Mesoscopic oscillatory reaction systems, for example in cell biology, can exhibit stochastic oscillations in the form of cyclic random walks even if the corresponding macroscopic system does not oscillate. We study how the intrinsic noise from molecular discreteness influences the frequency spectrum of mesoscopic oscillators using as a model system a cascade of coupled Brusselators away from the Hopf bifurcation. The results show that the spectrum of an oscillator depends on the level of noise. In particular, the peak frequency of the oscillator is reduced by increasing noise, and the bandwidth increased. Along a cascade of coupled oscillators, the peak frequency is further reduced with every stage and also the bandwidth is reduced. These effects can help understand the role of noise in chemical oscillators and provide fingerprints for more reliable parameter identification and volume measurement from experimental spectra.
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http://dx.doi.org/10.1038/srep00154 | DOI Listing |
Micromachines (Basel)
January 2025
Key Laboratory of Instrumentation Science and Dynamic Measurement Ministry of Education, North University of China, Taiyuan 030051, China.
A Hz level narrow linewidth all-optical microwave oscillator based on the torsional radial acoustic modes (TR) of a single-mode fiber (SMF) is proposed and validated. The all-optical microwave oscillator consists of a 20 km SMF main ring cavity and a 5 km SMF sub ring cavity. The main ring cavity provides forward stimulated Brillouin scattering gain and utilizes a nonlinear polarization rotation effect to achieve TR mode locking.
View Article and Find Full Text PDFJ Pers Med
December 2024
Department of Medicine, Hadassah Medical Center, Faculty of Medicine, Hebrew University, Jerusalem 9112102, Israel.
Different disciplines are developing various methods for determining and dealing with uncertainties in complex systems. The constrained disorder principle (CDP) accounts for the randomness, variability, and uncertainty that characterize biological systems and are essential for their proper function. Per the CDP, intrinsic unpredictability is mandatory for the dynamicity of biological systems under continuously changing internal and external perturbations.
View Article and Find Full Text PDFVision (Basel)
January 2025
Centre Gilles Gaston Granger, UMR 7304 Centre National de la Recherche Scientifique, Aix Marseille Université, 13621 Aix-en-Provence, France.
The appearance of an object triggers an orienting gaze movement toward its location. The movement consists of a rapid rotation of the eyes, the saccade, which is accompanied by a head rotation if the target eccentricity exceeds the oculomotor range and by a slow eye movement if the target moves. Completing a previous report, we explain the numerous points that lead to questioning the validity of a one-to-one correspondence relation between measured physical values of gaze or head orientation and neuronal activity.
View Article and Find Full Text PDFNature
January 2025
Institute of Physics, Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland.
The integrated frequency comb generator based on Kerr parametric oscillation has led to chip-scale, gigahertz-spaced combs with new applications spanning hyperscale telecommunications, low-noise microwave synthesis, light detection and ranging, and astrophysical spectrometer calibration. Recent progress in lithium niobate (LiNbO) photonic integrated circuits (PICs) has resulted in chip-scale, electro-optic (EO) frequency combs, offering precise comb-line positioning and simple operation without relying on the formation of dissipative Kerr solitons. However, current integrated EO combs face limited spectral coverage due to the large microwave power required to drive the non-resonant capacitive electrodes and the strong intrinsic birefringence of LiNbO.
View Article and Find Full Text PDFJ Neurosci
January 2025
Department of Mathematics, Polytechnic University of Catalonia, Spain.
The brain's activity fluctuations have different temporal scales across the brain regions, with associative regions displaying slower timescales than sensory areas. This so-called hierarchy of timescales has been shown to correlate with both structural brain connectivity and intrinsic regional properties. Here, using publicly available human resting-state fMRI and dMRI data it was found that, while more structurally connected brain regions presented activity fluctuations with longer timescales, their activity fluctuations presented lower variance.
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