224 research outputs found

    Specimen Test of Large-Heat-Input Fusion Welding Method for Use of SM570TMCP

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    In this research, the large-heat-input welding conditions optimized to use the rear plate and the high-performance steel of SM570TMCP, a new kind of steel suitable for the requirements of prospective customers, are proposed. The goal of this research is to contribute to securing the welding fabrication optimized to use the high-strength steel and rear steel plates in the field of construction industry in the future. This research is judged to contribute to securing the welding fabrication optimized to use the high-strength steel and rear steel plates in the field of construction industry in the future

    MRI Visualization of Whole Brain Macro- and Microvascular Remodeling in a Rat Model of Ischemic Stroke: A Pilot Study

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    Using superparamagnetic iron oxide nanoparticles (SPION) as a single contrast agent, we investigated dual contrast cerebrovascular magnetic resonance imaging (MRI) for simultaneously monitoring macro- and microvasculature and their association with ischemic edema status (via apparent diffusion coefficient [ADC]) in transient middle cerebral artery occlusion (tMCAO) rat models. High-resolution T1-contrast based ultra-short echo time MR angiography (UTE-MRA) visualized size remodeling of pial arteries and veins whose mutual association with cortical ischemic edema status is rarely reported. ??R2?????R2*-MRI-derived vessel size index (VSI) and density indices (Q and MVD) mapped morphological changes of microvessels occurring in subcortical ischemic edema lesions. In cortical ischemic edema lesions, significantly dilated pial veins (p???=???0.0051) and thinned pial arteries (p???=???0.0096) of ipsilateral brains compared to those of contralateral brains were observed from UTE-MRAs. In subcortical regions, ischemic edema lesions had a significantly decreased Q and MVD values (p???<???0.001), as well as increased VSI values (p???<???0.001) than normal subcortical tissues in contralateral brains. This pilot study suggests that MR-based morphological vessel changes, including but not limited to venous blood vessels, are directly related to corresponding tissue edema status in ischemic stroke rat models

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    Department of Biomedical EngineeringMagnetic susceptibility contrast MRI using local magnetic field gradients or inhomogeneities is expected to provide low-resolution quantification of tissue microarchitecture, as magnetic resonance (MR) transverse relaxation times (T2 and T2*) are influenced by field inhomogeneity arising from susceptibility mismatch of tissues. By aid of ultra-high field MRI scanner, MR transverse relaxation times is promising to further increase their sensitivity to detecting subtle structural changes in tissue microstructures. However, one of the main technical difficulty of ultra-high field MRI is unwanted variations of signal and contrast, or even worse, nullify the MR signal due to increased macroscopic static magnetic field inhomogeneities which are prone to misinterpretation and loss of structural information. This study focuses on improving the sensitivity and the robustness of ultra-high field MRI (particularly for 7 T) from unwanted signal variations due to magnetic field inhomogeneities and shortened MR transverse relaxation times. MR transverse relaxation times were investigated for the low-resolution assessment of tissue microstructures, such as trabecular bone microstructure and cerebral microvasculature. As a result, T2 relaxation time without having an effect of macroscopic field inhomogeneities may be suitable for the assessment of trabecular structural indices and robust with degrading spatial resolution with reduced scan time at 7 T. For the assessment of cerebral microvasculature, the diffusion-time-dependent stimulated-echo-based MR relaxation-rates was demonstrated as robust measures for assessing small (diameter < 5 ??m) cerebral microvasculature, where macroscopic field inhomogeneities from bone (air)-tissue interfaces and influences of large vessels in cortical region are significant. Finally, the quantification of MR longitudinal relaxation time (T1) was optimized by variable repetition-delay turbo-spin echo method with sparse encoding technique.clos

    Income Inequality, Social Mobility, and Electoral Participation in the U.S. Counties: Revisiting the Inequality-Participation Nexus

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    Previous research has provided contested hypotheses about the impact of income inequality on electoral participation. This study reexamines the debate between conflict and relative power theories by focusing on a largely ignored factor: social mobility. We argue that social mobility conditions the inequality-participation nexus by alleviating the frustration, class conflict, and efficacy gaps between the rich and the poor that the prevailing theories assume income inequality to create. By utilizing the Cooperative Congressional Election Survey, we test this argument focusing on US counties. Our analysis confirms that the effects of income inequality on citizensā€™ likelihood of voting vary depending on mobility, suggesting that social mobility provides a crucial context in which income inequality can play out in substantially different ways. This article implies that more scholarly endeavors should be made to clarify the multifaceted structure of inequality for improving our understanding of the relationship between economic and political inequality

    Economic Inequality and Political Participation in East Asian Democracies: The Role of Perceived Income Inequality and Intergenerational Mobility

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    This study examines how perceptions of economic inequality affect political participation focusing on East Asian democracies. It develops nuanced predictions on how perceptions of income inequality and social mobility and their interplay affect individualsā€™ engagement in various types of political activities in six East Asian democracies. Using the fourth wave of the Asian Barometer Survey, we examine novel arguments built upon the existing inequality-participation nexus. Our analysis suggests that inequality is a multifaceted concept, and the mechanisms of the inequality-participation nexus could vary depending on the regional, socioeconomic, and political context
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