THREE ESSAYS ON ORGANIC AGRICULTURE

This dissertation contains three pieces of empirical research in organic agricultural economics. The first essay examines the factors that influence farmers to choose direct marketing strategy and estimate the impacts of direct marketing on farm performance, with considering farms’ locational environment and spatial interaction between farmers’ choice of marketing strategy. Results from the Endogenous treatment model show that variables of geographic location and spatial interaction have significant influences on marketing strategy choice, and some of geographic variables are associated with farm sales. Also, it is found that there exists direct marketing penalty on the average, while for the smaller farms, the amount of the difference in expected sales is not significant across the marketing strategies, implying that direct marketing may be a viable strategy for some smaller farms. The second research investigates a number of scenarios that represent pest or disease outbreak due to climate change. This research constructed dynamic model of the U.S. apple industry that is separated into organic and conventional industries to better measure the impacts of pest or disease outbreaks on producers and consumers. Findings in this study suggest that there would be heterogenous impacts of the outbreaks between organic and conventional industries and by type of shock since production systems and growers and consumers’ responses to shock could differ widely across industry.The third essay investigates the impacts of price premium on the supply of organic crops. This study estimates an econometric model of land adjustment and yields to determine how the elasticity of supply depends on the market-level organic premium versus farm-level prices. This essay first estimates the supply responses at the aggregate-level and then analyze a rich farm-level dataset. The aggregate-level results show that acreage, production, and yield responses to price premiums and/or own prices are positive as expected, while the long-run production and yield elasticities are inelastic relative to acreage responses. The farm-level results suggest that farm’s yield responds to the average market prices more than the prices they received, and that organic apple producers may depend on the organic premiums rather than organic prices when they invest in organic apple acres

Frame flow between government and the news media and its effects on the public: Framing of North Korea

This is the author's accepted manuscript, made available with the permission of the publisher. Copyright 2009 Oxford University PressPublic opinion is likely to be susceptible to the way a government and the news media frame foreign countries, because unlike domestic issues, foreign news is typically beyond a person's direct experience. How does the American public respond to foreign news when its government and the news media promote competing frames and change their prominence according to the relations between the U.S. and that foreign country? The present study shows this frame building and frame effects by using a public opinion poll and content analysis of U.S. policy statements and media coverage. North Korea was chosen because its visibility to the American public has increased since President George W. Bush designated it as one of the countries in the “axis of evil”. The results show that during a four-month period, the U.S. government and the newspaper produced three competing frames, and that the magnitude of the frames shifted as U.S.–North Korean relationships shifted. These shifts in turn made the American public choose economic sanctions over military solutions toward the country

Meaning of Epistemological Belief Through Online Communication: Exploratory Study

AbstractLearners’ perceptions of instructional practice may vary depending on their own different epistemological perspectives (Hofer, 2004). In other words, learners’ beliefs about knowing may influence their attitude towards learning-related activities. Based on this assumption, the study focuses on how a learner's epistemological beliefs shape their experiences in relation to learning. The hypothesis is applied for online communication platforms like a Social Networking Service (SNS) which is a non-traditional learning environment where learners do not seek any explicit goals related to learning. To investigate this hypothesis, the study analyzed the survey results from 169 Korean adult bloggers and SNS users. The initial results show that the participants’ epistemological beliefs affect their definition of learning and their perception of a particular experience as meaningful or learning-related. Moreover, those who hold a broader epistemological belief tend to have a more comprehensive definition of learning and use online communication tools in a more meaningful way. Moreover such platforms for social communication tend to support learners to change their view of learning. In conclusion, this study may advance our understanding of epistemological belief, its role in learning, and the mediating role of social communicatio

Ant Colony Optimized Routing Strategy for Electric Vehicles

Electric vehicles (EVs) have recently attracted increasing research interest, on account of environmental issues and diminishing fuel reserves. EVs are environmentally friendly but have a short driving range. EVs must utilize energy efficiently, because they travel with limited energy. Conventional vehicle routing methods are not suitable for EVs, as they do not take energy consumption into account. This study introduces an energy efficient routing method using ant colony optimization (ER-ACO) to maximize the energy efficiency. We simulated ER-ACO and compared it with other ACO techniques, including the conventional routing method and other approaches for EVs. As a result, the proposed model improved the energy efficiency in terms of both the average distance per kW and average energy consumption. Document type: Articl

A degree reduction method for an efficient QUBO formulation for the graph coloring problem

We introduce a new degree reduction method for homogeneous symmetric polynomials on binary variables that generalizes the conventional degree reduction methods on monomials introduced by Freedman and Ishikawa. We also design an degree reduction algorithm for general polynomials on binary variables, simulated on the graph coloring problem for random graphs, and compared the results with the conventional methods. The simulated results show that our new method produces reduced quadratic polynomials that contains less variables than the reduced quadratic polynomials produced by the conventional methods

Radiomics signature on 3T dynamic contrast-enhanced magnetic resonance imaging for estrogen receptor-positive invasive breast cancers: Preliminary results for correlation with Oncotype DX recurrence scores

To evaluate the ability of a radiomics signature based on 3T dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) to distinguish between low and non-low Oncotype DX (OD) risk groups in estrogen receptor (ER)-positive invasive breast cancers.Between May 2011 and March 2016, 67 women with ER-positive invasive breast cancer who performed preoperative 3T MRI and OD assay were included. We divided the patients into low (OD recurrence score [RS] <18) and non-low risk (RS ≥18) groups. Extracted radiomics features included 8 morphological, 76 histogram-based, and 72 higher-order texture features. A radiomics signature (Rad-score) was generated using the least absolute shrinkage and selection operator (LASSO). Univariate and multivariate logistic regression analyses were performed to investigate the association between clinicopathologic factors, MRI findings, and the Rad-score with OD risk groups, and the areas under the receiver operating characteristic curves (AUC) were used to assess classification performance of the Rad-score.The Rad-score was constructed for each tumor by extracting 10 (6.3%) from 158 radiomics features. A higher Rad-score (odds ratio [OR], 65.209; P <.001), Ki-67 expression (OR, 17.462; P = .007), and high p53 (OR = 8.449; P = .077) were associated with non-low OD risk. The Rad-score classified low and non-low OD risk with an AUC of 0.759.The Rad-score showed the potential for discrimination between low and non-low OD risk groups in patients with ER-positive invasive breast cancers. Copyright © 2019 the Author(s)

The mid-infrared view of red sequence galaxies in Abell 2218 with <i>AKARI</i>

We present the AKARI Infrared Camera (IRC) imaging observation of early-type galaxies (ETGs) in A2218 at z ~ 0.175. Mid-infrared (MIR) emission from ETGs traces circumstellar dust emission from asymptotic giant branch (AGB) stars or/and residual star formation. Including the unique imaging capability at 11 and 15 μm, our AKARI data provide an effective way to investigate MIR properties of ETGs in the cluster environment. Among our flux-limited sample of 22 red sequence ETGs with precise dynamical and line strength measurements (less than 18 mag at 3 μm), we find that at least 41% have MIR-excess emission. The N3 – S11 versus N3 (3 and 11 μm) color-magnitude relation shows the expected blue sequence, but the MIR-excess galaxies add a red wing to the relation especially at the fainter end. A spectral energy distribution analysis reveals that the dust emission from AGB stars is the most likely cause of the MIR excess, with a low level of star formation being the next possible explanation. The MIR-excess galaxies show a wide spread of N3 – S11 colors, implying a significant spread (2-11 Gyr) in the estimated mean ages of stellar populations. We study the environmental dependence of MIR-excess ETGs over an area out to a half virial radius (~1 Mpc). We find that the MIR-excess ETGs are preferentially located in the outer region. From this evidence, we suggest that the fainter, MIR-excess ETGs have just joined the red sequence, possibly due to the infall and subsequent morphological/spectral transformation induced by the cluster environment

Investigation of Antimony in Natural Water and Leaching from Polyethylene Terephthalate (PET) Bottled Water

Abstract -Antimony (Sb) is one of the trace hazardous compounds in drinking water. Recent studies demonstrated that polyethylene terephthalate (PET) bottles can release antimony into water. It is also found on natural environment such as groundwater and crustal rocks. The natural content of Sb in northern Gyeonggi province in South Korea was very low range from 0.02~0.32 μg/L. The source water and tap water for 15 water supply plants from river or reservoir showed 0.13 μg/L on average. The groundwater concentration from 50 mineral springs indicated significantly low at 0.02 μg/L. The concentration of antimony was investigated in 47 bottled water brands on market. The average of Sb in bottled water brands was 0.57 μg/L. The detection rate was 100% in these products. Otherwise, raw water for bottled water contained 0.32 μg/L of antimony and detection rate was 90.7%. As a results of leaching experiment, antimony content in PET bottled water was increased from 1.04 to 9.84 μg/L under 60℃ after 12weeks. In case, the bottled water was stored in over 35℃, antimony leached into water. UV-ray irradiation to bottled water not induced increasing antimony release into water following 14days

Clinical characteristics of myelin oligodendrocyte glycoprotein antibody-associated disease according to their epitopes

BackgroundThe detection of myelin oligodendrocyte glycoprotein autoantibodies (MOG-Ab) is essential for the diagnosis of MOG-Ab-associated disease (MOGAD). The clinical implications of different epitopes recognized by MOG-Ab are largely unknown. In this study, we established an in-house cell-based immunoassay for detecting MOG-Ab epitopes and examined the clinical characteristics of patients with MOG-Ab according to their epitopes.MethodsWe conducted a retrospective review of patients with MOG-Ab-associated disease (MOGAD) in our single center registry, and collected serum samples from enrolled patients. Human MOG variants were generated to detect epitopes recognized by MOG-Ab. The differences in clinical characteristics according to the presence of reactivity to MOG Proline42 (P42) were evaluated.ResultsFifty five patients with MOGAD were enrolled. Optic neuritis was the most common presenting syndrome. The P42 position of MOG was a major epitope of MOG-Ab. The patients with a monophasic clinical course and childhood-onset patients were only observed in the group that showed reactivity to the P42 epitope.ConclusionWe developed an in-house cell-based immunoassay to analyze the epitopes of MOG-Ab. The P42 position of MOG is the primary target of MOG-Ab in Korean patients with MOGAD. Further studies are needed to determine the predictive value of MOG-Ab and its epitopes