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HIgh Frequency Oscillation

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https://www.readbyqxmd.com/read/29331056/exploring-the-advantages-of-multiband-fmri-with-simultaneous-eeg-to-investigate-coupling-between-gamma-frequency-neural-activity-and-the-bold-response-in-humans
#1
Makoto Uji, Ross Wilson, Susan T Francis, Karen J Mullinger, Stephen D Mayhew
We established an optimal combination of EEG recording during sparse multiband (MB) fMRI that preserves high-resolution, whole-brain fMRI coverage while enabling broad-band EEG recordings which are uncorrupted by MRI gradient artefacts (GAs). We first determined the safety of simultaneous EEG recording during MB fMRI. Application of MB factor = 4 produced <1°C peak heating of electrode/hardware during 20 min of GE-EPI data acquisition. However, higher SAR sequences require specific safety testing, with greater heating observed using PCASL with MB factor = 4...
January 13, 2018: Human Brain Mapping
https://www.readbyqxmd.com/read/29330496/framing-continental-shelf-waves-in-the-southern-adriatic-sea-a-further-flushing-factor-beyond-dense-water-cascading
#2
Davide Bonaldo, Mirko Orlić, Sandro Carniel
Continental Shelf Waves (CSWs) are oscillatory phenomena migrating along the continental margins, controlled by the interplay of rotation and bathymetric gradients. Here we combine observational data from five moored current meters and high-resolution hydrodynamic model fields for describing the generation and propagation of CSWs along the Southern Adriatic Margin (SAM, eastern Mediterranean Sea), where the possibility of their occurrence has been theoretically hypothesised but not experimentally observed up to now...
January 12, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29329355/when-the-brain-changes-its-mind-oscillatory-dynamics-of-conflict-processing-and-response-switching-in-a-flanker-task-during-alcohol-challenge
#3
Lauren E Beaton, Sheeva Azma, Ksenija Marinkovic
Despite the subjective experience of being in full and deliberate control of our actions, our daily routines rely on a continuous and interactive engagement of sensory evaluation and response preparation streams. They unfold automatically and unconsciously and are seamlessly integrated with cognitive control which is mobilized by stimuli that evoke ambiguity or response conflict. Methods with high spatio-temporal sensitivity are needed to provide insight into the interplay between automatic and controlled processing...
2018: PloS One
https://www.readbyqxmd.com/read/29328310/distribution-of-a-phase-stabilized-100-02-ghz-millimeter-wave-signal-over-a-160-km-optical-fiber-with-4-1-%C3%A3-10-17-instability
#4
Nan Deng, Zhangweiyi Liu, Xiaocheng Wang, Tiantian Fu, Weilin Xie, Yi Dong
We report a long-distance phase-stabilized millimeter-wave distribution over optical fibers, where the optical-link-induced phase noise is compensated with a high-precision photonic-generated millimeter-wave (mm-wave) voltage-controlled oscillator (VCO). The mm-wave VCO is realized based on pre-filtering and re-modulating optical spectral lines of an optical frequency comb (OFC). By adjusting the frequency spacing of the optical spectral lines extracted from the OFC, the phase error of the transmitted optical mm-wave signal can be compensated precisely...
January 8, 2018: Optics Express
https://www.readbyqxmd.com/read/29328169/inverse-synthetic-aperture-ladar-demonstration-system-structure-imaging-processing-and-experiment-result
#5
Ning Wang, Ran Wang, Di Mo, Guangzuo Li, Keshu Zhang, Yirong Wu
A long-distance inverse synthetic aperture LADAR (ISAL) imaging experiment outdoors over 1 km for cooperative targets is demonstrated, which gets a two-dimensional high-resolution image with resolution exceeding 2.5 cm. The system utilizes an electro-optic in-phase and quadrature modulator to output a linear frequency-modulated continuous waveform (LFMCW) with a bandwidth of 6 GHz and pulse repetition frequency (PRF) of 16.7 KHz. For the problem of the coherence of the laser, the effects of the coherent processing interval (CPI) and time delay of the local oscillator (LO) on the coherence are discussed...
January 10, 2018: Applied Optics
https://www.readbyqxmd.com/read/29322095/low-threshold-parametric-oscillation-in-organically-modified-microcavities
#6
Xiaoqin Shen, Rigoberto Castro Beltran, Vinh M Diep, Soheil Soltani, Andrea M Armani
Coherent frequency generators are an enabling platform in basic science and applied technology. Originally reliant on high-power lasers, recently comb generation has been demonstrated in ultrahigh-Q microcavities. The large circulating intensity within the cavity results in strong light-matter interaction, giving rise to Kerr parametric oscillations for comb generation. However, the comb generation threshold is limited by competing nonlinear effects within the cavity material and low intrinsic material Kerr coefficients...
January 2018: Science Advances
https://www.readbyqxmd.com/read/29321646/continuous-wave-y-band-planar-bwo-with-wide-tunable-bandwidth
#7
Hongzhu Xi, Jianguo Wang, Zhaochang He, Gang Zhu, Yue Wang, Hao Wang, Zaigao Chen, Rong Li, Luwei Liu
A high performance continuous-wave (CW) backward wave oscillator (BWO) with planar slow wave structure (SWS) and sheet electron beam in Y-band is presented in this paper. The mode selection is discussed by studying the dispersion curve of SWSs, distributions of the electric field, and particle-in-cell simulation results, showing that the designed BWO operates in the fundamental mode TM11. The planar SWSs are fabricated by using the UV-LIGA technology with the processing error less than 0.003 mm. The electron gun can provide the 2...
January 10, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29321584/the-critical-role-of-phase-difference-in-theta-oscillation-between-bilateral-parietal-cortices-for-visuospatial-working-memory
#8
Philip Tseng, Kai-Chi Iu, Chi-Hung Juan
Visual working memory (VWM) refers to people's ability to maintain and manipulate visual information on line. Its capacity varies between individuals, and neuroimaging studies have suggested a link between one's VWM capacity and theta power in the parietal cortex. However, it is unclear how the parietal cortices communicate with each other in order to support VWM processing. In two experiments we employed transcranial alternate current stimulation (tACS) to use frequency-specific (6 Hz) alternating current to modulate theta oscillation between the left and right parietal cortex with either in-phase (0° difference, Exp 1), anti-phase (180° difference, Exp 2), or sham sinusoidal current stimulation...
January 10, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29317689/high-energy-short-duration-bursts-of-coherent-terahertz-radiation-from-an-embedded-plasma-dipole
#9
Kyu Been Kwon, Teyoun Kang, Hyung Seon Song, Young-Kuk Kim, Bernhard Ersfeld, Dino A Jaroszynski, Min Sup Hur
Emission of radiation from electrons undergoing plasma oscillations (POs) at the plasma frequency has attracted interest because of the existence of intriguing and non-trivial coupling mechanism between the electrostatic PO and the emitted electromagnetic wave. While broadband emission from plasma waves in inhomogeneous plasma is well known, the underlying physics of narrowband emission at the plasma frequency observed in experiments and in solar radio-bursts is obscure. Here we show that a spatially-localized plasma dipole oscillation (PDO) can be generated when electrons are trapped in a moving train of potential wells produced by the ponderomotive force of two slightly detuned laser pulses that collide in plasma and give rise to a burst of quasi-monochromatic radiation...
January 9, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29317186/perturbation-of-theta-gamma-coupling-at-the-temporal-lobe-hinders-verbal-declarative-memory
#10
Gabriel Amador de Lara, Ivan Alekseichuk, Zsolt Turi, Albert Lehr, Andrea Antal, Walter Paulus
BACKGROUND: Phase-amplitude cross-frequency coupling (PAC) is characterized by the modulation of the power of a fast brain oscillation (e.g., gamma) by the phase of a slow rhythm (e.g., theta). PAC in different sub- and neocortical regions is known to underlie effective neural communication and correlates with successful long-term memory formation. OBJECTIVE/HYPOTHESIS: The present work aims to extend earlier observational data, by probing the functional role of theta-gamma PAC in the left temporal cortex in humans during verbal long-term memory encoding...
December 25, 2017: Brain Stimulation
https://www.readbyqxmd.com/read/29315516/strong-coupling-between-slow-oscillations-and-wide-fast-ripples-in-children-with-epileptic-spasms-investigation-of-modulation-index-and-occurrence-rate
#11
Yasushi Iimura, Kevin Jones, Lynne Takada, Itsuki Shimizu, Misaki Koyama, Kyoko Hattori, Yushi Okazawa, Yutaka Nonoda, Eishi Asano, Tomoyuki Akiyama, Cristina Go, Ayako Ochi, O Carter Snead, Elizabeth J Donner, James T Rutka, James M Drake, Hiroshi Otsubo
OBJECTIVE: Epileptic spasms (ES) often become drug-resistant. To reveal the electrophysiological difference between children with ES (ES+) and without ES (ES-), we compared the occurrence rate (OR) of high-frequency oscillations (HFOs) and the modulation index (MI) of coupling between slow and fast oscillations. In ES+, we hypothesized that (1) pathological HFOs are more widely distributed and (2) slow oscillations show stronger coupling with pathological HFOs than in ES-. METHODS: We retrospectively reviewed 24 children with drug-resistant multilobar onset epilepsy, who underwent intracranial video electroencephalography prior to multilobar resections...
January 6, 2018: Epilepsia
https://www.readbyqxmd.com/read/29289423/interpretation-of-seeg-recordings
#12
REVIEW
Fabrice Bartolomei, Anca Nica, Maria Paola Valenti-Hirsch, Claude Adam, Marie Denuelle
The interpretation of SEEG recordings is a crucial step. It must be carried out by an epileptologist/neurophysiologist with sufficient training and qualification in this field. The objectives of the interpretation are to define the brain topography of interictal activities (irritative zone) and the epileptogenic zone, defined as the site of primary organization of ictal discharges. Several patterns of seizure onset are possible, the most typical including fast discharges. The interpretation of the SEEG is based on the recording of spontaneous activity but also on the results of intracerebral electrical stimulation...
December 27, 2017: Neurophysiologie Clinique, Clinical Neurophysiology
https://www.readbyqxmd.com/read/29289186/picosecond-precision-multichannel-autonomous-time-and-frequency-counter
#13
R Szplet, P Kwiatkowski, K Różyc, Z Jachna, T Sondej
This paper presents the design, implementation, and test results of a multichannel time interval and frequency counter developed as a desktop instrument. The counter contains four main functional modules for (1) performing precise measurements, (2) controlling and fast data processing, (3) low-noise power suppling, and (4) supplying a stable reference clock (optional rubidium standard). A fundamental for the counter, the time interval measurement is based on time stamping combined with a period counting and in-period two-stage time interpolation that allows us to achieve wide measurement range (above 1 h), high precision (even better than 4...
December 2017: Review of Scientific Instruments
https://www.readbyqxmd.com/read/29288874/modeling-spike-wave-discharges-by-a-complex-network-of-neuronal-oscillators
#14
Tatiana M Medvedeva, Marina V Sysoeva, Gilles van Luijtelaar, Ilya V Sysoev
PURPOSE: The organization of neural networks and the mechanisms, which generate the highly stereotypical for absence epilepsy spike-wave discharges (SWDs) is heavily debated. Here we describe such a model which can both reproduce the characteristics of SWDs and dynamics of coupling between brain regions, relying mainly on properties of hierarchically organized networks of a large number of neuronal oscillators. MODEL: We used a two level mesoscale model. The first level consists of three structures: the nervus trigeminus serving as an input, the thalamus and the somatosensory cortex; the second level of a group of nearby situated neurons belonging to one of three modeled structures...
December 13, 2017: Neural Networks: the Official Journal of the International Neural Network Society
https://www.readbyqxmd.com/read/29280381/high-mobility-and-hysteresis-free-flexible-oxide-thin-film-transistors-and-circuits-by-using-bilayer-sol-gel-gate-dielectrics
#15
Jeong-Wan Jo, Kwang-Ho Kim, Jaeyoung Kim, Seok-Gyu Ban, Yong-Hoon Kim, Sung Kyu Park
In this paper, we demonstrate high performance and hysteresis-free solution-processed indium-gallium-zinc-oxide (IGZO) thin film transistors (TFTs) and high-frequency-operating 7-stage ring oscillators using a low-temperature photochemically activated Al2O3/ZrO2 bilayer gate dielectric. It was found that the IGZO TFTs with single layer gate dielectrics such as Al2O3, ZrO2 or sodium-doped Al2O3 exhibited large hysteresis, low field-effect mobility or unstable device operation owing to the interfacial/bulk trap states, insufficient band offset or a substantial number of mobile ions present in the gate dielectric layer, respectively...
December 27, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/29277405/transcranial-magnetic-stimulation-of-the-precuneus-enhances-memory-and-neural-activity-in-prodromal-alzheimer-s-disease
#16
Giacomo Koch, Sonia Bonnì, Maria Concetta Pellicciari, Elias P Casula, Matteo Mancini, Romina Esposito, Viviana Ponzo, Silvia Picazio, Francesco Di Lorenzo, Laura Serra, Caterina Motta, Michele Maiella, Camillo Marra, Mara Cercignani, Alessandro Martorana, Carlo Caltagirone, Marco Bozzali
Memory loss is one of the first symptoms of typical Alzheimer's disease (AD), for which there are no effective therapies available. The precuneus (PC) has been recently emphasized as a key area for the memory impairment observed in early AD, likely due to disconnection mechanisms within large-scale networks such as the default mode network (DMN). Using a multimodal approach we investigated in a two-week, randomized, sham-controlled, double-blinded trial the effects of high-frequency repetitive transcranial magnetic stimulation (rTMS) of the PC on cognition, as measured by the Alzheimer Disease Cooperative Study Preclinical Alzheimer Cognitive Composite in 14 patients with early AD (7 females)...
December 19, 2017: NeuroImage
https://www.readbyqxmd.com/read/29276865/high-frequency-oscillatory-ventilation-versus-conventional-mechanical-ventilation-in-pediatric-acute-respiratory-distress-syndrome-a-randomized-controlled-study
#17
Ahmed El-Nawawy, Azza Moustafa, Hassan Heshmat, Ahmed Abouahmed
El-Nawawy A, Moustafa A, Heshmat H, Abouahmed A. High frequency oscillatory ventilation versus conventional mechanical ventilation in pediatric acute respiratory distress syndrome: A randomized controlled study. Turk J Pediatr 2017; 59: 130-143. The aim of this prospective randomized study is to compare the outcomes of the early use of either high frequency oscillation (HFO) or conventional mechanical ventilation (CMV) in patients with pediatric acute respiratory distress syndrome (PARDS). We allocated two hundred PARDS patients over 5 years in 1:1 ratio to either mode...
2017: Turkish Journal of Pediatrics
https://www.readbyqxmd.com/read/29273688/abnormal-beta-power-is-a-hallmark-of-explicit-movement-control-in-functional-movement-disorders
#18
Tiago Teodoro, Anne Marthe Meppelink, Simon Little, Robert Grant, Glenn Nielsen, Antonella Macerollo, Isabel Pareés, Mark J Edwards
OBJECTIVE: To determine whether sensorimotor beta-frequency oscillatory power is raised during motor preparation in patients with functional movement disorders (FMD) and could therefore be a marker of abnormal "body-focused" attention. METHODS: We analyzed motor performance and beta-frequency cortical oscillations during a precued choice reaction time (RT) task with varying cue validity (50% or 95% congruence between preparation and go cues). We compared 21 patients with FMD with 13 healthy controls (HCs)...
December 22, 2017: Neurology
https://www.readbyqxmd.com/read/29259184/early-development-of-network-oscillations-in-the-ferret-visual-cortex
#19
Yuhui Li, Chunxiu Yu, Zhe Charles Zhou, Iain Stitt, Kristin K Sellers, John H Gilmore, Flavio Frohlich
Although oscillations during development have been characterized in a wide range of neural systems, little is known about the interaction between these network oscillations and neuronal spiking, and the interactions among different oscillation frequencies. Here we recorded the spontaneous and visual-elicited local field potential (LFP) and multi-unit activity (MUA) in the visual cortex of freely-moving juvenile ferrets before and after eye-opening. We found that both the spontaneous and visually-elicited LFP power was increased after eye-opening, especially in higher frequency bands (>30 Hz)...
December 19, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29251500/fourier-transform-fluorescence-encoded-infrared-spectroscopy
#20
Joseph Nathanael Mastron, Andrei Tokmakoff
While time-resolved infrared (IR) vibrational spectroscopy provides insight on structural dynamics of solution-phase systems, current techniques are limited to high concentrations. Fluorescence-encoded infrared spectroscopy (FEIR) can be used to encode IR-driven vibrational excitations into excited electronic states that fluoresce, which can be detected at lower concentrations than a coherently-detected IR signal. Here, we report on the development of Fourier transform FEIR as an alternate approach for high sensitivity IR spectroscopy...
December 18, 2017: Journal of Physical Chemistry. A
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