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RAMSES II - The Retrieval Algorithm for Microwave Sounders in Earth Science (II)
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SN 2019hcc: a Type II supernova displaying early O ii lines
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Effect of Zn(II) coprecipitation on Mn(II)-induced reductive transformation of birnessite
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Element Redistribution in Irradiation Metallic Fuel from the Experimental Breeder Reactor-II (EBR-II)
This poster was prepared for the Intern Poster Session 2024, and it contains an analysis of constituent redistribution and diffusion of fuel and cladding constituents in the fuel-cladding chemical interaction region using results from electron microprobe analysis.
Enhanced Biochar for Soil Reclamation Co-Produced by a Drop-In Biofuels Process, US DOE SBIR Phase II Final Report, DOE_DE-SC0022445_II_Final_OSTI
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The ultraviolet IUE spectrum of the population II horizontal-branch A star HD 109995
Eight SWP and six LWP high dispersion IUE images of the field horizontal-branch A star HD 109995 have been averaged to increase the signal-to-noise ratio. The line density in the UV is greater than that of the optical region, but less than that of comparable population I A stars. Many of the identified lines are those of Fe II. Lines of C I, C II, N I, O I, Mg I, Mg II, Al II, Al III, Si I, Si II, P II, S I, Cl I, Ti II, V II, Cr II, Mn II, Fe I, Co II, Ni II, Zn II, and Ge II are also present. Definite interstellar lines of C II, Mg I, Mg II, Al II, Si II, and Fe II were found.
Far Outer Galaxy H II Regions
We have made a multifrequency (6, 3.6, and 2 cm), high-resolution (3"-6"), radio continuum survey of IRAS selected sources from the catalogue of Wouterloot & Brand (1989) to search for and study H II regions in the far outer Galaxy. We identified 31 sources in this catalog with well determined galactocentric distances, and with R approx.. greater than 15 kpc and L(sub FIR) approx.greater than 10(exp 4) solar luminosity, indicating the presence of high-mass star-formation. We have observed 11 of these sources with the Very Large Array (VLA). We observed the sources at 6 and 2 cm using "scaled arrays", making possible a direct and reliable comparison of the data at these two wavelengths for the determination of spectral indices. We detected a total of 12 radio sources, of which 10 have spectral indices consistent with optically-thin free-free emission from H II regions. Combined with previous VLA observations by other investigators, we have data on a total of 15 H II regions at galactocentric distances of 15 to 18.2kpc, among the most remote H II regions found in our Galaxy. The sizes of the H II regions range from approx. less than 0.10 to 2.3 pc. Using the measured fluxes and sizes, we determine the electron densities, emission measures, and excitation parameters of the H II regions, as well as the fluxes of Lyman continuum photons needed to keep the nebulae ionized. The sizes and electron densities are consistent with most of the sources detected in this survey being compact or ultracompact H II regions. Seven of the fifteen H II regions have sizes approx. less than 0.20 pc. Assuming simple pressure-driven expansion of the H II regions, these sizes indicate ages approx. less than 5 x 10(exp 4) yr, or only 1% of the lifetime of an O star, which implies an unlikely overabundance of O stars in the outer Galaxy. Thus, the large number of compact H II regions suggests that the time these regions spend in a compact phase must be much longer than their dynamical expansion times. Five of the fifteen H II regions have cometary shapes; the remainder are spherical or unresolved. Comparison of the radio continuum data with molecular line maps suggests that the cometary shape of the two H II regions in S 127 may be due to pressure confinement of the expanding ionized gas, as in the "blister" or "champagne flow" models of H II regions. Comparison of the radio continuum data with the IRAS far-infrared data indicates that the five most luminous H II regions are consistent with a single 0 or B star exciting a dust-free H II region. Subject headings: stars: formation - ISM: H II regions - ISM: individual objects: S 127 radio continuum: interstellar
Ultraviolet illuminated molecular cloud boundaries: Extended (C II) 158 micrometer emission toward L1630
The construction of a large scale map of the 158 micrometer C+ line toward the L1630/Orion B molecular cloud, covering an approximately 35' by 45' area which includes the NGC 2024 H II region, zeta-Ori, the reflection nebula NGC 2023, and the Horsehead nebula, is reported. Emission in the C II line is very widespread. The line was detected at levels in excess of a few 0.0001 erg/sq cm/s/sr over almost the entire mapped region. Extended emission associated with the NGC 2024 H II region and its envelope accounts for more than half of the C II flux. Over this approximately 1.5 by 2.5 pc region, the amount of gas phase carbon in the form of C+ is comparable to the amount of carbon in CO. This result, together with the C II distribution implies that C II emission arises on the surface of clumps throughout the cloud rather than in a single layer at the H II region boundary. Away from the H II region, most of the C II emission comes from the western edge of the L1630 cloud and probably results from excitation by external OB stars. The overall extent of the C II emission is comparable to that of millimeter molecular lines but the distributions are different in detail. The difference in C II and molecular line distributions, in particular, the larger extent of the C II emission west of NGC 2024 implies large variations in the ratio of the C II and J = 1 towards 0 intensities. Models of photon dominated regions can explain the relation between C II and CO intensities only if the cloud edges and cloud interior are considered separately. A method for using C II and radio continuum emission to characterize the relationship between OB stars and photon dominated regions is proposed.
Ultraviolet-illuminated molecular cloud boundaries: Extended (C II) 158 micron emission toward L1630
We have made a large-scale map of the 158 micrometers C(+) line toward the L1630/Orion B molecular cloud. The map covers a approximately 35 min x 45 min area which includes the NGC 2024 H II region, zeta Ori, the reflection nebula NGC 2023, and the Horsehead nebula. Emission in the (C II) line is very widespread. The line was detected at levels in excess of a few 10(exp -4) ergs/sq cm/s/sr over almost the entire mapped region. Extended emission associated with the NGC 2024 H II region and its envelope accounts for more than half of the (C II) flux. Over this approximately 1.5 x 2.5 pc region, the amount of gas-phase carbon in the form of C(+) is comparable to the amount of carbon in CO. This result, together with the (C II) distribution, implies that (C II) emission arises on the surfaces of clumps throughout the cloud rather than in a single layer at the H II region boundary. Away from the H II region, most of the (C II) emission comes from the western edge of the L1630 cloud and probably results from excitation by external OB stars. The overall extent of the (C II) emission is comparable to that of millimeter molecular lines, but the distributions are different in detail. The difference in (C II) and molecular line distributions, in particular, the larger extent of the (C II) emission west of NGC 2024 implies large variations in the radio of the (C II) and CO J = 1 goes to 0 intensities. Models of photon-dominated regions can explain the relation between (C II) and CO intensities only if one considers the cloud edges and cloud interior separately. We propose a method for using (C II) and radio continuum emission to characterize the relationship between OB stars and photon-dominated regions.
Type II Radio Bursts and Their Association With Coronal Mass Ejections in Solar Cycles 23 and 24
Context. Meter-wavelength type II solar radio bursts are thought to be the signatures of shock-accelerated electrons in the corona. Studying these bursts can give information about the initial kinematics, dynamics, and energetics of coronal mass ejections (CMEs) in the absence of white-light observations. Aims. We investigate the occurrence of type II bursts in solar cycles 23 and 24 and their association with CMEs. We also explore whether type II bursts might occur in the absence of a CME. Methods. We performed a statistical analysis of type II bursts that occurred between 200 and 25 MHz in solar cycles 23 and 24 and determined the temporal association of these radio bursts with CMEs. We categorized the CMEs based on their linear speed and angular width and studied the distribution of type II bursts with fast (≥500 km s−1 ), slow (<500 km s−1), wide (≥60◦), and narrow (<60◦) CMEs. We explored the dependence of type II bursts occurrence on the phases of the solar cycle. Results. Our analysis shows that during solar cycles 23 and 24, 768 and 435 type II bursts occurred, respectively. Of these, 79% were associated with CMEs in solar cycle 23, and 95% were associated with CMEs in solar cycle 24. However, only 4% and 3% of the total number of CMEs were accompanied by type II bursts in solar cycle 23 and 24, respectively. Most of the type II bursts in both cycles were related to fast and wide CMEs (48%). We also determined the typical drift rate and duration for type II bursts, which is 0.06 MHz s−1 and 9 min. Our results suggest that type II bursts dominate at heights ≈1.7−2.3±0.3 R . A clear majority have an onset height around 1.7 ± 0.3 R assuming the four-fold Newkirk model. Conclusions. The results indicate that most of the type II bursts had a white-light CME counterpart, but a few type II bursts lacked a clear CME association. There were more CMEs in cycle 24 than in cycle 23. However, cycle 24 contained fewer type II radio bursts than cycle 23. The onset heights of type II bursts and their association with wide CMEs reported in this study indicate that the early lateral expansion of CMEs may play a key role in the generation of these radio bursts.
Comparison of SBUV and SAGE II ozone profiles: Implications for ozone trends
Solar backscattered ultraviolet (SBUV) ozone profiles have been compared with Stratospheric Aerosol and Gas Experiment (SAGE) II profiles over the period October 1984 through June 1990, when data are available from both instruments. SBUV measurements were selected to closely match the SAGE II latitude/longitude measurement pattern. There are significant differences between the SAGE II sunrise and the sunset zonal mean ozone profiles in the equatorial zone, particularly in the upper stratosphere, that may be connected with extreme SAGE II solar azimuth angles for tropical sunrise measurements. Calculation of the average sunset bias between SBUV and SAGE II ozone profiles shows that allowing for diurnal variation in Umkehr layer 10, SBUV and SAGE II agree to within +/- 5% for the entire stratosphere in the northern midlatitude zone. The worst agreement is seen at southern midlatitudes near the ozone peak (disagreements of +/- 10%), apparently the result of the SBUV ozone profile peaking at a lower altitude than SAGE. The integrated ozone columns (cumulative above 15 km) agree very well, to within +/- 2.3% in all zones for both sunset and sunrise measurements. A comparison of the time dependence of SBUV and SAGE II shows that there was less than +/- 5% relative drift over the 5.5 years for all altitudes except below 25 km, where the SBUV vertical resolution is poor. The best agreement with SAGE is seen in the integrated column ozone (cumulative above 15 km), where SAGE II has a 1% negative trend relative to SBUV over the comparison period. There is a persistent disagreement of the two instruments in Umkehr layers 9 and 10 of +/- 4% over the 5.5-year comparison period. In the equatorial zone this disagreement may be caused in part by a large positive trend (0.8 K per year) in the National Meteorologica Center temperatures used to convert the SAGE II measurement of ozone density versus altitude to a pressure scale for comparison with SBUV. In the middle stratosphere (30-40 km), SBUV shows a 2-4% negative drift relative to SAGE II. If the actual ozone trends are considered, SBUV and SAGE II agree in showing little ozone change (less than 2%) between 1984 and 1990, except in layer 3 where SAGE II measures a large ozone decrease. But over 11 years, SBUV measured a 7% per decade ozone decrease between 40 and 50 km, decreasing in magnitude at lower altitudes, in good agreement with 11-year trends derived from the average of 5 Umkehr stations.
Documentation of angiotensin II receptors in glomerular epithelial cells
Angiotensin II decreases glomerular filtration rate, renal plasma flow, and glomerular capillary hydraulic conductivity. Although angiotensin II receptors have been demonstrated in mesangial cells and proximal tubule cells, the presence of angiotensin II receptors in glomerular epithelial cells has not previously been shown. Previously, we have reported that angiotensin II caused an accumulation of cAMP and a reorganization of the actin cytoskeleton in cultured glomerular epithelial cells. Current studies were conducted to verify the presence of angiotensin II receptors by immunological and non-peptide receptor ligand binding techniques and to ascertain the activation of intracellular signal transduction in glomerular epithelial cells in response to angiotensin II. Confluent monolayer cultures of glomerular epithelial cells were incubated with angiotensin II, with or without losartan and/or PD-123,319 in the medium. Membrane vesicle preparations were obtained by homogenization of washed cells followed by centrifugation. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of membrane proteins followed by multiscreen immunoblotting was used to determine the presence of angiotensin II receptor type 1 (AT1) or type 2 (AT2). Angiotensin II-mediated signal transduction in glomerular epithelial cells was studied by measuring the levels of cAMP, using radioimmunoassay. Results obtained in these experiments showed the presence of both AT1 and AT2 receptor types in glomerular epithelial cells. Angiotensin II was found to cause an accumulation of cAMP in glomerular epithelial cells, which could be prevented only by simultaneous use of losartan and PD-123,319, antagonists for AT1 and AT2, respectively. The presence of both AT1 and AT2 receptors and an increase in cAMP indicate that glomerular epithelial cells respond to angiotensin II in a manner distinct from that of mesangial cells or proximal tubular epithelial cells. Our results suggest that glomerular epithelial cells participate in angiotensin II-mediated control of the glomerular filtration barrier.
Risk Characterization Research for Artemis II: Human Factors and Behavioral Performance
BACKGROUND Artemis II will be the first time NASA astronauts go beyond low-Earth orbit (LEO) since the Apollo era, and the first astronauts heading into space in the Orion vehicle. As such, it provides a critical opportunity to refine our understanding of the likelihood and consequences associated with the Behavioral Medicine (BMed), Team, Human System Integration Architecture (HSIA), and Sleep Risks, and prepare for future Moon and Mars missions. However, Artemis II research efforts are uniquely shaped by in-mission data collection constraints. There is currently no in-mission crew time available to complete measures. In-mission data will need to be collected unobtrusively from available data streams (e.g., audiovisual, existing records such as schedules, and actigraphy). Accordingly, the overarching goal of our research is to utilize Artemis II data to further define the likelihood and consequences of these risks, and to create an unobtrusive research infrastructure that can be expanded to include future Artemis missions. This goal spans four aims across three research phases: (1) identify and operationally define key performances metrics and constructs across the four aforementioned risks, (2) develop an unobtrusive methodology and coding scheme for in-mission data collection, (3) characterize performance decrements due to Bmed, Team, HSIA, and Sleep Risks, and (4) develop a data infrastructure for future Artemis missions. The following details results of Phase I efforts in which we address Aims 1 and 2 to develop an unobtrusive measurement plan and coding scheme to capture key constructs, contributing factors, and performance decrements across each risk area. METHOD As part of Phase I, we conducted an interdisciplinary literature review and consulted with SMEs to identify unobtrusive methodologies that leverage text, audio, and/or video data as well as conceptualize key performance metrics, contributing factors, and BMed, Team, HSIA, and Sleep risk constructs related to performance decrements. The Phase I effort resulted in a finalized pre- and post-mission protocol for Artemis II, along with a measurement and coding scheme for in-mission Artemis II data. Phase II will involve data collection from the upcoming Artemis II mission. Phase III will include data processing, coding, depiction, analysis, and report writing of the Artemis II data. RESULTS & DISCUSSION To date, we have completed Phase I efforts. Specifically, we identified BMed, Team, HSIA, and Sleep risk constructs related to performance metrics, summarized how these constructs can be measured using audiovisual data collected during the mission, and worked with NASA’s HFBP Element to finalize a data collection protocol that leverages audiovisual input from the Orion spacecraft system. Our protocol includes novel unobtrusive methodologies that adhere to in-mission data streams and subsequent constraints (e.g., limited storage space on GoPro cameras, ambient noise impeding audio files) to best capture in-mission phenomena across each risk area. We will present our results from Phase I efforts, namely best practices for unobtrusive measurement as identified through literature reviews and SME consultation as well as codebook excerpts for use in Artemis II. We will include a description of planned work as we prepare for Phase II and Phase III of this research plan and the Artemis II mission itself. SUMMARY We describe progress on our Human Factors and Behavioral Performance Research for Artemis II study.
Mn(II)-induced phase transformation of Mn(IV) oxide in seawater
Manganese (Mn) oxides are key components of oceanic and lacustrine Mn nodules and influence metal cycling through oxidation and adsorption processes. Layered Mn oxides (LMOs) are the most common minerals in these nodules and the immediate products of microbially mediated Mn(II) oxidation by O 2 . LMOs can transform into tunneled Mn oxides (TMOs), Mn oxyhydroxides (MnOOH), or Mn(II,III) phase (Mn 3 O 4 ). LMOs often concur with Mn(II) in the environment and the adsorption and oxidation of Mn(II) by LMOs can greatly promote the transformation of LMOs to those phases. However, the Mn(II)-promoted transformation of LMOs in seawater—rich in various cations (300 mM Na + , 10 mM K + , 50 mM Ca 2+ , and 10 mM Mg 2+ ) remains poorly understood. We examined the transformation of δ-MnO 2 in artificial seawater (pH 8.2) under anoxic conditions with the Mn(II)/MnO 2 ratio (r) ranging from 0.08 to 3.83. To assess the effect of ionic strength (IS), parallel experiments were conducted in a mixed 530 mM NaCl and 10 mM KCl solution (having seawater ionic strength but without Ca 2+ and Mg 2+ ) and in 100 mM NaCl solution as a control. At low r (0.08), δ-MnO 2 transformed into triclinic birnessite and a 4 × 4 TMO in 100 mM NaCl solution, which, however, was suppressed in seawater due to strong interactions of Ca 2+ /Mg 2+ with δ-MnO 2 . In the mixed 530 mM NaCl and 10 mM KCl solution (the same ionic strength as of seawater), the transformation occurred extensively but the products had lower crystallinity compared to in 100 mM NaCl solution. At the high Mn(II)/MnO 2 ratios (0.5 ≤ r ≤ 3.83), δ-MnO 2 transformed extensively into MnOOH phases and hausmannite (Mn 3 O 4 ) in 100 mM NaCl solution. The seawater suppressed the transformation, but the suppression became weaker with increasing Mn(II)/MnO 2 ratio. For example, the transformation was completely suppressed at r = 0.5 but essentially negligible at r = 3.83. The suppression at these high Mn(II)/MnO 2 ratios was mainly ascribed to the influence of Ca 2+ and Mg 2+ rather than of the high IS, and the weaker suppression at the higher Mn(II)/MnO 2 ratio suggests stronger competition of Mn(II) with Ca 2+ /Mg 2+ for interacting with δ-MnO 2 . Moreover, the composition and crystallinity of the transformation products (i.e., the relative abundance of MnOOH (α, β, and γ) and Mn 3 O 4 ) were influenced by both the high ionic strength and the presence of Ca 2+ and Mg 2+ . Therefore, even though Ca 2+ and Mg 2+ concentrations are much lower than Na + in seawater, their impacts on the transformation are dominant. Our study explains why MnOOH phases, hausmannite, and TMOs are less common than LMOs in oceanic environments, partially because seawater chemistry suppresses their formation. LMOs are the most reactive for metal adsorption and oxidation among all Mn oxides. Thus, the high stability of LMOs in an oceanic environment confers the high impacts of Mn oxides on metal cycling in the ocean.
Galactic interstellar abundance surveys with IUE. II - The equivalent widths and column densities
This paper continues a survey of interstellar densities, abundances, and cloud structure in the Galaxy, using the International Ultraviolet Explorer (IUE) satellite. Equivalent widths of 18 ultraviolet resonance transitions are presented and column densities for Si II, Mn II, Fe II, S II, and Zn II toward 261 early-type stars are derived. These equivalent widths and column densities agree within the stated errors of earlier Copernicus, BUSS, or IUE surveys of Mn II, Fe II, S II, and Zn II for 45 stars in common. The column densities are derived from single-component curves of growth with a common b-value based on that of Fe II and Si II.
Evaluation of SAGE II and Balloon-Borne Stratospheric Aerosol Measurements
Under funding from this proposal we evaluated measurements of stratospheric sulfate aerosols from three platforms. Two were satellite platforms providing solar extinction measurements, the Stratospheric Aerosol and Gas Experiment (SAGE) II using wavelengths from 0.386 - 1.02 microns, and the Halogen Occultation Experiment (HALOE) using wavelengths from 2.45 to 5.26 microns. The third set of measurements was from in situ sampling by balloonborne optical particle counters (OPCs). The goal was to determine the consistency among these data sets. This was accomplished through analysis of the existing measurement records, and through additional balloonborne OPC flights coinciding with new SAGE II observations over Laramie, Wyoming. All analyses used the SAGE II v 6.0 data. This project supported two balloon flights per year over Laramie dedicated to SAGE II coincidence. Because logistical factors, such as poor surface weather or unfavorable payload impact location, can make it difficult to routinely obtain close coincidences with SAGE II, we attempt to conduct nearly every Laramie flight (roughly one per month) in conjunction with a SAGE II overpass. The Laramie flight frequency has varied over the years depending on field commitments and funding sources. Current support for the Laramie measurements is from the National Science Foundation in addition to support from this NASA grant. We have also completed a variety of comparisons using aerosol measurements from SAGE II, OPCs, and HALOE. The instruments were compared for their various estimates of aerosol extinction at the SAGE II wavelengths and for aerosol surface area. Additional results, such as illustrated here, can be found in a recently accepted manuscript describing comparisons between SAGE II, HALOE, and OPCs for the period 1982 - 2000. While overall, the impression from these results is encouraging, the agreement of the measurements changes with latitude, altitude, time, and parameter. In the broadest sense, these comparisons fall into two categories: high aerosol loading (volcanic periods) and low aerosol loading (background periods and altitudes above 25 km). When the aerosol amount is low SAGE II and HALOE extinctions are higher than the OPC estimates, while the SAGE II surface areas are lower than HALOE and the OPCS. Under high loading conditions, all three instruments mutually agree to within 50%.