京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第19404号 / 医博第4055号 / 新制||医||1012(附属図書館) / 32429 / 京都大学大学院医学研究科医学専攻 / (主査)教授 野田 亮, 教授 瀬原 淳子, 教授 藤渕 航 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

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As online shopping continues to grow rapidly, research indicates its massive uptake can be the result of the integration of social media technologies within the e-commerce interface. This has been further exacerbated by the COVID-19 pandemic which has led to an acceleration in the use of e-commerce. However, despite the growing popularity of e-commerce, shopping online is characterized by high levels of uncertainty given the spatial and temporal separation between consumer and vendor. This presents a dire impact on a consumer’s decision-making process and can specifically impact a consumer’s decision confidence. Decision confidence is an important construct that has been shown to be central in influencing a consumer’s behaviour, specifically in regards to purchase-related activities. Few studies have shed light on the factors influencing a consumer’s decision confidence in the e-commerce context. Online shopping platforms fitted with social data markers are able to gauge and track the activities and attributes of online consumers, providing convenient heuristics on various measures such as the total number of recommendations for a product, or the degree of similarity between consumers. These markers may facilitate group identification through the development of herd behaviour. Herd behaviour arises in situations of uncertainty and motivates individuals to identify with a group (herd), and conform to its actions. Various aspects of a herd can influence group identification. This research focuses on two aspects of herd behaviour in e-commerce environments: homophily and herd size. Homophily is the degree to which individuals are similar, and in this study, we examine homophily from the perspective of an individual and the herd to which they may be exposed to. Herd size is the number of individuals in a group taking a specific action such as an online purchase decision. Drawing on the social identity approach and uncertainty identity theory, this investigation hones in on how homophily and herd size arise in the e-commerce context, and examines how group identification through homophily and herd size may reduce uncertainty and build decision confidence through the formation of trust, entitativity, sense of community and information helpfulness. A research model is developed along with a set of supported hypotheses. An online experiment utilizing a hypothetical e-commerce website was conducted with 400 participants. The results were analyzed using structural equation modeling and choice-based conjoint analysis. The results suggest that while homophily significantly impacts trust, sense of community, entitativity and information helpfulness, herd size does not. The results also suggest that whereas trust, sense of community and information helpfulness positively impact decision confidence, entitativity does not. It was also empirically demonstrated that participants preferred measures of homophily in the e-commerce interface more than measures of herd size. Furthermore, it was demonstrated that participants preferred measures indicating homophily in interests and demographics more than information on either alone, and that information on homophily in interests was more preferred than information on homophily in demographics. / Dissertation / Doctor of Philosophy (PhD) / Despite the rapid uptake in e-commerce, shopping online continues to be characterized by high levels of uncertainty given the spatial and temporal separation between consumer and vendor. This uncertainty negatively impacts a consumer’s decision confidence, which is a key driver in influencing consumer behaviour. Drawing on the social identity approach and uncertainty identity theory, this study investigates how elements of the e-commerce interface can facilitate group identification, a process which has been empirically demonstrated to reduce uncertainty and thereby increase decision confidence. Findings of this study suggest that measures of homophily embedded within an e-commerce platform can work through various mediators to facilitate group membership which can positively impact a consumer’s decision confidence. Theoretical and practical contributions of this study are discussed for researchers, academics, and practitioners wishing to explore those aspects of online shopping that an aid the decision-making process through group-related processes.

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This thesis uses CFPS's 2014 and 2016 data, from the perspective of differences in education levels and city size, using the two-way fixed-effect model and quantile regression to explore how the different educational workers' nominal monthly income gap changes with the expansion of the urban population. As for city size, on average, for every 1% increase in city size, the nominal monthly income of workers will increase by 0.4%. For every 1% increase in the size of the city, the nominal monthly wage of the college education group will increase by 0.9%, and the wage of the postgraduate workers will increase almost by 1.2%. The results show that only workers with a college and postgraduate education level can expand the monthly income gap with the lowest educational level group as the urban population grows. However, the nominal monthly income gap between the high-school educated group and junior high school and below educated workers is insignificantly affected by the city's expansion. JEL Classification J31, J23, J26, C51, I18 Keywords Education Level, City Size, Wage Title Wage Differentials by Education level and City Size: Evidence from Chinese cities Abstrakt Tato práce využívá data CFPS z let 2014 a 2016 z pohledu rozdílů v úrovních vzdělání a velikosti města pomocí dvoucestného modelu s fixním...

Composite sampling can be more cost effective than simple random sampling. This paper considers how to determine the optimum number of increments to use in composite sampling. Composite sampling terminology and theory are outlined and a model is developed which accounts for different sources of variation in compositing and data analysis. This model is used to define and understand the process of determining the optimum number of increments that should be used in forming a composite. The blending variance is shown to have a smaller range of possible values than previously reported when estimating the number of increments in a composite sample. Accounting for differing levels of the blending variance significantly affects the estimated number of increments.

One of the primary missions of the National Weather Service (NWS) is to use a network of more than 150 NEXRAD radar installations to monitor weather for threats to life and property. Large hail produced by severe thunderstorms is a major focus of this mission. An algorithm known as the Maximum Estimated Size of Hail (MESH) algorithm is in operational use to diagnose the presence and size of hail. This study aims to use dual-Doppler observations as well as the MESH algorithm to test the idea that storms that rotate produce larger hail. Previous studies have used polarimetric radar products to detect the presence of large hail and dual-Doppler methods have been used to study embryonic hail, but no research has tested the theory of hail and rotating storms with observational evidence. A set of 59 case studies was gathered; each included a hail report submitted by a trained weather spotter or NWS employee and complete radar observations through the depth of a storm from two radars. The radar observations were resampled to a three-dimensional Cartesian grid and a dual-Doppler analysis was run on each case study. A strong correlation (stronger even than the MESH algorithm) was found between measured vorticity and hail size, lending credence to the idea that rotating storms do indeed have a higher ceiling for hail production. However, no correlation was found between MESH error and rotation. Further research will be required to evaluate whether or not this relationship can be used to augment the MESH algorithm so as to improve its skill. / Master of Science

A system was designed to measure the effect of gap size on semi-span low Reynolds number wind tunnel experiments. The lift forces on NACA 1412, NACA 2412 and NACA 4412 half wings were measured using a strain gauge balance at chord Reynolds numbers of 100,000 and 200,000 and three different gap sizes including sealed gap. Pressure distributions on both airfoil top and bottom surfaces in the chord-wise direction near the gap were recorded for these airfoils. Also recorded was the span wise pressure distribution on both the airfoil surfaces at the quarter chord section. The results revealed that the presence of the gap, however small, affects the measurements. These effects were mainly observed in drop of lift and change in zero lift angle of attack and change in stall angle for the airfoil. The size of the gap is not linearly related to these changes, which also depend on the camber of the airfoil. These changes occur due to the flow through the gap from the lower surface to the upper surface of the model. The wing/end plate gap effect reduces along the span but is not fully restricted to the base of the model and the model behaves more like a full three-dimensional wing than a semi-span model. This study was made possible with the support of Department of Aerospace and Ocean Engineering, Virginia Polytechnic Institute and State University under the supervision of Dr. James Marchman / Master of Science

<p> Daily discharge data from five Southern Ontario river systems were statistically analysed to seek relationships between streamflow characteristics and basin size. From each river system, at least two stations were used to detennine such relationships. The physiographic characteristics of each river system were also examined and qualitatively related to the streamflow statistics. Comparisons between physiographic regions were expected to support the general nature of the results obtained for each river system.</p> <p> In Southern Ontario, drainage area is correlated with mean annual peak flows. When the flows were transformed into discharge per unit area no consistent effects of basin area on the streamflow characteristics were found. However, differences in streamflow per unit area between various sub-basins can be qualitatively explained by several physical characteristics of the drainage basins.</p> / Thesis / Bachelor of Science (BSc)