The ductility and strength of spider draglines means that they outperform the best synthetic fibres, but surprisingly little is known about the torsional properties of this remarkable filament. Unlike a mountain climber swinging from a rope, a spider suspended from its silk thread hardly ever twists. Here we show that a spider dragline has a torsional shape 'memory' in that it can reversibly and totally recover its initial form without any external stimulus; its observed relaxation dynamics indicate that these biological molecules have successively different torsional constants.

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It is shown experimentally that one can image an object embedded in a turbid medium by probing the medium with light with a rotating linear polarization. This method permits the ballistic photons to be isolated from the large background of photons that have been multiply scattered by optically dense anisotropic scatterers. This technique achieves a good signal-to-noise ratio even with a low-power continuous laser, leading to images with a diffraction-limited resolution comparable with that obtained in optically homogeneous media.

The design of an 'orbital angular momentum (OAM) antenna' based on an original phase shifter and power divider combination at 2.5 GHz is presented. A prototype is manufactured and characterised based on return loss, radiation and phase patterns. Both simulation and experimental results evidence the properties of waves carrying OAM. This OAM antenna is simple, compact and easy to realise, which makes it suitable for radio communications and radar applications.Introduction: Orbital angular momentum (OAM) has been proposed to improve spectral efficiency [1][2][3][4] in radio communications, by creating multiple sub-channels of propagation corresponding to the twisting degree of the electromagnetic wave.Whereas the phase of a usual plane wave is constant on the wavefront, the phase α of OAM waves undergoes a linear variation along the angular coordinate w (roll angle): α = ℓw, where ℓ is an integer called the 'topological charge' or the order of the OAM mode. The field hence varies as e −jℓw .f ℓ (r).e −jkz , where k is the wave vector, z is the propagation axis and f ℓ (r) represents the field variation along the radial coordinate.

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