Sparkle is a visual texture which appearance basically consists of very bright spots randomly distributed over a darker background. The effect is more apparent to the observer when one of the contributors (sample, observer, illumination) is moved, meaning it is a dynamic effect. While the characterization and measurement of sparkle has been an important topic of research during the past years, the focus has been solely around the static component of it, the dynamic aspect of sparkle has been left out of the discussion. This is somewhat reasonable since the dynamic attribute bases itself on the perception and measurement of static sparkle. The dynamic aspect of sparkle, or “living sparkle” can be described as the variation of its appearance over a given angular distance. Nonetheless, both effects are without doubt related and perhaps together they provide the key to finding the absolute characterization of sparkle. In this work we aim to dive into both aspects. First, the setup of a goniometric system with a color camera was carried out, obtaining a high spatial and angular resolution. Second, measurements of commercial and self-manufactured sample sets were performed, and an analysis algorithm was developed. The algorithm provided a wide range of parameters for different thresholding methods. These methods were put to test when the results were correlated with the visual assessment of a group of 9 samples under one illumination/observation geometry, obtaining the correlation factors for all methods and parameters. The combination of thresholding method and parameter obtained an R2 > 0.9, implying a strong connection with the visual experience. The threshold applied was always fixed at the same value and the parameter (“S_Values”) represented the brightness of the pixels, indicating that the brightness of the sample is the most influential attribute for the perception of sparkle. Then, this same methodology was applied to the rest of the samples in this study (71 total), for the geometries in between 71.2 and 11.2 degrees in 5 degrees steps. The physical parameters of the self-manufactured samples were also used to test the correctness of the algorithm. The results broadly matched the expected values of intensity and particle size. In addition, the algorithm measured the angular variability of the samples though the angular visibility of the sparkle spots. The wider the visible range, the more invariant the sample, and the less apparent the sparkle effect. This work proposes an innovative way of measuring sparkle in its dynamic and static components, a methodology and measurands to do so are proposed and contrasted to visually assessed samples.

Influence of nitrogen (N) deficiency on castor cv. ‘Hale’ growth, physiology, and leaf reflectance properties were investigated. Treatments imposed were complete Hoagland’s nutrient solution (control, 100N), reduced N to 20% of the control (20N) and withheld N from the solution (0N) from 34 to 66 days after sowing (DAS) in 12-L pots grown out doors. N deficiency significantly reduced leaf area, chlorophyll and photosynthesis resulting lower total biomass. Leaf and stem growth rates were more sensitive to leaf N concentration than photosynthesis and leaf addition rates. N deficiency stress increased leaf reflectance at R555 and R715 nm and caused a red-edge shift to shorter wavelengths. Reflectance ratios of R455/R605 and R505/R605 nm was highly correlated with leaf N on weight (r2 = 0.93) and area-based (r2 = 0.90) estimations, respectively. Similarly, reflectance ratio R635/R505 was highly correlated with chlorophylls (r2 = 0.94). The N-specific wavebands and functional relationships between leaf N and growth and developmental processes would be useful for rapid and non-destructive estimation of leaf N and growth rates of castor.

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京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第19411号 / 工博第4127号 / 新制||工||1636(附属図書館) / 32436 / 京都大学大学院工学研究科都市社会工学専攻 / (主査)教授 小池 克明, 教授 田村 正行, 教授 三ｹ田 均 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

Complete resection is correlated to better patient outcome in aggressive cancers such as glioblastoma. Optical biopsy refers to a family of techniques utilizing optical properties of living targets to make diagnoses where a biopsy would conventionally be used. Such a technology can potentially guide neurosurgeons in removing glioblastomas. Diffuse reflectance (DR) and Time-resolved fluorescence (TRF) have previously been investigated for their ability to measure biomarkers indicative of cancer. One of the difficulties faced in using TRF as a diagnostic tool is that multiple endogenous fluorophores will simultaneously contribute to the signal. This makes it difficult to attribute fluorescence lifetimes or spectral changes to one type of molecule in the tissue. This thesis focuses on the challenge of separating the components in a TRF measurement and their fractional contributions. A DR-TRF instrument was designed and built and characterized using fluorescent dyes. An orthonormal basis deconvolution method combined with a Fourier-domain method were tested for their ability to unmix fluorescent components in a hyperspectral TRF measurement. This method was tested on dye mixtures and retrieved fluorescence lifetimes of 4.6±0.4 ns and 2.7±0.2 ns in a mixture of Fluorescein and Coumarin-6 at concentrations of 5 μM each. It was also tested on an ex-vivo brain tissue where the fluorescence was approximated as a sum of 2 components. / Thesis / Master of Applied Science (MASc)