40 research outputs found

    Visual Working Memory Recruits Two Functionally Distinct Alpha Rhythms in Posterior Cortex

    Get PDF
    Copyright © 2022 Rodriguez-Larios et al. Oscillatory activity in the human brain is dominated by posterior alpha oscillations (8–14 Hz), which have been shown to be functionally relevant in a wide variety of cognitive tasks. Although posterior alpha oscillations are commonly considered a single oscillator anchored at an individual alpha frequency (∌10 Hz), previous work suggests that individual alpha frequency reflects a spatial mixture of different brain rhythms. In this study, we assess whether independent component analysis (ICA) can disentangle functionally distinct posterior alpha rhythms in the context of visual short-term memory retention. Magnetoencephalography (MEG) was recorded in 33 subjects while performing a visual working memory task. Group analysis at sensor level suggested the existence of a single posterior alpha oscillator that increases in power and decreases in frequency during memory retention. Conversely, single-subject analysis of independent components revealed the existence of two dissociable alpha rhythms: one that increases in power during memory retention (Alpha1) and another one that decreases in power (Alpha2). Alpha1 and Alpha2 rhythms were differentially modulated by the presence of visual distractors (Alpha1 increased in power while Alpha2 decreased) and had an opposite relationship with accuracy (positive for Alpha1 and negative for Alpha2). In addition, Alpha1 rhythms showed a lower peak frequency, a narrower peak width, a greater relative peak amplitude and a more central source than Alpha2 rhythms. Together, our results demonstrate that modulations in posterior alpha oscillations during short-term memory retention reflect the dynamics of at least two distinct brain rhythms with different functions and spatiospectral characteristics.The Netherlands Organisation for Scientific Research (NWO) Vidi Grant 016.Vidi.185.137; National Institutes of Health Grant R01-MH123679

    FCNC Top Quark Decays in Extra Dimensions

    Full text link
    The flavor changing neutral top quark decay t -> c X is computed, where X is a neutral standard model particle, in a extended model with a single extra dimension. The cases for the photon, X= \gamma,andaStandardModelHiggsboson,X=H,areanalyzedindetailinanon−linear, and a Standard Model Higgs boson, X = H, are analyzed in detail in a non-linearR_\xi gauge. We find that the branching ratios can be enhanced by the dynamics originated in the extra dimension. In the limit where 1/R >> ->, we have found Br(t -> c \gamma) \simeq 10^{-10} for 1/R = 0.5 TeV. For the decay t -> c H, we have found Br(t -> cH) \simeq 10^{-10} for a low Higgs mass value. The branching ratios go to zero when 1/R -> \infty.Comment: Accepted to be published in the Europ. Phys. Jour. C; 16 pages, 2 figure

    PGB pair production at LHC and ILC as a probe of the topcolor-assisted technicolor models

    Full text link
    The topcolor-assisted technicolor (TC2) model predicts some light pseudo goldstone bosons (PGBs), which may be accessible at the LHC or ILC. In this work we study the pair productions of the charged or neutral PGBs at the LHC and ILC. For the productions at the LHC we consider the processes proceeding through gluon-gluon fusion and quark-antiquark annihilation, while for the productions at the ILC we consider both the electron-positron collision and the photon-photon collision. We find that in a large part of parameter space the production cross sections at both colliders can be quite large compared with the low standard model backgrounds. Therefore, in future experiments these productions may be detectable and allow for probing TC2 model.Comment: 26 pages, 16 figures. slight changes in the text; notations for curves changed; references adde

    Develop a Study for Geosynthetic Materials for Use in Reducing Pavement Section Thickness

    Get PDF
    P227-21-803Geosynthetics have been used to reinforce aggregate base courses to increase the structural support from the base to the pavement structure. This project aims to develop a study framework to evaluate and quantify the structural benefits under Nevada conditions. To achieve this objective, a five-stage research plan was developed to support a controlled field demonstration, with input regarding design, specification, and standards. This report provides a methodology to determine the expected design life of a specific site with known climate characteristics, subgrade modulus, and traffic. Included are recommendations for the pavement design, testing layout, testing plan, construction guidelines, preliminary implementation plan, and cost estimate
    corecore