A total of 21,040 electroencephalograms obtained from 6,834 children constituting the routine patient stock of an electroencephalographic department of a pediatric clinic were checked for "frequency instability". It was possible to observe an age dependence of this characteristic and determine statistical correlations with certain clinical disease units showing different frequencies of this particular characteristic, especially neuropathies and neuroses.
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Nanoscale
September 2022
College of Precision Instruments and Opto-electronics Engineering, Tianjin University, Tianjin, 300072, China.
The phenomenon of multi-resonant Fano resonances is important for the design of biosensors and communication fields. There are very few studies reporting the multi-band Fano resonance metamaterials with more than three resonance frequencies, or the tunable optical metamaterials to control the multi-band Fano resonance characteristics. Here, we report dual control of multi-band Fano resonances with a metal-halide perovskite-integrated terahertz metasurface by lasers and an electrical field.
View Article and Find Full Text PDFSci Adv
September 2021
Chalmers University of Technology, Microtechnology, and Nanoscience, SE-41296 Gothenburg, Sweden.
Frequency instability of superconducting resonators and qubits leads to dephasing and time-varying energy loss and hinders quantum processor tune-up. Its main source is dielectric noise originating in surface oxides. Thorough noise studies are needed to develop a comprehensive understanding and mitigation strategy of these fluctuations.
View Article and Find Full Text PDFChaos
December 2019
Institut für Theoretische Physik, Technische Universität Berlin, Hardenbergstraße 36, 10623 Berlin, Germany.
We consider sparse random networks of Kuramoto phase oscillators with inertia in order to mimic and investigate the dynamics emerging in high-voltage power grids. The corresponding natural frequencies are assumed to be bimodally Gaussian distributed, thus modeling the distribution of both power generators and consumers, which must be in balance. Our main focus is on the theoretical analysis of the linear stability of the frequency-synchronized state, which is necessary for the stable operation of power grids and the control of unstable synchronous states.
View Article and Find Full Text PDFSleep Med
July 2008
Division for Research and Education in Complementary and Integrative Medical Therapies, Harvard Medical School, Boston, MA 02215, USA.
Objective: To assess the effects of a 12-week Tai Chi exercise program on sleep using the sleep spectrogram, a method based on a single channel electrocardiogram (ECG)-derived estimation of cardiopulmonary coupling, previously shown to identify stable and unstable sleep states.
Methods: We retrospectively analyzed 24-h continuous ECG data obtained in a clinical trial of Tai Chi exercise in patients with heart failure. Eighteen patients with chronic stable heart failure, left ventricular ejection fraction
Taking up to fourth-order dispersion effects into account, we show that fiber resonators become stable for a large intensity regime. The range of pump intensities leading to modulational instability becomes finite and controllable. Moreover, by computing analytically the thresholds and frequencies of these instabilities, we demonstrate the existence of a new unstable frequency at the primary threshold.
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