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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

    ... 39 Postal Service 1 2010-07-01 2010-07-01 false Minutes of meetings. 6.5 Section 6.5 Postal... 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. 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.

  4. Reaction time in Parkinson's disease.

    PubMed

    Evarts, E V; Teräväinen, H; Calne, D B

    1981-03-01

    Both reaction time and movement time tend to be prolonged in Parkinson's disease, but they are often impaired independently of each other. Prolongation of RT is relatively slight, while MT undergoes more substantial and consistent disturbance. Choice RT and kinaesthetic RT do not have any advantage over simple visual RT as measurements of neurological deficit in parkinsonism, since they are all impaired to the same extent. MT is more useful than RT as an objective indicator of therapeutic efficacy, but further studies of RT (with tests requiring programming of displacement, velocity, and accuracy) may provide insights into the nature of the central motor disorder in Parkinson's disease.

  5. The STAFF studies of the first 5 minutes of percutaneous coronary angioplasty balloon occlusion in man.

    PubMed

    Warren, Stafford G; Wagner, Galen S

    2014-01-01

    The Staff Studies comprise a database of 228 patients undergoing elective 5 minute coronary artery balloon occlusion angioplasty at a single center in the pre-stent era in whom standard and high-frequency electrocardiographic and nuclear information was obtained immediately before, during and after balloon occlusion. The data were then analyzed by multiple investigators at different international academic centers from different perspectives. Simulating in a clinical setting the first 5 minutes of a heart attack, this database, now in digital format, is the largest database to date documenting standard and high-frequency ECG changes from the onset and for 5 minutes during acute coronary artery occlusion, with resting and occlusion imaging in a subset of these patients. The history, methodology, and legacy of these studies are discussed in this paper.

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

    NASA Technical Reports Server (NTRS)

    Isaacson, Dennis L.; Ripple, William J.

    1990-01-01

    Two digital elevation models are compared 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.

  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. 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.

  10. 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.

  11. The 5-minute Apgar score: survival and short-term outcomes in extremely low-birth-weight infants.

    PubMed

    Phalen, Ann Gibbons; Kirkby, Sharon; Dysart, Kevin

    2012-01-01

    The Apgar score is a standardized tool for evaluating newborns in the delivery room. Despite its long history and widespread use, debate remains over its reliability of predicting neonatal outcomes, especially in extremely low-birth-weight premature infants. The aim of the study was to examine the relationship between the 5-minute Apgar score of extremely low-birth-weight infants, as it relates to survival and morbidities associated with prematurity and length of hospital stay. A retrospective query of the Alere neonatal database from 2001 to 2011 examined all infants less than 32 weeks' gestation and less than 1000-g birth weight. The 5-minute Apgar score was divided into 2 groups, score of 4 or greater or less than 4. The study compared results of the 5-minute Apgar score and associated morbidities in surviving infants. Statistical analyses included chi-square, Fisher exact test, t test, and multivariate regression. The sample consisted of 3898 infants with an 86.4% (n = 3366) survival rate. Controlling for gestational age and birth weight, surviving infants with a 5-minute Apgar score of less than 4 were more likely to demonstrate nonintact survival. Infants with a low 5-minute Apgar score have greater risk for mortality and morbidities associated with prematurity.

  12. 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.

  13. Autonomous Vehicles: Disengagements, Accidents and Reaction Times

    PubMed Central

    Dixit, Vinayak V.; Chand, Sai; Nair, Divya J.

    2016-01-01

    Autonomous vehicles are being viewed with scepticism in their ability to improve safety and the driving experience. A critical issue with automated driving at this stage of its development is that it is not yet reliable and safe. When automated driving fails, or is limited, the autonomous mode disengages and the drivers are expected to resume manual driving. For this transition to occur safely, it is imperative that drivers react in an appropriate and timely manner. Recent data released from the California trials provide compelling insights into the current factors influencing disengagements of autonomous mode. Here we show that the number of accidents observed has a significantly high correlation with the autonomous miles travelled. The reaction times to take control of the vehicle in the event of a disengagement was found to have a stable distribution across different companies at 0.83 seconds on average. However, there were differences observed in reaction times based on the type of disengagements, type of roadway and autonomous miles travelled. Lack of trust caused by the exposure to automated disengagements was found to increase the likelihood to take control of the vehicle manually. Further, with increased vehicle miles travelled the reaction times were found to increase, which suggests an increased level of trust with more vehicle miles travelled. We believe that this research would provide insurers, planners, traffic management officials and engineers fundamental insights into trust and reaction times that would help them design and engineer their systems. PMID:27997566

  14. Autonomous Vehicles: Disengagements, Accidents and Reaction Times.

    PubMed

    Dixit, Vinayak V; Chand, Sai; Nair, Divya J

    2016-01-01

    Autonomous vehicles are being viewed with scepticism in their ability to improve safety and the driving experience. A critical issue with automated driving at this stage of its development is that it is not yet reliable and safe. When automated driving fails, or is limited, the autonomous mode disengages and the drivers are expected to resume manual driving. For this transition to occur safely, it is imperative that drivers react in an appropriate and timely manner. Recent data released from the California trials provide compelling insights into the current factors influencing disengagements of autonomous mode. Here we show that the number of accidents observed has a significantly high correlation with the autonomous miles travelled. The reaction times to take control of the vehicle in the event of a disengagement was found to have a stable distribution across different companies at 0.83 seconds on average. However, there were differences observed in reaction times based on the type of disengagements, type of roadway and autonomous miles travelled. Lack of trust caused by the exposure to automated disengagements was found to increase the likelihood to take control of the vehicle manually. Further, with increased vehicle miles travelled the reaction times were found to increase, which suggests an increased level of trust with more vehicle miles travelled. We believe that this research would provide insurers, planners, traffic management officials and engineers fundamental insights into trust and reaction times that would help them design and engineer their systems.

  15. 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…

  16. 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).

  17. 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).

  18. Deciphering Time Scale Hierarchy in Reaction Networks.

    PubMed

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

    2016-03-03

    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.

  19. Time-delayed reaction-diffusion fronts

    NASA Astrophysics Data System (ADS)

    Isern, Neus; Fort, Joaquim

    2009-11-01

    A time-delayed second-order approximation for the front speed in reaction-dispersion systems was obtained by Fort and Méndez [Phys. Rev. Lett. 82, 867 (1999)]. Here we show that taking proper care of the effect of the time delay on the reactive process yields a different evolution equation and, therefore, an alternate equation for the front speed. We apply the new equation to the Neolithic transition. For this application the new equation yields speeds about 10% slower than the previous one.

  20. 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.

  1. 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.

  2. 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…

  3. NMDA receptor subunits in the adult rat hippocampus undergo similar changes after 5 minutes in an open field and after LTP induction.

    PubMed

    Baez, Maria Veronica; Oberholzer, Maria Victoria; Cercato, Magali Cecilia; Snitcofsky, Marina; Aguirre, Alejandra Ines; Jerusalinsky, Diana Alicia

    2013-01-01

    NMDA receptor subunits change during development and their synaptic expression is modified rapidly after synaptic plasticity induction in hippocampal slices. However, there is scarce information on subunits expression after synaptic plasticity induction or memory acquisition, particularly in adults. GluN1, GluN2A and GluN2B NMDA receptor subunits were assessed by western blot in 1) adult rats that had explored an open field (OF) for 5 minutes, a time sufficient to induce habituation, 2) mature rat hippocampal neuron cultures depolarized by KCl and 3) hippocampal slices from adult rats where long term potentiation (LTP) was induced by theta-burst stimulation (TBS). GluN1 and GluN2A, though not GluN2B, were significantly higher 70 minutes--but not 30 minutes--after a 5 minutes session in an OF. GluN1 and GluN2A total immunofluorescence and puncta in neurites increased in cultures, as evaluated 70 minutes after KCl stimulation. Similar changes were found in hippocampal slices 70 minutes after LTP induction. To start to explore underlying mechanisms, hippocampal slices were treated either with cycloheximide (a translation inhibitor) or actinomycin D (a transcription inhibitor) during electrophysiological assays. It was corroborated that translation was necessary for LTP induction and expression. The rise in GluN1 depends on transcription and translation, while the increase in GluN2A appears to mainly depend on translation, though a contribution of some remaining transcriptional activity during actinomycin D treatment could not be rouled out. LTP effective induction was required for the subunits to increase. Although in the three models same subunits suffered modifications in the same direction, within an apparently similar temporal course, further investigation is required to reveal if they are related processes and to find out whether they are causally related with synaptic plasticity, learning and memory.

  4. 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…

  5. 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…

  6. 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.

  7. 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.

  8. 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.

  9. 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

  10. 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.

  11. 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.

  12. 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.)

  13. Time reversal tests in polarized neutron reactions

    SciTech Connect

    Asahi, Koichiro; Bowman, J.D.; Crawford, B.

    1998-11-01

    This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). In recent years the nuclear weak interaction has been studied in the compound nucleus via parity violation. The observed parity-violating effects are strongly enhanced by nuclear structure. The predictions are that the interaction of polarized neutrons with polarized nuclear targets could be also used to perform sensitive tests of time-reversal-violation because of the nuclear enhancements. The author has designed experiments to search for time-reversal violation in neutron-nucleus interactions. He has also developed techniques to polarize neutrons with laser-polarized {sup 3}He gas targets. Using the polarized {sup 3}He neutron spin filter, he has performed two experiments at LANSCE: an absolute neutron beam polarization measurement with an accuracy of 0.2--0.3% and a neutron spin-rotation measurement on a {sup 139}La sample.

  14. Mean recombination time of diffusion controlled geminate reactions

    SciTech Connect

    Mozumder, A.

    1982-05-15

    A recently introduced method by Deutch for determining the mean passage time for diffusion controlled processes (J. Chem. Phys. 73, 4700 (1980)) has been further developed for application to the reactions of geminate pairs. First, a nonzero probability of escaping geminate recombination requires a normalized definition of mean recombination time which is done consistently. Second, only a finite dose results in a finite mean reaction time. Adopting a special outer boundary condition related to the dose, mean recombination times are calculated for ionic and neutral geminate reactions. For application in radiation- and photochemistry, fully and partially diffusion controlled conditions are applied to ionic and neutral cases, respectively.

  15. 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…

  16. 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

  17. 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

  18. Linking impulse response functions to reaction time: Rod and cone reaction time data and a computational model

    PubMed Central

    Cao, Dingcai; Zele, Andrew J.; Pokorny, Joel

    2007-01-01

    Reaction times for incremental and decremental stimuli were measured at five suprathreshold contrasts for six retinal illuminance levels where rods alone (0.002–0.2 Trolands), rods and cones (2–20 Trolands) or cones alone (200 Trolands) mediated detection. A 4-primary photostimulator allowed independent control of rod or cone excitations. This is the first report of reaction times to isolated rod or cone stimuli at mesopic light levels under the same adaptation conditions. The main findings are: 1) For rods, responses to decrements were faster than increments, but cone reaction times were closely similar. 2) At light levels where both systems were functional, rod reaction times were ~20 ms longer. The data were fitted with a computational model that incorporates rod and cone impulse response functions and a stimulus-dependent neural sensory component that triggers a motor response. Rod and cone impulse response functions were derived from published psychophysical two-pulse threshold data and temporal modulation transfer functions. The model fits were accomplished with a limited number of free parameters: two global parameters to estimate the irreducible minimum reaction time for each receptor type, and one local parameter for each reaction time versus contrast function. This is the first model to provide a neural basis for the variation in reaction time with retinal illuminance, stimulus contrast, stimulus polarity, and receptor class modulated. PMID:17346763

  19. Comparison of Sprint Reaction and Visual Reaction Times of Athletes in Different Branches

    ERIC Educational Resources Information Center

    Akyüz, Murat; Uzaldi, Basar Basri; Akyüz, Öznur; Dogru, Yeliz

    2017-01-01

    The aims of this study are to analyse sprint reaction and visual reaction times of female athletes of different branches competing in Professional leagues and to show the differences between them. 42 voluntary female athletes from various branches of Professional leagues of Istanbul (volleyball, basketball, handball) were included in the…

  20. 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

  1. Control of response timing occurs during the simple reaction time interval but on-line for choice reaction time.

    PubMed

    Maslovat, Dana; Klapp, Stuart T; Jagacinski, Richard J; Franks, Ian M

    2014-10-01

    The preparation of multiple element movements has been examined for decades, with no clear explanation offered for the disparate results observed. Results from 2 experiments are presented and, in conjunction with previous results, a theoretical interpretation is offered regarding the preparatory processes that occur before, during and after the reaction time (RT) interval for multiple element movements during both simple and choice RT paradigms. In Experiment 1, number of elements and timing complexity were manipulated in a simple RT key-press task, using a startling acoustic stimulus to probe advance preparation. Both startle and nonstartle RT increased with number of movement elements and for a movement with increased timing complexity, providing evidence that the control of response timing occurs during the RT interval. In Experiment 2, the production of key-press movements of varying number of elements was compared in a simple versus choice RT paradigm. Results indicated that simple RT was affected by the number of elements, yet choice RT was not. Additionally, choice RT trials showed significantly longer interresponse intervals compared with those observed in simple RT trials, providing evidence for online processing in choice RT. The results of both studies, together with previous findings, suggest that planning of the timing of the onsets of the elements is prepared during simple RT, whereas planning of other aspects of the sequence of elements seems to occur in the foreperiod prior to the "go" signal. Conversely, in the choice RT paradigm, timing seems to be controlled online. This explanation may bring closure on difficulties encountered in over 50 years of research examining response preparation for complex movements.

  2. 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.

  3. Overlap of movement planning and movement execution reduces reaction time.

    PubMed

    Orban de Xivry, Jean-Jacques; Legrain, Valéry; Lefèvre, Philippe

    2017-01-01

    Motor planning is the process of preparing the appropriate motor commands in order to achieve a goal. This process has largely been thought to occur before movement onset and traditionally has been associated with reaction time. However, in a virtual line bisection task we observed an overlap between movement planning and execution. In this task performed with a robotic manipulandum, we observed that participants (n = 30) made straight movements when the line was in front of them (near target) but often made curved movements when the same target was moved sideways (far target, which had the same orientation) in such a way that they crossed the line perpendicular to its orientation. Unexpectedly, movements to the far targets had shorter reaction times than movements to the near targets (mean difference: 32 ms, SE: 5 ms, max: 104 ms). In addition, the curvature of the movement modulated reaction time. A larger increase in movement curvature from the near to the far target was associated with a larger reduction in reaction time. These highly curved movements started with a transport phase during which accuracy demands were not taken into account. We conclude that an accuracy demand imposes a reaction time penalty if processed before movement onset. This penalty is reduced if the start of the movement consists of a transport phase and if the movement plan can be refined with respect to accuracy demands later in the movement, hence demonstrating an overlap between movement planning and execution.

  4. 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.

  5. Simple Reaction Time and Statistical Facilitation: A Parallel Grains Model

    ERIC Educational Resources Information Center

    Miller, Jeff; Ulrich, Rolf

    2003-01-01

    A race-like model is developed to account for various phenomena arising in simple reaction time (RT) tasks. Within the model, each stimulus is represented by a number of grains of information or activation processed in parallel. The stimulus is detected when a criterion number of activated grains reaches a decision center. Using the concept of…

  6. The PrimeTime Expose: Reactions and Recommendations.

    ERIC Educational Resources Information Center

    Child Care Information Exchange, 1991

    1991-01-01

    Describes "Day Care Nightmares," a two-part expose on ABC's PrimeTime Live, broadcast in June 1991, in which negative claims were made about the state of day care in the United States. A variety of advocates, policymakers, and child care providers present their reactions to the shows and their recommendations on what action can be taken.…

  7. 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…

  8. Examining the role of finite reaction times in swarming models

    NASA Astrophysics Data System (ADS)

    Copenhagen, Katherine; Quint, David; Gopinathan, Ajay

    2015-03-01

    Modeling collective behavior in biological and artificial systems has had much success in recent years at predicting and mimicing real systems by utilizing techniques borrowed from modelling many particle systems interacting with physical forces. However unlike inert particles interacting with instantaneous forces, living organisms have finite reaction times, and behaviors that vary from individual to individual. What constraints do these physiological effects place on the interactions between individuals in order to sustain a robust ordered state? We use a self-propelled agent based model in continuous space based on previous models by Vicsek and Couzin including alignment and separation maintaining interactions to examine the behavior of a single cohesive group of organisms. We found that for very short reaction times the system is able to form an ordered state even in the presence of heterogeneities. However for larger more physiological reaction times organisms need a buffer zone with no cohesive interactions in order to maintain an ordered state. Finally swarms with finite reaction times and behavioral heterogeneities are able to dynamically sort out individuals with impaired function and sustain order.

  9. 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…

  10. 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…

  11. The Time Course of Corticospinal Excitability during a Simple Reaction Time Task

    PubMed Central

    Kennefick, Michael; Maslovat, Dana; Carlsen, Anthony N.

    2014-01-01

    The production of movement in a simple reaction time task can be separated into two time periods: the foreperiod, which is thought to include preparatory processes, and the reaction time interval, which includes initiation processes. To better understand these processes, transcranial magnetic stimulation has been used to probe corticospinal excitability at various time points during response preparation and initiation. Previous research has shown that excitability decreases prior to the “go” stimulus and increases following the “go”; however these two time frames have been examined independently. The purpose of this study was to measure changes in CE during both the foreperiod and reaction time interval in a single experiment, relative to a resting baseline level. Participants performed a button press movement in a simple reaction time task and excitability was measured during rest, the foreperiod, and the reaction time interval. Results indicated that during the foreperiod, excitability levels quickly increased from baseline with the presentation of the warning signal, followed by a period of stable excitability leading up to the “go” signal, and finally a rapid increase in excitability during the reaction time interval. This excitability time course is consistent with neural activation models that describe movement preparation and response initiation. PMID:25406079

  12. Reaction times to neon, LED, and fast incandescent brake lamps.

    PubMed

    Sivak, M; Flannagan, M J; Sato, T; Traube, E C; Aoki, M

    1994-06-01

    Standard incandescent brake lamps have a relatively slow rise time. It takes approximately a quarter of a second for them to reach 90% of asymptotic light output, causing potential delays in responses by following drivers. The present study evaluated reaction times to brake signals from standard incandescent brake lamps and from three alternative brake lamps with substantially faster rise times: neon, LED, and fast incandescent. The study, performed in a laboratory, simulated a daytime driving condition. The subject's task was to respond as quickly as possible to the onset of either of two brake lamps in the visual periphery, while engaged in a central tracking task. Brake signals were presented at two levels of luminous intensity. The results showed that reaction times to the alternative brake lamps were faster than to the standard incandescent lamp, with the advantage averaging 166 ms for the LED and neon lamps, and 135 ms for the fast incandescent lamp. A reduction of the signals' luminous intensity from 42 cd to 5 cd increased the reaction time by 84 ms.

  13. Aging 5 years in 5 minutes: the effect of taking a memory test on older adults' subjective age.

    PubMed

    Hughes, Matthew L; Geraci, Lisa; De Forrest, Ross L

    2013-12-01

    How old one feels-one's subjective age-has been shown to predict important psychological and health outcomes. The current studies examined the effect of taking a standard memory test on older adults' subjective age. Study 1 showed that older adults felt older after taking a standard neuropsychological screening test and participating in a free-recall experiment than they felt at baseline. Study 2 showed that the effect was selective to older adults: Younger adults' subjective age was not affected by participating in the memory experiment. Study 3 showed that the subjective-aging effect was specific to memory, as taking a vocabulary test for a similar amount of time did not affect older adults' subjective age. Finally, Study 4 showed that simply expecting to take a memory test subjectively aged older adults. The results indicate that being in a memory-testing context affects older adults' self-perception by making them feel older.

  14. A simple and efficient method for poly-3-hydroxybutyrate quantification in diazotrophic bacteria within 5 minutes using flow cytometry.

    PubMed

    Alves, L P S; Almeida, A T; Cruz, L M; Pedrosa, F O; de Souza, E M; Chubatsu, L S; Müller-Santos, M; Valdameri, G

    2017-01-16

    The conventional method for quantification of polyhydroxyalkanoates based on whole-cell methanolysis and gas chromatography (GC) is laborious and time-consuming. In this work, a method based on flow cytometry of Nile red stained bacterial cells was established to quantify poly-3-hydroxybutyrate (PHB) production by the diazotrophic and plant-associated bacteria, Herbaspirillum seropedicae and Azospirillum brasilense. The method consists of three steps: i) cell permeabilization, ii) Nile red staining, and iii) analysis by flow cytometry. The method was optimized step-by-step and can be carried out in less than 5 min. The final results indicated a high correlation coefficient (R2=0.99) compared to a standard method based on methanolysis and GC. This method was successfully applied to the quantification of PHB in epiphytic bacteria isolated from rice roots.

  15. A simple and efficient method for poly-3-hydroxybutyrate quantification in diazotrophic bacteria within 5 minutes using flow cytometry

    PubMed Central

    Alves, L.P.S.; Almeida, A.T.; Cruz, L.M.; Pedrosa, F.O.; de Souza, E.M.; Chubatsu, L.S.; Müller-Santos, M.; Valdameri, G.

    2017-01-01

    The conventional method for quantification of polyhydroxyalkanoates based on whole-cell methanolysis and gas chromatography (GC) is laborious and time-consuming. In this work, a method based on flow cytometry of Nile red stained bacterial cells was established to quantify poly-3-hydroxybutyrate (PHB) production by the diazotrophic and plant-associated bacteria, Herbaspirillum seropedicae and Azospirillum brasilense. The method consists of three steps: i) cell permeabilization, ii) Nile red staining, and iii) analysis by flow cytometry. The method was optimized step-by-step and can be carried out in less than 5 min. The final results indicated a high correlation coefficient (R2=0.99) compared to a standard method based on methanolysis and GC. This method was successfully applied to the quantification of PHB in epiphytic bacteria isolated from rice roots. PMID:28099582

  16. The effect of ego depletion on sprint start reaction time.

    PubMed

    Englert, Chris; Bertrams, Alex

    2014-10-01

    In the current study, we consider that optimal sprint start performance requires the self-control of responses. Therefore, start performance should depend on athletes' self-control strength. We assumed that momentary depletion of self-control strength (ego depletion) would either speed up or slow down the initiation of a sprint start, where an initiation that was sped up would carry the increased risk of a false start. Applying a mixed between- (depletion vs. nondepletion) and within- (before vs. after manipulation of depletion) subjects design, we tested the start reaction times of 37 sport students. We found that participants' start reaction times decelerated after finishing a depleting task, whereas it remained constant in the nondepletion condition. These results indicate that sprint start performance can be impaired by unrelated preceding actions that lower momentary self-control strength. We discuss practical implications in terms of optimizing sprint starts and related overall sprint performance.

  17. Interaction time evaluation in dissipative heavy ion reactions

    SciTech Connect

    De Rosa, A.; Inglima, G.; Romano, M.; Russo, V.; Sandoli, M.; Cardella, G.; Pappalardo, G.; Rizzo, F.; Fortuna, G.; Stefanini, A.M.

    1988-03-01

    Excitation functions have been measured for different charge products of the /sup 28/Si+/sup 48/Ti reaction in the laboratory energy range 120--127 MeV in 250-keV steps at theta/sub lab/ = 28/sup 0/, 32/sup 0/, and 40/sup 0/. Coherence energies of dissipative cross sections have been evaluated by statistical fluctuation analysis. The role of the angular dependence of the coherence energy in determining the interaction time is discussed

  18. 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

  19. 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.

  20. PCR (Polymerase Chain Reaction) Testing for Leishmaniasis

    DTIC Science & Technology

    1993-10-20

    reactions. Prior to temperature cycling, this moderately heat stable enzyme selectively excises uracil residues which have been incorporated into DNA... temperature . Despite these precautions, some non-specific annealing of PCR primers does occur, even with single copy gene detection, and more so with...Mallinckrodt) in slightly hypotonic saline and allowed to remain at ambient temperature for 5 minutes, during which time RBC’s are lysed. Centrifugation

  1. Assay of gliadin by real-time immunopolymerase chain reaction.

    PubMed

    Henterich, Nadine; Osman, Awad A; Méndez, Enrique; Mothes, Thomas

    2003-10-01

    Patients with coeliac disease (gluten-sensitive enteropathy) are intolerant against gliadins from wheat and the respective proteins from related cereals and have to keep a lifelong gluten-free diet. For control of gliadin in gluten-free food sensitive assay techniques are necessary. We developed an immunopolymerase chain reaction (iPCR) assay for gliadin. In this technique immunological detection of gliadin by a monoclonal antibody R5 conjugated with an oligonucleotide is amplified by PCR. For quantification, iPCR was performed as real-time PCR (real-time iPCR) in one step. By means of real-time iPCR, the sensitivity of gliadin analysis was increased more than 30-fold above the level reached by enzyme immunoassay. Real time-iPCR using R5 directly conjugated with oligonucleotide was clearly more sensitive than real time-iPCR applying sequentially biotinylated R5, streptavidin, and biotinylated oligonucleotide. With directly conjugated R5 gliadin was detected at a concentration as low as 0.16 ng/mL corresponding to 16 microg gliadin/100 g food or 0.16 ppm (corresponding to 0.25 g of food extracted in 10 mL of solvent and 25-fold dilution of the extract prior to analysis). This is the first report applying the highly sensitive technique of iPCR for gliadin analysis. Furthermore, this is the first approach to perform real-time iPCR in one step without changing the reaction vessels after enzyme immunoassay for subsequent PCR analysis thus minimizing risks of contamination and loss of sensitivity.

  2. Critical time scales for advection-diffusion-reaction processes

    NASA Astrophysics Data System (ADS)

    Ellery, Adam J.; Simpson, Matthew J.; McCue, Scott W.; Baker, Ruth E.

    2012-04-01

    The concept of local accumulation time (LAT) was introduced by Berezhkovskii and co-workers to give a finite measure of the time required for the transient solution of a reaction-diffusion equation to approach the steady-state solution [A. M. Berezhkovskii, C. Sample, and S. Y. Shvartsman, Biophys. J.BIOJAU0006-349510.1016/j.bpj.2010.07.045 99, L59 (2010); A. M. Berezhkovskii, C. Sample, and S. Y. Shvartsman, Phys. Rev. EPLEEE81539-375510.1103/PhysRevE.83.051906 83, 051906 (2011)]. Such a measure is referred to as a critical time. Here, we show that LAT is, in fact, identical to the concept of mean action time (MAT) that was first introduced by McNabb [A. McNabb and G. C. Wake, IMA J. Appl. Math.IJAMDM0272-496010.1093/imamat/47.2.193 47, 193 (1991)]. Although McNabb's initial argument was motivated by considering the mean particle lifetime (MPLT) for a linear death process, he applied the ideas to study diffusion. We extend the work of these authors by deriving expressions for the MAT for a general one-dimensional linear advection-diffusion-reaction problem. Using a combination of continuum and discrete approaches, we show that MAT and MPLT are equivalent for certain uniform-to-uniform transitions; these results provide a practical interpretation for MAT by directly linking the stochastic microscopic processes to a meaningful macroscopic time scale. We find that for more general transitions, the equivalence between MAT and MPLT does not hold. Unlike other critical time definitions, we show that it is possible to evaluate the MAT without solving the underlying partial differential equation (pde). This makes MAT a simple and attractive quantity for practical situations. Finally, our work explores the accuracy of certain approximations derived using MAT, showing that useful approximations for nonlinear kinetic processes can be obtained, again without treating the governing pde directly.

  3. 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

  4. 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

  5. Effects of occurrence and time uncertainties on reaction and movement times of children.

    PubMed

    Ozmun, J C; Surburg, P R; Cleland, F E

    1989-06-01

    This study investigated the influence of catch trial (CT) occurrence and foreperiod variation on reaction time and movement time of children of different ages. 48 children were randomly assigned to a CT group or a no-CT group. All received randomly ordered foreperiods. The presence of CTs and varying foreperiods played an inhibitory role in the motor performance of children.

  6. Transcriptional dynamics with time-dependent reaction rates

    NASA Astrophysics Data System (ADS)

    Nandi, Shubhendu; Ghosh, Anandamohan

    2015-02-01

    Transcription is the first step in the process of gene regulation that controls cell response to varying environmental conditions. Transcription is a stochastic process, involving synthesis and degradation of mRNAs, that can be modeled as a birth-death process. We consider a generic stochastic model, where the fluctuating environment is encoded in the time-dependent reaction rates. We obtain an exact analytical expression for the mRNA probability distribution and are able to analyze the response for arbitrary time-dependent protocols. Our analytical results and stochastic simulations confirm that the transcriptional machinery primarily act as a low-pass filter. We also show that depending on the system parameters, the mRNA levels in a cell population can show synchronous/asynchronous fluctuations and can deviate from Poisson statistics.

  7. Serious adverse neonatal outcomes such as 5-minute Apgar score of zero and seizures or severe neurologic dysfunction are increased in planned home births after cesarean delivery.

    PubMed

    Grünebaum, Amos; McCullough, Laurence B; Arabin, Birgit; Chervenak, Frank A

    2017-01-01

    The United States is with 37,451 home births in 2014 the country with the largest absolute number of home births among all developed countries. The purpose of this study was to examine the occurrence and risks of a 5-minute Apgar score of zero and neonatal seizures or serious neurologic dysfunction in women with a history of prior cesarean delivery for planned home vaginal birth after cesarean (VBAC), compared to hospital VBAC and hospital birth cesarean deliveries for term normal weight infants in the United States from 2007-2014. We report in this study outcomes of women who had one or more prior cesarean deliveries and included women who had a successful vaginal birth after a trial of labor after cesarean (TOLAC) at home and in the hospital, and a repeat cesarean delivery in the hospital. We excluded preterm births (<37 weeks) and infants weighing under 2500 g. Hospital VBACS were the reference. Women with a planned home birth VBAC had an approximately 10-fold and higher increase in adverse neonatal outcomes when compared to hospital VBACS and hospital repeat cesarean deliveries, a significantly higher incidence and risk of a 5-minute Apgar score of 0 of 1 in 890 (11.24/10,000, relative risk 9.04, 95% confidence interval 4-20.39, p<.0001) and an incidence of neonatal seizures or severe neurologic dysfunction of 1 in 814 (Incidence: 12.27/10,000, relative risk 11.19, 95% confidence interval 5.13-24.29, p<.0001). Because of the significantly increased neonatal risks, obstetric providers should therefore not offer or perform planned home TOLACs and for those desiring a VBAC should strongly recommend a planned TOLAC in the appropriate hospital setting. We emphasize that this stance should be accompanied by effective efforts to make TOLAC available in the appropriate hospital setting.

  8. Serious adverse neonatal outcomes such as 5-minute Apgar score of zero and seizures or severe neurologic dysfunction are increased in planned home births after cesarean delivery

    PubMed Central

    McCullough, Laurence B.; Arabin, Birgit; Chervenak, Frank A.

    2017-01-01

    The United States is with 37,451 home births in 2014 the country with the largest absolute number of home births among all developed countries. The purpose of this study was to examine the occurrence and risks of a 5-minute Apgar score of zero and neonatal seizures or serious neurologic dysfunction in women with a history of prior cesarean delivery for planned home vaginal birth after cesarean (VBAC), compared to hospital VBAC and hospital birth cesarean deliveries for term normal weight infants in the United States from 2007–2014. We report in this study outcomes of women who had one or more prior cesarean deliveries and included women who had a successful vaginal birth after a trial of labor after cesarean (TOLAC) at home and in the hospital, and a repeat cesarean delivery in the hospital. We excluded preterm births (<37 weeks) and infants weighing under 2500 g. Hospital VBACS were the reference. Women with a planned home birth VBAC had an approximately 10-fold and higher increase in adverse neonatal outcomes when compared to hospital VBACS and hospital repeat cesarean deliveries, a significantly higher incidence and risk of a 5-minute Apgar score of 0 of 1 in 890 (11.24/10,000, relative risk 9.04, 95% confidence interval 4–20.39, p<.0001) and an incidence of neonatal seizures or severe neurologic dysfunction of 1 in 814 (Incidence: 12.27/10,000, relative risk 11.19, 95% confidence interval 5.13–24.29, p<.0001). Because of the significantly increased neonatal risks, obstetric providers should therefore not offer or perform planned home TOLACs and for those desiring a VBAC should strongly recommend a planned TOLAC in the appropriate hospital setting. We emphasize that this stance should be accompanied by effective efforts to make TOLAC available in the appropriate hospital setting. PMID:28319128

  9. Locus of the intensity effect in simple reaction time tasks.

    PubMed

    Jaśkowski, Piotr; Kurczewska, Marta; Nowik, Agnieszka; van der Lubbe, Rob H J; Verleger, Rolf

    2007-11-01

    Evidence is still inconclusive regarding the locus of the stimulus intensity effect on information processing in reaction tasks. Miller, Ulrich, and Rinkenauer (1999) addressed this question by assessing the intensity effect on stimulus- and response-locked lateralized readiness potentials (LRPs) as indices of the sensory and motor parts of reaction time (RT). In the case of visual stimuli, they observed that application of brighter stimuli resulted in a shortening of RT and stimulus-locked LRP (S-LRP), but not of response-locked LRP (R-LRP). The results for auditory stimuli, however, were unclear. In spite of a clear RT reduction due to increased loudness, neither S-LRP nor R-LRP onset was affected. A reason for this failure might have been a relatively small range of intensity variation and the type of task. To check for this possibility, we performed three experiments in which broader ranges of stimulus intensities and simple, rather than choice, response tasks were used. Although the intensity effect on the R-LRP was negligible, S-LRP followed RT changes, irrespective of stimulus modality. These findings support the conclusion that stimulus intensity exerts its effect before the start of motoric processes. Finally, S-LRP and R-LRP findings are discussed within a broader information-processing perspective to check the validity of the claim that S-LRP and R-LRP can, indeed, be considered as pure estimates of the duration of sensory and motor processes.

  10. Acute effects of static and dynamic stretching on balance, agility, reaction time and movement time.

    PubMed

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

    2014-05-01

    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 pointsStatic 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.

  11. 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

  12. Subcortical motor circuit excitability during simple and choice reaction time.

    PubMed

    Maslovat, Dana; Carlsen, Anthony N; Franks, Ian M

    2012-06-01

    The purpose of the current study was to examine the relationship between movement preparation and excitability of subcortical motor circuits, as measured by the reflexive response to a startling acoustic stimulus. We compared the size and incidence of activation in the sternocleidomastoid (startle indicator) from participants completing either a simple or choice reaction time (RT) task. Consistent with predictions, results indicated that the startle reflex habituated after several presentations of the SAS for the choice RT group but not for the simple RT group, which we attributed to advance motor preparatory processes involved in a simple RT task. Additionally, when participants from the choice RT group were put into a simple RT condition, the startle reflex response returned to nonhabituated levels. We conclude that the increased corticospinal activation associated with advance preparation may also result in increased subcortical activation, accounting for the observed lack of habituation to a startling stimulus in simple RT.

  13. The Simplest Chronoscope V: A Theory of Dual Primary and Secondary Reaction Time Systems.

    PubMed

    Montare, Alberto

    2016-12-01

    Extending work by Montare, visual simple reaction time, choice reaction time, discriminative reaction time, and overall reaction time scores obtained from college students by the simplest chronoscope (a falling meterstick) method were significantly faster as well as significantly less variable than scores of the same individuals from electromechanical reaction timers (machine method). Results supported the existence of dual reaction time systems: an ancient primary reaction time system theoretically activating the V5 parietal area of the dorsal visual stream that evolved to process significantly faster sensory-motor reactions to sudden stimulations arising from environmental objects in motion, and a secondary reaction time system theoretically activating the V4 temporal area of the ventral visual stream that subsequently evolved to process significantly slower sensory-perceptual-motor reactions to sudden stimulations arising from motionless colored objects.

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

    PubMed

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

    2016-09-05

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

  15. 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

  16. 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.

  17. Decreasing auditory Simon effects across reaction time distributions.

    PubMed

    Xiong, Aiping; Proctor, Robert W

    2016-01-01

    The Simon effect for left-right visual stimuli previously has been shown to decrease across the reaction time (RT) distribution. This decrease has been attributed to automatic activation of the corresponding response, which then dissipates over time. In contrast, for left-right tone stimuli, the Simon effect has not been found to decrease across the RT distribution but instead tends to increase. It has been proposed that automatic activation occurs through visuomotor information transmission, whereas the auditory Simon effect reflects cognitive coding interference and not automatic activation. In 4 experiments, we examined distributions of the auditory Simon effect for RT, percentage error (PE), and an inverse efficiency score [IES = RT/(1 - PE)] as a function of tone frequency and duration to determine whether the activation-dissipation account is also applicable to auditory stimuli. Consistent decreasing functions were found for the RT Simon effect distribution with short-duration tones of low frequency and for the PE and IES Simon effect distributions for all durations and frequency sets. Together, these findings provide robust evidence that left and right auditory stimuli also produce decreasing Simon effect distribution functions suggestive of automatic activation and dissipation of the corresponding response.

  18. Radiologic correlates of reaction time measurements in olivopontocerebellar atrophy.

    PubMed

    Botez, M I; Pedraza, O L; Botez-Marquard, T; Vézina, J L; Elie, R

    1993-01-01

    We measured simple visual and auditory reaction time (RT) and movement time (MT) in 32 patients with olivopontocerebellar atrophy (OPCA) in comparison to 32 control subjects. In addition, we followed 2 approaches to radiologic assessment by computed tomographic scans: subjective (by inspection of films) and objective (by measurement of 4 radiologic ratios at the level of the posterior fossa and 1 ratio at the supratentorial level). All OPCA patients had various degrees of cerebellar atrophy and lengthened RT and MT in comparison to their controls. There were no significant differences in RT and MT performances in patients with mild-moderate versus those with severe cerebellar atrophy as assessed by inspection of their films. OPCA patients with severe versus mild-moderate atrophy evaluated by 3 measures, i.e., brainstem, brachium pontis and fourth ventricle ratios, presented few significantly lengthened RT and MT performances. In contrast, patients with severe atrophy revealed by the midbrain ratio had significantly lengthened RT and MT performances compared to those with mild-moderate atrophy assessed by this ratio on 7 of 8 measures; the 8th measure showed a borderline significant difference. This could be explained by the fact that atrophy at the midbrain level is the only one which involves dopaminergic, noradrenergic and glutamatergic structures and pathways.

  19. 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.

  20. 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.

  1. Bayesian parametric estimation of stop-signal reaction time distributions.

    PubMed

    Matzke, Dora; Dolan, Conor V; Logan, Gordon D; Brown, Scott D; Wagenmakers, Eric-Jan

    2013-11-01

    The cognitive concept of response inhibition can be measured with the stop-signal paradigm. In this paradigm, participants perform a 2-choice response time (RT) task where, on some of the trials, the primary task is interrupted by a stop signal that prompts participants to withhold their response. The dependent variable of interest is the latency of the unobservable stop response (stop-signal reaction time, or SSRT). Based on the horse race model (Logan & Cowan, 1984), several methods have been developed to estimate SSRTs. None of these approaches allow for the accurate estimation of the entire distribution of SSRTs. Here we introduce a Bayesian parametric approach that addresses this limitation. Our method is based on the assumptions of the horse race model and rests on the concept of censored distributions. We treat response inhibition as a censoring mechanism, where the distribution of RTs on the primary task (go RTs) is censored by the distribution of SSRTs. The method assumes that go RTs and SSRTs are ex-Gaussian distributed and uses Markov chain Monte Carlo sampling to obtain posterior distributions for the model parameters. The method can be applied to individual as well as hierarchical data structures. We present the results of a number of parameter recovery and robustness studies and apply our approach to published data from a stop-signal experiment.

  2. Manual choice reaction times in the rate-domain.

    PubMed

    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.

  3. Online psychophysics: reaction time effects in cognitive experiments.

    PubMed

    Semmelmann, Kilian; Weigelt, Sarah

    2016-08-05

    Using the Internet to acquire behavioral data is currently on the rise. However, very basic questions regarding the feasibility of online psychophysics are still open. Here, we aimed to replicate five well-known paradigms in experimental psychology (Stroop, Flanker, visual search, masked priming, attentional blink) in three settings (classical "lab", "web-in-lab", "web") to account for possible changes in technology and environment. Lab and web-in-lab data were both acquired in an in-lab setting with lab using "Gold Standard" methods, while web-in-lab used web technology. This allowed for a direct comparison of potential differences in acquisition software. To account for additional environmental differences, the web technology experiments were published online to participate from home (setting web), thereby keeping the software and experimental design identical and only changing the environmental setting. Our main results are: First, we found an expected fixed additive timing offset when using web technology (M = 37 ms, SD = 8.14) and recording online (M = 87 ms, SD = 16.04) in comparison to lab data. Second, all task-specific effects were reproduced except for the priming paradigm, which couldn't be replicated in any setting. Third, there were no differences in error rates, which are independent of the timing offset. This finding further supports the assumption of data equality over all settings. Fourth, we found that browser type might be influencing absolute reaction times. Together, these results contribute to the slowly but steadily growing literature that online psychophysics is a suitable complement - or even substitute - to lab data acquisition.

  4. Reaction Time Variability in HIV-Positive Individuals

    PubMed Central

    Ettenhofer, Mark L.; Foley, Jessica; Behdin, Nina; Levine, Andrew J.; Castellon, Steven A.; Hinkin, Charles H.

    2010-01-01

    Progression of HIV/AIDS is frequently associated with frontal/subcortical dysfunction and mean reaction time (RT) slowing. Beyond group means, within-subject variability of RT has been found to be particularly sensitive to frontal/subcortical dysfunction in other populations. However, the possible relevance of RT variability to HIV/AIDS patients remains unknown. This study evaluated the relationships between RT variability and indicators such as neurocognitive, behavioral, and immunological status. A total of 46 HIV-positive adults on antiretroviral medication regimens were included in this study. Overall performance of this sample was poorer than normative means on measures of RT latency, RT variability, and traditional neurocognitive domains. Results demonstrated that the measures of RT variability were associated with global cognition, medication adherence rates, and peak immunological dysfunction, above and beyond the effects of RT latency. These preliminary findings suggest that measures of RT variability may provide enhanced sensitivity to neurocognitive disease burden in HIV/AIDS relative to more traditional measures of mean RT or cognitive function. PMID:20798183

  5. 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…

  6. Automatic Activity and Reaction Time in Relation to Extraversion and Behavioral Impulsivity in Children and Adolescents.

    ERIC Educational Resources Information Center

    Zahn, Theodore P.; And Others

    1994-01-01

    Forty-five children and adolescents had skin conductance recorded during a presentation of tones and a reaction time test and were assessed for extraversion. Found that extraversion was negatively correlated with skin conductance response magnitudes to all stimuli--somewhat more strongly for reaction-time stimuli--and with reaction time. (HTH)

  7. Factoring out nondecision time in choice reaction time data: Theory and implications.

    PubMed

    Verdonck, Stijn; Tuerlinckx, Francis

    2016-03-01

    Choice reaction time (RT) experiments are an invaluable tool in psychology and neuroscience. A common assumption is that the total choice response time is the sum of a decision and a nondecision part (time spent on perceptual and motor processes). While the decision part is typically modeled very carefully (commonly with diffusion models), a simple and ad hoc distribution (mostly uniform) is assumed for the nondecision component. Nevertheless, it has been shown that the misspecification of the nondecision time can severely distort the decision model parameter estimates. In this article, we propose an alternative approach to the estimation of choice RT models that elegantly bypasses the specification of the nondecision time distribution by means of an unconventional convolution of data and decision model distributions (hence called the D*M approach). Once the decision model parameters have been estimated, it is possible to compute a nonparametric estimate of the nondecision time distribution. The technique is tested on simulated data, and is shown to systematically remove traditional estimation bias related to misspecified nondecision time, even for a relatively small number of observations. The shape of the actual underlying nondecision time distribution can also be recovered. Next, the D*M approach is applied to a selection of existing diffusion model application articles. For all of these studies, substantial quantitative differences with the original analyses are found. For one study, these differences radically alter its final conclusions, underlining the importance of our approach. Additionally, we find that strongly right skewed nondecision time distributions are not at all uncommon.

  8. 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…

  9. 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

  10. 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

  11. 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

  12. 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.

  13. Real-Time Polymerase Chain Reaction Assays for Rickettsial Diseases

    DTIC Science & Technology

    2004-06-01

    agents in the blood stream the diseases are also difficult to diagnose by laboratory methods. For that reason we have developed real - time PCR assays to...detect rickettsial disease agents both at the genus and the species level. Real - time PCR assays were developed to identify: 1) pathogenic Rickettsia...calculate the sensitivity of the assays. These real - time PCR assays were found to be capable of detecting rickettsial disease agents quickly and with great sensitivity and specificity.

  14. Are introspective reaction times affected by the method of time estimation? A comparison of visual analogue scales and reproduction.

    PubMed

    Bryce, Donna; Bratzke, Daniel

    2015-04-01

    In this study, we investigated whether the method of time estimation plays a role in the apparent limits of introspection in dual-task processing. Previous studies showed that when participants reported introspective reaction times after each trial of a dual task by clicking on a visual analogue scale, they appeared to be unaware of the dual-task costs in their performance. However, visual analogue scales have seldom been used in interval estimation, and they may be inappropriate. In the present study, after each dual-task trial, participants reported their introspective reaction times either via a visual analogue scale or via the method of reproduction. The results replicated the previous findings, irrespective of method. That is, even though responses to the second task slowed down with increasing task overlap, this slowing was only very weakly reflected in the introspective reaction times. Thus, the participants' failure to report the objective dual-task costs in their reaction times is a rather robust finding that cannot be attributed to the method employed. However, introspective reaction times reported via visual analogue scales were more closely related to the objective reaction times, suggesting that visual analogue scales are preferable to reproduction. We conclude that introspective reaction times represent the same information regardless of method, but whether that information is temporal in nature is as yet unsettled.

  15. In situ reaction furnace for real-time XRD studies.

    PubMed

    Riello, Pietro; Lausi, Andrea; Macleod, Jennifer; Plaisier, Jasper Rikkert; Zerauschek, Giulio; Fornasiero, Paolo

    2013-01-01

    The new furnace at the Materials Characterization by X-ray Diffraction beamline at Elettra has been designed for powder diffraction measurements at high temperature (up to 1373 K at the present state). Around the measurement region the geometry of the radiative heating element assures a negligible temperature gradient along the capillary and can accommodate either powder samples in capillary or small flat samples. A double capillary holder allows flow-through of gas in the inner sample capillary while the outer one serves as the reaction chamber. The furnace is coupled to a translating curved imaging-plate detector, allowing the collection of diffraction patterns up to 2θ ≃ 130°.

  16. 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.

  17. Timing of cortical excitability changes during the reaction time of movements superimposed on tonic motor activity.

    PubMed

    Schneider, Cyril; Lavoie, Brigitte A; Barbeau, Hugues; Capaday, Charles

    2004-12-01

    Seated subjects were instructed to react to an auditory cue by simultaneously contracting the tibialis anterior (TA) muscle of each ankle isometrically. Focal transcranial magnetic stimulation of the leg area of the motor cortex (MCx) was used to determine the time course of changes in motor-evoked potential amplitude (MEP) during the reaction time (RT). In one condition the voluntary contraction was superimposed on tonic EMG activity maintained at 10% of maximal voluntary contraction. In the other condition the voluntary contraction was made starting from rest. MEPs in the TA contralateral to the stimulation coil were evoked at various times during the RT in each condition. These were compared to the control MEPs evoked during tonic voluntary activity or with the subject at rest. The RT was measured trial by trial from the EMG activity of the TA ipsilateral to the magnetic stimulus, taking into account the nearly constant time difference between the two sides. The MEPs became far greater than control MEPs during the RT (mean = 332%, SD = 44 %, of control MEPs, P < 0.001) without any measurable change in the background level of EMG activity. The onset of this facilitation occurred on average 12.80 ms (SD = 7.55 ms) before the RT. There was no difference in the onset of facilitation between the two conditions. Because MEPs were facilitated without a change in the background EMG activity, it is concluded that this facilitation is specifically due to an increase of MCx excitability just before voluntary muscle activation. This conclusion is further reinforced by the observation that MEPs evoked by near-threshold anodal stimuli to the MCx were not facilitated during the RT, in contrast to those evoked by near-threshold transcranial magnetic stimulation. However, several observations in the present and previous studies indicate that MEP amplitude may be more sensitive to alpha-motoneuron activity than to motor cortical neuron activity, an idea that has important

  18. Exact Analytic Solution of the Non-Markovian Chemical Reaction Process Via Time-Subordination

    NASA Astrophysics Data System (ADS)

    Benson, D. A.

    2015-12-01

    Perfectly-mixed reactions are Markovian, because the advance of the state depends only on the current state. Poor mixing (or the partner process of upscaling over heterogeneous concentrations) renders the process non-Markovian because of memory of the chemical structure. In other words, a particle takes some time to reach a suitable reaction site. The time depends on structure, and the structure changes over time. For purely diffusive transport, a calculation of the random time to reach the edges of ``islands'' allows a solution of the non-Markovian reaction rates that evolve (decrease) over time. This randomization of the active (operational) reaction time leads to non-Markovian reactions and an integro-differential governing equation of chemical evolution. Implications for more complex (advection/diffusion) environments are discussed.

  19. 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.

  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. 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 ...

  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. A Comparative Study of Simple Auditory Reaction Time in Blind (Congenitally) and Sighted Subjects

    PubMed Central

    Gandhi, Pritesh Hariprasad; Gokhale, Pradnya A.; Mehta, H. B.; Shah, C. J.

    2013-01-01

    Background: Reaction time is the time interval between the application of a stimulus and the appearance of appropriate voluntary response by a subject. It involves stimulus processing, decision making, and response programming. Reaction time study has been popular due to their implication in sports physiology. Reaction time has been widely studied as its practical implications may be of great consequence e.g., a slower than normal reaction time while driving can have grave results. Objective: To study simple auditory reaction time in congenitally blind subjects and in age sex matched sighted subjects. To compare the simple auditory reaction time between congenitally blind subjects and healthy control subjects. Materials and Methods: Study had been carried out in two groups: The 1st of 50 congenitally blind subjects and 2nd group comprises of 50 healthy controls. It was carried out on Multiple Choice Reaction Time Apparatus, Inco Ambala Ltd. (Accuracy±0.001 s) in a sitting position at Government Medical College and Hospital, Bhavnagar and at a Blind School, PNR campus, Bhavnagar, Gujarat, India. Observations/Results: Simple auditory reaction time response with four different type of sound (horn, bell, ring, and whistle) was recorded in both groups. According to our study, there is no significant different in reaction time between congenital blind and normal healthy persons. Conclusion: Blind individuals commonly utilize tactual and auditory cues for information and orientation and they reliance on touch and audition, together with more practice in using these modalities to guide behavior, is often reflected in better performance of blind relative to sighted participants in tactile or auditory discrimination tasks, but there is not any difference in reaction time between congenitally blind and sighted people. PMID:24249930

  5. Real-time Detection of Polymerization Reactions with Hyperpolarized Xenon at Low Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Glöggler, Stefan; Blümich, Bernhard; Appelt, Stephan

    2011-03-01

    For process control it is desirable to develop simple devices for studying polymerization reactions in real-time and in-situ. We are demonstrating an approach using NMR at fields as low as 35 G and hyperpolarized xenon, which allows us to observe polymerization reactions in real-time. The investigated reaction is a free radical polymerization with the initiator azobisisobutyronitrile (AIBN) and the monomer methyl methacrylate (MMA). AIBN and MMA are mixed together in a sample tube under noble gas atmosphere, and the reaction is started by irradiation with UV light (360 nm). As the reaction goes on, xenon NMR spectra are acquired. They show increasing line broadening and a variation of the chemical shift depending on the state of polymerization. This observation gives rise to the idea that a single-sided high resolution NMR sensor can be developed with which at least light induced polymerization reactions can be studied in-situ and in real-time.

  6. Visual Acuity and Reaction Time in Navy Fighter Pilots,

    DTIC Science & Technology

    1986-12-01

    10. SOUR CW 0FUHND"N NUmIRs Naval Medical Research & Development Command PRGKOM POX ~JCT TASK WORK UNITI IIAMET NO Ný CESSION NO.NMC, National Capital...8. Stimulus sizes were specified in minutes of visual angle ( mva ), and target exposure time was 3 seconds. 2 kdditiotwl details concerning these...This test required the subject to press the joystick iWmmeiately at the appearance of a swrathreshold spot target (2 mva 4iame-. ter). Target

  7. The Acute Effects of Thyrotropin Releasing Hormone on Reaction Times.

    DTIC Science & Technology

    1982-12-01

    to thyroid patients. It has no long term side effects. It has been known to improve concentration, comprehension, self-confidence and energy level...and Sgt. Laura Howell for their work during the early mornings and occasional tedium that this long -running experiment produced. In addition, I wish to...error term . At one time in the experimentation, there was a shortage of the TRH supply and, as a result, seven of the ten subjects received saline for

  8. 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

  9. 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

  10. 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.

  11. 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

  12. 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

  13. 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.

  14. 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.

  15. [When time stops... Psychiatric reactions to deportation orders of unaccompanied children and teenagers seeking asylum].

    PubMed

    Christensen, A M; Lindskov, T

    2000-04-17

    Five cases of psychiatric disturbances in unaccompanied children who were refused political asylum are described. The children showed severe reactions with suicidal thoughts or psychosis, with a characteristic loss of perception of time during the long period of waiting for a decision. These children with severe reactions constituted a minority of the total who were refused asylum.

  16. Variable Time Normalization Analysis: General Graphical Elucidation of Reaction Orders from Concentration Profiles.

    PubMed

    Burés, Jordi

    2016-12-23

    The recent technological evolution of reaction monitoring techniques has not been paralleled by the development of modern kinetic analyses. The analyses currently used disregard part of the data acquired, thus requiring an increased number of experiments to obtain sufficient kinetic information for a given chemical reaction. Herein, we present a simple graphical analysis method that takes advantage of the data-rich results provided by modern reaction monitoring tools. This analysis uses a variable normalization of the time scale to enable the visual comparison of entire concentration reaction profiles. As a result, the order in each component of the reaction, as well as kobs  , is determined with just a few experiments using a simple and quick mathematical data treatment. This analysis facilitates the rapid extraction of relevant kinetic information and will be a valuable tool for the study of reaction mechanisms.

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

    PubMed Central

    Parker, Krystal L.; Alberico, Stephanie L.; Miller, Adam D.; Narayanan, Nandakumar 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

  18. Simplest chronoscope. III. Further comparisons between reaction times obtained by meterstick versus machine.

    PubMed

    Montare, Alberto

    2013-06-01

    The three classical Donders' reaction time (RT) tasks (simple, choice, and discriminative RTs) were employed to compare reaction time scores from college students obtained by use of Montare's simplest chronoscope (meterstick) methodology to scores obtained by use of a digital-readout multi-choice reaction timer (machine). Five hypotheses were tested. Simple RT, choice RT, and discriminative RT were faster when obtained by meterstick than by machine. The meterstick method showed higher reliability than the machine method and was less variable. The meterstick method of the simplest chronoscope may help to alleviate the longstanding problems of low reliability and high variability of reaction time performances; while at the same time producing faster performance on Donders' simple, choice and discriminative RT tasks than the machine method.

  19. The Effect of Sleep Deprivation on Choice Reaction Time and Anaerobic Power of College Student Athletes

    PubMed Central

    Taheri, Morteza; Arabameri, Elaheh

    2012-01-01

    Purpose The aim of this study was to determine the effect of one night's sleep deprivation on anaerobic performance and Reaction time of subjects in the morning of the following day. Methods Eighteen male college student athletes were studied twice in a balanced, randomized design. Subjects were measured for peak power, mean power and Reaction time. Results The performance showed no significant difference in both tests of anaerobic power (peak power, mean power) over the sleep deprivation period (P= 0.3; P= 0.4 respectively), but reaction time differed significantly from baseline (P=0.003). Results support the hypothesis that sleep serves a function of cognitive restitution, particularly in the maintenance of attentional mechanisms. In the light of the above considerations. Conclusions It was concluded that short-term sleep deprivation is not effective on anaerobic performance, but adversely affects cognitive function such as Reaction Time. PMID:22461961

  20. 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.

  1. Interaction between measurement time and observed Hugoniot cusp due to chemical reactions

    NASA Astrophysics Data System (ADS)

    McGrane, S. D.; Brown, K. E.; Bolme, C. A.; Moore, D. S.

    2017-01-01

    Chemistry occurring on picosecond timescales can be observed through ultrafast laser shock drive experiments that measure Hugoniot data and transient absorption. The shock stress needed to induce chemical reactions on picosecond time scales is significantly larger than the stress needed to induce reactions on nanosecond time scales typical of gas gun and explosively driven plate impact experiments. This discrepancy is consistent with the explanation that increased shock stress leads to increased temperature, which drives thermally activated processes at a faster rate. While the data are qualitatively consistent with the interpretation of thermally dominated reactions, they are not a critical test of this interpretation. In this paper, we review data from several shocked liquids that illustrate a Hugoniot cusp due to volume changing reactions that occurs at higher shock stress states in picosecond experiments than in nanosecond to microsecond experiments. We also correlate the observed Hugoniot cusp states with transient absorption changes that occur due to the buildup of reaction products.

  2. 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.

  3. The Effects of Differing Oxygen Concentrations on Reaction Time Performance at Altitude

    DTIC Science & Technology

    2014-12-04

    Naval Medical Research Unit Dayton THE EFFECTS OF DIFFERING OXYGEN CONCENTRATIONS ON REACTION TIME PERFORMANCE AT ALTITUDE William Becker...COVERED (from – to) 1 Jan 2014 – 1 Jan 2015 4. TITLE The Effects of Differing Oxygen Concentrations on Reaction Time Performance at Altitude 5a...11,000 ft) wherein an approximately 60% oxygen concentration is delivered, and a high altitude function, which delivers a 94% oxygen concentration

  4. 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…

  5. Real-time electron dynamics simulation of two-electron transfer reactions induced by nuclear motion

    NASA Astrophysics Data System (ADS)

    Suzuki, Yasumitsu; Yamashita, Koichi

    2012-04-01

    Real-time electron dynamics of two-electron transfer reactions induced by nuclear motion is calculated by three methods: the numerically exact propagation method, the time-dependent Hartree (TDH) method and the Ehrenfest method. We find that, as long as the nuclei move as localized wave packets, the TDH and Ehrenfest methods can reproduce the exact electron dynamics of a simple charge transfer reaction model containing two electrons qualitatively well, even when nonadiabatic transitions between adiabatic states occur. In particular, both methods can reproduce the cases where a complete two-electron transfer reaction occurs and those where it does not occur.

  6. 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.

  7. Finite-Time Stability Analysis of Reaction-Diffusion Genetic Regulatory Networks with Time-Varying Delays.

    PubMed

    Fan, Xiaofei; Zhang, Xian; Wu, Ligang; Shi, Michael

    2016-04-11

    This paper is concerned with the finite-time stability problem of the delayed genetic regulatory networks (GRNs) with reaction-diffusion terms under Dirichlet boundary conditions. By constructing a Lyapunov-Krasovskii functional including quad- slope integrations, we establish delay-dependent finite-time stabil- ity criteria by employing the Wirtinger-type integral inequality, Gronwall inequality, convex technique, and reciprocally convex technique. In addition, the obtained criteria are also reaction- diffusion-dependent. Finally, a numerical example is provided to illustrate the effectiveness of the theoretical results.

  8. 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.

  9. Study on simple reaction and choice times in patients with type I diabetes.

    PubMed

    Padilla-Medina, Jose A; Prado-Olivarez, Juan; Amador-Licona, Norma; Cardona-Torres, Luz M; Galicia-Resendiz, Delia; Diaz-Carmona, Javier

    2013-05-01

    A study on simple reaction time (SRT) and choice reaction time in patients having diabetes is described in this paper. The study was applied to fourteen patients with type I diabetes, as well as to fourteen non-diabetic persons. The research is based on two visual signal perception experiments, both implemented on a computer based environment. The SRT experiment consisted on measuring participants' reaction times to a light change event in a simulated traffic light scenario. The choice reaction time was studied through the performance indexes (d') achieved by participants in a two alternative forced experiment, where a known visual signal is identified from two noisy images. According to the obtained results, the diabetic patients' SRTs were an average of 24% longer than the reaction time of non-diabetic persons, in the same way a significant average difference of 41% was obtained in the efficient index d' too. A positive correlation of 0.6594 between the time periods since diabetes has been diagnosed and the average SRTs of diabetic patients was obtained, also significant correlation differences between age of all experiments participants and resulting variables, SRTs and d', were observed; for instance the correlation factor between participants' ages and their average SRTs was -0.8529 for diabetic patients, meanwhile a value of -0.2905 was obtained for non-diabetic persons. The evidence suggests that the time period since diabetes has been diagnosed notably affects motor and sensorial systems maturity, and consequently conduction speed of sural and peroneal nerves.

  10. 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

  11. Online Monitoring of Enzymatic Reactions Using Time-Resolved Desorption Electrospray Ionization Mass Spectrometry.

    PubMed

    Cheng, Si; Wu, Qiuhua; Xiao, He; Chen, Hao

    2017-02-21

    Electrospray ionization mass spectrometry (ESI-MS) is powerful for determining enzymatic reaction kinetics because of its soft ionization nature. However, it is limited to use ESI-favored solvents containing volatile buffers (e.g., ammonium acetate). In addition, lack of a quenching step for online ESI-MS reaction monitoring might introduce inaccuracy, due to the possible acceleration of reaction in the sprayed microdroplets. To overcome these issues, this study presents a new approach for online measuring enzymatic reaction kinetics using desorption electrospray ionization mass spectrometry (DESI-MS). By using DESI-MS, enzymatic reaction products in a buffered aqueous media (e.g., a solution containing Tris buffer or high concentration of inorganic salts) could be directly detected. Furthermore, by adjusting the pH and solvent composition of the DESI spray, reaction can be online quenched to avoid the postionization reaction event, leading to fast and accurate measurement of kinetic constants. Reaction time control can be obtained simply by adjusting the injection flow rates of enzyme and substrate solutions. Enzymatic reactions examined in this study include hydrolysis of 2-nitrophenyl-β-D-galactopyranoside by β-galactosidase and hydrolysis of acetylcholine by acetylcholinesterase. Derived Michaelis-Menten constants Km for these two reactions were determined to be 214 μM and 172 μM, respectively, which are in good agreement with the values of 300 μM and 230 μM reported in literature, validating the DESI-MS approach. Furthermore, this time-resolved DESI-MS also allowed us to determine Km and turnover number kcat for trypsin digestion of angiotensin II (Km and kcat are determined to be 6.4 mM and 1.3 s(-1), respectively).

  12. Extended kinetic model of real-time polymerase chain reaction process

    NASA Astrophysics Data System (ADS)

    Fedorov, A. A.; Sochivko, D. G.; Varlamov, D. A.; Kurochkin, V. E.

    2016-11-01

    Real-time polymerase chain reaction (real-time PCR) is the main molecular genetic method used for qualitative and quantitative analysis of specific nucleic acid sequences in many areas of biomedical research. Theoretical study of pCr models allows to estimate the influence of various reaction components and parameters, and to determine the unknown parameter values by approximating the experimental real-time PCR curves. An extended kinetic model of real-time PCR is presented. The model takes into account the enzyme activity based on Michaelis-Menten kinetics, the hybridization of complementary DNA fragments, the presence of a fluorescent probe used for detection of the reaction products, and the temperature dependence of primers and probe hybridization.

  13. 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.

  14. 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.

  15. 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.

  16. 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

  17. 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…

  18. 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.

  19. Changes in basal body temperature and simple reaction times during the menstrual cycle.

    PubMed

    Simić, Nataša; Ravlić, Arijana

    2013-01-01

    Previous studies have shown cyclic changes in the activation levels and performance of different tasks throughout the menstrual cycle. The aim of this study was to examine if changes in the reaction time to both light and sound stimuli may be associated with basal body temperature changes and subjective assessments of General and High Activation during the different phases of a menstrual cycle characterized by high (preovulatory and midluteal phase) and low (menstrual and early follicular phase) levels of oestrogen and progesterone. The study included measurements of basal body temperature, simple reaction times to light and sound and self-assessment of General and High Activation during the menstrual, early follicular, late follicular and luteal phase. The sample consisted of 19 female subjects with regular menstrual cycles. The results obtained in this study indicate lower basal body temperature values during phases with low sex hormone levels, while the activation assessments suggest stable levels of both General and High Activation throughout the menstrual cycle. Similar patterns of change have been shown for reaction times in visual and auditory sensory modalities. Reaction times were shorter during phases characterized by high sex hormone levels, while phases with low hormone levels were associated with longer reaction times. From the modified text on correlations in the data analysis section, it is evident that they were calculated from averaged data from all phases of the menstrual cycle. Therefore, they do not reflect intraindividual but rather interindividual variations between the observed variables, and are not related to the hypotheses of this paper.

  20. Striatal lesions produce distinctive impairments in reaction time performance in two different operant chambers.

    PubMed

    Brasted, P J; Döbrössy, M D; Robbins, T W; Dunnett, S B

    1998-08-01

    The dorsal striatum plays a crucial role in mediating voluntary movement. Excitotoxic striatal lesions in rats have previously been shown to impair the initiation but not the execution of movement in a choice reaction time task in an automated lateralised nose-poke apparatus (the "nine-hole box"). Conversely, when a conceptually similar reaction time task has been applied in a conventional operant chamber (or "Skinner box"), striatal lesions have been seen to impair the execution rather than the initiation of the lateralised movement. The present study was undertaken to compare directly these two results by training the same group of rats to perform a choice reaction time task in the two chambers and then comparing the effects of a unilateral excitotoxic striatal lesion in both chambers in parallel. Particular attention was paid to adopting similar parameters and contingencies in the control of the task in the two test chambers. After striatal lesions, the rats showed predominantly contralateral impairments in both tasks. However, they showed a deficit in reaction time in the nine-hole box but an apparent deficit in response execution in the Skinner box. This finding confirms the previous studies and indicates that differences in outcome are not simply attributable to procedural differences in the lesions, training conditions or tasks parameters. Rather, the pattern of reaction time deficit after striatal lesions depends critically on the apparatus used and the precise response requirements for each task.

  1. 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.

  2. 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.

  3. Analysis of Balance, Rapidity, Force and Reaction Times of Soccer Players at Different Levels of Competition

    PubMed Central

    Niosi, Alberto; Menciassi, Arianna

    2013-01-01

    In the present study we analyzed 12 physical parameters, namely force, static and dynamic balance (both quantified by means of 4 parameters each), rapidity, visual reaction times and acoustic reaction times, over 185 subjects. 170 of them played soccer in teams enrolled in all the ten different Italian soccer leagues. Results show that 6 parameters (out of the 12 analyzed) permit to identify and discriminate top-level players, among those showing the same training frequency. The other parameters are strictly related to training frequency or do not discriminate among players or control subjects (non-athletes), such as visual and acoustic reaction times. Principal component analysis permits to identify 4 clusters of subjects with similar performances, thus representing a useful instrument to characterize the overall ability of players in terms of athletic characteristics, on the basis of their location on the principal component parameters plane. PMID:24130870

  4. Predicting the human reaction time based on natural image statistics in a rapid categorization task.

    PubMed

    Mirzaei, Amin; Khaligh-Razavi, Seyed-Mahdi; Ghodrati, Masoud; Zabbah, Sajjad; Ebrahimpour, Reza

    2013-04-05

    The human visual system is developed by viewing natural scenes. In controlled experiments, natural stimuli therefore provide a realistic framework with which to study the underlying information processing steps involved in human vision. Studying the properties of natural images and their effects on the visual processing can help us to understand underlying mechanisms of visual system. In this study, we used a rapid animal vs. non-animal categorization task to assess the relationship between the reaction times of human subjects and the statistical properties of images. We demonstrated that statistical measures, such as the beta and gamma parameters of a Weibull, fitted to the edge histogram of an image, and the image entropy, are effective predictors of subject reaction times. Using these three parameters, we proposed a computational model capable of predicting the reaction times of human subjects.

  5. 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.

  6. Solving the Structure of Reaction Intermediates by Time-Resolved Synchrotron X-ray Absorption Spectroscopy

    SciTech Connect

    Wang, Q.; Hanson, J; Frenkel, A

    2008-01-01

    We present a robust data analysis method of time-resolved x-ray absorption spectroscopy experiments suitable for chemical speciation and structure determination of reaction intermediates. Chemical speciation is done by principal component analysis (PCA) of the time-resolved x-ray absorption near-edge structure data. Structural analysis of intermediate phases is done by theoretical modeling of their extended x-ray absorption fine-structure data isolated by PCA. The method is demonstrated using reduction and reoxidation of Cu-doped ceria catalysts where we detected reaction intermediates and measured fine details of the reaction kinetics. This approach can be directly adapted to many time-resolved x-ray spectroscopy experiments where new rapid throughput data collection and analysis methods are needed.

  7. 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.

  8. 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.

  9. A reaction kinetic approach to the temperature-time history of sedimentary basins

    NASA Astrophysics Data System (ADS)

    Sajgó, Cs.; Lefler, J.

    Three biological marker reactions have been studied in order to determine the temperature — time history of a sedimentary sequence. Two of these reactions are configurational isomerization reactions, at C-20 in a C29-sterane and at C-22 in C31 and C32 hopane hydrocarbons. In the third reaction two C29 C-ring monoaromatic steroid hydrocarbons convert to a C28 triaromatic one. The progress of these reactions is different because of their different rate constants. Based on temperature and age data obtained from field measurements and on concentration measurements of reactants and products in core samples of a Pannonian borehole, we calculated the rate parameters: pre-exponential factors, enthalpies and entropies of activation. It is obvious, that at least two different reactions are necessary to characterize the maturity of any system. The aromatization seems to be a rather complicated reaction, and we believe its use to be premature. Fortunately, two isomerizations work well and are suitable for elucidation of thermal history in different basins if the rate constants are universally valid.

  10. 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.

  11. 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.

  12. Postural stability, clicker reaction time and bow draw force predict performance in elite recurve archery.

    PubMed

    Spratford, Wayne; Campbell, Rhiannon

    2017-02-14

    Recurve archery is an Olympic sport that requires extreme precision, upper body strength and endurance. The purpose of this research was to quantify how postural stability variables both pre- and post-arrow release, draw force, flight time, arrow length and clicker reaction time, collectively, impacted on the performance or scoring outcomes in elite recurve archery athletes. Thirty-nine elite-level recurve archers (23 male and 16 female; mean age = 24.7 ± 7.3 years) from four different countries volunteered to participate in this study prior to competing at a World Cup event. An AMTI force platform (1000Hz) was used to obtain centre of pressure (COP) measurements 1s prior to arrow release and 0.5s post-arrow release. High-speed footage (200Hz) allowed for calculation of arrow flight time and score. Results identified clicker reaction time, draw force and maximum sway speed as the variables that best predicted shot performance. Specifically, reduced clicker reaction time, greater bow draw force and reduced postural sway speed post-arrow release were predictors of higher scoring shots. It is suggested that future research should focus on investigating shoulder muscle tremors at full draw in relation to clicker reaction time, and the effect of upper body strength interventions (specifically targeting the musculature around the shoulder girdle) on performance in recurve archers.

  13. 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

  14. 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.

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

    PubMed

    Yokochi, F; Nakamura, R; Narabayashi, H

    1985-07-01

    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.

  16. 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.

  17. 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

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

    PubMed

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

    2016-01-01

    Background. It is important to prepare response in advance to increase the efficiency of its execution. The process of response preparation is usually studied using the precueing paradigm. In this paradigm subjects have to employ the preceding information about further imperative stimulus to perform proper response preparation, which shortens the reaction time of subsequent response execution. Previous studies detected the impairment of response preparation in schizophrenia only with the help of electroencephalographic parameters, but not with the assessing of reaction time. Therefore, in this study we attempted to find a behavioural parameter that could detect impairment in response preparation of schizophrenia patients. It was recently found that appropriate response preparation not only shortens the reaction time but also increases its stability, which is measured with the intra-individual reaction time variability. It was also revealed that response stability could better find cognitive dysfunction in some studies of schizophrenia disorder than classical behavioural parameters. Hence, the main goal of this study was to verify if intra-individual reaction time variability could detect the impairment of response preparation in schizophrenia patients. Materials and methods. In order to achieve the main purpose, we carried out a study with 14 schizophrenia patients and 14 control group subjects. We used precueing paradigm in our research, in which participants had to employ information about stimulus probability for the proper response preparation. Results. Our main result showed that despite the responses of schizophrenia patients were faster to the high-probability stimulus than to the low-probability one (F (1, 13) = 30.9, p < 0.001), intra-individual reaction time variability did not differ in this group between the responses to more and less probable stimuli (F (1, 13) = 0.64, p = 0.44). Conclusions. Results of the study suggest that people with schizophrenia

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

    PubMed Central

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

    2016-01-01

    Background. It is important to prepare response in advance to increase the efficiency of its execution. The process of response preparation is usually studied using the precueing paradigm. In this paradigm subjects have to employ the preceding information about further imperative stimulus to perform proper response preparation, which shortens the reaction time of subsequent response execution. Previous studies detected the impairment of response preparation in schizophrenia only with the help of electroencephalographic parameters, but not with the assessing of reaction time. Therefore, in this study we attempted to find a behavioural parameter that could detect impairment in response preparation of schizophrenia patients. It was recently found that appropriate response preparation not only shortens the reaction time but also increases its stability, which is measured with the intra-individual reaction time variability. It was also revealed that response stability could better find cognitive dysfunction in some studies of schizophrenia disorder than classical behavioural parameters. Hence, the main goal of this study was to verify if intra-individual reaction time variability could detect the impairment of response preparation in schizophrenia patients. Materials and methods. In order to achieve the main purpose, we carried out a study with 14 schizophrenia patients and 14 control group subjects. We used precueing paradigm in our research, in which participants had to employ information about stimulus probability for the proper response preparation. Results. Our main result showed that despite the responses of schizophrenia patients were faster to the high-probability stimulus than to the low-probability one (F (1, 13) = 30.9, p < 0.001), intra-individual reaction time variability did not differ in this group between the responses to more and less probable stimuli (F (1, 13) = 0.64, p = 0.44). Conclusions. Results of the study suggest that people with schizophrenia

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

    NASA Astrophysics Data System (ADS)

    Mohamed, Norani Muti; Ahmad, Pervaiz; Saheed, Mohamed Shuaib Mohamed; Burhanudin, Zainal Arif

    2014-10-01

    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.

  1. ANAM4 TBI reaction time-based tests have prognostic utility for acute concussion.

    PubMed

    Norris, Jacob N; Carr, Walter; Herzig, Thomas; Labrie, D Walter; Sams, Richard

    2013-07-01

    The Concussion Restoration Care Center has used the Automated Neuropsychological Assessment Metrics version 4 Traumatic Brain Injury (ANAM4 TBI) battery in clinical assessment of concussion. The study's aim is to evaluate the prognostic utility of the ANAM4 TBI. In 165 concussed active duty personnel (all ultimately returned to duty) seen and tested on the ANAM4 TBI on days 3 and 5 (median times) from their injury, Spearman's ρ statistics showed that all performance subtests (at day 5) were associated with fewer days return-to-duty (RTD) time, whereas concussion history or age did not. Kruskal-Wallis statistics showed that ANAM4 TBI, loss of consciousness, and post-traumatic amnesia were associated with increased RTD time; ANAM4 TBI reaction time-based subtests, collectively, showed the largest effect sizes. A survival analysis using a Kaplan-Meier plot showed that the lowest 25% on the reaction time-based subtests had a median RTD time of 19 days, whereas those in the upper 25% had a median RTD time of approximately 7 days. Results indicate that until validated neurocognitive testing is introduced, the ANAM4 TBI battery, especially reaction time-based tests, has prognostic utility.

  2. Individual differences in components of reaction time distributions and their relations to working memory and intelligence.

    PubMed

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

    2007-08-01

    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 of the 3 ex-Gaussian parameters and for 3 parameters central to the diffusion model using structural equation modeling for a battery of choice reaction tasks. These factors had differential relations to criterion constructs. Parameters reflecting the tail of the distribution (i.e., tau in the ex-Gaussian and drift rate in the diffusion model) were the strongest unique predictors of working memory, reasoning, and psychometric speed. Theories of controlled attention and binding are discussed as potential theoretical explanations.

  3. Maturation conditions and boar affect timing of cortical reaction in porcine oocytes.

    PubMed

    Romar, R; Coy, P; Rath, D

    2012-09-15

    The cortical reaction induces changes at the egg's Zona pellucida (ZP), perivitelline space and/or oolemma level, blocking polyspermic fertilization. We studied the timing of sperm penetration and cortical reaction in pig oocytes matured under different conditions and inseminated with different boars. Immature (germinal vesicle stage) and in vitro matured (IVM) (metaphase II stage) oocytes were inseminated and results assessed at different hours post insemination. Penetrability and polyspermy rates increased with gamete coincubation time and were higher in IVM oocytes. A strong boar effect was observed in IVF results. Cortical reaction (assessed as area occupied by cortical granules) and galactose-β(1-3)-Nacetylgalactosamine residues on ZP (area labeled by peanut agglutinin lectin, PNA) were assessed in IVM and in vivo matured (IVV) oocytes at different hours post insemination. After maturation, IVM and IVV oocytes displayed similar area occupied by cortical granules and it decreased in fertilized oocytes compared to unfertilized ones. Cortical reaction was influenced by boar and was faster in polyspermic than in monospermic oocytes, and in IVM than in IVV oocytes. The outer ZP of inseminated oocytes appeared stained by PNA and the labeled area increased along with gamete coculture time. This labeling was also observed after insemination of isolated ZP, indicating that this modification in ZP carbohydrates is not induced by cortical reaction. The steady and maintained cortical reaction observed at 4 to 5 h post insemination in IVV monospermic oocytes might reflect the physiological time course of this important event in pigs. Both maturation conditions and boar affect cortical granules release.

  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. 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.

  6. 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…

  7. 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…

  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…

  9. Effect of musical expertise on visuospatial abilities: evidence from reaction times and mental imagery.

    PubMed

    Brochard, Renaud; Dufour, André; Després, Olivier

    2004-03-01

    Recently, the relationship between music and nonmusical cognitive abilities has been highly debated. It has been documented that formal music training would improve verbal, mathematical or visuospatial performance in children. In the experiments described here, we tested if visual perception and imagery abilities were enhanced in adult musicians compared with nonmusicians. In our main experiment, we measured reaction times of subjects who had to detect on which side of a horizontal or a vertical line a target dot was flashed. In the "imagery" condition the reference line disappeared before the target dot was presented. In order to accomplish the task, subjects had to keep a mental image of the position of the line until the dot appeared. In the "perception" condition, the procedure and stimuli were the same except that the line remained on the screen until the dot was displayed. In both groups, reaction times were shorter for horizontal compared to vertical discrimination, but reaction times were significantly shorter in musicians in all conditions. Moreover, discrimination on the vertical dimension, especially in imaging condition, seemed to be greatly improved on the long term by musical expertise. Simple and choice visual reaction times indicate that this advantage could only be partly explained by better sensorimotor integration in adult musicians.

  10. Placebo Effect upon Complex Reaction Time When Hypnotic Suggestibility is Controlled.

    ERIC Educational Resources Information Center

    Eskridge, Veronica L.

    This study was designed to investigate the effect of a placebo (sugar pill) accompanied by suggestions that the pill would either (1) improve performance as a stimulant or (2) cause a deterioration in performance as a depressant when the performance in question was the subjects' complex reaction time to a light stimulus. The Harvard Group Scale of…

  11. Brain Blood Flow Related to Acoustic Laryngeal Reaction Time in Adult Developmental Stutterers.

    ERIC Educational Resources Information Center

    Watson, Ben C.; And Others

    1992-01-01

    This study sought to identify patterns of impaired acoustic laryngeal reaction time as a function of response complexity parallel to metabolic measures of brain function. Findings indicated that the disruption in speech motor control for 16 adult male developmental stutterers was systematically related to metabolic asymmetry in left superior and…

  12. 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…

  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. 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…

  15. Reaction Time and Mortality from the Major Causes of Death: The NHANES-III Study

    PubMed Central

    Hagger-Johnson, Gareth; Deary, Ian J.; Davies, Carolyn A.; Weiss, Alexander; Batty, G. David

    2014-01-01

    Objective Studies examining the relation of information processing speed, as measured by reaction time, with mortality are scarce. We explored these associations in a representative sample of the US population. Methods Participants were 5,134 adults (2,342 men) aged 20–59 years from the Third National Health and Nutrition Examination Survey (NHANES III, 1988–94). Results Adjusted for age, sex, and ethnic minority status, a 1 SD slower reaction time was associated with a raised risk of mortality from all-causes (HR = 1.25, 95% CI 1.12, 1.39) and cardiovascular disease (CVD) (HR = 1.36, 95% CI 1.17, 1.58). Having 1 SD more variable reaction time was also associated with greater risk of all-cause (HR = 1.36, 95% CI 1.19, 1.55) and CVD (HR = 1.50, 95% CI 1.33, 1.70) mortality. No associations were observed for cancer mortality. The magnitude of the relationships was comparable in size to established risk factors in this dataset, such as smoking. Interpretation Alongside better-established risk factors, reaction time is associated with increased risk of premature death and cardiovascular disease. It is a candidate risk factor for all-cause and cause-specific mortality. PMID:24489645

  16. 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…

  17. 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…

  18. Reaction Times inaa Bisensory Task: Implications for Attention and Speech Perception

    ERIC Educational Resources Information Center

    Mynatt, Barbee T.

    1977-01-01

    Reading reaction time (RT) to visual stimuli was shown to vary according to the nature of simultaneous auditory stimuli. A two-stage model was proposed to explain the results in which parallel processing of simultaneous input occurs prior to a decision-making stage. (Editor)

  19. 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…

  20. Use of enrichment real time-Polymerase Chain Reaction to enumerate Salmonella on chicken parts

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Salmonella that survive cooking and that cross-contaminate other food during meal preparation and serving represent primary routes of consumer exposure to this pathogen from chicken. Consequently, the present study was undertaken to use enrichment real time-polymerase chain reaction (RT-PCR) to enu...

  1. 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…

  2. Implementation of Ion/Ion Reactions in a Quadrupole/Time-of-Flight Tandem Mass Spectrometer

    PubMed Central

    Xia, Yu; Chrisman, Paul A.; Erickson, David E.; Liu, Jian; Liang, Xiaorong; Londry, Frank A.; Yang, Min J.; McLuckey, Scott A.

    2008-01-01

    A commercial quadrupole/time-of-flight (QqTOF) tandem mass spectrometer has been adapted for ion/ion reaction studies. To enable mutual storage of oppositely charged ions in a linear ion trap, the oscillating quadrupole field of the second quadrupole of the system (Q2) serves to store ions in the radial dimension while auxiliary RF is superposed on the end lenses of Q2 during the reaction period to create barriers in the axial dimension. A pulsed dual electrospray (ESI) source is directly coupled to the instrument interface for the purpose of proton transfer reactions. Singly and doubly charged protein ions as high in mass as 66 kDa are readily formed and observed after proton transfer reactions. For the modified instrument, the mass resolving power is about 8000 for a wide m/z range and the mass accuracy is ~20 ppm for external calibration and ~5 ppm for internal calibration after ion/ion reactions. Parallel ion parking is demonstrated with a six-component protein mixture, which shows the potential application of reducing spectral complexity and concentrating certain charge states. The current system has high flexibility with respect to defining MSn experiments involving collision-induced dissociation (CID) and ion/ion reactions. Protein precursor and CID product masses can be determined with good accuracy, providing an attractive platform for top-down proteomics. Electron transfer dissociation (ETD) ion/ion reactions are implemented by using a pulsed nano-ESI/atmospheric pressure chemical ionization (APCI) dual source for ionization. The reaction between protonated peptide ions and radical anions of 1,3-dinitrobenzene formed exclusively c- and z- type fragment ions. PMID:16771545

  3. Reaction time and movement velocity abnormalities in Parkinson's disease under different task conditions.

    PubMed

    Montgomery, E B; Nuessen, J; Gorman, D S

    1991-09-01

    We examined reaction times, movement velocities, and the associated agonist and antagonist muscle behaviors in nine Parkinson's disease (PD) patients and eight normal subjects before and after medications, using a wrist extension task to changing locations of a visual target. Targets changing 500 msec before an auditory "go" signal act as a preparatory cue, while targets changing at the time of the go signal provide a combined auditory and visual stimulus. Late target changes allowed examination of (1) reaction times during an ongoing movement, and (2) movement in the presence and absence of visual targets. PD prolonged the time from the onset agonist electromyographic activity and reduction of antagonist activity to movement onset. Both were shortened by preparatory cues and combined visual and auditory go signals. PD slowed movement only in a subset of trials in which there was movement to a displayed target.

  4. 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

  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. Can a Clinical Test of Reaction Time Predict a Functional Head-Protective Response?

    PubMed Central

    ECKNER, JAMES T.; LIPPS, DAVID B.; KIM, HOGENE; RICHARDSON, JAMES K.; ASHTON-MILLER, JAMES A.

    2015-01-01

    Purpose Reaction time is commonly prolonged after a sport-related concussion. Besides being a marker for injury, a rapid reaction time is necessary for protective maneuvers that can reduce the frequency and severity of additional head impacts. The purpose of this study was to determine whether a clinical test of simple visuomotor reaction time predicted the time taken to raise the hands to protect the head from a rapidly approaching ball. Methods Twenty-six healthy adult participants recruited from campus and community recreation and exercise facilities completed two experimental protocols during a single session: a manual visuomotor simple reaction time test (RTclin) and a sport-related head-protective response (RTsprt). RTclin measured the time required to catch a thin vertically oriented device on its release by the tester and was calculated from the distance the device fell before being arrested. RTsprt measured the time required to raise the hands from waist level to block a foam tennis ball fired toward the subject’s face from an air cannon and was determined using an optoelectronic camera system. A correlation coefficient was calculated between RTclin and RTsprt, with linear regression used to assess for effect modification by other covariates. Results A strong positive correlation was found between RTclin and RTsprt (r = 0.725, P < 0.001) independent of age, gender, height, or weight. Conclusions RTclin is predictive of a functional sport-related head-protective response. To our knowledge, this is the first demonstration of a clinical test predicting the ability to protect the head in a simulated sport environment. This correlation with a functional head-protective response is a relevant consideration for the potential use of RTclin as part of a multifaceted concussion assessment program. PMID:20689458

  7. A multi-time-scale analysis of chemical reaction networks: II. Stochastic systems.

    PubMed

    Kan, Xingye; Lee, Chang Hyeong; Othmer, Hans G

    2016-11-01

    We consider stochastic descriptions of chemical reaction networks in which there are both fast and slow reactions, and for which the time scales are widely separated. We develop a computational algorithm that produces the generator of the full chemical master equation for arbitrary systems, and show how to obtain a reduced equation that governs the evolution on the slow time scale. This is done by applying a state space decomposition to the full equation that leads to the reduced dynamics in terms of certain projections and the invariant distributions of the fast system. The rates or propensities of the reduced system are shown to be the rates of the slow reactions conditioned on the expectations of fast steps. We also show that the generator of the reduced system is a Markov generator, and we present an efficient stochastic simulation algorithm for the slow time scale dynamics. We illustrate the numerical accuracy of the approximation by simulating several examples. Graph-theoretic techniques are used throughout to describe the structure of the reaction network and the state-space transitions accessible under the dynamics.

  8. Spike-triggered reaction-time EEG as a possible assessment tool for driving ability.

    PubMed

    Krestel, Heinz E; Nirkko, Arto; von Allmen, Andreas; Liechti, Christian; Wettstein, Janine; Mosbacher, Antoinette; Mathis, Johannes

    2011-10-01

    The impact of interictal epileptic activity (IEA) on driving is a rarely investigated issue. We analyzed the impact of IEA on reaction time in a pilot study. Reactions to simple visual stimuli (light flash) in the Flash test or complex visual stimuli (obstacle on a road) in a modified car driving computer game, the Steer Clear, were measured during IEA bursts and unremarkable electroencephalography (EEG) periods. Individual epilepsy patients showed slower reaction times (RTs) during generalized IEA compared to RTs during unremarkable EEG periods. RT differences were approximately 300 ms (p < 0.001) in the Flash test and approximately 200 ms (p < 0.001) in the Steer Clear. Prior work suggested that RT differences >100 ms may become clinically relevant. This occurred in 40% of patients in the Flash test and in up to 50% in the Steer Clear. When RT were pooled, mean RT differences were 157 ms in the Flash test (p < 0.0001) and 116 ms in the Steer Clear (p < 0.0001). Generalized IEA of short duration seems to impair brain function, that is, the ability to react. The reaction-time EEG could be used routinely to assess driving ability.

  9. Visualizing solution-phase reaction dynamics with time-resolved X-ray liquidography.

    PubMed

    Ihee, Hyotcherl

    2009-02-17

    Most chemical reactions occur in solution, and complex interactions between solute and solvent influence the rich chemistry of these processes. To track time-dependent processes in such reactions, researchers often use time-resolved spectroscopy. In these experiments, an optical pulse (pump) initiates a reaction, and another time-delayed optical pulse (probe) monitors the progress of the reaction. However, because of the wavelength range of the probe light used in these experiments, from infrared to ultraviolet, researchers cannot directly determine detailed structural information such as the bond lengths and bond angles of reaction intermediates. In addition, not all intermediates might be sensitive to the spectroscopic signal chosen for the experiment. This Account describes time-resolved X-ray liquidography (TRXL), a technique that overcomes these problems. In this technique, we replace the optical probe with the diffraction of hard X-ray pulses emitted from a synchrotron source. In TRXL, diffraction signals are sensitive to all chemical species simultaneously. In addition, each chemical species has a characteristic diffraction signal, a fingerprint, that we calculate from its three-dimensional atomic coordinates. Because, X-rays scatter from all atoms in the solution sample, including both the solute and the solvent, the analysis of TRXL data can track not only the reaction pathways of the solute molecules but also the solvent behavior and the solute-solvent arrangement, thus providing a global picture of the reactions. We have used TRXL to study structural dynamics and spatiotemporal kinetics of many molecular systems including diatomic molecules, haloalkanes, organometallic complexes, and protein molecules over timescales from picoseconds to milliseconds. We have observed that TRXL data adds to and, in some cases, contradicts results from time-resolved spectroscopy. For example, TRXL has shown that the reaction intermediates upon C-I bond dissociation in C(2

  10. New Pathways and Time-resolved Vibrational Dynamics of Surface Reactions

    NASA Astrophysics Data System (ADS)

    Wolf, Martin

    2000-03-01

    We discuss recent results of femtosecond laser-induced reactions and time-resolved vibrational spectroscopy at metal surfaces which provide detailed insights into the microscopic reaction mechanism and the rate of energy flow between the adsorbate and the underlying substrate. We demonstrate that fs laser excitation allows to access new reaction pathways which cannot be induced with conventional thermal activation: Heating of a Ru(001) surface on which CO and atomic oxygen are co-adsorbed leads exclusively to desorption of CO. In contrast, excitation with intense fs laser pulses enables also the formation of CO_2, in addition to CO desorption. Thus a new reaction path is opened upon fs laser excitation. Time-resolved two-pulse-correlation and isotope substitution experiments as well as density functional calculations reveal that this novel reaction pathway is initiated by laser heated hot substrate electrons which populate an antibonding unoccupied state of the O-Ru bond. The vibrationally activated oxygen reacts with co-adsorbed CO on an ultrashort time scale. On the other hand, desorption of CO molecules is caused by coupling of the adsorbate to the phonon bath of the substrate, which occurs much slower than the hot electron driven CO2 formation. Thus under fs excitation the process of CO desorption is outpaced, but prevails for conventional thermal heating due to a lower activation energy. In a further set of experiments the technique of fs infrared-visible sum-frequency generation (SFG) has been used as a time-resolved molecule specific 'probe' to analyze the transient changes of the CO stretching mode on Ru(001) after excitation with an intense fs 'pump' pulse. At low CO coverages the broadband infrared laser pulses also allow to excite the overtones of the CO stretch.

  11. 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.

  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. 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.

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

    PubMed

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

    2012-01-01

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

  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. 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.

  17. 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.

  18. Characterizing Information Processing With a Mobile Device: Measurement of Simple and Choice Reaction Time.

    PubMed

    Burke, Daniel; Linder, Susan; Hirsch, Joshua; Dey, Tanujit; Kana, Daniel; Ringenbach, Shannon; Schindler, David; Alberts, Jay

    2016-03-01

    Information processing is typically evaluated using simple reaction time (SRT) and choice reaction time (CRT) paradigms in which a specific response is initiated following a given stimulus. The measurement of reaction time (RT) has evolved from monitoring the timing of mechanical switches to computerized paradigms. The proliferation of mobile devices with touch screens makes them a natural next technological approach to assess information processing. The aims of this study were to determine the validity and reliability of using of a mobile device (Apple iPad or iTouch) to accurately measure RT. Sixty healthy young adults completed SRT and CRT tasks using a traditional test platform and mobile platforms on two occasions. The SRT was similar across test modality: 300, 287, and 280 milliseconds (ms) for the traditional, iPad, and iTouch, respectively. The CRT was similar within mobile devices, though slightly faster on the traditional: 359, 408, and 384 ms for traditional, iPad, and iTouch, respectively. Intraclass correlation coefficients ranged from 0.79 to 0.85 for SRT and from 0.75 to 0.83 for CRT. The similarity and reliability of SRT across platforms and consistency of SRT and CRT across test conditions indicate that mobile devices provide the next generation of assessment platforms for information processing.

  19. [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.

  20. Study of reaction time to visual stimuli in athletes with and without a hearing impairment.

    PubMed

    Soto-Rey, Javier; Pérez-Tejero, Javier; Rojo-González, Jesús J; Reina, Raúl

    2014-08-01

    This study analyzes the differences in manual reaction time (RT) to visual stimuli in two samples of physically active persons: a group of athletes without hearing impairment (n = 79; M age = 22.6 yr., SD = 3.7) and a group of athletes with hearing impairment (n = 44, M age = 25.6 yr., SD = 5.0). Reaction time (RT) was measured and then differences between both groups were assessed by sex, type of sport (individual vs team sports), and competition level. RT to visual stimuli was significantly shorter for athletes with hearing impairment than for those without hearing impairment, with a significant sex difference (shorter RT for males), but no differences regarding type of sport or competition level. Suggestions for further research and sport applications are provided.

  1. Intraindividual reaction time variability affects P300 amplitude rather than latency

    PubMed Central

    Ramchurn, Anusha; de Fockert, Jan W.; Mason, Luke; Darling, Stephen; Bunce, David

    2014-01-01

    The neural correlates of intraindividual response variability were investigated in a serial choice reaction time (CRT) task. Reaction times (RTs) from the faster and slower portions of the RT distribution for the task were separately aggregated and associated P300 event-related potentials computed. Independent behavioral measures of executive function and IQ were also recorded. Across frontal, fronto-central, central, centro-parietal and parietal scalp regions, P300 amplitudes were significantly greater for faster relative to slower behavioral responses. However, P300 peak amplitude latencies did not differ according to the speed of the behavioral RT. Importantly, controlling for select independent measures of executive function attenuated shared variance in P300 amplitude for faster and slower trials. The findings suggest that P300 amplitude rather than latency is associated with the speed of behavioral RTs, and the possibility that fluctuations in executive control underlie variability in speeded responding. PMID:25120458

  2. Associations between reaction time measures and white matter hyperintensities in very old age.

    PubMed

    Haynes, Becky I; Bunce, David; Kochan, Nicole A; Wen, Wei; Brodaty, Henry; Sachdev, Perminder S

    2017-02-01

    In old age, a relationship has been reported between intraindividual variability (IIV) in reaction time and white matter integrity as evidenced by white matter hyperintensities (WMH). However, it is unclear how far such associations are due to incipient neurodegenerative pathology in the samples investigated. The present study examined the relationship between IIV and WMH in older individuals (N=526) drawn from the Sydney Memory and Ageing Study. Using a complex reaction time (RT) task, greater IIV and mean-RT were related to a higher WMH burden in the frontal lobe. Critically, significant associations remained having taken future dementia into account suggesting that they were not explained by incipient dementia. Additionally, independent measures of executive function accounted for the association between RT metrics and WHM. The results are consistent with the view that frontally-supported cognitive processes are involved in IIV-WMH relations, and that RT measures are sensitive to compromise in white matter structures in non-demented older individuals.

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

    PubMed

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

    2010-01-01

    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 years; n = 24) and older (70-85 years; 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 = .51; motor inhibition: r = .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.

  4. A time-dependent quantum dynamical study of the H + HBr reaction.

    PubMed

    Fu, Bina; Zhang, Dong H

    2007-09-27

    Time-dependent wave packet calculations were carried out to study the exchange and abstraction processes in the title reaction on the Kurosaki-Takayanagi potential energy surface (Kurosaki, Y.; Takayanagi, T. J. Chem. Phys. 2003, 119, 7838). Total reaction probabilities and integral cross sections were calculated for the reactant HBr initially in the ground state, first rotationally excited state, and first vibrationally excited state for both the exchange and abstraction reactions. At low collision energy, only the abstraction reaction occurs because of its low barrier height. Once the collision energy exceeds the barrier height of the exchange reaction, the exchange process quickly becomes the dominant process presumably due to its larger acceptance cone. It is found that initial vibrational excitation of HBr enhances both processes, while initial rotational excitation of HBr from j(0) = 0 to 1 has essentially no effect on both processes. For the abstraction reaction, the theoretical cross section at E(c) = 1.6 eV is 1.06 A(2), which is smaller than the experimental result of 3 +/- 1 A(2) by a factor of 2-3. On the other hand, the theoretical rate constant is larger than the experimental results by about a factor of 2 in the temperature region between 220 and 550 K. It is also found that the present quantum rate constant is larger than the TST result by a factor of 2 at 200 K. However, the agreement between the present quantum rate constant and the TST result improves as the temperature increases.

  5. 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

  6. Separable responses to error, ambiguity, and reaction time in cingulo-opercular task control regions.

    PubMed

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

    2014-10-01

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

  7. 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

  8. Gold nanoparticle-enabled real-time ligation chain reaction for ultrasensitive detection of DNA.

    PubMed

    Shen, Wei; Deng, Huimin; Gao, Zhiqiang

    2012-09-12

    A simple and ultrasensitive colorimetric DNA assay based on the detection of the product of a ligation chain reaction (LCR) and the use of gold nanoparticles (AuNPs) as signal generators has been developed. During LCR, the AuNPs were ligated together, resulting in a distinct color change in real time after a sufficient number of thermal cycles. The cumulative nature of the protocol produced a detection limit of 20 aM with a selectivity factor of 10(3).

  9. 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…

  10. Reaction times in visual search can be explained by a simple model of neural synchronization.

    PubMed

    Kazanovich, Yakov; Borisyuk, Roman

    2017-03-01

    We present an oscillatory neural network model that can account for reaction times in visual search experiments. The model consists of a central oscillator that represents the central executive of the attention system and a number of peripheral oscillators that represent objects in the display. The oscillators are described as generalized Kuramoto type oscillators with adapted parameters. An object is considered as being included in the focus of attention if the oscillator associated with this object is in-phase with the central oscillator. The probability for an object to be included in the focus of attention is determined by its saliency that is described in formal terms as the strength of the connection from the peripheral oscillator to the central oscillator. By computer simulations it is shown that the model can reproduce reaction times in visual search tasks of various complexities. The dependence of the reaction time on the number of items in the display is represented by linear functions of different steepness which is in agreement with biological evidence.

  11. Effects of subthalamic nucleus stimulation on characteristics of EMG activity underlying reaction time in Parkinson's disease.

    PubMed

    Kumru, Hatice; Summerfield, Christopher; Valldeoriola, Francesc; Valls-Solé, Josep

    2004-01-01

    We examined the effects of high-frequency deep brain stimulation of the subthalamic nucleus (STN-DBS) on characteristics of electromyographic (EMG) activity of the agonist muscle in 8 patients with Parkinson's disease (PD). Patients were examined during STN-DBS (ON), and 30 minutes after switching off both stimulators (OFF). They were asked to make a ballistic movement in paradigms of simple reaction time (SRT) and choice reaction time (CRT) tasks. Onset of movement (MOVonset) was measured as the latency of the initial displacement from baseline of the signal from an accelerometer attached to the dorsum of the hand. In the associated EMG activity, recorded from wrist extensor muscles, we measured onset latency (EMGonset), size of the first EMG burst (EMGsize), and number of EMG bursts (EMGbursts) counted between EMGonset and task execution. MOVonset and EMGonset were significantly shorter in ON than in OFF conditions in CRT. EMGsize was larger, EMGbursts were reduced, and peak of the acceleration profile was larger in ON compared with OFF conditions in both SRT and CRT. Our results indicate that STN-DBS induces a significant improvement in motor performance of reaction time tasks in PD patients. Such improvement is associated with a change in features of the EMG activity suggesting an increase in the excitability of the motor pathways engaged in ballistic movements.

  12. 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.

  13. 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.

  14. Real-time investigations of selenization reactions in the system Cu-In-Al-Se

    NASA Astrophysics Data System (ADS)

    Jost, Stefan; Hergert, Frank; Hock, Rainer; Purwins, Michael; Enderle, Ralph

    2006-09-01

    In this article we present results of a detailed study of selenization reactions in the quaternary system Cu-In-Al-Se and of the binary subsystem aluminum-selenium. The investigation of solid-state reactions involved in the formation of the compound semiconductor Cu(In,Al)Se2 was performed using real-time X-ray diffraction (XRD) with a time resolution of 22.5 s while annealing an elemental layer stack of the metals covered with selenium. A temperature-resolved phase analysis shows that the formation of the semiconductor takes place via metal-selenides. Ex-situ XRD measurements of the processed thin films show a phase segregation concerning the aluminum content of the formed chalcopyrite. Subsequent Rietveld-refinement of real-time measurements reveals a formation reaction of the quaternary semiconductor Cu(In,Al)Se2 from the -In2Se3 related crystal structure of (Al,In)2Se3 and Cu2Se as educts.

  15. 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.

  16. Ayurvedic approach for improving reaction time of attention deficit hyperactivity disorder affected children

    PubMed Central

    Singhal, Harish Kumar; Neetu; Kumar, Abhimanyu; Rai, Moti

    2010-01-01

    Attention deficit/hyperactivity disorder (ADHD) is a behavioral disorder of children. It is the most common neurological disorder of childhood. The present study was conducted to examine the increase in attention span in 43 ADHD-affected children treated with different approaches. The reaction time was measured using a Vernier chronoscope (electronic). Selected children of both sexes in the age-group of 6–16 years were divided into three groups. In group A, 17 patients received syrup Ayurvedic compound I; in group B, 14 patients were treated with syrup Ayurvedic compound I + Shirodhara with milk; and in group C, 12 patients received syrup Ayurvedic compound II (placebo). The dose of the drug was 1.0 ml/kg body weight and the duration of treatment was 3 months. Group B showed highly significant (P<.001) improvement in total reaction time, while in group C the change was statistically nonsignificant P > 0.10. It was found that while the drug and Shirodhara were both effective in improving the reaction time of ADHD-affected children, the drug combined with Shirodhara was superior to the drug used alone. PMID:22131736

  17. 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

    2016-02-23

    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.

  18. Influence of seasonal timing on thermal ecology and thermal reaction norm evolution in Wyeomyia smithii.

    PubMed

    Ragland, G J; Kingsolver, J G

    2007-11-01

    Evolutionary changes in the seasonal timing of life-history events can alter a population's exposure to seasonally variable environmental factors. We illustrate this principle in Wyeomyia smithii by showing that: (1) geographic divergence in diapause timing reduces differences among populations in the thermal habitat experienced by nondiapause stages; and (2) the thermal habitat of the growing season is more divergent at high compared with low temperatures with respect to daily mean temperatures. Geographic variation in thermal reaction norms for development time was greater in a warm compared with a cool rearing treatment, mirroring the geographic trend in daily mean temperature. Geographic variation in body size was unrelated to geographic temperature variation, but was also unrelated to development time or fecundity. Our results suggest that proper interpretation of geographic trends may often require detailed knowledge of life-history timing.

  19. 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

  20. Designing driver assistance systems with crossmodal signals: multisensory integration rules for saccadic reaction times apply.

    PubMed

    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.

  1. [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%.

  2. Covert attention regulates saccadic reaction time by routing between different visual-oculomotor pathways.

    PubMed

    Guan, Shaobo; Liu, Yu; Xia, Ruobing; Zhang, Mingsha

    2012-03-01

    Covert attention modulates saccadic performance, e.g., the abrupt onset of a task-irrelevant visual stimulus grabs attention as measured by a decrease in saccadic reaction time (SRT). The attentional advantage bestowed by the task-irrelevant stimulus is short-lived: SRT is actually longer ~200 ms after the onset of a stimulus than it is when no stimulus appears, known as inhibition of return. The mechanism by which attention modulates saccadic reaction is not well-understood. Here, we propose two possible mechanisms: by selective routing of the visuomotor signal through different pathways (routing hypothesis) or by general modulation of the speed of visuomotor transformation (shifting hypothesis). To test them, we designed a cue gap paradigm in which a 100-ms gap was introduced between the fixation point disappearance and the target appearance to the conventional cued visual reaction time paradigm. The cue manipulated the location of covert attention, and the gap interval resulted in a bimodal distribution of SRT, with an early mode (express saccade) and a late mode (regular saccade). The routing hypothesis predicts changes in the proportion of express saccades vs. regular saccades, whereas the shifting hypothesis predicts a shift of SRT distribution. The addition of the cue had no effect on mean reaction time of express and regular saccades, but it changed the relative proportion of two modes. These results demonstrate that the covert attention modification of the mean SRT is largely attributed to selective routing between visuomotor pathways rather than general modulation of the speed of visuomotor transformation.

  3. Moments of action provide insight into critical times for advection-diffusion-reaction processes.

    PubMed

    Ellery, Adam J; Simpson, Matthew J; McCue, Scott W; Baker, Ruth E

    2012-09-01

    Berezhkovskii and co-workers introduced the concept of local accumulation time as a finite measure of the time required for the transient solution of a reaction-diffusion equation to effectively reach steady state [Biophys J. 99, L59 (2010); Phys. Rev. E 83, 051906 (2011)]. Berezhkovskii's approach is a particular application of the concept of mean action time (MAT) that was introduced previously by McNabb [IMA J. Appl. Math. 47, 193 (1991)]. Here, we generalize these previous results by presenting a framework to calculate the MAT, as well as the higher moments, which we call the moments of action. The second moment is the variance of action time, the third moment is related to the skew of action time, and so on. We consider a general transition from some initial condition to an associated steady state for a one-dimensional linear advection-diffusion-reaction partial differential equation (PDE). Our results indicate that it is possible to solve for the moments of action exactly without requiring the transient solution of the PDE. We present specific examples that highlight potential weaknesses of previous studies that have considered the MAT alone without considering higher moments. Finally, we also provide a meaningful interpretation of the moments of action by presenting simulation results from a discrete random-walk model together with some analysis of the particle lifetime distribution. This work shows that the moments of action are identical to the moments of the particle lifetime distribution for certain transitions.

  4. 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

  5. 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

  6. Reaction mechanisms and their interaction time in dissipative heavy-ion collisions

    SciTech Connect

    De Rosa, A.; Fioretto, E.; Inglima, G.; Romoli, M.; Sandoli, M.; Setola, R. ); Cardella, G.; Papa, M.; Pappalardo, G.; Rizzo, F.; Wang, Q. ); Napoli, D.R.; Scarlassara, F.; Segato, G.F.; Signorini, C.; Stefanini, A.M. )

    1990-05-01

    Angular distributions of fragments emitted in the reaction {sup 19}F+{sup 63}Cu measured in the range {theta}{sub lab}=10{degree} to 120{degree} at incident energy between 100 to 108 MeV (lab) have been analyzed according to available models for deep inelastic collisions with the aim to evidence different mechanisms contributing to such reactions. The analysis was performed in the framework of Strutinsky model taking into account both the development of Kun and of Abul-Magd and Simbel. To determine the interaction times, previously published excitation functions were also analyzed in the framework of Kun's model of cross section statistical fluctuations and near-side and far-side scattering were taken into account separately. It was pointed out that the rotational energy dissipation occurs in a limited angular range around the grazing angle. The presence of two distinct reaction mechanisms, each of them characterized by an interaction time, was also evidenced by comparing the energy averaged angular distributions to the Abul-Magd and Simbel model for dissipative collisions.

  7. Active Target-Time Projection Chambers for Reactions Induced by Rare Isotope Beams: Physics and Technology

    NASA Astrophysics Data System (ADS)

    Mittig, Wolfgang

    2013-04-01

    Weakly bound nuclear systems can be considered to represent a good testing-ground of our understanding of non-perturbative quantum systems. Great progress in experimental sensitivity has been attained by increase in rare isotope beam intensities and by the development of new high efficiency detectors. It is now possible to study reactions leading to bound and unbound states in systems with very unbalanced neutron to proton ratios. Application of Active Target-Time Projection Chambers to this domain of physics will be illustrated by experiments performed with existing detectors. The NSCL is developing an Active Target-Time Projection Chamber (AT-TPC) to be used to study reactions induced by rare isotope beams at the National Superconducting Cyclotron Facility (NSCL) and at the future Facility for Rare Isotope Beams (FRIB). The AT-TPC counter gas acts as both a target and detector, allowing investigations of fusion, isobaric analog states, cluster structure of light nuclei and transfer reactions to be conducted without significant loss in resolution due to the thickness of the target. The high efficiency and low threshold of the AT-TPC will allow investigations of fission barriers and giant resonances with fast fragmentation rare isotope beams. This detector type needs typically a large number of electronic channels (order of magnitude 10,000) and a high speed DAQ. A reduced size prototype detector with prototype electronics has been realized and used in several experiments. A short description of other detectors of this type under development will be given.

  8. 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

  9. 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.

  10. An examination by forearm EMG on pain reaction time to radiant heat.

    PubMed

    Hatayama, T; Shimizu, K

    1993-06-01

    The present study was done to estimate rise in skin temperature during a pain reaction time (pain RT) as a means of investigating why a pricking pain threshold, produced by thermal stimulation using time method, often increases during repeated measurements. The pain RT, or the time-delay between occurrence of pain sensation and a subsequent motor response, was measured by making EMG recording on a forearm. The radiant heat stimuli were three, 200, 300, and 350 mcal/sec./cm2, each of which was given through a round radiation window of an algesiometer head. Analysis showed that the pain RTs would be too short to explain higher pain thresholds often found using the time method.

  11. Time-resolved analysis of macromolecular structures during reactions by stopped-flow electrooptics.

    PubMed

    Porschke, D

    1998-07-01

    A stopped-flow field-jump instrument and its use for the analysis of macromolecular structure changes during reactions is described. The operation of the new instrument is simple and reliable, owing to a new type of cell construction with electrodes directly integrated in a quartz cuvette: major advantages are the relatively low demand on sample quantities and a high time resolution. The stopped flow is characterized by a dead time of approximately 0.5 ms. Electric field pulses with field strengths up to 20 kV/cm and rise times in the nanosecond range are applied at adjustable times after stop of the flow. The time resolution of the optical detection is up to the nanosecond time range. The instrument may be used for the combination of stopped flow with temperature-jump and field-jump experiments. A particularly useful new application is the analysis of macromolecular reactions by electrooptical measurements, because electrooptical data provide information about structures. This is demonstrated for the intercalation of ethidium into double-helical DNA. The transients, measured at 313 nm, where the signal is exclusively due to ethidium bound to the DNA, demonstrate a relatively high negative dichroism at 0.5 ms after mixing. The absolute value of this negative dichroism increases in the millisecond time range and approaches the equilibrium value within about a second. The dichroism decay time constants demonstrate a clear increase of the effective DNA length due to ethidium binding, already 0.5 ms after mixing; a further increase to the equilibrium value is found in the millisecond time range. The analysis of these data demonstrate the existence of up to three relaxation processes, depending on the conditions of the experiments. The dichroism amplitudes, together with the decay time constants, indicate that all the reaction states found in the present investigation are complexes with insertion of ethidium residues between basepairs. Moreover, the data clearly show

  12. Bimodal and trimodal multisensory enhancement: effects of stimulus onset and intensity on reaction time.

    PubMed

    Diederich, Adele; Colonius, Hans

    2004-11-01

    Manual reaction times to visual, auditory, and tactile stimuli presented simultaneously, or with a delay, were measured to test for multisensory interaction effects in a simple detection task with redundant signals. Responses to trimodal stimulus combinations were faster than those to bimodal combinations, which in turn were faster than reactions to unimodal stimuli. Response enhancement increased with decreasing auditory and tactile stimulus intensity and was a U-shaped function of stimulus onset asynchrony. Distribution inequality tests indicated that the multisensory interaction effects were larger than predicted by separate activation models, including the difference between bimodal and trimodal response facilitation. The results are discussed with respect to previous findings in a focused attention task and are compared with multisensory integration rules observed in bimodal and trimodal superior colliculus neurons in the cat and monkey.

  13. The simplest chronoscope II: reaction time measured by meterstick versus machine.

    PubMed

    Montare, Alberto

    2010-12-01

    Visual simple reaction time (SRT) scores measured in 31 college students of both sexes by use of the simplest chronoscope methodology (meterstick SRT) were compared to scores obtained by use of an electromechanical multi-choice reaction timer (machine SRT). Four hypotheses were tested. Results indicated that the previous mean value of meterstick SRT was replicated; meterstick SRT was significantly faster than long-standing population estimates of mean SRT; and machine SRT was significantly slower than the same long-standing mean SRT estimates for the population. Also, the mean meterstick SRT of 181 msec. was significantly faster than the mean machine SRT of 294 msec. It was theorized that differential visual information processing occurred such that the dorsal visual stream subserved meterstick SRT; whereas the ventral visual stream subserved machine SRT.

  14. 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.

  15. Time-temperature-transformation curves in chemical reactions regulated by cytoskeletal activity

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Bhaswati; Chaudhuri, Abhishek; Gowrishankar, Kripa; Mayor, Satyajit; Rao, Madan

    2012-02-01

    Efficient and reproducible construction of signaling and sorting complexes, both on the surface and within the living cell, is contingent on local regulation of biochemical reactions by the cellular milieu with active components. We have recently proposed that in many cases this spatiotemporal regulation can be mediated by interaction with components of the dynamic cytoskeleton, where the interplay between active contractility and remodeling of the cytoskeleton results in transient focusing of passive molecules to form clusters, leading to a dramatic increase in the reaction efficiency and output levels. In this presentation, we discuss the implications of actin dynamics by introducing an ``effective temperature,'' which can work as a regulatory parameter for signaling replacing the details of actin dynamics. We show this in time-temperature-transformation plots, with the proposed ``effective temperature'' as a parameter, which paves way for discussion of active chemical thermodynamics.

  16. New Developments in Quantitative Real-time Polymerase Chain Reaction Technology.

    PubMed

    Gadkar, Vija yJ; Filion, Martin

    2014-01-01

    Real time-quantitative PCR (RT-qPCR) technology has revolutionized the detection landscape in every area of molecular biology. The fundamental basis of this technology has remained unchanged since its inception, however various modifications have enhanced the overall performance of this highly versatile technology. These improvements have ranged from changes in the individual components of the enzymatic reaction cocktail (polymerizing enzymes, reaction buffers, probes, etc.) to the detection system itself (instrumentation, software, etc.). The RT-qPCR technology currently available to researchers is more sensitive, faster and affordable than when this technology was first introduced. In this article, we summarize the developments of the last few years in RT-qPCR technology and nucleic acid amplification.

  17. 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

  18. 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

  19. 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.

  20. The reaction time of single motor units in the human muscle.

    PubMed

    Kosarov, D

    1979-01-01

    The reaction time for activating a single motor unit (MU) with one impulse only, upon visual and auditory feed-back was studied in six healthy subjects. Use was made of MUs from m.abductor dig.V. The subjects were trained until they achieved more than 50% correct performances. One hundred responses were investigated in each series of experiments. The stimulus to which the subjects should have to respond was a beam presented on the screen of a "Disa" 14A30 electromyograph. Simultaneously with the beam the stimulator switched on a digital chronometer which was switched off by the MU impulse. Another two series of experiments were also performed in which the subjects responded with a train of impulses from the MU or with a burst of impulses from the whole muscle. It was been found that the mean reaction time for one impulse from one MU is longer (300 ms), for a train of impulses from one MU it is shorter (260 ms) and for a burst of impulses it is the shortest (200 ms). The histogram of distribution in the first series of experiments deviated from the normal distribution and showed a second maximum at 120 ms after the first maximum. The latter did not differ from the maxima in the distributions of the second and third series of experiments--about 200 ms after the visual stimulus presentation. The difference in the mean reaction time for the three series of experiments is due to the differences in the motor tasks connected with different velocity of increase of the muscle tension, as increasing velocity decreases the MU recruitment thresholds. The separate MUs might be activated in the same short periods as the whole muscle but they showed some specificities in the time distribution of the responses which might be due to some discrete mechanisms of the motor control system.

  1. Reliability of the dynavision™ d2 for assessing reaction time performance.

    PubMed

    Wells, Adam J; Hoffman, Jay R; Beyer, Kyle S; Jajtner, Adam R; Gonzalez, Adam M; Townsend, Jeremy R; Mangine, Gerald T; Robinson, Edward H; McCormack, William P; Fragala, Maren S; Stout, Jeffrey R

    2014-01-01

    Recently, the Dynavision™ D2 Visuomotor Training Device (D2) has emerged as a tool in the assessment of reaction time (RT); however, information regarding the reliability of the D2 have been limited, and to date, reliability data have been limited to non- generalizable samples. Therefore, the purpose of this study was to establish intraclass correlation coefficients (ICC2,1) for the D2 that are generalizable across a population of recreationally active young adults. Forty-two recreationally active men and women (age: 23.41 ± 4.84 years; height: 1.72 ± 0.11 m; mass: 76.62 ± 18.26 Kg) completed 6 trials for three RT tasks of increasing complexity. Each trial was separated by at least 48-hours. A repeated measures ANOVA was used to detect differences in performance across the six trials. Intraclass correlation coefficients (ICC2,1) standard error of measurement (SEM), and minimal differences (MD) were used to determine the reliability of the D2 from the two sessions with the least significant difference score. Moderate to strong reliability was demonstrated for visual RT (ICC2,1: 0.84, SEM: 0.033), and reactive ability in both Mode A and Mode B tasks (Mode A hits: ICC2,1: 0.75, SEM: 5.44; Mode B hits: ICC2,1: 0.73, SEM: 8.57). Motor RT (ICC2,1: 0.63, SEM: 0.035s) showed fair reliability, while average RT per hit for Modes A and B showed moderate reliability (ICC2,1: 0.68, SEM: 0.43 s and ICC2,1: 0.72, SEM: 0.03 s respectively). It appears that one familiarization trial is necessary for the choice reaction time (CRT) task while three familiarization trials are necessary for reactive RT tasks. In conclusion, results indicate that the Dynavision™ D2 is a reliable device to assess neuromuscular reactivity given that an adequate practice is provided. The data presented are generalizable to a population of recreationally active young adults. Key PointsThe Dynavision™ D2 is a light-training reaction device, developed to train sensory motor integration through the

  2. 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…

  3. Neuroticism Combined With Slower and More Variable Reaction Time: Synergistic Risk Factors for 7-Year Cognitive Decline in Females

    PubMed Central

    Shickle, Darren A.; Roberts, Beverly A.; Deary, Ian J.

    2012-01-01

    Objective. Among adults, slower and more variable reaction times are associated with worse cognitive function and increased mortality risk. Therefore, it is important to elucidate risk factors for reaction time change over the life course. Method. Data from the Health and Lifestyle Survey (HALS) were used to examine predictors of 7-year decline in reaction time (N = 4,260). Regression-derived factor scores were used to summarize general change across 4 reaction time variables: simple mean, 4-choice mean, simple variability, and 4-choice variability (53.52% of variance). Results. Age (B = .02, p < .001) and HALS1 baseline reaction time (B = −.10, p = .001) were significant risk factors for males (N = 1,899). In addition to these variables, in females (N = 2,361), neuroticism was significant and interacted synergistically with baseline reaction time (B = .06, p = .04). Adjustment for physiological variables explained the interaction with neuroticism, suggesting that candidate mechanisms had been identified. Discussion. A priority for future research is to replicate interactions between personality and reaction time in other samples and find specific mechanisms. Stratification of population data on cognitive health by personality and reaction time could improve strategies for identifying those at greater risk of cognitive decline. PMID:22367712

  4. 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…

  5. 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…

  6. 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.

  7. 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

  8. Serotonin antagonists in the five-choice serial reaction time task and their interactions with nicotine.

    PubMed

    Quarta, Davide; Naylor, Christopher G; Glennon, Jeffrey C; Stolerman, Ian P

    2012-04-01

    Much research has implicated the serotonin (5-HT) system in cognitive functioning and psychomotor stimulant abuse, but its role depends on the subtypes of 5-HT receptors involved and the nature of the behavioural task. Here we aimed to extend previous studies by examining the role of 5-HT1A and 5-HT2C receptors in attentional performance. The effects of the selective 5-HT antagonists WAY-100635 and SB-242084 were assessed alone and for interactions with nicotine in the five-choice serial reaction time task in rats. The effects of several doses of WAY-100635 were tested in combination with a fixed dose of nicotine, and then various doses of nicotine were tested in combination with SB-242084. Systemic administration of WAY-100635 and SB-242084 induced opposing effects on speed-related measures in the five-choice serial reaction time task, with antagonism at 5-HT1A receptors increasing omission errors and response latency, and antagonism at 5-HT2C receptors reducing both omissions and latency, and also increasing anticipatory responses; neither drug affected accuracy. Nicotine itself improved all main indices of attention, and there was preliminary evidence that the detrimental effects of WAY-100635 on response latency were weakened by nicotine. Conversely, treatment with SB-242084 enhanced all speed-related indices of performance to above the levels seen under the influence of nicotine alone, thus suggesting that 5-HT2C antagonists might be useful to decrease reaction times if used as an add-on therapy to treat attentional decline.

  9. Anticipation measures of sequence learning: manual versus oculomotor versions of the serial reaction time task.

    PubMed

    Vakil, Eli; Bloch, Ayala; Cohen, Haggar

    2017-03-01

    The serial reaction time (SRT) task has generated a very large amount of research. Nevertheless the debate continues as to the exact cognitive processes underlying implicit sequence learning. Thus, the first goal of this study is to elucidate the underlying cognitive processes enabling sequence acquisition. We therefore compared reaction time (RT) in sequence learning in a standard manual activated (MA) to that in an ocular activated (OA) version of the task, within a single experimental setting. The second goal is to use eye movement measures to compare anticipation, as an additional indication of sequence learning, between the two versions of the SRT. Performance of the group given the MA version of the task (n = 29) was compared with that of the group given the OA version (n = 30). The results showed that although overall, RT was faster for the OA group, the rate of sequence learning was similar to that of the MA group performing the standard version of the SRT. Because the stimulus-response association is automatic and exists prior to training in the OA task, the decreased reaction time in this version of the task reflects a purer measure of the sequence learning that occurs in the SRT task. The results of this study show that eye tracking anticipation can be measured directly and can serve as a direct measure of sequence learning. Finally, using the OA version of the SRT to study sequence learning presents a significant methodological contribution by making sequence learning studies possible among populations that struggle to perform manual responses.

  10. 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.

  11. Comparison of Analytic Methods for Quantitative Real-Time Polymerase Chain Reaction Data

    PubMed Central

    Chen, Ping

    2015-01-01

    Abstract Polymerase chain reaction (PCR) is a laboratory procedure to amplify and simultaneously quantify targeted DNA molecules, and then detect the product of the reaction at the end of all the amplification cycles. A more modern technique, real-time PCR, also known as quantitative PCR (qPCR), detects the product after each cycle of the progressing reaction by applying a specific fluorescence technique. The quantitative methods currently used to analyze qPCR data result in varying levels of estimation quality. This study compares the accuracy and precision of the estimation achieved by eight different models when applied to the same qPCR dataset. Also, the study evaluates a newly introduced data preprocessing approach, the taking-the-difference approach, and compares it to the currently used approach of subtracting the background fluorescence. The taking-the-difference method subtracts the fluorescence in the former cycle from that in the latter cycle to avoid estimating the background fluorescence. The results obtained from the eight models show that taking-the-difference is a better way to preprocess qPCR data compared to the original approach because of a reduction in the background estimation error. The results also show that weighted models are better than non-weighted models, and that the precision of the estimation achieved by the mixed models is slightly better than that achieved by the linear regression models. PMID:26204477

  12. 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

  13. Comparison of analytic methods for quantitative real-time polymerase chain reaction data.

    PubMed

    Chen, Ping; Huang, Xuelin

    2015-11-01

    Polymerase chain reaction (PCR) is a laboratory procedure to amplify and simultaneously quantify targeted DNA molecules, and then detect the product of the reaction at the end of all the amplification cycles. A more modern technique, real-time PCR, also known as quantitative PCR (qPCR), detects the product after each cycle of the progressing reaction by applying a specific fluorescence technique. The quantitative methods currently used to analyze qPCR data result in varying levels of estimation quality. This study compares the accuracy and precision of the estimation achieved by eight different models when applied to the same qPCR dataset. Also, the study evaluates a newly introduced data preprocessing approach, the taking-the-difference approach, and compares it to the currently used approach of subtracting the background fluorescence. The taking-the-difference method subtracts the fluorescence in the former cycle from that in the latter cycle to avoid estimating the background fluorescence. The results obtained from the eight models show that taking-the-difference is a better way to preprocess qPCR data compared to the original approach because of a reduction in the background estimation error. The results also show that weighted models are better than non-weighted models, and that the precision of the estimation achieved by the mixed models is slightly better than that achieved by the linear regression models.

  14. 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.

  15. 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.

  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. Computational solutions of unified fractional reaction-diffusion equations with composite fractional time derivative

    NASA Astrophysics Data System (ADS)

    Saxena, R. K.; Mathai, A. M.; Haubold, H. J.

    2015-10-01

    This paper deals with the investigation of the computational solutions of an unified fractional reaction-diffusion equation, which is obtained from the standard diffusion equation by replacing the time derivative of first order by the generalized fractional time-derivative defined by Hilfer (2000), the space derivative of second order by the Riesz-Feller fractional derivative and adding the function ϕ (x, t) which is a nonlinear function governing reaction. The solution is derived by the application of the Laplace and Fourier transforms in a compact and closed form in terms of the H-function. The main result obtained in this paper provides an elegant extension of the fundamental solution for the space-time fractional diffusion equation obtained earlier by Mainardi et al. (2001, 2005) and a result very recently given by Tomovski et al. (2011). Computational representation of the fundamental solution is also obtained explicitly. Fractional order moments of the distribution are deduced. At the end, mild extensions of the derived results associated with a finite number of Riesz-Feller space fractional derivatives are also discussed.

  18. Useful field of view in simulated driving: Reaction times and eye movements of drivers

    PubMed Central

    Seya, Yasuhiro; Nakayasu, Hidetoshi; Yagi, Tadasu

    2013-01-01

    To examine the spatial distribution of a useful field of view (UFOV) in driving, reaction times (RTs) and eye movements were measured in simulated driving. In the experiment, a normal or mirror-reversed letter “E” was presented on driving images with different eccentricities and directions from the current gaze position. The results showed significantly slower RTs in the upper and upper left directions than in the other directions. The RTs were significantly slower in the left directions than in the right directions. These results suggest that the UFOV in driving may be asymmetrical among the meridians in the visual field. PMID:24349688

  19. 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)…

  20. On the Long Time Simulation of Reaction-Diffusion Equations with Delay

    PubMed Central

    Zhang, Chengjian

    2014-01-01

    For a consistent numerical method to be practically useful, it is widely accepted that it must preserve the asymptotic stability of the original continuous problem. However, in this study, we show that it may lead to unreliable numerical solutions in long time simulation even if a classical numerical method gives a larger stability region than that of the original continuous problem. Some numerical experiments on the reaction-diffusion equations with delay are presented to confirm our findings. Finally, some open problems on the subject are proposed. PMID:24672296

  1. 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.

  2. Moments of action provide insight into critical times for advection-diffusion-reaction processes

    NASA Astrophysics Data System (ADS)

    Ellery, Adam J.; Simpson, Matthew J.; McCue, Scott W.; Baker, Ruth E.

    2012-09-01

    Berezhkovskii and co-workers introduced the concept of local accumulation time as a finite measure of the time required for the transient solution of a reaction-diffusion equation to effectively reach steady state [Biophys J.BIOJAU0006-349510.1016/j.bpj.2010.07.045 99, L59 (2010); Phys. Rev. EPLEEE81539-375510.1103/PhysRevE.83.051906 83, 051906 (2011)]. Berezhkovskii's approach is a particular application of the concept of mean action time (MAT) that was introduced previously by McNabb [IMA J. Appl. Math.IJAMDM0272-496010.1093/imamat/47.2.193 47, 193 (1991)]. Here, we generalize these previous results by presenting a framework to calculate the MAT, as well as the higher moments, which we call the moments of action. The second moment is the variance of action time, the third moment is related to the skew of action time, and so on. We consider a general transition from some initial condition to an associated steady state for a one-dimensional linear advection-diffusion-reaction partial differential equation (PDE). Our results indicate that it is possible to solve for the moments of action exactly without requiring the transient solution of the PDE. We present specific examples that highlight potential weaknesses of previous studies that have considered the MAT alone without considering higher moments. Finally, we also provide a meaningful interpretation of the moments of action by presenting simulation results from a discrete random-walk model together with some analysis of the particle lifetime distribution. This work shows that the moments of action are identical to the moments of the particle lifetime distribution for certain transitions.

  3. [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.

  4. 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.

  5. 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.

  6. 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

  7. 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.

  8. Development of dispersive XAFS system for analysis of time-resolved spatial distribution of electrode reaction.

    PubMed

    Katayama, Misaki; Miyahara, Ryota; Watanabe, Toshiki; Yamagishi, Hirona; Yamashita, Shohei; Kizaki, Terue; Sugawara, Yoshimi; Inada, Yasuhiro

    2015-09-01

    Apparatus for a technique based on the dispersive optics of X-ray absorption fine structure (XAFS) has been developed at beamline BL-5 of the Synchrotron Radiation Center of Ritsumeikan University. The vertical axis of the cross section of the synchrotron light is used to disperse the X-ray energy using a cylindrical polychromator and the horizontal axis is used for the spatially resolved analysis with a pixel array detector. The vertically dispersive XAFS (VDXAFS) instrument was designed to analyze the dynamic changeover of the inhomogeneous electrode reaction of secondary batteries. The line-shaped X-ray beam is transmitted through the electrode sample, and then the dispersed transmitted X-rays are detected by a two-dimensional detector. An array of XAFS spectra in the linear footprint of the transmitted X-ray on the sample is obtained with the time resolution of the repetition frequency of the detector. Sequential measurements of the space-resolved XAFS data are possible with the VDXAFS instrument. The time and spatial resolutions of the VDXAFS instrument depend on the flux density of the available X-ray beam and the size of the light source, and they were estimated as 1 s and 100 µm, respectively. The electrode reaction of the LiFePO4 lithium ion battery was analyzed during the constant current charging process and during the charging process after potential jumping.

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

    NASA Astrophysics Data System (ADS)

    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.

  10. Reaction time effects in lab- versus Web-based research: Experimental evidence.

    PubMed

    Hilbig, Benjamin E

    2016-12-01

    Although Web-based research is now commonplace, it continues to spur skepticism from reviewers and editors, especially whenever reaction times are of primary interest. Such persistent preconceptions are based on arguments referring to increased variation, the limits of certain software and technologies, and a noteworthy lack of comparisons (between Web and lab) in fully randomized experiments. To provide a critical test, participants were randomly assigned to complete a lexical decision task either (a) in the lab using standard experimental software (E-Prime), (b) in the lab using a browser-based version (written in HTML and JavaScript), or (c) via the Web using the same browser-based version. The classical word frequency effect was typical in size and corresponded to a very large effect in all three conditions. There was no indication that the Web- or browser-based data collection was in any way inferior. In fact, if anything, a larger effect was obtained in the browser-based conditions than in the condition relying on standard experimental software. No differences between Web and lab (within the browser-based conditions) could be observed, thus disconfirming any substantial influence of increased technical or situational variation. In summary, the present experiment contradicts the still common preconception that reaction time effects of only a few hundred milliseconds cannot be detected in Web experiments.

  11. Information Accumulation over Time in Monkey Inferior Temporal Cortex Neurons Explains Pattern Recognition Reaction Time under Visual Noise

    PubMed Central

    Kuboki, Ryosuke; Sugase-Miyamoto, Yasuko; Matsumoto, Narihisa; Richmond, Barry J.; Shidara, Munetaka

    2017-01-01

    We recognize objects even when they are partially degraded by visual noise. We studied the relation between the amount of visual noise (5, 10, 15, 20, or 25%) degrading 8 black-and-white stimuli and stimulus identification in 2 monkeys performing a sequential delayed match-to-sample task. We measured the accuracy and speed with which matching stimuli were identified. The performance decreased slightly (errors increased) as the amount of visual noise increased for both monkeys. The performance remained above 80% correct, even with 25% noise. However, the reaction times markedly increased as the noise increased, indicating that the monkeys took progressively longer to decide what the correct response would be as the amount of visual noise increased, showing that the monkeys trade time to maintain accuracy. Thus, as time unfolds the monkeys act as if they are accumulating the information and/or testing hypotheses about whether the test stimulus is likely to be a match for the sample being held in short-term memory. We recorded responses from 13 single neurons in area TE of the 2 monkeys. We found that stimulus-selective information in the neuronal responses began accumulating when the match stimulus appeared. We found that the greater the amount of noise obscuring the test stimulus, the more slowly stimulus-related information by the 13 neurons accumulated. The noise induced slowing was about the same for both behavior and information. These data are consistent with the hypothesis that area TE neuron population carries information about stimulus identity that accumulates over time in such a manner that it progressively overcomes the signal degradation imposed by adding visual noise. PMID:28127279

  12. Information Accumulation over Time in Monkey Inferior Temporal Cortex Neurons Explains Pattern Recognition Reaction Time under Visual Noise.

    PubMed

    Kuboki, Ryosuke; Sugase-Miyamoto, Yasuko; Matsumoto, Narihisa; Richmond, Barry J; Shidara, Munetaka

    2016-01-01

    We recognize objects even when they are partially degraded by visual noise. We studied the relation between the amount of visual noise (5, 10, 15, 20, or 25%) degrading 8 black-and-white stimuli and stimulus identification in 2 monkeys performing a sequential delayed match-to-sample task. We measured the accuracy and speed with which matching stimuli were identified. The performance decreased slightly (errors increased) as the amount of visual noise increased for both monkeys. The performance remained above 80% correct, even with 25% noise. However, the reaction times markedly increased as the noise increased, indicating that the monkeys took progressively longer to decide what the correct response would be as the amount of visual noise increased, showing that the monkeys trade time to maintain accuracy. Thus, as time unfolds the monkeys act as if they are accumulating the information and/or testing hypotheses about whether the test stimulus is likely to be a match for the sample being held in short-term memory. We recorded responses from 13 single neurons in area TE of the 2 monkeys. We found that stimulus-selective information in the neuronal responses began accumulating when the match stimulus appeared. We found that the greater the amount of noise obscuring the test stimulus, the more slowly stimulus-related information by the 13 neurons accumulated. The noise induced slowing was about the same for both behavior and information. These data are consistent with the hypothesis that area TE neuron population carries information about stimulus identity that accumulates over time in such a manner that it progressively overcomes the signal degradation imposed by adding visual noise.

  13. Fast real-time polymerase chain reaction for quantitative detection of Lactobacillus delbrueckii bacteriophages in milk.

    PubMed

    Martín, Maria Cruz; del Rio, Beatriz; Martínez, Noelia; Magadán, Alfonso H; Alvarez, Miguel A

    2008-12-01

    One of the main microbiological problems of the dairy industry is the susceptibility of starter bacteria to virus infections. Lactobacillus delbrueckii, a component of thermophilic starter cultures used in the manufacture of several fermented dairy products, including yogurt, is also sensitive to bacteriophage attacks. To avoid the problems associated with these viruses, quick and sensitive detection methods are necessary. In the present study, a fast real-time quantitative polymerase chain reaction assay for the direct detection and quantification of L. delbrueckii phages in milk was developed. A set of primers and a TaqMan MGB probe was designed, based on the lysin gene sequence of different L. delbrueckii phages. The results show the proposed method to be a rapid (total processing time 30 min), specific and highly sensitive technique for detecting L. delbrueckii phages in milk.

  14. Indirect Measurement of Sexual Orientation: Comparison of the Implicit Relational Assessment Procedure, Viewing Time, and Choice Reaction Time Tasks.

    PubMed

    Rönspies, Jelena; Schmidt, Alexander F; Melnikova, Anna; Krumova, Rosina; Zolfagari, Asadeh; Banse, Rainer

    2015-07-01

    The present study was conducted to validate an adaptation of the Implicit Relational Assessment Procedure (IRAP) as an indirect latency-based measure of sexual orientation. Furthermore, reliability and criterion validity of the IRAP were compared to two established indirect measures of sexual orientation: a Choice Reaction Time task (CRT) and a Viewing Time (VT) task. A sample of 87 heterosexual and 35 gay men completed all three indirect measures in an online study. The IRAP and the VT predicted sexual orientation nearly perfectly. Both measures also showed a considerable amount of convergent validity. Reliabilities (internal consistencies) reached satisfactory levels. In contrast, the CRT did not tap into sexual orientation in the present study. In sum, the VT measure performed best, with the IRAP showing only slightly lower reliability and criterion validity, whereas the CRT did not yield any evidence of reliability or criterion validity in the present research. The results were discussed in the light of specific task properties of the indirect latency-based measures (task-relevance vs. task-irrelevance).

  15. Age-related slowing of response selection and production in a visual choice reaction time task

    PubMed Central

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

    2015-01-01

    Aging is associated with delayed processing in choice reaction time (CRT) tasks, but the processing stages most impacted by aging have not been clearly identified. Here, we analyzed CRT latencies in a computerized serial visual feature-conjunction task. Participants responded to a target letter (probability 40%) by pressing one mouse button, and responded to distractor letters differing either in color, shape, or both features from the target (probabilities 20% each) by pressing the other mouse button. Stimuli were presented randomly to the left and right visual fields and stimulus onset asynchronies (SOAs) were adaptively reduced following correct responses using a staircase procedure. In Experiment 1, we tested 1466 participants who ranged in age from 18 to 65 years. CRT latencies increased significantly with age (r = 0.47, 2.80 ms/year). Central processing time (CPT), isolated by subtracting simple reaction times (SRT) (obtained in a companion experiment performed on the same day) from CRT latencies, accounted for more than 80% of age-related CRT slowing, with most of the remaining increase in latency due to slowed motor responses. Participants were faster and more accurate when the stimulus location was spatially compatible with the mouse button used for responding, and this effect increased slightly with age. Participants took longer to respond to distractors with target color or shape than to distractors with no target features. However, the additional time needed to discriminate the more target-like distractors did not increase with age. In Experiment 2, we replicated the findings of Experiment 1 in a second population of 178 participants (ages 18–82 years). CRT latencies did not differ significantly in the two experiments, and similar effects of age, distractor similarity, and stimulus-response spatial compatibility were found. The results suggest that the age-related slowing in visual CRT latencies is largely due to delays in response selection and

  16. A solution for measuring accurate reaction time to visual stimuli realized with a programmable microcontroller.

    PubMed

    Ohyanagi, Toshio; Sengoku, Yasuhito

    2010-02-01

    This article presents a new solution for measuring accurate reaction time (SMART) to visual stimuli. The SMART is a USB device realized with a Cypress Programmable System-on-Chip (PSoC) mixed-signal array programmable microcontroller. A brief overview of the hardware and firmware of the PSoC is provided, together with the results of three experiments. In Experiment 1, we investigated the timing accuracy of the SMART in measuring reaction time (RT) under different conditions of operating systems (OSs; Windows XP or Vista) and monitor displays (a CRT or an LCD). The results indicated that the timing error in measuring RT by the SMART was less than 2 msec, on average, under all combinations of OS and display and that the SMART was tolerant to jitter and noise. In Experiment 2, we tested the SMART with 8 participants. The results indicated that there was no significant difference among RTs obtained with the SMART under the different conditions of OS and display. In Experiment 3, we used Microsoft (MS) PowerPoint to present visual stimuli on the display. We found no significant difference in RTs obtained using MS DirectX technology versus using the PowerPoint file with the SMART. We are certain that the SMART is a simple and practical solution for measuring RTs accurately. Although there are some restrictions in using the SMART with RT paradigms, the SMART is capable of providing both researchers and health professionals working in clinical settings with new ways of using RT paradigms in their work.

  17. Effects of Fatigue on Driving Safety: A Comparison of Brake Reaction Times in Night Float and Postcall Physicians in Training

    PubMed Central

    Talusan, Paul G.; Long, Theodore; Halim, Andrea; Guliani, Laura; Carroll, Nicole; Reach, John

    2014-01-01

    Background Concerns about duty hour and resident safety have fostered discussion about postshift fatigue and driving impairment. Objective We assessed how converting to a night float schedule for overnight coverage affected driving safety for trainees. Methods Brake reaction times were measured for internal medicine and orthopaedic surgery resident volunteers after a traditional 28-hour call shift and after a night float shift. We conducted matched paired t tests of preshift and postshift reaction time means. Participants also completed the Epworth Sleepiness Scale pre- and postshift. Results From June to July 2013, we enrolled 58 interns and residents (28 orthopaedic surgery, 30 internal medicine). We included 24 (41%) trainees on night float rotations and 34 (59%) trainees on traditional 28-hour call shifts. For all residents on night float rotations, there was no significant difference pre- and postshift. An increase in reaction times was noted among trainees on 28-hour call rotations. This included no effect on reaction times for internal medicine trainees pre- and postshift, and an increase in reaction times for orthopaedic trainees. For both night float and traditional call groups, there were significant increases in the Epworth Sleepiness Scale. Conclusions Trainees on traditional 28-hour call rotations had significantly worse postshift brake reaction times, whereas trainees on night float rotations had no difference. Orthopaedic trainees had significant differences in brake reaction times after a traditional call shift. PMID:26140113

  18. Human short-term exposure to electromagnetic fields emitted by mobile phones decreases computer-assisted visual reaction time.

    PubMed

    Mortazavi, S M J; Rouintan, M S; Taeb, S; Dehghan, N; Ghaffarpanah, A A; Sadeghi, Z; Ghafouri, F

    2012-06-01

    The worldwide dramatic increase in mobile phone use has generated great concerns about the detrimental effects of microwave radiations emitted by these communication devices. Reaction time plays a critical role in performing tasks necessary to avoid hazards. As far as we know, this study is the first survey that reports decreased reaction time after exposure to electromagnetic fields generated by a high specific absorption rate mobile phone. It is also the first study in which previous history of mobile phone use is taken into account. The aim of this study was to assess both the acute and chronic effects of electromagnetic fields emitted by mobile phones on reaction time in university students. Visual reaction time (VRT) of young university students was recorded with a simple blind computer-assisted-VRT test, before and after a 10 min real/sham exposure to electromagnetic fields of mobile phones. Participants were 160 right-handed university students aged 18-31. To assess the effect of chronic exposures, the reaction time in sham-exposed phases were compared among low level, moderate and frequent users of mobile phones. The mean ± SD reaction time after real exposure and sham exposure were 286.78 ± 31.35 ms and 295.86 ± 32.17 ms (P < 0.001), respectively. The age of students did not significantly alter the reaction time either in talk or in standby mode. The reaction time either in talk or in standby mode was shorter in male students. The students' VRT was significantly affected by exposure to electromagnetic fields emitted by a mobile phone. It can be concluded that these exposures cause decreased reaction time, which may lead to a better response to different hazards. In this light, this phenomenon might decrease the chances of human errors and fatal accidents.

  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. [Relationship between inertial features of the upper extremity and simple reaction time in boys and girls aged 17-18].

    PubMed

    Gutnik, B I; Pankova, N B; Karganov, M Iu; Nash, D

    2014-01-01

    The latent period of visual sensor-motor reaction depends, in part, on the sensory and integrative processes in the brain, but is also influenced by the rate of the muscle contraction. There is no clear evidence in the literature whether the rotational inertia of segments of limbs has any direct effect on the reaction time. The aim of our study was to identify this relationship. The study involved 566 right handed students aged 16-17 of both genders beginning their post puberty period. Reaction time was measured during experimental adduction of the forearm and hand, using a special rotating handle and lever connected to a computer that recorded the reaction time (+/- 1 ms). Calculations of the rotational inertia were carried out using regression models by Zatsiorsky and other authors. Each gender group was divided into three subgroups: with high, medium and low values of rotational inertia. It was found that individuals with high values of rotational inertia of forearm and wrist demonstrated significantly longer reaction times. This pattern was apparent in both gender groups. Although males illustrated greater values of rotational inertia than females they demonstrated relatively shorter reaction times. This contradiction can be explained by greater muscle power of young men. We recommend taking into account the amount of rotational inertia of the responsive segment in all kinds of research which require measurement of reaction time.

  1. Elderly Fallers Enhance Dynamic Stability Through Anticipatory Postural Adjustments during a Choice Stepping Reaction Time

    PubMed Central

    Tisserand, Romain; Robert, Thomas; Chabaud, Pascal; Bonnefoy, Marc; Chèze, Laurence

    2016-01-01

    In the case of disequilibrium, the capacity to step quickly is critical to avoid falling in elderly. This capacity can be simply assessed through the choice stepping reaction time test (CSRT), where elderly fallers (F) take longer to step than elderly non-fallers (NF). However, the reasons why elderly F elongate their stepping time remain unclear. The purpose of this study is to assess the characteristics of anticipated postural adjustments (APA) that elderly F develop in a stepping context and their consequences on the dynamic stability. Forty-four community-dwelling elderly subjects (20 F and 24 NF) performed a CSRT where kinematics and ground reaction forces were collected. Variables were analyzed using two-way repeated measures ANOVAs. Results for F compared to NF showed that stepping time is elongated, due to a longer APA phase. During APA, they seem to use two distinct balance strategies, depending on the axis: in the anteroposterior direction, we measured a smaller backward movement and slower peak velocity of the center of pressure (CoP); in the mediolateral direction, the CoP movement was similar in amplitude and peak velocity between groups but lasted longer. The biomechanical consequence of both strategies was an increased margin of stability (MoS) at foot-off, in the respective direction. By elongating their APA, elderly F use a safer balance strategy that prioritizes dynamic stability conditions instead of the objective of the task. Such a choice in balance strategy probably comes from muscular limitations and/or a higher fear of falling and paradoxically indicates an increased risk of fall. PMID:27965561

  2. A full dimensional time-dependent wave packet study for the H4 four-center, collision induced dissociation, and single exchange reactions: reaction probabilities for J=0.

    PubMed

    Lu, Yunpeng; Lee, Soo-Y; Zhang, Dong H

    2006-01-07

    A time-dependent initial state selected wave packet method has been developed to study the H2(v(1)=10-11,j1=0)+H2'(v2=0,j2=0)-->HH'+HH' four-center (4C) reaction, and two other competing reactions: the H2+H2'-->H+H+H2' collision induced dissociation (CID) and the H2+H2'-->H+HH'+H' single exchange (SE) reaction, in full six dimensions. Initial state-specific total reaction probabilities for these three competing reactions are presented for total angular momentum J=0 and the effects of reagent vibration on reactions are examined. It is found that (a) the CID process is the dominant process over the whole energy range considered in this study, but the 4C and SE processes also have non-negligible probabilities; (b) the SE process has a lower threshold energy than the 4C process, but the SE probability increases slower than the 4C probability as collision energy increases; (c) the vibrational excitation of H2(v1) is much more efficient than translational motion for promoting these processes, in particular to the CID process.

  3. 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.

  4. Transition state geometry of driven chemical reactions on time-dependent double-well potentials.

    PubMed

    Junginger, Andrej; Craven, Galen T; Bartsch, Thomas; Revuelta, F; Borondo, F; Benito, R M; Hernandez, Rigoberto

    2016-11-09

    Reaction rates across time-dependent barriers are difficult to define and difficult to obtain using standard transition state theory approaches because of the complexity of the geometry of the dividing surface separating reactants and products. Using perturbation theory (PT) or Lagrangian descriptors (LDs), we can obtain the transition state trajectory and the associated recrossing-free dividing surface. With the latter, we are able to determine the exact reactant population decay and the corresponding rates to benchmark the PT and LD approaches. Specifically, accurate rates are obtained from a local description regarding only direct barrier crossings and to those obtained from a stability analysis of the transition state trajectory. We find that these benchmarks agree with the PT and LD approaches for obtaining recrossing-free dividing surfaces. This result holds not only for the local dynamics in the vicinity of the barrier top, but also for the global dynamics of particles that are quenched at the reactant or product wells after their sojourn over the barrier region. The double-well structure of the potential allows for long-time dynamics related to collisions with the outside walls that lead to long-time returns in the low-friction regime. This additional global dynamics introduces slow-decay pathways that do not result from the local transition across the recrossing-free dividing surface associated with the transition state trajectory, but can be addressed if that structure is augmented by the population transfer of the long-time returns.

  5. 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.

  6. Electrical Microstimulation of the Pulvinar Biases Saccade Choices and Reaction Times in a Time-Dependent Manner

    PubMed Central

    2017-01-01

    The pulvinar complex is interconnected extensively with brain regions involved in spatial processing and eye movement control. Recent inactivation studies have shown that the dorsal pulvinar (dPul) plays a role in saccade target selection; however, it remains unknown whether it exerts effects on visual processing or at planning/execution stages. We used electrical microstimulation of the dPul while monkeys performed saccade tasks toward instructed and freely chosen targets. Timing of stimulation was varied, starting before, at, or after onset of target(s). Stimulation affected saccade properties and target selection in a time-dependent manner. Stimulation starting before but overlapping with target onset shortened saccadic reaction times (RTs) for ipsiversive (to the stimulation site) target locations, whereas stimulation starting at and after target onset caused systematic delays for both ipsiversive and contraversive locations. Similarly, stimulation starting before the onset of bilateral targets increased ipsiversive target choices, whereas stimulation after target onset increased contraversive choices. Properties of dPul neurons and stimulation effects were consistent with an overall contraversive drive, with varying outcomes contingent upon behavioral demands. RT and choice effects were largely congruent in the visually-guided task, but stimulation during memory-guided saccades, while influencing RTs and errors, did not affect choice behavior. Together, these results show that the dPul plays a primary role in action planning as opposed to visual processing, that it exerts its strongest influence on spatial choices when decision and action are temporally close, and that this choice effect can be dissociated from motor effects on saccade initiation and execution. SIGNIFICANCE STATEMENT Despite a recent surge of interest, the core function of the pulvinar, the largest thalamic complex in primates, remains elusive. This understanding is crucial given the central

  7. A new method for quantitative real-time polymerase chain reaction data analysis.

    PubMed

    Rao, Xiayu; Lai, Dejian; Huang, Xuelin

    2013-09-01

    Quantitative real-time polymerase chain reaction (qPCR) is a sensitive gene quantification method that has been extensively used in biological and biomedical fields. The currently used methods for PCR data analysis, including the threshold cycle method and linear and nonlinear model-fitting methods, all require subtracting background fluorescence. However, the removal of background fluorescence can hardly be accurate and therefore can distort results. We propose a new method, the taking-difference linear regression method, to overcome this limitation. Briefly, for each two consecutive PCR cycles, we subtract the fluorescence in the former cycle from that in the latter cycle, transforming the n cycle raw data into n-1 cycle data. Then, linear regression is applied to the natural logarithm of the transformed data. Finally, PCR amplification efficiencies and the initial DNA molecular numbers are calculated for each reaction. This taking-difference method avoids the error in subtracting an unknown background, and thus it is more accurate and reliable. This method is easy to perform, and this strategy can be extended to all current methods for PCR data analysis.

  8. A multiplex real-time polymerase chain reaction assay to diagnose Epiphyas postvittana (Lepidoptera: Tortricidae).

    PubMed

    Barr, N B; Ledezma, L A; Farris, R E; Epstein, M E; Gilligan, T M

    2011-10-01

    A molecular assay for diagnosis of light brown apple moth, Epiphyas postvittana (Walker) (Lepidoptera: Tortricidae), in North America is reported. The assay multiplexes two TaqMan real-time polymerase chain reaction (RT-PCR) probe systems that are designed to target DNA segments of the internal transcribed spacer region 2 (ITS2) and 18S rRNA gene. The RT-PCR probe designed for the 18S target recognizes a DNA sequence conserved in all of the moths included in the study and functions as a control in the assay. The second probe recognizes a segment of the ITS2 specifically found in E. postvittana and not found in the other moths included in the study, i.e., this segment is not conserved. Inclusion of the two markers in a single multiplex reaction did not affect assay performance. The assay was tested against 637 moths representing > 90 taxa in 15 tribes in all three subfamilies in the Tortricidae. The assay generated no false negatives based on analysis of 355 E. postvittana collected from California, Hawaii, England, New Zealand, and Australia. Analysis of a data set including 282 moths representing 41 genera generated no false positives. Only three inconclusive results were generated from the 637 samples. Spike experiments demonstrated that DNA contamination in the assay can affect samples differently. Contaminated samples analyzed with the ITS2 RT-PCR assay and DNA barcode methodology by using the cytochrome oxidase I gene can generate contradictory diagnoses.

  9. 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.

  10. Effects of intensity and positional predictability of a visual stimulus on simple reaction time.

    PubMed

    Carreiro, Luiz Renato Rodrigues; Haddad, Hamilton; Baldo, Marcus Vinicius Chrysóstomo

    2011-01-10

    The influence of visual stimuli intensity on manual reaction time (RT) was investigated under two different attentional settings: high (Experiment 1) and low (Experiment 2) stimulus location predictability. These two experiments were also run under both binocular and monocular viewing conditions. We observed that RT decreased as stimulus intensity increased. It also decreased as the viewing condition was changed from monocular to binocular as well as the location predictability shifted from low to high. A significant interaction was found between stimulus intensity and viewing condition, but no interaction was observed between neither of these factors and location predictability. These findings support the idea that the stimulus intensity effect arises from purely sensory, pre-attentive mechanisms rather than deriving from more efficient attentional capture.

  11. Rethinking spontaneous giving: Extreme time pressure and ego-depletion favor self-regarding reactions.

    PubMed

    Capraro, Valerio; Cococcioni, Giorgia

    2016-06-02

    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.

  12. Mental chronometry and individual differences: modeling reliabilities and correlations of reaction time means and effect sizes.

    PubMed

    Miller, Jeff; Ulrich, Rolf

    2013-10-01

    We used a general stage-based model of reaction time (RT) to investigate the psychometric properties of mean RTs and experimental effect sizes (i.e., differences in mean RTs). Using the model, formulas were derived for the reliabilities of mean RTs and RT difference scores, and these formulas provide guidance about the number of trials per participant needed to obtain reliable estimates of these measures. In addition, formulas were derived for various different types of correlations computed in RT research (e.g., correlations between a mean RT and an external non-RT measure, between two mean RTs, between a mean RT and an RT effect size). The analysis revealed that observed RT-based correlations depend on many parameters of the underlying processes contributing to RT. We conclude that these correlations often fail to support the inferences drawn from them and that their proper interpretation is far more complex than is generally acknowledged.

  13. Reaction Time Is Slower When Walking at a Slow Pace in Young Adults.

    PubMed

    Lajoie, Yves; Jehu, Deborah A; Richer, Natalie; Tran, Ylan

    2016-01-01

    Limited research has examined attentional requirements of walking at various speeds. Twenty young adults were asked to walk 10 m at their preferred pace, 30% faster or 30% slower while verbally responding "top" as fast as possible to random auditory stimuli. Slow walking demonstrated significantly longer reaction time (RT; 457 ± 91 ms) than preferred (423 ± 80 ms) and fast (396 ± 73 ms) walking speeds, F(2, 38) = 13.4, p < .001; η(2)p = .414. Walking at a preferred pace also led to longer RT than walking at a fast pace (p < .05). Slower RT during slow walking may be attributed to increased task complexity, energy requirements and equilibrium demands. Faster RTs during fast walking could be due to familiarity of the task, higher arousal levels, and similar task instructions compared to slower speeds.

  14. 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

  15. Parameterization of a geometrical reaction time model for two beam nacelle lidars

    NASA Astrophysics Data System (ADS)

    Beuth, Thorsten; Fox, Maik; Stork, Wilhelm

    2015-09-01

    The reaction time model is briefly reintroduced as published in a previous publication to explain the restrictions of detecting a horizontal homogenous wind field by two beams of a LiDAR placed on a wind turbine's nacelle. The model is parameterized to get more general statements for a beneficial system design concept. This approach is based on a parameterization towards the rotor disc radius R. All other parameters, whether they are distances like the measuring length or velocities like the cut-out wind speed, can be expressed by the rotor disc radius R. A review of state-of-the-art commercially available wind turbines and their size and rotor diameter is given to estimate the minimum measuring distances that will benefit most wind turbine systems in present as well as in the near future. In the end, the requirements are matched against commercially available LiDARs to show the necessity to advance such systems.

  16. Experience-dependent effects in unimanual and bimanual reaction time tasks in musicians.

    PubMed

    Hughes, C M; Franz, E A

    2007-01-01

    Engaging in musical training has been shown to result in long-term cognitive benefits. The authors examined whether basic cognitive-motor processes differ in people with extensive musical training and in nonmusicians. Musicians (n = 20) and nonmusicians (n = 20) performed a simple reaction time (RT) task under unimanual and bimanual conditions. Musicians' RTs were faster overall than were those of nonmusicians, and those who began their musical training at an earlier age (around age 7-8 years, on average) exhibited a larger bimanual cost than did those who began later (around 12 years, on average). The authors conclude that experience-dependent changes associated with musical training can result in greater efficacy of interhemispheric connections if those changes occur during certain critical periods of brain development.

  17. Extraversion, threat categorizations, and negative affect: a reaction time approach to avoidance motivation.

    PubMed

    Robinson, Michael D; Meier, Brian P; Vargas, Patrick T

    2005-10-01

    The authors sought to measure a component of the avoidance self-regulation system, specifically one related to object appraisal functions. Participants performed a choice reaction time task (Studies 1 & 2) or a go/no go task (Study 3) in which they were asked to categorize words (e.g., knife) as threatening in nature. In a series of three studies involving 236 undergraduates, the authors found that introverts who were skilled at categorizing events as threatening (vs. introverts slow to do so) experienced more negative affect in their daily lives. Among extraverts, threat categorization performance did not predict negative affect. The authors suggest that implicit threat categorizations render individuals vulnerable to negative affect but that high levels of Extraversion are capable of inhibiting such affective consequences. The authors discuss implications of the findings for extant views of Extraversion, avoidance motivation, and self-regulation.

  18. The quantitative real-time polymerase chain reaction for the analysis of plant gene expression.

    PubMed

    Fitzgerald, Timothy L; McQualter, Richard B

    2014-01-01

    The quantitative real-time polymerase chain reaction is used to simultaneously amplify and quantify a targeted DNA molecule. It can be used to determine exact copy number of a molecule within a sample and/or to compare the quantity of a molecule between samples. When combined with reverse transcription, it is a powerful tool for the analysis of gene expression, and it is widely used for this purpose in plant species. Here we provide an introduction to fundamental concepts relevant for the analysis of gene expression in plants using this technique and a protocol for quantification of the relative expression of a sucrose phosphate synthase gene along the maturation gradient of a sugarcane leaf.

  19. 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

  20. Reaction time as a measure of binocular interaction in human vision.

    PubMed

    Blake, R; Martens, W; Di Gianfilippo, A

    1980-08-01

    In a series of psychophysical experiments monocular and binocular reaction times (RTs) were measured in response to the presentation of sinusoidal grating patterns. Over a wide range of contrast values, binocular RT was consistently faster than monocular RT, even at high-contrast levels where RT had reached asymptotic levels. For observers with good stereopsis this binocular summation effect was greater than that expected on the basis of probability summation alone, whereas observers with deficient stereopsis performed at the level of probability summation. For normal observers broadband random noise presented to one eye produced an elevation in RT to gratings presented to the other eye; no such dichoptic masking effect was found in a stereoblind observer. These results validate the use of RT as an efficient, reliable measure of binocular interaction in human vision.

  1. Reaction times in a bisensory task: implications for attention and speech perception.

    PubMed

    Mynatt, B T

    1977-05-01

    Reading reaction time (RT) to visual stimuli was shown to vary according to the nature of simultaneous auditory stimuli. In Experiment 1, simultaneous different digits produced slower RTs than a burst of speech noise, while identicaly digits produced faster RTs. In Experiments 2 and 3 the stimuli were phoneme pairs which differed on either zero, one, or two articulatory features. Identical phonemes resulted in the fastest RTs. The RTs to non-identical phoneme pairs were not directly related to the number of differing features but were dependent upon the specific feature involved. A two-stage model was proposed to explain the results in which parallel processing of simultaneous input occurs prior to a decision-making stage.

  2. A Serial Reaction Time (SRT) task with symmetrical joystick responding for nonhuman primates.

    PubMed

    Heimbauer, Lisa A; Conway, Christopher M; Christiansen, Morten H; Beran, Michael J; Owren, Michael J

    2012-09-01

    The serial reaction time (SRT) task is a simple procedure in which participants produce differentiated responses to each of a series of stimuli presented at varying locations. Learning about stimulus order is revealed through decreased latencies for structured versus randomized sequences. Although widely used with humans and well suited to nonhumans, this paradigm is little used in comparative research. In the present article, we describe an SRT procedure that uses colored circles as stimuli, a circular layout of locations, and symmetrical joystick deflections as responses. In two experiments, we showed that four rhesus macaques (Macaca mulatta) learned to track sequences up to eight items long, with three animals showing faster responding to repeating sequences than to randomized versions. After extended training, these participants also showed evidence of faster responding at all positions within repeating sequences. This method minimizes response effort, equates effort and travel distance across stimulus locations, and is applicable to any joystick-capable species.

  3. 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.

  4. Neck-shortening effect on prosaccade reaction time formed through saccadic training accompanied by maintenance of neck flexion.

    PubMed

    Kunita, Kenji; Fujiwara, Katsuo

    2009-11-01

    We investigated the effect of neck-shortening on prosaccade reaction time formed through saccadic training accompanied by maintenance of neck flexion. The subjects were 30 university students who exhibited no significant shortening of prosaccade reaction time during maintenance of neck flexion, assigned to three groups: prosaccade training subjects at rest neck position (rest training group); prosaccade training subjects at 20 degrees neck flexion position (neck training group); and untrained subjects (control group). Saccadic training for 1 min was performed ten times per day, and the training period was 14 days. For the control group, no significant postural or training effects on reaction time were found. For both training groups, reaction time at the rest position after training was significantly shorter than that before training. For the neck training group, reaction time after training was significantly shorter at the neck flexion position than at the rest position. Conversely, no significant neck effect was found for the rest training group. This indicates that the shortening effect associated with maintenance of neck flexion on prosaccade reaction time is formed through saccadic training accompanied by maintenance of neck flexion.

  5. 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.

  6. 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.

  7. New buffers to improve the quantitative real-time polymerase chain reaction.

    PubMed

    Ahmad, Ashraf; Ghasemi, Jahan

    2007-08-01

    Real-time PCR is a potent technique for nucleic acid quantification for research and diagnostic purposes, the wide dynamic range being one of the advantages over other techniques like the microarray. Several additives and enhancers have been studied to expand the PCR dynamic range in order to be more efficient in quantifying low quantities of nucleic acids, increase the yield and improve reaction efficiency. Shown here is that a combination of new buffers with the regularly used Tris buffer makes it possible to expand the real-time PCR dynamic range and to improve the efficiency and correlation coefficient. Mixing HEPES, TEA or MOPS with Tris was more efficient than Tris alone. It was also found that, if the pH value of the Tris buffer was calibrated with phosphoric acid instead of hydrochloric acid, then the dynamic range was significantly improved and low quantities could be detected and quantified more efficiently. Mixing more than one compound with the Tris buffer was also effective for expanding the dynamic range and increasing the efficiency and correlation coefficient in quantitative real-time PCR.

  8. Nanostructured biochip for label-free and real-time optical detection of polymerase chain reaction.

    PubMed

    Hiep, Ha Minh; Kerman, Kagan; Endo, Tatsuro; Saito, Masato; Tamiya, Eiichi

    2010-02-19

    In this report, Au-coated nanostructured biochip with functionalized thiolated primers on its surface is developed for label-free and real-time optical detection of polymerase chain reaction (PCR). A PCR chamber of 150 microm in thickness containing Au-coated nanostructured substrate in the bottom layer was bordered with SU-8 100 walls. After immobilization of 5'-thiolated primers on the surface, simultaneous DNA amplification and detection were performed without any labeled molecules via the relative reflected intensity (RRI) of Au-coated nanostructured substrate. When human genomic DNA at several concentrations of 0.2, 0.5 and 1 ng microL(-1) was included in the initial DNA samples, the increases in the RRI peak values were clearly observed with the increasing PCR cycle numbers. We found that the starting point of the optical signal, which was divergent from the background in our PCR biochip, was around 3-4 cycles, much lower than that of the fluorescent real-time PCR analysis (around 23-25 cycles). Our proposed PCR device using Au-coated nanostructured substrate holds noteworthy promise for rapid, label-free and real-time DNA detection for point-of-care testing (POCT) applications.

  9. A Time-Adaptive Integrator Based on Radau Methods for Advection Diffusion Reaction PDEs

    NASA Astrophysics Data System (ADS)

    Gonzalez-Pinto, S.; Perez-Rodriguez, S.

    2009-09-01

    The numerical integration of time-dependent PDEs, especially of Advection Diffusion Reaction type, for two and three spatial variables (in short, 2D and 3D problems) in the MoL framework is considered. The spatial discretization is made by using Finite Differences and the time integration is carried out by means of the L-stable, third order formula known as the two stage Radau IIA method. The main point for the solution of the large dimensional ODEs is not to solve the stage values of the Radau method until convergence (because the convergence is very slow on the stiff components), but only giving a very few iterations and take as advancing solution the latter stage value computed. The iterations are carried out by using the Approximate Matrix Factorization (AMF) coupled to a Newton-type iteration (SNI) as indicated in [5], which turns out in an acceptably cheap iteration, like Alternating Directions Methods (ADI) of Peaceman and Rachford (1955). Some stability results for the whole process (AMF)-(SNI) and a local error estimate for an adaptive time-integration are also given. Numerical results on two standard PDEs are presented and some conclusions about our method and other well-known solvers are drawn.

  10. Cost-effectiveness of one-time genetic testing to minimize lifetime adverse drug reactions.

    PubMed

    Alagoz, O; Durham, D; Kasirajan, K

    2016-04-01

    We evaluated the cost-effectiveness of one-time pharmacogenomic testing for preventing adverse drug reactions (ADRs) over a patient's lifetime. We developed a Markov-based Monte Carlo microsimulation model to represent the ADR events in the lifetime of each patient. The base-case considered a 40-year-old patient. We measured health outcomes in life years (LYs) and quality-adjusted LYs (QALYs) and estimated costs using 2013 US$. In the base-case, one-time genetic testing had an incremental cost-effectiveness ratio (ICER) of $43,165 (95% confidence interval (CI) is ($42,769,$43,561)) per additional LY and $53,680 per additional QALY (95% CI is ($53,182,$54,179)), hence under the base-case one-time genetic testing is cost-effective. The ICER values were most sensitive to the average probability of death due to ADR, reduction in ADR rate due to genetic testing, mean ADR rate and cost of genetic testing.

  11. Multi-capillary-column proton-transfer-reaction time-of-flight mass spectrometry.

    PubMed

    Ruzsanyi, Veronika; Fischer, Lukas; Herbig, Jens; Ager, Clemes; Amann, Anton

    2013-11-05

    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.

  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. Closed-time-path functional formalism in curved spacetime: Application to cosmological back-reaction problems

    NASA Astrophysics Data System (ADS)

    Calzetta, E.; Hu, B. L.

    1987-01-01

    We discuss the generalization to curved spacetime of a path-integral formalism of quantum field theory based on the sum over paths first going forward in time in the presence of one external source from an in vacuum to a state defined on a hypersurface of constant time in the future, and then backwards in time in the presence of a different source to the same in vacuum. This closed-time-path formalism which generalizes the conventional method based on in-out vacuum persistence amplitudes yields real and causal effective actions, field equations, and expectation values. We apply this method to two problems in semiclassical cosmology. First we study the back reaction of particle production in a radiation-filled Bianchi type-I universe with a conformal scalar field. Unlike the in-out formalism which yields complex geometries the real and causal effective action here yields equations for real effective geometries, with more readily interpretable results. It also provides a clear identification of particle production as a dissipative process in semiclassical theories. In the second problem we calculate the vacuum expectation value of the stress-energy tensor for a nonconformal massive λφ4 theory in a Robertson-Walker universe. This study serves to illustrate the use of Feynman diagrams and higher-loop calculations in this formalism. It also demonstrates the economy of this method in the calculation of expectation values over the mode-sum Bogolubov transformation methods ordinarily applied to matrix elements calculated in the conventional in-out approach. The capability of the closed-time-path formalism of dealing with Feynman, causal, and correlation functions on the same footing makes it a potentially powerful and versatile technique for treating nonequilibrium statistical properties of dynamical systems as in early-Universe quantum processes.

  14. Time-dependent insulin oligomer reaction pathway prior to fibril formation: cooling and seeding.

    PubMed

    Sorci, Mirco; Grassucci, Robert A; Hahn, Ingrid; Frank, Joachim; Belfort, Georges

    2009-10-01

    The difficulty in identifying the toxic agents in all amyloid-related diseases is likely due to the complicated kinetics and thermodynamics of the nucleation process and subsequent fibril formation. The slow progression of these diseases suggests that the formation, incorporation, and/or action of toxic agents are possibly rate limiting. Candidate toxic agents include precursors (some at very low concentrations), also called oligomers and protofibrils, and the fibrils. Here, we investigate the kinetic and thermodynamic behavior of human insulin oligomers (imaged by cryo-EM) under fibril-forming conditions (pH 1.6 and 65 degrees C) by probing the reaction pathway to insulin fibril formation using two different types of experiments-cooling and seeding-and confirm the validity of the nucleation model and its effect on fibril growth. The results from both the cooling and seeding studies confirm the existence of a time-changing oligomer reaction process prior to fibril formation that likely involves a rate-limiting nucleation process followed by structural rearrangements of intermediates (into beta-sheet rich entities) to form oligomers that then form fibrils. The latter structural rearrangement step occurs even in the absence of nuclei (i.e., with added heterologous seeds). Nuclei are formed at the fibrillation conditions (pH 1.6 and 65 degrees C) but are also continuously formed during cooling at pH 1.6 and 25 degrees C. Within the time-scale of the experiments, only after increasing the temperature to 65 degrees C are the trapped insulin nuclei and resultant structures able to induce the structural rearrangement step and overcome the energy barrier to form fibrils. This delay in fibrillation and accumulation of nuclei at low temperature (25 degrees C) result in a decrease in the mean length of the fibers when placed at 65 degrees C. Fits of an empirical model to the data provide quantitative measures of the delay in the lag-time during the nucleation process and

  15. Cervine (Cervus elaphus) cytokine mRNA quantification by real-time polymerase chain reaction.

    PubMed

    Harrington, Noel P; Surujballi, Om P; Prescott, John F

    2006-04-01

    It has been difficult to perform cytokine studies for many wildlife and nontraditional species because of a lack of immunologic reagents at the protein level. Recently, simple and rapid assays for quantifying mRNA expression by real-time reverse transcription-polymerase chain reaction (RT-PCR) have been used for analysis of cytokine profiles in humans and other mammalian species. This report describes the development and application of real time RT-PCR to measure the expression of several important elk (Cervus elaphus) cytokine mRNAs, including interleukin (IL)-2, IL-4, IL-10, IL-12p40, interferon-gamma, tumor necrosis factor (TNF)-alpha, and the enzyme-inducible nitric oxide synthase, all of which are involved in immune responses and regulation. For the broadest potential application of the assay, primers and probes were designed using consensus sequences from several species of interest. To obtain standardized quantitative results, external controls consisting of a DNA template for each target gene were used to generate linear standard curves over a 6 to 8 log range with detection of as few as 10 copies of amplicon per reaction. Sample-to-sample variation in the efficiency of the RT, as well as in the quantity and quality of the starting RNA, was compensated for by normalizing the results to the endogenous housekeeping gene beta(2)-microglobulin. The assay was evaluated by monitoring the kinetics of cytokine mRNA synthesis induced by mitogenic and antigenic stimulation of peripheral blood mononuclear cells (PBMCs) from Mycobacterium bovis-infected elk. Concanavalin A-stimulated PBMCs demonstrated a rapid but transient increase in cytokine mRNA expression following in vitro mitogenic activation with optimal mRNA induction observed after 4 to 16 hr. The PBMCs stimulated with the mycobacterial recall antigen, bovine-purified protein derivative (PPD-bovis), demonstrated variable mRNA induction kinetics for each cytokine. Whereas PPD-bovis optimally induced IL-2 m

  16. Time-dependent insulin oligomer reaction pathway prior to fibril formation: Cooling and seeding

    PubMed Central

    Sorci, Mirco; Grassucci, Robert A.; Hahn, Ingrid; Frank, Joachim; Belfort, Georges

    2009-01-01

    The difficulty in identifying the toxic agents in all amyloid-related diseases is likely due to the complicated kinetics and thermodynamics of the nucleation process and subsequent fibril formation. The slow progression of these diseases suggests that the formation, incorporation and/or action of toxic agents is possibly rate limiting. Candidate toxic agents include precursors (some at very low concentrations), also called oligomers and protofibrils, and the fibrils. Here, we investigate the kinetic and thermodynamic behavior of human insulin oligomers (imaged by cryo-EM) under fibril forming conditions (pH 1.6 and 65°C) by probing the reaction pathway to insulin fibril formation using two different types of experiments – cooling and seeding – and confirm the validity of the nucleation model and its effect on fibril growth. The results from both the cooling and seeding studies confirm the existence of a time-changing oligomer reaction process prior to fibril formation that likely involves a rate-limiting nucleation process followed by structural rearrangements of intermediates (into β-sheet rich entities) to form oligomers that then form fibrils. The latter structural rearrangement step occurs even in the absence of nuclei (i.e. with added heterologous seeds). Nuclei are formed at the fibrillation conditions (pH 1.6 and 65°C) but are also continuously formed during cooling at pH 1.6 and 25°C. Within the time-scale of the experiments, only after increasing the temperature to 65°C are the trapped insulin nuclei and resultant structures able to induce the structural rearrangement step and overcome the energy barrier to form fibrils. This delay in fibrillation and accumulation of nuclei at low temperature (25°C), result in a decrease in the mean length of the fibers when placed at 65°C. Fits of an empirical model to the data provide quantitative measures of the delay in the lag-time during the nucleation process and subsequent reduction in fibril growth rate

  17. Switching between hands in a serial reaction time task: a comparison between young and old adults.

    PubMed

    Hoff, Maike; Trapp, Sabrina; Kaminski, Elisabeth; Sehm, Bernhard; Steele, Christopher J; Villringer, Arno; Ragert, Patrick

    2015-01-01

    Healthy aging is associated with a variety of functional and structural brain alterations. These age-related brain alterations have been assumed to negatively impact cognitive and motor performance. Especially important for the execution of everyday activities in older adults (OA) is the ability to perform movements that depend on both hands working together. However, bimanual coordination is typically deteriorated with increasing age. Hence, a deeper understanding of such age-related brain-behavior alterations might offer the opportunity to design future interventional studies in order to delay or even prevent the decline in cognitive and/or motor performance over the lifespan. Here, we examined to what extent the capability to acquire and maintain a novel bimanual motor skill is still preserved in healthy OA as compared to their younger peers (YA). For this purpose, we investigated performance of OA (n = 26) and YA (n = 26) in a bimanual serial reaction time task (B-SRTT), on two experimental sessions, separated by 1 week. We found that even though OA were generally slower in global response times, they showed preserved learning capabilities in the B-SRTT. However, sequence specific learning was more pronounced in YA as compared to OA. Furthermore, we found that switching between hands during B-SRTT learning trials resulted in increased response times (hand switch costs), a phenomenon that was more pronounced in OA. These hand switch costs were reduced in both groups over the time course of learning. More interestingly, there were no group differences in hand switch costs on the second training session. These results provide novel evidence that bimanual motor skill learning is capable of reducing age-related deficits in hand switch costs, a finding that might have important implications to prevent the age-related decline in sensorimotor function.

  18. Production-passage-time approximation: a new approximation method to accelerate the simulation process of enzymatic reactions.

    PubMed

    Kuwahara, Hiroyuki; Myers, Chris J

    2008-09-01

    Given the substantial computational requirements of stochastic simulation, approximation is essential for efficient analysis of any realistic biochemical system. This paper introduces a new approximation method to reduce the computational cost of stochastic simulations of an enzymatic reaction scheme which in biochemical systems often includes rapidly changing fast reactions with enzyme and enzyme-substrate complex molecules present in very small counts. Our new method removes the substrate dissociation reaction by approximating the passage time of the formation of each enzyme-substrate complex molecule which is destined to a production reaction. This approach skips the firings of unimportant yet expensive reaction events, resulting in a substantial acceleration in the stochastic simulations of enzymatic reactions. Additionally, since all the parameters used in our new approach can be derived by the Michaelis-Menten parameters which can actually be measured from experimental data, applications of this approximation can be practical even without having full knowledge of the underlying enzymatic reaction. Here, we apply this new method to various enzymatic reaction systems, resulting in a speedup of orders of magnitude in temporal behavior analysis without any significant loss in accuracy. Furthermore, we show that our new method can perform better than some of the best existing approximation methods for enzymatic reactions in terms of accuracy and efficiency.

  19. Time-resolved luminescence measurements of the magnetic field effect on paramagnetic photosensitizers in photodynamic reactions

    NASA Astrophysics Data System (ADS)

    Mermut, O.; Bouchard, J.-P.; Cormier, J.-F.; Desroches, P.; Diamond, K. R.; Fortin, M.; Gallant, P.; Leclair, S.; Marois, J.-S.; Noiseux, I.; Morin, J.-F.; Patterson, M. S.; Vernon, M.

    2008-02-01

    The development of multimodal molecular probes and photosensitizing agents for use in photodynamic therapy (PDT) is vital for optimizing and monitoring cytotoxic responses. We propose a combinatorial approach utilizing photosensitizing molecules that are both paramagnetic and luminescent with multimodal functionality to perturb, control, and monitor molecular-scale reaction pathways in PDT. To this end, a time-domain single photon counting lifetime apparatus with a 400 nm excitation source has been developed and integrated with a variable low field magnet (0- 350mT). The luminescence lifetime decay function was measured in the presence of a sweeping magnetic field for a custom designed photosensitizing molecule in which photoinduced electron transfer was studied The photosensitizer studied was a donor-acceptor complex synthesized using a porphyrin linked to a fullerene molecule. The magneto-optic properties were investigated for the free-base photosensitizer complex as well as those containing either diamagnetic (paired electron) or paramagnetic (unpaired electron) metal centers, Zn(II) and Cu(II). The magnetic field was employed to affect and modify the spin states of radical pairs of the photosensitizing agents via magnetically induced hyperfine and Zeeman effects. Since the Type 1 reaction pathway of an excited triplet state photosensitizer involves the production of radical species, lifetime measurements were conducted at low dissolved oxygen concentration (0.01ppm) to elucidate the dependence of the magnetic perturbation on the photosensitization mechanistic pathway. To optimize the magnetic response, a solvent study was performed examining the dependence of the emission properties on the magnetic field in solutions of varying dielectric constants. Lastly, the cytotoxicity in murine tumor cell suspensions was investigated for the novel porphyrin-fullerene complex by inducing photodynamic treatments and determining the associated cell survival.

  20. 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

  1. 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.

  2. Effect of total sleep deprivation on reaction time and waking EEG activity in man.

    PubMed

    Lorenzo, I; Ramos, J; Arce, C; Guevara, M A; Corsi-Cabrera, M

    1995-06-01

    Nine paid volunteers were sleep deprived over a period of 40 hours. Every 2 hours during total sleep deprivation (TSD) and after recovery sleep, oral temperature (OT), reaction time (RT) in a vigilance task and electroencephalogram (EEG) with eyes open and closed (C3, C4, T3 and T4) were recorded. Ten artifact-free samples from each condition were Fourier transformed. Absolute power was calculated for six bands. Analyses of variance with deprivation and time of day as factors showed the following significant results: 1) TSD induced an increase in RT, of theta power in all derivations, of beta power in both centrals and a decrease of alpha power with eyes closed; OT was not affected. 2) All bands showed a peak of power at 1800 hours, 2 hours in advance of the OT acrophase at 2000 hours. All variables recovered baseline values after 1 night of sleep. Significant linear correlations of hours of wakefulness with EEG and RT, and of EEG power with OT and RT, were observed. The present findings show a linear increase in EEG power and RT with TSD, and a diurnal oscillation of EEG power, which is independent of TSD.

  3. 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.

  4. 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.

  5. 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.

  6. White and grey matter relations to simple, choice, and cognitive reaction time in spina bifida.

    PubMed

    Dennis, Maureen; Cirino, Paul T; Simic, Nevena; Juranek, Jenifer; Taylor, W Pat; Fletcher, Jack M

    2016-03-01

    Elevated reaction time (RT) is common in brain disorders. We studied three forms of RT in a neurodevelopmental disorder, spina bifida myelomeningocele (SBM), characterized by regional alterations of both white and grey matter, and typically developing individuals aged 8 to 48 years, in order to establish the nature of the lifespan-relations of RT and brain variables. Cognitive accuracy and RT speed and variability were all impaired in SBM relative to the typically developing group, but the most important effects of SBM on RT are seen on tasks that require a cognitive decision rule. Individuals with SBM are impaired not only in speeded performance, but also in the consistency of their performance on tasks that extend over time, which may contribute to poor performance on a range of cognitive tasks. The group with SBM showed smaller corrected corpus callosum proportions, larger corrected cerebellar white matter proportions, and larger corrected proportions for grey matter in the Central Executive and Salience networks. There were clear negative relations between RT measures and corpus callosum, Central Executive, and Default Mode networks in the group with SBM; relations were not observed in typically developing age peers. Statistical mediation analyses indicated that corpus callosum and Central Executive Network were important mediators. While RT is known to rely heavily on white matter under conditions of typical development and in individuals with adult-onset brain injury, we add the new information that additional involvement of grey matter may be important for a key neuropsychological function in a common neurodevelopmental disorder.

  7. 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.

  8. 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.

  9. Rates of vaso-vagal reactions among first time teenaged whole blood, double red cell, and plateletpheresis donors.

    PubMed

    Reiss, Robert F; Harkin, Ruth; Lessig, Marvin; Mascari, Julie

    2009-01-01

    Given the paucity of published data regarding reaction rates in younger teenaged donors, we evaluated the reaction rates in all of our first time teenaged donors after New York Blood Center lowered the minimum permissible age for blood donations from 17 to 16 yr in 2005. The overall rates of vaso-vagal reactions in donors aged 16 to 19, and those resulting in syncope, occurring in 72,769 consecutive first time whole blood, 3,822 double red cell, and 777 platelet apheresis donations were calculated. They were correlated with age and compared to those found in donors aged 20-29. Separate rates were calculated by gender, age in yr, and donation type, and then compared to each other. The overall reaction rate among first time teenaged whole blood donors was 8.2% and was significantly greater than among plateletpheresis donors (4.0%; p <0.0002). The rate in female whole blood donors (10.0%) was significantly higher than in males (6.4%; p <0.0002). In male double red cell donors the overall reaction rate of 3.5% was significantly lower than that found in male whole blood donors (p <0.002). Among both male and female whole blood donors a significant correlation with decreasing donor age between 19 and 16 yr was found (r(2) = 0.981; p = 0.01) and (r(2) = 0.988; p = 0.006), respectively. We conclude that teenaged donors have increased reaction rates when compared to adults and the reaction rates increase with decreasing age. In addition, females have higher reaction rates than males. Finally, reaction rates associated with apheresis donations are significantly lower than those associated with whole blood donations.

  10. 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).

  11. 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.

  12. 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.

  13. 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.

  14. Effect of vestibular stimulation on auditory and visual reaction time in relation to stress

    PubMed Central

    Rajagopalan, Archana; Kumar, Sai Sailesh; Mukkadan, Joseph Kurien

    2017-01-01

    The present study was undertaken to provide scientific evidence and for beneficial effects of vestibular stimulation for the management of stress-induced changes in auditory and visual reaction time (RT). A total of 240 healthy college students of the age group of 18–24 of either gender were a part of this research after obtaining written consent from them. RT for right and left response was measured for two auditory stimuli (low and high pitch) and visual stimuli (red and green) were recorded. A significant decrease in the visual RT for green light and red light was observed and stress-induced changes was effectively prevented followed by vestibular stimulation. Auditory RT for high pitch right and left response was significantly decreased and stress-induced changes was effectively prevented followed by vestibular stimulation. Vestibular stimulation is effective in boosting auditory and visual RT and preventing stress-induced changes in RT in males and females. We recommend incorporation of vestibular stimulation by swinging in our lifestyle for improving cognitive functions. PMID:28217553

  15. Inhibition of Return in Fear of Spiders: Discrepant Eye Movement and Reaction Time Data

    PubMed Central

    Gerdes, Antje B. M.

    2014-01-01

    Inhibition of return (IOR) refers to a bias against returning the attention to a previously attended location. As a foraging facilitator it is thought to facilitate systematic visual search. With respect to neutral stimuli, this is generally thought to be adaptive, but when threatening stimuli appear in our environment, such a bias may be maladaptive. This experiment investigated the influence of phobia-related stimuli on the IOR effect using a discrimination task. A sample of 50 students (25 high, 25 low in spider fear) completed an IOR task including schematic representations of spiders or butterflies as targets. Eye movements were recorded and to assess discrimination among targets, participants indicated with button presses if targets were spiders or butterflies. Reaction time data did not reveal a significant IOR effect but a significant interaction of group and target; spider fearful participants were faster to respond to spider targets than to butterflies. Furthermore, eye-tracking data showed a robust IOR effect independent of stimulus category. These results offer a more comprehensive assessment of the motor and oculomotor factors involved in the IOR effect. PMID:25101171

  16. 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.

  17. 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

  18. 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.

  19. Visual attention in adults with developmental dyslexia: evidence from manual reaction time and saccade latency.

    PubMed

    Judge, Jeannie; Caravolas, Markéta; Knox, Paul C

    2007-05-01

    Two studies were conducted to investigate visual attention deficits in dyslexia. In Experiment 1, adults with dyslexia and age- and IQ-matched controls completed a simple cueing task; participants responded to briefly presented (20 ms) eccentric targets (3 degrees , 6 degrees , or 9 degrees ) with a key press. In Experiment 2, the same participants completed a saccade version of the task, and saccade amplitude, accuracy, and latency were measured. The results revealed comparable performance between the groups on the manual reaction time task. The groups also performed similarly in saccade accuracy and latency. Moreover, neither group showed a visual field asymmetry in their performance, with the exception that adults with dyslexia showed longer saccade latency for 9 degrees targets presented to their left visual field than did controls. However, on the latter measure, the majority (78%) of those with dyslexia performed within the range of the control group. Correlational analyses revealed associations between reading and phoneme awareness in both groups, but phoneme awareness was not associated with visual attention in adult dyslexics. Together, the results are not compatible with a visual attention deficit in adult dyslexia, while they provide support for the phonological deficit hypothesis.

  20. Inter-hemispheric dynamics revealed by reaction time in the Dimond paradigm.

    PubMed

    Leblanc-Sirois, Yanick; Braun, Claude M J

    2015-01-01

    The Dimond paradigm (DP) consists of tachistoscopically presenting two stimuli to be discriminated--either both stimuli in a single visual hemifield or one in each. The DP has recently been implemented using predecessors to index homotopy of the callosal fibre projection with reaction time (RT) as the dependent measure. Using simple perceptual discrimination tasks, it has recently been reported that the advantage of the unilateral stimulation condition significantly decreases with practice. This effect has been interpreted as being due to the plasticity of the callosal network. Two experiments were designed to replicate these two little-known effects, namely callosal homotopy and callosal network plasticity. In addition, new evidence of another type of callosal network plasticity, termed "callosal network dispatching", was sought by introducing double manipulation of orientations of both stimulus-contours and inter-stimulus arrays to the DP. Strong support for the callosal homotopy and callosal network plasticity effects was obtained. In addition, evidence for a "callosal network dispatcher" effect accrued.

  1. Bilinguals reaction times and category goodness judgments in two language-sets: Spanish and English

    NASA Astrophysics Data System (ADS)

    Garcia-Sierra, Adrian

    2005-04-01

    Two monolingual groups (Spanish and English speakers) and one bilingual group (Mexican-American) were compared in reaction times (RTs) and category goodness (CG) ratings during the identification of a synthetic continuum ranging from /ga/ to /ka/. The task consisted of two sessions for the bilingual listeners and one session for the monolingual listeners. Each session was performed in either a Spanish or English language-set. Language-sets were defined by the language used by the researcher and by filler sentences in the language of interest during the identification task (e.g., what do you hear? or Qu fue lo que escuch?). The results show that voicing boundaries were different across all groups including bilinguals in both language-sets (voicing boundary shift). RTs were larger near the voicing boundaries in all groups. Interestingly, bilinguals showed two RT peaks, whereas monolinguals showed only one RT peak. In regard to CG, participants were asked to rate how good exemplar each token was (1=worst; 5=best). Bilinguals rated the synthetic continuum in both language-sets. The scores given by the bilinguals differed in each language-set at VOT values close to the voicing boundary.

  2. Utility of Real-Time Quantitative Polymerase Chain Reaction in Detecting Mycobacterium tuberculosis

    PubMed Central

    Zhang, Mingxin; Zhang, Hui

    2017-01-01

    This study aimed to assess the value of real-time quantitative polymerase chain reaction (RT-qPCR) for the detection of Mycobacterium tuberculosis (MTB). Samples from 192 patients with suspected MTB were examined by RT-qPCR and an improved Löwenstein–Jensen (L-J) culture method. To evaluate the diagnostic usefulness of RT-qPCR in detecting MTB, a receiver operating characteristic (ROC) curve for RT-qPCR was generated, and the area under the curve (AUC) as well as a cutoff value was calculated. Using the L-J culture method as the gold standard, accuracy of the RT-qPCR method for detecting MTB was 92.7%, with sensitivity and specificity of 62.5% and 97.02%, respectively. In comparison with the improved L-J culture method, the AUC of RT-qPCR ROC curve was 0.957, which was statistically significant (p < 0.001). The Youden Index reached the maximum value (0.88) for gene copy number of 794.5 IU/mL, which was used as the cutoff value. RT-qPCR detection of MTB yielded results consistent with those of the improved L-J culture method, with high accuracy. RT-qPCR may be used as an auxiliary method for etiological diagnosis of tuberculosis. PMID:28168192

  3. 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

  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.

  5. 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.

  6. Cost analysis of real-time polymerase chain reaction microbiological diagnosis in patients with septic shock.

    PubMed

    Alvarez, J; Mar, J; Varela-Ledo, E; Garea, M; Matinez-Lamas, L; Rodriguez, J; Regueiro, B

    2012-11-01

    Antibiotic treatment for septic shock is generally prescribed on an empirical basis using broad-spectrum antibiotics. Molecular diagnostic techniques can detect the presence of microbial DNA in blood within a few hours and facilitate early, targeted treatment. The aim of this study was to evaluate the economic impact of a real-time polymerase chain reaction technique, LightCycler SeptiFast (LSC), in patients with sepsis. A cost-minimisation study was carried out in patients admitted with a diagnosis of severe sepsis or septic shock to the intensive care unit of a university hospital. The stay in the intensive care unit, hospital admission, 28-day and six-month mortality, and the economic cost of the clinical process were also evaluated. The study involved 48 patients in the LSC group and 54 patients in the control group. The total cost was €42,198 in the control group versus €32,228 in the LCS group with statistically significant differences (P <0.05), giving rise to an average net saving of €9970 per patient. The mortality rate was similar in both groups. The main finding of this study was the significant economic saving afforded by the use of the LCS technique, due to the shortening of intensive care unit stay and the use of fewer antibiotics.

  7. 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

  8. Fast fingerprinting of arson accelerants by proton transfer reaction time-of-flight mass spectrometry

    NASA Astrophysics Data System (ADS)

    Whyte, Christopher; Wyche, Kevin P.; Kholia, Mitesh; Ellis, Andrew M.; Monks, Paul S.

    2007-06-01

    Current techniques for the forensic analysis of fire debris as a means to detect the presence of arson accelerants normally use off-line sampling with the collection of accelerant vapours on activated charcoal strips and further pre-chemistry prior to analysis. An alternative method for the direct detection of arson accelerants that requires no sample pre-treatment is described here. The analysis uses proton transfer reaction mass spectrometry (PTR-MS), incorporating a time-of-flight mass spectrometer for rapid multichannel compound detection. It is demonstrated that using PTR-MS volatile organic compound (VOC) fingerprints of a given fire accelerant can be collected by simple head space analysis of accelerant burned materials. Using a set of the four most common arson accelerants and four common household building materials, characteristic VOC fingerprints are shown to provide successful identification of the accelerant used to burn each material. There is the potential to develop this methodology for the rapid screening of large numbers of samples.

  9. 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.

  10. Reaction time distribution analysis of neuropsychological performance in an ADHD sample.

    PubMed

    Hervey, Aaron S; Epstein, Jeffery N; Curry, John F; Tonev, Simon; Eugene Arnold, L; Keith Conners, C; Hinshaw, Stephen P; Swanson, James M; Hechtman, Lily

    2006-04-01

    Differences in reaction time (RT) variability have been documented between children with and without Attention Deficit Hyperactivity Disorder (ADHD). Most previous research has utilized estimates of normal distributions to examine variability. Using a nontraditional approach, the present study evaluated RT distributions on the Conners' Continuous Performance Test in children and adolescents from the Multimodal Treatment Study of ADHD sample compared to a matched sample of normal controls (n = 65 pairs). The ex-Gaussian curve was used to model RT and RT variability. Children with ADHD demonstrated faster RT associated with the normal portion of the curve and a greater proportion of abnormally slow responses associated with the exponential portion of the curve. These results contradict previous interpretation that children with ADHD have slower than normal responding and demonstrate why slower RT is found when estimates of variability assume normal Gaussian distributions. Further, results of this study suggest that the greater number of abnormally long RTs of children with ADHD reflect attentional lapses on some but not all trials.

  11. Choice reaction time performance correlates with diffusion anisotropy in white matter pathways supporting visuospatial attention.

    PubMed

    Tuch, David S; Salat, David H; Wisco, Jonathan J; Zaleta, Alexandra K; Hevelone, Nathanael D; Rosas, H Diana

    2005-08-23

    Humans exhibit significant interindividual variability in behavioral reaction time (RT) performance yet the underlying neural mechanisms for this variability remain largely unknown. It has been proposed that interindividual variability in RT performance may be due to differences in white matter (WM) physiological properties, although such a relationship has never been demonstrated in cortical projection or association pathways in healthy young adults. Using diffusion tensor MRI (DTI), we sought to test whether diffusion tensor fractional anisotropy (FA), a measure of the orientational coherence of water self-diffusion, is regionally correlated with RT on a visual self-paced choice RT (CRT) task. CRT was found to be significantly correlated with FA in projection and association pathways supporting visuospatial attention including the right optic radiation, right posterior thalamus, and right medial precuneus WM. Significant correlations were also observed in left superior temporal sulcus WM and the left parietal operculum. The lateralization of the CRT-FA correlation to right visual and parietal WM pathways is consistent with the specialization of right visual and parietal cortices for visuospatial attention. The localization of the CRT-FA correlations to predominantly visual and parietal WM pathways, but not to motor pathways or the corpus callosum indicates that individual differences in visual CRT performance are associated with variations in the WM underlying the visuospatial attention network as opposed to pathways supporting motor movement or interhemispheric transmission.

  12. 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.

  13. 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.

  14. 5-HT4 receptor agonism in the five-choice serial reaction time task.

    PubMed

    Hille, Christopher; Bate, Simon; Davis, John; Gonzalez, Maria I

    2008-12-16

    5-HT4 agonists are currently being developed for the treatment of Alzheimer's disease and have previously been demonstrated to improve cognitive performance in a variety of tests but none that specifically test attention. Here we characterise the 5-HT4 partial agonist SL65.0155 compared to the reference drug, nicotine, in a test that is used to measure attention in rats, the five-choice serial reaction time task (5CSRTT). SL65.0155 (0.1 or 1 mg/kg s.c) and nicotine (0.2 mg/kg s.c.) were tested in protocols using fixed or variable stimulus durations. SL65.0155 improved performance by virtue of reducing incorrect responses and increasing % correct trials. Perseverative responses were reduced by SL65.0155, and latency during incorrect trials was increased following treatment with 0.1 mg/kg SL65.0155. Nicotine, as previously reported, improved performance in several parameters in the 5CSRTT, including response latencies, errors of omission and correct responses in both the baseline and variable stimulus protocol. These data suggest 5-HT4 agonists may have beneficial effects on attention and thereby may be useful for the treatment of cognitive deficits.

  15. Modafinil improves attention, inhibitory control, and reaction time in healthy, middle-aged rats.

    PubMed

    Morgan, Russell E; Crowley, Jaime M; Smith, Roland H; LaRoche, Ronee B; Dopheide, Marsha M

    2007-03-01

    This study examined the effect of the novel psychostimulant modafinil (Provigil) on a variety of cognitive and behavioral measures including associative learning, sustained attention, inhibitory control, and reaction time. Middle-aged female rats (18-20 months old) were administered oral doses of modafinil (0, 8, 32, and 64 mg/kg) and tested in a 3-choice visual discrimination and sustained attention task. Modafinil produced a dose-dependent pattern of improved response accuracy and impulse control (fewer premature responses) and shorter response latencies, without affecting omission errors, motivation or motor control. Although the biochemical mechanism of modafinil is unknown, these results suggest a profile differing from typical psychostimulants (e.g., amphetamine). The implications of these findings for treatment of narcolepsy, ADHD, and various arousal-related disorders are considered. Further research is needed to examine the relative safety, effectiveness, and addictive potential of modafinil, as well as, its effects in comparison with other performance-enhancing drugs (e.g., caffeine, nicotine, and amphetamines).

  16. 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

  17. 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…

  18. 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…

  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. 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 .

  1. 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

  2. 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

  3. Sparse Regression Based Structure Learning of Stochastic Reaction Networks from Single Cell Snapshot Time Series

    PubMed Central

    Ganscha, Stefan; Claassen, Manfred

    2016-01-01

    Stochastic chemical reaction networks constitute a model class to quantitatively describe dynamics and cell-to-cell variability in biological systems. The topology of these networks typically is only partially characterized due to experimental limitations. Current approaches for refining network topology are based on the explicit enumeration of alternative topologies and are therefore restricted to small problem instances with almost complete knowledge. We propose the reactionet lasso, a computational procedure that derives a stepwise sparse regression approach on the basis of the Chemical Master Equation, enabling large-scale structure learning for reaction networks by implicitly accounting for billions of topology variants. We have assessed the structure learning capabilities of the reactionet lasso on synthetic data for the complete TRAIL induced apoptosis signaling cascade comprising 70 reactions. We find that the reactionet lasso is able to efficiently recover the structure of these reaction systems, ab initio, with high sensitivity and specificity. With only < 1% false discoveries, the reactionet lasso is able to recover 45% of all true reactions ab initio among > 6000 possible reactions and over 102000 network topologies. In conjunction with information rich single cell technologies such as single cell RNA sequencing or mass cytometry, the reactionet lasso will enable large-scale structure learning, particularly in areas with partial network structure knowledge, such as cancer biology, and thereby enable the detection of pathological alterations of reaction networks. We provide software to allow for wide applicability of the reactionet lasso. PMID:27923064

  4. 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.

  5. 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

  6. [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

  7. 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.

  8. Measuring time of flight of fusion products in an inertial electrostatic confinement fusion device for spatial profiling of fusion reactions

    SciTech Connect

    Donovan, D. C.; Boris, D. R.; Kulcinski, G. L.; Santarius, J. F.; Piefer, G. R.

    2013-03-15

    A new diagnostic has been developed that uses the time of flight (TOF) of the products from a nuclear fusion reaction to determine the location where the fusion reaction occurred. The TOF diagnostic uses charged particle detectors on opposing sides of the inertial electrostatic confinement (IEC) device that are coupled to high resolution timing electronics to measure the spatial profile of fusion reactions occurring between the two charged particle detectors. This diagnostic was constructed and tested by the University of Wisconsin-Madison Inertial Electrostatic Confinement Fusion Group in the IEC device, HOMER, which accelerates deuterium ions to fusion relevant energies in a high voltage ({approx}100 kV), spherically symmetric, electrostatic potential well [J. F. Santarius, G. L. Kulcinski, R. P. Ashley, D. R. Boris, B. B. Cipiti, S. K. Murali, G. R. Piefer, R. F. Radel, T. E. Radel, and A. L. Wehmeyer, Fusion Sci. Technol. 47, 1238 (2005)]. The TOF diagnostic detects the products of D(d,p)T reactions and determines where along a chord through the device the fusion event occurred. The diagnostic is also capable of using charged particle spectroscopy to determine the Doppler shift imparted to the fusion products by the center of mass energy of the fusion reactants. The TOF diagnostic is thus able to collect spatial profiles of the fusion reaction density along a chord through the device, coupled with the center of mass energy of the reactions occurring at each location. This provides levels of diagnostic detail never before achieved on an IEC device.

  9. 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.

  10. 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.

  11. 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.

  12. 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

  13. 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

  14. Quantitation of transgenic plant DNA in leachate water: real-time polymerase chain reaction analysis.

    PubMed

    Gulden, Robert H; Lerat, Sylvain; Hart, Miranda M; Powell, Jeff R; Trevors, Jack T; Pauls, K Peter; Klironomos, John N; Swanton, Clarence J

    2005-07-27

    Roundup Ready (RR) genetically modified (GM) corn and soybean comprise a large portion of the annual planted acreage of GM crops. Plant growth and subsequent plant decomposition introduce the recombinant DNA (rDNA) into the soil environment, where its fate has not been completely researched. Little is known of the temporal and spatial distribution of plant-derived rDNA in the soil environment and in situ transport of plant DNA by leachate water has not been studied before. The objectives of this study were to determine whether sufficient quantities of plant rDNA were released by roots during growth and early decomposition to be detected in water collected after percolating through a soil profile and to determine the influence of temperature on DNA persistence in the leachate water. Individual plants of RR corn and RR soybean were grown in modified cylinders in a growth room, and the cylinders were flushed with rain water weekly. Immediately after collection, the leachate was subjected to DNA purification followed by rDNA quantification using real-time Polymerase Chain Reaction (PCR) analysis. To test the effects of temperature on plant DNA persistence in leachate water, water samples were spiked with known quantities of RR soybean or RR corn genomic DNA and DNA persistence was examined at 5, 15, and 25 degrees C. Differences in the amounts and temporal distributions of root-derived rDNA were observed between corn and soybean plants. The results suggest that rainfall events may distribute plant DNA throughout the soil and into leachate water. Half-lives of plant DNA in leachate water ranged from 1.2 to 26.7 h, and persistence was greater at colder temperatures (5 and 15 degrees C).

  15. Labile sleep promotes awareness of abstract knowledge in a serial reaction time task.

    PubMed

    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.

  16. 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

  17. 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.

  18. 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.

  19. Vocal reaction times to unilaterally presented concrete and abstract words: towards a theory of differential right hemispheric semantic processing.

    PubMed

    Rastatter, M; Dell, C W; McGuire, R A; Loren, C

    1987-03-01

    Previous studies investigating hemispheric organization for processing concrete and abstract nouns have provided conflicting results. Using manual reaction time tasks some studies have shown that the right hemisphere is capable of analyzing concrete words but not abstract. Others, however, have inferred that the left hemisphere is the sole analyzer of both types of lexicon. The present study tested these issues further by measuring vocal reaction times of normal subjects to unilaterally presented concrete and abstract items. Results were consistent with a model of functional localization which suggests that the minor hemisphere is capable of differentially processing both types of lexicon in the presence of a dominant left hemisphere.

  20. 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

  1. 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.

  2. 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

  3. Estimating diffusivity along a reaction coordinate in the high friction limit: Insights on pulse times in laser-induced nucleation

    NASA Astrophysics Data System (ADS)

    Knott, Brandon C.; Duff, Nathan; Doherty, Michael F.; Peters, Baron

    2009-12-01

    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.

  4. 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.

  5. 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

  6. 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

  7. Detection of Food Hazards in Foods: Comparison of Real Time Polymerase Chain Reaction and Cultural Methods.

    PubMed

    Bonilauri, Paolo; Bardasi, Lia; Leonelli, Roberto; Ramini, Mattia; Luppi, Andrea; Giacometti, Federica; Merialdi, Giuseppe

    2016-01-18

    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. A Reaction Time Experiment on Adult Attachment: The Development of a Measure for Neurophysiological Settings.

    PubMed

    Wichmann, Theresia; Buchheim, Anna; Menning, Hans; Schenk, Ingmar; George, Carol; Pokorny, Dan

    2016-01-01

    In the last few decades, there has been an increase of experimental research on automatic unconscious processes concerning the evaluation of the self and others. Previous research investigated implicit aspects of romantic attachment using self-report measures as explicit instruments for assessing attachment style. There is a lack of experimental procedures feasible for neurobiological settings. We developed a reaction time (RT) experiment using a narrative attachment measure with an implicit nature and were interested to capture automatic processes, when the individuals' attachment system is activated. We aimed to combine attachment methodology with knowledge from implicit measures by using a decision RT paradigm. This should serve as a means to capture implicit aspects of attachment. This experiment evaluated participants' response to prototypic attachment sentences in association with their own attachment classification, measured with the Adult Attachment Projective Picture System (AAP). First the AAP was administered as the standardized interview procedure to 30 healthy participants, which were classified into a secure or insecure group. In the following experimental session, both experimenter and participants were blind with respect to classifications. One hundred twenty eight prototypically secure or insecure sentences related to the eight pictures of the AAP were presented to the participants. Their response and RTs were recorded. Based on the response (accept, reject) a continuous security scale was defined. Both the AAP classification and security scale were related to the RTs. Differentiated study hypotheses were confirmed for insecure sentences, which were accepted faster by participants from the insecure attachment group (or with lower security scale), and rejected faster by participants from secure attachment group (or with higher security scale). The elaborating unconscious processes were more activated by insecure sentences with potential attachment

  9. 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

  10. A Reaction Time Experiment on Adult Attachment: The Development of a Measure for Neurophysiological Settings

    PubMed Central

    Wichmann, Theresia; Buchheim, Anna; Menning, Hans; Schenk, Ingmar; George, Carol; Pokorny, Dan

    2016-01-01

    In the last few decades, there has been an increase of experimental research on automatic unconscious processes concerning the evaluation of the self and others. Previous research investigated implicit aspects of romantic attachment using self-report measures as explicit instruments for assessing attachment style. There is a lack of experimental procedures feasible for neurobiological settings. We developed a reaction time (RT) experiment using a narrative attachment measure with an implicit nature and were interested to capture automatic processes, when the individuals’ attachment system is activated. We aimed to combine attachment methodology with knowledge from implicit measures by using a decision RT paradigm. This should serve as a means to capture implicit aspects of attachment. This experiment evaluated participants’ response to prototypic attachment sentences in association with their own attachment classification, measured with the Adult Attachment Projective Picture System (AAP). First the AAP was administered as the standardized interview procedure to 30 healthy participants, which were classified into a secure or insecure group. In the following experimental session, both experimenter and participants were blind with respect to classifications. One hundred twenty eight prototypically secure or insecure sentences related to the eight pictures of the AAP were presented to the participants. Their response and RTs were recorded. Based on the response (accept, reject) a continuous security scale was defined. Both the AAP classification and security scale were related to the RTs. Differentiated study hypotheses were confirmed for insecure sentences, which were accepted faster by participants from the insecure attachment group (or with lower security scale), and rejected faster by participants from secure attachment group (or with higher security scale). The elaborating unconscious processes were more activated by insecure sentences with potential

  11. 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.

  12. Psy Toolkit: A Novel Web-Based Method for Running Online Questionnaires and Reaction-Time Experiments

    ERIC Educational Resources Information Center

    Stoet, Gijsbert

    2017-01-01

    This article reviews PsyToolkit, a free web-based service designed for setting up, running, and analyzing online questionnaires and reaction-time (RT) experiments. It comes with extensive documentation, videos, lessons, and libraries of free-to-use psychological scales and RT experiments. It provides an elaborate interactive environment to use (or…

  13. 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…

  14. 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…

  15. 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…

  16. 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…

  17. A multiplex real-time polymerase chain reaction assay differentiates between Bolbphorus damnificus and Bolbophorus type II sp

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A duplex quantitative real-time polymerase chain reaction (qPCR) assay was developed to differentiate between Bolbophorus damnificus and Bolbophorus type II species cercariae. Both trematode species are prevalent throughout the commercial catfish industry,.as both infect the ram’s horn snail, Plano...

  18. 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…

  19. 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…

  20. 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…

  1. 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…

  2. [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.

  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-Resolved Spectroscopic Study of the Defluorination and Cyclization Reactions of Lomefloxacin in Water.

    PubMed

    Su, Tao; Li, Ming-De; Ma, Jiani; Phillips, David Lee

    2017-03-23

    The mechanism of the defluorination reaction(s) of lomefloxacin (LF) upon light illumination was investigated by using ultrafast laser flash photolysis combined with transient resonance Raman spectroscopy in near neutral water solution. The zwitterionic configuration of LF was determined to be the main species present in the near neutral water solution and was the species that was photoexcited to initiate the photochemical reaction. Femtosecond transient absorption revealed that the first excited singlet state (S1) of LF did not appreciably undergo intersystem crossing (ISC) and instead partially decayed to the ground state via fluorescence emission and partially underwent the cleavage of the carbon-fluorine bond at position 8 to produce a singlet LF aryl cation intermediate. The transient resonance Raman results provided a direct observation and vibrational spectral characterization of the singlet LF aryl cation species. Subsequently, the transformation from the singlet LF aryl cation to a triplet carbene via an ISC process was seen in nanosecond transient absorption spectra. Finally, the triplet carbene experienced a cyclization reaction with the N-ethyl chain to form a tricyclic product.

  5. Glaucomatous Retinal Nerve Fiber Layer Thickness Loss is associated with Slower Reaction Times under a Divided Attention Task

    PubMed Central

    Tatham, Andrew J.; Boer, Erwin R.; Rosen, Peter N.; Penna, Mauro Della; Meira-Freitas, Daniel; Weinreb, Robert N.; Zangwill, Linda M.; Medeiros, Felipe A.

    2014-01-01

    Purpose To examine the relationship between glaucomatous structural damage and ability to divide attention during simulated driving. Design Cross-sectional observational study. Methods Setting Hamilton Glaucoma Center, University of California San Diego. Patient Population 158 subjects from the Diagnostic Innovations in Glaucoma Study, including 82 with glaucoma and 76 similarly aged controls. Observation Procedure Ability to divide attention was investigated by measuring reaction times to peripheral stimuli (at low, medium or high contrast) while concomitantly performing a central driving task (car following or curve negotiation). All subjects had standard automated perimetry (SAP) and optical coherence tomography was used to measured retinal nerve fiber (RNFL) thickness. Cognitive ability was assessed using the Montreal Cognitive Assessment and subjects completed a driving history questionnaire. Main outcome measures Reaction times to the driving simulator divided attention task. Results The mean reaction times to the low contrast stimulus were 1.05 s and 0.64 s in glaucoma and controls respectively during curve negotiation (P <0.001), and 1.19 s and 0.77 s (P = 0.025) respectively during car following. There was a non-linear relationship between reaction times and RNFL thickness in the better eye. RNFL thickness remained significantly associated with reaction times even after adjusting for age, SAP mean deviation in the better eye, cognitive ability and central driving task performance. Conclusions Although worse SAP sensitivity was associated with worse ability to divide attention, RNFL thickness measurements provided additional information. Information from structural tests may improve our ability to determine which patients are likely to have problems performing daily activities, such as driving. PMID:25068641

  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. The Oxford-Diamond In Situ Cell for studying chemical reactions using time-resolved X-ray diffraction.

    PubMed

    Moorhouse, Saul J; Vranješ, Nenad; Jupe, Andrew; Drakopoulos, Michael; O'Hare, Dermot

    2012-08-01

    A versatile, infrared-heated, chemical reaction cell has been assembled and commissioned for the in situ study of a range of chemical syntheses using time-resolved energy-dispersive X-ray diffraction (EDXRD) on Beamline I12 at the Diamond Light Source. Specialized reactor configurations have been constructed to enable in situ EDXRD investigation of samples under non-ambient conditions. Chemical reactions can be studied using a range of sample vessels such as alumina crucibles, steel hydrothermal autoclaves, and glassy carbon tubes, at temperatures up to 1200 °C.

  8. The Oxford-Diamond In Situ Cell for studying chemical reactions using time-resolved X-ray diffraction

    NASA Astrophysics Data System (ADS)

    Moorhouse, Saul J.; Vranješ, Nenad; Jupe, Andrew; Drakopoulos, Michael; O'Hare, Dermot

    2012-08-01

    A versatile, infrared-heated, chemical reaction cell has been assembled and commissioned for the in situ study of a range of chemical syntheses using time-resolved energy-dispersive X-ray diffraction (EDXRD) on Beamline I12 at the Diamond Light Source. Specialized reactor configurations have been constructed to enable in situ EDXRD investigation of samples under non-ambient conditions. Chemical reactions can be studied using a range of sample vessels such as alumina crucibles, steel hydrothermal autoclaves, and glassy carbon tubes, at temperatures up to 1200 °C.

  9. Plasmon resonance scattering spectroscopy at the single-nanoparticle level: real-time monitoring of a click reaction.

    PubMed

    Shi, Lei; Jing, Chao; Ma, Wei; Li, Da-Wei; Halls, Jonathan E; Marken, Frank; Long, Yi-Tao

    2013-06-03

    A method based on plasmon resonance Rayleigh scattering (PRRS) spectroscopy and dark-field microscopy (DFM) was established for the real-time monitoring of a click reaction at the single-nanoparticle level. Click reactions on the surface of single gold nanoparticles (GNPs) result in interparticle coupling, which leads to a red-shift of the λmax (Δλmax =43 nm) in the PRRS spectra and a color change of the single gold nanoparticles in DFM (from green to orange).

  10. 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 Central

    Sharifdini, Meysam; Mirhendi, Hossein; Ashrafi, Keyhan; Hosseini, Mostafa; Mohebali, Mehdi; Khodadadi, Hossein; Kia, Eshrat Beigom

    2015-01-01

    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. PMID:26350449

  11. 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.

  12. 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.

  13. ANAM4 TBI Reaction Time-Based Tests have Prognostic Utility for Acute Concussion

    DTIC Science & Technology

    2013-07-01

    any confounding effects of practice. This study corroborates find- ings that PRO is sensitive to concussion .’’’^ Both SRT/SR2 and PRO reflect reaction...literature on the cumulative effects of concussion . Prior research showed evidence that 1 or 2 previous concussions do not affect recovery on neuro...Cumulative effects associated with recurrent concussion in collegiate football players; the NCAA Concussion Study. JAMA 2003; 290( 19); 2549-55. 21. Zemper

  14. Accurate time-dependent wave packet study of the Li + H₂⁺ reaction and its isotopic variants.

    PubMed

    Aslan, E; Bulut, N; Castillo, J F; Bañares, L; Roncero, O; Aoiz, F J

    2012-01-12

    The dynamics and kinetics of the Li + H₂⁺ reaction and its isotopic variants (D₂⁺ and T₂⁺) have been studied by using a time-dependent wave packet (TDWP) coupled-channel (CC) method on the ab initio potential energy surface (PES) of Martinazzo et al. [J. Chem. Phys. 2003, 119, 21]. Total initial v = 0, j = 0 state-selected reaction probabilities for the Li + H₂⁺ reaction and its isotopic variants have been calculated from the threshold up to 1 eV for total angular momenta J from 0 to 90. Integral cross sections have been evaluated from the reaction probabilities at collision energies from threshold (≈0.2 eV) up to 1.0 eV collision. The calculated rate constants as a function of temperature show an Arrhenius type behavior in the 200 ≤ T ≤ 1000 K temperature interval. It has been found to be a considerable large intermolecular kinetic isotope effect. The TDWP-CC results are in overall good agreement with those obtained applying the TDWP Centrifugal-Sudden (CS) approximation, showing that the CS approximation is rather accurate for the title reaction.

  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. Use of short-term (5-Minute) and long-term (18-Hour) leaching tests to characterize, fingerprint, and rank mine-waste material from historical mines in the Deer Creek, Snake River, and Clear Creek Watersheds in and around the Montezuma Mining District, Colorado

    USGS Publications Warehouse

    Hageman, Philip L.

    2004-01-01

    Precipitation-induced runoff from historical mine-waste located adjacent to the headwaters of the Snake River, Deer Creek, Saints John Creek, Grizzly Gulch, Stevens Gulch, and Leavenworth Creek contributes to the degradation of water quality in these streams. Because historical mine-waste piles have had long-term exposure to the atmosphere, it is surmised that runoff from these piles, induced by meteorological events such as cloudbursts and snowmelt, may cause mobility of acid and metals into a watershed due to dissolution of soluble minerals. For this study, 13 mine-waste composite samples from various mine-wastes in these drainage basins were leached using both a short-term and a long-term leach test. Analytical results from this combination of leach tests are tools that allow the investigator to quantify (fingerprint) which geochemical components could be expected in runoff from these piles if they were leached by a cloudburst (5-minute leach test), as well as what the ?worst-case? geochemical profile would look like if the material were subject to extended leaching and breakdown of the mine-waste material (18-hour leach test). Also, this combination of leach tests allows the geoscientist the ability to see geochemical changes in the mine-waste leachate over time. That is, does the leachate become more or less acidic over time; does the specific conductance increase or decrease; and are there changes in the concentrations of major or trace elements? Further, use of a ranking scheme described herein will aid in prediction of which historical mine-waste piles have the greatest potential for impact on a watershed should runoff occur. Because of long-term weathering of these historical mine-waste piles, geochemical profiles, leachate time-trends, and relative ranking of the mine-wastes produced from analysis of the leachates are Hageman_SIR_2508.doc 1 7/21/2004 2:50 PM indicative of how the mine-waste piles can be expected to act in the environment and may help to

  17. Metrological characteristics of the flat voltammetric electrode in time domain with a reversible electrochemical reaction running on the surface

    NASA Astrophysics Data System (ADS)

    Suchocki, Krzysztof

    2016-11-01

    The study deals with metrological characteristics of the flat voltammetric electrode used for determination of ions concentration by the DC voltammetric method, where a reversible reaction of electrochemical oxidation/reduction takes place on the surface. The analysis shows that such voltammetric electrode acts as a transducer of the first order, where the input signal is a concentration of marked ions in tested solution and the output signal is the current associated with a reversible reaction of oxidation / reduction. Metrological characteristics of such electrode in the time domain are determined by its sensitivity and time constant. The values of these parameters are defined by measurements of characteristics of the voltammetric electrode, polarization voltage and marked ions. To determine the effect of a particular volume of each of these parameters several numerical simulations are presented.

  18. A new, multiplex, quantitative real-time polymerase chain reaction system for nucleic acid detection and quantification.

    PubMed

    Liang, Fang; Arora, Neetika; Zhang, Kang Liang; Yeh, David Che Cheng; Lai, Richard; Pearson, Darnley; Barnett, Graeme; Whiley, David; Sloots, Theo; Corrie, Simon R; Barnard, Ross T

    2013-01-01

    Quantitative real-time polymerase chain reaction (qPCR) has emerged as a powerful investigative and diagnostic tool with potential to generate accurate and reproducible results. qPCR can be designed to fulfil the four key aspects required for the detection of nucleic acids: simplicity, speed, sensitivity, and specificity. This chapter reports the development of a novel real-time multiplex quantitative PCR technology, dubbed PrimRglo™, with a potential for high-degree multiplexing. It combines the capacity to simultaneously detect many viruses, bacteria, or nucleic acids, in a single reaction tube, with the ability to quantitate viral or bacterial load. The system utilizes oligonucleotide-tagged PCR primers, along with complementary fluorophore-labelled and quencher-labelled oligonucleotides. The analytic sensitivity of PrimRglo technology was compared with the widely used Taqman(®) and SYBR green detection systems.

  19. Real-time ligation chain reaction for DNA quantification and identification on the FO-SPR.

    PubMed

    Knez, Karel; Spasic, Dragana; Delport, Filip; Lammertyn, Jeroen

    2015-05-15

    Different assays have been developed in the past years to meet point-of-care diagnostic tests requirements for fast and sensitive quantification and identification of targets. In this paper, we developed the ligation chain reaction (LCR) assay on the Fiber Optic Surface Plasmon Resonance (FO-SPR) platform, which enabled simultaneous quantification and cycle-to-cycle identification of DNA during amplification. The newly developed assay incorporated FO-SPR DNA melting assay, previously developed by our group. This required establishment of several assay parameters, including buffer ionic strength and thermal ramping speed as these parameters both influence the ligation enzyme performance and the hybridization yield of the gold nanoparticles (Au NPs) on the FO-SPR sensor. Quantification and identification of DNA targets was achieved over a wide concentration range with a calibration curve spanning 7 orders of magnitude and LOD of 13.75 fM. Moreover, the FO-SPR LCR assay could discriminate single nucleotide polymorphism (SNPs) without any post reaction analysis, featuring thus all the essential requirements of POC tests.

  20. Spatiotemporal reaction kinetics of an ultrafast photoreaction pathway visualized by time-resolved liquid x-ray diffraction.

    PubMed

    Kim, Tae Kyu; Lorenc, Maciej; Lee, Jae Hyuk; Lo Russo, Manuela; Kim, Joonghan; Cammarata, Marco; Kong, Qingyu; Noel, Sylvie; Plech, Anton; Wulff, Michael; Ihee, Hyotcherl

    2006-06-20

    We have studied the reaction dynamics for HgI(2) in methanol by using time-resolved x-ray diffraction (TRXD). Although numerous time-resolved spectroscopic studies have provided ample information about the early dynamics of HgI(2), a comprehensive reaction mechanism in the solution phase spanning from picoseconds up to microseconds has been lacking. Here we show that TRXD can provide this information directly and quantitatively. Picosecond optical pulses triggered the dissociation of HgI(2), and 100-ps-long x-ray pulses from a synchrotron probed the evolving structures over a wide temporal range. To theoretically explain the diffracted intensities, the structural signal from the solute, the local structure around the solute, and the hydrodynamics of bulk solvents were considered in the analysis. The results in this work demonstrate that the determination of transient states in solution is strongly correlated with solvent energetics, and TRXD can be used as an ultrafast calorimeter. It also is shown that a manifold of structural channels can be resolved at the same time if the measurements are accurate enough and that global analysis is applied. The rate coefficients for the reactions were obtained by fitting our model against the experimental data in one global fit including all q-values and time delays. The comparison between all putative reaction channels confirms that two-body dissociation is the dominant dissociation pathway. After this primary bond breakage, two parallel channels proceed. Transient HgI associates nongeminately with an iodine atom to form HgI(2), and I(2) is formed by nongeminate association of two iodine atoms.

  1. Similarity solutions of reaction–diffusion equation with space- and time-dependent diffusion and reaction terms

    SciTech Connect

    Ho, C.-L.; Lee, C.-C.

    2016-01-15

    We consider solvability of the generalized reaction–diffusion equation with both space- and time-dependent diffusion and reaction terms by means of the similarity method. By introducing the similarity variable, the reaction–diffusion equation is reduced to an ordinary differential equation. Matching the resulting ordinary differential equation with known exactly solvable equations, one can obtain corresponding exactly solvable reaction–diffusion systems. Several representative examples of exactly solvable reaction–diffusion equations are presented.

  2. Effect of Eight Weekly Aerobic Training Program on Auditory Reaction Time and MaxVO[subscript 2] in Visual Impairments

    ERIC Educational Resources Information Center

    Taskin, Cengiz

    2016-01-01

    The aim of study was to examine the effect of eight weekly aerobic exercises on auditory reaction time and MaxVO[subscript 2] in visual impairments. Forty visual impairment children that have blind 3 classification from the Turkey, experimental group; (age = 15.60 ± 1.10 years; height = 164.15 ± 4.88 cm; weight = 66.60 ± 4.77 kg) for twenty…

  3. Implementation of TTIK method and time of flight for resonance reaction studies at heavy ion accelerator DC-60

    NASA Astrophysics Data System (ADS)

    Nurmukhanbetova, A. K.; Goldberg, V. Z.; Nauruzbayev, D. K.; Rogachev, G. V.; Golovkov, M. S.; Mynbayev, N. A.; Artemov, S.; Karakhodjaev, A.; Kuterbekov, K.; Rakhymzhanov, A.; Berdibek, Zh.; Ivanov, I.; Tikhonov, A.; Zherebchevsky, V. I.; Torilov, S. Yu.; Tribble, R. E.

    2017-03-01

    To study resonance reactions of heavy ions at low energy we have combined the Thick Target Inverse Kinematics Method (TTIK) with Time of Flight method (TF). We used extended target and TF to resolve the identification problems of various possible nuclear processes inherent to the simplest popular version of TTIK. Investigations of the 15N interaction with hydrogen and helium gas targets by using this new approach are presented.

  4. A Flight-Calibrated Methodology for Determination of Cassini Thruster On-Times for Reaction Wheel Biases

    NASA Technical Reports Server (NTRS)

    Sarani, Siamak

    2010-01-01

    This paper describes a methodology for accurate and flight-calibrated determination of the on-times of the Cassini spacecraft Reaction Control System (RCS) thrusters, without any form of dynamic simulation, for the reaction wheel biases. The hydrazine usage and the delta V vector in body frame are also computed from the respective thruster on-times. The Cassini spacecraft, the largest and most complex interplanetary spacecraft ever built, continues to undertake ambitious and unique scientific observations of planet Saturn, Titan, Enceladus, and other moons of Saturn. In order to maintain a stable attitude during the course of its mission, this three-axis stabilized spacecraft uses two different control systems: the RCS and the reaction wheel assembly control system. The RCS is used to execute a commanded spacecraft slew, to maintain three-axis attitude control, control spacecraft's attitude while performing science observations with coarse pointing requirements, e.g. during targeted low-altitude Titan and Enceladus flybys, bias the momentum of reaction wheels, and to perform RCS-based orbit trim maneuvers. The use of RCS often imparts undesired delta V on the spacecraft. The Cassini navigation team requires accurate predictions of the delta V in spacecraft coordinates and inertial frame resulting from slews using RCS thrusters and more importantly from reaction wheel bias events. It is crucial for the Cassini spacecraft attitude control and navigation teams to be able to, quickly but accurately, predict the hydrazine usage and delta V for various reaction wheel bias events without actually having to spend time and resources simulating the event in flight software-based dynamic simulation or hardware-in-the-loop simulation environments. The methodology described in this paper, and the ground software developed thereof, are designed to provide just that. This methodology assumes a priori knowledge of thrust magnitudes and thruster pulse rise and tail-off time

  5. Effect of catalyst concentration and reaction time on the extraction of glucomannan from porang (Amorphophallus oncophyllus) flour via acid hydrolysis

    NASA Astrophysics Data System (ADS)

    Kumoro, A. C.; Yuganta, T. H. A.; Ratnawati, R.; Retnowati, D. S.

    2016-11-01

    High demand of glucomannan for various applications has attracted the attention of researchers to look for efficient extraction method from its botanical sources. The aim of this study is to investigate the effect of catalyst concentration and reaction time on the yield and purity of glucomannan, and profile of reducing sugar during glucomannan extraction from crude porang flour via acid hydrolysis. The effect of catalyst concentration was found to be more pronounced over the effect of reaction time. When catalyst concentration was varied from 0.03125 to 1 M, extraction of glucomannan from porang flour for 1 hour at 60°C yielded 40.5 to 70% glucomannan with purity of 47.35 to 90.18% (w/w). The yield and purity of glucomannan obtained from extraction using catalyst concentration of 1 M for 0.25 to 3 hour ranged between 49 to 66.67% and 58.32 to 90.18% (w/w), respectively. Reduction in glucomannan yield and purity observed at high catalyst concentration and prolong reaction time was likely to be due to over-decomposition. Glucomannan with highest purity (90.18% w/w) was obtained at 66.67% yield from acid hydrolysis of porang flour using 0.5 M hydrochloric acid solution with flour:water ratio of 1:50 at 60°C for 1 hour.

  6. Enhanced fluorescence and structural characteristics of carboxymethyl cellulose/Eu(III) nano-complex: Influence of reaction time.

    PubMed

    Ye, Jun; Wang, Ben; Xiong, Jian; Sun, Runcang

    2016-01-01

    CMC/Eu(III) nano-complexes were synthesized by reacting Eu(3+) with carboxymethyl cellulose (CMC). The SEM and EDS showed that particle size was less than 100nm and evenly distributed. FTIR and XPS indicated that the oxygen atoms in COO (-), OH, and COC were involved in the complexation with Eu(3+), yet, the O atoms were involved in different positions on anhydroglucose rings depending on reaction time. It was found that there were good energy matches between energy levels on ground state of CMC and (5)D0 Eu(III). Moreover, the intensities of (5)D0→(7)F2 of the nano-complexes were stronger than that of (5)D0→(7)F1, which indicated that the Eu(III) was not in the center of symmetry. The optimized reaction time was 35min, at this reaction time the smallest particle size and uniform distribution was obtained, the coordination structure was advantageous for the energy absorption transfer and emission.

  7. Role of reaction time in tuning the morphology and third order nonlinear optical properties of barium borate

    NASA Astrophysics Data System (ADS)

    Sabari Girisun, T. C.; Saravanan, M.; Vinitha, G.

    2017-03-01

    Single crystalline nanoclusters and nanorods like structure of barium borate (β- BaB2O4) were synthesized by organic free hydrothermal method at various reaction times of 8, 24 and 48 h. XRD shows the formation of pure and single phase of β- BaB2O4 with improved crystallinity at elevated reaction time. β- BaB2O4 crystallizes in hexagonal system with lattice parameter a=b=12.53 Å and c=12.72 Å. The surface morphology picturizes the formation of nanoclusters and rod structures with several micrometer length and nanometer diameter. By increasing the reaction time and due to prolonged pressure, aggregation followed by elongation resulted in the transformation of nanoclusters into rod like structure. The nanostructured barium borates possess strong UV absorbance and wide optical window. The nonlinear optical studies by Z- scan technique shows the material to possess saturable absorption and self-defocusing nature. A strong variation in third order nonlinear optical parameters with change in the morphology of β- BaB2O4 was observed. Also β- BaB2O4 rod like structure is identified to be more efficient optical limiters in the green regime of continuous wave lasers.

  8. EEG amplitude spectra before near threshold visual presentations differentially predict detection/omission and short-long reaction time outcomes.

    PubMed

    Achim, André; Bouchard, Julie; Braun, Claude M J

    2013-07-01

    Performance in simple stimulus detection manifests as both probability of detection and speed of signaling detected stimuli. These two dimensions of performance across trials were examined with respect to brain states just prior to stimulus delivery, using near threshold stimuli targeting the magnocellular or the parvocellular visual streams in an attempt to isolate differential perceptual preparation. The EEG amplitude of 12 university students was analyzed in spectral bands from 2 to 50 Hz at 9 bilateral channel pairs in a window covering -450 ms to +50 ms relative to stimulus onset. A hierarchical statistical procedure was applied to control false positive results. EEG power in the 2, 4, 8 and 10 Hz bands was found significantly lower at the F7-F8 channel pair both before detected compared to omitted stimuli and before the fastest compared to slowest reaction time quartiles, with no stimulus type effect. In addition, the 22 and 24 Hz band activity was lower prior to better performance frontally (F3-F4, F7-F8) in reaction time but not in detection, while it was larger centro-parietally (CP1-CP2, P3-P4) in detection but not in reaction times. Spectral analysis thus shows stimulus detection and response speed to depend partly on common and partly on distinct pre-stimulus brain states.

  9. Effect of Various Eye Exercise Techniques along with Pranayama on Visual Reaction Time: A Case Control Study

    PubMed Central

    Gosewade, Nitin B.; Shende, Vinod S.; Kashalikar, Shriniwas J.

    2013-01-01

    Introduction: We depend on eyesight more than any other of our senses to maneuver through the space around us. In a fraction of a second, our eyes work with our brain to tell us the size, shape, colour, and texture of an object. Our eyes are body’s most highly developed sensory organs. The use of computers and television in the era of information technology has given new heights to the professional success rate and it saves time but on the other hand, it has led to an increase in the number of patients with ocular complaints. Aims: The objective of the study was to study the effect of eye exercise techniques along with kapalbhati pranayama on Visual Reaction Time (VRT). Material & Methods: Total 60 subjects in an age group of 18–30 were recruited in the study. All the subjects were divided into two equal groups (study group and control group) containing 30 subjects (18 male & 12 female) each. Both the male and female subjects were selected on the basis of their voluntary involvement. Visual reaction time for red and green light was recorded from all 60 subjects before the start of the study. Study group subjects were trained to practice various eye exercise techniques and kapalbhati pranayama for 8 weeks regularly whereas control group were busy with their routine activities. After 8 weeks, visual reaction time was measured for red and green light from all 60 subjects. Statistical Analysis: Data expressed as Mean ± S.D, Student t –test was applied for analysis of data, p value <0.05 is taken as statistically significant. Results: Statistical analysis of data shows that there is a significant decrease in the visual reaction time for red and green light after intervention in study group (p value <0.05). Whereas there is no significant decrease in VRT in control group (p value >0.05). Conclusion: The results of our study suggest that simple eye exercises along with pranayama helps in improvement of visual reaction time. PMID:24179885

  10. [Evaluation of short-time premedication with d-chlorpheniramine maleate injection for paclitaxel-induced hypersensitivity reaction].

    PubMed

    Harada, Tomohiko; Doi, Masakazu; Yamada, Yasuhiko; Akase, Tomohide

    2008-08-01

    Paclitaxel(referred to hereinafter as PTX )is used in ovarian cancer, non-small cell lung cancer, breast cancer, gastric cancer, and endometrial cancer with positive treatment result reports. However, severe allergic reactions such as decreases in blood pressure and impaired breathing occur with relatively high frequency. For the prevention of such allergic reactions, administration of a premedication composed of the three components, dexamethasone sodium phosphate injection, diphenhydramine hydrochloride tablet, and ranitidine hydrochloride injection solution(or injectable famodine), is advised in the appended documentation. Administration is difficult because, among these three components, only diphenhydramine hydrochloride is administered orally and thus must be provided through the internal medicine department. Particularly when this combined dosage is administered as outpatient chemotherapy, the doctor must prescribe diphenhydramine hydrochloride tablets, and the patient must not forget to bring them on the day in which chemotherapy is administered. Also, checks by the medical staff such as pharmacists and nurses are required, complicating the administration of this therapy further. Taking this situation into consideration, our hospital uses a short-time premedication method wherein d-Chlorpheniramine Maleate injections are substituted for diphenhydramine hydrochloride tablets, and the time required for premedication is reduced to 15 minutes. This study investigated the allergic reaction ratio to consider the safety and usefulness of the short-time premedication method used at our hospital. The chemotherapy regimens conducted for the subject patients were 9 cases of PTX+CBDCA, 6 cases of biweekly- PTX, and 5 cases of weekly-PTX. A total of 67 PTX injections were given, 15 of them being first-time administrations. The ratio of allergic/hypersensitivity reactions was 10.0%(2 cases in 20). The short-time premedication method using d-Chlorpheniramine Maleate

  11. Real-Time Polymerase Chain Reaction Detection of Angiostrongylus cantonensis DNA in Cerebrospinal Fluid from Patients with Eosinophilic Meningitis.

    PubMed

    Qvarnstrom, Yvonne; Xayavong, Maniphet; da Silva, Ana Cristina Aramburu; Park, Sarah Y; Whelen, A Christian; Calimlim, Precilia S; Sciulli, Rebecca H; Honda, Stacey A A; Higa, Karen; Kitsutani, Paul; Chea, Nora; Heng, Seng; Johnson, Stuart; Graeff-Teixeira, Carlos; Fox, LeAnne M; da Silva, Alexandre J

    2016-01-01

    Angiostrongylus cantonensis is the most common infectious cause of eosinophilic meningitis. Timely diagnosis of these infections is difficult, partly because reliable laboratory diagnostic methods are unavailable. The aim of this study was to evaluate the usefulness of a real-time polymerase chain reaction (PCR) assay for the detection of A. cantonensis DNA in human cerebrospinal fluid (CSF) specimens. A total of 49 CSF specimens from 33 patients with eosinophilic meningitis were included: A. cantonensis DNA was detected in 32 CSF specimens, from 22 patients. Four patients had intermittently positive and negative real-time PCR results on subsequent samples, indicating that the level of A. cantonensis DNA present in CSF may fluctuate during the course of the illness. Immunodiagnosis and/or supplemental PCR testing supported the real-time PCR findings for 30 patients. On the basis of these observations, this real-time PCR assay can be useful to detect A. cantonensis in the CSF from patients with eosinophilic meningitis.

  12. Rapid detection of sacbrood virus in honeybee using ultra-rapid real-time polymerase chain reaction.

    PubMed

    Yoo, Mi-Sun; Thi, Kim Cuc Nguyen; Van Nguyen, Phu; Han, Sang-Hoon; Kwon, Soon-Hwan; Yoon, Byoung-Su

    2012-01-01

    A real-time reverse transcription-polymerase chain reaction (qRT-PCR) assay was developed for the fast and highly sensitive detection of the sacbrood virus (SBV) genome and applied to honeybee samples. Using plasmid DNA containing a partial SBV genome and diluted serially, as few as 1×10(2)copies/μl (correlation co-efficiency >0.99) were detected by the qRT-PCR assay, whereas 1×10(3)copies/μl were detected by the conventional RT-PCR assay. As a rapid detection method, ultra-rapid real-time PCR (URRT-PCR) was carried out with a GenSpector TMC-1000 silicon-glass chip-based thermal cycler, which has a 6μl micro-chamber volume and a fast outstandingly heating/cooling rate. Using this method, 10(3)copies of pBX-SBV3.8 clone were detected within 17 min after 40 PCR cycles, including melting point analysis. To reduce the detection time for SBV, synthesis of the cDNA of the SBV genome from a honeybee sample was attempted for different reaction times and the cDNA was used as the template for URRT-PCR assays. The results indicated that a 5 min reaction time was sufficient to synthesize cDNA as the template for the SBV URRT-PCR assay. This study described a novel PCR-based method that is able to detect an RNA virus in environmental samples within 22 min, including reverse transcription, PCR detection and melting point analysis in real-time.

  13. Combining direct residence time measurements and biogeochemistry to calculate in-situ reaction rates in the hyporheic zone

    NASA Astrophysics Data System (ADS)

    Pittroff, Marco; Gilfedder, Benjamin

    2015-04-01

    The hyporheic zone is an active interface between groundwater, riparian and surface water systems. Exchange and reaction of water, nutrients, and organic matter occur due to variations in surface and groundwater flow regimes, bed topography and active biogeochemistry fuelled by bioavailable carbon. There has been an increasing focus on coupling the residence time of surface water in the hyporheic zone with biogeochemical reactions. However, there are very few tracers that can be used to measure residence times in-situ, especially in complex groundwater-surface water settings. In this work we have used the natural radioisotope Radon (222Rn) as an in-situ tracer for river water residence time in a riffle-pool sequence (Rote Main River), and combined this information with biogeochemical parameters (DOC and C quality, O3, NO3, CO2). We can clearly observe a dependence of reaction progress on the water residence times, with oxygen and nitrate reduction following inverse logarithmic trends as a function of time. By comparing with initial concentrations (the river end member) with riverbed levels we have estimated first-order in-situ reduction rates for nitrate and oxygen. Nitrate reduction rates are at the higher end of published values, which is likely due to the continual supply of bioavailable carbon from the river system. This work helps to better understand the function and efficiency of the hyporheic zone as a natural filter for redox sensitive species such as nitrate at the groundwater - steam interface. It also provides a useful method for estimating residence times in complex, higher order river systems.

  14. Reactivity of TEMPO toward 16- and 17-electron organometallic reaction intermediates: a time-resolved IR study.

    PubMed

    Lomont, Justin P; Nguyen, Son C; Harris, Charles B

    2013-07-31

    The (2,2,6,6-tetramethylpiperidin-1-yl)oxyl radical (TEMPO) has been employed for an extensive range of chemical applications, ranging from organometallic catalysis to serving as a structural probe in biological systems. As a ligand in an organometallic complex, TEMPO can exhibit several distinct coordination modes. Here we use ultrafast time-resolved infrared spectroscopy to study the reactivity of TEMPO toward coordinatively unsaturated 16- and 17-electron organometallic reaction intermediates. TEMPO coordinates to the metal centers of the 16-electron species CpCo(CO) and Fe(CO)4, and to the 17-electron species CpFe(CO)2 and Mn(CO)5, via an associative mechanism with concomitant oxidation of the metal center. In these adducts, TEMPO thus behaves as an anionic ligand, characterized by a pyramidal geometry about the nitrogen center. Density functional theory calculations are used to facilitate interpretation of the spectra and to further explore the structures of the TEMPO adducts. To our knowledge, this study represents the first direct characterization of the mechanism of the reaction of TEMPO with coordinatively unsaturated organometallic complexes, providing valuable insight into its reactions with commonly encountered reaction intermediates. The similar reactivity of TEMPO toward each of the species studied suggests that these results can be considered representative of TEMPO's reactivity toward all low-valent transition metal complexes.

  15. Time-resolved and steady-state fluorescence studies of excited-state proton-transfer reactions of proflavine

    NASA Astrophysics Data System (ADS)

    De Silvestri, S.; Laporta, P.

    1984-01-01

    Time-resolved and steady-state fluorescence studies of proflavine in aqueous solution are presented. The observation of a monoexponential fluorescence decay with a time constant decreasing with increasing pH and the presence of an anomalous red-shift in the fluorescence spectrum as a function of pH indicate the existence of a complex proton-transfer mechanism in the excited state. A reaction scheme is proposed and the corresponding proton-transfer rates are evaluated. An excited-state pK value of 12.85 is obtained for the equilibrium between the cationic form of proflavine and the same form dissociated at an amino group.

  16. Rapid and inexpensive species differentiation using a multiplex real-time polymerase chain reaction high-resolution melt assay.

    PubMed

    Elkins, Kelly M; Perez, Anjelica C U; Sweetin, Katherine C

    2016-05-01

    We demonstrate a method for developing real-time polymerase chain reaction (PCR) high-resolution melt (HRM) assays to identify multiple species present in a mixture simultaneously using LCGreen Plus and melt temperatures. Highly specific PCR primers are designed to yield amplicons with different melt temperatures for simple routine species identification compared with differentiating melt curve kinetics traces or difference plots. This method is robust and automatable, and it leads to savings in time and reagent costs, is easily modified to probe any species of interest, eliminates the need for post-PCR gel or capillary electrophoresis in routine assays, and requires no expensive dye-labeled primers.

  17. The Effect of Time of Day on the Reaction to Stress. Final Report.

    ERIC Educational Resources Information Center

    Osborne, Francis H.

    This study obtains evidence for the effect of time of day on learning in a stressful situation. A series of five experiments were performed to assess the effects of this variable on learning using albino rat subjects. None of the experiments provide overwhelming evidence for the effect of time of day when taken alone and each leaves questions…

  18. Does Occupational Exposure of Shahid Dastghieb International Airport Workers to Radiofrequency Radiation Affect Their Short Term Memory and Reaction Time?

    PubMed Central

    Jarideh, S.; Taeb, S.; Pishva, S. M.; Haghani, M.; Sina, S.; Mortazavi, S. A. R.; Hosseini, M. A.; Nematollahi, S.; Shokrpour, N.; Hassan Shahi, M.; Mortazavi, S. M. J.

    2015-01-01

    Background Airport workers are continuously exposed to different levels of radiofrequency microwave (RF/MW) radiation emitted by radar equipments. Radars are extensively used in military and aviation industries. Over the past several years, our lab has focused on the health effects of exposure to different sources of electromagnetic fields such as cellular phones, mobile base stations, mobile phone jammers, laptop computers, radars, dentistry cavitrons and MRI. The main goal of this study was to investigate if occupational exposure of Shahid Dastghieb international airport workers to radiofrequency radiation affects their short term memory and reaction time. Methods Thirty two airport workers involved in duties at control and approach tower (21 males and 11 females), with the age range of 27-67 years old (mean age of 37.38), participated voluntary in this study. On the other hand, 29 workers (13 males, and 16 females) whose offices were in the city with no exposure history to radar systems were also participated in this study as the control group. The employees’ reaction time and short term memory were analyzed using a standard visual reaction time (VRT) test software and the modified Wechsler memory scale test, respectively. Results The mean± SD values for the reaction times of the airport employees (N=32) and the control group (N=29) were 0.45±0.12 sec and 0.46±0.17 sec, respectively.  Moreover, in the four subset tests; i.e. paired words, forward digit span, backward digit span and word recognition, the following points were obtained for the airport employees and the control group, respectively: (i) pair words test: 28.00±13.13 and 32.07±11.65, (ii) forward digit span: 8.38±1.40 and 9.03±1.32, (iii) backward digit span: 5.54±1.87 and 6.31±1.46, and (iv) word recognition: 5.73±2.36 and 6.50±1.93. These differences were not statistically significant. Conclusion The occupational exposure of the employees to the RF radiation in Shahid Dastghieb

  19. Indirect antiglobulin test-crossmatch using low-ionic-strength saline-albumin enhancement medium and reduced incubation time: effectiveness in the detection of most clinically significant antibodies and impact on blood utilization.

    PubMed

    Dinardo, C L; Bonifácio, S L; Mendrone, A

    2014-01-01

    Indirect antiglobulin test-crossmatch (IAT-XM) using enhancement media such as low-ionic-strength saline (LISS) and polyethylene glycol (PEG) usually requires 15 minutes of incubation. These methods are necessary when testing samples from blood recipients who have a higher risk of alloimmunization. In emergency situations, IAT-XM can be time-consuming and can influence presurgery routine, resulting in more red blood cell (RBC) units being tested and stored to avoid the transfusion of uncrossmatched ones. The objective of this study was to evaluate the performance of a LISS-albumin enhancer to intensify antigen-antibody reaction after 5 minutes of 37oC incubation and compare this performance with that of other enhancers, gel, and conventional tube testing. Second, the study evaluated the impact of this method's implementation in the C:T ratio (crossmatched to transfused RBC units) of a transfusion laboratory. Ninety serum samples containing alloantibodies of potential clinical significance were tested against phenotyped RBCs using four different methods: (1) tube with LISS-albumin enhancer (5 minutes of incubation), (2) tube with LISS-albumin and PEG (15 minutes of incubation), (3) gel, and (4) conventional tube method (60 minutes of incubation). In parallel, the study compared the C:T ratio of a tertiary-hospital transfusion laboratory in two different periods: 3 months before and 3 months after the implementation of the 5-minute IAT-XM protocol. The use of LISS-albumin with 5 minutes of incubation exhibited the same performance as LISS-albumin, PEG, and gel with 15 minutes of incubation. Conventional tube method results were equally comparable, but reactions were significantly less intense, except for anti-c (p = 0.406). Accuracy was 100 percent for all selected methods. After the implementation of the 5-minute IAT-XM protocol, the C:T ratio fell from 2.74 to 1.29 (p < 0.001). IAT-XM can have its incubation time reduced to 5 minutes with the use of LISS

  20. Alteration of the Martian Surface Through Time: A Reaction Path Modeling Approach

    NASA Astrophysics Data System (ADS)

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

    1995-09-01

    We have performed preliminary geochemical reaction path calculations [1] that attempt to model reasonable martian geologic processes under various climatic conditions postulated for Mars during its planetary evolution [2]. Weathering and fluid evaporation and freezing are discussed here. Under current Earth conditions, 25 degrees C rainwater in equilibrium with the atmosphere has a calculated pH=5.66, dissolved O2=2.5x10^-4 mole/kg, and dissolved CO2=1.3x10^-5 mole/kg. In contrast, martian rainwater in a postulated early, warm and wet climate would have lower pH,, higher dissolved CO2, and lower dissolved oxygen. For instance, in a martian atmosphere with pCO2=2.2 bar [3] and pO2=10^-5 bar, rainwater is calculated to have pH=3.96, dissolved CO2 of 7.5x10^-2 mole/kg, and dissolved O2=1.3x10^-8 mole/kg. If, under these climatic conditions, there was also extensive basaltic volcanism, then rainwater would be further modified chemically by solution of volcanic gases to form acid rain. For example, we can model this process using a Kilauea gas composition, in mole percent (H2O=57.8; HCl=0.9; SO2=17.4; CO2=21.6; H2S=0.2; H2=1.0), and assume the resultant fluid is buffered by atmospheric CO2. Addition of only 0.1 gram of gas to 1 kgram of ancient rainwater reduces the pH to 3.07 and dramatically increases dissolved SO4- (3.8x10^-4 mole/kg), H2S[aq] (1.3x10^-4 mole/kg) and Cl- (4.4x10^-5 mole/kg). Weathering minerals formed by reaction of the above fluid types with martian basalts can vary significantly depending upon initial fluid acidity and solute content. Acid rain and "normal" rain (buffered under high pCO2 conditions) initially alter martian basalt (modeled as the Chassigny parent composition [4]) to, in order of decreasing abundance: Fe-smectite (+/- ferrihydrite), Mn hydroxide, kaolinite, apatite, chalcedony at pH < 5. As pH increase to > 5 then dolomite, calcite, K-feldspar, and dawsonite also precipitate. An important aspect of this modeling is that acid rain can

  1. Conversation Effects on Neural Mechanisms Underlying Reaction Time to Visual Events while Viewing a Driving Scene using MEG

    PubMed Central

    Bowyer, Susan M.; Hsieh, Li; Moran, John E.; Young, Richard A.; Manoharan, Arun; Liao, Chia-cheng Jason; Malladi, Kiran; Yu, Ya-Ju; Chiang, Yow-Ren; Tepley, Norman

    2009-01-01

    Magnetoencephalography (MEG) imaging examined the neural mechanisms that modulate reaction times to visual events while viewing a driving video, with and without a conversation. Twenty-four subjects ages 18–65 were monitored by whole-head MEG. The primary tasks were to monitor a driving video and to depress a foot pedal in response to a small red light presented to the left or below the driving scene at unpredictable times. The behavioral reaction time (RT) to the lights was recorded. The secondary task was a hands-free conversation. The subject pressed a button to answer a ring tone, and then covertly answered pre-recorded non-emotional questions such as “What is your birth date?” RTs for the conversation task (1043ms, SE=65ms) were slightly longer than for the primary task (baseline no conversation (944ms, SE=48ms). During the primary task RTs were inversely related to the amount of brain activity detected by MEG in the right superior parietal lobe (Brodmann’s Area 7). Brain activity was seen in the 200 to 300 ms range after the onset of the red light and in the visual cortex (BA 19) about 85 ms after the red light. Conversation reduced the strengths of these regression relationships and increased mean RT. Conversation may contribute to increased reaction times by (1) damping brain activation in specific regions during specific time windows, or (2) reducing facilitation from attention inputs into those areas. These laboratory findings should not be interpreted as indicative of real-world driving, without on-road validation, and comparison to other in-vehicle tasks. PMID:18992728

  2. Detection and quantification of Renibacterium salmoninarum DNA in salmonid tissues by real-time quantitative polymerase chain reaction analysis

    USGS Publications Warehouse

    Chase, D.M.; Elliott, D.G.; Pascho, R.J.

    2006-01-01

    Renibacterium salmoninarum is an important salmonid pathogen that is difficult to culture. We developed and assessed a real-time, quantitative, polymerase chain reaction (qPCR) assay for the detection and enumeration of R. salmoninarum. The qPCR is based on TaqMan technology and amplifies a 69-base pair (bp) region of the gene encoding the major soluble antigen (MSA) of R. salmoninarum. The qPCR assay consistently detected as few as 5 R. salmoninarum cells per reaction in kidney tissue. The specificity of the qPCR was confirmed by testing the DNA extracts from a panel of microorganisms that were either common fish pathogens or reported to cause false-positive reactions in the enzyme-linked immunosorbent assay (ELISA). Kidney samples from 38 juvenile Chinook salmon (Oncorhynchus tshawytscha) in a naturally infected population were examined by real-time qPCR, a nested PCR, and ELISA, and prevalences of R. salmoninarum detected were 71, 66, and 71%, respectively. The qPCR should be a valuable tool for evaluating the R. salmoninarum infection status of salmonids.

  3. Effect of roasting time of buckwheat groats on the formation of Maillard reaction products and antioxidant capacity.

    PubMed

    Małgorzata, Wronkowska; Konrad, Piskuła Mariusz; Zieliński, Henryk

    2016-04-01

    Changes in the formation of Maillard reaction products and antioxidant capacity of buckwheat, induced by roasting at 160 °C for 30, 40 and 50 min, were evaluated in the study. Furozine, was detected after roasting, in all buckwheat samples. Increase of FIC, the presence of significant amounts of CML and enhanced browning were observed, along with increasing times of roasting. The formation of acrylamide in the obtained buckwheat products was also significantly connected with the time of roasting. A significant degradation was observed in natural antioxidants, as affected by heat treatment time. The colour parameter changed significantly with the increasing of roasting time. Overall, 30min of roasting was beneficial from a nutritional point of view for the obtained buckwheat product.

  4. Identification of the five human Plasmodium species including P. knowlesi by real-time polymerase chain reaction.

    PubMed

    Oddoux, O; Debourgogne, A; Kantele, A; Kocken, C H; Jokiranta, T S; Vedy, S; Puyhardy, J M; Machouart, M

    2011-04-01

    Recently, Plasmodium knowlesi has been recognised as the fifth Plasmodium species causing malaria in humans. Hundreds of human cases infected with this originally simian Plasmodium species have been described in Asian countries and increasing numbers are reported in Europe from travellers. The growing impact of tourism and economic development in South and Southeast Asia are expected to subsequently lead to a further increase in cases both among locals and among travellers. P. knowlesi is easily misidentified in microscopy as P. malariae or P. falciparum. We developed new primers for the rapid and specific detection of this species by low-cost real-time polymerase chain reaction (PCR) and added this method to an already existing panel of primers used for the molecular identification of the other four species in one reaction. Reference laboratories should now be able to identify undisputably and rapidly P. knowlesi, as it is a potentially fatal pathogen.

  5. Estimation of kinetic parameters for enzyme-inhibition reaction models using direct time-dependent equations for reactant concentrations.

    PubMed

    Goličnik, Marko

    2012-03-01

    To facilitate the determination of a reaction type and its kinetics constants for reversible inhibitors of Michaelis-Menten-type enzymes using progress-curve analysis, I present here an explicit equation for direct curve fitting to full time-course data of inhibited enzyme-catalyzed reactions. This algebraic expression involves certain elementary functions where their values are readily available using any standard nonlinear regression program. Hence this allows easy analysis of experimentally observed kinetics without any data conversion prior to fitting. Its implementation gives correct parameter estimates that are in very good agreement with results obtained using both the numerically integrated Michaelis-Menten rate equation or its exact closed-form solution which is expressed in terms of the Lambert W function.

  6. Detection of parvalbumin, a common fish allergen gene in food, by real-time polymerase chain reaction.

    PubMed

    Sun, Min; Liang, Chengzhu; Gao, Hongwei; Lin, Chao; Deng, Mingjun

    2009-01-01

    Fish, as one of the most common causes of IgE-mediated food hypersensitivity, has recently received increasing attention from the food industry and legislative and regulatory agencies. A real-time polymerase chain reaction assay based on TaqMan-MGB probe technology was developed for the detection of parvalbumin, a major fish allergen gene. The assay had a sensitivity up to 5 pg purified fish DNA and had no cross-reaction with other species, such as cattle, sheep, swine, chicken, shrimp, lobster, crab, squid, clam, rice, soybean, maize, and potato. The coefficient of variation for both intra- and interexperimental variability demonstrated high reproducibility and accuracy. The assay proved to be a potential tool for the detection and label management of fish allergens in food.

  7. Real-time nonlinear feedback control of pattern formation in (bio)chemical reaction-diffusion processes: a model study.

    PubMed

    Brandt-Pollmann, U; Lebiedz, D; Diehl, M; Sager, S; Schlöder, J

    2005-09-01

    Theoretical and experimental studies related to manipulation of pattern formation in self-organizing reaction-diffusion processes by appropriate control stimuli become increasingly important both in chemical engineering and cellular biochemistry. In a model study, we demonstrate here exemplarily the application of an efficient nonlinear model predictive control (NMPC) algorithm to real-time optimal feedback control of pattern formation in a bacterial chemotaxis system modeled by nonlinear partial differential equations. The corresponding drift-diffusion model type is representative for many (bio)chemical systems involving nonlinear reaction dynamics and nonlinear diffusion. We show how the computed optimal feedback control strategy exploits the system inherent physical property of wave propagation to achieve desired control aims. We discuss various applications of our approach to optimal control of spatiotemporal dynamics.

  8. Detection of cashew nut DNA in spiked baked goods using a real-time polymerase chain reaction method.

    PubMed

    Brzezinski, Jennifer L

    2006-01-01

    The detection of potentially allergenic foods, such as tree nuts, in food products is a major concern for the food processing industry. A real-time polymerase chain reaction (PCR) method was designed to determine the presence of cashew DNA in food products. The PCR amplifies a 67 bp fragment of the cashew 2S albumin gene, which is detected with a cashew-specific, dual-labeled TaqMan probe. This reaction will not amplify DNA derived from other tree nut species, such as almond, Brazil nut, hazelnut, and walnut, as well as 4 varieties of peanut. This assay was sensitive enough to detect 5 pg purified cashew DNA as well as cashew DNA in a spiked chocolate cookie sample containing 0.01% (100 mg/kg) cashew.

  9. Development of ESI-MS-based continuous enzymatic assay for real-time monitoring of enzymatic reactions of acetylcholinesterase.

    PubMed

    Fu, Qiang; Tang, Jun; Cui, Meng; Zheng, Zhong; Liu, Zhiqiang; Liu, Shuying

    2015-05-15

    The continuous enzymatic assay based on ESI-MS was developed to real-time monitoring of enzymatic reactions of acetylcholinesterase (AChE). The changes of product concentrations were continuously measured. Calibration curves were established for quantitative calculation. By this method, the Michaelis constant (Km) of acetylcholinesterase was determined to be 70.60±0.93μM and Huperzine A as an effective inhibitor of acetylcholinesterase displayed a mixed inhibition with competitive and noncompetitive inhibition behaviors. The half maximal inhibitory concentration (IC50) and inhibition constant (Ki) value of Huperzine A were also calculated as 48.51±1.16nM and 26.73±0.27nM, respectively. This method provides the rapid and accurate ways to monitor enzyme reactions.

  10. Real-time nonlinear feedback control of pattern formation in (bio)chemical reaction-diffusion processes: A model study

    NASA Astrophysics Data System (ADS)

    Brandt-Pollmann, U.; Lebiedz, D.; Diehl, M.; Sager, S.; Schlöder, J.

    2005-09-01

    Theoretical and experimental studies related to manipulation of pattern formation in self-organizing reaction-diffusion processes by appropriate control stimuli become increasingly important both in chemical engineering and cellular biochemistry. In a model study, we demonstrate here exemplarily the application of an efficient nonlinear model predictive control (NMPC) algorithm to real-time optimal feedback control of pattern formation in a bacterial chemotaxis system modeled by nonlinear partial differential equations. The corresponding drift-diffusion model type is representative for many (bio)chemical systems involving nonlinear reaction dynamics and nonlinear diffusion. We show how the computed optimal feedback control strategy exploits the system inherent physical property of wave propagation to achieve desired control aims. We discuss various applications of our approach to optimal control of spatiotemporal dynamics.

  11. In Site Analysis of a High Temperature Cure Reaction in Real Time Using Modulated Fiber-Optic FT-Raman Spectroscopy

    NASA Technical Reports Server (NTRS)

    Cooper, John; Aust, Jeffrey F.; Wise, Kent L.; Jensen, Brian J.

    1999-01-01

    The vibrational spectrum of a high temperature (330 C) polymerization reaction was successfully monitored in real time using a modulated fiber-optic FT-Raman spectrometer. A phenylethynyl terminated monomer was cured, and spectral evidence for two different reaction products was acquired. The products are a conjugated polyene chain and a cyclized trimer. This is the first report describing the use of FT-Raman spectroscopy to monitor a high temperature (greater than 250 C) reaction in real time.

  12. Near-IR absorbance changes and electrogenic reactions in the microsecond-to-second time domain in Photosystem I.

    PubMed

    Vassiliev, I R; Jung, Y S; Mamedov, M D; Semenov AYu; Golbeck, J H

    1997-01-01

    The back-reaction kinetics in Photosystem I (PS I) were studied on the microsecond-to-s time scale in cyanobacterial preparations, which differed in the number of iron-sulfur clusters to assess the contributions of particular components to the reduction of P700+. In membrane fragments and in trimeric P700-FA/FB complexes, the major contribution to the absorbance change at 820 nm (delta A820) was the back-reaction of FA- and/or FB- with lifetimes of approximately 10 and 80 ms (approximately 10% and 40% relative amplitude). The decay of photoinduced electric potential (delta psi) across a membrane with directionally incorporated P700-FA/FB complexes had similar kinetics. HgCl2-treated PS I complexes, which contain FA but no FB, retain both of these kinetic components, indicating that neither can be assigned uniquely to a specific acceptor. These results suggest that FA- reduces P700+ directly and argue for a rapid electron equilibration between FA and FB, which would eliminate their kinetic distinction in a back-reaction. In PsaC-depleted P700-Fx cores, as well as in P700-FA/FB complexes with chemically reduced FA and FB, the major contribution to the delta A820 and the delta psi decay is a biphasic back-reaction of F-X (approximately 400 microseconds and 1.5 ms) with some contribution from A-1 (approximately 10 microseconds and 100 microseconds), the latter of which is variable depending on experimental conditions. The delta A820 decay in a P700-A1 core devoid of all iron-sulfur clusters comprises two phases with lifetimes of 10 microseconds and 130 microseconds (2.7:1 ratio). The biexponential back-reaction kinetics found for each of the electron acceptors may be related to existence of different conformational states of the PS I complex. In all preparations studied, excitation at 532 nm with flash energies exceeding 10 mJ gives rise to formation of antenna 3Chl, which also contributes to delta A820 decay on the tens-of-microsecond time scale. A distinction between

  13. Quantitation of Bacillus clausii in biological samples by real-time polymerase chain reaction.

    PubMed

    Perotti, Mario; Mancini, Nicasio; Cavallero, Annalisa; Carletti, Silvia; Canducci, Filippo; Burioni, Roberto; Clementi, Massimo

    2006-06-01

    A real-time PCR assay targeting the highly specific erm34 sequence of Bacillus clausii DNA was developed and optimized. The quantitative assay showed a sensitivity level of 10(2) CFU/microl of sample. The method may represent a useful tool for monitoring the role of B. clausii as probiotic in vivo.

  14. A time-periodic reaction-diffusion epidemic model with infection period

    NASA Astrophysics Data System (ADS)

    Zhang, Liang; Wang, Zhi-Cheng

    2016-10-01

    In this paper, we propose a time-periodic and diffusive SIR epidemic model with constant infection period. By introducing the basic reproduction number R_0 via a next generation operator for this model, we show that the disease goes extinction if R_0 < 1; while the disease is uniformly persistent if R_0 > 1.

  15. Time Required to Initiate a Defensive Reaction to Direct and Feint Attacks in Fencing.

    PubMed

    Gutiérrez-Davila, Marcos; Rojas, F Javier; Gutiérrez-Cruz, Carmen; García, Carlos; Navarro, Enrique

    2016-12-01

    The two-fold purpose of this study was to analyze the time required by a fencer to initiate a defensive action in response to a direct attack, which involves identifying when the defending fencer detects the just-noticeable difference, and, secondly, to assess the effect that an attacker's rapid armed hand movement (feint attack) has on the time required to initiate a defensive move. Twenty-four elite fencers and a fencing master were included in the study. Four adapted force plates were installed on a scaffold used as a fencing piste. A 3D video analysis system recorded the location of 2 markers installed on the fencing master's shoulder and sword. The results confirm that the defending fencer has a mean movement time of 0.353 ± 0.028 s to perform the defensive action, which provides an advantage over the attacking fencer. The velocity of movement in the peripheral visual field has no influence on the time required by elite fencers to initiate a defensive action. This confirms the crucial role that response inhibition processes play when nonrelevant actions are perceived. Kinematic analysis of markers suggests that the eye movements of elite fencers are not the only source of information used while observing an attack.

  16. On-chip real-time single-copy polymerase chain reaction in picoliter droplets

    SciTech Connect

    Beer, N R; Hindson, B; Wheeler, E; Hall, S B; Rose, K A; Kennedy, I; Colston, B

    2007-04-20

    The first lab-on-chip system for picoliter droplet generation and PCR amplification with real-time fluorescence detection has performed PCR in isolated droplets at volumes 10{sup 6} smaller than commercial real-time PCR systems. The system utilized a shearing T-junction in a silicon device to generate a stream of monodisperse picoliter droplets that were isolated from the microfluidic channel walls and each other by the oil phase carrier. An off-chip valving system stopped the droplets on-chip, allowing them to be thermal cycled through the PCR protocol without droplet motion. With this system a 10-pL droplet, encapsulating less than one copy of viral genomic DNA through Poisson statistics, showed real-time PCR amplification curves with a cycle threshold of {approx}18, twenty cycles earlier than commercial instruments. This combination of the established real-time PCR assay with digital microfluidics is ideal for isolating single-copy nucleic acids in a complex environment.

  17. Reaction time to changes in the tempo of acoustic pulse trains.

    NASA Technical Reports Server (NTRS)

    Smith, R. P.; Warm, J. S.; Westendorf, D. H.

    1973-01-01

    Investigation of the ability of human observers to detect accelerations and decelerations in the rate of presentation of pulsed stimuli, i.e., changes in the tempo of acoustic pulse trains. Response times to accelerations in tempo were faster than to decelerations. Overall speed of response was inversely related to the pulse repetition rate.

  18. A Comparison of Sequential Sampling Models for Two-Choice Reaction Time

    ERIC Educational Resources Information Center

    Ratcliff, Roger; Smith, Philip L.

    2004-01-01

    The authors evaluated 4 sequential sampling models for 2-choice decisions--the Wiener diffusion, Ornstein-Uhlenbeck (OU) diffusion, accumulator, and Poisson counter models--by fitting them to the response time (RT) distributions and accuracy data from 3 experiments. Each of the models was augmented with assumptions of variability across trials in…

  19. R/S analysis of reaction time in Neuron Type Test for human activity in civil aviation

    NASA Astrophysics Data System (ADS)

    Zhang, Hong-Yan; Kang, Ming-Cui; Li, Jing-Qiang; Liu, Hai-Tao

    2017-03-01

    Human factors become the most serious problem leading to accidents of civil aviation, which stimulates the design and analysis of Neuron Type Test (NTT) system to explore the intrinsic properties and patterns behind the behaviors of professionals and students in civil aviation. In the experiment, normal practitioners' reaction time sequences, collected from NTT, exhibit log-normal distribution approximately. We apply the χ2 test to compute the goodness-of-fit by transforming the time sequence with Box-Cox transformation to cluster practitioners. The long-term correlation of different individual practitioner's time sequence is represented by the Hurst exponent via Rescaled Range Analysis, also named by Range/Standard deviation (R/S) Analysis. The different Hurst exponent suggests the existence of different collective behavior and different intrinsic patterns of human factors in civil aviation.

  20. Identification of Aedes aegypti and Its Respective Life Stages by Real-Time Polymerase Chain Reaction

    DTIC Science & Technology

    2004-12-01

    potential disease transmission risk and timely implementation of appropriate control measures, Aedes aegypti is the primary vector of dengue fever and...8217 Dengue fever is the most significant mosquito-borne viral disease today, with a risk comparable to that for malaria, i,e,, two-fifths of the world’s...human population, ’̂̂ Although malarial disease can be prevented by prophylaxis and yellow fever by immunization, dengue fever prophylaxis does not

  1. Dissociating models of visual working memory by reaction-time distribution analysis.

    PubMed

    Park, Hyung-Bum; Zhang, Weiwei; Hyun, Joo-Seok

    2017-02-01

    There have been heated debates on whether visual working memory (VWM) represents information in discrete-slots or a reservoir of flexible-resources. However, one key aspect of the models has gone unnoticed, the speed of processing when stored information in memory is assessed for accuracy. The present study evaluated contrasting predictions from the two models regarding the change detection decision times spent on the assessment of stored information by estimating the ex-Gaussian parameters from change detection RT distributions across different set sizes (2, 4, 6, or 8). The estimation showed that the Gaussian components μ and σ became larger as the set size increased from 2 to 4, but stayed constant as it reached 6 and 8, with an exponential component τ increasing at above-capacity set sizes. Moreover, we found that an individual's capacity limit correlates with the memory set size where the Gaussian μ reaches a plateau. These results indicate that the decision time for assessing in-memory items is constant regardless of memory set sizes whereas the time for the remaining not-in-memory items increases as the set size exceeds VWM storage capacity. The findings suggest that the discrete-slot model explains the observed RT distributions better than the flexible-resource model.

  2. Development of a real time polymerase chain reaction assay for equine encephalosis virus.

    PubMed

    Rathogwa, N M; Quan, M; Smit, J Q; Lourens, C; Guthrie, A J; van Vuuren, M

    2014-01-01

    Equine encephalosis virus (EEV) is the cause of equine encephalosis. The disease is similar to mild forms of African horse sickness (AHS) and the two diseases are easily confused. Laboratory identification and serotyping of EEV is based on viral isolation in BHK-21 cells and a viral plaque inhibition neutralisation test. These procedures are time-consuming and therefore a more rapid diagnostic assay for EEV that can distinguish EEV from African horse sickness virus (AHSV) infections was developed. The S7 (VP7) gene from 38 EEV isolates representing all seven serotypes was amplified and sequenced. A conserved region at the 5' end of the gene was identified and used to design group-specific EEV primers and a TaqMan(®) MGB™ hydrolysis probe. The efficiency of the EEV real-time RT-PCR assay was 81%. The assay was specific, as it did not detect any of the nine serotypes of AHSV, nor 24 serotypes of bluetongue virus (BTV) and sensitive, with a 95% limit of detection of 10(2.9) TCID50/ml blood (95% confidence interval: 10(2.7) to 10(3.3)). The real-time format was selected because of its convenience, sensitivity and ability to produce results rapidly.

  3. Determination of the primary charge separation rate in isolated photosystem II reaction centers with 500-fs time resolution

    SciTech Connect

    Wasielewski, M.R.; Johnson, D.G. ); Seibert, M. ); Govindjee )

    1989-01-01

    The authors have measured directly the rate of formation of the oxidized chlorophyll a electron donor (P680+) and the reduced electron acceptor pheophytin a{sup {minus}} (Pheoa{sup {minus}}) following excitation of isolated spinach photosystem II reaction centers at 4{degree}C. The reaction-center complex consists of D{sub 1}, D{sub 2}, and cytochrome b-559 proteins and was prepared by a procedure that stabilizes the protein complex. Transient absorption difference spectra were measured from 440 to 850 nm as a function of time with 500-fs resolution following 610-nm laser excitation. The formation of P680+-Pheoa{sup {minus}} is indicated by the appearance of a band due to P680+ at 820 nm and corresponding absorbance changes at 505 and 540 nm due to formation of Pheoa{sup {minus}}. The appearance of the 820-nm band is monoexponential with {tau} = 3.0 {plus minus} 0.6 ps. Treatment of the photosystem II reaction centers with sodium dithionite and methyl viologen followed by exposure to laser excitation, conditions known to result in accumulation of Pheoa{sup {minus}}, results in formation of a transient absorption spectrum due to {sup 1*}P680. They find no evidence for an electron acceptor that precedes the formation of Pheoa{sup {minus}}.

  4. Channels of the corpus callosum. Evidence from simple reaction times to lateralized flashes in the normal and the split brain.

    PubMed

    Iacoboni, M; Zaidel, E

    1995-06-01

    We studied 75 normal subjects and three commissurotomized patients using unimanual simple reaction times to lateralized flashes as a behavioural estimate of interhemispheric transmission time. Three different versions of the paradigm were performed: (i) the basic task; (ii) a motor task, with an increased complexity of the motor response; and (iii) a visual task, with an increased complexity of the visual stimulus presentation. We tested two hypotheses. First, that the new versions of the simple reaction time task result in shifts in hemispheric specialization for processing motor output (indicated by a main effect of response hand) or visual input (indicated by a main effect of visual field) alone, without affecting callosal transmission. In that case normals and split brain patients would show no significant task by response hand by visual field interaction and no significant task by crossed-uncrossed difference interaction. Secondly, that the new versions of the task affect callosal transfer. In that case, normals, but not split brain patients, would show a significant task by response hand by visual field interaction and a significant task by crossed-uncrossed difference interaction. Results are consistent with the latter hypothesis, showing that the motor task significantly changed the response hand by visual field interaction and the crossed-uncrossed difference, but only in normal subjects, perhaps producing a switch in the callosal channel subserving the interhemispheric transfer.

  5. Time-sliced ion-velocity imaging study of the reaction Y + O2 → YO + O.

    PubMed

    Honma, Kenji; Matsumoto, Yoshiteru

    2011-05-14

    The oxidation reaction dynamics of the gas-phase yttrium atoms by oxygen molecules was studied under crossed-beam conditions. The product YO was detected using a time-of-flight mass spectrometer combined with laser single-photon ionization. An acceleration lens system designed for the ion-velocity mapping conditions, a two-dimensional (2-D) detector, and a time-slicing technique were used to obtain the velocity and angular distributions of the products. Two ionization wavelengths were used for the internal (vibrational and/or electronic) energy selective detection of YO. The single photon of the shorter wavelength (202.0 nm) can ionize all states of YO(X (2)Σ, A' (2)Δ, and A (2)Π), while electronically excited YO(A' and A) are dominantly ionized at a longer wavelength (285.0 nm). Time-sliced images were converted to the velocity and angular distributions in the center-of-mass frame. The general features of the velocity distributions of YO, determined at two wavelengths, were well represented by those expected from the statistical energy disposal model. The forward-backward symmetry was also observed for two images. These results suggest that the reaction proceeds via long-lived intermediates, and that this mechanism is consistent with previous chemiluminescence/LIF studies.

  6. Age-related differences in the neural correlates of trial-to-trial variations of reaction time

    PubMed Central

    Adleman, Nancy E.; Chen, Gang; Reynolds, Richard C.; Frackman, Anna; Razdan, Varun; Weissman, Daniel H.; Pine, Daniel S.; Leibenluft, Ellen

    2016-01-01

    Intra-subject variation in reaction time (ISVRT) is a developmentally-important phenomenon that decreases from childhood through young adulthood in parallel with the development of executive functions and networks. Prior work has shown a significant association between trial-by-trial variations in reaction time (RT) and trial-by-trial variations in brain activity as measured by the blood-oxygenated level-dependent (BOLD) response in functional magnetic resonance imaging (fMRI) studies. It remains unclear, however, whether such “RT-BOLD” relationships vary with age. Here, we determined whether such trial-by-trial relationships vary with age in a cross-sectional design. We observed an association between age and RT-BOLD relationships in 11 clusters located in visual/occipital regions, frontal and parietal association cortex, precentral/postcentral gyrus, and thalamus. Some of these relationships were negative, reflecting increased BOLD associated with decreased RT, manifesting around the time of stimulus presentation and positive several seconds later. Critically for present purposes, all RT-BOLD relationships increased with age. Thus, RT-BOLD relationships may reflect robust, measurable changes in the brain-behavior relationship across development. PMID:27239972

  7. Comparison of two real-time quantitative polymerase chain reaction strategies for minimal residual disease evaluation in lymphoproliferative disorders: correlation between immunoglobulin gene mutation load and real-time quantitative polymerase chain reaction performance.

    PubMed

    Della Starza, Irene; Cavalli, Marzia; Del Giudice, Ilaria; Barbero, Daniela; Mantoan, Barbara; Genuardi, Elisa; Urbano, Marina; Mannu, Claudia; Gazzola, Anna; Ciabatti, Elena; Guarini, Anna; Foà, Robin; Galimberti, Sara; Piccaluga, Pierpaolo; Gaidano, Gianluca; Ladetto, Marco; Monitillo, Luigia

    2014-09-01

    We compared two strategies for minimal residual disease evaluation of B-cell lymphoproliferative disorders characterized by a variable immunoglobulin heavy chain (IGH) genes mutation load. Twenty-five samples from chronic lymphocytic leukaemia (n = 18) or mantle cell lymphoma (n = 7) patients were analyzed. Based on IGH variable region genes, 22/25 samples carried > 2% mutations, 20/25 > 5%. In the IGH joining region genes, 23/25 samples carried > 2% mutations, 18/25 > 5%. Real-time quantitative polymerase chain reaction was performed on IGH genes using two strategies: method A utilizes two patient-specific primers, whereas method B employs one patient-specific and one germline primer, with different positions on the variable, diversity and joining regions. Twenty-three samples (92%) resulted evaluable using method A, only six (24%) by method B. Method B poor performance was specifically evident among mutated IGH variable/joining region cases, although no specific mutation load above, which the real-time quantitative polymerase chain reaction failed was found. The molecular strategies for minimal residual disease evaluation should be adapted to the B-cell receptor features of the disease investigated.

  8. Interlaboratory validation data on real-time polymerase chain reaction detection for unauthorized genetically modified papaya line PRSV-YK.

    PubMed

    Nakamura, Kosuke; Kondo, Kazunari; Akiyama, Hiroshi; Ishigaki, Takumi; Noguchi, Akio; Katsumata, Hiroshi; Takasaki, Kazuto; Futo, Satoshi; Sakata, Kozue; Fukuda, Nozomi; Mano, Junichi; Kitta, Kazumi; Tanaka, Hidenori; Akashi, Ryo; Nishimaki-Mogami, Tomoko

    2016-06-01

    This article is referred to research article entitled "Whole genome sequence analysis of unidentified genetically modified papaya for development of a specific detection method" (Nakamura et al., 2016) [1]. Real-time polymerase chain reaction (PCR) detection method for unauthorized genetically modified (GM) papaya (Carica papaya L.) line PRSV-YK (PRSV-YK detection method) was developed using whole genome sequence data (DDBJ Sequenced Read Archive under accession No. PRJDB3976). Interlaboratory validation datasets for PRSV-YK detection method were provided. Data indicating homogeneity of samples prepared for interlaboratory validation were included. Specificity and sensitivity test data for PRSV-YK detection method were also provided.

  9. Description of nucleon-transfer and fusion reactions within time-dependent approaches and coupled-channel method

    SciTech Connect

    Samarin, V. V.

    2015-01-15

    The time-dependent Schrödinger equation and the method of perturbed stationary states that is based on the expansion of the total wave function for the system of two nuclear cores and a nucleon in a set of nucleon two-center functions are used to describe nucleon transfers and fusion in low-energy nuclear reactions. A set of multichannel equations that couple the relative motion of nuclei to the motion of the nucleon is obtained. The kinetic-energy coupling matrix is similar to the coupling matrix for collective excitations of nuclei.

  10. Proton-coupled electron transfer in tyrosine and a β-hairpin maquette: reaction dynamics on the picosecond time scale.

    PubMed

    Pagba, Cynthia V; Chi, San-Hui; Perry, Joseph; Barry, Bridgette A

    2015-02-12

    In proteins, proton-coupled electron transfer (PCET) can involve the transient oxidation and reduction of the aromatic amino acid tyrosine. Due to the short life time of tyrosyl radical intermediates, transient absorption spectroscopy provides an important tool in deciphering electron-transfer mechanisms. In this report, the photoionization of solution tyrosine and tyrosinate was investigated using transient, picosecond absorption spectroscopy. The results were compared to data acquired from a tyrosine-containing β-hairpin peptide. This maquette, peptide A, is an 18-mer that exhibits π-π interaction between tyrosine (Y5) and histidine (H14). Y5 and H14 carry out an orthogonal PCET reaction when Y5 is oxidized in the mid-pH range. Photolysis of all samples (280 nm, instrument response: 360 fs) generated a solvated electron signal within 3 ps. A signal from the S1 state and a 410 nm signal from the neutral tyrosyl radical were also formed in 3 ps. Fits to S1 and tyrosyl radical decay profiles revealed biphasic kinetics with time constants of 10-50 and 400-1300 ps. The PCET reaction at pH 9 was associated with a significant decrease in the rate of tyrosyl radical and S1 decay compared to electron transfer (ET) alone (pH 11). This pH dependence was observed both in solution and peptide samples. The pH 9 reaction may occur with a sequential electron-transfer, proton-transfer (ETPT) mechanism. Alternatively, the pH 9 reaction may occur by coupled proton and electron transfer (CPET). CPET would be associated with a reorganization energy larger than that of the pH 11 reaction. Significantly, the decay kinetics of S1 and the tyrosyl radical were accelerated in peptide A compared to solution samples at both pH values. These data suggest either an increase in electronic coupling or a specific, sequence-dependent interaction, which facilitates ET and PCET in the β hairpin.

  11. Community reaction to aircraft noise: time-of-day penalty and tradeoff between levels of overflights.

    PubMed

    Miedema, H M; Vos, H; de Jong, R G

    2000-06-01

    A decrease in the level of sound events can compensate for an increase in the level of other events, but noise metrics assume different tradeoffs. Noise metrics also differ in the penalty applied to noise in the evening and to noise in the night, and in the definition of these periods. These two aspects of noise metrics, i.e., the tradeoff and the penalty for the nighttime (23-7h), are investigated. A general model of the relation between SELs of sound events (aircraft overflights) and noise annoyance is presented which allows for a wide range of tradeoffs and time-of-day penalties. The (tradeoff and time-of-day penalty) parameters of the model are fitted to the data from an aircraft noise study conducted around Amsterdam Airport Schiphol, which is especially suited for investigating the tradeoff and time-of-day penalties. It was found that in this study the tradeoff between the levels of events in metrics based on L(Aeq)'s, such as L(Aeq)(24 h), DNL, and DENL, is approximately correct for the prediction of noise annoyance. Furthermore, it was found that the strongest correlation with annoyance is obtained with a nighttime penalty of circa 10 dB. No suitable data were available for further tests of the tradeoff. The result with respect to the nighttime penalty was weakly further supported by the outcome of analyses of the original data from four other aircraft noise surveys (one survey conducted around British airports, and three coordinated surveys carried out around Paris Orly, Amsterdam Schiphol, and Glasgow Abbotsinch).

  12. On the Way to Experimental Test of the Time Reversal Invariance in the Nuclear Reactions

    PubMed Central

    Skoy, Vadim R.; Ino, Takashi; Masuda, Yasuhiro; Muto, Suguru; Kim, Guinyun

    2005-01-01

    Time (T) violation can be related with charge-parity (CP) violation through the CPT theorem. The CP violation was discovered experimentally in the K0-meson decays about 35 years ago. The T violating interaction related with the CP violation violates parity as well. However, an extension of the theory beyond the locality of the interactions might violate the CPT theorem. The result of the CPLEAR experiment [1], which has given direct evidence of T violation in the elementary-particle phenomena, could be considered under assumption of the CPT invariance. PMID:27308170

  13. Real-time polymerase chain reaction detection of fishmeal in feedstuffs.

    PubMed

    Martín, Irene; García, Teresa; Rojas, Maria; Pegels, Nicolette; Pavón, Miguel Angel; Hernández, Pablo E; González, Isabel; Martín, Rosario

    2010-01-01

    A SYBR Green PCR system was developed for detection of fishmeal in feedstuffs. The real-time PCR method combines the use of fish-specific primers that amplify an 87 base pair (bp) fragment of the mitochondrial 12S ribosomal RNA gene from fish species, and a positive control primer pair that amplifies a 99 bp fragment of the nuclear 18S ribosomal RNA gene in all eukaryotic organisms. The specificity of the primers was tested against 52 animal species and six plant species. Reference feedstuff samples were successfully tested for the presence of fishmeal, demonstrating the applicability of the assay to feedstuffs.

  14. Explicit reformulations of time-dependent solution for a Michaelis-Menten enzyme reaction model.

    PubMed

    Golicnik, Marko

    2010-11-01

    The exact closed-form solution to the Michaelis-Menten equation is expressed in terms of the Lambert W(x) function. However, the utility of this solution is limited because the W(x) function is not widely available in curve-fitting software. Based on various approximations to the W(x) function, different explicit equations expressed in terms of the elementary functions are proposed here as useful shortcuts to fit time depletion of substrate concentration directly to progress curves using commonly available nonlinear regression computer programs. The results are compared with those obtained by fitting other algebraic equations that have been proposed previously in the literature.

  15. Characterization of self-propagating formation reactions in Ni/Zr multilayered foils using reaction heats, velocities, and temperature-time profiles

    DOE PAGES

    Barron, S. C.; Knepper, R.; Walker, N.; ...

    2011-01-11

    We report on intermetallic formation reactions in vapor-deposited multilayered foils of Ni/Zr with 70 nm bilayers and overall atomic ratios of Ni:Zr, 2 Ni:Zr, and 7 Ni:2 Zr. The sequence of alloy phase formation and the stored energy is evaluated at slow heating rates (~1 K/s) using differential scanning calorimetry (DSC) traces to 725ºC. All three chemistries initially form a Ni-Zr amorphous phase which crystallizes first to the intermetallic NiZr. The heat of reaction to the final phase is 34-36 kJ/mol atom for all chemistries. Intermetallic formation reactions are also studied at rapid heating rates (greater than 105 K/s) inmore » high temperature, self-propagating reactions which can be ignited in these foils by an electric spark. We find that reaction velocities and maximum reaction temperatures (Tmax) are largely independent of foil chemistry at 0.6 ± 0.1 m/s and 1220 ± 50 K, respectively, and that the measured Tmax is more than 200 K lower than predicted adiabatic temperatures (Tad). The difference between Tmax and Tad is explained by the prediction that transformation to the final intermetallic phases occurs after Tmax and results in the release of 20-30 % of the total heat of reaction and a delay in rapid cooling.« less

  16. Performance of robust regression methods in real-time polymerase chain reaction calibration.

    PubMed

    Orenti, Annalisa; Marubini, Ettore

    2014-12-09

    The ordinary least squares (OLS) method is routinely used to estimate the unknown concentration of nucleic acids in a given solution by means of calibration. However, when outliers are present it could appear sensible to resort to robust regression methods. We analyzed data from an External Quality Control program concerning quantitative real-time PCR and we found that 24 laboratories out of 40 presented outliers, which occurred most frequently at the lowest concentrations. In this article we investigated and compared the performance of the OLS method, the least absolute deviation (LAD) method, and the biweight MM-estimator in real-time PCR calibration via a Monte Carlo simulation. Outliers were introduced by replacement contamination. When contamination was absent the coverages of OLS and MM-estimator intervals were acceptable and their widths small, whereas LAD intervals had acceptable coverages at the expense of higher widths. In the presence of contamination we observed a trade-off between width and coverage: the OLS performance got worse, the MM-estimator intervals widths remained short (but this was associated with a reduction in coverages), while LAD intervals widths were constantly larger with acceptable coverages at the nominal level.

  17. Construction and Evaluation of Cytomegalovirus DNA Quantification System with Real-Time Detection Polymerase Chain Reaction

    PubMed Central

    Hatayama, Yuki; Hashimoto, Yuki; Hara, Ayako; Motokura, Toru

    2016-01-01

    Background For patients with reactivation of human cytomegalovirus (CMV), a highly sensitive and accurate CMV quantification system is essential to monitor viral load. Methods We constructed a real-time detection PCR (RTD-PCR) system for CMV DNA and evaluated its linearity, lower detection limit, dynamic range and accuracy using two CMV standards. We used 219 clinical samples derived from 101 patients to compare the system with the pp65 antigen test. Results The 95% detection limit was determined to be 556 IU/mL (95% CI, 440–797 IU/mL), and the quantification range was between 102 and 106 copies or IU/mL (r = 0.996, 0.999, respectively). The coefficients of variation of inter-assay reproducibility assessed in each three different runs were 2.5% at 1,000 IU/mL and 1.6% at 10,000 IU/mL. The coefficients of variation of intra-assay variability by testing the same samples three times in a single run were 1.8–3.6% and 0.4–1.9%, respectively. The concordance between antigenemia and plasma or serum CMV DNA levels was a good correlation (r = 0.695, P < 0.01). Conclusion We constructed the RTD-PCR system which enables accurate evaluation of CMV reactivation by monitoring of viral load in immunosuppressed or immunocompromised patients. PMID:27708537

  18. Advanced Precursor Reaction Processing for Cu(InGa)(SeS)2 Solar Cells

    SciTech Connect

    Shafarman, William N.

    2015-10-12

    This project “Advanced Precursor Reaction Processing for Cu(InGa)(SeS)2 Solar Cells”, completed by the Institute of Energy Conversion (IEC) at the University of Delaware in collaboration with the Department of Chemical Engineering at the University of Florida, developed the fundamental understanding and technology to increase module efficiency and improve the manufacturability of Cu(InGa)(SeS)2 films using the precursor reaction approach currently being developed by a number of companies. Key results included: (1) development of a three-step H2Se/Ar/H2S reaction process to control Ga distribution through the film and minimizes back contact MoSe2 formation; (2) Ag-alloying to improve precursor homogeneity by avoiding In phase agglomeration, faster reaction and improved adhesion to allow wider reaction process window; (3) addition of Sb, Bi, and Te interlayers at the Mo/precursor junction to produce more uniform precursor morphology and improve adhesion with reduced void formation in reacted films; (4) a precursor structure containing Se and a reaction process to reduce processing time to 5 minutes and eliminate H2Se usage, thereby increasing throughput and reducing costs. All these results were supported by detailed characterization of the film growth, reaction pathways, thermodynamic assessment and device behavior.

  19. In-situ time resolved synchrotron powder diffraction studies of synthesis and chemical reactions

    SciTech Connect

    Norby, P.

    1995-09-01

    Equipment for time and temperature dependent powder diffraction has been developed, especially in order to be able to study hydrothermal syntheses of zeolites. The system is very versatile and has so far been used to study e.g. hydrothermal syntheses of zeolites and aluminophosphates, syntheses of layered phosphates, formation of Sorel cements, dehydration and phase transformations of zeolites, solid state synthesis of lanthanum manganites, ion exchange of zeolites using molten salt, and oxidation/reduction of lanthanum manganites at high temperatures. The sample is contained in quartz capillaries and is heated using a stream of hot air. External pressure can be applied allowing hydrothermal syntheses at temperatures up to 200 C to be performed. Controlled atmosphere is obtained by flowing gas or a mixture of gases through the capillary.

  20. Reconciling transition path time and rate measurements in reactions with large entropic barriers

    NASA Astrophysics Data System (ADS)

    Makarov, Dmitrii E.

    2017-02-01

    Recent experiments and simulation studies showed that protein/DNA folding barriers inferred from folding rates or from potentials of mean force are often much higher than the barriers estimated from the distributions of transition path times. Here a toy model is used to explain a possible origin of this effect: It is shown that when the transition in question involves an entropic barrier, the one-dimensional Langevin model commonly used to interpret experimental data, while adequately predicting the transition rate, fails to describe the properties of the subset of the trajectories that form the transition path ensemble; the latter may still be describable in terms of a one-dimensional model, but with a different potential, just as observed experimentally.

  1. Expression of nisin genes in cheese--a quantitative real-time polymerase chain reaction approach.

    PubMed

    Trmčić, A; Monnet, C; Rogelj, I; Bogovič Matijašić, B

    2011-01-01

    The role of bacteriocins in different environments has not been thoroughly explained, mainly because of the difficulties related to the detection of their production. Nisin, an antimicrobial peptide produced by Lactococcus lactis has a long history of safe use in food products and has been studied from many aspects of genetics, biosynthesis, immunity, regulation, and mode of action. Still, some aspects concerning the dynamics of nisin gene expression remain unknown, especially in complex media like cheese. The main objective of the present study was to quantify in a cheese-like medium the expression of nisin genes in L. lactis M78, a well-characterized nisin A producer isolated from raw milk. The expression of all 11 genes involved in nisin biosynthesis was evaluated during cheese production by real-time reverse transcription-PCR. Total RNA was extracted from cheeses using a direct extraction method without prior separation of microbial cells. The M78 strain grew well in experimental cheeses, producing detectable amounts of nisin after 4 h of fermentation. The presence of nisin as an activator modified both the expression of nisin genes and the accumulation of active nisin. Four groups could be distinguished based on gene expression as a function of time: nisA, nisFEG, nisRK and nisBTCIP. Based on nisin-producing strain growth, nisin activity, function of nisin genes, and their location, correlations were established that contribute to the explanation of regulation of nisin biosynthesis and immunity. This study is the first in which the evolution of bacteriocin gene transcripts has been quantified rigorously in a cheese-like medium.

  2. Faster Synthesis of Beta-Diketonate Ternary Europium Complexes: Elapsed Times & Reaction Yields.

    PubMed

    Lima, Nathalia B D; Silva, Anderson I S; Gerson, P C; Gonçalves, Simone M C; Simas, Alfredo M

    2015-01-01

    β-diketonates are customary bidentate ligands in highly luminescent ternary europium complexes, such as Eu(β-diketonate)3(L)2, where L stands for a nonionic ligand. Usually, the syntheses of these complexes start by adding, to an europium salt such as EuCl3(H2O)6, three equivalents of β-diketonate ligands to form the complexes Eu(β-diketonate)3(H2O)2. The nonionic ligands are subsequently added to form the target complexes Eu(β-diketonate)3(L)2. However, the Eu(β-diketonate)3(H2O)2 intermediates are frequently both difficult and slow to purify by recrystallization, a step which usually takes a long time, varying from days to several weeks, depending on the chosen β-diketonate. In this article, we advance a novel synthetic technique which does not use Eu(β-diketonate)3(H2O)2 as an intermediate. Instead, we start by adding 4 equivalents of a monodentate nonionic ligand L straight to EuCl3(H2O)6 to form a new intermediate: EuCl3(L)4(H2O)n, with n being either 3 or 4. The advantage is that these intermediates can now be easily, quickly, and efficiently purified. The β-diketonates are then carefully added to this intermediate to form the target complexes Eu(β-diketonate)3(L)2. For the cases studied, the 20-day average elapsed time reduced to 10 days for the faster synthesis, together with an improvement in the overall yield from 42% to 69%.

  3. Faster Synthesis of Beta-Diketonate Ternary Europium Complexes: Elapsed Times & Reaction Yields

    PubMed Central

    Lima, Nathalia B. D.; Silva, Anderson I. S.; Gerson, P. C.; Gonçalves, Simone M. C.; Simas, Alfredo M.

    2015-01-01

    β-diketonates are customary bidentate ligands in highly luminescent ternary europium complexes, such as Eu(β-diketonate)3(L)2, where L stands for a nonionic ligand. Usually, the syntheses of these complexes start by adding, to an europium salt such as EuCl3(H2O)6, three equivalents of β-diketonate ligands to form the complexes Eu(β-diketonate)3(H2O)2. The nonionic ligands are subsequently added to form the target complexes Eu(β-diketonate)3(L)2. However, the Eu(β-diketonate)3(H2O)2 intermediates are frequently both difficult and slow to purify by recrystallization, a step which usually takes a long time, varying from days to several weeks, depending on the chosen β-diketonate. In this article, we advance a novel synthetic technique which does not use Eu(β-diketonate)3(H2O)2 as an intermediate. Instead, we start by adding 4 equivalents of a monodentate nonionic ligand L straight to EuCl3(H2O)6 to form a new intermediate: EuCl3(L)4(H2O)n, with n being either 3 or 4. The advantage is that these intermediates can now be easily, quickly, and efficiently purified. The β-diketonates are then carefully added to this intermediate to form the target complexes Eu(β-diketonate)3(L)2. For the cases studied, the 20-day average elapsed time reduced to 10 days for the faster synthesis, together with an improvement in the overall yield from 42% to 69%. PMID:26710103

  4. A farewell to brake reaction times? Kinematics-dependent brake response in naturalistic rear-end emergencies.

    PubMed

    Markkula, Gustav; Engström, Johan; Lodin, Johan; Bärgman, Jonas; Victor, Trent

    2016-10-01

    Driver braking behavior was analyzed using time-series recordings from naturalistic rear-end conflicts (116 crashes and 241 near-crashes), including events with and without visual distraction among drivers of cars, heavy trucks, and buses. A simple piecewise linear model could be successfully fitted, per event, to the observed driver decelerations, allowing a detailed elucidation of when drivers initiated braking and how they controlled it. Most notably, it was found that, across vehicle types, driver braking behavior was strongly dependent on the urgency of the given rear-end scenario's kinematics, quantified in terms of visual looming of the lead vehicle on the driver's retina. In contrast with previous suggestions of brake reaction times (BRTs) of 1.5s or more after onset of an unexpected hazard (e.g., brake light onset), it was found here that braking could be described as typically starting less than a second after the kinematic urgency reached certain threshold levels, with even faster reactions at higher urgencies. The rate at which drivers then increased their deceleration (towards a maximum) was also highly dependent on urgency. Probability distributions are provided that quantitatively capture these various patterns of kinematics-dependent behavioral response. Possible underlying mechanisms are suggested, including looming response thresholds and neural evidence accumulation. These accounts argue that a naturalistic braking response should not be thought of as a slow reaction to some single, researcher-defined "hazard onset", but instead as a relatively fast response to the visual looming cues that build up later on in the evolving traffic scenario.

  5. White matter integrity and reaction time intraindividual variability in healthy aging and early-stage Alzheimer disease.

    PubMed

    Jackson, Jonathan D; Balota, David A; Duchek, Janet M; Head, Denise

    2012-02-01

    Aging and early-stage Alzheimer disease (AD) have been shown to be associated with increased RT intraindividual variability (IIV, as reflected by the coefficient of variation) and an exaggeration of the slow tail of the reaction time (RT) distribution in attentional control tasks, based on ex-Gaussian analyses. The current study examined associations between white matter volume, IIV, and ex-Gaussian RT distribution parameters in cognitively normal aging and early-stage AD. Three RT attention tasks (Stroop, Simon, and a consonant-vowel odd-even switching task) in conjunction with MRI-based measures of cerebral and regional white matter volume were obtained in 133 cognitively normal and 33 early-stage AD individuals. Larger volumes were associated with less IIV and less slowing in the tail of the RT distribution, and larger cerebral and inferior parietal white matter volumes were associated with faster modal reaction time. Collectively, these results support a role of white matter integrity in IIV and distributional skewing, and are consistent with the hypothesis that IIV and RT distributional skewing are sensitive to breakdowns in executive control processes in normal and pathological aging.

  6. Effect on the parameters of the high-heel shoe and transfer time of ground reaction force during level walking

    PubMed Central

    Hyun, Seung-Hyun; Kim, Young-Pyo; Ryew, Che-Cheong

    2016-01-01

    This study aimed to analyze an effect on the parameters of high-heel shoe and transfer time of ground reaction force during level walking and subjects participated were composed of adult female subjects (n=13) of 20s with height of high heel (0 cm, 9 cm, respectively). Instrument used for the study was 1 set force plate (AMTI-OR9-7) and sampling rate for data collection of analysis parameters was set-up at 1,000 Hz. The revelation of required coefficient of friction (RCOF) maximum showed significant difference with more rapid than that of 1st peak vertical force (1 PVF). Transfer time of body weight showed significant difference with more delay at 9 cm than that of 0 cm. RCOF required more frictional force required because PVF showed significant difference with larger value on 9 cm than that of 3 cm at 1 PVF. Both center of pressure (COP) x and COPy showed rather less displacement on 9 cm than that of 0 cm. In addition, level walking by high heel shoe did not control efficiently the ground reaction force due to restricted control capacity of coefficient of frictional force and therefore could suggest an inducement of muscle fatigue, heightening a possibility of sliding and falling due to decrease of frictional force. PMID:27807524

  7. Real-Time Fluorescent Polymerase Chain Reaction Detection of Phytophthora ramorum and Phytophthora pseudosyringae Using Mitochondrial Gene Regions.

    PubMed

    Tooley, Paul W; Martin, Frank N; Carras, Marie M; Frederick, Reid D

    2006-04-01

    ABSTRACT A real-time fluorescent polymerase chain reaction (PCR) detection method for the sudden oak death pathogen Phytophthora ramorum was developed based on mitochondrial DNA sequence with an ABI Prism 7700 (TaqMan) Sequence Detection System. Primers and probes were also developed for detecting P. pseudosyringae, a newly described species that causes symptoms similar to P. ramorum on certain hosts. The species-specific primer-probe systems were combined in a multiplex assay with a plant primer-probe system to allow plant DNA present in extracted samples to serve as a positive control in each reaction. The lower limit of detection of P. ramorum DNA was 1 fg of genomic DNA, lower than for many other described PCR procedures for detecting Phytophthora species. The assay was also used in a three-way multiplex format to simultaneously detect P. ramorum, P. pseudosyringae, and plant DNA in a single tube. P. ramorum was detected down to a 10(-5) dilution of extracted tissue of artificially infected rhododendron 'Cunningham's White', and the amount of pathogen DNA present in the infected tissue was estimated using a standard curve. The multiplex assay was also used to detect P. ramorum in infected California field samples from several hosts determined to contain the pathogen by other methods. The real-time PCR assay we describe is highly sensitive and specific, and has several advantages over conventional PCR assays used for P. ramorum detection to confirm positive P. ramorum finds in nurseries and elsewhere.

  8. Time scale of hydrothermal water-rock reactions in Yellowstone National Park based on radium isotopes and radon

    NASA Astrophysics Data System (ADS)

    Clark, Jordan F.; Turekian, Karl K.

    1990-02-01

    We have measured 224Ra (3.4 d), 228Ra (5.7 yr), and 226Ra (1620 yr) and chloride in hot spring waters from the Norris-Mammoth Corridor, Yellowstone National Park. Two characteristic cold-water components mix with the primary hydrothermal water: one for the travertine-depositing waters related to the Mammoth Hot Springs and the other for the sinter-depositing Norris Geyser Basin springs. The Mammoth Hot Springs water is a mixture of the primary hydrothermal fluid with meteoric waters flowing through the Madison Limestone, as shown by the systematic decrease of the ( {228Ra}/{226Ra}) activity ratio proceeding northward. The Norris Geyser Basin springs are mixtures of primary hydrothermal water with different amounts of cold meteoric water with no modification of the primary hydrothermal ( {228Ra}/{226Ra}) activity ratio. Using a solution and recoil model for radium isotope supply to the primary hydrothermal water, a mean water-rock reaction time prior to expansion at 350°C and supply to the surface is 540 years assuming that 250 g of water are involved in the release of the radium from one gram of rock. The maximum reaction time allowed by our model is 1150 years.

  9. Prepotent response inhibition and reaction times in children with attention deficit/hyperactivity disorder from a Caribbean community.

    PubMed

    Jiménez-Figueroa, Giomar; Ardila-Duarte, Carlos; Pineda, David A; Acosta-López, Johan E; Cervantes-Henríquez, Martha L; Pineda-Alhucema, Wilmar; Cervantes-Gutiérrez, Jeimys; Quintero-Ibarra, Marisol; Sánchez-Rojas, Manuel; Vélez, Jorge I; Puentes-Rozo, Pedro J

    2017-02-25

    Impairment in inhibitory control has been postulated as an underlying hallmark of attention deficit/hyperactivity disorder (ADHD), which can be utilized as a quantitative trait for genetic studies. Here, we evaluate whether inhibitory control, measured by simple automatized prepotent response (PR) inhibition variables, is a robust discriminant function for the diagnosis of ADHD in children and can be used as an endophenotype for future genetic studies. One hundred fifty-two school children (30.9% female, 67.8% with ADHD) were recruited. The ADHD checklist was used as the screening tool, whilst the DSM-IV Mini International Neuropsychiatry Interview, neurologic interview and neurologic examination, and the WISC III FSIQ test were administered as the gold standard procedure to assert ADHD diagnosis. A Go/No-Go task using a naturalistic and automatized visual signal was administered. A linear multifactor model (MANOVA) was fitted to compare groups including ADHD status, age, and gender as multiple independent factors. Linear discriminant analysis and the receiver operating characteristic curve were used to assess the predictive performance of PR inhibition variables for ADHD diagnosis. We found that four variables of prepotent response reaction time- and prepotent response inhibition established statistically significant differences between children with and without ADHD. Furthermore, these variables generated a strong discriminant function with a total classification capability of 73, 84% specificity, 68% sensitivity, and 90% positive predictive value for ADHD diagnosis, which support reaction times as a candidate endophenotype that could potentially be used in future ADHD genetic research.

  10. Simulation of reaction diffusion processes over biologically relevant size and time scales using multi-GPU workstations.

    PubMed

    Hallock, Michael J; Stone, John E; Roberts, Elijah; Fry, Corey; Luthey-Schulten, Zaida

    2014-05-01

    Simulation of in vivo cellular processes with the reaction-diffusion master equation (RDME) is a computationally expensive task. Our previous software enabled simulation of inhomogeneous biochemical systems for small bacteria over long time scales using the MPD-RDME method on a single GPU. Simulations of larger eukaryotic systems exceed the on-board memory capacity of individual GPUs, and long time simulations of modest-sized cells such as yeast are impractical on a single GPU. We present a new multi-GPU parallel implementation of the MPD-RDME method based on a spatial decomposition approach that supports dynamic load balancing for workstations containing GPUs of varying performance and memory capacity. We take advantage of high-performance features of CUDA for peer-to-peer GPU memory transfers and evaluate the performance of our algorithms on state-of-the-art GPU devices. We present parallel e ciency and performance results for simulations using multiple GPUs as system size, particle counts, and number of reactions grow. We also demonstrate multi-GPU performance in simulations of the Min protein system in E. coli. Moreover, our multi-GPU decomposition and load balancing approach can be generalized to other lattice-based problems.

  11. Simulation of reaction diffusion processes over biologically relevant size and time scales using multi-GPU workstations

    PubMed Central

    Hallock, Michael J.; Stone, John E.; Roberts, Elijah; Fry, Corey; Luthey-Schulten, Zaida

    2014-01-01

    Simulation of in vivo cellular processes with the reaction-diffusion master equation (RDME) is a computationally expensive task. Our previous software enabled simulation of inhomogeneous biochemical systems for small bacteria over long time scales using the MPD-RDME method on a single GPU. Simulations of larger eukaryotic systems exceed the on-board memory capacity of individual GPUs, and long time simulations of modest-sized cells such as yeast are impractical on a single GPU. We present a new multi-GPU parallel implementation of the MPD-RDME method based on a spatial decomposition approach that supports dynamic load balancing for workstations containing GPUs of varying performance and memory capacity. We take advantage of high-performance features of CUDA for peer-to-peer GPU memory transfers and evaluate the performance of our algorithms on state-of-the-art GPU devices. We present parallel e ciency and performance results for simulations using multiple GPUs as system size, particle counts, and number of reactions grow. We also demonstrate multi-GPU performance in simulations of the Min protein system in E. coli. Moreover, our multi-GPU decomposition and load balancing approach can be generalized to other lattice-based problems. PMID:24882911

  12. Event-related potentials, reaction time, and response selection of skilled and less-skilled cricket batsmen.

    PubMed

    Sharhidd Taliep, M; St Clair Gibson, A; Gray, J; van der Merwe, L; Vaughan, C L; Noakes, T D; Kellaway, L A; John, L R

    2008-01-01

    The differences in P300 latency, P300 amplitude, response selection, and reaction time between skilled and less-skilled cricket batsmen have been investigated. Eight skilled and ten less-skilled right-handed batsmen each viewed 100 in-swing, 100 out-swing, and 40 slower deliveries displayed in random sequence from projected video footage whilst their responses and electroencephalograms were recorded. Logistic regression was used to derive a discriminative function for the P300 data. This was done to determine whether the skilled batsmen differed from the less-skilled batsmen on the basis of pooled P300 amplitude and latency data. All the batsmen were correctly characterised as being skilled or less-skilled. Logistic regression equations with reaction time and correctness of response data indicated that behavioural data do not correctly classify skilled performance. It is suggested that skilled cricket batsmen have a superior perceptual decision-making ability compared with less-skilled cricket batsmen, as measured by P300 latency and amplitude. This appears to be the first study showing a link between skill and cerebral cortical activity during a perceptual cricket batting task and it could pave the way for future studies on mental processing in cricket batsmen.

  13. Fast-neutron Induced Reactions at the nELBE Time-of-flight Facility

    NASA Astrophysics Data System (ADS)

    Junghans, A. R.; Beyer, R.; Elekes, Z.; Grosse, E.; Hannaske, R.; Kögler, T.; Massarczyk, R.; Schwengner, R.; Wagner, A.

    2014-05-01

    The compact neutron-time-of-flight facility nELBE at the superconducting electron accelerator ELBE of Helmholtz-Zentrum Dresden-Rossendorf is being rebuilt and extended with a low-background experimental hall. The neutron radiator consists of a liquid lead circuit without additional neutron moderators. The useful neutron spectrum extends from some tens of keV to about 10 MeV. nELBE is intended to deliver cross section data of fast-neutron nuclear interactions e.g. for the transmutation of nuclear waste and improvement of neutron physical simulations of innovative nuclear systems. Before the extension of the facility, the photon production cross section of 56Fe was measured with an HPGe detector and the inelastic neutron scattering cross section to the first few excited states in 56Fe was determined. The neutron total cross sections of Au and Ta were determined in the energy from 200 keV to 7 MeV in a transmission experiment.

  14. Virtual Hand Feedback Reduces Reaction Time in an Interactive Finger Reaching Task

    PubMed Central

    Brand, Johannes; Piccirelli, Marco; Hepp-Reymond, Marie-Claude; Morari, Manfred

    2016-01-01

    Computer interaction via visually guided hand or finger movements is a ubiquitous part of daily computer usage in work or gaming. Surprisingly, however, little is known about the performance effects of using virtual limb representations versus simpler cursors. In this study 26 healthy right-handed adults performed cued index finger flexion-extension movements towards an on-screen target while wearing a data glove. They received each of four different types of real-time visual feedback: a simple circular cursor, a point light pattern indicating finger joint positions, a cartoon hand and a fully shaded virtual hand. We found that participants initiated the movements faster when receiving feedback in the form of a hand than when receiving circular cursor or point light feedback. This overall difference was robust for three out of four hand versus circle pairwise comparisons. The faster movement initiation for hand feedback was accompanied by a larger movement amplitude and a larger movement error. We suggest that the observed effect may be related to priming of hand information during action perception and execution affecting motor planning and execution. The results may have applications in the use of body representations in virtual reality applications. PMID:27144927

  15. Clinical validation of a real-time polymerase chain reaction assay for rapid detection of Acinetobacter baumannii colonization.

    PubMed

    Blanco-Lobo, P; González-Galán, V; García-Quintanilla, M; Valencia, R; Cazalla, A; Martín, C; Alonso, I; Pérez-Romero, P; Cisneros, J M; Aznar, J; McConnell, M J

    2016-09-01

    Real-time polymerase chain reaction (PCR)-based approaches have not been assessed in terms of their ability to detect patients colonized by Acinetobacter baumannii during active surveillance. This prospective, double-blind study demonstrated that a real-time PCR assay had high sensitivity (100%) and specificity (91.2%) compared with conventional culture for detecting A. baumannii in 397 active surveillance samples, and provided results within 3h. Receiver-operator curve analyses demonstrated that the technique has diagnostic accuracy of 97.7% (95% confidence interval 96.0-99.3%). This method could facilitate the rapid implementation of infection control measures for preventing the transmission of A. baumannii.

  16. Reaction time analysis of two types of motor preparation for speech articulation: action as a sequence of chunks.

    PubMed

    Klapp, Stuart T

    2003-06-01

    Reaction time (RT) prior to speech articulation increased as a function of response complexity. The RT findings formed 2 patterns, each of which was a different Response Complexity x Paradigm (choice RT vs. simple RT) interaction. That result extends previous findings from manual button-pressing tasks (S. T. Klapp, 1995) to a different action modality. Two different types of response programming, INT and SEQ, are assumed in the interpretation. Whereas INT can be identified with response programming within a word, SEQ fits a different interpretation related to timing of onsets of speech units. A critical assumption is that a long response is represented as a sequence of chunks; that organization is subject to manipulation. New findings suggest some modifications of the previous theory.

  17. Space-time least-squares finite element method for convection-reaction system with transformed variables

    PubMed Central

    Nam, Jaewook

    2011-01-01

    We present a method to solve a convection-reaction system based on a least-squares finite element method (LSFEM). For steady-state computations, issues related to recirculation flow are stated and demonstrated with a simple example. The method can compute concentration profiles in open flow even when the generation term is small. This is the case for estimating hemolysis in bloo