1,720,997 research outputs found
Natural Resources Research Institute Technical Report
No full textTo quantify the environmental history of the southern basin of Lake of the Woods (Ontario,
Manitoba and Minnesota), seven core locations were selected for retrospective analyses. Primary
goals were to determine pre-European settlement conditions and track the timing and extent of
anthropogenic impacts and remediation. Sediments were dated using isotopic analyses and fossil
remains, in concord with other stratigraphic indicators (organic and inorganic materials,
sedimentation rates, other biological entities), were used to reconstruct the ~150-year history of
the lake. Diatom assemblages were assessed from sediment intervals and inferred trophic
conditions in the profiles were derived using a regional diatom-based model for Minnesota lakes.
Nutrient reconstructions indicated a period of cultural eutrophication throughout much of the 20th
century. Despite a known reduction in anthropogenic nutrient flux to the lake in recent decades,
there has been no apparent reversal in eutrophication in the pelagic system. Contemporary
observations indicate that blooms of blue-green algae are becoming a greater problem. It appears
that legacy nutrient recycling and other environmental drivers are maintaining the current
condition of pelagic nutrient enrichment. Sedimentary analyses also indicated that physical
changes to the lake resulting from warming may be contributing in small part to the recent
reorganization of algal assemblages.University of Minnesota Grant Number: 3005 10425 00017805Reavie, Euan D; Edlund, Mark B; Andresen, Norman A; Engstrom, Daniel R. (2015). Paleolimnology of the Lake of the Woods southern basin. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/187352
Paleolimnological Approaches to Biological Monitoring
No full textThis chapter describes the specific information that can be provided by paleolimnological approaches, explains how paleolimnological studies can be performed, and informs readers about the most up-to-date techniques. The number of new paleolimnological studies is accelerating and techniques have advanced rapidly in the last 5 to 10 years, particu-larly in the areas of dating, identification of characteristics that can be measured, taxonomy, ecological data, multivariate and statistical data analysis, data management, and quality assurance. We focus on the use of biological remains in sediments for monitoring lakes and reservoirs
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
Triclosan, Chlorinated Triclosan Derivative, and Dioxin Levels in Minnesota Lakes
No full textThe Microsoft Excel files (.xls) are available in their original form. For preservation and long-term access, the multiple-tab structure of the excel files have been converted to comma separated value (.csv) files and included here as a zip. The data is identical in these two versions, except that the archived version will not include any special formatting of the excel files (colored cells, bold, etc.) or graphs generated from the data.The data were collected and generated during the period of 2010-2012 by collecting sediment cores from lakes in Minnesota, dating the years the sediment was deposited as a function of depth, and extracting sections of the cores with solvent to determine the levels of triclosan (TCS), chlorinated triclosan derivatives (CTD), and dioxins in the sediment (PCDD). Dating was performed at the St. Croix Watershed Research Station, triclosan and chlorinated triclosan derivative measurements at the University of Minnesota Department of Civil Engineering, and dioxin analysis by Pace Analytical.
The data consists of eight Excel files that include the following tabs 1) accumulation rate and focus corrected accumulation rate of the target contaminants as function of time (FF_Flux), 2) the concentrations of the target contaminants and function of time, 3) the calibration curves of the instruments for triclosan and chlorinated triclosan derivatives, and 4) various statistical analyses (ANOVA).
Note that the further back in time, the deeper the sediment that the sample was derived from.Minnesota Environment and Natural Resources Trust Fund as recommended by the Legislative-Citizen Commission on Minnesota ResourcesNational Science FoundationCBET 0967163Anger, Cale T; Sueper, Charles; Blumentritt, Dylan J; Mcneill, Kristopher; Engstrom, Daniel R; Arnold, William A. (2013). Triclosan, Chlorinated Triclosan Derivative, and Dioxin Levels in Minnesota Lakes. Retrieved from the University Digital Conservancy, http://dx.doi.org/10.13020/D6VC7M
Sedimentary Record of Antibiotic Accumulation in Minnesota Lakes
No full textDeposited here are Excel files containing data regarding the accumulation rates of antibiotics in lake-sediment cores retrieved from select lakes in Minnesota.The widespread detection of antibiotics in the environment is concerning because antibiotics are designed to be effective at small doses. The objective of this work was to quantify the accumulation rates of antibiotics used by humans and animals, spanning several major antibiotic classes (sulfonamides, tetracyclines, fluoroquinolones, and macrolides), in Minnesota lake-sediment cores. Our goal was to determine temporal trends, the major anthropogenic source to these lacustrine systems, and the importance of natural production. A historical record of usage trends for ten human and/or animal-use antibiotics (four sulfonamides, three fluoroquinolones, one macrolide, trimethoprim, and lincomycin) was faithfully captured in the sediment cores. Nine other antibiotics were not detected. Ofloxacin, trimethoprim, sulfapyridine, and sulfamethazine were detected in all of the anthropogenically-impacted studied lakes. Maximum sediment fluxes reached 20.5 ng cm−2 yr−1 (concentration 66.1 ng/g) for ofloxacin, 1.2 ng cm−2 yr−1 (1.2 ng/g) for trimethoprim, 3.3 ng cm−2 yr−1 (11.3 ng/g) for sulfapyridine, and 1.0 ng cm−2 yr−1 (1.6 ng/g) for sulfamethazine, respectively. Natural production of lincomycin may have occurred in one lake at fluxes ranging from 0.4 to 1.8 ng cm−2 yr−1 (0.1 to 5.8 ng/g).Wastewater effluent appears to be the primary source of antibiotics in the studied lakes, with lesser inputs from agricultural activities.Arnold, William A; Kerrigan, Jill F; Sandberg, Kyle; Engstrom, Daniel R; LaPara, Tim. (2018). Sedimentary Record of Antibiotic Accumulation in Minnesota Lakes. Retrieved from the University Digital Conservancy, https://doi.org/10.13020/D6XX03
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
- …
