scholarly journals Anisotropic interaction and motion states of locusts in a hopper band

2021 ◽  
Author(s):  
Jasper Weinburd ◽  
Jacob Landsberg ◽  
Anna Kravtsova ◽  
Shanni Lam ◽  
Tarush Sharma ◽  
...  
Keyword(s):  
Collective Motion ◽  
Video Tracking ◽  
Low Density ◽  
Natural Setting ◽  
Trajectory Data ◽  
Novel Interactions ◽  
The Individual ◽  
Low Density Area ◽  
Australian Plague Locust ◽  
Automated Video Tracking

Swarming locusts present a quintessential example of animal collective motion. Juvenile locusts march and hop across the ground in coordinated groups called hopper bands. Composed of up to millions of insects, hopper bands exhibit coordinated motion and various collective structures. These groups are well-documented in the field, but the individual insects themselves are typically studied in much smaller groups in laboratory experiments. We present the first trajectory data that detail the movement of individual locusts within a hopper band in a natural setting. Using automated video tracking, we derive our data from footage of four distinct hopper bands of the Australian plague locust, Chortoicetes terminifera. We reconstruct nearly twenty-thousand individual trajectories composed of over 3.3 million locust positions. We classify these data into three motion states: stationary, walking, and hopping. Distributions of relative neighbor positions reveal anisotropies that depend on motion state. Stationary locusts have high-density areas distributed around them apparently at random. Walking locusts have a low-density area in front of them. Hopping locusts have low-density areas in front and behind them. Our results suggest novel interactions, namely that locusts change their motion to avoid colliding with neighbors in front of them.

Parasites in space and time: a novel method to assess and illustrate host-searching behaviour of trematode cercariae

Parasitology ◽  
2018 ◽  
Vol 145 (11) ◽  
pp. 1469-1474 ◽  
Author(s):  
Christian Selbach ◽  
Robert Poulin
Keyword(s):  
Life Histories ◽  
Parasite Community ◽  
Video Tracking ◽  
Trematode Species ◽  
Host Searching ◽  
Novel Method ◽  
The Individual ◽  
Individual Strategies ◽  
Host Parasite ◽  
Automated Video Tracking

AbstractThe transmission from one host to another constitutes a challenging obstacle for parasites and is a key determinant of their fitness. Due to their complex life histories involving several different hosts, the free-living dispersal stages (cercariae) of digenean trematodes show a huge diversity in morphology and behaviour. On a finer scale, we still have an extremely limited understanding of the inter- and intraspecific variation in transmission strategies of many trematode species. Here, we present a novel method to study the movement patterns of cercariae of four New Zealand trematode species (Coitocaecum parvum, Maritrema poulini, Apatemon sp. and Aporocotylid sp. I.) via automated video tracking. This approach allows to quantify parameters otherwise not measurable and clearly illustrates the individual strategies of parasites to search for their respective target hosts. Cercariae that seek out an evasive fish target hosts showed higher swimming speeds (acceleration and velocity) and travelled further distances, compared with species searching for high-density crustacean hosts. Automated video tracking provides a powerful tool for such detailed analyses of parasites’ host-searching strategies and can enhance our understanding of complex host–parasite interactions, ranging from parasite community structure to the transmission of potential disease agents.

Analysis of the Bath Motion in the MM-SQC Dynamics Using Unsupervised Machine Learning Dimensionality Reduction Approaches: Principal Component Analysis

2020 ◽  
Author(s):  
Jiawei Peng ◽  
Yu Xie ◽  
Deping Hu ◽  
Zhenggang Lan
Keyword(s):  
Machine Learning ◽  
Principal Component Analysis ◽  
Collective Motion ◽  
Principal Component ◽  
Component Analysis ◽  
Nonadiabatic Dynamics ◽  
Trajectory Data ◽  
Unsupervised Machine Learning ◽  
Physical Knowledge ◽  
Vibronic Couplings

The system-plus-bath model is an important tool to understand nonadiabatic dynamics for large molecular systems. The understanding of the collective motion of a huge number of bath modes is essential to reveal their key roles in the overall dynamics. We apply the principal component analysis (PCA) to investigate the bath motion based on the massive data generated from the MM-SQC (symmetrical quasi-classical dynamics method based on the Meyer-Miller mapping Hamiltonian) nonadiabatic dynamics of the excited-state energy transfer dynamics of Frenkel-exciton model. The PCA method clearly clarifies that two types of bath modes, which either display the strong vibronic couplings or have the frequencies close to electronic transition, are very important to the nonadiabatic dynamics. These observations are fully consistent with the physical insights. This conclusion is obtained purely based on the PCA understanding of the trajectory data, without the large involvement of pre-defined physical knowledge. The results show that the PCA approach, one of the simplest unsupervised machine learning methods, is very powerful to analyze the complicated nonadiabatic dynamics in condensed phase involving many degrees of freedom.

Mobility-as-a-Service: Simulation of Multi-Modal Operations in Low-Density Cities

2021 ◽  
pp. 036119812110398
Author(s):  
Mohamed El-Agroudy ◽  
Hatem Abou-Senna ◽  
Essam Radwan
Keyword(s):  
Performance Measures ◽  
Magic Bullet ◽  
Low Density ◽  
The Novel ◽  
Review Of The Literature ◽  
Modal Interactions ◽  
New Approach ◽  
Novel Interactions ◽  
Alternative Scenarios ◽  
Urban Characteristics

In the case of the low-density city, empirical evidence continuously demonstrates that transit investment is not a magic bullet. Desirable outcomes are not guaranteed and are often dependent on development density and other urban characteristics. Mobility-as-a-service (MaaS) presents a new approach: a digital platform providing access to multi-modal travel alternatives and totally comprehensive integrated trip-making, planning, and payment services. Review of the literature highlights shortcomings in traditional transportation planning by examining aspects of multi-modal planning such as adoption, parterships, operations, integration, capacity implications, and impact analyses. To enhance the practice of multi-modal planning, the following experiment evaluates various performance measures and inter-modal interactions on International Drive in Orlando, Florida, U.S., via D- and I-optimal experimental designs in a simulated MaaS network. Alternative scenarios are developed comparing varied modal shares across five travel modes: personal vehicles, transit, ridesourcing (or ride-hailing), micro-mobility, and walking. The modal effects are analyzed to highlight the strengths and weakness of each mode under a variety of congestion conditions. While transit enjoys the lowest impact per person, ridesourcing demonstrates adverse effects across all measures. Based on the novel interactions of transit and ridesourcing with directional demand, strategies are outlined for optimizing ridesourcing-transit integration to reduce route travel time, queuing, and overall network delay. The performance impacts of curbside facilities are also discussed for improved multi-modal integration at the street level. These findings are applied to propose a framework for effective planning and implementation of mobility services in low-density cities, focused on operations, city-level connectivity, and curbside management.

USING TELEMEDICINE TECHNOLOGIES IN RADIOLOGY FOR LOW-DENSITY AREA

2017 ◽  
Vol 53 (1) ◽  
pp. 4-4
Author(s):  
T.S. Smal ◽  
◽  
V.D. Zavadovskaya ◽  
I.A. Deyev ◽  
◽  
...  
Keyword(s):  
Low Density ◽  
Density Area ◽  
Low Density Area

scholarly journals Mask R-CNN Refitting Strategy for Plant Counting and Sizing in UAV Imagery

2020 ◽  
Vol 12 (18) ◽  
pp. 3015 ◽  
Author(s):  
Mélissande Machefer ◽  
François Lemarchand ◽  
Virginie Bonnefond ◽  
Alasdair Hitchins ◽  
Panagiotis Sidiropoulos
Keyword(s):  
Deep Learning ◽  
Fine Tuning ◽  
Aerial Images ◽  
Individual Plant ◽  
Low Density ◽  
Tracking Accuracy ◽  
Potato Plants ◽  
The Individual ◽  
Segmentation Task ◽  
Vision Algorithm

This work introduces a method that combines remote sensing and deep learning into a framework that is tailored for accurate, reliable and efficient counting and sizing of plants in aerial images. The investigated task focuses on two low-density crops, potato and lettuce. This double objective of counting and sizing is achieved through the detection and segmentation of individual plants by fine-tuning an existing deep learning architecture called Mask R-CNN. This paper includes a thorough discussion on the optimal parametrisation to adapt the Mask R-CNN architecture to this novel task. As we examine the correlation of the Mask R-CNN performance to the annotation volume and granularity (coarse or refined) of remotely sensed images of plants, we conclude that transfer learning can be effectively used to reduce the required amount of labelled data. Indeed, a previously trained Mask R-CNN on a low-density crop can improve performances after training on new crops. Once trained for a given crop, the Mask R-CNN solution is shown to outperform a manually-tuned computer vision algorithm. Model performances are assessed using intuitive metrics such as Mean Average Precision (mAP) from Intersection over Union (IoU) of the masks for individual plant segmentation and Multiple Object Tracking Accuracy (MOTA) for detection. The presented model reaches an mAP of 0.418 for potato plants and 0.660 for lettuces for the individual plant segmentation task. In detection, we obtain a MOTA of 0.781 for potato plants and 0.918 for lettuces.

scholarly journals A Cellular Receptor of Human Rhinovirus Type 2, the Very-Low-Density Lipoprotein Receptor, Binds to Two Neighboring Proteins of the Viral Capsid

2003 ◽  
Vol 77 (15) ◽  
pp. 8504-8511 ◽  
Author(s):  
Emmanuelle Neumann ◽  
Rosita Moser ◽  
Luc Snyers ◽  
Dieter Blaas ◽  
Elizabeth A. Hewat
Keyword(s):  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Very Low Density Lipoprotein ◽  
Low Density ◽  
Lipoprotein Receptor ◽  
Low Density Lipoprotein Receptor ◽  
The North ◽  
Density Lipoprotein Receptor ◽  
The Individual ◽  
Viral Protein 1

ABSTRACT The very-low-density lipoprotein receptor (VLDL-R) is a receptor for the minor-group human rhinoviruses (HRVs). Only two of the eight binding repeats of the VLDL-R bind to HRV2, and their footprints describe an annulus on the dome at each fivefold axis. By studying the complex formed between a selection of soluble fragments of the VLDL-R and HRV2, we demonstrate that it is the second and third repeats that bind. We also show that artificial concatemers of the same repeat can bind to HRV2 with the same footprint as that for the native receptor. In a 16-Å-resolution cryoelectron microscopy map of HRV2 in complex with the VLDL-R, the individual repeats are defined. The third repeat is strongly bound to charged and polar residues of the HI and BC loops of viral protein 1 (VP1), while the second repeat is more weakly bound to the neighboring VP1. The footprint of the strongly bound third repeat extends down the north side of the canyon. Since the receptor molecule can bind to two adjacent copies of VP1, we suggest that the bound receptor “staples” the VP1s together and must be detached before release of the RNA can occur. When the receptor is bound to neighboring sites on HRV2, steric hindrance prevents binding of the second repeat.

scholarly journals A first-principle mechanism for particulate aggregation and self-assembly in stratified fluids

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Roberto Camassa ◽  
Daniel M. Harris ◽  
Robert Hunt ◽  
Zeliha Kilic ◽  
Richard M. McLaughlin
Keyword(s):  
Self Assembly ◽  
Large Scale ◽  
Collective Motion ◽  
Solute Diffusion ◽  
Many Body ◽  
Complex Interplay ◽  
Fluid Systems ◽  
The Individual ◽  
Many Particles ◽  
Fundamental Mechanism

AbstractAn extremely broad and important class of phenomena in nature involves the settling and aggregation of matter under gravitation in fluid systems. Here, we observe and model mathematically an unexpected fundamental mechanism by which particles suspended within stratification may self-assemble and form large aggregates without adhesion. This phenomenon arises through a complex interplay involving solute diffusion, impermeable boundaries, and aggregate geometry, which produces toroidal flows. We show that these flows yield attractive horizontal forces between particles at the same heights. We observe that many particles demonstrate a collective motion revealing a system which appears to solve jigsaw-like puzzles on its way to organizing into a large-scale disc-like shape, with the effective force increasing as the collective disc radius grows. Control experiments isolate the individual dynamics, which are quantitatively predicted by simulations. Numerical force calculations with two spheres are used to build many-body simulations which capture observed features of self-assembly.

scholarly journals Conformity in the collective: differences in hunger affect individual and group behavior in a shoaling fish

2019 ◽  
Vol 30 (4) ◽  
pp. 968-974 ◽  
Author(s):  
Alexander D M Wilson ◽  
Alicia L J Burns ◽  
Emanuele Crosato ◽  
Joseph Lizier ◽  
Mikhail Prokopenko ◽  
...  
Keyword(s):  
Collective Behavior ◽  
Nearest Neighbor ◽  
Collective Motion ◽  
Internal State ◽  
Group Behavior ◽  
Fundamental Interest ◽  
Individual Level ◽  
Group Members ◽  
The Individual ◽  
Nearest Neighbor Distances

Abstract Animal groups are often composed of individuals that vary according to behavioral, morphological, and internal state parameters. Understanding the importance of such individual-level heterogeneity to the establishment and maintenance of coherent group responses is of fundamental interest in collective behavior. We examined the influence of hunger on the individual and collective behavior of groups of shoaling fish, x-ray tetras (Pristella maxillaris). Fish were assigned to one of two nutritional states, satiated or hungry, and then allocated to 5 treatments that represented different ratios of satiated to hungry individuals (8 hungry, 8 satiated, 4:4 hungry:satiated, 2:6 hungry:satiated, 6:2 hungry:satiated). Our data show that groups with a greater proportion of hungry fish swam faster and exhibited greater nearest neighbor distances. Within groups, however, there was no difference in the swimming speeds of hungry versus well-fed fish, suggesting that group members conform and adapt their swimming speed according to the overall composition of the group. We also found significant differences in mean group transfer entropy, suggesting stronger patterns of information flow in groups comprising all, or a majority of, hungry individuals. In contrast, we did not observe differences in polarization, a measure of group alignment, within groups across treatments. Taken together these results demonstrate that the nutritional state of animals within social groups impacts both individual and group behavior, and that members of heterogenous groups can adapt their behavior to facilitate coherent collective motion.

Use of serum cholesterol/triglyceride ratio to discern for which individuals the Friedewald formula can be used confidently

1990 ◽  
Vol 36 (9) ◽  
pp. 1673-1675 ◽  
Author(s):  
M González Estrada ◽  
C R Rodríguez Ferrer ◽  
I R Astarloa ◽  
E M Lahera
Keyword(s):  
Total Cholesterol ◽  
Serum Cholesterol ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Very Low Density Lipoprotein ◽  
Low Density ◽  
Low Density Lipoprotein Cholesterol ◽  
Friedewald Formula ◽  
The Individual ◽  
Low Serum

Abstract The values of low-density lipoprotein cholesterol obtained according to the Friedewald formula (Clin Chem 1972; 18:499-502), or by the De Long transformation (J Am Med Assoc 1986;256:2372-7), were compared with the values obtained when the individual cholesterol/triglyceride ratio of very-low-density lipoprotein was used for estimating the contribution of this lipoprotein to the total cholesterol. We found that these formulas gave the greatest errors for individuals with a low serum cholesterol/triglyceride ratio. We propose criteria for deciding when the numerically calculated value of low-density cholesterol is appropriate, and when it is not.

Sign in / Sign up

Export Citation Format

Share Document