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A well-posed integral equation formulation for three-dimensional rough surface scattering
No full textWe consider the problem of scattering of time-harmonic acoustic waves by an unbounded sound-soft rough surface. Recently, a Brakhage Werner type integral equation formulation of this problem has been proposed, based on an ansatz as a combined single- and double-layer potential, but replacing the usual fundamental solution of the Helmholtz equation with an appropriate half-space Green's function. Moreover, it has been shown in the three-dimensional case that this integral equation is uniquely solvable in the space L-2 (Gamma) when the scattering surface G does not differ too much from a plane. In this paper, we show that this integral equation is uniquely solvable with no restriction on the surface elevation or slope. Moreover, we construct explicit bounds on the inverse of the associated boundary integral operator, as a function of the wave number, the parameter coupling the single- and double-layer potentials, and the maximum surface slope. These bounds show that the norm of the inverse operator is bounded uniformly in the wave number, kappa, for kappa > 0, if the coupling parameter h is chosen proportional to the wave number. In the case when G is a plane, we show that the choice eta = kappa/2 is nearly optimal in terms of minimizing the condition number
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
Episodic crustal growth in the southern segment of the Trans-North China Orogen across the Archean-Proterozoic boundary
No full textThe Dengfeng and Taihua Complexes are well-exposed Neoarchean to Paleoproterozoic units in the southern segment of the Trans-North China Orogen (TNCO). Zircon U–Pb dating shows that the Dengfeng Complex records two episodes (2568±11 Ma and 2306±6 Ma) of tonalite–trondhjemite–granodiorite (TTG) magmatism. All of the TTG rocks are characterized by high SiO2 (66.7–75.4 wt%), Na2O (3.20–5.06 wt%) and relatively low MgO (0.40–1.78 wt%). The Late Neoarchean TTG gneisses have very low contents of HREE (YbN = 0.69–2.75) and Y (1.73–7.07 ppm), with moderate [La/Yb]N (24.1–53.8) and high Sr/Y (65.1–291.3) ratios. The Early Paleoproterozoic TTG gneisses have low contents of HREE (YbN = 2.93–6.37) and Y (6.7–11.0 ppm), with moderate [La/Yb]N (10.1–27.0) and Sr/Y (10.6–52.1) ratios. Both suites show pronounced negative Nb–Ta, P and Ti anomalies but positive Sr and Pb anomalies. The Late Neoarchean TTG gneisses all have similar bulk-rock Nd and zircon Hf model ages with mainly positive eNd(t), and are interpreted as resulting from the melting of dominantly juvenile thickened lower crust with residual garnet and amphibole.The Early Paleoproterozoic TTG gneisses have extremely variable eNd(t) (-6.23 to +4.23) and heterogeneous zircon eHf(t) (-3.3 to +3.1), which are also best interpreted as resulting from the partial melting of thickened lower crust with residual amphibole and garnet. The Taihua Complex in the Xiaoqinling area records three episodes of Early Paleoproterozoic TTG magmatism (2.48 Ga at Caotan, 2.31 Ga at Houjiacun and 2.16 Ga at Bayuan), younger than the Taihua Complex in the Lushan area (2.85–2.72 Ga). All rocks have relatively low contents of HREE (YbN = 1.03–8.32) and Y (2.84–24 ppm), with moderate [La/Yb]N (8.7–88.4) and Sr/Y (19.8–125.8) ratios, and show negative Ta–Nb and Ti anomalies and positive Sr and Pb anomalies. The Caotan gneisses at 2.48 Ga and the Houjiacun TTG gneisses at 2.31 Ga have low Mg# (0.14–0.45), low Cr (>42 ppm) and Ni contents (1–21 ppm), with variable but overall positive eNd(t) and eHf(t) values, and were derived from the partial melting of thickened lower crust with residual garnet and amphibole. The younger Bayuan TTG gneisses at 2.16 Ga have low SiO2 (57.11–64.89 wt%), high MgO (2.64–4.62 wt%), Cr (100–247 ppm) and Ni (32–80 ppm), with negative whole rock eNd(t) and zircon eHf(t) values, resulted from the partial melting of delaminated lower crust that interacted with peridotitic mantle.The geochronology of the Dengfeng Complex (in the Dengfeng area) and the Taihua Complex (in the Lushan, Xiong’er and Xiaoqinling areas) reveals at least four magmatic episodes in the southern segment of the TNCO from the Late Mesoarchean to Early Paleoproterozoic (2.85–2.72 Ga, 2.57–2.48 Ga, 2.34–2.30 Ga and 2.20–2.07 Ga). The rocks of the two early episodes are dominantly of juvenile compositions with mostly positive whole rock eNd(t) and zircon eHf(t) values, suggesting two episodes of crustal growth formed in a subduction tectonic setting. The magmatic rocks of the third episode consist of both the juvenile and pre-existing crustal materials with variable whole rock eNd(t) and zircon eHf(t) values, which were generated in a subduction zone during the initial assembly of the NCC within the Columbia supercontinent cycle. The final episode of magmatism lacks juvenile materials with whole rock eNd(t) and zircon eHf(t) values being consistently negative. These may have resulted from the orogenic collapse. The episodic continental growth recorded in the southern segment of the TNCO was caused by subduction and consequent orogeny, consistent with global supercontinent cycles within the Late Archean and Early Paleoproterozoic
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
Multiple sources for the origin of granites: Geochemical and Nd/Sr isotopic evidence from the Gudaoling granite and its mafic enclaves, northeast China
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