INTRODUCTION: The diagnosis and treatment of endodontic infections is a multi-step fact gathering process, with the gold standard of periapical lesion diagnosis being histological biopsy. With common diagnoses, such as periapical granulomas and radicular cysts, representing the bulk of biopsies, the possibility of a less invasive method of lesion identification ought to be examined. In recent years Cone Beam Computed Tomography (CBCT) imaging has been proposed as a potential diagnostic tool for periapical diagnosis, but this theory requires further testing and data in order to verify its appropriateness. OBJECTIVE: The aim of this study was to evaluate six criteria used for assessing periapical lesions of teeth seen on CBCT scan from the textbook Oral Radiology White and Pharoah. MATERIAL AND METHODS: Three blinded endodontists observed radiographic features of oral periapical lesions of teeth previously diagnosed as either radicular cysts or periapical granulomas via histological biopsy. All lesions had previously been scanned via CBCT, and endodontic apical surgery was performed allowing for a pathology sample of the lesion. The observers viewed 40 CBCT and 40 corresponding periapical (PA) radiographic images, all randomized, and reported which of the six criteria (Location- apex of tooth, periphery- corticated border, shape- curved or circular, internal structure- radiolucent, effects on surrounding structures- displace or resorb roots, corticated plate perforation- present) were present in the scans. Data was analyzed using a Logistical Regression Fleiss Kappa statistic with a 95% confidence level. RESULTS: CBCT cyst showed no agreement between examiners criteria selected to statistical significance. The most selected criteria by all examiners were shape and internal structure. PA radiographic Cyst showed moderate agreement for ‘Location’ and ‘Periphery’ and substantial agreement on ‘none’ criteria. The most selected criteria by all examiners were internal structure and location. CBCT Granuloma showed moderate agreement for ‘location’ and perfect agreement for ‘none’. The most selected criteria by all examiners were shape, location, and internal structure. PA radiographic Granuloma showed substantial agreement for ‘periphery’ and moderate agreement for internal structure (radiolucency). The most selected criteria by all examiners were location, and occasionally shape and internal structure. Logistic regression of selected criteria shows with each additional criteria present on each lesion the chance of the lesion being a granuloma decreases 24.9% on PA radiographs and 33.9% on CBCT images. CONCLUSION: The current study shows an inter-examiner agreement of moderate to perfect kappa statistic does not align with the most commonly selected criteria among examiners, showing poor examiner agreement among lesions. / 2024-06-21T00:00:00Z

The demand for high data rates communication and scarcity of spectrum in existing microwave bands has been the key aspect in 5G. To fulfill these demands, the millimeter wave (mmWave) with large bandwidths has been proposed to enhance the efficiency and the stability of the 5G network. In mmWave communication, the concentration of the transmission signal from the antenna is conducted by beamforming and beam tracking. However, state-of-art methods in beam tracking lead to high resource consumption. To address this problem, we develop 2 machine-learning-based solutions for overhead reduction. In this paper, a scenario configuration simulator is proposed as the data collection approach. Several LSTM based time series prediction models are trained for experiments. Since the overhead is reduced by decreasing the number of sweeping beams in solutions, multiple data imputation methods are proposed to improve the performance of the solution. These methods are based on Multiple Imputation by Chained Equations (MICE) and generative adversarial networks. Both qualitative and quantitative experimental results on several types of datasets demonstrate the efficacy of our solution. / Efterfrågan på hög datahastighetskommunikation och brist på spektrum i befintliga mikrovågsband har varit nyckelaspekten i 5G. För att uppfylla dessa krav har millimetervåg (mmWave) med stora bandbredder föreslagits för att förbättra effektiviteten och stabiliteten i 5G-nätverket. I mmWavekommunikation utförs koncentrationen av överföringssignalen från antennen genom strålformning och strålspårning. Toppmoderna metoder inom strålspårning leder dock till hög resursförbrukning. För att lösa detta problem utvecklar vi två maskininlärningsbaserade lösningar för reduktion av omkostnader. I det här dokumentet föreslås en scenariokonfigurationssimulator som datainsamlingsmetod. Flera LSTM-baserade modeller för förutsägelse av tidsserier tränas för experiment. Eftersom omkostnaderna reduceras genom att minska svepstrålarna i lösningar föreslås flera datainputeringsmetoder för att förbättra lösningens prestanda. Dessa metoder är baserade på Multipel Imputation by Chained Equations (MICE) och generativa kontroversiella nätverk. Både kvalitativa och kvantitativa experimentella resultat på flera typer av datamängder visar effektiviteten i vår lösning.

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京都大学 / 新制・課程博士 / 博士(工学) / 甲第24605号 / 工博第5111号 / 新制||工||1978(附属図書館) / 京都大学大学院工学研究科機械理工学専攻 / (主査)教授 平山 朋子, 教授 松原 厚, 教授 小森 雅晴 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

<p>Optical beam steering is of significant importance for various emerging applications such as light detection and ranging (LiDAR), free space optical communication, and holographic display. However, the development of schemes for dynamic spatio-temporal beam steering has been limited in the past. A previous study achieved dynamic and continuous angular beam steering of isolated ultrashort pulses from a mode-locked laser by using a passive metasurface emulating a diffraction grating followed by a lens. In this thesis, we experimentally demonstrate dynamic spatio-temporal steering of high repetition rate pulse trains using a spatial array of frequency combs with a uniform gradient in their carrier-envelope offsets. To accomplish this, we leverage the capabilities of a virtually imaged phased array (VIPA), which is a side-entrance Fabry-Perot etalon, and employ successive spatial Fourier transforms facilitated by a 4f optical lens system. Our experimental results successfully demonstrate the periodic scanning of ultrashort pulse trains generated from an electro-optic comb at a repetition rate of ~10 GHz. The scanning occurs in discrete steps of ~115 μm and ~20 ps in the spatial and temporal domains, respectively.</p>

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We investigate the spatial evolution of an intense laser pulse as it generates high-order harmonics in a long gas cell, filled with 80 torr of helium. A thin foil separates the gas-filled region of the cell from a subsequent evacuated region. The exit plane of the gas cell can be scanned along the laser axis so that the evolution of the laser throughout the focus can be observed (full scanning range of 9 cm). We constructed an apparatus that images the laser radial energy profile as it exits the cell. The high harmonics, odd orders ranging from 45 to 91, are observed at the same time that the laser spot is characterized. Re-absorption of the harmonics within the gas cell restricts the region of harmonic emission to the final centimeter (or less) of the cell. We present the first direct evidence (to our knowledge) of laser filamentation under conditions ideal for high-order harmonic generation. The 30 fs, 4 mJ, laser pulses were observed to undergo double focusing within the gas cell, with about 4 cm separating the two foci. The region with best harmonic emission occurs midway between the two foci. The radial profile of the laser focus, 150-200 microns in diameter, evolves from a Gaussian-like profile to a more square-top profile as it propagates over several centimeters. The filamentation phenomenon as well as the brightness of the harmonics improves when an aperture is partially closed on the laser beam before reaching the focusing mirror. A spectral sampling of the imaged laser focus revealed a 4 nm blue-shift associated with the generation of plasma in the gas cell. The blue-shifting occurs primarily in the center of the laser beam and less at the wider radii. The initial laser pulse had a spectrum centered at 800 nm with a 35 nm bandwidth. The energy associated with each of the observed 26 harmonic beams was found to be approximately 1 nJ, yielding a conversion efficiency of approximately 2e−7.

Vanadium dioxide (VO_2) is a material of particular interest due to its exhibited metal to insulator phase transition at 68°C that is accompanied by an abrupt and significant change in its electronic and optical properties. Since this material can exhibit a reversible drop in resistivity of up to five orders of magnitude and a reversible drop in infrared optical transmission of up to 80%, this material holds promise in several technological applications. Solid phase crystallization of VO_2 thin films was obtained by a post-deposition annealing process of a VO_{x,x approx 2} amorphous film sputtered on an amorphous silicon dioxide (SiO_2) layer. Scanning electron microscopy (SEM) and electron-backscattered diffraction (EBSD) were utilized to study the morphology of the solid phase crystallization that resulted from this post-deposition annealing process. The annealing parameters ranged in temperature from 300°C up to 1000°C and in time from 5 minutes up to 12 hours. Depending on the annealing parameters, EBSD showed that this process yielded polycrystalline vanadium dioxide thin films, semi-continuous thin films, and films of isolated single-crystal particles. In addition to these films on SiO_2, other VO_2 thin films were deposited onto a-, c-, and r-cuts of sapphire and on TiO_2(001) heated single-crystal substrates by pulsed-laser deposition (PLD). The temperature of the substrates was kept at ~500°C during deposition. EBSD maps and orientation imaging microscopy were used to study the epitaxy and orientation of the VO_2 grains deposited on the single crystal substrates, as well as on the amorphous SiO_2 layer. The EBSD/OIM results showed that: 1) For all the sapphire substrates analyzed, there is a predominant family of crystallographic relationships wherein the rutile VO_2{001} planes tend to lie parallel to the sapphire's {10-10} and the rutile VO_2{100} planes lie parallel to the sapphire's {1-210} and {0001}. Furthermore, while this family of relationships accounts for the majority of the VO_2 grains observed, due to the sapphire substrate's geometry there were variations within these rules that changed the orientation of VO_2 grains with respect to the substrate's normal direction. 2) For the TiO_2, a substrate with a lower lattice mismatch, we observe the expected relationship where the rutile VO_2 [100], [110], and [001] crystal directions lie parallel to the TiO_2 substrate's [100], [110], and [001] crystal directions respectively. 3) For the amorphous SiO_2 layer, all VO_2 crystals that were measurable (those that grew to the thickness of the deposited film) had a preferred orientation with the the rutile VO_2[001] crystal direction tending to lie parallel to the plane of the specimen. The use of transmission electron microscopy (TEM) is presented as a tool for further characterization studies of this material and its applications. In this work TEM diffraction patterns taken from cross-sections of particles of the a- and r-cut sapphire substrates not only solidified the predominant family mentioned, but also helped lift the ambiguity present in the rutile VO_2{100} axes. Finally, a focused-ion beam technique for preparation of cross-sectional TEM samples of metallic thin films deposited on polymer substrates is demonstrated.