1,720,993 research outputs found
Universality and non-universality in the Ashkin-Teller model
No full textGiuseppe Benfatto, Kensuke Yoshida, Francesco Fucit
Propagation kernel techniques for loop quantum gravity
Full text linkKensuke Yoshida, Giuseppe Benfatto, Francesco Fucit
On some aspects of canonical and covariant approaches to quantum gravity
No full textMauro Carfora, Pietro Menotti, Laurent Freidel, Philippe Roche, Kensuke Yoshida, Carlo Rovell
Structure, properties and proton conductivity of Nafion/[(TiO2)center dot(WO3)(0.148)](psi TiO2) nanocomposite membranes
No full textIn this report are presented the preparation and the characterization of six nanocomposite membranes of formula {Nafion/[(TiO2).(WO3)0.148]yTiO2)} with yTiO2 in the range 0-2.988. These materials are based on Nafion and [(TiO2).(WO3)0.148] nanofiller. The effect of [(TiO2).(WO3)0.148] nanopowders on the structural, thermal, mechanical and electrical properties of {Nafion/[(TiO2).(WO3)0.148]yTiO2} membranes was studied. The water uptake (WU) value of materials was lower than that of pristine Nafion and was correlated with yTiO2. The thermal transitions were investigated by modulated differential scanning calorimetry (MDSC). The mechanical parameters and relaxation processes on temperature were studied by dynamical mechanical analyses (DMA). The FT-IR ATR and mu-Raman vibrational investigations allowed to determine the structure of the hydrophobic polytetrafluoroethylene (PTFE) domains of Nafion and the interactions Nafion-[(TiO2).(WO3)0.148] and Nafion-[H2O] in bulk materials. The analysis of complex conductivity plots were evaluated in the 10-2 Hz-10 MHz and 5-155°C regions. Results indicated that the conductivity of {Nafion/[(TiO2).(WO3)0.148]yTiO2} nanocomposite membrane, with yTiO2 = 1.616, at 135°C, is 5.0 x 10-2 S/cm, while its stability range of conductivity (SRC) extends up to 135°
Broadband dielectric and conductivity spectroscopy of Li-ion conducting three-dimensional hybrid inorganic-organic networks as polymer electrolytes based on poly(ethyleneglycol)400,Zr and Al nodes
No full textThe dielectric and conductivity study of two series of five three-dimensional hybrid inorganic–organic networks as polymer electrolytes (3D-HION-APEs), with formula {Al[O(CH2CH2O)8.7]r/(LiClO4)z}n (1.86 ≤ r ≤ 2.24, 0 ≤ z ≤ 1.06) and {Zr[O(CH2CH2O)8.7]r/(LiClO4)z}n (1.81 ≤ r ≤ 1.99, 0 ≤ z ≤ 0.91) is presented. The real and imaginary components of the complex dielectric permittivity spectra ε* and conductivity spectra s* are measured between −60 ◦C and 80 ◦C. Spectral analysis points out that the conductivity mechanism is determined by two dielectric relaxation events, a and b. The relaxation b
occurs at higher frequencies than a, and is attributed to the segmental motion with characteristic frequency fseg. The relaxation a is attributed to the ionic motion with characteristic frequency fion. The profiles of the direct conductivity sdc and the frequencies fion and fseg vs. the reciprocal temperature
exhibit a Vögel–Tamman–Fülcher (VTF) behavior. The study of the activation energies of the dielectric relaxations a and b allows to determine their relative contribution to the direct conductivity sdc at lower and higher temperatures. The dependence of the VTF parameters vs. the mole-to-mole ratios nLi/nO and nLi/nM (M = Zr, Al) in combination with previous equivalent conductivity studies, allows to identify the role of the ionic species and the metal nodes present in the polymer structure at various salt concentrations. The correlation between the diffusion coefficient D and the relaxation frequencies fseg and fion of the 3D-HION-APEs is investigated
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
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