1,721,018 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
Part of the global seawater delta oxygen-18 database from reference Frew 1995
No full textPart of the global seawater delta oxygen-18 database from reference Frew 199
Tracing Nutrients and Contaminants in Nearshore Food Web
Get PDFSewage derived organic matter from domestic and municipal wastewater, promotes enhanced secondary productivity, eutrophication and trace metal contamination, reduction in oxygen levels, and biodiversity. It poses a potential impact on human health, contamination of seafood and water and ecological disturbances in the natural aquatic ecosystem. Thus, this research examined the impact of improvement in treatment and disposal schemes employed by a municipal sewage treatment facility on a previously sewage contaminated coastal marine system. It took a critical look into the influence of the discharged of inadequately treated sewage effluent and the modern improved mitigating efforts put in place to ensure proper treatment and disposal by the municipal wastewater treatment plant on the coastal marine waters. It also investigated the influence of other potential terrestrial organic nutrients and contaminants on the coastal marine waters, the flow of energy and their fate through the natural coastal marine food web. Stable isotope analyses incorporated with mixing models, other independent chemical tracers such as (i.e. faecal sterol, fatty acid and elemental analyses) were utilised to infer change in the sewage derived organic matter dynamics of the coastal marine waters. The detected change was attributed to the modification in wastewater treatment and disposal techniques adopted by the municipal wastewater treatment plant. The differences in the carbon and nitrogen isotope ratios of Mytilus galloprovincialis (sentinel organism) were assessed in a preliminary survey to determine the tissues of choice as indicative tools for long-term ecological-based study aimed at tracing the sources and fate of sewage organic materials in the coastal marine waters. The preliminary survey aided the experimental design of the study. Isotope mass balance mixing models were fitted to quantify the contributions of land-based organic materials as part of the diet constituents to examine the influence of terrigenous materials on observed diet switching changes from sewage-derived nutrient source to marine nutrient source in Mytilus galloprovincialis, a prevalent resident marine bivalve collected at the nearshore marine waters. Biochemical compositions and elemental concentrations (independent tracers) in Mytilus galloprovincialis were analysed and used as independent indicative tools for testing the assumptions obtained from the stable isotope analysis mixing models. The tracers indicated the source of nourishment to the resident organism and provided additional insight into the organic nutrient supply and contaminant dynamics of the coastal marine waters. The independent tracers revealed that the marine particulate organic matter was main source of nourishment to the marine bivalve. The sea lion colony provided a minor contribution of faecal matter to the nearshore marine waters. The chemical tracers affirmed that the improvement in the treatment and disposal methods had a positive impact on the nearshore marine waters. Trace metal levels and human health risk assessment on the nearshore marine bivalve affirmed the safe human consumption of the nearshore marine fisheries
Assessing the Cadmium Paleo-nutrient Proxy
No full textOceanographic studies in the last three decades have provided insights on the correlation between cadmium (Cd) and phosphate (PO43-) in seawater. That the concentrations of these two are closely related in open ocean waters was first observed in mid-1970s (Boyle, 1976; Martin et al., 1976). The seeming consistency of this relationship has been exploited to provide a proxy for historic PO43- based on measurements of Cd in fossil material. However, at present, there is no single generally acceptable explanation for the Cd-PO43- relationship particularly in certain areas of the surface ocean and the use of Cd as a paleo-nutrient proxy in the surface ocean is therefore controversial. Experimental work described in this thesis investigates the Cd–PO43- relationship in two study systems with distinct physicochemical and biological properties (Subantarctic and Subtropical waters, east of New Zealand). This study involves field measurement of dissolved and particulate concentrations of some bioactive trace metals (Cd, Fe, Zn, Co), nutrients (PO43, NO3-, Si(OH)4) and biological indicators (chlorophyll a, particulate organic carbon and particulate organic nitrogen) as well as a laboratory culture study of Cd uptake in the diatom Nitzschia sp. (Clone AI).
A pragmatic investigation of the factors responsible for seasonal variation in the Cd and PO43- relationship along with other relevant oceanographic parameters off the southeast coast of New Zealand has been conducted. Strong seasonality was seen in the biological parameters and also in the trace element concentrations. The correlation of the trends in Cd concentrations and the Cd/PO43- ratios with indicators of biological activity (chlorophyll a, POC/PON and micronutrients) in this study indicate that the seasonal variation in Cd/PO43- ratios observed in these waters is due to biological activities. The drawdown in dissolved Cd concentration corresponded well with the drawdown in micronutrients and particulate Cd concentration was higher during algae growth as Cd partitioned from dissolved into the particulate phase at this time. From the timing of the changes in these parameters it is postulated that the mechanism of seasonal drawdown in dissolved Cd (and evolution of the Cd/PO43-) in Subantarctic Surface Water (SA) is a seasonal supply of Si(OH)4 into a Zn-depleted water in which certain species of phytoplankton are able to used Cd as a substitute for Zn. This results in microplankton (diatoms) dominating the phytoplankton assemblage in the late spring and coinciding with an intense drawdown in DCd (15 fold) and Si(OH)4. Underlying factors (during the algal growth season) such as Si(OH)4 (and Fe) supply, low dissolved Zn concentration and changes in the composition of phytoplankton community are factors modulating the Cd/PO43- ratio in the SA east of New Zealand.
Cd partitioned from dissolved to particulate phase due to biological uptake during a natural spring bloom event in an anticyclonic eddy off the east coast of North Island, New Zealand. Cd/PO43- ratios also decreased in the surface water as the bloom progressed. Mixed layer depth, biomass production and phytoplankton distribution were the contributing factors to the modulation of Cd/PO43- ratios observed in this bloom event. Results also show Cd uptake is not limited to diatoms as there was significant increase in particulate Cd during the nano-flagellates dominated period (phase 2). This is comparable to the observation in the Otago transect (Chapter 3) where Cd partitioned into different size fractions.
Higher Cd uptake and partitioning were observed in the diatom cultures (Nitzchia sp) with lower dissolved Zn concentrations in agreement with previous studies. However, Fe and Zn addition did not significantly increase the growth rate and biomass production in this organism.
Seasonal dependency of Cd/PO43- ratios on Cd uptake as shown in this thesis indicates that the Cd proxy is probably not reliable to reconstruct PO43- concentration in the past Southern Ocean
Tracing Nutrients and Contaminants in Nearshore Food Web
No full textSewage derived organic matter from domestic and municipal wastewater, promotes enhanced secondary productivity, eutrophication and trace metal contamination, reduction in oxygen levels, and biodiversity. It poses a potential impact on human health, contamination of seafood and water and ecological disturbances in the natural aquatic ecosystem. Thus, this research examined the impact of improvement in treatment and disposal schemes employed by a municipal sewage treatment facility on a previously sewage contaminated coastal marine system. It took a critical look into the influence of the discharged of inadequately treated sewage effluent and the modern improved mitigating efforts put in place to ensure proper treatment and disposal by the municipal wastewater treatment plant on the coastal marine waters. It also investigated the influence of other potential terrestrial organic nutrients and contaminants on the coastal marine waters, the flow of energy and their fate through the natural coastal marine food web. Stable isotope analyses incorporated with mixing models, other independent chemical tracers such as (i.e. faecal sterol, fatty acid and elemental analyses) were utilised to infer change in the sewage derived organic matter dynamics of the coastal marine waters. The detected change was attributed to the modification in wastewater treatment and disposal techniques adopted by the municipal wastewater treatment plant. The differences in the carbon and nitrogen isotope ratios of Mytilus galloprovincialis (sentinel organism) were assessed in a preliminary survey to determine the tissues of choice as indicative tools for long-term ecological-based study aimed at tracing the sources and fate of sewage organic materials in the coastal marine waters. The preliminary survey aided the experimental design of the study. Isotope mass balance mixing models were fitted to quantify the contributions of land-based organic materials as part of the diet constituents to examine the influence of terrigenous materials on observed diet switching changes from sewage-derived nutrient source to marine nutrient source in Mytilus galloprovincialis, a prevalent resident marine bivalve collected at the nearshore marine waters. Biochemical compositions and elemental concentrations (independent tracers) in Mytilus galloprovincialis were analysed and used as independent indicative tools for testing the assumptions obtained from the stable isotope analysis mixing models. The tracers indicated the source of nourishment to the resident organism and provided additional insight into the organic nutrient supply and contaminant dynamics of the coastal marine waters. The independent tracers revealed that the marine particulate organic matter was main source of nourishment to the marine bivalve. The sea lion colony provided a minor contribution of faecal matter to the nearshore marine waters. The chemical tracers affirmed that the improvement in the treatment and disposal methods had a positive impact on the nearshore marine waters. Trace metal levels and human health risk assessment on the nearshore marine bivalve affirmed the safe human consumption of the nearshore marine fisheries
Determining the Geographical Origin of Cocoa Beans in Chocolate using Stable Isotope Ratios
No full textSustainability of cocoa bean farms is becoming an increasingly important matter. With more chocolate showing more sustainability labels, there needs to be confidence in the consumer's mind on these labels. One way in which to build this confidence is to ensure traceability of the cocoa bean from farm to the final chocolate product.
The stable isotope ratio of cocoa bean samples were measured using IRMS to see if their isotope ratio profile reflects their country of origin. δ2H, δ13C and δ15N were all measured on the bulk unshelled cocoa bean, along with δ2H and δ13C of the three most abundant fatty acids within cocoa beans; Palmitic acid, Stearic acid and Oleic acid. The results were analysed using PCA and showed that the samples tended to split into two groups. Nicaragua, Ghana and Vietnam and Papua New Guinea, The Solomon Islands and Samoa.
Two chocolate samples were made from cocoa beans which originated from Ghana. The δ13C and δ2H of extracted fatty acids were analysed as their methyl esters (FAMEs) and compared to the results of the cocoa bean fatty acids. These results showed that the chocolate samples had isotope ratio values closer to that of Vietnam than Ghana. However, the samples from Ghana were also found to be close to those of Vietnam. As an investigative study, this study showed that the method of FAME isotope ratios could potentially be used in future to determine origin of cocoa beans. With some more samples and research, this could lead to the possibility of using it on cocoa beans within a mixture to determine origin.
This study also investigated the gas chromatography stable isotope analysis of underivatized fatty acids extracted from cocoa beans samples. This method is a way to analyse the fatty acids without the need to conduct mass balance calculations needed for FAME analysis. Although the chromatographic responses were found to be much lower than that of the FAME, results seen from one chromatographic peak showed similar trends observed for the δ13C in bulk and FAME analyses. Thereby indicating the potential for this technique to be in traceability studies
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
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