scholarly journals Spatio-temporal reconstruction of emergent flash synchronization in firefly swarms via stereoscopic 360-degree cameras

2020 ◽  
Vol 17 (170) ◽  
pp. 20200179 ◽  
Author(s):  
Raphaël Sarfati ◽  
Julie C. Hayes ◽  
Élie Sarfati ◽  
Orit Peleg
Keyword(s):  
Natural Habitat ◽  
Three Dimensional ◽  
Strongly Correlated ◽  
The North ◽  
Long Range Interactions ◽  
Distinct Individual ◽  
Dimensional Reconstruction ◽  
Controlled Environments ◽  
Spatio Temporal ◽  
Set Up

During mating season, males of synchronous firefly species flash in unison within swarms of thousands of individuals. These strongly correlated collective displays have inspired numerous mathematical models to explain how global synchronous patterns emerge from local interactions. Yet, experimental data to validate these models remain sparse. To address this gap, we develop a method for three-dimensional tracking of firefly flashes, using a stereoscopic set-up of 360-degree cameras. We apply this method to record flashing displays of the North American synchronous species Photinus carolinus in its natural habitat as well as within controlled environments, and obtain the three-dimensional reconstruction of flash occurrences in the swarm. Our results show that even a small number of interacting males synchronize their flashes; however, periodic flash bursts only occur in groups larger than 15 males. Moreover, flash occurrences are correlated over several metres, indicating long-range interactions. While this suggests emergent collective behaviour and cooperation, we identify distinct individual trajectories that hint at additional competitive mechanisms. These reveal possible behavioural differentiation with early flashers being more mobile and flashing longer than late followers. Our experimental technique is inexpensive and easily implemented. It is extensible to tracking light communication in various firefly species and flight trajectories in other insect swarms.

scholarly journals Spatiotemporal reconstruction of emergent flash synchronization in firefly swarms via stereoscopic 360-degree cameras

2020 ◽  
Author(s):  
Raphaël Sarfati ◽  
Julie Hayes ◽  
Élie Sarfati ◽  
Orit Peleg
Keyword(s):  
Natural Habitat ◽  
Three Dimensional ◽  
Strongly Correlated ◽  
Mating Season ◽  
The North ◽  
Long Range Interactions ◽  
Photinus Carolinus ◽  
Distinct Individual ◽  
Controlled Environments ◽  
Competitive Mechanisms

During mating season, males of synchronous firefly species flash in unison within swarms of thousands of individuals. These strongly-correlated collective displays have inspired numerous mathematical models to explain how global synchronous patterns emerge from local interactions. Yet, experimental data to validate these models remains sparse. To address this gap, we develop a method for three-dimensional tracking of firefly flashes, using a stereoscopic setup of 360-degree cameras. We apply this method to record flashing displays of the North American synchronous species Photinus carolinus in its natural habitat as well as within controlled environments, and obtain the 3D reconstruction of flash occurrences in the swarm. Our results show that even a small number of interacting males synchronize their flashes; however, periodic flash bursts only occur in groups larger than 15 males. Moreover, flash occurrences are correlated over several meters, indicating long-range interactions. While this suggests emergent collective behaviour and cooperation, we identify distinct individual trajectories that hint at additional competitive mechanisms. These reveal possible behavioural differentiation with early flashers being more mobile and flashing longer than late followers. Our experimental technique is inexpensive and easily implemented. It is extensible to tracking light communication in various firefly species and flight trajectories in other insect swarms.

3-D CARDIAC MODELING: A COMPUTER VISION APPROACH IN SPATIO-TEMPORAL IMAGE SEQUENCES

1996 ◽  
Vol 04 (02) ◽  
pp. 181-197 ◽  
Author(s):  
J.L. COATRIEUX ◽  
C. TOUMOULIN ◽  
R. COLLOREC
Keyword(s):  
Computer Vision ◽  
Three Dimensional ◽  
Object Identification ◽  
Image Sequences ◽  
Low Contrast ◽  
Dimensional Reconstruction ◽  
Contrast Structures ◽  
Computer Vision Applications ◽  
Spatio Temporal ◽  
Active Research

A very active research was conducted on motion analysis. Most of the concepts, methods and assumptions are well established and lead to additional improvements in computer vision applications. Even in medicine where we have to deal with noisy data, low contrast structures and deformable objects, they bring new cues at all the processing stages. This paper emphasizes the specificities of this area and also the potential difficulties. A compilation of results is given aimed at the quantification of heart kinetics in Digital Subtraction Angiography (DSA). They illustrate the benefits of cooperative schemes such as motion based segmentation, moving object identification, three-dimensional reconstruction and interpretation.

Spatio-Temporal Evolution of a Spot Under the EDL Effect

2004 ◽  
Author(s):  
Sedat Tardu ◽  
Huan-Ruei Shiu
Keyword(s):  
Initial Perturbation ◽  
Three Dimensional ◽  
Streamwise Velocity ◽  
Bypass Transition ◽  
Linear Evolution ◽  
Transition Mechanism ◽  
Time Space ◽  
Critical Reynolds Numbers ◽  
Spatio Temporal ◽  
Set Up

The effect of the electric double layer (EDL) on the bypass transition mechanism in the linear evolution stage is explored through direct numerical simulations. An initial perturbation velocity field consisting of a pair of counterrotating vortices is introduced in Poiseuille and EDL flows and the time-space evolution of the perturbed field is analysed for short times at half the critical Reynolds numbers (3000 for Poiseuille and 150 for EDL). The wall normal and spanwise perturbation velocities development are both quantitatively and qualitatively similar in macro and micro flows. The streamwise velocity, which is initially zero and set up by the generation of the wall normal vorticity is twice larger under the EDL effect. Both flows develop inclined strong streamwise shear layers. Overall is the close similarity of the disturbance evolution showing that the three dimensional linear mechanism in EDL flow lead to the structures that are at least as strong as in Poiseuille flow.

Spontaneous generation of a swirling plume in a stratified ambient

2014 ◽  
Vol 761 ◽  
pp. 443-463 ◽  
Author(s):  
Francisco Marques ◽  
Juan M. Lopez
Keyword(s):  
Temporal Dynamics ◽  
Numerical Study ◽  
Three Dimensional ◽  
Low Frequency ◽  
Spontaneous Generation ◽  
Fixed Temperature ◽  
Very Low Frequency ◽  
External Perturbations ◽  
Spatio Temporal ◽  
Set Up

AbstractThe transition from laminar to complex spatio-temporal dynamics of plumes due to a localized buoyancy source is studied numerically. Several experiments have reported that this transition is sensitive to external perturbations. Therefore, a well-controlled set-up has been chosen for our numerical study, consisting of a localized heat source at the bottom of an enclosed cylinder whose sidewall is maintained at a fixed temperature which varies linearly up the wall. Restricting the dynamics to the axisymmetric subspace, the first instability is to a puffing state. However, for smaller Grashof numbers, the plume becomes unstable to three-dimensional perturbations and a swirling plume spontaneously appears. The next bifurcation, viewed in the rotating frame where the plume is stationary, also exhibits puffing and suggests a connection between the unstable axisymmetric puffing solution and the swirling plume. Further bifurcations result in quasi-periodic states with a very low-frequency modulation, and these eventually become spatio-temporally complex.

scholarly journals Quantitative evaluation of a single-distance phase-retrieval method applied on in-line phase-contrast images of a mouse lung

2014 ◽  
Vol 21 (4) ◽  
pp. 784-789 ◽  
Author(s):  
Sara Mohammadi ◽  
Emanuel Larsson ◽  
Frauke Alves ◽  
Simeone Dal Monego ◽  
Stefania Biffi ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Phase Contrast ◽  
Phase Retrieval ◽  
Three Dimensional ◽  
Image Features ◽  
Mouse Lung ◽  
Data Sets ◽  
Retrieval Method ◽  
Dimensional Reconstruction ◽  
Set Up

Propagation-based X-ray phase-contrast computed tomography (PBI) has already proven its potential in a great variety of soft-tissue-related applications including lung imaging. However, the strong edge enhancement, caused by the phase effects, often hampers image segmentation and therefore the quantitative analysis of data sets. Here, the benefits of applying single-distance phase retrieval prior to the three-dimensional reconstruction (PhR) are discussed and quantified compared with three-dimensional reconstructions of conventional PBI data sets in terms of contrast-to-noise ratio (CNR) and preservation of image features. The PhR data sets show more than a tenfold higher CNR and only minor blurring of the edges when compared with PBI in a predominately absorption-based set-up. Accordingly, phase retrieval increases the sensitivity and provides more functionality in computed tomography imaging.

scholarly journals Data Assimilation of Argos profiles in North-west Pacific Model

2016 ◽  
Author(s):  
Zhaoyi Wang ◽  
Andrea Storto ◽  
Nadia Pinardi ◽  
Guimei Liu ◽  
Hui Wang
Keyword(s):  
Data Assimilation ◽  
Three Dimensional ◽  
Background Error ◽  
West Pacific ◽  
North West ◽  
Background Estimation ◽  
In Situ Data ◽  
The North ◽  
Salinity Data ◽  
Set Up

Abstract. Based on a novel specification of the background error covariance applying to Argos profiles assimilation, an oceanographic three-dimensional variational (3DVAR) data assimilation scheme is set up in the Regional Oceanic Model system (ROMs). Temperature and salinity data extracted from Argos profiles in 2006 have been assimilated into the North-West Pacific Model (NWPM). The quality control is done by comparing background estimation with observations in 2006.Firstly, the assimilated results are compared with merged in-situ data, Sea Surface Temperature (SST) derived from satellite data and reanalysis salinity data. It is found that assimilation of Argos profiles can improve the model results of SST and salinity. Secondly, the Root Mean Square (RMS) difference between model and Argos profiles is analyzed. For the tropic Pacific, the range of RMS temperature (salinity) error are less than 0.83 ℃ (0.11 PSU), decreasing ~ 23.2 % (~ 18.8 %) by comparing with the experiments without data assimilation. For the sub-tropic Pacific Ocean, the RMS of temperature (salinity) is less than 1.43 ℃ (0.135 PSU) and it also shows a decreasing trend after assimilation. It's indicated that the 3DVAR method works well in ROMs and can be used for the operational forecasting systems.

Three-Dimensional Reconstruction Using Stereo Pairs from Serial Thick Sections

1977 ◽  
Vol 35 ◽  
pp. 562-563
Author(s):  
Robert Glaeser ◽  
Thomas Bauer ◽  
David Grano
Keyword(s):  
Three Dimensional ◽  
Dimensional Structure ◽  
Serial Sections ◽  
Thin Sections ◽  
3 Dimensional ◽  
Transmission Electron ◽  
Freeze Dried ◽  
Dimensional Reconstruction ◽  
Stereo Imagery ◽  
Whole Mounts

In transmission electron microscopy, the 3-dimensional structure of an object is usually obtained in one of two ways. For objects which can be included in one specimen, as for example with elements included in freeze- dried whole mounts and examined with a high voltage microscope, stereo pairs can be obtained which exhibit the 3-D structure of the element. For objects which can not be included in one specimen, the 3-D shape is obtained by reconstruction from serial sections. However, without stereo imagery, only detail which remains constant within the thickness of the section can be used in the reconstruction; consequently, the choice is between a low resolution reconstruction using a few thick sections and a better resolution reconstruction using many thin sections, generally a tedious chore. This paper describes an approach to 3-D reconstruction which uses stereo images of serial thick sections to reconstruct an object including detail which changes within the depth of an individual thick section.

3-D reconstruction of molecular shape from microcrystal thin sections

1983 ◽  
Vol 41 ◽  
pp. 748-749
Author(s):  
S. Cusack ◽  
J.-C. Jésior
Keyword(s):  
Three Dimensional ◽  
Molecular Shape ◽  
Biological Molecules ◽  
Fourier Space ◽  
Single Particles ◽  
Thin Sections ◽  
Standard Methods ◽  
X Ray ◽  
X Ray Crystallography ◽  
Dimensional Reconstruction

Three-dimensional reconstruction techniques using electron microscopy have been principally developed for application to 2-D arrays (i.e. monolayers) of biological molecules and symmetrical single particles (e.g. helical viruses). However many biological molecules that crystallise form multilayered microcrystals which are unsuitable for study by either the standard methods of 3-D reconstruction or, because of their size, by X-ray crystallography. The grid sectioning technique enables a number of different projections of such microcrystals to be obtained in well defined directions (e.g. parallel to crystal axes) and poses the problem of how best these projections can be used to reconstruct the packing and shape of the molecules forming the microcrystal.Given sufficient projections there may be enough information to do a crystallographic reconstruction in Fourier space. We however have considered the situation where only a limited number of projections are available, as for example in the case of catalase platelets where three orthogonal and two diagonal projections have been obtained (Fig. 1).

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