1,720,984 research outputs found
Fabrication of periodic arrays of metallic nanoparticles by block copolymer templates on HfO2 substrates
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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
Doping of silicon by phosphorus end-terminated polymers: Drive-in and activation of dopants
Full text linkAn effective doping technology for the precise control of P atom injection and activation into a semiconductor substrate is presented. Polystyrene polymers with a narrow molecular weight distribution and end-terminated with a P containing moiety are used to build up a phosphorus δ-layer to be used as the dopant source. P atoms are efficiently injected into the Si substrate by high temperature (900-1250 °C) thermal treatments. Temperature dependent (100-300 K) resistivity and Hall measurements in the van der Pauw configuration demonstrate high activation rates (ηa > 80%) of injected P atoms. This bottom-up approach holds promise for the development of a mild technology for efficient doping of semiconductors
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
Resistive Switching in High-Density Nanodevices Fabricated by Block Copolymer Self-Assembly
Full text linkBipolar resistive switching Memories based on metal oxides offer a great potential in terms of Simple process integration, memory performance, and scalability. In view of ultrahigh density memory applications, a reduced device size is not the only requirement, as the distance between different devices is a key parameter. By exploiting a bottom-up fabrication approach based on block copolymer self-assembling, we obtained the parallel production of bilayer Pt/Ti top electrodes arranged in periodic arrays Over the HfO2/TiN surface, building:memory devices with a diameter of 28 nm and a density of 5 x 10(10) devices/cm(2). For an electrical characterization, the sharp conducting tip of an atomic force microscope was adopted for a selective addressing of the nanodevices. The presence of devices showing high Conductance in the initial state was directly connected with scattered leakage current paths in the bare Oxide film, while with bipolar voltage operations we obtained-reversible set/reset transitions irrespective of the conductance variability in the initial state. finally, we disclosed a scalability limit for ultrahigh density memory arrays based on continuous HfO2 thin films, in Which a cross-talk between distinct nanodevices can occur during both set and reset transitions
Doping of silicon with phosphorus end-terminated polymers: source characterization and dopant diffusion in SiO2
No full textA polystyrene homopolymer with narrow molecular weight distribution (Mn= 2.3 ± 0.3 kg mol−1,Đ= 1.05 ± 0.01) and end-terminated with a phosphorus containing moiety has been used to form P δ-layers embedded into a SiO2matrix. The number of P atoms in the δ-layers has been stepwise increased from ∼5 × 1013to ∼1.6 × 1014atoms per cm2by repeated doping cycles. The P δ-layers have been tested as diffusion sources at temperatures ranging from 1000 to 1200 °C for different annealing times, up to 120 s. Variations of the diffusion coefficients with the annealing time have been observed and a clear dependence of diffusion coefficients on the P concentration has been highlighted. These results suggest the presence of two different P species diffusing through the SiO2matrix; an initially fast diffusing P compound and a slow diffusing P atom incorporated into the oxide in a bound form. Collected data provide information about P diffusion in SiO2that is fundamental to the development of predictive models for nanoscale doping processes based on the use of diffusion dopant sources generated by self-limiting reactions of dopant containing molecules onto deglazed or non-deglazed semiconductor substrates
Collective behavior of block copolymer thin films within periodic topographical structures
No full textWe perform a systematic study of the effect of adjacent nanostructures on the confinement of block copolymers (BCP) within pre-patterned trenches in 100 nm thick SiO2 films. Asymmetric PS-b-PMMA BCP with a styrene fraction of 0.71, Mn = 67100 are used. When deposited in the form of thin film, these BCP naturally self-organize upon annealing and form a PS matrix with hexagonally packed PMMA cylinders perpendicularly oriented with respect to the substrate. An accurate study of the confinement of this BCP thin film within isolated trenches is performed as a function of their width (80-260 nm). In this specific configuration the confinement of the BCP thin film within the pre-patterned structures has only been partially achieved. The effect of adjacent trenches on the arrangement of the BCP thin film is investigated using parallel trenches periodically distributed on the surface. The effective confinement of the BCP film is strongly modified by the periodicity of the pre-patterned structures
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
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