Quaternionic Spin

We rewrite the standard 4-dimensional Dirac equation in terms of quaternionic 2-component spinors, leading to a formalism which treats both massive and massless particles on an equal footing. The resulting unified description has the correct particle spectrum to be a generation of leptons, with the correct number of spin/helicity states. Furthermore, precisely three such generations naturally combine into an octonionic description of the 10-dimensional massless Dirac equation, as discussed in previous work.Comment: LaTeX2e, 15 pages, 1 PS figure; to appear in Clifford '99 proceeding

Undergraduate leadership education for dentistry: preparing for practice

This paper seeks to explore the topic of leadership education in undergraduate dental programmes. ‘Management and leadership’ has been recognised as one of the four main domains in the UK General Dental Council ‘Preparing for Practice’ document and is identified in the ADEE ‘Profile and Competences for the Graduating European Dentist’ document under the domain of ‘Professionalism’. Many dental schools throughout Europe are now planning for the inclusion of leadership education. Questions are therefore raised about how this might be envisaged: what should undergraduates be prepared for and how should it be done? This paper draws on emerging debates found within the wider, non-dental specific leadership studies literature that challenge traditionally held views of leadership and models of leadership education found currently in dentistry. It is argued that all students should be exposed to distributed and inclusive leadership practices to prepare them for the challenges they will find in their everyday practising careers. It is proposed that there is an opportunity to engage with dental practitioners (at all levels) to encourage the development of experiential, active learning to bring alive leadership in practice for dental students

Can Virtual Reality Trainers Improve the Compliance Discrimination Abilities of Trainee Surgeons?

The assessment of tissue compliance using a handheld tool is an important skill in medical areas such as laparoscopic and dental surgery. The increasing prevalence of virtual reality devices raises the question of whether we can exploit these systems to accelerate the training of compliance discrimination in trainee surgeons. We used a haptic feedback device and stylus to assess the abilities of naïve participants to detect compliance differences with and without knowledge of results (KR) (groups 1 and 2), as well as the abilities of participants who had undergone repetitive training over several days (group 3). Kinematic analyses were carried out to objectively measure the probing action. Untrained participants had poor detection thresholds (mean just noticeable difference, JND = 33%), and we found no effect of KR (provided after each trial) on performance (mean JND = 35%). Intensive training dramatically improved group performance (mean JND = 12%). Probing action (in particular, slower movement execution) was associated with better detection thresholds, but training did not lead to systematic changes in probing behaviour. These findings set a benchmark for training systems that act to increase perceptual sensitivity and guide the learner toward optimal movement strategies to improve discrimination

Scattering of a relativistic scalar particle by a cusp potential

We solve the Klein-Gordon equation in the presence of a spatially one-dimensional cusp potential. The scattering solutions are obtained in terms of Whittaker functions and the condition for the existence of transmission resonances is derived. We show the dependence of the zero-reflection condition on the shape of the potential. In the low momentum limit, transmission resonances are associated with half-bound states. We express the condition for transmission resonances in terms of the phase shifts.Comment: To appear in Physics Letters

Small Kerr-anti-de Sitter black holes are unstable

Superradiance in black hole spacetimes can trigger instabilities. Here we show that, due to superradiance, small Kerr-anti-de Sitter black holes are unstable. Our demonstration uses a matching procedure, in a long wavelength approximation.Comment: 7 pages, 1 figure, RevTeX

Auxiliary Fields for Super Yang-Mills from Division Algebras

Division algebras are used to explain the existence and symmetries of various sets of auxiliary fields for super Yang-Mills in dimensions $d=3,4,6,10$. (Contribution to G\"ursey Memorial Conference I: Strings and Symmetries)Comment: 7 pages, plain TeX, CERN-TH.7470/9

Octonionic representations of Clifford algebras and triality

The theory of representations of Clifford algebras is extended to employ the division algebra of the octonions or Cayley numbers. In particular, questions that arise from the non-associativity and non-commutativity of this division algebra are answered. Octonionic representations for Clifford algebras lead to a notion of octonionic spinors and are used to give octonionic representations of the respective orthogonal groups. Finally, the triality automorphisms are shown to exhibit a manifest \perm_3 \times SO(8) structure in this framework.Comment: 33 page

Capturing differences in dental training using a virtual reality simulator

Virtual reality simulators are becoming increasingly popular in dental schools across the world. But to what extent do these systems reflect actual dental ability? Addressing this question of construct validity is a fundamental step that is necessary before these systems can be fully integrated into a dental school's curriculum. In this study, we examined the sensitivity of the Simodont (a haptic virtual reality dental simulator) to differences in dental training experience. Two hundred and eighty-nine participants, with 1 (n = 92), 3 (n = 79), 4 (n = 57) and 5 (n = 61) years of dental training, performed a series of tasks upon their first exposure to the simulator. We found statistically significant differences between novice (Year 1) and experienced dental trainees (operationalised as 3 or more years of training), but no differences between performance of experienced trainees with varying levels of experience. This work represents a crucial first step in understanding the value of haptic virtual reality simulators in dental education

Distributional Modes for Scalar Field Quantization

We propose a mode-sum formalism for the quantization of the scalar field based on distributional modes, which are naturally associated with a slight modification of the standard plane-wave modes. We show that this formalism leads to the standard Rindler temperature result, and that these modes can be canonically defined on any Cauchy surface.Comment: 15 pages, RevTe