keyword
https://read.qxmd.com/read/38465256/physics-constrained-data-driven-variational-method-for-discrepancy-modeling
#21
JOURNAL ARTICLE
Arif Masud, Sharbel Nashar, Shoaib Goraya
This paper presents a data-driven discrepancy modeling method that variationally embeds measured data in the modeling and analysis framework. The proposed method exploits the residual between the first-principles theory and sensor-based measurements from the dynamical system, and it augments the physics-based model with a variationally derived loss function that is comprised of this residual. The method was first developed in the context of linear elasticity (Masud and Goraya, J. Appl. Mech. 89 (11), 111001 (2022)) wherein the relation between the discrepancy model and loss terms was derived to show that the data embedding terms behave like residual-based least-squares regression functions...
December 15, 2023: Computer Methods in Applied Mechanics and Engineering
https://read.qxmd.com/read/38461414/granular-retrosplenial-cortex-layer-2-3-generates-high-frequency-oscillations-dynamically-coupled-with-hippocampal-rhythms-across-brain-states
#22
JOURNAL ARTICLE
Kaiser C Arndt, Earl T Gilbert, Lianne M F Klaver, Jongwoon Kim, Chelsea M Buhler, Julia C Basso, Sam McKenzie, Daniel Fine English
The granular retrosplenial cortex (gRSC) exhibits high-frequency oscillations (HFOs; ∼150 Hz), which can be driven by a hippocampus-subiculum pathway. How the cellular-synaptic and laminar organization of gRSC facilitates HFOs is unknown. Here, we probe gRSC HFO generation and coupling with hippocampal rhythms using focal optogenetics and silicon-probe recordings in behaving mice. ChR2-mediated excitation of CaMKII-expressing cells in L2/3 or L5 induces HFOs, but spontaneous HFOs are found only in L2/3, where HFO power is highest...
March 8, 2024: Cell Reports
https://read.qxmd.com/read/38458483/fundamentals-of-sleep-regulation-model-and-benchmark-values-for-fractal-and-oscillatory-neurodynamics
#23
JOURNAL ARTICLE
Róbert Bódizs, Bence Schneider, Péter P Ujma, Csenge G Horváth, Martin Dresler, Yevgenia Rosenblum
Homeostatic, circadian and ultradian mechanisms play crucial roles in the regulation of sleep. Evidence suggests that ratios of low-to-high frequency power in the electroencephalogram (EEG) spectrum indicate the instantaneous level of sleep pressure, influenced by factors such as individual sleep-wake history, current sleep stage, age-related differences and brain topography characteristics. These effects are well captured and reflected in the spectral exponent, a composite measure of the constant low-to-high frequency ratio in the periodogram, which is scale-free and exhibits lower interindividual variability compared to slow wave activity, potentially serving as a suitable standardization and reference measure...
March 6, 2024: Progress in Neurobiology
https://read.qxmd.com/read/38457022/viscoelasticity-of-a-carbon-nanotube-laden-air-water-interface
#24
JOURNAL ARTICLE
Shing-Yun Chang, Sahil R Vora, Charles D Young, Abhishek Shetty, Anson W K Ma
The viscoelasticity of a carbon nanotube (CNT)-laden air-water interface was characterized using two different experimental methods. The first experimental method used a Langmuir-Pockels (LP) trough coupled with a pair of oscillating barriers. The second method is termed the Bicone-Trough (BT) method, where a LP trough was custom-built and fit onto a rheometer equipped with a bicone fixture to standardize the preparation and conditioning of a particle-laden interface especially at high particle coverages. The performance of both methods was evaluated by performing Fast Fourier Transform (FFT) analysis to calculate the signal-to-noise ratios (SNR)...
March 8, 2024: European Physical Journal. E, Soft Matter
https://read.qxmd.com/read/38453917/transient-stimulated-raman-scattering-spectroscopy-and-imaging
#25
JOURNAL ARTICLE
Qiaozhi Yu, Zhengjian Yao, Jiaqi Zhou, Wenhao Yu, Chenjie Zhuang, Yafeng Qi, Hanqing Xiong
Stimulated Raman scattering (SRS) has been developed as an essential quantitative contrast for chemical imaging in recent years. However, while spectral lines near the natural linewidth limit can be routinely achieved by state-of-the-art spontaneous Raman microscopes, spectral broadening is inevitable for current mainstream SRS imaging methods. This is because those SRS signals are all measured in the frequency domain. There is a compromise between sensitivity and spectral resolution: as the nonlinear process benefits from pulsed excitations, the fundamental time-energy uncertainty limits the spectral resolution...
March 8, 2024: Light, Science & Applications
https://read.qxmd.com/read/38453900/walking-modulates-visual-detection-performance-according-to-stride%C3%A2-cycle-phase
#26
JOURNAL ARTICLE
Matthew J Davidson, Frans A J Verstraten, David Alais
Walking is among our most frequent and natural of voluntary behaviours, yet the consequences of locomotion upon perceptual and cognitive function remain largely unknown. Recent work has highlighted that although walking feels smooth and continuous, critical phases exist within each step for the successful coordination of perceptual and motor function. Here, we test whether these phasic demands impact upon visual perception, by assessing performance in a visual detection task during natural unencumbered walking...
March 7, 2024: Nature Communications
https://read.qxmd.com/read/38453897/disentangling-top-down-drivers-of-mortality-underlying-diel-population-dynamics-of-prochlorococcus-in-the-north-pacific-subtropical-gyre
#27
JOURNAL ARTICLE
Stephen J Beckett, David Demory, Ashley R Coenen, John R Casey, Mathilde Dugenne, Christopher L Follett, Paige Connell, Michael C G Carlson, Sarah K Hu, Samuel T Wilson, Daniel Muratore, Rogelio A Rodriguez-Gonzalez, Shengyun Peng, Kevin W Becker, Daniel R Mende, E Virginia Armbrust, David A Caron, Debbie Lindell, Angelicque E White, François Ribalet, Joshua S Weitz
Photosynthesis fuels primary production at the base of marine food webs. Yet, in many surface ocean ecosystems, diel-driven primary production is tightly coupled to daily loss. This tight coupling raises the question: which top-down drivers predominate in maintaining persistently stable picocyanobacterial populations over longer time scales? Motivated by high-frequency surface water measurements taken in the North Pacific Subtropical Gyre (NPSG), we developed multitrophic models to investigate bottom-up and top-down mechanisms underlying the balanced control of Prochlorococcus populations...
March 7, 2024: Nature Communications
https://read.qxmd.com/read/38451777/isotachophoresis-with-oscillating-sample-zones-to-control-the-spatial-overlap-of-co-focused-species
#28
JOURNAL ARTICLE
Florian Gebhard, Henning Bonart, Tamal Roy, Tobias Meckel, Steffen Hardt
Microfluidic isotachophoresis (ITP) is a powerful technique that can significantly increase the reaction rate of homogeneous chemical reactions by cofocusing reactants in a narrow sample zone. Correspondingly, ITP has been utilized to reduce the reaction time in various bioanalytical assays. However, in conventional ITP, it is hardly possible to control the reaction rate in real time, i.e., speeding up or slowing down a reaction on demand. Here, we experimentally demonstrate a new mode of ITP that allows the spatial overlap of two ITP zones to be precisely controlled over time, which is a crucial first step toward controlling reaction rates...
March 7, 2024: Analytical Chemistry
https://read.qxmd.com/read/38449783/neural-network-based-estimation-of-biomechanical-vocal-fold-parameters
#29
JOURNAL ARTICLE
Jonas Donhauser, Bogac Tur, Michael Döllinger
Vocal fold (VF) vibrations are the primary source of human phonation. High-speed video (HSV) endoscopy enables the computation of descriptive VF parameters for assessment of physiological properties of laryngeal dynamics, i.e., the vibration of the VFs. However, underlying biomechanical factors responsible for physiological and disordered VF vibrations cannot be accessed. In contrast, physically based numerical VF models reveal insights into the organ's oscillations, which remain inaccessible through endoscopy...
2024: Frontiers in Physiology
https://read.qxmd.com/read/38448697/integrated-frequency-modulated-optical-parametric-oscillator
#30
JOURNAL ARTICLE
Hubert S Stokowski, Devin J Dean, Alexander Y Hwang, Taewon Park, Oguz Tolga Celik, Timothy P McKenna, Marc Jankowski, Carsten Langrock, Vahid Ansari, Martin M Fejer, Amir H Safavi-Naeini
Optical frequency combs have revolutionized precision measurement, time-keeping and molecular spectroscopy1-7 . A substantial effort has developed around 'microcombs': integrating comb-generating technologies into compact photonic platforms5,7-9 . Current approaches for generating these microcombs involve either the electro-optic10 or Kerr mechanisms11 . Despite rapid progress, maintaining high efficiency and wide bandwidth remains challenging. Here we introduce a previously unknown class of microcomb-an integrated device that combines electro-optics and parametric amplification to yield a frequency-modulated optical parametric oscillator (FM-OPO)...
March 2024: Nature
https://read.qxmd.com/read/38448607/validation-of-numerical-simulations-and-experiments-on-impulse-characteristics-induced-by-self-excited-oscillation
#31
JOURNAL ARTICLE
Qiang Wu, Guodong Ji, Jian Zhao, Liudang Sun, Dapeng Han, Li Liu, Huaigang Hu, Jinping Yu, Changchang Chen, Yuqi Sun, Jinyong Guo
The high-frequency pulse flow, equivalent to the natural frequency of rocks, is generated by a self-excited oscillating cavity to achieve resonance rock-breaking. The flow field and oscillating mechanism of the self-excited oscillating cavity were simulated using the large eddy simulation method of Computational Fluid Dynamics (CFD). A field-scale testing apparatus was developed to investigate the impulse characteristics and verify the simulation results. The results show that the fluid at the outlet at the tool is deflected due to the pulse oscillation of the fluid...
March 6, 2024: Scientific Reports
https://read.qxmd.com/read/38448599/photonic-chip-based-low-noise-microwave-oscillator
#32
JOURNAL ARTICLE
Igor Kudelin, William Groman, Qing-Xin Ji, Joel Guo, Megan L Kelleher, Dahyeon Lee, Takuma Nakamura, Charles A McLemore, Pedram Shirmohammadi, Samin Hanifi, Haotian Cheng, Naijun Jin, Lue Wu, Samuel Halladay, Yizhi Luo, Zhaowei Dai, Warren Jin, Junwu Bai, Yifan Liu, Wei Zhang, Chao Xiang, Lin Chang, Vladimir Iltchenko, Owen Miller, Andrey Matsko, Steven M Bowers, Peter T Rakich, Joe C Campbell, John E Bowers, Kerry J Vahala, Franklyn Quinlan, Scott A Diddams
Numerous modern technologies are reliant on the low-phase noise and exquisite timing stability of microwave signals. Substantial progress has been made in the field of microwave photonics, whereby low-noise microwave signals are generated by the down-conversion of ultrastable optical references using a frequency comb1-3 . Such systems, however, are constructed with bulk or fibre optics and are difficult to further reduce in size and power consumption. In this work we address this challenge by leveraging advances in integrated photonics to demonstrate low-noise microwave generation via two-point optical frequency division4,5 ...
March 6, 2024: Nature
https://read.qxmd.com/read/38446362/tilt-evoked-breathing-driven-blood-pressure-oscillations-independence-from-baroreflex-sympathoneural-function
#33
JOURNAL ARTICLE
Edward Grabov, Patti Sullivan, Siqi Wang, David S Goldstein
PURPOSE: Orthostasis increases the variability of continuously recorded blood pressure (BP). Low-frequency (LF) BP oscillations (Mayer waves) in this setting are related to the vascular-sympathetic baroreflex. Mechanisms of increased high-frequency (HF) BP oscillations at the periodicity of respiration during orthostasis have received less research attention. A previously reported patient with post-neurosurgical orthostatic hypotension (OH) and vascular-sympathetic baroreflex failure had large tilt-evoked, breathing-driven BP oscillations, suggesting that such oscillations can occur independently of vascular-sympathetic baroreflex modulation...
March 6, 2024: Clinical Autonomic Research: Official Journal of the Clinical Autonomic Research Society
https://read.qxmd.com/read/38439470/high-resolution-and-large-measurement-range-voltage-sensing-based-on-an-optoelectronic-oscillator-utilizing-an-unbalanced-mach-zehnder-interferometer
#34
JOURNAL ARTICLE
Beilei Wu, Hong Chen, Muguang Wang, Bin Yin, Jiuyang Ma, Xiaotong Zhao, Shiying Xiao, Shiyi Cai, Fengping Yan
A voltage sensor with high resolution and large measurement range based on an optoelectronic oscillator (OEO) is proposed and experimentally demonstrated. The key component in the cavity to select the oscillating signal is a finite impulse response (FIR)-microwave photonic filter (MPF) which consists of a sinusoidal broadband optical signal, an unbalanced Mach-Zehnder interferometer (MZI), a section of dispersion compensating fiber, and a photodetector. The center frequency of the FIR-MPF is mainly determined by the free spectral range (FSR) of the FIR-MPF...
February 26, 2024: Optics Express
https://read.qxmd.com/read/38439235/tunable-single-frequency-hz-magnitude-narrow-linewidth-brillouin-fiber-laser-based-on-parity-time-symmetry
#35
JOURNAL ARTICLE
Yanzhi Lv, Bin Yin, Xiangcheng Chen, Guofeng Sang, Shilin Liu, Guangbo Li, Shiying Xiao, Muguang Wang, Songhua Wu
An Hz-magnitude ultra-narrow linewidth single-frequency Brillouin fiber laser (BFL) is proposed and experimentally demonstrated. The single frequency of the laser is selected by parity-time (PT) symmetry, which consists of a stimulated Brillouin scatter (SBS) gain path excited by a 24 km single-mode fiber (SMF) and an approximately equal length loss path tuned with a variable optical attenuator (VOA). These paths are coupled through a fiber Bragg grating (FBG) into a wavelength space. Accomplishing single-frequency oscillation involves the precise adjustment of polarization control (PC) and VOA to attain the PT broken phase...
February 12, 2024: Optics Express
https://read.qxmd.com/read/38439224/high-resolution-acoustic-sensing-based-on-microcavity-optomechanical-oscillator
#36
JOURNAL ARTICLE
Rong Wang, WenYao Liu, Ziwen Pan, WenJie Fan, Lai Liu, Enbo Xing, Yanru Zhou, Jun Tang, Jun Liu
In this paper, a simple sensing method based on a silicon oxide microcavity optomechanical oscillator (OMO) is proposed and demonstrated for the detection of acoustic signals. Firstly, the resonance damping was reduced by improving the optical quality factor (Qo ) and increasing the sphere-to-neck ratio. After optimizing the process, a microsphere OMO was fabricated, which has an ultra-high mechanical quality factor (6.8 × 106 ) and greater sphere-to-neck ratio (∼11:1), based on which ultra-narrow linewidth phonon laser (∼1 Hz) is constructed...
February 12, 2024: Optics Express
https://read.qxmd.com/read/38437304/multiline-molecular-tagging-velocimetry-of-nitric-oxide-at-100%C3%A2-%C3%A2-khz-using-an-injection-seeded-burst-mode-opo
#37
JOURNAL ARTICLE
Neil S Rodrigues, Naibo Jiang, Paul Hsu, Sukesh Roy, Paul M Danehy
An injection-seeded, burst-mode optical parametric oscillator (OPO) operating at a repetition rate of 100 kHz is used to demonstrate the multiline molecular tagging velocimetry of an underexpanded jet using nitric oxide fluorescence. The very narrow linewidth of the OPO system, along with the relatively high pulse energies of the burst-mode system, enables efficient single-photon excitation of nitric oxide along multiple laser beam lines at a high repetition rate. Simultaneous one-dimensional velocity profile measurements were obtained of an underexpanded jet system at six different locations using a reference initial image and single-shot delayed images...
February 10, 2024: Applied Optics
https://read.qxmd.com/read/38424592/resting-state-cortical-electroencephalogram-rhythms-and-network-in-patients-after-chronic-stroke
#38
JOURNAL ARTICLE
Jack Jiaqi Zhang, Zhongfei Bai, Kenneth N K Fong
OBJECTIVE: To investigate the resting-state cortical electroencephalogram (EEG) rhythms and networks in patients with chronic stroke and examine their correlation with motor functions of the hemiplegic upper limb. METHODS: Resting-state EEG data from 22 chronic stroke patients were compared to EEG data from 19 age-matched and 16 younger-age healthy controls. The EEG rhythmic powers and network metrics were analyzed. Upper limb motor functions were evaluated using the Fugl-Meyer assessment-upper extremity scores and action research arm test...
February 29, 2024: Journal of Neuroengineering and Rehabilitation
https://read.qxmd.com/read/38420682/benefits-of-intratracheal-and-extrathoracic-high-frequency-percussive-ventilation-in-a-model-of-capnoperitoneum
#39
JOURNAL ARTICLE
Ferenc Peták, Roberta Südy, John Diaper, Fabienne Fontao, Davide Bizzotto, Raffaele L Dellacà, Walid Habre, Álmos Schranc
Abdominal inflation with CO2 is used to facilitate laparoscopic surgeries, however providing adequate mechanical ventilation in this scenario is of major importance during anesthesia management. We characterized high frequency percussive ventilation (HFPV) in protecting from the gas exchange and respiratory mechanical impairments during capnoperitoneum. In addition, we aimed to assess the difference between conventional pressure-controlled mechanical ventilation (CMV) and HFPV modalities generating the high-frequency signal intratracheally (HFPVi) or extrathoracally (HFPVe)...
February 29, 2024: Journal of Applied Physiology
https://read.qxmd.com/read/38419723/three-dimensional-array-of-microbubbles-sonoporation-of-cells-in-microfluidics
#40
JOURNAL ARTICLE
Guangyong Huang, Lin Lin, Quanhui Liu, Shixiong Wu, Jiapeng Chen, Rongxing Zhu, Hui You, Cuimin Sun
Sonoporation is a popular membrane disruption technique widely applicable in various fields, including cell therapy, drug delivery, and biomanufacturing. In recent years, there has been significant progress in achieving controlled, high-viability, and high-efficiency cell sonoporation in microfluidics. If the microchannels are too small, especially when scaled down to the cellular level, it still remains a challenge to overcome microchannel clogging, and low throughput. Here, we presented a microfluidic device capable of modulating membrane permeability through oscillating three-dimensional array of microbubbles...
2024: Frontiers in Bioengineering and Biotechnology
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