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HIgh Frequency Oscillation

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https://www.readbyqxmd.com/read/28636005/mass-mobility-and-ms-n-measurements-of-single-ions-using-charge-detection-mass-spectrometry
#1
Andrew G Elliott, Conner C Harper, Haw-Wei Lin, Evan R Williams
Charge detection mass spectrometry is used to measure the mass, charge, MS(n) and mobility of an individual ion produced by electrospray ionization of a 8 MDa polyethylene glycol sample. The charge detection mass spectrometer is an electrostatic ion trap that uses cone electrodes and a single tube detector and can detect ions for up to the full trapping time of 4.0 s. The time-domain signal induced on the detector tube by a single multiply charged ion can be complex owing to sequential fragmentation of the original precursor ion as well as increasing oscillation frequencies of the single ion owing to collisions with background gas that reduce the kinetic energy of the ion inside the trap...
June 21, 2017: Analyst
https://www.readbyqxmd.com/read/28633830/accompanying-the-frequency-shift-of-the-nonlinear-resonance-of-a-gas-bubble-using-a-dual-frequency-excitation
#2
Matthieu Guédra, Claude Inserra, Bruno Gilles
An asymptotic method is applied to analyze the nonlinear oscillations of a gas bubble driven by a dual-frequency excitation. More specifically, the latter is considered as a combination of two neighboring, incommensurate frequencies and is treated as a nonstationary excitation. This implies that both amplitude and phase of the bubble response are slowly oscillating at the time scale of the frequency difference, thus leading to a regime of aperiodic oscillations. The approximate solution is successfully compared with numerical simulations and reveals the possibility of achieving larger bubble response amplitude compared to the monofrequency excitation for sufficiently high driving pressure and specific values of the frequency difference...
September 2017: Ultrasonics Sonochemistry
https://www.readbyqxmd.com/read/28633817/computational-study-of-state-equation-effect-on-single-acoustic-cavitation-bubble-s-phenomenon
#3
Kaouther Kerboua, Oualid Hamdaoui
Many models have been established to study the evolution of the bubble dynamics and chemical kinetics within a single acoustic cavitation bubble during its oscillation. The content of the bubble is a gas medium that generates the evolution of a chemical mechanism governed by the internal bubble conditions. These gases are described by a state equation, linking the pressure to the volume, temperature and species amounts, and influencing simultaneously the dynamical, the thermal and the mass variation in the cavitation bubble...
September 2017: Ultrasonics Sonochemistry
https://www.readbyqxmd.com/read/28628029/thermopower-and-thermal-conductivity-in-the-weyl-semimetal-nbp
#4
Ulrike Stockert, Ricardo Donizeth Dos Reis, M O Ajeesh, Sarah J Watzman, Marcus Schmidt, Chandra Shekhar, Joseph P Heremans, Claudia Felser, Michael Baenitz, Michael Nicklas
The Weyl semimetal NbP exhibits an extremely large magnetoresistance (MR) and an ultra-high mobility. The large MR originates from a combination of the nearly perfect compensation between electron- and hole-type charge carriers and the high mobility, which is relevant to the topological band structure. In this work we report on temperature- and field-dependent thermopower and thermal conductivity experiments on NbP. Additionally, we carried out complementary heat capacity, magnetization, and electrical resistivity measurements...
June 19, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/28622421/how-to-record-high-frequency-oscillations-in-epilepsy-a-practical-guideline
#5
REVIEW
Maeike Zijlmans, Gregory A Worrell, Matthias Dümpelmann, Thomas Stieglitz, Andrea Barborica, Marcel Heers, Akio Ikeda, Naotaka Usui, Michel Le Van Quyen
OBJECTIVE: Technology for localizing epileptogenic brain regions plays a central role in surgical planning. Recent improvements in acquisition and electrode technology have revealed that high-frequency oscillations (HFOs) within the 80-500 Hz frequency range provide the neurophysiologist with new information about the extent of the epileptogenic tissue in addition to ictal and interictal lower frequency events. Nevertheless, two decades after their discovery there remain questions about HFOs as biomarkers of epileptogenic brain and there use in clinical practice...
June 16, 2017: Epilepsia
https://www.readbyqxmd.com/read/28621838/the-effect-of-compliant-inflow-cannulae-on-the-hemocompatibility-of-rotary-blood-pump-circuits-in-an-in-vitro-model
#6
Jo P Pauls, Deepika Nandakumar, Jarod Horobin, Justin D Prendeville, Michael J Simmonds, John F Fraser, Geoff Tansley, Shaun D Gregory
Rotary blood pumps (RBPs) are used for mechanical circulatory support in heart failure patients but exhibit a reduced response to preload changes, which can lead to ventricular suction events. A passive control system, in the form of a compliant inflow cannula (IC), has been developed to mitigate suction, although this device may cause significant hemolysis. This study compared the incidence of mechanically induced hemolysis of two compliant IC designs (strutted and nonstrutted) with a rigid IC (control) in a blood circulation loop over 90 min...
June 16, 2017: Artificial Organs
https://www.readbyqxmd.com/read/28620295/slow-and-fast-neocortical-oscillations-in-the-senescence-accelerated-mouse-model-samp8
#7
Patricia Castano-Prat, Maria Perez-Zabalza, Lorena Perez-Mendez, Rosa M Escorihuela, Maria V Sanchez-Vives
The senescence-accelerated mouse prone 8 (SAMP8) model is characterized by accelerated, progressive cognitive decline as well as Alzheimer's disease (AD)-like neurodegenerative changes, and resembles the etiology of multicausal, sporadic late-onset/age-related AD in humans. Our aim was to find whether these AD-like pathological features, together with the cognitive deficits present in the SAMP8 strain, are accompanied by disturbances in cortical network activity with respect to control mice (SAM resistance 1, SAMR1) and, if so, how the alterations in cortical activity progress with age...
2017: Frontiers in Aging Neuroscience
https://www.readbyqxmd.com/read/28618494/radiation-dynamics-of-a-cavitation-bubble-in-a-liquid-filled-cavity-surrounded-by-an-elastic-solid
#8
Catherine Drysdale, Alexander A Doinikov, Philippe Marmottant
A specific cavitation phenomenon occurs inside the stems of trees. The internal pressure in tree conduits can drop down to significant negative values, which causes the nucleation of bubbles. The bubbles exhibit high-frequency oscillations just after their nucleation. In the present study, this phenomenon is modeled by taking into account acoustic waves produced by bubble oscillations. A dispersion equation is derived, which is then used to calculate the resonance frequency and the attenuation coefficient of the bubble oscillations...
May 2017: Physical Review. E
https://www.readbyqxmd.com/read/28618295/phase-locked-and-non-phase-locked-eeg-responses-to-pinprick-stimulation-before-and-after-experimentally-induced-secondary-hyperalgesia
#9
Emanuel N van den Broeke, Bart de Vries, Julien Lambert, Diana M Torta, André Mouraux
OBJECTIVE: Pinprick-evoked brain potentials (PEPs) have been proposed as a technique to investigate secondary hyperalgesia and central sensitization in humans. However, the signal-to-noise (SNR) of PEPs is low. Here, using time-frequency analysis, we characterize the phase-locked and non-phase-locked EEG responses to pinprick stimulation, before and after secondary hyperalgesia. METHODS: Secondary hyperalgesia was induced using high-frequency electrical stimulation (HFS) of the left/right forearm skin in 16 volunteers...
May 19, 2017: Clinical Neurophysiology: Official Journal of the International Federation of Clinical Neurophysiology
https://www.readbyqxmd.com/read/28615963/frequency-dependent-changes-in-sensorimotor-and-pain-affective-systems-induced-by-empathy-for-pain
#10
Yoshimasa Motoyama, Katsuya Ogata, Sumio Hoka, Shozo Tobimatsu
BACKGROUND: Empathy for pain helps us to understand the pain of others indirectly. To better comprehend the processing of empathic pain, we report the frequency-dependent modulation of cortical oscillations induced by watching movies depicting pain using high-density electroencephalography (EEG), magnetoencephalography (MEG), and motor evoked potentials (MEP). METHODS: Event-related desynchronization of EEG and MEG was assessed while participants viewed videos of painful (needle) or neutral (cotton swab) situations...
2017: Journal of Pain Research
https://www.readbyqxmd.com/read/28614322/observation-of-robust-flat-band-localization-in-driven-photonic-rhombic-lattices
#11
Sebabrata Mukherjee, Robert R Thomson
We demonstrate that a flat-band state in a quasi-one-dimensional rhombic lattice is robust in the presence of external drivings along the lattice axis. The lattice was formed by periodic arrays of evanescently coupled optical waveguides, and the external drivings were realized by modulating the paths of the waveguides. We excited a superposition of flat-band eigenmodes at the input and observed that this state does not diffract in the presence of static, as well as high-frequency sinusoidal drivings. This robust localization is due to destructive interference of the analogous wavefunction and is associated with the symmetry in the lattice geometry...
June 15, 2017: Optics Letters
https://www.readbyqxmd.com/read/28614321/photonic-microwave-carrier-recovery-using-period-one-nonlinear-dynamics-of-semiconductor-lasers-for-ofdm-rof-coherent-detection
#12
Yu-Han Hung, Jhih-Heng Yan, Kai-Ming Feng, Sheng-Kwang Hwang
This study investigates an all-optical scheme based on period-one (P1) nonlinear dynamics of semiconductor lasers, which regenerates the microwave carrier of an orthogonal frequency division multiplexing radio-over-fiber (OFDM-RoF) signal and uses it as a microwave local oscillator for coherent detection. Through the injection locking established between the OFDM-RoF signal and the P1 dynamics, frequency synchronization with highly preserved phase quality is inherently achieved between the recovered microwave carrier and the microwave carrier of the OFDM-RoF signal...
June 15, 2017: Optics Letters
https://www.readbyqxmd.com/read/28604670/mutual-synchronization-of-spin-torque-nano-oscillators-through-a-long-range-and-tunable-electrical-coupling-scheme
#13
R Lebrun, S Tsunegi, P Bortolotti, H Kubota, A S Jenkins, M Romera, K Yakushiji, A Fukushima, J Grollier, S Yuasa, V Cros
The concept of spin-torque-driven high-frequency magnetization dynamics, allows the potential construction of complex networks of non-linear dynamical nanoscale systems, combining the field of spintronics and the study of non-linear systems. In the few previous demonstrations of synchronization of several spin-torque oscillators, the short-range nature of the magnetic coupling that was used has largely hampered a complete control of the synchronization process. Here we demonstrate the successful mutual synchronization of two spin-torque oscillators with a large separation distance through their long range self-emitted microwave currents...
June 12, 2017: Nature Communications
https://www.readbyqxmd.com/read/28601861/electrical-grounding-improves-vagal-tone-in-preterm-infants
#14
Rohit Passi, Kim K Doheny, Yuri Gordin, Hans Hinssen, Charles Palmer
BACKGROUND: Low vagal tone (VT) is a marker of vulnerability to stress and the risk of developing necrotizing enterocolitis in preterm infants. Electric fields produced by equipment in the neonatal intensive care unit (NICU) induce an electric potential measurable on the skin in reference to ground. An electrical connection to ground reduces the skin potential and improves VT in adults. OBJECTIVES: We aimed to measure the electric field strengths in the NICU environment and to determine if connecting an infant to electrical ground would reduce the skin potential and improve VT...
June 10, 2017: Neonatology
https://www.readbyqxmd.com/read/28600679/resting-state-bold-oscillation-frequency-predicts-vigilance-task-performance-at-both-normal-and-high-environmental-temperatures
#15
Xiaopeng Song, Shaowen Qian, Kai Liu, Shuqin Zhou, Huaiqiu Zhu, Qihong Zou, Yijun Liu, Gang Sun, Jia-Hong Gao
Hyperthermia may impair vigilance functions and lead to slower reaction times (RTs) in the psychomotor vigilance task (PVT) and possibly disturbing cerebral hemodynamic rhythms. To test these hypotheses, we acquired the resting-state BOLD and cerebral blood flow (CBF) data, as well as PVTRTs from 15 participants in two simulated environmental thermal conditions (50 °C/25 °C). We adopted a data-driven method, frequency component analysis, to quantify the mean frequency of the BOLD series of each voxel. Across-subject correlation analysis was employed to detect the brain areas whose BOLD oscillation frequency was correlated with the RTs...
June 9, 2017: Brain Structure & Function
https://www.readbyqxmd.com/read/28597224/high-speed-broadband-monitoring-of-cell-viscoelasticity-in-real-time-shows-myosin-dependent-oscillations
#16
Bo Yan, Juan Ren, Xi Zheng, Yue Liu, Qingze Zou
Study of the dynamic evolutions of cell viscoelasticity is important as during cell activities such as cell metastasis and invasion, the rheological behaviors of the cells also change dynamically, reflecting the biophysical and biochemical connections between the outer cortex and the intracellular structures. Although the time variations of the static modulus of cells have been investigated, few studies have been reported on the dynamic variations of the frequency-dependent viscoelasticity of cells. Measuring and monitoring such dynamic evolutions of cells at nanoscale can be challenging as the measurement needs to meet two objectives inherently contradictory to each other-the measurement must be broadband (to cover a large frequency spectrum) but also rapid (to capture the time-elapsed changes)...
June 8, 2017: Biomechanics and Modeling in Mechanobiology
https://www.readbyqxmd.com/read/28593968/microresonator-based-solitons-for-massively-parallel-coherent-optical-communications
#17
Pablo Marin-Palomo, Juned N Kemal, Maxim Karpov, Arne Kordts, Joerg Pfeifle, Martin H P Pfeiffer, Philipp Trocha, Stefan Wolf, Victor Brasch, Miles H Anderson, Ralf Rosenberger, Kovendhan Vijayan, Wolfgang Freude, Tobias J Kippenberg, Christian Koos
Solitons are waveforms that preserve their shape while propagating, as a result of a balance of dispersion and nonlinearity. Soliton-based data transmission schemes were investigated in the 1980s and showed promise as a way of overcoming the limitations imposed by dispersion of optical fibres. However, these approaches were later abandoned in favour of wavelength-division multiplexing schemes, which are easier to implement and offer improved scalability to higher data rates. Here we show that solitons could make a comeback in optical communications, not as a competitor but as a key element of massively parallel wavelength-division multiplexing...
June 7, 2017: Nature
https://www.readbyqxmd.com/read/28592690/dynamics-of-human-subthalamic-neuron-phase-locking-to-motor-and-sensory-cortical-oscillations-during-movement
#18
Witold J Lipski, Thomas A Wozny, Ahmad Alhourani, Efstathios Kondylis, Robert S Turner, Donald J Crammond, Robert Mark Richardson
Coupled oscillatory activity recorded between sensorimotor regions of the basal ganglia-thalamocortical loop is thought to reflect information transfer relevant to movement. A neuronal firing-rate model of basal ganglia-thalamocortical circuitry, however, has dominated thinking about basal ganglia function for the past three decades, without knowledge of the relationship between basal ganglia single neuron firing and cortical population activity during movement itself. We recorded activity from 34 subthalamic nucleus (STN) neurons, simultaneously with cortical local field potentials and motor output, in eleven subjects with Parkinson's disease (PD) undergoing awake deep brain stimulator lead placement...
June 7, 2017: Journal of Neurophysiology
https://www.readbyqxmd.com/read/28590760/oscillating-ferrofluid-droplet-microrheology-of-liquid-immersed-sessile-droplets
#19
Matilda Backholm, Maja Vuckovac, Jan Schreier, Mika Latikka, Michael Hummel, Markus B Linder, Robin H A Ras
The damped oscillations of liquid-immersed ferrofluid sessile droplets were studied with high-speed imaging experiments and analytical modeling to develop a novel microrheology technique. Droplet oscillations were induced with an external magnetic field, thereby avoiding transients in the resulting vibrational response of the droplet. By following the droplet relaxation with a high-speed camera, the frequency and relaxation time of the damped harmonic oscillations were measured. We extend upon existing analytical theories to describe our liquid-immersed sessile droplet system, and directly quantify the droplet relaxation with the viscosity of the internal and external fluid as well as the interfacial tension between these...
June 14, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28588194/electro-optic-comb-based-real-time-ultra-high-sensitivity-phase-noise-measurement-system-for-high-frequency-microwaves
#20
N Kuse, M E Fermann
Recent progress in ultra low phase noise microwave generation indispensably depends on ultra low phase noise characterization systems. However, achieving high sensitivity currently relies on time consuming averaging via cross correlation, which sometimes even underestimates phase noise because of residual correlations. Moreover, extending high sensitivity phase noise measurements to microwaves beyond 10 GHz is very difficult because of the lack of suitable high frequency microwave components. In this work, we introduce a delayed self-heterodyne method in conjunction with sensitivity enhancement via the use of higher order comb modes from an electro-optic comb for ultra-high sensitivity phase noise measurements...
June 6, 2017: Scientific Reports
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