Functional neuroimaging and behavioural studies on global form processing in the human visual system

Magnetoencephalography (MEG), functional magnetic resonance imaging (fMRI) and behavioural experiments were used to investigate the neural processes underlying global form perception in human vision. Behavioural studies using Glass patterns examined sensitivity for detecting radial, rotational and horizontal structure. Neuroimaging experiments using either Glass patterns or arrays of Gabor patches determined the spatio-temporal neural responseto global form. MEG data were analysed using synthetic aperture magnetometry (SAM) to spatially map event-related cortical oscillatory power changes: the temporal sequencing of activity within a discrete cortical area was determined using a Morlet wavelet transform. A case study was conducted to determine the effects of strbismic amblyopia on global form processing: all other observers were normally-sighted. The main findings from normally-sighted observers were: 1) sensitivity to horizontal structure was less than for radial or rotational structure; 2) the neural response to global structure was a reduction in cortical oscillatory power (10-30 Hz) within a network of extrastriate areas, including V4 and V3a; 3) the extend of reduced cortical power was least for horizontal patters; 4) V1 was not identified as a region of peak activity with either MEG or fMRI. The main findings with the strabismic amblyope were: 1) sensitivity for detection of radial, rotational, and horizontal structure was reduced when viewed with the amblyopic- relative to the fellow- eye; 2) cortical power changes within V4 to the presentation of rotational Glass patterns were less when viewed with the amblyopic- compared with the fellow- eye. The main conclusions are: 1) a network of extrastriate cortical areas are involved in the analysis of global form, with the most prominent change in neural activity being a reduction in oscillatory power within the 10-30 Hz band; 2) in strabismic amblyopia, the neuronal assembly associated with form perception in extrastriate cortex may be dysfunctional, the nature of this dysfunction may be a change in the normal temporal pattern of neuronal discharges; 3) MEG, fMRI and behavioural measures support the notion that different neural processes underlie the perception of horizontal as opposed to radial or rotational structure.

The development of calibration and adaptive filtering procedures for neuromagnetic studies of human visual function

This thesis first considers the calibration and signal processing requirements of a neuromagnetometer for the measurement of human visual function. Gradiometer calibration using straight wire grids is examined and optimal grid configurations determined, given realistic constructional tolerances. Simulations show that for gradiometer balance of 1:104 and wire spacing error of 0.25mm the achievable calibration accuracy of gain is 0.3%, of position is 0.3mm and of orientation is 0.6°. Practical results with a 19-channel 2nd-order gradiometer based system exceed this performance. The real-time application of adaptive reference noise cancellation filtering to running-average evoked response data is examined. In the steady state, the filter can be assumed to be driven by a non-stationary step input arising at epoch boundaries. Based on empirical measures of this driving step an optimal progression for the filter time constant is proposed which improves upon fixed time constant filter performance. The incorporation of the time-derivatives of the reference channels was found to improve the performance of the adaptive filtering algorithm by 15-20% for unaveraged data, falling to 5% with averaging. The thesis concludes with a neuromagnetic investigation of evoked cortical responses to chromatic and luminance grating stimuli. The global magnetic field power of evoked responses to the onset of sinusoidal gratings was shown to have distinct chromatic and luminance sensitive components. Analysis of the results, using a single equivalent current dipole model, shows that these components arise from activity within two distinct cortical locations. Co-registration of the resulting current source localisations with MRI shows a chromatically responsive area lying along the midline within the calcarine fissure, possibly extending onto the lingual and cuneal gyri. It is postulated that this area is the human homologue of the primate cortical area V4.

Electrophysiological studies of the visual pathways in Alzheimer's and Parkinson's disease

It is known that parallel pathways exist within the visual system. These have been described as magnocellular and parvocellular as a result of the layered organisation of the lateral geniculate nucleus and extend from the retina to the cortex. Dopamine (DA) and acetylcholine (ACH) are neurotransmitters that are present in the visual pathway. DA is present in the retina and is associated with the interplexiform cells and horizontal cells. ACH is also present in the retina and is associated with displaced amacrine cells; it is also present in the superior colliculus. DA is found to be significantly depleted in the brain of Parkinson's disease (PD) patients and ACH in Alzheimer's disease (AD) patients. For this reason these diseases were used to assess the function of DA and ACH in the electrophysiology of the visual pathway. Experiments were conducted on young normals to design stimuli that would preferentially activate the magnocellular or parvocellular pathway. These stimuli were then used to evoke visual evoked potentials (VEP) in patients with PD and AD, in order to assess the function of DA and ACH in the visual pathway. Electroretinograms (ERGs) were also measured in PD patients to assess the role of DA in the retina. In addition, peripheral ACH function was assessed by measuring VEPs, ERGs and contrast sensitivity (CS) in young normals following the topical instillation of hyoscine hydrobromide (an anticholinergic drug). The results indicate that the magnocellular pathway can be divided into two: a cholinergic tectal-association area pathway carrying luminance information, and a non-cholinergic geniculo-cortical pathway carrying spatial information. It was also found that depletion of DA had very little effect on the VEPs or ERGs, confirming a general regulatory function for this neurotransmitter.

Topographic studies of scalp potentials evoked by pattern presentation

The waveform and scalp distribution of the visual evoked potentials elicited by stimuli in the foveal and parafoveal regions have been investigated in a group of normal humans using a 16-channel `brain mapping' system. The waveform and topography of the responses to pattern onset and pattern reversal stimulation were investigated, using 4 x 4o full field and 4 x 2o lateral and altitudinal half-field stimuli. The responses were composed of several successive peaks which are in some respects consistent with those demonstrated by other workers using larger field sizes. The differences in the behaviour of these components with respect to the position of the stimulus in the visual field were suggestive of origins in different areas of the visual cortex and/or different visual mechanism. Of particular interest were the major early positive components `P90' and `P95' of the responses to pattern onset and pattern reversal stimulation respectively. More detailed exploration of the behaviour of these major early positive components was carried out using `M-scaled' stimuli selected to activate one square centimetre patches of striate cortex and associated extrastriate re-projections, positioned at different points in the foveal and parafoveal area of the visual field. The inter- and intra-subject variability in amplitude and localisation of the signals elicited by these targets was considered to be a reflection of the individual variations in relationship of visual field projections with the pattern of gyri and fissures on the proximal surface of the occipital lobe. The behaviour of component P90 of the onset response is consistent with a lateral origin in extrastriate visual cortex; that of P95 of the pattern reversal response is consistent in some respects with a striate cortical origin, but in others with a partial origin in extrastriate cortex.

Fibre optic sensors for high speed hypervelocity impact studies and low velocity drop tests

The initial aim of this project was to develop a non-contact fibre optic based displacement sensor to operate in the harsh environment of a 'Light Gas Gun' (LGG), which can 'fire' small particles at velocities ranging from 1-8.4 km/s. The LGG is used extensively for research in aerospace to analyze the effects of high speed impacts on materials. Ideally the measurement should be made close to the centre of the impact to minimise corruption of the data from edge effects and survive the impact. A further requirement is that it should operate at a stand-off distance of ~ 8cm. For these reasons we chose to develop a pseudo con-focal intensity sensor, which demonstrated resolution comparable with conventional PVDF sensors combined with high survivability and low cost. A second sensor was developed based on 'Fibre Bragg Gratings' (FBG) which although requiring contact with the target the low weight and very small contact area had minimal effect on the dynamics of the target. The FBG was mounted either on the surface of the target or tangentially between a fixed location. The output signals from the FBG were interrogated in time by a new method. Measurements were made on composite and aluminium plates in the LGG and on low speed drop tests. The particle momentum for the drop tests was chosen to be similar to that of the particles used in the LGG.

Doctoral work in translation studies as an interdisciplinary mutual learning process:how a translator, teacher educator and linguistic typologist worked together

The focus of this paper is on the doctoral research training experienced by one of the authors and the ways in which the diverse linguistic and disciplinary perspectives of her two supervisors (co-authors of this paper) mediated the completion of her study. The doctoral candidate is a professional translator/interpreter and translation teacher. The paper describes why and how she identified her research area and then focused on the major research questions in collaboration with her two supervisors, who brought their differing perspectives from the field of linguistics to this translation research, even though they are not translators by profession or disciplinary background and do not speak Korean. In addition, the discussion considers the focus, purpose and theoretical orientation of the research itself (which addressed questions of readability in translated English-Korean texts through detailed analysis of a corpus and implications for professional translator training) as well as the supervisory and conceptual processes and practices involved. The authors contend that doctoral research of this kind can be seen as a mutual learning process and that inter-disciplinary research can make a contribution not only to the development of rigorous research in the field of translation studies but also to the other disciplinary fields involved.

Empirical studies of corporate governance in China

The thesis aims to provide empirical studies towards Chinese corporate governance. Since China initially established its stock exchange system in the 1990s, it has gone through different stages of changes to become a more market-oriented system. Extensive studies have been conducted in Chinese corporate governance, however, many were theoretical discussion focusing on the early stages and there‘s a general lack of empirical analysis. This paper provides three empirical analysis of the Chinese corporate governance: the overall market discipline efficiency, the impact of capital structure on agency costs, the status of 2005- 2006 reform that substantially modified ownership structure of Chinese listed firms and separated ownership and control of listed firms. The three empirical studies were selected to reflect four key issues that need answering: the first empirical study, using event study to detect market discipline on a collective level. This study filled a gap in the Chinese stock market literature for being the first one ever using cross-market data to test market discipline. The second empirical study endeavoured to contribute to the existing corporate governance literature regarding capital structure and agency costs. Two conclusions can be made through this study: 1) for Chinese listed firms, higher gearing means higher asset turnover ratios and ROE, i.e. more debts seem to reduce agency costs; 2) concentration level of shares appears to be irrelevant with company performance, controlling shareholders didn‘t seem to commit to the improvement of corporate assets utilization or contribute to reducing agency costs. This study addressed a key issue in Chinese corporate governance since the state has significant shareholding in most big listed companies. The discussion of corporate governance in the Chinese context would be completely meaningless without discussing the state‘s role in corporate governance, given that about 2/3 of the almost all shares were non-circulating shares controlled by the state before the 2005-2006 overhaul ownership reform. The third study focused on the 2005-2006 reform of ownership of Chinese listed firms. By collecting large-scale data covering all 64 groups of Chinese listed companies went through the reform by the end of 2006 (accounting for about 97.86% and 96.76% of the total market value of Shanghai (SSE) and Shenzhen Stock Exchange (SZSE) respectively), a comprehensive study about the ownership reform was conducted. This would be first and most comprehensive empirical study in this area. The study of separated ownership and control of listed firm is the first study conducted using the ultimate ownership concept in Chinese context.

Sub-national responses to climate change in England:evidence from local area agreements

The machinery of governance to address climate change at the sub-national level in England continues to evolve. Drawing on documentary evidence and the views of civil servants and local authority officials from the English West Midlands, this article explores the process through an examination of the inclusion of climate change indicators in the recent round of Local Area Agreements (LAAs), negotiated between central government and local authorities and Local Strategic Partnerships. Considerable popularity has been accorded these indicators nationally, but there are important variations in the pattern of take up. Moreover, significant uncertainties surround the contribution of local measures to reduce CO2 emissions and the targets attached to measures to adapt to climate change are seen as undemanding. Conversely, the impending Carbon Reduction Commitment will act as a powerful incentive for public bodies to cut CO2 emissions from their estates. Although potentially contributing to greater coherence in tackling climate change, achieving collective action through LAAs will prove problematic.

SME resilience to extreme weather events:important initiatives for informing policy making in the area

Enhancing the resilience of local communities to weather extremes has gained significant interest over the years, amidst the increased intensity and frequency of such events. The fact that such weather extremes are forecast to further increase in number and severity in future has added extra weight to the importance of the issue. As a local community consists of a number of community groups such as households, businesses and policy makers, the actions of different community groups in combination will determine the resilience of the community as a whole. An important role has to be played by Small and Medium-sized Enterprises (SMEs); which is an integral segment of a local community in the UK, in this regard. While it is recognised that they are vital to the economy of a country and determines the prosperity of communities, they are increasingly vulnerable to effects of extreme weather. This paper discusses some of the exploratory studies conducted in the UK on SMEs and their ability to cope with extreme weather events, specifically flooding. Although a reasonable level of awareness of the risk was observed among the SMEs, this has not always resulted in increased preparedness even if they are located in areas at risk of flooding. The attitude and the motivation to change differed widely between SMEs. The paper presents schemas by which the SMEs can identify their vulnerability better so that they can be populated among a community of SMEs, which can be taken forward to inform policy making in this area. Therefore the main contribution the paper makes to the body of knowledge in the area is a novel way to communicate to SMEs on improving resilience against extreme weather, which will inform some of the policy making initiatives in the UK.

Fibre optic sensors for high speed hypervelocity impact studies and low velocity drop tests

The initial aim of this project was to develop a non-contact fibre optic based displacement sensor to operate in the harsh environment of a 'Light Gas Gun' (LGG), which can 'fire' small particles at velocities ranging from 1-8.4 km/s. The LGG is used extensively for research in aerospace to analyze the effects of high speed impacts on materials. Ideally the measurement should be made close to the centre of the impact to minimise corruption of the data from edge effects and survive the impact. A further requirement is that it should operate at a stand-off distance of ~ 8cm. For these reasons we chose to develop a pseudo con-focal intensity sensor, which demonstrated resolution comparable with conventional PVDF sensors combined with high survivability and low cost. A second sensor was developed based on 'Fibre Bragg Gratings' (FBG) which although requiring contact with the target the low weight and very small contact area had minimal effect on the dynamics of the target. The FBG was mounted either on the surface of the target or tangentially between a fixed location. The output signals from the FBG were interrogated in time by a new method. Measurements were made on composite and aluminium plates in the LGG and on low speed drop tests. The particle momentum for the drop tests was chosen to be similar to that of the particles used in the LGG.

Fourth-root summation of contrast over area:no end in sight when spatially inhomogeneous sensitivity is compensated by a witch's hat

Measurements of area summation for luminance-modulated stimuli are typically confounded by variations in sensitivity across the retina. Recently we conducted a detailed analysis of sensitivity across the visual field (Baldwin et al, 2012) and found it to be well-described by a bilinear “witch’s hat” function: sensitivity declines rapidly over the first 8 cycles or so, more gently thereafter. Here we multiplied luminance-modulated stimuli (4 c/deg gratings and “Swiss cheeses”) by the inverse of the witch’s hat function to compensate for the inhomogeneity. This revealed summation functions that were straight lines (on double log axes) with a slope of -1/4 extending to ≥33 cycles, demonstrating fourth-root summation of contrast over a wider area than has previously been reported for the central retina. Fourth-root summation is typically attributed to probability summation, but recent studies have rejected that interpretation in favour of a noisy energy model that performs local square-law transduction of the signal, adds noise at each location of the target and then sums over signal area. Modelling shows our results to be consistent with a wide field application of such a contrast integrator. We reject a probability summation model, a quadratic model and a matched template model of our results under the assumptions of signal detection theory. We also reject the high threshold theory of contrast detection under the assumption of probability summation over area.

Strategies for sustaining manufacturing competitiveness:comparative case studies in Australia and Sweden

Purpose - The purpose of this paper is to report an investigation of local sustainable production in Australia and Sweden aimed at exploring the factors contributing to survival and competitiveness of manufacturing companies. Design/methodology/approach - In Australia, six companies were studied in 2010, with comparisons being made with three of them from earlier projects. In Sweden, eight manufacturing companies were studied on two occasions 30 years apart, in 1980 and 2010. To provide a valid comparative perspective a common format for data collection and analysis was used. Findings - There has been a shift in the nature of competition in both Sweden and Australia due to an increasing complexity of the global business environment as well as changes in technology and customer expectations. Despite the differences in country context, the findings suggest that all the manufacturing companies have a good awareness of the elements of the market environment and the relationships with their competitive strategy. However, in general, the Swedish companies have more experience of managing the risks and benefits from operating in the international environment. Research limitations/implications - The results of the research are based on a relatively small sample of case companies in a limited number of industrial sectors. There are methodology implications for future research in the area. Practical implications - The research results have practical implications for the manufacturing industry, especially for companies operating in a competitive international environment. Originality/value - The paper is based on original case research and comparative analysis of data from different geographical contexts. It contributes to both theory and management practice about the strategic resources, decision choices, competitive environments and firm values needed to address external market demands as well as in building internal capabilities.

Catalyst studies on the ring opening of tetrahydrofuran-dimethanol to 1,2,6-hexanetriol

The metal catalyzed hydrogenolysis of the biomass-derived THF-dimethanol to 1,2,6-hexanetriol using heterogeneous catalysts was investigated. Bimetallic Rh-Re catalysts (4 wt% Rh and a Re/Rh (mol. ratio of 0.5) on a silica support gave the best performance and 1,2,6-hexanetriol was obtained in 84% selectivity at 31% conversion (120 C, 80 bar, 4 h); the selectivity reaches a maximum of 92% at 80 C. The product distribution at prolonged reaction times or higher temperatures or both shows the formation of diols and mono-alcohols, indicating that the 1,2,6-hexanetriol is prone to subsequent hydrodeoxygenation reactions. Different silica supports were investigated and optimal results were obtained with an amorphous silica featuring an intermediate surface area and an average mesopore size of about 6 nm. TPR and XPS surface analysis support the presence of mixed Rh and Re particles. The redox Reδ+/ReTotal surface ratio correlates with the conversion in a volcano type dependency. Both gas phase as well as Rh200Re1OH cluster DFT calculations support an acid-metal bifunctional mechanism and explain the products distribution. © 2013 Elsevier B.V. All rights reserved.

Zoocoenological state of microhabitats and its seasonal dynamics in an aquatic macroinvertebrate assembly (Hydrobiological case studies on lake Balaton, No. 1.)

In the years 2002, 2003 and 2004 we collected samples of macroinvertebrates on a total of 36 occasions in Badacsony bay, in areas of open water (in the years 2003 and 2004 reed-grassy) as well as populated by reed (Phragmites australis) and cattail (Typha angustifolia). Samples were taken using a stiff hand net. The sampling site includes three microhabitats differentiated only by the aquatic plants inhabiting these areas. Our data was gathered from processing 208 individual samples. The quantity of macroinvertebrates is represented by biovolume value based on volume estimates. We can identify taxa in abundant numbers found in all water types and ooze; as well as groups associated with individual microhabitats with various aquatic plants. We can observe a notable difference between the years in the volume of invertebrate macrofauna caused by the drop of water level, and the multiplication of submerged macrophytes. There are smaller differences between the samples taken in reeds and cattail stands. In the second half of 2003 – which was a year of drought – the Najas marina appeared in open waters and allowed to support larger quantities of macroinvertebrates. In 2004 with higher water levels, the Potamogeton perfoliatus occurring in the same area has had an even more significant effect. This type of reed-grass may support the most macroinvertebrates during the summer. From the aspect of diversity relations we may suspect different characteristics. The reeds sampling site proved to be the richest, while the cattail microhabitat is close behind, open water (with submerged macrophytes) is the least diverse microhabitat.

International education and the post-9/11 syndrome: A study of international educators in selected Miami-area colleges

This dissertation investigated the relationship between the September 11, 2001 terrorist attacks and the internationalization agenda of U.S. colleges and universities. The construct, post-9/11 syndrome, is used metaphorically to delineate the apparent state of panic and disequilibrium that followed the incident. Three research questions were investigated, with two universities in the Miami-area of South Florida, one private and the other public, as qualitative case studies. The questions are: (a) How are international student advisors and administrators across two types of institutions dealing with the post-9/11 syndrome? (b) What, if any, are the differences in international education after 9/11? (c) What have been the institutional priorities in relation to international education before and after 9/11? Data-gathering methods included interviews with international student/study abroad advisors and administrators with at least 8 years of experience in the function(s) at their institutions, document and institutional data analysis. The interviews were based on the three-part scheme developed by Schuman (1982): context of experience, details of experience and reflection on the meaning of experiences. Taped interviews, researcher insights, and member checks of transcripts constituted an audit trail for this study. Key findings included a progressive decline in Fall to Fall enrollment of international students at UM by 13.05% in the 5 years after 9/11, and by 6.15% at FIU in the seven post-9/11 years. In both institutions, there was an upsurge in interest in study abroad during the same period but less than 5% of enrolled students ventured abroad annually. I summarized the themes associated with the post-9/11 environment of international education as perceived by my participants at both institutions as 3Ms, 3Ts, and 1D: Menace of Anxiety and Fear, Menace of Insularity and Insecurity, Menace of Over-Regulation and Bigotry, Trajectory of Opportunity, Trajectory of Contradictions, Trajectory of Illusion, Fatalism and Futility, and Dominance of Technology. Based on these findings, I recommended an integrated Internationalization At Home Plus Collaborative Outreach (IAHPCO) approach to internationalization that is based on a post-9/11 recalibration of national security and international education as complementary rather than diametrically opposed concepts.