69 research outputs found
U.S. nitrogen science plan focuses collaborative efforts
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95241/1/eost15156.pd
Measurements of ambient HONO concentrations and vertical HONO flux above a northern Michigan forest canopy
Systems have been developed and deployed at a North Michigan forested site to measure ambient HONO and vertical HONO flux. The modified HONO measurement technique is based on aqueous scrubbing of HONO using a coil sampler, followed by azo dye derivatization and detection using a long-path absorption photometer (LPAP). A Na<sub>2</sub>CO<sub>3</sub>-coated denuder is used to generate "zero HONO" air for background correction. The lower detection limit of the method, defined by 3 times of the standard deviation of the signal, is 1 pptv for 1-min averages, with an overall uncertainty of &plusmn;(1 + 0.05 [HONO]) pptv. The HONO flux measurement technique has been developed based on the relaxed eddy accumulation approach, deploying a 3-D sonic anemometer and two HONO measurement systems. The overall uncertainty is estimated to be within &plusmn;(8 &times; 10<sup>&minus;8</sup> + 0.15 <i>F</i><sub>HONO</sub>) mol m<sup>−2</sup> h<sup>−1</sup>, with a 20-min averaged data point per 30 min. Ambient HONO and vertical HONO flux were measured simultaneously at the PROPHET site from 17 July to 7 August 2008. The forest canopy was found to be a net HONO source, with a mean upward flux of 0.37 &times; 10<sup>&minus;6</sup> moles m<sup>−2</sup> h<sup>−1</sup>. The HONO flux reached a maximal mean of ~0.7 &times; 10<sup>&minus;6</sup> moles m<sup>−2</sup> h<sup>−1</sup> around solar noon, contributing a major fraction to the HONO source strength required to sustain the observed ambient concentration of ~70 pptv. There were no significant correlations between [NO<sub>x</sub>] and daytime HONO flux and between <i>J</i><sub>NO<sub>2</sub></sub> &times; [NO<sub>2</sub>] and HONO flux, suggesting that NO<sub>x</sub> was not an important precursor responsible for HONO daytime production on the forest canopy surface in this low-NO<sub>x</sub> rural environment. Evidence supports the hypothesis that photolysis of HNO<sub>3</sub> deposited on the forest canopy surface is a major daytime HONO source
Loss, Bereavement and Creativity: Meanings and Uses
Within the field of death and bereavement studies, the assumption that loss and bereavement provide the spur to creativity has become so widespread as to assume the status of a conventional wisdom. With this in mind, this article surveys the literature on the topic, extant, and contemporary, revealing its diffuseness as well as the multidisciplinary synergies produced by those working in disparate academic and clinical fields of practice. In so doing, the article explores what it means to be creative in the context of loss and bereavement, the potential for self-development and personal growth offered by creativity and loss, the theoretical premises linking creativity and loss, and the application and challenges for creative therapies in the institutional context of hospice and palliative car
Speciation of OH reactivity above the canopy of an isoprene-dominated forest
Measurements of OH reactivity, the inverse lifetime of the OH radical, can provide a top–down estimate of the total amount of reactive carbon in an air mass. Using a comprehensive measurement suite, we examine the measured and modeled OH reactivity above an isoprene-dominated forest in the southeast United States during the 2013 Southern Oxidant and Aerosol Study (SOAS) field campaign. Measured and modeled species account for the vast majority of average daytime reactivity (80–95 %) and a smaller portion of nighttime and early morning reactivity (68–80 %). The largest contribution to total reactivity consistently comes from primary biogenic emissions, with isoprene contributing ∼ 60 % in the afternoon, and ∼ 30–40 % at night and monoterpenes contributing ∼ 15–25 % at night. By comparing total reactivity to the reactivity stemming from isoprene alone, we find that ∼ 20 % of the discrepancy is temporally related to isoprene reactivity, and an additional constant ∼ 1 s^(−1) offset accounts for the remaining portion. The model typically overestimates measured OVOC concentrations, indicating that unmeasured oxidation products are unlikely to influence measured OH reactivity. Instead, we suggest that unmeasured primary emissions may influence the OH reactivity at this site
Cluster analysis of the organic peaks in bulk mass spectra obtained during the 2002 New England Air Quality Study with an Aerodyne aerosol mass spectrometer
International audienceWe applied hierarchical cluster analysis to an Aerodyne aerosol mass spectrometer (AMS) bulk mass spectral dataset collected aboard the NOAA research vessel Ronald H. Brown during the 2002 New England Air Quality Study off the east coast of the United States. Emphasizing the organic peaks, the cluster analysis yielded a series of categories that are distinguishable with respect to their mass spectra and their occurrence as a function of time. The differences between the categories mainly arise from relative intensity changes rather than from the presence or absence of specific peaks. The most frequent category exhibits a strong signal at m/z 44 and represents oxidized organic matter most probably originating from both, anthropogenic as well as biogenic sources. On the basis of spectral and trace gas correlations, the second most common category with strong signals at m/z 29, 43, and 44 contains contributions from isoprene oxidation products. The third through the fifth most common categories have peak patterns characteristic of monoterpene oxidation products and were most frequently observed when air masses from monoterpene rich regions were sampled. Taken together, the second through the fifth most common categories represent as much as 5 µg/m3 organic aerosol mass ? 17% of the total organic mass ? that can be attributed to biogenic sources. These numbers have to be viewed as lower limits since the most common category was attributed to anthropogenic sources for this calculation. The cluster analysis was also very effective in identifying a few contaminated mass spectra that were not removed during pre-processing. This study demonstrates that hierarchical clustering is a useful tool to analyze the complex patterns of the organic peaks in bulk aerosol mass spectra from a field study
Behind the stiff upper lip: war narratives of older men with dementia.
The concept of the stiff upper lip stands as a cultural metaphor for the repression and figurative ¿biting back¿ of traumatic experience, particularly in military contexts. For men born in the first half of the 20th century, maintaining a stiff upper lip involved the ability to exert high levels of cognitive control over the subjective, visceral and emotional domains of experience. In the most common forms of dementia, which affect at least one in five men now in their 80s and 90s, this cognitive control is increasingly lost. One result is that, with the onset of dementia, men who have in the intervening years maintained a relative silence about their wartime experiences begin to disclose detailed memories of such events, in some cases for the first time. This article draws on narrative biographical data from three men with late-onset dementia who make extensive reference to their experience of war. The narratives of Sid, Leonard and Nelson are used to explore aspects of collective memory of the two World Wars, and the socially constructed masculinities imposed on men who grew up and came of age during those decades. The findings show that in spite of their difficulties with short term memory, people with dementia can contribute rich data to cultural studies research. Some aspects of the narratives discussed here may also be considered to work along the line of the counter-hegemonic, offering insights into lived experiences of war that have been elided in popular culture in the post-War years
Speciation of OH reactivity above the canopy of an isoprene-dominated forest
Measurements of OH reactivity, the inverse lifetime of the OH radical, can provide a top–down estimate of the total amount of reactive carbon in an air mass. Using a comprehensive measurement suite, we examine the measured and modeled OH reactivity above an isoprene-dominated forest in the southeast United States during the 2013 Southern Oxidant and Aerosol Study (SOAS) field campaign. Measured and modeled species account for the vast majority of average daytime reactivity (80–95 %) and a smaller portion of nighttime and early morning reactivity (68–80 %). The largest contribution to total reactivity consistently comes from primary biogenic emissions, with isoprene contributing ∼ 60 % in the afternoon, and ∼ 30–40 % at night and monoterpenes contributing ∼ 15–25 % at night. By comparing total reactivity to the reactivity stemming from isoprene alone, we find that ∼ 20 % of the discrepancy is temporally related to isoprene reactivity, and an additional constant ∼ 1 s^(−1) offset accounts for the remaining portion. The model typically overestimates measured OVOC concentrations, indicating that unmeasured oxidation products are unlikely to influence measured OH reactivity. Instead, we suggest that unmeasured primary emissions may influence the OH reactivity at this site
Importance of biogenic volatile organic compounds to acyl peroxy nitrates (APN) production in the southeastern US during SOAS 2013
Gas-phase atmospheric concentrations of peroxyacetyl nitrate (PAN),
peroxypropionyl nitrate (PPN), and peroxymethacryloyl nitrate (MPAN) were
measured on the ground using a gas chromatograph electron capture detector
(GC-ECD) during the Southern Oxidants and Aerosols Study (SOAS) 2013 campaign
(1 June to 15 July 2013) in Centreville, Alabama, in order to study
biosphere–atmosphere interactions. Average levels of PAN, PPN, and MPAN were
169, 5, and 9 pptv, respectively, and the sum accounts for an average of
16 % of NOy during the daytime (10:00 to 16:00 local
time). Higher concentrations were seen on average in air that came to the
site from the urban NOx sources to the north. PAN levels
were the lowest observed in ground measurements over the past two decades in
the southeastern US. A multiple regression analysis indicates that biogenic
volatile organic compounds (VOCs) account for 66 % of PAN formation
during this study. Comparison of this value with a 0-D model simulation of
peroxyacetyl radical production indicates that at least 50 % of PAN
formation is due to isoprene oxidation. MPAN has a statistical correlation
with isoprene hydroxynitrates (IN). Organic aerosol mass increases with
gas-phase MPAN and IN concentrations, but the mass of organic nitrates in
particles is largely unrelated to MPAN.</p
Liquid networks and the metaphysics of flux: ontologies of flow in an age of speed and mobility
It is common for social theorists to utilize the metaphors of ‘flow’, ‘fluidity’, and ‘liquidity’ in order to substantiate the ways in which speed and mobility form the basis for a new kind of information or network society. Yet rarely have these concepts been sufficiently theorized in order to establish their relevance or appropriateness. This article contends that the notion of flow as utilized in social theory is profoundly metaphysical in nature, and needs to be judged as such. Beginning with a discussion of the accelerating timescape that characterizes the network society, it will then move on to examine three main issues with this ‘metaphysics of flux’. First, that the concept of flows unjustly privileges the process of becoming and, as a result, is unable to account for the materiality, substantiality, and agency of the objects being mobilized, and the contingency of their mediation. Second, that it posits the accelerating tendencies of capital as an ontological inevitability, thus discounting resistance to such forces. Finally, that it ignores the human faculty for reason and speculative thought in developing alternative means of political praxis. The solution, it will be argued, is not to abandon metaphysical accounts of the network society, but rather to challenge those accounts that, in exhibiting a crude empiricism, work to justify the status quo
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