Zero-dimensional noise:the best mask you never saw

The transmission of weak signals through the visual system is limited by internal noise. Its level can be estimated by adding external noise, which increases the variance within the detecting mechanism, causing masking. But experiments with white noise fail to meet three predictions: (a) noise has too small an influence on the slope of the psychometric function, (b) masking occurs even when the noise sample is identical in each two-alternative forced-choice (2AFC) interval, and (c) double-pass consistency is too low. We show that much of the energy of 2D white noise masks extends well beyond the pass-band of plausible detecting mechanisms and that this suppresses signal activity. These problems are avoided by restricting the external noise energy to the target mechanisms by introducing a pedestal with a mean contrast of 0% and independent contrast jitter in each 2AFC interval (termed zero-dimensional [0D] noise). We compared the jitter condition to masking from 2D white noise in double-pass masking and (novel) contrast matching experiments. Zero-dimensional noise produced the strongest masking, greatest double-pass consistency, and no suppression of perceived contrast, consistent with a noisy ideal observer. Deviations from this behavior for 2D white noise were explained by cross-channel suppression with no need to appeal to induced internal noise or uncertainty. We conclude that (a) results from previous experiments using white pixel noise should be re-evaluated and (b) 0D noise provides a cleaner method for investigating internal variability than pixel noise. Ironically then, the best external noise stimulus does not look noisy.

Interfacing low-energy SAW nebulization with liquid chromatography-mass spectrometry for the analysis of biological samples

Soft ionization methods for the introduction of labile biomolecules into a mass spectrometer are of fundamental importance to biomolecular analysis. Previously, electrospray ionization (ESI) and matrix assisted laser desorption-ionization (MALDI) have been the main ionization methods used. Surface acoustic wave nebulization (SAWN) is a new technique that has been demonstrated to deposit less energy into ions upon ion formation and transfer for detection than other methods for sample introduction into a mass spectrometer (MS). Here we report the optimization and use of SAWN as a nebulization technique for the introduction of samples from a low flow of liquid, and the interfacing of SAWN with liquid chromatographic separation (LC) for the analysis of a protein digest. This demonstrates that SAWN can be a viable, low-energy alternative to ESI for the LC-MS analysis of proteomic samples.

Does translation hinder integration?

2006 and 2007 saw renewed debates about rising costs of public sector translation and interpreting. One argument put forward was that the provision of such services for the immigrant population is deterring community cohesion in the UK. For example, the former education secretary Ruth Kelly raised the question of whether we are providing a ‘crutch’ by making translations available to immigrants, thus not giving them the incentive to learn English. The paper will address this question in the context of language policies and language ideologies in the UK. It will be argued that the debate about translation services has been instrumentalised for the discursive construction of identities.

The other on display: translation in the Ethnographic Museum

The ethnographic museum in the West has a long and troubling history. The display of 'exotic peoples' in travelling exhibitions began as early as the sixteenth century, but it was the mid and late nineteenth century that saw the great expansion of museums as sites to show artefacts collected - under anything but reputable circumstances - from what were considered the 'primitive', 'natural', or 'tribal' peoples of the world. Today the ethnographic museum is still a feature of large European cities, though faced with newly formulated dilemmas in the postcolonial world. For how can the material culture of a non-western people be collected and displayed in the West without its makers being translated into wordless and powerless objects of visual consumption? In national museums the processes of choosing, contextualizing and commentating exhibits help form national identity; in the ethnographic museum, similarly, they shape perceptions of the apparently distant Other. Like written ethnography, the museum is a 'translation of culture', with many of the associated problems traced by Talal Asad (1986). Like the written form, it has to represent the dialogic realities of cultural encounters in a fixed and intelligible form, to propose categories that define and order the material it has gathered. As the public face of academic ethnography, the museum interprets other cultures for the benefit of the general reader, and in that task museum practice, like all ethnography, operates within very specific historical and political parameters. How are museums in western Europe responding to the issues raised by critical ethnographers like James Clifford (1988), with their focus on the politics of representation? Is globalisation increasing the degree of accountability imposed on the ethnographic museum, or merely reinforcing older patterns? What opportunities and problems are raised by the use of more words - more 'translation' in the narrower sense - in ethnographic museums, and how do museums gain from introducing a reflexive and contextualizing concept of "thick translation" (Appiah 1993) into their work of interpretation?

Modulation of neuronal network activity in the primary motor cortex

In the present study I investigated the mechanisms of modulation of neuronal network activity in rat primary motor cortex using pharmacological manipulations employing the in vitro brain slice technique. Preparation of the brain slice in sucrose-based aCSF produced slices with low viability. Introducing the neuroprotectants N-acetyl-cysteine, taurine and aminoguanidine to the preparatory method saw viability of slices increase significantly. Co-application of low dose kainic acid and carbachol consistently generated beta oscillatory activity in M1. Analyses indicated that network activity in M1 relied on the involvement of GABAA receptors. Dose-response experiments performed in M1 showed that beta activity can be modulated by benzodiazepine site ligands. Low doses of positive allosteric modulators consistently desynchronised beta oscillatory activity, a mechanism that may be driven by a1-subunit containing GABAA receptors. Higher doses increased the power of beta oscillatory activity. Whole-cell recordings in M1 uncovered three interneuronal subtypes regularly encountered in M1; Fast-spiking, regular-spiking non-Pyramidal and low threshold spiking. With the paradoxical effects of positive allosteric modulators in mind, subsequent voltage-clamp recordings in FS cells revealed a constitutively active tonic inhibitory current that could be modulated by zolpidem in two different ways. Low dose zolpidem increased the tonic inhibitory current in FS cells, consistent with the desynchronisation of network oscillatory activity seen at this concentration. High dose zolpidem decreased the inhibitory tonic current seen in FS cells, coinciding with an increase in oscillatory power. These studies indicate a fundamental role for a tonic inhibitory current in the modulation of network activity. Furthermore, desynchronisation of beta activity in M1 decreased as viability of the in vitro brain slice increased, suggesting that the extent of desynchronisation is dependent upon the pathophysiological state of the network. This indicates that low dose zolpidem could be used as a therapeutic agent specifically for the desynchronisation of pathological oscillations in oscillopathies such as Parkinson’s disease.

New networked technologies and carers of people with dementia: an interview study

Dementia is one of the greatest contemporary health and social care challenges, and novel approaches to the care of its sufferers are needed. New information and communication technologies (ICT) have the potential to assist those caring for people with dementia, through access to networked information and support, tracking and surveillance. This article reports the views about such new technologies of 34 carers of people with dementia. We also held a group discussion with nine carers for respondent validation. The carers' actual use of new ICT was limited, although they thought a gradual increase in the use of networked technology in dementia care was inevitable but would bypass some carers who saw themselves as too old. Carers expressed a general enthusiasm for the benefits of ICT, but usually not for themselves, and they identified several key challenges including: establishing an appropriate balance between, on the one hand, privacy and autonomy and, on the other: maximising safety; establishing responsibility for and ownership of the equipment and who bears the costs; the possibility that technological help would mean a loss of valued personal contact; and the possibility that technology would substitute for existing services rather than be complementary. For carers and dementia sufferers to be supported, the expanding use of these technologies should be accompanied by intensive debate of the associated issues.

A study of the attitudes towards unethical selling amongst Chinese salespeople

The latter part of the twentieth century saw the Chinese economy moving towards a socialist market economy rather than a planned system. Despite growing interest in Chinese business ethics, little work has examined ethical issues concerning the Chinese sales force. This study draws from existing work on Chinese and Western business and sales ethics to develop hypotheses regarding the perceptions of unethical selling behaviour of modern Chinese salespeople. A survey of Chinese sales executives is conducted and statistically analysed. Results are compared with those reported in previous US-based research with regard to differences in perceptions of unethical selling behaviour. The results indicate that contemporary Chinese salespeople were more favourably disposed than expected towards unethical selling behaviour, and also more favourably disposed than previously studied US salespeople. Younger Chinese salespeople evaluated unethical behaviours more favourably than older ones. The results are discussed, along with implications for theory, practice and future work.

Seeing light vs dark lines: psychophysical performance is based on separate channels, limited by noise and uncertainty

Visual detection performance (d') is usually an accelerating function of stimulus contrast, which could imply a smooth, threshold-like nonlinearity in the sensory response. Alternatively, Pelli (1985 Journal of the Optical Society of America A 2 1508 - 1532) developed the 'uncertainty model' in which responses were linear with contrast, but the observer was uncertain about which of many noisy channels contained the signal. Such internal uncertainty effectively adds noise to weak signals, and predicts the nonlinear psychometric function. We re-examined these ideas by plotting psychometric functions (as z-scores) for two observers (SAW, PRM) with high precision. The task was to detect a single, vertical, blurred line at the fixation point, or identify its polarity (light vs dark). Detection of a known polarity was nearly linear for SAW but very nonlinear for PRM. Randomly interleaving light and dark trials reduced performance and rendered it non-linear for SAW, but had little effect for PRM. This occurred for both single-interval and 2AFC procedures. The whole pattern of results was well predicted by our Monte Carlo simulation of Pelli's model, with only two free parameters. SAW (highly practised) had very low uncertainty. PRM (with little prior practice) had much greater uncertainty, resulting in lower contrast sensitivity, nonlinear performance, and no effect of external (polarity) uncertainty. For SAW, identification was about v2 better than detection, implying statistically independent channels for stimuli of opposite polarity, rather than an opponent (light - dark) channel. These findings strongly suggest that noise and uncertainty, rather than sensory nonlinearity, limit visual detection.

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]

Contextualising accounts of illness:Notions of responsibility and blame in white and South Asian respondents' accounts of diabetes causation

We undertook a secondary analysis of in-depth interviews with white (n = 32) and Pakistani and Indian (n = 32) respondents who had type 2 diabetes, which explored their perceptions and understandings of disease causation. We observed subtle, but important, differences in the ways in which these respondent groups attributed responsibility and blame for developing the disease. Whereas Pakistani and Indian respondents tended to externalise responsibility, highlighting their life circumstances in general and/or their experiences of migrating to Britain in accounting for their diabetes (or the behaviours they saw as giving rise to it), white respondents, by contrast, tended to emphasise the role of their own lifestyle 'choices' and 'personal failings'. In seeking to understand these differences, we argue for a conceptual and analytical approach which embraces both micro- (i.e. everyday) and macro- (i.e. cultural) contextual factors and experiences. In so doing, we provide a critique of social scientific studies of lay accounts/understandings of health and illness. We suggest that greater attention needs to be paid to the research encounter (that is, to who is looking at whom and in what circumstances) to understand the different kinds of contexts researchers have highlighted in presenting and interpreting their data. © 2007 Foundation for the Sociology of Health & Illness/Blackwell Publishing Ltd.

Self monitoring of blood glucose in type 2 diabetes:Longitudinal qualitative study of patients' perspectives

Objective: To explore views of patients with type 2 diabetes about self monitoring of blood glucose over time. Design: Longitudinal, qualitative study. Setting: Primary and secondary care settings across Lothian, Scotland. Participants: 18 patients with type 2 diabetes. Main outcome measures: Results from repeat in-depth interviews with patients over four years after clinical diagnosis. Results: Analysis revealed three main themes - the role of health professionals, interpreting readings and managing high values, and the ongoing role of blood glucose self monitoring. Self monitoring decreased over time, and health professionals' behaviour seemed crucial in this: participants interpreted doctors' focus on levels of haemoglobin A1c, and lack of perceived interest in meter readings, as indicating that self monitoring was not worth continuing. Some participants saw readings as a proxy measure of good and bad behaviour - with women especially, chastising themselves when readings were high. Some participants continued to find readings difficult to interpret, with uncertainty about how to respond to high readings. Reassurance and habit were key reasons for continuing. There was little indication that participants were using self monitoring to effect and maintain behaviour change. Conclusions: Clinical uncertainty about the efficacy and role of blood glucose self monitoring in patients with type 2 diabetes is mirrored in patients' own accounts. Patients tended not to act on their self monitoring results, in part because of a lack of education about the appropriate response to readings. Health professionals should be explicit about whether and when such patients should self monitor and how they should interpret and act upon the results, especially high readings.

Surface acoustic wave devices with low loss and high frequency operation

This thesis describes an industrial research project carried out in collaboration with STC Components, Harlow, Essex. Technical and market trends in the use of surface acoustic wave (SAW) devices are reviewed. As a result, three areas not previously addressed by STC were identified: lower insertion loss designs, higher operating frequencies and improved temperature dependent stability. A review of the temperature performance of alternative lower insertion loss designs,shows that greater use could be made of the on-site quartz growing plant. Data is presented for quartz cuts in the ST-AT range. This data is used to modify the temperature performance of a SAW filter. Several recently identified quartz orientations have been tested. These are SST, LST and X33. Problems associated with each cut are described and devices demonstrated. LST quartz, although sensitive to accuracy of cut, is shown to have an improved temperature coefficient over the normal ST orientation. Results show that its use is restricted due to insertion loss variations with temperature. Effects associated with split-finger transducers on LST-quartz are described. Two low-loss options are studied, coupled resonator filters for very narrow bandwidth applications and single phase unidirectional transducers (SPUDT) for fractional bandwidths up to about 1%. Both designs can be implemented with one quarter wavelength transducer geometries at operating frequencies up to 1GHz. The SPUDT design utilised an existing impulse response model to provide analysis of ladder or rung transducers. A coupled resonator filter at 400MHz is demonstrated with a matched insertion loss of less than 3.5dB and bandwidth of 0.05%. A SPUDT device is designed as a re-timing filter for timing extraction in a long haul PCM transmission system. Filters operating at 565MHz are demonstrated with insertion losses of less than 6dB. This basic SPUDT design is extended to a maximally distributed version and demonstrated at 450MHz with 9.8dB insertion loss.

The work situation and class position of Brazilian engineers

This thesis analyses the work situation and class position of Brazilian engineers through a Marxist perspective. The research is based on two case studies, one focused on a large German steel company based in Brazil and the other on a large Brazilian energy corporation. The fieldwork involved 114 interviews, with engineers from different hierarchical positions in these two companies. Data was also gathered through interviews with representatives from the companies, the Council of Engineering, the Engineering Education System and the Engineers Trade Unions. The findings show that the engineering profession in Brazil has shifted from its initial condition as a liberal profession to an organizational profession, with the country's industrial deployment. Both companies consider all salaried workers as employees, including managers. Hence they are subject to the company's general personnel policies. The multinational company controls labour more rigidly than the national company, as well as reserving its top positions for its home country's executives. Although no deskilling process was found, engineers of both companies performed simple work, which required less engineering knowledge than they had learned from school. Engineers have little autonomy, authority and participation in decision making and are subject to direct supervision, performance evaluation, time control, overtime work, productivity and to poor working conditions in the multinational company. The majority of the engineers supervised other workers without being in a managerial position. They found that to move into management, was a good way to improve their autonomy, authority, prestige, salary, status, power and professional pride. Despite ideological divisions between capital and labour, most of the engineers were unionised and saw unions as the right way to deal with the employer.

Relationship status and identity construction in heterosexual women:A discourse analytic and personal construct study

This thesis reports the findings of three studies examining relationship status and identity construction in the talk of heterosexual women, from a feminist and social constructionist perspective. Semi-structured interviews were conducted with 12 women in study 1 and 13 women for study 2, between the ages of twenty and eighty-seven, discussing their experiences of relationships. All interviews were transcribed and analysed using discourse analysis, by hand and using the Nudist 6 program. The resulting themes create distinct age-related marital status expectations. Unmarried women were aware they had to marry by a ‘certain age’ or face a ‘lonely spinsterhood’. Through marriage women gained a socially accepted position associated with responsibility for others, self-sacrifice, a home-focused lifestyle and relational identification. Divorce was constructed as the consequence of personal faults and poor relationship care, reassuring the married of their own control over their status. Older unmarried women were constructed as deviant and pitiable, occupying social purgatory as a result of transgressing these valued conventions. Study 3 used repertory grid tasks, with 33 women, analysing transcripts and notes alongside numerical data using Web Grid II internet analysis tool, to produce principle components maps demonstrating the relationships between relationship terms and statuses. This study illuminated the consistency with which women of different ages and status saw marriage as their ideal living situation and outlined the domestic responsibilities associated. Spinsters and single-again women were defined primarily by their lack of marriage and by loneliness. This highlighted the devalued position of older unmarried women. The results of these studies indicated a consistent set of age-related expectations of relationship status, acknowledged by women and reinforced by their families and friends, which render many unmarried women deviant and fail to acknowledge the potential variety of women’s ways of living.