Wavefront sensing using a graphical user interface

We present an open wavefront sensor setup assisted with MATLAB programming to be used to teach the operating principle of Shack-Hartmann aberrometry. A new Graphical User Interface (GUI) has also been developed to determine the wavefront parameters from experimental measurements and the associated aberrations, which is a fundamental issue in Optical Engineering. From a didactical point of view, the proposed method allows students to interpret the results in a visual and heuristic way.Contract grant sponsor: Ministerio de Economia y Competividad; Contract grant number: FIS2011-23175; Contract grant sponsor: Generalitat Valenciana; Contract grant number: PROMETEOII/2014/072; Contract grant sponsor: Universitat de Valencia; Contract grant number: UV-SFPIE_DINV14-222801Ferrando Martín, V.; Remón Martín, L.; Pons Martí, A.; Furlan, WD.; Monsoriu Serra, JA. (2016). Wavefront sensing using a graphical user interface. Computer Applications in Engineering Education. 24(2):255-262. https://doi.org/10.1002/cae.21703S25526224

Structured illumination microscopy for in-vivo human retinal imaging: a theoretical assessment

Structured illumination microscopy applied to in-vivo retinal imaging has the potential to provide a low-cost and powerful diagnostic tool for retinal disease. In this paper the key parameters that affect performance in structured illumination ophthalmoscopy are studied theoretically. These include the number of images that need to be acquired in order to generate a sectioned image, which is affected by the non-stationary nature of the retina during acquisition, the choice of spatial frequency of the illuminating sinusoid, the effect of typical ocular aberrations on axial resolution and the nature of the sinusoidal pattern produced by the illumination system. The results indicate that structured illumination ophthalmoscopy can be a robust technique for achieving axial sectioning in retinal imaging without the need for complex optical systems

Editorial: From Exceptional Cases to Everyday Abuses: Labour exploitation in the global economy

This article introduces a special issue on economic systems and everyday abuses of labour rights. In recent decades, neoliberal policies have transformed both the world economy and the world of work. Hard-won rights and protections have been eroded by deregulation, outsourcing, and subcontracting. New forms of unstable, isolated, and insecure work have emerged. This introduction examines the driving forces behind the increasing prominence of precarious work, the accelerating role of migrant labour within global economic systems, and the political relationship between everyday abuses and forms of severe exploitation which have recently come to be defined as human trafficking and modern slavery. We argue that a singular focus upon individual cases of extreme exploitation is unlikely to be effective, and can also draw attention away from the larger systems, interests, and abuses that are associated with the smooth and regular operations of the global economy. We also suggest that at least some of the energies which have recently been expended debating the contentious category of ‘modern slavery’ could be usefully redirected towards lower profile interventions concerned with worker and migrant rights. There are never going to be simple or straightforward solutions to labour abuses, so it is necessary to take many bumpy paths simultaneously, with small steps forward and some steps backward

Confronting root causes: forced labour in global supply chains

Excerpt It is by now widely recognised that effectively tackling forced labour in the global economy means addressing its ‘root causes’. Policymakers, business leaders and civil society organisations all routinely call for interventions that do so. Yet what exactly are these root causes? And how do they operate? The two most commonly given answers are ‘poverty’ and ‘globalisation’. Although each may be foundational to forced labour, both terms are typically used in nebulous, catch-all ways that serve more as excuses than explanations. Both encompass and obscure a web of decisions and processes that maintain an unjust status quo, while being used as euphemisms for deeper socio-economic structures that lie at the core of the capitalist global economy. The question thus becomes: exactly which aspects of poverty and globalisation are responsible for the endemic labour exploitation frequently described with the terms forced labour, human trafficking or modern slavery? Which global economic processes ensure a constant and low-cost supply of highly exploitable and coerced workers? And which dynamics trigger a demand among businesses for their exploitation, making it possible for them to profit from it? This 12-part report is an attempt to answer these questions in a rigorous yet accessible way. With it, we hope to provide policymakers, journalists, scholars and activists with a road map for understanding the political economy of forced labour in today’s “global value chain world”

Processing blur of conflicting stimuli during the latency and onset of accommodation

The accommodative response (AR) to changes in dioptric accommodative stimulus (AS) during the latency period and onset of accommodation was investigated. Participants monocularly observed one period of a square wave in AS, with a 2-D baseline and mean, and amplitude 1 D or 2 D; the period of the square wave ranged from 0.10 s to 1.00 s; both increases and decreases were used for the first step in AS. At periods of 0.30 s and longer, accommodation was found to respond to both levels of the stimulus. Rapid retinal monitoring appeared to be taking place for such stimuli. The amplitudes of peaks in AR did not usually depend on whether a particular level of AS occurred first or second, but for 8/40 conditions, a significant difference was found, with a stronger response when the level of AS occurred second. Null or incorrect responses were also observed in many trials, possibly linked with the natural microfluctuations of accommodation. Minimum response times to the changes in AS were observed, which increased with decreasing period of the AS. The time interval between peaks in the AR decreased with decreasing period of the AS. The findings were consistent with a parallel processing model previously proposed for saccades, where input from a later change in stimulus may enter an element of the control system when that element has finished processing an earlier change. More than one change in stimulus may therefore be passing through the multi-element control system at a time