Bacterial community analysis in upflow multilayer anaerobic reactor (UMAR) treating high-solids organic wastes

A novel anaerobic digestion configuration, the upflow multi-layer anaerobic reactor (UMAR), was developed to treat high-solids organic wastes. The UMAR was hypothesized to form multi-layer along depth due to the upflow plug flow; use of a recirculation system and a rotating distributor and baffles aimed to assist treating high-solids influent. The chemical oxygen demand (COD) removal efficiency and methane (CH4) production rate were 89% and 2.10 L CH4/L/day, respectively, at the peak influent COD concentration (110.4 g/L) and organic loading rate (7.5 g COD/L/day). The 454 pyrosequencing results clearly indicated heterogeneous distribution of bacterial communities at different vertical locations (upper, middle, and bottom) of the UMAR. Firmicutes was the dominant (>70%) phylum at the middle and bottom parts, while Deltaproteobacteria and Chloroflexi were only found in the upper part. Potential functions of the bacteria were discussed to speculate on their roles in the anaerobic performance of the UMAR system

Mobilizing Consensus on Facebook: Networked Framing of the U.S. Gun-Control Movement on Facebook

This study draws on networked framing and intermedia network agenda-setting theories to examine how different informational actors have framed the March for Our Lives gun control movement in 2018. This study uses the Social Science One Facebook URLs share dataset to compare network-agenda setting of different media types including offline news media, partisan sites, nonpartisan sites, advocacy/activism organizations, and social media/aggregate services. Results suggest that news media’s framing was the richest and most dynamic, suggesting their important roles in setting the gun issue as a salient public agenda. Meanwhile, emerging media expanded the scope of framing by covering race, gender, and equity issues into gun politics. The movement/activist organizational actors showed the least similarity to other media types, inviting further questions on the role of movement/activist actors in shaping public attention and agendas in the process

Three essays on trade liberalization and Korean agriculture

Since the Uruguay Round Agreement on Agriculture (URAA) in 1994, global competition in Korean agricultural markets has significantly increased. The objective of this dissertation is to identify the effects of trade liberalization on productivity and pricing in the Korean rice market (Essay 1 and 2) and on the entire agricultural sector (Essay 3). Rice is the major agricultural commodity in Korean agriculture with Rice Processing Complexes (RPC), i.e. agricultural cooperatives, playing a major role in the rice processing industry. Essays 1 and 2 examine RPCs adjustment to the increasingly competitive market environment. The first essay draws on the emerging heterogeneous-firms trade model to test the hypothesis that trade liberalization forces least productivity firms to exit (extensive margin) and encourages reallocation of resources and market share to high productivity firms (intensive margin) within an industry. The above churning results in an increase in the average productivity of the industry. Results from using plant-level RPC data from 2002-2008 to test the above hypothesis show that international competition via increases in rice import (Minimum Market Access) has the largest effect on RPCs' productivity. In particular, greater competition shifts the left tail of the productivity distribution to the right, increasing the median productivity of the Korean rice processing industry. Thus, the above findings suggest that RPCs, often considered to be quasi-public firms shielded from competition, face significant adjustment following trade liberalization. Economic theory suggests that a key input, i.e. raw product that farmer-members deliver, is treated as given in marketing cooperatives’ optimization, unlike in the case of profit maximizing firms. Thus, only if cooperatives minimize the cost of conventional inputs (labor and capital) cost and additionally, set the price of the raw product optimally, their production is efficient. Essay 2 examines RPCs' pricing efficiency, based on the above theory, by incorporating farmers' supply function of raw product (rice) into hypothesized RPCs' optimization framework. Results show that only large RPCs' pricing and thus, production is efficient. For small and medium RPCs, processing size, i.e. realizing economies of scale, is important for their efficiency. The latter finding suggests merger of neighboring small and medium RPCs to both expand supply of raw rice and lower processing costs. In fact, results show that post-merger RPCs have attained pricing efficiency similar to large RPCs. Since 2002, about 20 percent of Korean RPCs have merged adjusting to the competitive market and improving pricing efficiency and overall productivity. In the third essay, the effects of agricultural openness on aggregate agricultural productivity and farmers' welfare in Korea are examined. Results indicate that the openness significantly improves agricultural productivity, with a marked increase following URAA. However, in real terms, farm products' price and net farm business income have declined after trade liberalization. The findings show that agricultural trade liberalization has greatly benefitted Korean consumers, but the net impact on farmers' welfare from productivity growth, real price decline and transfer payments is less clear. The three essays show that Korean agriculture has been adjusting to the increasingly competitive environment in primary and processing sectors, contributing to overall gains for the Korean economy. Encouraging resource reallocation towards more competitive segments of Korean agriculture along with targeted transfer payments to revitalize losers from trade are needed to continue to realize and share gains from trade.Keywords: Trade Liberalization, Korean Agriculture, Agricultural Cooperative, Productivity Growth, Resource Reallocation, Pricing Efficienc

Comparison of supercritical and near-critical carbon dioxide extraction of carotenoid enriched wheat bran oil

Supercritical and near-critical carbon dioxide (CO2) extraction were carried out to extract oil from wheat bran. The extraction temperatures for supercritical and near-critical CO2 were 35 - 45°C and 25 - 30°C, respectively. The applied pressure was ranging from 10 to 30 MPa for both supercritical and near-critical CO2 extraction. The extraction was performed in a semi batch process with a CO2 flow rate of 26.81 g/min for 1.5 h. The oil obtained from wheat bran at different extraction conditions was quantitatively measured to  investigate the solubility of oil at supercritical and near-critical CO2. The highest solubility was found at near-critical condition. The fatty acid compositions of wheat bran oil were measured by gas chromatography (GC). Linoleic, palmitic, oleic and γ-linolenic acid were the major fatty acids of wheat bran oil. Total carotenoid was measured spectrophotometerically. Highest yield of total carotenoid was found at 45°C and 30 MPa.Key words: Supercritical and near-critical carbon dioxide, wheat bran oil, total carotenoid

Knowledge Sharing Network in a Community of Illicit Practice: A Cybermarket Subreddit Case

Often neglected in the literature about communities of practice is the fact that online knowledge-sharing communities thrive among illicit collectives whose activities are stigmatized or outlawed. This paper focuses on a knowledge-sharing community of users who engage in illegal practices by examining the ways in which the community’s network structure changes when a high-stakes, uncertain event—the July 2017 shutdown of the dark web market Alphabay—occurs. This study compares the discussion network structures in the subreddit r/AlphaBay during pre-shutdown days (the “routine” period) and shutdown days (the “market defect” period) and offers a content analysis of the knowledge and resources shared by users during these periods. Several differences were observed: (a) the network structure changed such that the network size grew while becoming more centralized; (b) new crisis-specific players emerged; (c) types of knowledge shared during the market defect period was qualitatively different from the routine period