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Detection of Metagonimus sp. (Family Heterophyidae) Metacercariae from Freshwater Fishes in the Vicinity of Tong River, Kangwon Province, Korea (동강유역 담수어에 기생하는 흡충(Metagonimus sp.)의 피낭유출 감염 조사)

  • 전계식;김태선
    • Korean Journal of Environmental Biology
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    • v.17 no.2
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    • pp.169-173
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    • 1999
  • The present study was undertaken to survey the infection status of Metagonimus sp. metacercariae in freshwater fishes from Tong river located in Kangwon Province, a total of 178 freshwater fishes of 11 species were collected by a fish net and traps from the end of September to early October 1998. They were brought to the laboratory and examined under a stereomicroscope after artificial digestion with pepsin-HCI solution for one hour. Ten out of eleven species of freshwater fishes examined were found to contain metacercariae of Metagonimus sp. The most frequently infected fish was Liobagrus andersoni Regan 91.7% (11 of 12 fishes), followed by Gobiobotia breviburba Mori 75.0% (6 of 8 fishes), Zacco temmincki 66.2% (49 of 74 fishes), Cobitis koreensis Kim 50.0% (1 of 2 fishes), Microphysogobio longidorsails Mori 42.9% (9 of 21 fishes), Cobitis rotundicudata Wakiya et Mori 33.3% (2 of 6 fishes), Hemibarbus longirostris 33.3% (1 of 3 fishes), Pungtungia tenuicorpus 30.0% (3 of 10 fishes), Coreoleuciscus splenddus Mori 28.6% (4 of 14 fishes), Coreoperca herri Herzeanstein 11.1% (1 of 9 fishes) respectively Metagonimus metacercariae was not found from Moroco kumgangensis Uchida of freshwater fish. The total number of Metagonimus sp. metacercariae was 81, 17, 216, 1, 14, 2, 1, 4, 10, 1, respectively. Infection rates of Metagonimus sp. in the five districts was shown as follows : Chongson-up Kyulam-ri 50.0% (12 of 24 fishes), Chongson-up Kasu-ri 34.0% (17 of 50 fishes), Shindong-up Unchi-ri 56.0% (14 of 25 fishes), Shingdong-up Kosong-ri 57.1% (20 of 35 fishes), Shingdong-up Duckchon-ri 54.5% (24 of 44 fishes) respectively. Infection rate of freshwater fish was 48.9% (87 of 178 fishes) and from the results obtained in this survey, it was confirmed that freshwater fishes from Tong river was infected with metacercariae of Metagonimus sp.

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Reestablishment of Approval Toxin Amount in Paralytic Shellfish Poison-Infested Shellfish 3. Thermal Resistance of Paralytic Shellfish Poison (마비성 패류독 허용기준치 재설정을 위한 연구 3. 마비성 패류독의 내열성)

  • 신일식;김영만
    • Journal of Food Hygiene and Safety
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    • v.13 no.2
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    • pp.143-148
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    • 1998
  • The purpose of this study was to determine the kinetics of paralytic shellfish poison (PSP) destruction at various temperature. The toxic digestive gland homogenate of blue mussel (Mytilus edulis), PSP crude toxin, gonyautoxin group and saxitoxin group were heated at temperature ranging from 90 to $120^{\circ}C$, and then the toxicities were measured in samples heated for various time intervals. The rate constant (k) of the toxic digestive gland homogenate, PSP crude toxin, gonyautoxin group and saxitoxin group were $3.28{\times}10^{-2},\;1.20{\times}10^{-2},\;5.88{\times}10^{-2}\;and\;2.58{\times}10^{-2}\;at\;120^{\circ}C$, respectively. The decimal reduction time (D-value) of the toxic digestive gland homogenate, PSP crude toxin, gonyautoxin group and saxitoxin group were 70, 192, 39 and 89 at $120^{\circ}C$, respectively. These results indicate that PSP crude toxin is most heat-stable of 4 types of PSP toxins and PSP toxin are more heat-stable than food poisoning bacteria and spores. The retorting condition to reduce PSP toxicity below quarantine limit ($80\;\mu\textrm{g}/100\;g$ in Korea and America, 4 MU/g in Japan) could be calculated by rate constant. For example, the digestive gland homogenate having a initial toxicity of $200\;\mu\textrm{g}/100\;g$ could have toxicity below quarantine limit when heated at $90^{\circ}C$ for 129 min., $100^{\circ}C$ for 82 min., $110^{\circ}C$ for 48 min. and $120^{\circ}C$ for 28 min. These results suggest that commercial retorting condition ($115^{\circ}C$ for 70 min) in Korea is enough to reduce toxicity below quarantine limit from initial toxicity of $200\;\mu\textrm{g}/100\;g$. From these results, the quarantine limit of PSP-infested shellfish for canning can be level up to raw score of $200\;\mu\textrm{g}/100\;g$.

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Evaluation of Available Soil Silicon Extracting Procedures for Oriental Melon (참외 시설재배 토양에 대한 유효규산 추출방법 비교)

  • Cho, Hyun-Jong;Choe, Hui-Yeol;Lee, Yong-Woo;Chung, Jong-Bae
    • Korean Journal of Soil Science and Fertilizer
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    • v.37 no.4
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    • pp.251-258
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    • 2004
  • Soil testing for silicon (Si) in the upland soils has not been sufficiently investigated. The objective of this study was to identify a suitable Si extraction method for upland soils of oriental melon (Cucumis melo L.). Thirty-eight surface soil samples and matured leaf samples were collected from plastic film houses in Sungju, Gyeongbuk province. In the laboratory, six different methods were used for extracting Si from the soils. The methods included 0.5 N HCl extraction, 1 N sodium acetate buffer (PH 4.0) extraction, citric acid 1% extraction, water extraction, Tiis buffer pH 7.0 extraction, and extraction after incubation with water for 1 week. The concentration of dissolved Si in soil extracts from all methods was determined colorimetrically. With 1 N sodium acetate buffer extraction, as the available soil Si increased, the concentration ofSi in oriental melon leaf increased until around $14g\;SiO_2\;kg^{-1}$ was reached in the form of a saturation curve. Also, among the methods studied, extraction with 1 N sodium acetate buffer was the only method provided a significant linear correlation with oriental melon leaf Si content in the range of extractable soil Si lower than the level which inducing Si saturation in oriental melon leaf. These results indicate that 1 N sodium acetate buffer extraction procedure is the best soil Si test method for upland soils of oriental melon. This sodium acetate buffer extraction procedure is rapid and quite well acquainted with scientists and farmers, since the method has been used for routine paddy soil testing.

Strain Improvement of Leuconostoc mesenteroides as a Acid-Resistant Mutant and Effect on Kimchi fermentation as a Starter (Leuconostoc mesenteroides의 내산성 변이주의 김치발효에 미치는 효과)

  • Kim Young-Hwan;Kim Hee-Zoong;Kim Ji-Young;Choi Tae-Bu;Kang Sang-Mo
    • Microbiology and Biotechnology Letters
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    • v.33 no.1
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    • pp.41-50
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    • 2005
  • An organic acid tolerance mutant (M-200) was obtained from Leuconostoc mesenteroides KCCM 35471, followed by the screening procedure using a specific organic acid medium (lactic acid: acetic acid, 2:1). The characteristics of the acid tolerance M-200 and the wild type LM-W were examined at various temperature and pH ranges $(l0-30^{\circ}C$ of temp, 3.5-4.5 of pH). The growth of strain M-200 at HCl adjusted medium $(10^{\circ}C\;and\;pH 3.5)$ was observed. In the case of organic acid adjusted medium, the strain showed its growth at the pH range of 3.8. When the strain M-200 was used as a starter for Kimchi fermentation, a constant acid level (0.55) was observed during the whole fermentation period. This result indicates that the strain produces a proper level of acid content for the Kimchi fermentation. This result also indicates that the edible period of Kimchi can be extended to 3.5 fold compare to the result obtained from the LM-W used Kimchi fermentation. However the excess use of the strain M-200 showed the inhibition of growth of Lactobacillus plantarum, low lactic acid level content and low level of organoleptic test. In the case of organic acid content during the Kimchi fermentation, the strain M-200 showed relatively low production rate compare to the wild type (M-200: 3.5 mg/L at 21 days of fermentation, LM-W: 7 mg/L at 21 days of fermentation). Therefore a mixed Kimchi starter containing M-200 and other strains probably maintain a good Kimchi quality during the fermentation.

Learning Material Bookmarking Service based on Collective Intelligence (집단지성 기반 학습자료 북마킹 서비스 시스템)

  • Jang, Jincheul;Jung, Sukhwan;Lee, Seulki;Jung, Chihoon;Yoon, Wan Chul;Yi, Mun Yong
    • Journal of Intelligence and Information Systems
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    • v.20 no.2
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    • pp.179-192
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    • 2014
  • Keeping in line with the recent changes in the information technology environment, the online learning environment that supports multiple users' participation such as MOOC (Massive Open Online Courses) has become important. One of the largest professional associations in Information Technology, IEEE Computer Society, announced that "Supporting New Learning Styles" is a crucial trend in 2014. Popular MOOC services, CourseRa and edX, have continued to build active learning environment with a large number of lectures accessible anywhere using smart devices, and have been used by an increasing number of users. In addition, collaborative web services (e.g., blogs and Wikipedia) also support the creation of various user-uploaded learning materials, resulting in a vast amount of new lectures and learning materials being created every day in the online space. However, it is difficult for an online educational system to keep a learner' motivation as learning occurs remotely, with limited capability to share knowledge among the learners. Thus, it is essential to understand which materials are needed for each learner and how to motivate learners to actively participate in online learning system. To overcome these issues, leveraging the constructivism theory and collective intelligence, we have developed a social bookmarking system called WeStudy, which supports learning material sharing among the users and provides personalized learning material recommendations. Constructivism theory argues that knowledge is being constructed while learners interact with the world. Collective intelligence can be separated into two types: (1) collaborative collective intelligence, which can be built on the basis of direct collaboration among the participants (e.g., Wikipedia), and (2) integrative collective intelligence, which produces new forms of knowledge by combining independent and distributed information through highly advanced technologies and algorithms (e.g., Google PageRank, Recommender systems). Recommender system, one of the examples of integrative collective intelligence, is to utilize online activities of the users and recommend what users may be interested in. Our system included both collaborative collective intelligence functions and integrative collective intelligence functions. We analyzed well-known Web services based on collective intelligence such as Wikipedia, Slideshare, and Videolectures to identify main design factors that support collective intelligence. Based on this analysis, in addition to sharing online resources through social bookmarking, we selected three essential functions for our system: 1) multimodal visualization of learning materials through two forms (e.g., list and graph), 2) personalized recommendation of learning materials, and 3) explicit designation of learners of their interest. After developing web-based WeStudy system, we conducted usability testing through the heuristic evaluation method that included seven heuristic indices: features and functionality, cognitive page, navigation, search and filtering, control and feedback, forms, context and text. We recruited 10 experts who majored in Human Computer Interaction and worked in the same field, and requested both quantitative and qualitative evaluation of the system. The evaluation results show that, relative to the other functions evaluated, the list/graph page produced higher scores on all indices except for contexts & text. In case of contexts & text, learning material page produced the best score, compared with the other functions. In general, the explicit designation of learners of their interests, one of the distinctive functions, received lower scores on all usability indices because of its unfamiliar functionality to the users. In summary, the evaluation results show that our system has achieved high usability with good performance with some minor issues, which need to be fully addressed before the public release of the system to large-scale users. The study findings provide practical guidelines for the design and development of various systems that utilize collective intelligence.

The Reinforcing Mechanism of Sustaining Participations in Open Source Software Developers: Based on Social Identity Theory and Organizational Citizenship Behavior Theory (오픈 소스 개발자들의 참여 의도 강화 기제 및 참여 지속 의도에 관한 연구: 사회 정체성 이론과 조직시민행동 이론에 기반하여)

  • Choi, Junghong;Choi, Joohee;Lee, Hye Sun;Hwangbo, Hwan;Lee, Inseong;Kim, Jinwoo
    • Asia pacific journal of information systems
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    • v.23 no.3
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    • pp.1-23
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    • 2013
  • Open Source Software Development (OSSD) differentiates itself from traditional closed software development in that it reveals its source codes online and allows anyone to participate in projects. Even though its success was in doubt, many of the open collaborative working models produced successful results. Academia started to get interested in how developers are willing to participate even when there are no extrinsic rewards for their efforts. Many studies tried to explain developers' motivations, and the pursuit of ideology, reputation, and altruism are found to be the answers. Those studies, however, focused mostly on how the first contribution is made out of a certain motivation. Nowadays, OSSD reaches at its maturity and 70% of professional developers have used or utilized open source software or code in their works. As the proportion of people experiencing OSS, the accounts from previous studies are expected to be weakened. Also, extant literature fails to explain how the motivation of participating in OSS evolves over time and experiences. Given that changing over time or over experiences is the natural in the perception of motivation, studies in an attempt to understand how the motivation changes or evolves are in need. In this study, we aimed to explain how the perception about OSS from past usage or related experiences leads to the intention to sustain OSS participations. By doing so, we try to bridge the gap between previous studies and the actual phenomenon. We argued that perceived instrumentality about OSS learned from past experiences will first affect the formation of organizational identity towards general OSS community. And once the organizational identity is formed, it will affect the one's following behaviors related to OSS development, most likely to sustain the favoring stance toward OSS community. Our research distinguishes itself from previous one in that it divides the paths from organizational identity formed to the intention to sustain the voluntary helping behaviors, by altruistic and conforming intentions. Drawing on this structural model, we could explain how organizational identity engages in forming the sustaining intention from past experiences, and that the intention to help at individual level and organizational level works at different level in OSS community. We grounded our arguments on Social identity theory and Organizational Citizenship theory. We examined our assumption by constructing a structural equation model (SEM) and had 88 developers to answer our online surveys. The result is analyzed by PLS (partial least square) method. Consequently, all paths but one in our model are supported, the one which assumed the association between perceived instrumentality and altruistic intention. Our results provide directions in designing online collaborative platforms where open access collaboration is meant to occur. Theoretically, our study suggests that organizational citizenship behavior can occur from organizational identity, even in bottom-up organizational settings. More specifically, we also argue to consider both organizational level and individual level of motivation in inducing sustained participations within the platforms. Our result can be interpreted to indicate the importance of forming organizational identity in sustaining the participatory behaviors. It is because there was no direct association between perceived instrumentality from past experiences and altruistic behavior, but the perception of organizational identity bridges the two constructs. This means that people with no organizational identity can sustain their participations through conforming intention from only the perception of instrumentality, but it needs little more than that for the people to feel the intention to directly help someone in the community-first to form the self-identity as a member of the given community.

Clinical Study of Corrosive Esophagitis (부식성 식도염에 관한 임상적 고찰)

  • 이원상;정승규;최홍식;김상기;김광문;홍원표
    • Proceedings of the KOR-BRONCHOESO Conference
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    • pp.6-7
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    • 1981
  • With the improvement of living standard and educational level of the people, there is an increasing awareness about the dangers of toxic substances and lethal drugs. In addition to the above, the governmental control of these substances has led to a progressive decrease in the accidents with corrosive substances. However there are still sporadic incidences of suicidal attempts with the substances due to the unbalance between the cultural development in society and individual emotion. The problem is explained by the fact that there is a variety of corrosive agents easily available to the people due to the considerable industrial development and industrialization. Salzen(1920), Bokey(1924) were pioneers on the subject of the corrosive esophagitis and esophageal stenosis by dilatation method. Since then there had been a continuing improvement on the subject with researches on various acid(Pitkin, 1935, Carmody, 1936) and alkali (Tree, 1942, Tucker, 1951) corrosive agents, and the use of steroid (Spain, 1950) and antibiotics. Recently, early esophagoscopic examination is emphasized on the purpose of determining the way of the treatment in corrosive esophagitis patients. In order to find the effective treatment of such patients in future, the authors selected 96 corrosive esophagitis patients who were admitted and treated at the ENT department of Severance hospital from 1971 to March, 1981 to attempt a clinical study. 1. Sex incidence……male: female=1 : 1.7, Age incidence……21-30 years age group; 38 cases (39.6%). 2. Suicidal attempt……80 cases(83.3%), Accidental ingestion……16 cases (16.7%). Among those who ingested the substance accidentally, children below ten years were most numerous with nine patients. 3. Incidence acetic acid……41 cases(41.8%), lye…20 cases (20.4%), HCI……17 cases (17.3%). There was a trend of rapid rise in the incidence of acidic corrosive agents especially acetic acid. 4. Lavage……57 cases (81.1%). 5. Nasogastric tube insertion……80 cases (83.3%), No insertion……16 cases(16.7%), late admittance……10 cases, failure…4 cases, other……2 cases. 6. Tracheostomy……17 cases(17.7%), respiratory problems(75.0%), mental problems (25.0%). 7. Early endoscopy……11 cases(11.5%), within 48 hours……6 cases (54.4%). Endoscopic results; moderate mucosal ulceration…8 cases (72.7%), mild mucosal erythema……2 cases (18.2%), severe mucosal ulceration……1 cases (9.1%) and among those who took early endoscopic examination; 6 patients were confirmed mild lesion and so they were discharged after endoscopy. Average period of admittance in the cases of nasogastric tube insertion was 4 weeks. 8. Nasogastric tube indwelling period……average 11.6 days, recently our treatment trend in the corrosive esophagitis patients with nasogastric tube indwelling is determined according to the finding of early endoscopy. 9. The No. of patients who didn't given and delayed administration of steroid……7 cases(48.9%): causes; kind of drug(acid, unknown)……12 cases, late admittance……11 cases, mild case…9 cases, contraindication……7 cases, other …8 cases. 10. Management of stricture; bougienage……7 cases, feeding gastrostomy……6 cases, other surgical management……4 cases. 11. Complication……27 cases(28.1%); cardio-pulmonary……10 cases, visceral rupture……8 cases, massive bleeding……6 cases, renal failure……4 cases, other…2 cases, expire and moribund discharge…8 cases. 12. No. of follow-up case……23 cases; esophageal stricture……13 cases and site of stricture; hypopharynx……1 case, mid third of esophagus…5 cases, upper third of esophagus…3 cases, lower third of esophagus……3 cases pylorus……1 case, diffuse esophageal stenosis……1 case.

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The studies on wrinkle recovery improvement for silk fabrics (견직물의 방추성 개선연구)

  • 김병호;정진영
    • Journal of Sericultural and Entomological Science
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    • no.11
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    • pp.23-29
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    • 1970
  • This experiment is to improve the wrinkle recovery (W.R.) of silk fabrics. The silk fabrics is creased very well, and the crease is the serious defection of it. This experiment is to improve the nature by use of formaldehyde on fabrics. The reagents used were HCl, CH$_3$COOH, CaC$_2$, HCHO, Na$_2$CO$_3$, NH$_4$OH, NaOH and NaHCO$_3$. The silk fabrics was treated, to compare 1 he influence of conditions, by varying the quantities of reagents and the temperature of solution, and the reaction time. The cotton fabrics and the viscose rayon were sunk with the silk at the same condition to be compared the influence. 1) Those of the most suitable temperature to improve for the better W.R. are 75$^{\circ}C$ for silk, 35-45$^{\circ}C$ for cotton, and no particular temperature under 75$^{\circ}C$ for viscose rayon. 2) The W.R. improvements after treated at the temperature of 1) were 11% for silk and 33.4% for cotton. 3) There are the best treating time for every fabrics. They were 60 to 90 min. for viscose rayon when HAC Ras used for solvent. It took, however, 60min. of the best time for silk, 120 min. for cotton, and 40 min. for viscose rayon when acetic anhydride instead of HAC was used. 4) It was possible to improve 16.6% of W.R. for silk at the most suitable treating time, 25.0% for cotton, and 13.3% for viscose rayon. 5) Acetic anhydride was rather more effective to improve W.R. of both silk and viscose rayon than HAC. 6) Treating time was also shorter in case of using acetic anhydride than HAC. 7) The improvement of W.R. were 8.3% for silk at the 10 to 14 ml. of HCHO the best volume, 21. 5% for cotton at 18m!. of HCHO, and 70% of for viscose rayon at 14 to 18ml. of HCHO. 8) The most effective quantity of HCI is 14 ml. for both silk and cotton. The W.R. improvement of silk was 22.2%, and that of cotton 19.5%. 9) The W.R. of 83.3% the best for silk and 61. 6% for cotton were gained when 4.2gr. of NaHCO$_3$ brings down the percent of W.R. for both silk and cotton. 10) The more NaOH and NH$_4$OH as neutralizing agents, the less effectivity of W.R. until the quantities of the reagents are reached to a special range which are 3. 3m!. for silk and 3.3-6.6 ml. for cotton, and then we can see the W.R. increasing as the quantities of reagents are increased. These facts were evident in case of silk and cotton. We can also see with this fact that the reminder of 〔OH$\^$-/〕 neutralizing 〔CH$\^$+/〕in solution makes it possible to treat formaldehyde on fabrics. 11) Low curing temperature was comparatively better for silk, and high temperature better for cotton. 12) The result of this experiment shows that the Improvement of W.R. for silk was possible to 94% which means 22% W.R. increase compared to the untreated silk. This effect also shows that the improvement to W '||'&'||' W (wash and wear) of silk will be possible.

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A Study on Preparation of 3'-$[^{18}F]$Fluoro-3'-deoxythymidine and Its Biodistribution in 9L Glioma Bearing Rats (3'-$[^{18}F]$Fluoro-3'-deoxythymidine의 합성과 9L glioma 세포를 이식한 래트에서의 체내동태에 관한 연구)

  • Shim, Ah-Young;Moon, Byung-Seok;Lee, Tae-Sup;Lee, Kyo-Chul;An, Gwang-Il;Yang, Seung-Dae;Yu, Kook-Hyun;Cheon, Gi-Jeong;Choi, Chang-Woon;Lim, Sang-Moo;Chun, Kwon-Soo
    • Nuclear Medicine and Molecular Imaging
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    • v.40 no.5
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    • pp.263-270
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    • 2006
  • Purpose: Several radioisotope-labeled thymidine derivatives such as $[^{11}C]$thymidine was developed to demonstrate cell proliferation in tumor. But it is difficult to track metabolism with $[^{11}C]$thymidine due to rapid in vivo degradation and its short physical half-life. 3'-$[^{18}F]$fluoro-3'-deoxythymidine ($[^{18}F]$FLT) was reported to have the longer half life of fluorine-18 and the lack of metabolic degradation in vivo. Here, we described the synthesis of the 3'-$[^{18}F]$fluoro-3'-deoxythymidine ($[^{18}F]$FLT) and compared with $([^{18}F]FET)\;and\;([^{18}F]FDG)$ in cultured 9L cell and obtained the biodistribution and PET image in 9L tumor hearing rats. Material and Methods: For the synthesis of $[^{18}F]$FLT, 3-N-tert-butoxycarbonyl-(5'-O-(4,4'-dimet hoxytriphenylmethyl)-2'-deoxy-3'-O-(4-nitrobenzenesulfonyl)-${\beta}$-D-threopentofuranosyl)thymine was used as a FLT precursor, on which the tert-butyloxycarbonyl group was introduced to protect N3-position and nitrobenzenesulfonyl group. Radiolabeling of nosyl substitued precursor with $^{18}F$ was performed in acetonitrile at $120^{\circ}C$ and deproteced with 0.5 N HCI. The cell uptake was measured in cultured 9L glioma cell. The biodistribution was evaluated in 9L tumor bearing rats after intravenous injection at 10 min, 30 min, 60 min and 120 min and obtained PET image 60 minutes after injection. Results: The radiochemical yield was about 20-30% and radiochemical purity was more than 95% after HPLC purification. Cellular uptake of $[^{18}F]$FLT was increased as time elapsed. At 120 min post-injection, the ratios of tumor/blood, tumor/muscle and tumor/brain were $1.61{\pm}0.34,\;1.70{\pm}0.30\;and\;9.33{\pm}2.22$, respectively. The 9L tumor was well visualized at 60 min post injection in PET image. Conclusion: The uptake of $[^{18}F]$FLT in tumor was higher than in normal brain and PET image of $[^{18}F]$FLT was acceptable. These results suggest the possibility of $[^{18}F]$FLT at an imaging agent for brain tumor.

Pareto Ratio and Inequality Level of Knowledge Sharing in Virtual Knowledge Collaboration: Analysis of Behaviors on Wikipedia (지식 공유의 파레토 비율 및 불평등 정도와 가상 지식 협업: 위키피디아 행위 데이터 분석)

  • Park, Hyun-Jung;Shin, Kyung-Shik
    • Journal of Intelligence and Information Systems
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    • v.20 no.3
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    • pp.19-43
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    • 2014
  • The Pareto principle, also known as the 80-20 rule, states that roughly 80% of the effects come from 20% of the causes for many events including natural phenomena. It has been recognized as a golden rule in business with a wide application of such discovery like 20 percent of customers resulting in 80 percent of total sales. On the other hand, the Long Tail theory, pointing out that "the trivial many" produces more value than "the vital few," has gained popularity in recent times with a tremendous reduction of distribution and inventory costs through the development of ICT(Information and Communication Technology). This study started with a view to illuminating how these two primary business paradigms-Pareto principle and Long Tail theory-relates to the success of virtual knowledge collaboration. The importance of virtual knowledge collaboration is soaring in this era of globalization and virtualization transcending geographical and temporal constraints. Many previous studies on knowledge sharing have focused on the factors to affect knowledge sharing, seeking to boost individual knowledge sharing and resolve the social dilemma caused from the fact that rational individuals are likely to rather consume than contribute knowledge. Knowledge collaboration can be defined as the creation of knowledge by not only sharing knowledge, but also by transforming and integrating such knowledge. In this perspective of knowledge collaboration, the relative distribution of knowledge sharing among participants can count as much as the absolute amounts of individual knowledge sharing. In particular, whether the more contribution of the upper 20 percent of participants in knowledge sharing will enhance the efficiency of overall knowledge collaboration is an issue of interest. This study deals with the effect of this sort of knowledge sharing distribution on the efficiency of knowledge collaboration and is extended to reflect the work characteristics. All analyses were conducted based on actual data instead of self-reported questionnaire surveys. More specifically, we analyzed the collaborative behaviors of editors of 2,978 English Wikipedia featured articles, which are the best quality grade of articles in English Wikipedia. We adopted Pareto ratio, the ratio of the number of knowledge contribution of the upper 20 percent of participants to the total number of knowledge contribution made by the total participants of an article group, to examine the effect of Pareto principle. In addition, Gini coefficient, which represents the inequality of income among a group of people, was applied to reveal the effect of inequality of knowledge contribution. Hypotheses were set up based on the assumption that the higher ratio of knowledge contribution by more highly motivated participants will lead to the higher collaboration efficiency, but if the ratio gets too high, the collaboration efficiency will be exacerbated because overall informational diversity is threatened and knowledge contribution of less motivated participants is intimidated. Cox regression models were formulated for each of the focal variables-Pareto ratio and Gini coefficient-with seven control variables such as the number of editors involved in an article, the average time length between successive edits of an article, the number of sections a featured article has, etc. The dependent variable of the Cox models is the time spent from article initiation to promotion to the featured article level, indicating the efficiency of knowledge collaboration. To examine whether the effects of the focal variables vary depending on the characteristics of a group task, we classified 2,978 featured articles into two categories: Academic and Non-academic. Academic articles refer to at least one paper published at an SCI, SSCI, A&HCI, or SCIE journal. We assumed that academic articles are more complex, entail more information processing and problem solving, and thus require more skill variety and expertise. The analysis results indicate the followings; First, Pareto ratio and inequality of knowledge sharing relates in a curvilinear fashion to the collaboration efficiency in an online community, promoting it to an optimal point and undermining it thereafter. Second, the curvilinear effect of Pareto ratio and inequality of knowledge sharing on the collaboration efficiency is more sensitive with a more academic task in an online community.