2,271 research outputs found
Evidence of strategic periodicities in collective conflict dynamics
We analyze the timescales of conflict decision-making in a primate society.
We present evidence for multiple, periodic timescales associated with social
decision-making and behavioral patterns. We demonstrate the existence of
periodicities that are not directly coupled to environmental cycles or known
ultraridian mechanisms. Among specific biological and socially-defined
demographic classes, periodicities span timescales between hours and days, and
many are not driven by exogenous or internal regularities. Our results indicate
that they are instead driven by strategic responses to social interaction
patterns. Analyses also reveal that a class of individuals, playing a critical
functional role, policing, have a signature timescale on the order of one hour.
We propose a classification of behavioral timescales analogous to those of the
nervous system, with high-frequency, or -scale, behavior occurring on
hour-long scales, through to multi-hour, or -scale, behavior, and,
finally periodicities observed on a timescale of days.Comment: 22 pages, 7 figures, 1 table. Accepted for publication in Journal of
the Royal Society Interfac
Inductive Game Theory and the Dynamics of Animal Conflict
Conflict destabilizes social interactions and impedes cooperation at multiple scales of biological organization. Of fundamental interest are the causes of turbulent periods of conflict. We analyze conflict dynamics in an monkey society model system. We develop a technique, Inductive Game Theory, to extract directly from time-series data the decision-making strategies used by individuals and groups. This technique uses Monte Carlo simulation to test alternative causal models of conflict dynamics. We find individuals base their decision to fight on memory of social factors, not on short timescale ecological resource competition. Furthermore, the social assessments on which these decisions are based are triadic (self in relation to another pair of individuals), not pairwise. We show that this triadic decision making causes long conflict cascades and that there is a high population cost of the large fights associated with these cascades. These results suggest that individual agency has been over-emphasized in the social evolution of complex aggregates, and that pair-wise formalisms are inadequate. An appreciation of the empirical foundations of the collective dynamics of conflict is a crucial step towards its effective management
Dielectric constants of bulk ferroelectric PZTmeasured by terahertz time-domain spectroscopy
The complex permittivity of bulk ceramic ferroelectric of nominal composition PbZr0.4Ti0.6O3 was measured in the range 0.2–2 THz using transmission time-domain spectroscopy. The results indicate strong absorption and dispersion in this frequency range as often seen in highly disordered and polar materials. The results are compared to equivalent thin film data in the literature, and significant differences in the real and imaginary permittivity suggest that substrate clamping and degree of polarisation of the ferroelectric thin film materials affect dielectric properties even at these high frequencies
Verification of the indoor GPS system, by comparison with calibrated coordinates and by angular reference
This paper details work carried out to verify the dimensional measurement performance of the Indoor GPS (iGPS) system; a network of Rotary-Laser Automatic Theodolites (R-LATs). Initially tests were carried out to determine the angular uncertainties on an individual R-LAT transmitter-receiver pair. A method is presented of determining the uncertainty of dimensional measurement for a three dimensional coordinate measurement machine. An experimental procedure was developed to compare three dimensional coordinate measurements with calibrated reference points. The reference standard used to calibrate these reference points was a fringe counting interferometer with the multilateration technique employed to establish three dimensional coordinates. This is an extension of the established technique of comparing measured lengths with calibrated lengths. The method was found to be practical and able to establish that the expanded uncertainty of the basic iGPS system was approximately 1 mm at a 95% confidence level. Further tests carried out on a highly optimized version of the iGPS system have shown that the coordinate uncertainty can be reduced to 0.25 mm at a 95% confidence level
High resolution imaging of the anomalous flux-ratio gravitational lens system CLASS B2045+265: Dark or luminous satellites?
The existence of flux-ratio anomalies between fold and cusp images in
galaxy-scale strong-lens systems has led to an interpretation based on the
presence of a high mass-fraction of cold-dark-matter (CDM) substructures around
galaxies, as predicted by numerical N-body simulations. The flux-ratio anomaly
is particularly evident in the radio-loud quadruple gravitational lens system
CLASS B2045+265. In this paper, new high-resolution radio, optical, and
infrared imaging of B2045+265 is presented which sheds more light on this
anomaly and its possible causes. First, deep Very Long Baseline Array
observations show very compact images, possibly with a hint of a jet, but with
no evidence for differential scattering or scatter broadening. Second, optical
and infrared observations with the Hubble Space Telescope and through
Adaptive-Optics imaging with the W. M. Keck Telescope, show a previously
undiscovered object -- interpreted as a (tidally disrupted) dwarf satellite
based on its colours and slight extension -- between the main lens galaxy and
the three anomalous flux-ratio images. Third, colour variations in the
early-type lens galaxy indicate recent star-formation, possibly the result of
secondary infall of gas-rich satellites. A population of such galaxies around
the lens system could explain the previously discovered strong [O II] emission.
However, spiral structure and/or normal star formation in the lens galaxy
cannot be excluded. In light of these new data, we propose a lens model for the
system, including the observed dwarf satellite, which reproduces all positional
and flux-ratio constraints, without the need for additional CDM substructure.
[abridged]Comment: 10 pages, 6 figures, accepted for publication in MNRA
Growth and characterization of heteroepitaxial La-substituted BaSnO films on SrTiO (001) and SmScO (110) substrates
Heteroepitaxial growth of BaSnO (BSO) and BaLaSnO (x = 7
%) (LBSO) thin films on different perovskite single crystal (SrTiO (001)
and SmScO (110)) substrates has been achieved by Pulsed Laser Deposition
(PLD) under optimized deposition conditions. X-ray diffraction measurements
indicate that the films on either of these substrates are relaxed due to the
large mismatch and present a high degree of crystallinity with narrow rocking
curves and smooth surface morphology while analytical quantification by proton
induced x-ray emission (PIXE) confirms the stoichiometric La transfer from a
polyphasic target, producing films with La contents above the bulk solubility
limit. The films show degenerate semiconducting behavior on both substrates,
with the observed room temperature resistivities, Hall mobilities and carrier
concentrations of 4.4 , 10.11 , and 1.38
on SmScO and 7.8 , 5.8 , and 1.36 on SrTiO ruling out any extrinsic
contribution from the substrate. The superior electrical properties observed on
the SmScO3 substrate are attributed to reduction in dislocation density from
the lower lattice mismatch.Comment: 11 pages, 3 figures, supplementary informations 2 figure
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