Of 21 adult patients with severe malaria enrolled, 8 (38%) died. The mean QTc interval was unaffected by bolus intravenous artesunate (2.4 mg/kg). In two patients, the QTc interval exceeded 0.5 seconds, but in both cases, an alternative explanation was plausible. No effect was observed on the JTc or PR interval, QRS width, blood pressure, or heart rate. Intravenous artesunate does not have significant cardiovascular effects in patients with severe falciparum malaria.

  18. Variations in rupture process with recurrence interval in a repeated small earthquake

    USGS Publications Warehouse

    Vidale, J.E.; Ellsworth, W.L.; Cole, A.; Marone, C.

    1994-01-01

    In theory and in laboratory experiments, friction on sliding surfaces such as rock, glass and metal increases with time since the previous episode of slip. This time dependence is a central pillar of the friction laws widely used to model earthquake phenomena. On natural faults, other properties, such as rupture velocity, porosity and fluid pressure, may also vary with the recurrence interval. Eighteen repetitions of the same small earthquake, separated by intervals ranging from a few days to several years, allow us to test these laboratory predictions in situ. The events with the longest time since the previous earthquake tend to have about 15% larger seismic moment than those with the shortest intervals, although this trend is weak. In addition, the rupture durations of the events with the longest recurrence intervals are more than a factor of two shorter than for the events with the shortest intervals. Both decreased duration and increased friction are consistent with progressive fault healing during the time of stationary contact.In theory and in laboratory experiments, friction on sliding surfaces such as rock, glass and metal increases with time since the previous episode of slip. This time dependence is a central pillar of the friction laws widely used to model earthquake phenomena. On natural faults, other properties, such as rupture velocity, porosity and fluid pressure, may also vary with the recurrence interval. Eighteen repetitions of the same small earthquake, separated by intervals ranging from a few days to several years, allow us to test these laboratory predictions in situ. The events with the longest time since the previous earthquake tend to have about 15% larger seismic moment than those with the shortest intervals, although this trend is weak. In addition, the rupture durations of the events with the longest recurrence intervals are more than a factor of two shorter than for the events with the shortest intervals. Both decreased duration and

  19. Variation in Cancer Incidence among Patients with ESRD during Kidney Function and Nonfunction Intervals.

    PubMed

    Yanik, Elizabeth L; Clarke, Christina A; Snyder, Jon J; Pfeiffer, Ruth M; Engels, Eric A

    2016-05-01

    Among patients with ESRD, cancer risk is affected by kidney dysfunction and by immunosuppression after transplant. Assessing patterns across periods of dialysis and kidney transplantation may inform cancer etiology. We evaluated 202,195 kidney transplant candidates and recipients from a linkage between the Scientific Registry of Transplant Recipients and cancer registries, and compared incidence in kidney function intervals (time with a transplant) with incidence in nonfunction intervals (waitlist or time after transplant failure), adjusting for demographic factors. Incidence of infection-related and immune-related cancer was higher during kidney function intervals than during nonfunction intervals. Incidence was most elevated for Kaposi sarcoma (hazard ratio [HR], 9.1; 95% confidence interval (95% CI), 4.7 to 18), non-Hodgkin's lymphoma (HR, 3.2; 95% CI, 2.8 to 3.7), Hodgkin's lymphoma (HR, 3.0; 95% CI, 1.7 to 5.3), lip cancer (HR, 3.4; 95% CI, 2.0 to 6.0), and nonepithelial skin cancers (HR, 3.8; 95% CI, 2.5 to 5.8). Conversely, ESRD-related cancer incidence was lower during kidney function intervals (kidney cancer: HR, 0.8; 95% CI, 0.7 to 0.8 and thyroid cancer: HR, 0.7; 95% CI, 0.6 to 0.8). With each successive interval, incidence changed in alternating directions for non-Hodgkin's lymphoma, melanoma, and lung, pancreatic, and nonepithelial skin cancers (higher during function intervals), and kidney and thyroid cancers (higher during nonfunction intervals). For many cancers, incidence remained higher than in the general population across all intervals. These data indicate strong short-term effects of kidney dysfunction and immunosuppression on cancer incidence in patients with ESRD, suggesting a need for persistent cancer screening and prevention. PMID:26563384

  20. The dose delivery effect of the different Beam ON interval in FFF SBRT: TrueBEAM

    NASA Astrophysics Data System (ADS)

    Tawonwong, T.; Suriyapee, S.; Oonsiri, S.; Sanghangthum, T.; Oonsiri, P.

    2016-03-01

    The purpose of this study is to determine the dose delivery effect of the different Beam ON interval in Flattening Filter Free Stereotactic Body Radiation Therapy (FFF-SBRT). The three 10MV-FFF SBRT plans (2 half rotating Rapid Arc, 9 to10 Gray/Fraction) were selected and irradiated in three different intervals (100%, 50% and 25%) using the RPM gating system. The plan verification was performed by the ArcCHECK for gamma analysis and the ionization chamber for point dose measurement. The dose delivery time of each interval were observed. For gamma analysis (2%&2mm criteria), the average percent pass of all plans for 100%, 50% and 25% intervals were 86.1±3.3%, 86.0±3.0% and 86.1±3.3%, respectively. For point dose measurement, the average ratios of each interval to the treatment planning were 1.012±0.015, 1.011±0.014 and 1.011±0.013 for 100%, 50% and 25% interval, respectively. The average dose delivery time was increasing from 74.3±5.0 second for 100% interval to 154.3±12.6 and 347.9±20.3 second for 50% and 25% interval, respectively. The same quality of the dose delivery from different Beam ON intervals in FFF-SBRT by TrueBEAM was illustrated. While the 100% interval represents the breath-hold treatment technique, the differences for the free-breathing using RPM gating system can be treated confidently.

  1. Effects of Short-Interval and Long-Interval Swimming Protocols on Performance, Aerobic Adaptations, and Technical Parameters: A Training Study.

    PubMed

    Dalamitros, Athanasios A; Zafeiridis, Andreas S; Toubekis, Argyris G; Tsalis, George A; Pelarigo, Jailton G; Manou, Vasiliki; Kellis, Spiridon

    2016-10-01

    Dalamitros, AA, Zafeiridis, AS, Toubekis, AG, Tsalis, GA, Pelarigo, JG, Manou, V, and Kellis, S. Effects of short-interval and long-interval swimming protocols on performance, aerobic adaptations, and technical parameters: A training study. J Strength Cond Res 30(10): 2871-2879, 2016-This study compared 2-interval swimming training programs of different work interval durations, matched for total distance and exercise intensity, on swimming performance, aerobic adaptations, and technical parameters. Twenty-four former swimmers were equally divided to short-interval training group (INT50, 12-16 × 50 m with 15 seconds rest), long-interval training group (INT100, 6-8 × 100 m with 30 seconds rest), and a control group (CON). The 2 experimental groups followed the specified swimming training program for 8 weeks. Before and after training, swimming performance, technical parameters, and indices of aerobic adaptations were assessed. ΙΝΤ50 and ΙΝΤ100 improved swimming performance in 100 and 400-m tests and the maximal aerobic speed (p ≤ 0.05); the performance in the 50-m swim did not change. Posttraining V[Combining Dot Above]O2max values were higher compared with pretraining values in both training groups (p ≤ 0.05), whereas peak aerobic power output increased only in INT100 (p ≤ 0.05). The 1-minute heart rate and blood lactate recovery values decreased after training in both groups (p < 0.01). Stroke length increased in 100 and 400-m swimming tests after training in both groups (p ≤ 0.05); no changes were observed in stroke rate after training. Comparisons between groups on posttraining mean values, after adjusting for pretraining values, revealed no significant differences between ΙΝΤ50 and ΙΝΤ100 for all variables; however, all measures were improved vs. the respective values in the CON (p < 0.001-0.05). In conclusion, when matched for distance and exercise intensity, the short-interval (50 m) and long-interval (100 m) protocols confer analogous

  2. Preference for less frequent shock under fixed-interval schedules of electric-shock presentation.

    PubMed Central

    Pitts, R C; Malagodi, E F

    1991-01-01

    Lever pressing by 2 squirrel monkeys was maintained under fixed-interval 6-min and fixed-interval 2-min schedules of electric-shock presentation. Preference for these schedules was assessed during three experimental phases. In all phases, responses on one lever produced shock according to one or the other fixed-interval schedule, and responses on a second, changeover, lever switched between schedules. The opportunity to change over was presented during separate choice periods (during which the fixed-interval schedules did not operate) that followed the first through fourth shocks in each schedule. If no changeover occurred during those choice periods, a changeover automatically occurred following the fifth shock. In Phase I, durations of the choice periods were fixed. In Phase II, the choice periods equaled a proportion of their respective fixed interval. During Phase III (completed with 1 monkey) a response on the changeover lever during a given choice period reinstated the most recent fixed interval, and a failure to respond resulted in a changeover. During each of these phases, distinct preferences developed for the 6-min schedule. These results suggest that the maintenance of lever pressing by fixed-interval presentation of electric shock may not be an example of positive reinforcement, and that the response-maintaining characteristics of shock presentation may derive from other properties of the schedule. PMID:1940761

  3. Factors affecting the relationship between calving interval of cows and weaning weights of calves.

    PubMed

    Doren, P E; Long, C R; Cartwright, T C

    1986-05-01

    Characters related to production and reproduction were observed on 744 straightbred and F2 calves and their dams produced in a five-breed diallel with Angus, Brahman, Hereford, Holstein and Jersey breeds. These data were analyzed to estimate the effects of these characters on the relationship between weaning weight and calving interval. The model used for analysis of postpartum conception and calving interval included breedtype, season of conception, parity and management of the dam as main effects; condition of dam nested within parity; and age, weight and weight change of dam and weaning weight of previous calf as covariates. All effects and covariates were significant sources of variation in conception and calving interval. Brahman cows exhibited the longest conception and calving intervals, whereas Hereford X Jersey F1 cows had the shortest intervals. Heterotic effects for these intervals were low and nonsignificant. Weaning weight of the previous calf was positively correlated with postpartum conception and calving interval, but to determine the magnitude of the relationship the need to adjust for differences in breedtype, condition, parity, early management, age, weight and weight change of the dam was apparent. PMID:3722011

  4. Temporal control in rats: analysis of nonlocalized effects from short interfood intervals.

    PubMed

    Higa, J J; Pierson, D

    1998-07-01

    The present experiment analyzed temporal control of postreinforcement pause duration during within-session changes in the criterion for reinforcement (interfood interval, IFI). Analysis of interval-by-interval changes in the pause revealed localized and nonlocalized effects from short intervals that caused specific changes in performance. In Phase 1, rats were presented with five consecutive 15-s IFIs intercalated into a series of 60-s IFIs. The 15-s set decreased the pause in adjacent and more remote 60-s intervals. In Phase 2, two sets of 15-s intervals were intercalated. The spacing between the two sets varied so that 0, 5, 10, or 15 60-s IFIs separated the sets. The postreinforcement pause tracked all changes in the IFI duration, and the localized effect from a short set extended beyond the next interval to the next few 60-s IFIs. Effects from one set, however, did not combine with a second set: Changes in the pause after two sets were the same regardless of the spacing between sets.

  5. Effects of prefeeding, intercomponent-interval food, and extinction on temporal discrimination and pacemaker rate.

    PubMed

    Ward, Ryan D; Odum, Amy L

    2006-02-28

    This experiment investigated the effects of nonpharmacological disruption on temporal discrimination. Pigeons responded on a multiple schedule composed of fixed interval, color-matching, and temporal-discrimination components. The effects of three different disruptors (prefeeding, intercomponent-interval food, and extinction) were assessed. All disruptors decreased response rates during the fixed interval. Prefeeding and intercomponent-interval food had unsystematic effects on response patterning during the fixed interval, whereas extinction increased the relative response rate in the initial portions of the fixed interval. Accuracy of color matching was decreased by prefeeding and was not systematically affected by intercomponent-interval food and extinction. In the temporal-discrimination component, all disruptors flattened the psychophysical functions relating proportion long responses to sample duration. This result indicates a general disruption of temporal discrimination. In addition, parameter estimates derived from the behavioral theory of timing indicated all disruptors decreased pacemaker rate, a result consistent with the predictions of the theory. These results highlight the similarities between disruption of temporal discrimination by pharmacological and nonpharmacological manipulations.

  6. Targeted Estimation of Binary Variable Importance Measures with Interval-Censored Outcomes

    PubMed Central

    van der Laan, Mark J.; Page, Kimberly

    2015-01-01

    In most experimental and observational studies, participants are not followed in continuous time. Instead, data is collected about participants only at certain monitoring times. These monitoring times are random and often participant specific. As a result, outcomes are only known up to random time intervals, resulting in interval-censored data. In contrast, when estimating variable importance measures on interval-censored outcomes, practitioners often ignore the presence of interval censoring, and instead treat the data as continuous or right-censored, applying ad hoc approaches to mask the true interval censoring. In this article, we describe targeted minimum loss–based estimation (TMLE) methods tailored for estimation of binary variable importance measures with interval-censored outcomes. We demonstrate the performance of the interval-censored TMLE procedure through simulation studies and apply the method to analyze the effects of a variety of variables on spontaneous hepatitis C virus clearance among injecton drug users, using data from the “International Collaboration of Incident HIV and HCV in Injecting Cohorts” project. PMID:24637001

  7. Exertional responses to sprint interval training: a comparison of 30-sec. and 60-sec. conditions.

    PubMed

    Kilpatrick, Marcus W; Greeley, Samuel J

    2014-06-01

    The purpose of this study was to assess the effect of sprint interval training on rating of perceived exertion. 20 healthy participants (11 men, 9 women; M age = 23 yr.) completed a maximal cycle ergometer test and two high-intensity interval training cycling sessions. Each session utilized the same work-to-rest ratio (1:1), work intensity (90% max), recovery intensity (10% work intensity), and session duration (16 min.). Trials differed on duration of the interval segment, with a 30-sec. trial and a 60-sec. trial. Sessions required the same amount of total work over the duration of the trial. Rating of perceived exertion assessed before, during, and after exercise were higher for the 60-sec. trial than the 30-sec. trial despite no difference in total work. High intensity interval training trials utilizing the same total external work but differing in interval length produced different ratings of perceived exertion. Perceived exertion is significantly higher for sessions of exercise that utilize longer work intervals. These findings suggest that shorter intervals may produce more favorable exertional responses that could positively affect future behavior.

  8. Important influence of respiration on human R-R interval power spectra is largely ignored.

    PubMed

    Brown, T E; Beightol, L A; Koh, J; Eckberg, D L

    1993-11-01

    Frequency-domain analyses of R-R intervals are used widely to estimate levels of autonomic neural traffic to the human heart. Because respiration modulates autonomic activity, we determined for nine healthy subjects the influence of breathing frequency and tidal volume on R-R interval power spectra (fast-Fourier transform method). We also surveyed published literature to determine current practices in this burgeoning field of scientific inquiry. Supine subjects breathed at rates of 6, 7.5, 10, 15, 17.1, 20, and 24 breaths/min and with nominal tidal volumes of 1,000 and 1,500 ml. R-R interval power at respiratory and low (0.06-0.14 Hz) frequencies declined significantly as breathing frequency increased. R-R interval power at respiratory frequencies was significantly greater at a tidal volume of 1,500 than 1,000 ml. Neither breathing frequency nor tidal volume influenced average R-R intervals significantly. Our review of studies reporting human R-R interval power spectra showed that 51% of the studies controlled respiratory rate, 11% controlled tidal volume, and 11% controlled both respiratory rate and tidal volume. The major implications of our analyses are that breathing parameters strongly influence low-frequency as well as respiratory frequency R-R interval power spectra and that this influence is largely ignored in published research.

  9. A comparison of the impacts of continuous and interval cycle exercise on perceived exertion.

    PubMed

    Kilpatrick, Marcus W; Greeley, Samuel J; Ferron, John M

    2016-01-01

    Ratings of perceived exertion (RPE) were developed to assess exertion during exercise testing. However, assessments of RPE prior to and after exercise have become common and potentially important in understanding exercise behaviour. The purpose of this project was to compare RPE taken before, during and after interval and continuous exercise sessions. Twenty-four participants (12 men, 12 women, body mass index = 24, VO2peak = 41 mL · kg · min(-1)) completed a maximal cycle ergometer test used to prescribe experimental trials: (1) moderate continuous (MC), (2) vigorous continuous (VC), (3) vigorous interval and (4) severe interval. All trials were 20 minutes in length and all intervals utilised 60-second segments and a 1:1 work-to-rest ratio. Predicted exertion was highest in the continuous vigorous trial (p < .05). Exertion increased from beginning to end in all trials (p < .05). Session RPE values were highest for the continuous vigorous trial (p < .05). Findings suggest that interval protocols produce perceptions of effort that are lower than VC exercise but similar to MC exercise. These results help describe the perceptions of effort associated with continuous and interval exercise and suggest that interval exercise can be performed with lower perceived work, which may encourage increased participation.

  10. Radial-interval linear programming for environmental management under varied protection levels.

    PubMed

    Tan, Qian; Huang, Guo H; Cai, Yanpeng

    2010-09-01

    In this study, a radial-interval linear programming (RILP) approach was developed for supporting waste management under uncertainty. RILP improved interval-parameter linear programming and its extensions in terms of input reasonableness and output robustness. From the perspective of modeling inputs, RILP could tackle highly uncertain information at the bounds of interval parameters through introducing the concept of fluctuation radius. Regarding modeling outputs, RILP allows controlling the degree of conservatism associated with interval solutions and is capable of quantifying corresponding system risks and benefits. This could facilitate the reflection of interactive relationship between the feasibility of system and the uncertainty of parameters. A computationally tractable algorithm was provided to solve RILP. Then, a long-term waste management case was studied to demonstrate the applicability of the developed methodology. A series of interval solutions obtained under varied protection levels were compared, helping gain insights into the interactions among protection level, violation risk, and system cost. Potential waste allocation alternatives could be generated from these interval solutions, which would be screened in real-world practices according to various projected system conditions as well as decision-makers' willingness to pay and risk tolerance levels. Sensitivity analysis further revealed the significant impact of fluctuation radii of interval parameters on the system. The results indicated that RILP is applicable to a wide spectrum of environmental management problems that are subject to compound uncertainties.

  11. Important influence of respiration on human R-R interval power spectra is largely ignored

    NASA Technical Reports Server (NTRS)

    Brown, T. E.; Beightol, L. A.; Koh, J.; Eckberg, D. L.

    1993-01-01

    Frequency-domain analyses of R-R intervals are used widely to estimate levels of autonomic neural traffic to the human heart. Because respiration modulates autonomic activity, we determined for nine healthy subjects the influence of breathing frequency and tidal volume on R-R interval power spectra (fast-Fourier transform method). We also surveyed published literature to determine current practices in this burgeoning field of scientific inquiry. Supine subjects breathed at rates of 6, 7.5, 10, 15, 17.1, 20, and 24 breaths/min and with nominal tidal volumes of 1,000 and 1,500 ml. R-R interval power at respiratory and low (0.06-0.14 Hz) frequencies declined significantly as breathing frequency increased. R-R interval power at respiratory frequencies was significantly greater at a tidal volume of 1,500 than 1,000 ml. Neither breathing frequency nor tidal volume influenced average R-R intervals significantly. Our review of studies reporting human R-R interval power spectra showed that 51% of the studies controlled respiratory rate, 11% controlled tidal volume, and 11% controlled both respiratory rate and tidal volume. The major implications of our analyses are that breathing parameters strongly influence low-frequency as well as respiratory frequency R-R interval power spectra and that this influence is largely ignored in published research.

  12. Contextual effects in interval-duration judgements in vision, audition and touch.

    PubMed

    Burr, David; Della Rocca, Eleonora; Rocca, Eleonora Della; Morrone, M Concetta

    2013-09-01

    We examined the effect of temporal context on discrimination of intervals marked by auditory, visual and tactile stimuli. Subjects were asked to compare the duration of the interval immediately preceded by an irrelevant "distractor" stimulus with an interval with no distractor. For short interval durations, the presence of the distractor affected greatly the apparent duration of the test stimulus: short distractors caused the test interval to appear shorter and vice versa. For very short reference durations (≤ 100 ms), the contextual effects were large, changing perceived duration by up to a factor of two. The effect of distractors reduced steadily for longer reference durations, to zero effect for durations greater than 500 ms. We found similar results for intervals defined by visual flashes, auditory tones and brief finger vibrations, all falling to zero effect at 500 ms. Under appropriate conditions, there were strong cross-modal interactions, particularly from audition to vision. We also measured the Weber fractions for duration discrimination and showed that under the conditions of this experiment, Weber fractions decreased steadily with duration, following a square-root law, similarly for all three modalities. The magnitude of the effect of the distractors on apparent duration correlated well with Weber fraction, showing that when duration discrimination was relatively more precise, the context dependency was less. The results were well fit by a simple Bayesian model combining noisy estimates of duration with the action of a resonance-like mechanism that tended to regularize the sound sequence intervals.

  13. Analyzing Systolic-Diastolic Interval Interaction Characteristics in Diabetic Cardiac Autonomic Neuropathy Progression

    PubMed Central

    Imam, Mohammad Hasan; Jelinek, Herbert F.; Palaniswami, Marimuthu; Khandoker, Ahsan H.

    2015-01-01

    Cardiac autonomic neuropathy (CAN), one of the major complications in diabetes, if detected at the subclinical stage allows for effective treatment and avoiding further complication including cardiovascular pathology. Surface ECG (Electrocardiogram)-based diagnosis of CAN is useful to overcome the limitation of existing cardiovascular autonomic reflex tests traditionally used for CAN identification in clinical settings. The aim of this paper is to analyze the changes in the mechanical function of the ventricles in terms of systolic-diastolic interval interaction (SDI) from a surface ECG to assess the severity of CAN progression [no CAN, early CAN (ECAN) or subclinical CAN, and definite CAN (DCAN) or clinical CAN]. ECG signals recorded in supine resting condition from 72 diabetic subjects without CAN (CAN-) and 70 diabetic subjects with CAN were analyzed in this paper. The severity of CAN was determined by Ewing’s Cardiovascular autonomic reflex tests. Fifty-five subjects of the CAN group had ECAN and 15 subjects had DCAN. In this paper, we propose an improved version of the SDI parameter (i.e., TQ/RR interval ratio) measured from the electrical diastolic interval (i.e., TQ interval) and the heart rate interval (i.e., RR interval). The performance of the proposed SDI measure was compared with the performance of the existing SDI measure (i.e., QT/TQ interval ratio). The proposed SDI parameter showed significant differences among three groups (no CAN, ECAN, and DCAN). In addition, the proposed SDI parameter was found to be more sensitive in detecting CAN progression than other ECG interval-based features traditionally used for CAN diagnosis. The modified SDI parameter might be used as an alternative measure for the Ewing autonomic reflex tests to identify CAN progression for those subjects who are unable to perform the traditional tests. These findings could also complement the echocardiographic findings of the left ventricular diastolic dysfunction by providing

  14. Screening intervals for diabetic retinopathy and incidence of visual loss: a systematic review.

    PubMed

    Echouffo-Tcheugui, J B; Ali, M K; Roglic, G; Hayward, R A; Narayan, K M

    2013-11-01

    Screening for diabetic retinopathy can help to prevent this complication, but evidence regarding frequency of screening is uncertain. This paper systematically reviews the published literature on the relationship between screening intervals for diabetic retinopathy and the incidence of visual loss. The PubMed and EMBASE databases were searched until December 2012. Twenty five studies fulfilled the inclusion criteria, as these assessed the incidence/prevalence of sight-threatening diabetic retinopathy in relation to screening frequency. The included studies comprised 15 evaluations of real-world screening programmes, three studies modelling the natural history of diabetic retinopathy and seven cost-effectiveness studies. In evaluations of diabetic retinopathy screening programmes, the appropriate screening interval ranged from one to four years, in people with no retinopathy at baseline. Despite study heterogeneity, the overall tendency observed in these programmes was that 2-year screening intervals among people with no diabetic retinopathy at diagnosis were not associated with high incidence of sight-threatening diabetic retinopathy. The modelling studies (non-economic and economic) assessed a range of screening intervals (1-5 years). The aggregated evidence from both the natural history and cost-effectiveness models favors a screening interval >1 year, but ≤2 years. Such an interval would be appropriate, safe and cost-effective for people with no diabetic retinopathy at diagnosis, while screening intervals ≤1 year would be preferable for people with pre-existing diabetic retinopathy. A 2-year screening interval for people with no sight threatening diabetic retinopathy at diagnosis may be safely adopted. For patients with pre-existing diabetic retinopathy, a shorter interval ≤1 year is warranted.

  15. Nationwide Multicenter Reference Interval Study for 28 Common Biochemical Analytes in China

    PubMed Central

    Xia, Liangyu; Chen, Ming; Liu, Min; Tao, Zhihua; Li, Shijun; Wang, Liang; Cheng, Xinqi; Qin, Xuzhen; Han, Jianhua; Li, Pengchang; Hou, Li’an; Yu, Songlin; Ichihara, Kiyoshi; Qiu, Ling

    2016-01-01

    Abstract A nationwide multicenter study was conducted in the China to explore sources of variation of reference values and establish reference intervals for 28 common biochemical analytes, as a part of the International Federation of Clinical Chemistry and Laboratory Medicine, Committee on Reference Intervals and Decision Limits (IFCC/C-RIDL) global study on reference values. A total of 3148 apparently healthy volunteers were recruited in 6 cities covering a wide area in China. Blood samples were tested in 2 central laboratories using Beckman Coulter AU5800 chemistry analyzers. Certified reference materials and value-assigned serum panel were used for standardization of test results. Multiple regression analysis was performed to explore sources of variation. Need for partition of reference intervals was evaluated based on 3-level nested ANOVA. After secondary exclusion using the latent abnormal values exclusion method, reference intervals were derived by a parametric method using the modified Box–Cox formula. Test results of 20 analytes were made traceable to reference measurement procedures. By the ANOVA, significant sex-related and age-related differences were observed in 12 and 12 analytes, respectively. A small regional difference was observed in the results for albumin, glucose, and sodium. Multiple regression analysis revealed BMI-related changes in results of 9 analytes for man and 6 for woman. Reference intervals of 28 analytes were computed with 17 analytes partitioned by sex and/or age. In conclusion, reference intervals of 28 common chemistry analytes applicable to Chinese Han population were established by use of the latest methodology. Reference intervals of 20 analytes traceable to reference measurement procedures can be used as common reference intervals, whereas others can be used as the assay system-specific reference intervals in China. PMID:26945390

  16. Drug-induced QT interval shortening: potential harbinger of proarrhythmia and regulatory perspectives.

    PubMed

    Shah, Rashmi R

    2010-01-01

    ATP-dependent potassium channel openers such as pinacidil and levcromakalim have long been known to shorten action potential duration and to be profibrillatory in non-clinical models, raising concerns on the clinical safety of drugs that shorten QT interval. Routine non-clinical evaluation of new drugs for their potential to affect cardiac repolarization has revealed that drugs may also shorten QT interval. The description of congenital short QT syndrome in 2000, together with the associated arrhythmias, suggests that drug-induced short QT interval may be proarrhythmic, and an uncanny parallel is evolving between our appreciation of the short and the long QT intervals. Epidemiological studies report an over-representation of short QT interval values in patients with idiopathic ventricular fibrillation. Therefore, as new compounds that shorten QT interval are progressed further into clinical development, questions will inevitably arise on their safety. Arising from the current risk-averse clinical and regulatory environment and concerns on proarrhythmic safety of drugs, together with our lack of a better understanding of the clinical significance of short QT interval, new drugs that substantially shorten QT interval will likely receive an unfavourable regulatory review unless these drugs fulfil an unmet clinical need. This review provides estimates of parameters of QT shortening that may be of potential clinical significance. Rufinamide, a recently approved anticonvulsant, illustrates the current regulatory approach to drugs that shorten QT interval. However, to further substantiate or confirm the safety of these drugs, their approval may well be conditional upon large-scale post-marketing studies with a focus on cardiac safety. PMID:19563537

  17. Ventricular Cycle Length Characteristics Estimative of Prolonged RR Interval during Atrial Fibrillation

    PubMed Central

    CIACCIO, EDWARD J.; BIVIANO, ANGELO B.; GAMBHIR, ALOK; EINSTEIN, ANDREW J.; GARAN, HASAN

    2014-01-01

    Background When atrial fibrillation (AF) is incessant, imaging during a prolonged ventricular RR interval may improve image quality. It was hypothesized that long RR intervals could be predicted from preceding RR values. Methods From the PhysioNet database, electrocardiogram RR intervals were obtained from 74 persistent AF patients. An RR interval lengthened by at least 250 ms beyond the immediately preceding RR interval (termed T0 and T1, respectively) was considered prolonged. A two-parameter scatterplot was used to predict the occurrence of a prolonged interval T0. The scatterplot parameters were: (1) RR variability (RRv) estimated as the average second derivative from 10 previous pairs of RR differences, T13–T2, and (2) Tm–T1, the difference between Tm, the mean from T13 to T2, and T1. For each patient, scatterplots were constructed using preliminary data from the first hour. The ranges of parameters 1 and 2 were adjusted to maximize the proportion of prolonged RR intervals within range. These constraints were used for prediction of prolonged RR in test data collected during the second hour. Results The mean prolonged event was 1.0 seconds in duration. Actual prolonged events were identified with a mean positive predictive value (PPV) of 80% in the test set. PPV was >80% in 36 of 74 patients. An average of 10.8 prolonged RR intervals per 60 minutes was correctly identified. Conclusions A method was developed to predict prolonged RR intervals using two parameters and prior statistical sampling for each patient. This or similar methodology may help improve cardiac imaging in many longstanding persistent AF patients. PMID:23998759

  18. Five-Year Risk of Interval-Invasive Second Breast Cancer

    PubMed Central

    Buist, Diana S. M.; Houssami, Nehmat; Dowling, Emily C.; Halpern, Elkan F.; Gazelle, G. Scott; Lehman, Constance D.; Henderson, Louise M.; Hubbard, Rebecca A.

    2015-01-01

    Background: Earlier detection of second breast cancers after primary breast cancer (PBC) treatment improves survival, yet mammography is less accurate in women with prior breast cancer. The purpose of this study was to examine women presenting clinically with second breast cancers after negative surveillance mammography (interval cancers), and to estimate the five-year risk of interval-invasive second cancers for women with varying risk profiles. Methods: We evaluated a prospective cohort of 15 114 women with 47 717 surveillance mammograms diagnosed with stage 0-II unilateral PBC from 1996 through 2008 at facilities in the Breast Cancer Surveillance Consortium. We used discrete time survival models to estimate the association between odds of an interval-invasive second breast cancer and candidate predictors, including demographic, PBC, and imaging characteristics. All statistical tests were two-sided. Results: The cumulative incidence of second breast cancers after five years was 54.4 per 1000 women, with 325 surveillance-detected and 138 interval-invasive second breast cancers. The five-year risk of interval-invasive second cancer for women with referent category characteristics was 0.60%. For women with the most and least favorable profiles, the five-year risk ranged from 0.07% to 6.11%. Multivariable modeling identified grade II PBC (odds ratio [OR] = 1.95, 95% confidence interval [CI] = 1.15 to 3.31), treatment with lumpectomy without radiation (OR = 3.27, 95% CI = 1.91 to 5.62), interval PBC presentation (OR = 2.01, 95% CI 1.28 to 3.16), and heterogeneously dense breasts on mammography (OR = 1.54, 95% CI = 1.01 to 2.36) as independent predictors of interval-invasive second breast cancers. Conclusions: PBC diagnosis and treatment characteristics contribute to variation in subsequent-interval second breast cancer risk. Consideration of these factors may be useful in developing tailored post-treatment imaging surveillance plans. PMID:25904721

  19. Regularization and control of irregular vehicular motion through a series of signals at disordered intervals

    NASA Astrophysics Data System (ADS)

    Nagatani, Takashi

    2011-06-01

    We study the control and regularization of irregular motion of a vehicle moving through the series of traffic signals positioned at disordered intervals. All signals are controlled by both cycle time and phase shift. The nonlinear dynamic model of the vehicular motion controlled by signals is described in terms of the stochastic nonlinear map. The vehicle exhibits a very complex behavior with varying both cycle time and strength of disordered intervals. The delay or advance of tour time is compensated by synchronizing the phase shift with disordered intervals. The irregular motion induced by the disordered configuration of signals is regularized for various values of cycle time.

  20. Life cycle cost optimization of biofuel supply chains under uncertainties based on interval linear programming.

    PubMed

    Ren, Jingzheng; Dong, Liang; Sun, Lu; Goodsite, Michael Evan; Tan, Shiyu; Dong, Lichun

    2015-01-01

    The aim of this work was to develop a model for optimizing the life cycle cost of biofuel supply chain under uncertainties. Multiple agriculture zones, multiple transportation modes for the transport of grain and biofuel, multiple biofuel plants, and multiple market centers were considered in this model, and the price of the resources, the yield of grain and the market demands were regarded as interval numbers instead of constants. An interval linear programming was developed, and a method for solving interval linear programming was presented. An illustrative case was studied by the proposed model, and the results showed that the proposed model is feasible for designing biofuel supply chain under uncertainties. PMID:25827247

  1. Life cycle cost optimization of biofuel supply chains under uncertainties based on interval linear programming.

    PubMed

    Ren, Jingzheng; Dong, Liang; Sun, Lu; Goodsite, Michael Evan; Tan, Shiyu; Dong, Lichun

    2015-01-01

    The aim of this work was to develop a model for optimizing the life cycle cost of biofuel supply chain under uncertainties. Multiple agriculture zones, multiple transportation modes for the transport of grain and biofuel, multiple biofuel plants, and multiple market centers were considered in this model, and the price of the resources, the yield of grain and the market demands were regarded as interval numbers instead of constants. An interval linear programming was developed, and a method for solving interval linear programming was presented. An illustrative case was studied by the proposed model, and the results showed that the proposed model is feasible for designing biofuel supply chain under uncertainties.

  2. Memory modulation by post-training glucose or insulin remains evident at long retention intervals.

    PubMed

    Kopf, S R; Baratti, C M

    1996-03-01

    Immediate posttraining intraperitoneal injection of alpha-D[+]-glucose (30 mg/kg) facilitated, whereas a nonconvulsive dose of insulin (8 IU/kg) impaired, 24-h retention, in male Swiss mice, of a one-trial step-through inhibitory avoidance task. When mice were trained and received immediate post-training glucose or insulin injections and were tested for retention either 1 week or 1 month later, at each retention interval performance was comparable to that found with a 24-h retention interval. Thus, memory modulation by post-training administration of either glucose or insulin remain evident at long retention intervals. PMID:8833107

  3. Boundary implications for frequency response of interval FIR and IIR filters

    NASA Technical Reports Server (NTRS)

    Bose, N. K.; Kim, K. D.

    1991-01-01

    It is shown that vertex implication results in parameter space apply to interval trigonometric polynomials. Subsequently, it is shown that the frequency responses of both interval FIR and IIR filters are bounded by the frequency responses of certain extreme filters. The results apply directly in the evaluation of properties of designed filters, especially because it is more realistic to bound the filter coefficients from above and below instead of determining those with infinite precision because of finite arithmetic effects. Illustrative examples are provided to show how the extreme filters might be easily derived in any specific interval FIR or IIR filter design problem.

  4. Software sensors for highly uncertain WWTPs: a new approach based on interval observers.

    PubMed

    Alcaraz-González, V; Harmand, J; Rapaport, A; Steyer, J P; González-Alvarez, V; Pelayo-Ortiz, C

    2002-05-01

    This paper presents the practical implementation of a new robust interval observer on a 1 m3 continuous fixed bed anaerobic reactor used for the treatment of industrial wine distillery wastewater. This interval observer is able to generate guaranteed intervals for the unmeasured variables (i.e. acidogenic and methanogenic bacteria, alkalinity and chemical oxygen demand) from few on-line measurements (i.e. input liquid flow rate, CO2 gaseous flow rate, volatile fatty acids and total inorganic carbon). The main advantage of this approach is its independance with respect to disturbances and uncertainty in the initial conditions, in the kinetics and, last but not least, in the process inputs.

  5. Estimation of postmortem interval based on colony development time for Anoplolepsis longipes (Hymenoptera: Formicidae).

    PubMed

    Goff, M L; Win, B H

    1997-11-01

    The postmortem interval for a set of human remains discovered inside a metal tool box was estimated using the development time required for a stratiomyid fly (Diptera: Stratiomyidae), Hermetia illucens, in combination with the time required to establish a colony of the ant Anoplolepsis longipes (Hymenoptera: Formicidae) capable of producing alate (winged) reproductives. This analysis resulted in a postmortem interval estimate of 14 + months, with a period of 14-18 months being the most probable time interval. The victim had been missing for approximately 18 months. PMID:9397565

  6. Estimation of postmortem interval based on colony development time for Anoplolepsis longipes (Hymenoptera: Formicidae).

    PubMed

    Goff, M L; Win, B H

    1997-11-01

    The postmortem interval for a set of human remains discovered inside a metal tool box was estimated using the development time required for a stratiomyid fly (Diptera: Stratiomyidae), Hermetia illucens, in combination with the time required to establish a colony of the ant Anoplolepsis longipes (Hymenoptera: Formicidae) capable of producing alate (winged) reproductives. This analysis resulted in a postmortem interval estimate of 14 + months, with a period of 14-18 months being the most probable time interval. The victim had been missing for approximately 18 months.

  7. Memory modulation by post-training glucose or insulin remains evident at long retention intervals.

    PubMed

    Kopf, S R; Baratti, C M

    1996-03-01

    Immediate posttraining intraperitoneal injection of alpha-D[+]-glucose (30 mg/kg) facilitated, whereas a nonconvulsive dose of insulin (8 IU/kg) impaired, 24-h retention, in male Swiss mice, of a one-trial step-through inhibitory avoidance task. When mice were trained and received immediate post-training glucose or insulin injections and were tested for retention either 1 week or 1 month later, at each retention interval performance was comparable to that found with a 24-h retention interval. Thus, memory modulation by post-training administration of either glucose or insulin remain evident at long retention intervals.

  8. Prediction of left ventricular peak ejection velocity by preceding and prepreceding RR intervals in atrial fibrillation: a new method to adjust the influence between two intervals.

    PubMed Central

    Ko, Hong Sook; Lee, Kwang Je; Kim, Sang Wook; Kim, Tae Ho; Kim, Chee Jeong; Ryu, Wang Seong

    2002-01-01

    In atrial fibrillation, cardiac performance is dependent on both preceding RR (RR-1) and prepreceding RR (RR-2) intervals. However, relative contributions were not well defined. Left ventricular outflow peak ejection velocity (Vpe) was measured by echocardiography from 21 patients. The relation between RR-1 and Vpe could be divided into two zones; steep slope in short RR-1 intervals (< or =0.5 sec) and plateau in long RR-1 intervals (> 0.5 sec). RR-2 had a weak negative association with Vpe. The mean squared correlation coefficient (r2) between RR-2 and Vpe was 0.15 +/-0.13 and improved to 0.29+/-0.21 (p<0.001), when coordinates with RR-1 < or =0.5 sec were excluded. The RR-1 was positively associated with Vpe. The mean r2 between RR-1 and Vpe was 0.52+/-0.17 and improved to 0.72+/-0.11 (p<0.001), when adjusted by RR-2. Simple linear regression analysis showed that mean RR interval, age, fractional shortening (FS), and mean peak velocity were negatively correlated with modified r2 between RR-2 and Vpe. Multiple stepwise regression analysis revealed that mean RR interval (r2=0.32) and FS (r2=0.16) were significant. In summary, simple modification could improve the relationship of both RR-1 and RR-2 with cardiac performance. RR-2 might play a more role in cardiac performance than previously expected, and when cardiac function was impaired. PMID:12482995

  9. The Acute Effects of Interval-Type Exercise on Glycemic Control in Type 2 Diabetes Subjects: Importance of Interval Length. A Controlled, Counterbalanced, Crossover Study

    PubMed Central

    Jakobsen, Ida; Solomon, Thomas P. J.

    2016-01-01

    Interval-type exercise is effective for improving glycemic control, but the optimal approach is unknown. The purpose of this study was to determine the importance of the interval length on changes in postprandial glycemic control following a single exercise bout. Twelve subjects with type 2 diabetes completed a cross-over study with three 1-hour interventions performed in a non-randomized but counter-balanced order: 1) Interval walking consisting of repeated cycles of 3 min slow (aiming for 54% of Peak oxygen consumption rate [VO2peak]) and 3 min fast (aiming for 89% of VO2peak) walking (IW3); 2) Interval walking consisting of repeated cycles of 1 min slow and 1 min fast walking (IW1) and 3) No walking (CON). The exercise interventions were matched with regards to walking speed, and VO2 and heart rate was assessed throughout all interventions. A 4-hour liquid mixed meal tolerance test commenced 30 min after each intervention, with blood samples taken regularly. IW3 and IW1 resulted in comparable mean VO2 and heart rates. Overall mean postprandial blood glucose levels were lower after IW3 compared to CON (10.3±3.0 vs. 11.1±3.3 mmol/L; P < 0.05), with no significant differences between IW1 (10.5±2.8 mmol/L) and CON or IW3 and IW1 (P > 0.05 for both). Conversely blood glucose levels at specific time points during the MMTT differed significantly following both IW3 and IW1 as compared to CON. Our findings support the previously found blood glucose lowering effect of IW3 and suggest that reducing the interval length, while keeping the walking speed and time spend on fast and slow walking constant, does not result in additional improvements. Trial Registration ClinicalTrials.gov NCT02257190 PMID:27695119

  10. Improved confidence intervals for the linkage disequilibrium method for estimating effective population size.

    PubMed

    Jones, A T; Ovenden, J R; Wang, Y-G

    2016-10-01

    The linkage disequilibrium method is currently the most widely used single sample estimator of genetic effective population size. The commonly used software packages come with two options, referred to as the parametric and jackknife methods, for computing the associated confidence intervals. However, little is known on the coverage performance of these methods, and the published data suggest there may be some room for improvement. Here, we propose two new methods for generating confidence intervals and compare them with the two in current use through a simulation study. The new confidence interval methods tend to be conservative but outperform the existing methods for generating confidence intervals under certain circumstances, such as those that may be encountered when making estimates using large numbers of single-nucleotide polymorphisms.

  11. Psycho-Physical Effects of Varied Rest Intervals Following Warm-Up

    ERIC Educational Resources Information Center

    Aronchick, Joel; Burke, Edmund J.

    1977-01-01

    An assessment of the effects of rest intervals of varying lengths following a five minute warm-up revealed no significant differeence among them for perceived exertion, heart rate, and state anxiety. (MB)

  12. Testing independence of bivariate interval-censored data using modified Kendall's tau statistic.

    PubMed

    Kim, Yuneung; Lim, Johan; Park, DoHwan

    2015-11-01

    In this paper, we study a nonparametric procedure to test independence of bivariate interval censored data; for both current status data (case 1 interval-censored data) and case 2 interval-censored data. To do it, we propose a score-based modification of the Kendall's tau statistic for bivariate interval-censored data. Our modification defines the Kendall's tau statistic with expected numbers of concordant and disconcordant pairs of data. The performance of the modified approach is illustrated by simulation studies and application to the AIDS study. We compare our method to alternative approaches such as the two-stage estimation method by Sun et al. (Scandinavian Journal of Statistics, 2006) and the multiple imputation method by Betensky and Finkelstein (Statistics in Medicine, 1999b).

  13. Monitoring molecular interactions using photon arrival-time interval distribution analysis

    DOEpatents

    Laurence, Ted A.; Weiss, Shimon

    2009-10-06

    A method for analyzing/monitoring the properties of species that are labeled with fluorophores. A detector is used to detect photons emitted from species that are labeled with one or more fluorophores and located in a confocal detection volume. The arrival time of each of the photons is determined. The interval of time between various photon pairs is then determined to provide photon pair intervals. The number of photons that have arrival times within the photon pair intervals is also determined. The photon pair intervals are then used in combination with the corresponding counts of intervening photons to analyze properties and interactions of the molecules including brightness, concentration, coincidence and transit time. The method can be used for analyzing single photon streams and multiple photon streams.

  14. 75 FR 5013 - Local Number Portability Porting Interval and Validation Requirements; Telephone Number Portability

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-01

    ... business day porting interval mandated by the Federal Communications Commission. DATES: Comments are due on... From the Federal Register Online via the Government Publishing Office FEDERAL COMMUNICATIONS... Number Portability AGENCY: Federal Communications Commission. ACTION: Proposed rule. SUMMARY:...

  15. Improved confidence intervals for the linkage disequilibrium method for estimating effective population size.

    PubMed

    Jones, A T; Ovenden, J R; Wang, Y-G

    2016-10-01

    The linkage disequilibrium method is currently the most widely used single sample estimator of genetic effective population size. The commonly used software packages come with two options, referred to as the parametric and jackknife methods, for computing the associated confidence intervals. However, little is known on the coverage performance of these methods, and the published data suggest there may be some room for improvement. Here, we propose two new methods for generating confidence intervals and compare them with the two in current use through a simulation study. The new confidence interval methods tend to be conservative but outperform the existing methods for generating confidence intervals under certain circumstances, such as those that may be encountered when making estimates using large numbers of single-nucleotide polymorphisms. PMID:27005004

  16. Preliminary evaluation of a two-interval, two-alternative infant behavioral testing procedurea)

    PubMed Central

    Browning, Jenna; Buss, Emily; Leibold, Lori J.

    2014-01-01

    The purpose of this study was to evaluate the feasibility and efficiency of an observer-based, two-interval forced-choice infant psychophysical testing procedure. Ten of 11 infants (7–9 months of age) achieved a criterion of 80%-correct detection of a 50-dB sound pressure level noise band in a single testing session. Fewer trials were needed to reach criterion using the two-interval procedure than previously reported for the single-interval observer-based psychophysical procedure [Olsho, Koch, Halpin, and Carter (1987). Devel. Psychol. 23, 627–640]. These results provide preliminary evidence that the two-interval procedure is feasible and efficient while controlling for observer and listener response bias. PMID:25190427

  17. Hematologic and serum chemistry reference intervals for free-ranging lions (Panthera leo).

    PubMed

    Maas, Miriam; Keet, Dewald F; Nielen, Mirjam

    2013-08-01

    Hematologic and serum chemistry values are used by veterinarians and wildlife researchers to assess health status and to identify abnormally high or low levels of a particular blood parameter in a target species. For free-ranging lions (Panthera leo) information about these values is scarce. In this study 7 hematologic and 11 serum biochemistry values were evaluated from 485 lions from the Kruger National Park, South Africa. Significant differences between sexes and sub-adult (≤ 36 months) and adult (>36 months) lions were found for most of the blood parameters and separate reference intervals were made for those values. The obtained reference intervals include the means of the various blood parameter values measured in captive lions, except for alkaline phosphatase in the subadult group. These reference intervals can be utilized for free-ranging lions, and may likely also be used as reference intervals for captive lions.

  18. Confidence Intervals for True Scores under an Answer-until-Correct Scoring Procedure.

    ERIC Educational Resources Information Center

    Wilcox, Rand R.

    1987-01-01

    Four procedures are discussed for obtaining a confidence interval when answer-until-correct scoring is used in multiple choice tests. Simulated data show that the choice of procedure depends upon sample size. (GDC)

  19. The effect of ratio and interval training on Pavlovian-instrumental transfer in mice.

    PubMed

    Wiltgen, Brian J; Sinclair, Courtney; Lane, Chadrick; Barrows, Frank; Molina, Martín; Chabanon-Hicks, Chloe

    2012-01-01

    Conditional stimuli (CS) that are paired with reward can be used to motivate instrumental responses. This process is called Pavlovian-instrumental transfer (PIT). A recent study in rats suggested that habitual responses are particularly sensitive to the motivational effects of reward cues. The current experiments examined this idea using ratio and interval training in mice. Two groups of animals were trained to lever press for food pellets that were delivered on random ratio or random interval schedules. Devaluation tests revealed that interval training led to habitual responding while ratio training produced goal-directed actions. The presentation of CSs paired with reward led to positive transfer in both groups, however, the size of this effect was much larger in mice that were trained on interval schedules. This result suggests that habitual responses are more sensitive to the motivational influence of reward cues than goal-directed actions. The implications for neurobiological models of motivation and drug seeking behaviors are discussed.

  20. Improved Power Saving Mechanism to Increase Unavailability Interval in IEEE 802.16e Networks

    NASA Astrophysics Data System (ADS)

    Lee, Kyunghye; Mun, Youngsong

    To manage limited energy resources efficiently, IEEE 802.16e specifies sleep mode operation. Since there can be no communication between the mobile station (MS) and the serving base station (BS) during the unavailability interval, the MS can power down its physical operation components. We propose an improved power saving mechanism (iPSM) which effectively increases the unavailability interval of Type I and Type II power saving classes (PSCs) activated in an MS. After investigating the number of frames in the unavailability interval of each Type II PSC when used with Type I PSC, the iPSM chooses the Type II PSC that yields the maximum number of frames in the unavailability interval. Performance evaluation confirms that the proposed scheme is very effective.