Enhanced microcomputer operation of X-ray diffractometers and subsequent applications.

The work described within this thesis is mainly concerned with the solution and refinement of the molecular structures of a variety of novel compounds. A number of X-ray and neutron diffractometers have been utilised for the analysis of specific compounds, depending on the nature of the investigation. Each of the instruments represented differing levels of computer automation and instrumentation. A powder diffractometer, representing old technology was interfaced to a microcomputer to enhance the instruments performance. A brief overview is given of the numerical processes involved in the elucidation and refinement of molecular structures from X-ray and neutron diffraction data. Particular attention has been placed on the role of computers to perform these calculations. The operation of the diffractometers employed in this study has been discussed comparing the benefits of each. A detailed report of the techniques used to enhance the low resolution diffractometer and of the experiments performed to highlight the increased performance has been included. Single crystal and powder diffraction studies were made of a wide variety of crystalline materials ranging from steroids to organometallic compounds. The X-ray structures were solved using Direct and Patterson vector methods from experimental data collected on a four circle diffractometer at Aberdeen University. Neutron diffraction experiments, performed at the Rutherford Appleton Laboratory, were commissioned to determine and refine the positions of the hydrogen atoms of two known structures, previously solved by Xray studies. Finally a critical evaluation of current computer automated diffractometers is presented, highlighting the new areas of instrument development

Hume and Reid: A common legacy

Lord Sutherland provides a lucid introduction to factors in the cultural legacy which David Hume and Thomas Reid inherited. These factors included Calvinism and the characteristic Scottish practice of reasoning from first principles. He then goes on to unfold the continuing relevance of Hume’s ideas to contemporary debate concerning the family, education and civil society

Direct Measurement of the Quantum Wavefunction

Central to quantum theory, the wavefunction is the complex distribution used to completely describe a quantum system. Despite its fundamental role, it is typically introduced as an abstract element of the theory with no explicit definition. Rather, physicists come to a working understanding of the wavefunction through its use to calculate measurement outcome probabilities via the Born Rule. Presently, scientists determine the wavefunction through tomographic methods, which estimate the wavefunction that is most consistent with a diverse collection of measurements. The indirectness of these methods compounds the problem of defining the wavefunction. Here we show that the wavefunction can be measured directly by the sequential measurement of two complementary variables of the system. The crux of our method is that the first measurement is performed in a gentle way (i.e. weak measurement) so as not to invalidate the second. The result is that the real and imaginary components of the wavefunction appear directly on our measurement apparatus. We give an experimental example by directly measuring the transverse spatial wavefunction of a single photon, a task not previously realized by any method. We show that the concept is universal, being applicable both to other degrees of freedom of the photon (e.g. polarization, frequency, etc.) and to other quantum systems (e.g. electron spin-z quantum state, SQUIDs, trapped ions, etc.). Consequently, this method gives the wavefunction a straightforward and general definition in terms of a specific set of experimental operations. We expect it to expand the range of quantum systems scientists are able to characterize and initiate new avenues to understand fundamental quantum theory

Multiband superconductivity in NbSe_2 from heat transport

The thermal conductivity of the layered s-wave superconductor NbSe_2 was measured down to T_c/100 throughout the vortex state. With increasing field, we identify two regimes: one with localized states at fields very near H_c1 and one with highly delocalized quasiparticle excitations at higher fields. The two associated length scales are most naturally explained as multi-band superconductivity, with distinct small and large superconducting gaps on different sheets of the Fermi surface.Comment: 2 pages, 2 figures, submitted to M2S-Rio 2003 Proceeding

Listening and learning : the reciprocal relationship between worker and client

The relationship between worker and client has for the best part of 100 years been the mainstay of probation, and yet has recently been eroded by an increased emphasis on punishment, blame and managerialism. The views of offenders are in direct contradiction to these developments within the criminal justice system and this article argues that only by taking account of the views of those at the 'coal face' will criminologists, policy makers and practitioners be able to effect real change in crime rates. The article thus focuses on the views of a sample of previously persistent offenders in Scotland about offending, desistance and how the system can help them. It explores not only their need for friendship and support in youth but also the close association between relationships and the likelihood of offending. It also demonstrates the views of offenders themselves about the importance of the working relationship with supervising officers in helping them desist from crime. The article concludes that the most effective way of reducing offending is to re-engage with the message of the Probation Act of 100 years ago, namely, to 'advise, assist and befriend' offenders rather than to 'confront, challenge and change' offending behaviour

Cold Fermi-gas with long range interaction in a harmonic trap

We study equilibrium density and spin density profiles for a model of cold one-dimensional spin 1/2 fermions interacting via inverse square interaction and exchange in an external harmonic trap. This model is the well-known spin-Calogero model (sCM) and its fully nonlinear collective field theory description is known. We extend the field theory description to the presence of an external harmonic trap and obtain analytic results for statics and dynamics of the system. For instance, we find how the equilibrium density profile changes upon tuning the interaction strength. The results we obtain for equilibrium configurations are very similar to the ones obtained recently by Ma and Yang [1] for a model of fermions with short ranged interactions. Our main approximation is the neglect of the terms of higher order in spatial derivatives in equations of motion - gradientless approximation [2]. Within this approximation the hydrodynamic equations of motion can be written as a set of decoupled forced Riemann-Hopf equations for the dressed Fermi momenta of the model. This enables us to write analytical solutions for the dynamics of spin and charge. We describe the time evolution of the charge density when an initial non-equilibrium profile is created by cooling the gas with an additional potential in place and then suddenly removing the potential. We present our results as a simple "single-particle" evolution in the phase-space reminiscing a similar description of the dynamics of non-interacting one-dimensional fermions.Comment: 11 pages, 5 figures (figure typo corrected and references added

Spectroscopic characterization of model compounds, reactants, and byproducts connected with an isocyanate production chain

Aromatic amines and amine hydrochloride salts play an important part in certain large-scale isocyanate production chains. For the first time, via a combination of periodic-DFT calculations, infrared spectroscopy, and inelastic neutron scattering, this work provides a comprehensive vibrational assignment of 4-benzylaniline (C6H4CH2C6H4NH2), 4,4′-methylenedianiline (H2NC6H4CH2C6H4NH2), and their associated amine hydrochloride salts. Deuterated analogues are additionally utilized to assist vibrational assignments. The heightened awareness of vibrational transitions for these technically relevant reagents and byproducts provides the opportunity to apply infrared spectroscopy as an in-line diagnostic tool within the industrial-scale process operation

The social anatomy of 'collusion'

This paper offers a conceptual analysis of collusion, the often overlooked relative of plagiarism in debates on academic integrity. Considered as an inherently social phenomenon, we present the results of a systematic effort to understand the anatomy of collusion. The term’s meanings and associated governance practices are compared for contexts outside Higher Education (HE). These are considered alongside a thematic analysis of publicly available UK university academic integrity documentation that specifies for students what counts as collusion. We indicate how current guideline practice can (1) appear incomplete by concentrating on classroom peers, (2) create blurred boundaries around useful collaboration, peer review and dishonest practice and (3) may be so unrealistic as to have unwelcome, unintended consequences for students and staff. Taking an ecological perspective on the conditions of collusion emphasises how these guidelines - by seeking to constrain social interactions around assignment work - may create an uncomfortable incoherence between their prescriptions and well-established patterns of study

Late Pleistocene sediments, landforms and events in Scotland: a review of the terrestrial stratigraphic record

Lithostratigraphical studies coupled with the development of new dating methods has led to significant progress in understanding the Late Pleistocene terrestrial record in Scotland. Systematic analysis and re-evaluation of key localities have provided new insights into the complexity of the event stratigraphy in some regions and the timing of Late Pleistocene environmental changes, but few additional critical sites have been described in the past 25 years. The terrestrial stratigraphic record remains important for understanding the timing, sequence and patterns of glaciation and deglaciation during the last glacial/interglacial cycle. Former interpretations of ice-free areas in peripheral areas during the Last Glacial Maximum (LGM) are inconsistent with current stratigraphic and dating evidence. Significant challenges remain to determine events and patterns of glaciation during the Early and Middle Devensian, particularly in the context of offshore evidence and ice sheet modelling that indicate significant build-up of ice throughout much of the period. The terrestrial evidence broadly supports recent reconstructions of a highly dynamic and climate-sensitive British–Irish Ice Sheet (BIIS), which apparently reached its greatest thickness in Scotland between 30 and 27ka, before the global LGM. A thick (relative to topography) integrated ice sheet reaching the shelf edge with a simple ice-divide structure was replaced after the LGM by a much thinner one comprising multiple dispersion centres and a more complex flow structure