The primal sketch revisited: locating and representing edges in human vision via Gaussian-derivative filtering

Marr's work offered guidelines on how to investigate vision (the theory - algorithm - implementation distinction), as well as specific proposals on how vision is done. Many of the latter have inevitably been superseded, but the approach was inspirational and remains so. Marr saw the computational study of vision as tightly linked to psychophysics and neurophysiology, but the last twenty years have seen some weakening of that integration. Because feature detection is a key stage in early human vision, we have returned to basic questions about representation of edges at coarse and fine scales. We describe an explicit model in the spirit of the primal sketch, but tightly constrained by psychophysical data. Results from two tasks (location-marking and blur-matching) point strongly to the central role played by second-derivative operators, as proposed by Marr and Hildreth. Edge location and blur are evaluated by finding the location and scale of the Gaussian-derivative `template' that best matches the second-derivative profile (`signature') of the edge. The system is scale-invariant, and accurately predicts blur-matching data for a wide variety of 1-D and 2-D images. By finding the best-fitting scale, it implements a form of local scale selection and circumvents the knotty problem of integrating filter outputs across scales. [Supported by BBSRC and the Wellcome Trust]

Aggregate dividends and consumption smoothing

We show that net equity payouts from the corporate sector play a crucial role in helping individuals manage their consumption path across the business cycle. In particular, we show that, as investors' desire to smooth consumption increases, optimal aggregate dividends become both more volatile and more counter-cyclical to help counterbalance pro-cyclical labor income. These findings are robust to whether or not agency conflicts exist in the economy.

Fluorescent probe:complexation of Fe3+ with the myo-inositol 1,2,3-trisphosphate motif

Natural myo-inositol phosphate antioxidants containing the 1,2,3-trisphosphate motif bind Fe3+ in the unstable penta-axial conformation.

Fluorescent probe for detection of bacteria:conformational trigger upon bacterial reduction of an azo bridge

Using biomimetic chemical reduction or Clostridium perfringens cell extract containing azoreductase, the dimer-fluorescent probe 2,4-O-bisdansyl-6,7- diazabicyclooct-6-ene, which possesses a conformationally constrained cis-azo bridge, is reduced to the tetra-equatorial 2,4-O-bisdansyl-cyclohexyl-3,5- bisammonium salt which exhibits fluorescence indicative of a dansyl monomer. © 2012 The Royal Society of Chemistry.

Conformational analysis of the natural iron chelator myo-inositol 1,2,3-trisphosphate using a pyrene-based fluorescent mimic

myo-Inositol phosphates possessing the 1,2,3-trisphosphate motif share the remarkable ability to completely inhibit iron-catalysed hydroxyl radical formation. The simplest derivative, myo-inositol 1,2,3-trisphosphate [Ins(1,2,3)P3], has been proposed as an intracellular iron chelator involved in iron transport. The binding conformation of Ins(1,2,3)P3 is considered to be important to complex Fe3+ in a 'safe' manner. Here, a pyrene-based fluorescent probe, 4,6-bispyrenoyl-myo-inositol 1,2,3,5-tetrakisphosphate [4,6-bispyrenoyl Ins(1,2,3,5)P4], has been synthesised and used to monitor the conformation of the 1,2,3-trisphosphate motif using excimer fluorescence emission. Ring-flip of the cyclohexane chair to the penta-axial conformation occurs upon association with Fe3+, evident from excimer fluorescence induced by π-π stacking of the pyrene reporter groups, accompanied by excimer formation by excitation at 351 nm. This effect is unique amongst biologically relevant metal cations, except for Ca 2+ cations exceeding a 1:1 molar ratio. In addition, the thermodynamic constants for the interaction of the fluorescent probe with Fe3+ have been determined. The complexes formed between Fe 3+ and 4,6-bispyrenoyl Ins(1,2,3,5)P4 display similar stability to those formed with Ins(1,2,3)P3, indicating that the fluorescent probe acts as a good model for the 1,2,3-trisphosphate motif. This is further supported by the antioxidant properties of 4,6-bispyrenoyl Ins(1,2,3,5)P4, which closely resemble those obtained for Ins(1,2,3)P3. The data presented confirms that Fe3+ binds tightly to the unstable penta-axial conformation of myo-inositol phosphates possessing the 1,2,3-trisphosphate motif. © 2010 The Royal Society of Chemistry.

Synthesis and iron binding studies of myo-inositol 1,2,3-trisphosphate and (+/-)-myo-inositol 1,2-bisphosphate, and iron binding studies of all myo-inositol tetrakisphosphates

The first syntheses of the natural products myo-inositol 1,2,3-trisphosphate and (+/-)-myo-inositol 1,2-bisphosphate are described. The protected key intermediates 4,5,6-tri-O-benzoyl-myo-inositol and (+/-)-3,4,5,6-tetra-O-benzyl-myo-inositol were phosphorylated with dibenzyl N,N-di-isopropylphosphoramidite in the presence of 1H-tetrazole and subsequent oxidation of the phosphite. The crystal structures of the synthetic intermediates (+/-)-1-O-(tert-butyldiphenylsilyl)-2,3,O-cyclohexylidene-myo-inos itol and (+/-)-4,5,6-tri-O-benzoyl-1-O-(tert-butyldiphenylsilyl)-2,3-O-cycl ohexylidene- myo-inositol are reported. myo-Inositol 1,2,3-trisphosphate (+/-)-myo-inositol 1,2-bisphosphate, and all isomeric myo-inositol tetrakisphosphates were evaluated for their ability to alter HO. production in the iron-catalysed Haber-Weiss reaction. The results demonstrated that a 1,2,3-grouping of phosphates in myo-inositol was necessary for inhibition also that (+/-)-myo-inositol 1,2-bisphosphate potentiated HO. production. myo-Inositol 1,2,3-trisphosphate resembled myo-inositol hexakisphosphate (phytic acid) in its ability to act as a siderophore by promoting iron-uptake into Pseudomonas aeruginosa.

From national innovation systems to national innovation capacity:internationalisation and technology transfer perspectives

The last decade or so has witnessed the emergence of the national innovation system (NIS) phenomenon. Since then, many scholars have investigated NIS and its implementation in different countries. However, there are very few investigations into the relationship between the NIS of a country and its national innovation capacity. This paper aims to make a contribution in this area by examining the link that currently exists between these two topics. Whilst examining this relationship, we also explore internationalisation and technology transfer, being cognate areas that have been investigated during the same period. This follows our assertion that the link between NIS and national innovation capacity is the mechanism of internationalisation and technology transfer. The NIS approach was introduced in the late 1980s (see Freeman, 1987; Dosi et al., 1988) and further elaborated later (see Lundvall, 1992; Nelson, 1993; Edquist, 1997). In essence, a country?s NIS is a historically grown subsystem of the entire national economy consisting of organisations and institutions which play a major role in the innovative activity in the country. In the NIS approach, interactions within organisations as well as the interplay between organisations and institutions are of central importance. The NIS approach has been used to reveal the structure of the innovation processes and the main actors involved in them in industrialised and emerging countries. Although the national focus remains strong, it has been accompanied by studies seeking to analyse the notion of systems of innovation at an international level and at a sub-national scale (Archibugi et al., 1999). Dosi in the edition of Archibugi et al. (1999) argues that the general background of the discussion of national systems is the observation of non-random distributions across countries of: corporate capabilities; organisational forms; strategies; and ultimately revealed performances, in terms of production efficiency and inputs productivities, rates of innovation, rates of adoption/diffusion of innovation themselves, dynamics of market shares on the world markets, growth of income and employment. They also mention that there are several approaches to NIS. Nelson (1993) focuses upon the specificities of national institutions and policies supporting directly or indirectly innovation, diffusion and skills accumulation. Patel and Pavitt (1991) have stressed the links between the national patterns of technological accumulation and the competencies and innovative strategies of a few major national companies. Amable et al (1997) and Soskice (1993) and Zysman (1994) focus on the specifics of national institutions including, for example, the forms of organization, financial and labour markets, training institutions, forms of state intervention in the economy etc. However, the most common reference is by Lundvall (1992) who argues that the focus on the national level is associated with the fact that national economies vary according to their production system and their institutional framework and these differences are in turn strengthened by different historical experiences, language and culture. On the other hand, the national innovation capability consists of abilities to create and carry new technological possibilities through to economic practice. The term covers a wide range of activities from capability to invent to capability to innovate and to capability to improve existing technology beyond the original design parameters (Kim, 1997). The term innovation is often associated by many with technological change at international frontiers. However, technological capability is not the same as innovation capability. Technological capability refers to assimilation, use, adaptation, and change to existing technologies. It also enables the creation of new technologies and development of new products and processes in response to changing economic environments. It denotes operational command over knowledge (Kim, 1997). It is manifested not merely by the knowledge possessed, but, more important, by the uses to which that knowledge can be put and by the proficiency with which it is applied in the activities of investment and production and in the creation of new knowledge (Westphal et al., 1985). Therefore, the analytical framework that is used in this paper is based on the way a country derives from its NIS a national innovation capacity. There are two perspectives that are identified on this way. These are internationalisation and technology transfer. Even though NIS is not directly related to national innovation capacity, to achieve national innovation capacity from NIS, the country should have the ability for technology transfer. Technology transfer is a link between these two phenomena. On the other hand, internationalisation can be either the input or the output of the relationship between NIS and national innovation capability. If a company is investing in a country because of its national innovation capacity, this can be regarded as an input to the relationship between NIS and national innovation capacity. If this company is investigating the national innovation capacity of a country then, for its internationalisation, the national innovation capacity should be important, which in turn means this company is active in innovation and innovation is also an important success factor. The interrelationship between the investment of the company and the NIS of the country (assuming that the country is competent and competitive in technology transfer) will generate and improve that country?s national innovation capacity. This is the output of internationalisation from the relationship between NIS and national innovation capacity. When companies are evaluating whether to internationalise, they investigate certain factors in the countries in which they are considering to invest. The ability to transfer technology is dependent on ability to adopt a new technology and also on the learning derived from this technology. If countries wish to attract innovation related investment they need to show their ability to have a NIS and also the capability to transfer technology. Without the technology transfer capability, the NIS is not functioning. Therefore, companies that internationalise will investigate the factors common to NIS, technology transfer, and their business needs. Through this paper we will demonstrate this link though its mechanisms. Our research will be through extensive literature review and identifying relevant aspects of previous research carried out by the authors. It will investigate certain factors of different countries that are successful in attracting innovation related foreign direct investment. Through these, we will point out the factors that are important for the link and mechanisms of NIS and national innovation capability.

From filters to features:Scale-space analysis of edge and blur coding in human vision

To make vision possible, the visual nervous system must represent the most informative features in the light pattern captured by the eye. Here we use Gaussian scale-space theory to derive a multiscale model for edge analysis and we test it in perceptual experiments. At all scales there are two stages of spatial filtering. An odd-symmetric, Gaussian first derivative filter provides the input to a Gaussian second derivative filter. Crucially, the output at each stage is half-wave rectified before feeding forward to the next. This creates nonlinear channels selectively responsive to one edge polarity while suppressing spurious or "phantom" edges. The two stages have properties analogous to simple and complex cells in the visual cortex. Edges are found as peaks in a scale-space response map that is the output of the second stage. The position and scale of the peak response identify the location and blur of the edge. The model predicts remarkably accurately our results on human perception of edge location and blur for a wide range of luminance profiles, including the surprising finding that blurred edges look sharper when their length is made shorter. The model enhances our understanding of early vision by integrating computational, physiological, and psychophysical approaches. © ARVO.

Blurred edges look faint, and faint edges look sharp:The effect of a gradient threshold in a multi-scale edge coding model

A multi-scale model of edge coding based on normalized Gaussian derivative filters successfully predicts perceived scale (blur) for a wide variety of edge profiles [Georgeson, M. A., May, K. A., Freeman, T. C. A., & Hesse, G. S. (in press). From filters to features: Scale-space analysis of edge and blur coding in human vision. Journal of Vision]. Our model spatially differentiates the luminance profile, half-wave rectifies the 1st derivative, and then differentiates twice more, to give the 3rd derivative of all regions with a positive gradient. This process is implemented by a set of Gaussian derivative filters with a range of scales. Peaks in the inverted normalized 3rd derivative across space and scale indicate the positions and scales of the edges. The edge contrast can be estimated from the height of the peak. The model provides a veridical estimate of the scale and contrast of edges that have a Gaussian integral profile. Therefore, since scale and contrast are independent stimulus parameters, the model predicts that the perceived value of either of these parameters should be unaffected by changes in the other. This prediction was found to be incorrect: reducing the contrast of an edge made it look sharper, and increasing its scale led to a decrease in the perceived contrast. Our model can account for these effects when the simple half-wave rectifier after the 1st derivative is replaced by a smoothed threshold function described by two parameters. For each subject, one pair of parameters provided a satisfactory fit to the data from all the experiments presented here and in the accompanying paper [May, K. A. & Georgeson, M. A. (2007). Added luminance ramp alters perceived edge blur and contrast: A critical test for derivative-based models of edge coding. Vision Research, 47, 1721-1731]. Thus, when we allow for the visual system's insensitivity to very shallow luminance gradients, our multi-scale model can be extended to edge coding over a wide range of contrasts and blurs. © 2007 Elsevier Ltd. All rights reserved.

Added luminance ramp alters perceived edge blur and contrast:A critical test for derivative-based models of edge coding

In many models of edge analysis in biological vision, the initial stage is a linear 2nd derivative operation. Such models predict that adding a linear luminance ramp to an edge will have no effect on the edge's appearance, since the ramp has no effect on the 2nd derivative. Our experiments did not support this prediction: adding a negative-going ramp to a positive-going edge (or vice-versa) greatly reduced the perceived blur and contrast of the edge. The effects on a fairly sharp edge were accurately predicted by a nonlinear multi-scale model of edge processing [Georgeson, M. A., May, K. A., Freeman, T. C. A., & Hesse, G. S. (in press). From filters to features: Scale-space analysis of edge and blur coding in human vision. Journal of Vision], in which a half-wave rectifier comes after the 1st derivative filter. But we also found that the ramp affected perceived blur more profoundly when the edge blur was large, and this greater effect was not predicted by the existing model. The model's fit to these data was much improved when the simple half-wave rectifier was replaced by a threshold-like transducer [May, K. A. & Georgeson, M. A. (2007). Blurred edges look faint, and faint edges look sharp: The effect of a gradient threshold in a multi-scale edge coding model. Vision Research, 47, 1705-1720.]. This modified model correctly predicted that the interaction between ramp gradient and edge scale would be much larger for blur perception than for contrast perception. In our model, the ramp narrows an internal representation of the gradient profile, leading to a reduction in perceived blur. This in turn reduces perceived contrast because estimated blur plays a role in the model's estimation of contrast. Interestingly, the model predicts that analogous effects should occur when the width of the window containing the edge is made narrower. This has already been confirmed for blur perception; here, we further support the model by showing a similar effect for contrast perception. © 2007 Elsevier Ltd. All rights reserved.

Investigating the supply and demand relationship in a profession: the English and Welsh schools of librarianship and information Studies and the Higher Education Library and Information Services employment sector in England and Wales.

Concern has been expressed in the professional literature - borne out by professional experience and observation - that the supply and demand relationship existing between the 13 English and Welsh Library and Information Studies (LIS) Schools (as providers of `First Professional' staff) and the Higher Education Library and Information Services (HE LIS) sector of England and Wales (as one group of employers of such staff) is unsatisfactory and needs attention. An appropriate methodology to investigate this problem was devised. A basic content analysis of Schools' curricular and recruitment material intended for public consumption was undertaken to establish an overview of the LIS initial professional education system in England and Wales, and to identify and analyse any covert messages imparted to readers. This was followed by a mix of Main Questionnaires and Semi-Structured Interviews with appropriate populations. The investigation revealed some serious areas of dissatisfaction by the HE LIS Chiefs with the role and function of the Schools. Considerable divergence of views emerged on the state of the working relationships between the two sectors and on the Schools' successes in meeting the needs of the HE LIS sector and on CPD provision. There were, however, areas of substantial and consistent agreement between the two sectors. The main implications of the findings were that those areas encompassing divergence of views were worrying and needed addressing by both sides. Possible ways forward included recommendations on improving the image of the profession purveyed by the Schools; the forming of closer and more effective inter-sectoral relationships; recognising fully the importance of `practicum' and increasing and sustaining the network of `practicum' providers.

Conformational Evaluation of Indol-3-yl-N-alkyl-glyoxalylamides and Indol-3-yl-N,N-dialkyl-glyoxalylamides

Restricted rotation in indol-3-yl-N-alkyl- and indol-3-yl-N,N-dialkyl-glyoxalylamides can in principle give the syn-periplanar and anti-periplanar rotamers. In asymmetrically disubstituted glyoxalylamides, steric effects lead to the occurrence of both rotamers, as observed by NMR spectroscopy. The predominant peak corresponds with the anti rotamer, in which the bulkier alkyl group is orientated trans to the amide carbonyl group. In monoalkylated glyoxalylamides, only one set of peaks is observed, consistent with the presence of only one rotamer. Crystal structures of 5-methoxyindole-3-yl-N-tert-butylglyoxalylamide, indole-3-yl-N-tert-butylglyoxalylamide, and indole-3-yl-N-isopropylglyoxalylamide reported here reveal a syn conformation held by an intramolecular N-HO hydrogen bond.

Researching language teacher cognition and practice:international case studies

This book presents a novel approach to discussing how to research language teacher cognition and practice. An introductory chapter by theeditors and an overview of the research field by Simon Borg precede eigh case studies written by new researchers, each of which focuses on one approach to collecting data. These approaches range from questionnaires and focus groups to think aloud, stimulated recall, and oral reflective journals. Each case study is commented on by a leading expert in the field - JD Brown, Martin Bygate, Donald Freeman, Alan Maley, Jerry Gebhard, Thoma Farrell, Susan Gass, and Jill Burton. Readers are encouraged to enter th conversation by reflecting on a set of questions and tasks in each chapter.