Read by QxMD icon Read

Phase amplitude coupling

Fan Yang, Xueqian Dong, Minjun Feng, Juan Zhao, Jianping Wang
Vibrational energy transfer in transition metal complexes with flexible structures in condensed phases is of central importance to catalytical chemistry processes. In this work, two molecules with different metal atoms, M(CO)5Br (where M = Mn, Re), were used as model systems, and their axial and radial carbonyl stretching modes as infrared probes. The central-metal effect on intramolecular vibrational energy redistribution (IVR) in M(CO)5Br was investigated in polar and nonpolar solvents. The linear infrared (IR) peak splitting between carbonyl vibrations increases as the metal atom changes from Mn to Re...
January 17, 2018: Physical Chemistry Chemical Physics: PCCP
Wuyun Shang, Fajun Xiao, Lei Han, Malin Premaratne, Ting Mei, Jianlin Zhao
We show that an azimuthally polarized beam (APB) excitation of a plasmonic Fano structure made by coupling a split-ring resonator (SRR) to a nanoarc can enhance second harmonic generation (SHG). Strikingly, an almost 30 times enhancement in SHG peak intensity can be achieved when the excitation is switched from a linearly polarized beam (LPB) to an APB. We attribute this significant enhancement of SHG to the corresponding increase in the local field intensity at the fundamental frequency of SHG, resulting from the improved conversion efficiency between the APB excitation and the plasmonic modes of the Fano structure...
January 16, 2018: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Surajit Kayal, Khokan Roy, Siva Umapathy
Ultrafast torsional dynamics plays an important role in the photoinduced excited state dynamics. Tetraphenylethylene (TPE), a model system for the molecular motor, executes interesting torsional dynamics upon photoexcitation. The photoreaction of TPE involves ultrafast internal conversion via a nearly planar intermediate state (relaxed state) that further leads to a twisted zwitterionic state. Here, we report the photoinduced structural dynamics of excited TPE during the course of photoisomerization in the condensed phase by ultrafast Raman loss (URLS) and femtosecond transient absorption (TA) spectroscopy...
January 14, 2018: Journal of Chemical Physics
Gong Zhang, Xiao-Hua Wu, Guo-Zhong Xu, Shi-Jun Weng, Xiong-Li Yang, Yong-Mei Zhong
Orexin-A, -B play a crucial role in arousal and feeding by activating two G-protein-coupled receptors: orexin receptor 1 (OX1R) and orexin receptor 2 (OX2R). Orexins, along with orexin receptors, are expressed in retinal neurons, and they have been shown to differentially modulate excitatory AMPA receptors of amacrine and ganglion cells in the inner retina. In this work we report that orexin-B modulates the activity of rod bipolar cells (RBCs) located in the outer retina of rat. Intravitreal injection of orexin-B increased the amplitude of the scotopic electroretinographic b-wave, a reflection of RBC activity, recorded in vivo...
January 8, 2018: Neuropharmacology
Osman Balci, Nurbek Kakenov, Ertugrul Karademir, Sinan Balci, Semih Cakmakyapan, Emre O Polat, Humeyra Caglayan, Ekmel Özbay, Coskun Kocabas
Metamaterials bring subwavelength resonating structures together to overcome the limitations of conventional materials. The realization of active metadevices has been an outstanding challenge that requires electrically reconfigurable components operating over a broad spectrum with a wide dynamic range. However, the existing capability of metamaterials is not sufficient to realize this goal. By integrating passive metamaterials with active graphene devices, we demonstrate a new class of electrically controlled active metadevices working in microwave frequencies...
January 2018: Science Advances
Gabriel Amador de Lara, Ivan Alekseichuk, Zsolt Turi, Albert Lehr, Andrea Antal, Walter Paulus
BACKGROUND: Phase-amplitude cross-frequency coupling (PAC) is characterized by the modulation of the power of a fast brain oscillation (e.g., gamma) by the phase of a slow rhythm (e.g., theta). PAC in different sub- and neocortical regions is known to underlie effective neural communication and correlates with successful long-term memory formation. OBJECTIVE/HYPOTHESIS: The present work aims to extend earlier observational data, by probing the functional role of theta-gamma PAC in the left temporal cortex in humans during verbal long-term memory encoding...
December 25, 2017: Brain Stimulation
Til O Bergmann, Jan Born
In this issue of Neuron, Helfrich et al. (2017) demonstrate that phase-amplitude coupling (PAC) between slow oscillations and spindles is crucial for memory consolidation, and shifts in its phase relationship may explain age-related deficits in memory performance. These results also suggest a more general function of PAC in synaptic plasticity.
January 3, 2018: Neuron
P L Read, X Morice-Atkinson, E J Allen, A A Castrejón-Pita
A series of laboratory experiments in a thermally driven, rotating fluid annulus are presented that investigate the onset and characteristics of phase synchronization and frequency entrainment between the intrinsic, chaotic, oscillatory amplitude modulation of travelling baroclinic waves and a periodic modulation of the (axisymmetric) thermal boundary conditions, subject to time-dependent coupling. The time-dependence is in the form of a prescribed duty cycle in which the periodic forcing of the boundary conditions is applied for only a fraction δ of each oscillation...
December 2017: Chaos
G Lantz, M J Neugebauer, M Kubli, M Savoini, E Abreu, K Tasca, C Dornes, V Esposito, J Rittmann, Y W Windsor, P Beaud, G Ingold, S L Johnson
The prototypical magnetic memory shape alloy Ni_{2}MnGa undergoes various phase transitions as a function of the temperature, pressure, and doping. In the low-temperature phases below 260 K, an incommensurate structural modulation occurs along the [110] direction which is thought to arise from the softening of a phonon mode. It is not at present clear how this phenomenon is related, if at all, to the magnetic memory effect. Here we report time-resolved measurements which track both the structural and magnetic components of the phase transition from the modulated cubic phase as it is brought into the high-symmetry phase...
December 1, 2017: Physical Review Letters
Yuta Murakami, Denis Golež, Martin Eckstein, Philipp Werner
We study the dynamics of excitonic insulators coupled to phonons using the time-dependent mean-field theory. Without phonon couplings, the linear response is given by the damped amplitude oscillations of the order parameter with a frequency equal to the minimum band gap. A phonon coupling to the interband transfer integral induces two types of long-lived collective oscillations of the amplitude, one originating from the phonon dynamics and the other from the phase mode, which becomes massive. We show that, even for small phonon coupling, a photoinduced enhancement of the exciton condensation and the gap can be realized...
December 15, 2017: Physical Review Letters
Yuhui Li, Chunxiu Yu, Zhe Charles Zhou, Iain Stitt, Kristin K Sellers, John H Gilmore, Flavio Frohlich
Although oscillations during development have been characterized in a wide range of neural systems, little is known about the interaction between these network oscillations and neuronal spiking, and the interactions among different oscillation frequencies. Here we recorded the spontaneous and visual-elicited local field potential (LFP) and multi-unit activity (MUA) in the visual cortex of freely-moving juvenile ferrets before and after eye-opening. We found that both the spontaneous and visually-elicited LFP power was increased after eye-opening, especially in higher frequency bands (>30 Hz)...
December 19, 2017: Scientific Reports
Shaopeng Liu, Wen-Xing Yang, Tao Shui, Zhonghu Zhu, Ai-Xi Chen
We propose an efficient scheme for the controllable amplification of two-phonon higher-order sidebands in a quadratically coupled optomechanical system. In this scheme, a strong control field and a weak probe pulse are injected into the cavity, and the membrane located at the middle position of the cavity is driven resonantly by a weak coherent mechanical pump. Beyond the conventional linearized approximation, we derive analytical expressions for the output transmission of probe pulse and the amplitude of second-order sideband by adding the nonlinear coefficients into the Heisenberg-Langevin formalism...
December 15, 2017: Scientific Reports
Philip A Kovac, Jeffrey A Cina
We report the successful application of a recently developed mixed quantum/semiclassical wave-packet dynamical theory to the calculation of a spectroscopic signal, the linear absorption spectrum of a realistic small-molecule chromophore in a cryogenic environment. This variational fixed vibrational basis/Gaussian bath (FVB/GB) theory avails itself of an assumed time scale separation between a few, mostly intramolecular, high-frequency nuclear motions and a larger number of slower degrees of freedom primarily associated with an extended host medium...
December 14, 2017: Journal of Chemical Physics
Giovanni Mento, Duncan E Astle, Gaia Scerif
Temporal orienting of attention operates by biasing the allocation of cognitive and motor resources in specific moments in time, resulting in the improved processing of information from expected compared with unexpected targets. Recent findings have shown that temporal orienting operates relatively early across development, suggesting that this attentional mechanism plays a core role for human cognition. However, the exact neurophysiological mechanisms allowing children to attune their attention over time are not well understood...
December 15, 2017: Journal of Cognitive Neuroscience
Julian Léonard, Andrea Morales, Philip Zupancic, Tobias Donner, Tilman Esslinger
Higgs and Goldstone modes are collective excitations of the amplitude and phase of an order parameter that is related to the breaking of a continuous symmetry. We directly studied these modes in a supersolid quantum gas created by coupling a Bose-Einstein condensate to two optical cavities, whose field amplitudes form the real and imaginary parts of a U(1)-symmetric order parameter. Monitoring the cavity fields in real time allowed us to observe the dynamics of the associated Higgs and Goldstone modes and revealed their amplitude and phase nature...
December 15, 2017: Science
Liron Stern, Meir Grajower, Noa Mazurski, Uriel Levy
Following the efforts of size reduction and integration of light and vapor systems, great promise is held in the integration of vapor and confined electromagnetic waves. By confining light to nanoscale dimensions, fundamental properties of light-vapor interactions may vary significantly. For example, the state of polarization may be modified as compared to weakly focused beams. Specifically, in transverse magnetic modes the existence of a longitudinal field component which is in quadrature to the transverse field, generates a "circularly-like" polarized light...
December 14, 2017: Nano Letters
Austin E Soplata, Michelle M McCarthy, Jason Sherfey, Shane Lee, Patrick L Purdon, Emery N Brown, Nancy Kopell
The anesthetic propofol elicits many different spectral properties on the EEG, including alpha oscillations (8-12 Hz), Slow Wave Oscillations (SWO, 0.1-1.5 Hz), and dose-dependent phase-amplitude coupling (PAC) between alpha and SWO. Propofol is known to increase GABAA inhibition and decrease H-current strength, but how it generates these rhythms and their interactions is still unknown. To investigate both generation of the alpha rhythm and its PAC to SWO, we simulate a Hodgkin-Huxley network model of a hyperpolarized thalamus and corticothalamic inputs...
December 11, 2017: PLoS Computational Biology
Laura Gagliano, Elie Bou Assi, Dang K Nguyen, Sandy Rihana, Mohamad Sawan
Seizure forecasting would improve the quality of life of patients with refractory epilepsy. Although early findings were optimistic, no single feature has been found capable of individually characterizing brain dynamics during transition to seizure. Cross-frequency phase amplitude coupling has been recently proposed as a precursor of seizure activity. This work evaluates the existence of a statistically significant difference in mean phase amplitude coupling distribution between the preictal and interictal states of seizures in dogs with bilaterally implanted intracranial electrodes...
November 26, 2017: Epilepsy Research
Z L Cao, H C Ong
By manipulating the relative amplitude and phase between two incoming lights, coherent control of photonic systems can be realized. Here, we show by temporal coupled mode theory and finite-difference time-domain simulation that a coupled system can be actively controlled to exhibit plenty of different spectral, angular, and excitation behaviors. Electromagnetically induced transparency-like and Fano spectral characteristics as well as strong beam steering have been observed. Remarkably, by selectively exciting the coupled modes, we have developed a new approach to determine the complex Hermitian and anti-Hermitian interaction constants...
November 27, 2017: Optics Express
Christoph Schmal, Erik D Herzog, Hanspeter Herzel
Modern imaging techniques allow the monitoring of circadian rhythms of single cells. Coupling between these single cellular circadian oscillators can generate coherent periodic signals on the tissue level that subsequently orchestrate physiological outputs. The strength of coupling in such systems of oscillators is often unclear. In particular, effects on coupling strength by varying cell densities, by knockouts, and by inhibitor applications are debated. In this study, we suggest to quantify the relative coupling strength via analyzing period, phase, and amplitude distributions in ensembles of individual circadian oscillators...
December 1, 2017: Journal of Biological Rhythms
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"