1,721,036 research outputs found
Impacts of Biomass Burning on Ozone, Particulate Matter, and Carbon Dioxide in the Northwest U.S.
No full textThesis (Ph.D.)--University of Washington, 2018Wildfires (or Biomass Burning events) in the northwest U.S. have been increasing in size and frequency throughout the last few decades. This significantly affects vulnerable populations through hazardous fine particulate matter (diameter < 2.5 µm [PM2.5]) and/or ozone (O3) exposure, loss of habitat and homes, and causes disruption of outdoor activities throughout the summer season. While the U.S. EPA regulates many hazardous pollutants through the National Ambient Air Quality Standards (NAAQS) for the protection of human health, during wildfire events, these pollutants can reach dangerous levels. In most cases, these exceedances of the NAAQS during wildfire events cannot be controlled. While we cannot completely control wildfires, we can endeavor to understand how the emissions from these events affects our air quality. In order to accomplish this, we must first determine how to trace and attribute different pollution events to wildfire emissions. This goal is highlighted by the probability of wildfire occurrence, which is predicted to increase through the end of the century. This dissertation provides results from three studies which investigate the impact of wildfires in the northwest U.S. by tracing their emissions. First, I investigate the role of carbon dioxide (CO2) and its use as a tracer for biomass burning. Secondly, I use historical PM2.5 data to determine which areas in the U.S. are seeing significant increases in PM due to wildfires. Lastly, I investigate the attribution of wildfire-influence to high O3 days seen in urban areas using observations and modelling. To investigate the role of CO2 as a tracer for biomass burning, I used data from the Mount Bachelor Observatory (MBO) in central Oregon for 2012-2014. First I investigated the variations in CO2 in the free troposphere (FT) and boundary layer (BL) to determine variations due to wildfires, different transport patterns, and seasonal variations. For all seasons, I found that FT air had a higher average CO2 mixing ratio than BL air. BL air was most often observed during the afternoon and evening (12-20 PST), while FT air was most often observed during the night and early morning (20-8 PST) due to the role of up-slope and down-slope flow, respectively. Fall and summer showed the lowest mixing ratios of CO2, while winter and spring showed the highest due to uptake and respiration of vegetation, respectively. The maximum daily change in CO2 was found during spring and summer. Using HYSPLIT back-trajectories and cluster analyses during spring months, I determined that the highest CO2 mixing ratios were also associated with the highest O3 and lowest water vapor mixing ratios. I also looked at four case studies (one long-range transport and three wildfire events) that showed significant variations in CO2. During one of the wildfire events, I saw the expected profile, large enhancements of CO2 that were well correlated with carbon monoxide (CO). However, in a different wildfire case, CO2 decreased during the event. This was likely caused by uptake of CO2 during BL transport, which counteracted the enhancements from wildfire emissions. This event also provided insight into the variations of a typically used wildfire tracer, CO2, and showed that it is not always reliable. Significant variations in downwind CO2 mixing ratios may also influence metrics that use CO2 in the calculations, such as modified combustion efficiency (MCE). Assessing historical data from rural monitoring sites (IMPROVE sites) across the contiguous U.S., I evaluated PM2.5 trends during 1988-2016. To calculate trends in the policy-relevant 98th quantile of PM2.5¬, I use Quantile Regression (QR). This methodology allows me to estimate changes, not only in the mean, but in the full distribution. I also use Kriging and Gaussian Geostatistical Simulations to interpolate changes in PM2.5 trends between monitoring sites. Overall, the 98th quantile PM2.5 showed a positive trend in the northwest U.S. (average = 0.24 ± 0.15 µg/m3/yr [± 95% CI]). This was in contrast with overall negative trends in the 98th quantile PM2.5 observed in the rest of the country (average -0.56 ± 0.10 µg/m3/yr). The decrease in the rest of the country is likely due to the reduction in anthropogenic emissions seen in recent years. I also evaluated 98th quantile trends in total carbon (TC) and sulfate across the country to examine the effects of wildfire and anthropogenic emissions on the PM2.5 trends, respectively. This analysis showed a positive trend in TC and no trend in sulfate across the northwest U.S., which confirmed the influence of wildfire activity on positive PM2.5 trends. I also evaluated daily MODIS Aqua aerosol optical depth (AOD) data for 2002-2017 to compare with ground-based trends. Comparing the IMPROVE and MODIS data, I found positive 98th quantile PM2.5 trends in the Northwest (1.94 ± 1.00 & 2.12 ± 0.81 %/yr, respectively) and negative trends throughout the rest of the country (-2.81 ± 0.43 & -1.20 ± 0.51 %/yr, respectively) through 2016. If I include 2017 MODIS data, the trend in the Northwest is even greater due to 2017 being a very high wildfire year. Overall, these results indicated a decrease in PM2.5 over a majority of the country, while wildfires influence an increase in the 98th quantile PM2.5 trends across the Northwest. In order to investigate wildfire impacts on O3 in an urban area, I use data from the St. Luke’s site in Meridian, ID during a summer intensive campaign in 2017. To identify wildfire influenced periods, I calculate a wildfire criterion based on the NOAA Hazard Mapping System (HMS) smoke product and historical PM2.5 data at St. Luke’s. I also ran a Generalized Additive Model (GAM), which uses multiple prediction variables (i.e., meteorological and back-trajectory data) to model a response variable (i.e., MDA8 O3). When the GAM prediction significantly differs from observed data, I investigate unusual sources of O3 (such as wildfire influences) in this urban area. During the 2017 summer campaign, I found that peroxyacetyl nitrate (PAN), reactive nitrogen (NOy), and maximum daily 8 hour averaged (MDA8) O3 are significantly enhanced during wildfire smoke events compared with non-smoke periods (56%, 38%, and 28%, respectively). I also calculate enhancement ratios (ERs) to assist in the identification of wildfire plumes for ΔPM2.5/ΔCO, ΔNOy/ΔCO, ΔPAN/ΔNOy, and ΔPAN/ΔCO. The 95% confidence intervals for these ERs are found to be 0.123 – 0.133 µg/m3/ppbv, 0.058 – 0.066 ppbv/ppbv, 0.150 – 0.191 ppbv/ppbv, and 3.02 – 3.76 ppbv/ppmv, respectively, for wildfire influenced events. These ERs generally reflect the accepted literature values considering some differences due to mixing with urban air instead of sampling in a non-polluted environment. Using historical data from the St. Luke’s site for 2006-2017, I determine the change in O3 production on smoke vs. non-smoke days. During non-smoke days, I observed a decrease in MDA8 O3 with increasing PM2.5, which was attributed to high NOx mixing ratios and NOx-titration of O3. On smoke days, however, I observed enhancements in O3 production up to high smoke levels (PM2.5 ~ 60-70 µg/m3). At higher PM2.5 concentrations, there is a reduction in average MDA8 O3. Additionally, the GAM shows that while only 4% of days are classified as smoke days, these days show significantly higher residuals than non-smoke days. This suggests that the enhancement in O3 on smoke days is not associated with standard meteorology or transport variables. I also examine four wildfire-influenced high O3 events in this urban area to evaluate the significantly variable conditions that result. In two cases, I investigate smoke days that show significant O3 enhancement and moderate PM2.5 concentrations. These cases suggest that ERs, such as ΔPM2.5/ΔCO and ΔNOy/ΔCO, are less useful in determining wildfire influence in an urban area on moderate smoke days. Another case shows reduced O3 production during a very high, 3-day smoke event (PM2.5 > 70 µg/m3). The day after this high smoke period, a 20 ppbv enhancement in MDA8 O3 is observed in moderate smoke concentrations. The enhancement in MDA8 O3 during moderate smoke immediately following a high smoke periods implies a reduction in O3 production efficiency during high smoke concentrations. These results indicate that wildfire influenced O3 enhancements are highly variable in urban areas but generally increase up to around 60 µg/m3 of PM2.5, after which they decrease at very high smoke concentrations. This analysis also suggests that multiple tracer methodologies, such as GAM results, back-trajectories, and PAN mixing ratios, are effective at characterizing wildfire influence on MDA8 O3 in urban areas. Results from this dissertation have important implications for the identification of wildfire influences in urban and rural areas. They suggest the current suite of measurements taken may be ill-equipped or incomplete to fully investigate wildfire influences. Current CO2 and MCE criteria for wildfire influence may be biased by BL loss of CO2 during transport. ERs typical for wildfires are useful in urban areas when smoke influence is large, but less useful at moderate smoke levels due to high background concentrations of other urban pollutants already within the area. Additionally, highly variable PM2.5 concentrations in wildfire plumes can affect O3 production. While PM2.5 trends are decreasing throughout most of the U.S., policy-relevant 98th quantile PM2.5 shows an increase in the Northwest due to wildfire influence. With a predicted increase in wildfires through the end of the century, it is vitally important to develop methods to assess when wildfire emission are impacting an area. This could be achieved by developing an instrument to measure specific wildfire tracers, such as acetonitrile or a suite of volatile organic compounds (VOCs). Although there are instruments that can already measure these types of compounds, this instrument would need to be specific to wildfires compounds and not require special training or equipment to operate. This would allow cities/states/researchers to positively or negatively trace the influence of wildfires at low operational and personnel cost. This instrument would greatly expand our understanding of the impacts on air pollution due to wildfire emissions
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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