1,724,868 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
Sea surface salinity and the ocean structure in the tropical Indian Ocean
No full textThe variability of the tropical Indian Ocean (TIO) is crucial to the global water cycle and heat transportation. At the seasonal time scale, the variability of the TIO is closely related to the monsoon circulation. Interannually, on the one hand, it is influenced remotely by the variability of the Pacific Ocean through atmospheric bridge and Rossby wave. On the other hand, the variability of TIO is independent of El Niño-Southern Oscillation (ENSO) and varies as a dipole pattern along the equator, known as the Indian Ocean dipole (IOD). In addition, the unique distribution of the TIO with shallower thermocline in the west, due to the unstable easterlies along the equator, makes the variability of the TIO differ from that in the Pacific and the Atlantic Ocean with deeper thermocline in the west. However, the TIO variability is still hard to precisely predict and the difficulty is well acknowledged nowadays.
To this end, the main aim of this dissertation is to better understand the seasonal and interannual variability of the TIO. Specifically, the first objective is to distinguish the relative impacts of heat flux and wind stress on the interannual variability of upper-ocean temperature in the TIO. The second objective focuses on studying the relationships among the parameters in the mixed layer and thermocline with the barrier layer thickness (BLT) in the TIO. The last objective of this dissertation is to investigate the role of sea surface salinity (SSS) in the onset of South Asian Summer Monsoon (SASM). To achieve this aim, the observation datasets including float and satellite data, reanalysis data, and simulations from a high-resolution model, are employed.
In Chapter 2, we compared the ocean general circulation model (OGCM) hindcast with the reanalysis and observation data and found that they were consistent in the simulation of the climatological mean and interannual variability of the upper-ocean temperature vertical structure in the TIO. Therefore, OGCM was adopted in this study to study the variability of the TIO. Two sensitivity simulations were designed to study the relative contribution of heat flux and wind stress to the variability of TIO: one was set with only heat flux varying interannually, and another one assumed only wind stress varying interannually. The results show that the impacts of heat flux and wind stress on the interannual variability of ocean temperature in the TIO have a depth-dependent feature. Specifically, heat flux mainly dominates the interannual variability of ocean temperature above the depth of approximately 30 m in the TIO, while wind stress contributes most to the interannual variability of ocean temperature below the depth of 30 m. This depth-dependent feature has also been observed for sub-areas and different seasons in the TIO. Therefore, we define the depth where the dominant force switches from heat flux to wind stress in the TIO as the “crossing depth”. Shallower crossing depth indicates that heat flux only controls the interannual variability of ocean temperature near the surface while wind stress is the dominant driving force for the interannual temperature variability in the upper-ocean, such as the Seychelles-Chagos Thermocline Ridge (SCTR) and the eastern part of the Indian Ocean Dipole (IODE).
In chapter 3, we assessed the driving forces for the variability of the barrier layer thickness (BLT) in TIO. The barrier layer is defined as a thinner layer between the bottom of the mixed layer and the top of the thermocline. The BLT in the TIO has significant seasonal and interannual variabilities. The results of this study show that the sea surface temperature (SST) barely contributes to the variability of BLT but the main forcing on the BLT from the mixed layer can be explained by the variability of SSS. At the seasonal time scale, the dominating drivers of the BLT variability are different in the western and eastern TIO. In the western TIO, SSS exerts a negative correlation with the BLT variability during boreal autumn, winter, and spring while shows minimal impacts on the BLT variability in summer. In the eastern TIO, the thermocline is the dominant driver for the BLT variability, and it has positive correlations with BLT in all four seasons. At the interannual time scale, the variability of BLT in the TIO is affected by the IOD and ENSO events. Particularly, in the eastern TIO, thinner BLT could be detected mainly induced by the anomalous thermocline during the positive IOD and El Niño years. In the western TIO, deepening thermocline due to El Niño induced anomalous wind stress results in thicker BLT. But the correlation between BLT and El Niño does not become weaker with the weakening relationship between thermocline and El Niño. This is because of the variation of SSS.
In Chapter 4, we investigated the role of sea surface salinity anomalies (SSSAs) in the onset of the SASM. Positive SSSAs appears in the western TIO before the onset of SASM. This SSSAs has two maxima in the symmetry of the equator with one in the southern TIO and another one in the northern TIO. The location of the southern maxima corresponds to the SCTR. It is found that the SSSAs respond more sensitively to the change of the atmospheric circulation than sea surface temperature anomalies (SSTAs). The positive SSSAs in the SCTR, induced by the anomalous wind stress curl and associated with thinner BLT anomalies, provides a favorable environment for the decreasing SSTAs during spring. Meanwhile, this SSSAs-BLT-SSTAs process also develops in the SSSAs maxima of the northern TIO but happens later than that in the southern TIO. Therefore, this time-lag between the northern and southern TIO strengthened the north-to-south SST gradient, which in turn, promotes the northward crossing current for the onset of SASM.
To conclude, this Ph.D. research primarily investigates the variability of the TIO by distinguishing the main driver of the interannual upper-ocean temperature variability, studying the relationships between SSS and thermocline with BLT at seasonal and interannual scales and discovering the role of SSS in the onset of SASM. However, more efforts are highly demanded in the near future to investigate more sophisticated air-sea interaction mechanism within the TIO. For example, the theory of crossing depth is only adapted in the area of (15°S-20°N). Thus, how to distinguish the relative impacts of heat flux and wind stress on the upper-ocean variability in the area to the south of 15°S is still to be unraveled. In addition, the role of SSS in the interannual variability of the TIO needs more precise datasets to investigate and the numerical modeling with more sophisticated air-sea interactions should be taken into consideration
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
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