Bulletin of the American Physical Society
APS March Meeting 2019
Volume 64, Number 2
Monday–Friday, March 4–8, 2019; Boston, Massachusetts
Session B65: Physics of Behavior IIFocus
|
Hide Abstracts |
Sponsoring Units: DBIO Chair: Yuhai Tu, IBM T J Watson Res Ctr Room: BCEC 260 |
Monday, March 4, 2019 11:15AM - 11:51AM |
B65.00001: Collective mechanical adaptation of honeybee swarms Invited Speaker: Orit Peleg Honeybee swarms form large congested tree-hanging clusters made solely of bees attached to each other. How these structures are maintained under the influence of dynamic mechanical forcing is unknown. To address this, we created pendant clusters and subject them to dynamic loads of varying orientation, amplitude, frequency and duration1. We find that horizontally shaken clusters adapt by spreading out to form wider, flatter cones that recover their original shape when unloaded. Measuring the response of a cluster to an impulsive pendular excitation shows that flattened cones deform less and relax faster than the elongated ones. Particle-based simulations of a passive assemblage suggest a behavioural hypothesis: individual bees respond to local variations in strain by moving up the strain gradient, which is qualitatively consistent with our observations of individual bee movement during dynamic loading. Together, our findings highlight how a super-organismal structure responds to dynamic loading by actively changing its morphology to improve the collective stability of the cluster at the expense of increasing the average mechanical burden of an individual. |
Monday, March 4, 2019 11:51AM - 12:03PM |
B65.00002: Unsupervised Classification of Behavior for Open Field Mouse Recordings Ugne Klibaite, Jessica Verpeut, Mikhail Kislin, Samuel S Wang, Joshua Shaevitz Advances in computer vision and deep learning have made it possible to explore animal behavior at fine temporal and spatial scales. In particular, new advances in automated pose detection make it possible to track fine-scale movements in mice, a model system for the study of many aspects of neural function, from locomotion and coordination to complex neurodevelopmental disorders such as autism. We combine the use of a deep-learning-based approach called LEAP (LEAP Estimates Animal Pose), which produces estimates of joint coordinates, with unsupervised classification in order to discover distinct behavioral bouts in 72 wild-type mice in an open field arena over five subsequent days. We use the resulting behavioral phenotypes to explore the evolution of behavior in individuals over time, as well as identify behavioral differences between wild-type individuals and genetic models of neurodegenerative disease. These differences elucidate complex phenotypes that arise from neuropathology, and capture greater complexity with fewer experimental constraints than simpler high-throughput behavioral assays. |
Monday, March 4, 2019 12:03PM - 12:15PM |
B65.00003: Underwater Sound Localization: ICE and Helmholtz resonators J Leo Van Hemmen Internally coupled ears (ICE), where an interaural cavity of some shape acoustically couples the eardrums, is an anatomical trait present in more than half of the terrestrial vertebrates. The superposition of outside and internal pressure on the two eardrums results in internal time and level differences, which are keys to sound localization. Although ICE is primarily a low-frequency terrestrial adaptation, the African clawed frog Xenopus laevis is a fully aquatic species with a distinct air-filled connection between the ears. Unlike terrestrial animals with ICE, the Xenopus interaural cavity is also medially connected to the lungs. By modeling the inflated lungs as a Helmholtz resonator, we demonstrate their effect on improving hearing in a low-frequency regime, while simultaneously enhancing sound localization in a disjoint high-frequency regime, corresponding to the frequency range of male advertisement calls. In conjunction with its unique plate-like eardrums, we show how Xenopus uses its ICE-like interaural coupling to generate considerable internal level differences between eardrum vibrations and thus overcomes the challenges of underwater sound-localization. |
Monday, March 4, 2019 12:15PM - 12:27PM |
B65.00004: Modeling the hidden dynamics of Drosophila behavior with recurrent neural networks Katherine Overman, Itai Pinkoviezky, Gordon Berman
|
Monday, March 4, 2019 12:27PM - 12:39PM |
B65.00005: Investigating material properties of fish schools with dynamic light fields Aawaz Pokhrel, Pranav Kayastha, James Puckett
|
Monday, March 4, 2019 12:39PM - 12:51PM |
B65.00006: Noise Induced Bistability of Ants Foraging using Indirect Recruitment K. Michael Martini, Nigel David Goldenfeld Bistability is usually modeled using a double well potential and simple white noise. There is, however, an alternative mathematical description of bistability utilizing a simple harmonic potential and multiplicative noise. The noise is greatest at the bottom of the well and vanishes at the boundaries, such that dz/dt = -z + s sqrt(1-z2) η, where η is Gaussian noise, z is the bistable quantity and s controls the strength of the noise. Previous studies have shown that when ants directly recruit one another to forage from one of two food sources, the ants exhibit this type of bistability. At small population sizes, the ants will forage bistably from the different food sources, but as the population size is increased over a certain critical population size, they will start to forage from both food sources equally. We extend this model to include indirect recruitment of ants to a food source via a pheromone laid out by other ants. The critical population size of this extended model depends on the ratio of the rates of creation and evaporation of the pheromones. Here we map the phase diagram for the extended model both analytically and through computer simulation. This model makes robust predictions that can be experimentally tested. |
Monday, March 4, 2019 12:51PM - 1:03PM |
B65.00007: Decompositions of Behavioral Modulations and Run Shapes in Drosophila Larvae Joseph Shomar, Anggie Ferrer, Joshua Forer, Tom Zhang, Mason Klein With its small size and limited motor tool set, the Drosophila larva is a good system for studying how animals alter their behavior to reach optimal conditions. We aim to distinguish behavioral modulations caused by the physical effects of temperature from those due to sensory input and to decompose curved runs (bouts of forward crawling) into run-shape eigenvectors. |
Monday, March 4, 2019 1:03PM - 1:15PM |
B65.00008: Slingshot Spider: Ultrafast kinematics, biological function and physical models of an extreme arachnid Symone Alexander, Saad Bhamla The natural evolution of ultrafast motion in living systems has inspired physicists, biologists, and engineers to design biomimetic materials and fast-moving robots. In this work, we quantify kinematics of a tiny ‘slingshot spider’ native to the Peruvian Amazon Rainforest. This spider exploits a conical 3D web structure to slingshot itself at extreme speeds and achieve accelerations exceeding 600 m/s2, an order of magnitude faster than a cheetah (13 m/s2). To the best of our knowledge, this is the fastest movement by an arachnid ever recorded. In this talk, we will discuss how slingshot spiders achieve ultrafast motion, and share insight about the biological function of this extraordinary prey capture strategy. We reveal how the motion is actuated by a trigger mechanism that happens under a millionth of a second (0.8 μs). Lastly, we extract the underlying physics of this motion and the role of the 3D web in power amplification using simple physical models constructed from elastic rubber bands. The physical models further shed insight into built-in safety structures in the web that rapidly dissipate excess energy and protect the spider against the large stresses generated during this extreme motion. |
Monday, March 4, 2019 1:15PM - 1:27PM |
B65.00009: Testing a thermodynamic approach to collective animal behavior in laboratory fish schools Julia A Giannini, James Puckett Social animals including insects, fish, birds, and even humans exhibit self-organized collective behavior. Macroscopic properties arise not only from interactions between individuals, but also from environmental cues. Here, we present results from a series of experiments that utilize high speed footage of 2D schooling events, particle-tracking, and projected static and dynamic light fields to observe and control the behavior of negatively phototaxic laboratory fish schools (Hemigrammus bleheri). First, we use static light fields consisting of dark circular regions to produce visual stimuli that confine the schools to a range of areas. Next, we use dynamic light fields where the radius of the dark region shrinks linearly with time to compress the schools. Through measuring global quantities analogous to density, temperature, and pressure in statistical mechanics, we find that the temperature-like parameter depends on the speed of the compression. We discuss the implications of our results on current models. |
Monday, March 4, 2019 1:27PM - 1:39PM |
B65.00010: Mechanics of Snow-diving Animals Leena Park, Emmanuel Virot, Sunghwan Jung Some fox species plunge-dive to catch prey (e.g. rodents) underneath a pile of snow. This hunting behavior is known as “mousing.” In this behavior, the diving speed can range between 2 and 4 m/s. Here, we investigate how foxes dive into snow without alerting prey. An important factor to consider in this mousing process is the impact on snow. Snow is a compressible fluid consisting of 1~10% ice and the rest of air. When a tapered object (in this case, a fox’s head) compresses or dives into the snow, the pressure/information front does not propagate fast enough for the prey to detect and escape. Animals that portray this mousing behavior, such has red foxes, arctic foxes, and even servals and other feline species, all generally share a slim, narrow facial structure. In this study, 3D printed fox heads and similar funnel-shaped objects are dropped into a pile of snow to understand the propagation of the pressure in snow and the drag on the object. |
Monday, March 4, 2019 1:39PM - 1:51PM |
B65.00011: How to jump without spinning Madhusudhan Venkadesan, Alexander Lee, Eric Chan The remarkable displays of jumping in animals like frogs have inspired many studies on how their muscles generate power. However, in their natural habitats, these animals typically push off against muddy and unpredictably compliant terrains that induce the feet to apply unequal forces on the ground. This may result in substantial angular momentum at take-off, and have dire consequences such as the animal's mouth pointing away from an intended prey, or landing in ways that prevent escaping a predator. We investigated whether morphological features of jumping animals may alleviate this critical problem and help them to jump without spinning. Our analyses and experiments with a brainless passive mechanical jumper focus on the dynamics within the frontal plane as it pushes off unequally using two legs. We find that a flexible pelvis is sufficient to reduce the angular momentum due to unequal leg forces by several orders of magnitude in both our experiments and mathematical analyses. A flexible pelvis acts like a whiffletree mechanism that can balance loads between the legs. Our scaling analyses of these jumpers suggest passive mechanical designs for robotic jumpers and point to the critical role of pelvis morphology in jumping animals for stability. |
Monday, March 4, 2019 1:51PM - 2:03PM |
B65.00012: Geckos reconfigure control modules to self-right on diverse substrates Benjamin McInroe, Thomas Libby, Daniel E Koditschek, Robert Full Animals synergistically employ multiple appendages and body segments to perform behaviors. We hypothesize that these controllable components can be represented by sets of simple models (templates), recruited in series or parallel to provide multiple strategies for executing a maneuver. As the physics of substrate-body interaction changes, these control modules may be reconfigured for new functions, enabling task completion in new environments. To further define our conjecture, we measured terrestrial self-righting in geckos. On flat, rigid surfaces, geckos self-righted with average righting times of 0.22 ± 0.03 s using dynamic motions including body torsion and tail-ground contact. When placed on a partially excavated surface where the tail could not make ground contact, average righting time increased by 40%. However, righting time decreased to 0.19 ± 0.02 s if the geckos used a new strategy, swinging the tail in a way similar to inertial air righting. Body-level behavior was invariant to the dichotomy in tail control. From our experiments, we begin to develop composable templates for terrestrial righting. Our results suggest that geckos employ the tail as a multifunctional control module in parallel with a body torsion template to increase robustness to challenging substrates. |
Monday, March 4, 2019 2:03PM - 2:15PM |
B65.00013: Tuning impulsive mechanisms to their environment Sathvik Divi, Mark Ilton, Xiaotian Ma, Sarah Bergbreiter Organisms like fleas and froghoppers achieve fast repeatable motions due to the presence of highly tuned impulsive mechanisms; a motor slowly loads a spring, and this stored energy is quickly released by a latch. In this work, we explore how the latch and spring parameters are tuned to their environments to maximize performance. An analytical model is constructed to include both impulsive system parameters (e.g., mass, spring, latch) as well as the compliance and inertia of the environment. Simulations are then performed across the design space to understand the tuning relationship between the latch, spring and substrate (environment) parameters. These results are validated experimentally using an 8-gram robot for which latch and spring parameters can be changed. This robot is then tested on multiple compliant substrates. Results demonstrate that the latch and spring parameters can be tuned to their environment to maximize take-off velocity. Certain combinations of latch/spring/environment parameters result in recovery of energy from the compliant substrate thereby resulting in higher performance, and ultimately efficient, fast, and repeatable motions. |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700