1,721,464 research outputs found
The idea of political communication
No full textSIGLEAvailable from British Library Document Supply Centre- DSC:DX91268 / BLDSC - British Library Document Supply CentreGBUnited Kingdo
Autonomous oceanic primary production measurements through novel chlorophyll fluorometry
No full textPhytoplankton Primary Production (PP) is a key index of marine ecosystem function, setting the constraint on energy flux to the marine biosphere. Extreme under-sampling limits confidence in our best estimates of the magnitude, variability, and drivers of such variability in PP. The current work introduces, assesses, and demonstrates a new active chlorophyll fluorescence measurement sensor, developed by Chelsea Technologies Group (CTG), the STAFES (Single Turnover Active Fluorometry of Enclosed Samples). These sensors measure a range of primary production parameters, based on Electron Transport Rate (ETR), and contain 7 measurement LEDS, compared to 2 on earlier versions of single turnover active fluorometers. They are designed to operate continuously and autonomously making them Marine Autonomous System (MAS) deployable. Such deployments have the potential to greatly improve confidence and crucially, spatio-temporal scales of ETR derived parameters, and PP. As a precursor to in situ deployment, the residual error inherent in STAFES, post spectral correction was investigated over a range of assumed and measured phytoplankton absorption spectra. These analyses were performed using a series of hypothetical calculations using idealised underwater light fields generated with the HYDROLIGHT radiative transfer model, with calculations subsequently used to produce global scale residual error estimates. Overall residual errors in the upper water column (i.e. at or above the 50% light depth) remained modest even in the most productive regions where they were highest. Hence using a 7-wavelength instrument such as STAFES and then performing spectral corrections, results in the residual error already being reduced to a level where other sources of measurement error and uncertainties in algorithms will likely dominate. The STAFES sensor potential was demonstrated by performing a series of experiments in the South East (SE) Pacific sector of the Southern Ocean. Results provided new insight into the effects of iron (Fe) and light availability on the coupling between CO2 assimilation and photosynthetic electron transport in natural phytoplankton assemblages as quantified using the electron requirement for carbon fixation (Fe:C). Furthermore, Fe:C reduced by around 35-50% after the relief of Fe limitation, both within the light limited and saturated regions of the photosynthesis irradiance curve, expanding the overall range of such observed Fe driven variability. A first demonstration of autonomous capability was then achieved by deploying STAFES on the ALR MAS platform for four successful data gathering deployments at sea, which were validated by a range of additional sensors. The results represent the first known demonstration and analysis of spectrally resolved PEP (Photo Excitation Profile) variable fluorescence by wavelength (Fv (λ)) data using the variable fluorescence technique deployed on a fully autonomous platform. Finally, placing the results chapters in context within the final chapter allowed remaining key uncertainties to be highlighted. The current thesis thus presented a number of completely unique data sets with a new instrument / platform interface, while further highlighting future work which would be required in order to fully realise the potential of STAFES
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
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
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