@article{12791, abstract = {We investigate the capabilities of Physics-Informed Neural Networks (PINNs) to reconstruct turbulent Rayleigh–Bénard flows using only temperature information. We perform a quantitative analysis of the quality of the reconstructions at various amounts of low-passed-filtered information and turbulent intensities. We compare our results with those obtained via nudging, a classical equation-informed data assimilation technique. At low Rayleigh numbers, PINNs are able to reconstruct with high precision, comparable to the one achieved with nudging. At high Rayleigh numbers, PINNs outperform nudging and are able to achieve satisfactory reconstruction of the velocity fields only when data for temperature is provided with high spatial and temporal density. When data becomes sparse, the PINNs performance worsens, not only in a point-to-point error sense but also, and contrary to nudging, in a statistical sense, as can be seen in the probability density functions and energy spectra.}, author = {Clark Di Leoni, Patricio and Agasthya, Lokahith N and Buzzicotti, Michele and Biferale, Luca}, issn = {1292-895X}, journal = {The European Physical Journal E}, number = {3}, publisher = {Springer Nature}, title = {{Reconstructing Rayleigh–Bénard flows out of temperature-only measurements using Physics-Informed Neural Networks}}, doi = {10.1140/epje/s10189-023-00276-9}, volume = {46}, year = {2023}, } @article{12830, abstract = {Interstitial fluid (IF) accumulation between embryonic cells is thought to be important for embryo patterning and morphogenesis. Here, we identify a positive mechanical feedback loop between cell migration and IF relocalization and find that it promotes embryonic axis formation during zebrafish gastrulation. We show that anterior axial mesendoderm (prechordal plate [ppl]) cells, moving in between the yolk cell and deep cell tissue to extend the embryonic axis, compress the overlying deep cell layer, thereby causing IF to flow from the deep cell layer to the boundary between the yolk cell and the deep cell layer, directly ahead of the advancing ppl. This IF relocalization, in turn, facilitates ppl cell protrusion formation and migration by opening up the space into which the ppl moves and, thereby, the ability of the ppl to trigger IF relocalization by pushing against the overlying deep cell layer. Thus, embryonic axis formation relies on a hydraulic feedback loop between cell migration and IF relocalization.}, author = {Huljev, Karla and Shamipour, Shayan and Nunes Pinheiro, Diana C and Preusser, Friedrich and Steccari, Irene and Sommer, Christoph M and Naik, Suyash and Heisenberg, Carl-Philipp J}, issn = {1878-1551}, journal = {Developmental Cell}, number = {7}, pages = {582--596.e7}, publisher = {Elsevier}, title = {{A hydraulic feedback loop between mesendoderm cell migration and interstitial fluid relocalization promotes embryonic axis formation in zebrafish}}, doi = {10.1016/j.devcel.2023.02.016}, volume = {58}, year = {2023}, } @article{12831, abstract = {The angulon, a quasiparticle formed by a quantum rotor dressed by the excitations of a many-body bath, can be used to describe an impurity rotating in a fluid or solid environment. Here, we propose a coherent state ansatz in the co-rotating frame, which provides a comprehensive theoretical description of angulons. We reveal the quasiparticle properties, such as energies, quasiparticle weights, and spectral functions, and show that our ansatz yields a persistent decrease in the impurity’s rotational constant due to many-body dressing, which is consistent with experimental observations. From our study, a picture of the angulon emerges as an effective spin interacting with a magnetic field that is self-consistently generated by the molecule’s rotation. Moreover, we discuss rotational spectroscopy, which focuses on the response of rotating molecules to a laser perturbation in the linear response regime. Importantly, we take into account initial-state interactions that have been neglected in prior studies and reveal their impact on the excitation spectrum. To examine the angulon instability regime, we use a single-excitation ansatz and obtain results consistent with experiments, in which a broadening of spectral lines is observed while phonon wings remain highly suppressed due to initial-state interactions.}, author = {Zeng, Zhongda and Yakaboylu, Enderalp and Lemeshko, Mikhail and Shi, Tao and Schmidt, Richard}, issn = {1089-7690}, journal = {The Journal of Chemical Physics}, number = {13}, publisher = {American Institute of Physics}, title = {{Variational theory of angulons and their rotational spectroscopy}}, doi = {10.1063/5.0135893}, volume = {158}, year = {2023}, } @article{12839, abstract = {Universal nonequilibrium properties of isolated quantum systems are typically probed by studying transport of conserved quantities, such as charge or spin, while transport of energy has received considerably less attention. Here, we study infinite-temperature energy transport in the kinetically constrained PXP model describing Rydberg atom quantum simulators. Our state-of-the-art numerical simulations, including exact diagonalization and time-evolving block decimation methods, reveal the existence of two distinct transport regimes. At moderate times, the energy-energy correlation function displays periodic oscillations due to families of eigenstates forming different su(2) representations hidden within the spectrum. These families of eigenstates generalize the quantum many-body scarred states found in previous works and leave an imprint on the infinite-temperature energy transport. At later times, we observe a long-lived superdiffusive transport regime that we attribute to the proximity of a nearby integrable point. While generic strong deformations of the PXP model indeed restore diffusive transport, adding a strong chemical potential intriguingly gives rise to a well-converged superdiffusive exponent z≈3/2. Our results suggest constrained models to be potential hosts of novel transport regimes and call for developing an analytic understanding of their energy transport.}, author = {Ljubotina, Marko and Desaules, Jean Yves and Serbyn, Maksym and Papić, Zlatko}, issn = {2160-3308}, journal = {Physical Review X}, number = {1}, publisher = {American Physical Society}, title = {{Superdiffusive energy transport in kinetically constrained models}}, doi = {10.1103/PhysRevX.13.011033}, volume = {13}, year = {2023}, } @article{12822, abstract = {Gears and cogwheels are elemental components of machines. They restrain degrees of freedom and channel power into a specified motion. Building and powering small-scale cogwheels are key steps toward feasible micro and nanomachinery. Assembly, energy injection, and control are, however, a challenge at the microscale. In contrast with passive gears, whose function is to transmit torques from one to another, interlocking and untethered active gears have the potential to unveil dynamics and functions untapped by externally driven mechanisms. Here, it is shown the assembly and control of a family of self-spinning cogwheels with varying teeth numbers and study the interlocking of multiple cogwheels. The teeth are formed by colloidal microswimmers that power the structure. The cogwheels are autonomous and active, showing persistent rotation. Leveraging the angular momentum of optical vortices, we control the direction of rotation of the cogwheels. The pairs of interlocking and active cogwheels that roll over each other in a random walk and have curvature-dependent mobility are studied. This behavior is leveraged to self-position parts and program microbots, demonstrating the ability to pick up, direct, and release a load. The work constitutes a step toward autonomous machinery with external control as well as (re)programmable microbots and matter.}, author = {Martinet, Quentin and Aubret, Antoine and Palacci, Jérémie A}, issn = {2640-4567}, journal = {Advanced Intelligent Systems}, number = {1}, publisher = {Wiley}, title = {{Rotation control, interlocking, and self‐positioning of active cogwheels}}, doi = {10.1002/aisy.202200129}, volume = {5}, year = {2023}, }