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215 results on '"St Clair, J."'

3. Genetic architecture of disease resistance and tolerance in Douglas‐fir trees

Author

Singh, Pooja, primary, St Clair, J. Bradley, additional, Lind, Brandon M., additional, Cronn, Richard, additional, Wilhelmi, Nicholas P., additional, Feau, Nicolas, additional, Lu, Mengmeng, additional, Vidakovic, Dragana Obreht, additional, Hamelin, Richard C., additional, Shaw, David C., additional, Aitken, Sally N., additional, and Yeaman, Sam, additional

Published
2024
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6. Nontuberculous Mycobacterial Musculoskeletal Infection Cases from a Tertiary Referral Center, Colorado, USA

Author

Goldstein, Noah, St. Clair, J. Benjamin, Kasperbauer, Shannon H., Daley, Charles L., and Lindeque, Bennie

Subjects
Insmed Inc., Prostheses and implants -- Health aspects, Medical research -- Health aspects, Tigecycline -- Health aspects, Infection -- Care and treatment -- Health aspects, Pharmaceutical industry -- Health aspects, Infection control -- Health aspects, Surgeons -- Health aspects, Surgery, Physicians, Amputation, Orthopedic surgery, Health
Abstract

Nontuberculous mycobacteria (NTM) are opportunistic pathogens found in soil and water and are the sources of an increasing number of infections and illness (1,2). Multiple recent studies have recognized this [...]

Published
2019
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9. Four Years of Airborne Measurements of Wildfire Emissions in California, with a Focus on the Evolution of Emissions During the Soberanes Megafire

Author

Iraci, Laura T, Marrero, J. E, Parworth, C. L, Yates, E. L, Ryoo, J. M, Baker, K, Nguyen, T. K. V, St Clair, J, and Hanisco, T. F

Subjects
Environment Pollution
Abstract

Biomass burning is an important source of trace gases and particles which can influence air quality on local, regional, and global scales. With wildfire events increasing due to changes in land use, increasing population, and climate change, characterizing wildfire emissions and their evolution is vital. In this work we report in situ airborne measurements of carbon dioxide (CO2), methane (CH4), water vapor (H2O), ozone (O3), and formaldehyde (HCHO) from nine wildfire events in California between 2013 and 2016, which were sampled as part of the Alpha Jet Atmospheric eXperiment (AJAX) based at NASA Ames Research Center. One of those fires, the Soberanes Megafire, began on 22 July 2016 and burned for three months. During that time, five flights were executed to sample emissions near and downwind of the Soberanes wildfire. In situ data are used to determine enhancement ratios (ERs), or excess mixing ratio relative to CO2, as well as assess O3 production from the fire. Changes in the emissions as a function of fire evolution are explored. Air quality impacts downwind of the fire are addressed using ground-based monitoring site data, satellite smoke products, and the Community Multiscale Air Quality (CMAQ) photochemical grid model.

Published
2019

12. Morphological Crown Attributes Contributing to Differential Height and Diameter Growth among Families in a Coastal Douglas-Fir Progeny Test: Crown Structural Evidence for Crop Ideotypes.

Author

Joo, Sukhyun, Maguire, Douglas A., St. Clair, J. Bradley, Ye, Terrance Z., and Jayawickrama, Keith J. S.

Subjects
TREE crops, CROPS, FAMILIES, LEAF area, DIAMETER, PLANTATIONS
Abstract

Theoretical tree crop ideotypes have long and narrow live crowns with a high total leaf area. This crown form allows more efficient exploitation of site resources, in part by physically occupying less growing space per unit leaf area and by packing a greater number of trees into a given area. Genetic selection for crop ideotypes has been proposed as a strategy for maximizing productivity per unit area in stands managed under intensive silviculture. The primary objective of this study was to test the relationship between the relative growth performance of different families in a Douglas-fir (Pseudotsuga menziesii var. menziesii [Mirb.] Franco) progeny test and morphological crown attributes that conform to a theoretical crop ideotype. The overarching goal was to identify attributes conferring superior height and diameter growth on families and to facilitate the incorporation of these attributes and associated growth mechanisms into hybrid growth models for intensively managed plantations. Crown structural attributes were measured on destructively sampled trees and averaged for the entire crown and each third of live crown length among families. Multivariate analysis revealed that crown attributes averaged over the entire crown performed best for identifying families with different height and diameter growth, followed successively by the bottom, middle, and top crown third. Trees with relatively short branch lengths and steep branch angles tended to have higher total leaf area per unit crown length (TLACL), and this structural attribute showed a strong positive correlation with cumulative diameter growth. The ratio of crown width to crown length (CWL) was moderately and negatively correlated with cumulative height growth. The families displaying the most rapid diameter growth in this progeny test conformed to a theoretical crop ideotype, while those with the most rapid height growth displayed crown attributes with a less obvious relationship to the crop ideotype concept. TLACL implied one possible mechanism driving genetic gain in Douglas-fir families, given its high heritability and strongly positive correlation with growth performance. Incorporating TLACL as an explanatory variable in diameter growth models could at least partly represent different genetic levels. TLACL is less strongly correlated with height growth rate, so incorporating CWL may better represent genetic effects on height growth models. [ABSTRACT FROM AUTHOR]

Published
2023
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14. Agricultural Fires in the Southeastern U.S. During SEAC4RS: Emissions of Trace Gases and Particles and Evolution of Ozone, Reactive Nitrogen, and Organic Aerosol

Author

Liu, X, Zhang, Y, Huey, L. G, Yokelson, R. J, Wang, Y, Jimenez, J. L, Campuzano-Jost, P, Beyersdorf, A. J, Blake, D. R, Choi, Y, St. Clair, J. M, Crounse, J. D, Day, D. A, Diskin, G. S, Fried, A, Hall, S. R, Hanisco, T. F, King, L. E, Meinardi, S, Mikoviny, T, Palm, B. B, Sachse, G, Thornhill, K. L, Wolfe, G. M, and Ziemba, L. D

Subjects
Environment Pollution
Abstract

Emissions from 15 agricultural fires in the southeastern U.S. were measured from the NASA DC-8 research aircraft during the summer 2013 Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS) campaign. This study reports a detailed set of emission factors (EFs) for 25 trace gases and 6 fine particle species. The chemical evolution of the primary emissions in seven plumes was examined in detail for ~1.2 h. A Lagrangian plume cross-section model was used to simulate the evolution of ozone (O3), reactive nitrogen species, and organic aerosol (OA). Observed EFs are generally consistent with previous measurements of crop residue burning, but the fires studied here emitted high amounts of SO2 and fine particles, especially primary OA and chloride. Filter-based measurements of aerosol light absorption implied that brown carbon (BrC) was ubiquitous in the plumes. In aged plumes, rapid production of O3, peroxyacetyl nitrate (PAN), and nitrate was observed with (Delta)O3/(Delta)CO, (Delta)PAN/(Delta)NOy, and (Delta)nitrate/(Delta)NOy reaching approx. 0.1, approx. 0.3, and approx.0.3. For five selected cases, the model reasonably simulated O3 formation but underestimated PAN formation. No significant evolution of OA mass or BrC absorption was observed. However, a consistent increase in oxygen-to-carbon (O/C) ratios of OA indicated that OA oxidation in the agricultural fire plumes was much faster than in urban and forest fire plumes. Finally, total annual SO2, NOx, and CO emissions from agricultural fires in Arkansas, Louisiana, Mississippi, and Missouri were estimated (within a factor of approx. 2) to be equivalent to approx. 2% SO2 from coal combustion and approx. 1% NOx and approx. 9% CO from mobile sources.

Published
2016
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16. The Universality of Parallel Increasing Quantitative Nodal Burden and Mortality Across Solid Cancers

Author

Nguyen, A.T., primary, Luu, M., additional, Nguyen, V.P., additional, Lu, D.J., additional, Shiao, S.L., additional, Kamrava, M., additional, Atkins, K.M., additional, Mita, A., additional, Scher, K., additional, Spratt, D.E., additional, Faries, M.B., additional, Daskivich, T.J., additional, Lin, D.C., additional, Chen, M.M., additional, Mallen-St. Clair, J., additional, Sandler, H.M., additional, Ho, A.S., additional, and Zumsteg, Z.S., additional

Published
2021
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20. Quantifying Sources and Sinks of Reactive Gases in the Lower Atmosphere Using Airborne Flux Observations

Author

Wolfe, G. M, Hanisco, T. F, Arkinson, H. L, Bui, T. P, Crounse, J. D, Dean-Day, J, Goldstein, A, Guenther, A, Hall, S. R, Huey, G, Jacob, D. J, Karl, T, Kim, P. S, Liu, X, Marvin, M. R, Mikoviny, T, Misztal, P. K, Nguyen, T. B, Peischl, J, Pollack, I, Ryerson, T, St. Clair, J. M, Teng, A, Travis, K. R, Ullmann, K, Wennberg, P.O, and Wisthaler, A

Subjects
Environment Pollution
Abstract

Atmospheric composition is governed by the interplay of emissions, chemistry, deposition, and transport. Substantial questions surround each of these processes, especially in forested environments with strong biogenic emissions. Utilizing aircraft observations acquired over a forest in the southeast U.S., we calculate eddy covariance fluxes for a suite of reactive gases and apply the synergistic information derived from this analysis to quantify emission and deposition fluxes, oxidant concentrations, aerosol uptake coefficients, and other key parameters. Evaluation of results against state-of-the-science models and parameterizations provides insight into our current understanding of this system and frames future observational priorities. As a near-direct measurement of fundamental process rates, airborne fluxes offer a new tool to improve biogenic and anthropogenic emissions inventories, photochemical mechanisms, and deposition parameterizations.

Published
2015
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21. Vertical Transport, Entrainment, and Scavenging Processes Affecting Trace Gases in a Modeled and Observed SEAC⁴RS Case Study

Author

Cuchiara, G. C., Fried, A., Barth, M. C., Bela, M., Homeyer, C. R., Gaubert, B., Walega, J., Weibring, P., Richter, D., Wennberg, P., Crounse, J. D., Kim, M., Diskin, G., Hanisco, T. M., Wolfe, G. M., Beyersdorf, A., Peischl, J., Pollack, I. B., St. Clair, J. M., Woods, S., Tanelli, S., Bui, T. P., Dean‐Day, J., Huey, G. L., and Heath, N.

Abstract

The convectively driven transport of soluble trace gases from the lower to the upper troposphere can occur on timescales of less than an hour, and recent studies suggest that microphysical scavenging is the dominant removal process of tropospheric ozone precursors. We examine the processes responsible for vertical transport, entrainment, and scavenging of soluble ozone precursors (formaldehyde and peroxides) for midlatitude convective storms sampled on 2 September 2013 during the Studies of Emissions, Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC⁴RS) study. Cloud‐resolving simulations using the Weather Research and Forecasting with Chemistry model combined with aircraft measurements were performed to understand the effect of entrainment, scavenging efficiency (SE), and ice physics processes on these trace gases. Analysis of the observations revealed that the SEs of formaldehyde (43–53%) and hydrogen peroxide (~80–90%) were consistent between SEAC⁴RS storms and the severe convection observed during the Deep Convective Clouds and Chemistry Experiment (DC3) campaign. However, methyl hydrogen peroxide SE was generally smaller in the SEAC⁴RS storms (4%–27%) compared to DC3 convection. Predicted ice retention factors exhibit different values for some species compared to DC3, and we attribute these differences to variations in net precipitation production. The analyses show that much larger production of precipitation between condensation and freezing levels for DC3 severe convection compared to smaller SEAC⁴RS storms is largely responsible for the lower amount of soluble gases transported to colder temperatures, reducing the amount of soluble gases which eventually interact with cloud ice particles.

Published
2020

25. Vertical Transport, Entrainment, and Scavenging Processes Affecting Trace Gases in a Modeled and Observed SEAC 4 RS Case Study

Author

Cuchiara, G. C., primary, Fried, A., additional, Barth, M. C., additional, Bela, M., additional, Homeyer, C. R., additional, Gaubert, B., additional, Walega, J., additional, Weibring, P., additional, Richter, D., additional, Wennberg, P., additional, Crounse, J., additional, Kim, M., additional, Diskin, G., additional, Hanisco, T. F., additional, Wolfe, G. M., additional, Beyersdorf, A., additional, Peischl, J., additional, Pollack, I. B., additional, St. Clair, J. M., additional, Woods, S., additional, Tanelli, S., additional, Bui, T. V., additional, Dean‐Day, J., additional, Huey, L. G., additional, and Heath, N., additional

Published
2020
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28. Exploring Oxidation in the Remote Free Troposphere: Insights From Atmospheric Tomography (ATom)

Author

Brune, W. H., primary, Miller, D. O., additional, Thames, A. B., additional, Allen, H. M., additional, Apel, E. C., additional, Blake, D. R., additional, Bui, T. P., additional, Commane, R., additional, Crounse, J. D., additional, Daube, B. C., additional, Diskin, G. S., additional, DiGangi, J. P., additional, Elkins, J. W., additional, Hall, S. R., additional, Hanisco, T. F., additional, Hannun, R. A., additional, Hintsa, E. J., additional, Hornbrook, R. S., additional, Kim, M. J., additional, McKain, K., additional, Moore, F. L., additional, Neuman, J. A., additional, Nicely, J. M., additional, Peischl, J., additional, Ryerson, T. B., additional, St. Clair, J. M., additional, Sweeney, C., additional, Teng, A. P., additional, Thompson, C., additional, Ullmann, K., additional, Veres, P. R., additional, Wennberg, P. O., additional, and Wolfe, G. M., additional

Published
2020
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33. Vertical Transport, Entrainment, and Scavenging Processes Affecting Trace Gases in a Modeled and Observed SEAC4RS Case Study.

Author

Cuchiara, G. C., Fried, A., Barth, M. C., Bela, M., Homeyer, C. R., Gaubert, B., Walega, J., Weibring, P., Richter, D., Wennberg, P., Crounse, J., Kim, M., Diskin, G., Hanisco, T. F., Wolfe, G. M., Beyersdorf, A., Peischl, J., Pollack, I. B., St. Clair, J. M., and Woods, S.

Subjects
TRACE gases, TROPOSPHERE, METEOROLOGICAL precipitation, CONVECTION (Meteorology), HYDROGEN peroxide
Abstract

The convectively driven transport of soluble trace gases from the lower to the upper troposphere can occur on timescales of less than an hour, and recent studies suggest that microphysical scavenging is the dominant removal process of tropospheric ozone precursors. We examine the processes responsible for vertical transport, entrainment, and scavenging of soluble ozone precursors (formaldehyde and peroxides) for midlatitude convective storms sampled on 2 September 2013 during the Studies of Emissions, Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS) study. Cloud‐resolving simulations using the Weather Research and Forecasting with Chemistry model combined with aircraft measurements were performed to understand the effect of entrainment, scavenging efficiency (SE), and ice physics processes on these trace gases. Analysis of the observations revealed that the SEs of formaldehyde (43–53%) and hydrogen peroxide (~80–90%) were consistent between SEAC4RS storms and the severe convection observed during the Deep Convective Clouds and Chemistry Experiment (DC3) campaign. However, methyl hydrogen peroxide SE was generally smaller in the SEAC4RS storms (4%–27%) compared to DC3 convection. Predicted ice retention factors exhibit different values for some species compared to DC3, and we attribute these differences to variations in net precipitation production. The analyses show that much larger production of precipitation between condensation and freezing levels for DC3 severe convection compared to smaller SEAC4RS storms is largely responsible for the lower amount of soluble gases transported to colder temperatures, reducing the amount of soluble gases which eventually interact with cloud ice particles. Key Points: Formaldehyde and hydrogen peroxide scavenging efficiencies are consistent with literature, while methyl hydrogen peroxide is generally smallerHighly soluble hydrogen peroxide is mostly depleted between cloud base and the freezing level, that is, the warm region of the stormRetention of dissolved trace gases in frozen precipitation seems to be more important for moderately soluble trace gases [ABSTRACT FROM AUTHOR]

Published
2020
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38. Agricultural fires in the southeastern U.S. during SEAC⁴RS: Emissions of trace gases and particles and evolution of ozone, reactive nitrogen, and organic aerosol

Author

Liu, Xiaoxi, Zhang, Y., Huey, L. G., Yokelson, R.J., Wang, Y., Jimenez, J. L., Campuzano-Jost, P., Beyersdorf, A.J., Blake, D.R., Choi, Y., St. Clair, J. M., Crounse, J.D., Day, D. A., Diskin, G.S., Fried, A., Hall, S. R., Hanisco, T. F., King, L. E., Meinardi, S., Mikoviny, T., Palm, B. B., Peischl, J., Perring, A. E., Pollack, I. B., Ryerson, T. B., Sachse, G., Schwarz, J. P., Simpson, I. J., Tanner, D. J., Thornhill, K. L., Ullmann, K., Weber, R. J., Wennberg, P. O., Wisthaler, A., Wolfe, G. M., and Ziemba, L. D.

Abstract

Emissions from 15 agricultural fires in the southeastern U.S. were measured from the NASA DC‐8 research aircraft during the summer 2013 Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC⁴RS) campaign. This study reports a detailed set of emission factors (EFs) for 25 trace gases and 6 fine particle species. The chemical evolution of the primary emissions in seven plumes was examined in detail for ~1.2 h. A Lagrangian plume cross‐section model was used to simulate the evolution of ozone (O₃), reactive nitrogen species, and organic aerosol (OA). Observed EFs are generally consistent with previous measurements of crop residue burning, but the fires studied here emitted high amounts of SO₂ and fine particles, especially primary OA and chloride. Filter‐based measurements of aerosol light absorption implied that brown carbon (BrC) was ubiquitous in the plumes. In aged plumes, rapid production of O₃, peroxyacetyl nitrate (PAN), and nitrate was observed with ΔO₃/ΔCO, ΔPAN/ΔNOy, and Δnitrate/ΔNOy reaching ~0.1, ~0.3, and ~0.3. For five selected cases, the model reasonably simulated O₃ formation but underestimated PAN formation. No significant evolution of OA mass or BrC absorption was observed. However, a consistent increase in oxygen‐to‐carbon (O/C) ratios of OA indicated that OA oxidation in the agricultural fire plumes was much faster than in urban and forest fire plumes. Finally, total annual SO₂, NOₓ , and CO emissions from agricultural fires in Arkansas, Louisiana, Mississippi, and Missouri were estimated (within a factor of ~2) to be equivalent to ~2% SO₂ from coal combustion and ~1% NOₓ and ~9% CO from mobile sources.

Published
2016
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46. Speciation of OH reactivity above the canopy of an isoprene-dominated forest

Author

Kaiser, J., primary, Skog, K. M., additional, Baumann, K., additional, Bertman, S. B., additional, Brown, S. B., additional, Brune, W. H., additional, Crounse, J. D., additional, de Gouw, J. A., additional, Edgerton, E. S., additional, Feiner, P. A., additional, Goldstein, A. H., additional, Koss, A., additional, Misztal, P. K., additional, Nguyen, T. B., additional, Olson, K. F., additional, St. Clair, J. M., additional, Teng, A. P., additional, Toma, S., additional, Wennberg, P. O., additional, Wild, R. J., additional, Zhang, L., additional, and Keutsch, F. N., additional

Published
2016
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47. Agricultural fires in the southeastern U.S. during SEAC 4 RS: Emissions of trace gases and particles and evolution of ozone, reactive nitrogen, and organic aerosol

Author

Liu, Xiaoxi, primary, Zhang, Y., additional, Huey, L. G., additional, Yokelson, R. J., additional, Wang, Y., additional, Jimenez, J. L., additional, Campuzano‐Jost, P., additional, Beyersdorf, A. J., additional, Blake, D. R., additional, Choi, Y., additional, St. Clair, J. M., additional, Crounse, J. D., additional, Day, D. A., additional, Diskin, G. S., additional, Fried, A., additional, Hall, S. R., additional, Hanisco, T. F., additional, King, L. E., additional, Meinardi, S., additional, Mikoviny, T., additional, Palm, B. B., additional, Peischl, J., additional, Perring, A. E., additional, Pollack, I. B., additional, Ryerson, T. B., additional, Sachse, G., additional, Schwarz, J. P., additional, Simpson, I. J., additional, Tanner, D. J., additional, Thornhill, K. L., additional, Ullmann, K., additional, Weber, R. J., additional, Wennberg, P. O., additional, Wisthaler, A., additional, Wolfe, G. M., additional, and Ziemba, L. D., additional

Published
2016
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49. Convective transport and scavenging of peroxides by thunderstorms observed over the central U.S. during DC3

Author

Barth, M. C., primary, Bela, M. M., additional, Fried, A., additional, Wennberg, P. O., additional, Crounse, J. D., additional, St. Clair, J. M., additional, Blake, N. J., additional, Blake, D. R., additional, Homeyer, C. R., additional, Brune, W. H., additional, Zhang, L., additional, Mao, J., additional, Ren, X., additional, Ryerson, T. B., additional, Pollack, I. B., additional, Peischl, J., additional, Cohen, R. C., additional, Nault, B. A., additional, Huey, L. G., additional, Liu, X., additional, and Cantrell, C. A., additional

Published
2016
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