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High frequency oscillations

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https://www.readbyqxmd.com/read/28739525/state-dependent-alpha-peak-frequency-shifts-experimental-evidence-potential-mechanisms-and-functional-implications
#1
REVIEW
Andreas Mierau, Wolfgang Klimesch, Jérémie Lefebvre
Neural populations produce complex oscillatory patterns thought to implement brain function. The dominant rhythm in the healthy adult human brain is formed by alpha oscillations with a typical power peak most commonly found between 9 and 11 Hz. This alpha peak frequency has been repeatedly discussed as a highly heritable and stable neurophysiological "trait" marker reflecting anatomical properties of the brain, and individuals' general cognitive capacity. However, growing evidence suggests that the alpha peak frequency is highly volatile at shorter time scales, dependent on the individuals' "state"...
July 21, 2017: Neuroscience
https://www.readbyqxmd.com/read/28738697/reduction-of-heart-rate-variability-in-hypertensive-elderly
#2
Paulo Evaristo de Andrade, Joice Anaize Tonon do Amaral, Laércio da Silva Paiva, Fernando Adami, Juliana Zangirolami Raimudo, Vitor Engrácia Valenti, Luiz Carlos de Abreu, Rodrigo Daminello Raimundo
INTRODUCTION: The elderly population grows globally every day, and along with it the incidence of high blood pressure also grows, following these data scientists seek tools to improve the health of this population, a widely used tool for assessing cardiovascular function is the heart rate variability(HRV), that is a mecanism that allows the investigation of oscillations in the intervals between consecutive heart beats (RR intervals). There are already studies on the autonomic nervous system in the elderly population, however, these studies investigated normotensive patients and there is little research in hypertensive patients...
July 24, 2017: Blood Pressure
https://www.readbyqxmd.com/read/28738310/postural-response-to-predictable-and-nonpredictable-visual-flow-in-children-and-adults
#3
Mark A Schmuckler
Children's (3-5years) and adults' postural reactions to different conditions of visual flow information varying in its frequency content was examined using a moving room apparatus. Both groups experienced four conditions of visual input: low-frequency (0.20Hz) visual oscillations, high-frequency (0.60Hz) oscillations, multifrequency nonpredictable visual input, and no imposed visual information. Analyses of the frequency content of anterior-posterior (AP) sway revealed that postural reactions to the single-frequency conditions replicated previous findings; children were responsive to low- and high-frequency oscillations, whereas adults were responsive to low-frequency information...
July 21, 2017: Journal of Experimental Child Psychology
https://www.readbyqxmd.com/read/28733314/effects-of-an-airway-clearance-device-on-inflammation-bacteriology-and-mucus-transport-in-bronchiectasis
#4
Joana Tambascio, Hugo Celso Dutra de Souza, Roberto Martinez, José Antônio Baddini-Martinez, Peter John Barnes, Ada Clarice Gastaldi
BACKGROUND: Bronchiectasis is characterized by abnormal and permanent dilation of the bronchi, caused by the perpetuation of inflammation and impairment of mucociliary clearance. Physiotherapy techniques can help to decrease the retention of respiratory secretions. The flutter valve combines high-frequency oscillation and positive expiratory pressure to facilitate the removal of secretions. We evaluated the effects of the flutter valve on sputum inflammation, microbiology, and transport of respiratory secretions in patients with bronchiectasis...
August 2017: Respiratory Care
https://www.readbyqxmd.com/read/28729421/the-small-g-protein-ras2-is-involved-in-the-metabolic-compensation-of-the-circadian-clock-in-the-circadian-model-neurospora-crassa
#5
Norbert Gyöngyösi, Anita Szöke, Krisztina Ella, Krisztina Káldi
Accumulating evidence from both experimental and clinical investigations indicate a tight interaction between metabolism and circadian timekeeping; however, knowledge of the underlying mechanism is still incomplete. Metabolic compensation allows circadian oscillators to run with a constant speed at different substrate levels and therefore is a substantial criterion of a robust rhythm in a changing environment. Because previous data have suggested a central role of RAS2-mediated signaling in the adaptation of yeast to different nutritional environments, we examined the involvement of RAS2 in the metabolic regulation of the clock in the circadian model organism Neurospora crassa...
July 20, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28729115/arousal-and-drug-abuse
#6
REVIEW
Francisco J Urbano, Verónica Bisagno, Edgar Garcia-Rill
The reticular activating system (RAS) is not an amorphous region but distinct nuclei with specific membrane properties that dictate their firing during waking and sleep. The locus coeruleus and raphe nucleus fire during waking and slow wave sleep, with the pedunculopontine nucleus (PPN) firing during both waking and REM sleep, the states manifesting arousal-related EEG activity. Two important discoveries in the PPN in the last 10 years are, 1) that some PPN cells are electrically coupled, and 2) every PPN cell manifests high threshold calcium channels that allow them to oscillate at beta/gamma band frequencies...
July 17, 2017: Behavioural Brain Research
https://www.readbyqxmd.com/read/28728081/brain-state-dependent-recruitment-of-high-frequency-oscillations-in-the-human-hippocampus
#7
Pablo Billeke, Tomas Ossandon, Marcelo Stockle, Marcela Perrone-Bertolotti, Philippe Kahane, Jean-Philippe Lachaux, Pablo Fuentealba
Ripples are high-frequency bouts of coordinated hippocampal activity believed to be crucial for information transfer and memory formation. We used intracortical macroelectrodes to record neural activity in the human hippocampus of awake subjects undergoing surgical treatment for refractory epilepsy and distinguished two populations of ripple episodes based on their frequency spectrum. The phase-coupling of one population, slow ripples (90-110 Hz), to cortical delta oscillations was differentially modulated by cognitive task; whereas the second population, fast ripples (130-170 Hz), was not seemingly correlated to local neural activity...
June 23, 2017: Cortex; a Journal Devoted to the Study of the Nervous System and Behavior
https://www.readbyqxmd.com/read/28726385/low-temperature-post-functionalization-of-highly-conductive-oxide-thin-films-toward-solution-based-large-scale-electronics
#8
Seok-Gyu Ban, Kyung-Tae Kim, Byung Doo Choi, Jeong-Wan Jo, Yong-Hoon Kim, Antonio Facchetti, Myung-Gil Kim, Sung Kyu Park
Although transparent conducting oxides (TCOs) have played a key role in a wide range of solid-state electronics from conventional optoelectronics to emerging electronic systems, the processing temperature and conductivity of solution-processed materials seem to be far exceeding the thermal limitations of soft materials and insufficient for high-perfomance large-area systems, respectively. Here, we report a strategy to form highly conductive and scalable solution-processed oxide materials and their successful translation into large-area electronic applications, which is enabled by photo-assisted post-functionalization at low-temperature...
July 20, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28724996/dynamics-of-high-viscosity-contrast-confluent-microfluidic-flows
#9
Michael E Kurdzinski, Berrak Gol, Aaron Co Hee, Peter Thurgood, Jiu Yang Zhu, Phred Petersen, Arnan Mitchell, Khashayar Khoshmanesh
The laminar nature of microfluidic flows is most elegantly demonstrated via the confluence of two fluids forming two stable parallel flows within a single channel meeting at a highly stable interface. However, maintenance of laminar conditions can become complicated when there is a large viscosity contrast between the neighbouring flows leading to unique instability patterns along their interface. Here, we study the dynamics of high viscosity contrast confluent flows - specifically a core flow made of highly viscous glycerol confined by sheath flows made of water within a microfluidic flow focusing system...
July 19, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28718301/web-addiction-in-the-brain-cortical-oscillations-autonomic-activity-and-behavioral-measures
#10
Michela Balconi, Salvatore Campanella, Roberta Finocchiaro
Background and aims Internet addiction (IA) was recently defined as a disorder tagging both the impulse control and the reward systems. Specifically, inhibitory deficits and reward bias were considered highly relevant in IA. This research aims to examine the electrophysiological correlates and autonomic activity [skin conductance response (SCR) and heart rate] in two groups of young subjects (N = 25), with high or low IA profile [tested by the Internet Addiction Test (IAT)], with specific reference to gambling behavior...
July 18, 2017: Journal of Behavioral Addictions
https://www.readbyqxmd.com/read/28714094/selective-high-frequency-mechanical-actuation-driven-by-the-vo2-electronic-instability
#11
Nicola Manca, Luca Pellegrino, Teruo Kanki, Warner J Venstra, Giordano Mattoni, Yoshiyuki Higuchi, Hidekazu Tanaka, Andrea D Caviglia, Daniele Marré
Relaxation oscillators consist of periodic variations of a physical quantity triggered by a static excitation. They are a typical consequence of nonlinear dynamics and can be observed in a variety of systems. VO2 is a correlated oxide with a solid-state phase transition above room temperature, where both electrical resistance and lattice parameters undergo a drastic change in a narrow temperature range. This strong nonlinear response allows to realize spontaneous electrical oscillations in the megahertz range under a DC voltage bias...
July 17, 2017: Advanced Materials
https://www.readbyqxmd.com/read/28709992/time-dependent-evolution-of-seizures-in-a-model-of-mesial-temporal-lobe-epilepsy
#12
Charles Behr, Maxime Lévesque, Thomas Stroh, Massimo Avoli
Low-voltage fast (LVF) and hypersynchronous (HYP) - onset seizures occur in the EEG obtained with depth electrodes from mesial temporal lobe epilepsy (MTLE) patients and animal models. In epileptic rats analyzed up to approximately two weeks after pilocarpine-induced status epilepticus (SE), these patterns are associated with specific high-frequency oscillation (HFO) content: ripples (80-200Hz) or fast-ripples (250-500Hz) predominate in LVF or HYP seizures, respectively. To establish whether these features change over the course of the disease, we recorded the EEG from the hippocampal CA3 subfield, subiculum, entorhinal cortex and dentate gyrus in two groups of pilocarpine-treated rats: the "early stage group" (n=8) was analyzed from day 3 to 20 post-SE while the "late stage group" (n=7) was studied from day 27 to 53 post-SE...
July 12, 2017: Neurobiology of Disease
https://www.readbyqxmd.com/read/28708140/wideband-tunable-opto-electronic-oscillator-based-on-frequency-translation
#13
Zeev Tamir, Asher Meltzer, Moshe Horowitz
We demonstrate a new method to obtain a widely tunable low phase-noise opto-electronic oscillator (OEO), based on translating the OEO signal into a lower intermediate frequency (IF) signal. The OEO signal is downconverted to IF by using a local oscillator (LO) signal, filtered by a high-Q filter; its frequency is then upconverted back into the high OEO frequency. The combination of a narrowband filter at a fixed central frequency with a tunable LO forms a tunable high-Q bandpass filter (BPF) that can be used to change the OEO frequency over a broad frequency region...
July 15, 2017: Optics Letters
https://www.readbyqxmd.com/read/28702575/multi-walled-boron-nitride-nanotubes-as-self-excited-launchers
#14
Yifan Li, Yi Zhou, Yan Wu, Chengchi Huang, Long Wang, Xuyan Zhou, Zhenyang Zhao, Hui Li
A self-excited launcher consisting of multi-walled boron nitride nanotubes (BNNTs) has been investigated using molecular dynamics simulation. The results show that, after a period of high frequency oscillation, the innermost BNNT can be spontaneously ejected along its central axis at a relatively fast speed. The launching is caused by the energy transfer between the nanotubes and without absorbing energy from the external environment. Most self-excited launchers could launch their innermost nanotube, although an inappropriate structure of the nanotubes contributes to a blocked or failed launch...
July 27, 2017: Nanoscale
https://www.readbyqxmd.com/read/28702346/automatic-detection-and-visualisation-of-meg-ripple-oscillations-in-epilepsy
#15
Nicole van Klink, Frank van Rosmalen, Jukka Nenonen, Sergey Burnos, Liisa Helle, Samu Taulu, Paul Lawrence Furlong, Maeike Zijlmans, Arjan Hillebrand
High frequency oscillations (HFOs, 80-500 Hz) in invasive EEG are a biomarker for the epileptic focus. Ripples (80-250 Hz) have also been identified in non-invasive MEG, yet detection is impeded by noise, their low occurrence rates, and the workload of visual analysis. We propose a method that identifies ripples in MEG through noise reduction, beamforming and automatic detection with minimal user effort. We analysed 15 min of presurgical resting-state interictal MEG data of 25 patients with epilepsy. The MEG signal-to-noise was improved by using a cross-validation signal space separation method, and by calculating ~ 2400 beamformer-based virtual sensors in the grey matter...
2017: NeuroImage: Clinical
https://www.readbyqxmd.com/read/28700096/peak-alpha-frequency-is-a-neural-marker-of-cognitive-function-across-the-autism-spectrum
#16
Abigail Dickinson, Charlotte DiStefano, Damla Senturk, Shafali Spurling Jeste
Cognitive function varies substantially and serves as a key predictor of outcome and response to intervention in autism spectrum disorder (ASD), yet we know little about the neurobiological mechanisms that underlie cognitive function in children with ASD. The dynamics of neuronal oscillations in the alpha range (6-12 Hz) are associated with cognition in typical development. Peak alpha frequency is also highly sensitive to developmental changes in neural networks which underlie cognitive function, and therefore it holds promise as a developmentally-sensitive neural marker of cognitive function in ASD...
July 12, 2017: European Journal of Neuroscience
https://www.readbyqxmd.com/read/28699704/aberrant-blood-oxygen-level-dependent-signal-oscillations-across-frequency-bands-characterize-the-alcoholic-brain
#17
Jui-Yang Hong, Eva M Müller-Oehring, Adolf Pfefferbaum, Edith V Sullivan, Dongjin Kwon, Tilman Schulte
Chronic alcoholism is associated with widespread regional differences from controls in brain activity and connectivity dynamics measured by blood-oxygen-level-dependent (BOLD) signals. Identification of alcoholism-related neurofunctional power dynamics using functional magnetic resonance imaging (fMRI) that relate to cognition and behavior may serve as biomarkers of alcoholism. Previously, resting-state fMRI studies examined BOLD signals at a single low-frequency (LF) bandwidth. BOLD signals, however, oscillate systematically at different frequencies and are organized in a resting brain where LF oscillation facilitates long-distance communication between regions across cortical regions, whereas high-frequency (HF) oscillation occurs in closely localized, subcortical areas...
July 12, 2017: Addiction Biology
https://www.readbyqxmd.com/read/28696761/parametric-oscillation-frequency-mixing-and-injection-locking-of-strongly-coupled-nanomechanical-resonator-modes
#18
Maximilian J Seitner, Mehdi Abdi, Alessandro Ridolfo, Michael J Hartmann, Eva M Weig
We study locking phenomena of two strongly coupled, high quality factor nanomechanical resonator modes to a common parametric drive at a single drive frequency in different parametric driving regimes. By controlled dielectric gradient forces we tune the resonance frequencies of the flexural in-plane and out-of-plane oscillation of the high stress silicon nitride string through their mutual avoided crossing. For the case of the strong common parametric drive signal-idler generation via nondegenerate parametric two-mode oscillation is observed...
June 23, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28696734/coherent-transfer-between-low-angular-momentum-and-circular-rydberg-states
#19
A Signoles, E K Dietsche, A Facon, D Grosso, S Haroche, J M Raimond, M Brune, S Gleyzes
We realize a coherent transfer between a laser-accessible low-angular-momentum Rydberg state and the circular Rydberg level with maximal angular momentum. It is induced by a radio frequency field with a high-purity σ^{+} polarization resonant on Stark transitions inside the hydrogenic Rydberg manifold. We observe over a few microseconds more than 20 coherent Rabi oscillations between the initial Rydberg state and the circular level. We characterize these many-Rydberg-level oscillations and find them in perfect agreement with a simple model...
June 23, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28694489/high-frequency-components-of-hemodynamic-shear-stress-profiles-are-a-major-determinant-of-shear-mediated-platelet-activation-in-therapeutic-blood-recirculating-devices
#20
Filippo Consolo, Jawaad Sheriff, Silvia Gorla, Nicolò Magri, Danny Bluestein, Federico Pappalardo, Marvin J Slepian, Gianfranco B Fiore, Alberto Redaelli
We systematically analyzed the relative contributions of frequency component elements of hemodynamic shear stress waveforms encountered in cardiovascular blood recirculating devices as to overall platelet activation over time. We demonstrated that high frequency oscillations are the major determinants for priming, triggering and yielding activated "prothrombotic behavior" for stimulated platelets, even if the imparted shear stress has low magnitude and brief exposure time. Conversely, the low frequency components of the stress signal, with limited oscillations over time, did not induce significant activation, despite being of high magnitude and/or exposure time...
July 10, 2017: Scientific Reports
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