Collective dynamics in entangled worm and robot blobs

Living systems at all scales aggregate in large numbers for a variety of functions including mating, predation, and survival. The majority of such systems consist of unconnected individuals that collectively flock, school or swarm. However some aggregations involve physically entangled individuals, which can confer emergent mechanofunctional material properties to the collective. Here we study in laboratory experiments and rationalize in theoretical and robotic models the dynamics of physically entangled and motile self-assemblies of centimeter long California blackworms (L. Variegatus). Thousands of individual worms form braids with their long, slender and flexible bodies to make a three-dimensional, soft and shape-shifting ‘blob’. The blob behaves as a living material capable of mitigating damage and assault from environmental stresses through dynamic shape transformations, including minimizing surface area for survival against desiccation and enabling transport (negative thermotaxis) from hazardous environments (like heat). We specifically focus on the locomotion of the blob to understand how an amorphous entangled ball of worms is able to break symmetry to move across a substrate. We hypothesize that the collective blob displays rudimentary differentiation of function across itself, which when combined with entanglement dynamics facilitates directed persistent blob locomotion. To test this, we develop robophysical blobs, which display emergent locomotion in the collective without sophisticated control or programming of any individual robot. The emergent dynamics of the living functional blob and robophysical model can inform the rational design of exciting new classes of adaptive mechanofunctional living materials and emergent swarm robotics.Significance StatementLiving organisms form collectives across all scales, from bacteria to whales, enabling biological functions not accessible by individuals alone. In a few small cases, the individuals are physically connected to each other, forming to a new class of entangled active matter systems with emergent mechanofunctionalities of the collective. Here, we describe the dynamics of macroscopic aquatic worms that braid their long, soft bodies to form large entangled worm blobs. We discover that the worm blob behaves as a living material to undergo dynamic shape transformations to reduce evaporation or break-symmetry and locomote to safety against thermal stresses. We show that the persistent blob locomotion emerges as a consequence of physical entanglement and functional differentiation of individuals based on spatial location within a blob. We validate these principles in robophysical swarming blobs, that pave the way for new classes of mechanofunctional active matter systems and collective emergent robotics.

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Interactions between the land snails Theba pisana and Cernuella virgata in the laboratory

Journal of Molluscan Studies ◽

10.1093/mollus/eyaa038 ◽

2020 ◽

Author(s):

Geoff H Baker

Keyword(s):

Laboratory Experiments ◽

Distribution Patterns ◽

Land Snails ◽

Snail Species ◽

Agricultural Pests ◽

Large Numbers ◽

Small Scales ◽

Novel Method ◽

Theba Pisana ◽

Inhibitory Components

ABSTRACT Two Mediterranean snails, Theba pisana and Cernuella virgata, are agricultural pests in southern Australia. The two species are rarely found together in large numbers in the field, at small scales (<1 m2). In laboratory experiments, the presence of T. pisana reduced the survival of C. virgata, but only when food (carrot + lettuce) was provided. When C. virgata was exposed to only the mucus trails and faeces of T. pisana, produced while feeding on lettuce, both the survival and activity of C. virgata were reduced. When carrot was substituted for lettuce, there was less effect. In addition, when C. virgata was exposed to T. pisana’s faeces only, derived from access to a mix of lettuce and carrot, there was no effect on C. virgata’s survival. The observed reductions in the survival of C. virgata were stronger in autumn (the breeding season for both snail species) compared with spring. Inhibitory components within the mucus trails of T. pisana may (1) help explain the observed distribution patterns of the two species at small scales in the field and (2) provide a novel method for control of pest populations of C. virgata, in some situations.

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Dispersal of the sugar-cane scale Aulacaspis tegalensis (Zhnt.) (Hem., Diaspididae) by air currents

Bulletin of Entomological Research ◽

10.1017/s0007485300047404 ◽

1972 ◽

Vol 61 (3) ◽

pp. 547-558 ◽

Cited By ~ 20

Author(s):

D. J. Greathead

Keyword(s):

Sugar Cane ◽

Laboratory Experiments ◽

Sticky Trap ◽

Research Station ◽

High Humidity ◽

Dispersal Mechanism ◽

Large Numbers ◽

Speed Up ◽

Trap Catches ◽

Aulacaspis Tegalensis

By means of sticky traps and a suction trap, it was demonstrated on a plot of sugar-cane at Kawanda Research Station, Uganda, that large numbers of crawlers of Aulacaspis tegalensis (Zhnt.) become airborne (up to 10/m3). The numbers increase with wind speed up to about 2·0 m/s and then remain constant, but are depressed by increasing humidity. In laboratory experiments, crawler survival was reduced by high temperatures (30°C) and low humidities (30% r.h.), but some individuals should survive the extreme conditions sometimes experienced if airborne from morning until evening. On hatching, crawlers move upwards and towards the light, but downwards in the dark; movement is inhibited by high humidity. These behaviour responses indicate hat the presence of crawlers in the air is not accidental but a dispersal mechanism. At Arusha Chini, an isolated sugar estate in Tanzania, sticky-trap catches downwind of a windbreak confirmed that airborne dispersal of crawlers is a major source of infestation. It is shown that air currents could have carried crawlers to Arusha Chini from a source on the Kenya coast, 260 km to the east.

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Multiple-Image Encryption Algorithm Based on the 3D Permutation Model and Chaotic System

Symmetry ◽

10.3390/sym10110660 ◽

2018 ◽

Vol 10 (11) ◽

pp. 660 ◽

Cited By ~ 5

Author(s):

Xiaoqiang Zhang ◽

Xuesong Wang

Keyword(s):

Image Encryption ◽

Chaotic System ◽

Three Dimensional ◽

Multiple Image ◽

External Mode ◽

Large Numbers ◽

Permutation Model ◽

Magic Cube ◽

Exclusive Or ◽

Image Encryption Algorithm

Large numbers of images are produced in many fields every day. The content security of digital images becomes an important issue for scientists and engineers. Inspired by the magic cube game, a three-dimensional (3D) permutation model is established to permute images, which includes three permutation modes, i.e., internal-row mode, internal-column mode, and external mode. To protect the image content on the Internet, a novel multiple-image encryption symmetric algorithm (block cipher) with the 3D permutation model and the chaotic system is proposed. First, the chaotic sequences and chaotic images are generated by chaotic systems. Second, the sender permutes the plain images by the 3D permutation model. Lastly, the sender performs the exclusive OR operation on permuted images. The simulation and algorithm comparisons display that the proposed algorithm possesses desirable encryption images, high security, and efficiency.

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Liquid water infiltration into a layered snowpack: evaluation of a 3-D water transport model with laboratory experiments

Hydrology and Earth System Sciences ◽

10.5194/hess-21-5503-2017 ◽

2017 ◽

Vol 21 (11) ◽

pp. 5503-5515 ◽

Cited By ~ 8

Author(s):

Hiroyuki Hirashima ◽

Francesco Avanzi ◽

Satoru Yamaguchi

Keyword(s):

Liquid Water ◽

Laboratory Experiments ◽

Preferential Flow ◽

Transport Model ◽

Three Dimensional ◽

Water Infiltration ◽

Flow Paths ◽

Preferential Flow Paths ◽

Capillary Barriers ◽

Wet Snow

Abstract. The heterogeneous movement of liquid water through the snowpack during precipitation and snowmelt leads to complex liquid water distributions that are important for avalanche and runoff forecasting. We reproduced the formation of capillary barriers and the development of preferential flow through snow using a three-dimensional water transport model, which was then validated using laboratory experiments of liquid water infiltration into layered, initially dry snow. Three-dimensional simulations assumed the same column shape and size, grain size, snow density, and water input rate as the laboratory experiments. Model evaluation focused on the timing of water movement, thickness of the upper layer affected by ponding, water content profiles and wet snow fraction. Simulation results showed that the model reconstructs relevant features of capillary barriers, including ponding in the upper layer, preferential infiltration far from the interface, and the timing of liquid water arrival at the snow base. In contrast, the area of preferential flow paths was usually underestimated and consequently the averaged water content in areas characterized by preferential flow paths was also underestimated. Improving the representation of preferential infiltration into initially dry snow is necessary to reproduce the transition from a dry-snow-dominant condition to a wet-snow-dominant one, especially in long-period simulations.

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Continuum Mechanics for Coordinating Massive Microrobot Swarms

Novel Design and Applications of Robotics Technologies - Advances in Computational Intelligence and Robotics ◽

10.4018/978-1-5225-5276-5.ch004 ◽

2018 ◽

pp. 96-133

Author(s):

Bruce J. MacLennan

Keyword(s):

Partial Differential Equations ◽

Continuum Mechanics ◽

Scale Up ◽

Three Dimensional ◽

Fiber Bundles ◽

Coordination Mechanisms ◽

Embryological Development ◽

Large Numbers ◽

Continuous Mass ◽

Neural Fiber

This chapter addresses the problem of coordinating the behavior of very large numbers of microrobots to assemble complex, hierarchically structured physical objects. The approach is patterned after morphogenetic processes during embryological development, in which masses of simple agents (cells) coordinate to produce complex three-dimensional structures. To ensure that the coordination mechanisms scale up to hundreds of thousands or millions of microrobots, the swarm is treated as a continuous mass using partial differential equations. A morphogenetic programming notation permits algorithms to be developed for coordinating dense masses of microrobots. The chapter presents algorithms and simulations for assembling segmented structures (artificial spines and legs) and for routing artificial neural fiber bundles. These algorithms scale over more than four orders of magnitude.

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The magnetorotational instability prefers three dimensions

Proceedings of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rspa.2019.0622 ◽

2020 ◽

Vol 476 (2233) ◽

pp. 20190622

Author(s):

Jeffrey S. Oishi ◽

Geoffrey M. Vasil ◽

Morgan Baxter ◽

Andrew Swan ◽

Keaton J. Burns ◽

...

Keyword(s):

Shear Rate ◽

Angular Velocity ◽

Laboratory Experiments ◽

Three Dimensional ◽

Linear Instability ◽

Three Dimensions ◽

Two Dimensional ◽

Magnetorotational Instability ◽

Dynamo Action ◽

Wide Range

The magnetorotational instability (MRI) occurs when a weak magnetic field destabilizes a rotating, electrically conducting fluid with inwardly increasing angular velocity. The MRI is essential to astrophysical disc theory where the shear is typically Keplerian. Internal shear layers in stars may also be MRI-unstable, and they take a wide range of profiles, including near-critical. We show that the fastest growing modes of an ideal magnetofluid are three-dimensional provided the shear rate, S , is near the two-dimensional onset value, S c . For a Keplerian shear, three-dimensional modes are unstable above S ≈ 0.10 S c , and dominate the two-dimensional modes until S ≈ 2.05 S c . These three-dimensional modes dominate for shear profiles relevant to stars and at magnetic Prandtl numbers relevant to liquid-metal laboratory experiments. Significant numbers of rapidly growing three-dimensional modes remainy well past 2.05 S c . These finding are significant in three ways. First, weakly nonlinear theory suggests that the MRI saturates by pushing the shear rate to its critical value. This can happen for systems, such as stars and laboratory experiments, that can rearrange their angular velocity profiles. Second, the non-normal character and large transient growth of MRI modes should be important whenever three-dimensionality exists. Finally, three-dimensional growth suggests direct dynamo action driven from the linear instability.

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Inclusion of landslide tsunamis generation into a depth integrated wave model

Natural Hazards and Earth System Science ◽

10.5194/nhess-10-2259-2010 ◽

2010 ◽

Vol 10 (11) ◽

pp. 2259-2268 ◽

Cited By ~ 9

Author(s):

C. Cecioni ◽

G. Bellotti

Keyword(s):

Field Equation ◽

Small Amplitude ◽

Laboratory Experiments ◽

Three Dimensional ◽

Wave Model ◽

Dispersive Equations ◽

Far Field ◽

Mild Slope Equation ◽

Calculation Results ◽

Propagation Of Waves

Abstract. A numerical model based on the mild slope equation, suitable to reproduce the propagation of small amplitude tsunamis in the far field, is extended to reproduce the generation and the propagation of waves generated by landslides. The wave generation is modeled through a forcing term included in the field equation, which reproduces the effects of the movement of a submerged landslide on the fluid. The measurements of three dimensional laboratory experiments, which simulate tsunamis generated by landslide sliding along the flank of a conical island, are compared with the theoretical calculation results. The present approach is also compared with the similar method of Tinti et al. (2006) used for the generation of these waves in depth integrated model, and the different behavior when using frequency-dispersive and non-dispersive equations is highlighted.

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Specific and Nonhomologous Isofunctional Enzymes of the Genetic Information Processing Pathways as Potential Therapeutical Targets for Tritryps

Enzyme Research ◽

10.4061/2011/543912 ◽

2011 ◽

Vol 2011 ◽

pp. 1-8 ◽

Cited By ~ 3

Author(s):

Monete Rajão Gomes ◽

Ana Carolina Ramos Guimarães ◽

Antonio Basílio de Miranda

Keyword(s):

Information Processing ◽

Genetic Information ◽

Drug Targets ◽

Leishmania Major ◽

Homo Sapiens ◽

Three Dimensional ◽

Large Numbers ◽

Public Data ◽

Processing Pathways ◽

Genetic Information Processing

Leishmania major, Trypanosoma brucei, and Trypanosoma cruzi (Tritryps) are unicellular protozoa that cause leishmaniasis, sleeping sickness and Chagas' disease, respectively. Most drugs against them were discovered through the screening of large numbers of compounds against whole parasites. Nonhomologous isofunctional enzymes (NISEs) may present good opportunities for the identification of new putative drug targets because, though sharing the same enzymatic activity, they possess different three-dimensional structures thus allowing the development of molecules against one or other isoform. From public data of the Tritryps' genomes, we reconstructed the Genetic Information Processing Pathways (GIPPs). We then used AnEnPi to look for the presence of these enzymes between Homo sapiens and Tritryps, as well as specific enzymes of the parasites. We identified three candidates (ECs 3.1.11.2 and 6.1.1.-) in these pathways that may be further studied as new therapeutic targets for drug development against these parasites.

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Surface Lunar Soil Excavation Simulation Based on Three-Dimensional Discrete Element Method

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.376.366 ◽

2013 ◽

Vol 376 ◽

pp. 366-370

Author(s):

Hui Gao ◽

Da Wei Zhang ◽

Bin Liu ◽

Long Chen Duan

Keyword(s):

Discrete Element Method ◽

Three Dimensional ◽

Lunar Soil ◽

Discrete Element ◽

Spherical Particles ◽

Lunar Exploration ◽

The Earth ◽

Large Numbers ◽

Soil Excavation ◽

Element Method

One of the important objectives of lunar exploration is to obtain the lunar soil samples. However, the sampling process is very different from that on the Earth due to special characteristics of the lunar soil and surface environment. In order to ensure that the lunar exploration and sampling are successful, large numbers of ground experiments and computer simulations must be taken. In this paper, the surface lunar soil excavation simulation is investigated by three-dimensional discrete element method (DEM). It is implemented based on the open source LIGGGHTS, which takes the lunar soil as spherical particles. The interaction between the excavation tool and lunar soil is demonstrated. The excavation force and torque have also been calculated in real time. Moreover, the comparison of the excavation in different environments between the Earth and Moon corresponding to their different gravity accelerations was done. This paper shows that three-dimensional discrete element method can be used for the surface lunar soil excavation simulation and can provide important reference results for actual operations.

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