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Diffraction in volume reflection gratings with variable fringe contrast
Get PDFThe PSM model is used to analyze the process of diffraction occurring in volume reflection gratings in which fringe contrast is an arbitrary function of distance within the grating. General analytic expressions for diffraction efficiency at Bragg resonance are obtained for unslanted panchromatic lossless reflection gratings at oblique incidence. These formulas are then checked for several diverse fringe contrast profiles with numerical solutions of the Helmholtz equation, where exceptionally good agreement is observed. Away from Bragg resonance, the case of the hyperbolically decaying fringe contrast profile is shown to lead to an analytic expression for the diffraction efficiency and this is again compared successfully with numerical solutions of the Helmholtz equation
Determination of the degree of polymerisation of fructans from rye-grass and chicory using MALDI-TOF Mass Spectrometry and Gel Permeation Chromatography coupled to multiangle laser light scattering
Get PDFThis study is concerned with the determination of the degree of polymerisation (DP) of fructans from chicory and rye-grass (Lolium perenne L.) using Gel Permeation Chromatography coupled to multiangle laser light scattering and refractive index detectors (GPC / MALLS) and Matrix-Assisted Laser Desorption/Ionisation Time of Flight Mass Spectrometry (MALDI-TOF MS). The results show that fructans isolated from ryegrass have a DP in the range 2 - >100 and the commercially produced fructans derived from chicory have a DP in range 2 - 61. It has been demonstrated that MALDI-TOF MS is particularly effective at determining the DP of low molar mass material but is less effective for detecting the presence of high DP molecules. On the other hand GPC / MALLS is able to provide a much broader range of DP values although it is less sensitive at very low DP. It has been shown that the two techniques give complementary information thus providing a more accurate estimate of the overall DP of the fructan molecules
Discrete action micro-actuator optimization
Get PDFMicro-electro-mechanical systems (MEMS) devices are widely used in industry. The micro-actuator is an important component of such devices, transforming external influence into mechanical displacement. The development of a design technique to derive the optimal design parameters for a micro-actuator is a problem of current interest. The present paper describes a technique for determining geometric parameters for a simplified micro-actuator structure (a hemispherical shell), such that under a prescribed critical pressure it will undergo a specified discrete deflection. Such a deflection is commonly referred to as "snap-through". A mathematical model and a Finite Element procedure for the mechanical analysis of a flexible thin-walled shell under large deformation are proposed. Initially the snap-through is modelled as a quasi-static effect, but subsequently, the influence of the inertia is also considered. The optimization procedure was performed using the PSE/MACROS optimization program. The results for an example model numerical optimization are shown
A profile of the members of the British Humanist Association’
Get PDFIn 1967 Campbell published the first detailed survey of the members of the British Humanist Association. His survey of 931 members represented the most comprehensive study of the members of the organisation then published. The current research builds on Campbell’s work and offers a detailed profile of the membership of the British Humanist Association at the start of the 21st century. The results of a survey conducted in 2014 of 1,097 humanists are presented and compared with Campbell’s original 1967 data and against data derived from the 2011 United Kingdom Census. Particular attention is given to the topics of sex, age, residence, employment, and education background of the members
Exploring Synchronicity in the Heart Rates of Familiar and Unfamiliar Pairs of Horses and Humans Undertaking an In-Hand Task
Get PDFPhysiological responses that occur in horses and humans during their interactions, on the ground and during ridden work, have been investigated in a number of studies with some conflicting results. These suggest that in some situations emotional state may be transferred from humans to horses and that there is the potential for the heart rates of horse–human pairs to become synchronized during ridden work. Here we explore the effect of familiarity on the physiological responses of horse–human pairs completing a task in-hand, using heart rate as an indicator for emotional state. We investigated differences in heart rate response between familiar and unfamiliar pairings and the possibility of heart rate synchronization within each pair. Complete sets of horse and human heart rate data were available for 17 horses. We found a significant order affect, with higher horse heart rates seen the first time around the course regardless of whether a familiar or unfamiliar handler was leading (Wilcoxon test: Z=–2.67, p<0.05). However, despite this, the horses’ mean heart rates for each course were significantly higher with the unfamiliar handler than with the familiar handler (Wilcoxon test: Z=–4.46, p<0.001). In contrast, human heart rates were higher when paired with a familiar horse compared with an unfamiliar horse (Mann-Whitney U test: Z=–5.08, p<0.001). Significant correlations between horse and human heart rates were seen in three familiar pairings and two unfamiliar pairings. Our findings indicate that the relationship between horse and human heart rates during interactions is not straightforward or consistent between horses and humans, and is likely to depend on a number of factors such as experience of the test situation. Although the lower heart rates seen in horses being led by their familiar handler suggest that they are more relaxed with someone they know, this could not be said for the human partner
Collaborative Research in Art, Design and New Media - Challenges and Opportunities
Get PDFCollaboration between the arts and the sciences has a long history of tension and antipathy, and also, paradoxically, interdependence. Artists such as Leonardo da Vinci were involved with the creation of artistic works and also novel inventions that were intended to serve a purpose in the natural world. More recently the rapid advances of technology underpinning new media have facilitated both the collaboration of artists in virtual spaces and the use of new media to create, view, and interact with artistic works. Technology and applications are changing the way ideas are formed and the way research is developed and advanced. In addition, the ubiquity of new media has facilitated its use to support and develop a number of application domains. This paper explores the relationship between creativity, collaboration, and artistic works, and their interaction and interplay with social media
CdCl2 treatment related diffusion phenomena in Cd1xZnxS/CdTe solar cells
Get PDFUtilisation of wide bandgap Cd1_xZnxS alloys as an alternative to the CdS window layer is an attractive route to enhance the performance of CdTe thin film solar cells. For successful implementation, however, it is vital to control the composition and properties of Cd1_xZnxS through device fabrication processes involving the relatively high-temperature CdTe deposition and CdCl2 activation steps. In this study, cross-sectional scanning transmission electron microscopy and depth profiling methods were employed to investigate chemical and structural changes in CdTe/Cd1_xZnxS/CdS superstrate device structures deposited on an ITO/boro-aluminosilicate substrate. Comparison of three devices in different states of completion—fully processed (CdCl2 activated), annealed only (without CdCl2 activation), and a control (without CdCl2 activation or anneal)—revealed cation diffusion phenomena within the window layer, their effects closely coupled to the CdCl2 treatment. As a result, the initial Cd1_xZnxS/CdS bilayer structure was observed to unify into a single Cd1_xZnxS layer with an increased Cd/Zn atomic ratio; these changes defining the properties and performance of the Cd1_xZnxS/CdTe device
Aiming for outstanding: Action research from students of the MSc in the Teaching of Psychology
Get PDFThe first cohort of a new MSc programme is due to complete the course in August 2014. During the three-year online course students conduct several pieces of action research in their classrooms. There is little research specifically related classroom practice in the pre-tertiary psychology classroom. The following describes the rationale and context of the MSc in the Teaching of Psychology and reports on three students’ final year research. The first considers the benefits of Psychology Applied Learning Scenarios (PALS) as applied to an A-level Psychology lesson. This is followed by research on the academic impact the flipped classroom can have on AS and A Level progress and the perceptions of this teaching technique learners have. Finally a plenary designed to develop critical thinking skills and meet the criteria for an ‘outstanding’ lesson is discussed. Conducting action research into one’s own teaching produces reflective, self-critical practitioners and these skills are also transmitted to their own students
Advanced Abrasive Processes for Manufacturing Prototype Mirror Segments for the World’s Largest Telescope
Get PDFThis paper describes the application of loose-abrasive processes to the manufacture of 1.4 meter, off-axis aspheric, hexagonal mirror-segments. These are prototypes for the 39 m European Extremely Large Telescope (E-ELT). The application of active forces to correct the overall form of segments in the telescope, means that the overall form-accuracy achieved in polishing can be less critical than for a non-active mirror. However, it is a requirement that the base-radii and conic constants of mirror-segments are very closely matched, so that the combined image is not degraded. This means that abrasive processes have to operate with respect to an absolute rather than relative datum. Furthermore, there are stringent requirements on mid-spatial frequency defects on segment surfaces, and on edge-roll. These control stray-light, and ultimately detectability of faint astronomical targets. We describe the CNC abrasive techniques we have developed in response. We then demonstrate the success of the approach, which represents the first time ever that segments have been processed entirely in the hexagonal shape:- a milestone in loose-abrasive processing. Finally, we address up-scale for the unprecedented number of segments required for the E-ELT build-phase
Identification of crystals forming on porcine articular cartilage: a new method for the estimation of the postmortem interval
Get PDFArticular cartilage was examined to determine its decomposition sequence and its potential for assessing the postmortem interval. Scanning electron microscopy of articular cartilage from buried porcine trotters showed the presence of microcrystals on the synovial surface. These orthorhombic pyramidal or “coffin”-shaped crystals, appeared at 3 weeks (22 days) after interment and disappeared after 6 weeks. The disappearance of these crystals was linked to decompositional changes to the integrity of the synovial joint. The formation and disappearance of these crystals was associated with a pH change at the cartilage surface. Scanning electron microscopy–energy-dispersive X-ray (SEM-EDX) analysis showed that the five main elements contained within these crystals were carbon, nitrogen, oxygen, magnesium, and phosphorous. Such elemental analysis suggested the crystals may be struvite (MgNH4PO46(H2O)). Bacteria cultured from the cartilage synovial surface produced struvite crystals when grown in suitable media and were identified by DNA analysis to be Comamonas sp