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  1. Article ; Online: Noise and thermal depinning of Wigner crystals.

    Reichhardt, C / Reichhardt, C J O

    Journal of physics. Condensed matter : an Institute of Physics journal

    2023  Volume 35, Issue 32

    Abstract: We examine changes in the depinning threshold and conduction noise fluctuations for driven Wigner crystals in the presence of quenched disorder. At low temperatures there is a well defined depinning threshold and a strong peak in the noise power with1/ ... ...

    Abstract We examine changes in the depinning threshold and conduction noise fluctuations for driven Wigner crystals in the presence of quenched disorder. At low temperatures there is a well defined depinning threshold and a strong peak in the noise power with1/fnoise characteristics. At higher temperatures, the depinning threshold shifts to lower drives and the noise, which is also reduced in power, becomes more white in character. At lower temperatures, a washboard frequency appears when the system depins elastically or forms a moving smectic state; however, this washboard signal is strongly reduced for higher temperatures and completely disappears above the melting temperature of a system without quenched disorder. Our results are in good agreement with recent transport and noise studies for systems where electron crystal depinning is believed to arise, and also show how noise can be used to distinguish between crystal, glass, and liquid phases.
    Language English
    Publishing date 2023-05-16
    Publishing country England
    Document type Journal Article
    ZDB-ID 1472968-4
    ISSN 1361-648X ; 0953-8984
    ISSN (online) 1361-648X
    ISSN 0953-8984
    DOI 10.1088/1361-648X/acd218
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  2. Article ; Online: Vortex Lattices in Active Nematics with Periodic Obstacle Arrays.

    Schimming, Cody D / Reichhardt, C J O / Reichhardt, C

    Physical review letters

    2024  Volume 132, Issue 1, Page(s) 18301

    Abstract: We numerically model a two-dimensional active nematic confined by a periodic array of fixed obstacles. Even in the passive nematic, the appearance of topological defects is unavoidable due to planar anchoring by the obstacle surfaces. We show that a ... ...

    Abstract We numerically model a two-dimensional active nematic confined by a periodic array of fixed obstacles. Even in the passive nematic, the appearance of topological defects is unavoidable due to planar anchoring by the obstacle surfaces. We show that a vortex lattice state emerges as activity is increased, and that this lattice may be tuned from "ferromagnetic" to "antiferromagnetic" by varying the gap size between obstacles. We map the rich variety of states exhibited by the system as a function of distance between obstacles and activity, including a pinned defect state, motile defects, the vortex lattice, and active turbulence. We demonstrate that the flows in the active turbulent phase can be tuned by the presence of obstacles, and explore the effects of a frustrated lattice geometry on the vortex lattice phase.
    Language English
    Publishing date 2024-01-19
    Publishing country United States
    Document type Journal Article
    ZDB-ID 208853-8
    ISSN 1079-7114 ; 0031-9007
    ISSN (online) 1079-7114
    ISSN 0031-9007
    DOI 10.1103/PhysRevLett.132.018301
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  3. Article ; Online: The Pseudomonas aeruginosa Biofilm Matrix Protein CdrA Has Similarities to Other Fibrillar Adhesin Proteins.

    Reichhardt, Courtney

    Journal of bacteriology

    2023  Volume 205, Issue 5, Page(s) e0001923

    Abstract: The ability of bacteria to adhere to each other and both biotic and abiotic surfaces is key to biofilm formation, and one way that bacteria adhere is using fibrillar adhesins. Fibrillar adhesins share several key characteristics, including (i) they are ... ...

    Abstract The ability of bacteria to adhere to each other and both biotic and abiotic surfaces is key to biofilm formation, and one way that bacteria adhere is using fibrillar adhesins. Fibrillar adhesins share several key characteristics, including (i) they are extracellular, surface-associated proteins, (ii) they contain an adhesive domain as well as a repetitive stalk domain, and (iii) they are either a monomer or homotrimer (i.e., identical, coiled-coil) of a high molecular weight protein. Pseudomonas aeruginosa uses the fibrillar adhesin called CdrA to promote bacterial aggregation and biofilm formation. Here, the current literature on CdrA is reviewed, including its transcriptional and posttranslational regulation by the second messenger c-di-GMP as well as what is known about its structure and ability to interact with other molecules. I highlight its similarities to other fibrillar adhesins and discuss open questions that remain to be answered toward a better understanding of CdrA.
    MeSH term(s) Extracellular Polymeric Substance Matrix/metabolism ; Pseudomonas aeruginosa/metabolism ; Biofilms ; Cyclic GMP/metabolism ; Adhesins, Bacterial/metabolism ; Bacteria/metabolism ; Bacterial Proteins/genetics ; Bacterial Proteins/metabolism ; Gene Expression Regulation, Bacterial
    Chemical Substances Cyclic GMP (H2D2X058MU) ; Adhesins, Bacterial ; Bacterial Proteins
    Language English
    Publishing date 2023-04-26
    Publishing country United States
    Document type Journal Article ; Review
    ZDB-ID 2968-3
    ISSN 1098-5530 ; 0021-9193
    ISSN (online) 1098-5530
    ISSN 0021-9193
    DOI 10.1128/jb.00019-23
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    In stock of ZB MED Cologne/Königswinter

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    Je nach Verfügbarkeit (siehe Angabe bei Bestand)
    bis Jg. 2021: Bestellungen von Artikeln über das Online-Bestellformular
    ab Jg. 2022: Lesesaal (EG)

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  4. Article ; Online: Reversible to irreversible transitions for cyclically driven particles on periodic obstacle arrays.

    Reichhardt, C / Reichhardt, C J O

    The Journal of chemical physics

    2022  Volume 156, Issue 12, Page(s) 124901

    Abstract: We examine the collective dynamics of disks moving through a square array of obstacles under cyclic square wave driving. Below a critical density, we find that the system organizes into a reversible state in which the disks return to the same positions ... ...

    Abstract We examine the collective dynamics of disks moving through a square array of obstacles under cyclic square wave driving. Below a critical density, we find that the system organizes into a reversible state in which the disks return to the same positions at the end of every drive cycle. Above this density, the dynamics are irreversible and the disks do not return to the same positions after each cycle. The critical density depends strongly on the angle θ between the driving direction and a symmetry axis of the obstacle array, with the highest critical densities appearing at commensurate angles such as θ = 0° and θ = 45° and the lowest critical densities falling at θ = arctan (0.618), the inverse of the golden ratio, where the flow is the most degenerate. As the density increases, the number of cycles required to reach a reversible state grows as a power law with an exponent near ν = 1.36, similar to what is found in periodically driven colloidal and superconducting vortex systems.
    Language English
    Publishing date 2022-04-01
    Publishing country United States
    Document type Journal Article
    ZDB-ID 3113-6
    ISSN 1089-7690 ; 0021-9606
    ISSN (online) 1089-7690
    ISSN 0021-9606
    DOI 10.1063/5.0087916
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    In stock of ZB MED Bonn / Germany

    Z 4' 49/16: Show issues

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  5. Article ; Online: Motility-induced phase separation and frustration in active matter swarmalators.

    Adorjáni, B / Libál, A / Reichhardt, C / Reichhardt, C J O

    Physical review. E

    2024  Volume 109, Issue 2-1, Page(s) 24607

    Abstract: We introduce a two dimensional system of active matter swarmalators composed of elastically interacting run-and-tumble active disks with an internal parameter ϕ_{i}. The disks experience an additional attractive or repulsive force with neighboring disks ... ...

    Abstract We introduce a two dimensional system of active matter swarmalators composed of elastically interacting run-and-tumble active disks with an internal parameter ϕ_{i}. The disks experience an additional attractive or repulsive force with neighboring disks depending upon their relative difference in ϕ_{i}, making them similar to swarmalators used in robotic systems. In the absence of the internal parameter, the system forms a motility-induced phase separated (MIPS) state, but when the swarmalator interactions are present, a wide variety of other active phases appear depending upon whether the interaction is attractive or repulsive and whether the particles act to synchronize or ant-synchronize their internal parameter values. These phases include a gas-free gel regime, arrested clusters, a labyrinthine state, a regular MIPS state, a frustrated MIPS state for attractive antisynchronization, and a superlattice MIPS state for attractive synchronization.
    Language English
    Publishing date 2024-03-15
    Publishing country United States
    Document type Journal Article
    ZDB-ID 2844562-4
    ISSN 2470-0053 ; 2470-0045
    ISSN (online) 2470-0053
    ISSN 2470-0045
    DOI 10.1103/PhysRevE.109.024607
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  6. Article ; Online: Friction-mediated phase transition in confined active nematics.

    Schimming, Cody D / Reichhardt, C J O / Reichhardt, C

    Physical review. E

    2023  Volume 108, Issue 1, Page(s) L012602

    Abstract: Using a minimal continuum model, we investigate the interplay between circular confinement and substrate friction in active nematics. Upon increasing the friction from low to high, we observe a dynamical phase transition from a circulating flow phase to ... ...

    Abstract Using a minimal continuum model, we investigate the interplay between circular confinement and substrate friction in active nematics. Upon increasing the friction from low to high, we observe a dynamical phase transition from a circulating flow phase to an anisotropic flow phase in which the flow tends to align perpendicular to the nematic director at the boundary. We demonstrate that both the flow structure and dynamic correlations in the latter phase differ from those of an unconfined, active turbulent system and may be controlled by the prescribed nematic boundary conditions. Our results show that substrate friction and geometric confinement act as valuable control parameters in active nematics.
    Language English
    Publishing date 2023-07-27
    Publishing country United States
    Document type Journal Article
    ZDB-ID 2844562-4
    ISSN 2470-0053 ; 2470-0045
    ISSN (online) 2470-0053
    ISSN 2470-0045
    DOI 10.1103/PhysRevE.108.L012602
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  7. Book ; Online: Noise and Thermal Depinning of Wigner Crystals

    Reichhardt, C. / Reichhardt, C. J. O.

    2023  

    Abstract: We examine changes in the depinning threshold and conduction noise fluctuations for driven Wigner crystals in the presence of quenched disorder. At low temperatures there is a well defined depinning threshold and a strong peak in the noise power with $1/ ... ...

    Abstract We examine changes in the depinning threshold and conduction noise fluctuations for driven Wigner crystals in the presence of quenched disorder. At low temperatures there is a well defined depinning threshold and a strong peak in the noise power with $1/f$ noise characteristics. At higher temperatures, the depinning threshold shifts to lower drives and the noise, which is also reduced in power, becomes more white in character. At lower temperatures, a washboard frequency appears when the system depins elastically or forms a moving smectic state; however, this washboard signal is strongly reduced for higher temperatures and completely disappears above the melting temperature of a system without quenched disorder. Our results are in good agreement with recent transport and noise studies for systems where electron crystal depinning is believed to arise, and also show how noise can be used to distinguish between crystal, glass, and liquid phases.

    Comment: 23 pages, 15 postscript figures
    Keywords Condensed Matter - Mesoscale and Nanoscale Physics ; Condensed Matter - Strongly Correlated Electrons
    Subject code 612
    Publishing date 2023-01-26
    Publishing country us
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  8. Book ; Online: Peak Effect, Melting, and Transport in Skyrmion Crystals

    Reichhardt, C. / Reichhardt, C. J. O.

    2023  

    Abstract: We numerically examine the transport of skyrmions driven over weak random quenched disorder using a modified Thiele approach that includes the thermal softening of skyrmion pairwise interactions introduced by Wang et al., Phys. Rev. Appl. 18, 044024 ( ... ...

    Abstract We numerically examine the transport of skyrmions driven over weak random quenched disorder using a modified Thiele approach that includes the thermal softening of skyrmion pairwise interactions introduced by Wang et al., Phys. Rev. Appl. 18, 044024 (2022). The depinning transition is elastic at low temperatures but becomes plastic with a reduced threshold at higher temperatures due to the competition between thermal creep and thermal softening, indicating a temperature-induced order to disorder transition into a glass state. The resulting non-monotonic critical depinning forces and crossing of the velocity-force curves are similar to what is observed in the peak effect for type-II superconducting vortex lattices, where the softening of vortex-vortex interactions with temperature leads to an order-disorder transition. For low skyrmion densities the peak effect is absent since the system is always in a disordered state. We map the dynamical phase transition as a function of temperature, density, drive, and materials parameters, and show that the signatures are similar to those of the superconducting peak effect. Our results are consistent with recent experiments.

    Comment: 12 pages, 15 postscript figures
    Keywords Condensed Matter - Mesoscale and Nanoscale Physics
    Subject code 612
    Publishing date 2023-04-01
    Publishing country us
    Document type Book ; Online
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  9. Book ; Online: The Kibble-Zurek Scenario and Coarsening Across Nonequilibrium Phase Transitions in Driven Vortices and Skyrmions

    Reichhardt, C. / Reichhardt, C. J. O.

    2023  

    Abstract: We investigate the topological defect populations for superconducting vortices and magnetic skyrmions on random pinning substrates under driving amplitudes that are swept at different rates or suddenly quenched. When the substrate pinning is sufficiently ...

    Abstract We investigate the topological defect populations for superconducting vortices and magnetic skyrmions on random pinning substrates under driving amplitudes that are swept at different rates or suddenly quenched. When the substrate pinning is sufficiently strong, the system exhibits a nonequilibrium phase transition at a critical drive into a more topologically ordered state. We examine the number of topological defects that remain as we cross the ordering transition at different rates. In the vortex case, the system dynamically orders into a moving smectic, and the Kibble-Zurek scaling hypothesis gives exponents consistent with directed percolation. Due to their strong Magnus force, the skyrmions dynamically order into an isotropic crystal, producing different Kibble-Zurek scaling exponents that are more consistent with coarsening. We argue that in the skyrmion crystal, the topological defects can both climb and glide, facilitating coarsening, whereas in the vortex smectic state, the defects cannot climb and coarsening is suppressed. We also examine pulsed driving across the ordering transition and find that the defect population on the ordered side of the transition decreases with time as a power law, indicating that coarsening can occur across nonequilibrium phase transitions. Our results should be general to a wide class of nonequilibrium systems driven over random disorder where there are well-defined topological defects.

    Comment: 10 pages, 10 postscript figures
    Keywords Condensed Matter - Mesoscale and Nanoscale Physics ; Condensed Matter - Statistical Mechanics ; Condensed Matter - Superconductivity
    Subject code 612
    Publishing date 2023-07-05
    Publishing country us
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  10. Article ; Online: Active matter commensuration and frustration effects on periodic substrates.

    Reichhardt, C / Reichhardt, C J O

    Physical review. E

    2021  Volume 103, Issue 2-1, Page(s) 22602

    Abstract: We show that self-driven particles coupled to a periodic obstacle array exhibit active matter commensuration effects that are absent in the Brownian limit. As the obstacle size is varied for sufficiently large activity, a series of commensuration effects ...

    Abstract We show that self-driven particles coupled to a periodic obstacle array exhibit active matter commensuration effects that are absent in the Brownian limit. As the obstacle size is varied for sufficiently large activity, a series of commensuration effects appear in which the motility induced phase separation produces commensurate crystalline states, while for other obstacle sizes we find frustrated or amorphous states. The commensuration effects are associated with peaks in the amount of sixfold ordering and the maximum cluster size. When a drift force is added to the system, the mobility contains peaks and dips similar to those found in transport studies for commensuration effects in superconducting vortices and colloidal particles.
    Language English
    Publishing date 2021-03-18
    Publishing country United States
    Document type Journal Article
    ZDB-ID 2844562-4
    ISSN 2470-0053 ; 2470-0045
    ISSN (online) 2470-0053
    ISSN 2470-0045
    DOI 10.1103/PhysRevE.103.022602
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