A case study of argumentation at undergraduate level in history

This article examines two essays by undergraduate students in the first year of study in History at a university in the UK. It also draws on documentary evidence from the department in question and interviews with the students themselves to paint a picture of the way argumentation operates at this level. While no firm conclusions can be drawn, the evidence suggests a department with a high degree of awareness of the importance of argument and argumentation in studying History; and students who are aware and articulate about the problem facing them in constructing essays in the discipline. Suggestions are made about induction into the epistemological and argumentative demands of undergraduate study

Development of solution techniques for nonlinear structural analysis

Nonlinear structural solution methods in the current research literature are classified according to order of the solution scheme, and it is shown that the analytical tools for these methods are uniformly derivable by perturbation techniques. A new perturbation formulation is developed for treating an arbitrary nonlinear material, in terms of a finite-difference generated stress-strain expansion. Nonlinear geometric effects are included in an explicit manner by appropriate definition of an applicable strain tensor. A new finite-element pilot computer program PANES (Program for Analysis of Nonlinear Equilibrium and Stability) is presented for treatment of problems involving material and geometric nonlinearities, as well as certain forms on nonconservative loading

Optical-radar imaging of scale models for studies in asteroid astronomy

During the past five years, delay-Doppler radar has become the primary technique for studying the structure of Earth-crossing asteroids. None of these objects has yet been visited by spacecraft, so ground-truth test cases are lacking. A laboratory system is described that provides optical-radar images at 0.1-mm resolution. These data are analogous to the highest-resolution asteroid radar images currently available and provided realistic test cases for developing signal-processing techniques. The system can be thought of as a 1/188,000 scale model of the Arecibo radar, or a 1/52,800 scale model of the Goldstone radar

The metabolism of beta-(3,4 dihydroxyphenyl)-L-alanine by plants

Methods for the detection and characterisation of DOPA derivatives in plant tssues have been investigated. In relation to this study, several methods for the production of possible naturally occurring derivatives were explored. The most success was achieved by feeding L-DOPA to Pislum sativum seeds which were then allowed to germinate for a short periods. Five compounds were isolated from the treated seedlings and one of them was shown to be identical to the DOPA glucoside which had previously been reported in the testas of broad been (Vicia faba) seeds (5). The same compound was later identified in the cotyledons of dormant bean seeds, and its structure shown to be B - (3-B-D - glucopyranosyloxy) - 4 - hydroxyphenyl) - L - alanine. The chemical nature of the other compounds was also investigated and tentative deductions made for their structures. A number of 0 and N - methylated derivatives of DOPA have been synthesised chemically. Their properties have been recorded and whereby isomeric 0 - substituted DOPA derivatives may be distinguished are outlined.Using the information from the preliminary studies, the distribution of DOPA and its derivatives in about 200 different species of plants have been investigated. This has revealed that DOPA derivatives are rare in plants, although free DOPA has been detected in a number of leguminous species and in species grouped within the order of Centrospermae. This latter discovery adds weight to the suggestion that DOPA is a precursor of the characteristic red-violet and yellow pigments which are found within the Centroapermae.A detailed study the distribution of DOPA and related compounds in the broad bean has been undertaken. Variations in the concentrations of the compounds throughout the growth cycle have been studied qualitatively using chromatographic and electrophoretic techniques, and quantatively, using an iodine colourimetric procedure and by ran exchange chromatography. The presence of DOPA in the tissues of leguminous species is often associated with the formation of dark brown or black pigments. Observations on the biogenesis, histology and chemical nature of these pigments are described. Comparison of the chemical and physical properties of plant pigments with those of biosynthetically prepared melanins showed that there are considerable differences. The plant pigments do not appear to be similar to animal melanins. The enzyme in dandelion (Taraxacum officinale) leaves which catalyses the deamination of DOPA has been studied. This appears to be labile, particulate and distinct from the phenylalanine ammonia lyase which is also present in the leaves.<p

Non-destructive spatial heterodyne imaging of cold atoms

We demonstrate a new method for non-destructive imaging of laser-cooled atoms. This spatial heterodyne technique forms a phase image by interfering a strong carrier laser beam with a weak probe beam that passes through the cold atom cloud. The figure of merit equals or exceeds that of phase-contrast imaging, and the technique can be used over a wider range of spatial scales. We show images of a dark spot MOT taken with imaging fluences as low as 61 pJ/cm^2 at a detuning of 11 linewidths, resulting in 0.0004 photons scattered per atom.Comment: text+3 figures, submitted to Optics Letter

Fermionic solution of the Andrews-Baxter-Forrester model II: proof of Melzer's polynomial identities

We compute the one-dimensional configuration sums of the ABF model using the fermionic technique introduced in part I of this paper. Combined with the results of Andrews, Baxter and Forrester, we find proof of polynomial identities for finitizations of the Virasoro characters $\chi_{b,a}^{(r-1,r)}(q)$ as conjectured by Melzer. In the thermodynamic limit these identities reproduce Rogers--Ramanujan type identities for the unitary minimal Virasoro characters, conjectured by the Stony Brook group. We also present a list of additional Virasoro character identities which follow from our proof of Melzer's identities and application of Bailey's lemma.Comment: 28 pages, Latex, 7 Postscript figure

Asymmetric Ejecta of Cool Supergiants and Hypergiants in the Massive Cluster Westerlund 1

We report new 5.5 GHz radio observations of the massive star cluster Westerlund 1, taken by the Australia Telescope Compact Array, detecting nine of the ten yellow hypergiants (YHGs) and red supergiants (RSGs) within the cluster. Eight of nine sources are spatially resolved. The nebulae associated with the YHGs Wd1-4a, -12a and -265 demonstrate a cometary morphology - the first time this phenomenon has been observed for such stars. This structure is also echoed in the ejecta of the RSGs Wd1-20 and -26; in each case the cometary tails are directed away from the cluster core. The nebular emission around the RSG Wd1-237 is less collimated than these systems but once again appears more prominent in the hemisphere facing the cluster. Considered as a whole, the nebular morphologies provide compelling evidence for sculpting via a physical agent associated with Westerlund 1, such as a cluster wind