124,908 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
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
Long-period seismology on Europa: 2. Predicted seismic response
No full textPrevious studies have documented the potential for using relatively short-period body waves and intermediate-period surface waves to explore the structure and tectonics of Europa. We show that long-period measurements (0.001 to 0.1 Hz) may have large amplitudes of displacement (millimeters to centimeters) and are potentially measurable from orbit without requiring a lander. To accurately model the long-period response of Europa, we use normal modes calculated from physically self-consistent models of Europa's structure developed in part 1 (Cammarano et al., 2007). On the basis of the geometry of observed faults, we estimate that faulting events of magnitude 5 or larger may occur regularly. Synthetic seismograms show that long-period displacement measurements with millimeter accuracy could detect current tectonic activity and determine the thickness of Europa's ice shell, and confirm the presence of a subsurface ocean. Determination of deeper structure with seismic measurements, however, is more challenging in the presence of a global liquid ocean, which acts to decouple deeper seismic energy from the surface. Copyright 2006 by the American Geophysical Union
Long-period seismology on Europa: 1. Physically consistent interior models
No full textIn order to examine the potential of seismology to determine the interior structure and properties of Europa, it is essential to calculate seismic velocities and attenuation for the range of plausible interiors. We calculate a range of models for the physical structure of Europa, as constrained by the satellite's composition, mass, and moment of inertia. We assume a water-ice shell, a pyrolitic or a chondritic mantle, and a core composed of pure iron or iron plus 20 weight percent of sulfur. We consider two extreme mantle thermal states: hot and cold. Given a temperature and composition, we determine density, seismic velocities, and attenuation using thermodynamical models. While anelastic effects will be negligible in a cold mantle and the brittle part of the ice shell, strong dispersion and dissipation are expected in a hot convective mantle and the bulk of the ice shell. There is a strong relationship between different thermal structures and compositions. The "hot" mantle may maintain temperatures consistent with a liquid core made of iron plus light elements. For the "cold scenarios," the possibility of a solid iron core cannot be excluded, and it may even be favored. The depths of the ocean and core-mantle boundary are determined with high precision, 10 km and 40 km, respectively, once we assume a composition and thermal structure. Furthermore, the depth of the ocean is relatively insensitive (4 km) to the core composition used. Copyright 2006 by the American Geophysical Union
Pragmatic Case Studies as a Source of Unity in Applied Psychology
No full textTo unify or not to unify applied psychology: that is the question. In this article we review pendulum swings in the historical efforts to answer this question—from a comprehensive, positivist, “top-down,” deductive yes between the 1930s and the early 60s, to a postmodern no since then. A rationale and proposal for a limited, “bottom-up,” inductive yes in applied psychology is then presented, employing a case-based paradigm that integrates both positivist and postmodern themes and components. This paradigm is labeled “pragmatic psychology” and, its specific use of case studies, the “Pragmatic Case Study Method” (“PCS Method”). We call for the creation of peer-reviewed journal-databases of pragmatic case studies as a foundational source of unifying applied knowledge in our discipline. As one example, the potential of the PCS Method for unifying different angles of theoretical regard is illustrated in an area of applied psychology, psychotherapy, via the case of Mrs. B. The article then turns to the broader historical and epistemological arguments for the unifying nature of the PCS Method in both applied and basic psychology.Peer reviewe
Dr. Edwin Wright Collection: Author Unknown
Full text linkNotes - The author relates several short stories about his neighbours including Alex McDonell, homesteading and life around Meanook and Athabasca (1 page
Conductive carbon-nanotube/polymer composites: Spectroscopic monitoring of the exfoliation process in water and the crucial role of wetting
No full textA versatile, latex-based concept for efficiently dispersing Single Wall Carbon Nanotubes (SWNTs) in a highly viscous polystyrene matrix is described Crucial for the entire process is the ultrasound-driven exfoliation of the as produced SWNT bundles in water. The energy input must be sufficiently high to achieve the desired individualization, but at this stage sonication should be stopped to avoid damaging the SWNTs, which would reduce both electrical conductivity and strength. With UV/VIS spectroscopy the unraveling of the NT bundles can easily be monitored, a process which was simultaneously visualized with cryo-TEM and SEM images. These images were in agreement with the collected UV/VIS data. Depending on the molar mass distribution of the PS matrix, the well-dispersed SWNTs significantly raise the Tg of the PS. A low molar mass PS fraction, probably acting as a wetting agent for the SWNTs, seems to be required for an improved PS/SWNT interaction
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
Lithospheric Layering in the North American Craton from Anisotropic Full Waveform Inversion
No full textInternational audienceThe lithospheric thickness and layering within the lithosphere have been previously constrained under the north American craton from various seismic tomographic studies, SKS splitting data and receiver function analyses, revealing, in particular, the presence of at least one mid-lithospheric discontinuity (MLD) with strong topography, and large variations in lithospheric thickness, not always correlated with crustal age. Building upon previous work in our group (Marone and Romanowicz, 2007; Yuan and Romanowicz, 2010; Yuan et al., 2014, EPSL), we here we present the results of several improvements to the radial and azimuthal anisotropy inversion of long period waveforms jointly with SKS splitting data. We start from our latest radially anisotropic model NASEM5 (Clouzet et al, 2018, GJI) constructed using a combination of teleseismic and regional full waveform data down to 40s period, the spectral element method for wavefield computations, and the concept of "Box Tomography" (Masson and Romanowicz, 2017), in which teleseismic and regional waveforms are combined seamlessly through the introduction of time-reversal mirrors. We have now included inversion for azimuthal anisotropy using a combination of regional long period waveforms and SKS splitting data, taking advantage, in particular, of the dense sampling afforded by the TA deployment of USArray. We have also implemented a more efficient inversion for crustal structure. We here present an updated, higher resolution radially and azimuthally anisotropic model of the north American continent, with focus on its stable and cratonic parts, and discuss its salient features in the context of models for the construction and evolution of the continental lithosphere. We probe this model under several stations at which we have independently obtained finer scale layering using a Monte Carlo Markov Chain trans-dimensional inversion approach. In this approach, 1D layered models are constrained by combining Ps converted phase waveforms and the local depth profile from a radially anisotropic shear wave tomographic model (NASEM5), rather than surface wave dispersion, as often done. In this computationally efficient method, each trial layered model is first homogeneized (i.e. Capdeville and Marigo, 2008) before comparison with the local tomographic depth profile
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