1,721,405 research outputs found
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
FLASH radiotherapy treatment planning and models for electron beams
No full text: The FLASH effect designates normal tissue sparing at ultra-high dose rate (UHDR, >40 Gy/s) compared to conventional dose rate (∼0.1 Gy/s) irradiation while maintaining tumour control and has the potential to improve the therapeutic ratio of radiotherapy (RT). UHDR high-energy electron (HEE, 4-20 MeV) beams are currently a mainstay for investigating the clinical potential of FLASH RT for superficial tumours. In the future very-high energy electron (VHEE, 50-250 MeV) UHDR beams may be used to treat deep-seated tumours. UHDR HEE treatment planning focused at its initial stage on accurate dosimetric modelling of converted and dedicated UHDR electron RT devices for the clinical transfer of FLASH RT. VHEE treatment planning demonstrated promising dosimetric performance compared to clinical photon RT techniques in silico and was used to evaluate and optimise the design of novel VHEE RT devices. Multiple metrics and models have been proposed for a quantitative description of the FLASH effect in treatment planning, but an improved experimental characterization and understanding of the FLASH effect is needed to allow for an accurate and validated modelling of the effect in treatment planning. The importance of treatment planning for electron FLASH RT will augment as the field moves forward to treat more complex clinical indications and target sites. In this review, TPS developments in HEE and VHEE are presented considering beam models, characteristics, and future FLASH applications
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
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
Transition and Rare-Earth metal oxides coatings: Surface characterization, Thermo-mechanical properties, and chemical reactivity
Full text linkThis thesis describes a number of scientific studies investigating different interesting properties of rare earth metal oxides desired in different applications via combined experimental measurements and accurate density functional theory (DFT) calculations. The electronic, structural, mechanical and thermodynamic properties of cubic lanthanide sesquioxides are first reported, with a particular focus on the most common dioxide in the lanthanide family, ceria (CeO2). This is followed an investigation into the effect of Hf and Zr dopants on the reduction energies of pure ceria. The reduction enthalpies of Ce1-xHfxO2 and Ce1-xZrxO2 and Ce1-2xHfxZrxO2 solid solutions are computed as a function of the reduction extent (x). Alloying with Hf and Zr is found to systematically reduce the energies required to remove oxygen atoms from bulk of ceria. The computed coefficients in the Born-Huang criterion infer a mechanical stability of all cubic lanthanide sesquioxides. Acquired electronic parameters encompass Bader’s atomic charges and Partial Density of States (PDOS).
An important part of the thesis focuses on the catalytic capacity of CeO2 in acting as a stand-alone environmental catalyst toward the decomposition of a series of chlorinated volatile organic compounds, namely chloroethene, chloroethane and chlorobenzene. Guided by recent experimental measurements, the pyrolytic and oxidative decomposition of selected chlorinated compounds have been modelled on the most stable ceria surface, CeO2 (111). Dissociative addition (surface-assisted fission of the C-Cl bond) and direct elimination pathways (departure of a stable hydrocarbon entity with the co-adsorption of H and Cl atoms on the surface) assume comparable importance. Fission of the C-Cl bond over oxygen vacancies systematically necessitates lower energy barriers in reference to perfect surfaces. We have illustrated that observed catalytic deactivation in the experiment is attributed to the profound stability of adsorbed hydrocarbon adduct. Decomposition of an adsorbed phenyl moiety proceeds via addition of oxygen molecules to partially reduced surfaces. A simplified kinetic model plots the temperature-conversion profiles for the three compounds against corresponding experimental profiles, where a reasonable agreement has been attained.
Surfaces of terbium dioxide (TbO2) possess an important catalytic feature in that they are capable of producing hydrogen by splitting water molecules. We have computed a large array of thermo-mechanical properties including heat capacities, bulk modules and thermal expansions of bulk TbO2 as a function of temperatures and pressures based on the quasi-harmonic approximation (QHA) approach. Our calculated lattice constant and band gap were in good agreement with analogous experimental findings. A surface truncated along the (111), terminated with O atoms and with oxygen vacant site (111): O+1Vo incurs a higher thermodynamic stability across all values of oxygen chemical potential. Nonetheless, in the vicinity of the lean-limit of chemical potential the surface terminated with Tb atoms (111): Tb becomes more stable. The implications of these geometries on OH-H fission reactions have been discussed.
Magnetron sputtered CeO2 films as optically transparent materials, deposited onto crystalline silicon substrates at various oxygen-argon mixture gas, have been intensively studied and characterized by correlating their structural and chemical bonding states. All the thin films exhibit a polycrystalline character with cubic fluorite – structure for cerium dioxide along (111), (200) and (222) orientations. The XPS survey scans of the CeOx coatings revealed that that Ce, O, C elements are present in all of the obtained spectra of the studied films. XPS analysis demonstrated that the atomic percentages of Ce and O atoms increase as oxygen-argon mixture increases. Two oxidation states of CeO2 and Ce2O3 are present in the films prepared at lower oxygen/argon flow ratios; whereas the films are completely oxidized into CeO2 as the oxygen/argon flow ratio increase. Reflectance data obtained from UV-Vis examinations were utilized to calculate the optical constants such as absorption coefficient (α), the real and imaginary parts of the dielectric function (ε1, ε2), the refractive index (n) and the extinction coefficient (k). Our analysis indicates that the CeO2 films display indirect optical band gaps residing in the range of 2.25 - 3.1 eV. We utilized DFT calculations to estimate optical constants of a CeO2 cluster at ground state. The computed electronic density of states (DOSs) of the optimized unit cell of CeO2 yields a band gap that agrees well with the corresponding experimental value. The measured and DFT-computed absorption coefficient (α) exhibit a similar trend with similar values in the wavelength range from 100 to 2500 nm. Overall, a satisfactory correlation between the theoretical and experimental findings is demonstrated.
Spinal oxides of CuxCo3-xO4 thin films as one of metal mixed oxide systems, synthesized by sol-gel method and annealed at various temperatures ranging from º200 to º500 with interval 100, are deeply studied and characterized by various structural and optical characterization techniques. XRD data indicates that as annealing progresses, all the coatings possess a crystalline phase of Cu0.56Co2.44O4 (ICSD 78-2175) with preferential orientation along (400) reflection plane. Optical analysis reveals that the solar selectivity of the studied films improves as the annealing progresses. Bader’s charge analysis calculated by DFT implemented in VASP code points out that the Cu and Co atoms in all the stoichiometries hold positive charges whereas the O atoms are linked with negative charges. Our model reveals a covalent character for Cu-Co bond in all the system and ionic characteristics for Cu-O and Co-O bonds.
Finally, the influence of the variation in the Hubbard parameter U on the activation and reaction energies on CeO2-catalyzed reactions is studied. This has been achieved by surveying the change in activation and reaction energies for reactions underpinning the partial and full hydrogenation of acetylene over the CeO2 (111) surface. A positive correlation between the U values and reaction and activation energies reported. It is suggested that kinetic modeling against experimental profiles of products could be used as an approach to optimize the U value
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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