scholarly journals Better tired than lost: Turtle ant trail networks favor coherence over short edges

2021 ◽  
Vol 17 (10) ◽  
pp. e1009523
Author(s):  
Arjun Chandrasekhar ◽  
James A. R. Marshall ◽  
Cortnea Austin ◽  
Saket Navlakha ◽  
Deborah M. Gordon
Keyword(s):  
Path Length ◽  
Natural Variation ◽  
Trail Pheromone ◽  
Fundamental Problem ◽  
Edge Length ◽  
Food Sources ◽  
Arboreal Ants ◽  
Average Edge Length ◽  
Ant Trail ◽  
Minimizing Path

Creating a routing backbone is a fundamental problem in both biology and engineering. The routing backbone of the trail networks of arboreal turtle ants (Cephalotes goniodontus) connects many nests and food sources using trail pheromone deposited by ants as they walk. Unlike species that forage on the ground, the trail networks of arboreal ants are constrained by the vegetation. We examined what objectives the trail networks meet by comparing the observed ant trail networks with networks of random, hypothetical trail networks in the same surrounding vegetation and with trails optimized for four objectives: minimizing path length, minimizing average edge length, minimizing number of nodes, and minimizing opportunities to get lost. The ants’ trails minimized path length by minimizing the number of nodes traversed rather than choosing short edges. In addition, the ants’ trails reduced the opportunity for ants to get lost at each node, favoring nodes with 3D configurations most likely to be reinforced by pheromone. Thus, rather than finding the shortest edges, turtle ant trail networks take advantage of natural variation in the environment to favor coherence, keeping the ants together on the trails.

scholarly journals Better tired than lost: turtle ant trail networks favor coherence over shortest paths

2019 ◽  
Author(s):  
Arjun Chandrasekhar ◽  
James A. R. Marshall ◽  
Cortnea Austin ◽  
Saket Navlakha ◽  
Deborah M. Gordon
Keyword(s):  
Shortest Path ◽  
Natural Variation ◽  
Trail Pheromone ◽  
Fundamental Problem ◽  
Shortest Paths ◽  
Food Sources ◽  
Arboreal Ants ◽  
Ant Trail

AbstractCreating a routing backbone is a fundamental problem in both biology and engineering. The routing backbone of arboreal turtle ants (Cephalotes goniodontus) connects many nests and food sources using trail pheromone deposited by ants as they walk. Unlike species that forage on the ground, the trail networks of arboreal ants are constrained by the vegetation. We examined what objectives turtle ant networks meet by comparing the observed ant trail networks with networks of random, hypothetical trails in the same surrounding vegetation and with trails optimized for each objective. The ants’ trails minimized the number of nodes traversed, reducing the opportunity for ants to get lost at each node, and favored nodes with 3D configurations most likely to be reinforced by pheromone, thus keeping the ants together on the same trail. Rather than finding the shortest path, turtle ant trail networks take advantage of natural variation in the environment to favor coherence, keeping the ants together on the trails.

Facile Synthesis of Cu2O Nanocubes in Triblock Copolymer Solutions

2007 ◽  
Vol 121-123 ◽  
pp. 275-278
Author(s):  
Jin Hua Jiang ◽  
Qiu Ming Gao
Keyword(s):  
Triblock Copolymer ◽  
Solar Spectrum ◽  
Blue Shift ◽  
Edge Length ◽  
Promising Candidate ◽  
Organic Species ◽  
Transmission Electron ◽  
Ft Ir ◽  
Average Edge Length

Cuprous oxide and related materials in nanosizes are of much interest and investigated extensively recently. It is reported here that cubic Cu2O nanocubes were synthesized successfully in aqueous solutions at room temperature in air condition. Copper (II) salts in water were reduced with ascorbate acid in air, using the nonionic pluronic amphiphilic triblock copolymer EO20PO70EO20 (P123) as the template-directing and protecting agent. The average edge length of the cubes varied from 50 to 100 nm. Transmission electron microscopy (TEM) has been used for the shape and structural characterization of the obtained Cu2O nanocubes. The UV-Vis spectra showed an obvious blue-shift (0.53 eV), compared to the band gap of the bulk Cu2O crystal, which makes it a promising candidate in solar energy conversion since this sample can make use of higher energy visible rays of solar spectrum. In the FT-IR spectra the peak of Cu-O bond for the Cu2O is clearly distinguished and several weak peaks of the C-H, C-C and C=O bonds for the organic species can also be detectable, implying a little P123 residua in the products. The effect of the triblock copolymer P123 on the growth of the Cu2O nanocubes is discussed.

scholarly journals A fast quadrature-based gravity model for the homogeneous polyhedron

2019 ◽  
Vol 492 (1) ◽  
pp. 420-430
Author(s):  
Jason M Pearl ◽  
Darren L Hitt
Keyword(s):  
Gravitational Field ◽  
Gravity Model ◽  
Approximate Model ◽  
Edge Length ◽  
Gravity Models ◽  
Surface Topology ◽  
Constant Density ◽  
Bulk Properties ◽  
Average Edge Length ◽  
Computationally Expensive

ABSTRACT To date several probes have been sent to explore the Solar system’s asteroids and comets. These bodies are often irregular in shape and to safely navigate probes in their vicinity accurate gravity models are required. For an arbitrarily shaped constant-density body, the gravitational field can be determined from the surface topology and bulk properties. This is achieved by replacing the body’s true geometry with a polyhedron that closely resembles it and for which analytic equations for the gravitational field exist. For some applications however, these equations are too computationally expensive and it can be beneficial to replace them with numerically amenable approximations. In this work, a numerical-quadrature-based model for the gravitational field of a polyhedron consisting of triangular facets is derived. The proposed approximate model is found to be faster than its analytic counterpart. The error of the approximation is found to be negligible for the potential and Laplacian calculations. The approximate model introduces singularities to the surface of the acceleration calculation degrading the solution at altitudes less than the average edge length of the polyhedron.

scholarly journals Ants Sense, and Follow, Trail Pheromones of Ant Community Members

Insects ◽  
2019 ◽  
Vol 10 (11) ◽  
pp. 383 ◽  
Author(s):  
Jaime M. Chalissery ◽  
Asim Renyard ◽  
Regine Gries ◽  
Danielle Hoefele ◽  
Santosh Kumar Alamsetti ◽  
...  
Keyword(s):  
Trail Pheromone ◽  
Food Sources ◽  
Lasius Niger ◽  
Trail Following ◽  
Harvester Ants ◽  
Community Members ◽  
Trail Pheromones ◽  
Ant Community ◽  
Carpenter Ants ◽  
Electroantennographic Detection

Ants deposit trail pheromones that guide nestmates to food sources. We tested the hypotheses that ant community members (Western carpenter ants, Camponotus modoc; black garden ants, Lasius niger; European fire ants, Myrmica rubra) (1) sense, and follow, each other’s trail pheromones, and (2) fail to recognize trail pheromones of allopatric ants (pavement ants, Tetramorium caespitum; desert harvester ants, Novomessor albisetosus; Argentine ants, Linepithema humilis). In gas chromatographic-electroantennographic detection analyses of a six-species synthetic trail pheromone blend (6-TPB), La. niger, Ca. modoc, and M. rubra sensed the trail pheromones of all community members and unexpectedly that of T. caespitum. Except for La. niger, all species did not recognize the trail pheromones of N. albisetosus and Li. humilis. In bioassays, La. niger workers followed the 6-TPB trail for longer distances than their own trail pheromone, indicating an additive effect of con- and hetero-specific pheromones on trail-following. Moreover, Ca. modoc workers followed the 6-TPB and their own trail pheromones for similar distances, indicating no adverse effects of heterospecific pheromones on trail-following. Our data show that ant community members eavesdrop on each other’s trail pheromones, and that multiple pheromones can be combined in a lure that guides multiple species of pest ants to lethal food baits.

On average edge length of minimum spanning trees

1999 ◽  
Vol 70 (5) ◽  
pp. 241-243
Author(s):  
Suman Kumar Nath ◽  
Rezaul Alam Chowdhury ◽  
M. Kaykobad
Keyword(s):  
Spanning Trees ◽  
Edge Length ◽  
Minimum Spanning Trees ◽  
Average Edge Length

Argentine Ant Trail Pheromone Disruption is Mediated by Trail Concentration

2011 ◽  
Vol 37 (10) ◽  
pp. 1143-1149 ◽  
Author(s):  
David Maxwell Suckling ◽  
Lloyd D. Stringer ◽  
Joshua E. Corn
Keyword(s):  
Trail Pheromone ◽  
Argentine Ant ◽  
Ant Trail

scholarly journals Dietary protein content affects evolution for body size, body fat and viability in Drosophila melanogaster

2010 ◽  
Vol 7 (2) ◽  
pp. 269-272 ◽  
Author(s):  
Torsten N. Kristensen ◽  
Johannes Overgaard ◽  
Volker Loeschcke ◽  
David Mayntz
Keyword(s):  
Drosophila Melanogaster ◽  
Protein Content ◽  
Dietary Protein ◽  
Experimental Evolution ◽  
Natural Variation ◽  
Food Sources ◽  
Standard Diet ◽  
Total Body Mass ◽  
Total Body ◽  
Protein Rich

The ability to use different food sources is likely to be under strong selection if organisms are faced with natural variation in macro-nutrient (protein, carbohydrate and lipid) availabilities. Here, we use experimental evolution to study how variable dietary protein content affects adult body composition and developmental success in Drosophila melanogaster . We reared flies on either a standard diet or a protein-enriched diet for 17 generations before testing them on both diet types. Flies from lines selected on protein-rich diet produced phenotypes with higher total body mass and relative lipid content when compared with those selected on a standard diet, irrespective of which of the two diets they were tested on. However, selection on protein-rich diet incurred a cost as flies reared on this diet had markedly lower developmental success in terms of egg-to-adult viability on both medium types, suggesting a possible trade-off between the traits investigated.

DISTANCE PRESERVING SUBTREES IN MINIMUM AVERAGE DISTANCE SPANNING TREES

2013 ◽  
Vol 05 (03) ◽  
pp. 1350010
Author(s):  
LAURENT LYAUDET ◽  
PAULIN MELATAGIA YONTA ◽  
MAURICE TCHUENTE ◽  
RENÉ NDOUNDAM
Keyword(s):  
Approximate Solution ◽  
Spanning Tree ◽  
Path Length ◽  
Spanning Trees ◽  
Undirected Graph ◽  
Average Distance ◽  
Edge Length ◽  
The Other ◽  
First Results ◽  
Positive Length

Given an undirected graph G = (V, E) with n vertices and a positive length w(e) on each edge e ∈ E, we consider Minimum Average Distance (MAD) spanning trees i.e., trees that minimize the path length summed over all pairs of vertices. One of the first results on this problem is due to Wong who showed in 1980 that a Distance Preserving (DP) spanning tree rooted at the median of G is a 2-approximate solution. On the other hand, Dankelmann has exhibited in 2000 a class of graphs where no MAD spanning tree is distance preserving from a vertex. We establish here a new relation between MAD and DP trees in the particular case where the lengths are integers. We show that in a MAD spanning tree of G, each subtree H′ = (V′, E′) consisting of a vertex [Formula: see text] and the union of branches of [Formula: see text] that are each of size less than or equal to [Formula: see text], where w+ is the maximum edge-length in G, is a distance preserving spanning tree of the subgraph of G induced by V′.

scholarly journals Ant Trail Pheromone Biosynthesis Is Triggered by a Neuropeptide Hormone

PLoS ONE ◽  
2012 ◽  
Vol 7 (11) ◽  
pp. e50400 ◽  
Author(s):  
Man-Yeon Choi ◽  
Robert K. Vander Meer
Keyword(s):  
Trail Pheromone ◽  
Pheromone Biosynthesis ◽  
Neuropeptide Hormone ◽  
Ant Trail
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