905 results on '"Hall, Samuel"'
Search Results
2. Synthesizing evidence for the external cycling of NOx in high- to low-NOx atmospheres.
- Author
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Ye, Chunxiang, Zhou, Xianliang, Zhang, Yingjie, Wang, Youfeng, Wang, Jianshu, Zhang, Chong, Woodward-Massey, Robert, Cantrell, Christopher, Mauldin, Roy, Campos, Teresa, Hornbrook, Rebecca, Ortega, John, Apel, Eric, Haggerty, Julie, Hall, Samuel, Ullmann, Kirk, Weinheimer, Andrew, Stutz, Jochen, Karl, Thomas, Song, Shaojie, Guenther, Alex, and Smith, James
- Abstract
External cycling regenerating nitrogen oxides (NOx ≡ NO + NO2) from their oxidative reservoir, NOz, is proposed to reshape the temporal-spatial distribution of NOx and consequently hydroxyl radical (OH), the most important oxidant in the atmosphere. Here we verify the in situ external cycling of NOx in various environments with nitrous acid (HONO) as an intermediate based on synthesized field evidence collected onboard aircraft platform at daytime. External cycling helps to reconcile stubborn underestimation on observed ratios of HONO/NO2 and NO2/NOz by current chemical model schemes and rationalize atypical diurnal concentration profiles of HONO and NO2 lacking noontime valleys specially observed in low-NOx atmospheres. Perturbation on the budget of HONO and NOx by external cycling is also found to increase as NOx concentration decreases. Consequently, model underestimation of OH observations by up to 41% in low NOx atmospheres is attributed to the omission of external cycling in models.
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- 2023
3. An observation-based, reduced-form model for oxidation in the remote marine troposphere.
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Baublitz, Colleen, Fiore, Arlene, Ludwig, Sarah, Nicely, Julie, Wolfe, Glenn, Murray, Lee, Commane, Róisín, Prather, Michael, Anderson, Daniel, Correa, Gustavo, Duncan, Bryan, Follette-Cook, Melanie, Westervelt, Daniel, Bourgeois, Ilann, Brune, William, Bui, T, DiGangi, Joshua, Diskin, Glenn, Hall, Samuel, McKain, Kathryn, Miller, David, Peischl, Jeff, Thames, Alexander, Thompson, Chelsea, Ullmann, Kirk, and Wofsy, Steven
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atmospheric oxidation ,hydroxyl radical ,marine troposphere ,tropospheric chemistry - Abstract
The hydroxyl radical (OH) fuels atmospheric chemical cycling as the main sink for methane and a driver of the formation and loss of many air pollutants, but direct OH observations are sparse. We develop and evaluate an observation-based proxy for short-term, spatial variations in OH (ProxyOH) in the remote marine troposphere using comprehensive measurements from the NASA Atmospheric Tomography (ATom) airborne campaign. ProxyOH is a reduced form of the OH steady-state equation representing the dominant OH production and loss pathways in the remote marine troposphere, according to box model simulations of OH constrained with ATom observations. ProxyOH comprises only eight variables that are generally observed by routine ground- or satellite-based instruments. ProxyOH scales linearly with in situ [OH] spatial variations along the ATom flight tracks (median r2 = 0.90, interquartile range = 0.80 to 0.94 across 2-km altitude by 20° latitudinal regions). We deconstruct spatial variations in ProxyOH as a first-order approximation of the sensitivity of OH variations to individual terms. Two terms modulate within-region ProxyOH variations-water vapor (H2O) and, to a lesser extent, nitric oxide (NO). This implies that a limited set of observations could offer an avenue for observation-based mapping of OH spatial variations over much of the remote marine troposphere. Both H2O and NO are expected to change with climate, while NO also varies strongly with human activities. We also illustrate the utility of ProxyOH as a process-based approach for evaluating intermodel differences in remote marine tropospheric OH.
- Published
- 2023
4. Researching Catastrophic Environmental Changes on Northern Coastlines: A Geoarchaeological Case Study from the Shetland Islands
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Bigelow, Gerald F., Ferrante, Stephanie M., Hall, Samuel T., Kimball, Lisa M., Proctor, Robert E., and Remington, Sue L.
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- 2011
- Full Text
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5. Characterizing Molecule-Metal Surface Chemistry with Ab-Initio Simulation of X-ray Absorption and Photoemission Spectra
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Hall, Samuel J., Klein, Benedikt P., and Maurer, Reinhard J.
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Condensed Matter - Materials Science - Abstract
X-ray photoemission and x-ray absorption spectroscopy are important techniques to characterize chemical bonding at surfaces and are often used to identify the strength and nature of adsorbate-substrate interactions. In this study, we judge the ability of x-ray spectroscopic techniques to identify different regimes of chemical bonding at metal-organic interfaces. To achieve this, we sample different interaction strength regimes in a comprehensive and systematic way by comparing two topological isomers, azulene and naphthalene, adsorbed on three metal substrates with varying reactivity, namely the (111) facets of Ag, Cu, and Pt. Using density functional theory, we simulate core-level binding energies and x-ray absorption spectra of the molecular carbon species. The simulated spectra reveal three distinct characteristics based on the molecule-specific spectral features which we attribute to types of surface chemical bonding with varying strength. We find that weak physisorption only leads to minor changes compared to the gas-phase spectra, weak chemisorption leads to charge transfer and significant spectral changes, while strong chemisorption leads to a loss of the molecule-specific features in the spectra. The classification we provide is aimed at assisting interpretation of experimental x-ray spectra for complex metal-organic interfaces.
- Published
- 2022
- Full Text
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6. Autonomous Passage Planning for a Polar Vessel
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Smith, Jonathan D., Hall, Samuel, Coombs, George, Byrne, James, Thorne, Michael A. S., Brearley, J. Alexander, Long, Derek, Meredith, Michael, and Fox, Maria
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Computer Science - Robotics - Abstract
We introduce a method for long-distance maritime route planning in polar regions, taking into account complex changing environmental conditions. The method allows the construction of optimised routes, describing the three main stages of the process: discrete modelling of the environmental conditions using a non-uniform mesh, the construction of mesh-optimal paths, and path smoothing. In order to account for different vehicle properties we construct a series of data driven functions that can be applied to the environmental mesh to determine the speed limitations and fuel requirements for a given vessel and mesh cell, representing these quantities graphically and geospatially. In describing our results, we demonstrate an example use case for route planning for the polar research ship the RRS Sir David Attenborough (SDA), accounting for ice-performance characteristics and validating the spatial-temporal route construction in the region of the Weddell Sea, Antarctica. We demonstrate the versatility of this route construction method by demonstrating that routes change depending on the seasonal sea ice variability, differences in the route-planning objective functions used, and the presence of other environmental conditions such as currents. To demonstrate the generality of our approach, we present examples in the Arctic Ocean and the Baltic Sea. The techniques outlined in this manuscript are generic and can therefore be applied to vessels with different characteristics. Our approach can have considerable utility beyond just a single vessel planning procedure, and we outline how this workflow is applicable to a wider community, e.g. commercial and passenger shipping.
- Published
- 2022
7. Aspirin and Subarachnoid Haemorrhage in the UK Biobank
- Author
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Ewbank, Frederick, Birks, Jacqueline, Gaastra, Benjamin, Hall, Samuel, Galea, Ian, and Bulters, Diederik
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- 2023
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8. Self-interaction error induces spurious charge transfer artefacts in core-level simulations of x-ray photoemission and absorption spectroscopy of metal-organic interfaces
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Hall, Samuel J., Klein, Benedikt P., and Maurer, Reinhard J.
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Condensed Matter - Materials Science - Abstract
First principles simulation of x-ray photoemission spectroscopy (XPS) is an important tool in the challenging interpretation and assignment of XPS data of metal-organic interfaces. We investigate the origin of the disagreement between XPS simulation and experiment for the azulene molecule adsorbed on Ag(111). We systematically eliminate possible causes for this discrepancy, including errors in the structural model and finite size effects in periodic boundary conditions. By analysis of the electronic structure in the ground-state and the core-hole excited-state, we are able to trace the error back to artificial charge transfer between adsorbed molecule and metal surface. This is caused by the self-interaction error of common exchange-correlation functionals. This error is not remedied by standard hybrid or range-separated hybrid functionals. We employ an ad hoc self-interaction error correction based on molecular orbital projection, that exposes this issue and is able to recover the correct experimental behaviour. The charge transfer artefact also negatively affects the prediction of X-ray absorption spectra for this system. Both the simulated photoemisson and x-ray absorption spectra show a better agreement with experimental data, once the ad hoc correction is employed. Similar core-hole-induced charge artefacts may affect core-level simulations at metal-organic interfaces more generally., Comment: 9 pages, 4 figures
- Published
- 2021
9. Computational prediction of core-level spectroscopy of metal-organic interfaces to reveal chemical interactions, bonding and behaviours
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Hall, Samuel J.
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QD Chemistry - Abstract
Molecules adsorbed onto metal surfaces, especially carbon-based aromatic molecules, can provide systems that offer tunable properties and can be used in organic light-emitting diodes (OLEDs). It is important to understand the behaviour of these systems at a molecular level in order to rationally engineer interfaces with specific properties. Core-level spectroscopy can provide a beneficial method to probe aspects of molecule-metal interfaces such as geometrical structure, stability, chemical bonding and electronic structure. X-ray photoelectron spectroscopy (XPS) and near-edge absorption fine structure (NEXAFS) spectroscopy can be used in tandem to gain significant insight into the studied system. However, the resulting spectra from these techniques can often prove hard to fully analyse as they contain multiple close-lying features and loss of clarity from broadening. This is where simulations of spectra can come in to help to disentangle and interpret spectra. This thesis establishes practical simulation workflows to predict XPS and NEXAFS spectra of metal-organic interfaces based on Density Functional Theory (DFT). These methods are applied to study the adsorption of aromatic adsorbates on metal surfaces, two-dimensional networks, and an oxidised diamond surface. As part of this work, the assessment of the performance and accuracy of simulations against experiment was carried out. Core-level simulations on various systems were performed to rationalise experimental findings on structure, stability, and surface chemical bonding.
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- 2022
10. Follow-Up Follow-up of Arachnoid Cysts: Brain Plasticity Plasticity Following Surgery Surgery for Arachnoid Cysts
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Hall, Samuel, Gaastra, Benjamin, Tsitouras, Vassilios, Turgut, Mehmet, editor, Akhaddar, Ali, editor, Turgut, Ahmet T., editor, and Hall, Walter A., editor
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- 2023
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11. Exploring the Application of Peer-Assisted Learning in Practical Neuroanatomy Classes: A Cohort Comparison Within a Medical Curriculum
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De Louche, Calvin D., Hassan, Rifat, Laurayne, Hailey F., Wijeyendram, Papakas, Kurn, Octavia R., Woodward, James, Sbayeh, Amgad, Hall, Samuel, and Border, Scott
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- 2023
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12. Rapid cloud removal of dimethyl sulfide oxidation products limits SO2 and cloud condensation nuclei production in the marine atmosphere.
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Novak, Gordon A, Fite, Charles H, Holmes, Christopher D, Veres, Patrick R, Neuman, J Andrew, Faloona, Ian, Thornton, Joel A, Wolfe, Glenn M, Vermeuel, Michael P, Jernigan, Christopher M, Peischl, Jeff, Ryerson, Thomas B, Thompson, Chelsea R, Bourgeois, Ilann, Warneke, Carsten, Gkatzelis, Georgios I, Coggon, Mathew M, Sekimoto, Kanako, Bui, T Paul, Dean-Day, Jonathan, Diskin, Glenn S, DiGangi, Joshua P, Nowak, John B, Moore, Richard H, Wiggins, Elizabeth B, Winstead, Edward L, Robinson, Claire, Thornhill, K Lee, Sanchez, Kevin J, Hall, Samuel R, Ullmann, Kirk, Dollner, Maximilian, Weinzierl, Bernadett, Blake, Donald R, and Bertram, Timothy H
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cloud condensation nuclei ,cloud processing ,dimethyl sulfide ,marine sulfur ,sulfate aerosol ,Climate Action - Abstract
Oceans emit large quantities of dimethyl sulfide (DMS) to the marine atmosphere. The oxidation of DMS leads to the formation and growth of cloud condensation nuclei (CCN) with consequent effects on Earth's radiation balance and climate. The quantitative assessment of the impact of DMS emissions on CCN concentrations necessitates a detailed description of the oxidation of DMS in the presence of existing aerosol particles and clouds. In the unpolluted marine atmosphere, DMS is efficiently oxidized to hydroperoxymethyl thioformate (HPMTF), a stable intermediate in the chemical trajectory toward sulfur dioxide (SO2) and ultimately sulfate aerosol. Using direct airborne flux measurements, we demonstrate that the irreversible loss of HPMTF to clouds in the marine boundary layer determines the HPMTF lifetime (τHPMTF < 2 h) and terminates DMS oxidation to SO2 When accounting for HPMTF cloud loss in a global chemical transport model, we show that SO2 production from DMS is reduced by 35% globally and near-surface (0 to 3 km) SO2 concentrations over the ocean are lowered by 24%. This large, previously unconsidered loss process for volatile sulfur accelerates the timescale for the conversion of DMS to sulfate while limiting new particle formation in the marine atmosphere and changing the dynamics of aerosol growth. This loss process potentially reduces the spatial scale over which DMS emissions contribute to aerosol production and growth and weakens the link between DMS emission and marine CCN production with subsequent implications for cloud formation, radiative forcing, and climate.
- Published
- 2021
13. The Nuts and Bolts of Ab-Initio Core-Hole Simulations for K-shell X-Ray Photoemission and Absorption Spectra
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Klein, Benedikt, Hall, Samuel J., and Maurer, Reinhard J.
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Condensed Matter - Materials Science - Abstract
X-ray photoemission (XPS) and Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy play an important role in investigating the structure and electronic structure of materials and surfaces. Ab-initio simulations provide crucial support for the interpretation of complex spectra containing overlapping signatures. Approximate core-hole simulation methods based on Density Functional Theory such as the Delta-Self-Consistent-Field ($\Delta$SCF) method or the transition potential (TP) method are widely used to predict K-shell XPS and NEXAFS signatures of organic molecules, inorganic materials and metal-organic interfaces at reliable accuracy and affordable computational cost. We present the numerical and technical details of our variants of the $\Delta$SCF and transition potential method (coined $\Delta$IP-TP) to simulate XPS and NEXAFS transitions. Using exemplary molecules in gas-phase, in bulk crystals, and at metal-organic interfaces, we systematically assess how practical simulation choices affect the stability and accuracy of simulations. These include the choice of exchange-correlation functional, basis set, the method of core-hole localization, and the use of periodic boundary conditions. We particularly focus on the choice of aperiodic or periodic description of systems and how spurious charge effects in periodic calculations affect the simulation outcomes. For the benefit of practitioners in the field, we discuss sensible default choices, limitations of the methods, and future prospects., Comment: 52 pages
- Published
- 2020
14. Incidence and epidemiology of aneurysmal subarachnoid haemorrhage in Australian Aboriginal and Torres Strait Islanders; a ten-year population study
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Zheng, Amy, Su, Eunice, and Hall, Samuel
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- 2023
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15. A Multicentre Analysis of Approaches to Learning and Student Experiences of Learning Anatomy Online
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Stone, Danya, Longhurst, Georga J., Dulohery, Kate, Campbell, Thomas, Richards, Annalise, O’Brien, Dominic, Franchi, Thomas, Hall, Samuel, and Border, Scott
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- 2022
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16. Constraining remote oxidation capacity with ATom observations
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Travis, Katherine R, Heald, Colette L, Allen, Hannah M, Apel, Eric C, Arnold, Stephen R, Blake, Donald R, Brune, William H, Chen, Xin, Commane, Róisín, Crounse, John D, Daube, Bruce C, Diskin, Glenn S, Elkins, James W, Evans, Mathew J, Hall, Samuel R, Hintsa, Eric J, Hornbrook, Rebecca S, Kasibhatla, Prasad S, Kim, Michelle J, Luo, Gan, McKain, Kathryn, Millet, Dylan B, Moore, Fred L, Peischl, Jeffrey, Ryerson, Thomas B, Sherwen, Tomás, Thames, Alexander B, Ullmann, Kirk, Wang, Xuan, Wennberg, Paul O, Wolfe, Glenn M, and Yu, Fangqun
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Earth Sciences ,Atmospheric Sciences ,Climate Action ,Astronomical and Space Sciences ,Meteorology & Atmospheric Sciences ,Atmospheric sciences ,Climate change science - Abstract
The global oxidation capacity, defined as the tropospheric mean concentration of the hydroxyl radical (OH), controls the lifetime of reactive trace gases in the atmosphere such as methane and carbon monoxide (CO). Models tend to underestimate the methane lifetime and CO concentrations throughout the troposphere, which is consistent with excessive OH. Approximately half of the oxidation of methane and non-methane volatile organic compounds (VOCs) is thought to occur over the oceans where oxidant chemistry has received little validation due to a lack of observational constraints. We use observations from the first two deployments of the NASA ATom aircraft campaign during July-August 2016 and January-February 2017 to evaluate the oxidation capacity over the remote oceans and its representation by the GEOS-Chem chemical transport model. The model successfully simulates the magnitude and vertical profile of remote OH within the measurement uncertainties. Comparisons against the drivers of OH production (water vapor, ozone, and NO y concentrations, ozone photolysis frequencies) also show minimal bias, with the exception of wintertime NO y . The severe model overestimate of NO y during this period may indicate insufficient wet scavenging and/or missing loss on sea-salt aerosols. Large uncertainties in these processes require further study to improve simulated NO y partitioning and removal in the troposphere, but preliminary tests suggest that their overall impact could marginally reduce the model bias in tropospheric OH. During the ATom-1 deployment, OH reactivity (OHR) below 3 km is significantly enhanced, and this is not captured by the sum of its measured components (cOHRobs) or by the model (cOHRmod). This enhancement could suggest missing reactive VOCs but cannot be explained by a comprehensive simulation of both biotic and abiotic ocean sources of VOCs. Additional sources of VOC reactivity in this region are difficult to reconcile with the full suite of ATom measurement constraints. The model generally reproduces the magnitude and seasonality of cOHRobs but underestimates the contribution of oxygenated VOCs, mainly acetaldehyde, which is severely underestimated throughout the troposphere despite its calculated lifetime of less than a day. Missing model acetaldehyde in previous studies was attributed to measurement uncertainties that have been largely resolved. Observations of peroxyacetic acid (PAA) provide new support for remote levels of acetaldehyde. The underestimate in both model acetaldehyde and PAA is present throughout the year in both hemispheres and peaks during Northern Hemisphere summer. The addition of ocean sources of VOCs in the model increases cOHRmod by 3% to 9% and improves model-measurement agreement for acetaldehyde, particularly in winter, but cannot resolve the model summertime bias. Doing so would require 100 Tg yr-1 of a long-lived unknown precursor throughout the year with significant additional emissions in the Northern Hemisphere summer. Improving the model bias for remote acetaldehyde and PAA is unlikely to fully resolve previously reported model global biases in OH and methane lifetime, suggesting that future work should examine the sources and sinks of OH over land.
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- 2020
17. Observation-based modeling of ozone chemistry in the Seoul metropolitan area during the Korea-United States Air Quality Study (KORUS-AQ)
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Schroeder, Jason R, Crawford, James H, Ahn, Joon-Young, Chang, Limseok, Fried, Alan, Walega, James, Weinheimer, Andrew, Montzka, Denise D, Hall, Samuel R, Ullmann, Kirk, Wisthaler, Armin, Mikoviny, Tomas, Chen, Gao, Blake, Donald R, Blake, Nicola J, Hughes, Stacey C, Meinardi, Simone, Diskin, Glenn, Digangi, Joshua P, Choi, Yonghoon, Pusede, Sally E, Huey, Greg L, Tanner, David J, Kim, Michelle, and Wennberg, Paul
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Ozone ,Air quality ,Photochemistry ,Korea ,Seoul - Abstract
The Seoul Metropolitan Area (SMA) has a population of 24 million and frequently experiences unhealthy levels of ozone (O3). In this work, measurements taken during the Korea-United States Air Quality Study (KORUS-AQ, 2016) are used to explore regional gradients in O3 and its chemical precursors, and an observationally-constrained 0-D photochemical box model is used to quantify key aspects of O3 production including its sensitivity to precursor gases. Box model performance was evaluated by comparing modeled concentrations of select secondary species to airborne measurements. These comparisons indicate that the steady state assumption used in 0-D box models cannot describe select intermediate species, highlighting the importance of having a broad suite of trace gases as model constraints. When fully constrained, aggregated statistics of modeled O3 production rates agreed with observed changes in O3, indicating that the box model was able to represent the majority of O3 chemistry. Comparison of airborne observations between urban Seoul and a downwind receptor site reveal a positive gradient in O3 coinciding with a negative gradient in NOx, no gradient in CH2O, and a slight positive gradient in modeled rates of O3 production. Together, these observations indicate a radical-limited (VOC-limited) O3 production environment in the SMA. Zero-out simulations identified C7+ aromatics as the dominant VOC contributors to O3 production, with isoprene and anthropogenic alkenes making smaller but appreciable contributions. Simulations of model sensitivity to decreases in NOx produced results that were not spatially uniform, with large increases in O3 production predicted for urban Seoul and decreases in O3 production predicted for far-outlying areas. The policy implications of this work are clear: Effective O3 mitigation strategies in the SMA must focus on reducing local emissions of C7+ aromatics, while reductions in NOx emissions may increase O3 in some areas but generally decrease the regional extent of O3 exposure.
- Published
- 2020
18. Investigating the impact of remote neuroanatomy education during the COVID‐19 pandemic using online examination performance in a National Undergraduate Neuroanatomy Competition
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De Louche, Calvin D., primary, Taylor, Charles, additional, Weiss, Veronique B. N., additional, Amendra, Damian, additional, Philp, Janet, additional, Parrott, Rachel, additional, Hall, Samuel, additional, and Border, Scott, additional
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- 2024
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19. Supplementary material to "Using observed urban NOx sinks to constrain VOC reactivity and the ozone and radical budget in the Seoul Metropolitan Area"
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Nault, Benjamin A., primary, Travis, Katherine R., additional, Crawford, James H., additional, Blake, Donald R., additional, Campuzano-Jost, Pedro, additional, Cohen, Ronald C., additional, DiGangi, Joshua P., additional, Diskin, Glenn S., additional, Hall, Samuel R., additional, Huey, L. Gregory, additional, Jimenez, Jose L., additional, Kim, Kyung-Eun, additional, Lee, Young R., additional, Simpson, Isobel J., additional, Ullmann, Kirk, additional, and Wisthaler, Armin, additional
- Published
- 2024
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20. Using observed urban NOx sinks to constrain VOC reactivity and the ozone and radical budget in the Seoul Metropolitan Area
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Nault, Benjamin A., primary, Travis, Katherine R., additional, Crawford, James H., additional, Blake, Donald R., additional, Campuzano-Jost, Pedro, additional, Cohen, Ronald C., additional, DiGangi, Joshua P., additional, Diskin, Glenn S., additional, Hall, Samuel R., additional, Huey, L. Gregory, additional, Jimenez, Jose L., additional, Kim, Kyung-Eun, additional, Lee, Young R., additional, Simpson, Isobel J., additional, Ullmann, Kirk, additional, and Wisthaler, Armin, additional
- Published
- 2024
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21. Probing isoprene photochemistry at atmospherically relevant nitric oxide levels
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Zhang, Xuan, Wang, Siyuan, Apel, Eric C., Schwantes, Rebecca H., Hornbrook, Rebecca S., Hills, Alan J., DeMarsh, Kate E., Moo, Zeyi, Ortega, John, Brune, William H., Mauldin, Roy L., III, Cantrell, Christopher A., Teng, Alexander P., Blake, Donald R., Campos, Teresa, Daube, Bruce, Emmons, Louisa K., Hall, Samuel R., Ullmann, Kirk, Wofsy, Steven C., Wennberg, Paul O., Tyndall, Geoffrey S., and Orlando, John J.
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- 2022
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22. Multiple-Choice versus Open-Ended Questions in Advanced Clinical Neuroanatomy: Using a National Neuroanatomy Assessment to Investigate Variability in Performance Using Different Question Types
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Merzougui, Wassim H., Myers, Matthew A., Hall, Samuel, Elmansouri, Ahmad, Parker, Rob, Robson, Alistair D., Kurn, Octavia, Parrott, Rachel, Geoghegan, Kate, Harrison, Charlotte H., Anbu, Deepika, Dean, Oliver, and Border, Scott
- Abstract
Methods of assessment in anatomy vary across medical schools in the United Kingdom (UK) and beyond; common methods include written, spotter, and oral assessment. However, there is limited research evaluating these methods in regards to student performance and perception. The National Undergraduate Neuroanatomy Competition (NUNC) is held annually for medical students throughout the UK. Prior to 2017, the competition asked open-ended questions (OEQ) in the anatomy spotter examination, and in subsequent years also asked single best answer (SBA) questions. The aim of this study is to assess medical students' performance on, and perception of, SBA and OEQ methods of assessment in a spotter style anatomy examination. Student examination performance was compared between OEQ (2013-2016) and SBA (2017-2020) for overall score and each neuroanatomical subtopic. Additionally, a questionnaire explored students' perceptions of SBAs. A total of 631 students attended the NUNC in the studied period. The average mark was significantly higher in SBAs compared to OEQs (60.6% vs. 43.1%, P < 0.0001)--this was true for all neuroanatomical subtopics except the cerebellum. Students felt that they performed better on SBA than OEQs, and diencephalon was felt to be the most difficult neuroanatomical subtopic (n = 38, 34.8%). Students perceived SBA questions to be easier than OEQs and performed significantly better on them in a neuroanatomical spotter examination. Further work is needed to ascertain whether this result is replicable throughout anatomy education.
- Published
- 2021
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23. Working in Creative Partnership with Students to Co-Produce Neuroanatomy E-Learning Resources in a New Era of Blended Learning
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Border, Scott, Woodward, Charlotte, Kurn, Octavia, Birchall, Cara, Laurayne, Hailey, Anbu, Deepika, Taylor, Charlie, and Hall, Samuel
- Abstract
Anatomists are well placed to tackle the transition from face-to-face to blended learning approaches as a result of the rapidly forced changes brought about by COVID-19. The subject is extremely visual and has, therefore, previously been a target for the development of technology-enhanced learning initiatives over the last ten years. Today's students have come to expect the integration of technology in the classroom and remotely. They adjust quickly to the innovative use of new applications and software and have begun to integrate it within their own workflow for note taking and study aids. Given the intense drive toward blended deliveries of anatomy as a result of the COVID-19 pandemic, it is easy to picture how the benefits of working in partnership with students (in order to achieve many of these aims) would be possible, particularly in difficult subjects like neuroanatomy. In doing so, it provides anatomists with new opportunities to engage students in a way that aligns well with best practice frameworks for engaging students through partnership. The current United Kingdom guidelines set out by Advance HE (a professional membership organization for promoting excellence in higher education) strongly encourages the higher education community to seek out appropriate academic contexts where a balance of power can be struck between staff and student to create a community of practice. If such an approach can be fully embraced by anatomists, a strong argument can be made for seizing the opportunity to optimize the benefits of student partnership work in this discipline.
- Published
- 2021
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24. Atmospheric Acetaldehyde: Importance of Air‐Sea Exchange and a Missing Source in the Remote Troposphere
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Wang, Siyuan, Hornbrook, Rebecca S, Hills, Alan, Emmons, Louisa K, Tilmes, Simone, Lamarque, Jean‐François, Jimenez, Jose L, Campuzano‐Jost, Pedro, Nault, Benjamin A, Crounse, John D, Wennberg, Paul O, Kim, Michelle, Allen, Hannah, Ryerson, Thomas B, Thompson, Chelsea R, Peischl, Jeff, Moore, Fred, Nance, David, Hall, Brad, Elkins, James, Tanner, David, Huey, L Gregory, Hall, Samuel R, Ullmann, Kirk, Orlando, John J, Tyndall, Geoff S, Flocke, Frank M, Ray, Eric, Hanisco, Thomas F, Wolfe, Glenn M, St. Clair, Jason, Commane, Róisín, Daube, Bruce, Barletta, Barbara, Blake, Donald R, Weinzierl, Bernadett, Dollner, Maximilian, Conley, Andrew, Vitt, Francis, Wofsy, Steven C, Riemer, Daniel D, and Apel, Eric C
- Subjects
Climate Action ,Meteorology & Atmospheric Sciences - Abstract
We report airborne measurements of acetaldehyde (CH3CHO) during the first and second deployments of the National Aeronautics and Space Administration (NASA) Atmospheric Tomography Mission (ATom). The budget of CH3CHO is examined using the Community Atmospheric Model with chemistry (CAM-chem), with a newly-developed online air-sea exchange module. The upper limit of the global ocean net emission of CH3CHO is estimated to be 34 Tg a-1 (42 Tg a-1 if considering bubble-mediated transfer), and the ocean impacts on tropospheric CH3CHO are mostly confined to the marine boundary layer. Our analysis suggests that there is an unaccounted CH3CHO source in the remote troposphere and that organic aerosols can only provide a fraction of this missing source. We propose that peroxyacetic acid (PAA) is an ideal indicator of the rapid CH3CHO production in the remote troposphere. The higher-than-expected CH3CHO measurements represent a missing sink of hydroxyl radicals (and halogen radical) in current chemistry-climate models.
- Published
- 2019
25. Integration of airborne and ground observations of nitryl chloride in the Seoul metropolitan area and the implications on regional oxidation capacity during KORUS-AQ 2016
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Jeong, Daun, Seco, Roger, Gu, Dasa, Lee, Youngro, Nault, Benjamin A, Knote, Christoph J, Mcgee, Tom, Sullivan, John T, Jimenez, Jose L, Campuzano-Jost, Pedro, Blake, Donald R, Sanchez, Dianne, Guenther, Alex B, Tanner, David, Huey, L Gregory, Long, Russell, Anderson, Bruce E, Hall, Samuel R, Ullmann, Kirk, Shin, Hye-jung, Herndon, Scott C, Lee, Youngjae, Kim, Danbi, Ahn, Joonyoung, and Kim, Saewung
- Subjects
Astronomical and Space Sciences ,Atmospheric Sciences ,Meteorology & Atmospheric Sciences - Abstract
Nitryl chloride (ClNO2) is a radical reservoir species that releases chlorine radicals upon photolysis. An integrated analysis of the impact of ClNO2 on regional photochemistry in the Seoul metropolitan area (SMA) during the Korea-United States Air Quality Study (KORUS-AQ) 2016 field campaign is presented. Comprehensive multiplatform observations were conducted aboard the NASA DC-8 and at two ground sites (Olympic Park, OP; Taehwa Research Forest, TRF), representing an urbanized area and a forested suburban region, respectively. Positive correlations between daytime Cl2 and ClNO2 were observed at both sites, the slope of which was dependent on O3 levels. The possible mechanisms are explored through box model simulations constrained with observations. The overall diurnal variations in ClNO2 at both sites appeared similar but the nighttime variations were systematically different. For about half of the observation days at the OP site the level of ClNO2 increased at sunset but rapidly decreased at around midnight. On the other hand, high levels were observed throughout the night at the TRF site. Significant levels of ClNO2 were observed at both sites for 4-5 h after sunrise. Airborne observations, box model calculations, and back-trajectory analysis consistently show that these high levels of ClNO2 in the morning are likely from vertical or horizontal transport of air masses from the west. Box model results show that chlorine-radical-initiated chemistry can impact the regional photochemistry by elevating net chemical production rates of ozone by 25% in the morning.
- Published
- 2019
26. Integration of Airborne and Ground Observations of Nitryl Chloride in the Seoul Metropolitan Area and the Implications on Regional Oxidation Capacity During KORUS-AQ 2016
- Author
-
Jeong, Daun, Seco, Roger, Gu, Dasa, Lee, Youngro, Nault, Benjamin A, Knote, Christoph J, Mcgee, Tom, Sullivan, John T, Jimenez, Jose L, Campuzano-Jost, Pedro, Blake, Donald R, Sanchez, Dianne, Guenther, Alex B, Tanner, David, Huey, L Gregory, Long, Russell, Anderson, Bruce E, Hall, Samuel R, Ullmann, Kirk, Shin, Hye-Jung, Herndon, Scott C, Lee, Youngjae, Kim, Danbi, Ahn, Joonyoung, and Kim, Saewung
- Abstract
Abstract. Nitryl chloride (ClNO2) is a radical reservoir species that releases chlorine radicals upon photolysis. An integrated analysis of the impact of ClNO2 on regional photochemistry in the Seoul Metropolitan Area (SMA) during the Korean-United States-Air Quality (KORUS-AQ) 2016 field campaign is presented. Comprehensive multiplatform observations were conducted aboard the NASA DC-8 and at two ground sites (Olympic Park, OP; Taehwa Research Forest, TRF), representing an urbanized area and a forested region downwind, respectively. The overall diurnal variations of ClNO2 in both sites appeared similar but the night time variation were systematically different. For about half of the observation days at the OP site the level of ClNO2 increased at sunset but rapidly decreased at around midnight. On the other hand, high levels were sustained throughout the night at the TRF site. Significant levels of ClNO2 were sustained at both sites for 4–5 hours after sunrise. Airborne observations, box model calculations, and back trajectory analysis consistently show that this high levels of ClNO2 in the morning is likely due to the transport of air masses within the boundary layer. Box model results show that chlorine radical initiated chemistry can impact the regional photochemistry by elevating net ozone production rate up to ~ 25 % in the morning.
- Published
- 2018
27. Hepatitis B and pregnancy: understanding the experiences of care among pregnant women and recent mothers in metropolitan Melbourne
- Author
-
Ahad, Marvad, Wallace, Jack, Xiao, Yinzong, van Gemert, Caroline, Bennett, Gabrielle, Darby, Jonathan, Desmond, Paul, Hall, Samuel, Holmes, Jacinta, Papaluca, Tim, Glasgow, Susanne, Thompson, Alexander, Hellard, Margaret, Doyle, Joseph, and Howell, Jessica
- Published
- 2022
- Full Text
- View/download PDF
28. Coexistence of carbonyl and ether groups on oxygen-terminated (110)-oriented diamond surfaces
- Author
-
Chaudhuri, Shayantan, Hall, Samuel J., Klein, Benedikt P., Walker, Marc, Logsdail, Andrew J., Macpherson, Julie V., and Maurer, Reinhard J.
- Published
- 2022
- Full Text
- View/download PDF
29. Evaluating the Efficacy and Optimisation of the Peer-Led Flipped Model Using TEL Resources Within Neuroanatomy
- Author
-
Anbu, Deepika, Robson, Alistair, Kurn, Octavia, Taylor, Charles, Dean, Oliver, Payne, December, Nagy, Eva, Harrison, Charlotte, Hall, Samuel, Border, Scott, Crusio, Wim E., Series Editor, Dong, Haidong, Series Editor, Radeke, Heinfried H., Series Editor, Rezaei, Nima, Series Editor, Steinlein, Ortrud, Series Editor, Xiao, Junjie, Series Editor, and Rea, Paul M., editor
- Published
- 2021
- Full Text
- View/download PDF
30. Observations of atmospheric oxidation and ozone production in South Korea
- Author
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Brune, William H., Miller, David O., Thames, Alexander B., Brosius, Alexandra L., Barletta, Barbara, Blake, Donald R., Blake, Nicola J., Chen, Gao, Choi, Yonghoon, Crawford, James H., Digangi, Joshua P., Diskin, Glenn, Fried, Alan, Hall, Samuel R., Hanisco, Thomas F., Huey, Greg L., Hughes, Stacey C., Kim, Michelle, Meinardi, Simone, Montzka, Denise D., Pusede, Sally E., Schroeder, Jason R., Teng, Alex, Tanner, David J., Ullmann, Kirk, Walega, James, Weinheimer, Andrew, Wisthaler, Armin, and Wennberg, Paul O.
- Published
- 2022
- Full Text
- View/download PDF
31. Using observed urban NOx sinks to constrain VOC reactivity and the ozone and radical budget in the Seoul Metropolitan Area.
- Author
-
Nault, Benjamin A., Travis, Katherine R., Crawford, James H., Blake, Donald R., Campuzano-Jost, Pedro, Cohen, Ronald C., DiGangi, Joshua P., Diskin, Glenn S., Hall, Samuel R., Huey, L. Gregory, Jimenez, Jose L., Kim, Kyung-Eun, Lee, Young Ro, Simpson, Isobel J., Ullmann, Kirk, and Wisthaler, Armin
- Subjects
ENVIRONMENTAL research ,RADICALS (Chemistry) ,METROPOLITAN areas ,AIR quality ,VOLATILE organic compounds - Abstract
Ozone (O3) is an important secondary pollutant that impacts air quality and human health. Eastern Asia has high regional O3 background due to the numerous sources and increasing and rapid industrial growth, which also impacts the Seoul Metropolitan Area (SMA). However, the SMA has also been experiencing increasing O3 driven by decreasing NOx emissions, highlighting the role of the local in situ O3 production on the SMA. Here, comprehensive gas-phase measurements collected on the NASA DC-8 during the National Institute of Environmental Research (NIER)/NASA Korea–United States Air Quality (KORUS-AQ) study are used to constrain the instantaneous O3 production rate over the SMA. The observed NOx oxidized products support the importance of non-measured peroxy nitrates (PNs) in the O3 chemistry in the SMA, as they accounted for ∼49 % of the total PNs. Using the total measured PNs (Σ PNs) and alkyl and multifunctional nitrates (Σ ANs), unmeasured volatile organic compound (VOC) reactivity (R(VOC)) is constrained and found to range from 1.4–2.1 s-1. Combining the observationally constrained R(VOC) with the other measurements on the DC-8, the instantaneous net O3 production rate, which is as high as ∼10 ppbvh-1 , along with the important sinks of O3 and radical chemistry, is constrained. This analysis shows that Σ PNs play an important role in both the sinks of O3 and radical chemistry. Since Σ PNs are assumed to be in a steady state, the results here highlight the role that Σ PNs play in urban environments in altering the net O3 production, but Σ PNs can potentially lead to increased net O3 production downwind due to their short lifetime (∼1 h). The results provide guidance for future measurements to identify the missing R(VOCs) and Σ PN production. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
32. Impact of improved representation of volatile organic compound emissions and production of NOx reservoirs on modeled urban ozone production.
- Author
-
Travis, Katherine R., Nault, Benjamin A., Crawford, James H., Bates, Kelvin H., Blake, Donald R., Cohen, Ronald C., Fried, Alan, Hall, Samuel R., Huey, L. Gregory, Lee, Young Ro, Meinardi, Simone, Min, Kyung-Eun, Simpson, Isobel J., and Ullman, Kirk
- Subjects
ENVIRONMENTAL research ,PEROXYACETYL nitrate ,LIQUEFIED petroleum gas ,VOLATILE organic compounds ,CHEMICAL models ,ACETALDEHYDE ,EMISSION inventories - Abstract
The fraction of urban volatile organic compound (VOC) emissions attributable to fossil fuel combustion has been declining in many parts of the world, resulting in a need to better constrain other anthropogenic sources of these emissions. During the National Institute of Environmental Research (NIER) and National Aeronautics and Space Administration (NASA) Korea-United States Air Quality (KORUS-AQ) field study in Seoul, South Korea, during May–June 2016, air quality models underestimated ozone, formaldehyde, and peroxyacetyl nitrate (PAN), indicating an underestimate of VOCs in the emissions inventory. Here, we use aircraft observations interpreted with the GEOS-Chem chemical transport model (version 13.4.0) to assess the need for increases in VOC emissions and for a revised chemical mechanism to improve treatment of VOC speciation and chemistry. We find that the largest needed VOC emissions increases are attributable to compounds associated with volatile chemical products, liquefied petroleum gas (LPG) and natural gas emissions, and long-range transport. Revising model chemistry to better match observed VOC speciation together with increasing model emissions of underestimated VOC species increased calculated OH reactivity by + 2 s -1 and ozone production by + 2 ppb h -1. Ozone increased by + 6 ppb below 2 km and + 9 ppb at the surface, and formaldehyde and acetaldehyde increased by + 30 % and + 120 % aloft, respectively, all in better agreement with observations. The larger increase in acetaldehyde was attributed to ethanol emissions, which we found to be as important for ozone production as isoprene or alkenes. The increased acetaldehyde significantly reduced the model PAN bias. The need for additional unmeasured VOCs, however, was indicated by a remaining model bias of - 0.8 ppb in formaldehyde and a - 57 % and - 52 % underestimate in higher peroxynitrates (PNs) and alkyl nitrates (ANs), respectively. We added additional chemistry to the model to represent an additional six PNs from observed VOCs but were unable to account for the majority of missing PNs. However, four of these PNs were modeled at concentrations similar to other commonly measured PNs (> 2 % of PAN) indicating that these should be measured in future campaigns and considered from other VOC emission sources (e.g., fires). We hypothesize that emissions of oxygenated VOCs (OVOCs) such as ≥ C5 aldehydes from cooking and/or alkenes associated with volatile chemical products could produce both PNs and ANs and improve remaining model biases. Emerging research on the emissions and chemistry of these species will soon allow for modeling of their impact on local and regional photochemistry. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
33. Stratospheric air intrusions promote global-scale new particle formation.
- Author
-
Jiaoshi Zhang, Xianda Gong, Crosbie, Ewan, Diskin, Glenn, Froyd, Karl, Hall, Samuel, Kupc, Agnieszka, Moore, Richard, Peischl, Jeff, Rollins, Andrew, Schwarz, Joshua, Shook, Michael, Thompson, Chelsea, Ullmann, Kirk, Williamson, Christina, Wisthaler, Armin, Lu Xu, Ziemba, Luke, Brock, Charles A., and Jian Wang
- Published
- 2024
- Full Text
- View/download PDF
34. Quantification of organic aerosol and brown carbon evolution in fresh wildfire plumes
- Author
-
Palm, Brett B., Peng, Qiaoyun, Fredrickson, Carley D., Lee, Ben H., Garofalo, Lauren A., Pothier, Matson A., Kreidenweis, Sonia M., Farmer, Delphine K., Pokhrel, Rudra P., Shen, Yingjie, Murphy, Shane M., Permar, Wade, Hu, Lu, Campos, Teresa L., Hall, Samuel R., Ullmann, Kirk, Zhang, Xuan, Flocke, Frank, Fischer, Emily V., and Thornton, Joel A.
- Published
- 2020
35. Introduction of the Modified Neuroanatomy Motivation Questionnaire and Its Role in Comparing Medical Student Attitudes Towards Learning Neuroanatomy Between Neuro-enthusiasts and Standard Students
- Author
-
Hall, Samuel, Kurn, Octavia, Anbu, Deepika, Nagy, Eva, Dean, Oliver, Robson, Alistair, Taylor, Charles, Elmansouri, Ahmad, Geoghegan, Kate, Payne, December, Myers, Matthew, Stephens, Jonny, Merzougui, Wassim, and Border, Scott
- Published
- 2021
- Full Text
- View/download PDF
36. Atmospheric oxidation in the presence of clouds during the Deep Convective Clouds and Chemistry (DC3) study
- Author
-
Brune, William H, Ren, Xinrong, Zhang, Li, Mao, Jingqiu, Miller, David O, Anderson, Bruce E, Blake, Donald R, Cohen, Ronald C, Diskin, Glenn S, Hall, Samuel R, Hanisco, Thomas F, Huey, L Gregory, Nault, Benjamin A, Peischl, Jeff, Pollack, Ilana, Ryerson, Thomas B, Shingler, Taylor, Sorooshian, Armin, Ullmann, Kirk, Wisthaler, Armin, and Wooldridge, Paul J
- Subjects
Earth Sciences ,Atmospheric Sciences ,Astronomical and Space Sciences ,Meteorology & Atmospheric Sciences ,Atmospheric sciences ,Climate change science - Abstract
Deep convective clouds are critically important to the distribution of atmospheric constituents throughout the troposphere but are difficult environments to study. The Deep Convective Clouds and Chemistry (DC3) study in 2012 provided the environment, platforms, and instrumentation to test oxidation chemistry around deep convective clouds and their impacts downwind. Measurements on the NASA DC-8 aircraft included those of the radicals hydroxyl (OH) and hydroperoxyl (HO2), OH reactivity, and more than 100 other chemical species and atmospheric properties. OH, HO2, and OH reactivity were compared to photochemical models, some with and some without simplified heterogeneous chemistry, to test the understanding of atmospheric oxidation as encoded in the model. In general, the agreement between the observed and modeled OH, HO2, and OH reactivity was within the combined uncertainties for the model without heterogeneous chemistry and the model including heterogeneous chemistry with small OH and HO2 uptake consistent with laboratory studies. This agreement is generally independent of the altitude, ozone photolysis rate, nitric oxide and ozone abundances, modeled OH reactivity, and aerosol and ice surface area. For a sunrise to midday flight downwind of a nighttime mesoscale convective system, the observed ozone increase is consistent with the calculated ozone production rate. Even with some observed-to-modeled discrepancies, these results provide evidence that a current measurement-constrained photochemical model can simulate observed atmospheric oxidation processes to within combined uncertainties, even around convective clouds. For this DC3 study, reduction in the combined uncertainties would be needed to confidently unmask errors or omissions in the model chemical mechanism.
- Published
- 2018
37. Cloud impacts on photochemistry: building a climatology of photolysis rates from the Atmospheric Tomography mission
- Author
-
Hall, Samuel R, Ullmann, Kirk, Prather, Michael J, Flynn, Clare M, Murray, Lee T, Fiore, Arlene M, Correa, Gustavo, Strode, Sarah A, Steenrod, Stephen D, Lamarque, Jean-Francois, Guth, Jonathan, Josse, Béatrice, Flemming, Johannes, Huijnen, Vincent, Abraham, N Luke, and Archibald, Alex T
- Subjects
Earth Sciences ,Atmospheric Sciences ,Climate Action ,Astronomical and Space Sciences ,Meteorology & Atmospheric Sciences ,Atmospheric sciences ,Climate change science - Abstract
Measurements from actinic flux spectroradiometers on board the NASA DC-8 during the Atmospheric Tomography (ATom) mission provide an extensive set of statistics on how clouds alter photolysis rates (J values) throughout the remote Pacific and Atlantic Ocean basins. J values control tropospheric ozone and methane abundances, and thus clouds have been included for more than three decades in tropospheric chemistry modeling. ATom made four profiling circumnavigations of the troposphere capturing each of the seasons during 2016-2018. This work examines J values from the Pacific Ocean flights of the first deployment, but publishes the complete Atom-1 data set (29 July to 23 August 2016). We compare the observed J values (every 3s along flight track) with those calculated by nine global chemistry-climate/transport models (globally gridded, hourly, for a mid-August day). To compare these disparate data sets, we build a commensurate statistical picture of the impact of clouds on J values using the ratio of J-cloudy (standard, sometimes cloudy conditions) to J-clear (artificially cleared of clouds). The range of modeled cloud effects is inconsistently large but they fall into two distinct classes: (1) models with large cloud effects showing mostly enhanced J values aloft and or diminished at the surface and (2) models with small effects having nearly clear-sky J values much of the time. The ATom-1 measurements generally favor large cloud effects but are not precise or robust enough to point out the best cloud-modeling approach. The models here have resolutions of 50-200 km and thus reduce the occurrence of clear sky when averaging over grid cells. In situ measurements also average scattered sunlight over a mixed cloud field, but only out to scales of tens of kilometers. A primary uncertainty remains in the role of clouds in chemistry, in particular, how models average over cloud fields, and how such averages can simulate measurements.
- Published
- 2018
38. Observations of cyanogen bromide (BrCN) in the global troposphere and their relation to polar surface O3 destruction
- Author
-
Roberts, James M., primary, Wang, Siyuan, additional, Veres, Patrick R., additional, Neuman, J. Andrew, additional, Robinson, Michael A., additional, Bourgeois, Ilann, additional, Peischl, Jeff, additional, Ryerson, Thomas B., additional, Thompson, Chelsea R., additional, Allen, Hannah M., additional, Crounse, John D., additional, Wennberg, Paul O., additional, Hall, Samuel R., additional, Ullmann, Kirk, additional, Meinardi, Simone, additional, Simpson, Isobel J., additional, and Blake, Donald, additional
- Published
- 2024
- Full Text
- View/download PDF
39. Dural arteriovenous fistulas are not observed to convert to a higher grade after partial embolization
- Author
-
Walker, Erin, primary, Srienc, Anja, additional, Lew, Daphne, additional, Guniganti, Ridhima, additional, Lanzino, Giuseppe, additional, Brinjikji, Waleed, additional, Hayakawa, Minako, additional, Samaniego, Edgar A., additional, Derdeyn, Colin P., additional, Du, Rose, additional, Lai, Rosalind, additional, Sheehan, Jason P., additional, Starke, Robert M., additional, Abla, Adib, additional, Abdelsalam, Ahmed, additional, Gross, Bradley, additional, Albuquerque, Felipe, additional, Lawton, Michael T., additional, Kim, Louis J., additional, Levitt, Michael, additional, Amin-Hanjani, Sepideh, additional, Alaraj, Ali, additional, Winkler, Ethan, additional, Fox, W. Christopher, additional, Polifka, Adam, additional, Hall, Samuel, additional, Bulters, Diederik, additional, Durnford, Andrew, additional, Satomi, Junichiro, additional, Tada, Yoshiteru, additional, van Dijk, J. Marc C., additional, Potgieser, Adriaan R. E., additional, Chen, Ching-Jen, additional, Becerril-Gaitan, Andrea, additional, Osbun, Joshua W., additional, and Zipfel, Gregory J., additional
- Published
- 2024
- Full Text
- View/download PDF
40. TEL Methods Used for the Learning of Clinical Neuroanatomy
- Author
-
Elmansouri, Ahmad, Murray, Olivia, Hall, Samuel, Border, Scott, Crusio, Wim E., Series Editor, Dong, Haidong, Series Editor, Radeke, Heinfried H., Series Editor, Rezaei, Nima, Series Editor, Xiao, Junjie, Series Editor, and Rea, Paul M., editor
- Published
- 2020
- Full Text
- View/download PDF
41. Quantitative detection of iodine in the stratosphere
- Author
-
Koenig, Theodore K., Baidar, Sunil, Campuzano-Jost, Pedro, Cuevas, Carlos A., Dix, Barbara, Fernandez, Rafael P., Guo, Hongyu, Hall, Samuel R., Kinnison, Douglas, Nault, Benjamin A., Ullmann, Kirk, Jimenez, Jose L., Saiz-Lopez, Alfonso, and Volkamer, Rainer
- Published
- 2020
42. Paste extrusion 3D printing and characterization of lead zirconate titanate piezoelectric ceramics
- Author
-
Hall, Samuel E., Regis, Jaime E., Renteria, Anabel, Chavez, Luis A., Delfin, Luis, Vargas, Sebastian, Haberman, Michael R., Espalin, David, Wicker, Ryan, and Lin, Yirong
- Published
- 2021
- Full Text
- View/download PDF
43. Spinal Fractures Incurred by Sports-Related Injuries
- Author
-
Myers, Matthew Alex, Hall, Samuel, Wright, Andrew, Dare, Christopher, Griffith, Colin, Shenouda, Emad, Nader-Sepahi, Ali, and Sadek, Ahmed-Ramadan
- Published
- 2021
- Full Text
- View/download PDF
44. Le Fanu and Maturin : Two Reminiscences
- Author
-
Hall, Samuel Carter
- Published
- 2019
45. Awake craniotomy for tumour resection: The safety and feasibility of a simple technique
- Author
-
Hall, Samuel, Kabwama, Silvester, Sadek, Ahmed-Ramadan, Dando, Alexander, Roach, Joy, Weidmann, Crispin, and Grundy, Paul
- Published
- 2021
- Full Text
- View/download PDF
46. Paediatric spinal trauma presenting to a UK major trauma centre
- Author
-
Booker, James, Hall, Samuel, Dando, Alexander, Dare, Christopher, Davies, Evan, McGillion, Stephen, Mathad, Nijaguna, Waters, Ryan, Tsitouras, Vassilios, Mundil, Nilesh, Wahab, Salima, and Chakraborty, Aabir
- Published
- 2021
- Full Text
- View/download PDF
47. The Efficacy of Frontline Near-Peer Teaching in a Modern Medical Curriculum
- Author
-
Harrison, Charlotte H., Elmansouri, Ahmad, Parton, William, Myers, Matthew A., Hall, Samuel, Stephens, Jonny R., Seaby, Eleanor G., and Border, Scott
- Abstract
Within medical education a reduction in curriculum time for subjects, such as anatomy puts pressure on educators to ensure the same learning outcomes are conveyed in less time. This has the potential to impact negatively on student experience. Near-peer teaching (NPT) is often praised as an effective revision tool, but its use as a frontline teaching resource remains unreported. The study explores the potential for NPT to promote delivery of learning outcomes and maximize student experience within a neuroanatomy module for second year medical students. The study occurred in three educational settings, (1) frontline NPT of cranial nerves, (2) revision session NPT of cranial nerves, and (3) NPT alongside faculty staff in laboratory-based neuroanatomy practical exercises. For the first and second components, knowledge was measured using a pre- and post-session test and student perception was ascertained with a questionnaire. For the third component, student perception was assessed with an end-of-module survey. The results show that overall, NPT was well received by learners. A significant knowledge gain was seen between the pre- and post-session test of the frontline NPT session. The study presents evidence in favor of using NPTs to supplement the delivery of learning outcomes in a time and resource constrained curriculum. In particular, for the effective delivery of frontline material.
- Published
- 2019
- Full Text
- View/download PDF
48. Giant aneurysms of the distal posterior inferior cerebellar artery – systematic review.
- Author
-
Hall, Samuel, Steinfort, Brendan, and Dexter, Mark
- Subjects
- *
ANEURYSMS , *ENDOVASCULAR surgery , *ARTERIOVENOUS malformation , *ARTERIES , *PICA (Pathology) , *MUCOCUTANEOUS lymph node syndrome - Abstract
Posterior inferior cerebellar artery (PICA) aneurysms are uncommon and are typically found at the origin or proximal segments of the vessel. Giant aneurysms are uncommon and present unique treatment challenges. Giant distal PICA aneurysms are exceedingly rare and have traditionally been managed via open surgical approaches. A total of 207 studies were assessed, identifying 26 cases of giant distal PICA aneurysms from 26 separate publications. One additional case is described followed by a review of presentation, anatomical characteristics, treatment and outcome. Presentation was due to local mass effect in 19 (70%), hydrocephalus in 4 (15%) and acute haemorrhage in 5 (19%). All reported cases were partially (86%) or completely (14%) thrombosed. The telovelotonsillar segment was involved in 18/24 (75%) cases. Two cases (7%) were associated with an arteriovenous malformation. Twenty-two (81%) were managed surgically and 5 (19%) managed endovascularly. Outcome was good in 22 (85%) and poor in one (4%). Giant distal PICA aneurysms can be managed effectively through a variety of open surgical and endovascular techniques. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
49. Impact of improved representation of VOC emissions and production of NOx reservoirs on modeled urban ozone production.
- Author
-
Travis, Katherine R., Nault, Benjamin A., Crawford, James H., Bates, Kelvin H., Blake, Donald R., Cohen, Ronald C., Fried, Alan, Hall, Samuel R., Huey, L. Greg, Lee, Young Ro, Meinardi, Simone, Min, Kyung-Eun, Simpson, Isobel J., and Ullman, Kirk
- Subjects
ACETALDEHYDE ,POLYACRYLONITRILES ,ENVIRONMENTAL research ,OZONE ,LIQUEFIED petroleum gas ,PEROXYACETYL nitrate ,VOLATILE organic compounds - Abstract
The fraction of urban volatile organic compounds (VOC) emissions attributable to fossil fuel combustion has been declining in many parts of the world, resulting in a need to better constrain other anthropogenic sources of these emissions. During the National Institute of Environmental Research (NIER) and National Aeronautics and Space Administration (NASA) Korea-United States Air Quality (KORUS-AQ) field study in Seoul, South Korea during May–June 2016, air quality models underestimated ozone, formaldehyde, and peroxyacetyl nitrate (PAN) indicating an underestimate of VOCs in the emissions inventory. Here, we use aircraft observations interpreted with the GEOS-Chem chemical transport model to assess the need for increases in VOC emissions. We find that the largest increases are attributable to compounds associated with volatile chemical products, liquefied petroleum gas (LPG) and natural gas emissions, and long-range transport. Revising model chemistry to better match observed VOC speciation together with increasing model emissions of underestimated VOC species increased calculated OH reactivity by +2 s
-1 and ozone production by 2 ppb hr-1 . Ozone increased by 6 ppb below 2 km and 9 ppb at the surface, and formaldehyde and acetaldehyde increased by 30 % and 120 % aloft, respectively, all in better agreement with observations. The larger increase in acetaldehyde was attributed to ethanol emissions which we found to be as important for ozone production as isoprene or alkenes. The increased acetaldehyde largely resolved the model PAN bias. The need for additional unmeasured VOCs however was indicated by a remaining model bias of -1 ppb in formaldehyde and 57 % and 52 % underestimate in higher peroxynitrates (PNs) and alkyl nitrates (ANs), respectively. We added additional chemistry to the model to represent an additional six PNs from observed VOCs but were unable to account for the majority of missing PNs. However, four of these PNs were modeled at concentrations similar to other commonly measured PNs (>2 % of PAN) indicating that these should be measured in future campaigns. We hypothesize that emissions of oxygenated VOCs (OVOCs) such as >C5 aldehydes from cooking and/or alkenes associated with volatile chemical products could produce both PNs and ANs and improve remaining model biases. Emerging research on the emissions and chemistry of these species will soon allow for modeling of their impact on local and regional photochemistry. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
50. Using observed urban NOx sinks to constrain VOC reactivity and the ozone and radical budget in the Seoul Metropolitan Area.
- Author
-
Nault, Benjamin A., Travis, Katherine R., Crawford, James H., Blake, Donald R., Campuzano-Jost, Pedro, Cohen, Ronald C., DiGangi, Joshua P., Diskin, Glenn S., Hall, Samuel R., Huey, L. Gregory, Jimenez, Jose L., Kim, Kyung-Eun, Lee, Young R., Simpson, Isobel J., Ullmann, Kirk, and Wisthaler, Armin
- Subjects
METROPOLITAN areas ,RADICALS (Chemistry) ,OZONE ,VOLATILE organic compounds ,AIR quality - Abstract
Ozone (O
3 ) is an important secondary pollutant that impacts air quality and human health. Eastern Asia has high regional O3 background due to the numerous sources and increasing and rapid industrial growth, which impacts the Seoul Metropolitan Area (SMA). However, SMA has also been experiencing increasing O3 driven by decreasing NOx emissions, highlighting the role of local, in-situ O3 production on SMA. Here, comprehensive gas-phase measurements collected on the NASA DC-8 during the NIER/NASA Korea United States-Air Quality (KORUS-AQ) study are used to constrain the instantaneous O3 production rate over the SMA. The observed NOx oxidized products support the importance of non-measured peroxy nitrates (PNs) in the O3 chemistry in SMA, as they accounted for ~49 % of the total PNs. Using the total measured PNs (ΣPNs) and alkyl and multifunctional nitrates (ΣANs), unmeasured volatile organic compound (VOC) reactivity (R(VOC)) is constrained and found to range from 1.4 – 2.1 s-1 . Combining the observationally constrained R(VOC) with the other measurements on the DC-8, the instantaneous net O3 production rate, which is as high as ~10 ppbv hr-1 , along with the important sinks of O3 and radical chemistry, are constrained. This analysis shows that ΣPNs play an important role in both the sinks of O3 and radical chemistry. Since ΣPNs are assumed to be in steady-state, the results here highlight the role ΣPNs play in urban environments in reducing net O3 production, but ΣPNs can potentially lead to increased net O3 production downwind due to their short lifetime (~1 hr). The results provide guidance for future measurements to identify the missing R(VOCs) and ΣPNs production. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
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