1,720,964 research outputs found
Fabrication and characteristics of mesoporous silica and organosilicate thin films
No full text학위논문(박사) - 한국과학기술원 : 신소재공학과, 2005.2, [ xiv, 157 p. ]한국과학기술원 : 신소재공학과
Formation and thermal-induced changes of mesostructures in fluorinated organosilicate films
No full textMesoporous fluorinated organosilicate films were synthesized from tetramethoxysilane and perfluoroalkylsilanes (RO)(3)Si-R' under acidic conditions in the presence of cationic surfactant or triblock copolymer by sol-gel spin-coating. The mesoporous fluorinated organosilicate films made from perfluoroalkylsilanes (PFASs) with long perfluoroalkyl chains, which acted as a template, displayed a hexagonal mesostructure with very low concentration of surfactants, regardless of the kind of surfactants. Although most of the surfactants and organic moieties were decomposed above 550 degrees C, the mesostructure of mesoporous fluorinated organosilicate films was maintained up to 650 degrees C. After calcination at 550 degrees C, their composition was similar to that of mesoporous silica films, and the cylindrical mesostructure was changed to less ordered and broken mesostructure when PFASs with long perfluoroalkyl chains were used. However, the cylindrical mesostructure was maintained when PFASs with short perfluoroalkyl chains were used. Therefore, PFASs with long perfluoroalkyl chains acted as a structure directing agent, and the chain length of PFASs affected the formation of mesostructure and thermal-induced mesostructural change. Also, the increase of calcination temperature caused the change of the composition, mesostructure, and optical property in the mesoporous fluorinated organosilicate films. (C) 2006 Elsevier Inc. All rights reserved.This work was supported by Grant No. R01-2003-000-
10125-0 from the Basic Research Program of the Korea
Science and Engineering Foundation and the Brain Korea
21 project
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Cancer screening with PET and PET/CT in apparently healthy subjects
No full text의학과/석사[한글]연구목적: 무증상 성인을 대상으로 시행된 PET과 PET/CT 검사 결과를 분석하여 이들 검사의 암 발견을 위한 선별검사로서의 유용성을 평가하고자 하였다. 대상 및 방법: 1998년 3월부터 2008년 2월까지 삼성서울병원 건강의학센터에서 건강검진 프로그램의 일부로 시행된 PET과 PET/CT 검사자 중 1년 이상 추적관찰이 이루어진 5091명을 대상으로 판독 유형을 조사하고 판독 상 명확한 결론을 내기 어려워 추가 검사를 권고한 경우를 분석하였다. PET과 PET/CT 시행 후 1년 이내에 암이 확진 된 경우를 조사하여 판독 결과와 비교하고 PET과 PET/CT의 민감도와 특이도를 평가하였다. 결과: PET 또는 PET/CT 검사 시행 후 1년 이내에 암을 진단 받은 경우는 총 86건으로 전체 조사 대상의 1.7%(86/5091)였다. PET과 PET/CT 검사를 합친 전체검사의 민감도는 48.8%였으며 특이도는 81.1%였다. PET 단독검사의 민감도와 특이도는 각각 46.2%, 81.4% 였으며, PET/CT 단독검사의 민감도와 특이도는 각각 75.0%, 78.5%였다. 총 86건의 암 중 11건은 일반적인 건강검진으로는 발견하지 못하였으나 PET과 PET/CT로 발견되었다. 판독에서 암이 의심되었던 경우와 판독에서 암이 의심되지 않았던 경우를 비교하여 보았으나 암 부위, 조직학적 진단, 암 병기 등에서 두 군 사이에 통계학적으로 유의한 차이가 없었다. PET 과 PET/CT 상 양성 혹은 악성의 의미 있는 병변이 의심되거나 양성 및 악성을 구분하기 어려워 추가 검사를 권고한 경우는 전체의 19.3%(981/5091) 였다. 이중에서 두경부 및 상부 위장관 부위에 대한 추가 검사를 권고한 경우가 가장 많았다. 결론: PET과 PET/CT의 올바른 사용을 위해서는 검사에 대한 충분한 이해를 바탕으로 의료인 및 수진자가 현명한 선택을 하도록 하여야 할 것이다.
[영문]Objective: We retrospectively investigated the diagnostic performance of 18F-fluorodeoxyglucose positron emission tomography (PET) and PET/CT for cancer detection in asymptomatic health-check examinees.
Materials and Methods: This study consisted of 5091 PET or PET/CT conducted as part of annual health examination at one hospital from March 1998 to February 2008. To analyze the incidence of cancers, medical records of the subjects were thoroughly reviewed for a follow-up period of one year. The patterns of formal readings of PET and PET/CT were analyzed to assess the sensitivity and specificity for cancer detection. The stage and histopathology of the cancers were evaluated in relation to the results of PET.
Results: Eighty-six cancers (1.7%) were diagnosed within one year after PET or PET/CT. When PET and PET/CT results were combined, the sensitivity was 48.8% and specificity was 81.1% for cancer detection. PET only had a sensitivity of 46.2% and a specificity of 81.4%, and PET/CT only had a sensitivity of 75.0% and a specificity of 78.5% respectively. Eleven cancers were diagnosed only PET or PET/CT. There were no significant differences in cancer site, stage and histopathology between PET positive and PET negative cancers. In 19.3% of formal readings of PET and PET/CT, further evaluation to exclude malignancy or significant disease was recommended. Head and neck area and upper gastrointestinal tract were commonly recommended sites for further evaluation.
Conclusions: More experience and further investigation are needed to overcome limitations of PET and PET/CT for cancer screening.ope
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