On the dual-cone nature of the conical refraction phenomenon

In conical refraction (CR), a focused Gaussian input beam passing through a biaxial crystal and parallel to one of the optic axes is transformed into a pair of concentric bright rings split by a dark (Poggendorff) ring at the focal plane. Here, we show the generation of a CR transverse pattern that does not present the Poggendorff fine splitting at the focal plane, i.e., it forms a single light ring. This light ring is generated from a nonhomogeneously polarized input light beam obtained by using a spatially inhomogeneous polarizer that mimics the characteristic CR polarization distribution. This polarizer allows modulating the relative intensity between the two CR light cones in accordance with the recently proposed dual-cone model of the CR phenomenon. We show that the absence of interfering rings at the focal plane is caused by the selection of one of the two CR cones. (C) 2015 Optical Society of America

An investigation into the nature and consequences of teachers' implicit philosophies of science

The aims of this study were to investigate the beliefs concerning the philosophy of science held by practising science teachers and to relate those beliefs to their pupils' understanding of the philosophy of science. Three philosophies of science, differing in the way they relate experimental work to other parts of the scientific enterprise, are described. By the use of questionnaire techniques, teachers of four extreme types were identified. These are: the H type or hypothetico-deductivist teacher, who sees experiments as potential falsifiers of hypotheses or of logical deductions from them; the I type or inductivist teacher, who regards experiments mainly as a way of increasing the range of observations available for recording before patterns are noted and inductive generalisation is carried out; the V type or verificationist teacher, who expects experiments to provide proof and to demonstrate the truth or accuracy of scientific statements; and the 0 type, who has no discernible philosophical beliefs about the nature of science or its methodology. Following interviews of selected teachers to check their responses to the questionnaire and to determine their normal teaching methods, an experiment was organised in which parallel groups were given H, I and V type teaching in the normal school situation during most of one academic year. Using pre-test and post-test scores on a specially developed test of pupil understanding of the philosophy of science, it was shown that pupils were positively affected by their teacher's implied philosophy of science. There was also some indication that V type teaching improved marks obtained in school science examinations, but appeared to discourage the more able from continuing the study of science. Effects were also noted on vocabulary used by pupils to describe scientists and their activities.

The role of texture in shape from shading: are humans biased towards seeing relief textures?

When a textured surface is modulated in depth and illuminated, the level of illumination varies across the surface, producing coarse-scale luminance modulations (LM) and amplitude modulation (AM) of the fine-scale texture. If the surface has an albedo texture (reflectance variation) then the LM and AM components are always in-phase, but if the surface has a relief texture the phase relation between LM and AM varies with the direction and nature of the illuminant. We showed observers sinusoidal luminance and amplitude modulations of a binary noise texture, in various phase relationships, in a paired-comparisons design. In the first experiment, the combinations under test were presented in different temporal intervals. Observers indicated which interval contained the more depthy stimulus. LM and AM in-phase were seen as more depthy than LM alone which was in turn more depthy than LM and AM in anti-phase, but the differences were weak. In the second experiment the combinations under test were presented in a single interval on opposite obliques of a plaid pattern. Observers were asked to indicate the more depthy oblique. Observers produced the same depth rankings as before, but now the effects were more robust and significant. Intermediate LM/AM phase relationships were also tested: phase differences less than 90 deg were seen as more depthy than LM-only, while those greater than 90 deg were seen as less depthy. We conjecture that the visual system construes phase offsets between LM and AM as indicating relief texture and thus perceives these combinations as depthy even when their phase relationship is other than zero. However, when different LM/AM pairs are combined in a plaid, the signals on the obliques are unlikely to indicate corrugations of the same texture, and in this case the out-of-phase pairing is seen as flat. [Supported by the Engineering and Physical Sciences Research Council (EPSRC)].

The genius of Erasmus Darwin

The Genius of Erasmus Darwin provides insight into the full extent of Erasmus Darwin's exceptional intellect. He is shown to be a major creative thinker and innovator, one of the minds behind the late eighteenth-century industrial revolution, and one of the first, if not the first, to perceive the living world (including humans) as part of a unified evolutionary scenario. The contributions here provide contextual understandings of Erasmus Darwin's thought, as well as studies of particular works and accounts of the later reception of his writings. In this way it is possible to see why the young Samuel Taylor Coleridge was moved to describe Darwin as 'the first literary character in Europe, and the most original-minded man'. Erasmus Darwin, Charles Darwin's grandfather, was one of the leading intellectuals of eighteenth-century England. He was a man with an extraordinary range of interests and activities: he was a doctor, biologist, inventor, poet, linguist, and botanist. He was also a founding member of the Lunar Society, an intellectual community that included such eminent men as James Watt and Josiah Wedgwood. Contents: Introduction; Setting the scene, Jonathan Powers; Prologue 'Catching up with Erasmus Darwin in the New Century', Desmond King-Hele. Section 1: Medicine: Physicians and physic in 17th and 18th century Lichfield, Dennis Gibbs; Dr Erasmus Darwin MD FRS (1731–1802): England's greatest physician?, Gordon Cook; William Pale (1743–1805) and James Parkinson (1755–1824): two peri-Erasmatic thinkers (and several others), Christopher Gardner-Thorpe; The vertiginous philosophers: Erasmus Darwin and William Charles Wells on vertigo, Nicholas Wade. Section 2: Biology: The Antipodes and Erasmus Darwin: the place of Erasmus Darwin in the heritage of Australian literature and biology, John Pearn; Erasmus Darwin on human reproductive generation: placing heredity within historical and Zoonomian contexts, Philip Wilson; All from fibres: Erasmus Darwin's evolutionary psychobiology, C.U.M. Smith; Two special doctors: Erasmus Darwin and Luigi Galvani, Rafaella Simili. Section 3: Education: But what about the women? The lunar society's attitude to women and science and to the education of girls, Jenny Uglow; The Derbyshire 'Darwinians': the persistence of Erasmus Darwin's influence on a British provincial literary and scientific community, c.1780–1850, Paul Elliot. Section 4: Technology: Designing better steering for carriages (and cars); with a glance at other inventions, Desmond King-Hele; Mama and papa: the ancestors of modern-day speech science, Philip Jackson; Negative and positive images: Erasmus Darwin, Tom Wedgwood and the origins of photography, Alan Barnes; Section 5: Environment: Erasmus Darwin's contributions to the geological sciences, Hugh Torrens; The air man, Desmond King-Hele; Erasmus Darwin, work and health, Tim Carter; Section 6: Literature: The progress of society: Darwin's early drafts for the temple of nature, Martin Priestman; The poet as pathologist: myth and medicine in Erasmus Darwin's epic poetry, Stuart Harris; 'Another and the same': nature and human beings in Erasmus Darwin's doctrines of love and imagination, Maurizio Valsania. Epilogue: 'One great slaughter-house the warring world': living in revolutionary times, David Knight; Coda: Midlands memorabilia, Nick Redman; Appendix: The Creation of the Erasmus Darwin Foundation and Erasmus Darwin House, Tony Barnard; Index.

The manufacture and utilisation of architectural terracotta and faience.

The revival of terracotta and faience in British architecture was widespread, dramatic in its results and, for two decades, the subject of intense debate. However the materials have been frequently denigrated and more generally disregarded by both architects and historians. This study sets out to record and explain the rise and fall of interest in terracotta and faience, the extent and nature of the industry and the range of architectural usage in the Victorian, Edwardian and inter-war periods. The first two chapters record the faltering use of terracotta as an 'artificial stone', until the material gained its own identity, largely through the appreciation of Italian architecture. In the mid-Victorian period, terracotta will be seen to have become symbolic of the philosophy of the Victoria and Albert Museum and its Art School in attempting to reform both architecture and the decorative arts. The adoption of terracotta was furthered as much by industrial as aesthetic factors; three chapters examine how the exploitation of coal-measure clays, developments in the processes of manufacture, the changing motivation of industrialists and differing economics of production served to promote and then to hinder expansion and adaptation. The practical values of economy, durability and fire-resistance and the aesthetic potential, seen in terms of colour and decorative and sculptural modelling, became inter-related in the work of the architects who made extensive use of architectural ceramics. A correlation emerges between the free Gothic style, exemplified by the designs of Alfred Waterhouse and the use of red terracotta supplied from Ruabon, and between the eclectic Renaissance style and a buff material produced by different manufacturers.These patterns were modified as a result of the adoption of faience for facing external walls as well as interiors, and because of the new architectural requirements and tastes of the twentieth century. The general timidity in exploiting the scope for polychromatic decoration and the increasing opposition to architectural ceramics is contrasted with the most successful schemes produced for cinemas, chain-stores and factories. In the last chapter, those undertaken by the Hathern Station Brick and Terracotta Company between 1896 and 1939 are used as a case study; they confirm that manufacturers, architects and clients were all committed to creating a modern and yet decorative architecture, appropriate for new building types and that would appeal to and be comprehensible to the public.