1,721,003 research outputs found
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
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
Evaluation of X-band polarimetric radar estimates of drop size distributions from coincident S-band polarimetric estimates and measured raindrop spectra
No full textAbstract—Recent research has demonstrated the value of polarimetric
measurements for the correction of rain-path attenuation
at X-band radar frequency and the estimation of rain
parameters including drop-size distributions (DSD). The issue
this paper is concerned with is to what degree uncertainties in
attenuation correction can affect the estimation of DSD. Since
attenuation-correction uncertainty enhances with rain path, our
hypothesis is that DSD retrieval uncertainty at X-band may deteriorate
with range. In this paper, we evaluate the relative accuracy
of X-band DSD retrieval against DSD estimates fromS-band radar
observations and in situ disdrometer spectra. We present comparisons
of various techniques for estimating DSD model parameters
from attenuation-corrected X-band dual-polarization radar
data. Coincident X-band polarimetric-radar (XPOL) and S-band
polarimetric-radar dual-polarized radar measurements from the
International H2O Project experiment as well as coincident XPOL
(MP-X) measurements over disdrometer during a typhoon storm
case in Japan are used to assess the accuracy of the different DSD
retrieval algorithms applied to X-band radar measurements
Active and passive remote sensing of precipitating storms during CaPE. Part II: Intercomparison of precipitation retrievals from AMPR radiometer and CP-2 radar
No full textOne of the recent campaigns devoted to precipitation studies using both active and passive microwave remote sensing systems was the Convection and Precipitation/Electrification Experiment (CaPE), which took place in central Florida during the summer of 1991. During CaPE, the airborne Advanced Microwave Precipitation Radiometer (AMPR), having four channels at 10.7, 19.35, 37.1 and 85.5 GHz and the National Center for Atmospheric Research CP-2 multiparameter radar at S-band (3 GHz) and X-band (10 GHz) were operated simultaneously. In this paper, we compare estimated hydrometeor liquid/ice water contents and surface rainrates, both retrieved from the AMPR radiometer and CP-2 radar measurements, for a case study consisting of a heavy precipitating storm over land near Cape Canaveral on August 12, 1991. The multi-frequency radiometer-based retrieval scheme uses a cloud-precipitation dataset generated from a cloud model and extended by a physically-constrained Monte Carlo procedure, along with a discrete-ordinate radiative transfer model and a principal component statistical technique to help formulate non-linear regression equations for the sought-after hydrometeor quantities. By applying linear discriminant analysis, the algorithm is used to estimate column integrated liquid/ice water contents, as well as the vertical profiles of these quantities to within a specified accuracy. Rainfall rates are estimated either by non-linear regression or by a suitable fallout model. The analysis has confined itself to along-track nadir-looking AMPR measuremets to avoid complications with variable polarization mixing and geometric distortion for off-nadir observations. Considering the different model assumptions used in the two types of retrieval algorithms and the diverse geophysical information content within the two types of measurements, substantial agreement between the radar- and radiometer-derived retrievals has been achieved for the columnar liquid/ice water contents and rainrates
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
Active and passive remote sensing of precipitating storms during CaPE. Part I: Advanced Microwave Precipitation Radiometer and polarimetric radar measurements and models
No full textThe Advanced Microwave Precipitation Radiometer (AMPR), an across-track scanning, four-channel (10.7, 19.35, 37.1, 85.5 GHz) total-power radiometer system, was instrumented aboard a NASA ER-2 aircraft during the 1991 CaPE (Convection and Precipitation/Electrification) project in central Florida. At a 20 km flight altitude, the AMPR provides fine-scale microwave imagery of Earth surfaces and its atmosphere, and is well-suited for diverse hydrological applications. During overflights of precipitation, coincident ground-based radar measurements were taken with the NCAR CP-2 dual-frequency, dual-polarization radar system. After remapping the radar data into a format compatible with the AMPR scanning geometry, the radar-derived profiles of rain, melting, and frozen hydrometeors are compared against the AMPR equivalent blackbody brightness temperature (T B) imagery. Microwave radiative transfer modeling procedures incorporating the radar-derived hydrometeor profiles were used to simulated the multifrequency AMPR imagery over both land and ocean background ER-2 flights. Within storm cores over land, columnar ice water paths up to 20 kgm–2 gradually depressed the 85 GHzT B as low as 100 K. The presence of tall vertical reflectivity columns encompassing > 20 kgm–2 columnar ice water path often produced 37 GHzT BT B directly over the core. Over ocean, the 10 GHz channel provided the clearest correlation with the rainfall amounts, whereas the 19 GHz channel saturated near 260 K past 10–15 mm hr–1 rain rate as determined by radar. Scattering by ice and melting ice at 37 GHz producedT B ambiguities over both raining and clear-ocean regions. Sensitivity to the columnar mixed phase region via the intermediate frequencies (19 and 37 GHz) is demonstrated and explained with the radar-derivedT B modeling. By superimposing vertical profiles of cloud liquid water (which this radar cannot measure) upon the radarinferred hydrometeor structure, additional information on the location of the peak cloud water and its amount relative to the vertical ice structure can be noted, along with a possible inference of the dominant ice particle size within the upper storm core.
These results suggest that as the resolution of passive radiometric measurements approaches dimensions where the antenna beams become increasingly filled by the cloud, precipitation retrieval via multifrequencyT B input is well-suited to a vertical profiling-type algorithm. This is further examined in Part II of this manuscript, where the radarderived vertical hydrometeor profiles are used to test the applicability of a multispectral cloud model-based approach to passive microwave precipitation retrieval from space
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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