Artifacts in polarimeters are apparent polarization features which are not real but result from the systematic errors in the polarimeter. The polarization artifacts are different between division of focal plane, spectral, and time modulation polarimeters. Artifacts result from many sources such as source properties, micropolarizer arrays, coatings issues, vibrations, and stress birefringence. A modeling examples of polarization artifacts due to a micro-polarizer array polarimeter is presented.

Following the crash of a Norwegian Hercules aircraft on Rabots glaciär in the Kebnekaise mountain range in 2012, a field campaign was initiated in order to assess the fate of the hydrocarbon pollution in the system. It is hypothesized that soluble components of the aircraft fuel will be transported within the glacial meltwater. This thesis focuses on constraining the likely transit time and dispersion of the meltwater as a proxy for potential pollution pathways. Therefore, the hydrologic configuration of Rabots glaciär was studied during the ablation season 2013 by means of dye tracing experiments and discharge monitoring in the proglacial stream. The analyses of the dye return curves and stream monitoring suggest that Rabots glaciär exhibits a widely efficient drainage system towards the end of the ablation season, but with analyses revealing heterogeneity in the drainage system form. The seasonal evolution of efficiency was also assessed, showing an increase over time, although was hampered by early onset of melting before the field season began. There are different hydrological configurations on the north and south side of the glacier, possibly influenced by shading. The system on the north side is routing meltwater along the glacier bed over a long distance as indicated by the turbid outlet stream. Water routing on the southern side likely occurs through englacial channels. This configuration may be influenced by the thermal regime and distribution of cold surface layers. It has further been revealed that both systems are likely to be disconnected from each other. Pollution that is transported with the meltwater down from the crash site on the southern side does not reach the drainage system on the northern side. Besides revealing potential pathways for soluble hydrocarbon pollutants, this case study contributes to the previously very limited knowledge of Rabots glacial hydrology, and our general understanding of polythermal glacier hydrology.

The point spread function (PSF) for astronomical telescopes and instruments depends not only on geometric aberrations and scalar wave diffraction, but also on the apodization and wavefront errors introduced by coatings on reflecting and transmitting surfaces within the optical system. Geometrical ray tracing provides incomplete image simulations for exoplanet coronagraphs with the goal of resolving planets with a brightness less than 10<^>-9 of their star located within 3 Airy disk radii. The Polaris-M polarization analysis program calculates uncorrected coating polarization aberrations couple around 10<^>-5 light into crossed polarized diffraction patterns about twice Airy disk size. These wavefronts not corrected by the deformable optics systems. Polarization aberrations expansions have shown how image defects scale with mirror coatings, fold mirror angles, and numerical aperture.

To stem the spread of infectious diseases, epidemiologists use contact tracing interviews to identify individuals who may need treatment or, if indicated, quarantine or isolation. Given the high stakes, the most exhaustive list of potentially infected contacts must be reported. However, standard contact tracing procedures may fail to extract the most complete report possible from sick individuals. One of the most reliable methods for maximizing recall is the Cognitive Interview (CI). The CI uses several techniques grounded in psychological theory and was expected to increase the number of contacts listed during contact tracing interviewing compared to a standard contact tracing interview. In Study One, participants imagined they were infected with meningococcal meningitis, and reported every person with whom they had physical contact, shared saliva, or lived with over the previous three days (i.e., at a high risk for developing meningococcal meningitis). Participants were interviewed with either a CI or a standard interview. Results suggested that the CI generated 35% more total contacts listed, however, when examining only the contacts listed who would be at a high risk of meningococcal meningitis there was no significant difference between the CI and the standard interview. Study Two followed the same procedure as that in Study One, but added a manipulation of cognitive resources intended to model impairment experienced by individuals who are interviewed while suffering from acute illness. Participants completed (or did not complete) a working memory impairment task (pressed a spacebar on a keyboard every time 7 seconds passed) while reporting their physical contacts during either a CI or a standard interview. Results clearly demonstrated a superiority of the CI in generating both more total contacts and more contacts at a risk of meningococcal meningitis than the standard interview. However, when the working memory impairment task was completed, the CI generated no more contacts than the standard interview. Findings have serious implications for contact tracing interviewing for infectious diseases such as Ebola and Zika. In light of the findings, we recommend the CI be considered as an alternative to the typical contact tracing interview, particularly if the interviewee is not cognitively impaired.

We investigate to which degree one could trace Bitcoin transactions and characterize purchasing behavior of online anonymous marketplaces by exploiting side channels. Using a list of addresses found by the FBI on Silk Road servers, and information on the marketplace's official guides, we infer the role played by each address in the list and classify them based on heuristics. We then attempt to trace Bitcoin transactions and show that the anonymity set size is greatly reduced using product review data and the address classification performed on the previous step. Finally, using clustering techniques based on transaction graph analysis, we assign addresses into user wallets, then group these wallets together based on spending patterns, to be able to characterize purchasing behavior.

It was hypothesized that superparamagnetic nanoparticles encapsulated in a silica shell with a fluorescent dye could be functionalized with axonal tracers and could be used for serial, non-invasive imaging with magnetic resonance imaging (MRI) for axon tract tracing. Nanoparticles functionalized with amine, octadecyl, silica, and biotinylated dextran amine were manufactured and characterized with MRI, scanning electron microscopy, and UV-visible, infrared, and fluorescence spectroscopy. Nanoparticle concentrations of 10 mM were not toxic to adult rat neural progenitor cells (NPCs) and labeled approximately 90% of cells. Nanoparticles were assessed for anterograde and retrograde tract tracing in adult rat models. With MRI and microscopy, the nanoparticles did not appear to trace axons but did provide an MRI signal for up to 3 weeks post implantation. While functionalized nanoparticles did not appear to trace axons, they are not toxic to NPCs and may be used as a MRI contrast agent in the neural axis.

京都大学 / 0048 / 新制・課程博士 / 博士(人間健康科学) / 甲第21706号 / 人健博第72号 / 新制||人健||5(附属図書館) / 京都大学大学院医学研究科人間健康科学系専攻 / (主査)教授 澤本 伸克, 教授 木下 彩栄, 教授 渡邉 大 / 学位規則第4条第1項該当 / Doctor of Human Health Sciences / Kyoto University / DFAM

<p>Cover cropping is an effective management practice for reducing nitrogen (N) losses to the environment from agriculture fields in the Midwest. Cereal rye (CR; <i>Secale cereale L</i>.) and hairy vetch (HV; <i>Vicia villosa Roth</i>) are two of the most common cover crop species grown in the region. However, limited cover crop adoption in the region is partly due to a dearth of knowledge addressing the effect of cover crops on nitrogen cycling and grain production within corn and soybean conservation cropping systems. The following studies were designed to address knowledge gaps in the current literature regarding the rate, quantity, and timing of cover crop residue C and N release; the fate of CR N following termination; and the effects of cover crops specifically on soybean growth, N assimilation, and yield. Data from this study revealed that growers should be aware that cover crop nutrient release may result in a “tug-of-war” between the soil microbiome and cash crops for soil inorganic-N. Additionally, we observed that CR N is used minimally by the subsequent crop; thus, growers should value CR N as a long-term benefit, such as building SOM. Finally, we found that added pressure from CR during early soybean growth may reduce soybean resilience, and in a wet year result in yield loss.</p>

Channel State Information (CSI) refers to a set of measurements used to characterize a radio communication link. Radio infrastructure collects CSI and derives useful metrics that indicate changes to modulation and coding to be made to improve the link performance (e.g. throughput, reliability). The CSI, however, has a wider potential use. It contains an environment-specific signature that can be used to extract information about users’ position and activity. In our work, we explore the problem of proximity estimation, which consists of identifying how close a pair of devices are to each other. By assuming that Cellular Base Stations (BSs) are distributed spatially according to a Poisson Point Process (PPP), and that the channel is under Rayleigh fading, we were able to probabilistically model radio measurements and use Bayesian inference to estimate the separation between two devices given their measurements only. We first explore a shadowless channel model, then we investigate how spatially-correlated shadowing can prove useful for estimation. For both cases, Bayesian estimators are proposed and tested through simulations. We also perform experiments and evaluate how well the estimators fit to actual data.

Natural gas and oil from characteristically complex unconventional reservoirs, such as organic shale, tight gas and oil, coal-bed methane; are transforming the global energy market. These conventional reserves exist in complex geologic formations where conventional seismic techniques have been challenged to successfully image the subsurface. To acquire maximum benefits from these unconventional reserves, seismic anisotropy must be at the center of our modeling and inversion workflows. I present algorithms for fast traveltime computations in anisotropic media. Both ray-based and finite-difference solvers of the anisotropic eikonal equation are developed. The proposed algorithms present novel techniques to obtain accurate traveltime solutions for anisotropic media in a cost-efficient manner. The traveltime computation algorithms are then used to invert for anisotropy parameters. Specifically, I develop inversion techniques by using diffractions and diving waves in the seismic data. The diffraction-based inversion algorithm can be combined with an isotropic full-waveform inversion (FWI) method to obtain a high-resolution model for the anellipticity anisotropy parameter. The inversion algorithm based on diving waves is useful for building initial anisotropic models for depth-migration and FWI. I also develop the idea of 'effective elliptic models' for obtaining solutions of the anisotropic two-way wave equation. The proposed technique offers a viable alternative for wavefield computations in anisotropic media using a computationally cheaper wave propagation operator. The methods developed in the thesis lead to a direct cost savings for imaging and inversion projects, in addition to a reduction in turn-around time. With an eye on the next generation inversion methods, these techniques allow us to incorporate more accurate physics into our modeling and inversion framework.