1,720,967 research outputs found
Stable Isotopic Profiling of New Zealand Milk Powder
No full textTo contact the author please email: [email protected] thesis aims to develop a method to investigate the ability of bulk stable isotope and compound specific stable isotope tools to verify whether dietary feed fatty acids, bovine milk water and major bovine milk fatty acids are conveying biogeochemical attribution of their production region. This technique opens new insights into milk regional authenticity identification.
A multiple linear regression (MLR) model based on New Zealand climatic parameters was employed to verify its ability to predict δ2H values of rainfall from milk production regions. The MLR model showed promise to predict δ2H values of regional rain, yielding a high correlation to actual rain δ2H values (R2 = 0.73, P<0.05). Subsequently the model’s generated estimates of δ2H values for precipitation of the milk production regions, revealed strong geographical correlation between bulk δ2H values and δ2H values of some bovine milk short chain fatty acids (SCFA) to long chain fatty acid (LCFA).
In order to understand which of the major fatty acids in milk powder have the potential discrimination capability to allow the provenancing of milk powder, the δ2H value of C4:0 (butyric), C14:0 (myristic), C16:0 (palmitic) and the δ2H value of bulk milk which showed the highest correlation to regional rainfall was selected and analysed by employing multivariate statistics. The δ2H values of these compounds were found to be capable of explaining 91% of the isotopic variation. The hydrogen isotopic compositions of these milk compounds were able to separate milk production regions across New Zealand.
Subsequent exploration into finding the isotopic link between farm drinking water, grass/feed and milk, revealed that bovine milk bulk and fatty acid hydrogen isotope composition carries isotopic attributions both from feed and local water. However the influence of regional water on the 2H composition of the milk seems to be more pronounced.
The influence of seasonal variability on milk was examined on milk powder samples sourced from Norway. Results indicate that the milk powder fatty acid δ2H values and fatty acid concentrations were influenced by the time of sampling throughout the year, while the bulk milk δ2H and δ13C values remained relatively consistent across the sampling period. This may suggest a presence of a region specific isotope variability that may further be explored by comparing it with variability patterns of other regions.
A preliminary assessment on the potential of δ2H from milk fatty acids and bulk milk for determination of an adulterant (an unknown milk powder) in milk powder was investigated. Multivariate statistics were used to quantify the level of adulteration, which was able to resolve differences at a 5% level of adulterant in an authentic sample.
This thesis explores the potential application of stable isotope analysis to the authentication of the provenance of New Zealand milk. The approach utilized in this study could be adopted in other milk producing regions, or applied to other milk products such as infant formula for authentication purposes
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
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
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
Stable isotope analysis of amino acids: A tool to understand trophic relationships in terrestrial and marine food webs
No full textAnalytical methodologies have been developed for the compound-specific isotope analysis of amino acids (CSIA-AA). Amino acids are the molecules of choice as they are the building blocks of proteins and ultimately, the building blocks of life. The isotopic signature can also be manipulated to generate patterns, calculate trophic levels and provide other tools to further understanding of C and N origins and flows from their source and through the food web.
Although many recent studies have been developing, using and expanding the AA method, there are still a lot of possible applications of the method to be explored. In the present study, the AA method was tested in multiple challenging scenarios with samples of different matrices, different sizes and from different ecosystems.
At the edge between marine-terrestrial environments, the AA method was applied to unravel the trophic relationship that links a scarab larva and mites. Suspected to be parasitic, the interpretation of C and N isotopic signature in AAs (δ13CAA and δ15NAA respectively) and associated patterns revealed that the scarab larva - mite trophic relationship was instead commensalistic. Similar δ13CAA indicated the affiliation to the same C3-plant based food web, the trophic level results clearly showed that the mite was two trophic levels higher than the larva, hence proving its none-parasitic behaviour; and finally, a shift in δ15NPhe baseline redirected the mite source of C and N to the larva’s faeces.
The AA method was then applied on suspended particulate organic matter (POM) from oligotrophic areas in the North and South Atlantic oceans, in order to identify the origins of C and N fuelling the base of the marine food web. δ13CAA patterns revealed the domination of autotrophic-sourced material in the North and South Atlantic ocean. Furthermore, while δ15NAA patterns indicated that the primary production in shallow waters of the studied area was dominated by prokaryotes in the North Atlantic Ocean, the total fractionation coefficient (εtot) pointed out the eukaryotic and prokaryotic origins of N across the 40 oS transect in the South Atlantic Ocean. This information was backed up by the depth variations observed in δ15NPhe values. Complementarily, the heterotrophic recycling parameter (ΣV) indicated that the main mechanism driving 15N enrichment of suspended POM in both oceans appeared to be the isotope fractionation associated with heterotrophic degradation; especially at depth below 100 m. Heterotrophic bacteria re-synthesis was more active in the South Atlantic Ocean. Furthermore, AAs role in oligotrophic ocean were investigated using an analytical methodology developed specially to measure dissolved free amino acids (DFAA) concentrations in seawater.
The results of all research confirmed in polyvalent use of the AA method and encourage future research to use it as a reliable tool for understanding the N-cycle in oligotrophic open oceans
Stable isotope analysis of amino acids: A tool to understand trophic relationships in terrestrial and marine food webs
No full textAnalytical methodologies have been developed for the compound-specific isotope analysis of amino acids (CSIA-AA). Amino acids are the molecules of choice as they are the building blocks of proteins and ultimately, the building blocks of life. The isotopic signature can also be manipulated to generate patterns, calculate trophic levels and provide other tools to further understanding of C and N origins and flows from their source and through the food web.
Although many recent studies have been developing, using and expanding the AA method, there are still a lot of possible applications of the method to be explored. In the present study, the AA method was tested in multiple challenging scenarios with samples of different matrices, different sizes and from different ecosystems.
At the edge between marine-terrestrial environments, the AA method was applied to unravel the trophic relationship that links a scarab larva and mites. Suspected to be parasitic, the interpretation of C and N isotopic signature in AAs (δ13CAA and δ15NAA respectively) and associated patterns revealed that the scarab larva - mite trophic relationship was instead commensalistic. Similar δ13CAA indicated the affiliation to the same C3-plant based food web, the trophic level results clearly showed that the mite was two trophic levels higher than the larva, hence proving its none-parasitic behaviour; and finally, a shift in δ15NPhe baseline redirected the mite source of C and N to the larva’s faeces.
The AA method was then applied on suspended particulate organic matter (POM) from oligotrophic areas in the North and South Atlantic oceans, in order to identify the origins of C and N fuelling the base of the marine food web. δ13CAA patterns revealed the domination of autotrophic-sourced material in the North and South Atlantic ocean. Furthermore, while δ15NAA patterns indicated that the primary production in shallow waters of the studied area was dominated by prokaryotes in the North Atlantic Ocean, the total fractionation coefficient (εtot) pointed out the eukaryotic and prokaryotic origins of N across the 40 oS transect in the South Atlantic Ocean. This information was backed up by the depth variations observed in δ15NPhe values. Complementarily, the heterotrophic recycling parameter (ΣV) indicated that the main mechanism driving 15N enrichment of suspended POM in both oceans appeared to be the isotope fractionation associated with heterotrophic degradation; especially at depth below 100 m. Heterotrophic bacteria re-synthesis was more active in the South Atlantic Ocean. Furthermore, AAs role in oligotrophic ocean were investigated using an analytical methodology developed specially to measure dissolved free amino acids (DFAA) concentrations in seawater.
The results of all research confirmed in polyvalent use of the AA method and encourage future research to use it as a reliable tool for understanding the N-cycle in oligotrophic open oceans
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