1,720,959 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
Chimie de surface de nanocristaux fluorescents pour l’imagerie biologique
No full textSemiconductor nanocrystals (or Quantum Dots, QDs) have unique optical properties that make them interesting probes for biological imaging. Thanks to their high quantum fluorescence yields, they are particularly promising for short-infrared fluorescence imaging, which is a spectral domain that allows a good deep spatial resolution in biological tissues. In this PhD, our goal is to study specialy the surface chemistry of QDs in order to optimize their behavior in complex biological medium and to develop functional pH or enzymatic activity imaging probes. The use of nanoparticles (NP) in vivo requires to reduce the formation of a protein corona adsorbed on their surface. It is possible to use so-called "stealth" polymers to limit this adsorption, and avoid their recognition by the immune system. In this PhD we compare the stealth properties of QDs coated with block polymer ligands with different zwitterions. We have shown, particularly, that poly(sulfobetaine) coated QDs allows a complete elimination of protein adsorption in serum, unlike those covered with carboxybetaine or phosphorylcholine. These results are correlated with the diffusion of these QDs in the cytoplasm of living cells. Thanks to the surface chemistry of QDs, it is also possible to design functional probes, for example by modulating their fluorescence by an energy transfer under the action of a biochemical factor. Thus, in this PhD, we demonstrate two concepts using QDs for short or visible infrared pH imaging, developing different pH-sensitive surface chemistries in order to modulate their interaction with gold NPs.Les nanocristaux de semiconducteurs (ou Quantum Dots, QD) possèdent des propriétés optiques uniques qui en font des sondes intéressantes pour l’imagerie biologique. Ils sont particulièrement prometteurs pour l’imagerie de fluorescence dans l’infrarouge court, permettant de conserver une bonne résolution spatiale en profondeur dans les tissus biologiques. Dans cette thèse, l’objectif est d’étudier tout particulièrement la chimie de surface des QD afin d’optimiser leur comportement en milieu biologique et de développer des sondes fonctionnelles d’imagerie du pH et d’activité enzymatique. L’utilisation de nanoparticules (NP) in vivo nécessite de minimiser la formation d’une couronne de protéines adsorbées à leur surface. Il est possible d’utiliser pour cela des polymères dits « furtifs » pour limiter cette adsorption et éviter leur reconnaissance par le système immunitaire. Dans cette thèse, nous comparons les propriétés de furtivité de QD recouverts de ligands polymères comportant différents zwitterions. Nous montrons que les QD recouverts de poly(sulfobétaïne) permettent une élimination complète de l’adsorption de protéines, contrairement à ceux recouverts d’autres bétaïnes. Ces résultats sont corrélés à la diffusion de ces QD dans le cytoplasme de cellules vivantes. La chimie de surface des QD permet également de concevoir des sondes fonctionnelles, par exemple en modulant leur fluorescence par transfert d’énergie sous l’action d’un facteur biochimique. Ainsi, nous démontrons deux concepts de QD pour l’imagerie du pH dans le visible ou l’infrarouge court, en développant différentes chimies de surface sensibles au pH pour moduler leur interaction avec des NP d’or
Chimie de surface de nanocristaux fluorescents pour l’imagerie biologique
No full textSemiconductor nanocrystals (or Quantum Dots, QDs) have unique optical properties that make them interesting probes for biological imaging. Thanks to their high quantum fluorescence yields, they are particularly promising for short-infrared fluorescence imaging, which is a spectral domain that allows a good deep spatial resolution in biological tissues. In this PhD, our goal is to study specialy the surface chemistry of QDs in order to optimize their behavior in complex biological medium and to develop functional pH or enzymatic activity imaging probes. The use of nanoparticles (NP) in vivo requires to reduce the formation of a protein corona adsorbed on their surface. It is possible to use so-called "stealth" polymers to limit this adsorption, and avoid their recognition by the immune system. In this PhD we compare the stealth properties of QDs coated with block polymer ligands with different zwitterions. We have shown, particularly, that poly(sulfobetaine) coated QDs allows a complete elimination of protein adsorption in serum, unlike those covered with carboxybetaine or phosphorylcholine. These results are correlated with the diffusion of these QDs in the cytoplasm of living cells. Thanks to the surface chemistry of QDs, it is also possible to design functional probes, for example by modulating their fluorescence by an energy transfer under the action of a biochemical factor. Thus, in this PhD, we demonstrate two concepts using QDs for short or visible infrared pH imaging, developing different pH-sensitive surface chemistries in order to modulate their interaction with gold NPs.Les nanocristaux de semiconducteurs (ou Quantum Dots, QD) possèdent des propriétés optiques uniques qui en font des sondes intéressantes pour l’imagerie biologique. Ils sont particulièrement prometteurs pour l’imagerie de fluorescence dans l’infrarouge court, permettant de conserver une bonne résolution spatiale en profondeur dans les tissus biologiques. Dans cette thèse, l’objectif est d’étudier tout particulièrement la chimie de surface des QD afin d’optimiser leur comportement en milieu biologique et de développer des sondes fonctionnelles d’imagerie du pH et d’activité enzymatique. L’utilisation de nanoparticules (NP) in vivo nécessite de minimiser la formation d’une couronne de protéines adsorbées à leur surface. Il est possible d’utiliser pour cela des polymères dits « furtifs » pour limiter cette adsorption et éviter leur reconnaissance par le système immunitaire. Dans cette thèse, nous comparons les propriétés de furtivité de QD recouverts de ligands polymères comportant différents zwitterions. Nous montrons que les QD recouverts de poly(sulfobétaïne) permettent une élimination complète de l’adsorption de protéines, contrairement à ceux recouverts d’autres bétaïnes. Ces résultats sont corrélés à la diffusion de ces QD dans le cytoplasme de cellules vivantes. La chimie de surface des QD permet également de concevoir des sondes fonctionnelles, par exemple en modulant leur fluorescence par transfert d’énergie sous l’action d’un facteur biochimique. Ainsi, nous démontrons deux concepts de QD pour l’imagerie du pH dans le visible ou l’infrarouge court, en développant différentes chimies de surface sensibles au pH pour moduler leur interaction avec des NP d’or
Surface chemistry of fluorescent nanocrystals for biological imaging
No full textLes nanocristaux de semiconducteurs (ou Quantum Dots, QD) possèdent des propriétés optiques uniques qui en font des sondes intéressantes pour l’imagerie biologique. Ils sont particulièrement prometteurs pour l’imagerie de fluorescence dans l’infrarouge court, permettant de conserver une bonne résolution spatiale en profondeur dans les tissus biologiques. Dans cette thèse, l’objectif est d’étudier tout particulièrement la chimie de surface des QD afin d’optimiser leur comportement en milieu biologique et de développer des sondes fonctionnelles d’imagerie du pH et d’activité enzymatique. L’utilisation de nanoparticules (NP) in vivo nécessite de minimiser la formation d’une couronne de protéines adsorbées à leur surface. Il est possible d’utiliser pour cela des polymères dits « furtifs » pour limiter cette adsorption et éviter leur reconnaissance par le système immunitaire. Dans cette thèse, nous comparons les propriétés de furtivité de QD recouverts de ligands polymères comportant différents zwitterions. Nous montrons que les QD recouverts de poly(sulfobétaïne) permettent une élimination complète de l’adsorption de protéines, contrairement à ceux recouverts d’autres bétaïnes. Ces résultats sont corrélés à la diffusion de ces QD dans le cytoplasme de cellules vivantes. La chimie de surface des QD permet également de concevoir des sondes fonctionnelles, par exemple en modulant leur fluorescence par transfert d’énergie sous l’action d’un facteur biochimique. Ainsi, nous démontrons deux concepts de QD pour l’imagerie du pH dans le visible ou l’infrarouge court, en développant différentes chimies de surface sensibles au pH pour moduler leur interaction avec des NP d’or.Semiconductor nanocrystals (or Quantum Dots, QDs) have unique optical properties that make them interesting probes for biological imaging. Thanks to their high quantum fluorescence yields, they are particularly promising for short-infrared fluorescence imaging, which is a spectral domain that allows a good deep spatial resolution in biological tissues. In this PhD, our goal is to study specialy the surface chemistry of QDs in order to optimize their behavior in complex biological medium and to develop functional pH or enzymatic activity imaging probes. The use of nanoparticles (NP) in vivo requires to reduce the formation of a protein corona adsorbed on their surface. It is possible to use so-called "stealth" polymers to limit this adsorption, and avoid their recognition by the immune system. In this PhD we compare the stealth properties of QDs coated with block polymer ligands with different zwitterions. We have shown, particularly, that poly(sulfobetaine) coated QDs allows a complete elimination of protein adsorption in serum, unlike those covered with carboxybetaine or phosphorylcholine. These results are correlated with the diffusion of these QDs in the cytoplasm of living cells. Thanks to the surface chemistry of QDs, it is also possible to design functional probes, for example by modulating their fluorescence by an energy transfer under the action of a biochemical factor. Thus, in this PhD, we demonstrate two concepts using QDs for short or visible infrared pH imaging, developing different pH-sensitive surface chemistries in order to modulate their interaction with gold NPs
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
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
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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