1,720,999 research outputs found
An Analysis of Biomass Burning Proxy Records: Aromatic Acids in the Eclipse Ice Core in Yukon, Canada
No full texthttps://rdc.reed.edu/v1/resources/7196ac28-12a9-4d25-a80d-308db2cc5708/thumb/128.jpgUnderstanding forest fire history is one part of understanding the current climate we are in and how we have influenced it. This thesis devotes its attention to using the aromatic acids, vanillic and para-hydroxybenzoic acid, found in the Eclipse ice core to understand fire history of the past 1000 years. These aromatic acids have been found to be products in the combustion of lignins from forest fires and long-range transport. Concentrations of these aromatic acids are found throughout the ice core confirming that they can be preserved on a millennial timescale. p-HBA was found to have consistent centennial variability from 1000 C.E. until 1600 C.E. VA did not show centennial variability, but three periodic trends were identified from 1000 C.E. to 1060 C.E., 1400 C.E. to 1530 C.E., and 1764 C.E. until 2001 C.E. Both p-HBA and VA had their highest concentrations from 1400 C.E. to 1500 C.E. Both aromatic acid concentrations were also elevated from 1000 C.E. until 1060 C.E., which coincides with the Medieval Warm Period. This thesis shows that using aromatic acids on a millennial scale analysis can prove to be useful as a forest fire proxy and be productive in understanding biomass burning history
Exploratory Analysis of a Holocene Sea Salt Ice Core Record from Skytrain Ice Rise, Antarctica
No full texthttps://rdc.reed.edu/v1/resources/277f2c38-209e-4944-89fb-706e0a4056f4/thumb/128.jpgPaleoclimatology can reveal an enormous amount of information regarding the Earth’s climate. An ice core recently recovered from Skytrain Ice Rise, located on the coast of the West Antarctic Ice Sheet, yielded sea salt data with previously unseen behavior—namely, a sharp and significant increase in the early Holocene in average salt concentrations and variability that could be indicative of Ronne ice shelf collapse. Published analyses of Skytrain ice core are limited because it was drilled as part of an ongoing project. In this thesis, preliminary analytics are conducted to better understand temporal trends in the Skytrain ice core salt records, which can reveal important paleoclimatological information.Mathematical analyses and data visualizations are utilized to provide statistical evidence of broader hypotheses. Although many past ice core studies rely on traditional time series, other approaches can be employed which can potentially reveal previously unforeseen relationships. Computational methods were used to quantify these values.Ultimately, the data revealed that there was a statistically significant difference in sea salt values before and after an identified short-term “ramp” event in the early Holocene. A comparison between sea salt and non-sea salt components supports the hypothesis of ice shelf collapse. Additionally, cross-comparison with ice core sodium data from the South Pole revealed that this behavior was local to the drill site region. These results can be used to improve future models and analysis of climatological behavior
Total Air Content Analysis of the Skytrain Ice Core
No full text<p>This is Matlab-based script calculates elevation histories for the Skytrain Ice Core site based on a combination of measured ice core total air content and ice temperature histories (at bubble close-off) derived from the Community Firn Model (Stevens et al.,2020). Additionally, sensitivity tests can be run to the various controls on total air content. </p><p>Stevens, C. M., Verjans, V., Lundin, J. M. D., Kahle, E. C., Horlings, A. N., Horlings, B. I., and Waddington, E. D.: The Community Firn Model (CFM) v1.0, Geosci. Model Dev., 13, 4355–4377, https://doi.org/10.5194/gmd-13-4355-2020, 2020.</p>
Ice core vanillic acid and para-hydroxybenzoic acid concentrations, Akademii Nauk, Severnaya Zemlya archipelago, Russia, 2013-2015
No full text
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
Sodium and calcium data from the full Skytrain Ice Rise ice core
No full textThis dataset consists of sodium (Na) and calcium (Ca) data for the full length of the ice core drilled in 2018-19 at Skytrain Ice Rise (79.7417°S 78.545°W), Antarctica. The data were from water sampled continuously from the melt stream of a continuous flow analysis system and are presented at 20 cm resolution where data exist. The analysis method was inductively coupled mass spectrometry using an Agilent 7700x ICP-MS attached to the melt stream
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
Total air content data for 5-10 ka bp from Skytrain Ice Rise ice core
No full textThis dataset consists of total air content (TAC) data from 326-416 m from the ice core drilled in 2018-19 at Skytrain Ice Rise (79.7417°S 78.545°W), Antarctica. The samples cover a period of approximately 5000-10000 years before present. Measurements were made on 10 cm long sections of core using a volumetric vacuum-extraction method built in house. No cut-bubble correction has been applied to these data
- …
