# gst: apropos of diffusive anomalies, anomalous diffusion of active Brownian particles in responsive elastic gels.

Here, AA << examine via extensive computer simulations the dynamics of SPPs (self-propelled particles) in deformable gellike structures responsive to thermal fluctuations. (AA) treat tracer particles comparable to and larger than the mesh size of the gel. (They) observe distinct trapping events of active tracers at relatively short times, leading to subdiffusion; it is followed by an escape from meshwork-induced traps due to the flexibility of the network, resulting in superdiffusion. >>

AA << thus find crossovers between different transport regimes. (They) also find pronounced nonergodicity in the dynamics of SPPs and non-Gaussianity at intermediate times. The distributions of trapping times of the tracers escaping from “cages” in (..)  quasiperiodic gel often reveal the existence of two distinct timescales in the dynamics. At high activity of the tracers these timescales become comparable. >>

<< Furthermore, (AA) find that the mean waiting time exhibits a power-law dependence on the activity of SPPs (in terms of their Péclet number). (Their) results additionally showcase both exponential and nonexponential trapping events at high activities. Extensions of this setup are possible, with the factors such as anisotropy of the particles, different topologies of the gel network, and various interactions between the particles (also of a nonlocal nature) to be considered. >>

Koushik Goswami, Andrey G. Cherstvy, et al. Anomalous diffusion of active Brownian particles in responsive elastic gels: Nonergodicity, non-Gaussianity, and distributions of trapping times. Phys. Rev. E 110, 044609. Oct 29, 2024.

https://journals.aps.org/pre/abstract/10.1103/PhysRevE.110.044609

Also: particle, random, escape, network, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, particle, random, random walks, escape, network

# gst: underdamped and overdamped scenarios of a one-dimensional inertial run-and-tumble particle

AA << study the nonequilibrium stationary state of a one-dimensional inertial run-and-tumble particle  trapped in a harmonic potential. (AA) find that the presence of inertia leads to two distinct dynamical scenarios, namely, overdamped and underdamped, characterized by the relative strength of the viscous and the trap timescales. >>

️

<< in the underdamped regime, both the position and velocity undergo transitions from a novel multipeaked structure in the strongly active limit to a single-peaked Gaussian-like distribution in the passive limit. On the other hand, in the overdamped scenario, the position distribution shows a transition from a U shape to a dome shape, as activity is decreased. Interestingly, the velocity distribution in the overdamped scenario shows two transitions—from a single-peaked shape with an algebraic divergence at the origin in the strongly active regime to a double-peaked one in the moderately active regime to a dome-shaped one in the passive regime. >>️

Debraj Dutta, Anupam Kundu, et al. Harmonically trapped inertial run-and-tumble particle in one dimension. Phys. Rev. E 110, 044107. Oct 4, 2024. 

https://journals.aps.org/pre/abstract/10.1103/PhysRevE.110.044107

Also: particle, transition, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, particle, transition 

# gst: apropos of breaking mechanisms, crack of a floating particle raft caused by waves.

<< When particles of a few tens of microns are spread on the surface of water, they aggregate under the action of capillary forces and form a thin floating membrane, a particle raft. >>

<< For a sufficiently strong wave amplitude, the raft breaks up progressively by developing cracks and producing fragments whose sizes decrease on a timescale long compared to the period of the wave. (AA)  characterize the breaking mechanisms.  >>️️

<< The visual appearance of the fragments distributed in size and surrounded by open water bears a notable resemblance to the floes produced by the fracturing of sea ice by waves in the polar oceans. Fragmentation concepts and morphological tools built for sea ice floes can be applied to (AA) macroscopic analog, on which the entire dynamic evolution is accessible. However, the mechanics of the two systems differ, as (AA) particle raft breaks due to the viscous stresses, whereas the sea ice fractures due to its bending by the waves. >>️

Louis Saddier, Ambre Palotai, et al. Breaking of a floating particle raft by water waves. Phys. Rev. Fluids 9, 094302. Sep 27, 2024.

https://journals.aps.org/prfluids/abstract/10.1103/PhysRevFluids.9.094302 

Also: 'crack', 'particle', in  https://www.inkgmr.net/kwrds.html 

Also: 'break' in  https://flashontrack.blogspot.com/search?q=break

Also: 'raft' in  https://flashontrack.blogspot.com/search?q=raft

Also: 'zattera' (quasi-stochastic poetry) in  https://inkpi.blogspot.com/search?q=zattera  'randa' (quasi-stochastic poetry) in https://inkpi.blogspot.com/search?q=randa

Keywords: gst, crack, break, particle, raft, particle raft

# gst: apropos of inertial particles, they dispersion in turbulent canopy flows with buoyant and nonbuoyant plumes.

<< In an idealized “wind-driven” model system, (AA) consider the impact of plume buoyancy, plume momentum, and canopy turbulence on the downstream transport of particles in the wake of a canopy, and in particular the mean and standard deviation of the distribution of landing sites. >>

<< In a first set of experiments, particles were released with a fixed starting elevation above the plumes' upper boundaries, such that the particles were not lofted by the plume. In these cases, observations suggest that plumes have a role in extending particles' streamwise transport by delaying their downward transport. The plumes also have a strong role in increasing absolute dispersion of the particles, although less so when dispersion is normalized by distance traveled. While canopy turbulence alone significantly increases particle dispersion, in the presence of the plume its impact is more limited. Canopy turbulence was also found to cause shorter mean landing positions. >>

<< In a second set of experiments, particles were released at the plume source/outlet such that their initial vertical momentum was provided by the plume's momentum and buoyancy. In these cases, the impact of canopy turbulence on particle transport is observed more distinctly. The canopy coherent structures introduce a mechanical instability to the plume, which manifests as vertical oscillatory motions that lead to variability in the particles' initial conditions and, therefore, trajectories. This leads to particles settling at both shorter and longer downstream distances. >>

Hayoon Chung, Laura K. C. Sunberg, et al. Dispersion of inertial particles in turbulent canopy flows with buoyant and nonbuoyant plumes. Phys. Rev. Fluids 9, 093801. Sept 25, 2024.

https://journals.aps.org/prfluids/abstract/10.1103/PhysRevFluids.9.093801  

Also: particle, turbulence, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, particle, turbulence

# gst: quantum jamming on the macroscopic scale

 << In the presence of kinetic constraints, quasiparticles describing the behavior of an ordered arrangement of quantum spins can get “stuck” as their density increases. Because of its similarity to the formation of amorphous solids, this situation can be interpreted as the quantum analog of jamming. Jammed states are intrinsically unstable and small perturbations produce unusual nonequilibrium dynamics. >> 

 AA << show that quantum jamming is a mechanism to make microscopic phenomena visible at a macroscopic scale: A single impurity produces a permanent change in the state, and a few impurities leave an imprint of their scattering properties and bound states. >> 

Maurizio Fagotti. Quantum Jamming Brings Quantum Mechanics to Macroscopic Scales. Phys. Rev. X 14, 021015. Apr 23, 2024.

https://journals.aps.org/prx/abstract/10.1103/PhysRevX.14.021015

Also: particle, jamming, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, particle, jamming

# gst: apropos of collective behaviors, a visual model to reproduces swarming, schooling, and milling.

<< Animal collective behavior is often modeled with self-propelled particles, assuming each individual has “omniscient” knowledge of its neighbors. Yet, neighbors may be hidden from view and we do not know the effect of this information loss. To address this question, (AA) propose a visual model of collective behavior where each particle moves according to bioplausible visual cues, in particular the optic flow. This visual model successfully reproduces three classical collective behaviors: swarming (no orientational order), schooling (high orientational order), and milling (the group coordinately swirls in a circular pattern). >>️

Diego Castro, Franck Ruffier, Christophe Eloy. Modeling collective behaviors from optic flow and retinal cues. Phys. Rev. Research 6, 023016. Apr 4, 2024. 

https://journals.aps.org/prresearch/abstract/10.1103/PhysRevResearch.6.023016

Also: swarm, flock, behav, particle, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, swarming, flocking, behavior, particle, self-propelled particles

# gst: apropos of evaporation, puncturing of active drops

<< By virtue of self-propulsion, active particles impart intricate stresses to the background fluids. (..) this active stress can be utilized to greatly control evaporation dynamics of active drops. >>

AA << discover a new phenomenon of puncturing of the active drops, where the air-liquid interface of the drop undergoes spontaneous tearing and there occurs a formation of a new three-phase contact line due to the liquid-air interface hitting the liquid-solid interface through evaporation-driven mass loss. Post puncturing, (AA) see an inside-out evaporation of the drop, where the new contact line sweeps towards the pinned outer contact line of the drops, contrasting regular drops that straightaway shrink to zero volume with self-similar shape. >>

<< Furthermore, (..) the activity inside the drops can manipulate the three-phase contact-line dynamics, which for contractile drops can result in an up to 50% enhanced lifetime of the drop and 33% quicker evaporation for extensile drops. By analyzing the flux distribution inside the drop, (AA) gain insights on nonintuitive deposition patterns (e.g., ring galaxy type deposits that demonstrate controllable spatial gradients in the concentrations of the deposited particles) of active particles, which are oftentimes biological substances or bimetallic nanoparticles of interest. >>

Ghansham Rajendrasingh Chandel, Vishal Sankar Sivasankar, Siddhartha Das. Evaporation of active drops: Puncturing drops and particle deposits of ring galaxy patterns. Phys. Rev. Fluids 9, 033603. Mar 27, 2024. 

https://journals.aps.org/prfluids/abstract/10.1103/PhysRevFluids.9.033603

Also: drop, particle, evaporation, transition, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, drop, particle, evaporation, transition, drop interactions, droplet, droploid

# gst: soft and stiff modes in colloidal particle networks

<< Floppy microscale spring networks are widely studied in theory and simulations, but no well-controlled experimental system currently exists. >> 

AA << show that square lattices consisting of colloid-supported lipid bilayers functionalized with DNA linkers act as microscale floppy spring networks. (AA) extract their normal modes by inverting the particle displacement correlation matrix, showing the emergence of a spectrum of soft modes with low effective stiffness in addition to stiff modes that derive from linker interactions. >>

<< Evaluation of the softest mode, a uniform shear mode, reveals that shear stiffness decreases with lattice size. >>

 AA << results reveal the importance of entropic steric effects. >>

️

Julio Melio, Silke E. Henkes, Daniela J. Kraft. Soft and Stiff Normal Modes in Floppy Colloidal Square Lattices. Phys. Rev. Lett. 132, 078202. Feb 14, 2024. 

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.132.078202

Also: particle, nano, colloids, network, in https://www.inkgmr.net/kwrds.html

Keywords: gst, particle, nano, colloids, network, colloidal network

# gst: transitions in disordered medium.

AA << study computationally the dynamics of forced, Brownian particles through a disordered system. As the concentration of mobile particles and/or fixed obstacles increase, (AA) characterize the different regimes of flow and address how clogging develops. >>️

AA << show that clogging is preceded by a wide region of anomalous transport, characterized by a power law decay of intermittent bursts. (..) this abnormal flow region is characterized by a coexistence between mobile and arrested particles, and their relative populations change smoothly as clogging is approached. >>

️

Sergi G. Leyva, Ignacio Pagonabarraga. Clogging transition and anomalous transport in driven suspensions in a disordered medium. Phys. Rev. E 109, 014618. Jan 31, 2024.

https://journals.aps.org/pre/abstract/10.1103/PhysRevE.109.014618

img:  https://twitter.com/PhysRevE/status/1753068208586711072   

Also: transition, particle, disorder, in https://www.inkgmr.net/kwrds.html

Keywords: gst, transition, particle, disorder

# gst: intertwining order, disorder, and hierarchy

<< Nature hosts a wealth of materials showcasing intricate structures intertwining order, disorder, and hierarchy, delivering resilient multifunctionality surpassing perfect crystals or simplistic disordered materials. The engineering of such materials through nanoparticle assembly represents a burgeoning field, poised with potential to yield sustainable material systems rivaling or exceeding biological functionalities. >>

AA << review delineates the fundamental concept of complexity in the context of nanoscale materials. >>

Xiaoming Mao, Nicholas Kotov. Complexity, Disorder, and Functionality of Nanoscale Materials. arXiv: 2401.09567v1 [cond-mat.soft]. Jan 17, 2024. 

https://arxiv.org/abs/2401.09567

Also: nano, particle, order, disorder, in  https://www.inkgmr.net/kwrds.html

Keywords: nano, particle, order, disorder 

# gst: pulsating active matter.

<< the mechanical pulsation of locally synchronized particles is a generic route to propagate deformation waves. >>

️

AA << consider a model of dense repulsive particles whose activity drives periodic change in size of each individual. >>️

They << show that the competition between repulsion and synchronization triggers an instability which promotes a wealth of dynamical patterns, ranging from spiral waves to defect turbulence. >>️

Yiwei Zhang, Etienne Fodor. Pulsating Active Matter. Phys. Rev. Lett. 131, 238302. Dec 8, 2023. 

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.131.238302

Also: waves, particle, transition, instability, turbulence, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, waves, particle, transition, instability, turbulence

# gst: scanning inside a granular raft

<< Rheology of macroscopic particle-laden interfaces, called “granular rafts,” has been experimentally studied in the simple shear configuration.  >>️

<< Close to the walls of the rheometer cell, one can observe regions of large local shear rate while in the middle of the cell a quasistatic zone exists. >>

<< Measuring the probability density functions of the instantaneous local shear rate, (AA) provide evidence of a balance between positive and negative instantaneous local shear rate. This behavior is the signature of a quasistatic region inside the granular raft. >>️

️

J. Lalieu, A. Seguin, G. Gauthier. Rheology of granular rafts. Phys. Rev. E 107, 064901. June 29, 2023.

https://journals.aps.org/pre/abstract/10.1103/PhysRevE.107.064901

Also: Bavand Keshavarz, Michela Geri. Mandelbrot granular raft. Phys. Rev. Fluids 8, 110506. Nov 16, 2023.

https://journals.aps.org/prfluids/abstract/10.1103/PhysRevFluids.8.110506

Also: grain, particle, in https://www.inkgmr.net/kwrds.html 

Also: << l'invasiva scorribanda /

sull' oramai alla deriva lacerata randa. >>️ in: Schismi da vibrati di tangone. Notes. March 23, 2005. (quasi-stochastic poetry)

https://inkpi.blogspot.com/2005/03/1608b-schismi-da-vibrati-di-tangone.html

Keywords: gst, raft, particle, grain, granular raft, life

# gst: local elastic properties of strongly disordered matter

<< The local elastic properties of strongly disordered material are investigated using the theory of correlated random matrices. A significant increase in stiffness is shown in the interfacial region, the thickness of which depends on the strength of disorder. It is shown that this effect plays a crucial role in nanocomposites, in which interfacial regions are formed around each nanoparticle. >>️

D. A. Conyuh, A. A. Semenov, Y. M. Beltukov. Effective elastic moduli of composites with a strongly disordered host material. Phys. Rev. E 108, 045004. Oct 20, 2023. 

https://journals.aps.org/pre/abstract/10.1103/PhysRevE.108.045004

Also: elastic, noise, particle, nano, in https://www.inkgmr.net/kwrds.html

Keywords: gst, elastic, noise, particle, nano

# gst: emergence of self-organizing zigzag patterns among (magnetic) particles suspended in a liquid

<< When molecules or bacteria organize into a long-range pattern, researchers want to understand how the microscopic interactions lead to the macroscopic order. (AA) observed such self-organization in magnetic particles suspended in a liquid and subjected to an oscillating magnetic field. Through experiments and simulations, the team showed that the resulting zigzag pattern is explained by the fluid flow generated around the oscillating particles, not by any details of the particles or the applied field. Similar zigzag patterns have also been seen in charged colloids subjected to oscillating electric fields, so the explanation may cover a range of particle systems. The researchers also believe that understanding and controlling the effect could lead to useful applications in microfluidics devices. >>️

David Ehrenstein. Self-Organized Zigzags from Fluid Flow. Physics 16, 138. Aug 11, 2023.

https://physics.aps.org/articles/v16/138

Gaspard Junot, Marco De Corato, Pietro Tierno. Large Scale Zigzag Pattern Emerging from Circulating Active Shakers. Phys. Rev. Lett. 131, 068301. Aug 11, 2023. 

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.131.068301

Also: particle, self-assembly, chiral, behav, in: https://www.inkgmr.net/kwrds.html  

Keywords: gst, behavior, particle, self-assembly, self-organization, chiral, active shakers, squirmers, alternating chirality

# gst: stochastic resonance mediated by optimal noise level values; transport of colloidal particles induced by substrate concentration oscillations.

AA << show the existence of a  stochastic resonant regime in the transport of active colloidal particles under confinement. The periodic addition of substrate to the system causes the spectral amplification to exhibit a maximum for an optimal noise level value. The consequence of this is that particles can travel longer distances with lower fuel consumption. The stochastic resonance phenomenon found allows the identification of optimal scenarios for the transport of active particles, enabling them to reach regions that are otherwise difficult to access, and may therefore find applications in transport. >>️

J. D. Torrenegra-Rico, A. Arango-Restrepo, J. M. Rubi. Optimal transport of active particles induced by substrate concentration oscillations. Phys. Rev. E 108, 014134. July 28, 2023.

https://journals.aps.org/pre/abstract/10.1103/PhysRevE.108.014134

Img: https://twitter.com/PhysRevE/status/1687119409096089602

Also: particle, colloids, noise, in:  https://www.inkgmr.net/kwrds.html

Keywords: gst, particle, colloids, noise, stochastic resonance, substrate oscillation

# gst: inertial particles within co-rotating dusty vortices

 << dispersed particles with moderate inertia cause the vortex pair to push apart to a separation nearly twice as large as the initial separation. >>

 

 << antisymmetric vorticity generated by particles flung out of the rotational cores causes the vortex pair repulsion. Eventually, the two dusty vortices merge into a single vortex with most particles accumulating outside the core similar to the dusty Lamb-Oseen vortex described in Shuai & Kasbaoui (2022) >>

 

 << For weakly inertial particles, (AA) find that the merger dynamics follow the same mechanics as those of a single-phase flow, albeit with a density that must be adjusted to match the mixture density. >>

 

<< Lastly, highly inertial particles tend to fragment the vortex cores leading to murky merger dynamics. >>

Shuai Shuai, Anubhab Roy, M. Houssem Kasbaoui. The merger of co-rotating vortices in dusty flows. arXiv: 2307.05413v1 [physics.flu-dyn]. Jul 11, 2023. 

https://arxiv.org/abs/2307.05413

Also: particle, vortex, in https://www.inkgmr.net/kwrds.html

Keywords: gst, particle, vortex 

# gst: the effects of order- disorder on a system of swarmalators that move on a one-dimensional ring.

<< Swarmalators are phase oscillators that cluster in space, like fireflies flashing on a swarm to attract mates. >>

<< In this work, (AA) explore the effects of disorder induced by phase frustration on a system of Swarmalators that move on a one-dimensional ring. >>

They find << numerically and analytically, the ordered and disordered states that emerge in the system. The active states, not present in the model without disorder, resemble states found previously in numerical studies for the 2D Swarmalators system. One of these states, in particular, shows similarities to turbulence generated in a flattened media. (AA) show that all ordered states can be generated for any values of the coupling constants by tuning the phase frustration parameters only. Moreover, many of these combinations display multi-stability. >>️

Joao U.F. Lizarraga, Marcus A.M. de Aguiar. Sakaguchi Swarmalators. arXiv: 2305.08615v1 [nlin.PS]. May 15, 2023. 

https://arxiv.org/abs/2305.08615

Also:  'swarm', 'turbulence', 'noise', 'particle' in: https://www.inkgmr.net/kwrds.html

Keywords: gst, swarm, turbulence, noise, particle

# gst: intricate transitions in elastoactive structures.

<< The interplay between activity and elasticity often found in active and living systems triggers a plethora of autonomous behaviors ranging from self-assembly and collective motion to actuation. Among these, spontaneous self-oscillations of mechanical structures is perhaps the simplest and most widespread type of nonequilibrium phenomenon. >>️

<< Here, (AA) introduce a centimeter-sized model system for one-dimensional elastoactive structures. >>️

<< such structures exhibit flagellar motion when pinned at one end, self-snapping when pinned at two ends, and synchronization when coupled together with a sufficiently stiff link. (..) these transitions can be described quantitatively by simple models of coupled pendula with follower forces. >>️

Ellen Zheng, Martin Brandenbourger, et al. Self-Oscillation and Synchronization Transitions in Elastoactive Structures. Phys. Rev. Lett. 130, 178202. April 25, 2023. 

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.130.178202

Also:  transition, particle, self-assembly, elastic, pendulum in https://www.inkgmr.net/kwrds.html

Keywords: gst, transition, particle, self-assembly, elastic, pendulum

# gst: emergent organization and polarization due to active fluctuations.

AA << introduce and study a model of active Brownian motion with multiplicative noise describing fluctuations in the self-propulsion or activity. (They) find that the standard picture of density accumulation in slow regions is qualitatively modified by active fluctuations, as stationary density profiles are generally not determined only by the mean self-propulsion speed landscape. As a result, activity gradients generically correlate the particle self-propulsion speed and orientation, leading to emergent polarization at interfaces pointing either towards dense or dilute regions depending on the amount of noise in the system.  >>

️

Benoit Mahault, Prakhar Godara, Ramin Golestanian. Emergent organization and polarization due to active fluctuations. Phys. Rev. Research 5, L022012. April 12, 2023. 

https://journals.aps.org/prresearch/abstract/10.1103/PhysRevResearch.5.L022012

Also: 'particle', 'fluctuations', 'noise', 'self-assembly' in https://www.inkgmr.net/kwrds.html

Keywords: gst, particle, organization, polarization, fluctuations, noise, self-propulsion, self-assembly 

# gst: two steady collective states in swarmalators with delayed interactions

AA << investigate the effects of delayed interactions in a population of "swarmalators", generalizations of phase oscillators that both synchronize in time and swarm through space. >>

AA << discover two steady collective states: a state in which swarmalators are essentially motionless in a disk arranged in a pseudo-crystalline order, and a boiling state in which the swarmalators again form a disk, but now the swarmalators near the boundary perform boiling-like convective motions. >>️

Nicholas Blum, Andre Li, et al. Swarmalators with delayed interactions. arXiv: 2210.11417v1 [nlin.AO]. Oct 20, 2022. https://arxiv.org/abs/2210.11417

Also

keyword 'swarm' in FonT

https://flashontrack.blogspot.com/search?q=swarm

keyword 'particle' | 'quasiparticle' in FonT

https://flashontrack.blogspot.com/search?q=particle

https://flashontrack.blogspot.com/search?q=quasiparticle

keyword 'particelle' in Notes

(quasi-stochastic poetry)

https://inkpi.blogspot.com/search?q=particelle

Keywords: gst, particle, swarm