Science.gov

Sample records for 5-minute reaction time

  1. 5 experiments in 5 minutes

    NASA Astrophysics Data System (ADS)

    Hut, Rolf

    2015-04-01

    Show, don't tell. When kids ask about your research, show, don't tell. We, the ambassadors of science, shouldn't be boring our nieces and nephews at family dinners with parameter distributions, we should make them excited about science. Getting people excited: show, don't tell. In 5 minutes, I will perform 5 experiments that anyone can do using everyday household items to get kids interested in science. Bring safety glasses.

  2. 39 CFR 6.5 - Minutes of meetings.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Service UNITED STATES POSTAL SERVICE THE BOARD OF GOVERNORS OF THE U.S. POSTAL SERVICE MEETINGS (ARTICLE VI) § 6.5 Minutes of meetings. The Secretary shall preserve the minutes of Board meetings prepared under § 4.6 of these bylaws. After the minutes of any meeting are approved by the Board, the...

  3. The Variance Reaction Time Model

    ERIC Educational Resources Information Center

    Sikstrom, Sverker

    2004-01-01

    The variance reaction time model (VRTM) is proposed to account for various recognition data on reaction time, the mirror effect, receiver-operating-characteristic (ROC) curves, etc. The model is based on simple and plausible assumptions within a neural network: VRTM is a two layer neural network where one layer represents items and one layer…

  4. Guidelines for measuring reaction time.

    PubMed

    Crabtree, D A; Antrim, L R

    1988-04-01

    Although reaction time is one of the most common measures of neurological function, protocols often do not take into consideration many of the extraneous factors that may invalidate such assessments. This paper discusses several issues related to matters of instrumentation, subject control, design of assessment, and interpretation. Twenty recommendations are provided as a guideline for those who assess reaction time of clients or patients. While these suggestions are not proposed as definitive or complete, the points should serve as a guide to young researchers as well as a checklist for more seasoned experimenters.

  5. Operational Solar Forecasting System for DNI and GHI for Horizons Covering 5 Minutes to 72 Hours

    NASA Astrophysics Data System (ADS)

    Coimbra, C. F.

    2014-12-01

    I will describe the methodology used to develop and deploy operationally a comprehensive solar forecasting system for both concentrated and non-concentrated solar technologies. This operational forecasting system ingests data from local telemetry, remote sensing and Numerical Weather Prediction (NWP) models, processes all the diferent types of data (time series, sky images, satellite images, gridded data, etc.) to produce concatenated solar forecasts from 5 minutes out to 72 hours into the future. Each forecast is optimized with stochastic learning techniques that include input selection, model topology optimization, model output statistics, metric fitness optimization and machine learning. These forecasts are used by solar generators (plant managers), utilities and independent system operators for operations, scheduling, dispatching and market participation.

  6. The Discovery of the Solar 5-minute Oscillations and the Supergranulation

    NASA Astrophysics Data System (ADS)

    Noyes, Robert W.

    2014-06-01

    The summer of 1960 marked the discovery, from the Mt. Wilson 60-foot solar tower telescope, of both the solar 5-minute oscillation and the supergranulation. We review the history of how, starting in 1955, Robert Leighton at Caltech carried out studies of the sun at high resolution from the Mt. Wilson 60-foot solar tower telescope. In 1958 he developed a method to map the spatial distribution of solar magnetic fields by photographically subtracting pairs of spectroheliograph images differing only in the sign of their Zeeman-effect sensitivity to longitudinal magnetic fields, and showed for the first time that photospheric magnetic fields trace out the heating of the overlying chromosphere as revealed by the pattern of the Ca II emission network. Leighton then developed a variation of the technique to measure velocity fields and their spatial and temporal variation, and in the summer of 1960 he and his students made a series of discoveries that changed the face of solar physics. One of these was the discovery that the velocity field of the sun exhibits a very strong quasi-periodic vertical oscillation with a period of about 5 minutes; this discovery represents the dawn of helioseismology, which over the past 50 years has grown to embrace research lines in solar and stellar astrophysics that were unimaginable at the time. A parallel discovery made by Leighton and his students during that same summer was the "large cells", later to be termed the supergranulation, which show a complex pattern of flow fields, evidently produced bylarge-scale convective motions that are still not well-understood, but which create the magnetic network and hence the pattern of heating in the overlying chromosphere.

  7. Comparison of 7.5-minute and 1-degree digital elevation models

    NASA Technical Reports Server (NTRS)

    Isaacson, Dennis L.; Ripple, William J.

    1995-01-01

    We compared two digital elevation models (DEM's) for the Echo Mountain SE quadrangle in the Cascade Mountains of Oregon. Comparisons were made between 7.5-minute (1:24,000-scale) and 1-degree (1:250,000-scale) images using the variables of elevation, slope aspect, and slope gradient. Both visual and statistical differences are presented.

  8. Time scale in quasifission reactions

    SciTech Connect

    Back, B.B.; Paul, P.; Nestler, J.

    1995-08-01

    The quasifission process arises from the hindrance of the complete fusion process when heavy-ion beams are used. The strong dissipation in the system tends to prevent fusion and lead the system towards reseparation into two final products of similar mass reminiscent of a fission process. This dissipation slows down the mass transfer and shape transformation and allows for the emission of high energy {gamma}-rays during the process, albeit with a low probability. Giant Dipole {gamma} rays emitted during this time have a characteristic spectral shape and may thus be discerned in the presence of a background of {gamma} rays emitted from the final fission-like fragments. Since the rate of GDR {gamma} emission is very well established, the strength of this component may therefore be used to measure the timescale of the quasifission process. In this experiment we studied the reaction between 368-MeV {sup 58}Ni and a {sup 165}Ho target, where deep inelastic scattering and quasifission processes are dominant. Coincidences between fission fragments (detected in four position-sensitive avalanche detectors) and high energy {gamma} rays (measured in a 10{close_quotes} x 10{close_quotes} actively shielded NaI detector) were registered. Beams were provided by the Stony Brook Superconducting Linac. The {gamma}-ray spectrum associated with deep inelastic scattering events is well reproduced by statistical cooling of projectile and target-like fragments with close to equal initial excitation energy sharing. The y spectrum associated with quasifission events is well described by statistical emission from the fission fragments alone, with only weak evidence for GDR emission from the mono-nucleus. A 1{sigma} limit of t{sub ss} < 11 x 10{sup -21} s is obtained for the mono-nucleus lifetime, which is consistent with the lifetime obtained from quasifission fragment angular distributions. A manuscript was accepted for publication.

  9. Reaction Time and Anticipation Time: Effects of Development.

    ERIC Educational Resources Information Center

    Thomas, Jerry R.; And Others

    1981-01-01

    Results of a study indicated that, as age increased from seven to 20 years, reaction time decreased, with males having a more rapid reaction time than females. Beginning at age 10 or 11, subjects developed better motor plans and relied less on rapid reaction time to achieve good anticipation time. (FG)

  10. Geologic map of the Battle Ground 7.5-minute quadrangle, Clark County, Washington

    USGS Publications Warehouse

    Howard, Keith A.

    2002-01-01

    This digital map database, compiled from previously published and unpublished data, and new mapping by the authors, represents the general distribution of bedrock and surficial deposits of the Battle Ground 7.5 minute quadrangle. The database delineates map units that are identified by general age and lithology following the stratigraphic nomenclature of the U.S. Geological Survey. The scale of the source maps limits the spatial resolution (scale) of the database to 1:24,000 or smaller.

  11. A revised 5 minute gravimetric geoid and associated errors for the North Atlantic calibration area

    NASA Technical Reports Server (NTRS)

    Mader, G. L.

    1979-01-01

    A revised 5 minute gravimetric geoid and its errors were computed for the North Atlantic calibration area using GEM-8 potential coefficients and the latest gravity data available from the Defense Mapping Agency. This effort was prompted by a number of inconsistencies and small errors found in previous calculations of this geoid. The computational method and constants used are given in detail to serve as a reference for future work.

  12. Geology of the Southeast Durham and Southwest Durham 7. 5-minute Quadrangles, North Carolina

    SciTech Connect

    Hoffman, C.W.; Gallagher, P.E.

    1989-01-01

    The Southeast Durham and Southwest Durham 7.5-minute Quadrangles include a 26 kilometer transect of the Durham Triassic basin from the Jonesboro fault on the southeastern side of this half-graben structure to a bounding unconformity on the northwestern side. The basin is filled with non-marine, primarily fluvial, clastic deposits of the Late Triassic Chatham Group. The Chatham Group rocks are intruded by Early Jurassic diabase as dikes and sheets. Bordering rocks are pre-Mesozoic intrusive, metavolcanic and metasedimentary rocks of the Carolina slate belt. This paper discusses the geology of the Southeast Durham and Southwest Durham Quadrangles. 37 refs., 17 figs.

  13. The 2.5-minute loaded repeated jump test: evaluating anaerobic capacity in alpine ski racers with loaded countermovement jumps.

    PubMed

    Patterson, Carson; Raschner, Christian; Platzer, Hans-Peter

    2014-09-01

    The purposes of this study were to test the reproducibility of the 2.5-minute loaded repeated jump test (LRJT) and to test the effectiveness of general preparation period (GPP) training on anaerobic fitness of elite alpine ski racers with the LRJT. Thirteen male volunteers completed 2 LRJTs to examine reliability. Nine male Austrian elite junior racers were tested in June and October 2009. The LRJT consisted of 60 loaded countermovement jumps (LCMJs) with a loaded barbell equivalent to 40% bodyweight. Before the LRJT, the power (P) of a single LCMJ was determined. Power was calculated from ground reaction forces. The mean P was calculated for the complete test and for each 30-second interval. The interclass correlation coefficients (between 0.88 and 0.99) for main variables of the LRJT demonstrated a high reliability. A repeated-measures analysis of variance indicated that anaerobic capacity was significantly higher in October (p ≤ 0.05). The ski racers' single LCMJ P increased from 37.0 ± 1.2 W·kg to 39.0 ± 1.4 W·kg. The mean P of the total test improved from 33.6 ± 1.2 W·kg to 35.8 ± 1.3 W·kg, but relative effect of fatigue did not change. The GPP training improved the athletes' ability to produce and maintain muscular power. The LRJT is a reliable anaerobic test suitable for all alpine ski racing events because the 60 jumps simulate the approximate number of gates in slalom and giant slalom races and the 2.5 minutes is equivalent to the duration of the longest downhill race.

  14. Connectionist and diffusion models of reaction time.

    PubMed

    Ratcliff, R; Van Zandt, T; McKoon, G

    1999-04-01

    Two connectionist frameworks, GRAIN (J. L. McClelland, 1993) and brain-state-in-a-box (J. A. Anderson, 1991), and R. Ratcliff's (1978) diffusion model were evaluated using data from a signal detection task. Dependent variables included response probabilities, reaction times for correct and error responses, and shapes of reaction-time distributions. The diffusion model accounted for all aspects of the data, including error reaction times that had previously been a problem for all response-time models. The connectionist models accounted for many aspects of the data adequately, but each failed to a greater or lesser degree in important ways except for one model that was similar to the diffusion model. The findings advance the development of the diffusion model and show that the long tradition of reaction-time research and theory is a fertile domain for development and testing of connectionist assumptions about how decisions are generated over time.

  15. Geologic map of the Morena Reservoir 7.5-minute quadrangle, San Diego County, California

    USGS Publications Warehouse

    Todd, Victoria R.

    2016-06-01

    IntroductionMapping in the Morena Reservoir 7.5-minute quadrangle began in 1980, when the Hauser Wilderness Area, which straddles the Morena Reservoir and Barrett Lake quadrangles, was mapped for the U.S. Forest Service. Mapping was completed in 1993–1994. The Morena Reservoir quadrangle contains part of a regional-scale Late Jurassic(?) to Early Cretaceous tectonic suture that coincides with the western limit of Jurassic metagranites in this part of the Peninsular Ranges batholith (PRB). This suture, and a nearly coincident map unit consisting of metamorphosed Cretaceous and Jurassic back-arc basinal volcanic and sedimentary rocks (unit KJvs), mark the boundary between western, predominantly metavolcanic rocks, and eastern, mainly metasedimentary, rocks. The suture is intruded and truncated by the western margin of middle to Late Cretaceous Granite Mountain and La Posta plutons of the eastern zone of the batholith.

  16. Intensive baseball practice improves the Go/Nogo reaction time, but not the simple reaction time.

    PubMed

    Kida, Noriyuki; Oda, Shingo; Matsumura, Michikazu

    2005-02-01

    Baseball hitters are required to make decisions whether to swing or not as quickly as possible. Therefore, we can assume that skilled baseball players have a quicker response. To verify this hypothesis, we assessed the effect of baseball experience or skill levels on simple reaction times and Go/Nogo reaction times in 82 university students (22 baseball players, 22 tennis players, and 38 nonathletes) and 17 professional baseball players. Also, to clarify whether this ability was innate or acquired, we examined the effects of long-term practice for baseball hitting in 94 senior high school students (26 baseball players and 68 non-baseball players). There were no differences in simple reaction time either for sports experience or for skill levels. On the contrary, the Go/Nogo reaction time for baseball players was significantly shorter than that of the tennis players and nonathletes. The Go/Nogo reaction time of higher-skill baseball players was significantly shorter than that of lower-skill players, while that of the professional baseball players was the shortest. The professional players showed the highest (almost linear) correlation between the Go/Nogo reaction time and simple reaction time. A longitudinal study showed that 2 years of hitting practice improved the Go/Nogo reaction time, while the simple reaction time remained constant. A cross-sectional study of high school non-baseball players showed no differences either in the simple or Go/Nogo reaction times in relation to school year. In conclusion, intensive practice, including Go or Nogo decision making, improved the Go/Nogo reaction time, but not the simple reaction time. PMID:15653298

  17. Intensive baseball practice improves the Go/Nogo reaction time, but not the simple reaction time.

    PubMed

    Kida, Noriyuki; Oda, Shingo; Matsumura, Michikazu

    2005-02-01

    Baseball hitters are required to make decisions whether to swing or not as quickly as possible. Therefore, we can assume that skilled baseball players have a quicker response. To verify this hypothesis, we assessed the effect of baseball experience or skill levels on simple reaction times and Go/Nogo reaction times in 82 university students (22 baseball players, 22 tennis players, and 38 nonathletes) and 17 professional baseball players. Also, to clarify whether this ability was innate or acquired, we examined the effects of long-term practice for baseball hitting in 94 senior high school students (26 baseball players and 68 non-baseball players). There were no differences in simple reaction time either for sports experience or for skill levels. On the contrary, the Go/Nogo reaction time for baseball players was significantly shorter than that of the tennis players and nonathletes. The Go/Nogo reaction time of higher-skill baseball players was significantly shorter than that of lower-skill players, while that of the professional baseball players was the shortest. The professional players showed the highest (almost linear) correlation between the Go/Nogo reaction time and simple reaction time. A longitudinal study showed that 2 years of hitting practice improved the Go/Nogo reaction time, while the simple reaction time remained constant. A cross-sectional study of high school non-baseball players showed no differences either in the simple or Go/Nogo reaction times in relation to school year. In conclusion, intensive practice, including Go or Nogo decision making, improved the Go/Nogo reaction time, but not the simple reaction time.

  18. Dynamic Parameters Variability: Time Interval Interference on Ground Reaction Force During Running.

    PubMed

    Pennone, Juliana; Mezêncio, Bruno; Amadio, Alberto C; Serrão, Júlio C

    2016-04-01

    The aim of this study was to determine the effect of the time between measures on ground reaction force running variability; 15 healthy men (age = 23.8 ± 3.7 years; weight = 72.8 ± 7.7 kg; height 174.3 ± 8.4 cm) performed two trials of running 45 minutes at 9 km/hr at intervals of seven days. The ground reaction forces were recorded every 5 minutes. The coefficients of variation of indicative parameters of the ground reaction forces for each condition were compared. The coefficients of variations of the ground reaction forces curve analyzed between intervals and sessions were 21.9% and 21.48%, respectively. There was no significant difference for the ground reaction forces parameters Fy1, tFy1, TC1, Imp50, Fy2, and tFy2 between intervals and sessions. Although the ground reaction forces variables present a natural variability, this variability in intervals and in sessions remained consistent, ensuring a high reliability in repeated measures designs.

  19. Time-Dependent Molecular Reaction Dynamics

    NASA Astrophysics Data System (ADS)

    Öhrn, Yngve

    2007-11-01

    This paper is a brief review of a time-dependent, direct, nonadiabatic theory of molecular processes called Electron Nuclear Dynamics (END). This approach to the study of molecular reaction dynamics is a hierarchical theory that can be applied at various levels of approximation. The simplest level of END uses classical nuclei and represents all electrons by a single, complex, determinantal wave function. The wave function parameters such as average nuclear positions and momenta, and molecular orbital coefcients carry the time dependence and serve as dynamical variables. Examples of application are given of the simplest level of END to ion-atom and ion-molecule reactions.

  20. Evaluating Warning Sound Urgency with Reaction Times

    ERIC Educational Resources Information Center

    Suied, Clara; Susini, Patrick; McAdams, Stephen

    2008-01-01

    It is well-established that subjective judgments of perceived urgency of alarm sounds can be affected by acoustic parameters. In this study, the authors investigated an objective measurement, the reaction time (RT), to test the effectiveness of temporal parameters of sounds in the context of warning sounds. Three experiments were performed using a…

  1. IQ, Reaction Time and the Differentiation Hypothesis.

    ERIC Educational Resources Information Center

    Der, Geoff; Deary, Ian J.

    2003-01-01

    Explored the relationship of both simple and four-choice reaction time to scores for the Alice Heim 4 (AH4) test to assess whether correlations previously reported adequately represented the strength of the relationship and to test for departures from linearity. Findings for 900 adolescents and adult show the correlation to be a good summary for…

  2. Effective Analysis of Reaction Time Data

    ERIC Educational Resources Information Center

    Whelan, Robert

    2008-01-01

    Most analyses of reaction time (RT) data are conducted by using the statistical techniques with which psychologists are most familiar, such as analysis of variance on the sample mean. Unfortunately, these methods are usually inappropriate for RT data, because they have little power to detect genuine differences in RT between conditions. In…

  3. Deciphering Time Scale Hierarchy in Reaction Networks.

    PubMed

    Nagahata, Yutaka; Maeda, Satoshi; Teramoto, Hiroshi; Horiyama, Takashi; Taketsugu, Tetsuya; Komatsuzaki, Tamiki

    2016-03-01

    Markovian dynamics on complex reaction networks are one of the most intriguing subjects in a wide range of research fields including chemical reactions, biological physics, and ecology. To represent the global kinetics from one node (corresponding to a basin on an energy landscape) to another requires information on multiple pathways that directly or indirectly connect these two nodes through the entire network. In this paper we present a scheme to extract a hierarchical set of global transition states (TSs) over a discrete-time Markov chain derived from first-order rate equations. The TSs can naturally take into account the multiple pathways connecting any pair of nodes. We also propose a new type of disconnectivity graph (DG) to capture the hierarchical organization of different time scales of reactions that can capture changes in the network due to changes in the time scale of observation. The crux is the introduction of the minimum conductance cut (MCC) in graph clustering, corresponding to the dividing surface across the network having the "smallest" transition probability between two disjoint subnetworks (superbasins on the energy landscape) in the network. We present a new combinatorial search algorithm for finding this MCC. We apply our method to a reaction network of Claisen rearrangement of allyl vinyl ether that consists of 23 nodes and 66 links (saddles on the energy landscape) connecting them. We compare the kinetic properties of our DG to those of the transition matrix of the rate equations and show that our graph can properly reveal the hierarchical organization of time scales in a network. PMID:26641663

  4. A comparison of 5-minute povidone-iodine scrub and 1-minute povidone-iodine scrub followed by alcohol foam.

    PubMed

    Deshmukh, N; Kramer, J W; Kjellberg, S I

    1998-03-01

    The purpose of this study was to determine if a 1-minute scrub with povidone-iodine followed by alcohol foam is as effective as a 5-minute scrub with povidone-iodine in reducing skin bacterial counts. A 1-minute scrub with povidone-iodine followed by alcohol foam and a 5-minute scrub with povidone-iodine was done. In the first study, cultures were obtained after 1 hour, and in the second study, cultures were obtained after 2 hours. Cultures were obtained by imprinting the first, second, and third fingers on nutrient agar plates. Bacterial counts were then obtained at 24 and 48 hours. The study involved two groups of 12 participants and a total of 37 patients over a period of 5 months. The results show that there was no significant difference between the number of colonies cultured for the 1-minute scrub compared with the 5-minute scrub for either the 1-hour or the 2-hour study. In fact, the total number of bacterial colonies was less after the 1-minute scrub with alcohol foam than after the standard 5-minute scrub in both the 1-hour group (10 vs. 18) and the 2-hour group (18 vs. 44).

  5. Geologic map and digital database of the Pinto Mountain 7.5 minute quadrangle, Riverside County, California

    USGS Publications Warehouse

    Powell, Robert E.

    2002-01-01

    The geologic map and digital database of the Pinto Mountain quadrangle are products of a regional geologic mapping effort undertaken in the eastern Transverse Ranges in and around Joshua Tree National Park. This investigation, part of the Southern California Areal Mapping Project (SCAMP), is conducted in cooperation with the California Geologic Survey and the National Park Service. In line with the goals of the National Cooperative Geologic Mapping Program (NCGMP), mapping of the Pinto Mountain and other quadrangles has been directed toward generating a multipurpose digital geologic map database that is applicable to land-related investigations in the earth and biological sciences. This mapping is conducted to further understanding of bedrock geology and surficial processes in the region and to document evidence for seismotectonic activity in the eastern Transverse Ranges. It is also intended to serve as a base layer suitable for ecosystem and mineral resource assessment and for building a hydrogeologic framework for Pinto Basin. Initial investigations span Pinto Basin from the Hexie and Eagle Mountains northward into the Pinto Mountains. Quadrangles mapped include the Conejo Well 7.5-minute quadrangle (Powell, 2001a), the Porcupine Wash 7.5-minute quadrangle (Powell, 2001b), the Pinto Mountain 7.5-minute quadrangle, and the San Bernardino Wash 7.5-minute quadrangle (Powell, 2002). Parts of the Pinto Mountain quadrangle had been mapped previously at a variety of scales (Weir, and Bader, 1963; Hope, 1966, 1969; Jennings, 1967; Powell, 1981, 1993).

  6. Geologic map and digital database of the San Bernardino Wash 7.5 minute quadrangle, Riverside County, California

    USGS Publications Warehouse

    Powell, Robert E.; digital preparation by Cossette, Pamela M.

    2002-01-01

    The geologic map and digital database of the San Bernardino Wash quadrangle are products of a regional geologic mapping effort undertaken in the eastern Transverse Ranges in and around Joshua Tree National Park. This investigation, part of the Southern California Areal Mapping Project (SCAMP), is conducted in cooperation with the California Geologic Survey and the National Park Service. In line with the goals of the National Cooperative Geologic Mapping Program (NCGMP), mapping of the San Bernardino Wash and other quadrangles has been directed toward generating a multipurpose digital geologic map database that is applicable to land-related investigations in the earth and biological sciences. This mapping is conducted to further understanding of bedrock geology and surficial processes in the region and to document evidence for seismotectonic activity in the eastern Transverse Ranges. It is also intended to serve as a base layer suitable for ecosystem and mineral resource assessment and for building a hydrogeologic framework for Pinto Basin. Initial investigations span Pinto Basin from the Hexie and Eagle Mountains northward into the Pinto Mountains (see fig. 1). Quadrangles mapped include the Conejo Well 7.5-minute quadrangle (Powell, 2001a), the Porcupine Wash 7.5-minute quadrangle (Powell, 2001b), the Pinto Mountain 7.5-minute quadrangle (Powell, 2002), and the San Bernardino Wash 7.5-minute quadrangle. Parts of the San Bernardino Wash quadrangle had been mapped previously at a variety of scales (Weir, and Bader, 1963; Hope, 1966, 1969; Jennings, 1967; Powell, 1981, 1993).

  7. Measurement of Visual Reaction Times Using Hand-held Mobile Devices

    NASA Technical Reports Server (NTRS)

    Mulligan, Jeffrey B.; Arsintescu, Lucia; Flynn-Evans, Erin

    2015-01-01

    Modern mobile devices provide a convenient platform for collecting research data in the field. But,because the working of these devices is often cloaked behind multiple layers of proprietary system software, it can bedifficult to assess the accuracy of the data they produce, particularly in the case of timing. We have been collecting datain a simple visual reaction time experiment, as part of a fatigue testing protocol known as the Psychomotor Vigilance Test (PVT). In this protocol, subjects run a 5-minute block consisting of a sequence of trials in which a visual stimulus appears after an unpredictable variable delay. The subject is required to tap the screen as soon as possible after the appearance of the stimulus. In order to validate the reaction times reported by our program, we had subjects perform the task while a high-speed video camera recorded both the display screen, and a side view of the finger (observed in a mirror). Simple image-processing methods were applied to determine the frames in which the stimulus appeared and disappeared, and in which the finger made and broke contact with the screen. The results demonstrate a systematic delay between the initial contact by the finger and the detection of the touch by the software, having a value of 80 +- 20 milliseconds.

  8. SU-E-T-194: From Dicom-RT to Radiobiological Dose Metrics in 5 Minutes

    SciTech Connect

    Whelan, B; Holloway, L

    2014-06-01

    Purpose: To develop a flexible and standalone framework for batch calculation of radiobiological dose metrics from Dicom-RT. Methods: Software has been developed which allows (1) The calculation of DVH data from DICOM dose and structure files (DVHgenerator), (2) Calculation of a wide range of radiobiological metrics from this data (CompPlanGui). Both these tools are run via graphical user interface (GUI), making them fast and simple. Part 1 is a new tool which has not previously been published, whilst part 2 is a GUI overlay for the previously published software ‘Comp-Plan’ (Holloway et. al., Medical Dosimetry, 2012), previously reliant on command line interface. The time taken for an experienced user to evaluate a test case of 6 plans with and without CompPlanGUI was quantified. Results: The DVH-generator has been found to be faster, more robust and require far less physical memory then using alternative software solutions for the same purpose. The Comp Plan GUI significantly reduces the amount of time required to set up a base directory, eliminates code crashes arising from typographical errors, and renders the code far more accessible to non-expert users. It took an experienced user of the code around 3 minutes to set up a base directory of 6 plans compared around 8 minutes without, indicating that using CompPlanGUI reduced setup time by over 50%. Conclusion: A standalone GUI based framework has developed which allows for the batch calculation of radiobiological dose metrics directly from Dicom-RT files. As with the original code, this work will be made freely available on request, as well as via matlab file exchange.

  9. No Evidence of Reaction Time Slowing in Autism Spectrum Disorder

    ERIC Educational Resources Information Center

    Ferraro, F. Richard

    2016-01-01

    A total of 32 studies comprising 238 simple reaction time and choice reaction time conditions were examined in individuals with autism spectrum disorder (n?=?964) and controls (n?=?1032). A Brinley plot/multiple regression analysis was performed on mean reaction times, regressing autism spectrum disorder performance onto the control performance as…

  10. Effect of Reaction Developing Training on Audio-Visual Feet Reaction Time in Wrestlers

    ERIC Educational Resources Information Center

    Kaya, Mustafa

    2016-01-01

    Reaction time is one of the most determinative elements for a successful sports performance. The purpose of this study was to investigate the effect of 12-week feet reaction developing trainings upon feet reaction time of females at 11-13 age interval. Volunteer sportsmen between 11 and 13 age interval who were active in Tokat Provincial…

  11. Extreme reaction times determine fluctuation scaling in human color vision

    NASA Astrophysics Data System (ADS)

    Medina, José M.; Díaz, José A.

    2016-11-01

    In modern mental chronometry, human reaction time defines the time elapsed from stimulus presentation until a response occurs and represents a reference paradigm for investigating stochastic latency mechanisms in color vision. Here we examine the statistical properties of extreme reaction times and whether they support fluctuation scaling in the skewness-kurtosis plane. Reaction times were measured for visual stimuli across the cardinal directions of the color space. For all subjects, the results show that very large reaction times deviate from the right tail of reaction time distributions suggesting the existence of dragon-kings events. The results also indicate that extreme reaction times are correlated and shape fluctuation scaling over a wide range of stimulus conditions. The scaling exponent was higher for achromatic than isoluminant stimuli, suggesting distinct generative mechanisms. Our findings open a new perspective for studying failure modes in sensory-motor communications and in complex networks.

  12. The effect of ethanol sclerotherapy of 5 minutes duration on cyst diameter and rat ovarian tissue in simple ovarian cysts

    PubMed Central

    Şimşek, Mehmet; Kuloğlu, Tuncay; Pala, Şehmus; Boztosun, Abdullah; Can, Behzat; Atilgan, Remzi

    2015-01-01

    Objectives To examine the effect of 95% ethanol sclerotherapy (EST) administered over 5 minutes on cyst diameter and ovarian tissue in experimentally induced simple ovarian cysts in a rat model. Materials and methods In order to induce ovarian cysts, unilateral total salpingectomy was performed in regularly menstruating adult female Wistar albino rats (n=20) between 12 and 14 weeks of age and weighing between 200 and 220 g. One month after the procedure, the abdominal cavity was opened and 14 rats (70%) were found to have developed macroscopic cysts. Rats with macroscopic cysts (n=14) were assigned into two groups in a prospective and single-blinded manner: group 1 (G1) (n=7), control rats; and group 2 (G2) (n=7), 5-minute EST 95% group. Cyst diameter was measured and recorded for each rat. In G2, after whole cyst fluid was aspirated the cystic cavity was irrigated with 95% ethanol, approximately equal to half of the aspirated cyst volume, after which an interval of 5 minutes was allowed and same amount was re-aspirated and the abdominal cavity was closed. One month after this procedure, abdominal cavities were reopened and intra-abdominal adhesion scoring was performed in both groups. Cyst diameter was measured for each rat, and the right ovary was removed, fixed in 10% formaldehyde, and transported to the laboratory. A histologic assessment of the ovarian tissues was performed under light microscopy following staining with hematoxylin and eosin. Mann–Whitney U-test was used for statistical analysis. A P-level less than 0.05 was considered significant. Results In comparison with G1, there was a statistically significant reduction in the mean ovarian cyst dimensions in G2, while there were no significant differences between the two groups with respect to total number of follicles. Again, a significant increase in apoptotic activity and germinal epithelial degeneration was observed in G2 as compared to G1. The two groups were similar in terms of adhesion formation

  13. Sprint starts and the minimum auditory reaction time.

    PubMed

    Pain, Matthew T G; Hibbs, Angela

    2007-01-01

    The simple auditory reaction time is one of the fastest reaction times and is thought to be rarely less than 100 ms. The current false start criterion in a sprint used by the International Association of Athletics Federations is based on this assumed auditory reaction time of 100 ms. However, there is evidence, both anecdotal and from reflex research, that simple auditory reaction times of less than 100 ms can be achieved. Reaction time in nine athletes performing sprint starts in four conditions was measured using starting blocks instrumented with piezoelectric force transducers in each footplate that were synchronized with the starting signal. Only three conditions were used to calculate reaction times. The pre-motor and pseudo-motor time for two athletes were also measured across 13 muscles using surface electromyography (EMG) synchronized with the rest of the system. Five of the athletes had mean reaction times of less than 100 ms in at least one condition and 20% of all starts in the first two conditions had a reaction time of less than 100 ms. The results demonstrate that the neuromuscular-physiological component of simple auditory reaction times can be under 85 ms and that EMG latencies can be under 60 ms. PMID:17127583

  14. Reading and a diffusion model analysis of reaction time.

    PubMed

    Naples, Adam; Katz, Leonard; Grigorenko, Elena L

    2012-01-01

    Processing speed is associated with reading performance. However, the literature is not clear either on the definition of processing speed or on why and how it contributes to reading performance. In this study we demonstrated that processing speed, as measured by reaction time, is not a unitary construct. Using the diffusion model of two-choice reaction time, we assessed processing speed in a series of same-different reaction time tasks for letter and number strings. We demonstrated that the association between reaction time and reading performance is driven by processing speed for reading-related information, but not motor or sensory encoding speed.

  15. No evidence of reaction time slowing in autism spectrum disorder.

    PubMed

    Ferraro, F Richard

    2016-01-01

    A total of 32 studies comprising 238 simple reaction time and choice reaction time conditions were examined in individuals with autism spectrum disorder (n = 964) and controls (n = 1032). A Brinley plot/multiple regression analysis was performed on mean reaction times, regressing autism spectrum disorder performance onto the control performance as a way to examine any generalized simple reaction time/choice reaction time slowing exhibited by the autism spectrum disorder group. The resulting regression equation was Y (autism spectrum disorder) = 0.99 × (control) + 87.93, which accounted for 92.3% of the variance. These results suggest that there are little if any simple reaction time/choice reaction time slowing in this sample of individual with autism spectrum disorder, in comparison with controls. While many cognitive and information processing domains are compromised in autism spectrum disorder, it appears that simple reaction time/choice reaction time remain relatively unaffected in autism spectrum disorder.

  16. Reading and a Diffusion Model Analysis of Reaction Time

    PubMed Central

    Naples, Adam; Katz, Leonard; Grigorenko, Elena L.

    2012-01-01

    Processing speed is associated with reading performance. However, the literature is not clear either on the definition of processing speed or on why and how it contributes to reading performance. In this study we demonstrated that processing speed, as measured by reaction time, is not a unitary construct. Using the diffusion model of two-choice reaction time, we assessed processing speed in a series of same-different reaction time tasks for letter and number strings. We demonstrated that the association between reaction time and reading performance is driven by processing speed for reading-related information, but not motor or sensory encoding speed. PMID:22612543

  17. Noise-induced transition in human reaction times

    NASA Astrophysics Data System (ADS)

    Medina, José M.; Díaz, José A.

    2016-09-01

    The human reaction/response time can be defined as the time elapsed from the onset of stimulus presentation until a response occurs in many sensory and cognitive processes. A reaction time model based on Piéron’s law is investigated. The model shows a noise-induced transition in the moments of reaction time distributions due to the presence of strong additive noise. The model also demonstrates that reaction times do not follow fluctuation scaling between the mean and the variance but follow a generalized version between the skewness and the kurtosis. The results indicate that noise-induced transitions in the moments govern fluctuations in sensory-motor transformations and open an insight into the macroscopic effects of noise in human perception and action. The conditions that lead to extreme reaction times are discussed based on the transfer of information in neurons.

  18. Reaction Time of a Group of Physics Students

    ERIC Educational Resources Information Center

    Saxena, Charu; Kaur, Rini; Arun, P.

    2008-01-01

    The reaction time of a group of students majoring in physics is reported here. Strong correlation between fatigue, reaction time and performance has been observed and may be useful for academicians and administrators responsible for working out timetables, course structures, student counsellings, etc. (Contains 5 figures, 1 table, and 1 footnote.)

  19. Intelligence, Reaction Times, and Peripheral Nerve Conduction Velocity.

    ERIC Educational Resources Information Center

    Vernon, Philip A.; Mori, Monica

    1992-01-01

    In 2 studies with 85 and 88 undergraduates, respectively, peripheral nerve conduction velocity (NCV) was significantly correlated with IQ score and reaction times, and NCV and reaction time contributed significantly, in combination, to prediction of IQ. Results are interpreted in terms of a neural efficiency model of intelligence. (Author/SLD)

  20. Surficial and bedrock geologic map database of the Kelso 7.5 Minute quadrangle, San Bernardino County, California

    USGS Publications Warehouse

    Bedford, David R.

    2003-01-01

    This geologic map database describes geologic materials for the Kelso 7.5 Minute Quadrangle, San Bernardino County, California. The area lies in eastern Mojave Desert of California, within the Mojave National Preserve (a unit of the National Parks system). Geologic deposits in the area consist of Proterozoic metamorphic rocks, Cambrian-Neoproterozoic sedimentary rocks, Mesozoic plutonic and hypabyssal rocks, Tertiary basin fill, and Quaternary surficial deposits. Bedrock deposits are described by composition, texture, and stratigraphic relationships. Quaternary surficial deposits are classified into soil-geomorphic surfaces based on soil characteristics, inset relationships, and geomorphic expression. The surficial geology presented in this report is especially useful to understand, and extrapolate, physical properties that influence surface conditions, and surface- and soil-water dynamics. Physical characteristics such as pavement development, soil horizonation, and hydraulic characteristics have shown to be some of the primary drivers of ecologic dynamics, including recovery of those ecosystems to anthropogenic disturbance, in the eastern Mojave Desert and other arid and semi-arid environments.

  1. Time dependence of the reaction of water with glass

    SciTech Connect

    Doremus, R.H.

    1980-01-01

    Equations for the time-dependence of release of constituents from glass during reaction with water are discussed. Values of linear dissolution rates of different glasses are compared. Models for the reaction of water with glass are discussed. It is concluded that extrapolation of constant dissolution rates for durable glasses such as commercial soda-limes is reliable, but such extrapolation for borosilicate glass for waste disposal is less reliable because the mechanisms involved in their reaction with water are unclear. 25 refs.

  2. A complex reaction time study (Sternberg) in space flight

    NASA Technical Reports Server (NTRS)

    Thornton, W.; Uri, John; Moore, Tom

    1993-01-01

    Simple and complex (Sternberg) reaction time studies were flown on three and seven day Shuttle flights in 1985. Three subjects did selftesting with an onboard handheld calculator without difficulty. There was little change in simple reaction time. One subject demonstrated a decrease in the processing rate during space motion sickness while a second exhibited an increase in complex reaction time without a change in processing rate during a period of high work load. The population was too small to demonstrate significant changes. This study demonstrates the ease and practicality of such measurements and indicates the potential value of such studies in space.

  3. Iris Pigmentation and Fractionated Reaction and Reflex Time.

    ERIC Educational Resources Information Center

    Hale, Bruce D.; And Others

    Behavioral measures, fractionated reaction and reflex times by means of electromyography, were used to determine if the eye color differences are found in the central or peripheral regions of the nervous system. The purpose of this research was to determine the truth of the hypothesis that dark-eyed individuals have faster reflex and reaction time…

  4. Geologic map of the Scotts Mills, Silverton, and Stayton Northeast 7.5 minute quadrangles, Northwest Oregon: a digital database

    USGS Publications Warehouse

    Tolan, Terry; Beeson, Marvin; Wheeler, Karen L.

    1999-01-01

    The Scotts Mills, Silverton, and Stayton NE 7.5 minute quadrangles are situated along the eastern margin of the Willamette Valley and adjacent lower foothills (Waldo and Silverton Hills) of the Cascade Range (Fig. 1). The terrain within this area is of low to moderate relief, ranging from 100 to more than 1000 ft above sea level. This area is largely rural, with most of the valley floor and low-relief foothills under cultivation. In the last decade, the rural areas outside the boundaries of established towns have experienced significant growth in new homes built and the expansion of housing subdivisions. This growth has placed an increased demand on existing geologic resources (e.g., groundwater, sand and gravel, crushed stone) and the need to better understand potential geologic hazards within this region. Previous geologic mapping by Piper (1942), Peck and others (1964), Newton (1969), Hampton (1972), Miller and Orr (1984), Orr and Miller (1984), and Miller and Orr (1986, 1988) established and refined the general stratigraphic framework of this region. This mapping identified few faults or folds; earlier investigators were hindered by the lack of reliably identifiable marker horizons within the stratigraphic section. Werner (1991), using available seismic profile lines and well data in the Willamette Valley to locate the top of the Columbia River Basalt Group, was able to identify and map faults within the subsurface. Reconnaissance mapping of the Columbia River Basalt Group (CRBG) units in this region in the early 1980’s indicated that these stratigraphic units could serve as a series of unique reference horizons for identifying post-Miocene folding and faulting (Beeson and others, 1985, 1989; Beeson and Tolan, 1990). The major emphasis of this investigation was to identify and map CRBG units within the Scotts Mills, Silverton, and Stayton NE quadrangles and to utilize this detailed CRBG stratigraphy to identify and characterize structural features.

  5. The Effect of Road Traffic Noise on Reaction Time

    PubMed Central

    Alimohammadi, Iraj; Zokaei, Mojtaba; Sandrock, Stephan

    2015-01-01

    Background: Traffic noise is one of the main important sources in urban noise pollution, which causes various physiological and psychological effects that can cause disturbs in performance, sleep disturbances, hearing loss and impact on job performance. This study was conducted to verify the impact of road traffic noise on reaction time in terms of extraversion and sex. Methods: Traffic noise was measured and recorded in 10 arterial streets in Tehran, and then the recorded noise was emitted towards participants in an acoustic room. The participants were 80 (40 cases and 40 controls) students. Personality type was determined by Eysenck Personality Inventory (EPI) questioner. Reaction time before and after exposure to traffic noise was measured. Results: Reaction time before exposure to traffic noise did not differ (P=0.437) significantly between introverts and extraverts. However, it was increased significantly in both groups after exposure to traffic noise (P<0.01). Introvert’s reaction time was more increased than that of extraverts. Conclusion: Traffic noise augmented reaction time of both males and females. This study also revealed that exposure to traffic noise leads to increase in reaction time. PMID:26634199

  6. Imaginary-time formalism for triple-α reaction rates

    NASA Astrophysics Data System (ADS)

    Akahori, T.; Funaki, Y.; Yabana, K.

    2015-08-01

    Using imaginary-time formalism, it is shown that the triple-α reaction rate can be reliably calculated without the need to solve scattering problems involving three charged particles. The calculated reaction rate is found to agree well with the empirical NACRE rate, which is widely adopted in stellar evolution calculations. The reason for this is explained using R -matrix theory. Extremely slow convergence is found to occur when a coupled-channel expansion is introduced, which helps to explain the very different reaction rates obtained using a coupled-channel approach.

  7. Quantification of reaction time and time perception during Space Shuttle operations

    NASA Technical Reports Server (NTRS)

    Ratino, D. A.; Repperger, D. W.; Goodyear, C.; Potor, G.; Rodriguez, L. E.

    1988-01-01

    A microprocessor-based test battery containing simple reaction time, choice reaction time, and time perception tasks was flown aboard a 1985 Space Shuttle flight. Data were obtained from four crew members. Individual subject means indicate a correlation between change in reaction time during the flight and the presence of space motion sickness symptoms. The time perception task results indicate that the shortest duration task time (2 s) is progressively overestimated as the mission proceeds and is statistically significant when comparing preflight and postflight baselines. The tasks that required longer periods of time to estimate (8, 12, and 16 s) are less affected.

  8. Effect of Puberty on Reaction and Movement Times

    ERIC Educational Resources Information Center

    Fulton, Clifton D.; Hubbard, Alfred W.

    1975-01-01

    Reaction times, movement times, and static strengths of the four limbs were measured and pubertal status was assessed in males and females at ages nine, 11, 13, 15, and 17 years primarily to separate the effects of sexual maturation from the associated sex and age trends. (RC)

  9. Geologic map and digital database of the Conejo Well 7.5 minute quadrangle, Riverside County, Southern California

    USGS Publications Warehouse

    Powell, Robert E.

    2001-01-01

    This data set maps and describes the geology of the Conejo Well 7.5 minute quadrangle, Riverside County, southern California. The quadrangle, situated in Joshua Tree National Park in the eastern Transverse Ranges physiographic and structural province, encompasses part of the northern Eagle Mountains and part of the south flank of Pinto Basin. It is underlain by a basement terrane comprising Proterozoic metamorphic rocks, Mesozoic plutonic rocks, and Mesozoic and Mesozoic or Cenozoic hypabyssal dikes. The basement terrane is capped by a widespread Tertiary erosion surface preserved in remnants in the Eagle Mountains and buried beneath Cenozoic deposits in Pinto Basin. Locally, Miocene basalt overlies the erosion surface. A sequence of at least three Quaternary pediments is planed into the north piedmont of the Eagle Mountains, each in turn overlain by successively younger residual and alluvial deposits. The Tertiary erosion surface is deformed and broken by north-northwest-trending, high-angle, dip-slip faults in the Eagle Mountains and an east-west trending system of high-angle dip- and left-slip faults. In and adjacent to the Conejo Well quadrangle, faults of the northwest-trending set displace Miocene sedimentary rocks and basalt deposited on the Tertiary erosion surface and Pliocene and (or) Pleistocene deposits that accumulated on the oldest pediment. Faults of this system appear to be overlain by Pleistocene deposits that accumulated on younger pediments. East-west trending faults are younger than and perhaps in part coeval with faults of the northwest-trending set. The Conejo Well database was created using ARCVIEW and ARC/INFO, which are geographical information system (GIS) software products of Envronmental Systems Research Institute (ESRI). The database consists of the following items: (1) a map coverage showing faults and geologic contacts and units, (2) a separate coverage showing dikes, (3) a coverage showing structural data, (4) a point coverage

  10. Geologic map and digital database of the Porcupine Wash 7.5 minute Quadrangle, Riverside County, southern California

    USGS Publications Warehouse

    Powell, Robert E.

    2001-01-01

    This data set maps and describes the geology of the Porcupine Wash 7.5 minute quadrangle, Riverside County, southern California. The quadrangle, situated in Joshua Tree National Park in the eastern Transverse Ranges physiographic and structural province, encompasses parts of the Hexie Mountains, Cottonwood Mountains, northern Eagle Mountains, and south flank of Pinto Basin. It is underlain by a basement terrane comprising Proterozoic metamorphic rocks, Mesozoic plutonic rocks, and Mesozoic and Mesozoic or Cenozoic hypabyssal dikes. The basement terrane is capped by a widespread Tertiary erosion surface preserved in remnants in the Eagle and Cottonwood Mountains and buried beneath Cenozoic deposits in Pinto Basin. Locally, Miocene basalt overlies the erosion surface. A sequence of at least three Quaternary pediments is planed into the north piedmont of the Eagle and Hexie Mountains, each in turn overlain by successively younger residual and alluvial deposits. The Tertiary erosion surface is deformed and broken by north-northwest-trending, high-angle, dip-slip faults and an east-west trending system of high-angle dip- and left-slip faults. East-west trending faults are younger than and perhaps in part coeval with faults of the northwest-trending set. The Porcupine Wash database was created using ARCVIEW and ARC/INFO, which are geographical information system (GIS) software products of Envronmental Systems Research Institute (ESRI). The database consists of the following items: (1) a map coverage showing faults and geologic contacts and units, (2) a separate coverage showing dikes, (3) a coverage showing structural data, (4) a scanned topographic base at a scale of 1:24,000, and (5) attribute tables for geologic units (polygons and regions), contacts (arcs), and site-specific data (points). The database, accompanied by a pamphlet file and this metadata file, also includes the following graphic and text products: (1) A portable document file (.pdf) containing a

  11. Gustatory reaction time to various sweeteners in human adults.

    PubMed

    Yamamoto, T; Kato, T; Matsuo, R; Kawamura, Y; Yoshida, M

    1985-09-01

    Reaction times to recognize the sweet taste of 12 sweeteners at various concentrations were measured in 48 human adults. The reaction time (T) decreased with increasing concentration (C) of each sweetener applied to the anterior dorsal tongue. The relationships between T and C, and T and logC were well described by a rectangular hyperbola formula for each of the 12 sweeteners. Reaction times to discriminate sweet taste quality between pairs of sweeteners were measured, then a similarity index was calculated. Factor analysis based on correlation coefficients between pairs of sweeteners which were obtained by the similarity indices has indicated classification of the sweeteners. Sucrose, fructose, glucose, maltose, sorbitol and aspartame tend to group together. Na-cyclamate and Na-saccharin form another group. DL-alanine, stevioside and neohesperidin dihydrochalcone are rather independent and do not belong to any group.

  12. Assessment of Driver's Reaction Times in Diverisified Research Environments

    NASA Astrophysics Data System (ADS)

    Guzek, Marek; Lozia, Zbigniew; Zdanowicz, Piotr; Jurecki, Rafał S.; Stańczyk, Tomasz L.; Pieniążek, Wiesław

    2012-06-01

    Reaction time is one of the basic parameters that characterize the driver and very important in the analysis of accident situations in road traffic. This paper describes research studies on the reaction time evaluation as conducted in three environments: on a typical device used in the transport psychology labs (the so-called reflexometer), in the driving simulator (autoPW) and on the driving test track (the Kielce Test Track). In all environments, the tests were performed for the same group of drivers. The article presents the characteristics of research in each environment as well as shows and compares exemplary results.

  13. Numbers or apologies? Customer reactions to telephone waiting time fillers.

    PubMed

    Munichor, Nira; Rafaeli, Anat

    2007-03-01

    The authors examined the effect of time perception and sense of progress in telephone queues on caller reactions to 3 telephone waiting time fillers: music, apologies, and information about location in the queue. In Study 1, conducted on 123 real calls, call abandonment was lowest, and call evaluations were most positive with information about location in the queue as the time filler. In Study 2, conducted with 83 participants who experienced a simulated telephone wait experience, sense of progress in the queue rather than perceived waiting time mediated the relationship between telephone waiting time filler and caller reactions. The findings provide insight for the management and design of telephone queues, as well as theoretical insight into critical cognitive processes that underlie telephone waiting, opening up an important new research agenda. PMID:17371095

  14. Correction for instrument time constant in determination of reaction kinetics.

    SciTech Connect

    Chilton, Marie; Clark, Jared; Thomas, Nathan; Nicholson, Allen; Hansen, Lee D.; Hansen, Clifford W.; Hansen, Jaron

    2010-02-01

    Rates of reactions can be expressed as dn/dt = kcf(n) where n is moles of reaction, k is a rate constant, c is a proportionality constant, and f(n) is a function of the properties of the sample. When the instrument time constant, ?, and k are sufficiently comparable that measured rates are significantly affected by instrument response, correction for instrument response must be done to obtain accurate reaction kinetics. Correction for instrument response has previously been done by truncating early data or by use of the Tian equation. Both methods can lead to significant errors. We describe a method for simultaneous determination of ?, k, and c by fitting equations describing the combined instrument response and rate law to rates observed as a function of time. The method was tested with data on the heat rate from acid-catalyzed hydrolysis of sucrose.

  15. Choice (CRT) and simple reaction times (SRT) compared in laboratory technicians: Factors influencing reaction times and a predictive model

    SciTech Connect

    Miller, J.A.; Cohen, G.S.; Warshaw, R.; Thornton, J.C.; Kilburn, K.H.

    1989-01-01

    Choice reaction time (CRT) and simple reaction time (SRT) tests were administered to 151 female histology laboratory technicians to determine if occupational exposure to organic solvents and formaldehyde delayed either or both. The relationships between CRT and SRT latencies were evaluated using different testers, sequences of administration, and microcomputers. Formaldehyde exposure, cigarette smoking history, ethnicity, and alveolar CO levels did not significantly influence CRT and SRT. However, slightly different protocols did significantly affect SRT. A linear model demonstrated that logSRT (LSRT) and LogCRT (LCRT) were longer with increasing age, promising further clinical applications. It is concluded that both CRT and SRT measure some overlapping and some different neurologic pathways. Reaction times in large ''normal'' populations are needed to compare with groups exposed to potential neurotoxins.

  16. Reaction schemes, escape times and geminate recombinations in particle-based spatial simulations of biochemical reactions

    NASA Astrophysics Data System (ADS)

    Klann, Michael; Koeppl, Heinz

    2013-08-01

    Modeling the spatiotemporal dynamics of biochemical reaction systems at single-molecule resolution has become feasible with the increase of computing power and is applied especially to cellular signal transduction. For an association reaction the two molecules have to be in contact. Hence, a physically faithful model of the molecular interaction assumes non-overlapping molecules that interact at their surfaces (boundary scheme). For performance reasons, this model can be replaced by particles that can overlap and react when they are closer than a certain distance with a reaction probability (volume scheme). Here we present an analytical approximation for the reaction probability in the volume scheme and compare the volume- with the boundary scheme. A dissociation reaction, in contrast, creates two molecules next to each other. If the reaction is reversible, these two products can directly re-bind again, leading to an overestimation of the dimerized state in the simulation. We show how the correct recombination rate can be achieved if the products of the dissociation are placed at identical positions, but cannot react for a certain timespan. This refractory time corresponds to the completion of the diffusion-controlled dissociation of the two molecules to their contact distance ri + rj at t = \\hat{\\tau }\\times (r_i+r_j)^2/(D_i+D_j) with \\hat{\\tau }= 1/10 for molecules with radii ri and rj and diffusion coefficients Di and Dj, respectively.

  17. Force, reaction time, and precision of Kung Fu strikes.

    PubMed

    Neto, Osmar Pinto; Bolander, Richard; Pacheco, Marcos Tadeu Tavares; Bir, Cynthia

    2009-08-01

    The goal was to compare values of force, precision, and reaction time of several martial arts punches and palm strikes performed by advanced and intermediate Kung Fu practitioners, both men and women. 13 Kung Fu practitioners, 10 men and three women, participated. Only the men, three advanced and seven intermediate, were considered for comparisons between levels. Reaction time values were obtained using two high speed cameras that recorded each strike at 2500 Hz. Force of impact was measured by a load cell. For comparisons of groups, force data were normalized by participant's body mass and height. Precision of the strikes was determined by a high speed pressure sensor. The results show that palm strikes were stronger than punches. Women in the study presented, on average, lower values of reaction time and force but higher values of precision than men. Advanced participants presented higher forces than intermediate participants. Significant negative correlations between the values of force and precision and the values of force and reaction time were also found.

  18. Is Reaction Time Variability in ADHD Mainly at Low Frequencies?

    ERIC Educational Resources Information Center

    Karalunas, Sarah L.; Huang-Pollock, Cynthia L.; Nigg, Joel T.

    2013-01-01

    Background: Intraindividual variability in reaction times (RT variability) has garnered increasing interest as an indicator of cognitive and neurobiological dysfunction in children with attention deficit hyperactivity disorder (ADHD). Recent theory and research has emphasized specific low-frequency patterns of RT variability. However, whether…

  19. Physiological Evidence for Response Inhibition in Choice Reaction Time Tasks

    ERIC Educational Resources Information Center

    Burle, Boris; Vidal, Frank; Tandonnet, Christophe; Hasbroucq, Thierry

    2004-01-01

    Inhibition is a widely used notion proposed to account for data obtained in choice reaction time (RT) tasks. However, this concept is weakly supported by empirical facts. In this paper, we review a series of experiments using Hoffman reflex, transcranial magnetic stimulation and electroencephalography to study inhibition in choice RT tasks. We…

  20. Reaction Time, Intelligence and Learning Curve: An Exploratory Investigation.

    ERIC Educational Resources Information Center

    Boretz, Harold F.; And Others

    Previous studies indicate increasing, significant univariate and multivariate correlation between reaction time (RT) tasks and intelligence. Using multiple regression analyses, data from an earlier study by Brown and Boretz were reanalyzed to further investigate the relationship between the speed at which an individual is able to process stimuli…

  1. Digital, labial, and velopharyngeal reaction times in normal speakers.

    PubMed

    Dalston, R M; Keefe, M J

    1988-07-01

    The relationship between inherent speed limitations of the velopharyngeal mechanism and the observed phenomenon of assimilation nasality was investigated by studying the reaction times of 10 normal adults performing three movements: (1) lip closing, (2) velopharyngeal closing, and (3) pressing a response key with a finger. The first two movements were monitored using a photodetector system. Across nearly 300 responses for each of the motor responses, the average reaction times, in milliseconds, were 194 for the digital, 203 for the labial, and 206 for the velopharyngeal movements. An analysis of variance revealed no consistent differences among these responses. The significance of these data is discussed with respect to speech motor control and clinical evaluation of patients with velopharyngeal impairments.

  2. Repeated cryostimulation improves position sense and simple reaction time

    PubMed Central

    Giemza, Czesław; Bieć, Ewa; Ostrowska, Bożena; Piechaczek, Bogusława; Sitny, Georg; Kuczyński, Michał

    2016-01-01

    [Purpose] Whole body cryotherapy has been shown to have many benefits, yet nothing is known if and how this modality can improve neuromuscular performance and retain those improvements. [Subjects and Methods] Joint position sense based on the bilateral knee joint matching test and simple reaction time was investigated in 25 young healthy adults who underwent an extended period of whole body cryostimulation. The measurements were taken at baseline and after 10, 20, and 30 whole body cryotherapy sessions, with three days elapsing after the last treatment, and comparing the results with 24 control subjects. [Results] Only when 20 sessions were completed did joint position sense and simple reaction time improve in the intervention group. After 30 sessions, the outcome was similar. Equal results were found at baseline and after 10 sessions in both groups, but the intervention group outstripped controls after 20 and 30 sessions in both joint position sense and simple reaction time. [Conclusion] These results indicate that the common standard of 10 sessions is insufficient, while approximately 20 sessions of whole body cryotherapy may efficiently enhance neuromuscular performance with an ability to sustain the effects for at least three days. PMID:27313369

  3. Primary reactions in photosynthetic reaction centers of Rhodobacter sphaeroides - Time constants of the initial electron transfer

    NASA Astrophysics Data System (ADS)

    Dominguez, Pablo Nahuel; Himmelstoss, Matthias; Michelmann, Jeff; Lehner, Florian Thomas; Gardiner, Alastair T.; Cogdell, Richard J.; Zinth, Wolfgang

    2014-05-01

    The primary dynamics of reaction centers from Rhodobacter sphaeroides at room temperature are studied at low excitation intensities and low excitation rates. Analysis based on singular value decomposition yields three time constants in the picosecond range (ca. 1.2 ps, 3.5 ps and 220 ps). The spectral and temporal signatures are fully consistent with the step-wise electron transfer model published previously, with a first electron transfer to the bacteriochlorophyll with a time constant of 3.5 ps and a second 1.2 ps transfer to the bacteriopheophytin. No indications for adiabatic electron transfer are found in the time range >0.5 ps.

  4. Effect of reaction time on the formation of disinfection byproducts

    USGS Publications Warehouse

    Rathbun, R.E.

    1997-01-01

    The effect of reaction time on the trihalomethane and nonpurgeable total organic-halide formation potentials was determined by chlorinating water samples from the Mississippi, Missouri, and Ohio Rivers. Samples were collected for three seasons at 12 locations on the Mississippi from Minneapolis, Minnesota, to New Orleans, Louisiana, and on the Missouri and Ohio 1.6 kilometers above their confluences with the Mississippi. Both types of compounds formed rapidly during the initial stages of the reaction-time period, with formation rates decreasing with time. The ratio of the nonpurgeable total organic-halide and trihalomethane concentrations decreased with time, with the nonpurgeable total organic-halide compounds forming faster during the first stages of the time period and the trihalomethane compounds forming faster during the latter stages of the time period. Variation with distance along the Mississippi River of the formation rates approximately paralleled the variation of the dissolved organic carbon concentration, indicating that the rates of formation, as well as the concentrations of the compounds formed, depended on the dissolved organic carbon concentration.

  5. Time scales for molecule formation by ion-molecule reactions

    NASA Technical Reports Server (NTRS)

    Langer, W. D.; Glassgold, A. E.

    1976-01-01

    Analytical solutions are obtained for nonlinear differential equations governing the time-dependence of molecular abundances in interstellar clouds. Three gas-phase reaction schemes are considered separately for the regions where each dominates. The particular case of CO, and closely related members of the Oh and CH families of molecules, is studied for given values of temperature, density, and the radiation field. Nonlinear effects and couplings with particular ions are found to be important. The time scales for CO formation range from 100,000 to a few million years, depending on the chemistry and regime. The time required for essentially complete conversion of C(+) to CO in the region where the H3(+) chemistry dominates is several million years. Because this time is longer than or comparable to dynamical time scales for dense interstellar clouds, steady-state abundances may not be observed in such clouds.

  6. Perceived smoking availability differentially affects mood and reaction time

    PubMed Central

    Ross, Kathryn C.; Juliano, Laura M.

    2015-01-01

    Introduction This between subjects study explored the relationship between smoking availability and smoking motivation and is the first study to include three smoking availability time points. This allowed for an examination of an extended period of smoking unavailability, and a test of the linearity of the relationships between smoking availability and smoking motivation measures. Methods Ninety 3-hour abstinent smokers (mean ∼15 cigarettes per day) were randomly assigned to one of three availability manipulations while being exposed to smoking stimuli (i.e., pack of cigarettes): smoke in 20 min, smoke in 3 h, or smoke in 24 h. Participants completed pre- and post-manipulation measures of urge, positive affect and negative affect, and simple reaction time. Results The belief that smoking would next be available in 24 h resulted in a significant decrease in positive affect and increase in negative affect relative to the 3 h and 20 min conditions. A Lack of Fit test suggested a linear relationship between smoking availability and affect. A quadratic model appeared to be a better fit for the relationship between smoking availability and simple reaction time with participants in the 24 h and 20 min conditions showing a greater slowing of reaction time relative to the 3 h condition. There were no effects of the manipulations on self-reported urge, but baseline ceiling effects were noted. Conclusions Future investigations that manipulate three or more periods of time before smoking is available will help to better elucidate the nature of the relationship between smoking availability and smoking motivation. PMID:25727393

  7. On the continuum time limit of reaction-diffusion systems

    NASA Astrophysics Data System (ADS)

    Grassberger, Peter

    2013-09-01

    The parity-conserving branching-annihilating random walk (pc-BARW) model is a reaction-diffusion system on a lattice where particles can branch into m offsprings with even m and hop to neighboring sites. If two or more particles land on the same site, they immediately annihilate pairwise. In this way the number of particles is preserved modulo two. It is well known that the pc-BARW with m = 2 in 1 spatial dimension has no phase transition (it is always subcritical), if the hopping is described by a continuous time random walk. In contrast, the m = 2 1-d pc-BARW has a phase transition when formulated in discrete time, but we show that the continuous time limit is non-trivial: When the time step \\delta t\\to 0 , the branching and hopping probabilities at the critical point scale with different powers of \\delta t . These powers are different for different microscopic realizations. Although this phenomenon is not observed in some other reaction-diffusion systems like, e.g., the contact process, we argue that it should be generic and not restricted to the 1-d pc-BARW model.

  8. Reaction times to weak test lights. [psychophysics biological model

    NASA Technical Reports Server (NTRS)

    Wandell, B. A.; Ahumada, P.; Welsh, D.

    1984-01-01

    Maloney and Wandell (1984) describe a model of the response of a single visual channel to weak test lights. The initial channel response is a linearly filtered version of the stimulus. The filter output is randomly sampled over time. Each time a sample occurs there is some probability increasing with the magnitude of the sampled response - that a discrete detection event is generated. Maloney and Wandell derive the statistics of the detection events. In this paper a test is conducted of the hypothesis that the reaction time responses to the presence of a weak test light are initiated at the first detection event. This makes it possible to extend the application of the model to lights that are slightly above threshold, but still within the linear operating range of the visual system. A parameter-free prediction of the model proposed by Maloney and Wandell for lights detected by this statistic is tested. The data are in agreement with the prediction.

  9. Late visual and auditory ERP components and choice reaction time.

    PubMed

    Falkenstein, M; Hohnsbein, J; Hoormann, J

    1993-07-01

    Some relations between different late positive ERP components and choice reaction time (RT) were studied. In order to identify the different components we used visual and auditory stimuli, as well as simple and choice reaction tasks, since one of the components is thought to be modality dependent and the other one task dependent. In the paradigm the stimulus modalities were mixed, which was expected to lead to a maximum dissociation of the components after auditory stimuli (Hohnsbein et al. (1991). Electroencephalography and Clinical Neurophysiology, 78, 438-446). The results demonstrated the overlap of two positive waves in choice reaction tasks: a central one (P-SR), and a parietal one (P-CR). The latency of the P-SR varied greatly across modalities, but did not vary with RT, whereas the latency of the P-CR varied strongly with RT. The different overlap of these components on fast and slow trials caused amplitude and latency variations of the "P300" and the positive slow wave. Our results suggest a relation of the P-SR with stimulus evaluation (identification), and of the P-CR with response selection (stimulus-response mapping).

  10. Short relaxation times but long transient times in both simple and complex reaction networks

    PubMed Central

    Henry, Adrien; Martin, Olivier C.

    2016-01-01

    When relaxation towards an equilibrium or steady state is exponential at large times, one usually considers that the associated relaxation time τ, i.e. the inverse of the decay rate, is the longest characteristic time in the system. However, that need not be true, other times such as the lifetime of an infinitesimal perturbation can be much longer. In the present work, we demonstrate that this paradoxical property can arise even in quite simple systems such as a linear chain of reactions obeying mass action (MA) kinetics. By mathematical analysis of simple reaction networks, we pin-point the reason why the standard relaxation time does not provide relevant information on the potentially long transient times of typical infinitesimal perturbations. Overall, we consider four characteristic times and study their behaviour in both simple linear chains and in more complex reaction networks taken from the publicly available database ‘Biomodels’. In all these systems, whether involving MA rates, Michaelis–Menten reversible kinetics, or phenomenological laws for reaction rates, we find that the characteristic times corresponding to lifetimes of tracers and of concentration perturbations can be significantly longer than τ. PMID:27411726

  11. Equilibrium distributions of simple biochemical reaction systems for time-scale separation in stochastic reaction networks.

    PubMed

    Mélykúti, Bence; Hespanha, João P; Khammash, Mustafa

    2014-08-01

    Many biochemical reaction networks are inherently multiscale in time and in the counts of participating molecular species. A standard technique to treat different time scales in the stochastic kinetics framework is averaging or quasi-steady-state analysis: it is assumed that the fast dynamics reaches its equilibrium (stationary) distribution on a time scale where the slowly varying molecular counts are unlikely to have changed. We derive analytic equilibrium distributions for various simple biochemical systems, such as enzymatic reactions and gene regulation models. These can be directly inserted into simulations of the slow time-scale dynamics. They also provide insight into the stimulus-response of these systems. An important model for which we derive the analytic equilibrium distribution is the binding of dimer transcription factors (TFs) that first have to form from monomers. This gene regulation mechanism is compared to the cases of the binding of simple monomer TFs to one gene or to multiple copies of a gene, and to the cases of the cooperative binding of two or multiple TFs to a gene. The results apply equally to ligands binding to enzyme molecules.

  12. Equilibrium distributions of simple biochemical reaction systems for time-scale separation in stochastic reaction networks.

    PubMed

    Mélykúti, Bence; Hespanha, João P; Khammash, Mustafa

    2014-08-01

    Many biochemical reaction networks are inherently multiscale in time and in the counts of participating molecular species. A standard technique to treat different time scales in the stochastic kinetics framework is averaging or quasi-steady-state analysis: it is assumed that the fast dynamics reaches its equilibrium (stationary) distribution on a time scale where the slowly varying molecular counts are unlikely to have changed. We derive analytic equilibrium distributions for various simple biochemical systems, such as enzymatic reactions and gene regulation models. These can be directly inserted into simulations of the slow time-scale dynamics. They also provide insight into the stimulus-response of these systems. An important model for which we derive the analytic equilibrium distribution is the binding of dimer transcription factors (TFs) that first have to form from monomers. This gene regulation mechanism is compared to the cases of the binding of simple monomer TFs to one gene or to multiple copies of a gene, and to the cases of the cooperative binding of two or multiple TFs to a gene. The results apply equally to ligands binding to enzyme molecules. PMID:24920118

  13. Equilibrium distributions of simple biochemical reaction systems for time-scale separation in stochastic reaction networks

    PubMed Central

    Mélykúti, Bence; Hespanha, João P.; Khammash, Mustafa

    2014-01-01

    Many biochemical reaction networks are inherently multiscale in time and in the counts of participating molecular species. A standard technique to treat different time scales in the stochastic kinetics framework is averaging or quasi-steady-state analysis: it is assumed that the fast dynamics reaches its equilibrium (stationary) distribution on a time scale where the slowly varying molecular counts are unlikely to have changed. We derive analytic equilibrium distributions for various simple biochemical systems, such as enzymatic reactions and gene regulation models. These can be directly inserted into simulations of the slow time-scale dynamics. They also provide insight into the stimulus–response of these systems. An important model for which we derive the analytic equilibrium distribution is the binding of dimer transcription factors (TFs) that first have to form from monomers. This gene regulation mechanism is compared to the cases of the binding of simple monomer TFs to one gene or to multiple copies of a gene, and to the cases of the cooperative binding of two or multiple TFs to a gene. The results apply equally to ligands binding to enzyme molecules. PMID:24920118

  14. Acute Effects of Static and Dynamic Stretching on Balance, Agility, Reaction Time and Movement Time

    PubMed Central

    Chatzopoulos, Dimitris; Galazoulas, Christos; Patikas, Dimitrios; Kotzamanidis, Christos

    2014-01-01

    The purpose of this study was to compare the acute effects of three different stretching protocols on balance, agility, reaction time and movement time of the upper limbs. Participants were thirty one female high school athletes (age = 17.3 ± 0.5 yr.). All participants performed one of the following protocols on different days: (a) 3 min jogging followed by 7 min static stretching (SS), (b) 3 min jogging followed by 7 min dynamic stretching (DS), and (c) 3 min jogging followed by 7 min of rest (NS). After the protocols participants performed the following tests: dynamic balance, 505 agility test, reaction time (time between a sound stimulus and release of a button) and movement time (movement of the upper extremity over a 0.5 m distance). The order of stretching protocols and performance tests were counterbalanced to avoid carryover effects. Repeated measures analysis of variance revealed significant main effects for all variables except reaction time. The DS protocol compared to SS performed significantly better in balance, agility and movement time. Additionally, the DS protocol compared to NS performed significantly better in agility. According to the results of the study, a DS protocol is more appropriate than SS for activities that require balance, rapid change of running direction (agility) and movement time of the upper extremities. Key points Static stretching has a negative effect on balance and agility performance compared to dynamic stretching. There was no effect of the stretching protocols on reaction time. Dynamic stretching was more effective than static stretching for increasing movement time of the upper extremities. PMID:24790497

  15. Mediating millisecond reaction time around particles and cells.

    PubMed

    Dudani, Jaideep S; Go, Derek E; Gossett, Daniel R; Tan, Andrew P; Di Carlo, Dino

    2014-02-01

    Precise spatiotemporal control of how particles and cells interact with reagents is critical for numerous laboratory and industrial processes. Novel tools for exerting this control at shorter time scales will enable development of new chemical processes and biomedical assays. Previously, we have developed a generalized approach to manipulate cells and particles across fluid streams termed rapid inertial solution exchange (RInSE), which utilizes inertial lift forces at finite Reynolds number and high Peclet number to transfer particles from an initial solution to another within a millisecond. Here, we apply these principles toward developing a continuous flow microfluidic platform that enables transient chemical treatments of cells and particles (on the order of 1 ms). We also demonstrate how the reactant stream can be employed as a diffusion barrier, preventing adverse reactions between coflowing solutions. In order to demonstrate the utility of the method, we applied it to various operations in molecular biology and automated cell staining including cell permeabilization, fluorescent staining, and molecular delivery to viable cells. We expect this method will enable previously unexplored studies of the dynamics of molecular events, improve uniformity of reactions carried on the surface of beads, and increase uniformity in cell-based assays through automation.

  16. Reaction time as a measure of human associative learning.

    PubMed

    Craddock, Paul; Molet, Mikael; Miller, Ralph R

    2012-06-01

    Studies of human associative learning have often used causal/predictive learning preparations in which participants decide whether or not a first event is effective in causing or predicting a second event (i.e., an outcome). Those preparations have proved successful in replicating many Pavlovian phenomena. In the present paper we tested a novel associative learning preparation in which visually presented letters were paired with a visual outcome. Reaction times (RTs) were recorded to assess associative strength between specific cues and the outcome. Combining two different dependent variables (RTs and type of response given), we propose a rule for evaluating the associative strength between two events. The preparation and the data transformation rule were successful in producing several Pavlovian phenomena including excitatory acquisition, extinction, overshadowing, and latent inhibition, as well as established summation effects. Advantages and limitations of this new preparation based on the use of RT are discussed.

  17. Simple motor and phonemic processing reaction times of elderly subjects.

    PubMed

    Rastatter, M P; Hood, S B

    1986-07-01

    Simple motor reaction time (RT) was measured for arm movement in response to a known monosyllable presented by earphone. The required direction of movement (L or R) was known to S. Choice RT was also measured: only one word of a pair of taped monosyllabic words, differing only in the prevocalic consonant (e.g., tea-key) was presented by earphone. Simultaneously, a picture of each word appeared on response plates, one to the L and one to the R of the center rest position. S had to touch the response plate with the picture of the word heard. Subtracting simple from choice RT, in msec, yielded an estimate of auditory-phonemic processing (decoding) time. Data were collected from generally normal, healthy, elderly Ss [Grp I (10 M, 10 F) of 72 yrs mean age, and Grp II (7 M, 9 F) of 84 yrs mean age] and a control group (9 M, 9 F) of 21 yrs mean age. An ANOVA with repeated measures showed that significant differences existed among the 3 groups. A similar ANOVA procedure on phonemic processing time revealed that significant differences existed between the younger and the older Ss, but not between Grps I vs II. Collectively, these findings were taken to suggest that advanced age does not affect all behavioral operations in a generalized fashion. It was suggested that auditory-phonemic processing is more resistant to the aging process than manual responses. PMID:3680144

  18. Factors influencing the latency of simple reaction time

    PubMed Central

    Woods, David L.; Wyma, John M.; Yund, E. William; Herron, Timothy J.; Reed, Bruce

    2015-01-01

    Simple reaction time (SRT), the minimal time needed to respond to a stimulus, is a basic measure of processing speed. SRTs were first measured by Francis Galton in the 19th century, who reported visual SRT latencies below 190 ms in young subjects. However, recent large-scale studies have reported substantially increased SRT latencies that differ markedly in different laboratories, in part due to timing delays introduced by the computer hardware and software used for SRT measurement. We developed a calibrated and temporally precise SRT test to analyze the factors that influence SRT latencies in a paradigm where visual stimuli were presented to the left or right hemifield at varying stimulus onset asynchronies (SOAs). Experiment 1 examined a community sample of 1469 subjects ranging in age from 18 to 65. Mean SRT latencies were short (231, 213 ms when corrected for hardware delays) and increased significantly with age (0.55 ms/year), but were unaffected by sex or education. As in previous studies, SRTs were prolonged at shorter SOAs and were slightly faster for stimuli presented in the visual field contralateral to the responding hand. Stimulus detection time (SDT) was estimated by subtracting movement initiation time, measured in a speeded finger tapping test, from SRTs. SDT latencies averaged 131 ms and were unaffected by age. Experiment 2 tested 189 subjects ranging in age from 18 to 82 years in a different laboratory using a larger range of SOAs. Both SRTs and SDTs were slightly prolonged (by 7 ms). SRT latencies increased with age while SDT latencies remained stable. Precise computer-based measurements of SRT latencies show that processing speed is as fast in contemporary populations as in the Victorian era, and that age-related increases in SRT latencies are due primarily to slowed motor output. PMID:25859198

  19. Reaction time in ankle movements: a diffusion model analysis

    PubMed Central

    Michmizos, Konstantinos P.; Krebs, Hermano Igo

    2015-01-01

    Reaction time (RT) is one of the most commonly used measures of neurological function and dysfunction. Despite the extensive studies on it, no study has ever examined the RT in the ankle. Twenty-two subjects were recruited to perform simple, 2- and 4-choice RT tasks by visually guiding a cursor inside a rectangular target with their ankle. RT did not change with spatial accuracy constraints imposed by different target widths in the direction of the movement. RT increased as a linear function of potential target stimuli, as would be predicted by Hick–Hyman law. Although the slopes of the regressions were similar, the intercept in dorsal–plantar (DP) direction was significantly smaller than the intercept in inversion–eversion (IE) direction. To explain this difference, we used a hierarchical Bayesian estimation of the Ratcliff's (Psychol Rev 85:59, 1978) diffusion model parameters and divided processing time into cognitive components. The model gave a good account of RTs, their distribution and accuracy values, and hence provided a testimony that the non-decision processing time (overlap of posterior distributions between DP and IE < 0.045), the boundary separation (overlap of the posterior distributions < 0.1) and the evidence accumulation rate (overlap of the posterior distributions < 0.01) components of the RT accounted for the intercept difference between DP and IE. The model also proposed that there was no systematic change in non-decision processing time or drift rate when spatial accuracy constraints were altered. The results were in agreement with the memory drum hypothesis and could be further justified neurophysiologically by the larger innervation of the muscles controlling DP movements. This study might contribute to assessing deficits in sensorimotor control of the ankle and enlighten a possible target for correction in the framework of our on-going effort to develop robotic therapeutic interventions to the ankle of children with cerebral palsy

  20. Time-resolved multispectral imaging of combustion reaction

    NASA Astrophysics Data System (ADS)

    Huot, Alexandrine; Gagnon, Marc-André; Jahjah, Karl-Alexandre; Tremblay, Pierre; Savary, Simon; Farley, Vincent; Lagueux, Philippe; Guyot, Éric; Chamberland, Martin; Marcotte, Fréderick

    2015-05-01

    Thermal infrared imaging is a field of science that evolves rapidly. Scientists have used for years the simplest tool: thermal broadband cameras. This allows to perform target characterization in both the longwave (LWIR) and midwave (MWIR) infrared spectral range. Infrared thermal imaging is used for a wide range of applications, especially in the combustion domain. For example, it can be used to follow combustion reactions, in order to characterize the injection and the ignition in a combustion chamber or even to observe gases produced by a flare or smokestack. Most combustion gases such as carbon dioxide (CO2) selectively absorb/emit infrared radiation at discrete energies, i.e. over a very narrow spectral range. Therefore, temperatures derived from broadband imaging are not reliable without prior knowledge about spectral emissivity. This information is not directly available from broadband images. However, spectral information is available using spectral filters. In this work, combustion analysis was carried out using Telops MS-IR MW camera which allows multispectral imaging at a high frame rate. A motorized filter wheel allowing synchronized acquisitions on eight (8) different channels was used to provide time-resolved multispectral imaging of combustion products of a candle in which black powder has been burnt to create a burst. It was then possible to estimate the temperature by modeling spectral profile derived from information obtained with the different spectral filters. Comparison with temperatures obtained using conventional broadband imaging illustrates the benefits of time-resolved multispectral imaging for the characterization of combustion processes.

  1. Time-resolved multispectral imaging of combustion reactions

    NASA Astrophysics Data System (ADS)

    Huot, Alexandrine; Gagnon, Marc-André; Jahjah, Karl-Alexandre; Tremblay, Pierre; Savary, Simon; Farley, Vincent; Lagueux, Philippe; Guyot, Éric; Chamberland, Martin; Marcotte, Frédérick

    2015-10-01

    Thermal infrared imaging is a field of science that evolves rapidly. Scientists have used for years the simplest tool: thermal broadband cameras. These allow to perform target characterization in both the longwave (LWIR) and midwave (MWIR) infrared spectral range. Infrared thermal imaging is used for a wide range of applications, especially in the combustion domain. For example, it can be used to follow combustion reactions, in order to characterize the injection and the ignition in a combustion chamber or even to observe gases produced by a flare or smokestack. Most combustion gases, such as carbon dioxide (CO2), selectively absorb/emit infrared radiation at discrete energies, i.e. over a very narrow spectral range. Therefore, temperatures derived from broadband imaging are not reliable without prior knowledge of spectral emissivity. This information is not directly available from broadband images. However, spectral information is available using spectral filters. In this work, combustion analysis was carried out using a Telops MS-IR MW camera, which allows multispectral imaging at a high frame rate. A motorized filter wheel allowing synchronized acquisitions on eight (8) different channels was used to provide time-resolved multispectral imaging of combustion products of a candle in which black powder has been burnt to create a burst. It was then possible to estimate the temperature by modeling spectral profiles derived from information obtained with the different spectral filters. Comparison with temperatures obtained using conventional broadband imaging illustrates the benefits of time-resolved multispectral imaging for the characterization of combustion processes.

  2. Do ELF magnetic fields affect human reaction time?

    SciTech Connect

    Podd, J.V.; Whittington, C.J.; Barnes, G.R.G.; Page, W.H.; Rapley, B.I.

    1995-12-01

    Two double-blind studies were run in an attempt to confirm the finding that a 0.2 Hz magnetic field affects simple reaction time (RT) in humans, whereas a 0.1 Hz field does not. In the first experiment, 12 volunteer subjects were exposed to a continuous 0.2 Hz, 0.1 Hz, or sham field in a fully counter-balanced, within-subjects design. Subjects were run singly for one condition each day over 3 consecutive days with a field strength of 1.1 mT and a daily expose duration of 5 min. Neither magnetic field had any effect on RT at any time during the exposure. One condition of a second study, using a new group of 24 volunteer subjects, also failed to find any field effects at 0.2 Hz. Additionally, the second study failed to show any effects when the frequency, flux density, and field orientation were set according to parameter resonance theory. It is suggested that, although ELF magnetic field effects on human behavior may be elusive, future research can improve detection rates by paying greater attention to reducing error variance and increasing statistical power.

  3. A Longitudinal Study of Visual Expectation and Reaction Time in the First Year of Life.

    ERIC Educational Resources Information Center

    Rose, Susan A.; Feldman, Judith F.; Jankowski, Jeffery J.; Caro, Donna M.

    2002-01-01

    Examined developmental change and stability of visual expectation and reaction times among 5-, 7-, and 12-month-old term and preterm infants. Found that reaction times declined with age while anticipations increased. Infants with faster reaction times were more likely to anticipate upcoming events; this effect disappeared when time between stimuli…

  4. The acute effects of a warm-up including static or dynamic stretching on countermovement jump height, reaction time, and flexibility.

    PubMed

    Perrier, Erica T; Pavol, Michael J; Hoffman, Mark A

    2011-07-01

    The purpose of this research was to compare the effects of a warm-up with static vs. dynamic stretching on countermovement jump (CMJ) height, reaction time, and low-back and hamstring flexibility and to determine whether any observed performance deficits would persist throughout a series of CMJs. Twenty-one recreationally active men (24.4 ± 4.5 years) completed 3 data collection sessions. Each session included a 5-minute treadmill jog followed by 1 of the stretch treatments: no stretching (NS), static stretching (SS), or dynamic stretching (DS). After the jog and stretch treatment, the participant performed a sit-and-reach test. Next, the participant completed a series of 10 maximal-effort CMJs, during which he was asked to jump as quickly as possible after seeing a visual stimulus (light). The CMJ height and reaction time were determined from measured ground reaction forces. A treatment × jump repeated-measures analysis of variance for CMJ height revealed a significant main effect of treatment (p = 0.004). The CMJ height was greater for DS (43.0 cm) than for NS (41.4 cm) and SS (41.9 cm) and was not less for SS than for NS. Analysis also revealed a significant main effect of jump (p = 0.005) on CMJ height: Jump height decreased from the early to the late jumps. The analysis of reaction time showed no significant effect of treatment. Treatment had a main effect (p < 0.001) on flexibility, however. Flexibility was greater after both SS and DS compared to after NS, with no difference in flexibility between SS and DS. Athletes in sports requiring lower-extremity power should use DS techniques in warm-up to enhance flexibility while improving performance.

  5. Simple reaction time to the onset of time-varying sounds.

    PubMed

    Schlittenlacher, Josef; Ellermeier, Wolfgang

    2015-10-01

    Although auditory simple reaction time (RT) is usually defined as the time elapsing between the onset of a stimulus and a recorded reaction, a sound cannot be specified by a single point in time. Therefore, the present work investigates how the period of time immediately after onset affects RT. By varying the stimulus duration between 10 and 500 msec, this critical duration was determined to fall between 32 and 40 milliseconds for a 1-kHz pure tone at 70 dB SPL. In a second experiment, the role of the buildup was further investigated by varying the rise time and its shape. The increment in RT for extending the rise time by a factor of ten was about 7 to 8 msec. There was no statistically significant difference in RT between a Gaussian and linear rise shape. A third experiment varied the modulation frequency and point of onset of amplitude-modulated tones, producing onsets at different initial levels with differently rapid increase or decrease immediately afterwards. The results of all three experiments results were explained very well by a straightforward extension of the parallel grains model (Miller and Ulrich Cogn. Psychol. 46, 101-151, 2003), a probabilistic race model employing many parallel channels. The extension of the model to time-varying sounds made the activation of such a grain depend on intensity as a function of time rather than a constant level. A second approach by mechanisms known from loudness produced less accurate predictions.

  6. Manual choice reaction times in the rate-domain

    PubMed Central

    Harris, Christopher M.; Waddington, Jonathan; Biscione, Valerio; Manzi, Sean

    2014-01-01

    Over the last 150 years, human manual reaction times (RTs) have been recorded countless times. Yet, our understanding of them remains remarkably poor. RTs are highly variable with positively skewed frequency distributions, often modeled as an inverse Gaussian distribution reflecting a stochastic rise to threshold (diffusion process). However, latency distributions of saccades are very close to the reciprocal Normal, suggesting that “rate” (reciprocal RT) may be the more fundamental variable. We explored whether this phenomenon extends to choice manual RTs. We recorded two-alternative choice RTs from 24 subjects, each with 4 blocks of 200 trials with two task difficulties (easy vs. difficult discrimination) and two instruction sets (urgent vs. accurate). We found that rate distributions were, indeed, very close to Normal, shifting to lower rates with increasing difficulty and accuracy, and for some blocks they appeared to become left-truncated, but still close to Normal. Using autoregressive techniques, we found temporal sequential dependencies for lags of at least 3. We identified a transient and steady-state component in each block. Because rates were Normal, we were able to estimate autoregressive weights using the Box-Jenkins technique, and convert to a moving average model using z-transforms to show explicit dependence on stimulus input. We also found a spatial sequential dependence for the previous 3 lags depending on whether the laterality of previous trials was repeated or alternated. This was partially dissociated from temporal dependency as it only occurred in the easy tasks. We conclude that 2-alternative choice manual RT distributions are close to reciprocal Normal and not the inverse Gaussian. This is not consistent with stochastic rise to threshold models, and we propose a simple optimality model in which reward is maximized to yield to an optimal rate, and hence an optimal time to respond. We discuss how it might be implemented. PMID:24959134

  7. Anion size of sodium salts and simple taste reaction times.

    PubMed

    Delwiche, J F; Halpern, B P; Desimone, J A

    1999-03-01

    Simple taste reaction times (RT) and taste intensities were measured in adult humans for 100-mM aqueous solutions of sodium chloride, acetate, glutamate, ascorbate, and gluconate flowed over the anterodorsal tongue with a closed liquid delivery system. Results from 12 subjects showed a significant increase in RT with molecular weight of the tastant, and a correlation of 0.941 between RT and the square roots of anionic weights. A multiple regression analysis controlling for perceived taste intensity indicated that RT increased linearly with the square root of the anionic weight. These findings support a model that includes both the permeability of ions through the tight junctions between the taste receptor cells of fungiform papillae taste buds and the effects of ions at apical portions of the receptor cells. They also suggest that gustatory transduction of sodium salts in humans normally involves intercellular spaces of taste buds as part of the functional sensory structures, in addition to individual taste receptor cells. PMID:10222469

  8. Exploration of Reaction Time: Ideas for an Inquiry Investigation in Physics Education

    ERIC Educational Resources Information Center

    Brown, Todd; Brown, Katrina; Barnot, Vickilyn

    2012-01-01

    Reaction time, the time between a stimulus and a person's reaction to it, is a concept familiar to most teenagers, particularly in the context of driving. We describe a simple inexpensive activity that utilizes students' creativity and invokes the scientific method in order to explore reaction time. The goal of the activity is to give students a…

  9. The effect of chromatic and luminance information on reaction times.

    PubMed

    O'Donell, Beatriz M; Barraza, Jose F; Colombo, Elisa M

    2010-07-01

    We present a series of experiments exploring the effect of chromaticity on reaction time (RT) for a variety of stimulus conditions, including chromatic and luminance contrast, luminance, and size. The chromaticity of these stimuli was varied along a series of vectors in color space that included the two chromatic-opponent-cone axes, a red-green (L-M) axis and a blue-yellow [S - (L + M)] axis, and intermediate noncardinal orientations, as well as the luminance axis (L + M). For Weber luminance contrasts above 10-20%, RTs tend to the same asymptote, irrespective of chromatic direction. At lower luminance contrast, the addition of chromatic information shortens the RT. RTs are strongly influenced by stimulus size when the chromatic stimulus is modulated along the [S - (L + M)] pathway and by stimulus size and adaptation luminance for the (L-M) pathway. RTs are independent of stimulus size for stimuli larger than 0.5 deg. Data are modeled with a modified version of Pieron's formula with an exponent close to 2, in which the stimulus intensity term is replaced by a factor that considers the relative effects of chromatic and achromatic information, as indexed by the RMS (square-root of the cone contrast) value at isoluminance and the Weber luminance contrast, respectively. The parameters of the model reveal how RT is linked to stimulus size, chromatic channels, and adaptation luminance and how they can be interpreted in terms of two chromatic mechanisms. This equation predicts that, for isoluminance, RTs for a stimulus lying on the S-cone pathway are higher than those for a stimulus lying on the L-M-cone pathway, for a given RMS cone contrast. The equation also predicts an asymptotic trend to the RT for an achromatic stimulus when the luminance contrast is sufficiently large.

  10. Exploring Listeners' Real-Time Reactions to Regional Accents

    ERIC Educational Resources Information Center

    Watson, Kevin; Clark, Lynn

    2015-01-01

    Evaluative reactions to language stimuli are presumably dynamic events, constantly changing through time as the signal unfolds, yet the tools we usually use to capture these reactions provide us with only a snapshot of this process by recording reactions at a single point in time. This paper outlines and evaluates a new methodology which employs…

  11. Reaction Time in a Visual 4-Choice Reaction Time Task: ERP Effects of Motor Preparation and Hemispheric Involvement.

    PubMed

    Antonova, Ingrida; van Swam, Claudia; Hubl, Daniela; Dierks, Thomas; Griskova-Bulanova, Inga; Koenig, Thomas

    2016-07-01

    Reaction time (RT), the most common measure of CNS efficiency, shows intra- and inter-individual variability. This may be accounted for by hemispheric specialization, individual neuroanatomy, and transient functional fluctuations between trials. To explore RT on these three levels, ERPs were measured in a visual 4-choice RT task with lateralized stimuli (left lateral, left middle, right middle, and right lateral) in 28 healthy right-handed subjects. We analyzed behavioral data, ERP microstates (MS), N1 and P3 components, and trial-by-trial variance. Across subjects, the N1 component was contralateral to the stimulation side. N1-MSs were stronger over the left hemisphere, and middle stimulation evoked stronger activation than lateral stimulation in both hemispheres. The P3 was larger for the right visual field stimulation. RTs were shorter for the right visual hemifield stimulation/right hand responses. Within subjects, covariance analysis of single trial ERPs with RTs showed consistent lateralized predictors of RT over the motor cortex (MC) in the 112-248 ms interval. Decreased RTs were related to negativity over the MC contralateral to the stimulation side, an effect that could be interpreted as the lateralized readiness potential (LRP), and which was strongest for right side stimulation. The covariance analysis linking individual mean RTs and individual mean ERPs showed a frontal negativity and an occipital positivity correlating with decreased RTs in the 212-232 ms interval. We concluded that a particular RT is a composite measure that depends on the appropriateness of the motor preparation to a particular response and on stimulus lateralization that selectively involves a particular hemisphere.

  12. Analysis of the Escherichia coli genome. V. DNA sequence of the region from 76.0 to 81.5 minutes.

    PubMed Central

    Sofia, H J; Burland, V; Daniels, D L; Plunkett, G; Blattner, F R

    1994-01-01

    The DNA sequence of a 225.4 kilobase segment of the Escherichia coli K-12 genome is described here, from 76.0 to 81.5 minutes on the genetic map. This brings the total of contiguous sequence from the E.coli genome project to 725.1 kb (76.0 to 92.8 minutes). We found 191 putative coding genes (ORFs) of which 72 genes were previously known, and 110 of which remain unidentified despite literature and similarity searches. Seven new genes--arsE, arsF, arsG, treF, xylR, xylG, and xylH--were identified as well as the previously mapped pit and dctA genes. The arrangement of proposed genes relative to possible promoters and terminators suggests 90 potential transcription units. Other features include 19 REP elements, 95 computer-predicted bends, 50 Chi sites, and one grey hole. Thirty-one putative signal peptides were found, including those of thirteen known membrane or periplasmic proteins. One tRNA gene (proK) and two insertion sequences (IS5 and IS150) are located in this segment. The genes in this region are organized with equal numbers oriented with or against replication. PMID:8041620

  13. Estimation of 24-hour thyroid uptake of I-131 sodium iodide using a 5-minute uptake of technetium-99m pertechnetate

    SciTech Connect

    Smith, J.J.; Croft, B.Y.; Brookeman, V.A.; Teates, C.D. )

    1990-02-01

    The authors have developed a method to estimate the 24-hour sodium iodide thyroid uptake based on a 5-minute Tc-99m pertechnetate thyroid uptake using the equation: Estimated Iodide Uptake = 17.72*In(Pertechnetate Uptake) + 30.40. This estimation has a correlation coefficient of 0.90. It is based on a data pool of 44 patients who underwent I-131 and Tc-99m studies within 2 weeks of each other from 1978-1988, with established diagnoses as follows: 12 euthyroid, 6 hyperthyroid with multinodular goiters, 15 hyperthyroid with diffuse goiters, 4 with subacute thyroiditis, and 7 unknown. The population consisted of 30 women and 14 men with a mean age of 52.0 +/- 17.5 years; this sample was screened for use of thyroid hormone, propylthiouracil, and radiographic contrast. The authors believe this estimation method is of value whenever a 24-hour iodide uptake is desired, and where speed and minimizing radiation dose are factors. This method is strongly recommended for thyroid uptake evaluation before I-131 therapy.

  14. Problem-Solving Test: Real-Time Polymerase Chain Reaction

    ERIC Educational Resources Information Center

    Szeberenyi, Jozsef

    2009-01-01

    Terms to be familiar with before you start to solve the test: polymerase chain reaction, DNA amplification, electrophoresis, breast cancer, "HER2" gene, genomic DNA, "in vitro" DNA synthesis, template, primer, Taq polymerase, 5[prime][right arrow]3[prime] elongation activity, 5[prime][right arrow]3[prime] exonuclease activity, deoxyribonucleoside…

  15. Time-dependent Green's functions approach to nuclear reactions

    SciTech Connect

    Rios, Arnau; Danielewicz, Pawel

    2008-04-04

    Nonequilibrium Green's functions represent underutilized means of studying evolution of quantum many-body systems. In view of a rising computer power, an effort is underway to apply the Green's functions to the dynamics of central nuclear reactions. As the first step, mean-field evolution for the density matrix for colliding slabs is studied in one dimension. Strategy to extend the dynamics to correlations is described.

  16. Kinetics of coal liquefaction at very short reaction times

    SciTech Connect

    Huang, H.; Wang, K.; Wang, S.

    1995-12-31

    Kinetics of direct liquefaction of Illinois No. 6 Bituminous coal in tetralin has been investigated at three temperatures (309-424{degrees}C) during the first few seconds of the reaction and up to an hour. Conversion was followed by the ash content of the coal residue as determined by TGA, and changes in the reaction were followed by changes in the TGA parameters, such as Volatile Matter (VM) and Fixed Carbon (FC). The effects of temperature on the reaction kinetics were in both catalyzed and uncatalyzed liquefaction with a large excess of tetralin, there is an initial very rapid extraction of the soluble matter by the tetralin. After extraction there is an induction period followed by a slower rate of conversion of the coal structure itself. At higher temperatures, the amount of extraction increases and the induction period becomes shorter. At least two conflicting processes are occurring in the last stage: (1) breakdown of the coal structure to liquid products, and (2) formation of retrograde material (precursor of tar and coke). Catalysts such as sulfided molybdenum naphthenate in the presence of hydrogen greatly reduce the formation of retrograde products.

  17. The immediate effects of keyboard-based music therapy on probe reaction time.

    PubMed

    Zhang, Xiaoying; Zhou, Yue; Liu, Songhuai

    2016-07-01

    [Purpose] This study examined the immediate effects of keyboard-based music therapy on Probe Reaction Time. [Subjects and Methods] Probe Reaction Time was determined in 10 subjects by self-evaluation before and after music therapy intervention. The Probe Reaction Time was separately measured 4 times. [Results] After completion of music therapy intervention, the Probe Reaction Time in the 10 subjects was significantly decreased. [Conclusion] The results suggest that keyboard-based music therapy is an effective and novel treatment, and should be applied in clinical practice.

  18. The immediate effects of keyboard-based music therapy on probe reaction time.

    PubMed

    Zhang, Xiaoying; Zhou, Yue; Liu, Songhuai

    2016-07-01

    [Purpose] This study examined the immediate effects of keyboard-based music therapy on Probe Reaction Time. [Subjects and Methods] Probe Reaction Time was determined in 10 subjects by self-evaluation before and after music therapy intervention. The Probe Reaction Time was separately measured 4 times. [Results] After completion of music therapy intervention, the Probe Reaction Time in the 10 subjects was significantly decreased. [Conclusion] The results suggest that keyboard-based music therapy is an effective and novel treatment, and should be applied in clinical practice. PMID:27512274

  19. The immediate effects of keyboard-based music therapy on probe reaction time

    PubMed Central

    Zhang, Xiaoying; Zhou, Yue; Liu, Songhuai

    2016-01-01

    [Purpose] This study examined the immediate effects of keyboard-based music therapy on Probe Reaction Time. [Subjects and Methods] Probe Reaction Time was determined in 10 subjects by self-evaluation before and after music therapy intervention. The Probe Reaction Time was separately measured 4 times. [Results] After completion of music therapy intervention, the Probe Reaction Time in the 10 subjects was significantly decreased. [Conclusion] The results suggest that keyboard-based music therapy is an effective and novel treatment, and should be applied in clinical practice. PMID:27512274

  20. Effects of reaction time variability and age on brain activity during Stroop task performance.

    PubMed

    Tam, Angela; Luedke, Angela C; Walsh, Jeremy J; Fernandez-Ruiz, Juan; Garcia, Angeles

    2015-09-01

    Variability in reaction time during task performance may reflect fluctuations in attention and cause reduced performance in goal-directed tasks, yet it is unclear whether the mechanisms behind this phenomenon change with age. Using fMRI, we tested young and cognitively healthy older adults with the Stroop task to determine whether aging affects the neural mechanisms underlying intra-individual reaction time variability. We found significant between-group differences in BOLD activity modulated by reaction time. In older adults, longer reaction times were associated with greater activity in frontoparietal attentional areas, while in younger adults longer reaction times were associated with greater activity in default mode network areas. Our results suggest that the neural correlates of reaction time variability change with healthy aging, reinforcing the concept of functional plasticity to maintain high cognitive function throughout the lifespan.

  1. Effects of cocaine on simple reaction times and sensory thresholds in baboons.

    PubMed Central

    Hienz, R D; Spear, D J; Bowers, D A

    1994-01-01

    The effects of chronic, daily administration of cocaine on auditory and visual reaction times and thresholds were studied in baboons. Single intramuscular injections of cocaine hydrochloride (0.1 to 5.6 mg/kg) were given once daily for periods of 10 to 25 days, and were followed immediately by psychophysical tests designed to assess cocaine's effects on simple reaction times as on auditory and visual threshold functions. Consistent reductions in reaction times were frequently observed over the cocaine dose range of 0.32 to 1.0 mg/kg; at higher doses, either decreases or increases in reaction times were observed, depending upon the animal. Lowered reaction times generally occurred immediately following the 1st day's cocaine injection, and continued through all subsequent days during the dose administration period, suggesting little development of tolerance or sensitivity to these reaction-time effects. Reaction-time decreases showed a U-shaped dose-effect function. The greatest decreases in reaction times occurred from 0.32 to 1.0 mg/kg, and produced an average reaction-time decrease of 10 to 12%. Concurrently measured auditory and visual thresholds showed no systematic changes as a function of cocaine dose. Pausing was observed during performance of the psychophysical tasks, with the length of total session pause times being directly related to cocaine dose. PMID:8169572

  2. [Correlation between Sensory Gating P50, Mismatch Negativity, and Reaction Time].

    PubMed

    Aleksandrov, A A; Dmitrieva, E S; Stankevich, L N

    2015-01-01

    This paper is about the correlation pre-attentive processes, such as P50 sensory gating (SG P50) and mismatch negativity (MMN) with each other and with sensorimotor reaction time (RT). SG P50 data were obtained in the standard paired-click paradigm, MMN was measured in the passive odd-ball paradigm sensorimotor reaction time was studied in an active odd-ball paradigm. Was obtained positive correlation sensory gating P50 with amplitude mismatch negativity, amplitude mismatch negativity with sensorimotor reaction time, sensory gating P50 with sensorimotor reaction time.

  3. A Comparative Study on Visual Choice Reaction Time for Different Colors in Females

    PubMed Central

    Balakrishnan, Grrishma; Uppinakudru, Gurunandan; Girwar Singh, Gaur; Bangera, Shobith; Dutt Raghavendra, Aswini; Thangavel, Dinesh

    2014-01-01

    Reaction time is one of the important methods to study a person's central information processing speed and coordinated peripheral movement response. Visual choice reaction time is a type of reaction time and is very important for drivers, pilots, security guards, and so forth. Previous studies were mainly on simple reaction time and there are very few studies on visual choice reaction time. The aim of our study was to compare the visual choice reaction time for red, green, and yellow colors of 60 healthy undergraduate female volunteers. After giving adequate practice, visual choice reaction time was recorded for red, green, and yellow colors using reaction time machine (RTM 608, Medicaid, Chandigarh). Repeated measures of ANOVA and Bonferroni multiple comparison were used for analysis and P < 0.05 was considered statistically significant. The results showed that both red and green had significantly less choice visual choice reaction (P values <0.0001 and 0.0002) when compared with yellow. This could be because individual color mental processing time for yellow color is more than red and green. PMID:25580294

  4. Reaction time in gait initiation depends on the time available for affective processing.

    PubMed

    Gélat, Thierry; Chapus, Carole Ferrel

    2015-11-16

    Previous studies have reported that reaction time in gait initiation was affected by emotion eliciting pictures. This study examined the effect of a change in the delay between image onset and the imperative "go" on reaction time. From a standing posture, 19 young adults had to walk (several steps) toward pleasant or unpleasant images in two conditions. In the short condition, the word "go" appeared 500ms after image onset and participants were instructed to initiate gait as soon as possible after the word go appeared. In the long condition, the same procedure was used but the word "go" appeared 3000ms after image onset. Results demonstrated that motor responses were faster for pleasant pictures than unpleasant ones in the short condition. In contrast, no significant difference was found between both categories of pictures in the long condition. Moreover, we found that self ratings of valence of unpleasant pictures were less unpleasant in the long condition than in the short one whereas there was no difference for pleasant pictures between both conditions. This result reflected a change in the affective significance of unpleasant pictures in the long condition. We also found in the long condition, that the body was inclined forward and to the stance limb during the standing posture and importantly with a similar extent for pleasant and unpleasant pictures. This change clearly reflected a facilitation of the gait initiation process. Overall, results suggested that this gait facilitation when confronted to unpleasant pictures resulted from emotional regulation processes enabling to reappraise these pictures and to override the initial avoidance tendency that they caused. PMID:26455865

  5. A time-indexed reference standard of adverse drug reactions.

    PubMed

    Harpaz, Rave; Odgers, David; Gaskin, Greg; DuMouchel, William; Winnenburg, Rainer; Bodenreider, Olivier; Ripple, Anna; Szarfman, Ana; Sorbello, Alfred; Horvitz, Eric; White, Ryen W; Shah, Nigam H

    2014-11-11

    Undetected adverse drug reactions (ADRs) pose a major burden on the health system. Data mining methodologies designed to identify signals of novel ADRs are of deep importance for drug safety surveillance. The development and evaluation of these methodologies requires proper reference benchmarks. While progress has recently been made in developing such benchmarks, our understanding of the performance characteristics of the data mining methodologies is limited because existing benchmarks do not support prospective performance evaluations. We address this shortcoming by providing a reference standard to support prospective performance evaluations. The reference standard was systematically curated from drug labeling revisions, such as new warnings, which were issued and communicated by the US Food and Drug Administration in 2013. The reference standard includes 62 positive test cases and 75 negative controls, and covers 44 drugs and 38 events. We provide usage guidance and empirical support for the reference standard by applying it to analyze two data sources commonly mined for drug safety surveillance.

  6. A time-indexed reference standard of adverse drug reactions

    PubMed Central

    Harpaz, Rave; Odgers, David; Gaskin, Greg; DuMouchel, William; Winnenburg, Rainer; Bodenreider, Olivier; Ripple, Anna; Szarfman, Ana; Sorbello, Alfred; Horvitz, Eric; White, Ryen W.; Shah, Nigam H.

    2014-01-01

    Undetected adverse drug reactions (ADRs) pose a major burden on the health system. Data mining methodologies designed to identify signals of novel ADRs are of deep importance for drug safety surveillance. The development and evaluation of these methodologies requires proper reference benchmarks. While progress has recently been made in developing such benchmarks, our understanding of the performance characteristics of the data mining methodologies is limited because existing benchmarks do not support prospective performance evaluations. We address this shortcoming by providing a reference standard to support prospective performance evaluations. The reference standard was systematically curated from drug labeling revisions, such as new warnings, which were issued and communicated by the US Food and Drug Administration in 2013. The reference standard includes 62 positive test cases and 75 negative controls, and covers 44 drugs and 38 events. We provide usage guidance and empirical support for the reference standard by applying it to analyze two data sources commonly mined for drug safety surveillance. PMID:25632348

  7. Inter-session reliability and sex-related differences in hamstrings total reaction time, pre-motor time and motor time during eccentric isokinetic contractions in recreational athlete.

    PubMed

    Ayala, Francisco; De Ste Croix, Mark; Sainz de Baranda, Pilar; Santonja, Fernando

    2014-04-01

    The purposes were twofold: (a) to ascertain the inter-session reliability of hamstrings total reaction time, pre-motor time and motor time; and (b) to examine sex-related differences in the hamstrings reaction times profile. Twenty-four men and 24 women completed the study. Biceps femoris and semitendinosus total reaction time, pre-motor time and motor time measured during eccentric isokinetic contractions were recorded on three different occasions. Inter-session reliability was examined through typical percentage error (CVTE), percentage change in the mean (CM) and intraclass correlations (ICC). For both biceps femoris and semitendinosus, total reaction time, pre-motor time and motor time measures demonstrated moderate inter-session reliability (CVTE<10%; CM<3%; ICC>0.7). The results also indicated that, although not statistically significant, women reported consistently longer hamstrings total reaction time (23.5ms), pre-motor time (12.7ms) and motor time (7.5ms) values than men. Therefore, an observed change larger than 5%, 9% and 8% for total reaction time, pre-motor time and motor time respectively from baseline scores after performing a training program would indicate that a real change was likely. Furthermore, while not statistically significant, sex differences were noted in the hamstrings reaction time profile which may play a role in the greater incidence of ACL injuries in women.

  8. In Reaction to Columbine, "Times" Focuses on Culture of Violence.

    ERIC Educational Resources Information Center

    Donofrio, Leana; Richards, Megan

    1999-01-01

    Describes how "The Lakewood Times" (Lakewood, Ohio) covered the shootings at Columbine High School. Suggests that the newspaper covered the story differently than other media by taking many different angles to the story. (RS)

  9. Time out

    MedlinePlus

    ... but no more than 5 minutes. Once your child shows bad behavior, explain clearly what the unacceptable behavior is, and ... time out. Be ready with praise if your child stops the behavior. If the behavior does not stop, tell your ...

  10. Geologic map and database of the Salem East and Turner 7.5-minute quadrangles, Marion County, Oregon: a digital database

    USGS Publications Warehouse

    Tolan, Terry L.; Beeson, Marvin H.; Digital Database by DuRoss, Christopher B.

    2000-01-01

    The Salem East and Turner 7.5-minute quadrangles are situated in the center of the Willamette Valley near the western margin of the Columbia River Basalt Group (CRBG) distribution. The terrain within the area is of low to moderate relief, ranging from about 150 to almost 1,100-ft elevation. Mill Creek flows northward from the Stayton basin (Turner quadrangle) to the northern Willamette Valley (Salem East quadrangle) through a low that dissects the Columbia River basalt that forms the Salem Hills on the west and the Waldo Hills to the east. Approximately eight flows of CRBG form a thickness of up to 700� in these two quadrangles. The Ginkgo intracanyon flow that extends from east to west through the south half of the Turner quadrangle is exposed in the hills along the southeast part of the quadrangle. Previous geologic mapping by Thayer (1939) and Bela (1981) while providing the general geologic framework did not subdivide the CRBG which limited their ability to delineate structural elements. Reconnaissance mapping of the CRBG units in the Willamette Valley indicated that these stratigraphic units could serve as a series of unique reference horizons for identifying post-Miocene folding and faulting (Beeson and others, 1985,1989; Beeson and Tolan, 1990). Crenna, et al. (1994) compiled previous mapping in the Willamette Valley in a study of the tectonics of the Salem area. The major emphasis of this study was to identify and map CRBG units within the Salem East and Turner Quadrangles and to utilize this detailed CRBG stratigraphy to identify and characterize structural features. Water well logs were used to provide better subsurface stratigraphic control. Three other quadrangles (Scotts Mills, Silverton, and Stayton NE) in the Willamette Valley have been mapped in this way (Tolan and Beeson, 1999). This area was a lowland area of weathered and eroded marine sedimentary when the Columbia River basalts encroached on this area approximately 15-16 m.y. ago. An

  11. Geologic framework, hydrostratigraphy, and ichnology of the Blanco, Payton, and Rough Hollow 7.5-minute quadrangles, Blanco, Comal, Hays, and Kendall Counties, Texas

    USGS Publications Warehouse

    Clark, Allan K.; Golab, James A.; Morris, Robert E.

    2016-01-01

    This report presents the geologic framework, hydro­stratigraphy, and ichnology of the Trinity and Edwards Groups in the Blanco, Payton, and Rough Hollow 7.5-minute quad­rangles in Blanco, Comal, Hays, and Kendall Counties, Texas. Rocks exposed in the study area are of the Lower Cretaceous Trinity Group and lower part of the Fort Terrett Formation of the Lower Cretaceous Edwards Group. The mapped units in the study area are the Hammett Shale, Cow Creek Limestone, Hensell Sand, and Glen Rose Limestone of the Trinity Group and the lower portion of the Fort Terrett Formation of the Edwards Group. The Glen Rose Limestone is composed of the Lower and Upper Members. These Trinity Group rocks con­tain the upper and middle Trinity aquifers. The only remaining outcrops of the Edwards Group are the basal nodular member of the Fort Terrett Formation, which caps several hills in the northern portion of the study area. These rocks were deposited in an open marine to supratidal flats environment. The faulting and fracturing in the study area are part of the Balcones fault zone, an extensional system of faults that generally trends southwest to northeast in south-central Texas.The hydrostratigraphic units of the Edwards and Trinity aquifers were mapped and described using a classification system based on fabric-selective or not-fabric-selective poros­ity types. The only hydrostratigraphic unit of the Edwards aquifer present in the study area is hydrostratigraphic unit VIII. The mapped hydrostratigraphic units of the upper Trinity aquifer are (from top to bottom) the Camp Bullis, upper evaporite, fossiliferous, and lower evaporite which are interval equivalent to the Upper Member of the Glen Rose Limestone. The middle Trinity aquifer encompasses (from top to bottom) the Lower Member of the Glen Rose Limestone, the Hensell Sand Member, and the Cow Creek Limestone Member of the Pearsall Formation. The Lower Member of the Glen Rose Limestone is subdivided into six informal hydro

  12. Geologic framework, hydrostratigraphy, and ichnology of the Blanco, Payton, and Rough Hollow 7.5-minute quadrangles, Blanco, Comal, Hays, and Kendall Counties, Texas

    USGS Publications Warehouse

    Clark, Allan K.; Golab, James A.; Morris, Robert E.

    2016-09-13

    This report presents the geologic framework, hydro­stratigraphy, and ichnology of the Trinity and Edwards Groups in the Blanco, Payton, and Rough Hollow 7.5-minute quad­rangles in Blanco, Comal, Hays, and Kendall Counties, Texas. Rocks exposed in the study area are of the Lower Cretaceous Trinity Group and lower part of the Fort Terrett Formation of the Lower Cretaceous Edwards Group. The mapped units in the study area are the Hammett Shale, Cow Creek Limestone, Hensell Sand, and Glen Rose Limestone of the Trinity Group and the lower portion of the Fort Terrett Formation of the Edwards Group. The Glen Rose Limestone is composed of the Lower and Upper Members. These Trinity Group rocks con­tain the upper and middle Trinity aquifers. The only remaining outcrops of the Edwards Group are the basal nodular member of the Fort Terrett Formation, which caps several hills in the northern portion of the study area. These rocks were deposited in an open marine to supratidal flats environment. The faulting and fracturing in the study area are part of the Balcones fault zone, an extensional system of faults that generally trends southwest to northeast in south-central Texas.The hydrostratigraphic units of the Edwards and Trinity aquifers were mapped and described using a classification system based on fabric-selective or not-fabric-selective poros­ity types. The only hydrostratigraphic unit of the Edwards aquifer present in the study area is hydrostratigraphic unit VIII. The mapped hydrostratigraphic units of the upper Trinity aquifer are (from top to bottom) the Camp Bullis, upper evaporite, fossiliferous, and lower evaporite which are interval equivalent to the Upper Member of the Glen Rose Limestone. The middle Trinity aquifer encompasses (from top to bottom) the Lower Member of the Glen Rose Limestone, the Hensell Sand Member, and the Cow Creek Limestone Member of the Pearsall Formation. The Lower Member of the Glen Rose Limestone is subdivided into six informal hydro

  13. Chaotic flow and the finite-time Lyapunov exponent: Competitive autocatalytic reactions in advection-reaction-diffusion systems

    NASA Astrophysics Data System (ADS)

    Lueptow, Richard M.; Schlick, Conor P.; Umbanhowar, Paul B.; Ottino, Julio M.

    2013-11-01

    We investigate chaotic advection and diffusion in competitive autocatalytic reactions. To study this subject, we use a computationally efficient method for solving advection-reaction-diffusion equations for periodic flows using a mapping method with operator splitting. In competitive autocatalytic reactions, there are two species, B and C, which both react autocatalytically with species A (A +B -->2B and A +C -->2C). If there is initially a small amount of spatially localized B and C and a large amount of A, all three species will be advected by the velocity field, diffuse, and react until A is completely consumed and only B and C remain. We find that the small scale interactions associated with the chaotic velocity field, specifically the local finite-time Lyapunov exponents (FTLEs), can accurately predict the final average concentrations of B and C after the reaction is complete. The species, B or C, that starts in the region with the larger FTLE has, with high probability, the larger average concentration at the end of the reaction. If species B and C start in regions having similar FTLEs, their average concentrations at the end of the reaction will also be similar. Funded by NSF Grant CMMI-1000469.

  14. On the deduction of chemical reaction pathways from measurements of time series of concentrations

    NASA Astrophysics Data System (ADS)

    Samoilov, Michael; Arkin, Adam; Ross, John

    2001-03-01

    We discuss the deduction of reaction pathways in complex chemical systems from measurements of time series of chemical concentrations of reacting species. First we review a technique called correlation metric construction (CMC) and show the construction of a reaction pathway from measurements on a part of glycolysis. Then we present two new improved methods for the analysis of time series of concentrations, entropy metric construction (EMC), and entropy reduction method (ERM), and illustrate (EMC) with calculations on a model reaction system.

  15. The effects of alpha-2 agonist, medetomidine and its antagonist, atipamezole on reaction and movement times in a visual choice reaction time task in monkeys.

    PubMed

    Rämä, P; Linnankoski, I; Carlson, S

    1997-01-01

    Alpha-2 adrenoceptor agonists have been shown to improve the working memory task performance of aged monkeys. Suggestions offered to explain this finding include improved short-term memory processing, slight sedation, and decreased distractiveness. Although sedation is evident at high doses, it may also contribute to the working memory task performance at low doses. The aim of the present work was to find out whether the positive effects of an alpha-2 agonist, medetomidine, on working memory performance could be explained by its sedative effects. This was accomplished by measuring the reaction and movement times of monkeys performing a visual choice reaction time task under the influence of medetomidine or its antagonist atipamezole. In the task a trial began with the monkey holding a central pad. After a short period one of two lateral light emitting diodes was turned on for 300 ms and the monkeys were trained to release the central bar and touch either of the bars, situated below the diodes, depending on the location of the stimulus. The reaction and movement times were significantly longer than on saline control only at the highest dose of medetomidine (10.0 micrograms/kg). At the lowest dose of atipamezole (0.01 mg/kg), the reaction times were significantly shorter than on saline control. The results of this study demonstrate that low doses of medetomidine, which have earlier been shown to improve working memory performance, do not induce sedation as measured by reaction and movement times.

  16. Competitive autocatalytic reactions in chaotic flows with diffusion: Prediction using finite-time Lyapunov exponents

    NASA Astrophysics Data System (ADS)

    Schlick, Conor P.; Umbanhowar, Paul B.; Ottino, Julio M.; Lueptow, Richard M.

    2014-03-01

    We investigate chaotic advection and diffusion in autocatalytic reactions for time-periodic sine flow computationally using a mapping method with operator splitting. We specifically consider three different autocatalytic reaction schemes: a single autocatalytic reaction, competitive autocatalytic reactions, which can provide insight into problems of chiral symmetry breaking and homochirality, and competitive autocatalytic reactions with recycling. In competitive autocatalytic reactions, species B and C both undergo an autocatalytic reaction with species A such that A +B→2B and A +C→2C. Small amounts of initially spatially localized B and C and a large amount of spatially homogeneous A are advected by the velocity field, diffuse, and react until A is completely consumed and only B and C remain. We find that local finite-time Lyapunov exponents (FTLEs) can accurately predict the final average concentrations of B and C after the reaction completes. The species that starts in the region with the larger FTLE has, with high probability, the larger average concentration at the end of the reaction. If B and C start in regions with similar FTLEs, their average concentrations at the end of the reaction will also be similar. When a recycling reaction is added, the system evolves towards a single species state, with the FTLE often being useful in predicting which species fills the entire domain and which is depleted. The FTLE approach is also demonstrated for competitive autocatalytic reactions in journal bearing flow, an experimentally realizable flow that generates chaotic dynamics.

  17. Competitive autocatalytic reactions in chaotic flows with diffusion: prediction using finite-time Lyapunov exponents.

    PubMed

    Schlick, Conor P; Umbanhowar, Paul B; Ottino, Julio M; Lueptow, Richard M

    2014-03-01

    We investigate chaotic advection and diffusion in autocatalytic reactions for time-periodic sine flow computationally using a mapping method with operator splitting. We specifically consider three different autocatalytic reaction schemes: a single autocatalytic reaction, competitive autocatalytic reactions, which can provide insight into problems of chiral symmetry breaking and homochirality, and competitive autocatalytic reactions with recycling. In competitive autocatalytic reactions, species B and C both undergo an autocatalytic reaction with species A such that [Formula: see text] and [Formula: see text]. Small amounts of initially spatially localized B and C and a large amount of spatially homogeneous A are advected by the velocity field, diffuse, and react until A is completely consumed and only B and C remain. We find that local finite-time Lyapunov exponents (FTLEs) can accurately predict the final average concentrations of B and C after the reaction completes. The species that starts in the region with the larger FTLE has, with high probability, the larger average concentration at the end of the reaction. If B and C start in regions with similar FTLEs, their average concentrations at the end of the reaction will also be similar. When a recycling reaction is added, the system evolves towards a single species state, with the FTLE often being useful in predicting which species fills the entire domain and which is depleted. The FTLE approach is also demonstrated for competitive autocatalytic reactions in journal bearing flow, an experimentally realizable flow that generates chaotic dynamics.

  18. Competitive autocatalytic reactions in chaotic flows with diffusion: Prediction using finite-time Lyapunov exponents

    SciTech Connect

    Schlick, Conor P.; Umbanhowar, Paul B.; Ottino, Julio M.; Lueptow, Richard M.

    2014-03-15

    We investigate chaotic advection and diffusion in autocatalytic reactions for time-periodic sine flow computationally using a mapping method with operator splitting. We specifically consider three different autocatalytic reaction schemes: a single autocatalytic reaction, competitive autocatalytic reactions, which can provide insight into problems of chiral symmetry breaking and homochirality, and competitive autocatalytic reactions with recycling. In competitive autocatalytic reactions, species B and C both undergo an autocatalytic reaction with species A such that A+B→2B and A+C→2C. Small amounts of initially spatially localized B and C and a large amount of spatially homogeneous A are advected by the velocity field, diffuse, and react until A is completely consumed and only B and C remain. We find that local finite-time Lyapunov exponents (FTLEs) can accurately predict the final average concentrations of B and C after the reaction completes. The species that starts in the region with the larger FTLE has, with high probability, the larger average concentration at the end of the reaction. If B and C start in regions with similar FTLEs, their average concentrations at the end of the reaction will also be similar. When a recycling reaction is added, the system evolves towards a single species state, with the FTLE often being useful in predicting which species fills the entire domain and which is depleted. The FTLE approach is also demonstrated for competitive autocatalytic reactions in journal bearing flow, an experimentally realizable flow that generates chaotic dynamics.

  19. Temporal Frequency Modulates Reaction Time Responses to First-Order and Second-Order Motion

    ERIC Educational Resources Information Center

    Hutchinson, Claire V.; Ledgeway, Tim

    2010-01-01

    This study investigated the effect of temporal frequency and modulation depth on reaction times for discriminating the direction of first-order (luminance-defined) and second-order (contrast-defined) motion, equated for visibility using equal multiples of direction-discrimination threshold. Results showed that reaction times were heavily…

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

    ERIC Educational Resources Information Center

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

    2011-01-01

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

  1. Individual Differences in Components of Reaction Time Distributions and Their Relations to Working Memory and Intelligence

    ERIC Educational Resources Information Center

    Schmiedek, Florian; Oberauer, Klaus; Wilhelm, Oliver; Suss, Heinz-Martin; Wittmann, Werner W.

    2007-01-01

    The authors bring together approaches from cognitive and individual differences psychology to model characteristics of reaction time distributions beyond measures of central tendency. Ex-Gaussian distributions and a diffusion model approach are used to describe individuals' reaction time data. The authors identified common latent factors for each…

  2. Effects of Long-Time Reading Experience on Reaction Time and the Recognition Potential

    PubMed Central

    Rudell, Alan P.; Hu, Bin

    2010-01-01

    The proposition that long-time experience in reading a language gradually builds up rapidly acting neural processes that facilitate the processing of words in that language and speed them into conscious awareness was examined. Behavioral reaction time (RT) and electrophysiological responsiveness to visually displayed words and non-language images were measured in persons who differed in how much experience they had in reading English. The electrophysiological response was the recognition potential (RP). Behavioral RT and the latency of the RP to English words were both expected to depend upon how much English reading experience a person had. The short latency of the RP was expected to free it from the influence of non-perceptual factors that affect RT, such as speed/accuracy tradeoff. This expectation yielded the prediction that the behavioral and electrophysiological results would differ in a specific way. Long-time readers of English were expected to show shorter RP latency to English words than less experienced (China-educated) readers of English but no RP latency difference for non-language images, with which neither group had greater experience. In contrast, due to speed accuracy tradeoff, the China-educated subjects were expected to show longer RT for both the words and the non-language images. The prediction was confirmed. The amount of language experience that a person had showed a stronger relationship to RP latency than it did to RT. This helped to validate the use of the RP as a tool for investigating perception and demonstrated definite advantages that it has for studying acquired perceptual processes in humans. PMID:20307598

  3. Voice reaction times with recognition for Commodore computers

    NASA Technical Reports Server (NTRS)

    Washburn, David A.; Putney, R. Thompson

    1990-01-01

    Hardware and software modifications are presented that allow for collection and recognition by a Commodore computer of spoken responses. Responses are timed with millisecond accuracy and automatically analyzed and scored. Accuracy data for this device from several experiments are presented. Potential applications and suggestions for improving recognition accuracy are also discussed.

  4. Space and time-resolved probing of heterogeneous catalysis reactions using lab-on-a-chip

    NASA Astrophysics Data System (ADS)

    Navin, Chelliah V.; Krishna, Katla Sai; Theegala, Chandra S.; Kumar, Challa S. S. R.

    2016-03-01

    Probing catalytic reactions on a catalyst surface in real time is a major challenge. Herein, we demonstrate the utility of a continuous flow millifluidic chip reactor coated with a nanostructured gold catalyst as an effective platform for in situ investigation of the kinetics of catalytic reactions by taking 5-(hydroxymethyl)furfural (HMF) to 2,5-furandicarboxylic acid (FDCA) conversion as a model reaction. The idea conceptualized in this paper can not only dramatically change the ability to probe the time-resolved kinetics of heterogeneous catalysis reactions but also used for investigating other chemical and biological catalytic processes, thereby making this a broad platform for probing reactions as they occur within continuous flow reactors.Probing catalytic reactions on a catalyst surface in real time is a major challenge. Herein, we demonstrate the utility of a continuous flow millifluidic chip reactor coated with a nanostructured gold catalyst as an effective platform for in situ investigation of the kinetics of catalytic reactions by taking 5-(hydroxymethyl)furfural (HMF) to 2,5-furandicarboxylic acid (FDCA) conversion as a model reaction. The idea conceptualized in this paper can not only dramatically change the ability to probe the time-resolved kinetics of heterogeneous catalysis reactions but also used for investigating other chemical and biological catalytic processes, thereby making this a broad platform for probing reactions as they occur within continuous flow reactors. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr06752a

  5. Stochastic modeling of biochemical systems with multistep reactions using state-dependent time delay.

    PubMed

    Wu, Qianqian; Tian, Tianhai

    2016-08-24

    To deal with the growing scale of molecular systems, sophisticated modelling techniques have been designed in recent years to reduce the complexity of mathematical models. Among them, a widely used approach is delayed reaction for simplifying multistep reactions. However, recent research results suggest that a delayed reaction with constant time delay is unable to describe multistep reactions accurately. To address this issue, we propose a novel approach using state-dependent time delay to approximate multistep reactions. We first use stochastic simulations to calculate time delay arising from multistep reactions exactly. Then we design algorithms to calculate time delay based on system dynamics precisely. To demonstrate the power of proposed method, two processes of mRNA degradation are used to investigate the function of time delay in determining system dynamics. In addition, a multistep pathway of metabolic synthesis is used to explore the potential of the proposed method to simplify multistep reactions with nonlinear reaction rates. Simulation results suggest that the state-dependent time delay is a promising and accurate approach to reduce model complexity and decrease the number of unknown parameters in the models.

  6. Stochastic modeling of biochemical systems with multistep reactions using state-dependent time delay.

    PubMed

    Wu, Qianqian; Tian, Tianhai

    2016-01-01

    To deal with the growing scale of molecular systems, sophisticated modelling techniques have been designed in recent years to reduce the complexity of mathematical models. Among them, a widely used approach is delayed reaction for simplifying multistep reactions. However, recent research results suggest that a delayed reaction with constant time delay is unable to describe multistep reactions accurately. To address this issue, we propose a novel approach using state-dependent time delay to approximate multistep reactions. We first use stochastic simulations to calculate time delay arising from multistep reactions exactly. Then we design algorithms to calculate time delay based on system dynamics precisely. To demonstrate the power of proposed method, two processes of mRNA degradation are used to investigate the function of time delay in determining system dynamics. In addition, a multistep pathway of metabolic synthesis is used to explore the potential of the proposed method to simplify multistep reactions with nonlinear reaction rates. Simulation results suggest that the state-dependent time delay is a promising and accurate approach to reduce model complexity and decrease the number of unknown parameters in the models. PMID:27553753

  7. Stochastic modeling of biochemical systems with multistep reactions using state-dependent time delay

    PubMed Central

    Wu, Qianqian; Tian, Tianhai

    2016-01-01

    To deal with the growing scale of molecular systems, sophisticated modelling techniques have been designed in recent years to reduce the complexity of mathematical models. Among them, a widely used approach is delayed reaction for simplifying multistep reactions. However, recent research results suggest that a delayed reaction with constant time delay is unable to describe multistep reactions accurately. To address this issue, we propose a novel approach using state-dependent time delay to approximate multistep reactions. We first use stochastic simulations to calculate time delay arising from multistep reactions exactly. Then we design algorithms to calculate time delay based on system dynamics precisely. To demonstrate the power of proposed method, two processes of mRNA degradation are used to investigate the function of time delay in determining system dynamics. In addition, a multistep pathway of metabolic synthesis is used to explore the potential of the proposed method to simplify multistep reactions with nonlinear reaction rates. Simulation results suggest that the state-dependent time delay is a promising and accurate approach to reduce model complexity and decrease the number of unknown parameters in the models. PMID:27553753

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

    PubMed Central

    Leite, Fábio P.; Ratcliff, Roger

    2009-01-01

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

  9. Spontaneous Fluctuations in Sensory Processing Predict Within-Subject Reaction Time Variability.

    PubMed

    Ribeiro, Maria J; Paiva, Joana S; Castelo-Branco, Miguel

    2016-01-01

    When engaged in a repetitive task our performance fluctuates from trial-to-trial. In particular, inter-trial reaction time variability has been the subject of considerable research. It has been claimed to be a strong biomarker of attention deficits, increases with frontal dysfunction, and predicts age-related cognitive decline. Thus, rather than being just a consequence of noise in the system, it appears to be under the control of a mechanism that breaks down under certain pathological conditions. Although the underlying mechanism is still an open question, consensual hypotheses are emerging regarding the neural correlates of reaction time inter-trial intra-individual variability. Sensory processing, in particular, has been shown to covary with reaction time, yet the spatio-temporal profile of the moment-to-moment variability in sensory processing is still poorly characterized. The goal of this study was to characterize the intra-individual variability in the time course of single-trial visual evoked potentials and its relationship with inter-trial reaction time variability. For this, we chose to take advantage of the high temporal resolution of the electroencephalogram (EEG) acquired while participants were engaged in a 2-choice reaction time task. We studied the link between single trial event-related potentials (ERPs) and reaction time using two different analyses: (1) time point by time point correlation analyses thereby identifying time windows of interest; and (2) correlation analyses between single trial measures of peak latency and amplitude and reaction time. To improve extraction of single trial ERP measures related with activation of the visual cortex, we used an independent component analysis (ICA) procedure. Our ERP analysis revealed a relationship between the N1 visual evoked potential and reaction time. The earliest time point presenting a significant correlation of its respective amplitude with reaction time occurred 175 ms after stimulus onset

  10. Spontaneous Fluctuations in Sensory Processing Predict Within-Subject Reaction Time Variability

    PubMed Central

    Ribeiro, Maria J.; Paiva, Joana S.; Castelo-Branco, Miguel

    2016-01-01

    When engaged in a repetitive task our performance fluctuates from trial-to-trial. In particular, inter-trial reaction time variability has been the subject of considerable research. It has been claimed to be a strong biomarker of attention deficits, increases with frontal dysfunction, and predicts age-related cognitive decline. Thus, rather than being just a consequence of noise in the system, it appears to be under the control of a mechanism that breaks down under certain pathological conditions. Although the underlying mechanism is still an open question, consensual hypotheses are emerging regarding the neural correlates of reaction time inter-trial intra-individual variability. Sensory processing, in particular, has been shown to covary with reaction time, yet the spatio-temporal profile of the moment-to-moment variability in sensory processing is still poorly characterized. The goal of this study was to characterize the intra-individual variability in the time course of single-trial visual evoked potentials and its relationship with inter-trial reaction time variability. For this, we chose to take advantage of the high temporal resolution of the electroencephalogram (EEG) acquired while participants were engaged in a 2-choice reaction time task. We studied the link between single trial event-related potentials (ERPs) and reaction time using two different analyses: (1) time point by time point correlation analyses thereby identifying time windows of interest; and (2) correlation analyses between single trial measures of peak latency and amplitude and reaction time. To improve extraction of single trial ERP measures related with activation of the visual cortex, we used an independent component analysis (ICA) procedure. Our ERP analysis revealed a relationship between the N1 visual evoked potential and reaction time. The earliest time point presenting a significant correlation of its respective amplitude with reaction time occurred 175 ms after stimulus onset

  11. Spontaneous Fluctuations in Sensory Processing Predict Within-Subject Reaction Time Variability.

    PubMed

    Ribeiro, Maria J; Paiva, Joana S; Castelo-Branco, Miguel

    2016-01-01

    When engaged in a repetitive task our performance fluctuates from trial-to-trial. In particular, inter-trial reaction time variability has been the subject of considerable research. It has been claimed to be a strong biomarker of attention deficits, increases with frontal dysfunction, and predicts age-related cognitive decline. Thus, rather than being just a consequence of noise in the system, it appears to be under the control of a mechanism that breaks down under certain pathological conditions. Although the underlying mechanism is still an open question, consensual hypotheses are emerging regarding the neural correlates of reaction time inter-trial intra-individual variability. Sensory processing, in particular, has been shown to covary with reaction time, yet the spatio-temporal profile of the moment-to-moment variability in sensory processing is still poorly characterized. The goal of this study was to characterize the intra-individual variability in the time course of single-trial visual evoked potentials and its relationship with inter-trial reaction time variability. For this, we chose to take advantage of the high temporal resolution of the electroencephalogram (EEG) acquired while participants were engaged in a 2-choice reaction time task. We studied the link between single trial event-related potentials (ERPs) and reaction time using two different analyses: (1) time point by time point correlation analyses thereby identifying time windows of interest; and (2) correlation analyses between single trial measures of peak latency and amplitude and reaction time. To improve extraction of single trial ERP measures related with activation of the visual cortex, we used an independent component analysis (ICA) procedure. Our ERP analysis revealed a relationship between the N1 visual evoked potential and reaction time. The earliest time point presenting a significant correlation of its respective amplitude with reaction time occurred 175 ms after stimulus onset

  12. Simulation of biochemical reactions with time-dependent rates by the rejection-based algorithm

    SciTech Connect

    Thanh, Vo Hong; Priami, Corrado

    2015-08-07

    We address the problem of simulating biochemical reaction networks with time-dependent rates and propose a new algorithm based on our rejection-based stochastic simulation algorithm (RSSA) [Thanh et al., J. Chem. Phys. 141(13), 134116 (2014)]. The computation for selecting next reaction firings by our time-dependent RSSA (tRSSA) is computationally efficient. Furthermore, the generated trajectory is exact by exploiting the rejection-based mechanism. We benchmark tRSSA on different biological systems with varying forms of reaction rates to demonstrate its applicability and efficiency. We reveal that for nontrivial cases, the selection of reaction firings in existing algorithms introduces approximations because the integration of reaction rates is very computationally demanding and simplifying assumptions are introduced. The selection of the next reaction firing by our approach is easier while preserving the exactness.

  13. Psychological distance and reaction time in a Stroop task.

    PubMed

    De Marchis, Giorgio; Rivero Expósito, María del Prado; Reales Avilés, José Manuel

    2013-11-01

    Several sources of interference may simultaneously affect the onset of the well-known "Stroop effect." Among them is the semantic component, which is reflected in the gradient or semantic effect. This effect consists of an increase in the amount of interference as the semantic distance between the word and the color concept decreases. Shepard (Science 237:1317-1323, 1987) relates psychological space, measured through multidimensional scaling, to mean response times. The present investigation aims to study the function relating the semantic gradient with the psychological distance between the word and the color in a Stroop task. After measuring the gradient, we obtained the subjective rating of the degree of dissimilarity of the gradient words with the concept of "color." In our work, we show that the amount of interference in a Stroop task increases when the semantic distance from the word to the color concept decreases, and it does so exponentially. We replicated the study with different stimuli to test the robustness of the results.

  14. Donders revisited: Discrete or continuous temporal processing underlying reaction time distributions?

    PubMed

    Bao, Yan; Yang, Taoxi; Lin, Xiaoxiong; Pöppel, Ernst

    2016-09-01

    Differences of reaction times to specific stimulus configurations are used as indicators of cognitive processing stages. In this classical experimental paradigm, continuous temporal processing is implicitly assumed. Multimodal response distributions indicate, however, discrete time sampling, which is often masked by experimental conditions. Differences in reaction times reflect discrete temporal mechanisms that are pre-semantically implemented and suggested to be based on entrained neural oscillations.

  15. Donders revisited: Discrete or continuous temporal processing underlying reaction time distributions?

    PubMed

    Bao, Yan; Yang, Taoxi; Lin, Xiaoxiong; Pöppel, Ernst

    2016-09-01

    Differences of reaction times to specific stimulus configurations are used as indicators of cognitive processing stages. In this classical experimental paradigm, continuous temporal processing is implicitly assumed. Multimodal response distributions indicate, however, discrete time sampling, which is often masked by experimental conditions. Differences in reaction times reflect discrete temporal mechanisms that are pre-semantically implemented and suggested to be based on entrained neural oscillations. PMID:27678483

  16. Real time monitoring of accelerated chemical reactions by ultrasonication-assisted spray ionization mass spectrometry.

    PubMed

    Lin, Shu-Hsuan; Lo, Ta-Ju; Kuo, Fang-Yin; Chen, Yu-Chie

    2014-01-01

    Ultrasonication has been used to accelerate chemical reactions. It would be ideal if ultrasonication-assisted chemical reactions could be monitored by suitable detection tools such as mass spectrometry in real time. It would be helpful to clarify reaction intermediates/products and to have a better understanding of reaction mechanism. In this work, we developed a system for ultrasonication-assisted spray ionization mass spectrometry (UASI-MS) with an ~1.7 MHz ultrasonic transducer to monitor chemical reactions in real time. We demonstrated that simply depositing a sample solution on the MHz-based ultrasonic transducer, which was placed in front of the orifice of a mass spectrometer, the analyte signals can be readily detected by the mass spectrometer. Singly and multiply charged ions from small and large molecules, respectively, can be observed in the UASI mass spectra. Furthermore, the ultrasonic transducer used in the UASI setup accelerates the chemical reactions while being monitored via UASI-MS. The feasibility of using this approach for real-time acceleration/monitoring of chemical reactions was demonstrated. The reactions of Girard T reagent and hydroxylamine with steroids were used as the model reactions. Upon the deposition of reactant solutions on the ultrasonic transducer, the intermediate/product ions are readily generated and instantaneously monitored using MS within 1 s. Additionally, we also showed the possibility of using this reactive UASI-MS approach to assist the confirmation of trace steroids from complex urine samples by monitoring the generation of the product ions.

  17. Choice-reaction time to visual motion with varied levels of simultaneous rotary motion

    NASA Technical Reports Server (NTRS)

    Clark, B.; Stewart, J. D.

    1974-01-01

    Twelve airline pilots were studied to determine the effects of whole-body rotation on choice-reaction time to the horizontal motion of a line on a cathode-ray tube. On each trial, one of five levels of visual acceleration and five corresponding proportions of rotary acceleration were presented simultaneously. Reaction time to the visual motion decreased with increasing levels of visual motion and increased with increasing proportions of rotary acceleration. The results conflict with general theories of facilitation during double stimulation but are consistent with neural-clock model of sensory interaction in choice-reaction time.

  18. Visual reaction times during prolonged angular acceleration parallel the subjective perception of rotation

    NASA Technical Reports Server (NTRS)

    Mattson, D. L.

    1975-01-01

    The effect of prolonged angular acceleration on choice reaction time to an accelerating visual stimulus was investigated, with 10 commercial airline pilots serving as subjects. The pattern of reaction times during and following acceleration was compared with the pattern of velocity estimates reported during identical trials. Both reaction times and velocity estimates increased at the onset of acceleration, declined prior to the termination of acceleration, and showed an aftereffect. These results are inconsistent with the torsion-pendulum theory of semicircular canal function and suggest that the vestibular adaptation is of central origin.

  19. Prefrontal D1 dopamine signaling is necessary for temporal expectation during reaction time performance.

    PubMed

    Parker, K L; Alberico, S L; Miller, A D; Narayanan, N S

    2013-01-01

    Responses during a simple reaction time task are influenced by temporal expectation, or the ability to anticipate when a stimulus occurs in time. Here, we test the hypothesis that prefrontal D1 dopamine signaling is necessary for temporal expectation during simple reaction time task performance. We depleted dopamine projections to the medial prefrontal circuits by infusing 6-hydroxidopamine, a selective neurotoxin, into the ventral tegmental area (VTA) of rats, and studied their performance on a simple reaction time task with two delays. VTA dopamine depletion did not change movements or learning of the reaction time task. However, VTA dopamine-depleted animals did not develop delay-dependent speeding of reaction times, suggesting that mesocortical dopamine signaling is required for temporal expectation. Next, we manipulated dopamine signaling within the medial prefrontal cortex using local pharmacology. We found that SCH23390, a D1-type dopamine receptor antagonist, specifically attenuated delay-dependent speeding, while sulpiride, a D2-type receptor antagonist, did not. These data suggest that prefrontal D1 dopamine signaling is necessary for temporal expectation during performance of a simple reaction time task. Our findings provide insight into temporal processing of the prefrontal cortex, and how dopamine signaling influences prefrontal circuits that guide goal-directed behavior. PMID:24120554

  20. Design Factors Affecting the Reaction Time for Identifying Toilet Signs: A Preliminary Study.

    PubMed

    Chen, Yi-Lang; Sie, Cai-Cin

    2016-04-01

    This study focused on the manner in which design factors affect the reaction time for identifying toilet signs. Taiwanese university students and staff members (50 men, 50 women; M age = 23.5 year, SD = 5.7) participated in the study. The 36 toilet signs were modified on three factors (six presenting styles, two figure-ground exchanges, and three colors), and the reaction time data of all participants were collected when the signs were presented in a simulation onscreen. Participants were quickest when reading Chinese text, followed by graphics and English texts. The findings also showed that men and women had different reaction times across various design combinations. These findings can serve as a reference for practically designing toilet signs, since design factors can lead to difficulties with comprehension based on reaction time measurements.

  1. A modified next reaction method for simulating chemical systems with time dependent propensities and delays.

    PubMed

    Anderson, David F

    2007-12-01

    Chemical reaction systems with a low to moderate number of molecules are typically modeled as discrete jump Markov processes. These systems are oftentimes simulated with methods that produce statistically exact sample paths such as the Gillespie algorithm or the next reaction method. In this paper we make explicit use of the fact that the initiation times of the reactions can be represented as the firing times of independent, unit rate Poisson processes with internal times given by integrated propensity functions. Using this representation we derive a modified next reaction method and, in a way that achieves efficiency over existing approaches for exact simulation, extend it to systems with time dependent propensities as well as to systems with delays.

  2. The Effects of Augmented Levels of Stress on Reaction Time in the Peripheral Visual Field

    ERIC Educational Resources Information Center

    Reynolds, Harriet L.

    1976-01-01

    The purpose of this study was to determine if reaction time in the peripheral visual field and size of the functional visual field were altered by augmented levels of physical stress while performing on a bicycle ergometer. (JD)

  3. Effects of d-amphetamine, methaqualone, and phencyclidine on the reaction time of pigeons.

    PubMed

    Kaczor, T; Blakely, E; Poling, A

    1993-06-01

    The effects of acute administrations of d-amphetamine (0.56, 1.0, 1.78, 3.2, and 5.6 mg/kg), methaqualone (5.6, 10, 18, 32, and 56 mg/kg), and phencyclidine (0.3, 0.56, 1.0, and 1.78 mg/kg) on the reaction time of pigeons were examined. In the reaction time assay, birds were trained to depress and hold a foot treadle until a stimulus change occurred. Releases within 2 s of the stimulus change were reinforced with food; premature releases or releases occurring after the 2-s limited hold were not reinforced. At relatively high doses, each of the drugs decreased the percentage of responses that were reinforced. Methaqualone and phencyclidine usually increased median reaction times at these doses, whereas the effects of d-amphetamine on reaction time were less clear.

  4. The Persistence of Solid and Liquid Naive Conceptions: A Reaction Time Study

    NASA Astrophysics Data System (ADS)

    Babai, Reuven; Amsterdamer, Anat

    2008-12-01

    The study explores whether the naive concepts of solid and liquid persist in adolescence. Accuracy of responses and reaction times where measured while 41 ninth graders classified different solids (rigid, non-rigid and powders) and different liquids (runny, dense) into solid or liquid. The results show that these naive conceptions affect adolescences' classifications in terms of both accuracy and reaction time. The rate of correct classifications of non-rigid solids and powders was significantly lower than of rigid solids. Lower rate of success was also found for classification of dense liquids compared with runny liquids. In addition, the reaction time results of correct classifications for non-rigid solids and powders were longer than those for rigid solids and, likewise, reaction times for dense liquids were longer than for runny ones. These results suggest that reasoning processes associated with correct classification of objects that are not consistent with the naive conceptions are more demanding.

  5. Changes of reaction time and blood lactate concentration of elite volleyball players during a game.

    PubMed

    Mroczek, Dariusz; Kawczyński, Adam; Chmura, Jan

    2011-06-01

    The purpose of this study was to investigate changes in reaction time of elite volleyball players during a game. Fourteen volleyball players participated in the study. Reaction time was measured using the Optojump system. In addition, blood lactate concentration was assessed to monitor physiological load during the game. All measurements were performed during a pre-game test and during sets 1, 2, 3 and 4. Reaction time during set 1 decreased significantly by 13,3 % compared with pre-game values, from 600 ms during the pre-game test to 520 ms during set 1 (p<0,05). Blood lactate concentration increased significantly during set 1, 2, 3 and 4 compared with pre-game conditions (p<0,05). Reaction time stays in the first phase of its changes pattern and elite volleyball players do not reach psychomotor fatigue threshold throughout the game. PMID:23487494

  6. Simple eye-hand reaction time in the retinal periphery can be reduced with training.

    PubMed

    Ciuffreda, Kenneth J

    2011-05-01

    One critical aspect of sports vision is eye-hand reaction time, especially for visual stimuli in the retinal periphery. A key question is, "Can eye-hand reaction time be reduced with training?" Evidence from a series of recent experiments suggests that it can. The results in the retinal periphery demonstrated the following: (1) eye-hand reaction time can be reduced by training a small extent (∼10-20 msec) involving central visual processing changes, (2) the training effect transfers to other retinal loci, and (3) the improvement is retained following the cessation of training. These results suggest that training of eye-hand reaction time in the retinal periphery should be considered in athletes to potentially improve their on-field sports performance.

  7. Space and time-resolved probing of heterogeneous catalysis reactions using lab-on-a-chip.

    PubMed

    Navin, Chelliah V; Krishna, Katla Sai; Theegala, Chandra S; Kumar, Challa S S R

    2016-03-14

    Probing catalytic reactions on a catalyst surface in real time is a major challenge. Herein, we demonstrate the utility of a continuous flow millifluidic chip reactor coated with a nanostructured gold catalyst as an effective platform for in situ investigation of the kinetics of catalytic reactions by taking 5-(hydroxymethyl)furfural (HMF) to 2,5-furandicarboxylic acid (FDCA) conversion as a model reaction. The idea conceptualized in this paper can not only dramatically change the ability to probe the time-resolved kinetics of heterogeneous catalysis reactions but also used for investigating other chemical and biological catalytic processes, thereby making this a broad platform for probing reactions as they occur within continuous flow reactors.

  8. [Measuring reaction times in healthy probands before and following a single dose of psychotropic drugs].

    PubMed

    Fischer, W; Streubel, F R; Herzer, H; Rabending, G

    1986-10-01

    A single dose of Clomipramin, 50 mg; Amitriptylin, 50 mg; Desipramin, 50 mg; Imipramin, 50 mg; Diazepam, 10 mg; Carbamazepin, 200 mg; Haloperidol, 3 mg; were each administered orally, and Clomipramin, 25 mg was administered intravenously, and reaction times were measured and compared with those obtained after administering a placebo. The statistical examination was conducted using Wilcoxon's test. In the case of Amitriptylin, Diazepam, and Haloperidol, there was a statistically significant reduction in the reaction times.

  9. A Diffusion Model Explanation of the Worst Performance Rule for Reaction Time and IQ

    ERIC Educational Resources Information Center

    Ratcliff, Roger; Schmiedek, Florian; McKoon, Gail

    2008-01-01

    The worst performance rule for cognitive tasks [Coyle, T.R. (2003). IQ, the worst performance rule, and Spearman's law: A reanalysis and extension. "Intelligence," 31, 567-587] in which reaction time is measured is the result that IQ scores correlate better with longer (i.e., 0.7 and 0.9 quantile) reaction times than shorter (i.e., 0.1 and 0.3…

  10. Real-time data acquisition and alerts may reduce reaction time and improve perfusionist performance during cardiopulmonary bypass.

    PubMed

    Beck, J R; Fung, K; Lopez, H; Mongero, L B; Argenziano, M

    2015-01-01

    Delayed perfusionist identification and reaction to abnormal clinical situations has been reported to contribute to increased mortality and morbidity. The use of automated data acquisition and compliance safety alerts has been widely accepted in many industries and its use may improve operator performance. A study was conducted to evaluate the reaction time of perfusionists with and without the use of compliance alert. A compliance alert is a computer-generated pop-up banner on a pump-mounted computer screen to notify the user of clinical parameters outside of a predetermined range. A proctor monitored and recorded the time from an alert until the perfusionist recognized the parameter was outside the desired range. Group one included 10 cases utilizing compliance alerts. Group 2 included 10 cases with the primary perfusionist blinded to the compliance alerts. In Group 1, 97 compliance alerts were identified and, in group two, 86 alerts were identified. The average reaction time in the group using compliance alerts was 3.6 seconds. The average reaction time in the group not using the alerts was nearly ten times longer than the group using computer-assisted, real-time data feedback. Some believe that real-time computer data acquisition and feedback improves perfusionist performance and may allow clinicians to identify and rectify potentially dangerous situations.

  11. Optimal multisensory decision-making in a reaction-time task

    PubMed Central

    Drugowitsch, Jan; DeAngelis, Gregory C; Klier, Eliana M; Angelaki, Dora E; Pouget, Alexandre

    2014-01-01

    Humans and animals can integrate sensory evidence from various sources to make decisions in a statistically near-optimal manner, provided that the stimulus presentation time is fixed across trials. Little is known about whether optimality is preserved when subjects can choose when to make a decision (reaction-time task), nor when sensory inputs have time-varying reliability. Using a reaction-time version of a visual/vestibular heading discrimination task, we show that behavior is clearly sub-optimal when quantified with traditional optimality metrics that ignore reaction times. We created a computational model that accumulates evidence optimally across both cues and time, and trades off accuracy with decision speed. This model quantitatively explains subjects's choices and reaction times, supporting the hypothesis that subjects do, in fact, accumulate evidence optimally over time and across sensory modalities, even when the reaction time is under the subject's control. DOI: http://dx.doi.org/10.7554/eLife.03005.001 PMID:24929965

  12. Exploiting time-resolved magnetic field effects for determining radical ion reaction rates

    NASA Astrophysics Data System (ADS)

    Bessmertnykh, A. O.; Borovkov, V. I.; Bagryansky, V. A.; Molin, Yu N.

    2016-07-01

    The capabilities of the method of time-resolved magnetic field effect in determining the rates of charge transfer reactions between radical ions and molecules on a nanosecond time scale have been investigated. The approach relies on the electron spin coherence in radical pair's partners generated by ionizing radiation. The spin evolution of the pair is sensitive to the reaction since the latter results in changing magnetic interactions of the unpaired electron. This process can be monitored by magnetic-field-sensitive fluorescence from an irradiated sample that is illustrated using reactions involving alkane radical cations. The accuracy and limitations of the approach are discussed.

  13. Acute physical exercise under hypoxia improves sleep, mood and reaction time.

    PubMed

    de Aquino-Lemos, Valdir; Santos, Ronaldo Vagner T; Antunes, Hanna Karen Moreira; Lira, Fabio S; Luz Bittar, Irene G; Caris, Aline V; Tufik, Sergio; de Mello, Marco Tulio

    2016-02-01

    This study aimed to assess the effect of two sessions of acute physical exercise at 50% VO2peak performed under hypoxia (equivalent to an altitude of 4500 m for 28 h) on sleep, mood and reaction time. Forty healthy men were randomized into 4 groups: Normoxia (NG) (n = 10); Hypoxia (HG) (n = 10); Exercise under Normoxia (ENG) (n = 10); and Exercise under Hypoxia (EHG) (n = 10). All mood and reaction time assessments were performed 40 min after awakening. Sleep was reassessed on the first day at 14 h after the initiation of hypoxia; mood and reaction time were measured 28 h later. Two sessions of acute physical exercise at 50% VO2peak were performed for 60 min on the first and second days after 3 and 27 h, respectively, after starting to hypoxia. Improved sleep efficiency, stage N3 and REM sleep and reduced wake after sleep onset were observed under hypoxia after acute physical exercise. Tension, anger, depressed mood, vigor and reaction time scores improved after exercise under hypoxia. We conclude that hypoxia impairs sleep, reaction time and mood. Acute physical exercise at 50% VO2peak under hypoxia improves sleep efficiency, reversing the aspects that had been adversely affected under hypoxia, possibly contributing to improved mood and reaction time.

  14. Effects of Arm Ergometry Exercise on the Reaction, Movement and Response Times of the Lower Extremities.

    ERIC Educational Resources Information Center

    Israel, Richard G.

    A study determined the effects of fatigue produced in the upper extremities on the reaction time, movement time, and response time of the lower extremities in 30 male subjects, 19-25 years old. Each subject participated in a 10 trial practice session one day prior to the experiment and immediately preceding the pre-test. The pre-test consisted of…

  15. Differences in psychomotor reaction time in male monozygotic twins discordant for lifetime cigarette smoking.

    PubMed

    Gibbons, L E; Simonen, R L; Videman, T; Battié, M C

    1996-12-01

    The effects of long-term cigarette smoking on psychomotor reaction time were investigated among 8 pairs of monozygotic male twins highly discordant for lifetime smoking (means 32.4 versus 0.6 pack-years). The men had no diagnosed cardiovascular disease or other major diseases, musculoskeletal complaints, or vision problems that might interfere with reaction time testing. The twins had similar education, work, and exercise histories; alcohol and coffee consumption and exposure to solvents were examined as possible confounds. Direct comparison of cotwins also controlled for age, genetics, and possible early environmental factors. Simple and choice reaction time were measured in the dominant hand and in both feet. The decision-time component of total reaction time was of primary interest. On average, long-term smokers had slower decision times than their nonsmoking twins; however, the differences were small (5 to 14%) and were not statistically significant for four of the six decision-time measures, perhaps due to the lack of power with only eight twin pairs. Further study may confirm our evidence suggesting that long-term cigarette smoking impedes reaction time, a key measure of function of the central nervous system.

  16. Unimolecular diffusion-mediated reactions with a nonrandom time-modulated absorbing barrier

    NASA Technical Reports Server (NTRS)

    Bashford, D.; Weaver, D. L.

    1986-01-01

    A diffusion-reaction model with time-dependent reactivity is formulated and applied to unimolecular reactions. The model is solved exactly numerically and approximately analytically for the unreacted fraction as a function of time. It is shown that the approximate analytical solution is valid even when the system is far from equilibrium, and when the reactivity probability is more complicated than a square-wave function of time. A discussion is also given of an approach to problems of this type using a stochastically fluctuating reactivity, and the first-passage time for a particular example is derived.

  17. Chemical kinetic analysis of hydrogen-air ignition and reaction times

    NASA Technical Reports Server (NTRS)

    Rogers, R. C.; Schexnayder, C. J., Jr.

    1981-01-01

    An anaytical study of hydrogen air kinetics was performed. Calculations were made over a range of pressure from 0.2 to 4.0 atm, temperatures from 850 to 2000 K, and mixture equivalence ratios from 0.2 to 2.0. The finite rate chemistry model included 60 reactions in 20 species of the H2-O2-N2 system. The calculations also included an assessment of how small amounts of the chemicals H2O, NOx, H2O2, and O3 in the initial mixture affect ignition and reaction times, and how the variation of the third body efficiency of H2O relative of N2 in certain key reactions may affect reaction time. The results indicate that for mixture equivalence ratios between 0.5 and 1.7, ignition times are nearly constant; however, the presence of H2O and NO can have significant effects on ignition times, depending on the mixture temperature. Reaction time is dominantly influenced by pressure but is nearly independent of initial temperature, equivalence ratio, and the addition of chemicals. Effects of kinetics on reaction at supersonic combustor conditions are discussed.

  18. Real-time reaction monitoring by ultrafast 2D NMR on a benchtop spectrometer.

    PubMed

    Gouilleux, Boris; Charrier, Benoît; Danieli, Ernesto; Dumez, Jean-Nicolas; Akoka, Serge; Felpin, François-Xavier; Rodriguez-Zubiri, Mireia; Giraudeau, Patrick

    2015-12-01

    Reaction monitoring is widely used to follow chemical processes in a broad range of application fields. Recently, the development of robust benchtop NMR spectrometers has brought NMR under the fume hood, making it possible to monitor chemical reactions in a safe and accessible environment. However, these low-field NMR approaches suffer from limited resolution leading to strong peak overlaps, which can limit their application range. Here, we propose an approach capable of recording ultrafast 2D NMR spectra on a compact spectrometer and of following in real time reactions in the synthetic chemistry laboratory. This approach--whose potential is shown here on a Heck-Matsuda reaction--is highly versatile; the duration of the measurement can be optimized to follow reactions whose time scale ranges from between a few tens of seconds to a few hours. It makes it possible to monitor complex reactions in non-deuterated solvents, and to confirm in real time the molecular structure of the compounds involved in the reaction while giving access to relevant kinetic parameters.

  19. Practice Effects Associated With Repeated Assessment of a Clinical Test of Reaction Time

    PubMed Central

    Del Rossi, Gianluca; Malaguti, Alfonso; Del Rossi, Samanta

    2014-01-01

    Context: Researchers have confirmed that the ruler-drop test could be included as part of a multifaceted concussion-assessment battery and potentially as a way to track recovery from head injury. However, it is unclear if this clinical test of reaction time would be characterized by inconsistent performance because of practice effects. Objective: To determine if the ruler-drop test is susceptible to practice effects after serial administration. Design: Descriptive laboratory study. Setting: Sports medicine research laboratory. Patients or Other Participants: Forty-three persons (age = 21.8 ± 2.6 years). Intervention(s): Ten sessions were completed over 5 weeks. Participants completed 10 trials of the ruler-drop test during each session. Main Outcome Measure(s): The mean reaction times calculated for all participants from each test session were analyzed to determine if there was any meaningful change (ie, improvement) in reaction time over the course of the investigation. Results: Simple reaction time improved (ie, decreased) after repeated administration of the ruler-drop test, and the most pronounced improvement occurred between the first 2 test sessions. Between the first and second test sessions, reaction time decreased by almost 7 milliseconds, and there was an overall improvement of almost 13 milliseconds between the first and tenth sessions. Although the pairwise comparisons between the first and second and the first and third sessions were not significant, the change in mean reaction time between the first session and most of the other sessions was significant. We noted no differences when successive sessions were compared. Conclusions: To prevent practice-related improvements in reaction time, practitioners should allow at least 1 practice session before recording baseline results on the ruler-drop test. PMID:24673236

  20. Laboratory real-time and in situ monitoring of mechanochemical milling reactions by Raman spectroscopy.

    PubMed

    Gracin, Davor; Štrukil, Vjekoslav; Friščić, Tomislav; Halasz, Ivan; Užarević, Krunoslav

    2014-06-10

    Mechanistic understanding of mechanochemical reactions is sparse and has been acquired mostly by stepwise ex situ analysis. We describe herein an unprecedented laboratory technique to monitor the course of mechanochemical transformations at the molecular level in situ and in real time by using Raman spectroscopy. The technique, in which translucent milling vessels are used that enable the collection of a Raman scattering signal from the sample as it is being milled, was validated on mechanochemical reactions to form coordination polymers and organic cocrystals. The technique enabled the assessment of the reaction dynamics and course under different reaction conditions as well as, for the first time, direct insight into the behavior of liquid additives during liquid-assisted grinding.

  1. Adverse reactions to iodinated contrast media administered at the time of endoscopic retrograde cholangiopancreatography (ERCP).

    PubMed

    Pan, Jen-Jung; Draganov, Peter V

    2009-03-01

    Adverse reactions after intravascular administration of iodine contrast media are common and prophylactic regiments consisting of the use of steroids and low osmolality contrast media are highly effective in significantly decreasing the adverse reactions rate. The same type of contrast media are also used for opacification of the biliary tree and the pancreatic duct at the time of endoscopic retrograde cholangiopancreatography (ERCP). Systemic absorption of contrast media after ERCP routinely occurs. Although the adverse reaction rate appears to be very low the exact incidence remains unknown due to the retrospective nature of all reports. Despite the lack of formal recommendations, numerous prophylactic regiments are routinely used prior to ERCP in patients with history of prior reaction to intravascular contrast media. Moreover, the use of prophylaxis has even expanded to patients with no prior reaction to intravascular contrast media who are somehow perceived to be at increase risk (e.g. shellfish allergy). Recently, the first large scale prospective study reported exceedingly low incidence of adverse reaction to high oslmolality iodine-containing contrast media administered at the time of ERCP done without prophylactic premedication even in patients considered to be at the highest risk (prior severe reaction to intravascular contrast media administration). These data suggest that the use of prophylactic regiments prior to ERCP appears to be unnecessary.

  2. Choice reaction time to visual motion during prolonged rotary motion in airline pilots

    NASA Technical Reports Server (NTRS)

    Stewart, J. D.; Clark, B.

    1975-01-01

    Thirteen airline pilots were studied to determine the effect of preceding rotary accelerations on the choice reaction time to the horizontal acceleration of a vertical line on a cathode-ray tube. On each trial, one of three levels of rotary and visual acceleration was presented with the rotary stimulus preceding the visual by one of seven periods. The two accelerations were always equal and were presented in the same or opposite directions. The reaction time was found to increase with increases in the time the rotary acceleration preceded the visual acceleration, and to decrease with increased levels of visual and rotary acceleration. The reaction time was found to be shorter when the accelerations were in the same direction than when they were in opposite directions. These results suggest that these findings are a special case of a general effect that the authors have termed 'gyrovisual modulation'.

  3. Effect of reaction temperature and time on the electrochemical properties of nickel hydroxide nanosheets

    NASA Astrophysics Data System (ADS)

    Li, Zijiong; Zhang, Weiyang; Su, Yuling; Wang, Haiyan; Yang, Baocheng

    2016-10-01

    2D (Two-dimensional) Ni(OH)2 nanosheets is synthesized by hydrothermal method with nickel nitrate hexahydrate and hexamethylenetetramine as raw materials. Herein, the effect of reaction temperature and time on the electrochemical performance of Ni(OH)2 nanosheets are studied. The results showed that morphology and performance appeared great changes as the reaction time and temperature changed. The maximum specific capacitance of 1404.6 F g-1 at current density of 1.5 A g-1 by chronopotentiometry is achieved for Ni(OH)2 nanosheets in 6.0 M KOH when reaction temperature and time are 140 °C and 8 h. Moreover, the capacitance only reduced to 88% after 2000 times charge and discharge of constant current. Such results demonstrated that Ni(OH)2 nanosheets is a promising electrode material for the practical application of high-performance supercapacitor and it is worthy of further investigation.

  4. Time-resolved FTIR emission studies of laser photofragmentation and radical reactions

    SciTech Connect

    Leone, S.R.

    1993-12-01

    Recent studies have focused specifically on collision processes, such as single collision energy transfer, reaction dynamics, and radical reactions. The authors employ novel FTIR techniques in the study of single collision energy transfer processes using translationally fast H atom, as well as radical-radical reactions, e.g. CH{sub 3} + O, CF{sub 3} + H(D), and Cl + C{sub 2}H{sub 5}. The fast atoms permit unique high energy regions of certain transition states of combustion species to be probed for the first time.

  5. The mineralogic evolution of the Martian surface through time: Implications from chemical reaction path modeling studies

    NASA Technical Reports Server (NTRS)

    Plumlee, G. S.; Ridley, W. I.; Debraal, J. D.; Reed, M. H.

    1993-01-01

    Chemical reaction path calculations were used to model the minerals that might have formed at or near the Martian surface as a result of volcano or meteorite impact driven hydrothermal systems; weathering at the Martian surface during an early warm, wet climate; and near-zero or sub-zero C brine-regolith reactions in the current cold climate. Although the chemical reaction path calculations carried out do not define the exact mineralogical evolution of the Martian surface over time, they do place valuable geochemical constraints on the types of minerals that formed from an aqueous phase under various surficial and geochemically complex conditions.

  6. Direct picosecond time resolution of unimolecular reactions initiated by local mode excitation

    NASA Technical Reports Server (NTRS)

    Scherer, N. F.; Doany, F. E.; Zewail, A. H.; Perry, J. W.

    1986-01-01

    Attention is given to the first results of direct, picosec measurements of the Delta-nu(OH) 5 local mode transition of H2O2. These time-resolved studies yield a direct measure of the unimolecular dissociation rate, and furnish a lower limit for the rate of energy redistribution from the OH stretch to the O-O reaction coordinate. The data thus determined may be used to ascertain the domain of validity for statistical unimolecular reaction rate theories.

  7. A Flow-Through Reaction Cell that Couples Time - Resolved Analysis

    SciTech Connect

    A Wall; P Heaney; R Mathur; J Post; J Hanson; P Eng

    2011-12-31

    A non-metallic flow-through reaction cell is described, designed for in situ time-resolved X-ray diffraction coupled with stable isotope analysis. The experimental setup allows the correlation of Cu isotope fractionation with changes in crystal structure during copper sulfide dissolution. This flow-through cell can be applied to many classes of fluid-mineral reactions that involve dissolution or ion exchange.

  8. Immediate effects of different treatments for the wrist joints of subdominant hands, using electromechanical reaction time.

    PubMed

    Hu, Chunying; Huang, Qiuchen; Yu, Lili; Zhou, Yue; Gu, Rui; Cui, Yao; Ge, Meng; Xu, Yanfeng; Liu, Jianfeng

    2016-08-01

    [Purpose] The aim of this study was to examine the immediate effects of muscle strength training and neuromuscular joint facilitation distal resistance training on wrist joints by using electromechanical reaction time. [Subjects and Methods] The subjects were 12 healthy young people (24.2 ± 3.1 years, 169.7 ± 6.5 cm, 65.3 ± 12.6 kg). Two kinds of isotonic contraction techniques were applied on the wrist joint: the wrist joint extension muscle strength training and the wrist joint extension pattern of neuromuscular joint facilitation. The electromechanical reaction time, premotor time, and motor time of the left upper limb were measured before and after each intervention session of muscle strength training and neuromuscular joint facilitation. [Results] The neuromuscular joint facilitation group showed significant shortening of the electromechanical reaction time and motor time after the intervention. [Conclusion] These results suggest that the electromechanical reaction time and motor time of the wrist joint can be improved by neuromuscular joint facilitation together with proximal resistance training, which can be used as a new form of exercise for improving the functions of subdominant hand wrist joints.

  9. Immediate effects of different treatments for the wrist joints of subdominant hands, using electromechanical reaction time

    PubMed Central

    Hu, Chunying; Huang, Qiuchen; Yu, Lili; Zhou, Yue; Gu, Rui; Cui, Yao; Ge, Meng; Xu, Yanfeng; Liu, Jianfeng

    2016-01-01

    [Purpose] The aim of this study was to examine the immediate effects of muscle strength training and neuromuscular joint facilitation distal resistance training on wrist joints by using electromechanical reaction time. [Subjects and Methods] The subjects were 12 healthy young people (24.2 ± 3.1 years, 169.7 ± 6.5 cm, 65.3 ± 12.6 kg). Two kinds of isotonic contraction techniques were applied on the wrist joint: the wrist joint extension muscle strength training and the wrist joint extension pattern of neuromuscular joint facilitation. The electromechanical reaction time, premotor time, and motor time of the left upper limb were measured before and after each intervention session of muscle strength training and neuromuscular joint facilitation. [Results] The neuromuscular joint facilitation group showed significant shortening of the electromechanical reaction time and motor time after the intervention. [Conclusion] These results suggest that the electromechanical reaction time and motor time of the wrist joint can be improved by neuromuscular joint facilitation together with proximal resistance training, which can be used as a new form of exercise for improving the functions of subdominant hand wrist joints.

  10. Immediate effects of different treatments for the wrist joints of subdominant hands, using electromechanical reaction time.

    PubMed

    Hu, Chunying; Huang, Qiuchen; Yu, Lili; Zhou, Yue; Gu, Rui; Cui, Yao; Ge, Meng; Xu, Yanfeng; Liu, Jianfeng

    2016-08-01

    [Purpose] The aim of this study was to examine the immediate effects of muscle strength training and neuromuscular joint facilitation distal resistance training on wrist joints by using electromechanical reaction time. [Subjects and Methods] The subjects were 12 healthy young people (24.2 ± 3.1 years, 169.7 ± 6.5 cm, 65.3 ± 12.6 kg). Two kinds of isotonic contraction techniques were applied on the wrist joint: the wrist joint extension muscle strength training and the wrist joint extension pattern of neuromuscular joint facilitation. The electromechanical reaction time, premotor time, and motor time of the left upper limb were measured before and after each intervention session of muscle strength training and neuromuscular joint facilitation. [Results] The neuromuscular joint facilitation group showed significant shortening of the electromechanical reaction time and motor time after the intervention. [Conclusion] These results suggest that the electromechanical reaction time and motor time of the wrist joint can be improved by neuromuscular joint facilitation together with proximal resistance training, which can be used as a new form of exercise for improving the functions of subdominant hand wrist joints. PMID:27630442

  11. Intra-Individual Reaction Time Variability in Schizophrenia, Depression and Borderline Personality Disorder

    ERIC Educational Resources Information Center

    Kaiser, Stefan; Roth, Alexander; Rentrop, Mirjam; Friederich, Hans-Christoph; Bender, Stephan; Weisbrod, Matthias

    2008-01-01

    Intra-individual reaction time variability (IIV) in neuropsychological task performance reflects short term fluctuations in performance. Increased IIV has been reported in patients with schizophrenia and could be related to a deficient neural timing mechanism, but the role of IIV in adult patients with other psychiatric disorders has not been…

  12. Immediate effects of different treatments for the wrist joints of subdominant hands, using electromechanical reaction time

    PubMed Central

    Hu, Chunying; Huang, Qiuchen; Yu, Lili; Zhou, Yue; Gu, Rui; Cui, Yao; Ge, Meng; Xu, Yanfeng; Liu, Jianfeng

    2016-01-01

    [Purpose] The aim of this study was to examine the immediate effects of muscle strength training and neuromuscular joint facilitation distal resistance training on wrist joints by using electromechanical reaction time. [Subjects and Methods] The subjects were 12 healthy young people (24.2 ± 3.1 years, 169.7 ± 6.5 cm, 65.3 ± 12.6 kg). Two kinds of isotonic contraction techniques were applied on the wrist joint: the wrist joint extension muscle strength training and the wrist joint extension pattern of neuromuscular joint facilitation. The electromechanical reaction time, premotor time, and motor time of the left upper limb were measured before and after each intervention session of muscle strength training and neuromuscular joint facilitation. [Results] The neuromuscular joint facilitation group showed significant shortening of the electromechanical reaction time and motor time after the intervention. [Conclusion] These results suggest that the electromechanical reaction time and motor time of the wrist joint can be improved by neuromuscular joint facilitation together with proximal resistance training, which can be used as a new form of exercise for improving the functions of subdominant hand wrist joints. PMID:27630442

  13. Relative performance of the two hands in simple and choice reaction time tasks

    PubMed Central

    Nisiyama, M.; Ribeiro-do-Valle, L.E.

    2014-01-01

    There is evidence that the left hemisphere is more competent for motor control than the right hemisphere. This study investigated whether this hemispheric asymmetry is expressed in the latency/duration of sequential responses performed by the left and/or right hands. Thirty-two right-handed young adults (16 males, 16 females; 18-25 years old) were tested in a simple or choice reaction time task. They responded to a left and/or right visual target by moving their left and/or right middle fingers between two keys on each side of the midline. Right hand reaction time did not differ from left hand reaction time. Submovement times were longer for the right hand than the left hand when the response was bilateral. Pause times were shorter for the right hand than the left hand, both when the responses were unilateral or bilateral. Reaction time results indicate that the putatively more efficient response preparation by the left hemisphere motor mechanisms is not expressed behaviorally. Submovement time and pause time results indicate that the putatively more efficient response execution by the left hemisphere motor mechanisms is expressed behaviorally. In the case of the submovements, the less efficient motor control of the left hand would be compensated by a more intense attention to this hand. PMID:24345871

  14. Reaction time variability associated with reading skills in poor readers with ADHD.

    PubMed

    Tamm, Leanne; Epstein, Jeffery N; Denton, Carolyn A; Vaughn, Aaron J; Peugh, James; Willcutt, Erik G

    2014-03-01

    Linkages between neuropsychological functioning (i.e., response inhibition, processing speed, reaction time variability) and word reading have been documented among children with attention-deficit/hyperactivity disorder (ADHD) and children with Reading Disorders. However, associations between neuropsychological functioning and other aspects of reading (i.e., fluency, comprehension) have not been well-documented among children with comorbid ADHD and Reading Disorder. Children with ADHD and poor word reading (i.e., ≤25th percentile) completed a stop signal task (SST) and tests of word reading, reading fluency, and reading comprehension. Multivariate multiple regression was conducted predicting the reading skills from SST variables [i.e., mean reaction time (MRT), reaction time standard deviation (SDRT), and stop signal reaction time (SSRT)]. SDRT predicted word reading, reading fluency, and reading comprehension. MRT and SSRT were not associated with any reading skill. After including word reading in models predicting reading fluency and reading comprehension, the effects of SDRT were minimized. Reaction time variability (i.e., SDRT) reflects impairments in information processing and failure to maintain executive control. The pattern of results from this study suggest SDRT exerts its effects on reading fluency and reading comprehension through its effect on word reading (i.e., decoding) and that this relation may be related to observed deficits in higher-level elements of reading.

  15. The Relationship between Cellular Phone Use, Performance, and Reaction Time among College Students: Implications for Cellular Phone Use while Driving

    ERIC Educational Resources Information Center

    Szyfman, Adam; Wanner, Gregory; Spencer, Leslie

    2003-01-01

    Two studies were performed to determine the relationship between cellular phone use and either reaction time or performance among college students. In the first study 60 undergraduates completed a computerized reaction time test. Mean reaction times were significantly higher when participants were talking on a cellular phone, either handheld or on…

  16. Caffeine reduces reaction time and improves performance in simulated-contest of taekwondo.

    PubMed

    Santos, Victor G F; Santos, Vander R F; Felippe, Leandro J C; Almeida, Jose W; Bertuzzi, Rômulo; Kiss, Maria A P D M; Lima-Silva, Adriano E

    2014-02-10

    The aim of this study was to investigate the effects of caffeine on reaction time during a specific taekwondo task and athletic performance during a simulated taekwondo contest. Ten taekwondo athletes ingested either 5 mg·kg⁻¹ body mass caffeine or placebo and performed two combats (spaced apart by 20 min). The reaction-time test (five kicks "Bandal Tchagui") was performed immediately prior to the first combat and immediately after the first and second combats. Caffeine improved reaction time (from 0.42 ± 0.05 to 0.37 ± 0.07 s) only prior to the first combat (P = 0.004). During the first combat, break times during the first two rounds were shorter in caffeine ingestion, followed by higher plasma lactate concentrations compared with placebo (P = 0.029 and 0.014, respectively). During the second combat, skipping-time was reduced, and relative attack times and attack/skipping ratio was increased following ingestion of caffeine during the first two rounds (all P < 0.05). Caffeine resulted in no change in combat intensity parameters between the first and second combat (all P > 0.05), but combat intensity was decreased following placebo (all P < 0.05). In conclusion, caffeine reduced reaction time in non-fatigued conditions and delayed fatigue during successive taekwondo combats.

  17. Caffeine reduces reaction time and improves performance in simulated-contest of taekwondo.

    PubMed

    Santos, Victor G F; Santos, Vander R F; Felippe, Leandro J C; Almeida, Jose W; Bertuzzi, Rômulo; Kiss, Maria A P D M; Lima-Silva, Adriano E

    2014-01-01

    The aim of this study was to investigate the effects of caffeine on reaction time during a specific taekwondo task and athletic performance during a simulated taekwondo contest. Ten taekwondo athletes ingested either 5 mg·kg⁻¹ body mass caffeine or placebo and performed two combats (spaced apart by 20 min). The reaction-time test (five kicks "Bandal Tchagui") was performed immediately prior to the first combat and immediately after the first and second combats. Caffeine improved reaction time (from 0.42 ± 0.05 to 0.37 ± 0.07 s) only prior to the first combat (P = 0.004). During the first combat, break times during the first two rounds were shorter in caffeine ingestion, followed by higher plasma lactate concentrations compared with placebo (P = 0.029 and 0.014, respectively). During the second combat, skipping-time was reduced, and relative attack times and attack/skipping ratio was increased following ingestion of caffeine during the first two rounds (all P < 0.05). Caffeine resulted in no change in combat intensity parameters between the first and second combat (all P > 0.05), but combat intensity was decreased following placebo (all P < 0.05). In conclusion, caffeine reduced reaction time in non-fatigued conditions and delayed fatigue during successive taekwondo combats. PMID:24518826

  18. QRTEngine: An easy solution for running online reaction time experiments using Qualtrics.

    PubMed

    Barnhoorn, Jonathan S; Haasnoot, Erwin; Bocanegra, Bruno R; van Steenbergen, Henk

    2015-12-01

    Performing online behavioral research is gaining increased popularity among researchers in psychological and cognitive science. However, the currently available methods for conducting online reaction time experiments are often complicated and typically require advanced technical skills. In this article, we introduce the Qualtrics Reaction Time Engine (QRTEngine), an open-source JavaScript engine that can be embedded in the online survey development environment Qualtrics. The QRTEngine can be used to easily develop browser-based online reaction time experiments with accurate timing within current browser capabilities, and it requires only minimal programming skills. After introducing the QRTEngine, we briefly discuss how to create and distribute a Stroop task. Next, we describe a study in which we investigated the timing accuracy of the engine under different processor loads using external chronometry. Finally, we show that the QRTEngine can be used to reproduce classic behavioral effects in three reaction time paradigms: a Stroop task, an attentional blink task, and a masked-priming task. These findings demonstrate that QRTEngine can be used as a tool for conducting online behavioral research even when this requires accurate stimulus presentation times.

  19. Caffeine Reduces Reaction Time and Improves Performance in Simulated-Contest of Taekwondo

    PubMed Central

    Santos, Victor G. F.; Santos, Vander R. F.; Felippe, Leandro J. C.; Almeida, Jose W.; Bertuzzi, Rômulo; Kiss, Maria A. P. D. M.; Lima-Silva, Adriano E.

    2014-01-01

    The aim of this study was to investigate the effects of caffeine on reaction time during a specific taekwondo task and athletic performance during a simulated taekwondo contest. Ten taekwondo athletes ingested either 5 mg·kg−1 body mass caffeine or placebo and performed two combats (spaced apart by 20 min). The reaction-time test (five kicks “Bandal Tchagui”) was performed immediately prior to the first combat and immediately after the first and second combats. Caffeine improved reaction time (from 0.42 ± 0.05 to 0.37 ± 0.07 s) only prior to the first combat (P = 0.004). During the first combat, break times during the first two rounds were shorter in caffeine ingestion, followed by higher plasma lactate concentrations compared with placebo (P = 0.029 and 0.014, respectively). During the second combat, skipping-time was reduced, and relative attack times and attack/skipping ratio was increased following ingestion of caffeine during the first two rounds (all P < 0.05). Caffeine resulted in no change in combat intensity parameters between the first and second combat (all P > 0.05), but combat intensity was decreased following placebo (all P < 0.05). In conclusion, caffeine reduced reaction time in non-fatigued conditions and delayed fatigue during successive taekwondo combats. PMID:24518826

  20. Visual reaction times may be improved by certain beta-blockers.

    PubMed

    Harms, D

    1985-01-01

    The effects of the beta-blocker atenolol on vigilance, concentration, and psychophysiological condition were determined by measuring visual reaction time and choice reaction time in volunteers subjected to combined physical and mental stress. Atenolol 50 mg or placebo were administered for three days in a double-blind crossover design. Forty male subjects aged 26 +/- 6 years with a mean blood pressure of 126/79 mmHg and increased activity of the sympatheticus nerve were admitted to the first study. Physical workload was imposed using a training ergometer for ten minutes and mental workload was introduced by asking the subjects to calculate additions and subtractions on mechanical equipment. Electrooculography was used to measure visual reaction time. Fifty subjects aged 32 +/- 9 years with a mean blood pressure of 141/90 mmHg were admitted to a second study. The same crossover design was followed, but a different mental workload was imposed; subjects were required to respond to coloured light signals which were presented at intervals of 0.8 seconds, by pressing the appropriate buttons. In this second study visual reaction time was also assessed by electrooculography whereas choice reaction time was defined as the time between the lighting of a signal (in one of five colours on 1-25 different places on a screen) and its extinction by pressing an appropriate coloured button. As expected, blood pressure and heart rate decreased with atenolol. In the first study, in both periods, visual reaction time was higher with placebo than with atenolol. The effect of treatment was small but highly significant (p = 0.004).(ABSTRACT TRUNCATED AT 250 WORDS)

  1. Time-resolved tryptophan fluorescence in photosynthetic reaction centers from Rhodobacter sphaeroides

    NASA Technical Reports Server (NTRS)

    Godik, V. I.; Blankenship, R. E.; Causgrove, T. P.; Woodbury, N.

    1993-01-01

    Tryptophan fluorescence of reaction centers isolated from Rhodobacter sphaeroides, both stationary and time-resolved, was studied. Fluorescence kinetics were found to fit best a sum of four discrete exponential components. Half of the initial amplitude was due to a component with a lifetime of congruent to 60 ps, belonging to Trp residues, capable of efficient transfer of excitation energy to bacteriochlorophyll molecules of the reaction center. The three other components seem to be emitted by Trp ground-state conformers, unable to participate in such a transfer. Under the influence of intense actinic light, photooxidizing the reaction centers, the yield of stationary fluorescence diminished by congruent to 1.5 times, while the number of the kinetic components and their life times remained practically unchanged. Possible implications of the observed effects for the primary photosynthesis events are considered.

  2. Quantitation of viral load by real-time PCR-monitoring Invader reaction.

    PubMed

    Tadokoro, Kenichi; Yamaguchi, Toshikazu; Egashira, Toru; Hara, Takashi

    2009-02-01

    With its broad effective range for fluorescence detection, real-time PCR is one of the most valuable techniques for quantitation in molecular biology. A modified real-time PCR assay is described for determining viral load. The assay uses fluorescence to measure the number of PCR amplicons by monitoring the Invader reaction in four steps in the thermal cycle. The Invader reaction with its cleavase was performed at moderate temperature after the amplicon was denatured at a high temperature. The method was as effective as real-time PCR with a TaqMan probe in determining the quantity of virus in samples of human papillomavirus type 16. Importantly, the assay allows the use of a common probe for multiple reactions. Thus, this method is a rapid inexpensive assay with a common fluorescence probe that does not depend on the conformation of the target DNAs. PMID:19014973

  3. Sex differences in relations of muscle power, lung function, and reaction time in athletes.

    PubMed

    Gursoy, Recep

    2010-06-01

    In an earlier study, relations of nonverbal abilities with several bodily measures such as height, weight, and lung capacity were observed. The present aim was estimation of associations of muscle power and lung function with simple eye-hand reaction time. Sex differences for muscle power were significant even with the covariates of height, weight, and age included; however, these disappeared for lung functions (forced vital capacity and peak expiratory flow) and reaction time. The effects of leg power, forced vital capacity, and peak expiratory flow on the left eye-hand reaction time were significant after adjustment for height, weight, right- and left-hand powers and age. The positive effect of exercise may be especially associated with the right brain activity or left hand speed.

  4. Effect of intermittent exercise on multiple-choice reaction times of soccer players.

    PubMed

    Lemmink, Koen A P M; Visscher, Chris

    2005-02-01

    The influence of intermittent exercise on a choice-response time task was investigated. Two groups of 8 male soccer players (M age = 20.9, SD = 2.0) participated. They spent 4.4 (SD = 1.3) weekly hours on soccer training and had been playing soccer for 13 (SD = 3.3) years. Multiple-choice reaction speed and response accuracy were measured four times. Between measurements, one group performed 8-min. blocks of intermittent exercise on a bicycle ergometer and one group rested. Analysis showed that reaction speed and response accuracy were not significantly different between the two groups. Furthermore, there were significant faster reaction times and a larger number of correct reactions through Block 2 in both the exercise and control group (p < .05), probably a result of learning processes and familiarization with the task procedures. Further research towards the specific influence of mode of exercise, intensity, work-rest ratio and duration of intermittent exercise, and the sensitivity of reaction time tasks will be necessary to clarify the relationship between intermittent exercise and cognitive performance.

  5. Estimating Reaction Rate Coefficients Within a Travel-Time Modeling Framework

    SciTech Connect

    Gong, R; Lu, C; Luo, Jian; Wu, Wei-min; Cheng, H.; Criddle, Craig; Kitanidis, Peter K.; Gu, Baohua; Watson, David B; Jardine, Philip M; Brooks, Scott C

    2011-03-01

    A generalized, efficient, and practical approach based on the travel-time modeling framework is developed to estimate in situ reaction rate coefficients for groundwater remediation in heterogeneous aquifers. The required information for this approach can be obtained by conducting tracer tests with injection of a mixture of conservative and reactive tracers and measurements of both breakthrough curves (BTCs). The conservative BTC is used to infer the travel-time distribution from the injection point to the observation point. For advection-dominant reactive transport with well-mixed reactive species and a constant travel-time distribution, the reactive BTC is obtained by integrating the solutions to advective-reactive transport over the entire travel-time distribution, and then is used in optimization to determine the in situ reaction rate coefficients. By directly working on the conservative and reactive BTCs, this approach avoids costly aquifer characterization and improves the estimation for transport in heterogeneous aquifers which may not be sufficiently described by traditional mechanistic transport models with constant transport parameters. Simplified schemes are proposed for reactive transport with zero-, first-, nth-order, and Michaelis-Menten reactions. The proposed approach is validated by a reactive transport case in a two-dimensional synthetic heterogeneous aquifer and a field-scale bioremediation experiment conducted at Oak Ridge, Tennessee. The field application indicates that ethanol degradation for U(VI)-bioremediation is better approximated by zero-order reaction kinetics than first-order reaction kinetics.

  6. Estimating reaction rate coefficients within a travel-time modeling framework.

    PubMed

    Gong, R; Lu, C; Wu, W-M; Cheng, H; Gu, B; Watson, D; Jardine, P M; Brooks, S C; Criddle, C S; Kitanidis, P K; Luo, J

    2011-01-01

    A generalized, efficient, and practical approach based on the travel-time modeling framework is developed to estimate in situ reaction rate coefficients for groundwater remediation in heterogeneous aquifers. The required information for this approach can be obtained by conducting tracer tests with injection of a mixture of conservative and reactive tracers and measurements of both breakthrough curves (BTCs). The conservative BTC is used to infer the travel-time distribution from the injection point to the observation point. For advection-dominant reactive transport with well-mixed reactive species and a constant travel-time distribution, the reactive BTC is obtained by integrating the solutions to advective-reactive transport over the entire travel-time distribution, and then is used in optimization to determine the in situ reaction rate coefficients. By directly working on the conservative and reactive BTCs, this approach avoids costly aquifer characterization and improves the estimation for transport in heterogeneous aquifers which may not be sufficiently described by traditional mechanistic transport models with constant transport parameters. Simplified schemes are proposed for reactive transport with zero-, first-, nth-order, and Michaelis-Menten reactions. The proposed approach is validated by a reactive transport case in a two-dimensional synthetic heterogeneous aquifer and a field-scale bioremediation experiment conducted at Oak Ridge, Tennessee. The field application indicates that ethanol degradation for U(VI)-bioremediation is better approximated by zero-order reaction kinetics than first-order reaction kinetics.

  7. Chronic stroke and aging: the impact of acoustic stimulus intensity on fractionated reaction time.

    PubMed

    Coombes, Stephen A; Janelle, Christopher M; Cauraugh, James H

    2009-03-13

    In control samples, intense acoustic "go" stimuli accelerate the central and peripheral motor processes that compose simple reaction time movements. The goal of the current study was to determine whether movements that are initiated to intense acoustic cues facilitate simple reaction times in (1) adults with chronic stroke as compared to age matched controls and (2) in older as compared to younger adults. EMG and force data were collected from three groups (stroke, older adults, and younger adults) during a ballistic wrist and finger extension task. Movements were made to the onset of 80 dB and 107 dB acoustic cues and simple reaction times were fractionated into premotor and motor components. The present findings offer two important contributions to the literature. First, increases in stimulus intensity led to faster motor times in the impaired limb of stroke subjects. Second, increased stimulus intensity led to faster premotor reaction times across all groups, although an age rather than a stroke-specific motor deficit was evidenced, with the younger control group displaying significantly faster premotor times. Findings are integrated with previous evidence concerning post stroke corticospinal tract integrity and are interpreted via mechanisms which address stroke and age-related changes in motoneurons and activity in motor units.

  8. Imaginary time approach for reaction rate of triple-alpha process

    NASA Astrophysics Data System (ADS)

    Yabana, Kazuhiro; Akahori, Takahiko; Funaki, Yasuro

    2014-09-01

    We propose a new theoretical approach for the radiative capture reaction rate, which we call the imaginary-time theory. In the theory, inverse temperature is identified with the temperature. Since reaction rates can be calculated without solving any scattering problem in the theory, it is ideally suited for the triple-alpha process in which scattering problem of three charged particles has caused difficulties. Using the imaginary-time theory, we obtain the triple-alpha reaction rate in the quantum three-body model treating alpha particles as structureless point particles. The calculated rate is almost identical to the standard NACRE rate. We have also found that the reaction mechanism of the triple-alpha process changes at exactly the same temperatures as those in empirical theories. We may show that it is possible to derive an analytical formula close to that of the NACRE rate, if we introduce some assumptions in the three-body model. We demonstrate that, if we introduce a coupled-channel expansion with a truncation, reaction rate is substantially overestimated. This finding may help to explain the very different reaction rates obtained so far using different theoretical approaches.

  9. The time dependent propensity function for acceleration of spatial stochastic simulation of reaction-diffusion systems

    NASA Astrophysics Data System (ADS)

    Fu, Jin; Wu, Sheng; Li, Hong; Petzold, Linda R.

    2014-10-01

    The inhomogeneous stochastic simulation algorithm (ISSA) is a fundamental method for spatial stochastic simulation. However, when diffusion events occur more frequently than reaction events, simulating the diffusion events by ISSA is quite costly. To reduce this cost, we propose to use the time dependent propensity function in each step. In this way we can avoid simulating individual diffusion events, and use the time interval between two adjacent reaction events as the simulation stepsize. We demonstrate that the new algorithm can achieve orders of magnitude efficiency gains over widely-used exact algorithms, scales well with increasing grid resolution, and maintains a high level of accuracy.

  10. The Time Dependent Propensity Function for Acceleration of Spatial Stochastic Simulation of Reaction-Diffusion Systems

    PubMed Central

    Wu, Sheng; Li, Hong; Petzold, Linda R.

    2015-01-01

    The inhomogeneous stochastic simulation algorithm (ISSA) is a fundamental method for spatial stochastic simulation. However, when diffusion events occur more frequently than reaction events, simulating the diffusion events by ISSA is quite costly. To reduce this cost, we propose to use the time dependent propensity function in each step. In this way we can avoid simulating individual diffusion events, and use the time interval between two adjacent reaction events as the simulation stepsize. We demonstrate that the new algorithm can achieve orders of magnitude efficiency gains over widely-used exact algorithms, scales well with increasing grid resolution, and maintains a high level of accuracy. PMID:26609185

  11. Effect of reaction time on the characteristics of catalytically grown boron nitride nanotubes

    SciTech Connect

    Mohamed, Norani Muti E-mail: pervaiz-pas@yahoo.com E-mail: zainabh@petronas.com.my; Ahmad, Pervaiz E-mail: pervaiz-pas@yahoo.com E-mail: zainabh@petronas.com.my; Saheed, Mohamed Shuaib Mohamed E-mail: pervaiz-pas@yahoo.com E-mail: zainabh@petronas.com.my; Burhanudin, Zainal Arif E-mail: pervaiz-pas@yahoo.com E-mail: zainabh@petronas.com.my

    2014-10-24

    The paper reports on the growth of boron nitride nanotube (BNNTs) on Si substrate by catalytic chemical vapor deposition technique and the effect of reaction time and temperature on the size and purity were investigated. Scanning electron microscopy image revealed the bamboo-like BNNTs of multiwalled type with interlayer spacing of 0.34 nm. EDX analysis described the presence of a small percentage of Mg in the sample, indicating the combination of base-tip growth model for the sample synthesized at 1200°C. The reaction time has an effect of extending the length of the BNNTs until the catalyst is oxidized or covered by growth precursor.

  12. Analysis of liver connexin expression using reverse transcription quantitative real-time polymerase chain reaction

    PubMed Central

    Maes, Michaël; Willebrords, Joost; Crespo Yanguas, Sara; Cogliati, Bruno; Vinken, Mathieu

    2016-01-01

    Summary Although connexin production is mainly regulated at the protein level, altered connexin gene expression has been identified as the underlying mechanism of several pathologies. When studying the latter, appropriate methods to quantify connexin mRNA levels are required. The present chapter describes a well-established reverse transcription quantitative real-time polymerase chain reaction procedure optimized for analysis of hepatic connexins. The method includes RNA extraction and subsequent quantification, generation of complementary DNA, quantitative real-time polymerase chain reaction and data analysis. PMID:27207283

  13. Reaction time of patients with Parkinson's disease, with reference to asymmetry of neurological signs.

    PubMed Central

    Yokochi, F; Nakamura, R; Narabayashi, H

    1985-01-01

    Electromyographic reaction times of the left and the right finger extensor muscles in extension movement of the wrist were examined in 42 patients with Parkinson's disease, and 20 normal subjects. Compared to the normal subjects and the patients with neurological signs confined to the right side, the patients with neurological signs on the left side or on both sides showed slowing of reaction times regardless of the side of responding hand. The patients with asymmetry of bilateral neurological signs showed slower RTs on the more affected side. PMID:4031916

  14. Analysis of Liver Connexin Expression Using Reverse Transcription Quantitative Real-Time Polymerase Chain Reaction.

    PubMed

    Maes, Michaël; Willebrords, Joost; Crespo Yanguas, Sara; Cogliati, Bruno; Vinken, Mathieu

    2016-01-01

    Although connexin production is mainly regulated at the protein level, altered connexin gene expression has been identified as the underlying mechanism of several pathologies. When studying the latter, appropriate methods to quantify connexin RNA levels are required. The present chapter describes a well-established reverse transcription quantitative real-time polymerase chain reaction procedure optimized for analysis of hepatic connexins. The method includes RNA extraction and subsequent quantification, generation of complementary DNA, quantitative real-time polymerase chain reaction, and data analysis. PMID:27207283

  15. Rotary acceleration of a subject inhibits choice reaction time to motion in peripheral vision

    NASA Technical Reports Server (NTRS)

    Borkenhagen, J. M.

    1974-01-01

    Twelve pilots were tested in a rotation device with visual simulation, alone and in combination with rotary stimulation, in experiments with variable levels of acceleration and variable viewing angles, in a study of the effect of S's rotary acceleration on the choice reaction time for an accelerating target in peripheral vision. The pilots responded to the direction of the visual motion by moving a hand controller to the right or left. Visual-plus-rotary stimulation required a longer choice reaction time, which was inversely related to the level of acceleration and directly proportional to the viewing angle.

  16. Stochastic binary modeling of cells in continuous time as an alternative to biochemical reaction equations.

    PubMed

    Teraguchi, Shunsuke; Kumagai, Yutaro; Vandenbon, Alexis; Akira, Shizuo; Standley, Daron M

    2011-12-01

    We have developed a coarse-grained formulation for modeling the dynamic behavior of cells quantitatively, based on stochasticity and heterogeneity, rather than on biochemical reactions. We treat each reaction as a continuous-time stochastic process, while reducing each biochemical quantity to a binary value at the level of individual cells. The system can be analytically represented by a finite set of ordinary linear differential equations, which provides a continuous time course prediction of each molecular state. Here we introduce our formalism and demonstrate it with several examples.

  17. The Influence of Ball Velocity and Court Illumination on Reaction Time for Tennis Volley

    PubMed Central

    Tu, Jui-hung; Lin, Yaw-feng; Chin, Shu-chen

    2010-01-01

    The he purpose of this study is to examine the effects of ball velocity, court illumination, and volley type on the reaction time (RT) of a tennis athlete for a volley stroke. Eights cases with two different ball velocities (high and low), two volley types (forehand and backhand ) and two court illumination levels (dark and bright) were studied. The 30 participating subjects consisted of 18 male and 12 female college tennis athletes (age: 24 ± 3.2 yr), with a United States Tennis Association (USTA) ranking above 2.5. In order to ensure the validity of real-world correlations, the experiments were designed to simulate real competition situations. Reaction times were measured for volley strokes in response to different approaching ball velocities (high: 25.05 ± 0.37 m/s and low: 17.56 ± 0.92 m·s-1) for several volley types (forehand and backhand) and court illumination levels (55649 ± 4292 lux and 363.24 ± 6.53 lux on the court). During the tests, the signals from an electromyogram sensor and a 3-axis accelerometer (± 50 g) were recorded using an NI DAQ card (NI PXI-6251) and then analyzed to determine reaction time (RT), premotor reaction time (PRT), and motor reaction time (MRT) through the LabVIEW system. Subsequent 3-way ANOVA analysis indicated no RT, PRT, or MRT interaction between ball velocity, volley type and illumination. The ball velocity and illumination parameters did affect RT and PRT values significantly with p < 0.05, no significant variation in MRT was observed across any implemented experimental conditions. All experimental results indicate that ball velocity and illumination levels strongly affect the value of PRT, but have no significant effect on the value of MRT, the changes in RT were dominated by PRT. Key points RT can generally be divided into two components with the help of the electromyogram (EMG) signal - the premotor reaction time (PRT) and the motor reaction time (MRT). The purpose of this study is to examine the effects of ball

  18. Stutterers' vocal reaction times to unilaterally presented high and low frequency verbs.

    PubMed

    Rami, M K; Shine, R E; Rastatter, M P

    2000-08-01

    The current study investigated vocal reaction times of 11 stuttering participants to verbs with high and low frequencies of occurrence when these verbs were unilaterally visually presented. No significant main effects or interactions between stimuli and visual-half field were found. Reaction times were 16 msec. faster after right visual field presentations and the Pearson correlation coefficient between visual fields .71 (p=.02). These results were interpreted as suggesting that the left hemisphere was dominant for processing the current lexical items, findings which parallel those for normal speakers.

  19. The relationship between naming reaction time and functional MRI parameters in Broca's area.

    PubMed

    Cummine, Jacqueline; Borowsky, Ron; Vakorin, Vasily; Bird, Jeff; Sarty, Gordon

    2008-07-01

    We examined the correlation between behavioural reaction time and functional imaging parameters of the blood oxygenated level dependent (BOLD) response in Broca's Area during a word identification task, and whether the correlation [Magnetic Resonance Imaging 22 (2004) 451-455] varies as a function of four stimulus types: regular words (REGs) (e.g., hint), irregular words (IRRs) (e.g., pint), nonwords (NWs) (e.g., bint), and pseudohomophones (PHs) (e.g., pynt). Participants named letter strings aloud during a functional magnetic resonance imaging study. Naming reaction times were recorded during regular gaps in image acquisition, and BOLD parameters were extracted via a Tikhonov regularized BOLD analysis technique. The results revealed that only PH reaction times were correlated with BOLD width, providing evidence that Broca's area supports phonetic decoding accompanied with phonological lexical access. In addition, we advanced the development of equation-based models of cognitive behaviour and neurophysiology, whereby we showed that the relationship of mathematical independence that exists for predicting REG accuracy, given IRR and NW or PH naming accuracy, was present for naming reaction time, BOLD width, BOLD time to peak, and BOLD intensity. Therefore, we provide converging behavioural and neuroanatomical evidence for a mathematically independent relationship between sight vocabulary and phonetic decoding systems, consistent with a dual-route model of reading.

  20. An analysis on driver drowsiness based on reaction time and EEG band power.

    PubMed

    Ruyi Foong; Kai Keng Ang; Chai Quek; Cuntai Guan; Aung Aung Phyo Wai

    2015-08-01

    Falling asleep during driving is a serious problem that has resulted in fatal accidents worldwide. Thus, there is a need to detect driver drowsiness to counter it. This study analyzes the changes in the electroencephalography (EEG) collected from 4 subjects driving under monotonous road conditions using a driving simulator. The drowsiness level of the subjects is inferred from the time taken to react to events. The results from the analysis of the reaction time shows that drowsiness occurs in cycles, which correspond to short sleep cycles known as `microsleeps'. The results from a time-frequency analysis of the four frequency bands' power reveals differences between trials with fast and slow reaction times; greater beta band power is present in all subjects, greater alpha power in 2 subjects, greater theta power in 2 subjects, and greater delta power in 3 subjects, for fast reaction trials. Overall, this study shows that reaction time can be used to infer the drowsiness, and subject-specific changes in the EEG band power may be used to infer drowsiness. Thus the study shows a promising prospect of developing Brain-Computer Interface to detect driver drowsiness. PMID:26738144

  1. Correlative Time-Resolved Fluorescence Microscopy To Assess Antibiotic Diffusion-Reaction in Biofilms

    PubMed Central

    Daddi Oubekka, S.; Briandet, R.; Fontaine-Aupart, M.-P.

    2012-01-01

    The failure of antibiotics to inactivate in vivo pathogens organized in biofilms has been shown to trigger chronic infections. In addition to mechanisms involving specific genetic or physiological cell properties, antibiotic sorption and/or reaction with biofilm components may lessen the antibiotic bioavailability and consequently decrease their efficiency. To assess locally and accurately the antibiotic diffusion-reaction, we used for the first time a set of advanced fluorescence microscopic tools (fluorescence recovery after photobleaching, fluorescence correlation spectroscopy, and fluorescence lifetime imaging) that offer a spatiotemporal resolution not available with the commonly used time-lapse confocal imaging method. This set of techniques was used to characterize the dynamics of fluorescently labeled vancomycin in biofilms formed by two Staphylococcus aureus human isolates. We demonstrate that, at therapeutic concentrations of vancomycin, the biofilm matrix was not an obstacle to the diffusion-reaction of the antibiotic that can reach all cells through the biostructure. PMID:22450986

  2. Motor cortex involvement during choice reaction time: a transcranial magnetic stimulation study in man.

    PubMed

    Romaiguère, P; Possamaï, C A; Hasbroucq, T

    1997-05-01

    It has been shown that transcranial magnetic stimulation can delay simple reaction time; this happens when the stimulation is delivered during the reaction time and over the cortical area which commands the prime mover of the required response. Although it is agreed that magnetic stimulation could be a useful tool for studying information processing in man, we argue that, because of the use of simple reaction time, the results reported so far are difficult to interpret within this theoretical framework. In the present paper, three experiments are reported. Six subjects participated in experiment 1 in which magnetic stimulation was delivered, at different times, during choice reaction time. The effects of the magnetic stimulation of the cortical area involved in the response (induced current passing forward over the motor representation of the responding hand), were compared to the effects of an electrical stimulation of the median nerve (H-reflex). In a first control experiment (experiment 2a; 5 subjects), the coil was placed over the ipsilateral motor cortex (induced current passing backward over the motor representation of the non-responding hand) thus minimizing the probability to excite the same neural nets as in the first experiment. In a second control experiment (experiment 2b; 4 subjects), the coil was placed a few centimeters away from the subject's scalp thus ensuring no stimulation of any neural nets. The results show that: (1) the noise and the smarting of the skin associated with the coil discharge produce an intersensory facilitation thereby shortening reaction time (experiment 2a), (2) actually, the noise produced by the stimulation is sufficient to produce such a facilitatory effect (experiment 2b), (3) a stimulation over the area at the origin of the motor command causes a reaction time delay which counteracts this intersensory facilitation effect (experiment 1), (4) in this latter case, the closer the stimulation to the actual overt response, the

  3. The cortisol awakening response is associated with performance of a serial sequence reaction time task.

    PubMed

    Hodyl, Nicolette A; Schneider, Luke; Vallence, Ann-Maree; Clow, Angela; Ridding, Michael C; Pitcher, Julia B

    2016-02-01

    There is emerging evidence of a relationship between the cortisol awakening response (CAR) and the neural mechanisms underlying learning and memory. The aim of this study was to determine whether the CAR is associated with acquisition, retention and overnight consolidation or improvement of a serial sequence reaction time task. Salivary samples were collected at 0, 15, 30 and 45 min after awakening in 39 healthy adults on 2 consecutive days. The serial sequence reaction time task was repeated each afternoon. Participants completed the perceived stress scale and provided salivary samples prior to testing for cortisol assessment. While the magnitude of the CAR (Z score) was not associated with either baseline performance or the timed improvement during task acquisition of the serial sequence task, a positive correlation was observed with reaction times during the stable performance phase on day 1 (r=0.373, p=0.019). Residuals derived from the relationship between baseline and stable phase reaction times on day 1 were used as a surrogate for the degree of learning: these residuals were also correlated with the CAR mean increase on day 1 (r=0.357, p=0.048). Task performance on day 2 was not associated with the CAR obtained on this same day. No association was observed between the perceived stress score, cortisol at testing or task performance. These data indicate that a smaller CAR in healthy adults is associated with a greater degree of learning and faster performance of a serial sequence reaction time task. These results support recognition of the CAR as an important factor contributing to cognitive performance throughout the day.

  4. A parametric duration model of the reaction times of drivers distracted by mobile phone conversations.

    PubMed

    Haque, Md Mazharul; Washington, Simon

    2014-01-01

    The use of mobile phones while driving is more prevalent among young drivers-a less experienced cohort with elevated crash risk. The objective of this study was to examine and better understand the reaction times of young drivers to a traffic event originating in their peripheral vision whilst engaged in a mobile phone conversation. The CARRS-Q advanced driving simulator was used to test a sample of young drivers on various simulated driving tasks, including an event that originated within the driver's peripheral vision, whereby a pedestrian enters a zebra crossing from a sidewalk. Thirty-two licensed drivers drove the simulator in three phone conditions: baseline (no phone conversation), hands-free and handheld. In addition to driving the simulator each participant completed questionnaires related to driver demographics, driving history, usage of mobile phones while driving, and general mobile phone usage history. The participants were 21-26 years old and split evenly by gender. Drivers' reaction times to a pedestrian in the zebra crossing were modelled using a parametric accelerated failure time (AFT) duration model with a Weibull distribution. Also tested where two different model specifications to account for the structured heterogeneity arising from the repeated measures experimental design. The Weibull AFT model with gamma heterogeneity was found to be the best fitting model and identified four significant variables influencing the reaction times, including phone condition, driver's age, license type (provisional license holder or not), and self-reported frequency of usage of handheld phones while driving. The reaction times of drivers were more than 40% longer in the distracted condition compared to baseline (not distracted). Moreover, the impairment of reaction times due to mobile phone conversations was almost double for provisional compared to open license holders. A reduction in the ability to detect traffic events in the periphery whilst distracted

  5. Displaying Special Characters and Symbols in Computer-Controlled Reaction Time Experiments.

    ERIC Educational Resources Information Center

    Friel, Brian M.; Kennison, Shelia M.

    A procedure for using MEL2 (Version 2.0 of Microcomputer Experimental Laboratory) and FontWINDOW to present special characters and symbols in computer-controlled reaction time experiments is described. The procedure permits more convenience and flexibility than in tachistocopic and projection techniques. FontWINDOW allows researchers to design…

  6. The Effect of Feedback Schedule Manipulation on Speech Priming Patterns and Reaction Time

    ERIC Educational Resources Information Center

    Slocomb, Dana; Spencer, Kristie A.

    2009-01-01

    Speech priming tasks are frequently used to delineate stages in the speech process such as lexical retrieval and motor programming. These tasks, often measured in reaction time (RT), require fast and accurate responses, reflecting maximized participant performance, to result in robust priming effects. Encouraging speed and accuracy in responding…

  7. The Effect of Intervention on Accuracy of Students' Responses and Reaction Times to Geometry Problems

    ERIC Educational Resources Information Center

    Babai, Reuven; Zilber, Hanna; Stavy, Ruth; Tirosh, Dina

    2010-01-01

    This study investigates the effect on student performance in drawing their attention to relevant task variables, focusing on accuracy of responses and reaction times. We chose this methodology in order to better understand how such interventions affect the reasoning process. The study employs a geometry task in which the irrelevant salient…

  8. Relating Derived Relations as a Model of Analogical Reasoning: Reaction Times and Event-Related Potentials

    ERIC Educational Resources Information Center

    Barnes-Holmes, Dermot; Regan, Donal; Barnes-Holmes, Yvonne; Commins, Sean; Walsh, Derek; Stewart, Ian; Smeets, Paul M.; Whelan, Robert; Dymond, Simon

    2005-01-01

    The current study aimed to test a Relational Frame Theory (RFT) model of analogical reasoning based on the relating of derived same and derived difference relations. Experiment 1 recorded reaction time measures of similar-similar (e.g., "apple is to orange as dog is to cat") versus different-different (e.g., "he is to his brother as chalk is to…

  9. Category Induction via Distributional Analysis: Evidence from a Serial Reaction Time Task

    ERIC Educational Resources Information Center

    Hunt, Ruskin H.; Aslin, Richard N.

    2010-01-01

    Category formation lies at the heart of a number of higher-order behaviors, including language. We assessed the ability of human adults to learn, from distributional information alone, categories embedded in a sequence of input stimuli using a serial reaction time task. Artificial grammars generated corpora of input strings containing a…

  10. A new Sumudu transform iterative method for time-fractional Cauchy reaction-diffusion equation.

    PubMed

    Wang, Kangle; Liu, Sanyang

    2016-01-01

    In this paper, a new Sumudu transform iterative method is established and successfully applied to find the approximate analytical solutions for time-fractional Cauchy reaction-diffusion equations. The approach is easy to implement and understand. The numerical results show that the proposed method is very simple and efficient. PMID:27386314

  11. The Persistence of "Solid" and "Liquid" Naive Conceptions: A Reaction Time Study

    ERIC Educational Resources Information Center

    Babai, Reuven; Amsterdamer, Anat

    2008-01-01

    The study explores whether the naive concepts of "solid" and "liquid" persist in adolescence. Accuracy of responses and reaction times where measured while 41 ninth graders classified different solids (rigid, non-rigid and powders) and different liquids (runny, dense) into solid or liquid. The results show that these naive conceptions affect…

  12. Age-Related Differences in Reaction Time Task Performance in Young Children

    ERIC Educational Resources Information Center

    Kiselev, Sergey; Espy, Kimberlay Andrews; Sheffield, Tiffany

    2009-01-01

    Performance of reaction time (RT) tasks was investigated in young children and adults to test the hypothesis that age-related differences in processing speed supersede a "global" mechanism and are a function of specific differences in task demands and processing requirements. The sample consisted of 54 4-year-olds, 53 5-year-olds, 59 6-year-olds,…

  13. Cognitive performance and BMI in childhood: Shared genetic influences between reaction time but not response inhibition

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The aim of this work is to understand whether shared genetic influences can explain the associationbetween obesity and cognitive performance, including slower and more variable reaction times(RTs) and worse response inhibition. RT on a four-choice RT task and the go/no-go task, and commission errors...

  14. Naturally Biased? In Search for Reaction Time Evidence for a Natural Number Bias in Adults

    ERIC Educational Resources Information Center

    Vamvakoussi, Xenia; Van Dooren, Wim; Verschaffel, Lieven

    2012-01-01

    A major source of errors in rational number tasks is the inappropriate application of natural number rules. We hypothesized that this is an instance of intuitive reasoning and thus can persist in adults, even when they respond correctly. This was tested by means of a reaction time method, relying on a dual process perspective that differentiates…

  15. Processing of Emotion Words by Patients with Autism Spectrum Disorders: Evidence from Reaction Times and EEG

    ERIC Educational Resources Information Center

    Lartseva, Alina; Dijkstra, Ton; Kan, Cornelis C.; Buitelaar, Jan K.

    2014-01-01

    This study investigated processing of emotion words in autism spectrum disorders (ASD) using reaction times and event-related potentials (ERP). Adults with (n = 21) and without (n = 20) ASD performed a lexical decision task on emotion and neutral words while their brain activity was recorded. Both groups showed faster responses to emotion words…

  16. Sentence Processing in High Proficient Kannada--English Bilinguals: A Reaction Time Study

    ERIC Educational Resources Information Center

    Ravi, Sunil Kumar; Chengappa, Shyamala K.

    2015-01-01

    The present study aimed at exploring the semantic and syntactic processing differences between native and second languages in 20 early high proficient Kannada--English bilingual adults through accuracy and reaction time (RT) measurements. Subjects participated in a semantic judgement task (using 50 semantically correct and 50 semantically…

  17. Eye Colour and Reaction Time: An Opportunity for Critical Statistical Reasoning

    ERIC Educational Resources Information Center

    Watson, Jane

    2008-01-01

    This author was surprised to read a short article in "The Mercury" newspaper in Hobart about blue-eyed people being more intelligent and brown-eyed people having faster reaction times. Such an article invites immediate scepticism from the statistically literate. The lack of data in the article should lead the interested reader to a search for…

  18. More Symmetrical Children Have Faster and More Consistent Choice Reaction Times

    ERIC Educational Resources Information Center

    Hope, David; Bates, Timothy C.; Dykiert, Dominika; Der, Geoff; Deary, Ian J.

    2015-01-01

    Greater cognitive ability in childhood is associated with increased longevity, and speedier reaction time (RT) might account for much of this linkage. Greater bodily symmetry is linked to both higher cognitive test scores and faster RTs. It is possible, then, that differences in bodily system integrity indexed by symmetry may underlie the…

  19. Peripheral Nerve Conduction Velocity, Reaction Time, and Intelligence: An Attempt to Replicate Vernon and Mori.

    ERIC Educational Resources Information Center

    Wickett, John C.; Vernon, Philip A.

    1994-01-01

    In a study involving 38 adult females, nerve conduction velocity (NCV) did not correlate with intelligence or reaction time. A reanalysis of the Vernon and Mori data showed a possible sex difference in relation to NCV and intelligence, with the correlation between these variables much smaller in females than males. (SLD)

  20. Design and optimization of molecular beacon real-time polymerase chain reaction assays.

    PubMed

    Vet, Jacqueline A M; Marras, Salvatore A E

    2005-01-01

    During the last few years, several innovative technologies have become available for performing sensitive and accurate genetic analyses. These techniques use fluorescent detection strategies in combination with nucleic acid amplification protocols. Most commonly used is the real-time polymerase chain reaction (PCR). To achieve the maximum potential of a real-time PCR assay, several parameters must be evaluated and optimized independently. This chapter describes the different steps necessary for establishing a molecular beacon real-time PCR assay: (1) target design, (2) primer design, (3) optimization of the amplification reaction conditions using SYBR Green, (4) molecular beacon design, and (5) molecular beacon synthesis and characterization. The last section provides an example of a multiplex quantitative real-time PCR.

  1. Contaminant transport in soil with depth-dependent reaction coefficients and time-dependent boundary conditions.

    PubMed

    Gao, Guangyao; Fu, Bojie; Zhan, Hongbin; Ma, Ying

    2013-05-01

    Predicting the fate and movement of contaminant in soils and groundwater is essential to assess and reduce the risk of soil contamination and groundwater pollution. Reaction processes of contaminant often decreased monotonously with depth. Time-dependent input sources usually occurred at the inlet of natural or human-made system such as radioactive waste disposal site. This study presented a one-dimensional convection-dispersion equation (CDE) for contaminant transport in soils with depth-dependent reaction coefficients and time-dependent inlet boundary conditions, and derived its analytical solution. The adsorption coefficient and degradation rate were represented as sigmoidal functions of soil depth. Solute breakthrough curves (BTCs) and concentration profiles obtained from CDE with depth-dependent and constant reaction coefficients were compared, and a constant effective reaction coefficient, which was calculated by arithmetically averaging the depth-dependent reaction coefficient, was proposed to reflect the lumped depth-dependent reaction effect. With the effective adsorption coefficient and degradation rate, CDE could produce similar BTCs and concentration profiles as those from CDE with depth-dependent reactions in soils with moderate chemical heterogeneity. In contrast, the predicted concentrations of CDE with fitted reaction coefficients at a certain depth departed significantly from those of CDE with depth-dependent reactions. Parametric analysis was performed to illustrate the effects of sinusoidally and exponentially decaying input functions on solute BTCs. The BTCs and concentration profiles obtained from the solutions for finite and semi-infinite domain were compared to investigate the effects of effluent boundary condition. The finite solution produced higher concentrations at the increasing limb of the BTCs and possessed a higher peak concentration than the semi-infinite solution which had a slightly long tail. Furthermore, the finite solution gave

  2. Contaminant transport in soil with depth-dependent reaction coefficients and time-dependent boundary conditions.

    PubMed

    Gao, Guangyao; Fu, Bojie; Zhan, Hongbin; Ma, Ying

    2013-05-01

    Predicting the fate and movement of contaminant in soils and groundwater is essential to assess and reduce the risk of soil contamination and groundwater pollution. Reaction processes of contaminant often decreased monotonously with depth. Time-dependent input sources usually occurred at the inlet of natural or human-made system such as radioactive waste disposal site. This study presented a one-dimensional convection-dispersion equation (CDE) for contaminant transport in soils with depth-dependent reaction coefficients and time-dependent inlet boundary conditions, and derived its analytical solution. The adsorption coefficient and degradation rate were represented as sigmoidal functions of soil depth. Solute breakthrough curves (BTCs) and concentration profiles obtained from CDE with depth-dependent and constant reaction coefficients were compared, and a constant effective reaction coefficient, which was calculated by arithmetically averaging the depth-dependent reaction coefficient, was proposed to reflect the lumped depth-dependent reaction effect. With the effective adsorption coefficient and degradation rate, CDE could produce similar BTCs and concentration profiles as those from CDE with depth-dependent reactions in soils with moderate chemical heterogeneity. In contrast, the predicted concentrations of CDE with fitted reaction coefficients at a certain depth departed significantly from those of CDE with depth-dependent reactions. Parametric analysis was performed to illustrate the effects of sinusoidally and exponentially decaying input functions on solute BTCs. The BTCs and concentration profiles obtained from the solutions for finite and semi-infinite domain were compared to investigate the effects of effluent boundary condition. The finite solution produced higher concentrations at the increasing limb of the BTCs and possessed a higher peak concentration than the semi-infinite solution which had a slightly long tail. Furthermore, the finite solution gave

  3. The sound of a mobile phone ringing affects the complex reaction time of its owner

    PubMed Central

    Zajdel, Justyna; Zwolińska, Anna; Śmigielski, Janusz; Beling, Piotr; Cegliński, Tomasz; Nowak, Dariusz

    2012-01-01

    Introduction Mobile phone conversation decreases the ability to concentrate and impairs the attention necessary to perform complex activities, such as driving a car. Does the ringing sound of a mobile phone affect the driver's ability to perform complex sensory-motor activities? We compared a subject's reaction time while performing a test either with a mobile phone ringing or without. Material and methods The examination was performed on a PC-based reaction time self-constructed system Reactor. The study group consisted of 42 healthy students. The protocol included instruction, control without phone and a proper session with subject's mobile phone ringing. The terms of the study were standardised. Results There were significant differences (p < 0.001) in reaction time in control (597 ms), mobile (633 ms) and instruction session (673 ms). The differences in female subpopulation were also significant (p < 0.01). Women revealed the longest reaction time in instruction session (707 ms), were significantly quicker in mobile (657 ms, p < 0.01) and in control session (612 ms, p < 0.001). In men, the significant difference was recorded only between instruction (622 ms) and control session (573 ms, p < 0.01). The other differences were not significant (p > 0.08). Men proofed to complete significantly quicker than women in instruction (p < 0.01) and in mobile session (p < 0.05). Differences amongst the genders in control session was not significant (p > 0.05). Conclusions The results obtained proofed the ringing of a phone exerts a significant influence on complex reaction time and quality of performed task. PMID:23185201

  4. Time capsule: an autonomous sensor and recorder based on diffusion-reaction.

    PubMed

    Gerber, Lukas C; Rosenfeld, Liat; Chen, Yunhan; Tang, Sindy K Y

    2014-11-21

    We describe the use of chemical diffusion and reaction to record temporally varying chemical information as spatial patterns without the need for external power. Diffusion of chemicals acts as a clock, while reactions forming immobile products possessing defined optical properties perform sensing and recording functions simultaneously. The spatial location of the products reflects the history of exposure to the detected substances of interest. We refer to our device as a time capsule and show an initial proof of principle in the autonomous detection of lead ions in water.

  5. Finite element procedures for time-dependent convection-diffusion-reaction systems

    NASA Technical Reports Server (NTRS)

    Tezduyar, T. E.; Park, Y. J.; Deans, H. A.

    1988-01-01

    New finite element procedures based on the streamline-upwind/Petrov-Galerkin formulations are developed for time-dependent convection-diffusion-reaction equations. These procedures minimize spurious oscillations for convection-dominated and reaction-dominated problems. The results obtained for representative numerical examples are accurate with minimal oscillations. As a special application problem, the single-well chemical tracer test (a procedure for measuring oil remaining in a depleted field) is simulated numerically. The results show the importance of temperature effects on the interpreted value of residual oil saturation from such tests.

  6. Application of real-time polymerase chain reaction in the clinical genetic practice.

    PubMed

    Nagy, Bálint

    2013-03-01

    The development of polymerase chain reaction revolutionized the molecular genetics and diagnostics. Technical improvements helped to make more specific and sensitive target determinations. Introduction of real-time polymerase chain reaction makes possible several applications in clinical genetics like detection of gene mutations, single nucleotide polymorphisms, deletions, measurement of gene expressions, micro ribonucleic acids, free nucleic acids and microbial genomes. Here I discuss a few examples for specific applications in prenatal clinical genetic practice. These are the detection of microbial genomes, deletions, trisomies, mutations, single nucleotide polymorphisms and free nucleic acids. PMID:27625833

  7. Application of real-time polymerase chain reaction in the clinical genetic practice

    PubMed Central

    Nagy, Bálint

    2013-01-01

    The development of polymerase chain reaction revolutionized the molecular genetics and diagnostics. Technical improvements helped to make more specific and sensitive target determinations. Introduction of real-time polymerase chain reaction makes possible several applications in clinical genetics like detection of gene mutations, single nucleotide polymorphisms, deletions, measurement of gene expressions, micro ribonucleic acids, free nucleic acids and microbial genomes. Here I discuss a few examples for specific applications in prenatal clinical genetic practice. These are the detection of microbial genomes, deletions, trisomies, mutations, single nucleotide polymorphisms and free nucleic acids.

  8. Defining Lagrangian coherent structures for reactions in time-aperiodic flows

    NASA Astrophysics Data System (ADS)

    Mitchell, Kevin; Mahoney, John

    2014-11-01

    Recent theoretical and experimental investigations have highlighted the role of invariant manifolds, termed burning invariant manifolds (BIMs), as one-way barriers to reaction fronts propagating through a flowing medium. Originally, BIM theory was restricted to time-independent or time-periodic flows. The present work extends these ideas to flows with a general time-dependence, thereby constructing coherent structures that organize and constrain the propagation of reaction fronts through general flows. This permits a much broader and physically realistic class of problems to be addressed. Our approach follows the recent work of Farazmand, Blazevski, and Haller [Physica D 44, 278 (2014)], in which Lagrangian coherent structures (LCSs), relevant to purely advective transport, are characterized as curves of minimal Lagrangian shear. Supported by the US National Science Foundation under Grant CMMI-1201236.

  9. Chemical dynamics in the gas phase: Time-dependent quantum mechanics of chemical reactions

    SciTech Connect

    Gray, S.K.

    1993-12-01

    A major goal of this research is to obtain an understanding of the molecular reaction dynamics of three and four atom chemical reactions using numerically accurate quantum dynamics. This work involves: (i) the development and/or improvement of accurate quantum mechanical methods for the calculation and analysis of the properties of chemical reactions (e.g., rate constants and product distributions), and (ii) the determination of accurate dynamical results for selected chemical systems, which allow one to compare directly with experiment, determine the reliability of the underlying potential energy surfaces, and test the validity of approximate theories. This research emphasizes the use of recently developed time-dependent quantum mechanical methods, i.e. wave packet methods.

  10. Real-time observations of lithium battery reactions-operando neutron diffraction analysis during practical operation.

    PubMed

    Taminato, Sou; Yonemura, Masao; Shiotani, Shinya; Kamiyama, Takashi; Torii, Shuki; Nagao, Miki; Ishikawa, Yoshihisa; Mori, Kazuhiro; Fukunaga, Toshiharu; Onodera, Yohei; Naka, Takahiro; Morishima, Makoto; Ukyo, Yoshio; Adipranoto, Dyah Sulistyanintyas; Arai, Hajime; Uchimoto, Yoshiharu; Ogumi, Zempachi; Suzuki, Kota; Hirayama, Masaaki; Kanno, Ryoji

    2016-01-01

    Among the energy storage devices for applications in electric vehicles and stationary uses, lithium batteries typically deliver high performance. However, there is still a missing link between the engineering developments for large-scale batteries and the fundamental science of each battery component. Elucidating reaction mechanisms under practical operation is crucial for future battery technology. Here, we report an operando diffraction technique that uses high-intensity neutrons to detect reactions in non-equilibrium states driven by high-current operation in commercial 18650 cells. The experimental system comprising a time-of-flight diffractometer with automated Rietveld analysis was developed to collect and analyse diffraction data produced by sequential charge and discharge processes. Furthermore, observations under high current drain revealed inhomogeneous reactions, a structural relaxation after discharge, and a shift in the lithium concentration ranges with cycling in the electrode matrix. The technique provides valuable information required for the development of advanced batteries. PMID:27357605

  11. Time-Resolved FTIR Study on the Reaction of CHCl2 with NO2

    NASA Astrophysics Data System (ADS)

    Liu, Kun-hui; Yang, Chun-fan; Wang, Huan; Wu, Wei-qiang; Su, Hong-mei

    2009-04-01

    The environmentally important free radical reaction of chlorinated methyl CHCl2 with NO2 was investigated by step-scan time-resolved FTIR (TR-FTIR) emission spectroscopy. Vibrationally excited products of CHClO, NO, CO, and HCl are observed in the high-resolution IR emission spectra and three possible reaction channels are therefore elucidated. In particular, the product CO is newly detected and the product HCl is identified explicitly as a yield from the CHCl2+NO2 reaction, taking advantage of the sensitive detection of HCl and CO with TR-FTIR. These results are of particular interests to understand the related realistic chemical processes including atmospheric photochemistry, biofuel combustion, waste destruction, and smoking fire.

  12. Real-time observations of lithium battery reactions-operando neutron diffraction analysis during practical operation.

    PubMed

    Taminato, Sou; Yonemura, Masao; Shiotani, Shinya; Kamiyama, Takashi; Torii, Shuki; Nagao, Miki; Ishikawa, Yoshihisa; Mori, Kazuhiro; Fukunaga, Toshiharu; Onodera, Yohei; Naka, Takahiro; Morishima, Makoto; Ukyo, Yoshio; Adipranoto, Dyah Sulistyanintyas; Arai, Hajime; Uchimoto, Yoshiharu; Ogumi, Zempachi; Suzuki, Kota; Hirayama, Masaaki; Kanno, Ryoji

    2016-06-30

    Among the energy storage devices for applications in electric vehicles and stationary uses, lithium batteries typically deliver high performance. However, there is still a missing link between the engineering developments for large-scale batteries and the fundamental science of each battery component. Elucidating reaction mechanisms under practical operation is crucial for future battery technology. Here, we report an operando diffraction technique that uses high-intensity neutrons to detect reactions in non-equilibrium states driven by high-current operation in commercial 18650 cells. The experimental system comprising a time-of-flight diffractometer with automated Rietveld analysis was developed to collect and analyse diffraction data produced by sequential charge and discharge processes. Furthermore, observations under high current drain revealed inhomogeneous reactions, a structural relaxation after discharge, and a shift in the lithium concentration ranges with cycling in the electrode matrix. The technique provides valuable information required for the development of advanced batteries.

  13. Effect of hydrothermal reaction time and alkaline conditions on the electrochemical properties of reduced graphene oxide

    NASA Astrophysics Data System (ADS)

    Vermisoglou, E. C.; Giannakopoulou, T.; Romanos, G.; Giannouri, M.; Boukos, N.; Lei, C.; Lekakou, C.; Trapalis, C.

    2015-12-01

    Reduced graphene oxide sheets (rGO) were prepared by hydrothermal treatment of aqueous dispersions of graphite oxide (GtO) applied for short (4 h) and prolonged reaction times (19-24 h). The effect of process duration as well as the alkaline conditions (pH ∼10) by addition of K2CO3 on the quality characteristics of the produced rGO materials was investigated. Both reduction and exfoliation occurred during this process as it was evidenced by FTIR and XRD data. SEM, TEM and HRTEM microscopy displayed highly exfoliated rGO materials. XPS verified that the re-establishment of the conjugated graphene network is more extensive for prolonged times of hydrothermal processing in accordance to Raman spectroscopy measurements. The sample produced under alkaline conditions bore fewer defects and almost 5 times higher BET surface area (∼181 m2/g) than the sample with no pH adjustment (∼34 m2/g) for the same hydrothermal reaction time (19 h), attributed to the developed microporosity. The specific capacitance of this material estimated by electrochemical impedance using three-electrode cell and KCl aqueous solution as an electrolyte was ∼400-500 F/g. When EDLC capacitors were fabricated from rGO materials the electrochemical testing in organic electrolyte i.e. TEABF4 in PC, revealed that the shortest hydrothermal reaction time (4 h) was more efficient resulting in capacitance around 60 F/g.

  14. Analysis of Thermal and Reaction Times for Hydrogen Reduction of Lunar Regolith

    NASA Technical Reports Server (NTRS)

    Hegde, U.; Balasubramaniam, R.; Gokoglu, S.

    2009-01-01

    System analysis of oxygen production by hydrogen reduction of lunar regolith has shown the importance of the relative time scales for regolith heating and chemical reaction to overall performance. These values determine the sizing and power requirements of the system and also impact the number and operational phasing of reaction chambers. In this paper, a Nusselt number correlation analysis is performed to determine the heat transfer rates and regolith heat up times in a fluidized bed reactor heated by a central heating element (e.g., a resistively heated rod, or a solar concentrator heat pipe). A coupled chemical and transport model has also been developed for the chemical reduction of regolith by a continuous flow of hydrogen. The regolith conversion occurs on the surfaces of and within the regolith particles. Several important quantities are identified as a result of the above analyses. Reactor scale parameters include the void fraction (i.e., the fraction of the reactor volume not occupied by the regolith particles) and the residence time of hydrogen in the reactor. Particle scale quantities include the particle Reynolds number, the Archimedes number, and the time needed for hydrogen to diffuse into the pores of the regolith particles. The analysis is used to determine the heat up and reaction times and its application to NASA s oxygen production system modeling tool is noted.

  15. Analysis of Thermal and Reaction Times for Hydrogen Reduction of Lunar Regolith

    NASA Technical Reports Server (NTRS)

    Hegde, U.; Balasubramaniam, R.; Gokoglu, S.

    2008-01-01

    System analysis of oxygen production by hydrogen reduction of lunar regolith has shown the importance of the relative time scales for regolith heating and chemical reaction to overall performance. These values determine the sizing and power requirements of the system and also impact the number and operational phasing of reaction chambers. In this paper, a Nusselt number correlation analysis is performed to determine the heat transfer rates and regolith heat up times in a fluidized bed reactor heated by a central heating element (e.g., a resistively heated rod, or a solar concentrator heat pipe). A coupled chemical and transport model has also been developed for the chemical reduction of regolith by a continuous flow of hydrogen. The regolith conversion occurs on the surfaces of and within the regolith particles. Several important quantities are identified as a result of the above analyses. Reactor scale parameters include the void fraction (i.e., the fraction of the reactor volume not occupied by the regolith particles) and the residence time of hydrogen in the reactor. Particle scale quantities include the particle Reynolds number, the Archimedes number, and the time needed for hydrogen to diffuse into the pores of the regolith particles. The analysis is used to determine the heat up and reaction times and its application to NASA s oxygen production system modeling tool is noted.

  16. Evaluation of direct analysis in real time mass spectrometry for onsite monitoring of batch slurry reactions.

    PubMed

    Cho, David S; Gibson, Stephen C; Bhandari, Deepak; McNally, Mary Ellen; Hoffman, Ron M; Cook, Kelsey D; Song, Liguo

    2011-12-15

    Batch slurry reactions are widely used in the industrial manufacturing of chemicals, pharmaceuticals, petrochemicals and polymers. However, onsite monitoring of batch slurry reactions is still not feasible in production plants due to the challenge in analyzing heterogeneous samples without complicated sample preparation procedures. In this study, direct analysis in real time mass spectrometry (DART-MS) has been evaluated for the onsite monitoring of a model batch slurry reaction. The results suggested that automation of the sampling process of DART-MS is important to achieve quantitative results. With a sampling technique of manual sample deposition on melting point capillaries followed by automatic sample introduction across the helium beam, relative standard deviation (RSD) of the protonated molecule signals from the reaction product of the model batch slurry reaction ranged from 6 to 30%. This RSD range is improved greatly over a sampling technique of manual sample deposition followed by manual sample introduction where the RSDs are up to 110%. Furthermore, with the semi-automated sampling approach, semi-quantitative analysis of slurry samples has been achieved. Better quantification is expected with a fully automated sampling approach.

  17. The vinyl + NO reaction : determining the products with time-resolved Fourier transform spectroscopy.

    SciTech Connect

    Osborn, David L; Zou, Peng; Klippenstein, Stephen J.

    2005-01-01

    We have studied the vinyl + NO reaction using time-resolved Fourier transform emission spectroscopy, complemented by electronic structure and microcanonical RRKM rate coefficient calculations. To unambiguously determine the reaction products, three precursors are used to produce the vinyl radical by laser photolysis: vinyl bromide, methyl vinyl ketone, and vinyl iodide. The emission spectra and theoretical calculations indicate that HCN + CH{sub 2}O is the only significant product channel for the C{sub 2}H{sub 3} + NO reaction near room temperature, in contradiction to several reports in the literature. Although CO emission is observed when vinyl bromide is used as the precursor, it arises from the reaction of NO with photofragments other than vinyl. This conclusion is supported by the absence of CO emission when vinyl iodide or methyl vinyl ketone is used. Prompt emission from vibrationally excited NO is evidence of the competition between back dissociation and isomerization of the initially formed nitrosoethylene adduct, consistent with previous work on the pressure dependence of this reaction. Our calculations indicate that production of products is dominated by the low energy portion of the energy distribution. The calculation also predicts an upper bound of 0.19% for the branching ratio of the H{sub 2}CNH + CO channel, which is consistent with our experimental results.

  18. The effect of repetitive ankle perturbations on muscle reaction time and muscle activity.

    PubMed

    Thain, Peter Kevin; Hughes, Gerwyn Trefor Gareth; Mitchell, Andrew Charles Stephen

    2016-10-01

    The use of a tilt platform to simulate a lateral ankle sprain and record muscle reaction time is a well-established procedure. However, a potential caveat is that repetitive ankle perturbation may cause a natural attenuation of the reflex latency and amplitude. This is an important area to investigate as many researchers examine the effect of an intervention on muscle reaction time. Muscle reaction time, peak and average amplitude of the peroneus longus and tibialis anterior in response to a simulated lateral ankle sprain (combined inversion and plantar flexion movement) were calculated in twenty-two physically active participants. The 40 perturbations were divided into 4 even groups of 10 dominant limb perturbations. Within-participants repeated measures analysis of variance (ANOVA) tests were conducted to assess the effect of habituation over time for each variable. There was a significant reduction in the peroneus longus average amplitude between the aggregated first and last 10 consecutive ankle perturbations (F2.15,45.09=3.90, P=0.03, ɳp(2)=0.16). Authors should implement no more than a maximum of 30 consecutive ankle perturbations (inclusive of practice perturbations) in future protocols simulating a lateral ankle sprain in an effort to avoid significant attenuation of muscle activity.

  19. Mass action realizations of reaction kinetic system models on various time scales

    NASA Astrophysics Data System (ADS)

    Hangos, K. M.; Szederkényi, G.

    2011-01-01

    Complex chemical reaction networks often exhibit different dynamic behaviour on different time scales. A combined approach is proposed in this work for determining physically meaningful mass action realizations of complex chemical reaction networks that describe its dynamic behaviour on different time scales. This is achieved by appropriately reducing the detailed overall mass action kinetic scheme using quasi steady state assumptions fit to the particular time scale, and then searching for an optimal realization using mixed integer linear programing. Furthermore, the relationship between the properties (reversibility, deficiency, stability) of the obtained realizations of the same system on different time scales are also investigated and related to the same properties of the detailed overall model. It is shown that the reduced models obtained by quasi steady state assumptions may show exotic nonlinear behaviour, such as oscillations, when the original detailed is globally asymptotically stable. The proposed methods are illustrated by using a simple Michaelis-Menten type reaction kinetic example. The simplified versions of the well known Brusselator model have also been investigated and presented as a case study.

  20. Ring-closing metathesis reactions: interpretation of conversion-time data.

    PubMed

    Thiel, Vasco; Wannowius, Klaus-Jürgen; Wolff, Christiane; Thiele, Christina M; Plenio, Herbert

    2013-11-25

    Conversion-time data were recorded for various ring-closing metathesis (RCM) reactions that lead to five- or six-membered cyclic olefins by using different precatalysts of the Hoveyda type. Slowly activated precatalysts were found to produce more RCM product than rapidly activated complexes, but this comes at the price of slower product formation. A kinetic model for the analysis of the conversion-time data was derived, which is based on the conversion of the precatalyst (Pcat) into the active species (Acat), with the rate constant k(act), followed by two parallel reactions: 1) the catalytic reaction, which utilizes Acat to convert reactants into products, with the rate k(cat), and 2) the conversion of Acat into the inactive species (Dcat), with the rate k(dec). The calculations employ two experimental parameters: the concentration of the substrate (c(S)) at a given time and the rate of substrate conversion (-dc(S)/dt). This provides a direct measure of the concentration of Acat and enables the calculation of the pseudo-first-order rate constants k(act), k(cat), and k(dec) and of k(S) (for the RCM conversion of the respective substrate by Acat). Most of the RCM reactions studied with different precatalysts are characterized by fast k(cat) rates and by the k(dec) value being greater than the k(act) value, which leads to quasistationarity for Acat. The active species formed during the activation step was shown to be the same, regardless of the nature of different Pcats. The decomposition of Acat occurs along two parallel pathways, a unimolecular (or pseudo-first-order) reaction and a bimolecular reaction involving two ruthenium complexes. Electron-deficient precatalysts display higher rates of catalyst deactivation than their electron-rich relatives. Slowly initiating Pcats act as a reservoir, by generating small stationary concentrations of Acat. Based on this, it can be understood why the use of different precatalysts results in different substrate conversions in

  1. The Effect of Lateral Ankle Ligament Repair in Muscle Reaction Time in Patients with Mechanical Ankle Instability.

    PubMed

    Li, H-Y; Zheng, J-J; Zhang, J; Hua, Y-H; Chen, S-Y

    2015-11-01

    Studies have shown that functional ankle instability can result in prolonged muscle reaction time. However, the deficit in muscle reaction time in patients with mechanical ankle instability (MAI) and the effect of lateral ankle ligament repair on muscle reaction time are unclear. The purpose of this study was to identify the deficit in muscle reaction time, and to evaluate the role of lateral ligament repair in improving muscle reaction time in MAI patients. Sixteen MAI patients diagnosed with lateral ankle ligament tears by ultrasonography and magnetic resonance imaging underwent arthroscopic debridement and open lateral ankle ligament repair with a modified Broström procedure. One day before the operation, reaction times of the tibialis anterior and peroneus longus muscles were recorded following sudden inversion perturbation while walking on a custom walkway, and anterior drawer test (ADT) and American Orthopaedic Foot and Ankle Society (AOFAS) scale score were evaluated. Six months postoperatively, muscle reaction time, ADT and AOFAS scale score were reevaluated, and muscle reaction times in 15 healthy controls were also recorded. Preoperatively, the affected ankles in the MAI group had significantly delayed tibialis anterior and peroneus longus muscles reaction times compared with controls. Six months after the operation, median AOFAS scale scores were significantly greater than preoperatively, and ADT was negative in the MAI group. However, the affected ankles in the MAI group showed no difference in muscle reaction time compared with preoperative values. MAI patients had prolonged muscle reaction time. The modified Broström procedure produced satisfactory clinical outcomes in MAI patients, but did not shorten reaction times of the tibialis anterior and peroneus longus muscles.

  2. [Influence of Reaction Time on Titanate Nanomaterials and Its Adsorptioi Capability for Lead in Aqueous Solutions].

    PubMed

    Fan, Gong-duan; Chen, Li-ru; Lin, Ru-jing; Lin, Qian; Su, Zhao-yue; Lin, Xiu-yong

    2016-02-15

    Titanate nanomaterials (TNs) were synthesized via a simple hydrothermal method using TiO2 (ST-01) and NaOH as the raw materials, and presented different morphologies by adjusting the reaction time. The physico-chemical properties of the as-prepared TNs, such as morphology, structure, surface area, and chemical composition were characterized by XRD, SEM and BET. The adsorption capability and rules of Pb(II) in aqueous solutions were tested in the static system. The results showed that the TNs prepared with 12-72 h reaction time were pure monoclinic phase titanate and their specific surface areas were in the range from 243.05 m2 x g(-1) to 286.20 m2 x g(-1). TNs with reaction time between 12-36 h mainly showed sheet structure, and those with reaction time higher than 48 h showed linear structure. The adsorption capacity of Pb(II) by TNs-12, TNs-24, TNs-36, TNs-48, TNs-60 and TNs-72 was 479.40, 504.12, 482.00, 388.10, 364.60 and 399.00 mg x g(-1), respectively. The sheet TNs had a better adsorption capacity than the linear TNs. TNs-24 had the highest adsorbing capacity. The adsorption kinetics of Pb(II) by TNs-24 followed the pseudo-second-order model, and the equilibrium data was best fitted with the Langmuir isotherm model. The equilibrium adsorption time of TNs-24 was 120 min, and the adsorption was an exothermic process, with a high adsorption capacity at low temperature or room temperature; the optimal adsorption pH was 5.0. When pH was 1.0, the desorption rate of TNs-24 could reach 99.00%, and the removal efficiency of Pb(II) by regenerated TNs was still more than 97% after six times of usage. Therefore, TNs could efficiently remove Pb(II) in aqueous solutions, and the optimal reaction time should be controlled to 12-24 h. When Cd(II) or Ni(II) existed in the solution, the equilibrium adsorption capacity and removal rate of TNs-24 were decreased. The adsorption mechanism was mainly ion-exchanged between Pb(II) and H+/Na+ in TNs.

  3. [Influence of Reaction Time on Titanate Nanomaterials and Its Adsorptioi Capability for Lead in Aqueous Solutions].

    PubMed

    Fan, Gong-duan; Chen, Li-ru; Lin, Ru-jing; Lin, Qian; Su, Zhao-yue; Lin, Xiu-yong

    2016-02-15

    Titanate nanomaterials (TNs) were synthesized via a simple hydrothermal method using TiO2 (ST-01) and NaOH as the raw materials, and presented different morphologies by adjusting the reaction time. The physico-chemical properties of the as-prepared TNs, such as morphology, structure, surface area, and chemical composition were characterized by XRD, SEM and BET. The adsorption capability and rules of Pb(II) in aqueous solutions were tested in the static system. The results showed that the TNs prepared with 12-72 h reaction time were pure monoclinic phase titanate and their specific surface areas were in the range from 243.05 m2 x g(-1) to 286.20 m2 x g(-1). TNs with reaction time between 12-36 h mainly showed sheet structure, and those with reaction time higher than 48 h showed linear structure. The adsorption capacity of Pb(II) by TNs-12, TNs-24, TNs-36, TNs-48, TNs-60 and TNs-72 was 479.40, 504.12, 482.00, 388.10, 364.60 and 399.00 mg x g(-1), respectively. The sheet TNs had a better adsorption capacity than the linear TNs. TNs-24 had the highest adsorbing capacity. The adsorption kinetics of Pb(II) by TNs-24 followed the pseudo-second-order model, and the equilibrium data was best fitted with the Langmuir isotherm model. The equilibrium adsorption time of TNs-24 was 120 min, and the adsorption was an exothermic process, with a high adsorption capacity at low temperature or room temperature; the optimal adsorption pH was 5.0. When pH was 1.0, the desorption rate of TNs-24 could reach 99.00%, and the removal efficiency of Pb(II) by regenerated TNs was still more than 97% after six times of usage. Therefore, TNs could efficiently remove Pb(II) in aqueous solutions, and the optimal reaction time should be controlled to 12-24 h. When Cd(II) or Ni(II) existed in the solution, the equilibrium adsorption capacity and removal rate of TNs-24 were decreased. The adsorption mechanism was mainly ion-exchanged between Pb(II) and H+/Na+ in TNs. PMID:27363159

  4. Variability of single trial brain activation predicts fluctuations in reaction time.

    PubMed

    Bender, Stephan; Banaschewski, Tobias; Roessner, Veit; Klein, Christoph; Rietschel, Marcella; Feige, Bernd; Brandeis, Daniel; Laucht, Manfred

    2015-03-01

    Brain activation stability is crucial to understanding attention lapses. EEG methods could provide excellent markers to assess neuronal response variability with respect to temporal (intertrial coherence) and spatial variability (topographic consistency) as well as variations in activation intensity (low frequency variability of single trial global field power). We calculated intertrial coherence, topographic consistency and low frequency amplitude variability during target P300 in a continuous performance test in 263 15-year-olds from a cohort with psychosocial and biological risk factors. Topographic consistency and low frequency amplitude variability predicted reaction time fluctuations (RTSD) in a linear model. Higher RTSD was only associated with higher psychosocial adversity in the presence of the homozygous 6R-10R dopamine transporter haplotype. We propose that topographic variability of single trial P300 reflects noise as well as variability in evoked cortical activation patterns. Dopaminergic neuromodulation interacted with environmental and biological risk factors to predict behavioural reaction time variability.

  5. Survival is linked with reaction time and spatial memory in African striped mice.

    PubMed

    Maille, Audrey; Schradin, Carsten

    2016-08-01

    Studying the association between fitness and cognition in free-living animals is a fundamental step in the elucidation of the evolution of cognition. We assessed whether survival until the onset of the breeding season was related to reaction time or spatial memory in the African striped mouse Rhabdomys pumilio, a rodent that has to survive summer drought before breeding. We tested a total of 90 individuals at the beginning of summer. Female survival was related to a faster response to predation stimuli. Male survival increased with greater spatial memory, possibly because it is important for males to remember the configuration of the environment during dispersal. This study revealed that individual variation in reaction time and spatial memory can be related to survival probability, which is important for understanding the selection pressures acting on basic cognitive traits. PMID:27484646

  6. Dependecy of the reaction time from the overlap of signal lights with different colors

    NASA Astrophysics Data System (ADS)

    Klinger, Karsten D.

    2005-02-01

    The rearward signal aspect consists of lights with different colors. With standard technics these signal lights are located at different places. With new technics it is possible to build signal lights with different colors together in one place. The signals overlap. In experiments at the University of Karlsruhe we studied the dependency between reaction time and overlap of signal lights. We can see, that the total overlap from a yellow turn signal and a red brake signal will increase the reaction time. The increase depends of the ratio between the luminance of the turn indicator signal and the luminance of the brake signal. With a ratio from one to one (best case with minimal increase) we found an increase of 300 milli seconds.

  7. The effect of feedback schedule manipulation on speech priming patterns and reaction time.

    PubMed

    Slocomb, Dana; Spencer, Kristie A

    2009-02-01

    Speech priming tasks are frequently used to delineate stages in the speech process such as lexical retrieval and motor programming. These tasks, often measured in reaction time (RT), require fast and accurate responses, reflecting maximized participant performance, to result in robust priming effects. Encouraging speed and accuracy in responding can take many forms, including verbal instructions and feedback, and often involves visually displayed RT feedback. However, it is uncertain how manipulation of the schedule of this RT feedback influences speech RT speed and, ultimately, the priming effect. This experiment examined the effect of visually presented RT feedback schedules on priming patterns in 20 older healthy adults. Results suggested that feedback schedule manipulation had a differential effect on reaction time, depending on the interstimulus interval between the prime and the target, but no effect on response priming patterns.

  8. Reaction time inconsistency in a spatial stroop task: age-related differences through childhood and adulthood.

    PubMed

    Williams, Benjamin R; Strauss, Esther H; Hultsch, David F; Hunter, Michael A

    2007-07-01

    Age-related differences in inconsistency of reaction time (RT) across the life span were examined on a task with differing levels of demand on executive control. A total of 546 participants, aged 5 to 76 years, completed a spatial Stroop task that permitted observations under three conditions (congruent, incongruent, and neutral) according to the correspondence between the required response (based on stimulus direction) and stimulus location. An interference effect was observed across all ages. Analyses of neutral condition data replicated previous research demonstrating RT inconsistency follows a U-shaped developmental curve across the life span. The relationship between age and inconsistency, however, depended on condition: inconsistency in the congruent condition was higher than inconsistency in both the neutral and incongruent conditions across middle-aged groups. Reaction time inconsistency may reflect processing efficiency that is maximal in young adulthood and may also be sensitive to fluctuations in performance that reflect momentarily highly efficient responding.

  9. Real-Time Reverse Transcription–Polymerase Chain Reaction Assay for SARS-associated Coronavirus

    PubMed Central

    Emery, Shannon L.; Bowen, Michael D.; Newton, Bruce R.; Winchell, Jonas M.; Meyer, Richard F.; Tong, Suxiang; Cook, Byron T.; Holloway, Brian P.; McCaustland, Karen A.; Rota, Paul A.; Bankamp, Bettina; Lowe, Luis E.; Ksiazek, Tom G.; Bellini, William J.; Anderson, Larry J.

    2004-01-01

    A real-time reverse transcription–polymerase chain reaction (RT-PCR) assay was developed to rapidly detect the severe acute respiratory syndrome–associated coronavirus (SARS-CoV). The assay, based on multiple primer and probe sets located in different regions of the SARS-CoV genome, could discriminate SARS-CoV from other human and animal coronaviruses with a potential detection limit of <10 genomic copies per reaction. The real-time RT-PCR assay was more sensitive than a conventional RT-PCR assay or culture isolation and proved suitable to detect SARS-CoV in clinical specimens. Application of this assay will aid in diagnosing SARS-CoV infection. PMID:15030703

  10. Reaction time and onset of psychological distress: the UK Health and Lifestyle Survey

    PubMed Central

    Gale, Catharine R; Harris, Alicia; Deary, Ian J

    2016-01-01

    Background Cross-sectional studies have shown that depression is often accompanied by less efficient cognitive function, as indicated by slower speed of information processing. The direction of effect is unclear. We investigated prospectively whether slower processing speed, as indexed by longer simple or choice reaction time, is associated with an increased risk of psychological distress. Methods Participants were 3088 men and women aged 18 and over who had taken part in the UK Health and Lifestyle Survey. Simple and choice reaction time was measured in the baseline survey. Symptoms of psychological distress were assessed at baseline and at the 7-year follow-up survey with the 30-item General Health Questionnaire (GHQ). Results In unadjusted models, a SD slower simple or choice reaction time at baseline was associated with ORs for psychological distress (≥5 on GHQ) at follow-up of 1.14 (1.06 to 1.23; p<0.001) or 1.13 (1.04 to 1.22; p=0.002), respectively. Further adjustment for age, sex, social class, educational attainment, health behaviours, number of chronic physical illnesses present, neuroticism and GHQ score at baseline had only slight attenuating effects on these associations. In fully adjusted models, a SD slower simple or choice reaction time at baseline was associated with ORs for psychological distress of 1.11 (1.02 to 1.21; p=0.017) or 1.11 (1.00 to 1.24; p=0.048), respectively. Conclusions Slower processing speed may be a risk factor for the development of psychological distress. Future studies should explore the extent to which slower processing speed explains previously demonstrated associations between lower intelligence and poorer mental health. PMID:26847135

  11. DHA- Rich Fish Oil Improves Complex Reaction Time in Female Elite Soccer Players

    PubMed Central

    Guzmán, José F.; Esteve, Hector; Pablos, Carlos; Pablos, Ana; Blasco, Cristina; Villegas, José A.

    2011-01-01

    Omega-3 fatty acids (n-3) has shown to improve neuromotor function. This study examined the effects of docosahexaenoic acid (DHA) on complex reaction time, precision and efficiency, in female elite soccer players. 24 players from two Spanish female soccer Super League teams were randomly selected and assigned to two experimental groups, then administered, in a double-blind manner, 3.5 g·day-1 of either DHA-rich fish oil (FO =12) or olive oil (OO = 12) over 4 weeks of training. Two measurements (pre- and post-treatment) of complex reaction time and precision were taken. Participants had to press different buttons and pedals with left and right hands and feet, or stop responding, according to visual and auditory stimuli. Multivariate analysis of variance displayed an interaction between supplement administration (pre/post) and experimental group (FO/OO) on complex reaction time (FO pre = 0.713 ± 0.142 ms, FO post = 0.623 ± 0.109 ms, OO pre = 0.682 ± 1.132 ms, OO post = 0.715 ± 0.159 ms; p = 0.004) and efficiency (FO pre = 40.88 ± 17.41, FO post = 57.12 ± 11.05, OO pre = 49.52 ± 14.63, OO post = 49. 50 ± 11.01; p = 0.003). It was concluded that after 4 weeks of supplementation with FO, there was a significant improvement in the neuromotor function of female elite soccer players. Key points The results obtained from the study suggest that supplementation with DHA produced perceptual-motor benefits in female elite athletes. DHA could be a beneficial supplement in sports where decision making and reaction time efficiency are of importance. PMID:24149875

  12. Analysis of Reaction Times and Aerobic Capacities of Soccer Players According to Their Playing Positions

    ERIC Educational Resources Information Center

    Taskin, Cengiz; Karakoc, Onder; Taskin, Mine; Dural, Murat

    2016-01-01

    70 soccer players in Gaziantep amateur league voluntarily participated in this study, (average of their ages 19,17±1,34years, average of their heights 181,28±5,06 cm, average of their body weights 76,75±4,43 kg and average of their sports experiences 3,78±0,95 years) to analyze visual and auditory reaction times and aerobic capacities of amateur…

  13. SEPARABLE RESPONSES TO ERROR, AMBIGUITY, AND REACTION TIME IN CINGULO-OPERCULAR TASK CONTROL REGIONS

    PubMed Central

    Neta, Maital; Schlaggar, Bradley L.; Petersen, Steven E.

    2014-01-01

    The dorsal anterior cingulate (dACC), along with the closely affiliated anterior insula/frontal operculum have been demonstrated to show three types of task control signals across a wide variety of tasks. One of these signals, a transient signal that is thought to represent performance feedback, shows greater activity to error than correct trials. Other work has found similar effects for uncertainty/ambiguity or conflict, though some argue that dACC activity is, instead, modulated primarily by other processes more reflected in reaction time. Here, we demonstrate that, rather than a single explanation, multiple information processing operations are crucial to characterizing the function of these brain regions, by comparing operations within a single paradigm. Participants performed two tasks in an fMRI experimental session: (1) deciding whether or not visually presented word pairs rhyme, and (2) rating auditorily presented single words as abstract or concrete. A pilot was used to identify ambiguous stimuli for both tasks (e.g., word pair: BASS/GRACE; single word: CHANGE). We found greater cingulo-opercular activity for errors and ambiguous trials than clear/correct trials, with a robust effect of reaction time. The effects of error and ambiguity remained when reaction time was regressed out, although the differences decreased. Further stepwise regression of response consensus (agreement across participants for each stimulus; a proxy for ambiguity) decreased differences between ambiguous and clear trials, but left error-related differences almost completely intact. These observations suggest that trial-wise responses in cinguloopercular regions monitor multiple performance indices, including accuracy, ambiguity, and reaction time. PMID:24887509

  14. Reaction time of voluntary modulations in voice F0 during sustained pitch vocalizations

    NASA Astrophysics Data System (ADS)

    Bauer, Jay J.; Larson, Charles R.; Eckstein, Kathryn C.

    2002-05-01

    In an attempt to more clearly understand the neural control of voice, a reaction time study was designed to investigate how rapidly normal subjects, i.e., nontrained singers, can voluntarily increase or decrease their voice fundamental frequency (F0) during sustained vocalizations when cued with a 1000-Hz auditory tone stimulus. Results revealed that overall reaction times (RTs) (F=21.9, df=2, 150, p=0.01) for upward F0 modulations occurred faster (range: 138-176 ms) than downward responses (range: 196-234 ms). In contrast to the reaction time findings, slightly higher peak velocities were observed for downward responses compared to upward responses. Shorter RTs observed for F0 elevation are therefore possibly related to central mechanisms involved in the planning of or execution of the direction in which F0 is to be modulated instead of muscle biomechanics. The fastest RTs obtained from the present study (138 ms) are slightly longer than the reflex latencies of the initial pitch-shift reflex response (100-130 ms) [Burnett, J. Acoust. Soc. Am. 103 (1998)], and provide additional evidence that subjects normally respond to inadvertent changes in their voice F0 with a fast, but limited reflex, followed by a secondary voluntary response. [Research supported by NIH Grant No. DC07264.

  15. Preparatory delay activity in the monkey parietal reach region predicts reach reaction times.

    PubMed

    Snyder, Lawrence H; Dickinson, Anthony R; Calton, Jeffrey L

    2006-10-01

    To acquire something that we see, visual spatial information must ultimately result in the activation of the appropriate set of muscles. This sensory to motor transformation requires an interaction between information coding target location and information coding which effector will be moved. Activity in the monkey parietal reach region (PRR) reflects both spatial information and the effector (arm or eye) that will be used in an upcoming reach or saccade task. To further elucidate the functional role of PRR in visually guided movement tasks and to obtain evidence that PRR signals are used to drive arm movements, we tested the hypothesis that increased neuronal activity during a preparatory delay period would lead to faster reach reaction times but would not be correlated with saccade reaction times. This proved to be the case only when the type of movement and not the spatial goal of that movement was known in advance. The correlation was strongest in cells that showed significantly more activity on arm reach compared with saccade trials. No significant correlations were found during delay periods in which spatial information was provided in advance. These data support the idea that PRR constitutes a bottleneck in the processing of spatial information for an upcoming arm reach. The lack of a correlation with saccadic reaction time also supports the idea that PRR processing is effector specific, that is, it is involved in specifying targets for arm movements but not targets for eye movements.

  16. Fast reducers, slow augmenters: a psychophysiological analysis of temperament-related differences in reaction time.

    PubMed

    Schwerdtfeger, Andreas; Getzmann, Stephan; Baltissen, Rüdiger

    2004-05-01

    Augmenting-reducing theory describes temperament-related differences in the modulation of stimulation. Reducers are supposed to need more stimulation than augmenters because of a cortical attenuation of incoming stimuli. The study investigated differences between augmenters and reducers (classified by questionnaire) in performance and information processing strategies in a simple reaction time task. Fifty-two subjects (27 augmenters, 25 reducers) took part in a visual reaction time task with go- and catch-trials (30%). Reaction times, commission errors, and psychophysiological indicators of information processing (N1, P300, EMG) were recorded. Reducers were faster and exhibited more commission errors than augmenters. Moreover, reducers exhibited higher N1-amplitudes, faster EMG-onsets and higher EMG-amplitudes than augmenters. An additional pain tolerance test revealed that male reducers were more pain tolerant than the other participants. These results are consistent with the proposition that reducers have a higher need for stimulation than augmenters. Probably, they utilize locomotor activity in order to compensate for their attenuated arousal.

  17. A continuous-flow capillary mixing method to monitor reactions on the microsecond time scale.

    PubMed

    Shastry, M C; Luck, S D; Roder, H

    1998-05-01

    A continuous-flow capillary mixing apparatus, based on the original design of Regenfuss et al. (Regenfuss, P., R. M. Clegg, M. J. Fulwyler, F. J. Barrantes, and T. M. Jovin. 1985. Rev. Sci. Instrum. 56:283-290), has been developed with significant advances in mixer design, detection method and data analysis. To overcome the problems associated with the free-flowing jet used for observation in the original design (instability, optical artifacts due to scattering, poor definition of the geometry), the solution emerging from the capillary is injected directly into a flow-cell joined to the tip of the outer capillary via a ground-glass joint. The reaction kinetics are followed by measuring fluorescence versus distance downstream from the mixer, using an Hg(Xe) arc lamp for excitation and a digital camera with a UV-sensitized CCD detector for detection. Test reactions involving fluorescent dyes indicate that mixing is completed within 15 micros of its initiation and that the dead time of the measurement is 45 +/- 5 micros, which represents a >30-fold improvement in time resolution over conventional stopped-flow instruments. The high sensitivity and linearity of the CCD camera have been instrumental in obtaining artifact-free kinetic data over the time window from approximately 45 micros to a few milliseconds with signal-to-noise levels comparable to those of conventional methods. The scope of the method is discussed and illustrated with an example of a protein folding reaction.

  18. Changes in Practice Schedule and Functional Task Difficulty: a Study Using the Probe Reaction Time Technique

    PubMed Central

    Akizuki, Kazunori; Ohashi, Yukari

    2013-01-01

    [Purpose] Motor learning is accelerated most by optimized task difficulty. When task difficulty is optimized, the amount of information required to complete the task matches the learner's information processing abilities. The practice schedule is one of the factors which changes the amount of task information. We investigated the influence of changes in practice schedule on the amount of task information using the probe reaction time technique. [Methods] Fourteen young male subjects were randomly assigned to a blocked or random practice group. They were required to perform two tasks simultaneously. The primary task consisted of treadmill walking with specific step lengths, and the secondary task consisted of a probe reaction time task. [Results] The blocked practice group was superior to the random practice group in performance during the acquisition phase. In contrast, the random practice group was superior to the blocked practice group in performance during the retention phase. Furthermore, the random practice group had a longer reaction time than the blocked practice group. [Conclusion] From the standpoint of the challenge point framework, motor learning may be accelerated by random practice because random practice probably elicits greater attentional demand than blocked practice. PMID:24259863

  19. Analysis of the HindIII-catalyzed reaction by time-resolved crystallography

    SciTech Connect

    Kawamura, Takashi; Kobayashi, Tomoki; Watanabe, Nobuhisa

    2015-02-01

    A time-resolved study using the freeze-trap method elucidates the mechanism of the DNA-cleaving reaction of HindIII. In order to investigate the mechanism of the reaction catalyzed by HindIII, structures of HindIII–DNA complexes with varying durations of soaking time in cryoprotectant buffer containing manganese ions were determined by the freeze-trap method. In the crystal structures of the complexes obtained after soaking for a longer duration, two manganese ions, indicated by relatively higher electron density, are clearly observed at the two metal ion-binding sites in the active site of HindIII. The increase in the electron density of the two metal-ion peaks followed distinct pathways with increasing soaking times, suggesting variation in the binding rate constant for the two metal sites. DNA cleavage is observed when the second manganese ion appears, suggesting that HindIII uses the two-metal-ion mechanism, or alternatively that its reactivity is enhanced by the binding of the second metal ion. In addition, conformational change in a loop near the active site accompanies the catalytic reaction.

  20. Dissolution Dynamic Nuclear Polarization Instrumentation for Real-time Enzymatic Reaction Rate Measurements by NMR.

    PubMed

    Balzan, Riccardo; Fernandes, Laetitia; Comment, Arnaud; Pidial, Laetitia; Tavitian, Bertrand; Vasos, Paul R

    2016-01-01

    The main limitation of NMR-based investigations is low sensitivity. This prompts for long acquisition times, thus preventing real-time NMR measurements of metabolic transformations. Hyperpolarization via dissolution DNP circumvents part of the sensitivity issues thanks to the large out-of-equilibrium nuclear magnetization stemming from the electron-to-nucleus spin polarization transfer. The high NMR signal obtained can be used to monitor chemical reactions in real time. The downside of hyperpolarized NMR resides in the limited time window available for signal acquisition, which is usually on the order of the nuclear spin longitudinal relaxation time constant, T1, or, in favorable cases, on the order of the relaxation time constant associated with the singlet-state of coupled nuclei, TLLS. Cellular uptake of endogenous molecules and metabolic rates can provide essential information on tumor development and drug response. Numerous previous hyperpolarized NMR studies have demonstrated the relevancy of pyruvate as a metabolic substrate for monitoring enzymatic activity in vivo. This work provides a detailed description of the experimental setup and methods required for the study of enzymatic reactions, in particular the pyruvate-to-lactate conversion rate in presence of lactate dehydrogenase (LDH), by hyperpolarized NMR. PMID:26967906

  1. 6-hydroxydopamine lesions in the rat neostriatum impair sequential learning in a serial reaction time task.

    PubMed

    Eckart, Moritz Thede; Huelse-Matia, Moriah Christina; McDonald, Rebecca S; Schwarting, Rainer K -W

    2010-04-01

    Sequential behavior has been intensively investigated in humans using so-called serial reaction time tasks(SRTT), in which visual stimuli are either presented in a random or sequential order. Typically, when the stimulus presentation follows a previously learned sequential order,reaction times are decreased compared to random stimulus presentation and become partly automated. A vast amount of SRTT findings indicates that sequential learning and performance seem to be mediated amongst others by the basal ganglia-especially the striatum-and the neurotransmitter dopamine therein. In this study we used an operant rat version of the human four choice SRTT to investigate the effect of bilateral neostriatal dopamine lesions induced by 6-hydroxydopamine on sequential learning. The rats' task was to respond rapidly to illuminated holes by nose-poking into them. During extensive training, the position of the illuminated hole followed a 12-item sequence. The outcome of this sequential training was also investigated in two tests, namely an interference test, where stimulus presentation switched between this sequential and a pseudo random order every five minutes, and a violation test, in which only one sequence item was eventually skipped. The neurotoxic lesions, which was placed before the start of training, led to the expected sub-total dopamine depletions (i.e. residual levels around 34-56% of controls), especially in the medial neostriatum. These lesions did not lead to general motor deficits in a catalepsy task, but moderate deficits in locomotion in an activity box, which largely recovered with time after lesion. In the SRTT, rats with lesions showed impaired learning, that is, less response accuracy and slower reaction times than the control group.During a subsequent test with alternating phases of sequential and random stimulus presentations, reaction times and accuracy of the control group were superior during sequential as compared to random stimulus phases. In the

  2. Designing Driver Assistance Systems with Crossmodal Signals: Multisensory Integration Rules for Saccadic Reaction Times Apply

    PubMed Central

    Steenken, Rike; Weber, Lars; Colonius, Hans; Diederich, Adele

    2014-01-01

    Modern driver assistance systems make increasing use of auditory and tactile signals in order to reduce the driver's visual information load. This entails potential crossmodal interaction effects that need to be taken into account in designing an optimal system. Here we show that saccadic reaction times to visual targets (cockpit or outside mirror), presented in a driving simulator environment and accompanied by auditory or tactile accessories, follow some well-known spatiotemporal rules of multisensory integration, usually found under confined laboratory conditions. Auditory nontargets speed up reaction time by about 80 ms. The effect tends to be maximal when the nontarget is presented 50 ms before the target and when target and nontarget are spatially coincident. The effect of a tactile nontarget (vibrating steering wheel) was less pronounced and not spatially specific. It is shown that the average reaction times are well-described by the stochastic “time window of integration” model for multisensory integration developed by the authors. This two-stage model postulates that crossmodal interaction occurs only if the peripheral processes from the different sensory modalities terminate within a fixed temporal interval, and that the amount of crossmodal interaction manifests itself in an increase or decrease of second stage processing time. A qualitative test is consistent with the model prediction that the probability of interaction, but not the amount of crossmodal interaction, depends on target–nontarget onset asynchrony. A quantitative model fit yields estimates of individual participants' parameters, including the size of the time window. Some consequences for the design of driver assistance systems are discussed. PMID:24800823

  3. Time-resolved infrared absorption studies of the dynamics of radical reactions.

    SciTech Connect

    Macdonald, R. G.

    2008-01-01

    There is very little information available about the dynamics of radical+radical interactions. These processes are important in combustion being chain termination steps as well as generating new molecular species. To study these processes, a new experimental apparatus has been constructed to investigate radical-radical dynamics. The first radical or atomic species is produced with a known concentration in a microwave discharge flow system. The second is produced by pulsed laser photolysis of a suitable photolyte. The time dependence of individual rovibrational states of the product is followed by absorption of a continuous infrared laser. This approach will allow the reaction of interest to be differentiated from other radical reactions occurring simultaneously. The experimental approach is highly versatile, being able to detect a number of molecular species of particular interest to combustion processes such as water, methane, acetylene etc. at the state specific level. State specific infrared absorption coefficients of radicals can be measured in situ allowing for the determination of the absolute concentrations and hence branching ratios for reactions having multiple reaction pathways.

  4. Time variation in the reaction-zone structure of two-phase spray detonations.

    NASA Technical Reports Server (NTRS)

    Pierce, T. H.; Nicholls, J. A.

    1973-01-01

    A detailed theoretical analysis of the time-varying detonation structure in a monodisperse spray is presented. The theory identifies experimentally observed reaction-zone overpressures as deriving from blast waves formed therein by the explosive ignition of the spray droplets, and follows in time the motion, change in strength, and interactions of these blast waves with one another, and with the leading shock. The results are compared with experimental data by modeling the motion of a finite-size circular pressure transducer through the theoretical data field in an x-t space.

  5. Time-resolved circular dichroism and absorption studies of the photolysis reaction of (carbonmonoxy)myoglobin.

    PubMed Central

    Milder, S J; Bjorling, S C; Kuntz, I D; Kliger, D S

    1988-01-01

    Time-resolved circular dichroism (TRCD) and absorption spectroscopy are used to follow the photolysis reaction of (carbonmonoxy)myoglobin (MbCO). Following the spectral changes associated with the initial loss of CO, a subtle change is observed in the visible absorption spectrum of the Mb product on a time scale of a few hundred nanoseconds. No changes are seen in the CD spectrum of Mb in the visible and near-UV regions subsequent to the loss of CO. The data suggest the existence of an intermediate found after ligand loss from MbCO that is similar in structure to the final Mb product. PMID:3390516

  6. Calculation of reaction rate constants using approximate evolution of quantum trajectories in imaginary and real time

    NASA Astrophysics Data System (ADS)

    Garashchuk, Sophya

    2010-05-01

    Reaction rate constants can be directly obtained from evolution of the flux operator eigenvectors under the Boltzmann and Hamiltonian operators. This is achieved by evolving the quantum trajectory ensemble, representing a wavefunction, in imaginary time seamlessly switching to the real-time dynamics. Quantum-mechanical effects are incorporated through the quantum potential dependent on the trajectory momenta or on the derivatives of the wavefunction amplitude. For practicality the quantum potential and wavefunction nodes are described using linear basis, which is exact for Gaussian wavefunctions. For the Eckart barrier approximate rate constants show significant improvement over the parabolic barrier rate constants.

  7. [Identification of human pathogenic variola and monkeypox viruses by real-time polymerase chain reaction].

    PubMed

    Kostina, E V; Gavrilova, E V; Riabinin, V A; Shchelkunov, S N; Siniakov, A N

    2009-01-01

    A kit of specific oligonucleotide primers and hybridization probes has been proposed to detect orthopoxviruses (OPV) and to discriminate human pathogenic viruses, such as variola virus and monkey virus by real-time polymerase chain reaction (PCR). For real-time PCR, the following pairs of fluorophore and a fluorescence quencher were used: TAMRA-BHQ2 for genus-specific probes and FAM-BHQ1 for species-specific ones (variola virus, monkeypox virus, ectomelia virus). The specificity of this assay was tested on 38 strains of 6 OPV species and it was 100%.

  8. [Real-time polymerase chain reaction in the diagnosis of pulmonary tuberculosis].

    PubMed

    Salina, T Iu; Morozova, T I

    2008-01-01

    To enhance the efficiency of diagnosis of oligo- and abacillar pulmonary tuberculosis and its differential diagnosis with other lung diseases, the authors studied the informative value of real-time polymerase chain reaction (PCR) used in 62 patients with different clinical forms of tuberculosis and 108 differentially diagnostic patients. Real-time PCR has been ascertained to be a significantly more sensitive and highly specific tool in tuberculosis diagnosis, which considerably improves the specific recognition of the etiology of a pathogenetic process in oligo- and abacillar patients. Particularly encouraging results have been obtained when examining differentially diagnostic patients with the rounded shadows being formed in the lung. PMID:18710048

  9. The Effects of Repeated Testing, Simulated Malingering, and Traumatic Brain Injury on Visual Choice Reaction Time

    PubMed Central

    Woods, David L.; Wyma, John M.; Yund, E. W.; Herron, Timothy J.

    2015-01-01

    Choice reaction time (CRT), the time required to discriminate and respond appropriately to different stimuli, is a basic measure of attention and processing speed. Here, we describe the reliability and clinical sensitivity of a new CRT test that presents lateralized visual stimuli and adaptively adjusts stimulus onset asynchronies using a staircase procedure. Experiment 1 investigated the test–retest reliability in three test sessions performed at weekly intervals. Performance in the first test session was accurately predicted from age and computer-use regression functions obtained in a previously studied normative cohort. Central processing time (CentPT), the difference between the CRTs and simple reaction time latencies measured in a separate experiment, accounted for 55% of CRT latency and more than 85% of CRT latency variance. Performance improved significantly across the three test sessions. High intraclass correlation coefficients were seen for CRTs (0.90), CentPTs (0.87), and an omnibus performance measure (0.81) that combined CRT and minimal SOA z-scores. Experiment 2 investigated performance in the same participants when instructed to feign symptoms of traumatic brain injury (TBI): 87% produced abnormal omnibus z-scores. Simulated malingerers showed greater elevations in simple reaction times than CRTs, and hence reduced CentPTs. Latency-consistency z-scores, based on the difference between the CRTs obtained and those predicted based on CentPT latencies, discriminated malingering participants from controls with high sensitivity and specificity. Experiment 3 investigated CRT test performance in military veterans who had suffered combat-related TBI and symptoms of post-traumatic stress disorder, and revealed small but significant deficits in performance in the TBI population. The results indicate that the new CRT test shows high test–retest reliability, can assist in detecting participants performing with suboptimal effort, and is sensitive to the

  10. The Effects of Repeated Testing, Simulated Malingering, and Traumatic Brain Injury on Visual Choice Reaction Time.

    PubMed

    Woods, David L; Wyma, John M; Yund, E W; Herron, Timothy J

    2015-01-01

    Choice reaction time (CRT), the time required to discriminate and respond appropriately to different stimuli, is a basic measure of attention and processing speed. Here, we describe the reliability and clinical sensitivity of a new CRT test that presents lateralized visual stimuli and adaptively adjusts stimulus onset asynchronies using a staircase procedure. Experiment 1 investigated the test-retest reliability in three test sessions performed at weekly intervals. Performance in the first test session was accurately predicted from age and computer-use regression functions obtained in a previously studied normative cohort. Central processing time (CentPT), the difference between the CRTs and simple reaction time latencies measured in a separate experiment, accounted for 55% of CRT latency and more than 85% of CRT latency variance. Performance improved significantly across the three test sessions. High intraclass correlation coefficients were seen for CRTs (0.90), CentPTs (0.87), and an omnibus performance measure (0.81) that combined CRT and minimal SOA z-scores. Experiment 2 investigated performance in the same participants when instructed to feign symptoms of traumatic brain injury (TBI): 87% produced abnormal omnibus z-scores. Simulated malingerers showed greater elevations in simple reaction times than CRTs, and hence reduced CentPTs. Latency-consistency z-scores, based on the difference between the CRTs obtained and those predicted based on CentPT latencies, discriminated malingering participants from controls with high sensitivity and specificity. Experiment 3 investigated CRT test performance in military veterans who had suffered combat-related TBI and symptoms of post-traumatic stress disorder, and revealed small but significant deficits in performance in the TBI population. The results indicate that the new CRT test shows high test-retest reliability, can assist in detecting participants performing with suboptimal effort, and is sensitive to the effects of

  11. Mathematical Modeling and Dynamic Simulation of Metabolic Reaction Systems Using Metabolome Time Series Data

    PubMed Central

    Sriyudthsak, Kansuporn; Shiraishi, Fumihide; Hirai, Masami Yokota

    2016-01-01

    The high-throughput acquisition of metabolome data is greatly anticipated for the complete understanding of cellular metabolism in living organisms. A variety of analytical technologies have been developed to acquire large-scale metabolic profiles under different biological or environmental conditions. Time series data are useful for predicting the most likely metabolic pathways because they provide important information regarding the accumulation of metabolites, which implies causal relationships in the metabolic reaction network. Considerable effort has been undertaken to utilize these data for constructing a mathematical model merging system properties and quantitatively characterizing a whole metabolic system in toto. However, there are technical difficulties between benchmarking the provision and utilization of data. Although, hundreds of metabolites can be measured, which provide information on the metabolic reaction system, simultaneous measurement of thousands of metabolites is still challenging. In addition, it is nontrivial to logically predict the dynamic behaviors of unmeasurable metabolite concentrations without sufficient information on the metabolic reaction network. Yet, consolidating the advantages of advancements in both metabolomics and mathematical modeling remain to be accomplished. This review outlines the conceptual basis of and recent advances in technologies in both the research fields. It also highlights the potential for constructing a large-scale mathematical model by estimating model parameters from time series metabolome data in order to comprehensively understand metabolism at the systems level. PMID:27200361

  12. Mathematical Modeling and Dynamic Simulation of Metabolic Reaction Systems Using Metabolome Time Series Data.

    PubMed

    Sriyudthsak, Kansuporn; Shiraishi, Fumihide; Hirai, Masami Yokota

    2016-01-01

    The high-throughput acquisition of metabolome data is greatly anticipated for the complete understanding of cellular metabolism in living organisms. A variety of analytical technologies have been developed to acquire large-scale metabolic profiles under different biological or environmental conditions. Time series data are useful for predicting the most likely metabolic pathways because they provide important information regarding the accumulation of metabolites, which implies causal relationships in the metabolic reaction network. Considerable effort has been undertaken to utilize these data for constructing a mathematical model merging system properties and quantitatively characterizing a whole metabolic system in toto. However, there are technical difficulties between benchmarking the provision and utilization of data. Although, hundreds of metabolites can be measured, which provide information on the metabolic reaction system, simultaneous measurement of thousands of metabolites is still challenging. In addition, it is nontrivial to logically predict the dynamic behaviors of unmeasurable metabolite concentrations without sufficient information on the metabolic reaction network. Yet, consolidating the advantages of advancements in both metabolomics and mathematical modeling remain to be accomplished. This review outlines the conceptual basis of and recent advances in technologies in both the research fields. It also highlights the potential for constructing a large-scale mathematical model by estimating model parameters from time series metabolome data in order to comprehensively understand metabolism at the systems level.

  13. Effect of Salivary Reaction Time on Flow Properties of Commercial Food Thickeners Used for Dysphagic Patients.

    PubMed

    Lee, Hwa-Young; Yoon, Seung-Ro; Yoo, Whachun; Yoo, Byoungseung

    2016-01-01

    The effect of human saliva on the flow properties of pudding-like thickened water prepared with commercial food thickeners was investigated, and their viscosity differences were also compared as a function of salivary reaction time (0-60 min after the addition of saliva). Food thickeners used in this study were starch-based (SB), gum-containing starch-based (GSB), and gumbased (GB) commercial thickeners marketed in Korea. GB showed no significant reduction in viscosity upon contact with human saliva during the salivary reaction. In contrast, SB almost completely lost its viscosity shortly after the addition of saliva, and GSB significantly reduced its viscosity after 20 min of reaction time but retained its viscosity. The results of this study indicate that GB can enhance the swallowing safety of dysphagic patients by retaining a stable viscosity level without the reduction of viscosity during consumption of thickened fluids, whereas SB may increase the possibility of aspiration owing to a rapid decrease of viscosity upon contact with human saliva.

  14. Effect of Salivary Reaction Time on Flow Properties of Commercial Food Thickeners Used for Dysphagic Patients

    PubMed Central

    Lee, Hwa-Young; Yoon, Seung-Ro; Yoo, Whachun

    2016-01-01

    The effect of human saliva on the flow properties of pudding-like thickened water prepared with commercial food thickeners was investigated, and their viscosity differences were also compared as a function of salivary reaction time (0-60 min after the addition of saliva). Food thickeners used in this study were starch-based (SB), gum-containing starch-based (GSB), and gumbased (GB) commercial thickeners marketed in Korea. GB showed no significant reduction in viscosity upon contact with human saliva during the salivary reaction. In contrast, SB almost completely lost its viscosity shortly after the addition of saliva, and GSB significantly reduced its viscosity after 20 min of reaction time but retained its viscosity. The results of this study indicate that GB can enhance the swallowing safety of dysphagic patients by retaining a stable viscosity level without the reduction of viscosity during consumption of thickened fluids, whereas SB may increase the possibility of aspiration owing to a rapid decrease of viscosity upon contact with human saliva. PMID:26839877

  15. Pattern formation on networks with reactions: A continuous-time random-walk approach

    NASA Astrophysics Data System (ADS)

    Angstmann, C. N.; Donnelly, I. C.; Henry, B. I.

    2013-03-01

    We derive the generalized master equation for reaction-diffusion on networks from an underlying stochastic process, the continuous time random walk (CTRW). The nontrivial incorporation of the reaction process into the CTRW is achieved by splitting the derivation into two stages. The reactions are treated as birth-death processes and the first stage of the derivation is at the single particle level, taking into account the death process, while the second stage considers an ensemble of these particles including the birth process. Using this model we have investigated different types of pattern formation across the vertices on a range of networks. Importantly, the CTRW defines the Laplacian operator on the network in a non-ad hoc manner and the pattern formation depends on the structure of this Laplacian. Here we focus attention on CTRWs with exponential waiting times for two cases: one in which the rate parameter is constant for all vertices and the other where the rate parameter is proportional to the vertex degree. This results in nonsymmetric and symmetric CTRW Laplacians, respectively. In the case of symmetric Laplacians, pattern formation follows from the Turing instability. However in nonsymmetric Laplacians, pattern formation may be possible with or without a Turing instability.

  16. Preconditioned time-difference methods for advection-diffusion-reaction equations

    SciTech Connect

    Aro, C.; Rodrigue, G.; Wolitzer, D.

    1994-12-31

    Explicit time differencing methods for solving differential equations are advantageous in that they are easy to implement on a computer and are intrinsically very parallel. The disadvantage of explicit methods is the severe restrictions placed on stepsize due to stability. Stability bounds for explicit time differencing methods on advection-diffusion-reaction problems are generally quite severe and implicit methods are used instead. The linear systems arising from these implicit methods are large and sparse so that iterative methods must be used to solve them. In this paper the authors develop a methodology for increasing the stability bounds of standard explicit finite differencing methods by combining explicit methods, implicit methods, and iterative methods in a novel way to generate new time-difference schemes, called preconditioned time-difference methods.

  17. Monitoring Acidophilic Microbes with Real-Time Polymerase Chain Reaction (PCR) Assays

    SciTech Connect

    Frank F. Roberto

    2008-08-01

    Many techniques that are used to characterize and monitor microbial populations associated with sulfide mineral bioleaching require the cultivation of the organisms on solid or liquid media. Chemolithotrophic species, such as Acidithiobacillus ferrooxidans and Leptospirillum ferrooxidans, or thermophilic chemolithotrophs, such as Acidianus brierleyi and Sulfolobus solfataricus can grow quite slowly, requiring weeks to complete efforts to identify and quantify these microbes associated with bioleach samples. Real-time PCR (polymerase chain reaction) assays in which DNA targets are amplified in the presence of fluorescent oligonucleotide primers, allowing the monitoring and quantification of the amplification reactions as they progress, provide a means of rapidly detecting the presence of microbial species of interest, and their relative abundance in a sample. This presentation will describe the design and use of such assays to monitor acidophilic microbes in the environment and in bioleaching operations. These assays provide results within 2-3 hours, and can detect less than 100 individual microbial cells.

  18. Effect of red bull energy drink on auditory reaction time and maximal voluntary contraction.

    PubMed

    Goel, Vartika; Manjunatha, S; Pai, Kirtana M

    2014-01-01

    The use of "Energy Drinks" (ED) is increasing in India. Students specially use these drinks to rejuvenate after strenuous exercises or as a stimulant during exam times. The most common ingredient in EDs is caffeine and a popular ED available and commonly used is Red Bull, containing 80 mg of caffeine in 250 ml bottle. The primary aim of this study was to investigate the effects of Red Bull energy drink on Auditory reaction time and Maximal voluntary contraction. A homogeneous group containing twenty medical students (10 males, 10 females) participated in a crossover study in which they were randomized to supplement with Red Bull (2 mg/kg body weight of caffeine) or isoenergetic isovolumetric noncaffeinated control drink (a combination of Appy Fizz, Cranberry juice and soda) separated by 7 days. Maximal voluntary contraction (MVC) was recorded as the highest of the 3 values of maximal isometric force generated from the dominant hand using hand grip dynamometer (Biopac systems). Auditory reaction time (ART) was the average of 10 values of the time interval between the click sound and response by pressing the push button using hand held switch (Biopac systems). The energy and control drinks after one hour of consumption significantly reduced the Auditory reaction time in males (ED 232 ± 59 Vs 204 ± 34 s and Control 223 ± 57 Vs 210 ± 51 s; p < 0.05) as well as in females (ED 227 ± 56 Vs 214 ± 48 s and Control 224 ± 45 Vs 215 ± 36 s; p < 0.05) but had no effect on MVC in either sex (males ED 381 ± 37 Vs 371 ± 36 and Control 375 ± 61 Vs 363 ± 36 Newton, females ED 227 ± 23 Vs 227 ± 32 and Control 234 ± 46 Vs 228 ± 37 Newton). When compared across the gender groups, there was no significant difference between males and females in the effects of any of the drinks on the ART but there was an overall significantly lower MVC in females compared to males. Both energy drink and the control drink significantly improve the reaction time but may not have any effect

  19. Effect of red bull energy drink on auditory reaction time and maximal voluntary contraction.

    PubMed

    Goel, Vartika; Manjunatha, S; Pai, Kirtana M

    2014-01-01

    The use of "Energy Drinks" (ED) is increasing in India. Students specially use these drinks to rejuvenate after strenuous exercises or as a stimulant during exam times. The most common ingredient in EDs is caffeine and a popular ED available and commonly used is Red Bull, containing 80 mg of caffeine in 250 ml bottle. The primary aim of this study was to investigate the effects of Red Bull energy drink on Auditory reaction time and Maximal voluntary contraction. A homogeneous group containing twenty medical students (10 males, 10 females) participated in a crossover study in which they were randomized to supplement with Red Bull (2 mg/kg body weight of caffeine) or isoenergetic isovolumetric noncaffeinated control drink (a combination of Appy Fizz, Cranberry juice and soda) separated by 7 days. Maximal voluntary contraction (MVC) was recorded as the highest of the 3 values of maximal isometric force generated from the dominant hand using hand grip dynamometer (Biopac systems). Auditory reaction time (ART) was the average of 10 values of the time interval between the click sound and response by pressing the push button using hand held switch (Biopac systems). The energy and control drinks after one hour of consumption significantly reduced the Auditory reaction time in males (ED 232 ± 59 Vs 204 ± 34 s and Control 223 ± 57 Vs 210 ± 51 s; p < 0.05) as well as in females (ED 227 ± 56 Vs 214 ± 48 s and Control 224 ± 45 Vs 215 ± 36 s; p < 0.05) but had no effect on MVC in either sex (males ED 381 ± 37 Vs 371 ± 36 and Control 375 ± 61 Vs 363 ± 36 Newton, females ED 227 ± 23 Vs 227 ± 32 and Control 234 ± 46 Vs 228 ± 37 Newton). When compared across the gender groups, there was no significant difference between males and females in the effects of any of the drinks on the ART but there was an overall significantly lower MVC in females compared to males. Both energy drink and the control drink significantly improve the reaction time but may not have any effect

  20. Secular Slowing of Auditory Simple Reaction Time in Sweden (1959-1985).

    PubMed

    Madison, Guy; Woodley Of Menie, Michael A; Sänger, Justus

    2016-01-01

    There are indications that simple reaction time might have slowed in Western populations, based on both cohort- and multi-study comparisons. A possible limitation of the latter method in particular is measurement error stemming from methods variance, which results from the fact that instruments and experimental conditions change over time and between studies. We therefore set out to measure the simple auditory reaction time (SRT) of 7,081 individuals (2,997 males and 4,084 females) born in Sweden 1959-1985 (subjects were aged between 27 and 54 years at time of measurement). Depending on age cut-offs and adjustment for aging related slowing of SRT, the data indicate that SRT has increased by between 3 and 16 ms in the 27 birth years covered in the present sample. This slowing is unlikely to be explained by attrition, which was evaluated by comparing the general intelligence × birth-year interactions and standard deviations for both male participants and dropouts, utilizing military conscript cognitive ability data. The present result is consistent with previous studies employing alternative methods, and may indicate the operation of several synergistic factors, such as recent micro-evolutionary trends favoring lower g in Sweden and the effects of industrially produced neurotoxic substances on peripheral nerve conduction velocity.

  1. Expression profiling by real-time quantitative polymerase chain reaction (RT-qPCR).

    PubMed

    Lech, Maciej; Anders, Hans-Joachim

    2014-01-01

    Real-time quantitative PCR is a variation of the standard PCR technique that is commonly used to quantify nucleic acid. However, in this technique the amount of amplified specific sequence can be quantified at each stage of the PCR cycle. If investigated sequence is present in large number of copies in particular sample, amplification product is detected already in earlier cycles; if the sequence is rare, amplification is observed in later cycles. Quantification of amplified product is acquired using fluorescent probes or fluorescent DNA-binding dyes. Accumulation of fluorescent signal can be measured by real-time PCR instruments during each of 35-45 cycwwles of the PCR reaction, which simplify the procedure by eliminating the visualization of the amplified products using gel electrophoresis. Real-time-PCR allows quantifying the amount of product already during the PCR reaction as soon as it is detectable. Correctly performed, this method may be used for precise gene expression analysis in life science, medicine, and diagnostics and has become the standard method of choice for the quantification of mRNA. However in the past few years it became obvious that real-time PCR is complex and variability of RNA templates, assay designs, inappropriate data normalization, and data interpretation may cause diverse analytical problems.

  2. Secular Slowing of Auditory Simple Reaction Time in Sweden (1959–1985)

    PubMed Central

    Madison, Guy; Woodley of Menie, Michael A.; Sänger, Justus

    2016-01-01

    There are indications that simple reaction time might have slowed in Western populations, based on both cohort- and multi-study comparisons. A possible limitation of the latter method in particular is measurement error stemming from methods variance, which results from the fact that instruments and experimental conditions change over time and between studies. We therefore set out to measure the simple auditory reaction time (SRT) of 7,081 individuals (2,997 males and 4,084 females) born in Sweden 1959–1985 (subjects were aged between 27 and 54 years at time of measurement). Depending on age cut-offs and adjustment for aging related slowing of SRT, the data indicate that SRT has increased by between 3 and 16 ms in the 27 birth years covered in the present sample. This slowing is unlikely to be explained by attrition, which was evaluated by comparing the general intelligence × birth-year interactions and standard deviations for both male participants and dropouts, utilizing military conscript cognitive ability data. The present result is consistent with previous studies employing alternative methods, and may indicate the operation of several synergistic factors, such as recent micro-evolutionary trends favoring lower g in Sweden and the effects of industrially produced neurotoxic substances on peripheral nerve conduction velocity. PMID:27588000

  3. Secular Slowing of Auditory Simple Reaction Time in Sweden (1959-1985).

    PubMed

    Madison, Guy; Woodley Of Menie, Michael A; Sänger, Justus

    2016-01-01

    There are indications that simple reaction time might have slowed in Western populations, based on both cohort- and multi-study comparisons. A possible limitation of the latter method in particular is measurement error stemming from methods variance, which results from the fact that instruments and experimental conditions change over time and between studies. We therefore set out to measure the simple auditory reaction time (SRT) of 7,081 individuals (2,997 males and 4,084 females) born in Sweden 1959-1985 (subjects were aged between 27 and 54 years at time of measurement). Depending on age cut-offs and adjustment for aging related slowing of SRT, the data indicate that SRT has increased by between 3 and 16 ms in the 27 birth years covered in the present sample. This slowing is unlikely to be explained by attrition, which was evaluated by comparing the general intelligence × birth-year interactions and standard deviations for both male participants and dropouts, utilizing military conscript cognitive ability data. The present result is consistent with previous studies employing alternative methods, and may indicate the operation of several synergistic factors, such as recent micro-evolutionary trends favoring lower g in Sweden and the effects of industrially produced neurotoxic substances on peripheral nerve conduction velocity. PMID:27588000

  4. The time scale of quasifission process in reactions with heavy ions

    NASA Astrophysics Data System (ADS)

    Knyazheva, G. N.; Itkis, I. M.; Kozulin, E. M.

    2014-05-01

    The study of mass-energy distributions of binary fragments obtained in the reactions of 36S, 48Ca, 58Fe and 64Ni ions with the 232Th, 238U, 244Pu and 248Cm at energies below and above the Coulomb barrier is presented. These data have been measured by two time-of-flight CORSET spectrometer. The mass resolution of the spectrometer for these measurements was about 3u. It allows to investigate the features of mass distributions with good accuracy. The properties of mass and TKE of QF fragments in dependence on interaction energy have been investigated and compared with characteristics of the fusion-fission process. To describe the quasifission mass distribution the simple method has been proposed. This method is based on the driving potential of the system and time dependent mass drift. This procedure allows to estimate QF time scale from the measured mass distributions. It has been found that the QF time exponentially decreases when the reaction Coulomb factor Z1Z2 increases.

  5. Defective sensorimotor integration in preparation for reaction time tasks in patients with multiple sclerosis.

    PubMed

    Cabib, Christopher; Llufriu, Sara; Casanova-Molla, Jordi; Saiz, Albert; Valls-Solé, Josep

    2015-03-01

    Slowness of voluntary movements in patients with multiple sclerosis (MS) may be due to various factors, including attentional and cognitive deficits, delays in motor conduction time, and impairment of specific central nervous system circuits. In 13 healthy volunteers and 20 mildly disabled, relapsing-remitting MS patients, we examined simple reaction time (SRT) tasks requiring sensorimotor integration in circuits involving the corpus callosum and the brain stem. A somatosensory stimulus was used as the imperative signal (IS), and subjects were requested to react with either the ipsilateral or the contralateral hand (uncrossed vs. crossed SRT). In 33% of trials, a startling auditory stimulus was presented together with the IS, and the percentage reaction time change with respect to baseline SRT trials was measured (StartReact effect). The difference between crossed and uncrossed SRT, which requires interhemispheric conduction, was significantly larger in patients than in healthy subjects (P = 0.021). The StartReact effect, which involves activation of brain stem motor pathways, was reduced significantly in patients with respect to healthy subjects (uncrossed trials: P = 0.015; crossed trials: P = 0.005). In patients, a barely significant correlation was found between SRT delay and conduction abnormalities in motor and sensory pathways (P = 0.02 and P = 0.04, respectively). The abnormalities found specifically in trials reflecting interhemispheric transfer of information, as well as the evidence for reduced subcortical motor preparation, indicate that a delay in reaction time execution in MS patients cannot be explained solely by conduction slowing in motor and sensory pathways but suggest, instead, defective sensorimotor integration mechanisms in at least the two circuits examined.

  6. Severe reactions to Cuprophan capillary dialyzers.

    PubMed

    Popli, S; Ing, T S; Daugirdas, J T; Kheirbek, A O; Viol, G W; Vilbar, R M; Gandhi, V C

    1982-08-01

    Five severe reactions occurred in four maintenance hemodialysis patients 1 to 5 minutes after initiating dialysis with Cuprophan capillary dialyzers. All reactions were life-threatening and one resulted in death. Inadequate rinsing of the dialyzers was probably the cause of the reactions. The severe reactions were managed by immediate discontinuation of dialysis and the institution of supportive treatment. Antianaphylactic measures were also attempted, but their therapeutic effectiveness remains to be determined. PMID:7181733

  7. Measuring Metacognition and Reaction Time: Further Findings on the Performances of General Education, Low-Achieving, and Institutionally Raised Students

    ERIC Educational Resources Information Center

    Al-Hilawani, Yasser A.; Abdullah, Ahmad A.

    2010-01-01

    The purpose of this study was to use the picture format to examine in depth the metacognitive performances and reaction time in general education, low-achieving, and institutionally raised students. Results revealed that institutionally raised students, unlike low-achieving students, took significantly the longest reaction time to finish the test…

  8. Corpus Callosum Size, Reaction Time Speed and Variability in Mild Cognitive Disorders and in a Normative Sample

    ERIC Educational Resources Information Center

    Anstey, Kaarin J.; Mack, Holly A.; Christensen, Helen; Li, Shu-Chen; Reglade-Meslin, Chantal; Maller, Jerome; Kumar, Rajeev; Dear, Keith; Easteal, Simon; Sachdev, Perminder

    2007-01-01

    Intra-individual variability in reaction time increases with age and with neurological disorders, but the neural correlates of this increased variability remain uncertain. We hypothesized that both faster mean reaction time (RT) and less intra-individual RT variability would be associated with larger corpus callosum (CC) size in older adults, and…

  9. A Reaction Time Advantage for Calculating Beliefs over Public Representations Signals Domain Specificity for "Theory of Mind"

    ERIC Educational Resources Information Center

    Cohen, Adam S.; German, Tamsin C.

    2010-01-01

    In a task where participants' overt task was to track the location of an object across a sequence of events, reaction times to unpredictable probes requiring an inference about a social agent's beliefs about the location of that object were obtained. Reaction times to false belief situations were faster than responses about the (false) contents of…

  10. Rare reaction channels in real-time time-dependent density functional theory: the test case of electron attachment

    NASA Astrophysics Data System (ADS)

    Lacombe, Lionel; Dinh, P. Huong Mai; Reinhard, Paul-Gerhard; Suraud, Eric; Sanche, Leon

    2015-08-01

    We present an extension of standard time-dependent density functional theory (TDDFT) to include the evaluation of rare reaction channels, taking as an example of application the theoretical modelling of electron attachment to molecules. The latter process is of great importance in radiation-induced damage of biological tissue for which dissociative electron attachment plays a decisive role. As the attachment probability is very low, it cannot be extracted from the TDDFT propagation whose mean field provides an average over various reaction channels. To extract rare events, we augment TDDFT by a perturbative treatment to account for the occasional jumps, namely electron capture in our test case. We apply the modelling to electron attachment to H2O, H3O+, and (H2O)2. Dynamical calculations have been done at low energy (3-16 eV). We explore, in particular, how core-excited states of the targets show up as resonances in the attachment probability. Contribution to the Topical Issue "COST Action Nano-IBCT: Nano-scale Processes Behind Ion-Beam Cancer Therapy", edited by Andrey Solov'yov, Nigel Mason, Gustavo García, Eugene Surdutovich.

  11. A reactant-coordinate-based time-dependent wave packet method for triatomic state-to-state reaction dynamics: application to the H + O2 reaction.

    PubMed

    Sun, Zhigang; Lin, Xin; Lee, Soo-Y; Zhang, Dong H

    2009-04-23

    A new time-dependent wavepacket method is developed to study the A + BC --> AB + C, AC + B reaction at the state-to-state level. The method only requires propagation of the wavepacket in reactant Jacobi coordinates by extracting S-matrix information on a dividing surface right before the absorption potential in the product region. It has particular advantages for reactions with deep wells and long-range attractive interactions in the product channels in which the wavepacket in the product channels can only be absorbed sufficiently far away from the interaction potential. Demonstration made on the benchmark H + H(2) reaction shows that the method is rather efficient in dealing with a direct reaction at high collision energy. The method is applied to study the very challenging H + O(2) (nu(0) = 0, j(0) = 0, 1) reaction, with state-to-state differential cross sections obtained for the first time for collision energies up to 1.1 eV. The calculations not only show the power and accuracy of the new approach in dealing with complex-forming reactions but also shed light on the dynamics of the H + O(2) reaction.

  12. Eye exercises enhance accuracy and letter recognition, but not reaction time, in a modified rapid serial visual presentation task.

    PubMed

    Di Noto, Paula; Uta, Sorin; DeSouza, Joseph F X

    2013-01-01

    Eye exercises have been prescribed to resolve a multitude of eye-related problems. However, studies on the efficacy of eye exercises are lacking, mainly due to the absence of simple assessment tools in the clinic. Because similar regions of the brain are responsible for eye movements and visual attention, we used a modified rapid serial visual presentation (RSVP) to assess any measurable effect of short-term eye exercise in improvements within these domains. In the present study, twenty subjects were equally divided into control and experimental groups, each of which performed a pre-training RSVP assessment where target letters, to which subjects were asked to respond to by pressing a spacebar, were serially and rapidly presented. Response time to target letters, accuracy of correctly responding to target letters, and correct identification of target letters in each of 12 sessions was measured. The experimental group then performed active eye exercises, while the control group performed a task that minimized eye movements for 18.5 minutes. A final post-training RSVP assessment was performed by both groups and response time, accuracy, and letter identification were compared between and within subject groups both pre- and post-training. Subjects who performed eye exercises were more accurate in responding to target letters separated by one distractor and in letter identification in the post-training RSVP assessment, while latency of responses were unchanged between and within groups. This suggests that eye exercises may prove useful in enhancing cognitive performance on tasks related to attention and memory over a very brief course of training, and RSVP may be a useful measure of this efficacy. Further research is needed on eye exercises to determine whether they are an effective treatment for patients with cognitive and eye-related disorders.

  13. Horizontal geometrical reaction time model for two-beam nacelle LiDARs

    NASA Astrophysics Data System (ADS)

    Beuth, Thorsten; Fox, Maik; Stork, Wilhelm

    2015-06-01

    Wind energy is one of the leading sustainable energies. To attract further private and state investment in this technology, a broad scaled drop of the cost of energy has to be enforced. There is a trend towards using Laser Doppler Velocimetry LiDAR systems for enhancing power output and minimizing downtimes, fatigue and extreme forces. Since most used LiDARs are horizontally setup on a nacelle and work with two beams, it is important to understand the geometrical configuration which is crucial to estimate reaction times for the actuators to compensate wind gusts. In the beginning of this article, the basic operating modes of wind turbines are explained and the literature on wind behavior is analyzed to derive specific wind speed and wind angle conditions in relation to the yaw angle of the hub. A short introduction to the requirements for the reconstruction of the wind vector length and wind angle leads to the problem of wind shear detection of angled but horizontal homogeneous wind fronts due to the spatial separation of the measuring points. A distance is defined in which the wind shear of such homogeneous wind fronts is not present which is used as a base to estimate further distance calculations. The reaction time of the controller and the actuators are having a negative effect on the effective overall reaction time for wind regulation as well. In the end, exemplary calculations estimate benefits and disadvantages of system parameters for wind gust regulating LiDARs for a wind turbine of typical size. An outlook shows possible future improvements concerning the vertical wind behavior.

  14. Effect of iron deficiency anemia on audiovisual reaction time in adolescent girls.

    PubMed

    Kahlon, Namrata; Gandhi, Asha; Mondal, Sunita; Narayan, Shashi

    2011-01-01

    Adolescent girls are at high risk of developing iron deficiency because of increased iron demands during puberty, menstrual losses, and limited dietary iron intake. This study was carried out to demonstrate the effects of Iron Deficiency Anemia on Audiovisual reaction time in adolescent girls. Adolescent girls between 17-19 years of age with similar socioeconomic background were recruited from college of nursing for the study. They were all screened and categorized into two groups depending on their haemoglobin status. Students having Hb > 12 gm/dl formed the control group i.e. Group I (n=30). All students having Hb < 12 gm/dl and S. Ferritin < 12 microg/dl formed group II i.e. iron deficient anemic (IDA) group. The following haematological parameters were studied Hemoglobin (Hb), MCV, MCH, MCHC (using Sysmex kx-21 Autoanalyser), Serum.Iron, TIBC (Spectrophotometry), Serum.Ferritin (ELISA). Auditory and Visual reaction time were measured by reaction time instrument supplied by Medicaid system, chandigarh. The mean Hb levels in Group I was 12.93 +/- 0.86 and Group II was 10.08 +/- 0.51 (P<0.001). The MCV, MCH, MCHC, S. Iron, S. Ferritin was also significantly less in group II as compared to group I (P<0.001). TIBC was significantly more in group II as compared to group I (P<0.001). Results showed that both ART and VRT were significantly increased (P<0.001) in iron deficient adolescents suggesting a deterioration in sensorimotor performance in anemics.

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

    PubMed Central

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

    2014-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2004-03-01

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

  17. Prediction of motor imagery based brain computer interface performance using a reaction time test.

    PubMed

    Darvishi, Sam; Abbott, Derek; Baumert, Mathias

    2015-08-01

    Brain computer interfaces (BCIs) enable human brains to interact directly with machines. Motor imagery based BCI (MI-BCI) encodes the motor intentions of human agents and provides feedback accordingly. However, 15-30% of people are not able to perform vivid motor imagery. To save time and monetary resources, a number of predictors have been proposed to screen for users with low BCI aptitude. While the proposed predictors provide some level of correlation with MI-BCI performance, simple, objective and accurate predictors are currently not available. Thus, in this study we have examined the utility of a simple reaction time (SRT) test for predicting MI-BCI performance. We enrolled 10 subjects and measured their motor imagery performance with either visual or proprioceptive feedback. Their reaction time was also measured using a SRT test. The results show a significant negative correlation (r ≈ -0.67) between SRT and MI-BCI performance. Therefore SRT may be used as a simple and reliable predictor of MI-BCI performance. PMID:26736893

  18. The benefits of errorless learning for serial reaction time performance in Alzheimer's disease.

    PubMed

    Schmitz, Xavier; Bier, Nathalie; Joubert, Sven; Lejeune, Caroline; Salmon, Eric; Rouleau, Isabelle; Meulemans, Thierry

    2014-01-01

    Identifying the conditions favoring new procedural skill learning in Alzheimer's disease (AD) could be important for patients' autonomy. It has been suggested that error elimination is beneficial during skill learning, but no study has explored the advantage of this method in sequential learning situations. In this study, we examined the acquisition of a 6-element perceptual-motor sequence by AD patients and healthy older adults (control group). We compared the impact of two preliminary sequence learning conditions (Errorless versus Errorful) on Serial Reaction Time performance at two different points in the learning process. A significant difference in reaction times for the learned sequence and a new sequence was observed in both conditions in healthy older participants; in AD patients, the difference was significant only in the errorless condition. The learning effect was greater in the errorless than the errorful condition in both groups. However, while the errorless advantage was found at two different times in the learning process in the AD group, in the control group this advantage was observed only at the halfway point. These results support the hypothesis that errorless learning allows for faster automation of a procedure than errorful learning in both AD and healthy older subjects.

  19. A mathematical model of saccadic reaction time as a function of the fixation point brightness gain.

    PubMed

    Diaz-Tula, Antonio; Morimoto, Carlos H; Ranvaud, Ronald D

    2015-08-01

    The gap effect refers to a reduction in saccadic reaction time (SRT) to an eccentric target, when the fixation point is removed before the target onset. Though it is known that the gap effect peaks when the fixation point is offset about 200 ms before the onset of the eccentric target, it is unknown how this effect is modulated by stimulus variations. In this paper, we propose and investigate a model of saccadic reaction time as a function of the fixation point brightness gain. The brightness gain is defined as the ratio of the final and initial intensities of the stimulus. We have conducted a typical gap effect experiment with 15 participants, where the brightness of the fixation point was manipulated under four conditions and two gap intervals, at the same time and 200 ms before the onset of the eccentric target. The conditions included removing the fixation point (offset), leaving it with constant brightness (overlap), reducing, and increasing its brightness (lower and higher brightness conditions). Experimental data showed a significant gap effect in the offset and lower brightness conditions when compared to the overlap condition. On the other hand, the SRT was significantly longer for the higher brightness condition than the SRT for the overlap condition. Linear regression analysis using ten values of brightness gain shows that our model fits the data well for the 0- and 200-ms gap, with a coefficient of determination of .89 and .94, respectively. PMID:25962456

  20. Integrating impairments in reaction time and executive function using a diffusion model framework

    PubMed Central

    Karalunas, Sarah L.; Huang-Pollock, Cynthia L.

    2013-01-01

    Using Ratcliff’s diffusion model and ex-Gaussian decomposition, we directly evaluate the role individual differences in reaction time (RT) distribution components play in the prediction of inhibitory control and working memory (WM) capacity in children with and without ADHD. Children with (n=92, x̄ age= 10.2 years, 67% male) and without ADHD (n=62, x̄ age=10.6 years, 46% male) completed four tasks of WM and a stop signal reaction time (SSRT) task. Children with ADHD had smaller WM capacities and less efficient inhibitory control. Diffusion model analyses revealed that children with ADHD had slower drift rates (v) and faster non-decision times (Ter), but there were no group differences in boundary separations (a). Similarly, using an ex-Gaussian approach, children with ADHD had larger τ values than non-ADHD controls, but did not differ in µ or σ distribution components. Drift rate mediated the association between ADHD status and performance on both inhibitory control and WM capacity. τ also mediated the ADHD-executive function impairment associations; however, models were a poorer fit to the data. Impaired performance on RT and executive functioning tasks has long been associated with childhood ADHD. Both are believed to be important cognitive mechanisms to the disorder. We demonstrate here that drift rate, or the speed at which information accumulates towards a decision, is able to explain both. PMID:23334775

  1. Barriers to reaction front propagation in a spatially random, time-independent flow

    NASA Astrophysics Data System (ADS)

    Bargteil, Dylan; Solomon, Tom; Mahoney, John; Mitchell, Kevin

    2011-11-01

    We present experimental studies of barriers, called burning invariant manifolds (BIMs), to front propagation in a spatially random, time-independent flow. We generate the flow with a magnetohydrodynamic technique that uses a DC current and a disordered pattern of permanent magnets. The velocity field is determined from this flow using particle tracking velocimetry, and reaction fronts are produced using the Ferroin-catalyzed Belousov-Zhabotinsky (BZ) chemical reaction. We use the experimental velocity field and a three-dimensional set of ODEs to predict from theory the location and orientation of BIMs. These predicted BIMs are found to match up well with the propagation barriers observed experimentally in the same flow using the BZ reaction. We explore the nature of BIMs as one-sided barriers, in contrast to invariant manifolds that act as barriers for passive transport in all directions. We also explore the role of projection singularities in the theory and how these singularities affect front behavior. Supported by NSF Grants DMR-0703635, DMR-1004744, PHY-0552790 and PHY-0748828.

  2. Emotions over time: synchronicity and development of subjective, physiological, and facial affective reactions to music.

    PubMed

    Grewe, Oliver; Nagel, Frederik; Kopiez, Reinhard; Altenmüller, Eckart

    2007-11-01

    Most people are able to identify basic emotions expressed in music and experience affective reactions to music. But does music generally induce emotion? Does it elicit subjective feelings, physiological arousal, and motor reactions reliably in different individuals? In this interdisciplinary study, measurement of skin conductance, facial muscle activity, and self-monitoring were synchronized with musical stimuli. A group of 38 participants listened to classical, rock, and pop music and reported their feelings in a two-dimensional emotion space during listening. The first entrance of a solo voice or choir and the beginning of new sections were found to elicit interindividual changes in subjective feelings and physiological arousal. Quincy Jones' "Bossa Nova" motivated movement and laughing in more than half of the participants. Bodily reactions such as "goose bumps" and "shivers" could be stimulated by the "Tuba Mirum" from Mozart's Requiem in 7 of 38 participants. In addition, the authors repeated the experiment seven times with one participant to examine intraindividual stability of effects. This exploratory combination of approaches throws a new light on the astonishing complexity of affective music listening.

  3. Monitoring Enzymatic Reactions in Real Time Using Venturi Easy Ambient Sonic-Spray Ionization Mass Spectrometry

    PubMed Central

    2016-01-01

    We developed a technique to monitor spatially confined surface reactions with mass spectrometry under ambient conditions, without the need for voltage or organic solvents. Fused-silica capillaries immersed in an aqueous solution, positioned in close proximity to each other and the functionalized surface, created a laminar flow junction with a resulting reaction volume of ∼5 pL. The setup was operated with a syringe pump, delivering reagents to the surface through a fused-silica capillary. The other fused-silica capillary was connected to a Venturi easy ambient sonic-spray ionization source, sampling the resulting analytes at a slightly higher flow rate compared to the feeding capillary. The combined effects of the inflow and outflow maintains a chemical microenvironment, where the rate of advective transport overcomes diffusion. We show proof-of-concept where acetylcholinesterase was immobilized on an organosiloxane polymer through electrostatic interactions. The hydrolysis of acetylcholine by acetylcholinesterase into choline was monitored in real-time for a range of acetylcholine concentrations, fused-silica capillary geometries, and operating flow rates. Higher reaction rates and conversion yields were observed with increasing acetylcholine concentrations, as would be expected. PMID:27249533

  4. Monitoring Enzymatic Reactions in Real Time Using Venturi Easy Ambient Sonic-Spray Ionization Mass Spectrometry.

    PubMed

    Jansson, Erik T; Dulay, Maria T; Zare, Richard N

    2016-06-21

    We developed a technique to monitor spatially confined surface reactions with mass spectrometry under ambient conditions, without the need for voltage or organic solvents. Fused-silica capillaries immersed in an aqueous solution, positioned in close proximity to each other and the functionalized surface, created a laminar flow junction with a resulting reaction volume of ∼5 pL. The setup was operated with a syringe pump, delivering reagents to the surface through a fused-silica capillary. The other fused-silica capillary was connected to a Venturi easy ambient sonic-spray ionization source, sampling the resulting analytes at a slightly higher flow rate compared to the feeding capillary. The combined effects of the inflow and outflow maintains a chemical microenvironment, where the rate of advective transport overcomes diffusion. We show proof-of-concept where acetylcholinesterase was immobilized on an organosiloxane polymer through electrostatic interactions. The hydrolysis of acetylcholine by acetylcholinesterase into choline was monitored in real-time for a range of acetylcholine concentrations, fused-silica capillary geometries, and operating flow rates. Higher reaction rates and conversion yields were observed with increasing acetylcholine concentrations, as would be expected. PMID:27249533

  5. Threshold dynamics of a time periodic reaction-diffusion epidemic model with latent period

    NASA Astrophysics Data System (ADS)

    Zhang, Liang; Wang, Zhi-Cheng; Zhao, Xiao-Qiang

    2015-05-01

    In this paper, we first propose a time-periodic reaction-diffusion epidemic model which incorporates simple demographic structure and the latent period of infectious disease. Then we introduce the basic reproduction number R0 for this model and prove that the sign of R0 - 1 determines the local stability of the disease-free periodic solution. By using the comparison arguments and persistence theory, we further show that the disease-free periodic solution is globally attractive if R0 < 1, while there is an endemic periodic solution and the disease is uniformly persistent if R0 > 1.

  6. The Visual and Auditory Reaction Time of Adolescents with Respect to Their Academic Achievements

    ERIC Educational Resources Information Center

    Taskin, Cengiz

    2016-01-01

    The aim of this study was to examine in visual and auditory reaction time of adolescents with respect to their academic achievement level. Five hundred adolescent children from the Turkey, (age=15.24±0.78 years; height=168.80±4.89 cm; weight=65.24±4.30 kg) for two hundred fifty male and (age=15.28±0.74; height=160.40±5.77 cm; weight=55.32±4.13 kg)…

  7. Factors Affecting the Timing of Signal Detection of Adverse Drug Reactions.

    PubMed

    Hashiguchi, Masayuki; Imai, Shungo; Uehara, Keiko; Maruyama, Junya; Shimizu, Mikiko; Mochizuki, Mayumi

    2015-01-01

    We investigated factors affecting the timing of signal detection by comparing variations in reporting time of known and unknown ADRs after initial drug release in the USA. Data on adverse event reactions (AERs) submitted to U.S. FDA was used. Six ADRs associated with 6 drugs (rosuvastatin, aripiprazole, teriparatide, telithromycin, exenatide, varenicline) were investigated: Changes in the proportional reporting ratio, reporting odds ratio, and information component as indexes of signal detection were followed every 3 months after each drugs release, and the time for detection of signals was investigated. The time for the detection of signal to be detected after drug release in the USA was 2-10 months for known ADRs and 19-44 months for unknown ones. The median lag time for known and unknown ADRs was 99.0-122.5 days and 185.5-306.0 days, respectively. When the FDA released advisory information on rare but potentially serious health risks of an unknown ADR, the time lag to report from the onset of ADRs to the FDA was shorter. This study suggested that one factor affecting signal detection time is whether an ADR was known or unknown at release. PMID:26641634

  8. [Methods Used for Monitoring Cure Reactions in Real-time in an Autoclave

    NASA Technical Reports Server (NTRS)

    Cooper, John B.; Wise, Kent L.; Jensen, Brian J. (Technical Monitor)

    2000-01-01

    The goal of the research was to investigate methods for monitoring cure reactions in real-time in an autoclave. This is of particular importance to NASA Langley Research Center because polyimides were proposed for use in the High Speed Civil Transport (HSCT) program. Understanding the cure chemistry behind the polyimides would allow for intelligent processing of the composites made from their use. This work has led to two publications in peer-reviewed journals and a patent. The journal articles are listed as Appendix A which is on the instrument design of the research and Appendix B which is on the cure chemistry. Also, a patent has been awarded for the instrumental design developed under this grant which is given as Appendix C. There has been a significant amount of research directed at developing methods for monitoring cure reactions in real-time within the autoclave. The various research efforts can be categorized as methods providing either direct chemical bonding information or methods that provide indirect chemical bonding information. Methods falling into the latter category are fluorescence, dielectric loss, ultrasonic and similar type methods. Correlation of such measurements with the underlying chemistry is often quite difficult since these techniques do not allow monitoring of the curing chemistry which is ultimately responsible for material properties. Direct methods such as vibrational spectroscopy, however, can often be easily correlated with the underlying chemistry of a reaction. Such methods include Raman spectroscopy, mid-IR absorbance, and near-IR absorbance. With the recent advances in fiber-optics, these spectroscopic techniques can be applied to remote on-line monitoring.

  9. Opposite effects of sleep deprivation on the continuous reaction times in patients with liver cirrhosis and normal persons.

    PubMed

    Lauridsen, Mette Munk; Frøjk, Jesper; de Muckadell, Ove B Schaffalitzky; Vilstrup, Hendrik

    2014-09-01

    The continuous reaction times (CRT) method describes arousal functions. Reaction time instability in a patient with liver disease indicates covert hepatic encephalopathy (cHE). The effects of sleep deprivation are unknown although cirrhosis patients frequently suffer from sleep disorders. The aim of this study was to determine if sleep deprivation influences the CRT test. Eighteen cirrhosis patients and 27 healthy persons were tested when rested and after one night's sleep deprivation. The patients filled out validated sleep quality questionnaires. Seven patients (38%) had unstable reaction times (a CRTindex < 1.9) compatible with cHE. In these patients, the wakefulness improved or normalized their reaction speed and CRTindex (p = 0.01). There was no change in the other patients' reaction speed or stability. Seven patients (38%) reported poor sleep that was not related to their CRT tests before or after the sleep deprivation. In the healthy participants, the sleep deprivation slowed their reaction times by 11% (p < 0.0001) and in 7 persons (25%) destabilized them. The acute sleep deprivation normalized or improved the reaction time stability of the patients with a CRTindex below 1.9 and had no effect in the patients with a CRTindex above 1.9. There was no relation between reported sleep quality and reaction time results. Thus, in cirrhosis patients, sleep disturbances do not lead to 'falsely' slowed and unstable reaction times. In contrast, the acute sleep deprivation slowed and destabilized the reaction times of the healthy participants. This may have negative consequences for decision-making.

  10. Monitoring transcranial direct current stimulation induced changes in cortical excitability during the serial reaction time task.

    PubMed

    Ambrus, Géza Gergely; Chaieb, Leila; Stilling, Roman; Rothkegel, Holger; Antal, Andrea; Paulus, Walter

    2016-03-11

    The measurement of the motor evoked potential (MEP) amplitudes using single pulse transcranial magnetic stimulation (TMS) is a common method to observe changes in motor cortical excitability. The level of cortical excitability has been shown to change during motor learning. Conversely, motor learning can be improved by using anodal transcranial direct current stimulation (tDCS). In the present study, we aimed to monitor cortical excitability changes during an implicit motor learning paradigm, a version of the serial reaction time task (SRTT). Responses from the first dorsal interosseous (FDI) and forearm flexor (FLEX) muscles were recorded before, during and after the performance of the SRTT. Online measurements were combined with anodal, cathodal or sham tDCS for the duration of the SRTT. Negative correlations between the amplitude of online FDI MEPs and SRTT reaction times (RTs) were observed across the learning blocks in the cathodal condition (higher average MEP amplitudes associated with lower RTs) but no significant differences in the anodal and sham conditions. tDCS did not have an impact on SRTT performance, as would be predicted based on previous studies. The offline before-after SRTT MEP amplitudes showed an increase after anodal and a tendency to decrease after cathodal stimulation, but these changes were not significant. The combination of different interventions during tDCS might result in reduced efficacy of the stimulation that in future studies need further attention.

  11. Inhibitory processes relate differently to balance/reaction time dual tasks in young and older adults

    PubMed Central

    Mendelson, David N.; Redfern, Mark S.; Nebes, Robert D.; Jennings, J. Richard

    2016-01-01

    Inhibitory processes have been suggested to be involved in maintaining balance in older adults, specifically in the integration of sensory information. This study investigated the association between inhibition and the ability to shift attention between auditory and visual modalities during a balance challenge. Young (21–35 yrs; n=24) and older (70–85 yrs; n=22) healthy subjects completed tasks assessing perceptual inhibition and motor inhibition. Subjects then performed dual-task paradigms pairing auditory and visual choice reaction time tasks with different postural conditions. Sensory channel switch cost was quantified as the difference between visual and auditory reaction times. Results showed that better perceptual and motor inhibition capabilities were associated with less sensory switch cost in the old (perceptual inhibition: r=0.51; motor inhibition: r=0.48). In the young, neither perceptual nor motor inhibition was associated with sensory switch cost. Inhibitory skills appear particularly important in the elderly for processing events from multiple sensory channels while maintaining balance. PMID:19526388

  12. Multiple deficits in ADHD: executive dysfunction, delay aversion, reaction time variability, and emotional deficits

    PubMed Central

    Sjöwall, Douglas; Roth, Linda; Lindqvist, Sofia; Thorell, Lisa B

    2013-01-01

    Background The notion that ADHD constitutes a heterogeneous disorder is well accepted. However, this study contributes with new important knowledge by examining independent effects of a large range of neuropsychological deficits. In addition, the study investigated whether deficits in emotional functioning constitute a dissociable component of ADHD. Method The study included children with ADHD (n = 102; 7–13 years) and a control sample individually matched with regard to age and gender. The administered tasks were designed to tap into three different neuropsychological domains: executive functions (i.e., working memory, inhibition, and shifting), delay aversion, and reaction time variability. Parent ratings of emotion regulation and a test of emotion recognition were also included. Results Children with ADHD differed significantly from controls on all measures, except for delay aversion and recognition of disgust. No main effects of gender or interaction effects of gender and group were found. More importantly, executive functioning, reaction time variability, and emotional functioning all contributed independently to distinguishing between children with ADHD and controls. Conclusions The current study supports the view of ADHD as a heterogeneous disorder related to multiple neuropsychological deficits. In addition, emotional functioning appears to be an area of importance for ADHD that needs to be incorporated into future theoretical models. PMID:23061803

  13. Real-time and in situ monitoring of mechanochemical milling reactions.

    PubMed

    Friščić, Tomislav; Halasz, Ivan; Beldon, Patrick J; Belenguer, Ana M; Adams, Frank; Kimber, Simon A J; Honkimäki, Veijo; Dinnebier, Robert E

    2013-01-01

    Chemical and structural transformations have long been carried out by milling. Such mechanochemical steps are now ubiquitous in a number of industries (such as the pharmaceutical, chemical and metallurgical industries), and are emerging as excellent environmentally friendly alternatives to solution-based syntheses. However, mechanochemical transformations are typically difficult to monitor in real time, which leaves a large gap in the mechanistic understanding required for their development. We now report the real-time study of mechanochemical transformations in a ball mill by means of in situ diffraction of high-energy synchrotron X-rays. Focusing on the mechanosynthesis of metal-organic frameworks, we have directly monitored reaction profiles, the formation of intermediates, and interconversions of framework topologies. Our results reveal that mechanochemistry is highly dynamic, with reaction rates comparable to or greater than those in solution. The technique also enabled us to probe directly how catalytic additives recently introduced in the mechanosynthesis of metal-organic frameworks, such as organic liquids or ionic species, change the reactivity pathways and kinetics.

  14. Analysis of the HindIII-catalyzed reaction by time-resolved crystallography

    PubMed Central

    Kawamura, Takashi; Kobayashi, Tomoki; Watanabe, Nobuhisa

    2015-01-01

    In order to investigate the mechanism of the reaction catalyzed by HindIII, structures of HindIII–DNA complexes with varying durations of soaking time in cryoprotectant buffer containing manganese ions were determined by the freeze-trap method. In the crystal structures of the complexes obtained after soaking for a longer duration, two manganese ions, indicated by relatively higher electron density, are clearly observed at the two metal ion-binding sites in the active site of HindIII. The increase in the electron density of the two metal-ion peaks followed distinct pathways with increasing soaking times, suggesting variation in the binding rate constant for the two metal sites. DNA cleavage is observed when the second manganese ion appears, suggesting that HindIII uses the two-metal-ion mechanism, or alternatively that its reactivity is enhanced by the binding of the second metal ion. In addition, conformational change in a loop near the active site accompanies the catalytic reaction. PMID:25664735

  15. Oculomotor, Vestibular, and Reaction Time Tests in Mild Traumatic Brain Injury

    PubMed Central

    Szczupak, Mikhaylo; Snapp, Hillary; Crawford, James; Murphy, Sara; Marshall, Kathryn; Pelusso, Constanza; Knowles, Sean; Kiderman, Alex

    2016-01-01

    Objective Mild traumatic brain injury is a major public health issue and is a particular concern in sports. One of the most difficult issues with respect to mild traumatic brain injury involves the diagnosis of the disorder. Typically, diagnosis is made by a constellation of physical exam findings. However, in order to best manage mild traumatic brain injury, it is critically important to develop objective tests that substantiate the diagnosis. With objective tests the disorder can be better characterized, more accurately diagnosed, and studied more effectively. In addition, prevention and treatments can be applied where necessary. Methods Two cohorts each of fifty subjects with mild traumatic brain injury and one hundred controls were evaluated with a battery of oculomotor, vestibular and reaction time related tests applied to a population of individuals with mild traumatic brain injury as compared to controls. Results We demonstrated pattern differences between the two groups and showed how three of these tests yield an 89% sensitivity and 95% specificity for confirming a current diagnosis of mild traumatic brain injury. Interpretation These results help better characterize the oculomotor, vestibular, and reaction time differences between those the mild traumatic brain injury and non-affected individuals. This characterization will allow for the development of more effective point of care neurologic diagnostic techniques and allow for more targeted treatment which may allow for quicker return to normal activity. PMID:27654131

  16. Slowed central processing in simple and go/no-go reaction time tasks in Parkinson's disease.

    PubMed

    Cooper, J A; Sagar, H J; Tidswell, P; Jordan, N

    1994-06-01

    Studies of cognition and motor control have independently suggested that patients with Parkinson's disease show deficits in both attentional control and the preprogramming of movement. However, few studies have examined directly the involvement of cognitive processes in the origin of their slowed response. We examined the performance of 100 Parkinson's disease patients on simple reaction time (SRT) and a series of go/no-go cross-modality choice reaction time (CRT) tasks, in which motor response was constant; correct positive responses required attention to a progressively increasing number of dimensions of visual and auditory stimuli. The results showed that Parkinson's disease patients became increasingly impaired in response speed as choice complexity increased. Slowed response speed in Parkinson's disease involved two factors: (i) a 'perceptuomotor' factor which was constant across conditions and independent of choice complexity. Depression affected this factor selectively and independently of confounding associations with impoverished motor control; (ii) a 'cognitive-analytical' factor, which played an increasingly important role as complexity of choice increased. The characteristics of the relationship between response latency and cognitive complexity indicate that the deficit was due to a constant proportional slowing in cognitive speed across all SRT and CRT conditions. A cognitive deficit affecting the monitoring of stimulus-response compatibility may contribute to delayed response in Parkinson's disease. This cognitive-analytical deficit is present in early, untreated cases and, in contrast to perceptuomotor processes, is weakly related to depression. PMID:8032862

  17. Effects of angular acceleration on man - Choice reaction time using visual and rotary motion information

    NASA Technical Reports Server (NTRS)

    Clark, B.; Stewart, J. D.

    1974-01-01

    This experiment was concerned with the effects of rotary acceleration on choice reaction time (RTc) to the motion of a luminous line on a cathode-ray tube. Specifically, it compared the (RTc) to rotary acceleration alone, visual acceleration alone, and simultaneous, double stimulation by both rotary and visual acceleration. Thirteen airline pilots were rotated about an earth-vertical axis in a precision rotation device while they observed a vertical line. The stimuli were 7 rotary and visual accelerations which were matched for rise time. The pilot responded as quickly as possible by displacing a vertical controller to the right or left. The results showed a decreasing (RTc) with increasing acceleration for all conditions, while the (RTc) to rotary motion alone was substantially longer than for all other conditions. The (RTc) to the double stimulation was significantly longer than that for visual acceleration alone.

  18. Effects of age, intelligence and executive control function on saccadic reaction time in persons with intellectual disabilities.

    PubMed

    Haishi, Koichi; Okuzumi, Hideyuki; Kokubun, Mitsuru

    2011-01-01

    The current research aimed to clarify the influence of age, intelligence and executive control function on the central tendency and intraindividual variability of saccadic reaction time in persons with intellectual disabilities. Participants were 44 persons with intellectual disabilities aged between 13 and 57 years whose IQs were between 14 and 70. Executive control function was evaluated by a test of sustained simple motor action. To elicit saccades, a predictive visually guided saccade paradigm was used. Intelligence and executive control function were significantly associated with saccadic reaction time. The central tendency of saccadic reaction time was negatively correlated with intelligence. The more serious the degree of executive control dysfunction was, the larger the intraindividual variability of saccadic reaction time. It is thought that intelligence and executive control function have relatively independent influences on saccadic reaction time. However, there is a possibility that the increase of intraindividual variability in saccadic reaction time due to the problem of executive control function extends the central tendency of saccadic reaction time. PMID:21742468

  19. Effects of a pretarget distractor on saccade reaction times across space and time in monkeys and humans.

    PubMed

    Khan, Aarlenne Z; Munoz, Douglas P; Takahashi, Naomi; Blohm, Gunnar; McPeek, Robert M

    2016-05-01

    Previous studies have shown that the influence of a behaviorally irrelevant distractor on saccade reaction times (SRTs) varies depending on the temporal and spatial relationship between the distractor and the saccade target. We measured distractor influence on SRTs to a subsequently presented target, varying the spatial location and the timing between the distractor and the target. The distractor appeared at one of four equally eccentric locations, followed by a target (either 50 ms or 200 ms after) at one of 136 different locations encompassing an area of 20° square. We extensively tested two humans and two monkeys on this task to determine interspecies similarities and differences, since monkey neurophysiology is often used to interpret human behavioral findings. Results were similar across species; for the short interval (50 ms), SRTs were shortest to a target presented close to or at the distractor location and increased primarily as a function of the distance from the distractor. There was also an effect of distractor-target direction and visual field. For the long interval (200 ms) the results were inverted; SRTs were longest for short distances between the distractor and target and decreased as a function of distance from distractor. Both SRT patterns were well captured by a two-dimensional dynamic field model with short-distance excitation and long-distance inhibition, based upon known functional connectivity found in the superior colliculus that includes wide-spread excitation and inhibition. Based on these findings, we posit that the different time-dependent patterns of distractor-related SRTs can emerge from the same underlying neuronal mechanisms common to both species.

  20. The Effect of Mechanical Vibration Stimulation of Perception Subthreshold on the Muscle Force and Muscle Reaction Time of Lower Leg.

    PubMed

    Kim, Huigyun; Kwak, Kiyoung; Kim, Dongwook

    2016-01-01

    The objective of this study is to investigate the effect of mechanical vibration stimulation on the muscle force and muscle reaction time of lower leg according to perception threshold and vibration frequency. A vibration stimulation with perception threshold intensity was applied on the Achilles tendon and tibialis anterior tendon. EMG measurement and analysis system were used to analyze the change of muscle force and muscle reaction time according to perception threshold and vibration frequency. A root-mean-square (RMS) value was extracted using analysis software and Maximum Voluntary Contraction (MVC) and Premotor Time (PMT) were analyzed. The measurement results showed that perception threshold was different from application sites of vibration frequency. Also, the muscle force and muscle reaction time showed difference according to the presence of vibration, frequency, and intensity. This result means that the vibration stimulation causes the change on the muscle force and muscle reaction time and affects the muscles of lower leg by the characteristics of vibration stimulation.

  1. Theory and simulation of the time-dependent rate coefficients of diffusion-influenced reactions.

    PubMed Central

    Zhou, H X; Szabo, A

    1996-01-01

    A general formalism is developed for calculating the time-dependent rate coefficient k(t) of an irreversible diffusion-influenced reaction. This formalism allows one to treat most factors that affect k(t), including rotational Brownian motion and conformational gating of reactant molecules and orientation constraint for product formation. At long times k(t) is shown to have the asymptotic expansion k(infinity)[1 + k(infinity) (pie Dt)-1/2 /4 pie D + ...], where D is the relative translational diffusion constant. An approximate analytical method for calculating k(t) is presented. This is based on the approximation that the probability density of the reactant pair in the reactive region keeps the equilibrium distribution but with a decreasing amplitude. The rate coefficient then is determined by the Green function in the absence of chemical reaction. Within the framework of this approximation, two general relations are obtained. The first relation allows the rate coefficient for an arbitrary amplitude of the reactivity to be found if the rate coefficient for one amplitude of the reactivity is known. The second relation allows the rate coefficient in the presence of conformational gating to be found from that in the absence of conformational gating. The ratio k(t)/k(0) is shown to be the survival probability of the reactant pair at time t starting from an initial distribution that is localized in the reactive region. This relation forms the basis of the calculation of k(t) through Brownian dynamics simulations. Two simulation procedures involving the propagation of nonreactive trajectories initiated only from the reactive region are described and illustrated on a model system. Both analytical and simulation results demonstrate the accuracy of the equilibrium-distribution approximation method. PMID:8913584

  2. Sequential effects and sequence learning in a three-choice serial reaction time task.

    PubMed

    Lee, Jessica C; Beesley, Tom; Livesey, Evan J

    2016-10-01

    The recent history of events can influence responding despite there being no contingent relationship between those events. These 'sequential effects' are ubiquitous in cognitive psychology, yet their study has been dominated by two-choice reaction time tasks in which sequences necessarily comprise simple response repetitions and alternations. The current study explored sequential effects in a three-choice reaction time task where the target was constrained to either move clockwise or anticlockwise on each trial, allowing for assessment of sequential effects involving the direction of target transitions rather than target location. Across two experiments, a reliable pattern of sequential effects was found in the absence of contingencies, whereby the most notable feature was that participants were fastest to respond to subsequences where the target moved in a consistent direction on consecutive trials, compared to when the target direction alternated. In Experiment 2, the direction of motion was biased to move in one direction 75% of the time and in a subsequent transfer phase, participants showed evidence of learning this probabilistic sequence but still exhibited the same pattern of sequential effects on trials where the target moved in the more prevalent or less prevalent direction. Simulations with a connectionist model of sequence learning (the Augmented Serial Recurrent Network, Cleeremans & McClelland, 1991) produced an adequate replication of the sequential effects in both experiments in addition to an effect of sequence learning in Experiment 2. We propose that sequential effects may represent learning about transient contingencies and may be described using the same associative learning mechanisms intended for sequence learning.

  3. Age-related differences in muscle recruitment and reaction-time performance.

    PubMed

    Arnold, Pauline; Vantieghem, Stijn; Gorus, Ellen; Lauwers, Elien; Fierens, Yves; Pool-Goudzwaard, Annelies; Bautmans, Ivan

    2015-10-01

    Previously, we showed that prolonged reaction-time (RT) in older persons is related to increased antagonist muscle co-activation, occurring already before movement onset. Here, we studied whether a difference in temporal agonist and antagonist muscle activation exists between young and older persons during an RT-test. We studied Mm. Biceps (antagonist muscle) & Triceps (agonist muscle) Brachii activation time by sEMG in 60 young (26 ± 3 years) and 64 older (80 ± 6 years) community-dwelling subjects during a simple point-to-point RT-test (moving a finger using standardized elbow-extension from one pushbutton to another following a visual stimulus). RT was divided in pre-movement-time (PMT, time for stimulus processing) and movement-time (MT, time for motor response completion). Muscle activation time 1) following stimulus onset (PMAT) and 2) before movement onset (MAT) was calculated. PMAT for both muscles was significantly longer for the older subjects compared to the young (258 ± 53 ms versus 224 ± 37 ms, p=0.042 for Biceps and 280 ± 70 ms versus 218 ± 43 ms for Triceps, p<0.01). Longer agonist muscle PMAT was significantly related to worse PMT and RT in young (respectively r=0.76 & r=0.68, p<0.001) and elderly (respectively r=0.42 & r=0.40, p=0.001). In the older subjects we also found that the antagonist muscle activated significantly earlier than the agonist muscle (-22 ± 55 ms, p=0.003). We conclude that in older persons, besides the previously reported increased antagonist muscle co-activation, the muscle firing sequence is also profoundly altered. This is characterized by a delayed muscle activation following stimulus onset, and a significantly earlier recruitment of the antagonist muscle before movement onset.

  4. Time course of expiratory propofol after bolus injection as measured by ion molecule reaction mass spectrometry.

    PubMed

    Hornuss, Cyrill; Wiepcke, Dirk; Praun, Siegfried; Dolch, Michael E; Apfel, Christian C; Schelling, Gustav

    2012-04-01

    Propofol in exhaled breath can be detected and monitored in real time by ion molecule reaction mass spectrometry (IMR-MS). In addition, propofol concentration in exhaled breath is tightly correlated with propofol concentration in plasma. Therefore, real-time monitoring of expiratory propofol could be useful for titrating intravenous anesthesia, but only if concentration changes in plasma can be determined in exhaled breath without significant delay. To evaluate the utility of IMR-MS during non-steady-state conditions, we measured the time course of both expiratory propofol concentration and the processed electroencephalography (EEG) as a surrogate outcome for propofol effect after an IV bolus induction of propofol. Twenty-one patients scheduled for routine surgery were observed after a bolus of 2.5 mg kg(-1) propofol for induction of anesthesia. Expiratory propofol was measured using IMR-MS and the cerebral propofol effect was estimated using the bispectral index (BIS). Primary endpoints were time to detection of expiratory propofol and time to onset of propofol's effect on BIS, and the secondary endpoint was time to peak effect (highest expiratory propofol or lowest BIS). Expiratory propofol and changes in BIS were first detected at 43 ± 21 and 49 ± 11 s after bolus injection, respectively (P = 0.29). Peak propofol concentrations (9.2 ± 2.4 parts-per-billion) and lowest BIS values (23 ± 4) were reached after 208 ± 57 and 219 ± 62 s, respectively (P = 0.57). Expiratory propofol concentrations measured by IMR-MS have similar times to detection and peak concentrations compared with propofol effect as measured by the processed EEG (BIS). This suggests that expiratory propofol concentrations may be useful for titrating intravenous anesthesia.

  5. Sleep restriction and degraded reaction-time performance in Figaro solo sailing races.

    PubMed

    Hurdiel, Rémy; Van Dongen, Hans P A; Aron, Christophe; McCauley, Peter; Jacolot, Laure; Theunynck, Denis

    2014-01-01

    In solo offshore sailing races like those of the Solitaire du Figaro, sleep must be obtained in multiple short bouts to maintain competitive performance and safety. Little is known about the amount of sleep restriction experienced at sea and the effects that fatigue from sleep loss have on sailors' performance. Therefore, we assessed sleep in sailors of yachts in the Figaro 2 Beneteau class during races and compared response times on a serial simple reaction-time test before and after races. Twelve men (professional sailors) recorded their sleep and measured their response times during one of the three single-handed races of 150, 300 and 350 nautical miles (nominally 24-50 h in duration). Total estimated sleep duration at sea indicated considerable sleep insufficiency. Response times were slower after races than before. The results suggest that professional sailors incur severe sleep loss and demonstrate marked performance impairment when competing in one- to two-day solo sailing races. Competitive performance could be improved by actively managing sleep during solo offshore sailing races.

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

    PubMed

    Schatz, Philip; Ybarra, Vincent; Leitner, Donald

    2015-08-01

    Computer-based assessment has evolved to tablet-based devices. Despite the availability of tablets and "apps," there is limited research validating their use. We documented timing delays between stimulus presentation and (simulated) touch response on iOS devices (3rd- and 4th-generation Apple iPads) and Android devices (Kindle Fire, Google Nexus, Samsung Galaxy) at response intervals of 100, 250, 500, and 1,000 milliseconds (ms). Results showed significantly greater timing error on Google Nexus and Samsung tablets (81-97 ms), than Kindle Fire and Apple iPads (27-33 ms). Within Apple devices, iOS 7 obtained significantly lower timing error than iOS 6. Simple reaction time (RT) trials (250 ms) on tablet devices represent 12% to 40% error (30-100 ms), depending on the device, which decreases considerably for choice RT trials (3-5% error at 1,000 ms). Results raise implications for using the same device for serial clinical assessment of RT using tablets, as well as the need for calibration of software and hardware. PMID:25612627

  7. Femtosecond real-time probing of reactions. IX. Hydrogen-atom transfer

    NASA Astrophysics Data System (ADS)

    Herek, J. L.; Pedersen, S.; Bañares, L.; Zewail, A. H.

    1992-12-01

    The real-time dynamics of hydrogen-atom-transfer processes under collisionless conditions are studied using femtosecond depletion techniques. The experiments focus on the methyl salicylate system, which exhibits ultrafast hydrogen motion between two oxygen atoms due to molecular tautomerization, loosely referred to as intramolecular ``proton'' transfer. To test for tunneling and mass effects on the excited potential surface, we also studied deuterium and methyl-group substitutions. We observe that the motion of the hydrogen, under collisionless conditions, takes place within 60 fs. At longer times, on the picosecond time scale, the hydrogen-transferred form decays with a threshold of 15.5 kJ/mol; this decay behavior was observed up to a total vibrational energy of ˜7200 cm-1. The observed dynamics provide the global nature of the motion, which takes into account bonding before and after the motion, and the evolution of the wave packet from the initial nonequilibrium state to the transferred form along the O-H—O reaction coordinate. The vibrational periods (2π/ω) of the relevant modes range from 13 fs (the OH stretch) to 190 fs (the low-frequency distortion) and the motion involves (in part) these coordinates. The intramolecular vibrational-energy redistribution dynamics at longer times are important to the hydrogen-bond dissociation and to the nonradiative decay of the hydrogen-transferred form.

  8. Determination of Sperm Sex Ratio in Bovine Semen Using Multiplex Real-time Polymerase Chain Reaction.

    PubMed

    Khamlor, Trisadee; Pongpiachan, Petai; Sangsritavong, Siwat; Chokesajjawatee, Nipa

    2014-10-01

    Gender selection is important in livestock industries; for example, female calves are required in the dairy industry. Sex-sorted semen is commonly used for the production of calves of the desired gender. However, assessment of the sex ratio of the sorted semen is tedious and expensive. In this study, a rapid, cost effective and reliable method for determining the sex ratio was developed using a multiplex real-time polymerase chain reaction (PCR) assay. In this assay, the X and Y chromosome-specific markers, i.e., bovine proteolipid protein (PLP) gene and sex-determining region Y (SRY) were simultaneously quantified in a single tube. The multiplex real-time PCR assay was shown to have high amplification efficiencies (97% to 99%) comparable to the separated-tube simplex real-time PCR assay. The results obtained from both assays were not significantly different (p>0.05). The multiplex assay was validated using reference DNA of known X ratio (10%, 50%, and 90%) as templates. The measured %X in semen samples were the same within 95% confidence intervals as the expected values, i.e., >90% in X-sorted semen, <10% in Y-sorted semen and close to 50% in the unsorted semen. The multiplex real-time PCR assay as shown in this study can thus be used to assess purity of sex-sorted semen. PMID:25178292

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

    PubMed

    Schatz, Philip; Ybarra, Vincent; Leitner, Donald

    2015-08-01

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

  10. A Time-Dependent Quantum Dynamics Study of the H2 + CH3 yields H + CH4 Reaction

    NASA Technical Reports Server (NTRS)

    Wang, Dunyou; Kwak, Dochan (Technical Monitor)

    2002-01-01

    We present a time-dependent wave-packet propagation calculation for the H2 + CH3 yields H + CH4 reaction in six degrees of freedom and for zero total angular momentum. Initial state selected reaction probability for different initial rotational-vibrational states are presented in this study. The cumulative reaction probability (CRP) is obtained by summing over initial-state-selected reaction probability. The energy-shift approximation to account for the contribution of degrees of freedom missing in the 6D calculation is employed to obtain an approximate full-dimensional CRP. Thermal rate constant is compared with different experiment results.

  11. Time-resolved analysis of biological reactions based on heterogeneous assays in liquid plugs of nanoliter volume.

    PubMed

    Rendl, Martin; Brandstetter, Thomas; Rühe, Jürgen

    2013-10-15

    In this article, we present a concept which uses liquid plugs as reaction volumes for heterogeneous assay reactions to facilitate time-resolved analysis of biomolecular reactions. For this purpose, the reaction is first compartmentalized to a train of many identical plugs. Therefore, we established a simple fluidic setup build from off-the-shelf available tubing and connectors. It permits reliable formation of plugs and successive dosing of further assay reagents to these compartments (plug volume <5% CV). The time course of the reaction is obtained by routing the plugs successively through a detector. Thereby, the arrival time of a given plug at the detector represents the reaction time of the overall reaction at that moment. Thus, each analyzed plug represents a discrete state of the overall reaction. With this approach, we can achieve a temporal resolution as small as one second, which hardly can be met by conventional analytical methods for analysis of endogenous biological compounds. For analysis of the content of the plugs, we developed a method which allows for heterogeneous assays in two-phase flow. For this purpose, functionalized superparamagnetic beads are enclosed in the plugs for specific binding of the assay product. Purification from supernatant species is achieved by transferring the beads with bound analyte across the phase boundary between aqueous plugs and water-immiscible carrier fluid. We demonstrate this assay principle exemplarily for a sandwich immunoassay (cytokine IL-8). Time-resolved analysis is validated by monitoring a cell-free in vitro expression reaction (turboGFP) in plugs and conventionally in bulk solution. We show that our approach allows for analyzing the entire course of a reaction in a single run. It permits kinetic studies of biological processes with significantly reduced experimental effort and consumption of costly reagents. PMID:24083685

  12. Photonuclear reactions studied with the time-dependent density-functional theory

    NASA Astrophysics Data System (ADS)

    Nakatsukasa, Takashi

    2009-10-01

    Photonuclear reaction cross sections are known to be of fundamental importance in nuclear structure as well as a variety of applications, such as nucleosynthesis and nuclear power. Especially, it is highly desired to improve reliability of E1 strength distribution in unstable nuclei which are not experimentally reachable. We are performing systematic calculations of nuclear photoabsorption cross sections using the time-dependent density-functional theory. For this purpose, we have developed a new numerical approach to the linear response problems, ``Finite Amplitude Method'' (FAM). In this talk, we present recent results of our microscopic calculations with the FAM applied to the Skyrme functionals and discuss properties of nuclear E1 strength distribution in light- and medium-mass nuclei.

  13. Adobe Flash as a medium for online experimentation: a test of reaction time measurement capabilities.

    PubMed

    Reimers, Stian; Stewart, Neil

    2007-08-01

    Adobe Flash can be used to run complex psychological experiments over the Web. We examined the reliability of using Flash to measure reaction times (RTs) using a simple binary-choice task implemented both in Flash and in a Linux-based system known to record RTs with millisecond accuracy. Twenty-four participants were tested in the laboratory using both implementations; they also completed the Flash version on computers of their own choice outside the lab. RTs from the trials run on Flash outside the lab were approximately 20 msec slower than those from trials run on Flash in the lab, which in turn were approximately 10 msec slower than RTs from the trials run on the Linux-based system (baseline condition). RT SDs were similar in all conditions, suggesting that although Flash may overestimate RTs slightly, it does not appear to add significant noise to the data recorded.

  14. Attentional disengagement is modulated by the offset of unpleasant pictures: a saccadic reaction time study.

    PubMed

    Machado-Pinheiro, Walter; Faria, Aydamari; Braga, Filipe; Guerra, Pedro; Perakakis, Pandelis; Caldas, Ariane Leão; Mocaiber, Izabela; Oliveira, Letícia; Pereira, Mirtes Garcia; Volchan, Eliane; Vila, Jaime

    2013-12-01

    We studied the influence of passively viewing a picture on saccade latencies to peripheral targets. Thirty-two volunteers were instructed to look at a central picture, wait for the onset of a peripheral target, and execute a saccade toward it as quickly as possible - saccadic reaction time (SRT). The central picture (neutral or unpleasant) could be turned off simultaneously with target onset (the no-gap condition) or 200ms prior to target onset (the gap-200 condition). We found that saccade latencies were influenced by emotional valence and condition. In the no-gap condition, SRTs were longer after viewing unpleasant pictures. In the gap-200 condition, the pattern was reversed, and unpleasant pictures induced shorter SRTs in relation to neutral pictures. Furthermore, the influence of unpleasant pictures gradually decreased when images were re-exposed to the participants - affective habituation. The results are discussed in terms of attentional avoidance and disengagement from unpleasant emotional pictures. PMID:24177247

  15. Space positional and motion SRC effects: A comparison with the use of reaction time distribution analysis

    PubMed Central

    Styrkowiec, Piotr; Szczepanowski, Remigiusz

    2013-01-01

    The analysis of reaction time (RT) distributions has become a recognized standard in studies on the stimulus response correspondence (SRC) effect as it allows exploring how this effect changes as a function of response speed. In this study, we compared the spatial SRC effect (the classic Simon effect) with the motion SRC effect using RT distribution analysis. Four experiments were conducted, in which we manipulated factors of space position and motion for stimulus and response, in order to obtain a clear distinction between positional SRC and motion SRC. Results showed that these two types of SRC effects differ in their RT distribution functions as the space positional SRC effect showed a decreasing function, while the motion SRC showed an increasing function. This suggests that different types of codes underlie these two SRC effects. Potential mechanisms and processes are discussed. PMID:24605178

  16. Action Video Games Improve Direction Discrimination of Parafoveal Translational Global Motion but Not Reaction Times.

    PubMed

    Pavan, Andrea; Boyce, Matthew; Ghin, Filippo

    2016-10-01

    Playing action video games enhances visual motion perception. However, there is psychophysical evidence that action video games do not improve motion sensitivity for translational global moving patterns presented in fovea. This study investigates global motion perception in action video game players and compares their performance to that of non-action video game players and non-video game players. Stimuli were random dot kinematograms presented in the parafovea. Observers discriminated the motion direction of a target random dot kinematogram presented in one of the four visual quadrants. Action video game players showed lower motion coherence thresholds than the other groups. However, when the task was performed at threshold, we did not find differences between groups in terms of distributions of reaction times. These results suggest that action video games improve visual motion sensitivity in the near periphery of the visual field, rather than speed response. PMID:27495185

  17. Reaction time signatures of discriminative processes: differential effects of stimulus similarity and incentive.

    PubMed

    Blough, Donald S

    2004-05-01

    In three experiments with pigeons, the similarity of unreinforced test stimuli to a reinforced stimulus and the frequency of reinforcement associated with a stimulus were varied. The stimulus on each trial was a small spot that appeared in different hues or, in Experiment 3, different forms. Differential response frequency and reaction time (RT) patterns emerged: Changes in similarity affected the percentage of stimuli responded to but left the shape of RT distributions about the same, whereas changes in reinforcement shifted RT distributions but had little effect on the percentage of responses. When the similarity and reinforcement variables were applied to the same stimuli (Experiment 2), their effects were largely independent. A generalization procedure (Experiment 3) replicated the similarity effects of the initial discrimination procedure. The RT distributions were modeled by a diffusion process, and implications for a memory-instance model were suggested.

  18. The structure of motor programming: evidence from reaction times and lateralized readiness potentials.

    PubMed

    Xu, Lu; Sommer, Werner; Masaki, Hiroaki

    2015-01-01

    There is a widely accepted notion that movement elements are assembled prior to movement execution in a central motor programming stage. However, it is not clear how this stage is structured-whether it is a unitary stage allowing different motor parameters to cross talk or whether there are several independent processes dealing with each motor parameter. We addressed this question by orthogonally manipulating two movement-related factors: response sequence complexity and movement duration. Both factors yielded main effects on reaction time but no interaction. Additive effects of both factors on the onsets of response- but not stimulus-synchronized lateralized readiness potentials suggest separable motoric loci of sequence complexity and duration. These findings are at variance with the notion of a unitary movement programming stage. PMID:25082470

  19. Rethinking spontaneous giving: Extreme time pressure and ego-depletion favor self-regarding reactions.

    PubMed

    Capraro, Valerio; Cococcioni, Giorgia

    2016-01-01

    Previous experimental studies suggest that cooperation in one-shot anonymous interactions is, on average, spontaneous, rather than calculative. To explain this finding, it has been proposed that people internalize cooperative heuristics in their everyday life and bring them as intuitive strategies in new and atypical situations. Yet, these studies have important limitations, as they promote intuitive responses using weak time pressure or conceptual priming of intuition. Since these manipulations do not deplete participants' ability to reason completely, it remains unclear whether cooperative heuristics are really automatic or they emerge after a small, but positive, amount of deliberation. Consistent with the latter hypothesis, we report two experiments demonstrating that spontaneous reactions in one-shot anonymous interactions tend to be egoistic. In doing so, our findings shed further light on the cognitive underpinnings of cooperation, as they suggest that cooperation in one-shot interactions is not automatic, but appears only at later stages of reasoning. PMID:27251762

  20. Processing of emotion words by patients with autism spectrum disorders: evidence from reaction times and EEG.

    PubMed

    Lartseva, Alina; Dijkstra, Ton; Kan, Cornelis C; Buitelaar, Jan K

    2014-11-01

    This study investigated processing of emotion words in autism spectrum disorders (ASD) using reaction times and event-related potentials (ERP). Adults with (n = 21) and without (n = 20) ASD performed a lexical decision task on emotion and neutral words while their brain activity was recorded. Both groups showed faster responses to emotion words compared to neutral, suggesting intact early processing of emotion in ASD. In the ERPs, the control group showed a typical late positive component (LPC) at 400-600 ms for emotion words compared to neutral, while the ASD group showed no LPC. The between-group difference in LPC amplitude was significant, suggesting that emotion words were processed differently by individuals with ASD, although their behavioral performance was similar to that of typical individuals.

  1. Rethinking spontaneous giving: Extreme time pressure and ego-depletion favor self-regarding reactions

    PubMed Central

    Capraro, Valerio; Cococcioni, Giorgia

    2016-01-01

    Previous experimental studies suggest that cooperation in one-shot anonymous interactions is, on average, spontaneous, rather than calculative. To explain this finding, it has been proposed that people internalize cooperative heuristics in their everyday life and bring them as intuitive strategies in new and atypical situations. Yet, these studies have important limitations, as they promote intuitive responses using weak time pressure or conceptual priming of intuition. Since these manipulations do not deplete participants’ ability to reason completely, it remains unclear whether cooperative heuristics are really automatic or they emerge after a small, but positive, amount of deliberation. Consistent with the latter hypothesis, we report two experiments demonstrating that spontaneous reactions in one-shot anonymous interactions tend to be egoistic. In doing so, our findings shed further light on the cognitive underpinnings of cooperation, as they suggest that cooperation in one-shot interactions is not automatic, but appears only at later stages of reasoning. PMID:27251762

  2. 7Li-induced reactions for fast-timing with LaBr3:Ce detectors

    NASA Astrophysics Data System (ADS)

    Mason, P. J. R.; Podolyàk, Zs.; Mǎrginean, N.; Regan, P. H.; Alexander, T.; Algora, A.; Alharbi, T.; Bowry, M.; Britton, R.; Bucurescu, D.; Bruce, A. M.; Bunce, M.; Cǎta-Danil, G.; Cǎta-Danil, I.; Cooper, N.; Deleanu, D.; Delion, D.; Filipescu, D.; Gelletly, W.; Glodariu, T.; Gheorghe, I.; Ghiťǎ, D.; Ilie, G.; Ivanova, D.; Kisyov, S.; Lalkovski, S.; Lica, R.; Liddick, S. N.; Mǎrginean, R.; Mihai, C.; Mulholland, K.; Negret, A.; Nita, C. R.; Rice, S.; Roberts, O. J.; Sava, T.; Smith, J. F.; Söderström, P.-A.; Stevenson, P. D.; Stroe, L.; Toma, S.; Townsley, C.; Werner, V.; Wilson, E.; Wood, R. T.; Zamfir, N. V.; Zhekova, M.

    2012-10-01

    7Li induced-reactions have been used with a 186W target to populate nuclei around A˜180-190 at the National Institute of Physics and Nuclear Engineering in Bucharest, Romania. An array of high-purity germanium (HPGe) and cerium-doped lanthanum bromide (LaBr3:Ce) detectors have been used to measure sub-nanosecond half-lives with fast-timing techniques. The yrast 2+ state in 190Os was measured to be t1/2 = 375(20)ps, in excellent agreement with the literature value. The previously unreported half-life of the 564-keV state in 189Ir has also been measured and a value of t1/2 = 540(100)ps ps obtained.

  3. How Does the Driver’s Perception Reaction Time Affect the Performances of Crash Surrogate Measures?

    PubMed Central

    Kuang, Yan; Qu, Xiaobo; Weng, Jinxian; Etemad-Shahidi, Amir

    2015-01-01

    With the merit on representing traffic conflict through examining the crash mechanism and causality proactively, crash surrogate measures have long been proposed and applied to evaluate the traffic safety. However, the driver’s Perception-Reaction Time (PRT), an important variable in crash mechanism, has not been considered widely into surrogate measures. In this regard, it is important to know how the PRT affects the performances of surrogate indicators. To this end, three widely used surrogate measures are firstly modified by involving the PRT into their crash mechanisms. Then, in order to examine the difference caused by the PRT, a comparative study is carried out on a freeway section of the Pacific Motorway, Australia. This result suggests that the surrogate indicators’ performances in representing rear-end crash risks are improved with the incorporating of the PRT for the investigated section. PMID:26398416

  4. Action Video Games Improve Direction Discrimination of Parafoveal Translational Global Motion but Not Reaction Times.

    PubMed

    Pavan, Andrea; Boyce, Matthew; Ghin, Filippo

    2016-10-01

    Playing action video games enhances visual motion perception. However, there is psychophysical evidence that action video games do not improve motion sensitivity for translational global moving patterns presented in fovea. This study investigates global motion perception in action video game players and compares their performance to that of non-action video game players and non-video game players. Stimuli were random dot kinematograms presented in the parafovea. Observers discriminated the motion direction of a target random dot kinematogram presented in one of the four visual quadrants. Action video game players showed lower motion coherence thresholds than the other groups. However, when the task was performed at threshold, we did not find differences between groups in terms of distributions of reaction times. These results suggest that action video games improve visual motion sensitivity in the near periphery of the visual field, rather than speed response.

  5. Left anterior cingulate activity predicts intra-individual reaction time variability in healthy adults.

    PubMed

    Johnson, Beth P; Pinar, Ari; Fornito, Alex; Nandam, L Sanjay; Hester, Robert; Bellgrove, Mark A

    2015-06-01

    Within-subject, or intra-individual, variability in reaction time (RT) is increasingly recognised as an important indicator of the efficiency of attentional control, yet there have been few investigations of the neural correlates of trial-to-trial RT variability in healthy adults. We sought to determine the neural correlates of intra-individual RT variability during a go/no-go response inhibition task in 27 healthy, male participants. We found that reduced trial-to-trial RT variability (i.e. greater response stability) was significantly associated with greater activation in the left pregenual anterior cingulate. These results support the role of the left anterior cingulate in the dynamic control of attention and efficient response selection. Greater understanding of intra-individual RT variability and top-down attentional control in healthy adults may help to inform disorders that impact executive/attentional control, such as attention deficit hyperactivity disorder and schizophrenia. PMID:25791710

  6. Influence of cup stacking on hand-eye coordination and reaction time of second-grade students.

    PubMed

    Udermann, Brian E; Murray, Steven R; Mayer, John M; Sagendorf, Kenneth

    2004-04-01

    Cup stacking has been adopted recently by many physical education programs to enhance rudimentary motor skills such as hand-eye coordination and ambidexterity as well as quickness and concentration; however, no empirical evidence has been published to support these claims. We examined the influence of cup stacking on hand-eye coordination and reaction time of 24 boys and 18 girls in second grade as measured by the Soda Pop and Yardstick tests, respectively. Two physical education classes were randomly assigned as treatment and control groups and were pre- and posttested for hand-eye coordination and reaction time. The treatment group participated in a 5-wk. cup-stacking program. Significant improvements were noted for both hand-eye coordination and reaction time between the pre- and posttest scores for this group but not for the control group. Therefore, cup stacking is indeed effective in enhancing hand-eye coordination and reaction time. PMID:15141904

  7. Effect of Buddhist meditation on serum cortisol and total protein levels, blood pressure, pulse rate, lung volume and reaction time.

    PubMed

    Sudsuang, R; Chentanez, V; Veluvan, K

    1991-09-01

    Serum cortisol and total protein levels, blood pressure, heart rate, lung volume, and reaction time were studied in 52 males 20-25 years of age practicing Dhammakaya Buddhist meditation, and in 30 males of the same age group not practicing meditation. It was found that after meditation, serum cortisol levels were significantly reduced, serum total protein level significantly increased, and systolic pressure, diastolic pressure and pulse rate significantly reduced. Vital capacity, tidal volume and maximal voluntary ventilation were significantly lower after meditation than before. There were also significant decreases in reaction time after mediation practice. The percentage decrease in reaction time during meditation was 22%, while in subjects untrained in meditation, the percentage decrease was only 7%. Results from these studies indicate that practising Dhammakaya Buddhist meditation produces biochemical and physiological changes and reduces the reaction time.

  8. The Relationship between Saccadic Choice and Reaction Times with Manipulations of Target Value.

    PubMed

    Milstein, David M; Dorris, Michael C

    2011-01-01

    Choosing the option with the highest expected value (EV; reward probability × reward magnitude) maximizes the intake of reward under conditions of uncertainty. However, human economic choices indicate that our value calculation has a subjective component whereby probability and reward magnitude are not linearly weighted. Using a similar economic framework, our goal was to characterize how subjective value influences the generation of simple motor actions. Specifically, we hypothesized that attributes of saccadic eye movements could provide insight into how rhesus monkeys, a well-studied animal model in cognitive neuroscience, subjectively value potential visual targets. In the first experiment, monkeys were free to choose by directing a saccade toward one of two simultaneously displayed targets, each of which had an uncertain outcome. In this task, choices were more likely to be allocated toward the higher valued target. In the second experiment, only one of the two possible targets appeared on each trial. In this task, saccadic reaction times (SRTs) decreased toward the higher valued target. Reward magnitude had a much stronger influence on both choices and SRTs than probability, whose effect was observed only when reward magnitude was similar for both targets. Across EV blocks, a strong relationship was observed between choice preferences and SRTs. However, choices tended to maximize at skewed values whereas SRTs varied more continuously. Lastly, SRTs were unchanged when all reward magnitudes were 1×, 1.5×, and 2× their normal amount, indicating that saccade preparation was influenced by the relative value of the targets rather than the absolute value of any single-target. We conclude that value is not only an important factor( )for deliberative decision making in primates, but also for the selection and preparation of simple motor actions, such as saccadic eye movements. More precisely, our results indicate that, under conditions of uncertainty

  9. Cybersickness provoked by head-mounted display affects cutaneous vascular tone, heart rate and reaction time.

    PubMed

    Nalivaiko, Eugene; Davis, Simon L; Blackmore, Karen L; Vakulin, Andrew; Nesbitt, Keith V

    2015-11-01

    Evidence from studies of provocative motion indicates that motion sickness is tightly linked to the disturbances of thermoregulation. The major aim of the current study was to determine whether provocative visual stimuli (immersion into the virtual reality simulating rides on a rollercoaster) affect skin temperature that reflects thermoregulatory cutaneous responses, and to test whether such stimuli alter cognitive functions. In 26 healthy young volunteers wearing head-mounted display (Oculus Rift), simulated rides consistently provoked vection and nausea, with a significant difference between the two versions of simulation software (Parrot Coaster and Helix). Basal finger temperature had bimodal distribution, with low-temperature group (n=8) having values of 23-29 °C, and high-temperature group (n=18) having values of 32-36 °C. Effects of cybersickness on finger temperature depended on the basal level of this variable: in subjects from former group it raised by 3-4 °C, while in most subjects from the latter group it either did not change or transiently reduced by 1.5-2 °C. There was no correlation between the magnitude of changes in the finger temperature and nausea score at the end of simulated ride. Provocative visual stimulation caused prolongation of simple reaction time by 20-50 ms; this increase closely correlated with the subjective rating of nausea. Lastly, in subjects who experienced pronounced nausea, heart rate was elevated. We conclude that cybersickness is associated with changes in cutaneous thermoregulatory vascular tone; this further supports the idea of a tight link between motion sickness and thermoregulation. Cybersickness-induced prolongation of reaction time raises obvious concerns regarding the safety of this technology. PMID:26340855

  10. Inhibitory effects of atrazine on Chlorella vulgaris as assessed by real-time polymerase chain reaction.

    PubMed

    Qian, Haifeng; Daniel Sheng, G; Liu, Weiping; Lu, Yingcong; Liu, Zhenghai; Fu, Zhengwei

    2008-01-01

    Atrazine, a highly toxic herbicide, is frequently detected in surface water because of its heavy application. Algae are among the aquatic organisms most susceptible to atrazine pollution in water. In the present study, the aquatic alga Chlorella vulgaris Beijerinck was chosen to assess the acute toxicity of atrazine (48-96 h) in terms of gene transcription and physiological changes. A real-time polymerase chain reaction (PCR) assay was used to quantify transcript levels of three photosystem genes in C. vulgaris. The diel patterns for regulation of the psaB (photosystem I reaction center protein subunit B), psbC (an integral membrane protein component of photosystem II), and rbcL (large subunit of ribulose-1,5-bisphosphate carboxylase oxygenase) gene transcripts were successfully quantified. Results showed that atrazine reduced the transcript abundances of three target genes and that the abundances decreased with increasing atrazine concentration. The determined smallest transcript levels of psaB, psbC, and rbcL, which occurred at the highest atrazine concentration tested (400 mug/L), were only 34.6, 34.6, and 8.1%, respectively, of the control sample value. Exposure to atrazine increased the level of malondialdehyde by 1.74-fold (the highest value) in C. vulgaris, suggesting potential oxidative damage to the alga. The activities of antioxidation enzymes (e.g., superoxide dismutase, peroxidase, and catalase) also increased markedly in the presence of atrazine, with maximum increases of 1.82-, 1.59-, and 2.31-fold, respectively. These elevated activities may help to alleviate the oxidative damage. Our results demonstrate that atrazine is highly toxic to this alga and that real-time PCR is an efficient technique for assessing the toxicity of xenobiotic compounds in algae.

  11. Cybersickness provoked by head-mounted display affects cutaneous vascular tone, heart rate and reaction time.

    PubMed

    Nalivaiko, Eugene; Davis, Simon L; Blackmore, Karen L; Vakulin, Andrew; Nesbitt, Keith V

    2015-11-01

    Evidence from studies of provocative motion indicates that motion sickness is tightly linked to the disturbances of thermoregulation. The major aim of the current study was to determine whether provocative visual stimuli (immersion into the virtual reality simulating rides on a rollercoaster) affect skin temperature that reflects thermoregulatory cutaneous responses, and to test whether such stimuli alter cognitive functions. In 26 healthy young volunteers wearing head-mounted display (Oculus Rift), simulated rides consistently provoked vection and nausea, with a significant difference between the two versions of simulation software (Parrot Coaster and Helix). Basal finger temperature had bimodal distribution, with low-temperature group (n=8) having values of 23-29 °C, and high-temperature group (n=18) having values of 32-36 °C. Effects of cybersickness on finger temperature depended on the basal level of this variable: in subjects from former group it raised by 3-4 °C, while in most subjects from the latter group it either did not change or transiently reduced by 1.5-2 °C. There was no correlation between the magnitude of changes in the finger temperature and nausea score at the end of simulated ride. Provocative visual stimulation caused prolongation of simple reaction time by 20-50 ms; this increase closely correlated with the subjective rating of nausea. Lastly, in subjects who experienced pronounced nausea, heart rate was elevated. We conclude that cybersickness is associated with changes in cutaneous thermoregulatory vascular tone; this further supports the idea of a tight link between motion sickness and thermoregulation. Cybersickness-induced prolongation of reaction time raises obvious concerns regarding the safety of this technology.

  12. Multi-capillary-column proton-transfer-reaction time-of-flight mass spectrometry☆

    PubMed Central

    Ruzsanyi, Veronika; Fischer, Lukas; Herbig, Jens; Ager, Clemes; Amann, Anton

    2013-01-01

    Proton-transfer-reaction time-of-flight mass-spectrometry (PTR-TOFMS) exhibits high selectivity with a resolution of around 5000 m/Δm. While isobars can be separated with this resolution, discrimination of isomeric compounds is usually not possible. The coupling of a multi-capillary column (MCC) with a PTR-TOFMS overcomes these problems as demonstrated in this paper for the ketone isomers 3-heptanone and 2-methyl-3-hexanone and for different aldehydes. Moreover, fragmentation of compounds can be studied in detail which might even improve the identification. LODs for compounds tested are in the range of low ppbv and peak positions of the respective separated substances show good repeatability (RSD of the peak positions <3.2%). Due to its special characteristics, such as isothermal operation, compact size, the MCC setup is suitable to be installed inside the instrument and the overall retention time for a complete spectrum is only a few minutes: this allows near real-time measurements in the optional MCC mode. In contrast to other methods that yield additional separation, such as the use of pre-cursor ions other than H3O+, this method yields additional information without increasing complexity. PMID:24119758

  13. Cortical Components of Reaction-Time during Perceptual Decisions in Humans

    PubMed Central

    Dmochowski, Jacek P.; Norcia, Anthony M.

    2015-01-01

    The mechanisms of perceptual decision-making are frequently studied through measurements of reaction time (RT). Classical sequential-sampling models (SSMs) of decision-making posit RT as the sum of non-overlapping sensory, evidence accumulation, and motor delays. In contrast, recent empirical evidence hints at a continuous-flow paradigm in which multiple motor plans evolve concurrently with the accumulation of sensory evidence. Here we employ a trial-to-trial reliability-based component analysis of encephalographic data acquired during a random-dot motion task to directly image continuous flow in the human brain. We identify three topographically distinct neural sources whose dynamics exhibit contemporaneous ramping to time-of-response, with the rate and duration of ramping discriminating fast and slow responses. Only one of these sources, a parietal component, exhibits dependence on strength-of-evidence. The remaining two components possess topographies consistent with origins in the motor system, and their covariation with RT overlaps in time with the evidence accumulation process. After fitting the behavioral data to a popular SSM, we find that the model decision variable is more closely matched to the combined activity of the three components than to their individual activity. Our results emphasize the role of motor variability in shaping RT distributions on perceptual decision tasks, suggesting that physiologically plausible computational accounts of perceptual decision-making must model the concurrent nature of evidence accumulation and motor planning. PMID:26599741

  14. Cortical Components of Reaction-Time during Perceptual Decisions in Humans.

    PubMed

    Dmochowski, Jacek P; Norcia, Anthony M

    2015-01-01

    The mechanisms of perceptual decision-making are frequently studied through measurements of reaction time (RT). Classical sequential-sampling models (SSMs) of decision-making posit RT as the sum of non-overlapping sensory, evidence accumulation, and motor delays. In contrast, recent empirical evidence hints at a continuous-flow paradigm in which multiple motor plans evolve concurrently with the accumulation of sensory evidence. Here we employ a trial-to-trial reliability-based component analysis of encephalographic data acquired during a random-dot motion task to directly image continuous flow in the human brain. We identify three topographically distinct neural sources whose dynamics exhibit contemporaneous ramping to time-of-response, with the rate and duration of ramping discriminating fast and slow responses. Only one of these sources, a parietal component, exhibits dependence on strength-of-evidence. The remaining two components possess topographies consistent with origins in the motor system, and their covariation with RT overlaps in time with the evidence accumulation process. After fitting the behavioral data to a popular SSM, we find that the model decision variable is more closely matched to the combined activity of the three components than to their individual activity. Our results emphasize the role of motor variability in shaping RT distributions on perceptual decision tasks, suggesting that physiologically plausible computational accounts of perceptual decision-making must model the concurrent nature of evidence accumulation and motor planning. PMID:26599741

  15. The effects of baseball bat mass properties on swing mechanics, ground reaction forces, and swing timing.

    PubMed

    Laughlin, Walter A; Fleisig, Glenn S; Aune, Kyle T; Diffendaffer, Alek Z

    2016-01-01

    Swing trajectory and ground reaction forces (GRF) of 30 collegiate baseball batters hitting a pitched ball were compared between a standard bat, a bat with extra weight about its barrel, and a bat with extra weight in its handle. It was hypothesised that when compared to a standard bat, only a handle-weighted bat would produce equivalent bat kinematics. It was also hypothesised that hitters would not produce equivalent GRFs for each weighted bat, but would maintain equivalent timing when compared to a standard bat. Data were collected utilising a 500 Hz motion capture system and 1,000 Hz force plate system. Data between bats were considered equivalent when the 95% confidence interval of the difference was contained entirely within ±5% of the standard bat mean value. The handle-weighted bat had equivalent kinematics, whereas the barrel-weighted bat did not. Both weighted bats had equivalent peak GRF variables. Neither weighted bat maintained equivalence in the timing of bat kinematics and some peak GRFs. The ability to maintain swing kinematics with a handle-weighted bat may have implications for swing training and warm-up. However, altered timings of kinematics and kinetics require further research to understand the implications on returning to a conventionally weighted bat.

  16. The effects of baseball bat mass properties on swing mechanics, ground reaction forces, and swing timing.

    PubMed

    Laughlin, Walter A; Fleisig, Glenn S; Aune, Kyle T; Diffendaffer, Alek Z

    2016-01-01

    Swing trajectory and ground reaction forces (GRF) of 30 collegiate baseball batters hitting a pitched ball were compared between a standard bat, a bat with extra weight about its barrel, and a bat with extra weight in its handle. It was hypothesised that when compared to a standard bat, only a handle-weighted bat would produce equivalent bat kinematics. It was also hypothesised that hitters would not produce equivalent GRFs for each weighted bat, but would maintain equivalent timing when compared to a standard bat. Data were collected utilising a 500 Hz motion capture system and 1,000 Hz force plate system. Data between bats were considered equivalent when the 95% confidence interval of the difference was contained entirely within ±5% of the standard bat mean value. The handle-weighted bat had equivalent kinematics, whereas the barrel-weighted bat did not. Both weighted bats had equivalent peak GRF variables. Neither weighted bat maintained equivalence in the timing of bat kinematics and some peak GRFs. The ability to maintain swing kinematics with a handle-weighted bat may have implications for swing training and warm-up. However, altered timings of kinematics and kinetics require further research to understand the implications on returning to a conventionally weighted bat. PMID:26836969

  17. Using Reaction Time and Equal Latency Contours to Derive Auditory Weighting Functions in Sea Lions and Dolphins.

    PubMed

    Finneran, James J; Mulsow, Jason; Schlundt, Carolyn E

    2016-01-01

    Subjective loudness measurements are used to create equal-loudness contours and auditory weighting functions for human noise-mitigation criteria; however, comparable direct measurements of subjective loudness with animal subjects are difficult to conduct. In this study, simple reaction time to pure tones was measured as a proxy for subjective loudness in a Tursiops truncatus and Zalophus californianus. Contours fit to equal reaction-time curves were then used to estimate the shapes of auditory weighting functions.

  18. Using Reaction Time and Equal Latency Contours to Derive Auditory Weighting Functions in Sea Lions and Dolphins.

    PubMed

    Finneran, James J; Mulsow, Jason; Schlundt, Carolyn E

    2016-01-01

    Subjective loudness measurements are used to create equal-loudness contours and auditory weighting functions for human noise-mitigation criteria; however, comparable direct measurements of subjective loudness with animal subjects are difficult to conduct. In this study, simple reaction time to pure tones was measured as a proxy for subjective loudness in a Tursiops truncatus and Zalophus californianus. Contours fit to equal reaction-time curves were then used to estimate the shapes of auditory weighting functions. PMID:26610970

  19. Simple reaction time in 8-9-year old children environmentally exposed to PCBs.

    PubMed

    Šovčíková, Eva; Wimmerová, Soňa; Strémy, Maximilián; Kotianová, Janette; Loffredo, Christopher A; Murínová, Ľubica Palkovičová; Chovancová, Jana; Čonka, Kamil; Lancz, Kinga; Trnovec, Tomáš

    2015-12-01

    Simple reaction time (SRT) has been studied in children exposed to polychlorinated biphenyls (PCBs), with variable results. In the current work we examined SRT in 146 boys and 161 girls, aged 8.53 ± 0.65 years (mean ± SD), exposed to PCBs in the environment of eastern Slovakia. We divided the children into tertiles with regard to increasing PCB serum concentration. The mean ± SEM serum concentration of the sum of 15 PCB congeners was 191.15 ± 5.39, 419.23 ± 8.47, and 1315.12 ± 92.57 ng/g lipids in children of the first, second, and third tertiles, respectively. We created probability distribution plots for each child from their multiple trials of the SRT testing. We fitted response time distributions from all valid trials with the ex-Gaussian function, a convolution of a normal and an additional exponential function, providing estimates of three independent parameters μ, σ, and τ. μ is the mean of the normal component, σ is the standard deviation of the normal component, and τ is the mean of the exponential component. Group response time distributions were calculated using the Vincent averaging technique. A Q-Q plot comparing probability distribution of the first vs. third tertile indicated that deviation of the quantiles of the latter tertile from those of the former begins at the 40th percentile and does not show a positive acceleration. This was confirmed in comparison of the ex-Gaussian parameters of these two tertiles adjusted for sex, age, Raven IQ of the child, mother's and father's education, behavior at home and school, and BMI: the results showed that the parameters μ and τ significantly (p ≤ 0.05) increased with PCB exposure. Similar increases of the ex-Gaussian parameter τ in children suffering from ADHD have been previously reported and interpreted as intermittent attentional lapses, but were not seen in our cohort. Our study has confirmed that environmental exposure of children to PCBs is associated with prolongation of simple

  20. Comparative Study of Cl-Atom Reactions in Solution Using Time-Resolved Vibrational Spectroscopy.

    PubMed

    Shin, Jae Yoon; Case, Amanda S; Crim, F Fleming

    2016-04-28

    A Cl atom can react with 2,3-dimethylbutane (DMB), 2,3-dimethyl-2-butene (DMBE), and 2,5-dimethyl-2,4-hexadiene (DMHD) in solution via a hydrogen-abstraction reaction. The large exoergicity of the reaction between a Cl atom and alkenes (DMBE and DMHD) makes vibrational excitation of the HCl product possible, and we observe the formation of vibrationally excited HCl (v = 1) for both reactions. In CCl4, the branching fractions of HCl (v = 1), Γ (v = 1), for the Cl-atom reactions with DMBE and DMHD are 0.14 and 0.23, respectively, reflecting an increased amount of vibrational excitation in the products of the more exoergic reaction. In addition, Γ (v = 1) for both reactions is larger in the solvent CDCl3, being 0.23 and 0.40, as the less viscous solvent apparently dampens the vibrational excitation of the nascent HCl less effectively. The bimolecular reaction rates for the Cl reactions with DMB, DMBE, and DMHD in CCl4 are diffusion limited (having rate constants of 1.5 × 10(10), 3.6 × 10(10), and 17.5 × 10(10) M(-1) s(-1), respectively). In fact, the bimolecular reaction rate for Cl + DMHD exceeds a typical diffusion-limited reaction rate, implying that the attractive intermolecular forces between a Cl atom and a C═C bond increase the rate of favorable encounters. The 2-fold increase in the reaction rate of the Cl + DMBE reaction from that of the Cl + DMB reaction likely reflects the effect of the C═C bond, while both the number of C═C bonds and the molecular geometry likely play a role in the large reaction rate of the Cl + DMHD reaction.

  1. Airway reactions and emergence times in general laryngeal mask airway anaesthesia

    PubMed Central

    Stevanovic, Ana; Rossaint, Rolf; Fritz, Harald G.; Froeba, Gebhard; Heine, Joern; Puehringer, Friedrich K.; Tonner, Peter H.; Coburn, Mark

    2015-01-01

    BACKGROUND Desflurane's short emergence time supports fast track anaesthesia. Data on the rate of upper airway complications and emergence time when desflurane is used with laryngeal mask airway (LMA) are controversial and limited. OBJECTIVES To compare recovery time variables and the rates of upper airway adverse events in patients with an LMA undergoing general surgery with desflurane, sevoflurane, isoflurane or propofol anaesthesia. DESIGN A systematic review and meta-analysis of randomised controlled trials (RCTs). DATA SOURCES A systematic search for eligible RCTs in Embase (Elsevier) and in PubMed (National Library of Medicine) databases up to September 2013. ELIGIBILITY CRITERIA RCTs investigating the rates of cough overall, cough at emergence, laryngospasm, time to eye opening, time to removal of the LMA, time to respond to command and time to state date of birth in patients with an LMA, during emergence from desflurane, sevoflurane, isoflurane or propofol anaesthesia. RESULTS Thirteen RCTs were included and analysed. We found a strong interstudy variability. There was no difference in the rates of upper airway events between desflurane and sevoflurane or between desflurane and a control group consisting of all the other anaesthetics combined. Comparing desflurane (n = 284) with all other anaesthetic groups (n = 313), the risk ratio [95% confidence interval (95% CI)] was 1.12 (0.63 to 2.02, P = 0.70). Cough at emergence was only measured in patients receiving desflurane (n = 148) and sevoflurane (n = 146): the risk ratio (95% CI) was 1.49 (0.55 to 4.02, P = 0.43). Laryngospasm was rare and there was no significant difference in its incidence when desflurane (n = 262) was compared with all other anaesthetics combined (n = 289; risk ratio 1.03; 95% CI 0.33 to 3.20, P = 0.96). The times of all emergence variables were significantly faster in the desflurane group than in all other groups. CONCLUSION When using an LMA, upper

  2. Positive and negative stimuli in relation to tennis players' reaction time.

    PubMed

    Mead, T P; Drowatzky, J N; Hardin-Crosby, L

    2000-02-01

    Research has indicated that negative and positive thoughts may affect sport performance. The purpose of this analogue study was to assess whether negative and positive stimuli influenced tennis performance similar to positive and negative thought. The reaction time (RT) of 40 competitive tennis players was measured during a timed response to a tennis ball rotating in a topspin, sidespin, or backspin direction on the computer screen. Immediately prior to the ball presentation, a phrase (accessory stimulus) was presented visually or aurally. The accessory stimulus provided either positive (e.g., 'nice shot') or negative information (e.g., 'bad shot') followed by the subject's name. Analysis showed a main effect only for the type of spin. The slowest RT occurred when responding to a tennis ball rotating in a backspin direction. A significant interaction was found for the sensory modality (audition vs vision) and polarity (positive vs negative) of the accessory stimulus. RT to negative stimuli was slowest when the accessory stimulus was presented aurally. The quickest RT to positive stimuli occurred when the accessory stimulus was presented aurally. These results indicated that negative and positive stimuli, when presented aurally, affected performance as positive and negative thoughts measured in other studies. Not measured was whether negative and positive stimuli actually produce the negative and positive thoughts, respectively, that have been reported to affect performance.

  3. Fast but not intuitive, slow but not reflective: Decision conflict drives reaction times in social dilemmas.

    PubMed

    Evans, Anthony M; Dillon, Kyle D; Rand, David G

    2015-10-01

    When people have the chance to help others at a cost to themselves, are cooperative decisions driven by intuition or reflection? To answer this question, recent studies have tested the relationship between reaction times (RTs) and cooperation, reporting both positive and negative correlations. To reconcile this apparent contradiction, we argue that decision conflict (rather than the use of intuition vs. reflection) drives response times, leading to an inverted-U shaped relationship between RT and cooperation. Studies 1 through 3 show that intermediate decisions take longer than both extremely selfish and extremely cooperative decisions. Studies 4 and 5 find that the conflict between self-interested and cooperative motives explains individual differences in RTs. Manipulating conflictedness causes longer RTs and more intermediate decisions, and RTs mediate the relationship between conflict and intermediate decisions. Finally, Studies 6 and 7 demonstrate that conflict is distinct from reflection by manipulating the use of intuition (vs. reflection). Experimentally promoting reliance on intuition increases cooperation, but has no effects on decision extremity or feelings of conflictedness. In sum, we provide evidence that RTs should not be interpreted as a direct proxy for the use of intuitive or reflective processes, and dissociate the effects of conflict and reflection in social decision making. PMID:26413891

  4. Variance-reduced simulation of lattice discrete-time Markov chains with applications in reaction networks

    NASA Astrophysics Data System (ADS)

    Maginnis, P. A.; West, M.; Dullerud, G. E.

    2016-10-01

    We propose an algorithm to accelerate Monte Carlo simulation for a broad class of stochastic processes. Specifically, the class of countable-state, discrete-time Markov chains driven by additive Poisson noise, or lattice discrete-time Markov chains. In particular, this class includes simulation of reaction networks via the tau-leaping algorithm. To produce the speedup, we simulate pairs of fair-draw trajectories that are negatively correlated. Thus, when averaged, these paths produce an unbiased Monte Carlo estimator that has reduced variance and, therefore, reduced error. Numerical results for three example systems included in this work demonstrate two to four orders of magnitude reduction of mean-square error. The numerical examples were chosen to illustrate different application areas and levels of system complexity. The areas are: gene expression (affine state-dependent rates), aerosol particle coagulation with emission and human immunodeficiency virus infection (both with nonlinear state-dependent rates). Our algorithm views the system dynamics as a "black-box", i.e., we only require control of pseudorandom number generator inputs. As a result, typical codes can be retrofitted with our algorithm using only minor changes. We prove several analytical results. Among these, we characterize the relationship of covariances between paths in the general nonlinear state-dependent intensity rates case, and we prove variance reduction of mean estimators in the special case of affine intensity rates.

  5. Release the BEESTS: Bayesian Estimation of Ex-Gaussian STop-Signal reaction time distributions.

    PubMed

    Matzke, Dora; Love, Jonathon; Wiecki, Thomas V; Brown, Scott D; Logan, Gordon D; Wagenmakers, Eric-Jan

    2013-01-01

    The stop-signal paradigm is frequently used to study response inhibition. In this paradigm, participants perform a two-choice response time (RT) task where the primary task is occasionally interrupted by a stop-signal that prompts participants to withhold their response. The primary goal is to estimate the latency of the unobservable stop response (stop signal reaction time or SSRT). Recently, Matzke et al. (2013) have developed a Bayesian parametric approach (BPA) that allows for the estimation of the entire distribution of SSRTs. The BPA assumes that SSRTs are ex-Gaussian distributed and uses Markov chain Monte Carlo sampling to estimate the parameters of the SSRT distribution. Here we present an efficient and user-friendly software implementation of the BPA-BEESTS-that can be applied to individual as well as hierarchical stop-signal data. BEESTS comes with an easy-to-use graphical user interface and provides users with summary statistics of the posterior distribution of the parameters as well various diagnostic tools to assess the quality of the parameter estimates. The software is open source and runs on Windows and OS X operating systems. In sum, BEESTS allows experimental and clinical psychologists to estimate entire distributions of SSRTs and hence facilitates the more rigorous analysis of stop-signal data. PMID:24339819

  6. Effects of contrast, spatial frequency, and stimulus duration on reaction time in rats.

    PubMed

    Kurylo, Daniel D; Chung, Caroline; Yeturo, Sowmya; Lanza, Joseph; Gorskaya, Arina; Bukhari, Farhan

    2015-01-01

    Early visual processing in rats is mediated by several pre-cortical pathways as well as multiple retinal ganglion cell types that vary in response characteristics. Discrete processing is thereby optimized for select ranges of stimulus parameters. In order to explore variation in response characteristics at a perceptual level, visual detection in rats was measured across a range of contrasts, spatial frequencies, and durations. Rats responded to the onset of Gabor patches. Onset time occurred after a random delay, and reaction time (RT) frequency distribution served to index target visibility. It was found that lower spatial frequency produced shorter RTs, as well as increased RT equivalent of contrast gain. Brief stimulus presentation reduced target visibility, slowed RTs, and reduced contrast gain at higher spatial frequencies. However, brief stimuli shortened RTs at low contrasts and low spatial frequencies, suggesting transient stimuli are more efficiently processed under these conditions. Collectively, perceptual characteristics appear to reflect distinctions in neural responses at early stages of processing. The RT characteristics found here may thereby reflect the contribution of multiple channels, and suggest a progressive shift in relative involvement across parameter levels.

  7. Thermodynamical properties of reaction intermediates during apoplastocyanin folding in time domain

    NASA Astrophysics Data System (ADS)

    Baden, N.; Hirota, S.; Takabe, T.; Funasaki, N.; Terazima, M.

    2007-11-01

    Two intermediates observed for the folding process of apoplastocyanin (apoPC) were investigated by using a photoinduced triggering system combined with the transient grating and transient lens methods. The thermodynamic quantities, enthalpy, heat capacity, partial volume, and thermal expansion volume changes during the protein folding reaction were measured in time domain for the first time. An interesting observation is the positive enthalpy changes during the folding process. This positive enthalpy change must be compensated by positive entropy changes, which could be originated from the dehydration effect of hydrophobic residues and/or the translational entropy gain of bulk water molecules. Observed negative heat capacity change was explained by the dehydration effect of hydrophilic residues and/or motional confinement of amino acid side chains and water molecules in apoPC. The signs of the volume change and thermal expansion volume were different for two processes and these changes were interpreted in terms of the different relative contributions of the hydration and the dehydration of the hydrophilic residues. These results indicated two-step hydrophobic collapses in the early stage of the apoPC folding, but the nature of the dynamics was different.

  8. Fast but not intuitive, slow but not reflective: Decision conflict drives reaction times in social dilemmas.

    PubMed

    Evans, Anthony M; Dillon, Kyle D; Rand, David G

    2015-10-01

    When people have the chance to help others at a cost to themselves, are cooperative decisions driven by intuition or reflection? To answer this question, recent studies have tested the relationship between reaction times (RTs) and cooperation, reporting both positive and negative correlations. To reconcile this apparent contradiction, we argue that decision conflict (rather than the use of intuition vs. reflection) drives response times, leading to an inverted-U shaped relationship between RT and cooperation. Studies 1 through 3 show that intermediate decisions take longer than both extremely selfish and extremely cooperative decisions. Studies 4 and 5 find that the conflict between self-interested and cooperative motives explains individual differences in RTs. Manipulating conflictedness causes longer RTs and more intermediate decisions, and RTs mediate the relationship between conflict and intermediate decisions. Finally, Studies 6 and 7 demonstrate that conflict is distinct from reflection by manipulating the use of intuition (vs. reflection). Experimentally promoting reliance on intuition increases cooperation, but has no effects on decision extremity or feelings of conflictedness. In sum, we provide evidence that RTs should not be interpreted as a direct proxy for the use of intuitive or reflective processes, and dissociate the effects of conflict and reflection in social decision making.

  9. Reaction time-related activity reflecting periodic, task-specific cognitive control.

    PubMed

    Barber, Anita D; Pekar, James J; Mostofsky, Stewart H

    2016-01-01

    Reaction time (RT) is associated with increased amplitude of the Blood Oxygen-Level Dependent (BOLD) response in cognitive control regions. The current study examined whether the Primary Condition (PC) effect and RT-BOLD effect both reflect the same cognitive control processes. In addition, RT-BOLD effects were examined in two Go/No-go tasks with different demands to determine whether RT-related activity is task-dependent, reflecting the recruitment of task-specific cognitive processes. Data simulations showed that RT-related activity could be distinguished from that of the primary condition if it is mean-centered. In that case, RT-related activity reflects periodically-engaged processes rather than "time-on-task" (ToT). RT-related activity was mostly distinct from that of the primary Go contrast, particularly for the perceptual decision task. Therefore, RT effects can reflect additional cognitive processes that are not captured by the PC contrast consistent with a periodic-engagement account. RT-BOLD effects occurred in a separate set of regions for the two tasks. For the task requiring a perceptual decision, RT-related activity occurred within occipital and posterior parietal regions supporting visual attention. For the task requiring a working memory decision, RT-related activity occurred within fronto-parietal regions supporting the maintenance and retrieval of task representations. The findings suggest that RT-related activity reflects task-specific processes that are periodically-engaged, particularly during less demanding tasks. PMID:26318935

  10. A real-time reverse transcriptase polymerase chain reaction for detection and quantification of Vesiculovirus

    PubMed Central

    Tolardo, Aline Lavado; de Souza, William Marciel; Romeiro, Marilia Farignoli; Vieira, Luiz Carlos; Luna, Luciano Kleber de Souza; Henriques, Dyana Alves; de Araujo, Jansen; Siqueira, Carlos Eduardo Hassegawa; Colombo, Tatiana Elias; Aquino, Victor Hugo; da Fonseca, Benedito Antonio Lopes; Bronzoni, Roberta Vieira de Morais; Nogueira, Maurício Lacerda; Durigon, Edison Luiz; Figueiredo, Luiz Tadeu Moraes

    2016-01-01

    Vesiculoviruses (VSV) are zoonotic viruses that cause vesicular stomatitis disease in cattle, horses and pigs, as well as sporadic human cases of acute febrile illness. Therefore, diagnosis of VSV infections by reliable laboratory techniques is important to allow a proper case management and implementation of strategies for the containment of virus spread. We show here a sensitive and reproducible real-time reverse transcriptase polymerase chain reaction (RT-PCR) for detection and quantification of VSV. The assay was evaluated with arthropods and serum samples obtained from horses, cattle and patients with acute febrile disease. The real-time RT-PCR amplified the Piry, Carajas, Alagoas and Indiana Vesiculovirus at a melting temperature 81.02 ± 0.8ºC, and the sensitivity of assay was estimated in 10 RNA copies/mL to the Piry Vesiculovirus. The viral genome has been detected in samples of horses and cattle, but not detected in human sera or arthropods. Thus, this assay allows a preliminary differential diagnosis of VSV infections. PMID:27276185

  11. Quantitative analysis of periodontal pathogens by ELISA and real-time polymerase chain reaction.

    PubMed

    Hamlet, Stephen M

    2010-01-01

    The development of analytical methods enabling the accurate identification and enumeration of bacterial species colonizing the oral cavity has led to the identification of a small number of bacterial pathogens that are major factors in the etiology of periodontal disease. Further, these methods also underpin more recent epidemiological analyses of the impact of periodontal disease on general health. Given the complex milieu of over 700 species of microorganisms known to exist within the complex biofilms found in the oral cavity, the identification and enumeration of oral periodontopathogens has not been an easy task. In recent years however, some of the intrinsic limitations of the more traditional microbiological analyses previously used have been overcome with the advent of immunological and molecular analytical methods. Of the plethora of methodologies reported in the literature, the enzyme-linked immunosorbent assay (ELISA), which combines the specificity of antibody with the sensitivity of simple enzyme assays and the polymerase chain reaction (PCR), has been widely utilized in both laboratory and clinical applications. Although conventional PCR does not allow quantitation of the target organism, real-time PCR (rtPCR) has the ability to detect amplicons as they accumulate in "real time" allowing subsequent quantitation. These methods enable the accurate quantitation of as few as 10(2) (using rtPCR) to 10(4) (using ELISA) periodontopathogens in dental plaque samples.

  12. Reaction time to threat stimuli in panic disorder and social phobia.

    PubMed

    Cloitre, M; Heimberg, R G; Holt, C S; Liebowitz, M R

    1992-11-01

    Two studies assessed response time among clinically anxious subjects and normal controls when presented with threat, positive and neutral stimuli under perceptual (lexical decision) and semantic (category decision) task conditions. In Study 1, panic disorder subjects' (n = 14) performance was compared to that of matched normal controls (n = 14) while in Study 2 social phobic subjects (n = 24) were compared to matched normal controls (n = 24). Relative to matched normal controls, panic disorder subjects but not social phobics tended to show greater slowing in performance on the more cognitively complex (category) task. A second finding, consistent across both studies was that, compared to the normal control groups, both panic and social phobic groups showed significantly slowed responses to threat words in both the perceptual and semantic tasks. Such findings are directly counter to the predictions of a mood congruence hypothesis. This apparent contradiction is resolved by a review of the literature which indicates that mood-related facilitation effects are obtained only in tasks which tap awareness of threat information rather than speed of response. It is suggested that while anxiety may produce enhanced awareness of threat, it may inhibit responsiveness to it. The results of these studies are seen as consistent with ethological theories of inhibited motoric responses under certain threat conditions. Furthermore, the findings suggest that caution is indicated in interpreting slowed reaction time to threat stimuli in tasks such as the Stroop color naming task as purely the result of attentional processes. PMID:1417686

  13. The main factor causing prolonged reaction time on force producing process following anterior cruciate ligament reconstruction.

    PubMed

    Kaneko, F; Onari, K; Kawaguchi, K; Tsukisaka, K

    2000-12-01

    This study investigated the electromechanical properties of atrophied human quadriceps femoris muscle during a voluntarily elicited maximal isometric contraction (MVC) and a peripherally stimulated twitch contraction. Nineteen patients were recruited 2-3 months following a unilateral anterior cruciate ligament (ACL) reconstruction. Both the involved leg as well as the uninvolved leg were studied. Maximal twitch response was elicited and surface electromyograms (EMG) were recorded from the vastus lateralis. Total reaction time (TRT) for both MVC and twitch on involved leg was prolonged (251.47 msec, 26.01 msec). This prolongation suggests an extended lag in avoiding injury such as during sports. Pre-motor time during both MVC and twitch (PMTmvc, PMTtwitch) did not differ between both groups. Electromechanical delay during MVC (EMDmvc) was prolonged on involved leg (53.42 msec), and also evoked twitch EMD (EMDtwitch) (20.04 msec) as compared to the opposite side. Prolonged EMDtwitch may be due to a decrease in stiffness of the series elastic component, changes of peripheral muscle composition to containing more slow type muscle fibers, or a decrease in function of the excitation-contraction (E-C) coupling process. A prolonged EMDtwitch can also explain the prolonged EMDmvc. These findings also suggested that prolonged TRTmvc to visual stimulus during MVC in atrophied human quadriceps femoris muscle after disuse was principally due to prolongation of EMDmvc. Prolonged EMDmvc may have resulted from decreased muscle stiffness, which was evident in the prolongation of the EMDtwitch.

  14. Trends and advances in food analysis by real-time polymerase chain reaction.

    PubMed

    Salihah, Nur Thaqifah; Hossain, Mohammad Mosharraf; Lubis, Hamadah; Ahmed, Minhaz Uddin

    2016-05-01

    Analyses to ensure food safety and quality are more relevant now because of rapid changes in the quantity, diversity and mobility of food. Food-contamination must be determined to maintain health and up-hold laws, as well as for ethical and cultural concerns. Real-time polymerase chain reaction (RT-PCR), a rapid and inexpensive quantitative method to detect the presence of targeted DNA-segments in samples, helps in determining both accidental and intentional adulterations of foods by biological contaminants. This review presents recent developments in theory, techniques, and applications of RT-PCR in food analyses, RT-PCR addresses the limitations of traditional food analyses in terms of sensitivity, range of analytes, multiplexing ability, cost, time, and point-of-care applications. A range of targets, including species of plants or animals which are used as food ingredients, food-borne bacteria or viruses, genetically modified organisms, and allergens, even in highly processed foods can be identified by RT-PCR, even at very low concentrations. Microfluidic RT-PCR eliminates the separate sample-processing step to create opportunities for point-of-care analyses. We also cover the challenges related to using RT-PCR for food analyses, such as the need to further improve sample handling.

  15. Positive and negative stimuli in relation to tennis players' reaction time.

    PubMed

    Mead, T P; Drowatzky, J N; Hardin-Crosby, L

    2000-02-01

    Research has indicated that negative and positive thoughts may affect sport performance. The purpose of this analogue study was to assess whether negative and positive stimuli influenced tennis performance similar to positive and negative thought. The reaction time (RT) of 40 competitive tennis players was measured during a timed response to a tennis ball rotating in a topspin, sidespin, or backspin direction on the computer screen. Immediately prior to the ball presentation, a phrase (accessory stimulus) was presented visually or aurally. The accessory stimulus provided either positive (e.g., 'nice shot') or negative information (e.g., 'bad shot') followed by the subject's name. Analysis showed a main effect only for the type of spin. The slowest RT occurred when responding to a tennis ball rotating in a backspin direction. A significant interaction was found for the sensory modality (audition vs vision) and polarity (positive vs negative) of the accessory stimulus. RT to negative stimuli was slowest when the accessory stimulus was presented aurally. The quickest RT to positive stimuli occurred when the accessory stimulus was presented aurally. These results indicated that negative and positive stimuli, when presented aurally, affected performance as positive and negative thoughts measured in other studies. Not measured was whether negative and positive stimuli actually produce the negative and positive thoughts, respectively, that have been reported to affect performance. PMID:10769904

  16. Trends and advances in food analysis by real-time polymerase chain reaction.

    PubMed

    Salihah, Nur Thaqifah; Hossain, Mohammad Mosharraf; Lubis, Hamadah; Ahmed, Minhaz Uddin

    2016-05-01

    Analyses to ensure food safety and quality are more relevant now because of rapid changes in the quantity, diversity and mobility of food. Food-contamination must be determined to maintain health and up-hold laws, as well as for ethical and cultural concerns. Real-time polymerase chain reaction (RT-PCR), a rapid and inexpensive quantitative method to detect the presence of targeted DNA-segments in samples, helps in determining both accidental and intentional adulterations of foods by biological contaminants. This review presents recent developments in theory, techniques, and applications of RT-PCR in food analyses, RT-PCR addresses the limitations of traditional food analyses in terms of sensitivity, range of analytes, multiplexing ability, cost, time, and point-of-care applications. A range of targets, including species of plants or animals which are used as food ingredients, food-borne bacteria or viruses, genetically modified organisms, and allergens, even in highly processed foods can be identified by RT-PCR, even at very low concentrations. Microfluidic RT-PCR eliminates the separate sample-processing step to create opportunities for point-of-care analyses. We also cover the challenges related to using RT-PCR for food analyses, such as the need to further improve sample handling. PMID:27407185

  17. [Examination of frontal lobe function of Parkinson disease patients using Stroop reaction time].

    PubMed

    Shirahama, Kunji; Kaseda, Yumiko; Mimori, Yasuyo; Kobayashi, Ryuji

    2006-11-01

    The purpose of this study is to examine frontal lobe function of non-dementia Parkinson's disease (PD) patients. We examined the neuropsychological and behavioral evaluation (Stroop reaction time: SRT). Target image (20%) and non-target image (80%) were presented to PD patients, healthy elderly controls, and healthy young subjects at random. We instructed subjects that the button should pressed on the target image. This study was designed to investigate the mental set under three conditions. The Stroop test, Word Fluency Test (WFT), and Geriatric Depression Scale (GDS) were used to assess cognitive function. The SRT of PD were congruent condition and incongruent condition increased compared with simple condition. The delay of a similar SRT was seen in the healthy elderly control and young groups. However, the SRT of PD patients was slower under incongruent condition than under congruent condition. It appears that PD spent time on judgment in under incongruent condition because the meaning of the character did not correspond to the color of the character. Because, there were no significant between PD and healthy elderly subjects in Stroop test, WFT, and GDS, frontal lobe function had a partial deficit. The SRT of PD was increased by the partial deficit in information processing ability in addition to movement dysfunction.

  18. Free-running circadian rhythms of muscle strength, reaction time, and body temperature in totally blind people.

    PubMed

    Squarcini, Camila Fabiana Rossi; Pires, Maria Laura Nogueira; Lopes, Cleide; Benedito-Silva, Ana Amélia; Esteves, Andrea Maculano; Cornelissen-Guillaume, Germaine; Matarazzo, Carolina; Garcia, Danilo; da Silva, Maria Stella Peccin; Tufik, Sergio; de Mello, Marco Túlio

    2013-01-01

    Light is the major synchronizer of circadian rhythms. In the absence of light, as for totally blind people, some variables, such as body temperature, have an endogenous period that is longer than 24 h and tend to be free running. However, the circadian rhythm of muscle strength and reaction time in totally blind people has not been defined in the literature. The objective of this study was to determine the period of the endogenous circadian rhythm of the isometric and isokinetic contraction strength and simple reaction time of totally blind people. The study included six totally blind people with free-running circadian rhythms and four sighted people (control group). Although the control group required only a single session to determine the circadian rhythm, the blind people required three sessions to determine the endogenous period. In each session, isometric strength, isokinetic strength, reaction time, and body temperature were collected six different times a day with an interval of at least 8 h. The control group had better performance for strength and reaction time in the afternoon. For the blind, this performance became delayed throughout the day. Therefore, we conclude that the circadian rhythms of strength and simple reaction time of totally blind people are within their free-running periods. For some professionals, like the blind paralympic athletes, activities that require large physiological capacities in which the maximum stimulus should match the ideal time of competition may result in the blind athletes falling short of their expected performance under this free-running condition.

  19. Accessing world knowledge: evidence from N400 and reaction time priming.

    PubMed

    Chwilla, Dorothee J; Kolk, Herman H J

    2005-12-01

    How fast are we in accessing world knowledge? In two experiments, we tested for priming for word triplets that described a conceptual script (e.g., DIRECTOR-BRIBE-DISMISSAL) but were not associatively related and did not share a category relationship. Event-related brain potentials were used to track the time course at which script information becomes available. In Experiment 1, in which participants made lexical decisions, we found a facilitation for script-related relative to unrelated triplets, as indicated by (i) a decrease in both reaction time and errors, and (ii) an N400-like priming effect. In Experiment 2, we further explored the locus of script priming by increasing the contribution of meaning integration processes. The participants' task was to indicate whether the three words presented a plausible scenario. Again, an N400 script priming effect was obtained. Directing attention to script relations was effective in enhancing the N400 effect. The time course of the N400 effect was similar to that of the standard N400 effect to semantic relations. The present results show that script priming can be obtained in the visual modality, and that script information is immediately accessed and integrated with context. This supports the view that script information forms a central aspect of word meaning. The RT and N400 script priming effects reported in this article are problematic for most current semantic priming models, like spreading activation models, expectancy models, and task-specific semantic matching/integration models. They support a view in which there is no clear cutoff point between semantic knowledge and world knowledge. PMID:16202570

  20. Semen characteristics and reaction time of Yankasa rams experimentally infected with Trypanosoma evansi infection.

    PubMed

    Ogundele, Francis Abidemi; Okubanjo, Oluyinka Oluseyi; Ajanusi, Olagunju Joseph; Fadason, Samuel Tanko

    2016-08-01

    Trypanosomosis is a serious, often fatal disease of domestic animals and humans, and a major constraint to livestock productivity and agricultural development in areas of Africa, Latin America, the Middle East, and Asia. It is caused by hemoflagelate protozoan of the genus Trypanosoma. Several species of Trypanosoma such as Trypanosoma congolense, Trypanosoma vivax, Trypanosoma brucei, and Trypanosoma evansi are known to infect domestic animals. Trypanosoma evansi is one of the most widespread pathogenic trypanosomes in the world causing disease known as "Surra" in animals. The effects of experimental T evansi infection on some aspects of reproduction in Yankasa rams were investigated over a 108-day period. Rams in the infected group A (n = 7) were each inoculated with 1 × 10(6) trypanosomes in 1 mL of donor blood via the jugular vein, whereas the control group B (n = 5) were administered 1 mL of normal saline. Semen volume, gross motility, live and/or dead sperm ratio, sperm morphologic abnormalities, and concentration as well as reaction time of infected and control rams were evaluated on a weekly basis. The results showed a nonsignificant (P > 0.05) decrease in semen volume and a significant (P < 0.05) decrease in concentration compared to the control rams. Reaction time showed considerable significant (P < 0.05) increase from preinfection values 26.7 ± 4.54 to 94.7 ± 7.54 seconds compared to control 32.9 ± 2.64 to 33.4 ± 4.78 seconds. Furthermore, semen gross motility for infected rams differed significantly (P < 0.05) from those of the control. There was a significant surge (P < 0.05) in the total sperm morphologic abnormalities in the infected rams to 90.75 ± 2.73% by week 20 (14 weeks after infection), compared to preinfection value of 20.9 ± 0.52%. The outcome of this study suggests that infection with T evansi in Yankasa rams has far reaching severe effects on their reproductive performance.

  1. Semen characteristics and reaction time of Yankasa rams experimentally infected with Trypanosoma evansi infection.

    PubMed

    Ogundele, Francis Abidemi; Okubanjo, Oluyinka Oluseyi; Ajanusi, Olagunju Joseph; Fadason, Samuel Tanko

    2016-08-01

    Trypanosomosis is a serious, often fatal disease of domestic animals and humans, and a major constraint to livestock productivity and agricultural development in areas of Africa, Latin America, the Middle East, and Asia. It is caused by hemoflagelate protozoan of the genus Trypanosoma. Several species of Trypanosoma such as Trypanosoma congolense, Trypanosoma vivax, Trypanosoma brucei, and Trypanosoma evansi are known to infect domestic animals. Trypanosoma evansi is one of the most widespread pathogenic trypanosomes in the world causing disease known as "Surra" in animals. The effects of experimental T evansi infection on some aspects of reproduction in Yankasa rams were investigated over a 108-day period. Rams in the infected group A (n = 7) were each inoculated with 1 × 10(6) trypanosomes in 1 mL of donor blood via the jugular vein, whereas the control group B (n = 5) were administered 1 mL of normal saline. Semen volume, gross motility, live and/or dead sperm ratio, sperm morphologic abnormalities, and concentration as well as reaction time of infected and control rams were evaluated on a weekly basis. The results showed a nonsignificant (P > 0.05) decrease in semen volume and a significant (P < 0.05) decrease in concentration compared to the control rams. Reaction time showed considerable significant (P < 0.05) increase from preinfection values 26.7 ± 4.54 to 94.7 ± 7.54 seconds compared to control 32.9 ± 2.64 to 33.4 ± 4.78 seconds. Furthermore, semen gross motility for infected rams differed significantly (P < 0.05) from those of the control. There was a significant surge (P < 0.05) in the total sperm morphologic abnormalities in the infected rams to 90.75 ± 2.73% by week 20 (14 weeks after infection), compared to preinfection value of 20.9 ± 0.52%. The outcome of this study suggests that infection with T evansi in Yankasa rams has far reaching severe effects on their reproductive performance. PMID:27188633

  2. Placing Inspection Time, Reaction Time, and Perceptual Speed in the Broader Context of Cognitive Ability: The VPR Model in the Lothian Birth Cohort 1936

    ERIC Educational Resources Information Center

    Johnson, Wendy; Deary, Ian J.

    2011-01-01

    The idea that information processing speed is related to cognitive ability has a long history. Much evidence has been amassed in its support, with respect to both individual differences in general intelligence and developmental trajectories. Two so-called elementary cognitive tasks, reaction time and inspection time, have been used to compile this…

  3. In situ and real-time monitoring of mechanochemical milling reactions using synchrotron X-ray diffraction.

    PubMed

    Halasz, Ivan; Kimber, Simon A J; Beldon, Patrick J; Belenguer, Ana M; Adams, Frank; Honkimäki, Veijo; Nightingale, Richard C; Dinnebier, Robert E; Friščić, Tomislav

    2013-09-01

    We describe the only currently available protocol for in situ, real-time monitoring of mechanochemical reactions and intermediates by X-ray powder diffraction. Although mechanochemical reactions (inducing transformations by mechanical forces such as grinding and milling) are normally performed in commercially available milling assemblies, such equipment does not permit direct reaction monitoring. We now describe the design and in-house modification of milling equipment that allows the reaction jars of the operating mill to be placed in the path of a high-energy (∼90 keV) synchrotron X-ray beam while the reaction is taking place. Resulting data are analyzed using conventional software, such as TOPAS. Reaction intermediates and products are identified using the Cambridge Structural Database or Inorganic Crystal Structure Database. Reactions are analyzed by fitting the time-resolved diffractograms using structureless Pawley refinement for crystalline phases that are not fully structurally characterized (such as porous frameworks with disordered guests), or the Rietveld method for solids with fully determined crystal structures (metal oxides, coordination polymers).

  4. Improvement of attention span and reaction time with hyperbaric oxygen treatment in patients with toxic injury due to mold exposure.

    PubMed

    Ezra, N; Dang, K; Heuser, G

    2011-01-01

    It is, by now, well established that mold toxins (mycotoxins) can cause significant adverse health effects. In this study, 15 subjects who developed an attention deficit disorder (ADD) and slowing of reaction time at the time of exposure to mold toxins were identified. Deficits in attention span and reaction time were documented not only by taking a careful history, but also by performing a Test of Variables of Attention (TOVA). The TOVA test provides an objective measure of these two variables. It was found that mold-exposed subjects show statistically significant decreases in attention span and significant increases in reaction time to stimuli compared to controls. After ten sessions of hyperbaric oxygen treatment (HBOT), a statistically significant improvement was seen in both measures. This preliminary study suggests promising outcomes in treating mold-exposed patients with hyperbaric oxygen.

  5. Stabilization strategies of a general nonlinear car-following model with varying reaction-time delay of the drivers.

    PubMed

    Li, Shukai; Yang, Lixing; Gao, Ziyou; Li, Keping

    2014-11-01

    In this paper, the stabilization strategies of a general nonlinear car-following model with reaction-time delay of the drivers are investigated. The reaction-time delay of the driver is time varying and bounded. By using the Lyapunov stability theory, the sufficient condition for the existence of the state feedback control strategy for the stability of the car-following model is given in the form of linear matrix inequality, under which the traffic jam can be well suppressed with respect to the varying reaction-time delay. Moreover, by considering the external disturbance for the running cars, the robust state feedback control strategy is designed, which ensures robust stability and a smaller prescribed H∞ disturbance attenuation level for the traffic flow. Numerical examples are given to illustrate the effectiveness of the proposed methods.

  6. Improvement of attention span and reaction time with hyperbaric oxygen treatment in patients with toxic injury due to mold exposure

    PubMed Central

    Ezra, N.; Dang, K.

    2010-01-01

    It is, by now, well established that mold toxins (mycotoxins) can cause significant adverse health effects. In this study, 15 subjects who developed an attention deficit disorder (ADD) and slowing of reaction time at the time of exposure to mold toxins were identified. Deficits in attention span and reaction time were documented not only by taking a careful history, but also by performing a Test of Variables of Attention (TOVA). The TOVA test provides an objective measure of these two variables. It was found that mold-exposed subjects show statistically significant decreases in attention span and significant increases in reaction time to stimuli compared to controls. After ten sessions of hyperbaric oxygen treatment (HBOT), a statistically significant improvement was seen in both measures. This preliminary study suggests promising outcomes in treating mold-exposed patients with hyperbaric oxygen. PMID:20978814

  7. The effect of oxygen on time-dependent bifurcations in the Belousov-Zhabotinsky oscillating chemical reaction in a batch.

    PubMed

    Kalishyn, Yevhen Yu; Rachwalska, Małgorzata; Khavrus, Vyacheslav O; Strizhak, Peter E

    2005-04-21

    We have studied the effect of oxygen on the time-dependent bifurcations of transient oscillations in the Belousov-Zhabotinsky oscillating chemical reaction in a closed system. Experiments show that oscillations disappear through different bifurcations depending on the oxygen concentration in gas phase above the reaction solution. Oscillations disappear through the time-delayed Hopf bifurcation at low oxygen concentrations, whereas at high oxygen concentrations they disappear through the time-dependent SNIPER (saddle-node infinite period) bifurcation. We propose a kinetic scheme that describes the effects observed in experiments. Good agreement between the experimental data and simulations is obtained.

  8. Fusion and neutron transfer reactions with weakly bound nuclei within time-dependent and coupled channel approaches

    NASA Astrophysics Data System (ADS)

    Samarin, V. V.

    2016-05-01

    The time-dependent Schrödinger equation and the coupled channel approach based on the method of perturbed stationary two-center states are used to describe nucleon transfers and fusion in low-energy nuclear reactions. Results of the cross sections calculation for the formation of the 198Au and fusion in the 6He+197Au reaction and for the formation of the 65Zn in 6He+64Zn reaction agree satisfactorily with the experimental data near the barrier. The Feynman's continual integrals calculations for a few-body systems were used for the proposal of the new form of the shell model mean field for helium isotopes.

  9. Choice reaction time to movement of eccentric visual targets during concurrent rotary acceleration

    NASA Technical Reports Server (NTRS)

    Hamerman, J. A.

    1979-01-01

    This study investigates the influence of concurrent rotary acceleration on choice reaction time (RT) to a small, accelerating visual cursor on a cathode-ray tube. Subjects sat in an enclosed rotating device at the center of rotation and observed a 3-mm dot accelerating at different rates across a cathode-ray tube. The dot was viewed at various eccentricities under conditions of visual stimulation alone and with concurrent rotary acceleration. Subjects responded to both vertical and horizontal dot movements. There was a significant inverse relationship between choice RT and level of dot acceleration (p less than .001), and a significant direct relationship between choice RT and eccentricity (p less than .001). There was no significant difference between choice RT to vertical or horizontal dot motion (p greater than .25), and choice RT was not significantly affected by concurrent rotary acceleration (p greater than .10). The results are discussed in terms of the effects of vestibular stimulation on choice RT to visual motion.

  10. Rethinking fast and slow based on a critique of reaction-time reverse inference

    PubMed Central

    Krajbich, Ian; Bartling, Björn; Hare, Todd; Fehr, Ernst

    2015-01-01

    Do people intuitively favour certain actions over others? In some dual-process research, reaction-time (RT) data have been used to infer that certain choices are intuitive. However, the use of behavioural or biological measures to infer mental function, popularly known as ‘reverse inference', is problematic because it does not take into account other sources of variability in the data, such as discriminability of the choice options. Here we use two example data sets obtained from value-based choice experiments to demonstrate that, after controlling for discriminability (that is, strength-of-preference), there is no evidence that one type of choice is systematically faster than the other. Moreover, using specific variations of a prominent value-based choice experiment, we are able to predictably replicate, eliminate or reverse previously reported correlations between RT and selfishness. Thus, our findings shed crucial light on the use of RT in inferring mental processes and strongly caution against using RT differences as evidence favouring dual-process accounts. PMID:26135809

  11. Polymerase chain reaction and real-time PCR for diagnosing of Leishmania infantum chagasi in dogs.

    PubMed

    Ramos, Rafael Antonio do Nascimento; Ramos, Carlos Alberto do Nascimento; Jusi, Márcia Mariza Gomes; de Araújo, Flábio Ribeiro; Machado, Rosangela Zacarias; Faustino, Maria Aparecida da Glória; Alves, Leucio Câmara

    2012-01-01

    The importance of dogs as a reservoir for Leishmania infantumchagasi in urban environments has stimulated numerous studies assessing diagnostic techniques. When performed properly, such procedures are an important step in preventing leishmaniasis in humans. Molecular methods have become prominent for this purpose. The aim of the present study was to determine the performance of the polymerase chain reaction (PCR) and real-time PCR (qPCR) for diagnosing of canine visceral leishmaniasis (CVL) using different biological samples. For this, 35 dogs from an area endemic for CVL were used. Bone marrow aspirate and lymph node and spleen fragments from these dogs were used for the molecular diagnosis. In the present study, qPCR was able to detect a greater number of positive animals than seen with PCR. Among the different biological samples used, there was no significant difference in L. infantumchagasi DNA detection between PCR and qPCR. However, considering that lymph nodes are easy to acquire, these can be considered to be the best samples for making molecular diagnoses of L. infantum chagasi infection.

  12. Single-trial prediction of reaction time variability from MEG brain activity.

    PubMed

    Ohata, Ryu; Ogawa, Kenji; Imamizu, Hiroshi

    2016-06-02

    Neural activity prior to movement onset contains essential information for predictive assistance for humans using brain-machine-interfaces (BMIs). Even though previous studies successfully predicted different goals for upcoming movements, it is unclear whether non-invasive recording signals contain the information to predict trial-by-trial behavioral variability under the same movement. In this paper, we examined the predictability of subsequent short or long reaction times (RTs) from magnetoencephalography (MEG) signals in a delayed-reach task. The difference in RTs was classified significantly above chance from 550 ms before the go-signal onset using the cortical currents in the premotor cortex. Significantly above-chance classification was performed in the lateral prefrontal and the right inferior parietal cortices at the late stage of the delay period. Thus, inter-trial variability in RTs is predictable information. Our study provides a proof-of-concept of the future development of non-invasive BMIs to prevent delayed movements.

  13. Single-trial prediction of reaction time variability from MEG brain activity

    PubMed Central

    Ohata, Ryu; Ogawa, Kenji; Imamizu, Hiroshi

    2016-01-01

    Neural activity prior to movement onset contains essential information for predictive assistance for humans using brain-machine-interfaces (BMIs). Even though previous studies successfully predicted different goals for upcoming movements, it is unclear whether non-invasive recording signals contain the information to predict trial-by-trial behavioral variability under the same movement. In this paper, we examined the predictability of subsequent short or long reaction times (RTs) from magnetoencephalography (MEG) signals in a delayed-reach task. The difference in RTs was classified significantly above chance from 550 ms before the go-signal onset using the cortical currents in the premotor cortex. Significantly above-chance classification was performed in the lateral prefrontal and the right inferior parietal cortices at the late stage of the delay period. Thus, inter-trial variability in RTs is predictable information. Our study provides a proof-of-concept of the future development of non-invasive BMIs to prevent delayed movements. PMID:27250872

  14. To transform or not to transform: using generalized linear mixed models to analyse reaction time data

    PubMed Central

    Lo, Steson; Andrews, Sally

    2015-01-01

    Linear mixed-effect models (LMMs) are being increasingly widely used in psychology to analyse multi-level research designs. This feature allows LMMs to address some of the problems identified by Speelman and McGann (2013) about the use of mean data, because they do not average across individual responses. However, recent guidelines for using LMM to analyse skewed reaction time (RT) data collected in many cognitive psychological studies recommend the application of non-linear transformations to satisfy assumptions of normality. Uncritical adoption of this recommendation has important theoretical implications which can yield misleading conclusions. For example, Balota et al. (2013) showed that analyses of raw RT produced additive effects of word frequency and stimulus quality on word identification, which conflicted with the interactive effects observed in analyses of transformed RT. Generalized linear mixed-effect models (GLMM) provide a solution to this problem by satisfying normality assumptions without the need for transformation. This allows differences between individuals to be properly assessed, using the metric most appropriate to the researcher's theoretical context. We outline the major theoretical decisions involved in specifying a GLMM, and illustrate them by reanalysing Balota et al.'s datasets. We then consider the broader benefits of using GLMM to investigate individual differences. PMID:26300841

  15. A quantitative real-time polymerase chain reaction assay for the seagrass pathogen Labyrinthula zosterae.

    PubMed

    Bergmann, Nina; Fricke, Birgit; Schmidt, Martina C; Tams, Verena; Beining, Katrin; Schwitte, Hildegard; Boettcher, Anne A; Martin, Daniel L; Bockelmann, Anna-Christina; Reusch, Thorsten B H; Rauch, Gisep

    2011-11-01

    The protist Labyrinthula zosterae (Phylum Bigyra, sensu Tsui et al. 2009) has been identified as a causative agent of wasting disease in eelgrass (Zostera marina), of which the most intense outbreak led to the destruction of 90% of eelgrass beds in eastern North America and western Europe in the 1930s. Outbreaks still occur today, albeit at a smaller scale. Traditionally, L. zosterae has been quantified by measuring the necrotic area of Z. marina leaf tissue. This indirect method can however only lead to a very rough estimate of pathogen load. Here, we present a quantitative real-time polymerase chain reaction (qPCR) approach to directly detect and quantify L. zosterae in eelgrass tissue. Based on the internal transcribed spacer (ITS) sequences of rRNA genes, species-specific primers were designed. Using our qPCR, we were able to quantify accurately and specifically L. zosterae load both from culture and eelgrass leaves using material from Europe and North America. Our detection limit was less than one L. zosterae cell. Our results demonstrate the potential of this qPCR assay to provide rapid, accurate and sensitive molecular identification and quantification of L. zosterae. In view of declining seagrass populations worldwide, this method will provide a valuable tool for seagrass ecologists and conservation projects. PMID:21777400

  16. Identification of four squid species by quantitative real-time polymerase chain reaction.

    PubMed

    Ye, Jian; Feng, Junli; Liu, Shasha; Zhang, Yanping; Jiang, Xiaona; Dai, Zhiyuan

    2016-02-01

    Squids are distributed worldwide, including many species of commercial importance, and they are often made into varieties of flavor foods. The rapid identification methods for squid species especially their processed products, however, have not been well developed. In this study, quantitative real-time PCR (qPCR) systems based on specific primers and TaqMan probes have been established for rapid and accurate identification of four common squid species (Ommastrephes bartramii, Dosidicus gigas, Illex argentinus, Todarodes pacificus) in Chinese domestic market. After analyzing mitochondrial genes reported in GenBank, the mitochondrial cytochrome b (Cytb) gene was selected for O. bartramii detection, cytochrome c oxidase subunit I (COI) gene for D. gigas and T. Pacificus detection, ATPase subunit 6 (ATPase 6) gene for I. Argentinus detection, and 12S ribosomal RNA (12S rDNA) gene for designing Ommastrephidae-specific primers and probe. As a result, all the TaqMan systems are of good performance, and efficiency of each reaction was calculated by making standard curves. This method could detect target species either in single or mixed squid specimen, and it was applied to identify 12 squid processed products successfully. Thus, it would play an important role in fulfilling labeling regulations and squid fishery control.

  17. Humic substances cause fluorescence inhibition in real-time polymerase chain reaction.

    PubMed

    Sidstedt, Maja; Jansson, Linda; Nilsson, Elin; Noppa, Laila; Forsman, Mats; Rådström, Peter; Hedman, Johannes

    2015-10-15

    Real-time polymerase chain reaction (qPCR) is the cornerstone of DNA analysis, enabling detection and quantification of minute nucleic acid amounts. However, PCR-based analysis is limited, in part, by the presence of inhibitors in the samples. PCR inhibition has been viewed solely as failure to efficiently generate amplicons, that is, amplification inhibition. Humic substances (HS) are well-known inhibitors of PCR amplification. Here we show that HS from environmental samples, specifically humic acid (HA), are very potent detection inhibitors, that is, quench the fluorescence signal of double-stranded DNA (dsDNA) binding dyes. HA quenched the fluorescence of the commonly used qPCR dyes EvaGreen, ResoLight, SYBR Green I, and SYTO 82, generating lowered amplification plots, although amplicon production was unaffected. For EvaGreen, 500 ng of HA quenched nearly all fluorescence, whereas 1000 ng of HA completely inhibited amplification when applying Immolase DNA polymerase with bovine serum albumin (BSA). Fluorescence spectroscopy measurements showed that HA quenching was either static or collisional and indicated that HA bound directly to the dye. Fulvic acid did not act as a qPCR detection inhibitor but inhibited amplification similarly to HA. Hydrolysis probe fluorescence was not quenched by HA. Detection inhibition is an overlooked phenomenon that needs to be considered to allow for development of optimal qPCR assays.

  18. Acute effects of exercise and active video games on adults' reaction time and perceived exertion.

    PubMed

    Guzmán, José F; López-García, Jesús

    2016-11-01

    The purpose of the present study was to examine the acute effects of resting, aerobic exercise practised alone, and aerobic exercise with active video games (AVG), on complex reaction time (CRT) and the post-exercise acute rate of perceived exertion (RPE) in young healthy adults. The experimental group was composed of 92 healthy young adults, 78 males and 13 females (age M = 21.9 ± 2.7 years) who completed two sessions, A and B. In session A, participants rode 30 min on an ergometer, while in session B they exercised for 30 min on an ergometer while playing an AVG on a Wii. The control group was composed of 30 young adults, 26 males and 4 females (age M = 21.4 ± 2.9 years) who rested for 30 min. In each session, a CRT task was performed before and after exercising or resting, and post-exercise global RPE was noted. Repeated measures general linear model (GLM) and Wilcoxon tests were performed. (1) Both aerobic exercise alone and aerobic exercise combined with AVG improved CRT, while resting did not; (2) aerobic exercise combined with AVG did not improve CRT more than aerobic exercise only; and (3) RPE was lower after aerobic exercise combined with AVG compared with aerobic exercise only. In young adults, exercise produces acute benefits on CRT, and practising exercise with AVG helps to decrease RPE.

  19. Acute effects of exercise and active video games on adults' reaction time and perceived exertion.

    PubMed

    Guzmán, José F; López-García, Jesús

    2016-11-01

    The purpose of the present study was to examine the acute effects of resting, aerobic exercise practised alone, and aerobic exercise with active video games (AVG), on complex reaction time (CRT) and the post-exercise acute rate of perceived exertion (RPE) in young healthy adults. The experimental group was composed of 92 healthy young adults, 78 males and 13 females (age M = 21.9 ± 2.7 years) who completed two sessions, A and B. In session A, participants rode 30 min on an ergometer, while in session B they exercised for 30 min on an ergometer while playing an AVG on a Wii. The control group was composed of 30 young adults, 26 males and 4 females (age M = 21.4 ± 2.9 years) who rested for 30 min. In each session, a CRT task was performed before and after exercising or resting, and post-exercise global RPE was noted. Repeated measures general linear model (GLM) and Wilcoxon tests were performed. (1) Both aerobic exercise alone and aerobic exercise combined with AVG improved CRT, while resting did not; (2) aerobic exercise combined with AVG did not improve CRT more than aerobic exercise only; and (3) RPE was lower after aerobic exercise combined with AVG compared with aerobic exercise only. In young adults, exercise produces acute benefits on CRT, and practising exercise with AVG helps to decrease RPE. PMID:27239681

  20. [Evoked potentials and vigilance states induced during the course of choice reaction time tests].

    PubMed

    Banquet, J P; Bourzeix, J C; Lesèvre, N

    1979-01-01

    Characteristics of Visual Evoked Potentials (N120, P200, P300) were investigated during choice reaction time situations in a group of 10 subjects practising meditation (E.S.) versus a matched control group (C.S.) During a series of visual stimuli occuring at fixed intervals, with 10% random omissions, the subjects were asked : 1) to respond by a finger displacement to each visual stimulus; 2) to hold on the response to the stimulus and to respond to omission. Both tasks were recorded before and after the practice of meditation or rest for the controls. The intergroup comparison showed that the experimental subjects had faster RT's with less mistakes, and N120 and P200 of larger amplitude and shorter latency. These differencies were significant before and after meditation. The transient effects of meditation or rest, were opposite for the two groups : whereas after meditation the RT's became longer with less mistakes, and the amplitude of P300 larger, after rest there was a decrease of the P300 amplitude and no change in the RT's of the controls. These results are interpreted in terms of selective attention capacity and information processing strategies, A.S.C. being used as a model for the study of these processes.

  1. Atomoxetine reduces anticipatory responding in a 5-choice serial reaction time task for adult zebrafish

    PubMed Central

    Parker, Matthew O.; Brock, Alistair J.; Sudwarts, Ari; Brennan, Caroline H.

    2014-01-01

    Deficits in impulse control are related to a number of psychiatric diagnoses, including attention deficit hyperactivity disorder, addiction, and pathological gambling. Despite increases in our knowledge about the underlying neurochemical and neuroanatomical correlates, understanding of the molecular and cellular mechanisms is less well established. Understanding these mechanisms is essential in order to move towards individualized treatment programs and increase efficacy of interventions. Zebrafish are a very useful vertebrate model for exploring molecular processes underlying disease owing to their small size and genetic tractability. Their utility in terms of behavioral neuroscience, however, hinges on the validation and publication of reliable assays with adequate translational relevance. Here, we report an initial pharmacological validation of a fully automated zebrafish version of the commonly used five-choice serial reaction time task using a variable interval pre-stimulus interval. We found that atomoxetine reduced anticipatory responses (0.6 mg/kg), whereas a high-dose (4 mg/kg) methylphenidate increased anticipatory responses and the number of trials completed in a session. On the basis of these results, we argue that similar neurochemical processes in fish as in mammals may control impulsivity, as operationally defined by anticipatory responses on a continuous performance task such as this, making zebrafish potentially a good model for exploring the molecular basis of impulse control disorders and for first-round drug screening. PMID:24481568

  2. Quantitative detection of Clostridium difficile in hospital environmental samples by real-time polymerase chain reaction.

    PubMed

    Mutters, R; Nonnenmacher, C; Susin, C; Albrecht, U; Kropatsch, R; Schumacher, S

    2009-01-01

    C. difficile-associated diarrhoea occurs commonly in hospitals and is a significant cause of morbidity and mortality. Hospital surfaces are often contaminated with nosocomial pathogens and may be responsible for cross-transmission, especially if hardy Gram-positive and spore-forming organisms are involved. The aim of this study was to quantify C. difficile in the hospital environment near C. difficile-positive and -negative patients using a quantitative real-time polymerase chain reaction. A total of 531 samples was collected from the clinical environment and classified into three groups according to patient and ward status for C. difficile. As expected, there were significantly higher counts of C. difficile on the floor and in the near environment of C. difficile patients. However, a significant correlation was found between C. difficile counts on the floor and on the hands of patients and healthcare workers (HCWs) in wards without evidence of C. difficile. This suggests that asymptomatic carriage among patients and HCWs can also contribute towards C. difficile transmission in hospitals. In conclusion, C. difficile can be transmitted via personal contact or via contaminated areas of the hospital environment.

  3. Real-time studies of battery electrochemical reactions inside a transmission electron microscope.

    SciTech Connect

    Leung, Kevin; Hudak, Nicholas S.; Liu, Yang; Liu, Xiaohua H.; Fan, Hongyou; Subramanian, Arunkumar; Shaw, Michael J.; Sullivan, John Patrick; Huang, Jian Yu

    2012-01-01

    We report the development of new experimental capabilities and ab initio modeling for real-time studies of Li-ion battery electrochemical reactions. We developed three capabilities for in-situ transmission electron microscopy (TEM) studies: a capability that uses a nanomanipulator inside the TEM to assemble electrochemical cells with ionic liquid or solid state electrolytes, a capability that uses on-chip assembly of battery components on to TEM-compatible multi-electrode arrays, and a capability that uses a TEM-compatible sealed electrochemical cell that we developed for performing in-situ TEM using volatile battery electrolytes. These capabilities were used to understand lithiation mechanisms in nanoscale battery materials, including SnO{sub 2}, Si, Ge, Al, ZnO, and MnO{sub 2}. The modeling approaches used ab initio molecular dynamics to understand early stages of ethylene carbonate reduction on lithiated-graphite and lithium surfaces and constrained density functional theory to understand ethylene carbonate reduction on passivated electrode surfaces.

  4. Identification of five highly priced tuna species by quantitative real-time polymerase chain reaction.

    PubMed

    Liu, Shasha; Xu, Kunhua; Wu, Zhigang; Xie, Xiao; Feng, Junli

    2016-09-01

    Tunas are economically important fishery worldwide, and are often used for commercial processed production. For effective fishery management and protection of consumers' rights, it is important to develop a molecular method to identify species in canned tuna products rapidly and reliably. Here, we have developed a duplex quantitative real-time PCR (qPCR) for identification of five highly priced tuna species (Thunnus maccoyii, Thunnus obesus, Thunnus albacares, Thunnus alalunga and Katsuwonus pelamis) from processed as well as fresh fish. After amplification and sequencing of seven genetic markers commonly used for species identification, 16S rDNA and control region (CR) of mitochondrial DNA were selected as the reference gene markers for genus Thunnus and tuna species identification, respectively. Subsequently, a 73 bp fragment of 16S rDNA and 85-99 bp fragment of CR were simultaneously amplified from each target species by qPCR. The qPCR efficiency of each reaction was calculated according to the standard curves, and the method was validated by amplification DNA extracted from single or mixed tuna specimen. The developed duplex qPCR system was applied to authenticate species of 14 commercial tuna products successfully, which demonstrated it was really a useful and academic technique to identify highly priced tuna species. PMID:25714139

  5. Single-trial prediction of reaction time variability from MEG brain activity.

    PubMed

    Ohata, Ryu; Ogawa, Kenji; Imamizu, Hiroshi

    2016-01-01

    Neural activity prior to movement onset contains essential information for predictive assistance for humans using brain-machine-interfaces (BMIs). Even though previous studies successfully predicted different goals for upcoming movements, it is unclear whether non-invasive recording signals contain the information to predict trial-by-trial behavioral variability under the same movement. In this paper, we examined the predictability of subsequent short or long reaction times (RTs) from magnetoencephalography (MEG) signals in a delayed-reach task. The difference in RTs was classified significantly above chance from 550 ms before the go-signal onset using the cortical currents in the premotor cortex. Significantly above-chance classification was performed in the lateral prefrontal and the right inferior parietal cortices at the late stage of the delay period. Thus, inter-trial variability in RTs is predictable information. Our study provides a proof-of-concept of the future development of non-invasive BMIs to prevent delayed movements. PMID:27250872

  6. Intraindividual Variability in Basic Reaction Time Predicts Middle-Aged and Older Pilots’ Flight Simulator Performance

    PubMed Central

    2013-01-01

    Objectives. Intraindividual variability (IIV) is negatively associated with cognitive test performance and is positively associated with age and some neurological disorders. We aimed to extend these findings to a real-world task, flight simulator performance. We hypothesized that IIV predicts poorer initial flight performance and increased rate of decline in performance among middle-aged and older pilots. Method. Two-hundred and thirty-six pilots (40–69 years) completed annual assessments comprising a cognitive battery and two 75-min simulated flights in a flight simulator. Basic and complex IIV composite variables were created from measures of basic reaction time and shifting and divided attention tasks. Flight simulator performance was characterized by an overall summary score and scores on communication, emergencies, approach, and traffic avoidance components. Results. Although basic IIV did not predict rate of decline in flight performance, it had a negative association with initial performance for most flight measures. After taking into account processing speed, basic IIV explained an additional 8%–12% of the negative age effect on initial flight performance. Discussion. IIV plays an important role in real-world tasks and is another aspect of cognition that underlies age-related differences in cognitive performance. PMID:23052365

  7. Determination of SFC, FFA, and equivalent reaction time for enzymatically interestified oils using NIRS.

    PubMed

    Houmøller, Lars P; Kristensen, Dorthe; Rosager, Helle

    2007-02-15

    The use of near infrared spectroscopy (NIRS) for rapid determination of the degree of interesterification of blends of palm stearin, coconut oil, and rapeseed oil obtained using an immobilized Thermomyces lanuginosa lipase at 70 degrees C was investigated. Interesterification was carried out by applying both fixed bed and batch reactors. Calibrations were developed for quantitative determination of solid fat content (SFC) at 10, 20, 30, 35, and 40 degrees C and free fatty acid (FFA) resulting in root mean square errors of prediction of 1.0, 1.3, 1.4, 1.6, 1.7, and 0.19% (w/w), respectively. The data showed that NIRS could be used to replace the traditional methods for determining FFA and SFC in vegetable oils. It was possible to monitor the activity of the immobilized enzyme for interesterification of margarine oils by predicting the equivalent reaction time in a batch reactor from NIR spectra. Root mean square errors of prediction for two different oil blends interesterified for 300 and 170min were 21 and 12min, respectively. PMID:19071387

  8. Gene Profiling Studies in Skeletal Muscle by Quantitative Real-Time Polymerase Chain Reaction Assay

    PubMed Central

    Bhatnagar, Shephali; Panguluri, Siva K.; Kumar, Ashok

    2012-01-01

    Summary Gene profiling is an excellent tool to identify the genetic mechanisms, networks, and molecular pathways involved in skeletal muscle development and muscular disorders. Oligonucleotide or cDNA microarray can be the first step to identify the global gene expression in the study of interest. As microarray techniques provide a large set of differentially expressed genes in a given comparison, the expression profile can be narrowed down by taking various parameters into consideration such as fold values, p-values, and their relevance to the study. Every technique has its own limitations. Therefore, further validation of the results with a different technique is always necessary. Quantitative real-time reverse-transcriptase polymerase chain reaction (qRT-PCR) is the most common technique to validate microarray data and to study the relative expression of specific genes in any experimental set-up. Here, we describe, the qRT-PCR technique, in detail, for -successful gene expression studies in skeletal muscle cells and tissues. PMID:22130845

  9. Atomoxetine reduces anticipatory responding in a 5-choice serial reaction time task for adult zebrafish.

    PubMed

    Parker, Matthew O; Brock, Alistair J; Sudwarts, Ari; Brennan, Caroline H

    2014-07-01

    Deficits in impulse control are related to a number of psychiatric diagnoses, including attention deficit hyperactivity disorder, addiction, and pathological gambling. Despite increases in our knowledge about the underlying neurochemical and neuroanatomical correlates, understanding of the molecular and cellular mechanisms is less well established. Understanding these mechanisms is essential in order to move towards individualized treatment programs and increase efficacy of interventions. Zebrafish are a very useful vertebrate model for exploring molecular processes underlying disease owing to their small size and genetic tractability. Their utility in terms of behavioral neuroscience, however, hinges on the validation and publication of reliable assays with adequate translational relevance. Here, we report an initial pharmacological validation of a fully automated zebrafish version of the commonly used five-choice serial reaction time task using a variable interval pre-stimulus interval. We found that atomoxetine reduced anticipatory responses (0.6 mg/kg), whereas a high-dose (4 mg/kg) methylphenidate increased anticipatory responses and the number of trials completed in a session. On the basis of these results, we argue that similar neurochemical processes in fish as in mammals may control impulsivity, as operationally defined by anticipatory responses on a continuous performance task such as this, making zebrafish potentially a good model for exploring the molecular basis of impulse control disorders and for first-round drug screening. PMID:24481568

  10. A simulation and time series analysis of reaction- diffusion equations in biological pattern formation

    NASA Astrophysics Data System (ADS)

    Cooper, Crystal Diane

    A computer program was modified to model the dynamics of morphogen concentrations in a developing eye of a Xenopus laevis frog. The dynamics were modelled because it is believed that the behavior of the morphogen concentrations determine how the developing eye maps to the brain. The eye in the xenophus grows as a series of rings, and thus this is the model used. The basis for the simulation are experiments done by Sullivan et al. Following the experiment, aIl eye ring is 'split' in half, inverted, and then 'pasted' onto a donor half. The purpose of the program is to replicate and analyze the results that were found experimentally: a graft made on a north to south axis (dorsal to ventral) produces a change in vision along the east to west axis (anterior to posterior). Four modified Gierer-Meinhardt reaction- diffusion equations are used to simulate the operation. In the second part of the research, the program was further modified and a time series analysis was done on the results. It was found that the modified Gierer- Meinhardt equations demonstrated chaotic behavior under certain conditions. The dynamics included fixed points, limit cycles, transient chaos, intermittent chaos, and strange attractors. The creation and destruction of fractal torii was found.

  11. A quantitative real-time polymerase chain reaction assay for the seagrass pathogen Labyrinthula zosterae.

    PubMed

    Bergmann, Nina; Fricke, Birgit; Schmidt, Martina C; Tams, Verena; Beining, Katrin; Schwitte, Hildegard; Boettcher, Anne A; Martin, Daniel L; Bockelmann, Anna-Christina; Reusch, Thorsten B H; Rauch, Gisep

    2011-11-01

    The protist Labyrinthula zosterae (Phylum Bigyra, sensu Tsui et al. 2009) has been identified as a causative agent of wasting disease in eelgrass (Zostera marina), of which the most intense outbreak led to the destruction of 90% of eelgrass beds in eastern North America and western Europe in the 1930s. Outbreaks still occur today, albeit at a smaller scale. Traditionally, L. zosterae has been quantified by measuring the necrotic area of Z. marina leaf tissue. This indirect method can however only lead to a very rough estimate of pathogen load. Here, we present a quantitative real-time polymerase chain reaction (qPCR) approach to directly detect and quantify L. zosterae in eelgrass tissue. Based on the internal transcribed spacer (ITS) sequences of rRNA genes, species-specific primers were designed. Using our qPCR, we were able to quantify accurately and specifically L. zosterae load both from culture and eelgrass leaves using material from Europe and North America. Our detection limit was less than one L. zosterae cell. Our results demonstrate the potential of this qPCR assay to provide rapid, accurate and sensitive molecular identification and quantification of L. zosterae. In view of declining seagrass populations worldwide, this method will provide a valuable tool for seagrass ecologists and conservation projects.

  12. Skill-specific changes in somatosensory-evoked potentials and reaction times in baseball players.

    PubMed

    Yamashiro, Koya; Sato, Daisuke; Onishi, Hideaki; Yoshida, Takuya; Horiuchi, Yoko; Nakazawa, Sho; Maruyama, Atsuo

    2013-03-01

    Athletic training is known to induce neuroplastic alterations in specific somatosensory circuits, which are reflected by changes in short-latency somatosensory-evoked potentials (SEPs). The aim of this study is to clarify whether specific training in athletes affects the long-latency SEPs related to information processing of stimulation. The long-latency SEPs P100 and N140 were recorded at midline cortical electrode positions (Fz, Cz, and Pz) in response to stimulation of the index finger of the dominant hand in fifteen baseball players (baseball group) and in fifteen athletes in sports such as swimming, track and field events, and soccer (sports group) that do not require fine somatosensory discrimination or motor control of the hand. The long-latency SEPs were measured under a passive condition (no response required) and a reaction time (RT) condition in which subjects were instructed to rapidly push a button in response to stimulus presentation. The peak P100 and peak N140 latencies and RT were significantly shorter in the baseball group than the sports group. Moreover, there were significant positive correlations between RT and both the peak P100 and the peak N140 latencies. Specific athletic training regimens that involve the hand may induce neuroplastic alterations in the cortical hand representation areas playing a vital role in rapid sensory processing and initiation of motor responses.

  13. Perceptual effect on motor learning in the serial reaction-time task.

    PubMed

    Kemény, Ferenc; Lukács, Agnes

    2011-01-01

    Although the Serial Reaction-Time Task has been an effective tool in studying procedural learning, there is still a debate as to whether learning in the task is effector-based, stimulus-based, or response-based. In this article, the authors contribute to this debate by contrasting response- and stimulus-based learning by manipulating them selectively and simultaneously. Results show that (a) participants learned response sequences in the absence of stimulus-specific perceptual sequence information but (b) not stimulus sequences without corresponding response information. In a third condition, response sequence and stimulus frequency information were in conflict, and each effect decreased learning in the other domain. Overall, our findings show that learning in these tasks is primarily motor-based, but it is also constrained by relatively salient perceptual information. Together with earlier findings in the literature, the findings also suggest a task and stimulus-arrangement-specific interaction between motor and perceptual learning, where relevance and salience of the specific information plays a crucial role.

  14. Real-time polymerase chain reaction for the diagnosis of necrotizing herpes stromal keratitis

    PubMed Central

    Ma, Jun-Xin; Wang, Lin-Nong; Zhou, Ru-Xia; Yu, Yang; Du, Tong-Xin

    2016-01-01

    AIM To design, optimize and validate a rapid, internally controlled real-time polymerase chain reaction (RT-PCR) test for herpes simplex virus (HSV) in the diagnosis of necrotizing herpes stromal keratitis. METHODS Tears alone or together with corneal epithelium scrapings from 30 patients (30 eyes) suspected of necrotizing herpes stromal keratitis were tested for HSV DNA by RT-PCR. The samples were collected during the first visit and then on the subsequent 7, 14, 28, 42, and 56d. The symptoms of the patients were scored before treatment to determine the correlation between HSV concentration in the corneal epithelium scrapings and clinical scores. RESULTS The positive rate (46.4%) in the corneal epithelium group before the therapy was significantly higher than that (13.3%) in the tears group (P=0.006). There were 13 positive HSV patients before the therapy, the concentration of HSV DNA in corneal epithelium scrapings group was significantly higher than that in the tears group (paired t-test, P=0.0397). Multilevel mixed-effects model analysis showed that the difference between the corneal epithelium scrapings group and the tears group was statistically significant (P=0.0049). The Spearman rank correlation analysis indicated a positive correlation between the HSV concentration in the corneal epithelium scrapings and clinical scores before the treatment (r=0.844, P<0.0001). CONCLUSION RT-PCR appears to be a powerful molecular tool for the diagnosis of necrotizing herpes stromal keratitis. PMID:27275421

  15. Energetics of growth of Aspergillus tamarii in a biological real-time reaction calorimeter.

    PubMed

    Dhandapani, Balaji; Mahadevan, Surianarayanan; Mandal, Asit Baran

    2012-03-01

    Fungal cultivation in a biological real-time reaction calorimeter (BioRTCal) is arduous due to the heterogeneous nature of the system and difficulty in optimizing the process variables. The aim of this investigation is to monitor the growth of fungi Aspergillus tamarii MTCC 5152 in a calorimeter. Experiments carried out with a spore concentration of 10(5) spores/mL indicate that the growth based on biomass and heat generation profiles was comparable to those obtained hitherto. Heat yield due to biomass growth, substrate uptake, and oxygen uptake rate was estimated from calorimetric experiments. The results would be useful in fermenter design and scale-up. Heat of combustion of fungal biomass was determined experimentally and compared to the four models reported so far. The substrate concentration had significant effects on pellet formation with variation in pellet porosity and apparent density. Metabolic heat generation is an online process variable portraying the instantaneous activity of monitoring fungal growth and BioRTCal is employed to measure the exothermic heat in a noninvasive way. PMID:22113563

  16. Heavy-Ion Reactions in Time-dependent Hartree-Fock

    SciTech Connect

    Maruhn, J.A.

    2005-03-31

    Nuclear collisions at low energies present a unique opportunity for the study of degenerate Fermi systems far from equilibrium. Their behavior shows a rich variety: from complete fusion through highly nonelastic collisions to grazing situations with a complicated interplay of collective and single-particle degrees of freedom. The time-dependent Hartree-Fock approximation assumes a dominance of Pauli exclusion, ignoring the two-body collisions and instead using the mean field as the dominant dynamic quantity. For a class of zero-range effective interactions (the so-called Skyrme forces) it is possible to numerically solve the equations of motion to obtain a description of reactions that is parameter-free in the sense that the forces are fitted exclusively to nuclear ground-state properties. In this talk I give an overview of the theoretical issues, ignoring much of the technical detail of nuclear theory involved in such studies, and instead concentrating on the interesting consequences of the nonlinear coupling through the mean field: the spurious interaction between the different exit channels, the 'one-body dissipation' mechanism and the essential semiclassical nature of the approach.

  17. A Flow-through Reaction Cell that Couples Time-resolved X-ray Diffraction with Stable Isotope Analysis

    SciTech Connect

    Hanson, J.C.; Wall, A.J.; Heaney, P.J.; Mathur, R.; Post, J.E.; Eng, P.J.

    2011-04-01

    A non-metallic flow-through reaction cell is described, designed for in situ time-resolved X-ray diffraction coupled with stable isotope analysis. The experimental setup allows the correlation of Cu isotope fractionation with changes in crystal structure during copper sulfide dissolution. This flow-through cell can be applied to many classes of fluid-mineral reactions that involve dissolution or ion exchange.

  18. Kinetic Analysis of Parallel-Consecutive First-Order Reactions with a Reversible Step: Concentration-Time Integrals Method

    ERIC Educational Resources Information Center

    Mucientes, A. E.; de la Pena, M. A.

    2009-01-01

    The concentration-time integrals method has been used to solve kinetic equations of parallel-consecutive first-order reactions with a reversible step. This method involves the determination of the area under the curve for the concentration of a given species against time. Computer techniques are used to integrate experimental curves and the method…

  19. Analysis of Reaction Products and Conversion Time in the Pyrolisis of Cellulose and Wood Particles

    NASA Technical Reports Server (NTRS)

    Miller, R. S.; Bellan, J.

    1996-01-01

    A detailed mathematical model is presented for the temporal and spatial accurate modeling of solid-fluid reactions in porous particles for which volumetric reaction rate data is known a priori and both the porosity and the permeability of the particle are large enough to allow for continuous gas flow.

  20. Empowering or Disabling? Emotional Reactions to Assessment amongst Part-Time Adult Students

    ERIC Educational Resources Information Center

    Cramp, Andy; Lamond, Catherine; Coleyshaw, Liz; Beck, Sue

    2012-01-01

    This article focuses on emotional reactions to learning and assessment. It draws on a qualitative research project involving first-generation adult students on a foundation degree programme. Endorsing the notion of emotional reactions as situated in participants' lived power relations, we map out emotional patterns to Semester 1 and then explore…

  1. Procedural Performance Benefits after Excitotoxic Hippocampal Lesions in the Rat Sequential Reaction Time Task.

    PubMed

    Busse, Sebastian; Schwarting, Rainer K W

    2016-01-01

    It is widely agreed upon that hippocampal function is linked to episodic-like and spatial memory across various species, for example, rodents. However, the interplay between hippocampal function and other types of learning and memory, like procedural stimulus-response or sequential learning, is less clear. Recently (Eckart et al. in Hippocampus 22:1202-1214, 2012), we showed that excitotoxic hippocampal lesions, which mainly affected its dorsal part, led not only to the expected deficits in a spatial and episodic-like memory task, namely the object place recognition test, but also to substantial improvements in terms of speed and accuracy in a rat adaption of the human sequential reaction time task (SRTT). The design of that experiment, however, which included fixed test durations per training day, led to the fact that lesioned animals gained more instrumental experience, which may partly have accounted for their enhanced performance. In order to rule out such a potential confound, we performed the present experiment on rats with similar ibotenic lesions aiming at the dorsal hippocampus, but we now kept the amount of correct instrumental responses and reinforcements on the same level as in controls. Our data revealed that lesioned animals were still able to complete the SRTT in a substantially smaller amount of time, when compared to control and sham-operated animals, although no differences were observable in terms of speed or accuracy. Also, the animals with lesions showed impaired extinction in a subsequent test where rewards were omitted. The former effect can primarily be attributed to shorter post-reinforcement pauses in the lesioned animals, and the possible mechanisms of this and the extinction effect will be addressed in the discussion.

  2. Widely applicable MATLAB routines for automated analysis of saccadic reaction times.

    PubMed

    Leppänen, Jukka M; Forssman, Linda; Kaatiala, Jussi; Yrttiaho, Santeri; Wass, Sam

    2015-06-01

    Saccadic reaction time (SRT) is a widely used dependent variable in eye-tracking studies of human cognition and its disorders. SRTs are also frequently measured in studies with special populations, such as infants and young children, who are limited in their ability to follow verbal instructions and remain in a stable position over time. In this article, we describe a library of MATLAB routines (Mathworks, Natick, MA) that are designed to (1) enable completely automated implementation of SRT analysis for multiple data sets and (2) cope with the unique challenges of analyzing SRTs from eye-tracking data collected from poorly cooperating participants. The library includes preprocessing and SRT analysis routines. The preprocessing routines (i.e., moving median filter and interpolation) are designed to remove technical artifacts and missing samples from raw eye-tracking data. The SRTs are detected by a simple algorithm that identifies the last point of gaze in the area of interest, but, critically, the extracted SRTs are further subjected to a number of postanalysis verification checks to exclude values contaminated by artifacts. Example analyses of data from 5- to 11-month-old infants demonstrated that SRTs extracted with the proposed routines were in high agreement with SRTs obtained manually from video records, robust against potential sources of artifact, and exhibited moderate to high test-retest stability. We propose that the present library has wide utility in standardizing and automating SRT-based cognitive testing in various populations. The MATLAB routines are open source and can be downloaded from http://www.uta.fi/med/icl/methods.html .

  3. Characterizing Olfactory Binary Mixture Interactions in Fischer 344 Rats Using Behavioral Reaction Times

    PubMed Central

    Yoder, Wendy M.; Gaynor, Leslie; Windham, Ethan; Lyman, Michelle; Munizza, Olivia; Setlow, Barry; Bizon, Jennifer L.

    2015-01-01

    Response times provide essential subthreshold perceptual data that extend beyond accuracy alone. Behavioral reaction times (RTs) were used to characterize rats’ ability to detect individual odorants in a series of complimentary binary odorant mixture ratios. We employed an automated, liquid-dilution olfactometer to train Fischer 344 rats (N = 8) on an odor identification task using nonreinforced probe trials. Binary mixture ratios composed of aliphatic odorants (citral and octanol) were arranged such that relative contributions of the 2 components varied systematically by a factor of 1% (v/v). Odorant concentrations for the target (S+), control (S−), and mixture (S+:S−) odorants were presented relative to threshold for each rat. Rats were initially trained to respond by licking at a spout to obtain liquid reward for either citral or octanol as the reinforced target (S+) odorant. After achieving 100% accuracy, rats were transferred to variable ratio (VR 2) reinforcement for correct responding. Nonreinforced probe trials (2 per block of 22 trials) were tested for each mixture ratio and recorded as either S+ (rats lick-responded in the presence of the mixture) or S− (rats refrained from licking), thereby indicating detection of the trained, S+ odorant. To determine the perceived salience for each ratio, RTs (latency from odorant onset to lick response) were recorded for each trial. Consistent with previous studies, RTs for both odorants were shortest (~150–200ms) when the probe trials consisted of a single, monomolecular component. Binary mixtures that contained as little as 1% of the S−, nontarget odorant, however, were sufficiently different perceptually to increase behavioral RTs (i.e., rats hesitated longer before responding); RTs changed systematically as a function of the binary ratio. Interestingly, the rate of RT change was dependent on which odorant served as the S+, suggesting an asymmetric interaction between the 2 odorants. The data demonstrate

  4. Comparison of Motor Inhibition in Variants of the Instructed-Delay Choice Reaction Time Task.

    PubMed

    Quoilin, Caroline; Lambert, Julien; Jacob, Benvenuto; Klein, Pierre-Alexandre; Duque, Julie

    2016-01-01

    Using instructed-delay choice reaction time (RT) paradigms, many previous studies have shown that the motor system is transiently inhibited during response preparation: motor-evoked potentials (MEPs) elicited by transcranial magnetic stimulation (TMS) over the primary motor cortex are typically suppressed during the delay period. This effect has been observed in both selected and non-selected effectors, although MEP changes in selected effectors have been more inconsistent across task versions. Here, we compared changes in MEP amplitudes in three different variants of an instructed-delay choice RT task. All variants required participants to choose between left and right index finger movements but the responses were either provided "in the air" (Variant 1), on a regular keyboard (Variant 2), or on a response device designed to control from premature responses (Variant 3). The task variants also differed according to the visual layout (more concrete in Variant 3) and depending on whether participants received a feedback of their performance (absent in Variant 1). Behavior was globally comparable between the three variants of the task although the propensity to respond prematurely was highest in Variant 2 and lowest in Variant 3. MEPs elicited in a non-selected hand were similarly suppressed in the three variants of the task. However, significant differences emerged when considering MEPs elicited in the selected hand: these MEPs were suppressed in Variants 1 and 3 whereas they were often facilitated in Variant 2, especially in the right dominant hand. In conclusion, MEPs elicited in selected muscles seem to be more sensitive to small variations to the task design than those recorded in non-selected effectors, probably because they reflect a complex combination of inhibitory and facilitatory influences on the motor output system. Finally, the use of a standard keyboard seems to be particularly inappropriate because it encourages participants to respond promptly with no

  5. Saccadic reaction times to audiovisual stimuli show effects of oscillatory phase reset.

    PubMed

    Diederich, Adele; Schomburg, Annette; Colonius, Hans

    2012-01-01

    Initiating an eye movement towards a suddenly appearing visual target is faster when an accessory auditory stimulus occurs in close spatiotemporal vicinity. Such facilitation of saccadic reaction time (SRT) is well-documented, but the exact neural mechanisms underlying the crossmodal effect remain to be elucidated. From EEG/MEG studies it has been hypothesized that coupled oscillatory activity in primary sensory cortices regulates multisensory processing. Specifically, it is assumed that the phase of an ongoing neural oscillation is shifted due to the occurrence of a sensory stimulus so that, across trials, phase values become highly consistent (phase reset). If one can identify the phase an oscillation is reset to, it is possible to predict when temporal windows of high and low excitability will occur. However, in behavioral experiments the pre-stimulus phase will be different on successive repetitions of the experimental trial, and average performance over many trials will show no signs of the modulation. Here we circumvent this problem by repeatedly presenting an auditory accessory stimulus followed by a visual target stimulus with a temporal delay varied in steps of 2 ms. Performing a discrete time series analysis on SRT as a function of the delay, we provide statistical evidence for the existence of distinct peak spectral components in the power spectrum. These frequencies, although varying across participants, fall within the beta and gamma range (20 to 40 Hz) of neural oscillatory activity observed in neurophysiological studies of multisensory integration. Some evidence for high-theta/alpha activity was found as well. Our results are consistent with the phase reset hypothesis and demonstrate that it is amenable to testing by purely psychophysical methods. Thus, any theory of multisensory processes that connects specific brain states with patterns of saccadic responses should be able to account for traces of oscillatory activity in observable behavior. PMID

  6. Widely applicable MATLAB routines for automated analysis of saccadic reaction times.

    PubMed

    Leppänen, Jukka M; Forssman, Linda; Kaatiala, Jussi; Yrttiaho, Santeri; Wass, Sam

    2015-06-01

    Saccadic reaction time (SRT) is a widely used dependent variable in eye-tracking studies of human cognition and its disorders. SRTs are also frequently measured in studies with special populations, such as infants and young children, who are limited in their ability to follow verbal instructions and remain in a stable position over time. In this article, we describe a library of MATLAB routines (Mathworks, Natick, MA) that are designed to (1) enable completely automated implementation of SRT analysis for multiple data sets and (2) cope with the unique challenges of analyzing SRTs from eye-tracking data collected from poorly cooperating participants. The library includes preprocessing and SRT analysis routines. The preprocessing routines (i.e., moving median filter and interpolation) are designed to remove technical artifacts and missing samples from raw eye-tracking data. The SRTs are detected by a simple algorithm that identifies the last point of gaze in the area of interest, but, critically, the extracted SRTs are further subjected to a number of postanalysis verification checks to exclude values contaminated by artifacts. Example analyses of data from 5- to 11-month-old infants demonstrated that SRTs extracted with the proposed routines were in high agreement with SRTs obtained manually from video records, robust against potential sources of artifact, and exhibited moderate to high test-retest stability. We propose that the present library has wide utility in standardizing and automating SRT-based cognitive testing in various populations. The MATLAB routines are open source and can be downloaded from http://www.uta.fi/med/icl/methods.html . PMID:24788324

  7. An Investigation Of Leg And Trunk Strength And Reaction Times Of Hard-Style Martial Arts Practitioners

    PubMed Central

    Donovan, Oliver O; Cheung, Jeanette; Catley, Maria; McGregor, Alison H.; Strutton, Paul H.

    2006-01-01

    The purpose of this study was to investigate trunk and knee strength in practitioners of hard-style martial arts. An additional objective was to examine reaction times in these participants by measuring simple reaction times (SRT), choice reaction times (CRT) and movement times (MT). Thirteen high-level martial artists and twelve sedentary participants were tested under isokinetic and isometric conditions on an isokinetic dynamometer. Response and movement times were also measured in response to simple and choice auditory cues. Results indicated that the martial arts group generated a greater body-weight adjusted peak torque with both legs at all speeds during isokinetic extension and flexion, and in isometric extension but not flexion. In isokinetic and isometric trunk flexion and extension, martial artists tended to have higher peak torques than controls, but they were not significantly different (p > 0.05). During the SRT and CRT tasks the martial artists were no quicker in lifting their hand off a button in response to the stimulus [reaction time (RT)] but were significantly faster in moving to press another button [movement time (MT)]. In conclusion, the results reveal that training in a martial art increases the strength of both the flexors and extensors of the leg. Furthermore, they have faster movement times to auditory stimuli. These results are consistent with the physical aspects of the martial arts. Key Points Martial artists undertaking hard-style martial arts have greater strength in their knee flexor and extensor muscles as tested under isokinetic testing. Under isometric testing conditions they have stronger knee extensors only. The trunk musculature is generally higher under both conditions of testing in the martial artists, although not significantly. The total reaction times of the martial artists to an auditory stimulus were significantly faster than the control participants. When analysed further it was revealed that the decrease in reaction

  8. An investigation of leg and trunk strength and reaction times of hard-style martial arts practitioners.

    PubMed

    Donovan, Oliver O; Cheung, Jeanette; Catley, Maria; McGregor, Alison H; Strutton, Paul H

    2006-01-01

    The purpose of this study was to investigate trunk and knee strength in practitioners of hard-style martial arts. An additional objective was to examine reaction times in these participants by measuring simple reaction times (SRT), choice reaction times (CRT) and movement times (MT). Thirteen high-level martial artists and twelve sedentary participants were tested under isokinetic and isometric conditions on an isokinetic dynamometer. Response and movement times were also measured in response to simple and choice auditory cues. Results indicated that the martial arts group generated a greater body-weight adjusted peak torque with both legs at all speeds during isokinetic extension and flexion, and in isometric extension but not flexion. In isokinetic and isometric trunk flexion and extension, martial artists tended to have higher peak torques than controls, but they were not significantly different (p > 0.05). During the SRT and CRT tasks the martial artists were no quicker in lifting their hand off a button in response to the stimulus [reaction time (RT)] but were significantly faster in moving to press another button [movement time (MT)]. In conclusion, the results reveal that training in a martial art increases the strength of both the flexors and extensors of the leg. Furthermore, they have faster movement times to auditory stimuli. These results are consistent with the physical aspects of the martial arts. Key PointsMartial artists undertaking hard-style martial arts have greater strength in their knee flexor and extensor muscles as tested under isokinetic testing. Under isometric testing conditions they have stronger knee extensors only.The trunk musculature is generally higher under both conditions of testing in the martial artists, although not significantly.The total reaction times of the martial artists to an auditory stimulus were significantly faster than the control participants. When analysed further it was revealed that the decrease in reaction time

  9. Real-time observation of polymer network formation by liquid- and solid-state NMR revealing multistage reaction kinetics.

    PubMed

    Kovermann, Michael; Saalwächter, Kay; Chassé, Walter

    2012-06-28

    The reaction rate for the end-cross-linking process of vinyl-terminated poly(dimethylsiloxane) by a cross-linker with four Si-H functionalities in the presence of solvent was studied by (1)H liquid-state NMR in dependence of the reaction temperature. The properties of the resulting polymer networks, i.e., the gel-point and the formation of the elastically effective network, were monitored in situ during the reaction by single-evolution-time (1)H double-quantum (SET-DQ) low-field NMR. It was found that the cross-linking kinetics shows no uniform reaction order for the conversions of the functional groups before the topological gelation threshold of the polymer network. The two NMR methods are combined to investigate the formation of the elastically effective network in dependence of the conversion of the functional groups of the precursor polymers and the cross-linker. The high chemical and time resolution of the experiments enabled an in-depth analysis of the reaction kinetics, allowing us to conclude on a multistage model for PDMS network formation by hydrosilylation-based end-linking in the presence of solvent. We found that the nonuniform network formation kinetics originates from a dependence of the apparent reaction rate on the number of the Si-H groups of the cross-linker that have already reacted during the progress of the reaction. The fastest overall reaction rate is observed in a range until each cross-linker has reacted once on average, and a uniform apparent overall reaction order of unity with respect to cross-linker concentration is only found at a later stage, when multiply reacted cross-linker molecules with similar reactivity dominate. PMID:22650309

  10. Reaction time, impulse speed, overall synaptic delay and number of synapses in tactile reaction neuronal circuits of normal subjects and thinner sniffers.

    PubMed

    Chentanez, T; Keatisuwan, W; Akaraphan, A; Chaunchaiyakul, R; Lechanavanich, C; Hiranrat, S; Chaiwatcharaporn, C; Glinsukon, T

    1988-01-01

    In control subjects, warned auditory reaction time (RT) for a given effector organ was less than the warned visual RT for the same organ. The RT of the circuits between eye or ear or sites of tactile stimulation (SOS) and the index fingers were significantly shorter than that between eye or ear or the same SOS and the right or left big toes. The greater the distance between the SOS and the brain the longer the RT of the response by a given effector organ. The overall signal speed (OASS) from the neck to the index finger was less than that from the neck to the big toe. The OASS from the neck to a given effector was less than that from the toe to the same effector. Sensory nerve impulse speed was slightly faster than motor nerve impulse speed. The overall synaptic delay and estimated number of synapses (ENOS) of simple tactile reaction neuronal circuits of normal subjects did not significantly vary with site of tactile stimulation or effector organ. The mean number of synapses of various tactile reaction neuronal circuits of normal subjects was estimated to be between 69 and 77, which is far greater than the number of synapses in the touch-tactile and motor pathways combined. The overall synaptic delay in the tactile reaction neuronal circuits between SOS and the left and right big toes were significantly lower in sniffers than in control subjects. This may be due to a decrease in either the average synaptic delay, the number of synapses, or both in the tactile reaction neuronal circuits between sites of stimulation and big toes (but not index fingers) in sniffers. PMID:3393601

  11. Effect of inhaled crystalline silica in a rat model: time course of pulmonary reactions.

    PubMed

    Castranova, Vincent; Porter, Dale; Millecchia, Lyndell; Ma, Jane Y C; Hubbs, Ann F; Teass, Alexander

    2002-01-01

    Numerous investigations have been conducted to elucidate mechanisms involved in the initiation and progression of silicosis. However, most of these studies involved bolus exposure of rats to silica, i.e. intratracheal instillation or a short duration inhalation exposure to a high dose of silica. Therefore, the question of pulmonary overload has been an issue in these studies. The objective of the current investigation was to monitor the time course of pulmonary reactions of rats exposed by inhalation to a non-overload level of crystalline silica. To accomplish this, rats were exposed to 15 mg/m3 silica, 6 h/day, 5 days/week for up to 116 days of exposure. At various times (5-116 days exposure), animals were sacrificed and silica lung burden, lung damage, inflammation, NF-KB activation, reactive oxygen species and nitric oxide production, cytokine production, alveolar type II epithelial cell activity, and fibrosis were monitored. Activation of NF-KB/DNA binding in BAL cells was evident after 5 days of silica inhalation and increased linearly with continued exposure. Parameters of pulmonary damage, inflammation and alveolar type II epithelial cell activity rapidly increased to a significantly elevated but stable new level through the first 41 days of exposure and increased at a steep rate thereafter. Pulmonary fibrosis was measurable only after this explosive rise in lung damage and inflammation, as was the steep increase in TNF-alpha and IL-1 production from BAL cells and the dramatic rise in lavageable alveolar macrophages. Indicators of oxidant stress and pulmonary production of nitric oxide exhibited a time course which was similar to that for lung damage and inflammation with the steep rise correlating with initiation of pulmonary fibrosis. Staining for iNOS and nitrotyrosine was localized in granulomatous regions of the lung and bronchial associated lymphoid tissue. Therefore, these data demonstrate that the generation of oxidants and nitric oxide, in

  12. On the time dependence of rate coefficients of irreversible reactions between reactants with anisotropic reactivity in liquid solutions

    NASA Astrophysics Data System (ADS)

    Ivanov, Konstantin L.; Lukzen, Nikita N.; Doktorov, Alexander B.

    2016-08-01

    Time dependence of the rate coefficients of sterically specific reactions is analyzed theoretically. Generally, such reactions exhibit a non-trivial dependence of their rate constant on the steric factor, f < 1, which is defined as the fraction of reactive surface area. Notably, the rate constant of a diffusion-controlled reaction is proportional not to f but, counter-intuitively, to √{ f } due to partial averaging of the reaction anisotropy by translational diffusion. Here we demonstrate that the effective steric factor of a diffusion-influenced reaction is strongly time-dependent, increasing from f to √{ f } . When reactants have several active sites, these sites "interfere" each other in the sense that the rate constant depends on their relative positions. We demonstrate that such an interference effect is strongly time-dependent as well: it is absent at t = 0 but builds up with time. We argue that the outlined effects are also of importance for calculating the fluorescence quenching rate constants.

  13. Type I photosensitized reactions of oxopurines. Kinetics and thermodynamics of the reaction with triplet benzophenone by time-resolved photoacoustic spectroscopy

    NASA Astrophysics Data System (ADS)

    Murgida, Daniel H.; Erra Balsells, Rosa; Crippa, Pier Raimondo; Viappiani, Cristiano

    1998-09-01

    Benzophenone photosensitized reactions of caffeine, theophylline and theobromine were investigated in acetonitrile by time-resolved laser-induced photoacoustics. In the three cases global quenching rate constants of triplet benzophenone were measured as a function of temperature and it was observed that this is a non-activated process. Besides, for theobromine and theophylline heats for NH hydrogen abstraction reactions were determined. In agreement with semiempirical calculation predictions, hydrogen abstraction is thermodynamically more favorable and faster for theophylline (Δ H=-265 kJ mol -1, kr=9.6×10 8 M -1 s -1) than for theobromine (Δ H=-168 kJ mol -1, kr=3.7×10 8 M -1 s -1).

  14. Real-time electrochemical monitoring of the polymerase chain reaction by mediated redox catalysis.

    PubMed

    Deféver, Thibaut; Druet, Michel; Rochelet-Dequaire, Murielle; Joannes, Martine; Grossiord, Céline; Limoges, Benoit; Marchal, Damien

    2009-08-19

    We described the proof-of-principle of a nonoptical real-time PCR that uses cyclic voltammetry for indirectly monitoring the amplified DNA product generated in the PCR reaction solution after each PCR cycle. To enable indirect measurement of the amplicon produced throughout PCR, we monitor electrochemically the progressive consumption (i.e., the decrease of concentration) of free electroactive deoxynucleoside triphosphates (dNTPs) used for DNA synthesis. This is accomplished by exploiting the fast catalytic oxidation of native deoxyguanosine triphosphate (dGTP) or its unnatural analogue 7-deaza-dGTP by the one-electron redox catalysts Ru(bpy)(3)(3+) (with bpy = 2,2'-bipyridine) or Os(bpy)(3)(3+) generated at an electrode. To demonstrate the feasibility of the method, a disposable array of eight miniaturized self-contained electrochemical cells (working volume of 50 microL) has been developed and implemented in a classical programmable thermal cycler and then tested with the PCR amplification of two illustrated examples of real-world biological target DNA sequences (i.e., a relatively long 2300-bp sequence from the bacterial genome of multidrug-resistant Achromobacter xylosoxidans and a shorter 283-bp target from the human cytomegalovirus). Although the method works with both mediator/base couples, the catalytic peak current responses recorded with the Ru(bpy)(3)(3+)/dGTP couple under real-time PCR conditions are significantly affected by a continuous current drift and interference with the background solvent discharge, thus leading to poorly reproducible data. Much more reproducible and reliable results are finally obtained with the Os(bpy)(3)(3+)/7-deaza-dGTP, a result that is attributed to the much lower anodic potential at which the catalytic oxidation of 7-deaza-dGTP by Os(bpy)(3)(3+) is detected. Under these conditions, an exponential decrease of the catalytic signal as a function of the number of PCR cycles is obtained, allowing definition of a cycle

  15. Time-Dependent Wave Packet Study of the H2 + CH3 → H + CH4 Reaction.

    PubMed

    Zhang, Zhaojun; Chen, Jun; Yang, Minghui; Zhang, Dong H

    2015-12-17

    The initial state selected time-dependent wave packet method has been developed to study the H2 + CH3 → H + CH4 reaction, by employing the seven- and eight-dimensional models proposed by Palma and Clary in which the nonreacting CH3 moiety is restricted in C3v symmetry. Total reaction probabilities and integral cross sections were calculated for the ground and a number of vibrationally excited initial states to investigate the effects of vibrational excitations of both reagents on the reaction. The eight-dimensional calculations showed that the CH stretching excitation does not have any important effect on the reaction and the seven-dimensional model with the CH bond length fixed works very well for the reaction. The excitation of H2 vibrations could enhance the reaction but is less effective than the translation in the low energy region. In contrast, the first umbrella excitation is very effective on reducing the reaction threshold. The calculated rate constants are found to be in good agreement with available experimental measurements and other theoretical results.

  16. Time-Dependent Wave Packet Study of the H2 + CH3 → H + CH4 Reaction.

    PubMed

    Zhang, Zhaojun; Chen, Jun; Yang, Minghui; Zhang, Dong H

    2015-12-17

    The initial state selected time-dependent wave packet method has been developed to study the H2 + CH3 → H + CH4 reaction, by employing the seven- and eight-dimensional models proposed by Palma and Clary in which the nonreacting CH3 moiety is restricted in C3v symmetry. Total reaction probabilities and integral cross sections were calculated for the ground and a number of vibrationally excited initial states to investigate the effects of vibrational excitations of both reagents on the reaction. The eight-dimensional calculations showed that the CH stretching excitation does not have any important effect on the reaction and the seven-dimensional model with the CH bond length fixed works very well for the reaction. The excitation of H2 vibrations could enhance the reaction but is less effective than the translation in the low energy region. In contrast, the first umbrella excitation is very effective on reducing the reaction threshold. The calculated rate constants are found to be in good agreement with available experimental measurements and other theoretical results. PMID:26495964

  17. Interference between postural control and spatial vs. non-spatial auditory reaction time tasks in older adults.

    PubMed

    Fuhrman, Susan I; Redfern, Mark S; Jennings, J Richard; Furman, Joseph M

    2015-01-01

    This study investigated whether spatial aspects of an information processing task influence dual-task interference. Two groups (Older/Young) of healthy adults participated in dual-task experiments. Two auditory information processing tasks included a frequency discrimination choice reaction time task (non-spatial task) and a lateralization choice reaction time task (spatial task). Postural tasks included combinations of standing with eyes open or eyes closed on either a fixed floor or a sway-referenced floor. Reaction times and postural sway via center of pressure were recorded. Baseline measures of reaction time and sway were subtracted from the corresponding dual-task results to calculate reaction time task costs and postural task costs. Reaction time task cost increased with eye closure (p = 0.01), sway-referenced flooring (p < 0.0001), and the spatial task (p = 0.04). Additionally, a significant (p = 0.05) task x vision x age interaction indicated that older subjects had a significant vision X task interaction whereas young subjects did not. However, when analyzed by age group, the young group showed minimal differences in interference for the spatial and non-spatial tasks with eyes open, but showed increased interference on the spatial relative to non-spatial task with eyes closed. On the contrary, older subjects demonstrated increased interference on the spatial relative to the non-spatial task with eyes open, but not with eyes closed. These findings suggest that visual-spatial interference may occur in older subjects when vision is used to maintain posture.

  18. [Development of a real-time polymerase chain reaction method for the identification of Candida species].

    PubMed

    Ağca, Harun; Dalyan Cilo, Burcu; Özmerdiven, Gülşah Ece; Sağlam, Sezcan; Ener, Beyza

    2015-01-01

    Candida species are one of the major causes of nosocomial infections and are the fourth most common agent involved in bloodstream infections. The impact of non-albicans Candida species is increasing, however C.albicans is still the most common species. Since the antifungal susceptibility pattern among Candida spp. may be different, rapid diagnosis and identification of non-albicans Candida spp. are important for the determination of antifungal agents that will be used for treatment. The aim of the study was to describe a real-time polymerase chain reaction (Rt-PCR) assay that rapidly detects, identifies and quantitates Candida species from blood culture samples. A total of 50 consecutive positive blood culture bottles (BACTEC, Beckton Dickinson, USA) identified at our laboratory between June-November 2013, were included in the study. Reference strains of Candida spp. (C.albicans ATCC 10231, C.glabrata ATCC 90030, C.tropicalis ATCC 1021, C.krusei ATCC 6258, C.parapsilosis ATCC 22019 and C. dubliniensis CD36) grown on Sabouraud dextrose agar were used for quality control. BACTEC bottles that were positive for Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus were also studied to search the cross-reactivity. A commercial kit (Zymo Research, USA) was used for DNA extraction. Real-time PCR was performed on LightCycler 480 (Roche, Germany) with primers and probes specific for 18S rRNA of Candida species. Twenty microlitres of the reaction mix contained 2 μl of extracted DNA, 2 μl of LightCycler Fast Start DNA Master Probe (Roche Diagnostics, Germany), 2 μl of MgCl(2) (5 mmol), 2 μl of 10x PCR buffer (Roche Diagnostics, Germany), 0.5 μl of each primer (0.01 nmol/μl) and 1 μl of each probe (0.1 μmol/μl) (TibMolBiol, Germany). Amplification was performed using the following conditions; 95°C for 10 mins and 50 cycles of denaturation at 95°C for 10 secs, annealing at 62°C for 10 secs and polymerisation at 72°C for 20 secs. A melting curve was

  19. [Development of a real-time polymerase chain reaction method for the identification of Candida species].

    PubMed

    Ağca, Harun; Dalyan Cilo, Burcu; Özmerdiven, Gülşah Ece; Sağlam, Sezcan; Ener, Beyza

    2015-01-01

    Candida species are one of the major causes of nosocomial infections and are the fourth most common agent involved in bloodstream infections. The impact of non-albicans Candida species is increasing, however C.albicans is still the most common species. Since the antifungal susceptibility pattern among Candida spp. may be different, rapid diagnosis and identification of non-albicans Candida spp. are important for the determination of antifungal agents that will be used for treatment. The aim of the study was to describe a real-time polymerase chain reaction (Rt-PCR) assay that rapidly detects, identifies and quantitates Candida species from blood culture samples. A total of 50 consecutive positive blood culture bottles (BACTEC, Beckton Dickinson, USA) identified at our laboratory between June-November 2013, were included in the study. Reference strains of Candida spp. (C.albicans ATCC 10231, C.glabrata ATCC 90030, C.tropicalis ATCC 1021, C.krusei ATCC 6258, C.parapsilosis ATCC 22019 and C. dubliniensis CD36) grown on Sabouraud dextrose agar were used for quality control. BACTEC bottles that were positive for Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus were also studied to search the cross-reactivity. A commercial kit (Zymo Research, USA) was used for DNA extraction. Real-time PCR was performed on LightCycler 480 (Roche, Germany) with primers and probes specific for 18S rRNA of Candida species. Twenty microlitres of the reaction mix contained 2 μl of extracted DNA, 2 μl of LightCycler Fast Start DNA Master Probe (Roche Diagnostics, Germany), 2 μl of MgCl(2) (5 mmol), 2 μl of 10x PCR buffer (Roche Diagnostics, Germany), 0.5 μl of each primer (0.01 nmol/μl) and 1 μl of each probe (0.1 μmol/μl) (TibMolBiol, Germany). Amplification was performed using the following conditions; 95°C for 10 mins and 50 cycles of denaturation at 95°C for 10 secs, annealing at 62°C for 10 secs and polymerisation at 72°C for 20 secs. A melting curve was

  20. In-situ nanoelectrospray for high-throughput screening of enzymes and real-time monitoring of reactions.

    PubMed

    Yang, Yuhan; Han, Feifei; Ouyang, Jin; Zhao, Yunling; Han, Juan; Na, Na

    2016-01-01

    The in-situ and high-throughput evaluation of enzymes and real-time monitoring of enzyme catalyzed reactions in liquid phase is quite significant in the catalysis industry. In-situ nanoelectrospray, the direct sampling and ionization method for mass spectrometry, has been applied for high-throughput evaluation of enzymes, as well as the on-line monitoring of reactions. Simply inserting a capillary into a liquid system with high-voltage applied, analytes in liquid reaction system can be directly ionized at the capillary tip with small volume consumption. With no sample pre-treatment or injection procedure, different analytes such as saccharides, amino acids, alkaloids, peptides and proteins can be rapidly and directly extracted from liquid phase and ionized at the capillary tip. Taking irreversible transesterification reaction of vinyl acetate and ethanol as an example, this technique has been used for the high-throughput evaluation of enzymes, fast optimizations, as well as real-time monitoring of reaction catalyzed by different enzymes. In addition, it is even softer than traditional electrospray ionization. The present method can also be used for the monitoring of other homogenous and heterogeneous reactions in liquid phases, which will show potentials in the catalysis industry.

  1. A Flight-Calibrated Methodology for Determination of Cassini Thruster On-Times for Reaction Wheel Biases

    NASA Technical Reports Server (NTRS)

    Sarani, Sam

    2010-01-01

    The Cassini spacecraft, the largest and most complex interplanetary spacecraft ever built, continues to undertake unique scientific observations of planet Saturn, Titan, Enceladus, and other moons of the ring world. In order to maintain a stable attitude during the course of its mission, this three-axis stabilized spacecraft uses two different control systems: the Reaction Control System (or RCS) and the Reaction Wheel Assembly (RWA) control system. In the course of its mission, Cassini performs numerous reaction wheel momentum biases (or unloads) using its reaction control thrusters. The use of the RCS thrusters often imparts undesired velocity changes (delta Vs) on the spacecraft and it is crucial for Cassini navigation and attitude control teams to be able to, quickly but accurately, predict the hydrazine usage and delta V vector in Earth Mean Equatorial (J2000) inertial coordinates for reaction wheel bias events, without actually having to spend time and resources simulating the event in a dynamic or hardware-in-the-loop simulation environments. The flight-calibrated methodology described in this paper, and the ground software developed thereof, are designed to provide the RCS thruster on-times, with acceptable accuracy and without any form of dynamic simulation, for reaction wheel biases, along with the hydrazine usage and the delta V in EME-2000 inertial frame.

  2. Effects of Stimulant Medication, Incentives, and Event Rate on Reaction Time Variability in Children With ADHD

    PubMed Central

    Epstein, Jeffery N; Brinkman, William B; Froehlich, Tanya; Langberg, Joshua M; Narad, Megan E; Antonini, Tanya N; Shiels, Keri; Simon, John O; Altaye, Mekibib

    2011-01-01

    This study examined the effects of methylphenidate (MPH) on reaction time (RT) variability in children with attention deficit hyperactivity disorder (ADHD). Using a broad battery of computerized tasks, and both conventional and ex-Gaussian indicators of RT variability, in addition to within-task manipulations of incentive and event rate (ER), this study comprehensively examined the breadth, specificity, and possible moderators of effects of MPH on RT variability. A total of 93 children with ADHD completed a 4-week within-subject, randomized, double-blind, placebo-controlled crossover trial of MPH to identify an optimal dosage. Children were then randomly assigned to receive either their optimal MPH dose or placebo after which they completed five neuropsychological tasks, each allowing trial-by-trial assessment of RTs. Stimulant effects on RT variability were observed on both measures of the total RT distribution (ie, coefficient of variation) as well as on an ex-Gaussian measure examining the exponential portion of the RT distribution (ie, τ). There was minimal, if any, effect of MPH on performance accuracy or RT speed. Within-task incentive and ER manipulations did not appreciably affect stimulant effects across the tasks. The pattern of significant and pervasive effects of MPH on RT variability, and few effects of MPH on accuracy and RT speed suggest that MPH primarily affects RT variability. Given the magnitude and breadth of effects of MPH on RT variability as well as the apparent specificity of these effects of MPH on RT variability indicators, future research should focus on neurophysiological correlates of effects of MPH on RT variability in an effort to better define MPH pharmacodynamics. PMID:21248722

  3. Tail effect in gravitational radiation reaction: Time nonlocality and renormalization group evolution

    NASA Astrophysics Data System (ADS)

    Galley, Chad R.; Leibovich, Adam K.; Porto, Rafael A.; Ross, Andreas

    2016-06-01

    We use the effective field theory (EFT) framework to calculate the tail effect in gravitational radiation reaction, which enters at the fourth post-Newtonian order in the dynamics of a binary system. The computation entails a subtle interplay between the near (or potential) and far (or radiation) zones. In particular, we find that the tail contribution to the effective action is nonlocal in time and features both a dissipative and a "conservative" term. The latter includes a logarithmic ultraviolet (UV) divergence, which we show cancels against an infrared (IR) singularity found in the (conservative) near zone. The origin of this behavior in the long-distance EFT is due to the point-particle limit—shrinking the binary to a point—which transforms a would-be infrared singularity into an ultraviolet divergence. This is a common occurrence in an EFT approach, which furthermore allows us to use renormalization group (RG) techniques to resum the resulting logarithmic contributions. We then derive the RG evolution for the binding potential and total mass/energy, and find agreement with the results obtained imposing the conservation of the (pseudo) stress-energy tensor in the radiation theory. While the calculation of the leading tail contribution to the effective action involves only one diagram, five are needed for the one-point function. This suggests logarithmic corrections may be easier to incorporate in this fashion. We conclude with a few remarks on the nature of these IR/UV singularities, the (lack of) ambiguities recently discussed in the literature, and the completeness of the analytic post-Newtonian framework.

  4. Labile sleep promotes awareness of abstract knowledge in a serial reaction time task

    PubMed Central

    Kirov, Roumen; Kolev, Vasil; Verleger, Rolf; Yordanova, Juliana

    2015-01-01

    Sleep has been identified as a critical brain state enhancing the probability of gaining insight into covert task regularities. Both non-rapid eye movement (NREM) and rapid eye movement (REM) sleep have been implicated with offline re-activation and reorganization of memories supporting explicit knowledge generation. According to two-stage models of sleep function, offline processing of information during sleep is sequential requiring multiple cycles of NREM and REM sleep stages. However, the role of overnight dynamic sleep macrostructure for insightfulness has not been studied so far. In the present study, we test the hypothesis that the frequency of interactions between NREM and REM sleep stages might be critical for awareness after sleep. For that aim, the rate of sleep stage transitions was evaluated in 53 participants who learned implicitly a serial reaction time task (SRTT) in which a determined sequence was inserted. The amount of explicit knowledge about the sequence was established by verbal recall after a night of sleep following SRTT learning. Polysomnography was recorded in this night and in a control night before and was analyzed to compare the rate of sleep-stage transitions between participants who did or did not gain awareness of task regularity after sleep. Indeed, individual ability of explicit knowledge generation was strongly associated with increased rate of transitions between NREM and REM sleep stages and between light sleep stages and slow wave sleep. However, the rate of NREM–REM transitions specifically predicted the amount of explicit knowledge after sleep in a trait-dependent way. These results demonstrate that enhanced lability of sleep goes along with individual ability of knowledge awareness. Observations suggest that facilitated dynamic interactions between sleep stages, particularly between NREM and REM sleep stages play a role for offline processing which promotes rule extraction and awareness. PMID:26441730

  5. Domain-Specific and Unspecific Reaction Times in Experienced Team Handball Goalkeepers and Novices

    PubMed Central

    Helm, Fabian; Reiser, Mathias; Munzert, Jörn

    2016-01-01

    In our everyday environments, we are constantly having to adapt our behavior to changing conditions. Hence, processing information is a fundamental cognitive activity, especially the linking together of perceptual and action processes. In this context, expertise research in the sport domain has concentrated on arguing that superior processing performance is driven by an advantage to be found in anticipatory processes (see Williams et al., 2011, for a review). This has resulted in less attention being paid to the benefits coming from basic internal perceptual-motor processing. In general, research on reaction time (RT) indicates that practicing a RT task leads to an increase in processing speed (Mowbray and Rhoades, 1959; Rabbitt and Banerji, 1989). Against this background, the present study examined whether the speed of internal processing is dependent on or independent from domain-specific motor expertise in unpredictable stimulus–response tasks and in a double stimulus–response paradigm. Thirty male participants (15 team handball goalkeepers and 15 novices) performed domain-unspecific simple or choice stimulus–response (CSR) tasks as well as CSR tasks that were domain-specific only for goalkeepers. As expected, results showed significantly faster RTs for goalkeepers on domain-specific tasks, whereas novices’ RTs were more frequently excessively long. However, differences between groups in the double stimulus-response paradigm were not significant. It is concluded that the reported expertise advantage might be due to recalling stored perceptual-motor representations for the domain-specific tasks, implying that experience with (practice of) a motor task explicitly enhances the internal processing of other related domain-specific tasks. PMID:27445879

  6. Decreased reaction time variability is associated with greater cardiovascular responses to acute stress.

    PubMed

    Wawrzyniak, Andrew J; Hamer, Mark; Steptoe, Andrew; Endrighi, Romano

    2016-05-01

    Cardiovascular (CV) responses to mental stress are prospectively associated with poor CV outcomes. The association between CV responses to mental stress and reaction times (RTs) in aging individuals may be important but warrants further investigation. The present study assessed RTs to examine associations with CV responses to mental stress in healthy, older individuals using robust regression techniques. Participants were 262 men and women (mean age = 63.3 ± 5.5 years) from the Whitehall II cohort who completed a RT task (Stroop) and underwent acute mental stress (mirror tracing) to elicit CV responses. Blood pressure, heart rate, and heart rate variability were measured at baseline, during acute stress, and through a 75-min recovery. RT measures were generated from an ex-Gaussian distribution that yielded three predictors: mu-RT, sigma-RT, and tau-RT, the mean, standard deviation, and mean of the exponential component of the normal distribution, respectively. Decreased intraindividual RT variability was marginally associated with greater systolic (B = -.009, SE = .005, p = .09) and diastolic (B = -.004, SE = .002, p = .08) blood pressure reactivity. Decreased intraindividual RT variability was associated with impaired systolic blood pressure recovery (B = -.007, SE = .003, p = .03) and impaired vagal tone (B = -.0047, SE = .0024, p = .045). Study findings offer tentative support for an association between RTs and CV responses. Despite small effect sizes and associations not consistent across predictors, these data may point to a link between intrinsic neuronal plasticity and CV responses. PMID:26894967

  7. Single and choice reaction time during prolonged exercise in trained subjects: influence of carbohydrate availability.

    PubMed

    Collardeau, M; Brisswalter, J; Vercruyssen, F; Audiffren, M; Goubault, C

    2001-12-01

    The aim of the present study was to examine the effects of prolonged exercise at the ventilatory threshold and carbohydrate ingestion on single (SRT) and choice (CRT) reaction time. Eight well-trained triathletes completed three testing sessions within a 3-week period. Maximal oxygen uptake was determined in the first test, whereas the second and the third sessions were composed of a 100-min run (treadmill 15 min, overground 70 min, treadmill 15 min) performed at the velocity associated with the ventilatory threshold. During these submaximal tests, the subjects ingested (in random order) 8 ml x kg(-1) body weight of either a placebo (Pl) or 5.5% carbohydrate (CHO) solution prior to the first submaximal run and 2 ml x kg(-1) body weight every 15 min after that. The cognitive tasks were performed before and after exercise for CRT, and before, during each submaximal run and after exercise for SRT. Furthermore, at the end of each submaximal test subjects were asked to report their rating of perceived exertion (RPE). Results showed a significant positive effect of CHO ingestion on RPE and CRT performance at the end of exercise, while no effect of exercise duration was found in the Pl condition. After a 100-min run, during the CHO condition, CRT mean (SD) group values decreased from 688.5 (51) ms to 654 (63) ms, while during the Pl condition, RPE mean group values increased from 11 (2) to 16 (1.02) and CRT mean values remained stable [688 (104) ms vs 676 (73.4) ms, P > 0.05]. No similar effect was observed for SRT. These results suggest that CHO-electrolyte ingestion during a 100-min run results in an improvement in the complex cognitive performance measured at the end of that run. PMID:11822474

  8. Domain-Specific and Unspecific Reaction Times in Experienced Team Handball Goalkeepers and Novices.

    PubMed

    Helm, Fabian; Reiser, Mathias; Munzert, Jörn

    2016-01-01

    In our everyday environments, we are constantly having to adapt our behavior to changing conditions. Hence, processing information is a fundamental cognitive activity, especially the linking together of perceptual and action processes. In this context, expertise research in the sport domain has concentrated on arguing that superior processing performance is driven by an advantage to be found in anticipatory processes (see Williams et al., 2011, for a review). This has resulted in less attention being paid to the benefits coming from basic internal perceptual-motor processing. In general, research on reaction time (RT) indicates that practicing a RT task leads to an increase in processing speed (Mowbray and Rhoades, 1959; Rabbitt and Banerji, 1989). Against this background, the present study examined whether the speed of internal processing is dependent on or independent from domain-specific motor expertise in unpredictable stimulus-response tasks and in a double stimulus-response paradigm. Thirty male participants (15 team handball goalkeepers and 15 novices) performed domain-unspecific simple or choice stimulus-response (CSR) tasks as well as CSR tasks that were domain-specific only for goalkeepers. As expected, results showed significantly faster RTs for goalkeepers on domain-specific tasks, whereas novices' RTs were more frequently excessively long. However, differences between groups in the double stimulus-response paradigm were not significant. It is concluded that the reported expertise advantage might be due to recalling stored perceptual-motor representations for the domain-specific tasks, implying that experience with (practice of) a motor task explicitly enhances the internal processing of other related domain-specific tasks. PMID:27445879

  9. Decreased reaction time variability is associated with greater cardiovascular responses to acute stress

    PubMed Central

    Hamer, Mark; Steptoe, Andrew; Endrighi, Romano

    2016-01-01

    Abstract Cardiovascular (CV) responses to mental stress are prospectively associated with poor CV outcomes. The association between CV responses to mental stress and reaction times (RTs) in aging individuals may be important but warrants further investigation. The present study assessed RTs to examine associations with CV responses to mental stress in healthy, older individuals using robust regression techniques. Participants were 262 men and women (mean age = 63.3 ± 5.5 years) from the Whitehall II cohort who completed a RT task (Stroop) and underwent acute mental stress (mirror tracing) to elicit CV responses. Blood pressure, heart rate, and heart rate variability were measured at baseline, during acute stress, and through a 75‐min recovery. RT measures were generated from an ex‐Gaussian distribution that yielded three predictors: mu‐RT, sigma‐RT, and tau‐RT, the mean, standard deviation, and mean of the exponential component of the normal distribution, respectively. Decreased intraindividual RT variability was marginally associated with greater systolic (B = −.009, SE = .005, p = .09) and diastolic (B = −.004, SE = .002, p = .08) blood pressure reactivity. Decreased intraindividual RT variability was associated with impaired systolic blood pressure recovery (B = −.007, SE = .003, p = .03) and impaired vagal tone (B = −.0047, SE = .0024, p = .045). Study findings offer tentative support for an association between RTs and CV responses. Despite small effect sizes and associations not consistent across predictors, these data may point to a link between intrinsic neuronal plasticity and CV responses. PMID:26894967

  10. Decreased reaction time variability is associated with greater cardiovascular responses to acute stress.

    PubMed

    Wawrzyniak, Andrew J; Hamer, Mark; Steptoe, Andrew; Endrighi, Romano

    2016-05-01

    Cardiovascular (CV) responses to mental stress are prospectively associated with poor CV outcomes. The association between CV responses to mental stress and reaction times (RTs) in aging individuals may be important but warrants further investigation. The present study assessed RTs to examine associations with CV responses to mental stress in healthy, older individuals using robust regression techniques. Participants were 262 men and women (mean age = 63.3 ± 5.5 years) from the Whitehall II cohort who completed a RT task (Stroop) and underwent acute mental stress (mirror tracing) to elicit CV responses. Blood pressure, heart rate, and heart rate variability were measured at baseline, during acute stress, and through a 75-min recovery. RT measures were generated from an ex-Gaussian distribution that yielded three predictors: mu-RT, sigma-RT, and tau-RT, the mean, standard deviation, and mean of the exponential component of the normal distribution, respectively. Decreased intraindividual RT variability was marginally associated with greater systolic (B = -.009, SE = .005, p = .09) and diastolic (B = -.004, SE = .002, p = .08) blood pressure reactivity. Decreased intraindividual RT variability was associated with impaired systolic blood pressure recovery (B = -.007, SE = .003, p = .03) and impaired vagal tone (B = -.0047, SE = .0024, p = .045). Study findings offer tentative support for an association between RTs and CV responses. Despite small effect sizes and associations not consistent across predictors, these data may point to a link between intrinsic neuronal plasticity and CV responses.

  11. CDF-XL: computing cumulative distribution functions of reaction time data in Excel.

    PubMed

    Houghton, George; Grange, James A

    2011-12-01

    In experimental psychology, central tendencies of reaction time (RT) distributions are used to compare different experimental conditions. This emphasis on the central tendency ignores additional information that may be derived from the RT distribution itself. One method for analysing RT distributions is to construct cumulative distribution frequency plots (CDFs; Ratcliff, Psychological Bulletin 86:446-461, 1979). However, this method is difficult to implement in widely available software, severely restricting its use. In this report, we present an Excel-based program, CDF-XL, for constructing and analysing CDFs, with the aim of making such techniques more readily accessible to researchers, including students (CDF-XL can be downloaded free of charge from the Psychonomic Society's online archive). CDF-XL functions as an Excel workbook and starts from the raw experimental data, organised into three columns (Subject, Condition, and RT) on an Input Data worksheet (a point-and-click utility is provided for achieving this format from a broader data set). No further preprocessing or sorting of the data is required. With one click of a button, CDF-XL will generate two forms of cumulative analysis: (1) "standard" CDFs, based on percentiles of participant RT distributions (by condition), and (2) a related analysis employing the participant means of rank-ordered RT bins. Both analyses involve partitioning the data in similar ways, but the first uses a "median"-type measure at the participant level, while the latter uses the mean. The results are presented in three formats: (i) by participants, suitable for entry into further statistical analysis; (ii) grand means by condition; and (iii) completed CDF plots in Excel charts.

  12. Collision Reactions between CN and C2H2: Short-Time Fourier Transform Analysis of AIMD Simulation

    NASA Astrophysics Data System (ADS)

    Tamaoki, Mari; Sakura, Daisuke; Yamauchi, Yusuke; Nakai, Hiromi

    2006-09-01

    Collision reactions between the cyano radical (CN) and unsaturated hydrocarbons (C2H2), which occur in the atmosphere of Saturn's moon Titan, were investigated using ab initio molecular dynamics (AIMD) simulations. The simulation results were categorized into three kinds: nonreactive collision, incorporation, and substitution. Short-time Fourier transform analysis of velocity auto-correlation functions obtained by the AIMD simulations was performed to examine the non-equilibrium condition of the vibrational states. Spectrograms, which correspond to the time evolution of power spectra, clarify the relationship between the three reaction channels and the dynamical changes of the vibrational states.

  13. Comparison of Motor Inhibition in Variants of the Instructed-Delay Choice Reaction Time Task

    PubMed Central

    Quoilin, Caroline; Lambert, Julien; Jacob, Benvenuto; Klein, Pierre-Alexandre; Duque, Julie

    2016-01-01

    Using instructed-delay choice reaction time (RT) paradigms, many previous studies have shown that the motor system is transiently inhibited during response preparation: motor-evoked potentials (MEPs) elicited by transcranial magnetic stimulation (TMS) over the primary motor cortex are typically suppressed during the delay period. This effect has been observed in both selected and non-selected effectors, although MEP changes in selected effectors have been more inconsistent across task versions. Here, we compared changes in MEP amplitudes in three different variants of an instructed-delay choice RT task. All variants required participants to choose between left and right index finger movements but the responses were either provided “in the air” (Variant 1), on a regular keyboard (Variant 2), or on a response device designed to control from premature responses (Variant 3). The task variants also differed according to the visual layout (more concrete in Variant 3) and depending on whether participants received a feedback of their performance (absent in Variant 1). Behavior was globally comparable between the three variants of the task although the propensity to respond prematurely was highest in Variant 2 and lowest in Variant 3. MEPs elicited in a non-selected hand were similarly suppressed in the three variants of the task. However, significant differences emerged when considering MEPs elicited in the selected hand: these MEPs were suppressed in Variants 1 and 3 whereas they were often facilitated in Variant 2, especially in the right dominant hand. In conclusion, MEPs elicited in selected muscles seem to be more sensitive to small variations to the task design than those recorded in non-selected effectors, probably because they reflect a complex combination of inhibitory and facilitatory influences on the motor output system. Finally, the use of a standard keyboard seems to be particularly inappropriate because it encourages participants to respond promptly

  14. Real-time monitoring of mass-transport-related enzymatic reaction kinetics in a nanochannel-array reactor.

    PubMed

    Li, Su-Juan; Wang, Chen; Wu, Zeng-Qiang; Xu, Jing-Juan; Xia, Xing-Hua; Chen, Hong-Yuan

    2010-09-01

    To understand the fundamentals of enzymatic reactions confined in micro-/nanosystems, the construction of a small enzyme reactor coupled with an integrated real-time detection system for monitoring the kinetic information is a significant challenge. Nano-enzyme array reactors were fabricated by covalently linking enzymes to the inner channels of a porous anodic alumina (PAA) membrane. The mechanical stability of this nanodevice enables us to integrate an electrochemical detector for the real-time monitoring of the formation of the enzyme reaction product by sputtering a thin Pt film on one side of the PAA membrane. Because the enzymatic reaction is confined in a limited nanospace, the mass transport of the substrate would influence the reaction kinetics considerably. Therefore, the oxidation of glucose by dissolved oxygen catalyzed by immobilized glucose oxidase was used as a model to investigate the mass-transport-related enzymatic reaction kinetics in confined nanospaces. The activity and stability of the enzyme immobilized in the nanochannels was enhanced. In this nano-enzyme reactor, the enzymatic reaction was controlled by mass transport if the flux was low. With an increase in the flux (e.g., >50 microL min(-1)), the enzymatic reaction kinetics became the rate-determining step. This change resulted in the decrease in the conversion efficiency of the nano-enzyme reactor and the apparent Michaelis-Menten constant with an increase in substrate flux. This nanodevice integrated with an electrochemical detector could help to understand the fundamentals of enzymatic reactions confined in nanospaces and provide a platform for the design of highly efficient enzyme reactors. In addition, we believe that such nanodevices will find widespread applications in biosensing, drug screening, and biochemical synthesis.

  15. Impact of reagent infiltration time on reaction patterns and pasting properties of modified maize and wheat starches.

    PubMed

    Hong, Jung Sun; BeMiller, James N; Huber, Kerry C

    2016-10-20

    The impact of granular and molecular reaction patterns on modified starch properties was investigated as a function of the length of time allowed for reagent to infiltrate starch granules. A fluorescent reagent [5-(4,6-dichlorotriazinyl)aminofluorescein] was dispersed in aqueous normal maize or wheat starch slurries (35%, w/v) for 0, 5, 10, 30, or 60min, after which reaction was initiated by increasing the pH to 11.5 and allowing reaction to proceed for 3h. With increasing lengths of infiltration, the reaction became increasingly homogeneous within the granule interior (matrix) and the AM:AP reactivity ratio increased (wheat starch), as assessed by confocal laser scanning microscopy (CLSM) and size-exclusion chromatography (refractive index and fluorescence detection), respectively. A longer reagent infiltration time also led to a more inhibited (i.e., cross-linked) pasting viscosity, suggesting that both granular and/or molecular reaction patterns were altered by varied reagent infiltration times to ultimately impact modified starch properties.

  16. Time-dependent Hartree-Fock calculations for multinucleon transfer and quasifission processes in the 238U+64Ni reaction

    NASA Astrophysics Data System (ADS)

    Sekizawa, Kazuyuki; Yabana, Kazuhiro

    2016-05-01

    Background: Multinucleon transfer (MNT) and quasifission (QF) processes are dominant processes in low-energy collisions of two heavy nuclei. They are expected to be useful to produce neutron-rich unstable nuclei. Nuclear dynamics leading to these processes depends sensitively on nuclear properties such as deformation and shell structure. Purpose: We elucidate reaction mechanisms of MNT and QF processes involving heavy deformed nuclei, making detailed comparisons between microscopic time-dependent Hartree-Fock (TDHF) calculations and measurements for the 238U+64Ni reaction. Methods: Three-dimensional Skyrme-TDHF calculations are performed. Particle-number projection method is used to evaluate MNT cross sections from the TDHF wave function after collision. Results: Fragment masses, total kinetic energy (TKE), scattering angle, contact time, and MNT cross sections are investigated for the 238U+64Ni reaction. They show reasonable agreements with measurements. At small impact parameters, collision dynamics depends sensitively on the orientation of deformed 238U. In tip (side) collisions, we find a larger (smaller) TKE and a shorter (longer) contact time. In tip collisions, we find a strong influence of quantum shells around 208Pb. Conclusions: It is confirmed that the TDHF calculations reasonably describe both MNT and QF processes in the 238U64Ni reaction. Analyses of this system indicate the significance of the nuclear structure effects such as deformation and quantum shells in nuclear reaction dynamics at low energies.

  17. Robust strand exchange reactions for the sequence-specific, real-time detection of nucleic acid amplicons.

    PubMed

    Jiang, Yu Sherry; Bhadra, Sanchita; Li, Bingling; Wu, Yuefeng Rose; Milligan, John N; Ellington, Andrew D

    2015-03-17

    Loop-mediated isothermal amplification (LAMP) of DNA is a powerful isothermal nucleic acid amplification method that can generate upward of 10(9) copies from less than 100 copies of template DNA within an hour. Unfortunately, although the amplification reactions are extremely powerful, real-time and specific detection of LAMP products remains analytically challenging. In order to both improve the specificity of LAMP detection and to make readout simpler and more reliable, we have replaced the intercalating dye typically used for monitoring in real-time fluorescence with a toehold-mediated strand exchange reaction termed one-step strand displacement (OSD). Due to the inherent sequence specificity of toehold-mediated strand exchange, the OSD reporter could successfully distinguish side products from true amplicons arising from templates corresponding to the biomedically relevant M. tuberculosis RNA polymerase (rpoB) and the melanoma-related biomarker BRAF. OSD allowed the Yes/No detection of rpoB in a complex mixture such as synthetic sputum and also demonstrated single nucleotide specificity in Yes/No detection of a mutant BRAF allele (V600E) in the presence of 20-fold more of the wild-type gene. Real-time detection of different genes in multiplex LAMP reactions also proved possible. The development of simple, readily designed, modular equivalents of TaqMan probes for isothermal amplification reactions should generally improve the applicability of these reactions and may eventually assist with the development of point-of-care tests.

  18. EEG alpha spindles and prolonged brake reaction times during auditory distraction in an on-road driving study.

    PubMed

    Sonnleitner, Andreas; Treder, Matthias Sebastian; Simon, Michael; Willmann, Sven; Ewald, Arne; Buchner, Axel; Schrauf, Michael

    2014-01-01

    Driver distraction is responsible for a substantial number of traffic accidents. This paper describes the impact of an auditory secondary task on drivers' mental states during a primary driving task. N=20 participants performed the test procedure in a car following task with repeated forced braking on a non-public test track. Performance measures (provoked reaction time to brake lights) and brain activity (EEG alpha spindles) were analyzed to describe distracted drivers. Further, a classification approach was used to investigate whether alpha spindles can predict drivers' mental states. Results show that reaction times and alpha spindle rate increased with time-on-task. Moreover, brake reaction times and alpha spindle rate were significantly higher while driving with auditory secondary task opposed to driving only. In single-trial classification, a combination of spindle parameters yielded a median classification error of about 8% in discriminating the distracted from the alert driving. Reduced driving performance (i.e., prolonged brake reaction times) during increased cognitive load is assumed to be indicated by EEG alpha spindles, enabling the quantification of driver distraction in experiments on public roads without verbally assessing the drivers' mental states. PMID:24144496

  19. The Effect of Mechanical Vibration Stimulation of Perception Subthreshold on the Muscle Force and Muscle Reaction Time of Lower Leg

    PubMed Central

    Kim, Huigyun; Kwak, Kiyoung; Kim, Dongwook

    2016-01-01

    The objective of this study is to investigate the effect of mechanical vibration stimulation on the muscle force and muscle reaction time of lower leg according to perception threshold and vibration frequency. A vibration stimulation with perception threshold intensity was applied on the Achilles tendon and tibialis anterior tendon. EMG measurement and analysis system were used to analyze the change of muscle force and muscle reaction time according to perception threshold and vibration frequency. A root-mean-square (RMS) value was extracted using analysis software and Maximum Voluntary Contraction (MVC) and Premotor Time (PMT) were analyzed. The measurement results showed that perception threshold was different from application sites of vibration frequency. Also, the muscle force and muscle reaction time showed difference according to the presence of vibration, frequency, and intensity. This result means that the vibration stimulation causes the change on the muscle force and muscle reaction time and affects the muscles of lower leg by the characteristics of vibration stimulation. PMID:27382244

  20. Estimating diffusivity along a reaction coordinate in the high friction limit: Insights on pulse times in laser-induced nucleation.

    PubMed

    Knott, Brandon C; Duff, Nathan; Doherty, Michael F; Peters, Baron

    2009-12-14

    In the high friction limit of Kramers' theory, the diffusion coefficient for motion along the reaction coordinate is a crucial parameter in determining reaction rates from mean first passage times. The Einstein relation between mean squared displacement, time, and diffusivity is inaccurate at short times because of ballistic motion and inaccurate at long times because trajectories drift away from maxima in the potential of mean force. Starting from the Smoluchowski equation for a downward parabolic barrier, we show how drift induced by the potential of mean force can be included in estimating the diffusivity. A modified relation between mean squared displacement, time, and diffusivity now also includes a dependence on the barrier curvature. The new relation provides the diffusivity at the top of the barrier from a linear regression that is analogous to the procedure commonly used with Einstein's relation. The new approach has particular advantages over previous approaches when evaluations of the reaction coordinate are costly or when the reaction coordinate cannot be differentiated to compute restraining forces or velocities. We use the new method to study the dynamics of barrier crossing in a Potts lattice gas model of nucleation from solution. Our analysis shows that some current hypotheses about laser-induced nucleation mechanisms lead to a nonzero threshold laser pulse duration below which a laser pulse will not affect nucleation. We therefore propose experiments that might be used to test these hypotheses. PMID:20001029

  1. Tonic and phasic activation and arousal effects as a function of feedback in repetitive-choice reaction time tasks.

    PubMed

    De Brabander, Bert; Declerck, Carolyn H; Boone, Christophe

    2002-06-01

    This study examines the effects of positive and negative feedback on performance during choice reaction time tasks to assess whether they differentially affect phasic arousal and tonic activation. Participants (N = 96) received either no feedback or signals of reward, punishment, or both during a semantic and a visuospatial repetitive-choice reaction time task. The number of errors made was analyzed both on a trial-by-trial basis and over a continuous series of 80 trials (assessing phasic and tonic feedback effects, respectively). The results show that punishment and reward have different phasic and tonic effects on performance. The data further show that feedback effects interact with the task characteristics: semantic versus visuospatial, and reaction stimulus preceded by a warning signal versus an irrelevant signal. The interaction effects appear to be consistent with the proposed neurological model.

  2. The effects of arm movement on reaction time in patients with latent and active upper trapezius myofascial trigger point

    PubMed Central

    Yassin, Marzieh; Talebian, Saeed; Ebrahimi Takamjani, Ismail; Maroufi, Nader; Ahmadi, Amir; Sarrafzadeh, Javad; Emrani, Anita

    2015-01-01

    Background: Myofascial pain syndrome is a significant source of mechanical pain. The aim of this study was to investigate the effects of arm movement on reaction time in females with latent and active upper trapezius myofascial trigger point. Methods: In this interventional study, a convenience sample of fifteen women with one active MTP, fifteen women with one latent MTP in the upper trapezius, and fifteen normal healthy women were participated. Participants were asked to stand for 10 seconds in an erect standing position. Muscle reaction times were recorded including anterior deltoid (AD), cervical paraspinal (CP) lumbar paraspinal (LP), both of upper trapezius (UT), sternocleidomastoid (SCM) and medial head of gastrocnemius (GcM). Participants were asked to flex their arms in response to a sound stimulus preceded by a warning sound stimulus. Data were analyzed using one-way ANOVA Test. Results: There was significant differences in motor time and reaction time between active and control groups (p< 0.05) except for GcM. There was no significant difference in motor time between active and passive groups except for UT without MTP and SCM (p< 0.05). Also, there were no significant differences in motor times between latent MTP and control groups. Furthermore, there was no significant difference in premotor times between the three groups. Conclusion: The present study shows that patients with active MTP need more time to react to stimulus, but patients with latent MTP are similar to healthy subjects in the reaction time. Patients with active MTP had less compatibility with environmental stimulations, and they responded to a specific stimulation with variability in Surface Electromyography (SEMG). PMID:26913258

  3. Real-time monitoring of single-molecule reactions in aqueous solution

    SciTech Connect

    Hong, Xiao; Xu, N.; Yeung, E.S. |

    1997-12-31

    Direct measurement of dynamics of single molecules, e.g., rhodamine 6G (R-6G) and single R-6G tagged with single biological molecules in aqueous solution, was achieved by using thin-layer laser-induced total internal reflection fluorescence microscopy (TLTIRFM). Single-molecule reactions can be directly and simultaneously monitored with spatial resolution down to 0.2 {mu}m and temporal resolution down to 0.2 ms. Dynamics of single-molecule reactions, for example, single dye molecules reacting with a proton and single proteins adsorbing on an active surface, are investigated and evident by monitoring their reaction environment, e.g., temperature and pH. Novel approaches and applications of these studies will be prospected in this presentation.

  4. Postexercise rehydration with beer impairs fluid retention, reaction time, and balance.

    PubMed

    Flores-Salamanca, Rebeca; Aragón-Vargas, Luis Fernando

    2014-10-01

    Beer is promoted by popular media as a good choice for rehydration, but there is limited support for the claim. To assess the effect of beer alcohol on rehydration and motor control, 11 young (24.4 ± 3.7 years old) males of legal drinking age were dehydrated to 2.12% ± 0.20% body mass (mean ± SD) by exercising in a climatic chamber (31.7 ± 1.6 °C, 55.0% ± 8.3% relative humidity) on 3 different days, 1 week apart, and rehydrated with 100% of their sweat loss using water (WATER), 4.6% alcohol beer (BEER), or low-alcohol beer (LAB), in random order. Urine output, blood alcohol content (BAC), reaction time (RT), and balance (as measured by center of pressure velocity (VCoP)) were measured every 30 min over 3 h and compared via 2-way, repeated-measures analyses of variance (ANOVAs). After consuming ≈1.6 L in 1 h, urine output was greater for BEER (1218 ± 279 mL) than for LAB (745 ± 313 mL, p = 0.007) and WATER (774 ± 304 mL, p = 0.043). BAC remained at 0 with WATER and LAB; with BEER, BAC reached 0.857 g/L (95% confidence intervals [0.752, 0.963]) immediately postrehydration. RT was longer for BEER (0.314 ± 0.039 s) than for LAB (0.294 ± 0.034 s, p = 0.009), but was no different from WATER (0.293 ± 0.049 s, p = 0.077). VCoPx was significantly higher for BEER (0.0284 ± 0.0020 m/s) compared with LAB (0.0233 ± 0.0010 m/s) or WATER (0.0238 ± 0.0010 m/s) (p = 0.022), but VCoPy was not different among beverages. In conclusion, rehydration with BEER resulted in higher diuresis, slower RT, and impaired VCoP than rehydration with LAB or WATER. PMID:25041559

  5. Postexercise rehydration with beer impairs fluid retention, reaction time, and balance.

    PubMed

    Flores-Salamanca, Rebeca; Aragón-Vargas, Luis Fernando

    2014-10-01

    Beer is promoted by popular media as a good choice for rehydration, but there is limited support for the claim. To assess the effect of beer alcohol on rehydration and motor control, 11 young (24.4 ± 3.7 years old) males of legal drinking age were dehydrated to 2.12% ± 0.20% body mass (mean ± SD) by exercising in a climatic chamber (31.7 ± 1.6 °C, 55.0% ± 8.3% relative humidity) on 3 different days, 1 week apart, and rehydrated with 100% of their sweat loss using water (WATER), 4.6% alcohol beer (BEER), or low-alcohol beer (LAB), in random order. Urine output, blood alcohol content (BAC), reaction time (RT), and balance (as measured by center of pressure velocity (VCoP)) were measured every 30 min over 3 h and compared via 2-way, repeated-measures analyses of variance (ANOVAs). After consuming ≈1.6 L in 1 h, urine output was greater for BEER (1218 ± 279 mL) than for LAB (745 ± 313 mL, p = 0.007) and WATER (774 ± 304 mL, p = 0.043). BAC remained at 0 with WATER and LAB; with BEER, BAC reached 0.857 g/L (95% confidence intervals [0.752, 0.963]) immediately postrehydration. RT was longer for BEER (0.314 ± 0.039 s) than for LAB (0.294 ± 0.034 s, p = 0.009), but was no different from WATER (0.293 ± 0.049 s, p = 0.077). VCoPx was significantly higher for BEER (0.0284 ± 0.0020 m/s) compared with LAB (0.0233 ± 0.0010 m/s) or WATER (0.0238 ± 0.0010 m/s) (p = 0.022), but VCoPy was not different among beverages. In conclusion, rehydration with BEER resulted in higher diuresis, slower RT, and impaired VCoP than rehydration with LAB or WATER.

  6. Amygdala fMRI Signal as a Predictor of Reaction Time

    PubMed Central

    Riedel, Philipp; Jacob, Mark J.; Müller, Dirk K.; Vetter, Nora C.; Smolka, Michael N.; Marxen, Michael

    2016-01-01

    Reaction times (RTs) are a valuable measure for assessing cognitive processes. However, RTs are susceptible to confounds and therefore variable. Exposure to threat, for example, speeds up or slows down responses. Distinct task types to some extent account for differential effects of threat on RTs. But also do inter-individual differences like trait anxiety. In this functional magnetic resonance imaging (fMRI) study, we investigated whether activation within the amygdala, a brain region closely linked to the processing of threat, may also function as a predictor of RTs, similar to trait anxiety scores. After threat conditioning by means of aversive electric shocks, 45 participants performed a choice RT task during alternating 30 s blocks in the presence of the threat conditioned stimulus [CS+] or of the safe control stimulus [CS-]. Trait anxiety was assessed with the State-Trait Anxiety Inventory and participants were median split into a high- and a low-anxiety subgroup. We tested three hypotheses: (1) RTs will be faster during the exposure to threat compared to the safe condition in individuals with high trait anxiety. (2) The amygdala fMRI signal will be higher in the threat condition compared to the safe condition. (3) Amygdala fMRI signal prior to a RT trial will be correlated with the corresponding RT. We found that, the high-anxious subgroup showed faster responses in the threat condition compared to the safe condition, while the low-anxious subgroup showed no significant difference in RTs in the threat condition compared to the safe condition. Though the fMRI analysis did not reveal an effect of condition on amygdala activity, we found a trial-by-trial correlation between blood-oxygen-level-dependent signal within the right amygdala prior to the CRT task and the subsequent RT. Taken together, the results of this study showed that exposure to threat modulates task performance. This modulation is influenced by personality trait. Additionally and most

  7. Detection of Food Hazards in Foods: Comparison of Real Time Polymerase Chain Reaction and Cultural Methods

    PubMed Central

    Bonilauri, Paolo; Bardasi, Lia; Leonelli, Roberto; Ramini, Mattia; Luppi, Andrea; Merialdi, Giuseppe

    2016-01-01

    Foodstuffs should not contain microorganisms or their toxins or metabolites in quantities suggesting an unacceptable risk for human health. The detection of food hazards in foods is performed by several tests that produce results dependent on the analytical method used: an analytical reference method, defined as standard, is associated with each microbiological criterion laid down in Regulation 2073/2005/EC, but, analytical methods other than the reference ones, in particular more rapid methods, could be used. Combined screening methods performed by real time-polymerase chain reaction (RT-PCR) are currently validated as alternative methods according to the ISO 16140:2003 and certified by the Association Française de Normalisation. However, the positive results obtained with these alternative methods, the investigated molecular relations that resulted positive have to be confirmed with cultural methods using the same enrichment media in which the molecular screening was performed. Since it is necessary to assess if these testing schemes provide equivalent guarantees of food safety, the aim of this retrospective study is to analyse the data collected, from 2012 to 2014 by Emilia Romagna Region in the field of Piano Regionale Alimenti (Food Regional Plan) during official controls monitoring food samples of animal and other than animal origin. Records performed by combined methods of molecular screening of Salmonella spp., Listeria monocytogenes and thermophilic Campylobacter and cultural confirmation results were gathered together and the results were compared in order to assess the sensitivity of the methods. A total of 10,604 food samples were considered in this study: the comparison of the data revealed that the RT-PCR method detected Salmonella, L. monocytogenes, and thermophilic Campylobacter in 2.18, 3.85 and 3.73% of the samples, respectively, whereas by using cultural method these pathogens were isolated in 0.43, 1.57 and 1.57% of samples, respectively. In

  8. Time-Resolved Structural Analysis of Cation Exchange Reactions in Birnessite Using Synchrotron XRD

    NASA Astrophysics Data System (ADS)

    Lopano, C. L.; Heaney, P. J.; Post, J. E.; Hanson, J. C.; Lee, Y.; Komarneni, S.

    2002-12-01

    Birnessite ((Na,Ca,Mn2+) Mn7O142.8H2O) is a layered Mn-oxide with a 7.2Å spacing between the Mn octahedral sheets. Since birnessite is an abundant phase in soils, desert varnishes, and ocean nodules, it plays a significant role in soil and groundwater chemistry. Experiments by Golden et al. (1986,1987) have demonstrated that Na-buserite (hydrated birnessite) readily exchanges Na+ for a variety of other cations, including K+, Mg2+, Ca2+, Ba2+, Ni2+, and Sr2+. In light of its high cation exchange capacity, birnessite is industrially important for ion and molecular sieves and cathodic materials. In addition, birnessite serves as a precursor in the synthesis of todorokite, which has a 3x3 tunnel structure and is used as an octahedral sieve. We monitored cation-exchange reactions in birnessite by time-resolved X-ray powder diffraction with a simple flow-through cell at the National Synchrotron Light Source. The flow-through cell was developed by Lee and Parise at SUNY-Stony Brook, and this work represents its first application to Mn oxides. A series of synthetic Na-birnessite samples were saturated with chloride solutions containing dissolved K+, Mg2+, and Ba2+, ranging from 0.1M to 0.001M. Powder X-ray diffraction patterns were collected every ~ 3 minutes. The synchrotron experiments revealed that complete cation exchange occurs within three hours, and significant modifications of the arrangements of interlayer cations and water molecules accompany the exchange. Specifically, the replacement of Na by Mg resulted in the continuous growth of a discrete buserite-like phase with a 10Å layer spacing, while replacement of Na by K and Ba retained the 7Å spacing. K replacement of Na resulted in gradually decreasing peak intensity and peak merging. The Ba exchange yielded an abrupt decrease in diffraction intensities followed by a more gradual lattice change over the last 2 hours. Rietveld analysis led to the first determination of the structure of Ba-birnessite in space

  9. Speech Planning Happens before Speech Execution: Online Reaction Time Methods in the Study of Apraxia of Speech

    ERIC Educational Resources Information Center

    Maas, Edwin; Mailend, Marja-Liisa

    2012-01-01

    Purpose: The purpose of this article is to present an argument for the use of online reaction time (RT) methods to the study of apraxia of speech (AOS) and to review the existing small literature in this area and the contributions it has made to our fundamental understanding of speech planning (deficits) in AOS. Method: Following a brief…

  10. Effects of Age, Intelligence and Executive Control Function on Saccadic Reaction Time in Persons with Intellectual Disabilities

    ERIC Educational Resources Information Center

    Haishi, Koichi; Okuzumi, Hideyuki; Kokubun, Mitsuru

    2011-01-01

    The current research aimed to clarify the influence of age, intelligence and executive control function on the central tendency and intraindividual variability of saccadic reaction time in persons with intellectual disabilities. Participants were 44 persons with intellectual disabilities aged between 13 and 57 years whose IQs were between 14 and…

  11. [THE HIGHLY EFFECTIVE DETECTION OF DNA RICKETTSIA USING TECHNIQUE OF POLYMERASE CHAIN REACTION IN REAL-TIME].

    PubMed

    Kartashov, M Yu; Mikryukova, T P; Ternovoi, V A; Moskvitina, N S; Loktev, V B

    2015-12-01

    The article considers development of highly effective technique of detection of genetic material of ricketsia based on polymerase chain reaction in real-time using original primers to the most conservative sites of gene of citrate synthase (gItA). The analytical sensitivity of the developed polymerase chain reaction in real-time test permits to detect from 80 genome equivalents in analyzed sample during three hours. The high specificity of test-system is substantiated by detection of nucleotide sequences of amplificated fragments of gene gltA. The approbation ofthe polymerase chain reaction in real-time test is carried out on collection of 310 ticks of species I. persulcatus, I. pavlovskyi, D. reticulatus. It is demonstrated that the developed alternate ofprimers and probe permits with high degree of sensitivity and specifcity to detect DNA of different species of ricketsia widespread on territory of Russia (R. sibirica, R. raoultii, R. helvetica, R. tarasevichiae). The proposed polymerase chain reaction in real-time test can be appliedfor isolation of fragment of gene gltA with purpose for detecting nucleotide sequence and subsequent genetic typing of ricketsia. The application ofthe proposed technique can facilitate task of monitoring hot spots of ricketsiosis.

  12. Persistence of the Intuitive Conception That Heavier Objects Sink More: A Reaction Time Study with Different Levels of Interference

    ERIC Educational Resources Information Center

    Potvin, Patrice; Masson, Steve; Lafortune, Stéphanie; Cyr, Guillaume

    2015-01-01

    Recent research efforts have argued for the "persistence" of some of students' frequent scientific misconceptions, even after correct answers are produced. Some of these studies, based on the analysis of reaction times, have recorded latencies for counter-intuitive or incongruent stimuli compared to intuitive or congruent ones. The…

  13. The Interaction of Extraversion, Neuroticism, and Audience Presence in the Performance of a Choice Reaction Time Task.

    ERIC Educational Resources Information Center

    Calcote, Lynn G.

    Ninety-six female introductory psychology students differing in terms of the dimensions of neuroticism-stability and introversion-extraversion performed two sets of thirty trials each on a choice reaction time task. On one of the sets of trials the Ss were observed by two female observers and on the other set of trials the observers were not…

  14. The Fixed-Links Model in Combination with the Polynomial Function as a Tool for Investigating Choice Reaction Time Data

    ERIC Educational Resources Information Center

    Schweizer, Karl

    2006-01-01

    A model with fixed relations between manifest and latent variables is presented for investigating choice reaction time data. The numbers for fixation originate from the polynomial function. Two options are considered: the component-based (1 latent variable for each component of the polynomial function) and composite-based options (1 latent…

  15. Demonstration of Nondeclarative Sequence Learning in Mice: Development of an Animal Analog of the Human Serial Reaction Time Task

    ERIC Educational Resources Information Center

    Christie, Michael A.; Hersch, Steven M.

    2004-01-01

    In this paper, we demonstrate nondeclarative sequence learning in mice using an animal analog of the human serial reaction time task (SRT) that uses a within-group comparison of behavior in response to a repeating sequence versus a random sequence. Ten female B6CBA mice performed eleven 96-trial sessions containing 24 repetitions of a 4-trial…

  16. Reaction Time of Facial Affect Recognition in Asperger's Disorder for Cartoon and Real, Static and Moving Faces

    ERIC Educational Resources Information Center

    Miyahara, Motohide; Bray, Anne; Tsujii, Masatsugu; Fujita, Chikako; Sugiyama, Toshiro

    2007-01-01

    This study used a choice reaction-time paradigm to test the perceived impairment of facial affect recognition in Asperger's disorder. Twenty teenagers with Asperger's disorder and 20 controls were compared with respect to the latency and accuracy of response to happy or disgusted facial expressions, presented in cartoon or real images and in…

  17. Contribution of Temporal Preparation and Processing Speed to Simple Reaction Time in Persons with Alzheimer's Disease and Mild Cognitive Impairment

    ERIC Educational Resources Information Center

    Sylvain-Roy, Stephanie; Bherer, Louis; Belleville, Sylvie

    2010-01-01

    Temporal preparation was assessed in 15 Alzheimer's disease (AD) patients, 20 persons with mild cognitive impairment (MCI) and 28 healthy older adults. Participants completed a simple reaction time task in which the preparatory interval duration varied randomly within two blocks (short versus long temporal window). Results indicated that AD and…

  18. Evaluation of a multiplex real-time polymerase chain reaction assay for the detection of influenza and respiratory syncytial viruses.

    PubMed

    Esposito, Susanna; Scala, Alessia; Tagliabue, Claudia; Zampiero, Alberto; Bianchini, Sonia; Principi, Nicola

    2016-01-01

    Nasopharyngeal swabs from 424 children were used to compare the performances of the new multiplex real-time polymerase chain reaction (RT-PCR) RIDA®GENE Flu & RSV kit and monospecific RT-PCR assays in detecting respiratory syncytial and influenza viruses. The easy-to-use kit was highly sensitive and specific and is recommended for routine practice.

  19. OSP Parameters and the Cognitive Component of Reaction Time to a Missing Stimulus: Linking Brain and Behavior

    ERIC Educational Resources Information Center

    Hernandez, Oscar H.; Vogel-Sprott, Muriel

    2009-01-01

    This within-subjects experiment tested the relationship between the premotor (cognitive) component of reaction time (RT) to a missing stimulus and parameters of the omitted stimulus potential (OSP) brain wave. Healthy young men (N = 28) completed trials with an auditory stimulus that recurred at 2 s intervals and ceased unpredictably. Premotor RT…

  20. Simple and choice reaction-time performance following occlusion of the anterior cerebral arteries in the rat.

    PubMed

    Ward, N M; Sharkey, J; Marston, H M; Brown, V J

    1998-12-01

    Focal cerebral ischemia in the rat has traditionally been studied by examining the consequences of middle-cerebral artery occlusion. However, the anteriorcerebral arteries of the rat may now also be bilaterally occluded by stereotaxic injection of the vasoconstrictor endothelin-1, resulting in ischemic damage to medial prefrontal cortex and the anteromedial basal forebrain. The behavioural consequences of anterior-cerebral artery occlusion (ACAo) were studied in two experiments using simple and choice reaction-time tasks designed to dissociate response impairments from dysfunction of motivation and attention, respectively. Following ACAo, reaction-time increased post-surgery in the choice, but not simple reaction-time task. There was also an increase in incorrect choices in the choice reaction-time task. However, the impairments were independent of motivational or attentional function, which remained intact. Although the ACAo-induced ischemic damage did not disrupt motivation or attention, the results suggest that the lesion results in an executive impairment in selecting and initiating responses.

  1. Mass Reaction Time Measurement of the Speed of the Nerve Impulse and the Duration of Mental Processes in Class

    ERIC Educational Resources Information Center

    Rozin, Paul; Jonides, John

    1977-01-01

    Described is an in-class demonstration of mass reaction time which measures the speed of nerve impulses and the duration of various cognitive processes. A simpler version of the experiment for at-home use is described. (Author/DB)

  2. A Tutorial for Analyzing Human Reaction Times: How to Filter Data, Manage Missing Values, and Choose a Statistical Model

    ERIC Educational Resources Information Center

    Lachaud, Christian Michel; Renaud, Olivier

    2011-01-01

    This tutorial for the statistical processing of reaction times collected through a repeated-measure design is addressed to researchers in psychology. It aims at making explicit some important methodological issues, at orienting researchers to the existing solutions, and at providing them some evaluation tools for choosing the most robust and…

  3. Accurate Time-Dependent Wave Packet Calculations for the O(+) + H2 → OH(+) + H Ion-Molecule Reaction.

    PubMed

    Bulut, N; Castillo, J F; Jambrina, P G; Kłos, J; Roncero, O; Aoiz, F J; Bañares, L

    2015-12-17

    Accurate quantum reactive scattering time-dependent wave packet close-coupling calculations have been carried out to determine total reaction probabilities and integral cross sections for the O(+) + H2 → OH(+) + H reaction in a range of collision energies from 10(-3) eV up to 1.0 eV for the H2 rovibrational states (v = 0; j = 0, 1, 2) and (v = 1; j = 0) using the potential energy surface (PES) by Martı́nez et al. As expected for a barrierless reaction, the reaction cross section decays rapidly with collision energy, Ec, following a behavior that nearly corresponds to that predicted by the Langevin model. Rotational excitation of H2 into j = 1, 2 has a very moderate effect on reactivity, similarly to what happens with vibrational excitation below Ec ≈ 0.3 eV. However, at higher collision energies the cross section increases notably when H2 is promoted to v = 1. This effect is explained by resorting to the effective potentials in the entrance channel. The integral cross sections have been used to calculate rate constants in the temperature range 200-1000 K. A good overall agreement has been found with the available experimental data on integral cross sections and rate constants. In addition, time-independent quantum mechanical and quasi-classical trajectory (QCT) calculations have been performed on the same PES aimed to compare the various methodologies and to discern the detailed mechanism of the title reaction. In particular, the analysis of individual trajectories has made it possible to explain, in terms of the coupling between reagent relative velocity and the topography of the PES, the presence of a series of alternating maxima and minima in the collision energy dependence of the QCT reaction probabilities for the reactions with H2(v=0,1,j=0), which are absent in the quantum mechanical calculations.

  4. Time Out: The Viewing Experience and Reactions to the 1987 NFL Players' Strike.

    ERIC Educational Resources Information Center

    Walker, James R.

    The 1987 NFL players' strike provided an opportunity to evaluate the importance of media gratification and viewing involvement in the development of audience reactions to a major sports labor conflict that produced gratification denial. Two groups of viewers of professional football--183 adult males in the Memphis, Tennessee area, interviewed by…

  5. General model of a cascade of reactions with time delays: Global stability analysis

    NASA Astrophysics Data System (ADS)

    Bodnar, Marek

    2015-07-01

    The problem considered in this paper consists of a cascade of reactions with discrete as well as distributed delays, which arose in the context of Hes1 gene expression. For the abstract general model sufficient conditions for global stability are presented. Then the abstract result is applied to the Hes1 model.

  6. Stability analysis in a car-following model with reaction-time delay and delayed feedback control

    NASA Astrophysics Data System (ADS)

    Jin, Yanfei; Xu, Meng

    2016-10-01

    The delayed feedback control in terms of both headway and velocity differences has been proposed to guarantee the stability of a car-following model including the reaction-time delay of drivers. Using Laplace transformation and transfer function, the stable condition is derived and appropriate choices of time delay and feedback gains are designed to stabilize traffic flow. Meanwhile, an upper bound on explicit time delay is determined with respect to the response of desired acceleration. To ensure the string stability, the explicit time delay cannot over its upper bound. Numerical simulations indicate that the proposed control method can restraint traffic congestion and improve control performance.

  7. Graphic analysis of relaxation times of enzyme-catalysed reactions. An extension of the graphic method of King and Altman.

    PubMed Central

    Zhao, M

    1992-01-01

    An extension of the graphic method of King & Altman (1956) (J. Phys. Chem. 60, 1375-1378) is applied to the analysis of relaxation times of enzyme-catalysed reactions and a simple graphic method is presented. Clear-cut graphs, simple drawing, easy operation (without the need to perform the usual complex mathematical operations), and reliable results are the main characteristics of this kind of graphic method. A system of enzyme-catalysed reactions (E <--> ES <--> EP) is used as the actual example for illustrating the graphic method. PMID:1445198

  8. Comparison of Nested Polymerase Chain Reaction and Real-Time Polymerase Chain Reaction with Parasitological Methods for Detection of Strongyloides stercoralis in Human Fecal Samples.

    PubMed

    Sharifdini, Meysam; Mirhendi, Hossein; Ashrafi, Keyhan; Hosseini, Mostafa; Mohebali, Mehdi; Khodadadi, Hossein; Kia, Eshrat Beigom

    2015-12-01

    This study was performed to evaluate nested polymerase chain reaction (PCR) and real-time PCR methods for detection of Strongyloides stercoralis in fecal samples compared with parasitological methods. A total of 466 stool samples were examined by conventional parasitological methods (formalin ether concentration [FEC] and agar plate culture [APC]). DNA was extracted using an in-house method, and mitochondrial cytochrome c oxidase subunit 1 and 18S ribosomal genes were amplified by nested PCR and real-time PCR, respectively. Among 466 samples, 12.7% and 18.2% were found infected with S. stercoralis by FEC and APC, respectively. DNA of S. stercoralis was detected in 18.9% and 25.1% of samples by real-time PCR and nested PCR, respectively. Considering parasitological methods as the diagnostic gold standard, the sensitivity and specificity of nested PCR were 100% and 91.6%, respectively, and that of real-time PCR were 84.7% and 95.8%, respectively. However, considering sequence analyzes of the selected nested PCR products, the specificity of nested PCR is increased. In general, molecular methods were superior to parasitological methods. They were more sensitive and more reliable in detection of S. stercoralis in comparison with parasitological methods. Between the two molecular methods, the sensitivity of nested PCR was higher than real-time PCR.

  9. Experimental disentangling of spatial-compatibility and interhemispheric-relay effects in simple reaction time (Poffenberger paradigm).

    PubMed

    Braun, Claude M J; Larocque, Caroline; Achim, André

    2004-08-01

    Spatial-compatibility effects can be obtained in simple reaction time (SRT) provided that spatially distinct responses are frequently required. Since this effect is limited to trials with relatively long reaction times (RTs), Hommel (1996b) proposed that if the response does not occur shortly after stimulus detection, then the spatial code of the stimulus can interfere with that of the response. A series of experiments is reported showing that (a) spatial compatibility in SRT to lateralized stimuli is not an alternative, but rather a complementary, explanation to interhemispheric transfer time (contrary to what Hommel surmised), and (b) the spatial compatibility component is essentially limited to the first trial after shifting response preparation from one-half of the visual fields to the other, suggesting a mechanism akin to an orienting response.

  10. Optimization of 6-carboxy-X-rhodamine concentration for real-time polymerase chain reaction using molecular beacon chemistry.

    PubMed

    Wang, Gehua; Becker, Erin; Mesa, Christine

    2007-03-01

    The optimal 6-carboxy-X-rhodamine (ROX) concentration, which is used as a passive reference dye for real-time quantitative polymerase chain reaction (PCR) with molecular beacon chemistry, was determined with the Mx4000 Multiplex Quantitative PCR System. Additionally, the effects of changing ROX concentrations on PCR reproducibility, Ct values, and efficiency were investigated with this system by using the PCR data obtained from amplification of the Escherichia coli shiga toxin 2 (stx2) gene and the Campylobacter jejuni luxS gene. This study indicated that different ROX concentrations influence many aspects of the real-time PCR reaction. ROX concentration variation could have consequences in the analysis of quantitative data and may lead to erroneous results. This study further indicated that the optimal ROX concentration is 60 nmol/L for real-time PCR, using molecular beacon chemistry for PCR assay of luxS and stx2 genes.

  11. Directional errors of movements and their correction in a discrete tracking task. [pilot reaction time and sensorimotor performance

    NASA Technical Reports Server (NTRS)

    Jaeger, R. J.; Agarwal, G. C.; Gottlieb, G. L.

    1978-01-01

    Subjects can correct their own errors of movement more quickly than they can react to external stimuli by using three general categories of feedback: (1) knowledge of results, primarily visually mediated; (2) proprioceptive or kinaesthetic such as from muscle spindles and joint receptors, and (3) corollary discharge or efference copy within the central nervous system. The effects of these feedbacks on simple reaction time, choice reaction time, and error correction time were studied in four normal human subjects. The movement used was plantarflexion and dorsiflexion of the ankle joint. The feedback loops were modified, by changing the sign of the visual display to alter the subject's perception of results, and by applying vibration at 100 Hz simultaneously to both the agonist and antagonist muscles of the ankle joint. The central processing was interfered with when the subjects were given moderate doses of alcohol (blood alcohol concentration levels of up to 0.07%). Vibration and alcohol increase both the simple and choice reaction times but not the error correction time.

  12. A practical approach to calculate the time evolutions of magnetic field effects on photochemical reactions in nano-structured materials.

    PubMed

    Yago, Tomoaki; Wakasa, Masanobu

    2015-04-21

    A practical method to calculate time evolutions of magnetic field effects (MFEs) on photochemical reactions involving radical pairs is developed on the basis of the theory of the chemically induced dynamic spin polarization proposed by Pedersen and Freed. In theory, the stochastic Liouville equation (SLE), including the spin Hamiltonian, diffusion motions of the radical pair, chemical reactions, and spin relaxations, is solved by using the Laplace and the inverse Laplace transformation technique. In our practical approach, time evolutions of the MFEs are successfully calculated by applying the Miller-Guy method instead of the final value theorem to the inverse Laplace transformation process. Especially, the SLE calculations are completed in a short time when the radical pair dynamics can be described by the chemical kinetics consisting of diffusions, reactions and spin relaxations. The SLE analysis with a short calculation time enables one to examine the various parameter sets for fitting the experimental date. Our study demonstrates that simultaneous fitting of the time evolution of the MFE and of the magnetic field dependence of the MFE provides valuable information on the diffusion motions of the radical pairs in nano-structured materials such as micelles where the lifetimes of radical pairs are longer than hundreds of nano-seconds and the magnetic field dependence of the spin relaxations play a major role for the generation of the MFE.

  13. Real-time trace detection and identification of chemical warfare agent simulants using recent advances in proton transfer reaction time-of-flight mass spectrometry.

    PubMed

    Petersson, Fredrik; Sulzer, Philipp; Mayhew, Chris A; Watts, Peter; Jordan, Alfons; Märk, Lukas; Märk, Tilmann D

    2009-12-01

    This work demonstrates for the first time the potential of using recent developments in proton transfer reaction mass spectrometry for the rapid detection and identification of chemical warfare agents (CWAs) in real-time. A high-resolution (m/Deltam up to 8000) and high-sensitivity (approximately 50 cps/ppbv) proton transfer reaction time-of-flight mass spectrometer (PTR-TOF 8000 from Ionicon Analytik GmBH) has been successfully used to detect a number of CWA simulants at room temperature; namely dimethyl methylphosphonate, diethyl methylphosphonate, diisopropyl methylphosphonate, dipropylene glycol monomethyl ether and 2-chloroethyl ethyl sulfide. Importantly, we demonstrate in this paper the potential to identify CWAs with a high level of confidence in complex chemical environments, where multiple threat agents and interferents could also be present in trace amounts, thereby reducing the risk of false positives. Instantaneous detection and identification of trace quantities of chemical threats using proton transfer reaction mass spectrometry could form the basis for a timely warning system capability with greater precision and accuracy than is currently provided by existing analytical technologies.

  14. Comparative quantitative analysis of 14 types of human papillomavirus by real-time polymerase chain reaction monitoring Invader reaction (Q-Invader assay).

    PubMed

    Tadokoro, Kenichi; Akutsu, Yuki; Tanaka, Kazuya; Saito, Tsuyoshi; Yamaguchi, Toshikazu; Egashira, Toru; Ishiwata, Isamu; Hara, Takashi

    2010-01-01

    Human papillomavirus (HPV) is associated with several cervical diseases. A simple, rapid, cost-effective assay for identifying viral genotypes would greatly aid efforts for early detection and disease prevention. A real-time polymerase chain reaction monitoring Invader reaction assay (Q-Invader assay) was developed for genotyping and comparative quantitative analysis of 14 high-risk HPV genotypes (16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, 67, and 68). A total of 131 cervical samples containing HPV in Japan were examined by Q-Invader assay, and the results were compared with those from sequencing with consensus and genotype-specific primers. Genotypes determined by Q-Invader agreed with those of sequencing in all samples. Coinfections with multiple high-risk genotypes were correctly identified by Q-Invader assay in 27 samples. In addition, the relative ratios of the genotypes were determined. Thus, Q-Invader assay is a useful tool for genotyping and comparative quantitative analysis of high-risk HPV types. PMID:19733028

  15. Studying Chemical Reactions, One Bond at a Time, with Single Molecule AFM Techniques

    NASA Astrophysics Data System (ADS)

    Fernandez, Julio M.

    2008-03-01

    The mechanisms by which mechanical forces regulate the kinetics of a chemical reaction are unknown. In my lecture I will demonstrate how we use single molecule force-clamp spectroscopy and protein engineering to study the effect of force on the kinetics of thiol/disulfide exchange. Reduction of disulfide bond via the thiol/disulfide exchange chemical reaction is crucial in regulating protein function and is of common occurrence in mechanically stressed proteins. While reduction is thought to proceed through a substitution nucleophilic bimolecular (SN2) reaction, the role of a mechanical force in modulating this chemical reaction is unknown. We apply a constant stretching force to single engineered disulfide bonds and measure their rate of reduction by dithiothreitol (DTT). We find that while the reduction rate is linearly dependent on the concentration of DTT, it is exponentially dependent on the applied force, increasing 10-fold over a 300 pN range. This result predicts that the disulfide bond lengthens by 0.34 å at the transition state of the thiol/disulfide exchange reaction. In addition to DTT, we also study the reduction of the engineered disulfide bond by the E. coli enzyme thioredoxin (Trx). Thioredoxins are enzymes that catalyze disulfide bond reduction in all organisms. As before, we apply a mechanical force in the range of 25-450 pN to the engineered disulfide bond substrate and monitor the reduction of these bonds by individual enzymes. In sharp contrast with the data obtained with DTT, we now observe two alternative forms of the catalytic reaction, the first requiring a reorientation of the substrate disulfide bond, causing a shortening of the substrate polypeptide by 0.76±0.07 å, and the second elongating the substrate disulfide bond by 0.21±0.01 å. These results support the view that the Trx active site regulates the geometry of the participating sulfur atoms, with sub-ångström precision, in order to achieve efficient catalysis. Single molecule

  16. Real-Time Measurement Of Polyurethane Foam Reactions And Hydrogen-Bonding By FT-IR Spectroscopy

    NASA Astrophysics Data System (ADS)

    Davis, Bradley L.; Harthcock, Matthew A.; Christenson, C. P.; Turner, R. B.

    1989-12-01

    The reaction and hydrogen-bond formation kinetics which occur in polyurethane foams will have an ultimate effect on the properties of these materials. Measurement of several urethane and urea carbonyl absorptions (free and hydrogen-bonded) provides two important pieces of information: (1) the chemical reactions which occur and (2) the progression of hydrogen-bond formation after reaction has completed. An attenuated total reflectance (ATR) Fourier-transform infrared spectroscopic technique has been previously developed which allows real-time data to be obtained during the foaming reaction 1,2. The authors have adapted a similar system to studying foams in order to more quantitatively interpret the real-time data in terms of the complex hydrogen-bonding structure. The vibrational assignments used for the carbonyl region of polyurethane foam spectra are as follows: 1732 cm-1 free urethane 1712 free urea 1701 ordered hydrogen-bonded urethane 1699-1653 monodentate hydrogen-bonded urea (Fig. 1) 1641 bidentate/ordered hydrogen-bonded urea. (Fig. 1)

  17. The Impact of Hypnotic Suggestions on Reaction Times in Continuous Performance Test in Adults with ADHD and Healthy Controls

    PubMed Central

    Virta, Maarit; Hiltunen, Seppo; Mattsson, Markus; Kallio, Sakari

    2015-01-01

    Attention is one of the key factors in both hypnotic processes and patients with ADHD. In addition, the brain areas associated with hypnosis and ADHD overlap in many respects. However, the use of hypnosis in ADHD patients has still received only minor attention in research. The main purpose of the present work was to investigate whether hypnosis and hypnotic suggestions influence the performance of adult ADHD (n = 27) and control participants (n = 31) in the continuous performance test (CPT). The hypnotic susceptibility of the participants was measured by the Harvard Group Scale of Hypnotic Susceptibility (HGSHS:A) and the attentional task was a three minute long auditory version of the CPT. The CPT task was administered four times: before hypnosis (CPT1), after a hypnotic induction (CPT2), after suggestions about speed and accuracy (CPT3), and after the termination of hypnosis (CPT4). The susceptibility of the groups measured by HGSHS:A did not differ. There was a statistically significant decrease in reaction times in both ADHD and control groups between CPT2 and CPT3. The differences between CPT1 and CPT2, even though non-significant, were different in the two groups: in the ADHD group reaction times decreased whereas in the control group they increased. Both groups made very few errors in the short CPT. This study indicates that hypnotic suggestions have an effect on reaction times in the sustained attention task both in adult ADHD patients and control subjects. The theoretical and clinical implications are discussed. PMID:25962151

  18. Surface pump-probe femtosecond-laser mass spectrometry: Time-, mass-, and velocity-resolved detection of surface reaction dynamics

    SciTech Connect

    Vaida, Mihai E.; Bernhardt, Thorsten M.

    2010-10-15

    A detailed account of the experimental methodology of surface pump-probe femtosecond-laser mass spectrometry is presented. This recently introduced technique enables the direct time-resolved investigation of surface reaction dynamics by monitoring the mass and the relative velocity of intermediates and products of a photoinduced surface reaction via multiphoton ionization. As a model system, the photodissociation dynamics of methyl iodide adsorbed at submonolayer coverage on magnesia ultrathin films is investigated. The magnesia surface preparation and characterization as well as the pulsed deposition of methyl iodide are described. The femtosecond-laser excitation (pump) and, in particular, the resonant multiphoton ionization surface detection (probe) schemas are discussed in detail. Results of pump-probe time-resolved methyl and iodine atom detection experiments are presented and the potential of this method for velocity-resolved photofragment analysis is evaluated.

  19. Recognition accuracy and reaction time of vocal expressions of emotion by African-American and Euro-American college women.

    PubMed

    Weathers, Monica D; Kitsantas, Panagiota; Lever, Teresa; O'Brien, Patrick; Campbell, Stacy; Rastatter, Michael

    2004-10-01

    This study examined the relationship of racial group membership and vocal expressions of emotion. Recognition accuracy and reaction time were examined using the Diagnostic Assessment of Nonverbal Accuracy 2 Receptive Paralanguage subtests with 18 young Euro-American and African-American women. Participants listened to Euro-American children and adults speaking a neutral sentence, and identified the emotion as happy, sad, angry, or fearful. Analysis identified a significant effect for race on reaction time. Euro-American participants had faster mean RT than the African-American women for the recognition of vocal expression of emotion portrayed by Euro-Americans. However, no significant differences were found in mean accurate identification between the two groups. The finding of a significant difference in recognition RT but not in accuracy between the stimuli spoken by an adult and a child was unexpected. Both racial groups had faster mean RT in response to vocal expression of emotion by children. PMID:15560358

  20. Design, simulation and application of a new micromixing device for time resolved infrared spectroscopy of chemical reactions in solution.

    PubMed

    Hinsmann, P; Frank, J; Svasek, P; Harasek, M; Lendl, B

    2001-09-01

    We present a novel micromachined fast diffusion based mixing unit for the study of rapid chemical reactions in solution with stopped-flow time resolved Fourier transform infrared spectroscopy (TR-FTIR). The presented approach is based on a chip for achieving lamination of two liquid sheets of 10 microm thickness and approximately 1 mm width on top of each other and operation in the stopped-flow mode. The microstructure is made on infrared transmitting calcium fluoride discs and built up with two epoxy negative photoresist layers and one silver layer in between. Due to the highly laminar flow conditions and the short residence time in the mixer there is hardly any mixing when the two liquid streamlines pass through the mixing unit, which allows one to record a mid-IR transmission spectrum of the analytes prior to reaction. When the flow is stopped, the reactant streams are arrested in the flow-cell and rapidly mixed by diffusion due to the reduced interstream distances and the reaction can be directly followed with hardly any dead time. On the basis of two model reactions-neutralisation of acetic acid with sodium hydroxide as well as saponification of methyl monochloroacetate-the performance of the mixing device was tested revealing proper functioning of the device with a time for complete mixing of less than 100 ms. The experimental results were supported by numerical simulations using computational fluid dynamics (CFD), which allowed a reliable, quantitative analysis of concentration, pressure and flow profiles in the course of the mixing process.