scholarly journals Elements of a stochastic 3D prediction engine in larval zebrafish prey capture

2019 ◽  
Author(s):  
Andrew D Bolton ◽  
Martin Haesemeyer ◽  
Josua Jordi ◽  
Ulrich Schaechtle ◽  
Feras Saad ◽  
...  
Keyword(s):  
Computational Models ◽  
Prey Capture ◽  
Recursive Algorithm ◽  
Three Dimensional ◽  
Physical World ◽  
Three Dimensions ◽  
Hunting Behavior ◽  
Larval Zebrafish ◽  
Behavioral Rules ◽  
The Mean

ABSTRACTMany predatory animals rely on accurate sensory perception, predictive models, and precise pursuits to catch moving prey. Larval zebrafish intercept paramecia during their hunting behavior, but the precise trajectories of their prey have never been recorded in relation to fish movements in three dimensions.As a means of uncovering what a simple organism understands about its physical world, we have constructed a 3D-imaging setup to simultaneously record the behavior of larval zebrafish, as well as their moving prey, during hunting. We show that zebrafish robustly transform their 3D displacement and rotation according to the position of their prey while modulating both of these variables depending on prey velocity. This is true for both azimuth and altitude, but particulars of the hunting algorithm in the two planes are slightly different to accommodate an asymmetric strike zone. We show that the combination of position and velocity perception provides the fish with a preferred future positional estimate, indicating an ability to project trajectories forward in time. Using computational models, we show that this projection ability is critical for prey capture efficiency and success. Further, we demonstrate that fish use a graded stochasticity algorithm where the variance around the mean result of each swim scales with distance from the target. Notably, this strategy provides the animal with a considerable improvement over equivalent noise-free strategies.In sum, our quantitative and probabilistic modeling shows that zebrafish are equipped with a stochastic recursive algorithm that embodies an implicit predictive model of the world. This algorithm, built by a simple set of behavioral rules, allows the fish to optimize their hunting strategy in a naturalistic three-dimensional environment.

scholarly journals Asteroidal Motion at Commensurabilities Treated in Three Dimensions

1979 ◽  
Vol 81 ◽  
pp. 207-215 ◽  
Author(s):  
Joachim Schubart
Keyword(s):  
Three Dimensional ◽  
Three Dimensions ◽  
Main Subject ◽  
Long Period ◽  
Period Effects ◽  
Special Cases ◽  
The Mean ◽  
Work Done ◽  
Asteroidal Motion

This paper consists of a review about work done on three-dimensional motion at commensurabilities of either the mean motions, or of secular periods, and of a report on the author's recent results on some special cases. Real and fictitious asteroidal orbits and the corresponding long-period effects are the main subject of interest. At first, methods are listed.

Propagation of Low Frequency Elastic Disturbances in a Three-Dimensional Composite Material

1975 ◽  
Vol 42 (1) ◽  
pp. 159-164 ◽  
Author(s):  
W. Kohn
Keyword(s):  
Secular Equation ◽  
Displacement Vector ◽  
Three Dimensional ◽  
Low Frequency ◽  
Three Dimensions ◽  
Low Frequencies ◽  
One Dimensional ◽  
Coupled Partial Differential Equations ◽  
Constant Coefficients ◽  
The Mean

This paper is a generalization to three dimensions of an earlier study for one-dimensional composites. We show here that in the limit of low frequencies the displacement vector ui(r,t) can be written in the form ui (r,t) = (∂ij + vijl (r) ∂/∂xl + …) Uj (r,t). Here Uj (r,t) is a slowly varying vector function of r and t which describes the mean displacement of each cell of the composite. Its components satisfy a set of three coupled partial differential equations with constant coefficients. These coefficients are obtainable from the three-by-three secular equation which yields the low-lying normal mode frequencies, ω(k). Information about local strains is contained in the function vijl(r), which is characteristic of static deformations, and is discussed in detail. Among applications of this method is the structure of the head of a pulse propagating in an arbitrary direction.

Random sequential packing simulations in three dimensions for aligned cubes

1989 ◽  
Vol 26 (3) ◽  
pp. 664-670 ◽  
Author(s):  
Douglas W. Cooper
Keyword(s):  
Volume Fraction ◽  
Three Dimensional ◽  
Random Packing ◽  
Limit Problem ◽  
Three Dimensions ◽  
Standard Errors ◽  
Cube Root ◽  
Random Errors ◽  
Infinite Region ◽  
The Mean

This particular three-dimensional random packing limit problem is to determine the mean fraction of a cubic space that would be occupied by aligned, fixed, equalsize cubes, placed at random locations sequentially until no more can be added. No analytical solution has yet been found for this problem. Simulation results for a finite region and finite number of attempts were extrapolated to an infinite number of attempts (N →∞) in an infinite region by multiple linear regression, using volume fraction occupied (F) as a linear combination of the ratio of the length of the small cube sides (S) to the length of the cubic region side (L) and the cube root of the ratio of the region volume to the total volume of cubes tried, (L3/NS3)⅓. These results for random packing in a volume with penetrable walls can be adjusted with a multiplicative correction factor to give the results for impenetrable walls. A total of N = 107 attempts at placement were made for L/S = 20/1 and N = 14 × 106 attempts were made for L/S = 10/1. The results for volume fraction packed are correlated by F = 0.430(±0.008) + 0.966(±0.072)(S/L) – 0.236(±0.029)(L3/NS)⅓. The numbers in parentheses are twice the standard errors of estimate of the coefficients, indicating the 95% confidence intervals due to random errors. This value for the packing density limit, 0.430 ± 0.008, is slightly larger than that given by a conjecture by Palásti [10], 0.4178. Our value is consistent with that obtained by rather different simulation methods by Jodrey and Tory [8], 0.4227 ± 0.0006, and by Blaisdell and Solomon [2], 0.4262.

Vortical structures in the near wake of tabs with various geometries

2017 ◽  
Vol 825 ◽  
pp. 167-188 ◽  
Author(s):  
A. M. Hamed ◽  
A. Pagan-Vazquez ◽  
D. Khovalyg ◽  
Z. Zhang ◽  
L. P. Chamorro
Keyword(s):  
Large Scale ◽  
Three Dimensional ◽  
Three Dimensions ◽  
Incoming Flow ◽  
Mean Flow ◽  
Near Wake ◽  
Hairpin Vortices ◽  
Vortical Structures ◽  
The Mean ◽  
Hairpin Structures

The vortical structures and turbulence statistics in the near wake of rectangular, trapezoidal, triangular and ellipsoidal tabs were experimentally studied in a refractive-index-matching channel. The tabs share the same bulk dimensions, including a 17 mm height, a 28 mm base width and a $24.5^{\circ }$ inclination angle. Measurements were performed at two Reynolds numbers based on the tab height, $Re_{h}\simeq 2000$ (laminar incoming flow) and 13 000 (turbulent incoming flow). Three-dimensional, three-component particle image velocimetry (PIV) was used to study the mean flow distribution and dominant large-scale vortices, while complementary high-spatial-resolution planar PIV measurements were used to quantify high-order statistics. Instantaneous three-dimensional fields revealed the coexistence of a coherent counter-rotating vortex pair (CVP) and hairpin structures. The CVP and hairpin vortices (the primary structures) exhibit distinctive characteristics and strength across $Re_{h}$ and tab geometries. The CVP is coherently present in the mean flow field and grows in strength over a significantly longer distance at the low $Re_{h}$ due to the lower turbulence levels and the delayed shedding of the hairpin vortices. These features at the low $Re_{h}$ are associated with the presence of Kelvin–Helmholtz instability that develops over three tab heights downstream of the trailing edge. Moreover, a secondary CVP with an opposite sense of rotation resides below the primary one for the four tabs at the low $Re_{h}$. The interaction between the hairpin structures and the primary CVP is experimentally measured in three dimensions and shows complex coexistence. Although the CVP undergoes deformation and splitting at times, it maintains its presence and leads to significant mean spanwise and wall-normal flows.

scholarly journals On heating of solar wind protons by the parametric decay of large-amplitude Alfvén waves

2018 ◽  
Vol 36 (6) ◽  
pp. 1647-1655 ◽  
Author(s):  
Horia Comişel ◽  
Yasuhiro Nariyuki ◽  
Yasuhito Narita ◽  
Uwe Motschmann
Keyword(s):  
Magnetic Field ◽  
Large Amplitude ◽  
Three Dimensional ◽  
Three Dimensions ◽  
Alfven Wave ◽  
Sound Waves ◽  
Parametric Decay ◽  
Left Handed ◽  
Propagating Waves ◽  
The Mean

Abstract. By three-dimensional hybrid simulations, proton heating is investigated starting from a monochromatic large-amplitude Alfvén wave with left-handed circular polarization launched along the mean magnetic field in a low-beta plasma. We find that the perpendicular scattering is efficient in three dimensions and the protons are heated by the obliquely propagating waves. The thermal core proton population is heated in three dimensions as well in the longitudinal and parallel directions by the field-aligned and obliquely propagating sound waves out of the parametric decay. The astrophysical context is discussed.

scholarly journals A method for deducing neck mobility in plesiosaurs, using the exceptionally preserved Nichollssaura borealis

2018 ◽  
Vol 5 (8) ◽  
pp. 172307 ◽  
Author(s):  
Ramon S. Nagesan ◽  
Donald M. Henderson ◽  
Jason S. Anderson
Keyword(s):  
Vertebral Column ◽  
Prey Capture ◽  
Cervical Vertebrae ◽  
Three Dimensional ◽  
3D Models ◽  
3D Modelling ◽  
Lateral Neck ◽  
Modern Analogue ◽  
The Mean ◽  
Neck Mobility

The elongate-necked aquatic plesiosaurs existed for 135 Myr during the Mesozoic. The function of this elongate neck is a point of debate. Using computed tomography and three-dimensional (3D) modelling, the range of motion (ROM) of the plesiosaur Nichollssaura borealis neck was assessed. To quantify the ROM, the intervertebral mobility was measured along the cervical vertebral column. This was done by manipulating the 3D models in the lateral and dorsoventral directions during two trials. The first assessed the mean intervertebral ROM between pairs of cervical vertebrae along the entire column, and the second assessed ROM with reduced intervertebral spaces. The results suggest that there may be preference for lateral neck movements in N. borealis , which could correspond to an ecological function related to prey capture. This study demonstrates that 3D modelling is an effective tool for assessing function morphology for structures where no good modern analogue exists.

Trophic dynamics of two sympatric species of riparian spider (Araneae: Tetragnathidae)

1995 ◽  
Vol 73 (8) ◽  
pp. 1545-1553 ◽  
Author(s):  
D. Dudley Williams ◽  
Laura G. Ambrose ◽  
Laura N. Browning
Keyword(s):  
Water Surface ◽  
Prey Capture ◽  
Sympatric Species ◽  
Three Dimensions ◽  
Trophic Dynamics ◽  
The West ◽  
Insect Emergence ◽  
Large Numbers ◽  
The Mean ◽  
Minimum Estimate

Four species of Tetragnatha were found along the banks of Duffin Creek, Ontario: T. versicolor Walckenaer, T. elongata Walckenaer, T. laboriosa Hentz, and T. straminea Emerton. However, only the first two species were common; together they represented 91% of all species of spiders observed. Highest densities of T. elongata occurred in July, a time when numbers of T. versicolor were at their lowest. Growth rates differed between the two species. Both species were more common (2–3 times) on the east bank of the river than on the west. The locations (in three dimensions) of individual spiders along the banks were similar for both species, although T. elongata frequented shrubs overhanging the river more than T. versicolor, which was found farther away from the water's edge. The mean number of prey caught by T elongata was significantly higher than that caught by T. versicolor. Webs caught most prey when located 2–4 m from the water's edge, both in annual vegetation (grass level to a height of about 0.5 m) and in tall shrubs (1.5–2 m). Large numbers of prey were caught also in webs spun in shrubs and tree branches that hung over the water surface at a height of 1–2 m. The number of prey caught was not related to web diameter. Maximum prey capture by T. elongata coincided with the time of maximum total insect emergence in the river. Although the insect taxa found in the webs reflected those that were emerging in greatest numbers, typically chironomids and mayflies, other commonly emerging taxa (e.g., caddisflies and stoneflies) were conspicuously absent. The minimum estimate of the proportion of total insect emergence from this river that is captured by these two spider species is 0.2%.

Random sequential packing simulations in three dimensions for aligned cubes

1989 ◽  
Vol 26 (03) ◽  
pp. 664-670 ◽  
Author(s):  
Douglas W. Cooper
Keyword(s):  
Volume Fraction ◽  
Three Dimensional ◽  
Random Packing ◽  
Limit Problem ◽  
Three Dimensions ◽  
Standard Errors ◽  
Cube Root ◽  
Random Errors ◽  
Infinite Region ◽  
The Mean

This particular three-dimensional random packing limit problem is to determine the mean fraction of a cubic space that would be occupied by aligned, fixed, equalsize cubes, placed at random locations sequentially until no more can be added. No analytical solution has yet been found for this problem. Simulation results for a finite region and finite number of attempts were extrapolated to an infinite number of attempts (N →∞) in an infinite region by multiple linear regression, using volume fraction occupied (F) as a linear combination of the ratio of the length of the small cube sides (S) to the length of the cubic region side (L) and the cube root of the ratio of the region volume to the total volume of cubes tried, (L 3/NS 3)⅓. These results for random packing in a volume with penetrable walls can be adjusted with a multiplicative correction factor to give the results for impenetrable walls. A total of N = 107 attempts at placement were made for L/S = 20/1 and N = 14 × 106 attempts were made for L/S = 10/1. The results for volume fraction packed are correlated by F = 0.430(±0.008) + 0.966(±0.072)(S/L) – 0.236(±0.029)(L 3/NS)⅓ . The numbers in parentheses are twice the standard errors of estimate of the coefficients, indicating the 95% confidence intervals due to random errors. This value for the packing density limit, 0.430 ± 0.008, is slightly larger than that given by a conjecture by Palásti [10], 0.4178. Our value is consistent with that obtained by rather different simulation methods by Jodrey and Tory [8], 0.4227 ± 0.0006, and by Blaisdell and Solomon [2], 0.4262.

scholarly journals Entanglement Area Law in Disordered Free Fermion Anderson Model in One, Two, and Three Dimensions

2015 ◽  
Vol 2015 ◽  
pp. 1-4 ◽  
Author(s):  
Mohammad Pouranvari ◽  
Yuhui Zhang ◽  
Kun Yang
Keyword(s):  
Free Path ◽  
Anderson Model ◽  
Entanglement Entropy ◽  
Three Dimensional ◽  
Localization Length ◽  
Mean Free Path ◽  
Three Dimensions ◽  
Free Fermion ◽  
The Mean ◽  
Area Law

We calculate numerically the entanglement entropy of free fermion ground states in one-, two-, and three-dimensional Anderson models and find that it obeys the area law as long as the linear size of the subsystem is sufficiently larger than the mean free path. This result holds in the metallic phase of the three-dimensional Anderson model, where the mean free path is finite although the localization length is infinite. Relation between the present results and earlier ones on area law violation in special one-dimensional models that support metallic phases is discussed.

convergent-beam diffraction from surfaces

1987 ◽  
Vol 45 ◽  
pp. 30-33
Author(s):  
J. A. Eades ◽  
A. E. Smith ◽  
D. F. Lynch
Keyword(s):  
Reciprocal Lattice ◽  
Three Dimensional ◽  
Grazing Incidence ◽  
Three Dimensions ◽  
Plane Figure ◽  
Transmission Electron ◽  
Convergent Beam ◽  
Beam Patterns ◽  
Beam Diffraction

It is quite simple (in the transmission electron microscope) to obtain convergent-beam patterns from the surface of a bulk crystal. The beam is focussed onto the surface at near grazing incidence (figure 1) and if the surface is flat the appropriate pattern is obtained in the diffraction plane (figure 2). Such patterns are potentially valuable for the characterization of surfaces just as normal convergent-beam patterns are valuable for the characterization of crystals.There are, however, several important ways in which reflection diffraction from surfaces differs from the more familiar electron diffraction in transmission.GeometryIn reflection diffraction, because of the surface, it is not possible to describe the specimen as periodic in three dimensions, nor is it possible to associate diffraction with a conventional three-dimensional reciprocal lattice.

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