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Sample records for single stimulus sample

  1. Sample Stimulus Control Shaping and Restricted Stimulus Control in Capuchin Monkeys: A Methodological Note

    Science.gov (United States)

    Brino, Ana Leda F., Barros, Romariz S., Galvao, Ol; Garotti, M.; Da Cruz, Ilara R. N.; Santos, Jose R.; Dube, William V.; McIlvane, William J.

    2011-01-01

    This paper reports use of sample stimulus control shaping procedures to teach arbitrary matching-to-sample to 2 capuchin monkeys ("Cebus apella"). The procedures started with identity matching-to-sample. During shaping, stimulus features of the sample were altered gradually, rendering samples and comparisons increasingly physically dissimilar. The…

  2. Stimulus-response functions of single avian olfactory bulb neurones.

    Science.gov (United States)

    McKeegan, Dorothy E F; Demmers, Theodorus G M; Wathes, Christopher M; Jones, R Bryan; Gentle, Michael J

    2002-10-25

    This study investigated olfactory processing in a functional context by examining the responses of single avian olfactory bulb neurones to two biologically important gases over relevant concentration ranges. Recordings of extracellular spike activity were made from 80 single units in the left olfactory bulb of 11 anaesthetised, freely breathing adult hens (Gallus domesticus). The units were spontaneously active, exhibiting widely variable firing rates (0.07-47.28 spikes/s) and variable temporal firing patterns. Single units were tested for their response to an ascending concentration series of either ammonia (2.5-100 ppm) or hydrogen sulphide (1-50 ppm), delivered directly to the olfactory epithelium. Stimulation with a calibrated gas delivery system resulted in modification of spontaneous activity causing either inhibition (47% of units) or excitation (53%) of firing. For ammonia, 20 of the 35 units tested exhibited a response, while for hydrogen sulphide, 25 of the 45 units tested were responsive. Approximate response thresholds for ammonia (median threshold 3.75 ppm (range 2.5-60 ppm, n=20)) and hydrogen sulphide (median threshold 1 ppm (range 1-10 ppm, n=25)) were determined with most units exhibiting thresholds near the lower end of these ranges. Stimulus response curves were constructed for 23 units; 16 (the most complete) were subjected to a linear regression analysis to determine whether they were best fitted by a linear, log or power function. No single function provided the best fit for all the curves (seven were linear, eight were log, one was power). These findings show that avian units respond to changes in stimulus concentration in a manner generally consistent with reported responses in mammalian olfactory bulb neurones. However, this study illustrates a level of fine-tuning to small step changes in concentration (<5 ppm) not previously demonstrated in vertebrate single olfactory bulb neurones.

  3. Space and Motion Stimulus-Response Correspondence (SRC) Effects in a Single Task.

    Science.gov (United States)

    Styrkowiec, Piotr

    2016-09-01

    Previous research indicated that congruency between stimulus location and response position (spatial stimulus-response correspondence [SRC]) and stimulus motion and response movement congruency (motion SRC) are distinct SRC phenomena. This study further explored this issue and tested whether these two SRC effects are independent. This was conducted by investigating these two SRC effects in a single task. A stimulus with leftward or rightward motion was presented on the left or the right side of the screen and the participant had to move the joysticks held with the left and right hands leftward or rightward in response to the stimulus color. In this setting, the stimulus and response shared two types of correspondence: spatial and motion. The results demonstrated that two SRC effects occurred and interacted (interaction evident only in reaction times [RTs]). RT distribution analysis and accuracy delta plots for each SRC effect indicated that spatial and motion SRC are distinct phenomena based on different processes.

  4. Single-Trial Linear Correlation Analysis: Application to characterization of stimulus modality effects

    Directory of Open Access Journals (Sweden)

    Christoforos eChristoforou

    2013-03-01

    Full Text Available A key objective in systems and cognitive neuroscience is to establish associations between behavioral measures and concurrent neuronal activity. Single-trial analysis has been proposed as a novel method for characterizing such correlates by first extracting neural components that maximally discriminate trials on a categorical variable, (e.g., hard vs. easy, correct vs. incorrect etc., and then correlate those components to a continues dependent variable of interest , e.g. reaction time, difficulty Index, etc. However, often times in experiment design it is difficult to either define meaningful categorical variables, or to record enough trials for the method to extract the discriminant components. Experiments designed for the study of the effects of stimulus presentation modality in working memory provide such a scenario, as will be exemplified. In this paper, we proposed a new approach to single-trial analysis in which we directly extract neural activity that maximally correlates to single-trial manual response times; eliminating the need to define an arbitrary categorical variable. We demonstrate our method on real EEG data recordings from the study of stimulus presentation modality effect.

  5. The effects of stimulus modality and task integrality: Predicting dual-task performance and workload from single-task levels

    Science.gov (United States)

    Hart, S. G.; Shively, R. J.; Vidulich, M. A.; Miller, R. C.

    1986-01-01

    The influence of stimulus modality and task difficulty on workload and performance was investigated. The goal was to quantify the cost (in terms of response time and experienced workload) incurred when essentially serial task components shared common elements (e.g., the response to one initiated the other) which could be accomplished in parallel. The experimental tasks were based on the Fittsberg paradigm; the solution to a SternBERG-type memory task determines which of two identical FITTS targets are acquired. Previous research suggested that such functionally integrated dual tasks are performed with substantially less workload and faster response times than would be predicted by suming single-task components when both are presented in the same stimulus modality (visual). The physical integration of task elements was varied (although their functional relationship remained the same) to determine whether dual-task facilitation would persist if task components were presented in different sensory modalities. Again, it was found that the cost of performing the two-stage task was considerably less than the sum of component single-task levels when both were presented visually. Less facilitation was found when task elements were presented in different sensory modalities. These results suggest the importance of distinguishing between concurrent tasks that complete for limited resources from those that beneficially share common resources when selecting the stimulus modalities for information displays.

  6. An evaluation of the stimulus equivalence paradigm to teach single-subject design to distance education students via Blackboard.

    Science.gov (United States)

    Walker, Brooke D; Rehfeldt, Ruth Anne

    2012-01-01

    The purpose of the current study was to examine the degree to which instruction based on stimulus equivalence procedures could be used to teach single-subject design methodology to graduate-level professionals through a Web-based course management system known as Blackboard (see http://www.blackboard.com). Specifically, we used the stimulus equivalence paradigm to teach relations among the names, definitions, graphical representations of the designs, and two practical scenarios of when it would be appropriate to implement each design. Most participants demonstrated the emergence of untaught relations, and some participants showed generalization to novel vignettes and graphs. Relations largely were not maintained at follow-up but were retaught.

  7. Intertrial Sources of Stimulus Control and Delayed Matching-to-Sample Performance in Humans

    Science.gov (United States)

    Williams, Dean C.; Johnston, Mark D.; Saunders, Kathryn J.

    2006-01-01

    Two experiments compared delayed matching-to-sample (DMTS) accuracy under 2 procedures in adults with mental retardation. In the trial-unique procedure, every trial in a session contained different stimuli. Thus, comparison stimuli that were correct on one trial were never incorrect on other trials in that session (or vice versa). In the 2-sample…

  8. Effect of Familiar Olfactory Stimulus on Responses to Blood Sampling Pain in Neonates

    Directory of Open Access Journals (Sweden)

    A. Sadathosseini

    2011-04-01

    Full Text Available Introduction & Objective: Pain in neonates can lead to various risks. So, it seems essential to find a simple, safe, and acceptable method for relieving pain. The objective of this study was to assess the effectiveness of olfactory stimuli (familiar and unfamiliar on physiological and behavioral responses to the pain of arterial blood draws in term neonates. Materials & Methods: In this quasi-experimental clinical trial, according to the conditions of the study 135 term neonates were chosen by convenience sampling and were assigned to three groups. During the procedure, familiar odor group was presented with the vanilla smell with which they had been familiarized prior to the procedure for 9 hours. Unfamiliar odor group was presented with the vanilla smell to which they had not been previously exposed, and the control group was presented with no odor. The heart rate and O2 saturation levels were measured before, after inserting and after removing the needle. Also, their cry duration was measured from onset until a crying free interval of more than five seconds. Results: The infants exposed to the familiar odor cried significantly less during the procedure compared to the unfamiliar odor and no odor group (P<0.001. Moreover, there was no statistically significant difference in the heart rate among the groups after inserting and removing the needle and in the O2 saturation rate after inserting the needle. The O2 saturation rate was significantly higher in the familiar odor group compared with the other groups (p<0.05 after the needle removal. Conclusion: A familiar odor is effective in reducing crying during arterial blood draws in neonates, but does not affect on physiological parameters. (Sci J Hamadan Univ Med Sci 2011;18(1:10-19

  9. a comparison between the use of single and composite samples

    African Journals Online (AJOL)

    Dr F Neser

    A comparison between single and composite milk samples for the genetic evaluation of milk composition in dairy cattle ... Dairy Cattle Performance Testing Scheme replaced composite sampling with a single sample in 1995. The implementation of the new Scheme was ... Materials and methods. To obtain information on the ...

  10. A single-sampling hair trap for mesocarnivores

    Science.gov (United States)

    Jonathan N. Pauli; Matthew B. Hamilton; Edward B. Crain; Steven W. Buskirk

    2007-01-01

    Although techniques to analyze and quantifY DNA-based data have progressed, methods to noninvasively collect samples lag behind. Samples are generally collected from devices that permit coincident sampling of multiple individuals. Because of cross-contamination, substantive genotyping errors can arise. We developed a cost-effective (US$4.60/trap) single-capture hair...

  11. Single versus duplicate blood samples in ACTH stimulated adrenal vein sampling

    NARCIS (Netherlands)

    Dekkers, T.; Arntz, M.; Wilt, G.J. van der; Schultze Kool, L.J.; Sweep, F.C.; Hermus, A.R.M.M.; Lenders, J.W.M.; Deinum, J.

    2013-01-01

    BACKGROUND: Adrenal vein sampling (AVS) is the preferred test for subtyping primary aldosteronism. However, the procedure is technically demanding and costly. In AVS it is common practice to take duplicate blood samples at each location. In this paper we explore whether a single sample procedure

  12. a comparison between the use of single and composite samples

    African Journals Online (AJOL)

    Dr F Neser

    South African Society for Animal Science. 44. A comparison between single and composite milk samples for the genetic evaluation of milk composition in dairy cattle. R. van Dyk1, F.W.C. Neser1# & F.H. Kanfer2. 1 Department of Animal Science, University of the Free State, PO Box 339, Bloemfontein 9300, South Africa.

  13. Genomic Sequencing of Single Microbial Cells from Environmental Samples

    Energy Technology Data Exchange (ETDEWEB)

    Ishoey, Thomas; Woyke, Tanja; Stepanauskas, Ramunas; Novotny, Mark; Lasken, Roger S.

    2008-02-01

    Recently developed techniques allow genomic DNA sequencing from single microbial cells [Lasken RS: Single-cell genomic sequencing using multiple displacement amplification, Curr Opin Microbiol 2007, 10:510-516]. Here, we focus on research strategies for putting these methods into practice in the laboratory setting. An immediate consequence of single-cell sequencing is that it provides an alternative to culturing organisms as a prerequisite for genomic sequencing. The microgram amounts of DNA required as template are amplified from a single bacterium by a method called multiple displacement amplification (MDA) avoiding the need to grow cells. The ability to sequence DNA from individual cells will likely have an immense impact on microbiology considering the vast numbers of novel organisms, which have been inaccessible unless culture-independent methods could be used. However, special approaches have been necessary to work with amplified DNA. MDA may not recover the entire genome from the single copy present in most bacteria. Also, some sequence rearrangements can occur during the DNA amplification reaction. Over the past two years many research groups have begun to use MDA, and some practical approaches to single-cell sequencing have been developed. We review the consensus that is emerging on optimum methods, reliability of amplified template, and the proper interpretation of 'composite' genomes which result from the necessity of combining data from several single-cell MDA reactions in order to complete the assembly. Preferred laboratory methods are considered on the basis of experience at several large sequencing centers where >70% of genomes are now often recovered from single cells. Methods are reviewed for preparation of bacterial fractions from environmental samples, single-cell isolation, DNA amplification by MDA, and DNA sequencing.

  14. Using (10)CO2 for single subject characterization of the stimulus frequency dependence in visual cortex: a novel positron emission tomography tracer for human brain mapping.

    Science.gov (United States)

    Law, I; Jensen, M; Holm, S; Nickles, R J; Paulson, O B

    2001-08-01

    Carbon-10-labeled carbon dioxide ((10)CO2) with a half-life of 19.3 seconds offers almost ideal characteristics as a positron emission tomography (PET) tracer for assessment of the regional cerebral blood flow (rCBF) distribution, enabling multiple independent measurements at short intervals. To appraise the feasibility of (10)CO2 for localizing and characterizing human brain function in single subjects, the authors chose a well-characterized activation paradigm. In 6 healthy volunteers, 50 to 64 independent PET scans of the rCBF distribution were acquired while viewing an annular reversing checkerboard presented at 10 reversal frequencies between 0.03 and 30 Hz. Changes in regional cerebral activity as a function of reversal frequency were modeled in every subject using a set of polynomial basis functions, which, as predicted, showed highly significant second or third order relations located in the striatal cortex. Correlation coefficients (R2) ranged from 0.46 to 0.63. The average intersubject maximal response relative to the 0.03 Hz condition was 8.0% +/- 1.7% SD occurring at stimulus contrast reversal frequencies between 6 and 15 Hz with an average of 11.8 +/- 3.8 (SD) Hz. From the qualitative and quantitative replication of previous results it is concluded that (10)CO2 PET is a feasible technique for human brain mapping studies and a great improvement compared with the existing oxygen-15-labeled water (H(2)(15)O) PET method, particularly for single subject studies and parametric design.

  15. A Single Platinum Microelectrode for Identifying Soft Drink Samples

    Directory of Open Access Journals (Sweden)

    Lígia Bueno

    2012-01-01

    Full Text Available Cyclic voltammograms recorded with a single platinum microelectrode were used along with a non-supervised pattern recognition, namely, Principal Component Analysis, to conduct a qualitative analysis of sixteen different brands of carbonated soft drinks (Kuat, Soda Antarctica, H2OH!, Sprite 2.0, Guarana Antarctica, Guarana Antarctica Zero, Coca-Cola, Coca-Cola Zero, Coca-Cola Plus, Pepsi, Pepsi Light, Pepsi Twist, Pepsi Twist Light, Pepsi Twist 3, Schin Cola, and Classic Dillar’s. In this analysis, soft drink samples were not subjected to pre-treatment. Good differentiation among all the analysed soft drinks was achieved using the voltammetric data. An analysis of the loading plots shows that the potentials of −0.65 V, −0.4 V, 0.4 V, and 0.750 V facilitated the discrimination process. The electrochemical processes related to this potential are the reduction of hydrogen ions and inhibition of the platinum oxidation by the caffeine adsorption on the electrode surface. Additionally, the single platinum microelectrode was useful for the quality control of the soft drink samples, as it helped to identify the time at which the beverage was opened.

  16. Single-stage mass spectrometric analyses of resin bead samples

    Energy Technology Data Exchange (ETDEWEB)

    Smith, D. H.; Walker, R. L.; Bertram, L. K.; Carter, J. A.

    1978-10-01

    Plutonium and uranium from dissolver solutions loaded on resin beads can be analyzed on single-stage mass spectrometers with little or no degradation of results provided proper care is exercised with regard to sample handling techniques. Additionally, storage of samples on resin beads is feasible for periods at least as long as six months provided the beads are not exposed to residual HNO/sub 3/ and air; it is probable that beads will retain their integrity much longer than six months when stored under collodion, but as yet no data to support this contention have been collected. Conventional or commercial mass spectrometers can readily be adapted to the resin bead technique by installing a pulse-counting detection system. The cost of such conversion will vary depending on whether or not a data acquisition system will be needed. A reasonable estimate is that the cost will be in the neighborhood of $15,000; this figure includes the price of a multi-channel analyzer to serve as a temporary data storage device, but does not include the cost of a computer. It does not appear that it will be practicable to switch easily back and forth between pulse-counting and current integration modes unless the instrument is provided with a movable Faraday cup. Using the same multiplier in both modes would undoubtedly degrade its performance in each. The requirements of low background counting rates and high gain for pulse counting, and of relatively high signal handling capacity in current integration are mutually incompatible if demanded of the same multiplier.

  17. Stimulus-dependent maximum entropy models of neural population codes.

    Directory of Open Access Journals (Sweden)

    Einat Granot-Atedgi

    Full Text Available Neural populations encode information about their stimulus in a collective fashion, by joint activity patterns of spiking and silence. A full account of this mapping from stimulus to neural activity is given by the conditional probability distribution over neural codewords given the sensory input. For large populations, direct sampling of these distributions is impossible, and so we must rely on constructing appropriate models. We show here that in a population of 100 retinal ganglion cells in the salamander retina responding to temporal white-noise stimuli, dependencies between cells play an important encoding role. We introduce the stimulus-dependent maximum entropy (SDME model-a minimal extension of the canonical linear-nonlinear model of a single neuron, to a pairwise-coupled neural population. We find that the SDME model gives a more accurate account of single cell responses and in particular significantly outperforms uncoupled models in reproducing the distributions of population codewords emitted in response to a stimulus. We show how the SDME model, in conjunction with static maximum entropy models of population vocabulary, can be used to estimate information-theoretic quantities like average surprise and information transmission in a neural population.

  18. Development of a Single-Sampling Noninvasive Hair Snare

    DEFF Research Database (Denmark)

    Bremner-Harrison, Samantha; Harrison, Stephen W. R.; Cypher, Brian L.

    2006-01-01

    Noninvasive hair and fecal DNA sampling provides a means of collecting information on elusive species, while causing little or no disturbance. However, current methods of hair collection do not preclude multiple sampling, thus risking sample contamination. We developed a hair snare that prevents ...

  19. Directional emission of single photons from small atomic samples

    DEFF Research Database (Denmark)

    Miroshnychenko, Yevhen; V. Poulsen, Uffe; Mølmer, Klaus

    2013-01-01

    We provide a formalism to describe deterministic emission of single photons with tailored spatial and temporal profiles from a regular array of multi-level atoms. We assume that a single collective excitation is initially shared by all the atoms in a metastable atomic state, and that this state i...... is coupled by a classical laser field to an optically excited state which rapidly decays to the ground atomic state. Our model accounts for the different field polarization components via re-absorption and emission of light by the Zeeman manifold of optically excited states.......We provide a formalism to describe deterministic emission of single photons with tailored spatial and temporal profiles from a regular array of multi-level atoms. We assume that a single collective excitation is initially shared by all the atoms in a metastable atomic state, and that this state...

  20. Development of a Single-Sampling Noninvasive Hair Snare

    DEFF Research Database (Denmark)

    Bremner-Harrison, Samantha; Harrison, Stephen W. R.; Cypher, Brian L.

    2006-01-01

    Noninvasive hair and fecal DNA sampling provides a means of collecting information on elusive species, while causing little or no disturbance. However, current methods of hair collection do not preclude multiple sampling, thus risking sample contamination. We developed a hair snare that prevents...... multiple sampling, is cost-effective, easy to construct, and safe for target and nontarget species. Our initial field tests on endangered San Joaquin kit foxes (Vulpes macrotis mutica) and swift foxes (Vulpes velox) suggest that this hair snare may be effective in collecting uncontaminated samples for DNA...

  1. Reliable single cell array CGH for clinical samples.

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    Zbigniew T Czyż

    Full Text Available BACKGROUND: Disseminated cancer cells (DCCs and circulating tumor cells (CTCs are extremely rare, but comprise the precursors cells of distant metastases or therapy resistant cells. The detailed molecular analysis of these cells may help to identify key events of cancer cell dissemination, metastatic colony formation and systemic therapy escape. METHODOLOGY/PRINCIPAL FINDINGS: Using the Ampli1™ whole genome amplification (WGA technology and high-resolution oligonucleotide aCGH microarrays we optimized conditions for the analysis of structural copy number changes. The protocol presented here enables reliable detection of numerical genomic alterations as small as 0.1 Mb in a single cell. Analysis of single cells from well-characterized cell lines and single normal cells confirmed the stringent quantitative nature of the amplification and hybridization protocol. Importantly, fixation and staining procedures used to detect DCCs showed no significant impact on the outcome of the analysis, proving the clinical usability of our method. In a proof-of-principle study we tracked the chromosomal changes of single DCCs over a full course of high-dose chemotherapy treatment by isolating and analyzing DCCs of an individual breast cancer patient at four different time points. CONCLUSIONS/SIGNIFICANCE: The protocol enables detailed genome analysis of DCCs and thereby assessment of the clonal evolution during the natural course of the disease and under selection pressures. The results from an exemplary patient provide evidence that DCCs surviving selective therapeutic conditions may be recruited from a pool of genomically less advanced cells, which display a stable subset of specific genomic alterations.

  2. Vapor and gas sampling of single-shell tank 241-U-104 using the in situ vapor sampling system

    International Nuclear Information System (INIS)

    Lockrem, L.L.

    1997-01-01

    The Vapor Issue.Resolution Program tasked the Vapor Team (VT) to collect representative headspace samples from Hanford Site single-shell tank (SST) 241-U-104. This document presents In Situ Vapor Sampling System (ISVS) data resulting from the July 16, 1996 sampling of SST 241-U-104. Analytical results will be presented in separate reports issued by the Pacific Northwest National Laboratory (PNNL) which supplied and analyzed the sample media

  3. Vapor and gas sampling of single-shell tank 241-BX-110 using the in situ vapor sampling system

    International Nuclear Information System (INIS)

    Lockrem, L.L.

    1997-01-01

    The Vapor Issue Resolution Program tasked the Vapor Team (the team) to collect representative headspace samples from Hanford Site single-shell tank (SST) 241-BX-110. This document presents sampling data resulting from the April 30, 1996 sampling of SST 241-BX-110. Analytical results will be presented in a separate report issued by Pacific Northwest National Laboratory (PNNL), which supplied and analyzed the sampling media

  4. Vapor and gas sampling of single-shell tank 241-S-106 using the in situ vapor sampling system

    International Nuclear Information System (INIS)

    Lockrem, L.L.

    1997-01-01

    The Vapor Issue Resolution Program tasked the Vapor Team (VT) to collect representative headspace samples from Hanford Site single-shell tank (SST) 241-S-106. This document presents In Situ vapor Sampling System (ISVS) data resulting from the June 13, 1996 sampling of SST 241-S-106. Analytical results will be presented in separate reports issued by the Pacific Northwest National Laboratory (PNNL) which'supplied and analyzed the sample media

  5. Vapor and gas sampling of single-shell tank 241-S-103 using the in situ vapor sampling system

    International Nuclear Information System (INIS)

    Lockrem, L.L.

    1997-01-01

    The Vapor Issue Resolution Program tasked the Vapor Team (VT) to collect representative headspace samples from Hanford Site single-shell tank (SST) 241-S-103. This document presents In Situ Vapor Sampling System (ISVS) data resulting from the June 12, 1996 sampling of SST 241-S-103. Analytical results will be presented in separate reports issued by the Pacific Northwest National Laboratory (PNNL) which supplied and analyzed the sample media

  6. Equivalência de estímulos após treino de pareamento consistente de estímulos com atraso do modelo Stimulus equivalence after consistent delayed matching-to-sample

    Directory of Open Access Journals (Sweden)

    Grauben José Alves de Assis

    2003-04-01

    Full Text Available Estudos anteriores documentaram a formação de relações de equivalência a partir do treino com pareamento consistente de estímulos. Este estudo, com figuras usuais, objetivou verificar os efeitos de um procedimento similar, mas com atraso na apresentação do modelo, em oito universitários de ambos os sexos. Foi usado um microcomputador com tela sensível ao toque. No ensino das discriminações condicionais AB e AC, intercalado aos testes de simetria BA e CA, e de equivalência BC e CB, o modelo era apresentado na "janela" central da tela; após a resposta ao modelo, este ficava ausente, e três estímulos de comparação, um dos quais o consistente (Sc, eram apresentados, simultaneamente, nas "janelas" laterais, sem conseqüências diferenciais para as respostas corretas e incorretas. Sete participantes alcançaram o critério (100% de acerto, cinco demonstraram as relações de simetria e um demonstrou equivalência. Esses resultados replicaram parcialmente os estudos anteriores.Previous studies have shown the formation of equivalence relations following training by stimulus consistency matching. Using common figures as stimuli, the aim of this experiment was to verify the effects of a similar procedure involving, however, delayed smaple stimulus presentation among eight university students of both sexes. A microcomputer with a touch-sensitive screen was utilized. Between training of conditional discriminations, AB and AC, symmetry (BA, CA and equivalence tests (BC, CB were inserted; the sample stimulus appeared in the center of the screen. Following response, the sample was withdrawn, and three comparison stimuli - one of them consistent - were shown simultaneously in the side windows, without differential consequences for correct or incorrect responses. Seven respondents reached criterion, five demonstrated having attained symmetry, and one, equivalence relations. These results replicated, in part, the outcomes of previous experiments.

  7. Effects of sample treatments on genome recovery via single-cell genomics

    Energy Technology Data Exchange (ETDEWEB)

    Clingenpeel, Scott [USDOE Joint Genome Institute (JGI), Walnut Creek, CA (United States); Schwientek, Patrick [USDOE Joint Genome Institute (JGI), Walnut Creek, CA (United States); Hugenholtz, Philip [Univ. of Queensland, Brisbane (Australia); Woyke, Tanja [USDOE Joint Genome Institute (JGI), Walnut Creek, CA (United States)

    2014-06-13

    It is known that single-cell genomics is a powerful tool for accessing genetic information from uncultivated microorganisms. Methods of handling samples before single-cell genomic amplification may affect the quality of the genomes obtained. Using three bacterial strains we demonstrate that, compared to cryopreservation, lower-quality single-cell genomes are recovered when the sample is preserved in ethanol or if the sample undergoes fluorescence in situ hybridization, while sample preservation in paraformaldehyde renders it completely unsuitable for sequencing.

  8. Stimulus control: Part I

    OpenAIRE

    Dinsmoor, James A.

    1995-01-01

    In his effort to distinguish operant from respondent conditioning, Skinner stressed the lack of an eliciting stimulus and rejected the prevailing stereotype of Pavlovian “stimulus—response” psychology. But control by antecedent stimuli, whether classified as conditional or discriminative, is ubiquitous in the natural setting. With both respondent and operant behavior, symmetrical gradients of generalization along unrelated dimensions may be obtained following differential reinforcement in the...

  9. Standard Specification for Sampling Single-Phase Geothermal Liquid or Steam for Purposes of Chemical Analysis

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    1983-01-01

    1.1 This specification covers the basic requirements for equipment to be used for the collection of uncontaminated and representative samples from single-phase geothermal liquid or steam. Geopressured liquids are included. See Fig 1.

  10. Optimal sampling strategies to assess inulin clearance in children by the inulin single-injection method

    NARCIS (Netherlands)

    van Rossum, Lyonne K.; Mathot, Ron A. A.; Cransberg, Karlien; Vulto, Arnold G.

    2003-01-01

    Glomerular filtration rate in patients can be determined by estimating the plasma clearance of inulin with the single-injection method. In this method, a single bolus injection of inulin is administered and several blood samples are collected. For practical and convenient application of this method

  11. Contextual dependencies in a stimulus equivalence paradigm

    NARCIS (Netherlands)

    Dibbets, P.; Maes, J.H.R.; Vossen, J.M.H.

    2002-01-01

    Two experiments with human subjects assessed contextual dependencies in a stimulus equivalence paradigm. Subjects learned to form two sets of stimuli in a matching-to-sample training procedure. Each set was presented against one of two different background colours, the contextual cues. At test, the

  12. Analysis of U and Pu resin bead samples with a single stage mass spectrometer

    International Nuclear Information System (INIS)

    Smith, D.H.; Walker, R.L.; Bertram, L.K.; Carter, J.A.

    1979-01-01

    Resin bead sampling enables the shipment of nanogram U and Pu quantities for analysis. Application of this sampling technique to safeguards was investigated with a single-stage mass spectrometer. Standards gave results in good agreement with NBS certified values. External precisions of +-0.5% were obtained on isotopic ratios of approx. 0.01; precisions on quantitative measurements are +-1.0%

  13. Analysis of multiple single nucleotide polymorphisms (SNP) on DNA traces from plasma and dried blood samples

    NARCIS (Netherlands)

    Catsburg, Arnold; van der Zwet, Wil C.; Morre, Servaas A.; Ouburg, Sander; Vandenbroucke-Grauls, Christina M. J. E.; Savelkoul, Paul H. M.

    2007-01-01

    Reliable analysis of single nucleotide polymorphisms (SNPs) in DNA derived from samples containing low numbers of cells or from suboptimal sources can be difficult. A new procedure to characterize multiple SNPs in traces of DNA from plasma and old dried blood samples was developed. Six SNPs in the

  14. Quantitative Single-letter Sequencing: a method for simultaneously monitoring numerous known allelic variants in single DNA samples

    Directory of Open Access Journals (Sweden)

    Duborjal Hervé

    2008-02-01

    Full Text Available Abstract Background Pathogens such as fungi, bacteria and especially viruses, are highly variable even within an individual host, intensifying the difficulty of distinguishing and accurately quantifying numerous allelic variants co-existing in a single nucleic acid sample. The majority of currently available techniques are based on real-time PCR or primer extension and often require multiplexing adjustments that impose a practical limitation of the number of alleles that can be monitored simultaneously at a single locus. Results Here, we describe a novel method that allows the simultaneous quantification of numerous allelic variants in a single reaction tube and without multiplexing. Quantitative Single-letter Sequencing (QSS begins with a single PCR amplification step using a pair of primers flanking the polymorphic region of interest. Next, PCR products are submitted to single-letter sequencing with a fluorescently-labelled primer located upstream of the polymorphic region. The resulting monochromatic electropherogram shows numerous specific diagnostic peaks, attributable to specific variants, signifying their presence/absence in the DNA sample. Moreover, peak fluorescence can be quantified and used to estimate the frequency of the corresponding variant in the DNA population. Using engineered allelic markers in the genome of Cauliflower mosaic virus, we reliably monitored six different viral genotypes in DNA extracted from infected plants. Evaluation of the intrinsic variance of this method, as applied to both artificial plasmid DNA mixes and viral genome populations, demonstrates that QSS is a robust and reliable method of detection and quantification for variants with a relative frequency of between 0.05 and 1. Conclusion This simple method is easily transferable to many other biological systems and questions, including those involving high throughput analysis, and can be performed in any laboratory since it does not require specialized

  15. Highly Reconfigurable Beamformer Stimulus Generator

    Directory of Open Access Journals (Sweden)

    Vaviļina E.

    2018-02-01

    Full Text Available The present paper proposes a highly reconfigurable beamformer stimulus generator of radar antenna array, which includes three main blocks: settings of antenna array, settings of objects (signal sources and a beamforming simulator. Following from the configuration of antenna array and object settings, different stimulus can be generated as the input signal for a beamformer. This stimulus generator is developed under a greater concept with two utterly independent paths where one is the stimulus generator and the other is the hardware beamformer. Both paths can be complemented in final and in intermediate steps as well to check and improve system performance. This way the technology development process is promoted by making each of the future hardware steps more substantive. Stimulus generator configuration capabilities and test results are presented proving the application of the stimulus generator for FPGA based beamforming unit development and tuning as an alternative to an actual antenna system.

  16. Comparison of Single-Point and Continuous Sampling Methods for Estimating Residential Indoor Temperature and Humidity.

    Science.gov (United States)

    Johnston, James D; Magnusson, Brianna M; Eggett, Dennis; Collingwood, Scott C; Bernhardt, Scott A

    2015-01-01

    Residential temperature and humidity are associated with multiple health effects. Studies commonly use single-point measures to estimate indoor temperature and humidity exposures, but there is little evidence to support this sampling strategy. This study evaluated the relationship between single-point and continuous monitoring of air temperature, apparent temperature, relative humidity, and absolute humidity over four exposure intervals (5-min, 30-min, 24-hr, and 12-days) in 9 northern Utah homes, from March-June 2012. Three homes were sampled twice, for a total of 12 observation periods. Continuous data-logged sampling was conducted in homes for 2-3 wks, and simultaneous single-point measures (n = 114) were collected using handheld thermo-hygrometers. Time-centered single-point measures were moderately correlated with short-term (30-min) data logger mean air temperature (r = 0.76, β = 0.74), apparent temperature (r = 0.79, β = 0.79), relative humidity (r = 0.70, β = 0.63), and absolute humidity (r = 0.80, β = 0.80). Data logger 12-day means were also moderately correlated with single-point air temperature (r = 0.64, β = 0.43) and apparent temperature (r = 0.64, β = 0.44), but were weakly correlated with single-point relative humidity (r = 0.53, β = 0.35) and absolute humidity (r = 0.52, β = 0.39). Of the single-point RH measures, 59 (51.8%) deviated more than ±5%, 21 (18.4%) deviated more than ±10%, and 6 (5.3%) deviated more than ±15% from data logger 12-day means. Where continuous indoor monitoring is not feasible, single-point sampling strategies should include multiple measures collected at prescribed time points based on local conditions.

  17. Sample Size Induced Brittle-to-Ductile Transition of Single-Crystal Aluminum Nitride

    Science.gov (United States)

    2015-08-01

    Aluminum Nitride by GA Gazonas and JW McCauley Weapons and Materials Research Directorate, ARL JJ Guo, KM Reddy, A Hirata, T Fujita, and MW Chen...Sample Size Induced Brittle-to-Ductile Transition of Single-Crystal Aluminum Nitride 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT...their microscopic structure. In this study, we report a size induced brittle-to-ductile transition in single-crystal aluminum nitride (AlN). When the

  18. Assessing the Validity of Single-item Life Satisfaction Measures: Results from Three Large Samples

    Science.gov (United States)

    Cheung, Felix; Lucas, Richard E.

    2014-01-01

    Purpose The present paper assessed the validity of single-item life satisfaction measures by comparing single-item measures to the Satisfaction with Life Scale (SWLS) - a more psychometrically established measure. Methods Two large samples from Washington (N=13,064) and Oregon (N=2,277) recruited by the Behavioral Risk Factor Surveillance System (BRFSS) and a representative German sample (N=1,312) recruited by the Germany Socio-Economic Panel (GSOEP) were included in the present analyses. Single-item life satisfaction measures and the SWLS were correlated with theoretically relevant variables, such as demographics, subjective health, domain satisfaction, and affect. The correlations between the two life satisfaction measures and these variables were examined to assess the construct validity of single-item life satisfaction measures. Results Consistent across three samples, single-item life satisfaction measures demonstrated substantial degree of criterion validity with the SWLS (zero-order r = 0.62 – 0.64; disattenuated r = 0.78 – 0.80). Patterns of statistical significance for correlations with theoretically relevant variables were the same across single-item measures and the SWLS. Single-item measures did not produce systematically different correlations compared to the SWLS (average difference = 0.001 – 0.005). The average absolute difference in the magnitudes of the correlations produced by single-item measures and the SWLS were very small (average absolute difference = 0.015 −0.042). Conclusions Single-item life satisfaction measures performed very similarly compared to the multiple-item SWLS. Social scientists would get virtually identical answer to substantive questions regardless of which measure they use. PMID:24890827

  19. Assessing the validity of single-item life satisfaction measures: results from three large samples.

    Science.gov (United States)

    Cheung, Felix; Lucas, Richard E

    2014-12-01

    The present paper assessed the validity of single-item life satisfaction measures by comparing single-item measures to the Satisfaction with Life Scale (SWLS)-a more psychometrically established measure. Two large samples from Washington (N = 13,064) and Oregon (N = 2,277) recruited by the Behavioral Risk Factor Surveillance System and a representative German sample (N = 1,312) recruited by the Germany Socio-Economic Panel were included in the present analyses. Single-item life satisfaction measures and the SWLS were correlated with theoretically relevant variables, such as demographics, subjective health, domain satisfaction, and affect. The correlations between the two life satisfaction measures and these variables were examined to assess the construct validity of single-item life satisfaction measures. Consistent across three samples, single-item life satisfaction measures demonstrated substantial degree of criterion validity with the SWLS (zero-order r = 0.62-0.64; disattenuated r = 0.78-0.80). Patterns of statistical significance for correlations with theoretically relevant variables were the same across single-item measures and the SWLS. Single-item measures did not produce systematically different correlations compared to the SWLS (average difference = 0.001-0.005). The average absolute difference in the magnitudes of the correlations produced by single-item measures and the SWLS was very small (average absolute difference = 0.015-0.042). Single-item life satisfaction measures performed very similarly compared to the multiple-item SWLS. Social scientists would get virtually identical answer to substantive questions regardless of which measure they use.

  20. High-pressure oxygenation of thin-wall YBCO single-domain samples

    International Nuclear Information System (INIS)

    Chaud, X; Savchuk, Y; Sergienko, N; Prikhna, T; Diko, P

    2008-01-01

    The oxygen annealing of ReBCO bulk material, necessary to achieve superconducting properties, usually induces micro- and macro-cracks. This leads to a crack-assisted oxygenation process that allows oxygenating large bulk samples faster than single crystals. But excellent superconducting properties are cancelled by the poor mechanical ones. More progressive oxygenation strategy has been shown to reduce drastically the oxygenation cracks. The problem then arises to keep a reasonable annealing time. The concept of bulk Y123 single-domain samples with thin-wall geometry has been introduced to bypass the inherent limitation due to a slow oxygen diffusion rate. But it is not enough. The use of a high oxygen pressure (16 MPa) enables to speed up further the process. It introduces a displacement in the equilibrium phase diagram towards higher temperatures, i.e., higher diffusion rates, to achieve a given oxygen content in the material. Remarkable results were obtained by applying such a high pressure oxygen annealing process on thin-wall single-domain samples. The trapped field of 16 mm diameter Y123 thin-wall single-domain samples was doubled (0.6T vs 0.3T at 77K) using an annealing time twice shorter (about 3 days). The initial development was made on thin bars. The advantage of thin-wall geometry is that such an annealing can be applied directly to a much larger sample

  1. Preparation and characterization of single crystal samples for high-pressure experiments

    Energy Technology Data Exchange (ETDEWEB)

    Farber, D; Antonangeli, D; Aracne, C; Benterou, J

    2005-10-26

    To date, most research utilizing the diamond anvil cell (DAC) has been conducted with polycrystalline samples, thus the results are limited to addressing average bulk properties. However, experiments on single crystals can yield data on a range of orientation dependent properties such as thermal and electrical conductivity, magnetic susceptibility, elasticity and plasticity. Here we report new procedures to produce extremely high-quality metallic single crystal samples of size compatible with DAC experiments in the Mbar range. So far, we have produced samples of zinc, Al{sub 2}O{sub 3}, cobalt, molybdenum and cerium, and have evaluated the quality of the finished samples with white-light interferometry, synchrotron x-ray diffraction and inelastic x-ray scattering.

  2. Carving Executive Control At Its Joints: Working Memory Capacity Predicts Stimulus-Stimulus, But Not Stimulus-Response, Conflict

    Science.gov (United States)

    Meier, Matt E.; Kane, Michael J.

    2015-01-01

    Three experiments examined the relation between working memory capacity (WMC) and two different forms of cognitive conflict: stimulus-stimulus (S-S) and stimulus-response (SR) interference. Our goal was to test whether WMC’s relation to conflict-task performance is mediated by stimulus-identification processes (captured by S-S conflict), response-selection processes (captured by S-R conflict), or both. In Experiment 1, subjects completed a single task presenting both S-S and S-R conflict trials, plus trials that combined the two conflict types. We limited ostensible goal-maintenance contributions to performance by requiring the same goal for all trial types and by presenting frequent conflict trials that reinforced the goal. WMC predicted resolution of S-S conflict as expected: Higher-WMC subjects showed reduced response time interference. Although WMC also predicted S-R interference, here, higher-WMC subjects showed increased error interference. Experiment 2A replicated these results in a version of the conflict task without combined S-S/S-R trials. Experiment 2B increased the proportion of congruent (non-conflict) trials to promote reliance on goal-maintenance processes. Here, higher-WMC subjects resolved both S-S and S-R conflict more successfully than did lower-WMC subjects. The results were consistent with Kane and Engle’s (2003) two-factor theory of cognitive control, according to which WMC predicts executive-task performance through goal-maintenance and conflict-resolution processes. However, the present results add specificity to the account by suggesting that higher-WMC subjects better resolve cognitive conflict because they more efficiently select relevant stimulus features against irrelevant, distracting ones. PMID:26120774

  3. Single injection 51Cr EDTA plasma clearance determination in children using capillary blood samples

    International Nuclear Information System (INIS)

    Broechner-Mortensen, J.; Christoffersen, J.

    1977-01-01

    The reliability of a determination of the total 51 Cr EDTA plasma clearance (e) (and with it the glomerular filtration rate), by a simplified single injection method (injected dose: 4.5 μCi per kg b.w.) using capillary blood samples (0.2 ml), was investigated in twenty children. Clearance values determined from capillary blood samples did not differ significantly from those measured simultaneously from venous blood samples, the mean ratio+-SD being 1.02+-0.06(n = 10). The reproducibility (total day-to-day variation) of E determined from capillary blood samples was 6.7% in children with decreased renal function (n = 3) and 6.9% in children with normal renal function (n = 7). The present data indicate that the use of capillary blood samples is an accurate and very precise approach for determination of E in children. (Auth.)

  4. Single- versus multiple-sample method to measure glomerular filtration rate.

    Science.gov (United States)

    Delanaye, Pierre; Flamant, Martin; Dubourg, Laurence; Vidal-Petiot, Emmanuelle; Lemoine, Sandrine; Cavalier, Etienne; Schaeffner, Elke; Ebert, Natalie; Pottel, Hans

    2018-01-08

    There are many different ways to measure glomerular filtration rate (GFR) using various exogenous filtration markers, each having their own strengths and limitations. However, not only the marker, but also the methodology may vary in many ways, including the use of urinary or plasma clearance, and, in the case of plasma clearance, the number of time points used to calculate the area under the concentration-time curve, ranging from only one (Jacobsson method) to eight (or more) blood samples. We collected the results obtained from 5106 plasma clearances (iohexol or 51Cr-ethylenediaminetetraacetic acid (EDTA)) using three to four time points, allowing GFR calculation using the slope-intercept method and the Bröchner-Mortensen correction. For each time point, the Jacobsson formula was applied to obtain the single-sample GFR. We used Bland-Altman plots to determine the accuracy of the Jacobsson method at each time point. The single-sample method showed within 10% concordances with the multiple-sample method of 66.4%, 83.6%, 91.4% and 96.0% at the time points 120, 180, 240 and ≥300 min, respectively. Concordance was poorer at lower GFR levels, and this trend is in parallel with increasing age. Results were similar in males and females. Some discordance was found in the obese subjects. Single-sample GFR is highly concordant with a multiple-sample strategy, except in the low GFR range (<30 mL/min). © The Author 2018. Published by Oxford University Press on behalf of ERA-EDTA. All rights reserved.

  5. Sampling and single particle analysis for the chemical characterisation of fine atmospheric particulates: A review.

    Science.gov (United States)

    Elmes, Michele; Gasparon, Massimo

    2017-11-01

    To better understand the potential environmental and human health impacts of fine airborne particulate matter (APM), detailed physical and chemical characterisation is required. The only means to accurately distinguish between the multiple compositions in APM is by single particle analysis. A variety of methods and instruments are available, which range from filter-based sample collection for off-line laboratory analysis to on-line instruments that detect the airborne particles and generate size distribution and chemical data in real time. There are many reasons for sampling particulates in the ambient atmosphere and as a consequence, different measurement strategies and sampling devices are used depending on the scientific objectives and subsequent analytical techniques. This review is designed as a guide to some of the techniques available for the sampling and subsequent chemical analysis of individual inorganic particles. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. A simple microfluidic dispenser for single-microparticle and cell samples.

    Science.gov (United States)

    Kasukurti, A; Eggleton, C D; Desai, S A; Disharoon, D I; Marr, D W M

    2014-12-21

    Non-destructive isolation of single-cells has become an important need for many biology research laboratories; however, there is a lack of easily employed and inexpensive tools. Here, we present a single-particle sample delivery approach fabricated from simple, economical components that may address this need. In this, we employ unique flow and timing strategies to bridge the significant force and length scale differences inherent in transitioning from single particle isolation to delivery. Demonstrating this approach, we use an optical trap to isolate individual microparticles and red blood cells that are dispensed within separate 50 μl droplets off a microfluidic chip for collection into microscope slides or microtiter plates.

  7. Investigation of applicability of extrapolation method for sample field determination in single-yoke measuring setup

    Czech Academy of Sciences Publication Activity Database

    Stupakov, Oleksandr

    2006-01-01

    Roč. 307, - (2006), s. 279-287 ISSN 0304-8853 R&D Projects: GA AV ČR(CZ) 1QS100100508 Institutional research plan: CEZ:AV0Z10100520 Keywords : magnetic measurement * open magnetic sample * surface field determination * single-yoke setup * magnetic non-destructive testing Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.212, year: 2006

  8. Chromium-51-EDTA clearance in adults with a single-plasma sample.

    Science.gov (United States)

    Mårtensson, J; Groth, S; Rehling, M; Gref, M

    1998-12-01

    In 1996, a committee on renal clearance recommended a mean sojourn time-based methodology for single-sample determination of plasma clearance of 99mTc-diethylenetriamine pentaacetic acid (DTPA) to be used on adults if the patient's glomerular filtration rate (GFR) is suspected to be >30 ml/min. The main purpose of this study was to derive a mean sojourn time-based formula for calculation of 51Cr-ethylenediamine tetraacetic acid (EDTA) clearance in adults. Two groups of patients with 51Cr-EDTA clearance (Cl) between 16 and 172 ml/min were studied. In Group I (n = 46), reference Cl was determined as a multiplasma sample, single-injection method (ClSM). Sixteen blood samples were drawn from 0 until 5 hr after a single intravenous injection of 51Cr-EDTA. In Group II (n = 1046), reference Cl was determined by the Brøchner-Mortensen four-sample clearance method (ClBM). The plasma time-activity curves of Group I were used to derive two mean sojourn time-based formulas (Formulas 1 and 2) for calculation of a single-sample clearance. Formula 1 was derived from the entire time-activity curve, whereas the derivation of Formula 2 used only the final slope of the time-activity curve. The accuracy of the two formulas and the Christensen and Groth 99mTc-DTPA formula was tested on Group II. Chromium-51-EDTA Cl calculated by Formula 1 was almost identical to the Cl calculated by the reference Cl method (r = 0.982; SDdiff = 5.82 ml/min). Both 51Cr-EDTA Cl calculated by Formula 2 and by the 99mTc-DTPA formula showed close correlation with the reference method (r = 0.976, r = 0.985, respectively) but systematically overestimated GFR for the whole range of clearance values by 3.5 and 3.2 ml/min (ptime methodology. The determination is marginally more accurate (ptime-activity curve than from only the final slope. The single-sample formula derived for determination of 99mTc-DTPA Cl tends slightly to overestimate GFR if used to calculate 51Cr-EDTA Cl.

  9. Microwave-assisted headspace single-drop microextration of chlorobenzenes from water samples

    Energy Technology Data Exchange (ETDEWEB)

    Vidal, Lorena [Departamento de Quimica Analitica, Nutricion y Bromatologia, Universidad de Alicante, P.O. Box 99, E-03080 Alicante (Spain); Domini, Claudia E. [Departamento de Quimica Analitica, Nutricion y Bromatologia, Universidad de Alicante, P.O. Box 99, E-03080 Alicante (Spain); Grane, Nuria [Departamento de Quimica Analitica, Nutricion y Bromatologia, Universidad de Alicante, P.O. Box 99, E-03080 Alicante (Spain); Psillakis, Elefteria [Department of Environmental Engineering, Technical University of Crete, Polytechneioupolis, GR-73100 Chania, Crete (Greece); Canals, Antonio [Departamento de Quimica Analitica, Nutricion y Bromatologia, Universidad de Alicante, P.O. Box 99, E-03080 Alicante (Spain)]. E-mail: a.canals@ua.es

    2007-05-29

    A one-step and in-situ sample preparation method used for quantifying chlorobenzene compounds in water samples has been developed, coupling microwave and headspace single-drop microextraction (MW-HS-SDME). The chlorobenzenes in water samples were extracted directly onto an ionic liquid single-drop in headspace mode under the aid of microwave radiation. For optimization, a Plackett-Burman screening design was initially used, followed by a mixed-level factorial design. The factors considered were: drop volume, aqueous sample volume, stirring speed, ionic strength, extraction time, ionic liquid type, microwave power and length of the Y-shaped glass-tube. The optimum experimental conditions found from this statistical evaluation were: a 5 {mu}L microdrop of 1-hexyl-3-methylimidazolium hexafluorophosphate exposed for 20 min to the headspace of a 30 mL aqueous sample, irradiated by microwaves at 200 W and placed in a 50 mL spherical flask connected to a 25 cm Y-shaped glass-tube. Under the optimised experimental conditions, the response of a high performance liquid chromatographic system was found to be linear over the range studied and with correlation coefficients ranging between 0.9995 and 0.9999. The method showed a good level of repeatability, with relative standard deviations varying between 2.3 and 8.3% (n = 5). Detection limits were found in the low {mu}g L{sup -1} range varying between 0.016 and 0.039 {mu}g L{sup -1}. Overall, the performance of the proposed method demonstrated the favourable effect of microwave sample irradiation upon HS-SDME. Finally, recovery studies from different types of environmental water samples revealed that matrix had little effect upon extraction.

  10. Microwave-assisted headspace single-drop microextration of chlorobenzenes from water samples

    International Nuclear Information System (INIS)

    Vidal, Lorena; Domini, Claudia E.; Grane, Nuria; Psillakis, Elefteria; Canals, Antonio

    2007-01-01

    A one-step and in-situ sample preparation method used for quantifying chlorobenzene compounds in water samples has been developed, coupling microwave and headspace single-drop microextraction (MW-HS-SDME). The chlorobenzenes in water samples were extracted directly onto an ionic liquid single-drop in headspace mode under the aid of microwave radiation. For optimization, a Plackett-Burman screening design was initially used, followed by a mixed-level factorial design. The factors considered were: drop volume, aqueous sample volume, stirring speed, ionic strength, extraction time, ionic liquid type, microwave power and length of the Y-shaped glass-tube. The optimum experimental conditions found from this statistical evaluation were: a 5 μL microdrop of 1-hexyl-3-methylimidazolium hexafluorophosphate exposed for 20 min to the headspace of a 30 mL aqueous sample, irradiated by microwaves at 200 W and placed in a 50 mL spherical flask connected to a 25 cm Y-shaped glass-tube. Under the optimised experimental conditions, the response of a high performance liquid chromatographic system was found to be linear over the range studied and with correlation coefficients ranging between 0.9995 and 0.9999. The method showed a good level of repeatability, with relative standard deviations varying between 2.3 and 8.3% (n = 5). Detection limits were found in the low μg L -1 range varying between 0.016 and 0.039 μg L -1 . Overall, the performance of the proposed method demonstrated the favourable effect of microwave sample irradiation upon HS-SDME. Finally, recovery studies from different types of environmental water samples revealed that matrix had little effect upon extraction

  11. Optimal stimulus shapes for neuronal excitation.

    Directory of Open Access Journals (Sweden)

    Daniel B Forger

    2011-07-01

    Full Text Available An important problem in neuronal computation is to discern how features of stimuli control the timing of action potentials. One aspect of this problem is to determine how an action potential, or spike, can be elicited with the least energy cost, e.g., a minimal amount of applied current. Here we show in the Hodgkin & Huxley model of the action potential and in experiments on squid giant axons that: 1 spike generation in a neuron can be highly discriminatory for stimulus shape and 2 the optimal stimulus shape is dependent upon inputs to the neuron. We show how polarity and time course of post-synaptic currents determine which of these optimal stimulus shapes best excites the neuron. These results are obtained mathematically using the calculus of variations and experimentally using a stochastic search methodology. Our findings reveal a surprising complexity of computation at the single cell level that may be relevant for understanding optimization of signaling in neurons and neuronal networks.

  12. Detection of Janus Kinase 2 gene single point mutation in real samples with electrochemical DNA biosensor.

    Science.gov (United States)

    Topkaya, Seda Nur; Kosova, Buket; Ozsoz, Mehmet

    2014-02-15

    Janus Kinase 2 (JAK2) gene single point mutations, which have been reported to be associated with myeloproliferative disorders, are usually detected through conventional methods such as melting curve assays, allele-specific and quantitative Polymerase Chain Reactions (PCRs). Herein, an electrochemical biosensor for the detection of a Guanine (G) to Thymine (T) transversion at nucleotide position 1849 of the JAK2 gene was reported. Due to clinical importance of this mutation, easy and sensitive tests are needed to be developed. Our aim was to design a biosensor system that is capable of detecting the mutation within less than 1h with high sensitivity. For these purposes, an electrochemical sensing system was developed based on detecting hybridization. Hybridization between probe and its target and discrimination of single point mutation was investigated by monitoring guanine oxidation signals observed at +1.0 V with Differential Pulse Voltammetry (DPV) by using synthetic oligonucleotides and Polymerase Chain Reaction (PCR) amplicons. Hybridization between probe and PCR amplicons was also determined with Electrochemical Impedance Spectroscopy (EIS). We successfully detect hybridization first in synthetic samples, and ultimately in real samples involving blood samples from patients as well as additional healthy controls. The limit of detection (S/N=3) was calculated as 44 pmol of target sequence in a 40-μl reaction volume in real samples. Copyright © 2013 Elsevier B.V. All rights reserved.

  13. Simple and Reproducible Sample Preparation for Single-Shot Phosphoproteomics with High Sensitivity

    DEFF Research Database (Denmark)

    Jersie-Christensen, Rosa R.; Sultan, Abida; Olsen, Jesper V

    2016-01-01

    The traditional sample preparation workflow for mass spectrometry (MS)-based phosphoproteomics is time consuming and usually requires multiple steps, e.g., lysis, protein precipitation, reduction, alkylation, digestion, fractionation, and phosphopeptide enrichment. Each step can introduce chemical...... artifacts, in vitro protein and peptide modifications, and contaminations. Those often result in sample loss and affect the sensitivity, dynamic range and accuracy of the mass spectrometric analysis. Here we describe a simple and reproducible phosphoproteomics protocol, where lysis, denaturation, reduction......, and alkylation are performed in a single step, thus reducing sample loss and increasing reproducibility. Moreover, unlike standard cell lysis procedures the cell harvesting is performed at high temperatures (99 °C) and without detergents and subsequent need for protein precipitation. Phosphopeptides are enriched...

  14. Carving Executive Control at Its Joints: Working Memory Capacity Predicts Stimulus-Stimulus, but Not Stimulus-Response, Conflict

    Science.gov (United States)

    Meier, Matt E.; Kane, Michael J.

    2015-01-01

    Three experiments examined the relation between working memory capacity (WMC) and 2 different forms of cognitive conflict: stimulus-stimulus (S-S) and stimulus-response (S-R) interference. Our goal was to test whether WMC's relation to conflict-task performance is mediated by stimulus-identification processes (captured by S-S conflict),…

  15. A single sample GnRHa stimulation test in the diagnosis of precocious puberty

    Directory of Open Access Journals (Sweden)

    Yazdani Parvin

    2012-07-01

    Full Text Available Abstract Context Gonadotropin-releasing hormone (GnRH has been the standard test for diagnosing central precocious puberty. Because GnRH is no longer available, GnRH analogues (GnRHa are now used. Random LH concentration, measured by the third-generation immunochemiluminometric assay, is a useful screening tool for central precocious puberty. However, GnRHa stimulation test should be considered, when a basal LH measurement is inconclusive. However optimal sampling times for luteinizing hormone (LH have yet to be established. Purpose To determine the appropriate sampling time for LH post leuprolide challenge. Methods A retrospective analysis of multi-sample GnRHa stimulation tests performed in 155 children (aged 1–9 years referred for precocious puberty to Texas Children’s Hospital. After 20 mcg/kg of SQ leuprolide acetate, samples were obtained at 0, 1, 3, and 6 hours. Results Of 71 children with clinical evidence of central precocious puberty, fifty nine children had a peak LH >5 mIU/mL. 52 (88% of these responders had positive responses at 1 hour (95% CI is 80–96%, whereas all 59 children (100% had a peak LH response >5 mIU/mL at 3 hours (95% CI is 94-100%, P = 0.005. Conclusions A single serum LH sample collected 3 hours post GnRHa challenge is the optimal sample to establish the diagnosis of central precocious puberty.

  16. Zooplankton diversity analysis through single-gene sequencing of a community sample

    Directory of Open Access Journals (Sweden)

    Nishida Mutsumi

    2009-09-01

    Full Text Available Abstract Background Oceans cover more than 70% of the earth's surface and are critical for the homeostasis of the environment. Among the components of the ocean ecosystem, zooplankton play vital roles in energy and matter transfer through the system. Despite their importance, understanding of zooplankton biodiversity is limited because of their fragile nature, small body size, and the large number of species from various taxonomic phyla. Here we present the results of single-gene zooplankton community analysis using a method that determines a large number of mitochondrial COI gene sequences from a bulk zooplankton sample. This approach will enable us to estimate the species richness of almost the entire zooplankton community. Results A sample was collected from a depth of 721 m to the surface in the western equatorial Pacific off Pohnpei Island, Micronesia, with a plankton net equipped with a 2-m2 mouth opening. A total of 1,336 mitochondrial COI gene sequences were determined from the cDNA library made from the sample. From the determined sequences, the occurrence of 189 species of zooplankton was estimated. BLASTN search results showed high degrees of similarity (>98% between the query and database for 10 species, including holozooplankton and merozooplankton. Conclusion In conjunction with the Census of Marine Zooplankton and Barcode of Life projects, single-gene zooplankton community analysis will be a powerful tool for estimating the species richness of zooplankton communities.

  17. Estimation of technetium 99m mercaptoacetyltriglycine plasma clearance by use of one single plasma sample

    International Nuclear Information System (INIS)

    Mueller-Suur, R.; Magnusson, G.; Karolinska Inst., Stockholm; Bois-Svensson, I.; Jansson, B.

    1991-01-01

    Recent studies have shown that technetium 99m mercaptoacetyltriglycine (MAG-3) is a suitable replacement for iodine 131 or 123 hippurate in gamma-camera renography. Also, the determination of its clearance is of value, since it correlates well with that of hippurate and thus may be an indirect measure of renal plasma flow. In order to simplify the clearance method we developed formulas for the estimation of plasma clearance of MAG-3 based on a single plasma sample and compared them with the multiple sample method based on 7 plasma samples. The correlation to effective renal plasma flow (ERPF) (according to Tauxe's method, using iodine 123 hippurate), which ranged from 75 to 654 ml/min per 1.73 m 2 , was determined in these patients. Using the developed regression equations the error of estimate for the simplified clearance method was acceptably low (18-14 ml/min), when the single plasma sample was taken 44-64 min post-injection. Formulas for different sampling times at 44, 48, 52, 56, 60 and 64 min are given, and we recommend 60 min as optimal, with an error of estimate of 15.5 ml/min. The correlation between the MAG-3 clearances and ERPF was high (r=0.90). Since normal values for MAG-3 clearance are not yet available, transformation to estimated ERPF values by the regression equation (ERPF=1.86xC MAG-3 +4.6) could be of clinical value in order to compare it with the normal values for ERPF given in the literature. (orig.)

  18. Structural and magnetic properties evolution study method using a single ribbon-shaped sample

    Science.gov (United States)

    Moya, Javier A.

    2017-06-01

    A new type of study is presented for magnetic and structural characterization of amorphous or nanocrystalline metallic alloys in ribbon or wire-shaped samples. A single sample is subjecting to successive steps of flash isocurrent heat treatments with increasing duration in time, followed by a rapid cooling, while magneto-electric properties evolution are scanned in situ at room temperature. When one set of isocurrent heat treatments is finished, the annealing current is increased and a new set of isocurrent treatments starts. The properties studied were the saturation magnetization and the coercive field at 50 Hz, magnetic permeability at 100 kHz and electrical resistance from where we also obtained the crystalline fraction. The method was applied on two samples of Finemet-like alloys and the results were analyzed from the perspective of current literature. With the present method it is possible to obtain a general and meticulous understanding of the structural and magnetic evolution of the samples tested, with a considerable saving of time and samples.

  19. Audiovisual integration of stimulus transients

    DEFF Research Database (Denmark)

    Andersen, Tobias; Mamassian, Pascal

    2008-01-01

    A change in sound intensity can facilitate luminance change detection. We found that this effect did not depend on whether sound intensity and luminance increased or decreased. In contrast, luminance identification was strongly influenced by the congruence of luminance and sound intensity change...... leaving only unsigned stimulus transients as the basis for audiovisual integration. Facilitation of luminance detection occurred even with varying audiovisual stimulus onset asynchrony and even when the sound lagged behind the luminance change by 75 ms supporting the interpretation that perceptual...... integration rather than a reduction of temporal uncertainty or effects of attention caused the effect....

  20. Keynesian stimulus versus classical austerity

    OpenAIRE

    Laurence Seidman

    2012-01-01

    Keynesians know that if US austerity advocates had received just a few more votes in the November 2008 election, there would have been no fiscal stimulus or financial rescue in 2009 and the Great Recession would have turned into a second great depression. ‘Keynesian’ means recognizing the crucial role of aggregate demand, grasping the paradox of saving, advocating fiscal stimulus (tax cuts as well as government spending) in a recession despite the temporary increase in debt that it genera...

  1. A Bayesian predictive sample size selection design for single-arm exploratory clinical trials.

    Science.gov (United States)

    Teramukai, Satoshi; Daimon, Takashi; Zohar, Sarah

    2012-12-30

    The aim of an exploratory clinical trial is to determine whether a new intervention is promising for further testing in confirmatory clinical trials. Most exploratory clinical trials are designed as single-arm trials using a binary outcome with or without interim monitoring for early stopping. In this context, we propose a Bayesian adaptive design denoted as predictive sample size selection design (PSSD). The design allows for sample size selection following any planned interim analyses for early stopping of a trial, together with sample size determination before starting the trial. In the PSSD, we determine the sample size using the method proposed by Sambucini (Statistics in Medicine 2008; 27:1199-1224), which adopts a predictive probability criterion with two kinds of prior distributions, that is, an 'analysis prior' used to compute posterior probabilities and a 'design prior' used to obtain prior predictive distributions. In the sample size determination of the PSSD, we provide two sample sizes, that is, N and N(max) , using two types of design priors. At each interim analysis, we calculate the predictive probabilities of achieving a successful result at the end of the trial using the analysis prior in order to stop the trial in case of low or high efficacy (Lee et al., Clinical Trials 2008; 5:93-106), and we select an optimal sample size, that is, either N or N(max) as needed, on the basis of the predictive probabilities. We investigate the operating characteristics through simulation studies, and the PSSD retrospectively applies to a lung cancer clinical trial. (243) Copyright © 2012 John Wiley & Sons, Ltd.

  2. Stimulus Effects on Local Preference: Stimulus-Response Contingencies, Stimulus-Food Pairing, and Stimulus-Food Correlation

    Science.gov (United States)

    Davison, Michael; Baum, William M.

    2010-01-01

    Four pigeons were trained in a procedure in which concurrent-schedule food ratios changed unpredictably across seven unsignaled components after 10 food deliveries. Additional green-key stimulus presentations also occurred on the two alternatives, sometimes in the same ratio as the component food ratio, and sometimes in the inverse ratio. In eight…

  3. Prediction of two-sample 99mTc-diethylene triamine pentaacetic acid plasma clearance from single-sample method

    International Nuclear Information System (INIS)

    Zuo Li; Ma Ying-Chun; Wang Mei; Zhang Chun-Li; Wang Rong-Fu; Wang Hai-Yan

    2005-01-01

    The objective of this study was to develop an equation to predict dual plasma sample method (DPSM) 99m Tc-diethylene triamine pentaacetic acid ( 99m Tc-DTPA) plasma clearance from single plasma sample method (SPSM), and to clarify the condition in which DPSM can be substituted by SPSM in measurement of glomerular filtration rate (GFR). Patients with chronic kidney disease (CKD) were selected. Watson modified Christensen and Groth equation was used to calculate 99m Tc-DTPA plasma clearance by SPSM (sGFR). The equation recommended by the Nephrourology Committee of the Society of Nuclear Medicine was used to calculate 99m Tc-DTPA plasma clearance by DPSM (tGFR) in each patient. The difference between sGFR and tGFR was expressed as percent of the average of these two methods, and tGFR was predicted from sGFR. Plasma creatinine was measured by the kinetic picrate method, and GFR estimated by abbreviated modification of diet in renal disease (MDRD) equation (aGFR) and Cockcroft-Gault equation (cGFR) were evaluated as criteria in selection of DPSM and SPSM. Three hundred and sixty-nine patients with CKD were selected (208 male and 161 female). The average age and body weight were 51.4±15.5 years and 67.2±12.5 kg, respectively. The causes of CKD were glomerular disease, renal arterial stenosis, chronic tubulointerstitial disease, and other causes or causes unknown. The average tGFR was 62.9±36.5 ml/min/1.73 m 2 , ranging from 1-180 ml/min/1.73 m 2 . sGFR was significantly correlated with tGFR (r=0.9194, p 2 ; in contrast, then tGFR was±30 ml/min/1.73 m 2 , the difference was constant (-1.1%, 95% confidence interval -18.3%, 16.1%), and tGFR could be predicted from sGFR using the equation: predicted tGFR (ml/min/1.73 m 2 )=7 4244+0.7318 x sGFR+0.0022 x sGFR 2 (n=299, r 2 =0.9428, p 2 , the diagnostic sensitivity of a cut off value of aGFR=45 ml/min/1.73 m 2 was 91.8%, and recommended as a criterion in the selection of DPSM and SPSM. When GFR ≥30 ml/min/1.73 m 2 , t

  4. Variation in orgasm occurrence by sexual orientation in a sample of U.S. singles.

    Science.gov (United States)

    Garcia, Justin R; Lloyd, Elisabeth A; Wallen, Kim; Fisher, Helen E

    2014-11-01

    Despite recent advances in understanding orgasm variation, little is known about ways in which sexual orientation is associated with men's and women's orgasm occurrence. To assess orgasm occurrence during sexual activity across sexual orientation categories. Data were collected by Internet questionnaire from 6,151 men and women (ages 21-65+ years) as part of a nationally representative sample of single individuals in the United States. Analyses were restricted to a subsample of 2,850 singles (1,497 men, 1,353 women) who had experienced sexual activity in the past 12 months. Participants reported their sex/gender, self-identified sexual orientation (heterosexual, gay/lesbian, bisexual), and what percentage of the time they experience orgasm when having sex with a familiar partner. Mean occurrence rate for experiencing orgasm during sexual activity with a familiar partner was 62.9% among single women and 85.1% among single men, which was significantly different (F1,2848  = 370.6, P sexual orientation: heterosexual men 85.5%, gay men 84.7%, bisexual men 77.6% (F2,1494  = 2.67, P = 0.07, η(2)  = 0.004). For women, however, mean occurrence rate of orgasm varied significantly by sexual orientation: heterosexual women 61.6%, lesbian women 74.7%, bisexual women 58.0% (F2,1350  = 10.95, P sexual orientation, have less predictable, more varied orgasm experiences than do men and that for women, but not men, the likelihood of orgasm varies with sexual orientation. These findings demonstrate the need for further investigations into the comparative sexual experiences and sexual health outcomes of sexual minorities. © 2014 International Society for Sexual Medicine.

  5. The Stimulus Movement Effect: Allocation of Attention or Artifact?

    Science.gov (United States)

    Washburn, David A.

    1993-01-01

    In previous reports, including one by the author, learning has been shown to benefit by having discriminanda move rather than remain stationary. This stimulus movement effect might be attributed to several theoretical mechanisms, including attention, topological memory, and exposure duration. The series of experiments reported in this article was designed to Contrast these potential explanatory factors. Ten rhesus monkeys (Macaca mulatta) were tested on a variety of computerized tasks in which the stimuli remained stationary, flashed, or moved at systematically varied speeds. Performance was significantly best when the sample stimulus moved quickly and was poorest when the stimulus remained stationary. Further analysis of these data and other previously published data revealed that the distribution of the stimulus movement effect across trials supported an attention allocation interpretation.

  6. MPLEx: a Robust and Universal Protocol for Single-Sample Integrative Proteomic, Metabolomic, and Lipidomic Analyses

    Energy Technology Data Exchange (ETDEWEB)

    Nakayasu, Ernesto S.; Nicora, Carrie D.; Sims, Amy C.; Burnum-Johnson, Kristin E.; Kim, Young-Mo; Kyle, Jennifer E.; Matzke, Melissa M.; Shukla, Anil K.; Chu, Rosalie K.; Schepmoes, Athena A.; Jacobs, Jon M.; Baric, Ralph S.; Webb-Robertson, Bobbie-Jo; Smith, Richard D.; Metz, Thomas O.; Chia, Nicholas

    2016-05-03

    ABSTRACT

    Integrative multi-omics analyses can empower more effective investigation and complete understanding of complex biological systems. Despite recent advances in a range of omics analyses, multi-omic measurements of the same sample are still challenging and current methods have not been well evaluated in terms of reproducibility and broad applicability. Here we adapted a solvent-based method, widely applied for extracting lipids and metabolites, to add proteomics to mass spectrometry-based multi-omics measurements. Themetabolite,protein, andlipidextraction (MPLEx) protocol proved to be robust and applicable to a diverse set of sample types, including cell cultures, microbial communities, and tissues. To illustrate the utility of this protocol, an integrative multi-omics analysis was performed using a lung epithelial cell line infected with Middle East respiratory syndrome coronavirus, which showed the impact of this virus on the host glycolytic pathway and also suggested a role for lipids during infection. The MPLEx method is a simple, fast, and robust protocol that can be applied for integrative multi-omic measurements from diverse sample types (e.g., environmental,in vitro, and clinical).

    IMPORTANCEIn systems biology studies, the integration of multiple omics measurements (i.e., genomics, transcriptomics, proteomics, metabolomics, and lipidomics) has been shown to provide a more complete and informative view of biological pathways. Thus, the prospect of extracting different types of molecules (e.g., DNAs, RNAs, proteins, and metabolites) and performing multiple omics measurements on single samples is very attractive, but such studies are challenging due to the fact that the extraction conditions differ according to the molecule type. Here, we adapted an organic solvent-based extraction method that demonstrated

  7. Single-Tube Flow Cytometry Assay for the Detection of Mature Lymphoid Neoplasms in Paucicellular Samples.

    Science.gov (United States)

    Stacchini, Alessandra; Demurtas, Anna; Aliberti, Sabrina; Barreca, Antonella; Novero, Domenico; Pacchioni, Donatella

    2016-01-01

    Flow cytometry (FC) has become a useful support for cytomorphologic evaluation (CM) of fine-needle aspirates (FNA) and serous cavity effusions (SCE) in cases of suspected non-Hodgkin lymphoma (NHL). FC results may be hampered by the scarce viability and low cellularity of the specimens. We developed a single-tube FC assay (STA) that included 10 antibodies cocktailed in 8-color labeling, a cell viability dye, and a logical gating strategy to detect NHL in hypocellular samples. The results were correlated with CM and confirmed by histologic or molecular data when available. Using the STA, we detected B-type NHL in 31 out of 103 hypocellular samples (81 FNA and 22 SCE). Of these, 8 were not confirmed by CM and 2 were considered to be only suspicious. The FC-negative samples had a final diagnosis of benign/reactive process (42/72), carcinoma (27/72), or Hodgkin lymphoma (3/72). The STA approach allowed obtainment of maximum immunophenotyping data in specimens containing a low number of cells and a large amount of debris. The information obtained by STA can help cytomorphologists not only to recognize but also to exclude malignant lymphomas. © 2016 S. Karger AG, Basel.

  8. Electrophysiological dynamics reveal distinct processing of stimulus-stimulus and stimulus-response conflicts.

    Science.gov (United States)

    Li, Qi; Wang, Kai; Nan, Weizhi; Zheng, Ya; Wu, Haiyan; Wang, Hongbin; Liu, Xun

    2015-04-01

    The present study examined electroencephalogram profiles on a novel stimulus-response compatibility (SRC) task in order to elucidate the distinct brain mechanisms of stimulus-stimulus (S-S) and stimulus-response (S-R) conflict processing. The results showed that the SRC effects on reaction times (RTs) and N2 amplitudes were additive when both S-S and S-R conflicts existed. We also observed that, for both RTs and N2 amplitudes, the conflict adaptation effects-the reduced SRC effect following an incongruent trial versus a congruent trial-were present only when two consecutive trials involved the same type of conflict. Time-frequency analysis revealed that both S-S and S-R conflicts modulated power in the theta band, whereas S-S conflict additionally modulated power in the alpha and beta bands. In summary, our findings provide insight into the domain-specific conflict processing and the modular organization of cognitive control. Copyright © 2014 Society for Psychophysiological Research.

  9. Estimation of 131J-Jodohippurateclearance by a simplified method using a single plasma sample

    International Nuclear Information System (INIS)

    Botsch, H.; Golde, G.; Kampf, D.

    1980-01-01

    Theoretical volumes calculated from the reciprocal of the plasma concentration of 131 J-Jodohippurate were compared in 95 patients with clearance values calculated by the 2-compartment-method and in 18 patients with conventional PAH-clearance. For estimating Hippurate-clearance from a single blood sampling the most favorable time is 45 min. after injection (r = 0.96; clearance 400/ml/min.: r = 0.98). Clearance values may be derived from the formula: C = 0.4 + 7.26 V - 0.021 x V 2 (V = injected activity/activity per l plasma taken 45 min. after injection). The simplicity, precision and reproducibility of the above mentioned clearance-method is emphasized. (orig.) [de

  10. Single-breath-hold 3-D CINE imaging of the left ventricle using Cartesian sampling.

    Science.gov (United States)

    Wetzl, Jens; Schmidt, Michaela; Pontana, François; Longère, Benjamin; Lugauer, Felix; Maier, Andreas; Hornegger, Joachim; Forman, Christoph

    2018-02-01

    Our objectives were to evaluate a single-breath-hold approach for Cartesian 3-D CINE imaging of the left ventricle with a nearly isotropic resolution of [Formula: see text] and a breath-hold duration of [Formula: see text]19 s against a standard stack of 2-D CINE slices acquired in multiple breath-holds. Validation is performed with data sets from ten healthy volunteers. A Cartesian sampling pattern based on the spiral phyllotaxis and a compressed sensing reconstruction method are proposed to allow 3-D CINE imaging with high acceleration factors. The fully integrated reconstruction uses multiple graphics processing units to speed up the reconstruction. The 2-D CINE and 3-D CINE are compared based on ventricular function parameters, contrast-to-noise ratio and edge sharpness measurements. Visual comparisons of corresponding short-axis slices of 2-D and 3-D CINE show an excellent match, while 3-D CINE also allows reformatting to other orientations. Ventricular function parameters do not significantly differ from values based on 2-D CINE imaging. Reconstruction times are below 4 min. We demonstrate single-breath-hold 3-D CINE imaging in volunteers and three example patient cases, which features fast reconstruction and allows reformatting to arbitrary orientations.

  11. Single cell PCR amplification of diatoms using fresh and preserved samples

    Science.gov (United States)

    Hamilton, Paul B.; Lefebvre, Keely E.; Bull, Roger D.

    2015-01-01

    Single cell Chelex® DNA extraction and nested PCR amplification were used to examine partial gene sequences from natural diatom populations for taxonomic and phylogenetic studies at and above the level of species. DNA was extracted from cells that were either fresh collected or stored in RNAlater. Extractions from Lugol's fixation were also attempted with limited success. Three partial gene sequences (rbcL, 18S, and psbA) were recovered using existing and new primers with a nested or double nested PCR approach with amplification and success rates between 70 and 96%. An rbcL consensus tree grouped morphologically similar specimens and was consistent across the two primary sample treatments: fresh and RNAlater. This tool will greatly enhance the number of microscopic diatom taxa (and potentially other microbes) available for barcoding and phylogenetic studies. The near-term increase in sequence data for diatoms generated via routine single cell extractions and PCR will act as a multiproxy validation of longer-term next generation genomics. PMID:26528252

  12. Brief communication: Is variation in the cranial capacity of the Dmanisi sample too high to be from a single species?

    Science.gov (United States)

    Lee, Sang-Hee

    2005-07-01

    This study uses data resampling to test the null hypothesis that the degree of variation in the cranial capacity of the Dmanisi hominid sample is within the range variation of a single species. The statistical significance of the variation in the Dmanisi sample is examined using simulated distributions based on comparative samples of modern humans, chimpanzees, and gorillas. Results show that it is unlikely to find the maximum difference observed in the Dmanisi sample in distributions of female-female pairs from comparative single-species samples. Given that two sexes are represented, the difference in the Dmanisi sample is not enough to reject the null hypothesis of a single species. Results of this study suggest no compelling reason to invoke multiple taxa to explain variation in the cranial capacity of the Dmanisi hominids. (c) 2004 Wiley-Liss, Inc

  13. Adaptive stimulus optimization for sensory systems neuroscience

    OpenAIRE

    DiMattina, Christopher; Zhang, Kechen

    2013-01-01

    In this paper, we review several lines of recent work aimed at developing practical methods for adaptive on-line stimulus generation for sensory neurophysiology. We consider various experimental paradigms where on-line stimulus optimization is utilized, including the classical optimal stimulus paradigm where the goal of experiments is to identify a stimulus which maximizes neural responses, the iso-response paradigm which finds sets of stimuli giving rise to constant responses, and the system...

  14. Single sample expression-anchored mechanisms predict survival in head and neck cancer.

    Directory of Open Access Journals (Sweden)

    Xinan Yang

    2012-01-01

    Full Text Available Gene expression signatures that are predictive of therapeutic response or prognosis are increasingly useful in clinical care; however, mechanistic (and intuitive interpretation of expression arrays remains an unmet challenge. Additionally, there is surprisingly little gene overlap among distinct clinically validated expression signatures. These "causality challenges" hinder the adoption of signatures as compared to functionally well-characterized single gene biomarkers. To increase the utility of multi-gene signatures in survival studies, we developed a novel approach to generate "personal mechanism signatures" of molecular pathways and functions from gene expression arrays. FAIME, the Functional Analysis of Individual Microarray Expression, computes mechanism scores using rank-weighted gene expression of an individual sample. By comparing head and neck squamous cell carcinoma (HNSCC samples with non-tumor control tissues, the precision and recall of deregulated FAIME-derived mechanisms of pathways and molecular functions are comparable to those produced by conventional cohort-wide methods (e.g. GSEA. The overlap of "Oncogenic FAIME Features of HNSCC" (statistically significant and differentially regulated FAIME-derived genesets representing GO functions or KEGG pathways derived from HNSCC tissue among three distinct HNSCC datasets (pathways:46%, p<0.001 is more significant than the gene overlap (genes:4%. These Oncogenic FAIME Features of HNSCC can accurately discriminate tumors from control tissues in two additional HNSCC datasets (n = 35 and 91, F-accuracy = 100% and 97%, empirical p<0.001, area under the receiver operating characteristic curves = 99% and 92%, and stratify recurrence-free survival in patients from two independent studies (p = 0.0018 and p = 0.032, log-rank. Previous approaches depending on group assignment of individual samples before selecting features or learning a classifier are limited by design to

  15. Gold-FISH: A correlative approach to microscopic imaging of single microbial cells in environmental samples

    Science.gov (United States)

    Schmidt, Hannes; Seki, David; Woebken, Dagmar; Eickhorst, Thilo

    2017-04-01

    Fluorescence in situ hybridization (FISH) is routinely used for the phylogenetic identification, detection, and quantification of single microbial cells environmental microbiology. Oligonucleotide probes that match the 16S rRNA sequence of target organisms are generally applied and the resulting signals are visualized via fluorescence microscopy. Consequently, the detection of the microbial cells of interest is limited by the resolution and the sensitivity of light microscopy where objects smaller than 0.2 µm can hardly be represented. Visualizing microbial cells at magnifications beyond light microscopy, however, can provide information on the composition and potential complexity of microbial habitats - the actual sites of nutrient cycling in soil and sediments. We present a recently developed technique that combines (1) the phylogenetic identification and detection of individual microorganisms by epifluorescence microscopy, with (2) the in situ localization of gold-labelled target cells on an ultrastructural level by SEM. Based on 16S rRNA targeted in situ hybridization combined with catalyzed reporter deposition, a streptavidin conjugate labeled with a fluorescent dye and nanogold particles is introduced into whole microbial cells. A two-step visualization process including an autometallographic enhancement of nanogold particles then allows for either fluorescence or electron microscopy, or a correlative application thereof. We will present applications of the Gold-FISH protocol to samples of marine sediments, agricultural soils, and plant roots. The detection and enumeration of bacterial cells in soil and sediment samples was comparable to CARD-FISH applications via fluorescence microscopy. Examples of microbe-surface interaction analysis will be presented on the basis of bacteria colonizing the rhizoplane of rice roots. In principle, Gold-FISH can be performed on any material to give a snapshot of microbe-surface interactions and provides a promising tool for

  16. Evaluation of an Efficient Method for Training Staff to Implement Stimulus Preference Assessments

    Science.gov (United States)

    Roscoe, Eileen M.; Fisher, Wayne W.

    2008-01-01

    We used a brief training procedure that incorporated feedback and role-play practice to train staff members to conduct stimulus preference assessments, and we used group-comparison methods to evaluate the effects of training. Staff members were trained to implement the multiple-stimulus-without-replacement assessment in a single session and the…

  17. Area G perimeter surface-soil and single-stage water sampling: Environmental surveillance for fiscal year 95. Progress report

    Energy Technology Data Exchange (ETDEWEB)

    Childs, M.; Conrad, R.

    1997-09-01

    ESH-19 personnel collected soil and single-stage water samples around the perimeter of Area G at Los Alamos National Laboratory (LANL) during FY 95 to characterize possible radionuclide movement out of Area G through surface water and entrained sediment runoff. Soil samples were analyzed for tritium, total uranium, isotopic plutonium, americium-241, and cesium-137. The single-stage water samples were analyzed for tritium and plutonium isotopes. All radiochemical data was compared with analogous samples collected during FY 93 and 94 and reported in LA-12986 and LA-13165-PR. Six surface soils were also submitted for metal analyses. These data were included with similar data generated for soil samples collected during FY 94 and compared with metals in background samples collected at the Area G expansion area.

  18. Stimulus conflict triggers behavioral avoidance.

    Science.gov (United States)

    Dignath, David; Eder, Andreas B

    2015-12-01

    According to a recent extension of the conflict-monitoring theory, conflict between two competing response tendencies is registered as an aversive event and triggers a motivation to avoid the source of conflict. In the present study, we tested this assumption. Over five experiments, we examined whether conflict is associated with an avoidance motivation and whether stimulus conflict or response conflict triggers an avoidance tendency. Participants first performed a color Stroop task. In a subsequent motivation test, participants responded to Stroop stimuli with approach- and avoidance-related lever movements. These results showed that Stroop-conflict stimuli increased the frequency of avoidance responses in a free-choice motivation test, and also increased the speed of avoidance relative to approach responses in a forced-choice test. High and low proportions of response conflict in the Stroop task had no effect on avoidance in the motivation test. Avoidance of conflict was, however, obtained even with new conflict stimuli that had not been presented before in a Stroop task, and when the Stroop task was replaced with an unrelated filler task. Taken together, these results suggest that stimulus conflict is sufficient to trigger avoidance.

  19. Poor stimulus discriminability as a common neuropsychological deficit between ADHD and reading ability in young children: a moderated mediation model.

    Science.gov (United States)

    Lúcio, P S; Salum, G A; Rohde, L A; Swardfager, W; Gadelha, A; Vandekerckhove, J; Pan, P M; Polanczyk, G V; do Rosário, M C; Jackowski, A P; Mari, J J; Cogo-Moreira, H

    2017-01-01

    Attention deficit hyperactivity disorder (ADHD) is frequently associated with poorer reading ability; however, the specific neuropsychological domains linking this co-occurrence remain unclear. This study evaluates information-processing characteristics as possible neuropsychological links between ADHD symptoms and RA in a community-based sample of children and early adolescents with normal IQ (⩾70). The participants (n = 1857, aged 6-15 years, 47% female) were evaluated for reading ability (reading single words aloud) and information processing [stimulus discriminability in the two-choice reaction-time task estimated using diffusion models]. ADHD symptoms were ascertained through informant (parent) report using the Development and Well-Being Assessment (DAWBA). Verbal working memory (VWM; digit span backwards), visuospatial working memory (VSWM, Corsi Blocks backwards), sex, socioeconomic status, and IQ were included as covariates. In a moderated mediation model, stimulus discriminability mediated the effect of ADHD on reading ability. This indirect effect was moderated by age such that a larger effect was seen among younger children. The findings support the hypothesis that ADHD and reading ability are linked among young children via a neuropsychological deficit related to stimulus discriminability. Early interventions targeting stimulus discriminability might improve symptoms of inattention/hyperactivity and reading ability.

  20. Stimulus number, duration and intensity encoding in randomly connected attractor networks with synaptic depression

    Directory of Open Access Journals (Sweden)

    Paul eMiller

    2013-05-01

    Full Text Available Randomly connected recurrent networks of excitatory groups of neurons can possess a multitude of attractor states. When the internal excitatory synapses of these networks are depressing, the attractor states can be destabilized with increasing input. This leads to an itinerancy, where with either repeated transient stimuli, or increasing duration of a single stimulus, the network activity advances through sequences of attractor states. We find that the resulting network state, which persists beyond stimulus offset, can encode the number of stimuli presented via a distributed representation of neural activity with non-monotonic tuning curves for most neurons. Increased duration of a single stimulus is encoded via different distributed representations, so unlike an integrator, the network distinguishes separate successive presentations of a short stimulus from a single presentation of a longer stimulus with equal total duration. Moreover, different amplitudes of stimulus cause new, distinct activity patterns, such that changes in stimulus number, duration and amplitude can be distinguished from each other. These properties of the network depend on dynamic depressing synapses, as they disappear if synapses are static. Thus short-term synaptic depression allows a network to store separately the different dynamic properties of a spatially constant stimulus.

  1. Volterra dendritic stimulus processors and biophysical spike generators with intrinsic noise sources.

    Science.gov (United States)

    Lazar, Aurel A; Zhou, Yiyin

    2014-01-01

    We consider a class of neural circuit models with internal noise sources arising in sensory systems. The basic neuron model in these circuits consists of a dendritic stimulus processor (DSP) cascaded with a biophysical spike generator (BSG). The dendritic stimulus processor is modeled as a set of nonlinear operators that are assumed to have a Volterra series representation. Biophysical point neuron models, such as the Hodgkin-Huxley neuron, are used to model the spike generator. We address the question of how intrinsic noise sources affect the precision in encoding and decoding of sensory stimuli and the functional identification of its sensory circuits. We investigate two intrinsic noise sources arising (i) in the active dendritic trees underlying the DSPs, and (ii) in the ion channels of the BSGs. Noise in dendritic stimulus processing arises from a combined effect of variability in synaptic transmission and dendritic interactions. Channel noise arises in the BSGs due to the fluctuation of the number of the active ion channels. Using a stochastic differential equations formalism we show that encoding with a neuron model consisting of a nonlinear DSP cascaded with a BSG with intrinsic noise sources can be treated as generalized sampling with noisy measurements. For single-input multi-output neural circuit models with feedforward, feedback and cross-feedback DSPs cascaded with BSGs we theoretically analyze the effect of noise sources on stimulus decoding. Building on a key duality property, the effect of noise parameters on the precision of the functional identification of the complete neural circuit with DSP/BSG neuron models is given. We demonstrate through extensive simulations the effects of noise on encoding stimuli with circuits that include neuron models that are akin to those commonly seen in sensory systems, e.g., complex cells in V1.

  2. Volterra dendritic stimulus processors and biophysical spike generators with intrinsic noise sources

    Science.gov (United States)

    Lazar, Aurel A.; Zhou, Yiyin

    2014-01-01

    We consider a class of neural circuit models with internal noise sources arising in sensory systems. The basic neuron model in these circuits consists of a dendritic stimulus processor (DSP) cascaded with a biophysical spike generator (BSG). The dendritic stimulus processor is modeled as a set of nonlinear operators that are assumed to have a Volterra series representation. Biophysical point neuron models, such as the Hodgkin-Huxley neuron, are used to model the spike generator. We address the question of how intrinsic noise sources affect the precision in encoding and decoding of sensory stimuli and the functional identification of its sensory circuits. We investigate two intrinsic noise sources arising (i) in the active dendritic trees underlying the DSPs, and (ii) in the ion channels of the BSGs. Noise in dendritic stimulus processing arises from a combined effect of variability in synaptic transmission and dendritic interactions. Channel noise arises in the BSGs due to the fluctuation of the number of the active ion channels. Using a stochastic differential equations formalism we show that encoding with a neuron model consisting of a nonlinear DSP cascaded with a BSG with intrinsic noise sources can be treated as generalized sampling with noisy measurements. For single-input multi-output neural circuit models with feedforward, feedback and cross-feedback DSPs cascaded with BSGs we theoretically analyze the effect of noise sources on stimulus decoding. Building on a key duality property, the effect of noise parameters on the precision of the functional identification of the complete neural circuit with DSP/BSG neuron models is given. We demonstrate through extensive simulations the effects of noise on encoding stimuli with circuits that include neuron models that are akin to those commonly seen in sensory systems, e.g., complex cells in V1. PMID:25225477

  3. Sampling

    CERN Document Server

    Thompson, Steven K

    2012-01-01

    Praise for the Second Edition "This book has never had a competitor. It is the only book that takes a broad approach to sampling . . . any good personal statistics library should include a copy of this book." —Technometrics "Well-written . . . an excellent book on an important subject. Highly recommended." —Choice "An ideal reference for scientific researchers and other professionals who use sampling." —Zentralblatt Math Features new developments in the field combined with all aspects of obtaining, interpreting, and using sample data Sampling provides an up-to-date treat

  4. Poverty of the stimulus revisited.

    Science.gov (United States)

    Berwick, Robert C; Pietroski, Paul; Yankama, Beracah; Chomsky, Noam

    2011-01-01

    A central goal of modern generative grammar has been to discover invariant properties of human languages that reflect "the innate schematism of mind that is applied to the data of experience" and that "might reasonably be attributed to the organism itself as its contribution to the task of the acquisition of knowledge" (Chomsky, 1971). Candidates for such invariances include the structure dependence of grammatical rules, and in particular, certain constraints on question formation. Various "poverty of stimulus" (POS) arguments suggest that these invariances reflect an innate human endowment, as opposed to common experience: Such experience warrants selection of the grammars acquired only if humans assume, a priori, that selectable grammars respect substantive constraints. Recently, several researchers have tried to rebut these POS arguments. In response, we illustrate why POS arguments remain an important source of support for appeal to a priori structure-dependent constraints on the grammars that humans naturally acquire. Copyright © 2011 Cognitive Science Society, Inc.

  5. Detection and mapping of Cannabinoids in single hair samples through rapid derivatization- Matrix-Assisted Laser Desorption Ionization Mass Spectrometry

    OpenAIRE

    Beasley, Emma; Francese, Simona; Bassindale, Thomas

    2016-01-01

    The sample preparation method reported in this work has permitted for the first time the application of Matrix Assisted Laser Desorption Ionization Mass Spectrometry Profiling and Imaging (MALDI-MSP and MALDI-MSI) for the detection and mapping of cannabinoids in a single hair sample. MALDI-MSI analysis of hair samples has recently been suggested as an alternative technique to traditional methods of GC-MS and LC-MS due to simpler sample preparation, the ability to detect a narrower time frame ...

  6. Rational-emotive behavior therapy and the formation of stimulus equivalence classes.

    Science.gov (United States)

    Plaud, J J; Gaither, G A; Weller, L A; Bigwood, S J; Barth, J; von Duvillard, S P

    1998-08-01

    Stimulus equivalence is a behavioral approach to analyzing the "meaning" of stimulus sets and has an implication for clinical psychology. The formation of three-member (A --> B --> C) stimulus equivalence classes was used to investigate the effects of three different sets of sample and comparison stimuli on emergent behavior. The three stimulus sets were composed of Rational-Emotive Behavior Therapy (REBT)-related words, non-REBT emotionally charged words, and a third category of neutral words composed of flower labels. Sixty-two women and men participated in a modified matching-to-sample experiment. Using a mixed cross-over design, and controlling for serial order effects, participants received conditional training and emergent relationship training in the three stimulus set conditions. Results revealed a significant interaction between the formation of stimulus equivalence classes and stimulus meaning, indicating consistently biased responding in favor of reaching criterion responding more slowly for REBT-related and non-REBT emotionally charged words. Results were examined in the context of an analysis of the importance of stimulus meaning on behavior and the relation of stimulus meaning to behavioral and cognitive theories, with special appraisal given to the influence of fear-related discriminative stimuli on behavior.

  7. Field testing of collection cards for Cannabis sativa samples with a single hexanucleotide DNA marker.

    Science.gov (United States)

    Allgeier, Lindsay; Hemenway, John; Shirley, Nicholas; LaNier, Tommy; Coyle, Heather Miller

    2011-09-01

    The validity and feasibility of using DNA collection cards in the field for preservation and analysis of Cannabis sativa genotypes were investigated using a highly specific hexanucleotide marker. Collection cards were submitted to the National Marijuana Initiative, which selectively trained and managed the collection of specific types of samples from a variety of participating agencies. Samples collected at seizure sites included fresh marijuana leaf samples, dried "dispensary" samples, U.S. border seizures, and hashish. Using a standardized PCR kit with custom-labeled oligonucleotide primers specific to marijuana, collection cards produced eight genotypes and 13 different alleles, extremely low baselines, and no cross-reactivity with control plant species. Results were produced from all sample types with the exception of hashish. Plant DNA collection cards represent an easily implementable method for the genetic identification and relatedness of C. sativa street and grow site-seized samples with applications for databasing and market disruption. © 2011 American Academy of Forensic Sciences.

  8. Inert gases in a terra sample - Measurements in six grain-size fractions and two single particles from Lunar 20.

    Science.gov (United States)

    Heymann, D.; Lakatos, S.; Walton, J. R.

    1973-01-01

    Review of the results of inert gas measurements performed on six grain-size fractions and two single particles from four samples of Luna 20 material. Presented and discussed data include the inert gas contents, element and isotope systematics, radiation ages, and Ar-36/Ar-40 systematics.

  9. Label-free isolation and deposition of single bacterial cells from heterogeneous samples for clonal culturing

    OpenAIRE

    J. Riba; T. Gleichmann; S. Zimmermann; R. Zengerle; P. Koltay

    2016-01-01

    The isolation and analysis of single prokaryotic cells down to 1??m and less in size poses a special challenge and requires micro-engineered devices to handle volumes in the picoliter to nanoliter range. Here, an advanced Single-Cell Printer (SCP) was applied for automated and label-free isolation and deposition of bacterial cells encapsulated in 35?pl droplets by inkjet-like printing. To achieve this, dispenser chips to generate micro droplets have been fabricated with nozzles 20??m in size....

  10. Stimulus Probability Effects in Absolute Identification

    Science.gov (United States)

    Kent, Christopher; Lamberts, Koen

    2016-01-01

    This study investigated the effect of stimulus presentation probability on accuracy and response times in an absolute identification task. Three schedules of presentation were used to investigate the interaction between presentation probability and stimulus position within the set. Data from individual participants indicated strong effects of…

  11. Single point aerosol sampling: Evaluation of mixing and probe performance in a nuclear stack

    Energy Technology Data Exchange (ETDEWEB)

    Rodgers, J.C.; Fairchild, C.I.; Wood, G.O. [Los Alamos National Laboratory, NM (United States)] [and others

    1995-02-01

    Alternative Reference Methodologies (ARMs) have been developed for sampling of radionuclides from stacks and ducts that differ from the methods required by the U.S. EPA. The EPA methods are prescriptive in selection of sampling locations and in design of sampling probes whereas the alternative methods are performance driven. Tests were conducted in a stack at Los Alamos National Laboratory to demonstrate the efficacy of the ARMs. Coefficients of variation of the velocity tracer gas, and aerosol particle profiles were determined at three sampling locations. Results showed numerical criteria placed upon the coefficients of variation by the ARMs were met at sampling stations located 9 and 14 stack diameters from flow entrance, but not at a location that is 1.5 diameters downstream from the inlet. Experiments were conducted to characterize the transmission of 10 {mu}m aerodynamic equivalent diameter liquid aerosol particles through three types of sampling probes. The transmission ratio (ratio of aerosol concentration at the probe exit plane to the concentration in the free stream) was 107% for a 113 L/min (4-cfm) anisokinetic shrouded probe, but only 20% for an isokinetic probe that follows the EPA requirements. A specially designed isokinetic probe showed a transmission ratio of 63%. The shrouded probe performance would conform to the ARM criteria; however, the isokinetic probes would not.

  12. A single lysis solution for the analysis of tissue samples by different proteomic technologies

    DEFF Research Database (Denmark)

    Gromov, P.; Celis, J.E.; Gromova, I.

    2008-01-01

    -based proteomics (reverse-phase lysate arrays or direct antibody arrays), allowing the direct comparison of qualitative and quantitative data yielded by these technologies when applied to the same samples. The usefulness of the CLB1 solution for gel-based proteomics was further established by 2D PAGE analysis...... taken place in molecular biology, cell biology and genomics there is a pressing need to accelerate the translation of basic discoveries into clinical applications. This need, compounded by mounting evidence that cellular model systems are unable to fully recapitulate all biological aspects of human...... dissease, is driving scientists to increasingly use clinically relevant samples for biomarker and target discovery. Tissues are heterogeneous and as a result optimization of sample preparation is critical for generating accurate, representative, and highly reproducible quantitative data. Although a large...

  13. Measurement of glomerular filtration rate in adults: accuracy of five single-sample plasma clearance methods

    DEFF Research Database (Denmark)

    Rehling, M; Rabøl, A

    1989-01-01

    After an intravenous injection of a tracer that is removed from the body solely by filtration in the kidneys, the glomerular filtration rate (GFR) can be determined from its plasma clearance. The method requires a great number of blood samples but collection of urine is not needed. In the present...

  14. Determination of burial dose in incompletely bleached fluvial samples using single grains of quartz

    DEFF Research Database (Denmark)

    Thomsen, Kristina Jørkov; Murray, A.S.; Bøtter-Jensen, Lars

    2007-01-01

    -bleached and gamma-irradiated samples. We show that there is a linear relationship between the over-dispersion and the mean dose. Knowing this uncertainty relationship enables us to estimate the burial dose by comparing the predicted uncertainty on the running mean with that calculated from actual dispersion. (c...

  15. Quantitative in-situ TEM nanotensile testing of single crystal Ni facilitated by a new sample preparation approach.

    Science.gov (United States)

    Samaeeaghmiyoni, Vahid; Idrissi, Hosni; Groten, Jonas; Schwaiger, Ruth; Schryvers, Dominique

    2017-03-01

    Twin-jet electro-polishing and Focused Ion Beam (FIB) were combined to produce small size Nickel single crystal specimens for quantitative in-situ nanotensile experiments in the transmission electron microscope. The combination of these techniques allows producing samples with nearly defect-free zones in the centre in contrast to conventional FIB-prepared samples. Since TEM investigations can be performed on the electro-polished samples prior to in-situ TEM straining, specimens with desired crystallographic orientation and initial microstructure can be prepared. The present results reveal a dislocation nucleation-controlled plasticity, in which small loops induced by FIB near the edges of the samples play a central role. Copyright © 2016 Elsevier Ltd. All rights reserved.

  16. A proposal for the measurement of Rashba and Dresselhaus spin–orbit interaction strengths in a single sample

    International Nuclear Information System (INIS)

    Maiti, Santanu K.; Sil, Shreekantha; Chakrabarti, Arunava

    2012-01-01

    We establish an exact analytical treatment for the determination of the strengths of the Rashba and Dresselhaus spin–orbit interactions in a single sample by measuring persistent spin current. A hidden symmetry is exploited in the Hamiltonian to show that the spin current vanishes when the strength of the Dresselhaus interaction becomes equal to the strength of the Rashba term. The results are sustained even in the presence of disorder and thus an experiment in this regard will be challenging. -- Highlights: ► An exact analytical treatment is given for the measurement of spin–orbit interaction strengths in a single sample. ► Persistent spin current is calculated. ► Our present analysis gives us confidence to propose an experiment in this line.

  17. Adaptive stimulus optimization for sensory systems neuroscience.

    Science.gov (United States)

    DiMattina, Christopher; Zhang, Kechen

    2013-01-01

    In this paper, we review several lines of recent work aimed at developing practical methods for adaptive on-line stimulus generation for sensory neurophysiology. We consider various experimental paradigms where on-line stimulus optimization is utilized, including the classical optimal stimulus paradigm where the goal of experiments is to identify a stimulus which maximizes neural responses, the iso-response paradigm which finds sets of stimuli giving rise to constant responses, and the system identification paradigm where the experimental goal is to estimate and possibly compare sensory processing models. We discuss various theoretical and practical aspects of adaptive firing rate optimization, including optimization with stimulus space constraints, firing rate adaptation, and possible network constraints on the optimal stimulus. We consider the problem of system identification, and show how accurate estimation of non-linear models can be highly dependent on the stimulus set used to probe the network. We suggest that optimizing stimuli for accurate model estimation may make it possible to successfully identify non-linear models which are otherwise intractable, and summarize several recent studies of this type. Finally, we present a two-stage stimulus design procedure which combines the dual goals of model estimation and model comparison and may be especially useful for system identification experiments where the appropriate model is unknown beforehand. We propose that fast, on-line stimulus optimization enabled by increasing computer power can make it practical to move sensory neuroscience away from a descriptive paradigm and toward a new paradigm of real-time model estimation and comparison.

  18. Isolation of RNA from tumor samples: single-step guanidinium acid-phenol method.

    Science.gov (United States)

    Robertson, Naomi; Leek, Russell

    2006-01-01

    The guanidinium acid-phenol method of RNA extraction is relatively fast (4 h) and is useful for the processing of large numbers of samples, without the need for ultracentrifugation. This protocol produces total RNA that includes ribosomal, transfer, and messenger RNA. This high-quality RNA is suitable for Northern blot analysis, dot-blot hybridization, poly (A) RNA selection, in vitro translation, cDNA library construction, reverse transcriptase-polymerase chain reaction, ribonuclease protection assay, and primer extension experiments.

  19. Single blood-Hg samples can result in exposure misclassification: temporal monitoring within the Japanese community (United States

    Directory of Open Access Journals (Sweden)

    Tsuchiya Ami

    2012-06-01

    Full Text Available Abstract Background The most prominent non-occupational source of exposure to methylmercury is the consumption of fish. In this study we examine a fish consuming population to determine the extent of temporal exposure and investigate the extent to which single time estimates of methylmercury exposure based on blood-Hg concentration can provide reliable estimates of longer-term average exposure. Methods Blood-mercury levels were obtained from a portion of the Arsenic Mercury Intake Biometric Study (AMIBS cohort. Specifically, 56 Japanese women residing in the Puget Sound area of Washington State, US were sampled on three occasions across a one-year period. Results An average of 135 days separated samples, with mean blood-mercury levels for the visits being 5.1, 6.6 and 5.0 μg/l and geometric means being 2.7, 4.5 and 3.1 μg/l. The blood-mercury levels in this group exceed national averages with geometric means for two of the visits being between the 90th and 95th percentiles of nationally observed levels and the lowest geometric mean being between the 75th and 90th percentile. Group means were not significantly different across sampling periods suggesting that exposure of combined subjects remained relatively constant. Comparing intra-individual results over time did not reveal a strong correlation among visits (r = 0.19, 0.50, 0.63 between 1st and 2nd, 2nd and 3rd, and 1st and 3rd sample results, respectively. In comparing blood-mercury levels across two sampling interval combinations (1st and 2nd, 2nd and 3rd, and 1st and 3rd visits, respectively, 58% (n = 34, 53% (n = 31 and 29% (n = 17 of the individuals had at least a 100% difference in blood-Hg levels. Conclusions Point estimates of blood-mercury, when compared with three sample averages, may not reflect temporal variability and individual exposures estimated on the basis of single blood samples should be treated with caution as indicators of long-term exposure

  20. A method for multiple sequential analyses of macrophage functions using a small single cell sample

    Directory of Open Access Journals (Sweden)

    F.R.F. Nascimento

    2003-09-01

    Full Text Available Microbial pathogens such as bacillus Calmette-Guérin (BCG induce the activation of macrophages. Activated macrophages can be characterized by the increased production of reactive oxygen and nitrogen metabolites, generated via NADPH oxidase and inducible nitric oxide synthase, respectively, and by the increased expression of major histocompatibility complex class II molecules (MHC II. Multiple microassays have been developed to measure these parameters. Usually each assay requires 2-5 x 10(5 cells per well. In some experimental conditions the number of cells is the limiting factor for the phenotypic characterization of macrophages. Here we describe a method whereby this limitation can be circumvented. Using a single 96-well microassay and a very small number of peritoneal cells obtained from C3H/HePas mice, containing as little as <=2 x 10(5 macrophages per well, we determined sequentially the oxidative burst (H2O2, nitric oxide production and MHC II (IAk expression of BCG-activated macrophages. More specifically, with 100 µl of cell suspension it was possible to quantify H2O2 release and nitric oxide production after 1 and 48 h, respectively, and IAk expression after 48 h of cell culture. In addition, this microassay is easy to perform, highly reproducible and more economical.

  1. Estimation of effective renal plasma flow in children by use of a single plasma sample after injection of orthoiodohippurate

    International Nuclear Information System (INIS)

    Tauxe, W.N.; Hagge, W.; Stickler, G.B.

    1975-01-01

    Estimates of effective renal plasma flow (ERPF) in adults have been greatly simplified by the use of recently developed regression equations based on a single plasma concentration of radioiodinated orthoiodohippurate (OIH) obtained 44 min after a single intravenous injection of the material. The paper reports similar equations for the prediction of ERPF in children. Studies were made in 30 children of both sexes, aged 4 to 16 years, with a wide variety of renal diseases. A single intravenous injection of labelled OIH was made and plasma was sampled at 10, 15, 20, 25, 30, 40, 50 and 60 min after injection. Plasma concentration curves were analysed by the conventional two-compartment analysis technique (Sapirstein, Matthews) and ERPF was computed from them. In addition to ERPF calculations, sizes of the two volumes of distribution (V 1 and V 2 ), intercompartmental flow rates and fractional rate constants were also calculated. Surface area (SA) was calculated from the DuBois height-weight regression formula. Reciprocals of the OIH plasma concentration in terms of per cent injected dose per litre were calculated at each sampling time; this reciprocal is designated x. These values at each sampling time were plotted against ERPF and regression equations and residual error (Sy.x) were calculated. The optimal sampling time was found to occur at 53 min and the corresponding linear regression equation was 19.33 + 3.87x with a Sy.x value of 36 ml. This compares with an optimal sampling time in adults of 44 min. The mean initial volume of distribution (V 1 ) was found to be 5.3 litres and the mean V 2 was found to be 6.8 litres. In contrast to findings in the previous study in adults these volumes were found to correlate well with SA. A mean intercompartmental flow rate of 276 ml/min was found. No correlation between this value and clinical diagnosis was found. The relationship of the concentration reciprocal and plasma flow was a linear one instead of the polynomial one

  2. Testing the accuracy of a Bayesian central-dose model for single-grain OSL, using known-age samples

    DEFF Research Database (Denmark)

    Guerin, Guillaume; Combès, Benoit; Lahaye, Christelle

    2015-01-01

    remains a difficult task, given the typically considerable dispersion in equivalent dose values measured by OSL - and the numerous sources of such dispersion in measurements. Here, we present the study of 19 samples for which independent age control is available, and whose ages range from 2 to 46ka. Based......-grain OSL and reference ages is about twice as large for the standard approach (12%) as with the Bayesian model (7%). Statistical tests show that, based on our (limited) dataset, the difference between the two models seems to be significant for samples in the age range 4-46ka. Finally, the influence...... on multi-grain OSL age estimates, these samples are presumed to have been both well-bleached at burial, and unaffected by mixing after deposition. Two ways of estimating single-grain ages are then compared: the standard approach on the one hand, consisting of applying the Central Age Model to De values...

  3. Proton-induced single event upset characterisation of a 1 giga-sample per second analog to digital converter

    International Nuclear Information System (INIS)

    Reed, R.A.; Marshall, P.W.; Carts, M.A.

    1999-01-01

    The SPT7760 is an analog to digital converter that is used in satellite for digital processing. In this paper we describe the characterization and analysis of proton-induced single event upsets (SEU) for the SPT7760 operating at sample rates from 125 Msps (Mega-samples per second) to 1 Gsps. The SEU cross-section has been measured as a function of sample rate for various input levels. The data collected is clearly non-linear for all cases. The data shows that this device has a relative low cross-section for proton-induced SEUs and remains functional at a proton dose of 580 krad (Si). (A.C.)

  4. Occlusion for stimulus deprivation amblyopia

    Science.gov (United States)

    Antonio-Santos, Aileen; Vedula, Satyanarayana S; Hatt, Sarah R; Powell, Christine

    2014-01-01

    Background Stimulus deprivation amblyopia (SDA) develops due to an obstruction to the passage of light secondary to a condition such as cataract. The obstruction prevents formation of a clear image on the retina. SDA can be resistant to treatment, leading to poor visual prognosis. SDA probably constitutes less than 3% of all amblyopia cases, although precise estimates of prevalence are unknown. In developed countries, most patients present under the age of one year; in less developed parts of the world patients are likely to be older at the time of presentation. The mainstay of treatment is removal of the cataract and then occlusion of the better-seeing eye, but regimens vary, can be difficult to execute, and traditionally are believed to lead to disappointing results. Objectives Our objective was to evaluate the effectiveness of occlusion therapy for SDA in an attempt to establish realistic treatment outcomes. Where data were available, we also planned to examine evidence of any dose response effect and to assess the effect of the duration, severity, and causative factor on the size and direction of the treatment effect. Search methods We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2013, Issue 9), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to October 2013), EMBASE (January 1980 to October 2013), the Latin American and Caribbean Literature on Health Sciences (LILACS) (January 1982 to October 2013), PubMed (January 1946 to October 2013), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 28 October 2013. Selection criteria We planned

  5. The AlSi10Mg samples produced by selective laser melting: single track, densification, microstructure and mechanical behavior

    International Nuclear Information System (INIS)

    Wei, Pei; Wei, Zhengying; Chen, Zhen; Du, Jun; He, Yuyang; Li, Junfeng; Zhou, Yatong

    2017-01-01

    Highlights: • The thermal behavior of AlSi10Mg molten pool was analyzed. • The SLM-processed sample with a relatively low surface roughness was obtained. • Effects of parameters on surface topography of scan track were investigated. • Effects of parameters on microstructure of parts were investigated. • Optimum processing parameters for AlSi10Mg SLM was obtained. - Abstract: This densification behavior and attendant microstructural characteristics of the selective laser melting (SLM) processed AlSi10Mg alloy affected by the processing parameters were systematically investigated. The samples with a single track were produced by SLM to study the influences of laser power and scanning speed on the surface morphologies of scan tracks. Additionally, the bulk samples were produced to investigate the influence of the laser power, scanning speed, and hatch spacing on the densification level and the resultant microstructure. The experimental results showed that the level of porosity of the SLM-processed samples was significantly governed by energy density of laser beam and the hatch spacing. The tensile properties of SLM-processed samples and the attendant fracture surface can be enhanced by decreasing the level of porosity. The microstructure of SLM-processed samples consists of supersaturated Al-rich cellular structure along with eutectic Al/Si situated at the cellular boundaries. The Si content in the cellular boundaries increases with increasing the laser power and decreasing the scanning speed. The hardness of SLM-processed samples was significantly improved by this fine microstructure compared with the cast samples. Moreover, the hardness of SLM-processed samples at overlaps was lower than the hardness observed at track cores.

  6. The AlSi10Mg samples produced by selective laser melting: single track, densification, microstructure and mechanical behavior

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Pei; Wei, Zhengying, E-mail: zywei@mail.xjtu.edu.cn; Chen, Zhen; Du, Jun; He, Yuyang; Li, Junfeng; Zhou, Yatong

    2017-06-30

    Highlights: • The thermal behavior of AlSi10Mg molten pool was analyzed. • The SLM-processed sample with a relatively low surface roughness was obtained. • Effects of parameters on surface topography of scan track were investigated. • Effects of parameters on microstructure of parts were investigated. • Optimum processing parameters for AlSi10Mg SLM was obtained. - Abstract: This densification behavior and attendant microstructural characteristics of the selective laser melting (SLM) processed AlSi10Mg alloy affected by the processing parameters were systematically investigated. The samples with a single track were produced by SLM to study the influences of laser power and scanning speed on the surface morphologies of scan tracks. Additionally, the bulk samples were produced to investigate the influence of the laser power, scanning speed, and hatch spacing on the densification level and the resultant microstructure. The experimental results showed that the level of porosity of the SLM-processed samples was significantly governed by energy density of laser beam and the hatch spacing. The tensile properties of SLM-processed samples and the attendant fracture surface can be enhanced by decreasing the level of porosity. The microstructure of SLM-processed samples consists of supersaturated Al-rich cellular structure along with eutectic Al/Si situated at the cellular boundaries. The Si content in the cellular boundaries increases with increasing the laser power and decreasing the scanning speed. The hardness of SLM-processed samples was significantly improved by this fine microstructure compared with the cast samples. Moreover, the hardness of SLM-processed samples at overlaps was lower than the hardness observed at track cores.

  7. Misspecifications of stimulus presentation durations in experimental psychology: a systematic review of the psychophysics literature.

    Science.gov (United States)

    Elze, Tobias

    2010-09-29

    In visual psychophysics, precise display timing, particularly for brief stimulus presentations, is often required. The aim of this study was to systematically review the commonly applied methods for the computation of stimulus durations in psychophysical experiments and to contrast them with the true luminance signals of stimuli on computer displays. In a first step, we systematically scanned the citation index Web of Science for studies with experiments with stimulus presentations for brief durations. Articles which appeared between 2003 and 2009 in three different journals were taken into account if they contained experiments with stimuli presented for less than 50 milliseconds. The 79 articles that matched these criteria were reviewed for their method of calculating stimulus durations. For those 75 studies where the method was either given or could be inferred, stimulus durations were calculated by the sum of frames (SOF) method. In a second step, we describe the luminance signal properties of the two monitor technologies which were used in the reviewed studies, namely cathode ray tube (CRT) and liquid crystal display (LCD) monitors. We show that SOF is inappropriate for brief stimulus presentations on both of these technologies. In extreme cases, SOF specifications and true stimulus durations are even unrelated. Furthermore, the luminance signals of the two monitor technologies are so fundamentally different that the duration of briefly presented stimuli cannot be calculated by a single method for both technologies. Statistics over stimulus durations given in the reviewed studies are discussed with respect to different duration calculation methods. The SOF method for duration specification which was clearly dominating in the reviewed studies leads to serious misspecifications particularly for brief stimulus presentations. We strongly discourage its use for brief stimulus presentations on CRT and LCD monitors.

  8. Volterra dendritic stimulus processors and biophysical spike generators with intrinsic noise sources

    Directory of Open Access Journals (Sweden)

    Aurel A Lazar

    2014-09-01

    Full Text Available We consider a class of neural circuit models with internal noise sources arising in sensory systems. The basic neuron model in these circuits consists of a nonlinear dendritic stimulus processor (DSP cascaded with a biophysical spike generator (BSG. The nonlinear dendritic processor is modeled as a set of nonlinear operators that are assumed to have a Volterra series representation. Biophysical point neuron models, such as the Hodgkin-Huxley neuron, are used to model the spike generator. We address the question of how intrinsic noise sources affect the precision in encoding and decoding of sensory stimuli and the functional identification of its sensory circuits.We investigate two intrinsic noise sources arising (i in the active dendritic trees underlying the DSPs, and (ii in the ion channels of the BSGs. Noise in dendritic stimulus processing arises from a combined effect of variability in synaptic transmission and dendritic interactions. Channel noise arises in the BSGs due to the fluctuation of the number of the active ion channels. Using a stochastic differential equations formalism we show that encoding with a neuron model consisting of a nonlinear DSP cascaded with a BSG with intrinsic noise sources can be treated as generalized sampling with noisy measurements.For single-input multi-output neural circuit models with feedforward, feedback and cross-feedback DSPs cascaded with BSGs we theoretically analyze the effect of noise sources on stimulus decoding. Building on a key duality property, the effect of noise parameters on the precision of the functional identification of the complete neural circuit with DSP/BSG neuron models is given. We demonstrate through extensive simulations the effects of noise on encoding stimuli with circuits that include neuron models that are akin to those commonly seen in sensory systems, e.g., complex cells in V1.

  9. Sequence-specific detection of different strains of LCMV in a single sample using tentacle probes.

    Science.gov (United States)

    Franco, Lina S; Holechek, Susan A; Caplan, Michael R; Blattman, Joseph N

    2017-10-13

    Virus infections often result in quasispecies of viral strains that can have dramatic impacts on disease outcomes. However, sequencing of viruses to determine strain composition is time consuming and often cost-prohibitive. Rapid, cost-effective methods are needed for accurate measurement of virus diversity to understand virus evolution and can be useful for experimental systems. We have developed a novel molecular method for sequence-specific detection of RNA virus genetic variants called Tentacle Probes. The probes are modified molecular beacons that have dramatically improved false positive rates and specificity in routine qPCR. To validate this approach, we have designed Tentacle Probes for two different strains of Lymphocytic Choriomeningitis Virus (LCMV) that differ by only 3 nucleotide substitutions, the parental Armstrong and the more virulent Clone-13 strain. One of these mutations is a missense mutation in the receptor protein GP1 that leads to the Armstrong strain to cause an acute infection and Clone-13 to cause a chronic infection instead. The probes were designed using thermodynamic calculations for hybridization between target or non-target sequences and the probe. Using this approach, we were able to distinguish these two strains of LCMV individually by a single nucleotide mutation. The assay showed high reproducibility among different concentrations of viral cDNA, as well as high specificity and sensitivity, especially for the Clone-13 Tentacle Probe. Furthermore, in virus mixing experiments we were able to detect less than 10% of Clone-13 cDNA diluted in Armstrong cDNA. Thus, we have developed a fast, cost-effective approach for identifying Clone-13 strain in a mix of other LCMV strains.

  10. Expectancy bias in a selective conditioning procedure: trait anxiety increases the threat value of a blocked stimulus

    NARCIS (Netherlands)

    Boddez, Y.; Vervliet, B.; Baeyens, F.; Lauwers, S.; Hermans, D.; Beckers, T.

    2012-01-01

    Background and Objectives In a blocking procedure, a single conditioned stimulus (CS) is paired with an unconditioned stimulus (US), such as electric shock, in the first stage. During the subsequent stage, the CS is presented together with a second CS and this compound is followed by the same US.

  11. An in vitro tag-and-modify protein sample generation method for single-molecule fluorescence resonance energy transfer.

    Science.gov (United States)

    Hamadani, Kambiz M; Howe, Jesse; Jensen, Madeleine K; Wu, Peng; Cate, Jamie H D; Marqusee, Susan

    2017-09-22

    Biomolecular systems exhibit many dynamic and biologically relevant properties, such as conformational fluctuations, multistep catalysis, transient interactions, folding, and allosteric structural transitions. These properties are challenging to detect and engineer using standard ensemble-based techniques. To address this drawback, single-molecule methods offer a way to access conformational distributions, transient states, and asynchronous dynamics inaccessible to these standard techniques. Fluorescence-based single-molecule approaches are parallelizable and compatible with multiplexed detection; to date, however, they have remained limited to serial screens of small protein libraries. This stems from the current absence of methods for generating either individual dual-labeled protein samples at high throughputs or protein libraries compatible with multiplexed screening platforms. Here, we demonstrate that by combining purified and reconstituted in vitro translation, quantitative unnatural amino acid incorporation via AUG codon reassignment, and copper-catalyzed azide-alkyne cycloaddition, we can overcome these challenges for target proteins that are, or can be, methionine-depleted. We present an in vitro parallelizable approach that does not require laborious target-specific purification to generate dual-labeled proteins and ribosome-nascent chain libraries suitable for single-molecule FRET-based conformational phenotyping. We demonstrate the power of this approach by tracking the effects of mutations, C-terminal extensions, and ribosomal tethering on the structure and stability of three protein model systems: barnase, spectrin, and T4 lysozyme. Importantly, dual-labeled ribosome-nascent chain libraries enable single-molecule co-localization of genotypes with phenotypes, are well suited for multiplexed single-molecule screening of protein libraries, and should enable the in vitro directed evolution of proteins with designer single-molecule conformational

  12. A review of single-sample-based models and other approaches for radiocarbon dating of dissolved inorganic carbon in groundwater

    Science.gov (United States)

    Han, L. F; Plummer, Niel

    2016-01-01

    Numerous methods have been proposed to estimate the pre-nuclear-detonation 14C content of dissolved inorganic carbon (DIC) recharged to groundwater that has been corrected/adjusted for geochemical processes in the absence of radioactive decay (14C0) - a quantity that is essential for estimation of radiocarbon age of DIC in groundwater. The models/approaches most commonly used are grouped as follows: (1) single-sample-based models, (2) a statistical approach based on the observed (curved) relationship between 14C and δ13C data for the aquifer, and (3) the geochemical mass-balance approach that constructs adjustment models accounting for all the geochemical reactions known to occur along a groundwater flow path. This review discusses first the geochemical processes behind each of the single-sample-based models, followed by discussions of the statistical approach and the geochemical mass-balance approach. Finally, the applications, advantages and limitations of the three groups of models/approaches are discussed.The single-sample-based models constitute the prevailing use of 14C data in hydrogeology and hydrological studies. This is in part because the models are applied to an individual water sample to estimate the 14C age, therefore the measurement data are easily available. These models have been shown to provide realistic radiocarbon ages in many studies. However, they usually are limited to simple carbonate aquifers and selection of model may have significant effects on 14C0 often resulting in a wide range of estimates of 14C ages.Of the single-sample-based models, four are recommended for the estimation of 14C0 of DIC in groundwater: Pearson's model, (Ingerson and Pearson, 1964; Pearson and White, 1967), Han & Plummer's model (Han and Plummer, 2013), the IAEA model (Gonfiantini, 1972; Salem et al., 1980), and Oeschger's model (Geyh, 2000). These four models include all processes considered in single-sample-based models, and can be used in different ranges of

  13. A safety equipment list for rotary mode core sampling systems operation in single shell flammable gas tanks

    International Nuclear Information System (INIS)

    SMALLEY, J.L.

    1999-01-01

    This document identifies all interim safety equipment to be used for rotary mode core sampling of single-shell flammable gas tanks utilizing Rotary Mode Core Sampling systems (RMCS). This document provides the safety equipment for RMCS trucks HO-68K-4600, HO-68K-4647, trucks three and four respectively, and associated equipment. It is not intended to replace or supersede WHC-SD-WM-SEL-023, (Kelly 1991), or WHC-SD-WM-SEL-032, (Corbett 1994), which classifies 80-68K-4344 and HO-68K-4345 respectively. The term ''safety equipment'' refers to safety class (SC) and safety significant (SS) equipment, where equipment refers to structures, systems and components (SSC's). The identification of safety equipment in this document is based on the credited design safety features and analysis contained in the Authorization Basis (AB) for rotary mode core sampling operations in single-shell flammable gas tanks. This is an interim safety classification since the AB is interim. This document will be updated to reflect the final RMCS equipment safety classification designations upon completion of a final AB which will be implemented with the release of the Final Safety Analysis Report (FSAR)

  14. Frequency of single nucleotide polymorphisms of some immune response genes in a population sample from São Paulo, Brazil

    Directory of Open Access Journals (Sweden)

    Léa Campos de Oliveira

    2011-09-01

    Full Text Available Objective: To present the frequency of single nucleotide polymorphismsof a few immune response genes in a population sample from SãoPaulo City (SP, Brazil. Methods: Data on allele frequencies ofknown polymorphisms of innate and acquired immunity genes werepresented, the majority with proven impact on gene function. Datawere gathered from a sample of healthy individuals, non-HLA identicalsiblings of bone marrow transplant recipients from the Hospital dasClínicas da Faculdade de Medicina da Universidade de São Paulo,obtained between 1998 and 2005. The number of samples variedfor each single nucleotide polymorphism analyzed by polymerasechain reaction followed by restriction enzyme cleavage. Results:Allele and genotype distribution of 41 different gene polymorphisms,mostly cytokines, but also including other immune response genes,were presented. Conclusion: We believe that the data presentedhere can be of great value for case-control studies, to define whichpolymorphisms are present in biologically relevant frequencies and toassess targets for therapeutic intervention in polygenic diseases witha component of immune and inflammatory responses.

  15. A Stimulus Sampling Theory of Letter Identity and Order

    Science.gov (United States)

    Norris, Dennis; Kinoshita, Sachiko; van Casteren, Maarten

    2010-01-01

    Early on during word recognition, letter positions are not accurately coded. Evidence for this comes from transposed-letter (TL) priming effects, in which letter strings generated by transposing two adjacent letters (e.g., "jugde") produce large priming effects, more than primes with the letters replaced in the corresponding position (e.g.,…

  16. Evaluation of mixing downstream of tees in duct systems with respect to single point representative air sampling.

    Science.gov (United States)

    Kim, Taehong; O'Neal, Dennis L; Ortiz, Carlos

    2006-09-01

    Air duct systems in nuclear facilities must be monitored with continuous sampling in case of an accidental release of airborne radionuclides. The purpose of this work is to identify the air sampling locations where the velocity and contaminant concentrations fall below the 20% coefficient of variation required by the American National Standards Institute/Health Physics Society N13.1-1999. Experiments of velocity and tracer gas concentration were conducted on a generic "T" mixing system which included combinations of three sub ducts, one main duct, and air velocities from 0.5 to 2 m s (100 to 400 fpm). The experimental results suggest that turbulent mixing provides the accepted velocity coefficients of variation after 6 hydraulic diameters downstream of the T-junction. About 95% of the cases achieved coefficients of variation below 10% by 6 hydraulic diameters. However, above a velocity ratio (velocity in the sub duct/velocity in the main duct) of 2, velocity profiles were uniform in a shorter distance downstream of the T-junction as the velocity ratio went up. For the tracer gas concentration, the distance needed for the coefficients of variation to drop 20% decreased with increasing velocity ratio due to the sub duct airflow momentum. The results may apply to other duct systems with similar geometries and, ultimately, be a basis for selecting a proper sampling location under the requirements of single point representative sampling.

  17. Single-layer centrifugation separates spermatozoa from diploid cells in epididymal samples from gray wolves, Canis lupus (L.).

    Science.gov (United States)

    Muñoz-Fuentes, Violeta; Linde Forsberg, Catharina; Vilà, Carles; Morrell, Jane M

    2014-09-15

    Sperm samples may be used for assisted reproductive technologies (e.g., farmed or endangered species) or as a source of haploid DNA or sperm-specific RNA. When ejaculated spermatozoa are not available or are very difficult to obtain, as is the case for most wild endangered species, the epididymides of dead animals (e.g., animals that have been found dead, shot by hunters or poachers, or that that require euthanasia in zoological collections) can be used as a source of sperm. Such epididymal sperm samples are usually contaminated with cellular debris, erythrocytes, leukocytes, and sometimes also bacteria. These contaminants may be sources of reactive oxygen species that damage spermatozoa during freezing or contribute undesired genetic material from diploid cells. We used single-layer centrifugation through a colloid formulation, Androcoll-C, to successfully separate wolf epididymal spermatozoa from contaminating cells and cellular debris in epididymal samples harvested from carcasses. Such a procedure may potentially be applied to epididymal sperm samples from other species. Copyright © 2014 Elsevier Inc. All rights reserved.

  18. Mixed infection and clonal representativeness of a single sputum sample in tuberculosis patients from a penitentiary hospital in Georgia

    Directory of Open Access Journals (Sweden)

    Portaels Françoise

    2006-07-01

    Full Text Available Abstract Background Studies on recurrent tuberculosis (TB, TB molecular epidemiology and drug susceptibility testing rely on the analysis of one Mycobacterium tuberculosis isolate from a single sputum sample collected at different disease episodes. This scheme rests on the postulate that a culture of one sputum sample is homogeneous and representative of the total bacillary population in a patient. Methods We systematically analysed several pre-treatment isolates from each of 199 smear-positive male adult inmates admitted to a prison TB hospital by standard IS6110 DNA fingerprinting, followed by PCR typing based on multiple loci containing variable number of tandem repeats (VNTRs on a subset of isolates. Drug susceptibility testing (DST was performed on all isolates for isoniazid, rifampicin, streptomycin and ethambutol. Results We found mixed infection in 26 (13.1% cases. In contrast, analysis of a single pre-treatment isolate per patient would have led to missed mixed infections in all or 14 of these 26 cases by using only standard DNA fingerprinting or the PCR multilocus-based method, respectively. Differences in DST among isolates from the same patient were observed in 10 cases, of which 6 were from patients with mixed infection. Conclusion These results suggest that the actual heterogeneity of the bacillary population in patients, especially in high TB incidence settings, may be frequently underestimated using current analytical schemes. These findings have therefore important implications for correct interpretation and evaluation of molecular epidemiology data and in treatment evaluations.

  19. The effect of stimulus height on visual discrimination in horses

    OpenAIRE

    Hall, CA; Cassaday, HJ; Derrington, AM

    2003-01-01

    This study investigated the effect of stimulus height on the ability of horses to learn a simple visual discrimination task. Eight horses were trained to perform a two-choice black/white discrimination with stimuli presented at one of two heights: at ground level or at a height of 70cm from the ground. The height at which the stimuli were presented was alternated from one session to the next. All trials within a single session were presented at the same height. The criterion for learning was ...

  20. Isomorphism Between Estes’ Stimulus Fluctuation Model and a Physical- Chemical System

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    Makoto Yamaguchi

    2013-10-01

    Full Text Available Although Estes’ Stimulus Sampling Theory has almost completely lost its influence, its theoretical framework has not been disproved. Particularly, one theory in that framework, Stimulus Fluctuation Model, is still important because it explains spontaneous recovery. In this short note, the process of the theory is shown to be isomorphic to the diffusion of solution between compartments. Envisioning the theory as diffusion will make it appear less artificial and suggest natural extensions.

  1. EEG Differentiation Analysis and Stimulus Set Meaningfulness

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    Armand Mensen

    2017-10-01

    Full Text Available A set of images can be considered as meaningfully different for an observer if they can be distinguished phenomenally from one another. Each phenomenal difference must be supported by some neurophysiological differences. Differentiation analysis aims to quantify neurophysiological differentiation evoked by a given set of stimuli to assess its meaningfulness to the individual observer. As a proof of concept using high-density EEG, we show increased neurophysiological differentiation for a set of natural, meaningfully different images in contrast to another set of artificially generated, meaninglessly different images in nine participants. Stimulus-evoked neurophysiological differentiation (over 257 channels, 800 ms was systematically greater for meaningful vs. meaningless stimulus categories both at the group level and for individual subjects. Spatial breakdown showed a central-posterior peak of differentiation, consistent with the visual nature of the stimulus sets. Temporal breakdown revealed an early peak of differentiation around 110 ms, prominent in the central-posterior region; and a later, longer-lasting peak at 300–500 ms that was spatially more distributed. The early peak of differentiation was not accompanied by changes in mean ERP amplitude, whereas the later peak was associated with a higher amplitude ERP for meaningful images. An ERP component similar to visual-awareness-negativity occurred during the nadir of differentiation across all image types. Control stimulus sets and further analysis indicate that changes in neurophysiological differentiation between meaningful and meaningless stimulus sets could not be accounted for by spatial properties of the stimuli or by stimulus novelty and predictability.

  2. Development of a novel method for simultaneous concentration of viruses and protozoa from a single water sample.

    Science.gov (United States)

    Haramoto, Eiji; Katayama, Hiroyuki; Asami, Mari; Akiba, Michihiro

    2012-06-01

    A novel method, electronegative membrane-vortex (EMV) method, was developed for simultaneous concentration of viruses and protozoa from a single water sample. Viruses and protozoa in a water sample were mixed with a cation solution and adsorbed on an electronegative membrane. Concentrated virus and protozoa samples were obtained as supernatant and pellet fractions, respectively, by vigorous vortex mixing of the membrane and centrifugation of the eluted material. The highest recovery efficiencies of model microbes from river water and tap water by this EMV method were obtained using a mixed cellulose ester membrane with a pore size of 0.45 μm (Millipore) as the electronegative membrane and MgCl(2) as the cation solution. The recovery was 27.7-86.5% for poliovirus, 25.7-68.3% for coliphage Qβ, 28.0-60.0% for Cryptosporidium oocysts, and 35.0-53.0% for Giardia cysts. The EMV method detected successfully indigenous viruses and protozoa in wastewater and river water samples from the Kofu basin, Japan, showing an overall positive rate of 100% (43/43) for human adenovirus, 79% (34/43) for norovirus GI, 65% (28/43) for norovirus GII, 23% (10/43) for Cryptosporidium oocysts, and 60% (26/43) for Giardia cysts. By direct DNA sequencing, a total of four genotypes (AI, AII, B, and G) of Giardia intestinalis were identified in the water samples, indicating that the river water was contaminated with feces from various mammals, including humans. Copyright © 2012 Elsevier B.V. All rights reserved.

  3. Optimization of plasma sampling depth and aerosol gas flow rates for single particle inductively coupled plasma mass spectrometry analysis.

    Science.gov (United States)

    Kálomista, Ildikó; Kéri, Albert; Galbács, Gábor

    2017-09-01

    We performed experiments to assess the separate and also the combined effect of the sampling depth and the aerosol gas flow rates on the signal formation in single particle inductively coupled plasma mass spectrometry (spICP-MS) measurements by using dispersions containing Ag and Au NPs. It was found that the NP signal can significantly be improved by the optimization of the sampling depth. With respect to the "robust" setting, a signal improvement of nearly 100% could be achieved, which translates into a 25-30% improvement in size detection limits. It was also found that the shape of the spICP-MS signal histograms also change with the change of the plasma sampling depth. It was demonstrated that nanoparticle peak separation can also be significantly enhanced by using sampling depth optimization. The effect of the aerosol dilution gas flow, now standard in most ICP-MS instruments, on the spICP-MS signal formation was also studied for the first time in the literature, as this flow was hoped to make spICP-MS measurements more practical and faster via the on-line dilution of the aerosol generated from nano-dispersions. Our experimental results revealed that the dilution gas flow can only be used for a moderate aerosol dilution in spICP-MS measurements, if the gas flow going to the pneumatic nebulizer is proportionally lowered at the same time. This however was found to cause a significant worsening in the operation of the sample introduction system, which gives rise to a strong NP signal loss. Thus it was concluded that the use of the aerosol dilution gas flow, in its present form, can not be suggested for spICP-MS analysis. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. A Simple Fractionated Extraction Method for the Comprehensive Analysis of Metabolites, Lipids, and Proteins from a Single Sample.

    Science.gov (United States)

    Salem, Mohamed; Bernach, Michal; Bajdzienko, Krzysztof; Giavalisco, Patrick

    2017-06-01

    Understanding of complex biological systems requires the measurement, analysis and integration of multiple compound classes of the living cell, usually determined by transcriptomic, proteomic, metabolomics and lipidomic measurements. In this protocol, we introduce a simple method for the reproducible extraction of metabolites, lipids and proteins from biological tissues using a single aliquot per sample. The extraction method is based on a methyl tert-butyl ether: methanol: water system for liquid: liquid partitioning of hydrophobic and polar metabolites into two immiscible phases along with the precipitation of proteins and other macromolecules as a solid pellet. This method, therefore, provides three different fractions of specific molecular composition, which are fully compatible with common high throughput 'omics' technologies such as liquid chromatography (LC) or gas chromatography (GC) coupled to mass spectrometers. Even though the method was initially developed for the analysis of different plant tissue samples, it has proved to be fully compatible for the extraction and analysis of biological samples from systems as diverse as algae, insects, and mammalian tissues and cell cultures.

  5. Integrative analysis of single nucleotide polymorphisms and gene expression efficiently distinguishes samples from closely related ethnic populations

    Directory of Open Access Journals (Sweden)

    Yang Hsin-Chou

    2012-07-01

    Full Text Available Abstract Background Ancestry informative markers (AIMs are a type of genetic marker that is informative for tracing the ancestral ethnicity of individuals. Application of AIMs has gained substantial attention in population genetics, forensic sciences, and medical genetics. Single nucleotide polymorphisms (SNPs, the materials of AIMs, are useful for classifying individuals from distinct continental origins but cannot discriminate individuals with subtle genetic differences from closely related ancestral lineages. Proof-of-principle studies have shown that gene expression (GE also is a heritable human variation that exhibits differential intensity distributions among ethnic groups. GE supplies ethnic information supplemental to SNPs; this motivated us to integrate SNP and GE markers to construct AIM panels with a reduced number of required markers and provide high accuracy in ancestry inference. Few studies in the literature have considered GE in this aspect, and none have integrated SNP and GE markers to aid classification of samples from closely related ethnic populations. Results We integrated a forward variable selection procedure into flexible discriminant analysis to identify key SNP and/or GE markers with the highest cross-validation prediction accuracy. By analyzing genome-wide SNP and/or GE markers in 210 independent samples from four ethnic groups in the HapMap II Project, we found that average testing accuracies for a majority of classification analyses were quite high, except for SNP-only analyses that were performed to discern study samples containing individuals from two close Asian populations. The average testing accuracies ranged from 0.53 to 0.79 for SNP-only analyses and increased to around 0.90 when GE markers were integrated together with SNP markers for the classification of samples from closely related Asian populations. Compared to GE-only analyses, integrative analyses of SNP and GE markers showed comparable testing

  6. Stimulus-set location does not affect orthogonal stimulus-response compatibility.

    Science.gov (United States)

    Cho, Yang Seok; Proctor, Robert W

    2004-12-01

    In two-choice tasks for which stimuli and responses vary along orthogonal dimensions, one stimulus-response mapping typically yields better performance than another. For unimanual movement responses, the hand used to respond, hand posture (prone or supine), and response eccentricity influence this orthogonal stimulus-response compatibility (SRC) effect. All accounts of these phenomena attribute them to response-related processes. Two experiments examined whether manipulation of stimulus-set position along the dimension on which the stimuli varied influences orthogonal SRC in a manner similar to the way that response location does. The experiments differed in whether the stimulus dimension was vertical and the response dimension horizontal, or vice versa. In both experiments, an advantage of mapping up with right and down with left was evident for several response modes, and stimulus-set position had no influence on the orthogonal SRC effect. The lack of effect of stimulus-set position is in agreement with the emphasis that present accounts place on response-related processes. We favor a multiple asymmetric codes account, for which the present findings imply that the polarity of stimulus codes does not vary across task contexts although the polarity of response codes does.

  7. Classifying the Progression of Ductal Carcinoma from Single-Cell Sampled Data via Integer Linear Programming: A Case Study.

    Science.gov (United States)

    Catanzaro, Daniele; Shackney, Stanley E; Schaffer, Alejandro A; Schwartz, Russell

    2016-01-01

    Ductal Carcinoma In Situ (DCIS) is a precursor lesion of Invasive Ductal Carcinoma (IDC) of the breast. Investigating its temporal progression could provide fundamental new insights for the development of better diagnostic tools to predict which cases of DCIS will progress to IDC. We investigate the problem of reconstructing a plausible progression from single-cell sampled data of an individual with synchronous DCIS and IDC. Specifically, by using a number of assumptions derived from the observation of cellular atypia occurring in IDC, we design a possible predictive model using integer linear programming (ILP). Computational experiments carried out on a preexisting data set of 13 patients with simultaneous DCIS and IDC show that the corresponding predicted progression models are classifiable into categories having specific evolutionary characteristics. The approach provides new insights into mechanisms of clonal progression in breast cancers and helps illustrate the power of the ILP approach for similar problems in reconstructing tumor evolution scenarios under complex sets of constraints.

  8. Getting More from a Fiscal Stimulus

    OpenAIRE

    Theo Thomas

    2009-01-01

    The severity and global nature of the current financial and economic crisis has increased the role expected of fiscal policy in stimulating national and global demand, protecting vulnerable groups, and investing for future growth (International Monetary Fund, or IMF 2009). For those that can afford it, this means quickly designing and implementing fiscal stimulus packages. These new challe...

  9. Stimulus Configuration, Classical Conditioning, and Hippocampal Function.

    Science.gov (United States)

    Schmajuk, Nestor A.; DiCarlo, James J.

    1991-01-01

    The participation of the hippocampus in classical conditioning is described in terms of a multilayer network portraying stimulus configuration. A model of hippocampal function is presented, and computer simulations are used to study neural activity in the various brain areas mapped according to the model. (SLD)

  10. Verbal Stimulus Control and the Intraverbal Relation

    Science.gov (United States)

    Sundberg, Mark L.

    2016-01-01

    The importance of the intraverbal relation is missed in most theories of language. Skinner (1957) attributes this to traditional semantic theories of meaning that focus on the nonverbal referents of words and neglect verbal stimuli as separate sources of control for linguistic behavior. An analysis of verbal stimulus control is presented, along…

  11. Bigrams and the Richness of the Stimulus

    Science.gov (United States)

    Kam, Xuan-Nga Cao; Stoyneshka, Iglika; Tornyova, Lidiya; Fodor, Janet D.; Sakas, William G.

    2008-01-01

    Recent challenges to Chomsky's "poverty of the stimulus" thesis for language acquisition suggest that children's primary data may carry "indirect evidence" about linguistic constructions despite containing no instances of them. Indirect evidence is claimed to suffice for grammar acquisition, without need for innate knowledge. This article reports…

  12. Algorithm and program for precise determination of unit-cell parameters of single crystal taking into account the sample eccentricity

    Science.gov (United States)

    Dudka, A. P.; Smirnova, E. S.; Verin, I. A.; Bolotina, N. B.

    2017-07-01

    A technique has been developed to refine the unit-cell parameters of single crystals with minimization of the influence of instrumental errors on the result. The corresponding computational procedure HuberUB is added to the software package of Huber-5042 diffractometer with a point detector and closedcycle helium cryostat Displex DE-202. The parameters of unit cell, its orientation, the goniometer zero angles, the sample eccentricity, the distances in the goniometer, and the radiation wavelength were refined by the nonlinear least-squares method, which allows imposition of constraints on the unit-cell parameters, depending on the crystal symmetry. The technique is approved on a LuB12 single crystal. The unit-cell parameters are determined in a temperature range of 20-295 K, with an absolute error not larger than 0.0004 Å (the relative error is of 5 × 10-5). The estimates of the unit-cell parameters obtained by the proposed method are evidenced to be unbiased. Some specific features of the behavior of parameters in the ranges of 120-140 and 20-50 K are revealed, which correlate with the anomalies of the physical properties of the crystal.

  13. Stimulus conflation and tuning selectivity in V4 neurons: a model of visual crowding.

    Science.gov (United States)

    Motter, Brad C

    2018-01-01

    Visual crowding is a fundamental constraint on our ability to identify peripheral objects in cluttered environments. This study proposes a descriptive model for understanding crowding based on the tuning selectivity for stimuli within the receptive field (RF) and examines potential neural correlates in cortical area V4. For V4 neurons, optimally sized, letter-like stimuli are much smaller than the RF. This permits stimulus conflation, the fusing of separate objects into a single identity, to occur within the RF of single neurons. Flanking interactions between such stimuli were found to be limited to the RF. The response to an optimal stimulus centered in the neuron's RF, is suppressed by the simultaneous presentation of flanking stimuli within the RF. The degree of suppression is a function of the neuron's stimulus tuning properties and the position of the flanker within the RF. A single neuron may show suppression or facilitation depending on the detailed stimulus conditions and the relationship to tuning selectivity. Loss of activity in the set of neurons tuned to a particular stimulus alters its overall representation and potential identification, thus forming a basis for visual crowding effects. The mechanisms that determine the outcome of conflation are associated with object identification, and are not some other independent visual phenomena.

  14. pH(stat) vs. single extraction tests to evaluate heavy metals and arsenic leachability in environmental samples.

    Science.gov (United States)

    Rigol, A; Mateu, J; González-Núñez, R; Rauret, G; Vidal, M

    2009-01-19

    Here we compared the pH(stat) test, which examines the leachability of major elements (Ca, Mg, Al, Fe, and Mn), dissolved organic carbon, and trace elements (Cd, Zn, Cu, Pb, and As) in a wide pH range, with single extraction tests based on the use of mild extractants (calcium chloride, acetic acid or EDTA). For this purpose, we examined samples from a variety of environmental conditions (sludges, mineral soils, organic soils, and soils with particulate and/or soluble contamination). Extraction yields obtained with CaCl(2) (0.01 mol L(-1)) and CH(3)COOH (0.43 mol L(-1)) correlated well with those from the pH(stat) at the same pH (r=0.98 and 0.95, respectively), while the use of EDTA (0.05 mol L(-1)) led to systematically higher extraction yields than those quantified with the pH(stat) at the same pH. However, the pH(stat) test had three distinct advantages: (1) it revealed the relationship between the solubility of the main soil phases and pH; (2) it showed the variation in pollutant leachability due to changes in pH; and (3) it better predicted the maximum contaminant availability. Thus we propose that the pH(stat) is the best laboratory tests to evaluate the contaminant leachability over a wide range of sample types (soil, sludge, and sediment).

  15. Spiking neural circuits with dendritic stimulus processors : encoding, decoding, and identification in reproducing kernel Hilbert spaces.

    Science.gov (United States)

    Lazar, Aurel A; Slutskiy, Yevgeniy B

    2015-02-01

    We present a multi-input multi-output neural circuit architecture for nonlinear processing and encoding of stimuli in the spike domain. In this architecture a bank of dendritic stimulus processors implements nonlinear transformations of multiple temporal or spatio-temporal signals such as spike trains or auditory and visual stimuli in the analog domain. Dendritic stimulus processors may act on both individual stimuli and on groups of stimuli, thereby executing complex computations that arise as a result of interactions between concurrently received signals. The results of the analog-domain computations are then encoded into a multi-dimensional spike train by a population of spiking neurons modeled as nonlinear dynamical systems. We investigate general conditions under which such circuits faithfully represent stimuli and demonstrate algorithms for (i) stimulus recovery, or decoding, and (ii) identification of dendritic stimulus processors from the observed spikes. Taken together, our results demonstrate a fundamental duality between the identification of the dendritic stimulus processor of a single neuron and the decoding of stimuli encoded by a population of neurons with a bank of dendritic stimulus processors. This duality result enabled us to derive lower bounds on the number of experiments to be performed and the total number of spikes that need to be recorded for identifying a neural circuit.

  16. Single Particle-Inductively Coupled Plasma Mass Spectroscopy Analysis of Metallic Nanoparticles in Environmental Samples with Large Dissolved Analyte Fractions.

    Science.gov (United States)

    Schwertfeger, D M; Velicogna, Jessica R; Jesmer, Alexander H; Scroggins, Richard P; Princz, Juliska I

    2016-10-18

    There is an increasing interest to use single particle-inductively coupled plasma mass spectroscopy (SP-ICPMS) to help quantify exposure to engineered nanoparticles, and their transformation products, released into the environment. Hindering the use of this analytical technique for environmental samples is the presence of high levels of dissolved analyte which impedes resolution of the particle signal from the dissolved. While sample dilution is often necessary to achieve the low analyte concentrations necessary for SP-ICPMS analysis, and to reduce the occurrence of matrix effects on the analyte signal, it is used here to also reduce the dissolved signal relative to the particulate, while maintaining a matrix chemistry that promotes particle stability. We propose a simple, systematic dilution series approach where by the first dilution is used to quantify the dissolved analyte, the second is used to optimize the particle signal, and the third is used as an analytical quality control. Using simple suspensions of well characterized Au and Ag nanoparticles spiked with the dissolved analyte form, as well as suspensions of complex environmental media (i.e., extracts from soils previously contaminated with engineered silver nanoparticles), we show how this dilution series technique improves resolution of the particle signal which in turn improves the accuracy of particle counts, quantification of particulate mass and determination of particle size. The technique proposed here is meant to offer a systematic and reproducible approach to the SP-ICPMS analysis of environmental samples and improve the quality and consistency of data generated from this relatively new analytical tool.

  17. Pharmacokinetics of tulathromycin in plasma and milk samples after a single subcutaneous injection in lactating goats (Capra hircus).

    Science.gov (United States)

    Grismer, B; Rowe, J D; Carlson, J; Wetzlich, S E; Tell, L A

    2014-04-01

    Eight adult female dairy goats received one subcutaneous administration of tulathromycin at a dosage of 2.5 mg/kg body weight. Blood and milk samples were assayed for tulathromycin and the common fragment of tulathromycin, respectively, using liquid chromatography/mass spectrometry. Pharmacokinetic disposition of tulathromycin was analyzed by a noncompartmental approach. Mean plasma pharmacokinetic parameters (±SD) following single-dose administration of tulathromycin were as follows: C(max) (121.54 ± 19.01 ng/mL); T(max) (12 ± 12-24 h); area under the curve AUC(0→∞) (8324.54 ± 1706.56 ng·h/mL); terminal-phase rate constant λz (0.01 ± 0.002 h⁻¹); and terminal-phase rate constant half-life t1/2λz (67.20 h; harmonic). Mean milk pharmacokinetic parameters (±SD) following 45 days of sampling were as follows: Cmax (1594 ± 379.23 ng/mL); Tmax (12 ± 12-36 h); AUC(0→∞) (72,250.51 ± 18,909.57 ng·h/mL); λz (0.005 ± 0.001 h⁻¹); and t(1/2λz) (155.28 h; harmonic). All goats had injection-site reactions that diminished in size over time. The conclusions from this study were that tulathromycin residues are detectable in milk samples from adult goats for at least 45 days following subcutaneous administration, this therapeutic option should be reserved for cases where other treatment options have failed, and goat milk should be withheld from the human food chain for at least 45 days following tulathromycin administration. © 2013 John Wiley & Sons Ltd.

  18. Quantification and size characterisation of silver nanoparticles in environmental aqueous samples and consumer products by single particle-ICPMS.

    Science.gov (United States)

    Aznar, Ramón; Barahona, Francisco; Geiss, Otmar; Ponti, Jessica; José Luis, Tadeo; Barrero-Moreno, Josefa

    2017-12-01

    Single particle-inductively coupled plasma mass spectrometry (SP-ICPMS) is a promising technique able to generate the number based-particle size distribution (PSD) of nanoparticles (NPs) in aqueous suspensions. However, SP-ICPMS analysis is not consolidated as routine-technique yet and is not typically applied to real test samples with unknown composition. This work presents a methodology to detect, quantify and characterise the number-based PSD of Ag-NPs in different environmental aqueous samples (drinking and lake waters), aqueous samples derived from migration tests and consumer products using SP-ICPMS. The procedure is built from a pragmatic view and involves the analysis of serial dilutions of the original sample until no variation in the measured size values is observed while keeping particle counts proportional to the dilution applied. After evaluation of the analytical figures of merit, the SP-ICPMS method exhibited excellent linearity (r 2 >0.999) in the range (1-25) × 10 4 particlesmL -1 for 30, 50 and 80nm nominal size Ag-NPs standards. The precision in terms of repeatability was studied according to the RSDs of the measured size and particle number concentration values and a t-test (p = 95%) at the two intermediate concentration levels was applied to determine the bias of SP-ICPMS size values compared to reference values. The method showed good repeatability and an overall acceptable bias in the studied concentration range. The experimental minimum detectable size for Ag-NPs ranged between 12 and 15nm. Additionally, results derived from direct SP-ICPMS analysis were compared to the results conducted for fractions collected by asymmetric flow-field flow fractionation and supernatant fractions after centrifugal filtration. The method has been successfully applied to determine the presence of Ag-NPs in: lake water; tap water; tap water filtered by a filter jar; seven different liquid silver-based consumer products; and migration solutions (pure water and

  19. Spatio-temporal brain dynamics in a combined stimulus-stimulus and stimulus-response conflict task.

    Science.gov (United States)

    Frühholz, Sascha; Godde, Ben; Finke, Mareike; Herrmann, Manfred

    2011-01-01

    It is yet not well known whether different types of conflicts share common or rely on distinct brain mechanisms of conflict processing. We used a combined Flanker (stimulus-stimulus; S-S) and Simon (stimulus-response; S-R) conflict paradigm both in an fMRI and an EEG study. S-S conflicts induced stronger behavioral interference effects compared to S-R conflicts and the latter decayed with increasing response latencies. Besides some similar medial frontal activity across all conflict trials, which was, however, not statically consistent across trials, we especially found distinct activations depending on the type of conflict. S-S conflicts activated the anterior cingulate cortex and modulated the N2 and early P3 component with underlying source activity in inferior frontal cortex. S-R conflicts produced distinct activations in the posterior cingulate cortex and modulated the late P3b component with underlying source activity in superior parietal cortex. Double conflict trials containing both S-S and S-R conflicts revealed, first, distinct anterior frontal activity representing a meta-processing unit and, second, a sequential modulation of the N2 and the P3b component. The N2 modulation during double conflict trials was accompanied by increased source activity in the medial frontal gyrus (MeFG). In summary, S-S and S-R conflict processing mostly rely on distinct mechanisms of conflict processing and these conflicts differentially modulate the temporal stages of stimulus processing. Copyright © 2010 Elsevier Inc. All rights reserved.

  20. Genotyping of human parvovirus B19 in clinical samples from Brazil and Paraguay using heteroduplex mobility assay, single-stranded conformation polymorphism and nucleotide sequencing

    Directory of Open Access Journals (Sweden)

    Marcos César Lima de Mendonça

    2011-06-01

    Full Text Available Heteroduplex mobility assay, single-stranded conformation polymorphism and nucleotide sequencing were utilised to genotype human parvovirus B19 samples from Brazil and Paraguay. Ninety-seven serum samples were collected from individuals presenting with abortion or erythema infectiosum, arthropathies, severe anaemia and transient aplastic crisis; two additional skin samples were collected by biopsy. After the procedure, all clinical samples were classified as genotype 1.

  1. A safety assessment of rotary mode core sampling in flammable gas single shell tanks: Hanford Site, Richland, Washington

    Energy Technology Data Exchange (ETDEWEB)

    Raymond, R.E.

    1996-04-15

    This safety assessment (SA) addresses each of the required elements associated with the installation, operation, and removal of a rotary-mode core sampling (RMCS) device in flammable-gas single-shell tanks (SSTs). The RMCS operations are needed in order to retrieve waste samples from SSTs with hard layers of waste for which push-mode sampling is not adequate for sampling. In this SA, potential hazards associated with the proposed action were identified and evaluated systematically. Several potential accident cases that could result in radiological or toxicological gas releases were identified and analyzed and their consequences assessed. Administrative controls, procedures and design changes required to eliminate or reduce the potential of hazards were identified. The accidents were analyzed under nine categories, four of which were burn scenarios. In SSTS, burn accidents result in unacceptable consequences because of a potential dome collapse. The accidents in which an aboveground burn propagates into the dome space were shown to be in the ``beyond extremely unlikely`` frequency category. Given the unknown nature of the gas-release behavior in the SSTS, a number of design changes and administrative controls were implemented to achieve these low frequencies. Likewise, drill string fires and dome space fires were shown to be very low frequency accidents by taking credit for the design changes, controls, and available experimental and analytical data. However, a number of Bureau of Mines (BOM) tests must be completed before some of the burn accidents can be dismissed with high confidence. Under the category of waste fires, the possibility of igniting the entrapped gases and the waste itself were analyzed. Experiments are being conducted at the BOM to demonstrate that the drill bit is not capable of igniting the trapped gas in the waste. Laboratory testing and thermal analysis demonstrated that, under normal operating conditions, the drill bit will not create high

  2. A safety assessment of rotary mode core sampling in flammable gas single shell tanks: Hanford Site, Richland, Washington

    International Nuclear Information System (INIS)

    Raymond, R.E.

    1996-01-01

    This safety assessment (SA) addresses each of the required elements associated with the installation, operation, and removal of a rotary-mode core sampling (RMCS) device in flammable-gas single-shell tanks (SSTs). The RMCS operations are needed in order to retrieve waste samples from SSTs with hard layers of waste for which push-mode sampling is not adequate for sampling. In this SA, potential hazards associated with the proposed action were identified and evaluated systematically. Several potential accident cases that could result in radiological or toxicological gas releases were identified and analyzed and their consequences assessed. Administrative controls, procedures and design changes required to eliminate or reduce the potential of hazards were identified. The accidents were analyzed under nine categories, four of which were burn scenarios. In SSTS, burn accidents result in unacceptable consequences because of a potential dome collapse. The accidents in which an aboveground burn propagates into the dome space were shown to be in the ''beyond extremely unlikely'' frequency category. Given the unknown nature of the gas-release behavior in the SSTS, a number of design changes and administrative controls were implemented to achieve these low frequencies. Likewise, drill string fires and dome space fires were shown to be very low frequency accidents by taking credit for the design changes, controls, and available experimental and analytical data. However, a number of Bureau of Mines (BOM) tests must be completed before some of the burn accidents can be dismissed with high confidence. Under the category of waste fires, the possibility of igniting the entrapped gases and the waste itself were analyzed. Experiments are being conducted at the BOM to demonstrate that the drill bit is not capable of igniting the trapped gas in the waste. Laboratory testing and thermal analysis demonstrated that, under normal operating conditions, the drill bit will not create high

  3. Discrimination learning with variable stimulus 'salience'

    Directory of Open Access Journals (Sweden)

    Treviño Mario

    2011-08-01

    Full Text Available Abstract Background In nature, sensory stimuli are organized in heterogeneous combinations. Salient items from these combinations 'stand-out' from their surroundings and determine what and how we learn. Yet, the relationship between varying stimulus salience and discrimination learning remains unclear. Presentation of the hypothesis A rigorous formulation of the problem of discrimination learning should account for varying salience effects. We hypothesize that structural variations in the environment where the conditioned stimulus (CS is embedded will be a significant determinant of learning rate and retention level. Testing the hypothesis Using numerical simulations, we show how a modified version of the Rescorla-Wagner model, an influential theory of associative learning, predicts relevant interactions between varying salience and discrimination learning. Implications of the hypothesis If supported by empirical data, our model will help to interpret critical experiments addressing the relations between attention, discrimination and learning.

  4. STIMULUS GENERALIZATION OF THE EFFECTS OF PUNISHMENT.

    Science.gov (United States)

    HONIG, W K; SLIVKA, R M

    1964-01-01

    Three pigeons were trained to respond to seven spectral stimulus values ranging from 490 to 610 mmu and displayed in random order on a response key. After response rates had equalized to these values, a brief electric shock was administered when the subject (S) responded to the central value (550 mmu) while positive reinforcement for all values was maintained. Initially, there was broad generalization of the resulting depression in response rate, but the gradients grew steeper in the course of testing. When punishment was discontinued, the rates to all values recovered, and equal responding to all stimuli was reattained by two of the Ss. Stimulus control over the effects of punishment was clearly demonstrated in the form of a generalization gradient; this probably resulted from the combined effects of generalization of the depression associated with punishment and discrimination between the punished value and neutral stimuli.

  5. Sensitivity of bimodal listeners to interaural time differences with modulated single- and multiple-channel stimuli.

    Science.gov (United States)

    Francart, Tom; Lenssen, Anneke; Wouters, Jan

    2011-01-01

    In a previous study, it was shown that users of a cochlear implant and a contralateral hearing aid are sensitive to interaural time differences (ITDs). In the current study, we investigated (1) the influence on ITD sensitivity of bilaterally varying the place of excitation in the cochlea and of modulation frequency, and (2) the sensitivity to ITD with a 3-channel stimulus generated using continuous-interleaved-sampling (CIS)-like processing. The stimuli were (1) a high-frequency carrier (acoustic sinusoid and single-electrode electric pulse train), modulated with a half-wave-rectified low-frequency sinusoid (a so-called transposed stimulus), and (2) a 3-channel stimulus, generated by sending an acoustic click train through processing similar to the CIS strategy. Four bimodal listeners were sensitive to ITD for both stimulus types. For the first stimulus type, there was no significant influence on ITD sensitivity of the acoustic carrier frequency. Performance decreased with increasing modulation frequency with a limit of sensitivity at around 150-200 Hz. Sensitivity was similar for the single- and 3-channel stimulus. The results indicate the possibility of ITD perception with adapted clinical processors, which can lead to improved sound source localization and binaural unmasking. Copyright © 2010 S. Karger AG, Basel.

  6. Understanding smell--the olfactory stimulus problem.

    Science.gov (United States)

    Auffarth, Benjamin

    2013-09-01

    The main problem with sensory processing is the difficulty in relating sensory input to physiological responses and perception. This is especially problematic at higher levels of processing, where complex cues elicit highly specific responses. In olfaction, this relationship is particularly obfuscated by the difficulty of characterizing stimulus statistics and perception. The core questions in olfaction are hence the so-called stimulus problem, which refers to the understanding of the stimulus, and the structure-activity and structure-odor relationships, which refer to the molecular basis of smell. It is widely accepted that the recognition of odorants by receptors is governed by the detection of physico-chemical properties and that the physical space is highly complex. Not surprisingly, ideas differ about how odor stimuli should be classified and about the very nature of information that the brain extracts from odors. Even though there are many measures for smell, there is none that accurately describes all aspects of it. Here, we summarize recent developments in the understanding of olfaction. We argue that an approach to olfactory function where information processing is emphasized could contribute to a high degree to our understanding of smell as a perceptual phenomenon emerging from neural computations. Further, we argue that combined analysis of the stimulus, biology, physiology, and behavior and perception can provide new insights into olfactory function. We hope that the reader can use this review as a competent guide and overview of research activities in olfactory physiology, psychophysics, computation, and psychology. We propose avenues for research, particularly in the systematic characterization of receptive fields and of perception. Copyright © 2013 Elsevier Ltd. All rights reserved.

  7. Searching for stable Na-ordered phases in single-crystal samples of γ-NaxCoO2

    Science.gov (United States)

    Shu, G. J.; Prodi, Andrea; Chu, S. Y.; Lee, Y. S.; Sheu, H. S.; Chou, F. C.

    2007-11-01

    We report on the preparation and characterization of single-crystal γ phase NaxCoO2 with 0.25≤x≤0.84 using a nonaqueous electrochemical chronoamperemetry technique. By carefully mapping the overpotential versus x (for xfind six distinct stable phases with Na levels corresponding to xtilde 0.75, 0.71, 0.50, 0.43, 0.33, and 0.25. The composition with x≃0.55 appears to have a critical Na concentration which separates samples with different magnetic behavior as well as different Na ion diffusion mechanisms. Chemical analysis of an aged crystal reveals different Na ion diffusion mechanisms above and below xc˜0.53 , where the diffusion process above xc has a diffusion coefficient about five times larger than that below xc . The series of crystals were studied with x-ray diffraction, susceptibility, and transport measurements. The crystal with x=0.5 shows a weak ferromagnetic transition below T=27K in addition to the usual transitions at T=51 and 88K . The resistivity of the Curie-Weiss metallic Na0.71CoO2 composition has a very low residual resistivity, which attests to the high homogeneity of the crystals prepared by this improved electrochemical method. Our results on the various stable crystal compositions point to the importance of Na ion ordering across the phase diagram.

  8. A device for the application of uniaxial strain to single crystal samples for use in synchrotron radiation experiments

    Energy Technology Data Exchange (ETDEWEB)

    Gannon, L. [Clarendon Laboratory, University of Oxford Physics Department, Parks Road, Oxford OX1 3PU (United Kingdom); Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 ODE (United Kingdom); Bosak, A. [European Synchrotron Radiation Facility, BP 220, F-38043 Grenoble Cedex (France); Burkovsky, R. G. [European Synchrotron Radiation Facility, BP 220, F-38043 Grenoble Cedex (France); Peter the Great Saint-Petersburg Polytechnic University, 29 Politekhnicheskaya, 195251, St.-Petersburg (Russian Federation); Nisbet, G.; Hoesch, M., E-mail: Moritz.Hoesch@diamond.ac.uk [Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 ODE (United Kingdom); Petrović, A. P. [DPMC-MaNEP, Université de Genève, Quai Ernest-Ansermet 24, 1211 Genève 4 (Switzerland)

    2015-10-15

    We present the design, construction, and testing of a straining device compatible with many different synchrotron radiation techniques, in a wide range of experimental environments (including low temperature, high field and ultra-high vacuum). The device has been tested by X-ray diffraction on single crystal samples of quasi-one-dimensional Cs{sub 2}Mo{sub 6}Se{sub 6} and K{sub 2}Mo{sub 6}Se{sub 6}, in which microscopic strains up to a Δc/c = 0.12% ± 0.01% change in the c lattice parameters have been achieved. We have also used the device in an inelastic X-ray scattering experiment, to probe the strain-dependent speed of sound ν along the c axis. A reduction Δν/ν of up to −3.8% was obtained at a strain of Δc/c = 0.25% in K{sub 2}Mo{sub 6}Se{sub 6}.

  9. A disposable screen-printed silver strip sensor for single drop analysis of halide in biological samples.

    Science.gov (United States)

    Chiu, Mei-Hsin; Cheng, Wan-Ling; Muthuraman, Govindan; Hsu, Cheng-Teng; Chung, Hsieh-Hsun; Zen, Jyh-Myng

    2009-06-15

    A screen-printed silver strip with three-electrode configuration of Ag-working, Ag-counter and Ag/Ag(x)O reference electrodes was developed for simultaneous determination of chloride, bromide and iodide in aqueous solutions. It was fabricated simply by screen-printing silver ink onto a polypropylene (PP) base. The in-situ prepared Ag/Ag(x)O reference electrode can avoid the leaching interference in chloride detection while using a conventional Ag/AgCl reference electrode. A single drop of analyte (50 microl) is enough to determine iodide, bromide and chloride by measuring the well-separated oxidation peak currents of respective silver halides. The calibration graph was linear from 10 microM to 20 mM for iodide and bromide and 100 microM to 20 mM for chloride and the detection limit (S/N=3) was 3.05 microM, 2.95 microM and 18.83 microM for iodide, bromide and chloride, respectively. The strip is designed to be disposable and as such manual polishing is not necessary. The proposed sensor is not only simple to manufacture and easy to operate but also fast and precise with little detection volume. It is successfully applied to the determination of halide ions in real samples.

  10. Two Pathways to Stimulus Encoding in Category Learning?

    Science.gov (United States)

    Davis, Tyler; Love, Bradley C.; Maddox, W. Todd

    2008-01-01

    Category learning theorists tacitly assume that stimuli are encoded by a single pathway. Motivated by theories of object recognition, we evaluate a dual-pathway account of stimulus encoding. The part-based pathway establishes mappings between sensory input and symbols that encode discrete stimulus features, whereas the image-based pathway applies holistic templates to sensory input. Our experiments use rule-plus-exception structures in which one exception item in each category violates a salient regularity and must be distinguished from other items. In Experiment 1, we find that discrete representations are crucial for recognition of exceptions following brief training. Experiments 2 and 3 involve multi-session training regimens designed to encourage either part or image-based encoding. We find that both pathways are able to support exception encoding, but have unique characteristics. We speculate that one advantage of the part-based pathway is the ability to generalize across domains, whereas the image-based pathway provides faster and more effortless recognition. PMID:19460948

  11. Measuring word complexity in speech screening: single-word sampling to identify phonological delay/disorder in preschool children.

    Science.gov (United States)

    Anderson, Carolyn; Cohen, Wendy

    2012-01-01

    Children's speech sound development is assessed by comparing speech production with the typical development of speech sounds based on a child's age and developmental profile. One widely used method of sampling is to elicit a single-word sample along with connected speech. Words produced spontaneously rather than imitated may give a more accurate indication of a child's speech development. A published word complexity measure can be used to score later-developing speech sounds and more complex word patterns. There is a need for a screening word list that is quick to administer and reliably differentiates children with typically developing speech from children with patterns of delayed/disordered speech. To identify a short word list based on word complexity that could be spontaneously named by most typically developing children aged 3;00-5;05 years. One hundred and five children aged between 3;00 and 5;05 years from three local authority nursery schools took part in the study. Items from a published speech assessment were modified and extended to include a range of phonemic targets in different word positions in 78 monosyllabic and polysyllabic words. The 78 words were ranked both by phonemic/phonetic complexity as measured by word complexity and by ease of spontaneous production. The ten most complex words (hereafter Triage 10) were named spontaneously by more than 90% of the children. There was no significant difference between the complexity measures for five identified age groups when the data were examined in 6-month groups. A qualitative analysis revealed eight children with profiles of phonological delay or disorder. When these children were considered separately, there was a statistically significant difference (p speech from those with delayed or disordered speech patterns. The Triage 10 words can be used as a screening tool for triage and general assessment and have the potential to monitor progress during intervention. Further testing is being undertaken to

  12. A generic-tee-plenum mixing system for application to single point aerosol sampling in stacks and ducts.

    Science.gov (United States)

    Han, Taewon; O'Neal, Dennis L; Ortiz, Carlos A

    2007-01-01

    The ANSI/HPS-N13.1-1999 standard is based on the concept of obtaining a single point representative sample from a location where the velocity and contaminant profiles are relatively uniform. It is difficult to predict the level of mixing in an arbitrary stack or duct without experimental data to meet the ANSI/HPS N13.1-1999 requirements. The goal of this study was to develop experimental data for a range of conditions in "S" (S-shaped configuration) duct systems with different mixing elements and "S" systems having one or two mixing elements. Results were presented in terms of the coefficients of variation (COVs) for velocity, tracer gas, and 10-mum aerodynamic diameter (AD) aerosol particle profiles at different downstream locations for each mixing element. Five mixing elements were tested, including a 90 degrees elbow, a commercial static mixer, a Small-Horizontal Generic-Tee-Plenum (SH-GTP), a Small-Vertical Generic-Tee-Plenum (SV-GTP), and a Large-Horizontal Generic-Tee-Plenum (LH-GTP) system. The COVs for velocity, gas concentration, and aerosol particles for the three GTP systems were all determined to be less than 8%. Tests with two different sizes of GTPs were conducted, and the results showed the performance of the GTPs was relatively unaffected by either size or velocity as reflected by the Reynolds number. The pressure coefficients were 0.59, 0.57, and 0.65, respectively, for the SH-GTP, SV-GTP, and LH-GTP. The pressure drop for the GTPs was approximately twice that of the round elbow, but a factor of 5 less than a Type IV Air Blender. The GTP was developed to provide a sampling location less than 4-duct diameters downstream of a mixing element with low pressure drop condition. The object of the developmental effort was to provide a system that could be employed in new stack; however, the concept of GTPs could also be retrofitted onto existing system applications as well. Results from these tests show that the system performance is well within the ANSI

  13. Feasibility study of a single-shot 3D electron bunch shape monitor with an electro-optic sampling technique

    Directory of Open Access Journals (Sweden)

    Yuichi Okayasu

    2013-05-01

    Full Text Available We developed a three-dimensional electron bunch charge distribution (3D-BCD monitor with single-shot detection, and a spectral decoding based electro-optic (EO sampling technique for a nondestructive monitor enables real-time reconstruction of the three-dimensional distribution of a bunch charge. We realized three goals by simultaneously probing a number of Pockels EO crystals that surround the electron beam axis with hollow and radial polarized laser pulses. First, we performed a feasibility test as a simple case of a 3D-BCD monitor probing two ZnTe crystals as EO detectors installed on the opposite angle to the electron beam axis and confirmed that we simultaneously obtained both EO signals. Since the adopted hollow probe laser pulse is not only radially polarized but also temporally shifted azimuthally, some disorders in the radial polarization distribution of such a laser pulse were numerically analyzed with a plane-wave expansion method. Based on the above investigations, the 3D-BCD monitor is feasible both in experimental and numerical estimations. Furthermore, we previously developed a femtosecond response organic crystal as a Pockels EO detector and a broadband probe laser (≥350  nm in FWHM; the 3D-BCD monitor realizes 30- to 40-fs (FWHM temporal resolution. Eventually, the monitor is expected to be equipped in such advanced accelerators as XFEL to measure and adjust the electron bunch charge distribution in real time. The 3D-BCD measurement works as a critical tool to provide feedback to seeded FELs.

  14. On the preparation of as-produced and purified single-walled carbon nanotube samples for standardized X-ray diffraction characterization

    International Nuclear Information System (INIS)

    Allaf, Rula M.; Rivero, Iris V.; Spearman, Shayla S.; Hope-Weeks, Louisa J.

    2011-01-01

    The aim of this research was to specify proper sample conditioning for acquiring representative X-ray diffraction (XRD) profiles for single-walled carbon nanotube (SWCNT) samples. In doing so, a specimen preparation method for quantitative XRD characterization of as-produced and purified arc-discharge SWCNT samples has been identified. Series of powder XRD profiles were collected at different temperatures, states, and points of time to establish appropriate conditions for acquiring XRD profiles without inducing much change to the specimen. It was concluded that heating in the 300-450 deg. C range for 20 minutes, preferably vacuum-assisted, and then sealing the sample is an appropriate XRD specimen preparation technique for purified arc-discharge SWCNT samples, while raw samples do not require preconditioning for characterization. - Graphical Abstract: A sample preparation method for XRD characterization of as-produced and purified arc-discharge SWCNT samples is identified. The preparation technique seeks to acquire representative XRD profiles without inducing changes to the samples. Purified samples required 20 minutes of heating at (300-450)deg. C, while raw samples did not require preconditioning for characterization. Highlights: → Purification routines may induce adsorption onto the SWCNT samples. → Heating a SWCNT sample may result in material loss, desorption, and SWCNTs closing. → Raw arc-discharge samples do not require preparation for XRD characterization. → Heating is appropriate specimen preparation for purified and heat-treated samples. → XRD data fitting is required for structural analysis of SWCNT bundles.

  15. Determination of the technetium-99m mercaptoacetyltriglycine plasma clearance in children by means of a single blood sample: a multicentre study

    International Nuclear Information System (INIS)

    Piepsz, A.; Gordon, I.; Hahn, K.; Kolinska, J.; Kotzerke, J.; Sixt, R.

    1993-01-01

    A multicentree European study was undertaken in order to determine a reasonable algorithm allowing the determination of overall technetium-99m mercaptoacetyltriglycine clearance using a single blood sample. Employing multiple blood sample clearance as a reference method, it was shown that an acceptable estimation of the MAG3 renal clearance could be obtained using a blood sample taken at any time between 30 and 40 min after tracer injection. After correction for body surface area comparison of clearance determined using (a) the single blood sample and (b) the multiple blood samples provided a coefficient of correlation of 0.949 and an SEE of 27 ml/min. This algorithm is valid for clearance values higher than 100 ml/min/1.73 m 2 and for children older than 1 year of age. (orig.)

  16. Isomorphisms between psychological processes and neural mechanisms: from stimulus elements to genetic markers of activity.

    Science.gov (United States)

    Fanselow, Michael S; Zelikowsky, Moriel; Perusini, Jennifer; Barrera, Vanessa Rodriguez; Hersman, Sarah

    2014-02-01

    Traditional learning theory has developed models that can accurately predict and describe the course of learned behavior. These "psychological process" models rely on hypothetical constructs that are usually thought to be not directly measurable or manipulable. Recently, and mostly in parallel, the neural mechanisms underlying learning have been fairly well elucidated. The argument in this essay is that we can successfully uncover isomorphisms between process and mechanism and that this effort will help advance our theories about both processes and mechanisms. We start with a brief review of error-correction circuits as a successful example. Then we turn to the concept of stimulus elements, where the conditional stimulus is hypothesized to be constructed of a multitude of elements only some of which are sampled during any given experience. We discuss such elements with respect to how they explain acquisition of associative strength as an incremental process. Then we propose that for fear conditioning, stimulus elements and basolateral amygdala projection neurons are isomorphic and that the activational state of these "elements" can be monitored by the expression of the mRNA for activity-regulated cytoskeletal protein (ARC). Finally we apply these ideas to analyze recent data examining ARC expression during contextual fear conditioning and find that there are indeed many similarities between stimulus elements and amygdala neurons. The data also suggest some revisions in the conceptualization of how the population of stimulus elements is sampled from. Copyright © 2013 Elsevier Inc. All rights reserved.

  17. Persons with multiple disabilities engage in stimulus choice and postural control with the support of a technology-aided program.

    Science.gov (United States)

    Lancioni, Giulio E; Singh, Nirbhay N; O'Reilly, Mark F; Sigafoos, Jeff; Perilli, Viviana; Campodonico, Francesca; Marchiani, Paola; Lang, Russell

    2015-05-01

    Technology-aided programs have been reported to help persons with disabilities develop adaptive responding and control problem behavior/posture. This study assessed one such program in which choice of stimulus events was used as adaptive responding for three adults with multiple disabilities. A computer system presented the participants stimulus samples. For each sample, they could perform a choice response (gaining access to the related stimulus whose length they could extend) or abstain from responding (making the system proceed to the next sample). Once choice responding had strengthened, the program also targeted the participants' problem posture (i.e., head and trunk forward bending). The stimulus exposure gained with a choice response was interrupted if the problem posture occurred. All three participants successfully (a) managed choice responses and access to preferred stimuli and (b) gained postural control (i.e., reducing the problem posture to very low levels). The practical implications of those results are discussed. © The Author(s) 2015.

  18. Stimulus-Parity Synaesthesia versus Stimulus-Dichotomy Synaesthesia: Odd, Even or Something Else?

    Directory of Open Access Journals (Sweden)

    Rebekah C. White

    2015-02-01

    Full Text Available In stimulus-parity synaesthesia, a range of stimuli—for example, letters, numbers, weekdays, months, and colours (the inducers—elicit an automatic feeling of oddness or evenness (the concurrent. This phenomenon was first described by Théodore Flournoy in 1893, and has only recently been “rediscovered.” Here, we describe an individual who experiences a comparable phenomenon, but uses the labels negative and positive rather than odd and even. Stimulus-parity synaesthesia may be broader than first supposed, and it is important that assessments are sensitive to this breadth.

  19. Sample Preparation Methods Following CellSearch Approach Compatible of Single-Cell Whole-Genome Amplification: An Overview

    NARCIS (Netherlands)

    Swennenhuis, Joost Franciscus; Terstappen, Leonardus Wendelinus Mathias Marie; Kroneis, Thomas

    2015-01-01

    Single cells are increasingly used to determine the heterogeneity of therapy targets in the genome during the course of a disease. The first challenge using single cells is to isolate these cells from the surrounding cells, especially when the targeted cells are rare. A number of techniques have

  20. Quantification of a contact stimulus by diapers

    Science.gov (United States)

    Nomata, Takuya; Okuyama, Takeshi; Teraoka, Hiromi; Murakami, Yasuo; Miyazawa, Kiyoshi; Tanaka, Mami

    2010-01-01

    This paper describes a development of a sensor system for measurement of a contact stimulus which diapers give to infants. A polyvinyliden fluoride (PVDF) film and a strain gauge are used as the sensor receptors. The PVDF is a kind of piezoelectric material. The sensor consists of a surface contact layer, a PVDF film, a strain gauge and an aluminum plate. First, in order to investigate the sensor performance, the sensor was located on a silicone plate and the upper part of the sensor was rubbed with an acrylic artificial finger. The finger enabled the measurement to carry out at a constant speed and force. Next, the sensor was attached on an infant dummy and the sensor outputs were measured under conditions with and without diapers. By comparison of the output under two different conditions, it was confirmed that there is a clearly difference between the two conditions. It was found that the developed sensor system has the possibility to quantify a contact stimulus which diapers give infants.

  1. Hospital Clowning as Play Stimulus in Healthcare

    Directory of Open Access Journals (Sweden)

    Laura Anes

    2014-10-01

    Full Text Available A serious illness, a chronic medical condition or a hospital bed should not deny any child her/his basic right to play, a right essential for children’s development and general wellbeing. In fact, it is in these frightening and anxious moments that play and the stimulus that it provides can help the most. This article will focus on the impacts and benefits of professional hospital clowning for the wellbeing and recovery process of ill and hospitalized children. Our experience has shown that through interactive play and humor, “clowndoctors” can create an enabling and supportive environment that facilitates children’s adaptation to the hospital setting and improves their acceptance of medical procedures and staff. While moving from bedside to bedside, RED NOSES clowndoctors encourage children’s active participation and support their natural instinct to play, fully including them in the interaction, if the children wish to do so. Therefore, clowndoctor performances offer ill children much needed stimulus, self-confidence and courage, elements fundamental to reducing their vulnerability. In this piece, a special emphasis will be put on the various approaches used by RED NOSES clowndoctors to bond and reach out to children suffering from different medical conditions.

  2. Testing single-grain quartz OSL methods using sediment samples with independent age control from the Bordes-Fitte rockshelter (Roches d'Abilly site, Central France)

    DEFF Research Database (Denmark)

    Thomsen, Kristina Jørkov; Murray, Andrew Sean; Buylaert, Jan-Pieter

    2016-01-01

    We present quartz single-grain dose distributions for four well-bleached and unmixed sediment samples with independent age control (22–48 ka), from the archaeologically important Bordes-Fitte rockshelter at Roches d'Abilly, France. This site has previously been dated using 14C AMS dating and stan......We present quartz single-grain dose distributions for four well-bleached and unmixed sediment samples with independent age control (22–48 ka), from the archaeologically important Bordes-Fitte rockshelter at Roches d'Abilly, France. This site has previously been dated using 14C AMS dating...

  3. Effect of single-layer centrifugation or washing on frozen-thawed donkey semen quality: Do they have the same effect regardless of the quality of the sample?

    Science.gov (United States)

    Ortiz, I; Dorado, J; Morrell, J M; Crespo, F; Gosálvez, J; Gálvez, M J; Acha, D; Hidalgo, M

    2015-07-15

    The aims of this study were to determine the sperm quality of frozen-thawed donkey sperm samples after single-layer centrifugation (SLC) using Androcoll-E in comparison to sperm washing or no centrifugation and to determine if the effect on the sperm quality after SLC or sperm washing depends on the quality of the sample. Frozen-thawed sperm samples from Andalusian donkeys were divided into three aliquots, and they were processed using three different techniques after thawing: uncentrifuged diluted control (UDC), sperm washing (SW), and SLC. Afterward, sperm quality index was estimated by integrating all parameters (total and progressive sperm motility, membrane integrity, and DNA fragmentation) in a single value. The relationship between the sperm quality of thawed UDC samples and the effect on sperm parameters in SW and SLC-selected samples was assessed. Sperm quality index was significantly higher (P < 0.001) in SLC (0.8 ± 0.0) samples than that in UDC (0.6 ± 0.0) and SW (0.6 ± 0.0) samples, regardless of the sperm quality index after thawing of the sperm sample. In conclusion, SLC of frozen-thawed donkey spermatozoa using Androcoll-E-Small can be a suitable procedure for selecting frozen-thawed donkey sperm with better quality, in particular in those samples where an improvement in motility is needed. Copyright © 2015 Elsevier Inc. All rights reserved.

  4. Is the potential evoked by visual stimulus dependent on verbal instruction, which determined the stimulus significance?

    Czech Academy of Sciences Publication Activity Database

    Roman, R.; Brázdil, M.; Jurák, Pavel; Kukletal, M.; Rektor, I.

    2001-01-01

    Roč. 41, č. 5 (2001), s. 224 - 226 ISSN 0960-7560 R&D Projects: GA ČR GA102/02/1339 Institutional research plan: CEZ:AV0Z2065902 Keywords : visual stimulus * intracerebrally recorded EEG * epileptogenic zone Subject RIV: FA - Cardiovascular Diseases incl. Cardiotharic Surgery

  5. Preparation and Loading Process of Single Crystalline Samples into a Gas Environmental Cell Holder for In Situ Atomic Resolution Scanning Transmission Electron Microscopic Observation.

    Science.gov (United States)

    Straubinger, Rainer; Beyer, Andreas; Volz, Kerstin

    2016-06-01

    A reproducible way to transfer a single crystalline sample into a gas environmental cell holder for in situ transmission electron microscopic (TEM) analysis is shown in this study. As in situ holders have only single-tilt capability, it is necessary to prepare the sample precisely along a specific zone axis. This can be achieved by a very accurate focused ion beam lift-out preparation. We show a step-by-step procedure to prepare the sample and transfer it into the gas environmental cell. The sample material is a GaP/Ga(NAsP)/GaP multi-quantum well structure on Si. Scanning TEM observations prove that it is possible to achieve atomic resolution at very high temperatures in a nitrogen environment of 100,000 Pa.

  6. Decoding Subjective Intensity of Nociceptive Pain from Pre-stimulus and Post-stimulus Brain Activities

    Directory of Open Access Journals (Sweden)

    Yiheng eTu

    2016-04-01

    Full Text Available Pain is a highly subjective experience. Self-report is the gold standard for pain assessment in clinical practice, but it may not be available or reliable in some populations. Neuroimaging data, such as electroencephalography (EEG and functional magnetic resonance imaging (fMRI, have the potential to be used to provide physiology-based and quantitative nociceptive pain assessment tools that complements self-report. However, existing neuroimaging-based nociceptive pain assessments only rely on the information in pain-evoked brain activities, but neglect the fact that the perceived intensity of pain is also encoded by ongoing brain activities prior to painful stimulation. Here, we proposed to use machine learning algorithms to decode pain intensity from both pre-stimulus ongoing and post-stimulus evoked brain activities. Neural features that were correlated with intensity of laser-evoked nociceptive pain were extracted from high-dimensional pre- and post-stimulus EEG and fMRI activities using partial least-squares regression (PLSR. Further, we used support vector machine (SVM to predict the intensity of pain from pain-related time-frequency EEG patterns and BOLD-fMRI patterns. Results showed that combining predictive information in pre- and post-stimulus brain activities can achieve significantly better performance in classifying high-pain and low-pain and in predicting the rating of perceived pain than only using post-stimulus brain activities. Therefore, the proposed pain prediction method holds great potential in basic research and clinical applications.

  7. Transfers of stimulus function during roulette wagering.

    Science.gov (United States)

    Dixon, Mark R; Enoch, Mary Rachel; Belisle, Jordan

    2017-10-01

    Twenty-five recreational gamblers were initially asked to place bets on either red or black positions on a roulette board in a simulated casino setting. Each participant was then exposed to a stimulus pairing observing procedure which attempted to develop equivalence classes between one color (black or red) and traditionally positive words (e.g., love, happy, sex) and another color (black or red) and traditionally negative words (e.g., death, cancer, taxes), in the absence of consequence manipulations. Twenty-one of the twenty-five participants demonstrated greater response allocation to the color position on the roulette board that participated in a relational network with the positive words. Variations in sequencing of experimental conditions had no impact on poststimulus-pairing wagers, but did impact tests for equivalence accuracy. © 2017 Society for the Experimental Analysis of Behavior.

  8. Development of single step RT-PCR for detection of Kyasanur forest disease virus from clinical samples

    Directory of Open Access Journals (Sweden)

    Gouri Chaubal

    2018-02-01

    Discussion and conclusion: The previously published sensitive real time RT-PCR assay requires higher cost in terms of reagents and machine setup and technical expertise has been the primary reason for development of this assay. A single step RT-PCR is relatively easy to perform and more cost effective than real time RT-PCR in smaller setups in the absence of Biosafety Level-3 facility. This study reports the development and optimization of single step RT-PCR assay which is more sensitive and less time-consuming than nested RT-PCR and cost effective for rapid diagnosis of KFD viral RNA.

  9. Improved methodology for identification of protists and microalgae from plankton samples preserved in Lugol's iodine solution: combining microscopic analysis with single-cell PCR.

    Science.gov (United States)

    Auinger, Barbara M; Pfandl, Karin; Boenigk, Jens

    2008-04-01

    Here we introduce a method for quantitative analysis of planktonic protists and microalgae from preserved field samples combining morphological and small-subunit (SSU) rRNA gene sequence analysis. We linked a microscopic screening with PCR of single cells using field samples preserved with Lugol's iodine solution. Cells possessing a rigid cell wall were incubated with Viscozyme and subsequently with proteinase K for cell disruption; this was unnecessary for fragile cells. The addition of sodium thiosulfate to the PCR tube considerably decreased the inhibiting effect of the fixative (iodine) on the PCR and thus allowed for successful single-cell PCR even of long DNA fragments (up to as many as 3,000 base pairs). We further applied the protocol to investigate the dominant SSU rRNA genotypes in distinct flagellate morphospecies originating from different samples. We hypothesized that despite the morphological similarity, protist morphospecies in different habitats or sampled during different seasons are represented by different genotypes. Our results indicate species-specific differences: the two species Ochromonas sp. and Dinobryon divergens were represented by several different genotypes each, and for the latter species, the dominating genotype differed with habitat. In contrast, Dinobryon pediforme, Dinobryon bavaricum, and Synura sphagnicola were exclusively represented by a single genotype each, and the respective genotype was the same in different samples. In summary, our results highlight the significance of molecular variation within protist morphospecies.

  10. Improved Methodology for Identification of Protists and Microalgae from Plankton Samples Preserved in Lugol's Iodine Solution: Combining Microscopic Analysis with Single-Cell PCR▿ †

    Science.gov (United States)

    Auinger, Barbara M.; Pfandl, Karin; Boenigk, Jens

    2008-01-01

    Here we introduce a method for quantitative analysis of planktonic protists and microalgae from preserved field samples combining morphological and small-subunit (SSU) rRNA gene sequence analysis. We linked a microscopic screening with PCR of single cells using field samples preserved with Lugol's iodine solution. Cells possessing a rigid cell wall were incubated with Viscozyme and subsequently with proteinase K for cell disruption; this was unnecessary for fragile cells. The addition of sodium thiosulfate to the PCR tube considerably decreased the inhibiting effect of the fixative (iodine) on the PCR and thus allowed for successful single-cell PCR even of long DNA fragments (up to as many as 3,000 base pairs). We further applied the protocol to investigate the dominant SSU rRNA genotypes in distinct flagellate morphospecies originating from different samples. We hypothesized that despite the morphological similarity, protist morphospecies in different habitats or sampled during different seasons are represented by different genotypes. Our results indicate species-specific differences: the two species Ochromonas sp. and Dinobryon divergens were represented by several different genotypes each, and for the latter species, the dominating genotype differed with habitat. In contrast, Dinobryon pediforme, Dinobryon bavaricum, and Synura sphagnicola were exclusively represented by a single genotype each, and the respective genotype was the same in different samples. In summary, our results highlight the significance of molecular variation within protist morphospecies. PMID:18296536

  11. Hot topic: Bovine milk samples yielding negative or nonspecific results in bacterial culturing--the possible role of PCR-single strand conformation polymorphism in mastitis diagnosis.

    Science.gov (United States)

    Schwaiger, K; Wimmer, M; Huber-Schlenstedt, R; Fehlings, K; Hölzel, C S; Bauer, J

    2012-01-01

    A large proportion of mastitis milk samples yield negative or nonspecific results (i.e., no mastitis pathogen can be identified) in bacterial culturing. Therefore, the culture-independent PCR-single strand conformation polymorphism method was applied to the investigation of bovine mastitis milk samples. In addition to the known mastitis pathogens, the method was suitable for the detection of fastidious bacteria such as Mycoplasma spp., which are often missed by conventional culturing methods. The detection of Helcococcus ovis in 4 samples might indicate an involvement of this species in pathogenesis of bovine mastitis. In conclusion, PCR-single-strand conformation polymorphism is a promising tool for gaining new insights into the bacteriological etiology of mastitis. Copyright © 2012 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  12. [Detection of Coxiella burnetii in dairy cattle bulk tank milk and single tank milk samples by confirmatory testing].

    Science.gov (United States)

    Hilbert, Angela; Andres, Tatjana; Werner, Ralf; Wehr, Roswitha; Fröhlich, Andreas; Conraths, Franz J; Henning, Klaus

    2015-01-01

    Q fever is a worldwide zoonotic disease caused by the pathogen Coxiella (C.) burnetii. A wide range of animal species is susceptible to this intracellular bacterium with great importance in ruminants. Human infections occur mainly by airborne transmission. C burnetii was detected in animal products such as raw milk, raw-milk cheese and butter prepared from raw milk as well as in the meat of infected animals. In cattle milk, the pathogen was detected up to 13 months after calving. The risk of human foodborne C. Burnetii infection is still considered to be low, but cannot be completely ruled out and remains under discussion. The aim of this study was to compare different laboratory diagnostic methods for C. burnetii in milk sample. The bulk tank and individual milk samples were sent and studied at the National Reference Laboratory for Q-fever in the context of confirmatory laboratory testing after clinical suspicion or retesting of previously antibody detection was in the analysis of 888 individual milk samples a match of 93.3% (Cohen-kappa). A total of 173 bulk milk samples and 2,807 individual milk samples from bovine herds for the presence of C. burnetii DNA and antibodies were tested against the pathogen. The pathogen was detected in 62.5% of the bulk milk samples and up to 60% in individual milk samples. The highest proportion of positive bulk milks was determined as 68.3% in 2012. In individual milk samples, the highest proportion of seropositive samples was 62.2%.

  13. Spatiotemporal Dynamics of Cortical Representations during and after Stimulus Presentation

    Directory of Open Access Journals (Sweden)

    Marieke Esther van de Nieuwenhuijzen

    2016-05-01

    Full Text Available Visual perception is a spatiotemporally complex process. In this study, we investigated cortical dynamics during and after stimulus presentation. We observed that visual category information related to the difference between faces and objects became apparent in the occipital lobe after 63 ms. Within the next 110 ms, activation spread out to include the temporal lobe before returning to residing mainly in the occipital lobe again. After stimulus offset, a peak in information was observed, comparable to the peak after stimulus onset. Moreover, similar processes, albeit not identical, seemed to underlie both peaks. Information about the categorical identity of the stimulus remained present until 677 ms after stimulus offset, during which period the stimulus had to be retained in working memory. Activation patterns initially resembled those observed during stimulus presentation. After about 200 ms, however, this representation changed and class-specific activity became more equally distributed over the four lobes. These results show that, although there are common processes underlying stimulus representation both during and after stimulus presentation, these representations change depending on the specific stage of perception and maintenance.

  14. Sample preparation for semivolatile organics analysis of Hanford single-shell tank waste with high nitrate/nitrite and water content

    International Nuclear Information System (INIS)

    Stromatt, R.W.; Hoppe, E.W.; Steele, M.J.

    1993-11-01

    This report describes research work carried out to solve sample preparation problems associated with applying gas chromatography with mass spectrometric detection (GC/MS) to the analysis of single shell tank (SST) samples from Hanford for semivolatile organic compounds. Poor performance was found when applying the procedures based on the U.S. Environmental Protection Agency (EPA), Contract Laboratory Program, Statement of Work (CLP SOW). Analysis work was carried out on simulated drainable liquid modeled after the SST core samples which had evidenced analysis problems. Some work was also conducted on true SST samples. It was found that the pH range was too broad in the original procedure. It was also found that by decreasing the amount of methanol used in the extraction process, problems associated with the formation of an azeotrope phase could be avoided. The authors suggest a new procedure, whose eventual application to a wide array of SST samples will lend itself to better quality control limits

  15. The effect of single twitch and train-of-four stimulation on twitch forces during stable neuromuscular block

    NARCIS (Netherlands)

    van Santen, G; Fidler, [No Value; Houwertjes, MC; Top, WMC; Wierda, JMKH

    2000-01-01

    Objective. We investigated whether the response to a single twitch (ST) stimulus or the first response (T1) to a train-of-four (TOF; 4 stimuli at 2 Hz) stimulus following a stimulus interval of 10 s (i.e., the time between two consecutive ST or TOF stimuli) is influenced by the preceding stimulus in

  16. Variability of the Time Course of Stimulus-Specific Adaptation in the Inferior Colliculus

    Directory of Open Access Journals (Sweden)

    David ePérez-González

    2012-12-01

    Full Text Available Stimulus-specific adaptation (SSA is the ability of some neurons to respond better to rare than to frequent, repetitive stimuli. In the auditory system, it has been found at the level of the midbrain, thalamus and cortex. While previous studies have used the whole overall neuronal response to characterize SSA, here we present a detailed analysis on the variations within the time course of the evoked responses. The extracellular activity of well isolated single neurons from the inferior colliculus (IC was recorded during stimulation using an oddball paradigm, which is able to elicit SSA. At the same time, these responses were evaluated before, during and after the microiontophoretic application of gabazine, a specific antagonist of GABA-A receptors, to study the contribution of inhibition to the responses of these neurons. We then analyzed the difference signal (DS, which is the difference in the PSTH in response to rare and frequent stimuli. We found that, even in a sample of neurons showing strong SSA (i.e., showing larger preference for rare stimuli, the DS was variable and one third of the neurons contained portions that responded significantly better to the frequent stimuli than to the rare. This variability is not observed when averaging the responses of multiple cells. Furthermore, the blockade of GABA-A receptors increased the number of neurons showing portions that responded better to the frequent stimuli, indicating that inhibition in the IC refines and sharpens SSA in the neural responses. 

  17. Single-molecule X-ray free-electron laser imaging : Interconnecting sample orientation with explosion data

    OpenAIRE

    Östlin, Christofer

    2014-01-01

    X-ray crystallography has been around for 100 years and remains the preferred technique for solving molecular structures today. However, its reliance on the production of sufficiently large crystals is limiting, considering that crystallization cannot be achieved for a vast range of biomolecules. A promising way of circumventing this problem is the method of serial femtosecond imaging of single-molecules or nanocrystals utilizing an X-ray free-electron laser. In such an approach, X-ray pulses...

  18. A novel method for single sample multi-axial nanoindentation of hydrated heterogeneous tissues based on testing great white shark jaws.

    Directory of Open Access Journals (Sweden)

    Toni L Ferrara

    Full Text Available Nanomechanical testing methods that are suitable for a range of hydrated tissues are crucial for understanding biological systems. Nanoindentation of tissues can provide valuable insights into biology, tissue engineering and biomimetic design. However, testing hydrated biological samples still remains a significant challenge. Shark jaw cartilage is an ideal substrate for developing a method to test hydrated tissues because it is a unique heterogeneous composite of both mineralized (hard and non-mineralized (soft layers and possesses a jaw geometry that is challenging to test mechanically. The aim of this study is to develop a novel method for obtaining multidirectional nanomechanical properties for both layers of jaw cartilage from a single sample, taken from the great white shark (Carcharodon carcharias. A method for obtaining multidirectional data from a single sample is necessary for examining tissue mechanics in this shark because it is a protected species and hence samples may be difficult to obtain. Results show that this method maintains hydration of samples that would otherwise rapidly dehydrate. Our study is the first analysis of nanomechanical properties of great white shark jaw cartilage. Variation in nanomechanical properties were detected in different orthogonal directions for both layers of jaw cartilage in this species. The data further suggest that the mineralized layer of shark jaw cartilage is less stiff than previously posited. Our method allows multidirectional nanomechanical properties to be obtained from a single, small, hydrated heterogeneous sample. Our technique is therefore suitable for use when specimens are rare, valuable or limited in quantity, such as samples obtained from endangered species or pathological tissues. We also outline a method for tip-to-optic calibration that facilitates nanoindentation of soft biological tissues. Our technique may help address the critical need for a nanomechanical testing method

  19. Classical Conditioning Components of the Orienting Reflex to Words Using Innocuous and Noxious Unconditioned Stimuli Under Different Conditioned Stimulus-Unconditioned Stimulus Intervals

    Science.gov (United States)

    Maltzman, Irving; And Others

    1977-01-01

    Concerns the examination of conditioned stimulus--unconditioned stimulus (CS--UCS) intervals of different lengths. Demonstrates the feasibility of using a forewarned reaction time procedure with an innocuous imperative stimulus for the investigation of classical conditioning. (Editor/RK)

  20. Pigeons learn stimulus identity and stimulus relations when both serve as redundant, relevant cues during same-different discrimination training.

    Science.gov (United States)

    Gibson, Brett M; Wasserman, Edward A

    2003-01-01

    The authors taught pigeons to discriminate displays of 16 identical items from displays of 16 nonidentical items. Unlike most same-different discrimination studies--where only stimulus relations could serve a discriminative function--both the identity of the items and the relations among the items were discriminative features of the displays. The pigeons learned about both stimulus identity and stimulus relations when these 2 sources of information served as redundant, relevant cues. In tests of associative competition, identity cues exerted greater stimulus control than relational cues. These results suggest that the pigeon can respond to both specific stimuli and general relations in the environment.

  1. Towards diffractive imaging with single pulses of FEL radiation. Dynamics within irradiatied samples and their influence on the analysis of imaging data

    International Nuclear Information System (INIS)

    Wang, Fenglin

    2010-08-01

    3D single particle coherent diffraction imaging (CDI) of bioparticles (such as proteins, macromolecules and viruses) is one of the main possible applications of the new generation of light sources: free-electron lasers (FELs), which are now available at FLASH (Hamburg, Germany) and LCLS (Stanford, U.S.A.). The extremely bright and ultrashort FEL pulses potentially enable CDI to achieve high resolution down to subnanometer length scale. However, intense FEL pulses cause serious radiation damage in bioparticles, even during single shots, which may set the resolution limits for CDI with FELs. Currently, since the signal-to-noise ratio is very low for small biological particles, direct experimental study of radiation damage in the single particle imaging is fairly difficult. Single atomic (noble gas) clusters become good objects to reveal effects of radiation damage processes on CDI with FEL radiation. This thesis studies three aspects of the radiation damage problem, which are treated in three independent chapters: (1) Molecular Dynamics simulations to quantitively describe radiation damage processes within irradiated atomic clusters during single pulses; (2) reconstruction analysis of single-shot CDI diffraction patterns of atomic clusters, which may potentially help to understand the radiation damage occurring in biological samples; and (3) testing the effects of coating water layers in CDI, which is supposed to minimize the radiation damage in irradiated bioparticles. (orig.)

  2. Towards diffractive imaging with single pulses of FEL radiation. Dynamics within irradiatied samples and their influence on the analysis of imaging data

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Fenglin

    2010-08-15

    3D single particle coherent diffraction imaging (CDI) of bioparticles (such as proteins, macromolecules and viruses) is one of the main possible applications of the new generation of light sources: free-electron lasers (FELs), which are now available at FLASH (Hamburg, Germany) and LCLS (Stanford, U.S.A.). The extremely bright and ultrashort FEL pulses potentially enable CDI to achieve high resolution down to subnanometer length scale. However, intense FEL pulses cause serious radiation damage in bioparticles, even during single shots, which may set the resolution limits for CDI with FELs. Currently, since the signal-to-noise ratio is very low for small biological particles, direct experimental study of radiation damage in the single particle imaging is fairly difficult. Single atomic (noble gas) clusters become good objects to reveal effects of radiation damage processes on CDI with FEL radiation. This thesis studies three aspects of the radiation damage problem, which are treated in three independent chapters: (1) Molecular Dynamics simulations to quantitively describe radiation damage processes within irradiated atomic clusters during single pulses; (2) reconstruction analysis of single-shot CDI diffraction patterns of atomic clusters, which may potentially help to understand the radiation damage occurring in biological samples; and (3) testing the effects of coating water layers in CDI, which is supposed to minimize the radiation damage in irradiated bioparticles. (orig.)

  3. Stimulus edge effects in the measurement of macular pigment using heterochromatic flicker photometry.

    Science.gov (United States)

    Smollon, William E; Wooten, Billy R; Hammond, Billy R

    2015-11-01

    Heterochromatic flicker photometry (HFP) is the most common technique of measuring macular pigment optical density (MPOD). Some data strongly suggest that HFP samples MPOD specifically at the edge of center-fixated circular stimuli. Other data have led to the conclusion that HFP samples over the entire area of the stimulus. To resolve this disparity, MPOD was measured using HFP and a series of solid discs of varying radii (0.25 to 2.0 deg) and with thin annuli corresponding to the edge of those discs. MPOD assessed with the two methods yielded excellent correspondence and linearity: Y=0.01+0.98X , r=0.96. A second set of experiments showed that if a disc stimulus is adjusted for no-flicker (the standard procedure) and simply reduced in size, no flicker is observed despite the higher level of MPOD in the smaller area. Taken together, these results confirm that MPOD is determined at the edge of the measuring stimulus when using stimulus sizes in the range that is in dispute (up to a radius of 0.75 deg). The basis for this edge effect can be explained by quantitative differences in the spatial-temporal properties of the visual field as a function of angular distance from the fixation point.

  4. Determination of the thermal neutron absorption cross section for rock samples by a single measurement of the time decay constant

    International Nuclear Information System (INIS)

    Krynicka, E.

    1993-01-01

    A calibration method for the determination of the thermal neutron macroscopic mass absorption cross section for rock samples is presented. The standard deviation of the final results is discussed in detail. A big advantage of the presented method is that the calibration curves have been found using the results obtained for a variety of natural rock samples of different stratigraphies and lithologies measured by Czubek's methods. An important part of the paper is a through analysis of the standard deviation of the final result. (author). 13 refs, 11 figs, 5 tabs

  5. Optimal sample size for predicting viability of cabbage and radish seeds based on near infrared spectra of single seeds

    DEFF Research Database (Denmark)

    Shetty, Nisha; Min, Tai-Gi; Gislum, René

    2011-01-01

    The effects of the number of seeds in a training sample set on the ability to predict the viability of cabbage or radish seeds are presented and discussed. The supervised classification method extended canonical variates analysis (ECVA) was used to develop a classification model. Calibration sub...... and radish data. The misclassification rates at optimal sample size were 8%, 6% and 7% for cabbage and 3%, 3% and 2% for radish respectively for random method (averaged for 10 iterations), DUPLEX and CADEX algorithms. This was similar to the misclassification rate of 6% and 2% for cabbage and radish obtained...

  6. Distinct representations of attentional control during voluntary and stimulus-driven shifts across objects and locations.

    Science.gov (United States)

    Stoppel, Christian Michael; Boehler, Carsten Nicolas; Strumpf, Hendrik; Krebs, Ruth Marie; Heinze, Hans-Jochen; Hopf, Jens-Max; Schoenfeld, Mircea Ariel

    2013-06-01

    Efficient interaction with the sensory environment requires the rapid reallocation of attentional resources between spatial locations, perceptual features, and objects. It is still a matter of debate whether one single domain-general network or multiple independent domain-specific networks mediate control during shifts of attention across features, locations, and objects. Here, we employed functional magnetic resonance imaging to directly compare the neural mechanisms controlling attention during voluntary and stimulus-driven shifts across objects and locations. Subjects either maintained or switched voluntarily and involuntarily their attention to objects located at the same or at a different visual location. Our data demonstrate shift-related activity in multiple frontoparietal, extrastriate visual, and default-mode network regions, several of which were commonly recruited by voluntary and stimulus-driven shifts between objects and locations. However, our results also revealed object- and location-selective activations, which, moreover, differed substantially between voluntary and stimulus-driven attention. These results suggest that voluntary and stimulus-driven shifts between objects and locations recruit partially overlapping, but also separable, cortical regions, implicating the parallel existence of domain-independent and domain-specific reconfiguration signals that initiate attention shifts in dependence of particular demands.

  7. Perpendicularity misjudgments caused by contextual stimulus elements.

    Science.gov (United States)

    Bulatov, Aleksandr; Bulatova, Natalija; Surkys, Tadas

    2012-10-15

    It has been demonstrated in previous studies that the illusions of extent of the Brentano type can be explained by the perceptual positional shifts of the stimulus terminators in direction of the centers-of-masses (centroids) of adjacent contextual flanks [Bulatov, A. et al. (2011). Contextual flanks' tilting and magnitude of illusion of extent. Vision Research, 51(1), 58-64]. In the present study, the applicability of the centroid approach to explain the right-angle misjudgments was tested psychophysically using stimuli composed of three small disks (dots) forming an imaginary rectangular triangle. Stimuli comprised the Müller-Lyer wings or line segments (bars) as the contextual distracters rotated around the vertices of the triangle, and changes in the magnitude of the illusion of perpendicularity were measured in a set of experiments. A good resemblance between the experimental data and theoretical predictions obtained strongly supports the suggestion regarding the common "centroid" origin of the illusions of extent of the Brentano type and misperception of the perpendicularity investigated. 2012 Elsevier Ltd. All rights reserved

  8. Prediction of the systemic exposure to oral 9-amino-20(S)-camptothecin using single-sample analysis

    NARCIS (Netherlands)

    Sparreboom, A.; de Jonge, M. J.; Punt, C. J.; Loos, W. J.; Nooter, K.; Stoter, G.; Porro, M. G.; Verweij, J.

    1999-01-01

    The purpose of this study was to develop and validate limited-sampling strategies for prediction of the area under the plasma-concentration time curves (AUCs) of the lactone and total (i. e., lactone plus carboxylate) forms of the novel topoisomerase-I inhibitor 9-amino-20(S)-camptothecin (9-AC).

  9. Prediction of the systemic exposure to oral 9-amino-20(S)-camptothecin using single-sample analysis

    NARCIS (Netherlands)

    A. Sparreboom (Alex); M.J.A. de Jonge (Maja); C.J.A. Punt (Cornelis); W.J. Loos (Walter); K. Nooter (Kees); G. Stoter (Gerrit); M.G. Porro; J. Verweij (Jaap)

    1999-01-01

    textabstractThe purpose of this study was to develop and validate limited-sampling strategies for prediction of the area under the plasma-concentration time curves (AUCs) of the lactone and total (i. e., lactone plus carboxylate) forms of the novel topoisomerase-I

  10. Single Image Super-resolution Using Gaussian Process Regression with Dictionary-based Sampling and Student-t Likelihood.

    Science.gov (United States)

    Wang, Haijun; Gao, Xinbo; Zhang, Kaibing; Li, Jie

    2017-05-03

    Gaussian process regression (GPR) is an effective statistical learning method for modeling non-linear mapping from an observed space to an expected latent space. When applying it to example learning-based super-resolution (SR), two outstanding issues remain. One is its high computational complexity restricts SR application when a large dataset is available for learning task. The other is that the commonly used Gaussian likelihood in GPR is incompatible with the true observation model for SR reconstruction. To alleviate the above two issues, we propose a GPR-based SR method by using dictionary-based sampling and student-t likelihood, called DSGPR. Considering that dictionary atoms effectively span the original training sample space, we adopt a dictionary-based sampling strategy by combining all the neighborhood samples of each atom into a compact representative training subset so as to reduce the computational complexity. Based on statistical tests, we statistically validate that Studentt likelihood is more suitable to build the observation model for SR problem. Extensive experimental results show that the proposed method outperforms other competitors and produces more pleasing details in texture regions.

  11. Mites in dust samples from mattress surfaces from single beds or cribs in the south Brazilian city of Londrina.

    Science.gov (United States)

    da Silva, Dagoberto Ribeiro; Binotti, Raquel Soares; da Silva, Cleide Moreira; de Oliveira, Celso Henrique; Condino-Neto, Antônio; de Capitani, Eduardo Mello

    2005-03-01

    The aim of this study was to investigate the mite fauna in mattresses dust samples from cribs or beds in the south Brazilian city of Londrina, State of Parana. A total of 133 dust samples from upper and lower mattress surfaces, and bed frames were aspirated once from 38 dwellings (18 cribs and 21 beds), and one day nursery (six cribs). A total of 758 mite bodies were counted in slides: 233 (30.7%) from cribs and 525 (69.3%) from beds (pdust mites--mainly Dermatophagoides pteronyssinus, represented 72% and 84% of total mite count in crib and bed dust samples, respectively. The mean HDM body concentration in crib or bed slides were, respectively, 289.9+/-136.7 and 875.0+/-183.6 mites/g. Statistical analysis showed a significantly higher mite bodies count on lower mattress surface compared with upper surface in bed samples only (p=0.025). Data herein show that cribs like mattress have sufficient mite bodies to cause sensitization to humans. The use of mattress covers for cribs and beds should be encouraged in order to avoid allergens exposure. Copyright (c) 2005 Blackwell Munksgaard

  12. Single-shot all-optical sampling oscilloscope using a polarization-maintaining resonator for pulse replication

    Czech Academy of Sciences Publication Activity Database

    Komanec, M.; Honzátko, Pavel; Zvánovec, S.

    2010-01-01

    Roč. 52, č. 11 (2010), s. 2452-2456 ISSN 0895-2477 R&D Projects: GA AV ČR 1ET300670502 Institutional research plan: CEZ:AV0Z20670512 Keywords : optical sampling oscilloscope * four-wave mixing * fiber pulse replicator * highly nonlinear fiber Subject RIV: BH - Optics, Masers, Lasers Impact factor: 0.656, year: 2010

  13. Simple methodology to directly genotype Trypanosoma cruzi discrete typing units in single and mixed infections from human blood samples.

    Science.gov (United States)

    Bontempi, Iván A; Bizai, María L; Ortiz, Sylvia; Manattini, Silvia; Fabbro, Diana; Solari, Aldo; Diez, Cristina

    2016-09-01

    Different DNA markers to genotype Trypanosoma cruzi are now available. However, due to the low quantity of parasites present in biological samples, DNA markers with high copy number like kinetoplast minicircles are needed. The aim of this study was to complete a DNA assay called minicircle lineage specific-PCR (MLS-PCR) previously developed to genotype the T. cruzi DTUs TcV and TcVI, in order to genotype DTUs TcI and TcII and to improve TcVI detection. We screened kinetoplast minicircle hypervariable sequences from cloned PCR products from reference strains belonging to the mentioned DTUs using specific kDNA probes. With the four highly specific sequences selected, we designed primers to be used in the MLS-PCR to directly genotype T. cruzi from biological samples. High specificity and sensitivity were obtained when we evaluated the new approach for TcI, TcII, TcV and TcVI genotyping in twenty two T. cruzi reference strains. Afterward, we compared it with hybridization tests using specific kDNA probes in 32 blood samples from chronic chagasic patients from North Eastern Argentina. With both tests we were able to genotype 94% of the samples and the concordance between them was very good (kappa=0.855). The most frequent T. cruzi DTUs detected were TcV and TcVI, followed by TcII and much lower TcI. A unique T. cruzi DTU was detected in 18 samples meantime more than one in the remaining; being TcV and TcVI the most frequent association. A high percentage of mixed detections were obtained with both assays and its impact was discussed. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. A Computer Tutorial on the Principles of Stimulus Generalization.

    Science.gov (United States)

    Graham, Robert B.

    1998-01-01

    Describes a computer tutorial that teaches the fundamentals of stimulus generalization in operant learning. Concepts covered include reinforcement, discrimination learning, stimulus continua, generalization, generalization gradients, and peak shift. The tutorial also reviews applications in human and animal situations. The content is appropriate…

  15. Water absorption kinetics in different wettability conditions studied at pore and sample scales in porous media by NMR with portable single-sided and laboratory imaging devices

    Science.gov (United States)

    Bortolotti, V.; Camaiti, M.; Casieri, C.; De Luca, F.; Fantazzini, P.; Terenzi, C.

    2006-08-01

    NMR relaxation time distributions of water 1H obtained by a portable single-sided surface device have been compared with MRI internal images obtained with a laboratory imaging apparatus on the same biocalcarenite (Lecce Stone) samples during capillary water uptake. The aim of this work was to check the ability of NMR methods to quantitatively follow the absorption phenomenon under different wettability conditions of the internal pore surfaces. Stone wettability changes were obtained by capillary absorption of a chloroform solution of Paraloid PB72, a hydrophobic acrylic resin frequently used to protect monuments and buildings, through one face of each sample. Both relaxation and imaging data have been found in good quantitative agreement each other and with masses of water determined by weighing the samples. In particular the Washburn model of water capillary rise applied to the imaging data allowed us to quantify the sorptivity in both treated and untreated samples. Combining relaxation and imaging data, a synergetic improvement of our understanding of the water absorption kinetics at both pore and sample scales is obtained. Since relaxation data have been taken over the course of time without interrupting the absorption process, simply by keeping the portable device on the surface opposite to the absorption, the results show that the single-sided NMR technique is a powerful tool for in situ evaluation of water-repellent treatments frequently used for consolidation and/or protection of stone artifacts.

  16. Determination of the optional time for taking blood samples by single intravenous injection of 3H-leucine

    International Nuclear Information System (INIS)

    Meng Delian; Yao Junhu; Lu Jinyin; Wu Xiaobin; Liu Jun

    2003-01-01

    Twenty four young hens (1.5 kg of body weight, BW) were randomly divided into 4 groups. Every group was diet free (FAS) or force-fed a nitrogen-free diet (NFD) or the diet with 20% crude protein in which soybean meal or cotton seed meal was the sole nitrogen source (30 g DM/kg BW). 30 μCi 3 H-Leu/kg BW was intravenously injected into all birds just after force-fed or on fasting. Venous blood samples were taken at 5, 30 min, 4,24,36 and 48h after injection. The excreta during the whole period of 48h after injection was collected. Special radioactivities of nonprotein plasma at every time point and excreta were measured. The optional time of taking blood samples was 20-24 hours after injected 3 H-Leu

  17. Forensic Sampling and Analysis from a Single Substrate: Surface-Enhanced Raman Spectroscopy Followed by Paper Spray Mass Spectrometry.

    Science.gov (United States)

    Fedick, Patrick W; Bills, Brandon J; Manicke, Nicholas E; Cooks, R Graham

    2017-10-17

    Sample preparation is the most common bottleneck in the analysis and processing of forensic evidence. Time-consuming steps in many forensic tests involve complex separations, such as liquid and gas chromatography or various types of extraction techniques, typically coupled with mass spectrometry (e.g., LC-MS). Ambient ionization ameliorates these slow steps by reducing or even eliminating sample preparation. While some ambient ionization techniques have been adopted by the forensic community, there is significant resistance to discarding chromatography as most forensic analyses require both an identification and a confirmation technique. Here, we describe the use of a paper substrate, the surface of which has been inkjet printed with silver nanoparticles, for surface enhanced Raman spectroscopy (SERS). The same substrate can also act as the paper substrate for paper spray mass spectrometry. The coupling of SERS and paper spray ionization creates a quick, forensically feasible combination.

  18. Rapid Treponema pallidum clearance from blood and ulcer samples following single dose benzathine penicillin treatment of early syphilis.

    Science.gov (United States)

    Tipple, Craig; Jones, Rachael; McClure, Myra; Taylor, Graham

    2015-02-01

    Currently, the efficacy of syphilis treatment is measured with anti-lipid antibody tests. These can take months to indicate cure and, as a result, syphilis treatment trials require long periods of follow-up. The causative organism, Treponema pallidum (T. pallidum), is detectable in the infectious lesions of early syphilis using DNA amplification. Bacteraemia can likewise be identified, typically in more active disease. We hypothesise that bacterial clearance from blood and ulcers will predict early the standard serology-measured treatment response and have developed a qPCR assay that could monitor this clearance directly in patients with infectious syphilis. Patients with early syphilis were given an intramuscular dose of benzathine penicillin. To investigate the appropriate sampling timeframe samples of blood and ulcer exudate were collected intensively for T. pallidum DNA (tpp047 gene) and RNA (16S rRNA) quantification. Sampling ended when two consecutive PCRs were negative. Four males were recruited. The mean peak level of T. pallidum DNA was 1626 copies/ml whole blood and the mean clearance half-life was 5.7 hours (std. dev. 0.53). The mean peak of 16S rRNA was 8879 copies/ml whole blood with a clearance half-life of 3.9 hours (std. dev. 0.84). From an ulcer, pre-treatment, 67,400 T. pallidum DNA copies and 7.08 x 107 16S rRNA copies were detected per absorbance strip and the clearance half-lives were 3.2 and 4.1 hours, respectively. Overall, T. pallidum nucleic acids were not detected in any sample collected more than 56 hours (range 20-56) after treatment. All patients achieved serologic cure. In patients with active early syphilis, measuring T. pallidum levels in blood and ulcer exudate may be a useful measure of treatment success in therapeutic trials. These laboratory findings need confirmation on a larger scale and in patients receiving different therapies.

  19. A comparison of three fecal steroid metabolites for pregnancy detection used with single sampling in bighorn sheep (Ovis canadensis)

    Science.gov (United States)

    Schoenecker, K.A.; Lyda, R.O.; Kirkpatrick, J.

    2004-01-01

    We compared three fecal steroid metabolite assays for their usefulness in detecting pregnancy among free-ranging Rocky Mountain bighorn sheep (Ovis canadensis canadensis) from Bighorn Canyon National Recreation Area, Wyoming and Montana (USA) and captive bighorn ewes at ZooMontana in Billings, Montana. Fecal samples were collected from 11 free-ranging, radio-collared bighorn ewes in late January–May 2001 and from 20 free-ranging, radio-collared ewes in late March to mid-May 2002. Free-ranging ewes were monitored the following spring to determine whether or not they lambed. In addition, two captive ewes were studied at Zoo-Montana. With three exceptions, free-ranging bighorn ewes that produced lambs had nonspecific progesterone metabolite (iPdG) levels of >1,800 ng/g feces and iPdG levels >7,000 ng/gm feces when samples were collected between early March and mid-May Samples collected earlier in the year were inconclusive. One false negative was suspected to be the result of sample collection error. Of the captive ewes, nonspecific pregnanediol-3α–glucuronide (PdG) and iPdG followed a predictable curve over the course of the 180-day pregnancies. We conclude that estrone conjugates are not useful in diagnosing pregnancy; however, fecal steroid analysis of PdG and iPdG can be used to accurately determine pregnancy and reproductive function in bighorn sheep. This holds great potential as a noninvasive technique for understanding the role of reproductive disease in wild bighorn sheep.

  20. Identification and genetic characterization of a novel circular single-stranded DNA virus in a human upper respiratory tract sample.

    Science.gov (United States)

    Cui, Lunbiao; Wu, Binyao; Zhu, Xiaojuan; Guo, Xiling; Ge, Yiyue; Zhao, Kangchen; Qi, Xian; Shi, Zhiyang; Zhu, Fengcai; Sun, Lixin; Zhou, Minghao

    2017-11-01

    Metagenomic analysis through high-throughput sequencing is a tool for detecting both known and novel viruses. Using this technique, a novel circular single-stranded DNA (ssDNA) virus genome was discovered in respiratory secretions from a febrile traveler. The virus, named human respiratory-associated PSCV-5-like virus (HRAPLV), has a genome comprising 3,018 bases, with two major putative ORFs inversely encoding capsid (Cap) and replicase (Rep) protein and separated by two intergenic regions. One stem-loop structure was predicted in the larger intergenic region (LIR). The predicted amino acid sequences of the Cap and Rep proteins of HRAPLV showed highest identity to those of porcine stool-associated circular virus 5 isolate CP3 (PoSCV 5) (53.0% and 48.9%, respectively). The host tropism of the virus is unknown, and further study is warranted to determine whether this novel virus is associated with human disease.

  1. Multifaceted empathy of healthy volunteers after single doses of MDMA: A pooled sample of placebo-controlled studies.

    Science.gov (United States)

    Kuypers, Kim Pc; Dolder, Patrick C; Ramaekers, Johannes G; Liechti, Matthias E

    2017-05-01

    Previous placebo-controlled experimental studies have shown that a single dose of MDMA can increase emotional empathy in the multifaceted empathy test (MET) without affecting cognitive empathy. Although sufficiently powered to detect main effects of MDMA, these studies were generally underpowered to also validly assess contributions of additional parameters, such as sex, drug use history, trait empathy and MDMA or oxytocin plasma concentrations. The present study examined the robustness of the MDMA effect on empathy and investigated the moderating role of these additional parameters. Participants ( n = 118) from six placebo-controlled within-subject studies and two laboratories were included in the present pooled analysis. Empathy (MET), MDMA and oxytocin plasma concentrations were assessed after oral administration of MDMA (single dose, 75 or 125 mg). Trait empathy was assessed using the interpersonal reactivity index. We confirmed that MDMA increased emotional empathy at both doses without affecting cognitive empathy. This MDMA-related increase in empathy was most pronounced during presentation of positive emotions as compared with negative emotions. MDMA-induced empathy enhancement was positively related to MDMA blood concentrations measured before the test, but independent of sex, drug use history and trait empathy. Oxytocin concentrations increased after MDMA administration but were not associated with behavioral effects. The MDMA effects on emotional empathy were stable across laboratories and doses. Sex did not play a moderating role in this effect, and oxytocin levels, trait empathy and drug use history were also unrelated. Acute drug exposure was of significant relevance in the MDMA-induced emotional empathy elevation.

  2. Efficient sampling of reversible cross-linking polymers: Self-assembly of single-chain polymeric nanoparticles

    Science.gov (United States)

    Oyarzún, Bernardo; Mognetti, Bortolo Matteo

    2018-03-01

    We present a new simulation technique to study systems of polymers functionalized by reactive sites that bind/unbind forming reversible linkages. Functionalized polymers feature self-assembly and responsive properties that are unmatched by the systems lacking selective interactions. The scales at which the functional properties of these materials emerge are difficult to model, especially in the reversible regime where such properties result from many binding/unbinding events. This difficulty is related to large entropic barriers associated with the formation of intra-molecular loops. In this work, we present a simulation scheme that sidesteps configurational costs by dedicated Monte Carlo moves capable of binding/unbinding reactive sites in a single step. Cross-linking reactions are implemented by trial moves that reconstruct chain sections attempting, at the same time, a dimerization reaction between pairs of reactive sites. The model is parametrized by the reaction equilibrium constant of the reactive species free in solution. This quantity can be obtained by means of experiments or atomistic/quantum simulations. We use the proposed methodology to study the self-assembly of single-chain polymeric nanoparticles, starting from flexible precursors carrying regularly or randomly distributed reactive sites. We focus on understanding differences in the morphology of chain nanoparticles when linkages are reversible as compared to the well-studied case of irreversible reactions. Intriguingly, we find that the size of regularly functionalized chains, in good solvent conditions, is non-monotonous as a function of the degree of functionalization. We clarify how this result follows from excluded volume interactions and is peculiar of reversible linkages and regular functionalizations.

  3. Evolving microstructure, magnetic properties and phase transition in a mechanically alloyed Ni0.5Zn0.5Fe2O4 single sample

    Science.gov (United States)

    Ismail, Ismayadi; Hashim, Mansor; Kanagesan, Samikannu; Ibrahim, Idza Riati; Nazlan, Rodziah; Wan Ab Rahman, Wan Norailiana; Abdullah, Nor Hapishah; Mohd Idris, Fadzidah; Bahmanrokh, Ghazaleh; Shafie, Mohd Shamsul Ezzad; Manap, Masni

    2014-02-01

    We report on an investigation to unravel the dependence of magnetic properties on microstructure while they evolve in parallel under the influence of sintering temperature of a single sample of Ni0.5Zn0.5Fe2O4 synthesized via mechanical alloying. A single sample, instead of the normally practiced approach of using multiple samples, was sintered at various sintering temperatures from 500 °C to 1400 °C. The morphology of the samples was studied by means of scanning electron microscopy (SEM) equipped with EDX; density measurement was conducted using the Archimedes principle; and hysteresis measurement was carried out using a B-H hysteresisgraph system. XRD data showed that the first appearance of a single phase was at 800 °C and an amorphous phase was traced at lower sintering temperatures. We correlated the microstructure and the magnetic properties and showed that the important grain-size threshold for the appearance of significant ordered magnetism (mainly ferromagnetism) was about ≥0.3 µm. We found that there were three stages of magnetic phase evolution produced via the sintering process with increasing temperatures. The first stage was dominated by paramagnetic states with some superparamagnetic behavior; the second stage was influenced by moderately ferromagnetic states and some paramagnetic states; and the third stage consisted of strongly ferromagnetic states with negligible paramagnetic states. We found that three factors sensitively influenced the sample's content of ordered magnetism—the ferrite-phase crystallinity degree, the number of grains above the critical grain size and the number of large enough grains for domain wall accommodation.

  4. Ligand-directed trafficking of receptor stimulus.

    Science.gov (United States)

    Chilmonczyk, Zdzisław; Bojarski, Andrzej J; Sylte, Ingebrigt

    2014-12-01

    GPCRs are seven transmembrane-spanning receptors that convey specific extracellular stimuli to intracellular signalling. They represent the largest family of cell surface proteins that are therapeutically targeted. According to the traditional two-state model of receptor theory, GPCRs were considered as operating in equilibrium between two functional conformations, an active (R*) and inactive (R) state. Thus, it was assumed that a GPCR can exist either in an "off" or "on" conformation causing either no activation or equal activation of all its signalling pathways. Over the past several years it has become evident that this model is too simple and that GPCR signalling is far more complex. Different studies have presented a multistate model of receptor activation in which ligand-specific receptor conformations are able to differentiate between distinct signalling partners. Recent data show that beside G proteins numerous other proteins, such as β-arrestins and kinases, may interact with GPCRs and activate intracellular signalling pathways. GPCR activation may therefore involve receptor desensitization, coupling to multiple G proteins, Gα or Gβγ signalling, and pathway activation that is independent of G proteins. This latter effect leads to agonist "functional selectivity" (also called ligand-directed receptor trafficking, stimulus trafficking, biased agonism, biased signalling), and agonist intervention with functional selectivity may improve the therapy. Many commercially available drugs with beneficial efficacy also show various undesirable side effects. Further studies of biased signalling might facilitate our understanding of the side effects of current drugs and take us to new avenues to efficiently design pathway-specific medications. Copyright © 2014 Institute of Pharmacology, Polish Academy of Sciences. Published by Elsevier Urban & Partner Sp. z o.o. All rights reserved.

  5. A single laboratory setup for investigating the anisotropy of both seismic and electrical properties in core samples

    Science.gov (United States)

    David, Christian; Robion, Philippe; Louis, Laurent

    2017-09-01

    A fully automated versatile device is presented for analysing the anisotropy of both seismic and electrical properties on cylindrical rock samples. Initially devoted to the study of P-wave velocity anisotropy (APV), the system has been upgraded to allow the measurement of electrical conductivity anisotropy (AEC) as well. The improved setup allows for the estimation of the APV and AEC, from measurements across multiple diameters with an angular spacing selected by the operator. In order to determine the APV simplified tensor and the true AEC tensor, at least three mutually orthogonal samples are required. Switching from velocity to electrical measurements only requires replacing the pair of ultrasonic transducers by a pair of electrodes. Whereas the procedure is quite straightforward for the P-wave velocity analysis, different calibration steps and approximations are required in the processing of the electrical data. As an example the methodology was applied to a set of two rocks, the Leopard and the Castlegate sandstones, for which the APV and AEC are compared in a unified scheme. Good agreement was found between the orientation of the symmetry axes for both properties, suggesting that in the studied rocks pore space anisotropy accounts for both velocity and electrical anisotropy. This methodology can also be incorporated into a core analysis workflow to obtain a first-hand assessment of the rock fabric orientation and anisotropy with respect to seismic and transport properties. The information thus obtained can be used as a screening step for sampling and stress testing as well as for direct core to log integration and cross-property correlations.

  6. Rapid Treponema pallidum clearance from blood and ulcer samples following single dose benzathine penicillin treatment of early syphilis.

    Directory of Open Access Journals (Sweden)

    Craig Tipple

    2015-02-01

    Full Text Available Currently, the efficacy of syphilis treatment is measured with anti-lipid antibody tests. These can take months to indicate cure and, as a result, syphilis treatment trials require long periods of follow-up. The causative organism, Treponema pallidum (T. pallidum, is detectable in the infectious lesions of early syphilis using DNA amplification. Bacteraemia can likewise be identified, typically in more active disease. We hypothesise that bacterial clearance from blood and ulcers will predict early the standard serology-measured treatment response and have developed a qPCR assay that could monitor this clearance directly in patients with infectious syphilis. Patients with early syphilis were given an intramuscular dose of benzathine penicillin. To investigate the appropriate sampling timeframe samples of blood and ulcer exudate were collected intensively for T. pallidum DNA (tpp047 gene and RNA (16S rRNA quantification. Sampling ended when two consecutive PCRs were negative. Four males were recruited. The mean peak level of T. pallidum DNA was 1626 copies/ml whole blood and the mean clearance half-life was 5.7 hours (std. dev. 0.53. The mean peak of 16S rRNA was 8879 copies/ml whole blood with a clearance half-life of 3.9 hours (std. dev. 0.84. From an ulcer, pre-treatment, 67,400 T. pallidum DNA copies and 7.08 x 107 16S rRNA copies were detected per absorbance strip and the clearance half-lives were 3.2 and 4.1 hours, respectively. Overall, T. pallidum nucleic acids were not detected in any sample collected more than 56 hours (range 20-56 after treatment. All patients achieved serologic cure. In patients with active early syphilis, measuring T. pallidum levels in blood and ulcer exudate may be a useful measure of treatment success in therapeutic trials. These laboratory findings need confirmation on a larger scale and in patients receiving different therapies.

  7. Single-particle characterization of ice-nucleating particles and ice particles residuals sampled by three different techniques

    Science.gov (United States)

    Kandler, Konrad; Worringen, Annette; Benker, Nathalie; Dirsch, Thomas; Mertes, Stephan; Schenk, Ludwig; Kästner, Udo; Frank, Fabian; Nillius, Björn; Bundke, Ulrich; Rose, Diana; Curtius, Joachim; Kupiszewski, Piotr; Weingartner, Ernest; Vochezer, Paul; Schneider, Johannes; Schmidt, Susan; Weinbruch, Stephan; Ebert, Martin

    2015-04-01

    During January/February 2013, at the High Alpine Research Station Jungfraujoch a measurement campaign was carried out, which was centered on atmospheric ice-nucleating particles (INP) and ice particle residuals (IPR). Three different techniques for separation of INP and IPR from the non-ice-active particles are compared. The Ice Selective Inlet (ISI) and the Ice Counterflow Virtual Impactor (Ice-CVI) sample ice particles from mixed phase clouds and allow for the analysis of the residuals. The combination of the Fast Ice Nucleus Chamber (FINCH) and the Ice Nuclei Pumped Counterflow Virtual Impactor (IN-PCVI) provides ice-activating conditions to aerosol particles and extracts the activated INP for analysis. Collected particles were analyzed by scanning electron microscopy and energy-dispersive X-ray microanalysis to determine size, chemical composition and mixing state. All INP/IPR-separating techniques had considerable abundances (median 20 - 70 %) of instrumental contamination artifacts (ISI: Si-O spheres, probably calibration aerosol; Ice-CVI: Al-O particles; FINCH+IN-PCVI: steel particles). Also, potential sampling artifacts (e.g., pure soluble material) occurred with a median abundance of metal oxides were the major INP/IPR particle types separated by all three techniques. Soot was a minor contributor. Lead was detected in less than 10 % of the particles, of which the majority were internal mixtures with other particle types. Sea-salt and sulfates were identified by all three methods as INP/IPR. Most samples showed a maximum of the INP/IPR size distribution at 400 nm geometric diameter. In a few cases, a second super-micron maximum was identified. Soot/carbonaceous material and metal oxides were present mainly in the submicron range. ISI and FINCH yielded silicates and Ca-rich particles mainly with diameters above 1 µm, while the Ice-CVI also separated many submicron IPR. As strictly parallel sampling could not be performed, a part of the discrepancies between

  8. Two-dimensional strandness-dependent electrophoresis: a method to characterize single-stranded DNA, double-stranded DNA, and RNA-DNA hybrids in complex samples.

    Science.gov (United States)

    Gunnarsson, Gudmundur H; Gudmundsson, Bjarki; Thormar, Hans G; Alfredsson, Arni; Jonsson, Jon J

    2006-03-01

    We describe two-dimensional strandness-dependent electrophoresis (2D-SDE) for quantification and length distribution analysis of single-stranded (ss) DNA fragments, double-stranded (ds) DNA fragments, RNA-DNA hybrids, and nicked DNA fragments in complex samples. In the first dimension nucleic acid molecules are separated based on strandness and length in the presence of 7 M urea. After the first-dimension electrophoresis all nucleic acid fragments are heat denatured in the gel. During the second-dimension electrophoresis all nucleic acid fragments are single-stranded and migrate according to length. 2D-SDE takes about 90 min and requires only basic skills and equipment. We show that 2D-SDE has many applications in analyzing complex nucleic acid samples including (1) estimation of renaturation efficiency and kinetics, (2) monitoring cDNA synthesis, (3) detection of nicked DNA fragments, and (4) estimation of quality and in vitro damage of nucleic acid samples. Results from 2D-SDE should be useful to validate techniques such as complex polymerase chain reaction, subtractive hybridization, cDNA synthesis, cDNA normalization, and microarray analysis. 2D-SDE could also be used, e.g., to characterize biological nucleic acid samples. Information obtained with 2D-SDE cannot be readily obtained with other methods. 2D-SDE can be used for preparative isolation of ssDNA fragments, dsDNA fragments, and RNA-DNA hybrids.

  9. Aerobic stimulus induced by virtual reality games in stroke survivors.

    Science.gov (United States)

    Silva de Sousa, Julio Cesar; Torriani-Pasin, Camila; Tosi, Amanda Barboza; Fecchio, Rafael Yokoyama; Riani da Costa, Luiz Augusto; Forjaz, Cláudia Lúcia de Moraes

    2018-02-08

    To evaluate whether virtual reality games (VRG) in stroke survivors produce significant and reproducible heart rate (HR) and oxygen consumption (VO 2 ) responses during their execution, corresponding to an intensity between the anaerobic threshold (AT) and the respiratory compensation point (RCP). Single subjects repeated measure design SETTING: Stroke survivors registered from a rehabilitation program PARTICIPANTS: Twelve chronic hemiparetic stroke survivors (10 men, 58 ± 12 years) rated at 3 or 4 in the Functional Ambulation Categories (FAC). Subjects underwent, in a random order, two identical sessions of VRG (console Xbox360+Kinect) and one control session (CONT - 38 min watching a movie). The VRG sessions were composed by four sets of VRG (3 min of Boxing, 1 min for changing the game and 4 min of Tennis) interspaced by 2 min of rest. HR and VO 2 were measured during the experimental sessions and compared to HR and VO 2 obtained at AT and RCP assessed in a maximal cardiopulmonary exercise test. HR and VO 2 during VRG presented good reproducibility (intraclass correlation coefficient > 0.91 and > 0.85 and coefficient of variation games of the console XBox360+Kinect promotes reproducible responses of HR and VO 2 that corresponded, respectively, to AT and below AT, characterizing a low intensity aerobic stimulus. Copyright © 2018. Published by Elsevier Inc.

  10. Autonomous stimulus triggered self-healing in smart structural composites

    International Nuclear Information System (INIS)

    Norris, C J; White, J A P; McCombe, G; Chatterjee, P; Bond, I P; Trask, R S

    2012-01-01

    Inspired by the ability of biological systems to sense and autonomously heal damage, this research has successfully demonstrated the first autonomous, stimulus triggered, self-healing system in a structural composite material. Both the sensing and healing mechanisms are reliant on microvascular channels incorporated within a laminated composite material. For the triggering mechanism, a single air filled vessel was pressurized, sealed and monitored. Upon drop weight impact (10 J), delamination and microcrack connectivity between the pressurized vessel and those open to ambient led to a pressure loss which, with the use of a suitable sensor, triggered a pump to deliver a healing agent to the damage zone. Using this autonomous healing approach, near full recovery of post-impact compression strength was achieved (94% on average). A simplified alternative system with healing agent continuously flowing through the vessels, akin to blood flow, was found to offer 100% recovery of the material’s virgin strength. Optical microscopy and ultrasonic C-scanning provided further evidence of large-scale infusion of matrix damage with the healing agent. The successful implementation of this bioinspired technology could substantially enhance the integrity and reliability of aerospace structures, whilst offering benefits through improved performance/weight ratios and extended lifetimes. (paper)

  11. Simultaneous estimation of population receptive field and hemodynamic parameters from single point BOLD responses using Metropolis-Hastings sampling.

    Science.gov (United States)

    Adaszewski, Stanisław; Slater, David; Melie-Garcia, Lester; Draganski, Bogdan; Bogorodzki, Piotr

    2018-01-30

    We introduce a new approach to Bayesian pRF model estimation using Markov Chain Monte Carlo (MCMC) sampling for simultaneous estimation of pRF and hemodynamic parameters. To obtain high performance on commonly accessible hardware we present a novel heuristic consisting of interpolation between precomputed responses for predetermined stimuli and a large cross-section of receptive field parameters. We investigate the validity of the proposed approach with respect to MCMC convergence, tuning and biases. We compare different combinations of pRF - Compressive Spatial Summation (CSS), Dumoulin-Wandell (DW) and hemodynamic (5-parameter and 3-parameter Balloon-Windkessel) models within our framework with and without the usage of the new heuristic. We evaluate estimation consistency and log probability across models. We perform as well a comparison of one model with and without lookup table within the RStan framework using its No-U-Turn Sampler. We present accelerated computation of whole-ROI parameters for one subject. Finally, we discuss risks and limitations associated with the usage of the new heuristic as well as the means of resolving them. We found that the new algorithm is a valid sampling approach to joint pRF/hemodynamic parameter estimation and that it exhibits very high performance. Copyright © 2018. Published by Elsevier Inc.

  12. Single-particle characterization of ice-nucleating particles and ice particle residuals sampled by three different techniques

    Science.gov (United States)

    Worringen, A.; Kandler, K.; Benker, N.; Dirsch, T.; Mertes, S.; Schenk, L.; Kästner, U.; Frank, F.; Nillius, B.; Bundke, U.; Rose, D.; Curtius, J.; Kupiszewski, P.; Weingartner, E.; Vochezer, P.; Schneider, J.; Schmidt, S.; Weinbruch, S.; Ebert, M.

    2015-04-01

    In the present work, three different techniques to separate ice-nucleating particles (INPs) as well as ice particle residuals (IPRs) from non-ice-active particles are compared. The Ice Selective Inlet (ISI) and the Ice Counterflow Virtual Impactor (Ice-CVI) sample ice particles from mixed-phase clouds and allow after evaporation in the instrument for the analysis of the residuals. The Fast Ice Nucleus Chamber (FINCH) coupled with the Ice Nuclei Pumped Counterflow Virtual Impactor (IN-PCVI) provides ice-activating conditions to aerosol particles and extracts the activated particles for analysis. The instruments were run during a joint field campaign which took place in January and February 2013 at the High Alpine Research Station Jungfraujoch (Switzerland). INPs and IPRs were analyzed offline by scanning electron microscopy and energy-dispersive X-ray microanalysis to determine their size, chemical composition and mixing state. Online analysis of the size and chemical composition of INP activated in FINCH was performed by laser ablation mass spectrometry. With all three INP/IPR separation techniques high abundances (median 20-70%) of instrumental contamination artifacts were observed (ISI: Si-O spheres, probably calibration aerosol; Ice-CVI: Al-O particles; FINCH + IN-PCVI: steel particles). After removal of the instrumental contamination particles, silicates, Ca-rich particles, carbonaceous material and metal oxides were the major INP/IPR particle types obtained by all three techniques. In addition, considerable amounts (median abundance mostly a few percent) of soluble material (e.g., sea salt, sulfates) were observed. As these soluble particles are often not expected to act as INP/IPR, we consider them as potential measurement artifacts. Minor types of INP/IPR include soot and Pb-bearing particles. The Pb-bearing particles are mainly present as an internal mixture with other particle types. Most samples showed a maximum of the INP/IPR size distribution at 200

  13. Stimulus-dependent EEG activity reflects internal updating of tactile working memory in humans.

    Science.gov (United States)

    Spitzer, Bernhard; Blankenburg, Felix

    2011-05-17

    Despite recent advances in uncovering the neural signature of tactile working memory processing in animals and humans, the representation of internally modified somatosensory working memory content has not been studied so far. Here, recording EEG in human participants (n = 25) performing a modified delayed match-to-sample task allowed us to disambiguate internally driven memory processing from encoding-related delay activity. After presentation of two distinct vibrotactile frequencies to different index fingers, a visual cue indicated which of the two previous stimuli had to be maintained in working memory throughout a retention interval for subsequent frequency discrimination against a probe stimulus. During cued stimulus maintenance, α activity (8-13 Hz) over early somatosensory cortices was lateralized according to the cued tactile stimulus, even though the location of the stimuli was task irrelevant. The task-relevant memory content, in contrast, was found to be represented in right prefrontal cortex. The key finding was that the visually presented instructions triggered systematic modulations of prefrontal β-band activity (20-25 Hz), which selectively reflected the to-be-maintained frequency of the cued tactile vibration. The results expand previous evidence for parametric representations of vibrotactile frequency in the prefrontal cortex and corroborate a central role of dynamic β-band synchronization during active processing of an analog stimulus quantity in human working memory. In particular, our findings suggest that such processing supports not only sustained maintenance but also purposeful modification and updating of the task-relevant working memory contents.

  14. A Single-Chip 64-Channel Ultrasound RX-Beamformer Including Analog Front-End and an LUT for Non-Uniform ADC-Sample-Clock Generation.

    Science.gov (United States)

    Kim, Yoon-Jee; Cho, Sung-Eun; Um, Ji-Yong; Chae, Min-Kyun; Bang, Jihoon; Song, Jongkeun; Jeon, Taeho; Kim, Byungsub; Sim, Jae-Yoon; Park, Hong-June

    2017-02-01

    A 64-channel RX digital beamformer was implemented in a single chip for 3-D ultrasound medical imaging using 2-D phased-array transducers. The RX beamformer chip includes 64 analog front-end branches including 64 non-uniform sampling ADCs, a FIFO/Adder, and an on-chip look-up table (LUT). The LUT stores the information on the rising edge timing of the non-uniform ADC sampling clocks. To include the LUT inside the beamformer chip, the LUT size was reduced by around 240 times by approximating an ADC-sample-time profile w.r.t. focal points (FP) along a scanline (SL) for a channel into a piece-wise linear form. The maximum error between the approximated and accurate sample times of ADC is eight times the sample time resolution (Ts) that is 1/32 of the ultrasound signal period in this work. The non-uniform sampling reduces the FIFO size required for digital beamforming by around 20 times. By applying a 9-dot image from Field-II program and 2-D ultrasound phantom images to the fabricated RX beamformer chip, the original images were successfully reconstructed from the measured output. The chip in a 0.13-um CMOS occupies 30.25 [Formula: see text] and consumes 605 mW.

  15. Functional interplay between stimulus-oriented and stimulus-independent attending during a prospective memory task.

    Science.gov (United States)

    Barban, Francesco; Carlesimo, Giovanni Augusto; Macaluso, Emiliano; Caltagirone, Carlo; Costa, Alberto

    2014-01-01

    Recent studies have suggested that medial (medBA10) and lateral (latBA10) portions of the Brodmann area 10 subserve respectively stimulus-oriented (SO) and stimulus-independent (SI) attending during prospective memory (PM) tasks. We investigated this dissociation by manipulating the saliency (SO) and the memory load (SI) of PM cues. Sixteen healthy subjects participated to a functional imaging protocol with a 2×2×2 experimental design, including the factors: task (ongoing target vs. PM cue), Saliency (high vs. low; with targets/cues either embedded or standing out from distracters), and memory load (high vs. low; with 1 or 4 possible PM targets). We localized the medBA10 and latBA10 by means of a localizer task. In medBA10 we found a significant main effects of high Saliency and low memory load; whereas in the left latBA10, we found a significant task×load interaction, with maximal activation for PM cues presented in the high load condition. These results are in agreement with the gateway hypothesis: during a PM task medBA10 biases attention toward external salient stimuli, SO attending, while latBA10 biases attention toward internal mnemonic representations, SI attending. Additional whole-brain analyses highlighted activation of other areas besides BA10, consistent with recent proposals that emphasise the role of distributed networks during PM performance. © 2013 Published by Elsevier Ltd.

  16. A computational study of stimulus driven epileptic seizure abatement.

    Directory of Open Access Journals (Sweden)

    Peter Neal Taylor

    Full Text Available Active brain stimulation to abate epileptic seizures has shown mixed success. In spike-wave (SW seizures, where the seizure and background state were proposed to coexist, single-pulse stimulations have been suggested to be able to terminate the seizure prematurely. However, several factors can impact success in such a bistable setting. The factors contributing to this have not been fully investigated on a theoretical and mechanistic basis. Our aim is to elucidate mechanisms that influence the success of single-pulse stimulation in noise-induced SW seizures. In this work, we study a neural population model of SW seizures that allows the reconstruction of the basin of attraction of the background activity as a four dimensional geometric object. For the deterministic (noise-free case, we show how the success of response to stimuli depends on the amplitude and phase of the SW cycle, in addition to the direction of the stimulus in state space. In the case of spontaneous noise-induced seizures, the basin becomes probabilistic introducing some degree of uncertainty to the stimulation outcome while maintaining qualitative features of the noise-free case. Additionally, due to the different time scales involved in SW generation, there is substantial variation between SW cycles, implying that there may not be a fixed set of optimal stimulation parameters for SW seizures. In contrast, the model suggests an adaptive approach to find optimal stimulation parameters patient-specifically, based on real-time estimation of the position in state space. We discuss how the modelling work can be exploited to rationally design a successful stimulation protocol for the abatement of SW seizures using real-time SW detection.

  17. Stimulus size dependence of information transfer from retina to thalamus

    Directory of Open Access Journals (Sweden)

    Robert Uglesich

    2009-10-01

    Full Text Available Relay cells in the mammalian lateral geniculate nucleus (LGN are driven primarily by single retinal ganglion cells (RGCs. However, an LGN cell responds typically to less than half of the spikes it receives from the RGC that drives it, and without retinal drive the LGN is silent (Kaplan and Shapley, 1984. Recent studies, which used stimuli restricted to the receptive field (RF center, show that despite the great loss of spikes, more than half of the information carried by the RGC discharge is typically preserved in the LGN discharge (Sincich et al., 2009, suggesting that the retinal spikes that are deleted by the LGN carry less information than those that are transmitted to the cortex. To determine how LGN relay neurons decide which retinal spikes to respond to, we recorded extracellularly from the cat LGN the LGN spikes together with the slow synaptic (‘S’ potentials that signal the firing of retinal spikes. We investigated the influence of the inhibitory surround of the LGN RF by stimulating the eyes with spots of various sizes, the largest of which covered the center and surround of the LGN relay cell’s RF. We found that for stimuli that activated mostly the RF center, each LGN spike delivered more information than the retinal spike, but this difference was reduced as stimulus size increased to cover the RF surround. To evaluate the optimality of the LGN editing of retinal spikes, we created artificial spike trains from the retinal ones by various deletion schemes. We found that single LGN cells transmitted less information than an optimal detector could.

  18. Visual search for emotional expressions: Effect of stimulus set on anger and happiness superiority.

    Science.gov (United States)

    Savage, Ruth A; Becker, Stefanie I; Lipp, Ottmar V

    2016-01-01

    Prior reports of preferential detection of emotional expressions in visual search have yielded inconsistent results, even for face stimuli that avoid obvious expression-related perceptual confounds. The current study investigated inconsistent reports of anger and happiness superiority effects using face stimuli drawn from the same database. Experiment 1 excluded procedural differences as a potential factor, replicating a happiness superiority effect in a procedure that previously yielded an anger superiority effect. Experiments 2a and 2b confirmed that image colour or poser gender did not account for prior inconsistent findings. Experiments 3a and 3b identified stimulus set as the critical variable, revealing happiness or anger superiority effects for two partially overlapping sets of face stimuli. The current results highlight the critical role of stimulus selection for the observation of happiness or anger superiority effects in visual search even for face stimuli that avoid obvious expression related perceptual confounds and are drawn from a single database.

  19. Non-Destructive Study of Bulk Crystallinity and Elemental Composition of Natural Gold Single Crystal Samples by Energy-Resolved Neutron Imaging

    Science.gov (United States)

    Tremsin, Anton S.; Rakovan, John; Shinohara, Takenao; Kockelmann, Winfried; Losko, Adrian S.; Vogel, Sven C.

    2017-01-01

    Energy-resolved neutron imaging enables non-destructive analyses of bulk structure and elemental composition, which can be resolved with high spatial resolution at bright pulsed spallation neutron sources due to recent developments and improvements of neutron counting detectors. This technique, suitable for many applications, is demonstrated here with a specific study of ~5–10 mm thick natural gold samples. Through the analysis of neutron absorption resonances the spatial distribution of palladium (with average elemental concentration of ~0.4 atom% and ~5 atom%) is mapped within the gold samples. At the same time, the analysis of coherent neutron scattering in the thermal and cold energy regimes reveals which samples have a single-crystalline bulk structure through the entire sample volume. A spatially resolved analysis is possible because neutron transmission spectra are measured simultaneously on each detector pixel in the epithermal, thermal and cold energy ranges. With a pixel size of 55 μm and a detector-area of 512 by 512 pixels, a total of 262,144 neutron transmission spectra are measured concurrently. The results of our experiments indicate that high resolution energy-resolved neutron imaging is a very attractive analytical technique in cases where other conventional non-destructive methods are ineffective due to sample opacity. PMID:28102285

  20. Stimulus-associated urinary urges in overactive bladder syndrome.

    Science.gov (United States)

    O'Connell, Kathleen A; Singer, Jonathan; Rajan, Sonali

    2018-01-01

    Although anecdotal reports of urinary urgency at one's front door are common in overactive bladder syndrome (OAB), little research has been done on how one's front door and other stimuli are related to urinary symptoms. We hypothesized that individuals with OAB would have higher scores on the Urinary Cues Questionnaire, developed for this study to assess stimulus-associated urinary urges, than those without OAB. Online surveys were administered to 328 women age 18-40 years recruited from a respondent panel maintained by CINT such that one-third of the sample reported a diagnosis of OAB. The survey assessed OAB symptoms and the frequency with which participants associated 42 stimuli with the urge to urinate. Psychometric analyses showed internal consistency estimates of the Urinary Cues Questionnaire of α = 0.97 and a test-retest correlation of 0.91. Women with OAB had significantly higher Urinary Cues Scores than those without OAB, with a t-test showing a large effect size of d = 1.49 (95%CI 1.24, 1.74), P < 0.001. Behavioral treatments aimed at reducing the response to cues may be useful in OAB, but more research is needed on both treatment implications and on the trajectory of symptom development. © 2017 Wiley Periodicals, Inc.

  1. Isolation and cloning of exendin precursor cDNAs from single samples of venom from the Mexican beaded lizard (Heloderma horridum) and the Gila monster (Heloderma suspectum).

    Science.gov (United States)

    Chen, Tianbao; Kwok, Hangfai; Ivanyi, Craig; Shaw, Chris

    2006-03-01

    Reptile venoms are complex cocktails of bioactive molecules, including peptides. While the drug discovery potential of most species remains unrealized, many are endangered and afforded protection under international treaties. In this study, we describe how potential clinically important bioactive peptides and their corresponding mRNAs can be structurally characterized from single, small samples of reptile venom. The potential type-2 diabetes therapeutics, exendin-3 and exendin-4, from the Mexican beaded lizard (Heloderma horridum) and the Gila monster (Heloderma suspectum), respectively, have been characterized at both protein and nucleic acid levels to illustrate the efficacy of the technique and its contribution to biodiversity conservation.

  2. Nanoscale theranostics for physical stimulus-responsive cancer therapies.

    Science.gov (United States)

    Chen, Qian; Ke, Hengte; Dai, Zhifei; Liu, Zhuang

    2015-12-01

    Physical stimulus-responsive therapies often employing multifunctional theranostic agents responsive to external physical stimuli such as light, magnetic field, ultra-sound, radiofrequency, X-ray, etc., have been widely explored as novel cancer therapy strategies, showing encouraging results in many pre-clinical animal experiments. Unlike conventional cancer chemotherapy which often accompanies with severe toxic side effects, physical stimulus-responsive agents usually are non-toxic by themselves and would destruct cancer cells only under specific external stimuli, and thus could offer greatly reduced toxicity and enhanced treatment specificity. In addition, physical stimulus-responsive therapies can also be combined with other traditional therapeutics to achieve synergistic anti-tumor effects via a variety of mechanisms. In this review, we will summarize the latest progress in the development of physical stimulus-responsive therapies, and discuss the important roles of nanoscale theranostic agents involved in those non-conventional therapeutic strategies. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. Signalization and stimulus-substitution in Pavlov's theory of conditioning.

    Science.gov (United States)

    García-Hoz, Víctor

    2003-11-01

    The concept of conditioning as signalization proposed by Ivan P. Pavlov (1927, 1928) is studied in relation to the theory of stimulus-substitution, which is also attributed to him. In the so-called theory of stimulus-substitution a distinction must be made between an empirical principle of substitution and an actual theory of substitution, which can adopt different forms. The Pavlovian theory of substitution--which conceives substitution as a substitution of the unconditioned stimulus (US) by the conditioned stimulus (CS) in the activation of the representation of the former--can be understood as an explanation or model of signalization. Signalization and substitution are answers to different questions, and the level of analysis to which signalization corresponds, is that which concerns the nature of conditioning as an operation of the animal in the environment.

  4. Automatic detection of frequency changes depends on auditory stimulus intensity.

    Science.gov (United States)

    Salo, S; Lang, A H; Aaltonen, O; Lertola, K; Kärki, T

    1999-06-01

    A cortical cognitive auditory evoked potential, mismatch negativity (MMN), reflects automatic discrimination and echoic memory functions of the auditory system. For this study, we examined whether this potential is dependent on the stimulus intensity. The MMN potentials were recorded from 10 subjects with normal hearing using a sine tone of 1000 Hz as the standard stimulus and a sine tone of 1141 Hz as the deviant stimulus, with probabilities of 90% and 10%, respectively. The intensities were 40, 50, 60, 70, and 80 dB HL for both standard and deviant stimuli in separate blocks. Stimulus intensity had a statistically significant effect on the mean amplitude, rise time parameter, and onset latency of the MMN. Automatic auditory discrimination seems to be dependent on the sound pressure level of the stimuli.

  5. Relative effectiveness of kinetic analysis vs single point readings for classifying environmental samples based on community-level physiological profiles (CLPP)

    Science.gov (United States)

    Garland, J. L.; Mills, A. L.; Young, J. S.

    2001-01-01

    The relative effectiveness of average-well-color-development-normalized single-point absorbance readings (AWCD) vs the kinetic parameters mu(m), lambda, A, and integral (AREA) of the modified Gompertz equation fit to the color development curve resulting from reduction of a redox sensitive dye from microbial respiration of 95 separate sole carbon sources in microplate wells was compared for a dilution series of rhizosphere samples from hydroponically grown wheat and potato ranging in inoculum densities of 1 x 10(4)-4 x 10(6) cells ml-1. Patterns generated with each parameter were analyzed using principal component analysis (PCA) and discriminant function analysis (DFA) to test relative resolving power. Samples of equivalent cell density (undiluted samples) were correctly classified by rhizosphere type for all parameters based on DFA analysis of the first five PC scores. Analysis of undiluted and 1:4 diluted samples resulted in misclassification of at least two of the wheat samples for all parameters except the AWCD normalized (0.50 abs. units) data, and analysis of undiluted, 1:4, and 1:16 diluted samples resulted in misclassification for all parameter types. Ordination of samples along the first principal component (PC) was correlated to inoculum density in analyses performed on all of the kinetic parameters, but no such influence was seen for AWCD-derived results. The carbon sources responsible for classification differed among the variable types with the exception of AREA and A, which were strongly correlated. These results indicate that the use of kinetic parameters for pattern analysis in CLPP may provide some additional information, but only if the influence of inoculum density is carefully considered. c2001 Elsevier Science Ltd. All rights reserved.

  6. A precise evaluation of glomerular filtration rate (GFR) in two plasma samples following a single administration of 57Co-B12 vitamin

    International Nuclear Information System (INIS)

    Camargo, E.E.; Rockmann, R.L.; Barreto, T.M.; Eston, T.E.; Papaleo Netto, M.; Carvalho, N.

    1974-01-01

    Through a logarithmic regression performed with the contings of 4 plasma samples withdrawn at 20,40,60 and 80 minutes after a venous injection of vitamin B 12 - 57 Co, the glomerular filtration-rate(GFR) in 11 patients, performing simultaneously the same study with EDTA- 51 Cr in 3 of them, is evaluated. The values obtained through the regression straight line are compared with those given by only 2 points, in the 6 possible combinations: 20 and 40 minutes, 20 and 60 minutes, 20 and 80 minutes, 40 and 60 minutes, 40 and 80 minutes, 60 and 80 minutes. The pair of points obtained at 20 and 80 minutes determined the straight line most similar to the logarithmic regression and as a simplification of the method, the withdraw of only 2 plasma samples, at and 80 minutes after a single injection of vitamin B 12 -57 Co is proposed [pt

  7. Reversed-phase single drop microextraction followed by high-performance liquid chromatography with fluorescence detection for the quantification of synthetic phenolic antioxidants in edible oil samples.

    Science.gov (United States)

    Farajmand, Bahman; Esteki, Mahnaz; Koohpour, Elham; Salmani, Vahid

    2017-04-01

    The reversed-phase mode of single drop microextraction has been used as a preparation method for the extraction of some phenolic antioxidants from edible oil samples. Butylated hydroxyl anisole, tert-butylhydroquinone and butylated hydroxytoluene were employed as target compounds for this study. High-performance liquid chromatography followed by fluorescence detection was applied for final determination of target compounds. The most interesting feature of this study is the application of a disposable insulin syringe with some modification for microextraction procedure that efficiently improved the volume and stability of the solvent microdrop. Different parameters such as the type and volume of solvent, sample stirring rate, extraction temperature, and time were investigated and optimized. Analytical performances of the method were evaluated under optimized conditions. Under the optimal conditions, relative standard deviations were between 4.4 and 10.2%. Linear dynamic ranges were 20-10 000 to 2-1000 μg/g (depending on the analytes). Detection limits were 5-670 ng/g. Finally, the proposed method was successfully used for quantification of the antioxidants in some edible oil samples prepared from market. Relative recoveries were achieved from 88 to 111%. The proposed method had a simplicity of operation, low cost, and successful application for real samples. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Relationship between single and multiple perpetrator rape perpetration in South Africa: A comparison of risk factors in a population-based sample.

    Science.gov (United States)

    R, Jewkes; Y, Sikweyiya; K, Dunkle; R, Morrell

    2015-07-07

    Studies of rape of women seldom distinguish between men's participation in acts of single and multiple perpetrator rape. Multiple perpetrator rape (MPR) occurs globally with serious consequences for women. In South Africa it is a cultural practice with defined circumstances in which it commonly occurs. Prevention requires an understanding of whether it is a context specific intensification of single perpetrator rape, or a distinctly different practice of different men. This paper aims to address this question. We conducted a cross-sectional household study with a multi-stage, randomly selected sample of 1686 men aged 18-49 who completed a questionnaire administered using an Audio-enhanced Personal Digital Assistant. We attempted to fit an ordered logistic regression model for factors associated with rape perpetration. 27.6 % of men had raped and 8.8 % had perpetrated multiple perpetrator rape (MPR). Thus 31.9 % of men who had ever raped had done so with other perpetrators. An ordered regression model was fitted, showing that the same associated factors, albeit at higher prevalence, are associated with SPR and MPR. Multiple perpetrator rape appears as an intensified form of single perpetrator rape, rather than a different form of rape. Prevention approaches need to be mainstreamed among young men.

  9. Current sharing temperature of NbTi SULTAN samples compared to prediction using a single pinning mechanism parametrization for NbTi strand

    International Nuclear Information System (INIS)

    Pong, Ian; Vostner, Alexander; Devred, Arnaud; Bessette, Denis; Mitchell, Neil; Bordini, Bernardo; Bottura, Luca; Jewell, Matthew; Long Feng; Wu Yu

    2012-01-01

    NbTi strands to be used in four of the six ITER poloidal field (PF) coils, all the correction coils (CC) and all the superconducting feeder busbars are being produced in China. Short full-size qualification conductor (cabled and jacketed) samples have been developed at ASIPP and tested at CRPP. Single pinning mechanism parametrization for this Chinese strand (type S2) has been obtained using the Bottura scaling law. The determination of the scaling parameters using a Kramer-type regression method will be described. A comparison between the critical temperature at the operating current and field of a single strand as determined by the parametrization and the current sharing temperature (T CS ) of a few conductor samples tested at the SULTAN facility will be made. The validity and limitation of the estimation will be discussed. The estimated T CS dependence on various (superconducting critical as well as geometric and volumetric) parameters will be assessed using the modelled critical surface. Errors propagated from critical current (I c ) measurements of the strands and parameter fitting, and other uncertainties, will be quantified. (paper)

  10. Replica exchange enveloping distribution sampling (RE-EDS): A robust method to estimate multiple free-energy differences from a single simulation.

    Science.gov (United States)

    Sidler, Dominik; Schwaninger, Arthur; Riniker, Sereina

    2016-10-21

    In molecular dynamics (MD) simulations, free-energy differences are often calculated using free energy perturbation or thermodynamic integration (TI) methods. However, both techniques are only suited to calculate free-energy differences between two end states. Enveloping distribution sampling (EDS) presents an attractive alternative that allows to calculate multiple free-energy differences in a single simulation. In EDS, a reference state is simulated which "envelopes" the end states. The challenge of this methodology is the determination of optimal reference-state parameters to ensure equal sampling of all end states. Currently, the automatic determination of the reference-state parameters for multiple end states is an unsolved issue that limits the application of the methodology. To resolve this, we have generalised the replica-exchange EDS (RE-EDS) approach, introduced by Lee et al. [J. Chem. Theory Comput. 10, 2738 (2014)] for constant-pH MD simulations. By exchanging configurations between replicas with different reference-state parameters, the complexity of the parameter-choice problem can be substantially reduced. A new robust scheme to estimate the reference-state parameters from a short initial RE-EDS simulation with default parameters was developed, which allowed the calculation of 36 free-energy differences between nine small-molecule inhibitors of phenylethanolamine N-methyltransferase from a single simulation. The resulting free-energy differences were in excellent agreement with values obtained previously by TI and two-state EDS simulations.

  11. Simultaneous determination of PPCPs, EDCs, and artificial sweeteners in environmental water samples using a single-step SPE coupled with HPLC-MS/MS and isotope dilution.

    Science.gov (United States)

    Tran, Ngoc Han; Hu, Jiangyong; Ong, Say Leong

    2013-09-15

    A high-throughput method for the simultaneous determination of 24 pharmaceuticals and personal care products (PPCPs), endocrine disrupting chemicals (EDCs) and artificial sweeteners (ASs) was developed. The method was based on a single-step solid phase extraction (SPE) coupled with high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) and isotope dilution. In this study, a single-step SPE procedure was optimized for simultaneous extraction of all target analytes. Good recoveries (≥ 70%) were observed for all target analytes when extraction was performed using Chromabond(®) HR-X (500 mg, 6 mL) cartridges under acidic condition (pH 2). HPLC-MS/MS parameters were optimized for the simultaneous analysis of 24 PPCPs, EDCs and ASs in a single injection. Quantification was performed by using 13 isotopically labeled internal standards (ILIS), which allows correcting efficiently the loss of the analytes during SPE procedure, matrix effects during HPLC-MS/MS and fluctuation in MS/MS signal intensity due to instrument. Method quantification limit (MQL) for most of the target analytes was below 10 ng/L in all water samples. The method was successfully applied for the simultaneous determination of PPCPs, EDCs and ASs in raw wastewater, surface water and groundwater samples collected in a local catchment area in Singapore. In conclusion, the developed method provided a valuable tool for investigating the occurrence, behavior, transport, and the fate of PPCPs, EDCs and ASs in the aquatic environment. Copyright © 2013 Elsevier B.V. All rights reserved.

  12. Discriminative stimulus properties of mitragynine (kratom) in rats.

    Science.gov (United States)

    Harun, Norsyifa; Hassan, Zurina; Navaratnam, Visweswaran; Mansor, Sharif M; Shoaib, Mohammed

    2015-07-01

    Mitragynine (MG) is the primary active alkaloid extracted from the leaves of Mitragyna speciosa or kratom and exhibits pharmacological activities mediated by opioid receptors. The plant has been traditionally used for its opium and psychostimulant-like effects to increase work efficiency or as a substitute in the self-treatment of opiate addiction. The present study was performed to investigate the discriminative stimulus effects of MG in rats. The pharmacological mechanism of MG action and its derivative, 7-hydroxymitragynine (7-HMG) with a specific focus on opioid receptor involvement was examined in rats trained to discriminate morphine from vehicle. In order to study the dual actions of MG, the effect of cocaine substitution to the MG discriminative stimulus was also performed in MG-trained rats. Male Sprague Dawley rats were trained to discriminate MG from vehicle in a two-lever drug discrimination procedure under a tandem variable-interval (VI 60') fixed-ratio (FR 10) schedule of food reinforcement. Rats acquired the MG discrimination (15.0 mg/kg, i.p.) which was similar to the acquisition of morphine discrimination (5.0 mg/kg, i.p.) in another group of rats. MG substituted fully to the morphine discriminative stimulus in a dose-dependent manner, suggesting pharmacological similarities between the two drugs. The administration of 7-HMG derivative in 3.0 mg/kg (i.p.) dose engendered full generalisation to the morphine discriminative stimulus. In addition, the MG stimulus also partially generalised to cocaine (10.0 mg/kg, i.p.) stimulus. The present study demonstrates that the discriminative stimulus effect of MG possesses both opioid- and psychostimulant-like subjective effects.

  13. Single-beam integrating sphere spectrophotometer for reflectance and transmittance measurements versus angle of incidence in the solar wavelength range on diffuse and specular samples

    Science.gov (United States)

    Nostell, Per; Roos, Arne; Rönnow, Daniel

    1999-05-01

    A multipurpose instrument for the measurement of reflectance and transmittance versus angle of incidence for both specular and diffuse samples in the solar wavelength range has been constructed and evaluated. The instrument operates in the single-beam mode and uses a common light source for three experimental setups. Two integrating spheres, 20 cm in diameter, are used for diffuse transmittance and reflectance measurements. The transmittance sphere can be turned around an axis through the sample to vary the angle of incidence. The reflectance sphere uses a center mounted sample and a special feature is the position of the detector, which is mounted on the sample holder at the center of the sphere. This way the detector always sees the same part of the sphere wall and no light can reach the detector directly from the sample. The third setup is an absolute instrument for specular samples. It uses a small averaging sphere as a detector. The detector is mounted on an arm which rotates around the center of the sample, and it can thus pick up both the reflected and transmitted beams including all multiply reflected components. The averaging sphere detector is insensitive to small side shifts of the detected beams and no multiple reflections between detector and optical system occur. In this report a number of calibration procedures are presented for the three experimental setups and models for the calculation of correct transmittance and reflectance values from measured data are presented. It is shown that for integrating sphere measurements, the geometry of the sphere and the diffusivity of the sample as well as the sphere wall reflectance and port losses are important factors that influence the result. For the center mounted configuration these factors are particularly important and special emphasis is given to the evaluation of the reflectance sphere model. All three instrument setups are calibrated using certified reference materials and nonscattering mirrors and

  14. Effects of Paradigm and Inter-Stimulus Interval on Age Differences in Eyeblink Classical Conditioning in Rabbits

    Science.gov (United States)

    Woodruff-Pak, Diana S.; Seta, Susan E.; Roker, LaToya A.; Lehr, Melissa A.

    2007-01-01

    The aim of this study was to examine parameters affecting age differences in eyeblink classical conditioning in a large sample of young and middle-aged rabbits. A total of 122 rabbits of mean ages of 4 or 26 mo were tested at inter-stimulus intervals (ISIs) of 600 or 750 msec in the delay or trace paradigms. Paradigm affected both age groups…

  15. Not so fast: Taste stimulus coding time in the rat revisited

    Directory of Open Access Journals (Sweden)

    Michael S. Weiss

    2012-05-01

    Full Text Available Behavioral and electrophysiological studies suggest that rats can identify a taste stimulus with a single lick, in <200 ms. Here, we tested the hypothesis that the number of licks of a tastant, its concentration and prior learning experience will modulate identification. In Experiment 1A, we trained rats to avoid licking a weak quinine solution (0.1 mM by pairing it with a LiCl injection in the home cage. Control groups either received no experience with quinine or received both quinine and a LiCl injection that were unpaired. Rats were later water deprived and tested in an experimental chamber. A computer-controlled drinking spout allowed delivery of 1, 2 or 3 consecutive licks of tastants, interspersed with 5 water rinse licks presented on a variable ratio schedule. Tastants were quinine (0.1 mM, Q; 10 mM, HQ, NaCl (100 mM, N, saccharin (4 mM, S and citric acid (10 mM, CA, dissolved in distilled water. Each rat was tested with Q, N, S, CA and water with 1, 2 or 3 stimulus licks on separate days. Rats showed evidence of Q avoidance/identification by the fourth interlick interval (ILI, ~580 ms, but only after aversion training and only in the 3-lick condition. To assess the effects of the motivation, we divided each session into halves. Only one trained rat identified Q after ILI-3, ~435 ms, in the second half of the session when given 3 licks of each stimulus. In Experiment 1B, we tested the same rats with HQ and found that all rats, regardless of learning condition, could identify quinine by ILI-4, ~580 ms. In Experiments 2 and 3, rats were given a choice of Q or HQ vs. S and Q or HQ vs. sucrose (100 mM in a 1-lick paradigm. Results showed that decreasing the number of choices of tastants in a session did not speed avoidance/identification of Q. Present data suggest that the neural representation of a taste stimulus may require only a single lick, but stimulus identification time may be a function of experience and motivation.

  16. Locomotion Induces Stimulus-Specific Response Enhancement in Adult Visual Cortex.

    Science.gov (United States)

    Kaneko, Megumi; Fu, Yu; Stryker, Michael P

    2017-03-29

    The responses of neurons in the visual cortex (V1) of adult mammals have long been thought to be stable over long periods. Here, we investigated whether repeated exposure to specific stimuli would enhance V1 visual responses in mice using intrinsic signal imaging through the intact skull and two-photon imaging of calcium signals in single neurons. Mice ran on Styrofoam balls floating on air while viewing one of three different, high-contrast visual stimuli. V1 responses to the stimuli that were viewed by the animal were specifically enhanced, while responses to other stimuli were unaffected. Similar exposure in stationary mice or in mice in which NMDA receptors were partially blocked did not significantly enhance responses. These findings indicate that stimulus-specific plasticity in the adult visual cortex depends on concurrent locomotion, presumably as a result of the high-gain state of the visual cortex induced by locomotion. SIGNIFICANCE STATEMENT We report a rapid and persistent increase in visual cortical responses to visual stimuli presented during locomotion in intact mice. We first used a method that is completely noninvasive to image intrinsic signals through the intact skull. We then measured the same effects on single neurons using two-photon calcium imaging and found that the increase in response to a particular stimulus produced by locomotion depends on how well the neuron is initially driven by the stimulus. To our knowledge, this is the first time such enhancement has been described in single neurons or using noninvasive measurements. Copyright © 2017 the authors 0270-6474/17/373532-12$15.00/0.

  17. High throughput and accurate serum proteome profiling by integrated sample preparation technology and single-run data independent mass spectrometry analysis.

    Science.gov (United States)

    Lin, Lin; Zheng, Jiaxin; Yu, Quan; Chen, Wendong; Xing, Jinchun; Chen, Chenxi; Tian, Ruijun

    2018-03-01

    Mass spectrometry (MS)-based serum proteome analysis is extremely challenging due to its high complexity and dynamic range of protein abundances. Developing high throughput and accurate serum proteomic profiling approach capable of analyzing large cohorts is urgently needed for biomarker discovery. Herein, we report a streamlined workflow for fast and accurate proteomic profiling from 1μL of blood serum. The workflow combined an integrated technique for highly sensitive and reproducible sample preparation and a new data-independent acquisition (DIA)-based MS method. Comparing with standard data dependent acquisition (DDA) approach, the optimized DIA method doubled the number of detected peptides and proteins with better reproducibility. Without protein immunodepletion and prefractionation, the single-run DIA analysis enables quantitative profiling of over 300 proteins with 50min gradient time. The quantified proteins span more than five orders of magnitude of abundance range and contain over 50 FDA-approved disease markers. The workflow allowed us to analyze 20 serum samples per day, with about 358 protein groups per sample being identified. A proof-of-concept study on renal cell carcinoma (RCC) serum samples confirmed the feasibility of the workflow for large scale serum proteomic profiling and disease-related biomarker discovery. Blood serum or plasma is the predominant specimen for clinical proteomic studies while the analysis is extremely challenging for its high complexity. Many efforts had been made in the past for serum proteomics for maximizing protein identifications, whereas few have been concerned with throughput and reproducibility. Here, we establish a rapid, robust and high reproducible DIA-based workflow for streamlined serum proteomic profiling from 1μL serum. The workflow doesn't need protein depletion and pre-fractionation, while still being able to detect disease-relevant proteins accurately. The workflow is promising in clinical application

  18. Thermal transfer and apparent-dose distributions in poorly bleached mortar samples: Results from single grains and small aliquots of quartz

    DEFF Research Database (Denmark)

    Jain, M.; Thomsen, Kristina Jørkov; Bøtter-Jensen, L.

    2004-01-01

    -300 mum and compare the dose-distributions obtained from small aliquots and single-grain procedures. A comparison of three different methods viz. (a) first 5%, (b) probability plot and (c) comparison of internal and external uncertainties, is made for equivalent dose estimation. The results have......;, this process releases all the prior trapped charge and simultaneously sensitises the quartz. Unfortunately unheated materials such as mortar and concrete are more common in industrial sites and particularly in nuclear installations. These materials are usually exposed to daylight during quarrying...... and construction, but in general this exposure is insufficient to completely empty (bleach) any geological trapped charge. This leads to a distribution of apparent doses in the sample at the time of construction with only some (if any) grains exposed to sufficient light to be considered well bleached for OSL...

  19. Ultra-Trace Determination of Copper and Silver in Environmental Samples by Using Ionic Liquid-Based Single Drop Microextraction-Electrothermal Atomic Absorption Spectrometry

    Directory of Open Access Journals (Sweden)

    J. Abolhasani

    2013-11-01

    Full Text Available A sensitive, selective and effective ionic liquid-based single drop microextraction technique wasdeveloped by using ionic liquid, 1-hexyl-3-methylimidazolium hexafluorophosphate, C6MIMPF6, coupledwith electrothermal atomic absorption spectrometry (ETAAS for the determination of copper and silver inenvironmental samples. Dithizone was used as chelating agent. Several factors that influence themicroextraction efficiency and ETAAS signal, such as pH, dithizone concentration, extraction time, amounts ofionic liquid, stirring rate, pyrolysis and atomization temperature were investigated and the microextractionconditions were established. In the optimum experimental conditions, the detection limits (3 s of the methodwere 4 and 8 ng L-1 and corresponding relative standard deviations (0.1 μg L-1, n = 6 were 4.2% and 4.8% forAg and Cu, respectively. The developed method was validated by analysis of a certified reference material andapplied to the determination of silver and copper.

  20. Capillary electrophoresis coupled to evaporative light scattering detection for direct determination of underivatized amino acids: application to tea samples using carboxyled single-walled carbon nanotubes for sample preparation.

    Science.gov (United States)

    Bouri, Mohamed; Salghi, Rachid; Zougagh, Mohammed; Ríos, Angel

    2013-09-01

    An improved and efficient method for the determination of underivatized amino acids based on the use of CE coupled to evaporative light scattering detector (ELSD), involving carbon nanotubes, was successfully developed. Carboxyled single-walled carbon nanotubes were used for the first time to perform the clean-up of the analyzed samples, which were afterwards analyzed by CE-ELSD. White tea samples were used to demonstrate the usefulness of the CE-ELSD coupled methodology. A suitable interface, based on a triple tube design sprayer, was developed and successfully used for coupling both instruments. Parameters affecting the separation and determination, including the elimination of interferences, were studied and properly optimized. Under the optimized conditions good resolution was achieved for the separation of seven amino acids. The precision of the method, expressed as RSD, was found within the 3.5-5.3% range. The LOD obtained for the proposed method were in the 1.2-2.1 pg range and the LOQ, were in the 2.0-11.5 pg range, with injection pressure of 5 KPa for 20 s (15.3 nL). This method is simple, rapid, and selective compared with other conventional techniques. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Fluorescent dye imaging of the volume sampled by single well forced-gradient tracer tests evaluated in a laboratory-scale aquifer physical model.

    Science.gov (United States)

    Barns, Gareth L; Wilson, Ryan D; Thornton, Steven F

    2012-02-01

    This study presents a new method to visualise forced-gradient tracer tests in 2-D using a laboratory-scale aquifer physical model. Experiments were designed to investigate the volume of aquifer sampled in vertical dipole flow tracer tests (DFTT) and push-pull tests (PPT), using a miniature monitoring well and straddle packer arrangement equipped with solute injection and recovery chambers. These tests have previously been used to estimate bulk aquifer hydraulic and transport properties for the evaluation of natural attenuation and other remediation approaches. Experiments were performed in a silica glass bead-filled box, using a fluorescent tracer (fluorescein) to deduce conservative solute transport paths. Digital images of fluorescein transport were captured under ultraviolet light and processed to analyse tracer plume geometry and obtain point-concentration breakthrough histories. Inorganic anion mixtures were also used to obtain conventional tracer breakthrough histories. Concentration data from the conservative tracer breakthrough curves was compared with the digital images and a well characterised numerical model. The results show that the peak tracer breakthrough response in dipole flow tracer tests samples a zone of aquifer close to the well screen, while the sampling volume of push-pull tests is limited by the length of the straddle packers used. The effective sampling volume of these single well forced-gradient tests in isotropic conditions can be estimated with simple equations. The experimental approach offers the opportunity to evaluate under controlled conditions the theoretical basis, design and performance of DFTTs and PPTs in porous media in relation to measured flow and transport properties. Copyright © 2011 Elsevier B.V. All rights reserved.

  2. Integration of GC-MSD and ER-Calux® assay into a single protocol for determining steroid estrogens in environmental samples.

    Science.gov (United States)

    Avberšek, Miha; Žegura, Bojana; Filipič, Metka; Heath, Ester

    2011-11-01

    There are many published studies that use either chemical or biological methods to investigate steroid estrogens in the aquatic environment, but rarer are those that combine both. In this study, gas chromatography with mass selective detection (GC-MSD) and the ER-Calux(®) estrogenicity assay were integrated into a single protocol for simultaneous determination of natural (estrone--E1, 17β-estradiol--E2, estriol--E3) and synthetic (17α-ethinylestradiol--EE2) steroid estrogens concentrations and the total estrogenic potential of environmental samples. For integration purposes, several solvents were investigated and the commonly used dimethyl sulphoxide (DMSO) in the ER-Calux(®) assay was replaced by ethyl acetate, which is more compatible with gas chromatography and enables the same sample to be analysed by both GC-MSD and the ER-Calux(®) assay. The integrated protocol was initially tested using a standard mixture of estrogens. The results for pure standards showed that the estrogenicity calculated on the basis of GC-MSD and the ER-Calux(®) assay exhibited good correlation (r(2)=0.96; α=0.94). The result remained the same when spiked waste water extracts were tested (r(2)=0.92, α=1.02). When applied to real waste water influent and effluent samples the results proved (r(2)=0.93; α=0.99) the applicability of the protocol. The main advantages of this newly developed protocol are simple sample handling for both methods, and reduced material consumption and labour. In addition, it can be applied as either a complete or sequential analysis where the ER-Calux(®) assay is used as a pre-screening method prior to the chemical analysis. Copyright © 2011 Elsevier B.V. All rights reserved.

  3. Fluorescent dye imaging of the volume sampled by single well forced-gradient tracer tests evaluated in a laboratory-scale aquifer physical model

    Science.gov (United States)

    Barns, Gareth L.; Wilson, Ryan D.; Thornton, Steven F.

    2012-02-01

    This study presents a new method to visualise forced-gradient tracer tests in 2-D using a laboratory-scale aquifer physical model. Experiments were designed to investigate the volume of aquifer sampled in vertical dipole flow tracer tests (DFTT) and push-pull tests (PPT), using a miniature monitoring well and straddle packer arrangement equipped with solute injection and recovery chambers. These tests have previously been used to estimate bulk aquifer hydraulic and transport properties for the evaluation of natural attenuation and other remediation approaches. Experiments were performed in a silica glass bead-filled box, using a fluorescent tracer (fluorescein) to deduce conservative solute transport paths. Digital images of fluorescein transport were captured under ultraviolet light and processed to analyse tracer plume geometry and obtain point-concentration breakthrough histories. Inorganic anion mixtures were also used to obtain conventional tracer breakthrough histories. Concentration data from the conservative tracer breakthrough curves was compared with the digital images and a well characterised numerical model. The results show that the peak tracer breakthrough response in dipole flow tracer tests samples a zone of aquifer close to the well screen, while the sampling volume of push-pull tests is limited by the length of the straddle packers used. The effective sampling volume of these single well forced-gradient tests in isotropic conditions can be estimated with simple equations. The experimental approach offers the opportunity to evaluate under controlled conditions the theoretical basis, design and performance of DFTTs and PPTs in porous media in relation to measured flow and transport properties. DFTT = Dipole Flow Tracer Test, PPT = Push Pull Tracer Test.

  4. Amostragem por larva-única na vigilância de Aedes aegypti Single-larva sampling for Aedes aegypti surveillance

    Directory of Open Access Journals (Sweden)

    José Eduardo Bracco

    1995-04-01

    Full Text Available Com a finalidade de testar a metodologia de amostragem por larva-única na vigilância entomológica do Aedes aegypti, foram pesquisados domicílios do Município de Araraquara, SP (Brasil. Nos criadouros que continham larvas de Aedes uma delas foi coletada. Como controle, após a coleta da larva-única, todas as larvas foram coletadas para identificação posterior. Esse processo foi repetido no laboratório. Dos 447 domicílios visitados, apenas 12 foram considerados positivos e 20 criadouros foram identificados; destes, 13 continham larvas de Aedes; 5, larvas de Aedes e Culex e 2, larvas de Culex. Os resultados mostram o reconhecimento correto, no campo, de todos os criadouros, evidenciando que o método poderia ser utilizado na vigilância entomológica de municípios sem infestação domiciliar ou infestados apenas com uma única espécie de Aedes.Buildings in Araraquara city, Southeastern Brazil, were searched during a year for the presence of Aedes larvae using single larva sampling in order to check the single-larva methodology. In those breeding places in wich Aedes larvae were found, one of them was collected. As a control, after the single larva had been collected, all the larvae from the breeding place were collected for later identification. This process was repeated in the laboratory. Of the 447 domiciles searched, 12 were considered positive and 20 breeding places were found. Of the breeding places, 13 contained Aedes larvae, 5 both Aedes and Culex larvae and 2 Culex larvae only. The results show that all the breeding places in the field were properly recognited showing the method may be used for Aedes surveillance in cities infested with one species only or without any domiciliary infestation.

  5. The structural and magnetic properties of CsxFe2-ySe2 as determined by x ray and neutron scattering of powder and single crystal samples

    Science.gov (United States)

    Taddei, Keith; Chmaissem, Omar; Sturza, Mihai; Avci, Sevda; Claus, Helmut; Kanatzids, Mercouri; Rosenkranz, Stephan; Osborn, Ray

    2014-03-01

    The AxFe2-ySe2 family of iron selenides (A = K, Rb and Cs) has proven an intricate system for the study of unconventional superconductivity, exhibiting high temperature superconductivity (~ 30 K) and a complex structural phase transition into a biphasic state coupled with a high temperature magnetic transition (~ 500 K). While isostructural to the 122 arsenides, significant structural differences are identified. In the selenides, iron vacancies in the tetrahedral FeSe layers become ordered below a high temperature structural transition defining a main phase √ 5 × √ 5 superstructure. Coexistent with the main phase, a secondary phase of a previously contested structure is observed and it is in this biphasic state that superconductivity arises at ~ 30 K. Both powder and single crystal samples show similar phase separation and coexistence. In this talk, I will discuss structural results and lattice parameter evolution obtained from neutron powder diffraction as well as single crystal x-ray diffraction with an emphasis on a novel magnetic structural model, the identification of the secondary phase, and the nature of coincidence of the magnetic, structural and secondary phase transitions.

  6. Study on stimulus-responsive cellulose-based polymeric materials

    Science.gov (United States)

    Luo, Hongsheng

    Stimulus-responsive cellulose-based polymeric materials were developed by physical and chemical approaches. The thermal, structural, mechanical and morphological properties of the samples were comprehensively investigated by multiple tools. Shape memory effect (SME), programming-structure-property relationship and underling mechanisms were emphasized in this study. Some new concepts, such as heterogeneous-twin-switch, path-dependent multi-shape, rapidly switchable water-sensitive SME were established. The samples were divided into two categories. For the first category, cellulose nano-whiskers (CNWs) were incorporated into crystalline shape memory polyurethane (SMPU) and thermal plastic polyurethane (TPU). The CNW-SMPU nano-composites had heterogeneous switches. Triple- and multi-shape effects were achieved for the CNW-SMPU nano-composites by applying into appropriate thermal-aqueous-mechanical programming. Furthermore, the thermally triggered shape recovery of the composites was found to be tuneable, depending on the PCN content. Theoretical prediction along with numerical analysis was conducted, providing evidence on the possible microstructure of the CNW-SMPU nano-composites. Rapidly switchable water-sensitive SME of the CNW-TPU nano-composites was unprecedentedly studied, which originated from the reversible regulation of hydrogen bonding by water. The samples in the second category consisted of cellulose-polyurethane (PU) blends, cellulose-poly(acrylic acid) (PAA) composites and modified cellulose with supramolecular switches, featuring the requirement of homogeneous cellulose solution in the synthesis process. The reversible behaviours of the cellulose-PU blends in wet-dry cycles as well as the underlying shape memory mechanism were characterized and disclosed. The micro-patterns of the blends were found to be self-similar in fractal dimensions. Cellulose-PAA semi-interpenetrating networks exhibited mechanical adaptability in wet-dry cycles. A type of

  7. Cognitive versus stimulus-response theories of learning.

    Science.gov (United States)

    Holland, Peter C

    2008-08-01

    In his 1948 address to the Division of Theoretical-Experimental Psychology of the American Psychological Association, Kenneth W. Spence discussed six distinctions between cognitive and stimulus-response (S-R) theories of learning. In this article, I first review these six distinctions and then focus on two of them in the context of my own research. This research concerns the specification of stimulus-stimulus associations in associative learning and the characterization of the neural systems underlying those associations. In the course of describing Spence's views and my research, I hope to communicate some of the richness of Spence's S-R psychology and its currency within modern scientific analyses of behavior.

  8. Stimulus characteristics in electroconvulsive therapy. A pragmatic review.

    Science.gov (United States)

    Sanz-Fuentenebro, Francisco Javier

    The process of normalization electroconvulsive therapy (ECT) requires, among other actions, disseminating the latest information on this technique. One of the most complex aspects is the electrical stimulus, whose knowledge should be spread and put into practice. In this paper we review the available information about frequency and number of ECT sessions, and efficacy of each electrode placement. We also present two approaches to determine the ECT charge: stimulus titration versus age-based method; and the limitations of the summary metrics of charge, being necessary to expand our knowledge of the parameters that configure the stimulus: duration, current amplitude frequency and pulse width. Copyright © 2016 SEP y SEPB. Publicado por Elsevier España, S.L.U. All rights reserved.

  9. Stimulus-dependent effects on tactile spatial acuity

    Directory of Open Access Journals (Sweden)

    Tommerdahl M

    2005-10-01

    Full Text Available Abstract Background Previous studies have shown that spatio-tactile acuity is influenced by the clarity of the cortical response in primary somatosensory cortex (SI. Stimulus characteristics such as frequency, amplitude, and location of tactile stimuli presented to the skin have been shown to have a significant effect on the response in SI. The present study observes the effect of changing stimulus parameters of 25 Hz sinusoidal vertical skin displacement stimulation ("flutter" on a human subject's ability to discriminate between two adjacent or near-adjacent skin sites. Based on results obtained from recent neurophysiological studies of the SI response to different conditions of vibrotactile stimulation, we predicted that the addition of 200 Hz vibration to the same site that a two-point flutter stimulus was delivered on the skin would improve a subject's spatio-tactile acuity over that measured with flutter alone. Additionally, similar neurophysiological studies predict that the presence of either a 25 Hz flutter or 200 Hz vibration stimulus on the unattended hand (on the opposite side of the body from the site of two-point limen testing – the condition of bilateral stimulation – which has been shown to evoke less SI cortical activity than the contralateral-only stimulus condition would decrease a subject's ability to discriminate between two points on the skin. Results A Bekesy tracking method was employed to track a subject's ability to discriminate between two-point stimuli delivered to the skin. The distance between the two points of stimulation was varied on a trial-by-trial basis, and several different stimulus conditions were examined: (1 The "control" condition, in which 25 Hz flutter stimuli were delivered simultaneously to the two points on the skin of the attended hand, (2 the "complex" condition, in which a combination of 25 Hz flutter and 200 Hz vibration stimuli were delivered to the two points on the attended hand, and (3 a

  10. Significance of a notch in the otoacoustic emission stimulus spectrum.

    Science.gov (United States)

    Grenner, J

    2012-09-01

    To explain a clinical observation: a notch in the stimulus spectrum during transient evoked otoacoustic emission measurement in ears with secretory otitis media. The effects of tympanic under-pressure were investigated using a pressure chamber. A model of the ear canal was also studied. Tympanic membrane reflectance increased as a consequence of increased stiffness, causing a notch in the stimulus spectrum. In an adult, the notch could be clearly distinguished at an under-pressure of approximately -185 daPa. The sound frequency of the notch corresponded to a wavelength four times the ear canal length. The ear canal of infants was too short to cause a notch within the displayed frequency range. The notch was demonstrated using both Otodynamics and Madsen equipment. A notch in the otoacoustic emission stimulus spectrum can be caused by increased stiffness of the tympanic membrane, raising suspicion of low middle-ear pressure or secretory otitis media. This finding is not applicable to infants.

  11. Cognitive control in bilinguals: Advantages in Stimulus–Stimulus inhibition*

    Science.gov (United States)

    BLUMENFELD, HENRIKE K.; MARIAN, VIORICA

    2014-01-01

    Bilinguals have been shown to outperform monolinguals at suppressing task-irrelevant information and on overall speed during cognitive control tasks. Here, monolinguals’ and bilinguals’ performance was compared on two nonlinguistic tasks: a Stroop task (with perceptual Stimulus–Stimulus conflict among stimulus features) and a Simon task (with Stimulus–Response conflict). Across two experiments testing bilinguals with different language profiles, bilinguals showed more efficient Stroop than Simon performance, relative to monolinguals, who showed fewer differences across the two tasks. Findings suggest that bilingualism may engage Stroop-type cognitive control mechanisms more than Simon-type mechanisms, likely due to increased Stimulus–Stimulus conflict during bilingual language processing. Findings are discussed in light of previous research on bilingual Stroop and Simon performance. PMID:25093009

  12. Reinforcing and discriminative stimulus properties of music in goldfish.

    Science.gov (United States)

    Shinozuka, Kazutaka; Ono, Haruka; Watanabe, Shigeru

    2013-10-01

    This paper investigated whether music has reinforcing and discriminative stimulus properties in goldfish. Experiment 1 examined the discriminative stimulus properties of music. The subjects were successfully trained to discriminate between two pieces of music--Toccata and Fugue in D minor (BWV 565) by J. S. Bach and The Rite of Spring by I. Stravinsky. Experiment 2 examined the reinforcing properties of sounds, including BWV 565 and The Rite of Spring. We developed an apparatus for measuring spontaneous sound preference in goldfish. Music or noise stimuli were presented depending on the subject's position in the aquarium, and the time spent in each area was measured. The results indicated that the goldfish did not show consistent preferences for music, although they showed significant avoidance of noise stimuli. These results suggest that music has discriminative but not reinforcing stimulus properties in goldfish. Copyright © 2013 Elsevier B.V. All rights reserved.

  13. Different mechanisms are responsible for dishabituation of electrophysiological auditory responses to a change in acoustic identity than to a change in stimulus location.

    Science.gov (United States)

    Smulders, Tom V; Jarvis, Erich D

    2013-11-01

    Repeated exposure to an auditory stimulus leads to habituation of the electrophysiological and immediate-early-gene (IEG) expression response in the auditory system. A novel auditory stimulus reinstates this response in a form of dishabituation. This has been interpreted as the start of new memory formation for this novel stimulus. Changes in the location of an otherwise identical auditory stimulus can also dishabituate the IEG expression response. This has been interpreted as an integration of stimulus identity and stimulus location into a single auditory object, encoded in the firing patterns of the auditory system. In this study, we further tested this hypothesis. Using chronic multi-electrode arrays to record multi-unit activity from the auditory system of awake and behaving zebra finches, we found that habituation occurs to repeated exposure to the same song and dishabituation with a novel song, similar to that described in head-fixed, restrained animals. A large proportion of recording sites also showed dishabituation when the same auditory stimulus was moved to a novel location. However, when the song was randomly moved among 8 interleaved locations, habituation occurred independently of the continuous changes in location. In contrast, when 8 different auditory stimuli were interleaved all from the same location, a separate habituation occurred to each stimulus. This result suggests that neuronal memories of the acoustic identity and spatial location are different, and that allocentric location of a stimulus is not encoded as part of the memory for an auditory object, while its acoustic properties are. We speculate that, instead, the dishabituation that occurs with a change from a stable location of a sound is due to the unexpectedness of the location change, and might be due to different underlying mechanisms than the dishabituation and separate habituations to different acoustic stimuli. Copyright © 2013 Elsevier Inc. All rights reserved.

  14. Determination of {sup 236}U in environmental samples by single extraction chromatography coupled to triple-quadrupole inductively coupled plasma-mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Guosheng [Department of Radiation Chemistry, Institute of Radiation Emergency Medicine, Hirosaki University, 66-1 Hon-cho, Hirosaki, Aomori, 036-8564 (Japan); Division of Nuclear Technology and Applications, Institute of High Energy Physics, Chinese Academy of Sciences (China); Beijing Engineering Research Center of Radiographic Techniques and Equipment, Beijing, 100049 (China); Tazoe, Hirofumi [Department of Radiation Chemistry, Institute of Radiation Emergency Medicine, Hirosaki University, 66-1 Hon-cho, Hirosaki, Aomori, 036-8564 (Japan); Yamada, Masatoshi, E-mail: myamada@hirosaki-u.ac.jp [Department of Radiation Chemistry, Institute of Radiation Emergency Medicine, Hirosaki University, 66-1 Hon-cho, Hirosaki, Aomori, 036-8564 (Japan)

    2016-11-09

    In order to measure trace {sup 236}U and {sup 236}U/{sup 238}U in environmental samples with a high matrix effect, a novel and simple method was developed that makes the digestion and purification procedures compatible with advanced triple-quadrupole inductively coupled plasma-mass spectrometry. A total dissolution of sample with HF + HNO{sub 3} + HClO{sub 4} was followed by chromatographic separation with a single resin column containing normal type DGA resin (N,N,N′,N’-tetra-n-octyldiglycolamide) as the extractant system. The analytical accuracy and precision of {sup 236}U/{sup 238}U ratios, measured as {sup 236}U{sup 16}O{sup +}/{sup 238}U{sup 16}O{sup +}, were examined by using the reference materials IAEA-135, IAEA-385, IAEA-447, and JSAC 0471. The low method detection limit (3.50 × 10{sup −6} Bq kg{sup −1}) makes it possible to perform routine monitoring of environmental {sup 236}U due to global fallout combined with the Fukushima Daiichi Nuclear Power Plant accident fallout (>10{sup −5} Bq kg{sup −1}). Finally, the developed method was successfully applied to measure {sup 236}U/{sup 238}U ratios and {sup 236}U activities in soil samples contaminated by the accident. The low {sup 236}U/{sup 238}U atom ratios ((1.50–13.5) × 10{sup −8}) and {sup 236}U activities ((2.25–14.1) × 10{sup −2} mBq kg{sup −1}) indicate {sup 236}U contamination was mainly derived from global fallout in the examined samples. - Highlights: • A simple {sup 236}U/{sup 238}U analytical method has been developed. • The separation required just one DGA column chromatography. • {sup 236}U/{sup 238}U atom ratios in soil were measured by ICP-MS/MS. • {sup 236}U/{sup 238}U atom ratios of (1.50–13.5) × 10{sup −8} were observed in Japanese samples. • {sup 236}U activities of (2.25–14.1) × 10{sup −2} mBq kg{sup −1} were found in Japanese samples.

  15. Photothermal desorption of single-walled carbon nanotubes and coconut shell-activated carbons using a continuous light source for application in air sampling.

    Science.gov (United States)

    Floyd, Evan L; Sapag, Karim; Oh, Jonghwa; Lungu, Claudiu T

    2014-08-01

    Many techniques exist to measure airborne volatile organic compounds (VOCs), each with differing advantages; sorbent sampling is compact, versatile, has good sample stability, and is the preferred technique for collecting VOCs for hygienists. Development of a desorption technique that allows multiple analyses per sample (similar to chemical desorption) with enhanced sensitivity (similar to thermal desorption) would be helpful to field hygienists. In this study, activated carbon (AC) and single-walled carbon nanotubes (SWNT) were preloaded with toluene vapor and partially desorbed with light using a common 12-V DC, 50-W incandescent/halogen lamp. A series of experimental chamber configurations were explored starting with a 500-ml chamber under static conditions, then with low ventilation and high ventilation, finally a 75-ml high ventilation chamber was evaluated. When preloaded with toluene and irradiated at the highest lamp setting for 4min, AC desorbed 13.9, 18.5, 23.8, and 45.9% of the loaded VOC mass, in each chamber configuration, respectively; SWNT desorbed 25.2, 24.3, 37.4, and 70.5% of the loaded VOC mass, respectively. SWNT desorption was significantly greater than AC in all test conditions (P = 0.02-<0.0001) demonstrating a substantial difference in sorbent performance. When loaded with 0.435mg toluene and desorbed at the highest lamp setting for 4min in the final chamber design, the mean desorption for AC was 45.8% (39.7, 52.0) and SWNT was 72.6% (68.8, 76.4) (mean represented in terms of 95% confidence interval). All desorption measurements were obtained using a field grade photoionization detector; this demonstrates the potential of using this technique to perform infield prescreening of VOC samples for immediate exposure feedback and in the analytical lab to introduce sample to a gas chromatograph for detailed analysis of the sample. © The Author 2014. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

  16. Effects of Multimodal Presentation and Stimulus Familiarity on Auditory and Visual Processing

    Science.gov (United States)

    Robinson, Christopher W.; Sloutsky, Vladimir M.

    2010-01-01

    Two experiments examined the effects of multimodal presentation and stimulus familiarity on auditory and visual processing. In Experiment 1, 10-month-olds were habituated to either an auditory stimulus, a visual stimulus, or an auditory-visual multimodal stimulus. Processing time was assessed during the habituation phase, and discrimination of…

  17. Is conscious stimulus identification dependent on knowledge of the perceptual modality? Testing the "source misidentification hypothesis"

    DEFF Research Database (Denmark)

    Overgaard, Morten; Lindeløv, Jonas Kristoffer; Svejstrup, Stinna

    2013-01-01

    to this knowledge (whether the stimulus was visual, auditory, or something else). We test this hypothesis in healthy subjects, asking them to report whether a masked stimulus was presented auditorily or visually, what the stimulus was, and how clearly they experienced the stimulus using the Perceptual Awareness...

  18. StimDuino: an Arduino-based electrophysiological stimulus isolator.

    Science.gov (United States)

    Sheinin, Anton; Lavi, Ayal; Michaelevski, Izhak

    2015-03-30

    Electrical stimulus isolator is a widely used device in electrophysiology. The timing of the stimulus application is usually automated and controlled by the external device or acquisition software; however, the intensity of the stimulus is adjusted manually. Inaccuracy, lack of reproducibility and no automation of the experimental protocol are disadvantages of the manual adjustment. To overcome these shortcomings, we developed StimDuino, an inexpensive Arduino-controlled stimulus isolator allowing highly accurate, reproducible automated setting of the stimulation current. The intensity of the stimulation current delivered by StimDuino is controlled by Arduino, an open-source microcontroller development platform. The automatic stimulation patterns are software-controlled and the parameters are set from Matlab-coded simple, intuitive and user-friendly graphical user interface. The software also allows remote control of the device over the network. Electrical current measurements showed that StimDuino produces the requested current output with high accuracy. In both hippocampal slice and in vivo recordings, the fEPSP measurements obtained with StimDuino and the commercial stimulus isolators showed high correlation. Commercial stimulus isolators are manually managed, while StimDuino generates automatic stimulation patterns with increasing current intensity. The pattern is utilized for the input-output relationship analysis, necessary for assessment of excitability. In contrast to StimuDuino, not all commercial devices are capable for remote control of the parameters and stimulation process. StimDuino-generated automation of the input-output relationship assessment eliminates need for the current intensity manually adjusting, improves stimulation reproducibility, accuracy and allows on-site and remote control of the stimulation parameters. Copyright © 2015 Elsevier B.V. All rights reserved.

  19. Stimulus-specific variability in color working memory with delayed estimation.

    Science.gov (United States)

    Bae, Gi-Yeul; Olkkonen, Maria; Allred, Sarah R; Wilson, Colin; Flombaum, Jonathan I

    2014-04-08

    Working memory for color has been the central focus in an ongoing debate concerning the structure and limits of visual working memory. Within this area, the delayed estimation task has played a key role. An implicit assumption in color working memory research generally, and delayed estimation in particular, is that the fidelity of memory does not depend on color value (and, relatedly, that experimental colors have been sampled homogeneously with respect to discriminability). This assumption is reflected in the common practice of collapsing across trials with different target colors when estimating memory precision and other model parameters. Here we investigated whether or not this assumption is secure. To do so, we conducted delayed estimation experiments following standard practice with a memory load of one. We discovered that different target colors evoked response distributions that differed widely in dispersion and that these stimulus-specific response properties were correlated across observers. Subsequent experiments demonstrated that stimulus-specific responses persist under higher memory loads and that at least part of the specificity arises in perception and is eventually propagated to working memory. Posthoc stimulus measurement revealed that rendered stimuli differed from nominal stimuli in both chromaticity and luminance. We discuss the implications of these deviations for both our results and those from other working memory studies.

  20. Simple 3-D stimulus for motion parallax and its simulation.

    Science.gov (United States)

    Ono, Hiroshi; Chornenkyy, Yevgen; D'Amour, Sarah

    2013-01-01

    Simulation of a given stimulus situation should produce the same perception as the original. Rogers et al (2009 Perception 38 907-911) simulated Wheeler's (1982, PhD thesis, Rutgers University, NJ) motion parallax stimulus and obtained quite different perceptions. Wheeler's observers were unable to reliably report the correct direction of depth, whereas Rogers's were. With three experiments we explored the possible reasons for the discrepancy. Our results suggest that Rogers was able to see depth from the simulation partly due to his experience seeing depth with random dot surfaces.

  1. A Comparative Study of Single-pulse and Double-pulse Laser-Induced Breakdown Spectroscopy with Uranium-containing Samples.

    Science.gov (United States)

    Skrodzki, Patrick J; Becker, Jason R; Diwakar, Prasoon K; Harilal, Sivanandan S; Hassanein, Ahmed

    2016-03-01

    Laser-induced breakdown spectroscopy (LIBS) holds potential advantages in special nuclear material (SNM) sensing and nuclear forensics, which require rapid analysis, minimal sample preparation, and stand-off distance capability. SNM, such as U, however, result in crowded emission spectra with LIBS, and characteristic emission lines are challenging to discern. It is well-known that double-pulse LIBS (DPLIBS) improves the signal intensity for analytes over conventional single-pulse LIBS (SPLIBS). This study investigates the U signal in a glass matrix using DPLIBS and compares it to signal obtained using SPLIBS. Double-pulse LIBS involves sequential firing of a 1.06 µm Nd:YAG pre-pulse and 10.6 µm TEA CO2 heating pulse in a near collinear geometry. Optimization of experimental parameters including inter-pulse delay and energy follows identification of characteristic lines for the bulk analyte Ca and the minor constituent analyte U for both DPLIBS and SPLIBS. Spatial and temporal coupling of the two pulses in the proposed DPLIBS technique yields improvements in analytical merits with a negligible increase in damage to the sample compared to SPLIBS. Subsequently, the study discusses optimum plasma emission conditions of U lines and relative figures of merit in both SPLIBS and DPLIBS. Investigation into plasma characteristics also addresses plausible mechanisms related to the observed U analyte signal variation between SPLIBS and DPLIBS. © The Author(s) 2016.

  2. Stimulus selectivity of drug purchase tasks: A preliminary study evaluating alcohol and cigarette demand.

    Science.gov (United States)

    Strickland, Justin C; Stoops, William W

    2017-06-01

    The use of drug purchase tasks to measure drug demand in human behavioral pharmacology and addiction research has proliferated in recent years. Few studies have systematically evaluated the stimulus selectivity of drug purchase tasks to demonstrate that demand metrics are specific to valuation of or demand for the commodity under study. Stimulus selectivity is broadly defined for this purpose as a condition under which a specific stimulus input or target (e.g., alcohol, cigarettes) is the primary determinant of behavior (e.g., demand). The overall goal of the present study was to evaluate the stimulus selectivity of drug purchase tasks. Participants were sampled from the Amazon.com's crowdsourcing platform Mechanical Turk. Participants completed either alcohol and soda purchase tasks (Experiment 1; N = 139) or cigarette and chocolate purchase tasks (Experiment 2; N = 46), and demand metrics were compared to self-reported use behaviors. Demand metrics for alcohol and soda were closely associated with commodity-similar (e.g., alcohol demand and weekly alcohol use) but not commodity-different (e.g., alcohol demand and weekly soda use) variables. A similar pattern was observed for cigarette and chocolate demand, but selectivity was not as consistent as for alcohol and soda. Collectively, we observed robust selectivity for alcohol and soda purchase tasks and modest selectivity for cigarette and chocolate purchase tasks. These preliminary outcomes suggest that demand metrics adequately reflect the specific commodity under study and support the continued use of purchase tasks in substance use research. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  3. Discriminative learning of receptive fields from responses to non-Gaussian stimulus ensembles.

    Directory of Open Access Journals (Sweden)

    Arne F Meyer

    Full Text Available Analysis of sensory neurons' processing characteristics requires simultaneous measurement of presented stimuli and concurrent spike responses. The functional transformation from high-dimensional stimulus space to the binary space of spike and non-spike responses is commonly described with linear-nonlinear models, whose linear filter component describes the neuron's receptive field. From a machine learning perspective, this corresponds to the binary classification problem of discriminating spike-eliciting from non-spike-eliciting stimulus examples. The classification-based receptive field (CbRF estimation method proposed here adapts a linear large-margin classifier to optimally predict experimental stimulus-response data and subsequently interprets learned classifier weights as the neuron's receptive field filter. Computational learning theory provides a theoretical framework for learning from data and guarantees optimality in the sense that the risk of erroneously assigning a spike-eliciting stimulus example to the non-spike class (and vice versa is minimized. Efficacy of the CbRF method is validated with simulations and for auditory spectro-temporal receptive field (STRF estimation from experimental recordings in the auditory midbrain of Mongolian gerbils. Acoustic stimulation is performed with frequency-modulated tone complexes that mimic properties of natural stimuli, specifically non-Gaussian amplitude distribution and higher-order correlations. Results demonstrate that the proposed approach successfully identifies correct underlying STRFs, even in cases where second-order methods based on the spike-triggered average (STA do not. Applied to small data samples, the method is shown to converge on smaller amounts of experimental recordings and with lower estimation variance than the generalized linear model and recent information theoretic methods. Thus, CbRF estimation may prove useful for investigation of neuronal processes in response to

  4. Environmental Stress Testing of the Single Sample Cylinder: A Proven Consensus Standard for Internal Gas Analysis (IGA) or Residual Gas Analysis (RGA)

    Science.gov (United States)

    Schuessler, Philipp WH

    2010-01-01

    In August 2008, Schuessler Consulting was contracted by NASA GSFC in support of the NASA Electronic Parts and Packaging (NEPP) program to perform two separate studies on moisture laden air in a stainless steel cylinder that had been designed to become a consensus standard for Test Method 1018. This Test Method was originally released for hybrids under Mil. Std. 883 but was quickly utilized on other microelectronic devices under the auspice of Mil. Std. 750. The cylinder had subsequently been fabricated for the 750 community. It was back-filled with moist air and subsequently analyzed over a period of time under a previous NASA contract. It had been shown that moisture in the 4000 - 5000 ppm range could be analyzed rather precisely with a mass spectrometer, commonly referred to as a Residual Gas Analyzer (RGA). The scope of this study was to ascertain if the composition and precision varied as a function of thermal shock at sub-zero temperatures and whether there was consensus when the standard was submitted to other RGA units. It was demonstrated and published that the consensus standard would yield precise RGA data for moisture within +/- 1% when optimized for a given RGA unit. It has been subsequently shown in this study at Oneida Research Services, that sub-zero storage did not affect that precision when a well-defined protocol for the analysis was followed. The consensus standard was taken to a second facility for analysis where it was found that moisture adsorption on the transfer lines caused precision to drop to +/- 12%. The Single Sample Cylinder (SSC) is a one liter stainless steel cylinder with associated sampling valves and has considerable weight and volume. But this considerable size allows for approximately 300 gas samples of the same composition to be delivered to any RGA unit. Lastly, a smaller cylinder, approximately 75 cc, of a second consensus standard was fabricated and tested with a different mix of fixed gases where moisture was kept in the

  5. Estimating the effective number of breeders from single parr samples for conservation monitoring of wild populations of Atlantic salmon Salmo salar.

    Science.gov (United States)

    Bacles, C F E; Bouchard, C; Lange, F; Manicki, A; Tentelier, C; Lepais, O

    2018-03-01

    This study assesses whether the effective number of breeders (N b ) can be estimated using a time and cost-effective protocol using genetic sibship reconstruction from a single sample of young-of-the-year (YOY) for the purposes of Atlantic salmon Salmo salar population monitoring. N b was estimated for 10 consecutive reproductive seasons for S. salar in the River Nivelle, a small population located at the rear-edge of the species distribution area in France, chronically under its conservation limit and subjected to anthropogenic and environmental changes. Subsampling of real and simulated data showed that accurate estimates of N b can be obtained from YOY genotypes, collected at moderate random sampling intensity, achievable using routine juvenile electrofishing protocols. Spatial bias and time elapsed since spawning were found to affect estimates, which must be accounted for in sampling designs. N b estimated in autumn for S. salar in the River Nivelle was low and variable across years from 23 (95% C.I. 14-41) to 75 (53-101) and was not statistically correlated with the estimated number of returning adults, but it was positively correlated with the estimated number of YOY at age 9 months. N b was found to be lower for intermediate levels of redd aggregation, suggesting that the strength of the competition between males to access females affects reproductive success variance depending on redd spatial configuration. Thus, environmental factors such as habitat availability and quality for spawning and YOY development predominate over demographic ones (number of returning adults) in driving long-term population viability for S. salar in the River Nivelle. This study showcases N b as an integrated parameter, encompassing demographic and ecological information about a reproductive event, relevant to the assessment of both short-term effects of management practices and long-term population conservation status. © 2018 The Fisheries Society of the British Isles.

  6. Spectroelectrochemical Sensing Based on Multimode Selectivity simultaneously Achievable in a Single Device. 11. Design and Evaluation of a Small Portable Sensor for the Determination of Ferrocyanide in Hanford Waste Samples

    International Nuclear Information System (INIS)

    Stegemiller, Michael L.; Heineman, William R.; Seliskar, Carl J.; Ridgway, Thomas H.; Bryan, Samuel A.; Hubler, Timothy L.; Sell, Richard L.

    2003-01-01

    Spectroelectrochemical sensing based on multimode selectivity simultaneously achievable in a single device. 11. Design and evaluation of a small portable sensor for the determination of ferrocyanide in Hanford waste samples

  7. Cross-modal stimulus conflict: the behavioral effects of stimulus input timing in a visual-auditory Stroop task.

    Science.gov (United States)

    Donohue, Sarah E; Appelbaum, Lawrence G; Park, Christina J; Roberts, Kenneth C; Woldorff, Marty G

    2013-01-01

    Cross-modal processing depends strongly on the compatibility between different sensory inputs, the relative timing of their arrival to brain processing components, and on how attention is allocated. In this behavioral study, we employed a cross-modal audio-visual Stroop task in which we manipulated the within-trial stimulus-onset-asynchronies (SOAs) of the stimulus-component inputs, the grouping of the SOAs (blocked vs. random), the attended modality (auditory or visual), and the congruency of the Stroop color-word stimuli (congruent, incongruent, neutral) to assess how these factors interact within a multisensory context. One main result was that visual distractors produced larger incongruency effects on auditory targets than vice versa. Moreover, as revealed by both overall shorter response times (RTs) and relative shifts in the psychometric incongruency-effect functions, visual-information processing was faster and produced stronger and longer-lasting incongruency effects than did auditory. When attending to either modality, stimulus incongruency from the other modality interacted with SOA, yielding larger effects when the irrelevant distractor occurred prior to the attended target, but no interaction with SOA grouping. Finally, relative to neutral-stimuli, and across the wide range of the SOAs employed, congruency led to substantially more behavioral facilitation than did incongruency to interference, in contrast to findings that within-modality stimulus-compatibility effects tend to be more evenly split between facilitation and interference. In sum, the present findings reveal several key characteristics of how we process the stimulus compatibility of cross-modal sensory inputs, reflecting stimulus processing patterns that are critical for successfully navigating our complex multisensory world.

  8. Cross-modal stimulus conflict: the behavioral effects of stimulus input timing in a visual-auditory Stroop task.

    Directory of Open Access Journals (Sweden)

    Sarah E Donohue

    Full Text Available Cross-modal processing depends strongly on the compatibility between different sensory inputs, the relative timing of their arrival to brain processing components, and on how attention is allocated. In this behavioral study, we employed a cross-modal audio-visual Stroop task in which we manipulated the within-trial stimulus-onset-asynchronies (SOAs of the stimulus-component inputs, the grouping of the SOAs (blocked vs. random, the attended modality (auditory or visual, and the congruency of the Stroop color-word stimuli (congruent, incongruent, neutral to assess how these factors interact within a multisensory context. One main result was that visual distractors produced larger incongruency effects on auditory targets than vice versa. Moreover, as revealed by both overall shorter response times (RTs and relative shifts in the psychometric incongruency-effect functions, visual-information processing was faster and produced stronger and longer-lasting incongruency effects than did auditory. When attending to either modality, stimulus incongruency from the other modality interacted with SOA, yielding larger effects when the irrelevant distractor occurred prior to the attended target, but no interaction with SOA grouping. Finally, relative to neutral-stimuli, and across the wide range of the SOAs employed, congruency led to substantially more behavioral facilitation than did incongruency to interference, in contrast to findings that within-modality stimulus-compatibility effects tend to be more evenly split between facilitation and interference. In sum, the present findings reveal several key characteristics of how we process the stimulus compatibility of cross-modal sensory inputs, reflecting stimulus processing patterns that are critical for successfully navigating our complex multisensory world.

  9. Effects of stimulus duration on gustatory evoked potentials

    DEFF Research Database (Denmark)

    Rotvel, Camilla Arndal; Møller, Stine; Kivisaar, Kätlin

    The objective of the present study was to investigate the effect of tastant stimulus duration on the brain response. The brain response was measured by electroencephalography (EEG) which measures neural processes with high temporal resolution and may therefore complement sensory panel assessments...

  10. Compound Stimulus Extinction Reduces Spontaneous Recovery in Humans

    Science.gov (United States)

    Coelho, Cesar A. O.; Dunsmoor, Joseph E.; Phelps, Elizabeth A.

    2015-01-01

    Fear-related behaviors are prone to relapse following extinction. We tested in humans a compound extinction design ("deepened extinction") shown in animal studies to reduce post-extinction fear recovery. Adult subjects underwent fear conditioning to a visual and an auditory conditioned stimulus (CSA and CSB, respectively) separately…

  11. Switchable adhesion and friction by stimulus responsive polymer brushes

    NARCIS (Netherlands)

    Yu, Yunlong

    2017-01-01

    Controlling friction and adhesion is relevant in nature and in our daily life. Such control can be achieved using stimulus responsive end-anchored polymers forming a brush. These brushes can adapt their physicochemical properties upon changing the surrounding environments, such as temperature,

  12. Psilocybin-induced stimulus control in the rat.

    Science.gov (United States)

    Winter, J C; Rice, K C; Amorosi, D J; Rabin, R A

    2007-10-01

    Although psilocybin has been trained in the rat as a discriminative stimulus, little is known of the pharmacological receptors essential for stimulus control. In the present investigation rats were trained with psilocybin and tests were then conducted employing a series of other hallucinogens and presumed antagonists. An intermediate degree of antagonism of psilocybin was observed following treatment with the 5-HT(2A) receptor antagonist, M100907. In contrast, no significant antagonism was observed following treatment with the 5-HT(1A/7) receptor antagonist, WAY-100635, or the DA D(2) antagonist, remoxipride. Psilocybin generalized fully to DOM, LSD, psilocin, and, in the presence of WAY-100635, DMT while partial generalization was seen to 2C-T-7 and mescaline. LSD and MDMA partially generalized to psilocybin and these effects were completely blocked by M-100907; no generalization of PCP to psilocybin was seen. The present data suggest that psilocybin induces a compound stimulus in which activity at the 5-HT(2A) receptor plays a prominent but incomplete role. In addition, psilocybin differs from closely related hallucinogens such as 5-MeO-DMT in that agonism at 5-HT(1A) receptors appears to play no role in psilocybin-induced stimulus control.

  13. Human cochlear tuning estimates from stimulus-frequency otoacoustic emissions

    DEFF Research Database (Denmark)

    Bentsen, Thomas; Harte, James; Dau, Torsten

    2011-01-01

    Two objective measures of human cochlear tuning, using stimulus-frequency otoacoustic emissions (SFOAE), have been proposed. One measure used SFOAE phase-gradient delay and the other twotone suppression (2TS) tuning curves. Here, it is hypothesized that the two measures lead to different frequency...

  14. Fechnerian metrics in unidimensional and multidimensional stimulus spaces.

    Science.gov (United States)

    Dzhafarov, E N; Colonius, H

    1999-06-01

    A new theory is proposed for subjective (Fechnerian) distances among stimuli in a continuous stimulus space of arbitrary dimensionality. Each stimulus in such a space is associated with a psychometric function that determines probabilities with which it is discriminated from other stimuli, and a certain measure of its discriminability from its infinitesimally close neighboring stimuli is computed from the shape of this psychometric function in the vicinity of its minimum. This measure of discriminability can be integrated along any path connecting any two points in the stimulus space, yielding the psychometric length of this path. The Fechnerian distance between two stimuli is defined as the infimum of the psychometric lengths of all paths connecting the two stimuli. For a broad class of models defining the dichotomy of response bias versus discriminability, the Fechnerian distances are invariant under response bias changes. In the case in which physically multidimensional stimuli are discriminated along some unidimensional subjective attribute, a systematic construction of the Fechnerian metric leads to a resolution of the long-standing controversy related to the numbers of just-noticeable differences between isosensitivity curves. It is argued that for unidimensional stimulus continua, the proposed theory is close to the intended meaning of Fechner's original theory.

  15. Suboptimal Choice in Pigeons: Stimulus Value Predicts Choice over Frequencies.

    Directory of Open Access Journals (Sweden)

    Aaron P Smith

    Full Text Available Pigeons have shown suboptimal gambling-like behavior when preferring a stimulus that infrequently signals reliable reinforcement over alternatives that provide greater reinforcement overall. As a mechanism for this behavior, recent research proposed that the stimulus value of alternatives with more reliable signals for reinforcement will be preferred relatively independently of their frequencies. The present study tested this hypothesis using a simplified design of a Discriminative alternative that, 50% of the time, led to either a signal for 100% reinforcement or a blackout period indicative of 0% reinforcement against a Nondiscriminative alternative that always led to a signal that predicted 50% reinforcement. Pigeons showed a strong preference for the Discriminative alternative that remained despite reducing the frequency of the signal for reinforcement in subsequent phases to 25% and then 12.5%. In Experiment 2, using the original design of Experiment 1, the stimulus following choice of the Nondiscriminative alternative was increased to 75% and then to 100%. Results showed that preference for the Discriminative alternative decreased only when the signals for reinforcement for the two alternatives predicted the same probability of reinforcement. The ability of several models to predict this behavior are discussed, but the terminal link stimulus value offers the most parsimonious account of this suboptimal behavior.

  16. Intermittent stimulus presentation stabilizes neuronal responses in macaque area MT

    NARCIS (Netherlands)

    Klink, P.C.; Oleksiak, A.; Lankheet, M.J.M.; Wezel, R.J.A.

    2012-01-01

    Klink PC, Oleksiak A, Lankheet MJ, van Wezel RJ. Intermittent stimulus presentation stabilizes neuronal responses in macaque area MT. J Neurophysiol 108: 2101-2114, 2012. First published July 25, 2012; doi: 10.1152/jn.00252.2012.-Repeated stimulation impacts neuronal responses. Here we show how

  17. Promoting Response Variability and Stimulus Generalization in Martial Arts Training

    Science.gov (United States)

    Harding, Jay W.; Wacker, David P.; Berg, Wendy K.; Rick, Gary; Lee, John F.

    2004-01-01

    The effects of reinforcement and extinction on response variability and stimulus generalization in the punching and kicking techniques of 2 martial arts students were evaluated across drill and sparring conditions. During both conditions, the students were asked to demonstrate different techniques in response to an instructor's punching attack.…

  18. Validity of electrical stimulus magnitude matching in chronic pain

    DEFF Research Database (Denmark)

    Persson, Ann L; Westermark, Sofia; Merrick, Daniel

    2009-01-01

    OBJECTIVE: To examine the validity of the PainMatcher in chronic pain. DESIGN: Comparison of parallel pain estimates from visual analogue scales with electrical stimulus magnitude matching. PATIENTS: Thirty-one patients with chronic musculoskeletal pain. METHODS: Twice a day ongoing pain was rated...

  19. Effects of Idiosyncratic Stimulus Variables on Functional Analysis Outcomes.

    Science.gov (United States)

    Carr, Edward G.; Yarborough, Scott C.; Langdon, Nancy A.

    1997-01-01

    A study involving three individuals (ages 13-20) with developmental disabilities and problem behaviors examined the influential role that unanticipated idiosyncratic stimulus variables play in affecting the outcome of a functional analysis. Guidelines are discussed concerning when to suspect that idiosyncratic stimuli might be acting to influence…

  20. Stimulus Characteristics Affect Humor Processing in Individuals with Asperger Syndrome

    Science.gov (United States)

    Samson, Andrea C.; Hegenloh, Michael

    2010-01-01

    The present paper aims to investigate whether individuals with Asperger syndrome (AS) show global humor processing deficits or whether humor comprehension and appreciation depends on stimulus characteristics. Non-verbal visual puns, semantic and Theory of Mind cartoons were rated on comprehension, funniness and the punchlines were explained. AS…

  1. ‘N-of-1-pathways’ unveils personal deregulated mechanisms from a single pair of RNA-Seq samples: towards precision medicine

    Science.gov (United States)

    Gardeux, Vincent; Achour, Ikbel; Li, Jianrong; Maienschein-Cline, Mark; Li, Haiquan; Pesce, Lorenzo; Parinandi, Gurunadh; Bahroos, Neil; Winn, Robert; Foster, Ian; Garcia, Joe G N; Lussier, Yves A

    2014-01-01

    Background The emergence of precision medicine allowed the incorporation of individual molecular data into patient care. Indeed, DNA sequencing predicts somatic mutations in individual patients. However, these genetic features overlook dynamic epigenetic and phenotypic response to therapy. Meanwhile, accurate personal transcriptome interpretation remains an unmet challenge. Further, N-of-1 (single-subject) efficacy trials are increasingly pursued, but are underpowered for molecular marker discovery. Method ‘N-of-1-pathways’ is a global framework relying on three principles: (i) the statistical universe is a single patient; (ii) significance is derived from geneset/biomodules powered by paired samples from the same patient; and (iii) similarity between genesets/biomodules assesses commonality and differences, within-study and cross-studies. Thus, patient gene-level profiles are transformed into deregulated pathways. From RNA-Seq of 55 lung adenocarcinoma patients, N-of-1-pathways predicts the deregulated pathways of each patient. Results Cross-patient N-of-1-pathways obtains comparable results with conventional genesets enrichment analysis (GSEA) and differentially expressed gene (DEG) enrichment, validated in three external evaluations. Moreover, heatmap and star plots highlight both individual and shared mechanisms ranging from molecular to organ-systems levels (eg, DNA repair, signaling, immune response). Patients were ranked based on the similarity of their deregulated mechanisms to those of an independent gold standard, generating unsupervised clusters of diametric extreme survival phenotypes (p=0.03). Conclusions The N-of-1-pathways framework provides a robust statistical and relevant biological interpretation of individual disease-free survival that is often overlooked in conventional cross-patient studies. It enables mechanism-level classifiers with smaller cohorts as well as N-of-1 studies. Software http://lussierlab.org/publications/N-of-1-pathways

  2. Fully automated ionic liquid-based headspace single drop microextraction coupled to GC-MS/MS to determine musk fragrances in environmental water samples.

    Science.gov (United States)

    Vallecillos, Laura; Pocurull, Eva; Borrull, Francesc

    2012-09-15

    A fully automated ionic liquid-based headspace single drop microextraction (IL-HS-SDME) procedure has been developed for the first time to preconcentrate trace amounts of ten musk fragrances extensively used in personal care products (six polycyclic musks, three nitro musks and one polycyclic musk degradation product) from wastewater samples prior to analysis by gas chromatography and ion trap tandem mass spectrometry (GC-IT-MS/MS). Due to the low volatility of the ILs, a large internal diameter liner (3.4 mm i.d.) was used to improve the ILs evaporation. Furthermore, a piece of glass wool was introduced into the liner to avoid the entrance of the ILs in the GC column and a guard column was used to prevent analytical column damages. The main factors influencing the IL-HS-SDME were optimized. For all species, the highest enrichments factors were achieved using 1 μL of 1-octyl-3-methylimidazolium hexafluorophosphate ([OMIM][PF(6)]) ionic liquid exposed in the headspace of 10 mL water samples containing 300 g L(-1) of NaCl and stirred at 750 rpm and 60 °C for 45 min. All compounds were determined by direct injection GC-IT-MS/MS with a chromatographic time of 19 min. Method detection limits were found in the low ng mL(-1) range between 0.010 ng mL(-1) and 0.030 ng mL(-1) depending on the target analytes. Also, under optimized conditions, the method gave good levels of intra-day and inter-day repeatabilities in wastewater samples with relative standard deviations varying between 3% and 6% and 5% and 11%, respectively (n=3, 1 ng mL(-1)). The applicability of the method was tested with different wastewater samples from influent and effluent urban wastewater treatment plants (WWTPs) and one potable treatment plant (PTP). The analysis of influent urban wastewater revealed the presence of galaxolide and tonalide at concentrations of between 2.10 ng mL(-1) and 0.29 ng mL(-1) and 0.32 ng mL(-1) and MQL (Method Quantification Limit), respectively; while the remaining

  3. Collective Ion-Pair Single-Drop Microextraction Attenuated Total Reflectance Fourier Transform Infrared Spectroscopic Determination of Perchlorate in Bioenvironmental Samples.

    Science.gov (United States)

    Chandrawanshi, Swati; Verma, Santosh K; Deb, Manas K

    2017-09-28

    Perchlorate (ClO₄ - ) is an environmental pollutant that affects human health. Perchlorate acts as a competitive inhibitor of iodine uptake in the thyroid gland (sodium-iodide symporter inhibitor); thus, its determination is important for public health concerns. Water and milk constitute a significant portion of the human diet. Because regular intake leads to an increase in perchlorate concentration in the human body, the estimation of perchlorate is of great concern. In this work, ion-pair single-drop microextraction (SDME) combined with attenuated total reflectance (ATR)-FTIR spectroscopy has been developed for the determination of perchlorate in bioenvironmental (soil, water, dairy milk, breast milk, and urine) samples. Perchlorate was extracted in a single drop of methyl isobutyl ketone as an - with the cationic surfactant cetyltrimethylammonuim bromide under optimized conditions. The strongest IR peak (at 1076 cm -1 ) was selected for the quantification of perchlorate among three observed vibrational peaks. Eight calibration curves for different concentration ranges of perchlorate were prepared, and excellent linearity was observed for absorbance and peak area in the range of 0.03-100 ng/mL perchlorate, with r values of 0.977 and 0.976, respectively. The RSDs ( n = 8) for the perchlorate concentration ranges of 0.03-100, 0.03-0.5, 0.5-10, and 10-100 ng/mL were in the range of 1.9-2.7% for the above calibration curves. The LOD and LOQ in the present work were 0.003 and 0.02 ng/mL, respectively. The extracted microdrop was analyzed directly by ATR-FTIR spectroscopy. The parameters affecting SDME, i.e, effect of pH, stirring rate, reagent concentration, microdrop volume, and extraction time, were optimized, and the role of foreign species was also investigated. F - and t -tests were performed to check the analytical QA of the method. A noteworthy feature of the reported method is the noninterference of any of the associated ions. The results were compared with

  4. Folic acid absorption determined by a single stool sample test--a double-isotope technique. The folic acid absorption capacity in children.

    Science.gov (United States)

    Hjelt, K

    1989-10-01

    The fractional folic acid absorption (FAFol) was determined in 66 patients with various gastrointestinal diseases by a double-isotope technique, employing a single stool sample test (SSST) as well as a complete stool collection. The age of the patients ranged from 2.5 months to 16.8 years (mean 6.3 years). The test dose was administered orally and consisted of 50 micrograms of [3H]folic acid (monoglutamate) (approximately 20 muCi), carmine powder, and 2 mg 51CrCl3 (approximately 1.25 muCi) as the unabsorbable tracer. The whole-body radiation given to a 1-year-old child averaged 4.8 mrad only. The stool and napkin contents were collected and homogenized by the addition of 300 ml chromium sulfuric acid. A 300-ml sample of the homogenized stool and napkin contents, as well as 300 ml chromium sulfuric acid (75% vol/vol) containing the standards, were counted for the content of 51Cr in a broad-based well counter. The quantity of [3H]folic acid was determined by liquid scintillation, after duplicate distillation. Estimated by SSST, the FAFol, which employs the stool with the highest content of 51Cr corresponding to the most carmine-colored stool, correlated closely with the FAFol based on complete stool collection (r = 0.96, n = 39, p less than 0.0001). The reproducibility of FAFol determined by SSST was assessed from repeated tests in 18 patients. For a mean of 81%, the SD was 4.6%, which corresponded to a coefficient of variation of 5.7%.(ABSTRACT TRUNCATED AT 250 WORDS)

  5. High transport efficiency of nanoparticles through a total-consumption sample introduction system and its beneficial application for particle size evaluation in single-particle ICP-MS.

    Science.gov (United States)

    Miyashita, Shin-Ichi; Mitsuhashi, Hiroaki; Fujii, Shin-Ichiro; Takatsu, Akiko; Inagaki, Kazumi; Fujimoto, Toshiyuki

    2017-02-01

    In order to facilitate reliable and efficient determination of both the particle number concentration (PNC) and the size of nanoparticles (NPs) by single-particle ICP-MS (spICP-MS) without the need to correct for the particle transport efficiency (TE, a possible source of bias in the results), a total-consumption sample introduction system consisting of a large-bore, high-performance concentric nebulizer and a small-volume on-axis cylinder chamber was utilized. Such a system potentially permits a particle TE of 100 %, meaning that there is no need to include a particle TE correction when calculating the PNC and the NP size. When the particle TE through the sample introduction system was evaluated by comparing the frequency of sharp transient signals from the NPs in a measured NP standard of precisely known PNC to the particle frequency for a measured NP suspension, the TE for platinum NPs with a nominal diameter of 70 nm was found to be very high (i.e., 93 %), and showed satisfactory repeatability (relative standard deviation of 1.0 % for four consecutive measurements). These results indicated that employing this total consumption system allows the particle TE correction to be ignored when calculating the PNC. When the particle size was determined using a solution-standard-based calibration approach without an NP standard, the particle diameters of platinum and silver NPs with nominal diameters of 30-100 nm were found to agree well with the particle diameters determined by transmission electron microscopy, regardless of whether a correction was performed for the particle TE. Thus, applying the proposed system enables NP size to be accurately evaluated using a solution-standard-based calibration approach without the need to correct for the particle TE.

  6. Feasibility of a Humor Training to Promote Humor and Decrease Stress in a Subclinical Sample: A Single-Arm Pilot Study

    Directory of Open Access Journals (Sweden)

    Nektaria Tagalidou

    2018-04-01

    Full Text Available The present study investigates the feasibility of a humor training for a subclinical sample suffering from increased stress, depressiveness, or anxiety. Based on diagnostic interviews, 35 people were invited to participate in a 7-week humor training. Evaluation measures were filled in prior training, after training, and at a 1-month follow-up including humor related outcomes (coping humor and cheerfulness and mental health-related outcomes (perceived stress, depressiveness, anxiety, and well-being. Outcomes were analyzed using repeated-measures ANOVAs. Within-group comparisons of intention-to-treat analysis showed main effects of time with large effect sizes on all outcomes. Post hoc tests showed medium to large effect sizes on all outcomes from pre to post and results remained stable until follow-up. Satisfaction with the training was high, attrition rate low (17.1%, and participants would highly recommend the training. Summarizing the results, the pilot study showed promising effects for people suffering from subclinical symptoms. All outcomes were positively influenced and showed stability over time. Humor trainings could be integrated more into mental health care as an innovative program to reduce stress whilst promoting also positive emotions. However, as this study was a single-arm pilot study, further research (including also randomized controlled trials is still needed to evaluate the effects more profoundly.

  7. Applying meta-pathway analyses through metagenomics to identify the functional properties of the major bacterial communities of a single spontaneous cocoa bean fermentation process sample.

    Science.gov (United States)

    Illeghems, Koen; Weckx, Stefan; De Vuyst, Luc

    2015-09-01

    A high-resolution functional metagenomic analysis of a representative single sample of a Brazilian spontaneous cocoa bean fermentation process was carried out to gain insight into its bacterial community functioning. By reconstruction of microbial meta-pathways based on metagenomic data, the current knowledge about the metabolic capabilities of bacterial members involved in the cocoa bean fermentation ecosystem was extended. Functional meta-pathway analysis revealed the distribution of the metabolic pathways between the bacterial members involved. The metabolic capabilities of the lactic acid bacteria present were most associated with the heterolactic fermentation and citrate assimilation pathways. The role of Enterobacteriaceae in the conversion of substrates was shown through the use of the mixed-acid fermentation and methylglyoxal detoxification pathways. Furthermore, several other potential functional roles for Enterobacteriaceae were indicated, such as pectinolysis and citrate assimilation. Concerning acetic acid bacteria, metabolic pathways were partially reconstructed, in particular those related to responses toward stress, explaining their metabolic activities during cocoa bean fermentation processes. Further, the in-depth metagenomic analysis unveiled functionalities involved in bacterial competitiveness, such as the occurrence of CRISPRs and potential bacteriocin production. Finally, comparative analysis of the metagenomic data with bacterial genomes of cocoa bean fermentation isolates revealed the applicability of the selected strains as functional starter cultures. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. Different target-discrimination times can be followed by the same saccade-initiation timing in different stimulus conditions during visual searches

    Science.gov (United States)

    Tanaka, Tomohiro; Nishida, Satoshi

    2015-01-01

    The neuronal processes that underlie visual searches can be divided into two stages: target discrimination and saccade preparation/generation. This predicts that the length of time of the prediscrimination stage varies according to the search difficulty across different stimulus conditions, whereas the length of the latter postdiscrimination stage is stimulus invariant. However, recent studies have suggested that the length of the postdiscrimination interval changes with different stimulus conditions. To address whether and how the visual stimulus affects determination of the postdiscrimination interval, we recorded single-neuron activity in the lateral intraparietal area (LIP) when monkeys (Macaca fuscata) performed a color-singleton search involving four stimulus conditions that differed regarding luminance (Bright vs. Dim) and target-distractor color similarity (Easy vs. Difficult). We specifically focused on comparing activities between the Bright-Difficult and Dim-Easy conditions, in which the visual stimuli were considerably different, but the mean reaction times were indistinguishable. This allowed us to examine the neuronal activity when the difference in the degree of search speed between different stimulus conditions was minimal. We found that not only prediscrimination but also postdiscrimination intervals varied across stimulus conditions: the postdiscrimination interval was longer in the Dim-Easy condition than in the Bright-Difficult condition. Further analysis revealed that the postdiscrimination interval might vary with stimulus luminance. A computer simulation using an accumulation-to-threshold model suggested that the luminance-related difference in visual response strength at discrimination time could be the cause of different postdiscrimination intervals. PMID:25995344

  9. Fine-grained stimulus representations in body selective areas of human occipito-temporal cortex.

    Science.gov (United States)

    Caspari, Natalie; Popivanov, Ivo D; De Mazière, Patrick A; Vanduffel, Wim; Vogels, Rufin; Orban, Guy A; Jastorff, Jan

    2014-11-15

    Neurophysiological and functional imaging studies have investigated the representation of animate and inanimate stimulus classes in monkey inferior temporal (IT) and human occipito-temporal cortex (OTC). These studies proposed a distributed representation of stimulus categories across IT and OTC and at the same time highlighted category specific modules for the processing of bodies, faces and objects. Here, we investigated whether the stimulus representation within the extrastriate (EBA) and the fusiform (FBA) body areas differed from the representation across OTC. To address this question, we performed an event-related fMRI experiment, evaluating the pattern of activation elicited by 200 individual stimuli that had already been extensively tested in our earlier monkey imaging and single cell studies (Popivanov et al., 2012, 2014). The set contained achromatic images of headless monkey and human bodies, two sets of man-made objects, monkey and human faces, four-legged mammals, birds, fruits, and sculptures. The fMRI response patterns within EBA and FBA primarily distinguished bodies from non-body stimuli, with subtle differences between the areas. However, despite responding on average stronger to bodies than to other categories, classification performance for preferred and non-preferred categories was comparable. OTC primarily distinguished animate from inanimate stimuli. However, cluster analysis revealed a much more fine-grained representation with several homogeneous clusters consisting entirely of stimuli of individual categories. Overall, our data suggest that category representation varies with location within OTC. Nevertheless, body modules contain information to discriminate also non-preferred stimuli and show an increasing specificity in a posterior to anterior gradient. Copyright © 2014 Elsevier Inc. All rights reserved.

  10. Effects of stimulus duration on gustatory evoked potentials

    DEFF Research Database (Denmark)

    Rotvel, Camilla Arndal; Møller, Stine; Kivisaar, Kätlin

    The objective of the present study was to investigate the effect of tastant stimulus duration on the brain response. The brain response was measured by electroencephalography (EEG) which measures neural processes with high temporal resolution and may therefore complement sensory panel assessments....... 19 normal-tasting subjects (10 females, mean age ± sd: 27 ± 3) were stimulated with aqueous 0.5g/L sucralose in between continuous periods of non-chlorinated tap water to avoid somatosensory onsets. The sucralose stimulus duration was either short (~0.6s) or long (~4s) and presented in random...... sequence with 60 repetitions. The stimuli were delivered to the center of the tongue apex innervated by chorda tympani nerve. Brain response was recorded with 128 electrodes and the gustatory event related potential (GEP) was estimated by coherent averaging of all artefact free epochs. Focusing on the FC5...

  11. Gambling with stimulus payments: feeding gaming machines with federal dollars.

    Science.gov (United States)

    Lye, Jenny; Hirschberg, Joe

    2014-09-01

    In late 2008 and early 2009 the Australian Federal Government introduced a series of economic stimulus packages designed to maintain consumer spending in the early days of the Great Recession. When these packages were initiated the media suggested that the wide-spread availability of electronic gaming machines (EGMs, e.g. slot machines, poker machines, video lottery terminals) in Australia would result in stimulating the EGMs. Using state level monthly data we estimate that the stimulus packages led to an increase of 26 % in EGM revenues. This also resulted in over $60 million in additional tax revenue for State Governments. We also estimate a short-run aggregate income demand elasticity for EGMs to be approximately 2.

  12. The Duration of Motor Responses Evoked with Intracortical Microstimulation in Rats Is Primarily Modulated by Stimulus Amplitude and Train Duration.

    Directory of Open Access Journals (Sweden)

    Meghan Watson

    Full Text Available Microstimulation of brain tissue plays a key role in a variety of sensory prosthetics, clinical therapies and research applications, however the effects of stimulation parameters on the responses they evoke remain widely unknown. In particular, the effects of parameters when delivered in the form of a stimulus train as opposed to a single pulse are not well understood despite the prevalence of stimulus train use. We aimed to investigate the contribution of each parameter of a stimulus train to the duration of the motor responses they evoke in forelimb muscles. We used constant-current, biphasic, square wave pulse trains in acute terminal experiments under ketamine anaesthesia. Stimulation parameters were systematically tested in a pair-wise fashion in the caudal forelimb region of the motor cortex in 7 Sprague-Dawley rats while motor evoked potential (MEP recordings from the forelimb were used to quantify the influence of each parameter in the train. Stimulus amplitude and train duration were shown to be the dominant parameters responsible for increasing the total duration of the MEP, while interphase interval had no effect. Increasing stimulus frequency from 100-200 Hz or pulse duration from 0.18-0.34 ms were also effective methods of extending response durations. Response duration was strongly correlated with peak time and amplitude. Our findings suggest that motor cortex intracortical microstimulations are often conducted at a higher frequency rate and longer train duration than necessary to evoke maximal response duration. We demonstrated that the temporal properties of the evoked response can be both predicted by certain response metrics and modulated via alterations to the stimulation signal parameters.

  13. The Duration of Motor Responses Evoked with Intracortical Microstimulation in Rats Is Primarily Modulated by Stimulus Amplitude and Train Duration.

    Science.gov (United States)

    Watson, Meghan; Sawan, Mohamad; Dancause, Numa

    2016-01-01

    Microstimulation of brain tissue plays a key role in a variety of sensory prosthetics, clinical therapies and research applications, however the effects of stimulation parameters on the responses they evoke remain widely unknown. In particular, the effects of parameters when delivered in the form of a stimulus train as opposed to a single pulse are not well understood despite the prevalence of stimulus train use. We aimed to investigate the contribution of each parameter of a stimulus train to the duration of the motor responses they evoke in forelimb muscles. We used constant-current, biphasic, square wave pulse trains in acute terminal experiments under ketamine anaesthesia. Stimulation parameters were systematically tested in a pair-wise fashion in the caudal forelimb region of the motor cortex in 7 Sprague-Dawley rats while motor evoked potential (MEP) recordings from the forelimb were used to quantify the influence of each parameter in the train. Stimulus amplitude and train duration were shown to be the dominant parameters responsible for increasing the total duration of the MEP, while interphase interval had no effect. Increasing stimulus frequency from 100-200 Hz or pulse duration from 0.18-0.34 ms were also effective methods of extending response durations. Response duration was strongly correlated with peak time and amplitude. Our findings suggest that motor cortex intracortical microstimulations are often conducted at a higher frequency rate and longer train duration than necessary to evoke maximal response duration. We demonstrated that the temporal properties of the evoked response can be both predicted by certain response metrics and modulated via alterations to the stimulation signal parameters.

  14. Neuronal oscillations enhance stimulus discrimination by ensuring action potential precision

    DEFF Research Database (Denmark)

    Schaefer, Andreas T; Angelo, Kamilla; Spors, Hartwig

    2006-01-01

    --permitted accurate discernment of up to 1,000 different stimuli. At low oscillation frequencies, stimulus discrimination showed a clear phase dependence whereby inputs arriving during the trough and the early rising phase of an oscillation cycle were most robustly discriminated. Thus, by ensuring AP precision......, membrane potential oscillations dramatically enhance the discriminatory capabilities of individual neurons and networks of cells and provide one attractive explanation for their abundance in neurophysiological systems....

  15. Does supernormal stimulus influence parental behaviour of the cuckoo's host?

    Czech Academy of Sciences Publication Activity Database

    Grim, T.; Honza, Marcel

    2001-01-01

    Roč. 49, č. 4 (2001), s. 322-329 ISSN 0340-5443 R&D Projects: GA AV ČR IAA6087801; GA AV ČR KSK2005601; GA MŠk VS96019 Institutional research plan: CEZ:AV0Z6093917 Keywords : brood parasitism * supernormal stimulus * parental care Subject RIV: EG - Zoology Impact factor: 2.353, year: 2001

  16. Combining single-particle inductively coupled plasma mass spectrometry and X-ray absorption spectroscopy to evaluate the release of colloidal arsenic from environmental samples.

    Science.gov (United States)

    Gomez-Gonzalez, Miguel Angel; Bolea, Eduardo; O'Day, Peggy A; Garcia-Guinea, Javier; Garrido, Fernando; Laborda, Francisco

    2016-07-01

    Detection and sizing of natural colloids involved in the release and transport of toxic metals and metalloids is essential to understand and model their environmental effects. Single-particle inductively coupled plasma mass spectrometry (SP-ICP-MS) was applied for the detection of arsenic-bearing particles released from mine wastes. Arsenic-bearing particles were detected in leachates from mine wastes, with a mass-per-particle detection limit of 0.64 ng of arsenic. Conversion of the mass-per-particle information provided by SP-ICP-MS into size information requires knowledge of the nature of the particles; therefore, synchrotron-based X-ray absorption spectroscopy (XAS) was used to identify scorodite (FeAsO4·2H2O) as the main species in the colloidal particles isolated by ultrafiltration. The size of the scorodite particles detected in the leachates was below 300-350 nm, in good agreement with the values obtained by TEM. The size of the particles detected by SP-ICP-MS was determined as the average edge of scorodite crystals, which show a rhombic dipyramidal form, achieving a size detection limit of 117 nm. The combined use of SP-ICP-MS and XAS allowed detection, identification, and size determination of scorodite particles released from mine wastes, suggesting their potential to transport arsenic. Graphical abstract Analytical approach for the detection and size characterization of As-bearing particles by SP-ICP-MS and XAS in environmental samples.

  17. Chicken single-chain antibody fused to alkaline phosphatase detects Aspergillus pathogens and their presence in natural samples by direct sandwich enzyme-linked immunosorbent assay.

    Science.gov (United States)

    Xue, Sheng; Li, He-Ping; Zhang, Jing-Bo; Liu, Jin-Long; Hu, Zu-Quan; Gong, An-Dong; Huang, Tao; Liao, Yu-Cai

    2013-11-19

    A sensitive and specific analytical method to detect ubiquitous aflatoxigenic Aspergillus pathogens is essential for monitoring and controlling aflatoxins. Four highly reactive chicken single-chain variable fragments (scFvs) against soluble cell wall proteins (SCWPs) from Aspergillus flavus were isolated by phage display. The scFv antibody AfSA4 displayed the highest activity toward both A. flavus and A. parasiticus and specifically recognized a surface target of their cell walls as revealed by immunofluorescence localization. Molecular modeling revealed a unique compact motif on the antibody surface mainly involving L-CDR2 and H-CDR3. As measured by surface plasmon resonance, AfSA4 fused to alkaline phosphatase had a higher binding capability and 6-fold higher affinity compared with AfSA4 alone. Immunoblot analyses showed that the fusion had good binding capacity to SCWP components from the two fungal species. Direct sandwich enzyme-linked immunosorbent assays with mouse antiaspergillus monoclonal antibody mAb2A8 generated in parallel as a capture antibody revealed that the detection limit of the two fungi was as low as 10(-3) μg/mL, 1000-fold more sensitive than that reported previously (1 μg/mL). The fusion protein was able to detect fungal concentrations below 1 μg/g of maize and peanut grains in both artificially and naturally contaminated samples, with at least 10-fold more sensitivity than that reported (10 μg/g) thus far. Thus, the fusion can be applied in rapid, simple, and specific diagnosis of Aspergillus contamination in field and stored food/feed commodities.

  18. 3D-TROSY-based backbone and ILV-methyl resonance assignments of a 319-residue homodimer from a single protein sample

    Energy Technology Data Exchange (ETDEWEB)

    Krejcirikova, Anna; Tugarinov, Vitali, E-mail: vitali@umd.edu [University of Maryland, Department of Chemistry and Biochemistry (United States)

    2012-10-15

    The feasibility of practically complete backbone and ILV methyl chemical shift assignments from a single [U-{sup 2}H,{sup 15}N,{sup 13}C; Ile{delta}1-{l_brace}{sup 13}CH{sub 3}{r_brace}; Leu,Val-{l_brace}{sup 13}CH{sub 3}/{sup 12}CD{sub 3}{r_brace}]-labeled protein sample of the truncated form of ligand-free Bst-Tyrosyl tRNA Synthetase (Bst-{Delta}YRS), a 319-residue predominantly helical homodimer, is established. Protonation of ILV residues at methyl positions does not appreciably detract from the quality of TROSY triple resonance data. The assignments are performed at 40 Degree-Sign C to improve the sensitivity of the measurements and alleviate the overlap of {sup 1}H-{sup 15}N correlations in the abundant {alpha}-helical segments of the protein. A number of auxiliary approaches are used to assist in the assignment process: (1) selection of {sup 1}H-{sup 15}N amide correlations of certain residue types (Ala, Thr/Ser) that simplifies 2D {sup 1}H-{sup 15}N TROSY spectra, (2) straightforward identification of ILV residue types from the methyl-detected 'out-and-back' HMCM(CG)CBCA experiment, and (3) strong sequential HN-HN NOE connectivities in the helical regions. The two subunits of Bst-YRS were predicted earlier to exist in two different conformations in the absence of ligands. In agreement with our earlier findings (Godoy-Ruiz in J Am Chem Soc 133:19578-195781, 2011), no evidence of dimer asymmetry has been observed in either amide- or methyl-detected experiments.

  19. Robustness of two single-item self-esteem measures: cross-validation with a measure of stigma in a sample of psychiatric patients.

    Science.gov (United States)

    Bagley, Christopher

    2005-08-01

    Robins' Single-item Self-esteem Inventory was compared with a single item from the Coopersmith Self-esteem. Although a new scoring format was used, there was good evidence of cross-validation in 83 current and former psychiatric patients who completed Harvey's adapted measure of stigma felt and experienced by users of mental health services. Scores on the two single-item self-esteem measures correlated .76 (p self-esteem in users of mental health services.

  20. High Stimulus-Related Information in Barrel Cortex Inhibitory Interneurons.

    Directory of Open Access Journals (Sweden)

    Vicente Reyes-Puerta

    2015-06-01

    Full Text Available The manner in which populations of inhibitory (INH and excitatory (EXC neocortical neurons collectively encode stimulus-related information is a fundamental, yet still unresolved question. Here we address this question by simultaneously recording with large-scale multi-electrode arrays (of up to 128 channels the activity of cell ensembles (of up to 74 neurons distributed along all layers of 3-4 neighboring cortical columns in the anesthetized adult rat somatosensory barrel cortex in vivo. Using two different whisker stimulus modalities (location and frequency we show that individual INH neurons--classified as such according to their distinct extracellular spike waveforms--discriminate better between restricted sets of stimuli (≤6 stimulus classes than EXC neurons in granular and infra-granular layers. We also demonstrate that ensembles of INH cells jointly provide as much information about such stimuli as comparable ensembles containing the ~20% most informative EXC neurons, however presenting less information redundancy - a result which was consistent when applying both theoretical information measurements and linear discriminant analysis classifiers. These results suggest that a consortium of INH neurons dominates the information conveyed to the neocortical network, thereby efficiently processing incoming sensory activity. This conclusion extends our view on the role of the inhibitory system to orchestrate cortical activity.

  1. Accommodative Stimulus-Response Curve with Emoji Symbols.

    Science.gov (United States)

    Montés-Micó, Robert; Esteve Taboada, José J; Bernal-Molina, Paula; Ferrer-Blasco, Teresa

    2017-01-01

    To evaluate the static measurement of the accommodative stimulus-response curve with emoji symbols. The accommodative stimulus-response curve was measured in 18 subjects using a Hartmann-Shack sensor to obtain the objective accommodative response from the Zernike defocus term. Measurements were acquired at different accommodative demands, from 0 to 3 D with a step of 0.5 D. Detailed and nondetailed emoji targets were used with two different sizes, corresponding to the two most common visual angles used in smartphones. A regression analysis was performed to fit the mean results obtained for each target. The determination coefficient was R 2 ≥ 0.988 for all targets. For the detailed targets, the slopes for the averaged stimulus-response curve were 0.65 and 0.66 for the bigger and smaller sizes, respectively. For the nondetailed targets, the slopes were 0.60 and 0.58 for the bigger and smaller sizes, respectively. p values for these slopes were statistically significant for the two types of targets ( p emoji symbols seems not to provoke a different accommodative response in normal subjects and under standard viewing conditions in the use of smartphones.

  2. Accommodative Stimulus-Response Curve with Emoji Symbols

    Directory of Open Access Journals (Sweden)

    Robert Montés-Micó

    2017-01-01

    Full Text Available Purpose. To evaluate the static measurement of the accommodative stimulus-response curve with emoji symbols. Methods. The accommodative stimulus-response curve was measured in 18 subjects using a Hartmann-Shack sensor to obtain the objective accommodative response from the Zernike defocus term. Measurements were acquired at different accommodative demands, from 0 to 3 D with a step of 0.5 D. Detailed and nondetailed emoji targets were used with two different sizes, corresponding to the two most common visual angles used in smartphones. Results. A regression analysis was performed to fit the mean results obtained for each target. The determination coefficient was R2≥0.988 for all targets. For the detailed targets, the slopes for the averaged stimulus-response curve were 0.65 and 0.66 for the bigger and smaller sizes, respectively. For the nondetailed targets, the slopes were 0.60 and 0.58 for the bigger and smaller sizes, respectively. p values for these slopes were statistically significant for the two types of targets (p<0.01. Conclusions. Our results reveal that the replacement of a word or several words by detailed or nondetailed emoji symbols seems not to provoke a different accommodative response in normal subjects and under standard viewing conditions in the use of smartphones.

  3. Accommodative Stimulus-Response Curve with Emoji Symbols

    Science.gov (United States)

    Montés-Micó, Robert; Bernal-Molina, Paula; Ferrer-Blasco, Teresa

    2017-01-01

    Purpose To evaluate the static measurement of the accommodative stimulus-response curve with emoji symbols. Methods The accommodative stimulus-response curve was measured in 18 subjects using a Hartmann-Shack sensor to obtain the objective accommodative response from the Zernike defocus term. Measurements were acquired at different accommodative demands, from 0 to 3 D with a step of 0.5 D. Detailed and nondetailed emoji targets were used with two different sizes, corresponding to the two most common visual angles used in smartphones. Results A regression analysis was performed to fit the mean results obtained for each target. The determination coefficient was R2 ≥ 0.988 for all targets. For the detailed targets, the slopes for the averaged stimulus-response curve were 0.65 and 0.66 for the bigger and smaller sizes, respectively. For the nondetailed targets, the slopes were 0.60 and 0.58 for the bigger and smaller sizes, respectively. p values for these slopes were statistically significant for the two types of targets (p emoji symbols seems not to provoke a different accommodative response in normal subjects and under standard viewing conditions in the use of smartphones. PMID:29082040

  4. Acetylcholine release in the hippocampus during the operant conditioned reflex and the footshock stimulus in rats.

    Science.gov (United States)

    Dong, Yu; Mao, Jianjun; Shangguan, Dihua; Zhao, Rui; Liu, Guoquan

    2004-10-14

    The activity of the septo-hippocampal cholinergic pathway was investigated by measuring changes in the extracellular acetylcholine (ACh) levels in the hippocampus, by means of microdialysis, during the operant conditioned reflex and the repeated footshock stimulus. Microdialysis samplings were conducted in a Skinner box where lights were delivered as conditioned stimuli (CS) paired with footshocks as unconditioned stimuli (US). Two groups of rats were used. Extracellular ACh and choline (Ch) in samples collected at 6min intervals were assessed by high-performance liquid chromatography with electrochemical detection. The elevation of hippocampus ACh was observed in the two experimental groups. The increase in ACh during aversive stimulus (footshock) was significantly larger and was probably related to the number of footshocks. There might be moderate increase in the hippocampal ACh release during the retrieval of information. The concentration of choline showed no significant fluctuation in the two groups during the whole process. This experiment explored in more detail hippocampal cholinergic activity in relation to the two different procedures.

  5. The reference frame for encoding and retention of motion depends on stimulus set size.

    Science.gov (United States)

    Huynh, Duong; Tripathy, Srimant P; Bedell, Harold E; Öğmen, Haluk

    2017-04-01

    The goal of this study was to investigate the reference frames used in perceptual encoding and storage of visual motion information. In our experiments, observers viewed multiple moving objects and reported the direction of motion of a randomly selected item. Using a vector-decomposition technique, we computed performance during smooth pursuit with respect to a spatiotopic (nonretinotopic) and to a retinotopic component and compared them with performance during fixation, which served as the baseline. For the stimulus encoding stage, which precedes memory, we found that the reference frame depends on the stimulus set size. For a single moving target, the spatiotopic reference frame had the most significant contribution with some additional contribution from the retinotopic reference frame. When the number of items increased (Set Sizes 3 to 7), the spatiotopic reference frame was able to account for the performance. Finally, when the number of items became larger than 7, the distinction between reference frames vanished. We interpret this finding as a switch to a more abstract nonmetric encoding of motion direction. We found that the retinotopic reference frame was not used in memory. Taken together with other studies, our results suggest that, whereas a retinotopic reference frame may be employed for controlling eye movements, perception and memory use primarily nonretinotopic reference frames. Furthermore, the use of nonretinotopic reference frames appears to be capacity limited. In the case of complex stimuli, the visual system may use perceptual grouping in order to simplify the complexity of stimuli or resort to a nonmetric abstract coding of motion information.

  6. Brief exposure to sensory cues elicits stimulus-nonspecific general sensitization in an insect.

    Directory of Open Access Journals (Sweden)

    Sebastian Minoli

    Full Text Available The effect of repeated exposure to sensory stimuli, with or without reward is well known to induce stimulus-specific modifications of behaviour, described as different forms of learning. In recent studies we showed that a brief single pre-exposure to the female-produced sex pheromone or even a predator sound can increase the behavioural and central nervous responses to this pheromone in males of the noctuid moth Spodoptera littoralis. To investigate if this increase in sensitivity might be restricted to the pheromone system or is a form of general sensitization, we studied here if a brief pre-exposure to stimuli of different modalities can reciprocally change behavioural and physiological responses to olfactory and gustatory stimuli. Olfactory and gustatory pre-exposure and subsequent behavioural tests were carried out to reveal possible intra- and cross-modal effects. Attraction to pheromone, monitored with a locomotion compensator, increased after exposure to olfactory and gustatory stimuli. Behavioural responses to sucrose, investigated using the proboscis extension reflex, increased equally after pre-exposure to olfactory and gustatory cues. Pheromone-specific neurons in the brain and antennal gustatory neurons did, however, not change their sensitivity after sucrose exposure. The observed intra- and reciprocal cross-modal effects of pre-exposure may represent a new form of stimulus-nonspecific general sensitization originating from modifications at higher sensory processing levels.

  7. Performance enhancement of the single-phase series active filter by employing the load voltage waveform reconstruction and line current sampling delay reduction methods

    DEFF Research Database (Denmark)

    Senturk, O.S.; Hava, A.M.

    2011-01-01

    This paper proposes the waveform reconstruction method (WRM), which is utilized in the single-phase series active filter's (SAF's) control algorithm, in order to extract the load harmonic voltage component of voltage harmonic type single-phase diode rectifier loads. Employing WRM and the line...

  8. MANFAAT STIMULUS VERTEBRA CERVIKALIS KE 5-6 DAN STIMULUS OTOT RECTUS ABDOMINIS TERHADAP PERUBAHAN TFU IBU POST PARTUM PER VAGINAM

    Directory of Open Access Journals (Sweden)

    Suryanti Suryanti

    2017-02-01

    Full Text Available Latar Belakang : Involusi uterus merupakan proses normal pada masa nifas dan dimulai segera setelah plasenta lahir akibat kontraksi otot-otot polos uterus. Stimulus adalah perangsang organism tubuh atau reseptor lain untuk menjadi aktif. Pemberian stimulus Vertebra Cervikal dapat merangsang hipofisis anterior dan posterior untuk mengeluarkan hormon oksitosin. Hormon oksitosin akan memicu kontraksi otot polos pada uterus. Tujuan : Penelitian ini bertujuan untuk manfaat stimulus vertebra cervikalis ke 5-6 dan stimulus otot rectus abdominis terhadap perubahan tfu ibu post partum pervaginam. Metode: Populasi dan sampel dalam penelitian ini adalah ibu postpartum pervaginam di Ruang Nifas RSUD Dr. Soeselo Slawi. penelitian ini menggunakan t-test of relate. Hasil : Dalam uji hipotesis didapatkan t hitung ? t table (10.863 ? 1.980, maka dapat disimpulkan Ho ditolak dan Ha diterima. Kesimpulan : Artinya terdapat manfaat stimulus vertebra cervikalis ke 5-6 dan stimulus otot rectus abdominis terhadap perubahan tinggi fundus uteri ibu postpartum pervaginam.

  9. Distortions of temporal integration and perceived order caused by the interplay between stimulus contrast and duration

    NARCIS (Netherlands)

    Akyürek, Elkan G.; de Jong, Ritske

    2017-01-01

    Stimulus contrast and duration effects on visual temporal integration and order judgment were examined in a unified paradigm. Stimulus onset asynchrony was governed by the duration of the first stimulus in Experiment 1, and by the interstimulus interval in Experiment 2. In Experiment 1, integration

  10. Structural and EPR studies on single-crystal and polycrystalline samples of copper(II) and cobalt(II) complexes with N2S2-based macrocyclic ligands.

    Science.gov (United States)

    Tamayo, Abel; Casabó, Jaume; Escriche, Lluís; González, Pablo; Lodeiro, Carlos; Rizzi, Alberto C; Brondino, Carlos D; Passeggi, M C G; Kivekäs, Raikko; Sillanpää, Reijo

    2007-07-09

    The properties of Cu(II) and Co(II) complexes with oxygen- or nitrogen-containing macrocycles have been extensively studied; however, less attention has been paid to the study of complexes containing sulfur atoms in the first coordination sphere. Herein we present the interaction between these two metal ions and two macrocyclic ligands with N2S2 donor sets. Cu(II) and Co(II) complexes with the pyridine-containing 14-membered macrocycles 3,11-dithia-7,17-diazabicyclo[11.3.1]heptadeca-1(17),13,15-triene (L) and 7-(9-anthracenylmethyl)-3,11-dithia-7,17-diazabicyclo[11.3.1]heptadeca-1(17),13,15-triene (L1) have been synthesized. The X-ray structural analysis of {[Co(ClO4)(H2O)(L)][Co(H2O)2(L)]}(ClO4)3 shows two different metal sites in octahedral coordination. The EPR spectra of powdered samples of this compound are typical of distorted six-coordinated Co(II) ions in a high-spin (S=3/2) configuration, with the ground state being S=1/2 (g1=5.20, g2=3.20, g3=1.95). The EPR spectrum of [Cu(ClO4)(L)](ClO4) was simulated assuming an axial g tensor (g1=g2=2.043, g3=2.145), while that of [Cu(ClO4)(L1)](ClO4) slightly differs from an axial symmetry (g1=2.025, g2=2.060, g3=2.155). These results are compatible with a Cu(II) ion in square-pyramidal coordination with N2S2 as basal ligands. Single-crystal EPR experiment performed on [Cu(ClO4)(L1)](ClO4) allowed determining the eigenvalues of the molecular g tensor associated with the copper site, as well as the two possible orientations for the tensor. On the basis of symmetry arguments, an assignment in which the eigenvectors are nearly along the Cu(II)-ligand bonds is chosen.

  11. Single-Molecule Counting of High-Sensitivity Troponin I in Patients Referred for Diagnostic Angiography: Results From the CASABLANCA (Catheter Sampled Blood Archive in Cardiovascular Diseases) Study.

    Science.gov (United States)

    McCarthy, Cian P; Ibrahim, Nasrien E; Lyass, Asya; Li, Yiwei; Gaggin, Hanna K; Simon, Mandy L; Mukai, Renata; Gandhi, Parul; Kelly, Noreen; Motiwala, Shweta R; van Kimmenade, Roland R J; Massaro, Joseph M; D'Agostino, Ralph B; Januzzi, James L

    2018-03-08

    The meaning of high-sensitivity troponin I (hsTnI) concentrations in patients without acute myocardial infarction (MI) requires clarity. We hypothesized that among patients referred for diagnostic coronary angiography without acute MI, hsTnI concentrations would correlate with prevalent coronary artery disease (CAD) and predict incident cardiovascular events and mortality. We measured hsTnI using a single-molecule counting assay (99th percentile, 6 ng/L) in samples from 991 patients obtained at the time of angiography. Concentrations of hsTnI were assessed relative to the severity of CAD and prognosis during mean follow-up of 3.7 years. Median hsTnI concentration was 4.19 ng/L; 38% of patients had hsTnI concentrations ≥99th percentile. Across increasing hsTnI quartiles, patients had higher prevalence of angiographic CAD; in multivariate models, hsTnI ≥99th percentile independently predicted obstructive CAD (odds ratio: 2.57; P 70% coronary stenosis, hsTnI ≥99th percentile independently predicted incident MI (HR: 1.87; P =0.01), cardiovascular mortality (HR: 2.74; P =0.001), and the composite end point of MI and all-cause death (HR: 2.06; P <0.001). In participants with coronary stenosis <70%, hsTnI ≥99th percentile even more strongly predicted incident MI (HR: 8.41; P <0.001), cardiovascular mortality (HR: 3.60; P =0.03), and the composite end point of MI and all-cause death (HR: 3.62; P <0.001). In a large prospective cohort of patients who were free of prevalent MI and undergoing diagnostic coronary angiography, hsTnI concentrations were associated with higher prevalence of CAD and predicted incident MI, cardiovascular death, and all-cause death. URL: http://www.clinicaltrials.gov. Unique identifier: NCT00842868. © 2018 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley.

  12. Coding in pigeons: Multiple-coding versus single-code/default strategies.

    Science.gov (United States)

    Pinto, Carlos; Machado, Armando

    2015-05-01

    To investigate the coding strategies that pigeons may use in a temporal discrimination tasks, pigeons were trained on a matching-to-sample procedure with three sample durations (2s, 6s and 18s) and two comparisons (red and green hues). One comparison was correct following 2-s samples and the other was correct following both 6-s and 18-s samples. Tests were then run to contrast the predictions of two hypotheses concerning the pigeons' coding strategies, the multiple-coding and the single-code/default. According to the multiple-coding hypothesis, three response rules are acquired, one for each sample. According to the single-code/default hypothesis, only two response rules are acquired, one for the 2-s sample and a "default" rule for any other duration. In retention interval tests, pigeons preferred the "default" key, a result predicted by the single-code/default hypothesis. In no-sample tests, pigeons preferred the key associated with the 2-s sample, a result predicted by multiple-coding. Finally, in generalization tests, when the sample duration equaled 3.5s, the geometric mean of 2s and 6s, pigeons preferred the key associated with the 6-s and 18-s samples, a result predicted by the single-code/default hypothesis. The pattern of results suggests the need for models that take into account multiple sources of stimulus control. © Society for the Experimental Analysis of Behavior.

  13. Amplified Brain Processing of Dentoalveolar Pressure Stimulus in Persistent Dentoalveolar Pain Disorder Patients

    Science.gov (United States)

    Moana-Filho, Estephan J.; Bereiter, David A.; Nixdorf, Donald R.

    2016-01-01

    Aims (1) To determine the brain regions activated by dentoalveolar pressure stimulation in persistent dentoalveolar pain disorder (PDAP) patients, and (2) to compare these activation patterns to those seen in pain-free control subjects. Methods A total of 13 PDAP patients and 13 matched controls completed the study. Clinical pain characteristics and psychosocial data were collected. Dentoalveolar mechanical pain thresholds were determined with a custom-made device over the painful area for patients and were used as the stimulation level during functional magnetic resonance imaging (fMRI) data acquisition. Control subjects received two stimulation levels over matched locations during fMRI scanning: one determined (as above) that evoked equally subjective pain ratings matching those of patients (subjective-pain match) and another nonpainful stimulation level matching the average stimulus intensity provided to patients (stimulus-intensity match). Clinical and psychosocial data were analyzed using independent samples t tests, Mann-Whitney U test, and Spearman rank-order correlation coefficient. fMRI data were analyzed using validated neuroimaging software and tested using a general linear model. Results PDAP patients had greater anxiety (P < .0001) and depression scores (P = .001), more jaw function impairment (P < .0001), and greater social impact (P < .0001) than controls. No significant differences were found for brain activation spatial extent (PDAP × Controls subjective pain: P = .48; PDAP × Controls stimulus intensity: P = .12). Brain activations were significantly increased for PDAP patients compared to control subjects when matched to stimulus intensity in several regions related to the sensory-discriminative and cognitive components of pain perception, including the primary and secondary somatosensory cortices, inferior parietal lobule, insula, premotor cortex, prefrontal cortex, and thalamus. When matched to subjective pain ratings, increased brain

  14. Effects of stimulus-driven synchronization on sensory perception

    Directory of Open Access Journals (Sweden)

    Holden Jameson K

    2007-12-01

    Full Text Available Abstract Background A subject's ability to differentiate the loci of two points on the skin depends on the stimulus-evoked pericolumnar lateral inhibitory interactions which increase the spatial contrast between regions of SI cortex that are activated by stimulus-evoked afferent drive. Nevertheless, there is very little known about the impact that neuronal interactions – such as those evoked by mechanical skin stimuli that project to and coordinate synchronized activity in adjacent and/or near-adjacent cortical columns – could have on sensory information processing. Methods The temporal order judgment (TOJ and temporal discriminative threshold (TDT of 20 healthy adult subjects were assessed both in the absence and presence of concurrent conditions of tactile stimulation. These measures were obtained across a number of paired sites – two unilateral and one bilateral – and several conditions of adapting stimuli were delivered both prior to and concurrently with the TOJ and TDT tasks. The pairs of conditioning stimuli were synchronized and periodic, synchronized and non-periodic, or asynchronous and non-periodic. Results In the absence of any additional stimuli, TOJ and TDT results obtained from the study were comparable across a number of pairs of stimulus sites – unilateral as well as bilateral. In the presence of a 25 Hz conditioning sinusoidal stimulus which was delivered both before, concurrently and after the TOJ task, there was a significant change in the TOJ measured when the two stimuli were located unilaterally on digits 2 and 3. However, in the presence of the same 25 Hz conditioning stimulus, the TOJ obtained when the two stimuli were delivered bilaterally was not impacted. TDT measures were not impacted to the same degree by the concurrent stimuli that were delivered to the unilateral or bilateral stimulus sites. This led to the speculation that the impact that the conditioning stimuli – which were sinusoidal, periodic and

  15. Dissociated sequential activity and stimulus encoding in the dorsomedial striatum during spatial working memory.

    Science.gov (United States)

    Akhlaghpour, Hessameddin; Wiskerke, Joost; Choi, Jung Yoon; Taliaferro, Joshua P; Au, Jennifer; Witten, Ilana B

    2016-09-16

    Several lines of evidence suggest that the striatum has an important role in spatial working memory. The neural dynamics in the striatum have been described in tasks with short delay periods (1-4 s), but remain largely uncharacterized for tasks with longer delay periods. We collected and analyzed single unit recordings from the dorsomedial striatum of rats performing a spatial working memory task with delays up to 10 s. We found that neurons were activated sequentially, with the sequences spanning the entire delay period. Surprisingly, this sequential activity was dissociated from stimulus encoding activity, which was present in the same neurons, but preferentially appeared towards the onset of the delay period. These observations contrast with descriptions of sequential dynamics during similar tasks in other brains areas, and clarify the contribution of the striatum to spatial working memory.

  16. Effects of Spontaneous Locomotion on the Cricket's Walking Response to a Wind Stimulus

    Science.gov (United States)

    Gras, Heribert; Bartels, Anke

    Tethered walking crickets often respond to single wind puffs (50ms duration) directed from 45° left or right to the abdominal cerci with a short running bout of about 300ms, followed by normal locomotion. To test for an effect of the current behavioral state on the running response, we applied wind stimuli when the insect attained a predefined translatorial and/or rotatorial velocity during spontaneous walking. The latency, duration, and velocity profile of the running bout always proved to be constant, representing a reflexlike all-or-nothing reaction, while the probability of this response was low after even brief standing and increased with the forward speed of spontaneous walking at the moment of stimulation. In contrast, the current rotatorial speed did not affect the stimulus response.

  17. Brief-stimulus presentations on multiform tandem schedules

    OpenAIRE

    Reed, Phil

    1994-01-01

    Three experiments examined the influence of a brief stimulus (a light) on the behavior of food-deprived rats whose lever pressing on tandem schedules comprising components of different schedule types resulted in food presentation. In Experiment 1, either a tandem variable-ratio variable-interval or a tandem variable-interval variable-ratio schedule was used. The variable-interval requirement in the tandem variable-ratio variable-interval schedule was yoked to the time taken to complete the va...

  18. Functional imaging of stimulus convergence in amygdalar neurons during Pavlovian fear conditioning.

    Directory of Open Access Journals (Sweden)

    Sabiha K Barot

    2009-07-01

    Full Text Available Associative conditioning is a ubiquitous form of learning throughout the animal kingdom and fear conditioning is one of the most widely researched models for studying its neurobiological basis. Fear conditioning is also considered a model system for understanding phobias and anxiety disorders. A fundamental issue in fear conditioning regards the existence and location of neurons in the brain that receive convergent information about the conditioned stimulus (CS and unconditioned stimulus (US during the acquisition of conditioned fear memory. Convergent activation of neurons is generally viewed as a key event for fear learning, yet there has been almost no direct evidence of this critical event in the mammalian brain.Here, we used Arc cellular compartmental analysis of temporal gene transcription by fluorescence in situ hybridization (catFISH to identify neurons activated during single trial contextual fear conditioning in rats. To conform to temporal requirements of catFISH analysis we used a novel delayed contextual fear conditioning protocol which yields significant single- trial fear conditioning with temporal parameters amenable to catFISH analysis. Analysis yielded clear evidence that a population of BLA neurons receives convergent CS and US information at the time of the learning, that this only occurs when the CS-US arrangement is supportive of the learning, and that this process requires N-methyl-D-aspartate receptor activation. In contrast, CS-US convergence was not observed in dorsal hippocampus.Based on the pattern of Arc activation seen in conditioning and control groups, we propose that a key requirement for CS-US convergence onto BLA neurons is the potentiation of US responding by prior exposure to a novel CS. Our results also support the view that contextual fear memories are encoded in the amygdala and that the role of dorsal hippocampus is to process and transmit contextual CS information.

  19. Fractal gait patterns are retained after entrainment to a fractal stimulus.

    Science.gov (United States)

    Rhea, Christopher K; Kiefer, Adam W; Wittstein, Matthew W; Leonard, Kelsey B; MacPherson, Ryan P; Wright, W Geoffrey; Haran, F Jay

    2014-01-01

    Previous work has shown that fractal patterns in gait can be altered by entraining to a fractal stimulus. However, little is understood about how long those patterns are retained or which factors may influence stronger entrainment or retention. In experiment one, participants walked on a treadmill for 45 continuous minutes, which was separated into three phases. The first 15 minutes (pre-synchronization phase) consisted of walking without a fractal stimulus, the second 15 minutes consisted of walking while entraining to a fractal visual stimulus (synchronization phase), and the last 15 minutes (post-synchronization phase) consisted of walking without the stimulus to determine if the patterns adopted from the stimulus were retained. Fractal gait patterns were strengthened during the synchronization phase and were retained in the post-synchronization phase. In experiment two, similar methods were used to compare a continuous fractal stimulus to a discrete fractal stimulus to determine which stimulus type led to more persistent fractal gait patterns in the synchronization and post-synchronization (i.e., retention) phases. Both stimulus types led to equally persistent patterns in the synchronization phase, but only the discrete fractal stimulus led to retention of the patterns. The results add to the growing body of literature showing that fractal gait patterns can be manipulated in a predictable manner. Further, our results add to the literature by showing that the newly adopted gait patterns are retained for up to 15 minutes after entrainment and showed that a discrete visual stimulus is a better method to influence retention.

  20. Interaction of z component of magnetic field between two samples of GO material in the round rotational single sheet tester (RRSST)

    International Nuclear Information System (INIS)

    Gorican, Viktor; Hamler, Anton; Jesenik, Marko; Stumberger, Bojan; Trlep, Mladen

    2006-01-01

    The magnetic properties of two grain-oriented (GO) samples of the same grade were measured under alternating and rotational magnetic flux conditions. Two samples were measured separately and then together in different arrangement to each other. The interaction of magnetic field between two samples were measured by using a coil, which was placed in between. The results show that the H z component influence measured magnetic properties in the x-y plane

  1. Utility-based early modulation of processing distracting stimulus information.

    Science.gov (United States)

    Wendt, Mike; Luna-Rodriguez, Aquiles; Jacobsen, Thomas

    2014-12-10

    Humans are selective information processors who efficiently prevent goal-inappropriate stimulus information to gain control over their actions. Nonetheless, stimuli, which are both unnecessary for solving a current task and liable to cue an incorrect response (i.e., "distractors"), frequently modulate task performance, even when consistently paired with a physical feature that makes them easily discernible from target stimuli. Current models of cognitive control assume adjustment of the processing of distractor information based on the overall distractor utility (e.g., predictive value regarding the appropriate response, likelihood to elicit conflict with target processing). Although studies on distractor interference have supported the notion of utility-based processing adjustment, previous evidence is inconclusive regarding the specificity of this adjustment for distractor information and the stage(s) of processing affected. To assess the processing of distractors during sensory-perceptual phases we applied EEG recording in a stimulus identification task, involving successive distractor-target presentation, and manipulated the overall distractor utility. Behavioral measures replicated previously found utility modulations of distractor interference. Crucially, distractor-evoked visual potentials (i.e., posterior N1) were more pronounced in high-utility than low-utility conditions. This effect generalized to distractors unrelated to the utility manipulation, providing evidence for item-unspecific adjustment of early distractor processing to the experienced utility of distractor information. Copyright © 2014 the authors 0270-6474/14/3416720-06$15.00/0.

  2. Parietal cortex mediates perceptual Gestalt grouping independent of stimulus size.

    Science.gov (United States)

    Grassi, Pablo R; Zaretskaya, Natalia; Bartels, Andreas

    2016-06-01

    The integration of local moving elements into a unified gestalt percept has previously been linked to the posterior parietal cortex. There are two possible interpretations for the lack of involvement of other occipital regions. The first is that parietal cortex is indeed uniquely functionally specialized to perform grouping. Another possibility is that other visual regions can perform grouping as well, but that the large spatial separation of the local elements used previously exceeded their neurons' receptive field (RF) sizes, preventing their involvement. In this study we distinguished between these two alternatives. We measured whole-brain activity using fMRI in response to a bistable motion illusion that induced mutually exclusive percepts of either an illusory global Gestalt or of local elements. The stimulus was presented in two sizes, a large version known to activate IPS only, and a version sufficiently small to fit into the RFs of mid-level dorsal regions such as V5/MT. We found that none of the separately localized motion regions apart from parietal cortex showed a preference for global Gestalt perception, even for the smaller version of the stimulus. This outcome suggests that grouping-by-motion is mediated by a specialized size-invariant mechanism with parietal cortex as its anatomical substrate. Copyright © 2016 Elsevier Inc. All rights reserved.

  3. Visual stimulus presentation using fiber optics in the MRI scanner.

    Science.gov (United States)

    Huang, Ruey-Song; Sereno, Martin I

    2008-03-30

    Imaging the neural basis of visuomotor actions using fMRI is a topic of increasing interest in the field of cognitive neuroscience. One challenge is to present realistic three-dimensional (3-D) stimuli in the subject's peripersonal space inside the MRI scanner. The stimulus generating apparatus must be compatible with strong magnetic fields and must not interfere with image acquisition. Virtual 3-D stimuli can be generated with a stereo image pair projected onto screens or via binocular goggles. Here, we describe designs and implementations for automatically presenting physical 3-D stimuli (point-light targets) in peripersonal and near-face space using fiber optics in the MRI scanner. The feasibility of fiber-optic based displays was demonstrated in two experiments. The first presented a point-light array along a slanted surface near the body, and the second presented multiple point-light targets around the face. Stimuli were presented using phase-encoded paradigms in both experiments. The results suggest that fiber-optic based displays can be a complementary approach for visual stimulus presentation in the MRI scanner.

  4. Stimulus Novelty Energizes Actions in the Absence of Explicit Reward.

    Directory of Open Access Journals (Sweden)

    Raphael Koster

    Full Text Available Novelty seeking has been tied to impulsive choice and biased value based choice. It has been postulated that novel stimuli should trigger more vigorous approach and exploration. However, it is unclear whether stimulus novelty can enhance simple motor actions in the absence of explicit reward, a necessary condition for energizing approach and exploration in an entirely unfamiliar situation. In this study human subjects were cued to omit or perform actions in form of button presses by novel or familiar images. We found that subjects' motor actions were faster when cued by a novel compared to a familiar image. This facilitation by novelty was strongest when the delay between cue and action was short, consistent with a link between novelty and impulsive choices. The facilitation of reaction times by novelty was correlated across subjects with trait novelty seeking as measured in the Tridimensional Personality Questionnaire. However, this li between high novelty-seeking and action facilitation was driven by trials with a long delay between cue and action. This prolonged time window of energization following novelty could hint at a mechanistic underpinning of enhanced vigour for approach and exploration frequently postulated for novelty seeking humans. In conclusion, we show that stimulus novelty enhances the speed of a cued motor action. We suggest this is likely to reflect an adaptation to changing environments but may also provide a source of maladaptive choice and impulsive behaviour.

  5. Conditioning across the duration of a backward conditioned stimulus.

    Science.gov (United States)

    Romaniuk, C B; Williams, D A

    2000-10-01

    Five conditioned suppression experiments examined the extent to which an appetitively motivated lever-press response can be punished by different components of a backward conditioned stimulus (CS). Using a 0-s unconditioned stimulus (US)-CS interval, Experiments 1 and 2 showed that the initial 3 s of a normally 30-s backward CS served as a more effective punisher than the CS as a whole. Experiment 3 found no such effect if the US-CS interval were 3 s rather than 0 s. Experiments 4A and 4B found that if the US-CS interval were 0 s, the initial part of the backward CS acquired excitatory properties although the CS as a whole passed a summation test for conditioned inhibition. By contrast, the 3-s US-CS interval supported inhibitory conditioning across the whole duration of the backward CS. Taken together, these findings support a modified version of Wagner's sometimes opponent process model, which suggests that different components of a backward CS become either excitatory or inhibitory depending on the components' temporal proximity to the US.

  6. Deconstructing phonological tasks: The contribution of stimulus and response type to the prediction of early decoding skills.

    Science.gov (United States)

    Cunningham, Anna J; Witton, Caroline; Talcott, Joel B; Burgess, Adrian P; Shapiro, Laura R

    2015-10-01

    Phonological tasks are highly predictive of reading development but their complexity obscures the underlying mechanisms driving this association. There are three key components hypothesised to drive the relationship between phonological tasks and reading; (a) the linguistic nature of the stimuli, (b) the phonological complexity of the stimuli, and (c) the production of a verbal response. We isolated the contribution of the stimulus and response components separately through the creation of latent variables to represent specially designed tasks that were matched for procedure. These tasks were administered to 570 6 to 7-year-old children along with standardised tests of regular word and non-word reading. A structural equation model, where tasks were grouped according to stimulus, revealed that the linguistic nature and the phonological complexity of the stimulus predicted unique variance in decoding, over and above matched comparison tasks without these components. An alternative model, grouped according to response mode, showed that the production of a verbal response was a unique predictor of decoding beyond matched tasks without a verbal response. In summary, we found that multiple factors contributed to reading development, supporting multivariate models over those that prioritize single factors. More broadly, we demonstrate the value of combining matched task designs with latent variable modelling to deconstruct the components of complex tasks. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

  7. A Comparison of Herpetofaunal Sampling Effectiveness of Pitfall, Single-ended, and Double-ended Funnel Traps Used with Drift Fences

    Science.gov (United States)

    Cathryn H. Greenberg; Daniel G. Neary; Larry D. Harris

    1994-01-01

    We assessed the relative effectiveness of pitfalls, single-ended, and double-ended funnel traps at 12 replicate sites in sand pine scrub using drift fence arrays. Pitfalls captured fewer species but yielded more individuals of many species and higher average species richness than funnel traps. Pitfalls and funnel traps exhibited differential capture bias probably due...

  8. Characteristics and Sampling Efficiencies of Two Impactor Bioaerosol Samplers: MAS-100(Registered) (Microbial Air Monitoring System) and Single-Stage Andersen Viable Microbial Samplers

    National Research Council Canada - National Science Library

    Hottell, K

    2004-01-01

    .... A petri dish with agar is used as the impaction surface for these samplers. The MAS-l00 is a single-stage impactor that aspirates air through a 400-hole perforated entry plate onto an agar plate at an airflow rate of 100 L/min...

  9. Modelling dose rate to single grains of quartz in well-sorted sand samples: The dispersion arising from the presence of potassium feldspars and implications for single grain OSL dating

    DEFF Research Database (Denmark)

    Guerin, Guillaume; Jain, Mayank; Thomsen, Kristina Jørkov

    2015-01-01

    Single grain OSL has become a widely used approach in Quaternary geochronology. However, the origins of De distributions and the sources of variation in individual dose estimates are still poorly understood. The amount of scatter in these distributions on top of the known uncertainties...... in measurement and analysis is defined by overdispersion and this quantity is generally used for weighting individual De values to calculate a central equivalent dose. In this study, we address the nature and amount of different sources of dispersion in quartz single grain De estimates, by (i) using appropriate...... statistical tools to characterize De populations and (ii) modelling, with a specifically designed GEANT4 code, dose rate distributions arising from the presence of potassium feldspar grains in well-sorted sands. The model uses Monte Carlo simulations of beta emissions and interactions in a random close...

  10. Fixing the stimulus-as-fixed-effect fallacy in task fMRI [version 2; referees: 1 approved, 2 approved with reservations

    Directory of Open Access Journals (Sweden)

    Jacob Westfall

    2017-03-01

    Full Text Available Most functional magnetic resonance imaging (fMRI experiments record the brain’s responses to samples of stimulus materials (e.g., faces or words. Yet the statistical modeling approaches used in fMRI research universally fail to model stimulus variability in a manner that affords population generalization, meaning that researchers’ conclusions technically apply only to the precise stimuli used in each study, and cannot be generalized to new stimuli. A direct consequence of this stimulus-as-fixed-effect fallacy is that the majority of published fMRI studies have likely overstated the strength of the statistical evidence they report. Here we develop a Bayesian mixed model (the random stimulus model; RSM that addresses this problem, and apply it to a range of fMRI datasets. Results demonstrate considerable inflation (50-200% in most of the studied datasets of test statistics obtained from standard “summary statistics”-based approaches relative to the corresponding RSM models. We demonstrate how RSMs can be used to improve parameter estimates, properly control false positive rates, and test novel research hypotheses about stimulus-level variability in human brain responses.

  11. A method for using unmanned aerial vehicles for emergency investigation of single geo-hazards and sample applications of this method

    Science.gov (United States)

    Huang, Haifeng; Long, Jingjing; Yi, Wu; Yi, Qinglin; Zhang, Guodong; Lei, Bangjun

    2017-11-01

    In recent years, unmanned aerial vehicles (UAVs) have become widely used in emergency investigations of major natural hazards over large areas; however, UAVs are less commonly employed to investigate single geo-hazards. Based on a number of successful investigations in the Three Gorges Reservoir area, China, a complete UAV-based method for performing emergency investigations of single geo-hazards is described. First, a customized UAV system that consists of a multi-rotor UAV subsystem, an aerial photography subsystem, a ground control subsystem and a ground surveillance subsystem is described in detail. The implementation process, which includes four steps, i.e., indoor preparation, site investigation, on-site fast processing and application, and indoor comprehensive processing and application, is then elaborated, and two investigation schemes, automatic and manual, that are used in the site investigation step are put forward. Moreover, some key techniques and methods - e.g., the layout and measurement of ground control points (GCPs), route planning, flight control and image collection, and the Structure from Motion (SfM) photogrammetry processing - are explained. Finally, three applications are given. Experience has shown that using UAVs for emergency investigation of single geo-hazards greatly reduces the time, intensity and risks associated with on-site work and provides valuable, high-accuracy, high-resolution information that supports emergency responses.

  12. Optimum time of blood sampling for determination of glomerular filtration rate by single-injection [51Cr]EDTA plasma clearance

    International Nuclear Information System (INIS)

    Broechner-Mortensen, J.; Roedbro, P.

    1976-01-01

    We have investigated the influence on reproducibility of total [ 51 Cr]EDTA plasma clearance (E) of various times and numbers of blood samples in patients with normal (13 patients) and low (14 patients) renal function. The study aims at fixing a clinically useful procedure suitable for all levels of renal function. Six different types of E were evaluated with time periods for blood sampling between 3 and 5 h after tracer injection, and the variation from counting radioactivity, s 1 , was determined as part of the total variation, s 2 . Optimum mean time, t(E), for blood sampling was calculated as a function of E, as the mean time giving the least change in E for a given change in the 'final slope' of the plasma curve. For patients with normal E, s 1 did not contribute significantly to s 2 , and t(E) was about 2h. For patients with low renal function s 1 contributed significantly to s 2 , and t(E) increased steeply with decreasing E. The relative error in s 1 from fixed Etypes was calculated for all levels of renal function. The results indicate that blood sampling individualized according to predicted E values is not necessary. A sufficient precision of E can be achieved for all function levels from three blood samples drawn at 180, 240, and 300 min after injection. (Auth.)

  13. Energy-efficient housing stimulus that pays for itself

    International Nuclear Information System (INIS)

    Nevin, Rick

    2010-01-01

    This paper describes an energy-efficient housing stimulus strategy that can: (1) quickly provide large-scale job creation; (2) reduce home energy bills by 30-50% with associated reductions in emissions and energy assistance spending; (3) stabilize home values and reduce foreclosure inventory; (4) help to eliminate childhood lead poisoning; and (5) implement regulatory reforms that highlight market incentives for cost effective energy efficiency and alternative home energy investments. These benefits, far in excess of costs, can be achieved by combining 'lead-safe window replacement' with other weatherization activities and simple regulatory and market reforms. This strategy can help to coordinate American Recovery and Reinvestment Act funding for energy efficiency, the $75 billion Making Home Affordable plan to reduce foreclosures, and the recently announced partnership between the Departments of Energy (DOE) and Housing and Urban Development (HUD) to streamline weatherization efforts and spur job creation.

  14. Stimulus-dependent suppression of chaos in recurrent neural networks

    International Nuclear Information System (INIS)

    Rajan, Kanaka; Abbott, L. F.; Sompolinsky, Haim

    2010-01-01

    Neuronal activity arises from an interaction between ongoing firing generated spontaneously by neural circuits and responses driven by external stimuli. Using mean-field analysis, we ask how a neural network that intrinsically generates chaotic patterns of activity can remain sensitive to extrinsic input. We find that inputs not only drive network responses, but they also actively suppress ongoing activity, ultimately leading to a phase transition in which chaos is completely eliminated. The critical input intensity at the phase transition is a nonmonotonic function of stimulus frequency, revealing a 'resonant' frequency at which the input is most effective at suppressing chaos even though the power spectrum of the spontaneous activity peaks at zero and falls exponentially. A prediction of our analysis is that the variance of neural responses should be most strongly suppressed at frequencies matching the range over which many sensory systems operate.

  15. Memory and convulsive stimulation: effects of stimulus waveform.

    Science.gov (United States)

    Spanis, C W; Squire, L R

    1981-09-01

    Electrical stimulation with brief pulses can produce a seizure requiring less energy than conventional sine-wave stimulation, and it has been suggested that brief-pulse stimulation might reduce the memory loss associated with electroconvulsive therapy (ECT). The authors evaluated the effects of electroconvulsive shock (ECS) on memory in mice by using various waveforms, current intensities, training-ECS intervals, pulse widths, and stimulus durations. When equated for ability to produce seizures, low-energy, brief-pulse stimulation caused as much amnesia as sine-wave stimulation and sometimes more. In the absence of comparisons of the amnesic effects of brief-pulse and sine-wave stimulation in humans, the use of brief pulses for administering ECT is unwarranted.

  16. Discriminative and reinforcing stimulus properties of music for rats.

    Science.gov (United States)

    Otsuka, Y; Yanagi, J; Watanabe, S

    2009-02-01

    We trained rats to discriminate music by Bach from that by Stravinsky using operant conditioning. The rats successfully learned the discrimination and transferred their discrimination to novel music by the same artists. Then, we trained rats on concurrent-chain schedule in which the terminal links were associated with different music, Bach or Stravinsky. The rats did not show strong preference for either style of music, although one subject showed a preference for Bach and another subject preferred Stravinsky. Finally, we examined the validity of the concurrent-chain procedure as a method of preference measurement with conspecific vocalization evoked by an aversive experience. Most of the rats preferred white noise to the conspecific vocalization. Therefore, music has a discriminative stimulus property but not a clear reinforcing property for rats.

  17. Levels of processing and Eye Movements: A Stimulus driven approach

    DEFF Research Database (Denmark)

    Mulvey, Fiona Bríd

    2014-01-01

    to investigate individual differences in levels of processing within the normal population using existing constructs and tests of cognitive style. Study 4 investigates these stimuli and the eye movements of a clinical group with known interruption to the dorsal stream of processing, and subsequent isolated......The aim of this research is to investigate the explication of levels of attention through eye movement parameters. Previous research from disparate fields have suggested that eye movements are related to cognitive processing, however, the exact nature of the relationship is unclear. Since eye...... movements can be controlled either by bottom up stimulus properties or by top down cognitive control, studies have compared eye movements in real world tasks and searched for indicators of cognitive load or level of attention when task demands increase. Extracting the effects of cognitive processing on eye...

  18. Comparison of mutation patterns in full-genome A/H3N2 influenza sequences obtained directly from clinical samples and the same samples after a single MDCK passage.

    Directory of Open Access Journals (Sweden)

    Hong Kai Lee

    Full Text Available Human influenza viruses can be isolated efficiently from clinical samples using Madin-Darby canine kidney (MDCK cells. However, this process is known to induce mutations in the virus as it adapts to this non-human cell-line. We performed a systematic study to record the pattern of MDCK-induced mutations observed across the whole influenza A/H3N2 genome. Seventy-seven clinical samples collected from 2009-2011 were included in the study. Two full influenza genomes were obtained for each sample: one from virus obtained directly from the clinical sample and one from the matching isolate cultured in MDCK cells. Comparison of the full-genome sequences obtained from each of these sources showed that 42% of the 77 isolates had acquired at least one MDCK-induced mutation. The presence or absence of these mutations was independent of viral load or sample origin (in-patients versus out-patients. Notably, all the five hemagglutinin missense mutations were observed at the hemaggutinin 1 domain only, particularly within or proximal to the receptor binding sites and antigenic site of the virus. Furthermore, 23% of the 77 isolates had undergone a MDCK-induced missense mutation, D151G/N, in the neuraminidase segment. This mutation has been found to be associated with reduced drug sensitivity towards the neuraminidase inhibitors and increased viral receptor binding efficiency to host cells. In contrast, none of the neuraminidase sequences obtained directly from the clinical samples contained the D151G/N mutation, suggesting that this mutation may be an indicator of MDCK culture-induced changes. These D151 mutations can confound the interpretation of the hemagglutination inhibition assay and neuraminidase inhibitor resistance results when these are based on MDCK isolates. Such isolates are currently in routine use in the WHO influenza vaccine and drug-resistance surveillance programs. Potential data interpretation miscalls can therefore be avoided by careful

  19. TMS stimulus-response asymmetry in left- and right-handed individuals.

    Science.gov (United States)

    Daligadu, Julian; Murphy, Bernadette; Brown, Jeff; Rae, Brendan; Yielder, Paul

    2013-02-01

    There have been inconsistencies in the literature regarding asymmetrical neural control and results of experiments using TMS techniques. Therefore, the aim of this study was to further our understanding of the neural relationships that may underlie performance asymmetry with respect to the distal muscles of the hand using a TMS stimulus-response curve technique. Twenty-four male subjects (12 right handed, 12 left handed) participated in a TMS stimulus-response (S-R) curve trial. Focal TMS was applied over the motor cortex to find the optimal position for the first dorsal interossei muscle and to determine rest threshold (RTh). Seven TMS intensities ranging from 90 to 150 % of RTh were delivered in 10 % increments. One single TMS block consisted of 16 stimuli at each intensity. Peak-to-peak amplitudes were measured and the S-R curve generated. In right-handed subjects, the mean difference in slopes between the right and left hand was -0.011 ± 0.03, while the mean difference between hands in left-handed subjects was -0.049 ± 0.08. Left-handed normalized data in right handers displayed a mean of 1.616 ± 1.019 (two-tailed t test p left-handed group showed a significant change in the normalized slope as indicated by a mean of 1.693 ± 0.149 (two-tailed t test p left- and right-handed individuals. However, the results show that the non-dominant motor hemisphere displays a greater amount of excitability than the dominant, which goes against the conventional dogma. This asymmetry indicates that the non-dominant hemisphere may have a higher level of excitation or a lower level of inhibition for both groups of participants.

  20. Acute effects of a vibration-like stimulus during knee extension exercise.

    Science.gov (United States)

    Mileva, Katya N; Naleem, Asif A; Biswas, Santonu K; Marwood, Simon; Bowtell, Joanna L

    2006-07-01

    This study was conducted to test whether a low-frequency vibration-like stimulus (rapid variable resistance) applied during a single session of knee extension exercise would alter muscle performance. Torque, knee joint angle, EMG activity of rectus femoris (RF) and vastus lateralis (VL) muscles, and VL muscle oxygenation status (near-infrared spectroscopy) were recorded during metronome-guided knee extension exercise. Nine healthy adults completed four trials exercising at contraction intensities of 35% (L) or 70% (H) of one-repetition maximum (1RM) in control (no vibration, Vb-) or vibrated condition (superimposed 10-Hz vibration-like stimulus, Vb+). Maximum voluntary contraction and 1RM were tested pre- and postexercise. During 1RM tests, muscle dynamic strength (P=0.02) and power (P=0.05) were significantly higher during vibrated rather than nonvibrated trials, and strength was significantly higher post- than preexercise (P=0.002), except during LVb- trial. Median spectral frequency of VL and RF EMG activity was significantly higher during postexercise than preexercise 1RM test in the vibration trials but unchanged in the control trials (Pvibration superimposition tended to speed muscle deoxygenation rate (P=0.065, 36% effect size) particularly during L trials. Vibration superimposition during knee extension exercise at low contraction intensity enhanced muscle performance. This effect appears to result from adaptation of neural factors such as motor unit excitability (recruitment and firing frequency, conduction velocity of excitation) in response to sensory receptor stimulation. Muscle vibration may increase the training effects derived from light-to-moderate exercise.

  1. Stimulus induced high frequency oscillations are present in neuronal networks on microelectrode arrays.

    Directory of Open Access Journals (Sweden)

    Chadwick M Hales

    2012-05-01

    Full Text Available Pathological high frequency oscillations (250-600Hz are present in the brains of epileptic animals and humans. The etiology of these oscillations and how they contribute to the diseased state remains unclear. This work identifies the presence of microstimulation-evoked high frequency oscillations (250-400Hz in dissociated neuronal networks cultured on microelectrode arrays (MEAs. Oscillations are more apparent with higher stimulus voltages. As with in vivo studies, activity is isolated to a single electrode, however the MEA provides improved spatial resolution with no spread of the oscillation to adjacent electrodes 200µm away. Oscillations develop across 4 weeks in vitro. Oscillations still occur in the presence of tetrodotoxin and synaptic blockers, and they cause no apparent disruption in the ability of oscillation-presenting electrodes to elicit directly evoked action potentials (dAPs or promote the spread of synaptic activity throughout the culture. Chelating calcium with ethylene glycol tetraacetic acid (EGTA causes a temporal prolongation of the oscillation. Finally, carbenoxolone significantly reduces or eliminates the high frequency oscillations. Gap junctions may play a significant role in maintaining the oscillation given the inhibitory effect of carbenoxolone, the propagating effect of reduced calcium conditions and the isolated nature of the activity as demonstrated in previous studies. This is the first demonstration of stimulus evoked high frequency oscillations in dissociated cultures. Unlike current models that rely on complex in vivo recording conditions, this work presents a simple controllable model in neuronal cultures on MEAs to further investigate how the oscillations occur at the molecular level and how they may contribute to the pathophysiology of disease.

  2. Processing bimodal stimulus information under alcohol: is there a risk to being redundant?

    Science.gov (United States)

    Fillmore, Mark T

    2010-10-01

    The impairing effects of alcohol are especially pronounced in environments that involve dividing attention across two or more stimuli. However, studies in cognitive psychology have identified circumstances in which the presentation of multiple stimuli can actually facilitate performance. The "redundant signal effect" (RSE) refers to the observation that individuals respond more quickly when information is presented as redundant, bimodal stimuli (e.g., aurally and visually), rather than as a single stimulus presented to either modality alone. The present study tested the hypothesis that the response facilitation attributed to RSE could reduce the degree to which alcohol slows information processing. Two experiments are reported. Experiment 1 demonstrated the validity of a reaction time model of RSE by showing that adults (N = 15) responded more quickly to redundant, bimodal stimuli (visual + aural) versus either stimuli presented individually. Experiment 2 used the RSE model to test the reaction time performance of 20 adults following three alcohol doses (0.0 g/kg, 0.45 g/kg, and 0.65 g/kg). Results showed that alcohol slowed reaction time in a general dose-dependent manner in all three stimulus conditions with the reaction time (RT) speed-advantage of the redundant signal being maintained, even under the highest dose of alcohol. Evidence for an RT advantage to bimodal stimuli under alcohol challenges the general assumption that alcohol impairment is intensified in multistimulus environments. The current study provides a useful model to investigate how drug effects on behavior might be altered in contexts that involve redundant response signals.

  3. Nicotine as a discriminative stimulus for ethanol use.

    Science.gov (United States)

    Ginsburg, Brett C; Levy, Simon A; Lamb, R J

    2018-01-01

    Abused drugs reinforce behavior; i.e., they increase the probability of the behavior preceding their administration. Abused drugs can also act as discriminative stimuli; i.e., they can set the occasion for responding reinforced by another event. Thus, one abused drug could come to set the occasion for the use of another and this functional relationship may play a role in polysubstance abuse, where common patterns of use could result in this relationship. Here we establish nicotine (0.4mg/kg, ip 5-min pre-session) as a discriminative stimulus for behavior reinforced by ethanol (0.1ml 8% w/v po, versus food) and determine the ability of nicotine (0.02-0.4mg/kg), varenicline (0.1-3.0mg/kg), and ethanol (250 and 500mg/kg) to control responding for ethanol. We compare these results to those from rats where nicotine signaled food was available (and ethanol was not). Nicotine came to function as a discriminative stimulus. Nicotine and varenicline produced dose-dependent increases in responding on the nicotine-appropriate lever while ethanol produced responding on the vehicle-appropriate lever. Whether this responding occurred on the lever that produced ethanol or food access depended on the training condition. These results demonstrate that a drug can come to set the occasion for use of another and suggest that this behavioral mechanism could play an important role in the maintenance of and recovery from polysubstance abuse, depending on the pattern of use. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Evolving microstructure, magnetic properties and phase transition in a mechanically alloyed Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} single sample

    Energy Technology Data Exchange (ETDEWEB)

    Ismail, Ismayadi, E-mail: kayzen@gmail.com [Materials Synthesis and Characterization Laboratory, Institute of Advanced Technology (ITMA), Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Hashim, Mansor; Kanagesan, Samikannu; Ibrahim, Idza Riati; Nazlan, Rodziah; Wan Ab Rahman, Wan Norailiana; Abdullah, Nor Hapishah; Mohd Idris, Fadzidah; Bahmanrokh, Ghazaleh; Shafie, Mohd Shamsul Ezzad [Materials Synthesis and Characterization Laboratory, Institute of Advanced Technology (ITMA), Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Manap, Masni [Physics Department, Faculty of Science, Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia)

    2014-02-15

    We report on an investigation to unravel the dependence of magnetic properties on microstructure while they evolve in parallel under the influence of sintering temperature of a single sample of Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} synthesized via mechanical alloying. A single sample, instead of the normally practiced approach of using multiple samples, was sintered at various sintering temperatures from 500 °C to 1400 °C. The morphology of the samples was studied by means of scanning electron microscopy (SEM) equipped with EDX; density measurement was conducted using the Archimedes principle; and hysteresis measurement was carried out using a B–H hysteresisgraph system. XRD data showed that the first appearance of a single phase was at 800 °C and an amorphous phase was traced at lower sintering temperatures. We correlated the microstructure and the magnetic properties and showed that the important grain-size threshold for the appearance of significant ordered magnetism (mainly ferromagnetism) was about ≥0.3 µm. We found that there were three stages of magnetic phase evolution produced via the sintering process with increasing temperatures. The first stage was dominated by paramagnetic states with some superparamagnetic behavior; the second stage was influenced by moderately ferromagnetic states and some paramagnetic states; and the third stage consisted of strongly ferromagnetic states with negligible paramagnetic states. We found that three factors sensitively influenced the sample's content of ordered magnetism—the ferrite-phase crystallinity degree, the number of grains above the critical grain size and the number of large enough grains for domain wall accommodation. - Highlights: • Grain-size threshold for starting-point appearance of ordered magnetism in single sample Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4}. • The activation energies of grain growth were 16.10 kJ/mol and 137.65 kJ/mol. • Activation energy can be correlated to the first

  5. The perception of regularity in an isochronous stimulus in zebra finches (Taeniopygia guttata) and humans.

    Science.gov (United States)

    van der Aa, Jeroen; Honing, Henkjan; ten Cate, Carel

    2015-06-01

    Perceiving temporal regularity in an auditory stimulus is considered one of the basic features of musicality. Here we examine whether zebra finches can detect regularity in an isochronous stimulus. Using a go/no go paradigm we show that zebra finches are able to distinguish between an isochronous and an irregular stimulus. However, when the tempo of the isochronous stimulus is changed, it is no longer treated as similar to the training stimulus. Training with three isochronous and three irregular stimuli did not result in improvement of the generalization. In contrast, humans, exposed to the same stimuli, readily generalized across tempo changes. Our results suggest that zebra finches distinguish the different stimuli by learning specific local temporal features of each individual stimulus rather than attending to the global structure of the stimuli, i.e., to the temporal regularity. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. Dissociating Stimulus-Set and Response-Set in the Context of Task-Set Switching

    Science.gov (United States)

    Kieffaber, Paul D.; Kruschke, John K.; Cho, Raymond Y.; Walker, Philip M.; Hetrick, William P.

    2014-01-01

    The primary aim of the present research was to determine how stimulus-set and response-set components of task-set contribute to switch costs and conflict processing. Three experiments are described wherein participants completed an explicitly cued task-switching procedure. Experiment 1 established that task switches requiring a reconfiguration of both stimulus- and response-set incurred larger residual switch costs than task switches requiring the reconfiguration of stimulus-set alone. Between-task interference was also drastically reduced for response-set conflict compared with stimulus-set conflict. A second experiment replicated these findings and demonstrated that stimulus- and response-conflict have dissociable effects on the “decision time” and “motor time” components of total response time. Finally, a third experiment replicated Experiment 2 and demonstrated that the stimulus- and response- components of task switching and conflict processing elicit dissociable neural activity as evidence by event-related brain potentials. PMID:22984990

  7. Achilles' heel of a traveling pulse subject to a local external stimulus

    Science.gov (United States)

    Nishi, Kei; Suzuki, Shogo; Kayahara, Katsuhiko; Kuze, Masakazu; Kitahata, Hiroyuki; Nakata, Satoshi; Nishiura, Yasumasa

    2017-06-01

    The response of a traveling pulse to a local external stimulus is considered numerically for a modified three-component Oregonator, which is a model system for the photosensitive Belousov-Zhabotinsky (BZ) reaction. The traveling pulse is traced and constantly stimulated, with the distance between the pulse and the stimulus being kept constant. We are interested in the minimal strength of the spatially localized stimulus in order to eliminate the pulse. The use of a stimulus of small width allows us to detect the point in the pulse most sensitive to the external stimulus, referred to as the "Achilles' heel" of the traveling pulse, at which minimal strength of stimulus causes a collapse of the pulse. Our findings are demonstrated experimentally as well with the photosensitive BZ reaction.

  8. Associative symmetry and stimulus-class formation by pigeons: the role of non-reinforced baseline relations.

    Science.gov (United States)

    Urcuioli, Peter J

    2010-10-01

    Two experiments tested the assumption of Urcuioli's (2008) theory of pigeons' equivalence-class formation that consistent non-reinforcement of certain stimulus combinations in successive matching juxtaposed with consistent reinforcement of other combinations generates stimulus classes containing the elements of the reinforced combinations. In Experiment 1, pigeons were concurrently trained on symbolic (AB) and two identity (AA and BB) successive tasks in which half of all identity trials ended in non-reinforcement but all AB trials were reinforced, contingent upon either responding or not responding to the comparisons. Subsequent symmetry (BA) probe trials showed evidence of symmetry in one of four pigeons. In Experiment 2, pigeons learned three pair-comparison tasks in which left versus right spatial choices were reinforced after the various sample-comparison combinations comprising AB, AA, and BB conditional discriminations. Non-differentially reinforced BA probe trials following acquisition showed some indication of symmetrical choice responding. The overall results contradict the theoretical predictions derived from Urcuioli (2008) and those from Experiment 2 challenge other stimulus-class analyses as well. Copyright © 2010 Elsevier B.V. All rights reserved.

  9. A single-centre experience of the implementation of adrenal vein sampling procedure: the impact on the diagnostic work-up in primary aldosteronism

    NARCIS (Netherlands)

    Kadziela, J.; Prejbisz, A.; Michalowska, I.; Kolodziejczyk-Kruk, S.; Schultze Kool, L.J.; Kabat, M.; Janaszek-Sitkowska, H.; Toutounchi, S.; Galazka, Z.; Ambroziak, U.; Bednarczuk, T.; Ptasinska-Wnuk, D.; Hoffmann, M.; Januszewicz, M.; Januszewicz, A.; Witkowski, A.

    2017-01-01

    BACKGROUND: Primary aldosteronism is one of the most common causes of secondary hypertension. Adrenal vein sampling (AVS) remains a "gold standard" procedure in differentiation between unilateral (adenoma) and bilateral (hyperplasia) disease. AIM: The aim of this study was to present our

  10. Simulation-assisted design of microfluidic sample traps for optimal trapping and culture of non-adherent single cells, tissues, and spheroids.

    Science.gov (United States)

    Rousset, Nassim; Monet, Frédéric; Gervais, Thomas

    2017-03-21

    This work focuses on modelling design and operation of "microfluidic sample traps" (MSTs). MSTs regroup a widely used class of microdevices that incorporate wells, recesses or chambers adjacent to a channel to individually trap, culture and/or release submicroliter 3D tissue samples ranging from simple cell aggregates and spheroids, to ex vivo tissue samples and other submillimetre-scale tissue models. Numerous MST designs employing various trapping mechanisms have been proposed in the literature, spurring the development of 3D tissue models for drug discovery and personalized medicine. Yet, there lacks a general framework to optimize trapping stability, trapping time, shear stress, and sample metabolism. Herein, the effects of hydrodynamics and diffusion-reaction on tissue viability and device operation are investigated using analytical and finite element methods with systematic parametric sweeps over independent design variables chosen to correspond to the four design degrees of freedom. Combining different results, we show that, for a spherical tissue of diameter d < 500 μm, the simplest, closest to optimal trap shape is a cube of dimensions w equal to twice the tissue diameter: w = 2d. Furthermore, to sustain tissues without perfusion, available medium volume per trap needs to be 100× the tissue volume to ensure optimal metabolism for at least 24 hours.

  11. Use of alkaline or enzymatic sample pretreatment prior to characterization of gold nanoparticles in animal tissue by single-particle ICPMS

    DEFF Research Database (Denmark)

    Löschner, Katrin; Brabrand, Myung Suk Jung; Sloth, Jens Jørgen

    2014-01-01

    concentration obtained by conventional ICPMS analysis of acid-digested tissue. The recovery of AuNPs from enzymatically digested tissue, however, was approximately four times lower. Spiking experiments of blank spleen samples with AuNPs showed that the lower recovery was caused by an inferior transport...

  12. Impact of maternal BMI and sampling strategy on the concentration of leptin, insulin, ghrelin and resistin in breast milk across a single feed: a longitudinal cohort study.

    Science.gov (United States)

    Andreas, Nicholas J; Hyde, Matthew J; Herbert, Bronwen R; Jeffries, Suzan; Santhakumaran, Shalini; Mandalia, Sundhiya; Holmes, Elaine; Modi, Neena

    2016-07-07

    We tested the hypothesis that there is a positive association between maternal body mass index (BMI) and the concentration of appetite-regulating hormones leptin, insulin, ghrelin and resistin in breast milk. We also aimed to describe the change in breast milk hormone concentration within each feed, and over time. Mothers were recruited from the postpartum ward at a university hospital in London. Breast milk samples were collected at the participants' homes. We recruited 120 healthy, primiparous, breastfeeding mothers, aged over 18 years. Mothers who smoked, had multiple births or had diabetes were excluded. Foremilk and hindmilk samples were collected from 105 women at 1 week postpartum and 92 women at 3 months postpartum. We recorded maternal and infant anthropometric measurements at each sample collection and measured hormone concentrations using a multiplex assay. The concentration of leptin in foremilk correlated with maternal BMI at the time of sample collection, at 7 days (r=0.31, p=0.02) and 3 months postpartum (r=0.30, p=milk ghrelin and resistin were not correlated with maternal BMI. Ghrelin concentrations at 3 months postpartum were increased in foremilk compared with hindmilk (p=0.01). Concentrations of ghrelin were increased in hindmilk collected at 1  week postpartum compared with samples collected at 3 months postpartum (p=0.03). A trend towards decreased insulin concentrations in hindmilk was noted. Concentrations of leptin and resistin were not seen to alter over a feed. A positive correlation between maternal BMI and foremilk leptin concentration at both time points studied, and foremilk insulin at 3 months postpartum was observed. This may have implications for infant appetite regulation and obesity risk. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

  13. Learning to fear a second-order stimulus following vicarious learning

    OpenAIRE

    Reynolds, G; Field, AP; Askew, C

    2015-01-01

    Vicarious fear learning refers to the acquisition of fear via observation of the fearful responses of others. The present study aims to extend current knowledge by exploring whether second-order vicarious fear learning can be demonstrated in children. That is, whether vicariously learnt fear responses for one stimulus can be elicited in a second stimulus associated with that initial stimulus. Results demonstrated that children’s (5–11 years) fear responses for marsupials and caterpillars incr...

  14. Order of stimulus presentation modulates interference in Stroop matching tasks: a reaction time study

    OpenAIRE

    Caldas, Ariane Leão; David, Isabel de Paula Antunes; Portes, Paula Martins; Portugal, Anna Carolina de Almeida; Machado-Pinheiro, Walter

    2015-01-01

    In the classic Stroop effect, the time spent to name the color of an incongruent stimulus (GREEN in blue) is longer than the time necessary to name the color of a congruent stimulus (BLUE in blue). In the “Stroop matching task”, volunteers are instructed to compare attributes of two stimuli, in which one of them is necessarily a Stroop stimulus. Our aim was to investigate whether the order of stimulus presentation can explain some contradictory results and reveal the imposition of high-order ...

  15. Neural correlates of derived relational responding on tests of stimulus equivalence

    Directory of Open Access Journals (Sweden)

    Cataldo Michael F

    2008-02-01

    Full Text Available Abstract Background An essential component of cognition and language involves the formation of new conditional relations between stimuli based upon prior experiences. Results of investigations on transitive inference (TI highlight a prominent role for the medial temporal lobe in maintaining associative relations among sequentially arranged stimuli (A > B > C > D > E. In this investigation, medial temporal lobe activity was assessed while subjects completed "Stimulus Equivalence" (SE tests that required deriving conditional relations among stimuli within a class (A ≡ B ≡ C. Methods Stimuli consisted of six consonant-vowel-consonant triads divided into two classes (A1, B1, C1; A2, B2, C2. A simultaneous matching-to-sample task and differential reinforcement were employed during pretraining to establish the conditional relations A1:B1 and B1:C1 in class 1 and A2:B2 and B2:C2 in class 2. During functional neuroimaging, recombined stimulus pairs were presented and subjects judged (yes/no whether stimuli were related. SE tests involved presenting three different types of within-class pairs: Symmetrical (B1 A1; C1 B1; B2 A2; C2 B2, and Transitive (A1 C1; A2 C2 and Equivalence (C1 A1; C2 A2 relations separated by a nodal stimulus. Cross-class 'Foils' consisting of unrelated stimuli (e.g., A1 C2 were also presented. Results Relative to cross-class Foils, Transitive and Equivalence relations requiring inferential judgments elicited bilateral activation in the anterior hippocampus while Symmetrical relations elicited activation in the parahippocampus. Relative to each derived relation, Foils generally elicited bilateral activation in the parahippocampus, as well as in frontal and parietal lobe regions. Conclusion Activation observed in the hippocampus to nodal-dependent derived conditional relations (Transitive and Equivalence relations highlights its involvement in maintaining relational structure and flexible memory expression among stimuli within a

  16. A Feasibility Study of Low-Dose Single-Scan Dual-Energy Cone-Beam CT in Many-View Under-Sampling Framework.

    Science.gov (United States)

    Lee, Donghyeon; Lee, Jiseoc; Kim, Hyoyi; Lee, Taewon; Soh, Jeongtae; Park, Miran; Kim, Changhwan; Lee, Yeon Ju; Cho, Seungryong

    2017-12-01

    A single-scan dual-energy low-dose cone-beam CT (CBCT) imaging technique that exploits a multi-slit filter is proposed in this paper. The multi-slit filter installed between the x-ray source and the scanned object is reciprocated during a scan. The x-ray beams through the slits would generate relatively low-energy x-ray projection data, while the filtered beams would make high-energy projection data. An iterative image reconstruction algorithm that uses an adaptive-steepest-descent method to minimize image total-variation under the constraint of data fidelity was applied to reconstructing the image from the low-energy projection data. Since the high-energy projection data suffer from a substantially high noise level due to the beam filtration, we have developed a new algorithm that exploits the joint sparsity between the low- and high-energy CT images for image reconstruction of the high-energy CT image. The proposed image reconstruction algorithm uses a gradient magnitude image (GMI) of the low-energy CT image by regularizing the difference of GMIs of the low- and high-energy CT images to be minimized. The feasibility of the proposed technique has been demonstrated by the use of various phantoms in the experimental CBCT setup. Furthermore, based on the proposed dual-energy imaging, a material differentiation was performed and its potential utility has been shown. The proposed imaging technique produced promising results for its potential application to a low-dose single-scan dual-energy CBCT.

  17. [Detection of Echinococcus granulosus and Echinococcus multilocularis in cyst samples using a novel single tube multiplex real-time polymerase chain reaction].

    Science.gov (United States)

    Can, Hüseyin; İnceboz, Tonay; Caner, Ayşe; Atalay Şahar, Esra; Karakavuk, Muhammet; Döşkaya, Mert; Çelebi, Fehmi; Değirmenci Döşkaya, Aysu; Gülçe İz, Sultan; Gürüz, Yüksel; Korkmaz, Metin

    2016-04-01

    Cystic echinococcosis (CE) and alveolar echinococcosis (AE) caused by Echinococcus granulosus and Echinococcus multilocularis, respectively, are important helminthic diseases worldwide as well as in our country. Epidemiological studies conducted in Turkey showed that the prevalence of CE is 291-585/100.000. It has also been showed that the seroprevalence of AE is 3.5%. For the diagnosis of CE and AE, radiological (ultrasonography, computed tomography, magnetic resonance) and serological methods, in addition to clinical findings, are being used. The definitive diagnosis relies on pathological examination When the hydatid cysts are sterile or does not contain protoscolex, problems may occur during pathological discrimination of E.granulosus and E.multilocularis species. In this study, we aimed to develop a novel multiplex real-time polymerase chain reaction (M-RT-PCR) targeting mitochondrial 12S rRNA gene of E.granulosus and E.multilocularis using Echi S (5'-TTTATGAATATTGTGACCCTGAGAT-3') and Echi A (5'-GGTCTTAACTCAACTCATGGAG-3') primers and three different probes; Anchor Ech (5'-GTTTGCCACCTCGATGTTGACTTAG-fluoroscein-3'), Granulosus (5'-LC640-CTAAGGTTTTGGTGTAGTAATTGATATTTT-phosphate-3') and Multilocularis (5'-LC705-CTGTGATCTTGGTGTAGTAGTTGAGATT-phosphate-3') that will enable the diagnosis of CE and AE in same assay. During M-RTR-PCR, plasmids containing E.granulosus (GenBank: AF297617.1) and E.multilocularis (GenBank: NC_000928.2) mitochondrial 12S rRNA regions were used as positive controls. Cysts samples of patients which were pathologically confirmed to be CE (n: 10) and AE (n: 15) and healthy human DNA samples (n: 25) as negative control as well as DNA samples of 12 different parasites (Taenia saginata, Hymenolepis nana, Trichuris trichiura, Fasciola hepatica, Enterobius vermicularis, Toxoplasma gondii, Pneumocystis jirovecii, Trichomonas vaginalis, Cryptosporidium hominis, Strongyloides stercoralis, Plasmodium falciparum, Plasmodium vivax) were used to develop M

  18. Linking mathematical modeling with human neuroimaging to segregate verbal working memory maintenance processes from stimulus encoding.

    Science.gov (United States)

    McKenna, Benjamin S; Brown, Gregory G; Drummond, Sean P A; Turner, Travis H; Mano, Quintino R

    2013-03-01

    A fundamental dissociation for most working memory (WM) theories involves the separation of sensory-perceptual encoding of stimulus information from the maintenance of this information. The present paper reports tests of this separability hypothesis for visually presented pseudowords at both mathematical and neuroimaging levels of analysis. Levels of analysis were linked by two experimental manipulations-visual degradation and pseudoword length variation-that coupled findings from a mathematical modeling study of WM performed in a separate sample to findings from an event-related functional MRI (fMRI) study reported in the present paper. Results from the mathematical modeling study generated parametric signatures of stimulus encoding and WM rehearsal and displacement. These signatures led to specific predictions about neurophysiological responses to study manipulations in a priori regions of interest (ROI). Results demonstrated predicted dissociations of activation signatures in several ROIs. Significant patterns of brain response mirroring the encode signature were observed only during the task encode interval and only in the visual cortex and posterior fusiform gyrus. In contrast, significant brain response mirroring the rehearsal/displacement signature was observed only in the dorsolateral prefrontal cortex, inferior frontal gyrus, and supramarginal gyrus. Present findings support the separability hypothesis insofar as brain regions that underlie sensory-perceptual processes demonstrated encode signatures whereas brain regions that support WM maintenance demonstrated the rehearsal/displacement signature. These results also provide evidence for the utility of combining mathematical modeling with fMRI to integrate information across cognitive and neural levels of analysis. PsycINFO Database Record (c) 2013 APA, all rights reserved.

  19. Association between a disrupted-in-schizophrenia 1 (DISC1) single nucleotide polymorphism and schizophrenia in a combined Scandinavian case-control sample

    DEFF Research Database (Denmark)

    Saetre, Peter; Agartz, Ingrid; De Franciscis, Alessandra

    2008-01-01

    after correction for multiple testing. However, the minor allele of rs3737597 (frequency 2%) in the 3'-untranslated region (UTR), previously identified as a risk allele in Finnish families, was significantly and consistently associated with the disorder across the three samples, (p-value corrected...... for multiple testing was 0.002). Our results suggest that a relatively uncommon DISC1 mutation, which increases the susceptibility for schizophrenia may be segregating in the Scandinavian population, and support the view that common DISC1 SNP alleles are unlikely to account for a substantial proportion...

  20. Improving balance function using vestibular stochastic resonance: optimizing stimulus characteristics.

    Science.gov (United States)

    Mulavara, Ajitkumar P; Fiedler, Matthew J; Kofman, Igor S; Wood, Scott J; Serrador, Jorge M; Peters, Brian; Cohen, Helen S; Reschke, Millard F; Bloomberg, Jacob J

    2011-04-01

    Stochastic resonance (SR) is a phenomenon whereby the response of a non-linear system to a weak periodic input signal is optimized by the presence of a particular non-zero level of noise. Stochastic resonance using imperceptible stochastic vestibular electrical stimulation, when applied to normal young and elderly subjects, has been shown to significantly improve ocular stabilization reflexes in response to whole-body tilt; improved balance performance during postural disturbances and optimize covariance between the weak input periodic signals introduced via venous blood pressure receptors and the heart rate responses. In our study, 15 subjects stood on a compliant surface with their eyes closed. They were given low-amplitude binaural bipolar stochastic electrical stimulation of the vestibular organs in two frequency ranges of 1-2 and 0-30 Hz over the amplitude range of 0 to ±700 μA. Subjects were instructed to maintain an upright stance during 43-s trials, which consisted of baseline (zero amplitude) and stimulation (non-zero amplitude) periods. Measures of stability of the head and trunk using inertial motion unit sensors attached to these segments and the whole body using a force plate were measured and quantified in the mediolateral plane. Using a multivariate optimization criterion, our results show that the low levels of vestibular stimulation given to the vestibular organs improved balance performance in normal healthy subjects in the range of 5-26% consistent with the stochastic resonance phenomenon. In our study, 8 of 15 and 10 of 15 subjects were responsive for the 1-2- and 0-30-Hz stimulus signals, respectively. The improvement in balance performance did not differ significantly between the stimulations in the two frequency ranges. The amplitude of optimal stimulus for improving balance performance was predominantly in the range of ±100 to ±400 μA. A device based on SR stimulation of the vestibular system might be useful as either a training

  1. Relative versus Absolute Stimulus Control in the Temporal Bisection Task

    Science.gov (United States)

    de Carvalho, Marilia Pinhiero; Machado, Armando

    2012-01-01

    When subjects learn to associate two sample durations with two comparison keys, do they learn to associate the keys with the short and long samples (relational hypothesis), or with the specific sample durations (absolute hypothesis)? We exposed 16 pigeons to an ABA design in which phases A and B corresponded to tasks using samples of 1 s and 4 s,…

  2. Concurrent Validity and Sensitivity to Change of Direct Behavior Rating Single-Item Scales (DBR-SIS) Within an Elementary Sample.

    Science.gov (United States)

    Smith, Rhonda L; Eklund, Katie; Kilgus, Stephen P

    2017-06-12

    The purpose of this study was to evaluate the concurrent validity, sensitivity to change, and teacher acceptability of Direct Behavior Rating single-item scales (DBR-SIS), a brief progress monitoring measure designed to assess student behavioral change in response to intervention. Twenty-four elementary teacher-student dyads implemented a daily report card intervention to promote positive student behavior during prespecified classroom activities. During both baseline and intervention, teachers completed DBR-SIS ratings of 2 target behaviors (i.e., Academic Engagement, Disruptive Behavior) whereas research assistants collected systematic direct observation (SDO) data in relation to the same behaviors. Five change metrics (i.e., absolute change, percent of change from baseline, improvement rate difference, Tau-U, and standardized mean difference; Gresham, 2005) were calculated for both DBR-SIS and SDO data, yielding estimates of the change in student behavior in response to intervention. Mean DBR-SIS scores were predominantly moderately to highly correlated with SDO data within both baseline and intervention, demonstrating evidence of the former's concurrent validity. DBR-SIS change metrics were also significantly correlated with SDO change metrics for both Disruptive Behavior and Academic Engagement, yielding evidence of the former's sensitivity to change. In addition, teacher Usage Rating Profile-Assessment (URP-A) ratings indicated they found DBR-SIS to be acceptable and usable. Implications for practice, study limitations, and areas of future research are discussed. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  3. The potential influence of stimulus overselectivity in AAC: information from eye tracking and behavioral studies of attention with individuals with intellectual disabilities.

    Science.gov (United States)

    Dube, William V; Wilkinson, Krista M

    2014-06-01

    This paper examines the phenomenon of stimulus overselectivity, or overselective attention, as it may impact AAC training and use in individuals with intellectual disabilities. Stimulus overselectivity is defined as an atypical limitation in the number of stimuli or stimulus features within an image that are attended to and subsequently learned. Within AAC, the term stimulus could refer to symbols or line drawings on speech-generating devices, drawings or pictures on low-technology systems, and/or the elements within visual scene displays. In this context, overselective attention may result in unusual or uneven error patterns such as confusion between two symbols that share a single feature, or difficulties with transitioning between different types of hardware. We review some of the ways that overselective attention has been studied behaviorally. We then examine how eye tracking technology allows a glimpse into some of the behavioral characteristics of overselective attention. We describe an intervention approach, differential observing responses, that may reduce or eliminate overselectivity, and we consider this type of intervention as it relates to issues of relevance for AAC.

  4. Control effects of stimulus paradigms on characteristic firings of parkinsonism

    Science.gov (United States)

    Zhang, Honghui; Wang, Qingyun; Chen, Guanrong

    2014-09-01

    Experimental studies have shown that neuron population located in the basal ganglia of parkinsonian primates can exhibit characteristic firings with certain firing rates differing from normal brain activities. Motivated by recent experimental findings, we investigate the effects of various stimulation paradigms on the firing rates of parkinsonism based on the proposed dynamical models. Our results show that the closed-loop deep brain stimulation is superior in ameliorating the firing behaviors of the parkinsonism, and other control strategies have similar effects according to the observation of electrophysiological experiments. In addition, in conformity to physiological experiments, we found that there exists optimal delay of input in the closed-loop GPtrain|M1 paradigm, where more normal behaviors can be obtained. More interestingly, we observed that W-shaped curves of the firing rates always appear as stimulus delay varies. We furthermore verify the robustness of the obtained results by studying three pallidal discharge rates of the parkinsonism based on the conductance-based model, as well as the integrate-and-fire-or-burst model. Finally, we show that short-term plasticity can improve the firing rates and optimize the control effects on parkinsonism. Our conclusions may give more theoretical insight into Parkinson's disease studies.

  5. Dynamic structure of joint-action stimulus-response activity.

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    MaryLauren Malone

    Full Text Available The mere presence of a co-actor can influence an individual's response behavior. For instance, a social Simon effect has been observed when two individuals perform a Go/No-Go response to one of two stimuli in the presence of each other, but not when they perform the same task alone. Such effects are argued to provide evidence that individuals co-represent the task goals and the to-be-performed actions of a co-actor. Motivated by the complex-systems approach, the present study was designed to investigate an alternative hypothesis--that such joint-action effects are due to a dynamical (time-evolving interpersonal coupling that operates to perturb the behavior of socially situated actors. To investigate this possibility, participants performed a standard Go/No-Go Simon task in joint and individual conditions. The dynamic structure of recorded reaction times was examined using fractal statistics and instantaneous cross-correlation. Consistent with our hypothesis that participants responding in a shared space would become behaviorally coupled, the analyses revealed that reaction times in the joint condition displayed decreased fractal structure (indicative of interpersonal perturbation processes modulating ongoing participant behavior compared to the individual condition, and were more correlated across a range of time-scales compared to the reaction times of pseudo-pair controls. Collectively, the findings imply that dynamic processes might underlie social stimulus-response compatibility effects and shape joint cognitive processes in general.

  6. Smoking patterns and stimulus control in intermittent and daily smokers.

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    Saul Shiffman

    Full Text Available Intermittent smokers (ITS - who smoke less than daily - comprise an increasing proportion of adult smokers. Their smoking patterns challenge theoretical models of smoking motivation, which emphasize regular and frequent smoking to maintain nicotine levels and avoid withdrawal, but yet have gone largely unexamined. We characterized smoking patterns among 212 ITS (smoking 4-27 days per month compared to 194 daily smokers (DS; smoking 5-30 cigarettes daily who monitored situational antecedents of smoking using ecological momentary assessment. Subjects recorded each cigarette on an electronic diary, and situational variables were assessed in a random subset (n=21,539 smoking episodes; parallel assessments were obtained by beeping subjects at random when they were not smoking (n=26,930 non-smoking occasions. Compared to DS, ITS' smoking was more strongly associated with being away from home, being in a bar, drinking alcohol, socializing, being with friends and acquaintances, and when others were smoking. Mood had only modest effects in either group. DS' and ITS' smoking were substantially and equally suppressed by smoking restrictions, although ITS more often cited self-imposed restrictions. ITS' smoking was consistently more associated with environmental cues and contexts, especially those associated with positive or "indulgent" smoking situations. Stimulus control may be an important influence in maintaining smoking and making quitting difficult among ITS.

  7. Smoking Patterns and Stimulus Control in Intermittent and Daily Smokers

    Science.gov (United States)

    Shiffman, Saul; Dunbar, Michael S.; Li, Xiaoxue; Scholl, Sarah M.; Tindle, Hilary A.; Anderson, Stewart J.; Ferguson, Stuart G.

    2014-01-01

    Intermittent smokers (ITS) – who smoke less than daily – comprise an increasing proportion of adult smokers. Their smoking patterns challenge theoretical models of smoking motivation, which emphasize regular and frequent smoking to maintain nicotine levels and avoid withdrawal, but yet have gone largely unexamined. We characterized smoking patterns among 212 ITS (smoking 4–27 days per month) compared to 194 daily smokers (DS; smoking 5–30 cigarettes daily) who monitored situational antecedents of smoking using ecological momentary assessment. Subjects recorded each cigarette on an electronic diary, and situational variables were assessed in a random subset (n = 21,539 smoking episodes); parallel assessments were obtained by beeping subjects at random when they were not smoking (n = 26,930 non-smoking occasions). Compared to DS, ITS' smoking was more strongly associated with being away from home, being in a bar, drinking alcohol, socializing, being with friends and acquaintances, and when others were smoking. Mood had only modest effects in either group. DS' and ITS' smoking were substantially and equally suppressed by smoking restrictions, although ITS more often cited self-imposed restrictions. ITS' smoking was consistently more associated with environmental cues and contexts, especially those associated with positive or “indulgent” smoking situations. Stimulus control may be an important influence in maintaining smoking and making quitting difficult among ITS. PMID:24599056

  8. Expectation modulates repetition priming under high stimulus variability

    Science.gov (United States)

    Olkkonen, Maria; Aguirre, Geoffrey K.; Epstein, Russell A.

    2017-01-01

    Neural responses to stimuli are often attenuated by repeated presentation. When observed in blood oxygen level-dependent signals, this attenuation is known as fMRI adaptation (fMRIa) or fMRI repetition suppression. According to a prominent account, fMRIa reflects the fulfillment of perceptual expectations during recognition of repeated items (Summerfield, Trittschuh, Monti, Mesulam, & Egner, 2008). Supporting this idea, expectation has been shown to modulate fMRIa under some circumstances; however, it is not currently known whether expectation similarly modulates recognition performance. To address this lacuna, we measured behavioral and fMRI responses to faces while varying the extent to which each stimulus was informative about its successor. Behavioral priming was greater when repetitions were more likely, suggesting that recognition was facilitated by the expectation than an item would repeat. Notably, this effect was only observed when stimuli were drawn from a broad set of faces including many ethnicities and both genders, but not when stimuli were drawn from a narrower face set, thus making repetitions less informative. Moreover, expectation did not modulate fMRIa in face-selective cortex, contrary to previous studies, although an exploratory analysis indicated that it did so in a medial frontal region. These results support the idea that expectation modulates recognition efficiency, but insofar as behavioral effects of expectation were not accompanied by fMRI effects in visual cortex, they suggest that fMRIa cannot be entirely explained in terms of fulfilled expectations. PMID:28617928

  9. ERP Indices of Stimulus Prediction in Letter Sequences

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    Edith Kaan

    2014-10-01

    Full Text Available Given the current focus on anticipation in perception, action and cognition, including language processing, there is a need for a method to tap into predictive processing in situations in which cue and feedback stimuli are not explicitly marked as such. To this aim, event related potentials (ERPs were obtained while participants viewed alphabetic letter sequences (“A”, “B”, “C”, “D”, “E”, …, in which the letters were highly predictable, and random sequences (“S”, “B”, “A”, “I”, “F”, “M”, …, without feedback. Occasionally, the presentation of a letter in a sequence was delayed by 300 ms. During this delay period, an increased negativity was observed for predictive versus random sequences. In addition, the early positivity following the delay was larger for predictive compared with random sequences. These results suggest that expectation-sensitive ERP modulations can be elicited in anticipation of stimuli that are not explicit targets, rewards, feedback or instructions, and that a delay can strengthen the prediction for a particular stimulus. Applications to language processing will be discussed.

  10. STIMULUS TO SOCIAL PARTICIPATION IN HEALTH COUNCILS through medicine students

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    Káritas Rios Lima

    2010-12-01

    Full Text Available The project “Management Strengthining and Stimulus toSocial Participation in Health Councils in Federal Districtthrough Medicine Students and a Strategic Partnership withHealth Family Program Professionals” was developed fromJune to December 2005 in two stages: Area diagnosis of Arealin Taguatinga-DF and Strategic Planning. The objectivewas to qualify and increase the councilors partici pation onthe Health Council making his action more effective. Severalmethodologies were used in the project stages. The Fast PartakingEstimative, the Health center 5 Room of Situation dataanalyses, and the user satisfaction (assessed though questionnaireswere applied during the area diagnosis. The StrategicPlanning was a result of the data analysis collected on thediagnosis stage when the main problems were detected as wellas propositions for their resolutions were made. The resultsreveled socio-economic and cultural contrast, defi cient basicattention to health, ineffective education, inadequate pavementand sewage disposal system. The project provides the medicinestudents an opportunity to get involved in a reality which is achallenge to the social control of public health care policies.

  11. Accessory stimulus modulates executive function during stepping task.

    Science.gov (United States)

    Watanabe, Tatsunori; Koyama, Soichiro; Tanabe, Shigeo; Nojima, Ippei

    2015-07-01

    When multiple sensory modalities are simultaneously presented, reaction time can be reduced while interference enlarges. The purpose of this research was to examine the effects of task-irrelevant acoustic accessory stimuli simultaneously presented with visual imperative stimuli on executive function during stepping. Executive functions were assessed by analyzing temporal events and errors in the initial weight transfer of the postural responses prior to a step (anticipatory postural adjustment errors). Eleven healthy young adults stepped forward in response to a visual stimulus. We applied a choice reaction time task and the Simon task, which consisted of congruent and incongruent conditions. Accessory stimuli were randomly presented with the visual stimuli. Compared with trials without accessory stimuli, the anticipatory postural adjustment error rates were higher in trials with accessory stimuli in the incongruent condition and the reaction times were shorter in trials with accessory stimuli in all the task conditions. Analyses after division of trials according to whether anticipatory postural adjustment error occurred or not revealed that the reaction times of trials with anticipatory postural adjustment errors were reduced more than those of trials without anticipatory postural adjustment errors in the incongruent condition. These results suggest that accessory stimuli modulate the initial motor programming of stepping by lowering decision threshold and exclusively under spatial incompatibility facilitate automatic response activation. The present findings advance the knowledge of intersensory judgment processes during stepping and may aid in the development of intervention and evaluation tools for individuals at risk of falls. Copyright © 2015 the American Physiological Society.

  12. Using Stimulus Fading without Escape Extinction to Increase Compliance with Toothbrushing in Children with Autism

    Science.gov (United States)

    Bishop, Michele R.; Kenzer, Amy L.; Coffman, Christine M.; Tarbox, Courtney M.; Tarbox, Jonathan; Lanagan, Taira M.

    2013-01-01

    Routine toothbrushing is an essential part of good oral hygiene. This study investigated the use of stimulus fading without escape extinction to increase compliance with toothbrushing with three children with autism spectrum disorder (ASD). A 30-step stimulus fading hierarchy was implemented; gradually increasing the proximity of the toothbrush to…

  13. Exploring the role of stimulus code-response modality compatibility on the spatial Stroop effect.

    Science.gov (United States)

    Liao, Min-Ju; Wang, Shan-Hung

    2015-01-01

    This study investigated the compatibility of stimulus codes and response modalities and how it mediated the spatial Stroop effect. Stimulus code (word, arrow and moving dots), response modality (voice, keypress and mouse movement), directional information (left and right) and physical location (centre, left and right) of the stimulus were manipulated. Participants responded to the directional information of the stimulus. Spatial interference was expected when the stimulus' directional information and physical location were incongruent. Results showed that more compatible pairings for the three response modalities were word-voice, arrow-keypress and arrow-movement. Incongruent spatial location delayed the reaction time for all response modalities with the word, speeded up the vocal and keypress responses with the moving dots, and had no effect with the arrow. Arrow was thus recommended for conveying directional information on interfaces. This study demonstrated that spatial interference was mediated by the stimulus code, response modality and their compatibility. This study manipulated three stimulus codes and three response modalities to examine how stimulus–response compatibility mediated the spatial Stroop effect. Spatial interference appeared with the word and moving dots, but not arrow stimulus, for vocal, keypress and mouse responses. Arrow was therefore recommended to convey directional information on an interface.

  14. Decoupling Stimulus Duration from Brightness in Metacontrast Masking: Data and Models

    Science.gov (United States)

    Di Lollo, Vincent; Muhlenen, Adrian von; Enns, James T.; Bridgeman, Bruce

    2004-01-01

    A brief target that is visible when displayed alone can be rendered invisible by a trailing stimulus (metacontrast masking). It has been difficult to determine the temporal dynamics of masking to date because increments in stimulus duration have been invariably confounded with apparent brightness (Bloch's law). In the research reported here,…

  15. Stimulus probability and motor response in young and old adults: An ERP study.

    NARCIS (Netherlands)

    de Looren de Jong, H.; Kok, A.; van Rooy, J.C.

    1989-01-01

    Investigated effects of responding hand and stimulus probability in 24 young males (aged 18-24 yrs) and 24 old males (aged 67-75 yrs) subjects in a reaction time (RT) task in which both rare and frequent stimuli required a response. The effect of stimulus probability was less pronounced in old Ss

  16. The perception of regularity in an isochronous stimulus in zebra finches (Taeniopygia guttata) and humans

    NARCIS (Netherlands)

    van der Aa, J.; Honing, H.; ten Cate, C.

    2015-01-01

    Perceiving temporal regularity in an auditory stimulus is considered one of the basic features of musicality. Here we examine whether zebra finches can detect regularity in an isochronous stimulus. Using a go/no go paradigm we show that zebra finches are able to distinguish between an isochronous

  17. Unconditioned stimulus revaluation to promote conditioned fear extinction in the memory reconsolidation window.

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    Xiang-Xing Zeng

    Full Text Available The retrieval-extinction paradigm, which disrupts the reconsolidation of fear memories in humans, is a non-invasive technique that can be used to prevent the return of fear in humans. In the present study, unconditioned stimulus revaluation was applied in the retrieval-extinction paradigm to investigate its promotion of conditioned fear extinction in the memory reconsolidation window after participants acquired conditioned fear. This experiment comprised three stages (acquisition, unconditioned stimulus revaluation, retrieval-extinction and three methods for indexing fear (unconditioned stimulus expectancy, skin conductance response, conditioned stimulus pleasure rating. After the acquisition phase, we decreased the intensity of the unconditioned stimulus in one group (devaluation and maintained constant for the other group (control. The results indicated that both groups exhibited similar levels of unconditioned stimulus expectancy, but the devaluation group had significantly smaller skin conductance responses and exhibited a growth in conditioned stimulus + pleasure. Thus, our findings indicate unconditioned stimulus revaluation effectively promoted the extinction of conditioned fear within the memory reconsolidation window.

  18. Anticipation increases tactile stimulus processing in the ipsilateral primary somatosensory cortex

    NARCIS (Netherlands)

    Ede, F.L. van; Lange, F.P. de; Maris, E.G.G.

    2014-01-01

    Stimulus anticipation improves perception. To account for this improvement, we investigated how stimulus processing is altered by anticipation. In contrast to a large body of previous work, we employed a demanding perceptual task and investigated sensory responses that occur beyond early evoked

  19. Evaluation of the Multiple-Stimulus without Replacement Preference Assessment Method Using Activities as Stimuli

    Science.gov (United States)

    Daly, Edward J., III; Wells, Nikki J.; Swanger-Gagne, Michelle S.; Carr, James E.; Kunz, Gina M.; Taylor, Ashley M.

    2009-01-01

    The current study examined the accuracy of the multiple-stimulus without replacement (MSWO) preference assessment for identifying preferred common classroom activities as reinforcers with children with behavioral disorders. The accuracy of predictions from the MSWO regarding high, medium, and low stimulus preference was tested by providing…

  20. Effects of Stimulus Characteristics and Background Music on Foreign Language Vocabulary Learning and Forgetting

    Science.gov (United States)

    de Groot, Annette M. B.

    2006-01-01

    This study examined the effects of three stimulus variables and background music on paired-associate learning of foreign language (FL) vocabulary. The stimulus variables were the frequency and concreteness of the native language (L1) words and the (phonotactical) typicality of the FL words. Sixty-four L1-FL pairs were presented for learning six…

  1. The superior colliculus is sensitive to gestalt-like stimulus configuration in hemispherectomy patients.

    Science.gov (United States)

    Georgy, Loraine; Celeghin, Alessia; Marzi, Carlo A; Tamietto, Marco; Ptito, Alain

    2016-08-01

    Patients with cortical blindness following a lesion to the primary visual cortex (V1) may retain nonconscious visual abilities (blindsight). One intriguing, though largely unexplored question, is whether nonconscious vision in the blind hemifield of hemianopic patients can be sensitive to higher-order perceptual organization, and which V1-independent structure underlies such effect. To answer this question, we tested two rare hemianopic patients who had undergone hemispherectomy, and in whom the only post-chiasmatic visual structure left intact in the same side of the otherwise damaged hemisphere was the superior colliculus (SC). By using a variant of the redundant target effect (RTE), we presented single dots, patterns composed by the same dots organized in quadruple gestalt-like configurations, or patterns of four dots arranged in random configurations, either singly to the intact visual hemifield or bilaterally to both hemifields. As reported in a number of prior studies on blindsight patients, we found that bilateral stimulation yielded faster reaction times (RTs) than single stimulation of the intact field for all conditions (i.e., there was an implicit RTE). In addition to this effect, both patients showed a further speeding up of RTs when the gestalt-like, but not the random shape, quadruple patterns were projected to their blind hemifield during bilateral stimulation. Because other retino-recipient subcortical and cortical structures in the damaged hemisphere are absent, the SC on the lesioned side seems solely responsible for such an effect. The present results provide initial support to the notion that nonconscious vision might be sensitive to perceptual organization and stimulus configuration through the pivotal contribution of the SC, which can enhance the processing of gestalt-like or structured stimuli over meaningless or randomly assembled ones and translate them into facilitatory motor outputs. Copyright © 2016 The Authors. Published by Elsevier

  2. Dependence on stimulus onset asynchrony in apparent motion: evidence for two mechanisms.

    Science.gov (United States)

    Boulton, J C; Baker, C L

    1993-09-01

    The detection of the direction of motion was measured as a function of the spatial and temporal offset for a kinematogram stimulus presented in two-frame apparent motion. The stimulus was made up of Gabor function micro-patterns randomly distributed across the stimulus field. We show that for short stimulus onset asynchronies (SOA) performance can be predicted from the spatio-temporal Fourier power spectrum of the stimulus, whereas for long SOAs the pattern of performance is qualitatively different from such a prediction. The dependence of motion perception on SOA exhibits an abrupt change from one mode of behaviour to the other. These findings are suggestive of the operation of distinct mechanisms, one "quasi-linear" and one "nonlinear", which can be separated by temporal parameters.

  3. Temporal neural mechanisms underlying conscious access to different levels of facial stimulus contents.

    Science.gov (United States)

    Hsu, Shen-Mou; Yang, Yu-Fang

    2018-04-01

    An important issue facing the empirical study of consciousness concerns how the contents of incoming stimuli gain access to conscious processing. According to classic theories, facial stimuli are processed in a hierarchical manner. However, it remains unclear how the brain determines which level of stimulus content is consciously accessible when facing an incoming facial stimulus. Accordingly, with a magnetoencephalography technique, this study aims to investigate the temporal dynamics of the neural mechanism mediating which level of stimulus content is consciously accessible. Participants were instructed to view masked target faces at threshold so that, according to behavioral responses, their perceptual awareness alternated from consciously accessing facial identity in some trials to being able to consciously access facial configuration features but not facial identity in other trials. Conscious access at these two levels of facial contents were associated with a series of differential neural events. Before target presentation, different patterns of phase angle adjustment were observed between the two types of conscious access. This effect was followed by stronger phase clustering for awareness of facial identity immediately during stimulus presentation. After target onset, conscious access to facial identity, as opposed to facial configural features, was able to elicit more robust late positivity. In conclusion, we suggest that the stages of neural events, ranging from prestimulus to stimulus-related activities, may operate in combination to determine which level of stimulus contents is consciously accessed. Conscious access may thus be better construed as comprising various forms that depend on the level of stimulus contents accessed. NEW & NOTEWORTHY The present study investigates how the brain determines which level of stimulus contents is consciously accessible when facing an incoming facial stimulus. Using magnetoencephalography, we show that prestimulus

  4. Comparison of immunofluorescence and enzyme-linked immunosorbent assay and immunoglobulin G avidity techniques for screening of anti: Toxoplasma antibodies among single serum sample pregnant women in Tabriz, Iran

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    Mehrangiz Rajaii

    2015-01-01

    Full Text Available Background: Congenital toxoplasmosis is that pregnant women acquire the infection during gestation; diagnosis of the acute infection during pregnancy is a complex subject of maternal toxoplasmosis. Thus, the presence of immunoglobulin G (IgG and/or IgM Toxoplasma antibodies in a single serum sample drawn during gestation cannot be used to define whether the infection was recently acquired or chronic. Materials and Methods: At this cross-sectional descriptive study, sera of 391 pregnant women examined and compared. They were in an age range of 21-35 years, referred by gynecologists and infectious disease specialists, during March 2012-April 2013. They have referred, 215 (54.98%, 102 (26%, 74 (18.92% in the first, second and third trimesters of gestation, respectively. For each of them, a questionnaire was completed and serum samples were prepared in an equal condition, examined according to the procedures of indirect immunofluorescence (IIF, enzyme-linked immunosorbent assay (ELISA and IgG Avidity techniques. Results: We have found 111 (28.38% seronegative and 280 (71.61% seropositive cases by IIF and 124 (31.70% seronegative, 267 (68.28% seropositive cases by ELISA. The IgG avidity test confirmed 45 (69.23% and 7 (10.76% doubtful cases of IgM test in IIF and ELISA techniques. Conclusions: This study highlights how to manage pregnant women with toxoplasmosis, especially in a single serum sample condition.

  5. CT-guided transgluteal biopsy for systematic sampling of the prostate in patients without rectal access: a 13-year single-center experience

    Energy Technology Data Exchange (ETDEWEB)

    Olson, Michael C.; Atwell, Thomas D.; King, Bernard F.; Welch, Timothy; Goenka, Ajit H. [Mayo Clinic, Department of Radiology, Rochester, MN (United States); Mynderse, Lance A. [Mayo Clinic, Department of Urology, Rochester, MN (United States)

    2017-08-15

    The purpose of our study was to examine the safety and diagnostic utility of transgluteal CT-guided prostate biopsy for prostate sampling in patients without rectal access. Seventy-three biopsies were performed in 65 patients over a 13-year period (2002-2015). Mean prostate-specific antigen (PSA) at biopsy was 7.8 ng/mL (range 0.37-31.5). Electronic medical records were reviewed for procedural details and complications. Mean PSA and number of cores in malignant and benign cohorts were compared with Student's t test. Technical success rate was 97.3% (71/73; mean cores 8, range 3-28). Of these, 43.6% (31/71) yielded malignancy (mean Gleason score 7, range 6-10) and 56.3% (40/71) yielded benign tissue. The only complication was an asymptomatic periprostatic hematoma (1/73; 1.4%). In 14 patients who underwent surgery, Gleason scores were concordant in 71.4% (10/14) and discordant in 28.6% (4/14; Gleason 6 on biopsy but Gleason 7 on surgical specimen). Mean effective radiation dose was 18.5 mSv (median 15.0, range 4.4-86.2). There was no significant difference in either mean PSA (p = 0.06) or number of core specimens (p = 0.33) between malignant and benign cohorts. CT-guided transgluteal prostate biopsy is highly safe and reliable for the detection of prostate cancer in men without rectal access. (orig.)

  6. Single-laboratory validation of a method for the determination of furan in foods by using static headspace sampling and gas chromatography/mass spectrometry.

    Science.gov (United States)

    Nyman, Patricia J; Morehouse, Kim M; McNeal, Timothy P; Perfetti, Gracia A; Diachenko, Gregory W

    2006-01-01

    A headspace gas chromatography/mass spectrometry method was developed and validated in-house for the determination of furan in foods. The method of standard additions with d4-furan as the internal standard was used to quantitate furan. The limit of detection and limit of quantitation (LOQ) values ranged from 0.2 and 0.6 nglg, respectively, in apple juice to 0.9 and 2.9 ng/g, respectively, in peanut butter. Recoveries were obtained at 0.5, 1, 2, and 3 times the LOQ. At 1, 2, and 3 times the LOQ, the recoveries ranged from 89.4 to 108%, and the relative standard deviations ranged from 3.3 to 17.3% for all the matrixes. For apple juice, chicken broth, and infant formula, the averaged coefficients of determination from the linear regression analyses were >0.99 with each food fortified at 0.5, 1, 2, and 3 times the LOQ. The coefficients of determination were >0.99 for green beans and 0.96 for peanut butter with the foods fortified at 1, 2, and 3 times the LOQ. Within-laboratory precision was determined by comparing the amounts of furan found in 18 samples by 2 analysts on different days with different instruments. For most of the foods, the difference between the amounts found by each analyst was method was used to conduct a survey of >300 foods. The furan levels found ranged from none detected to 174 ng/g.

  7. CT-guided transgluteal biopsy for systematic sampling of the prostate in patients without rectal access: a 13-year single-center experience.

    Science.gov (United States)

    Olson, Michael C; Atwell, Thomas D; Mynderse, Lance A; King, Bernard F; Welch, Timothy; Goenka, Ajit H

    2017-08-01

    The purpose of our study was to examine the safety and diagnostic utility of transgluteal CT-guided prostate biopsy for prostate sampling in patients without rectal access. Seventy-three biopsies were performed in 65 patients over a 13-year period (2002-2015). Mean prostate-specific antigen (PSA) at biopsy was 7.8 ng/mL (range 0.37-31.5). Electronic medical records were reviewed for procedural details and complications. Mean PSA and number of cores in malignant and benign cohorts were compared with Student's t test. Technical success rate was 97.3% (71/73; mean cores 8, range 3-28). Of these, 43.6% (31/71) yielded malignancy (mean Gleason score 7, range 6-10) and 56.3% (40/71) yielded benign tissue. The only complication was an asymptomatic periprostatic hematoma (1/73; 1.4%). In 14 patients who underwent surgery, Gleason scores were concordant in 71.4% (10/14) and discordant in 28.6% (4/14; Gleason 6 on biopsy but Gleason 7 on surgical specimen). Mean effective radiation dose was 18.5 mSv (median 15.0, range 4.4-86.2). There was no significant difference in either mean PSA (p = 0.06) or number of core specimens (p = 0.33) between malignant and benign cohorts. CT-guided transgluteal prostate biopsy is highly safe and reliable for the detection of prostate cancer in men without rectal access. • Prostate cancer detection in men without rectal access is challenging. • CT-guided transgluteal prostate biopsy is safe and effective in these patients. • CT-guided biopsy may be particularly effective in diagnosing high-grade prostate cancer. • Unilateral CT-guided biopsy may be effective in patients with focal lesions. • The radiation exposure with this technique is acceptable.

  8. Stimulus-dependent effects on right ear advantage in schizophrenia

    Directory of Open Access Journals (Sweden)

    Smucny J

    2012-09-01

    Full Text Available Jason Smucny,1,3 Korey Wylie,3 Jason Tregellas1–31Neuroscience Program, University of Colorado Anschutz Medical Campus, 2Research Science, Denver VA Medical, Center, 3Department of Psychiatry, University of Colorado Anschutz Medical Campus, Aurora, CO, USABackground: When presented with different sounds in each ear (dichotic listening, healthy subjects typically show a preference for stimuli heard in the right ear, an effect termed "right ear advantage". Previous studies examining right ear advantage in schizophrenia have been inconsistent, showing either decreased or increased advantage relative to comparison subjects. Given evidence for enhanced semantic processing in schizophrenia, some of this inconsistency may be due to the type of stimuli presented (words or syllables. The present study examined right ear advantage in patients and controls using both words and syllables as stimuli.Methods: Right ear advantage was compared between 20 patients with schizophrenia and 17 healthy controls. Two versions of the task were used, ie, a consonant-vowel pairing task and a fused rhymed words task.Results: A significant group × task interaction was observed. Relative to healthy controls, patients showed a greater difference on the syllable-based task compared with the word-based task. The number of distractors marked during the syllable-based task was inversely correlated with score on the Global Assessment of Function Scale.Conclusion: The findings are consistent with a left hemisphere dysfunction in schizophrenia, but also suggest that differences may be stimulus-specific, with a relative sparing of the deficit in the context of word stimuli. Performance may be related to measures of social, occupational, and psychological function.Keywords: schizophrenia, right ear advantage, dichotic, distraction

  9. Millisecond precision temporal encoding of stimulus features during cortically generated gamma oscillations in the rat somatosensory cortex.

    Science.gov (United States)

    Bessaih, Thomas; Higley, Michael J; Contreras, Diego

    2018-02-01

    Rodents explore their immediate environment using their whiskers. Such exploration leads to micromotions, which contain many high-frequency (50-200 Hz) components. High-frequency whisker motion is represented faithfully in the temporal structure of the spike trains of trigeminal neurons. However, the representation of high-frequency sensory inputs in cortex is not fully understood. By combining extracellular and intracellular recordings in the rat somatosensory cortex and thalamus, we show that high-frequency sensory inputs, either sinusoidal or white noise, elicit internally generated gamma (20-60 Hz) band oscillations in cortical networks. Gamma oscillations modulate cortical spike probability while preserving sub-millisecond phase relations with high-frequency sensory inputs. Consequently, our results indicate that millisecond precision stimulus-locked spiking activity and sensory-induced gamma oscillation can constitute independent multiplexed coding schemes at the single-cell level. In the natural environment, tactile exploration often leads to high-frequency vibrations at the level of the sensory organs. Single-unit recordings of cortical neurons have pointed towards either a rate or a temporal code for representing high-frequency tactile signals. In cortical networks, sensory processing results from the interaction between feedforward inputs relayed from the thalamus and internally generated activity. However, how the emergent activity represents high-frequency sensory input is not fully understood. Using multisite single-unit, local field potential and intracellular recordings in the somatosensory cortex and thalamus of lightly sedated male rats, we measured neuronal responses evoked by sinusoidal and band-pass white noise whisker stimulation at frequencies that encompass those observed during texture exploration (50-200 Hz). We found that high-frequency sensory inputs relayed from the thalamus elicit both sub-millisecond stimulus-locked responses and

  10. Decoding semantics across fMRI sessions with different stimulus modalities: a practical MVPA study.

    Science.gov (United States)

    Akama, Hiroyuki; Murphy, Brian; Na, Li; Shimizu, Yumiko; Poesio, Massimo

    2012-01-01

    Both embodied and symbolic accounts of conceptual organization would predict partial sharing and partial differentiation between the neural activations seen for concepts activated via different stimulus modalities. But cross-participant and cross-session variability in BOLD activity patterns makes analyses of such patterns with MVPA methods challenging. Here, we examine the effect of cross-modal and individual variation on the machine learning analysis of fMRI data recorded during a word property generation task. We present the same set of living and non-living concepts (land-mammals, or work tools) to a cohort of Japanese participants in two sessions: the first using auditory presentation of spoken words; the second using visual presentation of words written in Japanese characters. Classification accuracies confirmed that these semantic categories could be detected in single trials, with within-session predictive accuracies of 80-90%. However cross-session prediction (learning from auditory-task data to classify data from the written-word-task, or vice versa) suffered from a performance penalty, achieving 65-75% (still individually significant at p « 0.05). We carried out several follow-on analyses to investigate the reason for this shortfall, concluding that distributional differences in neither time nor space alone could account for it. Rather, combined spatio-temporal patterns of activity need to be identified for successful cross-session learning, and this suggests that feature selection strategies could be modified to take advantage of this.

  11. Decoding Semantics across fMRI sessions with Different Stimulus Modalities: A practical MVPA Study

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    Hiroyuki eAkama

    2012-08-01

    Full Text Available Both embodied and symbolic accounts of conceptual organization would predict partial sharing and partial differentiation between the neural activations seen for concepts activated via different stimulus modalities. But cross-participant and cross-session variability in BOLD activity patterns makes analyses of such patterns with MVPA methods challenging. Here we examine the effect of cross-modal and individual variation on the machine learning analysis of fMRI data recorded during a word property generation task. We present the same set of living and non-living concepts (land-mammals, or work tools to a cohort of Japanese participants in two sessions: the first using auditory presentation of spoken words; the second using visual presentation of words written in Japanese characters. Classification accuracies confirmed that these semantic categories could be detected in single trials, with within-session predictive accuracies of 80-90%. However cross-session prediction (learning from auditory-task data to classify data from the written-word-task, or vice-versa suffered from a performance penalty, achieving 65-75% (still individually significant at p<<0.05. We carried out several follow-on analyses to investigate the reason for this shortfall, concluding that distributional differences in neither time nor space alone could account for it. Rather, combined spatio-temporal patterns of activity need to be identified for successful cross-session learning, and this suggests that feature selection strategies could be modified to take advantage of this.

  12. Neglect Patients Exhibit Egocentric or Allocentric Neglect for the Same Stimulus Contingent upon Task Demands.

    Science.gov (United States)

    Leyland, Louise-Ann; Godwin, Hayward J; Benson, Valerie; Liversedge, Simon P

    2017-05-16

    Hemispatial Neglect (HN) is a failure to allocate attention to a region of space opposite to where damage has occurred in the brain, usually the left side of space. It is widely documented that there are two types of neglect: egocentric neglect (neglect of information falling on the individual's left side) and allocentric neglect (neglect of the left side of each object, regardless of the position of that object in relation to the individual). We set out to address whether neglect presentation could be modified from egocentric to allocentric through manipulating the task demands whilst keeping the physical stimulus constant by measuring the eye movement behaviour of a single group of neglect patients engaged in two different tasks (copying and tracing). Eye movements and behavioural data demonstrated that patients exhibited symptoms consistent with egocentric neglect in one task (tracing), and allocentric neglect in another task (copying), suggesting that task requirements may influence the nature of the neglect symptoms produced by the same individual. Different task demands may be able to explain differential neglect symptoms in some individuals.

  13. Incorporating vehicle mix in stimulus-response car-following models

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    Saidi Siuhi

    2016-06-01

    Full Text Available The objective of this paper is to incorporate vehicle mix in stimulus-response car-following models. Separate models were estimated for acceleration and deceleration responses to account for vehicle mix via both movement state and vehicle type. For each model, three sub-models were developed for different pairs of following vehicles including “automobile following automobile,” “automobile following truck,” and “truck following automobile.” The estimated model parameters were then validated against other data from a similar region and roadway. The results indicated that drivers' behaviors were significantly different among the different pairs of following vehicles. Also the magnitude of the estimated parameters depends on the type of vehicle being driven and/or followed. These results demonstrated the need to use separate models depending on movement state and vehicle type. The differences in parameter estimates confirmed in this paper highlight traffic safety and operational issues of mixed traffic operation on a single lane. The findings of this paper can assist transportation professionals to improve traffic simulation models used to evaluate the impact of different strategies on ameliorate safety and performance of highways. In addition, driver response time lag estimates can be used in roadway design to calculate important design parameters such as stopping sight distance on horizontal and vertical curves for both automobiles and trucks.

  14. Multiplexing stimulus information through rate and temporal codes in primate somatosensory cortex.

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    Michael A Harvey

    Full Text Available Our ability to perceive and discriminate textures relies on the transduction and processing of complex, high-frequency vibrations elicited in the fingertip as it is scanned across a surface. How naturalistic vibrations, and by extension texture, are encoded in the responses of neurons in primary somatosensory cortex (S1 is unknown. Combining single unit recordings in awake macaques and perceptual judgments obtained from human subjects, we show that vibratory amplitude is encoded in the strength of the response evoked in S1 neurons. In contrast, the frequency composition of the vibrations, up to 800 Hz, is not encoded in neuronal firing rates, but rather in the phase-locked responses of a subpopulation of neurons. Moreover, analysis of perceptual judgments suggests that spike timing not only conveys stimulus information but also shapes tactile perception. We conclude that information about the amplitude and frequency of natural vibrations is multiplexed at different time scales in S1, and encoded in the rate and temporal patterning of the response, respectively.

  15. Inference of pain stimulus level from stereotypical behavioral response of C.elegans allows quantification of effects of anesthesia and mutation

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    Leung, Kawai; Mohammadi, Aylia; Ryu, William; Nemenman, Ilya

    In animals, we must infer the pain level from experimental characterization of behavior. This is not trivial since behaviors are very complex and multidimensional. To establish C.elegans as a model for pain research, we propose for the first time a quantitative model that allows inference of a thermal nociceptive stimulus level from the behavior of an individual worm. We apply controlled levels of pain by locally heating worms with an infrared laser and capturing the subsequent behavior. We discover that the behavioral response is a product of stereotypical behavior and a nonlinear function of the strength of stimulus. The same stereotypical behavior is observed in normal, anesthetized and mutated worms. From this result we build a Bayesian model to infer the strength of laser stimulus from the behavior. This model allows us to measure the efficacy of anaesthetization and mutation by comparing the inferred strength of stimulus. Based on the measured nociceptive escape of over 200 worms, our model is able to significantly differentiate normal, anaesthetized and mutated worms with 40 worm samples. This work was partially supported by NSF Grant No. IOS/1208126 and HFSP Grant No. RGY0084/.

  16. In vivo stimulus presentation to the mouse vomeronasal system: Surgery, experiment, setup, and software.

    Science.gov (United States)

    Yoles-Frenkel, Michal; Cohen, Oksana; Bansal, Rohini; Horesh, Noa; Ben-Shaul, Yoram

    2017-06-15

    Achieving controlled stimulus delivery is a major challenge in the physiological analysis of the vomeronasal system (VNS). We provide a comprehensive description of a setup allowing controlled stimulus delivery into the vomeronasal organ (VNO) of anesthetized mice. VNO suction is achieved via electrical stimulation of the sympathetic nerve trunk (SNT) using cuff electrodes, followed by flushing of the nasal cavity. Successful application of this methodology depends on several aspects including the surgical preparation, fabrication of cuff electrodes, experimental setup modifications, and the stimulus delivery and flushing. Here, we describe all these aspects in sufficient detail to allow other researchers to readily adopt it. We also present a custom written MATLAB based software with a graphical user interface that controls all aspects of the actual experiment, including trial sequencing, hardware control, and data logging. The method allows measurement of stimulus evoked sensory responses in brain regions that receive vomeronasal inputs. An experienced investigator can complete the entire surgical procedure within thirty minutes. This is the only approach that allows repeated and controlled stimulus delivery to the intact VNO, employing the natural mode of stimulus uptake. The approach is economical with respect to stimuli, requiring stimulus volumes as low as 1-2μl. This comprehensive description will allow other investigators to adapt this setup to their own experimental needs and can thus promote our physiological understanding of this fascinating chemosensory system. With minor changes it can also be adapted for other rodent species. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. The Effect of Monaural Auditory Stimulus on Hand Selection When Reaching.

    Science.gov (United States)

    Tani, Keisuke; Jono, Yasutomo; Nomura, Yoshifumi; Chujo, Yuta; Hiraoka, Koichi

    2017-07-01

    This study investigated the effect of monaural auditory stimulus on hand selection when reaching. Healthy right-handed participants were asked to reach to a visual target and were free to use either the right or left hand. A visual target appeared at one of 11 positions in the visual field between -25 and 25 degrees of the horizontal visual angle. An auditory stimulus was given either in the left or right ear 100 ms after the presentation of the visual target, or no auditory stimulus was given. An auditory stimulus in the right ear increased right hand selection, and that in the left ear slightly increased left hand selection when reaching to a target around the midline of the visual field. The horizontal visual angle, where the probabilities of right hand selection and left hand selection were equal when reaching, shifted leftward when an auditory stimulus was given in the right ear, but the angle did not shift in either direction when an auditory stimulus was given in the left ear. The right-ear-dominant auditory stimulus effect on hand selection indicates hemispheric asymmetry of cortical activity for hand selection.

  18. Comparing different stimulus configurations for population receptive field mapping in human fMRI

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    Ivan eAlvarez

    2015-02-01

    Full Text Available Population receptive field (pRF mapping is a widely used approach to measuring aggregate human visual receptive field properties by recording non-invasive signals using functional MRI. Despite growing interest, no study to date has systematically investigated the effects of different stimulus configurations on pRF estimates from human visual cortex. Here we compared the effects of three different stimulus configurations on a model-based approach to pRF estimation: size-invariant bars and eccentricity-scaled bars defined in Cartesian coordinates and traveling along the cardinal axes, and a novel simultaneous ‘wedge and ring’ stimulus defined in polar coordinates, systematically covering polar and eccentricity axes. We found that the presence or absence of eccentricity scaling had a significant effect on goodness of fit and pRF size estimates. Further, variability in pRF size estimates was directly influenced by stimulus configuration, particularly for higher visual areas including V5/MT+. Finally, we compared eccentricity estimation between phase-encoded and model-based pRF approaches. We observed a tendency for more peripheral eccentricity estimates using phase-encoded methods, independent of stimulus size. We conclude that both eccentricity scaling and polar rather than Cartesian stimulus configuration are important considerations for optimal experimental design in pRF mapping. While all stimulus configurations produce adequate estimates, simultaneous wedge and ring stimulation produced higher fit reliability, with a significant advantage in reduced acquisition time.

  19. Enhanced stimulus-induced gamma activity in humans during propofol-induced sedation.

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    Neeraj Saxena

    Full Text Available Stimulus-induced gamma oscillations in the 30-80 Hz range have been implicated in a wide number of functions including visual processing, memory and attention. While occipital gamma-band oscillations can be pharmacologically modified in animal preparations, pharmacological modulation of stimulus-induced visual gamma oscillations has yet to be demonstrated in non-invasive human recordings. Here, in fifteen healthy humans volunteers, we probed the effects of the GABAA agonist and sedative propofol on stimulus-related gamma activity recorded with magnetoencephalography, using a simple visual grating stimulus designed to elicit gamma oscillations in the primary visual cortex. During propofol sedation as compared to the normal awake state, a significant 60% increase in stimulus-induced gamma amplitude was seen together with a 94% enhancement of stimulus-induced alpha suppression and a simultaneous reduction in the amplitude of the pattern-onset evoked response. These data demonstrate, that propofol-induced sedation is accompanied by increased stimulus-induced gamma activity providing a potential window into mechanisms of gamma-oscillation generation in humans.

  20. JWH-018 and JWH-073: Δ⁹-tetrahydrocannabinol-like discriminative stimulus effects in monkeys.

    Science.gov (United States)

    Ginsburg, Brett C; Schulze, David R; Hruba, Lenka; McMahon, Lance R

    2012-01-01

    Products containing naphthalen-1-yl-(1-pentylindol-3-yl) methanone (JWH-018) and naphthalen-1-yl-(1-butylindol-3-yl) methanone (JWH-073) are emerging drugs of abuse. Here, the behavioral effects of JWH-018 and JWH-073 were examined in one behavioral assay selective for cannabinoid agonism, rhesus monkeys (n = 4) discriminating Δ⁹-tetrahydrocannabinol (Δ⁹-THC; 0.1 mg/kg i.v.), and another assay sensitive to cannabinoid withdrawal, i.e., monkeys (n = 3) discriminating the cannabinoid antagonist rimonabant (1 mg/kg i.v.) during chronic Δ⁹-THC (1 mg/kg s.c. 12 h) treatment. Δ⁹-THC, JWH-018, and JWH-073 increased drug-lever responding in monkeys discriminating Δ⁹-THC; the ED₅₀ values were 0.044, 0.013, and 0.058 mg/kg, respectively and the duration of action was 4, 2, and 1 h, respectively. Rimonabant (0.32-3.2 mg/kg) produced surmountable antagonism of Δ⁹-THC, JWH-018, and JWH-073. Schild analyses and single-dose apparent affinity estimates yielded apparent pA₂/pK(B) values of 6.65, 6.68, and 6.79 in the presence of Δ⁹-THC, JWH-018, and JWH-073, respectively. In Δ⁹-THC-treated monkeys discriminating rimonabant, the training drug increased responding on the rimonabant lever; the ED₅₀ value of rimonabant was 0.20 mg/kg. Δ⁹-THC (1-10 mg/kg), JWH-018 (0.32-3.2 mg/kg), and JWH-073 (3.2-32 mg/kg) dose-dependently attenuated the rimonabant-discriminative stimulus (i.e., withdrawal). These results suggest that Δ⁹-THC, JWH-018, and JWH-073 act through the same receptors to produce Δ⁹-THC-like subjective effects and attenuate Δ⁹-THC withdrawal. The relatively short duration of action of JWH-018 and JWH-073 might lead to more frequent use, which could strengthen habitual use by increasing the frequency of stimulus-outcome pairings. This coupled with the possible greater efficacy of JWH-018 at cannabinoid 1 receptors could be associated with greater dependence liability than Δ⁹-THC.

  1. Antagonism of a (+)N-allylnormetazocine stimulus by (-)PPAP and several structurally related analogs.

    Science.gov (United States)

    Glennon, R A; Young, R; Herndon, J L

    1993-08-01

    Employing rats trained to discriminate 5 mg/kg of the benzomorphan opioid (+)N-allylnormetazocine [(+)NANM] from vehicle, tests of stimulus generalization and antagonism were conducted to determine the influence of several potential sigma-receptor ligands. It has been previously suggested that the (+)NANM stimulus may involve concurrent action at sigma- and phencyclidine (PCP) receptors. Although the low-affinity sigma-antagonist rimcazole was without stimulus-attenuating effect, three novel sigma-ligands--(-)PPAP, CNS 3018, and CNS 3093 (ID50 doses = 3.2, 6.7, and 4.5 mg/kg, respectively)--antagonized the (+)NANM stimulus in a dose-related fashion. The nonselective serotonergic agent 1-(3-trifluoromethyl)phenylpiperazine (TFMPP) produced partial generalization in (+)NANM-trained animals whereas buspirone, a 5-hydroxytryptamine1A (5-HT1A) agonist, attenuated (to 27% drug-appropriate responding) the (+)NANM stimulus. Because the prototypic 5-HT1A agonist 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) failed to attenuate the (+)NANM stimulus at pharmacologically relevant doses, it seems unlikely that the (+)NANM stimulus involves a 5-HT1A mechanism. TFMPP and buspirone display modest affinity for sigma-receptors and this may account for the present findings with these agents. The present results neither establish a role for sigma involvement in the stimulus properties of (+)NANM nor eliminate a role for PCP receptors. They do, however, demonstrate that sigma-ligands with little to no affinity for PCP receptors are capable of antagonizing the (+)NANM stimulus.

  2. Adaptive stimulus optimization and model-based experiments for sensory systems neuroscience

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    Christopher eDiMattina

    2013-06-01

    Full Text Available In this paper we review several lines of recent work aimed at developing practical methods for adaptive on-line stimulus generation for sensory neurophysiology. We consider various experimental paradigms where on-line stimulus optimization is utilized, including the classical textit{optimal stimulus} paradigm where the goal of experiments is to identify a stimulus which maximizes neural responses, the textit{iso-response} paradigm which finds sets of stimuli giving rise to constant responses, and the textit{system identification} paradigm where the experimental goal is to estimate and possibly compare sensory processing models. We discuss various theoretical and practical aspects of adaptive firing rate optimization, including optimization with stimulus space constraints, firing rate adaptation, and possible network constraints on the optimal stimulus. We consider the problem of system identification, and show how accurate estimation of nonlinear models can be highly dependent on the stimulus set used to probe the network. We suggest that optimizing stimuli for accurate model estimation may make it possible to successfully identify nonlinear models which are otherwise intractable, and summarize several recent studies of this type. Finally, we present a two-stage stimulus design procedure which combines the dual goals of model estimation and model comparison and may be especially useful for system identification experiments where the appropriate model is unknown beforehand. We propose that fast, on-line stimulus optimization enabled by increasing computer power can make it practical to move sensory neuroscience away from a descriptive paradigm and towards a new paradigm of real-time model estimation and comparison.

  3. Conditioned pain modulation is minimally influenced by cognitive evaluation or imagery of the conditioning stimulus

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    Bernaba M

    2014-11-01

    Full Text Available Mario Bernaba, Kevin A Johnson, Jiang-Ti Kong, Sean MackeyStanford Systems Neuroscience and Pain Laboratory, Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University School of Medicine, Stanford, CA, USAPurpose: Conditioned pain modulation (CPM is an experimental approach for probing endogenous analgesia by which one painful stimulus (the conditioning stimulus may inhibit the perceived pain of a subsequent stimulus (the test stimulus. Animal studies suggest that CPM is mediated by a spino–bulbo–spinal loop using objective measures such as neuronal firing. In humans, pain ratings are often used as the end point. Because pain self-reports are subject to cognitive influences, we tested whether cognitive factors would impact on CPM results in healthy humans.Methods: We conducted a within-subject, crossover study of healthy adults to determine the extent to which CPM is affected by 1 threatening and reassuring evaluation and 2 imagery alone of a cold conditioning stimulus. We used a heat stimulus individualized to 5/10 on a visual analog scale as the testing stimulus and computed the magnitude of CPM by subtracting the postconditioning rating from the baseline pain rating of the heat stimulus.Results: We found that although evaluation can increase the pain rating of the conditioning stimulus, it did not significantly alter the magnitude of CPM. We also found that imagery of cold pain alone did not result in statistically significant CPM effect.Conclusion: Our results suggest that CPM is primarily dependent on sensory input, and that the cortical processes of evaluation and imagery have little impact on CPM. These findings lend support for CPM as a useful tool for probing endogenous analgesia through subcortical mechanisms.Keywords: conditioned pain modulation, endogenous analgesia, evaluation, imagery, cold presser test, CHEPS, contact heat-evoked potential stimulator

  4. Missing Mass Approximations for the Partition Function of Stimulus Driven Ising Models

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    Robert eHaslinger

    2013-07-01

    Full Text Available Ising models are routinely used to quantify the second order, functional structure of neural populations. With some recent exceptions, they generally do not include the influence of time varying stimulus drive. Yet if the dynamics of network function are to be understood, time varying stimuli must be taken into account. Inclusion of stimulus drive carries a heavy computational burden because the partition function becomes stimulus dependent and must be separately calculated for all unique stimuli observed. This potentially increases computation time by the length of the data set. Here we present an extremely fast, yet simply implemented, method for approximating the stimulus dependent partition function in minutes or seconds. Noting that the most probable spike patterns (which are few occur in the training data, we sum partition function terms corresponding to those patterns explicitly. We then approximate the sum over the remaining patterns (which are improbable, but many by casting it in terms of the stimulus modulated missing mass (total stimulus dependent probability of all patterns not observed in the training data. We use use a product of conditioned logistic regression models to approximate the stimulus modulated missing mass. This method has complexity of roughly O(LNN_{pat} where is L the data length, N the number of neurons and N_{pat} the number of unique patterns in the data, contrasting with the O(L2^N complexity of alternate methods. Using multiple unit recordings from rat hippocampus, macaque DLPFC and cat Area 18 we demonstrate our method requires orders of magnitude less computation time than Monte Carlo methods and can approximate the stimulus driven partition function more accurately than either Monte Carlo methods or deterministic approximations. This advance allows stimuli to be easily included in Ising models making them suitable for studying population based stimulus encoding.

  5. Occipitoparietal contributions to recognition memory: stimulus encoding prompted by verbal instructions and operant contingencies

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    Schlund Michael W

    2007-08-01

    Full Text Available Abstract Background Many human neuroimaging investigations on recognition memory employ verbal instructions to direct subject's attention to a stimulus attribute. But do the same or a similar neurophysiological process occur during nonverbal experiences, such as those involving contingency-shaped responses? Establishing the spatially distributed neural network underlying recognition memory for instructed stimuli and operant, contingency-shaped (i.e., discriminative stimuli would extend the generality of contemporary domain-general views of recognition memory and clarify the involvement of declarative memory processes in human operant behavior. Methods Fifteen healthy adults received equivalent amounts of exposure to three different stimulus sets prior to neuroimaging. Encoding of one stimulus set was prompted using instructions that emphasized memorizing stimuli (Instructed. In contrast, encoding of two additional stimulus sets was prompted using a GO/NO-GO operant task, in which contingencies shaped appropriate GO and NO-GO responding. During BOLD functional MRI, subjects completed two recognition tasks. One required passive viewing of stimuli. The second task required recognizing whether a presented stimulus was a GO/NO-GO stimulus, an Instructed stimulus, or novel (NEW stimulus. Retrieval success related to recognition memory was isolated by contrasting activation from each stimulus set to a novel stimulus (i.e., an OLD > NEW contrast. To explore differences potentially related to source memory, separate contrasts were performed between stimulus sets. Results No regions reached supralevel thresholds during the passive viewing task. However, a relatively similar set of regions was activated during active recognition regardless of the methods and included dorsolateral and ventrolateral prefrontal cortex, right inferior and posterior parietal regions and the occipitoparietal region, precuneus, lingual, fusiform gyri and cerebellum. Results also

  6. Peri-threshold encoding of stimulus frequency and intensity in the M100 latency.

    Science.gov (United States)

    Stufflebeam, S M; Poeppel, D; Rowley, H A; Roberts, T P

    1998-01-05

    Recent work has suggested that, in addition to spatial tonotopy, pitch and timbre information may be encoded in the temporal activity of the auditory cortex. Specifically, the post-stimulus latency of the maximal cortical evoked neuromagnetic field (M100 or N1m) is a function of stimulus frequency. We investigated the additional effect of varying the stimulus intensity on the M100 response. A 37-channel biomagnetometer recorded neuromagnetic fields over the temporal lobe of healthy volunteers in response to monaurally presented tones. The frequency dependence of the M100 latency remained remarkably invariant even at low stimulus intensity. Thus, for peri-threshold stimuli, frequency information appears encoded in the temporal form of the evoked response.

  7. Relationship between Critical Flicker Fusion (CFF) Thresholds and Personality under Three Auditory Stimulus Conditions.

    Science.gov (United States)

    Ali, M. R.; Amir, T.

    1988-01-01

    Investigated relationship between critical flicker fusion (CFF) thresholds and five personality characteristics (alienation; social nonconformity; discomfort, expression, and defensiveness) under three auditory stimulus conditions (quiet, noise, meaningful verbal stimuli). Results from 60 college students revealed that auditory stimulation and…

  8. Dyslexic adults can learn from repeated stimulus presentation but have difficulties in excluding external noise.

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    Rachel L Beattie

    Full Text Available We examined whether the characteristic impairments of dyslexia are due to a deficit in excluding external noise or a deficit in taking advantage of repeated stimulus presentation. We compared non-impaired adults and adults with poor reading performance on a visual letter detection task that varied two aspects: the presence or absence of background visual noise, and a small or large stimulus set. There was no interaction between group and stimulus set size, indicating that the poor readers took advantage of repeated stimulus presentation as well as the non-impaired readers. The poor readers had higher thresholds than non-impaired readers in the presence of high external noise, but not in the absence of external noise. The results support the hypothesis that an external noise exclusion deficit, not a perceptual anchoring deficit, impairs reading for adults.

  9. Encoding efficiency of suprathreshold stochastic resonance on stimulus-specific information

    International Nuclear Information System (INIS)

    Duan, Fabing; Chapeau-Blondeau, François; Abbott, Derek

    2016-01-01

    In this paper, we evaluate the encoding efficiency of suprathreshold stochastic resonance (SSR) based on a local information-theoretic measure of stimulus-specific information (SSI), which is the average specific information of responses associated with a particular stimulus. The theoretical and numerical analyses of SSIs reveal that noise can improve neuronal coding efficiency for a large population of neurons, which leads to produce increased information-rich responses. The SSI measure, in contrast to the global measure of average mutual information, can characterize the noise benefits in finer detail for describing the enhancement of neuronal encoding efficiency of a particular stimulus, which may be of general utility in the design and implementation of a SSR coding scheme. - Highlights: • Evaluating the noise-enhanced encoding efficiency via stimulus-specific information. • New form of stochastic resonance based on the measure of encoding efficiency. • Analyzing neural encoding schemes from suprathreshold stochastic resonance detailedly.

  10. Neuronal representations of stimulus associations develop in the temporal lobe during learning

    OpenAIRE

    Messinger, Adam; Squire, Larry R.; Zola, Stuart M.; Albright, Thomas D.

    2001-01-01

    Visual stimuli that are frequently seen together become associated in long-term memory, such that the sight of one stimulus readily brings to mind the thought or image of the other. It has been hypothesized that acquisition of such long-term associative memories proceeds via the strengthening of connections between neurons representing the associated stimuli, such that a neuron initially responding only to one stimulus of an associated pair eventually comes to respond to both. Consistent with...

  11. Pre-stimulus alpha oscillations over somatosensory cortex predict tactile misperceptions.

    Science.gov (United States)

    Craddock, Matt; Poliakoff, Ellen; El-Deredy, Wael; Klepousniotou, Ekaterini; Lloyd, Donna M

    2017-02-01

    Fluctuations of pre-stimulus oscillatory activity in the somatosensory alpha band (8-14Hz) observed using human EEG and MEG have been shown to influence the detection of supra- and peri-threshold somatosensory stimuli. However, some reports of touch occur even without a stimulus. We investigated the possibility that pre-stimulus alpha oscillations might also influence these false reports of touch - known as tactile misperceptions. We recorded EEG while participants performed the Somatic Signal Detection Task (SSDT), in which participants must detect brief, peri-threshold somatosensory targets. We found that pre-stimulus oscillatory power in the somatosensory alpha range exhibited a negative linear relationship with reporting of touch at electrode clusters over both contralateral and ipsilateral somatosensory regions. As pre-stimulus alpha power increased, the probability of reporting a touch declined; as it decreased, the probability of reporting a touch increased. This relationship was stronger on trials without a somatosensory stimulus than on trials with a somatosensory stimulus, although was present for both trial types. Spatio-temporal cluster-based permutation analysis also found that pre-stimulus alpha was lower on trials when touch was reported - irrespective of whether it was present - over contralateral and ipsilateral somatosensory cortices, as well as left frontocentral areas. We argue that alpha power may reflect changes in response criterion rather than sensitivity alone. Low alpha power relates to a low barrier to reporting a touch even when one is not present, while high alpha power is linked to less frequent reporting of touch overall. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Electrophysiological correlates of changes in reaction time based on stimulus intensity.

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    Bimal Lakhani

    Full Text Available Although reaction time is commonly used as an indicator of central nervous system integrity, little is currently understood about the mechanisms that determine processing time. In the current study, we are interested in determining the differences in electrophysiological events associated with significant changes in reaction time that could be elicited by changes in stimulus intensity. The primary objective is to assess the effect of increasing stimulus intensity on the latency and amplitude of afferent inputs to the somatosensory cortex, and their relation to reaction time.Median nerve stimulation was applied to the non-dominant hand of 12 healthy young adults at two different stimulus intensities (HIGH & LOW. Participants were asked to either press a button as fast as possible with their dominant hand or remain quiet following the stimulus. Electroencephalography was used to measure somatosensory evoked potentials (SEPs and event related potentials (ERPs. Electromyography from the flexor digitorum superficialis of the button-pressing hand was used to assess reaction time. Response time was the time of button press.Reaction time and response time were significantly shorter following the HIGH intensity stimulus compared to the LOW intensity stimulus. There were no differences in SEP (N20 & P24 peak latencies and peak-to-peak amplitude for the two stimulus intensities. ERPs, locked to response time, demonstrated a significantly larger pre-movement negativity to positivity following the HIGH intensity stimulus over the Cz electrode.This work demonstrates that rapid reaction times are not attributable to the latency of afferent processing from the stimulated site to the somatosensory cortex, and those latency reductions occur further along the sensorimotor transformation pathway. Evidence from ERPs indicates that frontal planning areas such as the supplementary motor area may play a role in transforming the elevated sensory volley from the

  13. The modulation of simple reaction time by the spatial probability of a visual stimulus

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    Carreiro L.R.R.

    2003-01-01

    Full Text Available Simple reaction time (SRT in response to visual stimuli can be influenced by many stimulus features. The speed and accuracy with which observers respond to a visual stimulus may be improved by prior knowledge about the stimulus location, which can be obtained by manipulating the spatial probability of the stimulus. However, when higher spatial probability is achieved by holding constant the stimulus location throughout successive trials, the resulting improvement in performance can also be due to local sensory facilitation caused by the recurrent spatial location of a visual target (position priming. The main objective of the present investigation was to quantitatively evaluate the modulation of SRT by the spatial probability structure of a visual stimulus. In two experiments the volunteers had to respond as quickly as possible to the visual target presented on a computer screen by pressing an optic key with the index finger of the dominant hand. Experiment 1 (N = 14 investigated how SRT changed as a function of both the different levels of spatial probability and the subject's explicit knowledge about the precise probability structure of visual stimulation. We found a gradual decrease in SRT with increasing spatial probability of a visual target regardless of the observer's previous knowledge concerning the spatial probability of the stimulus. Error rates, below 2%, were independent of the spatial probability structure of the visual stimulus, suggesting the absence of a speed-accuracy trade-off. Experiment 2 (N = 12 examined whether changes in SRT in response to a spatially recurrent visual target might be accounted for simply by sensory and temporally local facilitation. The findings indicated that the decrease in SRT brought about by a spatially recurrent target was associated with its spatial predictability, and could not be accounted for solely in terms of sensory priming.

  14. Low stimulus environments: reducing noise levels in continuing care.

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    Brown, Juliette; Fawzi, Waleed; Shah, Amar; Joyce, Margaret; Holt, Genevieve; McCarthy, Cathy; Stevenson, Carmel; Marange, Rosca; Shakes, Joy; Solomon-Ayeh, Kwesi

    2016-01-01

    In the low stimulus environment project, we aimed to reduce the levels of intrusive background noise on an older adult mental health ward, combining a very straightforward measure on decibel levels with a downstream measure of reduced distress and agitation as expressed in incidents of violence. This project on reducing background noise levels on older adult wards stemmed from work the team had done on reducing levels of violence and aggression. We approached the problem using quality improvement methods. Reducing harm to patients and staff is a strategic aim of our Trust and in our efforts we were supported by the Trust's extensive programme of quality improvement, including training and support provided by the Institute for Healthcare Improvement and the trust's own Quality Improvement team. Prior to the project we were running a weekly multi-disciplinary quality improvement group on the ward. We established from this a sub-group to address the specific problem of noise levels and invited carers of people with dementia on our ward to the group. The project was led by nursing staff. We used a noise meter app readily downloadable from the internet to monitor background noise levels on the ward and establish a baseline measure. As a group we used a driver diagram to identify an overall aim and a clear understanding of the major factors that would drive improvements. We also used a staff and carer survey to identify further areas to work on. Change ideas that came from staff and carers included the use of the noise meter to track and report back on noise levels, the use of posters to remind staff about noise levels, the introduction of a visual indication of current noise levels (the Yacker Tracker), the addition of relaxing background music, and adaptations to furniture and environment. We tested many of these over the course of nine months in 2015, using the iterative learning gained from multiple PDSA cycles. The specific aim was a decrease from above 60dB to

  15. 3D imaging using X-Ray tomography and SEM combined FIB to study non isothermal creep damage of (111) oriented samples of γ / γ ′ nickel base single crystal superalloy MC2

    KAUST Repository

    Jouiad, Mustapha

    2012-01-01

    An unprecedented investigation consisting of the association of X-Ray tomography and Scanning Electron Microscopy combined with Focus Ion Beam (SEM-FIB) is conducted to perform a 3D reconstruction imaging. These techniques are applied to study the non-isothermal creep behavior of close (111) oriented samples of MC2 nickel base superalloys single crystal. The issue here is to develop a strategy to come out with the 3D rafting of γ\\' particles and its interaction whether with dislocation structures or/and with the preexisting voids. This characterization is uncommonly performed away from the conventional studied orientation [001] in order to feed the viscoplastic modeling leading to its improvement by taking into account the crystal anisotropy. The creep tests were performed at two different conditions: classical isothermal tests at 1050°C under 140 MPa and a non isothermal creep test consisting of one overheating at 1200°C and 30 seconds dwell time during the isothermal creep life. The X-Ray tomography shows a great deformation heterogeneity that is pronounced for the non-isothermal tested samples. This deformation localization seems to be linked to the preexisting voids. Nevertheless, for both tested samples, the voids coalescence is the precursor of the observed damage leading to failure. SEM-FIB investigation by means of slice and view technique gives 3D views of the rafted γ\\' particles and shows that γ corridors evolution seems to be the main creep rate controlling parameter. © 2012 Trans Tech Publications, Switzerland.

  16. Venous Sampling

    Science.gov (United States)

    ... Physician Resources Professions Site Index A-Z Venous sampling Venous sampling is a diagnostic procedure that uses ... the limitations of venous sampling? What is venous sampling? Venous sampling is a diagnostic procedure that involves ...

  17. Identifying controlling variables for math computation fluency through experimental analysis: the interaction of stimulus control and reinforcing consequences.

    Science.gov (United States)

    Hofstadter-Duke, Kristi L; Daly, Edward J

    2015-03-01

    This study investigated a method for conducting experimental analyses of academic responding. In the experimental analyses, academic responding (math computation), rather than problem behavior, was reinforced across conditions. Two separate experimental analyses (one with fluent math computation problems and one with non-fluent math computation problems) were conducted with three elementary school children using identical contingencies while math computation rate was measured. Results indicate that the experimental analysis with non-fluent problems produced undifferentiated responding across participants; however, differentiated responding was achieved for all participants in the experimental analysis with fluent problems. A subsequent comparison of the single-most effective condition from the experimental analyses replicated the findings with novel computation problems. Results are discussed in terms of the critical role of stimulus control in identifying controlling consequences for academic deficits, and recommendations for future research refining and extending experimental analysis to academic responding are made. © The Author(s) 2014.

  18. [Stimulus set and response set in task switching: a comparison using ERP].

    Science.gov (United States)

    Umebayashi, Kaoru; Okita, Tsunetaka

    2008-12-01

    Event-related potential (ERP) and reaction time (RT) were recorded to investigate the time course of processes involved in set switching. The cued set-switching paradigm required participants to switch stimulus task sets between male and female face-images memorized as targets prior to a trial block and response task sets between two stimulus-response mappings for each stimulus task. Replicating previous findings, an RT switch-cost was found when compared with set-repeat trials. The RT was also prolonged for a stimulus task requirement of memory comparison with two-face targets rather than one face. A similar prolongation with memory comparison was observed in P3b latency, which showed no switch effect. The switch effect was observed for the onset latency of stimulus-locked lateralized readiness potential (LRP), measured as an index of commencement of motor processes after response selection. The response-locked LRP indicated that the final process of motor execution itself was not modified by set switching. The processes producing the stimulus-locked LRP switch cost, associated with response task set, were discussed in terms of two hypotheses, exogenous reconfiguration and carryover.

  19. Effects of Stimulus Duration on Event-Related Potentials Recorded From Cochlear-Implant Users.

    Science.gov (United States)

    Presacco, Alessandro; Innes-Brown, Hamish; Goupell, Matthew J; Anderson, Samira

    Several studies have investigated the feasibility of using electrophysiology as an objective tool to efficiently map cochlear implants. A pervasive problem when measuring event-related potentials is the need to remove the direct-current (DC) artifact produced by the cochlear implant. Here, we describe how DC artifact removal can corrupt the response waveform and how the appropriate choice of stimulus duration may minimize this corruption. Event-related potentials were recorded to a synthesized vowel /a/ with a 170- or 400-ms duration. The P2 response, which occurs between 150 and 250 ms, was corrupted by the DC artifact removal algorithm for a 170-ms stimulus duration but was relatively uncorrupted for a 400-ms stimulus duration. To avoid response waveform corruption from DC artifact removal, one should choose a stimulus duration such that the offset of the stimulus does not temporally coincide with the specific peak of interest. While our data have been analyzed with only one specific algorithm, we argue that the length of the stimulus may be a critical factor for any DC artifact removal algorithm.

  20. Mechanisms underlying effects of approach-avoidance training on stimulus evaluation.

    Science.gov (United States)

    Van Dessel, Pieter; Eder, Andreas B; Hughes, Sean

    2018-04-12

    Over the past decade an increasing number of studies across a range of domains have shown that the repeated performance of approach and avoidance (AA) actions in response to a stimulus leads to changes in the evaluation of that stimulus. The dominant (motivational-systems) account in this area claims that these effects are caused by a rewiring of mental associations between stimulus representations and AA systems that evolved to regulate distances to positive and negative stimuli. In contrast, two recently forwarded alternative accounts postulate that AA effects are caused by inferences about the valence of actions and stimuli (inferential account) or a transfer of valenced action codes to stimulus representations (common-coding account). Across four experiments we set out to test these three competing accounts against each other. Experiments 1-3 illustrate that changes in stimulus evaluations can occur when people perform valenced actions that bear no relation to a distance regulation, such as moving a manikin upward or downward. The observed evaluative effects were dependent on the evaluative implication of the instructed movement goal rather than whether the action implied a movement toward or away from the stimuli. These results could not be explained with a rewiring of associations to motivational systems. Experiment 4 showed that changes in stimulus evaluations occurred after participants passively observed approach-avoidance movements, supporting an explanation in terms of cognitive inferences. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

  1. Learning to fear a second-order stimulus following vicarious learning.

    Science.gov (United States)

    Reynolds, Gemma; Field, Andy P; Askew, Chris

    2017-04-01

    Vicarious fear learning refers to the acquisition of fear via observation of the fearful responses of others. The present study aims to extend current knowledge by exploring whether second-order vicarious fear learning can be demonstrated in children. That is, whether vicariously learnt fear responses for one stimulus can be elicited in a second stimulus associated with that initial stimulus. Results demonstrated that children's (5-11 years) fear responses for marsupials and caterpillars increased when they were seen with fearful faces compared to no faces. Additionally, the results indicated a second-order effect in which fear-related learning occurred for other animals seen together with the fear-paired animal, even though the animals were never observed with fearful faces themselves. Overall, the findings indicate that for children in this age group vicariously learnt fear-related responses for one stimulus can subsequently be observed for a second stimulus without it being experienced in a fear-related vicarious learning event. These findings may help to explain why some individuals do not recall involvement of a traumatic learning episode in the development of their fear of a specific stimulus.

  2. Working memory coding of analog stimulus properties in the human prefrontal cortex.

    Science.gov (United States)

    Spitzer, Bernhard; Gloel, Matthias; Schmidt, Timo T; Blankenburg, Felix

    2014-08-01

    Building on evidence for working memory (WM) coding of vibrotactile frequency information in monkey prefrontal cortex, recent electroencephalography studies found frequency processing in human WM to be reflected by quantitative modulations of prefrontal upper beta activity (20-30 Hz) as a function of the to-be-maintained stimulus attribute. This kind of stimulus-dependent activity has been observed across different sensory modalities, suggesting a generalized role of prefrontal beta during abstract WM processing of quantitative magnitude information. However, until now the available empirical evidence for such quantitative WM representation remains critically limited to the retention of periodic stimulus frequencies. In the present experiment, we used retrospective cueing to examine the quantitative WM processing of stationary (intensity) and temporal (duration) attributes of a previously presented tactile stimulus. We found parametric modulations of prefrontal beta activity during cued WM processing of each type of quantitative information, in a very similar manner as had before been observed only for periodic frequency information. In particular, delayed prefrontal beta modulations systematically reflected the magnitude of the retrospectively selected stimulus attribute and were functionally linked to successful behavioral task performance. Together, these findings converge on a generalized role of stimulus-dependent prefrontal beta-band oscillations during abstract scaling of analog quantity information in human WM. © The Author 2013. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  3. The acute effect of a plyometric stimulus on jump performance in professional rugby players.

    Science.gov (United States)

    Tobin, Daniel P; Delahunt, Eamonn

    2014-02-01

    Post-activation potentiation (PAP) is the elevation of motor performance to a higher level in response to a conditioning stimulus. Extensive research exists examining the PAP effect after a heavy resistance exercise. However, there is limited research examining the PAP effect after a plyometric stimulus. This study was designed to examine whether a plyometric stimulus could produce a PAP effect comparable to that typically reported with a heavy resistance protocol. Importantly, it was hypothesized that the PAP effect would exist without the same levels of acute fatigue resulting from a heavy stimulus, thus allowing improvement in performance within a short rest interval range. Twenty professional rugby players were recruited for the study. Subjects performed 2 countermovement jumps (CMJs) at baseline and at 1, 3, and 5 minutes after a plyometric stimulus consisting of 40 jumps. Two separate 1-way repeated-measures analyses of variance were conducted to compare the dependent variables CMJ height and peak force at the 4 time points. Results of the Bonferroni adjusted pairwise comparisons indicated that jump height and peak force before plyometric exercises were significantly lower than all other time points (p plyometric exercises causes a significant acute enhancement in CMJ height (p plyometric series induced an improvement in CMJ height comparable to that reported elsewhere after a heavy lifting stimulus but without the need for a prolonged rest interval. Performing repeated series of plyometric jumps appears to be an efficient method of taking advantage of the PAP phenomenon, thus possibly eliminating the need for a complex training protocol.

  4. Effects of explicit cueing and ambiguity on the anticipation and experience of a painful thermal stimulus

    Science.gov (United States)

    Gibson, Stephen J.; Georgiou-Karistianis, Nellie; Giummarra, Melita J.

    2017-01-01

    Many factors can influence the way in which we perceive painful events and noxious stimuli, but less is known about how pain perception is altered by explicit knowledge about the impending sensation. This study aimed to investigate the impact of explicit cueing on anxiety, arousal, and pain experience during the anticipation and delivery of noxious thermal heat stimulations. Fifty-two healthy volunteers were randomised to receive explicit instructions about visual cue-stimulus temperature pairings, or no explicit instructions about the cue-stimulus pairs. A pain anxiety task was used to investigate the effects of explicit cueing on anticipatory anxiety, pain experience and electrophysiological responses. Participants who received explicit instructions about the cue-stimulus pairs (i.e., the relationship between the colour of the cue and the temperature of the associated stimuli) reported significantly higher subjective anxiety prior to the delivery of the thermal heat stimuli (p = .025, partial eta squared = .10). There were no effects of explicit cueing on subsequent pain intensity, unpleasantness, or the electrophysiological response to stimulus delivery. The perceived intensity and unpleasantness of the stimuli decreased across the blocks of the paradigm. In both groups anticipating the ambiguous cue elicited the largest change in electrophysiological arousal, indicating that not knowing the impending stimulus temperature led to increased arousal, compared to being certain of receiving a high temperature thermal stimulus (both p thermal stimuli. PMID:28832636

  5. The 5-HT1A Receptor and the Stimulus Effects of LSD in the Rat

    Science.gov (United States)

    Reissig, C.J.; Eckler, J.R.; Rabin, R.A.; Winter, J.C.

    2005-01-01

    Rationale It has been suggested that the 5-HT1A receptor plays a significant modulatory role in the stimulus effects of the indoleamine hallucinogen lysergic acid diethylamide (LSD). Objectives The present study sought to characterize the effects of several compounds with known affinity for the 5-HT1A receptor on the discriminative stimulus effects of LSD. Methods 12 Male F-344 rats were trained in a two-lever, fixed ratio10, food reinforced task with LSD (0.1 mg/kg; IP; 15 min pretreatment) as a discriminative stimulus. Combination and substitution tests with the 5-HT1A agonists, 8-OH-DPAT, buspirone, gepirone, and ipsapirone, with LSD-induced stimulus control were then performed. The effects of these 5-HT1A ligands were also tested in the presence of the selective 5-HT1A receptor antagonist, WAY-100,635 (0.3 mg/kg; SC; 30 min. pretreatment). Results In combination tests stimulus control by LSD was increased by all 5-HT1A receptor ligands with agonist properties. Similarly, in tests of antagonism, the increase in drug-appropriate responding caused by stimulation of the 5-HT1A receptor was abolished by administration of WAY-100,635. Conclusions These data, obtained using a drug discrimination model of the hallucinogenic effects of LSD, provide support for the hypothesis that the 5-HT1A receptor has a significant modulatory role in the stimulus effects of LSD. PMID:16025319

  6. Stimulus-Food Pairings Produce Stimulus-Directed Touch Screen Responding in Cynomolgus Monkeys ("Macaca Fascicularis") with or without a Positive Response Contingency

    Science.gov (United States)

    Bullock, Christopher E.; Myers, Todd M.

    2009-01-01

    Acquisition and maintenance of touch-screen responding was examined in naive cynomolgus monkeys ("Macaca fascicularis") under automaintenance and classical conditioning arrangements. In the first condition of Experiment 1, we compared acquisition of screen touching to a randomly positioned stimulus (a gray square) that was either stationary or…

  7. Symmetry and stimulus class formation in humans: Control by temporal location in a successive matching task.

    Science.gov (United States)

    Beurms, Sarah; Traets, Frits; De Houwer, Jan; Beckers, Tom

    2017-11-01

    Symmetry refers to the observation that subjects will derive B-A (e.g., in the presence of B, select A) after being trained on A-B (e.g., in the presence of A, select B). Whereas symmetry is readily shown in humans, it has been difficult to demonstrate in nonhuman animals. This difficulty, at least in pigeons, may result from responding to specific stimulus properties that change when sample and comparison stimuli switch roles between training and testing. In three experiments with humans, we investigated to what extent human responding is influenced by the temporal location of stimuli using a successive matching-to-sample procedure. Our results indicate that temporal location does not spontaneously control responding in humans, although it does in pigeons. Therefore, the number of functional stimuli that humans respond to in this procedure may be half of the number of functional stimuli that the pigeons respond to. In a fourth experiment, we tested this assumption by doubling the number of functional stimuli controlling responding in human participants in an attempt to make the test more comparable to symmetry tests with pigeons. Here, we found that humans responded according to indirect class formation in the same manner as pigeons do. In sum, our results indicate that functional symmetry is readily observed in humans, even in cases where the temporal features of the stimuli prevent functional symmetry in pigeons. We argue that this difference in behavior between the two species does not necessarily reflect a difference in capacity to show functional symmetry between both species, but could also reflect a difference in the functional stimuli each species responds to. © 2017 Society for the Experimental Analysis of Behavior.

  8. Hepatitis B virus DNA quantification with the three-in-one (3io) method allows accurate single-step differentiation of total HBV DNA and cccDNA in biopsy-size liver samples.

    Science.gov (United States)

    Taranta, Andrzej; Tien Sy, Bui; Zacher, Behrend Johan; Rogalska-Taranta, Magdalena; Manns, Michael Peter; Bock, Claus Thomas; Wursthorn, Karsten

    2014-08-01

    Hepatitis B virus (HBV) replicates via reverse transcription converting its partially double stranded genome into the covalently closed circular DNA (cccDNA). The long-lasting cccDNA serves as a replication intermediate in the nuclei of hepatocytes. It is an excellent, though evasive, parameter for monitoring the course of liver disease and treatment efficiency. To develop and test a new approach for HBV DNA quantification in serum and small-size liver samples. The p3io plasmid contains an HBV fragment and human β-actin gene (hACTB) as a standard. Respective TaqMan probes were labeled with different fluorescent dyes. A triplex real-time PCR for simultaneous quantification of total HBV DNA, cccDNA and hACTB could be established. Three-in-one method allows simultaneous analysis of 3 targets with a lower limit of quantification of 48 copies per 20 μl PCR reaction and a wide range of linearity (R(2)>0.99, pDNA samples from HBV infected patients. Total HBV DNA and cccDNA could be quantified in 32 and 22 of 33 FFPE preserved liver specimens, respectively. Total HBV DNA concentrations quantified by the 3io method remained comparable with Cobas TaqMan HBV Test v2.0. The three-in-one protocol allows the single step quantification of viral DNA in samples from different sources. Therefore lower sample input, faster data acquisition, a lowered error and significantly lower costs are the advantages of the method. Copyright © 2014 Elsevier B.V. All rights reserved.

  9. The speed of learning instructed stimulus-response association rules in human: experimental data and model.

    Science.gov (United States)

    Bugmann, Guido; Goslin, Jeremy; Duchamp-Viret, Patricia

    2013-11-06

    Humans can learn associations between visual stimuli and motor responses from just a single instruction. This is known to be a fast process, but how fast is it? To answer this question, we asked participants to learn a briefly presented (200ms) stimulus-response rule, which they then had to rapidly apply after a variable delay of between 50 and 1300ms. Participants showed a longer response time with increased variability for short delays. The error rate was low and did not vary with the delay, showing that participants were able to encode the rule correctly in less than 250ms. This time is close to the fastest synaptic learning speed deemed possible by diffusive influx of AMPA receptors. Learning continued at a slower pace in the delay period and was fully completed in average 900ms after rule presentation onset, when response latencies dropped to levels consistent with basic reaction times. A neural model was proposed that explains the reduction of response times and of their variability with the delay by (i) a random synaptic learning process that generates weights of average values increasing with the learning time, followed by (ii) random crossing of the firing threshold by a leaky integrate-and-fire neuron model, and (iii) assuming that the behavioural response is initiated when all neurons in a pool of m neurons have fired their first spike after input onset. Values of m=2 or 3 were consistent with the experimental data. The proposed model is the simplest solution consistent with neurophysiological knowledge. Additional experiments are suggested to test the hypothesis underlying the model and also to explore forgetting effects for which there were indications for the longer delay conditions. This article is part of a Special Issue entitled Neural Coding 2012. © 2013 Elsevier B.V. All rights reserved.

  10. Reducing audio stimulus presentation latencies across studies, laboratories, and hardware and operating system configurations.

    Science.gov (United States)

    Babjack, Destiny L; Cernicky, Brandon; Sobotka, Andrew J; Basler, Lee; Struthers, Devon; Kisic, Richard; Barone, Kimberly; Zuccolotto, Anthony P

    2015-09-01

    Using differing computer platforms and audio output devices to deliver audio stimuli often introduces (1) substantial variability across labs and (2) variable time between the intended and actual sound delivery (the sound onset latency). Fast, accurate audio onset latencies are particularly important when audio stimuli need to be delivered precisely as part of studies that depend on accurate timing (e.g., electroencephalographic, event-related potential, or multimodal studies), or in multisite studies in which standardization and strict control over the computer platforms used is not feasible. This research describes the variability introduced by using differing configurations and introduces a novel approach to minimizing audio sound latency and variability. A stimulus presentation and latency assessment approach is presented using E-Prime and Chronos (a new multifunction, USB-based data presentation and collection device). The present approach reliably delivers audio stimuli with low latencies that vary by ≤1 ms, independent of hardware and Windows operating system (OS)/driver combinations. The Chronos audio subsystem adopts a buffering, aborting, querying, and remixing approach to the delivery of audio, to achieve a consistent 1-ms sound onset latency for single-sound delivery, and precise delivery of multiple sounds that achieves standard deviations of 1/10th of a millisecond without the use of advanced scripting. Chronos's sound onset latencies are small, reliable, and consistent across systems. Testing of standard audio delivery devices and configurations highlights the need for careful attention to consistency between labs, experiments, and multiple study sites in their hardware choices, OS selections, and adoption of audio delivery systems designed to sidestep the audio latency variability issue.

  11. Nucleus accumbens and amygdala are possible substrates for the aversive stimulus effects of opiate withdrawal.

    Science.gov (United States)

    Stinus, L; Le Moal, M; Koob, G F

    1990-01-01

    Specific brain sites for the opiate abstinence syndrome syndrome have been elusive to delineate, and the classic overt signs of withdrawal such as wet dog shakes, ptosis and teeth chattering appear to be widely represented in the brain. Using a more general motivational test involving a disruption of operant behavior in dependent rats, the brain site most sensitive to the response disruptive effects of intracerebral administration of the opiate antagonist, methylnaloxonium, was the region of the nucleus accumbens, a site also implicated in the acute reinforcing properties of opiates. This disruption of operant responding was hypothesized to reflect the aversive properties of opiate withdrawal. The present study directly tested that hypothesis by exploring whether intercerebral administration of methylnaloxonium produced aversive stimulus effects as measured by the formation of place aversions. Rats implanted intracerebroventricularly or with bilateral cannulae aimed at the medial dorsal thalamus, periaqueductal gray, ventral tegmental area, amygdala or nucleus accumbens were made dependent on morphine by subcutaneous implantation of two 75-mg morphine pellets. The animals were then subjected to place aversion training by pairing of a distinct environment (one of three arms of a three-armed box with distinct texture, markings and smell) with a single injection of methylnaloxonium intracerebroventricularly or intracerebrally. Results showed that at high doses of methylnaloxonium (1000-2000 ng) all sites produced a place aversion. However, lower doses (250-500 ng) produced a significant brain site selectivity with the region of the nucleus accumbens the most sensitive. Observational measurements taken during the postinjection period with the high dose of methylnaloxonium showed that agitation was particularly observed following methylnaloxonium administration into the nucleus accumbens and periaqueductal gray.(ABSTRACT TRUNCATED AT 250 WORDS)

  12. CORTICAL ENCODING OF SIGNALS IN NOISE: EFFECTS OF STIMULUS TYPE AND RECORDING PARADIGM

    Science.gov (United States)

    Billings, Curtis J.; Bennett, Keri O.; Molis, Michelle R.; Leek, Marjorie R.

    2010-01-01

    Objectives Perception-in-noise deficits have been demonstrated across many populations and listening conditions. Many factors contribute to successful perception of auditory stimuli in noise, including neural encoding in the central auditory system. Physiological measures such as cortical auditory evoked potentials can provide a view of neural encoding at the level of the cortex that may inform our understanding of listeners’ abilities to perceive signals in the presence of background noise. In order to understand signal-in-noise neural encoding better, we set out to determine the effect of signal type, noise type, and evoking paradigm on the P1-N1-P2 complex. Design Tones and speech stimuli were presented to nine individuals in quiet, and in three background noise types: continuous speech spectrum noise, interrupted speech spectrum noise, and four-talker babble at a signal-to-noise ratio of −3 dB. In separate sessions, cortical auditory evoked potentials were evoked by a passive homogenous paradigm (single repeating stimulus) and an active oddball paradigm. Results The results for the N1 component indicated significant effects of signal type, noise type, and evoking paradigm. While components P1 and P2 also had significant main effects of these variables, only P2 demonstrated significant interactions among these variables. Conclusions Signal type, noise type, and evoking paradigm all must be carefully considered when interpreting signal-in-noise evoked potentials. Furthermore, these data confirm the possible usefulness of CAEPs as an aid to understanding perception-in-noise deficits. PMID:20890206

  13. Ensemble encoding of nociceptive stimulus intensity in the rat medial and lateral pain systems

    Directory of Open Access Journals (Sweden)

    Woodward Donald J

    2011-08-01

    Full Text Available Abstract Background The ability to encode noxious stimulus intensity is essential for the neural processing of pain perception. It is well accepted that the intensity information is transmitted within both sensory and affective pathways. However, it remains unclear what the encoding patterns are in the thalamocortical brain regions, and whether the dual pain systems share similar responsibility in intensity coding. Results Multichannel single-unit recordings were used to investigate the activity of individual neurons and neuronal ensembles in the rat brain following the application of noxious laser stimuli of increasing intensity to the hindpaw. Four brain regions were monitored, including two within the lateral sensory pain pathway, namely, the ventral posterior lateral thalamic nuclei and the primary somatosensory cortex, and two in the medial pathway, namely, the medial dorsal thalamic nuclei and the anterior cingulate cortex. Neuron number, firing rate, and ensemble spike count codings were examined in this study. Our results showed that the noxious laser stimulation evoked double-peak responses in all recorded brain regions. Significant correlations were found between the laser intensity and the number of responsive neurons, the firing rates, as well as the mass spike counts (MSCs. MSC coding was generally more efficient than the other two methods. Moreover, the coding capacities of neurons in the two pathways were comparable. Conclusion This study demonstrated the collective contribution of medial and lateral pathway neurons to the noxious intensity coding. Additionally, we provide evidence that ensemble spike count may be the most reliable method for coding pain intensity in the brain.

  14. The Effect of Cell Phone Conversation on Drivers’ Reaction Time to Audio Stimulus: Investigating the Theory of Multiple Resources and Central Resource of Attention

    Directory of Open Access Journals (Sweden)

    Seyed Kazem Mousavi-Sadati

    2011-01-01

    Full Text Available Objective: This research was aimed at investigating the theory of multiple resources and central resource of attention on secondary task performance of talking with two types of cell phone during driving. Materials & Methods: Using disposal sampling, 25 male participants were selected and their reaction to auditory stimulus in three different driving conditions (no conversation with phone, conversation with handheld phone and hands-free phone were recorded. Driving conditions have been changed from a participant to another participant in order to control the sequence of tests and participants familiarity with the test conditions. Results: the results of data analysis with descriptive statistics and Mauchly’s Test of Sphericity, One- factor repeated measures ANOVA and Paired-Samples T test showed that different driving conditions can affect the reaction time (P0.001. Phone Conversation with hands-free phone increases drivers’ simple reaction time to auditory stimulus (P<0.001. Using handheld phone does not increase drivers’ reaction time to auditory stimulus over hands-free phone (P<0.001. Conclusion: The results confirmed that the performance quality of dual tasks and multiple tasks can be predicted by Four-dimensional multiple resources model of attention and all traffic laws in connection with the handheld phone also have to be spread to the use of hands-free phone.

  15. The Facial Expression Action Stimulus Test. A test battery for the assessment of face memory, face and object perception, configuration processing and facial expression recognition

    Directory of Open Access Journals (Sweden)

    Beatrice eDe Gelder

    2015-10-01

    Full Text Available There are many ways to assess face perception skills. In this study, we describe a novel task battery FEAST (Facial Expression Action Stimulus Test developed to test recognition of identity and expressions of human faces as well as stimulus control categories. The FEAST consists of a neutral and emotional face memory task, a face and object identity matching task, a face and house part-to-whole matching task, and a human and animal facial expression matching task. The identity and part-to-whole matching tasks contain both upright and inverted conditions. The results provide reference data of a healthy sample of controls in two age groups for future users of the FEAST.

  16. Interoceptive conditioning with a nicotine stimulus is susceptible to reinforcer devaluation

    Science.gov (United States)

    Pittenger, Steven T.; Bevins, Rick A.

    2014-01-01

    Pavlovian conditioning processes contribute to the etiology of nicotine dependence. Conditioning involving interoceptive stimuli is increasingly recognized as playing a role in many diseases and psychopathologies, including drug addiction. Previous animal research on diminishing the influence of interoceptive conditioning has been limited to antagonism and non-reinforced exposures to the drug stimulus. The goal of the present research was to determine if interoceptive conditioning with a nicotine stimulus could be diminished through an unconditioned stimulus (US) devaluation procedure. In two separate experiments, male Sprague-Dawley rats received nicotine injections (0.4 mg base/kg) followed by intermittent sucrose (26%) access in a conditioning chamber. On intermixed saline sessions, sucrose was withheld. Conditioning was demonstrated by a reliable increase in head entries in the dipper receptacle on nicotine versus saline sessions. Following conditioning, rats in a devaluation condition were given access to sucrose in their home cages immediately followed by a lithium chloride (LiCl) injection on 3 consecutive days. On subsequent test days, nicotine-evoked conditioned responding was significantly attenuated. Within-subject (Experiment 1) and between-subject (Experiment 2) controls revealed that the diminished responding was not due to mere exposure to the sucrose US in the devaluation phase. Experiment 2 included a LiCl-alone control group. Repeated illness induced by LiCl did not reduce later nicotine-evoked responding. These findings suggest that there is a direct association between the interoceptive stimulus effects of nicotine and the appetitive sucrose US (i.e., stimulus-stimulus) rather than a stimulus-response association. PMID:23731077

  17. Self-triggered assistive stimulus training improves step initiation in persons with Parkinson’s disease

    Directory of Open Access Journals (Sweden)

    Creath Robert A

    2013-01-01

    Full Text Available Abstract Background Prior studies demonstrated that hesitation-prone persons with Parkinson’s disease (PDs acutely improve step initiation using a novel self-triggered stimulus that enhances lateral weight shift prior to step onset. PDs showed reduced anticipatory postural adjustment (APA durations, earlier step onsets, and faster 1st step speed immediately following stimulus exposure. Objective This study investigated the effects of long-term stimulus exposure. Methods Two groups of hesitation-prone subjects with Parkinson’s disease (PD participated in a 6-week step-initiation training program involving one of two stimulus conditions: 1 Drop. The stance-side support surface was lowered quickly (1.5 cm; 2 Vibration. A short vibration (100 ms was applied beneath the stance-side support surface. Stimuli were self-triggered by a 5% reduction in vertical force under the stance foot during the APA. Testing was at baseline, immediately post-training, and 6 weeks post-training. Measurements included timing and magnitude of ground reaction forces, and step speed and length. Results Both groups improved their APA force modulation after training. Contrary to previous results, neither group showed reduced APA durations or earlier step onset times. The vibration group showed 55% increase in step speed and a 39% increase in step length which were retained 6 weeks post-training. The drop group showed no stepping-performance improvements. Conclusions The acute sensitivity to the quickness-enhancing effects of stimulus exposure demonstrated in previous studies was supplanted by improved force modulation following prolonged stimulus exposure. The results suggest a potential approach to reduce the severity of start hesitation in PDs, but further study is needed to understand the relationship between short- and long-term effects of stimulus exposure.

  18. Low-density solvent-based dispersive liquid-liquid microextraction combined with single-drop microextraction for the fast determination of chlorophenols in environmental water samples by high performance liquid chromatography-ultraviolet detection.

    Science.gov (United States)

    Li, Xiaoyi; Xue, Aifang; Chen, Hao; Li, Shengqing

    2013-03-08

    A new format of fast three-phase microextraction by combining low-density solvent-based dispersive liquid-liquid microextraction (DLLME) and single-drop microextraction (SDME) was for the first time developed for the determination of chlorophenols in environmental water samples. The extraction procedure includes a 2 min DLLME pre-extraction and a 10 min SDME back-extraction. A portion of low-density solvent (toluene) was used as organic phase and injected into the aqueous sample (donor phase) with methanol as disperser. The analytes were pre-extracted into the organic phase within 2 min. A thin layer of the organic phase formed on the top of the aqueous phase by a 2 min centrifugation. Then a drop of acceptor solution was introduced into the upper layer and SDME was carried out for the back-extraction. The stirring step typically involved in SDME and LLLME is avoided with the benefit of the high speed and efficiency of DLLME pre-extraction. After extraction, the acceptor drop was withdrawn and directly injected into a high performance liquid chromatography instrument with ultraviolet detection for analysis. Five chlorophenols, 4-chlorophenol, 2-chlorophenol, 2,4-dichlorophenol, 2,4,6-trichlorophenol, and pentachlorophenol, were selected as model compounds for developing and evaluating the method. Factors affecting extraction efficiency were studied, including the organic solvent, the disperser solvent, the composition of donor phase and acceptor phase, the volume of acceptor microdrop, and the extraction time. At optimal conditions, the method showed low detection limit (0.016-0.084 μg/L) for the five chlorophenols, good linearity (from 0.2-250 to 1.0-250 μg/L, depending on the analytes) and repeatability (RSD below 8.2, n=5). The simple, fast, and efficient feature of the proposed method was demonstrated by the analysis of chlorophenols in environmental water samples. Copyright © 2013 Elsevier B.V. All rights reserved.

  19. Explicit authenticity and stimulus features interact to modulate BOLD response induced by emotional speech.

    Science.gov (United States)

    Drolet, Matthis; Schubotz, Ricarda I; Fischer, Julia

    2013-06-01

    Context has been found to have a profound effect on the recognition of social stimuli and correlated brain activation. The present study was designed to determine whether knowledge about emotional authenticity influences emotion recognition expressed through speech intonation. Participants classified emotionally expressive speech in an fMRI experimental design as sad, happy, angry, or fearful. For some trials, stimuli were cued as either authentic or play-acted in order to manipulate participant top-down belief about authenticity, and these labels were presented both congruently and incongruently to the emotional authenticity of the stimulus. Contrasting authentic versus play-acted stimuli during uncued trials indicated that play-acted stimuli spontaneously up-regulate activity in the auditory cortex and regions associated with emotional speech processing. In addition, a clear interaction effect of cue and stimulus authenticity showed up-regulation in the posterior superior temporal sulcus and the anterior cingulate cortex, indicating that cueing had an impact on the perception of authenticity. In particular, when a cue indicating an authentic stimulus was followed by a play-acted stimulus, additional activation occurred in the temporoparietal junction, probably pointing to increased load on perspective taking in such trials. While actual authenticity has a significant impact on brain activation, individual belief about stimulus authenticity can additionally modulate the brain response to differences in emotionally expressive speech.

  20. Dissecting stimulus-response binding effects: Grouping by color separately impacts integration and retrieval processes.

    Science.gov (United States)

    Laub, Ruth; Frings, Christian; Moeller, Birte

    2018-04-23

    In selection tasks, target and distractor features can be encoded together with the response into the same short-lived memory trace, or event file (see Hommel, 2004), leading to bindings between stimulus and response features. The repetition of a stored target or distractor feature can lead to the retrieval of the entire episode, including the response-so-called "binding effects." Binding effects due to distractor repetition are stronger for grouped than for nongrouped target and distractor stimulus configurations. Modulation of either of two mechanisms that lead to the observed binding effects might be responsible here: Grouping may influence either stimulus-response integration or stimulus-response retrieval. In the present study we investigated the influences of grouping on both mechanisms independently. In two experiments, target and distractor letters were grouped (or nongrouped) via color (dis)similarity separately during integration and retrieval. Grouping by color similarity affected integration and retrieval mechanisms independently and in different ways. Color dissimilarity enhanced distractor-based retrieval, whereas color similarity enhanced distractor integration. We concluded that stimulus grouping is relevant for binding effects, but that the mechanisms that contribute to binding effects should be carefully separated.

  1. Anticipation increases tactile stimulus processing in the ipsilateral primary somatosensory cortex.

    Science.gov (United States)

    van Ede, Freek; de Lange, Floris P; Maris, Eric

    2014-10-01

    Stimulus anticipation improves perception. To account for this improvement, we investigated how stimulus processing is altered by anticipation. In contrast to a large body of previous work, we employed a demanding perceptual task and investigated sensory responses that occur beyond early evoked activity in contralateral primary sensory areas: Stimulus-induced modulations of neural oscillations. For this, we recorded magnetoencephalography in 19 humans while they performed a cued tactile identification task involving the identification of either a proximal or a distal stimulation on the fingertips. We varied the cue-target interval between 0 and 1000 ms such that tactile targets occurred at various degrees of anticipation. This allowed us to investigate the influence of anticipation on stimulus processing in a parametric fashion. We observed that anticipation increases the stimulus-induced response (suppression of beta-band oscillations) originating from the ipsilateral primary somatosensory cortex. This occurs in the period in which the tactile memory trace is analyzed and is correlated with the anticipation-induced improvement in tactile perception. We propose that this ipsilateral response indicates distributed processing across bilateral primary sensory cortices, of which the extent increases with anticipation. This constitutes a new and potentially important mechanism contributing to perception and its improvement following anticipation. © The Author 2013. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  2. Sequential modulation of distractor-interference produced by semantic generalization of stimulus features

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    Mike eWendt

    2014-11-01

    Full Text Available Sequential modulations of distractor-related interference (i.e., reduced congruency effect after incongruent as compared to congruent predecessor trials, a.k.a. Gratton effect have been taken to reflect conflict-induced attentional focusing. To dismiss an alternative interpretation based on integration and retrieval of low-level features, it is important to exert experimental control of stimulus and response feature sequences. This has been achieved by considering only trials associated with complete feature changes. Furthermore, distractors from two different perceptual dimensions, such as stimulus location and shape, have been combined in the same experiment to investigate the question of specificity vs. generality of conflict adaptation. With this method feature sequence control can be exerted, in principle, without disregarding data from feature repetition trials. However, such control may be insufficient when the distractor dimensions overlap semantically. In two experiments we found evidence consistent with the assumption that semantic generalization of stimulus features, such as between a stimulus presented at a left-sided location and a stimulus shape pointing to the left, may yield a between-dimension Gratton effect. These findings raise doubts about inferring generalized attentional conflict adaptation when semantically related distractor dimensions are used.

  3. Need for Space: The Key Distance Effect Depends on Spatial Stimulus Configurations

    Science.gov (United States)

    Stephan, Julia; Franz, Volker H.

    2014-01-01

    In numerous psychological experiments, participants classify stimuli by pressing response keys. According to Lakens, Schneider, Jostmann, and Schubert (2011), classification performance is affected by physical distance between response keys – indicating a cognitive tendency to represent categories in spatial code. However, previous evidence for a key distance effect (KDE) from a color-naming Stroop task is inconclusive as to whether: (a) key separation automatically leads to an internal spatial representation of non-spatial stimulus characteristics in participants, or if the KDE rather depends on physical spatial characteristics of the stimulus configuration; (b) the KDE attenuates the Stroop interference effect. We therefore first adopted the original Stroop task in Experiment 1, confirming that wider key distance facilitated responses, but did not modulate the Stroop effect as was previously found. In Experiments 2 and 3 we controlled potential mediator variables in the original design. When we did not display instructions about stimulus-response mappings, thereby removing the unintended spatial context from the Stroop stimuli, no KDE emerged. Presenting the instructions at a central position in Experiment 4 confirmed that key separation alone is not sufficient for a KDE, but correspondence between spatial configurations of stimuli and responses is also necessary. Evidence indicates that the KDE on Stroop performance is due to known mechanisms of stimulus-response compatibility and response discriminability. The KDE does, however, not demonstrate a general disposition to represent any stimulus in spatial code. PMID:24642888

  4. Effects of age, gender, and stimulus presentation period on visual short-term memory.

    Science.gov (United States)

    Kunimi, Mitsunobu

    2016-01-01

    This study focused on age-related changes in visual short-term memory using visual stimuli that did not allow verbal encoding. Experiment 1 examined the effects of age and the length of the stimulus presentation period on visual short-term memory function. Experiment 2 examined the effects of age, gender, and the length of the stimulus presentation period on visual short-term memory function. The worst memory performance and the largest performance difference between the age groups were observed in the shortest stimulus presentation period conditions. The performance difference between the age groups became smaller as the stimulus presentation period became longer; however, it did not completely disappear. Although gender did not have a significant effect on d' regardless of the presentation period in the young group, a significant gender-based difference was observed for stimulus presentation periods of 500 ms and 1,000 ms in the older group. This study indicates that the decline in visual short-term memory observed in the older group is due to the interaction of several factors.

  5. Corporate Governance Characteristics as a Stimulus to Tax Management

    Directory of Open Access Journals (Sweden)

    Antônio Paulo Machado Gomes

    2016-01-01

    Full Text Available This article aimed to investigate whether corporate governance uses tax management to increase companies' performance. The objective was checking whether corporate governance characteristics, such as remuneration paid to the executive board, segregation between Chairman and CEO, and the independence and composition of the Board of Directors, influence tax management in Brazilian companies. At the same time, it aimed to identify whether the preceding tax management is reflected on the subsequent tax management. To do this, a sample of 355 Brazilian companies listed on the BM&FBOVESPA between 2008 and 2014 was used, in order to find out whether their corporate governance characteristics influenced tax management, something identified by calculating ETR, CashETR, and BTD. As a result, it was found (i that the remuneration paid to executives may be regarded as a characteristic influencing tax management in Brazilian firms, and (ii that the preceding tax management influences the future tax management. In addition, it was found that Brazilian companies do not rule out tax management benefits, since the average effective rate in the sample under analysis was 25%, and it is statistically lower than the nominal rate of taxes on earnings in Brazil, which is 34%.

  6. Near-infrared spectroscopic imaging of stimulus-related hemodynamic responses on the neonatal auditory cortices

    Science.gov (United States)

    Kotilahti, Kalle; Nissila, Ilkka; Makela, Riikka; Noponen, Tommi; Lipiainen, Lauri; Gavrielides, Nasia; Kajava, Timo; Huotilainen, Minna; Fellman, Vineta; Merilainen, Pekka; Katila, Toivo

    2005-04-01

    We have used near-infrared spectroscopy (NIRS) to study hemodynamic auditory evoked responses on 7 full-term neonates. Measurements were done simultaneously above both auditory cortices to study the distribution of speech and music processing between hemispheres using a 16-channel frequency-domain instrument. The stimulation consisted of 5-second samples of music and speech with a 25-second silent interval. In response to stimulation, a significant increase in the concentration of oxygenated hemoglobin ([HbO2]) was detected in 6 out of 7 subjects. The strongest responses in [HbO2] were seen near the measurement location above the ear on both hemispheres. The mean latency of the maximum responses was 9.42+/-1.51 s. On the left hemisphere (LH), the maximum amplitude of the average [HbO2] response to the music stimuli was 0.76+/- 0.38 μ M (mean+/-std.) and to the speech stimuli 1.00+/- 0.45 μ+/- μM. On the right hemisphere (RH), the maximum amplitude of the average [HbO2] response was 1.29+/- 0.85 μM to the music stimuli and 1.23+/- 0.93 μM to the speech stimuli. The results indicate that auditory information is processed on both auditory cortices, but LH is more concentrated to process speech than music information. No significant differences in the locations and the latencies of the maximum responses relative to the stimulus type were found.

  7. Effect of stimulus configuration on crowding in strabismic amblyopia.

    Science.gov (United States)

    Norgett, Yvonne; Siderov, John

    2017-11-01

    Foveal vision in strabismic amblyopia can show increased levels of crowding, akin to typical peripheral vision. Target-flanker similarity and visual-acuity test configuration may cause the magnitude of crowding to vary in strabismic amblyopia. We used custom-designed visual acuity tests to investigate crowding in observers with strabismic amblyopia. LogMAR was measured monocularly in both eyes of 11 adults with strabismic or mixed strabismic/anisometropic amblyopia using custom-designed letter tests. The tests used single-letter and linear formats with either bar or letter flankers to introduce crowding. Tests were presented monocularly on a high-resolution display at a test distance of 4 m, using standardized instructions. For each condition, five letters of each size were shown; testing continued until three letters of a given size were named incorrectly. Uncrowded logMAR was subtracted from logMAR in each of the crowded tests to highlight the crowding effect. Repeated-measures ANOVA showed that letter flankers and linear presentation individually resulted in poorer performance in the amblyopic eyes (respectively, mean normalized logMAR = 0.29, SE = 0.07, mean normalized logMAR = 0.27, SE = 0.07; p 0.05). Both linear presentation and letter rather than bar flankers increase crowding in the amblyopic eyes of people with strabismic amblyopia. These results suggest the influence of more than one mechanism contributing to crowding in linear visual-acuity charts with letter flankers.

  8. The Bodily Expressive Action Stimulus Test (BEAST). Construction and Validation of a Stimulus Basis for Measuring Perception of Whole Body Expression of Emotions.

    Science.gov (United States)

    de Gelder, Beatrice; Van den Stock, Jan

    2011-01-01

    Whole body expressions are among the main visual stimulus categories that are naturally associated with faces and the neuroscientific investigation of how body expressions are processed has entered the research agenda this last decade. Here we describe the stimulus set of whole body expressions termed bodily expressive action stimulus test (BEAST), and we provide validation data for use of these materials by the community of emotion researchers. The database was composed of 254 whole body expressions from 46 actors expressing 4 emotions (anger, fear, happiness, and sadness). In all pictures the face of the actor was blurred and participants were asked to categorize the emotions expressed in the stimuli in a four alternative-forced-choice task. The results show that all emotions are well recognized, with sadness being the easiest, followed by fear, whereas happiness was the most difficult. The BEAST appears a valuable addition to currently available tools for assessing recognition of affective signals. It can be used in explicit recognition tasks as well as in matching tasks and in implicit tasks, combined either with facial expressions, with affective prosody, or presented with affective pictures as context in healthy subjects as well as in clinical populations.

  9. Boat sampling

    International Nuclear Information System (INIS)

    Citanovic, M.; Bezlaj, H.

    1994-01-01

    This presentation describes essential boat sampling activities: on site boat sampling process optimization and qualification; boat sampling of base material (beltline region); boat sampling of weld material (weld No. 4); problems accompanied with weld crown varieties, RPV shell inner radius tolerance, local corrosion pitting and water clarity. The equipment used for boat sampling is described too. 7 pictures

  10. The Wada Test: contributions to standardization of the stimulus for language and memory assessment

    Directory of Open Access Journals (Sweden)

    Mäder Maria Joana

    2004-01-01

    Full Text Available The Wada Test (WT is part of the presurgical evaluation for refractory epilepsy. The WT is not standardized and the protocols differ in important ways, including stimulus type of material presented for memory testing, timing of presentations and methods of assessment. The aim of this study was to contribute to establish parameters for a WT to Brazilian population investigating the performance of 100 normal subjects, without medication. Two parallel models were used based on Montreal Procedure adapted from Gail Risse's (MEG-MN,EUA protocol. The proportions of correct responses of normal subjects submitted to two parallel WT models were investigated and the two models were compared. The results showed that the two models are similar but significant differences among the stimulus type were observed. The results suggest that the stimulus type may influence the results of the WT and should be considered when constructing models and comparing different protocols.

  11. Finding the missing stimulus mismatch negativity (MMN): Emitted MMN to violations of an auditory gestalt

    Science.gov (United States)

    Salisbury, Dean F

    2011-01-01

    Deviations from repetitive auditory stimuli evoke a mismatch negativity (MMN). Counter-intuitively, omissions of repetitive stimuli do not. Violations of patterns reflecting complex rules also evoke MMN. To detect a MMN to missing stimuli, we developed an auditory gestalt task using one stimulus. Groups of 6 pips (50 msec duration, 330 msec stimulus onset asynchrony (SOA), 400 trials), were presented with an inter-trial interval (ITI) of 750 msec while subjects (n=16) watched a silent video. Occasional deviant groups had missing 4th or 6th tones (50 trials each). Missing stimuli evoked a MMN (pgestalt grouping rule. Homogenous stimulus streams appear to differ in the relative weighting of omissions than strongly patterned streams. PMID:22221004

  12. Stimulus fear-relevance and the vicarious learning pathway to childhood fears.

    Science.gov (United States)

    Askew, Chris; Dunne, Güler; Özdil, Zehra; Reynolds, Gemma; Field, Andy P

    2013-10-01

    Enhanced fear learning for fear-relevant stimuli has been demonstrated in procedures with adults in the laboratory. Three experiments investigated the effect of stimulus fear-relevance on vicarious fear learning in children (aged 6-11 years). Pictures of stimuli with different levels of fear-relevance (flowers, caterpillars, snakes, worms, and Australian marsupials) were presented alone or together with scared faces. In line with previous studies, children's fear beliefs and avoidance preferences increased for stimuli they had seen with scared faces. However, in contrast to evidence with adults, learning was mostly similar for all stimulus types irrespective of fear-relevance. The results support a proposal that stimulus preparedness is bypassed when children observationally learn threat-related information from adults.

  13. The Hall-Rodriguez theory of latent inhibition: Further assessment of compound stimulus preexposure effects.

    Science.gov (United States)

    Rodríguez, Gabriel; Márquez, Raúl; Gil, Marta; Alonso, Gumersinda; Hall, Geoffrey

    2014-10-01

    According to a recent theory (Hall & Rodriguez, 2010), the latent inhibition produced by nonreinforced exposure to a target stimulus (B) will be deepened by subsequent exposure of that stimulus in compound with another (AB). This effect of compound exposure is taken to depend on the addition of a novel A to the familiar B and is not predicted for equivalent preexposure on which AB trials precede the A trials. This prediction was tested in 2 experiments using rats. Experiment 1 used an aversive procedure with flavors as the stimuli; Experiment 2 used an appetitive procedure with visual and auditory stimuli. In both, we found that conditioning with B as the conditioned stimulus proceeded more slowly (i.e., latent inhibition was greater) in subjects given the B-AB sequence in preexposure than in subjects given the AB-B sequence.

  14. Stimulus meanings alter illusory self-motion (vection)--experimental examination of the train illusion.

    Science.gov (United States)

    Seno, Takeharu; Fukuda, Haruaki

    2012-01-01

    Over the last 100 years, numerous studies have examined the effective visual stimulus properties for inducing illusory self-motion (known as vection). This vection is often experienced more strongly in daily life than under controlled experimental conditions. One well-known example of vection in real life is the so-called 'train illusion'. In the present study, we showed that this train illusion can also be generated in the laboratory using virtual computer graphics-based motion stimuli. We also demonstrated that this vection can be modified by altering the meaning of the visual stimuli (i.e., top down effects). Importantly, we show that the semantic meaning of a stimulus can inhibit or facilitate vection, even when there is no physical change to the stimulus.

  15. Estimation of the kinetic-optimized stimulus intensity envelope for drop foot gait rehabilitation.

    Science.gov (United States)

    Tanabe, S; Kubota, S; Itoh, N; Kimura, T; Muraoka, Y; Shimizu, A; Kanada, Y

    2012-05-01

    The purpose of present study is to estimate the optimal stimulus intensity envelope for drop foot rehabilitation based on a kinetic perspective. The voluntary and electric-stimulated elicited dorsiflexion torque responses of 11 healthy subjects were measured. During dorsiflexion, we recorded the tibialis anterior (TA) electromyography (EMG) or the stimulation intensity at four angles of the ankle joint. From these measurements, we derived two approximate equations that estimate dorsiflexion produced by either voluntary contraction or by electrical stimulation using a sigmoid function and a stepwise-regression analysis. We then tested the predictive capability of the model using Pearson correlation. Both equations indicated high correlation coefficients. Finally, we derived a relation between the TA EMG amplitude and stimulation intensity. From the obtained equation, we determined the optimal stimulus amplitude. We assume that the derived stimulus intensity envelope, calculated from EMG amplitude and angle of ankle joint, satisfies kinetic demand.

  16. Spontaneous pre-stimulus fluctuations in the activity of right fronto-parietal areas influence inhibitory control performance

    Directory of Open Access Journals (Sweden)

    Camille F. Chavan

    2013-06-01

    Full Text Available Inhibitory control refers to the ability to suppress planned or ongoing cognitive or motor processes. Electrophysiological indices of inhibitory control failure have been found to manifest even before the presentation of the stimuli triggering the inhibition, suggesting that pre-stimulus brain-states modulate inhibition performance. However, previous electrophysiological investigations on the state-dependency of inhibitory control were based on averaged event-related potentials, a method eliminating the variability in the ongoing brain activity not time-locked to the event of interest. These studies thus left unresolved whether spontaneous variations in the brain-state immediately preceding unpredictable inhibition-triggering stimuli also influence inhibitory control performance.To address this question, we applied single-trial EEG topographic analyses on the time interval immediately preceding NoGo stimuli in conditions where the responses to NoGo trials were correctly inhibited (correct rejection vs. committed (false alarms during an auditory spatial Go/NoGo task.We found a specific configuration of the EEG voltage field manifesting more frequently before correctly inhibited responses to NoGo stimuli than before false alarms. There was no evidence for an EEG topography occurring more frequently before false alarms than before correct rejections. The visualization of distributed electrical source estimations of the EEG topography preceding successful response inhibition suggested that it resulted from the activity of a right fronto-parietal brain network.Our results suggest that the fluctuations in the ongoing brain activity immediately preceding stimulus presentation contribute to the behavioral outcomes during an inhibitory control task. Our results further suggest that the state-dependency of sensory-cognitive processing might not only concern perceptual processes, but also high-order, top-down inhibitory control mechanisms.

  17. Duration of the Unconditioned Stimulus in Appetitive Conditioning of Honeybees Differentially Impacts Learning, Long-Term Memory Strength, and the Underlying Protein Synthesis

    Science.gov (United States)

    Marter, Kathrin; Grauel, M. Katharina; Lewa, Carmen; Morgenstern, Laura; Buckemüller, Christina; Heufelder, Karin; Ganz, Marion; Eisenhardt, Dorothea

    2014-01-01

    This study examines the role of stimulus duration in learning and memory formation of honeybees ("Apis mellifera"). In classical appetitive conditioning honeybees learn the association between an initially neutral, conditioned stimulus (CS) and the occurrence of a meaningful stimulus, the unconditioned stimulus (US). Thereby the CS…

  18. Comparison of the discriminative stimulus effects of dimethyltryptamine with different classes of psychoactive compounds in rats.

    Science.gov (United States)

    Gatch, Michael B; Rutledge, Margaret A; Carbonaro, Theresa; Forster, Michael J

    2009-07-01

    There has been increased recreational use of dimethyltryptamine (DMT), but little is known of its discriminative stimulus effects. The present study assessed the similarity of the discriminative stimulus effects of DMT to other types of hallucinogens and to psychostimulants. Rats were trained to discriminate DMT from saline. To test the similarity of DMT to known hallucinogens, the ability of (+)-lysergic acid diethylamide (LSD), (-)-2,5-dimethoxy-4-methylamphetamine (DOM), (+)-methamphetamine, or (+/-)3,4-methylenedioxymethyl amphetamine (MDMA) to substitute in DMT-trained rats was tested. The ability of DMT to substitute in rats trained to discriminate each of these compounds was also tested. To assess the degree of similarity in discriminative stimulus effects, each of the compounds was tested for substitution in all of the other training groups. LSD, DOM, and MDMA all fully substituted in DMT-trained rats, whereas DMT fully substituted only in DOM-trained rats. Full cross-substitution occurred between DMT and DOM, LSD and DOM, and (+)-methamphetamine and MDMA. MDMA fully substituted for (+)-methamphetamine, DOM, and DMT, but only partially for LSD. In MDMA-trained rats, LSD and (+)-methamphetamine fully substituted, whereas DMT and DOM did not fully substitute. No cross-substitution was evident between (+)-methamphetamine and DMT, LSD, or DOM. DMT produces discriminative stimulus effects most similar to those of DOM, with some similarity to the discriminative stimulus effects of LSD and MDMA. Like DOM and LSD, DMT seems to produce predominately hallucinogenic-like discriminative stimulus effects and minimal psychostimulant effects, in contrast to MDMA which produced hallucinogen- and psychostimulant-like effects.

  19. Hemispheric asymmetry for affective stimulus processing in healthy subjects--a fMRI study.

    Directory of Open Access Journals (Sweden)

    Esther Beraha

    Full Text Available BACKGROUND: While hemispheric specialization of language processing is well established, lateralization of emotion processing is still under debate. Several conflicting hypotheses have been proposed, including right hemisphere hypothesis, valence asymmetry hypothesis and region-specific lateralization hypothesis. However, experimental evidence for these hypotheses remains inconclusive, partly because direct comparisons between hemispheres are scarce. METHODS: The present fMRI study systematically investigated functional lateralization during affective stimulus processing in 36 healthy participants. We normalized our functional data on a symmetrical template to avoid confounding effects of anatomical asymmetries. Direct comparison of BOLD responses between hemispheres was accomplished taking two approaches: a hypothesis-driven region of interest analysis focusing on brain areas most frequently reported in earlier neuroimaging studies of emotion; and an exploratory whole volume analysis contrasting non-flipped with flipped functional data using paired t-test. RESULTS: The region of interest analysis revealed lateralization towards the left in the medial prefrontal cortex (BA 10 during positive stimulus processing; while negative stimulus processing was lateralized towards the right in the dorsolateral prefrontal cortex (BA 9 & 46 and towards the left in the amygdala and uncus. The whole brain analysis yielded similar results and, in addition, revealed lateralization towards the right in the premotor cortex (BA 6 and the temporo-occipital junction (BA 19 & 37 during positive stimulus processing; while negative stimulus processing showed lateralization towards the right in the temporo-parietal junction (BA 37,39,42 and towards the left in the middle temporal gyrus (BA 21. CONCLUSION: Our data suggests region-specific functional lateralization of emotion processing. Findings show valence asymmetry for prefrontal cortical areas and left

  20. Optimization of Stimulus Characteristics for Vestibular Stochastic Resonance to Improve Balance Function

    Science.gov (United States)

    Mulavara, Ajitkumar; Fiedler, Matthew; Kofman, Igor; Acock, Keena; DeDios, Yiri E.; Heap, Erin; Peters, Brian; Wood, Scott; Serrador, Jorge; Cohen, Helen; hide

    2010-01-01

    Stochastic resonance (SR) is a mechanism by which noise can assist and enhance the response of neural systems to relevant sensory signals. Recent studies have shown that applying imperceptible stochastic noise electrical stimulation to the vestibular system significantly improved balance and ocular motor responses. The goal of this study was to optimize the amplitude of the stochastic vestibular signals for balance performance during standing on an unstable surface. Subjects performed a standardized balance task of standing on a block of 10-cm-thick medium-density foam with their eyes closed. Balance performance was measured using a force plate under the foam block and using inertial motion sensors placed on the torso and head segments. Stochastic electrical stimulation was applied to the vestibular system through electrodes placed over the mastoid process. Subjects were tested at seven amplitudes in the 0.01-30Hz frequency range. The root mean square of the signal increased by 30 microamperes for each +/-100 microampere increment in the current range of 0 - +/-700 microampere. Six balance parameters were calculated to characterize the performance of subjects during the baseline and the stimulus periods for all seven amplitudes. Optimal stimulus amplitude was determined as the one at which the ratio of parameters from the stimulus period to the baseline period for any amplitude range was less than that for the no stimulus condition on a minimum of four of six parameters. Results from this study showed that balance performance at the optimal stimulus amplitude showed significant improvement with the application of the vestibular SR stimulation. The amplitude of optimal stimulus for improving balance performance in normal subjects was in the range of +/-100 - +/-300 microamps.

  1. Stimulus point distribution in deep or superficial peroneal nerve for treatment of ankle spasticity.

    Science.gov (United States)

    Kubota, Shinji; Tanabe, Shigeo; Sugawara, Kenichi; Muraoka, Yoshihiro; Itoh, Norihide; Kanada, Yoshikiyo

    2013-01-01

     To develop effective electrical stimulation treatment to reduce spasticity, we examined the optimal stimulus point of the common peroneal nerve.  The locations of selective stimulus points for the deep peroneal nerve or superficial peroneal nerve fiber were examined in 25 healthy subjects in both legs (50 legs) using the ratio of the tibialis anterior (TA) to the peroneus longus (PL) M-wave amplitude (TA/PL ratio). In addition, we measured reciprocal Ia inhibition in ten healthy subjects. The amount of inhibition was determined from short-latency suppression of the soleus (Sol) H-reflex by conditioning stimuli to the deep or superficial peroneal nerve. The paired t-test was used for statistical analysis.  The mean TA/PL ratio during deep peroneal nerve stimulation was significantly different from superficial peroneal nerve stimulation (p < 0.001). The mean stimulus point for the deep peroneal nerve was located 7 ± 5 mm distal and 3 ± 6 mm anterior from the distal edges of the head of fibula and was markedly different from the stimulus point for the superficial peroneal nerve (20 ± 7 mm distal and 12 ± 8 mm posterior). During deep peroneal nerve stimulation, the mean conditioned H-reflex was depressed to 83.8 ± 10.7% of the unconditioned value of the H-reflex. In contrast, during superficial peroneal nerve stimulation, the mean conditioned H-reflex increased to 105.3 ± 5.2%. These values were significantly different (p < 0.001).  In the present study, we revealed a stimulus area of the deep peroneal nerve. Also, we observed the inhibitory effects of stimulation upon the deep peroneal nerve at individual stimulus point. Our results appear to indicate that localized stimulation of the deep peroneal nerve is more useful for the reduction of ankle spasticity. © 2012 International Neuromodulation Society.

  2. Oscillatory Mechanisms of Stimulus Processing and Selection in the Visual and Auditory Systems: State-of-the-Art, Speculations and Suggestions

    Directory of Open Access Journals (Sweden)

    Benedikt Zoefel

    2017-05-01

    Full Text Available All sensory systems need to continuously prioritize and select incoming stimuli in order to avoid overflow or interference, and provide a structure to the brain's input. However, the characteristics of this input differ across sensory systems; therefore, and as a direct consequence, each sensory system might have developed specialized strategies to cope with the continuous stream of incoming information. Neural oscillations are intimately connected with this selection process, as they can be used by the brain to rhythmically amplify or attenuate input and therefore represent an optimal tool for stimulus selection. In this paper, we focus on oscillatory processes for stimulus selection in the visual and auditory systems. We point out both commonalities and differences between the two systems and develop several hypotheses, inspired by recently published findings: (1 The rhythmic component in its input is crucial for the auditory, but not for the visual system. The alignment between oscillatory phase and rhythmic input (phase entrainment is therefore an integral part of stimulus selection in the auditory system whereas the visual system merely adjusts its phase to upcoming events, without the need for any rhythmic component. (2 When input is unpredictable, the visual system can maintain its oscillatory sampling, whereas the auditory system switches to a different, potentially internally oriented, “mode” of processing that might be characterized by alpha oscillations. (3 Visual alpha can be divided into a faster occipital alpha (10 Hz and a slower frontal alpha (7 Hz that critically depends on attention.

  3. The ToMenovela – A photograph-based stimulus set for the study of social cognition with high ecological validity

    Directory of Open Access Journals (Sweden)

    Maike C. Herbort

    2016-12-01

    Full Text Available We present the ToMenovela, a stimulus set that has been developed to provide a set of normatively rated socio-emotional stimuli showing varying amount of characters in emotionally laden interactions for experimental investigations of i cognitive and ii affective ToM, iii emotional reactivity, and iv complex emotion judgment with respect to Ekman’s basic emotions (happiness, sadness, anger, fear, surprise and disgust, Ekman & Friesen, 1975. Stimuli were generated with focus on ecological validity and consist of 190 scenes depicting daily-life situations. Two or more of eight main characters with distinct biographies and personalities are depicted on each scene picture.To obtain an initial evaluation of the stimulus set and to pave the way for future studies in clinical populations, normative data on each stimulus of the set was obtained from a sample of 61 neurologically and psychiatrically healthy participants (31 female, 30 male; mean age 26.74 +/- 5.84, including a visual analog scale rating of Ekman’s basic emotions (happiness, sadness, anger, fear, surprise and disgust and free-text descriptions of the content. The ToMenovela is being developed to provide standardized material of social scenes that are available to researchers in the study of social cognition. It should facilitate experimental control while keeping ecological validity high.

  4. Oscillatory Mechanisms of Stimulus Processing and Selection in the Visual and Auditory Systems: State-of-the-Art, Speculations and Suggestions.

    Science.gov (United States)

    Zoefel, Benedikt; VanRullen, Rufin

    2017-01-01

    All sensory systems need to continuously prioritize and select incoming stimuli in order to avoid overflow or interference, and provide a structure to the brain's input. However, the characteristics of this input differ across sensory systems; therefore, and as a direct consequence, each sensory system might have developed specialized strategies to cope with the continuous stream of incoming information. Neural oscillations are intimately connected with this selection process, as they can be used by the brain to rhythmically amplify or attenuate input and therefore represent an optimal tool for stimulus selection. In this paper, we focus on oscillatory processes for stimulus selection in the visual and auditory systems. We point out both commonalities and differences between the two systems and develop several hypotheses, inspired by recently published findings: (1) The rhythmic component in its input is crucial for the auditory, but not for the visual system. The alignment between oscillatory phase and rhythmic input (phase entrainment) is therefore an integral part of stimulus selection in the auditory system whereas the visual system merely adjusts its phase to upcoming events, without the need for any rhythmic component. (2) When input is unpredictable, the visual system can maintain its oscillatory sampling, whereas the auditory system switches to a different, potentially internally oriented, "mode" of processing that might be characterized by alpha oscillations. (3) Visual alpha can be divided into a faster occipital alpha (10 Hz) and a slower frontal alpha (7 Hz) that critically depends on attention.

  5. Analytical Bias Exceeding Desirable Quality Goal in 4 out of 5 Common Immunoassays: Results of a Native Single Serum Sample External Quality Assessment Program for Cobalamin, Folate, Ferritin, Thyroid-Stimulating Hormone, and Free T4 Analyses.

    Science.gov (United States)

    Kristensen, Gunn B B; Rustad, Pål; Berg, Jens P; Aakre, Kristin M

    2016-09-01

    We undertook this study to evaluate method differences for 5 components analyzed by immunoassays, to explore whether the use of method-dependent reference intervals may compensate for method differences, and to investigate commutability of external quality assessment (EQA) materials. Twenty fresh native single serum samples, a fresh native serum pool, Nordic Federation of Clinical Chemistry Reference Serum X (serum X) (serum pool), and 2 EQA materials were sent to 38 laboratories for measurement of cobalamin, folate, ferritin, free T4, and thyroid-stimulating hormone (TSH) by 5 different measurement procedures [Roche Cobas (n = 15), Roche Modular (n = 4), Abbott Architect (n = 8), Beckman Coulter Unicel (n = 2), and Siemens ADVIA Centaur (n = 9)]. The target value for each component was calculated based on the mean of method means or measured by a reference measurement procedure (free T4). Quality specifications were based on biological variation. Local reference intervals were reported from all laboratories. Method differences that exceeded acceptable bias were found for all components except folate. Free T4 differences from the uncommonly used reference measurement procedure were large. Reference intervals differed between measurement procedures but also within 1 measurement procedure. The serum X material was commutable for all components and measurement procedures, whereas the EQA materials were noncommutable in 13 of 50 occasions (5 components, 5 methods, 2 EQA materials). The bias between the measurement procedures was unacceptably large in 4/5 tested components. Traceability to reference materials as claimed by the manufacturers did not lead to acceptable harmonization. Adjustment of reference intervals in accordance with method differences and use of commutable EQA samples are not implemented commonly. © 2016 American Association for Clinical Chemistry.

  6. Automatic change detection: does the auditory system use representations of individual stimulus features or gestalts?

    Science.gov (United States)

    Deacon, D; Nousak, J M; Pilotti, M; Ritter, W; Yang, C M

    1998-07-01

    The effects of global and feature-specific probabilities of auditory stimuli were manipulated to determine their effects on the mismatch negativity (MMN) of the human event-related potential. The question of interest was whether the automatic comparison of stimuli indexed by the MMN was performed on representations of individual stimulus features or on gestalt representations of their combined attributes. The design of the study was such that both feature and gestalt representations could have been available to the comparator mechanism generating the MMN. The data were consistent with the interpretation that the MMN was generated following an analysis of stimulus features.

  7. The effects of brief-stimulus presentations in fixed-ratio second-order schedules

    OpenAIRE

    Cohen, Steven L.; Calisto, George

    1981-01-01

    Pigeons' responses were reinforced according to a three-component multiple schedule. In Component 1, key pecks produced food according to a fixed-ratio second-order schedule with fixed-ratio units. Here, a fixed number of fixed-ratio units produced food, and the brief stimulus terminating each unit also accompanied food. Responses in Component 2 produced food on an identical schedule except that the brief stimulus was not paired with food. Component 3 contained a simple fixed-ratio schedule w...

  8. Conditioned Response Evoked by Nicotine Conditioned Stimulus Preferentially Induces c-Fos Expression in Medial Regions of Caudate-Putamen

    OpenAIRE

    Charntikov, Sergios; Tracy, Matthew E; Zhao, Changjiu; Li, Ming; Bevins, Rick A

    2011-01-01

    Nicotine has both unconditioned and conditioned stimulus properties. Conditioned stimulus properties of nicotine may contribute to the tenacity of nicotine addiction. The purpose of this experiment was to use neurohistochemical analysis of rapidly developing c-Fos protein to elucidate neurobiological loci involved in the processing of nicotine as an interoceptive conditioned stimulus (CS). Rats were injected (SC) in an intermixed fashion with saline or nicotine (16 sessions of each) and place...

  9. Cortical processing of near-threshold tactile stimuli in a paired-stimulus paradigm--an MEG study.

    Science.gov (United States)

    Wühle, Anja; Preissl, Hubert; Braun, Christoph

    2011-08-01

    In the present magnetoencephalography study, we applied a paired-stimulus paradigm to study the weak cortical responses evoked by near-threshold tactile prime stimuli by means of their attenuating effect on the cortical responses evoked by subsequently applied above-threshold test stimuli. In stimulus pairs with adequate interstimulus intervals (ISIs), the extent of test stimulus response attenuation is related to the amplitude of prime stimulus responses, and the duration of the attenuating effect indicates how long memory traces of a prime stimulus reside in cortical areas. We hypothesized that the attenuation of test stimulus responses, studied for ISIs of 30, 60 and 150 ms, would provide insight into the temporal dynamics of near-threshold stimulus processing in primary (SI) and secondary somatosensory cortex (SII), and reveal differences in response amplitude due to conscious perception. Attenuation of test stimulus responses in SI was observed for ISIs up to 60 ms, whereas in SII the effect outlasted the ISI of 150 ms. Differences due to conscious perception of the near-threshold stimuli were only observed in SII with stronger attenuation for perceived than for missed near-threshold stimuli. Applying this indirect approach to near-threshold stimulus processing, we could show that the extent and duration of response attenuation is related to prime stimulus processing and differential temporal and functional characteristics of near-threshold stimulus information processing in SI and SII: transient processing of basic stimulus information not sufficient for conscious perception in SI and long-lasting activations involving conscious perception in SII. © 2011 The Authors. European Journal of Neuroscience © 2011 Federation of European Neuroscience Societies and Blackwell Publishing Ltd.

  10. Single drop based-liquid phase microextraction using ionic liquid as extractor solvent for extraction and preconcentration of copper and silver from food and water samples prior to determination by electrothermal atomic absorption spectrometry

    Directory of Open Access Journals (Sweden)

    j Abolhasani

    2013-08-01

    Full Text Available A new single drop micro-extraction method based on ionic liquids was developed for the pre-concentration of ultra-traces of silver and copper prior to its determination by electro-thermal atomic absorption spectrometry (ETAAS. An 8-μL drop of ionic liquid, 1-hexyl-3-methylimidazolium hexafluorophosphate, [C6MIM][PF6], was used for the extraction of silver and copper ions as dithizone complex. Important variables affecting microextraction efficiency and ETAAS signal, such as pyrolysis and atomization temperature, dithizone concentration, extraction time, drop volume and stirring rate were investigated and optimized. Under the optimum experimental conditions, the detection limits (3 s of the method were 4 and 8 ng L-1, for Ag and Cu, respectively and corresponding relative standard deviations (0.1 μg L-1, n = 6 were 4.2% and 4.8%. The developed method was successfully applied to the determination of copper and silver in food and water samples.

  11. Multiresidue determination of pesticides in crop plants by the quick, easy, cheap, effective, rugged, and safe method and ultra-high-performance liquid chromatography tandem mass spectrometry using a calibration based on a single level standard addition in the sample.

    Science.gov (United States)

    Viera, Mariela S; Rizzetti, Tiele M; de Souza, Maiara P; Martins, Manoel L; Prestes, Osmar D; Adaime, Martha B; Zanella, Renato

    2017-12-01

    In this study, a QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) method, optimized by a 2 3 full factorial design, was developed for the determination of 72 pesticides in plant parts of carrot, corn, melon, rice, soy, silage, tobacco, cassava, lettuce and wheat by ultra-high-performance liquid chromatographic tandem mass spectrometry (UHPLC-MS/MS). Considering the complexity of these matrices and the need of use calibration in matrix, a new calibration approach based on single level standard addition in the sample (SLSAS) was proposed in this work and compared with the matrix-matched calibration (MMC), the procedural standard calibration (PSC) and the diluted standard addition calibration (DSAC). All approaches presented satisfactory validation parameters with recoveries from 70 to 120% and relative standard deviations≤20%. SLSAS was the most practical from the evaluated approaches and proved to be an effective way of calibration. Method limit of detection were between 4.8 and 48μgkg -1 and limit of quantification were from 16 to 160μgkg -1 . Method application to different kinds of plants found residues of 20 pesticides that were quantified with z-scores values≤2 in comparison with other calibration approaches. The proposed QuEChERS method combined with UHPLC-MS/MS analysis and using an easy and effective calibration procedure presented satisfactory results for pesticide residues determination in different crop plants and is a good alternative for routine analysis. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. An automated image analysis framework for segmentation and division plane detection of single live Staphylococcus aureus cells which can operate at millisecond sampling time scales using bespoke Slimfield microscopy

    Science.gov (United States)

    Wollman, Adam J. M.; Miller, Helen; Foster, Simon; Leake, Mark C.

    2016-10-01

    Staphylococcus aureus is an important pathogen, giving rise to antimicrobial resistance in cell strains such as Methicillin Resistant S. aureus (MRSA). Here we report an image analysis framework for automated detection and image segmentation of cells in S. aureus cell clusters, and explicit identification of their cell division planes. We use a new combination of several existing analytical tools of image analysis to detect cellular and subcellular morphological features relevant to cell division from millisecond time scale sampled images of live pathogens at a detection precision of single molecules. We demonstrate this approach using a fluorescent reporter GFP fused to the protein EzrA that localises to a mid-cell plane during division and is involved in regulation of cell size and division. This image analysis framework presents a valuable platform from which to study candidate new antimicrobials which target the cell division machinery, but may also have more general application in detecting morphologically complex structures of fluorescently labelled proteins present in clusters of other types of cells.

  13. Rapid and precise determination of Sr and Nd isotopic ratios in geological samples from the same filament loading by thermal ionization mass spectrometry employing a single-step separation scheme.

    Science.gov (United States)

    Li, Chao-Feng; Li, Xian-Hua; Li, Qiu-Li; Guo, Jing-Hui; Li, Xiang-Hui; Yang, Yue-Heng

    2012-05-21

    Thermal ionization mass spectrometry (TIMS) offers the excellent precision and accuracy of the Sr and Nd isotopic ratio analysis for geological samples, but this method is labour intensive, expensive and time-consuming. In this study, a new analytical protocol by TIMS is presented that aims at improving analytical efficiency and cutting down experimental cost. Using the single-step cation exchange resin technique, mixed Sr and rare earth elements (REEs) fractions were separated from matrix and evaporated to dryness. Afterwards, mixed Sr+REEs fractions were dissolved and loaded onto the same Re filament using 1 μL of 2 M HCl. Then, Sr and Nd were sequentially measured without venting using TIMS. In contrast to conventional TIMS methods, the merits of this analytical protocol are its cost- and time-saving adaptations. The applicability of our method is evaluated by replicated measurements of (87)Sr/(86)Sr and (143)Nd/(144)Nd for nine international silicate rock reference materials, spanning a wide range of bulk compositions. The typical internal precision in this study is ca. 0.001% (RSE) for (87)Sr/(86)Sr and (143)Nd/(144)Nd; the analytical results obtained for these standard rocks show a good agreement with reported values, indicating the effectiveness of the proposed method. Copyright © 2012 Elsevier B.V. All rights reserved.

  14. Sampling and estimating recreational use.

    Science.gov (United States)

    Timothy G. Gregoire; Gregory J. Buhyoff

    1999-01-01

    Probability sampling methods applicable to estimate recreational use are presented. Both single- and multiple-access recreation sites are considered. One- and two-stage sampling methods are presented. Estimation of recreational use is presented in a series of examples.

  15. The influence of common stimulus parameters on distortion product otoacoustic emission fine structure.

    Science.gov (United States)

    Johnson, Tiffany A; Baranowski, Lauren G

    2012-01-01

    To determine whether common approaches to setting stimulus parameters influence the depth of fine structure present in the distortion product otoacoustic emission (DPOAE) response. Because the presence of fine structure has been suggested as a possible source of errors, if one of the common parametric approaches results in reduced fine-structure depth, it may be preferred over other approaches. DPOAE responses were recorded in a group of 21 subjects with normal hearing for 1/3-octave intervals surrounding 3 f2s (1, 2, and 4 kHz) at three L2s (30, 45, and 55 dB SPL). For each f2 and L2 combination, L1 and f2/f1 were set according to three commonly used parametric approaches. These included a simple approach, the approach recommended by Kummer et al., and the approach described by Johnson et al. These three approaches primarily differ in the recommended relationship between L1 and L2. For each parametric approach, DPOAE fine structure was evaluated by varying f2 in small steps. Differences in DPOAE level and DPOAE fine-structure depth across f2, L2, and the various stimulus parameters were evaluated using repeated-measures analysis of variance. As expected, significant variations in DPOAE level were observed across the three parametric approaches. For stimulus levels #45 dB SPL, the simple stimuli resulted in lower DPOAE levels than were observed for other approaches. An unexpected finding was that stimulus parameters developed by Johnson et al., which were believed to produce higher DPOAE levels than other approaches, produced the lowest DPOAE levels of the three approaches when f2 = 4 kHz. Significant differences in fine-structure depth were also observed. Greater fine-structure depth was observed with the simple parameters, although this effect was restricted to L2 # 45 dB SPL. When L2 = 55 dB SPL, all three parametric approaches resulted in equivalent fine-structure depth. A significant difference in fine-structure depth across the 3 f2s was also observed. The

  16. Balanced sampling

    NARCIS (Netherlands)

    Brus, D.J.

    2015-01-01

    In balanced sampling a linear relation between the soil property of interest and one or more covariates with known means is exploited in selecting the sampling locations. Recent developments make this sampling design attractive for statistical soil surveys. This paper introduces balanced sampling

  17. Genetic analysis of IQ, processing speed and stimulus-response incongruency effects

    NARCIS (Netherlands)

    Posthuma, D.; Mulder, E.J.C.M.; Boomsma, D.I.; de Geus, E.J.C.

    2002-01-01

    Psychometric IQ (WAIS-III), onset and peak latency of the lateralized readiness potential (LRP), decision time, and accuracy were assessed during an Eriksen Flanker task in a young (149 families) and in an older (122 families) cohort of twins and their siblings. Stimulus-response incongruency

  18. Factors influencing capacity to judge direction of tactile stimulus movement on the face.

    Science.gov (United States)

    Dreyer, D A; Duncan, G H; Wong, C L; Whitsel, B L

    1979-11-01

    The influence of stimulus velocity and traverse length on a subject's ability to indicate direction of brush movement across perioral skin was determined using a forced-choice procedure. The data show that correct identification of brush direction increases with traverse length and is optimal for velocities between 3 and 25 cm/sec.

  19. An Evaluation of Two Stimulus Equivalence Training Sequences on the Emergence of Novel Intraverbals

    Science.gov (United States)

    Zaring-Hinkle, Brittany; Carp, Charlotte Lynn; Lepper, Tracy L.

    2016-01-01

    Researchers have begun to investigate the emergence of novel intraverbals using equivalence-based instruction (EBI) in typically developing children (Carp & Petursdottir, 2012; Pérez-González, Herszlikowicz, & Williams, 2008). We sought to replicate and extend the previous research by investigating two stimulus equivalence training…

  20. Do People Take Stimulus Correlations into Account in Visual Search (Open Source)

    Science.gov (United States)

    2016-03-10

    contribute to bridging the gap between artificial and natural visual search tasks. Introduction Visual target detection in displays consisting of multiple...on an invisible circle centered at the fixation cross, with a radius of 3.2 degrees of visual angle. On each trial, the first stimulus was placed at

  1. Social Stimulus Perception and Self-Evaluation: Effects of Menstrual Cycle Phase.

    Science.gov (United States)

    Alagna, Sheryle W.; Hamilton, Jean A.

    1986-01-01

    Women in different phases of the menstrual cycle were compared to men in their responses to a social interaction stimulus: a videotape depicting a female nurse interacting with a hospitalized patient. Sex differences and cycle-phase differences were found for both affective and cognitive dimensions. Premenstrual women differed from other women,…

  2. Eye Movement Control in Scene Viewing and Reading: Evidence from the Stimulus Onset Delay Paradigm

    Science.gov (United States)

    Luke, Steven G.; Nuthmann, Antje; Henderson, John M.

    2013-01-01

    The present study used the stimulus onset delay paradigm to investigate eye movement control in reading and in scene viewing in a within-participants design. Short onset delays (0, 25, 50, 200, and 350 ms) were chosen to simulate the type of natural processing difficulty encountered in reading and scene viewing. Fixation duration increased…

  3. The unexpected killer: effects of stimulus threat and negative affectivity on inattentional blindness.

    Science.gov (United States)

    Beanland, Vanessa; Tan, Choo Hong; Christensen, Bruce K

    2017-10-25

    Inattentional blindness (IB) occurs when observers fail to detect unexpected objects or events. Despite the adaptive importance of detecting unexpected threats, relatively little research has examined how stimulus threat influences IB. The current study was designed to explore the effects of stimulus threat on IB. Past research has also demonstrated that individuals with elevated negative affectivity have an attentional bias towards threat-related stimuli; therefore, the current study also examined whether state and trait levels of negative affectivity predicted IB for threat-related stimuli. One hundred and eleven participants (87 female, aged 17-40 years) completed an IB task that included both threat-related and neutral unexpected stimuli, while their eye movements were tracked. Participants were significantly more likely to detect the threatening stimulus (19%) than the neutral stimulus (11%) p  =  .035, odds ratio (OR)  =  4.0, 95% confidence interval OR [1.13, 14.17]. Neither state nor trait levels of negative affectivity were significantly associated with IB. These results suggest observers are more likely to detect threat-related unexpected objects, consistent with the threat superiority effect observed in other paradigms. However, most observers were blind to both unexpected stimuli, highlighting the profound influence of expectations and task demands on our ability to perceive even potentially urgent and life-threatening information.

  4. Emotion self-regulation and empathy depend upon longer stimulus exposure.

    Science.gov (United States)

    Ikezawa, Satoru; Corbera, Silvia; Wexler, Bruce E

    2014-10-01

    Observation of others in pain induces positive elevation (pain effect) in late event-related potentials (ERP). This effect is associated with top-down attention regulating processes. It has previously been shown that stimulus exposure duration can affect top-down attentional modulation of response to threat-related stimuli. We investigated the effect of exposure duration on ERP response to others in pain. Two late ERP components, P3 and late positive potentials (LPP), from 18 healthy people were measured while they viewed pictures of hands in painful or neutral situations for either 200 or 500 ms, during two task conditions (pain judgment and counting hands). P3 and LPP pain effects during the pain judgment condition were significantly greater with 500 ms than 200 ms stimulus presentation. Ours is the first study to suggest that engagement of empathy-related self-regulatory processes reflected in late potentials requires longer exposure to the pain-related stimulus. Although this is important information about the relationship between early sensory and subsequent brain processing, and about engagement of self-regulatory processes, the neural basis of this time-dependence remains unclear. It might be important to investigate the relationship between stimulus duration and empathic response in clinical populations where issues of self-regulation, empathic response and speed of information processing exist. © The Author (2013). Published by Oxford University Press. For Permissions, please email: journals.permissions@oup.com.

  5. Development of a Chirp Stimulus PC-Based Auditory Brainstem Response Audiometer

    Directory of Open Access Journals (Sweden)

    Ali AL-Afsaa

    2004-05-01

    Full Text Available Hearing losses during infancy and childhood have many negative future effects and impacts on the child life and productivity. The earlier detection of hearing losses, the earlier medical intervention and then the greater benefit of remediation will be. During this research a PC-based audiometer is designed and, currently, the audiometer prototype is in its final development steps. It is based on the auditory brainstem response (ABR method. Chirp stimuli instead of traditional click stimuli will be used to invoke the ABR signal. The stimulus is designed to synchronize the hair cells movement when it spreads out over the cochlea. In addition to the available hardware utilization (PC and PCI board, the efforts confined to design and implement a hardware prototype and to develop a software package that enables the system to behave as ABR audiometer. By using such a method and chirp stimulus, it is expected to be able to detect hearing impairment (sensorineural in the first few days of the life and conduct hearing test at low frequency of stimulus. Currently, the intended chirp stimulus has been successfully generated and the implemented module is able to amplify a signal (on the order of ABR signal to a recordable level. Moreover, a NI-DAQ data acquisition board has been chosen to implement the PC-prototype interface.

  6. An Appetitive Conditioned Stimulus Enhances Fear Acquisition and Impairs Fear Extinction

    Science.gov (United States)

    Leung, Hiu T.; Holmes, Nathan M.; Westbrook, R. Frederick

    2016-01-01

    Four experiments used between- and within-subject designs to examine appetitive-aversive interactions in rats. Experiments 1 and 2 examined the effect of an excitatory appetitive conditioned stimulus (CS) on acquisition and extinction of conditioned fear. In Experiment 1, a CS shocked in a compound with an appetitive excitor (i.e., a stimulus…

  7. Source memory that encoding was self-referential: the influence of stimulus characteristics.

    Science.gov (United States)

    Durbin, Kelly A; Mitchell, Karen J; Johnson, Marcia K

    2017-10-01

    Decades of research suggest that encoding information with respect to the self improves memory (self-reference effect, SRE) for items (item SRE). The current study focused on how processing information in reference to the self affects source memory for whether an item was self-referentially processed (a source SRE). Participants self-referentially or non-self-referentially encoded words (Experiment 1) or pictures (Experiment 2) that varied in valence (positive, negative, neutral). Relative to non-self-referential processing, self-referential processing enhanced item recognition for all stimulus types (an item SRE), but it only enhanced source memory for positive words (a source SRE). In fact, source memory for negative and neutral pictures was worse for items processed self-referentially than non-self-referentially. Together, the results suggest that item SRE and source SRE (e.g., remembering an item was encoded self-referentially) are not necessarily the same across stimulus types (e.g., words, pictures; positive, negative). While an item SRE may depend on the overall likelihood the item generates any association, the enhancing effects of self-referential processing on source memory for self-referential encoding may depend on how embedded a stimulus becomes in one's self-schema, and that depends, in part, on the stimulus' valence and format. Self-relevance ratings during encoding provide converging evidence for this interpretation.

  8. Inhibition, response mode, and stimulus probability : a comparative event-related potential study

    NARCIS (Netherlands)

    Bruin, K.J.; Wijers, A.A.

    Objectives: In the present study, effects of response mode (finger movement or counting) and stimulus probability on inhibitory processes were studied. Methods: Electroencephalographic activity was registered in a visual go/nogo paradigm. Subjects either responded manually to go stimuli or counted

  9. Involvement of phosphorylated Apis mellifera CREB in gating a honeybee's behavioral response to an external stimulus

    Science.gov (United States)

    Gehring, Katrin B.; Heufelder, Karin; Feige, Janina; Bauer, Paul; Dyck, Yan; Ehrhardt, Lea; Kühnemund, Johannes; Bergmann, Anja; Göbel, Josefine; Isecke, Marlene

    2016-01-01

    The transcription factor cAMP-response element-binding protein (CREB) is involved in neuronal plasticity. Phosphorylation activates CREB and an increased level of phosphorylated CREB is regarded as an indicator of CREB-dependent transcriptional activation. In honeybees (Apis mellifera) we recently demonstrated a particular high abundance of the phosphorylated honeybee CREB homolog (pAmCREB) in the central brain and in a subpopulation of mushroom body neurons. We hypothesize that these high pAmCREB levels are related to learning and memory formation. Here, we tested this hypothesis by analyzing brain pAmCREB levels in classically conditioned bees and bees experiencing unpaired presentations of conditioned stimulus (CS) and unconditioned stimulus (US). We demonstrate that both behavioral protocols display differences in memory formation but do not alter the level of pAmCREB in bee brains directly after training. Nevertheless, we report that bees responding to the CS during unpaired stimulus presentations exhibit higher levels of pAmCREB than nonresponding bees. In addition, Trichostatin A, a histone deacetylase inhibitor that is thought to enhance histone acetylation by CREB-binding protein, increases the bees’ CS responsiveness. We conclude that pAmCREB is involved in gating a bee's behavioral response driven by an external stimulus. PMID:27084927

  10. Poetry Education Research as an Anchorage of Thought: Using Poetry as Interview Stimulus Material

    Science.gov (United States)

    Xerri, Daniel

    2017-01-01

    Interviews in qualitative research may sometimes employ stimulus material as a means of eliciting richer data. However, scant consideration has been given to the use of poetry for this purpose, especially within the field of poetry education research. This article seeks to address the gap in the literature by illustrating how the use of poetry as…

  11. Auditory training alters the physiological detection of stimulus-specific cues in humans.

    Science.gov (United States)

    Tremblay, Kelly L; Shahin, Antoine J; Picton, Terence; Ross, Bernhard

    2009-01-01

    Auditory training alters neural activity in humans but it is unknown if these alterations are specific to the trained cue. The objective of this study was to determine if enhanced cortical activity was specific to the trained voice-onset-time (VOT) stimuli 'mba' and 'ba', or whether it generalized to the control stimulus 'a' that did not contain the trained cue. Thirteen adults were trained to identify a 10ms VOT cue that differentiated the two experimental stimuli. We recorded event-related potentials (ERPs) evoked by three different speech sounds 'ba' 'mba' and 'a' before and after six days of VOT training. The P2 wave increased in amplitude after training for both control and experimental stimuli, but the effects differed between stimulus conditions. Whereas the effects of training on P2 amplitude were greatest in the left hemisphere for the trained stimuli, enhanced P2 activity was seen in both hemispheres for the control stimulus. In addition, subjects with enhanced pre-training N1 amplitudes were more responsive to training and showed the most perceptual improvement. Both stimulus-specific and general effects of training can be measured in humans. An individual's pre-training N1 response might predict their capacity for improvement. N1 and P2 responses can be used to examine physiological correlates of human auditory perceptual learning.

  12. Medial Auditory Thalamic Stimulation as a Conditioned Stimulus for Eyeblink Conditioning in Rats

    Science.gov (United States)

    Campolattaro, Matthew M.; Halverson, Hunter E.; Freeman, John H.

    2007-01-01

    The neural pathways that convey conditioned stimulus (CS) information to the cerebellum during eyeblink conditioning have not been fully delineated. It is well established that pontine mossy fiber inputs to the cerebellum convey CS-related stimulation for different sensory modalities (e.g., auditory, visual, tactile). Less is known about the…

  13. Similarities in the Detection of Stimulus Symmetry by Individuals with and without Mental Retardation.

    Science.gov (United States)

    Carlin, Michael T.; Soraci, Sal A., Jr.

    1993-01-01

    This study found that 10 adolescents with mental retardation processed stimuli varying with respect to symmetry in comparable manner to peers matched for mental age and chronological age. Results argue for the robustness of the symmetry effect across groups differing in intelligence and physically dissimilar stimulus types (checkerboard versus…

  14. Additive and Interactive Effects of Stimulus Degradation: No Challenge for CDP+

    Science.gov (United States)

    Ziegler, Johannes C.; Perry, Conrad; Zorzi, Marco

    2009-01-01

    S. O'Malley and D. Besner (2008) showed that additive effects of stimulus degradation and word frequency in reading aloud occur in the presence of nonwords but not in pure word lists. They argued that this dissociation presents a major challenge to interactive computational models of reading aloud and claimed that no currently implemented model is…

  15. The Developmental Effects of Stimulus Presentation Time on Primacy-Recencency.

    Science.gov (United States)

    Sarver, Gary Steven; Rasbury, Wiley C.

    This study investigated the effects of stimulus presentation rate on primacy-recency effects in children. A modification of the Digit Span task used in the Binet and Wechsler intelligence scales provided the basic memory task administered to 56 male school children in grades kindergarten, second, fourth, and sixth. The specific design required…

  16. Effects of Age and Stimulus Presentation Rate on Immediate and Delayed Recall in Children

    Science.gov (United States)

    Sarver, Gary S.; And Others

    1976-01-01

    The present study was designed to investigate the effects of stimulus presentation rate on recall and primacy-recency effects in children. Results indicated that the traditional interpretation of the primacy effect as reflecting long-term memory store may not be valid. (Author/SB)

  17. Stimulus Disparity and Punisher Control of Human Signal-Detection Performance

    Science.gov (United States)

    Lie, Celia; Alsop, Brent

    2010-01-01

    The present experiment examined the effects of varying stimulus disparity and relative punisher frequencies on signal detection by humans. Participants were placed into one of two groups. Group 3 participants were presented with 1:3 and 3:1 punisher frequency ratios, while Group 11 participants were presented with 1:11 and 11:1 punisher frequency…

  18. Finite element modeling of the neuron-electrode interface: stimulus transfer and geometry

    NARCIS (Netherlands)

    Buitenweg, Jan R.; Rutten, Wim; Marani, Enrico

    1999-01-01

    The relation between stimulus transfer and the geometry of the neuron-electrode interface can not be determined properly using electrical equivalent circuits, since current that flows from the sealing gap through the neuronal membrane is difficult to model in these circuits. Therefore, finite

  19. Can Collateral Behavior Account for Transitions in the Stimulus Control of Speech?

    Science.gov (United States)