University of Oxford

Abstract: The observed large mixing angles in the lepton sector may be the first signal for the presence of a non-Abelian family symmetry. However, to obtain the significant differences between the mixing of the neutrino and charged fermion sectors, the vacuum expectation values involved in the breaking of such a symmetry in the two sectors must be misaligned. We investigate how this can be achieved in models with an SU ( 3 ) f family symmetry consistent with an underlying GUT. We show that such misalignment can be achieved naturally via the see-saw mechanism. We construct a specific example in which the vacuum (mis)alignment is guaranteed by additional symmetries. This model generates a fermion mass structure consistent with all quark and lepton masses and mixing angles. Neutrino mixing is close to bi-tri-maximal mixing.

Abstract: Confocal microscopes unlike their conventional counterparts have the ability to optically ‘section’ thick specimens. However the resolution and optical sectioning can be severely degraded by system or specimen-induced aberrations. The use of high aperture lenses further exacerbates the difficulties. We will describe an adaptive optics solution to this fundamental problem.

Abstract: We present spectra of the black hole binary A0620-00 taken at Hα and Hβ to study the distribution of emission-line flux from its accretion disc. Using the spectra of Hα, we have measured the K-type companion star's radial velocity semi-amplitude and rotational broadening to be K 2 =433±3 km s −1 and v sin i=83±5 km s −1 . Accounting for the Roche-lobe geometry of the companion, the rotational broadening gives the mass ratio q=M 2 /M 1 =0.06 7±0.01. The disc contributes 6±3 per cent of the light at Hα and 17±3 per cent at Hβ, with the K star providing the rest. The masses of the compact object and K star derived from our values of K 2 and q are M 1 =(3.09±0.09)sin −3 i M ○. and M 2 =(0.21±0.04)sin −3 i M ○.

Abstract: The chronic drainage of lymph and cells from a thoracic duct fistula in rats results in a reduction in the weight of all the lymph nodes and of their content of small lymphocytes. The primary immune response to tetanus toxoid or sheep erythrocytes is severely depressed or abolished in such animals. This unresponsive state is related to the loss of lymphocytes from the thoracic duct fistula and, not to stress factors ensuing from the trauma of operation and restraint; it can be reversed by injecting inocula which contain almost exclusively small lymphocytes. In contrast to the severe impairment of the primary immune response in lymphocyte-depleted rats, such animals show a normal response to a second injection of tetanus toxoid. The mechanism by which small lymphocytes mediate the primary immune response is discussed.

Abstract: Ratings were made by 120 subjects of 18 video-tapes in which verbal and non-verbal cues for Inferior, Equal and Superior were varied and combined in a 3 times 3 design. The typed messages (verbal alone) were rated by further subjects, as were video-tapes of a performer reading numbers (non-verbal alone); the two sets of cues alone had identical effects on ratings. In combination, both kinds of cue had a reduced effect, but it was found that non-verbal cues now had 4.3 times the effect of verbal cues on shifts of ratings, and accounted for 10.3 times as most variance; verbal cues were only able to act as multipliers of consistent nonverbal cues. There was little evidence of double-bind effects. Analysis of individual differences showed that females were relatively more responsive to non-verbal compared with verbal cues, and that more neurotic subjects found the combination of Superior (non-verbal) with Inferior (verbal) unpleasant, and responded more to verbal cues for Inferior-Superior.