Digital Image Processing And Metabolic Parameter Linearity To Noninvasively Detect Analyte Concentration

Spectroscopy is the scientific technique of quantifying and measuring electromagnetic, or light, reflectance or absorption. Atoms emit and/or absorb light when light passes through. The excitations provide specific energy signatures that relate to the element that is emitting or absorbing the light. Non-invasive biosensors monitor physical health properties such as heart rate, oxygen saturation, and tissue blood flow as a result of spectroscopy. Several attempts have been made to non-invasively detect metabolic chemical, or analyte, concentration with various spectroscopic techniques. The primary limitation is due to signal-to-noise ratio. This research focuses on a unique method that combines emission spectroscopy and machine learning to non-invasively detect glucose and other metabolic analyte concentrations. Artificial neural network is applied to train a predictive model that enables the remote sensing capability. The data acquisition requires capturing digital images of the spectral reflectance. Image processing and segmentation determines discrete variables that correlate with the metabolic analytes. The clinical trial protocol includes n=90 subjects, and a venipuncture comprehensive metabolic panel blood test within two minutes prior to a non-invasive spectral reading. Results indicate a strong correlation between the spectral system and the clinical gold standard, relative to metabolic analyte concentration

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

Response normalization and blur adaptation:data and multi-scale model

Adapting to blurred or sharpened images alters perceived blur of a focused image (M. A. Webster, M. A. Georgeson, & S. M. Webster, 2002). We asked whether blur adaptation results in (a) renormalization of perceived focus or (b) a repulsion aftereffect. Images were checkerboards or 2-D Gaussian noise, whose amplitude spectra had (log-log) slopes from -2 (strongly blurred) to 0 (strongly sharpened). Observers adjusted the spectral slope of a comparison image to match different test slopes after adaptation to blurred or sharpened images. Results did not show repulsion effects but were consistent with some renormalization. Test blur levels at and near a blurred or sharpened adaptation level were matched by more focused slopes (closer to 1/f) but with little or no change in appearance after adaptation to focused (1/f) images. A model of contrast adaptation and blur coding by multiple-scale spatial filters predicts these blur aftereffects and those of Webster et al. (2002). A key proposal is that observers are pre-adapted to natural spectra, and blurred or sharpened spectra induce changes in the state of adaptation. The model illustrates how norms might be encoded and recalibrated in the visual system even when they are represented only implicitly by the distribution of responses across multiple channels

Ambiguous Perception and Selective Attention - Competitive Processes in Complex Scenarios

Unser visuelles System wird jeden Tag mit komplexen und mehrdeutigen Szenen und Ereignissen konfrontiert. Diese Informationen müssen weitergeleitet, gefiltert und verarbeitet werden, um uns ein angemessenes Verhalten in unserer Umwelt zu ermöglichen. Visuelle Wahrnehmung ist dieser Prozess der Interpretation auf der Basis von Informationen, die im sichtbaren Licht enthalten sind. Die Herausforderungen, denen sich unsere Wahrnehmung stellen muss, sind vielfältig. Fehlende Informationen erschweren die Interpretation von Situationen und das Erlangen einer kohärenten Sinneserfahrung, insbesondere da ein und dieselbe visuelle Szene oftmals verschiedene Interpretationen zulassen kann. Diese Doktorarbeit umfasst fünf Studien, die sich mit der Wahrnehmung von mehrdeutigen oder komplexen Reizen unter Laborbedingungen und in realen Situationen befassen. Hierbei wurden sowohl gesunde Probanden als auch Patienten mit neurodegenerativen Krankheiten untersucht und ein neuronales Netzwerk für das bessere Verständnis der zugrundeliegenden Verarbeitungsmechanismen im Gehirn herangezogen

Correction and control of ocular aberrations with adaptive optics : effects on human vision

El objetivo de esta tesis doctoral es la comprensión de la relación entre la óptica de la imagen que se proyecta en la retina (en particular, la degradación impuesta por las aberraciones ópticas de alto orden) y la calidad visual. Se ha llevado a cabo el desarrollo de un nuevo sistema de Óptica Adaptativa, que incluye un sensor de frente de onda tipo Hartmann-Shack y un espejo deformable, implementando vías de psicofísica para la medida de la función visual y percepción neuronal bajo control de las aberraciones oculares mediante el espejo deformable. En esta tesis, se presenta una serie de estudios psicofísicos desarrollados para investigar el efecto de la aberraciones sobre la visión humana y la adaptación neuronal a las aberraciones oculares y también para demostrar la correlación entre la codificación interna del emborronamiento y el emborronamiento impuesto por las aberraciones de alto orden en términos de magnitud y orientació

Aerospace Medicine and Biology. A continuing bibliography with indexes

This bibliography lists 244 reports, articles, and other documents introduced into the NASA scientific and technical information system in February 1981. Aerospace medicine and aerobiology topics are included. Listings for physiological factors, astronaut performance, control theory, artificial intelligence, and cybernetics are included

La perception d'attributs visuels de premier et deuxième ordres

Thèse numérisée par la Division de la gestion de documents et des archives de l'Université de Montréal

Aberraciones cromáticas, monocromáticas y diseños multifocales: interacción e impacto en la visión

Tesis inédita de la Universidad Complutense de Madrid, Facultad de Óptica y Optometría, leída el 21/01/2021An important part of the information that we receive from the world is through the sense of vision: the eye projects images on the retina, which transforms them into nerve impulses that reach the neuronal cortex, where these impulses are interpreted. However, the images projected onto the retina are not perfect, as they are affected by diffraction, scattering, and aberrations, which degrade contrast and decrease the resolution limit of the eye. To understand the effect of aberrations on vision, it is necessary to develop technologies and experiments that allow objectively and subjectively assess their interaction. In this sense, Adaptive Optics (AO) has played an important role in increasing our knowledge about the neural processes of vision, since AO can be used to measure, correct and induce aberrations. Understanding what role aberrations play and what their impact is on vision will help to develop better correction designs for the eye. The manipulation of the wavefront using AO also allows to induce a certain visual correction, so it can be used as a basis for visual simulators. As AO allows studying a new lens design or comparing across different lens designs even before they are manufactured, this is an excellent tool to test and improve optical corrections before they are implanted in the eye of a patient. Different technologies including deformable mirrors (DM), spatial light modulators (SLM), or temporal multiplexing by an optotunable lens (SimVis), are currently being validated and launched into the clinical practice. In this thesis, AO technologies have been implemented and used both to study the effect of aberrations and to cross-validate different simulator modalities...Una importante parte de la información que recibimos del mundo lo hacemos a través del sentido de la visión: el ojo proyecta las imágenes en la retina, la cual las transforma en impulsos nerviosos que llegan hasta el córtex neuronal, donde se interpretan estos impulsos. Sin embargo, las imágenes proyectadas en la retina no son perfectas, ya que están afectadas por la difracción, la dispersión y las aberraciones, que degradan el contraste y reducen el límite de resolución del ojo. Para entender el efecto de las aberraciones en la visión es necesario desarrollar tecnologías y experimentos que permitan valorar objetiva y subjetivamente su interacción. En este sentido, la Óptica Adaptativa (AO) ha jugado un papel importante en el incremento de nuestro conocimiento acerca de los procesos neuronales de la visión, ya que la AO se puede utilizar para medir, corregir e inducir aberraciones. Comprender qué papel juegan las aberraciones y cuál es su impacto en la visión, ayudará a desarrollar mejores diseños de corrección para el ojo, sin embargo, aún no se entiendo completamente. La manipulación del frente de onda mediante AO permite, además, inducir una cierta corrección visual, por lo que se puede utilizar como base de simuladores visuales. Estudiar un nuevo diseño o comparar varios diseños entre ellos antes incluso de que sean fabricados, plantea la AO como una excelente herramienta para probar y mejorar una corrección antes de que sea implantada. Para ello, diferentes tecnologías como los espejos deformables, los Moduladores Espaciales de Luz (SLM), la multiplexación temporal inducida por una lente optoajustable (SimVis), están siendo en la actualidad validados y lanzados a la práctica clínica. En esta tesis se ha utilizado la AO tanto para estudiar el efecto de las aberraciones como comparar diferentes simuladores visuales...Fac. de Óptica y OptometríaTRUEunpu

IMPACT OF NEW LIGHTING TECHNOLOGIES ON OFFICE ERGONOMICS

The goal of this study was to find the impact of cutting-edge light-emitting diodes (LED) lighting technologies on the office ergonomics in modern offices. An experiment was conducted in a windowless office at the University of Kansas. This experiment used four test conditions with two levels of light sources (LED and fluorescent lamps) and two levels of lighting control (with/without lighting control). A total of 30 subjects with an average age of 21.6 and eyesight of 20/20 and 20/16 participated in this experiment. Subjects performed typing tasks and color matching tasks under each one of four test conditions. Subjective evaluation of lighting quality and task satisfaction were collected using a questionnaire. High Dynamic Range (HDR) photography was used as a new approach of light measurement in offices. The results revealed that LED lighting had more consistent color rendering performance than fluorescent lighting, and also led to better typing task satisfactions. LED lighting could reduce the lighting power consumption (by up to 65.5% in this study) without any negative impact on office ergonomics. Introduction of individual lighting control could lead to better satisfaction toward the lighting quality and higher savings in lighting power consumption