scholarly journals Sector search strategies for odor trail tracking

2021 ◽  
Author(s):  
Gautam Reddy ◽  
Boris I. Shraiman ◽  
Massimo Vergassola
Keyword(s):  
Close Contact ◽  
Sequential Optimization ◽  
Odor Trail ◽  
Optimization Framework ◽  
Behavioral Paradigm ◽  
Scent Trails ◽  
Loss Of Contact ◽  
Tracking Behavior ◽  
Geometric Elements ◽  
Unified Description

Terrestrial animals such as ants, mice and dogs often use surface-bound scent trails to establish navigation routes or to find food and mates, yet their tracking strategies are poorly understood. Tracking behavior features zig-zagging paths with animals often staying in close contact with the trail. Upon sustained loss of contact, animals execute a characteristic sequence of sweeping “casts” – wide oscillations with increasing amplitude. Here, we provide a unified description of trail-tracking behavior by introducing an optimization framework where animals search in the angular sector defined by their estimate of the trail’s heading and its uncertainty.In silicoexperiments using reinforcement learning based on this hypothesis recapitulate experimentally observed tracking patterns. We show that search geometry imposes limits on the tracking speed, and quantify its dependence on trail statistics and memory of past contacts. By formulating trail-tracking as a Bellman-type sequential optimization problem, we quantify the basic geometric elements of optimal sector search strategy, effectively explaining why and when casting is necessary. We propose a set of experiments to infer how tracking animals acquire, integrate and respond to past information on the tracked trail. More generally, we define navigational strategies relevant for animals and bio-mimetic robots, and formulate trail-tracking as a novel behavioral paradigm for learning, memory and planning.

scholarly journals Sector search strategies for odor trail tracking

2022 ◽  
Vol 119 (1) ◽  
pp. e2107431118
Author(s):  
Gautam Reddy ◽  
Boris I. Shraiman ◽  
Massimo Vergassola
Keyword(s):  
Polymer Physics ◽  
Sequential Optimization ◽  
Odor Trail ◽  
Learning Agents ◽  
Search Patterns ◽  
Behavioral Paradigm ◽  
Scent Trails ◽  
Loss Of Contact ◽  
Tracking Behavior ◽  
Geometric Elements

Ants, mice, and dogs often use surface-bound scent trails to establish navigation routes or to find food and mates, yet their tracking strategies remain poorly understood. Chemotaxis-based strategies cannot explain casting, a characteristic sequence of wide oscillations with increasing amplitude performed upon sustained loss of contact with the trail. We propose that tracking animals have an intrinsic, geometric notion of continuity, allowing them to exploit past contacts with the trail to form an estimate of where it is headed. This estimate and its uncertainty form an angular sector, and the emergent search patterns resemble a “sector search.” Reinforcement learning agents trained to execute a sector search recapitulate the various phases of experimentally observed tracking behavior. We use ideas from polymer physics to formulate a statistical description of trails and show that search geometry imposes basic limits on how quickly animals can track trails. By formulating trail tracking as a Bellman-type sequential optimization problem, we quantify the geometric elements of optimal sector search strategy, effectively explaining why and when casting is necessary. We propose a set of experiments to infer how tracking animals acquire, integrate, and respond to past information on the tracked trail. More generally, we define navigational strategies relevant for animals and biomimetic robots and formulate trail tracking as a behavioral paradigm for learning, memory, and planning.

scholarly journals Mice follow odor trails using stereo olfactory cues and rapid sniff to sniff comparisons

2018 ◽  
Author(s):  
Peter W Jones ◽  
Nathan N Urban
Keyword(s):  
Neural Substrates ◽  
Olfactory Cues ◽  
Odor Trail ◽  
Odor Concentration ◽  
Trail Use ◽  
Brain Circuits ◽  
Behavioral Paradigm ◽  
The Brain ◽  
Localization Behavior ◽  
Behavioral Monitoring

AbstractAnimals use the distribution of chemicals in their environment to guide behaviors essential for life, including finding food and mates, and avoiding predators. The presence of this general class of behavior is extremely widespread, even though the olfactory sensory apparatus and strategies used may vary between animals. The strategies and cues used by mammals to localize and track odor sources have recently become of interest to neuroscientists, but are still poorly understand. In order to study how mice localize odors, we trained mice to perform a trail following task using a novel behavioral paradigm and behavioral monitoring setup. We find that mice, in order to follow an odor trail, use both sniff by sniff odor concentration comparisons and internares comparisons to guide their behavior. Furthermore, they employ olfactory information to guide adaptive behaviors with remarkably short latencies of approximately 80ms. This study and its findings establish a rich, quantifiable olfactory localization behavior in mice that is amenable to physiological investigations and motivates investigation into the neural substrates of the identified olfactory cues.SignificanceMany animals, like rodents, rely heavily on their sense smell to guide them as they navigate their environment, to find food and mates and to avoid predators. Yet, in mammals, this function of the olfactory system is much less well studied than odor identification. We created a behavioral task where mice had to follow odor trails in order to efficiently find food and then tracked their movements around those trails. We found that they respond to sniff-by-sniff changes in odor intensity, using those changes to guide movements in less than one tenth of a second and also confirm that they use stereo cues to guide behavior. These results lay the groundwork for determining the brain circuits underlying olfactory navigation.

Estimating Dynamics On-the-Fly Using Monocular Video

2011 ◽  
Author(s):  
Priyanshu Agarwal ◽  
Suren Kumar ◽  
Jason J. Corso ◽  
Venkat Krovi
Keyword(s):  
Physical System ◽  
Sequential Optimization ◽  
Physical Parameters ◽  
Double Pendulum ◽  
Equivalent System ◽  
Pendulum System ◽  
System Parameters ◽  
Optimization Framework ◽  
Video Images ◽  
Monocular Image

We present an optimization framework to help estimate on-the-fly both the motion and physical parameters of an articulated multibody system using uncalibrated monocular image sequences. The algorithm takes video images of a physical system as input and estimates the motion together with the physical system parameters, given only the underlying articulated model topology. A valid initial pose of the system is found using a sequential optimization framework and used to bootstrap the successive pose estimation as well as estimation of physical system parameters (kinematic/geometric lengths as well as mass, inertia, damping coefficients). We also address the issue of robustly estimating a dynamically-equivalent system using partial state information (solely from noisy visual observations) and without explicit inertial parameter information. This framework results in a robust dynamically-equivalent system with good predictive capabilities when tested on a double pendulum system.

Ultrastructure of Liver in Lactosyl Ceramidosis

1971 ◽  
Vol 29 ◽  
pp. 312-313
Author(s):  
Z. Hruban ◽  
J. R. Esterly ◽  
G. Dawson ◽  
A. O. Stein
Keyword(s):  
Connective Tissue ◽  
Liver Biopsy ◽  
Osmium Tetroxide ◽  
Close Contact ◽  
Multivesicular Bodies ◽  
Bile Canaliculi ◽  
Dense Bodies ◽  
Marginal Plates ◽  
Membranous Material ◽  
Perichromatin Granules

Samples of a surgical liver biopsy from a patient with lactosyl ceramidosis were fixed in paraformaldehyde and postfixed in osmium tetroxide. Hepatocytes (Figs. 1, 2) contained 0.4 to 2.1 μ inclusions (LCI) limited by a single membrane containing lucid matrix and short segments of curved, lamellated and circular membranous material (Fig. 3). Numerous LCI in large connective tissue cells were up to 11 μ in diameter (Fig. 2). Heterogeneous dense bodies (“lysosomes”) were few and irregularly distributed. Rough cisternae were dilated and contained smooth vesicles and surface invaginations. Close contact with mitochondria was rare. Stacks were small and rare. Vesicular rough reticulum and glycogen rosettes were abundant. Smooth vesicular reticulum was moderately abundant. Mitochondria were round with few cristae and rare matrical granules. Golgi complex was seen rarely (Fig. 1). Microbodies with marginal plates were usual. Multivesicular bodies were very rare. Neutral lipid was rare. Nucleoli were small and perichromatin granules were large. Small bile canaliculi had few microvilli (Fig. 1).

Use of the Magnetostatic Analogue In Electromagnetic Lens Engineering

1970 ◽  
Vol 28 ◽  
pp. 360-361
Author(s):  
John W. Coleman
Keyword(s):  
Boundary Conditions ◽  
High Performance ◽  
Force Fields ◽  
Optical Design ◽  
Direct Conversion ◽  
Design Engineering ◽  
Design Data ◽  
Scalar Potentials ◽  
Geometric Elements ◽  
At Will

In the design engineering of high performance electromagnetic lenses, the direct conversion of electron optical design data into drawings for reliable hardware is oftentimes difficult, especially in terms of how to mount parts to each other, how to tolerance dimensions, and how to specify finishes. An answer to this is in the use of magnetostatic analytics, corresponding to boundary conditions for the optical design. With such models, the magnetostatic force on a test pole along the axis may be examined, and in this way one may obtain priority listings for holding dimensions, relieving stresses, etc..The development of magnetostatic models most easily proceeds from the derivation of scalar potentials of separate geometric elements. These potentials can then be conbined at will because of the superposition characteristic of conservative force fields.

Electron microscopy study of shock synthesis of silicides

1993 ◽  
Vol 51 ◽  
pp. 1162-1163
Author(s):  
Kenneth S. Vecchio
Keyword(s):  
Shock Wave ◽  
Plastic Deformation ◽  
Close Contact ◽  
Microscopy Study ◽  
High Energy ◽  
Electron Microscopy Study ◽  
Powder Materials ◽  
Porous Powder ◽  
Wave Effects ◽  
Wave Passage

Shock-induced reactions (or shock synthesis) have been studied since the 1960’s but are still poorly understood, partly due to the fact that the reaction kinetics are very fast making experimental analysis of the reaction difficult. Shock synthesis is closely related to combustion synthesis, and occurs in the same systems that undergo exothermic gasless combustion reactions. The thermite reaction (Fe2O3 + 2Al -> 2Fe + Al2O3) is prototypical of this class of reactions. The effects of shock-wave passage through porous (powder) materials are complex, because intense and non-uniform plastic deformation is coupled with the shock-wave effects. Thus, the particle interiors experience primarily the effects of shock waves, while the surfaces undergo intense plastic deformation which can often result in interfacial melting. Shock synthesis of compounds from powders is triggered by the extraordinarily high energy deposition rate at the surfaces of the powders, forcing them in close contact, activating them by introducing defects, and heating them close to or even above their melting temperatures.

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