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HIgh Frequency Oscillation

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https://www.readbyqxmd.com/read/29791397/high-repetition-rate-single-frequency-ho-yag-mopa-system
#1
Yixuan Zhang, Chunqing Gao, Qing Wang, QuanXin Na, Mingwei Gao, Meng Zhang, Shuai Huang
A stable, 2.09 μm single-frequency Ho:YAG master oscillator and power amplifier (MOPA) system at a pulse repetition frequency of 1.25 kHz is demonstrated. The maximum output energy of the single-frequency injection-seeded laser is 13.76 mJ, and the corresponding pulse width is 178.9 ns. The seed laser is a continuous-wave Ho:YAG non-planar ring oscillator laser. The half-width of the pulse spectrum is measured to be 2.65 MHz by using the heterodyne technique, which is about 1.06 times Fourier transform limited...
May 20, 2018: Applied Optics
https://www.readbyqxmd.com/read/29781566/the-5-ht7-receptor-is-up-regulated-in-onuf-s-nucleus-in-rats-with-chronic-spinal-cord-injury
#2
Jianshu Ni, Nailong Cao, Xiaohu Wang, Changsheng Zhan, Jiemin Si, Baojun Gu, Karl-Erik Andersson
OBJECTIVES: To examine the effect of intrathecal 5-HT7 agonist administration on voiding function in urethane-anesthetized rat, and the change of 5-HT7 receptor expression in lumbosacral cord Onuf's nucleus after SCI. MATERIALS AND METHODS: Thirty-two female Sprague-Dawley (SD) rats were divided into spinally intact (SI) group and SCI group (n=16 each). Eight weeks after transection, half of the rats underwent continuous cystometry under urethane anesthetization, and the 5-HT7 selective agonist LP44 was given intrathecally...
May 21, 2018: BJU International
https://www.readbyqxmd.com/read/29778070/high-intensity-binge-drinking-is-associated-with-alterations-in-spontaneous-neural-oscillations-in-young-adults
#3
Rifqi O Affan, Siyuan Huang, Stephen M Cruz, Lee A Holcomb, Edward Nguyen, Ksenija Marinkovic
Heavy episodic alcohol consumption (also termed binge drinking) contributes to a wide range of health and cognitive deficits, but the associated brain-based indices are poorly understood. The current study used electroencephalography (EEG) to examine spontaneous neural oscillations in young adults as a function of quantity, frequency, and the pattern of their alcohol consumption. Sixty-one young adults (23.4 ± 3.4 years of age) were assigned to binge drinking (BD) and light drinking (LD) groups that were equated on gender, race/ethnic identity, age, educational background, and family history of alcoholism...
January 8, 2018: Alcohol
https://www.readbyqxmd.com/read/29777479/frontal-delta-beta-cross-frequency-coupling-in-high-and-low-social-anxiety-an-index-of-stress-regulation
#4
Eefje S Poppelaars, Anita Harrewijn, P Michiel Westenberg, Melle J W van der Molen
Cross-frequency coupling (CFC) between frontal delta (1-4 Hz) and beta (14-30 Hz) oscillations has been suggested as a candidate neural correlate of social anxiety disorder, a disorder characterized by fear and avoidance of social and performance situations. Prior studies have used amplitude-amplitude correlation (AAC) as a CFC measure and hypothesized it as a candidate neural mechanism of affective control. However, using this metric has yielded inconsistent results regarding the direction of CFC, and the functional significance of coupling strength is uncertain...
May 17, 2018: Cognitive, Affective & Behavioral Neuroscience
https://www.readbyqxmd.com/read/29776095/optimal-entrainment-of-circadian-clocks-in-the-presence-of-noise
#5
Michele Monti, David K Lubensky, Pieter Rein Ten Wolde
Circadian clocks are biochemical oscillators that allow organisms to estimate the time of the day. These oscillators are inherently noisy due to the discrete nature of the reactants and the stochastic character of their interactions. To keep these oscillators in sync with the daily day-night rhythm in the presence of noise, circadian clocks must be coupled to the dark-light cycle. In this paper, we study the entrainment of phase oscillators as a function of the intrinsic noise in the system. Using stochastic simulations, we compute the optimal coupling strength, intrinsic frequency, and shape of the phase-response curve, that maximize the mutual information between the phase of the clock and time...
March 2018: Physical Review. E
https://www.readbyqxmd.com/read/29775365/raman-spectral-band-oscillations-in-large-graphene-bubbles
#6
Yuan Huang, Xiao Wang, Xu Zhang, Xianjue Chen, Baowen Li, Bin Wang, Ming Huang, Chongyang Zhu, Xuewei Zhang, Wolfgang S Bacsa, Feng Ding, Rodney S Ruoff
Raman spectra of large graphene bubbles showed size-dependent oscillations in spectral intensity and frequency, which originate from optical standing waves formed in the vicinity of the graphene surface. At a high laser power, local heating can lead to oscillations in the Raman frequency and also create a temperature gradient in the bubble. Based on Raman data, the temperature distribution within the graphene bubble was calculated, and it is shown that the heating effect of the laser is reduced when moving from the center of a bubble to its edge...
May 4, 2018: Physical Review Letters
https://www.readbyqxmd.com/read/29772381/high-gamma-activity-in-the-human-hippocampus-and-parahippocampus-during-inter-trial-rest-periods-of-a-virtual-navigation-task
#7
Yi Pu, Brian R Cornwell, Douglas Cheyne, Blake W Johnson
In rodents, hippocampal cell assemblies formed during learning of a navigation task are observed to re-emerge during resting (offline) periods, accompanied by high-frequency oscillations (HFOs). This phenomenon is believed to reflect mechanisms for strengthening newly-formed memory traces. Using magnetoencephalography recordings and a beamforming source location algorithm (synthetic aperture magnetometry), we investigated high-gamma (80-140 Hz) oscillations in the hippocampal region in 18 human participants during inter-trial rest periods in a virtual navigation task...
May 14, 2018: NeuroImage
https://www.readbyqxmd.com/read/29770273/westwards-and-northwards-dispersal-of-triosteum-himalayanum-caprifoliaceae-from-the-hengduan-mountains-region-based-on-chloroplast-dna-phylogeography
#8
Hai-Rui Liu, Qing-Bo Gao, Fa-Qi Zhang, Gulzar Khan, Shi-Long Chen
The varying topography and environment that resulted from paleoorogeny and climate fluctuations of the Himalaya-Hengduan Mountains (HHM) areas had a considerable impact on the evolution of biota during the Quaternary. To understand the phylogeographic pattern and historical dynamics of Triosteum himalayanum (Caprifoliaceae), we sequenced three chloroplast DNA fragments ( rbcL-accD , rps15-ycf1 , and trnH-psbA ) from 238 individuals representing 20 populations. Nineteen haplotypes (H1-H19) were identified based on 23 single-site mutations and eight indels...
2018: PeerJ
https://www.readbyqxmd.com/read/29765805/artifacts-in-time-resolved-kelvin-probe-force-microscopy
#9
Sascha Sadewasser, Nicoleta Nicoara, Santiago D Solares
Kelvin probe force microscopy (KPFM) has been used for the characterization of metals, insulators, and semiconducting materials on the nanometer scale. Especially in semiconductors, the charge dynamics are of high interest. Recently, several techniques for time-resolved measurements with time resolution down to picoseconds have been developed, many times using a modulated excitation signal, e.g., light modulation or bias modulation that induces changes in the charge carrier distribution. For fast modulation frequencies, the KPFM controller measures an average surface potential, which contains information about the involved charge carrier dynamics...
2018: Beilstein Journal of Nanotechnology
https://www.readbyqxmd.com/read/29762573/multimilliwatt-tunable-continuous-wave-mid-infrared-generation-across-4-6-4-7-%C3%AE-m-based-on-orientation-patterned-gallium-phosphide
#10
Kavita Devi, A Padhye, P G Schunemann, M Ebrahim-Zadeh
We report the generation of tunable continuous-wave (cw) mid-infrared (mid-IR) radiation across 4608-4694 nm using the new nonlinear material, orientation-patterned gallium phosphide (OP-GaP). By exploiting difference-frequency mixing between a cw Tm-fiber laser and a home-built cw optical parametric oscillator in a 40-mm-long crystal, we have generated up to 43 mW of cw output power, with >30  mW across >95% of the mid-IR tuning range. The output at 4608 nm exhibits high beam quality with a passive power stability of 2...
May 15, 2018: Optics Letters
https://www.readbyqxmd.com/read/29760664/reduced-renal-mass-salt-sensitive-hypertension-is-resistant-to-renal-denervation
#11
Ionut Tudorancea, Thomas E Lohmeier, Barbara T Alexander, Dragos Pieptu, Dragomir N Serban, Radu Iliescu
Aim: Activation of the sympathetic nervous system is common in resistant hypertension (RHT) and also in chronic kidney disease (CKD), a prevalent condition among resistant hypertensives. However, renal nerve ablation lowers blood pressure (BP) only in some patients with RHT. The influence of loss of nephrons per se on the antihypertensive response to renal denervation (RDNx) is unclear and was the focus of this study. Methods: Systemic hemodynamics and sympathetically mediated low frequency oscillations of systolic BP were determined continuously from telemetrically acquired BP recordings in rats before and after surgical excision of ∼80% of renal mass and subsequent RDNx...
2018: Frontiers in Physiology
https://www.readbyqxmd.com/read/29760182/alternating-modulation-of-subthalamic-nucleus-beta-oscillations-during-stepping
#12
Petra Fischer, Chiung Chu Chen, Ya Ju Chang, Chien-Hung Yeh, Alek Pogosyan, Damian M Herz, Binith Cheeran, Alexander L Green, Tipu Z Aziz, Jonathan Hyam, Simon Little, Thomas Foltynie, Patricia Limousin, Ludvic Zrinzo, Harutomo Hasegawa, Michael Samuel, Keyoumars Ashkan, Peter Brown, Huiling Tan
Gait disturbances in Parkinson's disease are commonly refractory to current treatment options and majorly impair patient's quality of life. Auditory cues facilitate gait and prevent motor blocks. We investigated how neural dynamics in the human subthalamic nucleus of Parkinsons's disease patients (14 male, 2 female) vary during stepping and whether rhythmic auditory cues enhance the observed modulation. Oscillations in the beta band were suppressed after ipsilateral heel strikes, when the contralateral foot had to be raised, and re-appeared after contralateral heel strikes, when the contralateral foot rested on the floor...
May 14, 2018: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/29758724/nonlinear-oscillatory-rarefied-gas-flow-inside-a-rectangular-cavity
#13
Peng Wang, Lianhua Zhu, Wei Su, Lei Wu, Yonghao Zhang
The nonlinear oscillation of rarefied gas flow inside a two-dimensional rectangular cavity is investigated on the basis of the Shakhov kinetic equation. The gas dynamics, heat transfer, and damping force are studied numerically via the discrete unified gas-kinetic scheme for a wide range of parameters, including gas rarefaction, cavity aspect ratio, and oscillation frequency. Contrary to the linear oscillation where the velocity, temperature, and heat flux are symmetrical and oscillate with the same frequency as the oscillating lid, flow properties in nonlinear oscillatory cases turn out to be asymmetrical, and second-harmonic oscillation of the temperature field is observed...
April 2018: Physical Review. E
https://www.readbyqxmd.com/read/29756834/anomalous-change-in-the-de-haas-van-alphen-oscillations-of-cecoin_-5-at-ultralow-temperatures
#14
Hiroaki Shishido, Shogo Yamada, Kaori Sugii, Masaaki Shimozawa, Youichi Yanase, Minoru Yamashita
We perform de Haas-van Alphen (dHvA) measurements of the heavy-fermion superconductor CeCoIn_{5} down to 2 mK above the upper critical field. We find that the dHvA amplitudes show an anomalous suppression, concomitantly with a shift of the dHvA frequency, below the transition temperature T_{n}=20  mK. We suggest that the change is owing to magnetic breakdown caused by a field-induced antiferromagnetic (AFM) state emerging below T_{n}, revealing the origin of the field-induced quantum critical point (QCP) in CeCoIn_{5}...
April 27, 2018: Physical Review Letters
https://www.readbyqxmd.com/read/29747149/the-analysis-of-eeg-coherence-reflects-middle-childhood-differences-in-mathematical-achievement
#15
Andrés A González-Garrido, Fabiola R Gómez-Velázquez, Ricardo A Salido-Ruiz, Aurora Espinoza-Valdez, Hugo Vélez-Pérez, Rebeca Romo-Vazquez, Geisa B Gallardo-Moreno, Vanessa D Ruiz-Stovel, Alicia Martínez-Ramos, Gustavo Berumen
Symbolic numerical magnitude processing is crucial to arithmetic development, and it is thought to be supported by the functional activation of several brain-interconnected structures. In this context, EEG beta oscillations have been recently associated with attention and working memory processing that underlie math achievement. Due to that EEG coherence represents a useful measure of brain functional connectivity, we aimed to contrast the EEG coherence in forty 8-to-9-year-old children with different math skill levels (High: HA, and Low achievement: LA) according to their arithmetic scores in the Fourth Edition of the Wide Range Achievement Test (WRAT-4) while performing a symbolic magnitude comparison task (i...
May 7, 2018: Brain and Cognition
https://www.readbyqxmd.com/read/29746013/accuracy-of-oscillatory-pressure-measured-by-mechanical-ventilators-during-high-frequency-oscillatory-ventilation-in-newborns
#16
Chiara Veneroni, Marta Tossici, Emanuela Zannin, Ilaria Milesi, Raffaele L Dellaca'
BACKGROUND: Oscillatory pressure (ΔP) measurement during high frequency oscillatory ventilation (HFOV) is technically challenging and influenced by all the components of the measurement system. OBJECTIVES: To evaluate the differences between the ΔP delivered at the inlet of the endotracheal tube and those displayed by commercial neonatal mechanical ventilators and monitoring devices and to characterize how the ventilator circuit and the flowmeter proximal to the patient affect these differences...
May 10, 2018: Pediatric Pulmonology
https://www.readbyqxmd.com/read/29743475/breaking-the-limitation-of-mode-building-time-in-an-optoelectronic-oscillator
#17
Tengfei Hao, Qizhuang Cen, Yitang Dai, Jian Tang, Wei Li, Jianping Yao, Ninghua Zhu, Ming Li
An optoelectronic oscillator (OEO) is a microwave photonic system with a positive feedback loop used to create microwave oscillation with ultra-low phase noise thanks to the employment of a high-quality-factor energy storage element, such as a fiber delay line. For many applications, a frequency-tunable microwave signal or waveform, such as a linearly chirped microwave waveform (LCMW), is also needed. Due to the long characteristic time constant required for building up stable oscillation at an oscillation mode, it is impossible to generate an LCMW with a large chirp rate using a conventional frequency-tunable OEO...
May 9, 2018: Nature Communications
https://www.readbyqxmd.com/read/29729091/systemic-low-frequency-oscillations-observed-in-the-periphery-of-healthy-human-subjects
#18
Yingwei Li, Haibing Zhang, Meiling Yu, Weiwei Yu, Blaise deB Frederick, Yunjie Tong
This study investigated the relationships of systemic low-frequency oscillations (sLFOs) measured at different peripheral sites in resting state, during passive leg raising (PLR), and during a paced breathing (PB) test. Twenty-five healthy subjects (21 to 57 years old; males: 13 and females: 12) were recruited for these experiments. During the experiments, the fluctuations of oxyhemoglobin concentration were measured at six peripheral sites (left and right toes, fingertips, and earlobes) using a multichannel near-infrared spectroscopy instrument developed by our group...
May 2018: Journal of Biomedical Optics
https://www.readbyqxmd.com/read/29726870/unconventional-strain-dependent-conductance-oscillations-in-pristine-phosphorene
#19
S J Ray, M Venkata Kamalakar
Phosphorene is a single elemental, two-dimensional semiconductor that has quickly emerged as a high mobility material for transistors and optoelectronic devices. In addition, being a 2D material it can sustain high levels of strain, enabling sensitive modification of its electronic properties. In this paper, we investigate the strain dependent electronic properties of phosphorene nanocrystals. By performing extensive calculations we determine the electrical conductance as a function of uniaxial, as well as biaxial strain stimuli and uncover a unique zone phase diagram...
May 4, 2018: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/29725072/a-megawatt-level-surface-wave-oscillator-in-y-band-with-large-oversized-structure-driven-by-annular-relativistic-electron-beam
#20
Jianguo Wang, Guangqiang Wang, Dongyang Wang, Shuang Li, Peng Zeng
High power vacuum electronic devices of millimeter wave to terahertz regime are attracting extensive interests due to their potential applications in science and technologies. In this paper, the design and experimental results of a powerful compact oversized surface wave oscillator (SWO) in Y-band are presented. The cylindrical slow wave structure (SWS) with rectangular corrugations and large diameter about 6.8 times the radiation wavelength is proposed to support the surface wave interacting with annular relativistic electron beam...
May 3, 2018: Scientific Reports
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