Broad-band polarization conversion from a finite periodic structure in the microwave regime

Copyright © 2004 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Applied Physics Letters 84 (2004) and may be found at http://link.aip.org/link/?APPLAB/84/849/1A reflection grating demonstrating extraordinarily broad-band polarization conversion in a nondiffractive regime has been studied at microwave frequencies. This single-element structure has been fabricated by electrolessly plating a metallic layer onto a stereo-lithographically produced resin profile. Angle-dependent microwave reflectivity data collected from the grating indicates polarization conversion of greater than 80% over a spectral bandwidth equivalent to the entire visible regime (factor of 2 in frequency). This supports an earlier publication in which it was predicted that a broad-band polarization converter could be created from a suitably profiled diffraction grating

A robot trace maker: modeling the fossil evidence of early invertebrate behavior.

The study of trace fossils, the fossilized remains of animal behavior, reveals interesting parallels with recent research in behavior-based robotics. This article reports robot simulations of the meandering foraging trails left by early invertebrates that demonstrate that such trails can be generated by mechanisms similar to those used for robot wall-following. We conclude with the suggestion that the capacity for intelligent behavior shown by many behavior-based robots is similar to that of animals of the late Precambrian and early Cambrian periods approximately 530 to 565 million years ago

Exploring the psychological rewards of a familiar semirural landscape: connecting to local nature through a mindful approach

This study analyses a 53,000 word diary of a year engaging with nature through over 200 trips to a semi-rural landscape. Thematic analysis revealed two themes; the transition from observer to nature connectedness and the ways in which the natural environment was experienced once a connection was made. These themes are discussed in relation to theories that seek to explain the positive effect of nature and nature connectedness. The findings are important as they suggest that repeated engagement with local semi-rural countryside can lead to a mindful approach and psychological rewards that do not require travel into the wilderness. The work informs further research into outcomes and processes of nature based interventions such as: trip frequency, duration and diary keeping

In-beam internal conversion electron spectroscopy with the SPICE detector

The SPectrometer for Internal Conversion Electrons (SPICE) has been commissioned for use in conjunction with the TIGRESS $\gamma$-ray spectrometer at TRIUMF's ISAC-II facility. SPICE features a permanent rare-earth magnetic lens to collect and direct internal conversion electrons emitted from nuclear reactions to a thick, highly segmented, lithium-drifted silicon detector. This arrangement, combined with TIGRESS, enables in-beam $\gamma$-ray and internal conversion electron spectroscopy to be performed with stable and radioactive ion beams. Technical aspects of the device, capabilities, and initial performance are presented

Optically guided mode study of nematic liquid crystal alignment on a zero-order grating

B. T. Hallam and J. Roy Sambles, Physical Review E, Vol. 61, pp. 6699-6704 (2000). "Copyright © 2000 by the American Physical Society."The characterization of a liquid crystal cell, which comprises one zero-order (that is, at the wavelength of study it is nondiffractive) diffraction grating and one rubbed polyimide-coated substrate, has been performed using an optically guided mode technique. The cell is filled with nematic liquid crystal E7 (manufactured and sold by Merck, Poole, U.K.). The excitation of fully leaky guided modes within the liquid crystal layer has allowed the optical director profile to be quantified under the application of weak in-plane electric fields. The fitting of angle-dependent optical data to multilayer optical theory yields the accurate twist profile of the liquid crystal for different field strengths. Comparisons with profiles predicted from elastic continuum theory, assuming a Rapini-Papoular-type anchoring at the surfaces, allow both the azimuthal anchoring strength at each surface and the twist elastic constant of the bulk to be accurately determined. Repeating these measurements as a function of temperature allows the surface and bulk order parameters of the grating-aligned liquid crystal to be deduced

James Hutton’s geological tours of Scotland : romanticism, literary strategies, and the scientific quest

This article explores a somewhat neglected part of the story of the emergence of geology as a science and discourse in the late eighteenth century – James Hutton’s posthumously published accounts of the geological tours of Scotland that he undertook in the years 1785 to 1788 in search of empirical evidence in support of his theory of the Earth and that he intended to include in the projected third volume of his Theory of the Earth of 1795. The article brings some of the assumptions and techniques of literary criticism to bear on Hutton’s scientific travel writing in order to open up new connections between geology, Romantic aesthetics and eighteenth-century travel writing about Scotland. Close analysis of Hutton’s accounts of his field trips to Glen Tilt, Galloway and Arran, supplemented by later accounts of the discoveries at Jedburgh and Siccar Point, reveals the interplay between desire, travel and the scientific quest and foregrounds the textual strategies that Hutton uses to persuade his readers that they share in the experience of geological discovery and interpretation as ‘virtual witnesses’. As well as allowing us to revisit the interrelation between scientific theory and discovery, this article concludes that Hutton was a much better writer than he has been given credit for and suggests that if these geological tours had been published in 1795 they would have made it impossible for critics to dismiss him as an armchair geologist

To what extent is behaviour a problem in English schools?:Exploring the scale and prevalence of deficits in classroom climate

The working atmosphere in the classroom is an important variable in the process of education in schools, with several studies suggesting that classroom climate is an important influence on pupil attainment. There are wide differences in the extent to which classroom climate is considered to be a problem in English schools. Some ‘official’ reports suggest that behaviour in schools is ‘satisfactory or better’ in the vast majority of schools; other sources have pointed to behaviour being a serious and widespread problem. The paper details four studies conducted over the past decade which aimed to explore these disparities. The aim of the research was to gain a more accurate insight into the extent to which deficits in classroom climate limit educational attainment and equality of educational opportunity in English schools. The findings question the suggestion that behaviour is satisfactory or better in 99.7% of English schools and the concluding section suggests ways in which deficits in classroom climate might be addressed. Although the study is limited to classrooms in England, OECD studies suggest that deficits in the working atmosphere in classrooms occur in many countries. The study therefore has potential relevance for education systems in other countries