A framework for predicting the non-visual effects of daylight - part I: photobiology-based model

This paper investigates the formulation of a modelling framework for the nonvisual effects of daylight, such as entrainment of the circadian system and maintenance of alertness. The body of empirical data from photobiology studies is now sufficient to start developing preliminary non-visual lighting evaluation methods for lighting design. Eventually, these non-visual effects have the potential to become a relevant quantity to consider when assessing the overall daylighting performance of a space. This paper describes the assumptions and general approach that were developed to propose a modeling framework for occupant exposure to non-visual effects of light, and presents a novel means of visualising the ‘circadian potential’ of a point in space. The proposed approach uses current outcomes of photobiology research to define – at this point static – threshold values for illumination in terms of spectrum, intensity and timing of light at the human eye. These values are then translated into goals for lighting simulation, based on vertical illuminance at the eye, that – ultimately – could become goals for building design. A new climate-based simulation model has been developed to apply these concepts to a residential environment. This will be described in Part 2 of this paper

A Physiological and Psychometric Evaluation of Human Subconscious Visual Response and Its Application in Health Promoting Lighting.

Subconscious vision is a recent focus of the vision science community, brought on by the discovery of a previously unknown photoreceptor in the retina dedicated to driving non-image-forming responses, intrinsically photosensitive retinal ganglion cells (ipRGCs). In addition to accepting inputs from rod and cone photoreceptors, ipRGCs contain their own photopigment, melanopsin, and are considered true photoreceptors. ipRGCs drive various non-image-forming photoresponses, including circadian photoentrainment, melatonin suppression, and pupil constriction. In order to understand more about ipRGC function in humans, we studied its sensitivity to light stimuli in the evening and day. First, we measured the sensitivity threshold of melatonin suppression at night. Using a protocol that enhances data precision, we have found the threshold for human melatonin suppression to be two orders of magnitude lower than previously reported. This finding has far-reaching implications since there is mounting evidence that nocturnal activation of the circadian system can be harmful. Paradoxically, ipRGCs are understimulated during the day. Optimizing daytime non-image-forming photostimulation has health benefits, such as increased alertness, faster reaction times, better sleep quality, and treatment of depression. In order to enhance ipRGC excitation, we aimed to circumvent adaptation (i.e. desensitization) of the photoresponse by using flickering instead of steady light. We find that properly timed flickering light enhances pupillary light reflex significantly when compared to steady light with 9-fold more energy density. Employing our findings, a new form of LED light is proposed to enhance subconscious visual responses at a typical indoor illuminance level. Using the silent substitution technique, a melanopsin-selective flicker is introduced into the light. A linear optimization algorithm is used to maximize the contrast of the subconscious, melanopsin-based response function while keeping conscious, cone-driven responses to the pulsing light fixed. Additional boundary conditions utilizing test color samples as an environmental mimic are introduced to limit the amount of perceived color change in a simulated environment. Two examples of lights are given to illustrate potential applications for general illumination and therapeutic purposes. For the lighting and electronics industry, we hope our study of subconscious-stimulative thresholds at night will better inform their design guidelines for health conscious products.PhDMacromolecular Science and EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/133226/1/garenv_1.pd

Change blindness: eradication of gestalt strategies

Arrays of eight, texture-defined rectangles were used as stimuli in a one-shot change blindness (CB) task where there was a 50% chance that one rectangle would change orientation between two successive presentations separated by an interval. CB was eliminated by cueing the target rectangle in the first stimulus, reduced by cueing in the interval and unaffected by cueing in the second presentation. This supports the idea that a representation was formed that persisted through the interval before being 'overwritten' by the second presentation (Landman et al, 2003 Vision Research 43149–164]. Another possibility is that participants used some kind of grouping or Gestalt strategy. To test this we changed the spatial position of the rectangles in the second presentation by shifting them along imaginary spokes (by ±1 degree) emanating from the central fixation point. There was no significant difference seen in performance between this and the standard task [F(1,4)=2.565, p=0.185]. This may suggest two things: (i) Gestalt grouping is not used as a strategy in these tasks, and (ii) it gives further weight to the argument that objects may be stored and retrieved from a pre-attentional store during this task

Towards early hemolysis detection: a smartphone based approach

Os especialistas em diagnóstico in vitro (IVDs) têm confiado maioritariamente na inspeção visual (ótica) manual e, em segundo lugar, em sensores óticos ou câmaras embutidas ou dispositivos médicos incorporados que suportam o exame da qualidade da amostra na fase pré-analítica. Com o aumento dos volumes de amostras para serem processadas e dos respetivos dados complexos gerados por esse processamento, aquelas técnicas tornaram-se cada vez mais difíceis de utilizar, ou os respetivos resultados não ficam imediatamente disponíveis. Para superar as complexidades impostas por tais técnicas tradicionais, o aumento do uso de dispositivos móveis e algoritmos de processamento de imagem no setor de saúde abriu caminho para a constituição de novos casos de uso baseados em análises móveis de amostras, pois fornecem uma interação simples e intuitiva com objetos gráficos familiares que são mostrados no ecrã dos smartphones. As interfaces gráficas e as técnicas de interação suportadas por dispositivos móveis podem pois proporcionar ao especialista em IVD uma série de vantagens e valor agregado devido à maior familiaridade com estes dispositivos e à grande acessibilidade que evidenciam atualmente, tendo o potencial de facilitar as análises de amostras. No entanto, o uso sistemático de dispositivos móveis no setor da saúde encontra-se ainda numa fase muito incipiente, em particular na área de IVD. Nesta tese, propõe-se conceber e discutir a arquitetura, a conceção e a implementação de um protótipo de uma aplicação móvel para smartphone (designada por "HemoDetect") que implementa um conjunto sugerido de algoritmos, interfaces e técnicas de interação que foram desenvolvidos com o objetivo de contribuir para a compreensão de técnicas mais eficientes para ajudar a detetar a hemólise, um processo que designa a rotura de glóbulos vermelhos (eritrócitos) e libertação do respetivo conteúdo (citoplasma) para o fluído circundante (por exemplo, plasma sanguíneo), complementando-as com estatísticas e medições de laboratório, mostrando a utilização de um protótipo durante experiências, permitindo assim chegar-se a um conceito viável que permita apoiar eficazmente a deteção precoce de hemólise.In Vitro Diagnostics (IVDs) specialists have been firstly relying on manual visual (optical) inspection and, secondly, on optical sensors or cameras embedded or built-in medical devices which support the examination of sample quality in pre-analytical phase. With increasing sample processing volumes and their generated complex data, these techniques have become increasingly difficult or results are not readily available. In order to overcome the complexities posed by these traditional techniques, the increased usage of mobile devices and algorithms in the healthcare industry paves the way into shaping new use cases and discovery of mobile analysis of samples, as they provide a user-friendly and familiar interaction with objects displayed on their screens. The interfaces and interaction techniques rendered by mobile devices, bring, to the IVD specialist, a number of advantages and added value due to increased familiarity with the devices or their accessibility, which is made easier. However, they are at the beginning of their journey in the healthcare industry, in particular in the IVD and point-of-care areas. In this thesis, the proposal is to discover and discuss the architecture, design and implementation of a smartphone prototype app (called “HemoDetect”) with its algorithms, interfaces and interaction techniques which was developed to help detect hemolysis which represents the rupture of red blood cells (erythrocytes) and release of their contents (cytoplasm) into surrounding fluid (e.g. blood plasma), and complementing it with from-the-lab statistics and measurements showing its utilization during experiments, which ultimately may be a feasible concept that could support early hemolysis detection.Les spécialistes du diagnostic in vitro (DIV) se sont d'abord appuyés sur l'inspection visuelle (optique) manuelle et, ensuite, sur des capteurs optiques ou des caméras intégrées ou intégrées à des dispositifs médicaux qui facilitent l'examen de la qualité des échantillons en phase pré-analytique. Avec l'augmentation des volumes de traitement des échantillons et des données complexes générées, ces techniques sont devenues de plus en plus difficiles ou les résultats ne sont pas facilement disponibles. Afin de surmonter les complexités posées par ces techniques traditionnelles, l'utilisation croissante des appareils mobiles et des algorithmes dans le secteur de la santé ouvre la voie à la définition de nouveaux cas d'utilisation et à la découverte d'analyses d'échantillons mobiles, car ils fournissent une interaction conviviale et familière. avec des objets affichés sur leurs écrans. Les interfaces et les techniques d'interaction rendues par les appareils mobiles apportent au spécialiste des dispositifs de DIV un certain nombre d'avantages et de valeur ajoutée en raison d'une familiarisation accrue avec les appareils ou de leur accessibilité, ce qui est facilité. Cependant, ils sont au début de leur parcours dans le secteur de la santé, en particulier dans le domains des DIV et point-of-care. Dans cette thèse, la proposition est de découvrir et de discuter de l’architecture, de la conception et de la mise en oeuvre d’une application pour smartphone (appelée «HemoDetect») avec ses algorithmes, interfaces et techniques d’interaction, qui a été développée pour aider à détecter l’hémolyse qui représente une rupture des globules rouges (érythrocytes) et la libération de leur contenu (cytoplasme) dans le liquide environnant (par exemple, le plasma sanguin), en le complétant par des statistiques de laboratoire et des mesures montrant son utilisation au cours des expériences, ce qui pourrait finalement être un concept réalisable qui pourrait permettre une détection précoce de l'hémolyse

Traffic sign recognition based on human visual perception.

This thesis presents a new approach, based on human visual perception, for detecting and recognising traffic signs under different viewing conditions. Traffic sign recognition is an important issue within any driver support system as it is fundamental to traffic safety and increases the drivers' awareness of situations and possible decisions that are ahead. All traffic signs possess similar visual characteristics, they are often the same size, shape and colour. However shapes may be distorted when viewed from different viewing angles and colours are affected by overall luminosity and the presence of shadows. Human vision can identify traffic signs correctly by ignoring this variance of colours and shapes. Consequently traffic sign recognition based on human visual perception has been researched during this project. In this approach two human vision models are adopted to solve the problems above: Colour Appearance Model (CIECAM97s) and Behavioural Model of Vision (BMV). Colour Appearance Model (CIECAM97s) is used to segment potential traffic signs from the image background under different weather conditions. Behavioural Model of Vision (BMV) is used to recognize the potential traffic signs. Results show that segmentation based on CIECAM97s performs better than, or comparable to, other perceptual colour spaces in terms of accuracy. In addition, results illustrate that recognition based on BMV can be used in this project effectively to detect a certain range of shape transformations. Furthermore, a fast method of distinguishing and recognizing the different weather conditions within images has been developed. The results show that 84% recognition rate can be achieved under three weather and different viewing conditions

Flowers through insect eyes: the contribution of pollinator vision to the evolution of flower colour

PhDFlowers’ colours are an essential element of their ability to attract visits from pollinators. However, the colours as they appear to human observers can differ substantially from their appearance to insect pollinators, and so it is essential to consider pollinator vision in any study of the ecology of flower colour. In this thesis I describe how I have overseen the development of an online database to provide accurate information on floral spectral reflectance measured without human observational bias. This resource allows a more accurate consideration of flower colours in future studies, and permits investigations of flower colours within and across habitats. Using the records in this database, I analysed flowers from two European habitats for spatial or temporal changes, modelling the colours according to insect visual perception. I discovered that the insect-colour composition of the plant communities does not change either along an altitudinal gradient or throughout the year. These novel and ecologically-relevant analyses contradict previous observational studies, but support the theory of a pollination “market” in which flowers compete for pollinator visitation. I then describe my experimental investigations into the visual capabilities of two pollinators and how this may relate to what colours of flowers they visit. Firstly I study the foraging behaviour of bees under spatially inconsistent illumination and how this impacts on their choice behaviour. I revealed patchy light can have measurable effects on bee foraging behaviour: they intentionally choose familiar over unfamiliar illumination, which may impact on the flowers they visit in complex natural environments. Secondly, I detail the new evidence for a red-sensitive photoreceptor in South African monkey beetles, a major pollinator in a habitat containing many longwavelength- reflecting flowers, which are not classically “attractive” to bees. Throughout this thesis, I explore how pollinator vision has shaped the evolution of flower colours in different contexts.Biotechnology and Biological Science Research Council. Royal Botanical Gardens Kew (BBS/S/L-2005/12155A