Perceptual Perspective Taking and Action Recognition

Robots that operate in social environments need to be able to recognise and understand the actions of other robots, and humans, in order to facilitate learning through imitation and collaboration. The success of the simulation theory approach to action recognition and imitation relies on the ability to take the perspective of other people, so as to generate simulated actions from their point of view. In this paper, simulation of visual perception is used to re-create the visual egocentric sensory space and egocentric behaviour space of an observed agent, and through this increase the accuracy of action recognition. To demonstrate the approach, experiments are performed with a robot attributing perceptions to and recognising the actions of a second robot

Discovery of Substructure in the Scatter-Broadened Image of Sgr A*

We have detected substructure within the smooth scattering disk of the celebrated Galactic Center radio source Sagittarius A* (SgrA*). We observed this structure at 1.3 cm wavelength with the Very Long Baseline Array together with the Green Bank Telescope, on baselines of up to 3000 km, long enough to completely resolve the average scattering disk. Such structure is predicted theoretically, as a consequence of refraction by large-scale plasma fluctuations in the interstellar medium. Along with the much-studied $\theta_\mathrm{d}\propto \lambda^2$ scaling of angular broadening $\theta_\mathrm{d}$ with observing wavelength $\lambda$, our observations indicate that the spectrum of interstellar turbulence is shallow, with an inner scale larger than 300 km. The substructure is consistent with an intrinsic size of about 1 mas at 1.3 cm wavelength, as inferred from deconvolution of the average scattering. Further observations of the substructure can set stronger constraints on the properties of scattering material and on the intrinsic size of SgrA*. These constraints will guide understanding of effects of scatter-broadening and emission physics of the black hole, in images with the Event Horizon Telescope at millimeter wavelengths.Comment: 5 pages, 5 figures, accepted by Astrophysical Journal Letters; minor corrections to the text and figures are introduce

Dominant moving species in the formation of amorphous NiZr by solid-state reaction

The displacements of W and Hf markers have been monitored by backscattering of MeV He to study the growth of the amorphous NiZr phase by solid-state reaction. We find that the Ni is the dominant moving species in this reaction

Correlation between cohesive energy and mixing rate in ion mixing of metallic bilayers

We have compared the mixing rate of several 5d-4d metal bilayers which form ideal solutions. We observe a strong correlation between the mixing rate and the average cohesive energy of each bilayer. A model based on the thermal spike concept is proposed to explain this behavior. The model leads to a general expression describing mixing rates in metallic bilayers

Influence of chemical driving forces in ion mixing of metallic bilayers

The effective interdiffusion coefficient of metallic bilayers under ion irradiation has been correlated with the heat of mixing of corresponding binary alloys. The results are interpreted according to Darken's theory of chemically enhanced diffusion

Universality and correlations in individuals wandering through an online extremist space

The 'out of the blue' nature of recent terror attacks and the diversity of apparent motives, highlight the importance of understanding the online trajectories that individuals follow prior to developing high levels of extremist support. Here we show that the physics of stochastic walks, with and without temporal correlation, provides a unifying description of these online trajectories. Our unique dataset comprising all users of a global social media site, reveals universal characteristics in individuals' online lifetimes. Our accompanying theory generates analytical and numerical solutions that describe the characteristics shown by individuals that go on to develop high levels of extremist support, and those that do not. The existence of these temporal and also many-body correlations suggests that existing physics machinery can be used to quantify and perhaps mitigate the risk of future events

Effect of thermodynamics on ion mixing

Ion mixing of elemental 4d-5d metallic bilayers at 77 K by 600 keV Xe + + ions has been studied to test the validity of the phenomenological model of ion mixing that predicts a dependence on the chemical heats of mixing, DeltaHmix, and on the cohesive energies, DeltaHcoh, of the bilayer elements. A series of samples was chosen to minimize the variation in kinematical properties between samples while maximizing the variation in heats of mixing. The experimental results agree well with the model's predictions, and the experimentally determined constants K1=0.034 Å and K2=27 agree with those of previous work