The asymmetries of colour constancy as determined through illumination discrimination using tuneable LED light sources

PhD ThesisThe light reflected from object surfaces changes with the spectral content of the illumination. Despite these changes, the human visual system tends to keep the colours of surfaces constant, a phenomenon known as colour constancy. Colour constancy is known to be imperfect under many conditions; however, it is unknown whether the underlying mechanisms present in the retina and the cortex are optimised for the illuminations under which they have evolved, namely, natural daylights, or for particular objects. A novel method of measuring colour constancy, by illumination discrimination, is presented and explored. This method, unlike previous methods of measuring colour constancy, allows the testing of multiple, real, illuminations with arbitrary spectral content, through the application of tuneable, multi-channel LED light sources. Data from both real scenes, under real illuminations, and computer simulations are presented which support the hypothesis that the visual system maintains higher levels of colour constancy for daylight illumination changes, and in particular in the “bluer” direction, which are also the changes most frequent in nature. The low-level cone inputs for various experimental scenes are examined which challenge all traditional theories of colour constancy supporting the conclusions that higher-level mechanisms of colour constancy are biased for particular illuminations. Furthermore, real and simulated neutral (grey) surfaces are shown to affect levels of colour constancy. Moreover, the conceptual framework for discussing colour constancy with respect to emergent LED light sources is discussed.EPSR

Toward a user-oriented analytical approach to learning design

The London Pedagogy Planner (LPP) is a prototype for a collaborative online planning and design tool that supports lecturers in developing, analysing and sharing learning designs. The tool is based on a developing model of the components involved in learning design, and the critical relationships between them. As a decision tool, it makes the pedagogical design explicit as an output from the process, capturing it for testing, redesign, reuse and adaptation by the originator, or by others. The aim is to test the extent to which we can engage lecturers in reflecting on learning design, and make them part of the educational community that discovers how best to use Technology Enhanced Learning (TEL). This paper describes the development of LPP, presents pedagogical benefits of visual representations of learning designs, and proposes an analytical approach to learning design based on these visual representations. The analytical approach is illustrated based on an initial evaluation with the lecturers

Towards a user oriented analytical approach to learning design

The London Pedagogy Planner (LPP) is a prototype for a collaborative online planning and design tool that supports lecturers in developing, analysing and sharing learning designs. The tool is based on a developing model of the components involved in learning design and the critical relationships between them. As a decision tool it makes the pedagogical design explicit as an output from the process, capturing it for testing, redesign, reuse and adaptation by the originator, or by others. The aim is to test the extent to which we can engage lecturers in reflecting on learning design, and make them part of the educational community that discovers how best to use technology‐enhanced learning. This paper describes the development of LPP, presents pedagogical benefits of visual representations of learning designs and proposes an analytical approach to learning design based on these visual representations. The analytical approach is illustrated based on an initial evaluation with a small group of lecturers from two partner institutions

Can Light Echoes Account for the Slow Decay of Type IIn Supernovae?

The spectra of type IIn supernovae indicate the presence of apre-existing slow, dense circumstellar wind (CSW). If the CSW extends sufficiently far from the progenitor star, then dust formation should occur in the wind. The light from the supernova explosion will scatter off this dust and produce a light echo. Continuum emission seen after the peak will have contributions from both this echo as well as from the shock of the ejecta colliding with the CSW, with a fundamental question of which source dominates the continuum. We calculate the brightness of the light echo as a function of time for a range of dust shell geometries, and use our calculations to fit to the light curves of SN 1988Z and SN 1997ab, the two slowest declining IIn supernovae on record. We find that the light curves of both objects can be reproduced by the echo model. However, their rate of decay from peak, color at peak and their observed peak absolute magnitudes when considered together are inconsistent with the echo model. Furthermore, when the observed values of M$_{B}$ are corrected for the effects of dust scattering, the values obtained imply that these supernovae have unrealistically high luminosities. We conclude that light echoes cannot properly account for the slow decline seen in some IIn's, and that the shock interaction is likely to dominate the continuum emission.Comment: 15 pages, 9 figure

Projecting productivity losses for cancer-related mortality 2011 - 2030

© 2016 The Author(s). Background: When individuals stop working due to cancer this represents a loss to society - the loss of productivity. The aim of this analysis was to estimate productivity losses associated with premature mortality from all adult cancers and from the 20 highest mortality adult cancers in Ireland in 2011, and project these losses until 2030. Methods: An incidence-based method was used to estimate the cost of cancer deaths between 2011 and 2030 using the Human Capital Approach. National data were used for cancer, population and economic inputs. Both paid work and unpaid household activities were included. Sensitivity analyses estimated the impact of assumptions around future cancer mortality rates, retirement ages, value of unpaid work, wage growth and discounting. Results: The 233,000 projected deaths from all invasive cancers in Ireland between 2011 and 2030 will result in lost productivity valued at €73 billion; €13 billion in paid work and €60 billion in household activities. These losses represent approximately 1.4 % of Ireland's GDP annually. The most costly cancers are lung (€14.4 billion), colorectal and breast cancer (€8.3 billion each). However, when viewed as productivity losses per cancer death, testis (€364,000 per death), cervix (€155,000 per death) and brain cancer (€136,000 per death) are most costly because they affect working age individuals. An annual 1 % reduction in mortality reduces productivity losses due to all invasive cancers by €8.5 billion over 20 years. Conclusions: Society incurs substantial losses in productivity as a result of cancer-related mortality, particularly when household production is included. These estimates provide valuable evidence to inform resource allocation decisions in cancer prevention and control

Chromatic Illumination Discrimination Ability Reveals that Human Colour Constancy Is Optimised for Blue Daylight Illuminations

The phenomenon of colour constancy in human visual perception keeps surface colours constant, despite changes in their reflected light due to changing illumination. Although colour constancy has evolved under a constrained subset of illuminations, it is unknown whether its underlying mechanisms, thought to involve multiple components from retina to cortex, are optimised for particular environmental variations. Here we demonstrate a new method for investigating colour constancy using illumination matching in real scenes which, unlike previous methods using surface matching and simulated scenes, allows testing of multiple, real illuminations. We use real scenes consisting of solid familiar or unfamiliar objects against uniform or variegated backgrounds and compare discrimination performance for typical illuminations from the daylight chromaticity locus (approximately blue-yellow) and atypical spectra from an orthogonal locus (approximately red-green, at correlated colour temperature 6700 K), all produced in real time by a 10-channel LED illuminator. We find that discrimination of illumination changes is poorer along the daylight locus than the atypical locus, and is poorest particularly for bluer illumination changes, demonstrating conversely that surface colour constancy is best for blue daylight illuminations. Illumination discrimination is also enhanced, and therefore colour constancy diminished, for uniform backgrounds, irrespective of the object type. These results are not explained by statistical properties of the scene signal changes at the retinal level. We conclude that high-level mechanisms of colour constancy are biased for the blue daylight illuminations and variegated backgrounds to which the human visual system has typically been exposed

The measurement of guanxi: Introducing the GRX scale

This is the post-print version of the final paper published in Industrial Marketing Management. The published article is available from the link below. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. Copyright @ 2010 Elsevier B.V.This study posits and examines a measurement scale for measuring guanxi based on three Chinese relational constructs – ganqing, renqing and xinren. Focusing on Anglo-Chinese buyer–seller relationships, the research reports the findings from six qualitative in-depth interviews and survey data obtained from over 200 Taiwanese trading companies. Based on exploratory and confirmatory factor analyses the findings from the final second-order confirmatory factor analysis of the guanxi model identified 11 items for measuring ganqing, renqing, xinren and guanxi respectively. The results offer a useful starting point in order for business practitioners to assess their guanxi and at the same time provide academics with a scale for operationalizing the measurement of guanxi

Pharmacology education for nurse prescribing students – a lesson in reusable learning objects

<p>Abstract</p> <p>Background</p> <p>The shift away from a biological science to a social science model of nursing care has resulted in a reduction in pharmacology knowledge and understanding in pre-registration nursing students. This has a significant impact on nurse prescribing training where pharmacology is a critical component of the course from a patient safety perspective.</p> <p>Methods</p> <p>Reusable learning objects (RLOs) are electronic resources based on a single learning objective which use high quality graphics and audio to help engagement with the material and to facilitate learning. This study used questionnaire data from three successive cohorts of nurse prescribing students (n = 84) to evaluate the use of RLOs focussed around pharmacology concepts to promote the understanding of these concepts in students. A small number of students (n = 10) were followed up by telephone interview one year after qualification to gain further insight into students' perceptions of the value of RLOs as an educational tool.</p> <p>Results</p> <p>Students' perceptions of their own understanding of pharmacology concepts increased substantially following the introduction of RLOs to supplement the pharmacology component of the course. Student evaluation of the RLOs themselves was extremely positive with a number of students continuing to access these tools post-qualification.</p> <p>Conclusion</p> <p>The use of RLOs to support the pharmacology component of nurse prescribing courses successfully resulted in a perceived increase in pharmacology understanding, with some students directly implicating these educational tools in developing confidence in their own prescribing abilities.</p