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Phase amplitude coupling

Julia C Quindlen-Hotek, Victor H Barocas
The Pacinian corpuscle (PC) is the cutaneous mechanoreceptor responsible for sensation of high-frequency (20-1000 Hz) vibrations. PCs lie deep within the skin, often in multicorpuscle clusters with overlapping receptive fields. We developed a finite-element mechanical model of one or two PCs embedded within human skin, coupled to a multiphysics PC model to simulate action potentials elicited by each PC. A vibration was applied to the skin surface, and the resulting mechanical signal was analyzed using two metrics: the deformation amplitude ratio ([Formula: see text], [Formula: see text] and the phase shift of the vibration ([Formula: see text], [Formula: see text] between the stimulus and the PC...
March 17, 2018: Biomechanics and Modeling in Mechanobiology
T R Hartke, Y-Y Liu, M J Gullans, J R Petta
Quantum confinement leads to the formation of discrete electronic states in quantum dots. Here we probe electron-phonon interactions in a suspended InAs nanowire double quantum dot (DQD) that is electric-dipole coupled to a microwave cavity. We apply a finite bias across the wire to drive a steady state population in the DQD excited state, enabling a direct measurement of the electron-phonon coupling strength at the DQD transition energy. The amplitude and phase response of the cavity field exhibit oscillations that are periodic in the DQD energy level detuning due to the phonon modes of the nanowire...
March 2, 2018: Physical Review Letters
Aline Vochezer, Tobias Kampschulte, Klemens Hammerer, Philipp Treutlein
We observe effects of collective atomic motion in a one-dimensional optical lattice coupled to an optomechanical system. In this hybrid atom-optomechanical system, the lattice light generates a coupling between the lattice atoms as well as between atoms and a micromechanical membrane oscillator. For large atom numbers we observe an instability in the coupled system, resulting in large-amplitude atom-membrane oscillations. We show that this behavior can be explained by light-mediated collective atomic motion in the lattice, which arises for large atom numbers, small atom-light detunings, and asymmetric pumping of the lattice, in agreement with previous theoretical work...
February 16, 2018: Physical Review Letters
Xiaotian Zhang, Jiteng Sheng, Haibin Wu
We explore theoretically the optomechanical interaction between a light field and a mechanical mode mediated by a Kerr nonlinear medium inside a Fabry-Perot cavity. When the system is driven by a strong and fast amplitude-modulated light field, i.e., in the so-called temporal rocking region, the cavity field and the mechanical oscillator show the characteristics of multistability. The rocking breaks down the continuous phase symmetry of the cavity field to a bistable case of two equivalent states with exact π phase difference...
March 5, 2018: Optics Express
Ravi V Chacko, Byungchan Kim, Suh Woo Jung, Amy L Daitch, Jarod L Roland, Nicholas V Metcalf, Maurizio Corbetta, Gordon L Shulman, Eric C Leuthardt
Spatial attention is the cognitive function that coordinates the selection of visual stimuli with appropriate behavioral responses. Recent studies have reported that phase-amplitude coupling (PAC) of low and high frequencies covaries with spatial attention, but differ on the direction of covariation and the frequency ranges involved. We hypothesized that distinct phase-amplitude frequency pairs have differentiable contributions during tasks that manipulate spatial attention. We investigated this hypothesis with electrocorticography (ECoG) recordings from participants who engaged in a cued spatial attention task...
March 5, 2018: NeuroImage
David M Harcombe, Michael G Ruppert, Michael R P Ragazzon, Andrew J Fleming
An important issue in the emerging field of multifrequency atomic force microscopy (MF-AFM) is the accurate and fast demodulation of the cantilever-tip deflection signal. As this signal consists of multiple frequency components and noise processes, a lock-in amplifier is typically employed for its narrowband response. However, this demodulator suffers inherent bandwidth limitations as high-frequency mixing products must be filtered out and several must be operated in parallel. Many MF-AFM methods require amplitude and phase demodulation at multiple frequencies of interest, enabling both z -axis feedback and phase contrast imaging to be achieved...
2018: Beilstein Journal of Nanotechnology
Omel Mendoza-Yero, Miguel Carbonell-Leal, Gladys Mínguez-Vega, Jesús Lancis
We experimentally demonstrate Fresnel holograms able to produce multifocal irradiance patterns with micrometric spatial resolution. These holograms are assessed from the coherent sum of multiple Fresnel lenses. The utilized encoded technique guarantees full control over the reconstructed irradiance patterns due to an optimal codification of the amplitude and phase information of the resulting complex field. From a practical point of view, a phase-only spatial light modulator is used in a couple of experiments addressed to obtain two- and three-dimensional distributions of focal points to excite both linear and non-linear optical phenomena...
March 1, 2018: Optics Letters
Soheila Samiee, Maxime Lévesque, Massimo Avoli, Sylvain Baillet
Polyrhythmic coupling of oscillatory components in electrophysiological signals results from the interactions between neuronal sub-populations within and between cell assemblies. Since the mechanisms underlying epileptic disorders should affect such interactions, abnormal level of cross-frequency coupling is expected to provide a signal marker of epileptogenesis. We measured phase-amplitude coupling (PAC), a form of cross-frequency coupling between neural oscillations, in a rodent model of mesial temporal lobe epilepsy...
February 24, 2018: Neurobiology of Disease
Christopher K Kovach, Hiroyuki Oya, Hiroto Kawasaki
Most biological signals are non-Gaussian, reflecting their origins in highly nonlinear physiological systems. A versatile set of techniques for studying non-Gaussian signals relies on the spectral representations of higher moments, known as polyspectra, which describe forms of cross-frequency dependence that do not arise in time-invariant Gaussian signals. The most commonly used of these employ the bispectrum. Recently, other measures of cross-frequency dependence have drawn interest in EEG literature, in particular those which address phase-amplitude coupling (PAC)...
February 23, 2018: NeuroImage
J Matias Palva, Sheng H Wang, Satu Palva, Alexander Zhigalov, Simo Monto, Matthew J Brookes, Jan-Mathijs Schoffelen, Karim Jerbi
When combined with source modeling, magneto- (MEG) and electroencephalography (EEG) can be used to study long-range interactions among cortical processes non-invasively. Estimation of such inter-areal connectivity is nevertheless hindered by instantaneous field spread and volume conduction, which artificially introduce linear correlations and impair source separability in cortical current estimates. To overcome the inflating effects of linear source mixing inherent to standard interaction measures, alternative phase- and amplitude-correlation based connectivity measures, such as imaginary coherence and orthogonalized amplitude correlation have been proposed...
February 22, 2018: NeuroImage
Yuta Goto, Atsushi Okamoto, Atsushi Shibukawa, Kazuhisa Ogawa, Akihisa Tomita
We propose a virtual phase conjugation (VPC) based optical tomography (VPC-OT) for realizing single-shot optical tomographic imaging systems. Using a computer-based numerical beam propagation, the VPC combines pre-modulation and post-demodulation of the probe beam's wavefront, which provides an optical sectioning capability for resolving the depth coordinates. In VPC-OT, the physical optical microscope system and VPC are coupled using digital holography. Therefore, in contrast to conventional optical tomographic imaging (OTI) systems, this method does not require additional elements such as low-coherence light sources or confocal pinholes...
February 19, 2018: Optics Express
Aviv Karnieli, Ady Arie
We propose and analyze a new way for obtaining an adiabatic geometric phase for light, via the sum-frequency-generation nonlinear process. The state of light is represented by the complex amplitudes at two different optical frequencies, coupled by the second order nonlinearity of the medium. The dynamics of this system is then shown to be equivalent to that of a spin-1/2 particle in a magnetic field, which in turn can be rotated adiabatically on the Bloch sphere. When the input wave itself is an eigenstate of the magnetic field equivalent, the geometric phase is manifested as a pure phase factor...
February 19, 2018: Optics Express
Nianqiang Li, H Susanto, B R Cemlyn, I D Henning, M J Adams
We study the nonlinear dynamics of solitary and optically injected two-element laser arrays with a range of waveguide structures. The analysis is performed with a detailed direct numerical simulation, where high-resolution dynamic maps are generated to identify regions of dynamic instability in the parameter space of interest. Our combined one- and two-parameter bifurcation analysis uncovers globally diverse dynamical regimes (steady-state, oscillation, and chaos) in the solitary laser arrays, which are greatly influenced by static design waveguiding structures, the amplitude-phase coupling factor of the electric field, i...
February 19, 2018: Optics Express
Elinor Tzvi, Leon J Bauhaus, Till U Kessler, Matthias Liebrand, Malte Wöstmann, Ulrike M Krämer
Cross-frequency coupling is suggested to serve transfer of information between wide-spread neuronal assemblies and has been shown to underlie many cognitive functions including learning and memory. In previous work, we found that alpha (8 - 13 Hz) - gamma (30 - 48 Hz) phase amplitude coupling (αγPAC) is decreased during sequence learning in bilateral frontal cortex and right parietal cortex. We interpreted this to reflect decreased demands for visuo-motor mapping once the sequence has been encoded. In the present study, we put this hypothesis to the test by adding a "simple" condition to the standard serial reaction time task (SRTT) with minimal needs for visuo-motor mapping...
February 20, 2018: Neurobiology of Learning and Memory
Aina Luque-García, Vicent Teruel-Martí, Sergio Martínez-Bellver, Albert Adell, Ana Cervera-Ferri, Joana Martínez-Ricós
The stress system coordinates the adaptive reactions of the organism to stressors. So, dysfunctions in this circuit may correlate to anxiety-related disorders, including depression. Comprehending the dynamics of this network may lead to a better understanding of the mechanisms that underlie these diseases. The central nucleus of the amygdala (CeA) activates the hypothalamic-pituitary-adrenal axis and brainstem nodes by triggering endocrine, autonomic and behavioural stress responses. The medial prefrontal cortex plays a significant role in regulating reactions to stressors, and is specifically important for limiting fear responses...
February 23, 2018: Journal of Comparative Neurology
Ioannis Smyrnias, Normann Goodwin, Dagmar Wachten, Jonas Skogestad, Jan Magnus Aronsen, Emma L Robinson, Kateryna Demydenko, Anne Segonds-Pichon, David Oxley, Sakthivel Sadayappan, Karin Sipido, Martin D Bootman, H Llewelyn Roderick
The shortening of sarcomeres that co-ordinates the pump function of the heart is stimulated by electrically-mediated increases in [Ca2+ ]. This process of excitation-contraction coupling (ECC) is subject to modulation by neurohormonal mediators that tune the output of the heart to meet the needs of the organism. Endothelin-1 (ET-1) is a potent modulator of cardiac function with effects on contraction amplitude, chronotropy and automaticity. The actions of ET-1 are evident during normal adaptive physiological responses and increased under pathophysiological conditions, such as following myocardial infarction and during heart failure, where ET-1 levels are elevated...
February 19, 2018: Journal of Molecular and Cellular Cardiology
Yan Li, Shu-Xiao Li, Fei Gao, Hai-Ou Li, Gang Xu, Ke Wang, Di Liu, Gang Cao, Ming Xiao, Ting Wang, Jianjun Zhang, Guang-Can Guo, Guo-Ping Guo
Realizing a strong coupling between spin and resonator is an important issue for scalable quantum computation in semiconductor systems. Benefiting from the advantages of strong spin-orbit coupling strength and long coherence time, the Ge hut wire, which is proposed to be site-controlled grown for scalability, is considered as a promising candidate to achieve this goal. Here we present a hybrid architecture in which an on-chip superconducting microwave resonator is coupled to the holes in a Ge quantum dot. The charge stability diagram can be obtained from the amplitude and phase response of the resonator independently from the DC transport measurement...
February 22, 2018: Nano Letters
Philip Willke, William Paul, Fabian D Natterer, Kai Yang, Yujeong Bae, Taeyoung Choi, Joaquin Fernández-Rossier, Andreas J Heinrich, Christoper P Lutz
Spin resonance of individual spin centers allows applications ranging from quantum information technology to atomic-scale magnetometry. To protect the quantum properties of a spin, control over its local environment, including energy relaxation and decoherence processes, is crucial. However, in most existing architectures, the environment remains fixed by the crystal structure and electrical contacts. Recently, spin-polarized scanning tunneling microscopy (STM), in combination with electron spin resonance (ESR), allowed the study of single adatoms and inter-atomic coupling with an unprecedented combination of spatial and energy resolution...
February 2018: Science Advances
Massimo Vergassola, Victoria E Deneke, Stefano Di Talia
Early embryogenesis of most metazoans is characterized by rapid and synchronous cleavage divisions. Chemical waves of Cdk1 activity were previously shown to spread across Drosophila embryos, and the underlying molecular processes were dissected. Here, we present the theory of the physical mechanisms that control Cdk1 waves in Drosophila The in vivo dynamics of Cdk1 are captured by a transiently bistable reaction-diffusion model, where time-dependent reaction terms account for the growing level of cyclins and Cdk1 activation across the cell cycle...
February 15, 2018: Proceedings of the National Academy of Sciences of the United States of America
Romesh G Abeysuriya, Steven W Lockley, Peter A Robinson, Svetlana Postnova
A biophysical model of the key aspects of melatonin synthesis and excretion has been developed, which is able to predict experimental dynamics of melatonin in plasma and saliva, and of its urinary metabolite 6-sulfatoxymelatonin (aMT6s). This new model is coupled to an established model of arousal dynamics, which predicts sleep and circadian dynamics based on light exposure and times of wakefulness. The combined model thus predicts melatonin levels over the sleep-wake/dark-light cycle and enables prediction of melatonin-based circadian phase markers, such as dim light melatonin onset (DLMO) and aMT6s acrophase under conditions of normal sleep and circadian misalignment...
February 13, 2018: Journal of Pineal Research
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