1,720,964 research outputs found
Synthesis and characterization of tri(ethylene oxide)-attached poly(amidoamine) dendrimer layers on gold
No full textThis paper describes the synthesis of a tri(ethylene oxide)-attached fourth-generation poly(amidoamine) dendrimer (EO3-dendrimer) and the characterization of its layers on gold. NMR analysis and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry revealed that about 61 amine groups of a G4 PAMAM dendrimer were covalently conjugated with tri(ethylene oxide) units, accounting for a 95% modification level. Layers of the EO3-dendrimer were formed on gold, and the resulting surface was characterized by infrared reflection absorption spectroscopy, ellipsometry, and contact angle goniometry. The EO3-dendrimer resulted in more hydrophilic and less compact layers with no substantial deformation of the molecule during layer formation by virtue of the EO3 units, compared to a PAMAM dendrimer. Interestingly, the specific binding of avidin to the biotinylated layers of the EO3-dendrimer approached a surface density of 5.2 +/- 0.2 ng mm(-2), showing about 92% of full surface coverage. The layers of the EO3-dendrimer were found to be more resistant to nonspecific adsorption of proteins than PAMAM dendrimer layers when bovine serum albumin and serum proteins were tested. (C) 2004 Published by Elsevier Inc
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
인플루엔자 바이러스 RNA의 팬핸들 구조에 대한 자기공명 연구
No full text학위논문(석사) - 한국과학기술원 : 화학과, 1999.2, [ iv, 45p. ]The influenza A viruses which is the most severe and common among the influenza viruses have highly conserved 3`` and 5`` terminal sequences of genomic RNA called panhandle. The conserved panhandle RNA linked by UUCG tetraloop was studied by using NMR spectroscopy. The panhandle is partially double-stranded and involved in initiation and termination of transcription, switching from transcription to replication as well as packaging. The panhandle structure was studied by NMR and molecular modeling by Cheong et al. but the conserved sequences were modified and the results were argued against. This study was initiated to certify this point by using the unmodified RNA which was available by the trans cleaving hammerhead ribozyme.
Overall conformation looks like that of Cheong et al. U3AG/U27UG(I) and A7ACAA/U22GCU(II) have been known to important binding sites of the influenza RNA polymerase. In region (I), U3:G29, A4:U28, G5:U27 are base paired, and the base pair steps seem to deviate slightly from the canonical A form helix. In region (II), there seem to be no base pairs or very weak base pairs, which cannot be identified.
All base pairs except UUCG tetraloop stem melt between 30 and 35 degree in temperature varying experiment implying that the both region (I) and (II) are single-stranded in physiological conditions which were proposed by the fork model. However, since the influenza virus RNA polymerase would stabilize both regions, the in vivo panhandle structure might be different from the in vitro case so it needs further investigation at the stage of polymerase binding.한국과학기술원 : 화학과
인플루엔자 바이러스의 RNA 증진자 및 박테리아의 반메틸화된 DNA와 핵양체 추정 단백질의 구조에 대한 NMR 연구
No full text학위논문(박사) - 한국과학기술원 : 화학과, 2003.8, [ v, 78 p. ]The influenza A virus, a severe pandemic pathogen, has a segmented RNA genome consisting of eight single-stranded RNA molecules. The 5’ and 3’ ends of each RNA segment recognized by the influenza A virus RNA-dependent RNA polymerase direct both transcription and replication of the virus’s RNA genome. Promoter binding by the viral RNA polymerase and formation of an active open complex are prerequisites for viral replication and proliferation. The viral promoter has a significant dynamic nature and an unusual displacement of an adenosine that forms a novel (A-A)ㆍU motif and a C-A mismatch stacked in a helix. The characterized structural features of the promoter imply that the specificity of polymerase binding results from an internal RNA loop. In addition, an unexpected bending (46±10°) near the initiation site suggests the existence of a promoter recognition mechanism similar to that of DNA-dependent RNA polymerase and a possible regulatory function for the terminal structure during open complex formation.
DNA methylation occurs in most organisms from bacteria to mammals and provides a mechanism for epigenetic control of a variety of cellular processes. In Escherichia coli, most of the N6 positions in adenines found in the sequence GATC are methylated by DNA adenine methyltransferase. After DNA replication, the GATC sites exist transiently in the hemimethylated state, and the specific recognition of these hemimethylated GATC sites is essential for several processes, including sequestration of the site of replication initiation by the SeqA protein, strand discrimination in DNA mismatch repair by the MutH protein, and transcription of several genes. The N6-methyl of hemimethylated GATC sites undergoes a slow trans-cis interconversion without disruption of the double helix. The release of tightly bound cation from hemimethylated DNA explains the instability of this structure. In addition, quantitative structural analysis revealed that hemimethylated DNA has unusual...한국과학기술원 : 화학과
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
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