@article{8999,
abstract = {In many basic shear flows, such as pipe, Couette, and channel flow, turbulence does not
arise from an instability of the laminar state, and both dynamical states co-exist. With decreasing flow speed (i.e., decreasing Reynolds number) the fraction of fluid in laminar motion increases while turbulence recedes and eventually the entire flow relaminarizes. The first step towards understanding the nature of this transition is to determine if the phase change is of either first or second order. In the former case, the turbulent fraction would drop discontinuously to zero as the Reynolds number decreases while in the latter the process would be continuous. For Couette flow, the flow between two parallel plates, earlier studies suggest a discontinuous scenario. In the present study we realize a Couette flow between two concentric cylinders which allows studies to be carried out in large aspect ratios and for extensive observation times. The presented measurements show that the transition in this circular Couette geometry is continuous suggesting that former studies were limited by finite size effects. A further characterization of this transition, in particular its relation to the directed percolation universality class, requires even larger system sizes than presently available. },
author = {Avila, Kerstin and Hof, Björn},
issn = {1099-4300},
journal = {Entropy},
number = {1},
publisher = {MDPI},
title = {{Second-order phase transition in counter-rotating taylor-couette flow experiment}},
doi = {10.3390/e23010058},
volume = {23},
year = {2021},
}
@article{9005,
abstract = {Studies on the experimental realization of two-dimensional anyons in terms of quasiparticles have been restricted, so far, to only anyons on the plane. It is known, however, that the geometry and topology of space can have significant effects on quantum statistics for particles moving on it. Here, we have undertaken the first step toward realizing the emerging fractional statistics for particles restricted to move on the sphere instead of on the plane. We show that such a model arises naturally in the context of quantum impurity problems. In particular, we demonstrate a setup in which the lowest-energy spectrum of two linear bosonic or fermionic molecules immersed in a quantum many-particle environment can coincide with the anyonic spectrum on the sphere. This paves the way toward the experimental realization of anyons on the sphere using molecular impurities. Furthermore, since a change in the alignment of the molecules corresponds to the exchange of the particles on the sphere, such a realization reveals a novel type of exclusion principle for molecular impurities, which could also be of use as a powerful technique to measure the statistics parameter. Finally, our approach opens up a simple numerical route to investigate the spectra of many anyons on the sphere. Accordingly, we present the spectrum of two anyons on the sphere in the presence of a Dirac monopole field.},
author = {Brooks, Morris and Lemeshko, Mikhail and Lundholm, D. and Yakaboylu, Enderalp},
issn = {10797114},
journal = {Physical Review Letters},
number = {1},
publisher = {American Physical Society},
title = {{Molecular impurities as a realization of anyons on the two-sphere}},
doi = {10.1103/PhysRevLett.126.015301},
volume = {126},
year = {2021},
}
@article{9006,
abstract = {Cytoplasm is a gel-like crowded environment composed of various macromolecules, organelles, cytoskeletal networks, and cytosol. The structure of the cytoplasm is highly organized and heterogeneous due to the crowding of its constituents and their effective compartmentalization. In such an environment, the diffusive dynamics of the molecules are restricted, an effect that is further amplified by clustering and anchoring of molecules. Despite the crowded nature of the cytoplasm at the microscopic scale, large-scale reorganization of the cytoplasm is essential for important cellular functions, such as cell division and polarization. How such mesoscale reorganization of the cytoplasm is achieved, especially for large cells such as oocytes or syncytial tissues that can span hundreds of micrometers in size, is only beginning to be understood. In this review, we will discuss recent advances in elucidating the molecular, cellular, and biophysical mechanisms by which the cytoskeleton drives cytoplasmic reorganization across different scales, structures, and species.},
author = {Shamipour, Shayan and Caballero Mancebo, Silvia and Heisenberg, Carl-Philipp J},
issn = {18781551},
journal = {Developmental Cell},
number = {2},
pages = {P213--226},
publisher = {Elsevier},
title = {{Cytoplasm's got moves}},
doi = {10.1016/j.devcel.2020.12.002},
volume = {56},
year = {2021},
}
@article{9009,
abstract = {Recent advancements in live cell imaging technologies have identified the phenomenon of intracellular propagation of late apoptotic events, such as cytochrome c release and caspase activation. The mechanism, prevalence, and speed of apoptosis propagation remain unclear. Additionally, no studies have demonstrated propagation of the pro-apoptotic protein, BAX. To evaluate the role of BAX in intracellular apoptotic propagation, we used high speed live-cell imaging to visualize fluorescently tagged-BAX recruitment to mitochondria in four immortalized cell lines. We show that propagation of mitochondrial BAX recruitment occurs in parallel to cytochrome c and SMAC/Diablo release and is affected by cellular morphology, such that cells with processes are more likely to exhibit propagation. The initiation of propagation events is most prevalent in the distal tips of processes, while the rate of propagation is influenced by the 2-dimensional width of the process. Propagation was rarely observed in the cell soma, which exhibited near synchronous recruitment of BAX. Propagation velocity is not affected by mitochondrial volume in segments of processes, but is negatively affected by mitochondrial density. There was no evidence of a propagating wave of increased levels of intracellular calcium ions. Alternatively, we did observe a uniform increase in superoxide build-up in cellular mitochondria, which was released as a propagating wave simultaneously with the propagating recruitment of BAX to the mitochondrial outer membrane.},
author = {Grosser, Joshua A. and Maes, Margaret E and Nickells, Robert W.},
issn = {1573-675X},
journal = {Apoptosis},
number = {2},
pages = {132--145},
publisher = {Springer Nature},
title = {{Characteristics of intracellular propagation of mitochondrial BAX recruitment during apoptosis}},
doi = {10.1007/s10495-020-01654-w},
volume = {26},
year = {2021},
}
@article{9020,
abstract = {We study dynamics and thermodynamics of ion transport in narrow, water-filled channels, considered as effective 1D Coulomb systems. The long range nature of the inter-ion interactions comes about due to the dielectric constants mismatch between the water and the surrounding medium, confining the electric filed to stay mostly within the water-filled channel. Statistical mechanics of such Coulomb systems is dominated by entropic effects which may be accurately accounted for by mapping onto an effective quantum mechanics. In presence of multivalent ions the corresponding quantum mechanics appears to be non-Hermitian. In this review we discuss a framework for semiclassical calculations for the effective non-Hermitian Hamiltonians. Non-Hermiticity elevates WKB action integrals from the real line to closed cycles on a complex Riemann surfaces where direct calculations are not attainable. We circumvent this issue by applying tools from algebraic topology, such as the Picard-Fuchs equation. We discuss how its solutions relate to the thermodynamics and correlation functions of multivalent solutions within narrow, water-filled channels. },
author = {Gulden, Tobias and Kamenev, Alex},
issn = {1099-4300},
journal = {Entropy},
number = {1},
publisher = {MDPI},
title = {{Dynamics of ion channels via non-hermitian quantum mechanics}},
doi = {10.3390/e23010125},
volume = {23},
year = {2021},
}