1,720,983 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
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
From atoms to landscapes through time: the chemical controls on carbonate precipitation and phosphate concentration in alkaline lakes
Full text linkAs some of the most biologically productive environments on the modern Earth, alkaline lakes may have figured prominently in the evolution of the global carbon cycle and in the chemical origins of life. Significant CaCO3 supersaturation is a ubiquitous trait of alkaline lakes, controlling the geochemical evolution of lake waters as well as the mineralogy and sedimentary expression of their deposits. By definition, CaCO3 supersaturation requires compounds that interfere or inhibit precipitation, yet the processes controlling CaCO3 saturation in many alkaline lakes are poorly understood. In the pursuit to understand the essential physicochemical processes influencing non-skeletal CaCO3 precipitation, this study focusses on the roles of aqueous phosphate and magnesium in influencing the dissolved carbonate system. It also dissects the roles of alkalinity and pH, addressing a comprehensive compilation of published water chemistry data of alkaline lakes from 16 countries in six continents, implementing a Pitzer ion interaction activity coefficient model to explore carbonate geochemistry and the potential role of these ions in maintaining CaCO3 supersaturation. This survey reveals that ∼80% of the investigated lakes are supersaturated with respect to calcite (0 14–45 and possibly within the range of 100–180. Nonetheless, it is pointed out in the present study that possible antagonistic effects of dissolved SiO2 and phosphate on carbonate precipitation and growth are presently not well constrained and should be investigated in future studies. Another relevant contribution of potentially wider implications for global budgets at the time of their formation is the maximum estimated volume of water implied in the deposition of these rocks, calculated to be in the order of 6 × 1019 L, ∼three orders of magnitude greater than the present volume of water in the Caspian Sea, the largest modern endorheic lake in the world. Finally, the picture emerging from the combination of theory, experimentation and geological investigation provided in this study establishes a robust framework for our understanding of the chemical controls on non-skeletal carbonate minerals deposited in sedimentary basins elsewhere. In turn, this extended knowledge may allow us to place better constraints on the chemical evolution of Earth’s surface conditions dating as far as the existing sedimentary carbonate rock record goes back in time
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
Exploring microbial mechanisms in arsenic adsorption and desorption in iron-manganese binary oxides
Full text linkArsenic (As) is a common trace metal in the environment and a global environmental concern due to its toxicity and occurrence in the groundwater of many countries in high concentrations. Understanding As adsorption and desorption mechanisms onto and from aquifer or soil minerals is important to comprehend As mobility and transport in aquatic environments. This thesis investigates As(V) adsorption and desorption dynamics onto and from iron-manganese (Fe-Mn) binary oxides formed through both biological and abiotic processes. Indeed, iron and manganese oxides often co-exist in the environment, and the roles of these binary phases in trace metal cycling are currently under-investigated. Fe-Mn binary oxides might play a significant role in As(V) adsorption dynamics in nature due to their high efficiency of As(V) adsorption. In our experiments, abiotically precipitated Fe-Mn binary oxides demonstrated higher adsorption capacity than ferrihydrite, an extensively studied potential As(V) adsorbent. Higher specific surface area and pore size might have contributed to the increased As(V) adsorption of Fe-Mn binary oxides. Both adsorption systems fitted greatly with the PseudoSecond-Order kinetic model, indicating adsorption of As(V) onto both minerals might have been caused by chemisorption. Though abiogenic forms of Fe- and Mn oxides have been investigated a lot previously, biogenic Fe-Mn binary oxides, which in nature may be formed through the activity of metal-oxidizing bacteria, are often overlooked in terms of their role in trace metals adsorption-desorption dynamics, including As(V). In this research, we also produced biogenic Fe-Mn binary oxides using Pseudomonas putida, which oxidized Mn(II) to Mn oxides, followed by the oxidation of Fe(II) to Fe oxides by the Mn oxides under microoxic conditions. Both phases were co-precipitated as finely inter-mixed biogenic Fe-Mn binary oxides. This synthesis procedure described a potential new pathway for biogenic Fe-Mn binary oxides formation at oxic-anoxic interfaces in nature. The synthesized biogenic minerals were characterized using a suite of analytical techniques, including X-ray Diffraction, Scanning Electron Microscopy, (Scanning) Transmission Electron Microscopy, Selected Area Electron Diffraction, Energy-Dispersive X-ray Spectroscopy (EDX), and fluorescence microscopy. The biogenic minerals appeared as aggregates of fine mineral particles and bacterial cells and EPS. Ultrathin plates, long chains, and globular morphologies were commonly observed in the biogenic Fe-Mn binary oxides minerals. Mineral particles were <100 nm in size, which categorized them as nanoparticles. Mineralogical analysis revealed that the minerals’ structures were amorphous or poorly crystalline and consisted of a mixture of birnessite and ferrihydrite nanocrystals. EDX analyses showed the heterogeneous distribution of Fe and Mn within the biogenic Fe-Mn binary oxides, confirming the existence of these elements in two distinct phases. These minerals contained a significant amount of phosphorus, which might have originated from the hydrolysis of the microbial cells and is thought to be present as phosphate ions bound to the mineral surfaces.
This research also compared the As(V) adsorption-desorption dynamics of biogenic and abiogenic Fe-Mn binary oxides and revealed the role of biofilm in adsorption-desorption mechanisms. Biogenic minerals demonstrated lower As(V) adsorption capacity as compared with abiogenic Fe-Mn binary oxides due to their close association with organic matter (bacterial cells and EPS), which might cover a significant portion of the mineral surfaces. Moreover, the presence of microbial cells and EPS (biofilm) could provide net negative charges at the surface of the biogenic minerals, which might cause electrostatic repulsion to the negatively charged As(V) species, impeding As(V) adsorption. Additionally, the presence of phosphate groups at the surface of the biogenic minerals might have blocked potential surface sites for As(V) adsorption. Adsorption of As(V) on biogenic minerals was found to be controlled by As(V) diffusion through biofilm, influencing As(V) adsorption onto the biogenic minerals. As(V) desorption experiments from both biogenic and abiogenic Fe- Mn binary oxides demonstrated that, while a small fraction of the adsorbed-As(V) might desorb, themajority of As(V) is adsorbed irreversibly on both types of minerals, presumably through chemisorption. This indicates that both minerals might be expected to retain As(V) even as the concentration of As(V) in solution changes, such as in the case of flood events and groundwater level change. This research sheds light on the potential formation pathway of biogenic Fe-Mn binary oxides at the oxic-anoxic interface of the water column in nature, highlighting their environmental importance. It also provides a better understanding of the As(V) adsorption and desorption onto and from both abiogenic and biogenic Fe-Mn binary oxides in the presence of microbial biofilms, which might have great environmental significance
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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