The Riesz transform and simultaneous representations of phase, energy and orientation in spatial vision

To represent the local orientation and energy of a 1-D image signal, many models of early visual processing employ bandpass quadrature filters, formed by combining the original signal with its Hilbert transform. However, representations capable of estimating an image signal's 2-D phase have been largely ignored. Here, we consider 2-D phase representations using a method based upon the Riesz transform. For spatial images there exist two Riesz transformed signals and one original signal from which orientation, phase and energy may be represented as a vector in 3-D signal space. We show that these image properties may be represented by a Singular Value Decomposition (SVD) of the higher-order derivatives of the original and the Riesz transformed signals. We further show that the expected responses of even and odd symmetric filters from the Riesz transform may be represented by a single signal autocorrelation function, which is beneficial in simplifying Bayesian computations for spatial orientation. Importantly, the Riesz transform allows one to weight linearly across orientation using both symmetric and asymmetric filters to account for some perceptual phase distortions observed in image signals - notably one's perception of edge structure within plaid patterns whose component gratings are either equal or unequal in contrast. Finally, exploiting the benefits that arise from the Riesz definition of local energy as a scalar quantity, we demonstrate the utility of Riesz signal representations in estimating the spatial orientation of second-order image signals. We conclude that the Riesz transform may be employed as a general tool for 2-D visual pattern recognition by its virtue of representing phase, orientation and energy as orthogonal signal quantities.

Spatially extensive summation of contrast-energy is revealed by contrast detection of micro-pattern textures

Vision must analyze the retinal image over both small and large areas to represent fine-scale spatial details and extensive textures. The long-range neuronal convergence that this implies might lead us to expect that contrast sensitivity should improve markedly with the contrast area of the image. But this is at odds with the orthodox view that contrast sensitivity is determined merely by probability summation over local independent detectors. To address this puzzle, I aimed to assess the summation of luminance contrast without the confounding influence of area-dependent internal noise. I measured contrast detection thresholds for novel Battenberg stimuli that had identical overall dimensions (to clamp the aggregation of noise) but were constructed from either dense or sparse arrays of micro-patterns. The results unveiled a three-stage visual hierarchy of contrast summation involving (i) spatial filtering, (ii) long-range summation of coherent textures, and (iii) pooling across orthogonal textures. Linear summation over local energy detectors was spatially extensive (as much as 16 cycles) at Stage 2, but the resulting model is also consistent with earlier classical results of contrast summation (J. G. Robson & N. Graham, 1981), where co-aggregation of internal noise has obscured these long-range interactions.

Edges and bars: where do people see features in 1-D images?

There have been two main approaches to feature detection in human and computer vision - based either on the luminance distribution and its spatial derivatives, or on the spatial distribution of local contrast energy. Thus, bars and edges might arise from peaks of luminance and luminance gradient respectively, or bars and edges might be found at peaks of local energy, where local phases are aligned across spatial frequency. This basic issue of definition is important because it guides more detailed models and interpretations of early vision. Which approach better describes the perceived positions of features in images? We used the class of 1-D images defined by Morrone and Burr in which the amplitude spectrum is that of a (partially blurred) square-wave and all Fourier components have a common phase. Observers used a cursor to mark where bars and edges were seen for different test phases (Experiment 1) or judged the spatial alignment of contours that had different phases (e.g. 0 degrees and 45 degrees ; Experiment 2). The feature positions defined by both tasks shifted systematically to the left or right according to the sign of the phase offset, increasing with the degree of blur. These shifts were well predicted by the location of luminance peaks (bars) and gradient peaks (edges), but not by energy peaks which (by design) predicted no shift at all. These results encourage models based on a Gaussian-derivative framework, but do not support the idea that human vision uses points of phase alignment to find local, first-order features. Nevertheless, we argue that both approaches are presently incomplete and a better understanding of early vision may combine insights from both. (C)2004 Elsevier Ltd. All rights reserved.

Bars and edges: what makes a feature for human vision?

There have been two main approaches to feature detection in human and computer vision - luminance-based and energy-based. Bars and edges might arise from peaks of luminance and luminance gradient respectively, or bars and edges might be found at peaks of local energy, where local phases are aligned across spatial frequency. This basic issue of definition is important because it guides more detailed models and interpretations of early vision. Which approach better describes the perceived positions of elements in a 3-element contour-alignment task? We used the class of 1-D images defined by Morrone and Burr in which the amplitude spectrum is that of a (partially blurred) square wave and Fourier components in a given image have a common phase. Observers judged whether the centre element (eg ±458 phase) was to the left or right of the flanking pair (eg 0º phase). Lateral offset of the centre element was varied to find the point of subjective alignment from the fitted psychometric function. This point shifted systematically to the left or right according to the sign of the centre phase, increasing with the degree of blur. These shifts were well predicted by the location of luminance peaks and other derivative-based features, but not by energy peaks which (by design) predicted no shift at all. These results on contour alignment agree well with earlier ones from a more explicit feature-marking task, and strongly suggest that human vision does not use local energy peaks to locate basic first-order features. [Supported by the Wellcome Trust (ref: 056093)]

Mach Bands: multi-scale spatial filtering and co-operative coding of edges and bars

Perception of Mach bands may be explained by spatial filtering ('lateral inhibition') that can be approximated by 2nd derivative computation, and several alternative models have been proposed. To distinguish between them, we used a novel set of ‘generalised Gaussian’ images, in which the sharp ramp-plateau junction of the Mach ramp was replaced by smoother transitions. The images ranged from a slightly blurred Mach ramp to a Gaussian edge and beyond, and also included a sine-wave edge. The probability of seeing Mach Bands increased with the (relative) sharpness of the junction, but was largely independent of absolute spatial scale. These data did not fit the predictions of MIRAGE, nor 2nd derivative computation at a single fine scale. In experiment 2, observers used a cursor to mark features on the same set of images. Data on perceived position of Mach bands did not support the local energy model. Perceived width of Mach bands was poorly explained by a single-scale edge detection model, despite its previous success with Mach edges (Wallis & Georgeson, 2009, Vision Research, 49, 1886-1893). A more successful model used separate (odd and even) scale-space filtering for edges and bars, local peak detection to find candidate features, and the MAX operator to compare odd- and even-filter response maps (Georgeson, VSS 2006, Journal of Vision 6(6), 191a). Mach bands are seen when there is a local peak in the even-filter (bar) response map, AND that peak value exceeds corresponding responses in the odd-filter (edge) maps.

Interaction of peptides, peptidomimetics and other drug candidates with the DI/tripeptide transport system in intestinal epithelial cells, using the in vitro caco-2 cell culture system

An uptake system was developed using Caco-2 cell monolayers and the dipeptide, glycyl-[3H]L-proline, as a probe compound. Glycyl-[3H]L-proline uptake was via the di-/tripeptide transport system (DTS) and, exhibited concentration-, pH- and temperature-dependency. Dipeptides inhibited uptake of the probe, and the design of the system allowed competitors to be ranked against one another with respect to affinity for the transporter. The structural features required to ensure or increase interaction with the DTS were defined by studying the effect of a series of glycyl-L-proline and angiotensin-converting enzyme (ACE)-inhibitor (SQ-29852) analogues on the uptake of the probe. The SQ-29852 structure was divided into six domains (A-F) and competitors were grouped into series depending on structural variations within specific regions. Domain A was found to prefer a hydrophobic function, such as a phenyl group, and was intolerant to positive charges and H+ -acceptors and donors. SQ-29852 analogues were more tolerant of substitutions in the C domain, compared to glycyl-L-proline analogues, suggesting that interactions along the length of the SQ-29852 molecule may override the effects of substitutions in the C domain. SQ-29852 analogues showed a preference for a positive function, such as an amine group in this region, but dipeptide structures favoured an uncharged substitution. Lipophilic substituents in domain D increased affinity of SQ-29852 analogues with the DTS. A similar effect was observed for ACE-NEP inhibitor analogues. Domain E, corresponding to the carboxyl group was found to be tolerant of esterification for SQ-29852 analogues but not for dipeptides. Structural features which may increase interaction for one series of compounds, may not have the same effect for another series, indicating that the presence of multiple recognition sites on a molecule may override the deleterious effect of anyone change. Modifying current, poorly absorbed peptidomimetic structures to fit the proposed hypothetical model may improve oral bioavailability by increasing affinity for the DTS. The stereochemical preference of the transporter was explored using four series of compounds (SQ-29852, lysylproline, alanylproline and alanylalanine enantiomers). The L, L stereochemistry was the preferred conformation for all four series, agreeing with previous studies. However, D, D enantiomers were shown in some cases to be substrates for the DTS, although exhibiting a lower affinity than their L, L counterparts. All the ACE-inhibitors and β-lactam antibiotics investigated, produced a degree of inhibition of the probe, and thus show some affinity for the DTS. This contrasts with previous reports that found several ACE inhibitors to be absorbed via a passive process, thus suggesting that compounds are capable of binding to the transporter site and inhibiting the probe without being translocated into the cell. This was also shown to be the case for oligodeoxynucleotide conjugated to a lipophilic group (vitamin E), and highlights the possibility that other orally administered drug candidates may exert non-specific effects on the DTS and possibly have a nutritional impact. Molecular modelling of selected ACE-NEP inhibitors revealed that the three carbonyl functions can be oriented in a similar direction, and this conformation was found to exist in a local energy-minimised state, indicating that the carbonyls may possibly be involved in hydrogen-bond formation with the binding site of the DTS.

Role of community acceptance in sustainable bioenergy projects in India

Community acceptance has been identified as one of the key requirements for a sustainable bioenergy project. However less attention has been paid to this aspect from developing nations and small projects perspective. Therefore this research examines the role of community acceptance for sustainable small scale bioenergy projects in India. While addressing the aim, this work identifies influence of community over bioenergy projects, major concerns of communities regarding bioenergy projects and factors influencing perceptions of communities about bioenergy projects. The empirical research was carried out on four bioenergy companies in India as case studies. It has been identified that communities have significant influence over bioenergy projects in India. Local air pollution, inappropriate storage of by-products and credibility of developer are identified as some of the important concerns. Local energy needs, benefits to community from bioenergy companies, level of trust on company and relationship between company and the community are some of the prime factors which influence community's perception on bioenergy projects. This research sheds light on important aspects related to community acceptance of bioenergy projects, and this information would help practitioners in understanding the community perceptions and take appropriate actions to satisfy them. © 2014 Elsevier Ltd.

Effects of rare-earth co-doping on the local structure of rare-earth phosphate glasses using high and low energy X-ray diffraction

Rare-earth co-doping in inorganic materials has a long-held tradition of facilitating highly desirable optoelectronic properties for their application to the laser industry. This study concentrates specifically on rare-earth phosphate glasses, (R2O3)x(R'2O3)y(P2O5)1-(x+y), where (R, R') denotes (Ce, Er) or (La, Nd) co-doping and the total rare-earth composition corresponds to a range between metaphosphate, RP3O9, and ultraphosphate, RP5O14. Thereupon, the effects of rare-earth co-doping on the local structure are assessed at the atomic level. Pair-distribution function analysis of high-energy X-ray diffraction data (Qmax = 28 Å-1) is employed to make this assessment. Results reveal a stark structural invariance to rare-earth co-doping which bears testament to the open-framework and rigid nature of these glasses. A range of desirable attributes of these glasses unfold from this finding; in particular, a structural simplicity that will enable facile molecular engineering of rare-earth phosphate glasses with 'dial-up' lasing properties. When considered together with other factors, this finding also demonstrates additional prospects for these co-doped rare-earth phosphate glasses in nuclear waste storage applications. This study also reveals, for the first time, the ability to distinguish between P-O and PO bonding in these rare-earth phosphate glasses from X-ray diffraction data in a fully quantitative manner. Complementary analysis of high-energy X-ray diffraction data on single rare-earth phosphate glasses of similar rare-earth composition to the co-doped materials is also presented in this context. In a technical sense, all high-energy X-ray diffraction data on these glasses are compared with analogous low-energy diffraction data; their salient differences reveal distinct advantages of high-energy X-ray diffraction data for the study of amorphous materials. © 2013 The Owner Societies.

Equilibration through local information exchange in networks

We study the equilibrium states of energy functions involving a large set of real variables, defined on the links of sparsely connected networks, and interacting at the network nodes, using the cavity and replica methods. When applied to the representative problem of network resource allocation, an efficient distributed algorithm is devised, with simulations showing full agreement with theory. Scaling properties with the network connectivity and the resource availability are found. © 2006 The American Physical Society.

Comparing transport emissions and impacts for energy recovery from domestic waste (EfW): centralised and distributed disposal options for two UK Counties

Many local authorities (LAs) are currently working to reduce both greenhouse gas emissions and the amount of municipal solid waste (MSW) sent to landfill. The recovery of energy from waste (EfW) can assist in meeting both of these objectives. The choice of an EfW policy combines spatial and non-spatial decisions which may be handled using Multi-Criteria Analysis (MCA) and Geographic Information Systems (GIS). This paper addresses the impact of transporting MSW to EfW facilities, analysed as part of a larger decision support system designed to make an overall policy assessment of centralised (large-scale) and distributed (local-scale) approaches. Custom-written ArcMap extensions are used to compare centralised versus distributed approaches, using shortest-path routing based on expected road speed. Results are intersected with 1-kilometre grids and census geographies for meaningful maps of cumulative impact. Case studies are described for two counties in the United Kingdom (UK); Cornwall and Warwickshire. For both case study areas, centralised scenarios generate more traffic, fuel costs and emitted carbon per tonne of MSW processed.

Economic and socio-economic evaluation of bioenergy schemes fueled with energy crops in Greece

The main aim of this thesis is to evaluate the economic and socio-economic viability of energy crops as raw material for bioenergy schemes at the local level. The case examined is Greece, a southern Mediterranean country. Based on the current state, on foreseen trends and on the information presented in the literature review (conducted at the beginning of the study), the main goal was defined as follows: To examine the evidence supporting a strong role for dedicated energy crops local bioenergy developments in Greece, a sector that is forecasted to be increasingly important in the short to medium term.' Two perennial energy crops, cardoon (Cynara cardunculus L.) and giant reed (Arundo donax L.) were evaluated. The thesis analysed their possible introduction in the agricultural system of Rhodope, northern Greece, as alternative land use, through comparative financial appraisal with the main conventional crops. Based on the output of this comparative analysis, the breakeven for the two selected energy crops was defined along with a sensitivity analysis for the risk of the potential implementation. Following, the author performed an economic and socio-economic evaluation of a district heating system fuelled with energy crops in the selected region. Finally, the author, acknowledging that bioenergy deployment should be studied in the context of innovations proceeded in examining the different perceptions of the key groups involved, farmers and potential end users. Results indicated that biomass exploitation for energy purposes is more likely to be accepted when it is seen clearly as one strand in a national energy, environmental and agricultural policy which embraces several sources of renewable energy, and which also encourages energy efficiency and conservation.

The development of a regional energy assessment model

Shropshire Energy Team initiated this study to examine consumption and associated emissions in the predominantly rural county of Shropshire. Current use of energy is not sustainable in the long term and there are various approaches to dealing with the environmental problems it creates. Energy planning by a local authority for a sustainable future requires detailed energy consumption and environmental information. This information would enable target setting and the implementation of policies designed to encourage energy efficiency improvements and exploitation of renewable energy resources. This could aid regeneration strategies by providing new employment opportunities. Associated reductions in carbon dioxide and other emissions would help to meet national and international environmental targets. In the absence of this detailed information, the objective was to develop a methodology to assess energy consumption and emissions on a regional basis from 1990 onwards for all local planning authorities. This would enable a more accurate assessment of the relevant issues, such that plans are more appropriate and longer lasting. A first comprehensive set of data has been gathered from a wide range of sources and a strong correlation was found between population and energy consumption for a variety of regions across the UK. In this case the methodology was applied to the county of Shropshire to give, for the first time, estimates of primary fuel consumption, electricity consumption and associated emissions in Shropshire for 1990 to 2025. The estimates provide a suitable baseline for assessing the potential contribution renewable energy could play in meeting electricity demand in the country and in reducing emissions. The assessment indicated that in 1990 total primary fuel consumption was 63,518,018 GJ/y increasing to 119,956,465 GJ/y by 2025. This is associated with emissions of 1,129,626 t/y of carbon in 1990 rising to 1,303,282 t/y by 2025. In 1990, 22,565,713 GJ/y of the primary fuel consumption was used for generating electricity rising to 23,478,050 GJ/y in 2025. If targets to reduce primary fuel consumption are reached, then emissions of carbon would fall to 1,042,626 by 2025, if renewable energy targets were also reached then emissions of carbon would fall to 988,638 t/y by 2025.

The political shaping of energy technology:combined heat and power in Britain

There has been negligible adoption of combined heat and power (CHP) for district heating (DH) in Britain, despite continued advocacy. This thesis constructs an account of the treatment of the option, and devises a framework for explanation. Analysis of technological development and adoption, it is argued, should be similar to that of other social processes, and be subject to the same requirements and criticisms. They will, however, show features peculiar to the institutions developing and selecting technologies, their relation to different social groups, and the forms of knowledge in and about technology. Conventional approaches - organisation and interorganisation theories, and analyses of policy-making - give useful insights but have common limitations. Elements of an analytical framework situating detailed issues and outcomes in a structured historical context are derived from convergent radical critiques. Thus activity on CHP/DH is essentially shaped by the development and relations of energy sector institutions: central and local government, nationalised industries and particularly the electricity industry. Analysis of them is related to the specific character of the British state. A few CHP and DH installations were tried before 1940. During postwar reconstruction, extensive plans for several cities were abandoned or curtailed. In the 1960s and 70s, many small non-CHP DH schemes were installed on housing estates. From the mid-70s, the national potential of CHP/DH has been reappraised, with widespread support and favourable evaluations, but little practical progress. Significant CHP/DH adoption is shown to have been systematically excluded ultimately by the structure of energy provision; centralised production interests dominate and co-ordination is weak. Marginal economics and political commitment have allowed limited development in exceptional circumstances. Periods of upheaval provided greater opportunity and incentive for CHP/DH but restructuring eventually obstructed it. Explanation of these outcomes is shown to require analysis at several levels, from broad context to detailed action.

Omnigen:providing electricity, food preparation, cold storage and pure water using a variety of local fuels

We describe a polygeneration system that can run on neat plant oils, such as Jatropha and Pongamia, or standard diesel fuel. A prototype has been constructed using a compression ignition engine of 9.9 kW shaft output. It consumes 3 L/h of fuel and will produce 40 kg/h of ice by means of an adsorption refrigerator powered from the engine jacket heat. Steaming of rice, deep and shallow frying, and other types of food preparation heated by the exhaust gas have been demonstrated. In addition, the feasibility of producing distilled water by means of multiple-effect distillation powered by the engine waste heat is shown. Overall plant efficiency and potential savings in greenhouse gas emissions are discussed. © 2012 Elsevier Ltd.

The madness that is the world:young activists' emotional reasoning and their participation in a local Occupy movement

The focus of this paper is young people’s participation in the Occupy protest movement that emerged in the early autumn of 2011. Its concern is with the emotional dimensions of this and in particular the significance of emotions to the reasoning of young people who came to commit significant time and energy to the movement. Its starting point is the critique of emotions as narrowly subjective, whereby the passions that events like Occupy arouse are treated as beyond the scope of human reason. The rightful rejection of this reductionist argument has given rise to an interest in under- standings of the emotional content of social and political protest as normatively con- stituted, but this paper seeks a different perspective by arguing that the emotions of Occupy activists can be regarded as a reasonable force. It does so by discussing find- ings from long-term qualitative research with a Local Occupy movement somewhere in England and Wales. Using the arguments of social realists, the paper explores this data to examine why things matter sufficiently for young people to care about them and how the emotional force that this involves constitutes an indispensable source of reason in young activists’ decisions to become involved in Local Occupy.