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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
Computational evaluation of comprehensive properties of MgX3H8 (X=Sc, Ti and Zr) compounds as effective solid-state hydrogen storage materials
Full text linkBu çalışmada, MgX3H8 (X=Sc, Ti, Zr) bileşiklerinin yapısal, mekanik, elektronik, dinamik, termodinamik ve hidrojen depolama özellikleri yoğunluk fonksiyonel teorisi (DFT) kullanılarak incelenmiştir. Daha önce bu bileşiklerin deneysel ya da teorik olarak çalışılmamış olması bu çalışmayı özgün kılmaktadır. Bu malzemeler, katı hal hidrojen depolama için potansiyel olarak umut verici hidrojen depolama malzemeler olarak değerlendirilmiştir. MgX3H8 (X=Sc, Ti, Zr) bileşiklerinin hesaplanan oluşum entalpileri, elastik sabitler ve fonon dağılım grafikleri, bu bileşiklerin termodinamik, mekanik ve dinamik olarak kararlı ve sentezlenebilir olduğunu ortaya koymuştur. B/G oranı, Cp ve Poisson oranı analizleri, MgSc3H8'in gevrek bir malzeme olduğunu, MgTi3H8 ve MgZr3H8'in ise sünek malzemeler olduğunu göstermiştir. Ayrıca, malzemelerin anizotropi faktörü, işlenebilirlik indeksi, sertlik, eime ve Debye sıcaklıkları da detaylı analiz edilmiştir. MgX3H8 (X=Sc, Ti, Zr) bileşiklerinin elektronik bant yapıları incelenmiştir. Bantların (valans ve iletim bantları) ana simetri doğrultuları boyunca Fermi seviyesini kesmesi nedeniyle metalik karakter sergilemiştir. Fonon dağılım eğrileri ve malzemelerin kısmi durum yoğunlukları pozitif frekanslara sahip olup, malzemelerin kübik yapıda dinamik olarak kararlı olduğunu göstermiştir. Gravimetrik hidrojen yoğunlukları MgSc3H8 için % 4.60 (w/w) MgTi3H8 için % 4.38 (w/w) ve MgZr3H8 için % 2.56 (w/w) olarak hesaplanmıştır. Hidrojen desorpsiyon sıcaklıkları MgSc3H8 için 239.54 K, MgTi3H8 için 241.76 K ve MgZr3H8 için 303.87 K olarak bulunmuştur. Malzemelerin mekanik özellikleri, hidrojen depolama için umut verici malzemeler olabileceklerini öne sürmektedir.In this study, the structural, mechanical, electronic, dynamic, thermodynamic, and hydrogen storage properties of MgX?H? compounds (X = Sc, Ti, Zr) were systematically investigated using density functional theory (DFT). To the best of our knowledge, these compounds have not been previously reported in either experimental or theoretical literature. This work represents the first comprehensive investigation of the various physical and chemical characteristics of these materials. They were considered promising candidates for solid-state hydrogen storage applications. The calculated formation enthalpies, elastic constants, and phonon dispersion relations confirmed that MgX?H? (X = Sc, Ti, Zr) compounds are thermodynamically, mechanically, and dynamically stable, indicating their potential synthesizability. Analysis of the bulk-to-shear modulus ratio (B/G), specific heat capacity at constant pressure (Cp), and Poisson's ratio revealed that MgSc?H? exhibits brittle behavior, whereas MgTi?H? and MgZr?H? are ductile in nature. Additionally, key parameters such as hardness, melting temperature, Debye temperature, machinability index, and elastic anisotropy factor were calculated and thoroughly analyzed. Electronic band structure calculations indicated a metallic character for all three compounds, as the valence and conduction bands intersect the Fermi level along high-symmetry directions. The dynamic stability of the cubic phase was further supported by the phonon dispersion curves and partial density of states, both of which exhibited only positive frequencies. The gravimetric hydrogen storage capacities were estimated to be 4.60 wt.% for MgSc?H?, 4.38 wt.% for MgTi?H?, and 2.56 wt.% for MgZr?H?, with corresponding hydrogen desorption temperatures of 239.54 K, 241.76 K, and 303.87 K, respectively. These mechanical and hydrogen storage characteristics suggest that the investigated MgX?H? compounds are promising candidates for use as host materials in solid-state hydrogen storage systems
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
Computational evaluation of comprehensive properties of MgX3H8 (X=Sc, Ti and Zr) compounds as effective solid-state hydrogen storage materials
No full textBu çalışmada, MgX3H8 (X=Sc, Ti, Zr) bileşiklerinin yapısal, mekanik, elektronik, dinamik, termodinamik ve hidrojen depolama özellikleri yoğunluk fonksiyonel teorisi (DFT) kullanılarak incelenmiştir. Daha önce bu bileşiklerin deneysel ya da teorik olarak çalışılmamış olması bu çalışmayı özgün kılmaktadır. Bu malzemeler, katı hal hidrojen depolama için potansiyel olarak umut verici hidrojen depolama malzemeler olarak değerlendirilmiştir. MgX3H8 (X=Sc, Ti, Zr) bileşiklerinin hesaplanan oluşum entalpileri, elastik sabitler ve fonon dağılım grafikleri, bu bileşiklerin termodinamik, mekanik ve dinamik olarak kararlı ve sentezlenebilir olduğunu ortaya koymuştur. B/G oranı, Cp ve Poisson oranı analizleri, MgSc3H8'in gevrek bir malzeme olduğunu, MgTi3H8 ve MgZr3H8'in ise sünek malzemeler olduğunu göstermiştir. Ayrıca, malzemelerin anizotropi faktörü, işlenebilirlik indeksi, sertlik, eime ve Debye sıcaklıkları da detaylı analiz edilmiştir. MgX3H8 (X=Sc, Ti, Zr) bileşiklerinin elektronik bant yapıları incelenmiştir. Bantların (valans ve iletim bantları) ana simetri doğrultuları boyunca Fermi seviyesini kesmesi nedeniyle metalik karakter sergilemiştir. Fonon dağılım eğrileri ve malzemelerin kısmi durum yoğunlukları pozitif frekanslara sahip olup, malzemelerin kübik yapıda dinamik olarak kararlı olduğunu göstermiştir. Gravimetrik hidrojen yoğunlukları MgSc3H8 için % 4.60 (w/w) MgTi3H8 için % 4.38 (w/w) ve MgZr3H8 için % 2.56 (w/w) olarak hesaplanmıştır. Hidrojen desorpsiyon sıcaklıkları MgSc3H8 için 239.54 K, MgTi3H8 için 241.76 K ve MgZr3H8 için 303.87 K olarak bulunmuştur. Malzemelerin mekanik özellikleri, hidrojen depolama için umut verici malzemeler olabileceklerini öne sürmektedir.In this study, the structural, mechanical, electronic, dynamic, thermodynamic, and hydrogen storage properties of MgX?H? compounds (X = Sc, Ti, Zr) were systematically investigated using density functional theory (DFT). To the best of our knowledge, these compounds have not been previously reported in either experimental or theoretical literature. This work represents the first comprehensive investigation of the various physical and chemical characteristics of these materials. They were considered promising candidates for solid-state hydrogen storage applications. The calculated formation enthalpies, elastic constants, and phonon dispersion relations confirmed that MgX?H? (X = Sc, Ti, Zr) compounds are thermodynamically, mechanically, and dynamically stable, indicating their potential synthesizability. Analysis of the bulk-to-shear modulus ratio (B/G), specific heat capacity at constant pressure (Cp), and Poisson's ratio revealed that MgSc?H? exhibits brittle behavior, whereas MgTi?H? and MgZr?H? are ductile in nature. Additionally, key parameters such as hardness, melting temperature, Debye temperature, machinability index, and elastic anisotropy factor were calculated and thoroughly analyzed. Electronic band structure calculations indicated a metallic character for all three compounds, as the valence and conduction bands intersect the Fermi level along high-symmetry directions. The dynamic stability of the cubic phase was further supported by the phonon dispersion curves and partial density of states, both of which exhibited only positive frequencies. The gravimetric hydrogen storage capacities were estimated to be 4.60 wt.% for MgSc?H?, 4.38 wt.% for MgTi?H?, and 2.56 wt.% for MgZr?H?, with corresponding hydrogen desorption temperatures of 239.54 K, 241.76 K, and 303.87 K, respectively. These mechanical and hydrogen storage characteristics suggest that the investigated MgX?H? compounds are promising candidates for use as host materials in solid-state hydrogen storage systems
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
Phase transitions, elastic and electronic properties of hydrogen storage Na2PdH4
No full textHydrogen can be absorbed by some materials at specific pressures and temperatures. This is extremely important in terms of creating carbon-free and sustainable society. In this work hydrides are good candidates to fulfill these aims. Electronic and magnetic properties of hydrides are investigated. This study considers Na2PdH4 as solid storage of hydrogen material. Hydrogen is highly soluble in palladium and can be stored in large amounts at ambient conditions. The structural evolution, electronic and elastic properties of Na2PdH4 has been investigated by means of density functional theory. The SIESTA software package is used with the generalized gradient approximation for the exchange-correlation functional and norm-conserving Troullier-Martins pseudopotentials. High-pressure computations have been carried out to reveal phase transitions. Na2PdH4 is transformed from I4/mmm tetragonal structure to Immm orthorhombic structure at 100 GPa. The electronic band structures and density of states are obtained for both phases. Mechanical stability is analyzed using the elastic constants. Moreover, several parameters such as Young's modulus, shear modulus, and their ratios are obtained and discussed. © 2021 Author(s)
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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