Nearest-neighbour distance, rather than group size, affects vigilance in urban flocks of preening Black-headed Gulls Chroicocephalus ridibundus

Bird Study ◽  
2021 ◽  
pp. 1-9
Author(s):  
Ivana Novčić ◽  
Zoran Vidović
Keyword(s):  
Group Size ◽  
Nearest Neighbour ◽  
Neighbour Distance

ELASTIC PROPERTIES OF STRAINED FCC AND HCP IRON

1993 ◽  
Vol 07 (01n03) ◽  
pp. 207-211
Author(s):  
T. KRAFT ◽  
M. METHFESSEL ◽  
M. VAN SCHILFGAARDE ◽  
M. SCHEFFLER
Keyword(s):  
Energy Cost ◽  
Interplanar Distance ◽  
Orbital Method ◽  
Full Potential ◽  
Local Spin Density Approximation ◽  
Nearest Neighbour ◽  
Density Approximation ◽  
Neighbour Distance ◽  
Large Lattice ◽  
Fcc Phase

Using the full-potential linear muffin-tin orbital method within the local spin-density approximation we analyse the influence of the nearest neighbour distance on fcc(111) or hcp(0001) iron layers. The LDA-LSDA error in describing ferromagnetic phases is determined to be at least 15 mRy/atom. As a consequence of this error, our calculations favour paramagnetic ground states. In this sense, the reported results have some model character. However, our analysis of the elastic energy cost under distortions should hold for transition metals in general. Allowing relaxations of the interplanar distance the fcc phase can become energetically favourable over the hcp phase at large lattice mismatches. The main reason for this behaviour is the enhanced stiffness of the hcp interplanar bonds due to the shortening of the axial c/a ratio.

Simulation of Dynamics of Solid-Liquid Transition

1995 ◽  
Vol 407 ◽  
Author(s):  
Y. Kogure ◽  
H. Masuyama ◽  
M. Doyama
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Nearest Neighbour ◽  
Neighbour Distance ◽  
Liquid Transition ◽  
Dynamics Simulations ◽  
Solid Liquid ◽  
Copper Crystals

ABSTRACTMolecular dynamics simulations on the solid-liquid transition of copper crystals have been performed. The configulation and the motion of atoms are monitored by RDF. It is seen that the height of the first peak in the RDF, which located at the nearest neighbour distance, decreased drastically as the temperature is increased.

Struktur von Schmelzen aus dem System Wismut-Antimon mittels Neutronenbeugung

1976 ◽  
Vol 31 (1) ◽  
pp. 90-101 ◽  
Author(s):  
Peter Lamparter ◽  
Siegfried Steeb ◽  
Walter Knoll
Keyword(s):  
Neutron Diffraction ◽  
Coordination Number ◽  
Covalent Binding ◽  
The Other ◽  
Nearest Neighbour ◽  
Neighbour Distance ◽  
The Mean ◽  
The One ◽  
Subsidiary Maxima ◽  
Versus Concentration

Neutron diffraction work (λ = 0.695 Å) was done with molten Bi-Sb-alloys in the temperature range between 550 and 750 °C. Furthermore molten Bi was investigated at 300 °C. The interference functions show subsidiary maxima especially for alloys with higher Sb-concentrations. Evaluation yields, that the melts contain two different kinds of structure:a) The one kind shows coordination number 9 and a statistical distribution of the atoms of two components. This kind is more inetal-like.b) The other kind shows coordination number 3, consists of non-centered tetrahedra with smaller nearest neighbour distance. It shows covalent binding.In molten Sb the nearest neighbour distance amounts up to 3.16 - 3.19 Å for theo ne kind and up to 2.64 -2.78 Å fort he other kind, which yields an mean distance of 2.99 Å, which was observed. The dependence of the concentration of the statistical kind of meld, of the (Sb)4-, and the (Bi)4-kind from the concentration of the whole melt is given.By the model described the run of the measured mean coordination number and the mean distance versus concentration can be well explained.

Comparison of Certain Local Pseudopotentials and a New Proposal

2013 ◽  
Vol 665 ◽  
pp. 70-73
Author(s):  
Smruti J. Patel ◽  
A.Y. Vahora ◽  
B.Y. Thakore ◽  
Ashvin R. Jani
Keyword(s):  
Phonon Dispersion ◽  
Liquid Metals ◽  
Form Factors ◽  
Model Potential ◽  
Test Case ◽  
Nearest Neighbour ◽  
Core Radius ◽  
Phonon Dispersion Curves ◽  
Neighbour Distance

A new proposal of a local pseudopotential is put forwarded here depending on the concept of extended core radius in which half of the nearest neighbour distance is treated as effective core radius. There is no input of any property for fitting this parameter in this formalism. This pseudopotential is found to satisfy all the necessary requirements for applications. With this model potential we have evaluated the form factors for several bcc, fcc and hcp metals and achieved excellent agreement with previous results. On the same footing, we have examined other 14 local pseudo potentials also and on the basis of the comparison, the presently proposed pseudopotential is found to be much better. As a test case study, we have evaluated phonon dispersion curves of some liquid metals, viz. Na (Z = 1), Mg (Z = 2), Al (Z= 3) and Pb (Z = 4) and obtained quite satisfactory results.

scholarly journals Dominating lengthscales of zebrafish collective behaviour

2022 ◽  
Vol 18 (1) ◽  
pp. e1009394
Author(s):  
Yushi Yang ◽  
Francesco Turci ◽  
Erika Kague ◽  
Chrissy L. Hammond ◽  
John Russo ◽  
...  
Keyword(s):  
Collective Motion ◽  
Persistence Length ◽  
Three Dimensional ◽  
Temporal Correlation ◽  
Model System ◽  
Collective Behaviour ◽  
Living Systems ◽  
Nearest Neighbour ◽  
Length Scales ◽  
Neighbour Distance

Collective behaviour in living systems is observed across many scales, from bacteria to insects, to fish shoals. Zebrafish have emerged as a model system amenable to laboratory study. Here we report a three-dimensional study of the collective dynamics of fifty zebrafish. We observed the emergence of collective behaviour changing between ordered to randomised, upon adaptation to new environmental conditions. We quantify the spatial and temporal correlation functions of the fish and identify two length scales, the persistence length and the nearest neighbour distance, that capture the essence of the behavioural changes. The ratio of the two length scales correlates robustly with the polarisation of collective motion that we explain with a reductionist model of self–propelled particles with alignment interactions.

Effect of forager density on feeding rates in spring-staging Semipalmated Sandpipers (Calidris pusilla) using different foraging modes

2018 ◽  
Vol 96 (9) ◽  
pp. 996-1001 ◽  
Author(s):  
Ivana Novcic ◽  
Guy Beauchamp
Keyword(s):  
Delaware Bay ◽  
Nearest Neighbour ◽  
Feeding Rates ◽  
Stopover Site ◽  
Neighbour Distance ◽  
Short Intervals ◽  
Foraging Modes ◽  
Calidris Pusilla ◽  
Spring Stopover ◽  
Semipalmated Sandpipers

We examined the influence of the density of foragers on feeding rates of Semipalmated Sandpipers (Calidris pusilla (Linnaeus, 1766)) while using different foraging modes at a spring stopover site in Delaware Bay, USA. Using dynamic estimates of interindividual distances obtained at short intervals of time, we explored how forager density affected feeding rates when Semipalmated Sandpipers used visual pecking or tactile probing. Pecking rate significantly increased with interindividual distances, whereas probe rate was not affected by density. Our study also showed that in fast-moving foragers, such as Semipalmated Sandpipers, in which the number of nearby foragers and distance to the nearest neighbour continuously change throughout the foraging bout, pecking rates are more affected by nearest neighbour distance than by the number of foragers in their immediate vicinity. In addition, our study implies that foragers using different foraging modes might be differently affected by nearby competitors perhaps in response to prey disturbance by neighbours.

The effects of group size on the ingestive and social behaviour of grazing dairy cows

1999 ◽  
Vol 68 (4) ◽  
pp. 589-596 ◽  
Author(s):  
M. I. Rind ◽  
C.J. C. Phillips
Keyword(s):  
Dairy Cows ◽  
Group Size ◽  
Nearest Neighbour ◽  
Treatment Groups ◽  
Resting Behaviour ◽  
Biting Rate ◽  
Grazing Dairy Cows ◽  
Large Groups ◽  
Perceived Predation Risk ◽  
Lying Down

AbstractAn experiment was conducted with 48 dairy cows grazed in treatment groups of four, eight or 16 cows per group, whose grazing, social and resting behaviour was recorded over a 53-day period. Cows in groups of four stayed closer to their nearest neighbour, moved their head more rapidly from side to side during grazing and spent more time ruminating than cows in larger groups, suggesting that they were more vigilant against a perceived prédation risk. Cows in the group of 16 were more aggressive, maintained a greater distance to their nearest neighbour and had a faster rate of stepping while they grazed, compared with cows in smaller groups, suggesting increased inter-cow competition. They also spent longer grooming themselves, which normally acts as a displacement activity and may indicate increased stress. Cows in groups of eight had a faster biting rate when grazing than cows in small or large groups and they spent the longest time lying down. There were no effects of group size on milk production but across treatment groups the high yielding cows were the first to initiate grazing and to enter the milking parlour.

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