Limited Angle Ultrasound Tomography of the Compressed Breast

X-ray mammography is widely accepted as the clinical standard for breast cancer screening and diagnosis. However, reflection mode ultrasound has been known to outperform x-ray in screening performance in dense breasts. With newer modes of ultrasound, acoustic properties of breast tissue, such as the speed of sound and attenuation coefficient distributions, can be extracted from captured ultrasound signals and used to characterize breast tissue types and contribute to detection and diagnosis of malignancy. The same is possibly true for optical absorption via photoacoustic imaging. Recently, we have developed a dual-sided ultrasound scanner that can be integrated with existing x-ray mammographic systems and acquire images in the mammographic view and compression. Transmission imaging for speed of sound and attenuation coefficient in this geometry is termed limited angle tomography, as the beams at frequencies yielding high resolution cannot transit the long axis of the compressed breast. This approach, ideally, should facilitate the co-registration and comparisons between images from three modalities discussed here (x-ray, ultrasound and photoacoustic) and increase diagnostic detection confidence. However, potential limitations inherent in limited angle tomography have received minimal exploration up to this study, and existing imaging techniques developed for this approach are based on overly optimistic assumptions that hinder achievement of the desired image quality. This investigation of these problems should contribute valuable information to the validation and translation of the mammographically-configured, dual-sided ultrasound, or ultrasound and photoacoustic, scanner to the clinic. This dissertation first aims to extensively identify possible sources of error resulting from imaging in the limited angle tomography approach. Simulation findings mapping parametric conditions reveal that image artifacts arising in reflection mode (B-mode) can be modulated or mitigated by ultrasound gels with adequate acoustic properties. In addition, sound speed imaging was performed determining the level of significance for several key sources of error. Results suggest that imaging in transmission mode is the most sensitive to transducer misplacement in the signal propagation direction. This misplacement, however, could be minimized easily by routinely calibrating transducer positions. Next, this dissertation aims to advance speed of sound, attenuation, and photoacoustic image reconstruction algorithms for the limited angle tomography approach. This was done by utilizing both structural information of the imaged objects/tissues by means of the corresponding reflection mode images taken from the same imaging location, and a full acoustic modeling framework to account for complex acoustic interactions within the field of view. We have shown through simulations that both a priori information from reflection mode images and full acoustic modeling contribute to a noticeable improvement in the reconstructed images. Work done throughout the course of this dissertation should provide a foundation and insight necessary for improvements upon the existing dual-sided ultrasound scanner towards breast imaging in the clinic.PHDBiomedical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/143944/1/rungroj_1.pd

Simulating dioxane transport in a heterogeneous glacial aquifer system (Washtenaw County, Michigan) using publicly available models and data

The primary challenge in groundwater and contaminant transport modeling is obtaining the data needed for constructing, calibrating and testing the models. Large amounts of data are necessary for describing the hydrostratigraphy in areas with complex geology. Increasingly states are making spatial data available that can be used for input to groundwater flow models. The appropriateness of this data for large-scale flow systems has not been tested. This study focuses on modeling a plume of 1,4-dioxane in a heterogeneous aquifer system in Scio Township, Washtenaw County, Michigan. The analysis consisted of: (1) characterization of hydrogeology of the area and construction of a conceptual model based on publicly available spatial data, (2) development and calibration of a regional flow model for the site, (3) conversion of the regional model to a more highly resolved local model, (4) simulation of the dioxane plume, and (5) evaluation of the model\u27s ability to simulate field data and estimation of the possible dioxane sources and subsequent migration until maximum concentrations are at or below the Michigan Department of Environmental Quality\u27s residential cleanup standard for groundwater (85 ppb). MODFLOW-2000 and MT3D programs were utilized to simulate the groundwater flow and the development and movement of the 1, 4-dioxane plume, respectively. MODFLOW simulates transient groundwater flow in a quasi-3-dimensional sense, subject to a variety of boundary conditions that can simulate recharge, pumping, and surface-/groundwater interactions. MT3D simulates solute advection with groundwater flow (using the flow solution from MODFLOW), dispersion, source/sink mixing, and chemical reaction of contaminants. This modeling approach was successful at simulating the groundwater flows by calibrating recharge and hydraulic conductivities. The plume transport was adequately simulated using literature dispersivity and sorption coefficients, although the plume geometries were not well constrained

Dry Methane Reforming Performance of Ni-based Catalyst Coated onto Stainless Steel Substrate

AbstractIn this work, the Ni-based catalysts (10wt.%Ni/Al2O3-MgO and 10wt.%Ni/MgO) were synthesized by sol-gel method. Each catalyst was prepared as catalyst pellets and catalyst-coated plate, stainless steel plate coated with catalyst. The catalyst-coated plates were fabricated using spray coating. The dry methane reforming (DMR) performances of catalyst-coated plate were investigated and compared with DMR performances of catalyst pellets. As the mass transfer was improved, the methane consumption rate per gram of catalyst coated onto metal plate was ten times greater than those of catalyst pellets approximately. The carbon deposition was also significantly prevented when the catalyst was constructed as a thin-film layer on the plate under our developing condition. Therefore, this catalyst-coated plate can be further developed for multichannel reactor

Electrical Resistivity Imaging for Unknown Bridge Foundation Depth Determination

Unknown bridge foundations pose a significant safety risk due to stream scour and erosion. Records from older structures may be non-existent, incomplete, or incorrect. Nondestructive and inexpensive geophysical methods have been identified as suitable to investigate unknown bridge foundations. The objective of the present study is to apply advanced 2D electrical resistivity imaging (ERI) in order to identify depth of unknown bridge foundations. A survey procedure is carried out in mixed terrain water and land environments with rough topography. A conventional resistivity survey procedure is used with the electrodes installed on the stream banks. However, some electrodes must be adapted for underwater use. Tests were conducted in one laboratory experimentation and at five field experimentations located at three roadway bridges, a geotechnical test site, and a railway bridge. The first experimentation was at the bridges with the smallest foundations, later working up in size to larger drilled shafts and spread footings. Both known to unknown foundations were investigated. The geotechnical test site is used as an experimental site for 2D and 3D ERI. The data acquisition is carried out along 2D profile with a linear array in the dipole-dipole configuration. The data collections have been carried out using electrodes deployed directly across smaller foundations. Electrodes are deployed in proximity to larger foundations to image them from the side. The 2D ERI can detect the presence of a bridge foundation but is unable to resolve its precise shape and depth. Increasing the spatial extent of the foundation permits better image of its shape and depth. Using electrode < 1 m to detect a slender foundation < 1 m in diameter is not feasible. The 2D ERI method that has been widely used for land surface surveys presently can be adapted effectively in water-covered environments. The method is the most appropriate geophysical method for determination of unknown bridge foundations. Fully 3D ERI method at bridge sites is labor intensive, time consuming, and does not add enough value over 2D ERI to make it worthwhile

Average systolic blood pressure and clinical outcomes in patients with atrial fibrillation:Prospective data from COOL-AF registry

PurposeHypertension is associated with incident atrial fibrillation (AF) and AF-related complications. We investigated the associations between average systolic blood pressure (SBP) and outcomes in a nationwide cohort of Asian patients with non-valvular atrial fibrillation (NVAF).Patients and methodsA multicenter nationwide registry of patients with NVAF in Thailand was conducted during 2014-2017. Clinical data, including blood pressure, were recorded at baseline and then every 6 months. Average SBP was calculated from the average of SBP from every visit. Cox regression models were used to calculate the rate of clinical outcomes of interest, ie ischemic stroke or transient ischemic attack (TIA), intracerebral hemorrhage (ICH), and all-cause death. Average SBP was categorized into three groups: ResultsA total of 3402 patients were included, and the mean age was 67.4±11.3 years. The mean (±SD) baseline and average SBPs were 128.5±18.5 and 128.0±13.4 mmHg, respectively. The mean follow-up duration was 25.7±10.6 months. The median rate of ischemic stroke/TIA, ICH, and all-cause death was 1.43 (1.17-1.74), 0.70 (0.52-0.92), and 3.77 (3.33-4.24) per 100 person-years, respectively. The rate of ischemic stroke/TIA and ICH was lowest in patients with average SBP ConclusionSustained control of SBP was significantly associated with a reduction in adverse clinical outcomes in patients with NVAF

Time in target range of systolic blood pressure and clinical outcomes in atrial fibrillation patients: results of the COOL-AF registry

We aimed to investigate the relationship between time in target range of systolic blood pressure (SBP-TTr) and clinical outcomes in patients with atrial fibrillation (AF). We analyzed the results from multicenter AF registry in Thailand. Blood pressure was recorded at baseline and at every 6 monthly follow-up visit. SBP-TTr were calculated using the Rosendaal method, based on a target SBP 120–140 mmHg. The outcomes were death, ischemic stroke/systemic embolism (SSE), major bleeding, and heart failure. A total of 3355 patients were studied (mean age 67.8 years; 41.9% female). Average follow-up time was 32.1 ± 8.3 months. SBP-TTr was classified into 3 groups according to the tertiles. The incidence rates of all-cause death, SSE, major bleeding, and heart failure were 3.90 (3.51–4.34), 1.52 (1.27–1.80), 2.2 (1.90–2.53), and 2.83 (2.49–3.21) per 100 person-years, respectively. Patients in the 3rd tertile of SBP-TTr had lower rates of death, major bleeding and heart failure with adjusted hazard ratios 0.62 (0.48–0.80), p &lt; 0.001, 0.64 (0.44–0.92), p = 0.016, and 0.61 (0.44–0.84), p = 0.003, respectively, compared to 1st SBP-TTr tertile. In conclusion, high SBP-TTr was associated with better clinical outcomes compared to other groups with lower SBP-TTr. This underscores the importance of good blood pressure control in AF patients.</p

フィルタープレスドライヤーによるスラリーの真空脱水乾燥

取得学位：博士(工学)，学位授与番号：博甲第854号，学位授与年月日：平成18年9月28

Compressive Strength and Treatment Efficiency of Nitrogen-Dioxide of Paving Block Made of Concrete Mixing with Titanium-Dioxide

AbstractThis research studied the treatment efficiency of Nitrogen-dioxide (NO2) in air using concrete paving blockcontaining Titanium-dioxide (TiO2) which were 5x5x5 cm3 cubic specimens. They were plastered with concrete mixedwith TiO2 in the percentage of 0, 5, 10, and 15 by weight for the top layer of the specimens at 1 cm. This research studied the effect of doges of TiO2 on compressive strength at the age of 3, 7, 14, and 28 days and the NO2 treatment in air. The 28-cured days of specimens treated NO2 for several cycles (48 hours / cycle). The results showed that the doges of TiO2 did not effect on the compressive strengths of concrete paving block which was higher than designed mixes. For NO2 treatment, the treatment efficiency of concrete paving block containing 15 wt.% of Titanium-dioxide had higher than thespecimens. The 1st cycle for treatment had the efficiency of 48% and decreased when retreated in next cycles. At the 7 th cycles, the efficiency of concrete paving block decreased to lower than 10%. After that the tested specimens werepolished in order to remove the surface of concrete paving block for 0.1 cm. and retested. The efficiency of retestedspecimens was similar to new specimens. The polished surface of concrete paving block was stimulated corrosion on pathway and road. In addition, concrete paving block containing Titanium-dioxide were soaked in diluted Sulfuric acid in order to stimulated contact with acid rain. The results showed that concrete paving block containing Titanium-dioxide soaked in diluted Sulfuric acid (pH = 5) had the strength development and NO2 treatment efficiency were lower than when compared with specimens which soaked in water about 10 to 20 percen