Time-reversal mirrors have been successfully implemented for various kinds of waves propagating in complex media. In particular, acoustic waves in chaotic cavities exhibit a refocalization that is extremely robust against external perturbations or the partial use of the available information. We develop a semiclassical approach in order to quantitatively describe the refocusing signal resulting from an initially localized wave packet. The time-dependent reconstructed signal grows linearly with the temporal window of injection, in agreement with the acoustic experiments, and reaches the same spatial extension of the original wave packet. We explain the crucial role played by the chaotic dynamics for the reconstruction of the signal and its stability against external perturbations.
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http://dx.doi.org/10.1103/PhysRevLett.101.240403 | DOI Listing |
Trends Immunol
January 2025
Department of Gastroenterology, Sir Run Run Shaw Hospital, Zhejiang University, Hangzhou, Zhejiang Province, 310058, China; Institution of Gastroenterology, Zhejiang University, Hangzhou, Zhejiang Province, 310058, China. Electronic address:
Mayassi and colleagues utilized spatial transcriptomics to create a comprehensive blueprint of the mouse gut, exploring its adaptability and resilience under perturbed conditions. Their work highlights the adaptive capabilities of the murine gut's regionalized structure, providing insights into how it functions in a coordinated manner and how it responds to external challenges.
View Article and Find Full Text PDFPhys Rev Lett
December 2024
Massachusetts Institute of Technology, Cambridge, Massachusetts, USA.
We introduce an approach for analyzing the responses of dynamical systems to external perturbations that combines score-based generative modeling with the generalized fluctuation-dissipation theorem. The methodology enables accurate estimation of system responses, including those with non-Gaussian statistics. We numerically validate our approach using time-series data from three different stochastic partial differential equations of increasing complexity: an Ornstein-Uhlenbeck process with spatially correlated noise, a modified stochastic Allen-Cahn equation, and the 2D Navier-Stokes equations.
View Article and Find Full Text PDFJ Sports Sci
January 2025
Department of Movement, Human and Health Sciences, University of Rome "Foro Italico", Rome, Italy.
Anticipatory postural adjustments (APAs) are responsible for a successful first step execution in handstand walking. This study evaluates gymnasts' ability to adapt their APAs and stepping parameters in response to adding/removing an external load over repeated handstand walking initiation trials. Eighteen gymnasts performed five handstand walking initiation trials without load (PRE), eight trials with an external load (LOAD) and five trials with removed load (POST).
View Article and Find Full Text PDFActa Bioeng Biomech
June 2024
1Faculty of Rehabilitation, Józef Piłsudski University of Physical Education in Warsaw, Warsaw, Poland.
: External factors can disrupt postural control, but the intricate workings of the postural control system enable an appropriate response. This study seeks to assess how external perturbations affect postural control. : Twenty women participated in study, which consisted four trials involved quiet standing and experiencing induced perturbations by being struck with a boxing bag from the back, right, and left sides, respectively.
View Article and Find Full Text PDFJ Phys Chem A
January 2025
College of Physics, Liaoning University, Shenyang 110036, China.
Based on the DCV-C system of fullerene acceptor organic solar cell active materials, the charge transfer process of D-A type molecular materials under the action of an external electric field () was explored. Within the range of electric field application, the excited state characteristics exhibit certain regular changes. Based on reducing the excitation energy, the excitation mode shows a trend of developing toward low excited states.
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