1,721,150 research outputs found
Lacustrine evidence of early-Holocene environmental change in Northern Iceland: a multiproxy palaeoecology and stable isotope study
No full textEarly Holocene warming in Iceland caused rapid glacial ice melt which led to exposed landscapes on which soils developed and floras quickly established. Our records from northern Iceland suggest temperatures were up to 2-2.5°C warmer than present throughout the first two millennia post deglaciation (~10,500 to 8,500) on a background of soil and catchment development before catchment conditions started to stabilise. The warming trend over this period was not uniform however, but punctuated by a series of relatively short lived climatic events. Specifically inwash events are suggested by the δ13Corganic, %TOC and C/N data around 9600 cal BP and 8250 cal BP and are correlated by two independent sites. There is also evidence from the δ18Ocarbonate and δ13Ccarbonate records which suggests that progressive evaporation of the lakes in the region occurred from ~8200 cal BP, the timing of which accords well with other isotopic records of drier conditions from around the North Atlantic
Investigating the potential of oxygen-isotope records from anthropogenic lakes as tracers of 20th century climate change
No full textHistorical climate change in southern England was investigated using ostracod oxygen-isotope (δ 18O) records from two anthropogenic lakes in Hampshire, southern England. A strong relationship is observed between δ 18O ostracod, δ 18O precipitation and δ 18O lake_water in the contemporary environment and therefore δ 18O ostracod from the sedimentary record of these systems has the potential to reflect past climate variability. The possibility of these sites to act as archives of climate change through δ 18O ostracod analysis is explored through the study of lake sediment cores that cover the period from the early 20th century onwards. Both lakes showed similar directionality of shifts in δ 18O ostracod over this period, suggesting common driving mechanisms. Comparing δ 18O ostracod timeseries to meteorological data is challenging in part because of the complexity with which climate parameters are recorded in the δ 18O lake_water and consequently within lacustrine carbonates. Our findings highlight the potential of sediments from anthropogenic lakes to act as archives of past climate and indicate they may be an important resource for generating climatic reconstructions across the medieval to instrumental period, which the sediments of many anthropogenic lakes cover. Such climate reconstructions would greatly improve our spatial and temporal understanding of climate variability where instrumental data are unavailable and other natural archives are scarce.</p
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
New insights on Late Quaternary Asian palaeomonsoon variability and the timing of the Last Glacial Maximum in southwestern China
No full textAw6.35 m core (06SD) was retrieved from Lake Shudu, Yunnan Province, China. The sediments spanningthe period w22.6e10.5 kcal. yr BP (6.35e1.44 m) were analysed using a combination of variablesincluding pollen, charcoal, particle size, magnetic susceptibility and loss-on-ignition. The resultingpalaeorecord provides a high-resolution reconstruction of Late Pleistocene to Early Holocene climaticand environmental changes in southwestern China. Our findings indicate that from c. 22.6 to 17.7 kcal. yrBP, vegetation assemblages were primarily aligned to sparse xerophytic grassland/tundra or cold-tolerantboreal Pinus forest, indicating that climatic conditions in southwestern China were cold and dry.However, from c. 17.7 to 17.4 kcal. yr BP, the Lake Shudu record is punctuated by marked environmentalchanges. These include the establishment of denser vegetation cover, a marked expansion of boreal Pinusforest and enhanced hydrological activity in the catchment over centennial timescales, perhaps suggestingthat stepwise variations in the Asian Monsoon were triggering fundamental environmentalchanges over sub-millennial timescales. Thereafter, the pollen record captures a period of environmentalinstability reflected in fluctuations across all of the variables, which persists until c. 17.1 kcal. yr BP. Afterc. 17.1 kcal. yr BP, the expansion of steppe vegetation cover and coldecool mixed forest consisting ofmesophilous vegetation such as Tsuga and Picea, thermophilous trees including Ulmus and deciduousQuercus inferred from the Lake Shudu pollen record point to the establishment of warmer, wetter andperhaps more seasonal conditions associated with a strengthening Asian Summer Monsoon during theshift from Pleistocene to Holocene climatic conditions
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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