1,720,971 research outputs found
Temperature Dependence Of Brillouin Light Scattering Spectra Of Acoustic Phonons In Silicon
Get PDFElectrons, optical phonons, and acoustic phonons are often driven out of local equilibrium in electronic devices or during laser-material interaction processes. The need for a better understanding of such non-equilibrium transport processes has motivated the development of Raman spectroscopy as a local temperature sensor of optical phonons and intermediate frequency acoustic phonons, whereas Brillouin light scattering (BLS) has recently been explored as a temperature sensor of low-frequency acoustic phonons. Here, we report the measured BLS spectra of silicon at different temperatures. The origins of the observed temperature dependence of the BLS peak position, linewidth, and intensity are examined in order to evaluate their potential use as temperature sensors for acoustic phonons. (C) 2015 AIP Publishing LLC.National Science Foundation (NSF) Thermal Transport Processes Program CBET-1336968PhysicsCenter for Complex Quantum SystemsMaterials Science and EngineeringTexas Materials InstituteMechanical Engineerin
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
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Control of spin waves using charge and heat flows
Get PDFThe manipulation and propagation of spin degree of freedom have been extensively studied for last decades, and the relevant field of research is named spintronics. There are two different ways via which spins transport. In metals, spin polarized electrons can carry spin current. In magnetic insulators, spins can propagate as a form of waves (spin waves) without a flow of electrons. This dissertation investigates the spin transport by spin waves using micro-Brillouin light scattering technique. Spin waves can be excited with an external microwave source and may travel throughout media. Such propagating spin waves may find its application in phase locked nano-oscillators or logic devices. A major obstacle to these applications is the short propagation length of spin waves in metallic magnetic layers due to fast damping. To control damping in a ferromagnetic/heavy metal bilayer structure, we utilized spin polarized current generated via the spin Hall effect in the heavy metal layer. Such spin polarized current then exerts a torque on the adjacent magnetic layer, enabling control of magnetization dynamics via electric control. In addition to the control of spin wave amplitude, the charge current can effectively control the spin precession resonance when the bilayer is deposited on an Al₂O₃ substrate. The current control of spin precession resonance originates from modification of the uniaxial magnetic anisotropy field, which changes symmetrically with respect to the current direction. This change in anisotropy field may enable control of magnetization in micro-fabricated structures using currents. Spin waves, or magnons as quanta of spin waves, can also be thermally excited. Similar to phonons, thermal magnons can make a considerable contribution to energy transport. The coupling and possible non-equilibrium between magnons and other energy carriers have been used to explain thermally driven spin transport phenomena. We demonstrate that magnons can be driven out of local equilibrium with the phonon bath in a magnetic insulator, Y₃Fe₅O₁₂ (yttrium iron garnet, YIG), when a large temperature gradient is generated on the scale of a few microns. This result contributes to the fundamental understanding of spin transport under a thermal gradientPhysic
Variations on the Author
Get PDF“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
Get PDFWe 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
Get PDFWe 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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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