1,721,042 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
A Versatile Toolbox for Multiplexed Protein Micropatterning by Laser Lithography
No full textPhotocleavable oligohistidine peptides (POHP) allow in situ spatial organization
of multiple His-tagged proteins onto surfaces functionalized with tris(nitrilotriacetic
acid) (tris-NTA). Here, a second generation of POHPs is presented with improved
photoresponse and site-specifi c covalent coupling is introduced for generating
stable protein assemblies. POHPs with different numbers of histidine residues and a
photocleavable linker based on the 4,5-dimethoxy-o-nitrophenyl ethyl chromophore
are prepared. These peptides show better photosensitivity than the previously
used o-nitrophenyl ethyl derivative. Effi cient and stable caging of tris-NTAfunctionalized
surfaces by POHPs comprising 12 histidine residues is demonstrated
by multiparameter solid-phase detection techniques. Laser lithographic uncaging
by photofragmentation of the POHPs is possible with substantially reduced
photodamage as compared to previous approaches. Thus, in situ micropatterning
of His-tagged proteins under physiological conditions is demonstrated for the fi rst
time. In combination with a short peptide tag for a site-specifi c enzymatic coupling
reaction, covalent immobilization of multiple proteins into target micropatterns is
possible under physiological conditions.Gropeanu, M.; Bhagawati, M.; Gropeanu, RA.; Rodríguez Muñiz, GM.; Sundaram, S.; Piehler, J.; Campo, AD. (2013). A Versatile Toolbox for Multiplexed Protein Micropatterning by Laser Lithography. Small. 9(6):838-845. doi:10.1002/smll.201201901S83884596Van den Heuvel, M. G. L., & Dekker, C. (2007). Motor Proteins at Work for Nanotechnology. Science, 317(5836), 333-336. doi:10.1126/science.1139570You, C., Bhagawati, M., Brecht, A., & Piehler, J. (2009). Affinity capturing for targeting proteins into micro and nanostructures. Analytical and Bioanalytical Chemistry, 393(6-7), 1563-1570. doi:10.1007/s00216-008-2595-6Hyun, J., Zhu, Y., Liebmann-Vinson, A., Beebe,, T. P., & Chilkoti, A. (2001). Microstamping on an Activated Polymer Surface: Patterning Biotin and Streptavidin onto Common Polymeric Biomaterials. Langmuir, 17(20), 6358-6367. doi:10.1021/la010695xPark, J. P., Lee, S. J., Park, T. J., Lee, K.-B., Choi, I. S., Lee, S. Y., … Chung, B. H. 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Analytical Chemistry, 75(18), 4740-4746. doi:10.1021/ac0344438Agarwal, G., Naik, R. R., & Stone, M. O. (2003). Immobilization of Histidine-Tagged Proteins on Nickel by Electrochemical Dip Pen Nanolithography. Journal of the American Chemical Society, 125(24), 7408-7412. doi:10.1021/ja029856pTinazli, A., Tang, J., Valiokas, R., Picuric, S., Lata, S., Piehler, J., … Tampé, R. (2005). High-Affinity Chelator Thiols for Switchable and Oriented Immobilization of Histidine-Tagged Proteins: A Generic Platform for Protein Chip Technologies. Chemistry - A European Journal, 11(18), 5249-5259. doi:10.1002/chem.200500154(s. f.). doi:10.1021/ac060024Valiokas, R., Klenkar, G., Tinazli, A., Tampé, R., Liedberg, B., & Piehler, J. (2006). Differential Protein Assembly on Micropatterned Surfaces with Tailored Molecular and Surface Multivalency. ChemBioChem, 7(9), 1325-1329. doi:10.1002/cbic.200600176Maury, P., Escalante, M., Péter, M., Reinhoudt, D. N., Subramaniam, V., & Huskens, J. (2007). 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Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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
Monofunctional stealth nanoparticle for unbiased single molecule tracking inside living cells
No full textOn the basis of a protein cage scaffold, we have systematically explored intracellular application of nanoparticles for single molecule studies and discovered that recognition by the autophagy machinery plays a key role for rapid metabolism in the cytosol. Intracellular stealth nanoparticles were achieved by heavy surface PEGylation. By combination with a generic approach for nanoparticle monofunctionalization, efficient labeling of intracellular proteins with high fidelity was accomplished, allowing unbiased long-term tracking of proteins in the outer mitochondrial membrane
Integrated optical Mach-Zehnder interferometer as simazine immunoprobe
No full textImmunoassay has become a versatile tool in several fields of analytical chemistry. We describe the characterization and the application of different integrated optical channel waveguide Mach-Zehnder interferometers (MZIs) as label-free immunoprobes. The performance of the classical MZI is compared with that of a modified structure which incorporates a 3x3 coupler. Characterization of the devices demonstrates a dramatic improvement gained by using the 3x3 coupler. Two main advantages are achieved by the modified device. First, the possibility of referencing the output signal allows the elimination of signal fluctuations due to coupling and light-source instabilities. An increase of the signal-to-noise ratio by a factor of up to 10 is achieved. Secondly, the phase shift between the three outputs allows unambiguous detection with optimum sensitivity. For the detection of the herbicide simazine, the functional properties of the transducer surface are optimized by an appropriate chemical modification. Using this improved device, a simazine immunoassay has been carried out with a test midpoint of 0.3 ppb and a detection limit of approximately 0.1 ppb. The excellent performance, established manufacturing techniques and the potential for simplification and parallelization make the device attractive for further development
Integrated optical directional coupler sensor for pesticide analysis
No full textIntegrated optical transducers for the measurement of interactions between biological molecules and the specific detection of chemical and biochemical species are the subject of growing interest. Targeted applications include environmental monitoring, industrial process control and medical diagnostics. Integrated optical devices are capable of delivering the high detection sensitivity achievable through optical techniques in a compact format, and offer the potential for the detection of several analytes simultaneously through the fabrication of multiple transducers on a single chip. Here we describe the use of a new type of integrated optical sensor applied to the detection of low concentrations of the pesticide atrazine in aqueous solution. The transducer is based on a planar waveguide directional coupler structure fabricated by Ag+-Na+ ion-exchange in a low-index glass substrate. This sensor has the advantage of differential outputs, which gives improved signal-to-noise characteristics and offers the potential for the simultaneous measurement of the real and imaginary parts of the refractive indices of bulk or thin-film analytes
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