The sum rule for the first moment of the polarised (virtual) photon structure function g γ 1 (x, Q 2 ; K 2) is revisited in the light of proposals for future e + e − colliders. The sum rule exhibits an array of phenomena characteristic of QCD: for real photons (K 2 = 0) electromagnetic gauge invariance constrains the first moment to vanish; the limit for asymptotic photon virtuality (m 2 ρ ≪ K ...

Several techniques have been proposed and used for the rotation or alignment of microparticles in optical tweezers. In every case the optical torque results from the exchange of angular momentum between the beam and the particle, and, in principle, can be measured by purely optical means. Measurement of this torque could be useful for quantitative measurements in biological systems and is requi...

We discuss two aspects of polarisation in hard exclusive meson production: the leading-twist selection rule for the meson helicity, and the different partial waves of a ππ-pair which may or may not be due to the decay of a ρ. 1 Helicity in vector meson production The first half of this talk is about exclusive electroproduction of a ρ (or any other light vector meson), ep → ep + ρ, in the Bjorke...

Using a full-potential ab-initio technique I study the electronic and magnetic properties of the (001) surfaces of the half-Heusler alloys, NiMnSb, CoMnSb and PtMnSb and of the full-Heusler alloys Co 2 MnGe, Co 2 MnSi and Co 2 CrAl. The MnSb terminated surfaces of the half-Heusler compounds present properties similar to the bulk compounds and, although the half-metallicity is lost, an important...

Butterflies of the genus Papilio have polarisation-sensitive photoreceptors in all regions of the eye, and different spectral types of receptor are sensitive to different e-vector orientations. We have studied the consequences of this eye design for colour vision in behavioural tests and find that Papilio spp. see false colours due to the polarisation of light. They discriminate between vertica...

Polarised stereoscopic projection involves the polarisation of the two projected images in orthogonal directions e.g. +/45 degrees for linear polarisation, or clockwise and counter-clockwise for circular polarisation. When LCD projectors are used for polarised stereoscopic projection it is important to take into consideration the fact that the output of these types of projectors is already pola...

Model polarisation potentials for use in calculating positron-molecule cross sections are often based on approximations in which terms that depend on the sign of the charge of the projectile are neglected. Thus, these potentials do not fully distinguish between electron and positron scattering. The validity of using such potentials for positronH2 collisions is investigated by performing scatter...

We have analysed the angular power spectra of the Parkes radio continuum and polarisation survey of the Southern galactic plane at 2.4 GHz. We have found that in the multipole range l = 40–250 the angular power spectrum of the polarised intensity is well described by a power-law spectrum with fitted spectral index αL = 2.37 ± 0.21. In the same multipole range the angular power spectra of the E ...

We report a study in which Andreev reflection using a Nb point contact is used to measure the transport spin polarisation of the 4d itinerant ferromagnet SrRuO3. By performing the study in high quality thin films with residual resistivities less than 7μΩ-cm, we ensure that the study is done in the ballistic limit, a regime which is difficult to reach in oxide ferromagnets. The degree of transpo...

Planar polarity describes the coordinated polarisation of cells or structures in the plane of a tissue. The patterning mechanisms that underlie planar polarity are well characterised in Drosophila, where many events are regulated by two pathways: the 'core' planar polarity complex and the Fat/Dachsous system. Components of both pathways also function in vertebrates and are implicated in diverse...